Chimeras in the two-community Kuramoto model with an external drive

We study the bifurcations of a special case of the Kuramoto model with two communities of oscillators and an external drive. We use Ott-Antonsens ansatz to derive the low-dimensional system of differential equations that governs the macroscopic dynamics of the high-dimensional problem. The choice of parameters of the system is motivated by the search for so-called Chimera states; stable phase configurations with partial synchronization. Our main result is the derivation of the low-dimensional system following Ott-Antonsens Ansatz and findings of periodic and chaotic Chimeras

System reliability in the Nordic power market : a scenario analysis for 2030

This study assesses the effect a higher penetration of variable renewable energy (VRE) and a shutdown of Swedish Nuclear power will have on the reliability in the Nordic power market in 2030. A probabilistic model was used to predict the loss of load probability (LOLP) and expected unserved energy (EUE). The model includes time series for demand and capacity utilization of wind-, photovoltaic-, run of river hydro power and nuclear power production. Two scenarios were analysed; (1) base scenario with a predicted capacity mix with high shares of VRE and some decrease in nuclear power production compared to today’s capacities, and (2) complete shutdown of Sweden’s nuclear power production. Both scenarios where run with the assumption of a)import and b)no import from countries surrounding the Nordic power market. The most important findings are: • The scenario analysis shows that the Nordic power market is able to handle exposed situations in 2030 if Sweden keeps some of its nuclear production, todays planned expansion of interconnections with surrounding countries is realized and an assuming extensive development in wind power production. • A shutdown of Sweden’s power production will give a decrease in the reliability compared to a situation with nuclear power and be just short of a satisfactory level of adequacy with a LOLP requirement of 1‰. • The Nordic power market in 2030 cannot keep a satisfactory level of reliability without import from surrounding countries. The current reliability in the Nordic power market is strong, but increased shares of VRE combined with reduced nuclear power production and/or increased consumption will require increased flexibility to maintain a satisfactory level of reliability in 2030. Measures to increase the flexibility, like demand response and increased transmission capacity, as well as the effect of demanding cold/dry years on total hydro storage capacity should be analyzed in further studies.Denne studien undersøker effekten av en høyere andel variable fornybar energi og komplett utfasing av Sveriges kjernekraft vil ha på forsyningssikkerheten i Norden i 2030. En modell ble brukt til å beregne tap av last (LOLP) og tilhørende mengde ikke-levert energi. Modellen bruker tidsserier for forbruk og kapasitetsutnyttelse av vind-, sol-, uregulerbar vannkraft- og kjernekraftproduksjon. To scenarioer for kapasitetsmiks var analysert; 1) basisscenario med en høy andel variable fornybar kraftproduksjon og reduksjon i kjernekraftproduksjon, og 2) komplett utfasing av Sveriges kjernekraft, med antagelse om a)import fra omkringliggende land og b)ingen import. De viktigste funnene er: • Scenario analysen viser at forsyningssikkerheten i Norden i 2030 er god om Sverige beholder noe av sin kjernekraft og dagens planlagte utenlandskabler er realisert. • En total utfasing av Sveriges kjernekraft vil senke forsyningssikkerheten sammenlignet med et scenario med kjernekraft, og gi lavere LOLP-verdier enn et vanlig krav på 1‰. • Det nordiske energimarkedet kan ikke opprettholde et tilfredsstillende nivå på forsyningssikkerheten uten import fra omkringliggende land. Dagens forsyningssikkerhet er god, men økte andeler variabel fornybar kraftproduksjon kombinert med utfasing av kjernekraft og/eller økt forbruk vil kreve økt fleksibilitet for å opprettholde dette i 2030. Tiltak for for øke fleksibiliteten, som forburkerfleksibilitet og økt overføringskapasitet bør analyserer i videre studier.M-FORN

Evolutionary insights into premetazoan functions of the neuronal protein homer.

Reconstructing the evolution and ancestral functions of synaptic proteins promises to shed light on how neurons first evolved. The postsynaptic density (PSD) protein Homer scaffolds membrane receptors and regulates Ca(2+) signaling in diverse metazoan cell types (including neurons and muscle cells), yet its ancestry and core functions are poorly understood. We find that the protein domain organization and essential biochemical properties of metazoan Homer proteins, including their ability to tetramerize, are conserved in the choanoflagellate Salpingoeca rosetta, one of the closest living relatives of metazoans. Unlike in neurons, Homer localizes to the nucleoplasm in S. rosetta and interacts directly with Flotillin, a protein more commonly associated with cell membranes. Surprisingly, we found that the Homer/Flotillin interaction and its localization to the nucleus are conserved in metazoan astrocytes. These findings suggest that Homer originally interacted with Flotillin in the nucleus of the last common ancestor of metazoans and choanoflagellates and was later co-opted to function as a membrane receptor scaffold in the PSD

Control of heat pumps with CO2 emission intensity forecasts

An optimized heat pump control for building heating was developed for minimizing CO2 emissions from related electrical power generation. The control is using weather and CO2 emission forecasts as input to a Model Predictive Control (MPC) - a multivariate control algorithm using a dynamic process model, constraints and a cost function to be minimized. In a simulation study the control was applied using weather and power grid conditions during a full year period in 2017-2018 for the power bidding zone DK2 (East, Denmark). Two scenarios were studied; one with a family house and one with an office building. The buildings were dimensioned on the basis of standards and building codes. The main results are measured as the CO2 emission savings relative to a classical thermostatic control. Note that this only measures the gain achieved using the MPC control, i.e. the energy flexibility, not the absolute savings. The results show that around 16% savings could have been achieved during the period in well insulated new buildings with floor heating. Further, a sensitivity analysis was carried out to evaluate the effect of various building properties, e.g. level of insulation and thermal capacity. Danish building codes from 1977 and forward was used as benchmarks for insulation levels. It was shown that both insulation and thermal mass influence the achievable flexibility savings, especially for floor heating. Buildings that comply with codes later than 1979 could provide flexibility emission savings of around 10%, while buildings that comply with earlier codes provided savings in the range of 0-5% depending on the heating system and thermal mass.Comment: 16 pages, 12 figures. Submitted to Energie

A sandwich enzyme-linked immunosorbent assay for the quantification of insoluble membrane and scaffold proteins

AbstractEnzyme-linked immunosorbent assays (ELISAs) are applied for the quantification of a vast diversity of small molecules. However, ELISAs require that the antigen is present in a soluble form in the sample. Accordingly, the few ELISAs described so far targeting insoluble proteins such as integral membrane and scaffold proteins have been restricted by limited extraction efficiencies and the need to establish an individual solubilization protocol for each protein. Here we describe a sandwich ELISA that allows the quantification of a diverse array of synaptic membrane and scaffold proteins such as munc13-1, gephyrin, NMDA R1 (N-methyl-d-aspartate receptor subunit 1), synaptic vesicle membrane proteins, and SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors). The assay is based on initial solubilization by the denaturing detergent sodium dodecyl sulfate (SDS), followed by partial SDS removal using the detergent Triton X-100, which restores antigenicity while keeping the proteins in solution. Using recombinant standard proteins, we determined assay sensitivities of 78ng/ml to 77pg/ml (or 74–0.1fmol). Calibration of the assay using both immunoblotting and mass spectroscopy revealed that in some cases correction factors need to be included for absolute quantification. The assay is versatile, allows parallel processing and automation, and should be applicable to a wide range of hitherto inaccessible proteins

Characterization of two common 5' polymorphisms in PEX1 and correlation to survival in PEX1 peroxisome biogenesis disorder patients

<p>Abstract</p> <p>Background</p> <p>Mutations in PEX1 are the most common primary cause of Zellweger syndrome. In addition to exonic mutations, deletions and splice site mutations two 5' polymorphisms at c.-137 and c.-53 with a potential influence on PEX1 protein levels have been described in the 5' untranslated region (UTR) of the <it>PEX1 </it>gene.</p> <p>Methods</p> <p>We used RACE and in silico promoter prediction analysis to study the 5' UTR of <it>PEX1</it>. We determined the distribution of <it>PEX1 </it>5' polymorphisms in a cohort of 30 Zellweger syndrome patients by standard DNA sequencing. 5' polymorphisms were analysed in relation to the two most common mutations in <it>PEX1 </it>and were incorporated into a novel genotype-phenotype analysis by correlation of three classes of <it>PEX1 </it>mutations with patient survival.</p> <p>Results</p> <p>We provide evidence that the polymorphism 137 bp upstream of the ATG codon is not part of the UTR, rendering it a promoter polymorphism. We show that the first, but not the second most common <it>PEX1 </it>mutation arose independently of a specific upstream polymorphic constellation. By genotype-phenotype analysis we identified patients with identical exonic mutation and identical 5' polymorphisms, but strongly differing survival.</p> <p>Conclusions</p> <p>Our study suggests that two different types of <it>PEX1 </it>5' polymorphisms have to be distinguished: a 5' UTR polymorphism at position c.-53 and a promoter polymorphism 137 bp upstream of the PEX1 start codon. Our results indicate that the exonic <it>PEX1 </it>mutation correlates with patient survival, but the two 5' polymorphisms analysed in this study do not have to be considered for diagnostic and/or prognostic purposes.</p