4,378 research outputs found
Substellar Objects in Nearby Young Clusters (SONYC) VIII: Substellar population in Lupus 3
SONYC -- Substellar Objects in Nearby Young Clusters -- is a survey program
to investigate the frequency and properties of substellar objects in nearby
star-forming regions. We present a new imaging and spectroscopic survey
conducted in the young (~1 Myr), nearby (~200 pc) star-forming region Lupus 3.
Deep optical and near-infrared images were obtained with MOSAIC-II and NEWFIRM
at the CTIO-4m telescope, covering ~1.4 sqdeg on the sky. The i-band
completeness limit of 20.3 mag is equivalent to 0.009-0.02 MSun, for Av \leq 5.
Photometry and 11-12 yr baseline proper motions were used to select candidate
low-mass members of Lupus 3. We performed spectroscopic follow-up of 123
candidates, using VIMOS at the Very Large Telescope (VLT), and identify 7
probable members, among which 4 have spectral type later than M6.0 and Teff
\leq 3000K, i.e. are probably substellar in nature. Two of the new probable
members of Lupus 3 appear underluminous for their spectral class and exhibit
emission line spectrum with strong Halpha or forbidden lines associated with
active accretion. We derive a relation between the spectral type and effective
temperature: Teff=(4120 +- 175) - (172 +- 26) x SpT, where SpT refers to the M
spectral subtype between 1 and 9. Combining our results with the previous works
on Lupus 3, we show that the spectral type distribution is consistent with that
in other star forming regions, as well as is the derived star-to-BD ratio of
2.0-3.3. We compile a census of all spectroscopically confirmed low-mass
members with spectral type M0 or later.Comment: Accepted by Astrophysical Journa
Prosociality and life satisfaction: a daily-diary investigation among Spanish university students
With a diary study, we tested the positive effect of prosociality on life satisfaction. Fifty-six Spanish undergraduate students (45 females; Mage = 21.08 years) rated their life satisfaction, prosociality, self-esteem, and physical appearance for 5 consecutive days. Multilevel results indicated that within-individual positive deviations in prosociality (i.e., behaving more prosocial than usual) were uniquely and significantly associated with higher life satisfaction on that specific day. Students’ self-esteem, physical appearance, and positive daily events were also predictive of life satisfaction. Exploratory analyses revealed that the positive effect of prosociality on life satisfaction was significant only for those students with low or medium levels of satisfaction with their physical appearance. The findings are discussed in relation to the individual determinants of subjective well-being during early adulthood
Bibliometrics as a Tool for Environmental Management at the University of Havana
Within the framework of the University of Havana Environment Network (Red MA-UH), much environmental research is carried out, but most of it is never implemented or applied due to poor visibility and a lack of efficient strategic alliances. Today, the results of much of this research become either grey literature or Cuban publications with poor visibility, and therefore they can’t be used for solving environmental problems affecting society. Nevertheless, this research could be used to help solve socio-environmental problems if decision-makers and international organizations were made aware of the results and provided funding to put them into practice. Research results are increasingly being disseminated on an international scale, so their visibility can be enhanced and funding and scientific collaboration can be gotten more easily, allowing the University of Havana Environment Network’s research to have the desired social effects. The present work is aimed at examining high-impact publications included in the Scimago Journal & Country Rank (SJCR) portal, specifically in the field of environmental sciences. Metrical indicators were used to show the University of Havana Environment Network how to make its research results more visible by identifying international high-impact publications in the environmental sciences, to enhance the visibility of research carried out at the University of Havana, which contributes, in turn, to implementation in environmental management, rational use and equitable distribution of resources, and the promotion of local development by means of environmental management strategies, guaranteeing a harmonious relationship between society and natur
Defect-hydrogen interaction in Al alloys: Challenges and benefits revealed by ab initio calculations
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An X-ray study of the SNR G344.7-0.1 and the central object CXOU J170357.8-414302
Aims. We report results of an X-ray study of the supernova remnant (SNR)
G344.7-0.1 and the point-like X-ray source located at the geometrical center of
the SNR radio structure. Methods. The morphology and spectral properties of the
remnant and the central X-ray point-like source were studied using data from
the XMM-Newton and Chandra satellites. Archival radio data and infrared Spitzer
observations at 8 and 24 m were used to compare and study its multi-band
properties at different wavelengths. Results. The XMM-Newton and Chandra
observations reveal that the overall X-ray emission of G344.7-0.1 is extended
and correlates very well with regions of bright radio and infrared emission.
The X-ray spectrum is dominated by prominent atomic emission lines. These
characteristics suggest that the X-ray emission originated in a thin thermal
plasma, whose radiation is represented well by a plane-parallel shock plasma
model (PSHOCK). Our study favors the scenario in which G344.7-0.1 is a 6 x 10^3
year old SNR expanding in a medium with a high density gradient and is most
likely encountering a molecular cloud on the western side. In addition, we
report the discovery of a soft point-like X-ray source located at the
geometrical center of the radio SNR structure. The object presents some
characteristics of the so-called compact central objects (CCO). However, its
neutral hydrogen absorption column (N_{H}) is inconsistent with that of the
SNR. Coincident with the position of the source, we found infrared and optical
objects with typical early-K star characteristics. The X-ray source may be a
foreground star or the CCO associated with the SNR. If this latter possibility
were confirmed, the point-like source would be the farthest CCO detected so far
and the eighth member of the new population of isolated and weakly magnetized
neutron stars.Comment: 9 pages, 8 figures, accepted for publication in Astronomy and
Astrophysics. Higher resolution figures can be seen on A&
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Heparin versus 0.9% sodium chloride locking for prevention of occlusion in central venous catheters in adults
Background
Intermittent locking of central venous catheters (CVCs) is undertaken to help maintain their patency. There are systematic variations in care: some practitioners use heparin (at different concentrations), whilst others use 0.9% NaCl (normal saline). This review looks at the effectiveness and safety of intermittent locking with heparin compared to 0.9% NaCl to see if the evidence establishes whether one is better than the other. This work is an update of a review first published in 2014.
Objectives
To assess the effectiveness and safety of intermittent locking of CVCs with heparin versus normal saline (NS) in adults to prevent occlusion.
Search methods
The Cochrane Vascular Information Specialist (CIS) searched the Specialised Register (last searched 11 June 2018) and the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 5). Searches were also carried out in MEDLINE, Embase, CINAHL, and clinical trials databases (11 June 2018).
Selection criteria
We included randomised controlled trials in adults ≥ 18 years of age with a CVC that compared intermittent locking with heparin at any concentration versus NS. We applied no restriction on language.
Data collection and analysis
Two review authors independently selected trials, assessed quality, and extracted data. We contacted trial authors to retrieve additional information, when necessary.We carried out statistical analysis using ReviewManager 5 and assessed the overall quality of the evidence supporting assessed outcomes using GRADE. We carried out prespecified subgroup analysis.
Main results
We identified five new studies for this update (six prior studies were included in the original review), bringing the number of eligible studies to 11, with a total of 2392 participants. We noted differences in methods used by the included studies and variation in heparin concentrations (10 to 5000 IU/mL), time to follow-up (1 to 251.8 days), and the unit of analysis used (participant, catheter, line access). Combined results fromthese studies showed fewer occlusions with heparin than with NS (risk ratio (RR) 0.70, 95%confidence interval (CI) 0.51 to 0.95; P = 0.02; 1672 participants; 1025 catheters from 10 studies; I² = 14%) and provided very low-quality evidence. We carried out subgroup analysis by unit of analysis (testing for subgroup differences (P = 0.23; I² = 30.3%). When the unit of analysis was the participant, results show no clear differences in all occlusions between heparin and NS (RR 0.79, 95% CI 0.58 to 1.08; P = 0.15; 1672 participants; seven studies). Subgroup analysis using the catheter as the unit of analysis shows fewer occlusions with heparin use (RR 0.53, 95% CI 0.29 to 0.95; P = 0.03; 1025 catheters; three studies). When the unit of analysis was line access, results show no clear differences in occlusions between heparin and NS (RR 1.08, 95% CI 0.84 to 1.40; 770 line accesses; one study). We found no clear differences in the duration of catheter patency (mean difference (MD) 0.44 days, 95% CI -0.10 to 0.99; P = 0.11; 1036 participants; 752 catheters; six studies; low-quality evidence). We found no clear evidence of a difference in the following: CVC-related sepsis (RR 0.74, 95% CI 0.03 to 19.54; P = 0.86; 1097 participants; two studies; low-quality evidence); mortality (RR 0.76, 95% CI 0.44 to 1.31; P = 0.33; 1100 participants; three studies; low-quality evidence); haemorrhage at any site (RR 1.32, 95% CI 0.57 to 3.07; P = 0.52; 1245 participants; four studies; moderatequality evidence); or heparin-induced thrombocytopaenia (RR 0.21, 95% CI 0.01 to 4.27; P = 0.31; 443 participants; three studies; low-quality evidence). Themain reasons for downgrading the quality of evidencewere unclear allocation concealment, imprecision, and suspicion of publication bias.
Authors’ conclusions
Given the very low quality of the evidence, we are uncertain whether intermittent locking with heparin results in fewer occlusions than intermittent locking with NS. Low-quality evidence suggests that heparin may have little or no effect on catheter patency. Although we found no evidence of differences in safety (sepsis, mortality, or haemorrhage), the combined trials are not powered to detect rare adverse events such as heparin-induced thrombocytopaenia
Selective maintenance of Drosophila tandemly arranged duplicated genes during evolution
Genes occurring in conserved, tandemly-arrayed clusters in Drosophila melanogaster are co-expressed to a much higher extent than other duplicated genes
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