"Dark energy" in the Local Void

The unexpected discovery of the accelerated cosmic expansion in 1998 has filled the Universe with the embarrassing presence of an unidentified "dark energy", or cosmological constant, devoid of any physical meaning. While this standard cosmology seems to work well at the global level, improved knowledge of the kinematics and other properties of our extragalactic neighborhood indicates the need for a better theory. We investigate whether the recently suggested repulsive-gravity scenario can account for some of the features that are unexplained by the standard model. Through simple dynamical considerations, we find that the Local Void could host an amount of antimatter ($\sim5\times10^{15}\,M_\odot$) roughly equivalent to the mass of a typical supercluster, thus restoring the matter-antimatter symmetry. The antigravity field produced by this "dark repulsor" can explain the anomalous motion of the Local Sheet away from the Local Void, as well as several other properties of nearby galaxies that seem to require void evacuation and structure formation much faster than expected from the standard model. At the global cosmological level, gravitational repulsion from antimatter hidden in voids can provide more than enough potential energy to drive both the cosmic expansion and its acceleration, with no need for an initial "explosion" and dark energy. Moreover, the discrete distribution of these dark repulsors, in contrast to the uniformly permeating dark energy, can also explain dark flows and other recently observed excessive inhomogeneities and anisotropies of the Universe.Comment: 6 pages, accepted as a Letter to the Editor by Astrophysics and Space Scienc

Do we live in the universe successively dominated by matter and antimatter?

We wonder if a cyclic universe may be dominated alternatively by matter and antimatter. Such a scenario demands a mechanism for transformation of matter to antimatter (or antimatter to matter) during the final stage of a big crunch. By giving an example, we have shown that in principle such a mechanism is possible. Our mechanism is based on a hypothetical repulsion between matter and antimatter, existing at least deep inside the horizon of a black hole. When universe is reduced to a supermassive black hole of a small size, a very strong field of the conjectured force might create (through a Schwinger type mechanism) particle-antiparticle pairs from the quantum vacuum. The amount of antimatter created from the vacuum is equal to the decrease of mass of the black hole and violently repelled from it. When the size of the black hole is sufficiently small, the creation of antimatter may become so fast, that matter of our Universe might be transformed to antimatter in a fraction of second. Such a fast conversion of matter into antimatter may look as a Big Bang. Our mechanism prevents a singularity; a new cycle might start with an initial size more than 30 orders of magnitude greater than the Planck length, suggesting that there is no need for inflationary scenario in Cosmology. In addition, there is no need to invoke CP violation for explanation of matter-antimatter asymmetry. Simply, our present day Universe is dominated by matter, because the previous universe was dominated by antimatter

Seasonal evolution of hydrographic properties in the Ross Sea, Antarctica, 1996–1997

This paper briefly describes hydrographic and chemical results from four seasonal process cruises in the Joint Global Ocean Flux Study (JGOFS) Antarctic Environment and Southern Ocean Process Study (AESOPS) in the Ross Sea. The data include temperature, salinity, oxygen, nutrients (NO 3 −, NO 2 −, NH 4 +, PO 4 −3, Si(OH) 4), titration alkalinity (TA), and total inorganic CO 2 (TCO 2). In early spring (mid-October to early November 1996) ice cover was near 100%. The water column exhibited only small ranges of potential temperature, salinity, nutrients, TA and TCO 2. These nearly uniform conditions observed during this cruise were used as initial conditions from which to evaluate seasonal changes in biogeochemical properties. Later in the spring (November/December) of the following year (1997), an expanded polynya was present. In the summer (January) 1997, the sea-ice cover was minimal. Meltwater dilution and warming of exposed surface waters were at their maximum. Finally, in early austral autumn (April 1997) rapid cooling and freezing of surface waters and intensified vertical mixing of the water column resulted in a return toward winter conditions, but with significant depletion of nutrients still evident in surface waters. Modified circumpolar deep water (MCDW) was observed at ∼175°E., varying in location zonally with time. Beneath the MCDW, near the eastern end of the section at ∼180°, northward intrusion of ice shelf water (ISW) was persistent though variable. Among the biogeochemical changes observed along this section were: (1) Significant ammonium accretion at about 100 m; (2) appreciable nitrate drawdowns throughout the upper 20–40 m of the water column; (3) silicic acid depletions during the summer in the surface waters, which were largest at the western end of the study area; (4) an increase in TA largely due to the loss of NO 3 −; and (5) decreases in TCO 2 close to expected values for consumption of carbon and nitrogen in “Redfield” proportions. Consistent with previous observations, N, P and Si never approached limiting concentrations during any of the cruises

Does coping mediate the relationship between familism and caregiver outcomes?

noObjectives: The sociocultural model of stress and coping, which despite receiving support from several studies conducted with diverse ethnic groups, has yet to be tested longitudinally or used within the context of positive caregiver outcomes. The aim of the current study was to test a specific component of the model, which posits that caregiver coping will be influenced by the cultural value of familism (feelings of solidarity and loyalty among family members), which will in turn affect caregiver outcomes. Method: A questionnaire was completed by 123 family caregivers in the UK assessing familism, use of coping strategies, caregiver gains, anxiety and depression at three time points over nine months. Results: Mediation analysis followed guidelines proposed by Baron and Kenny. Religious coping and positive reframing at time 2 (T2) were found to significantly mediate between familism values at time 1 (T1) and caregiver gains at time 3 (T3). Behavioural disengagement at T2 was found to mediate between familism at T1 and caregiver depression atT3. Additionally familism was found to be positively associated with both negative and positive aspects of caregiving. Conclusion: Our longitudinal findings suggest that interventions and services acknowledging caregiver values and the associated coping responses may prove beneficial