Efficient database access from Prolog

In designing the interface between a relational database and a Prolog interpreter, efficiency is a major issue. The authors present a method for loading into the memory-resident database of Prolog facts permanently stored in secondary storage. The rationale of the method is to save access to the database by never repeating the same query and by storing in main memory, in a compact and efficient way, information about the past interaction with the database. The authors discuss how to reduce subsumption rests required by the method to pattern matching in many relevant cases. They also describe a simulator of the method, which validates their approach, and they discuss the results of the simulation     

Scattering of electromagnetic waves from moving surfaces

Electromagnetic wave scattering from moving objects is considered. Use is made of the reformulated current method in which the object is replaced by a current distribution radiating into an unbounded media. Cylindrical and spherical profiles in nondeterministic motion are considered. Results are obtained for far-field and steady-state cases when the radii of curvature are large compared to the wavelength.     

Conceptual modeling of data-intensive Web applications

Many of the Web applications around us are data-intensive; their main purpose is to present a large amount of data to their users. Most online trading and e-commerce sites fall into this category, as do digital libraries and institutional sites describing private and public organizations. Several commercial Web development systems aid rapid creation of data-intensive applications by supporting semiautomatic data resource publishing. Automatic publishing is typically subject to the constraints of database schemas, which limit an application designer's choices. Thus, Web application development often requires adaptation through programming, and programs end up intricately mixing data, navigation, and presentation semantics. Presentation is often a facade for elements of structure, composition, and navigation. Despite this frequently unstructured development process, data-intensive applications, based on large data sets organized within a repository or database, generally follow some typical patterns and rules. We describe these patterns and rules using WebML as a conceptual tool to make such notions explicit. WebML is a conceptual Web modeling language that uses the entity-relationship (ER) model for describing data structures and an original, high-level notation for representing Web content composition and navigation in hypertext form.     

Mashing Up Search Services

Mashup languages offer new graphic interfaces for service composition. Normally, composition is limited to simple services, such as RSS or Atom feeds, but users can potentially use visual mashup languages for complex service compositions, with typed parameters and well-defined I/O interfaces. Composing search services introduces new issues, however, such as determining the optimal sequence of search invocations and separately composing ranked entries into a globally ranked result. Enabling end users to mash up services through suitable abstractions and tools is a viable option for improving service-based computations.     

Active rules for XML: A new paradigm for E-services

XML is rapidly becoming one of the most widely adopted technologies for information exchange and representation. As the use of XML becomes more widespread, we foresee the development of active XML rules, i.e., rules explicitly designed for the management of XML information. In particular, we argue that active rules for XML offer a natural paradigm for the rapid development of innovative e-services. In the paper, we show how active rules can be specified in the context of XSLT, a pattern-based language for publishing XML documents (promoted by the W3C) which is receiving strong commercial support, and Lorel, a query language for XML documents that is quite popular in the research world. We demonstrate, through simple examples of active rules for XSLT and Lorel, that active rules can be effective for the implementation of e-commerce services. We also discuss the various issues that need to be considered in adapting the notion of relational triggers to the XML context. Received: 30 October 2000 / Accepted: 19 December 2000 Published online: 27 April 2001     

communis0Agricultural Sci

TPase Activity of Microsomal Membrane and Lipid Peroxidation in Harvested Peach FruitThe Relations     

Populations of the Gall Midge Dasineura oxycoccana on Cranberry and Blueberry Produce and Respond to Different Sex Pheromones

We identified and field-tested the sex pheromones of Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae) midges collected from cranberry, Vaccinium macrocarpon Aiton, and from highbush blueberry, Vaccinium corymbosum L., commonly named cranberry tipworm (CTW) and blueberry gall midge (BGM), respectively. Coupled gas chromatographic-electroantennographic detection (GC-EAD) analyses of pheromone gland extract from the ovipositor of calling CTW females revealed one component (<10 pg per ovipositor/pheromone gland) that elicited antennal responses from CTW males. Stepwise identification was based on its mass spectrum in a concentrated sample with 300 pheromone gland equivalents, retention indices (RI) on three GC columns (DB-5, DB-23, and DB 210), RI inter-column differentials, and RIs and double bond positions of other midge pheromones. These analyses indicated that (8Z)-2,14-diacetoxy-8-heptadecene (2,14-8Z-17) was the candidate pheromone of the CTW. GC-EAD analysis of pheromone gland extract from calling BGM females revealed two components that elicited antennal responses from BGM males. Retention times on the three GC columns were consistent with 2,14-8Z-17 and 2,14-17, indicating that these were candidate pheromone components of the BGM. The four stereoisomers of 2,14-8Z-17 were stereoselectively synthesized and field-tested in cranberry. Delta-type traps baited with SS-2,14-8Z-17 captured significantly more CTW males than did traps baited with any other single stereoisomer or with all four stereoisomers combined. In blueberry, delta-type traps baited with RR-2,14-8Z-17 captured significantly more BGM males than did traps baited with any other single stereoisomer or with all four stereoisomers combined. Subsequent field experiments demonstrated that RR-2,14-17 is the major pheromone component of BGM, and that RR-2,14-8Z-17 is a pheromone component that does not enhance attractiveness of RR-2,14-17. The BGM pheromone RR-2,14-17 has no antagonistic effect on the CTW pheromone SS-2,14-8Z-17 and vice versa. Our results substantiate the conclusion that populations of D. oxycoccana on cranberry and blueberry represent two cryptic species.     

An 11.1 mW 42 MS/s 10 b ADC With Two-Step Settling in 0.18 m CMOS

A pipelined analog-to-digital converter (ADC) uses switched-capacitor stages that settle in two steps that occur sequentially in time. The first step of settling places charge onto the load capacitance using charge pumps, and the second fulfills the settling requirements using typical negative feedback around an operational amplifier. Hence, the design combines the efficiency of a fast charge-transfer phase with the gain and noise-immunity advantages of amplifier-driven settling. Improved conversion efficiency results from a higher ratio of current delivered to the load to that consumed in static biasing. Additional circuitry constrains critical amplifier node voltages during the charge transfer, facilitating a graceful transition to amplifier-driven settling. The two-step settling technique is demonstrated in a 2.5 bit/stage 10-bit pipelined ADC that consumes 11.1 mW while sampling a 21.3 MHz input signal at 42 MS/s. The resulting SNDR is 55.6 dB $rm (ENOB = 8.94)$ and the SFDR is 67.5 dB.      

Good segregation,bad segregation

Much of the literature on segregation is underlain by an implicit model which argues that groups start highly segregated in inner city locations and disperse over time. Parallel and related to this spatial pattern is the social process of assimilation. Groups start highly segregated and unassimilated and become dispersed and assimilated over time. The paper argues that there is a critical distinction between the black American ghetto and other forms of segregation. The ghetto is not part of a continuum of spatial distributions which begins in the inner city and ends in the suburbs three generations later; it is an end in itself. The black ghetto is different in kind from other forms of segregation. Nearly all of its members are black and nearly all the black population in American cities is in such locations. African American segregation has been almost continuously high during the twentieth century and has not diminished with socio-economic improvement. Ethnic enclaves of the Irish, Poles or other ethnicities in the USA never achieved such homogeneous concentrations. Thus representing European concentrations as having evolved from a past distribution, which was akin to the present black ghetto, falsifies the European past and mistakes the current dilute levels of European concentration as representing the black future. On the other hand, the equation of spatial segregation with levels of social assimilation, is largely supported. The process of assimilation, like the sequence of spatial segregation, is neither inevitable nor unidirectional.