257 research outputs found

    Acoustic and visual stimuli combined promote stronger responses to aerial predation in fish

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    Bird predation poses a strong selection pressure on fish. Since birds must enter the water to catch fish, a combination of visual and mechano-acoustic cues (multimodal) characterize an immediate attack, while single cues (unimodal) may represent less dangerous disturbances. We investigated whether fish could use this information to distinguish between non-threatening and dangerous events and adjust their antipredator response to the perceived level of risk. To do so, we investigated the antipredator behavior of the sulphur molly (Poecilia sulphuraria), a small freshwater fish which is almost exclusively preyed on by piscivorous birds in its endemic sulfide spring habitat. In a field survey, we confirmed that these fish frequently have to distinguish between disturbances stemming from attacking birds (multimodal) and those which pose no (immediate) threat such as bird overflights (unimodal). In a laboratory experiment, we then exposed fish to artificial visual and/or acoustic stimuli presented separately or combined. Sensitivity was high regardless of stimulus type and number (more than 96% of fish initiated diving), but fish dove deeper, faster, and for longer when both stimuli were available simultaneously. Based on the system’s high rates of bird activity, we argue that such an unselective dive initiation with subsequent fine-tuning of diving parameters in accordance to cue modality represents an optimal strategy for these fish to save energy necessary to respond to future attacks. Ultimately, our study shows that fish anticipate the imminent risk posed by disturbances linked to bird predation through integrating information from both visual and acoustic cues.Peer Reviewe

    Modelizacion numerica de cargas de viento sobre un tanque de almacenamiento de combustible

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    National audienceOne of the structural problems detected on oil storage tanks is wind-induced buckling failure. Accurate estimation of wind loads is important for the evaluation of structural integrity of these facilities. In this context, a numerical study is presented, employing the Reynolds Averaging Navier Stokes (RANS) methodology for the prediction of wind-induced pressure loads over a cylindrical storage tank. Mean pressure distributions obtained through RANS turbulence models, are compared with atmospheric boundary layer wind tunnel experimental measurements for a tank with both closed planar and conical roof shapes. Different aspect ratios and Reynolds numbers representative of the conditions present in oil storage tanks exposed to the atmosphere are considered. Details regarding both the employed numerical methodology and the computer implementation are discussed and presented. Finally, the conclusions obtained based on the present numerical study are introduced.Uno de los problemas estructurales detectados en tanques de almacenamiento de combustible es la falla por pandeo debido a cargas de viento. La adecuada estimación de estas cargas es importante para la evaluación de la integridad estructural de los mismos. En este contexto, se presenta un estudio numérico empleando la metodología Reynolds Averaging Navier Stokes (RANS) para la predicción de cargas de presión producida por el flujo de viento atmosférico sobre un tanque de almacenamiento ci-líndrico. Distribuciones de presión media obtenidas empleando distintos modelos de turbulencia RANS, son comparadas con las mediciones relevadas en un túnel de viento de capa límite atmosférica para un tanque con techo cerrado de forma plana y techo cónico de 25 grados. Diferentes relaciones de aspecto y números de Reynolds representativos de las condiciones presentes en tanques de almacenamiento de combustible expuestos a la atmósfera son considerados. Detalles sobre la metodología numérica em-pleada y aspectos de la implementación computacional son discutidos y presentados. Finalmente, se introducen las conclusiones obtenidas a partir del presente análisis numérico

    Diurnal Changes in Hypoxia Shape Predator-Prey Interaction in a Bird-Fish System

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    Animals often face changing environments, and behavioral flexibility allows them to rapidly and adaptively respond to abiotic factors that vary more or less regularly. However, abiotic factors that affect prey species do not necessarily affect their predators. Still, the prey’s response might affect the predator indirectly, yet evidence from the wild for such a classical bottom-up effect of abiotic factors shaping several trophic levels remains sparse. In many aquatic environments, daily changes in oxygen concentrations occur frequently. When oxygen levels drop to hypoxic levels, many fishes respond with aquatic surface respiration (ASR), during which they obtain oxygen by skimming the upper, oxygenated surface layer. By increasing time at the surface, fish become more vulnerable to fish-eating birds. We explored these cascading effects in a sulfidic spring system that harbors the endemic sulphur molly (Poecilia sulphuraria) as prey species and several fish-eating bird species. Sulfide-rich springs pose harsh conditions as hydrogen sulfide (H2S) is lethal to most metazoans and reduces dissolved oxygen (DO). Field sampling during three daytimes indicated that water temperatures rose from morning to (after)noon, resulting in the already low DO levels to decrease further, while H2S levels showed no diurnal changes. The drop in DO levels was associated with a decrease in time spent diving in sulphur mollies, which corresponded with an increase in ASR. Interestingly, the laboratory-estimated threshold at which the majority of sulphur mollies initiate ASR (ASR50: <1.7 mg/L DO) was independent of temperature and this value was exceeded daily when hypoxic stress became more severe toward noon. As fish performed ASR, large aggregations built up at the water surface over the course of the day. As a possible consequence of fish spending more time at the surface, we found high activity levels of fish-eating birds at noon and in the afternoon. Our study reveals that daily fluctuations in water’s oxygen levels have the potential to alter predator-prey interactions profoundly and thus highlights the joined actions of abiotic and biotic factors shaping the evolution of a prey species.Peer Reviewe

    Compositional and functional stability of aerobic methane consuming communities in drained and rewetted peat meadows

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    The restoration of peatlands is an important strategy to counteract subsidence and loss of biodiversity. However, responses of important microbial soil processes are poorly understood. We assessed functioning, diversity and spatial organization of methanotrophic communities in drained and rewetted peat meadows with different water table management and agricultural practice. Results show that the methanotrophic diversity was similar between drained and rewetted sites with a remarkable dominance of the genus Methylocystis. Enzyme kinetics depicted no major differences, indicating flexibility in the methane (CH4) concentrations that can be used by the methanotrophic community. Short-term flooding led to temporary elevated CH4 emission but to neither major changes in abundances of methane-oxidizing bacteria (MOB) nor major changes in CH4 consumption kinetics in drained agriculturally used peat meadows. Radiolabeling and autoradiographic imaging of intact soil cores revealed a markedly different spatial arrangement of the CH4 consuming zone in cores exposed to near-atmospheric and elevated CH4. The observed spatial patterns of CH4 consumption in drained peat meadows with and without short-term flooding highlighted the spatial complexity and responsiveness of the CH4 consuming zone upon environmental change. The methanotrophic microbial community is not generally altered and harbors MOB that can cover a large range of CH4 concentrations offered due to water-table fluctuations, effectively mitigating CH4 emission

    PHENOquad: A new multi sensor platform for field phenotyping and screening of yield relevant characteristics within grapevine breeding research

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    Balanced and stable yield is a major trait in grapevine breeding and breeding research. Grapevine yield hereby is a complex quantitative trait, as it is influenced by multiple plant parameters, like berry size, number of berries per bunch, number of bunches per shoot, management, and environmental factors. In the current breeding process, the complexity of this trait has shown that a classification according to descriptive factors for marker development is only possible to a limited extent. Precise field phenotyping of yield-related traits is the basic prerequisite to be able to measure such quantitative traits. This, however, is the major bottleneck due to labor, time and constrains of plant material in the breeding process. For this reason, one of our main goals with the newly developed phenotyping platform PHENOquad with its multisensor system PHENOboxx is to improve phenotyping efficiency of grapevine yield to overcome the phenotyping bottleneck. The newly developed embedded vision system PHENOboxx is mounted on an "all-terrain vehicle (ATV)". This allows a fast data acquisition on a large number of individual vines. In order to evaluate the yield potential of breeding material in comparison to established grapevine cultivars, various yield-related parameters of the vines are quantified directly in the field with high spatial and temporal resolution. As key parameters for yield-related phenotyping, the number of shoots, bunches, berries and the weight of dormant pruning wood was identified. The image data acquired are annotated to train the artificial intelligence (AI). Within the process, the image analysis results are compared to annotated ground truth data and correlated with the field reference data. We expect to increase the precision, target specificity and throughput of screening grapevine material without reducing its accuracy over time by using the PHENOquad. In addition, a weighting of yield-relevant parameters would be possible. This opens up new possibilities for efficient plant evaluation in the scope of grapevine breeding. Also new application possibilities for precision viticulture are conceivable

    Ten simple rules for making training materials FAIR

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    Author summary: Everything we do today is becoming more and more reliant on the use of computers. The field of biology is no exception; but most biologists receive little or no formal preparation for the increasingly computational aspects of their discipline. In consequence, informal training courses are often needed to plug the gaps; and the demand for such training is growing worldwide. To meet this demand, some training programs are being expanded, and new ones are being developed. Key to both scenarios is the creation of new course materials. Rather than starting from scratch, however, it’s sometimes possible to repurpose materials that already exist. Yet finding suitable materials online can be difficult: They’re often widely scattered across the internet or hidden in their home institutions, with no systematic way to find them. This is a common problem for all digital objects. The scientific community has attempted to address this issue by developing a set of rules (which have been called the Findable, Accessible, Interoperable and Reusable [FAIR] principles) to make such objects more findable and reusable. Here, we show how to apply these rules to help make training materials easier to find, (re)use, and adapt, for the benefit of all

    2000 Ohio-Grape Wine Short Course

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    Air, water, sun, and fire--the cooper's footprint on the barrel / Henry Work -- Keeping the bugs unhappy; successful barrel sanitation and maintenance / Henry Work -- Recommended methods for cleaning and maintaining oak cooperage / Phil Burton and Henry Work, with Jim Yerkes -- Chip me, stave me, oak me! The romance, dollars and sense of barrel alternatives / Tim DiPlacido -- Oak experiments / Roland Riesen -- Barrel experiment / Nick Ferrante -- Exploring the versatility and potential of vidal / Roland Riesen -- Ferrante: 1999 vineyard planting / Nick Ferrante -- Breeding rootstocks for current and impending viticultural problems / Andrew Walker -- Grape expectations looking toward traditional and non-traditional sponsors to enhance your event / Doniella Winchell -- Assessing grape maturity by taste and by numbers / Thomas Henick-Kling -- Influence of fruit condition on wine quality / James F. Gallander -- Influence of post bottling storage temperature and SO2 on wine quality / T. E. Steiner -- What we do at harvest to help wine quality / Tony Debevc -- Delivering wine quality / Nick Ferrante -- Criteria for selecting rootstocks / Andrew Walker -- A comparison of Pinot noir production in New York and Burgundy / Pascal Durand and Leslie Weston -- A unique approach to harvest labor / Fran Massaro -- New fungicide registrations for grapes in the year 2000 / Michael Ellis -- Studies to determine time of susceptibility of grape berry and rachis tissues to infection by Phomopsis viticola / O. Erincik, L. V. Madden, D. C. Ferree and M. A. Ellis -- Rootstock performance in Ohio / Arnie Esterer -- Growing your own: vinifera grafting experiments (1999) / Ron Barrett -- Developing an effective fungicide spray program for wine grapes in Ohio / Michael Ellis -- Light and fruit set / David C. Ferree, David M. Scurlock and John C. Schmid -- Soil amendments and mulches in tree health management / Harry Hoitink, Matthew Krause and Randy Zondag -- Report of 5th International Symposium on Cool Climate Viticulture and Enology / Roland Riesen -- Control strategies for soil insects in the vineyard / Roger Williams and Dan Fickl

    Green synthesis of antimicrobial silver nanoparticles using aqueous leaf extracts from three Congolese plant species (Brillantaisia patula, Crossopteryx febrifuga and Senna siamea)

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    In the present study, silver nanoparticles (AgNPs) were synthesized using aqueous leaf extracts of three Congolese plant species, namely Brillantaisia patula (BR-PA), Crossopteryx febrifuga (CR-FE) and Senna siamea (SE-SI). The obtained AgNPs were studied for their optical, structural, surface morphological and antibacterial properties. The prepared AgNPs were characterized by using UV-Visible spectra, Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray spectroscopy (EDX) and X-ray diffractometer (XRD). The synthesized nanoparticles were spherical shaped and well-dispersed with average sizes ranging from 45 to 110 nm. The AgNPs derived from BR-PA, CR-FE and SE-SI exhibited higher antibacterial activity against three bacterial pathogens of the human skin compared to their respective crude extracts and AgNO3. This indicated that the biomolecules covering the nanoparticles may enhance the biological activity of metal nanoparticles. Hence, our results support that biogenic synthesis of AgNPs from Congolese plants constitutes a potential area of interest for the therapeutic management of microbial diseases such as infectious skin diseases
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