Quotient Complexity of Regular Languages

The past research on the state complexity of operations on regular languages is examined, and a new approach based on an old method (derivatives of regular expressions) is presented. Since state complexity is a property of a language, it is appropriate to define it in formal-language terms as the number of distinct quotients of the language, and to call it "quotient complexity". The problem of finding the quotient complexity of a language f(K,L) is considered, where K and L are regular languages and f is a regular operation, for example, union or concatenation. Since quotients can be represented by derivatives, one can find a formula for the typical quotient of f(K,L) in terms of the quotients of K and L. To obtain an upper bound on the number of quotients of f(K,L) all one has to do is count how many such quotients are possible, and this makes automaton constructions unnecessary. The advantages of this point of view are illustrated by many examples. Moreover, new general observations are presented to help in the estimation of the upper bounds on quotient complexity of regular operations

Sí Se Puede: Using Participatory Research to Promote Environmental Justice in a Latino Community in San Diego, California

Community-based participatory research (CBPR) increasingly is seen as a potent tool for studying and addressing urban environmental health problems by linking place-based work with efforts to help effect policy-level change. This paper explores a successful CBPR and organizing effort, the Toxic Free Neighborhoods Campaign, in Old Town National City (OTNC), CA, United States, and its contributions to both local policy outcomes and changes in the broader policy environment, laying the groundwork for a Specific Plan to address a host of interlocking community concerns. After briefly describing the broader research of which the OTNC case study was a part, we provide background on the Environmental Health Coalition (EHC) partnership and the setting in which it took place, including the problems posed for residents in this light industrial/residential neighborhood. EHC’s strong in-house research, and its training and active engagement of promotoras de salud (lay health promoters) as co-researchers and policy change advocates, are described. We explore in particular the translation of research findings as part of a policy advocacy campaign, interweaving challenges faced and success factors and multi-level outcomes to which these efforts contributed. The EHC partnership's experience then is compared with that of other policy-focused CBPR efforts in urban environmental health, emphasizing common success factors and challenges faced, as these may assist other partnerships wishing to pursue CBPR in urban communities

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts. June 4-7, 2019, Szczyrk, Polan

Guest Editorial: Ships, Trucks, and Trains: Effects of Goods Movement on Environmental Health-0

<p><b>Copyright information:</b></p><p>Taken from "Guest Editorial: Ships, Trucks, and Trains: Effects of Goods Movement on Environmental Health"</p><p>Environmental Health Perspectives 2006;114(4):A204-A205.</p><p>Published online Jan 2006</p><p>PMCID:PMC1440794.</p><p>This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose.</p