Online brand communities: when consumers are negatively engaged

The goal of the current research is to explore the influence of negative engagement on committing participants in hate online brand communities. To reach this aim, three brands are used to assess this phenomenon (Starbucks, Apple, and McDonald’s), and three related hate online brand communities of such brands are involved. An online questionnaire is developed based on previously validated scales and fulfilled by 300 online members of mentioned communities. Findings reveal the importance of Brand influence, Helping, and Self-expression dimensions on participants to be committed to hating brand communities.info:eu-repo/semantics/acceptedVersio

The advancement of blood cell research by optical tweezers

Demonstration of the light radiation pressure on a microscopic level by A. Ashkin led to the invention of optical tweezers (OT). Applied in the studies of living systems, OT have become a preferable instrument for the noninvasive study of microobjects, allowing manipulation and measurement of the mechanical properties of molecules, organelles, and cells. In the present paper, we overview OT applications in hemorheological research, placing emphasis on red blood cells but also discussing OT applications for the investigation of the biomechanics of leukocytes and platelets. Blood properties have always served as a primary parameter in medical diagnostics due to the interconnection with the physiological state of an organism. Despite blood testing being a well-established procedure of conventional medicine, there are still many complex processes that must be unraveled to improve our understanding and contribute to future medicine. OT are advancing single-cell research, promising new insights into individual cell characteristics compared to the traditional approaches. We review the fundamental and practical findings revealed in blood research through the optical manipulation, stretching, guiding, immobilization, and inter-/intracellular force measurements of single blood cells

Lateral forces on circularly polarizable particles near a surface

Optical forces allow manipulation of small particles and control of nanophotonic structures with light beams. While some techniques rely on structured light to move particles using field intensity gradients, acting locally, other optical forces can push particles on a wide area of illumination but only in the direction of light propagation. Here we show that spin orbit coupling, when the spin of the incident circularly polarized light is converted into lateral electromagnetic momentum, leads to a lateral optical force acting on particles placed above a substrate, associated with a recoil mechanical force. This counterintuitive force acts in a direction in which the illumination has neither a field gradient nor propagation. The force direction is switchable with the polarization of uniform, plane wave illumination, and its magnitude is comparable to other optical forces.This work has been supported, in part, by EPSRC (UK). A.V.Z. acknowledges support from the Royal Society and the Wolfson Foundation. N.E. acknowledges partial support from the US Office of Naval Research Multidisciplinary University Research Initiative Grant No. N00014-10-1-0942. A.M. acknowledges support from the Spanish Government (contract Nos TEC2011-28664-C02-02 and TEC2014-51902-C2-1-R).Rodríguez Fortuño, FJ.; Engheta, N.; Martínez Abietar, AJ.; Zayats, AV. (2015). Lateral forces on circularly polarizable particles near a surface. Nature Communications. 6(8799):1-7. https://doi.org/10.1038/ncomms9799S1768799Novotny, L. & Hecht, B. Principles of Nano-Optics Cambridge University Press (2011).Jackson, J. D. Classical Electrodynamics Wiley (1998).Ashkin, A. & Dziedzic, J. M. Optical levitation by radiation pressure. Appl. Phys. Lett. 19, 283 (1971).Ashkin, A. Acceleration and trapping of particles by radiation pressure. Phys. Rev. Lett. 24, 156–159 (1970).Omori, R., Kobayashi, T. & Suzuki, A. Observation of a single-beam gradient-force optical trap for dielectric particles in air. Opt. Lett. 22, 816–818 (1997).Ashkin, A., Dziedzic, J. M., Bjorkholm, J. E. & Chu, S. Observation of a single-beam gradient force optical trap for dielectric particles. Opt. Lett. 11, 288–290 (1986).Ashkin, A., Dziedzic, J. M. & Yamane, T. Optical trapping and manipulation of single cells using infrared laser beams. Nature 330, 769–771 (1987).Bagnato, V. S. et al. Continuous stopping and trapping of neutral atoms. Phys. Rev. Lett. 58, 2194–2197 (1987).Phillips, W. D. Nobel lecture: laser cooling and trapping of neutral atoms. Rev. Mod. Phys. 70, 721–741 (1998).Wang, M. M. et al. Microfluidic sorting of mammalian cells by optical force switching. Nat. Biotechnol. 23, 83–87 (2005).Dholakia, K. & Čižmár, T. Shaping the future of manipulation. Nat. Photon. 5, 335–342 (2011).Zhao, R., Zhou, J., Koschny, T., Economou, E. N. & Soukoulis, C. M. Repulsive Casimir force in chiral metamaterials. Phys. Rev. Lett. 103, 103602 (2009).Leonhardt, U. & Philbin, T. G. Quantum levitation by left-handed metamaterials. New J. Phys. 9, 254–254 (2007).Ginis, V., Tassin, P., Soukoulis, C. M. & Veretennicoff, I. Enhancing optical gradient forces with metamaterials. Phys. Rev. Lett. 110, 057401 (2013).Rodríguez-Fortuño, F. J., Vakil, A. & Engheta, N. Electric levitation using ɛ-near-zero metamaterials. Phys. Rev. Lett. 112, 033902 (2014).Grier, D. G. A revolution in optical manipulation. Nature 424, 810–816 (2003).Yang, X., Liu, Y., Oulton, R. F., Yin, X. & Zhang, X. Optical forces in hybrid plasmonic waveguides. Nano Lett. 11, 321–328 (2011).Oskooi, A., Favuzzi, P. A., Kawakami, Y. & Noda, S. Tailoring repulsive optical forces in nanophotonic waveguides. Opt. Lett. 36, 4638 (2011).Shalin, A. S., Ginzburg, P., Belov, P. A., Kivshar, Y. S. & Zayats, A. V. Nano-opto-mechanical effects in plasmonic waveguides. Laser Photon. Rev. 8, 131–136 (2014).Abajo, F. J. G., de, Brixner, T. & Pfeiffer, W. Nanoscale force manipulation in the vicinity of a metal nanostructure. J. Phys. B At. Mol. Opt. Phys. 40, S249–S258 (2007).Juan, M. L., Righini, M. & Quidant, R. Plasmon nano-optical tweezers. Nat. Photon. 5, 349–356 (2011).Beth, R. Mechanical detection and measurement of the angular momentum of light. Phys. Rev. 50, 115–125 (1936).Padgett, M. & Bowman, R. Tweezers with a twist. Nat. Photon. 5, 343–348 (2011).Liu, M., Zentgraf, T., Liu, Y., Bartal, G. & Zhang, X. Light-driven nanoscale plasmonic motors. Nat. Nanotechnol. 5, 570–573 (2010).Marston, P. L. & Crichton, J. H. Radiation torque on a sphere caused by a circularly-polarized electromagnetic wave. Phys. Rev. A 30, 2508–2516 (1984).Sokolov, I. V. The angular momentum of an electromagnetic wave, the Sadovski effect, and the generation of magnetic fields in a plasma. Phys. Uspekhi 34, 925–932 (1991).Wang, S. B. & Chan, C. T. Lateral optical force on chiral particles near a surface. Nat. Commun. 5, 3307 (2014).Hayat, A., Müller, J. P. B. & Capasso, F. Lateral chirality-sorting optical forces. doi:10.1073/pnas.1516704112 (2015).Bliokh, K. Y., Bekshaev, A. Y. & Nori, F. Extraordinary momentum and spin in evanescent waves. Nat. Commun. 5, 3300 (2014).Antognozzi, M. et al. Direct measurement of the extraordinary optical momentum using a nano-cantilever. Preprint at http://arxiv.org/abs/1506.04248 (2015).Bekshaev, A. Y., Bliokh, K. Y. & Nori, F. Transverse spin and momentum in two-wave interference. Phys. Rev. X 5, 011039 (2015).Bliokh, K. Y., Smirnova, D. & Nori, F. Quantum spin Hall effect of light. Science 348, 1448–1451 (2015).Rodríguez-Fortuño, F. J. et al. Near-field interference for the unidirectional excitation of electromagnetic guided modes. Science 340, 328–330 (2013).Kapitanova, P. V. et al. Photonic spin Hall effect in hyperbolic metamaterials for polarization-controlled routing of subwavelength modes. Nat. Commun. 5, 3226 (2014).Bliokh, K. Y., Rodríguez-Fortuño, F. J., Nori, F. & Zayats, A. V. Spin-orbit interactions of light. Preprint at http://arxiv.org/abs/1505.02864 (2015).O’Connor, D., Ginzburg, P., Rodríguez-Fortuño, F. J., Wurtz, G. A. & Zayats, A. V. Spin–orbit coupling in surface plasmon scattering by nanostructures. Nat. Commun. 5, 5327 (2014).Neugebauer, M., Bauer, T., Banzer, P. & Leuchs, G. Polarization tailored light driven directional optical nanobeacon. Nano Lett. 14, 2546–2551 (2014).Mueller, J. P. B. & Capasso, F. Asymmetric surface plasmon polariton emission by a dipole emitter near a metal surface. Phys. Rev. B 88, 121410 (2013).Xi, Z. et al. Controllable directive radiation of a circularly polarized dipole above planar metal surface. Opt. Express 21, 30327 (2013).Carbonell, J. et al. Directive excitation of guided electromagnetic waves through polarization control. Phys. Rev. B 89, 155121 (2014).Young, A. B. et al. Polarization engineering in photonic crystal waveguides for spin-photon entanglers. Phys. Rev. Lett. 115, 153901 (2015).Mitsch, R., Sayrin, C., Albrecht, B., Schneeweiss, P. & Rauschenbeutel, A. Quantum state-controlled directional spontaneous emission of photons into a nanophotonic waveguide. Nat. Commun. 5, 5713 (2014).Le Kien, F. & Rauschenbeutel, A. Anisotropy in scattering of light from an atom into the guided modes of a nanofiber. Phys. Rev. A 90, 023805 (2014).Luxmoore, I. J. et al. Interfacing spins in an InGaAs quantum dot to a semiconductor waveguide circuit using emitted photons. Phys. Rev. Lett. 110, 037402 (2013).Rodríguez-Fortuño, F. J. et al. Universal method for the synthesis of arbitrary polarization states radiated by a nanoantenna. Laser Photon. Rev. 8, L27–L31 (2014).Rodríguez-Fortuño, F. J., Barber-Sanz, I., Puerto, D., Griol, A. & Martinez, A. Resolving light handedness with an on-chip silicon microdisk. ACS Photon. 1, 762–767 (2014).Petersen, J., Volz, J. & Rauschenbeutel, A. Chiral nanophotonic waveguide interface based on spin-orbit interaction of light. Science 346, 67–71 (2014).Xi, Z., Lu, Y., Yu, W., Wang, P. & Ming, H. Unidirectional surface plasmon launcher: rotating dipole mimicked by optical antennas. J. Opt. 16, 105002 (2014).Frisch, R. Experimental demonstration of Einstein’s radiation recoil. Zeitschrift für Phys. 86, 42–45 (1933).Wylie, J. M. & Sipe, J. E. Quantum electrodynamics near an interface. II. Phys. Rev. A 32, 2030–2043 (1985).Fichet, M., Schuller, F., Bloch, D. & Ducloy, M. van der Waals interactions between excited-state atoms and dispersive dielectric surfaces. Phys. Rev. A 51, 1553–1564 (1995).Failache, H., Saltiel, S., Fichet, M., Bloch, D. & Ducloy, M. Resonant van der Waals repulsion between excited Cs atoms and sapphire surface. Phys. Rev. Lett. 83, 5467–5470 (1999).Gordon, J. P. & Ashkin, A. Motion of atoms in a radiation trap. Phys. Rev. A 21, 1606–1617 (1980).Chaumet, P. C. & Nieto-Vesperinas, M. Time-averaged total force on a dipolar sphere in an electromagnetic field. Opt. Lett. 25, 1065–1067 (2000).Ishimaru, A. Electromagnetic Wave Propagation, Radiation, and Scattering Prentice Hall (1990).Söllner, I., Mahmoodian, S., Javadi, A. & Lodahl, P. A chiral spin-photon interface for scalable on-chip quantum-information processing. Preprint at http://arxiv.org/abs/1406.4295 (2014).Rotenberg, N. et al. Magnetic and electric response of single subwavelength holes. Phys. Rev. B Condens. Matter Mater. Phys. 88, 241408 (2013).Sukhov, S., Kajorndejnukul, V. & Dogariu, A. Dynamic Consequences of Optical Spin-Orbit Interaction. Preprint at http://arxiv.org/abs/1504.01766 (2015).Scheel, S., Buhmann, S. Y., Clausen, C. & Schneeweiss, P. Directional spontaneous emission and lateral Casimir-Polder force on an atom close to a nanofiber. Preprint at http://arxiv.org/abs/1505.01275 (2015).Rodríguez-Fortuño, F. J., Engheta, N., Martínez, A. & Zayats, A. V. Lateral Forces Acting on Particles Near a Surface Under Circularly Polarized Illumination. in 5th Inte rnational Topical Meeting on Nanophotonics and Metamaterials (Nanometa) (2-914771-91-6, Seefeld, Austria 2015).Bochenkov, V. et al. Applications of plasmonics: general discussion. Faraday Discuss. 178, 435–466 (2015).Dogariu, A. & Schwartz, C. Conservation of angular momentum of light in single scattering. Opt. Express 14, 8425–8433 (2006).Haefner, D., Sukhov, S. & Dogariu, A. Spin hall effect of light in spherical geometry. Phys. Rev. Lett. 102, 123903 (2009).Bliokh, K. Y. et al. Spin-to-orbit angular momentum conversion in focusing, scattering, and imaging systems. Opt. Express 19, 26132–26149 (2011)

Energy access is needed to maintain health during pandemics

Energy plays a central role in responding to emergencies such as the COVID-19 pandemic, from ensuring adequate healthcare services to supporting households during lockdowns. Protecting the renewable energy industry and its contribution to providing sustainable energy access for all must be an urgent priority in the current crisis

CA19-9 Normalization During Pre-operative Treatment Predicts Longer Survival for Patients with Locally Progressed Pancreatic Cancer

BACKGROUND: Compared to the widely-adopted 2–4 months of pre-operative therapy for patients with borderline resectable (BR) or locally advanced (LA) pancreatic ductal adenocarcinoma (PDAC), our institution tends to administer a longer duration before considering surgical resection. Using this unique approach, the aim of this study was to determine preoperative variables associated with survival. METHODS: Records from patients with BR/LA PDAC who underwent attempt at surgical resection from 1992–2014 were reviewed. RESULTS: After a median duration of 6 months of pre-operative treatment, 109 patients with BR/LA PDAC (BR 63, LA 46) were explored; 93 (85.3%) underwent pancreatectomy. Those who received at least 6 months of pre-operative treatment had longer median overall survival (OS) than those who received less (52.8 vs. 32.1 months, P=0.044). On multivariate analysis, pre-operative treatment duration was the strongest predictor of survival (hazard ratio (HR) 4.79, P=0.043). However, OS was similar in those whose CA19-9 normalized regardless of whether they received more or less than 6 months of chemotherapy (71.4 vs. 101.8 months, P=0.930). CONCLUSIONS: Pre-operative CA19-9 decline can guide treatment duration in patients with BR/LA PDAC. We endorse 6 months of therapy except in those patients whose values normalize, where surgery can be considered after a shorter course