Rapid Breakup Research Articles

Imaging the May 2024 Extreme Aurora With Ionospheric Total Electron Content

AbstractThe continental United States is well instrumented with facilities for mid‐latitude upper atmosphere research that operate on a continuous basis. In addition, citizen scientists provide a wealth of information when unusual events occur. We combine ionospheric total electron content (TEC) data from distributed arrays of GNSS receivers, magnetometer chains, and auroral observations obtained by citizen scientists, to provide a detailed view of the intense auroral breakup and westward surge occurring at the peak of the 10–11 May 2024 extreme geomagnetic storm. Over a 20‐min interval, vertical TEC (vTEC) increased at unusually low latitude (∼45°) and rapidly expanded azimuthally across the continent. Individual receiver/satellite data sets indicate sharp bursts of greatly elevated of vTEC (∼50 TECu). Intense red aurora was co‐located with the leading edge of the equatorward and westward TEC enhancements, indicating that the large TEC enhancement was created by extremely intense low‐energy precipitation during the rapid substorm breakup.

Azerbaijan’s offensive in Nagorno-Karabakh and the evolution of its dispute with Armenia

In September 2023, Azerbaijan launched a military offensive into Nagorno-Karabakh that led to the rapid capitulation and break-up of the territory’s governing authority.

Impact of COVID-19 on the Prevalence of Dry Eye Among Young Adults in Kuala Lumpur Malaysia

Introduction: Dry eye is a significant eye health issue. In dry eyes, the tear film is weakened, mostly due to low tear film quality and the quantity of secretion. This low quality of tear secretion can lead to the rapid breakup of tears. In recent times, particularly since the COVID-19 pandemic, the prevalence of dry eye has increased. Relevant studies found that the prevalence of dry eye is higher in females than males. This research work is based only on symptoms of dry eye disease in Malaysia to determine its prevalence among students at the UCSI University KL campus because of the increase in reported cases of dry eyes especially post Movement Control Order (MCO). Methods: A total of 199 students, ranging in age 17 to 30, were included in this research. This is a cross-sectional study that was conducted on participants who fulfilled the inclusion criteria. Demographic questionnaires and Ocular Surface Disease Index (OSDI) results were collected. Results: On the UCSI KL Campus, students who suffer from dry eye are 82% of the population. The Pearson Chi-Square test showed a significant difference between gender and dry eye, X2 (1, N= 199) = 8.64, p < 0.0033. Female students are more likely to develop dry eye than male students. Conclusion: The prevalence of dry eyes among UCSI students is high. This could be attributable to prolonged or improper mask-wearing. It is suggested that researchers and health policymakers should take heed to these emerging risk factors related to wearing of mask.

Regener-Eyes® Ophthalmic Solution: A New Therapeutic Agent to Relieve Dryness of the Eye for Tear Hyperosmolarity-Induced Pathological Changes in the Eyes of Patients Suffering From Dry Eye Discomfort

Tear hyperosmolarity is an initial and crucial step in the development, progression and aggravation of dry eye discomfort. Decreased tear secretion or altered tear composition leads to tear film instability/imbalance which in Dry Eye (DE) patients results in abnormally rapid breakup of the tear film after blinking. Numerous structural changes in epithelial cells and mucin-producing goblet cells develop as a consequence of exposition of these cells to the hyperosmolar tears. Tear hyperosmolarity causes oxidative stress, disruption of DNA repair system and induces DNA damage in the cells of ocular surface and lacrimal system, leading to their apoptosis. An injury of lacrimal glands results in decreased tear secretion, enabling the creation of “positive loop” that leads to the DE progression and aggravation. Accordingly, eye drops, which alleviate tear hyperosmolarity and restore tear homeostasis at corneal surface, will break up vicious DEcycle and will relieve eye pain, irritation, discomfort, and vision disturbance in DE patients. Regener-Eyes® Ophthalmic Solution is a hypotonic solution enriched with osmoprotectants (that address the hyperosmolarity of a tear film), which helps support tear stability and contribute to relieve dryness of the eye in DE patients. In this article, we summarized current knowledge and future perspectives about topical administration of Regener-Eyes® Ophthalmic Solution to relieve dryness of the eye in DE patients.

Surface Properties of N,N-Dimethylformamide-Water Mixtures, As Seen from Computer Simulations.

The liquid-vapor interface of N,N-dimethylformamide (DMF)-water mixtures, spanning the entire composition range, is investigated in detail at 298 K by molecular dynamics simulation and intrinsic surface analysis. DMF molecules are found to adsorb strongly at the liquid surface, but this adsorption extends only to the first molecular layer. Water and DMF molecules mix with each other on the molecular scale even in the surface layer; thus, no marked self-association of any of the components is seen at the liquid surface. The major surface component prefers such orientation in which the molecular dipole vector lays parallel with the macroscopic plane of the surface. On the other hand, the preferred orientation of the minor component is determined, at both ends of the composition range, by the possibility of H-bond formation with the major component. The lack of H-donating ability of DMF leads to a rapid breakup of the percolating H-bond network at the surface; due to the strong adsorption of DMF, this breakup occurs below the bulk phase DMF mole fraction of 0.03. The disruption of the surface H-bond network also accelerates the exchange of both species between the liquid surface and bulk liquid phase, although, for water, this effect becomes apparent only above a bulk phase DMF mole fraction of 0.4. H-bonds formed by a DMF and a water molecule live, on average, 25-60% longer than those formed by two water molecules at the liquid surface. A similar, but smaller (i.e., about 10-20%) difference is seen in the bulk liquid phase. The enhanced surface mobility of the molecules results in 2-6 times larger diffusion coefficient and 2-5 times shorter H-bond lifetime values at the liquid surface than in the bulk liquid phase. The diffusion of both molecules is slowed down in the presence of the other species; in the case of DMF, this effect is caused by the formation of water-DMF H-bonds, whereas for water, steric hindrances imposed by the bulky DMF neighbors are responsible for this slowing down.

Dense-field spray droplet size quantification of flashing boiling atomization using structured laser illumination planar imaging technique

The statistics of droplets formed by the primary jet breakup of a liquid atomization system are critical since it determines the atomization quality and resultant spray characteristics. However, quantifying the droplet statistics by applying optical diagnostic instruments is challenging because of the dense population of droplets near the nozzle exit. In a flash boiling spray, the more rapid breakup produces a higher optical dense droplet cloud, which is more challenging. Besides, the interference from the vapor phase heavily evaporated is more problematic. In this study, we incorporated an in-house developed laser-induced exciplex fluorescence (LIEF/Mie) based droplet sizing technique to quantify the near-field droplet characteristics of a single jet flash boiling spray, which can separate the liquid spray from the vapor phase to eliminate the influence of the vaporization. To mitigate the interference of multiple scattering in the dense region, a 3-phase structured laser illumination planar imaging (3p-SLIPI) facility was implemented into the measuring system to modulate the laser beam. The combination of these two unique techniques succeeded in obtaining accurate quantification of a planar droplet size distribution of this flash boiling spray. The 3p-SLIPI-LIEF/Mie measurements were validated against phase Doppler interferometry (PDI) droplet size measurement results. It is found from this study that the SLIPI-LIEF/Mie results are more accurate and more appropriate for simulation or theoretical analysis compared to LIEF/Mie results. The investigation of the flash boiling sprays under various superheat conditions was conducted using this technique. The quantitative near-field droplet size information reveals the prompt atomization mechanism of the flash boiling sprays. Comparing to the non-flash boiling sprays, the SMD is much smaller, the distribution is more uniform, and the tendency becomes more significant as the superheat degree increases. The SLIPI-LIEF/Mie results show that there is no liquid core region or sudden droplet size reduction due to flash boiling secondary micro-explosion breakups. Rather, a central dense region formed due to rapid expansion and evaporation at the exterior zones of the flash boiling spray was found.

Breakup Dynamics of Droplets in Symmetric Y-Junction Microchannels

The experimental method is used to study the droplet breaking characteristics of an immiscible liquid–liquid t8wo-phase fluid in symmetric Y-junction microchannels. Silicone oil is used as the dispersed phase and distilled water containing 0.5% SDS is used as the continuous phase. Three breakup behaviors were observed: breakup with permanent obstruction, breakup with gaps, and no breakup. Two stages of the change of the neck width of the sub-droplet during the breakup process were discovered: a rapid breakup stage and a thread breakup stage. The effect of the breakup behavior on the flow pattern was investigated and it was found that the breakup behavior of the droplets made the slug flow area smaller; further, a new flow pattern was observed, being droplet flow. The length of the sub-droplet increases with an increase of the volume flow rate of the dispersed phase and the ratio of the volume flow rate of the dispersed phase to the continuous phase, while decreasing with an increase of the volume flow rate and the capillary number of the continuous phase. Based on the influence of the two-phase flow parameters on the length of the sub-droplet, a correlation formula for the length of the sub-droplet with good predictive performance is proposed.

Numerical investigation of atomization of swirling liquid sheets using transforming algorithm

The atomization of swirling liquid sheets is investigated with numerical simulations. An algorithm that transforms the small Eulerian droplets into the Lagrangian particles is developed to reduce the computational errors in describing the interfaces. Different transforming criteria are evaluated and the grid scale criterion is shown applicable for atomization simulations of swirling sheets. Due to the complexity in the flow field, the inverse transformation is implemented when the Lagrangian particles move close to the resolved Eulerian liquid structures. First, the transforming algorithm is verified through a series of test cases. Then the algorithm is applied to investigate the atomization of a single swirling sheet. Characteristic vortical structures are identified near the interfaces. It is found that the sheet disturbances coincide with the recirculation regions. The mechanisms to break up hole structures are found to be related to surface tension and aerodynamic forces. The diameter distribution of droplets and number of liquid structures are consistent with realistic conditions. Finally the atomization of coaxial swirling liquid sheets, which is rarely investigated in detail in previous studies due to difficulties in experiments and numerical methods, is simulated with the presented algorithm. The atomization process is captured in detail. The inner and outer sheets collide and merge with each other to form a single sheet due to the pressure difference. A high pressure region at the impinging positions is generated by the strong momentum exchange between the sheets and it promotes the rapid breakup of the merged sheet. The spray characteristics and diameter distributions of droplets are obtained and compared under different injection conditions.

Longevity of small-scale (‘baby’) plumes and their role in lithospheric break-up

SUMMARYControversy between advocates of ‘active’ (plume-activated) versus ‘passive’ (driven by external tectonic stresses) modes of continental rifting and break-up has persisted for decades. To a large extent, inconsistencies between observations and models are rooted in the conceptual model of plumes as voluminous upwellings of hot material sourced from the deep mantle. Such large-scale plumes are expected to induce intensive magmatism and topographic uplift, thereby triggering rifting. In this case of an ‘active’ rifting-to-break-up system, emplacement of plume-related magmatism should precede the onset of rifting that is not observed in many rifted continental margins, thus providing a primary argument in favour of an antiplume origin for continental break-up and supercontinent fragmentation. However, mantle plumes are not restricted to whole-mantle (‘primary’) plumes emanating from the mantle-core boundary but also include ‘secondary’ plumes originating from the upper mantle transition zone or shallower. Over the last decades a number of such ‘secondary’ plumes with horizontal diameters of only ∼100–200 km (therefore, sometimes also called ‘baby’ plumes) have been imaged in the upper mantle below Europe and China. The longevity of such small-scale plumes and their impact on geodynamics of continental break-up have so far not been explored. We present results of a systematic parametrical analysis of relatively small thermal anomalies seeded at the base of the lithosphere. In particular, we explore the effects of variations in initial plume temperature (T = 1500–1700 °C) and size (diameter of 80–116 km), characteristics of the overlying lithosphere (e.g. ‘Cratonic’, ‘Variscan’, ‘Mesozoic’ and oceanic) and intraplate tectonic regimes (neutral or far-field extension of 2–10 mm yr–1). In tectonically neutral regimes, the expected decay time of a seismically detectable ‘baby’-plume varies from ∼20 to >200 Myr and is mainly controlled by its initial size and temperature, whereas the effect of variations in the thermotectonic age of the overlying lithosphere is modest. These small but enduring plumes are able to trigger localized rifting and subsequent continental break-up occurring from ∼10 to >300 Myr after the onset of far-field extension. Regardless of the thermomechanical structure of the lithosphere, relatively rapid (tens of Myr) break-up (observed in models with a hot plume and fast extension) favours partial melting of plume material. In contrast, in the case of a long-lasting (a few hundreds of Myr) pre-break-up phase (relatively cold plume, low extension rate), rifting is accompanied by modest decompressional melting of only ‘normal’ sublithospheric mantle. On the basis of the models presented, we distinguish two additional modes of continental rifting and break-up: (1) ‘semi-active’ when syn-break-up magmatism is carrying geochemical signatures of the deep mantle with deformation localized above the plume head not anymore connected by its tail to the original source of hot material and (2) ‘semi-passive’ when the site of final lithospheric rupture is controlled by a thermal anomaly of plume origin but without invoking its syn-break-up melting. These intermediate mechanisms are applicable to several segments of the passive continental margins formed during Pangea fragmentation.

Interplay between coherent and dissipative dynamics of bosonic doublons in an optical lattice

We observe the dissipative dynamics of a dense, strongly interacting gas of bosonic atom pairs in an optical lattice, controlling the strength of the two-body interactions over a wide parameter regime. We study how three-body losses contribute to the lattice dynamics, addressing a number of open questions related to the effects of strong dissipation in a many-body system, including the relationship to the continuous quantum Zeno effect. We observe rapid break-up of bound pairs for weak interactions, and for stronger interactions we see doublon decay rates that are asymmetric when changing from attractive and repulsive interactions, and which strongly depend on the interactions and on-site loss rates. By comparing our experimental data with a theoretical analysis of few-body dynamics, we show that these features originate from a non-trivial combination of dissipative dynamics described by a lattice model beyond a standard Bose-Hubbard Hamiltonian, and the modification of three-atom dynamics on a single site, which is generated alongside strong three-body loss. Our results open new possibilities for investigating bosonic atoms with strong three-body loss features, and allow for the better understanding of the parameter regimes that are required to realize strong effective three-body interactions.

Extensional tectonics and post-rift magmatism in the southern South China Sea: New constraints from multi-channel seismic data

In this study, we investigated the extensional tectonics and post-rift magmatism in the southern South China Sea (SCS) using a newly obtained seismic reflection profile, which crosses the Southwest sector of the oceanic basin (SWSOB), West Liyue Trough and Liyue Basin along the southern margin of the SCS. A wide range of magmatic features was identified in the SWSOB, with a late stage marked by a broad Pleistocene unconformity separating horizontal sediment layers from strata deformed by igneous structures. Along the continental slope, most fault activity continued until Horizon T4 (15.5 Ma), implying that crustal extension continued during seafloor spreading in the SW oceanic sector of the SCS. A low-angle listric normal fault with a large offset, marking the southern boundary of the trough, controlled regional crustal extension. Thick syn-rift sedimentary strata and significant crustal thinning in the southern part of the trough reveal relatively strong extension. Post-rift magmatism occurred in this thinned crust and affected sedimentary strata up to the seafloor. Importantly, a series of high-angle normal faults rapidly deepened the top of the basement, forming a sharp contact between the continental slope and oceanic basin. The distal domain is very narrow (~20 km) with no known detachment faults, suggesting rapid continental breakup that may be related to the presence of rigid blocks near the study area. • A low-angle listric normal fault controlled crustal extension of the southern West Liyue Trough. • The continental slope shows a sharp boundary with the ocean basin via a group of high angle normal faults. • The formation of a narrow distal domain is related to the presence of adjacent rigid crustal blocks.

Stratigraphy and Paleobiology of the Upper Cretaceous-Lower Paleogene Sediments from the Trans-Saharan Seaway in Mali

An epicontinental sea bisected West Africa periodically from the Late Cretaceous to the early Eocene, in dramatic contrast to the current Sahara Desert that dominates the same region today. Known as the Trans-Saharan Seaway, this warm and shallow ocean was a manifestation of globally elevated sea level associated with the rapid break-up of the supercontinent Gondwana in the late Mesozoic. Although it varied in size through time, the Trans-Saharan Seaway is estimated to have covered as much as 3000 km2 of the African continent and was approximately 50 m deep. The edges of the sea were defined in part by the high topography of the Precambrian cratons and mobile belts of West Africa. Over its approximately 50 million year episodic existence, through six major periods of transgression and regression, the Trans-Saharan Seaway left behind extensive nearshore marine sedimentary strata with abundant fossils. The waters that yielded these deposits supported and preserved the remains of numerous vertebrate, invertebrate, plant, and microbial species that are now extinct. These species document a regional picture of ancient tropical life that spanned two major Earth events: the Cretaceous-Paleogene (K-Pg) boundary and the Paleocene-Eocene Thermal Maximum (PETM). Whereas extensive epeiric seas flooded the interior portions of most continents during these intervals, the emerging multicontinental narrative has often overlooked the Trans-Saharan Seaway, in part because fundamental research, including the naming of geological formations and the primary description and analysis of fossil species, remained to be done. We provide such synthesis here based on two decades of fieldwork and analyses of sedimentary deposits in the Republic of Mali. Northern parts of the Republic of Mali today include some of the farthest inland reaches of the ancient sea.We bring together and expand on our prior geological and paleontological publications and provide new information on ancient sedimentary rocks and fossils that document paleoequatorial life of the past. Ours is the first formal description of and nomenclature for the Upper Cretaceous and lower Paleogene geological formations of this region and we tie these names to regional correlations over multiple modern territorial boundaries. The ancient seaway left intriguing and previously unclassified phosphate deposits that, quite possibly, represent the most extensive vertebrate macrofossil bone beds known from anywhere on Earth. These bone beds, and the paper shales and carbonates associated with them, have preserved a diverse assemblage of fossils, including a variety of new species of invertebrates and vertebrates, rare mammals, and trace fossils. The shallow marine waters included a wide range of paleoenvironments from delta systems, to hypersaline embayments, protected lagoons, and carbonate shoals.Our overarching goal has been to collect vertebrate fossils tied to a K-Pg stratigraphic section in Africa. We provide such a section and, consistent with prior ideas, indicate that there is a gap in sedimentation in Malian rocks in the earliest Paleocene, an unconformity also proposed elsewhere in West Africa. Our phylogenetic analyses of several vertebrate clades across the K-Pg boundary have clarified clade-by-clade species-level survivorship and range extensions for multiple taxa. Few macrofossil species from the Trans-Saharan Seaway show conspicuous change at either the K-Pg boundary or the PETM based on current evidence, although results are very preliminary. Building on our earlier report of the first record of rock-boring bivalves from the Paleocene of West Africa, we further describe here a Cretaceous and Paleogene mollusk fauna dominated by taxa characteristic of the modern tropics. “This abstract has been truncated. To view the complete abstract please download the PDF”

Geochronology and geochemistry of tuffaceous rocks from the Banxi Group: Implications for Neoproterozoic tectonic evolution of the southeastern Yangtze Block, South China

The Neoproterozoic tectonic evolution of South China is important for understanding the tectonic assembly of modern East Asia. As a key sedimentary-volcanic sequence, the Banxi Group in South China contains a wealth of information on the genesis of the Nanhua rift basin, which is linked to the assembly and breakup of the Rodinia supercontinent. However, the geochronological and tectonic signatures of the Banxi Group in the Jiangnan orogenic belt are still controversial. In this study, the tuffaceous rocks in the Banxi area were analyzed with regard to their whole-rock major- and trace-element concentrations, and zircons in the tuffaceous rocks were analyzed for LA-(MC)-ICPMS U–Pb ages, trace elements and Hf isotopic compositions. These rocks are well preserved and show high concentrations of SiO2 (61.7–72.3%), K2O (1.7–4.5%), Al2O3 (8.4–18.9%), Rb (55–195 ppm) and Th (4.3–12.4 ppm), low concentrations of TiO2 (0.24–0.95%), Sr (54–128 ppm), Nb (5.6–12.1 ppm) and Ta (0.4–0.9 ppm), LREE enrichment (LaN/YbN = 6.6–14.7), and negative Eu anomalies (Eu/Eu* = 0.45–0.85). They have chemical affinities with high-K calc-alkaline S-type granites and exhibit continental volcanic-arc characteristics. The zircons are magmatic in origin and yield a U-Pb age distribution with three peaks: (1) Neoproterozoic (597–949 Ma, mostly 761–788 Ma), (2) Mesoproterozoic (1122–1387 Ma), and (3) Paleoproterozoic (1952–2605 Ma). The Neoproterozoic zircons yield slightly different, but overlapping, mean ages as a function of lithology: 770.2 ± 3.7 Ma for tuffaceous siltstones, 768.2 ± 6.7 Ma for tuffs, and 766.4 ± 5.2 Ma for tuffaceous slates. All zircons in the study units exhibit high U/Yb ratios (0.1–0.6) and low Hf (7106–12554 ppm) and Y (305–6617 ppm) contents, suggesting continental crustal derivation. Some of the zircons have larger LREE contents and smaller Ce anomalies relative to typical magmatic zircons, suggesting later fluid modification. The Neoproterozoic zircons have εHf(t) values ranging from −16.5 to 16.7 (mostly −8 to 10), corresponding to crustal model ages (TDMC) of 0.97–2.73 Ga. These ages imply a mixture of juvenile (i.e., Neoproterozoic) arc-derived material and Paleoproterozoic heterogeneous crust as magmatic sources for the tuffaceous sequences. Based on our integrated dataset, we infer that the Banxi tuffaceous rocks were extrusive equivalents of S-type granitoids that show volcanic-arc affinities but that were nonetheless deposited in a post-collisional and subsequent rifting-related extensional setting within the newly amalgamated South China Block. We account for this apparent contradiction by proposing that, following collision of the Yangtze and Cathaysia blocks, a rapid breakup of the continental arc caused by deep mantle upwelling led to initiation of post-collisional extension and rifting in the Nanhua Basin.

Pediatric Chalazion Case Report

Background and Objectives
 A chalazion, also known as a stye, is a common and chronic inflammatory problem of the eyelids where one or more Meibomian glands are blocked. Previous studies have shown that a chalazion is a sign of Meibomian Gland Dysfunction (MGD) and evaporative dry eye disease. The prevalence of chalazia in the pediatric population has recently been noted. In this report, we will describe two pediatric cases of chalazion that are associated with MGD and related dry eye disease. 
 Methods
 This is a case report of non-genetically related 7-year-old and 16-year-old patients as they were each seen for newly developed chalazia.
 Results
 External exam in both patients showed chalazia, waxy plugs and poor Meibomian gland expression. Meibography showed shorten, truncated, and dilated Meibomian glands with rapid tear break-up times leading to the diagnosis of evaporative dry eye disease due to MGD.
 Conclusion
 These cases serve to confirm an increase in the prevalence of MGD in the pediatric population and to emphasize the need for early screening for dry eye disease. 
 Key Words: Chalazion - Meibomian gland dysfunction - Pediatric Dry Eye Disease

Union break-up after HIV diagnosis among sub-Saharan African migrants in France: disclosing HIV status is linked with staying in union

ABSTRACTSub-Saharan African migrants living in France are particularly affected by HIV. Due to the fear of sexual transmission of the virus, those in a relationship could experience a union break-up after an HIV diagnosis. Based on data from the time-event ANRS-Parcours survey that was conducted among a representative sample of sub-Saharan migrants living with HIV (France, 2012–2013), we studied union break-ups after HIV diagnosis among people who were in a relationship at the time of their diagnosis. Women experienced a more rapid union break-up after HIV diagnosis than did men. The living conditions of men were not correlated to their risk of union break-up while among women, having a personal dwelling reduced the risk of union break-up. For both sexes, less established relationships were more likely to break up after HIV diagnosis. Having disclosed the HIV status to a partner was associated with a reduced risk of separation between partners, after adjustment on socio-economic conditions and migration characteristics.

Evaluating the Effects of Climate Change on Indigenous Marine Mammal Hunting in Northern and Western Alaska Using Traditional Knowledge

Inupiaq, Yup’ik, and Cup’ik hunters in 14 Alaska Native communities described a rapidly changing marine environment in qualitative traditional knowledge interviews conducted over the course of a decade with 110 individuals. Based on their observations, sea ice conditions are the most notable change, with later freeze-up, thinner and less reliable ice, and earlier and more rapid break-up. Marine mammal populations in northern and western Alaska have been affected by changes in the physical environment, with alterations to migratory timing and routes, distribution, abundance, health, and behavior. Despite these changes, marine mammal populations in the region remain generally healthy and abundant. For hunters, access is the biggest challenge posed by changing conditions. Sea ice is less safe for travel, particularly for more southerly communities, making hunting more dangerous or impossible. Rapid break-up has reduced the time available for hunting amid broken ice in spring, formerly a dependable and preferred season. Social change also affects the ways in which hunting patterns change. Increased industrial development, for example, can also alter marine mammal distribution and reduce hunting opportunity. Reduced use of animal skins for clothing and other purposes has reduced demand. More powerful and reliable engines make day trips easier, reducing the time spent camping. An essential component of adjustment and adaptation to changing conditions is the retention of traditional values and the acquisition of new information to supplement traditional knowledge. Our findings are consistent with, and add detail to, what is known from previous traditional knowledge and scientific studies. The ways in which hunters gather new information and incorporate it into their existing understanding of the marine environment deserves further attention, both as a means of monitoring change and as a key aspect of adaptation. While the changes to date have been largely manageable, future prospects are unclear, as the effects of climate change are expected to continue in the region, and ecological change may accelerate. Social and regulatory change will continue to play a role in fostering or constraining the ability of hunters to adapt to the effects of climate change.

Analysis of the dynamic pressure from ex-vessel steam explosion for pressurized water reactor

In a nuclear reactor severe accident, the molten core debris may cause steam explosion when contacting with water in the reactor cavity below the reactor pressure vessel (RPV), which can endanger the containment integrity of the nuclear power plant. In this study, the improved FCI computer code TEXAS-VI considering solidification effects and the original code TEXAS-V were used to analyze the TROI TS-3 test as a benchmark experiment. Then a series of ex-vessel steam explosion simulations were performed. In the experimental comparison, the melt penetration (leading front position in the coolant) in TS-3 was well predicted by TEXAS. The pressure at different positions simulated by TEXAS-VI was notably lower than that of TEXAS-V, but in good agreement with the experiment results. The simulation results showed that the modeling of corium solidification during the mixing process and the breakup criteria in TEXAS-VI largely mitigates the rapid breakup, thereby affecting the steam explosion. Our study continued by using TEXAS-VI to analyze ex-vessel steam explosion energetics for a range of different initial conditions, with the aim to examine the impact of the fuel melt initial diameter and velocity. For conservative estimation, the cross sectional area ratio of the fuel-coolant mixing region to the injected corium was set to maximize the peak explosion impulse based on a number of parametric calculations. In scope of this study conditions, the larger the diameter and the initial injected velocity of corium were, the larger the maximum pressure and the liquid kinetic energy from the steam explosion were. The void fraction can influence the fragmentation rate during the explosion stage and mitigate the propagation of the pressure pulse during the propagation stage. The liquid kinetic energy would be affected by the pressure from the steam explosion and the void fraction at the end of mixing stage.

Runaway electrons and ITER

The potential for damage, the magnitude of the extrapolation, and the importance of the atypical—incidents that occur once in a thousand shots—make theory and simulation essential for ensuring that relativistic runaway electrons will not prevent ITER from achieving its mission. Most of the theoretical literature on electron runaway assumes magnetic surfaces exist. ITER planning for the avoidance of halo and runaway currents is focused on massive-gas or shattered-pellet injection of impurities. In simulations of experiments, such injections lead to a rapid large-scale magnetic-surface breakup. Surface breakup, which is a magnetic reconnection, can occur on a quasi-ideal Alfvénic time scale when the resistance is sufficiently small. Nevertheless, the removal of the bulk of the poloidal flux, as in halo-current mitigation, is on a resistive time scale. The acceleration of electrons to relativistic energies requires the confinement of some tubes of magnetic flux within the plasma and a resistive time scale. The interpretation of experiments on existing tokamaks and their extrapolation to ITER should carefully distinguish confined versus unconfined magnetic field lines and quasi-ideal versus resistive evolution. The separation of quasi-ideal from resistive evolution is extremely challenging numerically, but is greatly simplified by constraints of Maxwell’s equations, and in particular those associated with magnetic helicity. The physics of electron runaway along confined magnetic field lines is clarified by relations among the poloidal flux change required for an e-fold in the number of electrons, the energy distribution of the relativistic electrons, and the number of relativistic electron strikes that can be expected in a single disruption event.

A visualized study of the motion of individual bubbles in a venturi-type bubble generator

As an equipment for generating millimeter- or micrometer-sized bubbles, venturi-type bubble generator has a great potential application in online poison gas removal for molten salt reactor, water treatment, mineral flotation, flue gas desulphurization, even in drug delivery, etc. While the process of generating bubbles in a venturi tube is quite different from that in a conventional tube. A visualized study was carried out to illustrate the details of the transportation of individual bubbles in a venturi-type bubble generator. Sizes, velocity, acceleration of the bubbles were obtained by Digital Image Analysis (DIA) method. An extremely rapid deceleration and intense breakup process was observed nearby the entrance of the diverging section of the bubble generator. Bubbles with average diameter larger than 1.5 mm were usually split before collapse, while the smaller one collapsed directly without split. Within several millimeters, the velocity of the bubbles were almost reduced by half, which is believed to play a key role for triggering their collapse. Once a bubble was decelerated to its minimum velocity, it was collapsed promptly into many tiny bubbles around the position of 8–10 mm from the inlet of the diverging section. Increasing the liquid flow rate could intensify the collapse process, while its influence on the position of collapse was weak.

Tribology of swollen starch granule suspensions from maize and potato

The tribological properties of suspensions of cooked swollen starch granules are characterised for systems based on maize starch and potato starch. These systems are known as granule ⿿ghosts⿿ due to the release (and removal) of polymer from their structure during cooking. Maize starch ghosts are less swollen than potato starch ghosts, resulting in a higher packing concentration and greater mechanical stability. In a soft-tribological contact, maize ghost suspensions reduce friction compared to the solvent (water), generate bell-shaped tribological profiles characteristic of particle entrainment and show a marked concentration dependence, whereas potato ghost suspensions exhibit lubrication behaviour similar to water. Microscopy analysis of the samples following tribological testing suggests that this is due to the rapid break-up of potato ghosts under the shear and rolling conditions within the tribological contact. A reduction in the small deformation moduli (associated with a weak gel structure) is also observed when the potato ghost suspensions are subjected to steady shear using parallel plate rheometry; both microscopy and particle size analysis show that this is accompanied by the partial shear-induced breakage of ghost particles. This interplay between particle microstructure and the resultant rheological and lubrication dynamics of starch ghost suspensions contributes to an enhanced mechanistic understanding of textural and other functional properties of cooked starches in food and other applications.