Astronomical and Tectonic Influences on Climate and Deposition Revealed Through Radioisotopic Geochronology and Bayesian Age-Depth Modeling of the Early Eocene Green River Formation, Wyoming, USA

The Wilkins Peak Member (WPM) of the Green River Formation in Wyoming, USA, comprises alternating lacustrine and alluvial strata that preserve a record of terrestrial climate during the early Eocene climatic optimum. We use a Bayesian framework to develop age-depth models for three sites, based on new 40Ar/39Ar sanidine and 206Pb/238U zircon ages from seven tuffs. The new models provide two- to ten-fold increases in temporal resolution compared to previous radioisotopic age models, confirming eccentricity-scale pacing of WPM facies, and permitting their direct comparison to astronomical solutions. Starting at ca. 51 Ma, the median ages for basin-wide flooding surfaces atop six successive alluvial marker beds coincide with short eccentricity maxima in the astronomical solutions. These eccentricity maxima have been associated with hyperthermal events recorded in marine strata during the early Eocene. WPM strata older than ca. 51 Ma do not exhibit a clear relationship to the eccentricity solutions, but accumulated 31%–35% more rapidly, suggesting that the influence of astronomical forcing on sedimentation was modulated by basin tectonics. Additional high-precision radioisotopic ages are needed to reduce the uncertainty of the Bayesian model, but this approach shows promise for unambiguous evaluation of the phase relationship between alluvial marker beds and theoretical eccentricity solutions

Exploring Radioisotopic Geochronology and Astrochronology

Numerical dating of the geologic record provides an essential framework for interpreting the rich history of our planet. Common applications include the determination of dates for extinction events and climate reorganizations, the assessment of rates of paleoenvironmental and paleobiologic change, and the correlation of rocks across vast expanses. Such investigations have yielded crucial insight into the mechanisms that shape Earth\u27s surface environments over geologic time. But as geologists increasingly pursue high (spatial) resolution stratigraphic analyses in deep time, the short temporal scales (\u3c100,000 years) of the processes investigated push the limits of high-­precision geochronology

Ethofumesate-resistant annual bluegrass (Poa annua) in grass seed production systems

The prolific seed production and polyploidy of annual bluegrass allow for the rapid development of herbicide resistance. Ethofumesate-resistant annual bluegrass plants were identified in the 1990s in grass seed production in Oregon, but their prevalence and distribution are not well documented. Therefore a dose–response experiment was initiated to determine the potential level of ethofumesate resistance in seed production systems. Seeds from 55 annual bluegrass populations were obtained from three sources: seed production fields (31 populations), the seed cleaning process (6 populations), and seed testing lots prior to retail distribution (18 populations). Additionally, two populations, one with known ethofumesate resistance and one with known susceptibility, were identified in preliminary testing and used as controls in this experiment. Seed from each collected population was increased. Individual seedlings were then transplanted into separate cone-tainers, grown to a size of 2 to 3 tillers in the greenhouse, and then sprayed using a compressed air track spray chamber with 10 doses of ethofumesate at 0, 0.56, 1.1, 2.8, 5.6, 8.4, 11.2, 16.8, 22.4, and 44.8 kg ai ha−1, with 0.84 to 2.2 kg ha−1 as the label application rate for perennial ryegrass. The resistant to susceptible ratio of populations across all sources ranged from 0.5 to 5.5. The most resistant populations found in production fields, seed cleaning, and seed testing lots had the effective dose necessary to kill 50% of the population (ED50) of 12.1, 9.4, and 13.1 kg ha−1, respectively. Furthermore, 68% of the populations found in production fields had ED50 higher than 6 kg ha−1, indicating common annual bluegrass resistance in grass seed production. As such, growers should implement integrated weed management strategies, as herbicides alone will likely be ineffective at controlling annual bluegrass

Characterization of Pulmonary Metastases in Children With Hepatoblastoma Treated on Children\u27s Oncology Group Protocol AHEP0731 (The Treatment of Children With All Stages of Hepatoblastoma): A Report From the Children\u27s Oncology Group.

Purpose To determine whether the pattern of lung nodules in children with metastatic hepatoblastoma (HB) correlates with outcome. Methods Thirty-two patients with metastatic HB were enrolled on Children\u27s Oncology Group Protocol AHEP0731 and treated with vincristine and irinotecan (VI). Responders to VI received two additional cycles of VI intermixed with six cycles of cisplatin/fluorouracil/vincristine/doxorubicin (C5VD), and nonresponders received six cycles of C5VD alone. Patients were imaged after every two cycles and at the conclusion of therapy. All computed tomography scans and pathology reports were centrally reviewed, and information was collected regarding lung nodule number, size, laterality, timing of resolution, and pulmonary surgery. Results Among the 29 evaluable patients, only 31% met Response Evaluation Criteria in Solid Tumors (RECIST) for measurable metastatic disease. The presence of measurable disease by RECIST, the sum of nodule diameters greater than or equal to the cumulative cohort median size, bilateral disease, and ≥ 10 nodules were each associated with an increased risk for an event-free survival event ( P = .48, P = .08, P = .065, P = .03, respectively), with nodule number meeting statistical significance. Ten patients underwent pulmonary resection/metastasectomy at various time points, the benefit of which could not be determined because of small patient numbers. Conclusion Children with metastatic HB have a poor prognosis. Overall tumor burden may be an important prognostic factor for these patients. Lesions that fail to meet RECIST size criteria (ie, those \u3c 10 mm) at diagnosis may contain viable tumor, whereas residual lesions at the end of therapy may constitute eradicated tumor/scar tissue. Patients may benefit from risk stratification on the basis of the burden of lung metastatic disease at diagnosis

Effect on mortality and virological response of delaying antiretroviral therapy initiation in children receiving tuberculosis treatment

To estimate the effect of delaying antiretroviral treatment (ART) for 15, 30, or 60 days after tuberculosis (TB) treatment initiation on mortality and virological suppression

Effectiveness of the “Timed Up and Go” (TUG) and the Chair Test as Screening Tools for Geriatric Fall Risk Assessment in the ED

OBJECTIVE: We sought to evaluate the effectiveness of the Timed Up and Go (TUG) and the Chair test as screening tools in the Emergency Department (ED), stratified by sex. METHODS: This prospective cohort study was conducted at a Level 1 Trauma center. After consent, subjects performed the TUG and the Chair test. Subjects were contacted for phone follow-up and asked to self-report interim falling. RESULTS: Data from 192 subjects were analyzed. At baseline, 71.4% (n = 137) screened positive for increased falls risk based on the TUG evaluation, and 77.1% (n = 148) scored below average on the Chair test. There were no differences by patient sex. By the six-month evaluation 51 (26.6%) study participants reported at least one fall. Females reported a non-significant higher prevalence of falls compared to males (29.7% versus 22.2%, p = 0.24). TUG test had a sensitivity of 70.6% (95% CI: 56.2%-82.5%), a specificity of 28.4% (95% CI: 21.1%-36.6%), a positive predictive (PP) value 26.3% (95% CI: 19.1%-34.5%) and a negative predictive (NP) value of 72.7% (95% CI: 59.0%-83.9%). Similar results were observed with the Chair test. It had a sensitivity of 78.4% (95% CI: 64.7%-88.7%), a specificity of 23.4% (95% CI: 16.7%-31.3%), a PP value 27.0% (95% CI: 20.1%-34.9%) and a NP value of 75.0% (95% CI: 59.7%-86.8%). No significant differences were observed between sexes. CONCLUSIONS: There were no sex specific significant differences in TUG or Chair test screening performance. Neither test performed well as a screening tool for future falls in the elderly in the ED setting