Anisotropic fluid inside a relativistic star

An anisotropic fluid with variable energy density and negative pressure is proposed, both outside and inside stars. The gravitational field is constant everywhere in free space (if we neglect the local contributions) and its value is of the order of $g = 10^{-8} cm/s^{2}$, in accordance with MOND model. With $\rho,~ p \propto 1/r$, the acceleration is also constant inside stars but the value is different from one star to another and depends on their mass $M$ and radius $R$. In spite of the fact that the spacetime is of Rindler type and curved even far from a local mass, the active gravitational energy on the horizon is $-1/4g$, as for the flat Rindler space, excepting the negative sign.Comment: 9 pages, refs added, new chapter added, no figure

Quantum backreaction in evolving FLRW spacetimes

Quantum fluctuations of a nonminimally coupled scalar field in D-dimensional homogeneous and isotropic background are calculated within the operator formalism in curved models with time evolutions of the scale factor that allow smooth transitions between contracting and expanding and between decelerating and accelerating regimes. The coincident propagator is derived and used to compute the one-loop backreaction from the scalar field. The inflationary infrared divergences are absent in Bunch-Davies vacuum when taking into account a preceding cosmological era or spatial curvature which can be either positive or negative. It is found that asymptotically, the backreaction energy density in the minimally coupled case grows logarithmically with the scale factor in quasi-de Sitter space, and in a class of models decays in slow-roll inflation and grows as a power-law during super-inflation. The backreaction increases generically in a contracting phase or in the presence of a negative nonminimal coupling. The effects of the coupling and renormalization scale upon the quantum fluctuations together with the novel features due to nontrivial time evolution and spatial curvature are clarified with exact solutions and numerical examples.Comment: 23 pages, 6 figure

Perturbations in electromagnetic dark energy

It has been recently proposed that the presence of a temporal electromagnetic field on cosmological scales could explain the phase of accelerated expansion that the universe is currently undergoing. The field contributes as a cosmological constant and therefore, the homogeneous cosmology produced by such a model is exactly the same as that of $\Lambda$CDM. However, unlike a cosmological constant term, electromagnetic fields can acquire perturbations which in principle could affect CMB anisotropies and structure formation. In this work, we study the evolution of inhomogeneous scalar perturbations in this model. We show that provided the initial electromagnetic fluctuations generated during inflation are small, the model is perfectly compatible with both CMB and large scale structure observations at the same level of accuracy as $\Lambda$CDM.Comment: 12 pages, 3 figures. Added new comments to match the published versio

Cosmic Parallax in Ellipsoidal Universe

The detection of a time variation of the angle between two distant sources would reveal an anisotropic expansion of the Universe. We study this effect of "cosmic parallax" within the "ellipsoidal universe" model, namely a particular homogeneous anisotropic cosmological model of Bianchi type I, whose attractive feature is the potentiality to account for the observed lack of power of the large-scale cosmic microwave background anisotropy. The preferred direction in the sky, singled out by the axis of symmetry inherent to planar symmetry of ellipsoidal universe, could in principle be constrained by future cosmic parallax data. However, that will be a real possibility if and when the experimental accuracy will be enhanced at least by two orders of magnitude.Comment: 9 pages, 2 figures, 1 table. Revised version to match published version. References adde

Anisotropic dark energy and ellipsoidal universe

A cosmological model with anisotropic dark energy is analyzed. The amount of deviation from isotropy of the equation of state of dark energy, the skewness \delta, generates an anisotropization of the large-scale geometry of the Universe, quantifiable by means of the actual shear \Sigma_0. Requiring that the level of cosmic anisotropization at the time of decoupling is such to solve the "quadrupole problem" of cosmic microwave background radiation, we find that |\delta| \sim 10^{-4} and |\Sigma_0| \sim 10^{-5}, compatible with existing limits derived from the magnitude-redshift data on type Ia supernovae.Comment: 10 pages, 3 figures. Revised version to match published version. References adde

Inducing empathy towards upper limb impairments using a physical device and virtual reality

Abstract. Empathy is the ability to understand concepts deeply and intimately from the perspective of another person. Having this empathetic understanding of different medical conditions will help make more informed decisions when designing for a particular condition and increase the motivation for providing higher quality results. However, it can be quite challenging for people to easily gain this kind of empathetic knowledge without fully comprehending the extent to which a particular impairment affects someone’s day-to-day life. One of the most popular and effective methods of inducing empathy towards impairments is the use of empathy simulations. The basic concept of empathy simulations is to realistically simulate the limitations posed by an impairment so that the participant can gain a first-hand experience of what it is like to live with the impairment. Traditionally, these simulations were created using various physical means, but lately the use of virtual reality devices in these simulations has become more common. Virtual reality is essentially technology that allows the user to embody another persons perspective, which makes it exceptionally suitable for empathy simulations. The aim of our study was to investigate the generation of empathy towards upper extremity motor impairments using a mixture of physical and virtual means. For the purposes of this study, we built an arm mobility restricting harness to mimic an upper extremity motor impairment and a virtual reality environment of a home kitchen where the simulations took place. Two groups of volunteer participants experienced the simulation by performing simple tasks in the virtual reality environment while being limited by the mobility restricting harness. The difference between the groups was in having to recite different backstories for their simulated characters. Backstory for group 1 was in first-person, and group 2 for group in third-person. The stories were thought to target affective and cognitive empathy differently. The participants’ level of empathy was measured once before the simulation and once after the simulation using a collection of standardized questionnaires. The study showed significant increase in the level of emotional contagion over all participants (p < 0.044*) suggesting that the simulation increased the participants’ level of empathy in that category. No significant difference was measured between backstories, however, the results suggest the first-person story to assist cognitive empathy. The study also showed that the group with the backstory in first-person had better scores in all categories of embodiment suggesting that the first-person backstory enabled participants to better relate to their virtual character. Despite some promising results, further studies are needed to investigate empathy generation using a mixed physical and virtual empathy simulations

Depressive symptoms are associated with analgesic use in people with Alzheimer's disease: Kuopio ALSOVA study.

Neuropsychiatric symptoms of Alzheimer's disease (AD) such as depression may be associated with pain, which according to the literature may be inadequately recognized and managed in this population. This study aimed to identify the factors associated with analgesic use in persons with AD; in particular, how AD severity, functional status, neuropsychiatric symptoms of AD, co-morbidities and somatic symptoms are associated with analgesic use. 236 community-dwelling persons with very mild or mild AD at baseline, and their caregivers, were interviewed over five years as part of the prospective ALSOVA study. Generalized Estimating Equations (GEEs) were used to estimate unadjusted and adjusted odds ratios (ORs) for the factors associated with analgesic use over a five year follow-up. The proportion of persons with AD using any analgesic was low (13.6%) at baseline and remained relatively constant during the follow-up (15.3% at Year 5). Over time, the most prevalent analgesic changed from non-steroidal anti-inflammatories (8.1% of persons with AD at Year 1) to acetaminophen (11.1% at Year 5). Depressive symptoms (measured by the Beck Depression Inventory, BDI) were independently associated with analgesic use, after effects of age, gender, education, AD severity, comorbidities and somatic symptoms were taken into account. For every one unit increase in BDI, the odds of analgesic use increased by 4% (OR = 1.04, 95% confidence interval CI = 1.02-1.07). Caregiver depressive symptoms were not statistically significantly associated with analgesic use of the person with AD. Depressive symptoms were significantly associated with analgesic use during the five year follow-up period. Possible explanations warranting investigation are that persons with AD may express depressive symptoms as painful somatic complaints, or untreated pain may cause depressive symptoms. Greater awareness of the association between depressive symptoms and analgesic use may lead to safer and more effective prescribing for these conditions

Project Andvari: A Digital Portal to the Visual World of Early Medieval Northern Europe

Project Andvari is designed to provide integrated access to dispersed collections of northern European art and artifacts of the early medieval period (4th-12th centuries). Our goal is to create a digital portal offering aggregated search options and enhanced metadata. Funding is requested to convene an international workshop for humanities scholars, museum professionals, and technology experts to refine the conceptual design of the proposed research tool and identify its technological requirements in preparation for a pilot project. Ultimately, Project Andvari will facilitate interdisciplinary research in art, archaeology, history, and literary and religious studies of the northern periphery of medieval Europe. It will allow users to study visual culture across media and beyond traditional geographical and disciplinary boundaries. Its innovative application of search methods will promote analyses of relationships of artifacts and cultures, and help us discover the hitherto unnoticed

Cosmology of a Scalar Field Coupled to Matter and an Isotropy-Violating Maxwell Field

Motivated by the couplings of the dilaton in four-dimensional effective actions, we investigate the cosmological consequences of a scalar field coupled both to matter and a Maxwell-type vector field. The vector field has a background isotropy-violating component. New anisotropic scaling solutions which can be responsible for the matter and dark energy dominated epochs are identified and explored. For a large parameter region the universe expands almost isotropically. Using that the CMB quadrupole is extremely sensitive to shear, we constrain the ratio of the matter coupling to the vector coupling to be less than 10^(-5). Moreover, we identify a large parameter region, corresponding to a strong vector coupling regime, yielding exciting and viable cosmologies close to the LCDM limit.Comment: Refs. added, some clarifications. Published in JHEP10(2012)06