General Classification Scheme Research Articles

‘A Rustic in the Library ’. The First Dr Pafford Memorial Lecture

Argues that the elements that comprise ‘style’ in creative writing are directly applicable to librarians, in the choice of books and periodicals, and in the process of cataloguing and classification to make them accessible to users. By the selection and arrangement of their stock librarians reveal professional accounts of the culture they have inherited and are endeavouring to pass on to future generations. Illustrates the discussion with particular reference to the life and career of Dr John Henry Pyle Pafford, Librarian at London University, and in particular to his views on the development of general classification schemes, such as the Dewey Decimal Classification and Bliss Classification, and the work of the Classification Research Group. Concludes by noting his work in the fields of education, national and international library co-operation, and as Library-Keeper of the University.

Tool agents in coordinated information systems

We present a general agent-based architecture for coordinating the operation of autonomous tools based on a two-level repository scheme. Our architecture comprises two forms of agents — coordination agents which are responsible for the coordination activity and tool agents which are responsible for monitoring and controlling tool operations. The agents cooperate to ensure the overall consistency of information. In particular, we focus here on the tool agents and describe in detail the design and development of agents which enable existing tools to be integrated into such a coordination system. We present a general tool agent architecture and tool classification scheme. To demonstrate the issues and approaches, we describe two specific tool agents in some detail — one for a revision control system and one for a CAD system.

Dewey for Windows

The Dewey Decimal Classification (DDC) is the leading general classification scheme for libraries and it is now increasingly being used for electronic resources, both as standalone products and on the Internet. It is therefore to be expected that it should itself be available in electronic form and this CD provides it, with flexible and powerful tools for finding and building numbers.

Reflection symmetric ballistic microstructures: Quantum transport properties.

We show that reflection symmetry has a strong influence on quantum transport properties. Using a random S-matrix theory approach, we derive the weak-localization correction, the magnitude of the conductance fluctuations, and the distribution of the conductance for three classes of reflection symmetry relevant for experimental ballistic microstructures. The S-matrix ensembles used fall within the general classification scheme introduced by Dyson, but because the conductance couples blocks of the S-matrix of different parity, the resulting conductance properties are highly non-trivial.

On the propagation of the kurtosis parameter of general beams

The behaviour of the kurtosis parameter of a partially coherent beam that freely propagates is investigated. A general classification scheme of light beams is given in terms of the number of extremals of the kurtosis in free space. Propagation through ABCD optical systems is also considered and a number of general properties of the kurtosis parameter are provided concerning the relationship between the extremals of the kurtosis and the position of the beam waist.

Surface water quality monitoring, classification, biological assessment and standards

Poor surface water quality is still a significant problem in many parts of the world. It can often limit the use of this vital resource and in more extreme cases can harm human and other life. A basic need is to establish the nature, extent and magnitude of the problems. To gain a quantitative picture it is necessary to undertake detailed quality and status assessments. Such assessments establish the scope of environmental impacts and effects, and provide a quantitative baseline against which future quality can be compared and progress monitored. Quality assessments or status reviews would enable the key problems and issues to be defined, and their magnitude and importance quantified. Problems for priority action can then be identified. Once key problems have been identified there are mechanisms to enact improvements and changes. These include the setting of standards and targets for water and sediment quality, quite often for defined actual or potential uses of the waters, such as for example for potable water supply and for fisheries. Compliance with the standards and progression towards the targets has to be assessed generally through appropriate monitoring. Monitoring might include biological as well as chemical and physical measurements of quality, and these might also be expressed as some form of index of quality. Periodic assessments of general quality on a national or international basis are also used to monitor overall progress. Nationally this might entail the use of general classification schemes expressing quality as a combined index or score, or individually for different components of the aquatic system, e.g. chemical, biological, aesthetic, and sediment quality.

Coupling Topology Dependence of Polarization-Transfer Efficiency in TOCSY and TACSY Experiments

The efficiency of selective and nonselective cross polarization in homo- and heteronuclear liquid-state nuclear magnetic resonance spectroscopy is investigated. A general classification scheme for TOCSY (total correlation spectroscopy) and TACSY (tailored correlation spectroscopy) experiments is introduced based on characteristic effective zero-quantum coupling tensors. The efficiency of polarization transfer with respect to transfer amplitude and transfer time is quantified and presented in the form of maps as a function of the relative coupling constants in systems consisting of three coupled spins. Characteristic differences in the polarization-transfer efficiency of TOCSY and TACSY variants are revealed and analyzed. Significant implications of these results are discussed for spin systems of practical interest.

Magneto-optics of Cu-related defects in polymorphic ZnS

High-resolution spectroscopy of weakly Cu-doped polymorphic ZnS crystals leads to the detection of new Cu 2+ Zn( 2E− 2T 2) zero-phonon lines in the 0.86 eV spectral region. As a result of Zeeman measurements a general classification scheme for the different lattice sites of the Cu 2+ Zn centres is presented. The axially distorted Cu 2+ Zn impurities show an anisotropical Zeeman pattern and a zero field splitting in the excited 2E-states. The order of magnitude of the g values indicates a strong Jahn-Teller interaction in the 2T 2-ground state.

Cathode Spot Phenomena in Low Current Vacuum Arcs on Arc‐Cleaned Electrode Surfaces I. Spot Size

AbstractCathode spots of vacuum arcs on pre‐arced surfaces have been studied using image converter photographs with suitable temporal and spatial resolution. Part I describes experimental details and presents observations of two coexisting spot modes: the smaller spots tend to move behind the larger spots. A possible relationship to the general classification scheme for arc cathode phenomena (Anders and Anders, 1989) is discussed.

Rotation of partially coherent beams propagating through free space

The orientation of a general partially coherent beam is described by introducing two pairs of orthogonal axes defined in terms of the second-order coherence features of the field. A general classification scheme for light beams is presented, based on their rotational behaviour under free propagation. This behaviour could be inferred from the values of certain measurable parameters at some plane. As an example of interest, the above classification is applied to Gaussian (coherent) beams with general astigmatism.

Beyond induction variables

Induction variable detection is usually closely tied to the strength reduction optimization. This paper studies induction variable analysis from a different perspective, that of finding induction variables for data dependence analysis. While classical induction variable analysis techniques have been used successfully up to now, we have found a simple algorithm based on the Static Single Assignment form of a program that finds all linear induction variables in a loop. Moreover, this algorithm is easily extended to find induction variables in multiple nested loops, to find nonlinear induction variables, and to classify other integer scalar assignments in loops, such as monotonic, periodic and wrap-around variables. Some of these other variables are now classified using ad hoc pattern recognition, while others are not analyzed by current compilers. Giving a unified approach improves the speed of compilers and allows a more general classification scheme. We also show how to use these variables in data dependence testing.

Taxonomy and conformational analysis of loops in proteins

We propose a general classification scheme for loops, aperiodic segments of protein structure. In an effort to avoid the geometric complexity created by non-repeating φ ψ angles, a morphologic definition that focuses upon the linearity and planarity of loops is utilized. Out of 432 loops (4 to 20 residues in length) extracted from 67 proteins, 205 are classified as linear (straps), 133 as non-linear and planar (omegas), and 86 as non-linear and non-planar (zetas). The remaining 8 are classified as compound loops because they contain a combination of strap, Ω, and ζ morphologies. We introduce a structural alphabet as a shorthand notation for describing local conformation. The symbols of this alphabet are based on the virtual dihedral angle joining four consecutive alpha carbons. The notation is used to provide a compact description of loop motifs in phosphate binding and calcium binding proteins. Since similar loop conformations form similar “words”, the structural sequence facilitates the search for common structural motifs in a family of loops. Contrary to the view of loops as “random coils”, we find loops to have positional preferences for amino acid residues analogous to those previously described for β-turns.

Grain boundaries in extended-chain polymers: Theory and experiment

Abstract A general geometrical classification scheme for grain boundaries in extended-chain polymers is presented. The analysis is an extension of a scheme originally presented by Bevis to describe deformation twins in polymers. Bevis recognized the importance of the orientation of the covalently bonded chain backbone within the crystallite, and referred to boundaries as ‘chain invariant’ or ‘chain rotation’ depending on whether chains in adjacent domains were parallel or not. We consider an important additional parameter: the orientation of the grain boundary plane. We classify those grain boundaries which are parallel to the two chain directions as ‘lateral’, and those which are not ‘axial’. These two parameters lead directly to four types of grain boundaries which are, in order of increasing energy: lateral chain invariant, lateral chain rotation, axial chain invariant, and axial chain rotation. Experimental evidence for these different types of boundaries are presented from High Resolution Electron Microscopy (HREM) studies of the rigid-rod polymer poly(paraphenylene benzobisoxazole) (PBZO or PBO). Possible molecular mechanisms for grain boundary motion are also discussed.

Binary Nonaqueous Solvent Systems Exhibiting Characteristics of Dielectric Continua

The continuum as a description of medium effects upon chemical processes often fails when applied to reactions in mixed solvents. Test specifications for the cosolvent as a continuum are now stated in a more precise form and these make use of the Kirkwood-Onsager and Block-Walker functions in constant. As a result, two additional binary solvents have been identified which appear to meet the tests, namely the 1-butanol : 1-propanol and nitrobenzene : acetonitrile cosolvent systems. In modeling the influence of polar solvents upon both electrolytic conductance and reaction kinetics in nonaqueous media most contemporary theories have initially made use of the dielectric continuum assumption to represent the solvent environment (Covington and Dickinson, 1973). When stated in its simplest form (Amis, 1966), that depicts the solvent as being the fully homogeneous surroundings for all solute species including reactants, products and transition state structures involved in the given process. Likewise, it requires that the polarity of that continuum be expressed as an appropriate function in either constant (E) alone or coupled with the square of the index of refraction for the bulk solvent. For the latter, the solvent reorganization energy functions of Marcus (1963) and their extension by Lay (1986) to hydrogen bonding solvents are representative of current continuum descriptions which have been applied to electron transfer processes in solution. By-and-large, the continuum serves best as a solvent environmental description for pure solvents of the aprotic dipolar (AD) and aprotic highly dipolar (AHD) classes in the Chastrette-Purcell (1985) general classification scheme. Beyond the discrete point (single solvent) tests of that assumption, the model has been used with reactions in binary solvent mixtures, and it is in such cosolvent systems which serve as dielectrically tunable media that the continuum is often quantitatively invalid. For mixed solvents, the failure of the model may arise from several sources at the molecular level. These include a range of solvent-solvent interactions from strong

Description, Taxonomy, and Explanation in Disaster Research

I am pleased that my paper stimulated the constructive commentaries of Professors Quarantelli, Drabek, and Turner. We seem to agree on several important points. First, the ideas proposed in my paper are grounded in sociological studies of disasters, are tentative, and should be abandoned wherever and whenever they don't help us to understand the phenomena we purport to study. Second, the development and refinement of concepts and theories in any science involves a healthy tension between inventing and discovering knowledge. Third, a life-cycle approach to emergencies and disasters is essential if we are to unravel how social structure and disaster interrelate. Fourth, there are practical dangers in making generalizations about social structure and disaster without also specifying the circumstances to which these generalizations apply. Fifth, because disaster research is necessarily a multidisciplinary field, we need to be flexible about defining boundaries of research. Sixth, in drawing on a wide variety of perspectives and theories, the resulting descriptions and explanations provided by each one will be partial and incomplete. Finally, the creation of special and more general classification schemes is an essential requirement of theory building, particularly when the subject matter is as inclusive as this one seems to be. But no classification scheme should become a sacred grail or straightjacket.

Grouping soils with similar properties for areal water budgeting and moisture mapping

Infiltration, field capacity and wilting point are the most important parameters used in water budgeting. Even for a small watershed of uniform weather characteristics, water budgeting must be performed for sub-areas of distinct soil properties. As the number of these sub-areas increases, the number of calculations involved in water budgeting also becomes large. For a large area including many different weather zones, the total number of water budget calculations, proportional to the product of weather zones and the number of sub-areas of uniform soil properties, can reach a magnitude which easily exceeds the capability of the most powerful computer available. Therefore, it is important to group soils with similar water movement and storage properties (the same can also be said about weather) to reduce water budgeting calculations. The magnitide of dispersion of soil properties in each sub-area needs to be estimated. The US Soil Taxonomy, a general soil classification scheme, was found to be useful to this grouping. The soil grouping technique based on the Soil Taxonomy was used in producing soil hydraulic properties maps for the Island of Oahu, Hawaii.

Front tracking and two-dimensional Riemann problems

A substantial improvement in resolution has been achieved for the computation of jump discontinuities in gas dynamics using the method of front tracking. The essential feature of this method is that a lower dimensional grid is fitted to and follows the discontinuous waves. At the intersection points of these discontinuities, two-dimensional Riemann problems occur. In this paper we study such two-dimensional Riemann problems from both numerical and theoretical points of view. Specifically included is a numerical solution for the Mach reflection, a general classification scheme for two-dimensional elementary waves, and a discussion of problems and conjectures in this area.

Classification of precipitation phenomena in ionic crystals

A general classification scheme is suggested for precipitation in supersaturated solid solutions of ionic crystals. The main types of precipitation are briefly characterized.

The inadequate treatment of psychology in general library classification schemes.

The inadequate treatment of psychology in general library classification schemes.

Genetic and nongenetic events in neoplasia

It has become increasingly evident that all chemical carcinogens do not act via the same mechanism of tumorigenicity. Based upon the extent of a chemical's interaction with DNA, a general classification scheme of various mutational and nonmutational theories of chemical carcinogenesis is presented. Compounds that directly interact with DNA are classified as genotoxic whereas those that do not interact directly with DNA are classified as epigenetic carcinogens. Under each general heading, several mutational and nonmutational mechanisms of carcinogenesis are believed to be possible. Data are also presented to support the existence of one such mechanism, an epigenetic-mutational theory of chemical carcinogenesis based upon recurrent cytotoxicity. In this case, increased regenerative DNA synthesis in response to tissue injury is believed to result in an enhancement of the normal spontaneous mutation rate, conceivably leading to a cellular transformation. The carcinogenic risk posed by such epigenetic carcinogens appears to differ greatly from that posed by genotoxic carcinogens. Thus, consideration of data concerning the possible mechanism of carcinogenicity of a chemical, along with pharmacokinetic data, will allow a better understanding of bioassay results and a more accurate assessment of carcinogenic risk.