1,184 research outputs found
New and old N=8 superconformal field theories in three dimensions
We show that an infinite family of N=6 d=3 superconformal Chern-Simons-matter
theories has hidden N=8 superconformal symmetry and hidden parity on the
quantum level. This family of theories is different from the one found by
Aharony, Bergman, Jafferis and Maldacena, as well as from the theories
constructed by Bagger and Lambert, and Gustavsson. We also test several
conjectural dualities between BLG theories and ABJ theories by comparing
superconformal indices of these theories.Comment: 16 pages, late
Cartan-Weyl 3-algebras and the BLG Theory I: Classification of Cartan-Weyl 3-algebras
As Lie algebras of compact connected Lie groups, semisimple Lie algebras have
wide applications in the description of continuous symmetries of physical
systems. Mathematically, semisimple Lie algebra admits a Cartan-Weyl basis of
generators which consists of a Cartan subalgebra of mutually commuting
generators H_I and a number of step generators E^\alpha that are characterized
by a root space of non-degenerate one-forms \alpha. This simple decomposition
in terms of the root space allows for a complete classification of semisimple
Lie algebras. In this paper, we introduce the analogous concept of a
Cartan-Weyl Lie 3-algebra. We analyze their structure and obtain a complete
classification of them. Many known examples of metric Lie 3-algebras (e.g. the
Lorentzian 3-algebras) are special cases of the Cartan-Weyl 3-algebras. Due to
their elegant and simple structure, we speculate that Cartan-Weyl 3-algebras
may be useful for describing some kinds of generalized symmetries. As an
application, we consider their use in the Bagger-Lambert-Gustavsson (BLG)
theory.Comment: LaTeX. 34 pages.v2. deleted some distracting paragraphs in the
introduction to bring more out the main results of the paper. typos corrected
and references adde
International standards for fetal brain structures based on serial ultrasound measurements from the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project.
OBJECTIVE: To create prescriptive growth standards for five fetal brain structures, measured by ultrasound, from healthy, well-nourished women, at low risk of impaired fetal growth and poor perinatal outcomes, taking part in the Fetal Growth Longitudinal Study (FGLS) of the INTERGROWTH-21st Project. METHODS: This was a complementary analysis of a large, population-based, multicentre, longitudinal study. We measured, in planes reconstructed from 3-dimensional (3D) ultrasound volumes of the fetal head at different time points in pregnancy, the size of the parieto-occipital fissure (POF), Sylvian fissure (SF), anterior horn of the lateral ventricle (AV), atrium of the posterior ventricle (PV) and cisterna magna (CM). The sample analysed was randomly selected from the overall FGLS population, ensuring an equal distribution amongst the eight diverse participating sites and of 3D ultrasound volumes across pregnancy (range: 15 - 36âweeks' gestation). Fractional polynomials were used to the construct standards. Growth and development of the infants were assessed at 1 and 2âyears of age to confirm their adequacy for constructing international standards. RESULTS: From the entire FGLS cohort of 4321 women, 451 (10.4%) were randomly selected. After exclusions, 3D ultrasound volumes from 442 fetuses born without congenital malformations were used to create the charts. The fetal brain structures of interest were identified in 90% of cases. All structures showed increasing size with gestation and increasing variability for the POF, SF, PV and CM. The 3rd , 5th , 50th , 95th and 97th smoothed centile are presented. The 5th centile of POF and SF were 2.8 and 4.3 at 22âweeks and 4.2 and 9.4mm at 32âweeks respectively. The 95th centile of PV and CM were 8.5 and 7.4 at 22âweeks and 8.5 and 9.4mm at 32âweeks respectively. CONCLUSIONS: We have produced prescriptive size standards for fetal brain structures based on prospectively enrolled pregnancies at low risk of abnormal outcomes. We recommend these as international standards for the assessment of measurements obtained by ultrasound from fetal brain structures
Monopoles, three-algebras and ABJM theories with supersymmetry
We extend the hermitian three-algebra formulation of ABJM theory to include
factors. With attention payed to extra factors, we refine the
classification of ABJM theories. We argue that essentially the only
allowed gauge groups are , and
and that we have only one independent Chern-Simons level in
all these cases. Our argument is based on integrality of the
Chern-Simons levels and supersymmetry. A relation between monopole operators
and Wilson lines in Chern-Simons theory suggests certain gauge representations
of the monopole operators. From this we classify cases where we can not expect
enhanced supersymmetry. We also show that there are two equivalent
formulations of ABJM theories, based on hermitian three-algebra and
quaternionic three-algebra respectively. We suggest properties of monopoles in
theories and show how these monopoles may enhance supersymmetry from
to .Comment: 52 page
Enhanced Supersymmetry of Nonrelativistic ABJM Theory
We study the supersymmetry enhancement of nonrelativistic limits of the ABJM
theory for Chern-Simons level . The special attention is paid to the
nonrelativistic limit (known as `PAAP' case) containing both particles and
antiparticles. Using supersymmetry transformations generated by the monopole
operators, we find additional 2 kinematical, 2 dynamical, and 2 conformal
supercharges for this case. Combining with the original 8 kinematical
supercharges, the total number of supercharges becomes maximal: 14
supercharges, like in the well-known PPPP limit. We obtain the corresponding
super Schr\"odinger algebra which appears to be isomorphic to the one of the
PPPP case. We also discuss the role of monopole operators in supersymmetry
enhancement and partial breaking of supersymmetry in nonrelativistic limit of
the ABJM theory.Comment: 22 pages, references added, version to appear in JHE
Baryonic symmetries and M5 branes in the AdS_4/CFT_3 correspondence
We study U(1) symmetries dual to Betti multiplets in the AdS_4/CFT_3
correspondence for M2 branes at Calabi-Yau four-fold singularities. Analysis of
the boundary conditions for vector fields in AdS_4 allows for a choice where
wrapped M5 brane states carrying non-zero charge under such symmetries can be
considered. We begin by focusing on isolated toric singularities without
vanishing six-cycles, and study in detail the cone over Q^{111}. The boundary
conditions considered are dual to a CFT where the gauge group is U(1)^2 x
SU(N)^4. We find agreement between the spectrum of gauge-invariant
baryonic-type operators in this theory and wrapped M5 brane states. Moreover,
the physics of vacua in which these symmetries are spontaneously broken
precisely matches a dual gravity analysis involving resolutions of the
singularity, where we are able to match condensates of the baryonic operators,
Goldstone bosons and global strings. We also argue more generally that theories
where the resolutions have six-cycles are expected to receive non-perturbative
corrections from M5 brane instantons. We give a general formula relating the
instanton action to normalizable harmonic two-forms, and compute it explicitly
for the Q^{222} example. The holographic interpretation of such instantons is
currently unclear.Comment: 92 pages, 10 figure
A multimodal approach to cardiovascular risk stratification in patients with type 2 diabetes incorporating retinal, genomic and clinical features
Cardiovascular diseases are a public health concern; they remain the leading cause of morbidity and mortality in patients with type 2 diabetes. Phenotypic information available from retinal fundus images and clinical measurements, in addition to genomic data, can identify relevant biomarkers of cardiovascular health. In this study, we assessed whether such biomarkers stratified risks of major adverse cardiac events (MACE). A retrospective analysis was carried out on an extract from the Tayside GoDARTS bioresource of participants with type 2 diabetes (nâ=â3,891). A total of 519 features were incorporated, summarising morphometric properties of the retinal vasculature, various single nucleotide polymorphisms (SNPs), as well as routine clinical measurements. After imputing missing features, a predictive model was developed on a randomly sampled set (nâ=â2,918) using L1-regularised logistic regression (lasso). The model was evaluated on an independent set (nâ=â973) and its performance associated with overall hazard rate after censoring (log-rank pâ<â0.0001), suggesting that multimodal features were able to capture important knowledge for MACE risk assessment. We further showed through a bootstrap analysis that all three sources of information (retinal, genetic, routine clinical) offer robust signal. Particularly robust features included: tortuousity, width gradient, and branching point retinal groupings; SNPs known to be associated with blood pressure and cardiovascular phenotypic traits; age at imaging; clinical measurements such as blood pressure and high density lipoprotein. This novel approach could be used for fast and sensitive determination of future risks associated with MACE
On thermodynamics of N=6 superconformal Chern-Simons theory
We study thermodynamics of N=6 superconformal Chern-Simons theory by
computing quantum corrections to the free energy. We find that in weakly
coupled ABJM theory on R(2) x S(1), the leading correction is non-analytic in
the 't Hooft coupling lambda, and is approximately of order lambda^2
log(lambda)^3. The free energy is expressed in terms of the scalar thermal mass
m, which is generated by screening effects. We show that this mass vanishes to
1-loop order. We then go on to 2-loop order where we find a finite and positive
mass squared m^2. We discuss differences in the calculation between Coulomb and
Lorentz gauge. Our results indicate that the free energy is a monotonic
function in lambda which interpolates smoothly to the N^(3/2) behaviour at
strong coupling.Comment: 29 pages. v2: references added. v3: minor changes, references added,
published versio
Contemporary Asian Artistic Expressions and Tourism â An Introduction
This introductory chapter presents and critically discusses the various themes underpinning this book. Firstly, it provides an examination of the notion of âcontemporary artâ, including an overview of the existing definitions and debates in the current literature. Secondly, this chapter discusses the nexus between tourism and contemporary art by providing an overview of the past studies conducted on cultural and heritage tourism. In this section, the various themes underpinning the different parts of the literature on art tourism (e.g. identity, authenticity, commoditisation and capitalism) are considered. Thirdly, a discussion on the relationship between tourism and Asian contemporary art is presented, which also includes a part problematising and questioning terms like âAsiaâ and âAsian artâ. Finally, an overview of the different chapters that constitute the backbone of this collection is offered alongside the four themes around which the book is structured
Application of Diffusion Tensor Imaging Parameters to Detect Change in Longitudinal Studies in Cerebral Small Vessel Disease.
Cerebral small vessel disease (SVD) is the major cause of vascular cognitive impairment, resulting in significant disability and reduced quality of life. Cognitive tests have been shown to be insensitive to change in longitudinal studies and, therefore, sensitive surrogate markers are needed to monitor disease progression and assess treatment effects in clinical trials. Diffusion tensor imaging (DTI) is thought to offer great potential in this regard. Sensitivity of the various parameters that can be derived from DTI is however unknown. We aimed to evaluate the differential sensitivity of DTI markers to detect SVD progression, and to estimate sample sizes required to assess therapeutic interventions aimed at halting decline based on DTI data. We investigated 99 patients with symptomatic SVD, defined as clinical lacunar syndrome with MRI confirmation of a corresponding infarct as well as confluent white matter hyperintensities over a 3 year follow-up period. We evaluated change in DTI histogram parameters using linear mixed effect models and calculated sample size estimates. Over a three-year follow-up period we observed a decline in fractional anisotropy and increase in diffusivity in white matter tissue and most parameters changed significantly. Mean diffusivity peak height was the most sensitive marker for SVD progression as it had the smallest sample size estimate. This suggests disease progression can be monitored sensitively using DTI histogram analysis and confirms DTI's potential as surrogate marker for SVD
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