11,704 research outputs found
Recovery of lubricant base oils using ionic liquid processes
Two novel low-temperature ionic liquid processes are developed for the recovery of base oils from waste lubricant oils. One uses 3-(triethoxysilyl)-propylammonium-3-(triethoxysilyl)-propyl carbamate (TESAC), in which the waste lubricant base oil is insoluble, and the other uses trihexyl(tetradecyl)phosphonium chloride (P6,6,6,14Cl) in which the base oil is soluble. In the 3-aminopropyl-triethoxysilane (TESA)/TESAC process, waste oil components, including the base oil, are dissolved in the solvent TESA which is converted, in situ, with carbon dioxide to TESAC, recovering the base oil as an insoluble layer. In the P6,6,6,14Cl process, the base oil is separated from most additives as a solution in the ionic liquid from which it can be extracted with methanol. The recovered oils from both processes have properties consistent with lubricant oils in commercial use and the ionic liquids can be recovered for recycle minimising reagent use and providing a route to closed-loop base oil recovery and recycle
Quantitative magnetic resonance imaging traits as endophenotypes for genetic mapping in epilepsy.
Over the last decade, the field of imaging genomics has combined high-throughput genotype data with quantitative magnetic resonance imaging (QMRI) measures to identify genes associated with brain structure, cognition, and several brain-related disorders. Despite its successful application in different psychiatric and neurological disorders, the field has yet to be advanced in epilepsy. In this article we examine the relevance of imaging genomics for future genetic studies in epilepsy from three perspectives. First, we discuss prior genome-wide genetic mapping efforts in epilepsy, considering the possibility that some studies may have been constrained by inherent theoretical and methodological limitations of the genome-wide association study (GWAS) method. Second, we offer a brief overview of the imaging genomics paradigm, from its original inception, to its role in the discovery of important risk genes in a number of brain-related disorders, and its successful application in large-scale multinational research networks. Third, we provide a comprehensive review of past studies that have explored the eligibility of brain QMRI traits as endophenotypes for epilepsy. While the breadth of studies exploring QMRI-derived endophenotypes in epilepsy remains narrow, robust syndrome-specific neuroanatomical QMRI traits have the potential to serve as accessible and relevant intermediate phenotypes for future genetic mapping efforts in epilepsy
Development of an Expert System for Ultrasonic Flaw Classification
The complete characterization of a flaw requires information about the flaw type (crack, void, inclusion, etc.), flaw size, and orientation. Here we are only concerned with the determination of the flaw type so that the appropriate sizing algorithms can be chosen. This type of classification problem using ultrasonic waves is very suitable for employing the tools and techniques of artificial intelligence [1,2]. Adaptive learning methods, for example, have in the past been employed to train a flaw classification module so that it can distinguish between cracks and volumetric flaws [3]. Some of the limitations of this approach, however, have been due to the empirical nature of the features used for classification and the difficulty of understanding and adjusting the decision-making process when errors occur.</p
Global WEIRDing: Transitions in Wild Plant Knowledge and Treatment Preferences in Congo Hunter-Gatherers
Cultures around the world are converging as populations become more connected. On the one hand this increased connectedness can promote the recombination of existing cultural practices to generate new ones, but on the other it may lead to the replacement of traditional practices and global WEIRDing. Here we examine the process and causes of changes in cultural traits concerning wild plant knowledge in Mbendjele BaYaka hunter–gatherers from Congo. Our results show that the BaYaka who were born in town reported knowing and using fewer plants than the BaYaka who were born in forest camps. Plant uses lost in the town-born BaYaka related to medicine. Unlike the forest-born participants, the town-born BaYaka preferred Western medicine over traditional practices, suggesting that the observed decline of plant knowledge and use is the result of replacement of cultural practices with the new products of cumulative culture
Holocene lake sediment core sequences from Lochnagar, Cairngorm Mts., Scotland - UK final report for CHILL-10,000
The CHILL 10,000 research objective at Lochnagar is to examine proxy data for temperature
and climate conditions. Changes in lake sediment stratigraphical data can be used to reconstruct
past conditions. These proxies include organic and minerogenic matter as a bulk proxy for
catchment and within-lake productivity, chironomids as a proxy for air temperature, diatoms as
an indicator for lake water pH, pollen as an indicator of catchment vegetation and finally
biomarkers to help determine changes in proportions of organic source material within the lake
mud
Galaxy Harassment and the Evolution of Clusters of Galaxies
Disturbed spiral galaxies with high rates of star formation pervaded clusters
of galaxies just a few billion years ago, but nearby clusters exclude spirals
in favor of ellipticals. ``Galaxy harassment" (frequent high speed galaxy
encounters) drives the morphological transformation of galaxies in clusters,
provides fuel for quasars in subluminous hosts and leaves detectable debris
arcs. Simulated images of harassed galaxies are strikingly similar to the
distorted spirals in clusters at observed by the Hubble Space
Telescope.Comment: Submitted to Nature. Latex file, 7 pages, 10 photographs in gif and
jpeg format included. 10 compressed postscript figures and text available
using anonymous ftp from ftp://ftp-hpcc.astro.washington.edu/pub/hpcc/moore/
(mget *) Also available at http://www-hpcc.astro.washington.edu/papers
Fourth ventricle tumors in children: complications and influence of surgical approach
OBJECTIVES:
The goal of this study was to characterize the complications and morbidity related to the surgical management of pediatric fourth ventricle tumors.
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METHODS:
All patients referred to the authors’ institution with posterior fossa tumors from 2002 to 2018 inclusive were screened to include only true fourth ventricle tumors. Preoperative imaging and clinical notes were reviewed to extract data on presenting symptoms; surgical episodes, techniques, and adjuncts; tumor histology; and postoperative complications.
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RESULTS:
Three hundred fifty-four children with posterior fossa tumors were treated during the study period; of these, 185 tumors were in the fourth ventricle, and 167 fourth ventricle tumors with full data sets were included in this analysis. One hundred patients were male (mean age ± SD, 5.98 ± 4.12 years). The most common presenting symptom was vomiting (63.5%). The most common tumor types, in order, were medulloblastoma (94 cases) > pilocytic astrocytoma (30 cases) > ependymoma (30 cases) > choroid plexus neoplasms (5 cases) > atypical teratoid/rhabdoid tumor (4 cases), with 4 miscellaneous lesions. Of the 67.1% of patients who presented with hydrocephalus, 45.5% had an external ventricular drain inserted (66.7% of these prior to tumor surgery, 56.9% frontal); these patients were more likely to undergo ventriculoperitoneal shunt (VPS) placement at a later date (p = 0.00673). Twenty-two had an endoscopic third ventriculostomy, of whom 8 later underwent VPS placement. Overall, 19.7% of patients had a VPS sited during treatment.
Across the whole series, the transvermian approach was more frequent than the telovelar approach (64.1% vs 33.0%); however, the telovelar approach was significantly more common in the latter half of the series (p < 0.001). Gross-total resection was achieved in 70.7%. The most common postoperative deficit was cerebellar mutism syndrome (CMS; 28.7%), followed by new weakness (24.0%), cranial neuropathy (18.0%), and new gait abnormality/ataxia (12.6%). Use of intraoperative ultrasonography significantly reduced the incidence of CMS (p = 0.0365). There was no significant difference in the rate of CMS between telovelar or transvermian approaches (p = 0.745), and multivariate logistic regression modeling did not reveal any statistically significant relationships between CMS and surgical approach.
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CONCLUSIONS:
Surgical management of pediatric fourth ventricle tumors continues to evolve, and resection is increasingly performed through the telovelar route. CMS is enduringly the major postoperative complication in this patient population
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