Stage Of Eruption Research Articles

Zircon double-dating of Quaternary eruptions on Jeju Island, South Korea

Models of volcanic eruption periodicity are vital for hazard prediction, but require an understanding of the past pattern of melt evolution and transport. Zircon double-dating combines (U-Th)/He methods with U-Pb or U-Th disequilibrium geochronology to determine the timing of volcanic eruptions for rocks with a particular emphasis on those younger than ca. 1 Ma. This paper focuses on the Jeju Island intraplate volcano in South Korea, and compares a previously proposed model for trachyte eruption with new zircon double-dating results.The results document four episodes of trachyte eruption on Jeju. The oldest trachytes were erupted at ca. 750–477 ka, followed by an episode at ca. 97–53 ka. Two further eruptive episodes occurred at ca. 31–23 ka and ca. 2 ka. This ca. 2 ka eruption age is the first geochronological documentation of such young eruptive activity from the island. In addition to the new eruption ages, there is evidence for three separate stages of zircon crystallisation, which are correlated with the three oldest eruption stages. The strong temporal correlation of zircon crystallisation and eruption on Jeju points to a simple magmatic plumbing system. These observations have important implications for hazard monitoring and mitigation on Jeju Island by highlighting the historical trachyte eruptions and the magmatic tempo for this system.

Population Dynamics of the Gypsy Moth in Oak Forests in the Forest Steppes of European Russia

There were five major outbreaks of the gypsy moth (Lymantria dispar L.) population between 1977 and 2018. The representation of the phases combined with the their ecological and population indices made it possible to recognize the eruptive and relatively prodromal cycles in the dynamics. The permanent outbreak was a feature of the coppice oak forests in southeastern Europe. The mean population size of the gypsy moth was higher, the maximum density and range of fluctuations were lower, the minimum density was significantly higher, and long periods of time between the outbreaks were not found under the optimum conditions in degraded forest stands with a simple structure growing in a dry climate. The outbreaks occurred every 10 years, while the population fluctuations could be characterized by cycles of various intensity. An eruptive stage was followed by a less intense outbreak (relatively prodromal stage), which differed from conventional prodromal stage by the recovery of the population at a level above stable, which immediately led to a fast growth and a new outbreak. The reason was the insufficient controls set by the complex of polytrophic entomophags, which held the population of gypsy moths at a low to near-average number.

Above or below 14years? An orthopantomographic study based on chronological course of eruption of mandibular premolars and second molars in a sample of south Indian children.

In the context of dental age assessment, two significant factors can be studied; tooth mineralisation and tooth emergence. Little is known about the role of a second molar eruption in forensic age estimation. This paper aims to contribute to forensic age estimation using an age threshold of 14years, studying the eruption stages of permanent mandibular premolars and second molars. Totally 640 orthopantomograms (OPGs) of south Indian children, aged between 10 and 18years, were evaluated using Olze et al. staging of tooth eruption stages (A-D). Spearman's rho correlation showed a strong, positive, and statistically significant correlation between the chronological age and the eruption stages of both sexes' teeth. Accuracy, sensitivity, specificity, likelihood ratios, and post-test probability values were calculated for all tested teeth. The best performance to discriminate individuals above or below 14years showed stage D in second molars. The sensitivity varied between 89% and 94% and specificity between 75% and 84%, respectively. Receiver operating characteristic curve analysis revealed high diagnostic performance for stage D, with area under the ROC curve (AUC) values of 84% and 85% for tooth 37 and 85% and 83% for tooth 47 in males and females, respectively. In conclusion, it is possible to predict age over 14years in south Indian children using tooth emergence stages from OPGs with a relatively high interobserver agreement and good diagnostic accuracy. However, there are some limitations and, therefore, must be used in conjunction with other methods.

Factors affecting molar size in Sus scrofa

Teeth are thought to be less affected than post-cranial elements by factors such as age, region, sex, and post-Pleistocene climate change, making changes in tooth size a better gage of domestication-induced morphological change in Sus scrofa. Rigorous empirical evaluation of this assumption, however, has been lacking. Here we examine the impact of multiple factors on molar size in an assemblage of modern wild boar from Southwest Asia, as well as a large assemblage of ancient S. scrofa from an archaeological site in southeastern Turkey dated to 11,600 cal. BP. We find that age related interstitial wear has a profound impact on molar lengths. Comparisons of length measurements of S. scrofa molars should only be made if one strictly controls for the state of wear, as well as the stage of crown development and eruption in third molars. Breadth measurements, on the other hand, are little affected by progressive wear and, as a result, are preferable to length measurements in the analysis of molar size in S. scrofa. We also evaluate the impact of logarithm size index (LSI) scaling on molar dimensions. Molar lengths are subject to a number of factors that distort meaningful patterning rendering LSI values of length dimensions of little utility in the evaluation of molar size in S. scrofa. With the exception of the upper first molar, LSI values of molar breadths appear to both capture and amplify patterns seen among unconverted measurements of individual teeth. Our evaluation also confirms the assumption that the size of post-cranial elements is more profoundly affected than molars by factors such as region and Post-Pleistocene climate change. While sexual dimorphism also has a greater impact on the size of post-crania than on molars, the degree of sexual dimorphism in molar breadths, as well as in M3 lengths, is still substantial and must be taken into account in any study of S. scrofa molar size. Before interpreting downward shifts in molar size as an indicator of domestic status, archaeozoologists need to first to consider the possible impact of differences in the proportions of males and females in archaeological assemblages. We conclude with a number of recommendations for new protocols for the analysis of S. scrofa dental metrics. We also offer observations about the impacts of factors like region, sex, and change over time on the size of the molars of this species that may open up new areas of research.

Evolution of the Alu-Dalafilla and Borale volcanoes, Afar, Ethiopia

The Danakil depression marks a progressive change from continental rifting in Afar to seafloor spreading further north in the Red Sea. Extension and volcanism in this incipient spreading centre is localised to the ~70-km-long, 20-km-wide active Erta Ale volcanic segment. Here, we combine remote sensing and major element geochemical analysis to determine the structure and composition of three volcanoes on the Erta Ale Volcanic Segment: the Alu dome, the Dalafilla stratovolcano and the Borale stratovolcano. We investigate the evolution and compositional variation within and between these volcanic complexes. Our results show that most flows are sourced from scoria cones and fissures, representing in total 15 phases of volcanism that occurred within four major eruptive stages, most likely occurring in the last 80 thousand years (kyr). The first stage represents large-scale fissure volcanism, comprising submarine basaltic phases. Stage two involves basaltic fissure volcanism around Alu. The third stage is dominated by trachy-andesite to rhyolitic volcanism from the volcanic edifices of Alu, Dalafilla and Borale and the fourth by a resumption of small-scale basaltic/trachybasalt fissure systems. Geochemical modelling indicates a paucity of crustal assimilation and mixing within the sub-volcanic magmatic system. Spatial analysis of volcanic cones and fissures within the area indicate the presence of a cone sheet and ring faults. The fissures are likely fed by sills connecting the magma source with the volcanic edifices of Alu and Borale. Our results reveal the cyclic nature of both eruption style and composition of major volcanic complexes in rift environments, prior to the onset of seafloor spreading.

Indicators of permanent teeth eruption in children of Tashkent city and comparative assessment with the data of peers of different Russian cities

Relevance. Characteristics of eruption of secondary teeth is of diagnostic and prognostic interest, is the basis for implementation of targeted therapeutic and preventive measures among children. No research has ever been carried out in Uzbekistan to study an age and gender regional features of secondary teeth eruption. The aim is to determine the timing and symmetry of secondary teeth eruption in children of the city of Tashkent of the Republic of Uzbekistan and comparative assessment with the children of different cities of Russia.Materials and methods. 3,834 children between 3 and 17 years were conducted dental examination. A comparative analysis was made of the initial, intermediate and final periods of eruption of secondary teeth for children of Uzbekistan (Tashkent city) and Russia (Saratov, Izhevsk and Sergach).Results. In Tashkent children of both gender, in most cases, lower teeth were erupted before than their antagonists. In girls, teeth were erupted earlier than their male counterparts. At the initial stage of eruption, asymmetry was more pronounced in boys than in girls, while in the middle and final stages it was more pronounced in the opposite direction. Observed asymmetry of antimere’s teeth were indicated left-handed permanent dentition in boys and right-handed in girls. Children of Tashkent city were observed permanent dentition in one group of teeth 1-16 months earlier, and in others – 1-24 months later than their peers in Russian cities. Revealed differences were more pronounced among boys than among girls. Children in Tashkent differed more from their peers in Sergach and less from those in Izhevsk. Conclusions. Regional peculiarities of permanent dentition in children of Tashkent city and revealed expressed differences with indicators of Russian children are the basis for development of separate age and gender normative assessment permanent dentition tables for children of Uzbekistan.

Age‐related changes in oral motor‐control strategies during unpredictable load demands in humans

To investigate age-related changes in oral motor strategies in response to unpredictable load demands. Sixty-five healthy children (aged 3-17yr) were divided into five age-groups based on their dental eruption stages and compared with a group of healthy adults (aged 18-35yr). Each participant was asked to perform a standardized motor control task involving 'pulling' and 'holding' a force transducer with the anterior teeth. Different loads were attached to the force transducer in an unpredictable manner. The temporal force profile was divided into two time-segments (an initial segment and a later segment). The peak force and peak force rate during the initial time-segment, and the holding force and intra-trial variability (coefficient of variation) during the later time-segment, were measured. The results showed no differences in the peak force, peak force rate, holding force, and force variability in children compared with adults. However, the trends in the data evaluated using a segmented regression analysis showed that a breakpoint (abrupt change) consistently occurred in the late-mixed dentition group (age 9-11yr) for most of the outcome variables. The results indicate that while the motor control strategies in children appear to be similar to those in adults, there is a shift in the oral motor developmental trend during the late-mixed dentition stage.

Isolated alkaline basalt occurrences in the northern Spessart, Germany: Outposts of the Early Miocene Vogelsberg shield volcano?

Four isolated occurrences of Tertiary volcanic rocks in the northern Spessart at Beilstein, Hoher Berg, Madstein and Kasselgrund are relics of volcanic vents or dikes. They display alkaline basalts (s. l.) with mainly trachybasaltic composition, which, from normative mineral contents, may be designated as nepheline-bearing alkali-olivine basalts and basanites. In part, centimetre-sized xenoliths of spinel lherzolite occur. According to Ar-Ar dating, the alkaline basalts (s. l.) from Kasselgrund have erupted at 18.1 ± 0.3 or 19.3 ± 0.4 Ma, those of Hoher Berg between c. 18 and c. 21 Ma. These ages correspond to the Vogelsberg eruption stage I. A slightly younger Ar-Ar age of 16.8 ± 0.3 Ma was recorded for the Beilstein basalt, which is in chronological accordance to the turn of Vogelsberg eruption stages II and III. Samples of all four occurrences reveal major and trace element compositions, which are different from those of the Vogelsberg basalts. Compositions of basalts of the stage III from Vogelsberg coincide most with the Spessart basalts. This signals a special position of the northern Spessart volcanic rocks either as a discrete spatial part of the Vogelsberg volcanic suite or as smaller, independent eruption centres.

Depth of Gingival Sulcus in Healthy Children with Erupting Permanent Teeth.

Measuring the gingival sulcus depth in children while their permanent teeth erupt is rather difficult especially if using reference norms for adults for a base. Assessment of the depth of the gingival sulcus during the period of tooth eruption in healthy children. Thirty children were included in the study (age range 6 - 14 yrs). The children had good oral hygiene and no history of systemic disease. They were clinically examined - their dental statuses were taken, stages of permanent teeth eruption (up to 1/3 of the clinical crown, between 1/3 and 2/3, over 2/3, in occlusion contact), and their gingival sulcus depth was measured at 6 distovestibular, vestibular, mesiovestibular, mesiolingual, lingual, and distolingual sites using an electronic probe Parometer (Orange). It was concluded that the one with the highest value would be considered the maximum depth of the sulcus. The gingival sulcus depth in fully erupted teeth is very similar to that in healthy adults (2.20 - 0.49 mm). The change of sulcus depth in incisors and canines has a variation of 1.5 mm, which at the end of eruption is close to those in adults. Maximum sulcus depth for molars, premolars and incisors was measured distovestibularly, and for canines - mesiovestibularly. At the various stages of eruption, the depth of the gingival sulcus plausibly decreases in all tooth types, and by the end of eruption it reaches a depth similar to that of the adult standard. Most indicative in regard to depth are the vestibular probing point.

Effect of food hardness on chewing behavior in children

ObjectiveTo investigate the effects of food hardness on chewing behavior in children compared with adults.Materials and methodsHealthy children (3–17 years) were equally divided into five groups based on their dental eruption stages. Each participant ate soft and hard viscoelastic test food models (3 each), while the three-dimensional jaw movements and electromyographic (EMG) activity of the bilateral masseter muscles were recorded. The data from the children were compared with a control group of healthy adults (18–35 years). The data were analyzed with nonparametric tests.ResultsThere was no significant difference in the number of chewing cycles and the duration of the chewing sequence between children groups and adults. Children with primary dentition (3–5 years) showed shorter lateral jaw movement and higher muscle activity at the end of the chewing sequence, compared with adults. Further, children’s age-groups (3–14 years) failed to adapt their jaw muscle activity to food hardness. However, at the late-permanent dentition stage (15–17 years), children were capable of performing adult-like chewing behavior.ConclusionsOverall, it seems that children as young as 3-year-old are quite competent in performing basic chewing function similar to adults. Yet, there are differences in the anticipation or adaption of jaw muscle activity and jaw kinematics to food hardness.Clinical relevanceThe study may have clinical implication in the diagnosis and management of children with chewing impairment associated with dental malocclusions and other orofacial dysfunctions.

Transition from passive to pre-extrusion degassing of ascending andesitic magma before the lava dome-building eruption as derived from the seismic signals and tilt changes: Volcán de Colima, México, August–September 2004

Volcanoes emit volcanic gas during various types of activity. In the case of andesitic and dacitic volcanoes the high viscosity of silicic magma inhibits the release of volatiles. This increases the possibility that gas escape will occur explosively. The explosive emission of volatile constituents, presented in magmas, generates the seismic signals which may give information about the process of degassing at different stages of eruption. Transition between the eruptive episodes of lava dome-building at andesitic volcanoes represents the transition from passive degassing of the final stage of one episode to pre-extrusion degassing of the next episode. In this article we use the seismic parameters of volcanic explosions, volcanic tremor and micro-explosions, recorded at Volcán de Colima during August–September 2004, to describe the process of transition from passive to pre-extrusion degassing from episode 2 (May 2001–September 2004) to episode 3 (30 September 2004–January 2007). Variations in the tilt changes allowed us to identify three periods in development of this transition: period of passive degassing at the final stage of episode 2 (until 6 September) and two periods of pre-extrusive degassing at the initial stage of episode 3 defined by processes of inflation and deflation of volcanic structure from 6 to 30 September. Intensity of degassing of magma, expressed in the energy of volcanic explosions, decreased during transition from passive to pre-extrusive stages. During pre-extrusion periods of inflation and deflation of volcanic structure the depths of explosive events became shallower. Period of deflation was characterized also by a dominance of degassing processes occurring within the permeable cap of ascending magma and generating volcanic tremors and swarms of micro-earthquakes. Comparison of degassing of magma during pre-extrusive period and co-extrusive and post-extrusive periods showed the similarity in intensity of degassing of magma during the pre-extrusive and co-extrusive periods but a sharp increase in degassing intensity during the post-extrusive period of lava dome destruction with large explosions. It was shown also minor intensity of degassing processes just preceding the beginning of the lava dome building comparing with intensity of degassing processes just preceding the beginning of the lava dome destruction with great explosions.

Date of death of domestic caprines assessed by oxygen isotopic analysis of developing molars: Implications for deciphering the calendar of pastoral activities in prehistory

The assessment of the date of death (DOD) of animals found in archaeological sites provides insights into the exploitation of their environment by ancient mobile and sedentary populations. In an attempt to overcome the limitations of the traditional methods, we determine the DOD of domestic caprines using sequential oxygen isotope analysis of developing tooth enamel. We built a reference set composed of developing molars from 14 modern sheep and goats from Western and Central Mongolia with known DOD. The teeth were sequentially sampled, and δ18O sequences were modelled using a cosine function in order to position the lowermost δ18O value (δf) within the annual cycle. We found that δf values are strongly linearly correlated with the DOD (R2 = 0.88), allowing the use of this regression to estimate the DOD with a precision of about ±25 d (1σ). This method was applied to determine the DOD of caprines found in two graves in the Xiongnu necropolis of Egiin Gol, Mongolia. We determined a slaughter date of late July and late September for the two graves, respectively, suggesting that burial occurred during the warm season. By combining this information with age at death assessed using tooth eruption stages and tooth wear patterns, we were also able to determine that caprine birth occurred mostly in April and was strongly controlled within this seasonal window by the herders, much like in Mongolia today.

Eruption Guidance of Horizontally Impacted Permanent First Molar with Primary Retention of Primary Second Molars: Case Reports

Tooth eruption involves a complex developmental process of tooth migration from the dental follicular origin to the final occlusion position in the oral cavity via the alveolar process. Disturbance of tooth eruption can occur at any point in a series of eruption stages; however, horizontal impaction of the mandibular first molar and primary retention of the primary mandibular second molar are rarely observed simultaneously. This study describes the treatment for two cases of horizontally impacted first molar with primary retention of primary molar. The primary retention of the primary mandibular second molar was extracted, and orthodontic traction was applied to the horizontally impacted primary mandibular first molar. Subsequently, displacement of the premolar tooth bud was improved and space regaining for eruption was achieved, guiding to normal eruption of the first molar.

Quaternary ring plain- and valley-confined pyroclastic deposits of Aragats stratovolcano (Lesser Caucasus): Lithofacies, geochronology and eruption history

Aragats stratovolcano, located on the South Armenian block, a micro-plate in the Arabian-Eurasian collision zone, has a complex and long-lasting Quaternary eruption history. Cataclysmic eruptions formed widespread pyroclastic deposits, which are interrupted by numerous basaltic to trachytic lava flows as well as lacustrine and lacustrine-alluvial sediments. Contrary to previous concepts, detailed mapping of lithofacies variation combined with stratigraphic documentation and new high-precision 40Ar/39Ar ages revealed four eruption cycles, each started with mafic lavas and generally finalized with pyroclastic deposits. These data contributed to a fundamental reinterpretation of the development of the Aragats Volcanic Province (AVP). Within an estimated activity of one million years, Aragats itself experienced three eruption stages, two of which culminated in pyroclastic deposits of remarkable lithofacies variability with ages of 0.97 to 0.90 Ma and 0.75 to 0.65 Ma, respectively. Vertical and lateral changes in proximal and distal facies distribution of pyroclastic flow deposits indicate temporal variations in eruption intensity and periods of relative volcanic quiescence.Aragats' explosive activities were dominated by Plinian eruptions with columns as high as 25 km, while others are characterized by low eruption columns followed by instantaneous collapse, in one case associated with vent widening, possible caldera collapse and breccia formation. Furthermore, one AVP unit features juvenile lapilli and blocks including banded and armored pumice, indicating magma mingling and their involvement in the erupting mixture before magma fragmentation.

Numerical investigation on the mechanism of geyser in cryogenic fluid pipes

In order to study the mechanism of geyser in cryogenic fuel system, a CFD model based on VOF method for two-phase heat and mass transfer process is established and validated. The detailed transient behavior and the whole formation process of geyser in a cryogenic pipe are successfully captured and predicted. The prediction performance of 3-D, 2-D axisymmetric and 2-D planar model is evaluated. The formation and development of the whole geyser process are clearly revealed by visualization and macroscopic parameter analysis, and a contrastive study is performed to investigate the mechanism of the pressure peak in a geyser. It is found that: The incubation stage occupies the largest portion of geyser period up to 95% in the presented condition and there is a dramatic pressure fall in the eruption stage and a pressure spike in the refilling stage, which leads to a periodic shock of pressure. The violent depressurization boiling is the main cause of the eruption. Moreover, the water hammer induced by vapor condensation will bring about a huge pressure increase, and it becomes the main mechanism for the pressure spike in the refilling stage.

Using a Gaussian mathematical model to define eruptive stages of young volcanic rocks in Tengchong based on laser 40Ar/39Ar dating

Reconstruction of Quaternary environments, late Cenozoic geodynamics and evaluation of volcanic hazards, all depend on the precise delineation of eruptive stages. In recent years, laser 40Ar/39Ar dating methods have been widely used for dating young volcanic rocks, given their stable automated testing process, very low background level and high sensitivity, which meet the requirements for precise dating of young samples. This paper applied high-precision laser 40Ar/39Ar dating to the main volcanic units in the Tengchong area and obtained ages in the range of 0.025–5.1 Ma using conventional data processing methods. However, conventional dating highlighted issues related to very low radiogenic 40Ar content, accidental errors and poor data stability, which led to huge age deviations. Moreover, lacking a unified timescale, conventional methods were unable to strictly define the stages of the Tengchong volcanic eruptions, leading to ongoing controversy. In this study, we applied a Gaussian mathematical model to deal with all 378 original ages from 13 samples. An apparent age-probability diagram, consisting of three independent waveforms, have been obtained. The corresponding isochron ages of these three waveforms suggest there were three volcanic eruptive stages, namely during the Pliocene (3.78±0.04 Ma), early Middle Pleistocene (0.63 ±0.03 Ma) and late Middle Pleistocene to early Late Pleistocene (0.139±0.005 Ma). These results accurately define eruptive stages in the Tengchong area.

Age estimation of Brazilian individuals using the London Atlas

ObjectiveThe objective of the present study was to evaluate, for the first time, the applicability of the London Atlas method for age estimation on a sample of Brazilian population. DesignThe study consisted of archived dental panoramic radiographs (n = 288) of individuals aged between 5 and 23 years. Radiographs were assessed using the London Atlas method to determine the developmental and eruption stages of all teeth on each sides of each jaw separately, and also to make an age estimation. ResultsThere was no significant differences between the right and left sides of the jaws (p = 0.31 for males and p = 0.65 for females). An overestimation of age occurred more likely in the female sample when compared to the male sample. Three age groups, 20.5, 18.5 and 19.5 years, presented the highest values ​​of mean absolute difference found in the whole sample. ConclusionThe London Atlas of age estimation performed well in general and good viability in an expert context, with most age groups showing age differences lower than two years of age, however it is necessary that it be applied with caution in certain age groups, especially when the third molar is used as a decision tooth for age estimation. Therefore, it is recommended to use more than one method for assessing the age in those age groups.

Core Matrisome Protein Signature During Periodontal Ligament Maturation From Pre-occlusal Eruption to Occlusal Function.

The pre-occlusal eruption brings the molars into functional occlusion and initiates tensional strains during mastication. We hypothesized that upon establishment of occlusal contact, the periodontal ligament (PDL) undergoes cell and extracellular matrix maturation to adapt to this mechanical function. The PDL of 12 Wistar male rats were laser microdissected to observe the proteomic changes between stages of pre-occlusal eruption, initial occlusal contact and 1-week after occlusion. The proteome was screened by mass spectrometry and confirmed by immunofluorescence. The PDL underwent maturation upon establishment of occlusion. Downregulation of alpha-fetoprotein stem cell marker and protein synthesis markers indicate cell differentiation. Upregulated proteins were components of the extracellular matrix (ECM) and were characterized with the matrisome project database. In particular, periostin, a major protein of the PDL, was induced following occlusal contact and localized around collagen α-1 (III) bundles. This co-localization coincided with organization of collagen fibers in direction of the occlusal forces. Establishment of occlusion coincides with cellular differentiation and the maturation of the PDL. Co-localization of periostin and collagen with subsequent fiber organization may help counteract tensional forces and reinforce the ECM structure. This may be a key mechanism of the PDL to adapt to occlusal forces and maintain structural integrity.

In situ observation of the percolation threshold in multiphase magma analogues

Magmas vesiculate during ascent, producing complex interconnected pore networks, which can act as outgassing pathways and then deflate or compact to volcanic plugs. Similarly, in-conduit fragmentation events during dome-forming eruptions create open systems transiently, before welding causes pore sealing. The percolation threshold is the first-order transition between closed- and open-system degassing dynamics. Here, we use time-resolved, synchrotron-source X-ray tomography to image synthetic magmas that go through cycles of opening and closing, to constrain the percolation threshold ΦC at a range of melt crystallinity, viscosity and overpressure pertinent to shallow magma ascent. During vesiculation, we observed different percolative regimes for the same initial bulk crystallinity depending on melt viscosity and gas overpressure. At high viscosity (> 106 Pa s) and high overpressure (~ 1–4 MPa), we found that a brittle-viscous regime dominates in which brittle rupture allows system-spanning coalescence at a low percolation threshold (ΦC~0.17) via the formation of fracture-like bubble chains. Percolation was followed by outgassing and bubble collapse causing densification and isolation of the bubble network, resulting in a hysteresis in the evolution of connectivity with porosity. At low melt viscosity and overpressure, we observed a viscous regime with much higher percolation threshold (ΦC > 0.37) due to spherical bubble growth and lower degree of crystal connection. Finally, our results also show that sintering of crystal-free and crystal-bearing magma analogues is characterised by low percolation thresholds (ΦC = 0.04 – 0.10). We conclude that the presence of crystals lowers the percolation threshold during vesiculation and may promote outgassing in shallow, crystal-rich magma at initial stages of Vulcanian and Strombolian eruptions.

Developmental and age-related changes in sensorimotor regulation of biting maneuvers in humans

Previous studies indicated distinct differences in biting and chewing behaviors between children and adults. However, these studies used different methodologies and failed to study age-related changes in the fine motor control of biting from childhood to adulthood. Therefore, this study aimed to investigate age-related changes in oral fine motor control in healthy children in comparison to adults. Sixty-five healthy children (3–17 years) were equally divided into five age-groups based on their dental eruption stages. Each participant was asked to hold half a peanut rested on a force transducer between two opposing anterior teeth for 3–4 s before splitting it. The force applied on the transducer was continuously monitored and recorded during food holding and splitting. The data obtained from the children subgroups were compared to an adult group (18–35 years). Results showed that the force regulation during food manipulation was higher and more variable in children with primary to early-permanent dentition stages compared to adults. Additionally, children with primary and early-mixed dentition showed longer food splitting duration than adults and exhibited a predominantly step-wise ramp-increase of force. The results of the present study showed age-related changes in fine motor control of food biting maneuvers. The results of the study also suggested that younger children with primary dentition show signs of immature oral fine motor control. However, with an increase in age and the accompanying structural changes, the oral fine motor control eventually transits to a more matured “adult-like” biting maneuvers.