863 research outputs found
Counting irreducible binomials over finite fields
We consider various counting questions for irreducible binomials over finite
fields. We use various results from analytic number theory to investigate these
questions.Comment: 11 page
On Shifted Eisenstein Polynomials
We study polynomials with integer coefficients which become Eisenstein
polynomials after the additive shift of a variable. We call such polynomials
shifted Eisenstein polynomials. We determine an upper bound on the maximum
shift that is needed given a shifted Eisenstein polynomial and also provide a
lower bound on the density of shifted Eisenstein polynomials, which is strictly
greater than the density of classical Eisenstein polynomials. We also show that
the number of irreducible degree polynomials that are not shifted
Eisenstein polynomials is infinite. We conclude with some numerical results on
the densities of shifted Eisenstein polynomials
On the Number of Eisenstein Polynomials of Bounded Height
We obtain a more precise version of an asymptotic formula of A. Dubickas for
the number of monic Eisenstein polynomials of fixed degree and of height at
most , as . In particular, we give an explicit bound for the
error term. We also obtain an asymptotic formula for arbitrary Eisenstein
polynomials of height at most
Effects of Ray Sediment Disturbance on Meiofauna in Tidal and Intertidal Zones
Feeding pits created by rays may directly or indirectly affect the numbers of meiofauna. We examined the recovery rates of meiofauna inside feeding pits in both intertidal and subtidal areas. Cores were taken inside and immediately outside each pit. Numbers of total meiofauna, nematodes, and other meiofauna found within intertidal pits were significantly reduced following pit formation; the numerically dominant nematodes were reduced by 64%. Recovery to background levels occurred by 48 hours. Numbers of meiofauna in subtidal pits were either unaffected by the feeding activity of rays or differences were undetected due to rapid recovery within 24 h. This is the first study in which comparisons have been made concurrently in adjacent subtidal and intertidal areas
OH rotational lines as a diagnostic of the warm neutral gas in galaxies
We present Infrared Space Observatory (ISO) observations of several OH, CH
and H2O rotational lines toward the bright infrared galaxies NGC253 and
NGC1068. As found in the Galactic clouds in SgrB2 and Orion, the extragalactic
far-IR OH lines change from absorption to emission depending on the physical
conditions and distribution of gas and dust along the line of sight. As a
result, most of the OH rotational lines that appear in absorption toward NGC253
are observed in emission toward NGC1068. We show that the far-IR spectrum of OH
can be used as a powerful diagnostic to derive the physical conditions of
extragalactic neutral gas. In particular, we find that a warm (Tk~150 K, n(H2)<
5 10^4 cm^-3) component of molecular gas with an OH abundance of 10^{-7} from
the inner <15'' can qualitatively reproduce the OH lines toward NGC253. Similar
temperatures but higher densities (5 10^5 cm^-3) are required to explain the OH
emission in NGC1068.Comment: 5 pages, 4 figures, accepted in ApJ Part I (2004, October 6
Extragalactic Zeeman Detections in OH Megamasers
We have measured the Zeeman splitting of OH megamaser emission at 1667 MHz
from five (ultra)luminous infrared galaxies ([U]LIRGs) using the 305 m Arecibo
telescope and the 100 m Green Bank Telescope. Five of eight targeted galaxies
show significant Zeeman-splitting detections, with 14 individual masing
components detected and line-of-sight magnetic field strengths ranging from
~0.5-18 mG. The detected field strengths are similar to those measured in
Galactic OH masers, suggesting that the local process of massive star formation
occurs under similar conditions in (U)LIRGs and the Galaxy, in spite of the
vastly different large-scale environments. Our measured field strengths are
also similar to magnetic field strengths in (U)LIRGs inferred from synchrotron
observations, implying that milligauss magnetic fields likely pervade most
phases of the interstellar medium in (U)LIRGs. These results provide a
promising new tool for probing the astrophysics of distant galaxies.Comment: 32 pages, 14 figures, 8 tables. Accepted for publication in The
Astrophysical Journal v680n2, June 20, 2008; corrected 2 typo
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Offloading devices for the prevention of heel pressure ulcers: a realist evaluation
Background
Heel pressure ulcers can cause pain, reduce mobility, lead to longer hospital stays and in severe cases can lead to sepsis, amputation, and death. Offloading boots are marketed as heel pressure ulcer prevention devices, working by removing pressure to the heel, yet there is little good quality evidence about their clinical effectiveness. Given that evidence is not guiding use of these devices, this study aims to explore, how, when, and why these devices are used in hospital settings.
Objective
To explore how offloading devices are used to prevent heel pressure ulcers, for whom and in what circumstances.
Methods
A realist evaluation was undertaken to explore the contexts, mechanisms, and outcomes that might influence how offloading devices are implemented and used in clinical practice for the prevention of heel pressure ulcers in hospitals. Eight Tissue Viability Nurse Specialists from across the UK (England, Wales, and Northern Ireland) were interviewed. Questions sought to elicit whether, and in what ways, initial theories about the use of heel pressure ulcers fitted with interviewee's experiences.
Results
Thirteen initial theories were refined into three programme theories about how offloading devices are used by nurses ‘proactively’ to prevent heel pressure ulcers, ‘reactively’ to treat and minimise deterioration of early-stage pressure ulcers, and patient factors that influence how these devices are used.
Conclusions
Offloading devices were used in clinical practice by all the interviewees. It was viewed that they were not suitable to be used by every patient, at every point in their inpatient journey, nor was it financially viable. However, the interviewees thought that identifying suitable ‘at risk’ patient groups that can maintain use of the devices could lead to proactive and cost-effective use of the devices.
This understanding of the contexts and mechanisms that influence the effective use of offloading devices has implications for clinical practice and design of clinical trials of offloading devices.
Tweetable abstract
How, for whom, and in what circumstances do offloading devices work to prevent heel pressure ulcers? Tissue viability nurses' perspectives
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