873 research outputs found

    A Survey of Aquatic Invertebrate Communities in Nebraska Sandhill Lakes Reveals Potential Alternative Ecosystem States

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    Aquatic invertebrate communities are important to shallow lake ecosystem form and function, providing vital components to the food web and thereby important to achieving lake management goals. We characterized lake invertebrate communities and physicochemical variables in six Nebraska Sandhill lakes and examined these characteristics within an alternative stable state framework. Surveys were conducted during 2005 within each of these lakes by sampling aquatic macroinvertebrate abundance, zooplankton abundance and biomass, phytoplankton biomass, and physicochemical variables. When placed within an alternative stable state framework, the response variables exhibited a gradient of different ecosystem states. Two lakes appeared congruent with the clear water state (dense submergent vegetation, high invertebrate abundance and diversity, and low phytoplankton), two lakes were congruent with the turbid water state (high phytoplankton, low vegetation coverage, and low invertebrate abundance and diversity), and two lakes were intermediate, likely in a state of hysteresis (i.e., multiple states under equal environmental conditions). Principal component groupings further supported these findings by following similar lakespecific patterns with attributes of each stable state grouping meaningfully according to the observed lake states. The lakes contained varied fish communities, potentially influencing many measured metrics, through a top-down mechanism. Generally, lakes dominated by piscivorous fish displayed the clear water state, whereas lakes with abundant planktivores displayed the turbid water state. Shallow lakes containing dense invertebrate communities likely provide a rich food base to important fauna (migratory waterfowl) that aid in reaching desired management objectives for these systems. Multiple small lakes, in proximity, displaying divergent ecosystem states invites the opportunity for more in-depth analyses of driving mechanisms that will undoubtedly add to our ability to effectively manage these systems in the future

    The State of Self-Organized Criticality of the Sun During the Last Three Solar Cycles. II. Theoretical Model

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    The observed powerlaw distributions of solar flare parameters can be interpreted in terms of a nonlinear dissipative system in the state of self-organized criticality (SOC). We present a universal analytical model of a SOC process that is governed by three conditions: (i) a multiplicative or exponential growth phase, (ii) a randomly interrupted termination of the growth phase, and (iii) a linear decay phase. This basic concept approximately reproduces the observed frequency distributions. We generalize it to a randomized exponential-growth model, which includes also a (log-normal) distribution of threshold energies before the instability starts, as well as randomized decay times, which can reproduce both the observed occurrence frequency distributions and the scatter of correlated parametyers more realistically. With this analytical model we can efficiently perform Monte-Carlo simulations of frequency distributions and parameter correlations of SOC processes, which are simpler and faster than the iterative simulations of cellular automaton models. Solar cycle modulations of the powerlaw slopes of flare frequency distributions can be used to diagnose the thresholds and growth rates of magnetic instabilities responsible for solar flares.Comment: Part II of Paper I: The State of Self-Organized Criticality of the Sun During the Last Three Solar Cycles. I. Observation

    Modeling the transition from decompensated to pathological hypertrophy

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    Background--Long-chain acyl-CoA synthetases (ACSL) catalyze the conversion of long-chain fatty acids to fatty acyl-CoAs. Cardiac-specific ACSL1 temporal knockout at 2 months results in a shift from FA oxidation toward glycolysis that promotes mTORC1-mediated ventricular hypertrophy. We used unbiased metabolomics and gene expression analyses to examine the early effects of genetic inactivation of fatty acid oxidation on cardiac metabolism, hypertrophy development, and function. Methods and Results--Global cardiac transcriptional analysis revealed differential expression of genes involved in cardiac metabolism, fibrosis, and hypertrophy development in Acsl1 H-/- hearts 2 weeks after Acsl1 ablation. Comparison of the 2- and 10-week transcriptional responses uncovered 137 genes whose expression was uniquely changed upon knockdown of cardiac ACSL1, including the distinct upregulation of fibrosis genes, a phenomenon not observed after complete ACSL1 knockout. Metabolomic analysis identified metabolites altered in hearts displaying partially reduced ACSL activity, and rapamycin treatment normalized the cardiac metabolomic fingerprint. Conclusions--Short-term cardiac-specific ACSL1 inactivation resulted in metabolic and transcriptional derangements distinct from those observed upon complete ACSL1 knockout, suggesting heart-specific mTOR (mechanistic target of rapamycin) signaling that occurs during the early stages of substrate switching. The hypertrophy observed with partial Acsl1 ablation occurs in the context of normal cardiac function and is reminiscent of a physiological process, making this a useful model to study the transition from physiological to pathological hypertrophy

    Perioperative opioid prescriptions associated with stress incontinence and pelvic organ prolapse surgery

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    Background: There is an opioid epidemic in the United States with a contributing factor of opioids being prescribed for postoperative pain after surgery. Objective: Among women who underwent stress urinary incontinence and pelvic organ prolapse surgeries, our primary objective was to determine the proportion of women who filled perioperative opioid prescriptions and to compare factors associated with these opioid prescriptions. We also sought to assess the risk of prolonged opioid use through 1 year after stress urinary incontinence and pelvic organ prolapse surgeries. Study Design: Using a population-based cohort of commercially insured individuals in the 2005–2015 IBM MarketScan databases, we identified opioid-naive women ≥18 years who underwent stress urinary incontinence and/or pelvic organ prolapse procedures based on Current Procedural Terminology codes. We defined the perioperative period as the window beginning 30 days before surgery extending until 7 days after surgery. Any filled opioid prescription in this window was considered a perioperative prescription. For our primary outcome, we reported the proportion of opioid-naive women who filled a perioperative opioid prescription and reported the median quantity dispensed in the perioperative period. We also assessed demographic and perioperative factors associated with perioperative opioid prescription fills. Previous studies have defined prolonged use as the proportion of women who fill an opioid prescription between 90 and 180 days after surgery. We report this estimate as well as continuous opioid use, defined as the proportion of women with ongoing monthly opioid prescriptions filled through 1 year after stress urinary incontinence and/or pelvic organ prolapse surgery. Results: Among the 217,460 opioid-naive women who underwent urogynecologic surgery, 61,025 (28.1%) had pelvic organ prolapse and stress urinary incontinence surgeries, 85,575 (39.4%) had stress urinary incontinence surgery without pelvic organ prolapse surgery, and 70,860 (32.6%) had pelvic organ prolapse surgery without stress urinary incontinence surgery. Overall, 167,354 (77.0%) filled a perioperative opioid prescription, and the median quantity was 30 pills (interquartile range, 20–30). In a multivariate regression model, younger age, pelvic organ prolapse surgery with or without stress urinary incontinence surgery, abdominal route, hysterectomy, and mesh use remained significantly associated with opioid prescriptions filled. Among those with a filled perioperative opioid prescription, the risk of prolonged use defined as an opioid prescription filled between 90 and 180 days was 7.5% (95% confidence interval, 7.3–7.6). However, the risk of prolonged use defined as continuous use with at least 1 monthly opioid prescription filled after surgery was significantly lower: 1.2% (1.13–1.24), 0.32% (0.29–0.35), 0.06% (0.05–0.08), and 0.04% (0.02–0.05) at 60, 90, 180, and 360 days after surgery, respectively. Conclusion: Among privately insured, opioid-naive women undergoing stress urinary incontinence and/or pelvic organ prolapse surgery, 77% of women filled an opioid prescription with a median of 30 opioid pills prescribed. For prolonged use, 7.5% (95% confidence interval, 7.3–7.6) filled an opioid prescription within 90 to 180 days after surgery, but the rates of continuously filled opioid prescriptions were significantly lower at 0.06% (95% confidence interval, 0.05–0.08) at 180 days and 0.04% (95% confidence interval, 0.02–0.05) at 1 year after surgery

    Persistent Opioid Use after Hysterectomy in the United States, 2005-2015

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    OBJECTIVE:To assess variables associated with opioid prescriptions filled perioperatively after hysterectomy and the risk of prolonged opioid use through 1 year after hysterectomy.METHODS:In this retrospective cohort study, we used the 2005-2015 IBM MarketScan databases to identify women aged at least 18 years who underwent hysterectomy. For opioid use, we identified filled prescriptions for opioid medications. We excluded women with prevalent opioid use, defined as an opioid prescription filled 180 to 30 days preoperatively or at least two prescriptions filled in the 30 days before surgery. We defined perioperative opioid use as any opioid prescription filled within 30 days before or 7 days after surgery. We used log-binomial regression to identify independent predictors of perioperative opioid prescription fill. To assess the risk of long-term opioid use, we estimated the proportion of women with ongoing monthly opioid prescriptions through 12 months after surgery and the proportion of women with any opioid prescription 3-6 months after surgery, mimicking published estimates.RESULTS:Among 569,634 women who underwent hysterectomy during the study period, 176,537 (30.9%) were excluded owing to prevalent opioid use. We found that 331,322 (84.3%) women filled a perioperative opioid prescription, with median quantity of 30 pills (interquartile range 25-40), and that younger (adjusted risk ratio [adjRR]18-24 0.91) and older (adjRR65-74 0.84; adjRR75+ 0.70) patients were less likely to receive a perioperative prescription compared with women aged 45-54. The proportion of women with continuous monthly fills of opioids through 2, 3, 6, and 12 months after surgery was 1.40%, 0.34%, 0.06%, and 0.02%, respectively.CONCLUSION:Most women who underwent hysterectomy in the United States from 2005 to 2015 filled a perioperative opioid prescription with a median quantity of 30 pills. The risk of prolonged opioid use through 6 months is quite low, at 0.06% or 1 in 1,547

    Society for Endocrinology UK guidance on the initial evaluation of an infant or an adolescent with a suspected disorder of sex development (Revised 2015)

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    It is paramount that any child or adolescent with a suspected disorder of sex development (DSD) is assessed by an experienced clinician with adequate knowledge about the range of conditions associated with DSD. If there is any doubt, the case should be discussed with the regional DSD team. In most cases, particularly in the case of the newborn, the paediatric endocrinologist within the regional team acts commonly as the first point of contact. This clinician should be part of a multidisciplinary team experienced in management of DSD and should ensure that the affected person and parents have access to specialist psychological support and that their information needs are comprehensively addressed. The underlying pathophysiology of DSD and the strengths and weaknesses of the tests that can be performed should be discussed with the parents and affected young person and tests undertaken in a timely fashion. Finally, in the field of rare conditions, it is imperative that the clinician shares the experience with others through national and international clinical and research collaboration

    Clinical Evidence Supports a Protective Role for CXCL5 in Coronary Artery Disease

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    Our goal was to measure the association of CXCL5 and molecular phenotypes associated with coronary atherosclerosis severity in patients at least 65 years old. CXCL5 is classically defined as a proinflammatory chemokine, but its role in chronic inflammatory diseases, such as coronary atherosclerosis, is not well defined. We enrolled individuals who were at least 65 years old and undergoing diagnostic cardiac catheterization. Coronary artery disease (CAD) severity was quantified in each subject via coronary angiography by calculating a CAD score. Circulating CXCL5 levels were measured from plasma, and both DNA genotyping and mRNA expression levels in peripheral blood mononuclear cells were quantified via microarray gene chips. We observed a negative association of CXCL5 levels with CAD at an odds ratio (OR) of 0.46 (95% CI, 0.27–0.75). Controlling for covariates, including sex, statin use, hypertension, hyperlipidemia, obesity, self-reported race, smoking, and diabetes, the OR was not significantly affected [OR, 0.54 (95% CI, 0.31–0.96)], consistent with a protective role for CXCL5 in coronary atherosclerosis. We also identified 18 genomic regions with expression quantitative trait loci of genes correlated with both CAD severity and circulating CXCL5 levels. Our clinical findings are consistent with the emerging link between chemokines and atherosclerosis and suggest new therapeutic targets for CAD

    A new calibrated sunspot group series since 1749: statistics of active day fractions

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    Although the sunspot-number series have existed since the mid-19th century, they are still the subject of intense debate, with the largest uncertainty being related to the "calibration" of the visual acuity of individual observers in the past. Daisy-chain regression methods are applied to inter-calibrate the observers which may lead to significant bias and error accumulation. Here we present a novel method to calibrate the visual acuity of the key observers to the reference data set of Royal Greenwich Observatory sunspot groups for the period 1900-1976, using the statistics of the active-day fraction. For each observer we independently evaluate their observational thresholds [S_S] defined such that the observer is assumed to miss all of the groups with an area smaller than S_S and report all the groups larger than S_S. Next, using a Monte-Carlo method we construct, from the reference data set, a correction matrix for each observer. The correction matrices are significantly non-linear and cannot be approximated by a linear regression or proportionality. We emphasize that corrections based on a linear proportionality between annually averaged data lead to serious biases and distortions of the data. The correction matrices are applied to the original sunspot group records for each day, and finally the composite corrected series is produced for the period since 1748. The corrected series displays secular minima around 1800 (Dalton minimum) and 1900 (Gleissberg minimum), as well as the Modern grand maximum of activity in the second half of the 20th century. The uniqueness of the grand maximum is confirmed for the last 250 years. It is shown that the adoption of a linear relationship between the data of Wolf and Wolfer results in grossly inflated group numbers in the 18th and 19th centuries in some reconstructions

    Computer modeling of diabetes and Its transparency: a report on the Eighth Mount Hood Challenge

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    Objectives The Eighth Mount Hood Challenge (held in St. Gallen, Switzerland, in September 2016) evaluated the transparency of model input documentation from two published health economics studies and developed guidelines for improving transparency in the reporting of input data underlying model-based economic analyses in diabetes. Methods Participating modeling groups were asked to reproduce the results of two published studies using the input data described in those articles. Gaps in input data were filled with assumptions reported by the modeling groups. Goodness of fit between the results reported in the target studies and the groups’ replicated outputs was evaluated using the slope of linear regression line and the coefficient of determination (R2). After a general discussion of the results, a diabetes-specific checklist for the transparency of model input was developed. Results Seven groups participated in the transparency challenge. The reporting of key model input parameters in the two studies, including the baseline characteristics of simulated patients, treatment effect and treatment intensification threshold assumptions, treatment effect evolution, prediction of complications and costs data, was inadequately transparent (and often missing altogether). Not surprisingly, goodness of fit was better for the study that reported its input data with more transparency. To improve the transparency in diabetes modeling, the Diabetes Modeling Input Checklist listing the minimal input data required for reproducibility in most diabetes modeling applications was developed. Conclusions Transparency of diabetes model inputs is important to the reproducibility and credibility of simulation results. In the Eighth Mount Hood Challenge, the Diabetes Modeling Input Checklist was developed with the goal of improving the transparency of input data reporting and reproducibility of diabetes simulation model results
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