626 research outputs found

    Analyzing the footprints of near-surface aqueous turbulence: An image processing-based approach

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    In this contribution, a detailed investigation of surface thermal patterns on the water surface is presented, with wind speeds ranging from 1 to 7 m s  − 1 and various surface conditions. Distinct structures can be observed on the surface—small-scale short-lived structures termed fish scales and larger-scale cold streaks that are consistent with the footprints of Langmuir circulations. The structure of the surface heat pattern depends strongly on wind-induced stress. Consistent behavior regarding the spacing of cold streaks can be observed in a range of laboratory facilities when expressed as a function of water-sided friction velocity, u * . This behavior systematically decreased until a point of saturation at u *  = 0.7 cm/s. We present a new image processing-based approach to the analysis of the spacing of cold streaks based on a machine learning approach to classify the thermal footprints of near-surface turbulence. Comparison is made with studies of Langmuir circulation and the following key points are found. Results suggest a saturation in the tangential stress, anticipating that similar behavior will be observed in the open ocean. A relation to Langmuir numbers shows that thermal footprints in infrared images are consistent with Langmuir circulations and depend strongly on wind wave conditions

    How large is the gap between present and efficient transport prices in Europe?

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    In this paper we analyse the gap between present transport prices and efficient transport prices. Efficient transport prices are those prices that maximise economic welfare, including external costs (congestion, air pollution, accidents). The methodology is applied to six urban and interregional case studies using one common optimal pricing model. The case studies cover passenger as well as freight transport and cover all modes. We find that prices need to be raised most for peak urban passenger car transport and to a lesser extent for interregional road transport. Optimal pricing results for public transport are more mixed. We show that current external costs on congested roads are a bad guide for optimal taxes and tolls: the optimal toll that takes into account the reaction of demand is often less than one third of the present marginal external cost.transport pricing; external costs; social costs; congestion pricing

    A molecular phylogeny and classification of the largely succulent and mainly African Euphorbia subg. Athymalus (Euphorbiaceae)

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    Euphorbia subg. Athymalus consists of approximately 150 species and is one of the four main lineages that comprise the species–rich genus Euphorbia. Most species in the subgenus are stem succulents with greatly reduced leaves, but there are also leafy herbs, shrubs, trees and geophytes. The subgenus is restricted to arid regions of the Old World. Most species are found in sub–Saharan Africa, with one in Macaronesia and adjacent parts of western Africa, a few in the Arabian Peninsula (one of which extends into Iran) and one native to Madagascar. Twenty–three species are endemic to the northeastern Horn of Africa (SE Ethiopia, Socotra, Somalia), while 72 species are restricted to southern Africa (including Botswana, Lesotho, Namibia, South Africa and Swaziland). Sixty of those are endemic to South Africa alone, where they are particularly associated with the semi–arid west and south of the country in the Greater Cape Floristic Region and the Nama Karoo Region. We sampled 88 species and analyzed data from the nuclear ribosomal ITS and plastid ndhF regions. Analyses of the separate and combined datasets produced phylogenies that confirm the monophyly of E. subg. Athymalus and the placement of E. antso from Madagascar as sister to the rest of the subgenus. Our analyses also show that the subgenus consists of a grade of early–diverging lineages that are relatively poor in species and that the major radiation of succulent species in southern Africa forms a highly supported clade (E. sect. Anthacanthae). Species–level relationships within this southern African clade, however, remain largely unresolved. Our phylogenetic hypotheses allow us to propose a new classification for E. subg. Athymalus where seven sections are recognized, two of which are newly described. The large southern African E. sect. Anthacanthae is further divided into five subsections, and four series are recognized in E. subsect. Florispinae.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147157/1/tax6269.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147157/2/tax6269-sup-001-pdf.pd

    Deep Ensemble Analysis for Imaging X-ray Polarimetry

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    We present a method for enhancing the sensitivity of X-ray telescopic observations with imaging polarimeters, with a focus on the gas pixel detectors (GPDs) to be flown on the Imaging X-ray Polarimetry Explorer (IXPE). Our analysis determines photoelectron directions, X-ray absorption points and X-ray energies for 1-9 keV event tracks, with estimates for both the statistical and model (reconstruction) uncertainties. We use a weighted maximum likelihood combination of predictions from a deep ensemble of ResNet convolutional neural networks, trained on Monte Carlo event simulations. We define a figure of merit to compare the polarization bias-variance trade-off in track reconstruction algorithms. For power-law source spectra, our method improves on the current planned IXPE analysis (and previous deep learning approaches), providing ~45% increase in effective exposure times. For individual energies, our method produces 20-30% absolute improvements in modulation factor for simulated 100% polarized events, while keeping residual systematic modulation within 1 sigma of the finite sample minimum. Absorption point location and photon energy estimates are also significantly improved. We have validated our method with sample data from real GPD detectors.Comment: 18 pages, 9 figures. Accepted to Nuclear Instruments and Methods in Physics Research Section A, Sep 202

    Functional inhibition of deep brain non-visual opsins facilitates acute long day induction of reproductive recrudescence in male Japanese quail  :Deep brain photoreceptors in birds

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    For nearly a century, we have known that brain photoreceptors regulate avian seasonal biology. Two photopigments, vertebrate ancient opsin (VA) and neuropsin (OPN5), provide possible molecular substrates for these photoreceptor pathways. VA fulfills many criteria for providing light input to the reproductive response, but a functional link has yet to be demonstrated. This study examined the role of VA and OPN5 in the avian photoperiodic response of Japanese quail (Coturnix japonica). Non-breeding male quail were housed under short days (6L:18D) and received an intracerebroventricular infusion of adeno-associated viral vectors with shRNAi that selectively inhibited either VA or OPN5. An empty viral vector acted as a control. Quail were then photostimulated (16L:8D) to stimulate gonadal growth. Two long days significantly increased pituitary thyrotrophin-stimulating hormone β-subunit (TSHβ) and luteinizing hormone β-subunit (LHβ) mRNA of VA shRNAi treated quail compared to controls. Furthermore, at one week there was a significant increase, compared to controls, in both hypothalamic gonadotrophin releasing hormone-I (GnRH-I) mRNA and paired testicular mass in VA shRNAi birds. Opn5 shRNAi facilitated the photoinduced increase in TSHβ mRNA at 2 days, but no other differences were identified compared to controls. Contrary to our expectations, the silencing of deep brain photoreceptors enhanced the response of the reproductive axis to photostimulation rather than preventing it. In addition, we show that VA opsin plays a dominant role in the light-dependent neuroendocrine control of seasonal reproduction in birds. Together our findings suggest the photoperiodic response involves at least two photoreceptor types and populations working together with VA opsin playing a dominant role

    Biola Hour Highlights, 1976 - 01

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    Essentials of Prayer by Al Sanders Titles of the Savior by Richard Chase Historic Reality and Prophetic Promise by Charles Feinberg Celebrating \u27Xmas\u27 by Samuel Sutherland A Unique Christmas by Glenn O\u27Neal Christmas Comparisons from John 12 by Ron Hafer Mary, the Mother of Jesus by Ernie Peirson My Peace I Give to You by Curtis Mitchell Mary by Lloyd Anderson Revelation by Lloyd Anderson Panel Discussion by Richard Chase, Charles Feinberg, and Samuel Sutherlandhttps://digitalcommons.biola.edu/bhhs/1023/thumbnail.jp

    Biola Hour Highlights, 1976 - 12

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    Daniel by Lloyd Anderson I Thessalonians by Lehman Strauss II Thessalonians by Lehman Strauss Faithfulness of God by Lehman Strauss Psalm 131 by Al Sanders Panel Discussion by Richard Chase, Charles Feinberg, and Samuel Sutherlandhttps://digitalcommons.biola.edu/bhhs/1034/thumbnail.jp
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