3,146 research outputs found
20 cm VLA Radio-Continuum Study of M31 - Images and Point Source Catalogues DR2: Extraction of a supernova remnant sample
We present Data Release 2 of the Point Source Catalogue created from a series
of previously constructed radio-continuum images of M31 at lambda=20 cm (nu=1.4
GHz) from archived VLA observations. In total, we identify a collection of 916
unique discrete radio sources across the field of M31. Comparing these detected
sources to those listed by Gelfand et al. (2004) at lambda=92 cm, the spectral
index of 98 sources has been derived. The majority (73%) of these sources
exhibit a spectral index of alpha <-0.6, indicating that their emission is
predominantly non-thermal in nature, which is typical for background objects
and Supernova Remnants (SNRs). Additionally, we investigate the presence of
radio counterparts for some 156 SNRs and SNR candidates, finding a total of
only 13 of these object in our images within a 5 arcsec search area. Auxiliary
optical, radio and X-ray catalogs were cross referenced highlighting a small
population of SNR and SNR candidates common to multi-frequency domains
Nuclear and ionic charge distribution experiment on ISEE-1 and ISEE-3
The experimental work carried out under this contract is a continuation of that originally performed under Contracts NAS5-20062 and NAS5-26739. The data analyzed are from the Max-Planck Institut/Univ. of Maryland experiment on ISEE-1 and ISEE-3. Each spacecraft experiment consists of a nearly identical set of three sensors (designated the ULECA, ULEWAT, and ULEZEQ sensors) designed to measure the energy spectra and composition of suprathermal and energetic ions over a broad energy range (less than 3 keV/e to more than 20 MeV/nucleon). Since the launch of ISEE's 2 and 3, the MPI/Univ. of Maryland experiments have generally performed as expected except for a partial failure of the ULEWAT sensor on ISEE-1 in August 1978. A number of scientific studies have either been completed, initiated or are at various stages of completion. A brief summary of Primary Results is given, followed by a more detailed summary of the major accomplishments at the Univ. of Maryland
Iron charge states observed in the solar wind
Solar wind measurements from the ULECA sensor of the Max-Planck-Institut/University of Maryland experiment on ISEE-3 are reported. The low energy section of approx the ULECA sensor selects particles by their energy per charge (over the range 3.6 keV/Q to 30 keV/Q) and simultaneously measures their total energy with two low-noise solid state detectors. Solar wind Fe charge state measurements from three time periods of high speed solar wind occurring during a post-shock flow and a coronal hole-associated high speed stream are presented. Analysis of the post-shock flow solar wind indicates the charge state distributions for Fe were peaked at approx +16, indicative of an unusually high coronal temperature (3,000,000 K). In contrast, the Fe charge state distribution observed in a coronal hole-associated high speed stream peaks at approx -9, indicating a much lower coronal temperature (1,400,000 K). This constitutes the first reported measurements of iron charge states in a coronal hole-associated high speed stream
Factoring complete graphs and hypergraphs into factors with few maximal cliques
For integers and let be the minimum, over all
factorizations of the complete -uniform hypergraph of order into
factors , of where is the number
of maximal cliques in . It is known that ; in fact, if
is a graph of order , then with equality iff
where is the clique number and the
independence number. In this paper we investigate when or
. We also characterize graphs of order with .Comment: 22 page
On the independence ratio of distance graphs
A distance graph is an undirected graph on the integers where two integers
are adjacent if their difference is in a prescribed distance set. The
independence ratio of a distance graph is the maximum density of an
independent set in . Lih, Liu, and Zhu [Star extremal circulant graphs, SIAM
J. Discrete Math. 12 (1999) 491--499] showed that the independence ratio is
equal to the inverse of the fractional chromatic number, thus relating the
concept to the well studied question of finding the chromatic number of
distance graphs.
We prove that the independence ratio of a distance graph is achieved by a
periodic set, and we present a framework for discharging arguments to
demonstrate upper bounds on the independence ratio. With these tools, we
determine the exact independence ratio for several infinite families of
distance sets of size three, determine asymptotic values for others, and
present several conjectures.Comment: 39 pages, 12 figures, 6 table
Irrational homeowners? How aesthetics and heritage values influence thermal retrofit decisions in the United Kingdom
In order to reduce CO2 emissions in line with UK policy, existing UK homes need to be retrofitted to high thermal standards. A large proportion of these homes have traditional or aesthetically pleasing features which people are reluctant to compromise for the sake of thermal efficiency. A minority of such dwellings are protected by statute, but millions are not. There is a dearth of structured discussion on the issues owners of such homes face when planning thermal retrofits. This study begins with a literature review of sustainable development, heritage and aesthetics. It then reports the results of qualitative interviews with retrofitting owners of such homes in Cambridge, UK. It finds homeowners struggling to balance thermal issues against a range of heritage and aesthetic concerns which often overlap or clash. Homeowners develop their own logic in working these through, and their aesthetic convictions strongly influence what happens with retrofitting. The interviews suggest that concern for the heritage embodied in the housing stock can be one reason current policy does not always engage homeowners in retrofitting.This is the accepted manuscript. The final version is available at http://www.sciencedirect.com/science/article/pii/S2214629615300566
Quantification of (p)rebound effects in retrofit policies - Why does it matter?
The ‘prebound effect’ characterises how average heating energy consumption in older homes is consistently lower than these buildings' calculated energy ratings, and helps explain why energy savings from thermal upgrades are often lower than anticipated. This paper explores the conceptual links between prebound and rebound effects and aims to quantify these behavioural effects. It applies the resulting mathematical model to empirical examples of actual and calculated energy consumption at scales of individual dwelling and national housing stock. These show that the rebound effect, as defined in econometrics literature, can only indicate proportionate reductions in energy consumption and can mask high levels of absolute consumption. The prebound effect, however, can identify under- and over-consumption regardless of rebound effects. A combination of high prebound effect and low income suggests fuel poverty, and the rebound effect here is less relevant regarding total energy consumption. Policymakers should identify housing with high prebound effects in order to eliminate fuel poverty, and be aware of inaccuracies in calculating payback time where economic viability of retrofits is mandated. Further research is needed to understand motivations and practices in households that have high prebound effects and to identify specific priority groups for thermal retrofit policy.The authors wish to thank Benoit Allibe, Marie-Helen Laurent and Jean-Narie Cayla of Electricite de France, for making data on French houses available for use in this paper.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.energy.2015.12.03
Temporal variations of the anomalous oxygen component, 1977 - 1984
A survey is of the long term temporal variations of 6.6 to 12 MeV/nucleon anomalous oxygen at 1 AU covering the period 1977 to 1984. This time interval included the recent solar maximum, with the recovery at neutron monitor energies beginning in 1982. During this time interval, 6.6 to 12 MeV/nucleon 0 fluxes decreased by at least a factor of 50, and indeed remained below the instrumental detection threshold after 1979. By late 1984, neutron monitors had recovered to roughly 1979 levels from the 1982 solar maximum, and anomalous O still remained below the detection threshold
Executives' attitudes to business slang
On cover: Commentaries and applied research for practitioners and educators. The Lincoln series of papers are designed to inform professionals and educators of developments and issues in finance and accounting today. The papers cover both commentaries and applied research. Professionals and educators who would like to share their views and research findings are welcome to contribute to the series.The purpose of this study was to go beyond the mountain of anecdotal evidence on this subject. and survey what the attitudes of executives were business slang.
The finance directors, or their nominees, of 200 of Australia's largest 1000 companies were asked to complete a questionnaire designed to seek information about actual attitudes toward business slang expressions. It was considered that finance directors would be unlikely to have vested interest in this area, unlike Public Relations Managers who are often the professional wordsmiths for their organisations.
For this study, the term "business slang expression" refers to a word or phrase usually ephemeral, often nonstandard, rarely included in dictionaries in its specific business sense - which is nonetheless used frequently in business to communicate on the job
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