181 research outputs found
Principal Chiral Model without and with WZ term: Symmetries and Poisson-Lie T-Duality
Duality properties of the Principal Chiral Model are investigated
starting from a one-parameter family of its equivalent Hamiltonian descriptions
generated by a non-Abelian deformation of the cotangent space . The corresponding dual models are obtained through
duality transformations and result to be defined on the group
, which is the Poisson-Lie dual of in the Iwasawa
decomposition of the Drinfel'd double .These dual models provide an explicit realization of
Poisson-Lie T-duality. A doubled generalized parent action is then built on the
tangent space . Furthermore, a generalization of the
PCM with a WZ term is shortly discussed.Comment: 25 pages, Contribution to the Proceedings of Corfu Summer Institute
2019 "Schools and Workshops on Elementary Particle Physics and Gravity
Jacobi sigma models
We introduce a two-dimensional sigma model on surfaces with boundary and
target space a Jacobi manifold. The model yields a topological open string
theory. In the Hamiltonian approach first class constraints are derived, which
generate gauge invariance of the model under diffeomorphisms. By introducing a
metric term, a non-topological sigma model is obtained, yielding a Polyakov
action with metric and B-field, whose target space is a Jacobi manifold.Comment: 21 pages. Latex2e. Minor changes, references adde
Dissecting the heritable risk of breast cancer:From statistical methods to susceptibility genes
Decades of research have shown that rare highly penetrant mutations can promote tumorigenesis, but it is still unclear whether variants observed at high-frequency in the broader population could modulate the risk of developing cancer. Genome-wide Association Studies (GWAS) have generated a wealth of data linking single nucleotide polymorphisms (SNPs) to increased cancer risk, but the effect of these mutations are usually subtle, leaving most of cancer heritability unexplained. Understanding the role of high-frequency mutations in cancer can provide new intervention points for early diagnostics, patient stratification and treatment in malignancies with high prevalence, such as breast cancer. Here we review state-of-the-art methods to study cancer heritability using GWAS data and provide an updated map of breast cancer susceptibility loci at the SNP and gene level
The Effective Theory of Quantum Black Holes
We explore the quantum nature of black holes by introducing an effective
framework that takes into account deviations from the classical results. The
approach is based on introducing quantum corrections to the classical
Schwarzschild geometry in a way that is consistent with the physical scales of
the black hole and its classical symmetries. This is achieved by organizing the
quantum corrections in inverse powers of a physical distance. By solving the
system in a self-consistent way we show that the derived physical quantities,
such as event horizons, temperature and entropy can be expressed in a well
defined expansion in the inverse powers of the black hole mass. The approach
captures the general form of the quantum corrections to black hole physics
without requiring to commit to a specific model of quantum gravity.Comment: Revised version, added references, refined text and added explanatory
footnote. 23 pages, 13 figure
Poisson-Lie T-Duality of WZW Model via Current Algebra Deformation
Poisson-Lie T-duality of the Wess-Zumino-Witten (WZW) model having the group
manifold of as target space is investigated. The whole construction
relies on the deformation of the affine current algebra of the model, the
semi-direct sum ,
to the fully semisimple Kac-Moody algebra
. A two-parameter family of models
with as target phase space is obtained so that Poisson-Lie
T-duality is realised as an rotation in the phase space. The dual
family shares the same phase space but its configuration space is
, the Poisson-Lie dual of the group . A parent action
with doubled degrees of freedom on is defined, together with
its Hamiltonian description.Comment: 46 page
Foreword for Visualized Cancer Medicine: The era for dynamic visuals is here
We have seen in many circumstances of cancer research and clinical practice that the process itself is more critical and valuable than the result. For better presenting the natural movements of studied subject as well as the processes of medical intervention in treating patient, we proudly launch Visualized Cancer Medicine as a peer-reviewed publication platform covering all relevant topics in which videos play a critical role for presenting the results or the procedures. We appreciate the constant supports from our rigorous authors, dedicating editorial staff members, creative informative technology engineers, and enthusiastic readers. We hope that our small step of establishing Visualized Cancer Medicine for better scientific presentation would foster giant leaps of our understanding on cancer, which would subsequently benefit human being in many ways
N=1 Matter from Fractional Branes
We study a bound state of fractional D3-branes localized inside the
world-volume of fractional D7-branes on the orbifold C^3/Z_2 x Z_2. We
determine the open string spectrum that leads to N=1 U(N1)xU(N2)xU(N3)xU(N4)
gauge theory with matter having the number of D7-branes as a flavor index. We
derive the linearized boundary action of the D7-brane on this orbifold using
the boundary state formalism and we discuss the tadpole cancellation. After
computing the asymptotic expression of the supergravity solution the anomalies
of the gauge theory are reproduced.Comment: LaTeX 20 pages, 1 figure, small changes and references adde
Fragility Fractures of the Acetabulum: Current Concepts for Improving Patients’ Outcomes
The incidence of fragility fractures of the acetabulum (FFA) is constantly increasing. Generally, these fractures are related to a fall on the greater trochanter involving the anterior column. The management of FFA is extremely difficult considering both patients’ comorbidities and poor bone quality. Both non-operative and several operative treatment protocols are available, and the choice among them is still ambiguous. The proposed surgical techniques for FFA [namely open reduction and internal fixation (ORIF), percutaneous fixation and total hip arthroplasty (THA)] are associated with a high complication rate. The treatment with the higher early mortality is the ORIF + THA, while the one with the lowest is the non-operative. However, at longer follow-up, this difference dreadfully change is becoming the opposite. Frequently ORIF, percutaneous fixation, and non-operative treatment need a subsequent re-operation through a THA. This latter could be extremely difficult, because of poor bone quality, acetabular mal union/non-union, bone gaps and hardware retention. However, the outcomes of each of the proposed treatment are mostly poor and controverted; therefore, a comprehensive patient evaluation and an accurate fracture description are required to appropriately manage acetabular fracture in the elderly
- …