3,252 research outputs found
Differences in physical-fitness test scores between actively and passively recruited older adults: consequences for norm-based classification
This study investigated differences in physical-fitness test scores between actively and passively recruited older adults and the consequences thereof for norm-based classification of individuals. Walking endurance, grip strength, hip flexibility, balance, manual dexterity, and reaction time were measured in participants age 57 years or older: 1 sample recruited through media announcements (passively recruited) and 1 sample recruited through personal contact (actively recruited). Classifications on a 5-point scale based on norms were cross-tabulated. Compared with the actively recruited sample, performance of the passively recruited sample was significantly better on all tests except, for women, hip flexibility and manual dexterity. Cross-tabulation of the 2 classifications showed that percentages of agreement varied from 27.4% to 87.4%. Cohen's Kappa varied from. 11 to .84. Caution should be used when giving feedback on test performance and subsequently making physical activity recommendations if norms are based on the performance of passively recruited older adults
Dust, Ice, and Gas In Time (DIGIT) Herschel program first results: A full PACS-SED scan of the gas line emission in protostar DK Chamaeleontis
Aims. We aim to study the composition and energetics of the circumstellar material of DK Cha, an intermediate-mass star in transition from an
embedded configuration to a star plus disk stage, during this pivotal stage of its evolution.
Methods. Using the range scan mode of PACS on the Herschel Space Observatory, we obtained a spectrum of DK Cha from 55 to 210 μm as part
of the DIGIT key program.
Results. Almost 50 molecular and atomic lines were detected, many more than the 7 lines detected in ISO-LWS. Nearly the entire ladder of CO
from J = 14–13 to 38–37 (E_u/k = 4080 K), water from levels as excited as J_(K−1 K+1) = 7_(07) (E_u/k = 843 K), and OH lines up to E_u/k = 290 K were
detected.
Conclusions. The continuum emission in our PACS SED scan matches the flux expected by a model consisting of a star, a surrounding disk of
0.03 M_⊙, and an envelope of a similar mass, supporting the suggestion that the object is emerging from its main accretion stage. Molecular, atomic,
and ionic emission lines in the far-infrared reveal the outflow’s influence on the envelope. The inferred hot gas may be photon-heated, but some
emission may be caused by C-shocks in the walls of the outflow cavity
The origin of organic emission in NGC 2071
Context: The physical origin behind organic emission in embedded low-mass
star formation has been fiercely debated in the last two decades. A multitude
of scenarios have been proposed, from a hot corino to PDRs on cavity walls to
shock excitation.
Aims: The aim of this paper is to determine the location and the
corresponding physical conditions of the gas responsible for organics emission
lines. The outflows around the small protocluster NGC 2071 are an ideal testbed
to differentiate between various scenarios.
Methods: Using Herschel-HIFI and the SMA, observations of CH3OH, H2CO and
CH3CN emission lines over a wide range of excitation energies were obtained.
Comparisons to a grid of radiative transfer models provide constraints on the
physical conditions. Comparison to H2O line shape is able to trace gas-phase
synthesis versus a sputtered origin.
Results: Emission of organics originates in three spots: the continuum
sources IRS 1 ('B') and IRS 3 ('A') as well as a outflow position ('F').
Densities are above 10 cm and temperatures between 100 to 200 K.
CH3OH emission observed with HIFI originates in all three regions and cannot be
associated with a single region. Very little organic emission originates
outside of these regions.
Conclusions: Although the three regions are small (<1,500 AU), gas-phase
organics likely originate from sputtering of ices due to outflow activity. The
derived high densities (>10 cm) are likely a requirement for organic
molecules to survive from being destroyed by shock products. The lack of
spatially extended emission confirms that organic molecules cannot (re)form
through gas-phase synthesis, as opposed to H2O, which shows strong line wing
emission. The lack of CH3CN emission at 'F' is evidence for a different history
of ice processing due to the absence of a protostar at that location and recent
ice mantle evaporation.Comment: 10 Pages, 8 figures, Accepted for Astronomy and Astrophysic
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