5,179 research outputs found

    Organizational Fragmentation and the Trajectory of Militant Splinter Groups

    Get PDF
    Militant organizations commonly break down and split apart, with new groups emerging from the ranks of existing organizations. From Syria to Iraq to Afghanistan, militant groups have splintered and proliferated in this way, creating fragmented oppositions that significantly complicate the conflict landscape. This process of organizational splintering historically has created some of the deadliest and most well known organizations including Al Shabaab, Black September, and the Real IRA. However, at other times the new organizations have quickly disappeared, failing to impact the conflict in any meaningful way.What explains this variation in the trajectory of militant splinter groups over time? Specifically, this dissertation explores why some organizational fractures produce new groups that are durable and increasingly radicalized, while others merely fall apart. This is an important topic that has ramifications for how academics and policymakers alike understand the behavior of specific actors and also the evolution of fragmented conflicts around the globe. I develop a new theory to explain variation in rates of survival and radicalization that focuses on the content and the consistency of internal organizational preferences. I argue that the content of group preferences can explain relative rates of radicalization and tactical change whereas the consistency or alignment of those preferences influences their chances of survival. Splinter groups that attract tactical and strategic hardliners are most likely to radicalize while inconsistent internal preferences lead to feuding, a lack of cohesion, and a lower likelihood of survival. Although impossible to directly observe, I show that different pathways of organizational breakdown, which one can observe, strongly shape the distribution of group preferences. In other words, different pathways of group formation have enduring effects on organizational behavior. I test my theory with a mixed-methods research design. The empirical results from analyzing a new data set provide robust cross-national support for my theory while my case study of republican militants in Northern Ireland - supplemented by three months of field world in Belfast, London, and Dublin - demonstrates the theory\u27s causal mechanisms in action. These findings confirm that the conditions leading to group formation play an enduring role, driving group behavior well into the future

    Longitudinal dispersion in nonuniform isotropic porous media

    Get PDF
    A theoretical and experimental investigation has been made of the longitudinal dispersion of chemically and dynamically passive solutes during flow through nonuniform, isotropic porous media. Both theoretical and experimental results are limited to the high Peclet number, low Reynolds number flow regime. The goal of the theoretical investigation is to provide a quantitative method for calculating the coefficient of longitudinal dispersion using only measurable structural features of the porous medium and the characteristics of the carrying fluid and solute. A nonuniform porous medium contains variations in grain scale pore structure, but is homogeneous at the macroscopic level for quantities such as the permeability or porosity. A random capillary tube network model of nonuniform porous media is developed which uses a pore radius distribution and pore length distribution to characterize the grain scale structure of porous media. The analysis gives the asymptotic longitudinal dispersion coefficient in terms of integrals of kinematic properties of solute particles flowing through individual, random capillary tubes. However, shear dispersion within individual capillary tubes is found to have negligible impact on the overall longitudinal dispersion in porous media. The dispersion integrals are evaluated using a Monte Carlo integration technique. An analysis of the permeability in nonuniform porous media is used to establish a proper flow field for the analysis of longitudinal dispersion. The experimental investigation of longitudinal dispersion is carried out by measuring (with conductivity probes) the development of an initially sharp miscible displacement interface. The experimentally determined longitudinal dispersion coefficients are found to be greater in nonuniform media than in uniform media when compared using Peclet numbers based on the geometric mean grain diameter. The experimental breakthrough curves also display highly asymmetrical shapes, in which the "tail" of the breakthrough is longer than would be expected from advection-diffusion theory. Although the theoretical model does not predict the tailing behavior, it is found that the leading portion of the breakthrough curve is described by advection-diffusion theory. The theoretically determined longitudinal dispersion coefficients lie roughly within a factor of 1.35 of the measured values. The material presented in this report is essentially the same as the thesis submitted by the author in partial fulfillment of the requirements for the degree of Doctor of Philosophy

    Investigating the Role of Geospatial Technologies as a Supplement to Environmental Education: Development of an Environmental Data Collection Application and Its Implementation in the Classroom

    Get PDF
    Informal STEM (Science, Technology, Engineering, and Math) education refers to science learning that takes place in a non-traditional setting, such as a museum, a library, and outside a classroom, based on the methods different from the traditional pen-to-paper style of classroom learning. A critical component of Informal STEM education is to ensure student understanding and using available technologies to better analyze and convey scientific data, particularly for the data that are spatial in nature. Combining mobile technologies with geographic information systems (GIS) in field data collection provides unique opportunities for students to feel stimulated and engaged in what they are learning and to take ownership of their own learning process.In this thesis, I developed a publicly available and open access data collection application and investigated its impacts on students’ engagement and perception of the incorporation of technology in their learning within the environmental science curricula. The analyses of pre- and post-surveys indicate that the inclusion of geospatial technologies as a part of curricula can significantly boost students’ engagement by allowing the opportunities to 1) take the lead on their own research, 2) view field data in real-time as opposed to looking at a database in hindsight, and 3) view and analyze multiscale data as it is presented during field analysis. The findings of this study are consistent with previous studies, suggesting a strong correlation between the inclusion of geospatial technologies as a part of curricula and student engagement and performance

    PREFERENTIAL PATHWAYS FOR VAPOR INTRUSION: SITE SCREENING AND FIELD SAMPLING OF SEWERS TO ASSESS INHALATION EXPOSURE RISKS

    Get PDF
    Hazardous waste sites and aging wastewater infrastructure are common in the United States. There are hundreds of thousands of contaminated sites and more than a million miles of sewer pipes. Populations living close to hazardous waste sites often suffer from increased risk of adverse health effects due to exposure to contaminated environmental media. Vapor intrusion is one process by which nearby populations can be exposed to volatile organic compounds (VOCs). Aging wastewater infrastructure is important for vapor intrusion site assessments because sewer pipes can serve as preferential vapor transport pathways. Near contaminated sites, pipe deterioration allows migration of contaminants into sewers and potential accumulation of chemical vapors in sewer gas and nearby buildings. The objectives of this study are to develop a screening-level method to identify contaminated sites where additional evaluation of vapor intrusion is necessary, and then conduct field sampling at these sites to investigate sewers as potential vapor intrusion pathways. Sampling was conducted at four study sites, which consist of former and current dry cleaning facilities located in Lexington, Kentucky. The results of this study demonstrate that preferential vapor intrusion pathways such as sewers can facilitate the spread of vapor intrusion exposure risks beyond source areas of contamination

    GPU implementation of video analytics algorithms for aerial imaging

    Get PDF
    This work examines several algorithms that together make up parts of an image processing pipeline called Video Mosaicing and Summarization (VMZ). This pipeline takes as input geospatial or biomedical videos and produces large stitched-together frames (mosaics) of the video's subject. The content of these videos presents numerous challenges, such as poor lighting and a rapidly changing scene. The algorithms of VMZ were chosen carefully to address these challenges. With the output of VMZ, numerous tasks can be done. Stabilized imagery allows for easier object tracking, and the mosaics allow a quick understanding of the scene. These use-cases with aerial imagery are even more valuable when considered from the edge, where they can be applied as a drone is collecting the data. When executing video analytics algorithms, one of the most important metrics for real-life use is performance. All the accuracy in the world does not guarantee usefulness if the algorithms cannot provide that accuracy in a timely and actionable manner. Thus the goal of this work is to explore means and tools to implement video analytics algorithms, particularly the ones that make up the VMZ pipeline, on GPU devices{making them faster and more available for real-time use. This work presents four algorithms that have been converted to make use of the GPU in the GStreamer environment on NVIDIA GPUs. With GStreamer these algorithms are easily modular and lend themselves well to experimentation and real-life use even in pipelines beyond VMZ.Includes bibliographical references

    Too Big to Fail in the Local Group

    Get PDF
    We compare the dynamical masses of dwarf galaxies in the Local Group (LG) to the predicted masses of halos in the ELVIS suite of Λ\LambdaCDM simulations, a sample of 48 Galaxy-size hosts, 24 of which are in paired configuration similar to the LG. We enumerate unaccounted-for dense halos (Vmax≳25V_\mathrm{max} \gtrsim 25 km s−1^{-1}) in these volumes that at some point in their histories were massive enough to have formed stars in the presence of an ionizing background (Vpeak>30V_\mathrm{peak} > 30 km s−1^{-1}). Within 300 kpc of the Milky Way, the number of unaccounted-for massive halos ranges from 2 - 25 over our full sample. Moreover, this "too big to fail" count grows as we extend our comparison to the outer regions of the Local Group: within 1.2 Mpc of either giant we find that there are 12-40 unaccounted-for massive halos. This count excludes volumes within 300 kpc of both the MW and M31, and thus should be largely unaffected by any baryonically-induced environmental processes. According to abundance matching -- specifically abundance matching that reproduces the Local Group stellar mass function -- all of these missing massive systems should have been quite bright, with M⋆>106M⊙M_\star > 10^6M_\odot. Finally, we use the predicted density structure of outer LG dark matter halos together with observed dwarf galaxy masses to derive an M⋆−VmaxM_\star-V_\mathrm{max} relation for LG galaxies that are outside the virial regions of either giant. We find that there is no obvious trend in the relation over three orders of magnitude in stellar mass (a "common mass" relation), from M⋆∼108−105M⊙M_\star \sim 10^8 - 10^5 M_\odot, in drastic conflict with the tight relation expected for halos that are unaffected by reionization. Solutions to the too big to fail problem that rely on ram pressure stripping, tidal effects, or statistical flukes appear less likely in the face of these results.Comment: 16 pages, 14 figures, 2 tables, submitted to MNRA

    Transcript for Episode 08: Big Battle - Serious Stakes: The Big 1967-71 Sales Tax Fight

    Get PDF
    https://digitalcommons.mtech.edu/crucible_transcriptions/1007/thumbnail.jp
    • …
    corecore