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Past North African humid periods caused expanded vegetation over the Sahara, due to northward tropical African rainbelt displacement, opening migration pathways for hominins. Commonly, these precession-timed humid periods ended within 15,000 years due to rainbelt retreat. During North African humid periods, eastern Mediterranean organic-rich layers called sapropels were deposited at least since 8 Myr. Here we combine climate modelling with palaeoclimate proxy data to show that weakened sapropel preservation during the 5.3–3.3 Myr period resulted from nutrient runoff limitation associated with enhanced North African vegetation cover due to a persistently more northward-located African monsoon front, relative to the mid-Pliocene (3.3–3.0 Myr, when glacial intensity increased). Moreover, sapropel absence within the 3.8–3.3 Myr period coincided with maximum monsoon runoff and extensively humid, vegetated conditions throughout North Africa. Our model results indicate that this 0.5-Myr-long pan-North African humid period ended at ~3.3 Myr because of southward monsoon front displacement with Northern Hemisphere glacial intensification. The 3.8–3.3 Myr humid period coincided with the earliest known evidence for hominin coexistence over eastern and central North Africa. We posit that persistent green corridors during this humid phase facilitated early hominin connectivity and migration, expanding their habitat range over the wider North African territory.

MARY TOFT;Or, The Rabbit QueenBy Dexter Palmer In 1726, in Godalming, England, Mary Toft ''gave birth'' to bits of a rabbit. Those scare quotes embrace the heart of Dexter Palmer's [...]

Paleoclimate proxy records from regions sensitive to humidity/aridity extremes provide crucial insights into the natural forcing mechanisms underlying long‐term climate variability in broader regions. One such area is Northwest Australia, where the Australian monsoon impacts its northernmost fringes, which are bordered by the Great Sandy Desert inland. Marine sediments from the Australian Northwest Shelf record fluvial run‐off and eolian dust input during the wet and dry seasons, respectively. The location is therefore ideal for investigating long‐term variability in the Australian monsoon and Northwest Australian dust flux over orbital timescales. However, there are few continuous, high‐resolution paleoclimate records from this region spanning the early Pleistocene, when strong ice‐climate feedbacks of the late Pleistocene did not yet dominate global climate. Here, we present geochemical and environmental magnetic proxy records that reveal %CaCO3and dust‐flux variability between 2.9 and 1.6 million years (Myr) ago from International Ocean Discovery Program Expedition 356 Site U1464 on the Australian Northwest Shelf. We establish a new, orbitally‐tuned chronology for Site U1464, primarily based on ∼400 thousand year (kyr) eccentricity cyclicity in %CaCO3, and observe strong obliquity variability (41 and 54 kyr periodicities) but almost no precession signal in the dust‐flux records. We propose that the 41 kyr cycle in Northwest Australian dust flux could be a linear response to East Asian winter monsoon intensity and/or the summer inter‐tropical insolation gradient (SITIG), whereas the 54 kyr cyclicity might be a non‐linear response to obliquity amplitude modulation via the SITIG effect on the cross‐equatorial atmospheric circulations. This study establishes a new orbitally‐constrained chronology for International Ocean Discovery Program Site U1464Australian Northwest shelf sediments preserve ∼400 kyr eccentricity cycles in %CaCO3and ∼41 kyr obliquity cycles in dust proxy recordsObliquity in Northwest Australian dust flux may be related to the East Asian winter monsoon and summer inter‐tropical insolation gradient This study establishes a new orbitally‐constrained chronology for International Ocean Discovery Program Site U1464 Australian Northwest shelf sediments preserve ∼400 kyr eccentricity cycles in %CaCO3and ∼41 kyr obliquity cycles in dust proxy records Obliquity in Northwest Australian dust flux may be related to the East Asian winter monsoon and summer inter‐tropical insolation gradient

CITY OF CROWSBy Chris Womersley352 pp. Europa Editions. $17 By 1673, the year in which ''City of Crows'' is set, the papal bull officially recognizing the existence of witches had [...]

GRACE By Paul Lynch 354 pp. Little, Brown & Company. $26. To twist a phrase from P. G. Wodehouse, it's not difficult to tell the difference between Paul Lynch's writing [...]

A WANT OF KINDNESSBy Joanne Limburg435 pp. Pegasus Books. $25.95. My first encounter with Queen Anne was in the epilogue to Antonia Fraser's ''Mary Queen of Scots.'' During a search [...]

A mile-high marine cascade terminated the Messinian salinity crisis 5.33 Myr ago, due to partial collapse of the Gibraltar sill that had isolated a largely desiccated Mediterranean from the Atlantic Ocean. Atlantic waters may have refilled the basin within 2 years. Prevailing hypotheses suggest that normal marine conditions were established across the Mediterranean immediately after the catastrophic flooding. Here we use proxy data and fluid physics-based modelling to show that normal conditions were likely for the western Mediterranean, but that flooding caused a massive transfer of salt from the western to the eastern Mediterranean across the Sicily sill, which became a hyper-salinity-stratified basin. Hyper-stratification inhibited deep-water ventilation, causing anomalously long-lasting organic-rich (sapropel) sediment deposition. Model data agreement indicates that hyper-stratification breakdown by diapycnal diffusion required 26,000 years. An alternative hypothesis that Atlantic reconnection occurred after the Mediterranean had largely been refilled is inconsistent with our observations, as this would have led to hyper-stratification and sapropel formation in both basins. Our findings offer insight into the role of stratification in delaying the re-establishment of normal marine conditions following abrupt refilling of a previously desiccated ocean basin.

MARGARET THE FIRSTBy Danielle Dutton167 pp. Catapult. Paper, $15.95. When, in the winter of 1673, Margaret Cavendish, Duchess of Newcastle, was found dead in a garden chair, her husband lost [...]

THE FAIR FIGHT By Anna Freeman 474 pp. Riverhead Books. $27.95. Writing any novel involves decisions. In historical novels, these decisions can be agonizing, since readers of this genre are [...]

Organic‐rich sapropel layers punctuate the eastern Mediterranean sedimentary sequence, recording deep‐sea anoxic events. The timing of sapropel deposition coincides with precession minima, which are associated with the northward migration of the monsoon rain belt over North Africa. The resultant increase in monsoon precipitation over the Sahara caused an increase in low‐δ18O freshwater runoff into eastern Mediterranean surface waters, which is reflected by negative δ18O anomalies in the records of planktic foraminiferal calcite. However, despite extensive research on sapropels, the magnitude of monsoon intensification and freshwater runoff, along with its influence on δ18O, remains elusive. Here, we present a quantification of African monsoon freshwater runoff into the eastern Mediterranean for the period of deposition of last interglacial sapropel S5 (~128.3–121.5 ka). Our method uses a box model of the Mediterranean Sea, which represents different water masses, and has been calibrated using δ18O from planktic foraminiferal species of different depth and seasonal habitats. The model was constrained with existing records of sea level and sea surface temperature then inverted to deconvolve the δ18O signal of the surface‐dwelling foraminiferal species Globigerinoides ruber(w) and calculate the freshwater runoff volume. Our calculated African monsoon runoff suggests large increases in freshwater discharge to the eastern Mediterranean (up to ~8.8 times the modern pre‐Aswan Nile discharge). Rapid onset of S5 deposition following the estimated increase in runoff strongly suggests a preconditioning of the eastern Mediterranean for sapropel deposition. Our study also provides insight into the stratification and warming of eastern Mediterranean surface waters during the S5 interval. We present a quantitative time series estimate of North African monsoon intensification for the interval of sapropel S5 depositionSea level and sea surface temperature records used to deconvolve eastern Mediterranean planktic foraminiferal stable oxygen isotope signalPreconditioning of the eastern Mediterranean for sapropel deposition suggested by rapid onset of S5 following increase in African runoff

The results demonstrate that coronary CT angiography–derived fractional flow reserve using machine learning performs equally to computational fluid dynamics modeling in detecting lesion-specific ischemia; both algorithms outperform coronary CT angiography alone and quantitative coronary angiography.

Global ice volume (sea level) and deep‐sea temperature are key measures of Earth's climatic state. We synthesize evidence for multi‐centennial to millennial ice‐volume and deep‐sea temperature variations over the past 40 million years, which encompass the early glaciation of Antarctica at ∼34 million years ago (Ma), the end of the Middle Miocene Climate Optimum, and the descent into bipolar glaciation from ∼3.4 Ma. We compare different sea‐level and deep‐water temperature reconstructions to build a resource for validating long‐term numerical model‐based approaches. We present: (a) a new template synthesis of ice‐volume and deep‐sea temperature variations for the past 5.3 million years; (b) an extended template for the interval between 5.3 and 40 Ma; and (c) a discussion of uncertainties and limitations. We highlight key issues associated with glacial state changes in the geological record from 40 Ma to present that require attention in further research. These include offsets between calibration‐sensitive versus thermodynamically guided deep‐sea paleothermometry proxy measurements; a conundrum related to the magnitudes of sea‐level and deep‐sea temperature change at the Eocene‐Oligocene transition at 34 Ma; a discrepancy in deep‐sea temperature levels during the Middle Miocene; and a hitherto unquantified non‐linear reduction of glacial deep‐sea temperatures through the past 3.4 million years toward a near‐freezing deep‐sea temperature asymptote, while sea level stepped down in a more uniform manner. Uncertainties in proxy‐based reconstructions hinder further distinction of “reality” among reconstructions. It seems more promising to further narrow this using three‐dimensional ice‐sheet models with realistic ice‐climate‐ocean‐topography‐lithosphere coupling, as computational capacities improve. Global ice volume (hence, sea level) and deep‐sea temperature are important measures of Earth's climatic state. To better understand Earth's climate cycles in response to its orbitally driven insolation cycles, we evaluate and synthesize evidence for ice‐volume (sea‐level) and deep‐sea temperature variations at multi‐centennial to millennial resolution throughout the last 40 million years. These last 40 million years encompass the major build‐up of Antarctic glaciation from about 34 million years ago, and development of extensive Northern Hemisphere ice sheets from about 3.4 million years ago. We present a new template synthesis of ice‐volume (sea‐level) and deep‐sea temperature for the past 5.3 million years, with extension through the interval between 5.3 and 40 Ma with wider uncertainties. We also highlight a number of remaining questions about major climate transitions, including the early glaciation history of Antarctica, the end of the so‐called Middle Miocene Climate Optimum from about ∼14.5 Ma, and the descent over the past several million years into conditions with extensive ice‐age maxima in both hemispheres. New synthesis of sea level and deep‐sea temperature over 40 million years, at millennial resolution, across seven different methodsDiscrepancies between Eocene‐Oligocene and Middle Miocene sea‐level reconstructions are highlighted for focussed future researchPlio‐Pleistocene glacial deep‐sea temperature asymptoted to a freezing limit by ∼1.25–0.9 Ma; glacial sea‐level minima decreased ∼linearly New synthesis of sea level and deep‐sea temperature over 40 million years, at millennial resolution, across seven different methods Discrepancies between Eocene‐Oligocene and Middle Miocene sea‐level reconstructions are highlighted for focussed future research Plio‐Pleistocene glacial deep‐sea temperature asymptoted to a freezing limit by ∼1.25–0.9 Ma; glacial sea‐level minima decreased ∼linearly

There is an urgent need to develop new protocols to reduce radiation dose of coronary computed tomography angiography (CTA). The aim of this pilot study was to demonstrate the feasibility of an ultra-low dose CTA scanning.

One method to acquire dual-energy (DE) computed tomography (CT) data is to perform CT scans at 2 different x-ray tube voltages, typically 80 and 140 kV, either as 2 separate scans, by means of rapid kV switching, or with the use of 2 x-ray sources as in dual-source CT (DSCT) systems. In DSCT, it is possible to improve spectral separation with tin prefiltration (Sn) of the high-kV beam. Recently, x-ray tube voltages beyond the established range of 80 to 140 kV were commercially introduced, which enable additional voltage combinations for DE acquisitions, such as 80150 Sn or 90150 Sn kV. Here, we investigate the DE performance of several x-ray tube voltages and prefilter combinations on 2 DSCT scanners and the impact of the spectra on quantitative analysis and dose efficiency.

Following the trend of low-radiation dose computed tomographic (CT) imaging, concerns regarding the detectability of low-contrast lesions have been growing. The goal of this research was to evaluate whether a new image-based algorithm (Mono) for virtual monoenergetic imaging with a dual-energy CT scanner can improve the contrast-to-noise ratio (CNR) and conspicuity of these low-contrast objects when using iodinated contrast media.

Periodic and marked redox changes in eastern Mediterranean marine sediments drive environmental and diagenetic changes to which magnetic minerals are sensitive. Magnetic property changes, therefore, provide useful indications of paleoceanographic conditions during and after periods of organic‐rich sediment (sapropel) deposition. Magnetic properties of eastern Mediterranean sediments at room temperature have been studied for decades; however, few studies have considered low‐temperature magnetic properties. Here, we investigate the low‐temperature (10–300 K) magnetic properties of different eastern Mediterranean sediment types combined with room temperature (∼300 K) magnetic properties, transmission electron microscopy, and calibrated X‐ray fluorescence elemental data to illustrate the valuable information that can be obtained from low‐temperature magnetic analysis of sediments. Our low‐temperature magnetic results suggest that magnetite magnetofossils and superparamagnetic (SP) particles occur widely in eastern Mediterranean sediments. SP particle contents are highest in diagenetically reduced intervals associated with sapropels. In contrast, magnetite magnetofossils are most abundant in oxidation fronts at the tops of sapropels, where strong redox gradients formed, but are also widespread throughout other sedimentary intervals that have not been subjected to extensive reductive diagenesis. Moreover, the surfaces of magnetite particles are maghemitized (i.e., partially oxidized) in oxidation fronts at the tops of sapropels, and in other oxic sediment intervals. Our results demonstrate the value of LT magnetic measurements for quantifying diverse sedimentary magnetic signals of interest in environmental magnetism when studying paleoceanographic and paleoenvironmental processes. Magnetic minerals are sensitive to environmental changes. Investigating their variations through sedimentary sequences can provide information about ancient environmental and climatic changes. Room temperature magnetic properties are widely measured in environmental magnetism, while low‐temperature (LT) magnetic properties that are measured between room temperature and ∼10 K are studied much less, even though they can provide useful information about the presence of particular magnetic minerals and their particle size distributions. We present extensive LT analyses of Mediterranean marine sediments, together with room temperature magnetic, transmission electron microscope, and calibrated X‐ray fluorescence elemental analyses to discuss redox changes of magnetic minerals within organic‐rich sediment intervals to quantify these diverse magnetic particle types. Our LT results suggest that the fossilized remains of magnetotactic bacteria and tiny superparamagnetic particles occur widely in eastern Mediterranean sediments, and that the surfaces of magnetite particles are widely oxidized and provide a measure of sedimentary oxidation variations. This work demonstrates that LT magnetic measurements can be used to quantify diverse sedimentary magnetic signals, and will be widely applicable in paleoenvironmental magnetic research. Low‐temperature magnetic properties of eastern Mediterranean sediments enable quantification of magnetic particle typesMagnetofossils and superparamagnetic particles exist widely in eastern Mediterranean sedimentsMaghemitization is widespread in oxic sediment intervals and provides a measure of oxidation variations Low‐temperature magnetic properties of eastern Mediterranean sediments enable quantification of magnetic particle types Magnetofossils and superparamagnetic particles exist widely in eastern Mediterranean sediments Maghemitization is widespread in oxic sediment intervals and provides a measure of oxidation variations

Eolian mineral dust is an active agent in the global climate system. It affects planetary albedo and can influence marine biological productivity and ocean‐atmosphere carbon dynamics. This makes the understanding of the global dust cycle crucial for constraining the dust/climate relationship, which requires long‐term dust emission records for all major dust sources. Despite their importance, the sources of atmospheric dust deposited in the Southern Ocean remain poorly constrained. Eolian dust in the Pacific sector of the Southern Ocean is generally assumed to originate from Australia, with minor contributions from New Zealand. Here, we present a high‐resolution elemental record of terrestrial inputs for the past ∼410 kyr from marine sediment core PS75/100‐4 recovered from east of South Island, New Zealand. Sediment grain size is slightly finer than that of loess deposits from South Island, New Zealand, and is coarser than that of marine sediments in the Tasman Sea to the west of New Zealand, which indicates that the dust originated mainly from New Zealand and not only from Australia. Core PS75/100‐4 records lithogenic mass accumulation rates ranging from ∼0.01 to 0.69 g/cm2/kyr (∼0.20 g/cm2/kyr average), with variations over a factor of ∼3–4 over glacial versus interglacial timescales for the past 410 kyr. Our geochemical data correlate well with the Southern Ocean and Antarctic eolian dust records and suggest a westerly wind‐supplied dust signal from New Zealand. Our findings, therefore, suggest that New Zealand should be considered an important long‐term regional dust source in global dust cycle models. We present an SW Pacific Ocean lithogenic flux record for the last 410 ka that covaries with the Antarctic and sub‐Antarctic dust recordsWesterly wind‐transported material from New Zealand is the most likely dust source over glacial‐interglacial cyclesSilt‐sized sediment was well sorted by bottom currents, which were more energetic in interglacials than glacials We present an SW Pacific Ocean lithogenic flux record for the last 410 ka that covaries with the Antarctic and sub‐Antarctic dust records Westerly wind‐transported material from New Zealand is the most likely dust source over glacial‐interglacial cycles Silt‐sized sediment was well sorted by bottom currents, which were more energetic in interglacials than glacials

Magnetic parameters are used extensively to interpret magnetic mineral assemblage variations in environmental studies. Conventional room temperature measurements of bulk magnetic parameters, like the anhysteretic remanent magnetization (ARM) and the ratio of the susceptibility of ARM to magnetic susceptibility (χ), can reflect, respectively, magnetic mineral concentration and/or particle size variations in sediments, although they are not necessarily well suited for identifying magnetic components within individual magnetic mineral assemblages. More advanced techniques, such as first‐order reversal curve (FORC) diagrams and low‐temperature (LT) magnetic measurements, can enable detailed discrimination of magnetic assemblages. Here, we integrate conventional bulk magnetic measurements alongside FORC diagrams, LT measurements, and X‐ray fluorescence core‐scan data, transmission electron microscope observations, and principal component analysis of FORC diagrams to identify and quantify magnetic mineral assemblages in eastern Mediterranean sediments. The studied sediments were selected because they contain complexly varying mixtures of detrital, biogenic, and diagenetically altered magnetic mineral assemblages that were deposited under varying oxic (organic‐poor marls) to anoxic (organic‐rich sapropels) conditions. Conventional bulk magnetic parameters provide continuous records of environmental magnetic variations, while more time‐consuming LT and FORC measurements on selected samples provide direct ground‐truthing of mineral magnetic assemblages that enables calculation of magnetization contributions of different end members. Thus, a combination of conventional bulk parameters and advanced magnetic techniques can provide detailed records from which the meaning of environmental magnetic signals can be unlocked. We present an assessment of bulk and component‐specific magnetic measurements for sediments deposited under variable redox conditionsBulk magnetic parameters provide valuable delineation of continuous environmental variationsComponent‐specific techniques enable quantification of individual magnetic mineral assemblages to understand environmental variations