The Impact of Submersion on the Quantification of Host and Bacterial DNA

The Impact of Submersion on the Quantification of Host and Bacterial DNA Grace Sprouse, Depts. of Forensic Science and Chemistry, with Dr. Catherine Connon, Dept. of Forensic Science and Dr. Baneshwar Singh, Dept. of Forensic Science Microorganisms, which contribute to carrion decomposition, can be used as a clock to estimate time since death. There has been an increase in the amount of studies looking into how bacteria can be used to estimate time since death. Much of this research has been aimed at examining how microorganism communities can be used to determine post mortem interval (PMI) in land environments, for example, research completed by Finley et all1, which focused on how microorganism communities differ on corpses and in the soil surrounding the body. Finley et all1 research was used to see how these quantities can be used to determine PMI. However, the comparison between 16S rDNA and nDNA has not been explored. Changes in bacterial DNA quantity may inform researchers on feasibility of using bacteria on remains to estimate the postmortem interval (PMI) and postmortem submersion interval (PMSI). It could also provide insight regarding bacteria: host nDNA ratio, guiding decisions on best methods for victim ID (i.e., microbe based PMSI estimation or DNA profile development). Therefore, this research sought to compare bacterial DNA (16S rDNA) to host nuclear DNA (nDNA) recovered from long-term submerged skeletal elements (e.g., rib and scapula) using two different extraction methods (e.g., organic-phenol chloroform and solid-phase). Using 10” x 10” cages, each containing five ribs and scapulae, samples were submerged in a freshwater lake (e.g., Henley Lake) and river (e.g., James River). Approximately ca. 250 accumulated degree days (ADD), one cage was collected, totaling nineteen lake and twenty-four river collections. The resulting 364 samples underwent DNA extraction (e.g., organic phenol-chloroform and ChargeSwitch®) before being analyzed via agarose gel electrophoresis (1.0% agarose gel). Gel visualization was performed to evaluate the separation of DNA bands and assess the quality of the extraction method used on each sample. In preparation for Real-Time qPCR quantification, standard curves were performed. Using the ABI 7500, each sample will be quantified twice, once using bacterial primers focusing on variable region 4 of 16S rDNA and once utilizing FH1733 porcine nuclear primers2. This section of the research will continue when the university reopens.https://scholarscompass.vcu.edu/uresposters/1350/thumbnail.jp

Karst and groundwater in northeastern Coahuila: An Edwards Aquifer mirror

The northeastern corner of the Mexican state of Coahuila contains some of the most extensive limestone outcrops in the country, yet the karst and groundwater have seen relatively little investigation. The western (recharge) portion of the area contains ridge tops of Lower Cretaceous rocks over 1500 m in elevation, which slope down to the east and south to plunge underneath less karstic Upper Cretaceous outcrops. This represents a confined aquifer zone where wells can flow under artesian pressure. In this respect it resembles the Edwards Aquifer across the Rio Grande in Texas, with similar carbonate lithologies and karst components. Over 60 caves have been explored in the area, most since the year 2000. Upland portions of the recharge zone contain vertical caves that likely contribute to aquifer recharge, although numerous seep-spring caves in canyon walls disgorge some water prematurely. The canyons themselves are major rechargers, exemplified by El Abra, a horizontal stream cave that is the longest in Coahuila at 1841 m in length. In the lower part of the recharge zone close to the artesian zone, there are a number of caves which are estavelles. These have large funnel-shaped sinkhole entrances that slope down to pits, dropping up to 90 m to flowing streams. These normally take water, but during times of heavy rains in the recharge zone they can become springs.Integrative Biolog

Engine Hydraulic Stability

An analytical injector model was developed specifically to analyze combustion instability coupling between the injector hydraulics and the combustion process. This digital computer dynamic injector model will, for any imposed chamber of inlet pressure profile with a frequency ranging from 100 to 3000 Hz (minimum) accurately predict/calculate the instantaneous injector flowrates. The injector system is described in terms of which flow segments enter and leave each pressure node. For each flow segment, a resistance, line lengths, and areas are required as inputs (the line lengths and areas are used in determining inertance). For each pressure node, volume and acoustic velocity are required as inputs (volume and acoustic velocity determine capacitance). The geometric criteria for determining inertances of flow segments and capacitance of pressure nodes was set. Also, a technique was developed for analytically determining time averaged steady-state pressure drops and flowrates for every flow segment in an injector when such data is not known. These pressure drops and flowrates are then used in determining the linearized flow resistance for each line segment of flow

The Gambia’s unsurprising renunciation of the ICC, or the so-called “International Caucasian Court”

LSE’s Ian Sprouse explains the decision of The Gambia to withdraw from the International Criminal Court through a retrospective on the rule of President Yahya Jammeh

School District Superintendents\u27 Response to Ethical Dilemmas: A Grounded Theory

Ethical dilemmas, situations involving a conflict between values or principles, often arise when employees of school districts violate laws or professional codes of behavior. Ethical dilemmas also occur when there are inequities in educational programming, resulting in missed opportunities for students. This qualitative study, conducted with the grounded theory research methodology, analyzed school district superintendents\u27 responses to ethical dilemmas experienced in the course of their professional career. Critical influences on the decision-making process and the ethical frameworks utilized by participants were examined. A \u27Model of Superintendents\u27 Responses to Ethical Dilemmas\u27 was developed and participants\u27 stories were used to elucidate the model. The tacit knowledge shared by participants in the study can be helpful to practicing and aspiring school district superintendents as they seek to become more attuned to the pressures and barriers that influence the ethical decision-making process and help them to become more aware of their own approach to ethical decision-making