Time Of Eruption Research Articles

Orthodontic treatment of a severe combined anterior and posterior open bite case, involving ankylosis and eruption disturbances in late adolescence

Treatment of a combined anterior and posterior open bite case is a demanding orthodontic procedure that requires, in many cases, a multidisciplinary approach. Disturbances in the time or pattern of permanent teeth eruption can often cause or aggravate these clinical conditions, that once established can affect the occlusion, the mastication, the speech, and the oral health quality of life index of such a patient. This article describes the orthodontic treatment of a teenager with severe anterior and posterior open bite, a unilateral posterior crossbite and serious mastication problems. Proper diagnosis, treatment planning, and mechanotherapy used, resulted in excellent orthodontic outcome, greatly improving all aspects of the patient’s initial concerns and the clinician’s goals.

Timing, magnitude and geochemistry of major Southeast Asian volcanic eruptions: identifying tephrochronologic markers

ABSTRACTWe review the current knowledge about Southeast Asian volcanoes and their eruption histories, and focus on identifying tephrochronologic markers representing major explosive eruptions in order to further future palaeoclimate and volcanological studies. Forty‐one volcanic edifices in Southeast Asia have been classified as large calderas by Whelleyet al. (2015) and thus have, or are likely to have, produced large explosive eruptions with a Volcanic Explosivity Index (VEI) of 6–8. Unfortunately, only 20 such eruptions have known ages, spanning from 1.2 Ma to 1991ad, and fewer have geochemical data that can be used for tephrostratigraphic correlations. Volcanic products from different geodynamic regions and different sources can generally be distinguished on major element plots (e.g. K2O versus CaO) of matrix glass composition. However, the distinction of multiple eruptions from the same source often requires additional data such as trace element compositions of matrix glass and/or mineral compositions. Biotite, but also magnetite compositions (MgO and TiO2content in particular) appear to be very discriminating. Up to nine tuffs in addition to the three to four Toba tuffs can be utilised as widespread tephrochronologic markers and span a range from 1.2 to 1.6 Ma to recent. As only a few Holocene major eruptions have been well characterised and dated, many large calderas are still unstudied, and many distal tephra layers are still lacking a source, more tephrochronologic markers can certainly be defined in the future.

CONSERVATIVE APPROACH OF DENTIGEROUS CYST WITH ERUPTION OF CYST-ASSOCIATED TEETH: A CASE SERIES

To present a series of clinical cases of dentigerous cysts treated by means of marsupialization using the retained teeth associated with the lesion. This is an epidemiologic study based on the retrospective and descriptive analysis from November 2005 to November 2015. Twelve patients were included in the study, with mean age of 9 years. Eight patients were men and 4 were women. The most involved teeth were premolars and maxillary central incisors and the mean eruption time was 13 months. In all cases there was eruption of the associated tooth and new bone formation in the area where the cyst was present. No recurrences were observed. In the cases treated in the evaluated period, marsupialization was shown as an effective therapeutic option in the approach of young patients.

Is There an Influence of the Pole Tide on Volcanism? Insights From Mount Etna Recent Activity

AbstractWe investigate a possible link between polar motion and (i) seismic energy release and (ii) timing and intensity of eruptions at Mount Etna (Italy) for which a dense observational database is available. Our study suggests that the seismicity around Mount Etna increases during the largest excursions of the Earth rotation pole, which result from the constructive interference of the climate‐driven seasonal and Chandler wobbles. To a lesser extent, a similar link is detected between the pole tide and the erupted volume of magma. We infer that, by creating periodic changes in the state of stress in the crust through a variable centrifugal force and a periodic vertical displacement (pole tide), variations in polar motion influence eruption timing and magnitude and the rate of seismic energy release from volcanoes. This study provides new evidences on the sensitivity of volcanoes to external forcing.

Chronology and sequence of deciduous teeth eruption in children with microcephaly associated to the Zika virus.

Deciduous teeth eruption is connected to children's growth and development. In Brazil, with the increase in the occurrence of children born with microcephaly associated to exposure to Zika virus, studies about orofacial alterations were necessary. Describe the chronology and sequence of deciduous teeth in children with microcephaly due to the fetal exposure to Zika virus. A cross-sectional study involving 74 children of a neuropediatric reference unit in Salvador, Bahia, in 2017 was conducted. Through use of secondary data, interviews with mothers and children's exam, the population was characterized, the chronology and sequence of deciduous teeth eruption was registered, and the analysis of the variables was proceeded. The first eruption happened between 4 and 17 months of age and 52.70% had a delay in the eruption of incisors. The average eruption time for the maxilla varies from 17.92 (16.56-19.28; 95% CI) to 20.43 (19.35-21.51; 95% CI) months, and the jaw from 11.57 (6.85-18.99; 95% CI) to 20.20 (19.09-21.31; 95% CI) months. In 77.94% of population, the eruption of the first teeth was in the lower arch and in 33.82%, molars and/or canines erupted before the incisors. There were alteration in the chronology and sequence of deciduous teeth eruption.

Unravelling the links between seismo-acoustic signals and eruptive parameters: Etna lava fountain case study

Deriving eruption source parameters from geophysical data is critical for volcano hazard mitigation, yet remains a challenging task in most volcanoes worldwide. In this work, we explored the temporal relationship between geophysical signals and eruptive parameters measured during six explosive episodes from the New South-East Crater of Mt. Etna (Italy). The quadratic reduced seismic velocity and pressure were calculated to track the temporal variation of volcanic elastic radiation, and the lava fountain height was estimated by thermal camera image processing. The temporal relationships between these geophysical and eruptive time series were studied. In particular, the first considered lava fountain exhibited a “clockwise hysteresis” pattern: higher seismic amplitude with respect to the fountain height during the waxing phase as compared to the waning phase. We also calculated the regression parameters for both linear and power laws, linking seismo-acoustic and eruptive time series. For the linear regressions, we found fairly constant values of the scaling factors in five out of six eruptive episodes, which can be considered as a promising step to derive eruption source parameters from geophysical data in real-time. Regarding power law regressions, a clear relationship was observed between the exponents determined for the power law linking quadratic reduced velocity and lava fountain height, and the time interval duration from the previous eruption. These results suggest that the condition of the uppermost part of the plumbing system (e.g. viscosity of residing magma and conduit conditions) play a key role in the seismic energy generation during the eruptions.

Statistical analysis of crystal populations and links to volcano deformation for more robust estimates of magma replenishment volumes

Abstract Forecasting the timing and size of volcanic eruptions requires a proper interpretation of multiparametric monitoring signals. Studies of the erupted rocks can provide critical information on the processes and volcano plumbing system that is needed to decode the monitoring signals. Here we present the results of a petrological study of plagioclase phenocrysts using a new statistical approach that allows us to estimate the amount of intruded magma before eruption. Our crystal population analysis of the 2006 and 2010 CE Merapi volcano (Indonesia) eruptions shows that ∼60 ± 20 vol% of the 2010 magma was left over from the 2006 magma, and thus ∼40 ± 20 vol% was newly intruded magma. Using the published values of the 2010 erupted magma volume, this corresponds to >8 to 20 (±7) × 106 m3 of new magma. This is a minimum estimate and is similar to the inferred pre-eruptive deformation volume (18 ×106 m3), although given the uncertainties, several million cubic meters of magma intruded in 2010 could still be in the Merapi plumbing system. Our approach could be used at other volcanoes to quantify the volume of intruded magma and thus help in better understanding the unrest signals that anticipate eruptions.

The multiple depleted mantle components in the Hawaiian-Emperor chain

Oceanic island basalts are targeted for geochemical study because they provide a direct window into mantle composition and a wealth of information on the dynamics and timescales associated with Earth mixing. Previous studies mainly focused on the shield volcanic stage of oceanic islands and the more fusible, enriched mantle components that are easily distinguished in those basalts. Mantle depleted compositions are typically more difficult to resolve unless large amounts of this material participated in mantle melting (e.g., mid-ocean ridges), or unique processes allow for their compositions to be erupted undiluted, such as very small degrees of melting of a source with minimal fusible enriched components (e.g., rejuvenated basalts) or as xenoliths (e.g., abyssal peridotites). Mantle depleted components, defined here as material with low time-integrated Rb/Sr (low 87Sr/86Sr) and high time-integrated Sm/Nd and Lu/Hf ratios (high 143Nd/144Nd and 176Hf/177Hf) relative to primitive mantle, derive from a potentially very large volume reservoir (up to 80% of the mantle), and therefore need adequate characterization in order estimate the composition of the Earth and mantle-derived melts. This review focuses on mantle depleted compositions in oceanic island basalts using the Hawaiian-Emperor chain as a case study. The Hawaiian-Emperor chain is the ∼6000km long geological record of the deeply sourced Hawaiian mantle plume, active for >81 Myr. Hawaiian volcanism evolves through four volcanic stages as a volcano traverses the Hawaiian plume: alkalic preshield, tholeiitic shield (80–90% volcano volume), alkalic postshield (∼1%), and silica undersaturated rejuvenated (<0.1%). We report Pb-Sr-Nd-Hf isotope compositions and trace element concentrations of three rejuvenated Northwest Hawaiian Ridge basalts and compare them to an exhaustive compiled dataset of basalts from the Hawaiian Islands to the Emperor Seamounts. The Northwest Hawaiian Ridge (NWHR) includes 51 volcanoes spanning ∼42m.y. between the bend in the Hawaiian-Emperor chain and the Hawaiian Islands where there is no high-precision isotopic data published on the rejuvenated-stage over ∼47% of the chain. NWHR and Hawaiian Island rejuvenated basalts are geochemically similar, indicating a consistent source for rejuvenated volcanism over ∼12.5 million years. In contrast, shield-stage basalts from the oldest Emperor Seamounts are more depleted in isotopic composition (i.e., higher 176Hf/177Hf, and 143Nd/144Nd with lower 87Sr/86Sr and 208Pb*/206Pb*) and trace element concentrations (i.e., much lower concentrations of highly incompatible elements) than all other depleted Hawaiian basalts younger than the bend, including NWHR rejuvenated basalts. The strongly depleted source for the oldest Emperor Seamounts (>70 Ma) was likely related to interaction with the Kula-Pacific-Izanagi mid-ocean ridge spreading system active near the Hawaiian plume in the Late Cretaceous. In contrast, the incompatible trace element ratios of NWHR rejuvenated basalts require a distinct source in the Hawaiian mantle plume that was imprinted by ancient (>1 Ga) partial melting, likely ancient recycled oceanic lithosphere. This review of the geochemistry of Hawaiian depleted components documents the need for the sampling of multiple distinctive depleted compositions, each preferentially melted during specific periods of Hawaiian plume activity. This suggests that the composition of depleted components can evolve during the lifetime of the mantle plume, as observed for enriched components in the Hawaiian mantle plume. Changes in the composition of depleted components are dominantly controlled by the upper mantle tectonic configurations at the time of eruption (i.e., proximity to a mid-ocean ridge), as this effect overwhelms the signal imparted by potentially sampling different lower mantle components through time.

The lead-up to the Sturtian Snowball Earth: Neoproterozoic chemostratigraphy time-calibrated by the Tambien Group of Ethiopia

AbstractThe Tonian-Cryogenian Tambien Group of northern Ethiopia is a mixed carbonate-siliciclastic sequence that culminates in glacial deposits associated with the first of the Cryogenian glaciations—the Sturtian “Snowball Earth.” Tambien Group deposition occurred atop arc volcanics and volcaniclastics of the Tsaliet Group. New U-Pb isotope dilution–thermal ionization mass spectrometry (ID-TIMS) dates demonstrate that the transition between the Tsaliet and Tambien Groups occurred at ca. 820 Ma in western exposures and ca. 795 Ma in eastern exposures, which is consistent with west to east arc migration and deposition in an evolving back-arc basin. The presence of intercalated tuffs suitable for high-precision geochronology within the Tambien Group enable temporal constraints on stratigraphic data sets of the interval preceding, and leading into, the Sturtian glaciation. Recently discovered exposures of Sturtian glacial deposits and underlying Tambien Group strata in the Samre Fold-Thrust Belt present the opportunity to further utilize this unique association of tuffs and carbonate lithofacies. U-Pb ID-TIMS ages from zircons indicate that Tambien Group carbonates were deposited from ca. 820 Ma until 0–2 m.y. before the onset of the Sturtian glaciation, making the group host to a relatively complete carbonate stratigraphy leading into this glaciation. New δ13C and 87Sr/86Sr data and U-Pb ID-TIMS ages from the Tambien Group are used in conjunction with previously published isotopic and geochronologic data to construct newly time-calibrated composite Tonian carbon and strontium isotope curves. Tambien Group δ13C data and U-Pb ID-TIMS ages reveal that a pre-Sturtian sharp negative δ13C excursion (referred to as the Islay anomaly in the literature) precedes the Sturtian glaciation by ∼18 m.y., is synchronous in at least two separate basins, and is followed by a prolonged interval of positive δ13C values. The composite Tonian 87Sr/86Sr curve shows that, following an extended interval of low and relatively invariant values, inferred seawater 87Sr/86Sr rose ca. 880–770 Ma, then subsequently decreased leading up to the ca. 717 Ma initiation of the Sturtian glaciation. These data, when combined with a simple global weathering model and analyses of the timing and paleolatitude of large igneous province eruptions and arc accretion events, suggest that the 87Sr/86Sr increase was influenced by increased subaerial weathering of radiogenic lithologies as Rodinia rifted apart at low latitudes. The following 87Sr/86Sr decrease is consistent with enhanced subaerial weathering of arc lithologies accreting in the tropics over tens of millions of years, lowering pCO2 and contributing to the initiation of the Sturtian glaciation.

PRECOCIOUS SECONDARY DENTITION: A CASE REPORT

Chronology of human dentition possesses high variations and deviation from normal eruption timing. However, a significant deviation from routine observations might indicate a need to evaluate patient’s general health and development. This is because tooth eruption is influenced by multiple factors such as genetics, gender, socioeconomic status, craniofacial morphology, systemic diseases, and various syndromes. Presented here is an extremely rare case of early eruption of permanent canines and premolars in an 8-year-old male child. Although the number of such cases is very limited, the clinician should process adequate knowledge and should be vigilant to identify such cases.

Monitoring the internet public opinion of mountain flood disaster using big data analysis

The mountain torrent disasters have caused severe damage and loss of life and property to the society and the economy, which attract the public’s attention. Timely monitoring the characteristics and evolution of internet public opinion in mountain torrents is of significant impact on the emergency response and management. The primary objective of the paper is to analyze the time and spatial characteristics, attention key points, emotional trend and participants of the public opinion in mountain torrent disasters using big data and statistical analysis. The current situation is investigated and a prediction method using correlation analysis is proposed, which provides reference for decision makers to formulate response plans according to public opinion from internet. The data mining method is used to obtain relevant data based on microblog API interface, and the data is processed by statistical methods. Combined with the content analysis method, the characteristics of public opinion in mountain torrents are comprehensively analyzed, and the hotspots of public concern and the trends of public opinion are obtained. The results show that the eruption time of the public opinion coincides with the disaster occurrence time. From spatial characteristics analysis, the flood disasters in China mainly occur in the North China Plain, the middle and lower reaches of the Yangtze River, the Pearl River Basin, the Sichuan Basin, and the Northeast Plain. The public opinion attention degrees are highly positive correlated with the occurrence of mountain torrent disasters, and the correlation coefficient is 0.96. Citizens not only pay attention to the disaster situation and rescue work, but also focus on the improvement of the disaster prevention work. Public emotional trend is mainly based on expressing hope for a safe life, pity and sympathy for the victims, panic about the severity of the disaster, objective evaluation of the situation, as well as admiration and concern for rescuers, and suggestions on early warning education. As an opinion leader, People Daily has great influence on the internet public opinion. At different stages, participants should work together to maintain a healthy public opinion environment.

Ca isotopes record rapid crystal growth in volcanic and subvolcanic systems

Kinetic calcium isotope effects can be used as growth-rate proxies for volcanic and subvolcanic minerals. Here, we analyze Ca isotopic compositions in experimental and natural samples and confirm that large kinetic effects (>2‰) can occur during magmatic plagioclase crystallization. Experiments confirm theoretical predictions that disequilibrium isotope effects depend mainly on the rates for crystal growth relative to liquid phase Ca diffusivity (R/D). Plagioclase phenocrysts from the 1915 Mount Lassen rhyodacite eruption, the ∼650-y-old Deadman Creek Dome eruption, and several mafic subvolcanic orbicules and plagioclase comb layers from Northern California have disequilibrium Ca isotopic compositions that suggest rapid crystal growth rates (>1 cm/y to 15 cm/y). The Ca isotope results, combined with complementary crystal-size distribution analyses, suggest that magmatic rejuvenation (and eruption) events, as reflected in crystal growth times, can be as short as ∼10-3 y. Although mafic systems are predicted to have shorter magmatic rejuvenation periods, we find similarly short timescales in both mafic and silicic systems. These results are consistent with a growing body of evidence suggesting that dominantly crystalline volcanic magma reservoirs can be rapidly reactivated by the injection of fresh magma prior to eruption. By focusing on a common mineral such as plagioclase, this approach can be applied across all major magmatic compositions, suggesting that Ca isotopes can be used as a tool for investigating the dynamics and timing of volcanic eruptions.

Pollen analysis of volcanic ash in Pompeian human skeletal remains

The time of the Vesuvius eruption, which perished Pompeii, Herculaneum and surrounding areas in ad 79, was initially set on the 24–25 August, based on written contemporary documents of the ancient historian Pliny the Younger. This date has been challenged by archaeologists and volcanologists/meteorologists, who moved the time of the eruption further into the autumn and eventually agreed to the final date 23–25 October. The October date has been confirmed by the latest discovery of inscriptions in freshly excavated areas of Pompeii suggesting the mid-late October eruption. In our original project of 2008 we attempted to solve the problem of the eruption time by analysing pollen mixed with falling down volcanic ash, and preserved intact in nasal cavities of the victims in Pompeii. The entire pollen spectrum, 31 different types, was evaluated with the focus on the exact time of the volcanic eruption. No date of eruption could be suggested from this study. The analysis revealed an unusually high amount of pollen from Hedera, an insect pollinated plant flowering from September to October in the area of Pompeii. Among three samples of ash from nasal cavities of two children and an adult considered uncontaminated Hedera pollen was found in noses of both children but not of the adult. This result is the first physical proof of Hedera as medicinal plant used for the treatment of respiratory tract disorders nearly 2000 years ago.

The apex of amphicyonid hypercarnivory: solving the riddle of Agnotherium antiquum Kaup, 1833 (Mammalia, Carnivora)

ABSTRACTSince its first description, only a single undisputed specimen, an isolated, highly abraded m1, was known from the enigmatic amphicyonid Agnotherium antiquum Kaup, 1833. Here, we describe the second specimen of A. antiquum from the type locality of Eppelsheim (early late Miocene, MN 9/10 of Germany), unearthed 184 years after the first description of A. antiquum. The specimen consists of a partial left juvenile mandible with dp3, m1 in eruption, i3, canine, p4, and a highly reduced m2 still in crypt. The p1–3 and m3 are completely reduced, as are the metaconids of m1 and m2. We confirm previous assignments of late Miocene specimens from the localities of Charmoille, Switzerland, and Pedregueras 2A, Spain, to A. antiquum, whereas a maxilla from Bled Douarah, Tunisia, can only tentatively be assigned to the species. We confirm that the monotypic genus Agnotherium is a thaumastocyonine amphicyonid, discuss other supposed thaumastocyonine specimens, and briefly review the evolutionary history of the subfamily. Agnotherium was a 275 kg, extremely powerful, strictly carnivorous ambush hunter that represents the apex of amphicyonid evolution toward carnivory. Its tooth eruption pattern resembles recent Ursus more than recent Canis, but it shows a considerable delay of eruption timing like in the ursid Agriotherium. Agnotherium antiquum is one of six carnivoran species from the Eppelsheim Formation that is heavier than 200 kg. The co-occurrence of Agnotherium (or its relatives Tomocyon and Thaumastocyon), Machairodus, and a smaller saber-toothed carnivoran is typical for early late Miocene faunas of Europe and tentatively North Africa.

Development of primary teeth among infants and toddlers in nine cities of China in 2015

Objective: To investigate the status of the development of primary teeth and to identify the development patterns among infants and toddlers in nine cities of China in 2015. Methods: Healthy children aged 1-<36 months were investigated by across-sectional survey and retrospective studies, which was carried out in 9 cities (Beijing, Harbin and Xi'an in northern China; Shanghai, Nanjing and Wuhan in central China; and Guangzhou, Fuzhou and Kunming in southern China) from June to October in 2015. Subjects (n=103 995) were divided into 14 age groups (1-<2, 2-<3, 3-<4, 4-<5, 5-<6, 6-<8, 8-<10, 10-<12, 12-<15, 15-<18, 18-<21, 21-<24, 24-<30, 30-<36 months). There were 150-200 boys and girls respectively in each group of urban and suburb areas in each city. The eruption status and the number of primary teeth were examined by the trained child health care physician or pediatrician on the spot. The timing of primary teeth eruption of children was retrospectively surveyed using a questionnaire. The prevalence of primary teeth was calculated and χ(2) test was used for comparison of categorical data. Probit regression analysis was used to determine the median and percentile age of eruption of primary teeth. Results: Totally 103 995 children aged 1-<36 months were investigated. There were 52 346 children in urban areas (boys 26 228, girls 26 118) and 51 649 children in suburb areas (boys 25 912, girls 25 737). The eruption rate of primary teeth in children under 2 years became higher with age and the difference among each age group was statistically significant (χ(2)=85 913.868, P<0.01), which was 0.3% (22/7 450) in 3-<4 months group, 43.0% (3 227/7 503) in 6-<8 months group and 99.9% (7 441/7 446) in 15-<18 months group. The eruption age of primary teeth was 6.6 months (95%CI: 6.5-6.7 months), and the range of the 3rd to 97th percentile was 4.1-10.6 months. The eruption ages of primary teeth in urban and suburb areas children were 6.6 months (95%CI: 6.5-6.7 months) and 6.6 months (95%CI: 6.5-6.7 months) respectively. The eruption age of primary teeth was earlier in boys (6.4 months, 95%CI: 6.3-6.5 months) than that in girls (6.7 months, 95%CI: 6.6-6.8 months). The median eruption age of primary teeth was earlier in northern China (6.2 months) than that in central (6.7 months) and southern China (6.9 months). The eruption rate of primary teeth became higher with age, showing that the median number of primary teeth was 2 in 8-<10 months group, 8 in 12-<15 months group and 20 in 30-<36 months group. Conclusions: The timing of eruption of primary teeth was similar between urban and suburb areas children and that of the boys was slightly earlier than that of the girls. There were slight differences among different regions in the eruption timing of primary teeth. The range of the 3rd to 97th percentile in the eruption age of primary teeth was 4.1-10.6 months and the number of primary teeth followed the regular development pattern with age.

The incidence and extraction causes of third molars among young adults in Poland

Despite many years of observation, the issue of third molars is still open for discussion. Among human teeth, third molars vary the most in number and morphology, which results from genetic changes and environmental factors affecting the evolution of the human dentition. This research aims to study various aspects of third molars in the population of young Poles, such as the incidence, time of eruption and causes of extraction in men and women. The analyses consider the socio-economic status of the respondents, including the frequency of visits to the dentist. Eight hundred students, aged 19–25 (14.4% of men and 85.6% of women) of the universities located in Wroclaw, Poland, took part in an online questionnaire survey. The incidence of third molars was smaller in the women (32.4–34.9%) than in men (47.8–56.5%) (p&lt;0.001). For both sexes, the most frequent causes of extraction were abnormal tooth position (29.6–54.5%) and orthodontic treatment (15.5–27.3%). Both incidence and causes of extraction were related for all the examined pairs of teeth (upper–lower teeth and right–left teeth). The men (17.94–18.49 year) and women (18.42–18.83 year) did not differ in the mean age of their third molars’ eruption. The men visited the dentist less often than the women did (p&lt;0.001). The study presents original research and confronts it with published results. Despite the limitations of an online survey, the results can contribute to more advanced research conducted on a larger scale. In particular, more detailed research is recommended for the Polish population, for which such studies are scarce.

Factores influyentes en el periodo de erupción del primer diente primario.

Introduction: Deciduous teeth play an important role in proper growth. Tooth eruption is a complicated process in which different mechanisms are involved. Early or delayed tooth eruption depends on different factors, with the impact of some already established. There are apparent controversy regarding the effect of some factors on time of the first deciduous tooth eruption among the conducted studies. The current study aimed to evaluate factors affecting the time of the first deciduous tooth eruption. Materials and Methods: One hundred and sixty eligible infants referring to the healthcare centers of Tabriz, Iran, were randomly selected; the demographic data including weight and height at birth, head circumference, mother’s age and level of education, birth rank in the family and type of feeding were recorded, in addition to the time of the first deciduous tooth eruption. Data were analyzed using SPSS version 21 by ANOVA and t test.Results: Out of 54.1% female and 45.9% male participating infants, 78.3% had normal weight at birth. Results showed a significant relationship between weight at birth and timing of the first deciduous tooth eruption, among the evaluated factors. Conclusions: Although no significant relationship was observed between gender, type of feeding, mother’s level of education and birth rank in the family, and time of the first deciduous tooth eruption, there was a significant relationship between the weight at birth and the timing of the first deciduous tooth eruption. Infants with higher or lower abnormal weight at birth had delayed deciduous tooth eruption.

Combining Magma Flow and Deformation Modeling to Explain Observed Changes in Tilt

The understanding of magma ascent dynamics is essential in forecasting the scale, style and timing of volcanic eruptions. The monitoring of near-field deformation is widely used to gain insight into these dynamics, and has been linked to stress changes in the upper conduit. The ascent of magma through the conduit exerts shear stress on the conduit wall, pulling up the surrounding edifice, whilst overpressure in the upper conduit pushes the surrounding edifice outwards. H\sout{owever, h}ow much shear stress and pressure is produced during magma ascent, and the relative contribution of each to the deformation, \sout{is yet to be fully understood and quantified}\textcolor{blue}{has until now only been explored conceptually}. By combining flow and deformation modelling using COMSOL Multiphysics, we \sout{are} for the first time \sout{able to}\textcolor{blue}{present a quantitative model that links magma ascent to deformation. We} quantify how both shear stress and pressure vary spatially within a conduit, and show that shear stress generally dominates observed changes in tilt close to the conduit during activity at Tungurahua volcano, Ecuador, between 2013 and 2014. However, the relative contribution of pressure is not insignificant, and \sout{the full stress tensor comprising} both pressure and shear stress must be considered when interpreting deformation data. We demonstrate that significant changes in tilt \sout{can occur as magma refills an empty conduit, or} can be driven by changes in the driving pressure gradient or volatile content of the magma. The relative contribution of shear stress and pressure to the tilt varies considerably depending on these parameters. Our work provides insight into the range of elastic moduli that should be considered when modelling edifice-scale rock masses, and we show that even where the edifice is modelled as weak, shear stress \textcolor{blue}{generally} dominates the near field deformation over pressurisation of the conduit.

History of scoria‐cone eruptions on the eastern shoulder of the Kenya–Tanzania Rift revealed in the 250‐ka sediment record of Lake Chala near Mount Kilimanjaro

ABSTRACTReconstructions of the timing and frequency of past eruptions are important to assess the propensity for future volcanic activity, yet in volcanic areas such as the East African Rift only piecemeal eruption histories exist. Understanding the volcanic history of scoria‐cone fields, where eruptions are often infrequent and deposits strongly weathered, is particularly challenging. Here we reconstruct a history of volcanism from scoria cones situated along the eastern shoulders of the Kenya–Tanzania Rift, using a sequence of tephra (volcanic ash) layers preserved in the ~250‐ka sediment record of Lake Chala near Mount Kilimanjaro. Seven visible and two non‐visible (crypto‐) tephra layers in the Lake Chala sequence are attributed to activity from the Mt Kilimanjaro (northern Tanzania) and the Chyulu Hills (southern Kenya) volcanic fields, on the basis of their glass chemistry, textural characteristics and known eruption chronology. The Lake Chala record of eruptions from scoria cones in the Chyulu Hills volcanic field confirms geological and historical evidence of its recent activity, and provides first‐order age estimates for seven previously unknown eruptions. Long and well‐resolved sedimentary records such as that of Lake Chala have significant potential for resolving regional eruption chronologies spanning hundreds of thousands of years.

Recent Eruptions Between 2012 and 2018 Discovered at West Mata Submarine Volcano (NE Lau Basin, SW Pacific) and Characterized by New Ship, AUV, and ROV Data

West Mata is a submarine volcano located in the SW Pacific Ocean between Fiji and Samoa in the NE Lau Basin. West Mata was discovered to be actively erupting at its summit in September 2008 and May 2009. Water-column chemistry and hydrophone data suggest it was probably continuously active until early 2011. Subsequent repeated bathymetric surveys of West Mata have shown that it changed to a style of frequent but intermittent eruptions away from the summit since then. We present new data from ship-based bathymetric surveys, high-resolution bathymetry from an autonomous underwater vehicle, and observations from remotely operated vehicle dives that document four additional eruptions between 2012-2018. Three of those eruptions occurred between September 2012 and March 2016; one near the summit on the upper ENE rift, a second on the NE flank away from any rift zone, and a third at the NE base of the volcano. The latter intruded a sill into a basin with thick sediments, uplifted them, and then extruded lava onto the seafloor around them. The most recent of the four eruptions occurred between March 2016 and November 2017 along the middle ENE rift zone and produced pillow lava flows with a shingled morphology and tephra as well as clastic debris that mantled the SE slope. ROV dive observations show that the shallower recent eruptions at West Mata include a substantial pyroclastic component, based on thick (>1m) tephra deposits near eruptive vents. The deepest eruption sites lack these near-vent tephra deposits, suggesting that pyroclastic activity is minimal below ~2500 mbsl. The multibeam sonar re-surveys constrain the timing, thickness, area, morphology, and volume of the new eruptions. The cumulative erupted volume since 1996 suggests that eruptions at West Mata are volume-predictable with an average eruption rate of 7.8 x 106 m3/yr. This relatively low magma supply rate and the high frequency of eruptions (every 1-2 years) suggests that the magma reservoir at West Mata is relatively small. With its frequent activity, West Mata continues to be an ideal natural laboratory for the study of submarine volcanic eruptions.