Rotating black holes in the FI-gauged N=2N=2, D=4D=4 CP‾n\overline{\mathbb{C}\text{P}}^n model

We construct supersymmetric black holes with rotation or NUT charge for the $\overline{\mathbb{C}\text{P}}^n$- and the $\text{t}^3$ model of $N=2$, $D=4$ $\text{U}(1)$ FI-gauged supergravity. The solutions preserve 2 real supercharges, which are doubled for their near-horizon geometry. For the $\overline{\mathbb{C}\text{P}}^n$ model we also present a generalization to the nonextremal case, which turns out to be characterized by a Carter-Pleba\'nski-type metric, and has $n+3$ independent parameters, corresponding to mass, angular momentum as well as $n+1$ magnetic charges. We discuss the thermodynamics of these solutions, obtain a Christodoulou-Ruffini mass formula, and shew that they obey a first law of thermodynamics and that the product of horizon areas depends on the angular momentum and the magnetic charges only. At least some of the BPS black holes that we obtain may become instrumental for future microscopic entropy computations involving a supersymmetric index.Comment: 34 pages, uses jheppub.sty. Final version to appear in JHE

Dyonic black holes at arbitrary locations

Abstract We construct and study stationary, asymptotically flat multicenter solutions describing regular black holes with non-Abelian hair (colored magnetic-monopole and dyon fields) in two models of N = 2 $$\mathcal{N}=2$$ , d = 4 Super-Einstein-Yang-Mills theories: the quadratic model ℂ ℙ ¯ 3 $${\overline{\mathrm{\mathbb{C}}\mathrm{\mathbb{P}}}}^3$$ and the cubic model ST[2, 6], which can be embedded in 10-dimensional Heterotic Supergravity. These solutions are based on the multicenter dyon recently discovered by one of us, which solves the SU(2) Bogomol’nyi and dyon equations on E 3 $${\mathbb{E}}^3$$ . In contrast to the well-known Abelian multicenter solutions, the relative positions of the non-Abelian black-hole centers are unconstrained. We study necessary conditions on the parameters of the solutions that ensure the regularity of the metric. In the case of the ℂ ℙ ¯ 3 $${\overline{\mathrm{\mathbb{C}}\mathrm{\mathbb{P}}}}^3$$ model we show that it is enough to require the positivity of the “masses” of the individual black holes, the finiteness of each of their entropies and their superadditivity. In the case of the ST[2, 6] model we have not been able to show that analogous conditions are sufficient, but we give an explicit example of a regular solution describing thousands of non-Abelian dyonic black holes in equilibrium at arbitrary relative positions. We also construct non-Abelian solutions that interpolate smoothly between just two aDS2×S2 vacua with different radii (dumbbell solutions)

On a family of α′-corrected solutions of the Heterotic Superstring effective action

We compute explicitly the first-order in α′ corrections to a family of solutions of the Heterotic Superstring effective action that describes fundamental strings with momentum along themselves, parallel to solitonic 5-branes with Kaluza-Klein monopoles (Gibbons-Hawking metrics) in their transverse space. These solutions correspond to 4-charge extremal black holes in 4 dimensions upon dimensional reduction on T6. We show that some of the α′ corrections can be cancelled by introducing solitonic SU(2) × SU(2) Yang-Mills fields, and that this family of α′-corrected solutions is invariant under α′-corrected T-duality transformations. We study in detail the mechanism that allows us to compute explicitly these α′ corrections for the ansatz considered here, based on a generalization of the ’t Hooft ansatz to hyperKähler spacesThis work has been supported in part by the MINECO/FEDER, UE grants FPA2015-66793-P and FPA2015-63667-P, by the Italian INFN and by the Spanish Research Agency (Agencia Estatal de Investigación) through the grant IFT Centro de Excelencia Severo Ochoa SEV-2016-0597. AR is supported by “Centro de Excelencia Internacional UAM/CSI

α′ corrections of Reissner-Nordström black holes

We study the first-order in α′ corrections to non-extremal 4-dimensional dyonic Reissner-Nordström (RN) black holes with equal electric and magnetic charges in the context of Heterotic Superstring effective field theory (HST) compactified on a T6. The particular embedding of the dyonic RN black hole in HST considered here is not supersymmetric in the extremal limit. We show that, at first order in α′, consistency with the equations of motion of the HST demands additional scalar and vector fields become active, and we provide explicit expressions for all of them. We determine analytically the position of the event horizon of the black hole, as well as the corrections to the extremality bound, to the temperature and to the entropy, checking that they are related by the first law of black-hole thermodynamics, so that ∂S/∂M = 1/T. We discuss the implications of our results in the context of the Weak Gravity Conjecture, clarifying that entropy corrections for fixed mass and charge at extremality do not necessarily imply corrections to the extremal charge-to-mass ratioThis work has been supported in part by the MCIU, AEI, FEDER (UE) grant PGC2018- 095205-B-I00, CONACyT grant 237351 and by the Spanish Research Agency (Agencia Estatal de Investigación) through the grant IFT Centro de Excelencia Severo Ochoa SEV- 2016-0597. PAC was mostly funded by Fundación La Caixa through a La Caixa - Severo Ochoa" International pre-doctoral grant. In the last stages of this project PAC was supported by the KU Leuven grant \Bijzonder Onderzoeksfonds C16/16/00

Red-Emitting Tetracoordinate Organoboron Chelates: Synthesis, Photophysical Properties, and Fluorescence Microscopy

Seven tetracoordinate organoboron fluorophores with heterobiaryl N,O- or N,N-chelate ligands were prepared and photophysically characterized (in toluene). The electronic variation of the heteroaromatic moiety provided a means for the fine-tuning of the UV/vis absorption and emission spectra. In the most interesting cases, the spectra were red-shifted to maximum absorbance at wavelengths longer than 500 nm and emission maxima between 620 and 660 nm. The pronounced intramolecular charge-transfer character of the dyes yielded large Stokes shifts (3500-5100 cm), while maintaining appreciable fluorescence quantum yields of up to 0.2 for emission maxima longer than 600 nm. The lipophilic character of the dyes enabled their application as stains of vesicle substructures in confocal fluorescence microscopy imaging.Ministerio de Economía y Competitividad CTQ2014-54729 - C2 - 1 - P for U.P., CTQ2013 - 48164 - C2 - 1 - P , CTQ2013 - 48164 - C2 - 2 - P for A.R., CTQ2013 - 41339 - P, CTQ2015 - 71896 - REDT for E.P.I., Ramón y Cajal contract RYC - 2013 - 12585 for A.R.FEDER FundJunta de Andalucía 2012/FQM - 2140 for U.P., 2009/FQM - 4537 and 2012/FQM - 1078 for A.R

Power Converter Topologies for a High Performance Transformer Rectifier Unit in Aircraft Applications

This paper presents some power converter architectures and circuit topologies, which can be used to achieve the requirements of the high performance transformer rectifier unit in aircraft applications, mainly as: high power factor with low THD, high efficiency and high power density. The voltage and the power levels demanded for this application are: three-phase line-to-neutral input voltage of 115 or 230V AC rms (360 – 800Hz), output voltage of 28V DC or 270V DC(new grid value) and the output power up to tens of kilowatts

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Crossing the phantom divide in an interacting generalized Chaplygin gas

Unified generalized Chaplygin gas models assuming an interaction between dark energy and dark matter fluids have been previously proposed. Following these ideas, we consider a particular relation between dark densities, which allows the possibility of a time varying equation of state for dark energy that crosses the phantom divide at a recent epoch. Moreover, these densities decay during all the evolution of the Universe, avoiding a Big Rip. We find also a scaling solution, i.e. these densities are asymptotically proportional in the future, which contributes to the solution of the coincidence problem.Comment: Improved version, 10 pages, 4 figures, References adde

Microalgae Cultivation for Secondary Metabolite Production

Microalgae including cyanobacteria have been recognized as an excellent source of fine chemicals, renewable fuels, vitamins, and proteins and usually are found in health food stores around the world. However, the accumulation of these compounds generally occurs at end of the exponential growth phase; furthermore, biomass density in cultivation commonly is low. Open cultures have been used for pigment, biofuels, and biomass production, but these types of culture system are not a good choice for the production of fine chemicals, due to contamination problems and the expensive production costs. Closed photobioreactors can be operated in a continuous cultivation providing an increase on biomass density and contamination-free condition and generally working at a maximum growth rate under specific conditions; besides, these systems can recycle the consumed culture medium at least three times before a new enriched medium is supplied, generating a more cost-effective production system. In addition, microalgae metabolism can be manipulated to provoke a specific secondary metabolite accumulation by the addition of organic carbon source or changing light intensity or both. In other words, photobioreactors can operate in continuous mode, with efficient light supply and the supplementation of organic carbon source to produce fine biochemicals such as anticancer, antibacterial, antioxidant, lectins, antiviral compounds, and biofuels

Power distribution in a 13 kW three-phase rectifier system: impact on weight, volume and efficiency

This paper addresses the power delivery strategy on an aircraft application consisting on seven isolated DC loads to be supplied from the AC grid. Distributed or centralized power processing is evaluated taking into account weight and efficiency. Additionally, the rectifier switching frequency has to be synchronized with an external frequency clock to minimize the interference of the converter harmonics with the loads