606 research outputs found

    Energetic Extremes in Aquatic Locomotion by Coral Reef Fishes

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    Underwater locomotion is challenging due to the high friction and resistance imposed on a body moving through water and energy lost in the wake during undulatory propulsion. While aquatic organisms have evolved streamlined shapes to overcome such resistance, underwater locomotion has long been considered a costly exercise. Recent evidence for a range of swimming vertebrates, however, has suggested that flapping paired appendages around a rigid body may be an extremely efficient means of aquatic locomotion. Using intermittent flow-through respirometry, we found exceptional energetic performance in the Bluelined wrasse Stethojulis bandanensis, which maintains tuna-like optimum cruising speeds (up to 1 metre s(-1)) while using 40% less energy than expected for their body size. Displaying an exceptional aerobic scope (22-fold above resting), streamlined rigid-body posture, and wing-like fins that generate lift-based thrust, S. bandanensis literally flies underwater to efficiently maintain high optimum swimming speeds. Extreme energetic performance may be key to the colonization of highly variable environments, such as the wave-swept habitats where S. bandanensis and other wing-finned species tend to occur. Challenging preconceived notions of how best to power aquatic locomotion, biomimicry of such lift-based fin movements could yield dramatic reductions in the power needed to propel underwater vehicles at high speed.Funding was provided by the Australian Research Council (to CJF) and the Danish Agency for Science, Technology and Innovation (to JFS). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    Elucidating the genetic determinants of the archetypal complex disease hypertriglyceridemia

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    Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in Canada. Among non-traditional risk factors, plasma triglyceride (TG) concentration is re-emerging as a significant risk factor. Patients with hypertriglyceridemia (HTG) – an archetypal complex phenotype defined by fasting plasma TG concentration \u3e95th percentile – thus have significantly increased CVD risk, compounded by associated co-morbidities such as obesity, metabolic syndrome and type 2 diabetes. However, the molecular pathways contributing to HTG susceptibility are incompletely defined. A better understanding of the genetic determinants that underlie the phenotypic spectrum of plasma TG and HTG susceptibility is necessary to identify novel genes and pathways that could be targeted to effectively lower plasma TG and improve cardiovascular risk. Accordingly, we sought to characterize the genetic architecture of HTG susceptibility and phenotypic heterogeneity using several modern genomic technologies, including high-density microarray genotyping and high-throughput resequencing of candidate genes in HTG patients and healthy controls. We demonstrate that a broad allelic spectrum of common small effect variants and rare large effect variants is associated with HTG. Furthermore, we demonstrate that significant overlap exists between genes and variants that modulate plasma TG and increase HTG susceptibility. Taken together, we suggest that HTG susceptibility is the result of a genetic burden of TG-raising alleles in genes that modulate plasma TG concentration. These findings provide a breadth of novel targets for pharmaceutical development in hopes of reducing plasma TG concentration and improve cardiovascular risk in HTG patients

    ADVANZ: Establishing a Pan-African platform for neglected zoonotic disease control through a One Health approach

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    Advocacy for neglected zoonotic diseases (ADVANZ) is a One Health Neglected Zoonotic Diseases (NZDs) project, funded by the European Commission through its 7th framework programme. The initiative aims at persuading decision makers and empowering stakeholders at local, regional, and international levels towards a coordinated fight against NZDs. ADVANZ is establishing an African platform to share experiences in the prevention and control of NZDs. The platform will compile and package existing knowledge or data on NZDs and generate evidence-based algorithms for improving surveillance and control with the ultimate aim of eliminating and eradicating these diseases. The platform will serve as a forum for African and international stakeholders, as well as existing One Health and NZD networks and harness and consolidate their efforts in the control and prevention of NZDs. The platform had its first meeting in Johannesburg, South Africa in March 2013

    Sculptures in Concurrency

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    We give a formalization of Pratt's intuitive sculpting process for higher-dimensional automata (HDA). Based on this, we show that sculptures, Pratt's Chu spaces, and Johansen's ST-structures are in close correspondence. We also develop an algorithm to decide whether a HDA can be sculpted and use this to show that some natural acyclic HDA are not sculptures. We believe that our result shed new light on the intuitions behind sculpting as a method of modeling concurrent behavior, showing the precise reaches of its expressiveness. We also show that there are sculptures whose unfoldings cannot besculpted, and that sculptures are the same as Euclidean cubical complexes. This exposes a close connection between geometric and combinatorial models for concurrency which may be of use for both areas

    A Comparison of Clustering and Missing Data Methods for Health Sciences

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    In this paper, we compare and analyze clustering methods with missing data in health behavior research. In particular, we propose and analyze the use of compressive sensing\u27s matrix completion along with spectral clustering to cluster health related data. The empirical tests and real data results show that these methods can outperform standard methods like LPA and FIML, in terms of lower misclassification rates in clustering and better matrix completion performance in missing data problems. According to our examination, a possible explanation of these improvements is that spectral clustering takes advantage of high data dimension and compressive sensing methods utilize the near-to-low-rank property of health data

    Colonization of the Philippines: An Analysis of U.S. Justificatory Rhetoric

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    The term “Filipino” offers more than a call to nationality; it also recalls the genesis of colonization in the Philippines. This thesis explores the colonial interventions of the United States in the Philippines at the turn of the 20th century, homing in on the Filipino education system as the United States’ primary method of colonizing the Filipino mind. Drawing from texts by Senator Alfred Beveridge, President William McKinley, the Philippine Commission, David Barrows, and Dr. Trinidad Pardo de Tavera, I offer an ideological criticism that demonstrates a cyclical nature between both justificatory rhetoric and ideology. Working with “ideological clusters,” this thesis demonstrates how justificatory discourse was used to mobilize American colonialism, yielding both symbolic and material consequences for the Filipino people

    Connections Between Local and Global Turbulence in Accretion Disks

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    We analyze a suite of global magnetohydrodynamic (MHD) accretion disk simulations in order to determine whether scaling laws for turbulence driven by the magnetorotational instability, discovered via local shearing box studies, are globally robust. The simulations model geometrically-thin disks with zero net magnetic flux and no explicit resistivity or viscosity. We show that the local Maxwell stress is correlated with the self-generated local vertical magnetic field in a manner that is similar to that found in local simulations. Moreover, local patches of vertical field are strong enough to stimulate and control the strength of angular momentum transport across much of the disk. We demonstrate the importance of magnetic linkages (through the low-density corona) between different regions of the disk in determining the local field, and suggest a new convergence requirement for global simulations -- the vertical extent of the corona must be fully captured and resolved. Finally, we examine the temporal convergence of the average stress, and show that an initial long-term secular drift in the local flux-stress relation dies away on a time scale that is consistent with turbulent mixing of the initial magnetic field.Comment: 8 Pages, 7 Figures ApJ, In Pres

    The skin mucosal barrier of lumpfish (Cyclopterus lumpus L.) is weakened by exposure to potential aquaculture production related stressors

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    Various cleaner fish species, such as the lumpfish (Cyclopterus lumpus L.), are used in the sea cage production of Atlantic salmon (Salmo salar L.) as a control measure against the ectoparasitic salmon louse (Lepeophtheirus salmonis). However, during severe lice infestation, alternative treatments are required to control parasitic burden. The aim of this study was to gain insight into how lumpfish skin responds to different chemicals used to treat parasites. We collected skin from lumpfish from both research facilities (tank reared fish) and commercial production (cage reared fish), and used operational welfare indicators (OWIs), in vitro models, histology and transcriptomics to study how the skin responded to two anti-parasitic oxidative chemicals, hydrogen peroxide (H2O2) and peracetic acid (PAA). Lumpfish sampled from the farm were classified as clinically healthy or weak according to their morbidity status, and fish from each category were used to gain insight into how the therapeutics affect the skin barrier. Differences between healthy and weakened (moribund) fish, and between treated fish from each of the two groups, were observed. Histological examination showed an overall reduced skin quality in fish characterized as moribund, including different grades of exposed bony plates. In vitro oxidant-treated lumpfish skin had reduced migration capacity of keratocytes, a weakened epidermal barrier and altered gene transcription, changes that are known predisposing factors to secondary infections. Skin from non-treated, healthy fish sampled from commercial farms exhibited similar features and attributes to oxidant-exposed tank reared fish from a research facility, suggesting that apparently healthy cage-held lumpfish exhibited stress responses in the epidermal barrier. The results of the study outline the risks and consequences lumpfish can face if accidentally subjected to potential anti-parasitic oxidant treatments aimed at Atlantic salmon. It also strengthens the evidence behind the requirement that lumpfish should be removed from the cages before being potentially exposed to this type of treatment and outlines the potential risks of differing husbandry practices upon lumpfish health, welfare and resilience.The skin mucosal barrier of lumpfish (Cyclopterus lumpus L.) is weakened by exposure to potential aquaculture production related stressorspublishedVersio
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