1,822 research outputs found
A new genus of ovuliferous glossopterid fructifications from South Africa
Main articleA new genus of Early Permian glossopterid fructifications, Gladiopomum, is established to
accommodate pedicellate, capitate fructifications with narrow receptacles, apical spines, and very
broad wings. Two species recognized within this genus were previously assigned to Scutum Plumstead
and Hirsutum Plumstead, viz., G. dutoitides (Plumstead) comb. nov. and G. acadarense (Anderson
& Anderson) comb. nov. An additional species, G. elongatum sp. nov. is established based on material
from a new fossil locality at Rietspruit Colliery in the northern Karoo Basin. All species of
Gladiopomum are confined to the Vryheid Formation; the genus may constitute a useful biostratigraphic
index taxon for Artinskian strata throughout the Karoo Basin.Palaeo-Anthropology Scientific Trust; French Embassy in South Africa; Co-operation and Cultural Service
Simple manipulation of a microwave dressed-state ion qubit
Many schemes for implementing quantum information processing require that the atomic states used have a non-zero magnetic moment, however such magnetically sensitive states of an atom are vulnerable to decoherence due to fluctuating magnetic fields. Dressing an atom with an external field is a powerful method of reducing such decoherence [N. Timoney et al., Nature 476, 185], even if the states being dressed are strongly coupled to the environment. We introduce an experimentally simpler method of manipulating such a dressed-state qubit, which allows the implementation of general rotations of the qubit, and demonstrate this method using a trapped ytterbium ion
EEG Source Imaging Indices of Cognitive Control Show Associations with Dopamine System Genes.
Cognitive or executive control is a critical mental ability, an important marker of mental illness, and among the most heritable of neurocognitive traits. Two candidate genes, catechol-O-methyltransferase (COMT) and DRD4, which both have a roles in the regulation of cortical dopamine, have been consistently associated with cognitive control. Here, we predicted that individuals with the COMT Met/Met allele would show improved response execution and inhibition as indexed by event-related potentials in a Go/NoGo task, while individuals with the DRD4 7-repeat allele would show impaired brain activity. We used independent component analysis (ICA) to separate brain source processes contributing to high-density EEG scalp signals recorded during the task. As expected, individuals with the DRD4 7-repeat polymorphism had reduced parietal P3 source and scalp responses to response (Go) compared to those without the 7-repeat. Contrary to our expectation, the COMT homozygous Met allele was associated with a smaller frontal P3 source and scalp response to response-inhibition (NoGo) stimuli, suggesting that while more dopamine in frontal cortical areas has advantages in some tasks, it may also compromise response inhibition function. An interaction effect emerged for P3 source responses to Go stimuli. These were reduced in those with both the 7-repeat DRD4 allele and either the COMT Val/Val or the Met/Met homozygous polymorphisms but not in those with the heterozygous Val/Met polymorphism. This epistatic interaction between DRD4 and COMT replicates findings that too little or too much dopamine impairs cognitive control. The anatomic and functional separated maximally independent cortical EEG sources proved more informative than scalp channel measures for genetic studies of brain function and thus better elucidate the complex mechanisms in psychiatric illness
The Roots, Practices and Consequences of Terrorism: A Literature Review of Research in the Arts & Humanities
This report contains a literature review of Arts and Humanities research on the roots, practices and consequences of terrorism with an annotated bibliography. The literature review was carried out for the Home Office by a team at the University of Leeds between March and October 2006
Eliminating ambiguities for quantum corrections to strings moving in
We apply a physical principle, previously used to eliminate ambiguities in
quantum corrections to the 2 dimensional kink, to the case of spinning strings
moving in , thought of as another kind of two
dimensional soliton. We find that this eliminates the ambiguities and selects
the result compatible with AdS/CFT, providing a solid foundation for one of the
previous calculations, which found agreement. The method can be applied to
other classical string "solitons".Comment: 18 pages, latex; references added, comments added at end of section
4, a few words changed; footnote added on page 1
On the Fermionic Frequencies of Circular Strings
We revisit the semiclassical computation of the fluctuation spectrum around
different circular string solutions in AdS_5xS^5 and AdS_4xCP^3, starting from
the Green-Schwarz action. It has been known that the results for these
frequencies obtained from the algebraic curve and from the worldsheet
computations sometimes do not agree. In particular, different methods give
different results for the half-integer shifts in the mode numbers of the
frequencies. We find that these discrepancies can be removed if one carefully
takes into account the transition matrices in the spin bundle over the target
space.Comment: 13 pages, 1 figur
Adapting a Computational Multi Agent Model for Humpback Whale Song Research for use as a Tool for Algorithmic Composition
Humpback whales (Megaptera Novaengliae) present one of the most complex displays of cultural transmission amongst non-humans. During breeding seasons, male humpback whales create long, hierarchical songs, which are shared amongst a population. Every male in the population conforms to the same song in a population. During the breeding season these songs slowly change and the song at the end of the breeding season is significantly different from the song heard at the start of the breeding season. The song of a population can also be replaced, if a new song from a different population is introduced.This is known as song revolution. Our research focuses on building computational multi agent models, which seek to recreate these phenomena observed in the wild.Our research relies on methods inspired by computational multi agent models for the evolution of music. This interdisciplinary approach has allowed us to adapt our model so that it may be used not only as a scientific tool, but also a creative tool for algorithmic composition. This paper discusses the model in detail, and then demonstrates how it may be adapted for use as an algorithmic composition tool.Publisher PD
QCD properties of twist operators in the N=6 Chern-Simons theory
We consider twist-1, 2 operators in planar N=6 superconformal Chern-Simons
ABJM theory. We derive higher order anomalous dimensions from integrability and
test various QCD-inspired predictions known to hold in N=4 SYM. In particular,
we show that the asymptotic anomalous dimensions display intriguing remnants of
Gribov-Lipatov reciprocity and Low-Burnett-Kroll logarithmic cancellations.
Wrapping effects are also discussed and shown to be subleading at large spin.Comment: 22 pages, expanded reference
Organicity: Lessons from an Experimentation as a Service Model for Digital Civic Innovation
In the paradigm of the Smart City, cities are embracing new digital technologies and data innovation to redefine their relationship
to citizens and enterprise. Increasingly, cities are developing visions, strategies, and related digital masterplans and action groups with which
to coordinate these efforts. The European Horizon 2020 funded OrganiCity project explored a new model for providing access to all citizens
to collaboratively develop and test their ideas for managing and improving the urban environment using data. The people centred and data
driven approach of the OrganiCity project developed an Experimentation as a Service (EaaS) model across 13 cities and with 43 experiments.
In this paper, we describe the 4 key service pillars that emerged through designing a platform to enable experimentation and the associated
engagement practices required to facilitate testing in a city. The service pillars are: systematic experimentation, co-creation, federated ethics
& privacy, and management of liability & Intellectual Property Rights. The EaaS approach provided a low-risk service blueprint for city
authorities to democratically source, test and support scaling-up innovative solutions to their city challenges. Analysis of experimenter’s
projects highlighted the importance of shared infrastructure for reducing the barrier to entry for accessing the digital tools, but more importantly
highlighted the investment required, and value of, the human resources required to facilitate the process of experimentation
Light-cone gauge Hamiltonian for AdS_4 x CP^3 superstring
It is developed the phase-space formulation for the Type IIA superstring on
the AdS_4 x CP^3 background in the kappa-symmetry light-cone gauge for which
the light-like directions are taken from the D=3 Minkowski boundary of AdS_4.
After fixing bosonic light-cone gauge the superstring Hamiltonian is expressed
as a function of the transverse physical variables and in the quadratic
approximation corresponds to the light-cone gauge-fixed IIA superstring in flat
space.Comment: 12 pages, LaTeX; v2 minor improvements of the text, misprints
corrected, reference added; v3: missing terms in Eqs.(8),(53) and (56) adde
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