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34 result(s) for "Puckett, Andrew"
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Investigating introductory astronomy students’ perceived impacts from participation in course-based undergraduate research experiences
[This paper is part of the Focused Collection on Astronomy Education Research.] This study investigates students' perceived impacts regarding their participation in course-based undergraduate research experiences (CUREs) in astronomy. Each research experience adopted one or more projects from the Research Based Science Education for Undergraduates (RBSEU) curriculum, which teaches analysis of astronomical data coming from various national observatories. Participating students were enrolled in introductory astronomy courses at one of four universities using the curriculum. They were invited to respond to several instruments, including surveys (N = 199), essays (N = 94), and interviews (N = 19). Each university implemented the curriculum differently with respect to content covered, length of instruction, and whether students'research results were contributed to the astronomical community. We found that participation in all versions of the curriculum had the potential to significantly increase students' perceived confidence participating in science. However, participation in experiences wherein results were contributed to the scientific community more often led to students' nuanced perceptions of science processes, including increased understanding of the role of analysis and the utility of scientific communities and collaborations. We frame our study according to a pathway model under study by discipline-based education researchers of CUREs and explore our findings' connections with psychological theories.
The 6 GeV TMD Program at Jefferson Lab
The study of the transverse momentum dependent parton distributions (TMDs) of the nucleon in semi-inclusive deep-inelastic scattering (SIDIS) has emerged as one of the major physics motivations driving the experimental program using the upgraded 11 GeV electron beam at Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF). The accelerator construction phase of the CEBAF upgrade is essentially complete and commissioning of the accelerator has begun as of April, 2014. As the new era of CEBAF operations begins, it is appropriate to review the body of published and forthcoming results on TMDs from the 6 GeV era of CEBAF operations, discuss what has been learned, and discuss the key challenges and opportunities for the 11 GeV SIDIS program of CEBAF.
50 Years of quantum chromodynamics
Quantum Chromodynamics, the theory of quarks and gluons, whose interactions can be described by a local SU(3) gauge symmetry with charges called “color quantum numbers”, is reviewed; the goal of this review is to provide advanced Ph.D. students a comprehensive handbook, helpful for their research. When QCD was “discovered” 50 years ago, the idea that quarks could exist, but not be observed, left most physicists unconvinced. Then, with the discovery of charmonium in 1974 and the explanation of its excited states using the Cornell potential, consisting of the sum of a Coulomb-like attraction and a long range linear confining potential, the theory was suddenly widely accepted. This paradigm shift is now referred to as the November revolution . It had been anticipated by the observation of scaling in deep inelastic scattering, and was followed by the discovery of gluons in three-jet events. The parameters of QCD include the running coupling constant, α s ( Q 2 ) , that varies with the energy scale Q 2 characterising the interaction, and six quark masses. QCD cannot be solved analytically, at least not yet, and the large value of α s at low momentum transfers limits perturbative calculations to the high-energy region where Q 2 ≫ Λ QCD 2 ≃ (250 MeV) 2 . Lattice QCD (LQCD), numerical calculations on a discretized space-time lattice, is discussed in detail, the dynamics of the QCD vacuum is visualized, and the expected spectra of mesons and baryons are displayed. Progress in lattice calculations of the structure of nucleons and of quantities related to the phase diagram of dense and hot (or cold) hadronic matter are reviewed. Methods and examples of how to calculate hadronic corrections to weak matrix elements on a lattice are outlined. The wide variety of analytical approximations currently in use, and the accuracy of these approximations, are reviewed. These methods range from the Bethe–Salpeter, Dyson–Schwinger coupled relativistic equations, which are formulated in both Minkowski or Euclidean spaces, to expansions of multi-quark states in a set of basis functions using light-front coordinates, to the AdS/QCD method that imbeds 4-dimensional QCD in a 5-dimensional deSitter space, allowing confinement and spontaneous chiral symmetry breaking to be described in a novel way. Models that assume the number of colors is very large, i.e. make use of the large N c -limit, give unique insights. Many other techniques that are tailored to specific problems, such as perturbative expansions for high energy scattering or approximate calculations using the operator product expansion are discussed. The very powerful effective field theory techniques that are successful for low energy nuclear systems (chiral effective theory), or for non-relativistic systems involving heavy quarks, or the treatment of gluon exchanges between energetic, collinear partons encountered in jets, are discussed. The spectroscopy of mesons and baryons has played an important historical role in the development of QCD. The famous X,Y,Z states – and the discovery of pentaquarks – have revolutionized hadron spectroscopy; their status and interpretation are reviewed as well as recent progress in the identification of glueballs and hybrids in light-meson spectroscopy. These exotic states add to the spectrum of expected q q ¯ mesons and qqq baryons. The progress in understanding excitations of light and heavy baryons is discussed. The nucleon as the lightest baryon is discussed extensively, its form factors, its partonic structure and the status of the attempt to determine a three-dimensional picture of the parton distribution. An experimental program to study the phase diagram of QCD at high temperature and density started with fixed target experiments in various laboratories in the second half of the 1980s, and then, in this century, with colliders. QCD thermodynamics at high temperature became accessible to LQCD, and numerical results on chiral and deconfinement transitions and properties of the deconfined and chirally restored form of strongly interacting matter, called the Quark–Gluon Plasma (QGP), have become very precise by now. These results can now be confronted with experimental data that are sensitive to the nature of the phase transition. There is clear evidence that the QGP phase is created. This phase of QCD matter can already be characterized by some properties that indicate, within a temperature range of a few times the pseudocritical temperature, the medium behaves like a near ideal liquid. Experimental observables are presented that demonstrate deconfinement. High and ultrahigh density QCD matter at moderate and low temperatures shows interesting features and new phases that are of astrophysical relevance. They are reviewed here and some of the astrophysical implications are discussed. Perturbative QCD and methods to describe the different aspects of scattering processes are discussed. The primary parton–parton scattering in a collision is calculated in perturbative QCD with increasing complexity. The radiation of soft gluons can spoil the perturbative convergence, this can be cured by resummation techniques, which are also described here. Realistic descriptions of QCD scattering events need to model the cascade of quark and gluon splittings until hadron formation sets in, which is done by parton showers. The full event simulation can be performed with Monte Carlo event generators, which simulate the full chain from the hard interaction to the hadronic final states, including the modelling of non-perturbative components. The contribution of the LEP experiments (and of earlier collider experiments) to the study of jets is reviewed. Correlations between jets and the shape of jets had allowed the collaborations to determine the “color factors” – invariants of the SU(3) color group governing the strength of quark–gluon and gluon–gluon interactions. The calculated jet production rates (using perturbative QCD) are shown to agree precisely with data, for jet energies spanning more than five orders of magnitude. The production of jets recoiling against a vector boson, W ± or Z , is shown to be well understood. The discovery of the Higgs boson was certainly an important milestone in the development of high-energy physics. The couplings of the Higgs boson to massive vector bosons and fermions that have been measured so far support its interpretation as mass-generating boson as predicted by the Standard Model. The study of the Higgs boson recoiling against hadronic jets (without or with heavy flavors) or against vector bosons is also highlighted. Apart from the description of hard interactions taking place at high energies, the understanding of “soft QCD” is also very important. In this respect, Pomeron – and Odderon – exchange, soft and hard diffraction are discussed. Weak decays of quarks and leptons, the quark mixing matrix and the anomalous magnetic moment of the muon are processes which are governed by weak interactions. However, corrections by strong interactions are important, and these are reviewed. As the measured values are incompatible with (most of) the predictions, the question arises: are these discrepancies first hints for New Physics beyond the Standard Model? This volume concludes with a description of future facilities or important upgrades of existing facilities which improve their luminosity by orders of magnitude. The best is yet to come!
Correlating Climate Conditions With Pseudomonas aeruginosa Prevalence in Diabetic Foot Infections Within the United States
Abstract Background The 2023 “International Working Group on the Diabetic Foot/Infectious Disease Society of America Guidelines on the Diagnosis and Treatment of Diabetes-Related Foot Infections” (DFIs) provides recommendations for Pseudomonas coverage based on the climate region. Methods This was a retrospective national study of veterans between 1/1/2010 and 3/23/2024 with diabetes mellitus and a culture below the malleolus wound. Prevalence of Pseudomonas was categorized based on climate zones according to the International Energy Conservation Code. Multivariable logistic regression was used to determine odds ratios and 97.5% CIs. Results The prevalence of Pseudomonas significantly varied between US climates. Pseudomonas was most prevalent within the Hot Humid climate, where it was isolated in 11.6% of DFI cultures. Pseudomonas was least prevalent within the Very Cold climate, where it was isolated in 6.2% of cultures. In the multivariable logistic regression model, hot and humid climates were associated with an odds of P. aeruginosa of 1.92 (97.5% CI, 1.69–2.20), a hot, dry climate was associated with an odds of 1.65 (97.5% CI, 1.44–1.90), and a humid climate was associated with an odds of 1.65 (97.5% CI, 1.45–1.89). A lower Charlson Comorbidity Index, inpatient admission, recent antipseudomonal antibiotic use, and swabs were less likely to have Pseudomonas. Recent admission increased the odds of P. aeruginosa (odds ratio [OR], 1.34; 97.5% CI, 1.27–1.41). History of P. aeruginosa was associated with an increase in P. aeruginosa (OR, 8.90; 97.5% CI, 8.29–9.56). Conclusions The prevalence of DFI organisms varies within different US climates. Utilization of local climate information may allow for more accurate and targeted empiric antibiotic selection when treating DFIs. The prevalence of Pseudomonas aeruginosa varies within different United States climate designations. Further studies are needed to determine a threshold for which empirical Pseudomonas treatment should be considered when treating diabetes-related foot infections.
50 Years of quantum chromodynamics
Quantum Chromodynamics, the theory of quarks and gluons, whose interactions can be described by a local SU(3) gauge symmetry with charges called “color quantum numbers”, is reviewed; the goal of this review is to provide advanced Ph.D. students a comprehensive handbook, helpful for their research. When QCD was “discovered” 50 years ago, the idea that quarks could exist, but not be observed, left most physicists unconvinced. Then, with the discovery of charmonium in 1974 and the explanation of its excited states using the Cornell potential, consisting of the sum of a Coulomb-like attraction and a long range linear confining potential, the theory was suddenly widely accepted. This paradigm shift is now referred to as the November revolution. It had been anticipated by the observation of scaling in deep inelastic scattering, and was followed by the discovery of gluons in three-jet events.