27 results on '"Meyers SR"'
Search Results
2. LETTERS@USNEWS.COM.
- Author
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MINGO, MICHAEL, BAKER, BOB, PARKER, BRIAN, Karasek, Tom, Graham, Leonard E., and MEYERS, SR., JOEL
- Published
- 2011
3. Simple steps to grow your chapter.
- Author
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Meyers Sr., Byron
- Abstract
The article offers suggestions that chapter members of Barbershop Harmony Society can personally do to make their chapter more attractive to potential members. It suggests that members should tell others what their chapter can offer them. A positive attitude towards improving the chapter that would create interest from prospective members should be maintained. Member should establish a personal goal of recruiting a new members.
- Published
- 2007
4. A 650-Myr history of Earth's axial precession frequency and the evolution of the Earth-Moon system derived from cyclostratigraphy.
- Author
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Wu Y, Malinverno A, Meyers SR, and Hinnov LA
- Abstract
The preservation of Milankovitch cycles in the stratigraphic record provides independent geological information to study our ancient solar system and can be leveraged to constrain existing theoretical models. Here, we identify 34 high-quality cyclostratigraphic records spanning the past 650 million years and use them to infer the evolution of the Earth-Moon system through a Bayesian inversion method. We reconstruct the time evolution of Earth's axial precession frequency, lunar distance, length of day, and the periods of obliquity and climatic precession cycles. The results indicate an interval of high tidal energy dissipation in the Earth-Moon system at ~300 to 200 million years ago, and are broadly consistent with an independently calculated tidal evolution model. Our results provide an improved determination of the past periods of obliquity and climatic precession for astrochronology applications and yield important constraints on the history of tidal energy dissipation during the Phanerozoic Eon.
- Published
- 2024
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5. Millennial-scale variability of the Antarctic ice sheet during the early Miocene.
- Author
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Sullivan NB, Meyers SR, Levy RH, McKay RM, Golledge NR, and Cortese G
- Abstract
Millennial-scale ice sheet variability (1-15 kyr periods) is well documented in the Quaternary, providing insight into critical atmosphere-ocean-cryosphere interactions that can inform the mechanism and pace of future climate change. Ice sheet variability at similar frequencies is comparatively less known and understood prior to the Quaternary during times, where higher atmospheric p CO
2 and warmer climates prevailed, and continental-scale ice sheets were largely restricted to Antarctica. In this study, we evaluate a high-resolution clast abundance dataset (ice-rafted debris) that captures East Antarctic ice sheet variability in the western Ross Sea during the early Miocene. This dataset is derived from a 100 m-thick mudstone interval in the ANtarctic DRILLing (ANDRILL or AND) core 2A, which preserves a record of precession and eccentricity variability. The sedimentation rates are of appropriate resolution to also characterize the signature of robust, subprecession cyclicity. Strong sub-precession (~10 kyr) cyclicity is observed, with an amplitude modulation in lockstep with eccentricity, indicating a relationship between high-frequency Antarctic ice sheet dynamics and astronomical forcing. Bicoherence analysis indicates that many of the observed millennial-scale cycles (as short as 1.2 kyr) are associated with nonlinear interactions (combination or difference tones) between each other and the Milankovitch cycles. The presence of these cycles during the Miocene reveals the ubiquity of millennial-scale ice sheet variability and sheds light on the interactions between Earth's atmosphere, ocean, and ice in climates warmer than the Quaternary.- Published
- 2023
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6. Outcomes of Acute Pancreatitis in Hospitalized Patients With Generalized Anxiety Disorder.
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Saiganesh P, Kaye AJ, Patel SJ, Meyers SR, Mathew AG, and Wang W
- Abstract
Introduction Acute pancreatitis (AP) is a common cause of hospitalization in the United States. There is evidence that chronic stress increases the risk for more severe AP episodes. One common form of chronic stress is generalized anxiety disorder (GAD). The purpose of this research was to investigate the impact of GAD on the outcomes of adult patients admitted to the hospital with AP. Methods Utilizing the 2014 National Inpatient Sample database and International Classification of Diseases, Ninth Edition Revision (ICD) codes, AP patients were selected. Common inpatient outcomes of AP patients with and without GAD were examined. The outcomes studied were acute renal failure, acute respiratory failure, sepsis, acute deep vein thrombosis, myocardial infarction, intestinal perforation, and inpatient mortality. A multivariate logistic regression analysis was conducted to assess if GAD was an independent predictor for these outcomes. Results Among 82,156 adult patients hospitalized for AP during the 2014 year, 10,611 of them had coexisting GAD. AP patients with comorbid GAD were found to have an increased likelihood of acute renal failure (aOR = 1.19, 95% confidence interval (CI) = 1.11-1.28, p < 0.001), sepsis (aOR = 1.09, 95% CI = 1.01 -1.19, p = 0.037), acute deep vein thrombosis (aOR = 1.63, 95% CI = 1.06-2.50, p = 0.025), and inpatient mortality (aOR = 1.62, 95% C = I 1.27-2.08, p < 0.001). There was no statistically significant difference found between the two cohorts for the outcomes of myocardial infarction and intestinal perforation. Conclusion In patients hospitalized with AP, those with coexisting GAD were found to have an increased risk of developing acute renal failure, sepsis, acute deep vein thrombosis, and inpatient mortality. There may be benefits to identifying AP patients with comorbid GAD at the time of admission and monitoring them more carefully during their hospitalization to help identify early signs of complications or prevent the negative outcomes seen in this study., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Saiganesh et al.)
- Published
- 2023
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7. Climate system asymmetries drive eccentricity pacing of hydroclimate during the early Eocene greenhouse.
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Walters AP, Tierney JE, Zhu J, Meyers SR, Graves K, and Carroll AR
- Abstract
The early Eocene Climatic Optimum (EECO) represents the peak of Earth's last sustained greenhouse climate interval. To investigate hydroclimate variability in western North America during the EECO, we developed an orbitally resolved leaf wax δ
2 H record from one of the most well-dated terrestrial paleoclimate archives, the Green River Formation. Our δ2 Hwax results show ∼60‰ variation and evidence for eccentricity and precession forcing. iCESM simulations indicate that changes in the Earth's orbit drive large seasonal variations in precipitation and δ2 H of precipitation at our study site, primarily during the summer season. Our findings suggest that the astronomical response in δ2 Hwax is attributable to an asymmetrical climate response to the seasonal cycle, a "clipping" of precession forcing, and asymmetric carbon cycle dynamics, which further enhance the influence of eccentricity modulation on the hydrological cycle during the EECO. More broadly, our study provides an explanation for how and why eccentricity emerges as a dominant frequency in climate records from ice-free greenhouse worlds.- Published
- 2023
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8. Outcomes of Gastroparesis in Hospitalized Patients With Generalized Anxiety Disorder.
- Author
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Mathew AG, Kaye AJ, Patel SJ, Meyers SR, Saiganesh P, and Wang W
- Abstract
Background Gastroparesis is a common gastrointestinal pathology that has been increasing in prevalence and represents a significant cost to the United States healthcare system. Gastroparesis is associated with psychological dysfunction, including generalized anxiety disorder (GAD). GAD is known to be a prevalent and chronic manifestation of anxiety, which has been increasing in prevalence since the year 2020. Despite the association between gastroparesis and GAD, there has been limited research on the possible impact GAD may have on the morbidity and mortality of patients hospitalized for gastroparesis, which is further evaluated in this study. Methods Using the Nationwide Inpatient Sample from the year 2014, a retrospective study was conducted to assess the outcomes of hospitalized gastroparesis patients with and without a history of GAD. In this study, the analyzed outcomes included acute kidney injury (AKI), acute respiratory failure, sepsis, acute deep vein thrombosis, myocardial infarction, intestinal obstruction, and inpatient mortality. To assess whether GAD is an independent risk factor for the outcomes, a multivariate logistic regression analysis was used. Results There were 22,150 patients with gastroparesis assessed in this study; GAD was found to be a comorbid diagnosis in 4,196 of those patients. In the GAD cohort, there was an elevated risk for AKI (adjusted odds ratio 1.24, p < 0.001). The adjusted odds ratios for acute respiratory failure, sepsis, acute deep vein thrombosis, myocardial infarction, intestinal obstruction, and inpatient mortality did not meet the threshold for statistical significance. Conclusion In hospitalized gastroparesis patients, GAD is a risk factor for AKI. This finding may be attributed to prerenal azotemia due to an increased risk of nausea and vomiting associated with GAD, as well as the medications used to treat GAD such as escitalopram and duloxetine. In addition, the dual inflammatory states caused by the co-existence of both GAD and gastroparesis may also have a role in increasing the risk for AKI. The results of this study may become increasingly relevant given the increasing prevalence of GAD. ., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Mathew et al.)
- Published
- 2023
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9. Outcomes of Patients Hospitalized for Acute Diverticulitis With Comorbid Generalized Anxiety Disorder.
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Kaye AJ, Patel SJ, Meyers SR, Saiganesh P, and Ahlawat S
- Abstract
Introduction Diverticular disease and anxiety disorders are common in the general population. Prior research on diverticular disease showed that these patients have an increased frequency of anxiety and depression. The objective of this study was to explore the impact of generalized anxiety disorder (GAD) on the outcomes of adult patients admitted with acute diverticulitis. Methods Using the National Inpatient Sample database from the year 2014 and International Classification of Diseases, Ninth Edition Revision, Clinical Modification (ICD-9 CM) codes, acute diverticulitis patients were selected. The outcomes of diverticulitis patients with and without GAD were explored. The outcomes of interest included inpatient mortality, hypotension/shock, acute respiratory failure, acute hepatic failure, sepsis, intestinal abscess, intestinal obstruction, myocardial infarction, acute renal failure, and colectomy. A multivariate logistic regression analysis was performed to determine if GAD is an independent predictor for the outcomes. Results Among 77,520 diverticulitis patients in the study, 8,484 had comorbid GAD. GAD was identified as a risk factor for intestinal obstruction (adjusted odds ratio (aOR) 1.22, 95% CI: 1.05-1.43, p<0.05), and intestinal abscess (aOR 1.19, 95% CI: 1.10-1.29, p<0.05). GAD was found to be a protective factor for hypotension/shock (aOR 0.83, 95% CI: 0.76-0.91, p<0.05) and acute respiratory failure (aOR 0.76, 95% CI: 0.62-0.93, p<0.05). The aORs of sepsis, inpatient mortality, myocardial infarction, acute renal failure, and colectomy were not statistically significant. Conclusions Patients with acute diverticulitis who are also diagnosed with GAD are at increased risk for intestinal obstruction and intestinal abscess, which may be due to the influence GAD has on the gut microbiota as well as the impact of GAD pharmacotherapy on gut motility. There was also a decreased risk for acute respiratory failure and hypotension/shock appreciated in the GAD cohort which may be attributable to the elevated healthcare resource utilization seen generally in GAD patients, which may allow for presentation to the emergency department, hospitalization, and treatment earlier in the diverticulitis disease course., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Kaye et al.)
- Published
- 2023
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10. Exploring the depths of Solar System evolution.
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Meyers SR and Peters SE
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- Solar System
- Published
- 2022
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11. Outcomes of Patients Who Developed Clostridioides difficile Infection During Hospitalization and Had a History of Comorbid Post-Traumatic Stress Disorder.
- Author
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Patel SJ, Kaye A, Meyers SR, and Ahlawat S
- Abstract
Introduction: Clostridioides difficile ( C. difficile ), is a common cause of nosocomial diarrhea. Antibiotic use is a risk factor for developing C. difficile infection (CDI). Clinical presentations of CDI range from mild diarrhea to fulminant colitis. A history of anxiety increases the risk of developing irritable bowel syndrome following CDI. Post-traumatic stress disorder (PTSD) is a common form of anxiety and is associated with several medical comorbidities. This study explores the impact PTSD has on the outcomes of adult patients who develop CDI while hospitalized., Methods: Hospitalized adults who had developed CDI were selected from the 2014 National Inpatient Sample database using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9) codes. The outcomes of CDI patients with and without comorbid PTSD were explored. The outcomes assessed in this study were inpatient mortality, sepsis, hypotension/shock, acute renal failure, acute respiratory failure, megacolon, colonic perforation, and intestinal abscess. Independent t-tests and chi-squared tests were used to compare means and proportions, respectively. A multivariate logistic regression analysis was utilized to determine whether PTSD is an independent predictor of the outcomes., Results: Among 72,383 hospitalized adults who developed CDI in the year 2014, 465 also had a diagnosis of PTSD. PTSD was found to be an independent risk factor for inpatient mortality (adjusted odds ratio {aOR} 2.93, 95% confidence interval (CI): 1.39-6.21, p = 0.005), and sepsis (aOR 1.61, 95% CI: 1.24-2.07, p = 0.001). However, PTSD was not a risk factor for hypotension/shock (aOR 1.26, 95% CI: 0.97-1.63, p = 0.080), acute renal failure (aOR 1.02, 95% CI: 0.81-1.28, p = 0.895), or acute respiratory failure (aOR 1.15, 95% CI: 0.83-1.58, p = 0.412) in patients with CDI. Due to small sample sizes of patients who developed megacolon, colonic perforation, and intestinal abscess, further analysis of these outcomes was not performed., Conclusion: Inpatients who develop CDI with comorbid PTSD are at increased risk for sepsis and inpatient mortality. These findings may be due to the impact of PTSD's dysregulation of the hypothalamic-pituitary axis leading to low cortisol production, increased serum cytokine concentrations, and/or increased intestinal inflammation. Awareness of these increased risks when triaging CDI patients with PTSD and possibly increased psychiatric interventions to treat PTSD may be necessary to help reduce the risk of sepsis and inpatient mortality in this subgroup of patients., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Patel et al.)
- Published
- 2022
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12. Outcomes of Inflammatory Bowel Disease in Hospitalized Patients With Generalized Anxiety Disorder.
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Kaye AJ, Patel SJ, Meyers SR, and Ahlawat S
- Abstract
Background The development of inflammatory bowel disease (IBD), which encompasses ulcerative colitis and Crohn's disease, is multifactorial. Stress from anxiety is a risk factor for IBD. Generalized anxiety disorder (GAD) is twice as likely in IBD patients. This study explores the outcomes of patients hospitalized for IBD with comorbid GAD. Methods A retrospective analysis utilizing the 2014 USA National Inpatient Sample database was performed to assess the outcomes of hospitalized IBD patients with and without GAD. The outcomes analyzed were sepsis, acute hepatic failure, hypotension/shock, acute respiratory failure, acute deep vein thrombosis, acute renal failure, intestinal obstruction, myocardial infarction, ileus, inpatient mortality, colectomy, intestinal abscess, intestinal perforation, and megacolon. A multivariate logistic regression analysis was employed to explore whether GAD is a risk factor for these outcomes. Results Among 28,173 IBD hospitalized patients in the study, GAD was a comorbid diagnosis in 3,400 of those patients. IBD patients with coexisting GAD were found to be at increased risk for acute hepatic failure (adjusted odds ratio (aOR) 1.80, p = 0.006), sepsis (aOR 1.33, p < 0.001), acute respiratory failure (aOR 1.24, p = 0.018), inpatient mortality (aOR 1.87, p < 0.001), intestinal abscess (aOR 2.35, p = 0.013), and intestinal perforation (aOR 1.44, p = 0.019). The aORs for the remaining outcomes were not statistically significant. Conclusions In hospitalized IBD patients, GAD is a risk factor for sepsis, acute hepatic failure, acute respiratory failure, intestinal abscess, intestinal perforation, and inpatient mortality. IBD and GAD are becoming increasingly common, which will likely lead to a larger number of complications among inpatients with these comorbidities., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Kaye et al.)
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- 2022
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13. A large West Antarctic Ice Sheet explains early Neogene sea-level amplitude.
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Marschalek JW, Zurli L, Talarico F, van de Flierdt T, Vermeesch P, Carter A, Beny F, Bout-Roumazeilles V, Sangiorgi F, Hemming SR, Pérez LF, Colleoni F, Prebble JG, van Peer TE, Perotti M, Shevenell AE, Browne I, Kulhanek DK, Levy R, Harwood D, Sullivan NB, Meyers SR, Griffith EM, Hillenbrand CD, Gasson E, Siegert MJ, Keisling B, Licht KJ, Kuhn G, Dodd JP, Boshuis C, De Santis L, and McKay RM
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- Antarctic Regions, Climate Models, History, Ancient, Ice Cover, Sea Level Rise history, Seawater analysis
- Abstract
Early to Middle Miocene sea-level oscillations of approximately 40-60 m estimated from far-field records
1-3 are interpreted to reflect the loss of virtually all East Antarctic ice during peak warmth2 . This contrasts with ice-sheet model experiments suggesting most terrestrial ice in East Antarctica was retained even during the warmest intervals of the Middle Miocene4,5 . Data and model outputs can be reconciled if a large West Antarctic Ice Sheet (WAIS) existed and expanded across most of the outer continental shelf during the Early Miocene, accounting for maximum ice-sheet volumes. Here we provide the earliest geological evidence proving large WAIS expansions occurred during the Early Miocene (~17.72-17.40 Ma). Geochemical and petrographic data show glacimarine sediments recovered at International Ocean Discovery Program (IODP) Site U1521 in the central Ross Sea derive from West Antarctica, requiring the presence of a WAIS covering most of the Ross Sea continental shelf. Seismic, lithological and palynological data reveal the intermittent proximity of grounded ice to Site U1521. The erosion rate calculated from this sediment package greatly exceeds the long-term mean, implying rapid erosion of West Antarctica. This interval therefore captures a key step in the genesis of a marine-based WAIS and a tipping point in Antarctic ice-sheet evolution., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)- Published
- 2021
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14. Development of transfusion guidelines for injured children using a Modified Delphi Consensus Process.
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Trappey AF 3rd, Thompson KM, Kuppermann N, Stephenson JT, Nuno MA, Hewes HA, Meyers SR, Stanley RM, Galante JM, and Nishijima DK
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- Antifibrinolytic Agents therapeutic use, Child, Consensus, Delphi Technique, Humans, Pediatrics methods, Pediatrics standards, Practice Guidelines as Topic, Randomized Controlled Trials as Topic, Blood Transfusion methods, Hemorrhage etiology, Hemorrhage therapy, Tranexamic Acid therapeutic use, Wounds and Injuries complications
- Abstract
Background: There is wide variability of transfusion practices for children with hemorrhagic injuries across trauma centers. We are planning a multicenter, randomized clinical trial evaluating tranexamic acid in children with hemorrhage. Standardization of transfusion practices across sites is important to minimize confounding. Therefore, we sought to generate consensus-based transfusion guidelines for the trial., Methods: We used a modified Delphi process utilizing a multi-site, multi-disciplinary panel of experts to develop our transfusion guidelines. A survey of 23 clinical categories on various aspects of transfusion practices was developed and distributed via SurveyMonkey®. Statements were graded on a 5-point Likert scale ("Strongly agree" to "This intervention may be harmful"). Statements were accepted if ≥ 80% of the panelists rated the statement as "Strongly agree" or "Agree". After each round, the responses were calculated and the results included on subsequent rounds., Results: 35 panelists from four pediatric trauma centers participated in the study, including 11 (31%) pediatric EM physicians, 8 (23%) pediatric trauma surgeons, 5 (14%) transfusionists, 5 (14%) pediatric anesthesiologists, and 6 (17%) pediatric critical care physicians (range of 8 to 10 from each clinical site). Four survey iterations were performed. In total 176 statements were rated and 39 were accepted by criteria across all 23 categories. An rational algorithm for transfusion in trauma was then developed., Conclusions: We successfully developed transfusion guidelines for various aspects of the management of children with hemorrhagic injuries using a modified Delphi process with broad interdisciplinary participation. We anticipate implementation of these guidelines will help minimize heterogeneity of transfusion practices across clinical sites for the upcoming clinical trial evaluating tranexamic acid in children with hemorrhage.
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- 2019
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15. Proterozoic Milankovitch cycles and the history of the solar system.
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Meyers SR and Malinverno A
- Abstract
The geologic record of Milankovitch climate cycles provides a rich conceptual and temporal framework for evaluating Earth system evolution, bestowing a sharp lens through which to view our planet's history. However, the utility of these cycles for constraining the early Earth system is hindered by seemingly insurmountable uncertainties in our knowledge of solar system behavior (including Earth-Moon history), and poor temporal control for validation of cycle periods (e.g., from radioisotopic dates). Here we address these problems using a Bayesian inversion approach to quantitatively link astronomical theory with geologic observation, allowing a reconstruction of Proterozoic astronomical cycles, fundamental frequencies of the solar system, the precession constant, and the underlying geologic timescale, directly from stratigraphic data. Application of the approach to 1.4-billion-year-old rhythmites indicates a precession constant of 85.79 ± 2.72 arcsec/year (2σ), an Earth-Moon distance of 340,900 ± 2,600 km (2σ), and length of day of 18.68 ± 0.25 hours (2σ), with dominant climatic precession cycles of ∼14 ky and eccentricity cycles of ∼131 ky. The results confirm reduced tidal dissipation in the Proterozoic. A complementary analysis of Eocene rhythmites (∼55 Ma) illustrates how the approach offers a means to map out ancient solar system behavior and Earth-Moon history using the geologic archive. The method also provides robust quantitative uncertainties on the eccentricity and climatic precession periods, and derived astronomical timescales. As a consequence, the temporal resolution of ancient Earth system processes is enhanced, and our knowledge of early solar system dynamics is greatly improved., Competing Interests: The authors declare no conflict of interest.
- Published
- 2018
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16. Pacing of Paleozoic macroevolutionary rates by Milankovitch grand cycles.
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Crampton JS, Meyers SR, Cooper RA, Sadler PM, Foote M, and Harte D
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- Animals, Biodiversity, Fossils, Biological Evolution, Climate, Earth, Planet, Extinction, Biological
- Abstract
Periodic fluctuations in past biodiversity, speciation, and extinction have been proposed, with extremely long periods ranging from 26 to 62 million years, although forcing mechanisms remain speculative. In contrast, well-understood periodic Milankovitch climate forcing represents a viable driver for macroevolutionary fluctuations, although little evidence for such fluctuation exists except during the Late Cenozoic. The reality, magnitude, and drivers of periodic fluctuations in macroevolutionary rates are of interest given long-standing debate surrounding the relative roles of intrinsic biotic interactions vs. extrinsic environmental factors as drivers of biodiversity change. Here, we show that, over a time span of 60 million years, between 9 and 16% of the variance in biological turnover (i.e., speciation probability plus species extinction probability) in a major Early Paleozoic zooplankton group, the graptoloids, can be explained by long-period astronomical cycles (Milankovitch "grand cycles") associated with Earth's orbital eccentricity (2.6 million years) and obliquity (1.3 million years). These grand cycles modulate climate variability, alternating times of relative stability in the environment with times of maximum volatility. We infer that these cycles influenced graptolite speciation and extinction through climate-driven changes to oceanic circulation and structure. Our results confirm the existence of Milankovitch grand cycles in the Early Paleozoic Era and show that known processes related to the mechanics of the Solar System were shaping marine macroevolutionary rates comparatively early in the history of complex life. We present an application of hidden Markov models to macroevolutionary time series and protocols for the evaluation of statistical significance in spectral analysis., Competing Interests: The authors declare no conflict of interest.
- Published
- 2018
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17. Theory of chaotic orbital variations confirmed by Cretaceous geological evidence.
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Ma C, Meyers SR, and Sageman BB
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- Climate, History, Ancient, Models, Theoretical, Time Factors, Uncertainty, Earth, Planet, Geology
- Abstract
Variations in the Earth's orbit and spin vector are a primary control on insolation and climate; their recognition in the geological record has revolutionized our understanding of palaeoclimate dynamics, and has catalysed improvements in the accuracy and precision of the geological timescale. Yet the secular evolution of the planetary orbits beyond 50 million years ago remains highly uncertain, and the chaotic dynamical nature of the Solar System predicted by theoretical models has yet to be rigorously confirmed by well constrained (radioisotopically calibrated and anchored) geological data. Here we present geological evidence for a chaotic resonance transition associated with interactions between the orbits of Mars and the Earth, using an integrated radioisotopic and astronomical timescale from the Cretaceous Western Interior Basin of what is now North America. This analysis confirms the predicted chaotic dynamical behaviour of the Solar System, and provides a constraint for refining numerical solutions for insolation, which will enable a more precise and accurate geological timescale to be produced.
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- 2017
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18. Eccentricity and obliquity paced carbon cycling in the Early Triassic and implications for post-extinction ecosystem recovery.
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Fu W, Jiang DY, Montañez IP, Meyers SR, Motani R, and Tintori A
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- Animals, Ecosystem, Extinction, Biological, Fossils, Paleontology, Reptiles, Carbon Cycle, Carbon Isotopes analysis, Seawater chemistry
- Abstract
The timing of marine ecosystem recovery following the End Permian Mass Extinction (EPME) remains poorly constrained given the lack of radiometric ages. Here we develop a high-resolution carbonate carbon isotope (δ(13)Ccarb) record for 3.20 million years of the Olenekian in South China that defines the astronomical time-scale for the critical interval of major evolutionary and oceanic events in the Spathian. δ(13)Ccarb documents eccentricity modulation of carbon cycling through the period and a strong obliquity signal. A shift in phasing between short and long eccentricity modulation, and amplification of obliquity, is nearly coincident with a 2% decrease in seawater δ(13)CDIC, the last of a longer-term stepped decrease through the Spathian. The mid-Spathian shift in seawater δ(13)CDIC to typical thermocline values is interpreted to record a major oceanic reorganization with global climate amelioration. Coincidence of the phasing shift with the first occurrence of marine reptiles (248.81 Ma), suggests that their invasion into the sea and the onset of a complex ecosystem were facilitated by restoration of deep ocean ventilation linked mechanistically to a change in the response of the oceanic carbon reservoir to astronomical forcing. Together these records place the first constraints on the duration of the post-extinction recovery to 3.35 myr.
- Published
- 2016
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19. Biocompatible and bioactive surface modifications for prolonged in vivo efficacy.
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Meyers SR and Grinstaff MW
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- Amino Acid Sequence, Animals, Biofouling prevention & control, Biomimetics, Coated Materials, Biocompatible adverse effects, Humans, Molecular Sequence Data, Prostheses and Implants adverse effects, Surface Properties, Time Factors, Coated Materials, Biocompatible chemistry
- Published
- 2012
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20. Bioactive stent surface coating that promotes endothelialization while preventing platelet adhesion.
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Meyers SR, Kenan DJ, Khoo X, and Grinstaff MW
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- Amino Acid Sequence, Blood Platelets drug effects, Cells, Cultured, Coated Materials, Biocompatible therapeutic use, Humans, Peptides, Coated Materials, Biocompatible pharmacology, Endothelial Cells drug effects, Platelet Adhesiveness drug effects, Stents
- Abstract
A bifunctional peptide coating was designed, synthesized, and evaluated as a potential pro-healing stent coating. The bifunctional peptide consisted of a short 28-mer sequence that on the N-terminus has a motif with affinity for polystyrene binding and at the C-terminus has a motif that was shown to bind selectively human endothelial cells but not platelets. Results showed that the selective coating, a polystyrene-binding peptide terminated in RRETAWA (FFSFFFPASAWGSSGSSGK(biotin)CRRETAWAC), bound endothelial cells quantitatively as well as the common RGD motif, but unlike RGD, it did not show any preference for platelet adherence. Follow-up work examining the difference in cell line selectivity between endothelial cells, whose binding should be encouraged, and smooth muscle cells, whose binding should be deprecated in a stenting application, did identify a temporal preference of the RRETAWA-terminated peptide coating for endothelial cells. However, the in vivo implications of this apparent selectivity need to be examined in more detail before definitive conclusions can be drawn. The positive in vitro results encourage the continued development of other novel coatings that mimic biological structures, signaling capabilities, or both to direct cellular processes on the surface of synthetic materials.
- Published
- 2011
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21. The development of peptide-based interfacial biomaterials for generating biological functionality on the surface of bioinert materials.
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Meyers SR, Khoo X, Huang X, Walsh EB, Grinstaff MW, and Kenan DJ
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- Amino Acid Sequence, Apoptosis, Biotin metabolism, Cell Adhesion, Cell Movement, Cell Proliferation, Cell Survival, Cells, Cultured, Coated Materials, Biocompatible, Endothelial Cells cytology, Endothelial Cells metabolism, Fluorescein-5-isothiocyanate metabolism, Humans, Microscopy, Atomic Force, Molecular Sequence Data, Peptides chemistry, Surface Properties, Biocompatible Materials metabolism, Materials Testing, Peptides metabolism, Polystyrenes metabolism
- Abstract
Biomaterials used in implants have traditionally been selected based on their mechanical properties, chemical stability, and biocompatibility. However, the durability and clinical efficacy of implantable biomedical devices remain limited in part due to the absence of appropriate biological interactions at the implant interface and the lack of integration into adjacent tissues. Herein, we describe a robust peptide-based coating technology capable of modifying the surface of existing biomaterials and medical devices through the non-covalent binding of modular biofunctional peptides. These peptides contain at least one material binding sequence and at least one biologically active sequence and thus are termed, "Interfacial Biomaterials" (IFBMs). IFBMs can simultaneously bind the biomaterial surface while endowing it with desired biological functionalities at the interface between the material and biological realms. We demonstrate the capabilities of model IFBMs to convert native polystyrene, a bioinert surface, into a bioactive surface that can support a range of cell activities. We further distinguish between simple cell attachment with insufficient integrin interactions, which in some cases can adversely impact downstream biology, versus biologically appropriate adhesion, cell spreading, and cell survival mediated by IFBMs. Moreover, we show that we can use the coating technology to create spatially resolved patterns of fluorophores and cells on substrates and that these patterns retain their borders in culture.
- Published
- 2009
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22. Anionic amphiphilic dendrimers as antibacterial agents.
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Meyers SR, Juhn FS, Griset AP, Luman NR, and Grinstaff MW
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- Anions chemistry, Anions pharmacology, Anti-Bacterial Agents chemistry, Bacillus subtilis drug effects, Dendrimers chemistry, Endothelial Cells drug effects, Humans, Microbial Sensitivity Tests, Octoxynol pharmacology, Sodium Dodecyl Sulfate pharmacology, Anti-Bacterial Agents pharmacology, Dendrimers pharmacology
- Abstract
An anionic amphiphilic dendrimer is reported that possesses increased cytotoxicological potency against prokaryotic cells compared to eukaryotic cells. The half-maximal effective concentration (EC50) for the dendrimer against Bacillus subtilis, a Gram-positive bacterial strain, was measured to be 4.1 x 10(-5) M, while that against human umbilical vein endothelial cells (HUVEC) was more than 36x greater at a value of 1.5 x 10(-3) M. EC50 ratios for two commercial amphiphiles, sodium dodecyl sulfate (SDS) and Triton X-100, in addition to a similar synthesized dendritic structure were at most only 3.8x greater. Furthermore, the observed EC50 values appear to be correlated to the critical aggregation constant (CAC) in solution suggesting a mechanism of action for these anionic amphiphilic dendrimers related to their supramolecular structures.
- Published
- 2008
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23. Enzymatic release of a surface-adsorbed RGD therapeutic from a cleavable peptide anchor.
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Meyers SR, Kenan DJ, and Grinstaff MW
- Subjects
- Adsorption, Animals, Biomimetics, Cell Adhesion, Enzymes chemistry, Humans, Kinetics, Peptides chemistry, Polystyrenes chemistry, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Substrate Specificity, Surface Properties, Drug Delivery Systems, Oligopeptides chemistry
- Published
- 2008
- Full Text
- View/download PDF
24. Peptide-PEG amphiphiles as cytophobic coatings for mammalian and bacterial cells.
- Author
-
Kenan DJ, Walsh EB, Meyers SR, O'Toole GA, Carruthers EG, Lee WK, Zauscher S, Prata CA, and Grinstaff MW
- Subjects
- Amino Acid Sequence, Bacterial Adhesion, Enzyme-Linked Immunosorbent Assay, Humans, Microscopy, Atomic Force, Molecular Sequence Data, Staphylococcus aureus physiology, Peptides chemistry, Polyethylene Glycols chemistry
- Abstract
Amphiphilic macromolecules containing a polystyrene-adherent peptide domain and a cell-repellent poly(ethylene glycol) domain were designed, synthesized, and evaluated as a cytophobic surface coating. Such cytophobic, or cell-repellent, coatings are of interest for varied medical and biotechnological applications. The composition of the polystyrene binding peptide domain was identified using an M13 phage display library. ELISA and atomic force spectroscopy were used to evaluate the binding affinity of the amphiphile peptide domain to polystyrene. When coated onto polystyrene, the amphiphile reduced cell adhesion of two distinct mammalian cell lines and pathogenic Staphylococcus aureus strains.
- Published
- 2006
- Full Text
- View/download PDF
25. Magnetic resonance imaging of defects in DeLancey's vaginal support levels I, II, and III.
- Author
-
Huddleston HT, Dunnihoo DR, Huddleston PM 3rd, and Meyers PC Sr
- Subjects
- Female, Humans, Urinary Incontinence, Stress surgery, Vagina surgery, Vaginal Diseases surgery, Magnetic Resonance Imaging, Urinary Incontinence, Stress etiology, Vagina pathology, Vaginal Diseases pathology
- Abstract
Objective: The aim was to demonstrate paravaginal defects at DeLancey's levels I, II, and III by pelvic magnetic resonance imaging scanning in patients with symptomatic pelvic relaxation preoperatively and to demonstrate the disappearance of such defects after surgical repair., Study Design: Magnetic resonance imaging scans of the pelvis were performed in 12 patients exhibiting cystourethroceles and symptomatic urinary stress incontinence., Results: Magnetic resonance imaging scans of bilateral fascial defects at the upper third of the vagina (level I) were unremarkable except for the constant "chevron sign," whereas the middle third of the vagina (level II) displayed the "saddlebags sign," and the lower third of the vagina (level III) displayed the "mustache sign." These defects disappeared postoperatively., Conclusions: Bilateral defects in the paracolpium at vaginal support levels I, II, and III may be found by magnetic resonance imaging scans before surgery in certain patients with symptomatic pelvic relaxation. Postoperative scans after paravaginal repair demonstrate the disappearance of these defects.
- Published
- 1995
- Full Text
- View/download PDF
26. Tuberculosis in Giraffe.
- Author
-
Meyers JC Sr
- Published
- 1892
27. Cotton-Seed Cakes.
- Author
-
Meyers JC Sr
- Published
- 1890
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