607 research outputs found

    Flight of the Vampire: Ontogenetic Gait-Transition in \u3cem\u3eVampyroteuthis Infernalis\u3c/em\u3e (Cephalopoda: Vampyromorpha)

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    Vampyroteuthis infernalis is a cosmopolitan cephalopod that lives in the oxygen minimum layer between 600 and 800 m depth. Morphometric and physiological studies have indicated that V. infernalis has little capacity for jet propulsion and has the lowest metabolic rate ever measured for a cephalopod. Because fin swimming is inherently more efficient than jet propulsion, some of the reduction in energy usage relative to other cephalopods may result from the use of fins as the primary means of propulsion. V. infernalis undergoes a rapid metamorphosis which consists of changes in the position, size and shape of the fins. This suggests that there are changes in the selective factors affecting locomotion through ontogeny. The present study describes these changes in relation to models for underwater ‘flight’. Citrate synthase (CS) and octopine dehydrogenase (ODH) activities, indicative of aerobic and anaerobic metabolism, respectively, were measured in fin, mantle and arm tissue across a range of body size of four orders of magnitude. The low enzymatic activities in both posterior and anterior fin tissue and the relatively high activity in mantle muscle prior to metamorphosis indicate that jet propulsion using mantle contraction is the primary means of propulsion in juvenile V. infernalis. The increase in CS activity with size after metamorphosis suggests an increased use of the fins for lift-based propulsion. Fin swimming appears to be the primary means of propulsion at all adult sizes. The negative allometry of CS activity in mantle and arm muscle is consistent with the scaling of oxygen consumption previously measured for V. infernalis and with the scaling of aerobic metabolism observed in most animals. The unusual positive allometry of fin muscle CS activity suggests that the use of fins is either relatively more important or more costly in larger animals. Positive scaling of ODH activity in all tissues suggests that fin propulsion, jet propulsion and medusoid ‘bell-swimming’ are all important for burst escape responses. Enzyme activities in Cirrothauma murrayi are consistent with finswimming observed from submersibles, while those in Opisthoteuthis californiana suggest a strong reliance on medusoid swimming using the arms. The transition from jet propulsion to paired-fin ‘flight’ with increasing body size in Vampyroteuthis infernalis appears functionally to be an ontogenetic ‘gait-transition’

    Staying for the benefits:Location‐specific insider advantages for geographically immobile students in higher education

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    In the youth mobility research, young people's geographical immobility is often associated with negative connotations. This paper challenges this discourse by analysing the location-specific insider advantages (LSIAs) of geographically immobile young adults in higher education institutions (HEI). We use data from a survey of students in two locations in Denmark: the peripheral city of Esbjerg and the metropolis of Copenhagen. We categorise students with diverse geographical mobility backgrounds into four (im)mobility types: ‘local stayers’, ‘regional commuters’, ‘regional in-movers’, and ‘distant in-movers’. The paper explores LSIAs across (im)mobility type and location type. We find that immobile students are more likely to have a connection to, and experience with, the local labour market, to be satisfied with their social life, and to live with their parents compared with their geographically mobile peers. However, the advantages differ in type and amount between the peripheral and the urban case locations. We conclude that immobility should be (re)framed as an advantageous strategy for some young adults in early higher education

    Monetary Policy, Regulation and Volatile Markets

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    Turmoil in financial markets causes reflection. Is monetary policy conducted in the most efficient way? Are regulatory and supervisory arrangements adequate when market volatility increases and financial institutions come under stress? In the present SUERF Study, we have collected the reflections by an outstanding group of top officials, researchers and observers. The editors are proud to be able to present their joint insights to SUERF readers. The papers were presented at the 27th SUERF Colloquium in Munich in June 2008: New trends in asset management: Exploring the implications.Financial markets, volatility, regulatory and supervisory arrangements, LATW, bubbles, monetary policy, asset prices, interest rate policy, LTCM, Basel II, MiFID, subprime, CDOs

    Monetary Policy, Regulation and Volatile Markets

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    Turmoil in financial markets causes reflection. Is monetary policy conducted in the most efficient way? Are regulatory and supervisory arrangements adequate when market volatility increases and financial institutions come under stress? In the present SUERF Study, we have collected the reflections by an outstanding group of top officials, researchers and observers. The editors are proud to be able to present their joint insights to SUERF readers. The papers were presented at the 27th SUERF Colloquium in Munich in June 2008: New trends in asset management: Exploring the implications

    Amphidromy Links a Newly Documented Fish Community of Continental Australian Streams, to Oceanic Islands of the West Pacific

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    BACKGROUND: Indo-Pacific high island streams experience extreme hydrological variation, and are characterised by freshwater fish species with an amphidromous life history. Amphidromy is a likely adaptation for colonisation of island streams following stochastic events that lead to local extirpation. In the Wet Tropics of north-eastern Australia, steep coastal mountain streams share similar physical characteristics to island systems. These streams are poorly surveyed, but may provide suitable habitat for amphidromous species. However, due to their ephemeral nature, common non-diadromous freshwater species of continental Australia are unlikely to persist. Consequently, we hypothesise that coastal Wet Tropics streams are faunally more similar, to distant Pacific island communities, than to nearby faunas of large continental rivers. METHODS/PRINCIPAL FINDINGS: Surveys of coastal Wet Tropics streams recorded 26 species, 10 of which are first records for Australia, with three species undescribed. This fish community is unique in an Australian context in that it contains mostly amphidromous species, including sicydiine gobies of the genera Sicyopterus, Sicyopus, Smilosicyopus and Stiphodon. Species presence/absence data of coastal Wet Tropics streams were compared to both Wet Tropics river networks and Pacific island faunas. ANOSIM indicated the fish fauna of north-eastern Australian coastal streams were more similar to distant Pacific islands (R = 0.76), than to nearby continental rivers (R = 0.98). MAIN CONCLUSIONS/SIGNIFICANCE: Coastal Wet Tropics streams are faunally more similar to distant Pacific islands (79% of species shared), than to nearby continental fauna due to two factors. First, coastal Wet Tropics streams lack many non-diadromous freshwater fish which are common in nearby large rivers. Second, many amphidromous species found in coastal Wet Tropics streams and Indo-Pacific islands remain absent from large rivers of the Wet Tropics. The evolutionary and conservation significance of this newly discovered Australian fauna requires clarification in the context of the wider amphidromous fish community of the Pacific

    Relationship between fibroblastic foci profusion and high resolution CT morphology in fibrotic lung disease

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    Background Fibroblastic foci profusion on histopathology and severity of traction bronchiectasis on highresolution computed tomography (HRCT) have been shown to be predictors of mortality in patients with idiopathic pulmonary fibrosis (IPF). The aim of this study was to investigate the relationship between fibroblastic foci (FF) profusion and HRCT patterns in patients with a histopathologic diagnosis of usual interstitial pneumonia (UIP), fibrotic non-specific interstitial pneumonia (NSIP) and chronic hypersensitivity pneumonitis (CHP). Methods The HRCT scans of 162 patients with a histopathologic diagnosis of UIP or fibrotic NSIP (n = 162) were scored on extent of groundglass opacification, reticulation, honeycombing, emphysema and severity of traction bronchiectasis. For each patient, a fibroblastic foci profusion score based on histopathologic appearances was assigned. Relationships between extent of fibroblastic foci and individual HRCT patterns were investigated using univariate correlation analysis and multivariate linear regression. Results Increasing extent of reticulation (P < 0.0001) and increasing severity of traction bronchiectasis (P < 0.0001) were independently associated with increasing FF score within the entire cohort. Within individual multidisciplinary team diagnosis subgroups, the only significant independent association with FF score was severity of traction bronchiectasis in patients with idiopathic pulmonary fibrosis (IPF)/UIP (n = 66, r2 = 0.19, P < 0.0001) and patients with chronic hypersensitivity pneumonitis (CHP) (n = 49, r2 = 0.45, P < 0.0001). Furthermore, FF score had the strongest association with severity of traction bronchiectasis in patients with IPF (r2 = 0.34, P < 0.0001) and CHP (r2 = 0.35, P < 0.0001). There was no correlation between FF score and severity of traction bronchiectasis in patients with fibrotic NSIP. Global disease extent had the strongest association with severity of traction bronchiectasis in patients with fibrotic NSIP (r2 = 0.58, P < 0.0001). Conclusion In patients with fibrotic lung disease, profusion of fibroblastic foci is strikingly related to the severity of traction bronchiectasis, particularly in IPF and CHP. This may explain the growing evidence that traction bronchiectasis is a predictor of mortality in several fibrotic lung diseases

    Evidence-Based Interventions and Strategies for the Grand Challenges Approach: The Need for Judgement

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    What is the value of evidence-based interventions in addressing “Grand Challenges”? Building upon the EPOS Grand Challenges work (Sakhrani et al., 2017), this paper explores whether evidence-based approaches developed for management and policy are relevant to addressing Grand Challenges. It discusses the criticisms of the Evidence-based Management approach and argues that evidence is a necessary, but not sufficient input in the decisionmaking process of addressing Grand Challenges

    Applications of Film Tomography Technique for QNDE

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    Tomography with X- and gamma- rays provides three-dimensional radiographic information on the examined object. The film-based tomography (1,2) generates a summation-image of a surface within the object by continuously combining back projections directly on the film. This method has many attractive features for industrial applications in which cost and simplicity are of primary importance. Some of the features are: (1) The absence of post processing allows this method to yield an image immediately on development of the film.; (2) Conventional radiologists need a short training time to master the technique as most components and concepts are familiar to them: e. g. radiation sources, films, screens, collimators, filters, processing units, viewers, exposure, contrast, resolution.; (3) Purpose oriented system optimized for a certain range of products, may be built with costs much less than digital computing trans-axial tomography (CT).; (4) Tomographic images of surfaces of critical areas within the examined object are directly recorded on films curved to match the required shape.; (5) Tomographs on film may be digitized and imaged-processed by commercial system developed for conventional radiographs.; (6) The slice thickness of the recorded surface may be in the order of magnitude of the thickness of the film-emulsion.; (7) The quality of the tomograph is high especially for high- contrast objects (2) and whenever the noise and the dynamic-range of the film do not impose a limitation on the information to be extracted.</p

    Influence of fractional flow reserve on grafts patency. Systematic review and patient-level meta-analysis

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    Objective: To investigate the impact of invasive functional guidance for coronary artery bypass graft surgery (CABG) on graft failure. Background: Data on the impact of fractional flow reserve (FFR) in guiding CABG are still limited. Methods: Systematic review and individual patient data meta-analysis were performed. Primary objective was the risk of graft failure, stratified by FFR. Risk estimates are reported as odds ratios (ORs) derived from the aggregated data using random-effects models. Individual patient data were analyzed using mixed effect model to assess relationship between FFR and graft failure. This meta-analysis is registered in PROSPERO (CRD42020180444). Results: Four prospective studies comprising 503 patients referred for CABG, with 1471 coronaries, assessed by FFR were included. Graft status was available for 1039 conduits at median of 12.0 [IQR 6.6; 12.0] months. Risk of graft failure was higher in vessels with preserved FFR (OR 5.74, 95% CI 1.71–19.29). Every 0.10 FFR units decrease in the coronaries was associated with 56% risk reduction of graft failure (OR 0.44, 95% CI 0.34 to 0.59). FFR cut-off to predict graft failure was 0.79. Conclusion: Surgical grafting of coronaries with functionally nonsignificant stenoses was associated with higher risk of graft failure

    Influence of fractional flow reserve on grafts patency: Systematic review and patient-level meta-analysis.

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    To investigate the impact of invasive functional guidance for coronary artery bypass graft surgery (CABG) on graft failure. Data on the impact of fractional flow reserve (FFR) in guiding CABG are still limited. Systematic review and individual patient data meta-analysis were performed. Primary objective was the risk of graft failure, stratified by FFR. Risk estimates are reported as odds ratios (ORs) derived from the aggregated data using random-effects models. Individual patient data were analyzed using mixed effect model to assess relationship between FFR and graft failure. This meta-analysis is registered in PROSPERO (CRD42020180444). Four prospective studies comprising 503 patients referred for CABG, with 1471 coronaries, assessed by FFR were included. Graft status was available for 1039 conduits at median of 12.0 [IQR 6.6; 12.0] months. Risk of graft failure was higher in vessels with preserved FFR (OR 5.74, 95% CI 1.71-19.29). Every 0.10 FFR units decrease in the coronaries was associated with 56% risk reduction of graft failure (OR 0.44, 95% CI 0.34 to 0.59). FFR cut-off to predict graft failure was 0.79. Surgical grafting of coronaries with functionally nonsignificant stenoses was associated with higher risk of graft failure
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