140 research outputs found
The Physical Characteristics of the Small-Scale Interstellar Structure towards Mu Crucis
We present HST/GHRS echelle observations of multiple interstellar lines of
CI, MgI, CrII, and ZnII towards both stars in the mu Cru binary system. Despite
large differences in the profiles of the neutral species, no significant
variations between the stars are seen in the CrII and ZnII line profiles. In
particular, the ZnII absorption observed at -8.6 km/sec towards mu Cru is
constant despite greatly enhanced columns of the neutral species at this
velocity towards mu^1 Cru. An analysis of the fine-structure excitation of CI
in this cloud implies that the density is n_H < 250 cm^{-3}. From the lack of
variation in the (optical) NaI D2 line profiles towards mu^1 and mu^2 Cru in
spectra taken 21 months apart, we can place a lower limit to the size of the
structures of ~10 AU. These results are discussed in the context of recent
radio and optical studies of apparently pervasive high density small-scale
interstellar structure.Comment: 10 pages, 2 figures, to appear in the Astrophysical Journal (Letters
Reconstruction of cumulative daylight illumination fields from high dynamic range imaging: Theory, deployment and in-situ validation
A novel high-dynamic range (HDR) camera-based approach to measure the cumulative daylight dose in historic/conservation spaces has been devised and tested in a real-world setting under normal viewing conditions. The technique derives illuminance from the HDR-acquired luminance at numerous patches of the wall surfaces visible in the HDR image. These patches serve as proxy illuminance meters, thereby allowing the prevailing illumination field across the entire visible wall to be derived using a Kriging algorithm. The technique was validated under both controlled and in-situ conditions over periods of several months and shown to have comparable accuracy to the illuminance logging devices commonly used in historic/conservation settings. The set-up comprising a consumer digital camera and tethered computer proved remarkably resilient and allowed for continuous monitoring periods of six months or more. Application in a real-world setting revealed operational practicalities that would not have been found in a controlled environment.</div
New tools for managing daylight exposure of works of art: case study of Hambletonian, Mount Stewart, Northern Ireland
This paper describes a project to reduce the excessive daylight exposure
of an oil painting, Hambletonian, Rubbing Down, displayed at Mount Stewart,
Northern Ireland. Climate-based daylight modelling (CBDM) was used to understand
the light exposure of Hambletonian and to assess the impact of control measures on
the annual light exposure and viewing condition of the painting in the winter months.
The computer model was used in conjunction with measured lux data to establish
the base case light exposure and the effect of the control measures. Light control
was implemented through the use of darker paint finishes on the walls and ceiling,
which reduced the amount of reflected light reaching Hambletonian;; and the addition
of a mesh screen to the outside of the glazed dome above the painting. These
interventions were cost-effective and straightforward to implement and manage.
CBDM suggests the interventions reduced Hambletonian’s annual daylight exposure from 3.5 mlxhr to 0.63 mlxhr
Illumination and conservation: a case study evaluation of daylight exposure for an artwork displayed in an historic building
This paper describes the application of climate-based daylight modelling to predict the annual daylight exposure received by an 18th century painting oil displayed on the Stone Staircase at Mount Stewart, near Belfast, Northern Ireland. The simulation predicted that the painting was receiving several times the recommended daylight exposure limit of 0.6 Mlux hrs for this type of artefact. The predictions were compared against the limited monitored data that were taken at the site. Notwithstanding the shortcomings of the monitored data, the agreement with simulation was sufficiently encouraging to allow recommendations to be made regarding interventions to help reduce the daylight exposure experienced by the painting
New developments in understanding daylight exposure in heritage interiors
This paper reports on an investigation into daylight exposure in National Trust (England,
Wales and Northern Ireland) interiors. Developing a study of a top lit staircase at Mount Stewart, the focus of this research is the daylight performance of side lit rooms. The multistrand methodology involved: conventional use of light data loggers with a novel camera system based on high dynamic range (HDR) imaging; simulation using climate based daylight modelling (CBDM); and detailed recording of room use by staff. Although
integrating this data has proved challenging, early results from both the simulation and the HDR system already provide insights into collections management practises for Trust staff
Metabolic molecular markers of the tidal clock in the marine crustacean Eurydice pulchra
SummaryIn contrast to the well mapped molecular orchestration of circadian timekeeping in terrestrial organisms, the mechanisms that direct tidal and lunar rhythms in marine species are entirely unknown. Using a combination of biochemical and molecular approaches we have identified a series of metabolic markers of the tidal clock of the intertidal isopod Eurydice pulchra. Specifically, we show that the overoxidation of peroxiredoxin (PRX), a conserved marker of circadian timekeeping in terrestrial eukaryotes [1], follows a circatidal (approximately 12.4 hours) pattern in E. pulchra, in register with the tidal pattern of swimming. In parallel, we show that mitochondrially encoded genes are expressed with a circatidal rhythm. Together, these findings demonstrate that PRX overoxidation rhythms are not intrinsically circadian; rather they appear to resonate with the dominant metabolic cycle of an organism, regardless of its frequency. Moreover, they provide the first molecular leads for dissecting the tidal clockwork
Search for Interstellar Water in the Translucent Molecular Cloud toward HD 154368
We report an upper limit of 9 x 10^{12} cm-2 on the column density of water
in the translucent cloud along the line of sight toward HD 154368. This result
is based upon a search for the C-X band of water near 1240 \AA carried out
using the Goddard High Resolution Spectrograph of the Hubble Space Telescope.
Our observational limit on the water abundance together with detailed chemical
models of translucent clouds and previous measurements of OH along the line of
sight constrain the branching ratio in the dissociative recombination of H_3O+
to form water. We find at the level that no more than 30% of
dissociative recombinations of H_3O+ can lead to H_2O. The observed spectrum
also yielded high-resolution observations of the Mg II doublet at 1239.9 \AA
and 1240.4 \AA, allowing the velocity structure of the dominant ionization
state of magnesium to be studied along the line of sight. The Mg II spectrum is
consistent with GHRS observations at lower spectral resolution that were
obtained previously but allow an additional velocity component to be
identified.Comment: Accepted by ApJ, uses aasp
High Throughput Discovery of Lightweight Corrosion-Resistant Compositionally Complex Alloys
Compositionally complex alloys hold the promise of simultaneously attaining
superior combinations of properties such as corrosion resistance,
light-weighting, and strength. Achieving this goal is a challenge due in part
to a large number of possible compositions and structures in the vast alloy
design space. High throughput methods offer a path forward, but a strong
connection between the synthesis of a given composition and structure with its
properties has not been fully realized to date. Here we present the rapid
identification of light weight highly corrosion-resistant alloys based on
combinations of Al and Cr in a Cantor-like base alloy (Al-Co-Cr-Fe-Ni).
Previously unstudied alloy stoichiometries were identified using a combination
of high throughput experimental screening coupled with key metallurgical and
electrochemical corrosion tests, identifying alloys with excellent passivation
behavior. Importantly, the electrochemical impedance modulus of the
exposure-modified, air-formed film at the corrosion potential was found as an
accurate non-destructive predictor of corrosion and passivation
characteristics. Multi-element EXAFS analyses connected more ordered type
chemical short range order in the Ni-Al 1st nn shell to poorer corrosion. This
report underscores the utility of high throughput exploration of
compositionally complex alloys for the identification and rapid screening of
vast stoichiometric space
Early rheumatoid arthritis is characterized by a distinct and transient synovial fluid cytokine profile of T cell and stromal cell origin
Pathological processes involved in the initiation of rheumatoid synovitis remain unclear. We undertook the present study to identify immune and stromal processes that are present soon after the clinical onset of rheumatoid arthritis ( RA) by assessing a panel of T cell, macrophage, and stromal cell related cytokines and chemokines in the synovial fluid of patients with early synovitis. Synovial fluid was aspirated from inflamed joints of patients with inflammatory arthritis of duration 3 months or less, whose outcomes were subsequently determined by follow up. For comparison, synovial fluid was aspirated from patients with acute crystal arthritis, established RA and osteoarthritis. Rheumatoid factor activity was blocked in the synovial fluid samples, and a panel of 23 cytokines and chemokines measured using a multiplex based system. Patients with early inflammatory arthritis who subsequently developed RA had a distinct but transient synovial fluid cytokine profile. The levels of a range of T cell, macrophage and stromal cell related cytokines ( e. g. IL-2, IL-4, IL-13, IL-17, IL-15, basic fibroblast growth factor and epidermal growth factor) were significantly elevated in these patients within 3 months after symptom onset, as compared with early arthritis patients who did not develop RA. In addition, this profile was no longer present in established RA. In contrast, patients with non-rheumatoid persistent synovitis exhibited elevated levels of interferon-gamma at initiation. Early synovitis destined to develop into RA is thus characterized by a distinct and transient synovial fluid cytokine profile. The cytokines present in the early rheumatoid lesion suggest that this response is likely to influence the microenvironment required for persistent RA
Pressed for Space: The Effects of Justification and the Printing Process on Fifteenth-Century Orthography
There is a long-held belief that, prior to the standardisation of written English, printers altered spellings to justify their type. I investigate this claim through an analysis of spelling changes in William Caxton’s two editions of the Canterbury Tales—by examining text within one book, written by one author, and set by one compositor, the only difference between the sections of verse and the sections of prose should be the requirement for justification within the latter. Were the compositors altering spellings to justify their type, we would expect to see a greater number of altered spellings in the prose sections of text. This is not what the results of this study show—instead there is no statistically significant difference between the frequency of spelling changes in justified and non-justified text. However, there is a significantly higher number of abbreviations introduced into the justified text. These results suggest that the compositor of Caxton’s second edition Canterbury Tales did not change spellings to justify his type
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