The Primary Pretenders

We call a composite number q such that there exists a positive integer b with b^p == b (mod q) a prime pretender to base b. The least prime pretender to base b is the primary pretender q_b. It is shown that there are only 132 distinct primary pretenders, and that q_b is a periodic function of b whose period is the 122-digit number 19568584333460072587245340037736278982017213829337604336734362- 294738647777395483196097971852999259921329236506842360439300.Comment: 7 page

Subscale, hydrogen-burning, airframe-integrated-scramjet: Experimental and theoretical evaluation of a water cooled strut airframe-integrated-scramjet: Experimental leading edge

A water-cooled leading-edge design for an engine/airframe integrated scramjet model strut leading edge was evaluated. The cooling design employs a copper cooling tube brazed just downstream of the leading edge of a wedge-shaped strut which is constructed of oxygen-free copper. The survival of the strut leading edge during a series of tests at stagnation point heating rates confirms the practicality of the cooling design. A finite difference thermal model of the strut was also proven valid by the reasonable agreement of calculated and measured values of surface temperature and cooling-water heat transfer

A synthetic sample of short-cadence solar-like oscillators for TESS

NASA's Transiting Exoplanet Survey Satellite (TESS) has begun a two-year survey of most of the sky, which will include lightcurves for thousands of solar-like oscillators sampled at a cadence of two minutes. To prepare for this steady stream of data, we present a mock catalogue of lightcurves, designed to realistically mimic the properties of the TESS sample. In the process, we also present the first public release of the asteroFLAG Artificial Dataset Generator, which simulates lightcurves of solar-like oscillators based on input mode properties. The targets are drawn from a simulation of the Milky Way's populations and are selected in the same way as TESS's true Asteroseismic Target List. The lightcurves are produced by combining stellar models, pulsation calculations and semi-empirical models of solar-like oscillators. We describe the details of the catalogue and provide several examples. We provide pristine lightcurves to which noise can be added easily. This mock catalogue will be valuable in testing asteroseismology pipelines for TESS and our methods can be applied in preparation and planning for other observatories and observing campaigns.Comment: 14 pages, 6 figures, accepted for publication in ApJS. Archives containing the mock catalogue are available at https://doi.org/10.5281/zenodo.1470155 and the pipeline to produce it at https://github.com/warrickball/s4tess . The first public release of the asteroFLAG Artificial Dataset Generator v3 (AADG3) is described at https://warrickball.github.io/AADG3

Discovery of circularly polarised radio emission from SS 433

We report the discovery of circularly polarised radio emission from the radio-jet X-ray binary SS 433 with the Australia Telescope Compact Array. The flux density spectrum of the circular polarization, clearly detected at four frequencies between 1 - 9 GHz, has a spectral index of (-0.9 +/- 0.1). Multiple components in the source and a lack of very high spatial resolution do not allow a unique determination of the origin of the circular polarization, nor of the spectrum of fractional polarization. However, we argue that the emission is likely to arise in the inner regions of the binary, possibly via propagation-induced conversion of linear to circular polarization, and the fractional circular polarization of these regions may be as high as 10%. Observations such as these have the potential to investigate the composition, whether pairs or baryonic, of the ejecta from X-ray binaries.Comment: Accepted for publication in ApJ Letter

Attractive instability of oppositely charged membranes induced by charge density fluctuations

We predict the conditions under which two oppositely charged membranes show a dynamic, attractive instability. Two layers with unequal charges of opposite sign can repel or be stable when in close proximity. However, dynamic charge density fluctuations can induce an attractive instability and thus facilitate fusion. We predict the dominant instability modes and timescales and show how these are controlled by the relative charge and membrane viscosities. These dynamic instabilities may be the precursors of membrane fusion in systems where artificial vesicles are engulfed by biological cells of opposite charge

Notas sobre los artropodos que viven en el pijuayo (Bactris gasipaes H.B.K. : Palmae) en la Amazonia peruana

The peachpalm, #Bactris gasipaes$ H.B.K. is cultivated in the Amazon basin and in Central America for its fruits and for the production of heart palm. Several insects and mites attack it. Some observations in Peruvian Amazonia on those pests and other associated insects are reported. Some species are new for Peru. (Résumé d'auteur

Number theoretic example of scale-free topology inducing self-organized criticality

In this work we present a general mechanism by which simple dynamics running on networks become self-organized critical for scale free topologies. We illustrate this mechanism with a simple arithmetic model of division between integers, the division model. This is the simplest self-organized critical model advanced so far, and in this sense it may help to elucidate the mechanism of self-organization to criticality. Its simplicity allows analytical tractability, characterizing several scaling relations. Furthermore, its mathematical nature brings about interesting connections between statistical physics and number theoretical concepts. We show how this model can be understood as a self-organized stochastic process embedded on a network, where the onset of criticality is induced by the topology.Comment: 4 pages, 3 figures. Physical Review Letters, in pres

Observations préliminaires sur les insectes nuisibles à l'araza (Eugenia stipitata McVaugh, Myrtaceae), nouvelle culture fruitière en Amazonie

L'araza (#Eugenia stipitata McVaugh, #Myrtaceae) est un arbuste fruitier amazonien récemment domestiqué, qui présente un fort potentiel agro-industriel. Afin d'inventorier les insectes nuisibles, des évaluations ont été entreprises entre 1988 et 1992 dans les plantations de trois centres de recherche et dans deux plantations privées, proches d'Iquitos, en Amazonie péruvienne. Neuf espèces nuisibles ont été identifiées dont cinq affectent les fruits, trois sont des défoliateurs et la dernière coupe les rameaux. Quatre de ces espèces sont considérées comme nuisibles : #Anastrepha obliqua, #Conotrachelus eugeniae et #Atractomerus immigrans, qui influent sur la qualité et le volume des fruits récoltés ainsi que #Plectrophoroides impressicollis qui peut détruire totalement les inflorescences. (Résume d'auteur

User-centred improvements to energy efficiency products and renewable energy systems: research on household adoption and use

The development and rapid consumer adoption of energy efficiency products and renewable energy systems are key elements of the UK and the EU carbon reduction strategies to meet the challenge of climate change. Many such technologies are available for domestic use, but despite government incentives to meet carbon reduction targets consumer adoption has been slow. This Open University research with 111 in-depth interviews plus an on-line survey with nearly 400 responses, investigates consumer adoption, non-adoption and use of these technologies. Results show that it is important to research consumer use experiences, problems and requirements when designing and developing “green” technologies. With results tailored to each technology, this study shows that user-centred improvements are required to improve functionality, ergonomics, inter-connectedness with other systems and symbolic value, and to reduce cost and payback. User-centred research supports new product/system design and development to promote more rapid adoption and carbon-saving use of energy efficient and renewable technologies in homes