The age-metallicity relationship in the Fornax spheroidal dwarf galaxy

We produce a comprehensive field star age-metallicity relationship (AMR) from the earliest epoch until ~ 1 Gyr ago for three fields in the Fornax dSph galaxy by using VI photometric data obtained with FORS1 at the VLT. We find that the innermost one does not contains dominant very old stars (age > 12 Gyr), whereas the relatively outer field does not account for representative star field populations younger than ~ 3 Gyr. When focusing on the most prominent stellar populations, we find that the derived AMRs are engraved by the evidence of a outside-in star formation process. The studied fields show bimodal metallicity distributions peaked at [Fe/H] = (-0.95 +- 0.15) dex and (-1.15 or -1.25 +- 0.05) dex, respectively, but only during the first half of the entire galaxy lifetime. Furthermore, the more metal-rich population appears to be more numerous in the outer fields, while in the innermost Fornax field the contribution of both metallicity populations seems to be similar. We also find that the metallicity spread ~ 6 Gyr ago is remarkable large, while the intrinsic metallicity dispersion at ~ 1-2 Gyr results smaller than that for the relatively older generations of stars. We interpret these outcomes as a result of a possible merger of two galaxies that would have triggered a star formation bursting process that peaked between ~ 6 and 9 Gyr ago, depending on the position of the field in the galaxy.Comment: 7 pages, 5 figures, MNRAS, in pres

Host and environmental factors as determinants of equine piroplasmosis seroprevalence in Central Spain

Aim of study: To estimate equine piroplasmosis seroprevalence, identify associated risk factors and assess infection recentness.Area of study: Community of Madrid (Central Spain)Material and methods: Sera from 139 horses and 40 donkeys were examined by cELISA to evaluate Babesia caballi and Theileria equi seroprevalences and examine potential risk factors. They included species, gender, age, breed, colour coat, dedication, external parasite treatments, access to pasture, contact with other species, new introduction, tick infestation, farm altitude, land cover, soil type and climatic zone. A bivariate analysis was performed and significant variables were included in a logistic regression model to examine their independent contribution. In positive samples ELISA inhibition percentiles (EIPs) were used to assess whether infections were old or recent.Main results: True seroprevalence (95% CI), adjusted for test sensitivity and specificity was 19% (13-27) for T. equi and 1% (0-3) for B. caballi. In the bivariate analysis, T. equi seroprevalence varied significantly according to horse and farm-level explanatory variables; high seroprevalence groups generally had high EIPs suggesting recent infection. The multivariable analysis revealed that T. equi seroprevalence increased with age, it was higher in police horses compared to sporting, recreational and breeding animals and in those living in lower altitude where planosol soil type was predominant.Research highlights: T. equi seroprevalence in the area was significantly higher than B. caballi seroprevalence and depends on animal management and environmental factors that affect vector abundance and diversity. Identified risk factors must be considered to improve tick and tick-borne disease control and prevention

Adventures of a tidally induced bar

Using N-body simulations, we study the properties of a bar induced in a discy dwarf galaxy as a result of tidal interaction with the Milky Way. The bar forms at the first pericentre passage and survives until the end of the evolution at 10 Gyr. Fourier decomposition of the bar reveals that only even modes are significant and preserve a hierarchy so that the bar mode is always the strongest. They show a characteristic profile with a maximum, similar to simulated bars forming in isolated galaxies and observed bars in real galaxies. We adopt the maximum of the bar mode as a measure of the bar strength and we estimate the bar length by comparing the density profiles along the bar and perpendicular to it. The bar strength and the bar length decrease with time, mainly at pericentres, as a result of tidal torques acting at those times and not to secular evolution. The pattern speed of the bar varies significantly on a time-scale of 1 Gyr and is controlled by the orientation of the tidal torque from the Milky Way. The bar is never tidally locked, but we discover a hint of a 5/2 orbital resonance between the third and fourth pericentre passage. The speed of the bar decreases in the long run so that the bar changes from initially rather fast to slow in the later stages. The boxy/peanut shape is present for some time and its occurrence is preceded by a short period of buckling instability

Subjective caregiver burden and anxiety in informal caregivers: a systematic review and meta-analysis

There is increasing evidence that subjective caregiver burden is an important determinant of clinically significant anxiety in family carers. This meta-analysis aims to synthesise this evidence and investigate the relationship between subjective caregiver burden and anxiety symptoms in informal caregivers. We searched PubMed, CINAHL and PsycINFO up to January 2020. Combined estimates were obtained using a random-effects model. After screening of 4,312 articles, 74 studies (with 75 independent samples) were included. There was a large, positive association between subjective caregiver burden and anxiety symptoms (r = 0.51; 95% CI = 0.47, 0.54; I2 = 0.0%). No differences were found in subgroup analyses by type of study design (cross-sectional vs. longitudinal), sampling, control of confounders or care-recipient characteristics. Subjective caregiver burden is an important risk factor for anxiety in informal caregivers. Targeting subjective caregiver burden could be beneficial in preventing clinically significant anxiety for the increasing number of family carers worldwide

Galaxy cluster mergers as triggers for the formation of jellyfish galaxies: case study of the A901/2 system

The A901/2 system is a rare case of galaxy cluster interaction, in which two galaxy clusters and two smaller groups are seen in route of collision with each other simultaneously. Within each of the four substructures, several galaxies with features indicative of jellyfish morphologies have been observed. In this paper, we propose a hydrodynamic model for the merger as a whole, compatible with its diffuse X-ray emission, and correlate the gas properties in this model with the locations of the jellyfish galaxy candidates in the real system. We find that jellyfish galaxies seem to be preferentially located near a boundary inside each subcluster where diffuse gas moving along with the subcluster and diffuse gas from the remainder of the system meet. The velocity change in those boundaries is such that a factor of up to $\sim$1000 increase in the ram pressure takes place within a few hundred kpc, which could trigger the high rate of gas loss necessary for a jellyfish morphology to emerge. A theoretical treatment of ram pressure stripping in the environment of galaxy cluster mergers has not been presented in the literature so far; we propose that this could be a common scenario for the formation of jellyfish morphologies in such systems.Comment: Accepted for publication in MNRAS. 10 pages, 9 figure

Exploring the effects of spanwise wing deformation on lift coefficient and trailing vortices properties at low Reynolds number.

We have conducted an experimental investigation on the effect of spanwise wing deformation on the lift coefficient and the properties of the wingtip vortices generated by several NACA0012 symmetric wing models.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Characterization fo the molecular mechanism of action of a new inhibitor of the complex cyclin-dependent kinase 2-cyclin A

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