2,359 research outputs found
Comparing COP Optimization with Maximizing the Coefficient of System Performance for Refrigeration Systems in Supermarkets
In recent years the energy usage of supermarkets, in particular that of their refrigeration systems, has been investigated using a variety of approaches, such as floating pressure set points and integrating the heating and refrigeration systems. Something which has not yet attracted much attention is the energy consumption of the dry condenser fans in refrigeration systems. This is surprising as it has been shown for comparable installations that including the energy consumption of these fans when optimizing the system efficiency was beneficial. To address this deficit, _COP_ maximization has been compared to optimizing the Coefficient of System Performance (_COSP_). The simple refrigeration system used for this investigation was based on a commercially available R404A/CO2 system comprising the basic components, with the condenser having extractor fans. The results show that, when the outdoor temperature is below about 15°C, there is no observable difference between these two approaches. However, when the ambient temperature increases beyond this threshold, the control method which optimizes _COSP_ is significantly better for part load conditions. This indicates that maximizing the _COP_ can lead to a sub-optimal system in terms of energy consumption under part load conditions. When the refrigeration system is at its full load point, however, both approaches produce similar results again
Building solids inside nano-space: from confined amorphous through confined solvate to confined âmetastableâ polymorph
The nanocrystallisation of complex molecules inside mesoporous hosts and control over the resulting structure is a significant challenge. To date the largest organic molecule crystallised inside the nano-pores is a known pharmaceutical intermediate â ROY (259.3 g mol1). In this work we demonstrate smart manipulation of the phase of a larger confined pharmaceutical â indomethacin (IMC, 357.8 g mol1), a substance with known conformational flexibility and complex polymorphic behaviour. We show the detailed structural analysis and the control of solid state transformations of encapsulated molecules inside the pores of mesoscopic cellular foam (MCF, pore size ca. 29 nm) and controlled pore glass (CPG, pore size ca. 55 nm). Starting from confined amorphous IMC we drive crystallisation into a confined methanol solvate, which upon vacuum drying leads to the stabilised rare form V of IMC inside the MCF host. In contrast to the pure form, encapsulated form V does not transform into a more stable polymorph upon heating. The size of the constraining pores and the drug concentration within the pores determine whether the amorphous state of the drug is stabilised or it recrystallises into confined nanocrystals. The work presents, in a critical manner, an application of complementary techniques (DSC, PXRD, solid-state NMR, N2 adsorption) to confirm unambiguously the phase transitions under confinement and offers a comprehensive strategy towards the formation and control of nano-crystalline encapsulated organic solids
Five-Brane Superpotentials and Heterotic/F-theory Duality
Under heterotic/F-theory duality it was argued that a wide class of heterotic
five-branes is mapped into the geometry of an F-theory compactification
manifold. In four-dimensional compactifications this identifies a five-brane
wrapped on a curve in the base of an elliptically fibered Calabi-Yau threefold
with a specific F-theory Calabi-Yau fourfold containing the blow-up of the
five-brane curve. We argue that this duality can be reformulated by first
constructing a non-Calabi-Yau heterotic threefold by blowing up the curve of
the five-brane into a divisor with five-brane flux. Employing
heterotic/F-theory duality this leads us to the construction of a Calabi-Yau
fourfold and four-form flux. Moreover, we obtain an explicit map between the
five-brane superpotential and an F-theory flux superpotential. The map of the
open-closed deformation problem of a five-brane in a compact Calabi-Yau
threefold into a deformation problem of complex structures on a dual Calabi-Yau
fourfold with four-form flux provides a powerful tool to explicitly compute the
five-brane superpotential.Comment: 43 pages, v2: minor correction
A Sporadic Case of Mal de Meleda Caused by Gene Mutation in SLURP-1 in Korea
Mal de Meleda (MDM), also known as keratoderma palmoplantaris transgrediens, is a rare inherited form of palmoplantar keratoderma. It is characterized by erythema and hyperkeratosis of the palms and soles, extending to the dorsal aspects of the hands and feet. A 15-year-old Korean female presented with sharply demarcated hyperkeratotic plaques on the palms and soles, which extended to the dorsal surfaces of the hands and feet, in a "glove-and-socks" distribution. The histopathologic study showed marked hyperkeratosis, acanthosis, and normogranulosis, without epidermolysis. Her genetic study detected compound heterozygous mutation in exon 3 of the ARS gene encoding SLURP-1. Family history did not reveal any other affected members and no consanguineous relationship was found. In view of these findings, we diagnosed this case as the first reported sporadic case of MDM in Korea, the farthest location from the endemic island of Meleda
Strong Water Absorption in the Dayside Emission Spectrum of the Planet HD 189733b
Recent observations of the extrasolar planet HD 189733b did not reveal the
presence of water in the emission spectrum of the planet. Yet models of such
'Hot Jupiter' planets predict an abundance of atmospheric water vapour.
Validating and constraining these models is crucial for understanding the
physics and chemistry of planetary atmospheres in extreme environments.
Indications of the presence of water in the atmosphere of HD 189733b have
recently been found in transmission spectra, where the planet's atmosphere
selectively absorbs the light of the parent star, and in broadband photometry.
Here we report on the detection of strong water absorption in a high
signal-to-noise, mid-infrared emission spectrum of the planet itself. We find
both a strong downturn in the flux ratio below 10 microns and discrete spectral
features that are characteristic of strong absorption by water vapour. The
differences between these and previous observations are significant and admit
the possibility that predicted planetary-scale dynamical weather structures
might alter the emission spectrum over time. Models that match the observed
spectrum and the broadband photometry suggest that heat distribution from the
dayside to the night side is weak. Reconciling this with the high night side
temperature will require a better understanding of atmospheric circulation or
possible additional energy sources.Comment: 11 pages, 1 figure, published in Natur
Magnetism in reduced dimensions
We propose a short overview of a few selected issues of magnetism in reduced
dimensions, which are the most relevant to set the background for more
specialized contributions to the present Special Issue. Magnetic anisotropy in
reduced dimensions is discussed, on a theoretical basis, then with experimental
reports and views from surface to single-atom anisotropy. Then conventional
magnetization states are reviewed, including macrospins, single domains,
multidomains, and domain walls in stripes. Dipolar coupling is examined for
lateral interactions in arrays, and for interlayer interactions in films and
dots. Finally thermally-assisted magnetization reversal and superparamagnetism
are presented. For each topic we sought a balance between well established
knowledge and recent developments.Comment: 13 pages. Part of a Special Issue of the C. R. Physique devoted to
spinelectronics (2005
Achieving Consensus in the Development of an Online Intervention Designed to Effectively Support Midwives in Work-Related Psychological Distress: Protocol for a Delphi Study
BACKGROUND: The development of an online intervention designed to effectively support midwives in work-related psychological distress will be challenging due to the ethical, practical, and therapeutic issues surrounding its design. Related literature suggests that midwives may require an anonymous, confidential, and therapeutic platform that facilitates amnesty and nonpunitive approaches to remedy ill health. However, it is unclear which requirements may be most salient to midwifery populations. OBJECTIVE: The objective of this paper is to describe the design of a Delphi study, intended to achieve expert consensus on the needs of midwives in work-related psychological distress who may be supported via an online intervention. This protocol may also serve as a research framework for similar studies to be modeled upon. METHODS: A heterogeneous sample of at least thirty experts on psychological well-being and distress associated with midwifery work will be recruited. Their opinions regarding the development of an online intervention designed to support midwives in work-related psychological distress will be collected through 2 rounds of questioning, via the Delphi Technique. When 60% (â„18, assuming the minimum is 30) of panelists score within 2 adjacent points on a 7-point scale, consensus will be acknowledged. This Delphi study protocol will invite both qualitative and quantitative outcomes. RESULTS: This study is currently in development. It is financially supported by a full-time scholarship at the Centre for Technology Enabled Health Research at Coventry University (Coventry, UK). The implementation of this Delphi study is anticipated to occur during the autumn of 2015. CONCLUSIONS: The results of this study will direct the development of an online intervention designed to support midwives in work-related psychological distress, summarize expert driven consensus, and direct future research
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