20,097 research outputs found
Faint star counts in the near-infrared
We discuss near-infrared star counts at the Galactic pole with a view to
guiding the NGST and ground-based NIR cameras. Star counts from deep K-band
images from the CFHT are presented, and compared with results from the 2MASS
survey and some Galaxy models. With appropriate corrections for detector
artifacts and galaxies, the data agree with the models down to K~18, but
indicate a larger population of fainter red stars. There is also a significant
population of compact galaxies that extend to the observational faint limit of
K=20.5. Recent Galaxy models agree well down to K19, but diverge at
fainter magnitudes.Comment: 14 pages and 4 diagrams; to appear in PAS
Perfect countably infinite Steiner triple systems
We use a free construction to prove the existence of perfect Steiner triple systems on a countably infinite point set. We use a specific countably infinite family of partial Steiner triple systems to start the construction, thus yielding 2ℵ0 non-isomorphic perfect systems
X-ray sources and their optical counterparts in the globular cluster M 22
Using XMM-Newton EPIC imaging data, we have detected 50 low-luminosity X-ray
sources in the field of view of M 22, where 5 +/- 3 of these sources are likely
to be related to the cluster. Using differential optical photometry, we have
identified probable counterparts to those sources belonging to the cluster.
Using X-ray spectroscopic and timing studies, supported by the optical colours,
we propose that the most central X-ray sources in the cluster are cataclysmic
variables, millisecond pulsars, active binaries and a blue straggler. We also
identify a cluster of galaxies behind this globular cluster.Comment: 11 pages, 7 figures, accepted for publication in A&
Decoherence and Quantum Fluctuations
We show that the zero-point fluctuations of the intrinsic electromagnetic
environment limit the phase coherence time in all mesoscopic systems at low
temperatures. We derive this quantum noise limited dephasing time and its
temperature dependence in the crossover to the thermal regime. Our results
agree well with most experiments in 1D systems.Comment: 4 pages & 1 figur
Observations of QSO J2233-606 in the Southern Hubble Deep Field
The Hubble Deep Field South (HDF-S) HST observations are expected to begin in
October 1998. We present a composite spectrum of the QSO in the HDF-S field
covering UV/optical/near IR wavelengths, obtained by combining data from the
ANU 2.3m Telescope with STIS on the HST. This intermediate resolution spectrum
covers the range 1600-10000A and allows us to derive some basic information on
the intervening absorption systems which will be important in planning future
higher resolution studies of this QSO.Comment: 9 pages and 2 figures, submitted to ApJ
Multiangle static and dynamic light scattering in the intermediate scattering angle range
We describe a light scattering apparatus based on a novel optical scheme
covering the scattering angle range 0.5\dg \le \theta \le 25\dg, an
intermediate regime at the frontier between wide angle and small angle setups
that is difficult to access by existing instruments. Our apparatus uses
standard, readily available optomechanical components. Thanks to the use of a
charge-coupled device detector, both static and dynamic light scattering can be
performed simultaneously at several scattering angles. We demonstrate the
capabilities of our apparatus by measuring the scattering profile of a variety
of samples and the Brownian dynamics of a dilute colloidal suspension
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Bearing witness and being bounded; the experiences of nurses in adult critical care in relation to the survivorship needs of patients and families
Aim: To discern and understand the responses of nurses to the survivorship needs of patients and family members in adult critical care units.
Background: The critical care environment is a demanding place of work which may limit nurses to immediacy of care, such is the proximity to death and the pressure of work.
Design: A constructivist grounded theory approach with constant comparative analysis.
Methods: As part of a wider study and following ethical approval, eleven critical care nurses working within a general adult critical care unit were interviewed with respect to their experiences in meeting the psychosocial needs of patients and family members. Through the process of constant comparative analysis an overarching selective code was constructed. EQUATOR guidelines for qualitative research (COREQ) applied.
Results: The data illuminated a path of developing expertise permitting integration of physical, psychological and family care with technology and humanity. Gaining such proficiency is demanding and the data presented reveals the challenges that nurses experience along the way.
Conclusion: The study confirms that working within a critical care environment is an emotionally charged challenge and may incur an emotional cost. Nurses can find themselves bounded by the walls of the critical care unit and experience personal and professional conflicts in their role. Nurses bear witness to the early stages of the survivorship trajectory but are limited in their support of ongoing needs.
Relevance to Clinical Practice: Critical care nurses can experience personal and professional conflicts when caring for both patients and families. This can lead to moral distress and may contribute to compassion fatigue. Critical care nurses appear bounded to the delivery of physiological and technical care, in the moment, as demanded by the patient's acuity. Consequentially this limits nurses’ ability to support the onward survivorship trajectory. Increased pressure and demands on critical care beds has contributed further to occupational stress in this care setting
Electron dephasing near zero temperature: an experimental review
The behavior of the electron dephasing time near zero temperature,
, has recently attracted vigorous attention. This renewed interest
is primarily concerned with whether should reach a finite or an
infinite value as 0. While it is accepted that should
diverge if there exists only electron-electron (electron-phonon) scattering,
several recent measurements have found that depends only very
weakly on temperature, if at all, when is sufficiently low. This article
discusses the current experimental status of "the saturation problem", and
concludes that the origin(s) for this widely observed saturation are still
unresolved
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