Muscle Fatigue During Cardiopulmonary Resuscitation Chest Compressions

The performance of Cardio Pulmonary Resuscitation (CPR) chest compressions on a patient provide critical blood flow and oxygen delivery to the heart and brain. The objective of this study was to establish the relationship between the rate of muscle fatigue and chest compression performance. It was hypothesized that if performance of chest compressions cause fatigue after five minutes, then the rate of muscle fatigue will be indicated through surface electromyography (sEMG) measurements. Four participants (M=2, F=2) volunteered to perform chest compressions on a CPR mannequin. sEMG electrodes were placed on the participants’ dominant limb anterior deltoid muscle to capture muscle activity while performing chest compressions. Each participant completed four sets of CPR chest compressions with a two minute rest period between sets. Data was analyzed through the iWrox LabScribe™ software. The absolute interval, root mean square, and minimum and maximum amplitudes for each signal were collected for data analysis. The mean amplitude percent decline was calculated for each set of chest compressions in three-minute intervals for each participant. Examination of the rate of decline between subjects, indicating muscle fatigue was evident. The hypothesis was therefore accepted; there was convincing muscle fatigue shown through sEMG measurements while CPR chest compressions were performed. If the study was to be replicated, the author recommends that the study involve more participants to confirm the established data

Low-mode averaging for baryon correlation functions

The low-mode averaging technique is a powerful tool for reducing large fluctuations in correlation functions due to low-mode eigenvalues of the Dirac operator. In this work we propose a generalization to baryons and test our method on two-point correlation functions of left-handed nucleons, computed with quenched Neuberger fermions on a lattice with extension L=1.5 fm. We show that the statistical fluctuations can be reduced and the baryon signal significantly improved.Comment: 6 pages, talk presented at the XXIIIrd International Symposium on Lattice Field Theory, 25-30 July 2005, Trinity College, Dublin, Irelan

On the spectral density of the Wilson operator

We summarize our recent determination [1] of the spectral density of the Wilson operator in the p-regime of Wilson chiral perturbation theory. We discuss the range of validity of our formula and a possible extension to our computation in order to better understand the behaviour of the spectral density in a finite volume close to the threshold.Comment: 7 pages, 2 figures, Proceedings for the XXIX International Symposium on Lattice Field Theor

Corrections to the Banks-Casher relation with Wilson quarks

The Banks-Casher relation links the spectral density of the Dirac operator with the existence of a chiral condensate and spontaneous breaking of chiral symmetry. This relation receives corrections from a finite value of the quark mass, a finite space-time volume and, if evaluated on a discrete lattice, from the finite value of the lattice spacing a. We present a status report of a determination of these corrections for Wilson quarks.Comment: 6 pages, 4 figures, Chiral Dynamics 2012 proceedin

Wilson fermions in the epsilon regime

We extend the epsilon-expansion of continuum chiral perturbation theory to nonzero lattice spacing in the framework of Wilson Chiral Perturbation Theory. We distinguish various regimes by defining the relative power counting of the quark mass m and the lattice spacing a. We observe that for m ~ a Lambda^2_QCD, the explicit breaking of chiral symmetry in Wilson fermions is still driven by the quark mass and lattice corrections are highly suppressed. The lattice spacing effects become more pronounced for smaller quark masses and may lead to non-trivial corrections of the continuum results at next-to-leading order. We compute these corrections for standard current and density correlation functions. A fit to lattice data shows that these corrections are small, as expected.Comment: Talk presented at the XXVII International Symposium on Lattice Field Theory, July 26-31, 2009, Peking University, Beijing, China; 7 pages, 1 figur

Thermal operators and cluster topology in q-state Potts Model

We discuss a new class of identities between correlation functions which arise from a local Z_2 invariance of the partition function of the q-state Potts model on general graphs or lattices. Their common feature is to relate the thermal operators of the Potts model to some topological properties of the Fortuin-Kasteleyn clusters. In particular it turns out that any even correlation function can be expressed in terms of observables which probe the linking properties of these clusters. This generalises a class of analogous relations recently found in the Ising model.Comment: 6 pages, latex, enlarged version, accepted for publication in Journal of Physics

Finite-size scaling of heavy-light mesons

We study the finite-size scaling of heavy-light mesons in the static limit. The most relevant effects are due to the pseudo-Goldstone boson cloud. In the HMChPT framework we compute two-point functions of left current densitities as well as pseudoscalar densitites for the cases in which some or all of them lay in the epsilon-regime. As expected, finite volume dependence turns out to be significant in this regime and can be predicted in the effective theory in terms of the infinite-volume low-energy couplings. These results might be relevant for extraction of heavy-light meson properties from lattice simulations.Comment: 7 pages, 2 figures, Contributed to 27th International Symposium on Lattice Field Theory, Beijing, China, 26 - 31 Jul 200

The epsilon regime with Wilson fermions

We study the impact of explicit chiral symmetry breaking of Wilson fermions on mesonic correlators in the epsilon-regime using Wilson chiral perturbation theory (WChPT). We generalize the epsilon-expansion of continuum ChPT to nonzero lattice spacings for various quark mass regimes. It turns out that the corrections due to a nonzero lattice spacing are highly suppressed for typical quark masses of the order aLambda_QCD^2. The lattice spacing effects become more pronounced for smaller quark masses and lead to non-trivial corrections of the continuum ChPT results at next-to-leading order. We compute these corrections for the standard current and density correlation functions. A fit to lattice data shows that these corrections are small, as expected.Comment: 29 pages, 2 figure