4,177 research outputs found
The global aerosol-cloud first indirect effect estimated using MODIS, MERRA, and AeroCom
Aerosol-cloud interactions (ACI) represent a significant source of forcing uncertainty in global climate models (GCMs). Estimates of radiative forcing due to ACI in Fifth Assessment Report range from â0.5 to â2.5âWâmâ2. A portion of this uncertainty is related to the first indirect, or Twomey, effect whereby aerosols act as nuclei for cloud droplets to condense upon. At constant liquid water content this increases the number of cloud droplets (Nd) and thus increases the cloud albedo. In this study we use remote-sensing estimates of Nd within stratocumulus regions in combination with state-of-the-art aerosol reanalysis from Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA2) to diagnose how aerosols affect Nd. As in previous studies, Nd is related to sulfate mass through a power law relationship. The slope of the log-log relationship between Nd and SO4 in maritime stratocumulus is found to be 0.31, which is similar to the range of 0.2â0.8 from previous in situ studies and remote-sensing studies in the pristine Southern Ocean. Using preindustrial emissions models, the change in Nd between preindustrial and present day is estimated. Nd is inferred to have more than tripled in some regions. Cloud properties from Moderate Resolution Imaging Spectroradiometer (MODIS) are used to estimate the radiative forcing due to this change in Nd. The Twomey effect operating in isolation is estimated to create a radiative forcing of â0.97â±â0.23âWâmâ2 relative to the preindustrial era
Ultrasonic Wave Dispersion and Attenuation in Fluid Filled Porous Media
The study of ultrasonic wave propagation in granular materials can lead to a better understanding of wave interaction with such materials as uncured cement and concrete. The measured parameters can then be used to investigate the curing process in particular the time required for a given mixture to consolidate. The cohesionless granular materials having loose contact between the constituent grains form a matrix that has negligible shear modulus. Sediment, sandy ground and concrete before solidification can be considered as examples of cohesionless granular materials. The shear and rigidity moduli of these materials can differ greatly from the values obtained by effective medium theories. In particular these differences could affect the ultrasonic wave propagation in such a material. In the case of cohesionless granular material the complete description of mechanical properties requires the consideration of discrete nature of the solid frame and the contact areas between the grains. Therefore wave interaction with such a material should also include the above mentioned effects. The goal of this work is to investigate the ultrasonic wave dispersion and attenuation in cohesionless granular materials the results can be to applied to the monitoring of cement and concrete during the curing process
High-resolution quantitative MRI of multiple sclerosis spinal cord lesions
PURPOSE: Validation of quantitative MR measures for myelin imaging in the postmortem multiple sclerosis spinal cord. METHODS: Four fixed spinal cord samples were imaged first with a 3T clinical MR scanner to identify areas of interest for scanning, and then with a 7T small bore scanner using a multicomponentâdriven equilibrium singleâpulse observation of T(1) and T(2) protocol to produce apparent proton density, T(1), T(2), myelin water, intracellular water, and freeâwater fraction maps. After imaging, the cords were sectioned and stained with histological markers (hematoxylin and eosin, myelin basic protein, and neurofilament protein), which were quantitatively compared with the MR maps. RESULTS: Excellent correspondence was found between highâresolution MR parameter maps and histology, particularly for apparent proton density MRI and myelin basic protein staining. CONCLUSION: Highâresolution quantitative MRI of the spinal cord provides biologically meaningful measures, and could be beneficial to diagnose and track multiple sclerosis lesions in the spinal cord
High-resolution quantitative MRI of multiple sclerosis spinal cord lesions
Purpose: Validation of quantitative MR measuresfor myelin imaging in the postmortem multiple sclerosis spinal cord.
Methods: Four fixed spinal cord samples were imaged first with a 3T clinical MR
scannerto identify areas of interest forscanning, and then with a 7T small bore scanner using a multicomponent-driven equilibrium single-pulse observation of T1 and
T2 protocol to produce apparent proton density, T1, T2, myelin water, intracellular
water, and free-water fraction maps. After imaging, the cords were sectioned and
stained with histological markers (hematoxylin and eosin, myelin basic protein, and
neurofilament protein), which were quantitatively compared with the MR maps.
Results: Excellent correspondence was found between high-resolution MR parameter maps and histology, particularly for apparent proton density MRI and
myelin basic protein staining.
Conclusion: High-resolution quantitative MRI of the spinal cord provides biologically meaningful measures, and could be beneficial to diagnose and track
multiple sclerosis lesions in the spinal cord
A Critical Review of AntiâBullying Programs in North American Elementary Schools
BACKGROUNDBullying behavior is a concern among schoolâaged youth and antiâbullying programs have been implemented in schools throughout North America. Most antiâbullying programs are delivered to adolescent youth because antisocialâaggressive behaviors are typically associated with this developmental stage. This paper is a review of empirically evaluated schoolâbased bullying prevention and intervention programs in North American elementary schools.METHODSWe conducted a systematic, critical review of bullying prevention programming. Data were analyzed to determine the study method, intervention components, measurement of bullying, aggression, or peer victimization, outcomes measured, and results.RESULTSOur review resulted in the identification of 10 interventions aimed at youth in grades Kâ6 enrolled in North American elementary schools. Effective intervention strategies targeted a variety of bullying behaviors using diverse mechanisms and included a schoolâand communityâwide approach. Direct outcomes of the reviewed evaluations were centered on bullying, aggression, and victimization. Indirect outcomes of review evaluations included strategies for bystanders, school achievement, perceived school safety, and knowledge or attitudes about bullying.CONCLUSIONSRecommendations for promising practices in effective bullying intervention programming are offered. The review concludes with suggestions for supporting school health staff and inâservice teachers drawn from the body of research, and offers direction for future study.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151360/1/josh12814_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151360/2/josh12814.pd
Quality of life in Type 1 (insulin-dependent) diabetic patients prior to and after pancreas and kidney transplantation in relation to organ function
Improvement of the quality of life in Type 1 (insulin-dependent) diabetic patients with severe late complications is one of the main goals of pancreas and/or kidney grafting. To assess the influences of these treatment modalities on the different aspects of the quality of life a cross-sectional study in 157 patients was conducted. They were categorized into patients pre-transplant without dialysis (n=29; Group A), pre-transplant under dialysis (n=44; Group B), post-transplant with pancreas and kidney functioning (n=31; Group C), post-transplant with functioning kidney, but insulin therapy (n=29; Group D), post-transplant under dialysis and insulin therapy again (n=15; Group E) and patients after single pancreas transplantation and rejection, with good renal function, but insulin therapy (n=9; Group F). All patients answered a mailed, self-administered questionnaire (217 questions) consisting of a broad spectrum of rehabilitation criteria. The results indicate a better quality of life in Groups C and D as compared to the other groups. In general the scores are highest in C, but without any significant difference to D. Impressive significant differences between C or D and the other groups were found especially in their satisfaction with physical capacity, leisure-time activities or the overall quality of life. The satisfaction with the latter is highest in C (mean±SEM: 4.0±0.2 on a 1 to 5-rating scale; significantly different from A: 3.1±0.1, B: 2.7±0.2 and E: 2.6±0.3; p<0.01), followed by D (3.8±0.2; significantly different from B and E; p<0.01). Group F shows a mean of 3.1±0.4, which is not significantly different from C. The percentages of patients in each group, who are not working: A: 38 %, B: 64 %, C: 74 %, D: 66 %, E: 87 % and F: 78 % indicate that there is no marked improvement in the vocational situation after successful grafting
The Change in Low Cloud Cover in a Warmed Climate Inferred from AIRS, MODIS, and ERA-Interim
Decreases in subtropical low cloud cover (LCC) occur in climate model simulations of global warming. In this study 8-day-averaged observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS) spanning 2002â14 are combined with European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis to compute the dependence of the observed variability of LCC on various predictor variables. Large-scale thermodynamic and dynamic predictors of LCC are selected based on insight from large-eddy simulations (LESs) and observational analysis. It is found that increased estimated inversion strength (EIS) is associated with increased LCC. Drying of the free troposphere is associated with decreased LCC. Decreased LCC accompanies subsidence in regions of relatively low EIS; the opposite is found in regions of high EIS. Finally, it is found that increasing sea surface temperature (SST) leads to a decrease in LCC. These results are in keeping with previous studies of monthly and annual data. Based upon the observed response of LCC to natural variability of the control parameters, the change in LCC is estimated for an idealized warming scenario where SST increases by 1 K and EIS increases by 0.2 K. For this change in EIS and SST the LCC is inferred to decrease by 0.5%â2.7% when the regression models are trained on data observed between 40°S and 40°N and by 1.1%â1.4% when trained on data from trade cumulusâdominated regions. When the data used to train the regression model are restricted to stratocumulus-dominated regions the change in LCC is highly uncertain and varies between â1.6% and +1.4%, depending on the stratocumulus-dominated region used to train the regression model
Rich interaction and feedback supported mammographic training: A trial of an augmented reality approach
The conventional âkeyboard and workstationâ approach allows complex medical image presentation and manipulation during mammographic interpretation. Nevertheless, providing rich interaction and feedback in real time for navigational training or computer assisted detection of disease remains a challenge. Through computer vision and state of the art AR (Augmented Reality) technique, this study proposes an âAR mammographic workstationâ approach which could support workstation-independent rich interaction and real-time feedback. This flexible AR approach explores the feasibility of facilitating various mammographic training scenes via AR as well as its limitations
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