Welcome to Allegheny Collegeโs DSpace repository. Our institutional repository is rich with Allegheny history and important documents, including
- The Documents of Ida M. Tarbell, a digitized collection of papers from the groundbreaking journalist, author, and lecturer
- Civil War letters of Pvt. Willard A. Cutter and Stephen R. Clark
- The Campus student newspaper and The Kaldron student yearbooks.
- Senior Projects (currently available to Allegheny community only)
- Course Syllabi (currently available to Allegheny community only)
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Recent Submissions
Item Ornamentation and body condition, but not glucocorticoids, predict wild songbird cloacal microbiome community and diversity(Wiley, 2024-12-03)Animal populations can exhibit dramatic variation in individual fitness, and microbiota are emerging as a potentially understudied factor influencing host health. Bacterial diversity and community structure of the gut microbiome are associated with many aspects of fitness in animals, but relatively little is known about the generality of these relationships in wild populations and non-mammalian taxa. We studied the northern cardinal Cardinalis cardinalis, a member of a taxon that is ecologically important but underrepresented in microbiome research: songbirds. To test for relationships between the microbiota and host fitness, we sampled the cloacal microbiomes of wild cardinals and measured body condition index, assessed coloration of sexual ornaments (beak and plumage), and collected blood to estimate the glucocorticoid response to stress. Both alpha and beta bacterial diversity were related to individual variation in body condition and several sexual ornaments, but not glucocorticoid concentrations. Our results from a free-living songbird population add to a growing body of research linking avian host fitness to internal bacterial community characteristics. This study sets the stage for manipulative experiments to determine how challenges to fitness and microbiomes may upset these relationships.Item Outcomes of Sub-Neptune Collisions(IOP Publishing Ltd, 2024-12-01)Observed high multiplicity planetary systems are often tightly packed. Numerical studies indicate that such systems are susceptible to dynamical instabilities. Dynamical instabilities in close-in tightly packed systems, similar to those found in abundance by Kepler, often lead to planet-planet collisions. For sub-Neptunes, the dominant type of observed exoplanets, the planetary mass is concentrated in a rocky core, but the volume is dominated by a low-density gaseous envelope. For these, using the traditional perfect merger assumption (also known as the 'sticky-sphere' approximation) to resolve collisions is questionable. Using both N-body integration and smoothed-particle hydrodynamics, we have simulated sub-Neptune collisions for a wide range in realistic kinematic properties such as impact parameters (๐) and impact velocities (๐ฃ) to study the possible outcomes in detail. We find that the majority of the collisions with kinematic properties similar to what is expected from dynamical instabilities in multiplanet systems may not lead to mergers of sub-Neptunes. Instead, both sub-Neptunes survive the encounter, often with significant atmosphere loss. When mergers do occur, they can involve significant mass loss and can sometimes lead to complete disruption of one or both planets. Sub-Neptunes merge or disrupt if ๐ < ๐๐สณโฑแต, a critical value dependent on ๐ฃ/๐ฃโโ๐, where ๐ฃโโ๐ is the escape velocity from the surface of the hypothetical merged planet assuming perfect merger. For ๐ฃ/๐ฃโโ๐ โฒ 2.5, ๐๐สณโฑแต โ (๐ฃ/๐ฃโโ๐)โปยฒ, and collisions with ๐ < ๐๐สณโฑแต typically lead to mergers. On the other hand, for ๐ฃ/๐ฃโโ๐ โณ 2.5, ๐๐สณโฑแต โ ๐ฃ/๐ฃโโ๐, and the collisions with ๐ < ๐๐สณโฑแต can result in complete destruction of one or both sub-Neptunes.Item 2024-11-01: The Campus(Allegheny College, 2024-11-01)Item 2024-10-25: The Campus(Allegheny College, 2024-10-24)Item 2024-10-04: The Campus(Allegheny College, 2024-10-04)
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