The Role of Collective Neutrino Flavor Oscillations in Core-Collapse Supernova Shock Revival

We explore the effects of collective neutrino flavor oscillations due to neutrino-neutrino interactions on the neutrino heating behind a stalled core-collapse supernova shock. We carry out axisymmetric (2D) radiation-hydrodynamic core-collapse supernova simulations, tracking the first 400 ms of the post-core-bounce evolution in 11.2 solar mass and 15 solar mass progenitor stars. Using inputs from these 2D simulations, we perform neutrino flavor oscillation calculations in multi-energy single-angle and multi-angle single-energy approximations. Our results show that flavor conversions do not set in until close to or outside the stalled shock, enhancing heating by not more than a few percent in the most optimistic case. Consequently, we conclude that the postbounce pre-explosion dynamics of standard core-collapse supernovae remains unaffected by neutrino oscillations. Multi-angle effects in regions of high electron density can further inhibit collective oscillations, strengthening our conclusion.Comment: v2: Added multi-angle calculations. Conclusions unchanged. 16 pages, 7 figures. Accepted to Phys. Rev. D after revisions: 15 Sept 2011 (major), 24 Jan 2012 (minor

What factors are most influential in increasing cervical cancer screening attendance? An online study of UK-based women1

Objective: Cervical cancer is the fourth most commonly occurring cancer in women worldwide. The UK has one of the highest cervical screening rates in Europe, yet attendance has been decreasing. This study aimed to identify barriers and facilitators to screening attendance and assess the perceived importance of these factors. Methods: 194 women living in the UK were recruited via an online research recruitment website to an online survey. Most participants (N = 128, 66.0%) were currently up-to-date with cervical screening, 66 participants (34.0%) had never been screened, or were overdue for screening. Participants identified barriers and facilitators to cervical screening attendance via free-text responses and were also asked to rate a list of factors as most to least influential over decision making. Results were analysed using thematic content analysis and ratings analysed using multivariable analyses. Results: The most commonly reported barriers were: Pain/discomfort; Embarrassment; and Time. These were also rated as most influential for decision making. The most commonly reported facilitators were: Ease of making appointments; Peace of mind; and Fear of cancer/preventing serious illness. While importance rating of barriers did not differ by previous screening behaviour, ratings of some facilitators significantly differed. Up-to-date women rated believing screening is potentially life-saving and part of personal responsibility as significantly more important than overdue/never screened women. Conclusion: This study confirmed that factors which encourage screening are key to the decision of whether to attend screening. Women suggested several improvements that might make attending easier and improve uptake, including flexibility of screening locations to fit around work hours and childcare arrangements. Psychological facilitators included the peace of mind that screening brings and the belief that cervical cancer screening is potentially life-saving. Public health interventions should target factors which facilitate screening and how these interplay with barriers in order to improve uptake

Word matching using single closed contours for indexing handwritten historical documents

Effective indexing is crucial for providing convenient access to scanned versions of large collections of historically valuable handwritten manuscripts. Since traditional handwriting recognizers based on optical character recognition (OCR) do not perform well on historical documents, recently a holistic word recognition approach has gained in popularity as an attractive and more straightforward solution (Lavrenko et al. in proc. document Image Analysis for Libraries (DIAL’04), pp. 278–287, 2004). Such techniques attempt to recognize words based on scalar and profile-based features extracted from whole word images. In this paper, we propose a new approach to holistic word recognition for historical handwritten manuscripts based on matching word contours instead of whole images or word profiles. The new method consists of robust extraction of closed word contours and the application of an elastic contour matching technique proposed originally for general shapes (Adamek and O’Connor in IEEE Trans Circuits Syst Video Technol 5:2004). We demonstrate that multiscale contour-based descriptors can effectively capture intrinsic word features avoiding any segmentation of words into smaller subunits. Our experiments show a recognition accuracy of 83%, which considerably exceeds the performance of other systems reported in the literature

Correlated Gravitational Wave and Neutrino Signals from General-Relativistic Rapidly Rotating Iron Core Collapse

We present results from a new set of 3D general-relativistic hydrodynamic simulations of rotating iron core collapse. We assume octant symmetry and focus on axisymmetric collapse, bounce, the early postbounce evolution, and the associated gravitational wave (GW) and neutrino signals. We employ a finite-temperature nuclear equation of state, parameterized electron capture in the collapse phase, and a multi-species neutrino leakage scheme after bounce. The latter captures the important effects of deleptonization, neutrino cooling and heating and enables approximate predictions for the neutrino luminosities in the early evolution after core bounce. We consider 12-solar-mass and 40-solar-mass presupernova models and systematically study the effects of (i) rotation, (ii) progenitor structure, and (iii) postbounce neutrino leakage on dynamics, GW, and, neutrino signals. We demonstrate, that the GW signal of rapidly rotating core collapse is practically independent of progenitor mass and precollapse structure. Moreover, we show that the effects of neutrino leakage on the GW signal are strong only in nonrotating or slowly rotating models in which GW emission is not dominated by inner core dynamics. In rapidly rotating cores, core bounce of the centrifugally-deformed inner core excites the fundamental quadrupole pulsation mode of the nascent protoneutron star. The ensuing global oscillations (f~700-800 Hz) lead to pronounced oscillations in the GW signal and correlated strong variations in the rising luminosities of antineutrino and heavy-lepton neutrinos. We find these features in cores that collapse to protoneutron stars with spin periods <~ 2.5 ms and rotational energies sufficient to drive hyper-energetic core-collapse supernova explosions. Hence, joint GW + neutrino observations of a core collapse event could deliver strong evidence for or against rapid core rotation. [abridged]Comment: 29 pages, 14 figures. Replaced with version matching published versio

Working with and for social enterprises: the role of the volunteer ethnographer

Purpose – This paper considers the specific opportunities and challenges of engaging in ethnographic research with organisations in which the researcher participates as a volunteer ethnographer. Design/methodology/approach – The findings in this paper are based on four years of ethnographic research within a social enterprise. Findings – This paper finds that there are significant benefits of the role of the volunteer ethnographer and suggests ways to address some of the challenges. Research limitations/implications – As the field of social enterprise and ethnography grows and researchers engage with methodological discussions about participant observation, the authors suggest that attention should also be paid to the specifics of the role of the volunteer ethnographer. Originality/value – There is growing interest in the use of ethnography in social enterprises. This paper offers unique insight into how this methodology has been applied in the context of self-reliant groups and the importance of the engaging with discussion about the specific role of the volunteer ethnographer

Integrated plasmonic circuitry on a vertical-cavity surface-emitting semiconductor laser platform

Integrated plasmonic sources and detectors are imperative in the practical development of plasmonic circuitry for bio- and chemical sensing, nanoscale optical information processing, as well as transducers for high-density optical data storage. Here we show that vertical-cavity surface-emitting lasers (VCSELs) can be employed as an on-chip, electrically pumped source or detector of plasmonic signals, when operated in forward or reverse bias, respectively. To this end, we experimentally demonstrate surface plasmon polariton excitation, waveguiding, frequency conversion and detection on a VCSEL-based plasmonic platform. The coupling efficiency of the VCSEL emission to waveguided surface plasmon polariton modes has been optimized using asymmetric plasmonic nanostructures. The plasmonic VCSEL platform validated here is a viable solution for practical realizations of plasmonic functionalities for various applications, such as those requiring sub-wavelength field confinement, refractive index sensitivity or optical near-field transduction with electrically driven sources, thus enabling the realization of on-chip optical communication and lab-on-a-chip devices

Indoor environmental quality (IEQ) analysis of a low energy wind catcher with horizontally-arranged heat transfer devices

Windcatchers are natural ventilation systems based on the design of traditional architecture, intended to provide ventilation by manipulating pressure differentials around buildings induced by wind movement and temperature difference. Though the movement of air caused by the wind catcher will lead to a cooling sensation for occupants, the high air temperature in hot climates will result in little cooling or thermal discomfort to occupants. In order to improve the cooling performance by wind catchers, heat transfer devices were incorporated into the design. This work will investigate the indoor environment quality performance of a roof-mounted cooling windcatcher integrated with horizontally-arranged heat transfer devices (HHTD) using Computational Fluid Dynamics (CFD) and field test analysis. The windcatcher model was incorporated to a 5mx5mx3m test room model. The study employed the CFD code FLUENT with the standard k- model to conduct the steady-state RANS simulation. For the indoor CO2 concentration analysis, a simplified exhalation model was used and the room was filled with 12 occupants. The CO2 concentration analysis showed that the system was capable of delivering fresh air inside the space and lowering the CO2 levels. Thermal comfort analysis using the Predicted Mean Vote (PMV) was conducted whereby the measurements ranged from slightly-cool (-0.96) to slightly warm range (0.36 to 0.60). Field test measurements were carried out in the Ras-Al-Khaimah (RAK), UAE during the month of September. Numerical model was validated using experimental data and good agreement was observed between both methods of analysis