246 research outputs found

    Expected size of a tree in the fixed point forest

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    We study the local limit of the fixed-point forest, a tree structure associated to a simple sorting algorithm on permutations. This local limit can be viewed as an infinite random tree that can be constructed from a Poisson point process configuration on [0,1]N[0,1]^\mathbb{N}. We generalize this random tree, and compute the expected size and expected number of leaves of a random rooted subtree in the generalized version. We also obtain bounds on the variance of the size.Comment: 14 page

    Sizing individual dielectric nanoparticles with quantitative differential interference contrast microscopy

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    We report a method to measure the size of single dielectric nanoparticles with high accuracy and precision using quantitative differential interference contrast (DIC) microscopy. Dielectric nanoparticles are detected optically by the conversion of the optical phase change into an intensity change using DIC. Phase images of individual nanoparticles were retrieved from DIC by Wiener filtering, and a quantitative methodology to extract nanoparticle sizes was developed. Using polystyrene beads of 100 nm radius as size standard, we show that the method determines this radius within a few nm accuracy. The smallest detectable polystyrene bead is limited by background and shot-noise, which depend on acquisition and analysis parameters, including the objective numerical aperture, the DIC phase offset, and the refractive index contrast between particles and their surrounding. A sensitivity limit potentially reaching down to 1.8 nm radius was inferred. As application example, individual nanodiamonds with nominal sizes below 50 nm were measured, and were found to have a nearly exponential size distribution with 28 nm mean value. Considering the importance of dielectric nanoparticles in many fields, from naturally occurring virions to polluting nanoplastics, the proposed method could offer a powerful quantitative tool for nanoparticle analysis, combining accuracy, sensitivity and high-throughput with widely available and easy-to-use DIC microscop

    Measurements of growing Holstein and Jersey cattle on Missouri farms.|Prediction charts for growth of cattle.

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    Includes bibliographical references (pages 29-30)

    Quantitative measurement of graphitic sp2 on single nanodiamonds with sub-monolayer sensitivity using differential interference contrast and photo-thermal microscopy

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    The surface of nanodiamonds is prone to be decorated with a graphitic layer due to the thermodynamic instability of diamond versus graphite. Notably, this surface layer affects the zeta-potential of nanodiamonds controlling their colloidal stability, modulates the charging of embedded nitrogen vacancy centres used for sensing and quantum technology, and introduces an optical absorption which leads to heating and destruction of nanodiamonds under intense laser irradiation. Physical and chemical treatments to reduce the graphitic carbon are available, but a sensitive method to measure this graphitic layer on single nanodiamonds is lacking. Here, we demonstrate a non-destructive method to quantitatively determine the graphitic carbon correlatively with the nanodiamond size, on individual nanodiamonds. The method allows determining the fraction of graphitic sp to diamond sp bonded atoms, and estimating the sp surface layer thickness. We investigated milled nanodiamonds, both untreated and chemically treated to remove sp . We found that untreated nanodiamonds were covered by the equivalent of a single monolayer, which was reduced to 10% of a monolayer for treated nanodiamonds. In both cases, significant variations between individual nanodiamonds were observed. The minimum number of bonded atoms detectable under the measurement conditions reported here was found to be

    The Culture of Primary Motor and Sensory Neurons in Defined Media on Electrospun Poly-L-lactide Nanofiber Scaffolds

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    Electrospinning is a technique for producing micro- to nano-scale fibers. Fibers can be electrospun with varying degrees of alignment, from highly aligned to completely random. In addition, fibers can be spun from a variety of materials, including biodegradable polymers such as poly-L-lactic acid (PLLA). These characteristics make electrospun fibers suitable for a variety of scaffolding applications in tissue engineering. Our focus is on the use of aligned electrospun fibers for nerve regeneration. We have previously shown that aligned electrospun PLLA fibers direct the outgrowth of both primary sensory and motor neurons in vitro. We maintain that the use of a primary cell culture system is essential when evaluating biomaterials to model real neurons found in vivo as closely as possible. Here, we describe techniques used in our laboratory to electrospin fibrous scaffolds and culture dorsal root ganglia explants, as well as dissociated sensory and motor neurons, on electrospun scaffolds. However, the electrospinning and/or culture techniques presented here are easily adapted for use in other applications

    Angiographic Findings and Outcome in Diabetec Patients Treated With Thrombolytic Therapy for Acute Myocardial Infarction: The GUSTO-I Experience

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    OBJECTIVES: This study sought to determine whether diabetes mellitus, in the setting of thrombolysis for acute myocardial infarction, affects 1) early infarct-related artery patency and reocclusion rates; and 2) global and regional ventricular function indexes. We also sought to assess whether angiographic or baseline clinical variables, or both, can account for the known excess mortality after myocardial infarction in the diabetic population. BACKGROUND: Mortality after acute myocardial infarction in patients with diabetes is approximately twice that of nondiabetic patients. It is uncertain whether this difference in mortality is due to a lower rate of successful thrombolysis, increased reocclusion after successful thrombolysis, greater ventricular injury or a more adverse angiographic or clinical profile in diabetic patients. METHODS: Patency rates and global and regional left ventricular function were determined in patients enrolled in the GUSTO-I Angiographic Trial. Thirty-day mortality differences between those with and without diabetes were compared. RESULTS: The diabetic cohort had a significantly higher proportion of female and elderly patients, and th

    Elevated type-17 cytokines are present in Axial Spondyloarthritis stool

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    Axial Spondyloarthritis (axSpA) is characterized by type-17 immune-driven joint inflammation, and intestinal inflammation is present in around 70% of patients. In this study, we asked whether axSpA stool contained Th17-associated cytokines and whether this related to systemic Th17 activation. We measured stool cytokine and calprotectin levels by ELISA and found that patients with axSpA have increased stool IL-17A, IL-23, GM-CSF, and calprotectin. We further identified increased levels of circulating IL-17A+ and IL-17F+ T helper cell lymphocytes in patients with axSpA compared to healthy donors. We finally assessed stool metabolites by unbiased nuclear magnetic resonance (NMR) spectroscopy and found that multiple stool amino acids were negatively correlated with stool IL-23 concentrations. These data provide evidence of type-17 immunity in the intestinal lumen, and suggest its association with microbial metabolism in the intestine

    Seabirds show foraging site and route fidelity but demonstrate flexibility in response to local information

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    •Background: Fidelity to a given foraging location or route may be beneficial when environmental conditions are predictable but costly if conditions deteriorate or become unpredictable. Understanding the magnitude of fidelity displayed by different species and the processes that drive or erode it is therefore vital for understanding how fidelity may shape the demographic consequences of anthropogenic change. In particular, understanding the information that individuals may use to adjust their fidelity will facilitate improved predictions of how fidelity may change as environments change and the extent to which it will buffer individuals against such changes. •Methods: We used movement data collected during the breeding season across eight years for common guillemots, Atlantic puffins, razorbills, and black-legged kittiwakes breeding on the Isle of May, Scotland to understand: (1) whether foraging site/route fidelity occurred within and between years, (2) whether the degree of fidelity between trips was predicted by personal foraging effort, and (3) whether different individuals made more similar trips when they overlapped in time at the colony prior to departure and/or when out at sea suggesting the use of the same local environmental cues or information on the decisions made by con- and heterospecifics. •Results: All species exhibited site and route fidelity both within- and between-years, and fidelity between trips in guillemots and razorbills was related to metrics of foraging effort, suggesting they adjust fidelity to their personal foraging experience. We also found evidence that individuals used local environmental cues of prey location or availability and/or information gained by observing conspecifics when choosing foraging routes, particularly in puffins, where trips of individuals that overlapped temporally at the colony or out at sea were more similar. •Conclusions: The fidelity shown by these seabird species has the potential to put them at greater risk in the face of environmental change by driving individuals to continue using areas being degraded by anthropogenic pressures. However, our results suggest that individuals show some flexibility in their fidelity, which may promote resilience under environmental change. The benefits of this flexibility are likely to depend on numerous factors, including the rapidity and spatial scale of environmental change and the reliability of the information individuals use to choose foraging sites or routes, thus highlighting the need to better understand how organisms combine cues, prior experience, and other sources of information to make movement decisions
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