AJUR Volume 15 Issue 4 (March 2019)

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AJUR Volume 15 Issue 4 (March 2019)

Links to individual manuscripts, abstracts, and keywords are provided below.


p.5 Mechanotransduction in Ischemic Cardiac Tissue: A Mechanical Bidomain Approach under Plane Stress
Justin Fee & Bradley J. Roth
ABSTRACT: Mechanotransduction is the process by which biological tissue translates mechanical forces and signals, such as those produced by strains or membrane forces, into biological reactions including cell remodeling, growth, and differentiation. While some analyses assume strain (the derivative of either the intracellular or extracellular displacement) as the cause of mechanotransduction, this paper assumes that differences between the intracellular and extracellular displacements, known as membrane force, result in mechanical forces acting on integrin proteins, causing mechanotransduction. The mechanical bidomain model is a two-dimensional mathematical representation that describes this behavior. Previous analyses describe mechanotransduction using plane strain, which assumes zero displacement in the z-direction. This analysis uses plane stress, which assumes zero stress in the z-direction, to describe where mechanotransduction occurs in comparison to plane strain models. A sample of healthy tissue with a circular ischemic region with no active tension in the center is analyzed using numerical methods. Fixed and free boundary conditions are implemented. Under fixed conditions, the membrane force was largest in the ischemic border zone and zero everywhere else. However, the strain was found to be largest in the ischemic region. Under free conditions, the membrane force was largest on the vertical edges and in the ischemic border zone. The strain was found to be nearly zero in the ischemic region and ranged up to 10%throughout the tissue. In conclusion, this paper found that both plane strain and plane stress predict a membrane force in the ischemic border zone, but the distribution of individual displacements and strain vary according to each model. These results are significant in determining which model is most appropriate to use in predicting how mechanical forces affect cellular remodeling when analyzing thin monolayers of tissue.
KEYWORDS: Mechanotransduction; Plane Stress; Tissue Engineering; Mechanical Bidomain Model; Biomechanics; Strain; Intracellular Cytoskeleton; Extracellular Matrix; Ischemia; Finite Differences

p.17 Potential Consequences of Hosting an Ant-tended Treehopper, Publilia concava, for Tall Goldenrod, Solidago altissima
Luke J. McCartin, Nabil A. Nasseri,
& Alison K. Brody
ABSTRACT: In ant-hemipteran mutualisms, ‘tending’ ants indiscriminately defend hemipterans from other arthropods, protecting mutualism-hosting plants from defoliating herbivores in some cases. Censuses of a treehopper, Publilia concava, observations of tending ants, and measurements of leaf area were conducted on tall goldenrod, Solidago altissima, over the course of a summer at a field site in central Vermont. Hosting ant-tended treehopper aggregations had no effect on leaf area or the ability for goldenrod to flower, suggesting that in the absence of an herbivore outbreak this mutualism is neither necessary nor inherently detrimental for goldenrod. These findings support the hypothesis that the net consequence of the ant-hemipteran mutualism for its host plant depends on the costs of hemipteran damage, and the benefits of ant defense from other arthropods.
KEYWORDS: Ants; Mutualism; Ant-plant Interactions; Treehopper; Hemiptera; Ant-hemipteran Mutualism

p.23 Using Smart Glasses for Facial Recognition
Gabriella A. Mayorga, Xuan Do, & Vahid Heydari

ABSTRACT: Facial recognition is one of the most promising applications of smart glasses and can help many organizations become more efficient. For example, police traditionally identify criminals by manually going through pictures in a database which makes face matching a slow process. However, with the combination of facial recognition software, smart glasses, and databases, the police can quickly scan through multiple databases of faces to find a match. The police would also be able to spot criminals in crowds, identify unknown victims at crime scenes, retrieve background information on individuals, and verify if someone is a missing person. The Transportation Security Administration (TSA) can also use this combination to identify potential terror suspects or verify the identity of travelers. Lastly, academia can benefit from these tools by being able to identify individuals at events (e.g. conferences) and display relevant information about them. The goal of this project is to write an Android program that takes a photo via Google Glass, compares it with a predefined sample database held within the smartphone, and outputs information based on its analysis. The results are displayed with an accuracy acceptance level to the user both on their Android smartphone and on their Google Glass.
KEYWORDS:Face Detection; Facial Recognition; Smart Glasses; Android Smartphone; Mobile Application; Google Glass; Java; SQLite

p.37 Sexual Assault Among College Students Attending a Historically Black College/University
Deshawn Collington, Markea Carter, Aliyah Tolliver, & Jocelyn Turner-Musa
ABSTRACT: Sexual assault constitutes a significant public health problem on college campuses including historically Black colleges and universities (HBCU). Recent research suggests that sexual assault is increasing on college campuses.  However, there are few studies examining the prevalence and risk factors for sexual assault at HBCUs. To address this gap, the current study examined the prevalence, correlates, and outcomes of sexual assault at an HBCU. Participants in the study were 264 undergraduate students from an HBCU in the mid-Atlantic region. The majority of participants were female (71%), African American (91%), and seniors (41%). After providing informed consent, participants completed a Climate Assessment survey administered by the university’sOffice of Diversity. Findings revealed that since starting college about 20% of students experienced sexual contact without consent. Of those sexually assaulted, 20% reported they were incapacitated or under the influence of alcohol (15%) at the time of the assault. About 17% of those assaulted experienced a physical injury and/or poor mental health outcomes (e.g., anxiety, depression, flashbacks). Participants reported not disclosing information of their assault due to embarrassment, afraid of retaliation from the perpetrator, believing it was a private matter. Close friends were more likely to be told about sexual assault. The study supports the need to address sexual assault on HBCU campuses through strong prevention and intervention programs and to address barriers to reporting.
KEYWORDS: Sexual Assault; HBCU; College Students; Prevalence; Risk Factors; Outcomes; Barriers of Reporting; Sexual Assault Climate Assessment Survey 

p.47 Examining Collection Biases Across Different Taxonomic Groups: Understanding How Biases Can Compare Across Herbarium Datasets
Jordan Williams & Katelin D. Pearson
ABSTRACT: Specimen-based data are an invaluable resource for an increasing diversity of scientific fields, including global change biology, ecology, evolution, and genetics; however, certain analyses of these data may be limited by the non-random nature of collecting activity. Geographic, temporal, and trait-based collecting biases may consequently affect the understanding of species’ distributions, obviating the need to determine what biases exist and how they may impact further analyses. Trait-based biases were examined in herbarium specimen records of two abundant and diverse families (Asteraceae and Fabaceae) in a well-collected and digitized region (California) by comparing geographic-bias-adjusted simulations of random collections to actual collecting patterns. Collecting biases were fairly similar between families for a number of traits, such as a strong bias against collecting introduced species, while seasonal collecting biases showed a peak in activity in the Spring for both families. However, while there was only a dip in the fall for Asteraceae, Fabaceae were seriously under-collected for the majority of the year. These results demonstrate that significant collecting biases exist and may differ depending on the dataset, highlighting the importance of understanding the dataset and potentially accounting for its sampling limitations.
KEYWORDS: Biodiversity; Natural History Collection; Sampling Bias; Biodiversity Specimens; iDigBio; Botanical Databases; Plant Traits

p.55 Valveless Fluid Pumping via Zero-Net-Momentum Injection
Johnathan Cace
ABSTRACT: A novel mechanical method to valvelessly pump fluid has been developed using zero-net-momentum injection via a syringe and a tilted canister that function together as a periodic mass source and sink. Unlike previously discovered valveless pumping methods, this method does not require any elastic tubing and can be achieved by simple manual actuation, making it a simpler and less expensive valveless alternative. The flow rate is highly dependent on the frequency at which momentum is injected and retracted from the system. The direction of the flow can be changed by switching the location of the syringes. This pumping paradigm has potential applications in microfluidics where elastic channels are difficult to fabricate and valveless fluid actuation methods are preferred.
KEYWORDS: Valveless Pumping; Momentum Injection; Microfluidics; Fluid Mechanics; Windkessel Effect

p.61 Sex Bias in Tuberculosis in the Developing World
Sophie Shaw & Kevin J Purdy
ABSTRACT: Tuberculosis (TB), the most deadly global single organism infectious disease, kills nearly twice as many men as women. Understanding the factors that drive this bias in TB mortality is an important aspect of the global effort to reduce the enormous burden of this disease in the developing world. One third of the world’s population is estimated to be infected TB, with Low and Middle Income Countries (LMIC) bearing the greatest disease burden. In LMIC sex bias in TB is influenced by sociocultural, behavioural as well as biological factors, with dynamic interactions between reporting variables, other confounding variables and physiological mechanisms, which each influence one another to produce the male-biased sex ratio observed in TB transmission, prevalence and mortality. While confounding factors are addressed in the existing global drive to tackle TB it is the biological aspects of sex bias in TB that present specific challenges for diagnosis and treatment in men and women as they potentially influence future immunological-based interventions to treat TB.
KEYWORDS: Tuberculosis; Low and Middle Income Countries; Sociocultural Influences; Behavioural Bias; Biological Sex Bias; Reporting Bias; TB and Sex Hormones

p.71 Obstructive Sleep Apnea is Associated with Longitudinal Increases in Amyloid Burden in Elderly Mild Cognitive Impairment Individuals
Megan Hogan, Amanda Shim, Umasabor-Bubu Ogie Queen, Mukhtar Fahad, & Omonigho Michael Bubu
ABSTRACT: Cross sectional analysis has shown an association between Obstructive Sleep Apnea (OSA) severity and Aβ burden using amyloid-PET among Mild Cognitive Impairment (MCI) patients. However, whether OSA accelerates longitudinal increases in amyloid beta (Aβ) burden in MCI patients is presently unclear.Study participants included a total of 798 subjects with a diagnosis of MCI and were a subset of the ADNI cohort (adni.loni.usc.edu). OSA was self-reported and participants were labeled either as OSA+ or OSA−. Aβ burden was determined by florbetapir SUVRs. To test whether OSA is associated with the rate of change in Aβ data longitudinally, multilevel mixed effects linear regression was used to fit the models with randomly varying intercepts and slopes allowing dependence on OSA status. The final model was adjusted for age, sex, body mass index, education, CPAP use status, history of respiratory disease, hypertension, diabetes, and history of cardiovascular disease. A significant variation in the change (slope) in Aβ volumes over time was seen (p<.0001). The covariance between the baseline Aβ level and Aβ volume change over time indicated that OSA subjects experienced greater mean change differences in brain Aβ volumes over time (p < .0001). The rate of change in Aβ deposition also varied significantly across OSA groups over the follow-up period.Obstructive Sleep Apnea possibly facilitates longitudinal increases in amyloid burden in elderly Mild Cognitive Impairment individuals. Further research examining mechanisms underlying effects of OSA on the longitudinal increases in Aβ burden is needed.
KEYWORDS: Obstructive Sleep Apnea; OSA; Amyloid; Mild Cognitive Impairment; MCI; Elderly

p.79 It Gets Better with Time: The Perception of Stigma Among Older Adults with Chronic Physical Illness and in Recovery from Mental Health Condition
Angela J. Johnson & Kyaien O. Conner
ABSTRACT: Older adults are a vulnerable population who are more susceptible to developing mental health conditions, and the symptoms are often exacerbated by the co-occurrence of various physical health complications. Despite available evidence-based interventions, many older adults neglect to utilize mental health services, due to the stigmatization of mental health conditions. Limited research has focused on the unique experiences of older adults who have overcome the adverse effects of stigma, have sought help for their mental health condition and are currently in recovery. There are even fewer studies that have addressed perceptions of stigma among older adults in recovery from a mental health condition who are currently living with a chronic physical illness. The present study investigated the unique experiences of seeking professional mental health services and the perceptions of stigma among nine older adults living with a chronic physical illness and currently in recovery from a mental health condition utilizing semi-structured interviews. Through an in-depth thematic analysis of the data, four over-arching themes were identified: Resilience from the Stigma of a Mental Illness, Community Engagement, Cultural Barriers and Social Support System. Findings from the current study suggest that older adults who have previously experienced a mental health condition and were able to overcome the stigma of their condition, were more likely to seek professional help. Additionally, engaging in community engagement programs to help other older adults who are currently experiencing acute mental health conditions seemed to reduce perceptions of stigma and positively impacted participants self-esteem and overall outlook on life.
KEYWORDS: Stigma; Perception; Older Adults; Mental Health Condition; Co-Occurring Disorders