13,075 research outputs found
A new study of an old sink of sulfur in hot molecular cores: the sulfur residue
Sulfur appears to be depleted by an order of magnitude or more from its
elemental abundance in star-forming regions. In the last few years, numerous
observations and experiments have been performed in order to to understand the
reasons behind this depletion without providing a satisfactory explanation of
the sulfur chemistry towards high-mass star-forming cores. Several
sulfur-bearing molecules have been observed in these regions, and yet none are
abundant enough to make up the gas-phase deficit. Where, then, does this hidden
sulfur reside? This paper represents a step forward in our understanding of the
interactions among the various S-bearing species. We have incorporated recent
experimental and theoretical data into a chemical model of a hot molecular core
in order to see whether they give any indication of the identity of the sulfur
sink in these dense regions. Despite our model producing reasonable agreement
with both solid-phase and gas-phase abundances of many sulfur-bearing species,
we find that the sulfur residue detected in recent experiments takes up only ~6
per cent of the available sulfur in our simulations, rather than dominating the
sulfur budget.Comment: 13 pages, 6 colourful figures, accepted by MNRA
Lean towards learning: connecting Lean Thinking and human resource management in UK higher education
From its origins in the automotive industry, Lean Thinking is increasingly being seen as a solution to problems of efficiency and quality in other industries and sectors. In recent years attempts have been made to transfer Lean principles and practice to the higher education sector with indications of mixed consequences and debate over its suitability. This paper contributes to the debate by drawing evidence from thirty-four interviews conducted across two UK universities that have implemented Lean in some of their activities and we pay particular attention to the role of the HR function in facilitating its introduction. The findings suggest there are problems in understanding, communicating and transferring Lean Thinking in the higher education context; that, despite HR systems being vital facets of Lean, HR professionals are excluded from participation; and that as a consequence the depth and breadth of Lean application in the two institutions is very limited
DNA amplified fingerprinting, a useful tool for determination of genetic origin and diversity analysis in Citrus
We used three short repetitive nucleotide sequences [(GTG)5, (TAC)5, and (GACA)4] either as radiolabeled probes for hybridization with restricted Citrus DNA or as single primers in polymerase chain reaction amplification experiments with total genomic DNA. We tested the ability of the sequences to discriminate between seedlings of zygotic or nuclear origin in the progeny of a Volkamer lemon #Citrus volkameriana# Ten. & Pasq.) tree. The genetic variability within two species [#Citrus sinensis# (L.) Osbeck (sweet oranges) and #Citrus reticulata# Blanco and relatives (mandarins)] was evaluated. DNA amplified figerprinting with single primers was the more successful technique for discriminating between nucellular and zygotic seedlings. Although we were not able to distinguish among 10 cultivars of #C. sinensis#, all 10 #C. reticulata# cultivars tested were distinguishable. However, it still is difficult to identify the putative parents of a hybrid plant when the two parental genomes are closely related. (Résumé d'auteur
A Population of Short-Period Variable Quasars from PTF as Supermassive Black Hole Binary Candidates
Supermassive black hole binaries (SMBHBs) at sub-parsec separations should be
common in galactic nuclei, as a result of frequent galaxy mergers.
Hydrodynamical simulations of circumbinary discs predict strong periodic
modulation of the mass accretion rate on time-scales comparable to the orbital
period of the binary. As a result, SMBHBs may be recognized by the periodic
modulation of their brightness. We conducted a statistical search for periodic
variability in a sample of 35,383 spectroscopically confirmed quasars in the
photometric database of the Palomar Transient Factory (PTF). We analysed
Lomb-Scargle periodograms and assessed the significance of our findings by
modeling each individual quasar's variability as a damped random walk (DRW). We
identified 50 quasars with significant periodicity beyond the DRW model,
typically with short periods of a few hundred days. We find 33 of these to
remain significant after a re-analysis of their periodograms including
additional optical data from the intermediate-PTF and the Catalina Real-Time
Transient Survey (CRTS). Assuming that the observed periods correspond to the
redshifted orbital periods of SMBHBs, we conclude that our findings are
consistent with a population of unequal-mass SMBHBs, with a typical mass ratio
as low as q = M2/M1 ~ 0.01.Comment: MNRAS (accepted), new section 4.
Ocean response to a hurricane, part II : data tabulations and numerical modeling
Field observations of the ocean's forced stage response to three hurricanes, Norbert (1984), Josephine (1984) and Gloria (1985),
are analyzed and presented in a storm-centered coordinate system. All three hurricanes had a non-dimensional speed of O(1) and
produced a strongly rightward biased response of the ocean surface mixed layer (SML) transport and current. The maximum layer-averaged
SML currents varried from 0.8 m S-1 in response to Josephine, which was a fairly weak hurricane, to 1.7 m S.l in response to
Gloria, which was much stronger. In these two cases the current amplitude is set primarly by the strength of the wind stress and its
efficiency of coupling with the SML current, and the depth of vertical mixing of the SML. The Norbert case (SML Burger number
â 1/2) was also affected by significant pressure-coupling with the thermocline that caused appreciable upwellng by inertial pumping
and strong thermocline-depth currents, up to 0.3 m S-l, under the trailing edge of Norbert. The observed SML current has a vertical
shear in the direction of the local wind of up to 0.01 S-l. This vertical shear causes the surface current to be larger than the layer-averaged
SML current described above by typically 0.2 m S.l.Funding was provided by the Office of Naval Research
under grant No. N00014-89-J-I053
Existing healthcare facilities, refurbishment, and energy simulation
In recent years, various experts and organisations have emphasised the
need to improve existing facilities to meet targets imposed by government related to energy
consumption and carbon emissions. Demolishing existing facilities and constructing new
facilities is not always the best solution to achieve government targets and modernise
existing healthcare facilities. Also, the National Health Serviceâs (NHS) focus on new
construction in the past has contributed towards the deterioration of existing building stock
up to certain extent. Research in the area of refurbishment of existing hospitals has been
neglected despite the fact that existing facilities still account for a major proportion of NHS
healthcare building stock. To accomplish the research aim and goals, a mixed methodology
was used which include a literature review, webâbased case studies, questionnaire survey,
interviews and site visits to hospitals. A brief study of healthcare refurbishment indicates
that a specific framework for existing buildings is required because their characteristics are
different to new facilities. The function of this particular framework should be to integrate
modelling and assessment tools, and to reduce existing building energy consumption
throughout the lifeâcycle
Seasonal patterns of oral antihistamine and intranasal corticosteroid purchases from Australian community pharmacies : a retrospective observational study
Acknowledgments The abstract of this paper was presented at the Respiratory Effectiveness Group 2016 Annual Summit as a poster presentation with interim findings. The posterâs abstract was published in âPoster Abstractsâ in The Journal of Thoracic Disease (Vol. 8, Supplement 5, 5 July 2016). http://jtd.amegroups.com/article/view/8504.Peer reviewedPublisher PD
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