29 research outputs found

    The United States COVID-19 Forecast Hub dataset

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    Academic researchers, government agencies, industry groups, and individuals have produced forecasts at an unprecedented scale during the COVID-19 pandemic. To leverage these forecasts, the United States Centers for Disease Control and Prevention (CDC) partnered with an academic research lab at the University of Massachusetts Amherst to create the US COVID-19 Forecast Hub. Launched in April 2020, the Forecast Hub is a dataset with point and probabilistic forecasts of incident cases, incident hospitalizations, incident deaths, and cumulative deaths due to COVID-19 at county, state, and national, levels in the United States. Included forecasts represent a variety of modeling approaches, data sources, and assumptions regarding the spread of COVID-19. The goal of this dataset is to establish a standardized and comparable set of short-term forecasts from modeling teams. These data can be used to develop ensemble models, communicate forecasts to the public, create visualizations, compare models, and inform policies regarding COVID-19 mitigation. These open-source data are available via download from GitHub, through an online API, and through R packages

    Facile Synthesis of AuPd Nanochain Networks on Carbon Supports and Their Application as Electrocatalysts for Oxygen Reduction Reaction

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    The present work reports the facile synthesis and characterization of carbon-supported porous Pd shell coated Au nanochain networks (AuPdNNs/C). By using Co nanoframes as sacrificial templates, AuPdNNs/C series have been prepared by a two-step galvanic replacement reaction (GRR) technique. In the first step, the Au metal precursor, HAuCl4, reacts spontaneously with the formed Co nanoframes through the GRR, resulting in Au nanochain networks (AuNNs). The second GRR is performed with various concentrations of Pd precursor (0.1, 1, and 10mM PdCl2), resulting in AuPdNNs/C. The synthesized AuPdNNs/C series are investigated as electrocatalysts for oxygen reduction reaction (ORR) in alkaline solution. The physical properties of the AuPdNNs/C catalysts are characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV-vis absorption spectroscopy, and cyclic voltammetry (CV). Rotating disk electrode (RDE) voltammetric studies show that the Au0.8Pd0.2NNs/C (prepared using 1mM PdCl2) has the highest ORR activity among all the AuPdNNs/C series, which is comparable to commercial Pt catalyst (E-TEK). The ORR activity of AuPdNNs/C is presumably due to the enhanced Pd surface area and high porosity of Pd nanoshells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

    Influence of Ca-doping in layered perovskite PrBaCo2O5+delta on the phase transition and cathodic performance of a solid oxide fuel cell

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    Layered perovskite oxides with the formula LnBaCo(2)O(5+delta) (Ln = Pr, Nd, Sm and Gd) have received attention as promising cathode materials for solid oxide fuel cells (SOFCs) because of their high oxygen diffusion and surface exchange coefficients. Recently, many researchers have reported that substituting barium with strontium or calcium can increase the structural stability, electrical conductivity, and catalytic activity of LnBaCo(2)O(5+delta). In this study, we investigated the effect of Ca doping on the structural, electrical, and electrochemical properties of PrBa1-xCaxCo2O5+delta (x = 0, 0.1, 0.2, 0.3 and 0.4). Increasing the amount of Ca dopant changed the structure of PrBa1-xCaxCo2O5+delta from a layered perovskite to a simple perovskite. At x = 0.3, co-existence of the simple and the layered perovskite structure is observed. Electrical conductivity and electro-chemical performance were improved with increasing amount of Ca in the layered perovskite structure and declined with increasing amount of the simple perovskite phase.clos

    Flexible, Transparent, and Noncytotoxic Graphene Electric Field Stimulator for Effective Cerebral Blood Volume Enhancement

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    Enhancing cerebral blood volume (CBV) of a targeted area without causing side effects is a primary strategy for treating cerebral hypoperfusion. Here, we report a new nonpharmaceutical and nonvascular surgical method to increase CBV. A flexible, transparent, and skin-like biocompatible graphene electrical field stimulator was placed directly onto the cortical brain, and a noncontact electric field was applied at a specific local blood vessel. Effective CBV increases in the blood vessels of mouse brains were directly observed from <i>in vivo</i> optical recordings of intrinsic signal imaging. The CBV was significantly increased in arteries of the stimulated area, but neither tissue damage nor unnecessary neuronal activation was observed. No transient hypoxia was observed. This technique provides a new method to treat cerebral blood circulation deficiencies at local vessels and can be applied to brain regeneration and rehabilitation

    Determining Exposure Factors of Anti-Fogging, Dye, Disinfectant, Repellent, and Preservative Products in Korea

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    Reliable exposure factors are essential to determine health risks posed by chemicals in consumer products. We analyzed five risk-concerned product categories (anti-fogging, dye, disinfectant, repellent, and preservative products) for 13 products (three car anti-fogging products, a lens anti-fogging product, two car dye products, two drain disinfectants, an air conditioner disinfectant, a chlorine-based disinfectant, a fabric repellent, an insect repellent for food, and a wood preservative) considered to be of high risk in order to determine exposure factors via web surveys and estimation of amount of product. Among the 3000 participants (1482 (49%) men) aged ≥19 years, drain disinfectants were used most frequently (38.2%); the rate of usage of the other products ranged between 1.1–24.0%. The usage rates for the consumer products differed by sex, age, income, and education. Some consumer products such as car and lens anti-fogging products, chlorine-based disinfectants, fabric repellents, and drain disinfectants were regularly used more than once a month, while car dye products, air conditioner disinfectants, insect repellents for food, and wood preservatives were not regularly used owing to the specific product purposes and seasonal needs. Our results could be used for managing or controlling chemical substances in consumer products and conducting accurate exposure assessments

    Cerebral Hemodynamics and Vascular Reactivity in Mild and Severe Ischemic Rodent Middle Cerebral Artery Occlusion Stroke Models

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    Ischemia can cause decreased cerebral neurovascular coupling, leading to a failure in the autoregulation of cerebral blood flow. This study aims to investigate the effect of varying degrees of ischemia on cerebral hemodynamic reactivity using in vivo realtime optical imaging. We utilized direct cortical stimulation to elicit hyper-excitable neuronal activation, which leads to induced hemodynamic changes in both the normal and middle cerebral artery occlusion (MCAO) ischemic stroke groups. Hemodynamic measurements from optical imaging accurately predict the severity of occlusion in mild and severe MCAO animals. There is neither an increase in cerebral blood volume nor in vessel reactivity in the ipsilateral hemisphere (I.H) of animals with severe MCAO. The pial artery in the contralateral hemisphere (C.H) of the severe MCAO group reacted more slowly than both hemispheres in the normal and mild MCAO groups. In addition, the arterial reactivity of the I.H in the mild MCAO animals was faster than the normal animals. Furthermore, artery reactivity is tightly correlated with histological and behavioral results in the MCAO ischemic group. Thus, in vivo optical imaging may offer a simple and useful tool to assess the degree of ischemia and to understand how cerebral hemodynamics and vascular reactivity are affected by ischemia. © Experimental Neurobiology 2016.2

    Efficient Mitochondrial Genome Editing by CRISPR/Cas9

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    The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 system has been widely used for nuclear DNA editing to generate mutations or correct specific disease alleles. Despite its flexible application, it has not been determined if CRISPR/Cas9, originally identified as a bacterial defense system against virus, can be targeted to mitochondria for mtDNA editing. Here, we show that regular FLAG-Cas9 can localize to mitochondria to edit mitochondrial DNA with sgRNAs targeting specific loci of the mitochondrial genome. Expression of FLAG-Cas9 together with gRNA targeting Cox1 and Cox3 leads to cleavage of the specific mtDNA loci. In addition, we observed disruption of mitochondrial protein homeostasis following mtDNA truncation or cleavage by CRISPR/Cas9. To overcome nonspecific distribution of FLAG-Cas9, we also created a mitochondria-targeted Cas9 (mitoCas9). This new version of Cas9 localizes only to mitochondria; together with expression of gRNA targeting mtDNA, there is specific cleavage of mtDNA. MitoCas9-induced reduction of mtDNA and its transcription leads to mitochondrial membrane potential disruption and cell growth inhibition. This mitoCas9 could be applied to edit mtDNA together with gRNA expression vectors without affecting genomic DNA. In this brief study, we demonstrate that mtDNA editing is possible using CRISPR/Cas9. Moreover, our development of mitoCas9 with specific localization to the mitochondria should facilitate its application for mitochondrial genome editing
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