The Oseen-Navier-Stokes flow in the exterior of a rotating obstacle: The non-autonomous case

Consider the Navier-Stokes flow past a rotating obstacle with a general time-dependent angular velocity and a time-dependent outflow condition at infinity -- sometimes called an Oseen condition. By a suitable change of coordinates the problem is transformed to an non-autonomous problem with unbounded drift terms on a fixed exterior domain $\Omega\subset \R^d$. It is shown that the solution to the linearized problem is governed by a strongly continuous evolution system $\{T_\Omega(t,s)\}_{t\geq s\geq0}$ on $L^p_\sigma(\Omega)$ for $1<p<\infty$. Moreover, $L^p$-$L^q$ smoothing properties and gradient estimates of $T_\Omega(t,s)$, $0\leq s \leq t$, are obtained. These results are the key ingredients to show local in time existence of mild solutions to the full nonlinear problem for $p\geq d$ and initial value in $L^p_\sigma(\Omega)$.Comment: 25 page

Reasoning, Science, and the Ghost Hunt

This paper details how ghost hunting, as a set of learning activities, can be used to enhance critical thinking and philosophy of science classes. We describe in some detail our own work with ghost hunting, and reflect on both intended and unintended consequences of this pedagogical choice. This choice was partly motivated by students’ lack of familiarity with science and philosophic questions about it. We offer reflections on our three different implementations of the ghost hunting activities. In addition, we discuss the practical nuances of implementing these activities, as well the relation of ghost hunting to our course content, including informal fallacies and some models for scientific inference. We conclude that employing ghost hunting along-side traditional activities and content of critical thinking and philosophy of science offers a number of benefits, including being fun, increasing student attendance, enhancing student learning, and providing a platform for campus wide dialogues about philosophy

All That Sprawl, Y’all: An Analysis of Development on Steinwehr Avenue and York Street in Gettysburg, Pennsylvania, from 1971 to 2014

The advent of the automobile transformed the American landscape in the 20th century. In conjunction with the increasing importance of the automobile, numerous post-WW II government programs such as the Interstate Highway System encouraged suburban sprawl. Towns and cities adjacent to tourist attractions, known as gateway communities, face unique problems caused by sprawl. Gettysburg, Pennsylvania, is an example of a gateway community as it includes the Gettysburg National Military Park. Two study sites, portions of Steinwehr Avenue and York Street, were studied to analyze the effects of sprawl in Gettysburg. The sites were analyzed using ArcGIS, data compiled from historic phonebooks, and discussions with local business owners. Development along York Street exemplifies an auto-centric culture with many regional and national chain establishments set back from the road. Steinwehr Avenue represents a walkable community comprising on-street parking, sidewalks, and local “mom-and-pop” establishments. Trends associated with categories of businesses varied between the two sites and revealed different development patterns. We predict that that York Street will continue to sprawl while Steinwehr Avenue development will be limited due to its close proximity to the battlefield

Hansel and Gretel

Thesis (M.A.)--Boston Universit

Heterotrophic bacteria exhibit a wide range of rates of extracellular production and decay of hydrogen peroxide

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bond, R. J., Hansel, C. M., & Voelker, B. M. Heterotrophic bacteria exhibit a wide range of rates of extracellular production and decay of hydrogen peroxide. Frontiers in Marine Science, 7, (2020): 72, doi:10.3389/fmars.2020.00072.Bacteria have been implicated as both a source and sink of hydrogen peroxide (H2O2), a reactive oxygen species which can both impact microbial growth and participate in the geochemical cycling of trace metals and carbon in natural waters. In this study, simultaneous H2O2 production and decay by twelve species of heterotrophic bacteria were evaluated in both batch and flow-through incubations. While wide species-to-species variability of cell-normalized H2O2 decay rate coefficients [2 × 10–8 to 5 × 10–6 hr–1 (cell mL–1)–1] was observed, these rate coefficients were relatively consistent for a given bacterial species. By contrast, observed production rates (below detection limit to 3 × 102 amol cell–1 hr–1) were more variable even for the same species. Variations based on incubation conditions in some bacterial strains suggest that external conditions may impact extracellular H2O2 levels either through increased extracellular production or leakage of intracellular H2O2. Comparison of H2O2 production rates to previously determined superoxide (O2–) production rates suggests that O2– and H2O2 production are not necessarily linked. Rates measured in this study indicate that bacteria could account for a majority of H2O2 decay observed in aqueous systems but likely only make a modest contribution to dark H2O2 production.This research was supported by NSF grant OCE-1131734/1246174 to BV and CH

Analysis and Comparation of SSD and HDD Technologies

Import 22/07/2015Jedním z faktorů, který limituje efektivní činnost počítačové jednotky, je výkonnost její klíčové součásti – pevného disku (hardwaru). Proto se výzkum v oblasti informačních technologií soustřeďuje na problematiku kapacity, rychlosti a aplikovatelnosti právě těchto komponentů výpočetní techniky. Je zajímavé, že výzkumná činnost v této oblasti přinesla dvě zcela odlišná technologická řešení. Jedním z nich je systém HDD, založený na principu pohyblivých mechanických částí, druhý - označovaný SSD - umožňuje ukládání, interpretaci a další aktivity s daty pomocí elektronických obvodů. Cílem této bakalářské práce je analýza a komparace technologií HDD a SDD datových úložišť jak v oblasti technických a finančních parametrů, tak i z možností aplikace. Autor však nezůstává u pouhé deskripce zjištěného stavu, ale zároveň navrhuje v konkrétně vybraném prostředí řešení, která by měla vést ke zvýšení efektivnosti využití IT jak pro studenty, tak i pedagogickou a správní činnost střediska.One of factors that limit the effective operation of the computer unit is the efficiency of its key components – the hard disk drive (hardware). Therefore, research in information technology is focused on the issue of capacity, speed and applicability of these very computer components. It is interesting that research activity in this area has brought two completely different technological solutions. One of them is the HDD system based on the principle of moving mechanical parts, the second - called SSD - allows storage, interpretation and other activities with data using electronic circuits. The aim of this bachelor thesis is to analyze and compare technologies of HDD and SDD storage both in technical and financial parameters as well as application possibilities. However, the author does not stop at mere description of the condition, but also suggests solutions in specific environment that should lead to an increase in the efficiency of utilization of IT for both students and teaching and administrative activities of the study centre.Prezenční545 - Institut ekonomiky a systémů řízenívýborn

How strong are correlations in strongly recurrent neuronal networks?

Cross-correlations in the activity in neural networks are commonly used to characterize their dynamical states and their anatomical and functional organizations. Yet, how these latter network features affect the spatiotemporal structure of the correlations in recurrent networks is not fully understood. Here, we develop a general theory for the emergence of correlated neuronal activity from the dynamics in strongly recurrent networks consisting of several populations of binary neurons. We apply this theory to the case in which the connectivity depends on the anatomical or functional distance between the neurons. We establish the architectural conditions under which the system settles into a dynamical state where correlations are strong, highly robust and spatially modulated. We show that such strong correlations arise if the network exhibits an effective feedforward structure. We establish how this feedforward structure determines the way correlations scale with the network size and the degree of the connectivity. In networks lacking an effective feedforward structure correlations are extremely small and only weakly depend on the number of connections per neuron. Our work shows how strong correlations can be consistent with highly irregular activity in recurrent networks, two key features of neuronal dynamics in the central nervous system

La protección de trabajadores a través de la estabilidad laboral reforzada: el caso de los pre-pensionados y su protección constitucional

Artículo de investigaciónEl actual diseño normativo colombiano en materia laboral encuentra en la institución de la estabilidad laboral reforzada un instrumento jurídico de uso por parte de los trabajadores, quienes acuden a esta para garantizar la protección de sus derechos laborales frente a situaciones como el despido o desmejoramiento de las condiciones laborales. En lo más reciente de la jurisprudencia, esta figura de protección fue extendida a las personas que se encuentran próximas a adquirir el estatus pensional. la Sentencia SU-003 de 2018, la cual genera un escenario de mayor protección jurídica frente a los derechos de los trabajadores que se encuentran finalizando su etapa productiva. Su desarrollo, lleva a clarificar el estado actual de titularidad de este derecho para los trabajadores colombianos próximos a pensionarse, evocando las razones por las cuales estos pueden ser cobijados por dicha protección, como consecuencia de la materialización de otros derechos y principios del Texto Constitucional.Introducción 1. Estabilidad laboral reforzada, su protección constitucional en el caso de los pre-pensionados. 2. Estabilidad laboral reforzada: normatividad y jurisprudencia. 3. Situaciones precisas sobre la aplicabilidad de la estabilidad laboral reforzada en Colombia 4. Conclusiones BibliografíaPregradoAbogad