Integrating personality research and animal contest theory: aggressiveness in the green swordtail <i>Xiphophorus helleri</i>

&lt;p&gt;Aggression occurs when individuals compete over limiting resources. While theoretical studies have long placed a strong emphasis on context-specificity of aggression, there is increasing recognition that consistent behavioural differences exist among individuals, and that aggressiveness may be an important component of individual personality. Though empirical studies tend to focus on one aspect or the other, we suggest there is merit in modelling both within-and among-individual variation in agonistic behaviour simultaneously. Here, we demonstrate how this can be achieved using multivariate linear mixed effect models. Using data from repeated mirror trials and dyadic interactions of male green swordtails, &lt;i&gt;Xiphophorus helleri&lt;/i&gt;, we show repeatable components of (co)variation in a suite of agonistic behaviour that is broadly consistent with a major axis of variation in aggressiveness. We also show that observed focal behaviour is dependent on opponent effects, which can themselves be repeatable but were more generally found to be context specific. In particular, our models show that within-individual variation in agonistic behaviour is explained, at least in part, by the relative size of a live opponent as predicted by contest theory. Finally, we suggest several additional applications of the multivariate models demonstrated here. These include testing the recently queried functional equivalence of alternative experimental approaches, (e. g., mirror trials, dyadic interaction tests) for assaying individual aggressiveness.&lt;/p&gt

Morphology and Formation of an Holocene Coastal Dune Field, Bruce Peninsula, Ontario

This paper describes a dune field on the gently-sloping Lake Huron shoreline of the Bruce Peninsula, Ontario. The inland boundary is marked by a prominent dune ridge 60 m wide and up to 30 m high, which extends parallel to the shoreline for about 19 km, and was formed about 5000 years BP near the end of the Nipissing transgression. The islands and rock reefs which protect the modern shoreline were submerged under the higher lake levels, giving rise to a relatively straight, exposed beach from which sediment was supplied for building the dune ridge. Dunes formed between this ridge and the modern shoreline during the post-Nipissing regression decrease in height and continuity, reflecting decreased sediment supply associated with regression and reduced wave exposure as the offshore islands emerged. The sequence described here supports previous conclusions that transgressions are associated with periods of coastal dune formation and instability.On fait ici la description d'un champ de dunes situé sur le rivage faiblement incliné de la péninsule de Bruce, au lac Huron. La limite intérieure est caractérisée par une chaîne de dunes de 60 m de large et jusqu'à 30 m de haut qui s'étend parallèlement au rivage sur une longueur de 19 km; elle a été formée il y a 5000 ans BP, presque la fin de la transgression de Nipissing. Les îles et les écueils rocheux qui protègent le rivage actuel étaient alors immergés sous des niveaux lacustres supérieurs, permettant ainsi la formation d'une plage découverte relativement rectiligne qui a fourni le sable nécessaire à l'édification de la chaîne de dunes. La formation, au cours de la régression post-Nipissing, de dunes moins hautes et plus dispersées, entre la chaîne de dunes et le rivage actuel, témoigne d'une faible alimentation en sédiments associée à la régression et d'une moindre exposition aux vagues en raison de l'émersion des îles. La séquence décrite ici corroborent les conclusions antérieures selon lesquelles les transgressions correspondent à des périodes de formation et d'instabilité des dunes littorales.Dieser Aufsatz beschreibt ein Dùnenfeld, das am schwach abfallenden Ufer des Huron-Sees, Bruce-Halbinsel liegt. Die Grenze zum Landinnern ist hervorgehoben durch eine Kette von Dunen, die 60 m breit und bis zu 30 m hoch sind, und die sich parallel zum Ufer ùber eine Lange von 19 km ausdehnt; sie wurde vor 5000 Jahren v.u.Z. gebildet, fast am Ende der Transgression von Nipissing. Die Insein und die Felsklippen, die das heutige Ufer schùtzen, waren damais unter den hôheren Seen-Niveaus untergetaucht, so dass ein offener, relativ gerader Strand entstehen konnte, der den fur den Aufbau der Dunenkette notwendigen Sand lieferte. Wàhrend der Regression post-Nipissing haben sich zwischen der Dunenkette und dem heutigen Uferweniger hohe und mehr verstreute Dùnen gebildet, welche Zeugnis von einer schwachen Sediment-Zufuhr abgeben, in Verbindung mit der Regression und einem geringeren Einfluss der Wellen wegen des Auftauchens der Insein. Die hier beschriebene Sequenz bestàtigt frùhere Schlussfolgerungen. denen zufolge die Transgressionen mit Perioden der Bildung und Instabilitàt von Kùstendùnen in Verbindung gebracht werden

Shaping electron wave functions in a carbon nanotube with a parallel magnetic field

A magnetic field, through its vector potential, usually causes measurable changes in the electron wave function only in the direction transverse to the field. Here we demonstrate experimentally and theoretically that in carbon nanotube quantum dots, combining cylindrical topology and bipartite hexagonal lattice, a magnetic field along the nanotube axis impacts also the longitudinal profile of the electronic states. With the high (up to 17T) magnetic fields in our experiment the wave functions can be tuned all the way from "half-wave resonator" shape, with nodes at both ends, to "quarter-wave resonator" shape, with an antinode at one end. This in turn causes a distinct dependence of the conductance on the magnetic field. Our results demonstrate a new strategy for the control of wave functions using magnetic fields in quantum systems with nontrivial lattice and topology.Comment: 5 figure

Primary and secondary contributions to aerosol light scattering and absorption in Mexico City during the MILAGRO 2006 campaign

A photoacoustic spectrometer, a nephelometer, an aethalometer, and an aerosol mass spectrometer were used to measure at ground level real-time aerosol light absorption, scattering, and chemistry at an urban site located in North East Mexico City (Instituto Mexicano del Petroleo, Mexican Petroleum Institute, denoted by IMP), as part of the Megacity Impact on Regional and Global Environments field experiment, MILAGRO, in March 2006. Photoacoustic and reciprocal nephelometer measurements at 532 nm accomplished with a single instrument compare favorably with conventional measurements made with an aethalometer and a TSI nephelometer. The diurnally averaged single scattering albedo at 532 nm was found to vary from 0.60 to 0.85 with the peak value at midday and the minimum value at 07:00 a.m. local time, indicating that the Mexico City plume is likely to have a net warming effect on local climate. The peak value is associated with strong photochemical generation of secondary aerosol. It is estimated that the photochemical production of secondary aerosol (inorganic and organic) is approximately 75% of the aerosol mass concentration and light scattering in association with the peak single scattering albedo. A strong correlation of aerosol scattering at 532 nm and total aerosol mass concentration was found, and an average mass scattering efficiency factor of 3.8 m&lt;sup&gt;2&lt;/sup&gt;/g was determined. Comparisons of photoacoustic and aethalometer light absorption with oxygenated organic aerosol concentration (OOA) indicate a very small systematic bias of the filter based measurement associated with OOA and the peak aerosol single scattering albedo

Event‐scale dynamics of a parabolic dune and its relevance for mesoscale evolution

Parabolic dunes are wide-spread aeolian landforms found in a variety of environments. Despite modelling advances and good understanding of how they evolve, there is limited empirical data on their dynamics at short time-scales of hours, and on how these dynamics relate to their medium-term evolution. This study presents the most comprehensive dataset to date on aeolian processes (airflow and sediment transport) inside a parabolic dune at an event-scale. This is coupled with information on elevation changes inside the landform to understand its morphological response to a single wind event. Results are contextualized against the medium-term (years) allowing us to investigate one of the most persistent conundrums in geomorphology, that of the significance of short-term findings for landform evolution. Our field data suggested three key findings: 1) sediment transport rates inside parabolic dunes correlate well with wind speeds rather than turbulence; 2) up to several tonnes of sand can move through these landforms in a few hours; 3) short-term elevation changes inside parabolic dunes can be complex and different from long-term net spatial patterns, including simultaneous erosion and accumulation along the same wall. Modeled airflow patterns along the basin were similar to those measured in situ for a range of common wind directions, demonstrating the potential for strong transport during multiple events. Meso-scale analyses suggested that the measured event was representative of the type of events potentially driving significant geomorphic changes over years, with supply-limiting conditions playing an important role in resultant flux amounts

Spectral light absorption by ambient aerosols influenced by biomass burning in the Amazon Basin. I: Comparison and field calibration of absorption measurement techniques

International audienceSpectral aerosol light absorption is an important parameter for the assessment of the radiation budget of the atmosphere. Although on-line measurement techniques for aerosol light absorption, such as the Aethalometer and the Particle Soot Absorption Photometer (PSAP), have been available for two decades, they are limited in accuracy and spectral resolution because of the need to deposit the aerosol on a filter substrate before measurement. Recently, a 7-wavelength (?) Aethalometer became commercially available, which covers the visible (VIS) to near-infrared (NIR) spectral range (?=450?950 nm), and laboratory calibration studies improved the degree of confidence in these measurement techniques. However, the applicability of the laboratory calibration factors to ambient conditions has not been investigated thoroughly yet. As part of the LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia ? SMOke aerosols, Clouds, rainfall and Climate) campaign from September to November 2002 in the Amazon basin we performed an extensive field calibration of a 1-? PSAP and a 7-? Aethalometer utilizing a photoacoustic spectrometer (PAS, 532 nm) as reference device. Especially during the dry period of the campaign, the aerosol population was dominated by pyrogenic emissions. The most pronounced artifact of integrating-plate type attenuation techniques (e.g. Aethalometer, PSAP) is due to multiple scattering effects within the filter matrix. For the PSAP, we essentially confirmed the laboratory calibration factor by Bond et al. (1999). On the other hand, for the Aethalometer we found a multiple scattering enhancement of 5.23 (or 4.55, if corrected for aerosol scattering), which is significantly larger than the factors previously reported (~2) for laboratory calibrations. While the exact reason for this discrepancy is unknown, the available data from the present and previous studies suggest aerosol mixing (internal versus external) as a likely cause. For Amazonian aerosol, we found no absorption enhancement due to hygroscopic particle growth in the relative humidity (RH) range between 40% and 80%. However, a substantial bias in PSAP sensitivity that correlated with both RH and temperature (T) was observed for 20%RH<30% and 24°

Look Who’s Talking:Using creative, playful arts-based methods in research with young children

Young children are often ignored or marginalised in the drive to address children’s participation and their wider set of rights. This is the case generally in social research, as well as within the field of Arts-Based Education Research. This article contributes to the growing literature on young children’s involvement in arts-based research, by providing a reflective account of our learning and playful engagement with children using creative methods. This small pilot project forms part of a larger international project titled Look Who’s Talking: Eliciting the Voices of Children from Birth to Seven, led by Professor Kate Wall at the University of Strathclyde. Visiting one nursery in Scotland, we worked with approximately 30 children from 3 to 5 years old. Seeking to connect with their play-based nursery experiences, we invited children to participate in a range of arts-based activities including drawing, craft-making, sculpting, a themed ‘play basket’ with various props, puppetry and videography. In this article, we develop reflective, analytical stories of our successes and dilemmas in the project. We were keen to establish ways of working with children that centred their own creativity and play, shaped by the materials we provided but not directed by us. However, we struggled to balance our own agenda with the more open-ended methods we had used. We argue that an intergenerational approach to eliciting voice with young children – in which adults are not afraid to shape the agenda, but do so in responsive, gradual and sensitive ways – creates the potential for a more inclusive experience for children that also meets researcher needs

Factors affecting the implementation of an elementary science curriculum in three northern Saskatchewan provincial schools

This qualitative study explores factors affecting the implementation of an elementary science curriculum in three schools in northern Saskatchewan. Data gathered from thirteen elementary level teachers indicate that most teachers interviewed possess a general vision of ideal science teaching and learning close to that presented in the provincial curriculum, but that most teachers believe that they are a considerable distance away from translating that vision into reality. Data indicate that few teachers use the curriculum on a regular basis or possess detailed familiarity with its components.A variety of generic factors not unique to the north are creating challenges for teachers striving to implement the science curriculum. Tight timelines for implementation, as well as challenges such as class size, limited inservice availability, and infrequent networking opprtunities were identified as challenges. Many challenges were linked to the need to refine or acquire skills made more necessary by new curricula, as well as by other provincial and regional initiatives. The need to address such skill deficits is felt by most teachers, but is felt most acutely by those who are not recent graduates of teacher-training programs or those who rely primarily on locally available professional development within the context of the regular school year and setting.Teachers in this study indicated that a greater degree of instructional leadership at the school division and school level would assist them in their efforts to implement mandated changes. Concern was also expressed that little monitoring of the implementation process by either their school division or by the provincial government had taken place.A variety of factors unique to the North were identified as affecting implementation efforts. Teachers found the curriculum to be easily adapted for northern needs, as well as appropriate for students for whom English is a second language. General funding levels and special school division initiatives were also seen as helpful. Respondents, however, identified socioeconomic factors, questionable levels of instructional leadership, as well as distance between community and school as serious challenges to implementation.This study confirms current research indicating that managing changes such as the implementation of an elementary science curriculum is a complex venture necessitating organizational and operational changes at school, school division, and provincial levels to encourage and support efforts to make schools learning organizations for both students and teachers. The study concludes with several recommended areas of further research, as well as with several specific action recommendations to assist with the implementation of new curricula

Pathological and ecological host consequences of infection by an introduced fish parasite

The infection consequences of the introduced cestode fish parasite Bothriocephalus acheilognathi were studied in a cohort of wild, young-of-the-year common carp Cyprinus carpio that lacked co-evolution with the parasite. Within the cohort, parasite prevalence was 42% and parasite burdens were up to 12% body weight. Pathological changes within the intestinal tract of parasitized carp included distension of the gut wall, epithelial compression and degeneration, pressure necrosis and varied inflammatory changes. These were most pronounced in regions containing the largest proportion of mature proglottids. Although the body lengths of parasitized and non-parasitized fish were not significantly different, parasitized fish were of lower body condition and reduced weight compared to non-parasitized conspecifics. Stable isotope analysis (δ15N and δ13C) revealed trophic impacts associated with infection, particularly for δ15N where values for parasitized fish were significantly reduced as their parasite burden increased. In a controlled aquarium environment where the fish were fed ad libitum on an identical food source, there was no significant difference in values of δ15N and δ13C between parasitized and non-parasitized fish. The growth consequences remained, however, with parasitized fish growing significantly slower than non-parasitized fish, with their feeding rate (items s−1) also significantly lower. Thus, infection by an introduced parasite had multiple pathological, ecological and trophic impacts on a host with no experience of the parasite