Absolute Age Research Articles

Optimizing fungicide application timing for spring dead spot based on soil temperature and season

AbstractSpring dead spot (SDS) (Ophiosphaerella spp.) is the most detrimental disease to warm‐season turfgrasses in areas with cold‐induced dormancy. Fungicide applications do not provide consistent SDS suppression. One reason for this inconsistency is the use of solely calendar‐based fungicide applications instead of considering both calendar date and soil temperature. A field study was conducted at three separate hybrid bermudagrass (Cynodon dactylon (L.) Pers. × transvaalensis Burtt Davy) locations in Virginia to determine the optimal soil temperature and timing for SDS suppression with tebuconazole and isofetamid. Tebuconazole (1.5 kg a.i. ha−1) and isofetamid (4.1 kg a.i. ha−1) were applied at 11 different timings throughout the year based on soil temperatures at a 0‐ to 10‐cm depth. Plots were assessed for SDS severity in the spring and early summer of 2021 and 2022. Two in vitro studies were also conducted with Ophiosphaerella herpotricha and Ophiosphaerella korrae isolates to (1) determine the optimal temperature for growth on potato dextrose agar (PDA) placed on a thermogradient table (13–33°C) and (2) compare the daily growth rate of O. herpotricha and O. korrae isolates at 11, 19, and 27.5°C on PDA. In the field study, isofetamid suppressed SDS more than tebuconazole. Fall applications when soil temperatures were 13°C consistently provided the best SDS suppression. For the in vitro studies, both species grew optimally between 24 and 25°C, yet O. korrae and O. herpotricha growth rates differed at 11°C.

El Zorro: early Jurassic intrusion-related gold (IRG) mineralization in the oldest, western-most segment of the Andean Cordillera of Northern Chile

AbstractThe El Zorro gold district is the most recent gold discovery in the Coastal Cordillera of northern Chile. Ternera is the largest deposit in the district with total resources currently estimated at 1.282 Moz. New geology, geochemistry and geochronology data indicate that hydrothermal mineralization is mostly hosted within felsic to intermediate, ilmenite-bearing calc-alkaline dikes and stocks of the Upper Triassic to Lower Jurassic Relincho Pluton, and some of the adjacent Devonian to Carboniferous metasediments of the Chañaral Epimetamorphic Complex. Sheeted veins, veinlets, and fault zones with quartz, low amounts of pyrite, pyrrhotite and arsenopyrite, and local calcite are surrounded by narrow haloes of albite-biotite-quartz ± sulfides-K-feldspar-sericite-chlorite. Gold (mostly in the veins) is associated with elevated W-Bi and also As-Te-Sn, and not with iron enrichment or base metals, even though this system is proximal (~ 20 km) to IOCG and IOA deposits of the Coastal Cordillera. The main phase of gold mineralization occurred soon after emplacement of tonalitic dikes and granodiorite from the Relincho and Cuevitas plutons (U–Pb zircon between ~ 205 and 190 Ma), about 80 m.y. later than the development of orogenic fabrics. An absolute upper age limit is provided by compositionally distinct ore-cutting mafic dikes dated at 175–170 Ma (U–Pb apatite). The deposit falls into the intrusion-related gold category, as indicated by the cutting of earlier orogenic fabrics, the metal and alteration associations, and the spatial and temporal connection to reduced ilmenite-series intrusions, which are also very similar geochemically to the ‘type-locality’ IRG intrusions of the Tintina Belt in Yukon/Alaska. The El Zorro gold district represents the oldest and geologically western-most mineralizing event in the Central Andes of northern Chile, consistent with its time–space placement within the tectonic framework of easterly-younging mineralization and igneous activity in the Chilean Cordillera.

Radiocarbon dating and isotopic paleoecology of Notiomastodon platensis (Mammalia: Proboscidea) from the late Pleistocene of Minas Gerais, Brazil

Proboscidea is a group of large mammals abundant in the fossil record and in Brazil it is represented by Notiomastodon platensis (Ameghino, 1888). To improve the understanding on its taxonomy, chronology, annual diet, and habitats paleoenvironmental aspects, we conducted a morphological description, absolute dating, and analysis of stable isotopes of carbon and oxygen (δ13C and δ18O) in Notiomastodon' remains from the northern (Norte de Minas) and western (Triângulo Mineiro) mesoregions of Minas Gerais State, Brazil. The material includes isolated teeth, mandibular portions, and postcranial bones at different levels of fragmentation, associated with at least eight adults and one juvenile. The only individual from Triângulo, found in Campina Verde municipality, was dated at 27,715–27,903 Cal yr BP. It presented a mixed diet based on C4 plants (piC4 = 90 %; δ13C = 0.5 ‰), which implies the occupation of an open environment, mostly pasture. The region was relatively humid (δ18O = 24.7 ‰), which is supported by the existence of humidity corridors in the Amazon region. A similar phytophysiognomy was inferred for the Norte de Minas region between at least 21,966–22,279 Cal yr BP and 18,944–19,157 Cal yr BP. However, one specimen showed a different δ13C value (piC3 = 0.87 %; δ13C = −10.2 ‰). This indicates it lived in a transitional environment between low-density forest and arboreal savannah. This likely occurred during a period that favored the expansion of trees and shrubs. The region underwent climate change, from relatively humid conditions (δ18O = 25.6 ± 0.2 ‰) to expressively dry (δ18O = 34.6 ‰) between the dated periods, a change corroborated by some palynological data. The multiannual paleoecological analysis, based on sequential sampling of three dentin layers of an incisor, indicated the relative stability of vegetation and climate despite fluctuations in hydrology. The perceived disassociation between vegetation dynamics and local hydrology corroborates the idea that factors other than precipitation may play a significant role in the environmental dynamics of the Cerrado biome.

Extremely rapid, yet noncatastrophic, preservation of the flattened-feathered and 3D dinosaurs of the Early Cretaceous of China

Northeast China's Early Cretaceous Yixian Formation preserves spectacular fossils that have proved extraordinarily important in testing evolutionary hypotheses involving the origin of birds and the distribution of feathers among nonavian dinosaurs. These fossils occur either flattened with soft tissue preservation (including feathers and color) in laminated lacustrine strata or as three-dimensional (3D) skeletons in "life-like" postures in more massive deposits. The relationships of these deposits to each other, their absolute ages, and the origin of the extraordinary fossil preservation have been vigorously debated for nearly a half century, with the prevailing view being that preservation was linked to violent volcanic eruptions or lahars, similar to processes that preserved human remains at Pompeii. We present high-precision zircon U-Pb geochronology from cores and outcrops, demonstrating that Yixian Formation accumulation rates are more than an order of magnitude higher than usually estimated. Additionally, we provide zircon provenance and sedimentological data from 3D dinosaur fossils, which imply that their death and burial occurred in collapsed burrows, rather than via a catastrophic volcanogenic mechanism. In the studied area, the three principal fossil-rich intervals of the Yixian occur as a cyclic sequence that correspond to periods of high precipitation. Using Bayesian-Markov Chain Monte Carlo approaches, we constrain the total duration of the sequence to less than ~93,000 y and suggest that climatic precession paced the expression of these cyclic sediments. Rather than representing multiple, Pompeii-like catastrophes, the Yixian Formation is instead a brief snapshot of normal life and death in an Early Cretaceous continental community.

Protracted (>100 m.y.) deep crustal orogenesis revealed by in situ monazite petrochronology in the Shuswap Metamorphic Complex, British Columbia, Canada

The Shuswap Metamorphic Complex in southeastern British Columbia, Canada, exposes penetratively deformed rocks exhumed from deep crustal levels (∼25−30 km depth) of the Canadian Cordillera. Existing models describing its tectonometamorphic evolution are not directly linked to absolute age constraints acquired through modern petrochronological methods and, therefore, remain ambiguous. To differentiate between proposed models, here we apply U-Th-Pb monazite petrochronology, petrological modeling, and microstructural analysis to quantify conditions and timing of deformation across a transect of the Shuswap Metamorphic Complex. Our results demonstrate that metamorphism decreases in age with increased structural depth associated with progressive localization of NE-directed shearing toward the base of the Shuswap Metamorphic Complex. Monazite U-Th-Pb age data from the structural level exposed in the study area are consistent with protracted northeast-directed compression from ca. 167 Ma to ca. 59 Ma, after which west-directed ductile extension continued until at least ca. 49 Ma and was progressively localized along the Okanagan Valley fault system. New data presented are consistent with a model of basal accretion in front of a foreland-propagating ductile thrust system, followed by exhumation of the Shuswap Metamorphic Complex facilitated in large part by crustal-scale extension.

An Absolute Mass, Precise Age, and Hints of Planetary Winds for WASP-121A and b from a JWST NIRSpec Phase Curve

We have conducted a planetary radial velocity measurement of the ultrahot Jupiter WASP-121b using JWST NIRSpec phase curve data. Our analysis reveals the Doppler shift of the planetary spectral lines across the full orbit, which shifts considerably across the detector (∼10 pixels). Using cross-correlation techniques, we have determined an overall planetary velocity amplitude of K p = 215.7 ± 1.1 km s−1, which is in good agreement with the expected value. We have also calculated the dynamical mass for both components of the system by treating it as an eclipsing double-line spectroscopic binary, with WASP-121A having a mass of M ⋆ = 1.330 ± 0.019 M ⊙, while WASP-121b has a mass of M p = 1.170 ± 0.043 M Jup. These dynamical measurements are ∼3× more precise than previous estimates and do not rely on any stellar modeling assumptions that have a ∼5% systematic floor mass uncertainty. Additionally, we used stellar evolution modeling constrained with a stellar density and parallax measurement to determine a precise age for the system, found to be 1.11 ± 0.14 Gyr. Finally, we observed potential velocity differences between the two NIRSpec detectors, with NRS1 lower by 5.5 ± 2.2 km s−1. We suggest that differences can arise from day/night asymmetries in the thermal emission, which can lead to a sensitivity bias favoring the illuminated side of the planet, with planetary rotation and winds both acting to lower a measured K P. The planet’s rotation can account for 1 km s−1 of the observed velocity difference, with 4.5 ± 2.2 km s−1 potentially attributable to vertical differences in wind speeds.

The queuing system of a scientific journal

The results of the research difference of the calendar date between begining and ending editorial processes in the Journal of “Almaz – Antey” Air and Space Defence Corporation are given, and the counting of dates per month for beginning the processes (entering articles, transferring to literacy editing etc.). Based on the analysis it was concluded that the incoming article might be considered as an incoming application to queuing system, which the scientific journal is. For such incoming application can be estimate the distribution functions incoming flows, average and maximum term be in queuing system, also as the distribution functions of the service mode and another characteristics, which stay unchanged (stationary) in time for researched scientific journal.

Prognostic assessment based on the trajectory of artificial intelligence-enabled electrocardiograms for age estimation

Abstract Background Artificial Intelligence (AI) estimation of age using data from the 12-lead electrocardiogram (ECG) has demonstrated its utility as a biomarker in predicting the future risk of cardiac diseases and mortality. However, expected long-term outcomes based on temporal changes in the AI-ECG age gap remain unclear. Purpose This study aims to utilize the difference between ages predicted by AI-ECG and actual ages longitudinally for follow-up and to assess whether there are significant clinical differences in mortality among specific groups. Methods Among patients at a hospital who had not been used for the AI-ECG age prediction model (121,702 individuals, 522,261 ECGs), 6,685 individuals with 31,858 ECGs who had an index ECG and the subsequent ECG in the fifth year, with at least one intervening ECG were included for analysis. The absolute age gap, defined as the absolute difference between ECG-predicted and chronological age, was limited to ±10 for analysis. Latent class trajectory modeling was then utilized to classify groups based on the AI-ECG age gap. Results Data-driven analysis revealed four distinct trajectory groups based on age gap trajectories: Consistently Young ECG (27.2%), Reversed ECG Aging (35.3%), Accelerated ECG Aging (8.0%), and Consistently Old ECG (29.5%). Notably, the Accelerated ECG Aging group exhibited a significantly higher cumulative incidence of all-cause death (adjusted hazard ratio (HR) 1.66 (95% confidence interval (CI) 1.30-2.12, p-value <0.001) and non-cardiac death (adjusted HR 1.83 (95% CI 1.38-2.43, p-value <0.001) compared to the Consistently Young ECG group. Conclusion Among 4 distinct trajectories based on the changes in the AI-ECG age gap, Accelerated ECG Aging was associated with a heightened risk of all-cause mortality. Additional in-depth analysis of factors associated with Accelerated ECG Aging is warranted.

Artificial intelligence for predicting arctic permafrost and active layer temperatures along the Alaskan North Slope

AbstractClimate change in Arctic regions poses a threat to permafrost stability, potentially leading to issues such as infrastructure damage, altered ecosystems, and increased greenhouse gas emissions. The challenge of monitoring permafrost temperatures and identifying critical environmental factors is accentuated by the scarcity of subsurface thermal data in remote Arctic locales. To alleviate this lack of soil thermal data we set out to combine in situ observed soil temperatures with MERRA-2 reanalysis data and Machine Learning (ML) to develop local and season-specific subsurface soil temperature predictions in Alaska. First, reanalysis features are selected based on surface energy budget physics. Coupled with Julian calendar dates, reanalysis features are preprocessed and then fed to the ML prediction model. We conducted a series of computational experiments and tested the results against performance benchmarks to determine the optimal prediction models, length of look-back period of model inputs, and the training set size. Six conventional ML models (e.g., GBDT, RF, SVR) and five statistical baselines (e.g. ARIMA) using in situ time series of soil temperature data ranging from 0 - 1 m depth are considered for the prediction task. The models are trained using in situ soil temperatures at depths between 0 and 1 m, spanning 16+ years, from field sites at Deadhorse and Toolik Lake, Alaska. All prediction performances are assessed using root mean squared error (RMSE) and mean absolute error (MAE). Results show that locally trained ML models can estimate shallow soil temperatures with an average error of $$RMSE=1.308^{\circ }$$ R M S E = 1 . 308 ∘ C.

Aeolian sand cover on a granite peninsula (Hammeren, Bornholm, Baltic Sea) formed in three episodes during the past 11,600 years

Aeolian sand covers a significant part of the granite peninsula Hammeren on northernmost Bornholm in the Baltic Sea. The coastline of Hammeren is rocky and apart from one relative wide and sandy pocket beach at the east coast only few, small and gravelly pocket beaches exist. The aeolian deposits form three sand covers that stretch inland from the east and northwestern facing coasts of Hammeren. The largest sand cover forms a rising sand plain that cover the granitic landscape up to 700 m inland and reaches up to 60 m above sea level. Historical sources mention aeolian sand movement around CE 1775 in the middle of the Little Ice Age, but until this study no absolute age control has been available to confirm these observations. Luminescence dating of selected sample sites indicates that aeolian sand movement took place in three episodes. The first episode was in the last part of the Younger Dryas at about 11,500 BP, the second episode was in the Danish Late Bronze Age at about 2700 BP, and the youngest episode was indeed during the Little Ice Age around 200 BP (CE 1750). These episodes with aeolian activity all fall during relatively cold climatic intervals and add support to previous studies indicating a link between cold climates an increased storminess in Northwest Europe including the southern Baltic Sea region.

Analysis of fauna of mollusks, pollen assemblages and sedimentary environments in the Taganrog Bay of the Sea of Azov

The paper presents the results of a comprehensive study of well sections drilled on the coastal spits of the Taganrog Gulf of the Sea of Azov and bottom sediment columns selected in the water area. A detailed analysis of the early malacological communities, an important participant in the sedimentary process, made it possible to trace changes in their living conditions in the Holocene. Based on determining the absolute age (14C) from the valves of mollusk shells buried in situ, it is shown that at the beginning of the Phanagorian regression, in the area of the distal part of the Dolgaya Spit, there was a sea reservoir with an Azov-Black Sea complex of reference species. Based on the results of palynological analysis, changes in the natural conditions of the Azov region over the past few thousand years have been reconstructed and arid and humid climatic phases have been identified.

Geology and geochronology of the El Peñón granitic pluton: A contribution to the famatinian magmatic evolution in the Sierra de San Luis, Argentina

The El Peñón pluton is a peraluminous granite located in the northeastern sector of the Sierra de San Luis. According to its textural and mineral variations two endmember facies have been distinguished along it: a coarse-grained muscovite-bearing facies, and a fine-grained biotite-bearing facies. Field relationships aligned with mineralogical and geochemical compositions, allow us to establish an anatectic origin for this pluton. Regarding the inherited zircon ages, the provenance area of the metasedimentary source could be linked to the orogenic systems of Western Gondwana. The analysis of the internal structure of the intrusive body related with the structural arrangement observed in the country rocks indicates a syn-kinematic emplacement of the igneous body with respect to the main deformational event described in the Sierra de San Luis, which has been assigned to the closure of the Famatinian arc. New U-Pb (LA-ICP-MS) zircon ages constrain the emplacement/crystallization age of the El Peñón granite within the time lapse between ∼470 and 460 Ma. The geochronological data presented here, together with geochemical and structural analysis, enables us to correlate the origin of the El Peñón pluton and the deformation that occurred during its emplacement with the Famatinian Orogeny. Thus, these results allow us to rule out the presence of Pampean magmatism in the Sierra de San Luis but also establish a new absolute age for the main deformational event of the range.

New zircon U-Pb age of the top Duoni Formation, Basu County: constraits on the collision between Qiangtang and Lhasa blocks in Eastern Tibet

The Duoni Formation is widely distributed along the Bangong-Nujiang suture belt and surrounding blocks in Tibet, serving as a key sedimentary record of the collision between the Qiangtang and Lhasa blocks. The upper sections of the formation typically contain andesite, volcanic rocks and tuff offering potential for precise stratigraphic correlations across the suture belt. The Duoni Formation in the central and western belt has been well-constrained geochronologically through zircon U-Pb dating; however, the insufficient age constraints on Duoni Formation in eastern Tibet hinder effective stratigraphic correlation and limit the understanding of the timing of this collision. Building on prior stratigraphic and paleontological studies, we collected three tuff samples from the upper Duoni Formation at the Wada coal mine section in Basu County, eastern Tibet. Zircon U-Pb dating was used to determine the age of the Duoni Formation, yielding results of 112.8 ± 1.0 Ma for sample XZ01, 111.48 ± 0.37 Ma for sample XZ03, and 110.95 ± 0.41 Ma for sample XZ05. These absolute ages correspond with early Albian and are generally consistent with those absolute ages from the central and western suture belt. Our study therefore suggests the similar timing for the Qiangtang-Lhasa collision across the whole Bangong-Nujiang belt.

The Absolute Age First Determination of the 3rd Terrace Deposits from Transilvania, Using Optically Stimulated Luminescence Method

For determining the absolute age of the terrace deposits, a geomorphosite located on the left side of Someşul Mare river, southeast of Rebrişoara was selected, which includes a fragment of the tread of the 3<sup>rd</sup> terrace (20-21 m relative altitude) and the cuesta slope, facing north the Făgetului Hills. The question regarding the age of fluvial terraces has been long debated in Romanian geomorphological literature age since the beginning of the 20<sup>th</sup> century. Many geomorphologists have carried out studies wherein the question of the age of the terraces, both inside the Carpathian curvature and outside, was raised. Most of the studies carried out for the terraces on the rivers of the Transylvanian Basin indicated the age of the 3<sup>rd</sup> terrace as Wurmian. Until recently, most assumptions related to the age of the terraces were based on the correlation between terraces and/or by dating the paleontological fossils discovered in the terrace deposits. Recent studies, on the other hand, use high-precision methods to determine the ages of terrace formations. Researchers, use methods like the Infrared-stimulated luminescence dating (IRSL) and SAR-OSL (Optically Stimulated Luminescence). Within this context, the present study focuses on the attempt to determine the age of the 3<sup>rd</sup> terrace in the corridor of the Someșul Mare river. In the alluvial formations of this terrace, two geologic drillings were carried out from where several samples were collected. They were subjected to OSL analysis at the Luminescence Dating Laboratory, Department of Geoinformatics, Physical and Environmental Geography, University of Szeged, Hungary. The results showed an older age of the 3<sup>rd</sup> terrace than it has been believed until now.

Zircon U–Pb CA–ID–TIMS constraints on the chronology of the Late Carboniferous–early Permian continental Döhlen Basin and its correlation with the Thuringian Forest Basin (Central and Eastern Germany)

We present new zircon U–Pb chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA–ID–TIMS) ages of two Late Carboniferous–early Permian continental basins in Germany. Three volcanic rocks from the Döhlen Basin (Saxony), and two tuff samples of the Thuringian Forest Basin (Thuringia) were dated. Our data indicate that all four formations of the Döhlen Basin were deposited in the interval of approx. 300 Ma to 298 Ma. The tuff samples of the Thuringian Forest Basin provided ages that overlap with the Döhlen Basin data. The Niederhäslich Formation of the Döhlen Basin and the Manebach and Goldlauter formations of the Thuringian Forest Basin contain fossil-rich lacustrine horizons, which have been correlated to a variety of formations in other European basins through the use of insect, amphibian, or conchostracan assemblage zones. Our new data thus provide new absolute age constraints for different fossil assemblage zones. Furthermore, the data can be considered a strong indication for simultaneous large-scale volcanic activity between 300 and 298 Ma. A relation between volcanic and post-Variscan transtensional tectonic activity is proposed because both the Döhlen Basin and the Thuringian Forest Basin are bound to NW trending strike-slip faults.Graphical abstract

The initial spread of peaches across eastern North America was structured by Indigenous communities and ecologies

We conduct a synthetic archaeological and ethnohistoric dating program to assess the timing and tempo of the spread of peaches, the first Eurasian domesticate to be adopted across Indigenous eastern North America, into the interior American Southeast by Indigenous communities who quickly “Indigenized” the fruit. In doing so, we present what may be the earliest absolute dates for archaeological contexts containing preserved peach pits in what is today the United States in the early to mid-16th century. Along with our broader chronological modeling, these early dates suggest that peaches were likely in the interior prior to permanent Spanish settlement in the American Southeast and that peaches spread independently of interactions with Spanish colonizers. We further argue that that eventual spread of peaches was structured exclusively by Indigenous communities and the ecologies produced through long-term Indigenous land management and land use practices, highlighting and centering the agency of Indigenous societies in the socioecological process of colonization.

The Neogene of the Vienna Basin – a synthesis

We present a revision of geological and paleontological data of the Vienna Basin (VB). The deposits comprise Miocene terrestrial, lacustrine and marine sediments, corresponding the Ottnangian, Karpatian, Badenian, Sarmatian and Pannonian regional stages (= Burdigalian to Tortonian). New 3D seismics and the analyses of hundreds of core samples resulted in a wealth of information. Absolute ages were published for two tuffs and the lithostratigraphy was largely formalized. The evolution of the paleoenvironments in the VB strongly reflects the impact by global climatic events such as the Miocene Climatic Optimum, the Middle Miocene Climate Transition and the Tortonian Thermal Maximum. Global 3 rd order sea level cycles are reflected in the successions of marine depositional environments. Major drops of the relative sea level caused strong erosion along the basin margins, with up to 300 m paleorelief. The strongest phase of erosion was linked to tectonics. Around the Early/Middle Miocene boundary, Lower Miocene strata became tilted during the Styrian Tectonic Phase. Up to 600-m-deep subaerial canyons incised the VB at that time. A second phase of basin-wide erosion occurred during the Late Miocene when more than 200 m of upper Pannonian strata became removed from large parts of the VB after 9 Ma.

Cardiometabolic Risk in a University Community: An Observational Study.

The highest prevalence of cardiovascular risk factors has been associated with obesity, sedentary lifestyle, and elevated blood pressure due to high workload and work stress. This study aimed to analyze the cardiometabolic risk and lifestyles among the health sciences university academics and campus administrators at a private university in Spain. A cross-sectional study was conducted during the 2018-2019 academic year by the Nursing Department, using a self-administered questionnaire and face-to-face assessments of anthropometric variables related to cardiovascular risk in university personnel. The variables measured included sociodemographics, cardiovascular risk history, comorbidities, toxic habits, Mediterranean diet adherence, physical exercise, psychosocial stress, and physical, anthropometric, and analytical data. Cardiovascular risk was categorized into relative (<40 years), absolute, and vascular age (>40 years). Among the 101 participants, 61.4% were women, with a mean age of 41.3 years ± 9 years. The smoking prevalence was 21.8% (68.2% women), 27.7% were sedentary, and 51.0% adhered to the Mediterranean diet, with higher adherence among the academics. Emotional risk was present in 32.7% of the participants. A prior diagnosis of hypertension was significantly more frequent in the men (15.4%) compared to the women (3.2%). The blood pressure measurements were mostly optimal across both genders and professional groups, but the proportion of hypertension grade 1 was significantly higher among the academics (10%) compared to the administrators (4.5%) and among the men (11.1%) compared to the women (5.9%). The absolute cardiovascular risk among the university employees was generally low, but the men exhibited a more moderate risk compared to the women. It is necessary for the university to promote health within its community, with the Nursing Department playing a key role in health promotion and research.

Update on the 53Mn-53Cr ages of dolomite in the Ivuna CI chondrite and asteroid Ryugu sample

Aqueous alteration in planetesimals is one of the earliest geological processes in the solar system. The timing of aqueous alteration sheds light on the timescale of material evolution through water–rock interaction in small bodies. The 53Mn-53Cr decay system, where a short-lived radionuclide 53Mn decays to 53Cr with a half-life of 3.7 Myr, is a powerful tool for dating carbonates in primitive meteorites that formed during aqueous alteration. In CI chondrites and samples returned from asteroid Ryugu, a major carbonate mineral is dolomite (CaMg(CO3)2) and could be dated precisely because of their relatively high Mn abundances. However, the lack of a proper dolomite standard for secondary ion mass spectrometry (SIMS) hinders us from obtaining accurate Mn/Cr ratios of carbonates, resulting in erroneous formation ages. In this work, we synthesized Mn-, Cr-, and Fe-bearing crystalline dolomite as standard materials and evaluated the relative sensitivity factor (RSF) of Mn/Cr for SIMS analysis, namely, the ratio of Mn/Cr obtained using SIMS to true Mn/Cr. We found that the RSF values of the dolomite standards range from 0.8 to 0.9, slightly higher than that of calcite (CaCO3) (∼0.7), and increase with their Fe contents. We used the newly evaluated RSF values to date dolomite in the Ivuna CI chondrite and obtained an initial 53Mn/55Mn ratio of (3.95 ± 0.49) × 10−6 (95 % confidence interval) and the corresponding absolute age of 4564.0 + 0.6/−0.7 Ma. Our new initial 53Mn/55Mn ratio is 26 ± 19 % higher than that obtained by a previous study for the same dolomite grain using a calcite standard. This difference is consistent with the difference between the RSF values of dolomite and calcite. Based on these results, we updated the initial 53Mn/55Mn ratio previously reported for dolomite in the Ryugu sample A0058 to be (3.21 ± 0.66) × 10−6, which corresponds to an absolute age of 4562.8 + 1.0/−1.2 Ma. This age seems to be the best estimate for the formation age of dolomite in Ryugu currently available.

Leaf age structures phyllosphere microbial communities in the field and greenhouse.

The structure of the leaf microbiome can alter host fitness and change in response to abiotic and biotic factors, like seasonality, climate, and leaf age. However, relatively few studies consider the influence of host age on microbial communities at a time scale of a few days, a short time scale relevant to microbes. To understand how host age modulates changes in the fungal and bacterial leaf microbiome on a short time scale, we ran independent field and greenhouse-based studies and characterized phyllosphere communities using next-generation sequencing approaches. Our field study characterized changes in the fungal and bacterial phyllosphere by examining leaves of different relative ages across individuals, whereas the greenhouse study examined changes in the fungal microbiome by absolute leaf age across individuals. Together, these results indicate that fungal communities are susceptible to change as a leaf ages as evidenced by shifts in the diversity of fungal taxa both in the field and the greenhouse. Similarly, there were increases in the diversity of fungal taxa by leaf age in the greenhouse. In bacterial communities in the field, we observed changes in the diversity, composition, and relative abundance of common taxa. These findings build upon previous literature characterizing host-associated communities at longer time scales and provide a foundation for targeted work examining how specific microbial taxa might interact with each other, such as fine-scale interactions between pathogenic and non-pathogenic species.