4,696 research outputs found
Intumescent Coatings as Fire Retardants
Fire-retardant paint, when activated by the heat of fire, reacts to form a thick, low-density, polymeric coating or char layer. Water vapor and sulphur dioxide are released during the intumescent reaction
Multiplex SNP Discrimination
Multiplex hybridization reactions of perfectly matched duplexes and duplexes containing a single basepair mismatch (SNPs) were investigated on DNA microarrays. Effects of duplex length, G-C percentage, and relative position of the SNP on duplex hybridization and SNP resolution were determined. Our theoretical model of multiplex hybridization accurately predicts observed results and implicates target concentration as a critical variable in multiplex SNP detection
Energetics of terrestrial locomotion of the platypus Ornithorhynchus anatinus
© Company of BiologistsThe platypus Ornithorhynchus anatinus Shaw displays specializations in its limb structure for swimming that could negatively affect its terrestrial locomotion. Platypuses walked on a treadmill at speeds of 0.19-1.08 m x s(-1). Video recordings were used for gait analysis, and the metabolic rate of terrestrial locomotion was studied by measuring oxygen consumption. Platypuses used walking gaits (duty factor >0.50) with a sprawled stance. To limit any potential interference from the extensive webbing on the forefeet, platypuses walk on their knuckles. Metabolic rate increased linearly over a 2.4-fold range with increasing walking speed in a manner similar to that of terrestrial mammals, but was low as a result of the relatively low standard metabolic rate of this monotreme. The dimensionless cost of transport decreased with increasing speed to a minimum of 0.79. Compared with the cost of transport for swimming, the metabolic cost for terrestrial locomotion was 2.1 times greater. This difference suggests that the platypus may pay a price in terrestrial locomotion by being more aquatically adapted than other semi-aquatic or terrestrial mammals.F.E. Fish, P.B. Frappell, R.V. Baudinette and P.M. MacFarlan
The Predictive Relationship Between Psychological Capital and Academic Burnout in Postgraduate Students
Purpose: The purpose of this quantitative correlational study was to determine if, or to what extent, the composite and sub-composite categories of Psychological Capital (PsyCap) predict academic burnout in American postgraduate health science students at a university in the Southeastern United States. Methods: The variables of the study were measured by the Psychological Capital Questionnaire (PCQ-24) and the Maslach Burnout Inventory-Student Survey (MBI-SS). A convenience sampling method was used to collect data from the target population, which included a final sample of 90 health science postgraduate students. Results: A simple linear regression analysis revealed that PsyCap was a significant and negative predictor of academic burnout (F(1,88) = 12.00, p \u3c .001, R2 = 0.12; B = -0.28, t(88) = -3.46, p \u3c .001). Additionally, multiple linear regression analysis revealed that only one sub-category of PsyCap, labeled as Optimism, was a significant and negative predictor of academic burnout (F(4,85) = 5.17, p \u3c .001, R2= 0.20; B = -0.90, t(85) = -3.17, p = .002). Conclusion: The findings may be used by higher education instructors, advisors, and administrators in the United States to adopt policies, practices, programs, student advising, and student mentorship that foster PsyCap and Optimism development in students, which may mitigate the risks and consequences of academic burnout
VLBA Observations of G5.89–0.39: OH Masers and Magnetic Field Structure
We present VLBA observations of 1667 MHz OH maser emission from the massive star formation region G5.89-0.39. The observations were phase-referenced, allowing the absolute positions of the masers to be obtained. The 1667 MHz masers have radial velocities that span ~50 km s^(-1) but show little evidence of tracing the bipolar molecular outflow, as has been claimed in previous studies. We identify 23 Zeeman pairs through comparison of masers in left and right circular polarization. Magnetic field strengths range from -2 to +2 mG, and an ordered reversal in magnetic field direction is observed toward the southern region of the UC H II region. We suggest that the velocity and magnetic field structure of the 1667 MHz masers can be explained in the context of a model in which the masers arise in a neutral shell just outside a rapidly expanding ionized shell
Documentos e Debates: Réplica 1 – Clássicos & Formação em Administração: O Que, Quando, Para Que
The structure of the magnetic field in the massive star-forming region W75N
A debated topic in star formation theory is the role of magnetic fields
during the protostellar phase of high-mass stars. It is still unclear how
magnetic fields influence the formation and dynamics of massive disks and
outflows. Most current information on magnetic fields close to high-mass
protostars comes from polarized maser emissions, which allows us to investigate
the magnetic field on small scales by using very long-baseline interferometry.
The massive star-forming region W75N contains three radio continuum sources
(VLA1, VLA2, and VLA3), at three different evolutionary stages, and associated
masers, while a large-scale molecular bipolar outflow is also present. Very
recently, polarization observations of the 6.7 GHz methanol masers at
milliarsecond resolution have been able to probe the strength and structure of
the magnetic field over more than 2000 AU around VLA1. The magnetic field is
parallel to the outflow, suggesting that VLA1 is its powering source. The
observations of water masers at 22 GHz can give more information about the gas
dynamics and the magnetic fields around VLA1 and VLA2. The NRAO Very Long
Baseline Array was used to measure the linear polarization and the
Zeeman-splitting of the 22 GHz water masers in the star-forming region W75N. We
detected 124 water masers, 36 around VLA1 and 88 around VLA2 of W75N, which
indicate two different physical environments around the two sources, where VLA1
is in a more evolved state. The linear polarization of the masers confirms the
tightly ordered magnetic field around VLA1, which is aligned with the
large-scale molecular outflow, and also reveals an ordered magnetic field
around VLA2, which is not parallel to the outflow. [abridged]Comment: 11 pages, 5 figures, 2 Tables, accepted by Astronomy & Astrophysic
The effects of social service contact on teenagers in England
Objective: This study investigated outcomes of social service contact during teenage years.
Method: Secondary analysis was conducted of the Longitudinal Survey of Young People in England (N = 15,770), using data on reported contact with social services resulting from teenagers’ behavior. Outcomes considered were educational achievement and aspiration, mental health, and locus of control. Inverse-probability-weighted regression adjustment was used to estimate the effect of social service contact.
Results: There was no significant difference between those who received social service contact and those who did not for mental health outcome or aspiration to apply to university. Those with contact had lower odds of achieving good exam results or of being confident in university acceptance if sought. Results for locus of control were mixed.
Conclusions: Attention is needed to the role of social services in supporting the education of young people in difficulty. Further research is needed on the outcomes of social services contact
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