2,150 research outputs found
Merging of Elliptical Galaxies as Possible Origin of the Intergalactic Stellar Population
We present N-body simulations of elliptical galaxy encounters into dry
mergers to study the resulting unbound intergalactic stellar population, in
particular that of the post-Main Sequence stars. The systems studied are pairs
of spherical galaxies without dark halos. The stellar content of the model
galaxies is distributed into mass-bins representing low- and intermediate-mass
stars (0.85 -- 8 solar masses) according to Salpeter's initial mass function.
Our models follow the dynamical evolution of galaxy encounters colliding
head-on from initial low-energy parabolic or high-energy mildly-hyperbolic
orbits, and for a choice of initial-mass ratios. The merging models with
initial parabolic orbits have M2/M1 =1 and 10, and they leave behind
respectively 5.5 % and 10 % of the total initial mass as unbound stellar mass.
The merging model with initial hyperbolic orbit has M2/M1 =1, and leaves behind
21 % of its initial stellar mass as unbound mass, showing that the efficiency
in producing intergalactic stars through a high-energy hyperbolic encounter is
about four times than through a parabolic encounter of the same initial mass
ratio. By assuming that all progenitor galaxies as well as the merger remnants
are homologous systems we obtained that the intergalactic starlight is 17 % and
28 % of the total starlight respectively for the parabolic and hyperbolic
encounters with M2/M1 =1. In all models, different mass stars have the same
probability of becoming unbound and feeding the intergalactic stellar
population.Comment: The Astrophysical Journal, in pres
Evolution along the sequence of S0 Hubble types induced by dry minor mergers. II - Bulge-disk coupling in the photometric relations through merger-induced internal secular evolution
Galaxy mergers are considered as questionable mechanisms for the evolution of
lenticular galaxies (S0's), on the basis that even minor ones induce structural
changes that are difficult to reconcile with the strong bulge-disk coupling
observed in the photometric scaling relations of S0's. We check if the
evolution induced onto S0's by dry intermediate and minor mergers can reproduce
their photometric scaling relations, analysing the bulge-disk decompositions of
the merger simulations presented in Eliche-Moral et al. (2012). The mergers
induce an evolution in the photometric planes compatible with the data of S0's,
even in those ones indicating a strong bulge-disk coupling. The mergers drive
the formation of the observed photometric relation in some cases, whereas they
induce a slight dispersion compatible with data in others. Therefore, this
evolutionary mechanism tends to preserve these scaling relations. In those
photometric planes where the morphological types segregate, the mergers always
induce evolution towards the region populated by S0's. The structural coupling
of the bulge and the disk is preserved or reinforced because the mergers
trigger internal secular processes in the primary disk that induce significant
bulge growth, even although these models do not induce bars. Intermediate and
minor mergers can thus be considered as plausible mechanisms for the evolution
of S0's attending to their photometric scaling relations, as they can preserve
and even strengthen any pre-existing structural bulge-disk coupling, triggering
significant internal secular evolution (even in the absence of bars or
dissipational effects). This means that it may be difficult to isolate the
effects of pure internal secular evolution from those of the merger-driven one
in present-day early-type disks (abridged).Comment: Accepted for publication in Astronomy & Astrophysics, 13 pages, 8
figures. Definitive version after proofs. Added references and corrected
typo
Improving Cr (VI) Extraction through Electrodialysis
A laboratory study has been carried out to determine the feasibility of in situ remediation of chromium (VI)
contaminated soil using electrodialysis. In a classic setup, this technique implies the application of a low intensity direct
current to the soil, which is separated from the electrode compartments by ion-exchange membranes. If the pollutants
are ionic compounds, they can be forced to migrate to the oppositely charged electrode by electro-migration.
Membranes selectively impede the flow of ions in the electrode compartments back to the soil. If a metal species is
naturally present as an anion, mobilization from the soil at alkaline pH can be realized and, at the same time, the
mobilization of other metal cations that occur at low pH can be minimized.
Experiments have been carried out with clayey soils (kaolinite clay and soil clay mixtures) that have been
characterized and then contaminated by mixing with a potassium dichromate solution for several days. Initial Cr (VI)
content ranges from 500 to 4000 mg/kg. Treatment tests were carried out in an acrylic laboratory cells consisting of a
central soil compartment and two electrode compartments located at both ends of the column. Dimensionally stable
titanium electrodes coated with mixed metal oxides were placed in the electrode compartments. 0.01M Na2SO4
electrolytes were recirculated through them from two 1-liter deposits using a peristaltic pump. Two commercial ion
exchange membranes separated the anolyte and catholyte compartments from the soil in the standard configuration. A
programmable DC: power supply was connected to the electrodes and a computer for data acquisition.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.
The authors acknowledge the financial support from the "Plan Propio de Investigación de la Universidad de Málaga" with project numbers PPIT.UMA.D1; PPIT.UMA.B1.2017/20 and PPIT.UMA.B5.2018/17. This work has also received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045
Analysis of the melon (Cucumis melo) small RNAome by high-throughput pyrosequencing
Abstract Background Melon (Cucumis melo L.) is a commercially important fruit crop that is cultivated worldwide. The melon research community has recently benefited from the determination of a complete draft genome sequence and the development of associated genomic tools, which have allowed us to focus on small RNAs (sRNAs). These are short, non-coding RNAs 21-24 nucleotides in length with diverse physiological roles. In plants, they regulate gene expression and heterochromatin assembly, and control protection against virus infection. Much remains to be learned about the role of sRNAs in melon. Results We constructed 10 sRNA libraries from two stages of developing ovaries, fruits and photosynthetic cotyledons infected with viruses, and carried out high-throughput pyrosequencing. We catalogued and analysed the melon sRNAs, resulting in the identification of 26 known miRNA families (many conserved with other species), the prediction of 84 melon-specific miRNA candidates, the identification of trans-acting siRNAs, and the identification of chloroplast, mitochondrion and transposon-derived sRNAs. In silico analysis revealed more than 400 potential targets for the conserved and novel miRNAs. Conclusion We have discovered and analysed a large number of conserved and melon-specific sRNAs, including miRNAs and their potential target genes. This provides insight into the composition and function of the melon small RNAome, and paves the way towards an understanding of sRNA-mediated processes that regulate melon fruit development and melon-virus interactions.This work was supported by grants AGL2009-07552/AGR, BIO2006-13107 (Ministerio de Ciencia e Innovación, Spain) and MELONOMICS (Fundación Genoma España, Spain).Peer Reviewe
Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis
BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
Desired weight loss and its association with health, health behaviors and perceptions in an adult population with weight excess: One-year follow-up
Background: Metabolic syndrome (MetS) worsens quality of life and increases mortality. Dissatisfaction with weight in patients with MetS may modify the effect of lifestyle interventions to achieve changes in health-related behaviors. Objective: To assess 1-year changes in cardiovascular risk scores, self-perceived general health and health-related behaviors according to observed changes in desired weight loss during the first year of intervention in a large cardiovascular prevention trial. Design: Prospective analysis of the PREDIMED-PLUS trial, including 5,499 adults (55-75 years old) with overweight or obesity at baseline. Methods: The desired weight loss was the difference between ideal and measured weight. Tertiles of change in desired weight loss (1 year vs. baseline) were defined by the following cut-off points: >= 0.0 kg (T1, n = 1,638); 0.0 to -4.0 kg (T2, n = 1,903); <=-4.0 kg (T3, n = 1,958). A food frequency questionnaire assessed diet and the Minnesota-REGICOR questionnaire assessed physical activity. The Framingham equation assessed cardiovascular risks. The changes in the severity of MetS were also assessed. The Beck Depression Inventory assessed depressive symptoms and the SF-36 assessed health-related quality of life. Data were analyzed using general linear models. Results: BMI decreased at T2 and T3 (T1: 0.3, T2: -0.7, T3: -1.9). The most significant improvement in diet quality was observed at T3. Cardiovascular risk decreased at T2 and T3. Mean reductions in MetS severity score were: -0.02 at T1, -0.39 at T2 and -0.78 at T3. The perception of physical health increases in successive tertiles. Conclusions: In older adults with MetS, more ambitious desired weight loss goals were associated with improvements in diet, cardiovascular health and perceived physical health during the first year of a healthy lifestyle intervention programme. Weight dissatisfaction needs to be considered by health professionals
Rheumatoid arthritis response to treatment across IgG1 allotype - anti-TNF incompatibility: a case-only study.
INTRODUCTION: We have hypothesized that incompatibility between the G1m genotype of the patient and the G1m1 and G1m17 allotypes carried by infliximab (INX) and adalimumab (ADM) could decrease the efficacy of these anti-tumor necrosis factor (anti-TNF) antibodies in the treatment of rheumatoid arthritis (RA).
METHODS: The G1m genotypes were analyzed in three collections of patients with RA totaling 1037 subjects. The first, used for discovery, comprised 215 Spanish patients. The second and third were successively used for replication. They included 429 British and Greek patients and 393 Spanish and British patients, respectively. Two outcomes were considered: change in the Disease Activity Score in 28 joint (ΔDAS28) and the European League Against Rheumatism (EULAR) response criteria.
RESULTS: An association between less response to INX and incompatibility of the G1m1,17 allotype was found in the discovery collection at 6 months of treatment (P = 0.03). This association was confirmed in the replications (P = 0.02 and 0.08, respectively) leading to a global association (P = 0.001) that involved a mean difference in ΔDAS28 of 0.4 units between compatible and incompatible patients (2.3 ± 1.5 in compatible patients vs. 1.9 ± 1.5 in incompatible patients) and an increase in responders and decrease in non-responders according to the EULAR criteria (P = 0.03). A similar association was suggested for patients treated with ADM in the discovery collection, but it was not supported by replication.
CONCLUSIONS: Our results suggest that G1m1,17 allotypes are associated with response to INX and could aid improved therapeutic targeting in RA
- …