Morphology and Oxygen Sensor Response of Luminescent Ir-Labeled Poly(dimethylsiloxane)/Polystyrene Polymer Blend Films

Polymer films consisting of a linear poly(dimethylsiloxane) end-functionalized with a luminescent Ir(III) complex (Ir−PDMS), blended with polystyrene (PS), function as optical oxygen sensors. The sensor response arises by quenching of the luminescence from the Ir(III) chromophore by oxygen that permeates into the polymer film. The morphology and luminescence oxygen sensor properties of blend films consisting of Ir−PDMS and PS have been characterized by fluorescence microscopy, atomic force microscopy, and scanning electron microscopy. The investigations demonstrate that microscale phase segregation occurs in the films. In blends that contain a relatively small amount of Ir−PDMS in PS (ca. 10 wt %), the Ir−PDMS exists as circular domains, with diameters ranging from 2 to 5 μm, surrounded by the majority PS phase. For larger weight fractions of Ir−PDMS in the blends, the film morphology becomes bicontinuous. A novel epifluorescence microscopy method is applied that allows the construction of Stern−Volmer quenching images that quantify the oxygen sensor response of the blend films with micrometer spatial resolution. These images provide a map of the oxygen permeability of the polymer blend films with a spatial resolution of ca. 1 μm. The results of this investigation show that the micrometer-sized Ir−PMDS domains display a 2−3-fold higher oxygen sensor response compared to the surrounding PS matrix. This result is consistent with the fact that PDMS is considerably more gas permeable compared to PS. The relationship of the microscale morphology of the blends to their performance as macroscale optical oxygen sensors is discussed

Absolute properties of the binary system BB Pegasi

We present a ground based photometry of the low-temperature contact binary BB Peg. We collected all times of mid-eclipses available in literature and combined them with those obtained in this study. Analyses of the data indicate a period increase of 3.0(1) x 10^{-8} days/yr. This period increase of BB Peg can be interpreted in terms of the mass transfer 2.4 x 10^{-8} Ms yr^{-1} from the less massive to the more massive component. The physical parameters have been determined as Mc = 1.42 Ms, Mh = 0.53 Ms, Rc = 1.29 Rs, Rh = 0.83 Rs, Lc = 1.86 Ls, and Lh = 0.94 Ls through simultaneous solution of light and of the radial velocity curves. The orbital parameters of the third body, that orbits the contact system in an eccentric orbit, were obtained from the period variation analysis. The system is compared to the similar binaries in the Hertzsprung-Russell and Mass-Radius diagram.Comment: 17 pages, 3 figures, accepted for Astronomical Journa

Using Schema Training to Facilitate Students\u27 Understanding of Challenging Engineering Concepts in Heat Transfer and Thermodynamics

Background: Chi and colleagues have argued that some of the most challenging engineering concepts exhibit properties of emergent systems. However, students often lack a mental framework, or schema, for understanding emergence. Slotta and Chi posited that helping students develop a schema for emergent systems, referred to as schema training, would increase the understanding of challenging concepts exhibiting emergent properties. Purpose: We tested the effectiveness of schema training and explored the nature of challenging concepts from thermodynamics and heat transfer. We investigated if schema training could (a) repair misconceptions in advanced engineering students and (b) prevent them in beginning engineering students. Method: We adapted Slotta and Chi\u27s schema training modules and tested their impact in two studies that employed an experimental design. Items from the Thermal and Transport Concept Inventory and expert-developed multiple-choice questions were used to evaluate conceptual understanding of the participants. The language used by students in their open-ended explanations of multiple-choice questions was also coded. Results: In both studies, students in the experimental groups showed larger gains in their understanding of some concepts—specifically in dye diffusion and microfluidics in Study One, and in the final test for thermodynamics in Study Two. But in neither study did students exhibit any gain in conceptual questions about heat transfer. Conclusion: Our studies suggest the importance of examining the nature of the phenomena underlying the concepts being taught because the language used in instruction has implications for how students understand them. Therefore, we suggest that instructors reflect on their own understanding of the concepts

Phase and TV Based Convex Sets for Blind Deconvolution of Microscopic Images

In this paper, two closed and convex sets for blind deconvolution problem are proposed. Most blurring functions in microscopy are symmetric with respect to the origin. Therefore, they do not modify the phase of the Fourier transform (FT) of the original image. As a result blurred image and the original image have the same FT phase. Therefore, the set of images with a prescribed FT phase can be used as a constraint set in blind deconvolution problems. Another convex set that can be used during the image reconstruction process is the Epigraph Set of Total Variation (ESTV) function. This set does not need a prescribed upper bound on the Total Variation (TV) of the image. The upper bound is automatically adjusted according to the current image of the restoration process. Both the TV of the image and the blurring filter are regularized using the ESTV set. Both the phase information set and the ESTV are closed and convex sets. Therefore they can be used as a part of any blind deconvolution algorithm. Simulation examples are presented. © 2015 IEEE

Training medical specialists to communicate better with patients with medically unexplained physical symptoms (MUPS). A randomized, controlled trial

Background Patients with medically unexplained physical symptoms (MUPS) are prevalent 25-50% in general and specialist care. Medical specialists and residents often find patients without underlying pathology difficult to deal with, whereas patients sometimes don't feel understood. We developed an evidence-based communication training, aimed to improve specialists' interviewing, information-giving and planning skills in MUPS consultations, and tested its effectiveness. Methods The intervention group in this multi-center randomized controlled trial received a 14-hour training program to which experiential learning and feedback were essential. Using techniques from Cognitive Behavioral Therapy, they were stimulated to seek interrelating factors (symptoms, cognitions, emotions, behavior, and social environment) that reinforced a patient's symptoms. They were taught to

Old World megadroughts and pluvials during the Common Era

Climate model projections suggest widespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other “Old World” climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the “Old World Drought Atlas” (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the Mediterranean Basin during the Common Era. The OWDA matches historical accounts of severe drought and wetness with a spatial completeness not previously available. In addition, megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes. The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability

Image Classification for Age-related Macular Degeneration Screening Using Hierarchical Image Decompositions and Graph Mining

Age-related Macular Degeneration (AMD) is the most common cause of adult blindness in the developed world. This paper describes a new image mining technique to perform automated detection of AMD from color fundus photographs. The technique comprises a novel hierarchical image decomposition mechanism founded on a circular and angular partitioning. The resulting decomposition is then stored in a tree structure to which a weighted frequent sub-tree mining algorithm is applied. The identified sub-graphs are then incorporated into a feature vector representation (one vector per image) to which classification techniques can be applied. The results show that the proposed approach performs both efficiently and accurately

Leading order analysis of neutrino induced dimuon events in the CHORUS experiment

We present a leading order QCD analysis of a sample of neutrino induced charged-current events with two muons in the final state originating in the lead-scintillating fibre calorimeter of the CHORUS detector. The results are based on a sample of 8910 neutrino and 430 antineutrino induced opposite-sign dimuon events collected during the exposure of the detector to the CERN Wide Band Neutrino Beam between 1995 and 1998. % with $E_{\mu 1},E_{\mu 2} > 5$ GeV and $Q^2 > 3$ GeV$^2$ collected %between 1995 and 1998. The analysis yields a value of the charm quark mass of \mc = (1.26\pm 0.16 \pm 0.09) \GeVcc and a value of the ratio of the strange to non-strange sea in the nucleon of $\kappa = 0.33 \pm 0.05 \pm 0.05$, improving the results obtained in similar analyses by previous experiments.Comment: Submitted to Nuclear Physics

Charged-Particle Multiplicities in Charged-Current Neutrino-- and Anti-Neutrino--Nucleus Interactions

The CHORUS experiment, designed to search for $\nu_{\mu}\to\nu_{\tau}$ oscillations, consists of a nuclear emulsion target and electronic detectors. In this paper, results on the production of charged particles in a small sample of charged-current neutrino-- and anti-neutrino--nucleus interactions at high energy are presented. For each event, the emission angle and the ionization features of the charged particles produced in the interaction are recorded, while the standard kinematic variables are reconstructed using the electronic detectors. The average multiplicities for charged tracks, the pseudo-rapidity distributions, the dispersion in the multiplicity of charged particles and the KNO scaling are studied in different kinematical regions. A study of quasi-elastic topologies performed for the first time in nuclear emulsions is also reported. The results are presented in a form suitable for use in the validation of Monte Carlo generators of neutrino--nucleus interactions.Comment: 17 pages, 5 figure

Associated Charm Production in Neutrino-Nucleus Interactions

In this paper a search for associated charm production both in neutral and charged current $\nu$-nucleus interactions is presented. The improvement of automatic scanning systems in the {CHORUS} experiment allows an efficient search to be performed in emulsion for short-lived particles. Hence a search for rare processes, like the associated charm production, becomes possible through the observation of the double charm-decay topology with a very low background. About 130,000 $\nu$ interactions located in the emulsion target have been analysed. Three events with two charm decays have been observed in the neutral-current sample with an estimated background of 0.18$\pm$0.05. The relative rate of the associated charm cross-section in deep inelastic $\nu$ interactions, $\sigma(c\bar{c}\nu)/\sigma_\mathrm{NC}^\mathrm{DIS}= (3.62^{+2.95}_{-2.42}({stat})\pm 0.54({syst}))\times 10^{-3}$ has been measured. One event with two charm decays has been observed in charged-current $\nu_\mu$ interactions with an estimated background of 0.18$\pm$0.06 and the upper limit on associated charm production in charged-current interactions at 90% C.L. has been found to be $\sigma (c\bar{c} \mu^-)/\sigma_\mathrm{CC} < 9.69 \times 10^{-4}$.Comment: 10 pages, 4 figure