115 research outputs found

    Particle image velocimetry and modelling of horizontal coherent liquid jets impinging on and draining down a vertical wall

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    The flow patterns created by a coherent horizontal liquid jet impinging on a vertical wall at moderate flow rates (jet flowrates 0.5-4.0 L min-1, jet velocities 2.6-21 m s-1) are studied with water on glass, polypropylene and polymethylmethacrylate (acrylic, PerspexÂź) using a novel particle image velicometry (PIV) technique employing nearly opaque liquid doped with artificial pearlescence to track surface velocity. Flow patterns similar to those reported in previous studies are observed on each substrate: their dimensions differed owing to the influence of wall material on contact angle. The dimensions are compared with models for (i) the radial flow zone, reported by Wang et al. (2013b), and (ii) the part of the draining film below the jet impingement point where it narrows to a node. For (ii), the model presented by Mertens et al. (2005) is revised to include a simpler assumed draining film shape and an alternative boundary condition accounting for surface tension effects acting at the film edge. This revised model gives equally good or better fits to the experimental data as compared with the Mertens et al. model. The effective contact angle which gives good agreement with the data is found to lie between the measured quasi-static advancing and receding contact angles, at approximately half the advancing value. The PIV measurements confirmed the existence of a thin, fast moving film with radial flow surrounding the point of impingement, and a wide draining film bounded by ropes of liquid below the impingement point. While these measurements generally support the predictions of existing models, these models assume that the flow is steady. In contrast, surface waves were evident in both regions and this partly explains the difference between the measured surface velocity and the values estimated from the models.The apparatus was constructed by Tao Wang and Lee Pratt. Preparatory work by Huifeng Wu, and Nevile Research Fellowship for JRL from Magdalene College, Cambridge, are gratefully acknowledged.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.expthermflusci.2015.12.01

    Cognitive Task Demands Modulate the Sensitivity of the Human Cochlea

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    Recent studies lead to the conclusion that focused attention, through the activity of corticofugal and medial olivocochlear (MOC) efferent pathways, modulates activity at the most peripheral aspects of the auditory system within the cochlea. In two experiments, we investigated the effects of different intermodal attention manipulations on the response of outer hair cells (OHCs), and the control exerted by the MOC efferent system. The effect of the MOCs on OHC activity was characterized by measuring the amplitude and rapid adaptation time course of distortion product otoacoustic emissions (DPOAEs). In the first, DPOAE recordings were compared while participants were reading a book and counting the occurrence of the letter “a” (auditory-ignoring) and while counting either short- or long-duration eliciting tones (auditory-attending). In the second, DPOAEs were recorded while subjects watched muted movies with subtitles (auditory-ignoring/visual distraction) and were compared with DPOAEs recorded while subjects counted the same tones (auditory-attending) as in Experiment 1. In both Experiments 1 and 2, the absolute level of the averaged DPOAEs recorded during the auditory-ignoring condition was statistically higher than that recorded in the auditory-attending condition. Efferent-induced rapid adaptation was evident in all DPOAE contours, under all attention conditions, suggesting that two medial efferent processes act independently to determine rapid adaptation, which is unaffected by attention, and the overall DPOAE level, which is significantly affected by changes in the focus of attention

    Measuring exercise in eating disorder patients : a Delphi study to aggregate clinical and research knowledge

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    Background: Exercise is a prominent feature of most eating disorders, and has been shown to have a number of detrimental effects on treatment outcome. There is some disagreement in the literature regarding the construct of compulsive exercise, and assessment and treatment varies significantly. This study therefore aimed to aggregate expert clinicians’ and researchers’ views on how to define and measure compulsive exercise in eating disorder patients. The expert panel was also asked about questionnaire design, and possible problems when measuring compulsive exercise. Method: This study used the Delphi method to establish consensus amongst an expert panel. Three successive rounds of questionnaires were distributed to the panel over a period of six months. The first round consisted of four open-ended questions regarding the definition and measurement of compulsive exercise in eating disorder patients. For Round 2, 70 statements were derived from the answers, and panelists were asked to rate each item on a Likert-based scale. An 85% consensus level was chosen. In Round 3, 44 statements were re-rated by the panel. Results: Seventeen of 24 participants completed all three rounds of the study. Consensus was achieved for 63% of the items, while 18.5% reached near consensus, and 18.5% did not reach consensus after Round 3. The panel agreed on a number of important aspects of compulsive exercise. Several suggestions regarding the format of a questionnaire assessing this behavior were also endorsed. The panel further identified common difficulties when assessing compulsive exercise in eating disorder patients, notably a lack of consensus still apparent in the literature. Conclusion: The current findings constitute a further step towards a unified definition of compulsive exercise, and contribute important suggestions to the measurement of this behavior

    Operative Management of Symptomatic, Metachronous Carotid Body Tumors Involving the Skull Base and Its Neurological Sequelae

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    A 44-year-old morbidly obese woman with a history of right carotid body tumor (CBT) resection presented with a symptomatic, nonfunctional, left Shamblin-III CBT. Abutment of the skull base precluded distal internal carotid artery control for arterial reconstruction, favoring parent vessel sacrifice after an asymptomatic provocative test. She underwent CBT resection with anticipated sacrifice of cranial nerves X and XII and the common carotid artery and its branches, developing baroreceptor failure syndrome and sequelae of cranial nerve sacrifice. When facing a symptomatic, metachronous CBT abutting the skull base, upfront operative intervention with adjuvant radiation for residual tumor optimizes curative resection

    Beirut explosion: TNT equivalence from the fireball evolution in the first 170 milliseconds

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    The evolution of the fireball resulting from the August 2020 Beirut explosion is traced using amateur videos taken during the first 400 ms after the detonation. Thirty-nine frames separated by 16.66–33.33 ms are extracted from six different videos located precisely on the map. Time evolution of the shock wave radius is traced by the fireball at consecutive time moments until about t≈170t≈170 ms and a distance d≈128d≈128 m. Pixel scales for the videos are calibrated by de-projecting the existing grain silos building, for which accurate as-built drawings are available, using the length, the width, and the height and by defining the line-of-sight incident angles. In the distance range d≈d≈ 60–128 m from the explosion center, the evolution of the fireball follows the Sedov–Taylor model with spherical geometry and an almost instantaneous energy release. This model is used to derive the energy available to drive the shock front at early times. Additionally, a drag model is fitted to the fireball evolution until its stopping at a time t≈500t≈500 ms at a distance d≈145±5d≈145±5 m. Using the derived TNT equivalent yield, the scaled stopping distance reached by the fireball and the shock wave-fireball detachment epoch within which the fireball is used to measure the shock wave are in excellent agreement with other experimental data. A total TNT equivalence of 200±80t200±80t at a distance d≈130d≈130 m is found. Finally, the dimensions of the crater size taken from a hydrographic survey conducted 6 days after the explosion are scaled with the known correlation equations yielding a close range of results. A recent published article by Dewey (Shock Waves 31:95–99, 2021) shows that the Beirut explosion TNT equivalence is an increasing function of distance. The results of the current paper are quantitatively in excellent agreement with this finding. These results present an argument that the actual mass of ammonium nitrate that contributed to the detonation is much less than the quantity that was officially claimed available

    Superfluid to normal phase transition and extreme regularity of superdeformed bands

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    We derive the exact semiclassical expression for the second inertial parameter B\cal B for the superfluid and normal phases. Interpolation between these limiting values shows that the function B(I){\cal B}(I) changes sign at the spin IcI_c, which is critical for a rotational spectrum. The quantity B\cal B turns out to be a sensitive measure of the change in static pairing correlations. The superfluid-to-normal transition reveals itself in the specific variation of the ratio B/A{\cal B}/{\cal A} versus spin II with the plateau characteristic of the normal phase. We find this dependence to be universal for normal deformed and superdeformed bands. The long plateau with a small value B/A∌A−8/3{\cal B}/{\cal A}\sim A^{-8/3} explains the extreme regularity of superdeformed bands.Comment: 30 pages in LaTeX, 6 figures (PostScript). To be published in Yadernaya Fizika (Physics of Atomic Nuclei), special edition dedecated to the 90th birthday of Prof. I. I. Gurevit

    Risk factors for tuberculosis treatment failure, default, or relapse and outcomes of retreatment in Morocco

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    <p>Abstract</p> <p>Background</p> <p>Patients with tuberculosis require retreatment if they fail or default from initial treatment or if they relapse following initial treatment success. Outcomes among patients receiving a standard World Health Organization Category II retreatment regimen are suboptimal, resulting in increased risk of morbidity, drug resistance, and transmission.. In this study, we evaluated the risk factors for initial treatment failure, default, or early relapse leading to the need for tuberculosis retreatment in Morocco. We also assessed retreatment outcomes and drug susceptibility testing use for retreatment patients in urban centers in Morocco, where tuberculosis incidence is stubbornly high.</p> <p>Methods</p> <p>Patients with smear- or culture-positive pulmonary tuberculosis presenting for retreatment were identified using clinic registries in nine urban public clinics in Morocco. Demographic and outcomes data were collected from clinical charts and reference laboratories. To identify factors that had put these individuals at risk for failure, default, or early relapse in the first place, initial treatment records were also abstracted (if retreatment began within two years of initial treatment), and patient characteristics were compared with controls who successfully completed initial treatment without early relapse.</p> <p>Results</p> <p>291 patients presenting for retreatment were included; 93% received a standard Category II regimen. Retreatment was successful in 74% of relapse patients, 48% of failure patients, and 41% of default patients. 25% of retreatment patients defaulted, higher than previous estimates. Retreatment failure was most common among patients who had failed initial treatment (24%), and default from retreatment was most frequent among patients with initial treatment default (57%). Drug susceptibility testing was performed in only 10% of retreatment patients. Independent risk factors for failure, default, or early relapse after initial treatment included male gender (aOR = 2.29, 95% CI 1.10-4.77), positive sputum smear after 3 months of treatment (OR 7.14, 95% CI 4.04-13.2), and hospitalization (OR 2.09, 95% CI 1.01-4.34). Higher weight at treatment initiation was protective. Male sex, substance use, missed doses, and hospitalization appeared to be risk factors for default, but subgroup analyses were limited by small numbers.</p> <p>Conclusions</p> <p>Outcomes of retreatment with a Category II regimen are suboptimal and vary by subgroup. Default among patients receiving tuberculosis retreatment is unacceptably high in urban areas in Morocco, and patients who fail initial tuberculosis treatment are at especially high risk of retreatment failure. Strategies to address risk factors for initial treatment default and to identify patients at risk for failure (including expanded use of drug susceptibility testing) are important given suboptimal retreatment outcomes in these groups.</p

    Structural sustainability appraisal in BIM

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    The provision of Application Programming Interface (API) in BIM-enable tools can contribute to facilitating BIM-related research. APIs are useful links for running plug-ins and external programmes but they are yet to be fully exploited in expanding the BIM scope. The modelling of n-Dimensional (nD) building performance measures can potentially benefit from BIM extension through API implementations. Sustainability is one such measure associated with buildings. For the structural engineer, recent design criteria have put great emphasis on the sustainability credentials as part of the traditional criteria of structural integrity, constructability and cost. This paper examines the utilization of API in BIM extension and presents a demonstration of an API application to embed sustainability issues into the appraisal process of structural conceptual design options in BIM. It concludes that API implementations are useful in expanding the BIM scope. Also, the approach including process modelling, algorithms and object-based instantiations demonstrated in the API implementation can be applicable to other nD building performance measures as may be relevant to the various professional platforms in the construction domain

    Noun and verb knowledge in monolingual preschool children across 17 languages: Data from cross-linguistic lexical tasks (LITMUS-CLT)

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    This article investigates the cross-linguistic comparability of the newly developed lexical assessment tool Cross-linguistic Lexical Tasks (LITMUS-CLT). LITMUS-CLT is a part the Language Impairment Testing in Multilingual Settings (LITMUS) battery (Armon-Lotem, de Jong & Meir, 2015). Here we analyse results on receptive and expressive word knowledge tasks for nouns and verbs across 17 languages from eight different language families: Baltic (Lithuanian), Bantu (isiXhosa), Finnic (Finnish), Germanic (Afrikaans, British English, South African English, German, Luxembourgish, Norwegian, Swedish), Romance (Catalan, Italian), Semitic (Hebrew), Slavic (Polish, Serbian, Slovak) and Turkic (Turkish). The participants were 639 monolingual children aged 3;0-6;11 living in 15 different countries. Differences in vocabulary size were small between 16 of the languages; but isiXhosa-speaking children knew significantly fewer words than speakers of the other languages. There was a robust effect of word class: accuracy was higher for nouns than verbs. Furthermore, comprehension was more advanced than production. Results are discussed in the context of cross-linguistic comparisons of lexical development in monolingual and bilingual populations
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