1,429 research outputs found

    Rotary solenoid shutter drive assembly and rotary inertia damper and stop plate assembly

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    A camera shutter assembly composed of a pair of superposed opaque planar shutter blades, each having an aperture and being arranged for reciprocal linear movement is disclosed. A pair of rotary solenoids, each connected to one of the blades by a linkage and arranged to be actuated separately at a predetermined interval is provided. An inertia damper and stop plate is built into each solenoid to prevent rebound

    A Test of Habitat Evaluation Models Using Avian Densities

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    Identifying Priority Conservation Areas and Strategies for Myotis sodalis (Chiroptera: Vespertilionidae) via Habitat and Connectivity Modeling

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    Myotis sodalis, the Indiana bat, is a federally endangered bat species in the United States of America (USA). Conservation efforts are typically focused at identified maternity sites at local scales, however, the species is a regional migrant that interacts with its environment at multiple spatial scales. We are limited in our knowledge of landscape-level requirements of this species, especially in large areas such as Illinois, USA, where a wide range of environmental and landscape conditions exist. Many previous M. sodalis habitat studies have limited their focus to smaller spatial scales. Due to limitations in funding, personnel, and time, it is imperative we understand both microhabitat and landscape-level habitat preferences to prioritize effective adaptive management strategies to maximize return on conservation investment. Our goals were to 1) identify the main factors that influence the distribution of maternity colonies across the Illinois landscape, 2) map the distribution of suitable habitat, 3) identify habitat patches that are important to conserve for retaining the functional connectivity of all habitat, and 4) identify state and federally-owned and/or managed lands that contain optimal habitat to highlight areas to focus conservation investments. Using 30 years of maternity occurrence data, we created Habitat Suitability Models (HSMs) and identified factors influencing the distribution of M. sodalis. We combined plausible models to map suitable maternity habitat across the study area. Using graph theory, we conducted a connectivity analysis on optimal habitat patches to rank them according to Probability of Connectivity-associated metrics. Our models indicated that M. sodalis require complex landscape-level habitat features, including limited agriculture, more forest and forest edge, proximity to medium-sized water bodies, lower elevations, and limited urban development. In addition, areas farther from major roads and closer to hibernation sites provide better habitat. One-third of Illinois is suitable maternity habitat for M. sodalis and many optimal patches occur within protected areas. We revealed that many habitat patches not only are important for hosting maternity colonies, but also are necessary components for bats migrating from hibernation sites to reach other maternity habitat patches. Our models allowed us to develop conservation strategies to recommend for improving maternity habitat suitability and connectivity in priority areas to aid in the recovery of this imperiled bat species

    Detection of bacterial spores with lanthanide-macrocycle binary complexes

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    The detection of bacterial spores via dipicolinate-triggered lanthanide luminescence has been improved in terms of detection limit, stability, and susceptibility to interferents by use of lanthanide−macrocycle binary complexes. Specifically, we compared the effectiveness of Sm, Eu, Tb, and Dy complexes with the macrocycle 1,4,7,10-tetraazacyclododecane-1,7-diacetate (DO2A) to the corresponding lanthanide aquo ions. The Ln(DO2A)^+ binary complexes bind dipicolinic acid (DPA), a major constituent of bacterial spores, with greater affinity and demonstrate significant improvement in bacterial spore detection. Of the four luminescent lanthanides studied, the terbium complex exhibits the greatest dipicolinate binding affinity (100-fold greater than Tb^(3+) alone, and 10-fold greater than other Ln(DO2A)^+ complexes) and highest quantum yield. Moreover, the inclusion of DO2A extends the pH range over which Tb−DPA coordination is stable, reduces the interference of calcium ions nearly 5-fold, and mitigates phosphate interference 1000-fold compared to free terbium alone. In addition, detection of Bacillus atrophaeus bacterial spores was improved by the use of Tb(DO2A)^+, yielding a 3-fold increase in the signal-to-noise ratio over Tb^(3+). Out of the eight cases investigated, the Tb(DO2A)^+ binary complex is best for the detection of bacterial spores

    Sex-Specific Differences in Shoaling Affect Parasite Transmission in Guppies

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    Background: Individuals have to trade-off the costs and benefits of group membership during shoaling behaviour. Shoaling can increase the risk of parasite transmission, but this cost has rarely been quantified experimentally. Guppies (Poecilia reticulata) are a model system for behavioural studies, and they are commonly infected by gyrodactylid parasites, notorious fish pathogens that are directly transmitted between guppy hosts. Methodology/Principal Findings:Parasite transmission in single sex shoals of male and female guppies were observed using an experimental infection of Gyrodactylus turnbulli. Parasite transmission was affected by sex-specific differences in host behaviour, and significantly more parasites were transmitted when fish had more frequent and more prolonged contact with each other. Females shoaled significantly more than males and had a four times higher risk to contract an infection. Conclusions/Significance: Intersexual differences in host behaviours such as shoaling are driven by differences in natural and sexual selection experienced by both sexes. Here we show that the potential benefits of an increased shoaling tendency are traded off against increased risks of contracting an infectious parasite in a group-living species

    Apparent interspecific transmission of Aphanomyces astaci from invasive signal to virile crayfish in a sympatric wild population

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    The crayfish plague pathogen (Aphanomyces astaci) causes mass mortalities of European crayfish when transmitted from its original North American crayfish hosts. Little is known, however, about interspecific transmission of the pathogen between different American crayfish species, although evidence from trade of ornamental crayfish suggests this may happen in captivity. We screened signal and virile crayfish for A. astaci at allopatric and sympatric sites in a UK river. Whilst the pathogen was detected in signal crayfish from both sites, infected virile crayfish were only found in sympatry. Genotyping of A. astaci from virile crayfish suggested the presence of a strain related to one infecting British signal crayfish. We conclude that virile crayfish likely contracted A. astaci interspecifically from infected signal crayfish. Interspecific transmission of A. astaci strains differing in virulence between American carrier species may influence the spread of this pathogen in open waters with potential exacerbated effects on native European crayfish

    Getting into hot water:sick guppies frequent warmer thermal conditions

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    Ectotherms depend on the environmental temperature for thermoregulation and exploit thermal regimes that optimise physiological functioning. They may also frequent warmer conditions to up-regulate their immune response against parasite infection and/or impede parasite development. This adaptive response, known as ‘behavioural fever’, has been documented in various taxa including insects, reptiles and fish, but only in response to endoparasite infections. Here, a choice chamber experiment was used to investigate the thermal preferences of a tropical freshwater fish, the Trinidadian guppy (Poecilia reticulata), when infected with a common helminth ectoparasite Gyrodactylus turnbulli, in female-only and mixed-sex shoals. The temperature tolerance of G. turnbulli was also investigated by monitoring parasite population trajectories on guppies maintained at a continuous 18, 24 or 32 °C. Regardless of shoal composition, infected fish frequented the 32 °C choice chamber more often than when uninfected, significantly increasing their mean temperature preference. Parasites maintained continuously at 32 °C decreased to extinction within 3 days, whereas mean parasite abundance increased on hosts incubated at 18 and 24 °C. We show for the first time that gyrodactylid-infected fish have a preference for warmer waters and speculate that sick fish exploit the upper thermal tolerances of their parasites to self medicate
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