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Author(s): Paul L. Gribble [1]; Stephen H. Scott (corresponding author) A hallmark of the human motor system is its ability to adapt motor patterns for different environmental conditions, such as [...]

This paper presents results from a comprehensive laboratory study of the effects of a fine grained sediment (clay) carrier fluid on the hydraulic gradient of sand-sized sediments (600-2,000 microns) in a 103-mm diameter pipeline. Three sand sizes were evaluated in the pipeline: (1) medium sand (670 microns), coarse sand (1,260 microns), and very coarse sand (2,040 microns). Initial experiments were conducted with water as the carrier fluid. Sand concentrations of 0.05, 0.10, 0.20, and 0.30 by volume ([C.sub.[upsilon]) were evaluated. For each sand concentration, the effect of phosphate clay concentrations on the hydraulic gradient was evaluated. The clay carrier fluids exhibited both Newtonian and non-Newtonian fluid properties. Study results indicate that the hydraulic gradient reduction effect resulting from phosphate clay added to sand and water slurries increases with sand concentration, decreases with particle size, and is maximum within the flow range representing maximum solids stratification with bed contact (2.0-3.0 m/s) in the test pipeline. CE Database keywords: Sediment transport; Pipelines; Hydraulic gradients.

Background Acute kidney injury (AKI) is associated with long-term morbidity and mortality. The effects of AKI on neurocognitive functioning remain unknown. Our objective was to quantify neurocognitive impairment after an episode of AKI. Methods Survivors of AKI were compared with age-matched controls, as well as a convenience sample of patients matched for cardiovascular risk factors with normal kidney function (active control group). Patients with AKI completed two assessments, while the active control group completed one assessment. The assessment included a standardized test: the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and a robotic assessment: Kinarm. Results The cohort consisted of 21 patients with AKI, 16 of whom completed both assessments, and 21 active control patients. The majority of patients with AKI had Kidney Disease: Improving Global Outcomes Stage 3 AKI (86%), 57% received dialysis and 43% recovered to ≤25% of their baseline serum creatinine by their first assessment. Compared with the RBANS, which detected little impairment, the Kinarm categorized patients as impaired in visuomotor (10/21, 48%), attention (10/20, 50%) and executive tasks (11/21, 52%) compared with healthy controls. Additionally, patients with AKI performed significantly worse in attention and visuomotor domains when compared with the active controls. Neurocognitive performance was generally not impacted by the need for dialysis or whether kidney function recovered. Conclusions Robotic technology identified quantifiable neurocognitive impairment in survivors of AKI. Deficits were noted particularly in attention, visuomotor and executive domains. Further investigation into the downstream health consequences of these neurocognitive impairments is warranted. [ABSTRACT FROM AUTHOR]

The authors discuss aspects of the article by Smeets and colleagues which examines how visual feedback is used to guide voluntary movements, citing that online corrections are faster because movement initiation must disengage postural control. They argue that the additional time taken to initiate a simple reaction time task reflects the need to disengage ongoing postural control, which is not necessary for corrective responses during movement.

The accurate measurement of dredge production contributes to the overall efficiency and cost-effectiveness of the dredging process. The use of production measurement systems on pipeline and hopper dredges provides dredging personnel with tools for measuring and monitoring production quantities. The accuracy of these production monitoring systems varies according to the instrumentation used and the knowledge of the sediment and water properties associated with the dredging activity. Each measurement and physical quantity associated with the calculation of dredging quantities has some uncertainty associated with it. The equations for calculating production are functions of multiple variables, each contributing some uncertainty to the final calculation. A general uncertainty analysis is applied to dredge-production measurements and calculations. Equations describing production for hopper and pipeline dredges are reduced to uncertainty expressions using the uncertainty analysis technique. Example calculations are performed to demonstrate the uncertainty potential in production calculations.

Abstract Background Several studies have found correlations between proprioception and visuomotor function during stroke recovery, however two more recent studies have found no correlation. Unfortunately, most of the studies to date have been conducted with clinical assessments of sensation that are observer-based and have poor reliability. We have recently developed new tests to assess position sense and motor function using robotic technology. The present study was conducted to reassess the relationship between position sense and upper limb movement following stroke. Methods We assessed position sense and motor performance of 100 inpatient stroke rehabilitation subjects and 231 non-disabled controls. All subjects completed quantitative assessments of position sense (arm-position matching task) and motor performance (visually-guided reaching task) using the KINARM robotic device. Subjects also completed clinical assessments including handedness, vision, Purdue Pegboard, Chedoke-McMaster Stroke Assessment-Impairment Inventory and Functional Independence Measure (FIM). Neuroimaging documented lesion localization. Fisher’s exact probability tests were used to determine the relationship between performances on the arm-position matching and visually-guided reaching task. Pearson’s correlations were conducted to determine the relationship between robotically measured parameters and clinical assessments. Results Performance by individual subjects on the matching and reaching tasks was statistically independent (Fisher’s test, P Conclusions Our data support the concept that position sense deficits are functionally relevant and point to the importance of assessing proprioceptive and motor impairments independently when planning treatment strategies.

Background: Traditional clinical assessments are used extensively in neurology; however, they can be coarse, which can also make them insensitive to change. Kinarm is a robotic assessment system that has been used for precise assessment of individuals with neurological impairments. However, this precision also leads to the challenge of identifying whether a given change in performance reflects a significant change in an individual's ability or is simply natural variation. Our objective here is to derive confidence intervals and thresholds of significant change for Kinarm Standard Tests™ (KST).Methods: We assessed participants twice within 15 days on all tasks presently available in KST. We determined the 5-95% confidence intervals for each task parameter, and derived thresholds for significant change. We tested for learning effects and corrected for the false discovery rate (FDR) to identify task parameters with significant learning effects. Finally, we calculated intraclass correlation of type ICC [1, 2] (ICC-C) to quantify consistency across assessments.Results: We recruited an average of 56 participants per task. Confidence intervals for Z-Task Scores ranged between 0.61 and 1.55, and the threshold for significant change ranged between 0.87 and 2.19. We determined that 4/11 tasks displayed learning effects that were significant after FDR correction; these 4 tasks primarily tested cognition or cognitive-motor integration. ICC-C values for Z-Task Scores ranged from 0.26 to 0.76.Conclusions: The present results provide statistical bounds on individual performance for KST as well as significant changes across repeated testing. Most measures of performance had good inter-rater reliability. Tasks with a higher cognitive burden seemed to be more susceptible to learning effects, which should be taken into account when interpreting longitudinal assessments of these tasks. [ABSTRACT FROM AUTHOR]

Aims: Patients undergoing coronary artery bypass grafting (CABG) surgery may experience neurological impairment. We examined whether intraoperative regional cerebral oxygen saturation (rSO2) and neurological dysfunction prior to surgery, measured by robotic technology, are important predictors of post-operative performance following CABG surgery. Methods: Adult patients undergoing CABG surgery were recruited for this single-center prospective observational study. Intraoperative rSO2 was captured using the FORESIGHT cerebral oximeter. Neurological assessment was performed pre-operatively and 3 months following surgery using robotic technology and a standardized pen-and-paper assessment. Linear regression models were generated to determine the predictive ability of both intraoperative rSO2 and pre-operative performance on post-operative neurological outcome. Results: Forty patients had complete data available for analysis. Quantified pre-operative performance accounted for a significantly larger amount of variance in post-operative outcome compared to intraoperative rSO2. In particular, pre-operative scoring on a cognitive visuospatial task accounted for 82.2% of variance in post-operative performance (b = 0.937, t(37) = 12.98, p = 1.28e−5). Discussion: Our results suggest that pre-operative performance is a stronger indicator of post-operative neurological outcome than intraoperative rSO2, and should be included as an important variable when elucidating the relationship between cerebral oxygen levels and post-operative neurological impairment. Rigorous neurological assessment prior to surgery can provide valuable information about each individual patient's path to recovery. Conclusion: Using robotic technology, quantified neurological impairment prior to CABG surgery may better predict post-operative neurological outcomes, compared to intraoperative rSO2 values. [ABSTRACT FROM AUTHOR]