Twentieth Century March

https://digitalcommons.library.umaine.edu/mmb-ps/2686/thumbnail.jp

International March

https://digitalcommons.library.umaine.edu/mmb-ps/2499/thumbnail.jp

White Dwarf Cosmochronology in the Solar Neighborhood

The study of the stellar formation history in the solar neighborhood is a powerful technique to recover information about the early stages and evolution of the Milky Way. We present a new method which consists of directly probing the formation history from the nearby stellar remnants. We rely on the volume complete sample of white dwarfs within 20 pc, where accurate cooling ages and masses have been determined. The well characterized initial-final mass relation is employed in order to recover the initial masses (1 < M/Msun < 8) and total ages for the local degenerate sample. We correct for moderate biases that are necessary to transform our results to a global stellar formation rate, which can be compared to similar studies based on the properties of main-sequence stars in the solar neighborhood. Our method provides precise formation rates for all ages except in very recent times, and the results suggest an enhanced formation rate for the solar neighborhood in the last 5 Gyr compared to the range 5 < Age (Gyr) < 10. Furthermore, the observed total age of ~10 Gyr for the oldest white dwarfs in the local sample is consistent with the early seminal studies that have determined the age of the Galactic disk from stellar remnants. The main shortcoming of our study is the small size of the local white dwarf sample. However, the presented technique can be applied to larger samples in the future.Comment: 25 pages, 10 figures, accepted for publication in the Astrophysical Journa

An Analysis of Heterogeneity in Futuristic Unmanned Vehicle Systems

Recent studies have shown that with appropriate operator decision support and with enough automation aboard unmanned vehicles, inverting the multiple operators to single-vehicle control paradigm is possible. These studies, however, have generally focused on homogeneous teams of vehicles, and have not completely addressed either the manifestation of heterogeneity in vehicle teams, or the effects of heterogeneity on operator capacity. An important implication of heterogeneity in unmanned vehicle teams is an increase in the diversity of possible team configurations available for each operator, as well as an increase in the diversity of possible attention allocation schemes that can be utilized by operators. To this end, this paper introduces a resource allocation framework that defines the strategies and processes that lead to alternate team configurations. The framework also highlights the sub-components of operator attention allocation schemes that can impact overall performance when supervising heterogeneous unmanned vehicle teams. A subsequent discrete event simulation model of a single operator supervising multiple heterogeneous vehicles and tasks explores operator performance under different heterogeneous team compositions and varying attention allocation strategies. Results from the discrete event simulation model show that the change in performance when switching from a homogeneous team to a heterogeneous one is highly dependent on the change in operator utilization. Heterogeneous teams that result in lower operator utilization can lead to improved performance under certain operator strategies.Prepared for Charles River Analytic

Audio Decision Support for Supervisory Control of Unmanned Vehicles : Literature Review

Purpose of this literature review: To survey scholarly articles, books and other sources (dissertations, conference proceedings) relevant to the use of the audio supervisory control of unmanned vehicles.Prepared for Charles River Analytic

Elemental and isotopic fractionation in 3He-rich solar energetic particle events

Using data from the Solar Isotope Spectrometer (SIS) on the Advanced Composition Explorer (ACE) mission, heavy ion composition measurements have been made in 26^3He-rich solar energetic particle (SEP) events that occurred between 1998 and 2004. Relative abundances of 13 elements from C through Ni have been investigated, as have the isotopic compositions of the elements Ne and Mg. We find a general tendency for the abundances to follow trends similar to those found in gradual SEP events, in which fractionation can be represented in the form of a power-law in Q/M. However several deviations from this pattern are noted that may provide useful diagnostics of the acceleration process occurring in solar flares

Heavy-ion Fractionation in the Impulsive Solar Energetic Particle Event of 2002 August 20: Elements, Isotopes, and Inferred Charge States

Measurements of heavy-ion elemental and isotopic composition in the energy range ~12-60 MeV nucleon^(–1) are reported from the Advanced Composition Explorer/Solar Isotope Spectrometer (ACE/SIS) instrument for the solar energetic particle (SEP) event of 2002 August 20. We investigate fractionation in this particularly intense impulsive event by examining the enhancements of elemental and isotopic abundance ratios relative to corresponding values in the solar wind. The elemental enhancement pattern is similar to those in other impulsive events detected by ACE/SIS and in compilations of average impulsive-event composition. For individual elements, the abundance of a heavy isotope (mass M_2) is enhanced relative to that of a lighter isotope (M_1) by a factor ~(M_(1)/M_2)^α with α ≃ 15. Previous studies have reported elemental abundance enhancements organized as a power law in Q/M, the ratio of estimated ionic charge to mass in the material being fractionated. We consider the possibility that a fractionation law of this form could be responsible for the isotopic fractionation as a power law in the mass ratio and then explore the implications it would have for the ionic charge states in the source material. Assuming that carbon is fully stripped (Q_C = 6), we infer mean values of the ionic charge during the fractionation process, Q_Z , for a variety of elements with atomic numbers 7 ≤ Z ≤ 28. We find that Q_(Fe) ≃ 21-22, comparable to the highest observed values that have been reported at lower energies in impulsive SEP events from direct measurements near 1 AU. The inferred charge states as a function of Z are characterized by several step increases in the number of attached electrons, Z – Q_Z . We discuss how this step structure, together with the known masses of the elements, might account for a variety of features in the observed pattern of elemental abundance enhancements. We also briefly consider alternative fractionation laws and the relationship between the charge states we infer in the source material and those derived from in situ observations

Understanding sexual violence and factors related to police outcomes

In the year ending March 2020, an estimated 773,000 people in England and Wales were sexually assaulted. These types of crimes have lasting effects on victims’ mental health, including depression, anxiety, and post-traumatic stress disorder. There is a large body of literature which identifies several factors associated with the likelihood of the victim reporting a sexual assault to the police, and these differences may be due to rape myth stereotypes which perpetuate the belief that rape is only “real” under certain conditions. Less is known, however, about the effect these rape myths and stereotypes have on the investigation process itself and the subsequent police outcomes assigned to sex offences. This study aimed to address this gap, providing a profile of all RASSO (rape and serious sexual offences) committed over a 3-year period in one English police force, the police outcomes of these offences, and whether any offences, suspect, or victim variables were associated with different outcomes, in particular the decision to charge or cases where victims decline to prosecute. In line with previous research, the majority of victims were female while the majority of suspects were male, and the most frequent victim–suspect relationship was acquaintance, followed by partner/ex-partner. Charge outcomes were more likely in SSOs and less in rape offences, more likely with stranger offences and less likely than offences committed by partners/ex-partners and relatives, and some non-white suspects were more likely to be charged than suspects of other ethnicities, including white suspects. Victim attrition was more likely in cases where the suspect was a partner or ex-partner and least likely where the suspect was a stranger, more likely in SSOs than in rape cases, and more likely when the victim ethnicity was “other”. Law enforcement should be aware of the potential biases, both relating to rape myths and stereotypes and to the biased treatment of victims and suspects based on demographic characteristics, and work to eliminate these to ensure a fairer and more effective RASSO investigative process

Information Requirements for MCM and ISR Missions : PUMA Phase II

This document contains display requirements for Littoral Combat Ship (LCS) control station displays to be used by unmanned vehicle units in support of heterogeneous unmanned vehicle missions (such as Special Operations Force (SOF) insertion). The method used for generating the requirements was that of a Hybrid Cognitive Task Analysis (CTA)1 which entails describing a scenario overview of a representative mission, generating event flow diagrams, and depicting decision ladders for the key decisions identified in the event flow diagrams. These steps are then used together to generate an informational requirements summary which includes the situational awareness requirements that are derived from the event flow and display requirements of the decision ladders. This method was developed in Phase I of the PUMA (Plan Understanding for Mixed-initiative control of Autonomous systems) project2. In PUMA I, the mission scenario primarily consisted of Intelligence, Surveillance and Reconnaissance (ISR) tasks. For PUMA II, the scenario has been expanded to include Mine Counter Measures (MCM), Harbor Bottom Image-Mapping (HBI), and Anti- Terrorism / Force Protection (AT/FP) mission types. There is a specific emphasis on the MCM and ISR missions to highlight the informational requirement differences between the two task types. This document incorporates the expanded vehicle and mission type heterogeneities that are present in PUMA II in order to develop a cohesive set of informational requirements necessary for such a complex mission.Prepared for Charles River Analytic