Chaotic Advection at the Pore Scale: Mechanisms, Upscaling and Implications for Macroscopic Transport

The macroscopic spreading and mixing of solute plumes in saturated porous media is ultimately controlled by processes operating at the pore scale. Whilst the conventional picture of pore-scale mechanical dispersion and molecular diffusion leading to persistent hydrodynamic dispersion is well accepted, this paradigm is inherently two-dimensional (2D) in nature and neglects important three-dimensional (3D) phenomena. We discuss how the kinematics of steady 3D flow at the porescale generate chaotic advection, involving exponential stretching and folding of fluid elements,the mechanisms by which it arises and implications of microscopic chaos for macroscopic dispersion and mixing. Prohibited in steady 2D flow due to topological constraints, these phenomena are ubiquitous due to the topological complexity inherent to all 3D porous media. Consequently 3D porous media flows generate profoundly different fluid deformation and mixing processes to those of 2D flow. The interplay of chaotic advection and broad transit time distributions can be incorporated into a continuous-time random walk (CTRW) framework to predict macroscopic solute mixing and spreading. We show how these results may be generalised to real porous architectures via a CTRW model of fluid deformation, leading to stochastic models of macroscopic dispersion and mixing which both honour the pore-scale kinematics and are directly conditioned on the pore-scale tomography.Comment: 43 page

Tracking movements of Athene owls: the application of North American experiences to Europe

Seguimiento de los desplazamiento de los mochuelos del género Athene: aplicación de las experiencias norteamericanas a Europa Migración y dispersión son procesos importantes desde el punto de vista de la ecología y la evolución, y entenderlos es un requisito importante para los programas de conservación de las especies. El mochuelo de madriguera, Athene cunicularia, el equivalente norteamericano del mochuelo europeo, A. noctua, es migratorio en las zonas septentrionales de su área de acción. En Canadá sus poblaciones han disminuido de forma notoria, y se han clasificado como amenazadas. Se han estudiado los desplazamientos del mochuelo de madriguera utilizando el anillado, la telemetría VHF, los isótopos estables, la genética (ADN), los geolocalizadores y los transmisores por satélite. Los geolocalizadores y los transmisores por satélite proporcionan la información más fiable sobre las migraciones, pero para su buen funcionamiento dependen de la exposición a la luz solar, que es limitada en el caso de las rapaces nocturnas. Los hallazgos de animales anillados, y los flujos migratorios invernales del mochuelo común hacia España, incluyendo las Islas Baleares, indican que pueden estarse dando desplazamientos migratorios. Un estudio mediante isótopos estables podría determinar si entre los mochuelos que invernan en el sur de Europa, se incluyen mochuelos del norte de Europa. Palabras clave: Athene, Desplazamientos, Migración, Dispersión, Técnicas.Migration and dispersal are important ecological and evolutionary processes and understanding them is a requirement for species conservation efforts. Burrowing owl, Athene cunicularia, the North American equivalent of little owl, A. noctua, is migratory in the northern parts of its range. In Canada their populations have declined dramatically and are classified as endangered. Movements of burrowing owls have been studied using banding (ringing), VHF telemetry, stable isotopes, genetics (DNA), geolocators and satellite transmitters. Geolocators and satellite transmitters provide the most reliable information about migrations but to operate successfully they are both dependent upon exposure to sunlight, which can be limited for nocturnal owls. Ringing encounters and winter influxes of little owls into Spain, including the Balearic Islands, indicate that some migration movement may be occurring. A stable isotope study could determine if wintering owls in southern Europe includes owls originating in northern Europe. Key words: Athene, Movements, Migration, Dispersal, Techniques.Seguimiento de los desplazamiento de los mochuelos del género Athene: aplicación de las experiencias norteamericanas a Europa Migración y dispersión son procesos importantes desde el punto de vista de la ecología y la evolución, y entenderlos es un requisito importante para los programas de conservación de las especies. El mochuelo de madriguera, Athene cunicularia, el equivalente norteamericano del mochuelo europeo, A. noctua, es migratorio en las zonas septentrionales de su área de acción. En Canadá sus poblaciones han disminuido de forma notoria, y se han clasificado como amenazadas. Se han estudiado los desplazamientos del mochuelo de madriguera utilizando el anillado, la telemetría VHF, los isótopos estables, la genética (ADN), los geolocalizadores y los transmisores por satélite. Los geolocalizadores y los transmisores por satélite proporcionan la información más fiable sobre las migraciones, pero para su buen funcionamiento dependen de la exposición a la luz solar, que es limitada en el caso de las rapaces nocturnas. Los hallazgos de animales anillados, y los flujos migratorios invernales del mochuelo común hacia España, incluyendo las Islas Baleares, indican que pueden estarse dando desplazamientos migratorios. Un estudio mediante isótopos estables podría determinar si entre los mochuelos que invernan en el sur de Europa, se incluyen mochuelos del norte de Europa. Palabras clave: Athene, Desplazamientos, Migración, Dispersión, Técnicas

Resilience: Easy to use but hard to define

First conceptualized in the 1970s, resilience has become a popular term in the ecological literature, used in the title, abstract, or keywords of approximately 1% of papers identified by ISI Web of Science in the field of environmental sciences and ecology in 2011. However, many papers make only passing reference to the term and do not explain what resilience means in the context of their study system, despite there being a number of possible definitions. In an attempt to determine how resilience is being used in ecological studies, we surveyed 234 papers published between 2004 and 2011 that were identified under the topic “resilience” by ISI Web of Science. Of these, 38% used the word resilience fewer than three times (often in the abstract or keyword list), 66% did not define the term, and 71% did not provide a citation to the resilience literature. Studies that defined resilience most often discussed it as pertaining to an entire ecosystem under continuous rather than discrete disturbance. Given the complex nature of this concept, we believe that care should be taken to properly describe what is meant by the term resilience in ecological studies

Comprehensive Review of Accounting: A Case-By-Case Study

This thesis was prepared to investigate a variety of accounting scenarios to further learn and challenge student’s notion of accounting. These accounting scenarios were in the form of 11 case studies done over the course of September 2020 to April 2021. These case studies highlighted a wide variety of accounting concepts, and even challenged students to a case competition highlighted in cases 6 through 10. These case studies not only challenged students to think about accounting concepts in a different light, but also to learn more about the field they are going into through personalized cases. These personalized cases allowed students to give their input about accounting concepts, learn more about accounting professionals, and learn more about their role in accounting. The case studies done in this thesis challenges accounting students to learn concepts not standardly taught in the classroom, and sets up success in the accounting professional field

Biogeochemical Analysis of Ancient Pacific Cod Bone Suggests Hg Bioaccumulation was Linked to Paleo Sea Level Rise and Climate Change

Deglaciation at the end of the Pleistocene initiated major changes in ocean circulation and distribution. Within a brief geological time, large areas of land were inundated by sea-level rise and today global sea level is 120 m above its minimum stand during the last glacial maximum. This was the era of modern sea shelf formation; climate change caused coastal plain flooding and created broad continental shelves with innumerable consequences to marine and terrestrial ecosystems and human populations. In Alaska, the Bering Sea nearly doubled in size and stretches of coastline to the south were flooded, with regional variability in the timing and extent of submergence. Here we suggest how past climate change and coastal flooding are linked to mercury bioaccumulation that could have had profound impacts on past human populations and that, under conditions of continued climate warming, may have future impacts. Biogeochemical analysis of total mercury (tHg) and δ13C/δ15N ratios in the bone collagen of archeologically recovered Pacific Cod (Gadus macrocephalus) bone shows high levels of tHg during early/mid-Holocene. This pattern cannot be linked to anthropogenic activity or to food web trophic changes, but may result from natural phenomena such as increases in productivity, carbon supply and coastal flooding driven by glacial melting and sea-level rise. The coastal flooding could have led to increased methylation of Hg in newly submerged terrestrial land and vegetation. Methylmercury is bioaccumulated through aquatic food webs with attendant consequences for the health of fish and their consumers, including people. This is the first study of tHg levels in a marine species from the Gulf of Alaska to provide a time series spanning nearly the entire Holocene and we propose that past coastal flooding resulting from climate change had the potential to input significant quantities of Hg into marine food webs and subsequently to human consumers

(The) contributions of the Tractarians to English literature.

Thesis (M.A.)--Boston Universit

Deception in Interpersonal Settings: The Relationship Between the Content of an Excuse and its Recipient

A correlational study investigated the nature of excuses, including the relationship of excuse complexity, uniqueness, frequency, and success to the level of knowledge the recipient has about the excuse giver. Analysis of results from responses of 121 participants to questionnaires describing excuses to employers, teachers, parents, and spouse/boy/girlfriends found that the complexity and uniqueness of excuses vary positively with the knowledge level of the recipient, but only when an unequal power relationship exists between the recipient and the excuse giver. Excuses to recipients with a low personal knowledge level of the excuse giver, such as employers or teachers, tended to be simple in nature, contained a minimum amount of information, and were usually common and frequently occurring. In contrast, excuses to recipients with a high personal knowledge of the excuse giver, such as parents who lived with the participants, tended to be complex in nature, contained significantly larger amounts of information, were generally more specific to the excuse giver and less frequently occurring. Old excuses were used more than new excuses in all contexts. Previously used excuses were also more frequent in low or neutral confidence conditions, and were more likely to be successful. Excuses were more successful to employers or teachers than to parents or spouse/boy girlfriends. Different categories emerged for different recipients of the excuses: the illness category was used most in the work context, and the miscellaneous category was used most in the parent and spouse/boy/girlfriend contexts. The influence of external control, and short and long term intimacy factors on the nature of excuses was discussed

A Double-Edged Sword: Organizational Culture in Multicultural Organizations

The primary premise explored in this paper is that organizational culture has the potentialfor even greater impact in multicultural organizations than mono-cultural ones because an organization\u27s culture can intensify both the benefits and the challenges of employee cultural diversity, and thus indirectly, affect organizational performance, organizational learning and competitive advantage. The assumptions underlying this contention and relationships among variables that contribute to the impact are explored in this paper, along with practical organizational implications. This study analyzes the dimensions of the \u27vitality of development\u27 of banking systems. Fuzzy synthetic decision analysis was used to construct and evaluate an index of the vitality of training, assigning and development, to offer banks new perspectives and methods of assessment. In this study, we analyze a vitality index for human resources development in banks. As regards uncertainty, the factor weights for the vitality index were determined by using the Fuzzy Delphi Method (FDM). Through the process of fuzzy synthetic decision (FSD) analysis, the model calculated the relative importance for each dimension of the mean factor. In this empirical study of commercial banks, the priority rank for the five dimensions are as follow: Efficiency, Leadership, Business Culture, Talents and Strategy