On Effective Degrees of Freedom in the Early Universe

We explore the effective degrees of freedom in the early universe, from before the electroweak scale at a few femtoseconds after the Big Bang, until the last positrons disappeared a few minutes later. We first look at the established concepts of effective degrees of freedom for energy density, pressure and entropy density, and introduce effective degrees of freedom for number density as well. We discuss what happens with particle species as their temperature cools down from relativistic to semi- and non-relativistic temperatures, and then annihilates completely. This will affect the pressure as well as the entropy per particle. We also look at the transition from a quark-gluon plasma to a hadron gas. Using a list of known hadrons, we use a "cross-over" temperature of 214 MeV where the effective degrees of freedom for a quark-gluon plasma equals that of a hadron gas.Comment: 29 pages, 7 figure

State-of-the-art research : reflections on a concerted Nordic-Baltic nuclear energy effort

Quite a few hold the view that nuclear energy will have its renaissance in the not too distant future. Technology is, however, a necessary, but not sufficient condition. The needed prerequisites represent a complex issue. With increasing energy demand and depletion of non-renewable energy resources, nuclear will have to prove its role in an increasing energy mix, globally, regionally and often also nationally. Based on its history, experience with coordinated interplay in electricity production from a variety of energy sources, and science engagements, we argue for a future Nordic/Baltic SHOW CASE: A nuclear weapons free and proliferation safe nuclear energy supplier in the region, with a concerted role in competence building and in international ventures, and with focus on operation, safety economy and societal aspects

Viscous Phenomena and Entropy Production in the Early Universe

During the very first fraction of a second after the Big Bang, the Universe were populated by all the particles in the Standard Model of elementary particles: From the massive top quark to the massless photons and gluons. At very high temperatures all these particles were produced and annihilated at the same rate, and there were as many of one particle type as the next. As the creation of the massive particles requires high temperature, this would not last. One of my papers addresses the degrees of freedom related to the elementary particles, and show the evolution of these as the universe expands and cools. As the temperature decreases the particles will go from relativistic velocities to semi- and non-relativistic velocities, before finally disappearing. The temperature at which this happens depends on the particles masses. One important difference between relativistic and non-relativistic particles is that they cool at different rates. If we have a mixture of both types a bulk viscous effect will arise, resulting a heat transfer between the two components. Bulk viscosity and entropy production are at their highest at the end of the lepton era, just before the neutrinos decouple. At this time the neutrinos have a very long mean free path, resulting in large momentum transfers and heat exchange. The lepton era were a stage when Universe consisted of electrons, positrons, neutrinos, and photons. At higher temperatures, hadrons and eventually quarks and gluons make up a significant contribution. I have made a model universe where all particles except the leptons and photon are excluded. I can thus include the heavier cousins of the electron --- the muon and tau. By doing this, we get a more qualitative picture of what happens as particle species goes from relativistic velocities to semi- and non-relativistic temperatures and finally disappears one by one

Associations between quality of work features in primary health care and glycaemic control in people with Type 2 diabetes mellitus : A nationwide survey.

Aims: To describe and analyse the associations between primary health care centres’ (PHCCs’) quality of work (QOW) and individual HbA1c levels in people with Type 2 diabetes mellitus (T2DM). Methods: This cross-sectional study invited all 1152 Swedish PHCCs to answer a questionnaire addressing QOW conditions. Clinical, socio-economic and comorbidity data for 230,958 people with T2DM were linked to data on QOW conditions for 846 (73.4%) PHCCs. Results: Of the participants, 56% had controlled (≤52 mmol/mol), 31.9% intermediate (53–69 mmol/mol), and 12.1% uncontrolled (≥70 mmol/mol) HbA1c. An explanatory factor analysis identified seven QOW features. The features having a call-recall system, having individualized treatment plans, PHCCs’ results always on the agenda, and having a follow-up strategy combined with taking responsibility of outcomes/results were associated with lower HbA1c levels in the controlled group (all p < 0.05). For people with intermediate or uncontrolled HbA1c, having individualized treatment plans was the only QOW feature that was significantly associated with a lower HbA1c level (p < 0.05). Conclusions: This nationwide study adds important knowledge regarding associations between QOW in real life clinical practice and HbA1c levels. PHCCs’ QOW may mainly only benefit people with controlled HbA1c and more effective QOW strategies are needed to support people with uncontrolled HbA1c