Phase-lock loop frequency control and the dropout problem

Technique automatically sets the frequency of narrow band phase-lock loops within automatic lock-in-range. It presets a phase-lock loop to a desired center frequency with a closed loop electronic frequency discriminator and holds the phase-lock loop to that center frequency until lock is achieved

Simulating star formation in molecular cloud cores IV. The role of turbulence and thermodynamics

We perform SPH simulations of the collapse and fragmentation of low-mass cores having different initial levels of turbulence (alpha_turb=0.05,0.10,0.25). We use a new treatment of the energy equation which captures the transport of cooling radiation against opacity due to both dust and gas (including the effects of dust sublimation, molecules, and H^- ions). We also perform comparison simulations using a standard barotropic equation of state. We find that -- when compared with the barotropic equation of state -- our more realistic treatment of the energy equation results in more protostellar objects being formed, and a higher proportion of brown dwarfs; the multiplicity frequency is essentially unchanged, but the multiple systems tend to have shorter periods (by a factor ~3), higher eccentricities, and higher mass ratios. The reason for this is that small fragments are able to cool more effectively with the new treatment, as compared with the barotropic equation of state. We find that the process of fragmentation is often bimodal. The first protostar to form is usually, at the end, the most massive, i.e. the primary. However, frequently a disc-like structure subsequently forms round this primary, and then, once it has accumulated sufficient mass, quickly fragments to produce several secondaries. We believe that this delayed fragmentation of a disc-like structure is likely to be an important source of very low-mass hydrogen-burning stars and brown dwarfs.Comment: 14 pages, 8 figures. Accepted for publication by A&

SCUBA observations of the Horsehead Nebula - what did the horse swallow?

We present observations taken with SCUBA on the JCMT of the Horsehead Nebula in Orion (B33), at wavelengths of 450 and 850 \mum. We see bright emission from that part of the cloud associated with the photon-dominated region (PDR) at the `top' of the horse's head, which we label B33-SMM1. We characterise the physical parameters of the extended dust responsible for this emission, and find that B33-SMM1 contains a more dense core than was previously suspected. We compare the SCUBA data with data from the Infrared Space Observatory (ISO) and find that the emission at 6.75-\mum is offset towards the west, indicating that the mid-infrared emission is tracing the PDR while the submillimetre emission comes from the molecular cloud core behind the PDR. We calculate the virial balance of this core and find that it is not gravitationally bound but is being confined by the external pressure from the HII region IC434, and that it will either be destroyed by the ionising radiation, or else may undergo triggered star formation. Furthermore we find evidence for a lozenge-shaped clump in the `throat' of the horse, which is not seen in emission at shorter wavelengths. We label this source B33-SMM2 and find that it is brighter at submillimetre wavelengths than B33-SMM1. SMM2 is seen in absorption in the 6.75-\mum ISO data, from which we obtain an independent estimate of the column density in excellent agreement with that calculated from the submillimetre emission. We calculate the stability of this core against collapse and find that it is in approximate gravitational virial equilibrium. This is consistent with it being a pre-existing core in B33, possibly pre-stellar in nature, but that it may also eventually undergo collapse under the effects of the HII region.Comment: 11 pages, 6 figures, accepted by MNRA

ATRA mechanically reprograms pancreatic stellate cells to suppress matrix remodelling and inhibit cancer cell invasion

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a dismal survival rate. Persistent activation of pancreatic stellate cells (PSCs) can perturb the biomechanical homoeostasis of the tumour microenvironment to favour cancer cell invasion. Here we report that ATRA, an active metabolite of vitamin A, restores mechanical quiescence in PSCs via a mechanism involving a retinoic acid receptor beta (RAR-β)-dependent downregulation of actomyosin (MLC-2) contractility. We show that ATRA reduces the ability of PSCs to generate high traction forces and adapt to extracellular mechanical cues (mechanosensing), as well as suppresses force-mediated extracellular matrix remodelling to inhibit local cancer cell invasion in 3D organotypic models. Our findings implicate a RAR-β/MLC-2 pathway in peritumoural stromal remodelling and mechanosensory-driven activation of PSCs, and further suggest that mechanical reprogramming of PSCs with retinoic acid derivatives might be a viable alternative to stromal ablation strategies for the treatment of PDAC

What do people do with porn? qualitative research into the consumption, use and experience of pornography and other sexually explicit media

This article reviews qualitative research into the consumption of pornography and other sexually explicit media emerging from a range of subject areas. Taking a critique of quantitative methods and a focus on measuring sexual effects and attitudes as a starting point, it considers the proposition that qualitative work is more suited to an examination of the complex social, cultural and political constructions of sexuality. Examining studies into the way men, women and young people see, experience, and use explicit media texts, the article identifies the key findings that have emerged. Qualitative work shows that sexuality explicit media texts are experienced and understood in a variety of ways and evoke strong and often contradictory reactions, not all of which are represented in public debates about pornography. These texts function in a range of different ways, depending on context; as a source of knowledge, a resource for intimate practices, a site for identity construction, and an occasion for performing gender and sexuality. The article reviews these studies and their findings, identifying what they suggest about directions for future research, both in terms of developing methodology and refining approaches to sexuality and media consumption.</p

Youth Use of E-Liquid Flavours – A systematic review exploring patterns of use of e liquid flavours and associations with continued vaping, tobacco smoking uptake, or cessation

Background and Aims: There is concern that young people may be attracted to e-liquid flavours, prompting long-term vaping in naive users and potentially subsequent tobacco smoking. We aimed to review the use of e-liquid flavours by young people and describe associations with uptake or cessation of both regular vaping and tobacco smoking, adverse effects and subjective experiences. Design: Systematic review, including interventional, observational and qualitative studies reporting on the use of e-cigarette flavours by young people (aged < 18 years). Setting: Studies published in English language from any country or cultural setting. Participants: Young people and their carers (aged < 18 years). Measurements: A meta-analysis was not possible due to substantial heterogeneity, inconsistency in reporting of flavour categorizations and non-interventional study designs; thus, we narratively report findings. Findings: In total, 58 studies were included. The quality of the evidence was extremely low. Most (n = 39) studies were cross-sectional survey designs. In total, 11 longitudinal cohort studies assessed trajectories; eight qualitative studies reported on user experiences. Studies reported views and experiences of a total of 512 874 young people. Both cross-sectional and longitudinal studies suggested that flavours are important for initiation and continuation of vaping. Qualitative evidence shows interest and enjoyment in flavours. There was judged to be insufficient evidence that use of e-liquid flavours specifically is associated with uptake of smoking. No studies found clear associations between flavours and cessation in this population. We found no included reports of adverse effects of flavours. Conclusions: Flavours may be an important motivator for e-cigarette uptake, but the role of flavours in tobacco smoking uptake or cessation is unclear. The quality of the evidence on use of e-cigarette flavours by young people is low overall

Research in development: learning from the CGIAR Research Program on Aquatic Agricultural Systems

This working paper aims to synthesize and share learning from the experience of adapting and operationalizing the Research in Development (RinD) approach to agricultural research in the five hubs under the The CGIAR Research Program on Aquatic Agricultural Systems. It seeks to share learning about how the approach is working in context and to explore the outcomes it is achieving through initial implementation over 3 ½ years. This learning can inform continuation of agricultural research in the second phase of the CGIAR research programs and will be useful to others aiming to implement research programs that seek to equitably build capacity to innovate in complex social-ecological systems. Each of the chapters in this working paper have shown that RinD has produced a range of outcomes that were often unexpected and broader in scope than might result from other approaches to agricultural research. RinD also produces innovations, and there is evidence that it builds capacity to innovate. - See more at: http://www.aas.cgiar.org/publications/research-development-learning-cgiar-research-program-aquatic-agricultural-systems#sthash.xfjhbHpl.dpu

Will the introduction of non-invasive prenatal diagnostic testing erode informed choices? An experimental study of health care professionals

Objective. Informed choice is a fundamental concept within prenatal care. The present study assessed the extent to which the introduction of non-invasive prenatal diagnosis (NIPD) of Down's syndrome may undermine the process of making informed choices to undergo prenatal testing or screening for Down's syndrome by altering the quality and quantity of pre-test counselling. Methods. 231 obstetricians and midwives were randomly allocated one of three vignettes, each describing a different type of test: (a) invasive prenatal diagnosis (IPD), (b) non-invasive prenatal diagnosis (NIPD) or (c) Down's syndrome screening (DSS). Participants were then asked to complete a questionnaire assessing (1) the information considered important to communicate to women, (2) whether test offer and uptake should take place on different days, and (3) whether signed consent forms should be obtained prior to testing. Results. Across the three test types, five out of the seven presented topics were considered equally important to communicate, including the information that testing is the woman's choice. Compared with participants receiving the IPD vignette, those receiving the NIPD and DSS vignettes were less likely to report that counselling and testing should occur on different days (IPD 94.7% versus 74.1% and 73.9% for NIPD and DSS respectively, p = .001) and that written consent was a necessity (IPD 96.1% versus 68.3% and 75.4% for NIPD and DSS respectively, p < .001). Conclusion. This study provides the first empirical evidence to demonstrate that practitioners may view the consent process for NIPD differently to IPD. There is potential for the introduction of NIPD to undermine women making informed choices in the context of prenatal diagnostic testing for conditions like DS. Practice implications. Given the importance of informed choice in reproductive decision-making, implementation of any programme based on NIPD should be designed to facilitate this. Keywords: Informed choice; Prenatal; Down's syndrome; Non-invasive testingThis article was written by Dr Ainsley Newson during the time of her employment with the University of Bristol, UK (2006-2012). Self-archived in the Sydney eScholarship Repository with permission of Bristol University, Sept 2014