When Does a Newcomer Contribute to a Better Performance? A Multi-Agent Study on Self-Organising Processes of Task Allocation

This paper describes how a work group and a newcomer mutually adapt. We study two types of simulated groups that need an extra worker, one group because a former employee had left the group and one group because of its workload. For both groups, we test three conditions, newcomers being specialists, newcomers being generalists, and a control condition with no newcomer. We hypothesise that the group that needs an extra worker because of its workload will perform the best with a newcomer being a generalist. The group that needs an extra worker because a former employee had left the group, will perform better with a specialist newcomer. We study the development of task allocation and performance, with expertise and motivation as process variables. We use two performance indicators, the performance time of the slowest agent that indicates the speed of the group and the sum of performance of all agents to indicate labour costs. Both are indicative for the potential benefit of the newcomer. Strictly spoken the results support our hypotheses although the differences between the groups with generalists and specialists are negligible. What really mattered was the possibility for a newcomer to fit in.Task Allocation, Group Processes, Psychological Theory, Small Groups, Self-Organisation

Simulating the Emergence of Task Rotation

In work groups, task rotation may decrease the negative consequences of boredom and lead to a better task performance. In this paper we use multi agent simulation to study several organisation types in which task rotation may or may not emerge. By looking at the development of expertise and motivation of the different agents and their performance as a function of self-organisation, boredom, and task rotation frequency, we describe the dynamics of task rotation. The results show that systems in which task rotation emerges perform better than systems in which the agents merely specialise in one skill. Furthermore, we found that under certain circumstances, a task that leads to a high degree of boredom was performed better than a task causing a low level of boredom.Organisation, Task Rotation, Work Groups, Psychological Theory, Multi Agent Simulation

Multiple Sox genes are expressed in stem cells or in differentiating neuro-sensory cells in the hydrozoan Clytia hemisphaerica

<p>Abstract</p> <p>Background</p> <p>The <it>Sox </it>genes are important regulators of animal development belonging to the HMG domain-containing class of transcription factors. Studies in bilaterian models have notably highlighted their pivotal role in controlling progression along cell lineages, various <it>Sox </it>family members being involved at one side or the other of the critical balance between self-renewing stem cells/proliferating progenitors, and cells undergoing differentiation.</p> <p>Results</p> <p>We have investigated the expression of 10 <it>Sox </it>genes in the cnidarian <it>Clytia hemisphaerica</it>. Our phylogenetic analyses allocated most of these <it>Clytia </it>genes to previously-identified Sox groups: SoxB (<it>CheSox2, CheSox3, CheSox10, CheSox13, CheSox14</it>), SoxC (<it>CheSox12</it>), SoxE (<it>CheSox1, CheSox5</it>) and SoxF (<it>CheSox11</it>), one gene (<it>CheSox15</it>) remaining unclassified. In the planula larva and in the medusa, the <it>SoxF </it>orthologue was expressed throughout the endoderm. The other genes were expressed either in stem cells/undifferentiated progenitors, or in differentiating (-ed) cells with a neuro-sensory identity (nematocytes or neurons). In addition, most of them were expressed in the female germline, with their maternal transcripts either localised to the animal region of the egg, or homogeneously distributed.</p> <p>Conclusions</p> <p>Comparison with other cnidarians, ctenophores and bilaterians suggest ancient evolutionary conservation of some aspects of gene expression/function at the <it>Sox </it>family level: (i) many <it>Sox </it>genes are expressed in stem cells and/or undifferentiated progenitors; (ii) other genes, or the same under different contexts, are associated with neuro-sensory cell differentiation; (iii) <it>Sox </it>genes are commonly expressed in the germline; (iv) <it>SoxF </it>group genes are associated with endodermal derivatives. Strikingly, total lack of correlation between a given <it>Sox </it>orthology group and expression/function in stem cells/progenitors <it>vs</it>. in differentiating cells implies that <it>Sox </it>genes can easily switch from one side to the other of the balance between these fundamental cellular states in the course of evolution.</p

Dynamic thermo-mechanical properties of various flowable resin composites

This study compared the storage modulus (E’), the loss modulus (E’’) and the loss tangent (tan δ) of various flowable resin composites. Grandio Flow (GRF), GrandioSo Heavy Flow (GHF), Filtek Supreme XTE (XTE) and Filtek Bulk Fill (BUL) flowable resins and Clinpro Sealant (CLI) ultra-flowable pit and fissure sealant resin were used. 25 samples were tested using a dynamical mechanical thermal analysis system in bending mode. Measurements were taken within a temperature range of 10 to 55°C. The results were statistically analyzed using mixed-effect and repeated-measure analysis of variance followed by paired multiple comparisons. For all the materials, the E’ values decrease with temperature, whereas the tan δ values increase. Irrespective of the temperature, GHF and GRF present E’ and E’’ values significantly higher than all the other materials and CLI presents values significantly lower than all the other materials. Observation of the values for all the materials reveals a linear progression of the tan δ values with temperature. A variation in temperature within a physiological range generates modifications in mechanical properties without damaging the material, however. Filler content in volume terms appears to be the crucial parameter in the mechanical behavior of tested materials

When Does a Newcomer Contribute to a Better Performance? a Multi-Agent Study on Self- Organising Processes of Task Allocation

Abstract This paper describes how a work group and a newcomer mutually adapt. We study two types of simulated groups that need an extra worker, one group because a former employee had left the group and one group because of its workload. For both groups, we test three conditions, newcomers being specialists, newcomers being generalists, and a control condition with no newcomer. We hypothesise that the group that needs an extra worker because of its workload will perform the best with a newcomer being a generalist. The group that needs an extra worker because a former employee had left the group, will perform better with a specialist newcomer. We study the development of task allocation and performance, with expertise and motivation as process variables. We use two performance indicators, the performance time of the slowest agent that indicates the speed of the group and the sum of performance of all agents to indicate labour costs. Both are indicative for the potential benefit of the newcomer. Strictly spoken the results support our hypotheses although the differences between the groups with generalists and specialists are negligible. What really mattered was the possibility for a newcomer to fit in

IPC02-27158 THE INFLUENCE OF LAND USE AND DEPTH OF COVER ON THE FAILURE RATE OF GAS TRANSMISSION PIPELINES

ABSTRACT The first stage in performing a risk calculation is the failure rate assessment. In order to get reliable risk calculations, a good understanding of the failure rate of an underground pipeline is indispensable. Earlier studies already showed that extra cover significantly reduces the likelihood of damage caused by third party interference. This paper describes the influence of depth of cover based on the latest information on incidents. Moreover, the influence of population density on the damage rate of pipelines is studied

The QUEST initiative anemia study in ESRD: rationale and study protocol

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IPC02-27196 RECENT DEVELOPMENTS IN THE DESIGN AND APPLICATION OF THE PIPESAFE RISK ASSESSMENT PACKAGE FOR GAS TRANSMISSION PIPELINES

ABSTRACT PIPESAFE is a hazard and risk assessment package for gas transmission pipelines, developed by Advantica for an international group of gas pipeline companies. Although the likelihood of failure of transmission pipelines is very low, the possibility of failure and a subsequent fire cannot be discounted. PIPESAFE provides the means to take consistent and informed decisions on risk issues, including infringements to pipeline design codes, uprating of pipelines (i.e. to operate at higher pressures), pipeline routeing and land use planning. The development of PIPESAFE was first reported at IPC &apos;98. This paper describes recent enhancements to the package, validation of the predictions against full-scale experiments and incidents, and modifications to the risk calculation methods. The paper also describes risk criteria developed in the UK and The Netherlands, the background to their development, and the use of PIPESAFE to generate risk criteria included in the latest edition of the UK pipeline code IGE/TD/1

Ювілей Михайла Миколайовича Тарана

18 жовтня 2008 р. виповнилося 60 років відомому українському вченому-мінералогу, знаному в світі фахівцю в галузі фізики мінералів, доктору геолого-мінералогічних наук Михайлові Миколайовичу Тарану