Thesis (M.S.)--Rochester Institute of Technology, 1994. / Typescript. Includes bibliographical references (leaf 67).

The first stars, galaxies and black holes in the universe produced large quantities of ionising UV radiation; forming H II regions in the neutral gas before the Epoch of Reionisation (EoR). These ionisation fronts will have come into contact with overdensities in the surrounding Intergalactic Medium (IGM), including haloes which were in the process of collapse. Previous studies have shown that the feedback processes on these secondary haloes can either disrupt the gas, or induce further cooling from the formation of molecular hydrogen. The ionising source will eventually die and create a defunct H II region, which expands into the surrounding neutral IGM. Minihaloes at the edge of these defunct H II regions are particularly susceptible to positive feedback due to not having been photoevaporated like their counterparts further inside the ionised volume. In this thesis, numerical simulations of minihaloes at the edges of H II regions formed by the first luminous objects before the EoR are presented. A methodology of including secondary ionisations from high energy photons is also implemented into the radiation hydrodynamical code ZEUS-RT. The interaction of differing spectral index sources with minihaloes including secondary ionisation is discussed. The secondary ionisations show the greatest effect for hard spectral sources with a large fraction of high energy photons; where a decrease in photoheating and an increase in ionisation rate is found at the outer reaches of the ionisation front (I-front). The increased ionisation rate lowers the optical depth of the gas for subsequent photons, and thus reduces the trapping of I-fronts in high densities found in the minihalo cores. The ratio of the free electron fraction to the temperature in the core of the minihaloes is found to constrain the resulting evolution. A high ratio is correlated with the creation of molecular hydrogen, which can then induce further cooling and the collapse of the system.A large parameter suite of 3780 two-dimensional minihalo models utilising radiative hydrodynamical simulations with 12 species and a coupled reaction network, including H2 cooling, HD cooling, Lyman-Werner radiation and secondary ionisation is performed. The parameter space includes: the spectral index representing different sources such as quasars or galaxies, the mass of the minihaloes from 105 - 106 Mʘ, the redshift of ionisation from z ~ 10 - 30, and other factors which denote the position of the minihalo relative to the boundary of the H II region. Minihaloes with average core densities of n0 = 2 - 10 cm-3 show almost unanimous positive feedback, while the majority of minihaloes under this average density are disrupted. Minihaloes with core densities above this value generally would have collapsed in isolation anyway, but are found to not be delayed by the I-front. The H2 fraction in the minihalo gas is also increased in models with no blowout by factors between 2 - 100 times that of an isolated minihalo. This is especially significant for lower redshift, z ≤ 15, minihaloes. Finally, a parameter suite of larger 106 - 107 Mʘ minihaloes results in the creation of self-gravitating clumps of gas moving out of the dark matter potential. The gas core is compressed by the I-front, enriched with molecular hydrogen, and ejected by the pressure front after the source dies. These "baryon bullets" could be progenitors of primordial globular clusters found in the haloes of galaxies today. Properties such as old stellar populations and the lack of dark matter haloes can be explained by this radiative ejection method. The dynamical nature of these interacting systems and diversity of subsequent evolution suggest that minihaloes less than 108 Mʘ are important in the early formation history of the universe, and in determining the constraining parameters of the EoR. The feedback mechanisms investigated, and secondary ionisation physics, should be included in astrophysical simulations and analytical calculations determining the evolution of the universe at this critical epoch.

The history of forensic firearms examination was evaluated to determine how the field has developed during the past 200 years; especially within the past 100 years. As aresult of this evaluation, some related issues were identified for study. The economic and general uses of firearms reference collections were considered as the collections represent potential security considerations within forensic laboratories. A survey was conducted to determine how firearms examiners used their collections, as well as their receptivity to augmenting the collections with modem technology such as photographs and CD-ROM's. A world-wide survey resulted in responses from 110 forensic laboratories. Examiners stated that the collections were used for training, repairing damaged evidence firearms, and demonstration purposes, and whilst they were prepared to accept modem techriology to augment their collection, stated that such augmentation could not replace the actual collection. Research was conducted to partially answer some legal issues, such as Daubert, et al., by test firing bullets from consecutively rifled barrels to obtain best known 'match' and 'non-match' bullets. To date, some 201 examiners from several countries have evaluated the bullet test sets with no errors. Further research was conducted by test firing four cartridges from 617 similar 9mm Glock pistols and microscopically evaluating the fired cartridge casings to determine if they were identifiable to themselves and not the other casings. All of the casings were identifiable to themselves and not to the other 616 casings. Advances in technology have allowed the development of automated ballistics imaging systems. Research, using the previously cited test bullets and cartridge casings, was conducted to evaluate the capability of the various systems, in conjunction with the abilities offirearms examiners. Three different automated systems were used to evaluate the bullets from the l0-barrel test results. One automated system was used to evaluate the 617 cartridge casings, again with excellent results.

This thesis is an examination of a firearm identification system that creates a three-dimensional image of a bullet in order to record the depth and length of striations occurring along the bullet's surface. Ballistics evidence is an area of forensics in great need of further development. The advent of more sophisticated firearms such as semi-automatic and automatic weapons has increased the need for a matching system that connects bullets found at crime scenes with suspect guns. In the past, control bullets matching ones found at the crime scene have been test fired and then examined by a comparison microscope for similarities with the evidence bullet. The purpose of this thesis is to examine data collected by an emerging system that uses three-dimensional technology by way of a laser and convex mirrors to create a digitized representation of the lands and grooves of a bullet. This representation is a measure of the depth of striations or markings created on the bullet's surface during the firing event. The objective of this thesis is to statistically examine the data collected by this system, which consists of bullets produced by eight different manufacturers. The data for this thesis comes from a pilot study conducted by the creators of a three-dimensional system called SCICLOPS. Variables examined include the maximum and minimum number of striations recorded, the relative position of the bullet (as determined by the six lands and grooves measured by the system), and the manufacturer type. It is hypothesized that there will be differences in the number of striations measured across manufacturer types. Results indicate that manufacturer type may play an important role in how bullets "take" striations or markings during the firing event. Implications for the SCICLOPS system and future research are discussed.

The research object is to develop, verify and validate computational models of small arms ammunition bullets (calibre up to 12.7mm) and bullet-target interaction. Applying the developed computational models, the ballistic processes of small arms ammunition bullets have to be investigated and the main dynamic properties of such processes need to be obtained.

In the performance of law enforcement tasks, military forces frequently use expanding bullets. Such bullets are prohibited in international armed conflicts (IAC:s) by treaty, but in non-international armed conflicts (NIAC:s), the matter is regulated by the principle prohibiting means and methods of a nature to cause superfluous injury or unnecessary suffering (SIrUS), and possibly by an independent rule of customary international humanitarian law. This essay looks first to a proposed solution in which the law enforcement legal paradigm takes precedence, and finds such a solution incomplete and its application limited. It proceeds to look at the prohibition of expanding bullets in NIAC:s as an independent rule,exploring the formation of customary law, the evidence value of military manuals, expanding bullets as a war crime, and the ICTY Tadíc ruling. It finds the evidence of the existence of such a rule unconvincing. It then looks to principle of SIrUS and explores the best approaches for its interpretation and application. Ultimately, it argues that the military utility, in the form of stopping power and decreased risk of collateral injury, provided by expanding bullets is of such a scale and nature that the use of such bullets could reasonably be argued to pass the assessment as required by the principle. In light of this, the essay emphasises the need for treaty-based rules in order create effective weapons prohibitions, and that armed forces are still obliged to properly assess which set of rules govern the use of force.

In seeking to develop environmentally friendly lead-free non-toxic bullets, the research ballistically evaluated the performance of copper-jacketed handgun bullets containing a pure bismuth core. The lead was first removed from 140 grain HornadyTM XTP® bullets of 38 caliber (.357 diameter) by melting. The empty jackets were then refilled with pure bismuth, including the forming of a correctly sized hollow-point cavity. Due to the lower density of bismuth as compared to lead, the bismuth-cored bullets consistently weighed 125 gains. Conveniently this allowed direct comparison to commercially available 125 grain HornadyTM XTP® lead-cored bullets of 38 caliber. Both bismuth-cored and lead-cored versions of the 125 grain bullets had identical nose dimensions and jacket material, the only dimensional difference being the bullet length below the cannelure. Shooting took place at an outdoor range using a 357 Magnum RugerTM SP101® revolver with 3" barrel as the test weapon. FBI protocols were followed when firing through clothing, wallboard, plywood, steel plates and laminated glass. Wound paths and bullets were captured in ballistic gelatin, with data collected for velocity, penetration, expansion, and weight retention. Bismuth compared favorably with lead in all but the laminated glass test, where it under penetrated due to jacket separation.

This study examines small finds from the site of Chogha Gavaneh, Iran, including zoomorphic clay figurines, geometric-shaped objects, and sling bullets in order to deter-mine if they served an economic function during the Early Chalcolithic period (ca. 5000-4000 B.C.E.). A total of 104 animal figurines, sling bullets, and geometric-shaped objects have been found at Chogha Gavaneh. This research challenges previous archaeological interpretations of animal figurines that have interpreted them as being magical or lucky objects for hunting and religious rituals, or for use as game pieces, educational objects, or toys. Through the use of XRF (x-ray fluorescence spectrometry) analysis and the chaine opératoire approach, I suggest, contrary to the conventional wisdom, that some of these clay objects might represent another kind of social practice and may have had an economic function.

The paper examines lead isotope and trace element analysis in the context of a battlefield and their role in determining the course of the battle and categorizing the bullets within and to each participating side. It uses a theoretical framework with papers from both the archaeological and the forensic field. It concludes that trace element analysis has its criticism, especially from the forensic field, but can act as a complement to lead isotope analysis as it can give different answers from other parts of the bullet’s life cycle and should have a place in archaeology. The focus is on lead isotopes but concludes ICP-MS as a tool for examining bullets and other ammunition from archaeological battlefields is preferable. This is because of ICP-MS’s capability to analyse both lead isotope and trace elements. The paper also studies the ethical problems of using these methods and the answers they may give as a vessel for a discussion about what actions we are measuring with these methods.

This dissertation consists of five chapters, each of which focuses on various aspects of the forensic discipline of Firearms and Toolmarks. This dissertation for the most part attempts to highlight the exposure of projectiles to blood and the degradation over time of the fine detail, which is necessary for microscopic examination. This study should be of interest to students and qualified role-players in forensic science, the criminal justice system, the law community and the general population globally. Chapter 1 identifies the research problem and the necessary steps that were taken to ensure that the research methodol.ogy applied is relevant and reliable. Chapter 2 focuses on various factors that have to be considered in damage to bullets and investigation procedures that should be followed to ensure that physical evidence is preserved for submitting to a forensic science laboratory. Chapter 3 investigates the degradation effects of fired bullets exposed to various materials in a laboratory environment and the timelines associated with the degradation effects. Chapter 4 evaluates the examination procedures for fired bullets and the contributing factors that may influence the striation marks on bullets needed for microscopic examination. It also examines the scientific method used for firearm identification, and explores the admissibility of physical evidence in a court of law. The final chapter, Chapter 5 discusses the findings and recommendation of this research study. / Criminology / M. Tech. (Forensic Investigation)