33659 research outputs found
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Identification of Hard Ticks in the United States: A Practical Guide for Clinicians and Pathologists
No full textAccording to guidelines published by the Infectious Disease Society of America, Lyme disease prophylaxis is possible if a tick can be identified as Ixodes scapularis (nymphal or adult) within 72 hours of tick removal. However, a recent survey of medical practitioners indicates generally poor proficiency in tick identification. In this study, we provide a simple, practical guide to aid medical practitioners in identifying the most commonly encountered human biting ticks of North America
How do technological innovations affect corporate investment and hiring?
No full textIn this paper, we study the relation between technological advancement, and corporate investment and hiring. We build a corporate investment model with dynamic technology conditions, and we find the optimal investment and labor inputs increase in response to technological innovation shocks. Consistent with the model predictions, we empirically show that corporate investment and hiring increase following technological advancements, using various measures of technological innovation. Further, we find the effect is stronger for firms in more innovative industry, firms with higher capital intensity and firms with higher market-to-book ratio. Our findings provide evidence for the endogenous growth theory, i.e., firms with successful innovations tend to expand in capital investment and employment, suggesting technological innovations are, to some extent, Hicks-neutral
Immediate Post-Concussion and Cognitive Testing (ImPACT): Effects of Data Integration Strategies on Classification Accuracy
No full textObjective: The current study aimed to evaluate varying data integration procedures and their effects on the classification accuracy of Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT). Setting: Data were collected from an independent secondary school that included students in grades 9 to 12. Participants: The study examined 300 consecutive ImPACT score reports generated by secondary school students between 2010 and 2015. Design: To appraise ImPACT\u27s utility as a serialized measure, standardized regression-based equations were formulated to compute reliable change index scores. Discriminant function analyses (DFAs) consisting of varying combinations of ImPACT composite scores were conducted and their accuracy was compared to that produced by the standard interpretive procedure. Main Measures: Varying combinations of scores produced on Verbal Memory, Visual Memory, Visual Motor Speed, Reaction Speed, and the Postconcussion Symptom Scale were included in analyses. Results: DFAs yielded sensitivities ranging from 31% to 49%, specificities from 88% to 95%, positive predictive values (PPVs) from 61% to 83%, and negative predictive values (NPVs) from 67% to 75%. Conversely, the standard interpretive procedure yielded a sensitivity of 73%, specificity of 43%, PPV of 45%, and NPV of 72%. Conclusion: The standard interpretive procedure produced a higher sensitivity than the DFAs; however, its PPV did not exceed chance levels. Conversely, DFA equations produced superior PPVs; however, their sensitivity hovered around 50%, leaving a substantial proportion of individuals with concussion undetected. Cognitive composite scores did not appear to offer significant incremental utility in relation to symptom self-report. Base rate conditions and psychometric factors appeared to contribute to ImPACT\u27s limited classification accuracy
Loneliness before and during the COVID-19 pandemic—are unpartnered and childless older adults at higher risk?
Get PDFCOVID-19 mitigation efforts had the potential to exacerbate loneliness among older adults, particularly for the unpartnered or childless, yet specific studies on loneliness among these groups during the COVID-19 pandemic are lacking. Using data from the Survey of Health, Ageing and Retirement in Europe (SHARE) collected before (October 2019–March 2020) and during the pandemic (June–August 2020), we examine two loneliness outcomes: (1) “have you felt lonely recently?” (both datasets) and (2) “have you felt lonelier than before the pandemic?” (2020), and examine differences by partnership and parenthood status. Before COVID-19, those who lacked one tie but had the other (unpartnered parents or partnered childless) were at highest loneliness risk. During COVID-19, unpartnered and childless—especially unpartnered—remain at higher risk for loneliness, entering loneliness, and not “exiting” loneliness. We discuss these findings in light of family norms and needs in pandemic and non-pandemic times and provide recommendations for future research
Development and Application of a Supramolecular Brønsted Acid Catalyst Based on the Noria Macrocycle
No full textThe synthesis of derivatives of the Noria macrocycle and the structurally similar macrocycle, R3, each containing 12 sulfonic acid groups, is reported. Herein, we demonstrate their utility as reusable Brønsted acid catalysts for the Biginelli synthesis of dihydropyrimidinones and the Pechmann synthesis of coumarins. We also demonstrate that the supramolecular structure directs the reagents to interact with the sulfonic acid catalytic sites, thus increasing the catalyst\u27s efficiency compared to other monomeric, macrocyclic, and polymeric sulfonic acid catalysts
Difluorophosphoric Acid Generation and Crossover Reactions in LiNixCoyMnzO2 Cathodes Operating at High Voltage
Get PDFCycling lithiated metal oxides to high potential (\u3e4.5 V vs Li) is of significant interest for the next generation of lithium ion batteries as this significantly increases the capacity and energy of cells. However, cells cycled to high potential suffer from rapid capacity fade due to a combination of thickening of the anode solid electrolyte interphase (SEI) and impedance growth on the cathode. While transition metal catalysed degradation of the anode SEI has been widely proposed as a primary source of capacity loss, a related acid induced degradation of the anode SEI is proposed. A systematic investigation of LiNi0.5Co0.2Mn0.3O2, and LiNi0.8Co0.1Mn0.1O2 cathodes cycled to 4.2 and 4.6 V has been conducted and the oxidative generation of the strong acid difluorophosphoric acid (F2PO2H) has been quantified by solution Nuclear Magnetic Resonance (NMR) spectroscopy. Ex-situ surface analysis of the electrodes with X-ray Photo Electron spectroscopy (XPS) suggests that the generation of F2PO2H correlates with a thickening of the anode SEI and an increase in the fluorophosphate content of the SEI. Changes to the LiNi0.8Co0.1Mn0.1O2 surface for cells cycled to 4.6 V are also consistent with the generation of acidic species. There is good correlation between the concentration F2PO2H, anode SEI degradation and the capacity loss of the cells
Performance Improvement of Lithium Metal Batteries Enabled By LiBF3CN as a New Electrolyte Additive
Get PDFA newly synthesized electrolyte additive, lithium trifluoro(cyano) borate (LiBF3CN), has been investigated for electrochemical performance improvement of lithium metal batteries. The LiBF3CN has a structure where one fluorine atom of BF4− is substituted with a cyano group (−CN) prepared by the reaction of boron trifluoride etherate with lithium cyanide. The electrochemical performance in symmetric Li/Li cells and NCM523/Li cells is significantly improved upon the incorporation of LiBF3CN as an electrolyte additive into a carbonate-based electrolyte. Extensive characterization of the deposited lithium metal reveals that a thin (≈20 nm) and robust SEI composed of LiNxOy, Li3N and Li2O is formed by the reductive decomposition of the LiBF3CN additive, which plays an important role in decreasing the resistance and stabilizing lithium deposition/stripping. The insight into the substitution effect of a functional group obtained from this work provides guidance for the design of new electrolyte additives
Evaluating the Effect of Electrolyte Additive Functionalities on NMC622/Si Cell Performance
No full textUnstable electrode/electrolyte interface is the major cause of degradation for silicon (Si)-based anodes for lithium (Li)-ion batteries. Development of functional electrolyte additives can provide a viable path toward stabilizing the dynamic Si/electrolyte interface, which will benefit the development of high energy density Li-ion batteries. Here, we evaluate polymerizable electrolyte additives with varying functional groups (fluorocarbon, thiophosphate, and fluorophosphazene). The additives are examined using LiNi0.6Mn0.2Co0.2O2/Si full cells where the cycle performance and impedance are measured. Electrochemical tests show that the fluorine-containing additives provide better passivation at the Si electrode, leading to enhanced full cell performance. Among the three additives examined, best electrochemical performance is observed from the fluorocarbon-containing compound, followed by fluorophosphazene- and thiophosphate-containing compounds. Characterization of the solid electrolyte interphase (SEI) on cycled electrodes using Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) reveal that higher concentration of fluorine and lithium oxide, and lower concentration of carbonate and organic species correlate with enhanced electrochemical performance
Political Control, Corporate Governance and Firm Value: The Case of China
No full textWe examine whether requiring a Party committee to lead corporate governance at listed state-owned enterprises (SOEs) affects firm value in China. We find that the market reacts positively to the inclusion of Party leadership in SOEs\u27 governance structure and that the prospect of a crackdown on SOE corruption is likely to be the reason. The China governance model is strikingly different from other known models, and our findings suggest that a convergence of the corporate governance system of different countries due to globalization might not be the only outcome
