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A Survey of the Corrosion of Martensitic and Ferritic Stainless Steels in Pressurized Water
>The corrosion resistance of mantensitic and ferritic austenitic stainless steels and carbon steels in pressurized water at 500 to 600 deg F is compared. Included are specific out-of-pile data for austenitic stainless steels, AISI types types 410, 420, 431, and 440C; the ferritic AISI types 430, 442, and 446; the precipitation-hardening type 17-4PH; and carbon steels, ASTM 212 A and B. Available corrosion results obtained under irradiation at exposures in the range of 7 x 10/sup 16/ to 3 x 10/sup 19/ nvt are also included for types 304, types of martensitic and ferritic stainless steels which were evaluated do not contain nickel. For application where it is desirable to minimize Co/sup 58/ activity produced from nickel, selection of a martensitic or ferritic stainless steel may be more appropriate than choosing the more popular nickel-bearing austenitic stainless steel or a fuel-element cladding material. Interpretation of the data indicates that, on the average, martensitic and ferritic stainless steels corrode more rapidly than austenitic alloys but more slowly than carbon and low-alloy steels. Under selected controlled water conditions or under irradiation, the corrosion of the nickel-free stainless steels appears to differ little from the austenitics. The corrosion of martensitic and ferritic stainless steels in pressurized-water systems therefore does not appear of such magnitude as to rule out development of these materials as the cladding fuel elements for specific applications. (auth
Quantification of hydroxyacetone and glycolaldehyde using chemical ionization mass spectrometry
Chemical ionization mass spectrometry (CIMS) enables online, rapid, in situ detection and quantification of hydroxyacetone and glycolaldehyde. Two different CIMS approaches are demonstrated employing the strengths of single quadrupole mass spectrometry and triple quadrupole (tandem) mass spectrometry. Both methods are generally capable of the measurement of hydroxyacetone, an analyte with known but minimal isobaric interferences. Tandem mass spectrometry provides direct separation of the isobaric compounds glycolaldehyde and acetic acid using distinct, collision-induced dissociation daughter ions. The single quadrupole CIMS measurement of glycolaldehyde was demonstrated during the ARCTAS-CARB (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites - California Air Resources Board) 2008 campaign, while triple quadrupole CIMS measurements of glycolaldehyde and hydroxyacetone were demonstrated during the BEARPEX (Biosphere Effects on Aerosols and Photochemistry Experiment) 2009 campaign. Enhancement ratios of glycolaldehyde in ambient biomass-burning plumes are reported for the ARCTAS-CARB campaign. BEARPEX observations are compared to simple photochemical box model predictions of biogenic volatile organic compound oxidation at the site
Sonic crystal lenses that obey Lensmaker's formula
This paper presents a theoretical study of the phenomenon of acoustic imaging
by sonic crystals, which are made of two-dimensional regular arrays of rigid
cylinders placed in parallel in air. The scattering of acoustic waves is
computed using the standard multiple scattering theory, and the band structures
are computed by the plane-wave expansion method. It is shown that properly
arranged arrays not only can behave as acoustic lenses, but also the focusing
effect can be well described by Lensmaker's formula. Possible applications are
also discussed.Comment: 4 pages, 5 figure
Theoretical studies of the historical development of the accounting discipline: a review and evidence
Many existing studies of the development of accounting thought have either been atheoretical or have adopted Kuhn's model of scientific growth. The limitations of this 35-year-old model are discussed. Four different general neo-Kuhnian models of scholarly knowledge development are reviewed and compared with reference to an analytical matrix. The models are found to be mutually consistent, with each focusing on a different aspect of development. A composite model is proposed. Based on a hand-crafted database, author co-citation analysis is used to map empirically the entire literature structure of the accounting discipline during two consecutive time periods, 1972–81 and 1982–90. The changing structure of the accounting literature is interpreted using the proposed composite model of scholarly knowledge development
LBQS 0103-2753: A 0.3 Arcsec Binary Quasar
Imaging and spectroscopy with HST show that LBQS 0103-2753 (V = 17.8, z =
0.848) is a binary quasar with a separation of 0.3 arcsec or 2.3 kpc. This is
by far the smallest separation binary quasar reported to date. The two
components have very different spectra, including the presence of strong broad
absorption lines (BALs) in component A only. The emission-line redshifts, based
on the broad high ionization C IV lines, are z_A = 0.834 and z_B = 0.858; their
difference is 3900 km/s in velocity units. The broad C IV lines, however, are
probably not a good indicator of systemic redshift; and LBQS 0103-2753 A and B
could have a much smaller systemic redshift difference, like the other known
binary quasars. If the systemic redshift difference is small, then LBQS
0103-2753 would most likely be a galaxy merger that has led to a binary
supermassive black hole. There is now one known 0.3 arcsec binary among roughly
500 QSOs that have been observed in a way that would reveal such a close
binary. This suggests that QSO activity is substantially more likely for black
hole binaries at spacings ~2 kpc than at ~15 to 60 kpc. Between 1987 and 1998,
the observed Mg II BAL disappeared.Comment: 12 pages LATEX with 3 EPS figures; uses aaspp4.sty. Accepted for
publication in The Astrophysical Journal Letters, volume 550 (2001 March 20
Conservation of oceanic island floras: Present and future global challenges
Currentthreatstotheplanet’sbiodiversityareunprecedented,andtheyparticularlyimperilinsular
floras.Inthisinvestigation,weusethethreatfactorsidentifiedbytheMillenniumEcosystem
Assessmentasthemaindriversofbiodiversitylossonislandstodefineandrank13current,continuing
threatstotheplantdiversityofninefocalarchipelagoswherevolcanicorigin(orintheSeychellesa
prolongedisolationafteracontinentalorigin)hasproducedahighdegreeofendemicityandfragilityin
the faceofhabitatalteration.Wealsoconductaglobalendangermentassessmentbasedonthe
numbersofinsularendemicplantsintheendangered(EN)andcriticallyendangered(CR)IUCN
categoriesfor53islandgroupswithanestimated9951endemicplantspecies,providinga
representativesampleoftheworld’sinsularsystemsandtheirfloristicrichness.Ouranalysesindicate
that isolationdoesnotsignificantlyinfluenceendangerment,butplantendemicsfromverysmall
islandsaremoreoftencriticallyendangered.Weestimatethatbetween3500and6800oftheestimated
70,000 insularendemicplantspeciesworldwidemightbehighlythreatened(CR+EN)andbetweenca.
2000 and2800ofthemincriticaldangerofextinction(CR).Basedontheseanalyses,andona
worldwideliteraturereviewofthebiologicalthreatfactorsconsidered,weidentifychallenging
questionsforconservationresearch,asking(i)whatarethemosturgentprioritiesfortheconservation
of insularspeciesandfloras,and(ii)withtheknowledgeandassetsavailable,howcanweimprovethe
impactofconservationscienceandpracticeonthepreservationofislandbiodiversity?Ouranalysis
indicatesthatthesynergisticactionofmanythreatfactorscaninducemajorecologicaldisturbances,
leadingtomultipleextinctions.Wereviewweaknessesandstrengthsinconservationresearchand
managementintheninefocalarchipelagos,andhighlighttheurgentneedforconservationscientiststo
shareknowledgeandexpertise,identifyanddiscusscommonchallenges,andformulatemulti-
disciplinaryconservationobjectivesforinsularplantendemicsworldwide.Toourknowledge,thisisthe
mostup-to-dateandcomprehensivesurveyyettoreviewthethreatfactorstonativeplantsonoceanic
islandsanddefinepriorityresearchquestions
Geographically touring the eastern bloc: British geography, travel cultures and the Cold War
This paper considers the role of travel in the generation of geographical knowledge of the eastern bloc by British geographers. Based on oral history and surveys of published work, the paper examines the roles of three kinds of travel experience: individual private travels, tours via state tourist agencies, and tours by academic delegations. Examples are drawn from across the eastern bloc, including the USSR, Poland, Romania, East Germany and Albania. The relationship between travel and publication is addressed, notably within textbooks, and in the Geographical Magazine. The study argues for the extension of accounts of cultures of geographical travel, and seeks to supplement the existing historiography of Cold War geography
Academic team formation as evolving hypergraphs
This paper quantitatively explores the social and socio-semantic patterns of
constitution of academic collaboration teams. To this end, we broadly underline
two critical features of social networks of knowledge-based collaboration:
first, they essentially consist of group-level interactions which call for
team-centered approaches. Formally, this induces the use of hypergraphs and
n-adic interactions, rather than traditional dyadic frameworks of interaction
such as graphs, binding only pairs of agents. Second, we advocate the joint
consideration of structural and semantic features, as collaborations are
allegedly constrained by both of them. Considering these provisions, we propose
a framework which principally enables us to empirically test a series of
hypotheses related to academic team formation patterns. In particular, we
exhibit and characterize the influence of an implicit group structure driving
recurrent team formation processes. On the whole, innovative production does
not appear to be correlated with more original teams, while a polarization
appears between groups composed of experts only or non-experts only, altogether
corresponding to collectives with a high rate of repeated interactions
Insights into hydroxyl measurements and atmospheric oxidation in a California forest
The understanding of oxidation in forest atmospheres is being challenged by measurements of unexpectedly large amounts of hydroxyl (OH). A significant number of these OH measurements were made by laser-induced fluorescence in low-pressure detection chambers (called Fluorescence Assay with Gas Expansion (FAGE)) using the Penn State Ground-based Tropospheric Hydrogen Oxides Sensor (GTHOS). We deployed a new chemical removal method to measure OH in parallel with the traditional FAGE method in a California forest. The new method gives on average only 40–60% of the OH from the traditional method and this discrepancy is temperature dependent. Evidence indicates that the new method measures atmospheric OH while the traditional method is affected by internally generated OH, possibly from oxidation of biogenic volatile organic compounds. The improved agreement between OH measured by this new technique and modeled OH suggests that oxidation chemistry in at least one forest atmosphere is better understood than previously thought
Approximating the limit: the interaction between 'almost' and some temporal connectives in Italian
International audienceThis paper focuses on the interpretation of the Italian approximative adverb 'almost' by primarily looking at cases in which it modifies temporal connectives, a domain which, to our knowledge, has been largely unexplored thus far. Consideration of this domain supports the need for a scalar account of the semantics of (close in spirit to Hitzeman's semantic analysis of , in: Canakis et al. (eds) Papers from the 28th regional meeting of the Chicago Linguistic Society, 1992). When paired with suitable analyses of temporal connectives, such an account can provide a simple explanation of the patterns of implication that are observed when modifies locational (e.g. 'when'), directional (e.g. 'until' and 'since'), and event-sequencing temporal connectives (e.g. 'before' and 'after'). A challenging empirical phenomenon that is observed is a contrast between the modification of and by , on the one hand, and the modification of and by the same adverb, on the other. While and behave symmetrically, a puzzling asymmetry is observed between and . To explain the asymmetry, we propose an analysis of and on which the former has the meaning of the temporal comparative 'earlier', while the latter is seen as an atomic predicate denoting temporal succession between events (Del Prete, Nat Lang Semantics 16:157-203, 2008). We show that the same pattern of implication observed for is attested when modifies overt comparatives, and propose a pragmatic analysis of this pattern that uniformly applies to both cases, thus providing new evidence for the claim that is underlyingly a comparative. A major point of this paper is a discussion of the notion of scale which is relevant for the semantics of ; in particular, we show that the notion of Horn (entailment-based) scale is not well-suited for handling modification of temporal connectives, and that a more general notion of scale is required in order to provide a uniform analysis of as a cross-categorial modifier
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