Evacuation in the Social Force Model is not stationary

An evacuation process is simulated within the Social Force Model. Thousand pedestrians are leaving a room by one exit. We investigate the stationarity of the distribution of time lags between instants when two successive pedestrians cross the exit. The exponential tail of the distribution is shown to gradually vanish. Taking fluctuations apart, the time lags decrease in time till there are only about 50 pedestrians in the room, then they start to increase. This suggests that at the last stage the flow is laminar. In the first stage, clogging events slow the evacuation down. As they are more likely for larger crowds, the flow is not stationary. The data are investigated with detrended fluctuation analysis.Comment: 7 pages, 3 figures; PACS numbers: 89.75.Fb, 05.40.-a, 05.45.Tp, 89.40.B

Empathy, compassion, and theory of mind in obsessive‐compulsive disorder

Objectives: Individuals with obsessive-compulsive disorder (OCD) often suffer from impairments in social functioning. This study investigates differences in empathy, compassion, and Theory of Mind (ToM) in individuals with OCD as a possible cause for social functioning deficits. Design: Sixty-four individuals diagnosed with OCD and 62 healthy individuals completed a naturalistic behavioural task (EmpaToM) and a self-report measure (Interpersonal Reactivity Index, IRI). Methods: Three preregistered repeated measures analyses of variance (ANOVAs). Results: People with OCD exhibited higher empathy levels - namely increased sharing of others' suffering - in the EmpaToM task and reported more distress (IRI) compared with healthy individuals. Furthermore, no differences in compassion (EmpaToM) between both groups emerged, although people with OCD reported more concern for others (IRI) compared with healthy individuals. Concerning the ToM, no group differences were detected, neither in the behavioural task, nor self-report. Conclusion: By investigating OCD with diverse scientific practices we shed light on the higher levels of empathy exhibited by individuals with OCD, which are relevant for clinical practice and our understanding of OCD symptomatology. Practitioner points: People with obsessive-compulsive disorder show higher levels of empathy, that is the increased sharing of others' suffering, compared with healthy individuals in both a traditional self-report and a naturalistic task. Regarding compassion, that is caring for others, their self-reported compassion was higher in people with OCD. In Theory of Mind, that is cognitively understanding the situation of another person, no differences have been found neither at self-report nor in a naturalistic task compared with healthy individuals. Independent of traditional interventions, it could prove useful to improve emotion regulation skills so people with OCD learn to cope with empathic distress. Furthermore, it might strengthen the treatment gains and lower dropout rates if the social mind and consequently social relationships become a topic in the treatment and prevention of OCD

Towards an evolutionary model of city sustainability

In part stimulated by the computer game industry, reasonable progress has been made in the dynamic modelling of urban growth and land use change. However, sustainability considerations in this work remain to be addressed. Yet the environmental impact of cities, already accommodating around half the global population, is both profound and increasing. It is thus important that our cities evolve in the most sustainable way possible. To guide this process it is useful to pose and test alternative urban planning scenarios. To this end, we propose the development of a new advanced computer modelling paradigm and discuss progress that is under way to realise it. In this we discuss developments in modelling the urban microclimate, the operation of buildings and services and the behaviour of humans. We also discuss ways of evaluating energy and matter flows and the potential to handle transportation and social and economic preferences in decision making. Finally, we consider this capability within a framework that will support self-organising city evolution to evaluate the future fitness of alternativ

A new purple sulfur bacterium from saline littoral sediments, Thiorhodotvibrio winogradskyi gen. nov. and sp. nov.

Two strains of a new purple sulfur bacterium were isolated in pure culture from the littoral sediment of a saline lake (Mahoney Lake, Canada) and a marine microbial mat from the North Sea island of Mellum, respectively. Single cells were vibrioid-to spirilloid-shaped and motile by means of single polar flagella. Intracellular photosynthetic membranes were of the vesicular type. As photosynthetic pigments, bacteriochlorophyll a and the carotenoids lycopene, rhodopin, anhydrorhodovibrin, rhodovibrin and spirilloxanthin were present. Hydrogen sulfide and elemental sulfur were used under anoxic conditions for phototrophic growth. In addition one strain (06511) used thiosulfate. Carbon dioxide, acetate and pyruvate were utilized by both strains as carbon sources. Depending on the strain propionate, succinate, fumarate, malate, tartrate, malonate, glycerol or peptone may additionally serve as carbon sources in the light. Optimum growth rates were obtained at pH 7.2, 33 °C, 50 mol m-2 s-1 intensity of daylight fluorescent tubes and a salinity of 2.2–3.2% NaCl. During growth on sulfide, up to ten small sulfur globules were formed inside the cells. The strains grew microaerophilic in the dark and exhibited high specific respiration rates. No vitamins were required for growth. The DNA base composition was 61.0–62.4 mol% G+C. The newly isolated bacterium belongs to the family chromatiaceae and is described as a member of a new genus and species, Thiorhodovibrio winogradskyi gen. nov. and sp. nov. with the type strain SSP1, DSM No. 6702

Dissolved Organic Matter in the Upwelling System off Peru: Imprints of Bacterial Activity and Water Mass Characteristics

Microbial degradation of dissolved organic matter (DOM) contributes to the formation and preservation of oxygen minimum zones (OMZs) in the ocean, but information on the spatial distribution and molecular composition of DOM in OMZ regions is scarce. We quantified molecular components of DOM that is, dissolved amino acids (DAA) and dissolved combined carbohydrates (DCCHO), in the upwelling region off Peru. We found the highest concentrations of DCCHO in fully oxygenated surface waters steeply declining at shallow depth. The highest DAA concentrations were observed close to the surface also, but attenuation of DAA concentration over depth was less pronounced. Compositional changes of DCCHO were strongest within more oxygenated waters. Compositional changes of DAA were also evident under suboxic conditions (<5 µmol O2 kg−1) and indicated bacterial peptide degradation. Moreover, specific free amino acids (alanine and threonine) were enhanced within suboxic waters, pointing to a potential production of dissolved organic nitrogen under suboxic conditions. Our results therewith suggest that deoxygenation supports a spatial decoupling of DCCHO and DAA production and degradation dynamics and give new insights to carbon and nitrogen cycling in the OMZ off Peru

Upwelling on the continental slope of the Alaskan Beaufort Sea : storms, ice, and oceanographic response

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 114 (2009): C00A13, doi:10.1029/2008JC005009.The characteristics of Pacific-born storms that cause upwelling along the Beaufort Sea continental slope, the oceanographic response, and the modulation of the response due to sea ice are investigated. In fall 2002 a mooring array located near 152°W measured 11 significant upwelling events that brought warm and salty Atlantic water to shallow depths. When comparing the storms that caused these events to other Aleutian lows that did not induce upwelling, interesting trends emerged. Upwelling occurred most frequently when storms were located in a region near the eastern end of the Aleutian Island Arc and Alaskan Peninsula. Not only were these storms deep but they generally had northward-tending trajectories. While the steering flow aloft aided this northward progression, the occurrence of lee cyclogenesis due to the orography of Alaska seems to play a role as well in expanding the meridional influence of the storms. In late fall and early winter both the intensity and frequency of the upwelling diminished significantly at the array site. It is argued that the reduction in amplitude was due to the onset of heavy pack ice, while the decreased frequency was due to two different upper-level atmospheric blocking patterns inhibiting the far field influence of the storms.The following grants provided support for this study: National Science Foundation grants OPP-0731928 (R.S.P.) and OPP-0713250 (R.S.P. and P.S.F.), Office of Naval Research grant N00014-07-1-1040 (D.J.T. and R.A.G.), Natural Sciences and Engineering Research Council of Canada (G.W.K.M.), Woods Hole Oceanographic Institution Arctic Initiative (J.Y.)