536 research outputs found
A century of fish growth in relation to climate change, population dynamics and exploitation
Marine ecosystems, particularly in high‐latitude regions such as the Arctic, have been significantly affected by human activities and contributions to climate change. Evaluating how fish populations responded to past changes in their environment is helpful for evaluating their future patterns, but is often hindered by the lack of long‐term biological data available. Using otolith increments of Northeast Arctic cod (Gadus morhua) as a proxy for individual growth, we developed a century‐scale biochronology (1924–2014) based on the measurements of 3,894 fish, which revealed significant variations in cod growth over the last 91 years. We combined mixed‐effect modeling and path analysis to relate these growth variations to selected climate, population and fishing‐related factors. Cod growth was negatively related to cod population size and positively related to capelin population size, one of the most important prey items. This suggests that density‐dependent effects are the main source of growth variability due to competition for resources and cannibalism. Growth was also positively correlated with warming sea temperatures but negatively correlated with the Atlantic Multidecadal Oscillation, suggesting contrasting effects of climate warming at different spatial scales. Fishing pressure had a significant but weak negative direct impact on growth. Additionally, path analysis revealed that the selected growth factors were interrelated. Capelin biomass was positively related to sea temperature and negatively influenced by herring biomass, while cod biomass was mainly driven by fishing mortality. Together, these results give a better understanding of how multiple interacting factors have shaped cod growth throughout a century, both directly and indirectly.publishedVersio
Light field geometry of a standard plenoptic camera
The Standard Plenoptic Camera (SPC) is an innovation in photography, allowing for acquiring two-dimensional images focused at different depths, from a single exposure. Contrary to conventional cameras, the SPC consists of a micro lens array and a main lens projecting virtual lenses into object space. For the first time, the present research provides an approach to estimate the distance and depth of refocused images extracted from captures obtained by an SPC. Furthermore, estimates for the position and baseline of virtual lenses which correspond to an equivalent camera array are derived. On the basis of paraxial approximation, a ray tracing model employing linear equations has been developed and implemented using Matlab. The optics simulation tool Zemax is utilized for validation purposes. By designing a realistic SPC, experiments demonstrate that a predicted image refocusing distance at 3.5 m deviates by less than 11% from the simulation in Zemax, whereas baseline estimations indicate no significant difference. Applying the proposed methodology will enable an alternative to the traditional depth map acquisition by disparity analysis.European commisio
Risk factors for oesophageal squamous cell carcinoma in Mozambique
Studies evaluating risk factors for the occurrence of oesophageal squamous cell carcinoma (ESCC) in high-risk regions might contribute to a better understanding of the oesophageal cancer aetiology and incidence variation worldwide. We aimed to quantify the association between alcohol, tobacco and dietary history, and the occurrence of ESCC in Mozambique. A case–control study was conducted at Maputo Central Hospital. Cases (n = 143) were patients with newly diagnosed oesophageal cancer recruited in the Gastroenterology Service. Controls (n = 212) were selected in the Orthopaedic Ward among subjects with pathologies related to trauma. Crude and adjusted odds ratios (ORs), and the corresponding 95% confidence intervals (CI) were computed using non-conditional logistic regression. The risk of ESCC was higher in older participants and lower in those with higher household income. Alcohol drinking (lifetime consumption ≥ 55.1 versus 0 kg ethanol: OR = 5.56; 95% CI: 2.43–12.73) and tobacco smoking (lifetime consumption ≥ 20 versus 0 pack/years: OR=7.26; 95% CI: 1.42–37.17) were associated with increased risk of ESCC. Tea (at least twice daily versus less than daily: OR = 5.09; 95% CI: 2.45–10.58) was also associated with the occurrence of ESCC. No significant differences were observed for fruit and vegetable and for smoked meat or fish consumption. Findings from this study show that in our sample, the occurrence of ESCC is strongly influenced by lifetime consumption of tobacco and alcohol, and with tea drinking. This highlights the importance of preventive measures based on the promotion of healthier lifestyles. Copyright: © the authors; licensee ecancermedicalscience
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Anatomical localization of progenitor cells in human breast tissue reveals enrichment of uncommitted cells within immature lobules
Introduction: Lineage tracing studies in mice have revealed the localization and existence of lineage-restricted mammary epithelial progenitor cells that functionally contribute to expansive growth during puberty and differentiation during pregnancy. However, extensive anatomical differences between mouse and human mammary tissues preclude the direct translation of rodent findings to the human breast. Therefore, here we characterize the mammary progenitor cell hierarchy and identify the anatomic location of progenitor cells within human breast tissues. Methods: Mammary epithelial cells (MECs) were isolated from disease-free reduction mammoplasty tissues and assayed for stem/progenitor activity in vitro and in vivo. MECs were sorted and evaluated for growth on collagen and expression of lineages markers. Breast lobules were microdissected and individually characterized based on lineage markers and steroid receptor expression to identify the anatomic location of progenitor cells. Spanning-tree progression analysis of density-normalized events (SPADE) was used to identify the cellular hierarchy of MECs within lobules from high-dimensional cytometry data. Results: Integrating multiple assays for progenitor activity, we identified the presence of luminal alveolar and basal ductal progenitors. Further, we show that Type I lobules of the human breast were the least mature, demonstrating an unrestricted pattern of expression of luminal and basal lineage markers. Consistent with this, SPADE analysis revealed that immature lobules were enriched for basal progenitor cells, while mature lobules consisted of increased hierarchal complexity of cells within the luminal lineages. Conclusions: These results reveal underlying differences in the human breast epithelial hierarchy and suggest that with increasing glandular maturity, the epithelial hierarchy also becomes more complex. Electronic supplementary material The online version of this article (doi:10.1186/s13058-014-0453-3) contains supplementary material, which is available to authorized users
Adaptive mutation using statistics mechanism for genetic algorithms
Copyright @ 2004 Springer-Verla
On the statistical mechanics of prion diseases
We simulate a two-dimensional, lattice based, protein-level statistical
mechanical model for prion diseases (e.g., Mad Cow disease) with concommitant
prion protein misfolding and aggregation. Our simulations lead us to the
hypothesis that the observed broad incubation time distribution in
epidemiological data reflect fluctuation dominated growth seeded by a few
nanometer scale aggregates, while much narrower incubation time distributions
for innoculated lab animals arise from statistical self averaging. We model
`species barriers' to prion infection and assess a related treatment protocol.Comment: 5 Pages, 3 eps figures (submitted to Physical Review Letters
In Vitro and In Silico Analyses of New Cinnamid and Rosmarinic Acid-Derived Compounds Biosynthesized in Escherichia coli as Leishmania amazonensis Arginase Inhibitors
Arginase is a metalloenzyme that plays a central role in Leishmania infections. Previously, rosmarinic and caffeic acids were described as antileishmanial agents and as Leishmania amazonensis arginase inhibitors. Here, we describe the inhibition of arginase in L. amazonensis by rosmarinic acid analogs (1–7) and new caffeic acid-derived amides (8–10). Caffeic acid esters and amides were produced by means of an engineered synthesis in E. coli and tested against L. amazonensis arginase. New amides (8–10) were biosynthesized in E. coli cultured with 2 mM of different combinations of feeding substrates. The most potent arginase inhibitors showed Ki(s) ranging from 2 to 5.7 μM. Compounds 2–4 and 7 inhibited L. amazonensis arginase (L-ARG) through a noncompetitive mechanism whilst compound 9 showed a competitive inhibition. By applying an in silico protocol, we determined the binding mode of compound 9. The competitive inhibitor of L-ARG targeted the key residues within the binding site of the enzyme, establishing a metal coordination bond with the metal ions and a series of hydrophobic and polar contacts supporting its micromolar inhibition of L-ARG. These results highlight that dihydroxycinnamic-derived compounds can be used as the basis for developing new drugs using a powerful tool based on the biosynthesis of arginase inhibitors
The pacing stress test: Thallium-201 myocardial imaging after atrial pacing. Diagnostic value in detecting coronary artery disease compared with exercise testing
Many patients suspected of having coronary artery disease are unable to undergo adequate exercise testing. An alternate stress, pacing tachycardia, has been shown to produce electrocardiographic changes that are as sensitive and specific as those observed during exercise testing. To compare thallium-201 imaging after atrial pacing stress with thallium imaging after exercise stress, 22 patients undergoing cardiac catheterization were studied with both standard exercise thallium imaging and pacing thallium imaging.Positive ischemic electrocardiographic changes (> 1 mm ST segment depression) were noted in 11 of 16 patients with coronary artery disease during exercise, and in 15 of the 16 patients during atrial pacing. One of six patients with normal or trivial coronary artery disease had a positive electrocardiogram with each test. Exercise thallium imaging was positive in 13 of 16 patients with coronary artery disease compared with 15 of 16 patients during atrial pacing. Three of six patients without coronary artery disease had a positive scan with exercise testing, and two of these same patients developed a positive scan with atrial pacing. Of those patients with coronary artery disease and an abnormal scan, 85% showed redistribution with exercise testing compared with 87% during atrial pacing. Segment by segment comparison of thallium imaging after either atrial pacing or exercise showed that there was a good correlation of the location and severity of the thallium defects (r = 0.83, p = 0.0001, Spearman rank correlation).It is concluded that the location and presence of both fixed and transient thallium defects after atrial pacing are closely correlated with the findings after exercise testing. Thus, atrial pacing may be used as a stress for myocardial perfusion scintigraphy in patients unable to complete a satisfactory exercise test
Impaired left atrial mechanical function after cardioversion: Relation to the duration of atrial fibrillation
AbstractObjectives. We hypothesized that the time course of the recovery of atrial systolic function may be related to the duration of atrial fibrillation before cardioversion and sought to study noninvesively the recovery of left atrial mechanical function utilizing serial transthoracic Doppler studies.Background. Recovery of atrial mechanical function may be delayed for several weeks after successful cardioversion of atrial fibrillation to sinus rhythm.Methods. After successful cardioversion, 60 patients with atrial fibrillation of brief (≤2 week, 17 patients), moderate (>2 to 6 weeks, 22 patients) or prolonged (>6 weeks, 21 patients) duration were followed up with serial transmitral pulsed Doppler echocardiography immediately (60 patients) and at 24 h (45 patients), 1 week (41 patients), 1 month (31 patients) and >3 months (30 patients) after cardioversion.Results. Atrial mechanical function is greater immediately and at 24 h and 1 week after cardioversion in patients with “brief” compared with “prolonged” atrial fibrillation. In all groups, atrial mechanical function increases over time, ultimately achieving similar levels. Full recovery of atrial mechanical function, however, is achieved within 24 h in patients with brief atrial fibrillation, within 1 week in patients with moderate-duration atrial fibrillation and within 1 month in patients with prolonged atrial fibrillation.Conclusions. Recovery of left atrial mechanical function is related to the duration of atrial fibrillation before cardioversion. These findings have important implications for assessing the early hemodynamic benefit of successful cardioversion
Acoustic-visual release and temporalities on scene : the founding of a tradition by Banda Calypso.
O objetivo deste artigo ? discutir, a partir do DVD comemorativo dos 15 anos da Banda Calypso, a proposi??o da funda??o de uma tradi??o de m?sica popular pelo grupo paraense. Para isso, em um primeiro momento, retomaremos o conceito de ?descarga ac?stica? para entender a peculiaridade do discurso do grupo frente a tradi??es intelectuais j? estabelecidas. Em seguida, abordaremos os mecanismos visuais e sonoros acionados pela Calypso no desdobramento de matrizes temporais espec?ficas. Isso permitir? refletir como essas temporalidades s?o inscritas na textualidade do pr?prio DVD. Entendemos que o ?brega?, compreendido a partir de uma refer?ncia ? matriz melodram?tica, consegue urdir tempos aparentemente desconexos e se torna um eixo condutor da narrativa.The purpose of this paper is to discuss the proposal to found a tradition of popular music made by Banda Calpyso in its 15-year commemorative DVD. Therefore, we seek to resignify the concept of ?acoustic release ?in order to understand the peculiarities of the discourse engendered by this group, especially in the questioning of established academic traditions. Then, we analyze the visual and sound mechanisms triggered by Calypso to configure specific temporalities. Our proposition is that the ?brega?, understood as a reference to a melodramatic matrix, can manage to unite seemingly disconnected times and becomes a guiding axis of the narrative
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