DC lifetime of encapsulated organic light emitting diodes

Organic light emitting diodes (OLEDs) are ideal sources for chemical and biological optical sensors, due to their simplicity, low cost (disposable applications) and possibility to be integrated on chip and fabricated in the form of large 2D arrays (microarray fluorescence) even on flexible plastic substrates. OLEDs with lifetimes of a few hundreds of hours at initial luminance values in the range (500\uf71000) cd/m 2 are suitable for the above applications, but these lifetimes can be achieved only by a proper encapsulation. Fast, simple and inexpensive encapsulation methods are highly desirable to keep the low cost profile and for this reasonwe report two different encapsulation structures and compare their effectiveness in increasing device lifetime of bilayer green emitting OLEDs based on Tris (8 idroxyquinoline) aluminum(Alq3) as emitting material

Model Reduction of a Piecewise Linear Flexible Mechanical Oscillator

We study the reduced order modeling of a nonlinear flexible oscillator in which a Bernoulli-Euler beam with a permanent tip magnet is subjected to a position-triggered electromagnetic kick force. This results in non-smooth boundary conditions capable of exciting many degrees of freedom. The system is modeled as piecewise linear with the different boundary conditions determining different regions of a hybrid phase space. With kick strength as parameter, its bifurcation diagram is found to exhibit a range of periodic and chaotic behaviors. Proper orthogonal decomposition (POD) is used to estimate the system's intrinsic dimensionality. However, conventional POD's purely statistical analysis of spatial covariance does not guarantee accuracy of reduced order models (ROMs). We therefore augment POD by employing a previously-developed energy closure criterion that selects ROM dimension by ensuring approximate energy balance on the reduced subspace. This physics-based criterion yields accurate ROMs with 8 degrees of freedom. Remarkably, we show that ROMs formulated at particular values of the kick strength can nevertheless reconstruct the entire bifurcation structure of the original system. Our results demonstrate that energy closure analysis outperforms variance-based estimates of effective dimension for nonlinear structural systems, and is capable of providing ROMs that are robust even across stability transitions.Comment: 30 pages, 9 figure

Patients without colonoscopic follow-up after abnormal fecal immunochemical tests are often unaware of the abnormal result and report several barriers to colonoscopy.

BackgroundThe fecal immunochemical test (FIT) is the second most commonly used colorectal cancer (CRC) screening modality in the United States; yet, follow-up of abnormal FIT results with diagnostic colonoscopy is underutilized. Our objective was to determine patient-reported barriers to diagnostic colonoscopy following abnormal FIT in an academic healthcare setting.MethodsWe included patients age 50-75 with an abnormal FIT result between 1/1/2015 and 10/31/2017 and no documented follow-up diagnostic colonoscopy. We abstracted demographic data from the electronic health record (EHR). Study personnel conducted telephone surveys with patients to confirm colonoscopy completion and elicit data on notification of FIT results and barriers to colonoscopy. We also provided brief verbal education about diagnostic colonoscopy. We calculated frequencies of demographic data and survey responses and compared survey responses by interest in colonoscopy after education.ResultsWe surveyed 67 patients. Fifty-one were aware of the abnormal FIT result, and a majority learned of the abnormal FIT result by direct communication with providers (19, 37.3%) or EHR messaging (11, 21.6%). Overall, fifty-three patients (79.1%) confirmed lack of colonoscopy, citing provider-related (19, 35.8%), patient-related (16, 30.2%), system-related (1, 1.9%), or multifactorial (17, 32.1%) reasons. Lack of knowledge of FIT result (14, 26.4%) was most common. After brief education, 20 (37.7%) patients requested colonoscopy.ConclusionPatients with an abnormal FIT reported various multi-level barriers to diagnostic colonoscopy after abnormal FIT, including knowledge of FIT results. When provided with brief education, participants expressed interest in diagnostic colonoscopy. Future efforts will evaluate interventions to improve colonoscopy follow-up

Heavily obscured AGN in the local Universe

We present here a new powerful diagnostic plot to select heavily obscured AGN in the local universe by combining infrared (Spitzer, IRAS) and X-ray (XMM) information. On the basis of this plot, we selected a sample of X-ray obscured sources in the 2XMM catalogue and found seven newly discovered Compton-thick AGN candidates.Comment: 2 pages, 2 figures, To appear in refereed Proceedings of "X-ray Astronomy 2009: Present Status, Multi-Wavelength Approach and Future Perspectives", Bologna, Italy, September 7-11, 2009, AIP, eds. A. Comastri, M. Cappi, and L. Angelin

The Swift-BAT survey reveals the orbital period of three high-mass X-ray binaries

A growing number of previously hidden Galactic X-ray sources are now detected with recent surveys performed by the Integral and Swift satellites. Most of these new sources eluded past surveys due to their large local X-ray extinction and consequent low soft X-ray flux. The Swift-BAT performs daily monitoring of the sky in an energy band (15-150 keV) which is only marginally affected by X-ray extinction, thus allowing for the search of long periodicities in the light curve and identification of the nature of the X-ray sources. We performed a period search using the folding technique in the Swift-BAT light curves of three Integral sources: IGR J05007-7047, IGR J13186-6257 and IGR J17354-3255. Their periodograms show significant peaks at 30.77$\pm$0.01 d, 19.994$\pm$0.01 d and 8.448$\pm$0.002 d, respectively. We estimate the significance of these features from the chi squared distribution of all the trials, finding a probability less than 1.5$\times10^{-4}$ that the detections occurred due to chance. We complement our analysis with the study of their broadband X-ray emission. We identify the periodicities with the orbital periods of the sources. The periods are typical for the wind accretors X-ray binaries and we support this identification showing that also their energy spectra are compatible with an X-ray spectral emission characteristic of high-mass X-ray binaries. The spectrum of IGR J05007-704 that resides in the Large Magellanic Cloud, does not show any intrinsic local absorption, whereas the spectra of the Galactic sources IGR J17354-3255 and IGR J13186-6257 may be affected by a local absorber. The folded light curve for IGR J13186-6257 suggests a possible Be companion star.Comment: 10 pages, 14 figures. Accepted for publication in A&

The Palermo Swift-BAT hard X-ray catalogue III. Results after 54 months of sky survey

We present the Second Palermo Swift-BAT hard X-ray catalogue obtained by analysing data acquired in the first 54 months of the Swift mission. Using our software dedicated to the analysis of data from coded mask telescopes, we analysed the BAT survey data in three energy bands (15-30 keV, 15-70 keV, 15-150 keV), obtaining a list of 1256 detections above a significance threshold of 4.8 standard deviations. The identification of the source counterparts is pursued using two strategies: the analysis of field observations of soft X-ray instruments and cross-correlation of our catalogue with source databases.The survey covers 50% of the sky to a 15--150 keV flux limit of 1.0 x 10^-11 erg s^-1 cm^-2 and 9.2 x 10^-12 erg s^-1 cm^-2 for |b| 10 degrees, respectively. The Second Palermo Swift-BAT hard X-ray catalogue includes 1079 (86%) hard X-ray sources with an associated counterpart (26 with a double association and 2 with a triple association) and 177 BAT excesses (14%) that still lack a counterpart. The distribution of the BAT sources among the different object classes consists of 19% Galactic sources, 57% extragalactic sources, and 10% sources with a counterpart at softer energies whose nature has not yet been determined. About half of the BAT associated sources lack a counterpart in the ROSAT catalogues. This suggests that either moderate or strong absorption may be preventing their detection in the ROSAT energy band. The comparison of our BAT catalogue with the Fermi Large Area Telescope First Source Catalogue identifies 59 BAT/Fermi correspondences: 48 blazars, 3 Seyfert galaxies, 1 interacting galaxy, 3 high mass X-ray binaries, and 4 pulsars/supernova remnants. This small number of correspondences indicates that different populations make the sky shine in these two different energy bands

The Swift-BAT hard X-ray sky monitoring unveils the orbital period of the HMXB IGR J16493-4348

IGR J16493-4348 is a supergiant high mass X-ray binary discovered by INTEGRAL in 2004. The source is detected at a significance level of $\sim21$ standard deviations in the Swift-BAT survey data collected during the first 54 months of the Swift mission. The timing analysis reveals an orbital period of $\sim$6.78 days and the presence of a full eclipse of the compact ob\ ject. The dynamical range (variability up to a factor $\sim$20) observed during the BAT monitoring suggests that IGR J16493-4348 is a wind-fed system. The derived semi-major axis of the binary system is \sim55 R_{\sun} with an orbit eccentr\ icity lower than 0.15.Comment: 4 pages, 6 figures. Accepted for publication in MNRA