Heading for a breakdown: Assessing evolution through the hybridization of two sexual systems

Hybridization is an important evolutionary pathway that has contributed to the world’s vast biodiversity. In plants, hybridization is known to be an important mechanism for speciation, phenotypic divergence, and changes in reproductive systems. Solanum species present an ideal system to investigate how hybridization between two different sexual systems impacts the reproductive and phenotypic biology of the hybrid progeny. Hybrids were acquired from crosses between Australian species Solanum dioicum (dioecious) and S. ultraspinosum (andromonoecious). The only successful hybrids from the original crosses were those derived from S. diocium as the pollen donor and S. ultraspinosum as the pollen recipient. Due to strong maternal effects, all the F1 hybrids resembled S. ultraspinosum, so all F1 plants were andromonoecious. To assess phenotypic differences between the hybrids and their parents, I collected morphometric data and used ImageJ software. A series of statistical analyses were done using R. A principal component analysis confirmed that the hybrids were distinct from both parents, but were most similar to S. ultraspinosum. The F2 hybrids appear to demonstrate variability in inflorescence architecture, which may be suggestive of a change in sexual system, although further analysis is needed. In attempts to create an F3 hybrid generation, nearly all of our crosses have failed—suggesting that a hybrid breakdown is occurring. To determine where the breakdown is occurring, I will be employing a technique using fluorescent microscopy. Overall, my study will promote a better understanding of hybridization—a driving force of plant speciation—which has broad impacts for the long-term viability of plant species.

Continue reading Diamanda Zizis »

ProPANE Notetaking Assistive Technology
The Propane project is a collaborative research project between Electrical & Computer Engineering and Education at Bucknell University. Our goal is to develop an assistive technology that will support note taking for college students with learning disabilities (LD) and English Language Learners (ELLs) in the lecture-based classroom to improve their content learning and academic performance. While research has shown that effective note taking leads to better performance and content mastery, students with LD and ELLs may struggle with this task in lecture-based classrooms. The purpose of the project is to reduce students’ cognitive load and free students’ working memory space to absorb lecture content.
Our approach is to create a smartphone application that will be used by the student to capture the lecture. The student will submit a video of the lecture and the application will use various image processing techniques and segmentation algorithms to extract the key information from the lecture. The extracted information is returned to the student for them to further review and or annotate. The extraction of the targeted information is a unique aspect of this project and presents major technical challenges but can potentially support effective and efficient note taking. By allowing the student to focus on the lecture and not note taking, it allows them to engage in other ways and use their working memory space on activities and discussion.

Continue reading Bangyan Li »

Visual Characterization of Aponeurosis Microstructure

Aponeurosis is a tendinous sheath-like tissue found in many muscle-tendon units that covers the muscle belly and transitions into tendon. Little research has been done to understand how collagen fiber microstructure contributes to aponeurosis stiffness and mechanical function. The goal of this study was to use scanning electron microscopy (SEM) to characterize the microstructure of aponeurosis tissue be comparing waviness values measured in unstretched and stretched tissue. It is hypothesized that the waviness of the collagen fibers will decrease after tissue has been stretched. Porcine shoulder tissue was dissected to obtain 40×10 mm specimens. Unstretched samples (n=10) were fixed in 10% formaldehyde, while stretched samples (n=10) were fixed at five percent strain. Images were taken at 50, 100, 1k, and 3.5k magnification. Waviness of the stretched and unstretched aponeurosis was quantified as the ratio of the true length of the collagen fiber to the tangent of two endpoints of that same collagen fiber. Aponeurosis exhibited a hierarchical structure, similar to that of tendon or ligament, with collagen-rich fascicles, fibers, and fibrils. Waviness in the collagen fibers was observed at lower magnifications (100 μm), while at higher magnifications the sheet-like structure of the collagen fibrils was seen (1,000 μm). Unstretched tissue exhibits a high degree of waviness or collagen crimp (1.17 ± 0.21) compared to tissue that has been fixed under a five percent stretch (1.05 ± 0.06, p = 6.615e-08). Future work will include using computational modeling to study the effect of collagen structure on aponeurosis mechanics.

Continue reading Olivia Dyer »

Development of Guidelines for Playground Surfacing Based on Field Testing

Many different playground surfaces are used in the United States for fall-related injury protection. These surfaces are categorized as unitary or loose-fill and there is a strong interest in quantifying their performance to ensure they are meeting head-injury safety standard ASTM F1292, which dictates a compliant head injury criteria (HIC) metric of less than 1000.

Analysis for this study was performed from a randomized sample of 103 public playgrounds across the United States, which was collected by the National Program of Playground Safety on behalf of the United States Consumer Product Safety Commission (CPSC). Field testing data included analysis of safety surfacing, including fall height, depth of the surface material, and resulting head injury criteria (HIC) score to interpret performance trends in ASTM-compliant HIC scores.

The results indicate for all materials that as the fall height increases, the surfacing’s performance decreases. A similar trend applies for surface depth—as the surface depth decreases, the surfacing’s consistency decreases. While all the surfaces display similar overall trends, there are a few differences as well. Some surface materials appear to reach a fall height at which performance decreases regardless of surfacing depth. Other surfaces demonstrate a linear relationship between fall height and surface depth. Preliminary data tables showing the relative performance of surface depth to specific fall height ranges were developed for each surface material. From these preliminary data tables, recommendation tables were created as a cost-efficient alternative to using an impact testing device.

Continue reading Nick Pirone »

Characterizing Anterior Knee Mechanics through
Patellofemoral Joint Modeling

Patellofemoral pain affects nearly 25% of the general population, and is particularly prevalent in athletes and military personnel. It remains unclear as to why some people experience patellofemoral pain and others do not, however joint mechanics certainly play an integral role in pain development and disease progression. The mechanics of the patellofemoral joint are driven by multiple factors such as kinematics (the way people move and walk), morphology (the person-specific shape of the musculoskeletal tissues), and the loads that act about the surrounding area of the joint (muscle forces and activation patterns). Broadly, the aim of the research is to develop a computational tool that will help to investigate the contributions of these factors to anterior knee mechanics and thus joint pain longer term. A musculoskeletal model of the patellofemoral joint will be developed in OpenSim – an open source musculoskeletal modeling software – based on the OpenKnee data set, which is freely available. First, segmented MRI scans are used to generate the following geometries: the distal femur, distal femoral cartilage, the patella, patellar cartilage, the proximal tibia, and tendon and ligament insertion/attachment sites. These geometries are then smoothed and refined and imported into OpenSim, an open source musculoskeletal modeling software, with cartilage as contact geometries. Femoral and tibial kinematics will be defined along with knee extensor muscle forces, thus enabling the simulation of patellofemoral joint contact. Long term goals include studying the effects of different loading cases, different patellofemoral joint morphologies, and different kinematics on joint contact pressure.

Continue reading Kyle Young »

With Regards From Eagles and Condors: The U.S. Assistance of Operation Condor

Ranging from plenty of geographical backgrounds, the U.S. secret invasion of countries has been subject to heavy investigation and documentation. In particular, they’ve traditionally focused on countries that were having an increase in socialist policies. While civilians of these countries have often known of some level of foreign involvement in assassinations, coup d’états, and wildly inaccurate propaganda, that information has been largely drip fed to the public and scholars under the guise of national security. In fact, covert operations in Latin America have largely relied on first hand accounts until significant push is made for the Central Intelligence Agency and other government departments have had orders to publish documents. Specifically in the case of Operation Condor, documents in the last five years have made an extraordinary effort in piecing together a secretive and elusive part of history. Documents ranged from propaganda tactics to named targets of torture and assassination. Scholars coordinate between primary documents published across the major Condor operating countries alongside documents released by the CIA, FBI, the Department of the Interior, and others to paint a picture of what really happened during those years. I looked to investigate a series of primary documents released in 2019 in conjunction with research into covert operations during the earlier years of the Cold War in order to construct a more cohesive account of how involved the U.S. was into Operation Condor, and exactly what steps were taken to make sure that Operation Condor was as successful as possible.

Continue reading Peter Cholnoky »

Electroformed Heat Pipe Heat Exchanger
As the necessity to shift towards renewable forms of energy becomes ever more apparent in the wake of the consequences of climate change, one major barrier that has largely yet to be solved is the problem of energy storage. It is technologically possible to meet our energy demands solely with renewables, and likely many times over. However, when energy is generated is a critical factor to meet our necessary load demands each day and when most renewables are active is not controllable. Many different forms of energy storage already exist but with many issues such as cost, scaling, and environmental impact. We are exploring the development of low-cost energy storage mediums, such as salt, sand, or dirt. However, these mediums have very low thermal conductivity and thus it becomes necessary to synthesize different techniques to accomplish a feasible storage method. Principally, we are investigating the combination of a heat pipe and the topology of a bio-inspired heat exchanger. The highly complex geometries under consideration would possess a high surface area to volume ratio, facilitating conduction in low-conductivity media, but must be fabricated with non-traditional techniques such as electroforming. If we are able to successfully incorporate both of these elements into a thermal energy storage, it would lead to the cheap and economical storage of energy allowing us to justify larger scale use of renewable energy within our power grid.

Continue reading Colton Jiorle »

Evaluating Dutch Acceptance
The Netherlands has a legacy of tolerance. This tolerance earned the small, lowland provinces economic and social advantages over ideologically and religiously-torn larger powers. But since the Eighty Years’ War concluded with Dutch independence, tolerance has become less exclusive. The United States has heralded tolerance as a new global status quo and a base value of a modern liberal democracy. But, the rise of populism in the Netherlands as a response to unprecedented social change in the early twenty-first century has casted doubt onto the virtue of tolerance in the Western world today. Many accept that to ‘live and let live’ is no longer enough to counter intolerance and now seek a culture of acceptance. Multiculturalism, a product of tolerance, has been disowned in favor of integration, a product of acceptance, following political murders and the subsequent rise of populism. But in the Netherlands, the divide between tolerance and acceptance is often blurred, leading to vague social objectives. This paper will distinguish between acceptance and tolerance and demonstrate that the latter is unsatisfactory in stemming the populist rise that the Netherlands faces. This paper will review Dutch progress on social acceptance from the perspective of both native and recent immigrant groups in the Netherlands. This will be accomplished using survey data on beliefs regarding integration. Using these opinions and recent historical trends, this paper will determine if the Netherlands is still leading the world in progressiveness.

Continue reading Harrison Quinn »

Size Variation and Morphometric Analysis of Freshwater Mussels (Elliptio complanata) in the Susquehanna River

Freshwater mussels are a vastly understudied group of animals, and as a result, basic life history characteristics are unknown for many species. In some species, gravid females display a deceptive lure made from part of their mantle, but unless the female is displaying the lure, it is difficult to quickly and accurately determine the sex of mussels based on their external morphology. As a result, local mussel populations have hidden sex ratios, making estimates of population growth difficult. Using live Eastern elliptio mussels (Elliptio complanata) from the Susquehanna River and the Buffalo Creek, we sought to determine if there is a predictive relationship between sex and shape. Samples of gonadal fluid were extracted from the visceral mass to determine the sex of each individual. These data were then connected to three measurements of the corresponding shell: length, width, and depth (girth). No sexual dimorphism was present using these simple measurements. However, in a subset of the population sampled, further morphometric analyses of shape from digitized photographs of the animals revealed differences between the sexes, displaying a level of dimorphism previously unknown in this species. Determining the sex of live individuals has important implications for future studies of mussel biology, including answering questions related to mussel reproduction, demography, and population distribution.

Continue reading Isabelle Levesque-Du Bose »

Characterizing Noise in the Search for the Axion
Axions are theoretical new particles that may help solve large unanswered questions in physics ranging from the nature of dark matter to the Strong-CP problem. The Global Network of Optical Magnetometers (GNOME) is a collaboration searching for evidence of Axion and Axion-like particles by searching for the predicted interaction between the new particles and atomic spins. Magnetometers are highly sensitive instruments traditionally used to measure the magnetic field’s effect on atomic spins, but after drastically reducing the local magnetic field they become an ideal tool to detect the effects of the Axion. We are contributing data from a magnetometer in Lewisburg, and are examining noise characteristics of the data across time and frequency. Gaussianity is one such characteristic, which when estimated can help us to better understand the significance of possible detections and nondetections. We developed a tool to quantify this parameter for GNOME’s magnetometers.

Continue reading Ephraim Oliphant »