1,305 research outputs found

    Do Water Fountain Jets Really Indicate the Onset of the Morphological Metamorphosis of Circumstellar Envelopes?

    Get PDF
    The small-scale bipolar jets having short dynamical ages from "water fountain (WF)" sources are regarded as an indication of the onset of circumstellar envelope morphological metamorphosis of intermediate-mass stars. Such process usually happens at the end of the asymptotic giant branch (AGB) phase. However, recent studies found that WFs could be AGB stars or even early planetary nebulae. This fact prompted the idea that WFs may not necessarily be objects at the beginning of the morphological transition process. In the present work, we show that WFs could have different envelope morphologies by studying their spectral energy distribution profiles. Some WFs have spherical envelopes that resembles usual AGB stars, while others have aspherical envelopes which are more common to post-AGB stars. The results imply that WFs may not represent the earliest stage of the morphological metamorphosis. We further argue that the dynamical age of a WF jet, which can be calculated from maser proper motions, may not be the real age of the jet. The dynamical age cannot be used to justify the moment when the envelope begins to become aspherical, nor to tell the concrete evolutionary status of the object. A WF jet could be the innermost part of a larger well-developed jet, which is not necessarily a young jet.Comment: 21 pages, 4 figures, accepted for publication in MNRA

    Do water fountain jets really indicate the onset of the morphological metamorphosis of circumstellar envelopes?

    Full text link
    Small-scale bipolar jets with short dynamical ages from 'water-fountain' (WF) sources are regarded as an indication of the onset of circumstellar envelope morphological metamorphosis of intermediate-mass stars. Such a process usually happens at the end of the asymptotic giant branch (AGB) phase. However, recent studies found that WFs could be AGB stars or even early planetary nebulae. This fact prompted the idea that WFs may not necessarily be objects at the beginning of the morphological transition process. In the present work, we show that WFs could have different envelope morphologies by studying their spectral energy distribution profiles. SomeWFs have spherical envelopes that resemble usual AGB stars, while others have aspherical envelopes, which are more common to post-AGB stars. The results imply that WFs may not represent the earliest stage of morphological metamorphosis. We argue further that the dynamical age of a WF jet, which can be calculated from maser proper motions, may not be the real age of the jet. The dynamical age cannot be used to justify the moment when the envelope begins to become aspherical, nor to tell the concrete evolutionary status of the object. A WF jet could be the innermost part of a larger well-developed jet, which is not necessarily a young jet. © 2016 The Authors

    Identification of oxygen-rich late/post-asymptotic giant branch stars and water fountains via maser and infrared criteria

    Full text link
    The transitional phase between the asymptotic giant branch (AGB) and post-AGB phases holds the key to our understanding of the late-stage metamorphosis of intermediate-mass stars. In particular, high velocity jets forming during this phase are suggested to contribute significantly to the shaping of planetary nebulae. For oxygen-rich stars, the rare "water fountains (WFs)" have been regarded as representative objects in this phase, and it is important to identify more of them for further studies. Here we briefly report the results of our latest OH and H2O maser surveys in which a new WF candidate (IRAS 19356+0754) was found. We also performed radiative transfer modelling on the spectral energy distributions (SEDs) of all known WFs. It is concluded that WFs might in fact not be the transitional objects, as opposed to previous belief. WFs could be AGB or post-AGB stars with no obvious similarities amongst their SEDs. Further efforts are still needed to improve the identification criteria.This work is supported by a grant awarded to JN from the Research Grants Council of Hong Kong (project code: HKU 703308P; HKU 704209P; HKU 704710P)

    Vertical and longitudinal electron density structures of equatorial E- and F-regions

    Get PDF
    From global soundings of ionospheric electron density made with FORMOSAT 3/COSMIC satellites for September 2006–August 2009, day-night variations in vertical and longitudinal structures of the electron densities in equatorial E- and F-regions for different seasons are investigated for the first time. The results reveal that the wavenumber-3 and wavenumber-4 patterns dominated the nighttime (22:00–04:00 LT) F-region longitudinal structures in solstice and in equinox seasons, respectively. In daytime (08:00–18:00 LT) F-region, the wavenumber-4 patterns governed the longitudinal structures in the September equinox and December solstice, and wavenumber-3 in March equinox and June solstice respectively. A comparison of the daytime and nighttime longitudinal electron density structures indicates that they are approximately 180° out of phase with each other. It is believed that this out of phase relation is very likely the result of the opposite phase relation between daytime and nighttime nonmigrating diurnal tidal winds that modulate background E-region dynamo electric field at different places, leading to the day-night change in the locations of the equatorial plasma fountains that are responsible for the formation of the F-region longitudinal structures. Further, a good consistency between the locations of the density structures in the same seasons of the different years for both daytime and nighttime epochs has been noticed indicating that the source mechanism for these structures could be the same

    Collapse of stamps for soft lithography due to interfacial adhesion

    Get PDF
    Collapse of elastomeric elements used for pattern transfer in soft lithography is studied through experimental measurements and theoretical modehng. The objective is to identify the driving force for such collapse. Two potential driving forces, the self-weight of the stamp and the interfacial adhesion, are investigated. An idealized configuration of periodic rectangular grooves and flat punches is considered. Experimental observations demonstrate that groove collapse occurs regardless of whether the gravitational force promotes or suppresses such collapse, indicating that self-weight is not the driving force. On the other hand, model predictions based on the postulation that interfacial adhesion is the driving force exhibit excellent agreement with the experimentally measured collapse behavior. The interfacial adhesion energy is also evaluated by matching an adhesion parameter in the model with the experimental data.open546

    Effect of Intravenous Golimumab on Fatigue and the Relationship with Clinical Response in Adults with Active Ankylosing Spondylitis in the Phase 3 GO-ALIVE Study

    Get PDF
    INTRODUCTION: We studied the effect of intravenous (IV)-golimumab on fatigue and the association of fatigue improvement with clinical response post hoc in adults with active ankylosing spondylitis (AS) in the GO-ALIVE trial. METHODS: Patients were randomized to IV-golimumab 2 mg/kg (N = 105) at week (W) 0, W4, then every 8 W (Q8W) or placebo (N = 103) at W0, W4, W12, crossover to IV-golimumab 2 mg/kg at W16, W20, then Q8W through W52. Fatigue measures included Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) Question #1 (fatigue; 0 [none], 10 [worst]; decrease indicates improvement) and 36-Item Short Form Health Survey (SF-36) vitality subscale (0 [worst], 100 [best]; increase indicates improvement). Minimum clinically important difference is ≥ 1 for BASDAI-fatigue and ≥ 5 for SF-36 vitality. GO-ALIVE primary endpoint was Assessment of SpondyloArthritis international Society ≥ 20% improvement criteria (ASAS20). Other clinical outcomes assessed included other ASAS responses, Ankylosing Spondylitis Disease Activity Score, and Bath Ankylosing Spondylitis Functional Index score. The distribution-based minimally important differences (MIDs) were determined for BASDAI-fatigue and SF-36 vitality. The relationship between improvement in fatigue and clinical outcomes was assessed via multivariable logistic regression. RESULTS: Mean changes in BASDAI-fatigue/SF-36 vitality scores were greater with IV-golimumab versus placebo at W16 (- 2.74/8.46 versus - 0.73/2.08, both nominal p ≤ 0.003); by W52 (after crossover), differences between groups narrowed (- 3.18/9.39 versus - 3.07/9.17). BASDAI-fatigue/SF-36 vitality MIDs were achieved by greater proportions of IV-golimumab-treated versus placebo-treated patients at W16 (75.2%/71.4% versus 42.7%/35.0%). A one-point/five-point improvement in BASDAI-fatigue/SF-36 vitality scores at W16 increased likelihood of achieving ASAS20 (odds ratios [95% confidence intervals]: 3.15 [2.21, 4.50] and 2.10 [1.62, 2.71], respectively) and ASAS40 (3.04 [2.15, 4.28] and 2.24 [1.68, 3.00], respectively) responses at W16; concurrent improvements and clinical response at W52 were consistent. A one-point/five-point improvement in BASDAI-fatigue/SF-36 vitality scores at W16 predicted increased likelihood of achieving ASAS20 (1.62 [1.35, 1.95] and 1.52 [1.25, 1.86], respectively) and ASAS40 (1.62 [1.37, 1.92] and 1.44 [1.20, 1.73], respectively) responses at W52. CONCLUSIONS: IV-golimumab provided important and sustained fatigue improvement in patients with AS that positively associated with achieving clinical response. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT02186873

    'Unable to have a proper conversation over the phone about my concerns': a multimethods evaluation of the impact of COVID-19 on routine childhood vaccination services in London, UK

    Get PDF
    Objectives Investigating the completion rate of 12-month vaccinations and parental perspectives on vaccine services during COVID-19. Study-design Service evaluation including parental questionnaire. Methods Uptake of 12-month vaccinations in three London general practices during three periods: pre-COVID (1/3/2018–28/2/2019, n = 826), during COVID (1/3/2019–28/2/2020, n = 775) and post-COVID first wave (1/8/2020–31/1/2021, n = 419). Questionnaire of parents whose children were registered at the practices (1/4/2019–1/22/2021, n = 1350). Results Comparing pre-COVID and both COVID cohorts, the completion rates of 12-month vaccines were lower. Haemophilus influenzae type B/meningococcal group C (Hib/MenC) vaccination uptake was 5.6% lower (89.0% vs 83.4%, P=<0.001), meningococcal group B (MenB) booster uptake was 4.4% lower (87.3% vs 82.9%, P = 0.006), pneumococcal conjugate vaccine (PCV) booster uptake was 6% lower (88.0% vs 82.0%, P < 0.001) and measles, mumps and rubella (MMR) vaccine uptake was 5.2% lower (89.1% vs 83.9%, P = 0.003). Black/Black-British ethnicity children had increased odds of missing their 12-month vaccinations compared to White ethnicity children (adjusted odds ratio 0.43 [95% confidence interval 0.24–0.79, P = 0.005; 0.36 [0.20–0.65], P < 0.001; 0.48 [0.27–0.87], P = 0.01; 0.40 [0.22–0.73], P = 0.002; for Hib/MenC, MenB booster, PCV booster and MMR. Comparing pre-COVID and COVID periods, vaccinations coded as not booked increased for MMR (10%), MenB (7%) and PCV booster (8%). Parents reported changes to vaccination services during COVID-19, including difficulties booking and attending appointments and lack of vaccination reminders. Conclusion A sustained decrease in 12-month childhood vaccination uptake disproportionally affected Black/Black British ethnicity infants during the first wave of the pandemic. Vaccination reminders and availability of healthcare professionals to discuss parental vaccine queries are vital to maintaining uptake

    Flexible and Stretchable Self-Powered Multi-Sensors Based on the N-Type Thermoelectric Response of Polyurethane/Na-x(Ni-ett)(n) Composites

    Get PDF
    Flexible and stretchable electronic devices have a broad range of potential uses, from biomedicine, soft robotics, and health monitoring to the internet‐of‐things. Unfortunately, finding a robust and reliable power source remains challenging, particularly in off‐the‐grid and maintenance‐free applications. A sought‐after development overcome this challenge is the development of autonomous, self‐powered devices. A potential solution is reported exploiting a promising n‐type thermoelectric compound, poly nickel‐ethenetetrathiolates (Na_{x}(Ni‐ett)_{n}). Highly stretchable n‐type composite films are obtained by combining Nax(Ni‐ett)n with commercial polyurethane (Lycra). As high as 50 wt% Na_{x}(Ni‐ett)_{n} content composite film can withstand deformations of ≈500% and show conductivities of ≈10^{-2} S cm^{-1} and Seebeck coefficients of approx. −40 µV K^{-1}. These novel materials can be easily synthesized on a large scale with continuous processes. When subjected to a small temperature difference (<20 °C), the films generate sufficient thermopower to be used for sensing strain (gauge factor ≈20) and visible light (sensitivity factor ≈36% (kW m^{-2})^{-1}), independent of humidity (sensitivity factor ≈0.1 (%RH)^{-1}. As a proof‐of‐concept, a wearable self‐powered sensor is demonstrated by using n‐type Na_{x}(Ni‐ett)_{n}/Lycra and PEDOT:PSS/Lycra elements, connected in series by hot pressing, without employing any metal connections, hence preserving good mechanical ductility and ease of processing
    corecore