Steady Viscous Flow in a Triangular Cavity

Steady recirculating viscous flow inside an equilateral triangular cavity is generated by translating one side. The Navier-Stokes equations are solved numerically using finite difference on a transformed geometry. The results show a primary eddy and a series of secondary eddies at the stagnant corner. For high Reynolds numbers the interior of the primary eddy has constant vorticity, but its value cannot be predicted by the mean-squared law

Beyond 2020: How General Education Archaeology Curricula Should Adapt to the COVID-19 Pandemic

Archaeology often justifies its existence by invoking the trope that we must learn about the past in order to create a better future. The COVID-19 pandemic is itself an event that will enter the historical record. Thus, the universality of this public health crisis is a unique opportunity to assess the relevance of university-level archaeology curricula to our present historical moment. We studied an upper division general education course on the archaeology of complex societies at a public liberal arts college in California. The instrument of data collection was a questionnaire administered at the end of the Fall 2020, Spring 2021, and Spring 2022 semesters. Students read an article about archaeological approaches to pandemics, then reflected on how it connected to course content and to their own experiences during the COVID-19 pandemic. Content analysis of student responses suggests that course themes of complex societies, the environment, archaeological evidence, the future, and social hierarchy resonated most with students on both intellectual and personal levels. We also identified emergent concerns with diseases (COVID-19 and others) and cultural responses to them, employment status, and psychological effects, suggesting that these themes are increasingly relevant to archaeology students during and beyond the COVID-19 pandemic

Effects of white-tailed deer herbivory on upland plant communities in the Piedmont of South Carolina

White-tailed deer (Odocoileus virginianus) is an important game species and the largest native herbivore in South Carolina. Intense deer herbivory can result in browse lines, reduced regeneration of tree species, and the extirpation of plant species. The impact of white-tailed deer has been studied throughout much of its northern range, but there has been little long-term research into the impact of deer on forests communities in the Southeast. This study measures impacts of deer herbivory 13 years after clearcutting upland hardwood stands in the Clemson Experimental Forest by comparing forest and plant communities inside and outside exclosures. An initial study conducted in 2005, 1 year after the clearcut, concluded that deer density had no impact on these communities. To determine the long-term impacts of herbivory, the plots were resurveyed 13 years later. Regeneration of seedling, sapling and overstory oaks was unimpacted by deer herbivory (p=.61, p=.58, p=.45). In fact, the plots outside the exclosures had a higher population of 4in DBH oaks compared to the plots inside enclosures (p=0.09). There was significantly higher plant species richness outside the exclosures compared to inside (p=0.08). Shannon’s diversity index was not statistically different between treatments (p\u3e0.1). Both treatments had a similar number of invasive species (p=0.81). Exclosures had 5,000 more Japanese honeysuckle (Lonicera japonica) per acre compared to outside the exclosure. There was significantly higher vine regeneration inside the exclosures (

Validation of ERS-1 environmental data products

Evaluation of the launch-version algorithms used by the European Space Agency (ESA) to derive wind field and ocean wave estimates from measurements of sensors aboard the European Remote Sensing satellite, ERS-1, has been accomplished through comparison of the derived parameters with coincident measurements made by 24 open ocean buoys maintained by the National Oceanic and Atmospheric Administration). During the period from November 1, 1991 through February 28, 1992, data bases with 577 and 485 pairs of coincident sensor/buoy wind and wave measurements were collected for the Active Microwave Instrument (AMI) and Radar Altimeter (RA) respectively. Based on these data, algorithm retrieval accuracy is estimated to be plus or minus 4 m/s for AMI wind speed, plus or minus 3 m/s for RA wind speed and plus or minus 0.6 m for RA wave height. After removing 180 degree ambiguity errors, the AMI wind direction retrieval accuracy was estimated at plus or minus 28 degrees. All of the ERS-1 wind and wave retrievals are relatively unbiased. These results should be viewed as interim since improved algorithms are under development. As final versions are implemented, additional assessments should be conducted to complete the validation

Analysis of Function Component Complexity for Hypercube Homotopy Algorithms

Probability-one homotopy algorithms are a class of methods for solving nonlinear systems of equations that globally convergent from an arbitrary starting point with probability one. The essence of these homotopy algorithms is the construction of a homotopy map p-sub a and the subsequent tracking of a smooth curve y in the zero set p-sub a to the -1 (0) of p-sub a. Tracking the zero curve y requires repeated evaluation of the map p-sub a, its n x (v + 1) Jacobian matrix Dp-sub a and numerical linear algebra for calculating the kernel of Dp-sub a. This paper analyzes parallel homotopy algorithms on a hypercube, considering the numerical algebra, several communications topologies and problem decomposition strategies, functions component complexity, problem size, and the effect of different component complexity distributions. These parameters interact in complicated ways, but some general principles can be inferred based on empirical results

Unit Tangent Vector Computation for Homotopy Curve Tracking on aHypercube

Probability-one homotopy methods are a class of methods for solving nonlinear systems of equations that are globally convergent from an arbitrary starting point. The essence of all such algorithms is the construction of an appropriate homotopy map and subsequent tracking of some smooth curve in the zero set of the homotopy map. Tracking a homotopy curve involves finding the unit tangent vectors at different points along the zero curve. Because of the way a homotopy map is constructed, the unit tangent vector at each point in the zero curve of a homotopy map (symbols) is in the kernel of the Jacobian matrix (symbols). Hence tracking the zero curve of a homotopy map involves finding the kernel of the Jacobian matrix (symbols). The Jacobian matrix (symbols) is a n x (n + 1) matrix with full rank. Since the accuracy of the unit tangent vector is very important, on orthogonal factorization instead of an LU factorization of the Jacobian matrix is computed. Two related factorizations, namely QR and LQ factorization, are considered here. This paper presents computational results showing the performance of several different parallel orthogonal factorization/triangular system solving algorithms on a hypercube. Since the purpose of this study is to find ways to parallelize homotopy algorithms, it is assumed that the matrices are small, dense, and have a special structure such as that of the Jacobian matrix of a homotopy map

Steady Viscous Flow in a Trapezoidal Cavity

The flow in a trapezoidal cavity (including the rectangular and triangular cavities) with one moving wall is studied numerically by finite differences with special treatment in the corners. It is found that streamlines and vorticity distributions are sensitive to geometric changes. The mean square law for core vorticity is valid for the rectangle but ceases to be valid for the triangular cavity

An Efficient System for Heterologous Expression of Secondary Metabolite Genes in Aspergillus nidulans

This document is the Accepted Manuscript version of a Published Work that appeared in final form in the Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/ja401945a.Fungal secondary metabolites (SMs) are an important source of medically valuable compounds. Genome projects have revealed that fungi have many SM biosynthetic gene clusters that are not normally expressed. To access these potentially valuable, cryptic clusters, we have developed a heterologous expression system in Aspergillus nidulans. We have developed an efficient system for amplifying genes from a target fungus, placing them under control of a regulatable promoter, transferring them into A. nidulans and expressing them. We have validated this system by expressing non-reducing polyketide synthases of Aspergillus terreus and additional genes required for compound production and release. We have obtained compound production and release from six of these NR-PKSs and have identified the products. To demonstrate that the procedure allows transfer and expression of entire secondary metabolite biosynthetic pathways, we have expressed all the genes of a silent A. terreus cluster and demonstrate that it produces asperfuranone. Further, by expressing the genes of this pathway in various combinations, we have clarified the asperfuranone biosynthetic pathway. We have also developed procedures for deleting entire A. nidulans SM clusters. This allows us to remove clusters that might interfere with analyses of heterologously expressed genes and to eliminate unwanted toxins