34 research outputs found

    Resolved Imaging of the HR 8799 Debris Disk with Herschel

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    We present Herschel far-infrared and submillimeter maps of the debris disk associated with the HR 8799 planetary system. We resolve the outer disk emission at 70, 100, 160 and 250 um and detect the disk at 350 and 500 um. A smooth model explains the observed disk emission well. We observe no obvious clumps or asymmetries associated with the trapping of planetesimals that is a potential consequence of planetary migration in the system. We estimate that the disk eccentricity must be <0.1. As in previous work by Su et al. (2009), we find a disk with three components: a warm inner component and two outer components, a planetesimal belt extending from 100 - 310 AU, with some flexibility (+/- 10 AU) on the inner edge, and the external halo which extends to ~2000 AU. We measure the disk inclination to be 26 +/- 3 deg from face-on at a position angle of 64 deg E of N, establishing that the disk is coplanar with the star and planets. The SED of the disk is well fit by blackbody grains whose semi-major axes lie within the planetesimal belt, suggesting an absence of small grains. The wavelength at which the spectrum steepens from blackbody, 47 +/- 30 um, however, is short compared to other A star debris disks, suggesting that there are atypically small grains likely populating the halo. The PACS longer wavelength data yield a lower disk color temperature than do MIPS data (24 and 70 um), implying two distinct halo dust grain populations.Comment: 13 pages, 8 figures (6 color), accepted for publication in the Astrophysical Journa

    Characteristics and prevalence of hardcore smokers attending UK general practitioners

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    BACKGROUND: Smoking remains a public health problem and although unsolicited GPs' advice against smoking causes between one and three percent of smokers to stop, a significant proportion of smokers are particularly resistant to the notion of stopping smoking. These resistant smokers have been called "hardcore smokers" and although 16% of smokers in the community are hardcore, little is known about hardcore smokers presenting to primary care physicians. Consequently, this study reports the characteristics and prevalence of hardcore smokers attending UK GPs. METHODS: A cross-sectional survey using data from two different research projects was conducted. Data for this analysis had been collected from surgery consultation sessions with 73 GPs in Leicestershire, England, (42 GPs from one project). Research assistants distributed pre-consultation questionnaires to 4147 adults attending GPs' surgery sessions. Questionnaires identified regular smokers, the proportion of hardcore smokers and their characteristics. Non-hardcore and hardcore smokers' ages, gender and nicotine addiction levels were compared. RESULTS: 1170 regular smokers attended surgery sessions and, 16.1% (95% CI, 14.1 to 18.4) were hardcore smokers. Hardcore smokers had higher levels of nicotine addiction than others (p = 0.000), measured by the Heaviness of Smoking Index and were more likely to be male [50.5% hardcore versus 35.3% non-hardcore, (OR = 1.88, 95% CI = 1.4 to 2.6)] but no age differences were observed between groups. CONCLUSION: A significant minority of the smokers who present in general practice are resistant to the notion of smoking cessation and these smokers are more heavily nicotine addicted than others. Although clinical guidelines suggest that GPs should regularly advise all smokers against smoking, it is probable that hardcore smokers do not respond positively to this and help to make up the 97%–99% of smokers who do not quit after being advised to stop smoking by GPs. General practitioners need to find approaches for raising the issue of smoking during consultations in ways that do not reinforce the negative opinions of hardcore smokers concerning smoking cessation

    Comparing helpful and hindering processes in good and poor outcome cases : a qualitative metasynthesis of eight Hermeneutic Single Case Efficacy Design studies

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    Objective: We tested qualitative metasynthesis of a series of Hermeneutic Single Case Efficacy Design (HSCED) studies as a method for comparing within-session processes that may explain good and poor therapeutic outcome. Method: We selected eight HSCED studies according to change in clients' scores on the Strathclyde Inventory (SI), a brief self-report instrument used to measure outcome in person-centered psychotherapy. Four of the case studies investigated the experience of clients whose pre-post change in SI scores showed improvement by the end of therapy, and the other four focused on clients whose change in SI scores indicated deterioration. We conducted a qualitative metasynthesis, adopting a generic descriptive-interpretive approach to analyze and compare the data generated by the HSCED studies. Results: In contrast to improvers, deteriorators appeared to be less ready to engage in therapeutic work at the beginning of therapy, and found the process more difficult; their therapists were less able to respond to these difficulties in a responsive, empathic manner; deteriorators were less able to cope successfully with changes of therapist and, eventually, gave up on therapy. Conclusion: We found that our qualitative metasynthesis of a series of HSCED studies produced a plausible explanation for the contrasting outcomes that occurred

    First Resolved Scattered-Light Images of Four Debris Disks in Scorpius-Centaurus with the Gemini Planet Imager

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    We present the first spatially resolved scattered-light images of four debris disks around members of the Scorpius-Centaurus (Sco-Cen) OB association with high-contrast imaging and polarimetry using the Gemini Planet Imager (GPI). All four disks are resolved for the first time in polarized light, and one disk is also detected in total intensity. The three disks imaged around HD 111161, HD 143675, and HD 145560 are symmetric in both morphology and brightness distribution. The three systems span a range of inclinations and radial extents. The disk imaged around HD 98363 shows indications of asymmetries in morphology and brightness distribution, with some structural similarities to the HD 106906 planet-disk system. Uniquely, HD 98363 has a wide comoving stellar companion, Wray 15-788, with a recently resolved disk with very different morphological properties. HD 98363 A/B is the first binary debris disk system with two spatially resolved disks. All four targets have been observed with ALMA, and their continuum fluxes range from one nondetection to one of the brightest disks in the region. With the new results, a total of 15 A/F stars in Sco-Cen have resolved scattered-light debris disks, and approximately half of these systems exhibit some form of asymmetry. Combining the GPI disk structure results with information from the literature on millimeter fluxes and imaged planets reveals a diversity of disk properties in this young population. Overall, the four newly resolved disks contribute to the census of disk structures measured around A/F stars at this important stage in the development of planetary systems

    Prefrontal cortex activation and young driver behaviour: a fNIRS study

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    Road traffic accidents consistently show a significant over-representation for young, novice and particularly male drivers. This research examines the prefrontal cortex activation of young drivers and the changes in activation associated with manipulations of mental workload and inhibitory control. It also considers the explanation that a lack of prefrontal cortex maturation is a contributing factor to the higher accident risk in this young driver population. The prefrontal cortex is associated with a number of factors including mental workload and inhibitory control, both of which are also related to road traffic accidents. This experiment used functional near infrared spectroscopy to measure prefrontal cortex activity during five simulated driving tasks: one following task and four overtaking tasks at varying traffic densities which aimed to dissociate workload and inhibitory control. Age, experience and gender were controlled for throughout the experiment. The results showed that younger drivers had reduced prefrontal cortex activity compared to older drivers. When both mental workload and inhibitory control increased prefrontal cortex activity also increased, however when inhibitory control alone increased there were no changes in activity. Along with an increase in activity during overtaking manoeuvres, these results suggest that prefrontal cortex activation is more indicative of workload in the current task. There were no differences in the number of overtakes completed by younger and older drivers but males overtook significantly more than females. We conclude that prefrontal cortex activity is associated with the mental workload required for overtaking. We additionally suggest that the reduced activation in younger drivers may be related to a lack of prefrontal maturation which could contribute to the increased crash risk seen in this population

    Histidine dipeptides are key regulators of excitation-contraction coupling in cardiac muscle: evidence from a novel CARNS1 knockout rat model

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    Histidine-containing dipeptides (HCDs) are abundantly expressed in striated muscles. Although important properties have been ascribed to HCDs, including H+ buffering, regulation of Ca2+ transients and protection against oxidative stress, it remains unknown whether they play relevant functions in vivo. To investigate the in vivo roles of HCDs, we developed the first carnosine synthase knockout (CARNS1-/-) rat strain to investigate the impact of an absence of HCDs on skeletal and cardiac muscle function. Male wild-type (WT) and knockout rats (4 months-old) were used. Skeletal muscle function was assessed by an exercise tolerance test, contractile function in situ and muscle buffering capacity in vitro. Cardiac function was assessed in vivo by echocardiography and cardiac electrical activity by electrocardiography. Cardiomyocyte contractile function was assessed in isolated cardiomyocytes by measuring sarcomere contractility, along with the determination of Ca2+ transient. Markers of oxidative stress, mitochondrial function and expression of proteins were also evaluated in cardiac muscle. Animals were supplemented with carnosine (1.8% in drinking water for 12 weeks) in an attempt to rescue tissue HCDs levels and function. CARNS1-/- resulted in the complete absence of carnosine and anserine, but it did not affect exercise capacity, skeletal muscle force production, fatigability or buffering capacity in vitro, indicating that these are not essential for pH regulation and function in skeletal muscle. In cardiac muscle, however, CARNS1-/- resulted in a significant impairment of contractile function, which was confirmed both in vivo and ex vivo in isolated sarcomeres. Impaired systolic and diastolic dysfunction were accompanied by reduced intracellular Ca2+ peaks and slowed Ca2+ removal, but not by increased markers of oxidative stress or impaired mitochondrial respiration. No relevant increases in muscle carnosine content were observed after carnosine supplementation. Results show that a primary function of HCDs in cardiac muscle is the regulation of Ca2+ handling and excitation-contraction coupling

    First Resolved Scattered-light Images of Four Debris Disks in Scorpius-Centaurus with the Gemini Planet Imager

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    We present the first spatially resolved scattered-light images of four debris disks around members of the Scorpius-Centaurus (Sco-Cen) OB association with high-contrast imaging and polarimetry using the Gemini Planet Imager (GPI). All four disks are resolved for the first time in polarized light, and one disk is also detected in total intensity. The three disks imaged around HD 111161, HD 143675, and HD 145560 are symmetric in both morphology and brightness distribution. The three systems span a range of inclinations and radial extents. The disk imaged around HD 98363 shows indications of asymmetries in morphology and brightness distribution, with some structural similarities to the HD 106906 planet–disk system. Uniquely, HD 98363 has a wide comoving stellar companion, Wray 15-788, with a recently resolved disk with very different morphological properties. HD 98363 A/B is the first binary debris disk system with two spatially resolved disks. All four targets have been observed with ALMA, and their continuum fluxes range from one nondetection to one of the brightest disks in the region. With the new results, a total of 15 A/F stars in Sco-Cen have resolved scattered-light debris disks, and approximately half of these systems exhibit some form of asymmetry. Combining the GPI disk structure results with information from the literature on millimeter fluxes and imaged planets reveals a diversity of disk properties in this young population. Overall, the four newly resolved disks contribute to the census of disk structures measured around A/F stars at this important stage in the development of planetary systems

    Protoplanetary Disk Science Enabled by Extremely Large Telescopes

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    The processes that transform gas and dust in circumstellar disks into diverse exoplanets remain poorly understood. One key pathway is to study exoplanets as they form in their young (∼few~Myr) natal disks. Extremely Large Telescopes (ELTs) such as GMT, TMT, or ELT, can be used to establish the initial chemical conditions, locations, and timescales of planet formation, via (1)~measuring the physical and chemical conditions in protoplanetary disks using infrared spectroscopy and (2)~studying planet-disk interactions using imaging and spectro-astrometry. Our current knowledge is based on a limited sample of targets, representing the brightest, most extreme cases, and thus almost certainly represents an incomplete understanding. ELTs will play a transformational role in this arena, thanks to the high spatial and spectral resolution data they will deliver. We recommend a key science program to conduct a volume-limited survey of high-resolution spectroscopy and high-contrast imaging of the nearest protoplanetary disks that would result in an unbiased, holistic picture of planet formation as it occurs

    Socioeconomic deprivation and illness trajectory in the Scottish population after COVID-19 hospitalization

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    Background The associations between deprivation and illness trajectory after hospitalisation for coronavirus disease-19 (COVID-19) are uncertain. Methods A prospective, multicentre cohort study was conducted on post-COVID-19 patients, enrolled either in-hospital or shortly post-discharge. Two evaluations were carried out: an initial assessment and a follow-up at 28–60 days post-discharge. The study encompassed research blood tests, patient-reported outcome measures, and multisystem imaging (including chest computed tomography (CT) with pulmonary and coronary angiography, cardiovascular and renal magnetic resonance imaging). Primary and secondary outcomes were analysed in relation to socioeconomic status, using the Scottish Index of Multiple Deprivation (SIMD). The EQ-5D-5L, Brief Illness Perception Questionnaire (BIPQ), Patient Health Questionnaire-4 (PHQ-4) for Anxiety and Depression, and the Duke Activity Status Index (DASI) were used to assess health status. Results Of the 252 enrolled patients (mean age 55.0 ± 12.0 years; 40% female; 23% with diabetes), deprivation status was linked with increased BMI and diabetes prevalence. 186 (74%) returned for the follow-up. Within this group, findings indicated associations between deprivation and lung abnormalities (p = 0.0085), coronary artery disease (p = 0.0128), and renal inflammation (p = 0.0421). Furthermore, patients with higher deprivation exhibited worse scores in health-related quality of life (EQ-5D-5L, p = 0.0084), illness perception (BIPQ, p = 0.0004), anxiety and depression levels (PHQ-4, p = 0.0038), and diminished physical activity (DASI, p = 0.002). At the 3-month mark, those with greater deprivation showed a higher frequency of referrals to secondary care due to ongoing COVID-19 symptoms (p = 0.0438). However, clinical outcomes were not influenced by deprivation. Conclusions In a post-hospital COVID-19 population, socioeconomic deprivation was associated with impaired health status and secondary care episodes. Deprivation influences illness trajectory after COVID-19
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