124,590 research outputs found
Simulation of quark-gluon plasma initial states with Monte-Carlo EKRT model
No full textTutkin tässä väitöskirjassa ultrarelativistisissa raskasionitörmäyksissä syntyvän
kvarkki-gluoniplasman (QGP) hydrodynaamista alkutilaa. Olen ohjelmoinut tätä
tarkoitusta varten alusta alkaen uuden Monte Carlo (MC) -toteutuksen jo menestyneestä
Eskola-Kajantie-Ruuskanen-Tuominen (EKRT) alkutilamallista. MCEKRT
-mallissa raskasionitörmäyksessä syntyvää energiatiheyttä mallinnetaan
minijettien avulla. Minijetit ovat kvanttiväridynamiikan häiriöteorialla (pQCD)
tuotettuja kvarkkeja ja gluoneja, joilla on erittäin pieni poikittaisliikemäärä pT—
jopa 1 GeV. Mallin keskeinen rakennusosa on saturaatio-oletus, joka ottaa huomioon
paikalliset ainetiheyden vaihtelut törmäyksestä toiseen (EbyE). Saturaation
tehtävä on dynaamisesti rajoittaa tuotettujen minijettien multiplisiteettiä.
Sen ohella, että uudessa MC-EKRT:ssä minijettien tuotto vaihtelee EbyE, mallin
tärkein uusi ominaisuus on tuotetun QGP-alkutilan rapiditeettiriippuvuus. Koska
minijettien neliliikemäärät tunnetaan, voidaan myös QGP-alkutilan energialiikemäärätensori
T<sup>μν</sup> laskea jokaiselle törmäykselle erikseen. Tämä mahdollistaa
plasman rapiditeettiriippuvaisten suureiden 3+1 ulotteisen (3+1D) hydrodynaamisen
simulaation. Toinen merkittävä uusi ominaisuus on partonien jakaumafunktiot
(PDF:t), jotka ottavat huomioon paikkariippuvuuden ydinvarjostuksessa
uudella tavalla, joka sallii myös kaikkein voimakkaimmat tiheysvaihtelut ydinaineessa.
Tekemääni tapahtumageneraattoriin on sisällytetty myös energian ja
valenssikvarkkien lukumäärien säilymisvaatimus, sekä nukleonien alirakennemalli,
ja lisäksi sen tuottamien minijettien partonimakua seurataan.
MC-EKRT-tapahtumageneraattorin ytimessä on kahden jetin tuottamisen
inklusiivisen pQCD-vaikutusalan σjet laskeminen ydinvarjostuksella kahden nukleonin
törmäyksessä. Käytimme samaa laskentaa artikkelissa [PI] tutkiessamme
tarvetta ottaa huomioon ydinvarjostus Monte Carlo Glauber -malleissa käyttämällä
rajoitteina viimeaikaisia kokeellisia LHC-tuloksia raskaiden vektoribosonien
tuotosta. Artikkelissa [PII] käymme MC-EKRT -mallin yksityiskohtaisesti läpi
ja annamme esimerkin MC-EKRT-alkutilojen käytöstä keskeisyysluokkakeskiarvoistetussa
3+1D hydrodynaamisessa simulaatiossa. Artikkeli [PIII] havainnollistaa
MC-EKRT-alkutilojen käyttöä puskuinvariantissa 2+1D EbyE hydrodynaamisessa
simulaatiossa. Tuottamamme teoreettiset ennusteet yhtenevät erinomaisesti
kokeellisten tulosten kanssa varattujen hiukkasten multiplisiteetin rapiditeettiriippuvuudesta
dN<sub>ch</sub>/dη lyijy–lyijy –törmäyksissä energioilla √sNN = 5.02 TeV ja 2.76 TeV, sekä kulta–kulta –törmäyksissä energialla
√sNN = 200 GeV. Samoin vastaavien virtauskertoimien v<sub>n</sub> lasketut arvot olivat hyvin yhteneviä kokeellisesti
havaittujen kanssa.In this thesis, the initial state of the quark gluon plasma (QGP) generated in ultrarelativistic
heavy-ion collisions is studied. For this purpose, the author has created
from scratch a completely new Monte-Carlo (MC) implementation of the
successful Eskola-Kajantie-Ruuskanen-Tuominen (EKRT) initial state model. In
this model, the energy density generated in the heavy-ion collision is modelled
via minijets, small-down to 1 GeV-transverse momentum pT quarks and gluons,
produced via perturbative Quantum Chromodynamics (pQCD). A key ingredient
is the saturation conjecture, here a local version which fluctuates eventby-
event (EbyE), which dynamically controls the generated minijet multiplicity.
Among the EbyE fluctuating minijet production, the most important new feature
of the model is the rapidity dependence of the output. As the four-momentum
of the minijets is fully known, the EbyE fluctuating energy–momentum tensor
T<sup>μν</sup> of the QGP initial state can be computed, enabling 3+1D fluid dynamical
simulations producing rapidity dependent observables. Another novel feature
are the developed parton distribution functions (PDFs) which include spatial dependence
in nuclear shadowing in a new way that allows also for the largest
density fluctuations in the nuclear matter. Also energy conservation and valence
quark number conservation are now considered. Among its other features, the
new MC-EKRT event generator includes also a nucleon substructure model and
the tracking of the partonic flavour of the generated minijets.
The heart of the MC-EKRT event generator, the calculation of the inclusive
pQCD cross section of producing two jets in a nucleon–nucleon collision σjet with
nuclear shadowing, is employed in the article [PI] to investigate the possibility
of the need to account for nuclear shadowing in Monte-Carlo Glauber models
by using recent experimental data on heavy vector boson production at the LHC
as constraints. The article [PII] introduces the MC-EKRT model in detail. The articles
[PII] and [PIII] demonstrate the usage of the MC-EKRT initial states in a
centrality-class averaged 3+1D hydrodynamical simulation ([PII]) and in boost
independent 2+1D EbyE fluid simulation ([PIII]), yielding excellent agreement
with the experimental data in the observed rapidity distributions of the charged
particle multiplicity dNch/dη in Pb+Pb collisions at √sNN = 5.02 and 2.76 TeV,
and in Au+Au collisions at √sNN = 200 GeV, and in their corresponding observed
flow coefficients v<sub>n</sub>.unknown accessibilityei tietoa saavutettavuudest
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
First report on the cirratulid (Annelida, Polychaeta) reefs from the Miocene Chilcatay and Pisco Formations (East Pisco Basin, Peru)
No full textTube-dwelling cirratulids from the Miocene Chilcatay and Pisco Formations of southern Peru are described herein for the first time. These worms constitute tube aggregates cropping out in Burdigalian and Tortonian strata of the East Pisco Basin. These specimens are here referred to the extinct species Diplochaetetes mexicanus Wilson, 1986, which was so far known from the Oligocene and lower Miocene of the Pacific Mexico. The new finds represent the first described fossil record of cirratulids from South America. Different morphologies of the tube aggregates are described, as well as their internal framework and the tube wall features. The palaeoecological and palaeobiogeographical implications of these Miocene cirratulid reefs are then discussed
Pragmatic Case Studies as a Source of Unity in Applied Psychology
No full textTo unify or not to unify applied psychology: that is the question. In this article we review pendulum swings in the historical efforts to answer this question—from a comprehensive, positivist, “top-down,” deductive yes between the 1930s and the early 60s, to a postmodern no since then. A rationale and proposal for a limited, “bottom-up,” inductive yes in applied psychology is then presented, employing a case-based paradigm that integrates both positivist and postmodern themes and components. This paradigm is labeled “pragmatic psychology” and, its specific use of case studies, the “Pragmatic Case Study Method” (“PCS Method”). We call for the creation of peer-reviewed journal-databases of pragmatic case studies as a foundational source of unifying applied knowledge in our discipline. As one example, the potential of the PCS Method for unifying different angles of theoretical regard is illustrated in an area of applied psychology, psychotherapy, via the case of Mrs. B. The article then turns to the broader historical and epistemological arguments for the unifying nature of the PCS Method in both applied and basic psychology.Peer reviewe
An investigation of vermetid reefs from the Miocene of Peru, with the description of a new species
No full textExquisitely preserved fossils of a new reef-building vermetid species from shallow-marine lower Miocene (Burdigalian) deposits of the Chilcatay Formation and upper Miocene (Tortonian) sediments of the Pisco Formation of Peru are here reported and described in detail for the first time. These finds are assigned to the living genus Thylacodes and recognized as representatives of a new species, Thylacodes devriesi sp. nov. This new taxon is known by long, almost straight tube-like shells that display peculiar ornamentations in form of striated lamellae and are arranged in an organ-pipe fashion. This discovery represents an important addition to the knowledge of the systematics and distribution of Thylacodes in South America in the geological past. Paleoenvironmental and taphonomic inferences drawn by the fossil remains of this reef-forming species are herein discussed for both the Chilcatay and Pisco Formations in the broader framework of the South American fossil record of Vermetidae
Dr. Edwin Wright Collection: Author Unknown
No full textNotes - The author relates several short stories about his neighbours including Alex McDonell, homesteading and life around Meanook and Athabasca (1 page
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
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