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Granular titanite from the Roter Kamm crater in Namibia:Product of regional metamorphism,not meteorite impact

Geoscience Frontiers 2022年第3期13卷 156-163页

作者： aaron j.Cavosie Christopher j.Spencer Noreen Evans Kai Rankenburg Robert j.Thomas Paul H.Macey Space Science and Technology Centre and The Institute for Geoscience Research School of Earth and Planetary ScienceCurtin UniversityPerthWA 6102Australia Dept.of Geological Sciences and Geological Engineering Queen’s UniversityOntarioCanada john de Laeter Centre Curtin UniversityPerthWA 6102Australia Council for Geoscience BellvilleWestern CapeSouth Africa

Accessory minerals with so-called granular texture have risen in importance as geochronological tools for U-Pb dating of meteorite impact events. Grain-scale recrystallization, typically triggered by a combination of high-strain deformation and post-impact heating, can create a polycrystalline microstructure consisting of neoblasts that expel radiogenic Pb, which are thus ideal for isotopic dating. While granular domains in zircon and monazite from shocked rocks have been demonstrated to preserve impact ages,few U-Pb dating studies have been conducted on granular microstructures in titanite(CaTiSiO;). Here we report the occurrence of granular-textured titanite from ~2020 Ma granite basement rock exposed in the rim of the 4–5 Ma Roter Kamm impact structure in Namibia. Orientation mapping reveals two microstructurally distinct titanite populations: one consisting of strained/deformed grains, and the other consisting of grains that comprise aggregates of strain-free neoblasts. In situ U-Pb geochronology on 37 grains shows that most grains from both titanite populations yield indistinguishable U-Pb dates of ca.1025 Ma, consistent with the observed microstructures forming during the Mesoproterozoic Namaqua Orogeny. Only four grains preserved older age domains, recording ca. 1875 Ma Paleoproterozoic metamorphism. Two significant observations emerge:(1) none of the analyzed titanite grains yield the 2020 Ma igneous crystallization age previously established from zircon in the same sample, and(2) no age-resetting was detected that could be attributed to the 4 to 5 Ma Roter Kamm impact *** the similarity of the neoblastic microstructure to minerals from other sites with an established impact provenance, the granular texture and near-complete Pb-loss in titanite from Roter Kamm granite instead records a Paleo-to Mesoproterozoic polymetamorphic history, rather than Miocene age shockrelated processes. These results highlight the critical importance of grain-scale cont

关键词： Namibia Roter Kamm Titanite EBSD Geochronology

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Incoherent excess noise spectrally encodes broadband light sources

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Light(Science & Applications) 2020年第1期9卷 358-366页

作者： aaron M.Kho Tingwei Zhang jun Zhu Conrad W.Merkle Vivek j.Srinivasan Department of Biomedical Engineering University of California DavisDavisCA 95616USA Department of Ophthalmology and Vision Science University of California Davis School of MedicineSacramentoCA 95817USA

Across optics and photonics,excess intensity noise is often considered a ***,we show that excess noise in broadband supercontinuum and superluminescent diode light sources encodes each spectral channel with unique intensity fluctuations,which actually serve a useful ***,we report that excess noise correlations can both characterize the spectral resolution of spectrometers and enable cross-calibration of their wavelengths across a broad *** to previous methods that use broadband interferometry and narrow linewidth lasers to characterize and calibrate spectrometers,our approach is simple,comprehensive,and rapid enough to be deployed during spectrometer ***,we employ this approach to aid alignment and reduce the depth-dependent degradation of the sensitivity and axial resolution in a spectrometer-based optical coherence tomography(OCT)system,revealing a new outer retinal ***,we achieve a pixel-to-pixel correspondence between two otherwise disparate spectrometers,enabling a robust comparison of their respective ***,excess intensity noise has useful applications in optics and photonics.

关键词： noise spectral optics

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Differences in pectoral fin spine morphology between vocal and silent clades of catfishes (Order Siluriformes): Ecomorphological implications

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Current Zoology 2010年第1期56卷 73-89页

作者： Ingrid M.KAATZ Donald j.STEWART aaron N.RjCE Phillip S.LOBEL Department of Environmental and Forest Biology SUNY College of Environmental Science and Forestry Department of Neurobiology and Behavior Cornell University Bioacoustics Research Program Cornell Laboratory of Ornithology Cornell University Department of Biology Boston University

Stridulatory sound-producing behavior is widespread across catfish families, but some are silent. To understand why, we compared spine morphology and ecotype of silent and vocal clades. We determined vocal ability of laboratory specimens during disturbance behavior. Vocal families had bony （not flexible or segmented） spines, well-developed anterior and/or posterior serrations, and statistically significantly longer spines. We compared morphology of the proximal end of the pectoral spine between vocal and silent species. For vocal taxa, microscopic rounded or bladed ridges or knobs were present on the dorsal process. Most silent species had reduced processes with exclusively smooth, convoluted, or honeycombed surfaces very similar to spine-locking surfaces, or they had novel surfaces （beaded, vacuolated, cobwebbed）. Most callichthyids had ridges but many were silent during disturbance. All doradid, most auchenipterid and most mochokid species were vocal and had ridges or knobs. Within the Auchenipteridae, vocal species had spines with greater weight and serration development but not length. Silent auchenipterids had thin, brittle, distally segmented spines with few microscopic serrations on only one margin and a highly reduced dorsal process lacking any known vocal morphology. Silent auchenipterids are derived and pelagic, while all vocal genera are basal and benthopelagic. This is the first phylogenetic evidence for stridulation mechanism loss within catfishes. Phylogenetic mapping of vocal ability, spine condition, and ecotype revealed the repeated presence of silence and vocal taxa, short and long spines, and ecotype shifts within clades. The appearance and loss of vocal behavior and supporting morphologies may have facilitated diversification among catfishes [Current Zoology 56 （1）： 73 89 2010].

关键词： Bioacoustic Defense mechanisms Historical biology Stridulation

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在非反刍动物饲料中运用单一组分外源性蛋白酶创造最优价值

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国外畜牧学（猪与禽） 2018年第1期38卷 65-67页

作者：兰慧(译) 邵建忠(校) aaron.j.cowieson Franz F.Roos 不详 DSM公司

外源性蛋白酶在过去15~20年中已经成为商用混合酶制剂的一部分,但仅在过去5~10年内才作为单一组分的商用酶——蛋白酶——上市。作为混合酶制剂的组成成分(通常还含有各种碳水化合物酶或糖酶和/或植酸酶),很难将各个组分成分的贡献分开... 详细信息

外源性蛋白酶在过去15~20年中已经成为商用混合酶制剂的一部分,但仅在过去5~10年内才作为单一组分的商用酶——蛋白酶——上市。作为混合酶制剂的组成成分(通常还含有各种碳水化合物酶或糖酶和/或植酸酶),很难将各个组分成分的贡献分开,同时每一种成分的功效具有隐性的价值而不是明确的价值。然而,单一组分酶制剂的攻效可以在不同的生产和营养条件下轻松地测定,并且它们与其他酶的互补性也很容易描述清楚。非反刍动物饲料添加外源性蛋白酶的动机是在保持动物生产性能的前提下显著降低饲料成本。这一目标通常是用给最低成本配方中的酶提供的营养基质替换日粮中昂贵的蛋白质/氨基酸源来实现的。最近的重点已经从这种经典的方法转向为蛋白酶应用中的所谓"额外蛋白(extra-proteinaceous)"效应,包括环境效益、垫料管理、肠道恢复力、均匀性和微生物稳定性。虽然这些"次要"效应可能并不是动物生产使用蛋白酶的主要动机,但它们越来越明显,且需要进行解释。此外,如果能够了解这些效应,那么它们可以主动转化成生产优势,如较低的饲料转化率和较高的日增重。本综述的目的是简要总结当前非反刍动物生产中单一组分外源性蛋白酶应用技术的现状,并提出可以解释"额外蛋白"效应的机制。最后将讨论可提高外源性蛋白酶对动物生产性能产生有益作用的日粮/动物因素。

关键词：蛋白酶蛋白质家禽猪氨基酸营养

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Arabidopsis FtsZ2-1 and FtsZ2-2 Are Functionally Redundant, But FtsZ-Based Plastid Division Is Not Essential for Chloroplast Partitioning or Plant Growth and Development

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Molecular Plant 2009年第6期2卷 1211-1222页

作者： aaron j. Schmitz jonathan M. Glynn Bradley j.S.C. Olson Kevin D. Stokes Katherine W. Osteryoung Department of Plant Biology 166 Plant Biology Bldg Michigan State University East Lansing MI 48824-1312 USA Cell and Molecular Biology Program Michigan State University East Lansing MI 48824 USA Department of Energy-Plant Research Laboratory Michigan State University East Lansing MI 48824 USA Genetics Program Michigan State University East Lansing MI 48824 USA Biochemistry and Molecular Biology Program Michigan State University East Lansing MI 48824 USA Present address: The Salk Institute for Biological Studies Plant Molecular and Cellular Biology Laboratory La Jolla CA 92037 USA Present address: Mycobacteria and Brucella Section NVSL/APHIS/USDA 1920 Dayton Ave Ames IA 50010 USA

FtsZ1 and FtsZ2 are phylogenetically distinct families of FtsZ in plants that co-localize to mid-plastid rings and facilitate division of chloroplasts. In plants, altered levels of either FtsZ1 or FtsZ2 cause dose-dependent defects in chloroplast division; thus, studies on the functional relationship between FtsZgenes require careful manipulation of FtsZ levels in vivo. To define the functional relationship between the two FtsZ2 genes in Arabidopsis thaliana, FtsZ2-1 and FtsZ2-2, we expressed FtsZ2-1 in an ftsZ2-2 null mutant, and vice versa, and determined whether the chloroplast division defects were rescued in plants expressing different total levels of FtsZ2. Full rescue was observed when either the FtsZ2-1 or FtsZ2-2 level approximated total FtsZ2 levels in wild-type （WT）. Additionally, FtsZ2-2 interacts with ARC6, as shown previously for FtsZ2- 1. These data indicate that FtsZ2-1 and FtsZ2-2 are functionally redundant for chloroplast division in Arabidopsis. To rigorously validate the requirement of each FtsZ family for chloroplast division, we replaced FtsZ1 with FtsZ2 in vivo, and vice versa, while maintaining the FtsZ level in the transgenic plants equal to that of the total level in WT. Chloroplast division defects were not rescued, demonstrating conclusively that FtsZ1 and FtsZ2 are non-redundant for maintenance of WT chloroplast numbers. Finally, we generated ftsZtriple null mutants and show that plants completely devoid of FtsZ protein are viable and fertile. As plastids are presumably essential organelles, these findings suggest that an FtsZ-independent mode of plastid partitioning may occur in higher plants.

关键词： Chloroplast plastid division FtsZ ARC6 PDV1.

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The role of decomposition reactions in assessing first-principles predictions of solid stability

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npj Computational Materials 2019年第1期5卷 1120-1128页

作者： Christopher j.Bartel Alan W.Weimer Stephan Lany Charles B.Musgrave aaron M.Holder Department of Chemical and Biological Engineering University of ColoradoBoulderCO 80309USA National Renewable Energy Laboratory GoldenCO 80401USA Department of Chemistry University of ColoradoBoulderCO 80309USA

The performance of density functional theory approximations for predicting materials thermodynamics is typically assessed by comparing calculated and experimentally determined enthalpies of formation from elemental phases,ΔH_(f).However,a compound competes thermodynamically with both other compounds and their constituent elemental forms,and thus,the enthalpies of the decomposition reactions to these competing phases,ΔH_(d),determine thermodynamic *** evaluated the phase diagrams for 56,791 compounds to classify decomposition reactions into three types:*** that produce elemental phases,*** that produce compounds,and *** that produce *** analysis shows that the decomposition into elemental forms is rarely the competing reaction that determines compound stability and that approximately two-thirds of decomposition reactions involve no elemental *** experimentally reported formation enthalpies for 1012 solid compounds,we assess the accuracy of the generalized gradient approximation(GGA)(PBE)and meta-GGA(SCAN)density functionals for predicting compound *** 646 decomposition reactions that are not trivially the formation reaction,PBE(mean absolute difference between theory and experiment(MAD)=70 meV/atom)and SCAN(MAD=59 meV/atom)perform similarly,and commonly employed correction schemes using fitted elemental reference energies make only a negligible improvement(~2 meV/atom).Furthermore,for 231 reactions involving only compounds(Type 2),the agreement between SCAN,PBE,and experiment is within~35 meV/atom and is thus comparable to the magnitude of experimental uncertainty.

关键词： stability stability solid

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Can a multistage approach improve individual tree mortality predictions across the complex mixed-species and managed forests of eastern North America?

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Forest Ecosystems 2023年第1期10卷 21-30页

作者： Cen Chen john Kershaw jr aaron Weiskittel Elizabeth McGarrigle Center for Research on Sustainable Forests University of MaineOronoME04469USA Faculty of Forestry&Environmental Management University of New BrunswickFrederictonNBE3B 5A3Canada Nova Scotia Department of Natural Resources HalifaxNSB3J 3M8Canada

Tree mortality plays a fundamental role in the dynamics of forest ecosystems,yet it is one of the most difficult phenomena to accurately *** modeling strategies have been developed to improve individual tree mortality *** less explored strategy is the use of a multistage modeling *** improvements from this approach have remained largely *** this study,we developed a novel multistage approach and compared its performance in individual tree mortality predictions with a more conventional approach using an identical individual tree mortality model *** permanent plot data(n=9442)covering the Acadian Region of North America and over multiple decades(1965–2014)were used in this *** results indicated that the model behavior with the multistage approach better depicted the observed mortality and showed a notable improvement over the conventional *** difference between the observed and predicted numbers of dead trees using the multistage approach was much smaller when compared with the conventional *** addition,tree survival probabilities predicted by the multistage approach generally were not significantly different from the observations,whereas the conventional approach consistently underestimated mortality across species and overestimated tree survival probabilities over the large range of DBH in the *** new multistage approach also predictions of zero mortality in individual plots,a result not possible in conventional ***,the new approach was more tolerant of modeling errors because it based estimates on ranked tree mortality rather than error-prone predicted ***,this new multistage approach deserves to be considered and tested in future studies.

关键词： Tree mortality modeling Mortality disaggregation Mixed effect model Annualization Mixed forests

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Factors affecting use of ballistics gelatin in laboratory studies of bacterial contamination in projectile wounds

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Military Medical Research 2018年第4期5卷 304-313页

作者： jessica j. Evans aaron Bost Karim H. Muci-Küchler Linda C. DeVeaux Biomedical Engineering Program South Dakota School of Mines and Technology Mechanical Engineering Department South Dakota School of Mines and Technology Department of Biology New Mexico Institute of Mining and Technology

Background: Ballistics gelatin is a common tissue surrogate used in bacterial contamination models for projectile wounds. Although these studies have demonstrated that bacteria are transferred from the surface of the gelatin to the wound track by a projectile, quantifiable results have been inconsistent and not repeatable in successive ***: In this study, five areas of a typical contamination model in which bacterial recovery or survival are affected were identified for optimization. The first was a contaminated "skin" surrogate, where the novel use of vacuum filtration of a bacterial culture and buffer onto filter paper was employed. The other possibly problematic areas of the bacterial distribution model included the determination of bacterial survival when the contamination model is dried, survival in solid and molten gelatin, and the effect of high-intensity lights used for recording high-speed ***: Vacuum filtration of bacteria and buffer resulted in a consistent bacterial distribution and recovery. The use of phosphate buffer M9(pH 7) aided in neutralizing the ballistics gelatin and improving bacterial survival in solid gelatin. Additionally, the use of high-intensity lights to record high-speed video and the use of a 42℃ water bath to melt the gelatin were found to be bactericidal for gram-positive and gram-negative ***: Multiple areas of a typical contamination model in which bacterial survival may be impeded were identified, and methods were proposed to improve survival in each area. These methods may be used to optimize the results of bacterial contamination models for medical applications, such as understanding the progression of infection in penetrating wounds and to identify possible sources of contamination for forensic purposes.

关键词： Ballistics gelatin Wound Contamination Bacterial model

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在非反刍动物饲料中运用单一组分外源性蛋白酶创造最优价值(续)

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国外畜牧学（猪与禽） 2018年第5期38卷 65-69页

作者：兰慧韩浩月 aaron j. cowieson Franz F. Roos(DSM)

2 对氨基酸消化率的影响二次曲线的实线显示最佳拟合曲线,虚线是95%的可信区间.水平的实线表示蛋白酶无作用（资料来自cowieson和Roos,2014）.

关键词：反刍动物饲料蛋白酶外源性价值组分氨基酸消化率拟合曲线二次曲线

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Alcohol-induced Wnt signaling inhibition during bone fracture healing is normalized by intermittent parathyroid hormone treatment

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Animal Models and Experimental Medicine 2020年第2期3卷 200-207页

作者： Esha M.Kapania Taylor jReif aaron Tsumura jonathan M。Eby john j.Callaci Internal Medicine-Pediatric Resident Rush University Medical CenterChicagoILUSA Limb Lengthening and Complex Reconstruction Fellowship Hospital for Special SurgeryNew YorkNYUSA Department of Orthopaedic Surgery and Rehabilitation Loyola University Medical CenterMaywoodILUSA Alcohol Research Program(ARP) Loyola University Chicago Stritch School of MedicineMaywoodILUSA

Nearly half of orthopaedic trauma patients are intoxicated at the time of injury, and excess alcohol consumption increases the risk for fracture nonunion. Previous studies show alcohol disrupts fracture associated Wnt signaling required for normal bone fracture repair. Intermittent parathyroid hormone(PTH) promotes bone growth through canonical Wnt signaling, however, no studies have investigated the effect of PTH on alcohol-inhibited bone fracture repair. Male C57 BL/6 mice received two-3 day alcohol binges separated by 4 days before receiving a mid-shaft tibia fracture. Postoperatively, mice received PTH daily until euthanasia. Wnt/β-catenin signaling was analyzed at 9 days post-fracture. As previously observed, acute alcohol exposure resulted in a >2-fold decrease in total and the active form of β-catenin and a 2-fold increase in inactive β-catenin within the fracture callus. Intermittent PTH abrogated the effect of alcohol on β-catenin within the fracture callus. Upstream of β-catenin, alcohol-treated animals had a 2-fold decrease in total LRP6, the Wnt co-receptor, which was restored with PTH treatment. Alcohol nor PTH had any significant effect on GSK-3β. These data show that intermittent PTH following a tibia fracture restores normal expression of Wnt signaling proteins within the fracture callus of alcohol-treated mice.

关键词： ethanol fracture callus parathyroid hormone Wnt signaling pathway

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