College of Science

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https://hdl.handle.net/1920/2869

The study of science is a critical part of higher education. The College of Science promotes a vibrant and dynamic environment of learning and inquiry, and offers unique opportunities for academic and research collaborations across the university, region, nation, and the world.

Our approach to science education is centered around the sharing and cultivation of critical thinking, curiosity, skills, and commitment to the advancement of knowledge. Our faculty members use novel pedagogical approaches to challenge and prepare students to become independent and creative members of the scientific community and society.

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Now showing 1 - 20 of 348
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    A Comparative Analysis of Casting Materials on Developed Latent Prints
    (2020) Brock, Jenny F.
    The drive to preserve and collect latent prints has led to the creation of innovative products and technologies. However, because of the increasing variety of the implements, supplementary research was necessary to ensure appropriate application of these products dependent on circumstances, environments, and availability. Further, crime scene technicians and departments, who rely on experience and accessibility of materials, also need current information on product capabilities and limitations. This research compared AccuTrans, First Contact polymer solution, and Elmer’s glue as casting materials applied to latent prints developed with dual-use black powder. The latent prints samples (n=60) were deposited on either flat or curved substrates, and then preserved with one of the three casting materials. Evaluation of the collected latent prints included: whether friction ridge detail was present, how many individual characteristics could be observed with a restriction of 10, and how many levels of friction ridge detail were represented. The results of this study indicated that no matter which casting material was selected, there was no significant variation in the ability of the materials to perform (p=.794) and successfully collect a developed latent print for examination on certain substrates (p=.462). Individually the casting materials had observable strengths and weaknesses such as short or extended dry times, deformation after collection, and ease of collection.
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    A Comparative Evaluation of Kits for Seminal Fluid Detection
    (2024-05) Sperling, Anaya; Knight, Kelly
    Seminal fluid detection kits are commonly used within the forensic science field to determine whether an unknown sample contains semen. The ability to correctly identify seminal fluid in any criminal cases involving bodily fluids is of the utmost importance. The ABACard p30 kit is most commonly used in forensic DNA laboratories to detect semen. This study “A Comparative Evaluation of Kits for Seminal Fluid Detection” will compare the ABACard p30, RSID - Semen, and SERATEC Semiquant PSA kit to the Bluestar Identi-PSA kit which is newer to the field. Bluestar, ABA, and SERATEC kits test for the presence of prostate specific antigen (PSA) which is the protein present in semen. On the other hand, RSID - Semen detection kit tests for semenogelin which is the protein that is found in ejaculated semen and is responsible for sperm immobilization in the seminal coagulum. To evaluate the specificity of these kits, breastmilk, saliva, and blood will also be tested in duplicate. Labor intensity, cost, and sensitivity will also all be compared between the four kits. Sensitivity will be evaluated by testing a series of dilutions of semen in duplicate from 1:10 to 1:100,000. It is expected that all four kits will be equally effective (creating true positives) in detecting semen, however, there will be differences in labor intensity and cost. It is also anticipated that a potential false positive with the breastmilk will happen since previous research has reported the detection of prostate specific antigen or semenogelin in breastmilk. The result of a positive test from breastmilk would pose the question of whether said kit would be deemed to be as reliable as stated. It is expected to conclude that between the four kits: Bluestar Identi-PSA, ABACard p30, RSID - Semen and SERATEC Semiquant PSA, each will yield different results when it comes to specificity and sensitivity.
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    A Model Study of the Response of Mesospheric Ozone to Short-Term Solar Ultraviolet Flux Variations
    (American Geophysical Union, 1990-12-20T00:00:00Z) Summers, Michael E.; Strobel, D. F.; Bevilacqua, R. M.; Zhu, Xun; DeLand, M. T.; Allen, M.; Keating, G. M.
    An investigation is conducted in order to determine the relative importance of several modeled processes in controlling the magnitude and phase of the mesospheric ozone response. A detailed one-dimensional modeling study of the mesospheric ozone response to solar UV flux variations is conducted to remove some of the deficiencies in previous studies. This study is also used to examine specifically the importance of solar zenith angle, self-consistent calculation of water vapor abundance, and temperature feedback with a nonlocal thermodynamic equilibrium radiation model. The photochemical model is described, and the assumptions made for the purpose of comparing model results with the observed ozone response obtained from a statistical analysis of Solar Mesosphere Explorer data (Keating et al., 1987) are discussed. The numerical results for the theoretical ozone response are presented. The results of selected time-dependent calculations are considered to illustrate the degree to which a relatively simple model of the mesosphere is able to capture the major characteristics of the observed response.
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    A Quantitative Study On Extraction Versus Direct Amplification Of Touch DNA Samples
    (2022-05) Basrawi, Jude
    Touch DNA, also known as Trace DNA, is an important aspect of criminal investigations, as the perpetrator is unaware of the DNA they have left behind. While there are multiple ways to extract touch DNA, it has been established that direct amplification provides exemplary results. Direct Amplification is the process of analyzing the samples by amplifying them without extraction or quantitation. However, there is no measure on how much information direct amplification provides as opposed to other widely used methods including standard extraction procedures. This study aimed to look at the differences in information obtained when processing a touch DNA sample using standard extraction procedures versus a direct amplification approach. Understanding the scope of information collected by direct amplification versus standard extraction procedures can be used to facilitate new protocols for processing touch DNA. This study focused on collecting touch DNA samples from 20 volunteers and processing the DNA using two methods. In the first half of the study, half of the samples were extracted, quantified, and amplified using the InnoXtractTM, InnoQuantTM and InnoTyperTM kits, respectively, from InnoGenomics, LLC. The next part of the study included adding swabs to be directly amplified using the InnoTyperTM 21 kit. Rather than the standard extraction protocol, this method included placing the swab heads directly into the PCR tubes for amplification. Samples undergoing direct amplification are expected to show more information due to the fact that standard extraction protocols often result in loss of DNA. Data generated from capillary electrophoresis was compared by reviewing the allele peak heights. Samples exhibiting “real” and representative peaks were further reviewed to determine if the peaks were real or due to artifacts such as noise. The research findings may lead to revised protocols that can be applied to difficult sample types, such as touch DNA, which often result in partial DNA profiles that often contain very little information.
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    Abundance and Size of Gulf Shrimp in Louisiana's Coastal Estuaries following the Deepwater Horizon Oil Spill
    (Public Library of Science, 2014-10-01) van der Ham, Joris L.; de Mutsert, Kim
    The Deepwater Horizon oil spill impacted Louisiana's coastal estuaries physically, chemically, and biologically. To better understand the ecological consequences of this oil spill on Louisiana estuaries, we compared the abundance and size of two Gulf shrimp species (Farfantepeneus aztecus and Litopeneus setiferus) in heavily affected and relatively unaffected estuaries, before and after the oil spill. Two datasets were used to conduct this study: data on shrimp abundance and size before the spill were available from Louisiana Department of Wildlife and Fisheries (LDWF). Data on shrimp abundance and size from after the spill were independently collected by the authors and by LDWF. Using a Before-After-Control-Impact with Paired sampling (BACIP) design with monthly samples of two selected basins, we found brown shrimp to become more abundant and the mean size of white shrimp to become smaller. Using a BACIP with data on successive shrimp year-classes of multiple basins, we found both species to become more abundant in basins that were affected by the spill, while mean shrimp size either not change after the spill, or increased in both affected and unaffected basins. We conclude that following the oil spill abundances of both species increased within affected estuaries, whereas mean size may have been unaffected. We propose two factors that may have caused these results: 1) exposure to polycyclic aromatic hydrocarbons (PAHs) may have reduced the growth rate of shrimp, resulting in a delayed movement of shrimp to offshore habitats, and an increase of within-estuary shrimp abundance, and 2) fishing closures established immediately after the spill, may have resulted in decreased fishing effort and an increase in shrimp abundance. This study accentuates the complexities in determining ecological effects of oil spills, and the need of studies on the organismal level to reveal cause-and-effect relationships of such events.
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    Age-at-death estimations using cementochronology in thermally altered teeth
    (2021-04) Weaver, Ryen L.
    Macroscopic age-at-death estimations provide age ranges that give broad and often insufficient insight to an individual’s chronological age. Accurate age estimations can become more complex for a forensic anthropologist if the unknown individual has been subjected to extreme heat from an assortment of scenarios that include but are not limited to structure fires, airplane crashes, automobile accidents, and attempts to conceal evidence of homicide. Due to their high mineral content and sequestered placement in the jaw, teeth have the ability to be one of the best-preserved human tissue remains in extreme heat situations (Beach, Passalacqua, & Chapman, 2015). Cementochronology utilizes the cementum, the mineralized covering of a tooth root, as an aid in estimating an individual’s age (Colard, et al., 2015). The utilization of cementochronology is one of the most accurate ways to estimate age-at-death due to the countable cementum annulations found in the cross-sections directly correlating to the individuals age (Wittwer-Backofen, 2004). This study aims to provide an in-depth analysis of thermal alteration to human teeth by various accelerants when utilizing the cementochronology method to build a biological profile. The sample in this study consists of 36 teeth from both male and female donors from all odontological positions ranging in age from 9-87 years. Three accelerants with varied volumes were used to determine if the readability of cementum annulations can still remain accurate after alteration. Results indicated that the type of tooth had significant impact on the ability to count annulations. Annulations were able to be read and estimated after alteration with all three accelerants used in this study. However, acetone yielded the lowest results with the most severe alterations. A novel formula was developed to help approximate the amount of cementum annulations found within each sample. This formula was found to yield estimated tooth cementum annulations that were highly correlated with the actual ages of the individuals from whom the samples were from. After thermal alteration of teeth with accelerants it was found that cementochronology is an accurate and helpful tool for estimating age-at-death in unknown individuals.
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    Age-Independent Rise of Inflammatory Scores May Contribute to Accelerated Aging in Multi-Morbidity
    (Impact Journals, LLC, 2015-02-10) Stepanova, Maria; Rodriguez, Edgar; Birerdinc, Aybike; Baranova, Ancha
    Aging is associated with an increase in a chronic, low-grade inflammation. This phenomenon, termed “inflammaging” is also a risk factor for both morbidity and mortality in the elderly. Frequent co-occurrence of chronic diseases, known as multi-morbidity, may be explained by interconnected pathophysiology of these conditions, most of which depend on its inflammatory component. Here we present an analysis of the U.S. National Health and Nutrition Examination Survey data collected between 1999 and 2008, for the presence, and the number, of chronic diseases along with HDL-cholesterol, C-reactive protein, white blood cell count, lymphocyte percent, monocyte percent, segmented neutrophils percent, eosinophils percent, basophils percent, and glycohemoglobin levels. Importantly, even after adjustment for age and BMI, many inflammatory markers continued to be associated to multi-morbidity. C-reactive protein (CRP) levels and Glasgow Prognostic Score (GPS) were most dramatically increased in parallel with an accumulation of chronic diseases, and may be utilized as multi-morbidity predictors. These observations point at background inflammation as direct, age-independent contributor to an accumulation of the disease burden. Our findings also suggest a possibility that systemic inflammation associated with chronic diseases may explain accelerated aging phenomenon previously observed among the patients with heavy disease burden.
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    Album of flash animations, demonstrating oscillations, waves, and phasors
    (2008-01-08T03:08:08Z) Ceperley, Peter
    A album of 24 flash animation illustrating various principles of the physics of oscillations, waves, and phasors. The album shows an image of each animation and has various links to each.
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    An Ecological Study of Gunston Cove - 2011
    (2012-11-27) Jones, R. Christian; de Mutsert, Kim
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    An Ecological Study of Gunston Cove 2008
    (2009-12) Jones, R. Christian; Kraus, Richard
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    An Ecological Study of Gunston Cove 2009
    (2010-12) Jones, R. Christian; Kraus, Richard
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    An Ecological Study of Gunston Cove 2010
    (2011-12-13) Jones, R. Christian; Kraus, Richard
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    An Ecological Study of Gunston Cove 2017
    (2018-12) Jones, R. Christian; Mutsert, Kim de; Fowler, Amy
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    An Ecological Study of Hunting Creek 2013
    (2014-04-09) Jones, R. Christian; de Mutsert, Kim; Foster, Gregory D.
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    An Ecological Study of Hunting Creek 2015
    (2016-12-04) Jones, R. Christian; de Mutsert, Kim; Jonas, Robert; Huff, Thomas
    Hunting Creek is an embayment of the tidal Potomac River located just downstream of the City of Alexandria and the I-95/I-495 Woodrow Wilson bridge. This embayment receives treated wastewater from the Alexandria Renew Enterprises wastewater treatment plant and inflow from Cameron Run which drains most of the Cities of Alexandria and Falls Church and much of eastern Fairfax County. Hunting Creek is bordered on the north by the City of Alexandria and on the west and south by the George Washington Memorial Parkway and associated park land. Due to its tidal nature and shallowness, the embayment does not seasonally stratify vertically, and its water is flushed by rainstorms and may readily mix with the adjacent tidal Potomac River mainstem. Beginning in 2013 the Potomac Environmental Research and Education (PEREC) in collaboration with Alexandria Renew Enterprises (AlexRenew) initiated a program to monitor water quality and biological communities in the Hunting Creek area including stations in the embayment itself and the adjacent river mainstem. This document presents study findings from 2015 and compares them with 2013 and 2014 data. In addition special studies were conducted on anadromous fish usage of Hunting Creek and Cameron Run, Escherichia coli levels in Hunting Creek and tributaries, and micropollutant levels in sediments and waters of Hunting Creek and Cameron Run.
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    An Introduction to Applications of Access
    (Network Design Lab, University of Sydney, 2021) Ermagun, Alireza; Levison, David
    From its source Latin accedere, the assimilated form of ad and cedere, access means "to approach." It conveys the "habit or power of getting into the presence of someone or something." The contemporary meaning differs, but has not strayed too far from the origin. Access means freedom, possession rights, and other means of benefiting from resources. It offers neither what people will do, nor what people want to do, rather what people could do. Transport access is a product of mobility and place and immediately relates to the transport network and the relative location of human activities and housing. However, there is still confusion among engineers and planners in differentiating access from mobility. Mobility indicates one’s ability to move easily. It encompasses both speed and travel time by defining how far one can travel in a given time. Access, however, is concerned with the opportunities that can be reached in a given time.
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    An unshielded radio-frequency atomic magnetometer with sub-femtoTesla sensitivity
    (AIP Publishing LLC, 2014-12-31) Keder, David A.; Prescott, David W.; Conovaloff, Adam W.; Sauer, Karen L.
    We demonstrate a radio-frequency potassium-vapor magnetometer operating with sensitivities of 0.3 fT/√Hz at 0.5 MHz and 0.9 fT/ √Hz at 1.31 MHz in the absence of radio-frequency and mu-metal or magnetic shielding. The use of spatially separated magnetometers, two voxels within the same cell, permits for the subtraction of common mode noise and the retention of a gradient signal, as from a local source. At 0.5 MHz the common mode noise was white and measured to be 3.4 fT/ √Hz; upon subtraction the noise returned to the values observed when the magnetometer was shielded. At 1.31 MHz, the common mode noise was from a nearby radio station and was reduced by a factor of 33 upon subtraction, limited only by the radio signal picked up by receiver electronics. Potential applications include in-the-field low-field magnetic resonance, such as the use of nuclear quadrupole resonance for the detection of explosives.
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    Anadromous Fish Survey Cameron Run 2015
    (2016-12-04) de Mutsert, Kim
    The focus of the Cameron Run fish survey is river herring, the collective name of blueback herring and alewife. River herring populations have declined drastically over their range, spurring conservation efforts since 1970, which have been intensified since 2005 with implementation of moratoria. Identifying all areas used as spawning habitat by alewife and/or blueback herring is an important component of their conservation. Since 1988, George Mason University researchers have focused a monitoring program on the spawning of these species in other tributaries such as Pohick Creek, Accotink Creek, and, less regularly, Dogue Creek. With this study Cameron Run is added, which has not been monitored for presence of river herring or other anadromous species by either George Mason or other fisheries biologists before the start of this study in 2013 (Jim Cummins, pers. comm.). Our 2013 survey provided the first confirmation of Cameron Run as River Herring spawning habitat (Allan Weaver, VDGIF, pers. comm.). Use of Cameron Run by river herring upstream from where the effluent of Alexandria Renew Enterprises enters Cameron Run signifies that the effluent does not deter river herring from using Cameron Run as spawning habitat. In 2014 we moved the collection site approximately 500 m downstream (still above the Alexandria Renew Enterprises effluent), which increased our catches, and allows us to estimate the size of the spawning population. The new location proved successful and will remain the collection site for any subsequent surveys.