55 resultados para activity level


Relevância:

100.00% 100.00%

Publicador:

Resumo:

To compare aerobic capacity, strength, flexibility, and activity level in extremely low birth weight (ELBW) adolescents at 17 years of age with term-born control subjects.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

Context. The magnetic activity of planet-hosting stars is an importantfactor for estimating the atmospheric stability of close-in exoplanetsand the age of their host stars. It has long been speculated thatclose-in exoplanets can influence the stellar activity level. However,testing for tidal or magnetic interaction effects in samples ofplanet-hosting stars is difficult because stellar activity hindersexoplanet detection, so that stellar samples with detected exoplanetsshow a bias toward low activity for small exoplanets.

Aims: Weaim to test whether exoplanets in close orbits influence the stellarrotation and magnetic activity of their host stars.

Methods: Wedeveloped a novel approach to test for systematic activity-enhancementsin planet-hosting stars. We use wide (several 100 AU) binary systems inwhich one of the stellar components is known to have an exoplanet, whilethe second stellar component does not have a detected planet andtherefore acts as a negative control. We use the stellar coronal X-rayemission as an observational proxy for magnetic activity and analyzeobservations performed with Chandra and XMM-Newton.

Results: Wefind that in two systems for which strong tidal interaction can beexpected the planet-hosting primary displays a much higher magneticactivity level than the planet-free secondary. In three systems forwhich weaker tidal interaction can be expected the activity levels ofthe two stellar components agree with each other.

Conclusions:Our observations indicate that the presence of Hot Jupiters may inhibitthe spin-down of host stars with thick outer convective layers. Possiblecauses for this effect include a transfer of angular momentum from theplanetary orbit to the stellar rotation through tidal interaction, ordifferences during the early evolution of the system, where the hoststar may decouple from the protoplanetary disk early because of a gapopened by the forming Hot Jupiter.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

As the ESA Rosetta mission approached, orbited, and sent a lander to comet 67P/Churyumov-Gerasimenko in 2014, a large campaign of ground-based observations also followed the comet. We constrain the total activity level of the comet by photometry and spectroscopy to place Rosetta results in context and to understand the large-scale structure of the comet's coma pre-perihelion. We performed observations using a number of telescopes, but concentrate on results from the 8m VLT and Gemini South telescopes in Chile. We use R-band imaging to measure the dust coma contribution to the comet's brightness and UV-visible spectroscopy to search for gas emissions, primarily using VLT/FORS. In addition we imaged the comet in near-infrared wavelengths (JHK) in late 2014 with Gemini-S/Flamingos 2. We find that the comet was already active in early 2014 at heliocentric distances beyond 4 au. The evolution of the total activity (measured by dust) followed previous predictions. No gas emissions were detected despite sensitive searches. The comet maintains a similar level of activity from orbit to orbit, and is in that sense predictable, meaning that Rosetta results correspond to typical behaviour for this comet. The gas production (for CN at least) is highly asymmetric with respect to perihelion, as our upper limits are below the measured production rates for similar distances post-perihelion in previous orbits.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The microsporidian parasite, Pleistophora mulleri, infects the abdominal muscle of the freshwater amphipod Gammarus duebeni celticus. We recently showed that P. mulleri infection was associated with G. d. celticus hosts being more vulnerable to predation by the invasive amphipod Gammarus pulex. Parasitized G. d. celticus also had a reduced ability to prey upon other co-occurring amphipods. We suggested the parasite may have pervasive influences on host ecology and behaviour. Here, we examine the association between P. mulleri parasitism and parameters influencing individual host fitness, behaviour and interspecific interactions. We also investigate the relationship between parasite prevalence and host population structure in the field. In our G. d. celticus study population, P. mulleri prevalence was strongly seasonal, ranging from 8.5% in summer to 44.9% in winter. The relative abundance of hosts with the heaviest parasite burden increased during summer, which coincided with high host mortality, suggesting that parasitism may regulate host abundance to some degree. Females were more likely to be parasitized than males and parasitized males were paired with smaller females than unparasitized males. Parasitism was associated with reduction in the host's activity level and reduced both its predation on the isopod Asellus aquaticus and aggression towards precopula pairs of the invasive G. pulex. We discuss the pervasive influence of this parasite on the ecology of its host.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Objective: To compare an accelerated intervention incorporating early therapeutic exercise after acute ankle sprains with a standard protection, rest, ice, compression, and elevation intervention.

Design: Randomised controlled trial with blinded outcome assessor.

Setting: Accident and emergency department and university based sports injury clinic.

Participants: 101 patients with an acute grade 1 or 2 ankle sprain.

Interventions: Participants were randomised to an accelerated intervention with early therapeutic exercise (exercise group) or a standard protection, rest, ice, compression, and elevation intervention (standard group).

Main outcome measures: The primary outcome was subjective ankle function (lower extremity functional scale). Secondary outcomes were pain at rest and on activity, swelling, and physical activity at baseline and at one, two, three, and four weeks after injury. Ankle function and rate of reinjury were assessed at 16 weeks.

Results: An overall treatment effect was in favour of the exercise group (P=0.0077); this was significant at both week 1 (baseline adjusted difference in treatment 5.28, 98.75% confidence interval 0.31 to 10.26; P=0.008) and week 2 (4.92, 0.27 to 9.57; P=0.0083). Activity level was significantly higher in the exercise group as measured by time spent walking (1.2 hours, 95% confidence interval 0.9 to 1.4 v 1.6, 1.3 to 1.9), step count (5621 steps, 95% confidence interval 4399 to 6843 v 7886, 6357 to 9416), and time spent in light intensity activity (53 minutes, 95% confidence interval 44 to 60 v 76, 58 to 95). The groups did not differ at any other time point for pain at rest, pain on activity, or swelling. The reinjury rate was 4% (two in each group).

Conclusion: An accelerated exercise protocol during the first week after ankle sprain improved ankle function; the group receiving this intervention was more active during that week than the group receiving standard care.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

We report the discovery of a new transiting planet in the southern hemisphere. It was found by the WASP-south transit survey and confirmed photometrically and spectroscopically by the 1.2 m Swiss Euler telescope, LCOGT 2m Faulkes South Telescope, the 60 cm TRAPPIST telescope, and the ESO 3.6 m telescope. The orbital period of the planet is 2.94 days. We find that it is a gas giant with a mass of 0.88 ± 0.10 MJ and an estimated radius of 0.96 ± 0.05 RJ. We obtained spectra during transit with the HARPS spectrograph and detect the Rossiter-McLaughlin effect despite its small amplitude. Because of the low signal-to-noise ratio of the effect and a small impact parameter, we cannot place a strong constraint on the projected spin-orbit angle. We find two conflicting values for the stellar rotation. We find, via spectral line broadening, that v sin I = 2.2 ± 0.3 km s-1, while applying another method, based on the activity level using the index log R'_HK, gives an equatorial rotation velocity of only v = 1.35 ± 0.20 km s-1. Using these as priors in our analysis, the planet might be either misaligned or aligned. This result raises doubts about the use of such priors. There is evidence of neither eccentricity nor any radial velocity drift with time. Using WASP-South photometric observations confirmed with LCOGT Faulkes South Telescope, the 60 cm TRAPPIST telescope, the CORALIE spectrograph and the camera from the Swiss 1.2 m Euler Telescope placed at La Silla, Chile, as well as with the HARPS spectrograph, mounted on the ESO 3.6 m, also at La Silla, under proposal 084.C-0185. The data is publicly available at the CDS Strasbourg and on demand to the main author.RV data is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/531/A24Appendix is available in electronic form at http://www.aanda.org

Relevância:

60.00% 60.00%

Publicador:

Resumo:

We present new X-ray observations obtained with Chandra ACIS-S of the HD 189733 system, consisting of a K-type star orbited by a transiting Hot Jupiter and an M-type stellar companion. We report a detection of the planetary transit in soft X-rays with a significantly deeper transit depth than observed in the optical. The X-ray data favor a transit depth of 6%-8%, versus a broadband optical transit depth of 2.41%. While we are able to exclude several possible stellar origins for this deep transit, additional observations will be necessary to fully exclude the possibility that coronal inhomogeneities influence the result. From the available data, we interpret the deep X-ray transit to be caused by a thin outer planetary atmosphere which is transparent at optical wavelengths, but dense enough to be opaque to X-rays. The X-ray radius appears to be larger than the radius observed at far-UV wavelengths, most likely due to high temperatures in the outer atmosphere at which hydrogen is mostly ionized. We furthermore detect the stellar companion HD 189733B in X-rays for the first time with an X-ray luminosity of log LX = 26.67 erg s-1. We show that the magnetic activity level of the companion is at odds with the activity level observed for the planet-hosting primary. The discrepancy may be caused by tidal interaction between the Hot Jupiter and its host star.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Context. Close-in, giant planets are expected to influence their host stars via tidal or magnetic interaction. But are these effects in X-rays strong enough in suitable targets known so far to be observed with today's instrumentation? Aims: The υ And system, an F8V star with a Hot Jupiter, was observed to undergo cyclic changes in chromospheric activity indicators with its innermost planet's period. We aim to investigate the stellar chromospheric and coronal activity over several months. Methods: We therefore monitored the star in X-rays as well as at optical wavelengths to test coronal and chromospheric activity indicators for planet-induced variability, making use of the Chandra X-ray Observatory as well as the echelle spectrographs FOCES and HRS at Calar Alto (Spain) and the Hobby-Eberly Telescope (Texas, US). Results: The stellar activity level is low, as seen both in X-rays as in Ca ii line fluxes; the chromospheric data show variability with the stellar rotation period. We do not find activity variations in X-rays or in the optical that can be traced back to the planet. Conclusions: Gaining observational evidence of star-planet interactions in X-rays remains challenging.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Aims: X-ray emission is an important diagnostics to study magnetic activity in very low mass stars that are presumably fully convective and have an effectively neutral photosphere. Methods: We investigate an XMM-Newton observation of SCR 1845-6357, a nearby, ultracool M 8.5 / T 5.5 dwarf binary. The binary is unresolved in the XMM detectors, but the X-ray emission is very likely from the M 8.5 dwarf. We compare its flaring emission to those of similar very low mass stars and additionally present an XMM observation of the M 8 dwarf VB 10. Results: We detect quasi-quiescent X-ray emission from SCR 1845-6357 at soft X-ray energies in the 0.2-2.0 keV band, as well as a strong flare with a count rate increase of a factor of 30 and a duration of only 10 min. The quasi-quiescent X-ray luminosity of log LX = 26.2 erg/s and the corresponding activity level of log LX/Lbol = -3.8 point to a fairly active star. Coronal temperatures of up to 5 MK and frequent minor variability support this picture. During the flare, which is accompanied by a significant brightening in the near-UV, plasma temperatures of 25-30 MK are observed and an X-ray luminosity of LX = 8 × 1027 erg/s is reached. Conclusions: The source SCR 1845-6357 is a nearby, very low mass star that emits X-rays at detectable levels in quasi-quiescence, implying the existence of a corona. The high activity level, coronal temperatures and the observed large flare point to a rather active star, despite its estimated age of a few Gyr.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Stellar activity can produce large amounts of high-energy radiation, which is absorbed by the planetary atmosphere leading to irradiation-driven mass loss. We present the detection and an investigation of high-energy emission in a transiting super-Earth host system, GJ 1214, based on XMM-Newton observations. We derive an X-ray luminosity of LX = 7.4 × 1025 erg s-1 and a corresponding activity level of log (LX /L bol) ~ -5.3. Further, we determine a coronal temperature of about ~3.5 MK, which is typical for coronal emission of moderately active low-mass stars. We estimate that GJ 1214 b evaporates at a rate of 1.3× 1010 g s-1 and has lost a total of ≈2-5.6 M ⊕.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Planets may have effects on their host stars by tidal or magnetic interaction. Such star-planet interactions are thought to enhance the activity level of the host star. However, stellar activity also affects the sensitivity of planet detection methods. Samples of planet-hosting stars which are investigated for such star-planet interactions are therefore subject to strong selection effects which need to be taken into account.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

We assessed motor laterality in sheep to explore species-specific brain hemi-field dominance and how this could be affected by genetic or developmental factors. Further, we investigated whether directionality and strength of laterality could be linked to emotional stress in ewes and their lambs during partial separation. Forty-three ewes and their singleton lambs were scored on the (left/right) direction of turn in a y-maze to rejoin a conspecific (laterality test). Further, their behavioural response (i.e. time spent near the fence, vocalisations, and activity level) during forced separation by an open-mesh fence was assessed (separation test). Individual laterality was recorded for 44.2 % ewes (significant right bias) and 81.4 % lambs (equally biased to the left and the right). There was no significant association in side bias between dams and offspring. The Chi-squared test revealed a significant population bias for both groups (p < 0.05). Evolutionary adaptive strategies or stimuli-related visual laterality may provide explanation for this decision-making process. Absolute strength of laterality (irrespective of side) was high (Kolmogorov–Smirnov test, dams: D = 0.2; p < 0.001; lambs: D = 0.36, p < 0.0001). The Wilcoxon test showed that lateralised lambs and dams spent significantly more time near each other during separation than non-lateralised animals (p < 0.05), and that lateralised dams were also more active than non-lateralised ones. Arguably, the lateralised animals showed a greater attraction to their pair because they were more disturbed and thus required greater reassurance. The data show that measures of laterality offer a potential novel non-invasive indicator of separation stress.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

BACKGROUND: The needs of children with autism spectrum disorder (ASD) are complex and this is reflected in the number and diversity of outcomes assessed and measurement tools used to collect evidence about children's progress. Relevant outcomes include improvement in core ASD impairments, such as communication, social awareness, sensory sensitivities and repetitiveness; skills such as social functioning and play; participation outcomes such as social inclusion; and parent and family impact.

OBJECTIVES: To examine the measurement properties of tools used to measure progress and outcomes in children with ASD up to the age of 6 years. To identify outcome areas regarded as important by people with ASD and parents.

METHODS: The MeASURe (Measurement in Autism Spectrum disorder Under Review) research collaboration included ASD experts and review methodologists. We undertook systematic review of tools used in ASD early intervention and observational studies from 1992 to 2013; systematic review, using the COSMIN checklist (Consensus-based Standards for the selection of health Measurement Instruments) of papers addressing the measurement properties of identified tools in children with ASD; and synthesis of evidence and gaps. The review design and process was informed throughout by consultation with stakeholders including parents, young people with ASD, clinicians and researchers.

RESULTS: The conceptual framework developed for the review was drawn from the International Classification of Functioning, Disability and Health, including the domains 'Impairments', 'Activity Level Indicators', 'Participation', and 'Family Measures'. In review 1, 10,154 papers were sifted - 3091 by full text - and data extracted from 184; in total, 131 tools were identified, excluding observational coding, study-specific measures and those not in English. In review 2, 2665 papers were sifted and data concerning measurement properties of 57 (43%) tools were extracted from 128 papers. Evidence for the measurement properties of the reviewed tools was combined with information about their accessibility and presentation. Twelve tools were identified as having the strongest supporting evidence, the majority measuring autism characteristics and problem behaviour. The patchy evidence and limited scope of outcomes measured mean these tools do not constitute a 'recommended battery' for use. In particular, there is little evidence that the identified tools would be good at detecting change in intervention studies. The obvious gaps in available outcome measurement include well-being and participation outcomes for children, and family quality-of-life outcomes, domains particularly valued by our informants (young people with ASD and parents).

CONCLUSIONS: This is the first systematic review of the quality and appropriateness of tools designed to monitor progress and outcomes of young children with ASD. Although it was not possible to recommend fully robust tools at this stage, the review consolidates what is known about the field and will act as a benchmark for future developments. With input from parents and other stakeholders, recommendations are made about priority targets for research.

FUTURE WORK: Priorities include development of a tool to measure child quality of life in ASD, and validation of a potential primary outcome tool for trials of early social communication intervention.

STUDY REGISTRATION: This study is registered as PROSPERO CRD42012002223.

FUNDING: The National Institute for Health Research Health Technology Assessment programme.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

OBJECTIVE: To compare an accelerated intervention incorporating early therapeutic exercise after acute ankle sprains with a standard protection, rest, ice, compression, and elevation intervention.

DESIGN: Randomised controlled trial with blinded outcome assessor.

SETTING: Accident and emergency department and university based sports injury clinic.

PARTICIPANTS: 101 patients with an acute grade 1 or 2 ankle sprain.

INTERVENTIONS: Participants were randomised to an accelerated intervention with early therapeutic exercise (exercise group) or a standard protection, rest, ice, compression, and elevation intervention (standard group).

MAIN OUTCOME MEASURES: The primary outcome was subjective ankle function (lower extremity functional scale). Secondary outcomes were pain at rest and on activity, swelling, and physical activity at baseline and at one, two, three, and four weeks after injury. Ankle function and rate of reinjury were assessed at 16 weeks.

RESULTS: An overall treatment effect was in favour of the exercise group (P=0.0077); this was significant at both week 1 (baseline adjusted difference in treatment 5.28, 98.75% confidence interval 0.31 to 10.26; P=0.008) and week 2 (4.92, 0.27 to 9.57; P=0.0083). Activity level was significantly higher in the exercise group as measured by time spent walking (1.2 hours, 95% confidence interval 0.9 to 1.4 v 1.6, 1.3 to 1.9), step count (5621 steps, 95% confidence interval 4399 to 6843 v 7886, 6357 to 9416), and time spent in light intensity activity (53 minutes, 95% confidence interval 44 to 60 v 76, 58 to 95). The groups did not differ at any other time point for pain at rest, pain on activity, or swelling. The reinjury rate was 4% (two in each group).

CONCLUSION: An accelerated exercise protocol during the first week after ankle sprain improved ankle function; the group receiving this intervention was more active during that week than the group receiving standard care.

TRIAL REGISTRATION: Current Controlled Trials ISRCTN13903946.