Estimates of the Strouhal number from numerical models of convection

We determine the Strouhal number (hereafter St), which is essentially a nondimensional measure of the correlation time, from numerical calculations of convection. We use two independent methods to estimate St. Firstly, we apply the minimal tau-approximation (MTA) on the equation of the time derivative of the Reynolds stress. A relaxation time is obtained from which St can be estimated by normalising with a typical turnover time. Secondly, we calculate the correlation and turnover times separately, the former from the autocorrelation of velocity and the latter by following test particles embedded in the flow. We find that the Strouhal number is in general of the order of 0.1 to 1, i.e. rather large in comparison to the typical assumption in the mean-field theories that St << 1. However, there is a clear decreasing trend as function of the Rayleigh number and increasing rotation. Furthermore, for the present range of parameters the decrease of St does not show signs of saturation, indicating that in stellar convection zones, where the Rayleigh numbers are much larger, the Strouhal number may indeed be significantly smaller.Comment: 4 pages, 2 figures. To appear in a special volume of Astronomische Nachrichten for the conference 'Dynamos of the Sun, Stars & Planets', held in Freiburg, Oct 4th-6th, 200

Nicht-analoge französische und italienische Übersetzungen von restriktiven Partikeln im Roman Die Mittagsfrau von Julia Franck

The present paper discusses the translation of German nur and some synonymous restrictive particles into French and Italian in authorized literary translations. Only non-analogous translations of the restrictive particles have been considered, such as It. si limitò a sorridere for Germ. sie lächelte nur ('she limited herself to smiling' vs. 'she only smiled'). Three types of non-analogous equivalents of nur could be found in the data-base: cleft constructions, verbal periphrases and verb-infinitive combinations. The use of these Italian and French expressions seems to be constantly linked to co-textual features. The description of these non-analogous equivalents contributes to a better delineation of language-specific preferences concerning the encoding of restriction. Furthermore the description leads to helpful suggestions for translations from French/Italian into German, encouraging translators to substitute e.g. a finite, main verb (It. limitarsi) for a simple particle (Germ. nur) in order to get adequate solutions in German

The effect of household income on household consumption in China

China’s economic growth undoubtedly led to an increase in the standard of living. Nevertheless, the price that China paid for this remarkably fast growth since its opening up in 1978 cannot be neglected. Due to a restructuring of the economic growth model, inequality occurred to a certain extent and has been strengthened by Chinese institutional features. The current growth model is considered as unsustainable and prone to external shocks – whereat it could not rely on the household consumption. The latter is extremely low by international standards, wherefore several factors are held responsible. The aim of this paper is to measure the effect of income and other Chinese characteristics that are claimed to be responsible for negatively affecting the household consumption. By using a comprehensive survey from 2011, these effects are measured directly at the household level. Having an understanding of the magnitude of these effects, especially about the importance of household income, certain solutions are discussed

Imperial Janus: Patterns of Governance in the Western Borderlands of the Tsarist Empire

Why did the Tsarist Empire opt for different governance strategies in each of the territories of the Western Borderlands (here defined as Poland-Lithuania, the Baltic territories, Finland, and Hetman Ukraine)? The existing political science literature tends to reduce such a question to a distinction between direct and indirect rule, usually developing in the context of a Western European maritime empire. This literature falls short of explaining the Tsarist case and requires the addition of intervening variables concerning the role of local elites and leadership choice. Employing an interdisciplinary literature combining sources from political science, sociology and history, this dissertation develops a structural-institutional approach to explaining patterns of direct and indirect rule that emphasizes the strength and cohesion of local elites, their orientation towards the dominant unit, and the role of leadership choice in the dominant unit. In addition to better accounting for the policy trajectory of the Tsarist Empire, such an explanation can also be applied to other historical and contemporary political systems deciding between centralized and decentralized rule

Physical Properties of Iron Oxide Nanoparticles

Magnetic Resonance Imaging (MRI) relies heavily on contrast agents such that diagnosis of various diseases can be made with increased confidence. Current contrast agents for MRI depend on various chelated molecules composed of a toxic gadolinium ion, Gd3+. In 2006, a discovery was made connecting Nephrogenic Systemic Fibrosis (NSF) and these gadolinium based contrast agents (GBCAs). The connection between life threatening NSF and GBCAs stems from patients with pre-existing kidney malfunctions. It has been proposed that an alternative agent such as iron oxide nanoparticles (IONPs) be investigated. These IONPs theoretically will have similar responses in efficiency of improving the contrast of MRI images. To ensure the biocompatibility of these molecules we will investigate implementation of a biologically safe gold coating around the IONP. We will present what is observed in the characterization of these IONPs

The Actin-Severing Protein Cofilin Is Downstream Of Neuregulin Signaling, Is Regulated By The Tumor Suppressor Merlin, And Is Essential For Schwann Cell Myelination

Myelination is a complex process requiring coordination of directional motility and an increase in Schwann cell (SC) size to generate a multi-lamellar myelin sheath. Regulation of actin dynamics during myelination is poorly understood. However, it is known that myelin thickness is related to the abundance of neuregulin1-type III (NRG) expressed on the axon surface. NRG binding to ErbB2/3 receptors on the Schwann cell surface initiates signaling cascades necessary for myelination. We identify cofilin1, an actin depolymerizing and severing protein, as a downstream target of NRG-ErbB2/3 signaling in rat SC. A five minute exposure of SCs to NRG triggers phosphorylation of ErbB2 with concomitant dephosphorylation, and activation, of cofilin, and its upstream regulators, LIM domain kinase (LIMK) and Slingshot-1 phosphatase (SSH). This leads to cofilin activation and recruitment to the leading edge of the SC plasma membrane. These changes are associated with rapid plasma membrane expansion yielding a 35–50% increase in SC size within 30 minutes of NRG1 exposure. Cofilin1-deficient SCs increase phosphorylation of ErbB2, ERK, focal adhesion kinase, and paxillin in response to NRG, but fail to increase in size possibly due to stabilization of unusually long focal adhesions. Cofilin1-deficient SCs co-cultured with sensory neurons fail to elaborate myelin. Ultrastructural analysis reveals that they unsuccessfully segregate or engage axons and form only patchy basal lamina. After 48 hours of co-culturing with neurons, cofilin-deficient SCs fail to align and elongate on axons and often adhere to the underlying substrate rather than to axons. We show that the Neurofibromatosis Type II (NF2) tumor suppressor, merlin, is an upstream regulator of cofilin1, and that merlin knockdown in Schwann cells inhibits their elaboration of normal myelin sheaths in vitro. Merlin-deficient SCs form shorter myelin segments in DRG neuron/SC co-cultures. Merlin-deficient Schwann cells have increased levels of both active Rac (Rac-GTP) and F-actin indicative of a stable actin cytoskeleton. Surprisingly merlin-deficient Schwann cells fail to dephosphorylate and activate cofilin1 in response to NRG stimulation. Inhibition of LIMK restores the ability of merlin-deficient SCs to activate cofilin in response to NRG. In developing rat sciatic nerve, merlin becomes hyper-phosphorylated at S518 during the time of peak myelin formation. During this time, cofilin is localized to the inner mesaxon, and subsequently to Schmidt-Lanterman incisures in mature myelin. This study: 1) identifies cofilin and its upstream regulators, LIMK and SSH, as end targets of a NRG-ErbB2/3 signaling pathway in Schwann cells, 2) demonstrates that cofilin modulates actin dynamics in Schwann cells allowing for motility needed to effectively engage and myelinate axons, 3) shows that merlin regulates NRG-ErbB2/3-cofilin-actin signaling during SC myelination to determine the myelin segment length

Using Macroinvertebrates to Test the Water Quality of Lake Nacogdoches

The target of this assessment was to conduct a water quality test on Lake Nacogdoches in Nacogdoches TX. Lake Nacogdoches is operated by the city of Nacogdoches for municipal water supply and recreation. One of the tests that we ran to determine water quality was a macroinvertebrates test. To do this, we kicked up substrate to expose the organisms burrowed deep in the soil and caught them in a d-frame kick net. We then used our macroinvertebrate key to identify the organism and find the level of biodiversity in the lake. This test is essential because biodiversity affects climate stability, the food web, and the maintenance of the entire ecosystem. Therefore, this test will tell us the overall health of the ecosystem as well. Water quality tests will be used to find any pollutants in the area. Testing at the boat ramps by the dam where the water is taken to the Nacogdoches surface water treatment facility is key to find pollution that could be entering our water. At both the East and Westside park, we collected water samples over three different days and then took the samples to the Environmental Assessment lab for testing. Using a thermometer, Hq40d Probe, spectrophotometer, and colorimeter, we tested the samples for temperature, PH, dissolved oxygen, and nitrite (low range)

Beyond Access: A Principal’s Behaviors Displayed In The Implementation Of A District-Wide Initiative Focused On Students With Disabilities

The civil rights movement provided the foundation for students with disabilities to access education in the same settings as their nondisabled peers. However, placement in the same settings is not a guarantee of equitable educational experiences. This study was an exploration of the behaviors of a principal in the implementation of a district initiative for equitable educational opportunities for students with disabilities, with a focus on the co-teaching service delivery model. The study was the means used to explicitly explore how or if those behaviors aligned with the characteristics of the social justice leadership framework. Qualitative methodology, specifically an instrumental case study design, was the approach chosen to explore these perceptions within one school in a large urban school district in the Southeastern United States. The selected participants from the site were a principal and a special education teacher. The collection of various data sources occurred via semi-structured interviews and a review of pertinent documents. Open coding, pattern coding, and codeweaving commenced to develop themes. The following themes emerged: a willingness to identify problems, a solutions-oriented approach, and an inclusive mindset. The findings demonstrated that the principal’s behaviors in the implementation of the district initiative aligned with several characteristics of social justice leadership. The study included a further analysis of the descriptions of the principal’s behaviors through the lens of several constructs of social justice leadership. The principal displayed a connection to socially just pedagogy, an inclusive and democratic mindset, a relational and caring demeanor, and an action-oriented and transformational leadership style. Findings from this study could contribute to the extant literature and practice in the following areas: the impact of principal behaviors on initiative implementation, instructional leadership practices for students with disabilities, and leadership priorities for recruitment. There is a need for further research on social justice leadership at the school and district level and leadership development in special education. This study also suggests further research into the design and implementation of co-teaching models for students with disabilities