227 research outputs found
Engineering magnetic domain-wall structure in permalloy nanowires
Using Lorentz transmission electron microscopy we investigate the behavior of
domain walls pinned at non-topographic defects in Cr(3 nm)/Permalloy(10
nm)/Cr(5 nm) nanowires of width 500 nm. The pinning sites consist of linear
defects where magnetic properties are modified by a Ga ion probe with diameter
~ 10 nm using a focused ion beam microscope. We study the detailed change of
the modified region (which is on the scale of the focused ion spot) using
electron energy loss spectroscopy and differential phase contrast imaging on an
aberration (Cs) corrected scanning transmission electron microscope. The signal
variation observed indicates that the region modified by the irradiation
corresponds to ~ 40-50 nm despite the ion probe size of only 10 nm. Employing
the Fresnel mode of Lorentz transmission electron microscopy, we show that it
is possible to control the domain wall structure and its depinning strength not
only via the irradiation dose but also the line orientation.Comment: Accepted for publication in Physical Review Applie
Application of monoclonal antibodies in quantifying fungal growth dynamics during aerobic spoilage of silage
Proliferation of filamentous fungi following ingress of oxygen to silage is an important cause of dry matter losses, resulting in significant waste. In addition, the production of mycotoxins by some filamentous fungi pose a risk to animal health through mycotoxicosis. Quantitative assessment of fungal growth in silage, through measurement of ergosterol content, colony forming units or temperature increase are limiting in representing fungal growth dynamics during aerobic spoilage due to being deficient in either representing fungal biomass or being able to identify specific genera. Here, we conducted a controlled environment aerobic exposure experiment to test the efficacy of a monoclonal antibody-based enzyme linked immunosorbent assay (ELISA) to detect the proliferation of fungal biomass in six silage samples. We compared this to temperature which has been traditionally deployed in such experiments and on-farm to detect aerobic deterioration. In addition, we quantified ergosterol, a second marker of fungal biomass. At 8 d post aerobic exposure, the ergosterol and ELISA methods indicated an increase in fungal biomass in one of the samples with a temperature increase observed after 16 d. A comparison of the methods with Pearson’s correlation coefficient showed a positive association between temperature and ergosterol and both markers of fungal biomass. This work indicates that the technology has potential to be used as an indicator of microbial degradation in preserved forage. Consequently, if developed as an on farm technique this could inform forage management decisions made by farmers, with the goal of decreasing dry matter losses, improving resource and nutrient efficiency and reducing risks to animal health
Rapid ex-ante environmental impact assessment of livestock intensification strategies on mixed crop-livestock and agro-pastoralist farmers in Tanga region, Tanzania
The Ammount of Interstellar Carbon Locked in Solid Hydrogenated Amorphous Carbon
We review the literature and present new experimental data to determine the
amount of carbon likely to be locked in form of solid hydrogenated amorphous
carbon (HAC) grains. We conclude on the basis of a thorough analysis of the
intrinsic strength of the C-H stretching band at 3.4 micron that between 10 and
80 ppM H of carbon is in the form of HAC grains. We show that it is necessary
to know the level of hydrogenation (H/C) of the interstellar HAC to determine
more precisely the amount of carbon it ties up. We present optical constants,
photoluminescence spectroscopy, and IR absorption spectroscopy for a particular
HAC sample that is shown to have a 3.4 micron absorption feature that is
quantatively consistent with that observed in the diffuse interstellar medium.Comment: This paper is 14 pages long with 5 figures and will appear in the 1
December 1999 issue of Ap
Hydrocarbon Dust Absorption in Seyfert Galaxies and ULIRGs
We present new spectroscopic observations of the 3.4 micron absorption
feature in the Seyfert galaxies, NGC1068 and NGC7674, and the ultraluminous
infrared galaxy, IRAS08572+3915. A signature of C-H bonds in aliphatic
hydrocarbons, the 3.4 micron feature indicates the presence of organic material
in Galactic and extragalactic dust. Here we compare the 3.4 micron feature in
all the galaxies in which it has been detected. In several cases, the
signal-to-noise ratio and spectral resolution permit a detailed examination of
the feature profile, something which has rarely been attempted in extragalactic
lines of sight. The 3.4 micron band in these galaxies closely resembles that
seen in the Galactic diffuse ISM and in newly-formed dust in a protoplanetary
nebula. The similarity implies a common carrier for the carbonaceous component
of dust, and one which is resistant to processing in the interstellar and/or
circumnuclear medium. We also examine the mid-IR spectrum of NGC1068, because
absorption bands in the 5-8 micron region further constrain the chemistry of
the 3.4 micron band carrier. While weak features like those present in the
mid-IR spectrum of diffuse dust towards the Galactic center would be
undetectable in NGC1068, the strong bands found in the spectra of many proposed
dust analog materials are clearly absent, eliminating certain candidates and
production mechanisms for the carrier. The absence of strong absorption
features at 5-8 microns is also consistent with the interpretation that the
similarity in the 3.4 micron feature in NGC1068 to that in Galactic lines of
sight reflects real chemical similarity in the carbonaceous dust.Comment: 30 pages, 8 figures (preprint style), ApJ accepte
M-Band Spectra of Dust Embedded Sources at the Galactic Center
The goal of the present paper is to investigate the circumstellar material
around the brightest dust-enshrouded sources in the central stellar cluster of
the Milky Way. Observations have been carried out at the European Southern
Observatory's Very Large Telescope on Paranal, Chile. We have used the long
wavelength (LWS3) low resolution (LR) spectroscopic mode of the ISAAC camera at
the VLT in the spectral range of the M filter from 4.4micron to 5.1micron. The
use of a slit width of 0.6" implied a spectral resolution of R=l/Dl=800 (Dv=375
km/s). These observations resulted in M-band spectra of 15 bright sources in
the central stellar cluster of the Milky Way. In addition to gaseous 12^CO
(4.666 micron) and 13^CO (4.77 micron) vibration-rotational absorptions, we
detect a strong absorption due to a mixture of polar and apolar CO ice
(centered at 4.675 micron). In the shorter wavelength absorption wing there is
an absorption feature due to XCN at 4.62 micron. The XCN absorption is
strongest toward the M2 supergiant IRS7. We find that the extinctions due to
material traced by the CO ice and the CO gas absorptions may be of comparable
importance. Using the spectra of IRS2L and IRS16C we perform a first order
correction of the line of sight absorption due to CO-ice and 13^CO gas. In
combination with published hydrogen number density estimates from sub-mm
CO(7-6) and FIR [OI] line data we obtain gas masses of the circumstellar shells
of the order of 10^-3 and 10^-2 solar masses. This implies that in future
spectra taken at high spectral and angular resolution the bright and dust
embedded Galactic Center sources should show a substantial line absorption due
to source intrinsic absorption.Comment: 23 pages, 9 figures, Accepted for publication in Ap
Realist analysis of whether emergency departments with primary care services generate ‘provider-induced demand’
Background: It is not known whether emergency departments (EDs) with primary care services influence demand for non-urgent care (‘provider-induced demand’). We proposed that distinct primary care services in EDs encourages primary care demand, whereas primary care integrated within EDs may be less likely to cause additional demand. We aimed to explore this and explain contexts (C), mechanisms (M) and outcomes (O) influencing demand.
Methods: We used realist evaluation methodology and observed ED service delivery. Twenty-four patients and 106 staff members (including Clinical Directors and General Practitioners) were interviewed at 13 EDs in England and Wales (240 hours of observations across 30 days). Field notes from observations and interviews were analysed by
creating ‘CMO’ configurations to develop and refine theories relating to drivers of demand.
Results: EDs with distinct primary care services were perceived to attract demand for primary care because services were visible, known or enabled direct access to health care services. Other influencing factors included patients’ experiences of accessing primary care, community care capacity, service design and population characteristics.
Conclusions: Patient, local-system and wider-system factors can contribute to additional demand at EDs that include primary care services. Our findings can inform service providers and policymakers in developing strategies to limit the effect of potential influences on additional demand when demand exceeds capacity
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