1,150 research outputs found
Identification of climatological sub-regions within the Tully mill area
Identifying optimal nitrogen application rates that reduce nitrogen loss without adversely reducing yields would benefit growers and the environment. In order to identify optimal nitrogen application rates throughout the Tully mill area, it is important to identify sub-regions that share similar topographical, soil, farm management, productivity or climatological attributes. While current SIX EASY STEPS nitrogen guidelines enable a hierarchy of district, soil, block and crop nitrogen requirements for sugarcane, it would be beneficial for management zones to also take spatial climate variability information into account. Unfortunately, spatial climate variability within a region, is generally not considered when developing nitrogen management practices. The objective of this paper was to identify sub-regions within the Tully mill area based on climatological attributes as a first step towards better informing nitrogen management decisions. Rainfall, radiation and temperature data were obtained on a 0.05 by 0.05Ë grid (approximately 5 km by 5 km) for sugarcane-growing areas within the Tully Mill region. A K-means clustering algorithm was then used to cluster these grid cells into distinct sub-regions based on seasonal or annual climate data. Two distinct sub-regions were identified based on total annual rainfall and annual average daily radiation data. These sub-regions were identified as a northern and southern sub-region, divided roughly along the Tully River. The northern sub-region was characterised by lower radiation, lower temperatures and higher rainfall than the southern sub-region. Crop simulation models will now be able to use this knowledge to assess if nitrogen management plans should vary between the two sub-regions in Tully
Unusually Weak Diffuse Interstellar Bands toward HD 62542
As part of an extensive survey of diffuse interstellar bands (DIBs), we have
obtained optical spectra of the moderately reddened B5V star HD 62542, which is
known to have an unusual UV extinction curve of the type usually identified
with dark clouds. The typically strongest of the commonly catalogued DIBs
covered by the spectra -- those at 5780, 5797, 6270, 6284, and 6614 A -- are
essentially absent in this line of sight, in marked contrast with other lines
of sight of similar reddening. We compare the HD 62542 line of sight with
others exhibiting a range of extinction properties and molecular abundances and
interpret the weakness of the DIBs as an extreme case of deficient DIB
formation in a dense cloud whose more diffuse outer layers have been stripped
away. We comment on the challenges these observations pose for identifying the
carriers of the diffuse bands.Comment: 20 pages, 4 figures; aastex; accepted by Ap
The Los Alamos Trapped Ion Quantum Computer Experiment
The development and theory of an experiment to investigate quantum
computation with trapped calcium ions is described. The ion trap, laser and ion
requirements are determined, and the parameters required for quantum logic
operations as well as simple quantum factoring are described.Comment: 41 pages, 16 figures, submitted to Fortschritte der Physi
VLT/UVES Observations of Interstellar Molecules and Diffuse Bands in the Magellanic Clouds
We discuss the abundances of interstellar CH, CH+, and CN in the Magellanic
Clouds (MC), derived from spectra of 7 SMC and 13 LMC stars obtained (mostly)
with the VLT/UVES. CH and/or CH+ are detected toward 3 SMC and 9 LMC stars; CN
is detected toward 2 stars. In the MC, the CH/H2 ratio is comparable to that
found for diffuse Galactic molecular clouds in some sight lines, but is lower
by factors up to 10-15 in others. The abundance of CH in the MC thus appears to
depend on local physical conditions -- and not just on metallicity. The
observed relationships between the column density of CH and those of CN, CH+,
Na I, and K I in the MC are generally consistent with the trends observed in
our Galaxy. Using existing data for the rotational populations of H2, we
estimate temperatures, radiation field strengths, and local hydrogen densities
for the diffuse molecular gas. Densities estimated from N(CH), assuming that CH
is produced via steady-state gas-phase reactions, are considerably higher; much
better agreement is found by assuming that the CH is made via the (still
undetermined) process(es) responsible for the observed CH+. The UVES spectra
also reveal absorption from the diffuse interstellar bands at 5780, 5797, and
6284 A in the MC. On average, the three DIBs are weaker by factors of 7-9 (LMC)
and about 20 (SMC), compared to those observed in Galactic sight lines with
similar N(H I), and by factors of order 2-6, relative to E(B-V), N(Na I), and
N(K I). The detection of several of the ``C2 DIBs'', with strengths similar to
those in comparable Galactic sight lines, however, indicates that no single,
uniform scaling factor (e.g., one related to metallicity) applies to all DIBs
(or all sight lines) in the MC. (abstract abridged)Comment: 59 pages, 15 figures, 10 tables; aastex; accepted to ApJ
Identification of HCCC as a diffuse interstellar band carrier
We present strong evidence that the broad, diffuse interstellar bands (DIBs)
at 4881 and 5450\,\AA are caused by the
B\,^1B\,\,X\,^1A transition of HCCC (l-CH).
The large widths of the bands are due to the short lifetime of the B\,^1B
electronic state. The bands are predicted from absorption measurements in a
neon matrix and observed by cavity ring-down in the gas phase and show exact
matches to the profiles and wavelengths of the two broad DIBs. The strength of
the 5450\,\AA DIB leads to a l-CH column density of
cm towards HD\,183143 and
\,cm to HD\,206267. Despite similar values of
(), the 4881 and 5450\,\AA DIBs in HD\,204827 are less than one third
their strength in HD\,183143, while the column density of interstellar C is
unusually high for HD\,204827 but undetectable for HD\,183143. This can be
understood if C has been depleted by hydrogenation to species such as
l-CH towards HD\,183143. There are also three rotationally resolved
sets of triplets of l-CH in the 61506330\,\AA region. Simulations,
based on the derived spectroscopic constants and convolved with the expected
instrumental and interstellar line broadening, show credible coincidences with
sharp, weak DIBs for the two observable sets of triplets. The region of the
third set is too obscured by the -band of telluric O.Comment: 22 pages, 9 figure
Do screening tools assess palliative care needs and 12-month mortality in patients admitted to hepatology in-patient wards?
BACKGROUND: Many liver patients have unmet palliative care needs, but liver clinicians are unclear whom to refer to specialist palliative care (SPC). The Supportive and Palliative Care Indicator Tool (SPICT) and the Bristol Prognostic Screening Tool (BPST) could help identify suitable patients, but neither has been tested for this role. This study evaluated their role as screening tools for palliative care needs and for predicting 12-month mortality. METHODS: A case note review of hepatology in-patients, who were not peritransplant and post-transplant status, was conducted in one tertiary unit. Main outcomes were clinical judgement of need for SPC referral, BPST scores, SPICT attribution of caseness and 12-month survival status. Discriminatory ability of tools was assessed using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and area under the receiver operating characteristic (AUROC) curve. RESULTS: 117 medical notes were reviewed for survival analysis, 47 of which were additionally assessed for suitability for SPC referral, using clinical judgement. SPICT (sensitivity=93%; PPV=93%; AUROC=0.933) and BPST (sensitivity=59%, PPV=79%, AUROC=0.693) demonstrated excellent and good performance, respectively, in predicting patientsâ need for SPC referral. SPICT and BPST only had moderate ability at predicting death at 12 months (PPV: 54% and 56%, respectively). CONCLUSION: SPICT and BPST show potential as screening tools for identifying patients for referral to SPC. Further work is needed to determine how to implement these tools in a clinical setting
BBN and the Primordial Abundances
The relic abundances of the light elements synthesized during the first few
minutes of the evolution of the Universe provide unique probes of cosmology and
the building blocks for stellar and galactic chemical evolution, while also
enabling constraints on the baryon (nucleon) density and on models of particle
physics beyond the standard model. Recent WMAP analyses of the CBR temperature
fluctuation spectrum, combined with other, relevant, observational data, has
yielded very tight constraints on the baryon density, permitting a detailed,
quantitative confrontation of the predictions of Big Bang Nucleosynthesis with
the post-BBN abundances inferred from observational data. The current status of
this comparison is presented, with an emphasis on the challenges to astronomy,
astrophysics, particle physics, and cosmology it identifies.Comment: To appear in the Proceedings of the ESO/Arcetri Workshop on "Chemical
Abundances and Mixing in Stars in the Milky Way and its Satellites", eds., L.
Pasquini and S. Randich (Springer-Verlag Series, "ESO Astrophysics Symposia"
Early-universe constraints on a time-varying fine structure constant
Higher-dimensional theories have the remarkable feature of predicting a time
(and hence redshift) dependence of the `fundamental' four dimensional constants
on cosmological timescales. In this paper we update the bounds on a possible
variation of the fine structure constant alpha at the time of BBN (z =10^10)
and CMB (z=10^3). Using the recently-released high-resolution CMB anisotropy
data and the latest estimates of primordial abundances of 4He and D, we do not
find evidence for a varying alpha at more than one-sigma level at either epoch.Comment: 5 pages, 1 figure, minor misprints corrected, references added. The
analysis has been updated using new BOOMERanG and DASI data on CMB anisotrop
- âŠ