248 research outputs found
Sensitivity of Mountain Wave Drag Estimates on Separation Methods and Proposed Improvements
Internal gravity waves (GWs) are ubiquitous in the atmosphere, making significant contributions to the mesoscale motions. Since the majority of their spectrum is unresolved in global circulation models, their effects need to be parameterized. In recent decades GWs have been increasingly studied in high-resolution simulations, which, unlike direct observations, allow us to explore full spatio-temporal variations of the resolved wave field. In our study we analyze and refine a traditional method for GW analysis in a high-resolution simulation on a regional domain around the Drake Passage. We show that GW momentum drag estimates based on the Gaussian high-pass filter method applied to separate GW perturbations from the background are sensitive to the choice of a cutoff parameter. The impact of the cutoff parameter is higher for horizontal fluxes of horizontal momentum, which indicates higher sensitivity for horizontally propagating waves. Two modified methods, which choose the parameter value from spectral information, are proposed. The dynamically determined cutoff is mostly higher than the traditional cutoff values around 500 km, leading to larger GW fluxes and drag, and varies with time and altitude. The differences between the traditional and the modified methods are especially pronounced during events with significant drag contributions from horizontal momentum fluxes
Magnetohydrodynamic Enhanced Entry System for Space Transportation (MEESST) as a Key Building Block for Future Exploration Missions
Aside from the launch environment, atmospheric re-entry imposes one of the most demanding environments which a
spacecraft can experience. The combination of high spacecraft velocity and the presence of atmospheric particles leads
to partially ionised gas forming around the vehicle, which significantly inhibits radio communications, and leads to the
generation of high thermal loads on the spacecraft surface. Currently, the latter is solved using expensive, heavy, and
often expendable thermal protection systems (TPS). The use of electromagnetic fields to exploit Magnetohydrodynamic
(MHD) principles has long been considered as an attractive solution for this problem. By displacing the ionised gas away
from the spacecraft, the thermal loads can be reduced, while also opening a magnetic window for radio waves, mitigating
the blackout phenomenon. The application of this concept has to date not been possible due to the large magnetic fields
required, which would necessitate the use of exceptionally massive and power-hungry copper coils. High Temperature
Superconductors (HTS) have now reached industrial maturity. HTS coils can now offer the necessary low weight and
compactness required for space applications. The MEESST consortium the has been awarded a grant from the EU Horizon
2020 programme for the development and demonstration of a novel HTS-based re-entry system based with its foundation
on MHD principles. The project will first harmonize existing numerical codes, and then design, manufacture, and test a HTS
magnet. The study shows that the use of MEESST technology can have a positive impact on the cost-effectiveness and
available payload of interplanetary missions
Measurement of erythrocyte membrane mannoses to assess splenic function
ACKNOWLEDGEMENTS This work was funded by Aberdeen University Development Trust and Friends of Anchor. The University of Aberdeen is applying for a patent based on this work. Aberdeen University Development Trust (GrantNumber(s): DB10452-11) Friends of Anchor (GrantNumber(s): RS 2018 001)Peer reviewedPublisher PD
Observed and Modeled Mountain Waves from the Surface to the Mesosphere Near the Drake Passage
Four state-of-the-science numerical weather prediction (NWP) models were used to perform mountain wave- (MW) resolving hind-casts over the Drake Passage of a 10-day period in 2010 with numerous observed MW cases. The Integrated Forecast System (IFS) and the Icosahedral Nonhydrostatic (ICON) model were run at Δx ≈ 9 and 13 km globally. TheWeather Research and Forecasting (WRF) model and the Met Office Unified Model (UM) were both configured with a Δx = 3 km regional domain. All domains had tops near 1 Pa (z ≈ 80 km). These deep domains allowed quantitative validation against Atmospheric InfraRed Sounder (AIRS) observations, accounting for observation time, viewing geometry, and radiative transfer.
All models reproduced observed middle-atmosphere MWs with remarkable skill. Increased horizontal resolution improved validations. Still, all models underrepresented observed MW amplitudes, even after accounting for model effective resolution and instrument noise, suggesting even at Δx ≈ 3 km resolution, small-scale MWs are under-resolved and/or over-diffused. MWdrag parameterizations are still necessary in NWP models at current operational resolutions of Δx ≈ 10 km. Upper GW sponge layers in the operationally configured models significantly, artificially reduced MW amplitudes in the upper stratosphere and mesosphere. In the IFS, parameterized GW drags partly compensated this deficiency, but still, total drags were ≈ 6 time smaller than that resolved at Δx ≈ 3 km. Meridionally propagating MWs significantly enhance zonal drag over the Drake Passage. Interestingly, drag associated with meridional fluxes of zonal momentum (i.e. u'v') were important; not accounting for these terms results in a drag in the wrong direction at and below the polar night jet
Protein phosphorylation and its role in archaeal signal transduction
Reversible protein phosphorylation is the main mechanism of signal transduction that enables cells to rapidly respond to
environmental changes by controlling the functional properties of proteins in response to external stimuli. However,
whereas signal transduction is well studied in Eukaryotes and Bacteria, the knowledge in Archaea is still rather scarce.
Archaea are special with regard to protein phosphorylation, due to the fact that the two best studied phyla, the
Euryarchaeota and Crenarchaeaota, seem to exhibit fundamental differences in regulatory systems. Euryarchaeota (e.g.
halophiles, methanogens, thermophiles), like Bacteria and Eukaryotes, rely on bacterial-type two-component signal
transduction systems (phosphorylation on His and Asp), as well as on the protein phosphorylation on Ser, Thr and Tyr by
Hanks-type protein kinases. Instead, Crenarchaeota (e.g. acidophiles and (hyper)thermophiles) only depend on Hanks-type
protein phosphorylation. In this review, the current knowledge of reversible protein phosphorylation in Archaea is
presented. It combines results from identified phosphoproteins, biochemical characterization of protein kinases and
protein phosphatases as well as target enzymes and first insights into archaeal signal transduction by biochemical, genetic and polyomic studie
Longer telomere length in peripheral white blood cells is associated with risk of lung cancer and the rs2736100 (CLPTM1L-TERT) polymorphism in a prospective cohort study among women in China.
A recent genome-wide association study of lung cancer among never-smoking females in Asia demonstrated that the rs2736100 polymorphism in the TERT-CLPTM1L locus on chromosome 5p15.33 was strongly and significantly associated with risk of adenocarcinoma of the lung. The telomerase gene TERT is a reverse transcriptase that is critical for telomere replication and stabilization by controlling telomere length. We previously found that longer telomere length measured in peripheral white blood cell DNA was associated with increased risk of lung cancer in a prospective cohort study of smoking males in Finland. To follow up on this finding, we carried out a nested case-control study of 215 female lung cancer cases and 215 female controls, 94% of whom were never-smokers, in the prospective Shanghai Women's Health Study cohort. There was a dose-response relationship between tertiles of telomere length and risk of lung cancer (odds ratio (OR), 95% confidence interval [CI]: 1.0, 1.4 [0.8-2.5], and 2.2 [1.2-4.0], respectively; P trend = 0.003). Further, the association was unchanged by the length of time from blood collection to case diagnosis. In addition, the rs2736100 G allele, which we previously have shown to be associated with risk of lung cancer in this cohort, was significantly associated with longer telomere length in these same study subjects (P trend = 0.030). Our findings suggest that individuals with longer telomere length in peripheral white blood cells may have an increased risk of lung cancer, but require replication in additional prospective cohorts and populations
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ENIGMA and global neuroscience: A decade of large-scale studies of the brain in health and disease across more than 40 countries.
This review summarizes the last decade of work by the ENIGMA (Enhancing NeuroImaging Genetics through Meta Analysis) Consortium, a global alliance of over 1400 scientists across 43 countries, studying the human brain in health and disease. Building on large-scale genetic studies that discovered the first robustly replicated genetic loci associated with brain metrics, ENIGMA has diversified into over 50 working groups (WGs), pooling worldwide data and expertise to answer fundamental questions in neuroscience, psychiatry, neurology, and genetics. Most ENIGMA WGs focus on specific psychiatric and neurological conditions, other WGs study normal variation due to sex and gender differences, or development and aging; still other WGs develop methodological pipelines and tools to facilitate harmonized analyses of "big data" (i.e., genetic and epigenetic data, multimodal MRI, and electroencephalography data). These international efforts have yielded the largest neuroimaging studies to date in schizophrenia, bipolar disorder, major depressive disorder, post-traumatic stress disorder, substance use disorders, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorders, epilepsy, and 22q11.2 deletion syndrome. More recent ENIGMA WGs have formed to study anxiety disorders, suicidal thoughts and behavior, sleep and insomnia, eating disorders, irritability, brain injury, antisocial personality and conduct disorder, and dissociative identity disorder. Here, we summarize the first decade of ENIGMA's activities and ongoing projects, and describe the successes and challenges encountered along the way. We highlight the advantages of collaborative large-scale coordinated data analyses for testing reproducibility and robustness of findings, offering the opportunity to identify brain systems involved in clinical syndromes across diverse samples and associated genetic, environmental, demographic, cognitive, and psychosocial factors
A 16-Channel Receive, Forced Current Excitation Dual-Transmit Coil for Breast Imaging at 7T
To enable high spatial and temporal breast imaging resolution via combined use of high field MRI, array coils, and forced current excitation (FCE) multi channel transmit.A unilateral 16-channel receive array insert was designed for use in a transmit volume coil optimized for quadrature operation with dual-transmit RF shimming at 7 T. Signal-to-noise ratio (SNR) maps, g-factor maps, and high spatial and temporal resolution in vivo images were acquired to demonstrate the utility of the coil architecture.The dual-transmit FCE coil provided homogeneous excitation and the array provided an increase in average SNR of 3.3 times (max 10.8, min 1.5) compared to the volume coil in transmit/receive mode. High resolution accelerated in vivo breast imaging demonstrated the ability to achieve isotropic spatial resolution of 0.5 mm within clinically relevant 90 s scan times, as well as the ability to perform 1.0 mm isotropic resolution imaging, 7 s per dynamics, with the use of bidirectional SENSE acceleration of up to R = 9.The FCE design of the transmit coil easily accommodates the addition of a sixteen channel array coil. The improved spatial and temporal resolution provided by the high-field array coil with FCE dual-channel transmit will ultimately be beneficial in lesion detection and characterization
A Magnetohydrodynamic enhanced entry system for space transportation: MEESST
This paper outlines the initial development of a novel magnetohydrodynamic (MHD) plasma control system which aims at mitigating shock-induced heating and the radio-frequency communication blackout typically encountered during (re-)entry into planetary atmospheres. An international consortium comprising universities, SMEs, research institutions, and industry has been formed in order to develop this technology within the MEESST project. The latter is funded by the Future and Emerging Technologies (FET) program of the European Commission’s Horizon 2020 scheme (grant no. 899298). Atmospheric entry imposes one of the harshest environments which a spacecraft can experience. The combination of hypersonic velocities and the rapid compression of atmospheric particles by the spacecraft leads to high-enthalpy, partially ionised gases forming around the vehicle. This inhibits radio communications and induces high thermal loads on the spacecraft surface. For the former problem, spacecraft can sometimes rely on satellite constellations for communicating through the plasma wake and therefore preventing the blackout. On the other hand, expensive, heavy, and non-reusable thermal protection systems (TPS) are needed to dissipate the severe thermal loads. Such TPS can represent up to 30% of an entry vehicles weight, and especially for manned missions they can reduce the cost- efficiency by sacrificing payload mass. Such systems are also prone to failure, putting the lives of astronauts at risk. The use of electromagnetic fields to exploit MHD principles has long been considered as an attractive solution for tackling the problems described above. By pushing the boundary layer of the ionized gas layer away from the spacecraft, the thermal loads can be reduced, while also opening a magnetic window for radio communications and mitigating the blackout phenomenon. The application of this MHD-enabled system has previously not been demonstrated in realistic conditions due to the required large magnetic fields (on the order of Tesla or more), which for conventional technologies would demand exceptionally heavy and power-hungry electromagnets. High-temperature superconductors (HTS) have reached a level of industrial maturity sufficient for them to act as a key enabling technology for this application. Thanks to superior current densities, HTS coils can offer the necessary low weight and compactness required for space applications, with the ability to generate the strong magnetic fields needed for entry purposes. This paper provides an overview of the MEESST project, including its goals, methodology and some preliminary design considerations
The Origin and Contribution of Cancer-Associated Fibroblasts in Colorectal Carcinogenesis
Background & Aims: Cancer-associated fibroblasts (CAFs) play an important role in colorectal cancer (CRC) progression and predict poor prognosis in CRC patients. However, the cellular origins of CAFs remain unknown, making it challenging to therapeutically target these cells. Here, we aimed to identify the origins and contribution of colorectal CAFs associated with poor prognosis. Methods: To elucidate CAF origins, we used a colitis-associated CRC mouse model in 5 different fate-mapping mouse lines with 5-bromodeoxyuridine dosing. RNA sequencing of fluorescence-activated cell sorting–purified CRC CAFs was performed to identify a potential therapeutic target in CAFs. To examine the prognostic significance of the stromal target, CRC patient RNA sequencing data and tissue microarray were used. CRC organoids were injected into the colons of knockout mice to assess the mechanism by which the stromal gene contributes to colorectal tumorigenesis. Results: Our lineage-tracing studies revealed that in CRC, many ACTA2+ CAFs emerge through proliferation from intestinal pericryptal leptin receptor (Lepr)+ cells. These Lepr-lineage CAFs, in turn, express melanoma cell adhesion molecule (MCAM), a CRC stroma-specific marker that we identified with the use of RNA sequencing. High MCAM expression induced by transforming growth factor β was inversely associated with patient survival in human CRC. In mice, stromal Mcam knockout attenuated orthotopically injected colorectal tumoroid growth and improved survival through decreased tumor-associated macrophage recruitment. Mechanistically, fibroblast MCAM interacted with interleukin-1 receptor 1 to augment nuclear factor κB–IL34/CCL8 signaling that promotes macrophage chemotaxis. Conclusions: In colorectal carcinogenesis, pericryptal Lepr-lineage cells proliferate to generate MCAM+ CAFs that shape the tumor-promoting immune microenvironment. Preventing the expansion/differentiation of Lepr-lineage CAFs or inhibiting MCAM activity could be effective therapeutic approaches for CRC
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