1,366 research outputs found
Absence of Dipole Transitions in Vortices of Type II Superconductors
The response of a single vortex to a time dependent field is examined
microscopically and an equation of motion for vortex motion at non-zero
frequencies is derived. Of interest are frequencies near ,
where is the bulk energy gap and is the fermi energy. The low
temperature, clean, extreme type II limit and maintaining of equilibrium with
the lattice are assumed. A simplification occurs for large planar mass
anisotropy. Thus the results may be pertinent to materials such as and
high temperature superconductors. The expected dipole transition between core
states is hidden because of the self consistent nature of the vortex potential.
Instead the vortex itself moves and has a resonance at the frequency of the
transition.Comment: 12 pages, no figure
Thomae type formulae for singular Z_N curves
We give an elementary and rigorous proof of the Thomae type formula for
singular curves. To derive the Thomae formula we use the traditional
variational method which goes back to Riemann, Thomae and Fuchs.Comment: 22 page
Multi-scale analysis of compressible viscous and rotating fluids
We study a singular limit for the compressible Navier-Stokes system when the
Mach and Rossby numbers are proportional to certain powers of a small parameter
\ep. If the Rossby number dominates the Mach number, the limit problem is
represented by the 2-D incompressible Navier-Stokes system describing the
horizontal motion of vertical averages of the velocity field. If they are of
the same order then the limit problem turns out to be a linear, 2-D equation
with a unique radially symmetric solution. The effect of the centrifugal force
is taken into account
G(2) quivers
We present, in explicit matrix representation and a modernity befitting the community, the classification of the finite discrete subgroups of G2 and compute the McKay quivers arising therefrom. Of physical interest are the classes of Script N = 1 gauge theories descending from M-theory and of mathematical interest are possible steps toward a systematic study of crepant resolutions to smooth G2 manifolds as well as generalised McKay Correspondences. This writing is a companion monograph to hep-th/9811183 and hep-th/9905212, wherein the analogues for Calabi-Yau three- and four-folds were considered
Non-adherence to antimicrobial guidelines in patients with bloodstream infection visiting the emergency department
_Objective:_ Non-adherence to antimicrobial guidelines in patients with bloodstream infection can result in undertreatment, overtreatment, or equivalent treatment, and could lead to suboptimal care. Our aim was to examine the association between non-adherence and appropriate coverage as well as to assess the impact of non-adherence on 30-day mortality.
_Methods:_ We conducted a retrospective cohort study between 2012 and 2017 at a tertiary university hospital. Adult patients attending the emergency department with a bloodstream infection were included. Adherence was defined as guideline-recommended antibiotic therapy. Non-adherence was either undertreatment (too narrow-spectrum), overtreatment (too broad-spectrum), or equivalent treatment. Outcomes were appropriate coverage (i.e. antibiotic therapy that matches in vitro susceptibility of the isolated bacteria) and 30-day mortality.
_Results:_ We included 909 patients of whom 395 (43.5%) were treated adherently, 355 (39.1%) were undertreated, 87 (9.6%) were overtreated, and 72 (7.9%) received an equivalent treatment. Overtreated patients were more severely ill, whilst undertreated patients had more favorable patient characteristics. Overtreatment did not result in higher appropriate coverage, whereas undertreatment was associated with lower coverage (OR[95%CI]: 0.18 [0.12; 0.26]). Overtreatment and undertreatment were not associated with 30-day mortality.
_Conclusions:_ Guideline adherence likely depends on disease severity, because overtreatment was more often observed in patients with high disease severity and undertreatment in less severely ill patients. Undertreatment was associated lower appropriate coverage but not with higher mortality. However, this can be the result of residual confounding. Overtreatment did not result in higher appropriate antibiotic coverage nor a survival benefit. Therefore, overtreatment seems not justifiable
Programmed electrical stimulation-guided encircling cryoablation concomitant to surgical ventricular reconstruction for primary prevention of ventricular arrhythmias
Diabetes mellitus: pathophysiological changes and therap
Quadriceps volumes are reduced in people with patellofemoral joint osteoarthritis
Objectives: This study aimed to (1) compare the volumes of vastus medialis (VM), vastus lateralis (VL), vastus intermedius and rectus femoris and the ratio of VM/VL volumes between asymptomatic controls and patellofemoral joint osteoarthritis (PFJ OA) participants; and (2) assess the relationships between cross-sectional area (CSA) and volumes of the VM and VL in individuals with and without PFJ OA. Methods: Twenty-two participants with PFJ OA and 11 controls aged ≥40 years were recruited from the community and practitioner referrals. Muscle volumes of individual quadriceps components were measured from thigh magnetic resonance (MR) images. The CSA of the VM and lateralis were measured at 10 equally distributed levels (femoral condyles to lesser femoral trochanter). Results: PFJ OA individuals had smaller normalized VM (mean difference 0.90 cm ·kg , α = 0.011), VL (1.50 cm ·kg , α = 0.012) and rectus femoris (0.71 cm ·kg , α = 0.009) volumes than controls. No differences in the VM/VL ratio were observed. The CSA at the third level (controls) and fourth level (PFJ OA) above the femoral condyles best predicted VM volume, whereas the VL volume was best predicted by the CSA at the seventh level (controls) and sixth level (PFJ OA) above the femoral condyles. Conclusion: Reduced quadriceps muscle volume was a feature of PFJ OA. Muscle volume could be predicted from CSA measurements at specific levels in PFJ OA patients and controls
Predicting 30-day mortality using point-of-care testing; an external validation and derivation study
Background
Early risk stratification for guiding treatment priority in the emergency department (ED) is
becoming increasingly important. Existing prediction models typically use demographics,
vital signs and laboratory parameters. Laboratory-based models require blood testing,
which may cause substantial delay. However, these delays can be prevented by the use of
point-of-care testing (POCT), where results are readily available. We aimed to externally
validate a laboratory-based model for mortality and subsequently assessed whether a
POCT model yields comparable performance.
Methods
All adult patients visiting the ED of a university hospital between January 1st, 2012 and
December 31st, 2016 were retrospectively reviewed for inclusion. Primary outcome was
defined as 30-day mortality after ED presentation. We externally validated one existing prediction model including age, glucose, urea, sodium, haemoglobin, platelet count and white
blood cell count. We assessed the predictive performance by discrimination, expressed as
Area under the Curve (AUC). We compared the existing model to an equivalent model using
predictors that are available with POCT (i.e. glucose, urea, sodium and haemoglobin). Additionally, we internally validated these models with bootstrapping.
Results
We included 34,437 patients of whom 1,942 (5.6%) died within 30 days. The AUC of the laboratory-based model was 0.794. We refitted this model to our ED population and found an
AUC of 0.812, which decreased only slightly to 0.790 with only POCT parameters.
Conclusions
Our POCT-model performs similar to existing laboratory-based models in identifying
patients at high risk for mortality, with results available within minutes. Although the model needs further validation and evaluation, it shows the potential of POCT for early risk stratification in the ED
Predicting mortality in patients with suspected sepsis at the Emergency Department; A retrospective cohort study comparing qSOFA, SIRS and National Early Warning Score
Objective
In hospitalized patients, the risk of sepsis-related mortality can be assessed using the quick
Sepsis-related Organ Failure Assessment (qSOFA). Currently, different tools that predict
deterioration such as the National Early Warning Score (NEWS) have been introduced in
clinical practice in Emergency Departments (ED) worldwide. It remains ambiguous which
screening tool for mortality at the ED is best. The objective of this study was to evaluate the
predictive performance for mortality of two sepsis-based scores (i.e. qSOFA and Systemic
Inflammatory Response Syndrome (SIRS)-criteria) compared to the more general NEWS
score, in patients with suspected infection directly at presentation to the ED.
Methods
We performed a retrospective cohort study. Patients who presented to the ED between
June 2012 and May 2016 with suspected sepsis in a large tertiary care center were included.
Suspected sepsis was defined as initiation of intravenous antibiotics and/or collection of any
culture in the ED. Outcome was defined as 10-day and 30-day mortality after ED presentation. Predictive performance was expressed as discrimination (AUC) and calibration using
Hosmer-Lemeshow goodness-of-fit test. Subsequently, sensitivity, and specificity were
calculated.
Results
In total 8,204 patients were included of whom 286 (3.5%) died within ten days and 490
(6.0%) within 30 days after presentation. NEWS had the best performance, followed by qSOFA and SIRS (10-day AUC: 0.837, 0.744, 0.646, 30-day AUC: 0.779, 0.697, 0.631).
qSOFA (�2) lacked a high sensitivity versus SIRS (�2) and NEWS (�7) (28.5%, 77.2%,
68.0%), whilst entailing highest specificity versus NEWS and SIRS (93.7%, 66.5%, 37.6%).
Conclusions
NEWS is more accurate in predicting 10- and 30-day mortality than qSOFA and SIRS in
patients presenting to the ED with suspected sepsis
On the relative positions of the peaks in Raman and tunneling spectra of d-wave superconductors
We study Raman intensity and the density of states
in isotropic 2D d-wave superconductors. For an ideal gas,
and have sharp peaks at and , respectively, where is the maximum value of the gap.
We study how the peak positions are affected by the fermionic damping due to
impurity scattering.
We show that while the damping generally shifts the peak positions to larger
frequencies, the peak in still occurs at almost twice the peak
position in and therefore cannot account for the experimentally
observed downturn shift of the peak frequency in in underdoped
cuprates compared to twice that in . We also discuss how the
fermionic damping affects the dynamical spin susceptibility.Comment: 5 pages, 2 figure
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