730 research outputs found

    Incorporating Animal Movement Into Distance Sampling

    Get PDF
    Distance sampling is a popular statistical method to estimate the density of wild animal populations. Conventional distance sampling represents animals as fixed points in space that are detected with an unknown probability that depends on the distance between the observer and the animal. Animal movement can cause substantial bias in density estimation. Methods to correct for responsive animal movement exist, but none account for nonresponsive movement independent of the observer. Here, an explicit animal movement model is incorporated into distance sampling, combining distance sampling survey data with animal telemetry data. Detection probability depends on the entire unobserved path the animal travels. The intractable integration over all possible animal paths is approximated by a hidden Markov model. A simulation study shows themethod to be negligibly biased (\u3c5%) in scenarioswhere conventional distance sampling overestimates abundance by up to 100%. The method is applied to line transect surveys (1999– 2006) of spotted dolphins (Stenella attenuata) in the eastern tropical Pacific where abundance is shown to be positively biased by 21% on average, which can have substantial impact on the population dynamics estimated from these abundance estimates and on the choice of statistical methodology applied to future surveys. Supplementary materials for this article, including a standardized description of the materials available for reproducing the work, are available as an online supplement

    An In Vitro Study Comparing Limited to Full Cementation of Polyethylene Glenoid Components

    Get PDF
    BACKGROUND: Glenoid component survival is critical to good long-term outcomes in total shoulder arthroplasty. Optimizing the fixation environment is paramount. The purpose of this study was to compare two glenoid cementing techniques for fixation in total shoulder arthroplasty. METHODS: Sixteen cadaveric specimens were randomized to receive peg-only cementation (CPEG) or full back-side cementation (CBACK). Physiological cyclic loading was performed and implant displacement was recorded using an optical tracking system. The cement mantle was examined with micro-computed tomography before and after cyclic loading. RESULTS: Significantly greater implant displacement away from the inferior portion of the glenoid was observed in the peg cementation group when compared to the fully cemented group during the physiological loading. The displacement was greatest at the beginning of the loading protocol and persisted at a diminished rate during the remainder of the loading protocol. Micro-CT scanning demonstrated that the cement mantle remained intact in both groups and that three specimens in the CBACK group demonstrated microfracturing in one area only. DISCUSSION: Displacement of the CPEG implants away from the inferior subchondral bone may represent a suboptimal condition for long-term implant survival. Cement around the back of the implant is suggested to improve initial stability of all polyethylene glenoid implants. CLINICAL RELEVANCE: Full cementation provides greater implant stability when compared to limited cementation techniques for insertion of glenoid implants. Loading characteristics are more favorable when cement is placed along the entire back of the implant contacting the subchondral bone

    Deep Learning Hydrodynamic Forecasting for Flooded Region Assessment in Near-Real-Time (DL Hydro-FRAN)

    Full text link
    Hydrodynamic flood modeling improves hydrologic and hydraulic prediction of storm events. However, the computationally intensive numerical solutions required for high-resolution hydrodynamics have historically prevented their implementation in near-real-time flood forecasting. This study examines whether several Deep Neural Network (DNN) architectures are suitable for optimizing hydrodynamic flood models. Several pluvial flooding events were simulated in a low-relief high-resolution urban environment using a 2D HEC-RAS hydrodynamic model. These simulations were assembled into a training set for the DNNs, which were then used to forecast flooding depths and velocities. The DNNs' forecasts were compared to the hydrodynamic flood models, and showed good agreement, with a median RMSE of around 2 mm for cell flooding depths in the study area. The DNNs also improved forecast computation time significantly, with the DNNs providing forecasts between 34.2 and 72.4 times faster than conventional hydrodynamic models. The study area showed little change between HEC-RAS' Full Momentum Equations and Diffusion Equations, however, important numerical stability considerations were discovered that impact equation selection and DNN architecture configuration. Overall, the results from this study show that DNNs can greatly optimize hydrodynamic flood modeling, and enable near-real-time hydrodynamic flood forecasting.Comment: 21 pages, 8 figure

    Dynamic ductile to brittle transition in a one-dimensional model of viscoplasticity

    Full text link
    We study two closely related, nonlinear models of a viscoplastic solid. These models capture essential features of plasticity over a wide range of strain rates and applied stresses. They exhibit inelastic strain relaxation and steady flow above a well defined yield stress. In this paper, we describe a first step in exploring the implications of these models for theories of fracture and related phenomena. We consider a one dimensional problem of decohesion from a substrate of a membrane that obeys the viscoplastic constitutive equations that we have constructed. We find that, quite generally, when the yield stress becomes smaller than some threshold value, the energy required for steady decohesion becomes a non-monotonic function of the decohesion speed. As a consequence, steady state decohesion at certain speeds becomes unstable. We believe that these results are relevant to understanding the ductile to brittle transition as well as fracture stability.Comment: 10 pages, REVTeX, 12 postscript figure

    Sequential Acquisition of T Cells and Antibodies to Nontyphoidal Salmonella in Malawian Children

    Get PDF
    Background Salmonella Typhimurium (STm) remain a prominent cause of bacteremia in sub-Saharan Africa. Complement-fixing antibodies to STm develop by 2 years of age. We hypothesized that STm-specific CD4+ T cells develop alongside this process. Methods Eighty healthy Malawian children aged 0–60 months were recruited. STm-specific CD4+ T cells producing interferon γ, tumor necrosis factor α, and interleukin 2 were quantified using intracellular cytokine staining. Antibodies to STm were measured by serum bactericidal activity (SBA) assay, and anti-STm immunoglobulin G antibodies by enzyme-linked immunosorbent assay. Results Between 2006 and 2011, STm bacteremias were detected in 449 children <5 years old. STm-specific CD4+ T cells were acquired in infancy, peaked at 14 months, and then declined. STm-specific SBA was detectable in newborns, declined in the first 8 months, and then increased to a peak at age 35 months. Acquisition of SBA correlated with acquisition of anti–STm–lipopolysaccharide (LPS) immunoglobulin G (r = 0.329 [95% confidence interval, .552–.062]; P = .01) but not anti–STm–outer membrane protein or anti–STm-flagellar protein (FliC). Conclusions Acquisition of STm-specific CD4+ T cells in early childhood is consistent with early exposure to STm or cross-reactive protein antigens priming this T-cell development. STm-specific CD4+ T cells seem insufficient to protect against invasive nontyphoidal Salmonella disease, but sequential acquisition of SBA to STm LPS is associated with a decline in its incidence

    Sociology’s missed opportunity: John Stuart-Glennie’s lost theory of the moral revolution, also known as the axial age

    Get PDF
    In 1873, 75 years before Karl Jaspers published his theory of the Axial Age in 1949, unknown to Jaspers and to contemporary scholars today, Scottish folklorist John Stuart Stuart-Glennie elaborated the first fully developed and nuanced theory of what he termed “the Moral Revolution” to characterize the historical shift emerging roughly around 600 BCE in a variety of civilizations, most notably ancient China, India, Judaism, and Greece, as part of a broader critical philosophy of history. He continued to write on the idea over decades in books and articles and also presented his ideas to the fledgling Sociological Society of London in 1905, which were published the following year in the volume Sociological Papers, Volume 2. This article discusses Stuart-Glennie’s ideas on the moral revolution in the context of his philosophy of history, including what he termed “panzooinism”; ideas with implications for contemporary debates in theory, comparative history, and sociology of religion. It shows why he should be acknowledged as the originator of the theory now known as the axial age, and also now be included as a significant sociologist in the movement toward the establishment of sociology

    Incomplete Recovery of Pneumococcal CD4 T Cell Immunity after Initiation of Antiretroviral Therapy in HIV-Infected Malawian Adults

    Get PDF
    HIV-infected African adults are at a considerably increased risk of life-threatening invasive pneumococcal disease (IPD) which persists despite antiretroviral therapy (ART). Defects in naturally acquired pneumococcal-specific T-cell immunity have been identified in HIV-infected adults. We have therefore determined the extent and nature of pneumococcal antigen-specific immune recovery following ART. HIV-infected adults were followed up at 3, 6 and 12 months after initiating ART. Nasopharyngeal swabs were cultured to determine carriage rates. Pneumococcal-specific CD4 T-cell immunity was assessed by IFN-γ ELISpot, proliferation assay, CD154 expression and intracellular cytokine assay. S. pneumoniae colonization was detected in 27% (13/48) of HIV-infected patients prior to ART. The rates remained elevated after 12 months ART, 41% (16/39) (p = 0.17) and significantly higher than in HIV-uninfected individuals (HIVneg 14%(4/29); p = 0.0147). CD4+ T-cell proliferative responses to pneumococcal antigens increased significantly to levels comparable with HIV-negative individuals at 12 months ART (p = 0.0799). However, recovery of the pneumococcal-specific CD154 expression was incomplete (p = 0.0015) as were IFN-γ ELISpot responses (p = 0.0040) and polyfunctional CD4+ T-cell responses (TNF-α, IL-2 and IFN-γ expression) (p = 0.0040) to a pneumolysin-deficient mutant strain. Impaired control of pneumococcal colonisation and incomplete restoration of pneumococcal-specific immunity may explain the persistently higher risk of IPD amongst HIV-infected adults on ART. Whether vaccination and prolonged ART can overcome this immunological defect and reduce the high levels of pneumococcal colonisation requires further evaluation

    Syn‐rift sediment gravity flow deposition on a Late Jurassic fault‐terraced slope, northern North Sea

    Get PDF
    Structurally controlled bathymetry in rifts has a significant influence on sediment routing pathways and depositional architecture of sediment gravity flow deposits. In contrast to rift segments characterized by crustal-scale half-grabens, the tectono-stratigraphic evolution of deep-water rift domains characterised by distributed faulting on narrow fault terraces has received little attention. We use 3D broadband seismic data, calibrated by boreholes, from the Lomre and Uer terraces in the northern North Sea rift to investigate Late Jurassic syn-rift sediment gravity flow systems on fault-terraced slopes. The sediment gravity flow fairways were sourced from hinterland drainages via basin margin deltaic systems on the Horda Platform to the southeast. The deep-water sedimentary systems evolve from initial, widespread submarine channelized lobe complexes, through submarine channels, to incised submarine canyons. This progressive confinement of the sediment gravity flow system was concomitant with progressive localization of strain onto the main terrace-bounding faults. Although the normal fault network on the terraces has local impact on deep-water sediment transport and the architecture of gravity flow deposits, it is the regional basin margin to rift axis gradient that dominantly controls deep-water sediment routing. Furthermore, the gravity flow deposits on the Lomre and Uer terraces were predominantly sourced by rift margin deltaic systems, not from erosion of local uplifted footwall crests, emphasising the significance of hinterland catchments in the development of volumetrically significant deep-water syn-rift depositional systems

    Analysis of the interaction of monoclonal antibodies with surface IgM on neoplastic B-cells

    Get PDF
    In vitro studies identified three Burkitts lymphoma cell lines, Ramos, MUTU-I and Daudi, that were growth inhibited by anti-IgM antibody. However, only Ramos and MUTU-I were sensitive to monoclonal antibodies (mAb) recognizing the Fc region of surface IgM (anti-Fcμ). Experiments using anti-Fcμ mAb (single or non-crossblocking pairs), polyclonal anti-μ Ab, and hyper-crosslinking with a secondary layer of Ab, showed that growth inhibition of B-cell lines was highly dependent on the extent of IgM crosslinking. This was confirmed by using Fab′, F(ab′)2and F(ab′)3derivatives from anti-Fcμ mAb, where increasing valency caused corresponding increases in growth arrest and apoptosis, presumably as a result of more efficient BCR-crosslinking on the cell surface. The ability of a single mAb to induce growth arrest was highly dependent on epitope specificity, with mAb specific for the Fc region (Cμ2–Cμ4 domains) being much more effective than those recognizing the Fab region (anti-L chain, anti-Id and anti-Fdμ, or Cμ1). Only when hyper-crosslinked with polyclonal anti-mouse IgG did the latter result in appreciable growth inhibition. Binding studies showed that these differences in function were not related to differences in the affinity, but probably related to intrinsic crosslinking capacity of mAb. © 1999 Cancer Research Campaig

    Seawater redox variations during the deposition of the Kimmeridge Clay Formation, United Kingdom (Upper Jurassic): evidence from molybdenum isotopes and trace metal ratios

    Get PDF
    The Kimmeridge Clay Formation (KCF) and its equivalents worldwide represent one of the most prolonged periods of organic carbon accumulation of the Mesozoic. In this study, we use the molybdenum (Mo) stable isotope system in conjunction with a range of trace metal paleoredox proxies to assess how seawater redox varied both locally and globally during the deposition of the KCF. Facies with lower organic carbon contents (TOC 1–7 wt %) were deposited under mildly reducing (suboxic) conditions, while organic-rich facies (TOC &gt;7 wt %) accumulated under more strongly reducing (anoxic or euxinic) local conditions. Trace metal abundances are closely linked to TOC content, suggesting that the intensity of reducing conditions varied repeatedly during the deposition of the KCF and may have been related to orbitally controlled climate changes. Long-term variations in ?98/95Mo are associated with the formation of organic-rich intervals and are related to third-order fluctuations in relative sea level. Differences in the mean ?98/95Mo composition of the organic-rich intervals suggest that the global distribution of reducing conditions was more extensive during the deposition of the Pectinatites wheatleyensis and lower Pectinatites hudlestoni zones than during the deposition of the upper Pectinatites hudlestoni and Pectinatites pectinatus zones. The global extent of reducing conditions during the Kimmerigidan was greater than today but was less widespread than during the Toarcian (Early Jurassic) oceanic anoxic event. This study also demonstrates that the Mo isotope system in Jurassic seawater responded to changes in redox conditions in a manner consistent with its behavior in present-day sedimentary environment
    corecore