539 research outputs found
Core drill's bit is replaceable without withdrawal of drill stem - A concept
Drill bit is divided into several sectors. When collapsed, the outside diameter is forced down the drill stem, when it reaches bottom the sectors are forced outward and form a cutting bit. A dulled bit is retracted by reversal of this procedure
Torsionally rigid and thermally stable boom
Design of rigid thermally stable beryllium copper extendible boom for space application
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Lamb's Self-Revelations as "Elia"
The purpose of this thesis is to determine the nature of Charles Lamb as revealed in his Elia essays. To this end, these essays form the major portion of the text. The general procedure for ascertaining what these excerpts indicate is as follows: first, the characteristics of Charles Lamb are determined from a study of the Elia essays; second, these characteristics are considered in relation to information derived from biographies. Careful attention is given to significant discrepancies between the essays and other sources
Gustatory Function of Patients With and Without Cholesteatoma Undergoing Middle Ear Surgery
Objective: To compare measured and perceived taste function before and after surgery of patients with chronic otitis media with cholesteatoma (OMCC) to patients without cholesteatoma (patients with chronic suppurative otitis media [CSOM] and patients with lateral skull base lesions [LSB]). Methods: This prospective cohort study included 29 patients undergoing surgery for unilateral OMCC. The chorda tympani nerve (CTN) was resected in 8 of these patients. Fourteen patients undergoing surgery for unilateral CSOM and 5 patients undergoing surgery for unilateral LSB (with CTN resection) served as the comparison group. Taste function was measured using taste strips on both sides of the tongue before surgery, 2âweeks postoperatively and 3âmonths postoperatively. The affected side of the tongue was compared to the unaffected side. A questionnaire on taste perception was completed at each visit. Results: Preoperatively, cholesteatoma patients showed higher taste strip scores than non-cholesteatoma patients, indicating a larger difference between the healthy and affected sides of the tongue. Despite this difference in measured taste function few cholesteatoma patients reported taste alteration before surgery (3/29 [10.3%]). Postoperatively, patients with CTN resection (OMCC patients with CTN resection and LSB patients) showed a decreased measured taste function. Subjectively, only approximately 20% of these patients reported taste alteration 3âmonths postoperatively. Conclusions: Before surgery, cholesteatoma patients displayed an impaired measured taste function compared to patients without cholesteatoma (CSOM, LSB). Subjectively this was often unnoticed. After surgery, despite removal of the CTN and consequent reduction of measured taste function, few patients reported taste alteration and subjective taste perception was seen to be improving. In regards to middle ear surgery, perceived taste function does not seem to reflect measured gustatory function
The growing and vital role of botanical gardens in climate change research.
Botanical gardens make unique contributions to climate change research, conservation, and public engagement. They host unique resources, including diverse collections of plant species growing in natural conditions, historical records, and expert staff, and attract large numbers of visitors and volunteers. Networks of botanical gardens spanning biomes and continents can expand the value of these resources. Over the past decade, research at botanical gardens has advanced our understanding of climate change impacts on plant phenology, physiology, anatomy, and conservation. For example, researchers have utilized botanical garden networks to assess anatomical and functional traits associated with phenological responses to climate change. New methods have enhanced the pace and impact of this research, including phylogenetic and comparative methods, and online databases of herbarium specimens and photographs that allow studies to expand geographically, temporally, and taxonomically in scope. Botanical gardens have grown their community and citizen science programs, informing the public about climate change and monitoring plants more intensively than is possible with garden staff alone. Despite these advances, botanical gardens are still underutilized in climate change research. To address this, we review recent progress and describe promising future directions for research and public engagement at botanical gardens.Publisher versio
Favorable Climate Change Response Explains Non-Native Species' Success in Thoreau's Woods
Invasive species have tremendous detrimental ecological and economic impacts. Climate change may exacerbate species invasions across communities if non-native species are better able to respond to climate changes than native species. Recent evidence indicates that species that respond to climate change by adjusting their phenology (i.e., the timing of seasonal activities, such as flowering) have historically increased in abundance. The extent to which non-native species success is similarly linked to a favorable climate change response, however, remains untested. We analyzed a dataset initiated by the conservationist Henry David Thoreau that documents the long-term phenological response of native and non-native plant species over the last 150 years from Concord, Massachusetts (USA). Our results demonstrate that non-native species, and invasive species in particular, have been far better able to respond to recent climate change by adjusting their flowering time. This demonstrates that climate change has likely played, and may continue to play, an important role in facilitating non-native species naturalization and invasion at the community level
Creative Citizen Science Illuminates Complex Ecological Responses to Climate Change
Climate change is causing the timing of key behaviors (i.e., phenology) to shift differently across trophic levels and among some interacting organisms (e.g., plants and pollinators, predators and prey), suggesting that interactions among species are being disrupted (1, 2). Studying the phenology of interactions, however, is difficult, which has limited researchersâ ability to zero in on changes in specific interactions or on the consequences of mismatches. In PNAS, Hassall et al. (3) use a combination of citizen science techniques to investigate the effects of climate change on dozens of specific interactions. They focus on a Batesian mimicry complex involving stinging bees and wasps, stingless syrphid flies (also known as hoverflies) that mimic their appearance, and avian predators. The methods used by Hassall et al. (3) continue an upsurge of innovations in climate change ecology research, in which the role of citizen science is expanding to provide new approaches to complex challenges
The Strength of Migratory Connectivity for Birds En Route to Breeding Through the Gulf of Mexico
The strength of migratory connectivity is a measure of the cohesion of populations among phases of the annual cycle, including breeding, migration, and wintering. Many NearcticâNeotropical species have strong migratory connectivity between breeding and wintering phases of the annual cycle. It is less clear if this strength persists during migration when multiple endogenous and exogenous factors may decrease the cohesion of populations among routes or through time along the same routes. We sampled three bird species, American redstart Setophaga ruticilla, ovenbird Seiurus aurocapilla, and wood thrush Hylocichla mustelina, during spring migration through the Gulf of Mexico region to test if breeding populations differentiate spatially among migration routes or temporally along the same migration routes and the extent to which withinâpopulation timing is a function of sex, age, and carryâover from winter habitat, as measured by stable carbon isotope values in claws (ÎŽ13C). To make quantitative comparisons of migratory connectivity possible, we developed and used new methodology to estimate the strength of migratory connectivity (MC) from probabilistic origin assignments identified using stable hydrogen isotopes in feathers (ÎŽ2H). We found support for spatial differentiation among routes by American redstarts and ovenbirds and temporal differentiation along routes by American redstarts. After controlling for breeding origin, the timing of American redstart migration differed among ages and sexes and ovenbird migration timing was influenced by carryâover from winter habitat. The strength of migratory connectivity did not differ among the three species, with each showing weak breedingâtoâspring migration MC relative to prior assessments of breedingâwintering connectivity. Our work begins to fill an essential gap in methodology and understanding of the extent to which populations remain together during migration, information critical for a full annual cycle perspective on the population dynamics and conservation of migratory animals
Biodiversity Gains? The Debate on Changes in Local- vs Global-Scale Species Richness
Editorial: Do changes in biodiversity at local scales reflect the declines seen at global scales? This debate dates back at least 15 years..
An immunocompetent farmer with isolated cerebral alveolar echinococcosis: illustrative case
BACKGROUND: Alveolar echinococcosis is a rare condition, but living or working in a rural environment is a substantial risk factor. The liver is the organ primarily affected, with additional extrahepatic manifestations in approximately 25% of cases. Primary extrahepatic disease is rare, and isolated cerebral involvement is extremely unusual.
OBSERVATIONS: The authors described an illustrative case of isolated cerebral alveolar echinococcosis in an immunocompetent farmer. Magnetic resonance imaging of the brain showed a predominantly cystic lesion with perifocal edema and a âbunch of grapesâ appearance in the left frontal lobe. Histology revealed sharply demarcated fragments of a fibrous cyst wall accompanied by marked inflammation and necrosis. Higher magnification showed remnants of protoscolices with hooklets and calcified corpuscles. Immunohistochemistry and polymerase chain reaction (PCR) analysis confirmed the diagnosis of cerebral alveolar echinococcosis. Interestingly, serology and thoracic and abdominal computed tomography results were negative, indicative of an isolated primary extrahepatic manifestation.
LESSONS: Isolated, primary central nervous system echinococcosis is extremely rare, with only isolated case reports. As in the authorsâ case, it can occur in immunocompetent patients, especially persons with a rural vocational history. Negative serology results do not exclude cerebral echinococcosis, which requires histological confirmation. Immunohistochemical staining and PCR analysis are especially useful in cases without classic morphological findings
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