Genetic Toolkit for Assessment and Prediction of Population-Level Impacts of Bridge Construction on Birds

Recent studies have highlighted alarming rates of declines in bird populations across the country. The State of California is home to over 650 resident and migrant avian species. Legislation for protecting these species has existed for over a century now, yet tools for identifying populations and understanding seasonal movement remain limited. Recently, genetic and genomic tools have provided a method for understanding population structure, allowing for more informed delineation of management units. The goal of this project was to create a genetic toolkit for identifying breeding populations and assigning individuals to those populations. Ultimately, such tools could be used to assess population-level impacts when there are conflicts with birds at infrastructure construction sites. As a test case, we sequenced entire genomes for 40 individual Anna’s hummingbirds (Calypte anna) from across the state. Based on this initial data, we found low levels of differentiation between sampled locations, suggesting that C. anna in California are not subdivided into different population units. However, there was a weak signal of geography suggesting there may be localized genetic differences in a small proportion of the genome. Follow-up work will focus on a broader sampling across the state of California to clarify any possible population subdivision or geographical patterns of differentiation.View the NCST Project Webpag

Reductive cleavage of sulfones and sulfonamides by neutral organic super electron-donor (S.E.D.) reagent

The sulfonyl group finds extensive applications in organic and medicinal chemistry both in sulfonamides, popular as robust protecting groups for amines, and in sulfones. Frequently, sulfones are introduced into synthetic schemes to assist particular transformations; further progress along the synthetic route can later require the removal of a sulfone group, and this can be achieved by reductive desulfonylation or, in the special cases of α-halo- or ß-acyloxysulfones, by elimination to an alkene

A palace fit for the future: Desirability in temporal work

Research on the strategic organization of time often assumes that collective efforts are motivated by and oriented toward achieving desirable, although not necessarily well-defined, future states. In situations surrounded by uncertainty where work has to proceed urgently to avoid an impending disaster, however, temporal work is guided by engaging with both desirable and undesirable future outcomes. Drawing on a real-time, in-depth study of the inception of the Restoration and Renewal program of the Palace of Westminster, we investigate how organizational actors develop a strategy for an uncertain and highly contested future while safeguarding ongoing operations in the present and preserving the heritage of the past. Anticipation of undesirable future events played a crucial role in mobilizing collective efforts to move forward. We develop a model of future desirability in temporal work to identify how actors construct, link, and navigate interpretations of desirable and undesirable futures in their attempts to create a viable path of action. By conceptualizing temporal work based on the phenomenological quality of the future, we advance understanding of the strategic organization of time in pluralistic contexts characterized by uncertainty and urgency

Influence of solvent in controlling peptide−surface interactions

Protein binding to surfaces is an important phenomenon in biology and in modern technological applications. Extensive experimental and theoretical research has been focused in recent years on revealing the factors that govern binding affinity to surfaces. Theoretical studies mainly focus on examining the contribution of the individual amino acids or, alternatively, the binding potential energies of the full peptide, which are unable to capture entropic contributions and neglect the dynamic nature of the system. We present here a methodology that involves the combination of nonequilibrium dynamics simulations with strategic mutation of polar residues to reveal the different factors governing the binding free energy of a peptide to a surface. Using a gold-binding peptide as an example, we show that relative binding free energies are a consequence of the balance between strong interactions of the peptide with the surface and the ability for the bulk solvent to stabilize the peptide

Social impact management through planning and development : Hedonic Psychology and a new approach to tourism in Zanzibar

Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2004.Includes bibliographical references (p. 127-130).This study proposes a new approach to tourism planning and development based on three threads in the literature on social impact management: (1) the current approach to tourism studies; (2) the writings and activities of the Aga Khan Trust for Culture; and, (3) the emerging field of Hedonic Psychology. Combining the best efforts of each of these fields -- respectively, understanding the tensions that arise in tourist areas, developing real-world projects, and understanding the psychological drivers of wellbeing -- creates this new approach, which I call the "Hedonic Psychology Approach." To illustrate the application or this approach and to expose the process of planning and development according to this approach, salient features of the Stone Town of Zanzibar are presented, including brief descriptions of the spatial, social, political, and economic conditions of the historic area. Several recommendations are proposed, from improving open space design to maximize interactions among people, to increasing the coordination new development to institutionalize the potential benefits of the new approach.by A. Tell Metzger.M.C.P

Computational study on the boundary between the concerted and stepwise mechanism of bimolecular SNAr reactions

The text-book mechanism of bimolecular nucleophilic aromatic substitutions (SNAr) reactions is a stepwise process that proceeds via a so-called Meisenheimer intermediate. Only recently the alternative, concerted version of this mechanism has gained acceptance as more and more examples thereof have been reported. But so far only isolated examples of concerted SNAr reactions have been described and a coherent picture of when a SNAr reaction proceeds via a stepwise and when via a concerted mechanism has not yet been established. Here key factors are identified that influence the mechanistic choice of SNAr reactions. Moreover, the electron affinity is used as a simple descriptor to make a prediction on whether a given aryl fluoride substrate favors a concerted or stepwise mechanism

Predicting the reducing power of organic super electron donors

The utilization of computational methods to predict reactivity is an increasingly useful tool for chemists to save time and materials by screening compounds for desirable reactivity prior to testing in the laboratory. In the field of electron transfer reactions, screening can be performed through the application of Marcus Hush theory to calculate the activation free energy of any potential reaction. This work describes the most accurate and efficient approach for modelling the electron transfer process. In particular, the importance of using an electron transfer complex to model these reactions rather than considering donor and acceptor molecules as separate entities is highlighted. The use of the complex model is found to produce more accurate calculation of the electron transfer energy when the donor and acceptor spin densities are adequately localised