The spectral properties of the transverse magneto-optical Kerr effect (TMOKE) in periodic metal-dielectric hybrid structures are studied, in particular with respect to the achievable magnitude. It is ...shown that the TMOKE is sensitive to the magneto-optical activity of the bismuth-substituted rare-earth iron garnet, which is used as a dielectric material in the investigated structures. For samples with larger Bi substitution level and, consequently, larger gyration constant, the magnitude of the TMOKE increases and reaches 13% in the case of a Bi1.8Lu1.2Fe3.6Al1.4O12 magnetic film. Further, it is demonstrated that the TMOKE vanishes at the high-symmetry points of the Brillouin zone (at the Γ and X points). The main enhancement of the TMOKE takes place near the resonances of the surface plasmon polaritons (SPPs) at the metal magnetic-dielectric interface. However, near the degenerate resonances of the SPPs at the air metal and metal magnetic-dielectric interfaces the TMOKE is increased by the air metal SPPs as well. This phenomenon is explained in terms of a coupled oscillator model.
We present the study of the waveguide modes of one-dimensional magnetic photonic crystals with in-plane-magnetized layers. There is a magneto-optical effect of nonreciprocity for the TM-modes ...propagating along the layers perpendicularly to the magnetization. Due to the non-reciprocity the phase velocity of the modes changes with magnetization reversal. Comparison of the effect in the non-magnetic photonic crystal with additional magnetic layer on top and a magnetophotonic crystal with altering magnetic layers shows that the effect is greater in the first case due to the higher asymmetry of the claddings of the magnetic layer. This effect is important for the light modulation with external magnetic field in waveguide structures and may be used for design of novel types of the magneto-optical devices, sensors of magnetic field or biosensors.
We analyze waveguide modes in 1D photonic crystals containing layers magnetized in the plane. It is shown that the magnetooptical nonreciprocity effect emerges in such structures during the ...propagation of waveguide modes along the layers and perpendicularly to the magnetization. This effect involves a change in the phase velocity of the mode upon reversal of the direction of magnetization. Comparison of the effects in a nonmagnetic photonic crystal with an additional magnetic layer and in a photonic crystal with magnetic layers shows that the magnitude of this effect is several times larger in the former case in spite of the fact that the electromagnetic field of the modes in the latter case is localized in magnetic regions more strongly. This is associated with asymmetry of the dielectric layers contacting with the magnetic layer in the former case. This effect is important for controlling waveguide structure modes with the help of an external magnetic field.
We discuss the results of gravimetric and satellite geodetic measurements at the Zapolyarnoye and Yamburgskoye gas and oil deposits in Transpolar Western Siberia in subarctic zone of Yamal-Nenets ...autonomous okrug. The development of mineral deposits and large number of pipelines require monitoring of recent motions of the Earth’s surface. Displacements and other phenomenon were studied by satellite geodesy and absolute gravimetry. It is now possible to obtain the kinematic parameters (rates of subsidence and horizontal motion) and addition information on fluid motion into the layers of the deposits. The ground displacements rate in different short periods recorded at large man-made objects are shown. Rates for hydroobjects are estimated at 5 mm/yr. The gravimetry and satellite geodesy results obtained at the Zapolyarnoye deposit in the northern part of Western Siberia were analyzed. Subsidence rates of 21–23 mm/yr were estimated. An increase in gravity of up to 7 µGal were recorded at the deposits (2006–2008). In this case, the increased gravity is related to surface subsidence (with a normal vertical gradient). Subsidence rates of 16–21 mm/yr were estimated at the Yamburgskoye field. This result is consistent with the rates at Zapolyarnoye. The horizontal rates and orientation differed at different deposits.
The modern gravimetry methods are capable of measuring gravity with an accuracy of up to 10
–10
of the normal value, which is commensurate with the accuracy of the up-to-date methods of displacement ...measurements by satellite geodesy. Significant changes, e.g., in the coseismic displacements of the Earth’s surface are recorded in the zones of large earthquakes. These changes should manifest themselves in the variations of gravity. Absolute measurements have been conducted by various modifications of absolute ballistic gravimeters GABL since the mid-1970s at the Klyuchi point (Novosibirsk) in the south of the West Siberian plate. Monitoring observations have been taking place in the seismically active regions since the 1990s. In this paper we consider the results of the long-term measurements of the variations in gravity and recent crustal displacements for different types of earthquakes (the zones of shear, extension, and compression). In the seismically active areas in the east of Russia, the longest annual series of absolute measurements starting from 1992 was recorded in the southeastern segment of Baikal region. In this area, the Kultuk earthquake with magnitude 6.5 occurred on August 27, 2008, at a distance of 25 km from the observation point of the Talaya seismic station. The measurements in Gornyi (Mountainous) Altai have been conducted since 2000. A strikeslip earthquake with magnitude 7.5 took place in the southern segment of the region on September 27, 2003. The effects of the catastrophic
M
= 9.0 Tohoku, Japan, earthquake of March 11, 2011 were identified in Primor’e in the far zone of the event. The empirical data are consistent with the results of modeling based on the seismological data. The coseismic variations in gravity are caused by the combined effect of the changes in the elevation of the observation point and crustal deformation.
Objective
To describe differences in outcomes between pregnant women with and without coronavirus dsease 2019 (COVID‐19).
Design
Prospective cohort study of pregnant women consecutively admitted for ...delivery, and universally tested via nasopharyngeal (NP) swab for severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) using reverse transcription–polymerase chain reaction. All infants of mothers with COVID‐19 underwent SARS‐CoV‐2 testing.
Setting
Three New York City hospitals.
Population
Pregnant women >20 weeks of gestation admitted for delivery.
Methods
Data were stratified by SARS‐CoV‐2 result and symptomatic status, and were summarised using parametric and nonparametric tests.
Main outcome measures
Prevalence and outcomes of maternal COVID‐19, obstetric outcomes, neonatal SARS‐CoV‐2, placental pathology.
Results
Of 675 women admitted for delivery, 10.4% were positive for SARS‐CoV‐2, of whom 78.6% were asymptomatic. We observed differences in sociodemographics and comorbidities among women with symptomatic COVID‐10 versus asymptomatic COVID‐19 versus no COVID‐19. Caesarean delivery rates were 46.7% in symptomatic COVID‐19, 45.5% in asymptomatic COVID‐19 and 30.9% in women without COVID‐19 (P = 0.044). Postpartum complications (fever, hypoxia, readmission) occurred in 12.9% of women with COVID‐19 versus 4.5% of women without COVID‐19 (P < 0.001). No woman required mechanical ventilation, and no maternal deaths occurred. Among 71 infants tested, none were positive for SARS‐CoV‐2. Placental pathology demonstrated increased frequency of fetal vascular malperfusion, indicative of thrombi in fetal vessels, in women with COVID‐19 versus women without COVID‐19 (48.3% versus 11.3%, P < 0.001).
Conclusion
Among pregnant women with COVID‐19 at delivery, we observed increased caesarean delivery rates and increased frequency of maternal complications in the postpartum period. Additionally, intraplacental thrombi may have maternal and fetal implications for COVID‐19 remote from delivery.
Tweetable
COVID‐19 at delivery: more caesarean deliveries, postpartum complications and intraplacental thrombi.
Tweetable
COVID‐19 at delivery: more caesarean deliveries, postpartum complications and intraplacental thrombi.
This article includes Author Insights, a video available at https://vimeo.com/rcog/authorinsights16403
A new version of the Russian absolute field gravimeter GABL-M with a green Nd:YAG laser developed at the Institute of Automation and Electrometry of the Siberian Branch of the Russian Academy of ...Sciences is discussed. The gravimeter is described briefly and its technical characteristics are given, along with some results from the first measurements under various conditions. (Field measurements were made in a tundra region.)
A method for vertical adjustment of displacement control of measuring beam flare spot for absolute laser ballistic gravimeters is described. This method is based on video registration of displacement ...trajectory of the measuring beam reflected from the corner reflector during the free fall of a body. The values and directions of the measuring beam angle relative to the vertical were determined using frame-by-frame processing of the obtained videorecording. It is experimentally established that the error of vertical adjustment does not exceed
rad
PDF
