Poissonian bursts in e-mail correspondence

Recent work has shown that the distribution of inter-event times for e-mail communication exhibits a heavy tail which is statistically consistent with a cascading Poisson process. In this work we extend the analysis to higher-order statistics, using the Fano and Allan factors to quantify the extent to which the empirical data depart from the known correlations of Poissonian statistics. The analysis shows that the higher-order statistics from the empirical data is indistinguishable from that of randomly reordered time series, thus demonstrating that e-mail correspondence is no more bursty or correlated than a Poisson process. Furthermore synthetic data sets generated by a cascading Poisson process replicate the burstiness and correlations observed in the empirical data. Finally, a simple rescaling analysis using the best-estimate rate of activity, confirms that the empirically observed correlations arise from a non-homogeneus Poisson process

Foraging under conditions of short-term exploitative competition: The case of stock traders

Theory purports that animal foraging choices evolve to maximize returns, such as net energy intake. Empirical research in both human and nonhuman animals reveals that individuals often attend to the foraging choices of their competitors while making their own foraging choices. Due to the complications of gathering field data or constructing experiments, however, broad facts relating theoretically optimal and empirically realized foraging choices are only now emerging. Here, we analyze foraging choices of a cohort of professional day traders who must choose between trading the same stock multiple times in a row---patch exploitation---or switching to a different stock---patch exploration---with potentially higher returns. We measure the difference between a trader's resource intake and the competitors' expected intake within a short period of time---a difference we call short-term comparative returns. We find that traders' choices can be explained by foraging heuristics that maximize their daily short-term comparative returns. However, we find no one-best relationship between different trading choices and net income intake. This suggests that traders' choices can be short-term win oriented and, paradoxically, maybe maladaptive for absolute market returns

Micro-bias and macro-performance

We use agent-based modeling to investigate the effect of conservatism and partisanship on the efficiency with which large populations solve the density classification task--a paradigmatic problem for information aggregation and consensus building. We find that conservative agents enhance the populations' ability to efficiently solve the density classification task despite large levels of noise in the system. In contrast, we find that the presence of even a small fraction of partisans holding the minority position will result in deadlock or a consensus on an incorrect answer. Our results provide a possible explanation for the emergence of conservatism and suggest that even low levels of partisanship can lead to significant social costs.Comment: 11 pages, 5 figure

Brain tumour growth in rats exposed to electromagnetic fields used in wireless cellular communication

In 1996 there was no convincing laboratory evidence that EMFs used in wireless communication could cause tumour promotion at non-thermal exposure levels. Therefore we then performed a study of the effects from exposure to such electromagnetic fields in the rat brain glioma model we were using in our research for brain tumour therapy. By stereotaxic technique rat glioma cells (RG2 or N32) were injected into the head of the right caudate nucleus in 154 pairs of Fischer 344 rats in both exposed and matched controls. Starting on day 5 after inoculation, the animals were exposed for 7 hours a day, 5 days a week during 2 - 3 weeks. Rats of both sexes were exposed to electromagnetic fields in the microwaves frequency range 915 MHz both as continuous waves (1 W), and as pulse-modulated at 4, 8, 16 and 217 Hz in 0.57 ms long pulses and 50 Hz in 6.67 ms pulses, all with a maximum power amplitude of 2 W per pulse. The animals were kept un-anaesthetized in well-ventilated TEM cells during 7 hours a day for 5 days a week for 2-3 weeks. Their matched controls were kept in identical TEM cells without EMF exposure. At the end of the exposure period the rat brains were examined histopathologically. The tumour size was measured with a calliper and the volume estimated as an ellipsoid. Our study of the 154 matched pairs of rats did not show any significant difference in tumour volume between animals exposed to 915 MHz microwaves, and those not exposed. Thus our results did not support that daily exposure to EMF promotes tumour growth when given from the fifth day after the start of tumour growth in the rat brain until the sacrifice of the animal 16 days later. In the present review our results published 1997 have been re-evaluated in terms of SAR dependence of tumour volume observed ratio (exposed / control). We thus surprisingly found that the shape of tumour volume-OR versus SAR response was of bath-tube pattern, similar to that found in our parallel studies of albumin leakage through the blood-brain barrier. Since the SAR varies between most other animal studies reviewed and human epidemiological studies this SAR dependence might explain the controversy in rendering the results

On Universality in Human Correspondence Activity

Identifying and modeling patterns of human activity has important ramifications in applications ranging from predicting disease spread to optimizing resource allocation. Because of its relevance and availability, written correspondence provides a powerful proxy for studying human activity. One school of thought is that human correspondence is driven by responses to received correspondence, a view that requires distinct response mechanism to explain e-mail and letter correspondence observations. Here, we demonstrate that, like e-mail correspondence, the letter correspondence patterns of 16 writers, performers, politicians, and scientists are well-described by the circadian cycle, task repetition and changing communication needs. We confirm the universality of these mechanisms by properly rescaling letter and e-mail correspondence statistics to reveal their underlying similarity.Comment: 17 pages, 3 figures, 1 tabl

S-100 protein levels in the blood of Fischer rats exposed to 915 MHz CW-microwaves and magnetic fields.

EnglishPersson, B. R. R., Nittby Redenbrant, H., Malmgren, L., Brun, A., and Salford, L. G. (2020). S-100 protein levels in the blood of Fischer rats exposed to 915 MHz CW-microwaves and magnetic fields. Acta Scientiarum Lundensia, Vol. 2020-005, pp. 1-9, ISSN 1651-5013Abstrakt.Syftet var att studera nivån av S-100 i blodprover som tagits från Fischer-344-råttor efter exponering för 915 MHz CW-mikrovågor och ELF-magnetfält i TEM-celler. Magnetfältsexponering ägde rum med TEM-cellen i ett Helmholtz-spolarrangemang med antingen 50 Hz sinusformat magnetfält på 5 µT eller inkoherent magnetfältbrus IMF med en maximal amplitud på 50 µT.Det verkar inte finnas någon signifikant förändring i S-100-koncentrationen i blod hos råttor som exponerats under 6 timmar för höga nivåer (4W) av kontinuerlig våg (CW) 915MHz mikrovågor, 50Hz sinusformade magnetfält (5µT) och osammanhängande magnetfält (IMF) vid 50µT. Däremot indikerar resultaten av den kombinerade exponeringen CW + IMF en minskad koncentration av S100 i blod.Minskningen överensstämmer med resultaten av en undersökning under 2010 att de extremt lågfrekventa (ELF) magnetfälten från fläktmotorn (50Hz AC, 0,3-1,5 T) minskade det förväntade BBB-läckaget av albumin på grund av mikrovågsexponering .Resultaten från andra studier indikerar också att bioeffekter orsakade av exponering för mikrovågor reduceras genom överläggning med extremt lågfrekventa magnetfält ELF. Det är därför av yttersta vikt när man undersöker bioeffekter från mikrovågor för att också kontrollera nivåer och frekvenser av lågfrekventa magnetfält i omgivningen, vilket kan vara en av anledningarna till den breda spridningen i de rapporterade resultaten