509 research outputs found

    Status of the tiger beetle Cicindela hirticollis Say (Coleoptera: Cicindelidae) in New York City and on Long Island, New York, USA

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    Coastal species are under considerable threat from recreational activities and climate change. The tiger beetle Cicindela hirticollis Say (Coleoptera: Cicindelidae) was recorded historically from 30 locations along the shores of New York City and Long Island, New York. We conducted surveys for extant populations of this species at 40 sites from 1989 to 2010. Adults of C. hirticollis were found at 13 beaches. Only four sites had 40 or more adults of C. hirticollis active at the time the beach was surveyed. No beetles were detected on the large coastal beaches that were formerly occupied by this species. Many coastal beaches of New York receive heavy human foot and vehicle traffic and are therefore unlikely to provide suitable habitat for C. hirticollis without a shift in beach management that recognizes the potential of some beaches as wilderness systems capable of supporting the full array of beach-dependent species

    Status of the tiger beetle \u3ci\u3eCicindela hirticollis\u3c/i\u3e Say (Coleoptera: Cicindelidae) in New York City and on Long Island, New York, USA

    Get PDF
    Coastal species are under considerable threat from recreational activities and climate change. The tiger beetle Cicindela hirticollis Say (Coleoptera: Cicindelidae) was recorded historically from 30 locations along the shores of New York City and Long Island, New York. We conducted surveys for extant populations of this species at 40 sites from 1989 to 2010. Adults of C. hirticollis were found at 13 beaches. Only four sites had 40 or more adults of C. hirticollis active at the time the beach was surveyed. No beetles were detected on the large coastal beaches that were formerly occupied by this species. Many coastal beaches of New York receive heavy human foot and vehicle traffic and are therefore unlikely to provide suitable habitat for C. hirticollis without a shift in beach management that recognizes the potential of some beaches as wilderness systems capable of supporting the full array of beach-dependent species

    Aptamer-Based Detection of Ampicillin in Urine Samples

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    The misuse of antibiotics in health care has led to increasing levels of drug resistant infections (DRI's) occurring in the general population. Most technologies developed for the detection of DRI's typically focus on phenotyping or genotyping bacterial resistance rather than on the underlying cause and spread of DRI's; namely the misuse of antibiotics. An aptameric based assay has been developed for the monitoring of ampicillin in urine samples, for use in determining optimal antibiotic dosage and monitoring patient compliance with treatment. The fluorescently labelled aptamers were shown to perform optimally at pH 7, ideal for buffered clinical urine samples, with limits of detection as low as 20.6 nM, allowing for determination of ampicillin in urine in the clinically relevant range of concentrations (100 nM to 100 µM). As the assay requires incubation for only 1 h with a small sample volume, 50 to 150 µL, the test would fit within current healthcare pathways, simplifying the adoption of the technology

    Status of the tiger beetle \u3ci\u3eCicindela hirticollis\u3c/i\u3e Say (Coleoptera: Cicindelidae) in New York City and on Long Island, New York, USA

    Get PDF
    Coastal species are under considerable threat from recreational activities and climate change. The tiger beetle Cicindela hirticollis Say (Coleoptera: Cicindelidae) was recorded historically from 30 locations along the shores of New York City and Long Island, New York. We conducted surveys for extant populations of this species at 40 sites from 1989 to 2010. Adults of C. hirticollis were found at 13 beaches. Only four sites had 40 or more adults of C. hirticollis active at the time the beach was surveyed. No beetles were detected on the large coastal beaches that were formerly occupied by this species. Many coastal beaches of New York receive heavy human foot and vehicle traffic and are therefore unlikely to provide suitable habitat for C. hirticollis without a shift in beach management that recognizes the potential of some beaches as wilderness systems capable of supporting the full array of beach-dependent species

    Jet Physics from Static Charges in AdS

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    Soft interactions with high-energy jets are explored in radial coordinates which exploit the approximately conformal behavior of perturbative gauge theories. In these coordinates, the jets, approximated by Wilson lines, become static charges in Euclidean AdS. The anomalous dimension of the corresponding Wilson line operator is then determined by the potential energy of the charges. To study these Wilson lines we introduce a "conformal gauge" which does not have kinetic mixing between radial and angular directions, and show that a number of properties of Wilson lines are reproduced through relatively simple calculations. For example, certain non-planar graphs involving multiple Wilson lines automatically vanish. We also discuss the linear growth of the charges' imaginary potential energy with separation, and a relationship between Wilson line diagrams and Witten diagrams.Comment: 34 pages, 7 figures; V2: minor edits, added reference

    Tree Species Traits Influence Soil Physical, Chemical, and Biological Properties in High Elevation Forests

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    BACKGROUND: Previous studies have shown that plants often have species-specific effects on soil properties. In high elevation forests in the Southern Rocky Mountains, North America, areas that are dominated by a single tree species are often adjacent to areas dominated by another tree species. Here, we assessed soil properties beneath adjacent stands of trembling aspen, lodgepole pine, and Engelmann spruce, which are dominant tree species in this region and are distributed widely in North America. We hypothesized that soil properties would differ among stands dominated by different tree species and expected that aspen stands would have higher soil temperatures due to their open structure, which, combined with higher quality litter, would result in increased soil respiration rates, nitrogen availability, and microbial biomass, and differences in soil faunal community composition. METHODOLOGY/PRINCIPAL FINDINGS: We assessed soil physical, chemical, and biological properties at four sites where stands of aspen, pine, and spruce occurred in close proximity to one-another in the San Juan Mountains, Colorado. Leaf litter quality differed among the tree species, with the highest nitrogen (N) concentration and lowest lignin:N in aspen litter. Nitrogen concentration was similar in pine and spruce litter, but lignin:N was highest in pine litter. Soil temperature and moisture were highest in aspen stands, which, in combination with higher litter quality, probably contributed to faster soil respiration rates from stands of aspen. Soil carbon and N content, ammonium concentration, and microbial biomass did not differ among tree species, but nitrate concentration was highest in aspen soil and lowest in spruce soil. In addition, soil fungal, bacterial, and nematode community composition and rotifer, collembolan, and mesostigmatid mite abundance differed among the tree species, while the total abundance of nematodes, tardigrades, oribatid mites, and prostigmatid mites did not. CONCLUSIONS/SIGNIFICANCE: Although some soil characteristics were unaffected by tree species identity, our results clearly demonstrate that these dominant tree species are associated with soils that differ in several physical, chemical, and biotic properties. Ongoing environmental changes in this region, e.g. changes in fire regime, frequency of insect outbreaks, changes in precipitation patterns and snowpack, and land-use change, may alter the relative abundance of these tree species over coming decades, which in turn will likely alter the soils

    Biofilm Structure Promotes Coexistence of Phage-Resistant and Phage-Susceptible Bacteria

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    Encounters among bacteria and their viral predators (bacteriophages) are among the most common ecological interactions on Earth. These encounters are likely to occur with regularity inside surface-bound communities that microbes most often occupy in natural environments. Such communities, termed biofilms, are spatially constrained: interactions become limited to near neighbors, diffusion of solutes and particulates can be reduced, and there is pronounced heterogeneity in nutrient access and physiological state. It is appreciated from prior theoretical work that phage-bacteria interactions are fundamentally different in spatially structured contexts, as opposed to well-mixed liquid culture. Spatially structured communities are predicted to promote the protection of susceptible host cells from phage exposure, and thus weaken selection for phage resistance. The details and generality of this prediction in realistic biofilm environments, however, are not known. Here, we explore phage-host interactions using experiments and simulations that are tuned to represent the essential elements of biofilm communities. Our simulations show that in biofilms, phage-resistant cells-as their relative abundance increases-can protect clusters of susceptible cells from phage exposure, promoting the coexistence of susceptible and phage-resistant bacteria under a large array of conditions. We characterize the population dynamics underlying this coexistence, and we show that coexistence is recapitulated in an experimental model of biofilm growth measured with confocal microscopy. Our results provide a clear view into the dynamics of phage resistance in biofilms with single-cell resolution of the underlying cell-virion interactions, linking the predictions of canonical theory to realistic models and in vitro experiments of biofilm growth. IMPORTANCE In the natural environment, bacteria most often live in communities bound to one another by secreted adhesives. These communities, or biofilms, play a central role in biogeochemical cycling, microbiome functioning, wastewater treatment, and disease. Wherever there are bacteria, there are also viruses that attack them, called phages. Interactions between bacteria and phages are likely to occur ubiquitously in biofilms. We show here, using simulations and experiments, that biofilms will in most conditions allow phage-susceptible bacteria to be protected from phage exposure, if they are growing alongside other cells that are phage resistant. This result has implications for the fundamental ecology of phage-bacteria interactions, as well as the development of phage-based antimicrobial therapeutics

    A surface code quantum computer in silicon

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    The exceptionally long quantum coherence times of phosphorus donor nuclear spin qubits in silicon, coupled with the proven scalability of silicon-based nano-electronics, make them attractive candidates for large-scale quantum computing. However, the high threshold of topological quantum error correction can only be captured in a two-dimensional array of qubits operating synchronously and in parallel—posing formidable fabrication and control challenges. We present an architecture that addresses these problems through a novel shared-control paradigm that is particularly suited to the natural uniformity of the phosphorus donor nuclear spin qubit states and electronic confinement. The architecture comprises a two-dimensional lattice of donor qubits sandwiched between two vertically separated control layers forming a mutually perpendicular crisscross gate array. Shared-control lines facilitate loading/unloading of single electrons to specific donors, thereby activating multiple qubits in parallel across the array on which the required operations for surface code quantum error correction are carried out by global spin control. The complexities of independent qubit control, wave function engineering, and ad hoc quantum interconnects are explicitly avoided. With many of the basic elements of fabrication and control based on demonstrated techniques and with simulated quantum operation below the surface code error threshold, the architecture represents a new pathway for large-scale quantum information processing in silicon and potentially in other qubit systems where uniformity can be exploited
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