Major Block Research Articles

Insights Into Exhumation and Mantle Hydration Processes at the Deep Galicia Margin From a 3D High‐Resolution Seismic Velocity Model

AbstractHigh‐resolution velocity models developed using full‐waveform inversion (FWI) can image fine details of the nature and structure of the subsurface. Using a 3D FWI velocity model of hyper‐thinned crust at the Deep Galicia Margin (DGM) west of Iberia, we constrain the nature of the crust at this margin by comparing its velocity structure with those in other similar tectonic settings. Velocities representative of both the upper and lower continental crust are present, but there is no clear evidence for distinct upper and lower crustal layers within the hyper‐thinned crust. Our velocity model supports exhumation of the lower crust under the footwalls of fault blocks to accommodate the extension. We used our model to generate a serpentinization map for the uppermost mantle at the DGM, at a depth of 100 ms (∼340 m) below the S‐reflector, a low‐angle detachment that marks the base of the crust at this margin. We find a good alignment between serpentinized areas and the overlying major block bounding faults on our map, suggesting that those faults played an important role in transporting water to the upper mantle. Further, we observe a weak correlation between fault heaves and serpentinization beneath the hanging‐wall blocks, indicating that serpentinization was controlled by complex faulting during rifting. A good match between topographic highs of the S and local highly serpentinized areas of the mantle suggests that the morphology of the S was affected by the volume‐increasing process of serpentinization and deformation of the overlying crust.

Methanol—A Poor Biosignature Gas in Exoplanet Atmospheres

Biosignature gas research has been growing in recent years thanks to next-generation space- and ground-based telescopes. Methanol (CH3OH) has many advantages as a biosignature gas candidate. First, CH3OH’s hydroxyl group (OH) has a unique spectral feature not present in other anticipated gases in the atmospheres of rocky exoplanets. Second, there are no significant known abiotic CH3OH sources on terrestrial planets in the solar system. Third, life on Earth produces CH3OH in large quantities. However, despite CH3OH’s advantages, we consider it a poor biosignature gas in the atmospheres of terrestrial exoplanets due to the enormous production flux required to reach its detection limit. CH3OH’s high water solubility makes it very difficult to accumulate in the atmosphere. For the highly favorable planetary scenario of an exoplanet with an H2-dominated atmosphere orbiting an M5V dwarf star, we find that only when the column-averaged mixing ratio of CH3OH reaches at least 10 ppm can we detect it with the James Webb Space Telescope (JWST). The CH3OH bioproduction flux required to reach the JWST detection threshold of 10 ppm must be of the order of 1014 molecules cm−2 s−1, which is roughly three times the annual O2 production on Earth. Considering that such an enormous flux of CH3OH is essentially a massive waste of organic carbon—a major building block of life, we think this flux, while mathematically possible, is likely biologically unattainable. Although CH3OH can theoretically accumulate on exoplanets with CO2- or N2-dominated atmospheres, such planets’ small atmospheric scale heights and weak atmospheric signals put them out of reach for near-term observations.

Crustal and Upper Mantle Imaging of Botswana Using Magnetotelluric Method

We used magnetotelluric data from 352 sites in Botswana to derive a country-wide electrical conductivity model of the crust and upper mantle structure. A robust methodological scheme and 3D inversion were used to derive a 3D electrical conductivity model with unprecedented spatial coverage. The model results show interesting features, including the major cratonic blocks and the mobile belts in Botswana. A distinctive resistive structure was imaged in southwest Botswana, which suggests the existence of the Maltahohe microcraton as a separate cratonic unit as proposed by other studies. Furthermore, the model gives new insight into the extension of the East African Rift System to Botswana and the incipient rifting in the Okavango Rift Zone. In northern Botswana, the electrical conductivity model shows a highly conductive structure beneath the Okavango Rift Zone, which connects with a deeper conductive structure that we attribute to the East African Rift System due to its vicinity to Lake Kariba, the last surface expression of the rift system. We suggest that ascending fluids or melt from the East African Rift System causes the weakening of the lithosphere and plays a significant role in the incipient continental rifting in the Okavango Rift Zone.

Regulation of Inhibitory Signaling at the Receptor and Cellular Level; Advances in Our Understanding of GABAergic Neurotransmission and the Mechanisms by Which It Is Disrupted in Epilepsy.

Inhibitory signaling in the brain organizes the neural circuits that orchestrate how living creatures interact with the world around them and how they build representations of objects and ideas. Without tight control at multiple points of cellular engagement, the brain’s inhibitory systems would run down and the ability to extract meaningful information from excitatory events would be lost leaving behind a system vulnerable to seizures and to cognitive decline. In this review, we will cover many of the salient features that have emerged regarding the dynamic regulation of inhibitory signaling seen through the lens of cell biology with an emphasis on the major building blocks, the ligand-gated ion channel receptors that are the first transduction point when the neurotransmitter GABA is released into the synapse. Epilepsy association will be used to indicate importance of key proteins and their pathways to brain function and to introduce novel areas for therapeutic intervention.

Experimental study of quantum uncertainty from lack of information

Quantum uncertainty is a well-known property of quantum mechanics that states the impossibility of predicting measurement outcomes of multiple incompatible observables simultaneously. In contrast, the uncertainty in the classical domain comes from the lack of information about the exact state of the system. One may naturally ask, whether the quantum uncertainty is indeed a fully intrinsic property of the quantum theory, or whether similar to the classical domain lack of knowledge about specific parts of the physical system might be the source of this uncertainty. This question has been addressed in the previous literature where the authors argue that in the entropic formulation of the uncertainty principle that can be illustrated using the so-called, guessing games, indeed such lack of information has a significant contribution to the arising quantum uncertainty. Here we investigate this issue experimentally by implementing the corresponding two-dimensional and three-dimensional guessing games. Our results confirm that within the guessing-game framework, the quantum uncertainty to a large extent relies on the fact that quantum information determining the key properties of the game is stored in the degrees of freedom that remain inaccessible to the guessing party. Moreover, we offer an experimentally compact method to construct the high-dimensional Fourier gate which is a major building block for various tasks in quantum computation, quantum communication, and quantum metrology.

Ucp2 regulates neonatal cardiomyocytes proliferation through modulation of their mitochondrial metabolism

A major block to mammalian cardiac regeneration is the limited capacity of adult cardiomyocytes (CMs) to proliferate in response to injury. CMs proliferation is linked to oxidative metabolism: at birth, neonatal CMs endure a metabolic switch, with high reliance on fatty acid oxidation. This leads to increased mtROS production that has been shown to mediate their cell-cycle arrest. Thus, studying mitochondrial activity in the neonate is critical to understand constrains on CMs proliferation, regardless of their age. In this context, we focus of Ucp2, a mitochondrial carrier that plays a key role in regulation of cell fuel preferences and mtROS production. Our goal is to investigate whether Ucp2 can regulate neonatal CMs proliferation through modulation of their oxidative metabolism. Using inducible and complete Ucp2 KOs mice models together with RNAseq, flow cytometry and Seahorse analysis, we have addressed the role of Ucp2 in regulation of neonatal CMs proliferation, mtROS levels, mitochondrial biogenesis and metabolic activity. Being expressed at low levels during development, Ucp2 is upregulated from P1 to P7. Its expression then decreases to become barely detectable in the adult, thus correlating with CMs proliferative period. We show that neonatal Ucp2-/- CMs display a reduced mitochondrial respiration (OCR) that is not compensated by glycolysis. This low OCR is accompanied by a strong decrease in mitochondrial mass, together with alterations of ETC complexes expression, and to an increased reliance on glutaminolysis. In addition to decreased ATP/ADP ratio, we show that this impaired metabolic activity leads to reduction of CMs proliferation, a phenotype that is mediated by p38MAPK signaling pathway. We are currently assessing the consequences of loss of Ucp2 on neonatal heart metabolites levels and mitochondrial network. We hypothesize that Ucp2, through the export of metabolites from mitochondria to cytosol, takes part in mitochondrial retrograde signaling leading to regulation of CMs maturation and proliferation.

Reconsidering the Chemical Nature of Strand Breaks Derived from Abasic Sites in Cellular DNA: Evidence for 3'-Glutathionylation.

The hydrolytic loss of coding bases from cellular DNA is a common and unavoidable reaction. The resulting abasic sites can undergo β-elimination of the 3'-phosphoryl group to generate a strand break with an electrophilic α,β-unsaturated aldehyde residue on the 3'-terminus. The work reported here provides evidence that the thiol residue of the cellular tripeptide glutathione rapidly adds to the alkenal group on the 3'-terminus of an AP-derived strand break. The resulting glutathionylated adduct is the only major cleavage product observed when β-elimination occurs at an AP site in the presence of glutathione. Formation of the glutathionylated cleavage product is reversible, but in the presence of physiological concentrations of glutathione, the adduct persists for days. Biochemical experiments provided evidence that the 3'-phosphodiesterase activity of the enzyme apurinic/apyrimidinic endonuclease (APE1) can remove the glutathionylated sugar remnant from an AP-derived strand break to generate the 3'OH residue required for repair via base excision or single-strand break repair pathways. The results suggest that a previously unrecognized 3'glutathionylated sugar remnant─and not the canonical α,β-unsaturated aldehyde end group─may be the true strand cleavage product arising from β-elimination at an abasic site in cellular DNA. This work introduces the 3'glutathionylated cleavage product as the major blocking group that must be trimmed to enable repair of abasic site-derived strand breaks by the base excision repair or single-strand break repair pathways.

CNN based deep learning methods for precise analysis of cardiac arrhythmias

In contemporary day, Deep Learning (DL) is a developing discipline in the science of Machine Learning (ML) (ML). The research in this field is evolving extremely fast and its consequence leads to breakthrough in advance technology. Deep learning approaches are meant to gradually learn characteristics from several layers by adopting a general purpose learning mechanism, without relying on the human built features. This enables the system to learn the complicated functions and translate the input to the output straight from the data. This study effort primarily focuses on emphasising the Convolutional Neural Networks (CNNs), a kind of Deep Neural Networks (DNNs) and develop an 11 layered CNN for effective ECG arrhythmia classification. In this study the relevance of CNNs, the major building blocks and layers are explored, the design of the suggested CNN model is described.

Sometimes simple is not best: The complex γδ T cell interaction with tumour needs depth

Sometimes simple is not best: The complex γδ T cell interaction with tumour needs depth

Convergence in energy intensity of GDP: Evidence from West African countries

As convergence in energy-related series has implications for sustainable energy consumption, researchers in the field of energy economics are interested in investigating the stochastic nature of energy-related series, including the energy intensity of GDP. However, there is a limited focus on West Africa which is a major economic block within the African continent. This study thus contributes to the extant literature by investigating the convergence of energy intensity of GDP amongst the 15-member countries of the ECOWAS. Using time-series data from 1988 to 2019, the sigma, beta as well stochastic convergence tests were conducted. Overall, results show that the energy intensity of GDP converges for the majority of the West-African countries. In this regard, regionally coordinated energy policies will improve energy efficiency and promote sustainable energy consumption more than the national energy policy of individual West-African countries.

Trondhjemites from the Qianxi Complex, North China Craton: Implications for Neoarchean crustal growth

The TTG (tonalite‐trondhjemite‐granodiorite) rock suites are major building blocks of the Archean continental crust and their timing of formation and petrogenetic evolution are important keys to understanding the growth of continents in the Early Earth. Here we investigate trondhjemites from the Qiangxi Complex in the North China Craton and present petrological, geochemical and zircon U–Pb, REE and Lu–Hf data to understand the timing of their formation and petrogenetic history. The trondhjemites in our study belong to typical Archean Na‐rich TTG rocks and their geochemical features are similar to high‐Al TTG rocks. The geochemical characteristics of these rocks and the associated amphibolite indicate derivation from a subduction‐related hydrous basalt. The magmatic zircon grains from the trondhjemite samples show a peak 207Pb/206Pb age around 2,515 Ma. Magmatic zircon in the associated amphibolite also shows a similar age representing the timing of the protolith formation. Both the trondhjemites and amphibolite also contain metamorphic zircon grains which constrain the timing of metamorphism as 2,451–2,490 Ma, suggesting high‐grade metamorphism closely following the magmatism, associated with the assembly of the microblocks in the NCC. The geochemical characteristics and zircon age data presented in this study, in conjunction with those in previous studies from the Qiangxi Complex, suggest subduction‐related arc building occurred dominantly during 2.6–2.5 Ga. The Lu‐Hf isotope data from zircon grains in the trondhjemite and amphibolite samples of this study show dominantly positive εHf(t) values, indicating that the protolith magma was derived from juvenile components or depleted mantle. Our new results in conjunction with the data reported in earlier studies indicate a major crust‐building event through multiple magmatism during Neoarchean. The depleted mantle ages (TDM) of zircon in our samples range from 2,857 Ma to 2,605 Ma indicating that active subduction might have initiated in the late Mesoarchean, with the peak of magmatism during 2.6–2.5 Ga, followed by metamorphism at ca. 2.45–2.49 Ga.

Is Terzan 5 the remnant of a building block of the Galactic bulge? Evidence from APOGEE

ABSTRACT It has been proposed that the globular cluster-like system Terzan 5 is the surviving remnant of a primordial building block of the Milky Way bulge, mainly due to the age/metallicity spread and the distribution of its stars in the α–Fe plane. We employ Sloan Digital Sky Survey data from the Apache Point Observatory Galactic Evolution Experiment to test this hypothesis. Adopting a random sampling technique, we contrast the abundances of 10 elements in Terzan 5 stars with those of their bulge field counterparts with comparable atmospheric parameters, finding that they differ at statistically significant levels. Abundances between the two groups differ by more than 1σ in Ca, Mn, C, O, and Al, and more than 2σ in Si and Mg. Terzan 5 stars have lower [α/Fe] and higher [Mn/Fe] than their bulge counterparts. Given those differences, we conclude that Terzan 5 is not the remnant of a major building block of the bulge. We also estimate the stellar mass of the Terzan 5 progenitor based on predictions by the Evolution and Assembly of GaLaxies and their Environments suite of cosmological numerical simulations, concluding that it may have been as low as ∼3 × 108 M⊙ so that it was likely unable to significantly influence the mean chemistry of the bulge/inner disc, which is significantly more massive (∼1010 M⊙). We briefly discuss existing scenarios for the nature of Terzan 5 and propose an observational test that may help elucidate its origin.

Troxerutin-Mediated Complement Pathway Inhibition is a Disease-Modifying Treatment for Inflammatory Arthritis.

Troxerutin (TXR) is a phytochemical reported to possess anti-inflammatory and hepatoprotective effects. In this study, we aimed to exploit the antiarthritic properties of TXR using an adjuvant-induced arthritic (AIA) rat model. AIA-induced rats showed the highest arthritis score at the disease onset and by oral administration of TXR (50, 100, and 200 mg/kg body weight), reduced to basal level in a dose-dependent manner. Isobaric tags for relative and absolute quantitative (iTRAQ) proteomics tool were employed to identify deregulated joint homogenate proteins in AIA and TXR-treated rats to decipher the probable mechanism of TXR action in arthritis. iTRAQ analysis identified a set of 434 proteins with 65 deregulated proteins (log2 case/control≥1.5) in AIA. Expressions of a set of important proteins (AAT, T-kininogen, vimentin, desmin, and nucleophosmin) that could classify AIA from the healthy ones were validated using Western blot analysis. The Western blot data corroborated proteomics findings. In silico protein–protein interaction study of tissue-proteome revealed that complement component 9 (C9), the major building blocks of the membrane attack complex (MAC) responsible for sterile inflammation, get perturbed in AIA. Our dosimetry study suggests that a TXR dose of 200 mg/kg body weight for 15 days is sufficient to bring the arthritis score to basal levels in AIA rats. We have shown the importance of TXR as an antiarthritic agent in the AIA model and after additional investigation, its arthritic ameliorating properties could be exploited for clinical usability.

Austria’s Long-Term Care System: Challenges and Policy Responses

Approaches to design comprehensive support systems for people in need of long-term care (LTC) have appeared on the policy agenda of European countries from the 1990ies. Austria was one of the first to implement such a system separate from health care. In this last significant expansion of its social protection system, the country established a universal and tax-funded LTC system, departing from Austria’s Bismarckian tradition while carrying along the familialist logic and federalist structure in this policy field. Thirty years later, Austria now joins other countries in creating solutions to important contemporary challenges by discussing another major revamp of its LTC system. This paper renders a country case study to explain the development of Austrian LTC policies in greater depth and from a dynamic perspective. The two-step approach, starts with presenting the logics and major building blocks of Austria’s LTC system, and provides an update on its benefits and services. The second part identifies and discusses a raft of current and planned measures for three areas that appear critical in terms of future proofing LTC: (i) responses to staffing challenges, (ii) policy pilots to support informal carers, and finally, (iii) the role of digital transformation for LTC in Austria. This showcase exercise fosters policy learning and thus supports innovation and refinement of LTC systems. It could also serve as a futile starting point for comparative LTC policy research that moves beyond the outer hull of care-regime typologies to explore more specific system features and policy interventions.

Control of Dendritic Cell Function Within the Tumour Microenvironment.

The tumour microenvironment (TME) presents a major block to anti-tumour immune responses and to effective cancer immunotherapy. The inflammatory mediators such as cytokines, chemokines, growth factors and prostaglandins generated in the TME alter the phenotype and function of dendritic cells (DCs) that are critical for a successful adaptive immune response against the growing tumour. In this mini review we discuss how tumour cells and the surrounding stroma modulate DC maturation and trafficking to impact T cell function. Fibroblastic stroma and the associated extracellular matrix around tumours can also provide physical restrictions to infiltrating DCs and other leukocytes. We discuss interactions between the inflammatory TME and infiltrating immune cell function, exploring how the inflammatory TME affects generation of T cell-driven anti-tumour immunity. We discuss the open question of the relative importance of antigen-presentation site; locally within the TME versus tumour-draining lymph nodes. Addressing these questions will potentially increase immune surveillance and enhance anti-tumour immunity.

How to Build a Scalable Quantum Controller

We discuss quantum computers from the perspective of one of their major building blocks, the hardware controller, explaining how it fits into the computer and the requirements and challenges it poses for engineers and scientists.

Robust Through-Fin Avalanche in Vertical GaN Fin-JFET With Soft Failure Mode

We study the inherent ruggedness of the avalanche through the fin channel, a new avalanche mode in a vertical GaN power Fin-JFET, through single-pulse and repetitive avalanche circuit tests. By turning on the gate during avalanche, the major avalanche current path migrates from the p-GaN gate to the n-GaN fin channel. The single-pulse critical avalanche energy density ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {AVA}}$ </tex-math></inline-formula> ) was measured to be 10 J/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , which is the highest reported in GaN transistors. The Fin-JFET withstood over 3700 repetitive avalanche pulses at 70% of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {AVA}}$ </tex-math></inline-formula> . It exhibits a failure-to-open-circuit signature in single and repetitive avalanche. This soft failure mode allows the device to retain its full breakdown voltage, which is highly desirable for system robustness. By contrast, the through-gate avalanche in Fin-JFETs and the reported avalanche in Si and SiC transistors all show a destructive, failure-to-short-circuit signature. These results show the viability of soft avalanche failure in power devices, provide key robustness references for GaN devices, and suggest the fundamental superiority of moving the avalanche path away from the major blocking junction.

Quantum heat engines with Carnot efficiency at maximum power

Heat engines constitute the major building blocks of modern technologies. However, conventional heat engines with higher power yield lesser efficiency and vice versa and respect various power-efficiency trade-off relations. This is also assumed to be true for the engines operating in the quantum regime. Here we show that these relations are not fundamental. We introduce quantum heat engines that deliver maximum power with Carnot efficiency in the one-shot finite-size regime. These engines are composed of working systems with a finite number of quantum particles and are restricted to one-shot measurements. The engines operate in a one-step cycle by letting the working system simultaneously interact with hot and cold baths via semi-local thermal operations. By allowing quantum entanglement between its constituents and, thereby, a coherent transfer of heat from hot to cold baths, the engine implements the fastest possible reversible state transformation in each cycle, resulting in maximum power and Carnot efficiency. Finally, we propose a physically realizable engine using quantum optical systems.

Hyperextension and polyphase rifting: Impact on inversion tectonics and stratigraphic architecture of the North West Shelf, Australia

Restoration of interpreted 2D deep seismic lines across Australia's North West Shelf indicates that rifting style changed significantly during multiple phases of extension and continental breakup. Early phase rifting during the Neo-Proterozoic and Early Paleozoic, characterised by low-angle detachment faults, crustal-scale necking and hyperextension of the crust (Metamorphic Core Complex Mode), was localised over pre-existing Proterozoic orogenic belts formed adjacent to major cratonic blocks. Subsequent extensional events in the Late Paleozoic and Mesozoic reactivated these low-angle rift fault systems. However, a series of narrow rift basins (Narrow Rift Mode), bound by high-angle normal faults that cut into the upper mantle, also began forming due to changes in the rheological architecture of the lithosphere following previous extension, crustal thinning and post-rift cooling. Wide rift mode extension, wherein extensional deformation was distributed over broad areas, may have occurred prior to, or in conjunction with, the development of more localised narrow rifts (dual mode rifting) in areas such as the Northern Carnarvon and Browse basins. Extensional deformation progressively localised into the narrow rift basins, which in some cases, matured into seafloor spreading centres during breakup, typically outboard of the major low-angle detachment fault systems. The resulting general structural architecture evolution is consistent with several other hyperextended margins from around the world.The rift events were punctuated by periods of thermal sag, often in conjunction with pulses of compressional deformation associated with plate-scale tectonic events. Structural restoration of 2D regional seismic lines shows a marked difference in the way the different polyphase rift basin elements responded to shortening. Low-angle detachment faults were relatively well oriented for reactivation under compression, leading to the development of inversion anticlines and associated convergent unconformities towards the inboard basin margin. In contrast, high-angle normal fault systems associated with the pre-existing narrow rift basins were poorly oriented for reactivation during compression and tend to be characterised by minor wrench/flower structures, generally with relatively limited uplift and erosion on the basin margins. Regional in-plane compressional stresses also worked in combination with vertical loading due to thermal decay to downwarp the lithosphere, forming broad rapidly subsiding synclinal basins above axes of the pre-existing rift basins. The evolving structural architecture developed during the compressional events had significant impacts on the associated sequence stratigraphic architecture.

Eocene magmatism in the western Tengchong Block: Implications for crust-mantle interaction associated with the slab rollback of the Neo-Tethys Ocean

Granitoids are the major building blocks of Earth’s continental crust, and provide important insights into the evolution of continental crust and related mineral resources. Here we investigate the Eocene composite Lailishan pluton in the western Tengchong Block based on studies of petrology, mineral chemistry, zircon U-Pb-Hf isotopes, whole-rock geochemistry, and Sr-Nd isotope data to understand the petrogenesis and tectonic implications. The pluton is composed of monzogranite, syenogranite and abundant microgranitoid enclaves (ME) in the monzogranite. The zircon U-Pb data show similar rock formation ages in the range of 54–52 Ma. A diabase dyke intruded into the monzogranite at 54 Ma. The geochemical and isotopic signatures (εHf(t) of −11.6 to −3.1 and εNd(t) of −9.4 to −8.8) suggest that both the monzogranite and syenogranite were derived from the partial melting of metabasaltic rocks in the Mesoproterozoic Gaoligong metamorphic basement. The geochemical trends of the syenogranite indicate the significant fractional crystallization of biotite, plagioclase, K-feldspar, apatite, allanite and monazite, which further facilitated the enrichment of Sn in the syenogranite. The typical igneous textures, megacrysts from host granites, compositional zoning of the plagioclase and large variation of εHf(t) from −9.3 to −2.6 of the ME suggest a magma mixing and mingling process, which corresponds well with mass balance calculation using monzogranite and diabase as two endmembers. The mantle-like isotopic characteristics (εHf(t) of −2.4 to 2.0 and εNd(t) of −5.9) and low Th/La, Th/Nb and Nd/Pb ratios of the diabase dyke samples suggest the lithospheric mantle metasomatized by subducted fluids as the magma source. We propose that the slab rollback of the Neo-Tethys Ocean facilitated the interaction between crustal and mantle derived magmas generating a major pulse of Eocene magmatic activity in the Tengchong Block.