Showing papers on "Valency published in 2001"

Verb Sense and Verb Subcategorization Probabilities

Abstract: The probabili stic relation between verbs and their arguments plays an important role in psychological theories of human language processing. For example, Ford, Bresnan and Kaplan (1982) proposed that verbs li ke position have two lexical forms: a more preferred form that subcategorizes for three arguments (SUBJ, OBJ, PCOMP) and a less preferred form that subcategorizes for two arguments (SUBJ, OBJ). Many recent psychological experiments suggest that humans use these kinds of verb-argument preferences as an essential part of the process of sentence interpretation. (Cli fton et al. 1984, Ferreira & McClure 1997, Garnsey et al. 1997, MacDonald 1994, Mitchell & Holmes 1985, Boland et al. 1990, Trueswell et al. 1993). It is not completely understood how these preferences are realized, but one possible model proposes that each lexical entry for a verb expresses a conditional probability for each potential subcategorization frame (Jurafsky 1996, Narayanan and Jurafsky 1998).

Local structure and chemical valency of Mn impurities in wide-band-gap III-V magnetic alloy semiconductors Ga1-xMnxN

Abstract: Local structure and effective chemical valency of Mn impurity atoms incorporated in wide-band-gap (Ga,Mn)N epilayers have been investigated by using x-ray absorption fine structure techniques. The x-ray results provide direct evidence for the substitution of majority Mn atoms for the Ga sites in GaN, with an effective valency close to Mn(II), up to a rather high Mn concentration about 2 at. %. A small fraction of the impurity atoms could also form Mn clusters.

Cu valency change induced by O doping in YBCO

Abstract: An ab initio local spin density study of YBa2Cu3O6, YBa2Cu3O6.5, and YBa2Cu3O7 is presented. The method includes self-interaction corrections for the Cu d states, which enables a description of various valency configurations of both planar and chain Cu atoms. For YBa2Cu3O6 the antiferromagnetic and insulating state is described with planar (chain) Cu occurring in a divalent (trivalent) state. The evolution in the CuO2 plane from insulating to metallic behavior upon oxygenation is accomplished by the delocalization of the majority Cu d(x2-y2)-O2 p(x)-O3 p(y) band.

Arc-Transitive Cayley Graphs of Valency at Most Four on Abelian Groups

Abstract: In this paper we give a complete classification for arc-transitive and one-regular Cayley graphs of valency at most four on finite abelian groups.

The use of a segmented tool for the analysis of electrochemical machining

Abstract: A planar workpiece/planar segmented tool experimental configuration has been used to collect current–time data for the electrochemical machining (ECM) of Inconel 718 (In718) and stainless steel (SS316). As with previous measurements, theoretical analysis of the chronoamperometric data has been used to obtain values for the characteristic parameters of ECM under characteristic machining conditions, but the segmented tool allows this for each segment. These parameters are the valency, n, and k, from which the minimum voltage required to initiate machining, V 0, and the electrolyte conductivity, κ can be obtained. The variation of n, V 0 and κ between segments enables ECM conditions along the flow path length to be probed. Measurements on In718 in nitrate electrolyte have shown a small increase in electrolyte conductivity along the flow path. Tool segments which overlap the workpiece ends have been employed to measure edge effects in the ECM process; no significant edge effects were found when machining In718 in nitrate. The temporal and spatial dependences of a change in valency previously observed during the machining of SS316 have also been studied for the first time. Regions of low valency (n = 2.1) dissolution (downstream) and high valency (upstream, n = 3.0) dissolution were observed, with an intermediate region with monotonically decreasing valency where 3.0 > n > 2.1.

From dictionary to corpus to self-organizing dictionary: learning valency associations in the face of variation and change

Abstract: ing over specific lexically-governed particles and prepositions and specific predicate selectional preferences, but including some `derived' / `alternant' semi-productive, and therefore only semipredictable, bounded dependency constructions, such as particle or dative movement, there are at least 163 valency frames associated with verbal predicates in (current) English (Briscoe, 2000). In this paper, I will review the work that my colleagues and I have done to learn (semi-)automatically this very large number of associations between individual verbal predicates and valency frames. Access to a comprehensive and accurate valency lexicon is critical for the development of robust and accurate parsing technology capable of recovering predicate-argument relations (and thus logical forms) from free text or transcribed speech. Without this information it is possible to `chunk’ input into phrases but not to distinguish arguments from adjuncts or resolve most phrasal attachment ambiguities. Furthermore, for statistical parsers it is not enough to know the associations of predicates to valency frames, it is also critical to know the relative frequency of such associations given a specific predicate. Such information is a core component of that required to `lexicalize’ a probabilistic parser, and it is now well–established that lexicalization is essential for accurate disambiguation (e.g. Collins, 1997, Carroll et al, 1998). While state-of-the-art wide-coverage grammars of English, capable of recovering predicateargument structure and expressed as a unification-based phrase structure grammar, have on the order of 1000 rules, it is clear that the number of associations between valency frames and predicates needed in a lexicon for such a grammar will be much higher.

Variable Fe-valence as an effect of angular correlations?

Abstract: Long-range order starts to form as a spherical periodic electron-staic-structure resonance. The selforganized adjustments of the static structure to the electronic constraints, and vice versa, the electronic system via variations of the mass-density or the effective valency to the static structure, all optimize the resonance. The latter effect plays an important role in amorphous and quasicrystalline alloys containing late transition elements and aluminium.

How syntax restricts the lexicon: particle verbs and internal arguments

Abstract: Particles in German have the capacity to introduce new arguments when they combine with a verb. Based on this observation, I argue that the internal arguments of a particle verb are always introduced by the particle. I suggest that this follows from the fact that syntactically, the particle is the head of a maximal projection that occupies the single complement position of the verb; therefore, none of the base verb's arguments can be linked to a syntactic object position if a particle is present. In providing empirical evidence for my claim, I discuss in some detail the derivation of a variety of particle verbs, representing their semantics as Lexical Conceptual Structures, according to the framework developed in Jackendoff (1983, 1990)

Studies on compensating valency substituted BaTi(1−x)Mn x/2Nb x/2O3 ceramics

Abstract: The paper reports investigations of relative permittivity, er, electrical conductivity, σ, saturation polarization, Ps, infrared absorption and structural properties of compensating valency substituted BaTiO3. The compositions investigated are BaTi(1−x)Mnx/2Nbx/2O3 forx = 0.00; 0.025; 0.05; 0.1; 0.2; 0.4. The compositions forx < 0.1 are observed to be ferroelectric and the transition temperature and value of er are observed to decrease as concentration of substitution is increased. The dielectric investigations are carried out on two sets of samples (i) as sintered and (ii) annealed. Annealing is observed to improve quality factor‘Q’ of the materials with a consequent reduction in the er. The observations on er and saturation polarization suggest that additional material engineering efforts are required to improve the material properties.

Effect of nonzero chain diameter on "DNA" condensation.

Abstract: We present a simple model to investigate the effect of chain diameter on multivalent-counterion-induced attractions between two charged chains. In our minimal model, the chains are rigid rods of diameter D with a uniform charge density on the surface, and the counterions are point ions. As a function of the separation between two rods, we find a repulsive barrier in the free energy whose height increases with D. We have also explored the effect of counterion valency Z on the interaction. For parameters characteristic of DNA, we find that a minimum valency of Z=3 is required to produce condensation. We also find that the shape of the potential is fairly insensitive to Z for Z>/=3. These results are consistent with experimental observations of DNA condensation.

The Valency Effect on Reaction Pathways in Heterogeneous Catalysis: Insight from Density Functional Theory Calculations

Abstract: Density functional theory (DFT) has been used to determine reaction pathways for several reactions taking place on Pt and Cu surfaces. On Pt(111) all the elementary steps in the hydrogenation of carbon to methane, nitrogen to ammonia, and oxygen to water were investigated. Also on Pt(111) the reactions of C with O and N were studied, and on Cu(111) the reaction of C with H was examined. It is found that reaction pathways are related to the valency of the reactants involved. As the valency of a reactant decreases so too does the coordination number of the site at which the transition state is located. In the hydrogenation reactions on Pt(111) it was found that monovalent adsorbates (for example, CH3, NH2 and OH) tend to make transition states close to top sites; divalent adsorbates (CH2, NH and O) near bridge sites; and tri- and tetra-valent adsorbates (CH, N and C) near three-fold hollow sites. This relationship between the transition state and the valency applies equally to the C+O and C+N reactions on Pt(111), the C+H reaction on Cu(111), and many others from the literature. On this basis, we have developed rules to facilitate the prediction of catalytic reaction pathways without recourse to experimental or theoretical investigations.

Enhancing the Valency Dictionary of Czech Verbs: Tectogrammatical Annotation

Abstract: A syntactic lexicon of verbs with the subcategorization information is crucial for NLP. Two phases of creating such lexicon are presented. The first phase consists of the automatic preprocessing of source data-particular valency frames are proposed. Where it is possible, the functors are assigned, otherwise the set of possible functors is proposed. In the second phase the proposed valency frames are manually refined.

Subjects and valency-changing mechanisms in Latvian

Abstract: This paper discusses the syntactic basis for the existence of the grammatical relation of subject in Latvian. A point of departure for the discussion is the position that grammatical relations need not be clearcut categories, but may be better defined in terms of prototypicality. By applying various criteria for subjecthood in Latvian, one arrives at a multi-factor definition of subject in the language. During the discussion it becomes clear that Latvian has several syntactic entities which only to some extent may be called subjects, as they share only a subset of the properties found in prototypical subjects. A discussion of valencychanging mechanisms in Latvian is included towards the end of the paper, as these mechanisms shed yet more light on the question of subjecthood in the language. Apart from passive constructions, also reflexives with the meaning of a middle voice and the category of debitive are treated in this part of the paper.

Modified lewis theory part 2. coordinate and nonintegral bonds

Abstract: The modification to Lewis’s theory of valency proposed in Part 1 is extended to molecules containing coordinate bonds. A further modification to the theory is proposed to make it applicable to molecules containing nonintegral bonds (e.g., B2H6). [Chem. Educ. Res. Pract. Eur.: 2001, 2, 179-182]

Diffraction by Carbon-Based Tubular and Helical Structures

Abstract: In the Periodic Table of the Elements carbon is listed as crystallizing in the hexagonal structure. Illustrated in Fig.1a, the structure, consists of planar layers of carbon atoms arranged in honeycomb lattices called graphene sheets. Within a sheet, the atoms are covalently bonded, with a valency of 3, to three equidistant neighbors 0.14 nm away. The sheets are loosely piled up on top of each other every 0.34 nm in an alternating ABAB... sequence producing a threedimensional structure of hexagonal unit cell. There are various other stacking arrangements possible but this need not concern us here. This allotrope, known as graphite, is the most stable and most abundant solid form of pure carbon found in nature. A slightly less stable but vastly less abundant crystallographic form is diamond which has the cubic structure shown in Fig.1b. Here each atom, exhibiting valency 4, is covalently coordinated to four neighbors at the apexes of a regular tetrahedron.

Density of states in the gap, connected with dipole defects in the chalcogenide vitreous semiconductors

Abstract: Any deviations of the structure of glassy semiconductors from the structure of the appropriate crystals result in the occurrence of states in the gap. In chalcogenide glassy semiconductors the distribution of states in the gap exhibits features specific to discrete [1-3] spectra, and quasi-continuous one [4-6]. As follows from the analysis of the dependence of mobility and conductivity on the electrical field in As2Se3 the existence of smooth distribution upon energy of the states near to edges of a valence band is possible. From the analysis of the hole mobility it results the existence of energy levels situated at 0.45 eV from the edge of the valency band. The nature of these states is not quite clear. It is supposed that local defects, which are related to the changes of chemical bond and coordination, form, as a rule, states, deeply laying in a gap, with enough precisely fixed energy forming a discrete spectrum. In turn, fluctuation in bond lengts, valency and torsion angles results in the formation of gap states, whose density N (E) falls down deep into gap and is characterized by a quasicontinuous spectrum. However, the local defect, too, in case its geometry is accompanied by significant fluctuations of potential, can form group of the states, distributed enough deep in a gap, and near to the edges of a valence band and conductivity, thus forming a spectrum.

Valency and Argument Structure in Syntax

Abstract: The purpose of this article is to explain the valency and argument structure of the predicate. The article begins with definitions of valency and argument structure. This then leads to illustration of a number of ways in which arguments are removed from, or added to, the argument structure, whereby changes in the valency of the basic predicate may be brought about. The article demonstrates that the argument structure can also be altered or rearranged without involving a change of valency. Also illustrated is how languages may keep the valency of the derived predicate from exceeding that of the basic predicate. The article addresses the question of whether or not identical coding of nominals – especially in the context of valency increasing – entails doubling of grammatical relations. Finally, a brief discussion of how valency-changing operations are handled or represented in current grammatical theories is provided.