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An introduction to the life of John Wilkes Booth, the man who assasinated the sixteenth president, Abraham Lincoln.

On multimillion-year time scales, Earth has experienced warm ice-free and cold glacial climates, but it is unknown whether transitions between these background climate states were the result of changes in carbon dioxide sources or sinks. Low-latitude arc-continent collisions are hypothesized to drive cooling by exhuming and eroding mafic and ultramafic rocks in the warm, wet tropics, thereby increasing Earth’s potential to sequester carbon through chemical weathering. To better constrain global weatherability through time, the paleogeographic position of all major Phanerozoic arc-continent collisions was reconstructed and compared to the latitudinal distribution of ice sheets. This analysis reveals a strong correlation between the extent of glaciation and arc-continent collisions in the tropics. Earth’s climate state is set primarily by global weatherability, which changes with the latitudinal distribution of arc-continent collisions.

Diane L. Swanson demonstrates that a new frontier for corporate social responsibility is possible in theory and practice. The key idea - discovery leadership - enables corporate managers to deal effectively with problems, issues, and value clashes occurring where the corporation and society come together.

Our understanding of Earth's paleogeography relies heavily on paleomagnetic apparent polar wander paths (APWPs), which represent the time‐dependent position of Earth's spin axis relative to a given block of lithosphere. However, conventional approaches to APWP construction have significant limitations. First, the paleomagnetic record contains substantial noise that is not integrated into APWPs. Second, parametric assumptions are adopted to represent spatial and temporal uncertainties even where the underlying data do not conform to the assumed distributions. The consequences of these limitations remain largely unknown. Here, we address these challenges with a bottom‐up Monte Carlo uncertainty propagation scheme that operates on site‐level paleomagnetic data. To demonstrate our methodology, we present an extensive compilation of site‐level Cenozoic paleomagnetic data from North America, which we use to generate a high‐resolution APWP. Our results demonstrate that even in the presence of substantial noise, polar wandering can be assessed with unprecedented temporal and spatial resolution. Plain Language Summary Records of Earth's ancient magnetic field preserved in rocks provide valuable information for understanding past tectonic plate motions. These “paleomagnetic” records are collected from individual rock samples and subsequently grouped to develop global‐scale paths called apparent polar wander (APW) paths. However, the standard methods for analyzing and grouping paleomagnetic data are limited in the way they propagate and quantify uncertainties, and the consequences of these limitations are not known. In this study, we address these limitations through the introduction of a new methodological approach, which we use to study a large data set of paleomagnetic data from North America for the past 60 million years. We demonstrate that through our new methodology it is possible to generate APW paths with unprecedented spatial and temporal resolution, which may offer new insights into Earth's deep time evolution. Key Points We present an extensive compilation of Cenozoic paleomagnetic and geochronologic data from North America at the site level A bottom‐up Monte Carlo uncertainty propagation scheme enables the propagation of errors from site level data into apparent polar wander paths These advances allowed us to describe Cenozoic North American polar wander at the unprecedented temporal resolution of 1 Myr

Steep topography, a tropical climate, and mafic lithologies contribute to efficient chemical weathering and carbon sequestration in the Southeast Asian islands. Ongoing arc–continent collision between the Sunda-Banda arc system and Australia has increased the area of subaerially exposed land in the region since the mid-Miocene. Concurrently, Earth’s climate has cooled since the Miocene Climatic Optimum, leading to growth of the Antarctic ice sheet and the onset of Northern Hemisphere glaciation. We seek to evaluate the hypothesis that the emergence of the Southeast Asian islands played a significant role in driving this cooling trend through increasing global weatherability. To do so, we have compiled paleoshoreline data and incorporated them into GEOCLIM, which couples a global climate model to a silicate weathering model with spatially resolved lithology. We find that without the increase in area of the Southeast Asian islands over the Neogene, atmospheric pCO₂ would have been significantly higher than preindustrial values, remaining above the levels necessary for initiating Northern Hemisphere ice sheets.

Inclination is the angle of a magnetization vector from horizontal. Clastic sedimentary rocks often experience inclination shallowing whereby syn‐ to post‐depositional processes result in flattened detrital remanent magnetizations relative to local geomagnetic field inclinations. The deviation of recorded inclinations from true values presents challenges for reconstructing paleolatitudes. A widespread approach for estimating flattening factors (f) compares the shape of an assemblage of magnetization vectors to that derived from a paleosecular variation model (the elongation/inclination [E/I] method). Few studies exist that compare the results of this statistical approach with empirically determined flattening factors and none in the Proterozoic Eon. In this study, we evaluate inclination shallowing within 1.1 billion‐year‐old, hematite‐bearing red beds of the Cut Face Creek Sandstone that is bounded by lava flows of known inclination. Taking this inclination from the volcanics as the expected direction, we found that detrital hematite remanence is flattened with f=0.650.560.75$f=0.6{5}_{0.56}^{0.75}$whereas the pigmentary hematite magnetization shares a common mean with the volcanics. Using the pigmentary hematite direction as the expected inclination results in f=0.610.550.67$f=0.6{1}_{0.55}^{0.67}$ . These flattening factors are consistent with those estimated through the E/I method f=0.640.510.85$\\left(f=0.6{4}_{0.51}^{0.85}\\right)$supporting its application in deep time. However, all methods have significant uncertainty associated with determining the flattening factor. This uncertainty can be incorporated into paleomagnetic poles with the resulting ellipse approximated with a Kent distribution. Rather than seeking to find “the flattening factor,” or assuming a single value, the inherent uncertainty in flattening factors should be recognized and incorporated into paleomagnetic syntheses. Plain Language Summary The magnetization of ancient sedimentary rocks provides great insight into Earth's past. Earth scientists use these rocks to understand how Earth's magnetic field has flipped through time and to reconstruct how continents have moved. Hematite is a common mineral which gives many sandstones a red color—leading geologists to refer to them as “red beds.” While hematite is a reliable magnet through time, the magnetic directions recorded by hematite grains can be shallower than the geomagnetic field (i.e., they are flattened). Magnetization steepness is how Earth scientists determine the latitude where rocks were deposited as the magnetic field gets steeper toward the pole. We need ways to correct for magnetization shallowing in sedimentary rocks. In this study, we compared the steepness of magnetic directions held by hematite to that of lava flows that formed in the same time interval. Magnetic directions from lava flows are not flattened so this comparison allows us to determine the shallowing amount. We compare it to a statistical method and see that the results are indistinguishable within the appreciable uncertainty of the methods. Earth scientists should include the uncertainty associated with inclination shallowing when they report ancient pole positions determined from such flattened magnetic directions. Key Points Inclination shallowing is empirically quantified in 1.1 Ga clastic sedimentary rocks bracketed by volcanics Detrital hematite remanence is flattened by a factor of 0.610.550.67$0.6{1}_{0.55}^{0.67}$relative to unflattened pigmentary hematite Flattening factor uncertainty is present in all methods and should be incorporated into the uncertainty of sedimentary paleomagnetic poles

Phenotypic flexibility allows individuals to reversibly modify trait values and theory predicts an individual’s relative degree of flexibility positively correlates with the environmental heterogeneity it experiences. We test this prediction by integrating surveys of population genetic and physiological variation with thermal acclimation experiments and indices of environmental heterogeneity in the Dark-eyed Junco ( Junco hyemalis ) and its congeners. We combine field measures of thermogenic capacity for 335 individuals, 22,006 single nucleotide polymorphisms genotyped in 181 individuals, and laboratory acclimations replicated on five populations. We show that Junco populations: (1) differ in their thermogenic responses to temperature variation in the field; (2) harbor allelic variation that also correlates with temperature heterogeneity; and (3) exhibit intra-specific variation in thermogenic flexibility in the laboratory that correlates with the heterogeneity of their native thermal environment. These results provide comprehensive support that phenotypic flexibility corresponds with environmental heterogeneity and highlight its importance for coping with environmental change. Theory predicts that organisms in varied environments should evolve to be more phenotypically flexible. Evidence combining genetic and physiological variation with thermal acclimation experiments shows that the thermogenic flexibility of wild juncos is greatest in populations where temperatures are most variable.

Since its inception, osteopathic medicine has sought to identify the mechanical causes of disease and to understand the body's structure-function relationship. Research conducted during the past 25 years has demonstrated that the architectural principles of tensegrity can be applied to biological organisms (termed ) and that these principles can demonstrate the mechanical structure-function relationship at all size scales in the human body. Further, biotensegrity at the cellular level allows the cell to mechanically sense its environment and convert mechanical signals into biochemical changes. When applied to the principles of osteopathic medicine, biotensegrity provides a conceptual understanding of the hierarchical organization of the human body and explains the body's ability to adapt to change. Further, biotensegrity explains how mechanical forces applied during osteopathic manipulative treatment could lead to effects at the cellular level, providing a platform for future research on the mechanisms of action of osteopathic manipulative treatment.

Though hippocampal volume reduction is a pathological hallmark of schizophrenia, the molecular pathway(s) responsible for this degeneration remains unknown. Recent reports have suggested the potential role of impaired blood-brain barrier (BBB) function in schizophrenia pathogenesis. However, direct evidence demonstrating an impaired BBB function is missing. In this preliminary study, we used immunohistochemistry and serum immunoglobulin G (IgG) antibodies to investigate the state of BBB function in formalin-fixed postmortem samples from the hippocampus and surrounding temporal cortex of schizophrenia patients with schizophrenia (n=25) and non-schizophrenia controls without schizophrenia (n=27) matched for age, sex, and race. Since a functional BBB prevents the extravasation of IgGs, detection of IgGs in the parenchyma is used as direct evidence of BBB breakdown. We also developed a semi-quantitative approach to quantify the extent of IgG leak and therein BBB breach. Analysis of our immunohistochemistry data demonstrated a significantly higher incidence of IgG leak in schizophrenia patients with schizophrenia compared to controls. Further, BBB permeability was significantly higher in advanced-age patients with schizophrenia patients than both advanced-age controls and middle-aged schizophrenia patients with schizophrenia. Male patients with schizophrenia patients also demonstrated increased IgG permeability compared to control males. Interestingly, the extravasated IgGs also demonstrated selective immunoreactivity for neurons. Based on these observations, we suggest that BBB dysfunction and IgG autoantibodies could be two key missing pathoetiological links underwriting schizophrenia hippocampal damage.

To present a multiyear clinical experience with intravenous bevacizumab for the management of severe gastrointestinal bleeding and/or epistaxis in patients with hereditary hemorrhagic telangiectasia (HHT). All patients treated with intravenous bevacizumab for severe hereditary hemorrhagic telangiectasia–related bleeding from June 1, 2013, through January 31, 2017, were included in this report. Severity of epistaxis (determined using the Epistaxis Severity Score questionnaire); hemoglobin, iron, and ferritin levels; and quality of life data were collected serially in all patients. Intravenous bevacizumab was administered to 34 patients using a standardized treatment protocol. Anemia was primarily related to severe epistaxis (n=15, 44%), severe gastrointestinal bleeding (n=4, 12%), or both (n=15, 44%), with a median baseline hemoglobin level of 9.1 g/dL (range, 8.3-10.5 gm/dL; to convert to mmol/L, multiply by 0.62). Red blood cell (RBC) transfusions had been administered to 28 patients (82%). Of these, 16 patients (47%) were RBC transfusion dependent and had received a median of 75 RBC transfusions (range, 4->500 RBC units) before bevacizumab initiation. The median length of follow-up was 17.6 months from the beginning of bevacizumab treatment (range, 3-42.5 months). There was a significant reduction in epistaxis severity scores (P<.001) and RBC transfusion requirements (P=.007) after completion of the initial bevacizumab treatment cycle. New-onset or worsened hypertension was noted in 4 patients, with 1 patient experiencing hypertensive urgency with a temporary decline in renal function. Intravenous bevacizumab is an effective treatment option for patients with severe anemia related to epistaxis and/or gastrointestinal bleeding. Further studies are needed to establish a dose-response relationship as well as clinical, genetic, and biomarker predictors of response.