559 research outputs found
Expectation values of single-particle operators in the random phase approximation ground state
We developed a method for computing matrix elements of single-particle
operators in the correlated random phase approximation ground state. Working
with the explicit random phase approximation ground state wavefunction, we
derived practically useful and simple expression for a molecular property in
terms of random phase approximation amplitudes. The theory is illustrated by
the calculation of molecular dipole moments for a set of representative
molecules.Comment: Accepted to J.Chem.Phy
trans-1,2-Difluoro-3,4,5,6,7,8-hexaphenyltricyclo[4.2.0.0^(2,5)]octa-3,7-diene
In order to probe the possible mechanism of the rearrangement of trans-hexaphenyldifluorotricyclooctadiene (a dimer of fluorotriphenylcyclobutadiene) to pentaphenyldihydrodifluoropentalene via C-F bond migration, a high-temperature study of the title compound, C_(44)H_(30)F_2, was performed at 400 (2) K. In the title compound, there are three fused four-membered rings with the resulting eight-membered tricyclo¬octa¬diene ring adopting a sofa conformation. The dihedral angles between the central four-membered ring and the two outer rings are 66.03 (2) and 65.39 (2)°. The crystal structure contains centrosymmetric dimers formed by C-H… π inter¬actions
Intermittent Hypoxia-Induced Cognitive Deficits Are Mediated by NADPH Oxidase Activity in a Murine Model of Sleep Apnea
Background: In rodents, exposure to intermittent hypoxia (IH), a hallmark of obstructive sleep apnea (OSA), is associated with neurobehavioral impairments, increased apoptosis in the hippocampus and cortex, as well as increased oxidant stress and inflammation. Excessive NADPH oxidase activity may play a role in IH-induced CNS dysfunction. Methods and Findings: The effect of IH during light period on two forms of spatial learning in the water maze and well as markers of oxidative stress was assessed in mice lacking NADPH oxidase activity (gp91phox _/Y) and wild-type littermates. On a standard place training task, gp91phox _/Y displayed normal learning, and were protected from the spatial learning deficits observed in wild-type littermates exposed to IH. Moreover, anxiety levels were increased in wild-type mice exposed to IH as compared to room air (RA) controls, while no changes emerged in gp91phox _/Y mice. Additionally, wild-type mice, but not gp91phox _/Y mice had significantly elevated levels of NADPH oxidase expression and activity, as well as MDA and 8-OHDG in cortical and hippocampal lysates following IH exposures. Conclusions: The oxidative stress responses and neurobehavioral impairments induced by IH during sleep are mediated, at least in part, by excessive NADPH oxidase activity, and thus pharmacological agents targeting NADPH oxidase may provid
Regulation of ErbB2 Receptor Status by the Proteasomal DUB POH1
Understanding the factors, which control ErbB2 and EGF receptor (EGFR) status in cells is likely to inform future therapeutic approaches directed at these potent oncogenes. ErbB2 is resistant to stimulus-induced degradation and high levels of over-expression can inhibit EGF receptor down-regulation. We now show that for HeLa cells expressing similar numbers of EGFR and ErbB2, EGFR down-regulation is efficient and insensitive to reduction of ErbB2 levels. Deubiquitinating enzymes (DUBs) may extend protein half-lives by rescuing ubiquitinated substrates from proteasomal degradation or from ubiquitin-dependent lysosomal sorting. Using a siRNA library directed at the full complement of human DUBs, we identified POH1 (also known as Rpn11 or PSMD14), a component of the proteasome lid, as a critical DUB controlling the apparent ErbB2 levels. Moreover, the effects on ErbB2 levels can be reproduced by administration of proteasomal inhibitors such as epoxomicin used at maximally tolerated doses. However, the extent of this apparent loss and specificity for ErbB2 versus EGFR could not be accounted for by changes in transcription or degradation rate. Further investigation revealed that cell surface ErbB2 levels are only mildly affected by POH1 knock-down and that the apparent loss can at least partially be explained by the accumulation of higher molecular weight ubiquitinated forms of ErbB2 that are detectable with an extracellular but not intracellular domain directed antibody. We propose that POH1 may deubiquitinate ErbB2 and that this activity is not necessarily coupled to proteasomal degradation
Designing Hybrid Gifts
Hybrid gifting combines physical artefacts and experiences with digital interactivity to generate new kinds of gifts. Our review details how gifting is a complex social phenomenon and how digital gifting is less engaging than physical gifting for both givers and receivers. Employing a Research Through Design approach, we developed a portfolio of four hybrid gifting experiences: an augmented advent calendar; edible music tracks; personalised museum tours; and a narrated city walk. Our reflection addresses three concepts: hybrid wrapping where physical gifts become wrapped in digital media and vice versa; the importance of effortful interactions that are visible and pleasurable; and the need to consider social obligation, including opportunities for acknowledgement and reciprocation, dealing with embarrassment, and recognising the distinction between giving and sharing. Our concepts provide guidance to practitioners who wish to design future gifting experiences while helping HCI researchers engage with the concept of gifting in a nuanced way
SNW1 Is a Critical Regulator of Spatial BMP Activity, Neural Plate Border Formation, and Neural Crest Specification in Vertebrate Embryos
In frog and fish embryos, SNW1 is a protein required for the spatio-temporal activity of BMP signaling necessary for neural plate border formation and specification of neural crest tissue
Mitochondrial haplogroup N1a phylogeography, with implication to the origin of European farmers
<p>Abstract</p> <p>Background</p> <p>Tracing the genetic origin of central European farmer N1a lineages can provide a unique opportunity to assess the patterns of the farming technology spread into central Europe in the human prehistory. Here, we have chosen twelve N1a samples from modern populations which are most similar with the farmer N1a types and performed the complete mitochondrial DNA genome sequencing analysis. To assess the genetic and phylogeographic relationship, we performed a detailed survey of modern published N1a types from Eurasian and African populations.</p> <p>Results</p> <p>The geographic origin and expansion of farmer lineages related N1a subclades have been deduced from combined analysis of 19 complete sequences with 166 N1a haplotypes. The phylogeographic analysis revealed that the central European farmer lineages have originated from different sources: from eastern Europe, local central Europe, and from the Near East via southern Europe.</p> <p>Conclusions</p> <p>The results obtained emphasize that the arrival of central European farmer lineages did not occur via a single demic diffusion event from the Near East at the onset of the Neolithic spread of agriculture into Europe. Indeed these results indicate that the Neolithic transition process was more complex in central Europe and possibly the farmer N1a lineages were a result of a 'leapfrog' colonization process.</p
A Global Census of Fission Yeast Deubiquitinating Enzyme Localization and Interaction Networks Reveals Distinct Compartmentalization Profiles and Overlapping Functions in Endocytosis and Polarity
Proteomic, localization, and enzymatic activity screens in fission yeast reveal how deubiquitinating enzyme localization and function are tuned
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