Anticoagulation: a practical guide for strabismus surgeons.

An increasing number of surgical strabismus patients are taking oral anticoagulant and antiplatelet agents, with more diverse mechanisms of action than those used in the past. The decision as to whether to continue these drugs throughout the perioperative period is difficult and must be based on the balance between hemorrhagic and thrombotic risk. To help guide strabismus surgeons with clinical management in these cases, we review potential hemorrhagic complications of strabismus surgery and examine the use of anticoagulant and antiplatelet drugs during the perioperative period. Surgical strategies that might help minimize intraoperative hemorrhage in patients on anticoagulant therapy are also discussed

Magnetic form factor of SrFe2_2As2_2

Neutron diffraction measurements have been carried out to investigate the magnetic form factor of the parent SrFe2As2 system of the iron-based superconductors. The general feature is that the form factor is approximately isotropic in wave vector, indicating that multiple d-orbitals of the iron atoms are occupied as expected based on band theory. Inversion of the diffraction data suggests that there is some elongation of the spin density toward the As atoms. We have also extended the diffraction measurements to investigate a possible jump in the c-axis lattice parameter at the structural phase transition, but find no detectable change within the experimental uncertainties

Unsupervised decoding of long-term, naturalistic human neural recordings with automated video and audio annotations

Fully automated decoding of human activities and intentions from direct neural recordings is a tantalizing challenge in brain-computer interfacing. Most ongoing efforts have focused on training decoders on specific, stereotyped tasks in laboratory settings. Implementing brain-computer interfaces (BCIs) in natural settings requires adaptive strategies and scalable algorithms that require minimal supervision. Here we propose an unsupervised approach to decoding neural states from human brain recordings acquired in a naturalistic context. We demonstrate our approach on continuous long-term electrocorticographic (ECoG) data recorded over many days from the brain surface of subjects in a hospital room, with simultaneous audio and video recordings. We first discovered clusters in high-dimensional ECoG recordings and then annotated coherent clusters using speech and movement labels extracted automatically from audio and video recordings. To our knowledge, this represents the first time techniques from computer vision and speech processing have been used for natural ECoG decoding. Our results show that our unsupervised approach can discover distinct behaviors from ECoG data, including moving, speaking and resting. We verify the accuracy of our approach by comparing to manual annotations. Projecting the discovered cluster centers back onto the brain, this technique opens the door to automated functional brain mapping in natural settings

Electron-doping evolution of the low-energy spin excitations in the iron arsenide BaFe2−x_{2-x}Nix_{x}As2_{2} superconductors

We use elastic and inelastic neutron scattering to systematically investigate the evolution of the low-energy spin excitations of the iron arsenide superconductor BaFe2-xNixAs2 as a function of nickel doping x. In the undoped state, BaFe2As2 exhibits a tetragonal-to-orthorhombic structural phase transition and simultaneously develops a collinear antiferromagnetic (AF) order below TN = 143 K. Upon electron-doping of x = 0.075 to induce bulk superconductivity with Tc = 12.3 K, the AF ordering temperature reduces to TN = 58 K.We show that the appearance of bulk superconductivity in BaFe1.925Ni0.075As2 coincides with a dispersive neutron spin resonance in the spin excitation spectra, and a reduction in the static ordered moment. For optimally doped BaFe1.9Ni0.1As2 (Tc = 20 K) and overdoped BaFe1.85Ni0.15As2 (Tc = 15 K) superconductors, the static AF long-range order is completely suppressed and the spin excitation spectra are dominated by a resonance and spin-gap at lower energies. We determine the electron-doping dependence of the neutron spin resonance and spin gap energies, and demonstrate that the three-dimensional nature of the resonance survives into the overdoped regime. If spin excitations are important for superconductivity, these results would suggest that the three-dimensional character of the electronic superconducting gaps are prevalent throughout the phase diagram, and may be critical for superconductivity in these materials

Geometric Phase in Eigenspace Evolution of Invariant and Adiabatic Action Operators

The theory of geometric phase is generalized to a cyclic evolution of the eigenspace of an invariant operator with $N$-fold degeneracy. The corresponding geometric phase is interpreted as a holonomy inherited from the universal connection of a Stiefel U(N)-bundle over a Grassmann manifold. Most significantly, for an arbitrary initial state, this geometric phase captures the inherent geometric feature of the state evolution. Moreover, the geometric phase in the evolution of the eigenspace of an adiabatic action operator is also addressed, which is elaborated by a pullback U(N)-bundle. Several intriguing physical examples are illustrated.Comment: Added Refs. and corrected typos; 4 page

Calculation of dopant solubilities and phase diagrams of X–Pb–Se (X = Br, Na) limited to defects with localized charge

The control of defects, particularly impurities, to tune the concentrations of electrons and holes is of utmost importance in the use of semiconductor materials. To estimate the amount of dopant that can be added to a semiconductor without precipitating secondary phases, a detailed phase diagram is needed. The ability of ab initio computational methods to predict defect stability can greatly accelerate the discovery of new semiconductors by calculating phase diagrams when time-consuming experimental ones are not available. DFT defect energy calculations are particularly successful in identifying doping strategies by determining the energy of multiple defect charge states in large band gap semiconductors and insulators. In metals, detailed phase diagrams can be determined from such calculations but only one, uncharged defect is needed. In this work, we have calculated dopant solubilities of Br and Na in the thermoelectric material PbSe by mapping its solvus boundaries in different regions of the respective ternary phase diagrams using DFT defect energy calculations. The narrow gap PbSe provides an example where defects with nominal charge state (based on valence counting) have properly-localized charge states. However, defects with unexpected charge states produce delocalized electrons, which are then, in effect, defects with the expected charge state. Simply applying the methods for calculating multiple defect charge states in PbSe and treating them as separate defects fails to predict properties measured by experiments. Performing thermodynamic calculations using only the expected charge states, excluding others, enables accurate prediction of experimentally measured doping efficiencies and phase diagrams. Identifying which defect charge states to include in thermodynamic calculations will expedite the use of such calculations for other semiconductors in understanding phase diagrams and devising effective doping strategies

Origin and tuning of the magnetocaloric effect for the magnetic refrigerant MnFe(P1-xGex)

Neutron diffraction and magnetization measurements of the magneto refrigerant Mn1+yFe1-yP1-xGex reveal that the ferromagnetic and paramagnetic phases correspond to two very distinct crystal structures, with the magnetic entropy change as a function of magnetic field or temperature being directly controlled by the phase fraction of this first-order transition. By tuning the physical properties of this system we have achieved a maximum magnetic entropy change exceeding 74 J/Kg K for both increasing and decreasing field, more than twice the value of the previous record.Comment: 6 Figures. One tabl

Image-guided high-dose-rate brachytherapy: preliminary outcomes and toxicity of a joint interventional radiology and radiation oncology technique for achieving local control in challenging cases.

PurposeTo determine the ability of image-guided high-dose-rate brachytherapy (IG-HDR) to provide local control (LC) of lesions in non-traditional locations for patients with heavily pre-treated malignancies.Material and methodsThis retrospective series included 18 patients treated between 2012 and 2014 with IG-HDR, either in combination with external beam radiotherapy (EBRT; n = 9) or as monotherapy (n = 9). Lesions were located in the pelvis (n = 5), extremity (n = 2), abdomen/retroperitoneum (n = 9), and head/neck (n = 2). All cases were performed in conjunction between interventional radiology and radiation oncology. Toxicity was graded based on CTCAE v4.0 and local failure was determined by RECIST criteria. Kaplan-Meier analysis was performed for LC and overall survival.ResultsThe median follow-up was 11.9 months. Two patients had localized disease at presentation; the remainder had recurrent and/or metastatic disease. Seven patients had prior EBRT, with a median equivalent dose in 2 Gy fractions (EQD2) of 47.0 Gy. The median total EQD2s were 34 Gy and 60.9 Gy for patients treated with monotherapy or combination therapy, respectively. Image-guided high-dose rate brachytherapy was delivered in one to six fractions. Six patients had local failures at a median interval of 5.27 months with a one-year LC rate of 59.3% and a one-year overall survival of 40.7%. Six patients died from their disease at a median interval of 6.85 months from the end of treatment. There were no grade ≥ 3 acute toxicities but two patients had serious long term toxicities.ConclusionsWe demonstrate a good one year LC rate of nearly 60%, and a favorable toxicity profile when utilizing IG-HDR to deliver high doses of radiation with high precision into targets not readily accessible by other forms of local therapy. These preliminary results suggest that further studies utilizing this approach may be considered for patients with difficult to access lesions that require LC

Psychometric properties of standardized balance confidence, fear of falling, and falls-efficacy measures in people with lower limb amputations

Background: In Canada, \u3e50% of community-dwelling lower limb amputees (LLA) fall at least once each year, a rate that is almost twice that of community-dwelling older adults. While the physical consequences of falls may be readily apparent, psychological sequelae that follow may be just as, if not more, detrimental than an actual fall itself. Current measures of balance confidence show no change in LLA following discharge from rehabilitation. The limited detectable change may be due to content validity challenges of the measures as they were not developed for the unique challenges faced by LLA. Objectives: 1) Review items from standardized scales measuring falls-related concerns with participants to determine the applicability of test items to the LLA population. 2) Solicit novel examples of relevant activities from participants to inform the development of an LLA-specific balance confidence scale. Proposed Methods: This cross-sectional study will include adult unilateral/bilateral LLA (n=60) recruited through the Outpatient Amputee Rehabilitation Program at Parkwood Institute. Falls-related concerns will be evaluated using seven relevant clinical measures of a concern for falling. Participants will be asked to identify inapplicable questions and to provide i) a list of activities they are physically able to do but are avoiding; and ii) a list of activities they currently do but are worried about becoming unsteady or falling when performed. Future Directions/Implications: The results of this project could provide important details for the creation of an amputee-specific measurement tool to better quantify psychological concerns related to falls