Information retrieval definition

Current chemical information systems offer three principal types of search facility. Structure search involves the search of a file of compounds for the presence or absence of a specified query compound, for example, to retrieve physicochemical data associated with a particular substance. Substructure search involves the search of a file of compounds for all molecules containing some specified query substructure of interest. Finally, similarity search involves the search of a file of compounds for those molecules that are most similar to an input query molecule, using some quantitative definition of structural similarity. 

Webster s definition for database is a large collection of data in a computer, organized so that it can be expanded, updated, and retrieved rapidly for various uses. An LC/MS database established for drug impurities contains multi-dimensional information such as relative retention times, UV spectra, molecular mass and substructural information. In order for the information to be updated and expanded, the methods used for information collection need to be unified. A generic LC/MS method allows relevant information to be collected in a consistent... 

As will become apparent in the later chapters, the statistical nature of the conclusions is such that the present amount of data in the crystallographic data base is inadequate. We find ourselves presenting results that show well-defined trends, but in doing so, have come to realize that we need a tenfold increase in the information from X-ray and neutron crystallography before the conclusions drawn can become really definitive. This tenfold increase in structural data will surely come within the next decade, and will be useful only if the publication, data storage, and retrieval mechanisms keep pace with the accelerating rate of data acquisition. 

This chapter has reviewed the basic principles of computer-aided drug design, and several strategies of how it can be successfully integrated with combinatorial chemistry to develop highly effective site-focused libraries. Diversity plays a key role, as the more diverse set of compounds tested that fit the site-focused criteria, the more information is retrieved to improve the site-focused definition, which further directs the search in diversity space. In addition, if good hits are found, the information can be fed back to find compounds close in diverse space to the hit. This new paradigm for structure-based combinatorial chemistry should provide a powerful tool for rapid discovery of novel, potent lead compounds in the years to come. 

It should be noted that there is no way to definitively discover whether information is retained for life or ever truly lost from memory. This is because even if someone cannot recall something that does not mean it is not present in memory. It may instead be inaccessible due to repression, interference, or retrieval failure. Moreover, it is often impossible to assess the accuracy of someone s individual memories as there are no available corroborative witnesses. 

Requirements for controls are based on definition of closed or open system. Under these definitions there isno direct correlation between, for example, using a publicphone line and an open system. Compliance with closed versus open standards is determined by how access rights to the data or documents are established and controlled by the owner(s) of this information. A system is defined as closed if access to the system containing the records or data is under the control of person(s) responsible for the content of the records or data in the system. A system is defined as open if access to the system is not under the control of the person(s) responsible for the content of the records therein. For example, dial-in retrieval over a public phone is closed where the records being accessed are under the control of the persons responsible for their content, whereas storage of records on a third party system is open because access to the records themselves is under the control of the third party. Sections 11.10 and 11.30 of the Final Rule list, respectively, the control measures required for establishing a closed or open system. 

What do we lose by failing to categorize the 332 items classified as other in Tables 3.3-3.6 Very little. Most of them are not story problems at all but have been erroneously placed with the story problems in the curricular materials. Instead of requiring the student to use his or her own prior knowledge about situations, they depend upon the student s ability to retrieve specific formulas (e.g., area, perimeter, volume) or to understand the mathematical definitions of specific terms (e.g., median, mode, probability). These terms are always used explicitly in the question directed to the student. It is clear from the wording of such problems that the situations (i.e., the stories) are relatively unimportant. On the other hand, for all cases in which the situation was important -because a problem solver must extract the meaning of the problem from the story situation and use that information to carry out necessary computations - the five situations served well. 

To achieve this SRS utilizes the special purpose programming language, ICARUS (Interpreter of Commands and Recursive Syntax), which is used both for the meta definition of biological resources and the syntactic description of the data in the resources. The SRS core includes programs which use ICARUS meta definitions and syntactic descriptions to index and retrieve information from resources. In the case of applications, the meta definition includes information on how to run the programs as well as the meta description of the syntax and structure of the output. 

In the preceding chapters we have seen how to define and describe the structure of a molecule or molecular fragment (Chapters 1 and 2), how to retrieve the relevant information from electronic databases (Chapter 3) and how to analyze this information with a variety of statistical methods (Chapter 4). Fragment definition, data retrieval and statistical analysis in structure correlation have their analogs in ordinary chemical experiments First a problem is identified, then the data are acquired from an appropriate experiment, filtered to distinguish the relevant from the irrelevant, and processed into a clear summary form. However, this is not the final step. The data still need to be understood. 

Another method which places most emphasis on the ability to retrieve homologous and analogous compounds is derived from an integrated system which uses a set of spectral features optimized to the specification given in Fig. 4. These features are coded in one bit each. To keep the information loss within acceptable limits, individual threshold levels are used for every feature. The definitions used are presented in Table 1. Different... 

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