The International Centre for Global Earth Models (ICGEM, http://icgem.gfz-potsdam.de/, last access: 6 May 2019) hosted at the GFZ German Research Centre for Geosciences (GFZ) is one of the five ...services coordinated by the International Gravity Field Service (IGFS) of the International Association of Geodesy (IAG). The goal of the ICGEM service is to provide the scientific community with a state-of-the-art archive of static and temporal global gravity field models of the Earth, and develop and operate interactive calculation and visualization services of gravity field functionals on user-defined grids or at a list of particular points via its website. ICGEM offers the largest collection of global gravity field models, including those from the 1960s to the 1990s, as well as the most recent ones, which have been developed using data from dedicated satellite gravity missions, CHAMP, GRACE, GOCE, advanced processing methodologies, and additional data sources such as satellite altimetry and terrestrial gravity. The global gravity field models have been collected from different institutions at international level and after a validation process made publicly available in a standardized format with DOI numbers assigned through GFZ Data Services. The development and maintenance of such a unique platform is crucial for the scientific community in geodesy, geophysics, oceanography, and climate research. In this article, we present the development history and future plans of ICGEM and its current products and essential services. We present the ICGEM's data by means of Earth's static, temporal, and topographic gravity field models as well as the gravity field models of other celestial bodies together with examples produced by the ICGEM's calculation and 3-D visualization services and give an insight into how the ICGEM service can additionally contribute to the needs of research and society.
The least-squares wavelet analysis, an alternative to the classical wavelet analysis, was introduced in order to analyze unequally spaced and non-stationary time series exhibiting components with ...variable amplitude and frequency over time. There are a few methods such as cross-wavelet transform and wavelet coherence that can analyze two time series together. However, these methods cannot generally be used to analyze unequally spaced and non-stationary time series with associated covariance matrices that may have trends and/or datum shifts. A new method of analyzing two time series together, namely the least-squares cross-wavelet analysis, is developed and applied to study the disturbances in the gravitational gradients observed by GOCE satellite that arise from plasma flow in the ionosphere represented by Poynting flux. The proposed method also shows its outstanding performance on the Westford–Wettzell very long baseline interferometry baseline length and temperature series.
With the launch of dedicated satellite gravity missions, starting with CHAllenging Minisatellite Payload (CHAMP) in 2000, with Gravity Recovery and Climate Experiment (GRACE) in 2002, and Gravity ...field and steady‐state Ocean Circulation Explorer (GOCE) in 2009, the accuracy and spatial resolution of the Earth's global gravity field models have been improved. Highly sensitive accelerometer measurements have not only been useful for gravity field modeling but have also been contributing to the studies of thermospheric dynamics. While improving the sensitivity of the accelerometer measurements, the new instrumentation used on board GOCE brings different challenges in understanding the data and developing sophisticated data processing. Our analyses reveal that the GOCE gravitational gradient measurements were affected by highly variable ionospheric dynamics that did not only degrade the quality of the GOCE Electrostatic Gravity Gradiometer (EGG) measurements but also proved that some characteristics of ionospheric dynamics can be measured by GOCE accelerometers and other Low Earth Orbiters. In this paper, we show how GOCE‐retrieved neutral winds respond to main ionospheric currents and we develop the impulse‐response relation between intense ionospheric dynamics (plasma drift) represented by Poynting energy flux and the gravity gradiometer tensor trace disturbances observed over the north geomagnetic polar region.
Plain Language Summary
The European Space Agency's (ESA) GOCE satellite gravity mission was launched in 2009 to study the Earth's gravitational field with the help of a gradiometer and a GPS receiver mounted onboard. The gradiometer consisted of six accelerometers in a special configuration that measured gravitational and nongravitational accelerations in space. The quality of the GOCE accelerometer measurements was degraded over the Earth's polar regions during periods of increased solar activity that caused uncommon dynamics in the space environment, known as magnetic storms. This finding did not only require to reinvestigate the GOCE data processing but has also compelled scientists to use GOCE accelerometer measurements, in an inverse mode, to understand the Earth's upper atmosphere dynamics. In our recent contribution, we showed for the first time that there exists a direct relationship between GOCE gradient disturbances and magnetic storms over the Earth's polar regions. This contribution takes our previous findings a step further by developing a mathematical model that reduces the GOCE gradient disturbances up to 30% over North America and Greenland, using electromagnetic energy flow derived from terrestrial magnetic disturbance measurements. Our contribution paves the way for a combination of gravity and ESA's Swarm mission to study and understand the Earth's upper atmosphere physics.
Key Points
Equivalent ionospheric currents and GOCE‐retrieved neutral winds in east‐west direction are remarkably coherent
GOCE measurement errors are modeled using external data that are markers of ionospheric dynamics
Low Earth orbiter accelerometer measurements can be extensively used to investigate specific features over specific areas in space physics
During the last few years, the determination of high-resolution global gravity field has gained momentum due to high-accuracy satellite-derived observations and development of forward gravity ...modelling. Forward modelling computes the global gravitational field from mass distribution sources instead of actual gravity measurements and helps improving and complementing the medium to high-frequency components of the global gravity field models. In this study, we approximate the global gravity potential of the Earth’s upper crust based on ellipsoidal approximation and a mass layer concept. Such an approach has an advantage of spectral methods and also avoids possible instabilities due to the use of a sequence of thin ellipsoidal shells. Lateral density within these volumetric shells bounded by confocal lower and upper shell ellipsoids is used in the computation of the ellipsoidal harmonic coefficients which are then transformed into spherical harmonic coefficients on the Earth’s surface in the final step. The main outcome of this research is a spectral representation of the gravitatioal potential of the Earth’s upper crust, computed up to degree and order 3660 in terms of spherical harmonic coefficients (ROLI_EllApprox_SphN_3660). We evaluate our methodology by comparing this model with other similar forward models in the literature which show sub-cm agreement in terms of geoid undulations. Finally, EIGEN-6C4 is augmented by ROLI_EllApprox_SphN_3660 and the gravity field functionals computed from the expanded model which has about 5 km half-wavelength spatial resolution are compared w.r.t. ground-truth data in different regions worldwide. Our investigations show that the contribution of the topographic model increases the agreement up to ~ 20% in the gravity value comparisons.
The present study was undertaken to investigate the individual and combined antioxidant or prooxidant effects of genistein, daidzein and quercetin in human erythrocytes and rat microsomes in vitro. ...Their reducing potential against oxidation of a redox sensitive fluorescent probe, their protective effect against H
2
O
2
-induced membrane lipid peroxidation and their inhibitory effect on AAPH-induced hemolysis were evaluated. Genistein and daidzein were prooxidant in erythrocytes but antioxidant in microsomes where their metabolites might have been formed which suggests the importance of metabolic capacity in in vitro models to predict the physiological situation. Quercetin showed antioxidant effects in all models and conditions. Prooxidant effect of 'genistein-daidzein mixture', at their concentrations reflecting the real life, was suppressed by addition of quercetin to the mixture. Our study shows that flavonoids can exert prooxidant effects depending on the conditions, but the mixture effect should be considered while assessing their effects and safety in humans.
Amelogenesis imperfecta (AI) is a collection of genetic disorders affecting the quality and/or quantity of tooth enamel. More than 20 genes are, so far, known to be responsible for this condition. In ...this study, we recruited 3 Turkish families with hypomaturation AI. Whole-exome sequence analyses identified disease-causing mutations in each proband, and these mutations cosegregated with the AI phenotype in all recruited members of each family. The AI-causing mutations in family 1 were a novel AMELX mutation NM_182680.1:c.143T>C, p.(Leu48Ser) in the proband and a novel homozygous MMP20 mutation NM_004771.3:c.616G>A, p.(Asp206Asn) in the mother of the proband. Previously reported compound heterozygous MMP20 mutations NM_004771.3:c.103A>C, p.(Arg35=) and c.389C>T, p.(Thr130Ile) caused the AI in family 2 and family 3. Minigene splicing analyses revealed that the AMELX missense mutation increased exonic definition of exon 4 and the MMP20 synonymous mutation decreased exonic definition of exon 1. These mutations would trigger an alteration of exon usage during RNA splicing, causing the enamel malformations. These results broaden our understanding of molecular genetic pathology of tooth enamel formation.
We examine the presence of residual nongravitational signatures in gravitational gradients measured by GOCE electrostatic gravity gradiometer. These signatures are observed over the magnetic poles ...during geomagnetically active days and can contaminate the trace of the gravitational gradient tensor by up to three to five times the expected noise level of the instrument (
∼
11 mE). We investigate these anomalies in the gradiometer measurements along many satellite tracks and examine possible causes using external datasets, such as interplanetary electric field measurements from the ACE (advanced composition explorer) and WIND spacecraft, and Poynting vector (flux) estimated from equivalent ionospheric currents derived from spherical elementary current systems over North America and Greenland. We show that the variations in the east-west and vertical electrical currents and Poynting vector components at the satellite position are highly correlated with the disturbances observed in the gradiometer measurements. The results presented in this paper reveal that the disturbances are due to intense ionospheric current variations that are enhanced by increased solar activity that causes a very dynamic drag environment. Moreover, successful modelling and removal of a high percentage of these disturbances are possible using external geomagnetic field observations.
Future liability considerations and stringent regulatory requirements often lead the users to choose end product-driven processes. Over the last decade, high-rate novel reactors have emerged for ...wastewater treatment, ensuring high removal efficiencies. An example is jet loop reactors offering a number of advantages that could be even further improved by attaining thermophilic conditions. In this study, a respirometric analysis was employed in a thermophilic jet loop reactor for treating potato-processing wastewater in order to determine the kinetic and stoichiometric parameters. The kinetic parameters namely maximum specific growth rate (μ
max
), yield ratio (Y), decay coefficient (k
d
), and half saturation rate constant (K
s
) were found to be 0.2 L/h, 0.71 g/g, 0.02 L/h, and 25.72 mg/L, respectively.
Bacillus mojavensis
,
Gordonia paraffinivorans
,
Bacillus badius
and
Paenibacillus lactis
strains were isolated from the thermophilic jet loop bioreactor. Considering the results, it is recommended that the estimation of kinetic and stoichiometric parameters in this system should preferentially be performed using respirometric techniques.
A highly transmissible severe acute respiratory coronavirus 2 (SARS‐CoV‐2) caused the coronavirus diseases 2019 (COVID‐19) pandemic, which resulted the highest morbidity and mortality rates among ...SARS‐CoV and MERS‐CoV. SARS‐CoV‐2 B.1.1.7 variant indicated the higher transmission among human‐to‐human and increasing hospitalisation. SARS‐CoV‐2 infection was observed in domestic animals showing human‐to‐pet transmission. In the current study, we report the first direct known human‐to‐cat transmission of the SARS‐CoV‐2 B.1.1.7 variant within the same family. Previous findings showed that companion animals can get infected by COVID‐19 patients after 3–6 weeks; however, according to our molecular findings, the cat was infected by the viral variant at the same period. Moreover, B.1.1.7 infection caused and developed several clinical symptoms including cardiac and ocular abnormalities. Overall, our findings determined the first direct and high transmission ability of the B.1.1.7 variant from COVID‐19 affected family members to cat. This result showed that the SARS‐CoV‐2 B.1.1.7 variant could have the highest transition capacity from human to domestic cat as shown for human‐to‐human. The governmental or worldwide policies should consider more detailed against the war with COVID‐19 pandemic.
This study investigates experimentally the flow structure between two identical square cylinders as well as in the wake of downstream cylinder that are in-line positioned in tandem. The experiments ...are performed in a large scale water channel under shallow water conditions. Time-averaged streamline pattern as well as vorticity and turbulence statistics were calculated using Particle Image Velocimetry (PIV) measurement method for different gap ratios (G/D=0.5 to G/D=5, where G is the distance between the cylinders and D is the diameter of cylinder) between the cylinders at a fixed Reynolds number of 4470. The measurements were conducted for both side view and plan view configurations at Froude number Fr = 0.186. The results obtained under shallow water conditions are compared with those obtained under deep water conditions by other researchers and it is found that, as explained in detail in the manuscript, the flow structures are remarkably different especially in the region between the two rectangular cylinders.
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