Intrinsically stable light source at telecom wavelengths

We present a highly stable light source at telecom wavelengths, based on a short erbium doped fiber. The high stability arises from the high inversion of the Er3+ion population. This source is developed to work as a stable reference in radiometric applications and is useful in any application where high stability and/or a large bandwidth are necessary. The achieved long-term stability is 10 ppm

Measuring absolute spectral radiance using an Erbium Doped Fibre Amplifier

We describe a method to measure the spectral radiance of a source in an absolute way without the need of a reference. Here we give the necessary detail to allow for the device to be reproduced from standard fiber-optic components. The device is suited for fiber-optic applications at telecom wavelengths and calibration of powermeters and spectrometers at light levels from 1nW to 1uW

Paving the paths towards reflexive social research: a symposium

In late 2009 thirty researchers from fifteen different countries gathered in Porto, Portugal, for a discussion-oriented workshop entitled “Paths towards reflexive sociology: Ethnography matters”. Although with very different social, academic and theoretical backgrounds, and with quite distinct research focuses and approaches, all participants shared an obvious interest in questioning their own practice, its social and political implications, the constraints set down by rigidly structured academic and professional universes, the social effects of their presence amoung the groups under study, and the theoretical, methodological and practical challenges brought on by a constantly changing social world. The aim was not so much to promote a scholarly debate on the “epistemology of social sciences” or on the “differences” between “positive” and “reflexive” science (Burawoy, 1998), than it was to create an opportunity for the sharing of the practical and many times unheeded ways trough which social researchers produce and perfect their “craft”.info:eu-repo/semantics/publishedVersio

Paving the paths towards reflexive social research: a symposium

In late 2009 thirty researchers from fifteen different countries gathered in Porto, Portugal, for a discussion-oriented workshop entitled “Paths towards reflexive sociology: Ethnography matters”. Although with very different social, academic and theoretical backgrounds, and with quite distinct research focuses and approaches, all participants shared an obvious interest in questioning their own practice, its social and political implications, the constraints set down by rigidly structured academic and professional universes, the social effects of their presence amoung the groups under study, and the theoretical, methodological and practical challenges brought on by a constantly changing social world. The aim was not so much to promote a scholarly debate on the “epistemology of social sciences” or on the “differences” between “positive” and “reflexive” science (Burawoy, 1998), than it was to create an opportunity for the sharing of the practical and many times unheeded ways trough which social researchers produce and perfect their “craft”.info:eu-repo/semantics/publishedVersio

The influence of the Sound scattering layers on the vertical behaviour of two mesopelagic sharks

As apex predators, large sharks sustain the structure and function of marine communities. However, due to the ever-increasing fishing pressure and their slow life-history traits, shark populations have drastically declined in the last decades. Thus, improved knowledge on shark movements is crucial to implement effective management actions to prevent biodiversity loss and the disruption of marine ecosystems. Vertical patterns of apex predators have regularly been associated with foraging behaviours, yet the direct connection with prey’s vertical distribution and availability is often missing. In the open ocean, large aggregations of zooplanktonic and micronektonic organisms produce two unique acoustical signatures known as sound scattering layers (SSLs), believed to be an essential food source for oceanic predators. The present study uses pop-up satellite archival transmitters data of 22 blue (Prionace glauca) and 17 shortfin mako sharks (Isurus oxyrinchus), tracked within the North Atlantic Ocean, to assess the SSLs influence on these species’ diel vertical migrations (DVM) and foraging patterns. The sharks’ vertical patterns followed the SSLs diel migrations, commonly exhibiting surface-oriented behaviour when daytime micronekton concentrations at the shallow scattering layer (SSL) were higher compared to the upper deep scattering layer (DSL). Also, both species seemed to use the SSLs as foraging grounds, yet, while the mako shark appeared to target non-migrant or semi-migrant prey at the DSL, the blue shark generally favoured higher micronekton concentrations. Nevertheless, temperature and oxygen levels limited the extent of the vertical movements and impact the time spent at depth, sometimes preventing the animals from reaching the DSL. Thus, considering the ongoing expansion of the oxygen minimum zones, some predators might lose access to highly energetic prey and subsequently decrease their fitness. The SSLs showed to affect the sharks’ vertical range and time spent at epipelagic waters, revealing a potential use to detect regions with increased fishing risk

Career Planning in Elite Soccer: The Mediating Role of Self-Efficacy, Career Goals, and Athletic Identity

This study proposed a model to examine the role of self-efficacy, career goals, and athletic identity (AI) on the career planning of elite soccer players. Two hundred and eighty-one elite soccer players (males) participated in this study. Means, SD, and bivariate correlations were calculated for the variables under analysis. The hypothesized effect of self-efficacy, career goals, and AI on career planning was tested using structural equation modeling (SEM). Results supported the adequacy of the proposed model in explaining the career planning. Career planning is positively influenced by the level of self-efficacy of players through the definition of career goals and is negatively influenced by the level of AI. At the same time, the self-efficacy of players through the definition of career goals positively influenced AI. These findings reinforce the important role of self-efficacy and career goals for the development of AI and career planning and at the same time the opposite relationship between AI and career planning. Thus, it is suggested that a balance on AI, maintaining high levels of self-efficacy and career goals, is required to improve the process of career planning and retirementinfo:eu-repo/semantics/publishedVersio

Entanglement Routing Based on Fidelity Curves for Quantum Photonics Channels

The quantum internet promises to extend entanglement correlations from nearby neighbors to any two nodes in a network. How to efficiently distribute entanglement over large-scale networks is still an open problem that greatly depends on the technology considered. In this work, we consider quantum networks composed of photonic channels characterized by a trade-off between the entanglement generation rate and fidelity. For such networks we look at the two following problems: the one of finding the best path to connect any two given nodes in the network bipartite entanglement routing, and the problem of finding the best starting node in order to connect three nodes in the network multipartite entanglement routing. We consider two entanglement distribution models: one where entangled qubit are distributed one at a time, and a flow model where a large number of entangled qubits are distributed simultaneously. We propose the use of continuous fidelity curves (i.e., entanglement generation fidelity vs rate) as the main routing metric. Combined with multi-objective path-finding algorithms, the fidelity curves describing each link allow finding a set of paths that maximize both the end-to-end fidelity and the entanglement generation rate. For the models and networks considered, we prove that the algorithm always converges to the optimal solution, and we show through simulation that its execution time grows polynomial with the number of nodes in the network. Our implementation grows with the number of nodes with a power between $1$ and $1.4$ depending on the network. This work paves the way for the development of path-finding algorithms for networks with complex entanglement distribution protocols, in particular for other protocols that exhibit a trade-off between generation fidelity and rate, such as repeater-and-purify protocols

Activity schedule and foraging in Protopolybia sedula (Hymenoptera, Vespidae)

Protopolybia sedula is a social swarming wasp, widely spread throughout many countries in the Americas, including most of Brazil. Despite its distribution, studies of its behavioral ecology are scarce. This study aimed to describe its foraging activity and relation to climatic variables in the city of Juiz de Fora in southeastern Brazil. Three colonies were under observation between 07:00 and 18:00 during April 2012, January 2013, and March 2013. Every 30 minutes, the number of foragers leaving and returning to the colony was registered along with air temperature and relative humidity. Activity began around 07:30¸ increased between 10:30 and 14:30, and ended around 18:30. A mean of 52.7 exits and 54 returns were measured every 30 minutes. The daily mean values were 1,107 ± 510.6 exits and 1,135 ± 854.8 returns. Only one colony showed a significant correlation between forager exits and temperature (rs = 0.8055; P \u3c 0.0001) and between exits and relative humidity (rs = -0.7441; P = 0.0001). This paper shows that climatic variables are likely to have little control on the foraging rhythm of P. sedula when compared to other species, suggesting the interaction of other external and internal factors as stimuli of species foraging behavio