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Calculating the free energy of antimicrobial peptide (HHC-36) dimerization in bulk

shaqa vafa University of Guelph

December 05, 2013 PIRSA:13120043
Symmetry Enriched Quantum Spin Ices On the Pyrochlore Lattice

Gang Chen Fudan University
December 06, 2013 PIRSA:13120055
Scientific Area

Condensed Matter
No GUTs, All Glory: Charge Quantization and the Standard Model from Nonlinear Sigma Models

John Kehayias Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)
December 06, 2013 PIRSA:13120056
Scientific Area

Particle Physics
Compactifying de Sitter

Alex Dahlen Princeton University
December 10, 2013 PIRSA:13120049
Scientific Area

Cosmology
Consistency of Massive Gravity

Lavinia Heisenberg ETH Zurich - Institut für Theoretische Physik
December 10, 2013 PIRSA:13120061
Scientific Area

Cosmology
(0,2) Trialities

Abhijit Gadde Stony Brook University
December 10, 2013 PIRSA:13120062
Scientific Area

Quantum Fields and Strings
Strominger-Yau-Zaslow revisited

David Morrison University of California - Santa Barbara (UCSB)

November 21, 2004 PIRSA:04110024
Rebuilding Mathematics on a Quantum Logical Foundation

Richard deJonghe University of Illinois at Urbana-Champaign (UIUC)
December 10, 2013 PIRSA:13120060
Scientific Area

Quantum Foundations
Partially Massless Gravity
December 11, 2013 PIRSA:13120005
Scientific Area

Cosmology
holographic path to the turbulent side of gravity
- Adam Brown Stanford University
- Stephen Green Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)
December 12, 2013 PIRSA:13120066
Scientific Area

Cosmology
Curvature in terms of entanglement

Achim Kempf University of Waterloo
December 12, 2013 PIRSA:13120064
Scientific Area

Quantum Gravity
Integrability (and Near Integrability) in Matrix-valued Field Theories

Axel Cortes Cubero City University of New York (CUNY) - Department of Physics
December 13, 2013 PIRSA:13120068
Scientific Area

Quantum Fields and Strings

Calculating the free energy of antimicrobial peptide (HHC-36) dimerization in bulk

shaqa vafa University of Guelph

December 05, 2013 PIRSA:13120043

The increasing demand for antibiotics has contributed to the investigation of possible novel antibiotics by many researchers. For this purpose experimental and theoretical studies have been carried out to draw scientists' attention to antimicrobial peptides and their interaction with the surface of bacterial membranes. Their ability to disrupt the functioning of bacterial membranes has been probed from different perspectives. The most desirable antimicrobial peptides are those which do not harm plant or animals' membranes but which disrupt bacterial membranes. It has been found that some cationic antimicrobial peptides (CAPs) satisfy these requirements. CAPs interacting with the outer membrane of gram-negative bacteria and the membrane of gram-positive bacteria have been studied recently.We conduct a Molecular Dynamics simulation study of peptide-peptide interactions in physiological solutions and investigate the mechanism of CAPs aggregation since aggregation of the peptides could precede their interaction with the membrane. Different algorithms are applied to calculate the potential mean force of the aggregation process of peptides to select the most efficient one. Also we have run CD spectroscopy and calorimetry experiments to predict the structure of the peptide and measure the peptide-peptide binding enthalpy and compared these results with our simulation data. The particular CAP studied is HHC-36 a peptide selected by high throughput screening (A. Cherkasov et al ACS Chem. Biol. 2009 4 (1) pp 6574) (M. Kazemzadeh-Narbat et al Biomed. Mater. Res. Part B 2012 5 pp1344-1352) (M. Ma et al Biomed. Mater. Res. Part A 2012 2 pp278-185) which has nine amino acid residues and charge +5.
Symmetry Enriched Quantum Spin Ices On the Pyrochlore Lattice

Gang Chen Fudan University
December 06, 2013 PIRSA:13120055
Scientific Area

Condensed Matter
Quantum spin liquid (QSL) is an exotic phase of matter and provides an interesting example of emergent non-locality. Even though many materials have been proposed as candidates for QSLs, there is no direct confirmation of QSLs in any of these systems. Quantum spin ice (QSI) is a physical realization of U(1) QSLs on the pyrochlore lattice. We consider a class of electron systems in which dipolar-octupolar Kramers doublets arise on the pyrochlore lattice. In the localized limit, the Kramers doublets are described by the effective spin 1/2 pseudospins. The most general nearest-neighbor exchange model between these pseudospins is the XYZ model. We show that this XYZ model exhibit two distinct symmetry enriched QSI phases, that we dub dipolar QSI and octupolar QSI. This XYZ model is absent from the notorious sign problem for a quantum Monte Carlo simmulation. We also discuss the potential relevance to real material systems.
No GUTs, All Glory: Charge Quantization and the Standard Model from Nonlinear Sigma Models

John Kehayias Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)
December 06, 2013 PIRSA:13120056
Scientific Area

Particle Physics
I will present recent and ongoing work in collaboration with Tsutomu Yanagida and Simeon Hellerman (arXiv:1309.0692 and 1312.xxxx) on a new way to obtain charge quantization, without a GUT or monopole solution. In the CP^1 model, SU(2)_G/U(1)_H, consistency conditions for a charged field and its transformation properties over the entire group manifold lead to a charge quantization condition. By gauging the U(1)_H and identifying it with hypercharge, we find charge quantization in the SM without a monopole or GUT, purely from the structure and dynamics of the nonlinear sigma model. This is easily extended to CP^2 and general CP^k models. Phenomenologically, the CP^1 model has a fractionally charged stable Nambu-Goldstone boson (NGB), which has intriguing applications to nuclear physics and dark matter. The CP^2 model has the Higgs as the NGB. With some additional minor assumptions, anomaly freedom then leads to the matter content of a generation in the SM.
Compactifying de Sitter

Alex Dahlen Princeton University
December 10, 2013 PIRSA:13120049
Scientific Area

Cosmology
TBA
Consistency of Massive Gravity

Lavinia Heisenberg ETH Zurich - Institut für Theoretische Physik
December 10, 2013 PIRSA:13120061
Scientific Area

Cosmology
Recently there has been a successful non-linear covariant ghost-free generalization of Fierz-Pauli massive gravity theory, the dRGT theory. I will explore the cosmology in the decoupling limit of this theory. Furthermore, I will construct a Proxy theory to dRGT from the decoupling limit and study the cosmology there as well and compare the results. Finally, I will discuss the quantum consistency of the theory.
(0,2) Trialities

Abhijit Gadde Stony Brook University
December 10, 2013 PIRSA:13120062
Scientific Area

Quantum Fields and Strings
Motivated by the connection between 4-manifolds and 2d N=(0,2) theories, we study the dynamics of a fairly large class of 2d N=(0,2) gauge theories. We see that physics of such theories is very rich, much as the physics of 4d N=1 theories. We discover a new type of duality that is very reminiscent of the 4d Seiberg duality. Surprisingly, the new 2d duality is an operation of order three. We study the low energy physics and use elliptic genus to detect dynamical supersymmetry breaking.
Strominger-Yau-Zaslow revisited

David Morrison University of California - Santa Barbara (UCSB)

November 21, 2004 PIRSA:04110024
Rebuilding Mathematics on a Quantum Logical Foundation

Richard deJonghe University of Illinois at Urbana-Champaign (UIUC)
December 10, 2013 PIRSA:13120060
Scientific Area

Quantum Foundations
It is not unnatural to expect that difficulties lying at the foundations of quantum mechanics can only be resolved by literally going back and rethinking the quantum theory from first principles (namely, the principles of logic). In this talk, I will present a first-order quantum logic which generalizes the propositional quatum logic originated by Birkhoff and von Neumann as well as the standard classical predicate logic used in the development of virtually all of modern mathematics. I will then use this quantum logic to begin to build the foundations of a new ``quantum mathematics'' --- in particular a quantum set theory and a quantum arithmetic --- which has the potential to provide a completely new mathematical framework in which to develop the theory of quantum
mechanics.
Partially Massless Gravity
December 11, 2013 PIRSA:13120005
Scientific Area

Cosmology
On de Sitter space, there exists a special value for the mass of a graviton for which the linear theory propagates 4 rather than 5 degrees of freedom. If a fully non-linear version of the theory exists and can be coupled to known matter, it would have interesting properties and could solve the cosmological constant problem. I will describe evidence for and obstructions to the existence of such a theory.
holographic path to the turbulent side of gravity
- Adam Brown Stanford University
- Stephen Green Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)
December 12, 2013 PIRSA:13120066
Scientific Area

Cosmology
We study the dynamics of a 2+1 dimensional relativistic viscous conformal fluid in Minkowski spacetime. Such fluid solutions arise as duals, under the "gravity/fluid correspondence", to 3+1 dimensional asymptotically anti-de Sitter (AAdS) black brane solutions to the Einstein equation. We examine stability properties of shear flows, which correspond to hydrodynamic quasinormal modes of the black brane. We find that, for sufficiently high Reynolds number, the solution undergoes an inverse turbulent cascade to long wavelength modes. We then map this fluid solution, via the gravity/fluid duality, into a bulk metric. This suggests a new and interesting feature of the behavior of perturbed AAdS black holes and black branes, which is not readily captured by a standard quasinormal mode analysis. Namely, for sufficiently large perturbed black objects (with long-lived quasinormal modes), nonlinear effects transfer energy from short to long wavelength modes via a turbulent cascade within the metric perturbation. As long wavelength modes have slower decay, this lengthens the overall lifetime of the perturbation. We also discuss various implications of this behavior, including expectations for higher dimensions, and the possibility of predicting turbulence in more general gravitational scenarios."
Curvature in terms of entanglement

Achim Kempf University of Waterloo
December 12, 2013 PIRSA:13120064
Scientific Area

Quantum Gravity
The entanglement of the quantum field theoretic vacuum state is affected by curvature. I ask if or under which conditions the curvature of spacetime can be expressed entirely in terms of the spatial entanglement structure of the vacuum. This would open up the prospect that general relativity could be formulated in quantum theoretic terms, which should then be helpful for studies in quantum gravity.
Integrability (and Near Integrability) in Matrix-valued Field Theories

Axel Cortes Cubero City University of New York (CUNY) - Department of Physics
December 13, 2013 PIRSA:13120068
Scientific Area

Quantum Fields and Strings
The principal chiral sigma model (PCSM) in 1+1 dimensions is asymptotically free and has as SU(N)-valued field with massive excitations. We have found all the exact form factors and two-point function of the Noether-current operators at large N using the integrable bootstrap program. At finite N, only the first non-trivial form factors are found, which give a good long distance approximation for the two-point function. We show how to use these new exact results to study non-integrable deformations. One example is the PCSM coupled to a Yang-Mills field. One can approximate the spectrum of the meson-like bound states using our form factors. We also examine an anisotropic version of (2+1)-dimensional Yang-Mills theory, which can be interpreted as an array of coupled PCSM’s.

Title	Speaker(s)	Date	Collection	Type	Info	Relevance
Calculating the free energy of antimicrobial peptide (HHC-36) dimerization in bulk	shaqa vafa	2013‑12‑05	Waterloo Soft Matter Theory	Conference	View details	1
Symmetry Enriched Quantum Spin Ices On the Pyrochlore Lattice	Gang Chen	2013‑12‑06	Condensed Matter	Scientific Series	View details	1
No GUTs, All Glory: Charge Quantization and the Standard Model from Nonlinear Sigma Models	John Kehayias	2013‑12‑06	Particle Physics	Scientific Series	View details	1
Compactifying de Sitter	Alex Dahlen	2013‑12‑10	Cosmology and Gravitation	Scientific Series	View details	1
Consistency of Massive Gravity	Lavinia Heisenberg	2013‑12‑10	Cosmology and Gravitation	Scientific Series	View details	1
(0,2) Trialities	Abhijit Gadde	2013‑12‑10	Quantum Fields and Strings	Scientific Series	View details	1
Strominger-Yau-Zaslow revisited	David Morrison	2004‑11‑21	Thematic Program on The Geometry of String Theory 2004 - 2005: Mirror Symmetry	Other	View details	1
Rebuilding Mathematics on a Quantum Logical Foundation	Richard deJonghe	2013‑12‑10	Quantum Foundations	Scientific Series	View details	1
Partially Massless Gravity		2013‑12‑11	Colloquium	Scientific Series	View details	1
holographic path to the turbulent side of gravity	Adam Brown, Stephen Green	2013‑12‑12	Cosmology and Gravitation	Scientific Series	View details	1
Curvature in terms of entanglement	Achim Kempf	2013‑12‑12	Quantum Gravity	Scientific Series	View details	1
Integrability (and Near Integrability) in Matrix-valued Field Theories	Axel Cortes Cubero	2013‑12‑13	Quantum Fields and Strings	Scientific Series	View details	1

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