The Millikan Oil Drop Experiment: A Simulation Suitable For Classroom Use

Due to advancements in computing techniques it has become possible to extend the accessibility of physics experiments across the physics curriculum by means of computational simulations. The widespread availability of computers in modern classrooms provides virtual access to hands-on physics, chemistry, and biology experiments, among others. Here, specifically, we consider Robert Millikan’s famous oil drop experiment. This experiment requires equipment that can be dangerous and expensive. A more practical approach is achieved via a computer simulation, a useful and a universally available alternative. The goal is to encourage scientific thinking, literacy, and innovation while promoting a free network of academic tools. Here we present a simulation that allows the user to carry out Millikan’s ingenious experiment by measuring the velocities of oil drops as they are influenced by an electric field. This is repeated until enough data is produced to deduce the charge of the electron. The simulation provides a clean and simple user interface, allowing for realistic interactions within a computational environment. For best results, a basic understanding of the theory and experimental procedure is valuable. We use Easy Java Simulations as the programming environment to carry out the simulation presented here

The Nucleon-Core Interaction: a Nuclear Physics Simulation Suitable for Classroom Use

The orbits of a nucleon and its respective parent nucleus about their common center of mass are simulated in an effort to provide a pedagogical approach to the understanding of the structure of atomic nuclei. The nuclear exercise is treated by solving the problem with an effective force on the system’s reduced mass. The potential governing the mean field is modeled by the Woods-Saxon form-factor with parameters that enable it to describe experimental findings. The Woods-Saxon potential is preferred over the infinite well and harmonic oscillator methods because both require infinite separation energies of the nucleons. The simulation is created using Easy Java Simulations (EJS) which is part of the Open Source Physics project and a MATLAB version (compatible with Octave) is included in the Appendix

Mapping Low-Density Intergalactic Gas: a Third Helium Lyman-alpha Forest

We present a new HST/STIS spectrum of the z=3.18 quasar PKS 1935-692 and summarize the spectral features shortwards of 304A in the rest frame likely to be caused by foreground HeII Lyman-alpha absorption. In accord with previous results on two other quasars at similar redshifts, we demonstrate a correlation with the HI Lyman-alpha forest absorption, and show that much of the helium absorption is caused by a comparable quantity of more diffuse gas with Omega~0.01, that is not detected in HI. The helium ionization zone around the quasar is detected as well as a void seen in both HI and HeII. The properties of the absorption are in broad agreement with those of the other quasars and with models of the protogalactic gas distribution and ionization at this redshift.Comment: 17 pages including 5 figures. As accepted for publication in The Astronomical Journal (minor revisions

Workload Assessment for Community Corrections Staffing for the Washington Department of Corrections

About 20 years ago, the Washington State Department of Corrections (WADOC) participated in two workload evaluations with the aim of identifying key tasks associated with community corrections work and the time to complete such tasks, and utilized these data to inform the amount of resources needed to carry out the responsibilities of the Community Corrections Division (CCD). Those evaluations set a precedent for how WADOC made informed decisions that shaped practice and policy for staffing. Then, in the fall of 2021, WADOC contracted with Westat, Inc. to conduct an updated, full-scale workload assessment of staff members who carry out the responsibilities of the CCD

Senior Recital: Ladarius Young, Clarinet; Freda Hogan, Clarinet; Benjamin Sanetra, Clarinet; Lu Witzig, Piano; March 2, 2022

Kemp Recital Hall March 2, 2022 Wednesday Evening 7:00 p.m

Worst-Case-Optimal Similarity Joins on Graph Databases

© ACM 2024. This is the author's version of the work (accepted manuscript or postprint). It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in Proceedings of the ACM on Management of Data, https:// doi.org/10.1145/3639294[Absctract]: We extend the concept of worst-case optimal equijoins in graph databases to the case where some nodes are required to be within the k-nearest neighbors (kNN) of others under some similarity function. We model the problem by superimposing the database graph with the kNN graph and show that a variant of Leapfrog TrieJoin (LTJ) implemented over a compact data structure called the Ring can be seamlessly extended to integrate similarity clauses with the equijoins in the LTJ query process, retaining worst-case optimality in many relevant cases. Our experiments on a benchmark that combines Wikidata and IMGpedia show that our enhanced LTJ algorithm outperforms by a considerable margin a baseline that first applies classic LTJ and then completes the query by applying the similarity predicates. The difference is more pronounced on queries where the similarity clauses are more densely connected to the query, becoming of an order of magnitude in some cases.Funded by ANID – Millennium Science Initiative Program – Code ICN17_002. A.G. is funded in part by MCIN/AEI/10.13039/5011000-11033: grant PID2020-114635RB-I00 (EXTRACompact); by MCIN/A-EI/10.13039/501100011033 and EU/ERDF "A way of making Europe": PID2022-141027NBC21 (EARTHDL); by MCIN/AEI/10.13039/501100011033 and “Next-GenerationEU”/ PRTR: grants TED2021-129245B-C21 (PLAGEMIS), PDC2021-120917-C21 (SIGTRANS) and by GAIN/Xunta de Galicia: GRC: grants ED431C 2021/53, and CIGUS 2023-2026. A.H. was funded in part by Fondecyt Grant 1221926. G.N. was funded in part by Fondecyt Grant 1-230755. J.R. was funded in part by Fondecyt Grant 1221799.Chile. Agencia Nacional de Investigación y Desarrollo; ICN17_002Xunta de Galicia; ED431C 2021/53Xunta de Galicia; CIGUS 2023-2026Chile. Fondo Nacional de Desarrollo Científico y Tecnológico (Fondecyt); 1-230755Chile. Fondo Nacional de Desarrollo Científico y Tecnológico (Fondecyt); 1221926Chile. Fondo Nacional de Desarrollo Científico y Tecnológico (Fondecyt); 122179