Contact Topology and the Classification of Disclination Lines in Cholesteric Liquid Crystals.

We give a complete topological classification of defect lines in cholesteric liquid crystals using methods from contact topology. By focusing on the role played by the chirality of the material, we demonstrate a fundamental distinction between "tight" and "overtwisted" disclination lines not detected by standard homotopy theory arguments. The classification of overtwisted lines is the same as nematics, however, we show that tight disclinations possess a topological layer number that is conserved as long as the twist is nonvanishing. Finally, we observe that chirality frustrates the escape of removable defect lines, and explain how this frustration underlies the formation of several structures observed in experiments.

Layering transitions and metastable structures of cholesteric liquid crystals in cylindrical confinement.

Our study of cholesteric lyotropic chromonic liquid crystals in cylindrical confinement reveals the topological aspects of cholesteric liquid crystals. The double-twist configurations we observe exhibit discontinuous layering transitions, domain formation, metastability, and chiral point defects as the concentration of chiral dopant is varied. We demonstrate that these distinct layer states can be distinguished by chiral topological invariants. We show that changes in the layer structure give rise to a chiral soliton similar to a toron, comprising a metastable pair of chiral point defects. Through the applicability of the invariants we describe to general systems, our work has broad relevance to the study of chiral materials.

The potential of Blepharidium guatemalense for nickel agromining in Mexico and Central America.

The aim of this study was to assess the potential of the woody nickel hyperaccumulator species Blepharidium guatemalense (Standl.) Standl. for agromining in southeastern Mexico. Pot trials consisting of nickel dosing (0, 20, 50, 100, and 250 mg Ni kg-1), and synthetic and organic fertilization were conducted. Field trials were also undertaken with different harvesting regimes of B. guatemalense. Foliar nickel concentrations increased significantly with rising nickel additions, with a 300-fold increase at 250 mg Ni kg-1 treatment relative to the control. Synthetic fertilization strongly increased nickel uptake without any change in plant growth or biomass, whereas organic fertilization enhanced plant shoot biomass with a negligible effect on foliar nickel concentrations. A 5-year-old stand which was subsequently harvested twice per year produced the maximum nickel yield tree-1 yr-1, with an estimated total nickel yield of 142 kg ha-1 yr-1. Blepharidium guatemalense is a prime candidate for nickel agromining on account of its high foliar Ni concentrations, high bioconcentration (180) and translocation factors (3.3), fast growth rate and high shoot biomass production. Future studies are needed to test the outcomes of the pot trials in the field. Extensive geochemical studies are needed to identify potential viable agromining locations. Novelty Statement Our research team is a pioneer in the discovery of metal hyperaccumulator plants in Mesoamerica with at least 13 species discovered in the last 2 years. This study is the first to assess the potential of nickel agromining (phytomining) in Mexico (and in all the American continent), using one of the strongest nickel hyperaccumulators reported so far. The promising results of this study are the basis for optimal agricultural management of Blepharidium guatemalense.

Geometry of Bend: Singular Lines and Defects in Twist-Bend Nematics.

We describe the geometry of bend distortions in liquid crystals and their fundamental degeneracies, which we call ß lines; these represent a new class of linelike topological defect in twist-bend nematics. We present constructions for smecticlike textures containing screw and edge dislocations and also for vortexlike structures of double twist and Skyrmions. We analyze their local geometry and global structure, showing that their intersection with any surface is twice the Skyrmion number. Finally, we demonstrate how arbitrary knots and links can be created and describe them in terms of merons, giving a geometric perspective on the fractionalization of Skyrmions.

Impact of a Temporary NRT Enhancement in a State Quitline and Web-Based Program.

PURPOSE: To examine the impact of a nicotine replacement therapy (NRT) enhancement on quit outcomes. DESIGN: Observational study using an intent to treat as treated analysis. SETTING: Not available. PARTICIPANTS: A total of 4022 Idaho tobacco users aged ≥18 years who received services from the Idaho Tobacco Quitline or Idaho's web-based program. INTERVENTION: One-call phone or web-based participants were sent a single 4- or 8-week NRT shipment. Multiple-call participants were sent NRT in a single 4-week shipment or two 4-week shipments (second shipment sent only to those completing a second coaching call). MEASURES: North American Quitline Consortium recommended Minimal Data Set items collected at registration and follow-up. Thirty-day point prevalence quit rates were assessed at 7-month follow-up. ANALYSIS: Multiple logistic regression models were used to examine the effects of program type and amount of NRT sent to participants while controlling for demographic and tobacco use characteristics. RESULTS: Abstinence rates were significantly higher among 8-week versus 4-week NRT recipients (42.5% vs 33.3%). The effect was only significant between multiple-call program participants who received both 4-week NRT shipments versus only the first of 2 possible 4-week shipments (51.1% vs 31.1%). Costs per quit were lowest among web-based participants who received 4 weeks of NRT (US$183 per quit) and highest among multiple-call participants who received only 1 of 2 possible NRT shipments (US$557 per quit). CONCLUSION: To better balance cost with clinical effectiveness, funders of state-based tobacco cessation services may want to consider (1) allowing tobacco users to choose between phone- and web-based programs while (2) limiting longer NRT benefits only to multiple-call program participants.

Effect of combination therapy with bevacizumab and dexamethasone intravitreal implant in patients with retinal vein occlusion.

OBJECTIVE: The objective of this study was to determine if dexamethasone intravitreal implant 0.7 mg (Ozurdex; Allergan, Inc) with bevacizumab (Avastin; Genentech, Inc) therapy can be synergistic, providing further improvements in visual acuity, sustainability, and macular thickness when compared with dexamethasone intravitreal implant 0.7 mg alone. METHODS: This is a prospective, interventional case series intended to monitor changes in visual acuity and macular thickness in patients diagnosed with retinal vein occlusion (RVO), after injection of bevacizumab followed by a scheduled dexamethasone intravitreal implant. This study was designed to emulate patient care as received in the typical ophthalmology practice. Patients diagnosed with RVO, who were seen between September 2009 and July 2010, were included in this study if they had received previous anti-vascular endothelial growth factor therapy. Patients were included in analysis if the previous anti-vascular endothelial growth factor therapy was at least 6 weeks before and optical coherence tomography (OCT) was >300 µm on spectral-domain OCT. Exclusion criteria included history of vitrectomy, and/or rubeotic or advanced glaucoma. All patients were evaluated with Snellen visual acuity and measured for macular thickness (calculated by spectral-domain OCT) and intraocular pressure. At baseline, all patients were injected with bevacizumab, followed by dexamethasone intravitreal implant injection 2 weeks later. These patients were reexamined on a monthly basis and retreated when edema occurred. RESULTS: The primary outcome measure was the time to reinjection based on OCT and vision criteria. The secondary outcomes were increases in visual acuity and the reduction of OCT thickness during that period. Thirty-four eyes of 33 patients, with a mean age of 72.8 years, were identified. Thirty-five percent were diagnosed with central RVO, while the other 65% were with branch RVO. Of these patients, 97% gained vision during the study. Mean visual acuity improved from initially 11 letters to a maximum of 25 letters during the study period. In addition, vision improved by at least 15 letters in 29% of patients initially up to 64% during the study period. Macular thickness decreased with the combination treatment by OCT, and the effect continued an average of 126 days from the initial bevacizumab treatment. Retreatment was unnecessary in 18% of the population during the 6-month study period. CONCLUSION: This study demonstrates efficacy and the duration of effect using a combination of bevacizumab and dexamethasone versus dexamethasone alone. The combination is synergistic, increasing visual acuity and prolonging the time between injections, compared with either of these medications alone. Therefore, the combination of a vascular endothelial growth factor inhibitor and a dexamethasone implant may be a valuable option for RVO treatment.

Improving quality of life in patients with end-stage age-related macular degeneration: focus on miniature ocular implants.

Low vision devices in the past have been mainly extraocular. There are now four new devices in different stages of development and implementation that are currently available. Three of them, the Implantable Miniature Telescope (IMT, VisionCare Ophthalmic Technologies, Saratoga, CA), Intraocular Lens for Visually Impaired People (IOL-VIP, IOL-VIP System, Soleko, Pontecorvo, Italy), and Lipschitz Mirror Implant (LMI, Optolight Vision Technology, Herzlia, Israel) are implanted into the anterior segment while the Argus II (Second Sight Medical Products, Sylmar, CA) is implanted into the posterior segment. The goal of these devices is to increase the patient quality of life which has been measured by Visual Functioning Questionnaire (VFQ) scales. The IMT is the only device that has been shown to increase the VFQ score by seven points at 6 months compared to baseline. It is the only FDA-approved device in the US while the Argus has been approved in Europe. Each of these prosthetics has potential benefits for patients.