Sunset Piracy: The Ends of Atlantic Piratical Careers in the Age of Sail

This thesis concerns the careers of pirates in the latest stage of that career, as pirates prepared to end their roving of the seas in order to “settle down.” Though pirates are idolized in modern fiction, their ends are often overshadowed by the highlights of their careers. Here, the goal is to find what motivated pirates to engage in a life as outlaws and then at some point choose to cast that life aside. Conclusions on this are drawn from both primary and secondary sources where pirates gave information pertaining to their view of the world and retirement in it, often without realizing it. The thesis explores the interactions pirates had with the governments acting within the Atlantic world and the natives who inhabited it. Lastly, the thesis concludes that sea rovers gained a great deal through piracy, yet to retire they surrendered at least some of what they gained. Of interest, then, is what was lost through what methods of retirement, and what was retained through others

A Self Assembled Nanoelectronic Quantum Computer Based on the Rashba Effect in Quantum Dots

Quantum computers promise vastly enhanced computational power and an uncanny ability to solve classically intractable problems. However, few proposals exist for robust, solid state implementation of such computers where the quantum gates are sufficiently miniaturized to have nanometer-scale dimensions. Here I present a new approach whereby a complete computer with nanoscale gates might be self-assembled using chemical synthesis. Specifically, I demonstrate how to self-assemble the fundamental unit of this quantum computer - a 2-qubit universal quantum controlled-NOT gate - based on two exchange coupled multilayered quantum dots. Then I show how these gates can be wired using thiolated conjugated molecules as electrical connectors. A qubit is encoded in the ground state of a quantum dot spin-split by the Rashba interaction. Arbitrary qubit rotations are effected by bringing the spin splitting energy in a target quantum dot in resonance with a global ac magnetic field by applying a potential pulse of appropriate amplitude and duration to the dot. The controlled dynamics of the 2-qubit controlled-NOT operation (XOR) can be realized by exploiting the exchange coupling with the nearest neighboring dot. A complete prescription for initialization of the computer and data input/output operations is presented.Comment: 22 pages, 4 figure

Cone beam neutron interferometry: from modeling to applications

Phase-grating moire interferometers (PGMIs) have emerged as promising candidates for the next generation of neutron interferometry, enabling the use of a polychromatic beam and manifesting interference patterns that can be directly imaged by existing neutron cameras. However, the modeling of the various PGMI configurations is limited to cumbersome numerical calculations and backward propagation models which often do not enable one to explore the setup parameters. Here we generalize the Fresnel scaling theorem to introduce a k-space model for PGMI setups illuminated by a cone beam, thus enabling an intuitive forward propagation model for a wide range of parameters. The interference manifested by a PGMI is shown to be a special case of the Talbot effect, and the optimal fringe visibility is shown to occur at the moire location of the Talbot distances. We derive analytical expressions for the contrast and the propagating intensity profiles in various conditions, and analyze the behaviour of the dark-field imaging signal when considering sample characterization. The model's predictions are compared to experimental measurements and good agreement is found between them. Lastly, we propose and experimentally verify a method to recover contrast at typically inaccessible PGMI autocorrelation lengths. The presented work provides a toolbox for analyzing and understanding existing PGMI setups and their future applications, for example extensions to two-dimensional PGMIs and characterization of samples with non-trivial structures

Quantum Correlations in NMR systems

In conventional NMR experiments, the Zeeman energy gaps of the nuclear spin ensembles are much lower than their thermal energies, and accordingly exhibit tiny polarizations. Generally such low-purity quantum states are devoid of quantum entanglement. However, there exist certain nonclassical correlations which can be observed even in such systems. In this chapter, we discuss three such quantum correlations, namely, quantum contextuality, Leggett-Garg temporal correlations, and quantum discord. In each case, we provide a brief theoretical background and then describe some results from NMR experiments.Comment: 21 pages, 7 figure

Mismatches in scale between highly mobile marine megafauna and marine protected areas

Marine protected areas (MPAs), particularly large MPAs, are increasing in number and size around the globe in part to facilitate the conservation of marine megafauna under the assumption that large-scale MPAs better align with vagile life histories; however, this alignment is not well established. Using a global tracking dataset from 36 species across five taxa, chosen to reflect the span of home range size in highly mobile marine megafauna, we show most MPAs are too small to encompass complete home ranges of most species. Based on size alone, 40% of existing MPAs could encompass the home ranges of the smallest ranged species, while only < 1% of existing MPAs could encompass those of the largest ranged species. Further, where home ranges and MPAs overlapped in real geographic space, MPAs encompassed < 5% of core areas used by all species. Despite most home ranges of mobile marine megafauna being much larger than existing MPAs, we demonstrate how benefits from MPAs are still likely to accrue by targeting seasonal aggregations and critical life history stages and through other management techniques.Fil: Conners, Melinda G.. University of Washington; Estados Unidos. State University of New York. Stony Brook University; Estados UnidosFil: Sisson, Nicholas B.. Old Dominion University; Estados UnidosFil: Agamboue, Pierre D.. Wildlife Conservation Society; GabónFil: Atkinson, Philip W.. British Trust For Ornithology; Reino UnidoFil: Baylis, Alastair M. M.. Macquarie University; Australia. South Atlantic Environmental Research Institute; Reino UnidoFil: Benson, Scott R.. Noaa National Marine Fisheries Service Southwest Regional Office; Estados Unidos. Moss Landing Marine Laboratories; Estados UnidosFil: Block, Barbara A.. University of Stanford; Estados UnidosFil: Bograd, Steven J.. Noaa National Marine Fisheries Service Southwest Regional Office; Estados UnidosFil: Bordino, Pablo. Mote Marine Laboratory; Estados UnidosFil: Bowen, W.D.. Bedford Institute Of Oceanography, Fisheries And Oceans Canada; Canadá. Dalhousie University Halifax; CanadáFil: Brickle, Paul. South Atlantic Environmental Research Institute; Reino Unido. University of Aberdeen; Reino Unido. University Of Aberdeeen; Reino UnidoFil: Bruno, Ignacio Matias. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: González Carman, Victoria. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Champagne, Cory D.. University of Washington; Estados UnidosFil: Crocker, Daniel E.. Sonoma State University; Estados UnidosFil: Costa, Daniel P.. University of California; Estados UnidosFil: Dawson, Tiffany M.. University Of Central Florida; Estados Unidos. Old Dominion University; Estados UnidosFil: Deguchi, Tomohiro. Yamashina Institute For Ornithology; JapónFil: Dewar, Heidi. Noaa National Marine Fisheries Service Southwest Regional Office; Estados UnidosFil: Doherty, Philip D.. University of Exeter; Reino UnidoFil: Eguchi, Tomo. Noaa National Marine Fisheries Service Southwest Regional Office; Estados UnidosFil: Formia, Angela. Wildlife Conservation Society; Gabón. African Aquatic Conservation Fund; Estados UnidosFil: Godley, Brendan J.. University of Exeter; Reino UnidoFil: Graham, Rachel T.. Maralliance; PanamáFil: Gredzens, Christian. Padre Island National Seashore; Estados UnidosFil: Hart, Kristen M.. United States Geological Survey; Estados UnidosFil: Hawkes, Lucy A.. University of Exeter; Reino UnidoFil: Henderson, Suzanne. Scottish Natural Heritage; Reino UnidoFil: Henry, Robert William. Groundswell Coastal Ecology; Estados UnidosFil: Hückstädt, Luis A.. University of Exeter; Reino Unido. University of California; Estados Unido

Mouse Ribosomal RNA Genes Contain Multiple Differentially Regulated Variants

Previous cytogenetic studies suggest that various rDNA chromosomal loci are not equally active in different cell types. Consistent with this variability, rDNA polymorphism is well documented in human and mouse. However, attempts to identify molecularly rDNA variant types, which are regulated individually (i.e., independent of other rDNA variants) and tissue-specifically, have not been successful. We report here the molecular cloning and characterization of seven mouse rDNA variants (v-rDNA). The identification of these v-rDNAs was based on restriction fragment length polymorphisms (RFLPs), which are conserved among individuals and mouse strains. The total copy number of the identified variants is less than 100 and the copy number of each individual variant ranges from 4 to 15. Sequence analysis of the cloned v-rDNA identified variant-specific single nucleotide polymorphisms (SNPs) in the transcribed region. These SNPs were used to develop a set of variant-specific PCR assays, which permitted analysis of the v-rDNAs' expression profiles in various tissues. These profiles show that three v-rDNAs are expressed in all tissues (constitutively active), two are expressed in some tissues (selectively active), and two are not expressed (silent). These expression profiles were observed in six individuals from three mouse strains, suggesting the pattern is not randomly determined. Thus, the mouse rDNA array likely consists of genetically distinct variants, and some are regulated tissue-specifically. Our results provide the first molecular evidence for cell-type-specific regulation of a subset of rDNA

A Multi-Component Model of the Developing Retinocollicular Pathway Incorporating Axonal and Synaptic Growth

During development, neurons extend axons to different brain areas and produce stereotypical patterns of connections. The mechanisms underlying this process have been intensively studied in the visual system, where retinal neurons form retinotopic maps in the thalamus and superior colliculus. The mechanisms active in map formation include molecular guidance cues, trophic factor release, spontaneous neural activity, spike-timing dependent plasticity (STDP), synapse creation and retraction, and axon growth, branching and retraction. To investigate how these mechanisms interact, a multi-component model of the developing retinocollicular pathway was produced based on phenomenological approximations of each of these mechanisms. Core assumptions of the model were that the probabilities of axonal branching and synaptic growth are highest where the combined influences of chemoaffinity and trophic factor cues are highest, and that activity-dependent release of trophic factors acts to stabilize synapses. Based on these behaviors, model axons produced morphologically realistic growth patterns and projected to retinotopically correct locations in the colliculus. Findings of the model include that STDP, gradient detection by axonal growth cones and lateral connectivity among collicular neurons were not necessary for refinement, and that the instructive cues for axonal growth appear to be mediated first by molecular guidance and then by neural activity. Although complex, the model appears to be insensitive to variations in how the component developmental mechanisms are implemented. Activity, molecular guidance and the growth and retraction of axons and synapses are common features of neural development, and the findings of this study may have relevance beyond organization in the retinocollicular pathway