Comparison of Four Space Propulsion Methods for Reducing Transfer Times of Manned Mars Mission

We assess the possibility of reducing the travel time of a manned mission to Mars by examining four different propulsion methods, and keeping the mass at departure under 2,500 tonnes, for a fixed architecture. We evaluated representative systems of three different state of the art technologies (chemical, nuclear thermal, and electric), and one advance technology, the "Pure Electro-Magnetic Thrust" (PEMT) concept (proposed by Rubbia). A mission architecture mostly based on the Design Reference Architecture 5.0 is assumed in order to estimate the mass budget, that influences the performance of the propulsion system. Pareto curves of the duration of the mission and time of flight versus mass of mission are drawn. We conclude that the ion engine technology, combined with the classical chemical engine, yields the shortest mission times for this architecture with the lowest mass, and that chemical propulsion alone is the best to minimise travel time. The results obtained using the PEMT suggest that it could be a more suitable solution for farther destinations than Mars.Comment: Change in title, abstract and presentation so to clarify the main results. 14 pages, 7 figures and 2 table

Warming up brane-antibrane inflation

We show that, in constructions with additional intersecting D-branes, brane-antibrane inflation may naturally occur in a warm regime, such that strong dissipative effects damp the inflaton's motion, greatly alleviating the associated eta-problem. We illustrate this for D3-antiD3 inflation in flat space with additional flavor D7-branes, where for both a Coulomb-like or a quadratic hybrid potential a sufficient number of e-folds may be obtained for perturbative couplings and O(10-10^4) branes. This is in clear contrast with the corresponding cold scenarios, thus setting the stage for more realistic constructions within fully stabilized compactifications. Such models generically predict a negligible amount of tensor perturbations and non-gaussianity f_NL \sim O(10).Comment: 8 pages, 2 figures; version to be published in Physical Review

Determining the regimes of cold and warm inflation in the susy hybrid model

The SUSY hybrid inflation model is found to dissipate radiation during the inflationary period. Analysis is made of parameter regimes in which these dissipative effects are significant. The scalar spectral index, its running, and the tensor-scalar ratio are computed in the entire parameter range of the model. A clear prediction for strong dissipative warm inflation is found for n_S-1 \simeq 0.98 and a low tensor-scalar ratio much below 10^{-6}. The strong dissipative warm inflation regime also is found to have no \eta-problem and with the field amplitude much below the Planck scale. As will be discussed, this has important theoretical implications in permitting a much wider variety of SUGRA extensions to the basic model.Comment: paragraph added at the end of section V; references added; accepted for publication in Phys. Rev.

Supernova Neutrino Oscillations

Observing a high-statistics neutrino signal from a galactic supernova (SN) would allow one to test the standard delayed explosion scenario and may allow one to distinguish between the normal and inverted neutrino mass ordering due to the effects of flavor oscillations in the SN envelope. One may even observe a signature of SN shock-wave propagation in the detailed time-evolution of the neutrino spectra. A clear identification of flavor oscillation effects in a water Cherenkov detector probably requires a megatonne-class experiment.Comment: Proc. 129 Nobel Symposium "Neutrino Physics", 19-24 Aug 2004, Swede

Crucial Challenges in the Development of Green Extraction Technologies to Obtain Antioxidant Bioactive Compounds from Agro-industrial By–products

Exploitation of agro-industrial by-products represents an important source of bioactive compounds that can be used both directly as ingredients and for the production of functional ingredients. Among these compounds, polyphenols are capable of strengthening endogenous antioxidant defences in human tissues, preventing cardiovascular and neurodegenerative diseases. The present paper aims to evaluate and review various green extraction technologies for a cheap, fast, eco-friendly procedure to obtain these bioactive molecules. Several physicochemical approaches can be used with the aim of optimizing the use of energy, solvents, and pressure; among them are ultrasound-assisted extraction, subcritical and supercritical fluid extraction, extraction with neoteric solvents (ionic liquids, deep eutectic solvents, and natural deep eutectic solvents), microwave-assisted extraction, pressurized liquid extraction, pulsed electric field, multi-frequency multimode modulated technology, rapid solid liquid dynamic extraction, and enzyme-assisted extraction. The challenges and future work regarding the development of these green products for the commercial markets were comprehensively evaluated. This work is licensed under a Creative Commons Attribution 4.0 International License

A geometrical approach to the dynamics of spinor condensates I: Hydrodynamics

In this work, we derive the equations of motion governing the hydrodynamics of spin-F spinor condensates. We pursue a description based on standard physical variables (total density and superfluid velocity), alongside 2F `spin-nodes': unit vectors that describe the spin F state, and also exhibit the point-group symmetry of a spinor condensate's mean-field ground state. The hydrodynamic equations of motion consist of a mass continuity equation, 2F Landau-Lifshitz equations for the spin-nodes, and a modified Euler equation. In particular, we provide a generalization of the Mermin-Ho relation to spin one, and find an analytic solution for the skyrmion texture in the incompressible regime of a spin-half condensate. These results exhibit a beautiful geometrical structure that underlies the dynamics of spinor condensates.Comment: 12 pages. First paper in two-part serie