1,156 research outputs found
Effect of fiber orientation on shape and stability of air-water interface on submerged superhydrophobic electrospun thin coatings
To better understand the role of fiber orientation on the stability of superhydrophobicelectrospun coatings under hydrostaticpressures, an integro-differential equation is developed from the balance of forces across the airâwater interface between the fibers. This equation is solved numerically for a series of superhydrophobicelectrospun coatings comprised of random and orthogonal fiber orientations to obtain the exact 3D shape of the airâwater interface as a function of hydrostaticpressure. More important, this information is used to predict the pressure at which the coatings start to transition from the Cassie state to the Wenzel state, i.e., the so-called critical transition pressure. Our results indicate that coatings composed of orthogonal fibers can withstand higher elevated hydrostaticpressures than those made up of randomly orientated fibers. Our results also prove that thin superhydrophobic coatings can better resist the elevated pressures. The modeling methodology presented here can be used to design nanofibrous superhydrophobic coatings for underwater applications
Continuation rates of alpha-blockers mono-therapy in adult men, prescribed by urologists or general practitioners:A pharmacy-based study
PURPOSE: α-Blockers are commonly used for the treatment of male lower urinary tract symptoms (LUTS). The Dutch GP guideline on male LUTS contains an advice to discontinue treatment after 3-6 months of successful treatment. The guideline for urologists does not support this advice. It is unclear if these differences lead to other patterns of (dis)continuation of α-blockers. We aim to study continuation rates of α-blockers, prescribed by a urologist or a general practitioner (GP), and to predict discontinuation after 1 year. METHODS: We conducted a retrospective inception cohort study on prescription patterns of α-blockers among Dutch men between 2006 and 2014, using the IADB.nl pharmacy prescription database from the University of Groningen. We selected men aged 30 years or older with a first α-blocker prescription between 2006 and 2013, and analysed continuation of prescriptions. RESULTS: The database included 12,191 individual patients with at least one α-blocker prescriptions from a urologist (44.5%) or a GP (55.5%). The median treatment period for patients who started in the GPs office was 210 days, compared to 150 days for patients with a prescription from a urologist. Of all patients, 60.3% (GP prescriptions) and 66.1% (urologists' prescriptions) had discontinued treatment (Chi-square pâ<â0.001). Discontinuation rates were age dependent with higher rates in the youngest age groups. CONCLUSION: In this study, the discontinuation rate 1 year after the initiation of treatment was high. Although Dutch GP's and urologist's guidelines differ with respect to a discontinuation advice, we could not find clinically relevant difference in (temporary) discontinuation rates
AGN Black Hole Masses and Bolometric Luminosities
Black hole mass, along with mass accretion rate, is a fundamental property of
active galactic nuclei. Black hole mass sets an approximate upper limit to AGN
energetics via the Eddington limit. We collect and compare all AGN black hole
mass estimates from the literature; these 177 masses are mostly based on the
virial assumption for the broad emission lines, with the broad-line region size
determined from either reverberation mapping or optical luminosity. We
introduce 200 additional black hole mass estimates based on properties of the
host galaxy bulges, using either the observed stellar velocity dispersion or
using the fundamental plane relation to infer ; these methods assume
that AGN hosts are normal galaxies. We compare 36 cases for which black hole
mass has been generated by different methods and find, for individual objects,
a scatter as high as a couple of orders of magnitude. The less direct the
method, the larger the discrepancy with other estimates, probably due to the
large scatter in the underlying correlations assumed. Using published fluxes,
we calculate bolometric luminosities for 234 AGNs and investigate the relation
between black hole mass and luminosity. In contrast to other studies, we find
no significant correlation of black hole mass with luminosity, other than those
induced by circular reasoning in the estimation of black hole mass. The
Eddington limit defines an approximate upper envelope to the distribution of
luminosities, but the lower envelope depends entirely on the sample of AGN
included. For any given black hole mass, there is a range in Eddington ratio of
up to three orders of magnitude.Comment: 43 pages with 10 figures. Accepted for publication in Ap
Separation between coherent and turbulent fluctuations. What can we learn from the Empirical Mode Decomposition?
The performances of a new data processing technique, namely the Empirical
Mode Decomposition, are evaluated on a fully developed turbulent velocity
signal perturbed by a numerical forcing which mimics a long-period flapping.
First, we introduce a "resemblance" criterion to discriminate between the
polluted and the unpolluted modes extracted from the perturbed velocity signal
by means of the Empirical Mode Decomposition algorithm. A rejection procedure,
playing, somehow, the role of a high-pass filter, is then designed in order to
infer the original velocity signal from the perturbed one. The quality of this
recovering procedure is extensively evaluated in the case of a "mono-component"
perturbation (sine wave) by varying both the amplitude and the frequency of the
perturbation. An excellent agreement between the recovered and the reference
velocity signals is found, even though some discrepancies are observed when the
perturbation frequency overlaps the frequency range corresponding to the
energy-containing eddies as emphasized by both the energy spectrum and the
structure functions. Finally, our recovering procedure is successfully
performed on a time-dependent perturbation (linear chirp) covering a broad
range of frequencies.Comment: 23 pages, 13 figures, submitted to Experiments in Fluid
Time to onset in statistical signal detection revisited:A follow-up study in long-term onset adverse drug reactions
PURPOSE: In a previous study, we developed a signal detection method using the time to onset (TTO) of adverse drug reactions (ADRs). The aim of the current study was to investigate this method in a subset of ADRs with a longer TTO and to compare its performance with disproportionality analysis. METHODS: Using The Netherlands's spontaneous reporting database, TTO distributions for drug-ADR associations with a median TTO of 7 days or more were compared with other drugs with the same ADR using the two-sample Anderson-Darling (AD) test. Presence in the Summary of Product Characteristics (SPC) was used as the gold standard for identification of a true ADR. Twelve combinations with different values for the number of reports and median TTO were tested. Performance in terms of sensitivity and positive predictive value (PPV) was compared with disproportionality analysis. A sensitivity analysis was performed to compare the results with those from the previous study. RESULTS: A total of 38 017 case reports, containing 32 478 unique drug-ADR associations. Sensitivity was lower for the TTO method (range 0.08-0.34) compared with disproportionality analysis (range 0.60-0.87), whereas PPV was similar for both methods (range 0.93-1.0). The results from the sensitivity analysis were similar to the original analysis. CONCLUSIONS: Because of its low sensitivity, the developed TTO method cannot replace disproportionality analysis as a signal detection tool. It may be useful in combination with other methods
Soliton Induced Singularities in 2 d Gravity and their Evaporation
Positive energy singularities induced by Sine-Gordon solitons in 1+1
dimensional dilaton gravity with positive and negative cosmological constant
are considered. When the cosmological constant is positive, the singularities
combine a white hole, a timelike singularity and a black hole joined smoothly
near the soliton center. When the cosmological constant is negative, the
solutions describe two timelike singularities joined smoothly near the soliton
center. We describe these spacetimes and examine their evaporation in the one
loop approximation.Comment: 15 pages (37.7 kb), PHYZZX. Figures available from authors
Sequential group trial to determine gastrointestinal site of absorption and systemic exposure of azathioprine
Azathioprine (AZA) is used in the treatment of patients with refractory inflammatory bowel disease; however, its use is limited because of systemic toxicity associated with long-term use. Ileocecal delivery of AZA might be advantageous if local intestinal therapeutic effects could be provided with decreased systemic side effects. Decreased cecal systemic absorption would allow higher dosages of AZA to be administered. A two-phase study was performed to compare the systemic exposure of AZA and 6-mercaptopurine (6-MP) following administration of AZA into the stomach, jejunum, and cecum and to compare the systemic exposure to AZA and 6-MP following administration of three different dosages of AZA into the cecum. In phase I, six healthy male volunteers received three 50 mg sequential doses of AZA via an oral tube directly placed into the stomach, jejunum, and cecum, respectively. In phase II, six healthy male volunteers received three different dosages (50, 300, 600 mg of AZA) into the cecum. Plasma concentrations of AZA and 6-MP at various times were quantified and area under the plasma concentration-time curve (AUC) and mean residence time (MRT) were determined. No significant differences in the AUC of AZA were seen at the different sites. The AUC of 6-MP following administration of AZA into the jejunum (67.0 ± 30.1 ng à hr/ml) was higher compared to the stomach (39.9 ± 38.1 ng/hr/ml) and cecum (29.2 ± 10.9 ng à hr/ml). Jejunal absorption was 68% higher than absorption from the stomach and 129% higher than that of the cecum. Gastric absorption was 27% higher than that of the cecum. Increased dosages given into the cecum resulted in increased AUCs of AZA and 6-MP. The AUCs of AZA following 50, 300, and 600 mg dosages were 16.9 ± 7.4, 52.3 ± 67.2, and 132 ± 151 ng à hr/ml, respectively, and the AUCs of 6-MP were 22.2 ± 14.9, 63.4 ± 50.6, and 104 ± 115 ng à hr/ml, respectively. Systemic exposure to 6-MP is reduced following administration of AZA into the cecum, most likely secondary to reduced absorption of 6-MP from the colon. Higher dosages of AZA presented to the cecum do result in increased systemic absorption, but may still allow more drug to be administered with less toxicity than the same dose received orally
Testing intermediate-age stellar evolution models with VLT photometry of LMC clusters. I. The data
This is the first of a series of three papers devoted to the calibration of a
few parameters of crucial importance in the modeling of the evolution of
intermediate-mass stars, with special attention to the amount of convective
core overshoot. To this end we acquired deep V and R photometry for three
globular clusters of the Large Magellanic Cloud (LMC), namely NGC 2173, SL 556
and NGC 2155, in the age interval 1-3 Gyr. In this first paper, we describe the
aim of the project, the VLT observations and data reduction, and we make
preliminary comparisons of the color-magnitude diagrams with both Padova and
Yonsei-Yale isochrones. Two following papers in this series present the results
of a detailed analysis of these data, independently carried out by members of
the Yale and Padova stellar evolution groups. This allows us to compare both
sets of models and discuss their main differences, as well as the systematic
effects that they would have to the determination of the ages and metallicities
of intermediate-age single stellar populations.Comment: 27 pages with 10 figures. Accepted by the Astronomical Journa
Small-cell lung cancer patients are just âa little bitâ tired: response shift and self-presentation in the measurement of fatigue
Background: Response shift has gained increasing attention in the measurement of health-related quality of life (QoL) as it may explain counter-intuitive findings as a result of adaptation to deteriorating health. Objective: To search for response shift type explanations to account for counter-intuitive findings in QoL measurement. Methods: Qualitative investigation of the response behaviour of small-cell lung cancer (SCLC) patients (n = 23) in the measurement of fatigue with The European Organization for Research and Treatment of Cancer Core Quality of Life Questionnaire (EORTC QLQ-C30) question 'were you tired'. Interviews were conducted at four points during 1st line chemotherapy: at the start of chemotherapy, 4 weeks later, at the end of chemotherapy, and 6 weeks later. Patients were asked to 'think aloud' when filling in the questionnaire. Results: Fifteen patients showed discrepancies between their answer to the EORTC question 'were you tired' and their level of fatigue spontaneously reported during the interview. These patients chose the response options 'not at all' or 'a little' and explained their answers in various ways. In patients with and without discrepancies, we found indications of recalibration response shift (e.g. using a different comparison standard over time) and of change in perspective (e.g. change towards a more optimistic perspective). Patients in the discrepancy group reported spontaneously how they dealt with diagnosis and treatment, i.e. by adopting protective and assertive behaviour and by fighting the stigma. They distanced themselves from the image of the stereotypical cancer patient and presented themselves as not suffering and accepting fatigue as consequence of treatment. Conclusion: In addition to response shift, this study suggests that 'self-presentation' might be an important mechanism affecting QoL measurement, particularly during phases when a new equilibrium needs to be found
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