Report on a visit to Tanzania, Kenya and Uganda. The Lake Victoria fishery and Tanzania fish kiln development

NRI has been involved in post-harvest research on the Lake Victoria Nile Perch fishery since 1987. Most of the work to date has focused on the development of a fuel efficient smoking kiln in Tanzania. This visit to Tanzania, Kenya and Uganda sought to investigate trends in the lake fishery, providing a context for future inputs on the kiln or in other areas

Useful Lessons from My Career as an Academic in Information Systems

This “last lecture” is to my fellow academics in information systems. My career spans the entire period of the adoption of information technology in organizations (from punched cards to the internet), the rise of the organization function of information systems, and the emergence of an academic field of IS (also called Management information Systems or MS). have had great opportunities to work with colleagues to: found an MS department, head an MS research center, create new S degrees and curricula, and write original books and manuals. I have been very involved with the Minnesota MS doctoral program as advisor to many doctoral students and on many dissertation committees. have been involved internationally and have been part of the leadership for our major S organizations. In my “last lecture” will address two topics. The first is how I see the future of our field. The second is some personal career advice for my younger colleagues. I have had many successes and some failures, and have observed the careers of many faculty members and doctoral students. I will summarize my observations as actionable advice about being a successful academic while being a happy, contributing human being

Binding of Tn3 Resolvase to Its Resolution Site

Tn3 resolvase binds to three subsites within its DNA target, res. Complexes of resolvase bound to res can be isolated using non-denaturing polyacrylamide electrophoresis (PAGE). Six complexes are generated with Tn3 res and resolvase, but only three complexes have been reported for the related gammadelta resolution system. By varying the conditions used for non-denaturing PAGE it was demonstrated that the different methods used were not solely responsible for the observed differences in the patterns of complexes produced. In vivo overexpression of Tn3 resolvase in the presence of several tritiated amino acids was used to produce tritiated resolvase. Substantial purification of the radiolabelled resolvase was achieved using a method adapted for use with small amounts of material, but based on a previously published resolvase purification method. The 3H-resolvase sample produced was used, with 32P end-labelled DNA fragments, to determine the relative and absolute stoichiometry of the protein/DNA complexes observed for Tn3. Although with res one complex (complex 5) was not isolated, the observed results indicate that the stoichiometry of the least retarded complex (complex 1) is one resolvase monomer per res site, and that this value increases by one monomer per res for each successively more retarded complex, to a value of six resolvase monomers per res site for the most retarded complex (complex 6). This is consistent with the prediction that each subsite of res can be bound by a dimer of resolvase. A synthetic DNA was used to generate subsite II in isolation from subsites I and III. Binding of Tn3 resolvase to subsite II produced two (or sometimes three) complexes. The stoichiometry of complexes of subsite II with resolvase was consistent with results produced for res, i.e. the first complex had a ratio of one monomer of resolvase per DNA site and this value increased by one monomer per site for successively more retarded complexes. Synthetic derivatives of a subsite II sequence were also produced, with an additional 5 or 10 base pairs (bp) of DNA sequence inserted at the subsite centre (named subsite (II + 5) and subsite (II + 10), respectively). Tn3 resolvase was shown to bind to these altered subsites, but the distribution of complexes produced was different from those for subsite II. Complexes of subsite (II + 10) had the same stoichiometry as equivalent complexes of subsite II, as did the first two complexes of subsite (II + 5). DNase I footprinting and methylation interference analysis of Tn3 resolvase binding to subsites II, (II + 5) and (11 + 10) suggested that the protein/DNA contacts made were equivalent to those made by resolvase binding to a normal subsite within res. Hence it was concluded that the differences in complex formation observed with subsites (II + 5) and (II + 10) are likely to result from an alteration of contacts made between resolvase molecules bound at these sites. Binding analysis of several different DNA fragments carrying subsite II or subsite (II + 10) was used to show that binding of a monomer or a dimer of Tn3 resolvase induces a bend at the centre of each subsite. From previous studies it seems likely that resolvase monomer-induced bending of DNA is a common feature for binding to each subsite of res. Purified samples of gammadelta resolvase and of a gammadelta resolvase mutant, gammadelta M106C, (both supplied by Nigel Grindley) were also used in binding experiments. The amino acid substitution present in gammadelta M106C allows the formation of covalently linked dimers of resolvase. Comparison of binding of Tn3, gammadelta and gammadelta M106C resol vases to subsites II, (II + 5) and (II + 10) showed that gammadelta resolvase binds as a predominantly dimeric species, and that Tn3 resolvase binds as a predominantly monomeric species. This comparison also suggested that binding of Tn3 resolvase to subsite II is co-operative. A model of Tn3 resolvase binding to res, based on these results, is proposed, in which the majority of resolvase is monomeric and occupies the res site in six successive steps, each representing binding of a resolvase monomer to one half of a subsite, until each subsite is bound by a dimer of resolvase. The subsites are not occupied in only one specific order, but in a variable order, probably reflecting the affinity of resolvase for each target site. It seems likely that resolvase bound to one half of a subsite can 'shuffle' between binding positions of res during non-denaturing PAGE, without complete dissociation of the retarded complex. A mutagenesis strategy was developed for the production and isolation of mutants of Tn3 resolvase capable of directing resolution between isolated subsite I elements. Initial attempts to produce such mutants were unsuccessful. A new vector for mutagenesis and expression of resolvase was produced and the resolution substrates, used to screen for mutants, were improved

Body size, sex and high philopatry influence the use of agricultural land by Galapagos giant tortoises

As agricultural areas expand, interactions between wild animals and farmland are increasing. Understanding the nature of such interactions is vital to inform the management of human-wildlife coexistence. We investigated patterns of space use of two Critically Endangered Galapagos tortoise species, Chelonoidis porteri and Chelonoidis donfaustoi, on privately owned and agricultural land (hereafter farms) on Santa Cruz Island, where a human-wildlife conflict is emerging. We used GPS data from 45 tortoises tracked for up to 9 years, and data on farm characteristics, to identify factors that influence tortoise movement and habitat use in the agricultural zone. Sixty-nine per cent of tagged tortoises used the agricultural zone, where they remained for a mean of 150 days before returning to the national park. Large male tortoises were more likely to use farms for longer periods than female and smaller individuals. Tortoises were philopatric (mean overlap of farmland visits = 88.7 ± SE 2.9%), on average visiting four farms and occupying a mean seasonal range of 2.9 ± SE 0.3 ha. We discuss the characteristics of farm use by tortoises, and its implications for tortoise conservation and coexistence with people

A rational approach to heavy-atom derivative screening

In order to overcome the difficulties associated with the ‘classical’ heavy-atom derivatization procedure, an attempt has been made to develop a rational crystal-free heavy-atom-derivative screening method and a quick-soak derivatization procedure which allows heavy-atom compound identification

Role of Integrin Expression in Adenovirus-Mediated Gene Delivery to the Intestinal Epithelium

Overview summary Previous studies of adenovirus-mediated gene transfer of the interleukin-1 receptor antagonist protein to rat jejunum have produced limited gene expression. In the present study, we have shown that integrins play a significant role in efficient adenoviral infection of the intestinal epithelium. As enterocytes differentiate, integrin expression decreases. This coincides with significant reduction in adenoviral transduction efficiency. Results from two in vitro models of the intestinal epithelium (Caco-2 and IEC-18 cells) show that αvβ3 integrins have the most influence on adenoviral internalization. Results from screening of rat intestinal segments for expression of the αvβ5 integrin suggest that, based on integrin expression, the ileum is a prime target for efficient adenovirus-mediated gene transfer. We have also found that administration of immunomodulating agents and inflammatory disease states provide a favorable environment for efficient internalization of adenoviral vectors due to up-regulation of integrin receptors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63160/1/hum.1998.9.4-561.pd

Formal Availability Analysis using Theorem Proving

Availability analysis is used to assess the possible failures and their restoration process for a given system. This analysis involves the calculation of instantaneous and steady-state availabilities of the individual system components and the usage of this information along with the commonly used availability modeling techniques, such as Availability Block Diagrams (ABD) and Fault Trees (FTs) to determine the system-level availability. Traditionally, availability analyses are conducted using paper-and-pencil methods and simulation tools but they cannot ascertain absolute correctness due to their inaccuracy limitations. As a complementary approach, we propose to use the higher-order-logic theorem prover HOL4 to conduct the availability analysis of safety-critical systems. For this purpose, we present a higher-order-logic formalization of instantaneous and steady-state availability, ABD configurations and generic unavailability FT gates. For illustration purposes, these formalizations are utilized to conduct formal availability analysis of a satellite solar array, which is used as the main source of power for the Dong Fang Hong-3 (DFH-3) satellite.Comment: 16 pages. arXiv admin note: text overlap with arXiv:1505.0264

New minimal weight representations for left-to-right window methods

Abstract. For an integer w ≥ 2, a radix 2 representation is called a width-w nonadjacent form (w-NAF, for short) if each nonzero digit is an odd integer with absolute value less than 2 w−1, and of any w consecutive digits, at most one is nonzero. In elliptic curve cryptography, the w-NAF window method is used to efficiently compute nP where n is an integer and P is an elliptic curve point. We introduce a new family of radix 2 representations which use the same digits as the w-NAF but have the advantage that they result in a window method which uses less memory. This memory savings results from the fact that these new representations can be deduced using a very simple left-to-right algorithm. Further, we show that like the w-NAF, these new representations have a minimal number of nonzero digits. 1 Window Methods An operation fundamental to elliptic curve cryptography is scalar multiplication; that is, computing nP for an integer, n, and an elliptic curve point, P. A number of different algorithms have been proposed to perform this operation efficiently (see Ch. 3 of [4] for a recent survey). A variety of these algorithms, known as window methods, use the approach described in Algorithm 1.1. For example, suppose D = {0, 1, 3, 5, 7}. Using this digit set, Algorithm 1.1 first computes and stores P, 3P, 5P and 7P. After a D-radix 2 representation of n is computed its digits are read from left to right by the “for ” loop and nP is computed using doubling and addition operations (and no subtractions). One way to compute a D-radix 2 representation of n is to slide a 3-digit window from right to left across the {0, 1}-radix 2 representation of n (see Section 4). Using negative digits takes advantage of the fact that subtracting an elliptic curve point can be done just as efficiently as adding it. Suppose now that D