Quiescent Period Research Articles

Analysis of Peripapillary Retinal Nerve Fiber Layer Thickness in Acute Anterior Uveitis among Children with HLA-B27-Positive Juvenile Idiopathic Arthritis.

The aim of this study was to evaluate changes in the thickness of the peripapillary retinal nerve fiber layer (pRNFL) in children with a diagnosis of juvenile idiopathic arthritis (JIA) who were positive for human leukocyte antigen (HLA)-B27, treated for the first episode of unilateral acute anterior uveitis (AAU). This retrospective study included 41 children (aged 5 to 14 years; mean age 8.32 ± 2.4 years) with HLA-B27 positivity and unilateral JIA-AAU, and 40 healthy children. Optical coherence tomography (OCT) imaging was performed during active inflammation and subsequent noninflammatory phases (6 months after the resolution of inflammatory symptoms in the anterior segment of the eye). There was a marked difference in mean pRNFL thickness between eyes with AU in the active phase, unaffected fellow eyes and the control group (110.22 ± 5.95 μm, 102.39 ± 4.39 μm and 95.83 ± 8.84 μm, respectively; p < 0.001). The thickness of pRNFL in eyes with AU in the active phase in all sectors was greater compared to unaffected fellow eyes (p < 0.001) and normal eyes (p < 0.001). In addition, it was demonstrated that pRNFL thickness was significantly increased in the superior and temporal sectors in the unaffected fellow eyes compared to the control group (128.73 ± 13.16 μm vs. 121.48 ± 13.35 μm and 71.37 ± 4.02 μm vs. 64.98 ± 9.12 μm, respectively). Even during the inactive phase, eyes with AU, compared to the healthy control group, had significantly greater pRNFL thickness in the inferior sector (129.78 ± 11.98 μm vs. 122.3 ± 14.59 μm; p = 0.018), along with the temporal sector (70.88 ± 5.48 μm vs. 64.98 ± 9.12 μm; p = 0.001). An increase in pRNFL thickness in children with unilateral JIA-AAU who were positive for HLA-B27 antigen can be observed in both eyes compared to healthy controls, and this change may persist even after the inflammatory symptoms have resolved. Measurements of pRNFL thickness resulting from JIA-AU-associated glaucoma should be performed during quiescent periods to avoid subclinical changes in pRNFL thickness caused by inflammation. However, when reviewing the results, it should be noted that changes in pRNFL parameters may be present despite evidence of a resolution of inflammation.

A long time of rest at Llaima volcano following the 2010 MW 8.8 Maule earthquake, Chile

Llaima Volcano (38.692°S, 71.729°W) is one of the most active centers in South America, with ∼56 eruptions since 1852 CE. During the last eruptive cycle (2007–2009), the volcano displayed typical features of open conduit systems, with frequent long-period volcanic seismicity (LP). After the MW 8.8 Maule megathrust earthquake (27 February 2010), Llaima volcano located 305 km to SE of the epicenter, has experienced one of the longest periods of quiescence since 1852, with reduced activity observed since the beginning of its continuous instrumental monitoring in the year 2007. To better understand this behavior, we track the repose time between eruptions in the 20th century to depict the current period of quiescence and provide details of the pattern of volcano seismicity after the earthquake. The number of LP events decreased ∼90% shortly after the earthquake. In turn, crustal faults nearby (∼20 km south of the main crater) showed an increased level of seismicity lasting for approximately six months after the mainshock before returning to background levels. In order to propose driving mechanisms for such behavior, we computed the static changes of the stress tensor on chosen receiver structures. The acting receiver structure differs from those related to the long-term stress regime controlled by regional tectonics and was inferred from the pre-earthquake shallow seismicity (2007–2009). LP and volcanotectonic seismicity (VT) before the earthquake were located in a NW-SE pattern, in contrast to the NE-trending alignment of flank vents (and hence dike swarms) usually interpreted as an indicator of the maximum horizontal stress axis. From the static stress transfer imparted by the earthquake, we find that an opening event would have occurred at a NW-trending receiver structure coupled with closing of other potential structures, which promoted magma storage along this blind structure but precluding further propagation to the surface. Our results thus show a rare example of earthquake-induced suppression of volcanic activity, where the geometry of the fault-fracture network that shape the plumbing system likely plays a major role.

Cratonic basins as effective sediment barriers in continent-scale sediment routing systems of Paleozoic North America

Provenance studies demonstrate the important control of plate boundary mountain building on continental sediment routing systems. Less well understood is if subsidence and uplift in cratons also has the potential to affect the organization of sediment routing systems on continental scales. New detrital zircon provenance data from the Michigan Basin in the Midcontinent of North America preserve evidence of intrabasin provenance heterogeneity in Cambrian, Ordovician, and middle Devonian strata. These results suggest that cratonic basins serve as effective sediment barriers that prevent mixing within and across basins from 10 to 100 s of millions of years. Internal sediment mixing, sorting, and dispersal may be achieved by a combination of sedimentary processes and inherited low relief topography. These observations are consistent with provenance data sets from eastern Laurentian Midcontinent basins that show locally and regionally variable provenance signatures during the early Paleozoic. By the late Devonian, provenance signatures throughout the basins homogenized, consistent with the emergence of transcontinental sediment transport systems associated with Appalachian orogenesis at the plate margin. These results demonstrate the importance of cratonic basins on local and regional sediment routing systems suggesting that these features may impede the integration of continental-scale sediment routings systems, particularly during periods of plate margin quiescence.

Observations of Fog‐Aerosol Interactions Over Central Greenland

AbstractSupercooled fogs can have an important radiative impact at the surface of the Greenland Ice Sheet, but they are difficult to detect and our understanding of the factors that control their lifetime and radiative properties is limited by a lack of observations. This study demonstrates that spectrally resolved measurements of downwelling longwave radiation can be used to generate retrievals of fog microphysical properties (phase and particle effective radius) when the fog visible optical depth is greater than ∼0.25. For 12 cases of fog under otherwise clear skies between June and September 2019 at Summit Station in central Greenland, nine cases were mixed‐phase. The mean ice particle (optically‐equivalent sphere) effective radius was 24.0 ± 7.8 µm, and the mean liquid droplet effective radius was 14.0 ± 2.7 µm. These results, combined with measurements of aerosol particle number concentrations, provide evidence supporting the hypotheses that (a) low surface aerosol particle number concentrations can limit fog liquid water path, (b) fog can act to increase near‐surface aerosol particle number concentrations through enhanced mixing, and (c) multiple fog events in quiescent periods gradually deplete near‐surface aerosol particle number concentrations.

Authigenic Carbonate Precipitation at Yam Seep Controlled by Continuous Fracturing and Uplifting of Four‐Way Closure Ridge Offshore SW Taiwan

AbstractHydrocarbon seeps are common manifestations of gas leakage from the seafloor. However, the fate of methane seepage within the gas hydrate stability zone at active margins is poorly constrained. This study presents a 40‐thousand‐year record of hydrocarbon seepage archived by a ∼5‐m long core composed of authigenic carbonate from the Yam Seep area, Four‐Way Closure Ridge off SW Taiwan. Different carbonate microfacies could be distinguished: Consolidated microcrystalline aragonite representing lithified host sediments intercalated by pure aragonite present in 10–50 cm thick intervals in the core. These aragonite intervals are interpreted as having precipitated within former fractures in the host rock. High resolution U‐Th dating of these aragonites is interpreted to record the minimum age of the opening of these fractures. The chronology of aragonite precipitation throughout the core suggests a record of continuous seepage from ∼41 to 2 ka that fluctuated in intensity over this time period. The chronology of putative fracturing events and observed carbonate precipitation suggest (a) an active period of fracturing and seepage from ∼37 to 27 ka, (b) a more quiescent period from ∼27 to 16 ka, followed by (c) another active period from ∼16 to 12 ka. A schematic model illustrates the evolution of carbonate formation within the core influenced by faulting, fracturing, erosion, gas hydrate accumulation, and aragonite precipitation and provides a unique 40,000‐year‐old record of methane seepage and crucial insights into the dynamics of long‐term seepage systems at active margins.

The sedimentary facies and tectono-stratigraphic successions of the Carboniferous–Lower Permian deposits in western South Qiangtang Block: Implication for a rifting process on the Gondwana margin

The South Qiangtang Block (SQB) was widely acknowledged as a part of the Cimmerian Continent, which rifted away from Gondwanan margin during the Early Permian. However, the sedimentary response to this rifting event has thus far not been unequivocally confirmed, which makes this event ambiguous. In this contribution, three stratigraphic successions are recognised, which are characterised by distinct facies and record different stages in the tectonic evolution of the basin and associated changes in the rates of basin subsidence and sediment accommodation. Succession 1 comprises glacio-marine deposits which are dominated by dark shales and diamictites (Cameng and Zhanjin formations) originated mainly from both gravity flow and downslope resedimentation. Succession 2 is predominated by shallow-water sandstones of delta setting (lower Qudi Formation). Succession 3 is composed of deposits of tidal flat and platform (upper Qudi and Tunlonggongba formations). The sedimentary facies changes fit well with marine rift-basin successions: (1) Succession 1 clearly records ‘sediment underfilled’ stage characterised by rapid tectonic subsidence, low sediment supply, and marks an early to climax stage of syn-rift; (2) deltaic sandstones facies of Succession 2 records ‘sediment filled and overfilled’ when sediment supply consumes up the accommodation, and marks a late stage of syn-rift during the tectonic quiescence period; (3) tidal-rhythmites of Succession 3 is likely a record of short-term autogenic cycles, indicating a possible post-rift stage. Therefore, these successions within the western SQB during the Early Permian was best explained by the tectonic subsidence resulted from the rifting of the SQB from the Gondwanan margin.

PA27 Patient-initiated follow-up in an Irish dermatology department: a pilot study

Abstract Patient-initiated follow-up (PIFU) is an alternative approach to a traditional appointment-based system, offering flexible review for patients, and has successfully been implemented across a range of specialty departments worldwide. In 2022, the Health Service Executive in Ireland announced reforms to introduce ‘patient-initiated review’ across the organization in its strategy to tackle long patient waiting lists. More recently, the British Association of Dermatologists developed guidelines to support dermatology departments within the National Health Service to introduce PIFU pathways successfully. We performed a single centre, prospective pilot study of patients offered PIFU over a 3-month period in 2021. Patients were identified through electronic reports for adult and paediatric dermatology clinics, and data were drawn from clinical records. Patients were offered ‘flexible’ review within 1 year of the original presentation pertaining to the same clinical condition. Patient demographics and clinical details were extracted and analysed, and patients followed for a 12-month period. Forty-seven patients were identified. Fifty-seven per cent (n = 27) were female and the median age was 23 years (range 0–83). Clinical diagnoses included acne (n = 13), eczema (n = 8), nonspecific rash (n = 4), infection (n = 5), nonmelanoma skin cancer (n = 3), urticaria (n = 2), hidradenitis suppurativa (n = 2), actinic keratosis (n = 2), guttate psoriasis (n = 2), vasculitis (n = 2) and other (n = 4). Thirty per cent (n = 14) of patients activated PIFU within a 12-month period. Median time until PIFU was 213 days (range 28–413). Fifty-seven per cent (n = 8/14) were paediatric patients. Forty-three per cent (n = 6/14) of patients had acne, 29% (n = 4/14) eczema, 14% (n = 2) actinic keratosis, 7% (n = 1), urticaria and 7% (n = 1) guttate psoriasis. The background rate of patients who ‘did not attend’ (DNA) in 2021 was 12% (n = 823/7093). This study demonstrates how PIFU has a useful role in reducing unnecessary attendance at outpatient clinics. Previous research has demonstrated its benefits in patients with chronic conditions who require lifelong management. Our findings support the view that PIFU has a role in dermatology for patients with conditions that display periods of quiescence, as seen in inflammatory dermatoses. Early review allows for the appropriate escalation of treatment to avoid potential complications. This study shows that PIFU can have a positive impact on DNA rates. In 2021, the departmental DNA rate was lower than the estimated annual national rate of 13%. The PIFU avoids unnecessary review of well patients, reducing the potential for nonattendance. Furthermore, 70% of patients were successfully discharged after 12 months. The PIFU may complement strategies such as nurse-led clinics and teledermatology in increasing outpatient capacity and reducing patient waiting lists. Further larger studies focusing on client and resource benefits of PIFU can guide specialty-specific policies for its use across institutions in the future.

Tracking volcanic explosions using Shannon entropy at Volcán de Colima

The main objective of this work is to show that Shannon Entropy (SE) calculated on continuous seismic signals can be used in a volcanic eruption monitoring system. We analysed three years of volcanic activity of Volcán de Colima, México, recorded between January 2015 and May 2017. This period includes two large explosions, with pyroclastic and lava flows, and intense activity of less energetic explosion, culminating with a period of quiescence. In order to confirm the success of our results, we used images of the Visual Monitoring system of Colima Volcano Observatory. Another of the objectives of this work is to show how the decrease in SE values can be used to track minor explosive activity, helping Machine Learning algorithms to work more efficiently in the complex problem of distinguishing the explosion signals in the seismograms. We show that the two big eruptions selected were forecasted successfully (6 and 2 days respectively) using the decay of SE. We conclude that SE could be used as a complementary tool in seismic volcano monitoring, showing its successful behaviour prior to energetic eruptions, giving time enough to alert the population and prepare for the consequences of an imminent and well predicted moment of the eruption.

A study of magnesium dissolution from serpentinites composed of different serpentine group minerals

An innovative approach to the acid processing of serpentinites was applied to serpentinites samples consisting largely of one or two species of the three important serpentine group minerals (Mg, Fe)3Si2O5(OH)4: chrysotile, lizardite and antigorite. The innovation lies in keeping a serpentinite sample grinded (100–200 μm) in a state of quiescence for different periods of time (0, 10, 30, 60, and 240 min) in the solution prepared by a ten-minute agitation of this sample in the boiling leach solution (95 °C) of hydrochloric acid (HCl 8–10%). The influence of this period of quiescence on serpentine minerals dissolution was judged from the amount of magnesium measured in the solution. The data derived from experimental studies have revealed that serpentinites composed of chrysotile and lizardite minerals display the higher degree of magnesium extraction in comparison to the ones largely made up of antigorite mineral. Furthermore, 30 min proved to be the period of quiescence that is sufficient for recovering up to about 97 % of the total magnesium present in serpentinites comprised of chrysotile and lizardite minerals. This study highlights the importance of identifying serpentine polymorphs constituting serpentinites in achieving higher yields of magnesium under mildly acidic conditions.

Timing, Thrusting Mode, and Negative Inversion Along the Circeo Thrust, Apennines, Italy: How the Accretion‐To‐Extension Transition Operated During Slab Rollback

AbstractThe evolution of the Apennine wedge has seen the time‐space migration of the forebulge, foredeep, thrust wedge, and back‐arc extension phases in the wake of the Eastward rollback of the subducting Adria slab. In this framework, thrusting and post‐orogenic extensional faulting have occurred in two parallel forelandward‐migrating ribbons, with extensional deformation overprinting or partly exploiting anisotropies of the inherited thrust system. Here, we explore the tectonic framework and the timing of thrusting and subsequent negative inversion of the Circeo thrust, one of the major thrusts in the inner portion of the central Apennines, with the main aim to constrain the timing and mode of the compression to extension switch. Structural analysis, carbonate C and O and clumped isotopes analysis, X‐ray diffraction of clay minerals, and U‐Pb dating of calcite slickenfibers have been integrated with seismic interpretation, cross‐section balancing, and 1D burial and thermal modeling. We show that the Circeo thrust developed during Langhian‐Serravallian time. Its extensional reactivation is dated at the Serravallian, during the stacking of an underlying thrust slice, before the onset of Pliocene back‐arc extension in the area. Combination of our data with the age of thrusts, extensional basins, and base of the foredeep infill of the central Apennines, demonstrates that forelandward migration of the foredeep‐thrust system occurred at variable velocities. Accelerations and decelerations are synchronous, respectively, with the opening of the Liguro‐Provençal and Tyrrhenian back‐arc basins and with the interluding quiescent period.

RECURRENT ANTERIOR UVEITIS ASSOCIATED WITH MAJOR FLUCTUATIONS IN CHOROIDAL THICKNESS IN A PATIENT WITH PACHYCHOROID DISORDER.

To describe remarkable choroidal thickness fluctuations corresponding to episodes of recurrent anterior uveitis with subretinal fluid development when exceeding a choroidal thickness threshold. A patient with pachychoroid pigment epitheliopathy and unilateral acute anterior uveitis of the left eye was evaluated over a period of 3 years with multimodal retinal imaging including optical coherence tomography. Longitudinal changes in subfoveal choroidal thickness (CT) were measured and correlated with episodes of recurrent inflammation. Over the course of five recurrent episodes of inflammation in the left eye treated with oral antiviral and topical steroid therapy, subfoveal CT increased as much as 200 μm or more. By contrast, subfoveal CT in the fellow quiescent right eye was within normal limits and minimally changed throughout the follow-up. Increased CT occurred with each episode of anterior uveitis and decreased by 200 µ m or more during periods of quiescence in the affected left eye. Subretinal fluid and macular edema developed with a maximum CT of 486 μm and spontaneously resolved when CT decreased after treatment. In eyes with pachychoroid disease, anterior segment inflammation may lead to marked increases in subfoveal CT and the development of subretinal fluid at a threshold thickness value.

Unexpected departure from seismic laws with largest labquakes on model granular materials

In an effort to understand the most devastating natural earthquakes, we present a series of largest laboratory quakes on model granular materials under triaxial compression in fully drained and quasi-static shearing conditions. These largest labquakes can lead to a complete loss of normal and tangential stresses and even a destruction of the granular structure. The repeated spontaneous stick–slip frictional failures under uncontrolled triggering stress reproduce the traditional statistical seismic relations (Gutenberg–Richter, Omori–Utsu, inter-event times and productivity) with unexpected deviations created by biggest detected stick–slip motions in laboratory. A surprising long quiescent period results from these lab-quakes, contrasting the presence of numerous aftershocks following the majority of natural earthquakes. We also identify the appearance conditions of these unexpected granular instabilities. This work would have practical implications in improving qualitatively our understanding of the potentially highest magnitude earthquakes.

A blue whale (Balaenoptera musculus) feeding ground in a southern Australian coastal upwelling zone

A localised aggregation of blue whales, which may be pygmy blue whales (B. m. brevicauda), occurs in southern Australian coastal waters (between 139°45AE-143°E) during summer and autumn (December-May), where they feed on coastal krill (Nyctiphanes australis), a species which often forms surface swarms. While the abundance of blue whales using this area is unknown, up to 32 blue whales have been sighted in individual aerial surveys. Krill appear to aggregate in response to enhanced productivity resulting from the summer-autumn wind-forced Bonney Coast upwelling along the continental shelf. During the upwelling’s quiescent (winter-spring) period, blue whales appear to be absent from the region. Krill surface swarms have been associated with 48% of 261 blue whale sightings since 1998, with direct evidence of feeding observed in 36% of all sightings. Mean blue whale group size was 1.55 (SD = 0.839), with all size classes represented including calves. This seasonally predictable upwelling system is evidently a regular feeding ground for blue whales, and careful management of human activities is required there.

Payroll Employment at the Weekly Frequency

Nontraditional data can provide critical economic insights in real time. We document the development of weekly employment indexes based on microdata from the payroll processor ADP. These data have provided insights into labor market developments in the fast-moving pandemic environment of recent years, as well as in more quiescent periods. We describe processes for weighting and benchmarking, seasonally adjusting weekly data, and ultimately combining the signals from ADP and official data. Finally, we show how the weekly employment indexes have fared during the pandemic jobs recovery, focusing on revisions to official data for the second half of 2021.

Tectonic Evolution of a Sedimented Oceanic Transform Fault: The Owen Transform Fault, Indian Ocean

AbstractThe Owen transform fault (OTF) connecting the Sheba and the Carlsberg spreading ridges in the Indian Ocean currently forms the active plate boundary between India and Somalia plates. This 330‐km‐long transform fault is by far the longest transform fault along the India‐Somalia plate boundary and its valley is buried under the thick distal turbidites of the Indus Fan with total thickness ranging from 1,000 to &gt;5,000 m. A new set of seismic reflection and multibeam bathymetric data reveals remarkable transpressive structures along its entire length recorded as folds in the sedimentary cover, eruption of mud ridges at the seafloor, thrusts in the young oceanic lithosphere. Based on a new regional time‐calibration of the seismic reflectors, we show that sediments in the transform valley (post 8.6 Ma) recorded a period of tectonic quiescence until the onset of a transpressive event around 1.5–2.4 Ma that we relate to a minor change in India‐Somalia kinematics not captured by magnetic anomalies. This tectonic regime is still active based on compressive earthquakes and deformation of the most recent sediments. Transpression resulted in the formation of a proto‐median ridge and the coeval propagation of the tip of the Carlsberg Ridge into the Somalian plate. These features are typically encountered at many other transform faults but rarely captured in their very early stage.

Role of altered cortisol production in the development of sarcopenia

Skeletal muscle mass and function is decreased as we age, a condition known as sarcopenia. Ageing is associated with increases in minimum and mean cortisol plasma levels and shortening of the evening cortisol quiescent period, suggesting impaired circadian function and higher basal levels with increasing age (Stamou et al, 2023). It has also been shown that the deleterious effects of bed rest on human skeletal muscle are exacerbated by hypercortisolemia (Fitts et al, 2007).The aim of this study was to examine the direct effects of increasing levels of cortisol on muscle cells. C2C12 myoblasts were fused to myotubes by serum deprivation for up to 7 days. Cellular viability was assessed using light-microscopy to identify any gross changes in cell morphology at 3, 24 and 48 hours following treatment with a range of cortisol concentrations in the physiological range (10 – 0.1uM). Indices of muscle atrophy and evidence of altered levels of inflammatory cytokines was determined by mRNA analyses and release of cytokines/chemokines by myotubes was assessed using bead based multiplex technology (Luminex immunoassay).Cortisol treatment had no significant effect on C2C12 myotube viability at any concentration or time point, or on gene expression of IL-6, RANTES (CCL5) or MCP-1 (CCL2) compared with control untreated myotubes. No increase in the release of cytokines and chemokines from C2C12 myotubes was seen following treatment with cortisol and in some instances a significant decrease in cytokine/chemokine production was seen, particularly following treatment with higher concentrations of cortisol when compared with control values (eg, 10uM cortisol, 24 hours post-treatment: IL-6: 1.6 +/- 1.6% CXCL5: 17.4 +/- 1.8%; KC (CXCL1): 11.6 +/-10.3%. These data are in contrast to previous work from our group which revealed an increase in the release of IL-6, CXCL-1 (KC), CCL2 (MCP-1) and CCL5 (RANTES) from C2C12 myotubes following treatment of myotubes 25ng/ml TNF-α (Lightfoot et al, 2015).In summary, increased levels of cortisol do not appear to have any direct deleterious effects on myotube viability or production of pro-inflammatory cytokines. However, this does not exclude any indirect effects of cortisol on muscle including the effects on other organs indirectly affecting muscle function. It may also be that cortisol has a deleterious effect when muscle is under stressful conditions and this possibility will also be examined. Fitts et al (2007). doi: 10.1152/ajpcell.00573.2006 ; Lightfoot et al. (2015) doi: 10.1016/j.redox.2015.08.007 ; Stamou et al (2023) doi.org/10.1016/j.maturitas.2022.10.006 . The authors would like to thank the EU/BBSRC and CIMA for generous funding. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Uplift and exhumation of the Chakabeishan ore district in the northern margin of the Qaidam Basin, China: Constraints from fission track thermochronology

The Chakabeishan area is located in the northern margin of the Qaidam Basin, Northwest China, and is an important lithium mining area. However, there is a relatively lower research degree and lack of data constraints of tectonic uplift and exhumation. Using fission track technology, new apatite and zircon fission track results have been reported for the first time in order to reveal the tectonic processes and uplift histories of this area. A total of 11 sample results were obtained, these ages could be divided into four groups, namely, 159–144 Ma, 114–100 Ma, 72 Ma and 52–32 Ma, revealing four periods of tectonic activities. Thermal history modelling provided three episodes of uplift at 120–60 Ma, 60–18 Ma and 18–0 Ma. In the first stage, the Southern Qilian Mountains was reactivated and subducted southward due to collision of the Lhasa and the Qiangtang blocks, resulting in rapid uplift in this area. The second stage is tectonic quiescence period corresponding to a relatively steady uplift. The third stage showing rapid uplift caused by the collision between the Indian and Eurasian Plates. The average uplift rate and total uplift amount of the three stages calculated according to the geological thermal histories are 0.039 km/Myr and 3.27 km, respectively. Using the age–closure temperature method, the exhumation rate has been calculated as 0.034–0.148 km/Myr from zircon closure–temperature of 250 °C to apatite closure–temperature of 100 °C and 0.049–0.076 km/Myr form the apatite closure–temperature of 100 °C to 15 °C of surface temperature. The exhumation rate is fastest from the Late Cretaceous to Eocene and has then changed a little since the Eocene, with the average exhumation rate of about 0.059 km/Myr. Synthesizing the zircon ages and geological characteristics, this area is characterized by multi–stages mineralization, and the metallogenic age is mainly in the Late Jurassic–Cretaceous.

Dissociation Between Neuronal and Astrocytic Calcium Activity in Response to Locomotion in Mice.

Locomotion triggers a coordinated response of both neurons and astrocytes in the brain. Here we performed calcium (Ca2+) imaging of these two cell types in the somatosensory cortex in head-fixed mice moving on the airlifted platform. Ca2+ activity in astrocytes significantly increased during locomotion from a low quiescence level. Ca2+ signals first appeared in the distal processes and then propagated to astrocytic somata, where it became significantly larger and exhibited oscillatory behaviour. Thus, astrocytic soma operates as both integrator and amplifier of Ca2+ signal. In neurons, Ca2+ activity was pronounced in quiescent periods and further increased during locomotion. Neuronal Ca2+ concentration ([Ca2+]i) rose almost immediately following the onset of locomotion, whereas astrocytic Ca2+ signals lagged by several seconds. Such a long lag suggests that astrocytic [Ca2+]i elevations are unlikely to be triggered by the activity of synapses among local neurons. Ca2+ responses to pairs of consecutive episodes of locomotion did not significantly differ in neurons, while were significantly diminished in response to the second locomotion in astrocytes. Such astrocytic refractoriness may arise from distinct mechanisms underlying Ca2+ signal generation. In neurons, the bulk of Ca2+ enters through the Ca2+ channels in the plasma membrane allowing for steady-level Ca2+ elevations in repetitive runs. Astrocytic Ca2+ responses originate from the intracellular stores, the depletion of which affects subsequent Ca2+ signals. Functionally, neuronal Ca2+ response reflects sensory input processed by neurons. Astrocytic Ca2+ dynamics is likely to provide metabolic and homeostatic support within the brain active milieu.

A storm driven turbidity maximum in a microtidal estuary

Many macro- and mesotidal estuaries are characterized by Turbidity Maxima Zones (TMZs), regions with suspended solid concentrations that are much higher than those found throughout the rest of the estuary. Such regions are located near the upriver limit of salt intrusion and their position and extent are modulated and driven by tidal oscillations, especially in estuaries where tidal forcing is large. Hence, pronounced TMZs are not typically expected in micro-tidal estuaries. Field experiments were carried out in the microtidal estuary of the Misa River (northeast coast of Italy) with the aim to analyze riverine-coastal ocean interactions during different climatic conditions, freshwater discharge and tidal forcing. The goal was also that of identifying factors and episodic conditions that could lead to the evolution of ephemeral TMZs in this microtidal estuarine system. Observational results, combined to a flocculation model suite, describe the hydrodynamics, morphological bed evolution, water chemistry and floc dynamics within the estuary during wintertime quiescent and stormy periods. Pronounced TMZs with different location and extent were observed during two storms with different intensities, when enhanced freshwater discharge, wave action and tidal oscillation generated significant stratification of the lower estuarine water column. Higher turbidity values were observed throughout the TMZ during the smaller/weaker storm, while stronger surface mixing during the stronger storm led to greater dispersion of the (re-)suspended particulate load throughout the upper water column, providing a less pronounced TMZ along the bed of the lower estuary. Observations in the Misa River, potentially valid for other microtidal estuaries, show that: 1) episodic storm conditions that significantly increase freshwater discharge can lead to the evolution of an ephemeral TMZ that is modulated, but not controlled, by tidal oscillations and surface mixing conditions; 2) ephemeral TMZ localization, intensity, and extent during episodic storm events is a function of storm intensity; 3) moderately enhanced freshwater flow during an episodic storm event promotes a high degree of stratification, allowing for the formation of large flocs with great settling rates, leading to a pronounced TMZ forming downriver of the landward limit of seawater intrusion; whereas higher freshwater flows during stronger storm events lead to less stratification, greater bottom turbulence and potential TMZ suppression near the riverbed, with shear conditions promoting smaller flocs with lower settling and a greater potential for suspended particulate export from the lower estuary to coastal waters.

Temporally variable recurrence regimes of mega-tsunamis in the 6500 years prior to the 2004 Indian Ocean event

The analyses of cores retrieved from three sites near Port Blair (South Andaman) revealed out-of-sequence deposits at various depths. They are identified as previous episodes of tsunami by their sediment characteristics and microfossil content, using the 2004 event deposition as a template. These deposits have median ages of 601 cal. yr BP, 837 cal. yr BP, 1440 cal. yr BP, 3018 cal. yr BP, 3591 cal. yr BP, 4712 cal. yr BP, 5607 cal. yr BP, and 6357 cal. yr BP and are chronologically equivalent of those from the far-field locations in the Indian Ocean region. The distant deposits that are correlated with the South Andaman sites most likely owe their origin to the 2004-type events, as indicated by tsunami simulations in the study region. The long-term record presented here is characterized by an early phase of a quasiperiodic recurrence regime that transitions into a distinct interval of temporally clustered events. The quasiperiodic regime that appears around the mid-Holocene with an inter-event interval of 980 ± 385 years is followed by a sizable quiescent period of 1605 ± 245 years, before being succeeded by a regime of temporally clustered events. The chronology of nine tsunami events in the last 6500 years from the Indian Ocean region, thus implies a nonlinear pattern for the causative earthquakes. As demonstrated in the subduction zones elsewhere, the temporal variability of tsunamigenic great earthquakes is supported by the theoretical models espousing the characteristics of long-term stress recycling processes active within the subduction zones and transfer processes between the lower viscoelastic layer and the upper seismogenic crust.