Collisions of vortex filament pairs

We consider the problem of collisions of vortex filaments for a model introduced by Klein, Majda and Damodaran, and Zakharov to describe the interaction of almost parallel vortex filaments in three-dimensional fluids. Since the results of Crow examples of collisions are searched as perturbations of antiparallel translating pairs of filaments, with initial perturbations related to the unstable mode of the linearized problem; most results are numerical calculations. In this article we first consider a related model for the evolution of pairs of filaments and we display another type of initial perturbation leading to collision in finite time. Moreover we give numerical evidence that it also leads to collision through the initial model. We finally study the self-similar solutions of the model

Cosmopolitan Goes Intercultural: A Semiotic Analysis of Cosmopolitan Magazine Covers

This project focused on an analysis of the messages portrayed through four covers of Cosmopolitan’s international magazines in November of 2015. This study investigated if and how Cosmopolitan creates a single, worldwide ideal image for women. Using Arthur Asa Berger’s method of semiotic analysis, the four covers were analyzed according to five categories: the model’s story or significance in the world today, the model’s race, clothing and other artifacts worn by the model, the model’s body language, and the words and phrases printed on the cover. This study uncovered three consistent, major themes: sex, fitness, and success in terms of wealth. The ideologies contained in these themes are spread across the countries in which Cosmopolitan distributes their magazine, giving women worldwide the idea that these are the expectations of their gender and that these values should be embraced. The study suggests that, if all themes represented in the covers portray and glorify U.S.-centric values, there is potential to override or devalue the cultural values of other countries in which the magazine is distributed. The paper upon which this poster is based was written for the Senior Seminar course in Communication Arts. The paper was competitively selected for presentation at the Northwest Communication Association Conference in April 2016

Nitrate-Dependent Iron Oxidation: A Potential Mars Metabolism

This work considers the hypothetical viability of microbial nitrate-dependent Fe2+ oxidation (NDFO) for supporting simple life in the context of the early Mars environment. This draws on knowledge built up over several decades of remote and in situ observation, as well as recent discoveries that have shaped current understanding of early Mars. Our current understanding is that certain early martian environments fulfill several of the key requirements for microbes with NDFO metabolism. First, abundant Fe2+ has been identified on Mars and provides evidence of an accessible electron donor; evidence of anoxia suggests that abiotic Fe2+ oxidation by molecular oxygen would not have interfered and competed with microbial iron metabolism in these environments. Second, nitrate, which can be used by some iron oxidizing microorganisms as an electron acceptor, has also been confirmed in modern aeolian and ancient sediment deposits on Mars. In addition to redox substrates, reservoirs of both organic and inorganic carbon are available for biosynthesis, and geochemical evidence suggests that lacustrine systems during the hydrologically active Noachian period (4.1–3.7 Ga) match the circumneutral pH requirements of nitrate-dependent iron-oxidizing microorganisms. As well as potentially acting as a primary producer in early martian lakes and fluvial systems, the light-independent nature of NDFO suggests that such microbes could have persisted in sub-surface aquifers long after the desiccation of the surface, provided that adequate carbon and nitrates sources were prevalent. Traces of NDFO microorganisms may be preserved in the rock record by biomineralization and cellular encrustation in zones of high Fe2+ concentrations. These processes could produce morphological biosignatures, preserve distinctive Fe-isotope variation patterns, and enhance preservation of biological organic compounds. Such biosignatures could be detectable by future missions to Mars with appropriate instrumentation

Physical and Monetary Input-Output Analysis: What Makes the Difference?

A recent paper in which embodied land appropriation of exports was calculated using a physical input-output model (Ecological Economics 44 (2003) 137-151) initiated a discussion in this journal concerning the conceptual differences between input-output models using a coefficient matrix based on physical input-output tables (PIOTs) in a single unit of mass and input-output models using a coefficient matrix based on monetary input-output tables (MIOTs) extended by a coefficient vector of physical factor inputs per unit of output. In this contribution we argue that the conceptual core of the discrepancies found when comparing outcomes obtained using physical vs. monetary input-output models lies in the assumption of prices and not in the treatment of waste as has been claimed (Ecological Economics 48 (2004) 9-17). We first show that a basic static input-output model with the coefficient matrix derived from a monetary input-output table is equivalent to one where the coefficient matrix is derived from an input-output table in physical units provided that the assumption of unique sectoral prices is satisfied. We then illustrate that the physical input-output table that was used in the original publication does not satisfy the assumption of homogenous sectoral prices, even after the inconsistent treatment of waste in the PIOT is corrected. We show that substantially different results from the physical and the monetary models in fact remain. Finally, we identify and discuss possible reasons for the observed differences in sectoral prices and draw conclusions for the future development of applied physical input-output analysis.

In vitro and in vivo validation of human and goat chondrocyte labeling by green fluorescent protein lentivirus transduction

We investigated whether human articular chondrocytes can be labeled efficiently and for long-term with a green fluorescent protein (GFP) lentivirus and whether the viral transduction would influence cell proliferation and tissue-forming capacity. The method was then applied to track goat articular chondrocytes after autologous implantation in cartilage defects. Expression of GFP in transduced chondrocytes was detected cytofluorimetrically and immunohistochemically. Chondrogenic capacity of chondrocytes was assessed by Safranin-O staining, immunostaining for type II collagen, and glycosaminoglycan content. Human articular chondrocytes were efficiently transduced with GFP lentivirus (73.4 +/- 0.5% at passage 1) and maintained the expression of GFP up to 22 weeks of in vitro culture after transduction. Upon implantation in nude mice, 12 weeks after transduction, the percentage of labeled cells (73.6 +/- 3.3%) was similar to the initial one. Importantly, viral transduction of chondrocytes did not affect the cell proliferation rate, chondrogenic differentiation, or tissue-forming capacity, either in vitro or in vivo. Goat articular chondrocytes were also efficiently transduced with GFP lentivirus (78.3 +/- 3.2%) and maintained the expression of GFP in the reparative tissue after orthotopic implantation. This study demonstrates the feasibility of efficient and relatively long-term labeling of human chondrocytes for co-culture on integration studies, and indicates the potential of this stable labeling technique for tracking animal chondrocytes for in cartilage repair studies