Statistics of the geomagnetic secular variation for the past 5Ma

A new statistical model is proposed for the geomagnetic secular variation over the past 5Ma. Unlike previous models, the model makes use of statistical characteristics of the present day geomagnetic field. The spatial power spectrum of the non-dipole field is consistent with a white source near the core-mantle boundary with Gaussian distribution. After a suitable scaling, the spherical harmonic coefficients may be regarded as statistical samples from a single giant Gaussian process; this is the model of the non-dipole field. The model can be combined with an arbitrary statistical description of the dipole and probability density functions and cumulative distribution functions can be computed for declination and inclination that would be observed at any site on Earth's surface. Global paleomagnetic data spanning the past 5Ma are used to constrain the statistics of the dipole part of the field. A simple model is found to be consistent with the available data. An advantage of specifying the model in terms of the spherical harmonic coefficients is that it is a complete statistical description of the geomagnetic field, enabling us to test specific properties for a general description. Both intensity and directional data distributions may be tested to see if they satisfy the expected model distributions

Non-abelian instantons on a fuzzy four-sphere

We study the compatibility between the $BPST SU(2)$ instanton and the fuzzy four-sphere algebra. By using the projective module point of view as an intermediate step, we are able to identify a non-commutative solution of the matrix model equations of motion which minimally extends the SU(2) instanton solution on the classical sphere $S^4$. We also propose to extend the non-trivial second Chern class with the five-dimensional noncommutative Chern-Simons term

Reflexives in Veracruz Huastec

From the introduction: In this paper, I will consider various clause types in Huastec which are, in some sense, reflexive; this includes ordinary reflexives, which involve coreference, as well as other clauses. Two mutually exclusive morphosyntactic devices are used for reflexives in Huastec: reflexive pronouns, and verbal morphology: in this way, Huastec is like various European languages, including Spanish, Italian, Albanian, and Russian. Clauses involving reflexive pronouns are considered in Section 3, while those involving reflexive verbal morphology are considered in Section 4. The analysis presented here adopts the frameworks of Relational Grammar (RG) and Arc Pair Grammar (APG)

Basic Clause Structure in Veracruz Huastec

Huastec is a Mayan language spoken in east-central Mexico. It is considered important in Mayan studies since it alone represents a distinct branch within the Mayan family of languages; however, there is, in i^ct, relatively little published work on Huastec, especially on Huastec syntax. This thesis fills in some of this lacuna with a description of several aspects of Huastec clause structure. A general overview of Huastec grammar is presented in chapter 2, followed by several chapters each of which focuses on a separate topic of Huastec clause structure. The analyses in these chapters are presented within the theoretical frameworks of relational grammar and arc pair grammar. This theoretical perspec tive allows for a lucid account of the various structures considered. Huastec has clauses which involve several distinct types of structure found in other Mayan languages —passive, antipassive, indirect object advancement (dative shift), instrument advancement, possessor ascension (possessor dative), and others. Some of these have been identified in other descriptions of Huastec; however, this thesis provides a more detailed account of such structures in Huastec, some of which have remained unnoticed in other descriptions, and makes sharp distinctions between various ones which have previously been confused. While providing a descriptive account of interest to Mayanists, certain issues of theoretical interest are also raised. Many European languages have been found to include morphosyntactic devices reflecting syntactic structures that involve, as a minimal characteristic, the presence of a nominal which is both a subject and a direct object; one well-documented example is the use of essere as an auxiliary in Italian (cl Perlmutter 1978, Rosen 1981). (TI,e labels middle voice and medio-passive are often associated with such devices.) These devices and the exact constraints upon them vary greatly among these languages, yet the clauses in which they occur are generally limited to certain reflexive, passive, and unaccusative clauses. This thesis provides an account of similar clauses from a non-Indo-European language. In addi tion, the prediction is made that some language which has such a morphosyntactic device should also allow the same device in certain antipassive clauses; it is argued that this situation holds in Huastec. This, in turn, provides new and novel evidence, in favour the universal characterization of antipassives proposed by Postal (1977). A novel account of possessor ascension has been proposed by Rosen (1987); however, it is shown that this analysis is not viable for Huastec. Rather, it is argued that possessor ascension clauses in Huastec involve the raising of a possessor specifi cally to indirect object

Do you see what I see? Co-actor posture modulates visual processing in joint tasks

Interacting with other people is a ubiquitous part of daily life. A complex set of processes enable our successful interactions with others. The present research was conducted to investigate how the processing of visual stimuli may be affected by the presence and the hand posture of a co-actor. Experiments conducted with participants acting alone have revealed that the distance from the stimulus to the hand of a participant can alter visual processing. In the main experiment of the present paper, we asked whether this posture-related source of visual bias persists when participants share the task with another person. The effect of personal and co-actor hand-proximity on visual processing was assessed through object-specific benefits to visual recognition in a task performed by two co-actors. Pairs of participants completed a joint visual recognition task and, across different blocks of trials, the position of their own hands and of their partner's hands varied relative to the stimuli. In contrast to control studies conducted with participants acting alone, an object-specific recognition benefit was found across all hand location conditions. These data suggest that visual processing is, in some cases, sensitive to the posture of a co-actor

Complexation of lanthanides, actinides and transition metal cations with a 6-(1,2,4-triazin-3-yl)-2,2’:6’,2’’-terpyridine ligand: implications for actinide(III) /lanthanide(III) partitioning

The quadridentate N-heterocyclic ligand 6-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-2,2’:6’,2’’-terpyridine (CyMe4-hemi-BTBP) has been synthesized and its interactions with Am(III), U(VI), Ln(III) and some transition metal cations have been evaluated by X-ray crystallographic analysis, Am(III)/Eu(III) solvent extraction experiments, UV absorption spectrophotometry, NMR studies and ESI-MS. Structures of the 1:1 complexes with Eu(III), Ce(III) and the linear uranyl (UO22+) ion were obtained by X-ray crystallographic analysis, and showed similar coordination behavior to related BTBP complexes. In methanol, the stability constants of the Ln(III) complexes are slightly lower than those of the analogous quadridentate bis-triazine BTBP ligands, while the stability constant for the Yb(III) complex is higher. 1H NMR titrations and ESI-MS with lanthanide nitrates showed that the ligand forms only 1:1 complexes with Eu(III), Ce(III) and Yb(III), while both 1:1 and 1:2 complexes were formed with La(III) and Y(III) in acetonitrile. A mixture of isomeric chiral 2:2 helical complexes was formed with Cu(I), with a slight preference (1.4:1) for a single directional isomer. In contrast, a 1:1 complex was observed with the larger Ag(I) ion. The ligand was unable to extract Am(III) or Eu(III) from nitric acid solutions into 1-octanol, except in the presence of a synergist at low acidity. The results show that the presence of two outer 1,2,4-triazine rings is required for the efficient extraction and separation of An(III) from Ln(III) by quadridentate N-donor ligand

Quantizing String Theory in AdS_5 X S^5: Beyond the pp-Wave

In a certain kinematic limit, where the effects of spacetime curvature (and other background fields) greatly simplify, the light-cone gauge world-sheet action for a type IIB superstring on AdS_5 x S^5 reduces to that of a free field theory. It has been conjectured by Berenstein, Maldacena, and Nastase that the energy spectrum of this string theory matches the dimensions of operators in the appropriately defined large R-charge large-N_c sector of N=4 supersymmetric Yang--Mills theory in four dimensions. This holographic equivalence is thought to be exact, independent of any simplifying kinematic limits. As a step toward verifying this larger conjecture, we have computed the complete set of first curvature corrections to the spectrum of light-cone gauge string theory that arises in the expansion of AdS_5 x S^5 about the plane-wave limit. The resulting spectrum has the complete dependence on lambda = g_YM^2 N_c; corresponding results in the gauge theory are known only to second order in lambda. We find precise agreement to this order, including the N=4 extended supermultiplet structure. In the process, we demonstrate that the complicated schemes put forward in recent years for defining the Green--Schwarz superstring action in background Ramond-Ramond fields can be reduced to a practical (and correct) method for quantizing the string.Comment: 39 pages; substantial improvement

New non-abelian effects on D branes

We extend the Myers dielectric effect to configurations with angular momentum. The resulting time-dependent N D0 brane bound states can be interpreted as describing rotating fuzzy ellipsoids. A similar solution exists also in the presence of a RR magnetic field, that we study in detail. We show that, for any finite N, above a certain critical angular momentum is energetically more favorable for the bound state system to dissociate into an abelian configuration of N D0 branes moving independently. We have investigated this problem in the low-energy expansion of the non-abelian D brane action for generic N. In the case N=2 we find explicit solutions of the full non-abelian Born-Infeld D brane dynamics, which remarkably have the same structure and confirm the features of the low-energy approximation. We further study D string configurations representing fuzzy funnels deformed by the magnetic field and by the rotational motion.Comment: 14 pages, 5 figures. Improved version, reference adde

Predictions for PP-wave string amplitudes from perturbative SYM

The role of general two-impurity multi-trace operators in the BMN correspondence is explored. Surprisingly, the anomalous dimensions of all two-impurity multi-trace BMN operators to order g_2^2\lambda' are completely determined in terms of single-trace anomalous dimensions. This is due to suppression of connected field theory diagrams in the BMN limit and this fact has important implications for some string theory processes on the PP-wave background. We also make gauge theory predictions for the matrix elements of the light-cone string field theory Hamiltonian in the two string-two string and one string-three string sectors.Comment: 46 pages, 12 figures. V3:typos correcte