Shape predicates allow unbounded verification of linearizability using canonical abstraction

Canonical abstraction is a static analysis technique that represents states as 3-valued logical structures, and is able to construct finite representations of systems with infinite statespaces for verification. The granularity of the abstraction can be altered by the definition of instrumentation predicates, which derive their meaning from other predicates. We introduce shape predicates for preserving certain structures of the state during abstraction. We show that shape predicates allow linearizability to be verified for concurrent data structures using canonical abstraction alone, and use the approach to verify a stack and two queue algorithms. This contrasts with previous efforts to verify linearizability with canonical abstraction, which have had to employ other techniques as well

The origin of amorphous rims on lunar plagioclase grains: Solar wind damage or vapor condensates

A distinctive feature of micron sized plagioclase grains from mature lunar soils is a thin (20 to 100 nm) amorphous rim surrounding the grains. These rims were originally described from high voltage electron microscope observations of lunar plagioclase grains by Dran et al., who observed rims up to 100 nm thick on plagioclase grains from Apollo 11 and 12 soils. These rims are believed to be the product of solar wind damage. The amorphous rims were studied on micron sized plagioclase grains from a mature Apollo 16 soil using a JEOL 200FX transmission electron microscope equipped with an energy dispersive x ray spectrometer. It was found that the amorphous rims are compositionally distinct from the interior plagioclase and it is proposed that a major component of vapor condensates is present in the rims

An Assessment of Mental Health Services for Veterans in the State of Texas

This report describes the complex challenges faced by veterans and their families in seeking, navigating, and attaining adequate mental health care in Texas. There are 1.7 million veterans in Texas, comprising 8.6 percent of the adult population. According to the U.S. Department of Veteran Affairs (VA), the number of veterans requiring mental health services has grown dramatically and will continue to increase, making veterans’ mental health care an urgent issue in Texas. The federal agencies responsible for military and veterans mental health care, the U.S. Department of Defense (DoD) and the VA, have created new programs and invested significant financial and staff resources. Despite barriers to addressing veterans mental health needs. Texas state agencies have increased funding and instituted new mental health programs supporting returning veterans. Nonprofit agencies focused on veteran’s mental health have multiplied across Texas and the U.S. over the past decade to fill gaps in care. While these organizations provide a growing and increasingly diverse set of resources for veterans to extend the scope of support, volunteer efforts can suffer from fragmentation and overlap. The report identifies current practices, challenges, and opportunities within and across each group of service providers. The report draws on government reports, scholarly literature, and agency websites, as well as interviews with counselors, Veteran Service Officers, nonprofit providers, state officials, and veterans themselves. This report offers five recommendations toward the goal that veterans’ mental health care in Texas become comprehensive, inclusive, effective, and efficient. First, there is a need for greater inter-agency communication across organizations, improved outreach efforts, and increased services for hard-to-reach populations, such as homeless veterans. Second, federal agencies ought to address staff shortages, improve the transition from DoD to VA care, and increase feedback. Third, at the state level, specialized services are needed to address unique veterans’ needs concentrated in cities across Texas as well as those dispersed in rural areas. Fourth, providers can improve mental health care by integrating social services and law enforcement. Fifth, both veterans and providers can benefit if they recognize opportunities for cooperation and coordination and work towards long-term goals that emphasize outcomes that improve the lives of returning veterans. This research was funded in part by the Jack S. Blanton Research Fellowship and the George A. Roberts Research Fellowship of the IC² Institute.IC2 Institut

Momentum, Heat, and Neutral Mass Transport in Convective Atmospheric Pressure Plasma-Liquid Systems and Implications for Aqueous Targets

There is a growing interest in the study of plasma-liquid interactions with application to biomedicine, chemical disinfection, agriculture, and other fields. This work models the momentum, heat, and neutral species mass transfer between gas and aqueous phases in the context of a streamer discharge; the qualitative conclusions are generally applicable to plasma-liquid systems. The problem domain is discretized using the finite element method. The most interesting and relevant model result for application purposes is the steep gradients in reactive species at the interface. At the center of where the reactive gas stream impinges on the water surface, the aqueous concentrations of OH and ONOOH decrease by roughly 9 and 4 orders of magnitude respectively within 50 $\mu$m of the interface. Recognizing the limited penetration of reactive plasma species into the aqueous phase is critical to discussions about the therapeutic mechanisms for direct plasma treatment of biological solutions. Other interesting results from this study include the presence of a 10 K temperature drop in the gas boundary layer adjacent to the interface that arises from convective cooling and water evaporation. Accounting for the resulting difference between gas and liquid bulk temperatures has a significant impact on reaction kinetics; factor of two changes in terminal aqueous species concentrations like H$_2$O$_2$, NO$_2^-$, and NO$_3^-$ are observed if the effect of evaporative cooling is not included

Fully Coupled Simulation of the Plasma Liquid Interface and Interfacial Coefficient Effects

There is a growing interest in the study of coupled plasma-liquid systems because of their applications to biomedicine, biological and chemical disinfection, agriculture, and other areas. Without an understanding of the near-surface gas dynamics, modellers are left to make assumptions about the interfacial conditions. For instance it is commonly assumed that the surface loss or sticking coefficient of gas-phase electrons at the interface is equal to 1. In this work we explore the consequences of this assumption and introduce a couple of ways to think about the electron interfacial condition. In one set of simulations we impose a kinetic condition with varying surface loss coefficient on the gas phase interfacial electrons. In a second set of simulations we introduce a Henry's law like condition at the interface in which the gas-phase electron concentration is assumed to be in thermodynamic equilibrium with the liquid-phase electron concentration. It is shown that for a range of electron Henry coefficients spanning a range of known hydrophilic specie Henry coefficients, the gas phase electron density in the anode can vary by orders of magnitude. Varying reflection of electrons by the interface also has consequences for the electron energy profile. This variation in anode electron density and energy as a function of the interface characteristics could also lead to significant variation in near-surface gas chemistries when such reactions are included in the model; this could very well in turn affect the reactive species impinging on the liquid surface. We draw the conclusion that in order to make more confident model predictions about plasma-liquid systems, finer scale simulations and/or new experimental techniques must be used to elucidate the near-surface gas phase electron dynamics

Impact glasses from the less than 20-micrometer fraction of Apollo 17 soils 72501 and 78221

The chemical compositions of microscopic glasses produced during meteoroid impacts on the lunar surface provide information regarding the various fractionation processes that accompany these events. To learn more about these fractionation processes, we studied the compositions of submicrometer glass spheres from two Apollo 17 sampling sites using electron microscopy. The majority of the analyzed glasses show evidence for varying degrees of impact-induced chemical fractionation. Among these are HASP glasses (high-Al, Si-poor), which are believed to represent the refractory residuum left after the loss of volatile elements (e.g., Si, Fe, Na) from the precursor material. In addition to HASP-type glasses, we also observed a group of volatile-rich, Al-poor (VRAP) glasses that represent condensates of vaporized volatile constituents, and are complementary to the HASP compositions. High-Ti glasses were also found during the course of this study, and are documented here for the first time