Representing Network Trust and Using It to Improve Anonymous Communication

Motivated by the effectiveness of correlation attacks against Tor, the censorship arms race, and observations of malicious relays in Tor, we propose that Tor users capture their trust in network elements using probability distributions over the sets of elements observed by network adversaries. We present a modular system that allows users to efficiently and conveniently create such distributions and use them to improve their security. The major components of this system are (i) an ontology of network-element types that represents the main threats to and vulnerabilities of anonymous communication over Tor, (ii) a formal language that allows users to naturally express trust beliefs about network elements, and (iii) a conversion procedure that takes the ontology, public information about the network, and user beliefs written in the trust language and produce a Bayesian Belief Network that represents the probability distribution in a way that is concise and easily sampleable. We also present preliminary experimental results that show the distribution produced by our system can improve security when employed by users; further improvement is seen when the system is employed by both users and services.Comment: 24 pages; talk to be presented at HotPETs 201

Innovativeness and Innovation: Implications for the Renewable Materials Supply Chain

innovativeness, innovation, supply chain management, triple bottom line, corporate social responsibility, Agribusiness, Agricultural Finance, Demand and Price Analysis, Financial Economics, Q10, Q27, Q42, Q47,

Self-consistent predictions for LIER-like emission lines from post-AGB stars

Early type galaxies (ETGs) frequently show emission from warm ionized gas. These Low Ionization Emission Regions (LIERs) were originally attributed to a central, low-luminosity active galactic nuclei. However, the recent discovery of spatially-extended LIER emission suggests ionization by both a central source and an extended component that follows a stellar-like radial distribution. For passively-evolving galaxies with old stellar populations, hot post-Asymptotic Giant Branch (AGB) stars are the only viable extended source of ionizing photons. In this work, we present the first prediction of LIER-like emission from post-AGB stars that is based on fully self-consistent stellar evolution and photoionization models. We show that models where post-AGB stars are the dominant source of ionizing photons reproduce the nebular emission signatures observed in ETGs, including LIER-like emission line ratios in standard optical diagnostic diagrams and H$\alpha$ equivalent widths of order 0.1-3 angstroms. We test the sensitivity of LIER-like emission to the details of post-AGB models, including the mass loss efficiency and convective mixing efficiency, and show that line strengths are relatively insensitive to post-AGB timescale variations. Finally, we examine the UV-optical colors of the models and the stellar populations responsible for the UV-excess observed in some ETGs. We find that allowing as little as 3% of the HB population to be uniformly distributed to very hot temperatures (30,000 K) produces realistic UV colors for old, quiescent ETGs.Comment: ApJ accepted. 20 pages, 8 figure

Women in higher education: A brief report on stress during COVID-19

Higher education institutions have evolved into a more stressful environment. Women have been experiencing higher levels of stress than their male counterparts. With higher education adopting to the onset of the pandemic, this brief report studied women’s perceived stress in relation to perceived organizational and supervisory support, and age during times of crisis. In an era of social distancing, quarantines, and lockdowns, the findings suggest that women’s perceived stress is negatively related to age, perceived organizational support, and perceived supervisory support. Society as we once knew it pre-pandemic will never be the same. Higher education is inevitably going to have to manage the aftermath, a new normal that can only be as effective as the employees that help keep the organization running

Efficient Gravitational Wave Searches with Pulsar Timing Arrays using Hamiltonian Monte Carlo

Pulsar timing arrays (PTAs) detect low-frequency gravitational waves (GWs) by looking for correlated deviations in pulse arrival times. Current Bayesian searches use Markov Chain Monte Carlo (MCMC) methods, which struggle to sample the large number of parameters needed to model the PTA and GW signals. As the data span and number of pulsars increase, this problem will only worsen. An alternative Monte Carlo sampling method, Hamiltonian Monte Carlo (HMC), utilizes Hamiltonian dynamics to produce sample proposals informed by first-order gradients of the model likelihood. This in turn allows it to converge faster to high dimensional distributions. We implement HMC as an alternative sampling method in our search for an isotropic stochastic GW background, and show that this method produces equivalent statistical results to similar analyses run with standard MCMC techniques, while requiring 100-200 times fewer samples. We show that the speed of HMC sample generation scales as $\mathcal{O}(N_\mathrm{psr}^{5/4})$ where $N_\mathrm{psr}$ is the number of pulsars, compared to $\mathcal{O}(N_\mathrm{psr}^2)$ for MCMC methods. These factors offset the increased time required to generate a sample using HMC, demonstrating the value of adopting HMC techniques for PTAs.Comment: 9 pages, 5 figures, submitted to Physical Review

Development of a Flow Field for Testing a Boundary-Layer-Ingesting Propulsor

In order to test embedded-propulsor technology, modifications were required of the 8x6 Supersonic Wind tunnel at NASA Glenn Research Center. The extent of the modifications required that a new tunnel calibration be completed to generate a new calibration dataset and operational procedures for the tunnel, as well as to map the boundary layer on the raised floor. This report describes the propulsor inflow that was to be simulated, documents the tunnel modifications that were required, and conveys the results of the calibration test that was completed to measure the resulting flow properties

Vascular Alteration with Postural Change as Observed Using the Anterior Tibial Artery: A Pilot Study

Plantar fasciopathy and plantar fasciosis are common lower extremity conditions. Vascular health is an important aspect of plantar fascia health. Footwear choices are thought to influence lower extremity vascular flow, but how the anterior tibial artery is affected by purely postural changes over time is unknown. PURPOSE: To observe the anterior tibial artery vascular alterations over a ten-minute period after transitioning from a sitting to a standing position while barefoot. METHODS: Nine participants (age= 23.8yrs ±2.5, height= 176.0cm ±8.0, weight= 69.8kg ±10.2) were recruited from Brigham Young University for a single 30-minute visit. The participants had no previous lower extremity injuries within 6 months. The individual’s dominant foot arch height index was recorded, and the participant had a 3-lead ECG placed on their trunk. A Logic Fortis machine with an L8-18i probe was used to capture pulse wave (PW) images of the anterior tibial artery of the dominant foot. The participant sat barefoot on an elevated platform for five minutes and baseline PW was recorded. The participant then stood on the platform for 11 total minutes. PW images were captured once at the end of every minute for the first five minutes and a final PW measurement was captured after ten minutes of standing. A paired t-test was used to compare standing time points to baseline (α=0.05). RESULTS: After standing, time-averaged mean velocity (TAMean) significantly dropped through minutes one (pCONCLUSION: Blood flow through the anterior tibial artery is significantly altered with postural changes likely through cardiovascular responses. Vascular recovery is observed after three minutes while the average increase in vascular response occurs around ten minutes