Hybrid Monte Carlo Simulation of Graphene on the Hexagonal Lattice

We present a method for direct hybrid Monte Carlo simulation of graphene on the hexagonal lattice. We compare the results of the simulation with exact results for a unit hexagonal cell system, where the Hamiltonian can be solved analytically.Comment: 5 pages, 4 figure

Quantum computing for lattice supersymmetry

Quantum computing promises the possibility of studying the real-time dynamics of non-perturbative quantum field theories while avoiding the sign problem that obstructs conventional lattice approaches. Current and near-future quantum devices are severely limited by noise, making investigations of simple low-dimensional lattice systems ideal testbeds for algorithm development. Considering simple supersymmetric systems, such as supersymmetric quantum mechanics with different superpotentials, allows for the analysis of phenomena like dynamical supersymmetry breaking. We present ongoing work applying quantum computing techniques to study such theories, targeting real-time dynamics and supersymmetry breaking effects

Thermal phase structure of dimensionally reduced super-Yang-Mills

We present our current results from ongoing lattice investigations of the Berenstein-Maldacena-Nastase deformation of maximally supersymmetric Yang-Mills quantum mechanics. We focus on the thermal phase structure of this theory, which depends on both the temperature T and the deformation parameter μ, through the dimensionless ratios T/μ and g = λ/μ3 with λ the't Hooft coupling. We determine the critical T/μ of the confinement transition for couplings g that span three orders of magnitude, to connect weak-coupling perturbative calculations and large-N dual supergravity predictions in the strong-coupling limit. Analyzing multiple lattice sizes up to Nτ = 24 and numbers of colors up to N = 16 allows initial checks of the large-N continuum limit

THREE DIMENSIONAL MEASUREMENT OF THE GEOMETRY OF THE HUMAN MOTION APPARATUS

INTRODUCTION: This work is part of a project of the Department for Sports Medicine to calculate the internal stresses arising when jumping from a squat position. The goal of the project is to facilitate individual calculations by establishing a biomechanical model whose parameters are the major anatomical-geometrical and physiological quantities, gained by electromyogram (EMG) and radiological measurement. Procedures for acquiring the latter data are described here. METHODS: As the study did not involve pathologies, ionizing radiation was ruled out, and magnetic resonance imaging (MRI) was used. The biomechanical model required geometrical parameters from joint positions beyond those occurring during the squat-vault, so the Siemens Magnetom Open device was chosen. It has the disadvantage of relatively low magnetic field strength (0.2 T), but allows for almost unlimited movement in the table plane. Different measurement parameters were evaluated. As the length of the field of view was about 25 cm, the different joints had to be scanned separately. A positioning table was used to serve three purposes: 1. Positioning with defined joint angles, so the morphology could be related to the EMG measurements. 2. Exertion of force, to measure the geometry of muscles and tendons under strain. 3. Placement of markers with high MRI contrast, to relate the relative position of the scans of the different joints. [delete line space]. The evaluation of the images was done using the ‘Tübinger Medstation’ software developed by the Department of Computer Science at the University of Tübingen. RESULTS: Although the use of T2 weighted sequences resulted in better soft tissue contrast, the T1 weighted spin echo sequence was preferred because of shorter acquisition time, which was an important factor because measurements had to be made under strain. Bones and tendons, with their low hydrogen content, produce weak signals in MRI and thus contrast with the adjacent soft tissue. Even shorter acquisition times by use of a gradient sequence were ruled out because of their low signal/noise ratio, which rendered the fascies undetectable. Automatic segmentation of these fascies is extremely hard to achieve. The ‘Medstation’ software was used to extract coordinates of muscle and tendon insertions by hand and combine them in a common frame of reference. CONCLUSIONS: A procedure has been established to extract the geometrical data of muscles, tendons and osseous structures important for the biomechanical model. For this model, extended muscle and tendon insertions have to be reduced to a point by calculation of the center of mass of the insertion area. A table for the positioning of the probationer enabled positioning with reproducible joint angles under exertion of strain. To define the relative position of different scans a screen of markers was integrated into this plate

Linear Sigma EFT for Nearly Conformal Gauge Theories

We construct a generalized linear sigma model as an effective field theory (EFT) to describe nearly conformal gauge theories at low energies. The work is motivated by recent lattice studies of gauge theories near the conformal window, which have shown that the lightest flavor-singlet scalar state in the spectrum ($\sigma$) can be much lighter than the vector state ($\rho$) and nearly degenerate with the PNGBs ($\pi$) over a large range of quark masses. The EFT incorporates this feature. We highlight the crucial role played by the terms in the potential that explicitly break chiral symmetry. The explicit breaking can be large enough so that a limited set of additional terms in the potential can no longer be neglected, with the EFT still weakly coupled in this new range. The additional terms contribute importantly to the scalar and pion masses. In particular, they relax the inequality $M_{\sigma}^2 \ge 3 M_{\pi}^2$, allowing for consistency with current lattice data.Comment: 9 pages, 1 figure, published versio

Lattice study of ChPT beyond QCD

We describe initial results by the Lattice Strong Dynamics (LSD) collaboration of a study into the variation of chiral properties of chiral properties of SU(3) Yang-Mills gauge theory as the number of massless flavors changes from $N_f = 2$ to $N_f = 6$, with a focus on the use of chiral perturbation theory.Comment: 9 pages, 3 figures. Presented at the 6th International Workshop on Chiral Dynamics, University of Bern, Switzerland, July 6-10 200

Large-N limit of two-dimensional Yang-Mills theory with four supercharges

We study the two-dimensional Yang-Mills theory with four supercharges in the large-N limit. By using thermal boundary conditions, we analyze the internal energy and the distribution of scalars. We compare their behavior to the maximally supersymmetric case with sixteen supercharges, which is known to admit a holographic interpretation. Our lattice results for the scalar distribution show no visible dependence on N and the energy at strong coupling appears independent of temperature

Parity Doubling and the S Parameter Below the Conformal Window

We describe a lattice simulation of the masses and decay constants of the lowest-lying vector and axial resonances, and the electroweak S parameter, in an SU(3) gauge theory with $N_f = 2$ and 6 fermions in the fundamental representation. The spectrum becomes more parity doubled and the S parameter per electroweak doublet decreases when $N_f$ is increased from 2 to 6, motivating study of these trends as $N_f$ is increased further, toward the critical value for transition from confinement to infrared conformality.Comment: 4 pages, 5 figures; to be submitted to PR

Toward TeV Conformality

We study the chiral condensate $$ for an SU(3) gauge theory with $N_f$ massless Dirac fermions in the fundamental representation when $N_f$ is increased from 2 to 6. For $N_f=2$, our lattice simulations of $<\bar{\psi} \psi >/F^3$, where $F$ is the Nambu-Goldstone-boson decay constant, agree with the measured QCD value. For $N_f = 6$, this ratio shows significant enhancement, presaging an even larger enhancement anticipated as $N_f$ increases further, toward the critical value for transition from confinement to infrared conformality.Comment: 4 pages, 4 figures. v2: revised version for PR

Specific mutations in the D1–D2 linker region of VCP/p97 enhance ATPase activity and confer resistance to VCP inhibitors

A grant from the One-University Open Access Fund at the University of Kansas was used to defray the author's publication fees in this Open Access journal. The Open Access Fund, administered by librarians from the KU, KU Law, and KUMC libraries, is made possible by contributions from the offices of KU Provost, KU Vice Chancellor for Research & Graduate Studies, and KUMC Vice Chancellor for Research. For more information about the Open Access Fund, please see http://library.kumc.edu/authors-fund.xml.Valosin-containing protein (VCP), together with several partner proteins, extracts ubiquitinated client proteins from E3 ligase complex and facilitates their degradation through ubiquitin–proteasome system. Therefore, it plays an important role in regulating protein quality control and various cellular pathways. Recent studies also identified VCP as a lineage-specific essential gene in ovarian cancer. An orally bioavailable VCP inhibitor, CB-5083, is currently in Phase I clinical trials because it shows therapeutic effects in multiple tumor xenograft models. However, the mechanism of resistance to CB-5083 is unknown. Here, we characterized molecular mechanism of resistance to CB-5083. Using incremental exposure to CB-5083, we established CB-5083-resistant ovarian cancer cells that showed five- to six-fold resistance in vitro compared with parental cells. Genomic and complementary DNA sequencing of the VCP coding region revealed a pattern of co-selected mutations: (1) missense mutations at codon 470 in one copy resulting in increased ATPase activity and (2) nonsense or frameshift mutations at codon 606 or codon 616 in another copy causing the loss of allele-specific expression. Unbiased molecular docking studies showed codon 470 as a putative binding site for CB-5083. Furthermore, the analysis of somatic mutations in cancer genomes from the Cancer Genome Atlas (TCGA) indicated that codon 616 contains hotspot mutations in VCP. Thus, identification of these mutations associated with in vitro resistance to VCP inhibitors may be useful as potential theranostic markers while screening for patients to enroll in clinical trials. VCP has emerged as a viable therapeutic target for several cancer types, and therefore targeting such hyperactive VCP mutants should aid in improving the therapeutic outcome in cancer patients