1,611 research outputs found
Improvement of oxygen partial pressure sensor
Flight type calcium stabilized solid electrolyte oxygen senso
Distributional Modes for Scalar Field Quantization
We propose a mode-sum formalism for the quantization of the scalar field
based on distributional modes, which are naturally associated with a slight
modification of the standard plane-wave modes. We show that this formalism
leads to the standard Rindler temperature result, and that these modes can be
canonically defined on any Cauchy surface.Comment: 15 pages, RevTe
Identifying correlations between LIGO's astronomical range and auxiliary sensors using lasso regression
The range to which the Laser Interferometer Gravitational-Wave Observatory
(LIGO) can observe astrophysical systems varies over time, limited by noise in
the instruments and their environments. Identifying and removing the sources of
noise that limit LIGO's range enables higher signal-to-noise observations and
increases the number of observations. The LIGO observatories are continuously
monitored by hundreds of thousands of auxiliary channels that may contain
information about these noise sources. This paper describes an algorithm that
uses linear regression, namely lasso (least absolute shrinkage and selection
operator) regression, to analyze all of these channels and identify a small
subset of them that can be used to reconstruct variations in LIGO's
astrophysical range. Exemplary results of the application of this method to
three different periods of LIGO Livingston data are presented, along with
computational performance and current limitations
Learning in large learning spaces:the academic engagement of a diverse group of students
Teaching larger groups of students is a growing phenomenon in HE and this brings with it, its own challenges not least for the students themselves but also their lecturers. Demographic factors as well as the experiences that characterise us as individuals will impact upon our ability to learn. The pilot study reported here considered the “academic engagement” of a diverse group of students where their course is delivered in large learning environments. As a pilot study, the paper concludes with the identification of two areas which are worthy of further research. Firstly, the study highlighted that mature students were more likely to engage in learning strategies that are associated with surface learning – the binary opposite to which practitioners often strive to achieve. Secondly, the research suggests that students who appear to know their tutors well indicate a preference for study approaches that are likely to develop deeper learning
Direct in-gel fluorescence detection and cellular imaging of O-GlcNAc-modified proteins
We report an advanced chemoenzymatic strategy for the direct fluorescence detection, proteomic analysis, and cellular imaging of O-GlcNAc-modified proteins. O-GlcNAc residues are selectively labeled with fluorescent or biotin tags using an engineered galactosyltransferase enzyme and [3 + 2] azide−alkyne cycloaddition chemistry. We demonstrate that this approach can be used for direct in-gel detection and mass spectrometric identification of O-GlcNAc proteins, identifying 146 novel glycoproteins from the mammalian brain. Furthermore, we show that the method can be exploited to quantify dynamic changes in cellular O-GlcNAc levels and to image O-GlcNAc-glycosylated proteins within cells. As such, this strategy enables studies of O-GlcNAc glycosylation that were previously inaccessible and provides a new tool for uncovering the physiological functions of O-GlcNAc
Preserving the impossible: conservation of soft-sediment hominin footprint sites and strategies for three-dimensional digital data capture.
Human footprints provide some of the most publically emotive and tangible evidence of our ancestors. To the scientific community they provide evidence of stature, presence, behaviour and in the case of early hominins potential evidence with respect to the evolution of gait. While rare in the geological record the number of footprint sites has increased in recent years along with the analytical tools available for their study. Many of these sites are at risk from rapid erosion, including the Ileret footprints in northern Kenya which are second only in age to those at Laetoli (Tanzania). Unlithified, soft-sediment footprint sites such these pose a significant geoconservation challenge. In the first part of this paper conservation and preservation options are explored leading to the conclusion that to 'record and digitally rescue' provides the only viable approach. Key to such strategies is the increasing availability of three-dimensional data capture either via optical laser scanning and/or digital photogrammetry. Within the discipline there is a developing schism between those that favour one approach over the other and a requirement from geoconservationists and the scientific community for some form of objective appraisal of these alternatives is necessary. Consequently in the second part of this paper we evaluate these alternative approaches and the role they can play in a 'record and digitally rescue' conservation strategy. Using modern footprint data, digital models created via optical laser scanning are compared to those generated by state-of-the-art photogrammetry. Both methods give comparable although subtly different results. This data is evaluated alongside a review of field deployment issues to provide guidance to the community with respect to the factors which need to be considered in digital conservation of human/hominin footprints
Language and Groundwater: Symbolic Gradients of the Anthropocene
This article argues that geographers must study the power of words as integral parts of human–environment relationships, with particular attention to local meanings, to intervene more effectively in the Anthropocene. Words are important tools by which people come to understand environmental changes and develop plans to facilitate mitigation and adaptation or, alternatively, to postpone these responses. This project considers the portion of Texas underlain by the Ogallala aquifer as a system of communication, exploring stakeholder articulations through in-depth interviews. The semiotic concepts of gradients, grading, degradation, and grace are employed to facilitate consideration of how verbal articulations intersect with resource use, conservation, anthropogenic environmental change, and action within a highly conservative political context.Office of the VP for Researc
Cellular and humoral immune responses and protection against schistosomes induced by a radiation-attenuated vaccine in chimpanzees
The radiation-attenuated Schistosoma mansoni vaccine is highly effective in rodents and primates but has never been tested in humans, primarily for safety reasons. To strengthen its status as a paradigm for a human recombinant antigen vaccine, we have undertaken a small-scale vaccination and challenge experiment in chimpanzees (Pan troglodytes). Immunological, clinical, and parasitological parameters were measured in three animals after multiple vaccinations, together with three controls, during the acute and chronic stages of challenge infection up to chemotherapeutic cure. Vaccination induced a strong in vitro proliferative response and early gamma interferon production, but type 2 cytokines were dominant by the time of challenge. The controls showed little response to challenge infection before the acute stage of the disease, initiated by egg deposition. In contrast, the responses of vaccinated animals were muted throughout the challenge period. Vaccination also induced parasite-specific immunoglobulin M (IgM) and IgG, which reached high levels at the time of challenge, while in control animals levels did not rise markedly before egg deposition. The protective effects of vaccination were manifested as an amelioration of acute disease and overall morbidity, revealed by differences in gamma-glutamyl transferase level, leukocytosis, eosinophilia, and hematocrit. Moreover, vaccinated chimpanzees had a 46% lower level of circulating cathodic antigen and a 38% reduction in fecal egg output, compared to controls, during the chronic phase of infection
Atomic-scale modeling of the deformation of nanocrystalline metals
Nanocrystalline metals, i.e. metals with grain sizes from 5 to 50 nm, display
technologically interesting properties, such as dramatically increased
hardness, increasing with decreasing grain size. Due to the small grain size,
direct atomic-scale simulations of plastic deformation of these materials are
possible, as such a polycrystalline system can be modeled with the
computational resources available today.
We present molecular dynamics simulations of nanocrystalline copper with
grain sizes up to 13 nm. Two different deformation mechanisms are active, one
is deformation through the motion of dislocations, the other is sliding in the
grain boundaries. At the grain sizes studied here the latter dominates, leading
to a softening as the grain size is reduced. This implies that there is an
``optimal'' grain size, where the hardness is maximal.
Since the grain boundaries participate actively in the deformation, it is
interesting to study the effects of introducing impurity atoms in the grain
boundaries. We study how silver atoms in the grain boundaries influence the
mechanical properties of nanocrystalline copper.Comment: 10 pages, LaTeX2e, PS figures and sty files included. To appear in
Mater. Res. Soc. Symp. Proc. vol 538 (invited paper). For related papers, see
http://www.fysik.dtu.dk/~schiotz/publist.htm
- …