Spin–orbit interactions of light Bliokh, K. Y.; Rodríguez-Fortuño, F. J.; Nori, F. ...
Nature photonics,
12/2015, Letnik:
9, Številka:
12
Journal Article
Recenzirano
Light carries both spin and orbital angular momentum. These dynamical properties are determined by the polarization and spatial degrees of freedom of light. Nano-optics, photonics and plasmonics tend ...to explore subwavelength scales and additional degrees of freedom of structured -- that is, spatially inhomogeneous -- optical fields. In such fields, spin and orbital properties become strongly coupled with each other. In this Review we cover the fundamental origins and important applications of the main spin-orbit interaction phenomena in optics. These include: spin-Hall effects in inhomogeneous media and at optical interfaces, spin-dependent effects in nonparaxial (focused or scattered) fields, spin-controlled shaping of light using anisotropic structured interfaces (metasurfaces) and robust spin-directional coupling via evanescent near fields. We show that spin-orbit interactions are inherent in all basic optical processes, and that they play a crucial role in modern optics.
It is well known that the spin angular momentum of light, and therefore that of photons, is directly related to their circular polarization. Naturally, for totally unpolarized light, polarization is ...undefined and the spin vanishes. However, for non-paraxial light, the recently discovered transverse spin component, orthogonal to the main propagation direction, is largely independent of the polarization state of the wave. Here, we demonstrate, both theoretically and experimentally, that this transverse spin survives even in non-paraxial fields (for example, focused or evanescent) generated from totally unpolarized paraxial light. This counterintuitive phenomenon is closely related to the fundamental difference between the meanings of ‘full depolarization’ for two-dimensional (2D) paraxial and 3D non-paraxial fields. Our results open an avenue for studies of spin-related phenomena and optical manipulation using unpolarized light.A theoretical and experimental study of the transverse spin appearing in non-paraxial light when the source is totally unpolarized is reported, in sharp contrast to the usual longitudinal spin, which is directly related to the 2D polarization and vanishes in unpolarized fields.
The spin Hall effect leads to the separation of electrons with opposite spins in different directions perpendicular to the electric current flow because of interaction between spin and orbital ...angular momenta. Similarly, photons with opposite spins (different handedness of circular light polarization) may take different trajectories when interacting with metasurfaces that break spatial inversion symmetry or when the inversion symmetry is broken by the radiation of a dipole near an interface. Here we demonstrate a reciprocal effect of spin-orbit coupling when the direction of propagation of a surface plasmon wave, which intrinsically has unusual transverse spin, determines a scattering direction of spin-carrying photons. This spin-orbit coupling effect is an optical analogue of the spin injection in solid-state spintronic devices (inverse spin Hall effect) and may be important for optical information processing, quantum optical technology and topological surface metrology.
Closed-shell carbon nanostructures, such as carbon onions, have been shown to act as self-contracting high-pressure cells under electron irradiation. We report that controlled irradiation of ...multiwalled carbon nanotubes can cause large pressure buildup within the nanotube cores that can plastically deform, extrude, and break solid materials that are encapsulated inside the core. We further showed by atomistic simulations that the internal pressure inside nanotubes can reach values higher than 40 gigapascals. Nanotubes can thus be used as robust nanoscale jigs for extruding and deforming hard nanomaterials and for modifying their properties, as well as templates for the study of individual nanometer-sized crystals under high pressure.
The affinities of extinct organisms are often difficult to resolve using morphological data alone. Chemical analysis of carbonaceous specimens can complement traditional approaches, but the search ...for taxon-specific signals in ancient, thermally altered organic matter is challenging and controversial, partly because suitable positive controls are lacking. Here, we show that non-destructive Fourier Transform Infrared Spectroscopy (FTIR) resolves in-situ molecular fingerprints in the famous 407 Ma Rhynie chert fossil assemblage of Aberdeenshire, Scotland, an important early terrestrial Lagerstätte. Remarkably, unsupervised clustering methods (principal components analysis and K-mean) separate the fossil spectra naturally into eukaryotes and prokaryotes (cyanobacteria). Additional multivariate statistics and machine-learning approaches also differentiate prokaryotes from eukaryotes, and discriminate eukaryotic tissue types, despite the overwhelming influence of silica. We find that these methods can clarify the affinities of morphologically ambiguous taxa; in the Rhynie chert for example, we show that the problematic "nematophytes" have a plant-like composition. Overall, we demonstrate that the famously exquisite preservation of cells, tissues and organisms in the Rhynie chert accompanies similarly impressive preservation of molecular information. These results provide a compelling positive control that validates the use of infrared spectroscopy to investigate the affinity of organic fossils in chert.
Interbedded contourites, turbidites and pelagites are commonplace in many deep‐water slope environments. However, the distinction between these different facies remains a source of controversy. This ...detailed study of calcareous contourites and associated deep‐marine facies from an Eocene–Miocene sedimentary succession on Cyprus clearly documents the diagnostic value of microfacies in this debate. In particular, the variability of archetypical bi‐gradational contourite sequences and their internal subdivision (bedding, layering and lamination) are explored. Contourites can be distinguished from turbidites, pelagites and hemipelagites by means of carbonate microfacies in combination with bed‐scale characteristics. Particle composition provides valuable information on sediment provenance. Depositional texture, determined by the ratio between carbonate mud and bioclasts, is crucial for identifying bi‐gradational sequences in both muddy and sandy contourites, and normally‐graded sequences in turbidite beds. Equally important are the type and preservation of traction structures, as well as the temporality and impact of bioturbation. Shell fragmentation under conditions of increased hydrodynamic agitation (textural inversion) is recognized as a carbonate‐specific feature of bioclastic sandy contourites.
In this paper, we report on the fourth soft gamma-ray source catalog obtained with the IBIS gamma-ray imager on board the INTEGRAL satellite. The scientific data set is based on more than 70 Ms of ...high-quality observations performed during the first five and a half years of the Core Program and public observations. Compared to previous IBIS surveys, this catalog includes a substantially increased coverage of extragalactic fields, and comprises more than 700 high-energy sources detected in the energy range 17-100 keV, including both transients and faint persistent objects that can only be revealed with longer exposure times. A comparison is provided with the latest Swift/BAT survey results. Based on observations with INTEGRAL, an ESA project with instruments and Science Data Centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), Czech Republic, and Poland, and with the participation of Russia and the USA.
Colon cancer is the third most frequent cancer and the fourth most common cause of cancer-related mortality worldwide and the standard therapy is surgical resection plus adjuvant chemotherapy. ...Photodynamic therapy (PDT) has been proposed as an adjuvant therapy because it can prevent the tumor recurrence after surgical excision in colon cancer patients. Hypoxia is a common feature in solid tumors and leads to chemo/radioresistance. Recently, it has been shown that in response to hypoxia, cells can induce HIF-1α-mediated autophagy to survive in this hostile microenvironment. Moreover, hypoxia and autophagy have been implicated in the resistance to antitumor PDT. However, the molecular signals by which HIF-1α induces autophagy in the PDT context have not been studied yet. Here we evaluate the interplay between HIF-1α and autophagy as well as the underlying mechanism in the PDT resistance of colon cancer cells. Our study demonstrates that HIF-1α stabilization significantly increases VMP1-related autophagy through binding to hypoxia responsive elements in the VMP1 promoter. We show that HIF-1α-induced autophagy increases colon cancer cell survival as well as decreases cell death after PDT. Moreover, here we demonstrate that HIF-1α-induced autophagy is mediated by VMP1 expression, since the downregulation of VMP1 by the RNA interference strategy reduces HIF-1α-induced autophagy and cell survival after PDT. In conclusion, PDT induces autophagy as a survival mechanism and the induction of the novel HIF-1α/VMP1-autophagic pathway may explain, at least in part, the resistance of colon cancer cells to PDT. The knowledge of the molecular mechanisms involved in PDT resistance may lead to more accurate therapeutic strategies.
Background
Respiratory viruses are the leading cause of lower respiratory tract infection (LRTI) and hospitalisation in infants and young children. Respiratory syncytial virus (RSV) is the main ...infectious agent in this population. Palivizumab is administered intramuscularly every month during five months in the first RSV season to prevent serious RSV LRTI in children. Given its high cost, it is essential to know if palivizumab continues to be effective in preventing severe RSV disease in children.
Objectives
To assess the effects of palivizumab for preventing severe RSV infection in children.
Search methods
We searched CENTRAL, MEDLINE, three other databases and two trials registers to 14 October 2021, together with reference checking, citation searching and contact with study authors to identify additional studies. We searched Embase to October 2020, as we did not have access to this database for 2021.
Selection criteria
We included randomised controlled trials (RCTs), including cluster‐RCTs, comparing palivizumab given at a dose of 15 mg/kg once a month (maximum five doses) with placebo, no intervention or standard care in children 0 to 24 months of age from both genders, regardless of RSV infection history.
Data collection and analysis
We used Cochrane’s Screen4Me workflow to help assess the search results. Two review authors screened studies for selection, assessed risk of bias and extracted data. We used standard Cochrane methods. We used GRADE to assess the certainty of the evidence. The primary outcomes were hospitalisation due to RSV infection, all‐cause mortality and adverse events. Secondary outcomes were hospitalisation due to respiratory‐related illness, length of hospital stay, RSV infection, number of wheezing days, days of supplemental oxygen, intensive care unit length of stay and mechanical ventilation days.
Main results
We included five studies with a total of 3343 participants. All studies were parallel RCTs, assessing the effects of 15 mg/kg of palivizumab every month up to five months compared to placebo or no intervention in an outpatient setting, although one study also included hospitalised infants. Most of the included studies were conducted in children with a high risk of RSV infection due to comorbidities like bronchopulmonary dysplasia and congenital heart disease. The risk of bias of outcomes across all studies was similar and predominately low.
Palivizumab reduces hospitalisation due to RSV infection at two years' follow‐up (risk ratio (RR) 0.44, 95% confidence interval (CI) 0.30 to 0.64; 5 studies, 3343 participants; high certainty evidence). Based on 98 hospitalisations per 1000 participants in the placebo group, this corresponds to 43 (29 to 62) per 1000 participants in the palivizumab group. Palivizumab probably results in little to no difference in mortality at two years' follow‐up (RR 0.69, 95% CI 0.42 to 1.15; 5 studies, 3343 participants; moderate certainty evidence). Based on 23 deaths per 1000 participants in the placebo group, this corresponds to 16 (10 to 27) per 1000 participants in the palivizumab group. Palivizumab probably results in little to no difference in adverse events at 150 days' follow‐up (RR 1.09, 95% CI 0.85 to 1.39; 3 studies, 2831 participants; moderate certainty evidence). Based on 84 cases per 1000 participants in the placebo group, this corresponds to 91 (71 to 117) per 1000 participants in the palivizumab group. Palivizumab probably results in a slight reduction in hospitalisation due to respiratory‐related illness at two years' follow‐up (RR 0.78, 95% CI 0.62 to 0.97; 5 studies, 3343 participants; moderate certainty evidence). Palivizumab may result in a large reduction in RSV infection at two years' follow‐up (RR 0.33, 95% CI 0.20 to 0.55; 3 studies, 554 participants; low certainty evidence). Based on 195 cases of RSV infection per 1000 participants in the placebo group, this corresponds to 64 (39 to 107) per 1000 participants in the palivizumab group. Palivizumab also reduces the number of wheezing days at one year's follow‐up (RR 0.39, 95% CI 0.35 to 0.44; 1 study, 429 participants; high certainty evidence).
Authors' conclusions
The available evidence suggests that prophylaxis with palivizumab reduces hospitalisation due to RSV infection and results in little to no difference in mortality or adverse events. Moreover, palivizumab results in a slight reduction in hospitalisation due to respiratory‐related illness and may result in a large reduction in RSV infections. Palivizumab also reduces the number of wheezing days. These results may be applicable to children with a high risk of RSV infection due to comorbidities.
Further research is needed to establish the effect of palivizumab on children with other comorbidities known as risk factors for severe RSV disease (e.g. immune deficiencies) and other social determinants of the disease, including children living in low‐ and middle‐income countries, tropical regions, children lacking breastfeeding, living in poverty, or members of families in overcrowded situations.
The Andromeda Galaxy recurrent nova M31N 2008-12a had been caught in eruption eight times. The inter-eruption period of M31N 2008-12a is ~1 yr, making it the most rapidly recurring system known, and ...a strong single-degenerate Type Ia supernova progenitor candidate. Following the 2013 eruption, a campaign was initiated to detect the predicted 2014 eruption and to then perform high cadence optical photometric and spectroscopic monitoring using ground-based telescopes, along with rapid UV and X-ray follow-up with the Swift satellite. Here we report the results of a high cadence multi-colour optical monitoring campaign, the spectroscopic evolution, and the UV photometry. We also discuss tantalising evidence of a potentially related, vastly-extended, nebulosity. The 2014 eruption was discovered, before optical maximum, on October 2, 2014. We find that the optical properties of M31N 2008-12a evolve faster than all Galactic recurrent novae known, and all its eruptions show remarkable similarity both photometrically and spectroscopically. Optical spectra were obtained as early as 0.26 days post maximum, and again confirm the nova nature of the eruption. A significant deceleration of the inferred ejecta expansion velocity is observed which may be caused by interaction of the ejecta with surrounding material,possibly a red giant wind. We find a low ejected mass and low ejection velocity, which are consistent with high mass-accretion rate, high mass white dwarf, and short recurrence time models of novae. We encourage additional observations, especially around the predicted time of the next eruption, towards the end of 2015.
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