Remarks on the properties of elliptical galaxies in modified Newtonian dynamics

Two incorrect arguments against MOND in elliptical galaxies could be that the equivalent circular velocity curves tend to become flat at much larger accelerations than in spiral galaxies, and that the Newtonian dark matter halos are more concentrated than in spirals. Here, we compare published scaling relations for the dark halos of elliptical galaxies to the scaling relations expected for MONDian phantom halos. We represent the baryonic content of galaxies by spherical profiles, and their corresponding MONDian phantom halos by logarithmic halos. We then derive the surface densities, central densities, and phase space densities and compare them with published scaling relations. We conclude that it is possible to get flat circular velocity curves at high acceleration in MOND, and that this happens for baryonic distributions described by Jaffe profiles in the region where the circular velocity curve is flat. Moreover, the scaling relations of dark halos of ellipticals are remarkably similar to the scaling relations of phantom halos of MOND.Comment: Accepted for publication in A and

The distribution of interstellar dust in CALIFA edge-on galaxies via oligochromatic radiative transfer fitting

We investigate the amount and spatial distribution of interstellar dust in edge-on spiral galaxies, using detailed radiative transfer modeling of a homogeneous sample of 12 galaxies selected from the CALIFA survey. Our automated fitting routine, FitSKIRT, was first validated against artificial data. This is done by simultaneously reproducing the SDSS $g$-, $r$-, $i$- and $z$-band observations of a toy model in order to combine the information present in the different bands. We show that this combined, oligochromatic fitting, has clear advantages over standard monochromatic fitting especially regarding constraints on the dust properties. We model all galaxies in our sample using a three-component model, consisting of a double exponential disc to describe the stellar and dust discs and using a S\'ersic profile to describe the central bulge. The full model contains 19 free parameters, and we are able to constrain all these parameters to a satisfactory level of accuracy without human intervention or strong boundary conditions. Apart from two galaxies, the entire sample can be accurately reproduced by our model. We find that the dust disc is about 75% more extended but only half as high as the stellar disc. The average face-on optical depth in the V-band is $0.76$ and the spread of $0.60$ within our sample is quite substantial, which indicates that some spiral galaxies are relatively opaque even when seen face-on.Comment: 18 pages, 6 figures, 4 tables, Accepted for publication in MNRA

An extremely low gas-to-dust ratio in the dust-lane lenticular galaxy NGC 5485

Date of Acceptance: 21/07/2014Peer reviewe

Preliminary spacecraft design by means of structured-chromosome genetic algorithms

This paper presents a new methodology for complex system design by means of optimisation techniques. Within the Model-based Engineering approach, optimisation algorithms are used to explore optimal solutions of highly coupled and nonlinear systems. In such scenario, the optimal technology has to be identified and its settings have to be optimised. Relying on optimisation strategies for both the challenges brings to complex mixed-variable problem formulations involving continuous, integer and categorical parameters. Furthermore, part of the parameters are required only if certain technologies are adopted, bringing to variable-size formulations that standard optimisers cannot manage. Therefore, the proposed methodology relies on the use of variable-size mixed-variable global optimiser Structured-Chromosome Genetic Algorithm (SCGA). The advantages of this new method are shown by applying it for solving a space system preliminary design. In particular, two variants have been implemented distinguished by two different levels of complexity. To better appreciate the proposed approach, the same problems have been reformulated to be treated by a well known and appreciated optimiser in the field of spacecraft design, Multi– Population Adaptive Inflationary Differential Evolution Algorithm (MP–AIDEA). The final results of the two approaches are compared and commented

Navel Healing and Calf Fitness for Transport

open5noDairy male calves are at risk of welfare compromise as they are usually transported at a very young age. The European Union has set a “completely healed navel” requirement for calf transport; moreover, a minimum age is established for longer journeys. However, this requirement has proven to be prone to misinterpretation. This study aimed to clarify what is meant by “navel healing” and to provide strong elements for reaching a consensus. The navels of 299 dairy calves (55 males, 244 females) aged 0–90 days were examined and scored 1 to 5 according to their healing status. Based on our results, a completely dry and shriveled navel (score 3) would imply a 25.5–38.0% risk of transporting too young calves. Alternatively, the presence of a scab covering the umbilical wound (score 4) would entail a 4.3% risk of transporting calves less than 10 days old and could be considered good practice for transporting calves (except for journeys exceeding 8 h). Conversely, complete navel healing (score 5) guarantees that calves that are too young are not transported; therefore, it should be considered best practice for transporting calves in general and the minimum requirement for transporting calves for journeys exceeding 8 h.openRoccaro, Mariana; Bolcato, Marilena; Masebo, Naod Thomas; Gentile, Arcangelo; Peli, AngeloRoccaro, Mariana; Bolcato, Marilena; Masebo, Naod Thomas; Gentile, Arcangelo; Peli, Angel

High-lift devices topology optimisation using structured-chromosome genetic algorithm

This paper addresses the problem of including the choice of the High-Lift Devices (HLDs) configuration as a decision variable of an automatic optimisation tool. This task requires the coupling of an estimation routine and an optimisation algorithm. For the former, SU2 flow solver has been used. The Structured-Chromosome Genetic Algorithm (SCGA) optimiser has been employed to search for the optimal HLD. SCGA can overcome the limitations dictated by standard fixed-size continuous optimisation algorithms. Indeed, using hierarchical formulations, it can manage configurational decisions that are conventionally the responsibility of expert designers. The search algorithm bases its strategy on revised genetic operators conceived for handling hierarchical search spaces. The presented research not only shows the practicability of delegating to a specialised optimisation algorithm the complete HLD design but is intended to be a proof of concept for the whole field of multidisciplinary design optimisation. Indeed, the aerospace sector as a whole would benefit by reducing human intervention from the decision process