Coherent scattering of near-resonant light by a dense microscopic cold atomic cloud

We measure the coherent scattering of light by a cloud of laser-cooled atoms with a size comparable to the wavelength of light. By interfering a laser beam tuned near an atomic resonance with the field scattered by the atoms, we observe a resonance with a redshift, a broadening, and a saturation of the extinction for increasing atom numbers. We attribute these features to enhanced light-induced dipole-dipole interactions in a cold, dense atomic ensemble that result in a failure of standard predictions such as the “cooperative Lamb shift”. The description of the atomic cloud by a mean-field model based on the Lorentz-Lorenz formula that ignores scattering events where light is scattered recurrently by the same atom and by a microscopic discrete dipole model that incorporates these effects lead to progressively closer agreement with the observations, despite remaining difference

Citrate confers less filter-induced complement activation and neutrophil degranulation than heparin when used for anticoagulation during continuous venovenous haemofiltration in critically ill patients

Background: During continuous venovenous haemofiltration (CVVH), regional anticoagulation with citrate may be superior to heparin in terms of biocompatibility, since heparin as opposed to citrate may activate complement (reflected by circulating C5a) and induce neutrophil degranulation in the filter and myeloperoxidase (MPO) release from endothelium. Methods. No anticoagulation (n = 13), unfractionated heparin (n = 8) and trisodium citrate (n = 17) regimens during CVVH were compared. Blood samples were collected pre- and postfilter; C5a, elastase and MPO were determined by ELISA. Additionally, C5a was also measured in the ultrafiltrate. Results: In the heparin group, there was C5a production across the filter which most decreased over time as compared to other groups (P = 0.007). There was also net production of elastase and MPO across the filter during heparin anticoagulation (P = 0.049 or lower), while production was minimal and absent in the no anticoagulation and citrate group, respectively. During heparin anticoagulation, plasma concentrations of MPO at the inlet increased in the first 10 minutes of CVVH (P = 0.024). Conclusion: Citrate confers less filter-induced, potentially harmful complement activation and neutrophil degranulation and less endothelial activation than heparin when used for anticoagulation during continuous venovenous haemofiltration in critically ill patients

Super-Resolution without Imaging: Library-Based Approaches Using Near-to-Far-Field Transduction by a Nanophotonic Structure

Super-resolution imaging is often viewed in terms of engineering narrow point spread functions, but nanoscale optical metrology can be performed without real-space imaging altogether. In this paper, we investigate how partial knowledge of scattering nanostructures enables extraction of nanoscale spatial information from far-field radiation patterns. We use principal component analysis to find patterns in calibration data and use these patterns to retrieve the position of a point source of light. In an experimental realization using angle-resolved cathodoluminescence, we retrieve the light source position with an average error below λ/100. The patterns found by principal component analysis reflect the underlying scattering physics and reveal the role the scattering nanostructure plays in localization success. The technique described here is highly general and can be applied to gain insight into and perform subdiffractive parameter retrieval in various applications

Coagulation, Fibrinolysis and Inhibitors in Failing Filters during Continuous Venovenous Hemofiltration in Critically Ill Patients with Acute Kidney Injury: Effect of Anticoagulation Modalities

Introduction: The mechanisms of early filter failure and clotting with different anticoagulation modalities during continuous venovenous hemofiltration (CVVH) are largely unknown. Methods: Citrate, heparin and no anticoagulation were compared. Blood was drawn pre- and post filter up to 720 min. Concentrations of the thrombin-antithrombin (TAT), activated protein C-protein C inhibitor (APC-PCI), and type I plasminogen activator inhibitor (PAI-1) were determined. Results: In case of early filter failure (<24 h), inlet concentrations of TAT and APC-PCI were higher over time, irrespective of anticoagulation. There was more production of APC-PCI and platelet-derived PAI-1 in the filter after 10 min in the heparin group than in other groups. In clotting filters, production of APC-PCI and PAI was also higher with heparin than citrate. Conclusion: Coagulation activation in plasma and inhibition of anticoagulation in plasma and filter may partly determine early CVVH filter failure due to clotting, particularly when heparin is used. Regional anticoagulation by citrate circumvents the inhibition of anticoagulation and fibrinolysis by platelet activation following heparin. (C) 2015 S. Karger AG, Base

Stability Design of the Filter with Head Loss

The optimum design of the filter with head loss is performed using S_ as a parameter of stability, where S_ is an area of distribution of the residual vertical effective normal stress σ_. in a critical state. The following three types of distributions of coefficient of permeability k are investigated precisely here : (1) Two-layer varying type, (2) locally linearly varying type, (3) locally bi-hyperbolically varying type and (4) locally hyperbolically varying type, which are considered to be able to represent almost all distributions of k of a filter. The filter is approximated to a 1000-layered system systematically and S_ of the filter is analysed using the computer program CRIT1 (Critical State Calculation Program for Seepage Failure of a Multi-Layered Ground). In this paper, the various cases of k_r (>1.0) are investigated systematically, where k_r is the ratio of coefficients of permeability at the top and the bottom of a filter. The following results are then obtained : (1) For a given value of k_r, the two-layered system : [numerical formula] is the most stable against seepage failure, where [numerical formula] is the ratio of lengths of the upper and the lower strata of the two-layered system. The superscript * represents the value of the most stable filter. (2) l_r^* increases from 1.0+0 to infinity (l_1^* decreases from 1/2L-0 to 0.0+0), as k_r increases from 1.0+0 to infinity, where L is the total length of the most stable filter. That is to say, the two layer varying point of the most stable filter is descending from the middle to the bottom of the filter, as k_r increases from 1.0+0 to infinity. (3) [numerical formula] is increasing from 0.0+0 to 1.0-0,as k_r increases from 1.0+0 to infinity, where S_ is the value of S_ of the most stable filter. S_ is represented as : [numerical formula] (4) k_^* is increasing from 1.0+0 to infinity, as k_r increases from 1.0+0 to infinity, where k_^* is the average coefficient of permeability of the most stable filter and k_l is the coefficient of permeability at the bottom of the filter. k_^* is represented as : [numerical formula]