Information content of colored motifs in complex networks

We study complex networks in which the nodes of the network are tagged with different colors depending on the functionality of the nodes (colored graphs), using information theory applied to the distribution of motifs in such networks. We find that colored motifs can be viewed as the building blocks of the networks (much more so than the uncolored structural motifs can be) and that the relative frequency with which these motifs appear in the network can be used to define the information content of the network. This information is defined in such a way that a network with random coloration (but keeping the relative number of nodes with different colors the same) has zero color information content. Thus, colored motif information captures the exceptionality of coloring in the motifs that is maintained via selection. We study the motif information content of the C. elegans brain as well as the evolution of colored motif information in networks that reflect the interaction between instructions in genomes of digital life organisms. While we find that colored motif information appears to capture essential functionality in the C. elegans brain (where the color assignment of nodes is straightforward) it is not obvious whether the colored motif information content always increases during evolution, as would be expected from a measure that captures network complexity. For a single choice of color assignment of instructions in the digital life form Avida, we find rather that colored motif information content increases or decreases during evolution, depending on how the genomes are organized, and therefore could be an interesting tool to dissect genomic rearrangements.Comment: 21 pages, 8 figures, to appear in Artificial Lif

Structure and Dynamics of the VAULT COMPLEX

Vaults are the largest ribonucleoprotein particles found in eukaryotic cells. The maincomponent of these 13 MDa structures is the Mr 100,000 major vault protein (MVP).In mammalian cells, about 96 copies of this protein are necessary to form one vaultparticle. Two additional proteins are associated with the complex, the so-called minorvault proteins of Mr 193,000 (VPARP) and Mr 240,000 (TEP1), as well as severaluntranslated RNA molecules of 86-141 bases. The components are arranged into ahollow barrel-like structure with each half representing eight arches, which are reminiscent to the arched vaulted ceilings of cathedrals. Therefore, when vaults werefirst observed as contaminants in a preparation of clathrin coated vesicles form rat liver,the large complexes were named ‘vaults’. The typical morphology and the individualvault constituents appear conserved throughout evolution, implying an important rolefor vaults in cellular metabolism. A number of functions have been suggested for theseunique particles, but the general idea is that vaults function in intracellular transportprocesses. Nevertheless, the precise cellular function of the vault complex has not yetbeen elucidated. In this study we attempted to gain insight in vault biogenesis,dynamics and their interaction with other cellular components in order to unravel thephysiological significance of vault

Correlated fluctuations in the exciton dynamics and spectroscopy of DNA

The absorption of ultraviolet light creates excitations in DNA, which subsequently start moving in the helix. Their fate is important for an understanding of photo damage, and is determined by the interplay of electronic couplings between bases and the structure of the DNA environment. We model the effect of dynamical fluctuations in the environment and study correlation, which is present when multiple base pairs interact with the same mode in the environment. We find that the correlations strongly affect the exciton dynamics, and show how they are observed in the decay of the anisotropy as a function of a coherence and a population time in a non-linear optical experiment

Myotonic dystrophy: The burden for patients and their partners

Objective: Dystrophia myotonica is characterized by progressive muscular weakness, myotonia, mental slowness and lack of initiative, which causes problems in daily life both for patients and for their spouses. Some couples seem to deal with these problems satisfactorily, while for others they are quite burdensome. The aim of this study was to describe the relationship of severity of dystrophia myotonica and psychological wellbeing in patients and partners. Methods: Sixty-nine couples, in whom one partner had dystrophia myotonica, completed questionnaires on severity of dystrophia myotonica, marital satisfaction, anxiety and depression (Hospital Anxiety and Depression Scale), hopelessness (Beck Hopelessness Scale) and general psychological health (General Health Questionnaire-12). Results: For patients, a worse view of the future, worse general wellbeing, more anxiety and more depression was associated with a greater need for help. For partners, worse general wellbeing and more anxiety was associated with a lack of initiative of the patient and less marital satisfaction. It is noteworthy that 40% of patients and particularly female partners had Beck Hopelessness Scale scores suggestive of clinically relevant depression. Conclusion: Dystrophia myotonica places a heavy burden on patients, and especially on female partners. The need for help and dependency has more influence on the wellbeing of patients than the symptoms of dystrophia myotonica themselves. Marital satisfaction is a strong predictor of better wellbeing, both for patients and, even more so, for partners

Electromagnetic and mechanical characteristaion of ITER CS-MC conductors affected by transverse cyclic loading, part 3: mechanical properties

The magnetic field and current of a coil wound with a cable-in-conduit conductor causes a transverse force pushing the cable to one side of the conduit. This load causes elastic and plastic deformation with friction as well as heating due to friction. A special cryogenic press has been built to study the mechanical and electrical properties of full-size ITER conductors under transverse mechanical loading. The cryogenic press can transmit at 4.2 K cyclic forces of 650 kN/m to conductor sections of 400 mm length representative of the peak load on a 50 kA conductor at 13 T. In order to transmit the force directly onto the cable, the conduit is opened partly to allow the cable deformation. The force acting on the cable as well as the displacement are monitored simultaneously in order to determine the mechanical heat generation due to friction. The mechanical loss under load is investigated for the Nb3Sn, 45 kA, 10 and 13 T, central solenoid model cell conductors (CSMC). The mechanical heat generation is determined from the hysteresis in the measured curves of displacement versus applied force. The first results of the effect of some 40 loading cycles are presented and the two conductors are compared. A significant decrease of the cable mechanical heat generation after loading cycles is observed

Grains and grain boundaries in highly crystalline monolayer molybdenum disulfide

Recent progress in large-area synthesis of monolayer molybdenum disulfide, a new two-dimensional direct-bandgap semiconductor, is paving the way for applications in atomically thin electronics. Little is known, however, about the microstructure of this material. Here we have refined chemical vapor deposition synthesis to grow highly crystalline islands of monolayer molybdenum disulfide up to 120 um in size with optical and electrical properties comparable or superior to exfoliated samples. Using transmission electron microscopy, we correlate lattice orientation, edge morphology, and crystallinity with island shape to demonstrate that triangular islands are single crystals. The crystals merge to form faceted tilt and mirror boundaries that are stitched together by lines of 8- and 4- membered rings. Density functional theory reveals localized mid-gap states arising from these 8-4 defects. We find that mirror boundaries cause strong photoluminescence quenching while tilt boundaries cause strong enhancement. In contrast, the boundaries only slightly increase the measured in-plane electrical conductivity