Heat Pump with Two Heat Sources on Different Temperature Levels

Aim of the project is the development of a new heat pump system with economizing that is able to improve the heating performance using two or more different heat sources. These heat sources preferably on different temperature levels are incorporated in the system with minimal loss of exergy, by adding the heat at different pressure levels. Applications are i.e. buildings with heat pump and a solar thermal collector. While solar thermal systems can be used for heating and domestic hot water in summer, they fail to produce sufficient temperatures in fall and spring. When the solar collectors are also connected to the heat pump, they are able to supply temperatures higher than ambient at a medium temperature level. This heat at medium temperature can be used to improve the efficiency of an air source heat pump using the here proposed cycle. Existing systems using two heat sources are either inefficient or need large amounts of waste heat, while the proposed cycle can also use very small amounts of waste heat up to 40% of the total heat input. Other heat sources like process waste heat or exhaust air from a building are possible. Depending on the amount of waste heat and the temperature level of the heat pump cycle, efficiency and heating capacity improvements of 20-30% are possible. Oil management and control of the system are the main challenges when implementing it in the field. The paper will present the idea of the new cycle and its application in heat pump and refrigeration systems together with simulation results that show the effects of different parameters

Extended parental provisioning and variation in vertebrate brain sizes

Large brains provide adaptive cognitive benefits but require unusually high, near-constant energy inputs and become fully functional well after their growth is completed. Consequently, young of most larger-brained endotherms should not be able to independently support the growth and development of their own brains. This paradox is solved if the evolution of extended parental provisioning facilitated brain size evolution. Comparative studies indeed show that extended parental provisioning coevolved with brain size and that it may improve immature survival. The major role of extended parental provisioning supports the idea that the ability to sustain the costs of brains limited brain size evolution

Why big brains? A comparison of models for both primate and carnivore brain size evolution

Despite decades of research, much uncertainty remains regarding the selection pressures responsible for brain size variation. Whilst the influential social brain hypothesis once garnered extensive support, more recent studies have failed to find support for a link between brain size and sociality. Instead, it appears there is now substantial evidence suggesting ecology better predicts brain size in both primates and carnivores. Here, different models of brain evolution were tested, and the relative importance of social, ecological, and life-history traits were assessed on both overall encephalisation and specific brain regions. In primates, evidence is found for consistent associations between brain size and ecological factors, particularly diet; however, evidence was also found advocating sociality as a selection pressure driving brain size. In carnivores, evidence suggests ecological variables, most notably home range size, are influencing brain size; whereas, no support is found for the social brain hypothesis, perhaps reflecting the fact sociality appears to be limited to a select few taxa. Life-history associations reveal complex selection mechanisms to be counterbalancing the costs associated with expensive brain tissue through extended developmental periods, reduced fertility, and extended maximum lifespan. Future studies should give careful consideration of the methods chosen for measuring brain size, investigate both whole brain and specific brain regions where possible, and look to integrate multiple variables, thus fully capturing all of the potential factors influencing brain size

Hibernation constrains brain size evolution in mammals

The expensive brain hypothesis predicts that the lowest stable level of steady energy input acts as a strong constraint on a species’ brain size, and thus, that periodic troughs in net energy intake should select for reduced brain size relative to body mass. Here, we test this prediction for the extreme case of hibernation. Hibernators drastically reduce food intake for up to several months and are therefore expected to have smaller relative brain sizes than nonhibernating species. Using a comparative phylogenetic approach on brain size estimates of 1104 mammalian species, and controlling for possible confounding variables, we indeed found that the presence of hibernation in mammals is correlated with decreased relative brain size. This result adds to recent comparative work across mammals and amphibians supporting the idea that environmental seasonality (where in extremis hibernation is necessary for survival) imposes an energetic challenge and thus acts as an evolutionary constraint on relative brain size

National nitrogen budget for Germany

Emissions of reactive nitrogen (N-r) give rise to a wide range of environmental problems. Nitrogen budgets for various systems and on different scales are an established tool to quantify the sources and fate of N-r. The national nitrogen budget (NNB) for Germany calculates the nitrogen flows for eight pools: Atmosphere, Energy and Fuels, Material and Products in Industry, Humans and Settlements, Agriculture, Forest and Semi-natural Vegetation, Waste, and Hydrosphere, as well as for the transboundary N-flows. In Germany, in total 6,275 kt N-r a(-1) has been introduced into the nitrogen cycle annually (mean 2010 to 2014), of which 43% stem from ammonia synthesis. Domestic extraction and import of nitrogenous fossil fuels (lignite, coal, crude oil) releases another 2,335 kt N-r a(-1). Import of food, feed and materials contributes 745 kt N-r a(-1), while biological N fixation converts 308 kt N-r a(-1) into organically bound nitrogen. In terms of N-r sinks, the combustion and denoxing of fuels and the refining of crude oil converts 2,594 kt N-r a(-1) to N-2. In waters, soils, and wastewater treatment plants, denitrification leads to the release of 1,107 kt N-r a(-1) as N-2. Via the atmosphere and hydrosphere, Germany exports 755 kt N-r a(-1) to neighbouring countries and into coastal waters. On balance, Germany releases 1,627 kt N-r a(-1) annually to the environment. However, the NNB as a whole and the individual pool balances involve substantial uncertainties, which have to be considered when interpreting the results

Fatal Infection of a Pet Monkey with Human herpesvirus 1

Concerns have been raised about pet monkeys as a potential threat to humans. We report the opposite situation, a danger to pets that arises from humans. Similar to herpesvirus B (Cercopithecine herpesvirus 1), which endangers humans but not its host species, Human herpesvirus 1 can act as a “killer virus” when crossing the species barrier to New World monkeys