Biofuels: Potentials, Problems & Solutions

Biofuels have the exciting potential of mitigating the grave threats of global warming, reducing the world\u27s dependence on imported oil from insecure sources and of reducing the skyrocketing costs of oil that are threatening to undermine the world\u27s economies and devastating the people in non-oil producing, developing countries. For the people in these countries, biofuel offer a promising road to enhance development since they use local materials, can provide local jobs, and do not require the import of expensive equipment and expertise. Brazil has been the pioneer in the use of biofuel, allowing it to eliminate its oil imports, becoming completely energy independent, and demonstrating to the world the potential benefits of substitution of biofuels for fossil fuels. Indeed, inspired by Brazil\u27s example, the United States in recent years has developed a strong biofuel industry, albeit from the disadvantageous feedstock of corn. The United States has just created an alliance with Brazil to make major purchases of its biofuels. The European Union and countries around the world are rapidly developing their own biofuel potentials. But Brazil and its replicators have to exercise great care in designing and implementing biofuel programs. The environmental and social risks of biofuel development, also demonstrated in Brazil, are great and could well undermine all of the potential advantages if not done right

Silent Spring - the lost call

The "silence" in Rachel Carson's Silent Spring1 alludes to the demise of bird populations through reproductive problems and death resulting from exposure to the pesticides of that time, many of which are endocrine active. Endocrine disrupting chemicals (EDCs) are compounds which may interfere with the endocrine system, producing effects that may disrupt the physiologic function of hormones. Early research on EDC exposure in humans and wildlife has focused mainly on reproductive effects of estrogenic chemicals, however recent studies have revealed that effects of estrogenic as well as non-estrogen active chemicals are often more far reaching than the reproductive system, and even mild exposures experienced early in development may have detrimental effects that are maintained throughout adulthood. Here we show trenbolone acetate, an androgen active environmental contaminant used as a growth promoter for cattle, to cause a literal silence in Japanese quail (Coturnix japonica) chicks following a one time embryonic exposure. Vocalizations were not merely lessened; this is the first study to demonstrate an environmental contaminant to cause a complete abolishment of the ability to vocalize. Since many reasons for vocalization in birds are directly linked to survival of the individual and species, the potential for detrimental population effects is a grave possibility for many avian species that may encounter androgen active chemicals in the environment. Many androgen active EDCs are persistent and ubiquitous in distribution, thereforechances for exposure to these chemicals in birds may be high. We hope that powerful, yet subtle effects like the ones presented here will encourage further research with EDCs to expand beyond the traditional focus of reproductive effects of estrogenic chemicals

USGS/NOAA Workshop on Mycobacteriosis in Striped Bass, May 7-10, 2006, Annapolis, Maryland

As a Federal trust species, the well-being of the striped bass (Morone saxatilis) population along the Eastern Seaboard is of major concern to resource users. Striped bass are an extremely valuable commercial and recreational resource. As a principal piscivore in Chesapeake Bay, striped bass directly or indirectly interact with multiple trophic levels within the ecosystem and are therefore very sensitive to biotic and abiotic ecosystem changes. For reasons that have yet to be defined, the species has a high intrinsic susceptibility to mycobacteriosis. This disease has been impacting Chesapeake Bay striped bass since at least the 1980s as indicated by archived tissue samples. However, it was not until heightened incidences of fish with skin lesions in the Pocomoke River and other tributaries of the Chesapeake Bay were reported in the summer and fall of 1996 and 1997 that a great deal of public and scientific interest was stimulated about concerns for fish disease in the Bay. (PDF contains 50 pages

The Decline of Indian Tribal Sovereignty in the Nineteenth Century

The artificial air of the Nineteenth Century was filled with such pious asininities as the white man\u27s burden and saving the heathen form hell . To our cynical generation this jargon of concealed desires seems the ultimate in hypocrisy but it should be remembered that such an attitude was not an isolated phenomenon; it was merely one of the high points in an imperialism which is as old as modern civilization. Conquest is almost synonymous with man who, motivated by the conflict between inertia and the necessity of existence, will whenever possible force some weaker people to do his work and take their possessions. However, since the conqueror may be threatened by a later comer he usually cloaks his economic motives with sanctimonious expressions of morality and justice. The capacity of the human mind to fool itself is infinite

Strengthening of the Resource Conservation and Recovery Act in 1984: The Original Loopholes, the Amendments, and the Political Factors Behind Their Passage

This commentary discusses the nature of the legal loopholes that existed in the original RCRA statute, and highlights several of the provisions of the 1984 RCRA amendments that serve to either rectify or ameliorate the prior deficiencies. It also examines the political factors that affected the passage of the 1984 amendments, enabling them to pass during a period of anti-regulatory emphasis

Mathematical conjecturing and proving

Most university courses in mathematics programs are characterized by a strong focus on the axiomatic nature of mathematics, and thus also on proof as the central scientific method of mathematics (Selden, A. & Selden, 2008). Lecturers write proofs on the blackboard, students attempt to demonstrate their understanding and skills by proving theorems on their own or in collaboration with others. However, there is often little systematic discussion in these courses on how new mathematical conjectures can be generated and on how proofs are constructed (Alcock, 2010). Students’ experiences with conjecturing and proving in schools or in university mathematics courses often lead them to “consider proof as a static product rather than a negotiated process that can help students justify and make sense of mathematical ideas” (Otten, Bleiler-Baxter, & Engledowl, 2017, p. 112). Yet, several authors (e.g., Epp, 2003; Savic, 2015a; Selden, A. & Selden, 2008) have hypothesized that often only little time can be devoted to illustrate students which strategies and processes may help to step through the proof construction process and to recover from proving impasses. Furthermore, the knowledge about what characterizes proof processes that lead to a successful outcome (i.e., an acceptable mathematical proof [according to local acceptance criteria]) is rare. To approach this issue, an extensive systematic literature search was conducted to summarize common claims and empirical findings about promising conjecturing and proving processes. 126 articles that focussed on conjecturing and proving were clustered using a topic modeling method. The algorithm identified 17 different topics. The most representative papers for each topic, in total 45 papers, were qualitatively analysed with regard to their research perspectives on which they were based and their claims and findings about the processes that are needed to successfully generate conjectures and construct proofs. This combination of statistical clustering and qualitative analyses allowed a systematic categorization of claims and empirical findings about successful conjecturing and proving processes in the literature. Based on this review, a set of characteristics of conjecturing and proving processes, that are assumed or reported to be crucial for success, is proposed. For the further analysis of such process characteristics, we started from a model differentiating students’ prerequisites they bring to bear on the proving situation, the conjecturing and proving processes they engage in, and the quality of the resulting product. The main question of the empirical work in this dissertation was, which process characteristics influence the quality of the final product (the formulated conjecture and constructed proof), and in which way they mediate the impact of students’ prerequisites on this product. Specifically, we distinguished between individual-mathematical and social-discursive process characteristics of conjecturing and proving. These process characteristics were extracted from prior research in mathematics education or in educational psychology or in the Learning Sciences. The central aim of this dissertation was to develop an instrument for assessing (prospective undergraduate) mathematics students’ conjecturing and proving processes in collaborative situations. A high-inference rating scheme with seven scales, based on theoretical considerations and on rating guidelines adapted from educational research was designed. The rating scheme was evaluated in a study with N=98 prospective undergraduate students working in dyads on an open-ended conjecturing and proving task. The results of the empirical study with regard to the basic analyses showed that collaborative conjecturing and proving processes could be rated with sufficient reliability and that the structure of the data corresponded to the underlying theoretical assumption that two dimensions, one related to individual-mathematical and one related to social-discursive process characteristics can be distinguished. The in-depth analyses pointed out that individual-mathematical process characteristics were predictive for the quality of the resulting product and mediated the relation between prerequisites (students’ prior knowledge on proof) and the quality of the product. In this way, the dissertation contributes to the scientific debate on how to assess (mathematical argumentation) skills (e.g., Blömeke, Gustafsson, & Shavelson, 2015; Koeppen, Hartig, Klieme, & Leutner, 2008) and provides theoretical and empirical insights on individual-mathematical and social-discursive process characteristics that describe the quality of collaborative conjecturing and proving processes

Studying the Lysine Acetylation of Aconitase Isozymes in E. coli

The contents of this thesis have been modified from the publication “Araujo J, Ottinger S, Venkat S, Gan Q and Fan C (2022) Studying Acetylation of Aconitase Isozymes by Genetic Code Expansion. Front. Chem. 10:862483”. Though studies have found multiple lysine sites in which acetylation takes place in Escherichia Coli aconitase, acetylation’s effects on the enzyme’s activity have yet to be studied. Aconitase is the dehydratase-hydratase found in the citric acid and glyoxylate cycles responsible for the reversible isomerization of citrate to isocitrate via cis-aconitate intermediate. There are two isoforms of aconitase in E. coli: AcnA and AcnB. In this study, the genetic code expansion technique was utilized to generate 14 different site-specifically acetylated aconitases, with both isozymes being represented. Following enzyme assays and kinetic analysis of the variants, it was found that the acetylation of two altered aconitases impacted the level of enzyme kinetics from that of their wild-type counterparts, with AcnA K684 decreasing enzyme activity and AcnB K567 increasing enzyme activity