Coupled Cluster Studies of Ionization Potentials and Electron Affinities of Single-Walled Carbon Nanotubes.

In this paper, we apply equation-of-motion coupled cluster (EOM-CC) methods in the studies of the vertical ionization potentials (IPs) and electron affinities (EAs) for a series of single-walled carbon nanotubes (SWCNT). The EOM-CC formulations for IPs and EAs employing excitation manifolds spanned by single and double excitations (IP/EA-EOM-CCSD) are used to study the IPs and EAs of the SWCNTs as a function of the nanotube length. Several armchair nanotubes corresponding to C20nH20 models with n = 2-6 have been used in benchmark calculations. In agreement with previous studies, we demonstrate that the electronegativity of C20nH20 systems remains, to a large extent, independent of the nanotube length. We also compare IP/EA-EOM-CCSD results with those obtained with coupled cluster models with single and double excitations corrected by perturbative triples, CCSD(T), and density functional theory (DFT) using global and range-separated hybrid exchange-correlation functionals.

Contributions of VLDLR and LRP8 in the establishment of retinogeniculate projections.

BACKGROUND: Retinal ganglion cells (RGCs), the output neurons of the retina, project to over 20 distinct brain nuclei, including the lateral geniculate nucleus (LGN), a thalamic region comprised of three functionally distinct subnuclei: the ventral LGN (vLGN), the dorsal LGN (dLGN) and the intergeniculate leaflet (IGL). We previously identified reelin, an extracellular glycoprotein, as a critical factor that directs class-specific targeting of these subnuclei. Reelin is known to bind to two receptors: very-low-density lipoprotein receptor (VLDLR) and low-density lipoprotein receptor-related protein 8 (LRP8), also known as apolipoprotein E receptor 2 (ApoER2). Here we examined the roles of these canonical reelin receptors in retinogeniculate targeting. RESULTS: To assess the roles of VLDLR and LRP8 in retinogeniculate targeting, we used intraocular injections of fluorescently conjugated cholera toxin B subunit (CTB) to label all RGC axons in vivo. Retinogeniculate projections in mutant mice lacking either VLDLR or LRP8 appeared similar to controls; however, deletion of both receptors resulted in dramatic defects in the pattern of retinal innervation in LGN. Surprisingly, defects in vldlr(-/-);lrp8(-/-) double mutant mice were remarkably different than those observed in mice lacking reelin. First, we failed to observe retinal axons exiting the medial border of the vLGN and IGL to invade distant regions of non-retino-recipient thalamus. Second, an ectopic region of binocular innervation emerged in the dorsomedial pole of vldlr(-/-);lrp8(-/-) mutant dLGN. Analysis of retinal projection development, retinal terminal sizes and LGN cytoarchitecture in vldlr(-/-);lrp8(-/-) mutants, all suggest that a subset of retinal axons destined for the IGL are misrouted to the dorsomedial pole of dLGN in the absence of VLDLR and LRP8. Such mistargeting is likely the result of abnormal migration of IGL neurons into the dorsomedial pole of dLGN in vldlr(-/-);lrp8(-/-) mutants. CONCLUSIONS: In contrast to our expectations, the development of both the LGN and retinogeniculate projections appeared dramatically different in mutants lacking either reelin or both canonical reelin receptors. These results suggest that there are reelin-independent functions of VLDLR and LRP8 in LGN development, and VLDLR- and LRP8-independent functions of reelin in class-specific axonal targeting.

The power of the National Surgical Quality Improvement Program--achieving a zero pneumonia rate in general surgery patients.

The National Surgical Quality Improvement Program (NSQIP) of the American College of Surgeons provides risk-adjusted surgical outcome measures for participating hospitals that can be used for performance improvement of surgical mortality and morbidity. A surgical clinical nurse reviewer collects 135 clinical variables including preoperative risk factors, intraoperative variables, and 30-day postoperative mortality and morbidity outcomes for patients undergoing major surgical procedures. A report on mortality and complications is prepared twice a year. This article summarizes briefly the history of NSQIP and how its report on surgical outcomes can be used for performance improvement within a hospital system. In particular, it describes how to drive performance improvement with NSQIP data using the example of postoperative respiratory complications--a major factor of postoperative mortality. In addition, this article explains the benefit of a collaborative of several participating NSQIP hospitals and describes how to develop a "playbook" on the basis of an outcome improvement project.