About

Molly Clark is an Assistant Director in the Department of Electrical and Computer Engineering at Boston University College of Engineering. Her responsibilities include supervising academic teams, overseeing course scheduling and academic operations management of the MS program, and providing academic program support for PhD and undergraduate programs. She also manages data collection related to enrollment trends and course evaluations. Additionally, Molly Clark offers student advising and support, particularly for escalated student concerns related to program requirements, curriculum issues, and administrative matters.

Research topics

• Physics
• Particle physics
• Mathematical physics
• Computer Science
• Mechanics
• Materials science
• Composite material
• Quantum mechanics
• Mathematical analysis

Selected publications

• Movement profile influences systemic stress and biomechanical resilience to high training load exposure

  Carolina Digital Repository (University of North Carolina at Chapel Hill) · 2024-03-01 · 1 citations

  articleOpen access
  PublisherOA PDFDOI

• Detailed analysis of excited-state systematics in a lattice QCD calculation of gA

  eScholarship (California Digital Library) · 2023-06-16

  articleOpen access

  Excited state contamination remains one of the most challenging sources of systematic uncertainty to control in lattice QCD calculations of nucleon matrix elements and form factors: early time separations are contaminated by excited states and late times suffer from an exponentially bad signal-to-noise problem. High-statistics calculations at large time separations 1 fm are commonly used to combat these issues. In this work, focusing on gA, we explore the alternative strategy of utilizing a large number of relatively low-statistics calculations at short to medium time separations (0.2-1 fm), combined with a multistate analysis. On an ensemble with a pion mass of approximately 310 MeV and a lattice spacing of approximately 0.09 fm, we find this provides a more robust and economical method of quantifying and controlling the excited state systematic uncertainty. A quantitative separation of various types of excited states enables the identification of the transition matrix elements as the dominant contamination. The excited state contamination of the Feynman-Hellmann correlation function is found to reduce to the 1% level at approximately 1 fm while, for the more standard three-point functions, this does not occur until after 2 fm. Critical to our findings is the use of a global minimization, rather than fixing the spectrum from the two-point functions and using them as input to the three-point analysis. We find that the ground state parameters determined in such a global analysis are stable against variations in the excited state model, the number of excited states, and the truncation of early-time or late-time numerical data.

  PublisherOA PDFDOI

• Nucleon axial coupling from Lattice QCD

  OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 2023-06-16 · 2 citations

  articleOpen access

  We present state-of-the-art results from a lattice QCD calculation of the nucleon axial coupling, gA, using Möbius Domain-Wall fermions solved on the dynamical Nf = 2 + 1 + 1 HISQ ensembles after they are smeared using the gradient-flow algorithm. Relevant three-point correlation functions are calculated using a method inspired by the Feynman-Hellmann theorem, and demonstrate significant improvement in signal for fixed stochastic samples. The calculation is performed at five pion masses of mπ ∼ {400, 350, 310, 220, 130} MeV, three lattice spacings of a ∼ {0.15, 0.12, 0.09} fm, and we do a dedicated volume study with mπL ∼ {3.22, 4.29, 5.36}. Control over all relevant sources of systematic uncertainty are demonstrated and quantified. We achieve a preliminary value of gA = 1.285(17), with a relative uncertainty of 1.33%.

  PublisherOA PDFDOI

• Scale setting the Möbius domain wall fermion on gradient-flowed HISQ action using the omega baryon mass and the gradient-flow scales t0 and w0

  2023-06-16

  articleOpen access

  We report on a subpercent scale determination using the omega baryon mass and gradient-flow methods. The calculations are performed on 22 ensembles of Nf=2+1+1 highly improved, rooted staggered sea-quark configurations generated by the MILC and CalLat Collaborations. The valence quark action used is Möbius domain wall fermions solved on these configurations after a gradient-flow smearing is applied with a flowtime of tgf=1 in lattice units. The ensembles span four lattice spacings in the range 0.06a0.15 fm, six pion masses in the range 130mπ400 MeV and multiple lattice volumes. On each ensemble, the gradient-flow scales t0/a2 and w0/a and the omega baryon mass amω are computed. The dimensionless product of these quantities is then extrapolated to the continuum and infinite volume limits and interpolated to the physical light, strange and charm quark mass point in the isospin limit, resulting in the determination of t0=0.1422(14) fm and w0=0.1709(11) fm with all sources of statistical and systematic uncertainty accounted for. The dominant uncertainty in both results is the stochastic uncertainty, though for t0 there are comparable continuum extrapolation uncertainties. For w0, there is a clear path for a few-per-mille uncertainty just through improved stochastic precision, as recently obtained by the Budapest-Marseille-Wuppertal Collaboration.

  OA PDFDOI

• FK /Fπ from Möbius domain-wall fermions solved on gradient-flowed HISQ ensembles

  eScholarship (California Digital Library) · 2023-06-16

  articleOpen access

  We report the results of a lattice quantum chromodynamics calculation of FK/Fπ using Möbius domain-wall fermions computed on gradient-flowed Nf=2+1+1 highly improved staggered quark (HISQ) ensembles. The calculation is performed with five values of the pion mass ranging from 130 400 MeV, four lattice spacings of a∼0.15, 0.12, 0.09 and 0.06 fm and multiple values of the lattice volume. The interpolation/extrapolation to the physical pion and kaon mass point, the continuum, and infinite volume limits are performed with a variety of different extrapolation functions utilizing both the relevant mixed-action effective field theory expressions as well as discretization-enhanced continuum chiral perturbation theory formulas. We find that the a∼0.06 fm ensemble is helpful, but not necessary to achieve a subpercent determination of FK/Fπ. We also include an estimate of the strong isospin breaking corrections and arrive at a final result of FK+/Fπ+=1.1942(45) with all sources of statistical and systematic uncertainty included. This is consistent with the Flavour Lattice Averaging Group average value, providing an important benchmark for our lattice action. Combining our result with experimental measurements of the pion and kaon leptonic decays leads to a determination of |Vus|/|Vud|=0.2311(10).

  PublisherOA PDFDOI

• Application Experiences on a GPU-Accelerated Arm-based HPC Testbed

  2023-02-03 · 8 citations

  articleOpen access

  This paper assesses and reports the experience of ten teams working to port, validate, and benchmark several High Performance Computing applications on a novel GPU-accelerated Arm testbed system. The testbed consists of eight NVIDIA Arm HPC Developer Kit systems, each one equipped with a server-class Arm CPU from Ampere Computing and two data center GPUs from NVIDIA Corp. The systems are connected together using InfiniBand interconnect. The selected applications and mini-apps are written using several programming languages and use multiple accelerator-based programming models for GPUs such as CUDA, OpenACC, and OpenMP offloading. Working on application porting requires a robust and easy-to-access programming environment, including a variety of compilers and optimized scientific libraries. The goal of this work is to evaluate platform readiness and assess the effort required from developers to deploy well-established scientific workloads on current and future generation Arm-based GPU-accelerated HPC systems. The reported case studies demonstrate that the current level of maturity and diversity of software and tools is already adequate for large-scale production deployments.

  PublisherOA PDFDOI

• Heavy Physics Contributions to Neutrinoless Double Beta Decay from QCD

  UNC Libraries · 2023-06-16 · 4 citations

  articleOpen access

  Observation of neutrinoless double beta decay, a lepton number violating process that has been proposed to clarify the nature of neutrino masses, has spawned an enormous world-wide experimental effort. Relating nuclear decay rates to high-energy, beyond the standard model (BSM) physics requires detailed knowledge of nonperturbative QCD effects. Using lattice QCD, we compute the necessary matrix elements of short-range operators, which arise due to heavy BSM mediators, that contribute to this decay via the leading order π-→π+ exchange diagrams. Utilizing our result and taking advantage of effective field theory methods will allow for model-independent calculations of the relevant two-nucleon decay, which may then be used as input for nuclear many-body calculations of the relevant experimental decays. Contributions from short-range operators may prove to be equally important to, or even more important than, those from long-range Majorana neutrino exchange.

  PublisherDOI

• Short Range Operator Contributions to 0νββ decay from LQCD

  UNC Libraries · 2023-06-16 · 1 citations

  articleOpen access

  The search for neutrinoless double beta decay of nuclei is believed to be one of the most promising means to search for new physics. Observation of this very rare nuclear process, which violates Lepton Number conservation, would imply the neutrino sector has a Majorana mass component and may also provide an explanation for the universe matter-antimatter asymmetry of the universe. In the case where a heavy intermediate particle is exchanged in this process, QCD contributions from short range interactions become relevant and the calculation of matrix elements with four-quark operators becomes necessary. In these proceedings we will discuss our current progress in the calculation of these four-quark operators from LQCD.

  PublisherDOI

• Accelerating Dedispersion Using Many-core Architectures

  The Astrophysical Journal Supplement Series · 2023-11-01 · 3 citations

  articleOpen access

  Abstract Astrophysical radio signals are excellent probes of extreme physical processes that emit them. However, to reach Earth, electromagnetic radiation passes through the ionized interstellar medium, introducing a frequency-dependent time delay (dispersion) to the emitted signal. Removing dispersion enables searches for transient signals like fast radio bursts or repeating signals from isolated pulsars or those in orbit around other compact objects. The sheer volume and high resolution of data that next-generation radio telescopes will produce require high-performance computing solutions and algorithms to be used in time-domain data-processing pipelines to extract scientifically valuable results in real time. This paper presents a state-of-the-art implementation of brute force incoherent dedispersion on NVIDIA graphics-processing units and on Intel and AMD central-processing units. We show that our implementation is 4× faster (8-bit 8192 channels input) than other available solutions, and we demonstrate, using 11 existing telescopes, that our implementation is at least 20× faster than real time. This work is part of the AstroAccelerate package.

  PublisherOA PDFDOI

• Self-reported concussion history among midwestern skiers and snowboarders

  Concussion · 2023-01-19 · 2 citations

  articleOpen access

  Aim: To assess the rate of self-reported concussion in midwestern skiers and snowboarders. Patients: Recreational skiers and snowboarders between the ages of 14 and 69 years during a single winter ski season (2020–2021) at a ski area in Wisconsin, USA. Methods: Survey study. Results: Among this survey population (n = 161), 9.32 and 19.25% reported one or more diagnosed concussion and suspected concussion respectively as a result of a skiing- or snowboarding-related incident. Skiers and snowboarders that self-identified as advanced, those who utilized terrain park features, and those that participated in freestyle competition had significantly higher self-reported rates of concussion. Conclusion: Self-reported concussion history indicates a concussion prevalence that is higher than expected based on previous studies. Participants reported significantly more suspected concussions than diagnosed concussions, indicating a possible issue with underreporting in this population.

  PublisherDOI

Frequent coauthors

• Bálint Joó

  Argonne National Laboratory

  246 shared

• André Walker-Loud

  Lawrence Berkeley National Laboratory

  237 shared

• Pavlos Vranas

  175 shared

• Enrico Rinaldi

  168 shared

• Chia Cheng Chang

  National Cheng Kung University Hospital

  163 shared

• Evan Berkowitz

  158 shared

• Amy Nicholson

  University of North Carolina at Chapel Hill

  155 shared

• Thorsten Kurth

  151 shared