Toward a Cenozoic history of atmospheric CO.

The geological record encodes the relationship between climate and atmospheric carbon dioxide (CO) over long and short timescales, as well as potential drivers of evolutionary transitions. However, reconstructing CO beyond direct measurements requires the use of paleoproxies and herein lies the challenge, as proxies differ in their assumptions, degree of understanding, and even reconstructed values. In this study, we critically evaluated, categorized, and integrated available proxies to create a high-fidelity and transparently constructed atmospheric CO record spanning the past 66 million years.

The PhanSST global database of Phanerozoic sea surface temperature proxy data.

Paleotemperature proxy data form the cornerstone of paleoclimate research and are integral to understanding the evolution of the Earth system across the Phanerozoic Eon. Here, we present PhanSST, a database containing over 150,000 data points from five proxy systems that can be used to estimate past sea surface temperature. The geochemical data have a near-global spatial distribution and temporally span most of the Phanerozoic.

Electromyographic Characteristics of a Single Motion Shoulder Exercise: A Pilot Study Investigating a Novel Shoulder Exercise.

Background: Shoulder exercises focused on strengthening the rotator cuff and scapular stabilizing muscles as well as addressing scapular dyskinesis and motor control have been shown to improve rotator cuff function and decrease shoulder pain. A single motion shoulder exercise that effectively activates the rotator cuff and scapular stabilizing muscles, engages the scapulohumeral rhythm, and includes eccentric contractions may be more effective and easier for patients to consistently perform as compared to multiple standard shoulder exercises.

Purpose: To compare the electromyographic muscle activation of key shoulder complex muscles during a single motion exercise and individual exercises (standard exercises) typically included in shoulder rehabilitation protocols.

On impact and volcanism across the Cretaceous-Paleogene boundary.

The cause of the end-Cretaceous mass extinction is vigorously debated, owing to the occurrence of a very large bolide impact and flood basalt volcanism near the boundary. Disentangling their relative importance is complicated by uncertainty regarding kill mechanisms and the relative timing of volcanogenic outgassing, impact, and extinction. We used carbon cycle modeling and paleotemperature records to constrain the timing of volcanogenic outgassing.

Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact.

Mass extinction at the Cretaceous-Paleogene (K-Pg) boundary coincides with the Chicxulub bolide impact and also falls within the broader time frame of Deccan trap emplacement. Critically, though, empirical evidence as to how either of these factors could have driven observed extinction patterns and carbon cycle perturbations is still lacking. Here, using boron isotopes in foraminifera, we document a geologically rapid surface-ocean pH drop following the Chicxulub impact, supporting impact-induced ocean acidification as a mechanism for ecological collapse in the marine realm.

Triple Isotope Fractionation Exponents of Elements Measured by MC-ICP-MS-An Example of Mg.

In most chemical reactions, stable isotopes are fractionated in a mass-dependent manner, yielding correlated isotope ratios in elements with three or more stable isotopes. The proportionality between isotope ratios is set by the triple isotope fractionation exponent θ that can be determined precisely for, ., sulfur and oxygen by IRMS, but not for metal(loid) elements due to the lower precision of MC-ICP-MS analysis and smaller isotopic variations.

Biogeochemical significance of pelagic ecosystem function: an end-Cretaceous case study.

Pelagic ecosystem function is integral to global biogeochemical cycling, and plays a major role in modulating atmospheric CO2 concentrations (pCO2). Uncertainty as to the effects of human activities on marine ecosystem function hinders projection of future atmospheric pCO2 To this end, events in the geological past can provide informative case studies in the response of ecosystem function to environmental and ecological changes. Around the Cretaceous-Palaeogene (K-Pg) boundary, two such events occurred: Deccan large igneous province (LIP) eruptions and massive bolide impact at the Yucatan Peninsula.

Sports medicine training and practice opportunities for emergency physicians.

Background: There is growing interest among emergency physicians to seek additional training in Sports Medicine (SM) and to add it to their clinical practice. This presents unique training and practice management issues. The majority of Primary Care SM fellowship programs list that they will accept emergency physicians, and approximately one-third have already had an emergency physician as an SM fellow.