Can filesharers be triggered by economic incentives? Results of an experiment

Illegal filesharing on the internet leads to considerable financial losses for artists and copyright owners as well as producers and sellers of music. Thus far, measures to contain this phenomenon have been rather restrictive. However, there are still a considerable number of illegal systems, and users are able to decide quite freely between legal and illegal downloads because the latter are still difficult to sanction. Recent economic approaches account for the improved bargaining position of users. They are based on the idea of revenue-splitting between professional sellers and peers. In order to test such an innovative business model, the study reported in this article carried out an experiment with 100 undergraduate students, forming five small peer-to-peer networks.The networks were confronted with different economic conditions.The results indicate that even experienced filesharers hold favourable attitudes towards revenue-splitting.They seem to be willing to adjust their behaviour to different economic conditions

Reproduction and longevity of the predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae) and its prey, Tetranychus urticae (Acari: Tetranychidae) on different host plants

The biological control of twos potted spider mites by the predator Phytoseiulus persimilis is usually unsuccessful on greenhouse tomato crops in British Columbia. Experiments were conducted to determine the influence of host plant on the longevity and reproduction of the predator, and on the suitability of twospotted spider mites as prey. Lifespan and reproduction of P. persimilis were lower on tomato leaves than on bean leaves but feeding on spider mites that had been reared on tomato or bean leaves had no effect on the reproduction or lifespan of P. persimilis. A strain of twospotted spider mites that came from an outbreak on a greenhouse tomato crop lived for shorter periods and laid fewer eggs when confined on tomato leaves than on bean leaves. A strain of twospotted spider mites that had been maintained on bean leaves was unable to reproduce on tomato leaves. Exudates from glandular hairs were toxic to P. persimilis. Glandular hairs are important in pest management on tomato crops. Their removal through breeding might make plants more susceptible to herbivores. Therefore it would be preferable to develop other methods for biological control of twospotted spider mites on tomato

Toward a Unified Genetic Map of Higher Plants, Transcending the Monocot-Dicot Divergence

Closely related (confamilial) genera often retain large chromosomal tracts in which gene order is colinear, punctuated by structural mutations such as inversions and translocations 1. To explore the possibility that conservation of gene order might extrapolate to more distantly related taxa, we first estimated an average structural mutation rate. Nine pairs of taxa, for which there exist both comparative genetic maps and plausible estimates of divergence time, showed an average of0.14 (±0.06) structural mutations per chromosome per million years of divergence (Myr; Table 1). This value is offered as a first approximation, acknowledging that refined comparative data and/or divergence estimates may impel revision

Avaliação da relação seca/produtividade agrícola em cenário de mudanças climáticas.

As mudanças climáticas alertam para um possível aumento de eventos meteorológicos extremos em todo o mundo, sendo crescente a preocupação de como o clima pode mudar o ambiente e afetar a produção das culturas agrícolas. Este estudo investiga a relação entre a produtividade agrícola e a seca em algumas mesorregiões do estado de Minas Gerais, em cenários de mudanças climáticas. Foram utilizados dados meteorológicos diários projetados pelo modelo ECHAM5/MPI-OM, para o período de 2008 a 2020 para o cenário A1B. Utilizou-se a metodologia da zona agroecológica (AEZ) para estimar a produtividade futura do milho. Empregou-se o índice de seca Z de Palmer em um modelo de regressão linear com a produtividade do milho estimada pela metodologia da AEZ. O desempenho dos modelos foi verificado por meio das estatísticas: coeficiente de determinação (r2), raiz do erro quadrático médio(RMSE), erro absoluto médio (MAE) e índice de concordância de Willmott (d). Os resultados do índice de concordância de Willmott variaram entre 0,48 e 0,90, e os valores de r2 foram pouco expressivos.Contudo, a produtividade estimada pela metodologia AEZ projetou maiores perdas na produtividade do milho devido a limitações por água para os anos agrícolas de 2008/2009, 2009/2010, 2014/2015,2018/2019 para as mesorregiões Triângulo/Alto Paranaíba, Central Mineira e Jequitinhonha

Survey of parasitoids and hyperparasitoids (Hymenoptera) of the green peach aphid, Myzus persicae and the foxglove aphid, Aulacorthum solani (Hemiptera: Aphididae) in British Columbia

We surveyed the parasitoids and hyperparasitoids of the green peach aphid, Myzus persicae, and the foxglove aphid, Aulacorthum solani in the lower Fraser Valley of British Columbia, Canada. Field surveys were conducted using isolated pepper plants, with aphids, as trap plants. Primary parasitoids recorded from field surveys were Aphidius ervi, A. matricariae, Praon gallicum, P. unicum, P. humulaphidis, Ephedrus californicus, Diaeretiella rapae, Monoctonus paulensis, Aphelinus abdominalis and A. asychis. Diaretiella rapae only emerged from green peach aphids, and Ephedrus californicus only emerged from foxglove aphids. Aphidius matricariae was the most abundant primary parasitoid species reared from both aphid species. Hyperparasitoid species collected belonged to the genera Dendrocerus, Asaphes, Alloxysta, Pachyneuron and Syrphophagous. In greenhouses, Dendrocerus carpenteri was the dominant hyperparasitoid species. Aphidius and Aphelinus spp. were attacked by hyperparasitoids at similar rates. In the field, Aphidius spp. were attacked by five species of hyperparasitoid, and Aphelinus spp. were attacked by one, Alloxysta ramulifera. In general, the rate of attack by hyperparasitoids was much lower in field surveys than in our collections from greenhouses

Measurement of ultrashort bi-photon correlation times with an integrated two-colour broadband SU(1,1)-interferometer

The bi-photon correlation time, a measure for the conditional uncertainty in the temporal arrival of two photons from a photon pair source, is a key performance identifier for many quantum spectroscopy applications, with shorter correlation times typically yielding better performance. Furthermore, it provides fundamental insight into the effects of dispersion on the bi-photon state. Here, we retrieve ultrashort bi-photon correlation times of around $100\,\mathrm{fs}$ by measuring simultaneously spectral and temporal interferograms at the output of an SU(1,1) interferometer based on an integrated broadband parametric down-conversion source in a $\mathrm{Ti:LiNbO}_3$ waveguideComment: 8 pages, 5 figure

Diversity, distribution and phenology of Lygus species (Hemiptera: Miridae) in relation to vegetable greenhouses in the lower Fraser Valley, British Columbia, and southwestern Ontario

Lygus spp. were collected from near and inside vegetable greenhouses during three years in the lower Fraser Valley, British Columbia (BC) and in Leamington, Ontario (ON). In BC, the dominant species was Lygus shulli, followed in abundance by L. elisus and L. hesperus; L. lineolaris was not collected in the lower Fraser Valley. In ON, only L. lineolaris was collected. In BC, L. shulli was generally distributed throughout the region, whereas L. hesperus was captured in sweep net samples only in coastal areas. Lygus hesperus appeared to be univoltine in BC. All other species in ON and BC were apparently bivoltine. In ON, numbers of adults collected outside of greenhouses correlated with numbers collected inside greenhouses whereas this was not the case in BC. Differences in flight behaviour, abundance and greenhouse construction may account for this latter difference. Our results highlight the need for different approaches to IPM of pest Lygus species in the ON and BC greenhouse industries

Charting Evolution’s Trajectory: Using Molluscan Eye Diversity to Understand Parallel and Convergent Evolution

For over 100 years, molluscan eyes have been used as an example of convergent evolution and, more recently, as a textbook example of stepwise evolution of a complex lens eye via natural selection. Yet, little is known about the underlying mechanisms that create the eye and generate different morphologies. Assessing molluscan eye diversity and understanding how this diversity came about will be important to developing meaningful interpretations of evolutionary processes. This paper provides an introduction to the myriad of eye types found in molluscs, focusing on some of the more unusual structures. We discuss how molluscan eyes can be applied to the study of evolution by examining patterns of convergent and parallel evolution and provide several examples, including the putative convergence of the camera-type eyes of cephalopods and vertebrates