Showing 161 - 170 of 564 Items

Sensitivity Analysis of Basins of Attraction for Gradient-Based Optimization Methods

Date: 2022-01-01

Creator: Gillian King

Access: Open access

This project is an analysis of the effectiveness of five distinct optimization methods in their ability in producing clear images of the basins of attraction, which is the set of initial points that approach the same minimum for a given function. Basin images are similar to contour plots, except that they depict the distinct regions of points--in unique colors--that approach the same minimum. Though distinct in goal, contour plots are useful to basin research in that idealized basin images can be inferred from the steepness levels and location of extrema they depict. Effectiveness of the method changes slightly depending on the function, but is generally defined as how closely the basin image models contour information on where the true minima are located, and by the clarity of the resulting image in depicting well-defined regions. The methods are tested on four distinct functions which were chosen to assess how each method performs in the presence of various challenges. This project ranks the five methods for their overall effectiveness and consistency across the four functions, and also analyzes the sensitivity of the methods when small changes are made to the function. In general, less sensitive and consistently effective methods are more applicable and reliable in applied optimization research.


Miniature of Theories of Thanks: Affect Studies, Reciprocity, and Theoretical Perspectives on Gratitude
Theories of Thanks: Affect Studies, Reciprocity, and Theoretical Perspectives on Gratitude
This record is embargoed.
    • Embargo End Date: 2027-05-19

    Date: 2022-01-01

    Creator: Clayton James Wackerman

    Access: Embargoed



      Site, Power, and Experience: Three Contemporary Installation Works on Global Mobility

      Date: 2021-01-01

      Creator: Xiyin Sabrina Lin

      Access: Open access

      This Honors Project investigates the themes of immigration, space, and mobility through the lens of contemporary installation art. It addresses a brief history of global contemporary art, arguing that art of the past two decades has been shaped by preoccupations with and tensions surrounding space. Using the works of Yanagi Yukinori, Alfredo Jaar, and Doris Salcedo as case studies, the essay analyzes how artists use the medium of installation to address institutional history, contemporary geopolitics, as well as individual and collective experience. It interrogates the different aspects of installation art, including temporality, site-specificity, and the use of language, to demonstrate how the medium allows artists to use their own position in the system to critique its inherent limitations.


      Assigning Legal Punishment: Individual Differences in Justice Sensitivity and Selective Attention

      Date: 2015-05-01

      Creator: Emily C. Weinberger

      Access: Open access

      Selective attention and justice sensitivity (JS), a personality trait reflecting individual differences in perceptions of injustice, have been shown to affect how people assign punishments. In the present study peoples’ decision-making processes were investigated to better understand the inconsistencies in legal punishment decisions, particularly when using retributive versus restorative justice. Subjects participated in three phases of the experiment. First, subjects completed a justice sensitivity scale and then rated the appropriateness of punishment options to handle a criminal scenario. Second, participants’ selective attention was indicated by their recall of pertinent features from three ambiguous criminal scenarios. Finally, participants were primed with either restorative justice or neutral control words, and rated the appropriateness of punishment options to handle a new criminal scenario. Results revealed no significant associations between JS and ratings of punishment options, although patterns suggested negative relationships between observer JS and retributive justice ratings, and victim JS and restorative justice ratings. Results did show a significant effect of JS in predicting the facts remembered, such that as observer JS increased, more restorative justice facts were recalled, and as victim JS increased, fewer restorative justice facts were recalled. No significant effect of the restorative justice prime was observed. These results may contribute to better understanding of criminal justice policy in the United States.


      The Structure and Unitary Representations of SU(2,1)

      Date: 2015-05-01

      Creator: Andrew J Pryhuber

      Access: Open access



      Antimicrobial Peptides (AMPs) in the Lobster, Homarus Americanus: Isolation and Activity

      Date: 2021-01-01

      Creator: Ruby Chimereucheya Ahaiwe

      Access: Open access

      The American lobster Homarus americanus uses its innate immune system for protection against foreign bodies and diseases. Hemocytes in the innate immune system are responsible for the rapid and effective cellular response against pathogens and infections observed in lobsters. These hemocytes, particularly semi-granulocytes and granulocytes, store antimicrobial peptides (AMPs) which specifically target and destroy microbes. Hemocyte samples from the American lobster Homarus americanus hemolymph or circulatory fluid, mixed and fractionated into separated semi-granular and granular cell samples, were analyzed for possible AMP presence. A defensin AMP, Hoa-D1, (SYVRSCSSNGGDCVYRCYGNIINGACSGSRVCCRSGGGYamide; with C representing a cysteine participating in a disulfide bond) was successfully isolated and identified by mass using reversed-phase high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS/MS). Preliminary results also show the defensin AMP to be concentrated in the semi-granulocytes and granulocytes.Hoa-D1 was isolated via HPLC fractionation. Isolated Hoa-D1 and semi-granular and granular hemocyte extracts were tested for bioactivity against the gram-negative bacteria, Escherichia coli, using the Kirby-Bauer disk diffusion assay. The assay did not show any activity, an outcome attributed to concentrations of the AMP that were too low to have any antimicrobial effect on E. coli. Subsequent work on this study should involve increasing the concentration of Hoa-D1 in test samples. Studying function of AMPs in the American lobster can provide more information on the depth of their cellular immune responses in other crustaceans, and possibly contribute to the development of novel antibiotics for treating diseases in humans.


      Modeling UV Light Through N95 Filters

      Date: 2023-01-01

      Creator: Lorenzo Hess

      Access: Open access

      Reuse of N95 FFRs helps mitigate the effects of shortages. UV-C exposure is an ideal method for the decontamination necessary for FFR reuse. Recent research quantifies the transmittance of UV-C through the 3M1870+ and 3M9210+ FFRs [1]. Other research measures the reduction in viral load in relation to UV-C exposure time [11]. We design and program a ray tracing simulator in MATLAB to characterize the distribution of scattered photons in N95 FFRs. We implement an object-oriented FFR with configurable physical characteristics. We use the simulator to record the number of photons available for decontamination in each sub-layer of the filtering layers of the 3M1870+ and 3M9210+ for a given number of photons incident to the layers. We make assumptions about the photon absorption and viral deactivation in each sub-layer to derive a relation between the number of incident photons and the number of viruses remaining. The transmittance computed by our simulator matches the experimentally measured transmittance. The diameter of the simulated scattered beam also matches the experimentally measured scattered beam diameters. Our data, combined with our assumptions about absorption and deactivation, however, fail to account for the dropoff in viral load observed at about 25 seconds of exposure time in the 3M1870+.


      Miniature of Identification and characterization of genes involved in <i>Helicobacter pylori</i> lipopolysaccharide and glycoprotein biosynthesis
      Identification and characterization of genes involved in Helicobacter pylori lipopolysaccharide and glycoprotein biosynthesis
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          Date: 2021-01-01

          Creator: Andrew James Mulholland

          Access: Access restricted to the Bowdoin Community



            Determining the sites at which neuromodulators exert peripheral effects in the cardiac neuromuscular system of the American Lobster, Homarus americanus

            Date: 2021-01-01

            Creator: Audrey Elizabeth Jordan

            Access: Open access

            Networks of neurons known as central pattern generators (CPGs) generate rhythmic patterns of output to drive behaviors like locomotion. CPGs are relatively fixed networks that produce consistent patterns in the absence of other inputs. The heart contractions of the Homarus americanus are neurogenic and controlled by the CPG known as the cardiac ganglion. Neuromodulators can enable flexibility in CPG motor output, and also on muscle contractions by acting on the neuromuscular junction and the muscle itself. A tissue-specific transcriptome gleaned from the cardiac ganglion and cardiac muscle of the American lobster was used to predict the sites and sources of a variety of crustacean neuromodulators. If corresponding receptors were predicted to be expressed in the cardiac muscle, then it was hypothesized that the neuropeptide had peripheral effects. One peptide for which a cardiac muscle receptor was identified is myosuppressin. Myosuppressin has been shown to have modulatory effects at the cardiac neuromuscular system of the American lobster. In previous research, myosuppressin had modulatory effects on the periphery of cardiac neuromuscular system alone. It remains an open question of whether myosuppressin acts on the cardiac muscle directly, if it is exerting its effects at the neuromuscular junction (NMJ), or both. To test this, I performed physiological experiments on the isolated NMJ. Myosuppressin did not modulate the amplitude of the excitatory junction potentials. Since no modulatory effects were seen at the NMJ, the cardiac muscle was isolated from the cardiac ganglion and then glutamate-evoked contractions were stimulated. I showed that myosuppressin increased glutamate-evoked contraction amplitude. These data suggest myosuppressin exerts its peripheral effects at the cardiac muscle and not the NMJ.


            Miniature of “One of Folly’s Failures”: <i>Plessy v. Ferguson</i> (1896) and the Decline of the Thirteenth Amendment
            “One of Folly’s Failures”: Plessy v. Ferguson (1896) and the Decline of the Thirteenth Amendment
            This record is embargoed.
              • Embargo End Date: 2025-05-14

              Date: 2020-01-01

              Creator: Grace Ann Fenwick

              Access: Embargoed