Selfdual 2-form formulation of gravity and classification of energy-momentum tensors

It is shown how the different irreducibility classes of the energy-momentum tensor allow for a Lagrangian formulation of the gravity-matter system using a selfdual 2-form as a basic variable. It is pointed out what kind of difficulties arise when attempting to construct a pure spin-connection formulation of the gravity-matter system. Ambiguities in the formulation especially concerning the need for constraints are clarified.Comment: title changed, extended versio

Novel Candidate Genes Identified in the Brain during Nociception in Common Carp (Cyprinus carpio) and Rainbow Trout (Oncorhynchus mykiss)

Recent studies have demonstrated that teleost fish possess nociceptors that detect potentially painful stimuli and that the physiological properties of these fibres are markedly similar to those found in mammals. This finding led to suggestions of possible pain perception in fish, contrary to the view that the sensory response in these animals is limited to the spinal cord and hindbrain and as such is reflexive. Therefore, the aim of this study was to determine if the brain is active at the molecular level by using a microarray analysis of gene expression in the forebrain, midbrain and hindbrain of two fish species. A comparison between the two species at different time points showed that many genes were differentially regulated in response to a noxious stimulus compared with controls. A number of genes that are involved in mammalian nociception, such as brain-derived neurotrophic factor (BDNF) and the cannabinoid CB1 receptor were regulated in the fish brain after a nociceptive event. Novel candidates that showed significant regulation in both species were also identified. In particular, the Van Gogh-like 2 gene, was regulated in both carp and trout and should be pursued to establish its precise role in nociception

Behavioural Analysis of a Nociceptive Event in Fish: Comparisons Between Three Species Demonstrate Specific Responses

Nociception is the sensory mechanism by which potentially harmful stimuli are detected in animals and humans. The behavioural responses to noxious stimulation have been studied in two fish species thus far. However, since species-specific differences are seen in mammals, more species need to be examined to determine whether nociceptive responses are generic in fish. The present study investigated the behavioural and respiratory response to an acute noxious or potentially painful stimulus in common carp (Cyprinus carpio), zebrafish (Danio rerio) and rainbow trout (Oncorhynchus mykiss). Behavioural parameters such as frequency of swimming, use of cover and any anomalous behaviour were measured along with ventilation rate before and after noxious stimulation in the carp and zebrafish. Although no differences in behavioural or ventilation rate response were observed between noxiously stimulated carp and control fish, anomalous behaviours of rocking from side to side and rubbing of lips against the tank walls were observed in two of the five fish. In contrast, zebrafish displayed a significant reduction in frequency of swimming and an increase in ventilation rate, which was similar to the results obtained from rainbow trout. Zebrafish did not display any anomalous behaviour. These dissimilarities in response to potentially painful stimulation demonstrate that there are species-specific behavioural and physiological responses to a nociceptive event in fish

Cognitive demands of face monitoring: Evidence for visuospatial overload

Young children perform difficult communication tasks better face to face than when they cannot see one another (e.g., Doherty-Sneddon & Kent, 1996). However, in recent studies, it was found that children aged 6 and 10 years, describing abstract shapes, showed evidence of face-to-face interference rather than facilitation. For some communication tasks, access to visual signals (such as facial expression and eye gaze) may hinder rather than help children’s communication. In new research we have pursued this interference effect. Five studies are described with adults and 10- and 6-year-old participants. It was found that looking at a face interfered with children’s abilities to listen to descriptions of abstract shapes. Children also performed visuospatial memory tasks worse when they looked at someone’s face prior to responding than when they looked at a visuospatial pattern or at the floor. It was concluded that performance on certain tasks was hindered by monitoring another person’s face. It is suggested that processing of visual communication signals shares certain processing resources with the processing of other visuospatial information

The Absence of Positive Energy Bound States for a Class of Nonlocal Potentials

We generalize in this paper a theorem of Titchmarsh for the positivity of Fourier sine integrals. We apply then the theorem to derive simple conditions for the absence of positive energy bound states (bound states embedded in the continuum) for the radial Schr\"odinger equation with nonlocal potentials which are superposition of a local potential and separable potentials.Comment: 23 page

The rotation curve and mass-distribution in highly flattened galaxies

A new method is developed which permits the reconstruction of the surface-density distribution in the galactic disk of finite radius from an arbitrary smooth distribution of the angular velocity via two simple quadratures. The existence of upper limits for disk's mass and radius during the analytic continuation of rotation curves into the hidden (non-radiating) part of the disk is demonstrated.Comment: 13 pages, 2 figure

Investigation of Van Gogh-like 2 mRNA Regulation and Localisation in Response to Nociception in the Brain of Adult Common Carp (Cyprinus carpio)

The Van Gogh-like 2 (vangl2) gene is typically associated with planar cell polarity pathways, which is essential for correct orientation of epithelial cells during development. The encoded protein of this gene is a transmembrane protein and is highly conserved through evolution. Van Gogh-like 2 was selected for further study on the basis of consistent regulation after a nociceptive stimulus in adult common carp and rainbow trout in a microarray study. An in situ hybridisation was conducted in the brain of mature common carp (Cyprinus carpio), 1.5 and 3 h after a nociceptive stimulus comprising of an acetic acid injection to the lips of the fish and compared with a saline-injected control. The vangl2 gene was expressed in all brain regions, and particularly intensely in neurons of the telencephalon and in ependymal cells. In the cerebellum, a greater number (P = 0.018) of Purkinje cells expressed vangl2 after nociception (n=7) compared with controls (n = 5). This regulation opens the possibility that vangl2 is involved in nociceptive processing in the adult fish brain and may be a novel target for central nociception in vertebrates

General Framework for phase synchronization through localized sets

We present an approach which enables to identify phase synchronization in coupled chaotic oscillators without having to explicitly measure the phase. We show that if one defines a typical event in one oscillator and then observes another one whenever this event occurs, these observations give rise to a localized set. Our result provides a general and easy way to identify PS, which can also be used to oscillators that possess multiple time scales. We illustrate our approach in networks of chemically coupled neurons. We show that clusters of phase synchronous neurons may emerge before the onset of phase synchronization in the whole network, producing a suitable environment for information exchanging. Furthermore, we show the relation between the localized sets and the amount of information that coupled chaotic oscillator can exchange