In atmospheric and space environment studies it is key to understand and to quantify the coupling of atmospheric regions and the solar impacts on the whole atmosphere system. There is thus a need for ...a numerical model that encompasses the whole atmosphere and can self‐consistently simulate the dynamic, physical, chemical, radiative, and electrodynamic processes that are important for the Sun‐Earth system. This is the goal for developing the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM). In this work, we report the development and preliminary validation of the thermospheric extension of WACCM (WACCM‐X), which extends from the Earth's surface to the upper thermosphere. The WACCM‐X uses the finite volume dynamical core from the NCAR Community Atmosphere Model and includes an interactive chemistry module resolving most known neutral chemistry and major ion chemistry in the middle and upper atmosphere, and photolysis and photoionization. Upper atmosphere processes, such as nonlocal thermodynamic equilibrium, radiative transfer, auroral processes, ion drag, and molecular diffusion of major and minor species, have been included in the model. We evaluate the model performance by examining the quantities essential for the climate and weather of the upper atmosphere: the mean compositional, thermal, and wind structures from the troposphere to the upper thermosphere and their variability on interannual, seasonal, and daily scales. These quantities are compared with observational and previous model results.
We report results from a self‐consistent global simulation model in which a large‐scale equatorial plasma bubble (EPB) forms during a midnight temperature maximum (MTM). The global model comprises ...the ionospheric code SAMI3 and the atmosphere/thermosphere code WACCM‐X. We consider solar minimum conditions for the month of August. We show that an EPB forms during an MTM in the Pacific sector and is caused by equatorward neutral wind flows. Although this is consistent with the theoretical result that a meridional neutral wind (V) with a negative gradient (∂V/∂θ < 0) is a destabilizing influence Huba & Krall, 2013, https://doi.org/10.1002/grl.50292 (where a northward meridional neutral wind V is positive and θ is the latitude and increases in the northward direction), we find that the primary cause of the EPB is the large decrease in the Pedersen conductance caused by the equatorward winds.
Plain Language Summary
The equatorial ionosphere often develops electron density irregularities at night in the altitude range 300–1,000 km. This phenomenon is known as equatorial spread F. A leading candidate to explain the generation of these irregularities is the generalized Rayleigh‐Taylor instability (GRTI). The phenomenon usually occurs after sunset but under certain conditions it can occur around midnight. In this paper, using the coupled ionosphere/thermosphere model SAMI3/WACCM‐X, we show that it can occur during a midnight temperature maximum where the neutral thermosphere temperature increases near the equator. This is associated with equatorward neutral wind flows that change the conductance of the ionosphere and leads to an increase in the growth rate of the GRTI and the development of a large equatorial plasma bubble.
Key Points
An equatorial plasma bubble can develop during a midnight temperature maximum in the ionosphere
Equatorward winds reduce the Pedersen conductance that enhances the growth rate of the generalized Rayleigh‐Taylor instability
The results are based on the coupled ionosphere/thermosphere model SAMI3/WACCM‐X
Summary
Background
Tinea capitis is still common in developing countries, such as China. Its pathogen spectrum varies across regions and changes over time.
Objectives
This study aimed to clarify the ...current epidemiological characteristics and pathogen spectrum of tinea capitis in China.
Methods
A multicentre, prospective descriptive study involving 29 tertiary hospitals in China was conducted. From August 2019 to July 2020, 611 patients with tinea capitis were enrolled. Data concerning demography, risk factors and fungal tests were collected. When necessary, the pathogens were further identified by morphology or molecular sequencing in the central laboratory.
Results
Among all enrolled patients, 74·1% of the cases were in patients aged 2–8 years. The children with tinea capitis were mainly boys (56·2%) and were more likely than adults to have a history of animal contact (57·4% vs. 35·3%, P = 0·012) and zoophilic dermatophyte infection (73·5% vs. 47%). The adults were mainly female (83%) and were more likely than children to have anthropophilic agent infection (53% vs. 23·9%). The most common pathogen was zoophilic Microsporum canis (354, 65·2%), followed by anthropophilic Trichophyton violaceum (74, 13·6%). In contrast to the eastern, western and northeastern regions, where zoophilic M. canis predominated, anthropophilic T. violaceum predominated in central China (69%, P < 0·001), where the patients had the most tinea at other sites (20%) and dermatophytosis contact (26%) but the least animal contact (39%). Microsporum ferrugineum was the most common anthropophilic agent in the western area, especially in Xinjiang province.
Conclusions
Boys aged approximately 5 years were the most commonly affected group. Dermatologists are advised to pay more attention to the different transmission routes and pathogen spectra in different age groups from different regions.
What is already known about this topic?
Tinea capitis is an infection of the scalp and hair caused by dermatophytes and is still common in developing countries. Prepubertal children are mainly affected.
The pathogen spectrum of tinea capitis varies across different geographical areas and changes over time.
Nationwide prospective epidemiological surveys of tinea capitis in China are rare and out of date.
What does this study add?
This study provides data concerning the epidemiological characteristics and pathogen spectrum of tinea capitis in contemporary China.
Boys aged approximately 5 years were most commonly affected and were more likely than adults to have zoophilic dermatophyte infection.
The main pathogens of tinea capitis in China are zoophilic dermatophytes, mainly Microsporum canis. In contrast to the other regions, the predominant pathogens in central China are anthropophilic dermatophytes.
Plain language summary available online
Here, we describe a serological enzyme-linked immunosorbent assay for the screening and identification of human SARS-CoV-2 seroconverters. This assay does not require the handling of infectious ...virus, can be adjusted to detect different antibody types in serum and plasma and is amenable to scaling. Serological assays are of critical importance to help define previous exposure to SARS-CoV-2 in populations, identify highly reactive human donors for convalescent plasma therapy and investigate correlates of protection.
To investigate ionosphere variability during the 2009 sudden stratosphere warming (SSW), we present simulation results that combine the Whole Atmosphere Community Climate Model Extended version and ...the thermosphere‐ionosphere‐mesosphere electrodynamics general circulation model (TIME‐GCM). The simulations reveal notable enhancements in both the migrating semidiurnal solar (SW2) and lunar (M2) tides during the SSW. The SW2 and M2 amplitudes reach ∼50 m s−1 and ∼40 m s−1, respectively, in zonal wind at E region altitudes. The dramatic increase in the M2 at these altitudes influences the dynamo generation of electric fields, and the importance of the M2 on the ionosphere variability during the 2009 SSW is demonstrated by comparing simulations with and without the M2. TIME‐GCM simulations that incorporate the M2 are found to be in good agreement with Jicamarca Incoherent Scatter Radar vertical plasma drifts and Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) observations of the maximum F region electron density. The agreement with observations is worse if the M2 is not included in the simulation, demonstrating that the lunar tide is an important contributor to the ionosphere variability during the 2009 SSW. We additionally investigate sources of the F region electron density variability during the SSW. The primary driver of the electron density variability is changes in electric fields. Changes in meridional neutral winds and thermosphere composition are found to also contribute to the electron density variability during the 2009 SSW. The electron density variability for the 2009 SSW is therefore not solely due to variability in electric fields as previously thought.
Key Points
Lunar tide is important for simulating ionosphere during the 2009 SSW
Electric field changes are primary cause of electron density variability
Meridional winds and thermosphere composition also influence electron density
The existence of possible massive white dwarfs more than the Chandrasekhar limit (1.45 M⊙, in which M⊙ is mass of the sun) is a challenging topic. In this regard, and motivated by the important ...effect of massive graviton on the structure of white dwarfs, we study the white dwarfs in Vegh's massive gravity which is known as one of theories of de Rham, Gabadadze, and Tolley (dRGT) like massive gravity. First, we consider the modified Tolman-Oppenheimer-Volkoff equation in this theory of massive gravity and solve it numerically by using the Chandrasekhar's equation of state. Our results show that the maximum mass of white dwarfs in massive gravity can be more than the Chandrasekhar limit (M>1.45 M⊙), and this result imposes some constraints on parameters of massive gravity. Then, we investigate the effects of various parameters on other properties of the white dwarfs such as mass-radius relation, mass-central density relation, Schwarzschild radius, average density, and Kretschmann scalar. Next, we study dynamical stability condition for super-Chandrasekhar white dwarfs and show that these massive compact objects enjoy dynamical stability. Finally, in order to have a better insight, we compare the super-Chandrasekhar white dwarfs with the obtained massive neutron stars in dRGT like massive theory of gravity.
Abstract
α
-RuCl
3
is a major candidate for the realization of the Kitaev quantum spin liquid, but its zigzag antiferromagnetic order at low temperatures indicates deviations from the Kitaev model. ...We have quantified the spin Hamiltonian of
α
-RuCl
3
by a resonant inelastic x-ray scattering study at the Ru
L
3
absorption edge. In the paramagnetic state, the quasi-elastic intensity of magnetic excitations has a broad maximum around the zone center without any local maxima at the zigzag magnetic Bragg wavevectors. This finding implies that the zigzag order is fragile and readily destabilized by competing ferromagnetic correlations. The classical ground state of the experimentally determined Hamiltonian is actually ferromagnetic. The zigzag state is stabilized by quantum fluctuations, leaving ferromagnetism – along with the Kitaev spin liquid – as energetically proximate metastable states. The three closely competing states and their collective excitations hold the key to the theoretical understanding of the unusual properties of
α
-RuCl
3
in magnetic fields.
Over the past decade, efforts have been made to develop nondestructive techniques for three-dimensional (3D) grain-orientation mapping in crystalline materials. 3D x-ray diffraction microscopy and ...differential-aperture x-ray microscopy can now be used to generate 3D orientation maps with a spatial resolution of 200 nanometers (nm). We describe here a nondestructive technique that enables 3D orientation mapping in the transmission electron microscope of mono- and multiphase nanocrystalline materials with a spatial resolution reaching 1 nm. We demonstrate the technique by an experimental study of a nanocrystalline aluminum sample and use simulations to validate the principles involved.
The metallic interface between insulating LaAlO3 and SrTiO3 opens up the field of oxide electronics. With more than a decade of researches on this heterostructure, the origin of the interfacial ...conductivity, however, remains unsettled. Here we resolve this long-standing puzzle by atomic-scale observation of electron-gas formation for screening hidden lattice instabilities, rejuvenated near the interface by epitaxial strain. Using atomic-resolution imaging and electron spectroscopy, the generally accepted notions of polar catastrophe and cation intermixing for the metallic interface are discounted. Instead, the conductivity onset at the critical thickness of 4-unit cell LaAlO3 on SrTiO3 substrate is accompanied with head-to-head ferroelectric-like polarizations across the interface due to strain-rejuvenated ferroelectric-like instabilities in the materials. The divergent depolarization fields of the head-to-head polarizations cast the interface into an electron reservoir, forming screening electron gas in SrTiO3 with LaAlO3 hosting complementary localized holes. The ferroelectric-like polarizations and electron-hole juxtaposition reveal the cooperative nature of metallic LaAlO3/SrTiO3.
The Whole Atmosphere Community Climate Model version 6 (WACCM6) is a major update of the whole atmosphere modeling capability in the Community Earth System Model (CESM), featuring enhanced physical, ...chemical and aerosol parameterizations. This work describes WACCM6 and some of the important features of the model. WACCM6 can reproduce many modes of variability and trends in the middle atmosphere, including the quasi‐biennial oscillation, stratospheric sudden warmings, and the evolution of Southern Hemisphere springtime ozone depletion over the twentieth century. WACCM6 can also reproduce the climate and temperature trends of the 20th century throughout the atmospheric column. The representation of the climate has improved in WACCM6, relative to WACCM4. In addition, there are improvements in high‐latitude climate variability at the surface and sea ice extent in WACCM6 over the lower top version of the model (CAM6) that comes from the extended vertical domain and expanded aerosol chemistry in WACCM6, highlighting the importance of the stratosphere and tropospheric chemistry for high‐latitude climate variability.
Plain Language Summary
This manuscript describes the Whole Atmosphere Community Climate Model Version 6 (WACCM6), a chemistry and climate model which extends up to 140 km in the upper atmosphere. WACCM6 reproduces many important features of the climate system, and the addition of detailed chemistry and the higher than normal model top produces slightly improved simulations of the Arctic region.
Key Points
WACCM6 is a major upgrade to previous versions
WACCM6 can reproduce many modes of variability and trends in the middle atmosphere
WACCM6 provides improvements in high‐latitude climate variability at the surface and sea ice extent over a low top model
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