Validating the Universe in a Box

Computer simulations of the formation and evolution of large scale structure in the universe are integral to the enterprise of modern cosmology. Establishing the reliability of these simulations has been extremely challenging, primarily because of epistemic opacity. In this setting, robustness analysis defined by requiring converging outputs from a diverse ensemble of simulations is insufficient to determine simulation validity. Instead, we propose an alternative path of structured code validation that applies eliminative reasoning to isolate and reduce possible sources of error, a potential path that is already being explored by some cosmologists.Comment: 13 pages. Accepted for publication in Philosophy of Science for the PSA2018 symposium proceedings issu

Prize Volatility and Presence or Absence of Anticipatory Sitmulus Signally Reward as Predictors of Electronic Game Machine Behaviour of Gamblers

This study investigated the effect of changes in prize volatility and presence or absence of an anticipatory stimulus signally reward on verbal ratings, playing behaviour, and biometric responses in casual and frequent electronic gaming machine (EGM) players. Biometric measurements of 129 participants were recorded while they played an actual EGM with money provided by the experimenters. However, only the data from 95 participants were analysed. Participants were first connected to biometric sensors to record their heart rate and galvanic skin responses, and completed a demographic questionnaire. All participants then played an EGM game for 10 minutes. After playing the EGM game, they either played the same EGM game or a different EGM game for another 10 minutes in accord with their experimental condition. The second game was characterized by one of four conditions, (a) low volatility, absence of anticipatory stimulus, (b) low volatility, presence of anticipatory stimulus, (c) high volatility, absence of anticipatory stimulus, and (d) high volatility, presence of anticipatory stimulus. After 20 minutes of EGM play, participants completed the Canadian Problem Gambling Index (CPGI; Ferris & Wynne, 2001). Statistical results revealed that the volatility condition had a significant effect on how quickly a player would bet. That is, players bet later in conditions with higher volatility. Furthermore, frequent players bet later than casual players. There was a significant interaction between volatility and player type, but the anticipatory stimulus condition was not found to have a significant effect on playing behaviour

A Bayesian partition modelling approach to resolve spatial variability in climate records from borehole temperature inversion

International audienceCollections of suitably chosen borehole profiles can be used to infer large-scale trends in ground-surface temperature (GST) histories for the past few hundred years. These reconstructions are based on a large database of carefully selected borehole temperature measurements from around the globe. Since non-climatic thermal influences are difficult to identify, representative temperature histories are derived by averaging individual reconstructions to minimize the influence of these perturbing factors. This may lead to three potentially important drawbacks: the net signal of non-climatic factors may not be zero, meaning that the average does not reflect the best estimate of past climate; the averaging over large areas restricts the useful amount of more local climate change information available; and the inversion methods used to reconstruct the past temperatures at each site must be mathematically identical and are therefore not necessarily best suited to all data sets. In this work, we avoid these issues by using a Bayesian partition model (BPM), which is computed using a trans-dimensional form of aMarkov chainMonte Carlo algorithm. This then allows the number and spatial distribution of different GST histories to be inferred from a given set of borehole data by partitioning the geographical area into discrete partitions. Profiles that are heavily influenced by non-climatic factors will be partitioned separately. Conversely, profiles with climatic information, which is consistent with neighbouring profiles, will then be inferred to lie in the same partition. The geographical extent of these partitions then leads to information on the regional extent of the climatic signal. In this study, three case studies are described using synthetic and real data. The first demonstrates that the Bayesian partition model method is able to correctly partition a suite of synthetic profiles according to the inferred GST history. In the second, more realistic case, a series of temperature profiles are calculated using surface air temperatures of a global climate model simulation. In the final case, 23 real boreholes from the United Kingdom, previously used for climatic reconstructions, are examined and the results compared with a local instrumental temperature series and the previous estimate derived from the same borehole data. The results indicate that the majority (17) of the 23 boreholes are unsuitable for climatic reconstruction purposes, at least without including other thermal processes in the forward model

Experimental verification of minima in excited long-range Rydberg states of Rb_2

Recent theoretical studies with alkali atoms A$^{\ast}$ excited to high Rydberg states predicted the existence of ultra long-range molecular bound states. Such excited dimers have large electric dipole moments which, in combination with their long radiative lifetimes, make them excellent candidates for manipulation in applications. This letter reports on experimental investigations of the self-broadening of Rb principal series lines, which revealed multiple satellites in the line wings. The positions of the satellites agree quantitatively with theoretically-predicted minima in the excited long-range Rydberg states of Rb$_2$.Comment: 3 figures, 5 pages in two-column forma

Student Shop Access and Inventory Control in the College of Architecture and Environmental Design Shops

The Cal Poly College of Architecture and Environmental Design shops, directed by David Kempken, give the opportunity for thousands of students to use the “Learn By Doing” philosophy and operate various machinery, tooling, and devices to complete projects inside and outside of the classroom. These students are able to check out tools and machinery to complete these projects on a weekly basis. This report will discuss the complexities and shortcomings of the current database system, FileMaker Pro, that is used for these transactions. The report will furthermore discuss the design and methodology of replacing this system with an improved integrated software or database designed specifically for this shop. Within this report is the senior project of IME fourth year students Chris Chen, Kevin Gallagher and Ryan Mattel. Two academic quarters have gone into the research, design, testing, analysis and recommendation of a proposed system using Microsoft Access to vastly improve the CAED shops. This proposed database will cut the current lost tooling of almost 350 tools per year, and drive down costs and processing time of each transaction by 50 percent. With the help of Technical Advisor Karla Carichner, and Project Sponsor David Kempken, the project is completed and a final proposal and product have been presented to the CAED shops based on the following research and analysis