The influence of binarity on the morpho-kinematics of planetary nebulae

The role of central star binarity in the shaping of planetary nebulae (PNe) has been the subject of much debate, with single stars believed to be incapable of producing the most highly collimated morphologies. However, observational support for binary-induced shaping has been sadly lacking. Here, we highlight the results of a continuing programme to spatio-kinematically model the morphologies of all PNe known to contain a close binary central star. Spatio-kinematical modelling is imperative for these objects, as it circumvents the degeneracy between morphology and orientation which can adversely affect determinations of morphology based on imaging alone. Furthermore, spatio-kinematical modelling accurately determines the orientation of the nebular shell, allowing the theoretically predicted perpendicular alignment, between nebular symmetry axis and binary orbital plane, to be tested. To date, every PN subjected to this investigation has displayed the predicted alignment, indicating that binarity has played an important role in the formation and evolution of these nebulae. The further results from this programme will be key, not only in determining whether binary interaction is responsible for shaping the studied PNe, but also in assessing the importance of binarity in the formation and evolution of all PNe in general.Comment: 2 pages, 2 tables, proceedings of the IAU Symposium No. 283, Planetary Nebulae: An Eye to the Futur

CMOS system for high throughput fluorescence lifetime sensing using time correlated single photon counting

Fluorescence lifetime sensing using time correlated single photon counting (TCSPC) is a key analytical tool for molecular and cell biology research, medical diagnosis and pharmacological development. However, commercially available TCSPC equipment is bulky, expensive and power hungry, typically requiring iterative software post-processing to calculate the fluorescence lifetime. Furthermore, the technique is restrictively slow due to a low photon throughput limit which is necessary to avoid distortions caused by TCSPC pile-up. An investigation into CMOS compatible multimodule architectures to miniaturise the standard TCSPC set up, allow an increase in photon throughput by overcoming the TCSPC pile-up limit, and provide fluorescence lifetime calculations in real-time is presented. The investigation verifies the operation of the architectures and leads to the selection of optimal parameters for the number of detectors and timing channels required to overcome the TCSPC pile-up limit by at least an order of magnitude. The parameters are used to implement a low power miniaturised sensor in a 130 nm CMOS process, combining single photon detection, multiple channel timing and embedded pre-processing of the fluorescence lifetime, all within a silicon area of < 2 mm2. Single photon detection is achieved using an array of single photon avalanche diodes (SPADs) arranged in a digital silicon photomultiplier (SiPM) architecture with a 10 % fill-factor and a compressed 250 ps output pulse, which provides a photon throughput of > 700 MHz. An array of time-interleaved time-to-digital converters (TI-TDCs) with 50 ps resolution and no processing dead-time records up to eight photon events during each excitation period, significantly reducing the effect of TCSPC pile-up. The TCSPC data is then processed using an embedded centre-of-mass method (CMM) pre-calculation to produce single exponential fluorescence lifetime estimations in real-time. The combination of high photon throughput and real-time calculation enables advances in applications such as fluorescence lifetime imaging microscopy (FLIM) and time domain fluorescence lifetime activated cell sorting. To demonstrate this, the device is validated in practical bulk sample fluorescence lifetime, FLIM and simulated flow based experiments. Photon throughputs in excess of the excitation frequency are demonstrated for a range of organic and inorganic fluorophores for minimal error in lifetime calculation by CMM (< 5 %)

mHealth: A Mediating Tool for Community Health Workers’ Transformation in Armed Conflict Zones

Communities affected by armed conflict are striving to provide access to effective healthcare services in countries like Nigeria, where there exists a fragile healthcare system with an acute deficit of manpower and resources. This fragility has a negative impact on child health service delivery. mHealth is considered an excellent platform for enhancing/transforming the activities of community health workers (CHWs) in the delivery of effective health services. This paper aims to explore how mHealth implementation mediates and transforms the activities of CHWs in an armed conflict setting using activity theory as a lens. An interpretive research methodology was used, and the method of data collection was done mainly by participatory observations and interviews. The findings show that the introduction of an mHealth tool can transform the activities of CHWs in various ways. The study contributes to information systems research by broadening our understanding of the implementation of mHealth in armed conflict settings

The post-common-envelope, binary central star of the planetary nebula Hen 2-11

We present a detailed photometric study of the central star system of the planetary nebula Hen 2-11, selected for study because of its low-ionisation filaments and bipolar morphology - traits which have been strongly linked with central star binarity. Photometric monitoring with NTT-EFOSC2 reveals a highly irradiated, double-eclipsing, post-common-envelope system with a period of 0.609 d. Modelling of the lightcurve indicates that the nebular progenitor is extremely hot, while the secondary in the system is probably a K-type main sequence star. The chemical composition of the nebula is analysed, showing Hen 2-11 to be a medium-excitation non-Type I nebula. A simple photoionisation model is constructed determining abundance ratios of C/O and N/O which would be consistent with the common-envelope cutting short the AGB evolution of the nebular progenitor. The detection of a post-common-envelope binary system at the heart of Hen 2-11 further strengthens the link between binary progeny and the formation of axisymmetric planetary nebulae with patterns of low-ionisation filaments, clearly demonstrating their use as morphological indicators of central star binarity.Comment: Accepted for publication in A&A. 9 pages, 5 figures, 4 table

Race–Gender Differences in the Impact of History of Heavy Drinking on Current Alcohol Consumption during the Transition to Adulthood

American youth transitioning to adulthood consume more alcohol than in any other period of the life course. This high level of consumption can result in serious consequences, including lost productivity, death and disability, sexual assault, and addiction. Nevertheless, relatively little is known, especially by race and gender, about how prior history of heavy drinking (e.g., in late adolescence) impacts drinking in young adulthood. Utilizing data from the National Longitudinal Survey of Youth (1994-2004) for African Americans, Latinos, and Whites (N = 2,300), we found that Whites and Latinos drink more than African Americans, and men report drinking more than women. However, accounting for a history of heavy drinking introduces considerable variation in current drinking patterns by race–gender status. A history of heavy drinking more than doubles the number of drinks consumed by African American women, putting their drinking levels on par with African American men and White women and raising their level of drinking above Latinas. Further, African American women\u27s probability of heavy drinking becomes indistinguishable from that of African American men and White women, once accounting for a prior history of binge drinking. For Latinas with a history of heavy drinking, the probability of being a current binge drinker is equal to Latinos and White men and higher than African Americans and White women

Automatic laser alignment for multifocal microscopy using a LCOS-SLM and a 32x32 pixel CMOS SPAD array

International audienceAlignment of a laser to a point source detector for confocal microscopy can be a time-consuming task. The problem is further exacerbated when multiple laser excitation spots are used in conjunction with a multiple pixel single photon detector; in addition to X, Y and Z positioning, pixels in a 2D array detector can also be misaligned in roll, pitch and yaw with respect to each other, causing magnification, rotation and focus variation across the array. We present a technique for automated multiple point laser alignment to overcome these issues using closed-loop feedback between a laser illuminated computer controlled Liquid Crystal on Silicon Spatial Light Modulator (LCOS-SLM) acting as the excitation source and a 32 32 pixel CMOS Single Photon Avalanche Diode (SPAD) array as the multiple pixel detection element. The alignment procedure is discussed and simulated to prove its feasibility before being implemented and tested in a practical optical system. We show that it is possible to align each independent laser point in a sub-second time scale, significantly simplifying and speeding up experimental set-up times. The approach provides a solution to the difficulties associated with multiple point confocal laser alignment to multiple point detector arrays, paving the way for further advances in applications such as Fluorescence Correlation Spectroscopy (FCS) and Fluorescence Lifetime Imaging Microscopy (FLIM)