Background and purpose
Previous studies suggested that the overall burden of prior infections contributes to cardiovascular diseases and stroke. In the present study, the association between ...infectious burden (IB) and Alzheimer's disease (AD) was examined.
Methods
Antibody titers to common infectious pathogens including cytomegalovirus (CMV), herpes simplex virus type 1 (HSV‐1), Borrelia burgdorferi, Chlamydophila pneumoniae and Helicobacter pylori were measured by enzyme‐linked immunosorbent assay in 128 AD patients and 135 healthy controls. IB was defined as a composite serological measure of exposure to these common pathogens.
Results
Seropositivities toward zero−two, three and four−five of these pathogens were found in 44%, 40% and 16% of healthy controls but in 20%, 44% and 36% of AD patients, respectively. IB, bacterial burden and viral burden were independently associated with AD after adjusting for age, gender, education, APOE genotype and various comorbidities. Mini‐Mental State Examination scores were negatively correlated with IB in all cases. Serum beta‐amyloid protein (Aβ) levels (i.e. Aβ40, Aβ42 and total Aβ) and inflammatory cytokines (i.e. interferon‐γ, tumor necrosis factor α, interleukin‐1β and interleukin‐6) in individuals exposed to four−five infectious pathogens were significantly higher than those exposed to zero−two or three pathogens.
Conclusions
IB consisting of CMV, HSV‐1, B. burgdorferi, C. pneumoniae and H. pylori is associated with AD. This study supports the role of infection/inflammation in the etiopathogenesis of AD.
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The Earth's thermosphere and ionosphere (TI) are characterized by perpetual variability as integral parts of the atmosphere system, with intermittent disturbances from solar and geomagnetic forcing. ...This review examines how the TI variability is affected by processes originating from the lower atmosphere and implications for quantifying and forecasting the TI. This aspect of the TI variability has been increasingly appreciated in recent years from both observational and numerical studies, especially during the last extended solar minimum. This review focuses on the role of atmospheric waves, including tides, planetary waves, gravity waves, and acoustic waves, which become increasingly significant as they propagate from their source region to the upper atmosphere. Recent studies have led to better understanding of how these waves directly or indirectly affect TI wind, temperature, and compositional structures; the circulation pattern; neutral and ion species transport; and ionospheric wind dynamo. The variability of these waves on daily to interannual scales has been found to significantly impact the TI variability. Several outstanding questions and challenges have been highlighted: (i) large, seemingly stochastic, day‐to‐day variability of tides in the TI; (ii) control of model error in the TI region by the lower atmosphere; and (iii) the increasing importance of processes with shorter spatial and temporal scales at higher altitudes. Addressing these challenges requires model capabilities to assimilate observations of both lower and upper atmosphere and higher model resolution to capture complex interactions among processes over a broad range of scales and extended altitudes.
Key Points
Review the role of waves from lower atmosphere in thermosphere/ionosphere (TI) variability
Elucidate how predictability of the TI is affected by the lower atmosphere
Highlight outstanding questions in studying lower/upper atmosphere coupling
The amyloid-β protein (Aβ) protein plays a pivotal role in the pathogenesis of Alzheimer's disease (AD). It is believed that Aβ deposited in the brain originates from the brain tissue itself. ...However, Aβ is generated in both brain and peripheral tissues. Whether circulating Aβ contributes to brain AD-type pathologies remains largely unknown. In this study, using a model of parabiosis between APPswe/PS1dE9 transgenic AD mice and their wild-type littermates, we observed that the human Aβ originated from transgenic AD model mice entered the circulation and accumulated in the brains of wild-type mice, and formed cerebral amyloid angiopathy and Aβ plaques after a 12-month period of parabiosis. AD-type pathologies related to the Aβ accumulation including tau hyperphosphorylation, neurodegeneration, neuroinflammation and microhemorrhage were found in the brains of the parabiotic wild-type mice. More importantly, hippocampal CA1 long-term potentiation was markedly impaired in parabiotic wild-type mice. To the best of our knowledge, our study is the first to reveal that blood-derived Aβ can enter the brain, form the Aβ-related pathologies and induce functional deficits of neurons. Our study provides novel insight into AD pathogenesis and provides evidence that supports the development of therapies for AD by targeting Aβ metabolism in both the brain and the periphery.
Numerical simulations are performed for a sudden stratosphere warming (SSW) under different atmospheric tide and planetary wave forcing conditions to investigate the tidal variability in the ...mesosphere and lower thermosphere (MLT). The influence of variability of different tides in the MLT on generating perturbations to the low latitude ionosphere is also investigated. Significant changes are found to occur in the migrating semidiurnal solar (SW2) and lunar (M2) tides as well as in the westward propagating nonmigrating semidiurnal tide with zonal wave number 1 (SW1). The changes in the zonal mean atmosphere that occur during SSWs lead to an enhancement in the SW2 and M2 tides. The vertical wavelength of the SW2 is also changed, resulting in phase variability in the SW2 at a constant altitude. Significant enhancements in the SW1 are found to occur only in the presence of additional planetary wave forcing, and this demonstrates that nonlinear planetary wave‒tide interactions lead to the enhanced SW1 during SSWs. The amplitude and phase variability of the SW2 is found to be capable of producing temporal variability in the vertical plasma drift velocity that is similar to the observed variability. Changes in the M2 during SSWs can contribute up to an additional ∼30% of the total ionosphere variability; however, the overall influence of the lunar tide is found to be dependent upon the phase of the moon relative to the timing of the SSW. Although the influence is relatively minor, the SW1 also contributes to the low latitude ionosphere variability during SSWs. The simulation results for the vertical plasma drift velocity and total electron content (TEC) further illustrate that significant longitude variability occurs in the ionosphere response to SSWs.
Key Points
SW2, SW1, and M2 tides all contribute to ionosphere response to SSWs.
Lunar tide contributes ~30% of ionosphere response to SSWs.
Ionosphere response to SSW exhibits significant longitude dependence.
The coupling of the ionosphere to processes from below remains an elusive and difficult problem, as rapidly changing external drivers from above mask variations related to lower atmospheric sources. ...Here we use superposition of unique circumstances, current deep solar minimum and a record‐breaking stratospheric warming event, to gain new insights into causes of ionospheric perturbations. We show large (50–150%) persistent variations in the low‐latitude ionosphere (200–1000 km) that occur several days after a sudden warming event in the high‐latitude winter stratosphere (∼30 km). We rule out solar irradiance and geomagnetic activity as explanations of the observed variation. Using a general circulation model, we interpret these observations in terms of large changes in atmospheric tides from their nonlinear interaction with planetary waves that are strengthened during sudden warmings. We anticipate that further understanding of the coupling processes with planetary waves, accentuated during the stratospheric sudden warming events, has the potential of enabling the forecast of low‐latitude ionospheric weather up to several days in advance.
Large ionospheric variability is found at low to middle latitudes when a quasi‐stationary planetary wave is specified in the winter stratosphere in the National Center for Atmospheric Research ...thermosphere‐ionosphere‐mesosphere electrodynamics general circulation model for solar minimum conditions. The variability includes change of electric field/ion drift, F2 peak density and height, and the total electron content. The electric field/ion drift change is the largest near dawn in the numerical experiments. Analysis of model results suggests that, although the quasi‐stationary planetary wave does not propagate deep into the ionosphere or to low latitudes due to the presence of critical layers and strong molecular dissipation, the planetary wave and tidal interaction leads to large changes in tides, which can strongly impact the ionosphere at low and middle latitudes through the E region wind dynamo. Large zonal gradients of zonal and meridional winds from the tidal components and the zonal gradient of electric conductivities at dawn can produce large convergence/divergence of Hall and Pedersen currents, which in turn produces a polarization electric field. The ionospheric changes are dependent on both the longitude and local time, and are determined by the amplitudes and phases of the superposing wave components. The model results are consistent with observed ionospheric changes at low and middle latitudes during stratospheric sudden warming events, when quasi‐stationary planetary waves become large.
We report the first results of a global ionosphere/thermosphere simulation study that self‐consistently generates large‐scale equatorial spread F (ESF) plasma bubbles in the postsunset ionosphere. ...The coupled model comprises the ionospheric code SAMI3 and the atmosphere/thermosphere code WACCM‐X. Two cases are modeled for different seasons and geophysical conditions: the March case (low solar activity: F10.7 = 70) and the July case (high solar activity: F10.7 = 170). We find that equatorial plasma bubbles formed and penetrated into the topside F layer for the March case but not the July case. For the March case, a series of bubbles formed in the Atlantic sector with irregularity spacings in the range 400–1,200 km, rose to over 800 km, and persisted until after midnight. These results are consistent with recent GOLD observations. Calculation of the generalized Rayleigh‐Taylor instability (GRTI) growth rate shows that the e‐folding time was shorter for the March case than the July case.
Key Points
The first results from a high‐resolution, global simulation of equatorial spread F using realistic thermospheric conditions
The development of equatorial plasma bubbles is both longitudinally and seasonally dependent
Atmospheric waves play an essential role in “seeding” the generalized Rayleigh‐Taylor instability responsible for the instability
Thermoelectric properties of a black phosphorus/blue phosphorus van der Waals heterostructure are investigated by using first-principles calculations and Boltzmann transport theory for both electrons ...and phonons. It is found that the heterostructure is both energetically and kinetically stable even at higher temperature. Compared with those of the constituent black and blue phosphorus monolayers, the thermoelectric performance of the heterostructure is significantly enhanced due to sharply decreased thermal conductivity caused by the presence of van der Waals interactions, as well as obviously reduced band gaps and multi-valley structures resulting from type-II band alignment. As a consequence, the room temperature
ZT
value can reach 1.6, which is much higher than those of the components. Furthermore, we obtain
ZT
over 2.0 in a wide temperature range from 400 to 800 K, and a maximum
ZT
of ∼3.2 can be realized at 700 K, which is surprisingly good for systems consisting of light elements only.
Thermoelectric properties of a black phosphorus/blue phosphorus van der Waals heterostructure are investigated by using first-principles calculations and Boltzmann transport theory for both electrons and phonons.
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