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1. Influence of ammonia oxidation rate on thaumarchaeal lipid composition and the TEX ₈₆ temperature proxy

   https://doi.org/10.1073/pnas.1518534113  

   Hurley, Sarah J.; Elling, Felix J.; Könneke, Martin; Buchwald, Carolyn; Wankel, Scott D.; Santoro, Alyson E.; Lipp, Julius Sebastian; Hinrichs, Kai-Uwe; Pearson, Ann (July 2016, Proceedings of the National Academy of Sciences)
2. Impacts of Paleoecology on the TEX ₈₆ Sea Surface Temperature Proxy in the Pliocene‐Pleistocene Mediterranean Sea

   https://doi.org/10.1029/2018PA003494  

   Polik, Catherine A.; Elling, Felix J.; Pearson, Ann (December 2018, Paleoceanography and Paleoclimatology)

   Abstract The TEX₈₆proxy, based on the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs) from planktonic Thaumarchaeota, is widely used to reconstruct sea surface temperature (SST). Recent observations of species‐specific and regionally dependent TEX₈₆‐SST relationships in cultures and the modern ocean raise the question of whether nonthermal factors may have impacted TEX₈₆paleorecords. Here we evaluate the effects of ecological changes on TEX₈₆using one Pliocene and two Pleistocene sapropels from the Mediterranean Sea. We find that TEX₈₆‐derived SSTs deviate from‐derived SSTs before, during, and after each sapropel event.‐derived SSTs vary by less than 6 °C, while TEX₈₆‐derived SSTs vary by up to 15 °C within a single record. Compound‐specific carbon isotope compositions indicate minimal confounding influence on TEX₈₆from exogenous sources. Some of the variation can be accounted for by changes in nitrogen cycling intensity affecting thaumarchaeal iGDGT biosynthesis, as demonstrated by an inverse relationship between TEX₈₆and δ¹⁵N_TN. TEX₈₆‐derived SSTs also consistently show warm anomalies in the Pleistocene, while the Pliocene samples exhibit both warmer and cooler relative offsets. These anomalies result from systematic differences between Plio‐Pleistocene iGDGT distributions and both modern Mediterranean and modern, globally distributed core top samples. Through characteristic GDGT distributions, we suggest the existence of three distinct endemic populations of Thaumarchaeota in the Pliocene, Pleistocene, and modern Mediterranean Sea, respectively. Importantly, these communities prevailed during both sapropel and oligotrophic conditions. Our results demonstrate that ecological and community‐specific effects must be considered when applying the TEX₈₆proxy to paleorecords. 

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3. Comparison of Late Neogene U ^k′ ₃₇ and TEX ₈₆ Paleotemperature Records From the Eastern Equatorial Pacific at Orbital Resolution

   https://doi.org/10.1029/2020PA003858  

   Lawrence, K. T.; Pearson, A.; Castañeda, I. S.; Ladlow, C.; Peterson, L. C.; Lawrence, C. E. (June 2020, Paleoceanography and Paleoclimatology)

   Abstract Key features of late Neogene climate remain uncertain due to conflicting records derived from different sea surface temperature (SST) proxies. To understand scenarios in which proxy‐derived temperature estimates can be used interchangeably or are instead measuring different aspects of the same system, it is necessary to explore both the consistencies and differences between specific paleothermometers. Here, we report orbital‐scale climate records from ODP Site 846 in the eastern equatorial Pacific (EEP) for the interval from ~5–6 Ma using alkenone and archaeal lipid paleothermometers. Results from both proxies are similar in their secular trends and magnitude of long‐term temperature change, and spectral analysis demonstrates that the records are coherent and in‐phase in both the obliquity and precession bands. However, we find that the temperatures reconstructed by TEX₈₆are consistently offset toward colder values by ~2 °C relative to U^k′₃₇‐derived temperatures in global calibrations, or by ~0.8 °C in Bayesian‐based calibrations. All combinations of calibrations also yield approximately twice the amplitude of orbital‐scale variation in TEX₈₆relative to U^k′₃₇‐derived temperature fluctuations. Both temperature proxies are negatively correlated with sedimentary alkenone concentrations, which we use as an indicator of increased export productivity. Removing this productivity contribution from TEX₈₆results in an adjusted TEX₈₆record with temperature sensitivity identical to U^k′₃₇. In future applications, this signal may be decoupled using additional sedimentary indicators of paleoproductivity, which likely will be most important for upwelling zone environments. There remain other nonexplained factors that contribute to differences between TEX₈₆and U^k′₃₇that warrant additional investigation. 

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4. $$\beta$$ -Ga ₂ O ₃ NEMS Oscillator for Real-Time Middle Ultraviolet (MUV) Light Detection

   https://doi.org/10.1109/LED.2018.2850776  

   Zheng, Xu-Qian; Lee, Jaesung; Rafique, Subrina; Karim, Md Rezaul; Han, Lu; Zhao, Hongping; Zorman, Christian A.; Feng, Philip X.-L. (August 2018, IEEE Electron Device Letters)
5. YBa $$_2$$ Cu $$_3$$ O $$_{7-\delta }$$ -CeO $$_2$$ -YBa $$_2$$ Cu $$_3$$ O $$_{7-\delta }$$ Multilayers Grown by Reactive Co-Evaporation on Sapphire Wafers

   https://doi.org/10.1109/TASC.2019.2898778  

   Wang, Yan-Ting; Semerad, Robert; McCoy, Stephen J.; Cai, Han; LeFebvre, Jay; Grezdo, Holly; Cho, Ethan Y.; Li, Hao; Cybart, Shane A. (August 2019, IEEE Transactions on Applied Superconductivity)