Context. The study of statistically significant samples of star-forming dwarf galaxies (SFDGs) at different cosmic epochs is essential for the detailed understanding of galaxy assembly and chemical ...evolution. However, the main properties of this large population of galaxies at intermediate redshift are still poorly known. Aims. We present the discovery and spectrophotometric characterization of a large sample of 164 faint (iAB~ 23–25 mag) SFDGs at redshift 0.13 ≤ z ≤ 0.88 selected by the presence of bright optical emission lines in the VIMOS Ultra Deep Survey (VUDS). We investigate their integrated physical properties and ionization conditions, which are used to discuss the low-mass end of the mass-metallicity relation (MZR) and other key scaling relations. Methods. We use optical VUDS spectra in the COSMOS, VVDS-02h, and ECDF-S fields, as well as deep multi-wavelength photometry that includes HST-ACS F814W imaging, to derive stellar masses, extinction-corrected star-formation rates (SFR), and gas-phase metallicities of SFDGs. For the latter, we use the direct method and a Te-consistent approach based on the comparison of a set of observed emission lines ratios with the predictions of detailed photoionization models. Results. The VUDS SFDGs are compact (median re~ 1.2 kpc), low-mass (M∗~ 107–109M⊙) galaxies with a wide range of star-formation rates (SFR(Hα) ~ 10-3–101M⊙/yr) and morphologies. Overall, they show a broad range of subsolar metallicities (12 +log (O/H) =7.26–8.7; 0.04 ≲Z/Z⊙≲ 1). Nearly half of the sample are extreme emission-line galaxies (EELGs) characterized by high equivalent widths and emission line ratios indicative of higher excitation and ionization conditions. The MZR of SFDGs shows a flatter slope compared to previous studies of galaxies in the same mass range and redshift. We find the scatter of the MZR is partly explained in the low mass range by varying specific SFRs and gas fractions amongst the galaxies in our sample. In agreement with recent studies, we find the subclass of EELGs to be systematically offset to lower metallicity compared to SFDGs at a given stellar mass and SFR, suggesting a younger starburst phase. Compared with simple chemical evolution models we find that most SFDGs do not follow the predictions of a “closed-box” model, but those from a gas-regulating model in which gas flows are considered. While strong stellar feedback may produce large-scale outflows favoring the cessation of vigorous star formation and promoting the removal of metals, younger and more metal-poor dwarfs may have recently accreted large amounts of fresh, very metal-poor gas, that is used to fuel current star formation.
Although silver nanoparticles (AgNPs) are widely disseminated and show great potential in the biomedical field, there is a recognized need to better understand their action at the metabolic and ...functional levels. In this work, we have used NMR metabolomics, together with conventional clinical chemistry and histological examination, to characterize multi-organ and systemic metabolic responses to AgNPs intravenously administered to mice at 8 mg/kg body weight (a dose not eliciting overt toxicity). The major target organs of AgNPs accumulation, liver and spleen, showed the greatest metabolic changes, in a clear 2-stage response. In particular, the liver of dosed mice was found to switch from glycogenolysis and lipid storage, at 6 h postinjection, to glycogenesis and lipolysis, at subsequent times up to 48 h. Moreover, metabolites related to antioxidative defense, immunoregulation and detoxification seemed to play a crucial role in avoiding major hepatic damage. The spleen showed several early changes, including depletion of several amino acids, possibly reflecting impairment of hemoglobin recycling, while only a few differences remained at 48 h postinjection. In the heart, the metabolic shift towards TCA cycle intensification and increased ATP production possibly reflected a beneficial adaptation to the presence of AgNPs. On the other hand, the TCA cycle appeared to be down regulated in the lungs of injected mice, which showed signs of inflammation. Thekidneys showed the mildest metabolic response to AgNPs. Overall, this study has shown that NMR metabolomics is a powerful tool to monitor invivo metabolic responses to nanoparticles, revealing unforeseen effects.
We report the characterization of two planet candidates detected by the Transiting Exoplanet Survey Satellite (TESS), TOI-1199 b and TOI-1273 b, with periods of 3.7 and 4.6 days, respectively. ...Follow-up observations for both targets, which include several ground-based light curves, confirmed the transit events. High-precision radial velocities from the SOPHIE spectrograph revealed signals at the expected frequencies and phases of the transiting candidates and allowed mass determinations with a precision of 8.4% and 6.7% for TOI-1199 b and TOI-1273 b, respectively. The planetary and orbital parameters were derived from a joint analysis of the radial velocities and photometric data. We find that the planets have masses of 0.239 ± 0.020 M J and 0.222 ± 0.015 M J and radii of 0.938 ± 0.025 R J and 0.99 ± 0.22 R J , respectively. The grazing transit of TOI-1273 b translates to a larger uncertainty in its radius, and hence also in its bulk density, compared to TOI-1199 b. The inferred bulk densities of 0.358 ± 0.041 g cm −3 and 0.28 ± 0.11 g cm −3 are among the lowest known for exoplanets in this mass range, which, considering the brightness of the host stars ( V ≈11 mag), render them particularly amenable to atmospheric characterization via the transit spectroscopy technique. The better constraints on the parameters of TOI-1199 b provide a transmission spectroscopy metric of 134 ± 17, making it the better suited of the two planets for atmospheric studies.
Cardiovascular diseases (CVD) remain the biggest cause of deaths worldwide and a major socio-economic impact to society. In this work, we conducted an unbiased exploratory analysis of the large-scale ...lipidome in human plasma samples from patients with fatal and non-fatal CVD from large cohorts. The exploratory analysis included data from 10,349 individuals from 20 countries in Asia, Australasia, Europe and North America (ADVANCE cohort), and thus representative of the worldwide population. Through the analysis of hazard ratios (HR), we found 306 lipids relevant in CV Death and 294 lipids relevant in CV Events of which 262 lipids were common to fatal and non-fatal events followed over time (3, 5 and 8 years). Our exploratory analysis reveals that, over time, the plasma lipid signature found in non-fatal CVD events is similar to that preceding CVD death. Among the common lipid signature, we found that sphingolipids (HexCer, SM, Cer and other glycosphingolipids) and phospholipids (PC and PE) were strongly associated with CVD events outcome, while polyunsaturated plasmenyl PC and PE lipids were inversely associated with CV outcome. The restricted panel of specific lipids has the potential to improve CVD risk stratification and management, and significantly reduce the time involved in the analysis and data treatment in low-resolution MS instruments making plasma lipidomics a cost-efficient approach for clinical scenario. In our view, once standardized clinical, analytical and data reporting guidelines are implemented worldwide, lipid-based discriminators can be routinely applied in the CVD risk stratification and improve the performance of current clinical, biochemical and imaging diagnostic tools assisting the decision-making process particularly in patients with multiple co-morbidities.
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•Clinical and biochemical markers are unable to stratify patients at intermediate risk.•We pursued an exploratory analysis of large lipidome in large sampling group datasets.•Our exploratory analysis revealed lipid signature of CV Events preceded CV Death.•Panel of 29 discriminant lipids could speed-up decision-making process.•CVD lipid-based marker validation rely on standardization of lipid pipeline protocols.
A comparative study on concept drift detectors Gonçalves, Paulo M.; de Carvalho Santos, Silas G.T.; Barros, Roberto S.M. ...
Expert systems with applications,
12/2014, Letnik:
41, Številka:
18
Journal Article
Recenzirano
•We evaluated eight different concept drift detectors.•A 2k factorial design was used to indicate the best parameters for each method.•Tests compared accuracy, evaluation time, false alarm and miss ...detection rates.•A Mahalanobis distance is proposed as a metric to compare drift methods.•DDM was the method that presented the best average results in all tested datasets.
In data stream environments, drift detection methods are used to identify when the context has changed. This paper evaluates eight different concept drift detectors (ddm, eddm, pht, stepd, dof, adwin, Paired Learners, and ecdd) and performs tests using artificial datasets affected by abrupt and gradual concept drifts, with several rates of drift, with and without noise and irrelevant attributes, and also using real-world datasets. In addition, a 2k factorial design was used to indicate the parameters that most influence performance which is a novelty in the area. Also, a variation of the Friedman non-parametric statistical test was used to identify the best methods. Experiments compared accuracy, evaluation time, as well as false alarm and miss detection rates. Additionally, we used the Mahalanobis distance to measure how similar the methods are when compared to the best possible detection output. This work can, to some extent, also be seen as a research survey of existing drift detection methods.
The aim of the present paper is to propose a simple methodology to predict the failure pressure of wall loss defect metallic pipes reinforced with a polymer based composite repair system. 80% wall ...loss defects were manufactured into the pristine pipeline specimen and the failure pressure of the repaired pipeline was determined using hydrostatic tests and validated with the proposed methodology. The proposed methodology defines a simple expression which allows to estimate the failure pressure using only the elastic properties of materials. A more conservative value of failure pressure was obtained by using this methodology as compared to the ISO/TS 24817 standard. However, the failure pipe exhibited a plastic deformation at far away from the defect region, consequently this behaviour needs to be considered in the failure analysis for an accurate prediction of failure pressure.
Rheumatic fever (RF) and rheumatic heart disease (RHD) follow untreated S. pyogenes throat infections in children who present susceptible genes that favor the development of autoimmune reactions. In ...this review, we focus on the genes that confer susceptibility and on the autoimmune reactions that occur due to molecular mimicry between human-tissue proteins and streptococcal M protein. Polyarthritis is the initial manifestation, which can evolve to carditis and severe valve damage; these culminate in rheumatic heart disease (RHD) or Sydenham's chorea, which affects the central nervous system. A perspective on vaccine development to prevent the disease is also discussed.
Living shorelines (LS) are a nature‐based restoration technique that aims to stabilize shorelines while enhancing multiple ecosystem services. In particular, LS are frequently promoted as beneficial ...for enhancing essential coastal habitats for fish and mobile crustaceans (nekton). In this study, we aimed to assess the effects of LS on nekton habitat across eight LS restoration sites in coastal Alabama, U.S.A., by applying widely‐used community metrics. Nekton abundance, species richness, evenness, and diversity tended to be higher in LS and adjacent unrestored control sites than along nearby hardened shorelines. Community metrics showed no clear effect of LS compared to their adjacent controls, with substantial among‐site variation masking any restoration effect. While this may suggest an ecological equivalence between restored and control sites, there are other possible interpretations; that a lack of difference reflects sampling the same populations at nearby control and restored sites, that differences do exist but sampling effort was insufficient to detect them, or that community metrics may be too insensitive for comparing the effects of various restoration approaches on nekton habitat quality. Further exploration of individual‐based metrics such as growth and condition of key species is warranted, as these may be more sensitive for assessing restoration outcomes and guiding future project designs.
Abstract
We analyze a sample of
z
-dropout galaxies in the CANDELS GOODS South and UDS fields that have been targeted by a dedicated spectroscopic campaign aimed at detecting their Ly
α
line. Deep ...IRAC observations at 3.6 and 4.5
μ
m are used to determine the strength of optical emission lines affecting these bands at
z
∼ 6.5–6.9 in order to (1) investigate possible physical differences between Ly
α
emitting and non-emitting sources; (2) constrain the escape fraction of ionizing photons; and (3) provide an estimate of the specific star formation rate at high redshifts. We find evidence of strong O
iii
+H
β
emission in the average (stacked) SEDs of galaxies both with and without Ly
α
emission. The blue IRAC 3.6–4.5 color of the stack with detected Ly
α
line can be converted into a rest-frame equivalent width EW(O
iii
+H
β
) =
Å assuming a flat intrinsic stellar continuum. This strong optical line emission enables a first estimate of
on the escape fraction of ionizing photons from Ly
α
detected objects. The objects with no Ly
α
line show less extreme EW(O
iii
+H
β
) =
Å, suggesting different physical conditions of the H
ii
regions with respect to Ly
α
-emitting ones, or a larger
. The latter case is consistent with a combined evolution of
and the neutral hydrogen fraction as an explanation of the lack of bright Ly
α
emission at
z
> 6. A lower limit on the specific star formation rate, SSFR > 9.1 Gyr
−1
for
galaxies at these redshifts can be derived from the spectroscopically confirmed sample.
•Easy obtention of Cu3(MoO4)2(OH)2 by sonochemistry route at room temperature.•Urchin-like morphology was obtained in aqueous solution using the sonochemistry method for copper molybdate.•High ...conversion rate in the esterification of oleic acid using the Cu3(MoO4)2(OH)2 as a solid catalyst.
Copper molybdate nanoplates were synthesized by a sonochemical process at room temperature, which we report as a simple and cost-effective route. Structural analysis of the material by the Rietveld method of X-ray diffraction (XRD) data revealed lindgrenite Cu3(MoO4)2(OH)2 in a single-phase structure. All the vibrational modes characteristic of the space group were identified by Raman vibrational and near-infrared (NIR) spectroscopies. The profile obtained for N2 adsorption/desorption was type III hysteresis, characteristic of mesoporous materials, with a surface area of 70.77(1) m2 g−1. The micrographs of the material obtained by scanning electron microscopy showed nanoplates with nanometric sizes and an anisotropic growth aspect. The catalytic activity of lindgrenite was evaluated by esterifying oleic acid with methanol, showing high conversion rate to methyl oleate and good catalyst stability after seven recycling cycles. Above all, the best catalytic performance was reached when we optimized parameters such as oleic acid:methanol molar ratio of 1:5, 5% of catalyst dosage, and reaction time of 5 h, resulting in 98.38% of conversion at 413 K. Therefore, sonochemically synthesized lindgrenite proved to be a high potential material for biofuel production by oleic acid esterification.
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