151 research outputs found
Performance Test of the Pasquill Stability Classification Scheme
In 1961, Frank Pasquill proposed a method for classifying atmospheric stability based on routinely available surface observations – namely wind speed, cloud cover, and the strength of incoming solar radiation. Stability is classified into six categories: extremely unstable (A); moderately unstable (B); slightly unstable (C); neutral (D); slightly stable (E); and moderately stable (F). These categories are ultimately meant to be used to determine the rate of diffusion of windblown pollutants, but since their inception, the classes have often seen use outside of their originally intended purpose. In this thesis, the performance of the Pasquill scheme is tested in order to determine whether it is appropriate to use it in a non-diffusion related setting. Stability derived using the Pasquill stability scheme is compared to stability derived from temperature lapse rates, using surface and upper air data obtained from the NOAA NCEI for six sites across the Eurasian continent for the years 2000-2010. The Pasquill scheme is found to be biased towards neutral stability, with 57% of all cases determined to be class D – but the actual surface-100m temperature lapse rates were found to be biased towards stable conditions, with 70% of all cases falling into the stable stability range. The Pasquill scheme did perform best under stable conditions, with over 90% the E and F classes occurring when stable conditions were actually present. However, the scheme performed poorly during unstable conditions, correctly predicting an unstable class in only 57% of all unstable cases. The Pasquill method performed the worst under neutral conditions, correctly with neutral conditions present for only 5% of the cases when class D was predicted
MCViNE -- An object oriented Monte Carlo neutron ray tracing simulation package
MCViNE (Monte-Carlo VIrtual Neutron Experiment) is a versatile Monte Carlo
(MC) neutron ray-tracing program that provides researchers with tools for
performing computer modeling and simulations that mirror real neutron
scattering experiments. By adopting modern software engineering practices such
as using composite and visitor design patterns for representing and accessing
neutron scatterers, and using recursive algorithms for multiple scattering,
MCViNE is flexible enough to handle sophisticated neutron scattering problems
including, for example, neutron detection by complex detector systems, and
single and multiple scattering events in a variety of samples and sample
environments. In addition, MCViNE can take advantage of simulation components
in linear-chain-based MC ray tracing packages widely used in instrument design
and optimization, as well as NumPy-based components that make prototypes useful
and easy to develop. These developments have enabled us to carry out detailed
simulations of neutron scattering experiments with non-trivial samples in
time-of-flight inelastic instruments at the Spallation Neutron Source. Examples
of such simulations for powder and single-crystal samples with various
scattering kernels, including kernels for phonon and magnon scattering, are
presented. With simulations that closely reproduce experimental results,
scattering mechanisms can be turned on and off to determine how they contribute
to the measured scattering intensities, improving our understanding of the
underlying physics.Comment: 34 pages, 14 figure
Recent developments of MCViNE and its applications at SNS
MCViNE is an open source, object-oriented Monte Carlo neutron ray-tracing simulation software package. Its design allows for flexible, hierarchical representations of sophisticated instrument components such as detector systems, and samples with a variety of shapes and scattering kernels. Recently this flexible design has enabled several applications of MCViNE simulations at the Spallation Neutron Source (SNS) at Oak Ridge National Lab, including assisting design of neutron instruments at the second target station and design of novel sample environments, as well as studying effects of instrument resolution and multiple scattering. Here we provide an overview of the recent developments and new features of MCViNE since its initial introduction (Jiao et al 2016 Nucl. Instrum. Methods Phys. Res., Sect. A 810, 86–99), and some example applications
Neutron Scattering Signature of Phonon Renormalization in Nickel (II) Oxide
The physics of mutual interaction of phonon quasiparticles with electronic
spin degrees of freedom, leading to unusual transport phenomena of spin and
heat, has been a subject of continuing interests for decades. Despite its
pivotal role in transport processes, the effect of spin-phonon coupling on the
phonon system, especially acoustic phonon properties, has so far been elusive.
By means of inelastic neutron scattering and first-principles calculations,
anomalous scattering spectral intensity from acoustic phonons was identified in
the exemplary collinear antiferromagnetic nickel (II) oxide, unveiling strong
spin-lattice correlations that renormalize the polarization of acoustic phonon.
In particular, a clear magnetic scattering signature of the measured neutron
scattering intensity from acoustic phonons is demonstrated by its momentum
transfer and temperature dependences. The anomalous scattering intensity is
successfully modeled with a modified magneto-vibrational scattering cross
section, suggesting the presence of spin precession driven by phonon. The
renormalization of phonon eigenvector is indicated by the observed
"geometry-forbidden" neutron scattering intensity from transverse acoustic
phonon. Importantly, the eigenvector renormalization cannot be explained by
magnetostriction but instead, it could result from the coupling between phonon
and local magnetization of ions.Comment: Research pape
Animals in our lives: an interactive well-being perspective
Humans have long interacted with animals. Recently, market-based responses to societal challenges, including loneliness and mental well-being include the use of animals. Considerable research concerning consumer–animal relationships has also examined the benefits (micro, meso, and macro) of human-animal interaction and companionship. However, much of this research is fragmented and lacks a broader organizing framework. It also suffers from an anthropomorphic bias, whereby the interests of animals are excluded. To address this, we provide a macromarketing perspective on consumer–animal relations and explore the interdependencies of consumer–animal relationships on consumer, animal, and community well-being. We introduce and apply the Interactive Well-Being framework to four contexts –ranging from private to public consumption spaces– that highlight the interdependencies and systems involved in consumer–animal relationships: (1) co-habitation with animals, (2) emotional support animals, (3) working with animals, and (4) animals in commercial service contexts. We discuss the implications of our framework for the resilience of marketing systems and how the framework aligns with alternative economy development
Treatment of fragile X-associated tremor ataxia syndrome (FXTAS) and related neurological problems
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a progressive neurological disorder that affects older adult carriers, predominantly males, of premutation alleles (55 to 200 CGG repeats) of the fragile X (FMR1) gene. Principal features of FXTAS are intention tremor, ataxia, parkinsonism, cognitive decline, and peripheral neuropathy; ancillary features include, autonomic dysfunction, and psychiatric symptoms of anxiety, depression, and disinhibition. Although controlled trials have not been carried out in individuals with FXTAS, there is a significant amount of anecdotal information regarding various treatment modalities. Moreover, there exists a great deal of evidence regarding the efficacy of various medications for treatment of other disorders (eg, Alzheimer disease) that have substantial phenotypic overlap with FXTAS. The current review summarizes what is currently known regarding the symptomatic treatment, or potential for treatment, of FXTAS
Seatbelt use and risk of major injuries sustained by vehicle occupants during motor-vehicle crashes: A systematic review and meta-analysis of cohort studies
BackgroundIn 2004, a World Health Report on road safety called for enforcement of measures such as seatbelt use, effective at minimizing morbidity and mortality caused by road traffic accidents. However, injuries caused by seatbelt use have also been described. Over a decade after publication of the World Health Report on road safety, this study sought to investigate the relationship between seatbelt use and major injuries in belted compared to unbelted passengers.MethodsCohort studies published in English language from 2005 to 2018 were retrieved from seven databases. Critical appraisal of studies was carried out using the Scottish Intercollegiate Guidelines Network (SIGN) checklist. Pooled risk of major injuries was assessed using the random effects meta-analytic model. Heterogeneity was quantified using I-squared and Tau-squared statistics. Funnel plots and Egger's test were used to investigate publication bias. This review is registered in PROSPERO (CRD42015020309).ResultsEleven studies, all carried out in developed countries were included. Overall, the risk of any major injury was significantly lower in belted passengers compared to unbelted passengers (RR 0.47; 95%CI, 0.29 to 0.80; I-2=99.7; P=0.000). When analysed by crash types, belt use significantly reduced the risk of any injury (RR 0.35; 95%CI, 0.24 to 0.52). Seatbelt use reduces the risk of facial injuries (RR=0.56, 95% CI=0.37 to 0.84), abdominal injuries (RR=0.87; 95% CI=0.78 to 0.98) and, spinal injuries (RR=0.56, 95% CI=0.37 to 0.84). However, we found no statistically significant difference in risk of head injuries (RR=0.49; 95% CI=0.22 to 1.08), neck injuries (RR=0.69: 95%CI 0.07 to 6.44), thoracic injuries (RR 0.96, 95%CI, 0.74 to 1.24), upper limb injuries (RR=1.05, 95%CI 0.83 to 1.34) and lower limb injuries (RR=0.77, 95%CI 0.58 to 1.04) between belted and non-belted passengers.ConclusionIn sum, the risk of most major road traffic injuries is lower in seatbelt users. Findings were inconclusive regarding seatbelt use and susceptibility to thoracic, head and neck injuries during road traffic accidents. Awareness should be raised about the dangers of inadequate seatbelt use. Future research should aim to assess the effects of seatbelt use on major injuries by crash type
ENIGMA and global neuroscience: A decade of large-scale studies of the brain in health and disease across more than 40 countries
This review summarizes the last decade of work by the ENIGMA (Enhancing NeuroImaging Genetics through Meta Analysis) Consortium, a global alliance of over 1400 scientists across 43 countries, studying the human brain in health and disease. Building on large-scale genetic studies that discovered the first robustly replicated genetic loci associated with brain metrics, ENIGMA has diversified into over 50 working groups (WGs), pooling worldwide data and expertise to answer fundamental questions in neuroscience, psychiatry, neurology, and genetics. Most ENIGMA WGs focus on specific psychiatric and neurological conditions, other WGs study normal variation due to sex and gender differences, or development and aging; still other WGs develop methodological pipelines and tools to facilitate harmonized analyses of "big data" (i.e., genetic and epigenetic data, multimodal MRI, and electroencephalography data). These international efforts have yielded the largest neuroimaging studies to date in schizophrenia, bipolar disorder, major depressive disorder, post-traumatic stress disorder, substance use disorders, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorders, epilepsy, and 22q11.2 deletion syndrome. More recent ENIGMA WGs have formed to study anxiety disorders, suicidal thoughts and behavior, sleep and insomnia, eating disorders, irritability, brain injury, antisocial personality and conduct disorder, and dissociative identity disorder. Here, we summarize the first decade of ENIGMA's activities and ongoing projects, and describe the successes and challenges encountered along the way. We highlight the advantages of collaborative large-scale coordinated data analyses for testing reproducibility and robustness of findings, offering the opportunity to identify brain systems involved in clinical syndromes across diverse samples and associated genetic, environmental, demographic, cognitive, and psychosocial factors
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