1,723 research outputs found

    Consistent Earnings Growth and the Credibility of Management Forecasts

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    This paper examines the relation between a series of past earnings increases and the credibility of voluntary management earnings forecasts. We demonstrate that both analyst forecast revisions and stock price reactions around management earnings forecasts that contain good news are more pronounced when the firm has posted a string of recent earnings increases. These results are consistent with our primary hypothesis that voluntary management earnings forecasts are more believable when they are made by firms with a history of consistent growth in earnings. This effect is more pronounced when firms are not widely followed by analysts. Additional analysis suggests that management forecasts are more accurate relative to ex post realized earnings when made by a firm with consistent growth in prior earnings. The effect of prior earnings growth on the credibility of management earnings forecasts is reduced when the level of net assets suggests a history of prior earnings management

    Spike-timing control by dendritic plateau potentials in the presence of synaptic barrages

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    Apical and tuft dendrites of pyramidal neurons support regenerative electrical potentials, giving rise to long-lasting (approximately hundreds of milliseconds) and strong (~50 mV from rest) depolarizations. Such plateau events rely on clustered glutamatergic input, can be mediated by calcium or by NMDA currents, and often generate somatic depolarizations that last for the time course of the dendritic plateau event. We address the computational significance of such single-neuron processing via reduced but biophysically realistic modeling. We introduce a model based on two discrete integration zones, a somatic and a dendritic one, that communicate from the dendritic to the somatic compartment via a long plateau-conductance. We show principled differences in the way dendritic vs. somatic inhibition controls spike timing, and demonstrate how this could implement a mechanism of spike time control in the face of barrages of synaptic inputs

    TurbuStat: Turbulence Statistics in Python

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    We present TurbuStat (v1.0): a Python package for computing turbulence statistics in spectral-line data cubes. TurbuStat includes implementations of fourteen methods for recovering turbulent properties from observational data. Additional features of the software include: distance metrics for comparing two data sets; a segmented linear model for fitting lines with a break-point; a two-dimensional elliptical power-law model; multi-core fast-fourier-transform support; a suite for producing simulated observations of fractional Brownian Motion fields, including two-dimensional images and optically-thin HI data cubes; and functions for creating realistic world coordinate system information for synthetic observations. This paper summarizes the TurbuStat package and provides representative examples using several different methods. TurbuStat is an open-source package and we welcome community feedback and contributions.Comment: Accepted in AJ. 21 pages, 8 figure

    Physiology of Layer 5 Pyramidal Neurons in Mouse Primary Visual Cortex: Coincidence Detection through Bursting

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    L5 pyramidal neurons are the only neocortical cell type with dendrites reaching all six layers of cortex, casting them as one of the main integrators in the cortical column. What is the nature and mode of computation performed in mouse primary visual cortex (V1) given the physiology of L5 pyramidal neurons? First, we experimentally establish active properties of the dendrites of L5 pyramidal neurons of mouse V1 using patch-clamp recordings. Using a detailed multi-compartmental model, we show this physiological setup to be well suited for coincidence detection between basal and apical tuft inputs by controlling the frequency of spike output. We further show how direct inhibition of calcium channels in the dendrites modulates such coincidence detection. To establish the singe-cell computation that this biophysics supports, we show that the combination of frequency-modulation of somatic output by tuft input and (simulated) calcium-channel blockage functionally acts as a composite sigmoidal function. Finally, we explore how this computation provides a mechanism whereby dendritic spiking contributes to orientation tuning in pyramidal neurons

    Litter identity affects assimilation of carbon and nitrogen by a shredding caddisfly

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    Ecologists often equate litter quality with decomposition rate. In soil and sediments, litter that is rapidly decomposed by microbes often has low concentrations of tannin and lignin and low C:N ratios. Do these same traits also favor element transfer to higher trophic levels in streams, where many insects depend on litter as their primary food source? We test the hypothesis that slow decomposition rates promote element transfer from litter to insects, whereas rapid decomposition favors microbes. We measured carbon and nitrogen fluxes from four plant species to a leaf-shredding caddisfly using isotopically labeled litter. Caddisflies assimilated a higher percentage of litter carbon and nitrogen lost from slowly decomposing litters (Platanus wrightii and Quercus gambelii). In contrast, rapidly decomposing litters (Fraxinus velutina and Populus fremontii) supported higher microbial biomass. These results challenge the view that rapidly decomposing litter is higher quality by demonstrating that slowly decomposing litters provide a critical resource for insects

    A Prospective Program to Reduce the Clinical Incidence of Clostridium Difficile Colitis Infection after Cystectomy

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    Purpose The development of Clostridium difficile infection after cystectomy is associated with significant morbidity and mortality. We implemented a prospective screening program to identify asymptomatic carriers of Clostridium difficile and assessed its impact on clinical Clostridium difficile infection rates compared to historical matched controls. Materials and Methods Prospective Clostridium Difficile screening prior to cystectomy began in March 2015. The 380 consecutive patients undergoing cystectomy prior to initiation of screening (control cohort) were matched based on 5 clinical factors with the 386 patients who underwent cystectomy from March 2015 to December 2017 (trial cohort). Screened positive patients were placed in contact isolation and treated prophylactically with Metronidazole. Multivariable models were built on an intention-to-screen and an effectiveness of screening basis to determine if screening reduced the rates of symptomatic Clostridium Difficile infections postoperatively. Results With the implementation of the screening protocol, Clostridium difficile infections rates declined from 9.4 to 5.5% (OR 0.52, p=0.0268) on an intention-to-screen protocol and from 9.2 to 4.9% on an effectiveness of screening protocol (OR 0.46, p=0.0174). Conclusions Clostridium difficile screening prior to cystectomy is associated with a significant decrease in rates of clinically symptomatic infections postoperatively. These results should be confirmed in a randomized controlled trial

    Interventions to reduce stress and prevent burnout in healthcare professionals supported by digital applications: a scoping review

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    Aim: Healthcare professionals are at increased risk of burnout, primarily due to workplace-related stressors. The COVID-19 pandemic has further increased this risk. Different interventions exist with varying degrees of effectiveness; little is reported on the content and implementation of such programs. This review fills this gap, with attention to recent programs using digital components. Methods: PubMed, Embase, PsycInfo, and Google Scholar were searched between January 24th and 28th, 2022, limited to the last 5 years (≥2017). Articles were included if they (1) focused on stress reduction or burnout prevention for nurses and medical doctors within workplace health promotion for nurses or medical doctors, (2) included a digital program component, (3) were conducted in high-income country contexts, and (4) were clinical studies published in English or German. Data was extracted using a priori designed spreadsheets. A group of at least 2 authors at each stage carried out the screening, selection, and data extraction. Results: The search strategy identified 153 articles, all except 7 were excluded. Two studies were conducted in the USA, two in Spain, one in the Netherlands, Poland, and Korea each. Four studies used a randomized study design, all but one had a control group. A wide range of outcome measures was used. The types of interventions included an adapted mindfulness-based stress reduction program combined with aspects of behavioral therapies, cognitive behavioral therapy, or acceptance and commitment therapy. The digital components used were apps (4 studies), a digital platform, blended learning, and a web-based intervention (1 study each). Six studies focused on individual interventions, one included organizational interventions. Conclusion: Despite an acute burnout crisis in the healthcare sector, only seven recent interventions were found that integrated digital components. Several problems emerged during the implementation of the interventions that made it clear that organizational support is urgently needed for successful implementation. Although interventions for stress reduction and burnout prevention should combine individual and organizational measures to be as successful as possible, this was only partially the case in one of the intervention programs. The results of this scoping review can be used to further develop or optimize stress and burnout prevention programs

    The turbulent gas structure in the centers of NGC253 and the Milky Way

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    We compare molecular gas properties in the starbursting center of NGC253 and the Milky Way Galactic Center (GC) on scales of ~1-100 pc using dendograms and resolution-, area- and noise-matched datasets in CO (1-0) and CO (3-2). We find that the size-line width relations in NGC253 and the GC have similar slope, but NGC253 has larger line widths by factors of ~2-3. The σ2/R\sigma^2/R dependency on column density shows that, in the GC, on scales of 10-100 pc the kinematics of gas over N>3×1021N>3\times10^{21} cm−2^{-2} are compatible with gravitationally bound structures. In NGC253 this is only the case for column densities N>3×1022N>3\times10^{22} cm−2^{-2}. The increased line widths in NGC253 originate in the lower column density gas. This high-velocity dispersion, not gravitationally self-bound gas is likely in transient structures created by the combination of high average densities and feedback in the starburst. The high densities turns the gas molecular throughout the volume of the starburst, and the injection of energy and momentum by feedback significantly increases the velocity dispersion at a given spatial scale over what is observed in the GC.Comment: 13 pages, 3 figures, 4 tables; accepted for publication in the Astrophysical Journa
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