1,229 research outputs found
Gravitational conundrum? Dynamical mass segregation versus disruption of binary stars in dense stellar systems
Upon their formation, dynamically cool (collapsing) star clusters will,
within only a few million years, achieve stellar mass segregation for stars
down to a few solar masses, simply because of gravitational two-body
encounters. Since binary systems are, on average, more massive than single
stars, one would expect them to also rapidly mass segregate dynamically.
Contrary to these expectations and based on high-resolution Hubble Space
Telescope observations, we show that the compact, 15-30 Myr-old Large
Magellanic Cloud cluster NGC 1818 exhibits tantalizing hints at the >= 2 sigma
level of significance (> 3 sigma if we assume a power-law secondary-to-primary
mass-ratio distribution) of an increasing fraction of F-star binary systems
(with combined masses of 1.3-1.6 Msun) with increasing distance from the
cluster center, specifically between the inner 10 to 20" (approximately
equivalent to the cluster's core and half-mass radii) and the outer 60 to 80".
If confirmed, this will offer support of the theoretically predicted but thus
far unobserved dynamical disruption processes of the significant population of
'soft' binary systems---with relatively low binding energies compared to the
kinetic energy of their stellar members---in star clusters, which we have
access to here by virtue of the cluster's unique combination of youth and high
stellar density.Comment: Accepted for publication in The Astrophysical Journal; 19 pages in
AASTeX format; 3 figure
A VLT/VIMOS view of two multiple-cluster systems: structure and galaxy properties
We analysed spectroscopic data obtained with VLT-VIMOS for two
multiple-cluster systems, PLCKG and PLCKG, discovered
via their thermal Sunyaev-Zel'dovich signal by . Combining the Optical
spectroscopy, for the redshift determination, and photometric data from galaxy
surveys (SDSS, WISE, DESI), we were able to study the structure of the two
multiple-cluster systems, to determine their nature and the properties of their
member galaxies. We found that the two systems are populated mainly with
passive galaxies and that PLCKG consists of a pair of clusters at
redshift and a background isolated cluster at , whereas
the system PLCKG is a chance association of three independent
clusters at redshifts , , and . We also find
evidence for remaining star formation activity in the highest-redshift cluster
of PLCKG, at .Comment: 12 pages, 9 Figures, 5 Tables. Submitted to A&A, comments are welcom
A Comparison of Print and Cursive Handwriting in Fifth and Sixth Grade Students: A Pilot Study
Background: Handwriting is an important skill to master because handwriting demands take up a significant portion of the school day. Pediatric occupational therapists evaluate and treat children who are experiencing challenges with handwriting; therefore, it is important for practitioners to understand the performance of children using both of these writing styles.
Method: A convenience sample of 36 fifth and sixth grade students participated in the study. Print and cursive handwriting samples were collected on two separate occasions, and a Wilcoxon-Mann-Whitney test was used to examine speed and legibility differences in these writing styles.
Results: Speed in print writing did not differ significantly for gender between the fifth and sixth graders. Cursive writing speed improved significantly for the sixth grade female students compared to the fifth grade female students. Female print legibility scores decreased from the fifth to the sixth grade. Regardless of grade level, the female students were faster with cursive than the male students.
Conclusion: The female students consistently used cursive, and their writing speed increased from one year to the next, as compared to the male students, who did not use a consistent writing style. It is important for occupational therapists to educate teachers and parents on the importance of consistent handwriting instruction and practice
Constraining the mass and redshift evolution of the hydrostatic mass bias using the gas mass fraction in galaxy clusters
The gas mass fraction in galaxy clusters is a quantity which can be used as a robust cosmological probe. It is however subject to various effects from the baryonic physics inside galaxy clusters, which may bias the obtained cosmological constraints. Among different aspects of the baryonic physics, in these proceedings we focus on the impact of the hydrostatic equilibrium assumption. From X-ray measurements of cluster gas fraction in the Planck-ESZ sample, we analyse the hydrostatic mass bias B, constraining a possible mass and redshift evolution of this quantity and its impact on the cosmological constraints. We show a degeneracy between the redshift dependence of the bias and cosmological parameters. In particular we find a 3.8σ evidence for a redshift dependence of the bias when assuming a Planck prior on Ωm. On the other hand, assuming a constant mass bias would lead to the extreme large value of Ωm > 0.860. We however show these results to be depending on the mass and redshift selections inside the main sample. Nevertheless, in all the analyses we find a value for the amplitude of the bias that is consistent with B ∼ 0.8, as expected from hydrodynamical simulations and local measurements, but still in tension with the low value of B ∼ 0.6 derived from the combination of cosmic microwave background primary anisotropies with cluster number counts. We also discuss cosmological constraints obtained from gas fraction data, combined with other probes like cluster number counts
Low-pass shotgun sequencing of the barley genome facilitates rapid identification of genes, conserved non-coding sequences and novel repeats
BACKGROUND: Barley has one of the largest and most complex genomes of all economically important food crops. The rise of new short read sequencing technologies such as Illumina/Solexa permits such large genomes to be effectively sampled at relatively low cost. Based on the corresponding sequence reads a Mathematically Defined Repeat (MDR) index can be generated to map repetitive regions in genomic sequences. RESULTS: We have generated 574 Mbp of Illumina/Solexa sequences from barley total genomic DNA, representing about 10% of a genome equivalent. From these sequences we generated an MDR index which was then used to identify and mark repetitive regions in the barley genome. Comparison of the MDR plots with expert repeat annotation drawing on the information already available for known repetitive elements revealed a significant correspondence between the two methods. MDR-based annotation allowed for the identification of dozens of novel repeat sequences, though, which were not recognised by hand-annotation. The MDR data was also used to identify gene-containing regions by masking of repetitive sequences in eight de-novo sequenced bacterial artificial chromosome (BAC) clones. For half of the identified candidate gene islands indeed gene sequences could be identified. MDR data were only of limited use, when mapped on genomic sequences from the closely related species Triticum monococcum as only a fraction of the repetitive sequences was recognised. CONCLUSION: An MDR index for barley, which was obtained by whole-genome Illumina/Solexa sequencing, proved as efficient in repeat identification as manual expert annotation. Circumventing the labour-intensive step of producing a specific repeat library for expert annotation, an MDR index provides an elegant and efficient resource for the identification of repetitive and low-copy (i.e. potentially gene-containing sequences) regions in uncharacterised genomic sequences. The restriction that a particular MDR index can not be used across species is outweighed by the low costs of Illumina/Solexa sequencing which makes any chosen genome accessible for whole-genome sequence sampling
Integration of the Saline Process on Holistic Patient Care to Improve Student Understanding of Interprofessional Team Roles, Values, and Ethics
Description of the Problem: Healthcare practitioner students currently report feeling underprepared to provide holistic and spiritual care to their patients upon transitioning into practice, and there is currently little data on the efficacy of holistic care-focused interventions on interprofessional outcomes. The goal of this research was to assess the impact of an interprofessional training session on holistic care on student perceptions of interprofessional 1) roles/responsibilities and 2) values/ethics.
The Innovation: A live, interactive interprofessional training session to address holistic patient care was implemented in fall of 2017. Students’ pre- and post-training perceptions of their confidence in study outcomes were assessed using a survey instrument.
Critical Analysis: Significant positive changes were seen in students’ perceived ability to participate in team discussions and clarify misconceptions regarding their role in healthcare following the training. Students had high confidence in interacting ethically at pre-test and sustained that confidence.
Next Steps: Live, interactive educational interventions with skills practice and group discussions can help to increase students’ awareness of team roles and responsibilities, as well as expand their understanding of the values and ethics within healthcare professions
Fabrication of Metal and Alloy Components by Additive Manufacturing: Examples of 3D Materials Science
ObjectiveThis paper provides a brief review of relatively new additive manufacturing technologies for the fabrication of unusual and complex metal and alloy products by laser and electron beam melting. A number of process features and product microstructures are illustrated utilizing 3D optical and transmission electron microscope image compositions representing examples of 3D materials science.MethodsProcessing methods involving electron beam melting (EBM) and a process referred to as direct metal laser sintering (DMLS), often called selective laser melting (SLM) are described along with the use of light (optical) microscopy (OM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) to elucidate microstructural phenomena.ResultsExamples of EBM and SLM studies are presented in 3D image compositions. These include EBM of Ti-6Al-4V, Cu, Co-base superalloy and Inconel 625; and SLM of 17-4 PH stainless steel, Inconel 718 and Inconel 625.Conclusions3D image compositions constituting 3D materials science provide effective visualization for directional solidification-related phenomena associated with the EBM and SLM fabrication of a range of metals and alloys, especially microstructures and microstructural architectures
Knowledge, attitudes and anxiety towards influenza A/H1N1 vaccination of healthcare workers in Turkey
<p>Abstract</p> <p>Background</p> <p>This study aimed to analyze the factors associated with knowledge and attitudes about influenza A (H1N1) and vaccination, and possible relations of these factors with anxiety among healthcare workers (HCW).</p> <p>Methods</p> <p>The study used a cross-sectional descriptive design, and it was carried out between 23 November and 4 December 2009. A total of 300 HCW from two hospitals completed a questionnaire. Data collection tools comprised a questionnaire and the State-Trait Anxiety Inventory (STAI).</p> <p>Results</p> <p>Vaccination rate for 2009 pandemic influenza A(H1N1) among HCW was low (12.7%). Most of the respondents believed the vaccine was not safe and protective. Vaccination refusal was mostly related to the vaccine's side effects, disbelief to vaccine's protectiveness, negative news about the vaccine and the perceived negative attitude of the Prime Minister to the vaccine. State anxiety was found to be high in respondents who felt the vaccine was unsafe.</p> <p>Conclusions</p> <p>HCW considered the seriousness of the outbreak, their vaccination rate was low. In vaccination campaigns, governments have to aim at providing trust, and media campaigns should be used to reinforce this trust as well. Accurate reporting by the media of the safety and efficacy of influenza vaccines and the importance of vaccines for the public health would likely have a positive influence on vaccine uptake. Uncertain or negative reporting about the vaccine is detrimental to vaccination efforts.</p
Activity and Process Stability of Purified Green Pepper (Capsicum annuum) Pectin Methylesterase
Pectin methylesterase (PME) from green bell peppers (Capsicum annuum) was extracted and purified by affinity chromatography on a CNBr-Sepharose-PMEI column. A single protein peak with pectin methylesterase activity was observed. For the pepper PME, a biochemical characterization in terms of molar mass (MM), isoelectric points (pI), and kinetic parameters for activity and thermostability was performed. The optimum pH for PME activity at 22 °C was 7.5, and its optimum temperature at neutral pH was between 52.5 and 55.0 °C. The purified pepper PME required the presence of 0.13 M NaCl for optimum activity. Isothermal inactivation of purified pepper PME in 20 mM Tris buffer (pH 7.5) could be described by a fractional conversion model for lower temperatures (55?57 °C) and a biphasic model for higher temperatures (58?70 °C). The enzyme showed a stable behavior toward high-pressure/temperature treatments. Keywords: Capsicum annuum; pepper; pectin methylesterase; purification; characterization; thermal and high-pressure stabilit
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