Human management of a robotic swarm

This paper proposes a management algorithm that allows a human operator to organize a robotic swarm via a robot leader. When the operator requests a robot to become a leader, nearby robots suspend their activities. The operator can then request a count of the robots, and assign them into subgroups, one for each task. Once the operator releases the leader, the robots perform the tasks they were assigned to. We report a series of experiments conducted with up to 30 e-puck mobile robots. On average, the counting and allocation algorithm correctly assigns 95 % of the robots in the swarm. The time to count the number of robots increases, on average, linearly with the number of robots, provided they are arranged in random formation

Putting pharmaceuticals into the wider context of challenges to fish populations in rivers

The natural range of fish species in our rivers is related to flow, elevation, temperature, local habitat and connectivity. For over 2000 years, humans have altered to varying degrees the river habitat. In the past 200 years, we added to the environmental disruption by discharging poorly treated sewage, nutrients and industrial waste into our rivers. For many rivers, the low point arrived during the period of 1950s–1970s, when rapid economic development overrode environmental concerns and dissolved oxygen concentrations dropped to zero. In these more enlightened times, gross river pollution is a thing of the past in the Developed World. However, persistent legacy chemical contaminants can be found in fish long after their discharge ceased. Changes in habitat quality and morphology caused and continue to cause the disappearance of fish species. The range of fish stressors has now increased as temperatures rise, and non-native fish introductions bring new diseases. The threat from pharmaceuticals to fish populations remains hypothetical, and no studies have yet linked change in fish populations to exposure

Prevalence of pain flashbacks in post-traumatic stress disorder arising from exposure to multiple traumas or childhood traumatization

Background: Flashbacks are a form of multisensory memory that are experienced with a ‘happening in the present’ quality. Pain flashbacks are a re-experiencing of pain felt at the time of a traumatic event. It is unclear how common pain flashbacks are. Aims: The current study was designed primarily to assess the prevalence of pain flashbacks in a sample of patients with post-traumatic stress disorder (PTSD). Methods: We assessed the prevalence of pain flashbacks over a period of two years in patients (n = 166) referred to a psychological trauma service in the UK. Patients underwent a clinical screen for PTSD, and completed a self-report measure of pain flashbacks. Results: Pain flashbacks were classified as present in 49% of a sample of complex trauma patients meeting criteria for PTSD. Pain flashbacks were positively associated with the extent of pain at the time of trauma. Conclusions: Pain re-experiencing in PTSD, and its relative absence in non-clinical populations, supports an account of memory in which perceptual details can be re- experienced when memories have been encoded under conditions of extreme stress. It may be possible to conceptualize some cases of unexplained pain as pain flashbacks, or of having a trauma origin

Sex-specific effects of gender identification on pain study recruitment

Epidemiological, clinical and laboratory studies show sex differences in pain responses, with women more sensitive to nociceptive stimulation and more vulnerable to long term pain conditions than men. Given evidence that males are culturally reinforced for the ability to endure (or under-report) pain, some of these findings might be explained by socio-cultural beliefs about gender-appropriate behaviour. One potential manifestation of these effects might be differential participation in pain studies, with males adhering to stereotypical masculine roles viewing participation as a way to demonstrate their masculinity. To test this possibility, we assessed gender identification in 137 healthy participants. At the end of the assessment, they were asked if they would like to participate in other research studies. Interested participants were then asked to participate in a study involving administration of pain-evoking stimulation. We compared individuals who agreed to participate in the pain study to those who declined. We observed a significant sex by participation interaction in masculine gender identification, such that males (but not females) who agreed to participate identified significantly more with masculine gender. Among masculine gender traits examined, we found that high levels of aggression and competitiveness were the strongest predictors of pain study participation. Our results suggest that male samples in pain studies might have higher levels of masculine gender identification than the wider male population. Taken together with previous findings of lower pain sensitivity (or reporting) in masculine-identifying males, these results suggest an explanation for some of the sex-related differences observed in pain responses. Perspective : To examine whether sex and gender affect willingness to participate in pain studies, we assessed gender identification in male and female participants, then attempted to recruit them to participate in a pain study. Males who agree to participate in pain studies are significantly higher in masculine gender identification than males who decline to participate or females who agree to participate. Males who agreed to participate were particularly high in aggressiveness and competitiveness

Factors affecting metal mobilisation during oxidation of sulphidic, sandy wetland substrates

Most metals accumulate as sulphides under anoxic conditions in wetland substrates, reducing their bioavailability due to the solubility of metal sulphides. However, upon oxidation of these sulphides when the substrate is occasionally oxidised, metals can be released from the solid phase to the pore water or overlaying surface water. This release can be affected by the presence of carbonates, organic matter and clay. We compared changes of Cd, Cu and Zn mobility (CaCl2 extraction) during oxidation of a carbonate-rich and a carbonate-poor sulphidic, sandy wetland substrate. In addition, we studied how clay with low and high cation sorption capacity (bentonite and kaolinite, respectively) and organic matter (peat) can counteract Cd, Cu and Zn release during oxidation of both carbonate-rich and carbonate-poor sulphidic sediments. CaCl2-extractability of Cu, a measure for its availability, is low in both carbonate-poor and carbonate-rich substrates, whereas its variability is high. The availability of Cd and Zn is much higher and increases when peat is supplied to carbonate-poor substrates. A strong reduction of Cd and Zn extractability is observed when clay is added to carbonate-poor substrates. This reduction depends on the clay type. Most observations could be explained taking into account pH differences between treatments, with kaolinite resulting in a lower pH in comparison to bentonite. These pH differences affect the presence and characteristics of dissolved organic carbon and the metal speciation, which in turns affects the interaction of metals with the solid soil phase. In carbonate-rich substrates, Cd and Zn availability is lower and the effects of peat and clay amendment are less clear. The latter can also be attributed to the high pH and lack of pH differences between treatments

INTERATION OF HERBICIDS AND SEASONING LEAVES ON CORN HYBRIDS

O objetivo do trabalho foi avaliar os efeitos da aplicação de diferentes herbicidas em pós-emergência e época de adubação via foliar sobre híbridos de milho. O experimento foi conduzido na Fazenda Escola da UEPG, Ponta Grossa/PR, delineado em blocos casualizados com 4 repetições. Os tratamentos constaram de três níveis do fator herbicida mesotrione (120 gha-1); atrazine (1250 g ha-1) e mesotrione + atrazine; dois híbridos (30P70 e 30K75), duas épocas de aplicação de adubo foliar [0 e 7 dias após aplicação dos herbicidas (DAA)]. Avaliou-se a altura de plantas, número de folhas por planta, diâmetro de colmo, teor de clorofila e variáveis da produtividade. Detectou-se interação entre herbicidas e híbridos para número de folhas por planta aos 32 DAA, entre herbicidas e época de aplicação do adubo foliar para diâmetro de colmo aos 32 DAA, entre híbridos e épocas de aplicação do adubo foliar para grãos por fileira. O híbrido 30P70 apresentou melhor desempenho quanto à altura de planta, de inserção da primeira espiga, número de espigas por planta e grãos por fileira e pior quanto à fitomassa de 1000 grãos, diâmetro e tamanho de espiga quando comparado ao 30K75. O diâmetro de espiga foi maior quando da aplicação de mesotrione e o tamanho da espiga quando da aplicação da mistura mesotrione + atrazine. Não houve interações entre herbicidas, épocas de aplicação do adubo foliar e híbridos de milho em relação à aplicação dos herbicidas para as variáveis da produtividade

Influence of oxygen ordering kinetics on Raman and optical response in YBa_2Cu_3O_{6.4}

Kinetics of the optical and Raman response in YBa_2Cu_3O_{6.4} were studied during room temperature annealing following heat treatment. The superconducting T_c, dc resistivity, and low-energy optical conductivity recover slowly, implying a long relaxation time for the carrier density. Short relaxation times are observed for the B_{1g} Raman scattering -- magnetic, continuum, and phonon -- and the charge transfer band. Monte Carlo simulations suggest that these two relaxation rates are related to two length scales corresponding to local oxygen ordering (fast) and long chain and twin formation (slow).Comment: REVTeX, 3 pages + 4 PostScript (compressed) figure

Functional architecture and specifications for Tolerancing Data and Knowledge Management

Part 1: Knowledge ManagementInternational audienceThe paper deals with the Computer-Aided Tolerancing and Product Data Management. It is especially focus on data and knowledge management system to support and improve the tolerancing tasks in product development process. The first part of the paper introduces an overview about the recent developments related to tolerancing supports and data management systems. Based on a literature survey and industrial issues, the second part proposes a functional architecture and specifications of the data and knowledge manage-ment system addressing the numerous needs clarified by tolerancing experts

Nitrogen source apportionment for the catchment, estuary and adjacent coastal waters of the Scheldt.

Using the systems approach framework (SAF), a coupled model suite was developed for simulating land-use decision making in response to nutrient abatement costs and water and nutrient fluxes in the hydrological network of the Scheldt River, and nutrient fluxes in the estuary and adjacent coastal sea. The purpose was to assess the efficiency of different long-term water quality improvement measures in current and future climate and societal settings, targeting nitrogen (N) load reduction. The spatial-dynamic model suite consists of two dynamically linked modules: PCRaster is used for the drainage network and is combined with ExtendSim modules for farming decision making and estuarine N dispersal. Model predictions of annual mean flow and total N concentrations compared well with data available for river and estuary (r² ≥ 0.83). Source apportionment was carried out to societal sectors and administrative regions; both households and agriculture are the major sources of N, with the regions of Flanders and Wallonia contributing most. Load reductions by different measures implemented in the model were comparable (~75% remaining after 30 yr), but costs differed greatly. Increasing domestic sewage connectivity was more effective, at comparatively low cost (47% remaining). The two climate scenarios did not lead to major differences in load compared with the business-as-usual scenario (~88% remaining). Thus, this spatially explicit model of water flow and N fluxes in the Scheldt catchment can be used to compare different long-term policy options for N load reduction to river, estuary, and receiving sea in terms of their effectiveness, cost, and optimal location of implementation