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Reports and Maps of the Geological Survey Released Only in the Open Files, 1966
There is a reference to the Espey "Some effects on urbanization on storm runoff, Waller Creek".Waller Creek Working Grou
Laboratory Bounds on Electron Lorentz Violation
Violations of Lorentz boost symmetry in the electron and photon sectors can
be constrained by studying several different high-energy phenomenon. Although
they may not lead to the strongest bounds numerically, measurements made in
terrestrial laboratories produce the most reliable results. Laboratory bounds
can be based on observations of synchrotron radiation, as well as the observed
absences of vacuum Cerenkov radiation. Using measurements of synchrotron energy
losses at LEP and the survival of TeV photons, we place new bounds on the three
electron Lorentz violation coefficients c_(TJ), at the 3 x 10^(-13) to 6 x
10^(-15) levels.Comment: 18 page
Model Atmospheres for Irradiated Stars in pre-Cataclysmic Variables
Model atmospheres have been computed for M dwarfs that are strongly
irradiated by nearby hot companions. A variety of primary and secondary
spectral types are explored in addition to models specific to four known
systems: GD 245, NN Ser, AA Dor, and UU Sge. This work demonstrates that a
dramatic temperature inversion is possible on at least one hemisphere of an
irradiated M dwarf and the emergent spectrum will be significantly different
from an isolated M dwarf or a black body flux distribution. For the first time,
synthetic spectra suitable for direct comparison to high-resolution
observations of irradiated M dwarfs in non-mass transferring post-common
envelope binaries are presented. The effects of departures from local
thermodynamic equilibrium on the Balmer line profiles are also discussed.Comment: Accepted for publication in ApJ; 12 pages, 10 figure
Sensitivity of the r-process to nuclear masses
The rapid neutron capture process (r-process) is thought to be responsible
for the creation of more than half of all elements beyond iron. The scientific
challenges to understanding the origin of the heavy elements beyond iron lie in
both the uncertainties associated with astrophysical conditions that are needed
to allow an r-process to occur and a vast lack of knowledge about the
properties of nuclei far from stability. There is great global competition to
access and measure the most exotic nuclei that existing facilities can reach,
while simultaneously building new, more powerful accelerators to make even more
exotic nuclei. This work is an attempt to determine the most crucial nuclear
masses to measure using an r-process simulation code and several mass models
(FRDM, Duflo-Zuker, and HFB-21). The most important nuclear masses to measure
are determined by the changes in the resulting r-process abundances. Nuclei
around the closed shells near N=50, 82, and 126 have the largest impact on
r-process abundances irrespective of the mass models used.Comment: 5 pages, 4 figures, accepted in European Physical Journal
Estimating the risk of adverse birth outcomes in pregnant women undergoing non-obstetric surgery using routinely collected NHS data: an observational study
Background: Previous research suggests that non-obstetric surgery is carried out in 1 – 2% of all pregnancies. However, there is limited evidence quantifying the associated risks. Furthermore, of the evidence available, none relates directly to outcomes in the UK, and there are no current NHS guidelines regarding non-obstetric surgery in pregnant women. Objectives: To estimate the risk of adverse birth outcomes of pregnancies in which non-obstetric surgery was or was not carried out. To further analyse common procedure groups. Data Source: Hospital Episode Statistics (HES) maternity data collected between 2002 – 3 and 2011 – 12. Main outcomes: Spontaneous abortion, preterm delivery, maternal death, caesarean delivery, long inpatient stay, stillbirth and low birthweight. Methods: We utilised HES, an administrative database that includes records of all patient admissions and day cases in all English NHS hospitals. We analysed HES maternity data collected between 2002 – 3 and 2011 – 12, and identified pregnancies in which non-obstetric surgery was carried out. We used logistic regression models to determine the adjusted relative risk and attributable risk of non-obstetric surgical procedures for adverse birth outcomes and the number needed to harm. Results: We identified 6,486,280 pregnancies, in 47,628 of which non-obstetric surgery was carried out. In comparison with pregnancies in which surgery was not carried out, we found that non-obstetric surgery was associated with a higher risk of adverse birth outcomes, although the attributable risk was generally low. We estimated that for every 287 pregnancies in which a surgical operation was carried out there was one additional stillbirth; for every 31 operations there was one additional preterm delivery; for every 25 operations there was one additional caesarean section; for every 50 operations there was one additional long inpatient stay; and for every 39 operations there was one additional low-birthweight baby. Limitations: We have no means of disentangling the effect of the surgery from the effect of the underlying condition itself. Many spontaneous abortions will not be associated with a hospital admission and, therefore, will not be included in our analysis. A spontaneous abortion may be more likely to be reported if it occurs during the same hospital admission as the procedure, and this could account for the associated increased risk with surgery during pregnancy. There are missing values of key data items to determine parity, gestational age, birthweight and stillbirth. Conclusions: This is the first study to report the risk of adverse birth outcomes following non-obstetric surgery during pregnancy across NHS hospitals in England. We have no means of disentangling the effect of the surgery from the effect of the underlying condition itself. Our observational study can never attribute a causal relationship between surgery and adverse birth outcomes, and we were unable to determine the risk of not undergoing surgery where surgery was clinically indicated. We have some reservations over associations of risk factors with spontaneous abortion because of potential ascertainment bias. However, we believe that our findings and, in particular, the numbers needed to harm improve on previous research, utilise a more recent and larger data set based on UK practices, and are useful reference points for any discussion of risk with prospective patients. The risk of adverse birth outcomes in pregnant women undergoing non-obstetric surgery is relatively low, confirming that surgical procedures during pregnancy are generally safe. Future work: Further evaluation of the association of non-obstetric surgery and spontaneous abortion. Evaluation of the impact of non-obstetric surgery on the newborn (e.g. neonatal intensive care unit admission, prolonged length of neonatal stay, neonatal death). Funding: The National Institute for Health Research Health Services and Delivery Research programme
Lived experiences of healthcare workers on the frontline during the COVID-19 pandemic – a qualitative interview study.
Objectives: This study aimed to investigate the presence of perceived stressors, psychological safety and teamwork in healthcare professionals. As the timeframe for this study spanned the first wave of the COVID-19 pandemic, data were captured demonstrating the impact of the pandemic on these factors. Design: Qualitative Interview Study Setting: All staff working within the Emergency and Critical Care Departments of one National Health Service Trust in London, United Kingdom. Participants: Forty-nine participants were recruited using a purposive sampling technique and interviewed when the first wave of the COVID-19 pandemic had subsided. Main Outcome Measures: Evaluation of changes in perceived stressors, psychological safety and teamwork in individuals working during the COVID-19 pandemic. Results: The thematic analysis relating to a participant’s lived experiences whilst working during COVID-19 led to the construction of 5 key themes, including ‘Psychological effects’ and ‘Changes in team dynamics’. Several psychological effects were described, including the presence of psychological distress and insights into the aetiology of moral injury. There was marked heterogeneity in participants response to COVID-19, particularly with respect to changes in team dynamics and the perception of a psychologically safe environment. Descriptions of improved team cohesiveness and camaraderie contrasted with stories of new barriers, notably due to the high workload and the impact of personal protective equipment. Building on these themes, a map of key changes arising due to the pandemic was developed, highlighting potential opportunities to provide targeted support. Conclusions: Working on the frontline of a pandemic can have significant implications for healthcare workers, putting them at risk of psychological distress and moral injury, as well as affecting team dynamics. There is striking heterogeneity in the manifestation of these challenges. Team leaders can use the themes and qualitative data from this study to help identify areas for management focus and individual and team support
Stability of Filters for the Navier-Stokes Equation
Data assimilation methodologies are designed to incorporate noisy
observations of a physical system into an underlying model in order to infer
the properties of the state of the system. Filters refer to a class of data
assimilation algorithms designed to update the estimation of the state in a
on-line fashion, as data is acquired sequentially. For linear problems subject
to Gaussian noise filtering can be performed exactly using the Kalman filter.
For nonlinear systems it can be approximated in a systematic way by particle
filters. However in high dimensions these particle filtering methods can break
down. Hence, for the large nonlinear systems arising in applications such as
weather forecasting, various ad hoc filters are used, mostly based on making
Gaussian approximations. The purpose of this work is to study the properties of
these ad hoc filters, working in the context of the 2D incompressible
Navier-Stokes equation. By working in this infinite dimensional setting we
provide an analysis which is useful for understanding high dimensional
filtering, and is robust to mesh-refinement. We describe theoretical results
showing that, in the small observational noise limit, the filters can be tuned
to accurately track the signal itself (filter stability), provided the system
is observed in a sufficiently large low dimensional space; roughly speaking
this space should be large enough to contain the unstable modes of the
linearized dynamics. Numerical results are given which illustrate the theory.
In a simplified scenario we also derive, and study numerically, a stochastic
PDE which determines filter stability in the limit of frequent observations,
subject to large observational noise. The positive results herein concerning
filter stability complement recent numerical studies which demonstrate that the
ad hoc filters perform poorly in reproducing statistical variation about the
true signal
Spin transport in ferromagnet-InSb nanowire quantum devices
Signatures of Majorana zero modes (MZMs), which are the building blocks for
fault-tolerant topological quantum computing, have been observed in
semiconductor nanowires (NW) with strong spin-orbital-interaction (SOI), such
as InSb and InAs NWs with proximity-induced superconductivity. Realizing
topological superconductivity and MZMs in this most widely-studied platform
also requires eliminating spin degeneracy, which is realized by applying a
magnetic field to induce a helical gap. However, the applied field can
adversely impact the induced superconducting state in the NWs and also places
geometric restrictions on the device, which can affect scaling of future
MZM-based quantum registers. These challenges could be circumvented by
integrating magnetic elements with the NWs. With this motivation, in this work
we report the first experimental investigation of spin transport across InSb
NWs, which are enabled by devices with ferromagnetic (FM) contacts. We observe
signatures of spin polarization and spin-dependent transport in the
quasi-one-dimensional ballistic regime. Moreover, we show that electrostatic
gating tunes the observed magnetic signal and also reveals a transport regime
where the device acts as a spin filter. These results open an avenue towards
developing MZM devices in which spin degeneracy is lifted locally, without the
need of an applied magnetic field. They also provide a path for realizing
spin-based devices that leverage spin-orbital states in quantum wires.Comment: 30 pages, 12 figure
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