Kaon Energies in Dense Matter

We discuss the role of kaon-nucleon and nucleon-nucleon correlations in kaon condensation in dense matter. Correlations raise the threshold density for kaon condensation, possibly to densities higher than those encountered in stable neutron stars.Comment: RevTeX, 11 pages, 2 PostScript figures; manuscript also available, in PostScript form, at http://www.nordita.dk/locinfo/preprints.htm

On Neutrino Emission From Dense Matter Containing Meson Condensates

We consider the rate at which energy is emitted by neutrinos from the dense interior of neutron stars containing a Bose condensate of pions or kaons. The rates obtained are larger, by a factor of 2, than those found earlier, and are consistent with those found for the direct Urca processes.Comment: RevTeX, 10 page

Kaon Zero-Point Fluctuations in Neutron Star Matter

We investigate the contribution of zero-point motion, arising from fluctuations in kaon modes, to the ground state properties of neutron star matter containing a Bose condensate of kaons. The zero-point energy is derived via the thermodynamic partition function, by integrating out fluctuations for an arbitrary value of the condensate field. It is shown that the vacuum counterterms of the chiral Lagrangian ensure the cancellation of divergences dependent on $\mu$, the charge chemical potential, which may be regarded as an external vector potential. The total grand potential, consisting of the tree-level potential, the zero-point contribution, and the counterterm potential, is extremized to yield a locally charge neutral, beta-equilibrated and minimum energy ground state. In some regions of parameter space we encounter the well-known problem of a complex effective potential. Where the potential is real and solutions can be obtained, the contributions from fluctuations are found to be small in comparison with tree-level contributions.Comment: 40 pages RevTeX, 3 epsf figure

Kaon Condensation in the Bound-State Approach to the Skyrme Model

We explore kaon condensation using the bound-state approach to the Skyrme model on a 3-sphere. The condensation occurs when the energy required to produce a $K^-$ falls below the electron fermi level. This happens at the baryon number density on the order of 3--4 times nuclear density.Comment: LaTeX format, 15 pages. 3 Postscript figures, compressed and uuencode

State and Transition Models in Space and Time – Using STMs to Understand Broad Patterns of Ecosystem Change in Iceland

Managing ecological systems sustainably requires a deep understanding of ecosystem structure and the processes driving their dynamics. Conceptual models can lead to improved management, by providing a framework for organizing knowledge about a system and identifying the causal agents of change. We developed state-and-transition models (STMs) to describe landscape changes in Iceland over three historical periods with different human influence, from pre-settlement to present days. Our models identified the set of possible states, transitions and thresholds in these ecosystems and their changes over time. To illustrate the use of these models for predicting and improving management interventions, we applied our present-day STM to a case study in the central highlands of Iceland and monitored ecosystem changes within an ongoing field experiment with two management interventions (grazing exclusion and fertilization) in areas experiencing contrasting stages of degradation. The results of the experiment broadly align with the predictions of the model and underscore the importance of conceptual frameworks for adaptive management, where the best available knowledge is used to continuously refine and update the models

Similar decline in mortality rate of older persons with and without type 2 diabetes between 1993 and 2004 the Icelandic population-based Reykjavik and AGES-Reykjavik cohort studies.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Files. This article is open access.A decline in mortality rates due to cardiovascular diseases and all-cause mortality has led to increased life expectancy in the Western world in recent decades. At the same time, the prevalence of type 2 diabetes, a disease associated with a twofold excess risk of cardiovascular disease and mortality, has been increasing. The objective of this study was to estimate the secular trend of cardiovascular and all-cause mortality rates in two population-based cohorts of older persons, with and without type 2 diabetes, examined 11 years apart.1506 participants (42% men) from the population-based Reykjavik Study, examined during 1991-1996 (median 1993), mean age 75.0 years, and 4814 participants (43% men) from the AGES-Reykjavik Study, examined during 2002-2006 (median 2004), mean age 77.2 years, age range in both cohorts 70-87 years. The main outcome measures were age-specific mortality rates due to cardiovascular disease and all causes, over two consecutive 5.7- and 5.3-year follow-up periods.A 32% decline in cardiovascular mortality rate and a 19% decline in all-cause mortality rate were observed between 1993 and 2004. The decline was greater in those with type 2 diabetes, as illustrated by the decline in the adjusted hazard ratio of cardiovascular mortality in individuals with diabetes compared to those without diabetes, from 1.88 (95% CI 1.24-2.85) in 1993 to 1.46 (95% CI 1.11-1.91) in 2004. We also observed a concurrent decrease in major cardiovascular risk factors in both those with and without diabetes. A higher proportion of persons with diabetes received glucose-lowering, hypertensive and lipid-lowering medication in 2004.A decline in cardiovascular and all-cause mortality rates was observed in older persons during the period 1993-2004, in both those with and without type 2 diabetes. This decline may be partly explained by improvements in cardiovascular risk factors and medical treatment over the period studied. However, type 2 diabetes still persists as an independent risk factor for cardiovascular mortality.National Institute of Health/N01-AG-1-2100 NIA Intramural Research Program Icelandic Heart Association (Hjartavernd) Icelandic Parliament (Althingi

Rapid cooling of magnetized neutron stars

The neutrino emissivities resulting from direct URCA processes in neutron stars are calculated in a relativistic Dirac-Hartree approach in presence of a magnetic field. In a quark or a hyperon matter environment, the emissivity due to nucleon direct URCA processes is suppressed relative to that from pure nuclear matter. In all the cases studied, the magnetic field enhances emissivity compared to the field-free cases.Comment: 9 pages; Revtex; figure include

Kaon Condensation and Dynamical Nucleons in Neutron Stars

We discuss the nature of the kaon condensation phase transition. We find several features which, if kaons condense in neutron stars, are not only remarkable, but must surely effect such properties as superfluidity and transport properties, which in turn are relevant to the glitch phenomenon and cooling rates of neutron stars. The mixed phase, because of the extensive pressure range that it spans, will occupy a broad radial extent in a neutron star. This region is permeated with microscopic drops (and other configurations) located at lattice sites of one phase immersed in the background of the other phase. The electric charge on drops is opposite to that of the background phase {\sl and} nucleons have a mass approximately a factor two different depending on whether they are in the drops or the background phase. A large part of the stellar interior has this highly non-homogeneous structure.Comment: 5 pages, 6 figures, revtex. Physical Review Letters (accepted

Effects of statin medication on mortality risk associated with type 2 diabetes in older persons: the population-based AGES-Reykjavik Study

To access publisher full text version of this article. Please click on the hyperlink in Additional Links field.OBJECTIVE: To examine if the beneficial effect of statin medication on mortality seen in randomised clinical trials of type 2 diabetes applies equally to observational studies in the general population of older people. DESIGN: A prospective, population-based cohort study. SETTING: Reykjavik, Iceland. PARTICIPANTS: 5152 men and women from the Age, Gene/Environment Susceptibility-Reykjavik Study, mean age 77 years, range of 66-96 years. MAIN OUTCOME MEASURE: Cardiovascular and all-cause mortalities and the RR of dying according to statin use and history of coronary heart disease (CHD) in persons with type 2 diabetes and those without diabetes with a median follow-up time of 5.3 years, until end of 2009. RESULTS: The prevalence of type 2 diabetes was 12.4% of which 35% used statins. Statin use was associated with a 50% (95% CI 8% to 72%) lower cardiovascular mortality and 53% (29% to 68%) lower all-cause mortalities in persons with diabetes. For those without diabetes, statin use was associated with a 16% (-24% to 43%) lower cardiovascular and 30% (11% to 46%) lower all-cause mortalities. Persons with diabetes using statins had a comparable risk of cardiovascular and all-cause mortality to that of the general population without diabetes. The effect was independent of the level of glycaemic control. CONCLUSION: This observational study lends important support to existing data from randomised clinical trials. These data suggest that in the general population of older people with diabetes, statin medication markedly reduces the excess cardiovascular and all-cause mortality risk, irrespective of the presence or absence of coronary heart disease or glucose-lowering medication

In-medium meson properties and field transformations

Since the existing calculations of the effective meson mass in nuclear medium involve approximations, it is important to examine whether they satisfy the general requirement of the equivalence theorem that the physical observables should be independent of the choice of field variables. We study here consequences of nucleon field transformations. As an illustrative case we consider the in-medium effective pion mass calculated for the s-wave pion-nucleon interaction in the linear density approximation. We demonstrate that it is necessary to include the Born term explicitly in order that the effective pion mass should obey the equivalence theorem.Comment: 10 pages, using RevTeX4. More detailed discussion, references added. To be published in Phys. Rev.