Solar system chaos and the Paleocene-Eocene boundary age constrained by geology and astronomy

Astronomical calculations reveal the solar system's dynamical evolution, including its chaoticity, and represent the backbone of cyclostratigraphy and astrochronology. An absolute, fully calibrated astronomical time scale has hitherto been hampered beyond $\sim$50 Ma, because orbital calculations disagree before that age. Here we present geologic data and a new astronomical solution (ZB18a), showing exceptional agreement from $\sim$58 to 53 Ma. We provide a new absolute astrochronology up to 58 Ma and a new Paleocene-Eocene boundary age (56.01 $\pm$ 0.05 Ma). We show that the Paleocene-Eocene Thermal Maximum (PETM) onset occurred near a 405-kyr eccentricity maximum, suggesting an orbital trigger. We also provide an independent PETM duration (170 $\pm$ 30 kyr) from onset to recovery inflection. Our astronomical solution requires a chaotic resonance transition at $\sim$50 Ma in the solar system's fundamental frequencies.Comment: Supplementary materials available at this URL: www2.hawaii.edu/~zeebe/Astro.htm

Simple atomic quantum memory suitable for semiconductor quantum dot single photons

Quantum memories matched to single photon sources will form an important cornerstone of future quantum network technology. We demonstrate such a memory in warm Rb vapor with on-demand storage and retrieval, based on electromagnetically induced transparency. With an acceptance bandwidth of $\delta f$ = 0.66~GHz the memory is suitable for single photons emitted by semiconductor quantum dots. In this regime, vapor cell memories offer an excellent compromise between storage efficiency, storage time, noise level, and experimental complexity, and atomic collisions have negligible influence on the optical coherences. Operation of the memory is demonstrated using attenuated laser pulses on the single photon level. For 50 ns storage time we measure $\eta_{\textrm{e2e}}^{\textrm{50ns}} = 3.4(3)\%$ \emph{end-to-end efficiency} of the fiber-coupled memory, with an \emph{total intrinsic efficiency} $\eta_{\textrm{int}} = 17(3)\%$. Straightforward technological improvements can boost the end-to-end-efficiency to $\eta_{\textrm{e2e}} \approx 35\%$; beyond that increasing the optical depth and exploiting the Zeeman substructure of the atoms will allow such a memory to approach near unity efficiency. In the present memory, the unconditional readout noise level of $9\cdot 10^{-3}$ photons is dominated by atomic fluorescence, and for input pulses containing on average $\mu_{1}=0.27(4)$ photons the signal to noise level would be unity

Frequent grazing by sheep reduced caucasian clover cover and rhizome mass in ryegrass pasture

The responses of hexaploid caucasian clover (Trifolium ambiguum) to four contrasting grazing regimes were compared with those of white clover (T. repens) in an endophytic (Neotyphodium lolii) hybrid ryegrass pasture on a fertile lowland site. After 2 years, frequent grazing (set stocking) by sheep reduced caucasian clover cover to 10% compared with 25.5% in infrequent grazing (rotational grazing) treatments (mean spelling time 25 days). Similarly, frequent grazing reduced caucasian clover rhizome plus root dry weight (780 kg DM/ha when sampled to 100 mm depth in frequently grazed plots, compared with 3220 kg DM/ha for infrequent). Under frequent grazing treatments, mean white clover cover was 21%, under infrequent hard grazing it was 26% and under lax infrequent grazing it was 14%. The reduction in ryegrass tiller population from 5720/m² in the infrequently and laxly grazed treatments to 4150/ m² in the frequently hard grazed pastures indicated the severity of that hard grazed treatment. These results show that in lowland ryegrass pastures on high fertility sites, the stoloniferous growth form of white clover may be superior to the rhizomatous strategy of caucasian clover when grazing by sheep is frequent throughout spring, summer and autumn

Поліваріантний вплив біоактивної води Нафтуся на секрецію шлунка і пошкодження його слизової за умов перев’язки воротаря у щурів

Употребление крысами-самцами в течении 10-11 дней биоактивной воды Нафтуся вызывает в 72% случаев увеличение секреции кислоты желудком в условиях лигирования привратника. У 17% крыс кислотообразование не отличается от такового у контрольных животных, употреблявших водопроводную воду, а у 11% крыс констатирован кислотоингибиторный эффект биоактивной воды Нафтуся. Обнаружена инверсная связь между ацидогенезом и выделением гастрина в кровь и полость желудка, а также выраженностью язвенных повреждений его слизистой.The use rats-males in a flow 10-11 days of bioactive water Naftussya cause in 72% cases increase of secretion of acid by stomach in the conditions of ligating of pylorus. For 17% rats acid secretion does not differ from such for control animals, using a tapwater, and for 11% rats the inhibiting effect is established. Found out inverse relationship between acid secretion and secretion of gastrin in blood and cavity of stomach, and also expressed of ulcerous damages to his mucous membrane

Nitrogen fixation by caucasian clover and white clover in irrigated ryegrass pastures

The N₂ fixation ability of caucasian clover was compared with that of white clover in irrigated ryegrass pastures over years 2 and 3 of a grazing experiment, using the ¹⁵N enrichment technique. ‘Endura’ caucasian clover was inoculated with the specific Rhizobium strain ICC148. The N concentration in clover herbage and the proportion of clover N derived from N₂ fixation (PN) were similar for both clovers at averages of 4.6%N and 50–60% respectively over the 2 years. The amount of N₂ fixed per hectare was directly related to the amount of clover dry matter (DM) produced by the two clover species. Caucasian clover produced four times the DM yield of white clover in year 2 (5400 cf. 1450 kg DM/ha) and four times the amount of N₂ fixed in herbage (136 cf. 36 kg N/ ha). In year 3, caucasian clover produced 50% more clover DM (3450 cf. 2370 kg DM/ha) and N₂ fixed (98 cf. 66 kg N/ha) than white clover. The increased N input from caucasian clover increased grass %N and N uptake from soil in caucasian clover pastures resulting in higher total pasture production compared with white clover pastures (15.7 cf. 14.2 t DM/ha) by year 3. In this study, caucasian clover demonstrated greater potential than white clover to meet the N demands of high-yielding perennial ryegrass in an intensive pastoral system.The authors acknowledge funding from the Struthers Trust for the development of the grazing experiment at Lincoln University and FRST funding for provision of ¹⁶N and N analyses. We thank the C. Alma Baker and Struthers Trusts for providing A.D. Black with financial support from post-graduate scholarships

REMAP:An online remote sensing application for land cover classification and monitoring

Recent assessments of progress towards global conservation targets have revealed a paucity of indicators suitable for assessing the changing state of ecosystems. Moreover, land managers and planners are often unable to gain timely access to the maps they need to support their routine decision-making. This deficiency is partly due to a lack of suitable data on ecosystem change, driven mostly by the considerable technical expertise needed to develop ecosystem maps from remote sensing data. We have developed a free and open-access online remote sensing and environmental modelling application, the Remote Ecosystem Monitoring and Assessment Pipeline (Remap; https://remap-app.org), that enables volunteers, managers and scientists with little or no experience in remote sensing to generate classifications (maps) of land cover and land use change over time. Remap utilizes the geospatial data storage and analysis capacity of Google Earth Engine and requires only spatially resolved training data that define map classes of interest (e.g. ecosystem types). The training data, which can be uploaded or annotated interactively within Remap, are used in a random forest classification of up to 13 publicly available predictor datasets to assign all pixels in a focal region to map classes. Predictor datasets available in Remap represent topographic (e.g. slope, elevation), spectral (archival Landsat image composites) and climatic variables (precipitation, temperature) that are relevant to the distribution of ecosystems and land cover classes. The ability of Remap to develop and export high-quality classified maps in a very short (<10 min) time frame represents a considerable advance towards globally accessible and free application of remote sensing technology. By enabling access to data and simplifying remote sensing classifications, Remap can catalyse the monitoring of land use and change to support environmental conservation, including developing inventories of biodiversity, identifying hotspots of ecosystem diversity, ecosystem-based spatial conservation planning, mapping ecosystem loss at local scales and supporting environmental education initiatives

An artificial Rb atom in a semiconductor with lifetime-limited linewidth

We report results important for the creation of a best-of-both-worlds quantum hybrid system consisting of a solid-state source of single photons and an atomic ensemble as quantum memory. We generate single photons from a GaAs quantum dot (QD) frequency-matched to the Rb D2-transitions and then use the Rb transitions to analyze spectrally the quantum dot photons. We demonstrate lifetime-limited QD linewidths (1.48 GHz) with both resonant and non-resonant excitation. The QD resonance fluorescence in the low power regime is dominated by Rayleigh scattering, a route to match quantum dot and Rb atom linewidths and to shape the temporal wave packet of the QD photons. Noise in the solid-state environment is relatively benign: there is a blinking of the resonance fluorescence at MHz rates but negligible upper state dephasing of the QD transition. We therefore establish a close-to-ideal solid-state source of single photons at a key wavelength for quantum technologies