Chemical Bonding in the C2_2 Molecule

Bonding in the C$_2$ molecule is investigated with CAS(8,8) wave functions using canonical MOs. In a subsequent step, orthogonal atomic orbitals are constructed by localizing the CASSCF MOs on the two carbon atoms with an orthogonal transformation. This orbital transformation causes an orthogonal transformation of the configuration state functions (CSF) spanning the function space of the singlet ground state of C$_2$. Instead of CSFs built from canonical MOs one gets CSFs of orthogonal deformed atomic orbitals (AO). This approach resembles the orthogonal valence bond methods (OVB) CSFs which are very different from conventional VB, based on non-orthogonal AOs. To get used to the different argumentation, the bonding situation in ethane (single bond), ethene (double bond), and the nitrogen molecule (triple bond) are also studied. The complex bonding situation in C$_2$ is caused by the possibility to excite an electron with spin flip from the doubly occupied 2s AO into the 2p subshell, the resulting high-spin $^5S_u$ state of the carbon atom allows for a better reduction of the Pauli repulsion. But the electron structure around the equilibrium distance does not allow to say that C$_2$ in its ground state has a double, or triple, or even a quadruple bond

Analysis of climate paths reveals potential limitations on species range shifts

Copyright © 2011 Blackwell Publishing Ltd/CNRSForecasts of species endangerment under climate change usually ignore the processes by which species ranges shift. By analysing the 'climate paths' that range shifts might follow, and two key range-shift processes--dispersal and population persistence--we show that short-term climatic and population characteristics have dramatic effects on range-shift forecasts. By employing this approach with 15 amphibian species in the western USA, we make unexpected predictions. First, inter-decadal variability in climate change can prevent range shifts by causing gaps in climate paths, even in the absence of geographic barriers. Second, the hitherto unappreciated trait of persistence during unfavourable climatic conditions is critical to species range shifts. Third, climatic fluctuations and low persistence could lead to endangerment even if the future potential range size is large. These considerations may render habitat corridors ineffectual for some species, and conservationists may need to consider managed relocation and augmentation of in situ populations.Portuguese Foundation for Science and Technolog

Niche syndromes, species extinction risks, and management under climate change

Copyright © 2013 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Trends in Ecology and Evolution. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Trends in Ecology and Evolution Vol. 28 (2013), DOI: 10.1016/j.tree.2013.05.010The current distributions of species are often assumed to correspond with the total set of environmental conditions under which species can persist. When this assumption is incorrect, extinction risk estimated from species distribution models can be misleading. The degree to which species can tolerate or even thrive under conditions found beyond their current distributions alters extinction risks, time lags in realizing those risks, and the usefulness of alternative management strategies. To inform these issues, we propose a conceptual framework within which empirical data could be used to generate hypotheses regarding the realized, fundamental, and ‘tolerance’ niche of species. Although these niche components have rarely been characterized over geographic scales, we suggest that this could be done for many plant species by comparing native, naturalized, and horticultural distributions.FCT (Fundação para a Ciência e a Tecnologia

Validation of a 5-zone-car-cabin model to predict the energy saving potentials of a battery electric vehicle’s HVAC system

This paper presents a 5-zone-car-cabin model which is able to simulate the car cabin’s thermal condition depending on several influencing parameters. This includes the solar radiation, to which special attention is paid in this paper. In addition, a generic methodology for parameter optimization considering measurements on a reference vehicle is presented. Thus, a very high degree of determination of the model was achieved. This paper is motivated by the impact of auxiliary loads on overall energy consumption in battery electric vehicles. The further use of the model is intended to calculate the energy saving potentials of the heating, ventilation, and air conditioning system by reducing or increasing the target interior temperature. This is necessary for a predictive control of secondary consumers

Late onset of Huntington's disease

Twenty-five patients with late-onset Huntington's disease were studied; motor impairment appeared at age 50 years or later. The average age at onset of chorea was 57.5 years, with an average age at diagnosis of 63.1 years. Approximately 25% of persons affected by Huntington's disease exhibit late onset. A preponderance of maternal transmission was noted in late-onset Huntington's disease. The clinical features resembled those of mid-life onset Huntington's disease but progressed more slowly. Neuropathological evaluation of two cases reveal less severe neuronal atrophy than for mid-life onset disease

Technology transfer of dynamic IT outsourcing requires security measures in SLAs

For the present efforts in dynamic IT outsourcing environments like Grid or Cloud computing security and trust are ongoing issues. SLAs are a proved remedy to build up trust in outsourcing relations. Therefore, it is necessary to determine whether SLAs can improve trust from the perspective of the outsourcing customer by integration of security measures. The conducted survey indicates that customers see SLAs as an approach to increase their level of trust in IT outsourcing partners. In addition, security measures in SLAs are of high relevance to support trust but not yet integrated appropriately. However, SLAs are very important for the technology transfer of eScience projects in Grid computing. Again, Grid based outsourcing of biomedical IT services requires security measures in SLAs. Thus, the technology transfer process of dynamic IT outsourcing infrastructures requires adequate SLAs in order to be successful