9,897 research outputs found
The psychological distress of the young driver: a brief report
Objective: To explore the role of psychological distress in the self-reported risky driving of young novice drivers. Design: Cross-sectional online survey of 761 tertiary students aged 17-25 years with an intermediate (Provisional) driving licence who completed Kessler’s Psychological Distress Scale and the Behaviour of Young Novice Drivers Scale. Setting: Queensland, Australia, August-October 2009. Main outcome measures: Psychological distress, risky driving. Results: Regression analyses revealed that psychological distress uniquely explained 8.5% of the variance in young novice’s risky driving, with adolescents experiencing psychological distress also reporting higher levels of risky driving. Psychological distress uniquely explained a significant 6.7% and 9.5% of variance in risky driving for males and females respectively. Conclusions: Medical practitioners treating adolescents who have been injured through risky behaviour need to aware of the potential contribution of psychological distress, whilst mental health professionals working with adolescents experiencing psychological distress need to be aware of this additional source of potential harm. The nature of the causal relationships linking psychological distress and risky driving behaviour are not yet fully understood, indicating a need for further research so that strategies such as screening can be investigated
Understanding the magnetic resonance spectrum of nitrogen vacancy centers in an ensemble of randomly-oriented nanodiamonds
Nanodiamonds containing nitrogen vacancy (NV-) centers show promise for a
number of emerging applications including targeted in vivo imaging and
generating nuclear spin hyperpolarization for enhanced NMR spectroscopy and
imaging. Here, we develop a detailed understanding of the magnetic resonance
behavior of NV- centers in an ensemble of nanodiamonds with random crystal
orientations. Two-dimensional optically detected magnetic resonance
spectroscopy reveals the distribution of energy levels, spin populations, and
transition probabilities that give rise to a complex spectrum. We identify
overtone transitions that are inherently insensitive to crystal orientation and
give well-defined transition frequencies that access the entire nanodiamond
ensemble. These transitions may be harnessed for high-resolution imaging and
generation of nuclear spin hyperpolarization. The data are well described by
numerical simulations from the zero- to high-field regimes, including the
intermediate regime of maximum complexity. We evaluate the prospects of
nanodiamond ensembles specifically for nuclear hyperpolarization and show that
frequency-swept dynamic nuclear polarization may transfer a large amount of the
NV- center's hyperpolarization to nuclear spins by sweeping over a small region
of its spectrum.Comment: 6 pages, 5 figure
Evaluation Framework for Water Quality Trading Programs in the Chesapeake Bay Watershed
Water quality trading programs are being proposed and implemented across the US in a variety of forms and with differing objectives. The programs being proposed and implemented in the Chesapeake Bay region are no exception. Against this background the Chesapeake Bay Program's Scientific and Technical Advisory Committee and the Mid-Atlantic Water Program requested a general framework to inform and guide the evaluation of the performance trading programs. This resulting report was developed by a workgroup comprised of ten individuals with extensive experience in the study, design, and evaluation of trading programs. While the impetus for this report was to improve evaluation of trading programs in the Chesapeake Bay region, the evaluation framework is broad enough to apply to trading programs in general
The same, but different: Stochasticity in binary destruction
Observations of binaries in clusters tend to be of visual binaries with
separations of 10s - 100s au. Such binaries are 'intermediates' and their
destruction or survival depends on the exact details of their individual
dynamical history. We investigate the stochasticity of the destruction of such
binaries and the differences between the initial and processed populations
using N-body simulations. We concentrate on Orion Nebula Cluster-like clusters,
where the observed binary separation distribution ranges from 62 - 620 au.
We find that, starting from the same initial binary population in
statistically identical clusters, the number of intermediate binaries that are
destroyed after 1 Myr can vary by a factor of >2, and that the resulting
separation distributions can be statistically completely different in initially
substructured clusters. We also find that the mass ratio distributions are
altered (destroying more low mass ratio systems), but not as significantly as
the binary fractions or separation distributions. We conclude that finding very
different intermediate (visual) binary populations in different clusters does
not provide conclusive evidence that the initial populations were different.Comment: 11 pages, 7 figures, accepted for publication in MNRA
Detection of intermediates and kinetic control during assembly of bacteriophage P22 procapsid
Bacteriophage P22 serves as a model for the assembly and maturation of other icosahedral double-stranded DNA viruses. P22 coat and scaffolding proteins assemble in vitro
into an icosahedral procapsid, which then expands during DNA packaging (maturation). Efficient in vitro assembly makes this system suitable for design and production of
monodisperse spherical nanoparticles (diameter ≈50 nm). In this work we explore the possibility of controlling the outcome of assembly by scaffolding protein engineering. The
scaffolding protein exists in monomer-dimer-tetramer equilibrium. We address the role of monomers and dimers in assembly by using three different scaffolding proteins with altered monomer-dimer equilibrium (weak dimer, covalent dimer, monomer). The progress and outcome of assembly was monitored by time-resolved X-ray scattering which allowed us to distinguish between closed shells and incomplete assembly intermediates. Binding of scaffolding monomer activates the coat protein for assembly. Excess dimeric scaffolding protein resulted in rapid nucleation and kinetic trapping yielding incomplete shells. Addition
of monomeric wild type scaffold with excess coat protein completed these metastable shells. Thus, the monomeric scaffolding protein plays an essential role in the elongation phase by activating the coat and effectively lowering its critical concentration for assembly
Testing the universality of star formation - II. Comparing separation distributions of nearby star-forming regions and the field
We have measured the multiplicity fractions and separation distributions of
seven young star-forming regions using a uniform sample of young binaries. Both
the multiplicity fractions and separation distributions are similar in the
different regions. A tentative decline in the multiplicity fraction with
increasing stellar density is apparent, even for binary systems with
separations too close (19-100au) to have been dynamically processed. The
separation distributions in the different regions are statistically
indistinguishable over most separation ranges, and the regions with higher
densities do not exhibit a lower proportion of wide (300-620au) relative to
close (62-300au) binaries as might be expected from the preferential
destruction of wider pairs. Only the closest (19-100au) separation range, which
would be unaffected by dynamical processing, shows a possible difference in
separation distributions between different regions. The combined set of young
binaries, however, shows a distinct difference when compared to field binaries,
with a significant excess of close (19-100au) systems among the younger
binaries. Based on both the similarities and differences between individual
regions, and between all seven young regions and the field, especially over
separation ranges too close to be modified by dynamical processing, we conclude
that multiple star formation is not universal and, by extension, the star
formation process is not universal.Comment: accepted for publication in MNRA
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