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A relational database of global U-Pb ages

Geoscience Frontiers 2018年第3期9卷 877-891页

作者： stephen j.puetz Progressive Science Institute HonoluluHI 96815USA

Enhanced understanding of how sampling techniques affect estimates of the global U-Pb age-distribution have, in turn, constrained U-Pb database design. Recent studies indicate that each continent has a unique age-distribution, as determined by zircon ages dated by the U-Pb isotope method. Likewise, broad regions within a continent also exhibit diverse age-distributions. To achieve a reliable estimate of the global distribution, the heterogenous composition of the continental crust requires sampling as many regions as feasibly possible. To attain this goal, and to provide a method for calculating age histograms, the records from a recent global U-Pb compilation are supplemented with 281,631 new records. These additions increase the database size to 700,598 records. In addition, the data are now restructured and made available as a relational database. After filtering the records by the six age-models included with the database, the results reveal two problems that might generally be unrecognized. First, an abrupt switch in the best-age at any given point(such as 1000 Ma) from ^(206)Pb/^(238)U ages to ^(207)Pb/^(206)Pb ages artificially depresses the age-distribution at the cutoff point. Second, rejecting analyses based on either absolute discordance or the magnitude of 2σ precision errors artificially depresses the age-distribution between 900 Ma and 2000 Ma. The results indicate that, when estimating the global U-Pb age-distribution, the methods for determining best-age and for rejecting records both require some attention. Possible solutions include using either an Accuracy Model or a Precision Model for estimating best-age, and then including all U-Pb records in the estimate, rather than rejecting any of them.

关键词： U-Pb age-distribution Histogram Global database Sampling Filtering Zircon

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Statistical analyses of Global U-Pb Database 2017

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Geoscience Frontiers 2018年第1期9卷 121-145页

作者： stephen j.puetz Carlos E.Ganade Udo Zimmermann Glenn Borchardt Progressive Science Institute HonoluluHI 96815USA Geological Survey of Brazil Rio de JaneiroBrazil University of Stavanger Department of Petroleum EngineeringStavangerNorway Progressive Science Institute Box 5335BerkeleyCA 94705USA

The method of obtaining zircon samples affects estimation of the global U-Pb age *** typically collect zircons via convenience sampling and cluster *** using these techniques,weight adjustments proportional to the areas of the sampled regions improve upon unweighted ***,grid-area and modern sediment methods are used to weight the samples from a new database of 418,967 U-Pb *** tests involve two age ***-1 uses the most precise U-Pb ages as the best ***-2 uses the^(206)Pb/^(238)U age as the best age if it is less than a1000 Ma cutoff,otherwise it uses the^(207)Pb/^(206)Pb age as the best age.A correlation analysis between the Model-1 and Model-2 ages indicates nearly identical distributions for both ***,after applying acceptance criteria to include only the most precise analyses with minimal discordance,a histogram of the rejected samples shows excessive rejection of the Model-2 analyses around the1000 Ma cutoff *** of the excessive rejection rate for Model-2,we select Model-1 as the preferred *** eliminating all rejected samples,the remaining analyses use only Model-1 ages for five rock-type subsets of the database:igneous,meta-igneous,sedimentary,meta-sedimentary,and modern ***,time-series plots,cross-correlation analyses,and spectral analyses determine the degree of alignment among the time-series and their *** all rock types,the U-Pb age distributions are similar for ages older than 500 Ma,but align poorly for ages younger than 500 *** similarities(>500 Ma)and differences(<500 Ma)highlight how reductionism from a detailed database enhances understanding of time-dependent sequences,such as erosion,detrital transport mechanisms,lithification,and ***-series analyses and spectral analyses of the age distributions predominantly indicate a synchronous period-tripling sequence of^91-Myr,~273-Myr,and^819-Myr among the various rock typ

关键词： Time series Spectral analysis Periodicity Sampling Reductionism Zircon

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The replication crisis and its relevance to Earth Science studies:Case studies and recommendations

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Geoscience Frontiers 2024年第4期15卷 304-314页

作者： stephen j.puetz Kent C.Condie Kurt Sundell Nick M.W.Roberts Christopher j.Spencer Slah Boulila Qiuming Cheng 475 Atkinson Dr Suite 704HonoluluHI 96814USA New Mexico Institute of Mining and Technology SocorroNM 87801USA Idaho State University PocatelloID 83209USA Geochronology and Tracers Facility British Geological SurveyKeyworthNottingham NG125GGUK Queen’s University Department of Geological Sciences and Geological EngineeringKingstonOntario K7L 3N6Canada Sorbonne Université CNRSInstitut des Sciences de la Terre ParisParisFrance State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesWuhan 430074China

Numerous scientific fields are facing a replication crisis,where the results of a study often cannot be replicated when a new study uses independent *** issue has been particularly emphasized in psychology,health,and medicine,as incorrect results in these fields could have serious consequences,where lives might be at *** other fields have also highlighted significant replication problems,the Earth Sciences seem to be an *** paucity of Earth Science research aimed at understanding the replication crisis prompted this ***,this work aims to fill that gap by seeking to replicate geological results involving various types of *** identify and discuss 11 key variables for replicating U-Pb age distributions:independent data,global sampling,proxy data,data quality,disproportionate non-random sampling,stratigraphic bias,potential filtering bias,accuracy and precision,correlating time-series segments,testing assumptions and divergent analytical methods,and analytical *** while this work primarily focuses on U-Pb age distributions,most of these factors(or variations of them)also apply to other geoscience ***,some of the discussions involve time-series consisting ofεHf,δ18O-zircon,14C,10Be,marineδ13C,and marineδ*** then provide specific recommendations for minimizing adverse effects related to these factors,and in the process enhancing prospects for replicating geological results.

关键词： Replication crisis Replicability Independent data Global time-series Globality index Filtered data

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Time series analysis of mantle cycles Part Ⅰ:Periodicities and correlations among seven global isotopic databases

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Geoscience Frontiers 2019年第4期10卷 1305-1326页

作者： stephen j. puetz Kent C. Condie Progressive Science Institute HonoluluHI96815USA New Mexico Institute of Mining and Technology SocorroNM87801USA

In this study,seven isotopic databases are presented and analyzed to identify mantle and crustal episodes on a global scale by focusing on periodicity ranging from 70 to 200 million years(Myr).The databases are the largest,or among the largest,compiled for each type of data-with an objective of finding some samples from every region of every continent,to make each database as global as conceivably *** databases contain zircon Lu/Hf isotopic data,whole-rock Sm/Nd isotopic data,U/Pb detrital zircon ages,U/Pb igneous zircon ages,U/Pb non-zircon ages,whole-rock Re/Os isotopic data,and large igneous province *** I of this study focuses on the periodicities of age histograms and geochemical averages developed from the seven databases,via spectral and cross-correlation *** physical cycles often propagate in exact integer multiples of a fundamental cycle,referred to as *** tests show that harmonic geological cycles of^93.5 and^187 Myr have persisted throughout terrestrial history,and the cyclicities are statistically significant for U/Pb igneous zircon ages,U/Pb detrital zircon ages,U/Pb zircon-rim ages,large igneous province ages,meanεHf(t)for all samples,meanεHf(t)values for igneous-only samples,and relative abundance of mafic *** important,cross-correlation analyses show these seven time-series are nearly synchronous(±7 Myr)with a model consisting of periodicities of 93.5 and 187 ***,the similarities between peaks in the 93.5 and 187 Myr mantle cycles and terminal ages of established and suspected superchrons provide a framework for predicting and testing superchron periodicity.

关键词： Zircon Database Isotope Statistical analysis Spectral analysis Cross correlation

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Time series analysis of mantle cycles Part Ⅱ:The geologic record in zircons, large igneous provinces and mantle lithosphere

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Geoscience Frontiers 2019年第4期10卷 1327-1336页

作者： Kent C. Condie stephen j. puetz Department of Earth & Environmental Science New Mexico Institute of Mining and TechnologySocorroNM87801USA Progressive Science Institute HonoluluHI96815USA

Igneous and detrital zircons have six major U/Pb isotopic age peaks in common(2700 Ma,1875 Ma.1045 Ma,625 Ma,265 Ma and 90 Ma).For igneous rocks,each age peak is comprised of subpeaks with distinct geographic distributions and a subpeak age range per age peak≤100 *** are eight major LIP age peaks(found on≥10 crustal provinces)of which only four are in common to major detrital zircon age peaks(2715 Ma,1875 Ma,825 Ma,90 Ma).Of the whole-rock Re depletion ages,58%have correspo nding detrital zircon age peaks and 55%have corresponding LIP age *** age pea ks are fou nd in common to igneous zircon,detrital zircon,LIP,and Re depletion age time series(3225 Ma,2875 Ma,2145 Ma,2085 Ma,1985 Ma,1785 Ma,1455 Ma,1175 Ma,825 Ma,and 90 Ma).and these are very robust peaks on a global scale as recorded in both crustal and mantle *** 50%of the age peaks in each of these time series correspond to predicted peaks in a 94-Myr mantle cycle,including four of the ten peaks in common to all four time series(2875 Ma,1785 Ma,825 Ma and 90 Ma).Age peak widths and subpeak ranges per age peak suggest that mantle events responsible for age peaks are2500 Ma),with the number of new provinces in which age peaks are represented decreasing with time within each *** breaks between the populations(at 2.5 Ga and 1 Ga)fall near the onsets of two transitions in Earth *** First Transition may represent a change from stagnant-lid tectonics into plate tectonics and the Second Transition,the onset of subduction of continental *** major factor controlling geographic distribution of age peaks is the changing locations of ***^2 Ga,age subpeaks and peaks are housed in orogens within or around the edges of crustal provinces,mostly in accretionary *** beginning at 1.9 Ga,collisional orogens become more *** coincidence in duration

关键词： Isotopic age peaks U/Pb zircon ages Re depletion ages Large igneous provinces Age peak correlation Mantle cycles

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Regional trends and petrologic factors inhibit global interpretations of zircon trace element compositions

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Geoscience Frontiers 2024年第5期15卷 300-307页

作者： Nick M.W.Roberts Christopher j.Spencer stephen puetz C.Brenhin Keller Simon Tapster Geochronology and Tracers Facility British Geological SurveyNottingham NG125GGUK Department of Geological Sciences and Geological Engineering Queen’s UniversityKingstonOntarioCanada 475 Atkinson Dr Suite 704HonoluluHI 96814USA Department of Earth Sciences Dartmouth CollegeHanoverNew HamphireUSA

The trace element composition of zircon reveals information about the melt that they are derived from,as such,detrital zircon trace element compositions can be used to interrogate melt compositions,and thus the evolution of the continental crust in time and ***,we present a global database of detrital zircon compositions and use it to test whether average global trends for five common petrogenetic proxies truly represent secular changes in continental *** demonstrate that the secular trend is broadly comparable across continental regions for Ti-in-zircon temperatures,but for other trace element ratios interrogated,secular trends are highly variable between continental *** trace element ratios result from multiple petrologic variables,we argue that these petrogenetic proxies can be overinterpreted if projected to global geologic *** particular,we caution against the interpretation of crustal thickness from trace elements in zircon,and we argue that our results negate current hypotheses concerning secular changes in crustal thickness.

关键词： Detrital zircon Trace elements Secular change Eu anomaly Crustal thickness

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Apples to oranges:environmentally derived,dynamic regulation of serotonin neuron subpopulations in adulthood?

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Neural Regeneration Research 2025年第9期20卷 2596-2597页

作者： Christopher j.O’Connell Matthew j.Robson Department of Genetics College of MedicineHarvard UniversityBostonMAUSA james L.Winkle College of Pharmacy Division of Pharmaceutical SciencesUniversity of CincinnatiCincinnatiOHUSA Neuroscience Graduate Program College of MedicineUniversity of CincinnatiCincinnatiOHUSA

Traumatic brain injury(TBI)is a public health problem with an undue economic burden that impacts nearly every age,ethnic,and gender group across the globe(Capizzi et al.,2020).TBIs are often sustained during a dynamic range of exposures to energetic environmental forces and as such outcomes are typically heterogeneous regarding severity and pathology(Capizzi et al.,2020).

关键词： sustained orange dynamic

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Gene therapy for spinal muscular atrophy:perspectives on the possibility of optimizing SMN1 delivery to correct all neurological and systemic perturbations

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Neural Regeneration Research 2025年第7期20卷 2011-2012页

作者： Sharon j.Brown Rafael j.Yáñez-Muñoz Heidi R.Fuller School of Pharmacy and Bioengineering Keele UniversityKeeleUK Wolfson Center for Inherited Neuromuscular Disease TORCH BuildingRJAH Orthopaedic HospitalOswestryUK *** Center of Gene and Cell TherapyDepartment of Biological SciencesSchool of Life Sciences and the EnvironmentRoyal Holloway University of LondonEghamUK

Spinal muscular atrophy(SMA)is a genetic condition that results in selective lower motor neuron loss with concomitant muscle weakness and *** genetic cause of SMA was understood in 1995 when loss or impairment of the survival motor neuron 1(SMN1)gene was identified as the main contributing factor(Lefebvre et al.,1995).This,in combination with the discovery that humans have a“back-up”gene,SMN2,which can produce low levels(approximately 10%)of the full-length functional SMN protein,has led to the generation of SMA-specific gene *** was traditionally classified according to age of symptom onset and developmental milestones achieved,with life expectancy and severity varying between ***,SMN2 copy number is used as a proxy for the prediction of disease severity,with higher SMN2 copy number typically being associated with reduced severity of SMA,although this relationship is not absolute:some individuals with low SMN2 copy number have less severe SMA phenotypes and vice ***,the etiology of SMA is further complicated by other factors,such as non-typical nucleotide variants and SMN2-independent modifiers of disease severity.

关键词： atrophy traditionally absolute

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Combining Aluminum Heat Treat with Hot Isostatic Pressing: A Comparison of Structure, Properties, and Processing Routes for a Cast AI-Si-Mg Alloy

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材料热处理学报 2004年第5期25卷 546-551页

作者： stephen j. Mashl Body cote HIP Inc. Andover Massachusetts USA

Bodycote researchers have successfully demonstrated that a T6 heat treatment can be integrated with Densal?, a proprietary, aluminum specific, hot isostatic pressing (HIP) process. In this combined operation, at least a portion of the solution heat treatment is conducted at elevated pressure. During development, two issues, adiabatic cooling during depressurization and a possible variation in the kinetics of homogenization resulting from conducting the solution heat treat at elevated pressure were perceived as factors which could alter the heat treat response from that seen in conventional processing. This paper reviews the results of experiments performed to Al-Si-Mg (A356.0) castings subjected to both combined and conventional processing routes. Results indicate that the combined HIP and heat treat process is an efficient means of achieving a microstructure characteristic of a conventionally T6 processed material while eliminating porosity within the casting. Further, the fatigue life of an A356.0 casting processed using the combined cycle can be improved by more than an order of magnitude over the as-cast and T6 treated component.

关键词： Al-Si-Mg合金热处理热等静压缩 HIP 机械性质疲劳寿命

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Women in visual neural regeneration research

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Neural Regeneration Research 2025年第2期20卷 489-490页

作者： Tonia S.Rex David j.Calkins Vanderbilt Eye Institute Vanderbilt University Medical CenterNashvilleTNUSA

The year 2024 marks the 60^(th)anniversary of Title IX and 25 years since the New York Times revealed bias against female faculty members at the Massachusetts Institute of *** take an opportunity here to examine the state of gender bias in a relatively new yet already prominent field,neural regeneration in the visual system,for which there is a well-defined context useful for this *** National Eye Institute(NEI)provided the first round of research funding for its Audacious Goals Initiative(AGI)on visual neural regeneration in 2013 and the last round in ***,we focus on this *** sources included PubMed,the National Science Foundation(NSF),the NEI,the Blue Ridge Institute for Medical Research and data from the major professional organization for eye and vision research,the Association for Research in Vision and Ophthalmology(ARVO).

关键词： neural visual Times

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