Quiescence Time Research Articles

Unravelling the pre-eruptive conditions of the rhyolitic Šumovit Greben lava dome from clinopyroxene-dominant glomeroporphyritic clots

Detailed analyses of mineral composition and whole-rock geochemical data helped to unravel the volcanic plumbing system beneath the rhyolitic Šumovit Greben lava dome, the westernmost member of the Kožuf-Voras volcanic system (N. Macedonia). It is characterized by high SiO2 content (> 70 wt%) coupled with low MgO (< 1 wt%) and Sr (< 500 ppm) suggesting fractionation of clinopyroxene and plagioclase at depth forming a crystal mush and a crystal-poor rhyolitic lens by fractional crystallization and melt extraction on top of it. The crystal mush is composed of mainly clinopyroxene, biotite and plagioclase, whereas sanidine and plagioclase are the most abundant phenocrysts of the rhyolitic lens. The main dome forming event occurred at ca. 2.9 Ma, which sampled the crystal-poor rhyolitic lens. After a short quiescence time, an explosive eruption occurred depositing a massive lapilli tuff layer northwest of the lava dome, and an extrusion of a small-volume lava flow on the northern side of the lava dome at ca. 2.8 Ma. This latter sampled also the crystal mush, as it contains abundant glomeroporphyritic clots of clinopyroxene ± plagioclase ± biotite. The clinopyroxene phenocrysts are chemically homogeneous, their crystallization temperature is ca. 900 °C representing the crystal mush, whereas the plagioclase and the sanidine crystallized at a lower temperature (ca. 790 °C) representing the rhyolitic lens. Noble gas isotopic composition of the clinopyroxene indicate no mantle-derived fluids (< 0.5%) having an R/Ra of ca. 0.04 Ra. The rejuvenation of the system probably occurred due to implementation of mafic magma at depth leading to a heat transfer and partial melting of the cumulate. This led to crystallization of Ba-rich rims of the sanidine and An- and Sr-rich rims of the plagioclase. The crystal mush zone beneath Šumovit Greben might be connected to the nearby, more mafic volcanic centers, and the eruption of Šumovit Greben could have been the start of the last cycle in the lifetime of the Kožuf-Voras volcanic system.

Seismicity and Fault Interaction in the Gulf of Aqaba

The Gulf of Aqaba is considered one of the most seismotectonically active regions in the Middle East. This study analyzes the seismic activity from 1983 to 2018 to investigate the spatio-temporal distribution of the events in the Gulf’s three basins. The seismic activity is characterized by conventional mainshock–aftershock sequences and swarm activity. Most activity is located in the Aragonese basin, while the Dakar basin shows less seismic activity. The b-value was calculated for the three basins from the declustered catalogue, representing the fingerprint of the transform fault. Within the Aragonese, three significant earthquakes occurred in 1993, 1995, and 2015 with moment magnitude (Mw) of 5.8, 7.2, and 5.2, respectively. An intermediate seismic quiescence preceded the three earthquakes. The quiescence time for the 1995 earthquake began at the tail of the aftershocks of the 1993 mainshock, suggesting that the two earthquakes were not entirely independent. At the tail of the 1995 earthquake aftershocks, the seismic activity spread across the Gulf, increasing in frequency and decreasing in magnitude. A similar pattern was observed for the seismic quiescence preceding the 2015 mainshock. The occurrence of the three significant and proximal earthquakes in the Aragonese region over a 22-year interval, with the described similarities, suggests a link between these earthquakes. Finally, the Coulomb stress transfer shows that the 1993 source fault seems to increase the stress loading on the 1995 left-lateral strike-slip fault, and the latter would also increase the stress transfer on the 2015 left-lateral strike-slip fault.

Effects of Tectonic Quiescence Between Orogeny and Rifting

AbstractTectonic quiescence is a period of nearly null relative plate motion. During the Atlantic Ocean opening, rifting cut across continental segments of supercontinent Pangea that had been through different periods of quiescence, which varied from tens to hundreds of Myr. Using numerical models, we explored the effects of quiescence between orogeny and rifting on the pre‐rift lithosphere and subsequent conjugate rifted margin configuration. Our model results showed that quiescence of ∼30–60 Myr caused wide orogenic wedges (&gt;300 km) to be heated beneath their centers, which led to the breakup of the lithospheric mantle before the breakup of the continental crust during rifting, resulting in hyperextended conjugate rifted margins. In these scenarios, continental lithosphere breakup away from the suture contributed to the preservation of previously subducted lower crust along the subduction zone. Long periods of tectonic quiescence (∼100 Myr) experienced by a wide orogen permitted efficient orogenic collapse and lateral spreading, with pronounced lithospheric thermal weakening. Consequently, post‐quiescence rifting reactivated the suture and effectively drove plate eduction, exhuming most of the subducted continental lower crust and mantle lithosphere. Ultimately, ultra‐wide domains developed into asymmetric conjugate margins. Contrastingly, in narrow orogenic wedges (&lt;200 km), different quiescence durations had minor effects on the margin architecture. In these cases, a longer quiescence time contributed to a larger preservation of subducted crust in the fossil subduction zone after rifting. Our models agree with conjugate rifted margins in the North and South Atlantic, which probably developed after the collapse of wide orogens and subsequent periods of tectonic quiescence.

Comparing the effectiveness of two different dosage regimes of oral nifedipine in the treatment of preterm labour

Objective: To compare the effectiveness and side effect of two different dosage regimes of oral Nifedipine in the treatment of preterm labour Methods: A double blinded randomized controlled trial in which 86 pregnant women with preterm labour were randomized to receive either the low or high dose regimen of Nifedipine for tocolysis. Low dose of 10 mg of oral Nifedipine then 5mg every 15min for 1hr 10mg 6hly for 48hrs, while the high dose was 20 mg of oral Nifedipine followed by 10 mg every 15 minutes for 1hr then 20mg 6hourly for 48 hours. The primary outcome was defined by mean uterine quiescence time and fetomaternal side effect were compared between the groups. Results: The mean uterine quiescence time for the low dose and high dose regime were comparable 13.60±11.69 hours versus 12.16±8.90 hours (P = 0.747) respectively, there was no statistical significance difference. None of the patients in both groups needed rescue treatment. Forty patients (93%) versus 41 patients (95%) (P = 0.506) of low and high dose respectively where able to achieve uterine quiescence within 48hours, there was no statistical significant difference. Maternal headache was higher in the high dose compared to the low dose but not statistically significant {19% vs 5% (p = 0.08)} None of the women in both groups had fetal heart rate abnormality. Discussion: The high dose regimen of oral Nifedipine for tocolysis does not have any advantage over the low dose regime in terms of effectiveness for tocolysis and infact low dose had a lower maternal side effect.

The Relation between Outburst Rate and Orbital Period in Low-mass X-Ray Binary Transients

Abstract We have investigated the outburst properties of low-mass X-ray binary transients (LMXBTs) based on a comprehensive study of the outbursts observed in the past few decades. The outburst rates were estimated based on the X-ray monitoring data from Swift/BAT, RXTE/ASM, and MAXI and previous reports in the literature. We found that almost all LMXBTs with the orbital period below ∼12 hr showed only one outburst in these observations. There are systematic differences in the outburst rate between long-period ( hr) and short-period ( hr) systems. We infer that mass transfer rate is responsible for the systematic difference, since the disk instability model suggested that the mass transfer rate is a key factor affecting the quiescence time. The difference in outburst rate between long-period and short-period LMXBTs is probably due to the different mass transfer mechanism at different evolutionary stages of the donors. Based on the evolutionary tracks of single stars, we derived the critical orbital period for X-ray binaries that harbor a subgiant donor in various metallicities. The critical orbital period ( hr) is consistent with the above orbital period boundary obtained from the statistics of outburst rates. Furthermore, we found a negative correlation between the outburst rate and the orbital period in the samples for which the luminosity class of the donor star is III/IV. The best-fitting power-law index for the black hole subsamples is roughly consistent with the theoretical prediction for those systems with a donor star evolved off the main sequence.

Quiescence in Aedes aegypti: Interpopulation Differences Contribute to Population Dynamics and Vectorial Capacity.

The strategy of Aedes aegypti to prolong embryonic viability by quiescence has severe implications for geographic expansion and maintenance of mosquito populations in areas under control measures. We evaluated the effects of quiescence on biological parameters directly or indirectly associated with population dynamics and vectorial capacity in populations of this mosquito species from two Brazilian municipalities characterized as dengue, chikungunya, and Zika transmission areas. Egg viability, initial hatching time, post-embryonic development time, adult emergence rate, sexual proportion, adult size, fecundity, and fertility were analyzed using eggs stored for 10, 40, 70, 100, 130, and 160 d. Quiescence time reduced overall egg viability and post-embryonic development time in both municipalities but was more costly in Aracaju (100 d, 8 d) than in Recife (130 d, 7.5 d). Emergence rates increased in Recife when the eggs were older, but not in Aracaju. Significant deviations in sexual proportion, with male predominance, were observed in both populations. Initial hatch, fecundity, fertility, and adult size did not significantly influence egg quiescence time. These results indicate intrinsic and differential characteristics for each A. aegypti population, suggesting a differential cost of quiescence for population dynamics parameters that can indirectly affect vectorial capacity and control measures.

Trade-off results for connection management

A connection management protocol establishes and handles a connection between two hosts across a wide-area network to allow reliable message delivery. We continue the previous work of Kleinberg et al. (Proceedings of the 3rd Israel Symposium on the Theory of Computing and Systems, January (1995), pp. 258–267) to study the precise impact of the level of synchrony provided by the processors’ clocks on the performance of connection management protocols, under common assumptions on the pattern of failures of the network and the host nodes. Two basic timing models are assumed: clocks that exhibit a certain kind of a drift from the rate of real time, and clocks that display a pattern of synchronization to real time. We consider networks that can duplicate and reorder messages, and nodes that can crash. We are interested in simultaneously optimizing the following performance parameters: the message delivery time, which is the time required to deliver a message, and the quiescence time, which is the time that elapses between periods of quiescence, in which the receiving host deletes all earlier connection records and returns to an initial state. We establish natural trade-offs between message delivery time and quiescence time, in the form of tight lower and upper bounds, for each combination of the timing models and failure types. Several of our trade-off results significantly improve upon or extend previous ones shown by Kleinberg et al.

Universal dynamic synchronous self-stabilization

We prove the existence of a "universal" synchronous self-stabilizing protocol, that is, a protocol that allows a distributed system to stabilize to a desired nonreactive behaviour (as long as a protocol stabilizing to that behaviour exists). Previous proposals required drastic increases in asymmetry and knowledge to work, whereas our protocol does not use any additional knowledge, and does not require more symmetry-breaking conditions than available; thus, it is also stabilizing with respect to dynamic changes in the topology. We prove an optimal quiescence time n+D for a synchronous network of n processors and diameter D; the protocol can be made finite state with a negligible loss in quiescence time. Moreover, an optimal D + 1 protocol is given for the case of unique identifiers. As a consequence, we provide an effective proof technique that allows to show whether self-stabilization to a certain behaviour is possible under a wide range of models.

Solid Freeforming of Silicon Carbide by Inkjet Printing Using a Polymeric Precursor

Preceramic polymers can be dissolved in solvents to form low‐viscosity fluids. This makes them suitable for solid freeforming by direct inkjet printing. Two ways of using polycarbosilane (pcs) were investigated. In the first, it was dissolved in n‐heptane at up to 30 vol% and printed as a single‐phase material. In the second, it was used as an organic binder for silicon carbide powder suspended in an homologous series of hydrocarbon solvents ranging from n‐heptane to n‐decane. Polyisobutene succinimide was used as a surfactant. In both cases, components could be rendered successfully but pyrolysis of the unfilled pcs resulted in cracking. Components printed with powder suspensions did not crack on pyrolysis, retained overall near net shape, and underwent low shrinkage (8.2 vol%). The molecular weight of the n‐paraffin solvents influenced the viscosity and hence the maximum powder loading while the volatility, a property also related to molecular weight, influenced the quiescence time and the drying time needed between layers. Octane gave the best compromise between speed of printing, the quality and knitting of droplet relics, and the avoidance of nozzle blockage caused by too rapid drying.

Stabilizing time-adaptive protocols

We study the scenario where a transient batch of faults hits a minority of the nodes in a distributed system by corrupting their state. We concentrate on the basic persistent bit problem, where the system is required to maintain a 0 1 value in the face of transient failures by means of replication. We give an algorithm to stabilize the value to a correct state quickly; that is, denoting the unknown number of faulty nodes by f, our algorithm recovers the value of the bit at all nodes in O( f) time units for any f < n 2 , where n is the number of all nodes. Moreover, complete state quiescence occurs in O( diam) time units, where diam denotes the actual diameter of the network. This means that the value persists indefinitely so long as any f < n 2 faults are followed by Ω( diam) fault-free time units. (Strict self-stabilization requires recovery for f ⩾ n 2 as well.) We prove matching lower bounds on both the output stabilization time and the state quiescence time. Using our persistent bit algorithm, we present a transformer which takes a distributed non-reactive non-stabilizing protocol P , and produces a protocol P 1 which solves the problem P solves, with the additional property that if a batch of faults changes the state of f < n 2 of the nodes, then the output is recovered in O( f) time units, and the state stabilizes in O( diam) time units. Our upper and lower bounds are all proved in the synchronous network model.

Direct determination of cobalt in unpurged oceanic seawater by high speed adsorptive cathodic stripping voltammetry

A fast, sensitive method to determine Co (II) in unpurged ocean seawater is presented. The method combines high scan speed staircase voltammetry (HSACSV) and nitrite catalytic effect to enhance Co(II)-dimethylglyoxime reduction currents. The catalytic effect was magnified using high speed adsorptive cathodic stripping voltammetry and peak currents of ca. 0.1 μA were obtained for pM cobalt samples using 30-s deposition times. The effect of buffer, pH, nitrite concentration and scan speed on cobalt sensitivity was studied. Capacitance currents developed at high scan speeds were filtered by background subtraction. The same procedure was successfully applied to remove oxygen interference in unpurged solutions. Blank voltammograms were obtained in different ways yielding similar results without variation in peak reproducibility or accuracy. Nickel and zinc interferences were removed using a cleaning potential before the scan at −1.03 V. Ratios over 10 000 fold were eliminated using more negative cleaning potential steps. Nickel can also be measured by this method. Total analysis time of unpurged seawater (pM levels of cobalt) was decreased to reagents addition time, 30-s adsorption period and 10-s quiescence time. A detection limit of 5.9 pM Co was achieved in seawater. Short analysis time, sensitivity and portable hardware recommend this method for aboard determinations of cobalt. An oceanic profile of cobalt was measured at the Central East Atlantic Ocean.

Influence of growth rate retardation on time budgets and energetics of Arctic Tern Sterna paradisaea and Common Tern S. hirundo chicks

Time budgets of free‐living chicks of Arctic Terns Sterna paradisaea and Common Terns S. hirundo throughout development are presented with special reference to changes in time allocation when growth rate varies. Chicks of both species were inactive most of the time observed (87%). Time allocated to the different behaviours changed during development and was generally better correlated with body mass than age. Slower growing nestlings were brooded more and allocated more time to quiescence and less time to locomotion, preening, begging and attacking (the latter two significant only for the Arctic Tern). The energetic implications of variation in time budgets with age and growth rate were considered. Parental brooding resulted in an average energy saving of nearly 40% of an individual nestling's thermoregulatory costs. Whereas thermoregulatory costs remained nearly unchanged in Arctic Tern chicks, these were negatively correlated with growth rate in Common Terns. Tentatively, we estimated a 30% reduction in a nestling's total energy requirement for a 50% reduction in average growth rate for both species.

Rapid adsorptive cathodic stripping voltammetry of zinc complexes in sea water

The effects of the potential scan speed on the adsorptive cathodic stripping voltammetric determination of zinc-tetramethylenedithiocarbamate complexes in sea water were investigated. It was observed that an increase in scan speed increases the peak height and peak width, shifts the peak potential towards negative values and increases the capacitance background current. These effects were explained by taking into account the ohmic drop at high scan speeds. Several advantages of using a high scan speed in the determination of zinc were found. The faradaic current and sensitivity of the determination are noticeably increased as the whole electroactive substance is reduced in a shorter time. The stirring or turbulent motion of the solution during the scan does not perturb the zinc peak as the complete scan is done in a few milliseconds. Oxygen interference is less severe as the metal and oxygen reduction currents are now in the same current range. The entire analysis time can be markedly reduced as the purging, collection and quiescence time can be decreased. The method is proposed for use on-board oceanographic vessels where its advantages are especially valuable. All results were obtained using a laboratory-designed polarograph able to operate at very high scan speeds.

A method to determine the duration of quiescence in a seismic gap

The concept of seismic gap has been developed in recent years to identify areas which have not been active in the past few years and arethereforeconsidered to have potential for large earthquakes in the future. I propose an empirical method to determine the duration of quiescence in seismic gap by estimating slip which will occur when the gap ruptures. This method depends on rate of plate motionlength of seismic gapand empirical relationship between rupture length and seismic moment. For earthquakes which have occurred in previously identified gaps and for which duration of quiescence is knownthis method predicts quiescence time to within about 10 yearswhichconsidering errors in plate motion rateslength of seismic gapand empirical relationship involvedis very good.

Seismic quiescence precursory to a past and a future Kurile island earthquake

A systematic search was made for seismicity rate changes in the segment of the Kurile island arc from 45°N to 53°N by studying the cumulative seismicity of shallow (h = 100 km) earthquakes within 11 overlapping volumes of radius 100 km for the time period 1960 through beginning of 1978. We found that in most parts of this island arc and most of the time the seismicity rate as obtained from the NOAA catalogue and not excluding any events is fairly constant except for increased seismicity in the mid 1960s in the southern portion due to the great 1963 mainshock there, and for seismicity quiescence during part of the time period studied within two well defined sections of the arc. The first of these is a volume of 100 km radius around a 1973 (Ms = 7.3) main-shock within which the seismicity rate was demonstrated at the 99% confidence level to have been lower by 50% during 2100 days (5.75 years) before this mainshock. The second volume of seismic quiescence coincides with the 400 km long north Kuriles gap. In this gap the seismicity rate is shown (at the 99% confidence level) to be lower by 50% from 1967 to present (1978), in comparison with the rate within the gap before 1967, as well as with the rate surrounding the gap. We propose that the anomalously low seismicity rate within the Kuriles gap is a precursor to a great earthquake, the occurrence time of which was estimated by the following preliminary relation between precursory quiescence time and source dimension T — 190L 0,545. We predict that an earthquake with source length of 200–400 km (M > 8) will occur along the north Kurile island arc between latitude 45.5°N and 49.2°N at a time between now and 1994.