Cosmological constraints for the Cosmic Defect theory

The Cosmic Defect theory has been confronted with four observational constraints: primordial nuclear species abundances emerging from the big bang nucleosynthesis; large scale structure formation in the universe; cosmic microwave background acoustic scale; luminosity distances of type Ia supernovae. The test has been based on a statistical analysis of the a posteriori probabilities for three parameters of the theory. The result has been quite satisfactory and such that the performance of the theory is not distinguishable from the one of the Lambda-CDM theory. The use of the optimal values of the parameters for the calculation of the Hubble constant and the age of the universe confirms the compatibility of the Cosmic Defect approach with observations.Comment: 13 pages, 1 figure, in press on IJMP

Spherical symmetry in a dark energy permeated space-time

The properties of a spherically symmetric static space-time permeated of dark energy are worked out. Dark energy is viewed as the strain energy of an elastically deformable four dimensional manifold. The metric is worked out in the vacuum region around a central spherical mass/defect in the linear approximation. We discuss analogies and differences with the analogue in the de Sitter space time and how these competing scenarios could be differentiated on an observational ground. The comparison with the tests at the solar system scale puts upper limits to the parameters of the theory, consistent with the values obtained applying the classical cosmological tests.Comment: 14 pages, 1 figure, in press on Classical and Quantum Gravit

In vivo functional and myeloarchitectonic mapping of human primary auditory areas

In contrast to vision, where retinotopic mapping alone can define areal borders, primary auditory areas such as A1 are best delineated by combining in vivo tonotopic mapping with postmortem cyto- or myeloarchitectonics from the same individual. We combined high-resolution (800 μm) quantitative T(1) mapping with phase-encoded tonotopic methods to map primary auditory areas (A1 and R) within the "auditory core" of human volunteers. We first quantitatively characterize the highly myelinated auditory core in terms of shape, area, cortical depth profile, and position, with our data showing considerable correspondence to postmortem myeloarchitectonic studies, both in cross-participant averages and in individuals. The core region contains two "mirror-image" tonotopic maps oriented along the same axis as observed in macaque and owl monkey. We suggest that these two maps within the core are the human analogs of primate auditory areas A1 and R. The core occupies a much smaller portion of tonotopically organized cortex on the superior temporal plane and gyrus than is generally supposed. The multimodal approach to defining the auditory core will facilitate investigations of structure-function relationships, comparative neuroanatomical studies, and promises new biomarkers for diagnosis and clinical studies

Strong lensing in the Einstein-Straus solution

We analyse strong lensing in the Einstein-Straus solution with positive cosmological constant. For concreteness we compare the theory to the light deflection of the lensed quasar SDSS J1004+4112.Comment: 14 pages, 3 figures, 5 tables. To the memory of J\"urgen Ehlers v2 contains a note added during publication in GRG and less typo

Incomplete neutralization and other sub-phonemic durational differences in production and perception: Evidence from Dutch

Words which are expected to contain the same surface string of segments may, under identical prosodic circumstances, sometimes be realized with slight differences in duration. Some researchers have attributed such effects to differences in the words’ underlying forms (incomplete neutralization), while others have suggested orthographic influence and extremely careful speech as the cause. In this paper, we demonstrate such sub-phonemic durational differences in Dutch, a language which some past research has found not to have such effects. Past literature has also shown that listeners can often make use of incomplete neutralization to distinguish apparent homophones. We extend perceptual investigations of this topic, and show that listeners can perceive even durational differences which are not consistently observed in production. We further show that a difference which is primarily orthographic rather than underlying can also create such durational differences. We conclude that a wide variety of factors, in addition to underlying form, can induce speakers to produce slight durational differences which listeners can also use in perception

Orthographic vs. morphological incomplete neutralization effects

This study, following up on work on Dutch by Warner, Jongman, Sereno, and Kemps (2004. Journal of Phonetics, 32, 251–276), investigates the influence of orthographic distinctions and underlying morphological distinctions on the small sub-phonemic durational differences that have been called incomplete neutralization. One part of the previous work indicated that an orthographic geminate/singleton distinction could cause speakers to produce an incomplete neutralization effect. However, one interpretation of the materials in that experiment is that they contain an underlying difference in the phoneme string at the level of concatenation of morphemes, rather than just an orthographic difference. Thus, the previous effect might simply be another example of incomplete neutralization of a phonemic distinction. The current experiment, also on Dutch, uses word pairs which have the same underlying morphological contrast, but do not differ in orthography. These new materials show no incomplete neutralization, and thus support the hypothesis that orthography, but not underlying morphological differences, can cause incomplete neutralization effects

A Free-Form Lensing Grid Solution for A1689 with New Mutiple Images

Hubble Space Telescope imaging of the galaxy cluster Abell 1689 has revealed an exceptional number of strongly lensed multiply-imaged galaxies, including high-redshift candidates. Previous studies have used this data to obtain the most detailed dark matter reconstructions of any galaxy cluster to date, resolving substructures ~25 kpc across. We examine Abell 1689 (hereafter, A1689) non-parametrically, combining strongly lensed images and weak distortions from wider field Subaru imaging, and we incorporate member galaxies to improve the lens solution. Strongly lensed galaxies are often locally affected by member galaxies, however, these perturbations cannot be recovered in grid based reconstructions because the lensing information is too sparse to resolve member galaxies. By adding luminosity-scaled member galaxy deflections to our smooth grid we can derive meaningful solutions with sufficient accuracy to permit the identification of our own strongly lensed images, so our model becomes self consistent. We identify 11 new multiply lensed system candidates and clarify previously ambiguous cases, in the deepest optical and NIR data to date from Hubble and Subaru. Our improved spatial resolution brings up new features not seen when the weak and strong lensing effects are used separately, including clumps and filamentary dark matter around the main halo. Our treatment means we can obtain an objective mass ratio between the cluster and galaxy components, for examining the extent of tidal stripping of the luminous member galaxies. We find a typical mass-to-light ratios of M/L_B = 21 inside the r<1 arcminute region that drops to M/L_B = 17 inside the r<40 arcsecond region. Our model independence means we can objectively evaluate the competitiveness of stacking cluster lenses for defining the geometric lensing-distance-redshift relation in a model independent way.Comment: 23 pages with 25 figures Replced with MNRAS submitted version. Some figures have been corrected and minor text edit

On Gravitational Waves in Spacetimes with a Nonvanishing Cosmological Constant

We study the effect of a cosmological constant $\Lambda$ on the propagation and detection of gravitational waves. To this purpose we investigate the linearised Einstein's equations with terms up to linear order in $\Lambda$ in a de Sitter and an anti-de Sitter background spacetime. In this framework the cosmological term does not induce changes in the polarization states of the waves, whereas the amplitude gets modified with terms depending on $\Lambda$. Moreover, if a source emits a periodic waveform, its periodicity as measured by a distant observer gets modified. These effects are, however, extremely tiny and thus well below the detectability by some twenty orders of magnitude within present gravitational wave detectors such as LIGO or future planned ones such as LISA.Comment: 8 pages, 4 figures, accepted for publication in Physical Review