1,148 research outputs found

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    The Flexibility of Thomistic Metaphysical Principles: Byzantine Thomists, Personalist Thomists, and Jacques Maritain

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    Thomistic metaphysics has been challenged on the grounds that its principles are inconsistent with our experiences of divine action and of our own subjectivity. Challenges of this sort have been raised by Eastern Christian thinkers in the school of Gregory Palamas and by contemporary Personalists; they propose alternative metaphysics to explain these experiences. Against these objections and against those Thomists who hold that Thomas Aquinas’ claims exclude Byzantine and Personalist metaphysics, I argue that Thomas’ metaphysical principles already have “flexibility” built into them, such that they can accommodate ways that reality is given in experience, which Thomas did not consider. I argue for this claim using the work of Byzantine and Personalist Thomists, and especially of Jacques Maritain, who outlines several ways in which Thomistic metaphysical principles can be expanded to explain experiences that he did not consider

    Cold atom confinement in an all-optical dark ring trap

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    We demonstrate confinement of 85^{85}Rb atoms in a dark, toroidal optical trap. We use a spatial light modulator to convert a single blue-detuned Gaussian laser beam to a superposition of Laguerre-Gaussian modes that forms a ring-shaped intensity null bounded harmonically in all directions. We measure a 1/e spin-relaxation lifetime of ~1.5 seconds for a trap detuning of 4.0 nm. For smaller detunings, a time-dependent relaxation rate is observed. We use these relaxation rate measurements and imaging diagnostics to optimize trap alignment in a programmable manner with the modulator. The results are compared with numerical simulations.Comment: 5 pages, 4 figure

    Instability of the Microemulsion Channel in Block Copolymer-Homopolymer Blends

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    Field theoretic simulations are used to predict the equilibrium phase diagram of symmetric blends of AB diblock copolymer with A- and B-type homopolymers. Experiments generally observe a channel of bicontinuous microemulsion (BμE) separating the ordered lamellar (LAM) phase from coexisting homopolymer-rich (A+B) phases. However, our simulations find that the channel is unstable with respect to macrophase separation, in particular, A+B+BμE coexistence at high T and A+B+LAM coexistence at low T. The preference for three-phase coexistence is attributed to a weak attractive interaction between diblock monolayers

    Magnetically-controlled velocity selection in a cold atom sample using stimulated Raman transitions

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    We observe velocity-selective two-photon resonances in a cold atom cloud in the presence of a magnetic field. We use these resonances to demonstrate a simple magnetometer with sub-mG resolution. The technique is particularly useful for zeroing the magnetic field and does not require any additional laser frequencies than are already used for standard magneto-optical traps. We verify the effects using Faraday rotation spectroscopy.Comment: 5 pages, 6 figure

    From the track to the ocean : using flow control to improve marine bio-logging tags for cetaceans

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    This project was funded by the National Oceanographic Partnership Program [National Science Foundation via the Office of Naval Research N00014-11-1-0113]. C. Spencer Garborg was supported by a Grove City College Swezey Student Fellowship to Erik Anderson. Mark Johnson was funded by a Marie Curie-Sklodowska grant from the European Union. All supplemental data files are available from the Dryad Digital Repository (doi:10.5061/dryad.4j4m1).Bio-logging tags are an important tool for the study of cetaceans, but superficial tags inevitably increase hydrodynamic loading. Substantial forces can be generated by tags on fast-swimming animals, potentially affecting behavior and energetics or promoting early tag removal. Streamlined forms have been used to reduce loading, but these designs can accelerate flow over the top of the tag. This non-axisymmetric flow results in large lift forces (normal to the animal) that become the dominant force component at high speeds. In order to reduce lift and minimize total hydrodynamic loading this work presents a new tag design (Model A) that incorporates a hydrodynamic body, a channel to reduce fluid speed differences above and below the housing and wing to redirect flow to counter lift. Additionally, three derivatives of the Model A design were used to examine the contribution of individual flow control features to overall performance. Hydrodynamic loadings of four models were compared using computational fluid dynamics (CFD). The Model A design eliminated all lift force and generated up to ~30 N of downward force in simulated 6 m/s aligned flow. The simulations were validated using particle image velocimetry (PIV) to experimentally characterize the flow around the tag design. The results of these experiments confirm the trends predicted by the simulations and demonstrate the potential benefit of flow control elements for the reduction of tag induced forces on the animal.Publisher PDFPeer reviewe

    Acculturation-Related Factors of Dietary Pattern Changes among Indigenous Adolescents in Mt. Arayat, Philippines

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    This study aimed to determine the levels of dietary acculturation and factors affecting acculturationrelated changes in dietary patterns of 15 adolescents in an indigenous community in Mt. Arayat, Central Luzon, Philippines displaced after the eruption of Mt. Pinatubo in 1991. Mixed-methods sequential explanatory design (using modified scales) was employed to measure dietary acculturation; index analyses to evaluate dietary patterns; and focus group discussion to determine factors leading to dietary acculturation. Majority was found to be bicultural (93.33%) and the mean dietary pattern index score was 69.40 implying a need for dietary improvement. Moderate to high levels of dietary acculturation were observed on the traditional food block, while low to moderate levels were observed towards the dominant food block. Various psychosocial factors driving dietary choices cumulatively affect dietary patterns of adolescents experiencing acculturation in this study, including but not limited to: 1) the neighboring communities’ ethnocultural composition facilitates acculturation primarily through language fluency; 2) prevalence of discrimination exerts an external pressure to adopt host culture for social acceptance; 3) economic need for integration to sustain day-to-day activities exists; 4) religious feasts and gatherings centered on foods previously unknown to them have been introduced; 5) food selection behavior shifts due to acquired experiences of food whether sensory or cognitive; and 6) their attitudes towards assimilation majorly characterizes the gradual internalization of host culture
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