2,367 research outputs found

    Experimental dynamic stiffness and damping of externally pressurized gas-lubricated journal bearings

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    A rigid vertical shaft was operated with known amounts of unbalance at speeds to 30,000 rpm and gas supply pressure ratios to 4.8. From measured amplitude and phase angle data, dynamic stiffness and damping coefficients of the bearings were determined. The measured stiffness was proportional to the supply pressure, while damping was little affected by supply pressure. Damping dropped rapidly as the fractional frequency whirl threshold was approached. A small-eccentricity analysis overpredicted the stiffness by 20 to 70 percent. Predicted damping was lower than measured at low speeds but higher at high speeds

    Poo Power: Revisiting Biogas Generation Potential on Dairy Farms in Texas

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    Biogas created from anaerobic digestion on dairy farms can be used to generate electricity, produce coproducts, and reduce reliance on off-farm inputs. We incorporate risk into simulation models representing dairy farms in Texas and demonstrate the profitability of new anaerobic digester installation. Based on this market, results indicate projects that have low investment costs, receive grant support for construction, utilize coproducts, or have some combination of these factors have higher net present value at the end of the study period; however, even with generous grant support and high electricity prices, projects with average investment costs remain unprofitable

    The Challenge of Climate Change Adaptation for Agriculture: an Economically Oriented Review

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    Climate change is occurring. Deviations from historic temperatures and precipitation plus increased frequency of extreme events are modifying agriculture systems globally. Adapting agricultural management practices offers a way to lessen the effects or exploit opportunities. Herein many aspects of the adaptation issue are discussed, including needs, strategies, observed actions, benefits, economic analysis approaches, role of public/private actors, limits, and project evaluation. We comment on the benefits and shortcomings of analytical methods and suggested economic efforts. Economists need to play a role in such diverse matters as projecting adaptation needs, designing adaptation incentives, and evaluating projects to ensure efficiency and effectiveness

    Science-based restoration monitoring of coastal habitats, Volume One: A framework for monitoring plans under the Estuaries and Clean Waters Act of 2000 (Public Law 160-457)

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    Executive Summary: The Estuary Restoration Act of 2000 (ERA), Title I of the Estuaries and Clean Waters Act of 2000, was created to promote the restoration of habitats along the coast of the United States (including the US protectorates and the Great Lakes). The NOAA National Centers for Coastal Ocean Science was charged with the development of a guidance manual for monitoring plans under this Act. This guidance manual, titled Science-Based Restoration Monitoring of Coastal Habitats, is written in two volumes. It provides technical assistance, outlines necessary steps, and provides useful tools for the development and implementation of sound scientific monitoring of coastal restoration efforts. In addition, this manual offers a means to detect early warnings that the restoration is on track or not, to gauge how well a restoration site is functioning, to coordinate projects and efforts for consistent and successful restoration, and to evaluate the ecological health of specific coastal habitats both before and after project completion (Galatowitsch et al. 1998). The following habitats have been selected for discussion in this manual: water column, rock bottom, coral reefs, oyster reefs, soft bottom, kelp and other macroalgae, rocky shoreline, soft shoreline, submerged aquatic vegetation, marshes, mangrove swamps, deepwater swamps, and riverine forests. The classification of habitats used in this document is generally based on that of Cowardin et al. (1979) in their Classification of Wetlands and Deepwater Habitats of the United States, as called for in the ERA Estuary Habitat Restoration Strategy. This manual is not intended to be a restoration monitoring “cookbook” that provides templates of monitoring plans for specific habitats. The interdependence of a large number of site-specific factors causes habitat types to vary in physical and biological structure within and between regions and geographic locations (Kusler and Kentula 1990). Monitoring approaches used should be tailored to these differences. However, even with the diversity of habitats that may need to be restored and the extreme geographic range across which these habitats occur, there are consistent principles and approaches that form a common basis for effective monitoring. Volume One, titled A Framework for Monitoring Plans under the Estuaries and Clean Waters Act of 2000, begins with definitions and background information. Topics such as restoration, restoration monitoring, estuaries, and the role of socioeconomics in restoration are discussed. In addition, the habitats selected for discussion in this manual are briefly described. (PDF contains 116 pages

    Bicyclic Boronate β-Lactamase Inhibitors: The Present Hope against Deadly Bacterial Pathogens

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    The use of β-lactamase inhibitors in combination with β-lactam antibiotics is an emerging area in drug discovery. This strategy allows the restoration of the therapeutic efficacy of these antibiotics in clinical use against multiresistant bacteria. These pathogens are drug resistant because they express β-lactamase enzymes, which prevent the antibiotic therapeutic action by catalyzing the hydrolysis of the β-lactam ring. These enzymes are quite diverse in both their structural architecture and hydrolytic capability, as well as in the mechanism of action. The ever-increasing emergence of pathogens that are capable of coproducing different types of β-lactamases has triggered the search for ultrabroad-spectrum inhibitors capable of deactivating both serine- and metallo-β-lactamases. A recent breakthrough in this long-pursued and unmet need is the discovery of bicyclic boronate inhibitors, specifically taniborbactam, VNRX-7145, and QPX7728, which are currently under clinical development in combination with cefepime, ceftibuten, and QPX2014, respectively. The present article highlights the therapeutic potential of these inhibitors and their spectrum of efficacy is compared with those of other β-lactam/β-lactamase inhibitor combinations recently approved by the food and drug administration. The molecular basis of the ultrabroad-spectrum of activity of boron-based inhibitors is also discussed, on the basis of the available crystal structures and the results of computational studiesinancial support from the Spanish Ministry of Economy and Competiveness (SAF2016-75638-R, PID2019-105512RB-I00), the Xunta de Galicia [ED431B 2018/04 and Centro singular de investigación de Galicia accreditation 2019–2022 (ED431G 2019/03)], and the European Regional Development Fund (ERDF) is gratefully acknowledgedS

    Effects of radiofrequency electromagnetic fields (RF EMF) on cancer in laboratory animal studies

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    Background: The carcinogenicity of radiofrequency electromagnetic fields (RF EMF) has been evaluated by the International Agency for Research on Cancer (IARC) in 2011. Based on limited evidence of carcinogenicity in humans and in animals, RF EMF were classified as possibly carcinogenic to humans (Group 2B). In 2018, based on a survey amongst RF experts, WHO prioritized six major topics of potential RF EMF related human health effects for systematic reviews. In the current manuscript, we present the protocol for the systematic review of experimental laboratory animal studies (cancer bioassays) on exposure to RF fields on the outcome of cancer in laboratory animals. Objective: In the framework of WHO's Radiation Program, the aim of this work is to systematically evaluate effects of RF EMF exposure on cancer in laboratory animals. Study eligibility and criteria: WHO's Handbook (2014) for guideline development will be followed with appropriate adaptation. The selection of eligible studies will be based on Population, Exposures, Comparators, and Outcomes (PECO) criteria. We will include peer-reviewed articles and publicly available reports from government agencies reporting original data about animal cancer bioassays on exposure to RF EMF. The studies are identified by searching the following databases: MEDLINE (PubMed), Science Citation Index Expanded and Emerging Sources Citation Indes (Web of Science), Scopus, and the EMF Portal. No language or year-of-publication restrictions are applied. The methods and results of eligible studies will be presented in accordance with the PRISMA 2020 guidelines. Study appraisal method: Study evaluation of individual studies will be assessed using a risk of bias (RoB) tool developed by the Office of Health Assessment and Translation (OHAT) with appropriate considerations including sensitivity for evaluating RF EMF exposure in animal cancer bioassays. The final evaluation on the certainty of the evidence on a carcinogenic risk of RF EMF exposure in experimental animals will be performed using the OHAT Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach with appropriate considerations. The protocol has been registered in an open-source repository (PROSPERO)

    Effect of parasympathetic stimulation on brain activity during appraisal of fearful expressions

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    Autonomic nervous system activity is an important component of human emotion. Mental processes influence bodily physiology, which in turn feeds back to influence thoughts and feelings. Afferent cardiovascular signals from arterial baroreceptors in the carotid sinuses are processed within the brain and contribute to this two-way communication with the body. These carotid baroreceptors can be stimulated non-invasively by externally applying focal negative pressure bilaterally to the neck. In an experiment combining functional neuroimaging (fMRI) with carotid stimulation in healthy participants, we tested the hypothesis that manipulating afferent cardiovascular signals alters the central processing of emotional information (fearful and neutral facial expressions). Carotid stimulation, compared with sham stimulation, broadly attenuated activity across cortical and brainstem regions. Modulation of emotional processing was apparent as a significant expression-by-stimulation interaction within left amygdala, where responses during appraisal of fearful faces were selectively reduced by carotid stimulation. Moreover, activity reductions within insula, amygdala, and hippocampus correlated with the degree of stimulation-evoked change in the explicit emotional ratings of fearful faces. Across participants, individual differences in autonomic state (heart rate variability, a proxy measure of autonomic balance toward parasympathetic activity) predicted the extent to which carotid stimulation influenced neural (amygdala) responses during appraisal and subjective rating of fearful faces. Together our results provide mechanistic insight into the visceral component of emotion by identifying the neural substrates mediating cardiovascular influences on the processing of fear signals, potentially implicating central baroreflex mechanisms for anxiolytic treatment targets
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