Using the TIMED Doppler interferometer (TIDI) mesospheric and lower thermospheric neutral‐wind multiyear data set (2002–2007) and NCAR TIME General Circulation Models (GCM) 1.2 annual run results ...(2002–2005) at the TIDI sampling points, we study the migrating diurnal tide's global distribution, interannual, and seasonal variations in connection with the mean zonal wind interannual variations. A strong quasi‐biennial oscillation (QBO) effect on the diurnal tide was observed in the TIDI data and reproduced to a lesser degree in the TIME‐GCM run. The migrating diurnal tide amplitude is larger during the eastward phase of the stratospheric QBO and weaker during the westward phase. Westward mesospheric equatorial mean zonal winds appeared during the eastward phase of the stratospheric QBO (in 2002, 2004, and 2006). The strongest QBO effect on both the migrating diurnal tide and mean zonal winds was observed during the March equinox. The stronger tides may be related to the weaker gravity wave filtering in the stratosphere during the eastward phase stratospheric QBO. The TIDI data also exhibit large interhemispheric asymmetry. The westward mean zonal winds in the mesosphere appeared to be associated with the enhanced diurnal tide. The TIME‐GCM 1.2 diurnal tide amplitudes are in general smaller than those observed by the TIDI instrument. Limited vertical spatial resolution for the TIME‐CGM 1.2 is suggested as the cause. Future improvements are expected with a higher spatial resolution in the model.
The Whole Atmosphere Community Climate Model eXtended is used to investigate the extent to which neglecting the realistic day‐to‐day lower atmospheric variability introduces uncertainty in the ...ionosphere response to an idealized geomagnetic storm. A 10‐member ensemble is generated by adding small temperature perturbations in the lower atmosphere 30 days prior to the imposed geomagnetic storm. Chaotic divergence, and internal atmospheric variability, leads to the geomagnetic storm occurring under an arbitrarily different, though climatically similar, atmospheric state for each ensemble member. The intra‐ensemble variability, which we characterize by the ensemble standard deviation, of the day‐to‐day change in total electron content is generally ∼10%–20% during geomagnetically quiet time. During an idealized storm with a Kp of 7 the ensemble standard deviation of the change in total electron content increases to ∼20%–40% at low and middle latitudes, with localized regions exceeding 100%. Examination of individual ensemble members illustrates that they all capture the same large‐scale features of the storm time changes in the ionosphere but can exhibit notable (50%) differences regionally, especially during later stages of the storm. The results thus demonstrate that in order to accurately capture smaller‐scale features of the upper atmosphere response to geomagnetic storms, it is necessary to include the effects of lower atmosphere variability.
Plain Language Summary
Geomagnetic storms are an important driver of variability in Earth's ionosphere and can have significant societal impacts through the ionosphere's impact on communications and navigation systems (e.g., Global Positioning System). Numerical simulations are a common tool for the specification and forecasting of the ionosphere variability driven by geomagnetic storms. Simulations have historically only used a climatological spectrum of waves propagating upward from the lower atmosphere (i.e., troposphere, stratosphere, and mesosphere; 0–100 km). This neglect of the day‐to‐day variability of wave forcing from the lower atmosphere is a potential source of uncertainty when simulating the ionosphere variability during geomagnetic storms. The present study uses a whole atmosphere model, extending from the surface to ∼500 km, to understand the uncertainty in the ionosphere response to a geomagnetic storm that is due to the day‐to‐day variability of the lower atmosphere. It is found that omitting lower atmosphere variability leads to an uncertainty in the ionosphere response to a geomagnetic storm that is typically ∼20%–40% but can be as large as 100% regionally. Incorporating the day‐to‐day variability of the lower atmosphere is thus an important factor for reducing the uncertainty in numerical models that are used to specify and forecast the near‐Earth space environment.
Key Points
WACCM‐X simulations demonstrate the impact of lower atmosphere variability during a geomagnetic storm
Uncertainty in TEC response to a geomagnetic storm due to neglecting lower atmosphere forcing is 20–40%
Simulations, and observational analyses, should account for the effects of lower atmosphere forcing
Abstract
As a novel X-ray focusing technology, lobster-eye micropore optics (MPO) feature both a wide observing field of view and true imaging capability, promising sky monitoring with significantly ...improved sensitivity and spatial resolution in soft X-rays. Since first proposed by Angel, the optics have been extensively studied, developed and trialed over the past decades. In this Letter, we report on the first-light results from a flight experiment of the Lobster Eye Imager for Astronomy, a pathfinder of the wide-field X-ray telescope of the Einstein Probe mission. The piggyback imager, launched in 2022 July, has a mostly unvignetted field of view of 18.°6 × 18.°6. Its spatial resolution is in the range of 4′–7′ in FWHM and the focal spot effective area is 2–3 cm
2
, both showing only mild fluctuations across the field of view. We present images of the Galactic center region, Sco X-1, and the diffuse Cygnus Loop nebular taken in snapshot observations over 0.5–4 keV. These are truly wide-field X-ray images of celestial bodies observed, for the first time, by a focusing imaging telescope. Initial analyses of the in-flight data show excellent agreement between the observed images and the on-ground calibration and simulations. The instrument and its characterization are briefly described, as well as the flight experiment. The results provide a solid basis for the development of the present and proposed wide-field X-ray missions using lobster-eye MPO.
Fracture liaison services (FLS), implemented in different ways and countries, are reported to be a cost-effective or even a cost-saving secondary fracture prevention strategy. This presumed favorable ...cost-benefit relationship is encouraging and lends support to expanded implementation of FLS per International Osteoporosis Foundation Best Practice Standards. This study summarizes the economic impact and cost-effectiveness of FLS implemented to reduce subsequent fractures in individuals with osteoporosis. This systematic review identified studies reporting economic outcomes for FLS in osteoporotic patients aged 50 and older through a comprehensive search of MEDLINE, EMBASE, Cochrane Central, and PubMed of studies published January, 2000 to December, 2016. Grey literature (e.g., Google scholar, conference abstracts/posters) were also hand searched through February 2017. Two independent reviewers screened titles and abstracts and conducted full-text review on qualified articles. All disagreements were resolved by discussion between reviewers to reach consensus or by a third reviewer. In total, 23 qualified studies that evaluated the economic aspects of FLS were included: 16 cost-effectiveness studies, 2 cost-benefit analyses, and 5 studies of cost savings. Patient populations varied (prior fragility fracture, non-vertebral fracture, hip fracture, wrist fracture), and FLS strategies ranged from mail-based interventions to comprehensive nurse/physician-coordinated programs. Cost-effectiveness studies were conducted in Canada, Australia, USA, UK, Japan, Taiwan, and Sweden. FLS was cost-effective in comparisons with usual care or no treatment, regardless of the program intensity or the country in which the FLS was implemented (cost/QALY from $3023–$28,800 US dollars (USD) in Japan to $14,513–$112,877 USD in USA. Several studies documented cost savings. FLS, implemented in different ways and countries, are reported to be cost-effective or even cost-saving. This presumed favorable cost-benefit relationship is encouraging and lends support to expanded implementation of FLS per International Osteoporosis Foundation Best Practice Standards.
Spin-orbit coupling is a fundamental interaction in solids that can induce a broad range of unusual physical properties, from topologically non-trivial insulating states to unconventional pairing in ...superconductors1, 2, 3, 4, 5, 6, 7. In iron-based superconductors its role has, so far, not been considered of primary importance, with models based on spin- or orbital fluctuations pairing being used most widely8, 9, 10. Using angle-resolved photoemission spectroscopy, we directly observe a sizeable spin-orbit splitting in all the main members of the iron-based superconductors. We demonstrate that its impact on the low-energy electronic structure and details of the Fermi surface topology is stronger than that of possible nematic ordering11, 12, 13. The largest pairing gap is supported exactly by spin-orbit-coupling-induced Fermi surfaces, implying a direct relation between this interaction and the mechanism of high-temperature superconductivity.
To assess the clinicopathological features, immunophenotype, molecular characteristics and differential diagnosis of primary cardiac synovial sarcoma (PCSS).
Five cases of PCSS were collected at ...Guangdong Provincial People's Hospital from 2008 to 2023, and their clinicopathological features were summarized. Immunohistochemical staining, fluorescence in-situ hybridization (FISH) and next-generation sequencing (NGS) were performed, and relevant literatures were reviewed.
The cases were found in four males and one female, ranging in ages from 16 to 51 years (median 30 years). Two cases were located in the pericardium, two in the right ventricle, and one in the left ventricle. Follow-up data were available in four cases. All the four patients died of disease at 3, 7, 13 and 26 months, respectively, after diagnosis. The tumor maximum diameter ranged from 6.0 to 14.0 cm in (mean 10.0 cm). Microscopically, three cases were monophasic and two cases were biphasic. Immunohistochemically, all cases were immunoreactive f
Whole Atmosphere Community Climate Model (WACCM) simulations are used to investigate solar and lunar tide changes in the mesosphere and lower thermosphere (MLT) that occur in response to sudden ...stratosphere warmings (SSWs). The average tidal response is demonstrated based on 23 moderate to strong Northern Hemisphere SSWs. The migrating semidiurnal lunar tide is enhanced globally during SSWs, with the largest enhancements (∼60–70%) occurring at mid to high latitudes in the Northern Hemisphere. Enhancements in the migrating solar semidiurnal tide (SW2) also occur up to an altitude of 120 km. Above this altitude, the SW2 decreases in response to SSWs. The SW2 enhancements are 40–50%, making them smaller in a relative sense than the enhancements in the migrating semidiurnal lunar tide. Changes in nonmigrating solar tides are, on average, generally small and the only nonmigrating tides that exhibit changes greater than 20% are the diurnal tide with zonal wave number 0 (D0) and the westward propagating semidiurnal tide with zonal wave number 1 (SW1). D0 is decreased by ∼20–30% at low latitudes, while SW1 exhibits a similar magnitude enhancement at mid to high latitudes in both hemispheres. The tidal changes are attributed to a combination of changes in the zonal mean zonal winds, changes in ozone forcing of the SW2, and nonlinear planetary wave‐tide interactions. We further investigate the influence of the lunar tide enhancements on generating perturbations in the low latitude ionosphere during SSWs by using the WACCM‐X thermosphere to drive an ionosphere‐electrodynamics model. For both solar maximum and solar minimum simulations, the changes in the equatorial vertical plasma drift velocity are similar to observations when the lunar tide is included in the simulations. However, when the lunar tide is removed from the simulations, the low latitude ionosphere response to SSWs is unclear and the characteristic behavior of the low latitude ionosphere perturbations that is seen in observations is no longer apparent. Our results thus indicate the importance of variability in the lunar tide during SSWs, especially for the coupling between SSWs and perturbations in the low latitude ionosphere.
Key Points
Investigate tidal variability due to SSWs based on WACCM simulations of 23 SSWs
Large changes in the migrating semidiurnal lunar and solar tides during SSWs
Changes in lunar tide are important for coupling between SSWs and ionosphere
High‐resolution Whole Atmosphere Community Climate Model with thermosphere/ionosphere extension is used to simulate the responses to the Hunga‐Tonga volcano eruption on 15 January 2022. Global ...propagation of the Lamb wave L’0 and L’1 pseudomodes are reproduced in the simulation, with the exponential growth of wave amplitudes with altitudes. The wavefront is vertical up to the lower thermosphere, and tilts outward above. These features are consistent with theoretical results. With simulated surface pressure perturbation agreeing with observations (∼100–250 Pa), thermospheric wind perturbations over 100 ms−1 are comparable with reported satellite and ground‐based observations. Traveling ionospheric disturbances in the total electron contents from the simulation show good agreement with observations, including magnitude and propagating speed and evidence of conjugacy in the first 1–2 hr after eruption. Conjugacy in E × B drift, on the other hand, is more persistent.
Plain Language Summary
As one of the most powerful volcano eruptions on record, the Hunga Tonga‐Hunga Ha'apai Volcano produces waves that ripple through the atmosphere and near‐space environment. These wave signals have been recorded by observations from instruments on the ground and from satellites, and they propagate around the Earth multiple times. This event provides a rare opportunity to study the strong and direct connection of the whole atmosphere system. The challenge is for a model to be able to represent the key processes in the whole atmosphere system and to have sufficient spatial and temporal fidelity to gain a realistic global picture of the event. This is achieved in the study by using the high‐resolution Whole Atmosphere Community Climate Model with thermosphere/ionosphere extension. The model is able to simulate the global propagation of the waves, and the model results compare favorably with observations from the surface to the thermosphere and ionosphere.
Key Points
High‐resolution Whole Atmosphere Community Climate Model with thermosphere/ionosphere extension simulation of Hunga eruption shows whole atmosphere responses
Simulated wave amplitude growth and phase structure are consistent with the theoretical prediction
Simulation results are comparable with thermospheric and ionospheric observations
This article presents a hysteretic water retention curve (WRC) and unsaturated hydraulic conductivity model for deformable soils based on the change in pore-size distribution (PSD). The PSD plays a ...decisive role in the water retention behaviour of soils. Although its evolution during deformation is rather complicated, experimental data showed that, the overall shapes and distribution characteristics of the PSD function are not significantly altered. Based on these findings, the PSD function at a deformed state is obtained by horizontal shifting, and vertical scaling of the corresponding PSD function at a reference state. On this basis, a hysteretic WRC model is formulated to account for the influences of deformation and hysteresis on the variation of saturation, using seven model parameters with clear physical meanings. The proposed model is then incorporated in the Mualem model to predict the unsaturated hydraulic conductivity for deformable soils, using only one additional parameter. A large number of published laboratory tests are used to validate the proposed model, showing that, it can reasonably capture important features of retention and permeability properties for deformable soils in most cases under consideration.
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