Minimising the number of gap-zeros in binary matrices

We study a problem of minimising the total number of zeros in the gaps between blocks of consecutive ones in the columns of a binary matrix by permuting its rows. The problem is referred to as the Consecutive Ones Matrix Augmentation Problem, and is known to be NP-hard. An analysis of the structure of an optimal solution allows us to focus on a restricted solution space, and to use an implicit representation for searching the space. We develop an exact solution algorithm, which is linear-time in the number of rows if the number of columns is constant, and two constructive heuristics to tackle instances with an arbitrary number of columns. The heuristics use a novel solution representation based upon row sequencing. In our computational study, all heuristic solutions are either optimal or close to an optimum. One of the heuristics is particularly effective, especially for problems with a large number of rows

Correction: Carbon dioxide uptake from natural gas by binary ionic liquid–water mixtures

Correction for ‘Carbon dioxide uptake from natural gas by binary ionic liquid–water mixtures’ by Kris Anderson et al., Green Chem., 2015, DOI: 10.1039/c5gc00720h

Carbon dioxide uptake from natural gas by binary ionic liquid water mixtures

[EN] Carbon dioxide solubility in a set of carboxylate ionic liquids formulated with stoicheiometric amounts of water is found to be significantly higher than for other ionic liquids previously reported. This is due to synergistic chemical and physical absorption. The formulated ionic liquid/water mixtures show greatly enhanced carbon dioxide solubility relative to both anhydrous ionic liquids and aqueous ionic liquid solutions, and are competitive with commercial chemical absorbers, such as activated N-methyldiethanolamine or monoethanolamine.The authors would like to acknowledge PETRONAS for financial support of this research, and Cytec (especially Dr Al Robertson) for supplying some of the phosphonium ionic liquids used.Anderson, K.; Atkins, MP.; Estager, J.; Kuah, Y.; Ng, S.; Oliferenko, AA.; Plechkova, NV.... (2015). Carbon dioxide uptake from natural gas by binary ionic liquid water mixtures. Green Chemistry. 17(8):4340-4354. https://doi.org/10.1039/c5gc00720hS43404354178Cenovus, http://www.cenovus.com/operations/technology/co2-enhanced-oil-recovery.htmlV. Alvarado and E.Manrique, Enhanced Oil Recovery: Field Planning and Development Strategies, Gulf Professional Publishing, Amsterdam, 2010British Petroleum , In Salah Gas, http://www.insalahco2.com/index.php?option=com_content&view=frontpage&Itemid=1&lang=enN. Stern , The Economics of Climate Change: The Stern Review, Cambridge University Press, Cambridge, 2007Alvarado, V., & Manrique, E. (2010). Enhanced Oil Recovery: An Update Review. Energies, 3(9), 1529-1575. doi:10.3390/en3091529S. Rackley , Carbon Capture and Storage, Elsevier Science, Oxford, 2009H. Huppert , Carbon Capture and Storage in Europe EASAC Policy Report 20, German National Academy of Sciences, Leopoldina, 2013Organisation for the Prohibition of Chemical Weapons (OPCW) , The Chemical Weapons Convention, http://www.opcw.org/html/db/cwc/eng/cwc_frameset.htmlRubin, E. S., Mantripragada, H., Marks, A., Versteeg, P., & Kitchin, J. (2012). The outlook for improved carbon capture technology. Progress in Energy and Combustion Science, 38(5), 630-671. doi:10.1016/j.pecs.2012.03.003G. H. Koch , M. P. H.Brongers, N. G.Thompson, Y. P.Virmani and J. H.Payer, Corrosion Costs and Preventive Strategies in the United States FHWA-RD-01-156, CC Technologies Laboratories, Inc, NACE International, 2001Law Offices of Casper Meadows Schwartz & Cook, ‘$80 Million Recovery in Toxic Exposure Suit’, http://www.cmslaw.com/Verdicts-Settlements/80-Million-Recovery-in-Toxic-Exposure-Suit.shtmlL. Grunwald , U.S. EPA Cites UNOCAL for Spill Violations, Press Release, United States Environmental Protection Agency, 1995Lee, K. B., Beaver, M. G., Caram, H. S., & Sircar, S. (2008). Reversible Chemisorbents for Carbon Dioxide and Their Potential Applications. Industrial & Engineering Chemistry Research, 47(21), 8048-8062. doi:10.1021/ie800795yDu, N., Park, H. B., Dal-Cin, M. M., & Guiver, M. D. (2012). Advances in high permeability polymeric membrane materials for CO2separations. Energy Environ. Sci., 5(6), 7306-7322. doi:10.1039/c1ee02668bM. Freemantle , An Introduction to Ionic Liquids, RSC Publications, Cambridge, UK, 2010Earle, M. J., Esperança, J. M. S. S., Gilea, M. A., Canongia Lopes, J. N., Rebelo, L. P. N., Magee, J. W., … Widegren, J. A. (2006). The distillation and volatility of ionic liquids. Nature, 439(7078), 831-834. doi:10.1038/nature04451Forsyth, M., Howlett, P. C., Tan, S. K., MacFarlane, D. R., & Birbilis, N. (2006). An Ionic Liquid Surface Treatment for Corrosion Protection of Magnesium Alloy AZ31. Electrochemical and Solid-State Letters, 9(11), B52. doi:10.1149/1.2344826Fraser, K. J., & MacFarlane, D. R. (2009). Phosphonium-Based Ionic Liquids: An Overview. Australian Journal of Chemistry, 62(4), 309. doi:10.1071/ch08558K. R. Seddon , Ionic liquids: Designer solvents?, in The International George Papatheodorou Symposium: Proceedings, ed. S. Boghosian, V. Dracopoulos, C. G. Kontoyannis and G. A. Voyiatzis, Institute of Chemical Engineering and High Temperature Chemical Processes, Patras, 1999, pp. 131–135M. Deetlefs , M.Fanselow and K. R.Seddon, RSC Adv.W. Freyland , Coulombic Fluids: Bulk and Interfaces, Springer, Heidelberg, 2011Electrodeposition from Ionic Liquids, ed. F. Endres, D. MacFarlane and A. Abbott, Wiley-VCH, Weinheim, 2008Electrochemical Aspects of Ionic Liquids, ed. H. Ohno, Wiley-Interscience, Hoboken, New Jersey, 2005Ionic Liquids: From Knowledge to Application, ed. N. V. Plechkova, R. D. Rogers and K. R. Seddon, American Chemical Society, Washington D.C., 2009Ionic Liquids in Synthesis, ed. P. Wasserscheid and T. Welton, Wiley-VCH, Weinheim, 2nd edn, 2008Plechkova, N. V., & Seddon, K. R. (2008). Applications of ionic liquids in the chemical industry. Chem. Soc. Rev., 37(1), 123-150. doi:10.1039/b006677jIonic Liquids UnCOILed: Critical Expert Overviews, ed. N. V. Plechkova and K. R. Seddon, Wiley, Hoboken, New Jersey, 2013Ionic Liquids Further UnCOILed: Critical Expert Overviews, ed. N. V. Plechkova and K. R. Seddon, Wiley, Hoboken, New Jersey, 2014Ionic Liquids Completely UnCOILed: Critical Expert Overviews, ed. N. V. Plechkova and K. R. Seddon, Wiley, Hoboken, New Jersey, 2015Blanchard, L. A., Hancu, D., Beckman, E. J., & Brennecke, J. F. (1999). Green processing using ionic liquids and CO2. Nature, 399(6731), 28-29. doi:10.1038/19887C. Villagrán , C. E.Banks, M.Deetlefs, G.Driver, W. R.Pitner, R. G.Compton and C.Hardacre, Chloride Determination in Ionic Liquids, in Ionic Liquids IIIB: Fundamentals, Progress, Challenges, and Opportunities - Transformations and Processes, ed. R. D. Rogers and K. R. Seddon, ACS Symp. Ser., Vol. 902, American Chemical Society, Washington D.C., 2005, vol. 902, pp. 244–258J. L. Anthony , E. J.Maginn and J. F.Brennecke, Gas Solubilities in 1-n-Butyl-3-methylimidazolium Hexafluorophosphate, in Ionic Liquids: Industrial Applications to Green Chemistry, ed. R. D. Rogers and K. R. Seddon, ACS Symp. Ser, Vol. 818, American Chemical Society, Washington D.C., 2002, vol. 818, pp. 260–269J. H. Davis Jr. , Working Salts: Syntheses and Uses of Ionic Liquids Containing Functionalized Ions, in Ionic Liquids: Industrial Applications to Green Chemistry, ed. R. D. Rogers and K. R. Seddon, ACS Symp. Ser, Vol. 818, American Chemical Society, Washington D.C., 2002, vol. 818, pp. 247–259Bates, E. D., Mayton, R. D., Ntai, I., & Davis, J. H. (2002). CO2Capture by a Task-Specific Ionic Liquid. Journal of the American Chemical Society, 124(6), 926-927. doi:10.1021/ja017593dWang, C., Luo, X., Zhu, X., Cui, G., Jiang, D., Deng, D., … Dai, S. (2013). The strategies for improving carbon dioxide chemisorption by functionalized ionic liquids. RSC Advances, 3(36), 15518. doi:10.1039/c3ra42366bRamdin, M., de Loos, T. W., & Vlugt, T. J. H. (2012). State-of-the-Art of CO2Capture with Ionic Liquids. Industrial & Engineering Chemistry Research, 51(24), 8149-8177. doi:10.1021/ie3003705Zhang, X., Zhang, X., Dong, H., Zhao, Z., Zhang, S., & Huang, Y. (2012). Carbon capture with ionic liquids: overview and progress. Energy & Environmental Science, 5(5), 6668. doi:10.1039/c2ee21152aYokozeki, A., & Shiflett, M. B. (2009). Separation of Carbon Dioxide and Sulfur Dioxide Gases Using Room-Temperature Ionic Liquid [hmim][Tf2N]. Energy & Fuels, 23(9), 4701-4708. doi:10.1021/ef900649cCabaço, M. I., Besnard, M., Danten, Y., & Coutinho, J. A. P. (2012). Carbon Dioxide in 1-Butyl-3-methylimidazolium Acetate. I. Unusual Solubility Investigated by Raman Spectroscopy and DFT Calculations. The Journal of Physical Chemistry A, 116(6), 1605-1620. doi:10.1021/jp211211nCarvalho, P. J., Álvarez, V. H., Schröder, B., Gil, A. M., Marrucho, I. M., Aznar, M., … Coutinho, J. A. P. (2009). Specific Solvation Interactions of CO2on Acetate and Trifluoroacetate Imidazolium Based Ionic Liquids at High Pressures. The Journal of Physical Chemistry B, 113(19), 6803-6812. doi:10.1021/jp901275bGoodrich, B. F., de la Fuente, J. C., Gurkan, B. E., Zadigian, D. J., Price, E. A., Huang, Y., & Brennecke, J. F. (2011). Experimental Measurements of Amine-Functionalized Anion-Tethered Ionic Liquids with Carbon Dioxide. Industrial & Engineering Chemistry Research, 50(1), 111-118. doi:10.1021/ie101688aGoodrich, B. F., de la Fuente, J. C., Gurkan, B. E., Lopez, Z. K., Price, E. A., Huang, Y., & Brennecke, J. F. (2011). Effect of Water and Temperature on Absorption of CO2by Amine-Functionalized Anion-Tethered Ionic Liquids. The Journal of Physical Chemistry B, 115(29), 9140-9150. doi:10.1021/jp2015534Ferguson, J. L., Holbrey, J. D., Ng, S., Plechkova, N. V., Seddon, K. R., Tomaszowska, A. A., & Wassell, D. F. (2011). A greener, halide-free approach to ionic liquid synthesis. Pure and Applied Chemistry, 84(3), 723-744. doi:10.1351/pac-con-11-07-21Shiflett, M. B., Kasprzak, D. J., Junk, C. P., & Yokozeki, A. (2008). Phase behavior of {carbon dioxide+[bmim][Ac]} mixtures. The Journal of Chemical Thermodynamics, 40(1), 25-31. doi:10.1016/j.jct.2007.06.003Shiflett, M. B., & Yokozeki, A. (2009). Phase Behavior of Carbon Dioxide in Ionic Liquids: [emim][Acetate], [emim][Trifluoroacetate], and [emim][Acetate] + [emim][Trifluoroacetate] Mixtures. Journal of Chemical & Engineering Data, 54(1), 108-114. doi:10.1021/je800701jShiflett, M. B., Drew, D. W., Cantini, R. A., & Yokozeki, A. (2010). Carbon Dioxide Capture Using Ionic Liquid 1-Butyl-3-methylimidazolium Acetate. Energy & Fuels, 24(10), 5781-5789. doi:10.1021/ef100868aCabaço, M. I., Besnard, M., Danten, Y., & Coutinho, J. A. P. (2011). Solubility of CO2in 1-Butyl-3-methyl-imidazolium-trifluoro Acetate Ionic Liquid Studied by Raman Spectroscopy and DFT Investigations. The Journal of Physical Chemistry B, 115(13), 3538-3550. doi:10.1021/jp111453aGurau, G., Rodríguez, H., Kelley, S. P., Janiczek, P., Kalb, R. S., & Rogers, R. D. (2011). Demonstration of Chemisorption of Carbon Dioxide in 1,3-Dialkylimidazolium Acetate Ionic Liquids. Angewandte Chemie International Edition, 50(50), 12024-12026. doi:10.1002/anie.201105198Besnard, M., Cabaço, M. I., Vaca Chávez, F., Pinaud, N., Sebastião, P. J., Coutinho, J. A. P., … Danten, Y. (2012). CO2 in 1-Butyl-3-methylimidazolium Acetate. 2. NMR Investigation of Chemical Reactions. The Journal of Physical Chemistry A, 116(20), 4890-4901. doi:10.1021/jp211689zJaniczek, P., Kalb, R. S., Thonhauser, G., & Gamse, T. (2012). Carbon dioxide absorption in a technical-scale-plant utilizing an imidazolium based ionic liquid. Separation and Purification Technology, 97, 20-25. doi:10.1016/j.seppur.2012.03.003Ober, C. A., & Gupta, R. B. (2012). pH Control of Ionic Liquids with Carbon Dioxide and Water: 1-Ethyl-3-methylimidazolium Acetate. Industrial & Engineering Chemistry Research, 51(6), 2524-2530. doi:10.1021/ie201529dStevanovic, S., Podgoršek, A., Pádua, A. A. H., & Costa Gomes, M. F. (2012). Effect of Water on the Carbon Dioxide Absorption by 1-Alkyl-3-methylimidazolium Acetate Ionic Liquids. The Journal of Physical Chemistry B, 116(49), 14416-14425. doi:10.1021/jp3100377Stevanovic, S., Podgorsek, A., Moura, L., Santini, C. C., Padua, A. A. H., & Costa Gomes, M. F. (2013). Absorption of carbon dioxide by ionic liquids with carboxylate anions. International Journal of Greenhouse Gas Control, 17, 78-88. doi:10.1016/j.ijggc.2013.04.017Wang, G., Hou, W., Xiao, F., Geng, J., Wu, Y., & Zhang, Z. (2011). Low-Viscosity Triethylbutylammonium Acetate as a Task-Specific Ionic Liquid for Reversible CO2Absorption. Journal of Chemical & Engineering Data, 56(4), 1125-1133. doi:10.1021/je101014qWilhelm, E., Battino, R., & Wilcock, R. J. (1977). Low-pressure solubility of gases in liquid water. Chemical Reviews, 77(2), 219-262. doi:10.1021/cr60306a003Miyano, Y., & Fujihara, I. (2004). Henry’s constants of carbon dioxide in methanol at 250–500 K. Fluid Phase Equilibria, 221(1-2), 57-62. doi:10.1016/j.fluid.2004.04.017Fernandez, E. S., & Goetheer, E. L. V. (2011). DECAB: Process development of a phase change absorption process. Energy Procedia, 4, 868-875. doi:10.1016/j.egypro.2011.01.131Zhang, J., Zhang, S., Dong, K., Zhang, Y., Shen, Y., & Lv, X. (2006). Supported Absorption of CO2 by Tetrabutylphosphonium Amino Acid Ionic Liquids. Chemistry - A European Journal, 12(15), 4021-4026. doi:10.1002/chem.200501015Saravanamurugan, S., Kunov-Kruse, A. J., Fehrmann, R., & Riisager, A. (2014). Amine-Functionalized Amino Acid-based Ionic Liquids as Efficient and High-Capacity Absorbents for CO2. ChemSusChem, 7(3), 897-902. doi:10.1002/cssc.201300691J. Speight , Lange's Handbook of Chemistry, McGraw-Hill, New York, 16th edn, 2005, Section 1.18, pp. 1.310–1.314Cammarata, L., Kazarian, S. G., Salter, P. A., & Welton, T. (2001). Molecular states of water in room temperature ionic liquidsElectronic Supplementary Information available. See http://www.rsc.org/suppdata/cp/b1/b106900d/. Physical Chemistry Chemical Physics, 3(23), 5192-5200. doi:10.1039/b106900dNitta, I., Tomiie, Y., & Koo, C. H. (1952). The crystal structure of potassium bicarbonate, KHCO3. Acta Crystallographica, 5(2), 292-292. doi:10.1107/s0365110x52000848Sass, R. L., & Scheuerman, R. F. (1962). The crystal structure of sodium bicarbonate. Acta Crystallographica, 15(1), 77-81. doi:10.1107/s0365110x62000158Adamová, G., Gardas, R. L., Nieuwenhuyzen, M., Puga, A. V., Rebelo, L. P. N., Robertson, A. J., & Seddon, K. R. (2012). Alkyltributylphosphonium chloride ionic liquids: synthesis, physicochemical properties and crystal structure. Dalton Transactions, 41(27), 8316. doi:10.1039/c1dt10466gGottlieb, H. E., Kotlyar, V., & Nudelman, A. (1997). NMR Chemical Shifts of Common Laboratory Solvents as Trace Impurities. The Journal of Organic Chemistry, 62(21), 7512-7515. doi:10.1021/jo971176vSheldrick, G. M. (2007). A short history ofSHELX. Acta Crystallographica Section A Foundations of Crystallography, 64(1), 112-122. doi:10.1107/s0108767307043930Allen, F. H., & Motherwell, W. D. S. (2002). Applications of the Cambridge Structural Database in organic chemistry and crystal chemistry. Acta Crystallographica Section B Structural Science, 58(3), 407-422. doi:10.1107/s0108768102004895Ramnial, T., Taylor, S. A., Bender, M. L., Gorodetsky, B., Lee, P. T. K., Dickie, D. A., … Clyburne, J. A. C. (2008). Carbon-Centered Strong Bases in Phosphonium Ionic Liquids. The Journal of Organic Chemistry, 73(3), 801-812. doi:10.1021/jo701289dDietzel, P. D. C., & Jansen, M. (2002). Tetramethylphosphonium hydrogen carbonate. Acta Crystallographica Section E Structure Reports Online, 58(9), o1003-o1004. doi:10.1107/s1600536802013168Li, H., Hou, Y., & Yang, Y. (2011). Tetraethylammonium bicarbonate trihydrate. Acta Crystallographica Section E Structure Reports Online, 67(8), o1991-o1991. doi:10.1107/s1600536811026080McMullan, R., & Jeffrey, G. A. (1959). Hydrates of the Tetran‐butyl and Tetrai‐amyl Quaternary Ammonium Salts. The Journal of Chemical Physics, 31(5), 1231-1234. doi:10.1063/1.1730574Smiglak, M., Hines, C. C., & Rogers, R. D. (2010). New hydrogen carbonate precursors for efficient and byproduct-free syntheses of ionic liquids based on 1,2,3-trimethylimidazolium and N,N-dimethylpyrrolidinium cores. Green Chemistry, 12(3), 491. doi:10.1039/b920003gMaton, C., Van Hecke, K., & Stevens, C. V. (2015). Peralkylated imidazolium carbonate ionic liquids: synthesis using dimethyl carbonate, reactivity and structure. New Journal of Chemistry, 39(1), 461-468. doi:10.1039/c4nj01301hBondi, A. (1964). van der Waals Volumes and Radii. The Journal of Physical Chemistry, 68(3), 441-451. doi:10.1021/j100785a001Van den Berg, J.-A., & Seddon, K. R. (2003). Critical Evaluation of C−H···X Hydrogen Bonding in the Crystalline State. Crystal Growth & Design, 3(5), 643-661. doi:10.1021/cg034083hAdamová, G., Canongia Lopes, J. N., Rebelo, L. P. N., Santos, L. M. N. B., Seddon, K. R., & Shimizu, K. (2014). The alternation effect in ionic liquid homologous series. Phys. Chem. Chem. Phys., 16(9), 4033-4038. doi:10.1039/c3cp54584aAdamová, G., Gardas, R. L., Nieuwenhuyzen, M., Puga, A. V., Rebelo, L. P. N., Robertson, A. J., & Seddon, K. R. (2012). Alkyltributylphosphonium chloride ionic liquids: synthesis, physicochemical properties and crystal structure. Dalton Transactions, 41(27), 8316. doi:10.1039/c1dt10466gM. B. Shiflett and A.Yokozeki, Phase Behaviour of Gases in Ionic Liquids, in Ionic Liquids UnCOILed: Critical Expert Overviews, ed. N. V. Plechkova and K. R. Seddon, Wiley, Hoboken, New Jersey, 2013, pp. 349–398Ibrahim, A. Y., Ashour, F. H., Ghallab, A. O., & Ali, M. (2014). Effects of piperazine on carbon dioxide removal from natural gas using aqueous methyl diethanol amine. Journal of Natural Gas Science and Engineering, 21, 894-899. doi:10.1016/j.jngse.2014.10.011Anonymous , Piperazine – Why It's Used And How It Works, The Contractor (Optimized Gas Treating, Inc.), Houston, 2008, 2 [4], http://www.ogtrt.com/files/contactors/vol_2_issue_4.pd

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Polarization squeezing and continuous-variable polarization entanglement

The Stokes-parameter operators and the associated Poincare sphere, which describe the quantum-optical polarization properties of light, are defined and their basic properties are reviewed. The general features of the Stokes operators are illustrated by evaluation of their means and variances for a range of simple polarization states. Some of the examples show polarization squeezing, in which the variances of one or more Stokes parameters are smaller than the coherent-state value. The main object of the paper is the application of these concepts to bright squeezed light. It is shown that a light beam formed by interference of two orthogonally-polarized quadrature-squeezed beams exhibits squeezing in some of the Stokes parameters. Passage of such a primary polarization-squeezed beam through suitable optical components generates a pair of polarization-entangled light beams with the nature of a two-mode squeezed state. The use of pairs of primary polarization-squeezed light beams leads to substantially increased entanglement and to the generation of EPR-entangled light beams. The important advantage of these nonclassical polarization states for quantum communication is the possibility of experimentally determining all of the relevant conjugate variables of both squeezed and entangled fields using only linear optical elements followed by direct detection.Comment: 27 pages, including 10 figure

Data Descriptor: Australia’s continental-scale acoustic tracking database and its automated quality control process

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ The Creative Commons Public Domain Dedication waiver http://creativecommons.org/publicdomain/zero/1.0/ applies to the metadata files made available in this article.Our ability to predict species responses to environmental changes relies on accurate records of animal movement patterns. Continental-scale acoustic telemetry networks are increasingly being established worldwide, producing large volumes of information-rich geospatial data. During the last decade, the Integrated Marine Observing System’s Animal Tracking Facility (IMOS ATF) established a permanent array of acoustic receivers around Australia. Simultaneously, IMOS developed a centralised national database to foster collaborative research across the user community and quantify individual behaviour across a broad range of taxa. Here we present the database and quality control procedures developed to collate 49.6 million valid detections from 1891 receiving stations. This dataset consists of detections for 3,777 tags deployed on 117 marine species, with distances travelled ranging from a few to thousands of kilometres. Connectivity between regions was only made possible by the joint contribution of IMOS infrastructure and researcher-funded receivers. This dataset constitutes a valuable resource facilitating meta-analysis of animal movement, distributions, and habitat use, and is important for relating species distribution shifts with environmental covariates

A database of marine phytoplankton abundance, biomass and species composition in Australian waters

There have been many individual phytoplankton datasets collected across Australia since the mid 1900s, but most are unavailable to the research community. We have searched archives, contacted researchers, and scanned the primary and grey literature to collate 3,621,847 records of marine phytoplankton species from Australian waters from 1844 to the present. Many of these are small datasets collected for local questions, but combined they provide over 170 years of data on phytoplankton communities in Australian waters. Units and taxonomy have been standardised, obviously erroneous data removed, and all metadata included. We have lodged this dataset with the Australian Ocean Data Network (http://portal.aodn.org.au/) allowing public access. The Australian Phytoplankton Database will be invaluable for global change studies, as it allows analysis of ecological indicators of climate change and eutrophication (e.g., changes in distribution; diatom:dinoflagellate ratios). In addition, the standardised conversion of abundance records to biomass provides modellers with quantifiable data to initialise and validate ecosystem models of lower marine trophic levels

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder