9,671 research outputs found

    Multi-wavelength Radio Continuum Emission Studies of Dust-free Red Giants

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    Multi-wavelength centimeter continuum observations of non-dusty, non-pulsating K spectral-type red giants directly sample their chromospheres and wind acceleration zones. Such stars are feeble emitters at these wavelengths however, and previous observations have provided only a small number of modest S/N measurements slowly accumulated over three decades. We present multi-wavelength Karl G. Jansky Very Large Array thermal continuum observations of the wind acceleration zones of two dust-free red giants, Arcturus (Alpha Boo: K2 III) and Aldebaran (Alpha Tau: K5 III). Importantly, most of our observations of each star were carried out over just a few days, so that we obtained a snapshot of the different stellar atmospheric layers sampled at different wavelengths, independent of any long-term variability. We report the first detections at several wavelengths for each star including a detection at 10 cm (3.0 GHz: S band) for both stars and a 20 cm (1.5 GHz: L band) detection for Alpha Boo. This is the first time single luminosity class III red giants have been detected at these continuum wavelengths. Our long-wavelength data sample the outer layers of Alpha Boo's atmosphere where its wind velocity is approaching its terminal value and the ionization balance is becoming frozen-in. For Alpha Tau, however, our long-wavelength data are still sampling its inner atmosphere, where the wind is still accelerating probably due to its lower mass-loss rate. We compare our data with published semi-empirical models based on ultraviolet data, and the marked deviations highlight the need for new atmospheric models to be developed. Spectral indices are used to discuss the possible properties of the stellar atmospheres, and we find evidence for a rapidly cooling wind in the case of Alpha Boo. Finally, we develop a simple analytical wind model for Alpha Boo based on our new long-wavelength flux measurements

    Modeling of the hydrogen Lyman lines in solar flares

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    The hydrogen Lyman lines (91.2 nm < λ < 121.6 nm) are significant contributors to the radiative losses of the solar chromosphere, and they are enhanced during flares. We have shown previously that the Lyman lines observed by the Extreme Ultraviolet Variability instrument onboard the Solar Dynamics Observatory exhibit Doppler motions equivalent to speeds on the order of 30 km s−1. However, contrary to expectations, both redshifts and blueshifts were present and no dominant flow direction was observed. To understand the formation of the Lyman lines, particularly their Doppler motions, we have used the radiative hydrodynamic code, RADYN, along with the radiative transfer code, RH, to simulate the evolution of the flaring chromosphere and the response of the Lyman lines during solar flares. We find that upflows in the simulated atmospheres lead to blueshifts in the line cores, which exhibit central reversals. We then model the effects of the instrument on the profiles, using the Extreme Ultraviolet Variability Experiment (EVE) instrument's properties. What may be interpreted as downflows (redshifted emission) in the lines, after they have been convolved with the instrumental line profile, may not necessarily correspond to actual downflows. Dynamic features in the atmosphere can introduce complex features in the line profiles that will not be detected by instruments with the spectral resolution of EVE, but which leave more of a signature at the resolution of the Spectral Investigation of the Coronal Environment instrument onboard the Solar Orbiter

    Temporal Evolution of the Size and Temperature of Betelgeuse's Extended Atmosphere

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    We use the Very Large Array (VLA) in the A configuration with the Pie Town (PT) Very Long Baseline Array (VLBA) antenna to spatially resolve the extended atmosphere of Betelgeuse over multiple epochs at 0.7, 1.3, 2.0, 3.5, and 6.1 cm. The extended atmosphere deviates from circular symmetry at all wavelengths while at some epochs we find possible evidence for small pockets of gas significantly cooler than the mean global temperature. We find no evidence for the recently reported e-MERLIN radio hotspots in any of our multi-epoch VLA/PT data, despite having sufficient spatial resolution and sensitivity at short wavelengths, and conclude that these radio hotspots are most likely interferometric artefacts. The mean gas temperature of the extended atmosphere has a typical value of 3000 K at 2 RR_{\star} and decreases to 1800 K at 6 RR_{\star}, in broad agreement with the findings of the single epoch study from Lim et al. (1998). The overall temperature profile of the extended atmosphere between 2Rr6R2 R_{\star} \lesssim r \lesssim 6 R_{\star} can be described by a power law of the form Tgas(r)r0.6T_{\mathrm{gas}}(r) \propto r^{-0.6}, with temporal variability of a few 100 K evident at some epochs. Finally, we present over 12 years of V band photometry, part of which overlaps our multi-epoch radio data. We find a correlation between the fractional flux density variability at V band with most radio wavelengths. This correlation is likely due to shock waves induced by stellar pulsations, which heat the inner atmosphere and ionize the more extended atmosphere through radiative means. Stellar pulsations may play an important role in exciting Betelgeuse's extended atmosphere

    A review of malaria vaccine clinical projects based on the WHO rainbow table

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    Development and Phase 3 testing of the most advanced malaria vaccine, RTS,S/AS01, indicates that malaria vaccine R&D is moving into a new phase. Field trials of several research malaria vaccines have also confirmed that it is possible to impact the host-parasite relationship through vaccine-induced immune responses to multiple antigenic targets using different platforms. Other approaches have been appropriately tested but turned out to be disappointing after clinical evaluation

    Thomas Graham Brown (1882–1965): Behind the Scenes at the Cardiff Institute of Physiology

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    Thomas Graham Brown undertook seminal experiments on the neural control of locomotion between 1910 and 1915. Although elected to the Royal Society in 1927, his locomotion research was largely ignored until the 1960s when it was championed and extended by the distinguished neuroscientist, Anders Lundberg. Puzzlingly, Graham Brown's published research stopped in the 1920s and he became renowned as a mountaineer. In this article, we review his life and multifaceted career, including his active neurological service in WWI. We outline events behind the scenes during his tenure at Cardiff's Institute of Physiology in Wales, UK, including an interview with his technician, Terrence J. Surman, who worked in this institute for over half a century

    Human Research Ethics Committee Experiences and Views About Children's Participation in Research: Results From the MESSI Study.

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    As part of a larger study, Australian Human Research Ethics Committee (HREC) members and managers were surveyed about their decision-making and views about social research studies with child participants. Responses of 229 HREC members and 42 HREC managers are reported. While most HREC members had received ethical training, HREC training and guidelines specific to research involving children were rare. Most applications involving children had to go through a full ethical review, but few adverse events were reported to HRECs regarding the conduct of the studies. Revisions to study proposals requested by HRECs were mostly related to consent processes and age-appropriate language. One-third of HREC members said that they would approve research on any topic. Most were also concerned that the methodology was appropriate, and the risks and benefits were clearly articulated. Specific training and guidance are needed to increase HREC members' confidence to judge ethical research with children

    Demographic characteristics and perceptions of supply and demand of chiropractic services in Australia: Results from stage 1 of the work force study survey

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    Objectives: The aim of this report is to describe the demographic characteristics including the age profile, gender differences, income and perceptions of supply and demand of the chiropractic profession in Australia. This workforce study (WFS) was divided into three components, Australian Chiropractors (Stage 1), their patients (Stage 2), and members of the general public (Stage 3). Methods: A web-based, 64-item, cross-sectional survey questionnaire was issued to registered chiropractors (CAA and non-CAA members) throughout Australia in 2010. At the time of the survey there were 3,892 registered chiropractors. Survey invitations were sent to those who were registered chiropractors, and had provided email addresses (n=1,917). Results: Demographic Characteristics: There is evidence to suggest that the profession may be becoming increasingly female over time. Income exclusively from chiropractic care included 27.9% who reported an annual pre-tax net income of 115,000orlessand32.3115,000 or less and 32.3% earned more than 115,000. Of the latter group, 12% indicated that they were earning more than $215,000. Income was not related to the hours worked per week particularly for males. Supply and Demand: When considering their home state and their local region, more chiropractors thought that there was undersupply in their state, but an adequate supply in their local region. A large proportion (40%) of the sample felt that universities in Australia were graduating the correct number of chiropractors per year, and 32% reported that too many were being produced in Australia. Very few reported that the Universities were not graduating enough chiropractors. Conclusion: This paper reflects some of the findings from Stage 1 of the three stage Workforce study, showing a profession heading towards a more even gender balance and characterised by a higher than average annual income. Future research should include the impact on supply and demand of the possibility of an increasingly female profession. In addition to this, although there is a perception that there is under-utilisation of chiropractic services in inland, rural and remote areas, the extent of which should be further explored. Information from this study will assist with strategic decision making and planning. A strategic framework for the profession should not only consider the findings from this study but also explore other factors that may have an impact on supply and demand, for example general trends in health and aging from local and national government reports

    Simple and objective prediction of survival in patients with lung cancer: staging the host systemic inflammatory response

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    Background. Prediction of survival in patients diagnosed with lung cancer remains problematical. The aim of the present study was to examine the clinical utility of an established objective marker of the systemic inflammatory response, the Glasgow Prognostic Score, as the basis of risk stratification in patients with lung cancer. Methods. Between 2005 and 2008 all newly diagnosed lung cancer patients coming through the multidisciplinary meetings (MDTs) of four Scottish centres were included in the study. The details of 882 patients with a confirmed new diagnosis of any subtype or stage of lung cancer were collected prospectively. Results. The median survival was 5.6 months (IQR 4.8–6.5). Survival analysis was undertaken in three separate groups based on mGPS score. In the mGPS 0 group the most highly predictive factors were performance status, weight loss, stage of NSCLC, and palliative treatment offered. In the mGPS 1 group performance status, stage of NSCLC, and radical treatment offered were significant. In the mGPS 2 group only performance status and weight loss were statistically significant. Discussion. This present study confirms previous work supporting the use of mGPS in predicting cancer survival; however, it goes further by showing how it might be used to provide more objective risk stratification in patients diagnosed with lung cancer

    Chiropractic in Australia: A survey of the general public

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    Background: An increase in the use of complementary and alternative medicine was identified in several countries including Australia. There is a need to assess the current position of chiropractic within the Australian health system. Objectives: To estimate the lifetime prevalence of the use of chiropractic in Australia; to investigate the perceptions and attitudes of Australian general public about: their health status, the chiropractic profession, chiropractic and health services in general. Methods: A survey was carried out in which a novel 21-item questionnaire was utilised. To obtain a sample whose opinions would be representative of the Australian general population with a 95% level of significance and 4% margin of error, 600 respondents were required. Descriptive statistics, the chi-squared test and logistic regression were used to present and analyse the data. Results: 757 respondents completed the survey. A high prevalence of pain and discomfort relating to the musculoskeletal system were found, particularly in the lower back (71.1 % of the respondents) and neck (55.6%). The first contact with respect to therapy for the greatest proportion of respondents was general medicine (35.5%), followed by chiropractic (16%), physiotherapy (13.8%) and massage (10.2%). Physiotherapy was rated highest in its ability to relieve the symptoms (18%) followed by chiropractic (15.9%), massage (15.5%) and medicine (14%). In our sample 302 (39.9%) participants used chiropractic before and 75.9% of these consumers were satisfied or highly satisfied with the services provided. No significant differences in income, age and gender were found with regards to those individuals who reported a previous use of chiropractic services. The main reasons for not using chiropractic were: that there was no perceived need for a chiropractic intervention, associated cost, lack of information about chiropractic, lack of referral, being attended by another health professional, and concern about the safety and efficacy of the treatment. Most of the respondents considered that attending to general health and well-being was more important than simply alleviating symptoms and their personal philosophy was a major determinant when it came to the choice of health services. Conclusions: This study suggests that chiropractic is a thriving profession in Australia. It would appear that there is a need for chiropractic services in Australia, particularly in attending to the highly prevalent realm of musculoskeletal disorders. A considerable number of Australians already utilise chiropractic services. Encouragingly, the vast majority of these consumers are satisfied with the service provided. Chiropractic could play an even greater role within the Australian health if better integrated with the mainstream and allied medicine. A more active approach should be taken by chiropractic practitioners and institutions to improve the general public's knowledge about chiropractic

    Navigating China game publishing::a case study of Steam China

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    This case study focuses on engagement with publishing platforms in China and involves a collaboration with Steam China. Our goal was to develop a playable game prototype that was both framed and informed by China publishing and market expertise. By developing the game concept and pitch from the ground up with these restrictions and requirements in mind, our hope was that the resulting case study would serve as a useful pathfinder for other UK-based developers who want to learn more about game publishing for China markets
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