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Free, publicly-accessible full text available January 1, 2027
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Free, publicly-accessible full text available December 31, 2026
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Variability of oxygen isotopes in environmental water is recorded in tooth enamel, providing a record of seasonal change, dietary variability, and mobility. Physiology dampens this variability, however, as oxygen passes from environmental sources into blood and forming teeth. We showcase two methods of high resolution, 2-dimensional enamel sampling, and conduct modeling, to report why and how environmental oxygen isotope variability is reduced in animal bodies and teeth. First, using two modern experimental sheep, we introduce a sampling method, die-saw dicing, that provides high-resolution physical samples (n = 109 and 111 sample locations per tooth) for use in conventional stable isotope and molecular measurement protocols. Second, we use an ion microprobe to sample innermost enamel in an experimental sheep (n = 156 measurements), and in a Pleistocene orangutan (n = 176 measurements). Synchrotron and conventional μCT scans reveal innermost enamel thicknesses averaging 18 and 21 μm in width. Experimental data in sheep show that compared to drinking water, oxygen isotope variability in blood is reduced to 70–90 %; inner and innermost enamel retain between 36 and 48 % of likely drinking water stable isotope range, but this recovery declines to 28–34 % in outer enamel. 2D isotope sampling suggests that declines in isotopic variability, and shifted isotopic oscillations throughout enamel, result from the angle of secretory hydroxyapatite deposition and its overprinting by maturation. This overprinting occurs at all locations including innermost enamel, and is greatest in outer enamel. These findings confirm that all regions of enamel undergo maturation to varying degrees and confirm that inner and innermost enamel preserve more environmental variability than other regions. We further show how the resolution of isotope sampling — not only the spatial resolution within teeth, but also the temporal resolution of water in the environment — impacts our estimate of how much variation teeth recover from the environment. We suggest inverse methods, or multiplication by standard factors determined by ecology, taxon, and sampling strategy, to reconstruct the full scale of seasonal environmental variability. We advocate for combined inverse modeling and high-resolution sampling informed by the spatiotemporal pattern of enamel formation, and at the inner or innermost enamel when possible, to recover seasonal records from teeth.more » « lessFree, publicly-accessible full text available December 27, 2026
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Abstract For efficient roll-to-roll (R2R) production of flexible electronic components, a precise R2R transfer peeling process is essential, requiring accurate modeling and control. This paper introduces a novel approach to confining the dynamics of a nonlinear R2R mechanical peeling system within a convex set known as a norm-bounded linear differential inclusion (NLDI). This method utilizes constraints on uncertain system variables to create a tighter NLDI representation compared to other convexification techniques. Moreover, it offers drastically reduced computational cost compared to previous methods applied to convexify the R2R peeling system. The NLDI is employed to generate an H∞-optimal controller for the R2R peeling system, and both simulations and experiments demonstrate better dynamic performance compared to other controllers for R2R transfer.
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Abstract Background Additively-manufactured parts contain residual stresses induced by manufacturing. These residual stresses can be relaxed or redistributed by thermal loading. The presence of internal stress influences the dynamic response of parts, and this is of particular interest in thin plates subject to thermoacoustic loading in hypersonic vehicles and fusion reactors.
Objective To measure the changes in shape and modal frequencies caused by thermal loading of geometrically-reinforced thin plates that were additively manufactured in Inconel 625.
Methods Plates were additively-manufactured in landscape and portrait orientations using laser powder bed fusion. The plates were heated to a nominal temperature of 820 ̊C, which was expected to alleviate the residual stress from the build process. Pre- and post-heating, their modal frequencies were found experimentally and pulsed-laser stereo (3D) digital image correlation was used to evaluate their modal shapes. The resultant modal frequencies and shapes were compared with those from a subtractively-manufactured plate.
Results It was found that the heat cycle changed the shape of the plates relative to their as-manufactured state in addition to changing their natural frequencies and modal shapes.
Conclusions The change in shape induced by heating caused shifts in the natural frequencies and changes in the corresponding modal shapes. The results show quantitatively for the first time the important role that residual stresses can play in the dynamic response of geometrically-reinforced thin plates manufactured by additive and subtractive processes.
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Abstract Context Practitioners prefer to achieve performance without sacrificing productivity when developing scientific software. The Julia programming language is designed to develop performant computer programs without sacrificing productivity by providing a syntax that is scripting in nature. According to the Julia programming language website, the common projects are data science, machine learning, scientific domains, and parallel computing. While Julia has yielded benefits with respect to productivity, programs written in Julia can include security weaknesses, which can hamper the security of Julia-based scientific software. A systematic derivation of security weaknesses can facilitate secure development of Julia programs—an area that remains under-explored.
Objective The goal of this paper is to help practitioners securely develop Julia programs by conducting an empirical study of security weaknesses found in Julia programs.
Method We apply qualitative analysis on 4,592 Julia programs used in 126 open-source Julia projects to identify security weakness categories. Next, we construct a static analysis tool called
J uliaS taticA nalysisT ool (JSAT) that automatically identifies security weaknesses in Julia programs. We apply JSAT to automatically identify security weaknesses in 558 open-source Julia projects consisting of 25,008 Julia programs.Results We identify 7 security weakness categories, which include the usage of hard-coded password and unsafe invocation. From our empirical study we identify 23,839 security weaknesses. On average, we observe 24.9% Julia source code files to include at least one of the 7 security weakness categories.
Conclusion Based on our research findings, we recommend rigorous inspection efforts during code reviews. We also recommend further development and application of security static analysis tools so that security weaknesses in Julia programs can be detected before execution.
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ABSTRACT Scale‐Dependency of Native Status Classifying populations as native or nonnative requires well‐defined range boundaries for species. While many studies define native status according to large biogeographic realms, natural dispersal barriers often limit species distributions at regional or smaller spatial extents. As such, native/nonnative definitions are inherently scale‐dependent and estimates of community invadedness thus depend on the spatial resolution at which native status is defined. For example, nonnative species can be introduced among realms, among regions within realms, and among ecological provinces within regions (hereafter, simply “provinces”). By explicitly considering the scale‐dependency of native/nonnative status definitions, we can more effectively compare results across studies, more comprehensively evaluate the degree of invasion levels, and more objectively communicate the native status of a species.
Location 30,034 stream segments, conterminous United States.
Time Period 2000–2023.
Major Taxa Studied Freshwater fishes.
Quantifying Fish Community Invadedness Across<styled-content style='fixed-case'>US</styled-content>Streams We illustrate the importance of scale‐dependent native status definitions by quantifying nonnative species richness and relative abundance in stream fish communities across the United States, finding that provincially nonnative species are nearly four times as prevalent as extra‐realm nonnative species, and represented approximately 10% of all individuals in average community surveys.
Implications Unrealistically broad native status definitions underestimate community invadedness. Dismissing regionally and provincially nonnative species can have severe ecological consequences, including displacement and hybridisation with native species and the loss of unique communities through biotic homogenisation. These consequences may undermine efforts to maintain and protect distinct local biodiversity and conserve endemic species.
