117,623 research outputs found
Gamma-Ray Pulsar Studies with GLAST
Some pulsars have their maximum observable energy output in the gamma-ray
band, offering the possibility of using these high-energy photons as probes of
the particle acceleration and interaction processes in pulsar magnetospheres.
After an extended hiatus between satellite missions, the recently-launched
AGILE mission and the upcoming Gamma-ray Large Area Space Telescope (GLAST)
Large Area Telescope (LAT) will allow gamma-ray tests of the theoretical models
developed based on past discoveries. With its greatly improved sensitivity,
better angular resolution, and larger energy reach than older instruments,
GLAST LAT should detect dozens to hundreds of new gamma-ray pulsars and measure
luminosities, light curves, and phase-resolved spectra with unprecedented
resolution. It will also have the potential to find radio-quiet pulsars like
Geminga, using blind search techniques. Cooperation with radio and X-ray pulsar
astronomers is an important aspect of the LAT team's planning for pulsar
studies.Comment: 8 pages, 5 figures. To appear in the proceedings of "40 Years of
Pulsars: Millisecond Pulsars, Magnetars, and More", August 12-17, 2007,
McGill University, Montreal, Canad
Nondestructive determination of cohesive strength of adhesive-bonded composites
Systematic plan determines vibration responses and modes of honeycomb composites, correlates vibrational responses of composite specimens varying in strength of cohesive bond, determines effects of thickness variation of the face sheet over the frequency range, optimizes the characteristics of the excitation transducer, and measures bond strength
“Altoona was his, and fairly won”: President Lincoln and the Altoona Governors’ Conference, September 1862
This article explores the long-forgotten Altoona Conference of 1862, when nearly a dozen Union governors met at the Civil War\u27s darkest hour to discuss war strategy and, ultimately, reaffirm their support for the Union cause. This article examines and questions the conventional view of the conference as a challenge to President Lincoln\u27s efficacy as the nation\u27s leader. Rather, the article suggests that Lincoln may have actually welcomed the conference and had his own designs for how it might bolster his political objectives
Acute care nurses' perceptions of barriers to using research information in clinical decision-making
Aim. To examine the barriers that nurses feel prevent them from using research in the decisions they make. Background. A sizeable research literature focusing on research utilization in nursing has developed over the past 20 years. However, this literature is characterized by a number of weaknesses: self-reported utilization behaviour; poor response rates and small, nonrandom sampling strategies. Design. Cross-case analysis involving anonymised qualitative interviews, observation, documentary audit and Q methodological modelling of shared subjectivities amongst nurses. The case sites were three large acute hospitals in the north of England. One hundred and eight nurses were interviewed, 61 of whom were also observed for a total of 180 h, and 122 nurses were involved in the Q modelling exercise (response rate of 64%). Results. Four perspectives were isolated that encompassed the characteristics associated with barriers to research use. These related to the individual, organization, nature of research information itself and environment. Nurses clustered around four main perspectives on the barriers to research use: (1) Problems in interpreting and using research products, which were seen as too complex, 'academic' and overly statistical; (2) Nurses who felt confident with research-based information perceived a lack of organizational support as a significant block; (3) Many nurses felt that researchers and research products lack clinical credibility and that they fail to offer the desired level of clinical direction; (4) Some nurses lacked the skills and, to a lesser degree, the motivation to use research themselves. These individuals liked research messages passed on to them by a third party and sought to foster others' involvement in research-based practice, rather than becoming directly involved themselves. Conclusions. Rejection of research knowledge is not a barrier to its application. Rather, the presentation and management of research knowledge in the workplace represent significant challenges for clinicians, policy-makers and the research community
SCUBA observations of the Horsehead Nebula - what did the horse swallow?
We present observations taken with SCUBA on the JCMT of the Horsehead Nebula
in Orion (B33), at wavelengths of 450 and 850 \mum. We see bright emission from
that part of the cloud associated with the photon-dominated region (PDR) at the
`top' of the horse's head, which we label B33-SMM1. We characterise the
physical parameters of the extended dust responsible for this emission, and
find that B33-SMM1 contains a more dense core than was previously suspected. We
compare the SCUBA data with data from the Infrared Space Observatory (ISO) and
find that the emission at 6.75-\mum is offset towards the west, indicating that
the mid-infrared emission is tracing the PDR while the submillimetre emission
comes from the molecular cloud core behind the PDR. We calculate the virial
balance of this core and find that it is not gravitationally bound but is being
confined by the external pressure from the HII region IC434, and that it will
either be destroyed by the ionising radiation, or else may undergo triggered
star formation. Furthermore we find evidence for a lozenge-shaped clump in the
`throat' of the horse, which is not seen in emission at shorter wavelengths. We
label this source B33-SMM2 and find that it is brighter at submillimetre
wavelengths than B33-SMM1. SMM2 is seen in absorption in the 6.75-\mum ISO
data, from which we obtain an independent estimate of the column density in
excellent agreement with that calculated from the submillimetre emission. We
calculate the stability of this core against collapse and find that it is in
approximate gravitational virial equilibrium. This is consistent with it being
a pre-existing core in B33, possibly pre-stellar in nature, but that it may
also eventually undergo collapse under the effects of the HII region.Comment: 11 pages, 6 figures, accepted by MNRA
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