205 research outputs found

    Mesozooplankton size structure in the Canary Current System

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    Changes in plankton composition influences the dynamics of marine food webs and carbon sinking rates. Understanding the core structure and function of the plankton distribution is of paramount importance to know their role in trophic transfer and efficiency. Here, we studied the zooplankton distribution, abundance, composition, and size spectra for the characterization of the community under different oceanographic conditions in the Canaries-African Transition Zone (C-ATZ). This region is a transition zone between the coastal upwelling and the open ocean showing a high variability because of the physical, chemical, and biological changes between eutrophic and oligotrophic conditions through the annual cycle. During the late winter bloom (LWB), chlorophyll a and primary production were higher compared to that of the stratified season (SS), especially in the upwelling influenced area. Abundance distribution analysis clustered stations into two main groups according to the season (productive versus stratified season), and one group sampled in the upwelling influenced area. Size-spectra analysis showed steeper slopes during daytime in the SS, suggesting a less structured community and a higher trophic efficiency during the LWB due to the favorable oceanographic conditions. We also observed a significant difference between day and nighttime size spectra due to community change during diel vertical migration. Cladocera were the key taxa differentiating an Upwelling-group, from a LWB- and SS-group. These two latter groups were differentiated by Salpidae and Appendicularia mainly. Data obtained in this study suggested that abundance composition might be useful when describing community taxonomic changes, while size-spectra gives an idea of the ecosystem structure, predatory interactions with higher trophic levels and shifts in size structure

    Delimiting Cryptic Morphological Variation among Human Malaria Vector Species using Convolutional Neural Networks

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    Deep learning is a powerful approach for distinguishing classes of images, and there is a growing interest in applying these methods to delimit species, particularly in the identification of mosquito vectors. Visual identification of mosquito species is the foundation of mosquito-borne disease surveillance and management, but can be hindered by cryptic morphological variation in mosquito vector species complexes such as the malaria-transmitting Anopheles gambiaecomplex. We sought to apply Convolutional Neural Networks (CNNs) to images of mosquitoes as a proof-of-concept to determine the feasibility of automatic classification of mosquito sex, genus, species, and strains using whole-body, 2D images of mosquitoes. We introduce a library of 1, 709 images of adult mosquitoes collected from 16 colonies of mosquito vector species and strains originating from five geographic regions, with 4 cryptic species not readily distinguishable morphologically even by trained medical entomologists. We present a methodology for image processing, data augmentation, and training and validation of a CNN. Our best CNN configuration achieved high prediction accuracies of 96.96% for species identification and 98.48% for sex. Our results demonstrate that CNNs can delimit species with cryptic morphological variation, 2 strains of a single species, and specimens from a single colony stored using two different methods. We present visualizations of the CNN feature space and predictions for interpretation of our results, and we further discuss applications of our findings for future applications in malaria mosquito surveillance

    Non-volatile tuning of normally-on and off states of deep depletion ZrO2/O-terminated high voltage diamond MOSFET

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    Based on the stability of the deep depletion regime in diamond and the outstanding properties of this promising material for its use in power devices, p-channel deep depletion metal oxide semiconductor field effect transistors were fabricated on a (001) Ib nitrogen-doped high pressure high temperature diamond substrate. Taking advantage of the new concept of the non-volatile diamond-based photo switch, it is demonstrated that it is possible to tune the normally-on and normally-off states of the transistor by configuring the pn-junction space charge region. The devices under study was designed following an interdigital-like and a circular-like architectures presenting low threshold voltages (between 3 V and −3 V), an on/off ratio of 107 and a critical electric field numerically assessed of 9 MV.cm−1 at room temperature. This new degree of freedom opens the route for diamond based power electronics.8 página

    Swimbladder properties of Cyclothone spp. in the northeast Atlantic Ocean and the Western Mediterranean Sea

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    Non-migratory bristlemouth fishes (Cyclothone spp.) are the most abundant vertebrates on Earth and play an important role in the biological carbon pump by remineralizing organic carbon in deep ecosystems. Acoustic data and net sampling are often used in combination to estimate fish and zooplankton biomass, but this procedure may be subject to several sources of error when applied to mesopelagic species. For instance, the allocation of echoes to species has often been biased by not considering Cyclothone spp. due to the use of nets targeting larger fish. Furthermore, the acoustic properties of the target organisms must be well understood to convert acoustic density into numerical density. The characteristics of a fish’s swimbladder are the most relevant features necessary to assess its acoustic properties. This study provides information on the swimbladder properties of six Cyclothone species inhabiting the meso- and bathypelagic layers in the North Atlantic Ocean and Mediterranean Sea, including swimbladder location within the body, fat tissue content, morphology, morphometry (only available for C. braueri and C. pseudopallida), and fish body-mass density (only available for C. braueri, C. pseudopallida, C. pallida, and C. pygmaea). The studied species showed a functional physoclistous swimbladder, with well-developed gas glands and rete mirabile and numerous capillaries in the case of the shallower species C. braueri and C. pseudopallida (mainly distributed from 400 to 600 m depth), and a fat-invested swimbladder in species with deeper vertical distribution (C. livida, C. microdon, C. pallida, and C. pygmaea). The fat content in the swimbladder (C. pallida and C. microdon) increased with depth and latitude, reducing the space in the swimbladder that could contain gas. Changes in swimbladder size and volume during growth were analyzed for shallower species, where swimbladder volume and equivalent radius followed negative allometric growth in relation to body length. Finally, values of body-mass density (ρ) and gas content required for neutral buoyancy (VG) were estimated for C. braueri and C. pygmaea collected between 350 and 550 m (ρ = 1.052–1.072 g·cm−3, VG = 2%–4%; ρ = 1.052–1.062 g·cm−3, VG = 3.6%), and for C. pallida and C. pseudopallida sampled in the 450–700 m layer (ρ = 1.052–1.062 g·cm−3, VG = 2.6–3.1%; ρ = 1.052–1.062 g·cm−3, VG = 2.8%–3.25%). Results in this study highlight the change in scattering behavior of Cyclothone species from gas-bearing organisms (those that contain gas in their swimbladder) in the upper mesopelagic zone to the fluid-like scattering (with fat-filled swimbladders) of the deeper and northern individuals. The data presented in this manuscript are important for parametrizing acoustic backscattering models built to estimate the echo of Cyclothone species, although further work is needed, particularly for individuals with partially invested swimbladders with an irregular fat-free shape

    Building a transitional care checklist in rheumatology: A Delphi-like survey.

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    To design a transitional care checklist to be used by and facilitate the work of health professionals in providing transitional care for children with a chronic rheumatologic disease and their families. A Delphi-like study among an international expert panel was carried out in four steps: (1) a working group of 6 specialists established a draft; (2) a web-survey among a panel of international experts evaluated it; (3) a 2-day consensus conference with an expert panel discussed items not reaching agreement; (4) a web-survey among the panel of international experts with the list of reformulated items. The first draft of the checklist included 38 items in 3 phases of transition and 5 age groups. Thirty-three international experts evaluated the checklist reaching≥80% agreement for 26 items and ≤80% for 12. The consensus conference of 12 experts discussed and redefined the 12 items. Twenty-five international experts filled out the web-survey and all items reached a minimum of 80% agreement except one. The final checklist was reached. This Delphi-like study defined what themes should be included and at what age they need to be addressed with patients with a chronic rheumatology disease and their families during transition. This checklist reached a strong international and interdisciplinary consensus while examining transition in a broad way. It should now be spread widely to health professionals to be used by all those who care for adolescents aged≥12 years at times of transition. It could be transposed to most chronic conditions. Recommendations for further research are given

    In Situ Observations of the Deformation Behavior and Fracture Mechanisms of Ti-45Al-2Nb-2Mn+0.8 vol pct TiB₂

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    The deformation and fracture mechanisms of a nearly lamellar Ti-45Al-2Nb-2Mn (at. pct) + 0.8 vol pct TiB₂ intermetallic, processed into an actual low-pressure turbine blade, were examined by means of in situ tensile and tensile-creep experiments performed inside a scanning electron microscope (SEM). Low elongation-to-failure and brittle fracture were observed at room temperature, while the larger elongations-to-failure at high temperature facilitated the observation of the onset and propagation of damage. It was found that the dominant damage mechanisms at high temperature depended on the applied stress level. Interlamellar cracking was observed only above 390 MPa, which suggests that there is a threshold below which this mechanism is inhibited. Failure during creep tests at 250 MPa was controlled by intercolony cracking. The in situ observations demonstrated that the colony boundaries are damage nucleation and propagation sites during tensile creep, and they seem to be the weakest link in the microstructure for the tertiary creep stage. Therefore, it is proposed that interlamellar areas are critical zones for fracture at higher stresses, whereas lower stress, high-temperature creep conditions lead to intercolony cracking and fracture.The authors are grateful to Industria de Turbo Propulsores, S.A. for supplying the intermetallic blades. Funding from the Spanish Ministry of Science and Innovation through projects MAT2009-14547-C02-01 and MAT2009-14547-C02-02 is acknowledged. The Madrid Regional Government supported this project partially through the ESTRUMAT grant P2009/MAT-1585. C.J.B. acknowledges the support from Grant SAB2009-0045 from the Spanish Ministry of Education for his sabbatical stage in Madrid.Publicad

    Dynamics of serum antibodies to and load of porcine circovirus type 2 (PCV2) in pigs in three finishing herds, affected or not by postweaning multisystemic wasting syndrome

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    Background: Despite that PMWS commonly affects pigs aged eight to sixteen weeks; most studies of PMWS have been conducted during the period before transfer to finishing herds. This study focused on PCV2 load and antibody dynamics in finishing herds with different PMWS status. Methods: Sequentially collected blood samples from 40 pigs in each of two Swedish (A and B) and one Norwegian (C) finishing herds were analysed for serum PCV2-load and -antibodies and saliva cortisol. The two Swedish herds differed in PMWS status, despite receiving animals from the same sow pool (multi-site production). However, the PMWS-deemed herd (A) had previously also received pigs from the spot market. ResultsThe initial serum PCV2 load was similar in the two Swedish herds. In herd A, it peaked after two weeks in the finishing herd and a high number of the pigs had serum PCV2 levels above 10(7) per ml. The antibody titres increased continually with exception for the pigs that developed PMWS, that had initially low and then declining antibody levels. Pigs in the healthy herd B also expressed high titres of antibodies to PCV2 on arrival but remained at that level throughout the study whereas the viral load steadily decreased. No PCV2 antibodies and only low amounts of PCV2 DNA were detected in serum collected during the first five weeks in the PMWS-free herd C. Thereafter a peak in serum PCV2 load accompanied by an antibody response was recorded. PCV2 from the two Swedish herds grouped into genotype PCV2b whereas the Norwegian isolate grouped into PCV2a. Cortisol levels were lower in herd C than in herds A and B. Conclusions: The most obvious difference between the Swedish finishing herds and the Norwegian herd was the time of infection with PCV2 in relation to the time of allocation, as well as the genotype of PCV2. Clinical PMWS was preceded by low levels of serum antibodies and a high load of PCV2 but did not develop in all such animals. It is notable that herd A became affected by PMWS after errors in management routine, emphasising the importance of proper hygiene and general disease-preventing measures
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