Two Types of Planning in Neighborhoods

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68338/2/10.1177_0739456X8400300209.pd

Patterns of antigenic diversity and the mechanisms that maintain them

Many of the remaining challenges in infectious disease control involve pathogens that fail to elicit long-lasting immunity in their hosts. Antigenic variation is a common reason for this failure and a contributor to the complexity of vaccine design. Diversifying selection by the host immune system is commonly, and often correctly, invoked to explain antigenic variability in pathogens. However, there is a wide variety of patterns of antigenic variation across space and time, and within and between hosts, and we do not yet understand the determinants of these different patterns. This review describes five such patterns, taking as examples two bacteria (Streptococcus pneumoniae and Neisseria meningitidis), two viruses (influenza A and HIV-1), as well as the pathogens (taken as a group) for which antigenic variation is negligible. Pathogen-specific explanations for these patterns of diversity are critically evaluated, and the patterns are compared against predictions of theoretical models for antigenic diversity. Major remaining challenges are highlighted, including the identification of key protective antigens in bacteria, the design of vaccines to combat antigenic variability for viruses and the development of more systematic explanations for patterns of antigenic variation

The use of a scanning electrochemicl impedance spectroscopy technique to investigate localized corrosion

Recently, the authors have proposed a method for generating local electrochemical impedance maps of electrodes. In this technique impedance maps, at each frequency of interest, are generated by measuring the ratio of ac solution current density, very near the electrode, to the applied potential is measured as a function of position. A review of this method, the results from two model systems, which demonstrate that this technique may be used to generate quantitative data, and its use to investigate aluminum alloys will be presented. 7 refs., 3 figs

An experiment to observe strange particle production in ion collisions at the AGS

We present the results of a measurement of neutral vee production with 14.6 {times} A GeV/c Si beams on Au and Cu targets. The {Lambda} and K{sub s}{sup 0} yields were measured as a function of negative particle multiplicity. Effective temperatures were determined from an exponential fit to the transverse mass distribution. 6 refs., 8 figs., 1 tab