We have measured the flavor dependence of multiplicities for $\\pi^+$ and $\\pi^-$ production in semi-inclusive deep-inelastic scattering (SIDIS) on proton and deuteron targets. We used a 10.6 GeV electron beam at Jefferson Lab, and 4 msr solid angle spectrometers (HMS for electrons, SHMS for pions), the lepton vertex spanned the kinematic range $0.3 < x < 0.6$, $2 < Q^2 < 5$ GeV$^2$, and $4 < W^2 < 11$ GeV$^2$. The pion fractional momentum range was $0.3 < z < 0.7$ and the small transverse momentum range was $0 < P_t < .25$ GeV. We used the multiplicities to form sum-and-difference ratios, testing the validity of factorization. We extracted two favored and two unfavored $W$ dependent fragmentation functions (FFs) from these multiplicities. Assuming factorization at low $P_t$, we find that the two ``favored" FFs allow for isospin breaking (charge symmetry violation) at low $W$, while converging to a common value at the highest $W$ of this experiment. The two unfavored FFs are consistent with each other within the experimental uncertainties.

Master of Science / Department of Physics / Itzhak Ben-Itzhak / Imaging the interaction of molecular ion beams with ultrafast intense laser fields is a very powerful method to understand the fragmentation dynamics of molecules. Femtosecond laser pulses with different wavelengths and intensities are applied to dissociate and ionize molecular ions, and each resulting fragmentation channel can be studied separately by implementing a coincidence three-dimensional (3D) momentum imaging method. The work presented in this master’s report can be separated into two parts. First, the interaction between molecular ion beams and femtosecond laser pulses, in particular, the dissociation of CO[superscript]+ into C[superscript]++O, is studied. For that purpose, measurements are conducted at different laser intensities and wavelengths to investigate the possible pathways of dissociation into C[superscript]++O. The study reveals that CO[superscript]+ starts to dissociate from the quartet electronic state at low laser intensities. Higher laser intensity measurements, in which a larger number of photons can be absorbed by the molecule, show that the doublet electronic states with deeper potential wells, e.g. A [superscript]2Π, contribute to the dissociation of the molecule. In addition, the three-body fragmentation of CO[subscript]2[superscript]+ into C[superscript]++O[superscript]++O[superscript]+ is studied, and two breakup scenarios are separated using the angle between the sum and difference of the momentum vectors of two O[superscript]+ fragments. In the second part, improvements in experimental techniques are discussed. Development of a reflective telescope setup intended to increase the conversion efficiency of ultraviolet (UV) laser pulse generation is described, and the setup is used in the studies of CO[superscript]+ dissociation described in this report. The other technical study presented here is the measurement of the position dependence of timing signals picked off of a microchannel plate (MCP) surface. The experimental method is presented and significant time spread over the surface of the MCP detector is reported [1].

This dissertation focuses on the interdependency between causality, context and history in selected novels by E.L. Doctorow: The Book of Daniel (1971), Ragtime (1974), Loon Lake (1980), World's Fair (1985) and The Waterworks (1995). Doctorow' s fiction is marked by an apparent paradox: while it underscores fictionalization and sometimes distorts late nineteenth and twentieth century American history, it simultaneously purports to be a valid representation of the past. The novelist's implementation of causality which is a significant component of "the power of freedom", constitutes fiction's ability to convey truth without relying on factuality or "the power of the regime". According to Doctorow, the documented fact is already an interpretation which induces the perception that all documentation is subjective. The author composes fictional contexts that disregard the pretence of reliability in non-fictional texts. Doctorow focuses on how contexts are formed: the contexts are usually defined through the experience of characters who have been exposed to an event or events that were generated by motivations, for example, emotions of fear, racism, conviction, desire and greed, i.e., the catalysts that form history. Each of the novels discussed focuses on various aspects of society and the fate of specific individuals. The Book of Daniel proposes that a human being can only survive physically and spiritually by remaining a social entity. Ragtime focuses on the persistent illusion in history that society is fragmented. The various "faces" of society encountered by the main character in Loon Lake, mirror one another and reflect spiritual poverty. Consequently, Loon Lake demonstrates that the search for personal fulfilment does not require a physical journey, but an inner or spiritual exploration. World's Fair postulates that reality is never exclusively defined by either fortune or misfortune alone. The Waterworks offers perhaps one of the most significant evaluations of history as it perceives that the world in which we live is essentially unknown to us. We have neither the practical means to obtain a total perspective of what occurs in society (especially among politicians and the financially powerful) nor do we have sufficient skills to distinguish what the motivations of individuals' actions really entail. / Thesis (M.A.) Potchefstroom University for Christian Higher Education, 2000.

This dissertation focuses on the interdependency between causality, context and history in selected novels by E.L. Doctorow: The Book of Daniel (1971), Ragtime (1974), Loon Lake (1980), World's Fair (1985) and The Waterworks (1995). Doctorow' s fiction is marked by an apparent paradox: while it underscores fictionalization and sometimes distorts late nineteenth and twentieth century American history, it simultaneously purports to be a valid representation of the past. The novelist's implementation of causality which is a significant component of "the power of freedom", constitutes fiction's ability to convey truth without relying on factuality or "the power of the regime". According to Doctorow, the documented fact is already an interpretation which induces the perception that all documentation is subjective. The author composes fictional contexts that disregard the pretence of reliability in non-fictional texts. Doctorow focuses on how contexts are formed: the contexts are usually defined through the experience of characters who have been exposed to an event or events that were generated by motivations, for example, emotions of fear, racism, conviction, desire and greed, i.e., the catalysts that form history. Each of the novels discussed focuses on various aspects of society and the fate of specific individuals. The Book of Daniel proposes that a human being can only survive physically and spiritually by remaining a social entity. Ragtime focuses on the persistent illusion in history that society is fragmented. The various "faces" of society encountered by the main character in Loon Lake, mirror one another and reflect spiritual poverty. Consequently, Loon Lake demonstrates that the search for personal fulfilment does not require a physical journey, but an inner or spiritual exploration. World's Fair postulates that reality is never exclusively defined by either fortune or misfortune alone. The Waterworks offers perhaps one of the most significant evaluations of history as it perceives that the world in which we live is essentially unknown to us. We have neither the practical means to obtain a total perspective of what occurs in society (especially among politicians and the financially powerful) nor do we have sufficient skills to distinguish what the motivations of individuals' actions really entail. / Thesis (M.A.) Potchefstroom University for Christian Higher Education, 2000.

Global climate change and habitat fragmentation represent two of the greatest threats to biodiversity and ecological processes worldwide. It is predicted that anthropogenic induced climate change could represent a key factor for extinctions in the near future, considering that the Earth is set to become warmer than at any period in the past 40 million years. Habitat fragmentation and isolation pose a number of challenges for the fauna inhabiting degraded areas, including lack of dispersal opportunities leading to inbreeding resulting in a loss of genetic diversity, reduced reproductive fitness; increases in vulnerability to predation, hunting, and disease, and an inability to deal with or respond to environmental changes and/or disease. Madagascar, the fourth largest island in the world, is home to unprecedented levels of endemism, including over 100 species of lemur. The island has undergone a range of historical and contemporary landscape transformations, both natural and anthropogenic. These landscape transformations combined with additional human-induced disturbances, such as the illegal pet and bushmeat trades, have had devastating effects on the island’s extant primate populations. Thus, Madagascar’s lemurs have been deemed the most endangered group of mammals and now represent the highest primate conservation priority in the world. The ring-tailed lemur (Lemur catta) is endemic to the southern regions of the island and occupies an array of habitats. L. catta is known for its remarkable behavioral and ecological flexibility, which contributes to its ability to exist in a mostly fragmented landscape. While this species represents one of the most well studied Malagasy strepsirhines, there has been a paucity of research regarding the population and conservation genetics of this endangered species. The goal of my dissertation was to examine the influence of habitat fragmentation and isolation on the genetic diversity and population structuring of this flagship species in three populations living in the central highlands of Madagascar: Anja Reserve, Sakaviro, and Tsaranoro Valley. Non-invasive fecal samples from 30 individual lemurs were collected from three fragmented forests and genotyped at six polymorphic microsatellite loci. Population genetic analyses were examined via GenAlEx software and revealed a moderate level genetic diversity. Genetic differentiation (FST) among the three fragmented populations ranged from 0.05-0.11. These data suggest that the L. catta populations within south-central Madagascar have not yet lost significant genetic variation. To examine past and recent demographic declines or genetic bottlenecks, I employed three approaches, including mode-shift and M-Ratio tests, as well as a test to detect heterozygosity excess using three mutation models: the two-phase model (TPM), step-wise mutation model (SMM), and the infinite allele model (IAM). Results were equivocal depending on the test that was applied; however, a mode-shift was detected for Anja, signifying this population underwent a historical bottleneck. M-ratio tests revealed that all three populations suffered historical bottlenecks. A population bottleneck was indicated via heterozygosity excess under the IAM for both the Anja and Sakaviro populations. To understand the impact of natural (e.g., mountains) and anthropogenic disturbances (e.g., roads, habitat fragmentation) on male reproductive strategies (dispersal) and population structuring, I utilized both GenAlEx and STRUCTURE software. Population assignment analyses suffered from a likely ‘lack of signal’. Therefore, individuals were unable to be reliably assigned to their population of origin. Genetic population structure was ambiguous. These data suggest that that these three fragmented populations are not genetically differentiated enough for proper population assignment, or perhaps the sample is not robust enough for population assignment analyses to produce unequivocal results. My research represents the first population genetic data for ring-tailed lemurs within the central highlands, and thus, serves as a baseline for future investigations into the genetic health of these populations. These data support the suggestion that these three fragments represent areas in which concerted conservation efforts are necessary if genetic diversity is to be maintained and future demographic declines are to be prevented. My results are informative for the local community conservation associations working within south-central Madagascar and can now be applied to determine areas of conservation priority and where forest corridors will be the most beneficial for maintaining gene flow. The loss and fragmentation of habitat continues across Madagascar, including the central highlands; thus, all remaining L. catta populations should be considered a high conservation priority. If we are to safeguard the long-term viability of this species, continued conservation and research initiatives will be crucial. / Graduate / 0327 / 0369 / lemurgirl.clarke@gmail.com

The effects of Gated Communities (GCs) were analysed. According to the literature, these urban artefacts are negative for society. They are blamed to provoking social segregation, social exclusion and undermining democracy. In a Latin American context the consequences could be worse. Latin America has the highest level of social inequality in the world and the rapid growth of GCs is making this inequality more visible. This study implemented the concept of Social Capital, in order to understand the urban problems in this urban geography. The study is based in Machala, a mid-sized city in Ecuador. It was found that GCs’ residents lack of trust of outsiders, residents are more distant from disadvantage groups, social networks are being homogenised and there is a stigmatisation of life outside the community’s walls. This study seeks to create awareness on the type of urban growth in Machala by exploring the consequences of fragmentation, privatisation and segregation via GCs.

Sustainable Built Environments Senior Capstone Project / This study analyzes 15 years of wildlife tracking data across more than 40 transects in the Sky Islands surrounding landscape to investigate how human-wildlife encounters may respond to a decade of land development. The average detection of species per visit (ADPV), the quantification for human-wildlife encounters and indicator of species richness, was calculated for each transect across two sample periods 2001-2011 and 2011-2015. ArcMap was used to visualize the ADPV across sampling sites in the Sky Islands region. The p-value was then calculated to determine whether there was a significant difference between the ADPV of all species and of focal species before and after 2011. The results concluded there was no significant difference and the null hypothesis was accepted.

The dissertation details work aimed toward the development and implementation of a 3-D impact fragmentation module to perform rock fall analysis by taking into account impact fragmentation. This fragmentation module is based on a database of a large set of impact simulations using a fully calibrated discrete element model (DEM), and is employed to predict impact fragmentation processes in rockfall analysis by either training a neural network model or linearly interpolating the database. A DEM was employed to model impact fragmentation in the study. A DEM code was developed from scratch. The model was first calibrated and verified with experimental results to demonstrate the capability of modeling both quasi-static and dynamic material behavior. Algorithms to calibrate the model’s micro-parameters against triaxial tests on rocks were presented. Sensitivity analyses were used to identify the deformability micro-parameters by obtaining relationships between microscopic and macroscopic deformability properties. The strength model parameters were identified by a global optimization process aimed at minimizing the difference between computed and experimental failure envelopes. When applied to the experimental results of tested granite, this calibration process produced a good agreement between simulated and experimental results for both deformability and strength properties. Dynamic compression and SHPB tests were performed to verify the dynamic model. A strain-rate-dependent dynamic strength was observed in the experimental results. This strain-rate-dependent dynamic strength was also confirmed by the numerical results. No rate-dependent constitutive model was used in the DEM to simulate dynamic behavior. This simulated rate-dependent dynamic strength can be attributed to material inertia because the inertia inhibits crack growth. Some fundamental mechanisms of impact fragmentation associated with rockfalls were then numerically investigated. The developed DEM code was coupled with a simplified impact model inspired by the theory of dynamic foundations. It has been shown that the magnitude of impact velocity, the angle of the incidence, the ground condition all play very important roles in impact fragmentation. Several case studies were performed to validate the developed impact fragmentation module in rock fall analysis. It has been demonstrated that the developed fragmentation module can reasonably predict impact fragmentation and perform some risk analysis in rock fall analysis. / text

Recent changes in the media environment have generated serious debates about whether these changes will foster or hamper the proper functioning of democracy. Along this line, the tendency toward audience fragmentation has arisen as one of the main concerns that might undermine a healthy democracy. People are not likely to discuss common social problems and understand each other in fragmented society, much less agree on methods to solve them. This dissertation investigates whether the environmental changes result in the audience fragmentation. This study first clarifies conceptual and operational definition of fragmentation. It is conceptualized as division of the general public into small groups not communicating with each other, and operationalized as existence of a common agenda by means of incidental news exposure facilitated by structural factors of online communication, an exemplar of the new information environment. Data from several different methods are employed to investigate effects of new media on fragmentation: a content analysis, a survey, and a laboratory experiment. The results provide evidence supporting that the public still can share experiences by learning a common agenda from the media on the Internet, the medium considered an icon of the new media environment. Findings of the content analysis found significant positive correlations between news agenda of different media outlets, indicating that there is a common agenda in the media. Environmental factors of the media environment rather than individual differences in political predispositions have strong influence on people’s incidental news exposure, a key route to acquire a common agenda. A series of analyses based on the survey found that overall frequency of Internet use significantly predicted individuals’ reports of incidental news exposure online, whereas there was no significant relationship between political predispositions and incidental exposure. It also appears that certain online activities such as getting entertainment/sports information significantly predicted the incidental news exposure. The incidental news exposure was found to have actual effects on people’s learning of a common agenda and recognition/recall of information carried by stimulus messages in the experiment. The implications of the findings are discussed in terms of communication research and media/democracy. / text

Habitat loss, habitat fragmentation and species invasions have been recognized as three of the leading threats to biodiversity. I examined the effects of habitat loss and fragmentation on native and invasive plants in central Texas. During the last century, the density and abundance of woody plants has been increasing in the savannas of eastern Edwards Plateau. This process, known as woody plant encroachment, not only reduces the amount of open herbaceous habitat but also fragments that habitat creating smaller and more isolated patches. In three studies, I investigated the consequences of this habitat loss and fragmentation for plants which do not occur under the cover of woody plants including native grasses and forbs and the invasive Eurasian bunchgrass, Bothriochloa ischaemum (King Ranch Bluestem). In the first study, I show that woody plant encroachment reduces native herbaceous species richness (the number of species in a given area). Using a collection of historical aerial photographs, I demonstrate that current native herbaceous species richness was most strongly related to recent habitat amount, but to the degree of habitat fragmentation at least 50 years ago. In a second study, I show that the presence of B. ischaemum was negatively related to the degree of fragmentation in the surrounding landscape. Finally, I found that B. ischaemum had higher rates of germination and growth in experimental plots where the species commonly lost with woody plant encroachment were removed than in unmanipulated control plots. Together, this work suggests that woody plant encroachment is directly slowing the spread of an invasive species while indirectly facilitating its establishment. / text