1,116 research outputs found
Resilience markers for safer systems and organisations
If computer systems are to be designed to foster resilient
performance it is important to be able to identify contributors to resilience. The
emerging practice of Resilience Engineering has identified that people are still a
primary source of resilience, and that the design of distributed systems should
provide ways of helping people and organisations to cope with complexity.
Although resilience has been identified as a desired property, researchers and
practitioners do not have a clear understanding of what manifestations of
resilience look like. This paper discusses some examples of strategies that
people can adopt that improve the resilience of a system. Critically, analysis
reveals that the generation of these strategies is only possible if the system
facilitates them. As an example, this paper discusses practices, such as
reflection, that are known to encourage resilient behavior in people. Reflection
allows systems to better prepare for oncoming demands. We show that
contributors to the practice of reflection manifest themselves at different levels
of abstraction: from individual strategies to practices in, for example, control
room environments. The analysis of interaction at these levels enables resilient
properties of a system to be âseenâ, so that systems can be designed to explicitly
support them. We then present an analysis of resilience at an organisational
level within the nuclear domain. This highlights some of the challenges facing
the Resilience Engineering approach and the need for using a collective
language to articulate knowledge of resilient practices across domains
A Correlation Between Hard Gamma-ray Sources and Cosmic Voids Along the Line of Sight
We estimate the galaxy density along lines of sight to hard extragalactic
gamma-ray sources by correlating source positions on the sky with a void
catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray
sources that are detected at very high energy (VHE; E>100 GeV) or have been
highlighted as VHE-emitting candidates in the Fermi Large Area Telescope hard
source catalog (together referred to as "VHE-like" sources) are distributed
along underdense lines of sight at the 2.4 sigma level. There is also a less
suggestive correlation for the Fermi hard source population (1.7 sigma). A
correlation between 10-500 GeV flux and underdense fraction along the line of
sight for VHE-like and Fermi hard sources is found at 2.4 sigma and 2.6 sigma,
respectively. The preference for underdense sight lines is not displayed by
gamma-ray emitting galaxies within the second Fermi catalog, containing sources
detected above 100 MeV, or the SDSS DR7 quasar catalog. We investigate whether
this marginal correlation might be a result of lower extragalactic background
light (EBL) photon density within the underdense regions and find that, even in
the most extreme case of a entirely underdense sight line, the EBL photon
density is only 2% less than the nominal EBL density. Translating this into
gamma-ray attenuation along the line of sight for a highly attenuated source
with opacity tau(E,z) ~5, we estimate that the attentuation of gamma-rays
decreases no more than 10%. This decrease, although non-neglible, is unable to
account for the apparent hard source correlation with underdense lines of
sight.Comment: Accepted by MNRA
A study of the relative effectiveness and cost of computerized information retrieval in the interactive mode
Results of a number of experiments to illuminate the relative effectiveness and costs of computerized information retrieval in the interactive mode are reported. It was found that for equal time spent in preparing the search strategy, the batch and interactive modes gave approximately equal recall and relevance. The interactive mode however encourages the searcher to devote more time to the task and therefore usually yields improved output. Engineering costs as a result are higher in this mode. Estimates of associated hardware costs also indicate that operation in this mode is more expensive. Skilled RECON users like the rapid feedback and additional features offered by this mode if they are not constrained by considerations of cost
Absolute calibration and beam reconstruction of MITO (a ground-based instrument in the millimetric region)
An efficient sky data reconstruction derives from a precise characterization
of the observing instrument. Here we describe the reconstruction of
performances of a single-pixel 4-band photometer installed at MITO (Millimeter
and Infrared Testagrigia Observatory) focal plane. The strategy of differential
sky observations at millimeter wavelengths, by scanning the field of view at
constant elevation wobbling the subreflector, induces a good knowledge of beam
profile and beam-throw amplitude, allowing efficient data recovery. The
problems that arise estimating the detectors throughput by drift scanning on
planets are shown. Atmospheric transmission, monitored by skydip technique, is
considered for deriving final responsivities for the 4 channels using planets
as primary calibrators.Comment: 14 pages, 6 fiugres, accepted for pubblication by New Astronomy (25
March
Opportunities and barriers for adoption of a decision-support tool for Alzheimer's Disease
Clinical decision-support tools (DSTs) represent a valuable resource in healthcare. However, lack of Human
Factors considerations and early design research has often limited their successful adoption. To complement
previous technically focused work, we studied adoption opportunities of a future DST built on a predictive
model of Alzheimerâs Disease (AD) progression. Our aim is two-fold: exploring adoption opportunities for
DSTs in AD clinical care, and testing a novel combination of methods to support this process. We focused
on understanding current clinical needs and practices, and the potential for such a tool to be integrated
into the setting, prior to its development. Our user-centred approach was based on field observations and
semi-structured interviews, analysed through workflow analysis, user profiles, and a design-reality gap model.
The first two are common practice, whilst the latter provided added value in highlighting specific adoption
needs. We identified the likely early adopters of the tool as being both psychiatrists and neurologists based in
research-oriented clinical settings. We defined ten key requirements for the translation and adoption of DSTs
for AD around IT, user, and contextual factors. Future works can use and build on these requirements to stand
a greater chance to get adopted in the clinical setting
James Huttonâs geological tours of Scotland : romanticism, literary strategies, and the scientific quest
This article explores a somewhat neglected part of the story of the emergence of geology as a science and discourse in the late eighteenth century â James Huttonâs posthumously published accounts of the geological tours of Scotland that he undertook in the years 1785 to 1788 in search of empirical evidence in support of his theory of the Earth and that he intended to include in the projected third volume of his Theory of the Earth of 1795. The article brings some of the assumptions and techniques of literary criticism to bear on Huttonâs scientific travel writing in order to open up new connections between geology, Romantic aesthetics and eighteenth-century travel writing about Scotland. Close analysis of Huttonâs accounts of his field trips to Glen Tilt, Galloway and Arran, supplemented by later accounts of the discoveries at Jedburgh and Siccar Point, reveals the interplay between desire, travel and the scientific quest and foregrounds the textual strategies that Hutton uses to persuade his readers that they share in the experience of geological discovery and interpretation as âvirtual witnessesâ. As well as allowing us to revisit the interrelation between scientific theory and discovery, this article concludes that Hutton was a much better writer than he has been given credit for and suggests that if these geological tours had been published in 1795 they would have made it impossible for critics to dismiss him as an armchair geologist
Genetic screening of 202 individuals with congenital limb malformations and requiring reconstructive surgery
BACKGROUND: Congenital limb malformations (CLMs) are common and present to a variety of specialties, notably plastic and orthopaedic surgeons, and clinical geneticists. The authors aimed to characterise causative mutations in an unselected cohort of patients with CLMs requiring reconstructive surgery. METHODS: 202 patients presenting with CLM were recruited. The authors obtained G-banded karyotypes and screened EN1, GLI3, HAND2, HOXD13, ROR2, SALL1, SALL4, ZRS of SHH, SPRY4, TBX5, TWIST1 and WNT7A for point mutations using denaturing high performance liquid chromatography (DHPLC) and direct sequencing. Multiplex ligation dependent probe amplification (MLPA) kits were developed and used to measure copy number in GLI3, HOXD13, ROR2, SALL1, SALL4, TBX5 and the ZRS of SHH. RESULTS: Within the cohort, causative genetic alterations were identified in 23 patients (11%): mutations in GLI3 (n = 5), HOXD13 (n = 5), the ZRS of SHH (n = 4), and chromosome abnormalities (n = 4) were the most common lesions found. Clinical features that predicted the discovery of a genetic cause included a bilateral malformation, positive family history, and having increasing numbers of limbs affected (all p<0.01). Additionally, specific patterns of malformation predicted mutations in specific genes. CONCLUSIONS: Based on higher mutation prevalence the authors propose that GLI3, HOXD13 and the ZRS of SHH should be prioritised for introduction into molecular genetic testing programmes for CLM. The authors have developed simple criteria that can refine the selection of patients by surgeons for referral to clinical geneticists. The cohort also represents an excellent resource to test for mutations in novel candidate genes
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Detection of [O I] 63 <i>Ό</i>m in absorption toward Sgr B2
A high signal-to-noise 52-90 ÎŒm spectrum is presented for the central part of the Sagittarius B2 complex. The data were obtained with the Long Wavelength Spectrometer on board the Infrared Space Observatory (ISO). The [O I] 63 ÎŒm line is detected in absorption even at the grating spectral resolution of 0.29 ÎŒm. A lower limit for the column density of atomic oxygen of the order of 1019 cm-2 is derived. This implies that more than 40% of the interstellar oxygen must be in atomic form along the line of sight toward the Sgr B2 molecular cloud
Shrub Communities, Spatial Patterns, and Shrub-Mediated Tree Mortality following Reintroduced Fire in Yosemite National Park, California, USA
Shrubs contribute to the forest fuel load; their distribution is important to tree mortality and regeneration, and vertebrate occupancy. We used a method new to fire ecologyâextensive continuous mapping of trees and shrub patches within a single large (25.6 ha) study siteâto identify changes in shrub area, biomass, and spatial pattern due to fire reintroduction by a backfire following a century of fire exclusion in lower montane forests of the Sierra Nevada, California, USA. We examined whether trees in close proximity to shrubs prior to fire experienced higher mortality rates than trees in areas without shrubs. We calculated shrub biomass using demography subplots and existing allometric equations, and we developed new equations for beaked hazel (Corylus cornuta ssp. californica [A. de Candolle] E. Murray) from full dissection of 50 stems. Fire decreased shrub patch area from 15.1 % to 0.9 %, reduced live shrub biomass from 3.49 Mg haâ1 to 0.27 Mg haâ1, and consumed 4.41 Mg haâ1 of living and dead shrubs. Distinct (non-overlapping) shrub patches decreased from 47 haâ1 to 6 haâ1. The mean distance between shrub patches increased 135 %. Distances between montane chaparral patches increased 285 %, compared to a 54 % increase in distances between riparian shrub patches and an increase of 267 % between generalist shrub patches. Fire-related tree mortality within shrub patches was marginally lower (67.6 % versus 71.8 %), showing a contrasting effect of shrubs on tree mortality between this forest ecosystem and chaparral-dominated ecosystems in which most trees are killed by fire
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