1,134 research outputs found
Road lighting and distraction whilst driving: Establishing the significant types of distraction
There is a body of research showing how changes in lighting conditions affect hazard detection in the context of driving after dark. There is a separate body of research showing that driving is impaired by distraction. The two have yet to be integrated: this is critical for lighting design recommendations because giving consideration to distraction may affect the optimal conditions established in lighting studies. A first step in that process is establishing the critical type(s) of distraction that might then be simulated in lighting research. This paper reviews evidence for the prevalence of driving distractions as recorded by two methods: interviews with drivers following collision and observation of drivers on real roads. These data suggest that auditory distractions such as conversation with passengers and listening to music are prevalent distractions, and are therefore appropriate distractions to incorporate in further research of lighting and hazard detection experiments
On Inflation with Non-minimal Coupling
A simple realization of inflation consists of adding the following operators
to the Einstein-Hilbert action: (partial phi)^2, lambda phi^4, and xi phi^2 R,
with xi a large non-minimal coupling. Recently there has been much discussion
as to whether such theories make sense quantum mechanically and if the inflaton
phi can also be the Standard Model Higgs. In this note we answer these
questions. Firstly, for a single scalar phi, we show that the quantum field
theory is well behaved in the pure gravity and kinetic sectors, since the
quantum generated corrections are small. However, the theory likely breaks down
at ~ m_pl / xi due to scattering provided by the self-interacting potential
lambda phi^4. Secondly, we show that the theory changes for multiple scalars
phi with non-minimal coupling xi phi dot phi R, since this introduces
qualitatively new interactions which manifestly generate large quantum
corrections even in the gravity and kinetic sectors, spoiling the theory for
energies > m_pl / xi. Since the Higgs doublet of the Standard Model includes
the Higgs boson and 3 Goldstone bosons, it falls into the latter category and
therefore its validity is manifestly spoiled. We show that these conclusions
hold in both the Jordan and Einstein frames and describe an intuitive analogy
in the form of the pion Lagrangian. We also examine the recent claim that
curvature-squared inflation models fail quantum mechanically. Our work appears
to go beyond the recent discussions.Comment: 14 pages, 2 figures. Version 2: Clarified findings and improved
wording. Elaborated important sections and removed an unnecessary section.
Added references. Version 3: Updated towards JHEP version. Version 4: Final
JHEP versio
Effective theories of single field inflation when heavy fields matter
We compute the low energy effective field theory (EFT) expansion for
single-field inflationary models that descend from a parent theory containing
multiple other scalar fields. By assuming that all other degrees of freedom in
the parent theory are sufficiently massive relative to the inflaton, it is
possible to derive an EFT valid to arbitrary order in perturbations, provided
certain generalized adiabaticity conditions are respected. These conditions
permit a consistent low energy EFT description even when the inflaton deviates
off its adiabatic minimum along its slowly rolling trajectory. By generalizing
the formalism that identifies the adiabatic mode with the Goldstone boson of
this spontaneously broken time translational symmetry prior to the integration
of the heavy fields, we show that this invariance of the parent theory dictates
the entire non-perturbative structure of the descendent EFT. The couplings of
this theory can be written entirely in terms of the reduced speed of sound of
adiabatic perturbations. The resulting operator expansion is distinguishable
from that of other scenarios, such as standard single inflation or DBI
inflation. In particular, we re-derive how certain operators can become
transiently strongly coupled along the inflaton trajectory, consistent with
slow-roll and the validity of the EFT expansion, imprinting features in the
primordial power spectrum, and we deduce the relevant cubic operators that
imply distinct signatures in the primordial bispectrum which may soon be
constrained by observations.Comment: (v1) 25 pages, 1 figure; (v2) references added and typos corrected,
to appear in Journal of High Energy Physic
EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical
We identify the effective theory describing inflationary super-Hubble scales and show it to be a special case of effective field theories appropriate to open systems. Open systems allow information to be exchanged between the degrees of freedom of interest and those that are integrated out, such as for particles moving through a fluid. Strictly speaking they cannot in general be described by an effective lagrangian; rather the appropriate `low-energy' limit is instead a Lindblad equation describing the evolution of the density matrix of the slow degrees of freedom. We derive the equation relevant to super-Hubble modes of quantum fields in near-de Sitter spacetimes and derive two implications. We show the evolution of the diagonal density-matrix elements quickly approaches the Fokker-Planck equation of Starobinsky's stochastic inflationary picture. This provides an alternative first-principles derivation of this picture's stochastic noise and drift, as well as its leading corrections. (An application computes the noise for systems with a sub-luminal sound speed.) We argue that the presence of interactions drives the off-diagonal density-matrix elements to zero in the field basis. This shows why the field basis is the `pointer basis' for the decoherence of primordial quantum fluctuations while they are outside the horizon, thus allowing them to re-enter as classical fluctuations, as assumed when analyzing CMB data. The decoherence process is efficient, occurring after several Hubble times even for interactions as weak as gravitational-strength. Crucially, the details of the interactions largely control only the decoherence time and not the nature of the final late-time stochastic state, much as interactions can control the equilibration time for thermal systems but are largely irrelevant to the properties of the resulting equilibrium state
Measuring oxygen access: lessons from health facility assessments in Lagos, Nigeria
The COVID-19 pandemic has highlighted global oxygen system deficiencies and revealed gaps in how we understand and measure āoxygen accessā. We present a case study on oxygen access from 58 health facilities in Lagos state, Nigeria. We found large differences in oxygen access between facilities (primary vs secondary, government vs private) and describe three key domains to consider when measuring oxygen access: availability, cost, use. Of 58 facilities surveyed, 8 (14%) of facilities had a functional pulse oximeter. Oximeters (N=27) were typically located in outpatient clinics (12/27, 44%), paediatric ward (6/27, 22%) or operating theatre (4/27, 15%). 34/58 (59%) facilities had a functional source of oxygen available on the day of inspection, of which 31 (91%) facilities had it available in a single ward area, typically the operating theatre or maternity ward. Oxygen services were free to patients at primary health centres, when available, but expensive in hospitals and private facilities, with the median cost for 2ādays oxygen 13ā000 (US77) Naira, respectively. We obtained limited data on the cost of oxygen services to facilities. Pulse oximetry use was low in secondary care facilities (32%, 21/65 patients had SpO2 documented) and negligible in private facilities (2%, 3/177) and primary health centres (<1%, 2/608). We were unable to determine the proportion of hypoxaemic patients who received oxygen therapy with available data. However, triangulation of existing data suggested that no facilities were equipped to meet minimum oxygen demands. We highlight the importance of a multifaceted approach to measuring oxygen access that assesses access at the point-of-care and ideally at the patient-level. We propose standard metrics to report oxygen access and describe how these can be integrated into routine health information systems and existing health facility assessment tools
Survey of 'Fusarium' species associated with crown rot of wheat and barley in eastern Australia
'Fusarium' species associated with crown rot were isolated and identified from 409 wheat, barley or durum wheat crops from the eastern Australian grain belt between 1996 and 1999. 'Fusarium pseudograminearum' was almost the only species isolated from crops inQueensland and New South Wales. 'F. pseudograminearum' was also the most common species in Victoria and South Australia, but 'F. culmorum' was frequently isolated in these states. 'F. culmorum' accounted for more than 70% of isolates from the Victorian high rainfall (>500 mm) region and the South-East region of South Australia. 'F. culmorum' comprised 18% of isolates from the Victorian medium rainfall (350-500 mm) region, and 7% of isolates from each of the Victorian low rainfall region and the Mid-North region of South Australia.'F. avenaceum', 'F. crookwellense' and 'F. graminearum' were isolated very infrequently. The proportion of 'F. culmorum' among isolates of 'Fusarium' from districts in Victoria and South Australia was strongly correlated with climatic conditions around the end of the growingseason, especially with rainfall in November
Multi-Scalar-Singlet Extension of the Standard Model - the Case for Dark Matter and an Invisible Higgs Boson
We consider a simple extension of the Standard Model by the addition of N
real scalar gauge singlets \vp that are candidates for Dark Matter. By
collecting theoretical and experimental constraints we determine the space of
allowed parameters of the model. The possibility of ameliorating the little
hierarchy problem within the multi-singlet model is discussed. The
Spergel-Steinhardt solution of the Dark Matter density cusp problem is
revisited. It is shown that fitting the recent CRESST-II data for Dark Matter
nucleus scattering implies that the standard Higgs boson decays predominantly
into pairs of Dark Matter scalars. It that case discovery of the Higgs boson at
LHC and Tevatron is impossible. The most likely mass of the dark scalars is in
the range 15 GeV \lsim \mvp \lsim 50 GeV with BR(h \to \vp\vp) up to 96%.Comment: 18 pages, 15 figure
Oligomerization of the E. coli Core RNA Polymerase: Formation of (Ī±2Ī²Ī²'Ļ)2āDNA Complexes and Regulation of the Oligomerization by Auxiliary Subunits
In this work, using multiple, dissimilar physico-chemical techniques, we demonstrate that the Escherichia coli RNA polymerase core enzyme obtained through a classic purification procedure forms stable (Ī±2Ī²Ī²'Ļ)2 complexes in the presence or absence of short DNA probes. Multiple control experiments indicate that this self-association is unlikely to be mediated by RNA polymerase-associated non-protein molecules. We show that the formation of (Ī±2Ī²Ī²'Ļ)2 complexes is subject to regulation by known RNA polymerase interactors, such as the auxiliary SWI/SNF subunit of RNA polymerase RapA, as well as NusA and Ļ70. We also demonstrate that the separation of the core RNA polymerase and RNA polymerase holoenzyme species during Mono Q chromatography is likely due to oligomerization of the core enzyme. We have analyzed the oligomeric state of the polymerase in the presence or absence of DNA, an aspect that was missing from previous studies. Importantly, our work demonstrates that RNA polymerase oligomerization is compatible with DNA binding. Through in vitro transcription and in vivo experiments (utilizing a RapAR599/Q602 mutant lacking transcription-stimulatory function), we demonstrate that the formation of tandem (Ī±2Ī²Ī²'Ļ)2āDNA complexes is likely functionally significant and beneficial for the transcriptional activity of the polymerase. Taken together, our findings suggest a novel structural aspect of the E. coli elongation complex. We hypothesize that transcription by tandem RNA polymerase complexes initiated at hypothetical bidirectional āorigins of transcriptionā may explain recurring switches of the direction of transcription in bacterial genomes
Are mice good models for human neuromuscular disease? Comparing muscle excursions in walking between mice and humans
The mouse is one of the most widely used animal models to study neuromuscular diseases and test new therapeutic strategies. However, findings from successful pre-clinical studies using mouse models frequently fail to translate to humans due to various factors. Differences in muscle function between the two species could be crucial but often have been overlooked. The purpose of this study was to evaluate and compare muscle excursions in walking between mice and humans
The burden and risks of pediatric pneumonia in Nigeria: A deskābased review of existing literature and data
Background: Pneumonia is a leading killer of children underā5 years, with a high burden in Nigeria. We aimed to quantify the regional burden and risks of pediatric pneumonia in Nigeria, and specifically the states of Lagos and Jigawa. /
Methods: We conducted a scoping literature search for studies of pneumonia morbidity and mortality in underā5 children in Nigeria from 10th December 2018 to 26th April 2019, searching: Cochrane, PubMed, and Web of Science. We included grey literature from stakeholders' websites and information shared by organizations working in Nigeria. We conducted multivariable logistic regression using the 2016 to 2017 Multiple Cluster Indicators Survey data set to explore factors associated with pneumonia. Descriptive analyses of datasets from 2010 to 2019 was done to estimate trends in mortality, morbidity, and vaccination coverage. /
Results: We identified 25 relevant papers (10 from Jigawa, 8 from Lagos, and 14 national data). None included data on pneumonia or acute respiratory tract infection burden in the health system, inpatient caseāfatality rates, severity, or ageāspecific pneumonia mortality rates at state level. Secondary data analysis found that no household or caregiver socioeconomic indicators were consistently associated with selfāreported symptoms of cough and/or difficulty breathing, and seasonality was inconsistently associated, dependant on region. /
Conclusion: There is a clear evidence gap around the burden of pediatric pneumonia in Nigeria, and challenges with the interpretation of existing household survey data. Improved survey approaches are needed to understand the risks of pediatric pneumonia in Nigeria, alongside the need for investment in reliable routine data systems to provide data on the clinical pneumonia burden in Nigeria
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