The Global Airglow (GLOW) model has been updated and extended to calculate thermospheric emissions in the far ultraviolet, including sources from daytime photoelectron‐driven processes, nighttime ...recombination radiation, and auroral excitation. It can be run using inputs from empirical models of the neutral atmosphere and ionosphere or from numerical general circulation models of the coupled ionosphere‐thermosphere system. It uses a solar flux module, photoelectron generation routine, and the Nagy‐Banks two‐stream electron transport algorithm to simultaneously handle energetic electron distributions from photon and auroral electron sources. It contains an ion‐neutral chemistry module that calculates excited and ionized species densities and the resulting airglow volume emission rates. This paper describes the inputs, algorithms, and code structure of the model and demonstrates example outputs for daytime and auroral cases. Simulations of far ultraviolet emissions by the atomic oxygen doublet at 135.6 nm and the molecular nitrogen Lyman‐Birge‐Hopfield bands, as viewed from geostationary orbit, are shown, and model calculations are compared to limb‐scan observations by the Global Ultraviolet Imager on the TIMED satellite. The GLOW model code is provided to the community through an open‐source academic research license.
Plain Language Summary
The Global Airglow (GLOW) model has been updated and extended to calculate ultraviolet light emitted by the upper atmosphere, including during the day, during the night, and in the aurora. It can be run using inputs from standard climatological models of the upper atmosphere and ionosphere or from complex computer models that describe the dynamics of the ionosphere. It computes energetic electron fluxes from both solar and auroral sources, and it contains a chemistry module that calculates the densities of excited and ionized atoms and molecules, and the resulting airglow emission rates. This paper describes the inputs, algorithms, and code structure of the model and demonstrates example outputs for daytime and the aurora. Simulations of ultraviolet emissions by atomic oxygen and molecular nitrogen, as viewed from geostationary orbit, are shown, and model calculations are compared to observations by the Global Ultraviolet Imager on the TIMED satellite. The GLOW model code is provided to the community through an open‐source academic research license.
Key Points
A new version of the open‐source Global Airglow (GLOW) model is released
New features include selected far ultraviolet emissions, interfaces to general circulation models, and parallel processing
Comparison with far ultraviolet limb scan measurements shows reasonable agreement
Mutations in PIK3CA, which encodes the p110α subunit of the insulin-activated phosphatidylinositol-3 kinase (PI3K), and loss of function mutations in PTEN, which encodes a phosphatase that degrades ...the phosphoinositide lipids generated by PI3K, are among the most frequent events in human cancers
. However, pharmacological inhibition of PI3K has resulted in variable clinical responses, raising the possibility of an inherent mechanism of resistance to treatment. As p110α mediates virtually all cellular responses to insulin, targeted inhibition of this enzyme disrupts glucose metabolism in multiple tissues. For example, blocking insulin signalling promotes glycogen breakdown in the liver and prevents glucose uptake in the skeletal muscle and adipose tissue, resulting in transient hyperglycaemia within a few hours of PI3K inhibition. The effect is usually transient because compensatory insulin release from the pancreas (insulin feedback) restores normal glucose homeostasis
. However, the hyperglycaemia may be exacerbated or prolonged in patients with any degree of insulin resistance and, in these cases, necessitates discontinuation of therapy
. We hypothesized that insulin feedback induced by PI3K inhibitors may reactivate the PI3K-mTOR signalling axis in tumours, thereby compromising treatment effectiveness
. Here we show, in several model tumours in mice, that systemic glucose-insulin feedback caused by targeted inhibition of this pathway is sufficient to activate PI3K signalling, even in the presence of PI3K inhibitors. This insulin feedback can be prevented using dietary or pharmaceutical approaches, which greatly enhance the efficacy/toxicity ratios of PI3K inhibitors. These findings have direct clinical implications for the multiple p110α inhibitors that are in clinical trials and provide a way to increase treatment efficacy for patients with many types of tumour.
In contrast to rigid body autonomous underwater vehicle (AUV) models, elastic AUV models will exhibit hydrodynamic effects due to elastic deformation of the shell during water entry, influencing ...their load-response characteristics. In this paper, the predictive capability of the selected simulation method is first verified by comparing the simulation results with test data acquired from experiments conducted in a drop-test tank. Then, the effects of the head shape parameters, shell thickness and water-entry state, such as the water-entry velocity and angle, on the acceleration, pressure, stress and structural deformation of an elastic AUV during water-entry impact are investigated. By comparing the characteristics of rigid and elastic bodies, the influence of the hydroelastic effect is revealed. The research results can provide guidance on the design of airborne vehicles and transmedia vehicles.
Biofilm formation in drinking water distribution systems (DWDS) is influenced by the source water, the supply infrastructure and the operation of the system. A holistic approach was used to advance ...knowledge on the development of mixed species biofilms in situ, by using biofilm sampling devices installed in chlorinated networks. Key physico-chemical parameters and conventional microbial indicators for drinking water quality were analysed. Biofilm coverage on pipes was evaluated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The microbial community structure, bacteria and fungi, of water and biofilms was assessed using pyrosequencing. Conventional wisdom leads to an expectation for less microbial diversity in groundwater supplied systems. However, the analysis of bulk water showed higher microbial diversity in groundwater site samples compared with the surface water site. Conversely, higher diversity and richness were detected in biofilms from the surface water site. The average biofilm coverage was similar among sites. Disinfection residual and other key variables were similar between the two sites, other than nitrates, alkalinity and the hydraulic conditions which were extremely low at the groundwater site. Thus, the unexpected result of an exceptionally low diversity with few dominant genera (Pseudomonas and Basidiobolus) in groundwater biofilm samples, despite the more diverse community in the bulk water, is attributed to the low-flow hydraulic conditions. This finding evidences that the local environmental conditions are shaping biofilm formation, composition and amount, and hence managing these is critical for the best operation of DWDS to safeguard water quality.
An empirical observation of a relationship between a striking feature of electronic transmission through a π-system, destructive quantum interference (QI), on one hand, and the stability of ...diradicals on the other, leads to the proof of a general theorem that relates the two. Subject to a number of simplifying assumptions, in a π-electron system, QI occurs when electrodes are attached to those positions of an N-carbon atom N-electron closed-shell hydrocarbon where the matrix elements of the Green’s function vanish. These zeros come in two types, which are called easy and hard. Suppose an N+2 atom, N+2 electron hydrocarbon is formed by substituting 2 CH₂ groups at two atoms, where the electrodes were. Then, if a QI feature is associated with electrode attachment to the two atoms of the original N atom system, the resulting augmented N+2 molecule will be a diradical. If there is no QI feature, i.e., transmission of current is normal if electrodes are attached to the two atoms, the resulting hydrocarbon will not be a diradical but will have a classical closed-shell electronic structure. Moreover, where a diradical exists, the easy zero is associated with a nondisjoint diradical, and the hard zero is associated with a disjoint one. A related theorem is proven for deletion of two sites from a hydrocarbon.
Biofilms are ubiquitous throughout drinking water distribution systems (DWDS), playing central roles in system performance and delivery of safe clean drinking water. However, little is known about ...how the interaction of abiotic and biotic factors influence the microbial communities of these biofilms in real systems. Results are presented here from a one-year study using in situ sampling devices installed in two operational systems supplied with different source waters. Independently of the characteristics of the incoming water and marked differences in hydraulic conditions between sites and over time, a core bacterial community was observed in all samples suggesting that internal factors (autogenic) are central in shaping biofilm formation and composition. From this it is apparent that future research and management strategies need to consider the specific microorganisms found to be able to colonise pipe surfaces and form biofilms, such that it might be possible to exclude these and hence protect the supply of safe clean drinking water.
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•Main abiotic factors affecting microbial distribution were flow, temperature and pH.•Internal factors were central in shaping biofilm formation and composition.•Ubiquitous core bacterial community observed in all biofilm samples.•The less abundant bacteria were responsible for most of the variability.•This information is essential for the management of drinking water systems.
The National Aeronautics and Space Administration Global‐scale Observations of the Limb and Disk ultraviolet spectrograph has been imaging the equatorial ionization anomaly (EIA), regions of the ...ionosphere with enhanced electron density north and south of the magnetic equator, since October 2018. The initial 3 months of observations was during solar minimum conditions, and they included observations in December solstice of unanticipated variability and depleted regions. Depletions are seen on most nights, in contrast to expectations from previous space‐based observations. The variety of scales and morphologies also pose challenges to understanding of the EIA. Abrupt changes in the EIA location, which could be related to in situ measurements of large‐scale depletion regions, are observed on some nights. Such synoptic‐scale disruptions have not been previously identified.
Plain Language Summary
In this study, ultraviolet images of emissions from the Earth's nighttime ionosphere were examined to determine the location of the equatorial ionization anomaly, regions of enhanced ionization that result in bands of nighttime airglow emission that typically appear parallel to the magnetic equator near +15° and −15° magnetic latitude. We found that gaps in the anomaly are observed much more frequently in these observations than in previous space‐based observations. These gaps, sometimes referred to as ionospheric bubbles or depletions, are important because they are associated with ionospheric changes that can cause disruptions in communications and satellite navigation that depend on satellites, such as GPS. The location of the anomaly was also observed to vary significantly, by as much as 15°, from the typical latitudes. The observed level of variability seen during the unusually quiet geomagnetic conditions during which the observations occurred suggests that accurate predictions of the location and variability of the equatorial ionization anomaly requires significant advances in understanding the causes of this variability.
Key Points
During geomagnetically quiet solar minimum conditions, significant temporal and spatial variability is observed in the equatorial ionosphere
At solar minimum, depleted ionospheric regions are observed on most nights, at varying longitudes, and with evident meridional symmetry
Synoptic‐scale disruptions of the ionization crests are seen on several nights, possibly associated with large‐scale plasma instabilities
Neutral density shows complicated temporal and spatial variations driven by external forcing of the thermosphere/ionosphere system, internal dynamics, and thermosphere and ionosphere coupling. ...Temporal variations include abrupt changes with a time scale of minutes to hours, diurnal variation, multi-day variation, solar-rotational variation, annual/semiannual variation, solar-cycle variation, and long-term trends with a time scale of decades. Spatial variations include latitudinal and longitudinal variations, as well as variation with altitude. Atmospheric drag on satellites varies strongly as a function of thermospheric mass density. Errors in estimating density cause orbit prediction error, and impact satellite operations including accurate catalog maintenance, collision avoidance for manned and unmanned space flight, and re-entry prediction. In this paper, we summarize and discuss these density variations, their magnitudes, and their forcing mechanisms, using neutral density data sets and modeling results. The neutral density data sets include neutral density observed by the accelerometers onboard the Challenging Mini-satellite Payload (CHAMP), neutral density at satellite perigees, and global-mean neutral density derived from thousands of orbiting objects. Modeling results are from the National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-electrodynamics general circulation model (TIE-GCM), and from the NRLMSISE-00 empirical model.
AbstractThis study examines the estimated tsunami loads on five California coastal bridges. The quantities of interest include the horizontal and vertical forces and overturning moment. The ...simulations and analysis are conducted for two stages: (1) initial impact and overtopping and (2) full inundation. The first stage starts from the time when the tsunami water free-surface elevation reaches the low chord of the bridge superstructure, the water free surface rises and reaches the top of the bridge barrier where it overtops the bridge and starts to flow on the bridge deck, and until the bridge is totally inundated. The second stage occurs when the bridge first becomes fully inundated, i.e., end of the first stage, and until the most critical events, (1) the maximum tsunami water velocity, (2) the maximum tsunami momentum flux, and (3) the maximum tsunami mass flux, have occurred. The first part of the initial impact and overtopping stage leads to a combination of lateral (horizontal) and uplift (upward vertical) forces. The maximum uplift force during Stage 1 is found to occur when the tsunami water free-surface elevation reaches the top of the bridge barrier right before the water overtops the bridge and starts to flow onto the bridge deck. It is observed that the time interval representing the initial impact of the tsunami on the bridge superstructure leads to the maximum horizontal force, downward vertical force, and overturning moment. The overall maximum uplift force is found to be in tsunami scenarios in which the bridge superstructure is totally inundated, i.e., in Stage 2, if total inundation actually occurs. Analyzing a deck-girder bridge with a failed, i.e., removed, first seaward girder shows a 15% reduction in the maximum horizontal force. The uplift force is found to be approximately 25% larger for the bridge with a failed first girder. A design procedure is proposed to compute the maximum horizontal and vertical forces on bridge superstructures based on the simulation results. Good agreement between numerical predictions and formula estimations of the tsunami forces is observed. The proposed design procedure is intended to provide estimations of tsunami loads on bridge superstructures.
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