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Streamwise velocity and wall-shear stress are acquired simultaneously with a hot-wire and an array of azimuthal/spanwise-spaced skin friction sensors in large-scale pipe and boundary layer flow facilities at high Reynolds numbers. These allow for a correlation analysis on a per-scale basis between the velocity and reference skin friction signals to reveal which velocity-based turbulent motions are stochastically coherent with turbulent skin friction. In the logarithmic region, the wall-attached structures in both the pipe and boundary layers show evidence of self-similarity, and the range of scales over which the self-similarity is observed decreases with an increasing azimuthal/spanwise offset between the velocity and the reference skin friction signals. The present empirical observations support the existence of a self-similar range of wall-attached turbulence, which in turn are used to extend the model of Baars et al. (J. Fluid Mech., vol. 823, p. R2) to include the azimuthal/spanwise trends. Furthermore, the region where the self-similarity is observed correspond with the wall height where the mean momentum equation formally admits a self-similar invariant form, and simultaneously where the mean and variance profiles of the streamwise velocity exhibit logarithmic dependence. The experimental observations suggest that the self-similar wall-attached structures follow an aspect ratio of
in the streamwise, spanwise and wall-normal directions, respectively.
This study presents findings from a first-of-its-kind measurement campaign that includes simultaneous measurements of the full velocity and vorticity vectors in both pipe and boundary layer flows under matched spatial resolution and Reynolds number conditions. Comparison of canonical turbulent flows offers insight into the role(s) played by features that are unique to one or the other. Pipe and zero pressure gradient boundary layer flows are often compared with the goal of elucidating the roles of geometry and a free boundary condition on turbulent wall flows. Prior experimental efforts towards this end have focused primarily on the streamwise component of velocity, while direct numerical simulations are at relatively low Reynolds numbers. In contrast, this study presents experimental measurements of all three components of both velocity and vorticity for friction Reynolds numbers
ranging from 5000 to 10 000. Differences in the two transverse Reynolds normal stresses are shown to exist throughout the log layer and wake layer at Reynolds numbers that exceed those of existing numerical data sets. The turbulence enstrophy profiles are also shown to exhibit differences spanning from the outer edge of the log layer to the outer flow boundary. Skewness and kurtosis profiles of the velocity and vorticity components imply the existence of a ‘quiescent core’ in pipe flow, as described by Kwon et al. (J. Fluid Mech., vol. 751, 2014, pp. 228–254) for channel flow at lower
, and characterize the extent of its influence in the pipe. Observed differences between statistical profiles of velocity and vorticity are then discussed in the context of a structural difference between free-stream intermittency in the boundary layer and ‘quiescent core’ intermittency in the pipe that is detectable to wall distances as small as 5 % of the layer thickness.
Calibration procedures and data are presented for plating thickness measurements of gold, silver, tin, and nickel on copper, brass, and steel basis metals. Both emission and absorption techniques are described, and examples are given of measurements on thicknesses from 10 to 600 millionths of an inch. The use is shown of masking and integrating techniques for curved or unusual shapes.
For the special problem of duplex platings, which have two metals each varying in thickness, the Kα/Kβ absorption ratio and the Lα/Lβ emission ratio are compared with conventional absorption and emission techniques.
Optical and chemical determinations are shown to be less precise as well as considerably slower than X-ray measurements on the same piece. Examples are given of the use of X-ray measurements to study fundamentals of plating processes, such as barrel-plating thickness distributions and variation of thickness across a surface, as well as to study processes such as wear or porosity.
This paper corrects assumptions made by previous authors regarding the magnitude of the error in d-versus-sin2ѱ plots resulting from deviations of the sample surface from the focusing circle. The results show that the effect is not significant for ordinary residual stress measurements. This investigation has also shown that shapes in d-versus- sin2ѱ plots, similar to the sample curvature effect, may exist in samples with large residual stresses. Interpretation of the data should consider the magnitude of the apparent stress, which allows one to distinguish between apparent sample curvature effects and other causes.
Projects that aim to control invasive species often assume that a reduction of the target species will increase native species abundance. However, reports of the responses of native species following exotic species control are relatively rare. We assessed the recovery of the native community in five tidal wetland locations in which we attempted to eradicate the invasive common reed [Phragmites australis (Cav.) Trin. ex Steud.]. We tested whether 3 yr of treatment were able to eradicate Phragmites and promote recovery of the native plant community. After 3 yr of treatment, Phragmites density declined sharply in all treated stands, though it was not eradicated in any of them. Native plant cover increased significantly in treated areas, and community composition, particularly in smaller stands, converged toward that of uninvaded habitat. Thus, even within the relatively short timescale of the treatments and monitoring, significant progress was made toward achieving the goals of controlling Phragmites infestations and promoting native biodiversity. There was a trend toward greater promise for success in smaller stands than larger stands, as has been observed in other studies. A greater emphasis on monitoring whole-community responses to exotic plant control, across a range of conditions, would enhance our ability to plan and design successful management strategies.
Documenting leads and lags in terrestrial records of past climate change is critical to understanding the behavior of Earth’s natural climate system and making reliable predictions of future climate conditions. However, uncertainties of several hundred years in age models make it difficult to distinguish synchronicity and feedbacks in paleo archives. In lakes this is often due to the lack of terrestrial macrofossils in climate-sensitive locations, such as high alpine or dryland settings. The potential of radiocarbon (14C) dating of pollen has long been recognized, but the difficulty of cleanly separating pollen from other kinds of organic carbon has limited its usefulness. Here we report 14C ages on pollen separated by flow cytometry, from a set of closely spaced samples from Mono Lake, California. The accuracy of the pollen ages is tested using well-dated bracketing tephras, the South Mono and North Mono-Inyo tephras. In spite of the purity of the sorted samples, the pollen dates are older than the bounding tephras by ~400 yr, similar to some other pollen-dating studies. While improvements in sample preparation protocols are planned, understanding the geological processes involved in the production, preservation, and deposition of pollen at each site will be critical to developing robust high-resolution age models.
Advective–diffusive transport of passive or reactive scalars in confined environments (e.g. tubes and channels) is often accompanied by diffusive losses/gains through the confining walls. We present analytical solutions for transport of a reactive solute in a tube, whose walls are impermeable to flow but allow for solute diffusion into the surrounding medium. The solute undergoes advection, diffusion and first-order chemical reaction inside the tube, while diffusing and being consumed in the surrounding medium. These solutions represent a leading-order (in the radius-to-length ratio) approximation, which neglects the longitudinal variability of solute concentration in the surrounding medium. A numerical solution of the full problem is used to demonstrate the accuracy of this approximation for a physically relevant range of model parameters. Our analysis indicates that the solute delivery rate can be quantified by a dimensionless parameter, the ratio of a solute’s residence time in a tube to the rate of diffusive losses through the tube’s wall.
We present a critical reanalysis of the black-hole binary coalescences detected during LIGO’s first observing run under different Bayesian prior assumptions. We summarize the main findings of Vitale et al. (2017) and show additional marginalized posterior distributions for some of the binaries’ intrinsic parameters.
These findings were presented at IAU Symposium 338, held on October 16-19, 2017 in Baton Rouge, LA, USA.
Hearing loss can impair effective communication between caregivers and individuals with cognitive impairment. However, hearing loss is not often measured or addressed in care plans for these individuals. The aim of this study is to measure the prevalence of hearing loss and the utilization of hearing aids in a sample of individuals with cognitive impairment in a tertiary care memory clinic.
A retrospective review of 133 charts of individuals >50 years who underwent hearing assessment at a tertiary care memory clinic over a 12-month period (June 2014–June 2015) was undertaken. Using descriptive statistics, the prevalence of hearing loss was determined and associations with demographic variables, relevant medical history, cognitive status, and hearing aid utilization were investigated.
Results indicate that hearing loss is highly prevalent among this sample of cognitively impaired older adults. Sixty percent of the sample had at least a mild hearing loss in the better hearing ear. Among variables examined, age, MMSE, and medical history of diabetes were strongly associated with hearing impairment. Hearing aid utilization increased in concordance with severity of hearing loss, from 9% to 54% of individuals with a mild or moderate/severe hearing loss, respectively.
Hearing loss is highly prevalent among older adults with cognitive impairment. Despite high prevalence of hearing loss, hearing aid utilization remains low. Our study highlights the importance of hearing evaluation and rehabilitation as part of the cognitive assessment and care management plan in this vulnerable population.
We present preliminary results of a long-term spectroscopic monitoring of a magnitude-limited (V < 7.5) sample of OB-supergiants (07.5-B9) aimed at establishing the incidence of co-rotating, large-scale wind structures. In the optical, this can be achieved by detecting rotationally modulated variability in Hα. Dramatic line-profile variations operating on a daily (and in some cases on a hourly) timescale are observed. Firm conclusions regarding the origin of the variability must, however, await a detailed period analysis. There is no clear evidence for a causal link between photospheric and wind activities.
The Southern Hemisphere SHCal04 radiocarbon calibration curve has been updated with the addition of new data sets extending measurements to 2145 cal BP and including the ANSTO Younger Dryas Huon pine data set. Outside the range of measured data, the curve is based upon the ern Hemisphere data sets as presented in IntCal13, with an interhemispheric offset averaging 43 ± 23 yr modeled by an autoregressive process to represent the short-term correlations in the offset.
Methods to measure enteric methane (CH4) emissions from individual ruminants in their production environment are required to validate emission inventories and verify mitigation claims. Estimates of daily methane production (DMP) based on consolidated short-term emission measurements are developing, but method verification is required. Two cattle experiments were undertaken to test the hypothesis that DMP estimated by averaging multiple short-term breath measures of methane emission rate did not differ from DMP measured in respiration chambers (RC). Short-term emission rates were obtained from a GreenFeed Emissions Monitoring (GEM) unit, which measured emission rate while cattle consumed a dispensed supplement. In experiment 1 (Expt. 1), four non-lactating cattle (LW=518 kg) were adapted for 18 days then measured for six consecutive periods. Each period consisted of 2 days of ad libitum intake and GEM emission measurement followed by 1 day in the RC. A prototype GEM unit releasing water as an attractant (GEM water) was also evaluated in Expt. 1. Experiment 2 (Expt. 2) was a larger study based on similar design with 10 cattle (LW=365 kg), adapted for 21 days and GEM measurement was extended to 3 days in each of the six periods. In Expt. 1, there was no difference in DMP estimated by the GEM unit relative to the RC (209.7 v. 215.1 g CH4/day) and no difference between these methods in methane yield (MY, 22.7 v. 23.7 g CH4/kg of dry matter intake, DMI). In Expt. 2, the correlation between GEM and RC measures of DMP and MY were assessed using 95% confidence intervals, with no difference in DMP or MY between methods and high correlations between GEM and RC measures for DMP (r=0.85; 215 v. 198 g CH4/day SEM=3.0) and for MY (r=0.60; 23.8 v. 22.1 g CH4/kg DMI SEM=0.42). When data from both experiments was combined neither DMP nor MY differed between GEM- and RC-based measures (P>0.05). GEM water-based estimates of DMP and MY were lower than RC and GEM (P<0.05). Cattle accessed the GEM water unit with similar frequency to the GEM unit (2.8 v. 3.5 times/day, respectively) but eructation frequency was reduced from 1.31 times/min (GEM) to once every 2.6 min (GEM water). These studies confirm the hypothesis that DMP estimated by averaging multiple short-term breath measures of methane emission rate using GEM does not differ from measures of DMP obtained from RCs. Further, combining many short-term measures of methane production rate during supplement consumption provides an estimate of DMP, which can be usefully applied in estimating MY.
The building of prehospital emergency medical care systems in developing and lower middle-income countries (as defined by the World Bank) is a critical step in those countries’ efforts to reduce unnecessary morbidity and mortality. This case report presents the development of a prehospital care system in Jaffna District, Sri Lanka and provides the results of the system's first year of operations, the likely reasons for the results, and the prospects for sustained operations of the system. The goal of this report is to add to the literature surrounding Emergency Medical Services (EMS) in developing countries by providing insight into the implementation of a prehospital emergency care system in developing and lower middle-income settings.
The level of utilization and the financial performance of the system during its first year of operation were analyzed using data from the Jaffna Regional Director of Health Services (RDHS) Call Center database and information from the implementing organization, Medical Teams International.
The system responded to >2000 emergency calls in its first 11 months of operation. The most utilized ambulance of the system experienced only a US $13.50 loss during the first 12 months of operation. Factors such as up-front support, a systematic approach, and appropriateness contributed to the successful implementation of the Jaffna prehospital EMS system.
The implementation of a prehospital EMS system and its functioning were successful in terms of utility and, in many regards, financial stability. The system's success in development may serve as a potential model for implementing prehospital emergency medical care in other developing and lower middle-income country settings, keeping in mind factors outside of the system that were integral to its developmental success.
ZimmermanJR, BertermannKM, BollingerPJ, WoodyardDR. Prehospital System Development in Jaffna, Sri Lanka. Prehosp Disaster Med. 2013;28(5):1-8.
The following four short essays sprung from separate conversations that Russell McCutcheon and I were having the day after the events of September 11. We found that nearly everyone we spoke to in our field was forced to grapple with these events in the context of their courses, as we ourselves did. These essays represent a small sampling of “a day in the life” of religious studies faculty after the recent tragedies. Rest assured, the CSSR Bulletin will continue to publish material that brings the tools of our discipline to bear upon current affairs as they play out over the coming months.
TERROR AND VIOLENCE THROUGH BUDDHIST LENSES
Stephen C. Berkwitz
Does a course in Buddhism have anything to contribute to an understanding of the tragic events on September 11, 2001 and their aftermath? I think it can, but not just by using Buddhist doctrines of “suffering” and interdependence to “make sense” of what occurred or console those who grieve. There had already been enough sermons delivered by politicians and newscasters for me to offer another one when I stood before my Buddhism class on September 12. Instead, it struck me more pedagogically useful to compare possible “Buddhist” responses to the tragedy to those currently being made in America.
Patterned micro- and nanowires of several compositions in the solution series of BixTey were electrochemically deposited using Electroplate and Lift (E&L) Lithography on Ultrananocrystalline Diamond (UNCD) templates. The composition of the deposited BixTey wires was controlled by mixing saturated solutions of bismuth nitrate and tellurium in various ratios in the electroplating bath. All wires were electroplated via pulsed depositions at -1.4V vs. the saturated calomel electrode (SCE). The morphology and composition of all wires were studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). In general, the BixTey wires were fine-grained and brittle, often fracturing during the liftoff process. By contrast, wires containing less than 5% Te are smooth, and strong enough to support their own weight without a supporting medium for a length of over 100 times the wire diameter.
Fluid flow through a two-dimensional fracture network has been simulated using a discrete fracture model. The computed field-scale permeabilities were then compared to those obtained using an equivalent continuum approach in which the permeability of each grid block is first obtained by performing fine-scale simulations of flow through the fracture network within that region. In the equivalent continuum simulations, different grid-sizes were used, corresponding to N by N grids with N = 10, 40, 100 and 400. The field-scale permeabilities found from the equivalent continuum simulations were generally within 10% of the values found from the discrete fracture simulations. The discrepancies between the two approaches seemed to be randomly related to the grid size, as no convergence was observed as N increased. An interesting finding was that the equivalent continuum approach gave accurate results in cases where the grid block size was clearly smaller than the 'representative elementary volume'.