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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. 

World-scale augmented reality (AR) applications need a ubiquitous 6DoF localization backend to anchor content to the real world consistently across devices. Large organizations such as Google and Niantic are 3D scanning outdoor public spaces in order to build their own Visual Positioning Systems (VPS). These centralized VPS solutions fail to meet the needs of many future AR applications---they do not cover private indoor spaces because of privacy concerns, regulations, and the labor bottleneck of updating and maintaining 3D scans. In this paper, we present OpenFLAME a federated VPS backend that allows independent organizations to 3D scan and maintain a separate VPS service for their own spaces. This enables access control of indoor 3D scans, distributed maintenance of the VPS backend, and encourages larger coverage. Sharding of VPS services introduces several unique challenges---coherency of localization results across spaces, quality control of VPS services, selection of the right VPS service for a location, and many others. We introduce the concept of federated image-based localization and provide reference solutions for managing and merging data across maps without sharing private data. 

We report on the design and performance of an improved duoplasmatron ion source for secondary ion mass spectrometers. The source is designed specifically to optimize extraction of negative oxygen ions while suppressing electron extraction using a built-in magnetic asymmetry in the anode electrode. Other changes from conventional designs are (a) drilling the ion extraction aperture directly into the magnetic steel anode rather than in a refractory (nonmagnetic) metal insert, thereby eliminating a magnetic “hole” that acts to counter the desired magnetic concentration of the discharge at the aperture and (b) forming the anode into a conical shape convex toward the intermediate electrode to increase the magnetic field concentration at the extraction aperture, hence the term “Canode.” The built-in magnetic asymmetry allows the width and shape of the intermediate electrode to be varied to further optimize magnetic concentration of the discharge. Tests were performed with both ims 6f and NanoSIMS 50L instruments manufactured by Cameca Instruments, Inc. (Fitchburg, WI, USA). In the ims 6f, the Canode design gave O− primary ion currents up to a factor of five greater than the factory ion source design. In the NanoSIMS 50L, the Canode source produced a focused O− ion beam at the sample with a diameter of 50 nm, identical to the performance of the radio-frequency Hyperion ion source developed by Oregon Physics (Beaverton, OR, USA) and offered as an option by Cameca. 

Formation of C-N bonds is a quintessential transformation in organic synthesis. Among the various methods to access them, hydrogen borrowing catalysis offers a green, atom economical, and cost-effective approach with water as the sole by-product. In this reaction, amines are alkylated with alcohol coupling partners in the presence of a transition metal catalyst. Several catalytic systems have been developed and employed in the synthesis of pharmaceutical intermediates and complex natural products, replacing conventional amination reactions with hydrogen borrowing reactions that deliver improved selectivity and yield. In this short review, we compare hydrogen borrowing N-alkylation with other classical and modern C-N bond forming reactions and discuss applications in pharmaceutical synthesis. 

Marine gateways play a critical role in the exchange of water, heat, salt, and nutrients between oceans and seas. Changes in gateway geometry can significantly alter both the pattern of global ocean circulation and climate. Today, the volume of dense water supplied by Atlantic–Mediterranean exchange through the Gibraltar Strait is among the largest in the global ocean. For the past 5 My, this overflow has generated a saline plume at intermediate depths in the Atlantic that deposits distinctive contouritic sediments and contributes to the formation of North Atlantic Deep Water. This single gateway configuration only developed in the Early Pliocene. During the Miocene, two narrow corridors linked the Mediterranean and Atlantic: one in northern Morocco and the other in southern Spain. Progressive restriction and closure of these corridors resulted in extreme salinity fluctuations in the Mediterranean and the precipitation of the Messinian Salinity Crisis salt giant. International Ocean Discovery Program (IODP) Expedition 401 is the offshore drilling component of a Land-2-Sea drilling proposal, Investigating Miocene Mediterranean–Atlantic Gateway Exchange (IMMAGE). Its aim is to recover a complete record of Atlantic–Mediterranean exchange from its Late Miocene inception to its current configuration by targeting Miocene offshore sediments on either side of the Gibraltar Strait. Miocene cores from the two precursor connections now exposed on land will be obtained by future International Continental Scientific Drilling Program (ICDP) campaigns. 

This is a summary of major ion concentrations for stream water samples collected at the outflow of the Saddle stream, near Saddle grid point 007 on Niwot Ridge.