Scaling of human behavior during portal browsing

We investigate transitions of portals users between different subpages. A weighted network of portals subpages is reconstructed where edge weights are numbers of corresponding transitions. Distributions of link weights and node strengths follow power laws over several decades. Node strength increases faster than linearly with node degree. The distribution of time spent by the user at one subpage decays as power law with exponent around 1.3. Distribution of numbers P(z) of unique subpages during one visit is exponential. We find a square root dependence between the average z and the total number of transitions n during a single visit. Individual path of portal user resembles of self-attracting walk on the weighted network. Analytical model is developed to recover in part the collected data.Comment: 6 pages, 7 figure

Site-Directed Mutagenesis of the Cysteine Ligands to the [4Fe−4S] Cluster of Escherichia coli MutY †

International audienceThe Escherichia coli DNA repair enzyme MutY plays an important role in the recognition and repair of 7,8-dihydro-8-oxo-2′-deoxyguanosine:2′-deoxyadenosine (OG:A) mismatches in DNA [Michaels et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 7022-7025]. MutY prevents DNA mutations resulting from the misincorporation of A opposite OG by using N-glycosylase activity to remove the adenine base. An interesting feature of MutY is that it contains a [4Fe-4S] 2+ cluster that has been shown to play an important role in substrate recognition [Porello, S. L., Cannon, M. J., David, S. S. (1998) Biochemistry 37, 6465-6475]. Herein, we have used site-directed mutagenesis to individually replace the cysteine ligands to the [4Fe-4S] 2+ cluster of E. coli MutY with serine, histidine, and alanine. The extent to which the various mutations reduce the levels of protein overexpression suggests that coordination of the [4Fe-4S] 2+ cluster provides stability to MutY in vivo. The ability of the mutated enzymes to bind to a substrate analogue DNA duplex and their in vivo activity were evaluated. Remarkably, the effects are both substitution and position dependent. For example, replacement of cysteine 199 with histidine provides a mutated enzyme that is expressed at high levels and exhibits DNA binding and in vivo activity similar to the WT enzyme. These results suggest that histidine coordination to the iron-sulfur cluster may be accommodated at this position in MutY. In contrast, replacement of cysteine 192 with histidine results in less efficient DNA binding and in vivo activity compared to the WT enzyme without affecting levels of overexpression. The results from the site-directed mutagenesis suggest that the structural properties of the iron-sulfur cluster coordination domain are important for both substrate DNA recognition and the in vivo activity of MutY

Collective emotions online and their influence on community life

E-communities, social groups interacting online, have recently become an object of interdisciplinary research. As with face-to-face meetings, Internet exchanges may not only include factual information but also emotional information - how participants feel about the subject discussed or other group members. Emotions are known to be important in affecting interaction partners in offline communication in many ways. Could emotions in Internet exchanges affect others and systematically influence quantitative and qualitative aspects of the trajectory of e-communities? The development of automatic sentiment analysis has made large scale emotion detection and analysis possible using text messages collected from the web. It is not clear if emotions in e-communities primarily derive from individual group members' personalities or if they result from intra-group interactions, and whether they influence group activities. We show the collective character of affective phenomena on a large scale as observed in 4 million posts downloaded from Blogs, Digg and BBC forums. To test whether the emotions of a community member may influence the emotions of others, posts were grouped into clusters of messages with similar emotional valences. The frequency of long clusters was much higher than it would be if emotions occurred at random. Distributions for cluster lengths can be explained by preferential processes because conditional probabilities for consecutive messages grow as a power law with cluster length. For BBC forum threads, average discussion lengths were higher for larger values of absolute average emotional valence in the first ten comments and the average amount of emotion in messages fell during discussions. Our results prove that collective emotional states can be created and modulated via Internet communication and that emotional expressiveness is the fuel that sustains some e-communities.Comment: 23 pages including Supporting Information, accepted to PLoS ON

Heavy metal composition in the Plantago major L. from center of the Murmansk City, Kola Peninsula, Russia

Plantago major is an indicator of environmental pollution in the city. The plant grows along the traversed paths, close to the sidewalks. Contaminating substances accumulate on the leaves of the plantain. In the summer of 2016, samples of plants were collected in the central Murmansk region for analysis using a scanning electron microscope to identify dust particles on their surface, and to study leaves using the ICP-MS method to determination of heavy metals content. A relatively serious concentration of lead, zinc, copper, nickel as well as high arsenic and chromium content has been demonstrated in the city center, along with ties with human activities (vehicular traffic). High iron content is associated with peat soils used in the city for fertilization. The remaining metal content is relatively low

Heavy metal composition in the Plantago major L. from center of the Murmansk City, Kola Peninsula, Russia

Plantago major is an indicator of environmental pollution in the city. The plant grows along the traversed paths, close to the sidewalks. Contaminating substances accumulate on the leaves of the plantain. In the summer of 2016, samples of plants were collected in the central Murmansk region for analysis using a scanning electron microscope to identify dust particles on their surface, and to study leaves using the ICP-MS method to determination of heavy metals content. A relatively serious concentration of lead, zinc, copper, nickel as well as high arsenic and chromium content has been demonstrated in the city center, along with ties with human activities (vehicular traffic). High iron content is associated with peat soils used in the city for fertilization. The remaining metal content is relatively low. DOI: http://dx.doi.org/10.5281/zenodo.146106

ПРОЕКТНО-ОРІЄНТОВАНЕ УПРАВЛІННЯ ПРОЦЕСАМИ РОЗВИТКУ ДУАЛЬНИХ СИСТЕМ

Approaches to ensure an adequate level of life safety in the border areas of neighboring countries in terms of intensification of interstate relations are proposed. The importance of the establishment and execution of cross-border operative-rescue units for emergency response is shown. Performance features of dual system «transboundary operative-rescue units - emergency situation» involving methods and tools of project-oriented management are identified. The influence of external and internal factors in order to improve the level efficiency of international units is analyzed. The main directions of improving the relationship between the elements of the dual system are systematized. Modeling approaches showing the influence of project-oriented management methodology on the dual system of «transboundary operative-rescue units - emergency situation» are developed. On the basis of applied geometry the model example of the interaction of two principles of the dual system «transboundary operative-rescue units - emergency situation», taking into account the impact of means and methods of project-oriented management is proposed. The analysis of equilibrium point movement of dual system with different coefficient data of changes in the environment of transboundary operative-rescue units and intensity of emergencies is made.Запропоновано підходи до забезпечення належного рівня безпеки життєдіяльності на прикордонних територіях суміжних держав в умовах інтенсифікації рівня розвитку міждержавних зв’язків. Показана важливість створення та функціонування транскордонних оперативно-рятувальних підрозділів для ліквідації надзвичайних ситуацій. Розглянуті особливості функціонування дуальної системи «транскордонні оперативно-рятувальні підрозділи – надзвичайні ситуації» із залученням методів та засобів проектно-орієнтованого управління. Проаналізовано вплив зовнішніх та внутрішніх чинників на підвищення результативності діяльності міждержавних формувань. Систематизовано основні напрямки удосконалення взаємозв’язків між елементами досліджуваної дуальної системи. Розроблено підходи до моделювання і аналізу впливу проектно-орієнтованої методології управління на діяльність дуальної системи «транскордонні оперативно-рятувальні підрозділи - надзвичайні ситуації». На засадах використання положень прикладної геометрії запропоновано приклад модельної реалізації процесу взаємодії двох начал дуальної системи «транскордонні оперативно-рятувальні підрозділи - надзвичайні ситуації» із урахуванням впливу засобів і методів проектно-орієнтованого управління. Проведений аналізпереміщення у фазовому просторі точки рівноваги дуальної системи при різних коефіцієнтах зміни в середовищі рівня ресурсної забезпеченості транскордонних оперативно-рятувальних підрозділів та інтенсивності надзвичайних ситуацій

A Fast Algorithm Finding the Shortest Reset Words

In this paper we present a new fast algorithm finding minimal reset words for finite synchronizing automata. The problem is know to be computationally hard, and our algorithm is exponential. Yet, it is faster than the algorithms used so far and it works well in practice. The main idea is to use a bidirectional BFS and radix (Patricia) tries to store and compare resulted subsets. We give both theoretical and practical arguments showing that the branching factor is reduced efficiently. As a practical test we perform an experimental study of the length of the shortest reset word for random automata with $n$ states and 2 input letters. We follow Skvorsov and Tipikin, who have performed such a study using a SAT solver and considering automata up to $n=100$ states. With our algorithm we are able to consider much larger sample of automata with up to $n=300$ states. In particular, we obtain a new more precise estimation of the expected length of the shortest reset word $\approx 2.5\sqrt{n-5}$.Comment: COCOON 2013. The final publication is available at http://link.springer.com/chapter/10.1007%2F978-3-642-38768-5_1

Using a runway paradigm to assess the relative strength of rats' motivations for enrichment objects

Laboratory animals should be provided with enrichment objects in their cages; however, it is first necessary to test whether the proposed enrichment objects provide benefits that increase the animals’ welfare. The two main paradigms currently used to assess proposed enrichment objects are the choice test, which is limited to determining relative frequency of choice, and consumer demand studies, which can indicate the strength of a preference but are complex to design. Here, we propose a third methodology: a runway paradigm, which can be used to assess the strength of an animal’s motivation for enrichment objects, is simpler to use than consumer demand studies, and is faster to complete than typical choice tests. Time spent with objects in a standard choice test was used to rank several enrichment objects in order to compare with the ranking found in our runway paradigm. The rats ran significantly more times, ran faster, and interacted longer with objects with which they had previously spent the most time. It was concluded that this simple methodology is suitable for measuring rats’ motivation to reach enrichment objects. This can be used to assess the preference for different types of enrichment objects or to measure reward system processes

Trends in Decline of Antiretroviral Resistance among ARV-Experienced Patients in the HIV Outpatient Study: 1999–2008

Background. Little is known about temporal trends in frequencies of clinically relevant ARV resistance mutations in HIV strains from U.S. patients undergoing genotypic testing (GT) in routine HIV care. Methods. We analyzed cumulative frequency of HIV resistance among patients in the HIV Outpatient Study (HOPS) who, during 1999–2008 and while prescribed antiretrovirals, underwent GT with plasma HIV RNA >1,000 copies/mL. Exposure ≥4 months to each of three major antiretroviral classes (NRTI, NNRTI and PI) was defined as triple-class exposure (TCE). Results. 906 patients contributed 1,570 GT results. The annual frequency of any major resistance mutations decreased during 1999–2008 (88% to 79%, P = 0.05). Resistance to PIs decreased among PI-exposed patients (71% to 46%, P = 0.010) as exposure to ritonavir-boosted PIs increased (6% to 81%, P < 0.001). Non-significant declines were observed in resistance to NRTIs among NRTI-exposed (82% to 67%), and triple-class-resistance among TCE patients (66% to 41%), but not to NNRTIs among NNRTI-exposed. Conclusions. HIV resistance was common but declined in HIV isolates from subgroups of ARV-experienced HOPS patients during 1999–2008. Resistance to PIs among PI-exposed patients decreased, possibly due to increased representation of patients whose only PI exposures were to boosted PIs