Probabilistic Analysis and Design of a Raked Wing Tip for a Commercial Transport

An approach for conducting reliability-based design and optimization (RBDO) of a Boeing 767 raked wing tip (RWT) is presented. The goal is to evaluate the benefits of RBDO for design of an aircraft substructure. A finite-element (FE) model that includes eight critical static load cases is used to evaluate the response of the wing tip. Thirteen design variables that describe the thickness of the composite skins and stiffeners are selected to minimize the weight of the wing tip. A strain-based margin of safety is used to evaluate the performance of the structure. The randomness in the load scale factor and in the strain limits is considered. Of the 13 variables, the wing-tip design was controlled primarily by the thickness of the thickest plies in the upper skins. The report includes an analysis of the optimization results and recommendations for future reliability-based studies

Direct grafting of tetraaniline via perfluorophenylazide photochemistry to create antifouling, low bio-adhesion surfaces.

Conjugated polyaniline has shown anticorrosive, hydrophilic, antibacterial, pH-responsive, and pseudocapacitive properties making it of interest in many fields. However, in situ grafting of polyaniline without harsh chemical treatments is challenging. In this study, we report a simple, fast, and non-destructive surface modification method for grafting tetraaniline (TANI), the smallest conjugated repeat unit of polyaniline, onto several materials via perfluorophenylazide photochemistry. The new materials are characterized by nuclear magnetic resonance (NMR) and electrospray ionization (ESI) mass spectroscopy. TANI is shown to be covalently bonded to important carbon materials including graphite, carbon nanotubes (CNTs), and reduced graphene oxide (rGO), as confirmed by transmission electron microscopy (TEM). Furthermore, large area modifications on polyethylene terephthalate (PET) films through dip-coating or spray-coating demonstrate the potential applicability in biomedical applications where high transparency, patternability, and low bio-adhesion are needed. Another important application is preventing biofouling in membranes for water purification. Here we report the first oligoaniline grafted water filtration membranes by modifying commercially available polyethersulfone (PES) ultrafiltration (UF) membranes. The modified membranes are hydrophilic as demonstrated by captive bubble experiments and exhibit extraordinarily low bovine serum albumin (BSA) and Escherichia coli adhesions. Superior membrane performance in terms of flux, BSA rejection and flux recovery after biofouling are demonstrated using a cross-flow system and dead-end cells, showing excellent fouling resistance produced by the in situ modification

Exact Results for Wilson Loops in Superconformal Chern-Simons Theories with Matter

We use localization techniques to compute the expectation values of supersymmetric Wilson loops in Chern-Simons theories with matter. We find the path-integral reduces to a non-Gaussian matrix model. The Wilson loops we consider preserve a single complex supersymmetry, and exist in any N=2 theory, though the localization requires superconformal symmetry. We present explicit results for the cases of pure Chern-Simons theory with gauge group U(N), showing agreement with the known results, and ABJM, showing agreement with perturbative calculations. Our method applies to other theories, such as Gaiotto-Witten theories, BLG, and their variants.Comment: 32 page

Ecosystem carbon 7 dioxide fluxes after disturbance in forests of North America

Disturbances are important for renewal of North American forests. Here we summarize more than 180 site years of eddy covariance measurements of carbon dioxide flux made at forest chronosequences in North America. The disturbances included stand-replacing fire (Alaska, Arizona, Manitoba, and Saskatchewan) and harvest (British Columbia, Florida, New Brunswick, Oregon, Quebec, Saskatchewan, and Wisconsin) events, insect infestations (gypsy moth, forest tent caterpillar, and mountain pine beetle), Hurricane Wilma, and silvicultural thinning (Arizona, California, and New Brunswick). Net ecosystem production (NEP) showed a carbon loss from all ecosystems following a stand-replacing disturbance, becoming a carbon sink by 20 years for all ecosystems and by 10 years for most. Maximum carbon losses following disturbance (g C m−2y−1) ranged from 1270 in Florida to 200 in boreal ecosystems. Similarly, for forests less than 100 years old, maximum uptake (g C m−2y−1) was 1180 in Florida mangroves and 210 in boreal ecosystems. More temperate forests had intermediate fluxes. Boreal ecosystems were relatively time invariant after 20 years, whereas western ecosystems tended to increase in carbon gain over time. This was driven mostly by gross photosynthetic production (GPP) because total ecosystem respiration (ER) and heterotrophic respiration were relatively invariant with age. GPP/ER was as low as 0.2 immediately following stand-replacing disturbance reaching a constant value of 1.2 after 20 years. NEP following insect defoliations and silvicultural thinning showed lesser changes than stand-replacing events, with decreases in the year of disturbance followed by rapid recovery. NEP decreased in a mangrove ecosystem following Hurricane Wilma because of a decrease in GPP and an increase in ER

Surgical intervention for complications caused by femoral artery catheterization in pediatric patients

AbstractPurpose: This study evaluated the risk factors and surgical management of complications caused by femoral artery catheterization in pediatric patients. Methods: From January 1986 to March 2001, the hospital records of all children who underwent operative repairs for complications caused by femoral artery catheterization were reviewed. A prospective cardiac data bank containing 1674 catheterization procedures during the study period was used as a means of determining risk factors associated with iatrogenic femoral artery injury. Results: Thirty-six operations were performed in 34 patients (age range, 1 week-17.4 years) in whom iatrogenic complications developed after either diagnostic or therapeutic femoral artery catheterizations during the study period. Non-ischemic complications included femoral artery pseudoaneurysms (n = 4), arteriovenous fistulae (n = 5), uncontrollable bleeding, and expanding hematoma (n = 4). Operative repairs were performed successfully in all patients with non-ischemic iatrogenic femoral artery injuries. In contrast, ischemic complications occurred in 21 patients. Among them, 14 patients had acute femoral ischemia and underwent surgical interventions including femoral artery thrombectomy with primary closure (n = 6), saphenous vein patch angioplasty (n = 6), and resection with primary anastomosis (n = 2). Chronic femoral artery occlusion (> 30 days) occurred in seven patients, with symptoms including either severe claudication (n = 4) or gait disturbance or limb growth impairment (n = 3). Operative treatments in these patients included ileofemoral bypass grafting (n = 5), femorofemoral bypass grafting (n = 1), and femoral artery patch angioplasty (n = 1). During a mean follow-up period of 38 months, no instances of limb loss occurred, and 84% of children with ischemic complications eventually gained normal circulation. Factors that correlated with an increased risk of iatrogenic groin complications that necessitated surgical intervention included age younger than 3 years, therapeutic intervention, number of catheterizations (≥ 3), and use of 6F or larger guiding catheter. Conclusion: Although excellent operative results can be achieved in cases of non-ischemic complications, acute femoral occlusion in children younger than 2 years often leads to less satisfactory outcomes. Operative intervention can provide successful outcome in children with claudication caused by chronic limb ischemia. Variables that correlated with significant iatrogenic groin complications included a young age, therapeutic intervention, earlier catheterization, and the use of a large guiding catheter. (J Vasc Surg 2001;33:1071-8.

A Pseudomonas syringae pv. tomato DC3000 mutant lacking the type III effector HopQ1-1 is able to cause disease in the model plant Nicotiana benthamiana

The model pathogen Pseudomonas syringae pv. tomato DC3000 causes bacterial speck in tomato and Arabidopsis, but Nicotiana benthamiana, an important model plant, is considered to be a non-host. Strain DC3000 injects approximately 28 effector proteins into plant cells via the type III secretion system (T3SS). These proteins were individually delivered into N. benthamiana leaf cells via T3SS-proficient Pseudomonas fluorescens, and eight, including HopQ1-1, showed some capacity to cause cell death in this test. Four gene clusters encoding 13 effectors were deleted from DC3000: cluster II (hopH1, hopC1), IV (hopD1, hopQ1-1, hopR1), IX (hopAA1-2, hopV1, hopAO1, hopG1), and native plasmid pDC3000A (hopAM1-2, hopX1, hopO1-1, hopT1-1). DC3000 mutants deleted for cluster IV or just hopQ1-1 acquired the ability to grow to high levels and produce bacterial speck lesions in N. benthamiana. HopQ1-1 showed other hallmarks of an avirulence determinant in N. benthamiana: expression in the tobacco wildfire pathogen P. syringae pv. tabaci 11528 rendered this strain avirulent in N. benthamiana, and elicitation of the hypersensitive response in N. benthamiana by HopQ1-1 was dependent on SGT1. DC3000 polymutants involving other effector gene clusters in a hopQ1-1-deficient background revealed that clusters II and IX contributed to the severity of lesion symptoms in N. benthamiana, as well as in Arabidopsis and tomato. The results support the hypothesis that the host ranges of P. syringae pathovars are limited by the complex interactions of effector repertoires with plant antieffector surveillance systems, and they demonstrate that N. benthamiana can be a useful model host for DC3000

A Pseudomonas syringae pv. tomato DC3000 mutant lacking the type III effector HopQ1-1 is able to cause disease in the model plant Nicotiana benthamiana

The model pathogen Pseudomonas syringae pv. tomato DC3000 causes bacterial speck in tomato and Arabidopsis, but Nicotiana benthamiana, an important model plant, is considered to be a non-host. Strain DC3000 injects approximately 28 effector proteins into plant cells via the type III secretion system (T3SS). These proteins were individually delivered into N. benthamiana leaf cells via T3SS-proficient Pseudomonas fluorescens, and eight, including HopQ1-1, showed some capacity to cause cell death in this test. Four gene clusters encoding 13 effectors were deleted from DC3000: cluster II (hopH1, hopC1), IV (hopD1, hopQ1-1, hopR1), IX (hopAA1-2, hopV1, hopAO1, hopG1), and native plasmid pDC3000A (hopAM1-2, hopX1, hopO1-1, hopT1-1). DC3000 mutants deleted for cluster IV or just hopQ1-1 acquired the ability to grow to high levels and produce bacterial speck lesions in N. benthamiana. HopQ1-1 showed other hallmarks of an avirulence determinant in N. benthamiana: expression in the tobacco wildfire pathogen P. syringae pv. tabaci 11528 rendered this strain avirulent in N. benthamiana, and elicitation of the hypersensitive response in N. benthamiana by HopQ1-1 was dependent on SGT1. DC3000 polymutants involving other effector gene clusters in a hopQ1-1-deficient background revealed that clusters II and IX contributed to the severity of lesion symptoms in N. benthamiana, as well as in Arabidopsis and tomato. The results support the hypothesis that the host ranges of P. syringae pathovars are limited by the complex interactions of effector repertoires with plant antieffector surveillance systems, and they demonstrate that N. benthamiana can be a useful model host for DC3000

The Spectrum of the Dirac Operator on Coset Spaces with Homogeneous Gauge Fields

The spectrum and degeneracies of the Dirac operator are analysed on compact coset spaces when there is a non-zero homogeneous background gauge field which is compatible with the symmetries of the space, in particular when the gauge field is derived from the spin-connection. It is shown how the degeneracy of the lowest Landau level in the recently proposed higher dimensional quantum Hall effect is related to the Atiyah-Singer index theorem for the Dirac operator on a compact coset space.Comment: 25 pages, typeset in LaTeX, uses youngtab.st

Checkerboard local density of states in striped domains pinned by vortices

Within a Green's function formalism we calculate the electronic structure around static extended magnetic and non-magnetic perturbations in a d-wave superconductor. In partucular, we discuss recent elastic neutron scattering and scanning tunneling experiments on High-T_c cuprates exposed to an applied magnetic field. A physical picture consisting of antiferromagnetic vortex cores operating as pinning centers for surrounding stripes is qualitatively consistent with the neutron data provided the stripes have the usual antiphase modulation. The low energy electronic structure in such a region reveals a checkerboard interference pattern consistent with recent scanning tunneling experiments.Comment: 5 pages, 4 figure

The “Soluble” Adenylyl Cyclase in Sperm Mediates Multiple Signaling Events Required for Fertilization

SummaryMammalian fertilization is dependent upon a series of bicarbonate-induced, cAMP-dependent processes sperm undergo as they “capacitate,” i.e., acquire the ability to fertilize eggs. Male mice lacking the bicarbonate- and calcium-responsive soluble adenylyl cyclase (sAC), the predominant source of cAMP in male germ cells, are infertile, as the sperm are immotile. Membrane-permeable cAMP analogs are reported to rescue the motility defect, but we now show that these “rescued” null sperm were not hyperactive, displayed flagellar angulation, and remained unable to fertilize eggs in vitro. These deficits uncover a requirement for sAC during spermatogenesis and/or epididymal maturation and reveal limitations inherent in studying sAC function using knockout mice. To circumvent this restriction, we identified a specific sAC inhibitor that allowed temporal control over sAC activity. This inhibitor revealed that capacitation is defined by separable events: induction of protein tyrosine phosphorylation and motility are sAC dependent while acrosomal exocytosis is not dependent on sAC