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Two Novel Psychomotor Tasks in Idiopathic Normal Pressure Hydrocephalus
- Maria A. Rossetti, Irene Piryatinsky, Fayeza S. Ahmed, Petra M. Klinge, Norman R. Relkin, Stephen Salloway, Lisa D. Ravdin, Einat Brenner, Paul F. Malloy, Bonnie E. Levin, Michael Broggi, Rebecca Gavett, James S. Maniscalco, Heather Katzen
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- Journal:
- Journal of the International Neuropsychological Society / Volume 22 / Issue 3 / March 2016
- Published online by Cambridge University Press:
- 28 January 2016, pp. 341-349
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Objective: Idiopathic normal pressure hydrocephalus (INPH) is a neurological disorder presenting with gait, cognitive, and bladder symptoms in the context of ventricular enlargement. Although gait is the primary indicator for treatment candidacy and outcome, additional monitoring tools are needed. Line Tracing Test (LTT) and Serial Dotting Test (SDT), two psychomotor tasks, have been introduced as potential outcome measures but have not been widely studied. This preliminary study examined whether LTT and SDT are sensitive to motor dysfunction in INPH and determined if accuracy and time are important aspects of performance. Methods: Eighty-four INPH subjects and 36 healthy older adults were administered LTT and SDT. Novel error scoring procedures were developed to make scoring practical and efficient; interclass correlation showed good reliability of scoring procedures for both tasks (0.997; p<.001). Results: The INPH group demonstrated slower performance on SDT (p<.001) and made a greater number of errors on both tasks (p<.001). Combined Time/Error scores revealed poorer performance in the INPH group for original-LTT (p<.001), modified-LTT (p≤.001) and SDT (p<.001). Conclusions: These findings indicate LTT and SDT may prove useful for monitoring psychomotor skills in INPH. While completion time reflects impaired processing speed, reduced accuracy may suggest planning and self-monitoring difficulties, aspects of executive functioning known to be compromised in INPH. This is the first study to underscore the importance of performance accuracy in INPH and introduce practical/reliable error scoring for these tasks. Future work will establish reliability and validity of these measures and determine their utility as outcome tools. (JINS, 2016, 22, 341–349)
Pupil constriction evoked in vitro by stimulation of the oculomotor nerve in the turtle (Trachemys scripta elegans)
- JAMES R. DEARWORTH, JR, J.E. BRENNER, J.F. BLAUM, T.E. LITTLEFIELD, D.A. FINK, J.M. ROMANO, M.S. JONES
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- Journal:
- Visual Neuroscience / Volume 26 / Issue 3 / May 2009
- Published online by Cambridge University Press:
- 01 May 2009, pp. 309-318
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The pond turtle (Trachemys scripta elegans) exhibits a notably sluggish pupillary light reflex (PLR), with pupil constriction developing over several minutes following light onset. In the present study, we examined the dynamics of the efferent branch of the reflex in vitro using preparations consisting of either the isolated head or the enucleated eye. Stimulation of the oculomotor nerve (nIII) using 100-Hz current trains resulted in a maximal pupil constriction of 17.4% compared to 27.1% observed in the intact animal in response to light. When current amplitude was systematically increased from 1 to 400 μA, mean response latency decreased from 64 to 45 ms, but this change was not statistically significant. Hill equations fitted to these responses indicated a current threshold of 3.8 μA. Stimulation using single pulses evoked a smaller constriction (3.8%) with response latencies and threshold similar to that obtained using train stimulation. The response evoked by postganglionic stimulation of the ciliary nerve using 100-Hz trains was largely indistinguishable from that of train stimulation of nIII. However, application of single-pulse stimulation postganglionically resulted in smaller pupil constriction at all current levels relative to that of nIII stimulation, suggesting that there is amplification of efferent drive at the ganglion. Time constants for constrictions ranged from 88 to 154 ms with relaxations occurring more slowly at 174–361 ms. These values for timing from in vitro are much faster than the time constant 1.66 min obtained for the light response in the intact animal. The rapid dynamics of pupil constriction observed here suggest that the slow PLR of the turtle observed in vivo is not due to limitations of the efferent pathway. Rather, the sluggish response probably results from photoreceptive mechanisms or central processing.
A continuum model of thermal transpiration
- JAMES R. BIELENBERG, HOWARD BRENNER
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- Journal:
- Journal of Fluid Mechanics / Volume 546 / 10 January 2006
- Published online by Cambridge University Press:
- 21 December 2005, pp. 1-23
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Previous proposed modifications in the respective constitutive forms of the Newtonian deviatoric stress tensor and the no-slip boundary condition imposed upon viscous fluids at solid surfaces, wherein the fluid's mass velocity is replaced by its volume velocity, furnishes a complete continuum-hydrodynamic description of thermal transpiration phenomena occurring in a closed capillary tube filled with a single-component gas or liquid, the former at negligibly small Knudsen numbers. The resulting expression for the steady-state thermomolecular pressure difference $\Delta p$ existing between the two ends of the capillary, the latter maintained at different temperatures, is free of empirical parameters, such as Maxwell's thermal-slip coefficient, upon which current non-continuum theories of the phenomenon are based. The predicted $\Delta p$ (with the pressure highest at the hotter end) is shown to agree well with experimental data for gases in the near-continuum limit of vanishingly small Knudsen number. Also discussed is the experimentally observed lack of dependence of $\Delta p$ upon the physicochemical properties of the capillary walls, an observation which accords with the predictions of our theory. Our proposed volume velocity-based rationalization of the phenomenon of thermal transpiration offers a strictly continuum no-slip alternative to Maxwell's widely-accepted thermal creep explanation thereof, involving slip of the fluid's mass velocity at a non-isothermal surface. The agreement of our theoretical predictions of the thermomolecular pressure difference with experimental data, which is essentially indistinguishable in accuracy from that provided by Maxwell's thermal creep theory, provides further support for the viability of the generic volume velocity-based framework underlying our theory, the latter having recently been used to also rationalize related thermophoretic and diffusiophoretic phenomena in gases, as well as thermal diffusion in liquids.
Dispersion of a ball settling through a quiescent neutrally buoyant suspension
- JAMES R. ABBOTT, ALAN L. GRAHAM, LISA A. MONDY, HOWARD BRENNER
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- Journal:
- Journal of Fluid Mechanics / Volume 361 / 25 April 1998
- Published online by Cambridge University Press:
- 25 April 1998, pp. 309-331
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Individual falling balls were allowed to settle through otherwise quiescent well-mixed suspensions of non-colloidal neutrally buoyant spheres dispersed in a Newtonian liquid. Balls were tracked in three dimensions to determine the variances in their positions about a mean uniform vertical settling path. The primary experimental parameters investigated were the size of the falling ball and the volume fraction and size of the suspended particles. Unlike the horizontal variances, the vertical variances were found to be affected by short-time deterministic behaviour relating to the instantaneous local configurational arrangement of the suspended particles. For sufficiently long intervals between successive observations, the trajectories of the balls were observed to disperse about their mean settling paths in a random manner. This points to the existence of a Gaussian hydrodynamic dispersivity that characterizes the linear temporal growth of the variance in the position of a falling ball. The functional dependence of these horizontal and vertical dispersivities upon the parameters investigated was established.
The dispersivity dyadic was observed to be transversely isotropic with respect to the direction of gravity, with the vertical component at least 25 times larger than the horizontal component. The vertical dispersivity Dˆv (made dimensionless with the diameter of the suspended spheres and the mean settling velocity) was observed to decrease with increasing falling ball diameter, but to decrease less rapidly with concentration than theoretically predicted for very dilute suspensions; moreover, for falling balls equal in size to the suspended spheres, Dˆv increased linearly with increasing volume fraction ϕ of suspended solids.
In addition to the above experiments performed on suspensions of spheres, previously published settling-velocity data on the fall of balls through neutrally buoyant suspensions of rods possessing an aspect ratio of 20 were re-analysed, and vertical dispersivities calculated therefrom. (These data, taken by several of the present investigators in conjunction with other researchers, had only been grossly analysed in prior publications to extract the mean settling velocity of the ball, no attempt having been made at the time to extract dispersivity data too.) The resulting vertical dispersivities, when rendered dimensionless with the rod length and mean settling velocity, showed no statistically significant dependence upon the falling-ball diameter; moreover, all other things being equal, these dispersivities were observed to increase with increasing rod concentration.
Infrared Spectroscopic Characterization of Sulfide Cluster-Derived Ensembles
- James R. Brenner, Levi T. Thompson
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- Journal:
- MRS Online Proceedings Library Archive / Volume 368 / 1994
- Published online by Cambridge University Press:
- 15 February 2011, 203
- Print publication:
- 1994
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The transition metal sulfide clusters (MeCp)2Mo2(μ-SH)2(μ-S)2, (MeCp)2Mo2Co2(μ3-S)2(μ4-S)(CO)4 [MoCoS], and (MeCp)2Mo2 Fe2 (μ3-S)2(CO)8, (MeCp = methylcyclopentadienyl) were used to prepare γ-Al2O3-supported catalysts. For comparison, a series of supported materials was also prepared using conventional incipient wetness impregnation. Infrared spectroscopy of adsorbed species was used to characterize the sites in the clusterderived and conventionally prepared catalysts. Nitric oxide chemisorbed onto the MoCoS/A catalyst was associated initially only with Co sites and then upon gentle heating shifted to the Mo sites, indicating that Co and Mo were in close proximity. In contrast, NO adsorbed onto both Co and Mo sites in the conventionally prepared materials and desorbed independently from these two types of sites. Infrared spectra of adsorbed thiophene and pyridine were similar for the clusterderived and conventionally prepared catalysts. Thiophene reacted at 100 °C to produce both olefinic species. The most abundant products from thiophene HDS were 1-butene, cis-2-butene, and trans-2-butene. Displacement studies showed that thiophene, pyridine, and NO adsorbed to the same site. The most active sites for HDS and HDN contained both Mo and a late transition metal. The HDN product distributions suggested that Mo was selective for C=N bond cleavage while the late transition metals were more active for C=C hydrogenolysis.