236 research outputs found
Dealing with Interval Scale Data in Data Envelopment Analysis
This papaer considers the problem of interval scale data in the most widely used models of Data Envelopment Analysis (DEA), the CCR, and the BCC models. Radial models require inputs and outputs measured on the ratio scale. Our focus is on how to deal with interval scale variables especially when the interval scale variable is a difference of two ratio scale variables like profit or the decrease/increase in bank accounts. Using these ratio scale variables as variables in the DEA model we suggest radial models. An approach to how to deal with interval scale variables when we relax the radiality assumption is also discussed
Evolutionary multi-stage financial scenario tree generation
Multi-stage financial decision optimization under uncertainty depends on a
careful numerical approximation of the underlying stochastic process, which
describes the future returns of the selected assets or asset categories.
Various approaches towards an optimal generation of discrete-time,
discrete-state approximations (represented as scenario trees) have been
suggested in the literature. In this paper, a new evolutionary algorithm to
create scenario trees for multi-stage financial optimization models will be
presented. Numerical results and implementation details conclude the paper
Lyman- polarization from cosmological ionization fronts: II. Implications for intensity mapping
This is the second paper in a series whose aim is to predict the power
spectrum of intensity and polarized intensity from cosmic reionization fronts.
After building the analytic models for intensity and polarized intensity
calculations in paper I, here we apply these models to simulations of
reionization. We construct a geometric model for identifying front boundaries,
calculate the intensity and polarized intensity for each front, and compute a
power spectrum of these results. This method was applied to different
simulation sizes and resolutions, so we ensure that our results are convergent.
We find that the power spectrum of fluctuations at in a bin of width
() is is erg s cm
sr for the intensity , erg s cm
sr for the -mode polarization, and erg s
cm sr for the -mode polarization at .
After computing the power spectrum, we compare results to detectable scales and
discuss implications for observing this signal based on a proposed experiment.
We find that, while fundamental physics does not exclude this kind of mapping
from being attainable, an experiment would need to be highly ambitious and
require significant advances to make mapping Lyman- polarization from
cosmic reionization fronts a feasible goal.Comment: 18 pages, 9 figures, to be submitted to JCA
Lyman-{\alpha} polarization from cosmological ionization fronts: I. Radiative transfer simulations
In this paper, we present the formalism of simulating Lyman- emission
and polarization around reionization ( = 8) from a plane-parallel ionization
front. We accomplish this by using a Monte Carlo method to simulate the
production of a Lyman- photon, its propagation through an ionization
front, and the eventual escape of this photon. This paper focuses on the
relation of the input parameters of ionization front speed , blackbody
temperature , and neutral hydrogen density , on
intensity and polarized intensity as seen by a distant observer. The
resulting values of intensity range from
erg/cm/s/sr to erg/cm/s/sr , and the
polarized intensity ranges from erg/cm/s/sr to
erg/cm/s/sr. We found that higher ,
higher , and higher contribute to higher intensity, as well as
polarized intensity, though the strongest dependence was on the hydrogen
density. The dependence of viewing angle of the front is also explored. We
present tests to support the validity model, which makes the model suitable for
further use in a following paper where we will calculate the intensity and
polarized intensity power spectrum on a full reionization simulation.Comment: 29 pages, 13 figures, to be submitted to JCA
Corrections to Hawking radiation from asteroid-mass primordial black holes: description of the stochastic charge effect in quantum electrodynamics
Hawking radiation sets stringent constraints on Primordial Black Holes (PBHs)
as a dark matter candidate in the regime based on
the evaporation products such as photons, electrons, and positrons. This
motivates the need for rigorous modeling of the Hawking emission spectrum.
Using semi-classical arguments, Page [Phys. Rev. D 16, 2402 (1977)] showed that
the emission of electrons and positrons is altered due to the black hole
acquiring an equal and opposite charge to the emitted particle. The Poisson
fluctuations of emitted particles cause the charge to random walk, but
since acquisition of charge increases the probability of the black hole
emitting another charged particle of the same sign, the walk is biased toward
, and approaches an equilibrium probability distribution with
finite variance . This paper explores how this ``stochastic
charge'' phenomenon arises from quantum electrodynamics (QED) on a
Schwarzschild spacetime. We prove that (except for a small Fermi blocking term)
the semi-classical variance agrees with the variance of a
quantum operator , where may be
thought of as an ``atomic number'' that includes the black hole as well as
charge near it (weighted by a factor of ). In QED, the fluctuations in
do not arise from the black hole itself (whose charge remains
fixed), but rather as a collective effect in the Hawking-emitted particles
mediated by the long-range electromagnetic interaction. We find the rms charge
asymptotes to 3.44 at small PBH masses g, declining to 2.42 at g.Comment: 36 pages, 3 figure
Structural characterization of EGFR exon 19 deletion mutation using molecular dynamics simulation
Epidermal growth factor receptor (EGFR) is a tyrosine kinase receptor
important in diverse biological processes including cell proliferation
and survival. Upregulation of EGFR activity due to over-expression or
mutation is widely implicated in cancer. Activating somatic mutations of
the EGFR kinase are postulated to affect the conformation and/or
stability of the protein, shifting the EGFR inactive-active state
equilibrium towards the activated state. Here, we examined a common EGFR
deletion mutation, Δ746ELREA750, which is
frequently observed in non-small cell lung cancer patients. By using
molecular dynamics simulation, we investigated the structural effects of
the mutation that lead to the experimentally reported increases in
kinase activity. Simulations of the active form wild-type and ΔELREA
EGFRs revealed the deletion stabilizes the αC helix of the kinase
domain, which is located adjacent to the deletion site, by rigidifying
the flexible β3-αC loop that accommodates the ELREA sequence.
Consequently, the αC helix is stabilized in the “αC-in” active
conformation that would prolong the time of the activated state.
Moreover, in the mutant kinase, a salt bridge between E762 and K745,
which is key for EGFR activity, was also stabilized during the
simulation. Additionally, the interaction between EGFR and ATP was
favored by ΔELREA EGFR over wild-type EGFR, as reflected by the number
of hydrogen bonds formed and the free energy of binding. Simulation of
inactive EGFR suggested the deletion would promote a shift from the
inactive conformation towards active EGFR, which is supported by the
inward movement of the αC helix. The MDS results also align with the
effects of tyrosine kinase inhibitors on ΔELREA and wild-type EGFR lung
cancer cell lines, where more pronounced inhibition was observed against
ΔELREA than for wild-type EGFR by inhibitors recognizing the active
kinase conformation.</p
Polyneuropathy monitoring in Parkinson's disease patients treated with levodopa/carbidopa intestinal gel
Objectives Levodopa-carbidopa-intestinal-gel (LCIG) infusion is an effective treatment for advanced PD with motor fluctuations. Polyneuropathy occurs as a complication in 10-15% of patients. We wanted to assess the frequency of polyneuropathy in Finnish advanced Parkinson's disease (PD) patients with continuous LCIG infusion, and the value of different clinical monitoring parameters during follow-up. Materials and methods Patient records of PD patients started on LCIG infusion at Helsinki University Hospital who received nerve conduction studies at baseline and 6 months after treatment initiation were reviewed for epidemiological information, mini mental state examination, baseline and 6 months' UPRDS-III, weight, body mass index, levodopa dose (LD), plasma homocysteine levels, folate, vitamin B6 and B12. Results Out of 19 patients (n = 6 on B-vitamin substitution), two (10.5%) developed new-onset polyneuropathy after initiation of LCIG therapy (n = 0 with vitamin substitution). Neuropathy was associated with significant weight loss (BMI reduction > 1.5), but not with other monitoring parameters. Homocysteine rose significantly in patients not substituted with B-vitamin complex, but not in patients with B-vitamin substitution. Homocysteine changes correlated with LD changes in the absence of vitamin B substitution. After oral B-vitamin substitution, both patients' polyneuropathy remained electrophysiologically and clinically stable. Conclusions Rates of polyneuropathy in Finnish PD patients with LCIG treatment are comparable to previous studies. Patients' weight should be included in regular follow up monitoring and can be used for patient self-monitoring. Vitamin B substitution appears to reduce coupling between levodopa dose and homocysteine and may be useful to prevent polyneuropathy related to LCIG.Peer reviewe
Modular literature review: a novel systematic search and review method to support priority setting in health policy and practice
Adalimumab and sulfasalazine in alleviating sacroiliac and aortic inflammation detected in PET/CT in patients with axial spondyloarthritis : PETSPA
Publisher Copyright: © 2021 The Authors. Immunity, Inflammation and Disease published by John Wiley & Sons Ltd.Aim: Inflammatory signals in the sacroiliac (SI) joints and the aorta of patients with axial spondyloarthritis (axSpA) were graded by positron emission tomography/computed tomography (PET/CT) imaging before and after treatment with sulfasalazine (SSZ) or adalimumab (ADA). Methods: Patients with axSpA, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) ≥ 4, were recruited. Disease-modifying antirheumatic drug-naïve patients started SSZ for 12 weeks, whereas those with prestudy treatment with or contraindication to SSZ commenced ADA for 16 weeks. In addition, those patients in the SSZ group with insufficient response commenced ADA for 16 weeks. 18F-fluorodeoxyglucose PET/CT was performed after inclusion and after treatment with SSZ and ADA. Maximum standardized uptake value (SUVmax) was assessed for the aorta and the SI joints, and maximal target-to-blood-pool ratio (TBRmax) only for the aorta. Results: Among five SSZ patients, mean ± SD BASDAI was 4.7 ± 1.6 before and 3.5 ± 1.4 after treatment (p =.101). In 13 ADA patients, the BASDAI decreased from 5.4 ± 1.6 to 2.8 ± 2.2 (p <.001). Among the SSZ patients, SUVmax in SI joints decreased from 2.35 ± 0.55 to 1.51 ± 0.22 (−35.8%, p =.029). Aortic TBRmax decreased from 1.59 ± 0.43 to 1.26 ± 0.26 (−33.2%, p =.087). In the ADA patients, SUVmax in the SI joints was 1.92 ± 0.65 before and 1.88 ± 0.54 after treatment (−1.8%, p =.808) and TBRmax in the aorta 1.50 ± 0.60 before and 1.40 ± 0.26 after treatment (−6.7%, p =.485). Conclusions: Our small open-label study showed that SSZ may reduce PET-CT-detectable inflammation in the SI joints, with a trend towards a reduction in the aorta.Peer reviewe
Evaluation of Circulating Cardiovascular Biomarker Levels for Early Detection of Congenital Heart Disease in Newborns in Sweden
Congenital heart disease (CHD) is the most common congenital malformation in humans worldwide. Circulating cardiovascular biomarkers could potentially improve the early detection of CHD, even in asymptomatic newborns.\nTo assess the performance of a dried blood spot (DBS) test to measure the cardiovascular biomarker amino terminal fragment of the prohormone brain-type natriuretic peptide (NT-proBNP) levels in newborns and to compare DBS with standard EDTA analysis in control newborns during the first week of life.\nThis diagnostic study was conducted in a single regional pediatric service in southern Sweden. Healthy, term neonates born between July 1, 2018, and May 31, 2019, were prospectively enrolled and compared against retrospectively identified newborns with CHD born between September 1, 2003, and September 30, 2019. Neonates who required inpatient treatment beyond the standard postnatal care were excluded.\nNew DBS test for NT-proBNP quantification in newborns that used 3 μL of blood vs the current screening standard.\nPerformance of the new test and when combined with pulse oximetry screening was measured by receiver operating characteristic curve analysis. Performance of the new test and EDTA screening was compared using Pearson linear correlation analysis.\nThe DBS samples of 115 neonates (81 control newborns and 34 newborns with CHD, of whom 63 were boys [55%] and the mean [SD] gestational age was 39.6 [1.4] weeks) were analyzed. The new NT-proBNP test alone identified 71% (n = 24 of 34) of all CHD cases and 68% (n = 13 of 19) of critical CHD cases as soon as 2 days after birth. Detection of any CHD type improved to 82% (n = 28 of 34 newborns) and detection of critical CHD improved to 89% (n = 17 of 19 newborns) when combined pulse oximetry screening and NT-proBNP test results were used. Performance of the NT-proBNP test was excellent when control newborns were matched to newborns with CHD born between July 1, 2018, and May 31, 2019 (area under the curve, 0.96; SE, 0.027; 95% CI, 0.908-1.0; asymptotic P < .05).\nThis study found that NT-proBNP assay using minimal DBS samples appears to be timely and accurate in detecting CHD in newborns and to discriminate well between healthy newborns and newborns with various types of CHD. This finding warrants further studies in larger cohorts and highlights the potential of NT-proBNP to improve neonatal CHD screening.\nImportance\nObjectives\nDesign, Setting, and Participants\nExposure\nMain Outcomes and Measures\nResults\nConclusions and Relevanc
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