Wormhole cosmic strings

We construct regular multi-wormhole solutions to a gravitating $\sigma$ model in three space-time dimensions, and extend these solutions to cylindrical traversable wormholes in four and five dimensions. We then discuss the possibility of identifying wormhole mouths in pairs to give rise to Wheeler wormholes. Such an identification is consistent with the original field equations only in the absence of the $\sigma$-model source, but with possible naked cosmic string sources. The resulting Wheeler wormhole space-times are flat outside the sources and may be asymptotically Minkowskian.Comment: 17 pages, LaTeX, 4 figures (hard copy available on request

Phantom Black Holes and Sigma Models

We construct static multicenter solutions of phantom Einstein-Maxwell-dilaton theory from null geodesics of the target space, leading to regular black holes without spatial symmetry for certain discrete values of the dilaton coupling constant. We also discuss the three-dimensional gravitating sigma models obtained by reduction of phantom Einstein-Maxwell, phantom Kaluza-Klein and phantom Einstein-Maxwell-dilaton-axion theories. In each case, we generate by group transformations phantom charged black hole solutions from a neutral seed.Comment: 19 page

Ring Wormholes in D-Dimensional Einstein and Dilaton Gravity

On the basis of exact solutions to the Einstein-Abelian gauge-dilaton equations in $D$-dimensional gravity, the properties of static axial configurations are discussed. Solutions free of curvature singularities are selected; they can be attributed to traversible wormholes with cosmic string-like singularities at their necks. In the presence of an electromagnetic field some of these wormholes are globally regular, the string-like singularity being replaced by a set of twofold branching points. Consequences of wormhole regularity and symmetry conditions are discussed. In particular, it is shown that (i) regular, symmetric wormholes have necessarily positive masses as viewed from both asymptotics and (ii) their characteristic length scale in the big charge limit ($GM^2 \ll Q^2$) is of the order of the ``classical radius" $Q^2/M$.Comment: Latex file, 15 page

Creep motion of a model frictional system

We report on the dynamics of a model frictional system submitted to minute external perturbations. The system consists of a chain of sliders connected through elastic springs that rest on an incline. By introducing cyclic expansions and contractions of the springs we observe a reptation of the chain. We account for the average reptation velocity theoretically. The velocity of small systems exhibits a series of plateaus as a function of the incline angle. Due to elastic e ects, there exists a critical amplitude below which the reptation is expected to cease. However, rather than a full stop of the creep, we observe in numerical simulations a transition between a continuous-creep and an irregular-creep regime when the critical amplitude is approached. The latter transition is reminiscent of the transition between the continuous and the irregular compaction of granular matter submitted to periodic temperature changes

Kaluza-Klein and Gauss-Bonnet cosmic strings

We make a systematic investigation of stationary cylindrically symmetric solutions to the five-dimensional Einstein and Einstein-Gauss-Bonnet equations. Apart from the five-dimensional neutral cosmic string metric, we find two new exact solutions which qualify as cosmic strings, one corresponding to an electrically charged cosmic string, the other to an extended superconducting cosmic string surrounding a charged core. In both cases, test particles are deflected away from the singular line source. We extend both kinds of solutions to exact multi-cosmic string solutions.Comment: 26 pages, LaTex, no figure

Black hole mass and angular momentum in topologically massive gravity

We extend the Abbott-Deser-Tekin approach to the computation of the Killing charge for a solution of topologically massive gravity (TMG) linearized around an arbitrary background. This is then applied to evaluate the mass and angular momentum of black hole solutions of TMG with non-constant curvature asymptotics. The resulting values, together with the appropriate black hole entropy, fit nicely into the first law of black hole thermodynamics.Comment: 20 pages, references added, version to appear in Classical and Quantum Gravit

The olfactory basis of orchid pollination by mosquitoes.

Mosquitoes are important vectors of disease and require sources of carbohydrates for reproduction and survival. Unlike host-related behaviors of mosquitoes, comparatively less is understood about the mechanisms involved in nectar-feeding decisions, or how this sensory information is processed in the mosquito brain. Here we show that Aedes spp. mosquitoes, including Aedes aegypti, are effective pollinators of the Platanthera obtusata orchid, and demonstrate this mutualism is mediated by the orchid's scent and the balance of excitation and inhibition in the mosquito's antennal lobe (AL). The P. obtusata orchid emits an attractive, nonanal-rich scent, whereas related Platanthera species-not visited by mosquitoes-emit scents dominated by lilac aldehyde. Calcium imaging experiments in the mosquito AL revealed that nonanal and lilac aldehyde each respectively activate the LC2 and AM2 glomerulus, and remarkably, the AM2 glomerulus is also sensitive to N,N-diethyl-meta-toluamide (DEET), a mosquito repellent. Lateral inhibition between these 2 glomeruli reflects the level of attraction to the orchid scents. Whereas the enriched nonanal scent of P. obtusata activates the LC2 and suppresses AM2, the high level of lilac aldehyde in the other orchid scents inverts this pattern of glomerular activity, and behavioral attraction is lost. These results demonstrate the ecological importance of mosquitoes beyond operating as disease vectors and open the door toward understanding the neural basis of mosquito nectar-seeking behaviors

Production of freshwater benthic macroinvertebrates from pig dung: fertilization effect and optimal dose research

Different pig dung doses were used to fertilize medium production of freshwater benthic macroinvertebrates in order to test the fertilization effect and determine the optimal dose. In fact, the experiment was carried out in triplicate, for 42 days in plastic buckets. These buckets were grouped in seven treatments (T1, T2, T3, T4, T5, T6, and T7) which were fertilized (respective doses of 5%, 10%, 15%, 25%, 50%, 75% and 100% with pig dung in relation to the total substrate volume) and a control (T0) which was not fertilized (0% of pig dung). Each bucket was seeded in benthic macroinvertebrates with an initial density of 9 individual/dm3 (D0). The results revealed that the utilization of pig dung improved the water chemical properties in the production medium as well as the macroinvertebrates density (p < 0.05). The optimal production of the latter was obtained with the dose of pig dung applied to treatment T5 (50%), that is 150 g of dry dejections per dm3 of substrate (150 g/dm3) with a total average density of 742 ± 569 individual/dm3. The treatment T5 (50%) constitutes then the dry pig dung optimal dose to be recommended for benthic macroinvertebrates production.© 2016 International Formulae Group. All rights reserved.Keywords: Fertilization, macroinvertebrates, optimal dose, pig dung, productio

LAS: a software platform to support oncological data management

The rapid technological evolution in the biomedical and molecular oncology fields is providing research laboratories with huge amounts of complex and heterogeneous data. Automated systems are needed to manage and analyze this knowledge, allowing the discovery of new information related to tumors and the improvement of medical treatments. This paper presents the Laboratory Assistant Suite (LAS), a software platform with a modular architecture designed to assist researchers throughout diverse laboratory activities. The LAS supports the management and the integration of heterogeneous biomedical data, and provides graphical tools to build complex analyses on integrated data. Furthermore, the LAS interfaces are designed to ease data collection and management even in hostile environments (e.g., in sterile conditions), so as to improve data qualit

Self-Dual Chern-Simons Solitons in (2+1)-Dimensional Einstein Gravity

We consider here a generalization of the Abelian Higgs model in curved space, by adding a Chern--Simons term. The static equations are self-dual provided we choose a suitable potential. The solutions give a self-dual Maxwell--Chern--Simons soliton that possesses a mass and a spin