Dual weighted residual based error control for nonstationary convection-dominated equations: potential or ballast?

Even though substantial progress has been made in the numerical approximation of convection-dominated problems, its major challenges remain in the scope of current research. In particular, parameter robust a posteriori error estimates for quantities of physical interest and adaptive mesh refinement strategies with proved convergence are still missing. Here, we study numerically the potential of the Dual Weighted Residual (DWR) approach applied to stabilized finite element methods to further enhance the quality of approximations. The impact of a strict application of the DWR methodology is particularly focused rather than the reduction of computational costs for solving the dual problem by interpolation or localization.Comment: arXiv admin note: text overlap with arXiv:1803.1064

A first principles simulation of rigid water

We present the results of Car-Parrinello (CP) simulations of water at ambient conditions and under pressure, using a rigid molecule approximation. Throughout our calculations, water molecules were maintained at a fixed intramolecular geometry corresponding to the average structure obtained in fully unconstrained simulations. This allows us to use larger time steps than those adopted in ordinary CP simulations of water, and thus to access longer time scales. In the absence of chemical reactions or dissociation effects, these calculations open the way to ab initio simulations of aqueous solutions that require timescales substantially longer than presently feasible (e.g. simulations of hydrophobic solvation). Our results show that structural properties and diffusion coefficients obtained with a rigid model are in better agreement with experiment than those determined with fully flexible simulations. Possible reasons responsible for this improved agreement are discussed

Horror Literacy: Why We Write the Stories that Scare Readers

Children’s books often have animals as central characters with the animals displaying human traits in order to explore basic values in a general manner, or poke fun and invert values in order to provide gentle criticism and moral lessons. Seldom, if ever, do children’s books aim to scare readers or invert values and call them into question. In recent years, however, a few children’s books have begun to rewrite classics like Clifford The Big Red Dog in order to introduce elements through grotesque, irrelevant, cynicism, or horror. Such a rewriting is called a remix. It can be simply an inversion of techniques, an infusion of skeptical outlook, or an introduction of negative or horrifying possibilities. Among horror writers, few have the reputation for pessimism and nihilism as does H.P. Lovecraft. His pessimistic view of human progress and human history and his view that the whole of modern life rests on a grounding in ancient creatures who were overcome at one point but threaten modern values in human existence is unique. As one who studies horror writing and horror films as a genre, I wondered what horror writers and their techniques might do to guide a remix of a classic children’s book. The book I chose was Click Clack Moo by Doreen Cronin, an illustrated tale of barnyard animals who commandeer a typewriter and stage a rebellion against a farmer, demanding creature comforts such as electric blankets. Throughout my project, I created several remixes of Click Clack Moo. I rewrote this tale and altered the illustrations so I introduced elements of horror, and pessimistic points of view and behavior drawn loosely from Lovecraft’s works, especially “The Dunwich Horror ,” among others. The result is a remix called “Click Clack Cthulhu.” To accompany my research on horror writers, I created two additional remixes that highlighted horror writing with a female influence, as well as a male perspective. I accompanied this remix with interviews of female horror writers to probe the modern techniques of horror writing along with their motivations. From my research, I conclude that writers love to write horror as a way to write about personal traumatic events in order to gain control of them and bring order through personal hurt and chaos into literature. But also, horror writing is fun for the author and the reader

The Use of Proteomic Technologies to Identify Serum Glycoproteins for the Early Detection of Liver and Prostate Cancers

The application of proteomic technologies to identify serum glycoproteins is an emerging technique to identify new biomarkers indicative of disease severity. Many of these newly evolving protein-profiling methodologies have evolved from previous global protein expression profiling studies such as those involving SELDI-TOF-MS technologies. Though the SELDI approach could distinguish disease from normal by utilizing protein patterns as shown herein with the HCC study of chapter II, it was unable to offer sequence information on the selected peaks, and did not have the ability to analyze the entire dynamic range of the serum/plasma proteome. To address these deficiencies, new strategies that incorporate the use of differential lectin-based glycoprotein capture and targeted immuno-based assays have been developed. The carbohydrate binding specificities of different lectins offers a biological affinity approach that both complements existing mass spectrometer capabilities and retains automated throughput options. A prostate cancer study using disease stratified samples is utilized herein to determine whether lectin capture can identify glycoproteins, which are indicative of different stages of prostate disease. By utilizing upfront lectin fractionation we show here evidence of glycoproteins and glycoprotein isoforms, which are specific to cancer progression. In addition, the incorporation of lectin fractionation followed by albumin depletion allows for a more in depth analysis of the entire dynamic range of the human serum and plasma proteome. Taken together we believe this approach is an attractive strategy for the discovery of proteins indicative of the early detection of liver and prostate cancers

The Urbach tail in silica glass from first principles

We present density-functional theory calculations of the optical absorption spectra of silica glass for temperatures up to 2400 K. The calculated spectra exhibit exponential tails near the fundamental absorption edge that follow the Urbach rule, in good agreement with experiments. We also discuss the accuracy of our results by comparing to hybrid exchange correlation functionals. By deriving a simple relationship between the exponential tails of the absorption coefficient and the electronic density-of-states, we establish a direct link between the photoemission and the absorption spectra near the absorption edge. This relationship is subsequently employed to determine the lower bound to the Urbach frequency regime. Most interestingly, in this frequency interval, the optical absorption is Poisson distributed with very large statistical fluctuations. Finally, We determine the upper bound to the Urbach frequency regime by identifying the frequency at which transition to Poisson distribution takes place.Comment: 5 pages, 3 figure

Hydrosilylation of 1-alkenes with dichlorosilane

Symmetrically and unsymmetrically substituted diorganodichlorosilanes have been prepared by hydrosilylation with dichlorosilane using two different platinum catalysts, i.e., hexachloroplatinic acid (Speier's catalyst) and a platinum cyclovinylmethylsiloxane complex. Hydrosilylation of unsubstituted 1-alkenes proved to be very efficient, yielding anti-Markonikov substituted di-n-alkyldichlorosilanes. However, no reaction was observed when electron-deficient 1-alkenes were used. Octacarbonyldicobalt enabled formation of the monoadduct of 1H,1H,2H-perfluoro-1-hexene with dichlorosilane, which was employed in a second hydrosilylation of the olefin. Thus, the anti-Markovnikov diadduct was obtained in 40% overall yield. The two-step synthesis has also been applied successfully to obtain unsymmetrically substituted diorganodichlorosilanes containing nitrile and ether groups

Assessment of the suitability of composted sewage sludge as an adsorbent for the treatment of heavy-metal contaminated wastewater, with special reference to cadmium

Includes bibliography.A large proportion of sewage sludge in South Africa contains heavy metal concentrations which are deemed to be above threshold limits for its use as a fertiliser. Furthermore, sewage sludge has a high affinity for heavy metals. Until the sources of heavy metal contamination of municipal sewage sludge are considerably reduced the contaminated sewage sludge must either be disposed of or used for some other purpose. The use of contaminated sewage sludge as an adsorbent for treating heavy metal-contaminated wastewaters may provide an alternative and practical use for this material. The objective of this study was to assess the potential of composted sewage sludge (which is more stable and has a higher permeability than ordinary sewage sludge), produced from municipal sewage sludge in Milnerton, as an adsorbent for the extraction of heavy metals from contaminated wastewaters. The study was conducted with specific reference to cadmium since it is one of the most toxic of the heavy metals and occurs in many types of wastewaters