The transition in settling velocity of surfactant-covered droplets from the Stokes to the Hadamard-Rybczynski solution

The exact solution for a small falling drop is a classical result by Hadamard and Rybczynski. But experiments show that small drops fall slower than predicted, giving closer agreement with Stokes' result for a falling hard sphere. Increasing the drop size, a transition between these two extremes is found. This is due to surfactants present in the system, and previous work has led to the stagnant-cap model. We present here an alternative approach which we call the continuous-interface model. In contrast to the stagnant-cap model, we do not consider a surfactant advection-diffusion equation at the interface. Taking instead the normal and tangential interfacial stresses into account, we solve the Stokes equation analytically for the falling drop with varying interfacial tension. Some of the solutions thus obtained, e.g. the hovering drop, violate conservation ofenergy unless energy is provided directly to the interface. Considering the energy budget of the drop, we show that the terminal velocity is bounded by the Stokes and the Hadamard-Rybczynski results. The continuous-interface model is then obtained from the force balance for surfactants at the interface. The resulting expressions gives the transition between the two extremes, and also predicts that the critical radius, below which drops fall like hard spheres, is proportional to the interfacial surfactant concentration. By analysing experimental results from the literature, we confirm this prediction, thus providing strong arguments for the validity of the proposed model

Gollevarre Revisited – Reindeer, Domestication and Pastoral Transformation

The Gollevarre complex near the River Tana in Finnmark, Norway, consists of 2,685 pitfalls and a campsite with the remains of 16 turf dwellings, all dated to the period 1200–1650 CE. The enormous amount of reindeer bones at the campsite testifies to both largescale hunting and production of bone artefacts for a market. Why did this activity endand did its termination have any connection with pastoral development which took place at the same time? These questions were addressed through an expedition to Gollevarreby the archaeologists Sven Donald Hedman and Bjørnar Olsen, the biologist Knut Røed and the anthropologist Ivar Bjørklund. With the aid of 281 DNA samples from Gollevarreand other sites in Finnmark, we concluded that a) the emergence of pastoralism did not depend on the domestication of wild reindeer, since b) there were no genetic relationsbetween the old stock of wild reindeer and the current stock of domesticated reindeer. Thus, the emergence of pastoralism in the 17th century seemed to be the result of theimport of domesticated animals. Alternatively, but so far without DNA-proven facts, the current stock might reflect an old, but small, population of domesticated reindeer kept for transport purposes

Commentary: Sulfur Dioxide Contributes to the Cardiac and Mitochondrial Dysfunction in Rats

Commen

PERM Hypothesis: the fundamental machinery able to elucidate the role of xenobiotics and hormesis in cell survival and homeostasis

In this article the Proteasome, Endoplasmic Reticulum and Mitochondria (PERM) hypothesis is discussed. The complex machinery made by three homeostatic mechanisms involving the proteasome (P), endoplasmic reticulum (ER) and mitochondria (M) is addressed in order to elucidate the beneficial role of many xenobiotics, either trace metals or phytochemicals, which are spread in the human environment and in dietary habits, exerting their actions on the mechanisms underlying cell survival (apoptosis, cell cycle regulation, DNA repair and turnover, autophagy) and stress response. The "PERM hypothesis" suggests that xenobiotics can modulate this central signaling and the regulatory engine made fundamentally by the ER, mitochondria and proteasome, together with other ancillary components such as peroxisomes, by acting on the energetic balance, redox system and macromolecule turnover. In this context, reactive species and stressors are fundamentally signalling molecules that could act as negative-modulating signals if PERM-mediated control is offline, impaired or dysregulated, as occurs in metabolic syndrome, degenerative disorders, chronic inflammation and cancer. Calcium is an important oscillatory input of this regulation and, in this hypothesis, it might play a role in maintaining the correct rhythm of this PERM modulation, probably chaotic in its nature, and guiding cells to a more drastic decision, such as apoptosis. The commonest effort sustained by cells is to maintain their survival balance and the proterome has the fundamental task of supporting this mechanism. Mild stress is probably the main stimulus in this sense. Hormesis is therefore re-interpreted in the light of this hypothetical model and that experimental evidence arising from flavonoid and hormesis reasearch

A tragedy of errors? Institutional dynamics and land tenure in Finnmark, Norway

-Reindeer herding in Finnmark has been widely perceived during the last few decades as a perfect example of the tragedy of the commons. The present article claims that this discourse relies on flawed assumption regarding land tenure. Our historical analysis of the term ‘common’ in relation to resources in Finnmark shows the term to reflect a misunderstanding of local categories, practices, and concerns related to pastures, territories, and natural resources more generally. In this sense, it exposes a case of ‘mistaken identity’ between the formal legal conception of ‘commons’ and the customary rules and thinking of reindeer herders. We turn to different strands of critical institutionalism to analyse the processes of institutional change that have allowed these errors and misunderstandings to be formalised and naturalised in the current governance system. We show that a process of institutional bargaining between the Norwegian Parliament, the Sámi Parliament, and the International Labour Organisation has recently re-enforced an alien conception of a ‘commons’ to which ambiguous groups of people have equivocal rights. In parallel, a process of institutional layering of new regulatory actors and rules on top of existing ones has taken place. This regulatory ratcheting has resulted in the blurring of the authorities and jurisdictions intrinsic in the customary tenure system. Moreover, the new layers of regulations have actively overemphasized the Sámi customary obligation of sharing resources to legitimize the new, ambiguous, conception of commons. This process is explained as one of institutional bricolage based on naturalisation by analogy and authority processes that allow certain powerful actors to influence the production of institutional arrangements favourable to them. All three processes underline the negotiated, dynamic nature of institutional change. We propose this integrative analysis of institutional and general social dynamics is beneficial in studying commons as everyday practices affecting natural resource governance

Flipping the Classroom? From Text to Video in Teaching Russian Grammar

Source at https://scholarsarchive.byu.edu/rlj/.The notion of a “flipped classroom” has received considerable attention in recent years. This article reports on a project in which an instructor and two students co-created teaching materials to facilitate flipping the classroom. The purpose of the article is twofold. First, we explore some aspects of flipped classrooms in Russian language courses. Second, we reflect on the opportunities and limitations of student involvement in pedagogical development

Validation of the adult eating behavior questionnaire in a Norwegian sample of adolescents

Eating behaviors are related to health and well-being. To examine stability and change in eating behaviors throughout life, developmentally appropriate measures capturing the same eating behavior dimensions are needed. The newly developed Adult Eating Behavior Questionnaire (AEBQ) builds on the well-established parent-reported Children's Eating Behavior Questionnaire (CEBQ), and together with the corresponding Baby Eating Behavior Questionnaire (BEBQ), these questionnaires cover all ages. However, validation studies on adolescents are relatively sparse and have yielded somewhat conflicting results. The present study adds to existing research by testing the psychometric properties of the AEBQ in a sample of 14-year-olds and examining its construct validity by means of the parent-reported CEBQ. The current study uses age 14 data (analysis sample: n = 636) from the ongoing Trondheim Early Secure Study, a longitudinal study of a representative birth cohort of Norwegian children (baseline: n = 1007). Confirmatory factor analysis (CFA) was conducted to test the factorial validity of AEBQ. Construct validity was examined by bivariate correlations between AEBQ subscales and CEBQ subscales. CFAs revealed that a 7-factor solution of the AEBQ, with the Hunger scale removed, was a better-fitting model than the original 8-factor structure. The 7-factor model was respecified based on theory and model fit indices, resulting in overall adequate model fit (χ2 = 896.86; CFI = 0.924; TLI = 0.912; RMSEA = 0.05 (90% CI: 0.043, 0.051); SRMR = 0.06). Furthermore, small-to-moderate correlations were found between corresponding AEBQ and CEBQ scales. This study supports a 7-factor solution of the AEBQ without the Hunger scale and provide evidence of its construct validity in adolescents. Several of the CEBQ subscales were significantly associated with weight status, whereas this was the case for only one of the AEBQ scales

"To face it like a man": Exploring Male Anxiety in Dracula and the Sherlock Holmes Canon

This thesis posits that the genre of the male quest romance, highly popular during the British fin de siècle, was a literary response to increased male anxiety during that period. Reading works belonging to this genre, this thesis sees writers treating approaches to masculinity not as something simple and monolithic, but as diverse and fraught with uncertainty of definition. This thesis demonstrates that the ways in which men in these novels deal with threats to their masculine identity, clearly show that masculinity is experienced as a concept no less complicated than femininity. The specific threats treated here are the role of women, men's sexuality, and mental illness. In the interest of equality, and in an academic setting where gender studies are frequently synonymous with women's studies , it is hoped that an academic approach to the male quest romance genre will lead to new understandings of the complexity of masculinity as a basis for identity. The introduction explains the socio-cultural context in which the primary texts were written, clarifies important terms and gives an overview of which theories this thesis draws on. Chapter 1 discusses how the Sherlock Holmes tales explore unconventional models of masculinity, while Chapter 2 argues that Dracula reinforces certain traditional aspects of gender roles in order to counter the destabilisation of masculine identity. Findings and new insights are outlined in the conclusion