Are Firearms Causing An Increase In Gun Crimes? A Granger Causality Test Of Dallas\u27 Street Gun Arsenal

From 1980 to 1992, Dallas, Texas saw an increase in both gun violence and the number of firearms. Nine firearm measures that define Dallas, Texas’ street gun arsenal along with two gun violence measures are used to test whether firearms are causing an increase in gun violence or gun violence is causing an increase in firearms. By estimating vector autoregressions and employing Granger causality tests on one firearm measure and one gun violence measure, the result is that the rising number of homicides committed with a gun are causing an increase in the total number of firearms. There is little evidence to suggest that firearms are causing the increases in gun violence

Reducing Cycle Time in Frozen Gel-Bag Production

PurFoods, estimates they will use two million gel-bags in the fiscal year to place in their meal packages. Currently the cycle time to freeze gel-bags in a -10℉ freezer is about 24 hours, causing issues with time needed for production

Highly-mass-loaded hot galactic winds are unstable to cool filament formation

When cool clouds are ram-pressure accelerated by a hot supersonic galactic wind, some of the clouds may be shredded by hydrodynamical instabilities and incorporated into the hot flow. Recent one-dimensional steady-state calculations show how cool cloud entrainment directly affects the bulk thermodynamics, kinematics, and observational characteristics of the hot gas. In particular, mass-loading decelerates the hot flow and changes its entropy. Here, we investigate the stability of planar and spherical mass-loaded hot supersonic flows using both perturbation analysis and three-dimensional time-dependent radiative hydrodynamical simulations. We show that mass-loading is stable over a broad range of parameters and that the 1D time-steady analytic solutions exactly reproduce the 3D time-dependent calculations, provided that the flow does not decelerate sufficiently to become subsonic. For higher values of the mass-loading, the flow develops a sonic point and becomes thermally unstable, rapidly cooling and forming elongated dense cometary filaments. We explore the mass-loading parameters required to reach a sonic point and the radiative formation of these filaments. For certain approximations, we can derive simple analytic criteria. In general a mass-loading rate similar to the initial mass outflow rate is required. In this sense, the destruction of small cool clouds by a hot flow may ultimately spontaneously generate fast cool filaments, as observed in starburst superwinds. Lastly, we find that the kinematics of filaments is sensitive to the slope of the mass-loading function. Filaments move faster than the surrounding wind if mass-loading is over long distances whereas filaments move slower than their surroundings if mass-loading is abrupt.Comment: 12 pages, 15 figures, submitted to MNRAS (21 July 2023

Temperature and Metallicity Gradients in the Hot Gas Outflows of M82

We utilize deep Chandra X-ray Observatory imaging and spectra of M82, the prototype of a starbursting galaxy with a multiphase wind, to map the hot plasma properties along the minor axis of the galaxy. We extract spectra from 11 regions up to 2.5 kpc from the starbursting midplane and model the data as a multi-temperature, optically thin thermal plasma with contributions from a non-thermal (power-law) component and from charge exchange (CX). We examine the gradients in best-fit parameters, including the intrinsic column density, plasma temperature, metal abundances, and number density of the hot gas as a function of distance from the M82 nucleus. We find that the temperatures and number densities of the warm-hot and hot plasma peak at the starbursting ridge and decreases along the minor axis. The temperature and density profiles are inconsistent with spherical adiabatic expansion of a super-heated wind and suggest mass loading and mixing of the hot phase with colder material. Non-thermal emission is detected in all of the regions considered, and CX comprises 8-25% of the total absorption-corrected, broad-band (0.5-7 keV) X-ray flux. We show that the abundances of O, Ne, Mg, and Fe are roughly constant across the regions considered, while Si and S peak within 500 pc of the central starburst. These findings support a direct connection between the M82 superwind and the warm-hot, metal-rich circumgalactic medium (CGM).Comment: 15 pages, 8 figures, ApJ in pres

Neural ODEs as a discovery tool to characterize the structure of the hot galactic wind of M82

Dynamic astrophysical phenomena are predominantly described by differential equations, yet our understanding of these systems is constrained by our incomplete grasp of non-linear physics and scarcity of comprehensive datasets. As such, advancing techniques in solving non-linear inverse problems becomes pivotal to addressing numerous outstanding questions in the field. In particular, modeling hot galactic winds is difficult because of unknown structure for various physical terms, and the lack of \textit{any} kinematic observational data. Additionally, the flow equations contain singularities that lead to numerical instability, making parameter sweeps non-trivial. We leverage differentiable programming, which enables neural networks to be embedded as individual terms within the governing coupled ordinary differential equations (ODEs), and show that this method can adeptly learn hidden physics. We robustly discern the structure of a mass-loading function which captures the physical effects of cloud destruction and entrainment into the hot superwind. Within a supervised learning framework, we formulate our loss function anchored on the astrophysical entropy ($K \propto P/\rho^{5/3}$). Our results demonstrate the efficacy of this approach, even in the absence of kinematic data $v$. We then apply these models to real Chandra X-Ray observations of starburst galaxy M82, providing the first systematic description of mass-loading within the superwind. This work further highlights neural ODEs as a useful discovery tool with mechanistic interpretability in non-linear inverse problems. We make our code public at this GitHub repository (https://github.com/dustindnguyen/2023_NeurIPS_NeuralODEs_M82).Comment: 9 Pages, 2 Figures, Accepted at the NeurIPS 2023 workshop on Machine Learning and the Physical Science

Drifting to oblivion? Rapid genetic differentiation in an endangered lizard following habitat fragmentation and drought

Aim The frequency and severity of habitat alterations and disturbance are predicted to increase in upcoming decades, and understanding how disturbance affects population integrity is paramount for adaptive management. Although rarely is population genetic sampling conducted at multiple time points, preand post-disturbance comparisons may provide one of the clearest methods to measure these impacts. We examined how genetic properties of the federally threatened Coachella Valley fringe-toed lizard (Uma inornata) responded to severe drought and habitat fragmentation across its range. Location Coachella Valley, California, USA. Methods We used 11 microsatellites to examine population genetic structure and diversity in 1996 and 2008, before and after a historic drought. We used Bayesian assignment methods and F-statistics to estimate genetic structure. We compared allelic richness across years to measure loss of genetic diversity and employed approximate Bayesian computing methods and heterozygote excess tests to explore the recent demographic history of populations. Finally, we compared effective population size across years and to abundance estimates to determine whether diversity remained low despite post-drought recovery. Results Genetic structure increased between sampling periods, likely as a result of population declines during the historic drought of the late 1990s–early 2000s, and habitat loss and fragmentation that precluded post-drought genetic rescue. Simulations supported recent demographic declines in 3 of 4 main preserves, and in one preserve, we detected significant loss of allelic richness. Effective population sizes were generally low across the range, with estimates ≤100 in most sites. Main conclusions Fragmentation and drought appear to have acted synergistically to induce genetic change over a short time frame. Progressive deterioration of connectivity, low Ne and measurable loss of genetic diversity suggest that conservation efforts have not maintained the genetic integrity of this species. Genetic sampling over time can help evaluate population trends to guide management

Reducing Cycle Time in Frozen Gel-Bag Production

PurFoods estimates they will use two million gel-bags this year in their packaged meal delivery boxes. Currently, cycle time to freeze gel-bags is about 24 hours. PurFoods would like to reduce this time by at least 25%, opening up valuable inventory space and providing flexibility in meeting market demands

X-ray Properties of NGC 253's Starburst-Driven Outflow

We analyze image and spectral data from $\approx$365~ks of observations from the {\it Chandra} X-ray Observatory of the nearby, edge-on starburst galaxy NGC~253 to constrain properties of the hot phase of the outflow. We focus our analysis on the $-$1.1 to $+$0.63 kpc region of the outflow and define several regions for spectral extraction where we determine best-fit temperatures and metal abundances. We find that the temperatures and electron densities peak in the central $\sim$250 pc region of the outflow and decrease with distance. These temperature and density profiles are in disagreement with an adiabatic spherically expanding starburst wind model and suggest the presence of additional physics such as mass loading and non-spherical outflow geometry. Our derived temperatures and densities yield few-Myr cooling times in the nuclear region, which may imply that the hot gas can undergo bulk radiative cooling as it escapes along the minor axis. Our metal abundances of O, Ne, Mg, Si, S, and Fe all peak in the central region and decrease with distance along the outflow, with the exception of Ne which maintains a flat distribution. The metal abundances indicate significant dilution outside of the starburst region. We also find estimates on the mass outflow rates which are $2.8\:M_{\odot}/\rm{yr}$ in the northern outflow and $3.2\:M_{\odot}/\rm{yr}$ in the southern outflow. Additionally, we detect emission from charge exchange and find it has a significant contribution ($20-42$\%) to the total broad-band ($0.5-7$~keV) X-ray emission in the central and southern regions of the outflow.Comment: 15 pages, 9 figure

African American community of southeast Rocky Mount, North Carolina : an action-oriented community diagnosis final report

During the fall of 2007 and spring of 2008, a team of five graduate students from the University of North Carolina at Chapel Hill’s School of Public Health conducted an Action-Oriented Community Diagnosis (AOCD) of the community in Southeast Rocky Mount. AOCD is a component of the curriculum for graduate students in the Department of Health Behavior and Health Education. Historically, the teaching team has been approached by community members seeking an assessment of their community. These community members then act as preceptors to student teams, introducing them to the community and aiding in our AOCD process. The process itself involves interacting with community members and service providers to systematically collect information about community strengths and challenges. The student team in Rocky Mount interviewed 19 service providers and 14 community members, conducted 2 focus groups and attended 12 community events. On April 12, the team hosted a community forum in Southeast Rocky Mount (SERM), at which findings were presented back to the community. Through break-out groups focused on discussing particular emerging themes, community members and service providers created action steps to address these themes. Hence, the AOCD process transformed from a diagnosis made by outsiders to a series of commitments by community participants to addressing their collective needs. At the beginning of the AOCD process, the student team conducted a secondary data review to learn more about Southeast Rocky Mount’s health, economics, crime and education status. The team then compared this data to that of the city of Rocky Mount, Edgecombe County and/or North Carolina depending upon the sources of data available. Rocky Mount is divided between two counties, Nash and Edgecombe, which at times affected the availability of data. The team also collected primary data through interviews and focus groups, which were guided by a predetermined set of questions. These discussions with community members and service providers provided much richer qualitative information. Team members transcribed and coded this data to determine which themes occurred most frequently. Identified strengths of the community included the people within the community and the history of a strong, thriving African American community in the area, among others. Meanwhile, challenges identified included: disparities between resources available in Nash County and Edgecombe County; lack of reliable public transportation; limited educational opportunities for youth and young adults; limited recreational and enrichment activities for youth; limited employment opportunities; dilapidated and sub-standard housing conditions; crime due to drugs and gang violence; and limited collaboration between community resources. Through consideration of these strengths and challenges, along with the coded interview data, the student team developed a list of emerging themes. These themes were presented to the eight community members and service providers that made up the forum planning committee. These members helped select the final themes to be used at the April forum. The initial list included: Youth, Education, Employment, Transportation, Crime, Housing/Cost of living, Parenting, and Communication between existing community resources. These eight preliminary themes were then narrowed down to the final five themes that we presented at the community form. The final themes selected for presentation to the community were: Youth, Employment, Connecting Community Resources, Crime, Housing. Approximately 65 individuals attended the community forum. Overall, participants were enthusiastic and optimistic when discussing the selected themes. At the end of the day, action steps were created for each theme and individuals personally committed to completing those steps. A future date was set for the community members and service providers to meet, without the student team, so that the AOCD process could continue within and among the community.Master of Public Healt

Mixed Chamber Ensembles

Kennesaw State University School of Music presents Mixed Chamber Ensembles, 2:00 p.m. performance.https://digitalcommons.kennesaw.edu/musicprograms/1396/thumbnail.jp