A laboratory system for examining the influence of light on diel activity of stream invertebrates

I describe a laboratory system for investigating the role of light as a proximate cue for diel changes in locomotor activity and vertical location on the substrate of stream macro-invertebrates. The system consisted of computer-controlled halogen lamps positioned over a laboratory stream in which video-recordings were made of Stenonema modestum mayfly nymphs located on the undersides of unglazed tile substrates. Locomotor activity of study organisms in response to light changes were quantified during computer-programmed and reproducible light/dark (LD) cycles. The system provided the flexibility to simulate a variety of light environments so that the separate influences of light intensity and light change on diel activities of individuals and populations could be examined, which is difficult under natural light conditions. As a group, nymphs responded similarly to simulated twilight (light decrease from 7.9 × 102 to 6.9 × 10−2 μW cm−2 at a constant –1.9 × 10−3 s−1 rate of relative light change) and to natural twilight, suggesting that proposed mechanisms of light control of diel activities in nature can be adequately tested in the simulated environment. However, locomotor activity and vertical movements among individual mayflies were highly variable under controlled conditions, suggesting that physiological differences influence their responses to environmental conditions

Science by Smartphone

A national effort aimed at getting citizens to use their smartphone cameras and other mobile, handheld devices for real science is underway, and EOS researchers are part of the vanguard

Solid state switch

Solid state switching circuit design to increase current capacity of low rated relay contact

The use of an artificial light system to assess the influence of relative light change on diel activity cycles of nymphs of the mayfly, Stenonema modestum, in the presence and absence of predators

A mechanism by which light controls diel changes in locomotor activity and surface location of mayfly nymphs (Stenonema modestum Banks), named the Stimulus-based Timing and Activity-Rate (STAR) Model, was tested. Nymph movements were video-recorded in time-lapse from underneath unglazed artificial substrates in a laboratory stream. Light/dark cycles were simulated using computer-controlled halogen lamps. Light increases and decreases were generated to maintain constant rates of relative light change throughout simulated twilight periods. Nymph locomotor activity and position on the substrate were measured in response to rate of light change. Experiments tested whether adaptation light intensity (10\sp{-4} or 10\sp{-6} W cm\sp{-2}), time of day (AM or PM), length of the period of light change, or predators, altered nymph responses to light change. Timing of both heightened nocturnal locomotor activity and leaving the substrate were significantly correlated (R\sp2 =.93; p $\u3c$ 0.001 and R\sp2 =.71; p $\u3c$ 0.004, respectively) with rate of relative light decrease. Rate of change in light was a correlated with the difference between daytime and nighttime locomotor activity (R\sp2 =.38, p $\u3c$ 0.02). The onset of nocturnal locomotor activity was advanced when nymphs were adapted to a low daytime light intensity. Lowered daytime light did not change the time mayflies left the undersides of the substrate. There was no difference in the locomotor activity response between AM and PM experiments, but significantly greater numbers of nymphs left the substrate undersides during simulated twilight in the PM experiments (p $\u3c$ 0.009, F\sb{1.14} = 9.3. The difference between daytime and nighttime locomotor activity diminished during shortened periods of light decrease. When the time intervals over which light was reduced became smaller than the latency period of the response, there was no nocturnal increase in locomotor activity. Nymphs left the substrate undersides regardless of the length of time over which light was reduced. Locomotor activity was greater in the presence of fish odor (Notropis comutus and Rhinichthys cataractae) than in water not containing predators. Locomotor activity was reduced during the daytime in the presence of Paragnetina media stoneflies. Synergistic effects between fish and stoneflies resulted in differences in the timing and locomotor activity of both stoneflies and mayflies

Diversity of O Antigens within the Genus Cronobacter: from Disorder to Order

Cronobacter species are Gram-negative opportunistic pathogens that can cause serious infections in neonates. The lipopolysaccharides (LPSs) that form part of the outer membrane of such bacteria are possibly related to the virulence of particular bacterial strains. However, currently there is no clear overview of O-antigen diversity within the various Cronobacter strains and links with virulence. In this study, we tested a total of 82 strains, covering each of the Cronobacter species. The nucleotide variability of the O-antigen gene cluster was determined by restriction fragment length polymorphism (RFLP) analysis. As a result, the 82 strains were distributed into 11 previously published serotypes and 6 new serotypes, each defined by its characteristic restriction profile. These new serotypes were confirmed using genomic analysis of strains available in public databases: GenBank and PubMLST Cronobacter. Laboratory strains were then tested using the current serotype-specific PCR probes. The results show that the current PCR probes did not always correspond to genomic O-antigen gene cluster variation. In addition, we analyzed the LPS phenotype of the reference strains of all distinguishable serotypes. The identified serotypes were compared with data from the literature and the MLST database (www.pubmlst.org/cronobacter/). Based on the findings, we systematically classified a total of 24 serotypes for the Cronobacter genus. Moreover, we evaluated the clinical history of these strains and show that Cronobacter sakazakii O2, O1, and O4, C. turicensis O1, and C. malonaticus O2 serotypes are particularly predominant in clinical cases

Interactions between carbon and nitrogen dynamics in estimating net primary productivity for potential vegetation in North America

We use the terrestrial ecosystem model (TEM), a process-based model, to investigate how interactions between carbon (C) and nitrogen (N) dynamics affect predictions of net primary productivity (NPP) for potential vegetation in North America. Data on pool sizes and fluxes of C and N from intensively studied field sites are used to calibrate the model for each of 17 non-wetland vegetation types. We use information on climate, soils, and vegetation to make estimates for each of 11,299 non-wetland, 0.5° latitude × 0.5° longitude, grid cells in North America. The potential annual NPP and net N mineralization (NETNMIN) of North America are estimated to be 7.032 × 1015 g C yr−1 and 104.6 × 1012 g N yr−1, respectively. Both NPP and NETNMIN increase along gradients of increasing temperature and moisture in northern and temperate regions of the continent, respectively. Nitrogen limitation of productivity is weak in tropical forests, increasingly stronger in temperate and boreal forests, and very strong in tundra ecosystems. The degree to which productivity is limited by the availability of N also varies within ecosystems. Thus spatial resolution in estimating exchanges of C between the atmosphere and the terrestrial biosphere is improved by modeling the linkage between C and N dynamics. We also perform a factorial experiment with TEM on temperate mixed forest in North America to evaluate the importance of considering interactions between C and N dynamics in the response of NPP to an elevated temperature of 2°C. With the C cycle uncoupled from the N cycle, NPP decreases primarily because of higher plant respiration. However, with the C and N cycles coupled, NPP increases because productivity that is due to increased N availability more than offsets the higher costs of plant respiration. Thus, to investigate how global change will affect biosphere-atmosphere interactions, process-based models need to consider linkages between the C and N cycles

A Fast Sextupole Probe for Snapback Measurement in the LHC Dipoles

In superconducting particle accelerators a fast change of the magnetic field occurs during the first few seconds after the start of an energy ramp. Standard magnetic measurements using a coil rotating at 1 Hz do not have the time resolution required to completely resolve this phase, usually called snapback. For this reason we have developed a new and fast system dedicated to sextupole measurements. The basic component consists of three Hall plates mounted on a ring. In an ideal case this arrangement compensates the main dipole field and produces a signal proportional to the sextupole only. Mechanical tolerances and differences in the sensitivity of the Hall plates are compensated by instrumentation amplifiers and an in situ fine adjustment of the probe orientation. Using this hybrid compensation technique we have measured sextupole variations in an LHC dipole prototype during snapback at a rate of 5 Hz. In this paper we present details on the device and the results of our measurements

shape to color associations in non synesthetes evidence for emotional mediation

4 Shape Features: Curviness: Curved, angular Symmetry: Asymmetric, symmetric Closure: Open, intersecting-once, intersecting>1 # of Line-Segments: 2, 3, 8 line-segments 8 Hues: Red, Yellow, Green, Blue, Orange, Chartreuse, Cyan, Purple 4 Saturation/Lightness levels ("cuts"): Saturated, Light, Muted, Dark + 5 Achromatic Colors: White, Black, Light, Medium, & Dark Gray 1a 1c 2a 2c 3a 3c 4a 4c 5a 5c 6

Reducing the Effects of PCR Amplification and Sequencing Artifacts on 16S rRNA-Based Studies

The advent of next generation sequencing has coincided with a growth in interest in using these approaches to better understand the role of the structure and function of the microbial communities in human, animal, and environmental health. Yet, use of next generation sequencing to perform 16S rRNA gene sequence surveys has resulted in considerable controversy surrounding the effects of sequencing errors on downstream analyses. We analyzed 2.7×10[superscript 6] reads distributed among 90 identical mock community samples, which were collections of genomic DNA from 21 different species with known 16S rRNA gene sequences; we observed an average error rate of 0.0060. To improve this error rate, we evaluated numerous methods of identifying bad sequence reads, identifying regions within reads of poor quality, and correcting base calls and were able to reduce the overall error rate to 0.0002. Implementation of the PyroNoise algorithm provided the best combination of error rate, sequence length, and number of sequences. Perhaps more problematic than sequencing errors was the presence of chimeras generated during PCR. Because we knew the true sequences within the mock community and the chimeras they could form, we identified 8% of the raw sequence reads as chimeric. After quality filtering the raw sequences and using the Uchime chimera detection program, the overall chimera rate decreased to 1%. The chimeras that could not be detected were largely responsible for the identification of spurious operational taxonomic units (OTUs) and genus-level phylotypes. The number of spurious OTUs and phylotypes increased with sequencing effort indicating that comparison of communities should be made using an equal number of sequences. Finally, we applied our improved quality-filtering pipeline to several benchmarking studies and observed that even with our stringent data curation pipeline, biases in the data generation pipeline and batch effects were observed that could potentially confound the interpretation of microbial community data.National Institutes of Health (U.S.) (1R01HG005975-01)National Science Foundation (U.S.) (award #0743432)National Institutes of Health (U.S.) (grant NIHU54HG004969