Device and method for redirecting electromagnetic signals

DOEpatents

Garcia, Ernest J.

1999-01-01

A device fabricated to redirect electromagnetic signals, the device including a primary driver adapted to provide a predetermined force, a linkage system coupled to the primary driver, a pusher rod rotationally coupled to the linkage system, a flexible rod element attached to the pusher rod and adapted to buckle upon the application of the predetermined force, and a mirror structure attached to the flexible rod element at one end and to the substrate at another end. When the predetermined force buckles the flexible rod element, the mirror structure and the flexible rod element both move to thereby allow a remotely-located electromagnetic signal directed towards the device to be redirected.

Axially shaped channel and integral flow trippers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowther, R.L. Jr.; Johansson, E.B.; Matzner, B.

1992-02-11

This patent describes a fuel assembly. It comprises: fuel rods positioned in spaced array by upper and lower tie-plates, and open ended flow channel surrounding the array for conducting coolant upward between a lower support plate having coolant communicated thereto to an upper support grid having a steam/water outlet communicated thereto. The flow channel surrounding the array for conducting coolant about the fuel rods; the open ended channel having a polygon shaped cross section with the channel constituting a closed conduit with flat side sections connected at corners to form the enclosed conduit; means separate from the channel for connectingmore » the upper and lower tie-plates together and maintaining the fuel rods in spaced array independent of the flow channel, the improvement in the flow channel comprising tapered side walls, the tapered side walls extending from an average thick cross section adjacent the lower support plate to an average thin cross section adjacent the upper core grid whereby the channel is reduced in thickness adjacent the upper core grid to correspond with the reduced pressure adjacent the upper core grid.« less

Characterization of Rod Function Phenotypes Across a Range of Age-Related Macular Degeneration Severities and Subretinal Drusenoid Deposits

PubMed Central

Flynn, Oliver J.; Cukras, Catherine A.; Jeffrey, Brett G.

2018-01-01

Purpose To examine spatial changes in rod-mediated function in relationship to local structural changes across the central retina in eyes with a spectrum of age-related macular degeneration (AMD) disease severity. Methods Participants were categorized into five AMD severity groups based on fundus features. Scotopic thresholds were measured at 14 loci spanning ±18° along the vertical meridian from one eye of each of 42 participants (mean = 71.7 ± 9.9 years). Following a 30% bleach, dark adaptation was measured at eight loci (±12°). Rod intercept time (RIT) was defined from the time to detect a −3.1 log cd/m2 stimulus. RITslope was defined from the linear fit of RIT with decreasing retinal eccentricity. The presence of subretinal drusenoid deposits (SDD), ellipsoid (EZ) band disruption, and drusen at the test loci was evaluated using optical coherence tomography. Results Scotopic thresholds indicated greater rod function loss in the macula, which correlated with increasing AMD group severity. RITslope, which captures the spatial change in the rate of dark adaptation, increased with AMD severity (P < 0.0001). Three rod function phenotypes emerged: RF1, normal rod function; RF2, normal scotopic thresholds but slowed dark adaptation; and RF3, elevated scotopic thresholds with slowed dark adaptation. Dark adaptation was slowed at all loci with SDD or EZ band disruption, and at 32% of loci with no local structural changes. Conclusions Three rod function phenotypes were defined from combined measurement of scotopic threshold and dark adaptation. Spatial changes in dark adaptation across the macula were captured with RITslope, which may be a useful outcome measure for functional studies of AMD. PMID:29847647

Characterization of Rod Function Phenotypes Across a Range of Age-Related Macular Degeneration Severities and Subretinal Drusenoid Deposits.

PubMed

Flynn, Oliver J; Cukras, Catherine A; Jeffrey, Brett G

2018-05-01

To examine spatial changes in rod-mediated function in relationship to local structural changes across the central retina in eyes with a spectrum of age-related macular degeneration (AMD) disease severity. Participants were categorized into five AMD severity groups based on fundus features. Scotopic thresholds were measured at 14 loci spanning ±18° along the vertical meridian from one eye of each of 42 participants (mean = 71.7 ± 9.9 years). Following a 30% bleach, dark adaptation was measured at eight loci (±12°). Rod intercept time (RIT) was defined from the time to detect a -3.1 log cd/m2 stimulus. RITslope was defined from the linear fit of RIT with decreasing retinal eccentricity. The presence of subretinal drusenoid deposits (SDD), ellipsoid (EZ) band disruption, and drusen at the test loci was evaluated using optical coherence tomography. Scotopic thresholds indicated greater rod function loss in the macula, which correlated with increasing AMD group severity. RITslope, which captures the spatial change in the rate of dark adaptation, increased with AMD severity (P < 0.0001). Three rod function phenotypes emerged: RF1, normal rod function; RF2, normal scotopic thresholds but slowed dark adaptation; and RF3, elevated scotopic thresholds with slowed dark adaptation. Dark adaptation was slowed at all loci with SDD or EZ band disruption, and at 32% of loci with no local structural changes. Three rod function phenotypes were defined from combined measurement of scotopic threshold and dark adaptation. Spatial changes in dark adaptation across the macula were captured with RITslope, which may be a useful outcome measure for functional studies of AMD.

Association between retinal thickness measured by spectral-domain optical coherence tomography (OCT) and rod-mediated dark adaptation in non-exudative age-related maculopathy.

PubMed

Clark, Mark E; McGwin, Gerald; Neely, David; Feist, Richard; Mason, John O; Thomley, Martin; White, Milton F; Ozaydin, Bunyamin; Girkin, Christopher A; Owsley, Cynthia

2011-10-01

To examine associations between retinal thickness and rod-mediated dark adaptation in older adults with non-exudative age-related maculopathy (ARM) or normal macular health. A cross-sectional study was conducted with 74 adults ≥ 50 years old from the comprehensive ophthalmology and retina services of an academic eye centre. ARM presence and disease severity in the enrolment eye was defined by the masked grading of stereofundus photos using the Clinical Age-Related Maculopathy grading system. High-definition, spectral-domain optical coherence tomography was used to estimate retinal thickness in a grid of regions in the macula. Rod-mediated dark adaptation, recovery of light sensitivity after a photo-bleach, was measured over a 20-min period for a 500 nm target presented at 5° on the inferior vertical meridian. Main outcomes of interest were retinal thickness in the macula (μm) and parameters of rod-mediated dark adaptation (second slope, third slope, average sensitivity, final sensitivity). In non-exudative disease retinal thickness was decreased in greater disease severity; thinner retina was associated with reductions in average and final rod-mediated sensitivity even after adjustment for age and visual acuity. Impairment in rod-mediated dark adaptation in non-exudative ARM is associated with macular thinning.

Orbital Winch

NASA Technical Reports Server (NTRS)

Hoyt, Robert (Inventor); Slostad, Jeffrey T. (Inventor); Frank, Scott (Inventor); Barnes, Ian M. (Inventor)

2016-01-01

Orbital winch having: lower and upper frames; spool having upper and lower flanges with lower flange attached to lower frame; axial tether guide mounted to upper frame; secondary slewing ring coaxial with spool and rotatably mounted to upper frame, wherein secondary slewing ring's outer surface has gearing; upper tether guide mounted to inner surface of secondary slewing ring; linear translation means having upper end mounted to upper frame and lower end mounted on lower frame; primary slewing ring rotatably mounted within linear translation means allowing translation axially between flanges, wherein primary slewing ring's outer surface has gearing; lower tether guide mounted on primary slewing ring's inner surface; pinion rod having upper end mounted to upper frame and lower end mounted to lower frame, wherein pinion rod's teeth engage primary and secondary slewing rings' outer surface teeth; and tether passing through axial, upper, and lower tether guides and winding around spool.

Apparatus and method for the horizontal, crucible-free growth of silicon sheet crystals

DOEpatents

Ciszek, T.F.

1984-09-12

Apparatus is provided for continuously forming a silicon crystal sheet from a silicon rod in a non-crucible environment. The rod is rotated and fed toward an RF coil in an inert atmosphere so that the upper end of the rod becomes molten and the silicon sheet crystal is pulled therefrom substantially horizontally in a continuous strip. A shorting ring may be provided around the rod to limit the heating to the upper end only. Argon gas can be used to create the inert atmosphere within a suitable closed chamber. By use of this apparatus and method, a substantially defect-free silicon crystal sheet is formed which can be used for micro-circuitry chips or solar cells.

Aerobic Glycolysis Is Essential for Normal Rod Function and Controls Secondary Cone Death in Retinitis Pigmentosa.

PubMed

Petit, Lolita; Ma, Shan; Cipi, Joris; Cheng, Shun-Yun; Zieger, Marina; Hay, Nissim; Punzo, Claudio

2018-05-29

Aerobic glycolysis accounts for ∼80%-90% of glucose used by adult photoreceptors (PRs); yet, the importance of aerobic glycolysis for PR function or survival remains unclear. Here, we further established the role of aerobic glycolysis in murine rod and cone PRs. We show that loss of hexokinase-2 (HK2), a key aerobic glycolysis enzyme, does not affect PR survival or structure but is required for normal rod function. Rods with HK2 loss increase their mitochondrial number, suggesting an adaptation to the inhibition of aerobic glycolysis. In contrast, cones adapt without increased mitochondrial number but require HK2 to adapt to metabolic stress conditions such as those encountered in retinitis pigmentosa, where the loss of rods causes a nutrient shortage in cones. The data support a model where aerobic glycolysis in PRs is not a necessity but rather a metabolic choice that maximizes PR function and adaptability to nutrient stress conditions. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Dopamine D1 receptor activation contributes to light-adapted changes in retinal inhibition to rod bipolar cells.

PubMed

Flood, Michael Daniel; Moore-Dotson, Johnnie M; Eggers, Erika D

2018-05-30

Dopamine modulation of retinal signaling has been shown to be an important part of retinal adaptation to increased background light levels but the role of dopamine modulation of retinal inhibition is not clear. We previously showed that light adaptation causes a large reduction in inhibition to rod bipolar cells, potentially to match the decrease in excitation after rod saturation. In this study we determined how dopamine D1 receptors in the inner retina contribute to this modulation. We found that D1 receptor activation significantly decreased the magnitude of inhibitory light responses from rod bipolar cells, while D1 receptor blockade during light adaptation partially prevented this decline. To determine what mechanisms were involved in the modulation of inhibitory light responses, we measured the effect of D1 receptor activation on spontaneous currents and currents evoked from electrically stimulating amacrine cell inputs to rod bipolar cells. D1 receptor activation decreased the frequency of spontaneous inhibition with no change in event amplitudes, suggesting a presynaptic change in amacrine cell activity in agreement with previous reports that rod bipolar cells lack D1 receptors. Additionally, we found that D1 receptor activation reduced the amplitude of electrically-evoked responses, showing that D1 receptors can modulate amacrine cells directly. Our results suggest that D1 receptor activation can replicate a large portion, but not all of the effects of light adaptation, likely by modulating release from amacrine cells onto rod bipolar cells.

Noninvasive imaging of the human rod photoreceptor mosaic using a confocal adaptive optics scanning ophthalmoscope

PubMed Central

Dubra, Alfredo; Sulai, Yusufu; Norris, Jennifer L.; Cooper, Robert F.; Dubis, Adam M.; Williams, David R.; Carroll, Joseph

2011-01-01

The rod photoreceptors are implicated in a number of devastating retinal diseases. However, routine imaging of these cells has remained elusive, even with the advent of adaptive optics imaging. Here, we present the first in vivo images of the contiguous rod photoreceptor mosaic in nine healthy human subjects. The images were collected with three different confocal adaptive optics scanning ophthalmoscopes at two different institutions, using 680 and 775 nm superluminescent diodes for illumination. Estimates of photoreceptor density and rod:cone ratios in the 5°–15° retinal eccentricity range are consistent with histological findings, confirming our ability to resolve the rod mosaic by averaging multiple registered images, without the need for additional image processing. In one subject, we were able to identify the emergence of the first rods at approximately 190 μm from the foveal center, in agreement with previous histological studies. The rod and cone photoreceptor mosaics appear in focus at different retinal depths, with the rod mosaic best focus (i.e., brightest and sharpest) being at least 10 μm shallower than the cones at retinal eccentricities larger than 8°. This study represents an important step in bringing high-resolution imaging to bear on the study of rod disorders. PMID:21750765

Variation in Rhodopsin Kinase Expression Alters the Dim Flash Response Shut Off and the Light Adaptation in Rod Photoreceptors

PubMed Central

Sakurai, Keisuke; Young, Joyce E.; Kefalov, Vladimir J.; Khani, Shahrokh C.

2011-01-01

Purpose. Rod photoreceptors are exquisitely sensitive light detectors that function in dim light. The timely inactivation of their light responses is critical for the ability of rods to reliably detect and count photons. A key step in the inactivation of the rod transduction is the phosphorylation of the rod visual pigment, rhodopsin, catalyzed by G-protein-dependent receptor kinase 1 (GRK1). Absence of GRK1 greatly prolongs the photoreceptors' light response and enhances their susceptibility to degeneration. This study examined the light responses from mouse rods expressing various levels of GRK1 to evaluate how their function is modulated by rhodopsin inactivation. Methods. Transretinal and single-cell rod electrophysiological recordings were obtained from several strains of mice expressing GRK1 at 0.3- to 3-fold the wild-type levels. The effect of GRK1 expression level on the function of mouse rods was examined in darkness and during background adaptation. Results. Altering the expression of GRK1 from 0.3- to 3-fold that in wild-type rods had little effect on the single photon response amplitude. Notably, increasing the expression level of GRK1 accelerated the dim flash response shut off but had no effect on the saturated response shut off. Additionally, GRK1 excess abolished the acceleration of saturated responses shut off during light adaptation. Conclusions. These results demonstrate that rhodopsin inactivation can modulate the kinetics of recovery from dim light stimulation. More importantly, the ratio of rhodopsin kinase to its modulator recoverin appears critical for the proper adaptation of rods and the acceleration of their response shut off in background light. PMID:21474765

Variation in rhodopsin kinase expression alters the dim flash response shut off and the light adaptation in rod photoreceptors.

PubMed

Sakurai, Keisuke; Young, Joyce E; Kefalov, Vladimir J; Khani, Shahrokh C

2011-08-29

Rod photoreceptors are exquisitely sensitive light detectors that function in dim light. The timely inactivation of their light responses is critical for the ability of rods to reliably detect and count photons. A key step in the inactivation of the rod transduction is the phosphorylation of the rod visual pigment, rhodopsin, catalyzed by G-protein-dependent receptor kinase 1 (GRK1). Absence of GRK1 greatly prolongs the photoreceptors' light response and enhances their susceptibility to degeneration. This study examined the light responses from mouse rods expressing various levels of GRK1 to evaluate how their function is modulated by rhodopsin inactivation. Transretinal and single-cell rod electrophysiological recordings were obtained from several strains of mice expressing GRK1 at 0.3- to 3-fold the wild-type levels. The effect of GRK1 expression level on the function of mouse rods was examined in darkness and during background adaptation. Altering the expression of GRK1 from 0.3- to 3-fold that in wild-type rods had little effect on the single photon response amplitude. Notably, increasing the expression level of GRK1 accelerated the dim flash response shut off but had no effect on the saturated response shut off. Additionally, GRK1 excess abolished the acceleration of saturated responses shut off during light adaptation. These results demonstrate that rhodopsin inactivation can modulate the kinetics of recovery from dim light stimulation. More importantly, the ratio of rhodopsin kinase to its modulator recoverin appears critical for the proper adaptation of rods and the acceleration of their response shut off in background light.

Nuclear reactor control apparatus

DOEpatents

Sridhar, Bettadapur N.

1983-11-01

Nuclear reactor core safety rod release apparatus comprises a control rod having a detent notch in the form of an annular peripheral recess at its upper end, a control rod support tube for raising and lowering the control rod under normal conditions, latches pivotally mounted on the control support tube with free ends thereof normally disposed in the recess in the control rod, and cam means for pivoting the latches out of the recess in the control rod when a scram condition occurs. One embodiment of the invention comprises an additional magnetically-operated latch for releasing the control rod under two different conditions, one involving seismic shock.

Excitation and desensitization of mouse rod photoreceptors in vivo following bright adapting light

PubMed Central

Kang Derwent, Jennifer J; Qtaishat, Nasser M; Pepperberg, David R

2002-01-01

Electroretinographic (ERG) methods were used to determine response properties of mouse rod photoreceptors in vivo following adapting illumination that produced a significant extent of rhodopsin bleaching. Bleaching levels prevailing at ∼10 min and ∼20 min after the adapting exposure were on average 14% and 9%, respectively, based on the analysis of visual cycle retinoids in the eye tissues. Recovery of the rod response to the adapting light was monitored by analysing the ERG a-wave response to a bright probe flash presented at varying times during dark adaptation. A paired-flash procedure, in which the probe flash was presented at defined times after a weak test flash of fixed strength, was used to determine sensitivity of the rod response to the test flash. Recovery of the response to the adapting light was 80% complete at 13.5 ± 3.0 min (mean ± s.d.; n = 7) after adapting light offset. The adapting light caused prolonged desensitization of the weak-flash response derived from paired-flash data. By comparison with results obtained in the absence of the adapting exposure, desensitization determined with a test-probe interval of 80 ms was ∼fourfold after 5 min of dark adaptation and ∼twofold after 20 min. The results indicate, for mouse rods in vivo, that the time scale for recovery of weak-flash sensitivity substantially exceeds that for the recovery of circulating current following significant rhodopsin bleaching. The lingering desensitization may reflect a reduced efficiency of signal transmission in the phototransduction cascade distinct from that due to residual excitation. PMID:12015430

Axially shaped channel and integral flow trippers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowther, R.L.; Johansson, E.B.; Matzner, B.

1988-06-07

A fuel assembly is described comprising fuel rods positioned in spaced array by upper and lower tie-plates, an open ended flow channel surrounding the array for conducting coolant upward between a lower support plate having coolant communicated thereto to an upper support grid having a steam/water outlet communicated thereto. The flow channel surrounds the array for conducting coolant about the fuel rods. The open ended channel has a polygon shaped cross section with the channel constituting a closed conduit with flat side sections connected at corners to form the enclosed conduit; means separate from the channel for connecting the uppermore » and lower tie-plates together and maintaining the fuel rods in spaced array independent of the flow channel. The improvement in the flow channel comprises tapered side walls. The tapered side walls extend from an average thick cross section adjacent the lower support plate to an average thin cross section adjacent the upper core grid whereby the channel is reduced in thickness adjacent the upper core grid to correspond with the reduced pressure adjacent the upper core grid.« less

Truss beam having convex-curved rods, shear web panels, and self-aligning adapters

NASA Technical Reports Server (NTRS)

Fernandez, Ian M. (Inventor)

2013-01-01

A truss beam comprised of a plurality of joined convex-curved rods with self-aligning adapters (SAA) adhesively attached at each end of the truss beam is disclosed. Shear web panels are attached to adjacent pairs of rods, providing buckling resistance for the truss beam. The rods are disposed adjacent to each other, centered around a common longitudinal axis, and oriented so that adjacent rod ends converge to at least one virtual convergence point on the common longitudinal axis, with the rods' curvature designed to increase prevent buckling for the truss beam. Each SAA has longitudinal bores that provide self-aligning of the rods in the SAA, the self-aligning feature enabling creation of strong adhesive bonds between each SAA and the rods. In certain embodiments of the present invention, pultruded unidirectional carbon fiber rods are coupled with carbon fiber shear web panels and metal SAA(s), resulting in a lightweight, low-cost but strong truss beam that is highly resistant to buckling.

Light-Induced Translocation of RGS9-1 and Gβ5L in Mouse Rod Photoreceptors

PubMed Central

Tian, Mei; Zallocchi, Marisa; Wang, Weimin; Chen, Ching-Kang; Palczewski, Krzysztof; Delimont, Duane; Cosgrove, Dominic; Peng, You-Wei

2013-01-01

The transducin GTPase-accelerating protein complex, which determines the photoresponse duration of photoreceptors, is composed of RGS9-1, Gβ5L and R9AP. Here we report that RGS9-1 and Gβ5L change their distribution in rods during light/dark adaptation. Upon prolonged dark adaptation, RGS9-1 and Gβ5L are primarily located in rod inner segments. But very dim-light exposure quickly translocates them to the outer segments. In contrast, their anchor protein R9AP remains in the outer segment at all times. In the dark, Gβ5L's interaction with R9AP decreases significantly and RGS9-1 is phosphorylated at S475 to a significant degree. Dim light exposure leads to quick de-phosphorylation of RGS9-1. Furthermore, after prolonged dark adaptation, RGS9-1 and transducin Gα are located in different cellular compartments. These results suggest a previously unappreciated mechanism by which prolonged dark adaptation leads to increased light sensitivity in rods by dissociating RGS9-1 from R9AP and redistributing it to rod inner segments. PMID:23555598

75 FR 12710 - Airworthiness Directives; Bombardier, Inc., Model DHC-8-400 Series Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-17

... for the main landing gear lock actuator assembly, retraction actuator assembly rod end and piston, and... for the main landing gear lock actuator assembly, retraction actuator assembly rod end and piston, and..., retraction actuator assembly rod end and piston, and the upper bearing in the main landing gear shock strut...

Thin walled channel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowther, R.L.; Johansson, E.B.

1988-06-07

A fuel assembly is described comprising fuel rods positioned in a spaced array by upper and lower tie-plates, an open ended flow channel surrounding the array for conducting coolant upward about the fuel rods, the open ended channel having a polygon shaped cross section with flat side sections connected between the corner sections; means separate from the channel connecting the upper and lower tie-plates together and maintaining the fuel rods in spaced array independent of the flow channel, improvement in the flow channel comprising: four corners having a first thickness; four sides having a second and reduced thickness from themore » corner thickness, the sides welded to the corner sections.« less

Design and finite element analysis of a novel sliding rod microscrew implantation device for mandibular prognathism

PubMed Central

Li, Yanfeng; Lv, Yuan; Lu, Yongjin; Zeng, Pan; Zeng, Xianglong; Guo, Xiaoqian; Han, Weili

2015-01-01

Tooth distalization is an effective approach for mandibular prognathism. Current distalization devices are bulky and clinically complicated. Here, we designed a novel molar distalization device by using a sliding rod and a microscrew and performed a mechanical analysis and finite element model (FEM) analysis of force distribution and displacement of the upper canine, first and second premolar and first molar. A 2D FEM was constructed using the Beam3 element and a 3D FEM was constructed of the mandibular teeth, the periodontal membrane, and the alveolar bones using the UG software. The upper first molar was divided into 12 points on the dental surface to facilitate stress analysis. Force analysis using the ANSYS WORKBECNH revealed that, both horizontally and vertically, the traction force causing distalization of the first molar decreased when the spring coil moved down the L shaped sliding rod. The 3D FEM force analysis revealed distomedial displacement of the upper first molar when the sliding rod microscrew implantation device caused distalization of the molar. These findings support further exploration for the use of the sliding rod microscrew implants as an anchorage for group distal movement of the teeth of patients with mandibular prognathism. PMID:26379860

Fission control system for nuclear reactor

DOEpatents

Conley, G.H.; Estes, G.P.

Control system for nuclear reactor comprises a first set of reactivity modifying rods fixed in a reactor core with their upper ends stepped in height across the core, and a second set of reactivity modifying rods movable vertically within the reactor core and having their lower ends stepped to correspond with the stepped arrangement of the first set of rods, pairs of the rods of the first and second sets being in coaxial alignment.

Variation in sensitivity, absorption and density of the central rod distribution with eccentricity.

PubMed

Tornow, R P; Stilling, R

1998-01-01

To assess the human rod photopigment distribution and sensitivity with high spatial resolution within the central +/-15 degrees and to compare the results of pigment absorption, sensitivity and rod density distribution (number of rods per square degree). Rod photopigment density distribution was measured with imaging densitometry using a modified Rodenstock scanning laser ophthalmoscope. Dark-adapted sensitivity profiles were measured with green stimuli (17' arc diameter, 1 degrees spacing) using a T ubingen manual perimeter. Sensitivity profiles were plotted on a linear scale and rod photopigment optical density distribution profiles were converted to absorption profiles of the rod photopigment layer. Both the absorption profile of the rod photopigment and the linear sensitivity profile for green stimuli show a minimum at the foveal center and increase steeply with eccentricity. The variation with eccentricity corresponds to the rod density distribution. Rod photopigment absorption profiles, retinal sensitivity profiles, and the rod density distribution are linearly related within the central +/-15 degrees. This is in agreement with theoretical considerations. Both methods, imaging retinal densitometry using a scanning laser ophthalmoscope and dark-adapted perimetry with small green stimuli, are useful for assessing the central rod distribution and sensitivity. However, at present, both methods have limitations. Suggestions for improving the reliability of both methods are given.

REACTOR CONTROL

DOEpatents

Fortescue, P.; Nicoll, D.

1962-04-24

A control system employed with a high pressure gas cooled reactor in which a control rod is positioned for upward and downward movement into the neutron field from a position beneath the reactor is described. The control rod is positioned by a coupled piston cylinder releasably coupled to a power drive means and the pressurized coolant is directed against the lower side of the piston. The coolant pressure is offset by a higher fiuid pressure applied to the upper surface of the piston and means are provided for releasing the higher pressure on the upper side of the piston so that the pressure of the coolant drives the piston upwardly, forcing the coupled control rod into the ncutron field of the reactor. (AEC)

Dark-Adapted Chromatic Perimetry for Measuring Rod Visual Fields in Patients with Retinitis Pigmentosa

PubMed Central

Bennett, Lea D.; Klein, Martin; Locke, Kirsten G.; Kiser, Kelly; Birch, David G.

2017-01-01

Purpose Although rod photoreceptors are initially affected in retinitis pigmentosa (RP), the full-field of rod vision is not routinely characterized due to the unavailability of commercial devices detecting rod sensitivity. The purpose of this study was to quantify rod-mediated vision in the peripheral field from patients with RP using a new commercially available perimeter. Methods Participants had one eye dilated and dark-adapted for 45 minutes. A dark-adapted chromatic (DAC) perimeter tested 80 loci 144° horizontally and 72° vertically with cyan stimuli. The number of rod-mediated loci (RML) were analyzed based on normal cone sensitivity (method 1) and associated with full-field electroretinography (ERG) responses by Pearson's r correlation and linear regression. In a second cohort of patients with RP, RML were identified by two-color perimetry (cyan and red; method 2). The two methods for ascribing rod function were compared by Bland-Altman analysis. Results Method 1 RML were correlated with responses to the 0.01 cd.s/m2 flash (P < 0.001), while total sensitivity to the cyan stimulus showed correlation with responses to the 3.0 cd.s/m2 flash (P < 0.0001). Method 2 detected a mean of 10 additional RML compared to method 1. Conclusions Scotopic fields measured with the DAC detected rod sensitivity across the full visual field, even in some patients who had nondetectable rod ERGs. Two-color perimetry is warranted when sensitivity to the cyan stimulus is reduced to ≤20 dB to get a true estimation of rod function. Translational Relevance Many genetic forms of retinitis pigmentosa (RP) are caused by mutations in rod-specific genes. However, treatment trials for patients with RP have relied primarily on photopic (cone-mediated) tests as outcome measures because there are a limited number of available testing methods designed to evaluate rod function. Thus, efficient methods for quantifying rod-mediated vision are needed for the rapidly increasing numbers of clinical trials. PMID:28798898

Development of Rod Function in Term Born and Former Preterm Subjects

PubMed Central

Fulton, Anne B.; Hansen, Ronald M.; Moskowitz, Anne

2009-01-01

Purpose Provide an overview of some of our electroretinographic and psychophysical studies of normal development of rod function and their application to retinopathy of prematurity (ROP). Methods Electroretinographic (ERG) responses to full-field stimuli were recorded from dark adapted subjects. Rod photoreceptor sensitivity, SROD, was calculated by fit of a biochemical model of the activation of phototransduction to the ERG a-wave. Dark adapted psychophysical thresholds for detecting 2° spots in parafoveal (10° eccentric) and peripheral (30° eccentric) retina were measured and the difference between the thresholds, Δ10-30, was examined as a function of age. SROD and Δ10-30 in term born and former preterm subjects were compared. Results In term born infants, (1) the normal developmental increase in SROD changes proportionately with the amount of rod visual pigment, rhodopsin, and (2) rod mediated function in central retina is immature compared to that in peripheral retina. In subjects born prematurely, deficits in rod photoreceptor sensitivity persist long after active ROP has resolved. Maturation of rod mediated thresholds in the central retina is prolonged by mild ROP. Conclusions Characterization of the development of normal rod and rod mediated function provides a foundation for understanding ROP. PMID:19483509

Cone and Rod Loss in Stargardt Disease Revealed by Adaptive Optics Scanning Light Ophthalmoscopy

PubMed Central

Song, Hongxin; Rossi, Ethan A.; Latchney, Lisa; Bessette, Angela; Stone, Edwin; Hunter, Jennifer J.; Williams, David R.; Chung, Mina

2015-01-01

Importance Stargardt disease (STGD1) is characterized by macular atrophy and flecks in the retinal pigment epithelium. The causative ABCA4 gene encodes a protein localizing to photoreceptor outer segments. The pathologic steps by which ABCA4 mutations lead to clinically detectable retinal pigment epithelium changes remain unclear. We investigated early STGD1 using adaptive optics scanning light ophthalmoscopy. Observations Adaptive optics scanning light ophthalmoscopy imaging of 2 brothers with early STGD1 and their unaffected parents was compared with conventional imaging. Cone and rod spacing were increased in both patients (P <.001) with a dark cone appearance. No foveal cones were detected in the older brother. In the younger brother, foveal cones were enlarged with low density (peak cone density, 48.3 × 103 cones/mm2). The ratio of cone to rod spacing was increased in both patients, with greater divergence from normal approaching the foveal center, indicating that cone loss predominates centrally and rod loss increases peripherally. Both parents had normal photoreceptor mosaics. Genetic testing revealed 3 disease-causing mutations. Conclusions and Relevance This study provides in vivo images of rods and cones in STGD1. Although the primary clinical features of STGD1 are retinal pigment epithelial lesions, adaptive optics scanning light ophthalmoscopy reveals increased cone and rod spacing in areas that appear normal in conventional images, suggesting that photoreceptor loss precedes clinically detectable retinal pigment epithelial disease in STGD1. PMID:26247787

Two-phase pressure drop reduction BWR assembly design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dix, G.E.; Crowther, R.L.; Colby, M.J.

1992-05-12

This patent describes a boiling water reactor having discrete bundles of fuel rods confined within channel enclosed fuel assemblies, an improvement to a fuel bundle assembly for placement in the reactor. It comprises a fuel channel having vertically extending walls forming a continuous channel around a fuel assembly volume, the channel being open at the bottom end for engagement to a lower tie plate and open at the upper end for engagement to an upper tie plate; rods for placement within the chamber, each the rod containing fissile material for producing nuclear reaction when in the presence of sufficient moderatedmore » neutron flux; a lower tie plate for supporting the bundle of rods within the channel, the lower tie plate for supporting the bundle of rods within the channel, the lower tie plate joining the bottom of the channel to close the bottom end of the channel, the lower tie plate providing defined apertures for the inflow of water in the channel between the rods for the generating of steam during the nuclear reaction; the plurality of fuel rods extending from the lower tie plate wherein a single phase region of the water in the bundle is defined to an upward portion of the bundle wherein a two phase region of the water and steam in the bundle is defined during nuclear steam generating reaction in the fuel bundle.« less

THERMAL COUPLE FOR MEASURING TEMPERATURE IN A REACTOR

DOEpatents

Kanne, W.

1959-11-24

A thermocouple device for measuring the temperature of a flowing fluid in a conduit within which is positioned a metallic rod is presented. A thermocouple junction is secured to the rod centrally, and thermal insulating support disks having a diameter greater than the rod are secured to the end portions of the rod and adapted to fit transversely in the conduit.

Development of rod function in term born and former preterm subjects.

PubMed

Fulton, Anne B; Hansen, Ronald M; Moskowitz, Anne

2009-06-01

To provide an overview of some of our electroretinographic (ERG) and psychophysical studies of normal development of rod function and their application to retinopathy of prematurity (ROP). ERG responses to full-field stimuli were recorded from dark adapted subjects. Rod photoreceptor sensitivity (SROD) was calculated by fit of a biochemical model of the activation of phototransduction to the ERG a-wave. Dark adapted psychophysical thresholds for detecting 2 degrees spots in parafoveal (10 degrees eccentric) and peripheral (30 degrees eccentric) retina were measured and the difference between the thresholds, Delta10-30, was examined as a function of age. SROD and Delta10-30 in term born and former preterm subjects were compared. In term born infants, (1) the normal developmental increase in SROD changes proportionately with the amount of rod visual pigment, rhodopsin, and (2) rod-mediated function in central retina is immature compared with that in peripheral retina. In subjects born prematurely, deficits in SROD persist long after active ROP has resolved. Maturation of rod-mediated thresholds in the central retina is prolonged by mild ROP. Characterization of the development of normal rod and rod-mediated function provides a foundation for understanding ROP.

Occupancy of the Chromophore Binding Site of Opsin Activates Visual Transduction in Rod Photoreceptors

PubMed Central

Kefalov, Vladimir J.; Carter Cornwall, M.; Crouch, Rosalie K.

1999-01-01

The retinal analogue β-ionone was used to investigate possible physiological effects of the noncovalent interaction between rod opsin and its chromophore 11-cis retinal. Isolated salamander rod photoreceptors were exposed to bright light that bleached a significant fraction of their pigment, were allowed to recover to a steady state, and then were exposed to β-ionone. Our experiments show that in bleach-adapted rods β-ionone causes a decrease in light sensitivity and dark current and an acceleration of the dim flash photoresponse and the rate constants of guanylyl cyclase and cGMP phosphodiesterase. Together, these observations indicate that in bleach-adapted rods β-ionone activates phototransduction in the dark. Control experiments showed no effect of β-ionone in either fully dark-adapted or background light-adapted cells, indicating direct interaction of β-ionone with the free opsin produced by bleaching. We speculate that β-ionone binds specifically in the chromophore pocket of opsin to produce a complex that is more catalytically potent than free opsin alone. We hypothesize that a similar reaction may occur in the intact retina during pigment regeneration. We propose a model of rod pigment regeneration in which binding of 11-cis retinal to opsin leads to activation of the complex accompanied by a decrease in light sensitivity. The subsequent covalent attachment of retinal to opsin completely inactivates opsin and leads to the recovery of sensitivity. Our findings resolve the conflict between biochemical and physiological data concerning the effect of the occupancy of the chromophore binding site on the catalytic potency of opsin. We show that binding of β-ionone to rod opsin produces effects opposite to its previously described effects on cone opsin. We propose that this distinction is due to a fundamental difference in the interaction of rod and cone opsins with retinal, which may have implications for the different physiology of the two types of photoreceptors. PMID:10051522

Depletion of calcium stores regulates calcium influx and signal transmission in rod photoreceptors

PubMed Central

Szikra, Tamas; Cusato, Karen; Thoreson, Wallace B; Barabas, Peter; Bartoletti, Theodore M; Krizaj, David

2008-01-01

Tonic synapses are specialized for sustained calcium entry and transmitter release, allowing them to operate in a graded fashion over a wide dynamic range. We identified a novel plasma membrane calcium entry mechanism that extends the range of rod photoreceptor signalling into light-adapted conditions. The mechanism, which shares molecular and physiological characteristics with store-operated calcium entry (SOCE), is required to maintain baseline [Ca2+]i in rod inner segments and synaptic terminals. Sustained Ca2+ entry into rod cytosol is augmented by store depletion, blocked by La3+ and Gd3+ and suppressed by organic antagonists MRS-1845 and SKF-96365. Store depletion and the subsequent Ca2+ influx directly stimulated exocytosis in terminals of light-adapted rods loaded with the activity-dependent dye FM1–43. Moreover, SOCE blockers suppressed rod-mediated synaptic inputs to horizontal cells without affecting presynaptic voltage-operated Ca2+ entry. Silencing of TRPC1 expression with small interference RNA disrupted SOCE in rods, but had no effect on cone Ca2+ signalling. Rods were immunopositive for TRPC1 whereas cone inner segments immunostained with TRPC6 channel antibodies. Thus, SOCE modulates Ca2+ homeostasis and light-evoked neurotransmission at the rod photoreceptor synapse mediated by TRPC1. PMID:18755743

Light responses in rods of vitamin A-deprived Xenopus.

PubMed

Solessio, Eduardo; Umino, Yumiko; Cameron, David A; Loew, Ellis; Engbretson, Gustav A; Knox, Barry E; Barlow, Robert B

2009-09-01

Accumulation of free opsin by mutations in rhodopsin or insufficiencies in the visual cycle can lead to retinal degeneration. Free opsin activates phototransduction; however, the link between constitutive activation and retinal degeneration is unclear. In this study, the photoresponses of Xenopus rods rendered constitutively active by vitamin A deprivation were examined. Unlike their mammalian counterparts, Xenopus rods do not degenerate. Contrasting phototransduction in vitamin A-deprived Xenopus rods with phototransduction in constitutively active mammalian rods may provide new understanding of the mechanisms that lead to retinal degeneration. The photocurrents of Xenopus tadpole rods were measured with suction electrode recordings, and guanylate cyclase activity was measured with the IBMX (3-isobutyl-1-methylxanthine) jump technique. The amount of rhodopsin in rods was determined by microspectrophotometry. The vitamin A-deprived rod outer segments were 60% to 70% the length and diameter of the rods in age-matched animals. Approximately 90% of its opsin content was in the free or unbound form. Analogous to bleaching adaptation, the photoresponses were desensitized (10- to 20-fold) and faster. Unlike bleaching adaptation, the vitamin A-deprived rods maintained near normal saturating (dark) current densities by developing abnormally high rates of cGMP synthesis. Their rate of cGMP synthesis in the dark (15 seconds(-1)) was twofold greater than the maximum levels attainable by control rods ( approximately 7 seconds(-1)). Preserving circulating current density and response range appears to be an important goal for rod homeostasis. However, the compensatory changes associated with vitamin A deprivation in Xenopus rods come at the high metabolic cost of a 15-fold increase in basal ATP consumption.

Prosthetic Hand For Holding Rods, Tools, And Handles

NASA Technical Reports Server (NTRS)

Belcher, Jewell G., Jr.; Vest, Thomas W.

1995-01-01

Prosthetic hand with quick-grip/quick-release lever broadens range of specialized functions available to lower-arm amputee by providing improved capabilities for gripping rods, tools, handles, and like. Includes two stationary lower fingers opposed by one pivoting upper finger. Lever operates in conjunction with attached bracket.

Adaptations in rod outer segment disc membranes in response to environmental lighting conditions.

PubMed

Rakshit, Tatini; Senapati, Subhadip; Parmar, Vipul M; Sahu, Bhubanananda; Maeda, Akiko; Park, Paul S-H

2017-10-01

The light-sensing rod photoreceptor cell exhibits several adaptations in response to the lighting environment. While adaptations to short-term changes in lighting conditions have been examined in depth, adaptations to long-term changes in lighting conditions are less understood. Atomic force microscopy was used to characterize the structure of rod outer segment disc membranes, the site of photon absorption by the pigment rhodopsin, to better understand how photoreceptor cells respond to long-term lighting changes. Structural properties of the disc membrane changed in response to housing mice in constant dark or light conditions and these adaptive changes required output from the phototransduction cascade initiated by rhodopsin. Among these were changes in the packing density of rhodopsin in the membrane, which was independent of rhodopsin synthesis and specifically affected scotopic visual function as assessed by electroretinography. Studies here support the concept of photostasis, which maintains optimal photoreceptor cell function with implications in retinal degenerations. Copyright © 2017 Elsevier B.V. All rights reserved.

A new mouse model for stationary night blindness with mutant Slc24a1 explains the pathophysiology of the associated human disease

PubMed Central

Vinberg, Frans; Wang, Tian; Molday, Robert S.; Chen, Jeannie; Kefalov, Vladimir J.

2015-01-01

Mutations that affect calcium homeostasis (Ca2+) in rod photoreceptors are linked to retinal degeneration and visual disorders such as retinitis pigmentosa and congenital stationary night blindness (CSNB). It is thought that the concentration of Ca2+ in rod outer segments is controlled by a dynamic balance between influx via cGMP-gated (CNG) channels and extrusion via Na+/Ca2+, K+ exchangers (NCKX1). The extrusion-driven lowering of rod [Ca2+]i following light exposure controls their light adaptation and response termination. Mutant NCKX1 has been linked to autosomal-recessive stationary night blindness. However, whether NCKX1 contributes to light adaptation has not been directly tested and the mechanisms by which human NCKX1 mutations cause night blindness are not understood. Here, we report that the deletion of NCKX1 in mice results in malformed outer segment disks, suppressed expression and function of rod CNG channels and a subsequent 100-fold reduction in rod responses, while preserving normal cone responses. The compensating loss of CNG channel function in the absence of NCKX1-mediated Ca2+ extrusion may prevent toxic Ca2+ buildup and provides an explanation for the stationary nature of the associated disorder in humans. Surprisingly, the lack of NCKX1 did not compromise rod background light adaptation, suggesting additional Ca2+-extruding mechanisms exist in these cells. PMID:26246500

Material test machine for tension-compression tests at high temperature

DOEpatents

Cioletti, Olisse C.

1988-01-01

Apparatus providing a device for testing the properties of material specimens at high temperatures and pressures in controlled water chemistries includes, inter alia, an autoclave housing the specimen which is being tested. The specimen is connected to a pull rod which couples out of the autoclave to an external assembly which includes one or more transducers, a force balance chamber and a piston type actuator. The pull rod feeds through the force balance chamber and is compensated thereby for the pressure conditions existing within the autoclave and tending to eject the pull rod therefrom. The upper end of the push rod is connected to the actuator through elements containing a transducer comprising a linear variable differential transformer (LVDT). The housing and coil assembly of the LVDT is coupled to a tube which runs through a central bore of the pull rod into the autoclave where it is connected to one side of the specimen. The movable core of the LVDT is coupled to a stem which runs through the tube where it is then connected to the other side of the specimen through a coupling member. A transducer in the form of a load cell including one or more strain gages is located on a necked-down portion of the upper part of the pull rod intermediate the LVDT and force balance chamber.

LOGIC CIRCUIT

DOEpatents

Strong, G.H.; Faught, M.L.

1963-12-24

A device for safety rod counting in a nuclear reactor is described. A Wheatstone bridge circuit is adapted to prevent de-energizing the hopper coils of a ball backup system if safety rods, sufficient in total control effect, properly enter the reactor core to effect shut down. A plurality of resistances form one arm of the bridge, each resistance being associated with a particular safety rod and weighted in value according to the control effect of the particular safety rod. Switching means are used to switch each of the resistances in and out of the bridge circuit responsive to the presence of a particular safety rod in its effective position in the reactor core and responsive to the attainment of a predetermined velocity by a particular safety rod enroute to its effective position. The bridge is unbalanced in one direction during normal reactor operation prior to the generation of a scram signal and the switching means and resistances are adapted to unbalance the bridge in the opposite direction if the safety rods produce a predetermined amount of control effect in response to the scram signal. The bridge unbalance reversal is then utilized to prevent the actuation of the ball backup system, or, conversely, a failure of the safety rods to produce the predetermined effect produces no unbalance reversal and the ball backup system is actuated. (AEC)

20. VIEW SOUTHEAST OF UPPER LEVEL (LUMBER STORAGE) IN EAST ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

20. VIEW SOUTHEAST OF UPPER LEVEL (LUMBER STORAGE) IN EAST BUILDING SHOWING BUILDING FRAMEWORK, IRON HANGING RODS, AND CEDAR PLANKS BEING SEASONED FOR BOAT CONSTRUCTION. - Lowell's Boat Shop, 459 Main Street, Amesbury, Essex County, MA

Effect of 11-Cis 13-Demethylretinal on Phototransduction in Bleach-Adapted Rod and Cone Photoreceptors

PubMed Central

Corson, D.Wesley; Kefalov, Vladimir J.; Cornwall, M. Carter; Crouch, Rosalie K.

2000-01-01

We used 11-cis 13-demethylretinal to examine the physiological consequences of retinal's noncovalent interaction with opsin in intact rod and cone photoreceptors during visual pigment regeneration. 11-Cis 13-demethylretinal is an analog of 11-cis retinal in which the 13 position methyl group has been removed. Biochemical experiments have shown that it is capable of binding in the chromophore pocket of opsin, forming a Schiff-base linkage with the protein to produce a pigment, but at a much slower rate than the native 11-cis retinal (Nelson, R., J. Kim deReil, and A. Kropf. 1970. Proc. Nat. Acad. Sci. USA. 66:531–538). Experimentally, this slow rate of pigment formation should allow separate physiological examination of the effects of the initial binding of retinal in the pocket and the subsequent formation of the protonated Schiff-base linkage. Currents from solitary rods and cones from the tiger salamander were recorded in darkness before and after bleaching and then after exposure to 11-cis 13-demethylretinal. In bleach-adapted rods, 11-cis 13-demethylretinal caused transient activation of phototransduction, as evidenced by a decrease of the dark current and sensitivity, acceleration of the dim flash responses, and activation of cGMP phosphodiesterase and guanylyl cyclase. The steady state of phototransduction activity was still higher than that of the bleach-adapted rod. In contrast, exposure of bleach-adapted cones to 11-cis 13-demethylretinal resulted in an immediate deactivation of transduction as measured by the same parameters. These results extend the validity of a model for the effects of the noncovalent binding of a retinoid in the chromophore pockets of rod and cone opsins to analogs capable of forming a Schiff-base and imply that the noncovalent binding by itself may play a role for the dark adaptation of photoreceptors. PMID:10919871

Light adaptation alters the source of inhibition to the mouse retinal OFF pathway

PubMed Central

Mazade, Reece E.

2013-01-01

Sensory systems must avoid saturation to encode a wide range of stimulus intensities. One way the retina accomplishes this is by using both dim-light-sensing rod and bright-light-sensing cone photoreceptor circuits. OFF cone bipolar cells are a key point in this process, as they receive both excitatory input from cones and inhibitory input from AII amacrine cells via the rod pathway. However, in addition to AII amacrine cell input, other inhibitory inputs from cone pathways also modulate OFF cone bipolar cell light signals. It is unknown how these inhibitory inputs to OFF cone bipolar cells change when switching between rod and cone pathways or whether all OFF cone bipolar cells receive rod pathway input. We found that one group of OFF cone bipolar cells (types 1, 2, and 4) receive rod-mediated inhibitory inputs that likely come from the rod-AII amacrine cell pathway, while another group of OFF cone bipolar cells (type 3) do not. In both cases, dark-adapted rod-dominant light responses showed a significant contribution of glycinergic inhibition, which decreased with light adaptation and was, surprisingly, compensated by an increase in GABAergic inhibition. As GABAergic input has distinct timing and spatial spread from glycinergic input, a shift from glycinergic to GABAergic inhibition could significantly alter OFF cone bipolar cell signaling to downstream OFF ganglion cells. Larger GABAergic input could reflect an adjustment of OFF bipolar cell spatial inhibition, which may be one mechanism that contributes to retinal spatial sensitivity in the light. PMID:23926034

Increased visual sensitivity following periods of dim illumination.

PubMed

McKeown, Alex S; Kraft, Timothy W; Loop, Michael S

2015-02-19

We measured changes in the sensitivity of the human rod pathway by testing visual reaction times before and after light adaptation. We targeted a specific range of conditioning light intensities to see if a physiological adaptation recently discovered in mouse rods is observable at the perceptual level in humans. We also measured the noise spectrum of single mouse rods due to the importance of the signal-to-noise ratio in rod to rod bipolar cell signal transfer. Using the well-defined relationship between stimulus intensity and reaction time (Piéron's law), we measured the reaction times of eight human subjects (ages 24-66) to scotopic test flashes of a single intensity before and after the presentation of a 3-minute background. We also made recordings from single mouse rods and processed the cellular noise spectrum before and after similar conditioning exposures. Subject reaction times to a fixed-strength stimulus were fastest 5 seconds after conditioning background exposure (79% ± 1% of the preconditioning mean, in darkness) and were significantly faster for the first 12 seconds after background exposure (P < 0.01). During the period of increased rod sensitivity, the continuous noise spectrum of individual mouse rods was not significantly increased. A decrease in human reaction times to a dim flash after conditioning background exposure may originate in rod photoreceptors through a transient increase in the sensitivity of the phototransduction cascade. There is no accompanying increase in rod cellular noise, allowing for reliable transmission of larger rod signals after conditioning exposures and the observed increase in perceptual sensitivity. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

Mechanisms that limit the light stimulus frequency following through the APB sensitive and insensitive rod Off-pathways

PubMed Central

Bai, Xia; Zhu, Junling; Yang, Jinnan; Savoie, Brian T.; Wang, Guo-Yong

2009-01-01

In the retina, rod signal pathways process scotopic visual information. Light decrements are mediated by two distinct groups of rod pathways in the dark adapted retina that can be differentiated on the basis of their sensitivity to the glutamate agonist DL-2-amino-4-phosphonobutyric acid (APB). We have found that the APB sensitive and insensitive rod Off-pathways signal different light decrement information: the APB sensitive rod Off-pathway conveys slow and low frequency light signals, whereas the APB insensitive rod Off-pathways mediate fast and high frequency light signals (Wang, 2006). However, the mechanisms which limit the frequency following through the APB sensitive and insensitive rod Off-pathways remain unknown. In the current study, whole-cell patch-clamp recordings were made from ganglion cells in dark and light adapted mouse retina to identify the mechanisms that limit the frequency following through the APB sensitive and insensitive rod Off-pathways. The results showed that the sites from AII amacrine cells to Off cone bipolar cells are the major mechanisms that limit the frequency following through the APB sensitive rod Off-pathway. In the APB insensitive rod Off-pathways, rods themselves limited the frequency following through these pathways. Moreover, ganglion cells were able to follow higher frequencies under photopic conditions than under scotopic conditions. The Off responses followed lower frequencies than On responses under photopic conditions. This finding was observed in cells that yielded On or Off responses only as well as in On-Off cells. PMID:19406212

Evaluation of the 3D Finite Element Method Using a Tantalum Rod for Osteonecrosis of the Femoral Head

PubMed Central

Shi, Jingsheng; Chen, Jie; Wu, Jianguo; Chen, Feiyan; Huang, Gangyong; Wang, Zhan; Zhao, Guanglei; Wei, Yibing; Wang, Siqun

2014-01-01

Background The aim of this study was to contrast the collapse values of the postoperative weight-bearing areas of different tantalum rod implant positions, fibula implantation, and core decompression model and to investigate the advantages and disadvantages of tantalum rod implantation in different ranges of osteonecrosis in comparison with other methods. Material/Methods The 3D finite element method was used to establish the 3D finite element model of normal upper femur, 3D finite element model after tantalum rod implantation into different positions of the upper femur in different osteonecrosis ranges, and other 3D finite element models for simulating fibula implant and core decompression. Results The collapse values in the weight-bearing area of the femoral head of the tantalum rod implant model inside the osteonecrosis area, implant model in the middle of the osteonecrosis area, fibula implant model, and shortening implant model exhibited no statistically significant differences (p>0.05) when the osteonecrosis range was small (60°). The stress values on the artificial bone surface for the tantalum rod implant model inside the osteonecrosis area and the shortening implant model exhibited statistical significance (p<0.01). Conclusions Tantalum rod implantation into the osteonecrosis area can reduce the collapse values in the weight-bearing area when osteonecrosis of the femoral head (ONFH) was in a certain range, thereby obtaining better clinical effects. When ONFH was in a large range (120°), the tantalum rod implantation inside the osteonecrosis area, shortening implant or fibula implant can reduce the collapse values of the femoral head, as assessed by other methods. PMID:25479830

77 FR 36137 - Airworthiness Directives; AGUSTA S.p.A. Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-18

... the upper end of collective control rod C2 to torque tube C3 is properly installed. This AD is... prevent separation of the collective control rod from the torque tube, loss of control of the collective... helicopters because the production quality control procedures did not require recording the applied torque on...

Landing gear energy absorption system

NASA Technical Reports Server (NTRS)

Hansen, Christopher P. (Inventor)

1994-01-01

A landing pad system is described for absorbing horizontal and vertical impact forces upon engagement with a landing surface where circumferentially arranged landing struts respectively have a clevis which receives a slidable rod member and where the upper portion of a slidable rod member is coupled to the clevis by friction washers which are force fit onto the rod member to provide for controlled constant force energy absorption when the rod member moves relative to the clevis. The lower end of the friction rod is pivotally attached by a ball and socket to a support plate where the support plate is arranged to slide in a transverse direction relative to a housing which contains an energy absorption material for absorbing energy in a transverse direction.

Biomechanical risk factors for proximal junctional kyphosis: a detailed numerical analysis of surgical instrumentation variables.

PubMed

Cammarata, Marco; Aubin, Carl-Éric; Wang, Xiaoyu; Mac-Thiong, Jean-Marc

2014-04-15

Biomechanical analysis of proximal junctional kyphosis (PJK) through computer simulations and sensitivity analysis. To gain biomechanical knowledge on the risk of PJK and find surgical solutions to reduce the risks. PJK is a pathological kyphotic deformity adjacent to the instrumentation. Clinical studies have documented its risk factors, but still little is known on how it is correlated with various individual instrumentation variables. Biomechanical spine models of 6 patients with adult scoliosis were developed, validated, and then used to perform 576 simulations, varying the proximal dissection procedure, the implant type at the upper instrumented vertebra, the sagittal rod curvature, and the proximal diameter of the proximal transition rods. Four biomechanical indices--the proximal junctional kyphotic angle, thoracic kyphosis, proximal flexion force, and proximal flexion moment--were assessed. The bilateral complete facetectomy, the posterior ligaments resection, and the combination of both increased the proximal junctional kyphotic angle (respectively, by 10%, 28% and 53%) and the proximal flexion force (4%, 12%, and 22%) and moment (16%, 44%, and 83%). Compared with pedicle screws at upper instrumented vertebra, proximal transverse process hooks reduced the 3 biomechanical indices by approximately 26%. The use of proximal transition rods with reduced proximal diameter from 5.5 mm to 4 mm decreased the proximal junctional kyphotic angle (by 6%) and the proximal flexion force (4%) and moment (8%). The increase of the sagittal rod curvature from 10° to 20°, 30°, and 40° increased the proximal junctional kyphotic angle (by 6%, 13%, and 19%) and the proximal flexion force (3%, 7%, and 10%) and moment (9%, 18%, and 27%). Preserving more posterior proximal intervertebral elements, the use of transition rods and transverse process hooks at upper instrumented vertebra, and reducing the global sagittal rod curvature each decreased the 4 biomechanical indices that may be involved in PJK. N/A.

Adaptation of cone pigments found in green rods for scotopic vision through a single amino acid mutation

PubMed Central

Kojima, Keiichi; Matsutani, Yuki; Yamashita, Takahiro; Yanagawa, Masataka; Imamoto, Yasushi; Yamano, Yumiko; Wada, Akimori; Hisatomi, Osamu; Nishikawa, Kanto; Sakurai, Keisuke; Shichida, Yoshinori

2017-01-01

Most vertebrate retinas contain a single type of rod for scotopic vision and multiple types of cones for photopic and color vision. The retinas of certain amphibian species uniquely contain two types of rods: red rods, which express rhodopsin, and green rods, which express a blue-sensitive cone pigment (M1/SWS2 group). Spontaneous activation of rhodopsin induced by thermal isomerization of the retinal chromophore has been suggested to contribute to the rod’s background noise, which limits the visual threshold for scotopic vision. Therefore, rhodopsin must exhibit low thermal isomerization rate compared with cone visual pigments to adapt to scotopic condition. In this study, we determined whether amphibian blue-sensitive cone pigments in green rods exhibit low thermal isomerization rates to act as rhodopsin-like pigments for scotopic vision. Anura blue-sensitive cone pigments exhibit low thermal isomerization rates similar to rhodopsin, whereas Urodela pigments exhibit high rates like other vertebrate cone pigments present in cones. Furthermore, by mutational analysis, we identified a key amino acid residue, Thr47, that is responsible for the low thermal isomerization rates of Anura blue-sensitive cone pigments. These results strongly suggest that, through this mutation, anurans acquired special blue-sensitive cone pigments in their green rods, which could form the molecular basis for scotopic color vision with normal red rods containing green-sensitive rhodopsin. PMID:28484015

High-Powered, Ultrasonically Assisted Thermal Stir Welding

NASA Technical Reports Server (NTRS)

Ding, Robert

2013-01-01

This method is a solid-state weld process capable of joining metallic alloys without melting. The weld workpieces to be joined by thermal stir welding (TSW) are drawn, by heavy forces, between containment plates past the TSW stir tool that then causes joining of the weld workpiece. TSW is similar to friction stir welding (FSW) in that material is heated into a plastic state (not melted) and stirred using a stir rod. The FSW pin tool is an integrated geometrical structure consisting of a large-diameter shoulder, and a smaller-diameter stir pin protruding from the shoulder. When the pin is plunged into a weld workpiece, the shoulder spins on the surface of the weld workpiece, thus inducing frictional heat into the part. The pin stirs the fraying surfaces of the weld joint, thus joining the weld workpiece into one structure. The shoulder and stir pin of the FSW pin tool must rotate together at a desired rotational speed. The induced frictional energy control and stir pin control of the pin tool cannot be de-coupled. The two work as one integrated unit. TSW, on the other hand, de-couples the heating and stirring of FSW, and allows for independent control of each process element. A uniquely designed induction coil heats the weld workpiece to a desired temperature, and once heated, the part moves into a stir rod whose RPM is also independently controlled. As the weld workpiece moves into the stir rod, the piece is positioned, or sandwiched, between upper and lower containment plates. The plate squeezes together, thus compressing the upper and lower surfaces of the weld workpiece. This compressive force, also called consolidation force, consolidates the plastic material within the weld nugget material as it is being stirred by the stir rod. The stir rod is positioned through the center of the top containment plate and protrudes midway through the opposite lower containment plate where it is mechanically captured. The upper and lower containment plates are separated by a distance equal to the thickness of the material being welded. The TSW process can be significantly improved by reducing the draw forces. This can be achieved by reducing the friction forces between the weld workpieces and the containment plates. High-power ultrasonic (HPU) vibrations of the containment plates achieve friction reduction in the TSW process. Furthermore, integration of the HPU energy into the TSW stir rod can increase tool life of the stir rod, and can reduce shear forces to which the stir rod is subjected during the welding process. TSW has been used to successfully join 0.500-in (˜13-mm) thick commercially pure (CP) titanium, titanium 6AL- 4V, and titanium 6AL-4V ELI in weld joint lengths up to 9 ft (˜2.75-m) long. In addition, the TSW process was used to fabricate a sub-scale hexagonally shaped gun turret component for the U.S. Navy. The turret is comprised of six 0.5000-in (˜13-mm) thick angled welds. Each angled weld joint was prepared by machining the mating surfaces to 120deg. The angled weld joint was then fixtured using an upper and lower containment plate of the same geometry of the angled weld joint. The weld joint was then stirred by the stir rod as it and the upper and lower containment plates traverse through the angled joint prep.

Control rod driveline and grapple

DOEpatents

Germer, John H.

1987-01-01

A control rod driveline and grapple is disclosed for placement between a control rod drive and a nuclear reactor control rod containing poison for parasitic neutron absorption required for reactor shutdown. The control rod is provided with an enlarged cylindrical handle which terminates in an upwardly extending rod to provide a grapple point for the driveline. The grapple mechanism includes a tension rod which receives the upwardly extending handle and is provided with a lower annular flange. A plurality of preferably six grapple segments surround and grip the control rod handle. Each grapple rod segment grips the flange on the tension rod at an interior upper annular indentation, bears against the enlarged cylindrical handle at an intermediate annulus and captures the upwardly flaring frustum shaped handle at a lower and complementary female segment. The tension rods and grapple segments are surrounded by and encased within a cylinder. The cylinder terminates immediately and outward extending annulus at the lower portion of the grapple segments. Excursion of the tension rod relative to the encasing cylinder causes rod release at the handle by permitting the grapple segments to pivot outwardly and about the annulus on the tension rod so as to open the lower defined frustum shaped annulus and drop the rod. Relative movement between the tension rod and cylinder can occur either due to electromagnetic release of the tension rod within defined limits of travel or differential thermal expansion as between the tension rod and cylinder as where the reactor exceeds design thermal limits.

Automatic thermocouple positioner for use in vacuum furnaces

DOEpatents

Mee, D.K.; Stephens, A.E.

1980-06-06

The invention is a simple and reliable mechanical arrangement for automatically positioning a thermocouple-carrying rod in a vacuum-furnace assembly of the kind including a casing, a furnace mounted in the casing, and a charge-containing crucible mounted in the furnace for vertical movement between a lower (loading) position and a raised (charge-melting) position. In a preferred embodiment, a welded-diaphragm metal bellows is mounted above the furnace, the upper end of the bellows being fixed against movement and the lower end of the bellows being affixed to support means for a thermocouple-carrying rod which is vertically oriented and extends freely through the furnace lid toward the mouth of the crucible. The support means and rod are mounted for relative vertical movement. Before pumpdown of the furnace, the differential pressure acting on the bellows causes it to contract and lift the thermocouple rod to a position where it will not be contacted by the crucible charge when the crucible is elevated to its raised position. During pumpdown, the bellows expands downward, lowering the thermocouple rod and its support. The bellows expands downward beyond a point where downward movement of the thermocouple rod is arrested by contact with the crucible charge and to a point where the upper end of the thermocouple extends well above the thermocouple support. During subsequent melting of the charge, the thermocouple sinks into the melt to provide an accurate measurement of melt temperatures.

Automatic thermocouple positioner for use in vacuum furnaces

DOEpatents

Mee, David K.; Stephens, Albert E.

1981-01-01

The invention is a simple and reliable mechanical arrangement for automatically positioning a thermocouple-carrying rod in a vacuum-furnace assembly of the kind including a casing, a furnace mounted in the casing, and a charge-containing crucible mounted in the furnace for vertical movement between a lower (loading) position and a raised (charge-melting) position. In a preferred embodiment, a welded-diaphragm metal bellows is mounted above the furnace, the upper end of the bellows being fixed against movement and the lower end of the bellows being affixed to support means for a thermocouple-carrying rod which is vertically oriented and extends freely through the furnace lid toward the mouth of the crucible. The support means and rod are mounted for relative vertical movement. Before pumpdown of the furnace, the differential pressure acting on the bellows causes it to contract and lift the thermocouple rod to a position where it will not be contacted by the crucible charge when the crucible is elevated to its raised position. During pumpdown, the bellows expands downward, lowering the thermocouple rod and its support. The bellows expands downward beyond a point where downward movement of the thermocouple rod is arrested by contact with the crucible charge and to a point where the upper end of the thermocouple extends well above the thermocouple support. During subsequent melting of the charge, the thermocouple sinks into the melt to provide an accurate measurement of melt temperatures.

Psychophysical Measurement of Rod and Cone Thresholds in Stargardt Disease with Full-Field Stimuli

PubMed Central

Collison, Frederick T.; Fishman, Gerald A.; McAnany, J. Jason; Zernant, Jana; Allikmets, Rando

2014-01-01

Purpose To investigate psychophysical thresholds in Stargardt disease with the full-field stimulus test (FST). Methods Visual acuity (VA), spectral-domain optical coherence tomography (SD-OCT), full-field electroretinogram (ERG), and FST measurements were made in one eye of 24 patients with Stargardt disease. Dark-adapted rod FST thresholds were measured with short-wavelength stimuli, and cone FST thresholds were obtained from the cone plateau phase of dark adaptation using long-wavelength stimuli. Correlation coefficients were calculated for FST thresholds versus macular thickness, VA and ERG amplitudes. Results Stargardt patient FST cone thresholds correlated significantly with VA, macular thickness, and ERG cone-response amplitudes (all P<0.01). The patients’ FST rod thresholds correlated with ERG rod-response amplitudes (P<0.01), but not macular thickness (P=0.05). All Stargardt disease patients with flecks confined to the macula and most of the patients with flecks extending outside of the macula had normal FST thresholds. All patients with extramacular atrophic changes had elevated FST cone thresholds and most had elevated FST rod thresholds. Conclusion FST rod and cone threshold elevation in Stargardt disease patients correlated well with measures of structure and function, as well as ophthalmoscopic retinal appearance. FST appears to be a useful tool for assessing rod and cone function in Stargardt disease. PMID:24695063

The Effects of Diabetic Retinopathy and Pan-Retinal Photocoagulation on Photoreceptor Cell Function as Assessed by Dark Adaptometry

PubMed Central

Bavinger, J. Clay; Dunbar, Grace E.; Stem, Maxwell S.; Blachley, Taylor S.; Kwark, Leon; Farsiu, Sina; Jackson, Gregory R.; Gardner, Thomas W.

2016-01-01

Purpose The pathophysiology of vision loss in persons with diabetic retinopathy (DR) is complex and incompletely defined. We hypothesized that retinal pigment epithelium (RPE) and rod and cone photoreceptor dysfunction, as measured by dark adaptometry, would increase with severity of DR, and that pan-retinal photocoagulation (PRP) would exacerbate this dysfunction. Methods Dark adaptation (DA) was measured in subjects with diabetes mellitus and healthy controls. Dark adaptation was measured at 5° superior to the fovea following a flash bleach, and the data were analyzed to yield cone and rod sensitivity curves. Retinal layer thicknesses were quantified using spectral-domain optical coherence tomography (OCT). Results The sample consisted of 23 controls and 73 diabetic subjects. Subjects with moderate nonproliferative diabetic retinopathy (NPDR) exhibited significant impairment of rod recovery rate compared with control subjects (P = 0.04). Cone sensitivity was impaired in subjects with proliferative diabetic retinopathy (PDR) (type 1 diabetes mellitus [T1DM]: P = 0.0047; type 2 diabetes mellitus [T2DM]: P < 0.001). Subjects with untreated PDR compared with subjects treated with PRP exhibited similar rod recovery rates and cone sensitivities. Thinner RPE as assessed by OCT was associated with slower rod recovery and lower cone sensitivity, and thinner photoreceptor inner segment/outer segment layer was associated with lower cone sensitivity. Conclusions The results suggest that RPE and photoreceptor cell dysfunction, as assessed by cone sensitivity level and rod- and RPE-mediated dark adaptation, progresses with worsening DR, and rod recovery dysfunction occurs earlier than cone dysfunction. Function was preserved following PRP. The findings suggest multiple defects in retinoid function and provide potential points to improve visual function in persons with PDR. PMID:26803796

Numerical and analytical studies of critical radius in spherical and cylindrical geometries for corona discharge in air and CO2-rich environments

NASA Astrophysics Data System (ADS)

Engle, J. A.; Riousset, J. A.

2016-12-01

In order to determine the most effective geometry of a lightning rod, one must first understand the physical difference between their current designs. Benjamin Franklin's original theory of sharp tipped rods suggests an increase of local electric field, while Moore et al.'s (2000) studies of rounded tips evince an increased probability of strike (Moore et al., 2000; Gibson et al., 2009).In this analysis, the plasma discharge is produced between two electrodes with a high potential difference, resulting in ionization of the neutral gas particle. This process, when done at low current and low temperature can create a corona discharges, which can be observed as a luminescent emission. The Cartesian geometry known as Paschen, or Townsend, theory is particularly well suited to model experimental laboratory scenario, however, it is limited in its applicability to lightning rods. Franklin's sharp tip and Moore et al.'s (2000) rounded tip fundamentally differ in the radius of curvature of the upper end of the rod. As a first approximation, the rod can be modelled as an equipotential conducting sphere above the ground. Hence, we expand the classic Cartesian geometry into spherical and cylindrical geometries. In this work we explore the effects of shifting from the classical parallel plate analysis to spherical and cylindrical geometries more adapted for studies of lightning rods or power lines. Utilizing Townsend's equation for corona discharge, we estimate a critical radius and minimum breakdown voltage that allows ionization of the air around an electrode. Additionally, we explore the influence of the gas in which the discharge develops. We use BOLSIG+, a numerical solver for the Boltzmann equation, to calculate Townsend coefficients for CO2-rich atmospheric conditions. This allows us to expand the scope of this study to other planetary bodies such as Mars (Hagelaar, 2005). We solve the problem both numerically and analytically to present simplified formulas per each geometry and gas mixture. The development of a numerical framework will ultimately let us test the influence of additional parameters such as background ionization, initiation criterion, and charge conservation on the values of the critical radius and minimum breakdown voltage.

Nuclear reactor shutdown control rod assembly

DOEpatents

Bilibin, Konstantin

1988-01-01

A temperature responsive, self-actuated nuclear reactor shutdown control rod assembly 10. The upper end 18 of a lower drive line 17 fits within the lower end of an upper drive line 12. The lower end (not shown) of the lower drive line 17 is connected to a neutron absorber. During normal temperature conditions the lower drive line 17 is supported by detent means 22,26. When an overtemperature condition occurs thermal actuation means 34 urges ring 26 upwardly sufficiently to allow balls 22 to move radially outwardly thereby allowing lower drive line 17 to move downwardly toward the core of the nuclear reactor resulting in automatic reduction of the reactor powder.

Experimental and theoretical study of iron and mild steel combustion in oxygen flows

NASA Astrophysics Data System (ADS)

El-Rabii, Hazem; Kazakov, Kirill A.; Muller, Maryse

2017-03-01

The effects of oxygen flow speed and pressure on the iron and mild steel combustion are investigated experimentally and theoretically. The studied specimens are vertical cylindrical rods subjected to an axial oxygen flow and ignited at the upper end by laser irradiation. Three main stages of the combustion process have been identified experimentally: (1) induction period, during which the rod is heated until an intensive metal oxidation begins at its upper end; (2) static combustion, during which a laminar liquid "cap'' slowly grows on the upper rod end, and, after the liquid cap detachment from the sample; (3) dynamic combustion, which is characterized by a rapid metal consumption and turbulent liquid motions. An analytical description of these stages is given. In particular, a model of the dynamic combustion is constructed based on the turbulent oxygen transport through the liquid metal-oxide flow. This model yields a simple expression for the fraction of metal burned in the process and allows one to calculate the normal propagation speed of the solid metal-liquid interface as a function of the oxygen flow speed and pressure. A comparison of the theory with the experimental results is made, and its potential application is mentioned.

Blowdown heat transfer separate-effects program. Quarterly progress report, October--December 1977. [PWR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, D.G.; Baucum, W.E.; Bohanan, R.E.

1977-10-01

The Thermal-Hydraulic Test Facility (THTF) has completed 20 powered rod blowdowns through October 13, 1977. Of these blowdowns, 5 were completed with all 49 rods powered, 2 were completed with 2 inactive rods, and 13 were completed with 4 inactive rods. Initial system pressure was 15.5 MPa, test section inlet temperature was 559 K, and break area was equivalent to a 200% break with the total area usually split between inlet and outlet in the ratio 0.40 : 0.60. Heater rod power was 80, 100, or 122 kW/rod, and the test section temperature was 607 K, 598 K, or 589more » K. Mean time to critical heat flux (CHF) varied from 0.7 to 1.4 sec with delayed CHF of 2.5 sec occurring in the upper half of the bundle in some tests.« less

Method and device for tensile testing of cable bundles

DOEpatents

Robertson, Lawrence M; Ardelean, Emil V; Goodding, James C; Babuska, Vit

2012-10-16

A standard tensile test device is improved to accurately measure the mechanical properties of stranded cables, ropes, and other composite structures wherein a witness is attached to the top and bottom mounting blocks holding the cable under test. The witness is comprised of two parts: a top and a bottom rod of similar diameter with the bottom rod having a smaller diameter stem on its upper end and the top rod having a hollow opening in its lower end into which the stem fits forming a witness joint. A small gap is present between the top rod and the larger diameter portion of the bottom rod. A standard extensometer is attached to the top and bottom rods of the witness spanning this small witness gap. When a force is applied to separate the mounting blocks, the gap in the witness expands the same length that the entire test specimen is stretched.

Role of extrinsic noise in the sensitivity of the rod pathway: rapid dark adaptation of nocturnal vision in humans.

PubMed

Reeves, Adam; Grayhem, Rebecca

2016-03-01

Rod-mediated 500 nm test spots were flashed in Maxwellian view at 5 deg eccentricity, both on steady 10.4 deg fields of intensities (I) from 0.00001 to 1.0 scotopic troland (sc td) and from 0.2 s to 1 s after extinguishing the field. On dim fields, thresholds of tiny (5') tests were proportional to √I (Rose-DeVries law), while thresholds after extinction fell within 0.6 s to the fully dark-adapted absolute threshold. Thresholds of large (1.3 deg) tests were proportional to I (Weber law) and extinction thresholds, to √I. rod thresholds are elevated by photon-driven noise from dim fields that disappears at field extinction; large spot thresholds are additionally elevated by neural light adaptation proportional to √I. At night, recovery from dimly lit fields is fast, not slow.

Long-term effects of retinopathy of prematurity (ROP) on rod and rod-driven function.

PubMed

Harris, Maureen E; Moskowitz, Anne; Fulton, Anne B; Hansen, Ronald M

2011-02-01

The purpose of this study was to determine whether recovery of scotopic sensitivity occurs in human ROP, as it does in the rat models of ROP. Following a cross-sectional design, scotopic electroretinographic (ERG) responses to full-field stimuli were recorded from 85 subjects with a history of preterm birth. In 39 of these subjects, dark adapted visual threshold was also measured. Subjects were tested post-term as infants (median age 2.5 months) or at older ages (median age 10.5 years) and stratified by severity of ROP: severe, mild, or none. Rod photoreceptor sensitivity, S (ROD), was derived from the a-wave, and post-receptor sensitivity, log σ, was calculated from the b-wave stimulus-response function. Dark adapted visual threshold was measured using a forced-choice preferential procedure. For S (ROD), the deficit from normal for age varied significantly with ROP severity but not with age group. For log σ, in mild ROP, the deficit was smaller in older subjects than in infants, while in severe ROP, the deficit was quite large in both age groups. In subjects who never had ROP, S (ROD) and log σ in both age groups were similar to those in term born controls. Deficits in dark adapted threshold and log σ were correlated in mild but not in severe ROP. The data are evidence that sensitivity of the post-receptor retina improves in those with a history of mild ROP. We speculate that beneficial reorganization of the post-receptor neural circuitry occurs in mild but not in severe ROP.

Null mutation in the rhodopsin kinase gene slows recovery kinetics of rod and cone phototransduction in man

PubMed Central

Cideciyan, Artur V.; Zhao, Xinyu; Nielsen, Lori; Khani, Shahrokh C.; Jacobson, Samuel G.; Palczewski, Krzysztof

1998-01-01

Rhodopsin kinase (RK), a specialized G-protein-coupled receptor kinase expressed in retina, is involved in quenching of light-induced signal transduction in photoreceptors. The role of RK in recovery after photoactivation has been explored in vitro and in vivo experimentally but has not been specifically defined in humans. We investigated the effects on human vision of a mutation in the RK gene causing Oguchi disease, a recessively inherited retinopathy. In vitro experiments demonstrated that the mutation, a deletion of exon 5, abolishes the enzymatic activity of RK and is likely a null. Both a homozygote and heterozygote with this RK mutation had recovery phase abnormalities of rod-isolated photoresponses by electroretinography (ERG); photoactivation was normal. Kinetics of rod bleaching adaptation by psychophysics were dramatically slowed in the homozygote but normal final thresholds were attained. Light adaptation was normal at low backgrounds but became abnormal at higher backgrounds. A slight slowing of cone deactivation kinetics in the homozygote was detected by ERG. Cone bleaching adaptation and background adaptation were normal. In this human in vivo condition without a functional RK and probable lack of phosphorylation and arrestin binding to activated rhodopsin, reduction of photolyzed chromophore and regeneration processes with 11-cis-retinal probably constitute the sole pathway for recovery of rod sensitivity. The role of RK in rods would thus be to accelerate inactivation of activated rhodopsin molecules that in concert with regeneration leads to the normal rate of recovery of sensitivity. Cones may rely mainly on regeneration for the inactivation of photolyzed visual pigment, but RK also contributes to cone recovery. PMID:9419375

Unstable upper and middle thoracic fractures. Preliminary experience with a posterior transpedicular correction-fixation technique.

PubMed

Payer, M

2005-06-01

A number of conservative and operative approaches have been described for the treatment of unstable traumatic upper and middle thoracic fractures. The advantage of surgical correction and fixation/fusion lies in its potential to restore sagittal and coronal alignment, thereby indirectly decompressing the spinal cord. A consecutive series of 8 patients with unstable traumatic upper and middle thoracic fractures is reviewed. In all patients, polyaxial pedicle screws were inserted bilaterally into the two levels above and below the fracture. Rods that were less contoured ("undercontoured") than the regional hyperkyphosis at the injured level, were anchored to the caudal four screws. The cranial four screws, with the vertebrae to which they were inserted, were then progressively pulled posteriorly onto the undercontoured rods with rod reducers, thus correcting the hyperkyphosis and anterolisthesis. The mean follow-up was 15 months. The mean regional kyphosis was 23 degrees preoperatively, 17 degrees postoperatively and 18 degrees at follow-up. The mean anterolisthesis was 8 mm preoperatively, 1 mm postoperatively and 1 mm at follow-up. No hardware failure occurred. Five patients with complete spinal cord injury at presentation made no neurological recovery, two patients with incomplete spinal cord injury initially (ASIA B), recovered substantially (to ASIA D), and the patients who were neurologically intact at presentation remained so.

Luminance and chromatic signals interact differently with melanopsin activation to control the pupil light response.

PubMed

Barrionuevo, Pablo A; Cao, Dingcai

2016-09-01

Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin. These cells receive afferent inputs from rods and cones, which provide inputs to the postreceptoral visual pathways. It is unknown, however, how melanopsin activation is integrated with postreceptoral signals to control the pupillary light reflex. This study reports human flicker pupillary responses measured using stimuli generated with a five-primary photostimulator that selectively modulated melanopsin, rod, S-, M-, and L-cone excitations in isolation, or in combination to produce postreceptoral signals. We first analyzed the light adaptation behavior of melanopsin activation and rod and cones signals. Second, we determined how melanopsin is integrated with postreceptoral signals by testing with cone luminance, chromatic blue-yellow, and chromatic red-green stimuli that were processed by magnocellular (MC), koniocellular (KC), and parvocellular (PC) pathways, respectively. A combined rod and melanopsin response was also measured. The relative phase of the postreceptoral signals was varied with respect to the melanopsin phase. The results showed that light adaptation behavior for all conditions was weaker than typical Weber adaptation. Melanopsin activation combined linearly with luminance, S-cone, and rod inputs, suggesting the locus of integration with MC and KC signals was retinal. The melanopsin contribution to phasic pupil responses was lower than luminance contributions, but much higher than S-cone contributions. Chromatic red-green modulation interacted with melanopsin activation nonlinearly as described by a "winner-takes-all" process, suggesting the integration with PC signals might be mediated by a postretinal site.

Ex Vivo ERG analysis of photoreceptors using an In Vivo ERG system

PubMed Central

Vinberg, Frans; Kolesnikov, Alexander V.; Kefalov, Vladimir J.

2014-01-01

The Function of the retina and effects of drugs on it can be assessed by recording transretinal voltage across isolated retina that is perfused with physiological medium. However, building ex vivo ERG apparatus requires substantial amount of time, resources and expertise. Here we adapted a commercial in vivo ERG system for transretinal ERG recordings from rod and cone photoreceptors and compared rod and cone signalling between ex vivo and in vivo environments. We found that the rod and cone a- and b-waves recorded with the transretinal ERG adapter and a standard in vivo ERG system are comparable to those obtained from live anesthetized animals. However, ex vivo responses are somewhat slower and their oscillatory potentials are suppressed as compared to those recorded in vivo. We found that rod amplification constant (A) was comparable between ex vivo and in vivo conditions, ∼10 - 30 s-2 depending on the choice of response normalization. We estimate that the A in cones is between 3 and 6 s-2 in ex vivo conditions and by assuming equal A in vivo we arrive to light funnelling factor of 3 for cones in the mouse retina. The ex vivo ERG adapter provides a simple and affordable alternative to designing a custom-built transretinal recordings setup for the study of photoreceptors. Our results provide a roadmap to the rigorous quantitative analysis of rod and cone responses made possible with such a system. PMID:24959652

In Vivo Two-Photon Fluorescence Kinetics of Primate Rods and Cones

PubMed Central

Sharma, Robin; Schwarz, Christina; Williams, David R.; Palczewska, Grazyna; Palczewski, Krzysztof; Hunter, Jennifer J.

2016-01-01

Purpose The retinoid cycle maintains vision by regenerating bleached visual pigment through metabolic events, the kinetics of which have been difficult to characterize in vivo. Two-photon fluorescence excitation has been used previously to track autofluorescence directly from retinoids and pyridines in the visual cycle in mouse and frog retinas, but the mechanisms of the retinoid cycle are not well understood in primates. Methods We developed a two-photon fluorescence adaptive optics scanning light ophthalmoscope dedicated to in vivo imaging in anesthetized macaques. Using pulsed light at 730 nm, two-photon fluorescence was captured from rods and cones during light and dark adaptation through the eye's pupil. Results The fluorescence from rods and cones increased with light exposure but at different rates. During dark adaptation, autofluorescence declined, with cone autofluorescence decreasing approximately 4 times faster than from rods. Rates of autofluorescence decrease in rods and cones were approximately 4 times faster than their respective rates of photopigment regeneration. Also, subsets of sparsely distributed cones were less fluorescent than their neighbors immediately following bleach at 565 nm and they were comparable with the S cone mosaic in density and distribution. Conclusions Although other molecules could be contributing, we posit that these fluorescence changes are mediated by products of the retinoid cycle. In vivo two-photon ophthalmoscopy provides a way to monitor noninvasively stages of the retinoid cycle that were previously inaccessible in the living primate eye. This can be used to assess objectively photoreceptor function in normal and diseased retinas. PMID:26903225

Light adaptation and the evolution of vertebrate photoreceptors.

PubMed

Morshedian, Ala; Fain, Gordon L

2017-07-15

Lamprey are cyclostomes, a group of vertebrates that diverged from lines leading to jawed vertebrates (including mammals) in the late Cambrian, 500 million years ago. It may therefore be possible to infer properties of photoreceptors in early vertebrate progenitors by comparing lamprey to other vertebrates. We show that lamprey rods and cones respond to light much like rods and cones in amphibians and mammals. They operate over a similar range of light intensities and adapt to backgrounds and bleaches nearly identically. These correspondences are pervasive and detailed; they argue for the presence of rods and cones very early in the evolution of vertebrates with properties much like those of rods and cones in existing vertebrate species. The earliest vertebrates were agnathans - fish-like organisms without jaws, which first appeared near the end of the Cambrian radiation. One group of agnathans became cyclostomes, which include lamprey and hagfish. Other agnathans gave rise to jawed vertebrates or gnathostomes, the group including all other existing vertebrate species. Because cyclostomes diverged from other vertebrates 500 million years ago, it may be possible to infer some of the properties of the retina of early vertebrate progenitors by comparing lamprey to other vertebrates. We have previously shown that rods and cones in lamprey respond to light much like photoreceptors in other vertebrates and have a similar sensitivity. We now show that these affinities are even closer. Both rods and cones adapt to background light and to bleaches in a manner almost identical to other vertebrate photoreceptors. The operating range in darkness is nearly the same in lamprey and in amphibian or mammalian rods and cones; moreover background light shifts response-intensity curves downward and to the right over a similar range of ambient intensities. Rods show increment saturation at about the same intensity as mammalian rods, and cones never saturate. Bleaches decrease sensitivity in part by loss of quantum catch and in part by opsin activation of transduction. These correspondences are so numerous and pervasive that they are unlikely to result from convergent evolution but argue instead that early vertebrate progenitors of both cyclostomes and mammals had photoreceptors much like our own. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Recruitment of Rod Photoreceptors from Short-Wavelength-Sensitive Cones during the Evolution of Nocturnal Vision in Mammals.

PubMed

Kim, Jung-Woong; Yang, Hyun-Jin; Oel, Adam Phillip; Brooks, Matthew John; Jia, Li; Plachetzki, David Charles; Li, Wei; Allison, William Ted; Swaroop, Anand

2016-06-20

Vertebrate ancestors had only cone-like photoreceptors. The duplex retina evolved in jawless vertebrates with the advent of highly photosensitive rod-like photoreceptors. Despite cones being the arbiters of high-resolution color vision, rods emerged as the dominant photoreceptor in mammals during a nocturnal phase early in their evolution. We investigated the evolutionary and developmental origins of rods in two divergent vertebrate retinas. In mice, we discovered genetic and epigenetic vestiges of short-wavelength cones in developing rods, and cell-lineage tracing validated the genesis of rods from S cones. Curiously, rods did not derive from S cones in zebrafish. Our study illuminates several questions regarding the evolution of duplex retina and supports the hypothesis that, in mammals, the S-cone lineage was recruited via the Maf-family transcription factor NRL to augment rod photoreceptors. We propose that this developmental mechanism allowed the adaptive exploitation of scotopic niches during the nocturnal bottleneck early in mammalian evolution. Published by Elsevier Inc.

The rod-driven a-wave of the dark-adapted mammalian electroretinogram.

PubMed

Robson, John G; Frishman, Laura J

2014-03-01

The a-wave of the electroretinogram (ERG) reflects the response of photoreceptors to light, but what determines the exact waveform of the recorded voltage is not entirely understood. We have now simulated the trans-retinal voltage generated by the photocurrent of dark-adapted mammalian rods, using an electrical model based on the in vitro measurements of Hagins et al. (1970) and Arden (1976) in rat retinas. Our simulations indicate that in addition to the voltage produced by extracellular flow of photocurrent from rod outer to inner segments, a substantial fraction of the recorded a-wave is generated by current that flows in the outer nuclear layer (ONL) to hyperpolarize the rod axon and synaptic terminal. This current includes a transient capacitive component that contributes an initial negative "nose" to the trans-retinal voltage when the stimulus is strong. Recordings in various species of the a-wave, including the peak and initial recovery towards the baseline, are consistent with simulations showing an initial transient primarily related to capacitive currents in the ONL. Existence of these capacitive currents can explain why there is always a substantial residual transient a-wave when post-receptoral responses are pharmacologically inactivated in rodents and nonhuman primates, or severely genetically compromised in humans (e.g. complete congenital stationary night blindness) and nob mice. Our simulations and analysis of ERGs indicate that the timing of the leading edge and peak of dark-adapted a-waves evoked by strong stimuli could be used in a simple way to estimate rod sensitivity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Robotic Telesurgery Research

DTIC Science & Technology

2009-03-01

closed (right) positions. The upper jaw is constructed out of a super-elastic shape- memory nickel titanium alloy ( Nitinol ) ribbon (Memry Corporation...tissue. The Nitinol ribbon is glued to a fixed nylon rod insert that fits inside the bottom jaw. The nylon rod is also glued to the bottom jaw, and...configurations (bottom). The two collar pieces are connected to one another by two 0.12 mm thick Nitinol ribbons that are anchored to the collar walls. A

Lightweight piston-rod assembly for a reciprocating machine

DOEpatents

Corey, John A.; Walsh, Michael M.

1986-01-01

In a reciprocating machine, there is provided a hollow piston including a dome portion on one end and a base portion on the opposite end. The base portion includes a central bore into which a rod is hermetically fixed in radial and angular alignment. The extending end of the rod has a reduced diameter portion adapted to fit into the central bore of a second member such as a cross-head assembly, and to be secured thereto in radial and axial alignment with the piston.

Quarterly progress report on Blowdown Heat Transfer Separate-Effects Program for January--March 1978. [PWR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, D.G.; Bohanan, R.E.; Clark, D.L.

1978-06-30

The Thermal-Hydraulic Test Facility (THTF) has completed 24 powered rod blowdowns through Mar. 9, 1978. Of these blowdowns, 5 were completed with all 49 rods powered, 2 were completed with 2 inactive rods, and 13 were completed with 4 inactive rods. Initial system pressure was approximately 15.5 MPa (approximately 2250 psi), test section inlet temperature was approximately 559/sup 0/K (approximately 547/sup 0/F), and break area was equivalent to a 200 percent break with the total area usually split between inlet and outlet in the ratio 0.40 : 0.60. Heater rod power was 80, 100, or 122 kW/rod, and the testmore » section outlet temperature was 607/sup 0/K (632/sup 0/F), 598/sup 0/K (617/sup 0/F), or 589/sup 0/K (600/sup 0/F). Mean time to CHF varied from 0.7 to 1.4 sec, with delayed CHF of approximately 2.5 sec occurring in the upper half of the bundle in some tests.« less

Design and evaluation of a bolted joint for a discrete carbon-epoxy rod-reinforced hat section

NASA Technical Reports Server (NTRS)

Rousseau, Carl Q.; Baker, Donald J.

1996-01-01

The use of prefabricated pultruded carbon-epoxy rods has reduced the manufacturing complexity and costs of stiffened composite panels while increasing the damage tolerance of the panels. However, repairability of these highly efficient discrete stiffeners has been a concern. Design, analysis, and test results are presented in this paper for a bolted-joint repair for the pultruded rod concept that is capable of efficiently transferring axial loads in a hat-section stiffener on the upper skin segment of a heavily loaded aircraft wing component. A tension and a compression joint design were evaluated. The tension joint design achieved approximately 1.0% strain in the carbon-epoxy rod-reinforced hat-section and failed in a metal fitting at 166% of the design ultimate load. The compression joint design failed in the carbon-epoxy rod-reinforced hat-section test specimen area at approximately 0.7% strain and at 110% of the design ultimate load. This strain level of 0.7% in compression is similar to the failure strain observed in previously reported carbon-epoxy rod-reinforced hat-section column tests.

Folding chair

DOEpatents

Cornell, Howell N.

1985-08-20

A foldable chair of the lawn chair type has ground-engaging front and rear legs, attached to and carrying a back frame and seat frame, the back frame and seat frame being pivotally attached to a spreader rod which extends beyond the back and seat frames to bear against one of the leg members when the chair is unfolded. A contact pad mounted on the extending portion of the spreader rod is formed as an externally-contoured bushing fit over the spreader rod and adapted to engage the leg member to restrict side-to-side movement of the spreader rod, with respect to the leg member, when the chair is unfolded.

High Energy Absorption Top Nozzle For A Nuclaer Fuel Assembly

DOEpatents

Sparrow, James A.; Aleshin, Yuriy; Slyeptsov, Aleksey

2004-05-18

A high energy absorption top nozzle for a nuclear fuel assembly that employs an elongated upper tubular housing and an elongated lower tubular housing slidable within the upper tubular housing. The upper and lower housings are biased away from each other by a plurality of longitudinally extending springs that are restrained by a longitudinally moveable piston whose upward travel is limited within the upper housing. The energy imparted to the nozzle by a control rod scram is mostly absorbed by the springs and the hydraulic affect of the piston within the nozzle.

Variation in rod and cone density from the fovea to the mid-periphery in healthy human retinas using adaptive optics scanning laser ophthalmoscopy

PubMed Central

Wells-Gray, E M; Choi, S S; Bries, A; Doble, N

2016-01-01

Purpose To characterize the rod and cone photoreceptor mosaic at retinal locations spanning the central 60° in vivo using adaptive optics scanning laser ophthalmoscopy (AO-SLO) in healthy human eyes. Methods AO-SLO images (0.7 × 0.9°) were acquired at 680 nm from 14 locations from 30° nasal retina (NR) to 30° temporal retina (TR) in 5 subjects. Registered averaged images were used to measure rod and cone density and spacing within 60 × 60 μm regions of interest. Voronoi analysis was performed to examine packing geometry at all locations. Results Average peak cone density near the fovea was 164 000±24 000 cones/mm2 and decreased to 6700±1500 and 5400±700 cones/mm2 at 30° NR and 30° TR, respectively. Cone-to-cone spacing increased from 2.7±0.2 μm at the fovea to 14.6±1.4 μm at 30° NR and 16.3±0.7 μm at 30° TR. Rod density peaked at 25° NR (124 000±20 000 rods/mm2) and 20° TR (120 000±12 000 rods/mm2) and decreased at higher eccentricities. Center-to-center rod spacing was lowest nasally at 25° (2.1±0.1 μm). Temporally, rod spacing was lowest at 20° (2.2±0.1 μm) before increasing to 2.3±0.1 μm at 30° TR. Conclusions Both rod and cone densities showed good agreement with histology and prior AO-SLO studies. The results demonstrate the ability to image at higher retinal eccentricities than reported previously. This has clinical importance in diseases that initially affect the peripheral retina such as retinitis pigmentosa. PMID:27229708

Superfund record of decision amendment (EPA Region 3): Tyson Dump Superfund Site, Upper Merion Township, Montgomergy County, PA, July 20, 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1996-08-01

The Record of Decision Amendment (`ROD Amendment`) modifies the selected remedy described in the Revised Record of Decision for the Tyson`s Superfund Site (Site) issued by the U.S. Environmental Protection Agency (EPA) on March 31, 1988 (1988 Revised ROD - PB89-233894). In the 1988 Revised ROD, EPA selected a soil vapor extraction (SVE) remedy for lagoon area soils. The SVE system has removed approximately 200,000 pounds of volatile organic compounds (VOCs) from the lagoon area soils. Although several enhancements and modifications have been employed to improve performance, the SVE system will not achieve the cleanup standards specified in the 1988more » Revised ROD. The decision document presents the selected remedial action for the lagoon area soils at the Tyson`s Site.« less

Mouse rods signal through gap junctions with cones.

PubMed

Asteriti, Sabrina; Gargini, Claudia; Cangiano, Lorenzo

2014-01-01

Rod and cone photoreceptors are coupled by gap junctions (GJs), relatively large channels able to mediate both electrical and molecular communication. Despite their critical location in our visual system and evidence that they are dynamically gated for dark/light adaptation, the full impact that rod-cone GJs can have on cone function is not known. We recorded the photovoltage of mouse cones and found that the initial level of rod input increased spontaneously after obtaining intracellular access. This process allowed us to explore the underlying coupling capacity to rods, revealing that fully coupled cones acquire a striking rod-like phenotype. Calcium, a candidate mediator of the coupling process, does not appear to be involved on the cone side of the junctional channels. Our findings show that the anatomical substrate is adequate for rod-cone coupling to play an important role in vision and, possibly, in biochemical signaling among photoreceptors. DOI: http://dx.doi.org/10.7554/eLife.01386.001.

Rod phototransduction determines the trade-off of temporal integration and speed of vision in dark-adapted toads.

PubMed

Haldin, Charlotte; Nymark, Soile; Aho, Ann-Christine; Koskelainen, Ari; Donner, Kristian

2009-05-06

Human vision is approximately 10 times less sensitive than toad vision on a cool night. Here, we investigate (1) how far differences in the capacity for temporal integration underlie such differences in sensitivity and (2) whether the response kinetics of the rod photoreceptors can explain temporal integration at the behavioral level. The toad was studied as a model that allows experimentation at different body temperatures. Sensitivity, integration time, and temporal accuracy of vision were measured psychophysically by recording snapping at worm dummies moving at different velocities. Rod photoresponses were studied by ERG recording across the isolated retina. In both types of experiments, the general timescale of vision was varied by using two temperatures, 15 and 25 degrees C. Behavioral integration times were 4.3 s at 15 degrees C and 0.9 s at 25 degrees C, and rod integration times were 4.2-4.3 s at 15 degrees C and 1.0-1.3 s at 25 degrees C. Maximal behavioral sensitivity was fivefold lower at 25 degrees C than at 15 degrees C, which can be accounted for by inability of the "warm" toads to integrate light over longer times than the rods. However, the long integration time at 15 degrees C, allowing high sensitivity, degraded the accuracy of snapping toward quickly moving worms. We conclude that temporal integration explains a considerable part of all variation in absolute visual sensitivity. The strong correlation between rods and behavior suggests that the integration time of dark-adapted vision is set by rod phototransduction at the input to the visual system. This implies that there is an inexorable trade-off between temporal integration and resolution.

The retinal rod Na(+)/Ca(2+),K(+) exchanger contains a noncleaved signal sequence required for translocation of the N terminus.

PubMed

McKiernan, C J; Friedlander, M

1999-12-31

The retinal rod Na(+)/Ca(2+),K(+) exchanger (RodX) is a polytopic membrane protein found in photoreceptor outer segments where it is the principal extruder of Ca(2+) ions during light adaptation. We have examined the role of the N-terminal 65 amino acids in targeting, translocation, and integration of the RodX using an in vitro translation/translocation system. cDNAs encoding human RodX and bovine RodX through the first transmembrane domain were correctly targeted and integrated into microsomal membranes; deletion of the N-terminal 65 amino acids (aa) resulted in a translation product that was not targeted or integrated. Deletion of the first 65 aa had no effect on membrane targeting of full-length RodX, but the N-terminal hydrophilic domain no longer translocated. Chimeric constructs encoding the first 65 aa of bovine RodX fused to globin were translocated across microsomal membranes, demonstrating that the sequence could function heterologously. Studies of fresh bovine retinal extracts demonstrated that the first 65 aa are present in the native protein. These data demonstrate that the first 65 aa of RodX constitute an uncleaved signal sequence required for the efficient membrane targeting and proper membrane integration of RodX.

Safety control circuit for a neutronic reactor

DOEpatents

Ellsworth, Howard C.

2004-04-27

A neutronic reactor comprising an active portion containing material fissionable by neutrons of thermal energy, means to control a neutronic chain reaction within the reactor comprising a safety device and a regulating device, a safety device including means defining a vertical channel extending into the reactor from an aperture in the upper surface of the reactor, a rod containing neutron-absorbing materials slidably disposed within the channel, means for maintaining the safety rod in a withdrawn position relative to the active portion of the reactor including means for releasing said rod on actuation thereof, a hopper mounted above the active portion of the reactor having a door disposed at the bottom of the hopper opening into the vertical channel, a plurality of bodies of neutron-absorbing materials disposed within the hopper, and means responsive to the failure of the safety rod on actuation thereof to enter the active portion of the reactor for opening the door in the hopper.

Modular anode assemblies and methods of using the same for electrochemical reduction

DOEpatents

Wiedmeyer, Stanley G; Barnes, Laurel A; Williamson, Mark A; Willit, James L

2015-02-17

Modular anode assemblies are used in electrolytic oxide reduction systems for scalable reduced metal production via electrolysis. Assemblies include a channel frame connected to several anode rods extending into an electrolyte. An electrical system powers the rods while being insulated from the channel frame. A cooling system removes heat from anode rods and the electrical system. An anode guard attaches to the channel frame to prevent accidental electrocution or damage during handling or repositioning. Each anode rod may be divided into upper and lower sections to permit easy repair and swapping out of lower sections. The modular assemblies may have standardized components to permit placement at multiple points within a reducing system. Example methods may operate an electrolytic oxide reduction system by positioning the modular anode assemblies in the reduction system and applying electrical power to the plurality of anode assemblies.

Pulse-actuated fuel-injection spark plug

DOEpatents

Murray, Ian; Tatro, Clement A.

1978-01-01

A replacement spark plug for reciprocating internal combustion engines that functions as a fuel injector and as a spark plug to provide a "stratified-charge" effect. The conventional carburetor is retained to supply the main fuel-air mixture which may be very lean because of the stratified charge. The replacement plug includes a cylindrical piezoelectric ceramic which contracts to act as a pump whenever an ignition pulse is applied to a central rod through the ceramic. The rod is hollow at its upper end for receiving fuel, it is tapered along its lower length to act as a pump, and it is flattened at its lower end to act as a valve for fuel injection from the pump into the cylinder. The rod also acts as the center electrode of the plug, with the spark jumping from the plug base to the lower end of the rod to thereby provide spark ignition that has inherent proper timing with the fuel injection.

Nuclear reactor shutdown system

DOEpatents

Bhate, Suresh K.; Cooper, Martin H.; Riffe, Delmar R.; Kinney, Calvin L.

1981-01-01

An inherent shutdown system for a nuclear reactor having neutron absorbing rods affixed to an armature which is held in an upper position by a magnetic flux flowing through a Curie temperature material. The Curie temperature material is fixedly positioned about the exterior of an inner duct in an annular region through which reactor coolant flows. Elongated fuel rods extending from within the core upwardly toward the Curie temperature material are preferably disposed within the annular region. Upon abnormal conditions which result in high neutron flux and coolant temperature, the Curie material loses its magnetic permeability, breaking the magnetic flux path and allowing the armature and absorber rods to drop into the core, thus shutting down the fissioning reaction. The armature and absorber rods are retrieved by lowering the housing for the electromagnet forming coils which create a magnetic flux path which includes the inner duct wall. The coil housing then is raised, resetting the armature.

The effects of L-glutamate, AMPA, quisqualate, and kainate on retinal horizontal cells depend on adaptational state: implications for rod-cone interactions.

PubMed

Krizaj, D; Akopian, A; Witkovsky, P

1994-09-01

We studied the responses of isolated and intact luminosity-type horizontal cells (L-HC) in the Xenopus retina to L-glutamate (L-glu) and its analogs. Isolated L-HCs studied with whole-cell patch clamp responded to L-glu, kainate (KA), AMPA, or quisqualate (quis) with inward currents from a holding potential of -60 mV, associated with a conductance increase. The current elicited by KA was relatively large and sustained, whereas AMPA or quis evoked a desensitizing current. Coapplication of quis and KA resulted in a smaller current and conductance change than that evoked by a pulse of either alone at the same concentration. This finding suggests that the L-HC has a single subtype of glutamate receptor that responds to both quis and KA. Prior exposure to dopamine enhanced the KA-evoked current about twofold. In the superfused eyecup we found that L-HC responses to quinoxalinediones (CNQX or DNQX) and to L-glu, KA, AMPA, and quis varied as a function of adaptational state. When driven exclusively by either cones or by rods, CNQX/DNQX hyperpolarized the L-HC and reduced its light response, without altering response kinetics, indicating that both rods and cones communicate with L-HCs at ionotropic glutamatergic synapses. Under mesopic conditions, however, as CNQX or DNQX reduced cone input, the rod input to the L-HC increased up to fivefold in magnitude and had slowed kinetics. The depolarizing response of the L-HC to L-glu, AMPA, or quis was relatively small and transient under photopic conditions, but was much larger and sustained when the eyecup was dark adapted. The D1 dopamine antagonist SCH 23390 potentiated the response to quis. In contrast, responses to KA were largest in light-adapted eyecups, were potentiated by a D1 dopamine agonist, SKF 38393, and were reduced by SCH 23390. We hypothesize that the segregated populations of glutamate receptors in the L-HC opposite cone and rod synaptic endings can be separately modulated to respond differentially to the native transmitter, glutamate. In photopic and mesopic states the dominant cone input tonically inhibits rod to L-HC communication. This inhibition appears to occur at the postsynaptic membrane and may be mediated by second messengers.

Design and Evaluation of a Bolted Joint for a Discrete Carbon-Epoxy Rod-Reinforced Hat Section

NASA Technical Reports Server (NTRS)

Baker, Donald J.; Rousseau, Carl Q.

1996-01-01

The use of pre-fabricated pultruded carbon-epoxy rods has reduced the manufacturing complexity and costs of stiffened composite panels while increasing the damage tolerance of the panels. However, repairability of these highly efficient discrete stiffeners has been a concern. Design, analysis, and test results are presented in this paper for a bolted-joint repair for the pultruded rod concept that is capable of efficiently transferring axial loads in a hat-section stiffener on the upper skin segment of a heavily loaded aircraft wing component. A tension and a compression joint design were evaluated. The tension joint design achieved approximately 1.0 percent strain in the carbon-epoxy rod-reinforced hat-section and failed in a metal fitting at 166 percent of the design ultimate load. The compression joint design failed in the carbon-epoxy rod-reinforced hat-section test specimen area at approximately 0.7 percent strain and at 110 percent of the design ultimate load. This strain level of 0.7 percent in compression is similar to the failure strain observed in previously reported carbon-epoxy rod-reinforced hat-section column tests.

Physiological and Microfluorometric Studies of Reduction and Clearance of Retinal in Bleached Rod Photoreceptors

PubMed Central

Tsina, Efthymia; Chen, Chunhe; Koutalos, Yiannis; Ala-Laurila, Petri; Tsacopoulos, Marco; Wiggert, Barbara; Crouch, Rosalie K.; Cornwall, M. Carter

2004-01-01

The visual cycle comprises a sequence of reactions that regenerate the visual pigment in photoreceptors during dark adaptation, starting with the reduction of all-trans retinal to all-trans retinol and its clearance from photoreceptors. We have followed the reduction of retinal and clearance of retinol within bleached outer segments of red rods isolated from salamander retina by measuring its intrinsic fluorescence. Following exposure to a bright light (bleach), increasing fluorescence intensity was observed to propagate along the outer segments in a direction from the proximal region adjacent to the inner segment toward the distal tip. Peak retinol fluorescence was achieved after ∼30 min, after which it declined very slowly. Clearance of retinol fluorescence is considerably accelerated by the presence of the exogenous lipophilic substances IRBP (interphotoreceptor retinoid binding protein) and serum albumin. We have used simultaneous fluorometric and electrophysiological measurements to compare the rate of reduction of all-trans retinal to all-trans retinol to the rate of recovery of flash response amplitude in these cells in the presence and absence of IRBP. We find that flash response recovery in rods is modestly accelerated in the presence of extracellular IRBP. These results suggest such substances may participate in the clearance of retinoids from rod photoreceptors, and that this clearance, at least in rods, may facilitate dark adaptation by accelerating the clearance of photoproducts of bleaching. PMID:15452202

Hydraulically-operated pump jack with chain drive

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ratell Jr., R. E.

1985-02-05

My invention relates to pumping apparatus, particularly to a hydraulically-operated pump jack for oil, brine water and the like. The apparatus is fabricated from steel plate to make a strong, but light-weight tower which may be easily transported from one site to another by a small boom truck or gin pole truck. In contrast to pump jacks of the walking beam type which are massive in size, my improved pump jack is compact and is seated on and secured directly to the head of an oil well casing. A vertically-arranged hydraulic cylinder has its piston rod connected to a crossmore » head on which a pair of sprockets are journalled. Chains pass around respective sprockets, one reach of each chain extending upwardly and is anchored to a stationary part of the tower. The other reach of each chain extends upwardly and over and around an upper sprocket journalled on a shaft carried by the upper end of the tower, each chain then extending downwardly to a yoke to which the polish rod is connected. This arrangement will result in a 2 to 1 ratio between the movement of the polish rod and the stroke of the hydraulic cylinder.« less

Fine structure of the retinal photoreceptors of the great horned owl (Bubo virginianus).

PubMed

Braekevelt, C R

1993-01-01

The retinal photoreceptors of the great horned owl (Bubo virginianus) consist of rods, single cones and unequal double cones present in a ratio of about 30:1.2. In the light-adapted state the rods are stout cells which are not felt to undergo retinomotor movements. The rod outer segment consists of a stack of scalloped membranous discs enclosed by the cell membrane. The rod inner segment shows an ellipsoid of mitochondria and a wealth of rough endoplasmic reticulum (RER) and polysomes, Golgi zones and autophagic vacuoles but not hyperboloid of glycogen. Single cones show a slightly tapered outer segment, a heterogenous oil droplet and an ellipsoid of mitochondria at the apex of the inner segment. Double cones consist of a larger chief member which also displays an oil droplet and a slightly smaller accessory member which does not. Both members of the double cone as well as the single cone show a prominent ellipsoid, plentiful polysomes and RER and Golgi zones in the inner segment. Neither single nor double cones possess a condensed paraboloid of glycogen but instead show plentiful scattered glycogen particles. Along the contiguous membranes between accessory and chief cones a few presumed junctional complexes are seen near the external limiting membrane. Judging by their morphology in light-adaptation the cones of this species do not undergo photomechanical movements. Rods and cones (both types) have both invaginated (ribbon) and numerous superficial (conventional) synaptic sites. Rods are more numerous in this nocturnally active bird than is usually noted in avian species.

Close packing of rods on spherical surfaces

NASA Astrophysics Data System (ADS)

Smallenburg, Frank; Löwen, Hartmut

2016-04-01

We study the optimal packing of short, hard spherocylinders confined to lie tangential to a spherical surface, using simulated annealing and molecular dynamics simulations. For clusters of up to twelve particles, we map out the changes in the geometry of the closest-packed configuration as a function of the aspect ratio L/D, where L is the cylinder length and D the diameter of the rods. We find a rich variety of cluster structures. For larger clusters, we find that the best-packed configurations up to around 100 particles are highly dependent on the exact number of particles and aspect ratio. For even larger clusters, we find largely disordered clusters for very short rods (L/D = 0.25), while slightly longer rods (L/D = 0.5 or 1) prefer a global baseball-like geometry of smectic-like domains, similar to the behavior of large-scale nematic shells. Intriguingly, we observe that when compared to their optimal flat-plane packing, short rods adapt to the spherical geometry more efficiently than both spheres and longer rods. Our results provide predictions for experimentally realizable systems of colloidal rods trapped at the interface of emulsion droplets.

Light adaptation and dark adaptation of human rod photoreceptors measured from the a-wave of the electroretinogram

PubMed Central

Thomas, M M; Lamb, T D

1999-01-01

We recorded the a-wave of the human electroretinogram from subjects with normal vision, using a corneal electrode and ganzfeld (full-field) light stimulation. From analysis of the rising phase of rod-isolated flash responses we determined the maximum size (amax) of the a-wave, a measure of the massed circulating current of the rods, and the amplification constant (A) of transduction within the rod photoreceptors.During light adaptation by steady backgrounds the maximal response was reduced, as reported previously. amax declined approximately as I0/(I0+IB), where IB is retinal illuminance and I0 is a constant. In different subjects I0 ranged from 40 to 100 trolands, with a mean of 70 trolands, corresponding to about 600 photoisomerizations s−1 per rod. (1 troland is the retinal illuminance that results when a surface luminance of 1 cd m−2 is viewed through a pupil area of 1 mm2.) The amplification constant A decreased only slightly in the presence of steady backgrounds.Following a full bleach amax recovered along an S-shaped curve over a period of 30 min. There was no detectable response for the first 5 min, and half-maximal recovery took 13-17 min.The apparent amplification constant decreased at early times after large bleaches. However, upon correction for reduced light absorption due to loss of pigment, with regeneration of rhodopsin occurring with a time constant of 9-15 min in different subjects, it appeared that the true value of A was probably unchanged by bleaching.The recovery of amax following a bleach could be converted into recovery of equivalent background intensity, using a ‘Crawford transformation’ derived from the light adaptation results. Following bleaches ranging from 10 to > 99 %, the equivalent background intensity decayed approximately exponentially, with a time constant of about 3 min.The time taken for amax to recover to a fixed proportion of its original level increased approximately linearly (rather than logarithmically) with fractional bleach, with a slope of about 12 min per 100 % bleach. Similar behaviour has previously been seen in psychophysical dark adaptation experiments, for the dependence of the ‘second component’ of recovery on the level of bleaching. PMID:10381594

Power-Tool Adapter For T-Handle Screws

NASA Technical Reports Server (NTRS)

Deloach, Stephen R.

1992-01-01

Proposed adapter enables use of pneumatic drill, electric drill, electric screwdriver, or similar power tool to tighten or loosen T-handled screws. Notched tube with perpendicular rod welded to it inserted in chuck of tool. Notched end of tube slipped over screw handle.

A modified efficient purse-string stapling technique (mEST) that uses a new metal rod for intracorporeal esophagojejunostomy in laparoscopic total gastrectomy

PubMed Central

Moon, Jeong-Ho; Yamamoto, Kazuyoshi; Yanagimoto, Yoshitomo; Sugimura, Keijirou; Miyata, Hiroshi; Yano, Masahiko; Sakon, Masato

2017-01-01

Intracorporeal esophagojejunostomy after laparoscopic total gastrectomy is technically difficult because this procedure should be performed in a narrow surgical field in the upper abdomen even when completely laparoscopic approaches are used. The placement of the anvil of a circular stapling device into the esophagus and connection the instrument to the anvil are extremely difficult steps in this surgery. Therefore, we developed a simple technique for intracorporeal esophagojejunostomy using hemi-double stapling technique; we named this technique the efficient purse-string stapling technique (EST). More recently, we have developed a modified EST (mEST) that utilizes a new stainless steel anvil rod instead of a plastic rod. Relative to the plastic rod, the steel rod is reusable and shorter; thus, it was easier to perform anvil placement into the esophagus with the steel rod. Anvil preparation for mEST: a stainless steel rod is attached to the shaft of the anvil, and the needle and thread are sutured to the tip of the rod. After complete insertion of the anvil into the esophageal cavity, the needle and thread are used to penetrate the anterior esophageal wall, and the esophagus is then clamped using a linear stapler just distal to the site penetrated by the thread. The linear stapler is fired, and anvil placement in the esophagus is simultaneously accomplished. After the rod is removed from the anvil, the instrument is intracorporeally connected to the anvil and then fired to complete the gastrojejunostomy. This technique is simple and facilitates intracorporeal reconstruction procedures in laparoscopic total gastrectomy. PMID:28815221

Rodded shutdown system for a nuclear reactor

DOEpatents

Golden, Martin P.; Govi, Aldo R.

1978-01-01

A top mounted nuclear reactor diverse rodded shutdown system utilizing gas fed into a pressure bearing bellows region sealed at the upper extremity to an armature. The armature is attached to a neutron absorber assembly by a series of shafts and connecting means. The armature is held in an uppermost position by an electromagnet assembly or by pressurized gas in a second embodiment. Deenergizing the electromagnet assembly, or venting the pressurized gas, causes the armature to fall by the force of gravity, thereby lowering the attached absorber assembly into the reactor core.

Efficacy Outcome Measures for Clinical Trials of USH2A caused by the Common c.2299delG Mutation.

PubMed

Calzetti, Giacomo; Levy, Richard A; Cideciyan, Artur V; Garafalo, Alexandra V; Roman, Alejandro J; Sumaroka, Alexander; Charng, Jason; Heon, Elise; Jacobson, Samuel G

2018-06-25

To determine the change in vision and retinal structure in patients with the common c.2299delG mutation in the USH2A gene in anticipation of clinical trials of therapy. Retrospective observational case series. Eighteen patients, homozygotes or compound heterozygotes with the c.2299delG mutation in USH2A, were studied with visual acuity, kinetic perimetry, dark- and light-adapted two-color static perimetry, optical coherence tomography (OCT) and autofluorescence (AF) imaging. Serial data were available for at least half of the patients depending on the parameter analyzed. The kinetics of disease progression in this specific molecular form of USH2A differed between the measured parameters. Visual acuity could remain normal for decades. Kinetic and light-adapted static perimetry across the entire visual field had similar rates of decline that were slower than those of rod-based perimetry. Horizontal OCT scans through the macula showed that IS/OS line width had a similar rate of constriction as co-localized AF imaging and cone-based light-adapted sensitivity extent. The rate of constriction of rod-based sensitivity extent across this same region was twice as rapid as that of cones. In patients with the c.2299delG mutation in USH2A, rod photoreceptors are the cells that express disease early and more aggressively than cones. Rod-based vision measurements in central or extracentral-peripheral retinal regions warrant monitoring in order to complete a clinical trial in a timely manner. Copyright © 2018. Published by Elsevier Inc.

Fundus-controlled two-color dark adaptometry with the Microperimeter MP1.

PubMed

Bowl, Wadim; Stieger, Knut; Lorenz, Birgit

2015-06-01

The aim of this study was to provide fundus-controlled two-color adaptometry with an existing device. A quick and easy approach extends the application possibilities of a commercial fundus-controlled perimeter. An external filter holder was placed in front the objective lens of the MP1 (Nidek, Italy) and fitted with filters to modify background, stimulus intensity, and color. Prior to dark adaptometry, the subject's visual sensitivity profile was measured for red and blue stimuli to determine whether rods or cones or both mediated the absolute threshold. After light adaptation, 20 healthy subjects were investigated with a pattern covering six spots at the posterior pole of the retina up to 45 min of dark adaptation. Thresholds were determined using a 200 ms red Goldmann IV and a blue Goldmann II stimulus. The pre-test sensitivity showed a typical distribution of values along the meridian, with high peripheral light increment sensitivity (LIS) and low central LIS for rods and the reverse for cones. After bleach, threshold recovery had a classic biphasic shape. The absolute threshold was reached after approximately 10 min for the red and 15 min for the blue stimulus. Two-color fundus-controlled adaptometry with a commercial MP1 without internal changes to the device provides a quick and easy examination of rod and cone function during dark adaptation at defined retinal loci of the posterior pole. This innovative method will be helpful to measure rod vs. cone function at known loci of the posterior pole in early stages of retinal degenerations.

Spatiotemporal regulation of ATP and Ca2+ dynamics in vertebrate rod and cone ribbon synapses

PubMed Central

Johnson, Jerry E.; Perkins, Guy A.; Giddabasappa, Anand; Chaney, Shawntay; Xiao, Weimin; White, Andrew D.; Brown, Joshua M.; Waggoner, Jenna; Ellisman, Mark H.

2007-01-01

Purpose In conventional neurons, Ca2+ enters presynaptic terminals during an action potential and its increased local concentration triggers transient exocytosis. In contrast, vertebrate photoreceptors are nonspiking neurons that maintain sustained depolarization and neurotransmitter release from ribbon synapses in darkness and produce light-dependent graded hyperpolarizing responses. Rods transmit single photon responses with high fidelity, whereas cones are less sensitive and exhibit faster response kinetics. These differences are likely due to variations in presynaptic Ca2+ dynamics. Metabolic coupling and cross-talk between mitochondria, endoplasmic reticulum (ER), plasma membrane Ca2+ ATPase (PMCA), and Na+-Ca2+ exchanger (NCX) coordinately control presynaptic ATP production and Ca2+ dynamics. The goal of our structural and functional studies was to determine the spatiotemporal regulation of ATP and Ca2+ dynamics in rod spherules and cone pedicles. Methods Central retina tissue from C57BL/6 mice was used. Laser scanning confocal microscopy (LSCM) experiments were conducted on fixed-frozen vertical sections. Primary antibodies were selected for their tissue/cellular specificity and ability to recognize single, multiple or all splice variants of selected isoforms. Electron microscopy (EM) and 3-D electron tomography (ET) studies used our standard procedures on thin- and thick-sectioned retinas, respectively. Calibrated fluo-3-Ca2+ imaging experiments of dark- and light-adapted rod and cone terminals in retinal slices were conducted. Results Confocal microscopy showed that mitochondria, ER, PMCA, and NCX1 exhibited distinct retinal lamination patterns and differential distribution in photoreceptor synapses. Antibodies for three distinct mitochondrial compartments differentially labeled retinal areas with high metabolic demand: rod and cone inner segments, previously undescribed cone juxtanuclear mitochondria and the two plexiform layers. Rod spherule membranes uniformly and intensely stained for PMCA, whereas the larger cone pedicles preferentially stained for NCX1 at their active zones and PMCA near their mitochondria. EM and ET revealed that mitochondria in rod spherules and cone pedicles differed markedly in their number, location, size, volume, and total cristae surface area, and cristae junction diameter. Rod spherules had one large ovoid mitochondrion located near its active zone, whereas cone pedicles averaged five medium-sized mitochondria clustered far from their active zones. Most spherules had one ribbon synapse, whereas pedicles contained numerous ribbon synapses. Fluo-3 imaging studies revealed that during darkness rod spherules maintained a lower [Ca2+] than cone pedicles, whereas during light adaptation pedicles rapidly lowered their [Ca2+] below that observed in spherules. Conclusions These findings indicate that ATP demand and mitochondrial ATP production are greater in cone pedicles than rod spherules. Rod spherules employ high affinity/low turnover PMCA and their mitochondrion to maintain a relatively low [Ca2+] in darkness, which increases their sensitivity and signal-to-noise ratio. In contrast, cone pedicles utilize low affinity/high turnover NCX to rapidly lower their high [Ca2+] during light adaptation, which increases their response kinetics. Spatiotemporal fluo-3-Ca2+ imaging results support our immunocytochemical results. The clustering of cone pedicle mitochondria likely provides increased protection from Ca2+ overload and permeability transition. In summary, these novel studies reveal that several integrated cellular and subcellular components interact to regulate ATP and Ca2+ dynamics in rod and cone synaptic terminals. These results should provide a greater understanding of in vivo photoreceptor synaptic terminal exocytosis/endocytosis, Ca2+ overload and therapies for retinal degenerations. PMID:17653034

Spatiotemporal regulation of ATP and Ca2+ dynamics in vertebrate rod and cone ribbon synapses.

PubMed

Johnson, Jerry E; Perkins, Guy A; Giddabasappa, Anand; Chaney, Shawntay; Xiao, Weimin; White, Andrew D; Brown, Joshua M; Waggoner, Jenna; Ellisman, Mark H; Fox, Donald A

2007-06-15

In conventional neurons, Ca2+ enters presynaptic terminals during an action potential and its increased local concentration triggers transient exocytosis. In contrast, vertebrate photoreceptors are nonspiking neurons that maintain sustained depolarization and neurotransmitter release from ribbon synapses in darkness and produce light-dependent graded hyperpolarizing responses. Rods transmit single photon responses with high fidelity, whereas cones are less sensitive and exhibit faster response kinetics. These differences are likely due to variations in presynaptic Ca2+ dynamics. Metabolic coupling and cross-talk between mitochondria, endoplasmic reticulum (ER), plasma membrane Ca2+ ATPase (PMCA), and Na+-Ca2+ exchanger (NCX) coordinately control presynaptic ATP production and Ca2+ dynamics. The goal of our structural and functional studies was to determine the spatiotemporal regulation of ATP and Ca2+ dynamics in rod spherules and cone pedicles. Central retina tissue from C57BL/6 mice was used. Laser scanning confocal microscopy (LSCM) experiments were conducted on fixed-frozen vertical sections. Primary antibodies were selected for their tissue/cellular specificity and ability to recognize single, multiple or all splice variants of selected isoforms. Electron microscopy (EM) and 3-D electron tomography (ET) studies used our standard procedures on thin- and thick-sectioned retinas, respectively. Calibrated fluo-3-Ca2+ imaging experiments of dark- and light-adapted rod and cone terminals in retinal slices were conducted. Confocal microscopy showed that mitochondria, ER, PMCA, and NCX1 exhibited distinct retinal lamination patterns and differential distribution in photoreceptor synapses. Antibodies for three distinct mitochondrial compartments differentially labeled retinal areas with high metabolic demand: rod and cone inner segments, previously undescribed cone juxtanuclear mitochondria and the two plexiform layers. Rod spherule membranes uniformly and intensely stained for PMCA, whereas the larger cone pedicles preferentially stained for NCX1 at their active zones and PMCA near their mitochondria. EM and ET revealed that mitochondria in rod spherules and cone pedicles differed markedly in their number, location, size, volume, and total cristae surface area, and cristae junction diameter. Rod spherules had one large ovoid mitochondrion located near its active zone, whereas cone pedicles averaged five medium-sized mitochondria clustered far from their active zones. Most spherules had one ribbon synapse, whereas pedicles contained numerous ribbon synapses. Fluo-3 imaging studies revealed that during darkness rod spherules maintained a lower [Ca2+] than cone pedicles, whereas during light adaptation pedicles rapidly lowered their [Ca2+] below that observed in spherules. These findings indicate that ATP demand and mitochondrial ATP production are greater in cone pedicles than rod spherules. Rod spherules employ high affinity/low turnover PMCA and their mitochondrion to maintain a relatively low [Ca2+] in darkness, which increases their sensitivity and signal-to-noise ratio. In contrast, cone pedicles utilize low affinity/high turnover NCX to rapidly lower their high [Ca2+] during light adaptation, which increases their response kinetics. Spatiotemporal fluo-3-Ca2+ imaging results support our immunocytochemical results. The clustering of cone pedicle mitochondria likely provides increased protection from Ca2+ overload and permeability transition. In summary, these novel studies reveal that several integrated cellular and subcellular components interact to regulate ATP and Ca2+ dynamics in rod and cone synaptic terminals. These results should provide a greater understanding of in vivo photoreceptor synaptic terminal exocytosis/endocytosis, Ca2+ overload and therapies for retinal degenerations.

Terahertz artificial material based on integrated metal-rod-array for phase sensitive fluid detection.

PubMed

You, Borwen; Chen, Ching-Yu; Yu, Chin-Ping; Liu, Tze-An; Hattori, Toshiaki; Lu, Ja-Yu

2017-04-17

A terahertz artificial material composed of metal rod array is experimentally investigated on its transmission spectral property and successfully incorporated into microfluidics as a miniaturized terahertz waveguide with an extended optical-path-length for label-free fluidic sensing. Theoretical and experimental characterizations of terahertz transmission spectra show that the wave guidance along the metal rod array originates from the resonance of transverse-electric-polarized waves within the metal rod slits. The extended optical path length along three layers of metal-rod-array enables terahertz waves sufficiently overlapping the fluid molecules embedded among the rods, leading to strongly enhanced phase change by approximately one order of magnitude compared with the blank metal-parallel-plate waveguide. Based on the enhanced phase sensitivity, three kinds of colorless liquid analytes, namely, acetone, methanol, and ethanol, with different dipole moments are identified in situ using the metal-rod-array-based microfluidic sensor. The detection limit in molecular amounts of a liquid analyte is experimentally demonstrated to be less than 0.1 mmol, corresponding to 2.7 μmol/mm². The phase sensitive terahertz metal-rod-array-based sensor potentially has good adaptability in lab-chip technology for various practical applications, such as industrial toxic fluid detection and medical breath inspection.

Light adaptation does not prevent early retinal abnormalities in diabetic rats

PubMed Central

Kur, Joanna; Burian, Michael A.; Newman, Eric A.

2016-01-01

The aetiology of diabetic retinopathy (DR), the leading cause of blindness in the developed world, remains controversial. One hypothesis holds that retinal hypoxia, exacerbated by the high O2 consumption of rod photoreceptors in the dark, is a primary cause of DR. Based on this prediction we investigated whether early retinal abnormalities in streptozotocin-induced diabetic rats are alleviated by preventing the rods from dark adapting. Diabetic rats and their non-diabetic littermates were housed in a 12:12 hour light-dim light photocycle (30 lux during the day and 3 lux at night). Progression of early retinal abnormalities in diabetic rats was assessed by monitoring the ERG b-wave and oscillatory potentials, Müller cell reactive gliosis, and neuronal cell death, as assayed by TUNEL staining and retinal thickness at 6 and 12 weeks after diabetes induction. Maintaining diabetic animals in a dim-adapting light did not slow the progression of these neuronal and glial changes when compared to diabetic rats maintained in a standard 12:12 hour light-dark photocycle (30 lux during the day and 0 lux at night). Our results indicate that neuronal and glial abnormalities in early stages of diabetes are not exacerbated by rod photoreceptor O2 consumption in the dark. PMID:26852722

Mouse rods signal through gap junctions with cones

PubMed Central

Asteriti, Sabrina; Gargini, Claudia; Cangiano, Lorenzo

2014-01-01

Rod and cone photoreceptors are coupled by gap junctions (GJs), relatively large channels able to mediate both electrical and molecular communication. Despite their critical location in our visual system and evidence that they are dynamically gated for dark/light adaptation, the full impact that rod–cone GJs can have on cone function is not known. We recorded the photovoltage of mouse cones and found that the initial level of rod input increased spontaneously after obtaining intracellular access. This process allowed us to explore the underlying coupling capacity to rods, revealing that fully coupled cones acquire a striking rod-like phenotype. Calcium, a candidate mediator of the coupling process, does not appear to be involved on the cone side of the junctional channels. Our findings show that the anatomical substrate is adequate for rod–cone coupling to play an important role in vision and, possibly, in biochemical signaling among photoreceptors. DOI: http://dx.doi.org/10.7554/eLife.01386.001 PMID:24399457

Triassico: A Sphere Positioning System for Surface Studies with IBA Techniques

NASA Astrophysics Data System (ADS)

Fontana, Cristiano L.; Doyle, Barney L.

We propose here a novel device, called the Triassico, to microscopically study the entire surface of millimeter-sized spheres. The sphere dimensions can be as small as 1 mm, and the upper limit defined only by the power and by the mechanical characteristics of the motors used. Three motorized driving rods are arranged so an equilateral triangle is formed by the rod's axes, on such a triangle the sphere sits. Movement is achieved by rotating the rods with precise relative speeds and by exploiting the friction between the sphere and the rods surfaces. The sphere can be held in place by gravity or by an opposing trio of rods. By rotating the rods with specific relative angular velocities, a net torque can be exerted on the sphere which then rotates. No repositioning of the sphere or of the motors is needed to cover the full surface with the investigating tools. An algorithm was developed to position the sphere at any arbitrary polar and azimuthal angle. The algorithm minimizes the number of rotations needed by the rods, in order to efficiently select a particular position on the sphere surface. A prototype Triassico was developed for the National Ignition Facility, of the Lawrence Livermore National Laboratory (Livermore, California, USA), as a sphere manipulation apparatus for ion microbeam analysis at Sandia National Laboratories (Albuquerque, NM, USA) of Xe-doped DT inertial confinement fusion fuel spheres. Other applications span from samples orientation, ball bearing manufacturing, or jewelry.

"Teaching" an Industrial Robot To Spray

NASA Technical Reports Server (NTRS)

Evans, A. R.; Sweet, G. K.

1982-01-01

Teaching device, consisting of spacer rod or tube with three-pointed tip and line level, is used during pattern "teach-in" to make sure that robot manipulator holds spray gun perpendicular to surface to be sprayed and at right distance from it. For slanted surfaces angle adapter is added between spacer rod and line-level indicator. Angle is determined by slope of surface to be sprayed, thus allowing a perpendicular spray pattern against even slanted surfaces.

Identification of failed fuel element

DOEpatents

Fryer, Richard M.; Matlock, Robert G.

1976-06-22

A passive fission product gas trap is provided in the upper portion of each fuel subassembly in a nuclear reactor. The gas trap consists of an inverted funnel of less diameter than the subassembly having a valve at the apex thereof. An actuating rod extends upwardly from the valve through the subassembly to a point where it can be contacted by the fuel handling mechanism for the reactor. Interrogation of the subassembly for the presence of fission products is accomplished by lowering the fuel handling machine onto the subassembly to press down on the actuating rod and open the valve.

Oil well pump drive

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanford, G.A.

1980-02-12

An oil well pump drive is disclosed including a drive unit that is hydraulically actuated by a double-acting hydraulic cylinder to reciprocate vertically. An endless chain is entrained over vertically spaced sprockets carried by the unit, with one flight of the chain anchored against vertical movement and the other flight is secured to the pump polish rod so that the vertical motion imparted to the polish rod is double that hydraulically imparted to the drive unit. The polish rod load on the chain is opposed by a counterweight connected thereto by a chain extending over an elevated pulley. The outputmore » of the hydraulic pump supplying the hydraulic cylinder is cam controlled so that the motion of the drive unit is smoothly decelerated and accelerated as the unit approaches and moves from the upper and lower limits of its movement.« less

Biochemical Measurements of Free Opsin in Macular Degeneration Eyes: Examining the 11-CIS Retinal Deficiency Hypothesis of Delayed Dark Adaptation (An American Ophthalmological Society Thesis).

PubMed

Hanneken, Anne; Neikirk, Thomas; Johnson, Jennifer; Kono, Masahiro

2017-08-01

To test the hypothesis that delayed dark adaptation in patients with macular degeneration is due to an excess of free unliganded opsin (apo-opsin) and a deficiency of the visual chromophore, 11 -cis retinal, in rod outer segments. A total of 50 human autopsy eyes were harvested from donors with and without macular degeneration within 2-24 hrs. postmortem. Protocols were developed which permitted dark adaptation of normal human eyes after death and enucleation. Biochemical methods of purifying rod outer segments were optimized and the concentration of rhodopsin and apo-opsin was measured with UV-visible scanning spectroscopy. The presence of apo-opsin was calculated by measuring the difference in the rhodopsin absorption spectra before and after the addition of 11 -cis retinal. A total of 20 normal eyes and 16 eyes from donors with early, intermediate and advanced stages of macular degeneration were included in the final analysis. Dark adaptation was achieved by harvesting whole globes in low light, transferring into dark (light-proof) canisters and dissecting the globes using infrared light and image converters for visualization. Apo-opsin was readily detected in positive controls after the addition of 11 -cis retinal. Normal autopsy eyes showed no evidence of apo-opsin. Eyes with macular degeneration also showed no evidence of apo-opsin, regardless of the severity of disease. Methods have been developed to study dark adaptation in human autopsy eyes. Eyes with age-related macular degeneration do not show a deficiency of 11 -cis retinal or an excess of apo-opsin within rod outer segments.

Inhibitory masking controls the threshold sensitivity of retinal ganglion cells

PubMed Central

Pan, Feng; Toychiev, Abduqodir; Zhang, Yi; Atlasz, Tamas; Ramakrishnan, Hariharasubramanian; Roy, Kaushambi; Völgyi, Béla; Akopian, Abram

2016-01-01

Key points Retinal ganglion cells (RGCs) in dark‐adapted retinas show a range of threshold sensitivities spanning ∼3 log units of illuminance.Here, we show that the different threshold sensitivities of RGCs reflect an inhibitory mechanism that masks inputs from certain rod pathways.The masking inhibition is subserved by GABAC receptors, probably on bipolar cell axon terminals.The GABAergic masking inhibition appears independent of dopaminergic circuitry that has been shown also to affect RGC sensitivity.The results indicate a novel mechanism whereby inhibition controls the sensitivity of different cohorts of RGCs. This can limit and thereby ensure that appropriate signals are carried centrally in scotopic conditions when sensitivity rather than acuity is crucial. Abstract The responses of rod photoreceptors, which subserve dim light vision, are carried through the retina by three independent pathways. These pathways carry signals with largely different sensitivities. Retinal ganglion cells (RGCs), the output neurons of the retina, show a wide range of sensitivities in the same dark‐adapted conditions, suggesting a divergence of the rod pathways. However, this organization is not supported by the known synaptic morphology of the retina. Here, we tested an alternative idea that the rod pathways converge onto single RGCs, but inhibitory circuits selectively mask signals so that one pathway predominates. Indeed, we found that application of GABA receptor blockers increased the sensitivity of most RGCs by unmasking rod signals, which were suppressed. Our results indicate that inhibition controls the threshold responses of RGCs under dim ambient light. This mechanism can ensure that appropriate signals cross the bottleneck of the optic nerve in changing stimulus conditions. PMID:27350405

Die Fledermaus: Regarding Optokinetic Contrast Sensitivity and Light-Adaptation, Chicks Are Mice with Wings

PubMed Central

Shi, Qing; Stell, William K.

2013-01-01

Background Through adaptation, animals can function visually under an extremely broad range of light intensities. Light adaptation starts in the retina, through shifts in photoreceptor sensitivity and kinetics plus modulation of visual processing in retinal circuits. Although considerable research has been conducted on retinal adaptation in nocturnal species with rod-dominated retinas, such as the mouse, little is known about how cone-dominated avian retinas adapt to changes in mean light intensity. Methodology/Principal Findings We used the optokinetic response to characterize contrast sensitivity (CS) in the chick retina as a function of spatial frequency and temporal frequency at different mean light intensities. We found that: 1) daytime, cone-driven CS was tuned to spatial frequency; 2) nighttime, presumably rod-driven CS was tuned to temporal frequency and spatial frequency; 3) daytime, presumably cone-driven CS at threshold intensity was invariant with temporal and spatial frequency; and 4) daytime photopic CS was invariant with clock time. Conclusion/Significance Light- and dark-adaptational changes in CS were investigated comprehensively for the first time in the cone-dominated retina of an avian, diurnal species. The chick retina, like the mouse retina, adapts by using a “day/night” or “cone/rod” switch in tuning preference during changes in lighting conditions. The chick optokinetic response is an attractive model for noninvasive, behavioral studies of adaptation in retinal circuitry in health and disease. PMID:24098693

RFQ device for accelerating particles

DOEpatents

Shepard, Kenneth W.; Delayen, Jean R.

1995-01-01

A superconducting radio frequency quadrupole (RFQ) device includes four spaced elongated, linear, tubular rods disposed parallel to a charged particle beam axis, with each rod supported by two spaced tubular posts oriented radially with respect to the beam axis. The rod and post geometry of the device has four-fold rotation symmetry, lowers the frequency of the quadrupole mode below that of the dipole mode, and provides large dipole-quadrupole mode isolation to accommodate a range of mechanical tolerances. The simplicity of the geometry of the structure, which can be formed by joining eight simple T-sections, provides a high degree of mechanical stability, is insensitive to mechanical displacement, and is particularly adapted for fabrication with superconducting materials such as niobium.

Retractable Visual Indicator Assembly

NASA Technical Reports Server (NTRS)

Hackler, George R. (Inventor); Gamboa, Ronald J. (Inventor); Dominquez, Victor (Inventor)

1998-01-01

A retractable indicator assembly may be mounted on a container which transmits air through the container and removes deleterious gases with an activated charcoal medium in the container. The assembly includes: an elongate indicator housing has a chamber therein; a male adaptor with an external threads is used for sealing engagement with the container; a plug located at the upper end of the housing; a housing that includes a transparent wall portion for viewing at least a portion of the chamber; a litmus indicator, moveable by a retractable rod from a retracted position within the container to an extended position within the chamber of the housing; and an outer housing that is secured to the upper end of the rod, and protects the indicator housing while the litmus indicator is in its normally retracted position. The assembly may be manually manipulated between its extended position wherein the litmus indicator may be viewed through the transparent wall of the indicator housing, and a retracted position wherein the outer housing encloses the indicator housing and engages the exterior of the container.

Identification and Description of Geophysical Techniques.

DTIC Science & Technology

1980-11-01

electrodes are used for voltage measurements with the potentiometer. Current elec- trodes may be stainless-steel or copper rods, buried copper screens, drill...steel in a borehole, or buried metal culverts. Potential elec- trodes may be stainless steel rods or porous containers filled with copper sulfate...Granite 28-2,700 Diorite 47 Gabbro 68-2,370 Porphyry 47 Diabase 78-1,050 Basalt 680 Olivine-Diabase 2,000 1. Peridotite 12,500 I (1)Adapted from C. A

Upper Atmosphere Research Report Number 21. Summary of Upper Atmosphere Rocket Research Firings

DTIC Science & Technology

1954-02-01

computer . The sky screens are essentially theodolites which view the rocket through a pair of - crossed rods which are driven closed by an electric motor...positions are electrically measured and fed into a computer . The computer continously predicts the point of impact of the rocket 411 were its thrust...Without such equipment it is neces- sary to rely on optical ’fixes’, sound ranging, or the Impact Point Computer to provide such information. In the early

Thresholds and noise limitations of colour vision in dim light.

PubMed

Kelber, Almut; Yovanovich, Carola; Olsson, Peter

2017-04-05

Colour discrimination is based on opponent photoreceptor interactions, and limited by receptor noise. In dim light, photon shot noise impairs colour vision, and in vertebrates, the absolute threshold of colour vision is set by dark noise in cones. Nocturnal insects (e.g. moths and nocturnal bees) and vertebrates lacking rods (geckos) have adaptations to reduce receptor noise and use chromatic vision even in very dim light. In contrast, vertebrates with duplex retinae use colour-blind rod vision when noisy cone signals become unreliable, and their transition from cone- to rod-based vision is marked by the Purkinje shift. Rod-cone interactions have not been shown to improve colour vision in dim light, but may contribute to colour vision in mesopic light intensities. Frogs and toads that have two types of rods use opponent signals from these rods to control phototaxis even at their visual threshold. However, for tasks such as prey or mate choice, their colour discrimination abilities fail at brighter light intensities, similar to other vertebrates, probably limited by the dark noise in cones.This article is part of the themed issue 'Vision in dim light'. © 2017 The Author(s).

Melanopsin changes in neonatal albino rat independent of rods and cones.

PubMed

Hannibal, Jens; Georg, Birgitte; Fahrenkrug, Jan

2007-01-08

Intrinsically photosensitive retinal ganglion cells employ the photopigment melanopsin and provide light information to brain areas responsible for the regulation of circadian rhythms. The expression of melanopsin is regulated by environmental illumination, but it remains to be clarified whether the rods and cones are involved. Here, we examined the influence of 5 days of constant light and dark conditions on melanopsin mRNA and protein expression in newborn albino rats, in which functional rods and cones have not yet been developed. We found that the melanopsin mRNA level was unaffected, whereas the melanopsin protein level was more than two-fold higher in the darkness-adapted group than in pups raised in constant light. In pups raised during 12 : 12 h light/dark cycles, the melanopsin protein level was significantly higher during the day than at night. Our findings indicate that melanopsin protein changes are independent of input from the rods and cones.

Deformation of a soft helical filament in an axial flow at low Reynolds number.

PubMed

Jawed, Mohammad K; Reis, Pedro M

2016-02-14

We perform a numerical investigation of the deformation of a rotating helical filament subjected to an axial flow, under low Reynolds number conditions, motivated by the propulsion of bacteria using helical flagella. Given its slenderness, the helical rod is intrinsically soft and deforms due to the interplay between elastic forces and hydrodynamic loading. We make use of a previously developed and experimentally validated computational tool framework that models the elasticity of the filament using the discrete elastic rod method and the fluid forces are treated using Lighthill's slender body theory. Under axial flow, and in the absence of rotation, the initially helical rod is extended. Above a critical flow speed its configuration comprises a straight portion connected to a localized helix near the free end. When the rod is also rotated about its helical axis, propulsion is only possible in a finite range of angular velocity, with an upper bound that is limited by buckling of the soft helix arising due to viscous stresses. A systematic exploration of the parameter space allows us to quantify regimes for successful propulsion for a number of specific bacteria.

Cat colour vision: one cone process or several?

PubMed Central

Daw, N. W.; Pearlman, A. L.

1969-01-01

1. Peripheral mechanisms that might contribute to colour vision in the cat have been investigated by recording from single units in the lateral geniculate and optic tract. Evidence is presented that the input to these cells comes from a single class of cones with a single spectral sensitivity. 2. In cats with pupils dilated a background level of 10-30 cd/m2 was sufficient to saturate the rod system for all units. When the rods were saturated, the spectral sensitivity of all units peaked at 556 nm; this was true both for centre and periphery of the receptive field. The spectral sensitivity curve was slightly narrower than the Dartnall nomogram. It could not be shifted by chromatic adaptation with red, green, blue or yellow backgrounds. 3. In the mesopic range (0·1-10 cd/m2), the threshold could be predicted in terms of two mechanisms, a cone mechanism with spectral sensitivity peaking at 556 nm, and a rod mechanism with spectral sensitivity at 500 nm. The mechanisms were separated and their increment threshold curves measured by testing with one colour against a background of another colour. All units had input from both rods and cones. The changeover from rods to cones occurred at the same level of adaptation in both centre and periphery of the receptive field. Threshold for the cones was between 0·04 and 0·25 cd/m2 with the pupil dilated, for a spot covering the centre of the receptive field. 4. None of the results was found to vary between lateral geniculate and optic tract, with layer in the lateral geniculate, or with distance from area centralis in the visual field. 5. The lack of evidence for more than one cone type suggests that colour discrimination in the cat may be a phenomenon of mesopic vision, based on differences in spectral sensitivity of the rods and a single class of cones. PMID:5767891

Low aqueous solubility of 11-cis-retinal limits the rate of pigment formation and dark adaptation in salamander rods.

PubMed

Frederiksen, Rikard; Boyer, Nicholas P; Nickle, Benjamin; Chakrabarti, Kalyan S; Koutalos, Yiannis; Crouch, Rosalie K; Oprian, Daniel; Cornwall, M Carter

2012-06-01

We report experiments designed to test the hypothesis that the aqueous solubility of 11-cis-retinoids plays a significant role in the rate of visual pigment regeneration. Therefore, we have compared the aqueous solubility and the partition coefficients in photoreceptor membranes of native 11-cis-retinal and an analogue retinoid, 11-cis 4-OH retinal, which has a significantly higher solubility in aqueous medium. We have then correlated these parameters with the rates of pigment regeneration and sensitivity recovery that are observed when bleached intact salamander rod photoreceptors are treated with physiological solutions containing these retinoids. We report the following results: (a) 11-cis 4-OH retinal is more soluble in aqueous buffer than 11-cis-retinal. (b) Both 11-cis-retinal and 11-cis 4-OH retinal have extremely high partition coefficients in photoreceptor membranes, though the partition coefficient of 11-cis-retinal is roughly 50-fold greater than that of 11-cis 4-OH retinal. (c) Intact bleached isolated rods treated with solutions containing equimolar amounts of 11-cis-retinal or 11-cis 4-OH retinal form functional visual pigments that promote full recovery of dark current, sensitivity, and response kinetics. However, rods treated with 11-cis 4-OH retinal regenerated on average fivefold faster than rods treated with 11-cis-retinal. (d) Pigment regeneration from recombinant and wild-type opsin in solution is slower when treated with 11-cis 4-OH retinal than with 11-cis-retinal. Based on these observations, we propose a model in which aqueous solubility of cis-retinoids within the photoreceptor cytosol can place a limit on the rate of visual pigment regeneration in vertebrate photoreceptors. We conclude that the cytosolic gap between the plasma membrane and the disk membranes presents a bottleneck for retinoid flux that results in slowed pigment regeneration and dark adaptation in rod photoreceptors.

Fretting wear behaviors of a dual-cooled nuclear fuel rod under a simulated rod vibration

NASA Astrophysics Data System (ADS)

Lee, Young-Ho; Kim, Hyung-Kyu; Kang, Heung-Seok; Yoon, Kyung-Ho; Kim, Jae-Yong; Lee, Kang-Hee

2012-06-01

Recently, a dual-cooled fuel (i.e., annular fuel) that is compatible with current operating PWR plants has been proposed in order to realize both a considerable amount of power uprating and an increase of safety margins. As the design concept should be compatible with current operating PWR plants, however, it shows a narrow gap between the fuel rods when compared with current solid nuclear fuel arrays and needs to modify the spacer grid shapes and their positions. In this study, fretting wear tests have been performed to evaluate the wear resistance of a dual-cooled fuel by using a proposed spring and dimple of spacer grids that have a cantilever type and hemispherical shape, respectively. As a result, the wear volume of the spring specimen gradually increases as the contact condition is changed from a certain gap, just contact to positive force. However, in the dimple specimen, just contact condition shows a large wear volume. In addition, a circular rod motion at upper region of contact surface is gradually increased and its diametric size depends on the wear depth increase. Based on the test results, the fretting wear resistance of the proposed spring and dimple is analyzed by comparing the wear measurement results and rod motion in detail.

Evolutionary transformation of rod photoreceptors in the all-cone retina of a diurnal garter snake

PubMed Central

Schott, Ryan K.; Müller, Johannes; Yang, Clement G. Y.; Bhattacharyya, Nihar; Chan, Natalie; Xu, Mengshu; Morrow, James M.; Ghenu, Ana-Hermina; Loew, Ellis R.; Tropepe, Vincent; Chang, Belinda S. W.

2016-01-01

Vertebrate retinas are generally composed of rod (dim-light) and cone (bright-light) photoreceptors with distinct morphologies that evolved as adaptations to nocturnal/crepuscular and diurnal light environments. Over 70 years ago, the “transmutation” theory was proposed to explain some of the rare exceptions in which a photoreceptor type is missing, suggesting that photoreceptors could evolutionarily transition between cell types. Although studies have shown support for this theory in nocturnal geckos, the origins of all-cone retinas, such as those found in diurnal colubrid snakes, remain a mystery. Here we investigate the evolutionary fate of the rods in a diurnal garter snake and test two competing hypotheses: (i) that the rods, and their corresponding molecular machinery, were lost or (ii) that the rods were evolutionarily modified to resemble, and function, as cones. Using multiple approaches, we find evidence for a functional and unusually blue-shifted rhodopsin that is expressed in small single “cones.” Moreover, these cones express rod transducin and have rod ultrastructural features, providing strong support for the hypothesis that they are not true cones, as previously thought, but rather are modified rods. Several intriguing features of garter snake rhodopsin are suggestive of a more cone-like function. We propose that these cone-like rods may have evolved to regain spectral sensitivity and chromatic discrimination as a result of ancestral losses of middle-wavelength cone opsins in early snake evolution. This study illustrates how sensory evolution can be shaped not only by environmental constraints but also by historical contingency in forming new cell types with convergent functionality. PMID:26715746

Tauroursodeoxycholic acid preserves photoreceptor structure and function in the rd10 mouse through post-natal day 30

PubMed Central

Phillips, M. Joe; Walker, Tiffany A.; Choi, Hee-young; Faulkner, Amanda E.; Kim, Moon K.; Sidney, Sheree; Boyd, Amber; Nickerson, John M.; Boatright, Jeffrey H.; Pardue, Machelle T.

2008-01-01

Purpose Retinitis Pigmentosa (RP) is a progressive neurodegenerative disease resulting in blindness for which there is no current treatment. While the members of the family of RP diseases differ in etiology, their outcomes are the same: apoptosis of rods followed by cones. Recently, the bile acid, tauroursodeoxycholic acid (TUDCA), has been shown to have anti-apoptotic properties in neurodegenerative diseases, including those of the retina. In this study we examine the efficacy of TUDCA on preserving rod and cone function and morphology at post-natal day 30 (P30) in the rd10 mouse, a model of RP. Methods Wild-type C57BL/6J and rd10 mice were systemically injected with TUDCA (500 mg/kg) every three days from P6-P30 and compared to vehicle (0.15M NaHCO3). At P30, retinal function was measured with electroretinography (ERG) and morphological preservation of the rods and cones assessed with immunohistochemistry. Results Dark-adapted ERG responses were two-fold greater in rd10 mice treated with TUDCA compared to vehicle, while light-adapted responses were two-fold larger in TUDCA-treated mice compared to controls, at the brightest ERG flash intensities. TUDCA-treated rd10 retinas had five-fold more photoreceptors than vehicle-treated. TUDCA treatments did not alter retinal function or morphology of wild-type mice when administered to age-matched mice. Conclusions TUDCA is efficacious and safe in preserving vision in the rd10 mouse model of RP when treated between P6 and P30. At P30, a developmental stage at which nearly all rods are absent in the rd10 mouse model of RP, TUDCA treatment preserved both rod and cone function and greatly preserved overall photoreceptor numbers. PMID:18436848

Thresholds and noise limitations of colour vision in dim light

PubMed Central

Yovanovich, Carola

2017-01-01

Colour discrimination is based on opponent photoreceptor interactions, and limited by receptor noise. In dim light, photon shot noise impairs colour vision, and in vertebrates, the absolute threshold of colour vision is set by dark noise in cones. Nocturnal insects (e.g. moths and nocturnal bees) and vertebrates lacking rods (geckos) have adaptations to reduce receptor noise and use chromatic vision even in very dim light. In contrast, vertebrates with duplex retinae use colour-blind rod vision when noisy cone signals become unreliable, and their transition from cone- to rod-based vision is marked by the Purkinje shift. Rod–cone interactions have not been shown to improve colour vision in dim light, but may contribute to colour vision in mesopic light intensities. Frogs and toads that have two types of rods use opponent signals from these rods to control phototaxis even at their visual threshold. However, for tasks such as prey or mate choice, their colour discrimination abilities fail at brighter light intensities, similar to other vertebrates, probably limited by the dark noise in cones. This article is part of the themed issue 'Vision in dim light’. PMID:28193810

Behavioural and physiological limits to vision in mammals

PubMed Central

Field, Greg D.

2017-01-01

Human vision is exquisitely sensitive—a dark-adapted observer is capable of reliably detecting the absorption of a few quanta of light. Such sensitivity requires that the sensory receptors of the retina, rod photoreceptors, generate a reliable signal when single photons are absorbed. In addition, the retina must be able to extract this information and relay it to higher visual centres under conditions where very few rods signal single-photon responses while the majority generate only noise. Critical to signal transmission are mechanistic optimizations within rods and their dedicated retinal circuits that enhance the discriminability of single-photon responses by mitigating photoreceptor and synaptic noise. We describe behavioural experiments over the past century that have led to the appreciation of high sensitivity near absolute visual threshold. We further consider mechanisms within rod photoreceptors and dedicated rod circuits that act to extract single-photon responses from cellular noise. We highlight how these studies have shaped our understanding of brain function and point out several unresolved questions in the processing of light near the visual threshold. This article is part of the themed issue ‘Vision in dim light’. PMID:28193817

Experience using individually supplied heater rods in critical power testing of advanced BWR fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Majed, M.; Morback, G.; Wiman, P.

1995-09-01

The ABB Atom FRIGG loop located in Vasteras Sweden has during the last six years given a large experience of critical power measurements for BWR fuel designs using indirectly heated rods with individual power supply. The loop was built in the sixties and designed for maximum 100 bar pressure. Testing up to the mid eighties was performed with directly heated rods using a 9 MW, 80 kA power supply. Providing test data to develop critical power correlations for BWR fuel assemblies requires testing with many radial power distributions over the full range of hydraulic conditions. Indirectly heated rods give largemore » advantages for the testing procedure, particularly convenient for variation of individual rod power. A test method being used at Stern Laboratories (formerly Westinghouse Canada) since the early sixties, allows one fuel assembly to simulate all required radial power distributions. This technique requires reliable indirectly heated rods with independently controlled power supplies and uses insulated electric fuel rod simulators with built-in instrumentation. The FRIGG loop was adapted to this system in 1987. A 4MW power supply with 10 individual units was then installed, and has since been used for testing 24 and 25 rod bundles simulating one subbundle of SVEA-96/100 type fuel assemblies. The experience with the system is very good, as being presented, and it is selected also for a planned upgrading of the facility to 15 MW.« less

Apparatuses for prestressing rod-type specimens in torsion for in-situ passive fracture toughness testing in an extremely high-pressure environment of hydrogen

DOEpatents

Wang, Jy-an [Oak Ridge, TN; Liu, Ken C [Oak Ridge, TN; Feng, Zhili [Knoxville, TN

2012-05-15

An in-situ specimen fixture particularly adapted for prestressing rod-type SNTT-type specimens comprising a tube and end cap wherein the specimen is secured at one end to the tube, and at the opposite end to the end cap. The end cap is rotatable relative to the tube, and may be fixedly secured for creating a torsional force prestressing the specimen enclosed within the tube.

RFQ device for accelerating particles

DOEpatents

Shepard, K.W.; Delayen, J.R.

1995-06-06

A superconducting radio frequency quadrupole (RFQ) device includes four spaced elongated, linear, tubular rods disposed parallel to a charged particle beam axis, with each rod supported by two spaced tubular posts oriented radially with respect to the beam axis. The rod and post geometry of the device has four-fold rotation symmetry, lowers the frequency of the quadrupole mode below that of the dipole mode, and provides large dipole-quadrupole mode isolation to accommodate a range of mechanical tolerances. The simplicity of the geometry of the structure, which can be formed by joining eight simple T-sections, provides a high degree of mechanical stability, is insensitive to mechanical displacement, and is particularly adapted for fabrication with superconducting materials such as niobium. 5 figs.

Sports Adaptations for Unilateral and Bilateral Upper-Limb Amputees: Archery/Badminton/Baseball/Softball/Bowling/Golf/Table Tennis.

ERIC Educational Resources Information Center

Cowart, Jim

1979-01-01

The booklet discusses sports adaptations for unilateral and bilateral upper limb amputees. Designs for adapted equipment are illustrated and information on adaptations are described for archery (including an archery release aid and a stationary bow holder); badminton (serving tray); baseball/softball (adaptations for catching, throwing, and…

cis Retinol oxidation regulates photoreceptor access to the retina visual cycle and cone pigment regeneration

PubMed Central

Sato, Shinya

2016-01-01

Key points This study explores the nature of the cis retinol that Müller cells in the retina provide to cones for the regeneration of their visual pigment.We report that the retina visual cycle provides cones exclusively with 11‐cis chromophore in both salamander and mouse and show that this selectivity is dependent on the 11‐cis‐specific cellular retinaldehyde binding protein (CRALBP) present in Müller cells.Even though salamander blue cones and green rods share the same visual pigment, only blue cones but not green rods are able to dark‐adapt in the retina following a bleach and to use exogenous 9‐cis retinol for pigment regeneration, suggesting that access to the retina visual cycle is cone‐specific and pigment‐independent.Our results show that the retina produces 11‐cis retinol that can be oxidized and used for pigment regeneration and dark adaptation selectively in cones and not in rods. Abstract Chromophore supply by the retinal Müller cells (retina visual cycle) supports the efficient pigment regeneration required for cone photoreceptor function in bright light. Surprisingly, a large fraction of the chromophore produced by dihydroceramide desaturase‐1, the putative all‐trans retinol isomerase in Müller cells, appears to be 9‐cis retinol. In contrast, the canonical retinal pigment epithelium (RPE) visual cycle produces exclusively 11‐cis retinal. Here, we used the different absorption spectra of 9‐cis and 11‐cis pigments to identify the isoform of the chromophore produced by the visual cycle of the intact retina. We found that the spectral sensitivity of salamander and mouse cones dark‐adapted in the isolated retina (with only the retina visual cycle) was similar to that of cones dark‐adapted in the intact eye (with both the RPE and retina visual cycles) and consistent with pure 11‐cis pigment composition. However, in mice lacking the cellular retinaldehyde binding protein (CRALBP), cone spectral sensitivity contained a substantial 9‐cis component. Thus, the retina visual cycle provides cones exclusively with 11‐cis chromophore and this process is mediated by the 11‐cis selective CRALBP in Müller cells. Finally, despite sharing the same pigment, salamander blue cones, but not green rods, recovered their sensitivity in the isolated retina. Exogenous 9‐cis retinol produced robust sensitivity recovery in bleached red and blue cones but not in red and green rods, suggesting that cis retinol oxidation restricts access to the retina visual cycle to cones. PMID:27385534

Genomic evidence for rod monochromacy in sloths and armadillos suggests early subterranean history for Xenarthra

PubMed Central

Emerling, Christopher A.; Springer, Mark S.

2015-01-01

Rod monochromacy is a rare condition in vertebrates characterized by the absence of cone photoreceptor cells. The resulting phenotype is colourblindness and low acuity vision in dim-light and blindness in bright-light conditions. Early reports of xenarthrans (armadillos, sloths and anteaters) suggest that they are rod monochromats, but this has not been tested with genomic data. We searched the genomes of Dasypus novemcinctus (nine-banded armadillo), Choloepus hoffmanni (Hoffmann's two-toed sloth) and Mylodon darwinii (extinct ground sloth) for retinal photoreceptor genes and examined them for inactivating mutations. We performed PCR and Sanger sequencing on cone phototransduction genes of 10 additional xenarthrans to test for shared inactivating mutations and estimated the timing of inactivation for photoreceptor pseudogenes. We concluded that a stem xenarthran became an long-wavelength sensitive-cone monochromat following a missense mutation at a critical residue in SWS1, and a stem cingulate (armadillos, glyptodonts and pampatheres) and stem pilosan (sloths and anteaters) independently acquired rod monochromacy early in their evolutionary history following the inactivation of LWS and PDE6C, respectively. We hypothesize that rod monochromacy in armadillos and pilosans evolved as an adaptation to a subterranean habitat in the early history of Xenarthra. The presence of rod monochromacy has major implications for understanding xenarthran behavioural ecology and evolution. PMID:25540280

Detection of briefly flashed sine-gratings in dark-adapted vision.

PubMed

Hofmann, M I; Barnes, C S; Hallett, P E

1990-01-01

Scotopic contrast sensitivity was measured near 20 deg retinal eccentricity for briefly flashed (10 or 20 msec) sine-wave gratings presented in darkness to dark-adapted subjects. For very low spatial frequencies (0.2-0.5 c/deg), curves of contrast sensitivity vs luminous energy show evidence of a low rod plateau and a high scotopic region, with an intervening transition at around -2 to -2.5 log scot td sec. Similar measurements made using long flashed or flickering gratings do not show a plateau. The results suggest that vision in the low rod region is impaired for brief flashes. For the briefly flashed stimuli, curves of contrast sensitivity versus spatial frequency in the low region were best fit by simple Gaussian functions with a variable centre size (sigma c = 0.5----0.25 deg), size decreasing with increasing flash energy. Difference-of-Gaussian functions with constant centre size (sigma c = 0.25 deg) provided the best fit in the high region. Overt input from the cones and grating area artefacts are excluded by appropriate tests. Calculation of photon flux into the receptive field centres suggests that signal compression in P alpha ganglion cells contributes to the low rod plateau.

Case of adult-onset neuronal intranuclear hyaline inclusion disease with negative electroretinogram.

PubMed

Yamada, Wataru; Takekoshi, Akira; Ishida, Kyoko; Mochizuki, Kiyofumi; Sone, Jun; Sobue, Gen; Hayashi, Yuichi; Inuzuka, Takashi; Miyake, Yozo

2017-06-01

To report the findings in a 72-year-old man with neuronal intranuclear hyaline inclusion disease (NIHID) with the negative-type electroretinogram (ERG) and without night blindness. Standard ophthalmological examinations including the medical history, measurements of the best-corrected visual acuity and intraocular pressures, slit-lamp biomicroscopy, ophthalmoscopy, spectral-domain optical coherence tomography, fundus autofluorescence, and perimetry were performed. In addition, neurological and electrophysiological examinations were performed. NIHID was confirmed by skin biopsy. The ophthalmologic examinations revealed sluggish pupillary reflexes without visual disturbances and retinal abnormalities. The amplitudes of the dark-adapted 0.01 ERG was absent, and light-adapted 3 ERG and light-adapted 30 Hz flicker ERG were reduced in amplitude and delayed in implicit time. The rod system was more severely affected than the cone system, indicating that NIHID is classified as one of rod-cone dysfunction syndrome. The dark-adapted 3 ERG consisted of a markedly reduced b-wave with larger a-wave (negative ERG), but the amplitude of a-wave was smaller than normal. Since the ophthalmoscopical findings and the subjective visual functions may be essentially normal, the characteristic ERG abnormalities can be an important findings in adult-onset NIHID without night blindness.

Driving ability following upper limb amputation.

PubMed

Burger, Helena; Marincek, Crt

2013-10-01

In the existing literature, there is scarce information about subjects with upper limb amputation and driving. The aim of this study was to find out how frequently subjects following upper limb amputation have problems when driving; most frequently proposed adaptations and, when possible, factors that influence driving ability. Retrospective clinical study. Medical records were reviewed of all subjects following upper limb amputation who had been amputated in the last 5 years and those with congenital upper limb deficiency who in the last 5 years turned 17. Out of 37 subjects, 7 did not attend the clinic for assessment of driving abilities. They were significantly older at the time of the amputation (p < 0.001). To the remaining 30 who attended driving assessment, zero to four car adaptations (two on average) were proposed. There were no correlations between the number of suggested car adaptations and the age at the time of the amputation, amputation level, education and severity of phantom limb pain. Type of prosthesis also did not influence the number of car adaptations. Most people following upper limb amputation need at least one car adaptation for safe driving.

Modeling photo-bleaching kinetics to map local variations in rod rhodopsin density

NASA Astrophysics Data System (ADS)

Ehler, M.; Dobrosotskaya, J.; King, E. J.; Czaja, W.; Bonner, R. F.

2011-03-01

Localized rod photoreceptor and rhodopsin losses have been observed in post mortem histology both in normal aging and in age-related maculopathy. We propose to noninvasively map local rod rhodopsin density through analysis of the brightening of the underlying lipofuscin autofluorescence (LAF) in confocal scanning laser ophthalmoscopy (cSLO) imaging sequences starting in the dark adapted eye. The detected LAF increases as rhodopsin is bleached (time constant ~ 25sec) by the average retinal irradiance of the cSLO 488nm laser beam. We fit parameters of analytical expressions for the kinetics of rhodopsin bleaching that Lamb validated using electroretinogram recordings in human. By performing localized (~ 100μm) kinetic analysis, we create high resolution maps of the rhodopsin density. This new noninvasive imaging and analysis approach appears well-suited for measuring localized changes in the rod photoreceptors and correlating them at high spatial resolution with localized pathological changes of the retinal pigment epithelium (RPE) seen in steady-state LAF images.

Histological evidence for a supraspinous ligament in sauropod dinosaurs

PubMed Central

Cerda, Ignacio A.; Casal, Gabriel A.; Martinez, Rubén D.; Ibiricu, Lucio M.

2015-01-01

Supraspinous ossified rods have been reported in the sacra of some derived sauropod dinosaurs. Although different hypotheses have been proposed to explain the origin of this structure, histological evidence has never been provided to support or reject any of them. In order to establish its origin, we analyse and characterize the microstructure of the supraspinous rod of two sauropod dinosaurs from the Upper Cretaceous of Argentina. The supraspinous ossified rod is almost entirely formed by dense Haversian bone. Remains of primary bone consist entirely of an avascular tissue composed of two types of fibre-like structures, which are coarse and longitudinally (parallel to the main axis of the element) oriented. These structures are differentiated on the basis of their optical properties under polarized light. Very thin fibrous strands are also observed in some regions. These small fibres are all oriented parallel to one another but perpendicular to the element main axis. Histological features of the primary bone tissue indicate that the sacral supraspinous rod corresponds to an ossified supraspinous ligament. The formation of this structure appears to have been a non-pathological metaplastic ossification, possibly induced by the continuous tensile forces applied to the element. PMID:26587248

Six-degree-of-freedom multi-axes positioning apparatus

DOEpatents

Bieg, L.F.X.

1999-05-11

A six-degree-of-freedom multi-axes positioning apparatus is comprised of a geometry of six independent angle connectors. Each angle connector connects two fixed length rods to a pivot on one of two opposing platforms. The combination of an angle connector, at least two pivots and at least two rods having free ends connected to the pivots comprises a leg assembly. The spatial location of the upper platform is changed in relation to the lower platform by angular changes within each angle connector. This angular change results in degrees of motion within the apparatus defined as X, Y, Z, Tip, Tilt, and Rotation, or a combination of the above. This invention is known as a ROTOPOD. 9 figs.

Six-degree-of-freedom multi-axes positioning apparatus

DOEpatents

Bieg, Lothar F. X.

1999-01-01

A six-degree-of-freedom multi-axes positioning apparatus is comprised of a geometry of six independent angle connectors. Each angle connector connects two fixed length rods to a pivot on one of two opposing platforms. The combination of an angle connector, at least two pivots and at least two rods having free ends connected to the pivots comprises a leg assembly. The spatial location of the upper platform is changed in relation to the lower platform by angular changes within each angle connector. This angular change results in degrees of motion within the apparatus defined as X, Y, Z, Tip, Tilt, and Rotation, or a combination of the above. This invention is known as a ROTOPOD.

Night Vision Manual for the Flight Surgeon

DTIC Science & Technology

1992-08-01

may cause night blindness are glaucoma, progressive cone/rod dystrophies (e.g., retinitis pigmentosa , Stargardt’s disease), drug toxicity (e.g...Alabama, July 1989. 38. Berson EL, Rabin AR, Mehaffey L. Advances in night vision twchnology: A pocketscope for patients with retinitis pigmentosa ... retinal sensitivity to dim light. Regeneration of the photopigments occurs during dark adaptation. The fully dark-adapted eye, in which photopigment

Dim light adaptation attenuates acute melatonin suppression in humans.

PubMed

Jasser, Samar A; Hanifin, John P; Rollag, Mark D; Brainard, George C

2006-10-01

Abstract Studies in rodents with retinal degeneration indicated that neither the rod nor the cone photoreceptors obligatorily participate in circadian responses to light, including melatonin suppression and photoperiodic response. Yet there is a residual phase-shifting response in melanopsin knockout mice, which suggests an alternate or redundant means for light input to the SCN of the hypothalamus. The findings of Aggelopoulos and Meissl suggest a complex, dynamic interrelationship between the classic visual photoreceptors and SCN cell sensitivity to light stimuli, relative to various adaptive lighting conditions. These studies raised the possibility that the phototransductive physiology of the retinohypothalamic tract in humans might be modulated by the visual rod and cone photoreceptors. The aim of the following two-part study was to test the hypothesis that dim light adaptation will dampen the subsequent suppression of melatonin by monochromatic light in healthy human subjects. Each experiment included 5 female and 3 male human subjects between the ages of 18 and 30 years, with normal color vision. Dim white light and darkness adaptation exposures occurred between midnight and 0200 h, and a full-field 460-nm light exposure subsequently occurred between 0200 and 0330-h for each adaptation condition, at 2 different intensities. Plasma samples were drawn following the 2-h adaptation, as well as after the 460-nm monochromatic light exposure, and melatonin was measured by radioimmunoassay. Comparison of melatonin suppression responses to monochromatic light in both studies revealed a loss of significant suppression after dim white light adaptation compared with dark adaptation (p < 0.04 and p < 0.01). These findings indicate that the activity of the novel circadian photoreceptive system in humans is subject to subthreshold modulation of its sensitivity to subsequent monochromatic light exposure, varying with the conditions of light adaptation prior to exposure.

Functional Optical Coherence Tomography Enables In Vivo Physiological Assessment of Retinal Rod and Cone Photoreceptors

PubMed Central

Zhang, Qiuxiang; Lu, Rongwen; Wang, Benquan; Messinger, Jeffrey D.; Curcio, Christine A.; Yao, Xincheng

2015-01-01

Transient intrinsic optical signal (IOS) changes have been observed in retinal photoreceptors, suggesting a unique biomarker for eye disease detection. However, clinical deployment of IOS imaging is challenging due to unclear IOS sources and limited signal-to-noise ratios (SNRs). Here, by developing high spatiotemporal resolution optical coherence tomography (OCT) and applying an adaptive algorithm for IOS processing, we were able to record robust IOSs from single-pass measurements. Transient IOSs, which might reflect an early stage of light phototransduction, are consistently observed in the photoreceptor outer segment almost immediately (<4 ms) after retinal stimulation. Comparative studies of dark- and light-adapted retinas have demonstrated the feasibility of functional OCT mapping of rod and cone photoreceptors, promising a new method for early disease detection and improved treatment of diseases such as age-related macular degeneration (AMD) and other eye diseases that can cause photoreceptor damage. PMID:25901915

Ribbon synapses compute temporal contrast and encode luminance in retinal rod bipolar cells

PubMed Central

Oesch, Nicholas W.; Diamond, Jeffrey S.

2011-01-01

Contrast is computed throughout the nervous system to encode changing inputs efficiently. The retina encodes luminance and contrast over a wide range of visual conditions and so must adapt its responses to maintain sensitivity and avoid saturation. Here we show how one type of adaptation allows individual synapses to compute contrast and encode luminance in biphasic responses to step changes in light levels. Light-evoked depletion of the readily releasable vesicle pool (RRP) at rod bipolar cell (RBC) ribbon synapses in rat retina limits the dynamic range available to encode transient but not sustained responses, thereby allowing the transient and sustained components of release to compute temporal contrast and encode mean light levels, respectively. A release/replenishment model shows that a single, homogeneous pool of synaptic vesicles is sufficient to generate this behavior and reveals that the dominant mechanism shaping the biphasic contrast/luminance response is the partial depletion of the RRP. PMID:22019730

Forwardly-placed firearm fire control assembly

DOEpatents

Frickey, Steven J.

2001-12-22

A firearm fire control assembly for disposition in a forwardly placed support-hand operative relationship within a firearm having a combination of a firing pin and a firearm hammer adapted to engage and fire a cartridge, a sear assembly to alternately engage and disengage the combination of the firearm hammer and firing pin, and a trigger assembly including a movable trigger mechanism that is operable to engage the sear assembly to cause the firearm hammer firing pin combination to fire the firearm, a fire control assembly including a fire control depression member and a fire control rod operably connected to the depression member, and being positioned in a forward disposition disposed within a forestock of the firearm, and the depression member adapted to be operably engaged and depressed by the user's conventional forwardly placed support hand to maneuver the fire control rod to provide firing control of the firing of the firearm.

Metal-to-ceramic attachment device

DOEpatents

Pavelka, Edwin A.; Grindstaff, Quirinus G.; Scheppele, Stuart E.

1985-01-01

A metal-to-ceramic fastening device is disclosed for securing a metal member to a ceramic member with respective confronting surfaces thereon clamped together, comprising a threaded bolt adapted to extend through a bolt hole in the metal member and into an aligned opening in the ceramic member, a rod nut threadedly receiving the bolt and adapted to span the opening in the ceramic member, and a pressure limiting member received on the bolt between the nut and the confronting surface of the metal member for limiting the movement of the nut toward the metal member when the bolt is tightened, so as to limit the pressure applied by the nut to the ceramic member to avoid damage thereto. The fastening device also prevents damage to the ceramic member due to thermal stresses. The pressure limiting member may have a shallow dish-shaped depression facing the rod nut to assist in accommodating thermal stresses.

Functional Optical Coherence Tomography Enables In Vivo Physiological Assessment of Retinal Rod and Cone Photoreceptors

NASA Astrophysics Data System (ADS)

Zhang, Qiuxiang; Lu, Rongwen; Wang, Benquan; Messinger, Jeffrey D.; Curcio, Christine A.; Yao, Xincheng

2015-04-01

Transient intrinsic optical signal (IOS) changes have been observed in retinal photoreceptors, suggesting a unique biomarker for eye disease detection. However, clinical deployment of IOS imaging is challenging due to unclear IOS sources and limited signal-to-noise ratios (SNRs). Here, by developing high spatiotemporal resolution optical coherence tomography (OCT) and applying an adaptive algorithm for IOS processing, we were able to record robust IOSs from single-pass measurements. Transient IOSs, which might reflect an early stage of light phototransduction, are consistently observed in the photoreceptor outer segment almost immediately (<4 ms) after retinal stimulation. Comparative studies of dark- and light-adapted retinas have demonstrated the feasibility of functional OCT mapping of rod and cone photoreceptors, promising a new method for early disease detection and improved treatment of diseases such as age-related macular degeneration (AMD) and other eye diseases that can cause photoreceptor damage.

Adaptive control method for core power control in TRIGA Mark II reactor

NASA Astrophysics Data System (ADS)

Sabri Minhat, Mohd; Selamat, Hazlina; Subha, Nurul Adilla Mohd

2018-01-01

The 1MWth Reactor TRIGA PUSPATI (RTP) Mark II type has undergone more than 35 years of operation. The existing core power control uses feedback control algorithm (FCA). It is challenging to keep the core power stable at the desired value within acceptable error bands to meet the safety demand of RTP due to the sensitivity of nuclear research reactor operation. Currently, the system is not satisfied with power tracking performance and can be improved. Therefore, a new design core power control is very important to improve the current performance in tracking and regulate reactor power by control the movement of control rods. In this paper, the adaptive controller and focus on Model Reference Adaptive Control (MRAC) and Self-Tuning Control (STC) were applied to the control of the core power. The model for core power control was based on mathematical models of the reactor core, adaptive controller model, and control rods selection programming. The mathematical models of the reactor core were based on point kinetics model, thermal hydraulic models, and reactivity models. The adaptive control model was presented using Lyapunov method to ensure stable close loop system and STC Generalised Minimum Variance (GMV) Controller was not necessary to know the exact plant transfer function in designing the core power control. The performance between proposed adaptive control and FCA will be compared via computer simulation and analysed the simulation results manifest the effectiveness and the good performance of the proposed control method for core power control.

Apparatus for tensile testing plate-type ceramic specimens

DOEpatents

Liu, K.C.

1993-08-24

Apparatus is described for gripping a plate-type tensile specimen having generally T-shaped end regions in a dynamic tension fatigue testing apparatus comprising an annular housing having an open-ended elongated cavity therein, a plurality of hydraulic piston means supported by the housing in a spaced array about the cavity, and a specimen-supporting plate means overlying the piston means at one end of the elongated cavity and displaceable by said piston means in a longitudinal direction with respect to the longitudinal axis of the cavity, said apparatus for gripping a flat plate-type tensile specimen comprising: a pair of elongated pull rods each having oppositely disposed first and second end regions; a pair of mounting means carried by said plate means with each mounting means for pivotally attaching the first end region of each of said pull rods in a central region of said plate means for supporting said pair of elongated pull rods in a side-by-side relationship along a common longitudinal centerline within said cavity; recess means in the second end region of each of said pull rods in adjacently disposed surface regions thereof with said recess means facing one another and each adapted to receive one side of one of the generally T-shaped end regions of the plate-type tensile specimen; and load-bearing means positionable in each of said recess means and adapted to bear against a shoulder on each side of the generally T-shaped end region of the plate-type tensile specimen when a tensile loading is applied thereon.

Dark Light, Rod Saturation, and the Absolute and Incremental Sensitivity of Mouse Cone Vision

PubMed Central

Naarendorp, Frank; Esdaille, Tricia M.; Banden, Serenity M.; Andrews-Labenski, John; Gross, Owen P.; Pugh, Edward N.

2012-01-01

Visual thresholds of mice for the detection of small, brief targets were measured with a novel behavioral methodology in the dark and in the presence of adapting lights spanning ∼8 log10 units of intensity. To help dissect the contributions of rod and cone pathways, both wild-type mice and mice lacking rod (Gnat1−/−) or cone (Gnat2cpfl3) function were studied. Overall, the visual sensitivity of mice was found to be remarkably similar to that of the human peripheral retina. Rod absolute threshold corresponded to 12-15 isomerized pigment molecules (R*) in image fields of 800 to 3000 rods. Rod “dark light” (intrinsic retinal noise in darkness) corresponded to that estimated previously from single-cell recordings, 0.012R*s−1rod−1, indicating that spontaneous thermalisomerizations are responsible. Psychophysical rod saturation was measured for the first time in a nonhman species and found to be very similar to that of the human rod monochromat. Cone threshold corresponded to ∼5 R* cone−1 in an image field of 280 cones. Cone dark light was equivalent to ∼5000 R*s−1 cone−1, consistent with primate single-cell data but 100-fold higher than predicted by recent measurements of the rate of thermal isomerization of mouse cone opsins, indicating that nonopsin sources of noise determine cone threshold. The new, fully automated behavioral method is based on the ability of mice to learn to interrupt spontaneous wheel running on the presentation of a visual cue and provides an efficient and highly reliable means of examining visual function in naturally behaving normal and mutant mice. PMID:20844144

Mitigation strategies and unforseen consequences: A systematic assessment of the adaption of upper midwest agriculture to future climate change

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doering, O.; Lowenberg-DeBoer, J.; Habeck, M.

1997-12-31

Our starting point is the assumption of global climate change that doubles CO{sub 2} in the Upper Midwest by 2050. This work then concentrates on determining agriculture in the Upper Midwest successfully adapts to such a climate change.

37. MISSISSIPPI, LOWNDES CO. COLUMBUS BRIDGE, CONSTRUCTION End of Main ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

37. MISSISSIPPI, LOWNDES CO. COLUMBUS BRIDGE, CONSTRUCTION End of Main St., Columbus Overhead view of round, swing pier, showing steel reinforcing rods, workmen. During construction, 1925-27. Credit: Shenks Photography, Columbus, Ms, owner. O. Pruitt, photographer, ca. 1926. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

Rod stiffness as a risk factor of proximal junctional kyphosis after adult spinal deformity surgery: comparative study between cobalt chrome multiple-rod constructs and titanium alloy two-rod constructs.

PubMed

Han, Sanghyun; Hyun, Seung-Jae; Kim, Ki-Jeong; Jahng, Tae-Ahn; Lee, Subum; Rhim, Seung-Chul

2017-07-01

Little is known about the effect of rod stiffness as a risk factor of proximal junctional kyphosis (PJK) after adult spinal deformity (ASD) surgery. The aim of this study was to compare radiographic outcomes after the use of cobalt chrome multiple-rod constructs (CoCr MRCs) and titanium alloy two-rod constructs (Ti TRCs) for ASD surgery with a minimum 1-year follow-up. Retrospective case-control study in two institutes. We included 54 patients who underwent ASD surgery with fusion to the sacrum in two academic institutes between 2002 and 2015. Radiographic outcomes were measured on the standing lateral radiographs before surgery, 1 month postoperatively, and at ultimate follow-up. The outcome measures were composed of pre- and postoperative sagittal vertical axis (SVA), pre- and postoperative lumbar lordosis (LL), pre- and postoperative thoracic kyphosis (TK)+LL+pelvic incidence (PI), pre- and postoperative PI minus LL, level of uppermost instrumented vertebra (UIV), evaluation of fusion after surgery, the presence of PJK, and the occurrence of rod fracture. We reviewed the medical records of 54 patients who underwent ASD surgery. Of these, 20 patients had CoCr MRC and 34 patients had Ti TRC. Baseline data and radiographic measurements were compared between the two groups. The Mann-Whitney U test, the chi-square test, and the Fisher exact test were used to compare outcomes between the groups. The patients of the groups were similar in terms of age, gender, diagnosis, number of three-column osteotomy, levels fused, bone mineral density, preoperative TK, pre- and postoperative TK+LL+PI, SVA difference, LL change, pre- and postoperative PI minus LL, and location of UIV (upper or lower thoracic level). However, there were significant differences in the occurrence of PJK and rod breakage (PJK: CoCr MRC: 12 [60%] vs. Ti TRC: 9 [26.5%], p=.015; occurrence of rod breakage: CoCr MRC: 0 [0%] vs. Ti TRC: 11 [32.4%], p=.004). The time of PJK was less than 12 months after surgery in the CoCr MRC group. However, 55.5% (5/9) of PJK developed over 12 months after surgery in the Ti TRC group. Increasing the rod stiffness by the use of cobalt chrome rod and can prevent rod breakage but adversely affects the occurrence and the time of PJK. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of Rhodopsin Phosphorylation on Dark Adaptation in Mouse Rods

PubMed Central

Berry, Justin; Frederiksen, Rikard; Yao, Yun; Nymark, Soile

2016-01-01

Rhodopsin is a prototypical G-protein-coupled receptor (GPCR) that is activated when its 11-cis-retinal moiety is photoisomerized to all-trans retinal. This step initiates a cascade of reactions by which rods signal changes in light intensity. Like other GPCRs, rhodopsin is deactivated through receptor phosphorylation and arrestin binding. Full recovery of receptor sensitivity is then achieved when rhodopsin is regenerated through a series of steps that return the receptor to its ground state. Here, we show that dephosphorylation of the opsin moiety of rhodopsin is an extremely slow but requisite step in the restoration of the visual pigment to its ground state. We make use of a novel observation: isolated mouse retinae kept in standard media for routine physiologic recordings display blunted dephosphorylation of rhodopsin. Isoelectric focusing followed by Western blot analysis of bleached isolated retinae showed little dephosphorylation of rhodopsin for up to 4 h in darkness, even under conditions when rhodopsin was completely regenerated. Microspectrophotometeric determinations of rhodopsin spectra show that regenerated phospho-rhodopsin has the same molecular photosensitivity as unphosphorylated rhodopsin and that flash responses measured by trans-retinal electroretinogram or single-cell suction electrode recording displayed dark-adapted kinetics. Single quantal responses displayed normal dark-adapted kinetics, but rods were only half as sensitive as those containing exclusively unphosphorylated rhodopsin. We propose a model in which light-exposed retinae contain a mixed population of phosphorylated and unphosphorylated rhodopsin. Moreover, complete dark adaptation can only occur when all rhodopsin has been dephosphorylated, a process that requires >3 h in complete darkness. SIGNIFICANCE STATEMENT G-protein-coupled receptors (GPCRs) constitute the largest superfamily of proteins that compose ∼4% of the mammalian genome whose members share a common membrane topology. Signaling by GPCRs regulate a wide variety of physiological processes, including taste, smell, hearing, vision, and cardiovascular, endocrine, and reproductive homeostasis. An important feature of GPCR signaling is its timely termination. This normally occurs when, after their activation, GPCRs are rapidly phosphorylated by specific receptor kinases and subsequently bound by cognate arrestins. Recovery of receptor sensitivity to the ground state then requires dephosphorylation of the receptor and unbinding of arrestin, processes that are poorly understood. Here we investigate in mouse rod photoreceptors the relationship between rhodopsin dephosphorylation and recovery of visual sensitivity. PMID:27358455

DOE Office of Scientific and Technical Information (OSTI.GOV)

Challabotla, Niranjan Reddy; Zhao, Lihao; Andersson, Helge I.

The rotational motion of inertia-free spheroids has been studied in a numerically simulated turbulent channel flow. Although inertia-free spheroids were translated as tracers with the flow, neither the disk-like nor the rod-like particles adapted to the fluid rotation. The flattest disks preferentially aligned their symmetry axes normal to the wall, whereas the longest rods were parallel with the wall. The shape-dependence of the particle orientations carried over to the particle rotation such that the mean spin was reduced with increasing departure from sphericity. The streamwise spin fluctuations were enhanced due to asphericity, but substantially more for prolate than for oblatemore » spheroids.« less

Incidence of proximal junctional kyphosis with magnetic expansion control rods in early onset scoliosis.

PubMed

Inaparthy, P; Queruz, J C; Bhagawati, D; Thakar, C; Subramanian, T; Nnadi, C

2016-10-01

The introduction of magnetic expansion control growth rods for the surgical management of EOS has gained popularity. However, there are no published studies on the incidence of proximal junctional kyphosis (PJK) using this technique. The aim of this study is to report the incidence of PJK following treatment with magnetic growth rods in EOS. Retrospective review of data from 21 cases (12 males, 9 females) over 3 years. PJK was obtained from whole spine X-rays pre-op, immediate post-op and last follow-up. Cobb angle was measured between the superior end plate of vertebra two levels above the upper instrumented vertebra (UIV) and the inferior end plate of the UIV. A difference of >10° between the pre-operative x-rays and the last follow-up X-rays was recorded as PJK. 6/21 (28.6 %) had proximal junctional kyphosis of more than 10° at last follow-up. Average age was 5.3. Average follow-up was 32.5 months. All the patients with PJK were syndromic. Four out of these six patients were males (66 %). Average PJK angle was 25.55°. Average pre-operative kyphosis was 52.5°. Average number of distractions was 7.4. All six patients had syndromic association. 3/6 patients (50 %) were conversion cases treated with traditional growth rods previously (TGR). None of the patients required unplanned surgery for PJK. The incidence of PJK in EOS patients treated with magnetic rods is favourably comparable to that reported with traditional growth rods. Also, children who are male, syndromic, hyperkyphotic, and younger must be monitored closely.

Selectively Lockable Knee Brace

NASA Technical Reports Server (NTRS)

Myers, W. Neill (Inventor); Shadoan, Michael D. (Inventor); Forbes, John C. (Inventor); Baker, Kevin J. (Inventor); Rice, Darron C. (Inventor)

1996-01-01

A knee brace for aiding in rehabilitation of damaged leg muscles includes upper and lower housings normally pivotable one relative to the other about the knee joint axis of a patient. The upper housing is attachable to the thigh of the patient above the knee joint while the lower housing is secured to a stirrup which extends downwardly along the patient's leg and is attached to the patient's shoe. An actuation rod is carried within the lower housing and is coupled to a cable. The upper and lower housings carry cooperative clutch/brake elements which normally are disengaged to permit relative movement between the upper and lower housings. When the cable is extended the clutch/brake elements engage and lock the housings together. A heel strike mechanism fastened to the stirrup and the heel of the shoe is connected to the cable to selectively extend the cable and lock the brace in substantially any position when the patient places weight on the heel.

Selectively lockable knee brace

NASA Technical Reports Server (NTRS)

Myers, Neill (Inventor); Shadoan, Mike (Inventor); Forbes, John (Inventor); Baker, Kevin (Inventor)

1994-01-01

A knee brace for aiding in rehabilitation of damaged leg muscles includes upper and lower housings, normally pivotable, one relative to the other about the knee joint axis of a patient. The upper housing is attachable to the thigh of the patient above the knee joint, while the lower housing is secured to a stirrup which extends downwardly along the patient's leg and is attached to the patient's shoe. An actuation rod is carried within the lower housing and is coupled to a cable. The upper and lower housings carry cooperative clutch/brake elements which normally are disengaged to permit relative movement between the upper and lower housings. When the cable is extended, the clutch/brake elements engage and lock the housings together. A heel strike mechanism fastened to the stirrup and the heel of the shoe is connected to the cable to selectively extend the cable and lock the brace in substantially any position when the patient places weight on the heel.

Analysis of MreB interactors in Chlamydia reveals a RodZ homolog but fails to detect an interaction with MraY.

PubMed

Ouellette, Scot P; Rueden, Kelsey J; Gauliard, Emilie; Persons, Logan; de Boer, Piet A; Ladant, Daniel

2014-01-01

Chlamydia is an obligate intracellular bacterial pathogen that has significantly reduced its genome in adapting to the intracellular environment. One class of genes for which the bacterium has few annotated examples is cell division, and Chlamydia lacks FtsZ, a central coordinator of the division apparatus. We have previously implicated MreB as a potential substitute for FtsZ in Chlamydia (Ouellette et al., 2012). Thus, to identify new chlamydial cell division components, we searched for proteins that interacted with MreB. We performed a small-scale screen using a Gateway® compatible version of the Bacterial Adenylate Cyclase Two Hybrid (BACTH) system, BACTHGW, to detect proteins interacting with chlamydial MreB and identified a RodZ (YfgA) homolog. The chlamydial RodZ aligns well with the cytoplasmic domain of E. coli RodZ but lacks the periplasmic domain that is dispensable for rod cell shape maintenance in E. coli. The expression pattern of yfgA/rodZ was similar to that of mreB and ftsI, suggesting that these genes may operate in a common functional pathway. The chlamydial RodZ correctly localized to the membrane of E. coli but was unable to complement an E. coli rodZ mutant strain, likely because of the inability of chlamydial RodZ to interact with the native E. coli MreB. Finally, we also tested whether chlamydial MreB could interact with MraY, as suggested by Gaballah et al. (2011). However, we did not detect an interaction between these proteins even when using an implementation of the BACTH system to allow native orientation of the N- and C-termini of MraY in the periplasm. Thus, further work will be needed to establish this proposed interaction. In sum, we have added to the repertoire of potential cell division proteins of Chlamydia.

Analysis of MreB interactors in Chlamydia reveals a RodZ homolog but fails to detect an interaction with MraY

PubMed Central

Ouellette, Scot P.; Rueden, Kelsey J.; Gauliard, Emilie; Persons, Logan; de Boer, Piet A.; Ladant, Daniel

2014-01-01

Chlamydia is an obligate intracellular bacterial pathogen that has significantly reduced its genome in adapting to the intracellular environment. One class of genes for which the bacterium has few annotated examples is cell division, and Chlamydia lacks FtsZ, a central coordinator of the division apparatus. We have previously implicated MreB as a potential substitute for FtsZ in Chlamydia (Ouellette et al., 2012). Thus, to identify new chlamydial cell division components, we searched for proteins that interacted with MreB. We performed a small-scale screen using a Gateway® compatible version of the Bacterial Adenylate Cyclase Two Hybrid (BACTH) system, BACTHGW, to detect proteins interacting with chlamydial MreB and identified a RodZ (YfgA) homolog. The chlamydial RodZ aligns well with the cytoplasmic domain of E. coli RodZ but lacks the periplasmic domain that is dispensable for rod cell shape maintenance in E. coli. The expression pattern of yfgA/rodZ was similar to that of mreB and ftsI, suggesting that these genes may operate in a common functional pathway. The chlamydial RodZ correctly localized to the membrane of E. coli but was unable to complement an E. coli rodZ mutant strain, likely because of the inability of chlamydial RodZ to interact with the native E. coli MreB. Finally, we also tested whether chlamydial MreB could interact with MraY, as suggested by Gaballah et al. (2011). However, we did not detect an interaction between these proteins even when using an implementation of the BACTH system to allow native orientation of the N- and C-termini of MraY in the periplasm. Thus, further work will be needed to establish this proposed interaction. In sum, we have added to the repertoire of potential cell division proteins of Chlamydia. PMID:24936201

Genetic algorithm based active vibration control for a moving flexible smart beam driven by a pneumatic rod cylinder

NASA Astrophysics Data System (ADS)

Qiu, Zhi-cheng; Shi, Ming-li; Wang, Bin; Xie, Zhuo-wei

2012-05-01

A rod cylinder based pneumatic driving scheme is proposed to suppress the vibration of a flexible smart beam. Pulse code modulation (PCM) method is employed to control the motion of the cylinder's piston rod for simultaneous positioning and vibration suppression. Firstly, the system dynamics model is derived using Hamilton principle. Its standard state-space representation is obtained for characteristic analysis, controller design, and simulation. Secondly, a genetic algorithm (GA) is applied to optimize and tune the control gain parameters adaptively based on the specific performance index. Numerical simulations are performed on the pneumatic driving elastic beam system, using the established model and controller with tuned gains by GA optimization process. Finally, an experimental setup for the flexible beam driven by a pneumatic rod cylinder is constructed. Experiments for suppressing vibrations of the flexible beam are conducted. Theoretical analysis, numerical simulation and experimental results demonstrate that the proposed pneumatic drive scheme and the adopted control algorithms are feasible. The large amplitude vibration of the first bending mode can be suppressed effectively.

Renal osteodystrophy, phosphate homeostasis, and vascular calcification.

PubMed

Hruska, Keith A; Saab, Georges; Mathew, Suresh; Lund, Richard

2007-01-01

New advances in the pathogenesis of renal osteodystrophy (ROD) change the perspective from which many of its features and treatment are viewed. Calcium, phosphate, parathyroid hormone (PTH), and vitamin D have been shown to be important determinants of survival associated with kidney diseases. Now ROD dependent and independent of these factors is linked to survival more than just skeletal frailty. This review focuses on recent discoveries that renal injury impairs skeletal anabolism decreasing the osteoblast compartment of the skeleton and consequent bone formation. This discovery and the discovery that PTH regulates the hematopoietic stem cell niche alters our view of secondary hyperparathyroidism in chronic kidney disease (CKD) from that of a disease to that of a necessary adaptation to renal injury that goes awry. Furthermore, ROD is shown to be an underappreciated factor in the level of the serum phosphorus in CKD. The discovery and the elucidation of the mechanism of hyperphosphatemia as a cardiovascular risk in CKD change the view of ROD. It is now recognized as more than a skeletal disorder, it is an important component of the mortality of CKD that can be treated.

ELECTROMAGNETIC APPARATUS FOR MOVING A ROD

DOEpatents

Young, J.N.

1957-08-20

An electromagnetic device for moving an object in a linear path by increments is described. The device is specifically adapted for moving a neutron absorbing control rod into and out of the core of a reactor and consists essentially of an extension member made of magnetic material connected to one end of the control rod and mechanically flexible to grip the walls of a sleeve member when flexed, a magnetic sleeve member coaxial with and slidable between limit stops along the flexible extension, electromagnetic coils substantially centrally located with respect to the flexible extension to flex the extension member into gripping engagement with the sleeve member when ener gized, moving electromagnets at each end of the sleeve to attract the sleeve when energized, and a second gripping electromagnet positioned along the flexible extension at a distance from the previously mentioned electromagnets for gripping the extension member when energized. In use, the second gripping electromagnet is deenergized, the first gripping electromagnet is energized to fix the extension member in the sleeve, and one of the moving electromagnets is energized to attract the sleeve member toward it, thereby moving the control rod.

Visual pigments of marine carnivores: pinnipeds, polar bear, and sea otter.

PubMed

Levenson, David H; Ponganis, Paul J; Crognale, Michael A; Deegan, Jess F; Dizon, Andy; Jacobs, Gerald H

2006-08-01

Rod and cone visual pigments of 11 marine carnivores were evaluated. Rod, middle/long-wavelength sensitive (M/L) cone, and short-wavelength sensitive (S) cone opsin (if present) sequences were obtained from retinal mRNA. Spectral sensitivity was inferred through evaluation of known spectral tuning residues. The rod pigments of all but one of the pinnipeds were similar to those of the sea otter, polar bear, and most other terrestrial carnivores with spectral peak sensitivities (lambda(max)) of 499 or 501 nm. Similarly, the M/L cone pigments of the pinnipeds, polar bear, and otter had inferred lambda(max) of 545 to 560 nm. Only the rod opsin sequence of the elephant seal had sensitivity characteristic of adaptation for vision in the marine environment, with an inferred lambda(max) of 487 nm. No evidence of S cones was found for any of the pinnipeds. The polar bear and otter had S cones with inferred lambda(max) of approximately 440 nm. Flicker-photometric ERG was additionally used to examine the in situ sensitivities of three species of pinniped. Despite the use of conditions previously shown to evoke cone responses in other mammals, no cone responses could be elicited from any of these pinnipeds. Rod photoreceptor responses for all three species were as predicted by the genetic data.

Multiple rod-cone and cone-rod photoreceptor transmutations in snakes: evidence from visual opsin gene expression.

PubMed

Simões, Bruno F; Sampaio, Filipa L; Loew, Ellis R; Sanders, Kate L; Fisher, Robert N; Hart, Nathan S; Hunt, David M; Partridge, Julian C; Gower, David J

2016-01-27

In 1934, Gordon Walls forwarded his radical theory of retinal photoreceptor 'transmutation'. This proposed that rods and cones used for scotopic and photopic vision, respectively, were not fixed but could evolve into each other via a series of morphologically distinguishable intermediates. Walls' prime evidence came from series of diurnal and nocturnal geckos and snakes that appeared to have pure-cone or pure-rod retinas (in forms that Walls believed evolved from ancestors with the reverse complement) or which possessed intermediate photoreceptor cells. Walls was limited in testing his theory because the precise identity of visual pigments present in photoreceptors was then unknown. Subsequent molecular research has hitherto neglected this topic but presents new opportunities. We identify three visual opsin genes, rh1, sws1 and lws, in retinal mRNA of an ecologically and taxonomically diverse sample of snakes central to Walls' theory. We conclude that photoreceptors with superficially rod- or cone-like morphology are not limited to containing scotopic or photopic opsins, respectively. Walls' theory is essentially correct, and more research is needed to identify the patterns, processes and functional implications of transmutation. Future research will help to clarify the fundamental properties and physiology of photoreceptors adapted to function in different light levels. © 2016 The Author(s).

Drop Ejection From an Oscillating Rod

NASA Technical Reports Server (NTRS)

Wilkes, E. D.; Basaran, O. A.

1999-01-01

The dynamics of a drop of a Newtonian liquid that is pendant from or sessile on a solid rod that is forced to undergo time-periodic oscillations along its axis is studied theoretically. The free boundary problem governing the time evolution of the shape of the drop and the flow field inside it is solved by a method of lines using a finite element algorithm incorporating an adaptive mesh. When the forcing amplitude is small, the drop approaches a limit cycle at large times and undergoes steady oscillations thereafter. However, drop breakup is the consequence if the forcing amplitude exceeds a critical value. Over a wide range of amplitudes above this critical value, drop ejection from the rod occurs during the second oscillation period from the commencement of rod motion. Remarkably, the shape of the interface at breakup and the volume of the primary drop formed are insensitive to changes in forcing amplitude. The interface shape at times close to and at breakup is a multi-valued function of distance measured along the rod axis and hence cannot be described by recently popularized one-dimensional approximations. The computations show that drop ejection occurs without the formation of a long neck. Therefore, this method of drop formation holds promise of preventing formation of undesirable satellite droplets.

Visual function in patients with cone-rod dystrophy (CRD) associated with mutations in the ABCA4(ABCR) gene.

PubMed

Birch, D G; Peters, A Y; Locke, K L; Spencer, R; Megarity, C F; Travis, G H

2001-12-01

Mutations in the ABCA4(ABCR) gene cause autosomal recessive Stargardt disease (STGD). ABCR mutations were identified in patients with cone-rod dystrophy (CRD) and retinitis pigmentosa (RP) by direct sequencing of all 50 exons in 40 patients. Of 10 patients with RP, one contained two ABCR mutations suggesting a compound heterozygote. This patient had a characteristic fundus appearance with attenuated vessels, pale disks and bone-spicule pigmentation. Rod electroretinograms (ERGs) were non-detectable, cone ERGs were greatly reduced in amplitude and delayed in implicit time, and visual fields were constricted to 10 degrees diameter. Eleven of 30 (37%) patients with CRD had mutations in ABCR. In general, these patients showed reduced but detectable rod ERG responses, reduced and delayed cone responses, and poor visual acuity. Rod photoresponses to high intensity flashes were of reduced maximum amplitude but showed normal values for the gain of phototransduction. Most CRD patients with mutations in ABCR showed delayed recovery of sensitivity (dark adaptation) following exposure to bright light. Pupils were also significantly smaller in these patients compared to controls at 30 min following light exposure, consistent with a persistent 'equivalent light' background due to the accumulation of a tentatively identified 'noisy' photoproduct. Copyright 2001 Academic Press.

Might the Rorschach be a projective test after all? Social projection of an undesired trait alters Rorschach Oral Dependency scores.

PubMed

Bornstein, Robert F

2007-06-01

The degree to which projection plays a role in Rorschach (Rorschach, 1921/1942) responding remains controversial, in part because extant data have yielded inconclusive results. In this investigation, I examined the impact of social projection on Rorschach Oral Dependency (ROD) scores using methods adapted from social cognition research. In Study 1, I prescreened 85 college students (40 women and 45 men) with the ROD scale and a widely used self-report measure of dependency, the Interpersonal Dependency Inventory (IDI; Hirschfeld et al., 1977). Results show that informing participants who scored low on the IDI that they were in fact highly dependent led to significant increases in ROD scores; I did not obtain parallel ROD increases for participants who scored high on the IDI or for participants who received low-dependent feedback. In Study 2, I examined a separate sample of 80 prescreened college students (40 women and 40 men) and showed that providing low self-report participants an opportunity to attribute dependency to a fictional target person prior to Rorschach responding attenuated the impact of high-dependent feedback on ROD scores. These results suggest that projection played a role in at least one domain of Rorschach responding. I discuss theoretical, clinical, and empirical implications of these results.

Efficient Nose-to-Lung (N2L) Aerosol Delivery with a Dry Powder Inhaler

PubMed Central

Golshahi, Laleh; Behara, Srinivas R.B.; Tian, Geng; Farkas, Dale R.; Hindle, Michael

2015-01-01

Abstract Purpose: Delivering aerosols to the lungs through the nasal route has a number of advantages, but its use has been limited by high depositional loss in the extrathoracic airways. The objective of this study was to evaluate the nose-to-lung (N2L) delivery of excipient enhanced growth (EEG) formulation aerosols generated with a new inline dry powder inhaler (DPI). The device was also adapted to enable aerosol delivery to a patient simultaneously receiving respiratory support from high flow nasal cannula (HFNC) therapy. Methods: The inhaler delivered the antibiotic ciprofloxacin, which was formulated as submicrometer combination particles containing a hygroscopic excipient prepared by spray-drying. Nose-to-lung delivery was assessed using in vitro and computational fluid dynamics (CFD) methods in an airway model that continued through the upper tracheobronchial region. Results: The best performing device contained a 2.3 mm flow control orifice and a 3D rod array with a 3-4-3 rod pattern. Based on in vitro experiments, the emitted dose from the streamlined nasal cannula had a fine particle fraction <5 μm of 95.9% and mass median aerodynamic diameter of 1.4 μm, which was considered ideal for nose-to-lung EEG delivery. With the 2.3-343 device, condensational growth in the airways increased the aerosol size to 2.5–2.7 μm and extrathoracic deposition was <10%. CFD results closely matched the in vitro experiments and predicted that nasal deposition was <2%. Conclusions: The developed DPI produced high efficiency aerosolization with significant size increase of the aerosol within the airways that can be used to enable nose-to-lung delivery and aerosol administration during HFNC therapy. PMID:25192072

Rod- versus cone-driven ERGs at different stimulus sizes in normal subjects and retinitis pigmentosa patients.

PubMed

Aher, Avinash J; McKeefry, Declan J; Parry, Neil R A; Maguire, John; Murray, I J; Tsai, Tina I; Huchzermeyer, Cord; Kremers, Jan

2018-02-01

To study how rod- and cone-driven responses depend on stimulus size in normal subjects and patients with retinitis pigmentosa (RP), and to show that comparisons between responses to full-field (FF) and smaller stimuli can be useful in diagnosing and monitoring disorders of the peripheral retina without the need for lengthy dark adaptation periods. The triple silent substitution technique was used to isolate L-cone-, M-cone- and rod-driven ERGs with 19, 18 and 33% photoreceptor contrasts, respectively, under identical mean luminance conditions. Experiments were conducted on five normal subjects and three RP patients. ERGs on control subjects were recorded at nine different temporal frequencies (between 2 and 60 Hz) for five different stimulus sizes: FF, 70°, 60°, 50° and 40° diameter circular stimuli. Experiments on RP patients involved rod- and L-cone-driven ERG measurements with FF and 40° stimuli at 8 and 48 Hz. Response amplitudes were defined as those of the first harmonic component after Fourier analysis. In normal subjects, rod-driven responses displayed a fundamentally different behavior than cone-driven responses, particularly at low temporal frequencies. At low and intermediate temporal frequencies (≤ 12 Hz), rod-driven signals increased by a factor of about four when measured with smaller stimuli. In contrast, L- and M-cone-driven responses in this frequency region did not change substantially with stimulus size. At high temporal frequencies (≥ 24 Hz), both rod- and cone-driven response amplitudes decreased with decreasing stimulus size. Signals obtained from rod-isolating stimuli under these conditions are likely artefactual. Interestingly, in RP patients, both rod-driven and L-cone-driven ERGs were similar using 40° and FF stimuli. The increased responses with smaller stimuli in normal subjects to rod-isolating stimuli indicate that a fundamentally different mechanism drives the ERGs in comparison with the cone-driven responses. We propose that the increased responses are caused by stray light stimulating the peripheral retina, thereby allowing peripheral rod-driven function to be studied using the triple silent substitution technique at photopic luminances. The method is effective in studying impaired peripheral rod- and cone- function in RP patients.

Content Range and Precision of a Computer Adaptive Test of Upper Extremity Function for Children with Cerebral Palsy

ERIC Educational Resources Information Center

Montpetit, Kathleen; Haley, Stephen; Bilodeau, Nathalie; Ni, Pengsheng; Tian, Feng; Gorton, George, III; Mulcahey, M. J.

2011-01-01

This article reports on the content range and measurement precision of an upper extremity (UE) computer adaptive testing (CAT) platform of physical function in children with cerebral palsy. Upper extremity items representing skills of all abilities were administered to 305 parents. These responses were compared with two traditional standardized…

Experimental investigation on circumferential and axial temperature gradient over fuel channel under LOCA

NASA Astrophysics Data System (ADS)

Yadav, Ashwini Kumar; kumar, Ravi; Gupta, Akhilesh; Chatterjee, Barun; Mukhopadhyay, Deb; Lele, H. G.

2014-06-01

In a nuclear reactor temperature rises drastically in fuel channels under loss of coolant accident due to failure of primary heat transportation system. Present investigation has been carried out to capture circumferential and axial temperature gradients during fully and partially voiding conditions in a fuel channel using 19 pin fuel element simulator. A series of experiments were carried out by supplying power to outer, middle and center rods of 19 pin fuel simulator in ratio of 1.4:1.1:1. The temperature at upper periphery of pressure tube (PT) was slightly higher than at bottom due to increase in local equivalent thermal conductivity from top to bottom of PT. To simulate fully voided conditions PT was pressurized at 2.0 MPa pressure with 17.5 kW power injection. Ballooning initiated from center and then propagates towards the ends and hence axial temperature difference has been observed along the length of PT. For asymmetric heating, upper eight rods of fuel simulator were activated and temperature difference up-to 250 °C has been observed from top to bottom periphery of PT. Such situation creates steep circumferential temperature gradient over PT and could lead to breaching of PT under high pressure.

The mechanical response of talin

NASA Astrophysics Data System (ADS)

Yao, Mingxi; Goult, Benjamin T.; Klapholz, Benjamin; Hu, Xian; Toseland, Christopher P.; Guo, Yingjian; Cong, Peiwen; Sheetz, Michael P.; Yan, Jie

2016-07-01

Talin, a force-bearing cytoplasmic adapter essential for integrin-mediated cell adhesion, links the actin cytoskeleton to integrin-based cell-extracellular matrix adhesions at the plasma membrane. Its C-terminal rod domain, which contains 13 helical bundles, plays important roles in mechanosensing during cell adhesion and spreading. However, how the structural stability and transition kinetics of the 13 helical bundles of talin are utilized in the diverse talin-dependent mechanosensing processes remains poorly understood. Here we report the force-dependent unfolding and refolding kinetics of all talin rod domains. Using experimentally determined kinetics parameters, we determined the dynamics of force fluctuation during stretching of talin under physiologically relevant pulling speeds and experimentally measured extension fluctuation trajectories. Our results reveal that force-dependent stochastic unfolding and refolding of talin rod domains make talin a very effective force buffer that sets a physiological force range of only a few pNs in the talin-mediated force transmission pathway.

Mesopic and Photopic Rod and Cone Photoreceptor-Driven Visual Processes in Mice With Long-Wavelength-Shifted Cone Pigments.

PubMed

Tsai, Tina I; Joachimsthaler, Anneka; Kremers, Jan

2017-10-01

The clearer divergence in spectral sensitivity between native rod and human L-cone (L*-cone) opsins in the transgenic Opn1lwLIAIS mouse (LIAIS) allows normal visual processes mediated by these photoreceptor subtypes to be isolated effectively using the silent substitution technique. The objective of this study was to further characterize the influence of mean luminance and temporal frequency on the functional properties of signals originating in each photoreceptor separately and independently of adaptation state in LIAIS mice. Electroretinographic (ERG) recordings to sine-wave rod and L*-cone modulation at different mean luminances (0.1-130.0 cd/m2) and temporal frequencies (6-26 Hz) were examined in anesthetized LIAIS (N = 17) and C57Bl/6 mice (N = 8). We report maximum rod-driven response with 8-Hz modulation at 0.1 to 0.5 cd/m2, which was almost four times larger than maximum cone-driven response at 8 Hz, 21.5 to 130 cd/m2. Over these optimal luminances, both rod- and cone-driven response amplitudes exhibited low-pass functions with similar frequency resolution limits, albeit their distinct luminance sensitivities. There were, however, two distinguishing features: (1) the frequency-dependent amplitude decrease of rod-driven responses was more profound, and (2) linear relationships describing rod-driven response phases as a function of stimulus frequency were steeper. Employing the silent substitution method with stimuli of appropriate luminance on the LIAIS mouse (as on human observers) increases the specificity, robustness, and scope to which photoreceptor-driven responses can be reliably assayed compared to the standard photoreceptor isolation methods.

Surviving bacterial sibling rivalry: inducible and reversible phenotypic switching in Paenibacillus dendritiformis.

PubMed

Be'er, Avraham; Florin, E-L; Fisher, Carolyn R; Swinney, Harry L; Payne, Shelley M

2011-01-01

Natural habitats vary in available nutrients and room for bacteria to grow, but successful colonization can lead to overcrowding and stress. Here we show that competing sibling colonies of Paenibacillus dendritiformis bacteria survive overcrowding by switching between two distinct vegetative phenotypes, motile rods and immotile cocci. Growing colonies of the rod-shaped bacteria produce a toxic protein, Slf, which kills cells of encroaching sibling colonies. However, sublethal concentrations of Slf induce some of the rods to switch to Slf-resistant cocci, which have distinct metabolic and resistance profiles, including resistance to cell wall antibiotics. Unlike dormant spores of P. dendritiformis, the cocci replicate. If cocci encounter conditions that favor rods, they secrete a signaling molecule that induces a switch to rods. Thus, in contrast to persister cells, P. dendritiformis bacteria adapt to changing environmental conditions by inducible and reversible phenotypic switching. In favorable environments, species may face space and nutrient limits due to overcrowding. Bacteria provide an excellent model for analyzing principles underlying overcrowding and regulation of density in nature, since their population dynamics can be easily and accurately assessed under controlled conditions. We describe a newly discovered mechanism for survival of a bacterial population during overcrowding. When competing with sibling colonies, Paenibacillus dendritiformis produces a lethal protein (Slf) that kills cells at the interface of encroaching colonies. Slf also induces a small proportion of the cells to switch from motile, rod-shaped cells to nonmotile, Slf-resistant, vegetative cocci. When crowding is reduced and nutrients are no longer limiting, the bacteria produce a signal that induces cocci to switch back to motile rods, allowing the population to spread. Genes encoding components of this phenotypic switching pathway are widespread among bacterial species, suggesting that this survival mechanism is not unique to P. dendritiformis.

Phenotypic diversity in autosomal-dominant cone-rod dystrophy elucidated by adaptive optics retinal imaging

PubMed Central

Song, Hongxin; Rossi, Ethan A; Stone, Edwin; Latchney, Lisa; Williams, David; Dubra, Alfredo; Chung, Mina

2018-01-01

Purpose Several genes causing autosomal-dominant cone-rod dystrophy (AD-CRD) have been identified. However, the mechanisms by which genetic mutations lead to cellular loss in human disease remain poorly understood. Here we combine genotyping with high-resolution adaptive optics retinal imaging to elucidate the retinal phenotype at a cellular level in patients with AD-CRD harbouring a defect in the GUCA1A gene. Methods Nine affected members of a four-generation AD-CRD pedigree and three unaffected first-degree relatives underwent clinical examinations including visual acuity, fundus examination, Goldmann perimetry, spectral domain optical coherence tomography and electroretinography. Genome-wide scan followed by bidirectional sequencing was performed on all affected participants. High-resolution imaging using a custom adaptive optics scanning light ophthalmoscope (AOSLO) was performed for selected participants. Results Clinical evaluations showed a range of disease severity from normal fundus appearance in teenaged patients to pronounced macular atrophy in older patients. Molecular genetic testing showed a mutation in in GUCA1A segregating with disease. AOSLO imaging revealed that of the two teenage patients with mild disease, one had severe disruption of the photoreceptor mosaic while the other had a normal cone mosaic. Conclusions AOSLO imaging demonstrated variability in the pattern of cone and rod cell loss between two teenage cousins with early AD-CRD, who had similar clinical features and had the identical disease-causing mutation in GUCA1A. This finding suggests that a mutation in GUCA1A does not lead to the same degree of AD-CRD in all patients. Modifying factors may mitigate or augment disease severity, leading to different retinal cellular phenotypes. PMID:29074494

Phenotypic diversity in autosomal-dominant cone-rod dystrophy elucidated by adaptive optics retinal imaging.

PubMed

Song, Hongxin; Rossi, Ethan A; Stone, Edwin; Latchney, Lisa; Williams, David; Dubra, Alfredo; Chung, Mina

2018-01-01

Several genes causing autosomal-dominant cone-rod dystrophy (AD-CRD) have been identified. However, the mechanisms by which genetic mutations lead to cellular loss in human disease remain poorly understood. Here we combine genotyping with high-resolution adaptive optics retinal imaging to elucidate the retinal phenotype at a cellular level in patients with AD-CRD harbouring a defect in the GUCA1A gene. Nine affected members of a four-generation AD-CRD pedigree and three unaffected first-degree relatives underwent clinical examinations including visual acuity, fundus examination, Goldmann perimetry, spectral domain optical coherence tomography and electroretinography. Genome-wide scan followed by bidirectional sequencing was performed on all affected participants. High-resolution imaging using a custom adaptive optics scanning light ophthalmoscope (AOSLO) was performed for selected participants. Clinical evaluations showed a range of disease severity from normal fundus appearance in teenaged patients to pronounced macular atrophy in older patients. Molecular genetic testing showed a mutation in in GUCA1A segregating with disease. AOSLO imaging revealed that of the two teenage patients with mild disease, one had severe disruption of the photoreceptor mosaic while the other had a normal cone mosaic. AOSLO imaging demonstrated variability in the pattern of cone and rod cell loss between two teenage cousins with early AD-CRD, who had similar clinical features and had the identical disease-causing mutation in GUCA1A . This finding suggests that a mutation in GUCA1A does not lead to the same degree of AD-CRD in all patients. Modifying factors may mitigate or augment disease severity, leading to different retinal cellular phenotypes. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Novel innate and adaptive lymphocytes: The new players in the pathogenesis of inflammatory upper airway diseases.

PubMed

Liu, Y; Yao, Y; Wang, Z-C; Ning, Q; Liu, Z

2018-06-01

Host immunity (innate and adaptive immunity) plays essential roles in the pathogenesis of inflammatory upper airway diseases, including allergic rhinitis and chronic rhinosinusitis. Recently, the discovery of novel innate immune cells, particularly innate lymphoid cells, has renewed our view on the role of innate immunity in inflammatory upper airway diseases. Meanwhile, the identification of new subsets of T helper (Th) cells, including Th22, Th9 and follicular Th cells, and regulatory B cells in the adaptive immunity, has broadened our knowledge on the complex immune networks in inflammatory upper airway diseases. In this review, we focus on these newly identified innate and adaptive lymphocytes with their contributions to the immunological disturbance in allergic rhinitis and chronic rhinosinusitis. We further discuss the perspective for future research and potential clinical utility of regulating these novel lymphocytes for the treatment of allergic rhinitis and chronic rhinosinusitis. © 2018 John Wiley & Sons Ltd.

Adaptive optics scanning laser ophthalmoscopy in fundus imaging, a review and update.

PubMed

Zhang, Bing; Li, Ni; Kang, Jie; He, Yi; Chen, Xiao-Ming

2017-01-01

Adaptive optics scanning laser ophthalmoscopy (AO-SLO) has been a promising technique in funds imaging with growing popularity. This review firstly gives a brief history of adaptive optics (AO) and AO-SLO. Then it compares AO-SLO with conventional imaging methods (fundus fluorescein angiography, fundus autofluorescence, indocyanine green angiography and optical coherence tomography) and other AO techniques (adaptive optics flood-illumination ophthalmoscopy and adaptive optics optical coherence tomography). Furthermore, an update of current research situation in AO-SLO is made based on different fundus structures as photoreceptors (cones and rods), fundus vessels, retinal pigment epithelium layer, retinal nerve fiber layer, ganglion cell layer and lamina cribrosa. Finally, this review indicates possible research directions of AO-SLO in future.

Adaptive optics scanning laser ophthalmoscopy in fundus imaging, a review and update

PubMed Central

Zhang, Bing; Li, Ni; Kang, Jie; He, Yi; Chen, Xiao-Ming

2017-01-01

Adaptive optics scanning laser ophthalmoscopy (AO-SLO) has been a promising technique in funds imaging with growing popularity. This review firstly gives a brief history of adaptive optics (AO) and AO-SLO. Then it compares AO-SLO with conventional imaging methods (fundus fluorescein angiography, fundus autofluorescence, indocyanine green angiography and optical coherence tomography) and other AO techniques (adaptive optics flood-illumination ophthalmoscopy and adaptive optics optical coherence tomography). Furthermore, an update of current research situation in AO-SLO is made based on different fundus structures as photoreceptors (cones and rods), fundus vessels, retinal pigment epithelium layer, retinal nerve fiber layer, ganglion cell layer and lamina cribrosa. Finally, this review indicates possible research directions of AO-SLO in future. PMID:29181321

Studying Hooke's Law by Using a Pogo Stick

ERIC Educational Resources Information Center

Silva, Nicolas

2011-01-01

Perhaps the pogo stick was little Robert Hooke's favorite childhood toy, consisting of a stiff spring inserted in a tube fixed at the upper end and connected to a moveable rod at the other. Hand grips and a foot rest are connected to the tube. The idea is to jump on it taking advantage of the force provided by the spring when it is compressed.…

Higher order parametric excitation modes for spaceborne quadrupole mass spectrometers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gershman, D. J.; Block, B. P.; Rubin, M.

This paper describes a technique to significantly improve upon the mass peak shape and mass resolution of spaceborne quadrupole mass spectrometers (QMSs) through higher order auxiliary excitation of the quadrupole field. Using a novel multiresonant tank circuit, additional frequency components can be used to drive modulating voltages on the quadrupole rods in a practical manner, suitable for both improved commercial applications and spaceflight instruments. Auxiliary excitation at frequencies near twice that of the fundamental quadrupole RF frequency provides the advantages of previously studied parametric excitation techniques, but with the added benefit of increased sensed excitation amplitude dynamic range and themore » ability to operate voltage scan lines through the center of upper stability islands. Using a field programmable gate array, the amplitudes and frequencies of all QMS signals are digitally generated and managed, providing a robust and stable voltage control system. These techniques are experimentally verified through an interface with a commercial Pfeiffer QMG422 quadrupole rod system. When operating through the center of a stability island formed from higher order auxiliary excitation, approximately 50% and 400% improvements in 1% mass resolution and peak stability were measured, respectively, when compared with traditional QMS operation. Although tested with a circular rod system, the presented techniques have the potential to improve the performance of both circular and hyperbolic rod geometry QMS sensors.« less

LOW CONDUCTANCE HCN1 ION CHANNELS AUGMENT THE FREQUENCY RESPONSE OF ROD AND CONE PHOTORECEPTORS

PubMed Central

Barrow, Andrew J.; Wu, Samuel M.

2009-01-01

Hyperpolarization-activated cyclic nucleotide gated (HCN) ion channels are expressed in several tissues throughout the body, including the heart, the CNS, and the retina. HCN channels are found in many neurons in the retina, but their most established role is in generating the hyperpolarization-activated current, Ih, in photoreceptors. This current makes the light response of rod and cone photoreceptors more transient, an effect similar to that of a high-pass filter. A unique property of HCN channels is their small single channel current, which is below the thermal noise threshold of measuring electronics. We use nonstationary fluctuation analysis (NSFA) in the intact retina to estimate the conductance of single HCN channels, revealing a conductance of approximately 650 fS in both rod and cone photoreceptors. We also analyze the properties of HCN channels in salamander rods and cones, from the biophysical to the functional level, showing that HCN1 is the predominant isoform in both cells, and demonstrate how HCN1 channels speed up the light response of both rods and cones under distinct adaptational conditions. We show that in rods and cones, HCN channels increase the natural frequency response of single cells by modifying the photocurrent input, which is limited in its frequency response by the speed of a molecular signaling cascade. In doing so, HCN channels form the first of several systems in the retina that augment the speed of the visual response, allowing an animal to perceive visual stimuli that change more quickly than the underlying photocurrent. PMID:19420251

Thin-Film Nanowire Networks for Transparent Conductor Applications: Simulations of Sheet Resistance and Percolation Thresholds

NASA Astrophysics Data System (ADS)

Winey, Karen I.; Mutiso, Rose M.; Sherrott, Michelle C.; Rathmell, Aaron R.; Wiley, Benjamin J.

2013-03-01

Thin-film metal nanowire networks are being pursued as a viable alternative to the expensive and brittle indium tin oxide (ITO) for transparent conductors. For high performance applications, nanowire networks must exhibit high transmittance at low sheet resistance. Previously, we have used complimentary experimental, simulation and theoretical techniques to explore the effects of filler aspect ratio (L/D), orientation, and size-dispersity on the electrical conductivity of three-dimensional rod-networks in bulk polymer nanocomposites. We adapted our 3D simulation approach and analytical percolation model to study the electrical properties of thin-film rod-networks. By fitting our simulation results to experimental results, we determined the average effective contact resistance between silver nanowires. This contact resistance was then used to quantify how the sheet resistance depends on the aspect ratio of the rods and to show that networks made of nanowires with L/D greater than 100 yield sheet resistances lower than the required 100 Ohm/sq. We also report the critical area fraction of rods required to form a percolated network in thin-film networks and provide an analytical expression for the critical area fraction as a function of L/D.

High-resolution brain SPECT imaging by combination of parallel and tilted detector heads.

PubMed

Suzuki, Atsuro; Takeuchi, Wataru; Ishitsu, Takafumi; Morimoto, Yuichi; Kobashi, Keiji; Ueno, Yuichiro

2015-10-01

To improve the spatial resolution of brain single-photon emission computed tomography (SPECT), we propose a new brain SPECT system in which the detector heads are tilted towards the rotation axis so that they are closer to the brain. In addition, parallel detector heads are used to obtain the complete projection data set. We evaluated this parallel and tilted detector head system (PT-SPECT) in simulations. In the simulation study, the tilt angle of the detector heads relative to the axis was 45°. The distance from the collimator surface of the parallel detector heads to the axis was 130 mm. The distance from the collimator surface of the tilted detector heads to the origin on the axis was 110 mm. A CdTe semiconductor panel with a 1.4 mm detector pitch and a parallel-hole collimator were employed in both types of detector head. A line source phantom, cold-rod brain-shaped phantom, and cerebral blood flow phantom were evaluated. The projection data were generated by forward-projection of the phantom images using physics models, and Poisson noise at clinical levels was applied to the projection data. The ordered-subsets expectation maximization algorithm with physics models was used. We also evaluated conventional SPECT using four parallel detector heads for the sake of comparison. The evaluation of the line source phantom showed that the transaxial FWHM in the central slice for conventional SPECT ranged from 6.1 to 8.5 mm, while that for PT-SPECT ranged from 5.3 to 6.9 mm. The cold-rod brain-shaped phantom image showed that conventional SPECT could visualize up to 8-mm-diameter rods. By contrast, PT-SPECT could visualize up to 6-mm-diameter rods in upper slices of a cerebrum. The cerebral blood flow phantom image showed that the PT-SPECT system provided higher resolution at the thalamus and caudate nucleus as well as at the longitudinal fissure of the cerebrum compared with conventional SPECT. PT-SPECT provides improved image resolution at not only upper but also at central slices of the cerebrum.

Dark adaptation and the retinoid cycle of vision.

PubMed

Lamb, T D; Pugh, E N

2004-05-01

Following exposure of our eye to very intense illumination, we experience a greatly elevated visual threshold, that takes tens of minutes to return completely to normal. The slowness of this phenomenon of "dark adaptation" has been studied for many decades, yet is still not fully understood. Here we review the biochemical and physical processes involved in eliminating the products of light absorption from the photoreceptor outer segment, in recycling the released retinoid to its original isomeric form as 11-cis retinal, and in regenerating the visual pigment rhodopsin. Then we analyse the time-course of three aspects of human dark adaptation: the recovery of psychophysical threshold, the recovery of rod photoreceptor circulating current, and the regeneration of rhodopsin. We begin with normal human subjects, and then analyse the recovery in several retinal disorders, including Oguchi disease, vitamin A deficiency, fundus albipunctatus, Bothnia dystrophy and Stargardt disease. We review a large body of evidence showing that the time-course of human dark adaptation and pigment regeneration is determined by the local concentration of 11-cis retinal, and that after a large bleach the recovery is limited by the rate at which 11-cis retinal is delivered to opsin in the bleached rod outer segments. We present a mathematical model that successfully describes a wide range of results in human and other mammals. The theoretical analysis provides a simple means of estimating the relative concentration of free 11-cis retinal in the retina/RPE, in disorders exhibiting slowed dark adaptation, from analysis of psychophysical measurements of threshold recovery or from analysis of pigment regeneration kinetics.

Gasket with pushrod retainer

DOEpatents

Knudsen, Julian R.; Welch, Christopher B.

2005-04-26

In an engine having a rocker member adapted to rock about an axis intermediate the rocker member and a pushrod extending from a lower body to an upper body and engaging an end of the rocker member, a gasket for sealing the lower body to the upper body is provided. The gasket includes a sealing portion adapted to substantially seal at least a portion of the upper body to the lower body, and a pushrod support portion extending outwardly from the sealing portion adapted to engage the pushrod. At least a portion of the pushrod support portion engaging the pushrod is constructed from a material that is softer than the material of the pushrod.

Pre-metatarsal skeletal development in tissue culture at unit- and microgravity

NASA Technical Reports Server (NTRS)

Klement, B. J.; Spooner, B. S.

1994-01-01

Explant organ culture was used to demonstrate that isolated embryonic mouse pre-metatarsal mesenchyme is capable of undergoing a series of differentiative and morphogenetic developmental events. Mesenchyme differentiation into chondrocytes, and concurrent morphogenetic patterning of the cartilage tissue, and terminal chondrocyte differentiation with subsequent matrix mineralization show that cultured tissue closely parallels in vivo development. Whole mount alizarin red staining of the cultured tissue demonstrates that the extracellular matrix around the hypertrophied chondrocytes is competent to support mineralization. Intensely stained mineralized bands are similar to those formed in pre-metatarsals developing in vivo. We have adapted the culture strategy for experimentation in a reduced gravity environment on the Space Shuttle. Spaceflight culture of pre-metatarsals, which have already initiated chondrogenesis and morphogenetic patterning, results in an increase in cartilage rod size and maintenance of rod shape, compared to controls. Older pre-metatarsal tissue, already terminally differentiated to hypertrophied cartilage, maintained rod structure and cartilage phenotype during spaceflight culture.

Determining the imaging plane of a retinal capillary layer in adaptive optical imaging

NASA Astrophysics Data System (ADS)

Yang, Le-Bao; Hu, Li-Fa; Li, Da-Yu; Cao, Zhao-Liang; Mu, Quan-Quan; Ma, Ji; Xuan, Li

2016-09-01

Even in the early stage, endocrine metabolism disease may lead to micro aneurysms in retinal capillaries whose diameters are less than 10 μm. However, the fundus cameras used in clinic diagnosis can only obtain images of vessels larger than 20 μm in diameter. The human retina is a thin and multiple layer tissue, and the layer of capillaries less than 10 μm in diameter only exists in the inner nuclear layer. The layer thickness of capillaries less than 10 μm in diameter is about 40 μm and the distance range to rod&cone cell surface is tens of micrometers, which varies from person to person. Therefore, determining reasonable capillary layer (CL) position in different human eyes is very difficult. In this paper, we propose a method to determine the position of retinal CL based on the rod&cone cell layer. The public positions of CL are recognized with 15 subjects from 40 to 59 years old, and the imaging planes of CL are calculated by the effective focal length of the human eye. High resolution retinal capillary imaging results obtained from 17 subjects with a liquid crystal adaptive optics system (LCAOS) validate our method. All of the subjects’ CLs have public positions from 127 μm to 147 μm from the rod&cone cell layer, which is influenced by the depth of focus. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174274, 11174279, 61205021, 11204299, 61475152, and 61405194).

Shifts in Selective Pressures on Snake Phototransduction Genes Associated with Photoreceptor Transmutation and Dim-Light Ancestry.

PubMed

Schott, Ryan K; Van Nynatten, Alexander; Card, Daren C; Castoe, Todd A; S W Chang, Belinda

2018-06-01

The visual systems of snakes are heavily modified relative to other squamates, a condition often thought to reflect their fossorial origins. Further modifications are seen in caenophidian snakes, where evolutionary transitions between rod and cone photoreceptors, termed photoreceptor transmutations, have occurred in many lineages. Little previous work, however, has focused on the molecular evolutionary underpinnings of these morphological changes. To address this, we sequenced seven snake eye transcriptomes and utilized new whole-genome and targeted capture sequencing data. We used these data to analyze gene loss and shifts in selection pressures in phototransduction genes that may be associated with snake evolutionary origins and photoreceptor transmutation. We identified the surprising loss of rhodopsin kinase (GRK1), despite a low degree of gene loss overall and a lack of relaxed selection early during snake evolution. These results provide some of the first evolutionary genomic corroboration for a dim-light ancestor that lacks strong fossorial adaptations. Our results also indicate that snakes with photoreceptor transmutation experienced significantly different selection pressures from other reptiles. Significant positive selection was found primarily in cone-specific genes, but not rod-specific genes, contrary to our expectations. These results reveal potential molecular adaptations associated with photoreceptor transmutation and also highlight unappreciated functional differences between rod- and cone-specific phototransduction proteins. This intriguing example of snake visual system evolution illustrates how the underlying molecular components of a complex system can be reshaped in response to changing selection pressures.

HEALTH CONDITIONS LINKED TO AGE-RELATED MACULAR DEGENERATION ASSOCIATED WITH DARK ADAPTATION.

PubMed

Laíns, Inês; Miller, John B; Mukai, Ryo; Mach, Steven; Vavvas, Demetrios; Kim, Ivana K; Miller, Joan W; Husain, Deeba

2018-06-01

To determine the association between dark adaption (DA) and different health conditions linked with age-related macular degeneration (AMD). Cross-sectional study, including patients with AMD and a control group. Age-related macular degeneration was graded according to the Age-Related Eye Disease Study (AREDS) classification. We obtained data on medical history, medications, and lifestyle. Dark adaption was assessed with the extended protocol (20 minutes) of AdaptDx (MacuLogix). For analyses, the right eye or the eye with more advanced AMD was selected. Multivariate linear and logistic regressions were performed, accounting for age and AMD stage. Seventy-eight subjects (75.6% AMD; 24.4% controls) were included. Multivariate assessments revealed that body mass index (BMI; β = 0.30, P = 0.045), taking AREDS vitamins (β = 5.51, P < 0.001), and family history of AMD (β = 2.68, P = 0.039) were significantly associated with worse rod intercept times. Abnormal DA (rod intercept time ≥ 6.5 minutes) was significantly associated with family history of AMD (β = 1.84, P = 0.006), taking AREDS supplements (β = 1.67, P = 0.021) and alcohol intake (β = 0.07, P = 0.017). Besides age and AMD stage, a higher body mass index, higher alcohol intake, and a family history of AMD seem to impair DA. In this cohort, the use of AREDS vitamins was also statistically linked with impaired DA, most likely because of an increased severity of disease in subjects taking them.

RECOVERY OF ROD PHOTORESPONSES IN ABCR-DEFICIENT MICE

PubMed Central

Pawar, Ambarish S.; Qtaishat, Nasser M.; Little, Deborah M.; Pepperberg, David R.

2010-01-01

Purpose ABCR protein in the rod outer segment is thought to facilitate movement of the all-trans retinal photoproduct of rhodopsin bleaching out of the disk lumen. We investigated the extent to which ABCR deficiency affects post-bleach recovery of the rod photoresponse in ABCR-deficient (abcr−/−) mice. Methods Electroretinographic (ERG) a-wave responses were recorded from abcr−/− mice and two control strains. Using a bright probe flash, we examined the course of rod recovery following fractional rhodopsin bleaches of ~10−6, ~3×10−5, ~0.03 and ~0.30–0.40. Results Dark-adapted abcr−/− mice and controls exhibited similar normalized near-peak amplitudes of the paired-flash-ERG-derived, weak-flash response. Response recovery following ~10−6 bleaching exhibited an average exponential time constant of 319, 171 and 213 ms, respectively, in the abcr−/− and the two control strains. Recovery time constants determined for ~3×10−5 bleaching did not differ significantly among strains. However, those determined for the ~0.03 bleach indicated significantly faster recovery in abcr−/− (2.34 ± 0.74 min) than in the controls (5.36 ± 2.20 min, and 5.92 ± 2.44 min). Following ~0.30–0.40 bleaching, the initial recovery in the abcr−/− was on average faster than in controls. Conclusions By comparison with controls, abcr−/− mice exhibit faster rod recovery following a bleach of ~0.03. The data suggest that ABCR in normal rods may directly or indirectly prolong all-trans retinal clearance from the disk lumen over a significant bleaching range, and that the essential function of ABCR may be to promote the clearance of residual amounts of all-trans retinal that remain in the disks long after bleaching. PMID:18263807

Rod- and cone-driven responses in mice expressing human L-cone pigment

PubMed Central

Atorf, Jenny; Neitz, Maureen; Neitz, Jay

2015-01-01

The mouse is commonly used for studying retinal processing, primarily because it is amenable to genetic manipulation. To accurately study photoreceptor driven signals in the healthy and diseased retina, it is of great importance to isolate the responses of single photoreceptor types. This is not easily achieved in mice because of the strong overlap of rod and M-cone absorption spectra (i.e., maxima at 498 and 508 nm, respectively). With a newly developed mouse model (Opn1lwLIAIS) expressing a variant of the human L-cone pigment (561 nm) instead of the mouse M-opsin, the absorption spectra are substantially separated, allowing retinal physiology to be studied using silent substitution stimuli. Unlike conventional chromatic isolation methods, this spectral compensation approach can isolate single photoreceptor subtypes without changing the retinal adaptation. We measured flicker electroretinograms in these mutants under ketamine-xylazine sedation with double silent substitution (silent S-cone and either rod or M/L-cones) and obtained robust responses for both rods and (L-)cones. Small signals were yielded in wild-type mice, whereas heterozygotes exhibited responses that were generally intermediate to both. Fundamental response amplitudes and phase behaviors (as a function of temporal frequency) in all genotypes were largely similar. Surprisingly, isolated (L-)cone and rod response properties in the mutant strain were alike. Thus the LIAIS mouse warrants a more comprehensive in vivo assessment of photoreceptor subtype-specific physiology, because it overcomes the hindrance of overlapping spectral sensitivities present in the normal mouse. PMID:26245314

Adaptive behaviour and motor skills in children with upper limb deficiency.

PubMed

Mano, Hiroshi; Fujiwara, Sayaka; Haga, Nobuhiko

2018-04-01

The dysfunction of individuals with upper limb deficiencies affects their daily lives and social participation. To clarify the adaptive behaviours and motor skills of children with upper limb deficiencies. Cross-sectional survey. The subjects were 10 children ranging from 1 to 6 years of age with unilateral upper limb deficiencies at the level distal to the elbow who were using only cosmetic or passive prostheses or none at all. To measure their adaptive behaviour and motor skills, the Vineland Adaptive Behavior Scales, Second Edition was used. They were evaluated on the domains of communication, daily living skills, socialization and motor skills. We also examined the relationship of the scores with age. There were no statistically significant scores for domains or subdomains. The domain standard score of motor skills was significantly lower than the median scores of the domains and was negatively correlated with age. Children with upper limb deficiencies have individual weaknesses in motor skill behaviours, and these weaknesses increase with age. It may be helpful in considering approaches to rehabilitation and the prescription of prostheses to consider the characteristics and course of children's motor skill behaviours. Clinical relevance Even if children with unilateral upper limb deficiencies seem to compensate well for their affected limb function, they have or will experience individual weaknesses in motor skills. We should take this into consideration to develop better strategies for rehabilitation and prostheses prescriptions.

Müller glial cells contribute to dim light vision in the spectacled caiman (Caiman crocodilus fuscus): Analysis of retinal light transmission.

PubMed

Agte, Silke; Savvinov, Alexey; Karl, Anett; Zayas-Santiago, Astrid; Ulbricht, Elke; Makarov, Vladimir I; Reichenbach, Andreas; Bringmann, Andreas; Skatchkov, Serguei N

2018-05-16

In this study, we show the capability of Müller glial cells to transport light through the inverted retina of reptiles, specifically the retina of the spectacled caimans. Thus, confirming that Müller cells of lower vertebrates also improve retinal light transmission. Confocal imaging of freshly isolated retinal wholemounts, that preserved the refractive index landscape of the tissue, indicated that the retina of the spectacled caiman is adapted for vision under dim light conditions. For light transmission experiments, we used a setup with two axially aligned objectives imaging the retina from both sides to project the light onto the inner (vitreal) surface and to detect the transmitted light behind the retina at the receptor layer. Simultaneously, a confocal microscope obtained images of the Müller cells embedded within the vital tissue. Projections of light onto several representative Müller cell trunks within the inner plexiform layer, i.e. (i) trunks with a straight orientation, (ii) trunks which are formed by the inner processes and (iii) trunks which get split into inner processes, were associated with increases in the intensity of the transmitted light. Projections of light onto the periphery of the Müller cell endfeet resulted in a lower intensity of transmitted light. In this way, retinal glial (Müller) cells support dim light vision by improving the signal-to-noise ratio which increases the sensitivity to light. The field of illuminated photoreceptors mainly include rods reflecting the rod dominance of the of tissue. A subpopulation of Müller cells with downstreaming cone cells led to a high-intensity illumination of the cones, while the surrounding rods were illuminated by light of lower intensity. Therefore, Müller cells that lie in front of cones may adapt the intensity of the transmitted light to the different sensitivities of cones and rods, presumably allowing a simultaneous vision with both receptor types under dim light conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Genetic Dissection of Dual Roles for the Transcription Factor six7 in Photoreceptor Development and Patterning in Zebrafish

PubMed Central

Sotolongo-Lopez, Mailin; Alvarez-Delfin, Karen; Saade, Carole J.; Vera, Daniel L.; Fadool, James M.

2016-01-01

The visual system of a particular species is highly adapted to convey detailed ecological and behavioral information essential for survival. The consequences of structural mutations of opsins upon spectral sensitivity and environmental adaptation have been studied in great detail, but lacking is knowledge of the potential influence of alterations in gene regulatory networks upon the diversity of cone subtypes and the variation in the ratio of rods and cones observed in numerous diurnal and nocturnal species. Exploiting photoreceptor patterning in cone-dominated zebrafish, we uncovered two independent mechanisms by which the sine oculis homeobox homolog 7 (six7) regulates photoreceptor development. In a genetic screen, we isolated the lots-of-rods-junior (ljrp23ahub) mutation that resulted in an increased number and uniform distribution of rods in otherwise normal appearing larvae. Sequence analysis, genome editing using TALENs and knockdown strategies confirm ljrp23ahub as a hypomorphic allele of six7, a teleost orthologue of six3, with known roles in forebrain patterning and expression of opsins. Based on the lack of predicted protein-coding changes and a deletion of a conserved element upstream of the transcription start site, a cis-regulatory mutation is proposed as the basis of the reduced expression of six7 in ljrp23ahub. Comparison of the phenotypes of the hypomorphic and knock-out alleles provides evidence of two independent roles in photoreceptor development. EdU and PH3 labeling show that the increase in rod number is associated with extended mitosis of photoreceptor progenitors, and TUNEL suggests that the lack of green-sensitive cones is the result of cell death of the cone precursor. These data add six7 to the small but growing list of essential genes for specification and patterning of photoreceptors in non-mammalian vertebrates, and highlight alterations in transcriptional regulation as a potential source of photoreceptor variation across species. PMID:27058886

A Simple Mechanical Experiment on Exponential Growth

ERIC Educational Resources Information Center

McGrew, Ralph

2015-01-01

With a rod, cord, pulleys, and slotted masses, students can observe and graph exponential growth in the cord tension over a factor of increase as large as several hundred. This experiment is adaptable for use either in algebra-based or calculus-based physics courses, fitting naturally with the study of sliding friction. Significant parts of the…

Multiple rod–cone and cone–rod photoreceptor transmutations in snakes: Evidence from visual opsin gene expression

USGS Publications Warehouse

Simoe, Bruno F; Sampaio, Filipa L.; Loew, Ellis R.; Sanders, Kate L.; Fisher, Robert N.; Hart, Nathan S.; Hunt, David M.; Partridge, Julian C.; Gower, David J.

2016-01-01

In 1934, Gordon Walls forwarded his radical theory of retinal photoreceptor ‘transmutation’. This proposed that rods and cones used for scotopic and photopic vision, respectively, were not fixed but could evolve into each other via a series of morphologically distinguishable intermediates. Walls' prime evidence came from series of diurnal and nocturnal geckos and snakes that appeared to have pure-cone or pure-rod retinas (in forms that Walls believed evolved from ancestors with the reverse complement) or which possessed intermediate photoreceptor cells. Walls was limited in testing his theory because the precise identity of visual pigments present in photoreceptors was then unknown. Subsequent molecular research has hitherto neglected this topic but presents new opportunities. We identify three visual opsin genes, rh1, sws1 and lws, in retinal mRNA of an ecologically and taxonomically diverse sample of snakes central to Walls' theory. We conclude that photoreceptors with superficially rod- or cone-like morphology are not limited to containing scotopic or photopic opsins, respectively. Walls' theory is essentially correct, and more research is needed to identify the patterns, processes and functional implications of transmutation. Future research will help to clarify the fundamental properties and physiology of photoreceptors adapted to function in different light levels.

Multiple rod–cone and cone–rod photoreceptor transmutations in snakes: evidence from visual opsin gene expression

PubMed Central

Sampaio, Filipa L.; Loew, Ellis R.; Sanders, Kate L.; Fisher, Robert N.; Hart, Nathan S.; Hunt, David M.; Partridge, Julian C.

2016-01-01

In 1934, Gordon Walls forwarded his radical theory of retinal photoreceptor ‘transmutation’. This proposed that rods and cones used for scotopic and photopic vision, respectively, were not fixed but could evolve into each other via a series of morphologically distinguishable intermediates. Walls' prime evidence came from series of diurnal and nocturnal geckos and snakes that appeared to have pure-cone or pure-rod retinas (in forms that Walls believed evolved from ancestors with the reverse complement) or which possessed intermediate photoreceptor cells. Walls was limited in testing his theory because the precise identity of visual pigments present in photoreceptors was then unknown. Subsequent molecular research has hitherto neglected this topic but presents new opportunities. We identify three visual opsin genes, rh1, sws1 and lws, in retinal mRNA of an ecologically and taxonomically diverse sample of snakes central to Walls' theory. We conclude that photoreceptors with superficially rod- or cone-like morphology are not limited to containing scotopic or photopic opsins, respectively. Walls' theory is essentially correct, and more research is needed to identify the patterns, processes and functional implications of transmutation. Future research will help to clarify the fundamental properties and physiology of photoreceptors adapted to function in different light levels. PMID:26817768

TRAC-PD2 posttest analysis of CCTF Test C1-16 (Run 025). [Cylindrical Core Test Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugimoto, J.

The TRAC-PD2 code version was used to analyze CCTF Test C1-16 (Run 025). The results indicate that the core heater rod temperatures, the liquid mass in the vessel, and differential pressures in the primary loop are predicted well, but the void fraction distribution in the core and water accumulation in the upper plenum are not in good agreement with the data.

Backstepping Design of Adaptive Neural Fault-Tolerant Control for MIMO Nonlinear Systems.

PubMed

Gao, Hui; Song, Yongduan; Wen, Changyun

In this paper, an adaptive controller is developed for a class of multi-input and multioutput nonlinear systems with neural networks (NNs) used as a modeling tool. It is shown that all the signals in the closed-loop system with the proposed adaptive neural controller are globally uniformly bounded for any external input in . In our control design, the upper bound of the NN modeling error and the gains of external disturbance are characterized by unknown upper bounds, which is more rational to establish the stability in the adaptive NN control. Filter-based modification terms are used in the update laws of unknown parameters to improve the transient performance. Finally, fault-tolerant control is developed to accommodate actuator failure. An illustrative example applying the adaptive controller to control a rigid robot arm shows the validation of the proposed controller.In this paper, an adaptive controller is developed for a class of multi-input and multioutput nonlinear systems with neural networks (NNs) used as a modeling tool. It is shown that all the signals in the closed-loop system with the proposed adaptive neural controller are globally uniformly bounded for any external input in . In our control design, the upper bound of the NN modeling error and the gains of external disturbance are characterized by unknown upper bounds, which is more rational to establish the stability in the adaptive NN control. Filter-based modification terms are used in the update laws of unknown parameters to improve the transient performance. Finally, fault-tolerant control is developed to accommodate actuator failure. An illustrative example applying the adaptive controller to control a rigid robot arm shows the validation of the proposed controller.

Lens based adaptive optics scanning laser ophthalmoscope.

PubMed

Felberer, Franz; Kroisamer, Julia-Sophie; Hitzenberger, Christoph K; Pircher, Michael

2012-07-30

We present an alternative approach for an adaptive optics scanning laser ophthalmoscope (AO-SLO). In contrast to other commonly used AO-SLO instruments, the imaging optics consist of lenses. Images of the fovea region of 5 healthy volunteers are recorded. The system is capable to resolve human foveal cones in 3 out of 5 healthy volunteers. Additionally, we investigated the capability of the system to support larger scanning angles (up to 5°) on the retina. Finally, in order to demonstrate the performance of the instrument images of rod photoreceptors are presented.

Photoreceptor Layer Thickness Changes During Dark Adaptation Observed With Ultrahigh-Resolution Optical Coherence Tomography.

PubMed

Lu, Chen D; Lee, ByungKun; Schottenhamml, Julia; Maier, Andreas; Pugh, Edward N; Fujimoto, James G

2017-09-01

To examine outer retinal band changes after flash stimulus and subsequent dark adaptation with ultrahigh-resolution optical coherence tomography (UHR-OCT). Five dark-adapted left eyes of five normal subjects were imaged with 3-μm axial-resolution UHR-OCT during 30 minutes of dark adaptation following 96%, 54%, 23%, and 0% full-field and 54% half-field rhodopsin bleach. We identified the ellipsoid zone inner segment/outer segment (EZ[IS/OS]), cone interdigitation zone (CIZ), rod interdigitation zone (RIZ), retinal pigment epithelium (RPE), and Bruch's membrane (BM) axial positions and generated two-dimensional thickness maps of the EZ(IS/OS) to the four bands. The average thickness over an area of the thickness map was compared against that of the dark-adapted baselines. The time-dependent thickness changes (photoresponses) were statistically compared against 0% bleach. Dark adaptometry was performed with the same bleaching protocol. The EZ(IS/OS)-CIZ photoresponse was significantly different at 96% (P < 0.0001) and 54% (P = 0.006) bleach. At all three bleaching levels, the EZ(IS/OS)-RIZ, -RPE, and -BM responses were significantly different (P < 0.0001). The EZ(IS/OS)-CIZ and EZ(IS/OS)-RIZ time courses were similar to the recovery of rod- and cone-mediated sensitivity, respectively, measured with dark adaptometry. The maximal EZ(IS/OS)-CIZ and EZ(IS/OS)-RIZ response magnitudes doubled from 54% to 96% bleach. Both EZ(IS/OS)-RPE and EZ(IS/OS)-BM responses resembled dampened oscillations that were graded in amplitude and duration with bleaching intensity. Half-field photoresponses were localized to the stimulated retina. With noninvasive, near-infrared UHR-OCT, we characterized three distinct, spatially localized photoresponses in the outer retinal bands. These photoresponses have potential value as physical correlates of photoreceptor function.

Enhancing the ABAQUS Thermomechanics Code to Simulate Steady and Transient Fuel Rod Behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. L. Williamson; D. A. Knoll

2009-09-01

A powerful multidimensional fuels performance capability, applicable to both steady and transient fuel behavior, is developed based on enhancements to the commercially available ABAQUS general-purpose thermomechanics code. Enhanced capabilities are described, including: UO2 temperature and burnup dependent thermal properties, solid and gaseous fission product swelling, fuel densification, fission gas release, cladding thermal and irradiation creep, cladding irradiation growth , gap heat transfer, and gap/plenum gas behavior during irradiation. The various modeling capabilities are demonstrated using a 2D axisymmetric analysis of the upper section of a simplified multi-pellet fuel rod, during both steady and transient operation. Computational results demonstrate the importancemore » of a multidimensional fully-coupled thermomechanics treatment. Interestingly, many of the inherent deficiencies in existing fuel performance codes (e.g., 1D thermomechanics, loose thermo-mechanical coupling, separate steady and transient analysis, cumbersome pre- and post-processing) are, in fact, ABAQUS strengths.« less

Mineralized rods and cones suggest colour vision in a 300 Myr-old fossil fish.

PubMed

Tanaka, Gengo; Parker, Andrew R; Hasegawa, Yoshikazu; Siveter, David J; Yamamoto, Ryoichi; Miyashita, Kiyoshi; Takahashi, Yuichi; Ito, Shosuke; Wakamatsu, Kazumasa; Mukuda, Takao; Matsuura, Marie; Tomikawa, Ko; Furutani, Masumi; Suzuki, Kayo; Maeda, Haruyoshi

2014-12-23

Vision, which consists of an optical system, receptors and image-processing capacity, has existed for at least 520 Myr. Except for the optical system, as in the calcified lenses of trilobite and ostracod arthropods, other parts of the visual system are not usually preserved in the fossil record, because the soft tissue of the eye and the brain decay rapidly after death, such as within 64 days and 11 days, respectively. The Upper Carboniferous Hamilton Formation (300 Myr) in Kansas, USA, yields exceptionally well-preserved animal fossils in an estuarine depositional setting. Here we show that the original colour, shape and putative presence of eumelanin have been preserved in the acanthodii fish Acanthodes bridgei. We also report on the tissues of its eye, which provides the first record of mineralized rods and cones in a fossil and indicates that this 300 Myr-old fish likely possessed colour vision.

Lower-upper-threshold correlation for underwater range-gated imaging self-adaptive enhancement.

PubMed

Sun, Liang; Wang, Xinwei; Liu, Xiaoquan; Ren, Pengdao; Lei, Pingshun; He, Jun; Fan, Songtao; Zhou, Yan; Liu, Yuliang

2016-10-10

In underwater range-gated imaging (URGI), enhancement of low-brightness and low-contrast images is critical for human observation. Traditional histogram equalizations over-enhance images, with the result of details being lost. To compress over-enhancement, a lower-upper-threshold correlation method is proposed for underwater range-gated imaging self-adaptive enhancement based on double-plateau histogram equalization. The lower threshold determines image details and compresses over-enhancement. It is correlated with the upper threshold. First, the upper threshold is updated by searching for the local maximum in real time, and then the lower threshold is calculated by the upper threshold and the number of nonzero units selected from a filtered histogram. With this method, the backgrounds of underwater images are constrained with enhanced details. Finally, the proof experiments are performed. Peak signal-to-noise-ratio, variance, contrast, and human visual properties are used to evaluate the objective quality of the global and regions of interest images. The evaluation results demonstrate that the proposed method adaptively selects the proper upper and lower thresholds under different conditions. The proposed method contributes to URGI with effective image enhancement for human eyes.

Effect of indocyanine green angiography using infrared fundus camera on subsequent dark adaptation and electroretinogram.

PubMed

Wen, Feng; Yu, Minzhong; Wu, Dezheng; Ma, Juanmei; Wu, Lezheng

2002-07-01

To observe the effect of indocyanine green angiography (ICGA) with infrared fundus camera on subsequent dark adaptation and the Ganzfeld electroretinogram (ERG), the ERGs of 38 eyes with different retinal diseases were recorded before and after ICGA during a 40-min dark adaptation period. ICGA was performed with Topcon 50IA retina camera. Ganzfeld ERG was recorded with Neuropack II evoked response recorder. The results showed that ICGA did not affect the latencies and the amplitudes in ERG of rod response, cone response and mixed maximum response (p>0.05). It suggests that ICGA using infrared fundus camera could be performed prior to the recording of the Ganzfeld ERG.

Holder for rotating glass body

DOEpatents

Kolleck, Floyd W.

1978-04-04

A device is provided for holding and centering a rotating glass body such as a rod or tube. The device includes a tubular tip holder which may be held in a lathe chuck. The device can utilize a variety of centering tips each adapted for a particular configuration, such as a glass O-ring joint or semi-ball joint.

Insensitive Munitions (Les Munitions a Risque Attenue)

DTIC Science & Technology

1992-07-01

hydrocar- a banana plug connector attached to the bon and silicone oils resulted in such a high ground wire that would be attached during friction load...had a banana diameter upper electrode rod passed through plug connector attached to the high voltage the nylon insulator. It was much longer (350...mm deep so that it hole was put through the center of the could accept a banana plug attached to the propellant contact to enable acceptance of a

Evidence of incomplete annealing at 800 °C and the effects of 120 °C baking on the crystal orientation and the surface superconducting properties of cold-worked and chemically polished Nb

NASA Astrophysics Data System (ADS)

Sung, Z.-H.; Dzyuba, A.; Lee, P. J.; Larbalestier, D. C.; Cooley, L. D.

2015-07-01

High-purity niobium rods were cold-worked by wire-drawing, followed by various combinations of chemical polishing and high-vacuum baking at 120 °C or annealing at 800 °C in order to better understand changes to the surface superconducting properties resulting from typical superconducting radio-frequency cavity processing. AC susceptibility measurements revealed an enhanced upper transition Tc at ˜ 9.3-9.4 K in all samples that was stable through all annealing steps, a value significantly above the accepted Tc of 9.23 K for pure annealed niobium. Corresponding elevations were seen in the critical fields, the ratio of the surface critical field Hc3 to the bulk upper critical field Hc2 rising to 2.3, well above the Ginzburg-Landau value of 1.695. Orientation imaging revealed an extensive dislocation rich sub-grain structure in the as-drawn rods, a small reduction of the surface strain after baking at 120 °C, and a substantial but incomplete recrystallization near the surface after annealing at 800 °C. We interpret these changes in surface superconducting and structural properties to extensive changes in the near-surface interstitial contamination produced by baking and annealing and to synergistic interactions between H and surface O introduced during electropolishing and buffered chemical polishing.

GUCY2D Cone-Rod Dystrophy-6 Is a "Phototransduction Disease" Triggered by Abnormal Calcium Feedback on Retinal Membrane Guanylyl Cyclase 1.

PubMed

Sato, Shinya; Peshenko, Igor V; Olshevskaya, Elena V; Kefalov, Vladimir J; Dizhoor, Alexander M

2018-03-21

The Arg838Ser mutation in retinal membrane guanylyl cyclase 1 (RetGC1) has been linked to autosomal dominant cone-rod dystrophy type 6 (CORD6). It is believed that photoreceptor degeneration is caused by the altered sensitivity of RetGC1 to calcium regulation via guanylyl cyclase activating proteins (GCAPs). To determine the mechanism by which this mutation leads to degeneration, we investigated the structure and function of rod photoreceptors in two transgenic mouse lines, 362 and 379, expressing R838S RetGC1. In both lines, rod outer segments became shorter than in their nontransgenic siblings by 3-4 weeks of age, before the eventual photoreceptor degeneration. Despite the shortening of their outer segments, the dark current of transgenic rods was 1.5-2.2-fold higher than in nontransgenic controls. Similarly, the dim flash response amplitude in R838S + rods was larger, time to peak was delayed, and flash sensitivity was increased, all suggesting elevated dark-adapted free cGMP in transgenic rods. In rods expressing R838S RetGC1, dark-current noise increased and the exchange current, detected after a saturating flash, became more pronounced. These results suggest disrupted Ca 2+ phototransduction feedback and abnormally high free-Ca 2+ concentration in the outer segments. Notably, photoreceptor degeneration, which typically occurred after 3 months of age in R838S RetGC1 transgenic mice in GCAP1,2 +/+ or GCAP1,2 +/- backgrounds, was prevented in GCAP1,2 -/- mice lacking Ca 2+ feedback to guanylyl cyclase. In summary, the dysregulation of guanylyl cyclase in RetGC1-linked CORD6 is a "phototransduction disease," which means it is associated with increased free-cGMP and Ca 2+ levels in photoreceptors. SIGNIFICANCE STATEMENT In a mouse model expressing human membrane guanylyl cyclase 1 (RetGC1, GUCY2D ), a mutation associated with early progressing congenital blindness, cone-rod dystrophy type 6 (CORD6), deregulates calcium-sensitive feedback of phototransduction to the cyclase mediated by guanylyl cyclase activating proteins (GCAPs), which are calcium-sensor proteins. The abnormal calcium sensitivity of the cyclase increases cGMP-gated dark current in the rod outer segments, reshapes rod photoresponses, and triggers photoreceptor death. This work is the first to demonstrate a direct physiological effect of GUCY2D CORD6-linked mutation on photoreceptor physiology in vivo It also identifies the abnormal regulation of the cyclase by calcium-sensor proteins as the main trigger for the photoreceptor death. Copyright © 2018 the authors 0270-6474/18/382990-11$15.00/0.

Diagnostic Sensitivity and Specificity of Dark Adaptometry for Detection of Age-Related Macular Degeneration

PubMed Central

Jackson, Gregory R.; Scott, Ingrid U.; Kim, Ivana K.; Quillen, David A.; Iannaccone, Alessandro; Edwards, John G.

2014-01-01

Purpose. Difficulty with night vision is a common complaint of patients with age-related macular degeneration (AMD). Consistent with this complaint, dark adaptation (DA) is substantially impaired in these patients. Because of the severity of the deficit, measurement of DA has been suggested as a means for the diagnosis of AMD. Previous methods for measurement of DA were time intensive (>30 minutes), which made them unsuitable for clinical use. This study evaluated a rapid DA test (≤6.5 minutes) for the detection of AMD. Methods. Dark adaptation was measured by using the AdaptDx dark adaptometer in two groups: subjects with normal retinal health and subjects with AMD. Subjects were assigned to their group by clinical examination and grading of fundus photographs. Subjects were classified as having DA consistent with normal retinal health (rod intercept ≤ 6.5 minutes) or having dark adaptation consistent with AMD (rod intercept > 6.5 minutes). Results. The eligible sample for analysis included 21 normal adults and 127 AMD patients. The rapid test was found to have a diagnostic sensitivity of 90.6% (P < 0.001) and specificity of 90.5% (P < 0.027). Thus, abnormal DA was detected in 115 of 127 AMD patients, and normal DA was found in 19 of 21 normal adults. Conclusions. The high diagnostic sensitivity and specificity compared favorably to long-duration research methods for the measurement of DA, and slit lamp biomicroscopy performed by a retina specialist. These results suggest that a rapid DA test is useful for the detection of AMD. PMID:24550363

Regression of early diabetic macular oedema is associated with prevention of dark adaptation

PubMed Central

Arden, G B; Jyothi, S; Hogg, C H; Lee, Y F; Sivaprasad, S

2011-01-01

Hypothesis Dark-adapted rods consume oxygen at high rates and light adaptation decreases this oxygen burden and can have therapeutic effects on diabetic macular oedema (DMO). Methods Patients with mild non-proliferative diabetic retinopathy (DR) and early, untreated non-sight-threatening DMO slept for 6 months wearing masks that illuminated the eyelid of one closed eye by 505 nm light. Exclusion criteria were any concomitant eye disease, DR >ETDRS grade 35, and other systemic diseases. Primary outcome: change of OCT retinal thickness in the local region where oedema was present. Results A total of 34 out of 40 patients completed the study. Mean baseline OCT macular cube thickness was equivalent for study and fellow eyes. But study eyes had a greater mean thickness in the central subfield zone 1 (282±53 μm) vs (256±19 μm) the fellow eyes. Twenty-eight study eyes showed intraretinal cysts compared with nine in the fellow eyes. At 6 months, only 19 study eyes had cysts while cysts were seen in 20 fellow eyes. After 6 months, the worst affected ETDRS zone and the central subfield zone 1 reduced in thickness in study eyes only by 12 μm (95% CI 20 to −7, P=0.01). The secondary outcomes of change in visual acuity, achromatic contrast sensitivity, and microperimetric thresholds improved significantly in study eyes and deteriorated in fellow eyes. Conclusions Sleeping in dim light that can keep rods light adapted may reverse the changes of DMO. PMID:22020171

Nuclear reactor

DOEpatents

Pennell, William E.; Rowan, William J.

1977-01-01

A nuclear reactor in which the core components, including fuel-rod assemblies, control-rod assemblies, fertile rod-assemblies, and removable shielding assemblies, are supported by a plurality of separate inlet modular units. These units are referred to as inlet module units to distinguish them from the modules of the upper internals of the reactor. The modular units are supported, each removable independently of the others, in liners in the supporting structure for the lower internals of the reactor. The core assemblies are removably supported in integral receptacles or sockets of the modular units. The liners, units, sockets and assmblies have inlet openings for entry of the fluid. The modular units are each removably mounted in the liners with fluid seals interposed between the opening in the liner and inlet module into which the fluid enters and the upper and lower portion of the liner. Each assembly is similarly mounted in a corresponding receptacle with fluid seals interposed between the openings where the fluid enters and the lower portion of the receptacle or fitting closely in these regions. As fluid flows along each core assembly a pressure drop is produced along the fluid so that the fluid which emerges from each core assembly is at a lower pressure than the fluid which enters the core assembly. However because of the seals interposed in the mountings of the units and assemblies the pressures above and below the units and assemblies are balanced and the units are held in the liners and the assemblies are held in the receptacles by their weights as they have a higher specific gravity than the fluid. The low-pressure spaces between each module and its liner and between each core assembly and its module is vented to the low-pressure regions of the vessel to assure that fluid which leaks through the seals does not accumulate and destroy the hydraulic balance.

Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod.

PubMed

Schwing, Patrick T; Romero, Isabel C; Larson, Rebekka A; O'Malley, Bryan J; Fridrik, Erika E; Goddard, Ethan A; Brooks, Gregg R; Hastings, David W; Rosenheim, Brad E; Hollander, David J; Grant, Guy; Mulhollan, Jim

2016-08-17

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aquatic sediment cores of varying diameters. Millimeter scale subsampling allows for sub-annual to monthly analysis of the sedimentary record, an order of magnitude higher than typical sampling schemes. The extruder consists of a 2 m aluminum frame and base, two core tube clamps, a threaded-rod, and a 1 m piston. The sediment core is placed above the piston and clamped to the frame. An acrylic sampling collar is affixed to the upper 5 cm of the core tube and provides a platform from which to extract sub-samples. The piston is rotated around the threaded-rod at calibrated intervals and gently pushes the sediment out the top of the core tube. The sediment is then isolated into the sampling collar and placed into an appropriate sampling vessel (e.g., jar or bag). This method also preserves the unconsolidated samples (i.e., high pore water content) at the surface, providing a consistent sampling volume. This mm scale extrusion method was applied to cores collected in the northern Gulf of Mexico following the Deepwater Horizon submarine oil release. Evidence suggests that it is necessary to sample at the mm scale to fully characterize events that occur on the monthly time-scale for continental slope sediments.

Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod

PubMed Central

Schwing, Patrick T.; Romero, Isabel C.; Larson, Rebekka A.; O'Malley, Bryan J.; Fridrik, Erika E.; Goddard, Ethan A.; Brooks, Gregg R.; Hastings, David W.; Rosenheim, Brad E.; Hollander, David J.; Grant, Guy; Mulhollan, Jim

2016-01-01

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aquatic sediment cores of varying diameters. Millimeter scale subsampling allows for sub-annual to monthly analysis of the sedimentary record, an order of magnitude higher than typical sampling schemes. The extruder consists of a 2 m aluminum frame and base, two core tube clamps, a threaded-rod, and a 1 m piston. The sediment core is placed above the piston and clamped to the frame. An acrylic sampling collar is affixed to the upper 5 cm of the core tube and provides a platform from which to extract sub-samples. The piston is rotated around the threaded-rod at calibrated intervals and gently pushes the sediment out the top of the core tube. The sediment is then isolated into the sampling collar and placed into an appropriate sampling vessel (e.g., jar or bag). This method also preserves the unconsolidated samples (i.e., high pore water content) at the surface, providing a consistent sampling volume. This mm scale extrusion method was applied to cores collected in the northern Gulf of Mexico following the Deepwater Horizon submarine oil release. Evidence suggests that it is necessary to sample at the mm scale to fully characterize events that occur on the monthly time-scale for continental slope sediments. PMID:27585268

Osmolality-dependent relocation of penicillin-binding protein PBP2 to the division site in Caulobacter crescentus.

PubMed

Hocking, Jason; Priyadarshini, Richa; Takacs, Constantin N; Costa, Teresa; Dye, Natalie A; Shapiro, Lucy; Vollmer, Waldemar; Jacobs-Wagner, Christine

2012-06-01

The synthesis of the peptidoglycan cell wall is carefully regulated in time and space. In nature, this essential process occurs in cells that live in fluctuating environments. Here we show that the spatial distributions of specific cell wall proteins in Caulobacter crescentus are sensitive to small external osmotic upshifts. The penicillin-binding protein PBP2, which is commonly branded as an essential cell elongation-specific transpeptidase, switches its localization from a dispersed, patchy pattern to an accumulation at the FtsZ ring location in response to osmotic upshifts as low as 40 mosmol/kg. This osmolality-dependent relocation to the division apparatus is initiated within less than a minute, while restoration to the patchy localization pattern is dependent on cell growth and takes 1 to 2 generations. Cell wall morphogenetic protein RodA and penicillin-binding protein PBP1a also change their spatial distribution by accumulating at the division site in response to external osmotic upshifts. Consistent with its ecological distribution, C. crescentus displays a narrow range of osmotolerance, with an upper limit of 225 mosmol/kg in minimal medium. Collectively, our findings reveal an unsuspected level of environmental regulation of cell wall protein behavior that is likely linked to an ecological adaptation.

Oriented clonal cell dynamics enables accurate growth and shaping of vertebrate cartilage.

PubMed

Kaucka, Marketa; Zikmund, Tomas; Tesarova, Marketa; Gyllborg, Daniel; Hellander, Andreas; Jaros, Josef; Kaiser, Jozef; Petersen, Julian; Szarowska, Bara; Newton, Phillip T; Dyachuk, Vyacheslav; Li, Lei; Qian, Hong; Johansson, Anne-Sofie; Mishina, Yuji; Currie, Joshua D; Tanaka, Elly M; Erickson, Alek; Dudley, Andrew; Brismar, Hjalmar; Southam, Paul; Coen, Enrico; Chen, Min; Weinstein, Lee S; Hampl, Ales; Arenas, Ernest; Chagin, Andrei S; Fried, Kaj; Adameyko, Igor

2017-04-17

Cartilaginous structures are at the core of embryo growth and shaping before the bone forms. Here we report a novel principle of vertebrate cartilage growth that is based on introducing transversally-oriented clones into pre-existing cartilage. This mechanism of growth uncouples the lateral expansion of curved cartilaginous sheets from the control of cartilage thickness, a process which might be the evolutionary mechanism underlying adaptations of facial shape. In rod-shaped cartilage structures (Meckel, ribs and skeletal elements in developing limbs), the transverse integration of clonal columns determines the well-defined diameter and resulting rod-like morphology. We were able to alter cartilage shape by experimentally manipulating clonal geometries. Using in silico modeling, we discovered that anisotropic proliferation might explain cartilage bending and groove formation at the macro-scale.

MEANS FOR CONTROLLING A NUCLEAR REACTOR

DOEpatents

Wilson, V.C.; Overbeck, W.P.; Slotin, L.; Froman, D.K.

1957-12-17

This patent relates to nuclear reactors of the type using a solid neutron absorbing material as a means for controlling the reproduction ratio of the system and thereby the power output. Elongated rods of neutron absorbing material, such as boron steel for example, are adapted to be inserted and removed from the core of tae reactor by electronic motors and suitable drive means. The motors and drive means are controlled by means responsive to the neutron density, such as ionization chambers. The control system is designed to be responsive also to the rate of change in neutron density to automatically maintain the total power output at a substantially constant predetermined value. A safety rod means responsive to neutron density is also provided for keeping the power output below a predetermined maximum value at all times.

Adaptive controller for a strength testbed for aircraft structures

NASA Astrophysics Data System (ADS)

Laperdin, A. I.; Yurkevich, V. D.

2017-07-01

The problem of control system design for a strength testbed of aircraft structures is considered. A method for calculating the parameters of a proportional-integral controller (control algorithm) using the time-scale separation method for the testbed taking into account the dead time effect in the control loop is presented. An adaptive control algorithm structure is proposed which limits the amplitude of high-frequency oscillations in the control system with a change in the direction of motion of the rod of the hydraulic cylinders and provides the desired accuracy and quality of transients at all stages of structural loading history. The results of tests of the developed control system with the adaptive control algorithm on an experimental strength testbed for aircraft structures are given.

Well pump

DOEpatents

Ames, Kenneth R.; Doesburg, James M.

1987-01-01

A well pump includes a piston and an inlet and/or outlet valve assembly of special structure. Each is formed of a body of organic polymer, preferably PTFE. Each includes a cavity in its upper portion and at least one passage leading from the cavity to the bottom of the block. A screen covers each cavity and a valve disk covers each screen. Flexible sealing flanges extend upwardly and downwardly from the periphery of the piston block. The outlet valve block has a sliding block and sealing fit with the piston rod.

Solid State Research.

DTIC Science & Technology

1984-02-15

Diode Lasers 10 - 3. MATERIALS RESEARCH 15 3.1 Role of Oxygen in Zone-Melting Recrystallization of Si Films on Si0 2 -Coated Si Substrates 15 3.2 Triple... Film that Has Been Etch-Delineated to Show Sub- ndaries. Upper Graphite Heater Was Scanned in Direction from top to Bottom of Micrograph. 15 3-2...Operation at 1060 nm with a 5-percent differential power efficiency has been obtained from a flashlamp-pumped laser rod of the sensitized garnet Nd:Cr:Gd 3Sc

Development of an Experimental Test Section for Forcing Unsteady Flow in a Linear Compressor Cascade using Circular Rods

DTIC Science & Technology

2003-03-01

to be moved while the tunnel was running, reducing the need for tunnel shut-down and allowing for thermal equilibrium to be maintained during the high ...rather quickly. However, for the high speed runs, the tunnel heats up greatly, so data cannot be taken until the tunnel reaches thermal steady-state...January 1992. 10. Wilson, David G. and Korakianitis, Theodosius. The Design of High - Efficiency Turbo- machinery and Gas Turbines , 317—322. Upper Saddle

1L Mark-IV Target Design Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koehler, Paul E.

This presentation includes General Design Considerations; Current (Mark-III) Lower Tier; Mark-III Upper Tier; Performance Metrics; General Improvements for Material Science; General Improvements for Nuclear Science; Improving FOM for Nuclear Science; General Design Considerations Summary; Design Optimization Studies; Expected Mark-IV Performance: Material Science; Expected Mark-IV Performance: Nuclear Science (Disk); Mark IV Enables Much Wider Range of Nuclear-Science FOM Gains than Mark III; Mark-IV Performance Summary; Rod or Disk? Center or Real FOV?; and Project Cost and Schedule.

ARPA/NRL X-Ray Laser Program - Semiannual Technical Report to Defense Advanced Research Projects Agency, 1 Jul 1974-31 December 1974

DTIC Science & Technology

1975-05-01

Finally, diagnostics for quantitative measurements of all these properties are necessary for meaningful comparison of the experiments with theoretical ...width (FWHM) of 120 ^rad. For comparison, a beam which fills the last amplifier rod has a corresponding theoretical divergence angle of 108 urad...hydrogen the protons produced by photoionization do not absorb). Also shown are the spontaneous lifetimes tu of the upper laser level, of use for self

Models for the Configuration and Integrity of Partially Oxidized Fuel Rod Cladding at High Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siefken, L.J.

1999-01-01

Models were designed to resolve deficiencies in the SCDAP/RELAP5/MOD3.2 calculations of the configuration and integrity of hot, partially oxidized cladding. These models are expected to improve the calculations of several important aspects of fuel rod behavior. First, an improved mapping was established from a compilation of PIE results from severe fuel damage tests of the configuration of melted metallic cladding that is retained by an oxide layer. The improved mapping accounts for the relocation of melted cladding in the circumferential direction. Then, rules based on PIE results were established for calculating the effect of cladding that has relocated from abovemore » on the oxidation and integrity of the lower intact cladding upon which it solidifies. Next, three different methods were identified for calculating the extent of dissolution of the oxidic part of the cladding due to its contact with the metallic part. The extent of dissolution effects the stress and thus the integrity of the oxidic part of the cladding. Then, an empirical equation was presented for calculating the stress in the oxidic part of the cladding and evaluating its integrity based on this calculated stress. This empirical equation replaces the current criterion for loss of integrity which is based on temperature and extent of oxidation. Finally, a new rule based on theoretical and experimental results was established for identifying the regions of a fuel rod with oxidation of both the inside and outside surfaces of the cladding. The implementation of these models is expected to eliminate the tendency of the SCDAP/RELAP5 code to overpredict the extent of oxidation of the upper part of fuel rods and to underpredict the extent of oxidation of the lower part of fuel rods and the part with a high concentration of relocated material. This report is a revision and reissue of the report entitled, Improvements in Modeling of Cladding Oxidation and Meltdown.« less

Transient release kinetics of rod bipolar cells revealed by capacitance measurement of exocytosis from axon terminals in rat retinal slices.

PubMed

Oltedal, Leif; Hartveit, Espen

2010-05-01

Presynaptic transmitter release has mostly been studied through measurements of postsynaptic responses, but a few synapses offer direct access to the presynaptic terminal, thereby allowing capacitance measurements of exocytosis. For mammalian rod bipolar cells, synaptic transmission has been investigated in great detail by recording postsynaptic currents in AII amacrine cells. Presynaptic measurements of the dynamics of vesicular cycling have so far been limited to isolated rod bipolar cells in dissociated preparations. Here, we first used computer simulations of compartmental models of morphologically reconstructed rod bipolar cells to adapt the 'Sine + DC' technique for capacitance measurements of exocytosis at axon terminals of intact rod bipolar cells in retinal slices. In subsequent physiological recordings, voltage pulses that triggered presynaptic Ca(2+) influx evoked capacitance increases that were proportional to the pulse duration. With pulse durations 100 ms, the increase saturated at 10 fF, corresponding to the size of a readily releasable pool of vesicles. Pulse durations 400 ms evoked additional capacitance increases, probably reflecting recruitment from additional pools of vesicles. By using Ca(2+) tail current stimuli, we separated Ca(2+) influx from Ca(2+) channel activation kinetics, allowing us to estimate the intrinsic release kinetics of the readily releasable pool, yielding a time constant of 1.1 ms and a maximum release rate of 2-3 vesicles (release site)(1) ms(1). Following exocytosis, we observed endocytosis with time constants ranging from 0.7 to 17 s. Under physiological conditions, it is likely that release will be transient, with the kinetics limited by the activation kinetics of the voltage-gated Ca(2+) channels.

Molecular evolutionary analysis of vertebrate transducins: a role for amino acid variation in photoreceptor deactivation.

PubMed

Lin, Yi G; Weadick, Cameron J; Santini, Francesco; Chang, Belinda S W

2013-12-01

Transducin is a heterotrimeric G protein that plays a critical role in phototransduction in the rod and cone photoreceptor cells of the vertebrate retina. Rods, highly sensitive cells that recover from photoactivation slowly, underlie dim-light vision, whereas cones are less sensitive, recover more quickly, and underlie bright-light vision. Transducin deactivation is a critical step in photoreceptor recovery and may underlie the functional distinction between rods and cones. Rods and cones possess distinct transducin α subunits, yet they share a common deactivation mechanism, the GTPase activating protein (GAP) complex. Here, we used codon models to examine patterns of sequence evolution in rod (GNAT1) and cone (GNAT2) α subunits. Our results indicate that purifying selection is the dominant force shaping GNAT1 and GNAT2 evolution, but that GNAT2 has additionally been subject to positive selection operating at multiple phylogenetic scales; phylogeny-wide analysis identified several sites in the GNAT2 helical domain as having substantially elevated dN/dS estimates, and branch-site analysis identified several nearby sites as targets of strong positive selection during early vertebrate history. Examination of aligned GNAT and GAP complex crystal structures revealed steric clashes between several positively selected sites and the deactivating GAP complex. This suggests that GNAT2 sequence variation could play an important role in adaptive evolution of the vertebrate visual system via effects on photoreceptor deactivation kinetics and provides an alternative perspective to previous work that focused instead on the effect of GAP complex concentration. Our findings thus further the understanding of the molecular biology, physiology, and evolution of vertebrate visual systems.

Purinergic modulation of frog electroretinographic responses: The role of the ionotropic receptor P2X7.

PubMed

Kupenova, Petia; Popova, Elka; Vitanova, Liliya

2017-01-01

The contribution of the purinergic receptors P2X7 (P2X7Rs) to the electroretinographic (ERG) responses was studied by testing the effects of the selective P2X7R antagonist A438079 and the selective P2X7R agonist Bz-ATP on the electroretinograms obtained in perfused frog (Rana ridibunda) eyecup preparations under a variety of stimulation conditions. The P2X7R blockade by 200 µM A438079 diminished the amplitude of the photoreceptor components: the a-wave and the pharmacologically isolated mass receptor potential. In the pure rod-driven and pure cone-driven responses, the amplitude of the postreceptoral ON (b-wave) and OFF (d-wave) components was also diminished. The OFF responses were affected to a greater extent compared to the ON responses. In the mixed rod- and cone-driven responses, obtained in the mesopic intensity range, the b-wave amplitude was increased, while the d-wave amplitude was decreased. The amplitude of the oscillatory potentials was diminished. The relative amplitude changes produced by the P2X7R blockade were greater in the dark-adapted compared to the light-adapted eyes. The application of 100 µM Bz-ATP produced small effects opposite to those of the antagonist, while a prolonged (>20 min) treatment with 1 mM Bz-ATP resulted in a significant amplitude reduction or even abolishment of b- and d-waves. Our results show that endogenous ATP through its P2X7Rs exerts significant, mostly potentiating effects on the ERG photoreceptor and postreceptoral responses. There is a clear ON/OFF asymmetry of the effects on the ERG postreceptoral responses favoring OFF responses: they are always strongly potentiated, while the ON responses are either less potentiated (in the rod-driven and most of the cone-driven responses) or even inhibited (in the mixed rod- and cone-driven responses). The overstimulation of P2X7Rs can produce acute pathological changes, that is, a decrease or abolishment of the ERG responses.

Adaptive Dynamic Programming for Discrete-Time Zero-Sum Games.

PubMed

Wei, Qinglai; Liu, Derong; Lin, Qiao; Song, Ruizhuo

2018-04-01

In this paper, a novel adaptive dynamic programming (ADP) algorithm, called "iterative zero-sum ADP algorithm," is developed to solve infinite-horizon discrete-time two-player zero-sum games of nonlinear systems. The present iterative zero-sum ADP algorithm permits arbitrary positive semidefinite functions to initialize the upper and lower iterations. A novel convergence analysis is developed to guarantee the upper and lower iterative value functions to converge to the upper and lower optimums, respectively. When the saddle-point equilibrium exists, it is emphasized that both the upper and lower iterative value functions are proved to converge to the optimal solution of the zero-sum game, where the existence criteria of the saddle-point equilibrium are not required. If the saddle-point equilibrium does not exist, the upper and lower optimal performance index functions are obtained, respectively, where the upper and lower performance index functions are proved to be not equivalent. Finally, simulation results and comparisons are shown to illustrate the performance of the present method.

Evolutionary Origin of OwlRep, a Megasatellite DNA Associated with Adaptation of Owl Monkeys to Nocturnal Lifestyle

PubMed Central

Nishihara, Hidenori; Stanyon, Roscoe; Kusumi, Junko; Hirai, Hirohisa

2018-01-01

Abstract Rod cells of many nocturnal mammals have a “non-standard” nuclear architecture, which is called the inverted nuclear architecture. Heterochromatin localizes to the central region of the nucleus. This leads to an efficient light transmission to the outer segments of photoreceptors. Rod cells of diurnal mammals have the conventional nuclear architecture. Owl monkeys (genus Aotus) are the only taxon of simian primates that has a nocturnal or cathemeral lifestyle, and this adaptation is widely thought to be secondary. Their rod cells were shown to exhibit an intermediate chromatin distribution: a spherical heterochromatin block was found in the central region of the nucleus although it was less complete than that of typical nocturnal mammals. We recently demonstrated that the primary DNA component of this heterochromatin block was OwlRep, a megasatellite DNA consisting of 187-bp-long repeat units. However, the origin of OwlRep was not known. Here we show that OwlRep was derived from HSAT6, a simple repeat sequence found in the centromere regions of human chromosomes. HSAT6 occurs widely in primates, suggesting that it was already present in the last common ancestor of extant primates. Notably, Strepsirrhini and Tarsiformes apparently carry a single HSAT6 copy, whereas many species of Simiiformes contain multiple copies. Comparison of nucleotide sequences of these copies revealed the entire process of the OwlRep formation. HSAT6, with or without flanking sequences, was segmentally duplicated in New World monkeys. Then, in the owl monkey linage after its divergence from other New World monkeys, a copy of HSAT6 was tandemly amplified, eventually forming a megasatellite DNA. PMID:29294004

Adaptive optics scanning ophthalmoscopy with annular pupils

PubMed Central

Sulai, Yusufu N.; Dubra, Alfredo

2012-01-01

Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections. PMID:22808435

Expanded Retinal Disease Spectrum Associated With Autosomal Recessive Mutations in GUCY2D.

PubMed

Stunkel, Maria L; Brodie, Scott E; Cideciyan, Artur V; Pfeifer, Wanda L; Kennedy, Elizabeth L; Stone, Edwin M; Jacobson, Samuel G; Drack, Arlene V

2018-06-01

GUCY2D has been associated with autosomal recessive Leber congenital amaurosis and autosomal dominant cone-rod dystrophy. This report expands the phenotype of autosomal recessive mutations to congenital night blindness, which may slowly progress to mild retinitis pigmentosa. Retrospective case series. Multicenter study of 5 patients (3 male, 2 female). All patients presented with night blindness since childhood. Age at referral was 9-45 years. Length of follow-up was 1-7 years. Best-corrected visual acuity at presentation ranged from 20/15 to 20/30 and at most recent visit averaged 20/25. No patient had nystagmus or high refractive error. ISCEV standard electroretinography revealed nondetectable dark-adapted dim flash responses and reduced amplitude but not electronegative dark-adapted bright flash responses with similar waveforms to the reduced-amplitude light-adapted single flash responses. The 30 Hz flicker responses were relatively preserved. Macular optical coherence tomography revealed normal lamination in 3 patients, with abnormalities in 2. Goldmann visual fields were normal at presentation in children but constricted in 1 adult. One child showed loss of midperipheral fields over time. Fundus appearance was normal in childhood; the adult had sparse bone spicule-like pigmentation. Full-field stimulus testing (FST) revealed markedly decreased retinal sensitivity to light. Dark adaptation demonstrated lack of rod-cone break. Two patients had tritanopia. All 5 had compound heterozygous mutations in GUCY2D. Three of the 5 patients harbor the Arg768Trp mutation reported in GUCY2D-associated Leber congenital amaurosis. Autosomal recessive GUCY2D mutations may cause congenital night blindness with normal acuity and refraction, and unique electroretinography. Progression to mild retinitis pigmentosa may occur. Copyright © 2018 Elsevier Inc. All rights reserved.

Adaptive optics scanning ophthalmoscopy with annular pupils.

PubMed

Sulai, Yusufu N; Dubra, Alfredo

2012-07-01

Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections.

Rigid fixation improves outcomes of spinal fusion for C1-C2 instability in children with skeletal dysplasias.

PubMed

Helenius, Ilkka; Crawford, Haemish; Sponseller, Paul D; Odent, Thierry; Bernstein, Robert M; Stans, Anthony A; Hedequist, Daniel; Phillips, Jonathan H

2015-02-04

Upper cervical instability is common in many skeletal dysplasias, and surgical treatment can be difficult because of small, fragile osseous elements. In this study of children with skeletal dysplasia and upper cervical instability, we compared fusion rates and complications between (1) patients treated with no instrumentation or with wiring techniques and (2) those who underwent rigid cervical spine instrumentation. We also sought to characterize the presentation and common parameters of upper cervical instability in this population. A multicenter study identified twenty-eight children with skeletal dysplasia who underwent surgery from 2000 through 2011 for C1-C2 instability and were followed for a minimum of two years. Fourteen children were treated with no instrumentation or with instrumentation with wires or cables (nonrigid-fixation group) and fourteen were treated with screws (or hooks) and rods (rigid-fixation group). All patients received autograft, and twenty (twelve in the nonrigid group and eight in the rigid group) were treated with a halo-body jacket. Fourteen children had C1-C2 fusion, and fourteen had occipitocervical fusion. Eleven (39%) underwent spinal cord decompression. The nonunion rate was significantly higher in the nonrigid-fixation group (six of fourteen) than in the rigid-fixation group (zero of fourteen; p = 0.0057). Complications, including nonunion, occurred in nine patients in the nonrigid group and one patient in the rigid group. However, two of the complications in the nonrigid-fixation group were vertebral artery bleeding episodes that actually occurred during an attempt at rigid fixation (the fixation was subsequently done with wiring). No new neurologic deficits were observed. Five of the seven children with a preoperative neurologic deficit showed at least partial recovery, with significant improvement in the Japanese Orthopaedic Association upper-extremity score (p = 0.047). The nonunion rate is relatively high after patients undergo spinal fusion for C1-C2 instability with nonrigid instrumentation, even if a halo-body jacket is applied. Rigid fixation with screws and rods improves fusion rates. Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.

Fabrication of Lower Section and Upper Forward Bulkhead Panels of the Multi-Bay Box and Panel Preparation

NASA Technical Reports Server (NTRS)

Velicki, Alexander; Linton, Kim; Hoffman, Krishna; Thrash, Patrick; Pickell, Robert; Turley, Robert

2015-01-01

NASA and the Boeing Co. have been working together under the Environmentally Responsible Aviation Project to develop stitched unitized structure for reduced weight, reduced fuel burn and reduced pollutants in the next generation of commercial aircraft. The structural concept being evaluated is PRSEUS (Pultruded Rod Stitched Efficient Unitized Structure). In the PRSEUS concept, dry carbon fabric, pultruded carbon rods, and foam are stitched together into large preforms. Then these preforms are infused with an epoxy resin into large panels in an out-of-autoclave process. These panels have stiffeners in the length-wise and width-wise directions but contain no fasteners because all stiffeners are stitched to the panel skin. This document contains a description of the fabrication of panels for use in the 30-foot-long Multi-Bay Box test article to be evaluated at NASA LaRC. The document also describes a panel which explores new PRSEUS concepts for applications beyond the Multi-Bay Box.

Enhancing the ABAQUS thermomechanics code to simulate multipellet steady and transient LWR fuel rod behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. L. Williamson

A powerful multidimensional fuels performance analysis capability, applicable to both steady and transient fuel behavior, is developed based on enhancements to the commercially available ABAQUS general-purpose thermomechanics code. Enhanced capabilities are described, including: UO2 temperature and burnup dependent thermal properties, solid and gaseous fission product swelling, fuel densification, fission gas release, cladding thermal and irradiation creep, cladding irradiation growth, gap heat transfer, and gap/plenum gas behavior during irradiation. This new capability is demonstrated using a 2D axisymmetric analysis of the upper section of a simplified multipellet fuel rod, during both steady and transient operation. Comparisons are made between discrete andmore » smeared-pellet simulations. Computational results demonstrate the importance of a multidimensional, multipellet, fully-coupled thermomechanical approach. Interestingly, many of the inherent deficiencies in existing fuel performance codes (e.g., 1D thermomechanics, loose thermomechanical coupling, separate steady and transient analysis, cumbersome pre- and post-processing) are, in fact, ABAQUS strengths.« less

Evidence of incomplete annealing at 800 °C and the effects of 120 °C baking on the crystal orientation and the surface superconducting properties of cold-worked and chemically polished Nb

DOE PAGES

Sung, Z. -H.; Dzyuba, A.; Lee, P. J.; ...

2015-07-01

High-purity niobium rods were cold-worked by wire-drawing, followed by various combinations of chemical polishing and high-vacuum baking at 120 °C or annealing at 800 °C in order to better understand changes to the surface superconducting properties resulting from typical superconducting radio-frequency cavity processing. AC susceptibility measurements revealed an enhanced upper transition T c at ~ 9.3–9.4 K in all samples that was stable through all annealing steps, a value significantly above the accepted T c of 9.23 K for pure annealed niobium. Corresponding elevations were seen in the critical fields, the ratio of the surface critical field H c3 tomore » the bulk upper critical field H c2 rising to 2.3, well above the Ginzburg–Landau value of 1.695. Orientation imaging revealed an extensive dislocation rich sub-grain structure in the as-drawn rods, a small reduction of the surface strain after baking at 120 °C, and a substantial but incomplete recrystallization near the surface after annealing at 800 °C. We interpret these changes in surface superconducting and structural properties to extensive changes in the near-surface interstitial contamination produced by baking and annealing and to synergistic interactions between H and surface O introduced during electropolishing and buffered chemical polishing.« less

Evidence of incomplete annealing at 800 °C and the effects of 120 °C baking on the crystal orientation and the surface superconducting properties of cold-worked and chemically polished Nb

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sung, Z. -H.; Dzyuba, A.; Lee, P. J.

High-purity niobium rods were cold-worked by wire-drawing, followed by various combinations of chemical polishing and high-vacuum baking at 120 °C or annealing at 800 °C in order to better understand changes to the surface superconducting properties resulting from typical superconducting radio-frequency cavity processing. AC susceptibility measurements revealed an enhanced upper transition T c at ~ 9.3–9.4 K in all samples that was stable through all annealing steps, a value significantly above the accepted T c of 9.23 K for pure annealed niobium. Corresponding elevations were seen in the critical fields, the ratio of the surface critical field H c3 tomore » the bulk upper critical field H c2 rising to 2.3, well above the Ginzburg–Landau value of 1.695. Orientation imaging revealed an extensive dislocation rich sub-grain structure in the as-drawn rods, a small reduction of the surface strain after baking at 120 °C, and a substantial but incomplete recrystallization near the surface after annealing at 800 °C. We interpret these changes in surface superconducting and structural properties to extensive changes in the near-surface interstitial contamination produced by baking and annealing and to synergistic interactions between H and surface O introduced during electropolishing and buffered chemical polishing.« less

Nuclear reactor

DOEpatents

Yant, Howard W.; Stinebiser, Karl W.; Anzur, Gregory C.

1977-01-01

A nuclear reactor, particularly a liquid-metal breeder reactor, whose upper internals include outlet modules for channeling the liquid-metal coolant from selected areas of the outlet of the core vertically to the outlet plenum. The modules are composed of a highly-refractory, high corrosion-resistant alloy, for example, INCONEL-718. Each module is disposed to confine and channel generally vertically the coolant emitted from a subplurality of core-component assemblies. Each module has a grid with openings, each opening disposed to receive the coolant from an assembly of the subplurality. The grid in addition serves as a holdown for the assemblies of the corresponding subplurality preventing their excessive ejection upwardly from the core. In the region directly over the core the outlet modules are of such peripheral form that they nest forming a continuum over the core-component assemblies whose outlet coolant they confine. Each subassembly includes a chimney which confines the coolant emitted by its corresponding subassemblies to generally vertical flow between the outlet of the core and the outlet plenum. Each subplurality of assemblies whose emitted coolant is confined by an outlet module includes assemblies which emit lower-temperature coolant, for example, a control-rod assembly, or fertile assemblies, and assemblies which emit coolant of substantially higher temperature, for example, fuel-rod assemblies. The coolants of different temperatures are mixed in the chimneys reducing the effect of stripping (hot-cold temperature fluctuations) on the remainder of the upper internals which are composed typically of AISI-304 or AISI-316 stainless steel.

General view of the Space Shuttle Main Engine (SSME) assembly ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

General view of the Space Shuttle Main Engine (SSME) assembly with the expansion nozzle removed and resting on a cushioned mat on the floor of the SSME Processing Facility. The most prominent features in this view are the Low-pressure oxidizer Turbopump discharge Duct looping from the upper left side of the engine assembly to the lower left side of the assembly, the Low-Pressure Fuel Turbopump (LPFTP) is on the upper left of the assembly in this view and the LPFTP Discharge Duct loops from the upper left to upper right then turns back and down the assembly to the High-Pressure Fuel Turbopump on the lower right of the assembly. The Engine Controller and the Main fuel Valve Hydraulic Actuator are on the lower left portion of the assembly. The vertical rod that is in the approximate center of the engine assembly is a piece of ground support equipment call a Gimbal Actuator Replacement Strut which are used on the SSMEs when they are not installed in an orbiter. - Space Transportation System, Space Shuttle Main Engine, Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Mesopic luminance assessed with minimally distinct border perception

PubMed Central

Raphael, Sabine; MacLeod, Donald I. A.

2015-01-01

In photopic vision, the border between two fields is minimally distinct when the two fields are isoluminant; that is, when the achromatic luminance of the two fields is equal. The distinctness of a border between extrafoveal reference and comparison fields was used here as an isoluminance criterion under a variety of adaptation conditions ranging from photopic to scotopic. The adjustment was done by trading off the amount of blue against the amount of red in the comparison field. Results show that isoluminant border settings are linear under all constant adaptation conditions, though varying with state of adaptation. The relative contribution of rods and cones to luminance was modeled such that the linear sum of the suitably weighted scotopic and photopic luminance is constant for the mesopic isoluminant conditions. The relative weights change with adapting intensity in a sigmoid fashion and also depend strongly on the position of the border in the visual field. PMID:26223024

Guanylate cyclase-activating protein 2 contributes to phototransduction and light adaptation in mouse cone photoreceptors.

PubMed

Vinberg, Frans; Peshenko, Igor V; Chen, Jeannie; Dizhoor, Alexander M; Kefalov, Vladimir J

2018-05-11

Light adaptation of photoreceptor cells is mediated by Ca 2+ -dependent mechanisms. In darkness, Ca 2+ influx through cGMP-gated channels into the outer segment of photoreceptors is balanced by Ca 2+ extrusion via Na + /Ca 2+ , K + exchangers (NCKXs). Light activates a G protein signaling cascade, which closes cGMP-gated channels and decreases Ca 2+ levels in photoreceptor outer segment because of continuing Ca 2+ extrusion by NCKXs. Guanylate cyclase-activating proteins (GCAPs) then up-regulate cGMP synthesis by activating retinal membrane guanylate cyclases (RetGCs) in low Ca 2+ This activation of RetGC accelerates photoresponse recovery and critically contributes to light adaptation of the nighttime rod and daytime cone photoreceptors. In mouse rod photoreceptors, GCAP1 and GCAP2 both contribute to the Ca 2+ -feedback mechanism. In contrast, only GCAP1 appears to modulate RetGC activity in mouse cones because evidence of GCAP2 expression in cones is lacking. Surprisingly, we found that GCAP2 is expressed in cones and can regulate light sensitivity and response kinetics as well as light adaptation of GCAP1-deficient mouse cones. Furthermore, we show that GCAP2 promotes cGMP synthesis and cGMP-gated channel opening in mouse cones exposed to low Ca 2+ Our biochemical model and experiments indicate that GCAP2 significantly contributes to the activation of RetGC1 at low Ca 2+ when GCAP1 is not present. Of note, in WT mouse cones, GCAP1 dominates the regulation of cGMP synthesis. We conclude that, under normal physiological conditions, GCAP1 dominates the regulation of cGMP synthesis in mouse cones, but if its function becomes compromised, GCAP2 contributes to the regulation of phototransduction and light adaptation of cones. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Photoreceptor Layer Thickness Changes During Dark Adaptation Observed With Ultrahigh-Resolution Optical Coherence Tomography

PubMed Central

Lu, Chen D.; Lee, ByungKun; Schottenhamml, Julia; Maier, Andreas; Pugh, Edward N.; Fujimoto, James G.

2017-01-01

Purpose To examine outer retinal band changes after flash stimulus and subsequent dark adaptation with ultrahigh-resolution optical coherence tomography (UHR-OCT). Methods Five dark-adapted left eyes of five normal subjects were imaged with 3-μm axial-resolution UHR-OCT during 30 minutes of dark adaptation following 96%, 54%, 23%, and 0% full-field and 54% half-field rhodopsin bleach. We identified the ellipsoid zone inner segment/outer segment (EZ[IS/OS]), cone interdigitation zone (CIZ), rod interdigitation zone (RIZ), retinal pigment epithelium (RPE), and Bruch's membrane (BM) axial positions and generated two-dimensional thickness maps of the EZ(IS/OS) to the four bands. The average thickness over an area of the thickness map was compared against that of the dark-adapted baselines. The time-dependent thickness changes (photoresponses) were statistically compared against 0% bleach. Dark adaptometry was performed with the same bleaching protocol. Results The EZ(IS/OS)-CIZ photoresponse was significantly different at 96% (P < 0.0001) and 54% (P = 0.006) bleach. At all three bleaching levels, the EZ(IS/OS)-RIZ, -RPE, and -BM responses were significantly different (P < 0.0001). The EZ(IS/OS)-CIZ and EZ(IS/OS)-RIZ time courses were similar to the recovery of rod- and cone-mediated sensitivity, respectively, measured with dark adaptometry. The maximal EZ(IS/OS)-CIZ and EZ(IS/OS)-RIZ response magnitudes doubled from 54% to 96% bleach. Both EZ(IS/OS)-RPE and EZ(IS/OS)-BM responses resembled dampened oscillations that were graded in amplitude and duration with bleaching intensity. Half-field photoresponses were localized to the stimulated retina. Conclusions With noninvasive, near-infrared UHR-OCT, we characterized three distinct, spatially localized photoresponses in the outer retinal bands. These photoresponses have potential value as physical correlates of photoreceptor function. PMID:28898357

Lunar preform manufacturing

NASA Technical Reports Server (NTRS)

Leong, Gregory N.; Nease, Sandra; Lager, Vicky; Yaghjian, Raffy; Waller, Chris; Dorrity, J. Lewis

1992-01-01

A design for a machine to produce hollow, continuous fiber reinforced composite rods of lunar glass and a liquid crystalline matrix using the pultrusion process is presented. The glass fiber will be produced from the lunar surface, with the machine and matrix being transported to the moon. The process is adaptable to the low gravity and near-vacuum environment of the moon through the use of a thermoplastic matrix in fiber form as it enters the pultrusion process. With a power consumption of 5k W, the proposed machine will run continuously, unmanned in fourteen day cycles, matching the length of moon days. A number of dies could be included that would allow the machine to produce rods of varying diameter, I-beams, angles, and other structural members. These members could then be used for construction on the lunar surface or transported for use in orbit. The benefits of this proposal are in the savings in weight of the cargo each lunar mission would carry. The supply of glass on the moon is effectively endless, so enough rods would have to be produced to justify its transportation, operation, and capital cost. This should not be difficult as weight on lunar mission is at a premium.

Lunar preform manufacturing

NASA Technical Reports Server (NTRS)

Leong, Gregory N.; Nease, Sandra; Lager, Vicky; Yaghjian, Raffy; Waller, Chris

1992-01-01

A design for a machine to produce hollow, continuous fiber-reinforced composite rods of lunar glass and a liquid crystalline matrix using the pultrusion process is presented. The glass fiber will be produced from the lunar surface, with the machine and matrix being transported to the moon. The process is adaptable to the low gravity and near-vacuum environment of the moon through the use of a thermoplastic matrix in fiber form as it enters the pultrusion process. With a power consumption of 5 kW, the proposed machine will run unmanned continuously in fourteen-day cycles, matching the length of lunar days. A number of dies could be included that would allow the machine to produce rods of varying diameter, I-beams, angles, and other structural members. These members could then be used for construction on the lunar surface or transported for use in orbit. The benefits of this proposal are in the savings in weight of the cargo each lunar mission would carry. The supply of glass on the moon is effectively endless, so enough rods would have to be produced to justify its transportation, operation, and capital cost. This should not be difficult as weight on lunar mission is at a premium.

The physiological roles of arrestin-1 in rod photoreceptor cells.

PubMed

Chen, Jeannie

2014-01-01

Arrestin-1 is the second most abundant protein in rod photoreceptors and is nearly equimolar to rhodopsin. Its well-recognized role is to "arrest" signaling from light-activated, phosphorylated rhodopsin, a prototypical G protein-coupled receptor. In doing so, arrestin-1 plays a key role in the rapid recovery of the light response. Arrestin-1 exists in a basal conformation that is stabilized by two independent sets of intramolecular interactions. The intramolecular constraints are disrupted by encountering (1) active conformation of the receptor (R*) and (2) receptor-attached phosphates. Requirement for these two events ensures its highly specific high-affinity binding to phosphorylated, light-activated rhodopsin (P-R*). In the dark-adapted state, the basal form is further organized into dimers and tetramers. Emerging data suggest pleiotropic roles of arrestin-1 beyond the functional range of rod cells. These include light-induced arrestin-1 translocation from the inner segment to the outer segment, a process that may be protective against cellular damage incurred by constitutive signaling. Its expanding list of binding partners also hints at additional, yet to be characterized functions. Uncovering these novel roles of arrestin-1 is a subject of future studies.

The Virtual Climate Data Server (vCDS): An iRODS-Based Data Management Software Appliance Supporting Climate Data Services and Virtualization-as-a-Service in the NASA Center for Climate Simulation

NASA Technical Reports Server (NTRS)

Schnase, John L.; Tamkin, Glenn S.; Ripley, W. David III; Stong, Savannah; Gill, Roger; Duffy, Daniel Q.

2012-01-01

Scientific data services are becoming an important part of the NASA Center for Climate Simulation's mission. Our technological response to this expanding role is built around the concept of a Virtual Climate Data Server (vCDS), repetitive provisioning, image-based deployment and distribution, and virtualization-as-a-service. The vCDS is an iRODS-based data server specialized to the needs of a particular data-centric application. We use RPM scripts to build vCDS images in our local computing environment, our local Virtual Machine Environment, NASA s Nebula Cloud Services, and Amazon's Elastic Compute Cloud. Once provisioned into one or more of these virtualized resource classes, vCDSs can use iRODS s federation capabilities to create an integrated ecosystem of managed collections that is scalable and adaptable to changing resource requirements. This approach enables platform- or software-asa- service deployment of vCDS and allows the NCCS to offer virtualization-as-a-service: a capacity to respond in an agile way to new customer requests for data services.

pH and rate of ‘dark’ events in toad retinal rods: test of a hypothesis on the molecular origin of photoreceptor noise

PubMed Central

Firsov, Mikhail L; Donner, Kristian; Govardovskii, Victor I

2002-01-01

Thermal activation of the visual pigment constitutes a fundamental constraint on visual sensitivity. Its electrical correlate in the membrane current of dark-adapted rods are randomly occurring discrete ‘dark events’ indistinguishable from responses to single photons. It has been proposed that thermal activation occurs in a small subpopulation of rhodopsin molecules where the Schiff base linking the chromophore to the protein part is unprotonated. On this hypothesis, rates of thermal activation should increase strongly with rising pH. The hypothesis has been tested by measuring the effect of pH changes on the frequency of discrete dark events in red rods of the common toad Bufo bufo. Dark noise was recorded from isolated rods using the suction pipette technique. Changes in cytoplasmic pH upon manipulations of extracellular pH were quantified by measuring, using fast single-cell microspectrophotometry, the pH-dependent metarhodopsin I-metarhodopsin II equilibrium and subsequent metarhodopsin III formation. These measurements show that, in the conditions of the electrophysiological experiments, changing perfusion pH from 6.5 to 9.3 resulted in a cytoplasmic pH shift from 7.6 to 8.5 that was readily sensed by the rhodopsin. This shift, which implies an 8-fold decrease in cytoplasmic [H+], did not increase the rate of dark events. The results contradict the hypothesis that thermal pigment activation depends on prior deprotonation of the Schiff base. PMID:11897853

Wireline tool cable head overload apparatus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roessler, D.E.

1990-05-29

This patent describes a cable head adapted to support a sonde in a well borehole. It comprises: an upper end assembly adapted for connection with a cable extending into a well borehole; a lower end assembly adapted for connection to a sonde to be supported by the cable in the well borehole; yieldable means joining the upper and lower assemblies together in a fixed but yieldable relationship wherein a controllable and variable load is imparted to the cable there above during movement and variations in load on the cable are maintained within specified limits; the yieldable means further including deadmore » weight adjustable means notwithstanding variations in the dead weight of the load, and the yieldable means includes resilient means permitting movements within a desired range dependent on the adjustment thereof and bracketing a selected relative position of the upper and lower end assemblies; and an electrical contact.« less

TMI-2 (Three Mile Island Unit 2) core region defueling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodabaugh, J.M.; Cowser, D.K.

1988-01-01

In July of 1982, a video camera was inserted into the Three Mile Island Unit 2 reactor vessel providing the first visual evidence of core damage. This inspection, and numerous subsequent data acquisition tasks, revealed a central void /approx/1.5 m (5 ft) deep. This void region was surrounded by partial length fuel assemblies and ringed on the periphery by /approx/40 full-length, but partial cross-section, fuel assemblies. All of the original 177 fuel assemblies exhibited signs of damage. The bottom of the void cavity was covered with a bed of granular rubble, fuel assembly upper end fittings, control rod spiders, fuelmore » rod fragments, and fuel pellets. It was obvious that the normal plant refueling system not suitable for removing the damaged core. A new system of defueling tools and equipment was necessary to perform this task. Design of the new system was started immediately, followed by >1 yr of fabrication. Delivery and checkout of the defueling system occurred in mid-1985. Actual defueling was initiated in late 1985 with removal of the debris bed at the bottom of the core void. Obstructions to the debris, such as end fittings and fuel rod fragments ere removed first; then /approx/23,000 kg (50,000lb) of granular debris was quickly loaded into canisters. Core region defueling was completed in late 1987, /approx/2 yr after it was initiated.« less

50. VIEW OF CRUSHER ADDITION FROM EAST. SHOWS 100TON STEEL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

50. VIEW OF CRUSHER ADDITION FROM EAST. SHOWS 100-TON STEEL UNOXIDIZED ORE BIN, STEPHENS-ADAMSON 15 TON/HR INCLINED BUCKET ELEVATOR, AND DUST COLLECTION BIN IN UPPER RIGHT QUADRANT. THE ROD MILL CIRCUIT STOOD IN FRONT OF THE BUCKET ELEVATOR AND BEHIND THE BAKER COOLER (LEFT CENTER). MILL SOLUTION TANKS WERE IN FRONT OF THE CRUSHED OXIDIZED ORE BIN (CENTER), AND THE MILL FLOOR WAS THE NEXT LEVEL DOWN (RIGHT). - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

78 FR 7810 - Glen Canyon Dam Adaptive Management Work Group

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-04

.... Dated: January 29, 2013. Anamarie Gold, Deputy Regional Director, Upper Colorado Regional Office, Salt... Reclamation, Upper Colorado Regional Office, 125 South State Street, Room 6107, Salt Lake City, Utah, 84138...

Robotics, assistive technology, and occupational therapy management to improve upper limb function in pediatric neuromuscular diseases.

PubMed

Rahman, Tariq; Basante, Joseph; Alexander, Michael

2012-08-01

This article presents an overview of occupational therapy assessments and treatment options for individuals with neuromuscular disabilities, with a particular focus on children with neuromuscular disorders. The discussion includes descriptions of standard treatments, commercial adaptive equipment, and homemade adaptive solutions. The state of the art in therapeutic and assistive robots and orthoses for the upper and lower extremity is also provided. Copyright © 2012. Published by Elsevier Inc.

The photocurrent, noise and spectral sensitivity of rods of the monkey Macaca fascicularis.

PubMed Central

Baylor, D A; Nunn, B J; Schnapf, J L

1984-01-01

Visual transduction in rods of the cynomolgus monkey, Macaca fascicularis, was studied by recording membrane current from single outer segments projecting from small pieces of retina. Light flashes evoked transient outward-going photocurrents with saturating amplitudes of up to 34 pA. A flash causing twenty to fifty photoisomerizations gave a response of half the saturating amplitude. The response-stimulus relation was of the form 1-e-x where x is flash strength. The response to a dim flash usually had a time to peak of 150-250 ms and resembled the impulse response of a series of six low-pass filters. From the average spectral sensitivity of ten rods the rhodopsin was estimated to have a peak absorption near 491 nm. The spectral sensitivity of the rods was in good agreement with the average human scotopic visibility curve determined by Crawford (1949), when the human curve was corrected for lens absorption and self-screening of rhodopsin. Fluctuations in the photocurrent evoked by dim lights were consistent with a quantal event about 0.7 pA in peak amplitude. A steady light causing about 100 photoisomerizations s-1 reduced the flash sensitivity to half the dark-adapted value. At higher background levels the rod rapidly saturated. These results support the idea that dim background light desensitizes human scotopic vision by a mechanism central to the rod outer segments while scotopic saturation may occur within the outer segments. Recovery of the photocurrent after bright flashes was marked by quantized step-like events. The events had the properties expected if bleached rhodopsin in the disks occasionally caused an abrupt blockage of the dark current over about one-twentieth of the length of the outer segment. It is suggested that superposition of these events after bleaching may contribute to the threshold elevation measured psychophysically. The current in darkness showed random fluctuations which disappeared in bright light. The continuous component of the noise had a variance of about 0.03 pA2 and a power spectrum that fell to half near 3 Hz. A second component, consisting of discrete events resembling single-photon responses, was estimated to occur at a rate of 0.006 s-1. It is suggested that the continuous component of the noise may be removed from scotopic vision by a thresholding operation near the rod output. PMID:6512705

The photocurrent, noise and spectral sensitivity of rods of the monkey Macaca fascicularis.

PubMed

Baylor, D A; Nunn, B J; Schnapf, J L

1984-12-01

Visual transduction in rods of the cynomolgus monkey, Macaca fascicularis, was studied by recording membrane current from single outer segments projecting from small pieces of retina. Light flashes evoked transient outward-going photocurrents with saturating amplitudes of up to 34 pA. A flash causing twenty to fifty photoisomerizations gave a response of half the saturating amplitude. The response-stimulus relation was of the form 1-e-x where x is flash strength. The response to a dim flash usually had a time to peak of 150-250 ms and resembled the impulse response of a series of six low-pass filters. From the average spectral sensitivity of ten rods the rhodopsin was estimated to have a peak absorption near 491 nm. The spectral sensitivity of the rods was in good agreement with the average human scotopic visibility curve determined by Crawford (1949), when the human curve was corrected for lens absorption and self-screening of rhodopsin. Fluctuations in the photocurrent evoked by dim lights were consistent with a quantal event about 0.7 pA in peak amplitude. A steady light causing about 100 photoisomerizations s-1 reduced the flash sensitivity to half the dark-adapted value. At higher background levels the rod rapidly saturated. These results support the idea that dim background light desensitizes human scotopic vision by a mechanism central to the rod outer segments while scotopic saturation may occur within the outer segments. Recovery of the photocurrent after bright flashes was marked by quantized step-like events. The events had the properties expected if bleached rhodopsin in the disks occasionally caused an abrupt blockage of the dark current over about one-twentieth of the length of the outer segment. It is suggested that superposition of these events after bleaching may contribute to the threshold elevation measured psychophysically. The current in darkness showed random fluctuations which disappeared in bright light. The continuous component of the noise had a variance of about 0.03 pA2 and a power spectrum that fell to half near 3 Hz. A second component, consisting of discrete events resembling single-photon responses, was estimated to occur at a rate of 0.006 s-1. It is suggested that the continuous component of the noise may be removed from scotopic vision by a thresholding operation near the rod output.

Rod-cone interaction in light adaptation

PubMed Central

Latch, M.; Lennie, P.

1977-01-01

1. The increment-threshold for a small test spot in the peripheral visual field was measured against backgrounds that were red or blue. 2. When the background was a large uniform field, threshold over most of the scotopic range depended exactly upon the background's effect upon rods. This confirms Flamant & Stiles (1948). But when the background was small, threshold was elevated more by a long wave-length than a short wave-length background equated for its effect on rods. 3. The influence of cones was explored in a further experiment. The scotopic increment-threshold was established for a short wave-length test spot on a large, short wave-length background. Then a steady red circular patch, conspicuous to cones, but below the increment-threshold for rod vision, was added to the background. When it was small, but not when it was large, this patch substantially raised the threshold for the test. 4. When a similar experiment was made using, instead of a red patch, a short wave-length one that was conspicuous in rod vision, threshold varied similarly with patch size. These results support the notion that the influence of small backgrounds arises in some size-selective mechanism that is indifferent to the receptor system in which visual signals originate. Two corollaries of this hypothesis were tested in further experiments. 5. A small patch was chosen so as to lift scotopic threshold substantially above its level on a uniform field. This threshold elevation persisted for minutes after extinction of the patch, but only when the patch was small. A large patch made bright enough to elevate threshold by as much as the small one gave rise to no corresponding after-effect. 6. Increment-thresholds for a small red test spot, detected through cones, followed the same course whether a large uniform background was long- or short wave-length. When the background was small, threshold upon the short wave-length one began to rise for much lower levels of background illumination, suggesting the influence of rods. This was confirmed by repeating the experiment after a strong bleach when the cones, but not rods, had fully recovered their sensitivity. Increment-thresholds upon small backgrounds of long or short wave-lengths then followed the same course. PMID:894602

Unilateral retinitis pigmentosa sine pigmento.

PubMed Central

Pearlman, J T; Saxton, J; Hoffman, G

1976-01-01

A patient presented with unilateral findings of night blindness shown by impaired rod function and dark adaptation, constricted visual fields with good central acuity, a barely recordable electro-retinographic b-wave, and a unilaterally impaired electro-oculogram. There were none of the pigmentary changes usually associated with retinitis pigmentosa. The unaffected right eye was normal in all respects. Therefore the case is most probably one of unilateral retinitis pigmentosa sine pigmento. Images PMID:952804

Unilateral retinitis pigmentosa sine pigmento.

PubMed

Pearlman, J T; Saxton, J; Hoffman, G

1976-05-01

A patient presented with unilateral findings of night blindness shown by impaired rod function and dark adaptation, constricted visual fields with good central acuity, a barely recordable electro-retinographic b-wave, and a unilaterally impaired electro-oculogram. There were none of the pigmentary changes usually associated with retinitis pigmentosa. The unaffected right eye was normal in all respects. Therefore the case is most probably one of unilateral retinitis pigmentosa sine pigmento.

A CTRP5 gene S163R mutation knock-in mouse model for late-onset retinal degeneration.

PubMed

Chavali, Venkata R M; Khan, Naheed W; Cukras, Catherine A; Bartsch, Dirk-Uwe; Jablonski, Monica M; Ayyagari, Radha

2011-05-15

Late-onset retinal macular degeneration (L-ORD) is an autosomal dominant inherited disorder caused by a single missense mutation (S163R) in the CTRP5/C1QTNF5 protein. Early phenotypic features of L-ORD include: dark adaptation abnormalities, nyctalopia, and drusen deposits in the peripheral macular region. Apart from posterior segment abnormalities, these patients also develop abnormally long anterior lens zonules. In the sixth decade of life the rod and cone function declines, accompanied by electroretinogram (ERG) abnormalities. Some patients also develop choroidal neovascularization and glaucoma. In order to understand the disease pathology and mechanisms involved in retinal dystrophy, we generated a knock-in (Ctrp5(+/-)) mouse model carrying the disease-associated mutation in the mouse Ctrp5/C1QTNF5 gene. These mice develop slower rod-b wave recovery consistent with early dark adaptation abnormalities, accumulation of hyperautofluorescence spots, retinal pigment epithelium abnormalities, drusen, Bruch's membrane abnormalities, loss of photoreceptors, and retinal vascular leakage. The Ctrp5(+/-) mice, which have most of the pathological features of age-related macular degeneration, are unique and may serve as a valuable model both to understand the molecular pathology of late-onset retinal degeneration and to evaluate therapies.

A CTRP5 gene S163R mutation knock-in mouse model for late-onset retinal degeneration

PubMed Central

Chavali, Venkata R.M.; Khan, Naheed W.; Cukras, Catherine A.; Bartsch, Dirk-Uwe; Jablonski, Monica M.; Ayyagari, Radha

2011-01-01

Late-onset retinal macular degeneration (L-ORD) is an autosomal dominant inherited disorder caused by a single missense mutation (S163R) in the CTRP5/C1QTNF5 protein. Early phenotypic features of L-ORD include: dark adaptation abnormalities, nyctalopia, and drusen deposits in the peripheral macular region. Apart from posterior segment abnormalities, these patients also develop abnormally long anterior lens zonules. In the sixth decade of life the rod and cone function declines, accompanied by electroretinogram (ERG) abnormalities. Some patients also develop choroidal neovascularization and glaucoma. In order to understand the disease pathology and mechanisms involved in retinal dystrophy, we generated a knock-in (Ctrp5+/−) mouse model carrying the disease-associated mutation in the mouse Ctrp5/C1QTNF5 gene. These mice develop slower rod-b wave recovery consistent with early dark adaptation abnormalities, accumulation of hyperautofluorescence spots, retinal pigment epithelium abnormalities, drusen, Bruch's membrane abnormalities, loss of photoreceptors, and retinal vascular leakage. The Ctrp5+/−mice, which have most of the pathological features of age-related macular degeneration, are unique and may serve as a valuable model both to understand the molecular pathology of late-onset retinal degeneration and to evaluate therapies. PMID:21349921

Volumetric imaging of rod and cone photoreceptor structure with a combined adaptive optics-optical coherence tomography-scanning laser ophthalmoscope

NASA Astrophysics Data System (ADS)

Wells-Gray, Elaine M.; Choi, Stacey S.; Zawadzki, Robert J.; Finn, Susanna C.; Greiner, Cherry; Werner, John S.; Doble, Nathan

2018-03-01

We have designed and implemented a dual-mode adaptive optics (AO) imaging system that combines spectral domain optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) for in vivo imaging of the human retina. The system simultaneously acquires SLO frames and OCT B-scans at 60 Hz with an OCT volume acquisition time of 4.2 s. Transverse eye motion measured from the SLO is used to register the OCT B-scans to generate three-dimensional (3-D) volumes. Key optical design considerations include: minimizing system aberrations through the use of off-axis relay telescopes, conjugate pupil plane requirements, and the use of dichroic beam splitters to separate and recombine the OCT and SLO beams around the nonshared horizontal scanning mirrors. To demonstrate system performance, AO-OCT-SLO images and measurements are taken from three normal human subjects ranging in retinal eccentricity from the fovea out to 15-deg temporal and 20-deg superior. Also presented are en face OCT projections generated from the registered 3-D volumes. The ability to acquire high-resolution 3-D images of the human retina in the midperiphery and beyond has clinical importance in diseases, such as retinitis pigmentosa and cone-rod dystrophy.

The absolute threshold of cone vision

PubMed Central

Koeing, Darran; Hofer, Heidi

2013-01-01

We report measurements of the absolute threshold of cone vision, which has been previously underestimated due to sub-optimal conditions or overly strict subjective response criteria. We avoided these limitations by using optimized stimuli and experimental conditions while having subjects respond within a rating scale framework. Small (1′ fwhm), brief (34 msec), monochromatic (550 nm) stimuli were foveally presented at multiple intensities in dark-adapted retina for 5 subjects. For comparison, 4 subjects underwent similar testing with rod-optimized stimuli. Cone absolute threshold, that is, the minimum light energy for which subjects were just able to detect a visual stimulus with any response criterion, was 203 ± 38 photons at the cornea, ∼0.47 log units lower than previously reported. Two-alternative forced-choice measurements in a subset of subjects yielded consistent results. Cone thresholds were less responsive to criterion changes than rod thresholds, suggesting a limit to the stimulus information recoverable from the cone mosaic in addition to the limit imposed by Poisson noise. Results were consistent with expectations for detection in the face of stimulus uncertainty. We discuss implications of these findings for modeling the first stages of human cone vision and interpreting psychophysical data acquired with adaptive optics at the spatial scale of the receptor mosaic. PMID:21270115

Adaptive control of 5 DOF upper-limb exoskeleton robot with improved safety.

PubMed

Kang, Hao-Bo; Wang, Jian-Hui

2013-11-01

This paper studies an adaptive control strategy for a class of 5 DOF upper-limb exoskeleton robot with a special safety consideration. The safety requirement plays a critical role in the clinical treatment when assisting patients with shoulder, elbow and wrist joint movements. With the objective of assuring the tracking performance of the pre-specified operations, the proposed adaptive controller is firstly designed to be robust to the model uncertainties. To further improve the safety and fault-tolerance in the presence of unknown large parameter variances or even actuator faults, the adaptive controller is on-line updated according to the information provided by an adaptive observer without additional sensors. An output tracking performance is well achieved with a tunable error bound. The experimental example also verifies the effectiveness of the proposed control scheme. © 2013 ISA. Published by ISA. All rights reserved.

Adaptive nonsingular fast terminal sliding-mode control for the tracking problem of uncertain dynamical systems.

PubMed

Boukattaya, Mohamed; Mezghani, Neila; Damak, Tarak

2018-06-01

In this paper, robust and adaptive nonsingular fast terminal sliding-mode (NFTSM) control schemes for the trajectory tracking problem are proposed with known or unknown upper bound of the system uncertainty and external disturbances. The developed controllers take the advantage of the NFTSM theory to ensure fast convergence rate, singularity avoidance, and robustness against uncertainties and external disturbances. First, a robust NFTSM controller is proposed which guarantees that sliding surface and equilibrium point can be reached in a short finite-time from any initial state. Then, in order to cope with the unknown upper bound of the system uncertainty which may be occurring in practical applications, a new adaptive NFTSM algorithm is developed. One feature of the proposed control law is their adaptation techniques where the prior knowledge of parameters uncertainty and disturbances is not needed. However, the adaptive tuning law can estimate the upper bound of these uncertainties using only position and velocity measurements. Moreover, the proposed controller eliminates the chattering effect without losing the robustness property and the precision. Stability analysis is performed using the Lyapunov stability theory, and simulation studies are conducted to verify the effectiveness of the developed control schemes. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Oriented clonal cell dynamics enables accurate growth and shaping of vertebrate cartilage

PubMed Central

Kaucka, Marketa; Zikmund, Tomas; Tesarova, Marketa; Gyllborg, Daniel; Hellander, Andreas; Jaros, Josef; Kaiser, Jozef; Petersen, Julian; Szarowska, Bara; Newton, Phillip T; Dyachuk, Vyacheslav; Li, Lei; Qian, Hong; Johansson, Anne-Sofie; Mishina, Yuji; Currie, Joshua D; Tanaka, Elly M; Erickson, Alek; Dudley, Andrew; Brismar, Hjalmar; Southam, Paul; Coen, Enrico; Chen, Min; Weinstein, Lee S; Hampl, Ales; Arenas, Ernest; Chagin, Andrei S; Fried, Kaj; Adameyko, Igor

2017-01-01

Cartilaginous structures are at the core of embryo growth and shaping before the bone forms. Here we report a novel principle of vertebrate cartilage growth that is based on introducing transversally-oriented clones into pre-existing cartilage. This mechanism of growth uncouples the lateral expansion of curved cartilaginous sheets from the control of cartilage thickness, a process which might be the evolutionary mechanism underlying adaptations of facial shape. In rod-shaped cartilage structures (Meckel, ribs and skeletal elements in developing limbs), the transverse integration of clonal columns determines the well-defined diameter and resulting rod-like morphology. We were able to alter cartilage shape by experimentally manipulating clonal geometries. Using in silico modeling, we discovered that anisotropic proliferation might explain cartilage bending and groove formation at the macro-scale. DOI: http://dx.doi.org/10.7554/eLife.25902.001 PMID:28414273

Piezoelectric step-motion actuator

DOEpatents

Mentesana,; Charles, P [Leawood, KS

2006-10-10

A step-motion actuator using piezoelectric material to launch a flight mass which, in turn, actuates a drive pawl to progressively engage and drive a toothed wheel or rod to accomplish stepped motion. Thus, the piezoelectric material converts electrical energy into kinetic energy of the mass, and the drive pawl and toothed wheel or rod convert the kinetic energy of the mass into the desired rotary or linear stepped motion. A compression frame may be secured about the piezoelectric element and adapted to pre-compress the piezoelectric material so as to reduce tensile loads thereon. A return spring may be used to return the mass to its resting position against the compression frame or piezoelectric material following launch. Alternative embodiment are possible, including an alternative first embodiment wherein two masses are launched in substantially different directions, and an alternative second embodiment wherein the mass is eliminated in favor of the piezoelectric material launching itself.

Content range and precision of a computer adaptive test of upper extremity function for children with cerebral palsy.

PubMed

Montpetit, Kathleen; Haley, Stephen; Bilodeau, Nathalie; Ni, Pengsheng; Tian, Feng; Gorton, George; Mulcahey, M J

2011-02-01

This article reports on the content range and measurement precision of an upper extremity (UE) computer adaptive testing (CAT) platform of physical function in children with cerebral palsy. Upper extremity items representing skills of all abilities were administered to 305 parents. These responses were compared with two traditional standardized measures: Pediatric Outcomes Data Collection Instrument and Functional Independence Measure for Children. The UE CAT correlated strongly with the upper extremity component of these measures and had greater precision when describing individual functional ability. The UE item bank has wider range with items populating the lower end of the ability spectrum. This new UE item bank and CAT have the capability to quickly assess children of all ages and abilities with good precision and, most importantly, with items that are meaningful and appropriate for their age and level of physical function.

Diversity and evolution of phycobilisomes in marine Synechococcus spp.: a comparative genomics study.

PubMed

Six, Christophe; Thomas, Jean-Claude; Garczarek, Laurence; Ostrowski, Martin; Dufresne, Alexis; Blot, Nicolas; Scanlan, David J; Partensky, Frédéric

2007-01-01

Marine Synechococcus owe their specific vivid color (ranging from blue-green to orange) to their large extrinsic antenna complexes called phycobilisomes, comprising a central allophycocyanin core and rods of variable phycobiliprotein composition. Three major pigment types can be defined depending on the major phycobiliprotein found in the rods (phycocyanin, phycoerythrin I or phycoerythrin II). Among strains containing both phycoerythrins I and II, four subtypes can be distinguished based on the ratio of the two chromophores bound to these phycobiliproteins. Genomes of eleven marine Synechococcus strains recently became available with one to four strains per pigment type or subtype, allowing an unprecedented comparative genomics study of genes involved in phycobilisome metabolism. By carefully comparing the Synechococcus genomes, we have retrieved candidate genes potentially required for the synthesis of phycobiliproteins in each pigment type. This includes linker polypeptides, phycobilin lyases and a number of novel genes of uncharacterized function. Interestingly, strains belonging to a given pigment type have similar phycobilisome gene complements and organization, independent of the core genome phylogeny (as assessed using concatenated ribosomal proteins). While phylogenetic trees based on concatenated allophycocyanin protein sequences are congruent with the latter, those based on phycocyanin and phycoerythrin notably differ and match the Synechococcus pigment types. We conclude that the phycobilisome core has likely evolved together with the core genome, while rods must have evolved independently, possibly by lateral transfer of phycobilisome rod genes or gene clusters between Synechococcus strains, either via viruses or by natural transformation, allowing rapid adaptation to a variety of light niches.

Transverse Diode Pumping of Solid-State Lasers

DTIC Science & Technology

1992-05-29

more common apertures (laser rod end and cavity end mirror ) leads to a thin-film coating damage issue. The transverse pumped geometry avoids the...proprietary one-half inch square cooler developed for high-power adaptive optics mirror applications. The laser performance observed, with up to 35 watts of...including the development of active mirrors capable of sustaining high power loadings. As part of those efforts, TTC has developed a small (one-half inch

Lipofuscin and N-Retinylidene-N-Retinylethanolamine (A2E) Accumulate in Retinal Pigment Epithelium in Absence of Light Exposure

PubMed Central

Boyer, Nicholas P.; Higbee, Daniel; Currin, Mark B.; Blakeley, Lorie R.; Chen, Chunhe; Ablonczy, Zsolt; Crouch, Rosalie K.; Koutalos, Yiannis

2012-01-01

The age-dependent accumulation of lipofuscin in the retinal pigment epithelium (RPE) has been associated with the development of retinal diseases, particularly age-related macular degeneration and Stargardt disease. A major component of lipofuscin is the bis-retinoid N-retinylidene-N-retinylethanolamine (A2E). The current model for the formation of A2E requires photoactivation of rhodopsin and subsequent release of all-trans-retinal. To understand the role of light exposure in the accumulation of lipofuscin and A2E, we analyzed RPEs and isolated rod photoreceptors from mice of different ages and strains, reared either in darkness or cyclic light. Lipofuscin levels were determined by fluorescence imaging, whereas A2E levels were quantified by HPLC and UV-visible absorption spectroscopy. The identity of A2E was confirmed by tandem mass spectrometry. Lipofuscin and A2E levels in the RPE increased with age and more so in the Stargardt model Abca4−/− than in the wild type strains 129/sv and C57Bl/6. For each strain, the levels of lipofuscin precursor fluorophores in dark-adapted rods and the levels and rates of increase of RPE lipofuscin and A2E were not different between dark-reared and cyclic light-reared animals. Both 11-cis- and all-trans-retinal generated lipofuscin-like fluorophores when added to metabolically compromised rod outer segments; however, it was only 11-cis-retinal that generated such fluorophores when added to metabolically intact rods. The results suggest that lipofuscin originates from the free 11-cis-retinal that is continuously supplied to the rod for rhodopsin regeneration and outer segment renewal. The physiological role of Abca4 may include the translocation of 11-cis-retinal complexes across the disk membrane. PMID:22570475

Progressive Reduction of its Expression in Rods Reveals Two Pools of Arrestin-1 in the Outer Segment with Different Roles in Photoresponse Recovery

PubMed Central

Cleghorn, Whitney M.; Tsakem, Elviche L.; Song, Xiufeng; Vishnivetskiy, Sergey A.; Seo, Jungwon; Chen, Jeannie; Gurevich, Eugenia V.; Gurevich, Vsevolod V.

2011-01-01

Light-induced rhodopsin signaling is turned off with sub-second kinetics by rhodopsin phosphorylation followed by arrestin-1 binding. To test the availability of the arrestin-1 pool in dark-adapted outer segment (OS) for rhodopsin shutoff, we measured photoresponse recovery rates of mice with arrestin-1 content in the OS of 2.5%, 5%, 60%, and 100% of wild type (WT) level by two-flash ERG with the first (desensitizing) flash at 160, 400, 1000, and 2500 photons/rod. The time of half recovery (thalf) in WT retinas increases with the intensity of the initial flash, becoming ∼2.5-fold longer upon activation of 2500 than after 160 rhodopsins/rod. Mice with 60% and even 5% of WT arrestin-1 level recovered at WT rates. In contrast, the mice with 2.5% of WT arrestin-1 had a dramatically slower recovery than the other three lines, with the thalf increasing ∼28 fold between 160 and 2500 rhodopsins/rod. Even after the dimmest flash, the rate of recovery of rods with 2.5% of normal arrestin-1 was two times slower than in other lines, indicating that arrestin-1 level in the OS between 100% and 5% of WT is sufficient for rapid recovery, whereas with lower arrestin-1 the rate of recovery dramatically decreases with increased light intensity. Thus, the OS has two distinct pools of arrestin-1: cytoplasmic and a separate pool comprising ∼2.5% that is not immediately available for rhodopsin quenching. The observed delay suggests that this pool is localized at the periphery, so that its diffusion across the OS rate-limits the recovery. The line with very low arrestin-1 expression is the first where rhodopsin inactivation was made rate-limiting by arrestin manipulation. PMID:21818392

Progressive reduction of its expression in rods reveals two pools of arrestin-1 in the outer segment with different roles in photoresponse recovery.

PubMed

Cleghorn, Whitney M; Tsakem, Elviche L; Song, Xiufeng; Vishnivetskiy, Sergey A; Seo, Jungwon; Chen, Jeannie; Gurevich, Eugenia V; Gurevich, Vsevolod V

2011-01-01

Light-induced rhodopsin signaling is turned off with sub-second kinetics by rhodopsin phosphorylation followed by arrestin-1 binding. To test the availability of the arrestin-1 pool in dark-adapted outer segment (OS) for rhodopsin shutoff, we measured photoresponse recovery rates of mice with arrestin-1 content in the OS of 2.5%, 5%, 60%, and 100% of wild type (WT) level by two-flash ERG with the first (desensitizing) flash at 160, 400, 1000, and 2500 photons/rod. The time of half recovery (t(half)) in WT retinas increases with the intensity of the initial flash, becoming ∼2.5-fold longer upon activation of 2500 than after 160 rhodopsins/rod. Mice with 60% and even 5% of WT arrestin-1 level recovered at WT rates. In contrast, the mice with 2.5% of WT arrestin-1 had a dramatically slower recovery than the other three lines, with the t(half) increasing ∼28 fold between 160 and 2500 rhodopsins/rod. Even after the dimmest flash, the rate of recovery of rods with 2.5% of normal arrestin-1 was two times slower than in other lines, indicating that arrestin-1 level in the OS between 100% and 5% of WT is sufficient for rapid recovery, whereas with lower arrestin-1 the rate of recovery dramatically decreases with increased light intensity. Thus, the OS has two distinct pools of arrestin-1: cytoplasmic and a separate pool comprising ∼2.5% that is not immediately available for rhodopsin quenching. The observed delay suggests that this pool is localized at the periphery, so that its diffusion across the OS rate-limits the recovery. The line with very low arrestin-1 expression is the first where rhodopsin inactivation was made rate-limiting by arrestin manipulation.

Volumetric topological analysis: a novel approach for trabecular bone classification on the continuum between plates and rods.

PubMed

Saha, Punam K; Xu, Yan; Duan, Hong; Heiner, Anneliese; Liang, Guoyuan

2010-11-01

Trabecular bone (TB) is a complex quasi-random network of interconnected plates and rods. TB constantly remodels to adapt to the stresses to which it is subjected (Wolff's Law). In osteoporosis, this dynamic equilibrium between bone formation and resorption is perturbed, leading to bone loss and structural deterioration. Both bone loss and structural deterioration increase fracture risk. Bone's mechanical behavior can only be partially explained by variations in bone mineral density, which led to the notion of bone structural quality. Previously, we developed digital topological analysis (DTA) which classifies plates, rods, profiles, edges, and junctions in a TB skeletal representation. Although the method has become quite popular, a major limitation of DTA is that it provides only hard classifications of different topological entities, failing to distinguish between narrow and wide plates. Here, we present a new method called volumetric topological analysis (VTA) for regional quantification of TB topology. At each TB location, the method uniquely classifies its topology on the continuum between perfect plates and perfect rods, facilitating early detections of TB alterations from plates to rods according to the known etiology of osteoporotic bone loss. Several new ideas, including manifold distance transform, manifold scale, and feature propagation have been introduced here and combined with existing DTA and distance transform methods, leading to the new VTA technology. This method has been applied to multidetector computed tomography (CT) and micro-computed tomography ( μCT) images of four cadaveric distal tibia and five distal radius specimens. Both intra- and inter-modality reproducibility of the method has been examined using repeat CT and μCT scans of distal tibia specimens. Also, the method's ability to predict experimental biomechanical properties of TB via CT imaging under in vivo conditions has been quantitatively examined and the results found are very encouraging.

Global Positioning System Antenna Fixed Height Tripod Adapter

NASA Technical Reports Server (NTRS)

Dinardo, Steven J.; Smith, Mark A.

1997-01-01

An improved Global Positioning em antenna adaptor allows fixed antenna height measurements by removably attaching an adaptor plate to a conventional surveyor's tripod. Antenna height is controlled by an antenna boom which is a fixed length rod. The antenna is attached to one end of the boom. The opposite end of the boom tapers to a point sized to fit into a depression at the center of survey markers. The boom passes through the hollow center of a universal ball joint which is mounted at the center of the adaptor plate so that the point of the rod can be fixed in the marker's central depression. The mountains of the ball joint allow the joint to be moved horizontally in any direction relative to the tripod. When the ball joint is moved horizontally, the angle between the boom and the vertical changes because the boom's position is fixed at its lower end. A spirit level attached to the rod allows an operator to determine when the boom is plumb. The position of the ball joint is adjusted horizontally until the boom is plumb. At that time the antenna is positioned exactly over the center of the monument and the elevation of the antenna is precisely set by the length of the boom.

An innovative acoustic sensor for first in-pile fission gas release determination - REMORA 3 experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenkrantz, E.; Ferrandis, J. Y.; Augereau, F.

2011-07-01

A fuel rod has been instrumented with a new design of an acoustic resonator used to measure in a non destructive way the internal rod plenum gas mixture composition. This ultrasonic sensor has demonstrated its ability to operate in pile during REMORA 3 irradiation experiment carried out in the OSIRIS Material Testing Reactor (CEA Saclay, France). Due to very severe experimental conditions such as temperature rising up to 150 deg.C and especially, high thermal fluence level up to 3.5 10{sup 19} n.cm{sup 2}, the initial sensor gas speed of sound efficiency measurement was strongly reduced due to the irradiation effectsmore » on the piezo-ceramic properties. Nevertheless, by adding a differential signal processing method to the initial data analysis procedure validated before irradiation, the gas resonance peaks were successfully extracted from the output signal. From these data, the molar fractions variations of helium and fission gas were measured from an adapted Virial state equation. Thus, with this sensor, the kinetics of gas release inside fuel rods could be deduced from the in-pile measurements and specific calculations. These data will also give information about nuclear reaction effect on piezo-ceramics sensor under high neutron and gamma flux. (authors)« less

Effect of adaptation and pulp density on bioleaching of mine waste using indigenous acidophilic bacteria

NASA Astrophysics Data System (ADS)

Cho, K.; Kim, B.; Lee, D.; Choi, N.; Park, C.

2011-12-01

Adaptation to environment is a natural phenomena that takes place in many animals, plants and microorganisms. These adapted organisms achieve stronger applicability than unadapted organisms after habitation in a specific environment for a long time. In the biohydrometallurgical industry, adaptation to special environment conditions by selective culturing is the most popular method for improving bioleaching activity of strains-although that is time consuming. This study investigated the influence of the bioleaching efficiency of mine waste under batch experimental conditions (adaptation and pulp density) using the indigenous acidophilic bacteria collected from acid mine drainage in Go-seong and Yeon-hwa, Korea. We conducted the batch experiments at the influences of parameters, such as the adaptation of bacteria and pulp density of the mine waste. In the adaptation case, the value of pH in 1'st adaptation bacteria sample exhibited lower than in 2'nd adaptation bacteria sample. And the content of both Cu and Zn at 1'st adaptation bacteria sample appeared lower than at 2'nd adaptation bacteria sample. In the SEM analysis, the rod-shaped bacteria with 1μm in length were observed on the filter paper (pore size - 0.45μm). The results of pulp density experiments revealed that the content of both Cu and Zn increased with increasing pulp density, since the increment of pulp density resulted in the enhancement of bioleaching capacity.

Calculation of photonic bandgap for 2D hexagonal and square structure base on hybrid polymer material

NASA Astrophysics Data System (ADS)

Hidayat, S.; Riveli, N.

2018-05-01

We have calculated 2D photonic crystal band gap using plane-wave expansion method. The studied model of structures is hexagonal lattice and square lattice of rod cylinder in air. We have simulated the dispersion relation of it structure using hybrid polymer as rod material. The parameter structures are nrod = 1.5, nhole = 1, and rrod = 0.25a, where a is lattice constant. We found the distributed feedback occurs at the edge of upper band or frequency at 0.66 (a/λ). In our experimental work, we have successfully fabricated the 2D photonic crystal from hybrid polymer incorporated with organic dye laser. The lasing characteristics ware investigated using strip-line excitation light of SHG Nd-YAG laser (λ=532 nm). The lasing wavelengths for hexagonal structure are observed at 606 nm and 621 nm for photonic crystal period of 400 nm and 410 nm, respectively. λ=532 nm). Whereas the square structure, the lasing wavelengths are observed at (588 nm ± 2) and (606 nm ± 2 nm) for grating period of 391 nm and 405 nm.

A novel cluster-tube self-adaptive robot hand.

PubMed

Fu, Hong; Yang, Haokun; Song, Weishu; Zhang, Wenzeng

2017-01-01

This paper proposes a novel cluster-tube self-adaptive robot hand (CTSA Hand). The CTSA Hand consists of a base, a motor, a transmission mechanism, multiple elastic tendons, and a group of sliding-tube assemblies. Each sliding-tube assembly is composed of a sliding tube, a guide rod, two springs and a hinge. When the hand grasping an object, the object pushes some sliding tubes to different positions according to the surface shape of the object, the motor pulls the tendons tight to cluster tubes. The CTSA Hand can realize self-adaptive grasping of objects of different sizes and shapes. The CTSA Hand can grasp multiple objects simultaneously because the grasping of the hand acts as many grippers in different directions and heights. The grasping forces of the hand are adjusted by a closed-loop control system with potentiometer. Experimental results show that the CTSA Hand has the features of highly self-adaption and large grasping forces when grasping various objects.

Coordinated dynamic encoding in the retina using opposing forms of plasticity

PubMed Central

Kastner, David B.; Baccus, Stephen A.

2011-01-01

The range of natural inputs encoded by a neuron often exceeds its dynamic range. To overcome this limitation, neural populations divide their inputs among different cell classes, as with rod and cone photoreceptors, and adapt by shifting their dynamic range. We report that the dynamic behavior of retinal ganglion cells in salamanders, mice, and rabbits is divided into two opposing forms of short-term plasticity in different cell classes. One population of cells exhibited sensitization—a persistent elevated sensitivity following a strong stimulus. This novel dynamic behavior compensates for the information loss caused by the known process of adaptation occurring in a separate cell population. The two populations divide the dynamic range of inputs, with sensitizing cells encoding weak signals, and adapting cells encoding strong signals. In the two populations, the linear, threshold and adaptive properties are linked to preserve responsiveness when stimulus statistics change, with one population maintaining the ability to respond when the other fails. PMID:21909086

Palaeozoic and Mesozoic tectonic implications of Central Afghanistan

NASA Astrophysics Data System (ADS)

Sliaupa, Saulius; Motuza, Gediminas

2017-04-01

The field and laboratory studies were carried out in Ghor Province situated in the central part of Afghanistan. It straddles juxtaposition of the Tajik (alternatively, North Afghanistan) and Farah Rod blocks separated by Band-e-Bayan zone. The recent studies indicate that Band-e-Bayan zone represents highly tectonised margin of the Tajik block (Motuza, Sliaupa, 2016). The Band-e-Bayan zone is the most representative in terms of sedimentary record. The subsidence trends and sediment lithologies suggest the passive margin setting during (Cambrian?) Ordovician to earliest Carboniferous times. A change to the foredeep setting is implied in middle Carboniferous through Early Permian; the large-thickness flysh-type sediments were derived from continental island arc provenance, as suggested by chemical composition of mudtstones. This stage can be correlated to the amalgamation of the Gondwana supercontinent. The new passive-margin stage can be inferred in the Band-e-Bayan zone and Tajik blocks in the Late Permian throughout the early Late Triassic that is likely related to breaking apart of Gondwana continent. A collisional event is suggested in latest Triassic, as seen in high-rate subsidence associating with dramatic change in litholgies, occurrence of volcanic rocks and granidoid intrusions. The continental volcanic island arc derived (based on geochemical indices) terrigens prevail at the base of Jurassic that were gradually replaced by carbonate platform in the Middle Jurassic pointing to cessation of the tectonic activity. A new tectonic episode (no deposition; and folding?) took place in the Tajik and Band-e-Bayan zone in Late Jurassic. The geological section of the Farah Rod block, situated to the south, is represented by Jurassic and Cretaceous sediments overlain by sporadic Cenozoic volcanic-sedimentary succession. The lower part of the Mesozoic succession is composed of terrigenic sediments giving way to upper Lower Cretaceous shallow water carbonates implying low tectonic regime. There was a break in sedimentation during the upper Cretaceous that is likely related to the Alpine orogenic event. It associated with some Upper Cretaceous magmatic activity (Debon et al., 1987). This event is reflected in the sedimentation pattern in the adjacent Band-e-Bayan zone and Tadjick block. The lower part of the Upper Cretaceous succession is composed of reddish terrigenic sediments. They are overlain by uppermost Cretaceous (and Danian) shallow marine sediments implying establishment of quiet tectonic conditions.

Kinetics of Recovery of the Dark-adapted Salamander Rod Photoresponse

PubMed Central

Nikonov, S.; Engheta, N.; Pugh, E.N.

1998-01-01

The kinetics of the dark-adapted salamander rod photocurrent response to flashes producing from 10 to 105 photoisomerizations (Φ) were investigated in normal Ringer's solution, and in a choline solution that clamps calcium near its resting level. For saturating intensities ranging from ∼102 to 104 Φ, the recovery phases of the responses in choline were nearly invariant in form. Responses in Ringer's were similarly invariant for saturating intensities from ∼103 to 104 Φ. In both solutions, recoveries to flashes in these intensity ranges translated on the time axis a constant amount (τc) per e-fold increment in flash intensity, and exhibited exponentially decaying “tail phases” with time constant τc. The difference in recovery half-times for responses in choline and Ringer's to the same saturating flash was 5–7 s. Above ∼104 Φ, recoveries in both solutions were systematically slower, and translation invariance broke down. Theoretical analysis of the translation-invariant responses established that τc must represent the time constant of inactivation of the disc-associated cascade intermediate (R*, G*, or PDE*) having the longest lifetime, and that the cGMP hydrolysis and cGMP-channel activation reactions are such as to conserve this time constant. Theoretical analysis also demonstrated that the 5–7-s shift in recovery half-times between responses in Ringer's and in choline is largely (4–6 s) accounted for by the calcium-dependent activation of guanylyl cyclase, with the residual (1–2 s) likely caused by an effect of calcium on an intermediate with a nondominant time constant. Analytical expressions for the dim-flash response in calcium clamp and Ringer's are derived, and it is shown that the difference in the responses under the two conditions can be accounted for quantitatively by cyclase activation. Application of these expressions yields an estimate of the calcium buffering capacity of the rod at rest of ∼20, much lower than previous estimates. PMID:9417132

Reactor refueling containment system

DOEpatents

Gillett, J.E.; Meuschke, R.E.

1995-05-02

A method of refueling a nuclear reactor is disclosed whereby the drive mechanism is disengaged and removed by activating a jacking mechanism that raises the closure head. The area between the barrier plate and closure head is exhausted through the closure head penetrations. The closure head, upper drive mechanism, and bellows seal are lifted away and transported to a safe area. The barrier plate acts as the primary boundary and each drive and control rod penetration has an elastomer seal preventing excessive tritium gases from escaping. The individual instrumentation plugs are disengaged allowing the corresponding fuel assembly to be sealed and replaced. 2 figs.

Reactor refueling containment system

DOEpatents

Gillett, James E.; Meuschke, Robert E.

1995-01-01

A method of refueling a nuclear reactor whereby the drive mechanism is disengaged and removed by activating a jacking mechanism that raises the closure head. The area between the barrier plate and closure head is exhausted through the closure head penetrations. The closure head, upper drive mechanism, and bellows seal are lifted away and transported to a safe area. The barrier plate acts as the primary boundary and each drive and control rod penetration has an elastomer seal preventing excessive tritium gases from escaping. The individual instrumentation plugs are disengaged allowing the corresponding fuel assembly to be sealed and replaced.

KSC-05PD-1090

NASA Technical Reports Server (NTRS)

2005-01-01

KENNEDY SPACE CENTER, FLA. On Orbiter Atlantis in NASAs Orbiter Processing Facility, bay 1, a retract link assembly (upper and lower white rods) is on the left-hand main landing gear. Last week a small crack was found on the right-hand assembly. To lower the main landing gear, a mechanical linkage released by each gear actuates the doors to the open position. The landing gear reach the full-down and extended position with 10 seconds and are locked in the down position by spring-loaded downlock bungees Atlantis is scheduled to launch in September 2005 on the second Return to Flight mission, STS-121.

Controlling gain one photon at a time

PubMed Central

Schwartz, Gregory W; Rieke, Fred

2013-01-01

Adaptation is a salient property of sensory processing. All adaptational or gain control mechanisms face the challenge of obtaining a reliable estimate of the property of the input to be adapted to and obtaining this estimate sufficiently rapidly to be useful. Here, we explore how the primate retina balances the need to change gain rapidly and reliably when photons arrive rarely at individual rod photoreceptors. We find that the weakest backgrounds that decrease the gain of the retinal output signals are similar to those that increase human behavioral threshold, and identify a novel site of gain control in the retinal circuitry. Thus, surprisingly, the gain of retinal signals begins to decrease essentially as soon as background lights are detectable; under these conditions, gain control does not rely on a highly averaged estimate of the photon count, but instead signals from individual photon absorptions trigger changes in gain. DOI: http://dx.doi.org/10.7554/eLife.00467.001 PMID:23682314

Adaptive control based on an on-line parameter estimation of an upper limb exoskeleton.

PubMed

Riani, Akram; Madani, Tarek; Hadri, Abdelhafid El; Benallegue, Abdelaziz

2017-07-01

This paper presents an adaptive control strategy for an upper-limb exoskeleton based on an on-line dynamic parameter estimator. The objective is to improve the control performance of this system that plays a critical role in assisting patients for shoulder, elbow and wrist joint movements. In general, the dynamic parameters of the human limb are unknown and differ from a person to another, which degrade the performances of the exoskeleton-human control system. For this reason, the proposed control scheme contains a supplementary loop based on a new efficient on-line estimator of the dynamic parameters. Indeed, the latter is acting upon the parameter adaptation of the controller to ensure the performances of the system in the presence of parameter uncertainties and perturbations. The exoskeleton used in this work is presented and a physical model of the exoskeleton interacting with a 7 Degree of Freedom (DoF) upper limb model is generated using the SimMechanics library of MatLab/Simulink. To illustrate the effectiveness of the proposed approach, an example of passive rehabilitation movements is performed using multi-body dynamic simulation. The aims is to maneuver the exoskeleton that drive the upper limb to track desired trajectories in the case of the passive arm movements.

Pupillometer-based objective chromatic perimetry in normal eyes and patients with retinal photoreceptor dystrophies.

PubMed

Skaat, Alon; Sher, Ifat; Kolker, Andrew; Elyasiv, Sivan; Rosenfeld, Elkana; Mhajna, Mohamad; Melamed, Shlomo; Belkin, Michael; Rotenstreich, Ygal

2013-04-17

To evaluate a novel objective perimetry using multifocal chromatic pupil light reflex in normal participants and patients with photoreceptor dysfunction, and to relate this new technique with subjective dark-adapted chromatic Goldmann perimetry. Thirty-two eyes of 17 retinitis pigmentosa (RP) or cone-rod dystrophy patients and 20 eyes of 12 healthy individuals were tested. A computerized infrared video pupillometer was used to record changes in pupil diameter in response to short- and long-wavelength stimuli (peak 485 and 640 nm, respectively; light intensity 40 cd/m(2)) at 13 different points of the 30° visual field (VF), under background illumination of 2.7 cd/m(2). The pupillary response (PR) of patients was compared with PR obtained from normal control participants. In 11 patients, the pupillary responses were also compared with their findings on dark-adapted chromatic Goldmann perimetry. Significantly reduced pupillary responses were obtained in RP patients in response to the short-wavelength stimulus in nearly all perimetric locations (P < 0.03). By contrast, in response to the long-wavelength stimulus, RP patients demonstrated significantly reduced PR mostly in peripheral locations (P ≤ 0.02). In a cone-rod dystrophy patient, the PR to both long- and short-wavelength stimuli was significantly lower in the scotoma area identified by the dark-adapted chromatic Goldmann perimetry. In all patients that were tested by the chromatic Goldmann, minimal PR was recorded in areas that were nondetected in the chromatic Goldmann perimetry. This study demonstrates the potential feasibility of using pupillometer-based chromatic perimetry for objectively assessing VF defects and retinal function in patients with retinal dystrophies. (ClinicalTrials.gov number, NCT01021982.).

Influence of background size, luminance and eccentricity on different adaptation mechanisms

PubMed Central

Gloriani, Alejandro H.; Matesanz, Beatriz M.; Barrionuevo, Pablo A.; Arranz, Isabel; Issolio, Luis; Mar, Santiago; Aparicio, Juan A.

2016-01-01

Mechanisms of light adaptation have been traditionally explained with reference to psychophysical experimentation. However, the neural substrata involved in those mechanisms remain to be elucidated. Our study analyzed links between psychophysical measurements and retinal physiological evidence with consideration for the phenomena of rod-cone interactions, photon noise, and spatial summation. Threshold test luminances were obtained with steady background fields at mesopic and photopic light levels (i.e., 0.06–110 cd/m2) for retinal eccentricities from 0° to 15° using three combinations of background/test field sizes (i.e., 10°/2°, 10°/0.45°, and 1°/0.45°). A two-channel Maxwellian view optical system was employed to eliminate pupil effects on the measured thresholds. A model based on visual mechanisms that were described in the literature was optimized to fit the measured luminance thresholds in all experimental conditions. Our results can be described by a combination of visual mechanisms. We determined how spatial summation changed with eccentricity and how subtractive adaptation changed with eccentricity and background field size. According to our model, photon noise plays a significant role to explain contrast detection thresholds measured with the 1/0.45° background/test size combination at mesopic luminances and at off-axis eccentricities. In these conditions, our data reflect the presence of rod-cone interaction for eccentricities between 6° and 9° and luminances between 0.6 and 5 cd/m2. In spite of the increasing noise effects with eccentricity, results also show that the visual system tends to maintain a constant signal-to-noise ratio in the off-axis detection task over the whole mesopic range. PMID:27210038

Influence of background size, luminance and eccentricity on different adaptation mechanisms.

PubMed

Gloriani, Alejandro H; Matesanz, Beatriz M; Barrionuevo, Pablo A; Arranz, Isabel; Issolio, Luis; Mar, Santiago; Aparicio, Juan A

2016-08-01

Mechanisms of light adaptation have been traditionally explained with reference to psychophysical experimentation. However, the neural substrata involved in those mechanisms remain to be elucidated. Our study analyzed links between psychophysical measurements and retinal physiological evidence with consideration for the phenomena of rod-cone interactions, photon noise, and spatial summation. Threshold test luminances were obtained with steady background fields at mesopic and photopic light levels (i.e., 0.06-110cd/m(2)) for retinal eccentricities from 0° to 15° using three combinations of background/test field sizes (i.e., 10°/2°, 10°/0.45°, and 1°/0.45°). A two-channel Maxwellian view optical system was employed to eliminate pupil effects on the measured thresholds. A model based on visual mechanisms that were described in the literature was optimized to fit the measured luminance thresholds in all experimental conditions. Our results can be described by a combination of visual mechanisms. We determined how spatial summation changed with eccentricity and how subtractive adaptation changed with eccentricity and background field size. According to our model, photon noise plays a significant role to explain contrast detection thresholds measured with the 1/0.45° background/test size combination at mesopic luminances and at off-axis eccentricities. In these conditions, our data reflect the presence of rod-cone interaction for eccentricities between 6° and 9° and luminances between 0.6 and 5cd/m(2). In spite of the increasing noise effects with eccentricity, results also show that the visual system tends to maintain a constant signal-to-noise ratio in the off-axis detection task over the whole mesopic range. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structure of the integument of southern right whales, Eubalaena australis.

PubMed

Reeb, Desray; Best, Peter Barrington; Kidson, Susan Hillary

2007-06-01

Skin (integument) anatomy reflects adaptations to particular environments. It is hypothesized that cetacean (whale) integument will show unique anatomical adaptations to an aquatic environment, particularly regarding differences in temperature, density, and pressure. In this study, the gross and histological structure of the southern right whale integument is described and compared with terrestrial mammals and previous descriptions of mysticete (baleen whale) and odontocete (toothed whale) species. Samples were taken of the integument of 98 free-swimming southern right whales, Eubalaena australis, and examined by both light and electron microscopy. Results show that three epidermal layers are present, with the stratum corneum being parakeratotic in nature. As in bowhead whales, southern right whales possess an acanthotic epidermis and a notably thick hypodermis, with epidermal rods and extensive papillomatosis. However, unlike bowhead whales, southern right whales possess an uninterrupted hypodermal layer. Surprisingly, the integument of balaenids (right and bowhead mysticetes) in general is more like that of odontocetes than that of the more closely related balaenopterids (rorqual mysticetes). Similarities to odontocetes were found specifically in the collagen fibers in a fat-free zone of the reticular dermal layer and the elastic fibers in the dermal and hypodermal layers. Callosities, a distinctive feature of this genus, have a slightly thicker stratum corneum and are usually associated with hairs that have innervated and vascularized follicles. These hairs may function as vibrissae, thus aiding in aquatic foraging by allowing rapid detection of changes in prey density. Although the thick insulatory integument makes right whales bulky and slow-moving, it is an adaptation for living in cold water. Epidermal thickness, presence of epidermal rods, and callosities may act as barriers against mechanical injury from bodily contact with conspecifics or hard surfaces in the environment (e.g., rocks, ice). 2007 Wiley-Liss, Inc.

Photon Hunting in the Twilight Zone: Visual Features of Mesopelagic Bioluminescent Sharks

PubMed Central

Claes, Julien M.; Partridge, Julian C.; Hart, Nathan S.; Garza-Gisholt, Eduardo; Ho, Hsuan-Ching; Mallefet, Jérôme; Collin, Shaun P.

2014-01-01

The mesopelagic zone is a visual scene continuum in which organisms have developed various strategies to optimize photon capture. Here, we used light microscopy, stereology-assisted retinal topographic mapping, spectrophotometry and microspectrophotometry to investigate the visual ecology of deep-sea bioluminescent sharks [four etmopterid species (Etmopterus lucifer, E. splendidus, E. spinax and Trigonognathus kabeyai) and one dalatiid species (Squaliolus aliae)]. We highlighted a novel structure, a translucent area present in the upper eye orbit of Etmopteridae, which might be part of a reference system for counterillumination adjustment or acts as a spectral filter for camouflage breaking, as well as several ocular specialisations such as aphakic gaps and semicircular tapeta previously unknown in elasmobranchs. All species showed pure rod hexagonal mosaics with a high topographic diversity. Retinal specialisations, formed by shallow cell density gradients, may aid in prey detection and reflect lifestyle differences; pelagic species display areae centrales while benthopelagic and benthic species display wide and narrow horizontal streaks, respectively. One species (E. lucifer) displays two areae within its horizontal streak that likely allows detection of conspecifics' elongated bioluminescent flank markings. Ganglion cell topography reveals less variation with all species showing a temporal area for acute frontal binocular vision. This area is dorsally extended in T. kabeyai, allowing this species to adjust the strike of its peculiar jaws in the ventro-frontal visual field. Etmopterus lucifer showed an additional nasal area matching a high rod density area. Peak spectral sensitivities of the rod visual pigments (λmax) fall within the range 484–491 nm, allowing these sharks to detect a high proportion of photons present in their habitat. Comparisons with previously published data reveal ocular differences between bioluminescent and non-bioluminescent deep-sea sharks. In particular, bioluminescent sharks possess higher rod densities, which might provide them with improved temporal resolution particularly useful for bioluminescent communication during social interactions. PMID:25099504

Photon hunting in the twilight zone: visual features of mesopelagic bioluminescent sharks.

PubMed

Claes, Julien M; Partridge, Julian C; Hart, Nathan S; Garza-Gisholt, Eduardo; Ho, Hsuan-Ching; Mallefet, Jérôme; Collin, Shaun P

2014-01-01

The mesopelagic zone is a visual scene continuum in which organisms have developed various strategies to optimize photon capture. Here, we used light microscopy, stereology-assisted retinal topographic mapping, spectrophotometry and microspectrophotometry to investigate the visual ecology of deep-sea bioluminescent sharks [four etmopterid species (Etmopterus lucifer, E. splendidus, E. spinax and Trigonognathus kabeyai) and one dalatiid species (Squaliolus aliae)]. We highlighted a novel structure, a translucent area present in the upper eye orbit of Etmopteridae, which might be part of a reference system for counterillumination adjustment or acts as a spectral filter for camouflage breaking, as well as several ocular specialisations such as aphakic gaps and semicircular tapeta previously unknown in elasmobranchs. All species showed pure rod hexagonal mosaics with a high topographic diversity. Retinal specialisations, formed by shallow cell density gradients, may aid in prey detection and reflect lifestyle differences; pelagic species display areae centrales while benthopelagic and benthic species display wide and narrow horizontal streaks, respectively. One species (E. lucifer) displays two areae within its horizontal streak that likely allows detection of conspecifics' elongated bioluminescent flank markings. Ganglion cell topography reveals less variation with all species showing a temporal area for acute frontal binocular vision. This area is dorsally extended in T. kabeyai, allowing this species to adjust the strike of its peculiar jaws in the ventro-frontal visual field. Etmopterus lucifer showed an additional nasal area matching a high rod density area. Peak spectral sensitivities of the rod visual pigments (λmax) fall within the range 484-491 nm, allowing these sharks to detect a high proportion of photons present in their habitat. Comparisons with previously published data reveal ocular differences between bioluminescent and non-bioluminescent deep-sea sharks. In particular, bioluminescent sharks possess higher rod densities, which might provide them with improved temporal resolution particularly useful for bioluminescent communication during social interactions.

THE VISUAL DISCRIMINATION OF INTENSITY AND THE WEBER-FECHNER LAW

PubMed Central

Hecht, Selig

1924-01-01

1. A study of the historical development of the Weber-Fechner law shows that it fails to describe intensity perception; first, because it is based on observations which do not record intensity discrimination accurately, and second, because it omits the essentially discontinuous nature of the recognition of intensity differences. 2. There is presented a series of data, assembled from various sources, which proves that in the visual discrimination of intensity the threshold difference ΔI bears no constant relation to the intensity I. The evidence shows unequivocally that as the intensity rises, the ratio See PDF for Equation first decreases and then increases. 3. The data are then subjected to analysis in terms of a photochemical system already proposed for the visual activity of the rods and cones. It is found that for the retinal elements to discriminate between one intensity and the next perceptible one, the transition from one to the other must involve the decomposition of a constant amount of photosensitive material. 4. The magnitude of this unitary increment in the quantity of photochemical action is greater for the rods than for the cones. Therefore, below a certain critical illumination—the cone threshold—intensity discrimination is controlled by the rods alone, but above this point it is determined by the cones alone. 5. The unitary increments in retinal photochemical action may be interpreted as being recorded by each rod and cone; or as conditioning the variability of the retinal cells so that each increment involves a constant increase in the number of active elements; or as a combination of the two interpretations. 6. Comparison with critical data of such diverse nature as dark adaptation, absolute thresholds, and visual acuity shows that the analysis is consistent with well established facts of vision. PMID:19872133

Understanding Climate Adaptation on Public Lands in the Upper Midwest: Implications for Monitoring and Tracking Progress

NASA Astrophysics Data System (ADS)

Anhalt-Depies, Christine M.; Knoot, Tricia Gorby; Rissman, Adena R.; Sharp, Anthony K.; Martin, Karl J.

2016-05-01

There are limited examples of efforts to systematically monitor and track climate change adaptation progress in the context of natural resource management, despite substantial investments in adaptation initiatives. To better understand the status of adaptation within state natural resource agencies, we utilized and problematized a rational decision-making framework to characterize adaptation at the level of public land managers in the Upper Midwest. We conducted in-depth interviews with 29 biologists and foresters to provide an understanding of managers' experiences with, and perceptions of, climate change impacts, efforts towards planning for climate change, and a full range of actions implemented to address climate change. While the majority of managers identified climate change impacts affecting their region, they expressed significant uncertainty in interpreting those signals. Just under half of managers indicated planning efforts are underway, although most planning is remote from local management. Actions already implemented include both forward-looking measures and those aimed at coping with current impacts. In addition, cross-scale dynamics emerged as an important theme related to the overall adaptation process. The results hold implications for tracking future progress on climate change adaptation. Common definitions or measures of adaptation (e.g., presence of planning documents) may need to be reassessed for applicability at the level of public land managers.

Understanding Climate Adaptation on Public Lands in the Upper Midwest: Implications for Monitoring and Tracking Progress.

PubMed

Anhalt-Depies, Christine M; Knoot, Tricia Gorby; Rissman, Adena R; Sharp, Anthony K; Martin, Karl J

2016-05-01

There are limited examples of efforts to systematically monitor and track climate change adaptation progress in the context of natural resource management, despite substantial investments in adaptation initiatives. To better understand the status of adaptation within state natural resource agencies, we utilized and problematized a rational decision-making framework to characterize adaptation at the level of public land managers in the Upper Midwest. We conducted in-depth interviews with 29 biologists and foresters to provide an understanding of managers' experiences with, and perceptions of, climate change impacts, efforts towards planning for climate change, and a full range of actions implemented to address climate change. While the majority of managers identified climate change impacts affecting their region, they expressed significant uncertainty in interpreting those signals. Just under half of managers indicated planning efforts are underway, although most planning is remote from local management. Actions already implemented include both forward-looking measures and those aimed at coping with current impacts. In addition, cross-scale dynamics emerged as an important theme related to the overall adaptation process. The results hold implications for tracking future progress on climate change adaptation. Common definitions or measures of adaptation (e.g., presence of planning documents) may need to be reassessed for applicability at the level of public land managers.

A proteomic approach to the analysis of the components of the phycobilisomes from two cyanobacteria with complementary chromatic adaptation: Fremyella diplosiphon UTEX B590 and Tolypothrix PCC 7601.

PubMed

Pérez-Gómez, Bertha; Mendoza-Hernández, Guillermo; Cabellos-Avelar, Tecilli; Leyva-Castillo, Lourdes Elizabeth; Gutiérrez-Cirlos, Emma Berta; Gómez-Lojero, Carlos

2012-10-01

Tolypothrix PCC 7601 and Fremyella diplosiphon UTEX B590 can produce two alternative phycobilisome (PBS) rods. PE-PBSs with one phycocyanin (PC) disk and multiple phycoerythrin (PE) disks are found in cells grown under green light (GL). PC-PBSs with only PC disks are obtained from cells grown under red light (RL). In this manuscript, we show the localization of the linker proteins and ferredoxin-NADP(+) oxidoreductase (FNR) in the PC-PBS and of PE-PBS rods using visible spectroscopy and mass spectrometry. PE-PBSs with different [PE]/[PC] ratios and PC-PBSs with different [PC]/[AP] (AP, allophycocyanin) ratios were isolated. CpeC was the primary rod linker protein found in the PBSs with a [PE]/[PC] ratio of 1.1, which indicates that this is the rod linker at the interphase PC-PE. CpeC and CpeD were identified in the PBSs with a [PE]/[PC] ratio of 1.6, which indicates that CpcD is the linker between the first and the second PE hexamers. Finally, CpeC, CpeD, and CpeE were found in the PBSs with a [PE]/[PC] ratio of 2.9, indicating the position of CpeE between the second and third PE moieties. CpcI2 was identified in the two PC-PBSs obtained from cells grown under RL, which indicates that CpcI2 is the linker between the first and second PC hexamers. CpcH2 was identified only in the PC-PBSs from Tolypothrix with a high [PC]/[AP] ratio of 1.92, which indicates that CpcH2 is the linker between the second and third PC hexamers. The PC-PBSs contained the rod cap protein L(R)(10) (CpcD), but this protein was absent in the PE-PBSs. PE-PBSs (lacking L(R)(10)) incorporated exogenous rFNR in a stoichiometry of up to five FNRs per PBS. A maximum of two FNRs per PBS were found in PC-PBSs (with L(R)(10)). These observations support the hypothesis that FNR binds at the distal ends of the PBS rods in the vacant site of CpcD L(R)(10). Finally, the molecular mass of the core membrane linker (L(CM)) was determined to be 102 kDa from a mass spectrometry analysis.

The saturation of monochromatic lights obliquely incident on the retina.

PubMed Central

Alpern, M; Tamaki, R

1983-01-01

Foveal dark-adaptation undertaken to test the hypothesis that the excitation of rods causes the desaturation of 'yellow' lights in a 1 degree field traversing the margin of the pupil, fails to exclude that possibility. The desaturation is largest for a 1 degree outside diameter annular test, is still measurable with a 0.5 degree circular disk, but disappears for a 0.29 degree disk. The supersaturation of obliquely incident 501.2 nm test light follows the opposite pattern; it disappears with an annulus and is largest for a 0.29 degree circular field. It is unlikely that rods replace short-wave sensitive cones in the trichromatic match of an obliquely incident test with normally incident primaries. If rods as well as all three cones species are involved, the matches might not be trichromatic in the strong sense. Grassmann's law of scalar multiplication was tested and shown not to hold for the match of an obliquely incident test with normally incident primaries, though it remains valid whenever, both primaries and test strike the retina at the same angle of incidence (independent of that angle). The result in section 3 (above) cannot be due to rod intrusion. It persists (and becomes more conspicuous) on backgrounds (4.0 log scotopic td) which saturate rods. Moreover obliquely incident 'yellow' lights remain desaturated in intervals in the dark after a full bleach, whilst the test field is below rod threshold. The amount of desaturation does not differ appreciably from that normally found. The assumption of the unified theory of Alpern, Kitahara & Tamaki (1983) that the outer segments of only a single set of three cone species (with acceptance angles wide enough to include the entire exit pupil) contain the visual pigments absorbing both the normally incident primaries and the obliquely incident test is disproved by these results. Failure of Grassmann's law is most conspicuous under the conditions for which the changes in saturation upon changing from normal to oblique incidence are greatest and least when the saturation changes are the smallest. Either all unified theories of the Stiles-Crawford effects are wrong or all the effects of oblique incidence operate at a stage in the visual process at which the effects of radiation of different wave-lengths are no longer compounded by the simple linear laws. PMID:6875976

A biomechanical evaluation to optimize the configuration of a hinged external fixator for the primary treatment of severely displaced intraarticular calcaneus fractures with soft tissue damage.

PubMed

Besch, Lutz; Schmidt, Ina; Mueller, Michael; Daniels-Wredenhagen, Mark; Hilgert, Ralf-Eric; Varoga, Deike; Seekamp, Andreas

2008-01-01

The purpose of this investigation was to develop an optimized hinged external fixator for the primary treatment of dislocated, intra-articular calcaneus fractures with associated soft tissue damage. To this end, a calcaneus model was made out of a polyurethane block, and a steel cylinder served as the ankle joint and was connected to a synthetic model of the tibia via a metal clamp. A saw cut served as the fracture in the model. A Steinmann nail and Schanz screw were placed in defined positions in the model and connected medially and laterally with longitudinal support rods. The fixator allowed a total of 20 degrees of plantar- and dorsiflexion, with rotation in the virtual axis of the upper ankle joint. Changes in the model fracture were measured during cyclical strain, and at different screw positions in the model tibia and calcaneus. Miniature force sensors located on the longitudinal support rods, and a plantar tension spring, were used to measure pressure and tension. Reproducible values were determined and, with the optimal configuration, shifting within the osteotomy was minimal. In the experimental configuration, optimal tibial screw placement was 70 mm proximal to the rotation axis of the upper ankle joint, and optimal placement of the Steinmann nail was in the posterior surface of the calcaneus. These findings indicated that the hinged fixator allows 20 degrees of ankle movement without alteration of the rotation axis, and suggest that this type of external fixator can be used in all types of calcaneal fracture regardless of the soft tissue damage. ACFAS Level of Clinical Evidence: 5c.

Spare the rod and spoil the child. Is this a sensible justification for the use of punishment in child rearing?

PubMed

Carey, T A

1994-12-01

This paper examines the validity of the well-used proverb Spare the rod and spoil the child. To do this, the original form of the proverb from the Bible is compared with the modern form, and some significant differences are highlighted. The definition of punishment is considered, and the differences between punishment and corporal punishment are examined. Punishment is explored in some detail with attention given to the criteria that need to be satisfied in order for punishment to be effective. Discrepancies in the literature concerning these criteria are pointed out, making punishment a complex issue. The negative effects of punishment are significant with links to social problems such as teenage delinquency and violence. Reference is made to cultures where corporal punishment has been banned and the effects of this action. Given the problems associated with punishment programs, especially those being used in families, alternatives to punishment are discussed. Finally, an alternative form of the proverb to the current adaptation is offered.

Dark adaptation of toad rod photoreceptors following small bleaches.

PubMed

Leibrock, C S; Reuter, T; Lamb, T D

1994-11-01

The recovery of toad rod photoreceptors, following exposure to intense lights that bleached 0.02-3% of the rhodopsin, has been investigated using the suction pipette technique. The post-bleach period was accompanied by reduced flash sensitivity, accelerated kinetics, and spontaneous fluctuations (noise). The power spectrum of the fluctuations had substantially the form expected for the random occurrence of single-photon events, and the noise could therefore be expressed as a "photon-noise equivalent intensity". From the level of desensitization at any time, the after-effect of the bleach could also be expressed in terms of a "desensitization-equivalent intensity", and this was found to be at least a factor of 20 times higher than the noise-equivalent intensity at the corresponding time. Our results indicate that a bleach induces two closely-related phenomena: (a) a process indistinguishable from the effect of real light, and (b) another process which desensitizes and accelerates the response in the same way that light does, but without causing photon-like noise. We propose a mechanism underlying these processes.

Specific Adaptation of Gas Atomization Processing for Al-Based Alloy Powder for Additive Manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Iver; Siemon, John

The charge for each gas atomization experiment was provided by Alcoa and consisted of cast blocks cut into 1 inch by 1 inch square rods of the chosen aluminum alloys. The atmosphere in the melting chamber and connected atomization system was evacuated with a mechanical pump prior to backfilling with ultrahigh purity (UHP grade) Ar. The melt was contained in a bottom tapped alumina crucible with an alumina stopper rod to seal the exit while heating to a pouring temperature of 1000 – 1400°C. When the desired superheat was reached, the stopper rod was lifted and melt flowed through pourmore » tube and was atomized with Ar from a 45-22-052-409 gas atomization nozzle (or atomization die), having a jet apex angle of 45 degrees with 22 cylindrical gas jets (each with diameter of 1.32 mm or 0.052 inches) arrayed around the axis of a 10.4 mm central bore. The Ar atomization gas supply regulator pressure was set to produce nozzle manifold pressures for the series of runs at pressures of 250-650 psi. Secondary gas halos of Ar+O 2 and He also were added to the interior of the spray chamber at various downstream locations for additional cooling of the atomized droplets, surface passivation, and to prevent coalescence of the resulting powder.« less

Structure of myosin filaments from relaxed Lethocerus flight muscle by cryo-EM at 6 Å resolution

PubMed Central

Hu, Zhongjun; Taylor, Dianne W.; Reedy, Michael K.; Edwards, Robert J.; Taylor, Kenneth A.

2016-01-01

We describe a cryo–electron microscopy three-dimensional image reconstruction of relaxed myosin II–containing thick filaments from the flight muscle of the giant water bug Lethocerus indicus. The relaxed thick filament structure is a key element of muscle physiology because it facilitates the reextension process following contraction. Conversely, the myosin heads must disrupt their relaxed arrangement to drive contraction. Previous models predicted that Lethocerus myosin was unique in having an intermolecular head-head interaction, as opposed to the intramolecular head-head interaction observed in all other species. In contrast to the predicted model, we find an intramolecular head-head interaction, which is similar to that of other thick filaments but oriented in a distinctly different way. The arrangement of myosin’s long α-helical coiled-coil rod domain has been hypothesized as either curved layers or helical subfilaments. Our reconstruction is the first report having sufficient resolution to track the rod α helices in their native environment at resolutions ~5.5 Å, and it shows that the layer arrangement is correct for Lethocerus. Threading separate paths through the forest of myosin coiled coils are four nonmyosin peptides. We suggest that the unusual position of the heads and the rod arrangement separated by nonmyosin peptides are adaptations for mechanical signal transduction whereby applied tension disrupts the myosin heads as a component of stretch activation. PMID:27704041

Effect of hydroxylamine on photon-like events during dark adaptation in toad rod photoreceptors.

PubMed Central

Leibrock, C S; Lamb, T D

1997-01-01

1. The suction pipette technique was used to investigate the recovery of toad rod photoreceptors following small bleaches of 0.2-3% of the rhodopsin. 2. The reduction in sensitivity and the increase in noise elicited by bleaches were measured, and from these measurements the underlying rate of occurrence of photon-like events was calculated as a function of time after the bleach. 3. Exposure to hydroxylamine solution was used to hasten the decomposition of the metarhodopsin photoproducts. The outer segment was exposed to 110 mM hydroxylamine in a low-Ca2+ Ringer solution for a period of 10-50 s beginning 10-17 min after the bleaching exposure. 4. By the time of the hydroxylamine exposure, the flash sensitivity and response kinetics had returned almost to normal, and were not significantly altered by the exposure. 5. Following hydroxylamine exposure, the rate of spontaneous photon-like events in the rods declined rapidly to near pre-bleach levels. 6. We conclude that hydroxylamine reduces the rate of occurrence of photon-like events induced by a bleach, and we postulate that this reduction results from the removal of metarhodopsin (most likely metarhodopsin II) from the outer segment. 7. Our results are consistent with a model in which photon-like events result from reversal of the reactions (phosphorylation and capping by arrestin) that lead to inactivation of the activated form of rhodopsin, Rh*. PMID:9174997

Use of Imipenem To Detect KPC, NDM, OXA, IMP, and VIM Carbapenemase Activity from Gram-Negative Rods in 75 Minutes Using Liquid Chromatography-Tandem Mass Spectrometry

PubMed Central

Kulkarni, M. V.; Zurita, A. N.; Pyka, J. S.; Murray, T. S.; Hodsdon, M. E.

2014-01-01

Resistance to extended-spectrum β-lactam antibiotics has led to a greater reliance upon carbapenems, but the expression of carbapenemases threatens to limit the utility of these drugs. Current methods to detect carbapenemase activity are suboptimal, requiring prolonged incubations during which ineffective therapy may be prescribed. We previously described a sensitive and specific assay for the detection of carbapenemase activity using ertapenem and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In this study, we assessed 402 Gram-negative rods, including both Enterobacteriaceae and non-Enterobacteriaceae expressing IMP, VIM, KPC, NDM, and/or OXA carbapenemases, by using imipenem, meropenem, and ertapenem with LC-MS/MS assays. LC-MS/MS methods for the detection of intact and hydrolyzed carbapenems from an enrichment broth were developed. No ion suppression was observed, and the limits of detection for all three drugs were below 0.04 μg/ml. The sensitivity and specificity of meropenem and ertapenem for carbapenemase activity among non-Enterobacteriaceae were low, but imipenem demonstrated a sensitivity and specificity of 96% and 95%, respectively, among all Gram-negative rods (GNR) tested, including both Enterobacteriaceae and non-Enterobacteriaceae. LC-MS/MS allows for the analysis of more complex matrices, and this LC-MS/MS assay could easily be adapted for use with primary specimens requiring growth enrichment. PMID:24789180

Arrangement for controlled engagement of the tools of a mining machine with a mine face

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blumenthal, G.; Bollmann, A.

1981-07-28

An arrangement for controlled engagement of the tools of a coal planer, with a mine face comprises a scraper conveyor, provided on its front face directed toward the mine face with a guide rail guiding the coal planer for reciprocation along the mine face and a mechanism for tilting the conveyor and the coal planer about a substantially horizontal axis. The tilting mechanism is connected to the rear face of the conveyor and extends in its entirety rearwardly of the rear face of the latter. The tilting mechanism comprises a guide linkage pivotally connected at its front end to themore » rear face of the scraper conveyor while its rear end portion forms a housing for a fluid operated cylinder and piston unit, the piston rod of which is connected to a connecting rod guided by the guide linkage for movement in longitudinal direction and having an upwardly extending front section pivotally connected at its upper free end to the rear face of the scraper conveyor. The fluid operated cylinder-and-piston unit is thus considerably spaced from the scraper conveyor and the material transported thereby and especially coal dust raised during transport of the mined coal by the conveyor, whereby maintenance of the tilting unit is reduced. The guide linkage, the connecting rod and the tilting unit are all in close vicinity to the sole of the mine gallery to leave a considerable free space between the arrangement and the roof of the mine gallery.« less

Upper intestinal lipids regulate energy and glucose homeostasis.

PubMed

Cheung, Grace W C; Kokorovic, Andrea; Lam, Tony K T

2009-09-01

Upon the entry of nutrients into the small intestine, nutrient sensing mechanisms are activated to allow the body to adapt appropriately to the incoming nutrients. To date, mounting evidence points to the existence of an upper intestinal lipid-induced gut-brain neuronal axis to regulate energy homeostasis. Moreover, a recent discovery has also revealed an upper intestinal lipid-induced gut-brain-liver neuronal axis involved in the regulation of glucose homeostasis. In this mini-review, we will focus on the mechanisms underlying the activation of these respective neuronal axes by upper intestinal lipids.

Studio optics: Adapting interactive engagement pedagogy to upper-division physics

NASA Astrophysics Data System (ADS)

Sorensen, Christopher M.; McBride, Dyan L.; Rebello, N. Sanjay

2011-03-01

The use of interactive engagement strategies to improve learning in introductory physics is not new, but have not been used as often for upper-division physics courses. We describe the development and implementation of a Studio Optics course for upper-division physics majors at Kansas State University. The course adapts a three-stage Karplus learning cycle and other elements to foster an environment that promotes learning through an integration of lecture, laboratories, and problem solving. Some of the instructional materials are described. We discuss the evaluation of the course using data collected from student interviews, a conceptual survey, an attitudinal survey, and the instructor's reflections. Overall, students responded positively to the new format and showed modest gains in learning. The instructor's experiences compared favorably with the traditional course that he had taught in the past.

Can-out hatch assembly and positioning system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basnar, P.J.; Frank, R.C.; Hoh, J.C.

1985-07-03

A can-out hatch assembly is adapted to engage in a sealed manner the upper end of a covered sealed container around an aperture in a sealed chamber and to remove the cover from the container permitting a contaminant to be transferred between the container and the chamber while isolating internal portions of the container and chamber from the surrounding environment. A swing bracket is coupled at a first end thereof to the inner, lower wall of the sealed container adjacent to the aperture therein. To a second end of the swing bracket is mounted a hatch cover which may bemore » positioned in sealed engagement about the chamber's aperture by rotating the hatch cover in a first direction when the swing bracket is in the full down position. Rotation of the hatch cover in a second direction release it from sealed engagement with the chamber's aperture. A lid support rod also coupled to the second end of the swing bracket and inserted through an aperture in the center of the hatch cover may be rotated for theadably engaging the container's cover whereupon the cover may be removed from the container and the hatch cover displaced from the aperture by pivoting displacement of the swing bracket. The contaminant may then be either removed from the container and placed within the sealed chamber, or vice versa, followed by positioning of the cover upon the container and the hatch cover over the aperture in a sealed manner.« less

Can-out hatch assembly and positioning system

DOEpatents

Basnar, P.J.; Frank, R.C.; Hoh, J.C.

1985-07-03

A can-out hatch assembly is adapted to engage in a sealed manner the upper end of a covered sealed container around an aperture in a sealed chamber and to remove the cover from the container permitting a contaminant to be transferred between the container and the chamber while isolating internal portions of the container and chamber from the surrounding environment. A swing bracket is coupled at a first end thereof to the inner, lower wall of the sealed container adjacent to the aperture therein. To a second end of the swing bracket is mounted a hatch cover which may be positioned in sealed engagement about the chamber's aperture by rotating the hatch cover in a first direction when the swing bracket is in the full down position. Rotation of the hatch cover in a second direction release it from sealed engagement with the chamber's aperture. A lid support rod also coupled to the second end of the swing bracket and inserted through an aperture in the center of the hatch cover may be rotated for theadably engaging the container's cover whereupon the cover may be removed from the container and the hatch cover displaced from the aperture by pivoting displacement of the swing bracket. The contaminant may then be either removed from the container and placed within the sealed chamber, or vice versa, followed by positioning of the cover upon the container and the hatch cover over the aperture in a sealed manner.

Can-out hatch assembly and positioning system

DOEpatents

Basnar, Paul J.; Frank, Robert C.; Hoh, Joseph C.

1986-01-01

A can-out hatch assembly is adapted to engage in a sealed manner the upper end of a covered sealed container around an aperture in a sealed chamber and to remove the cover from the container permitting a contaminant to be transferred between the container and the chamber while isolating internal portions of the container and chamber from the surrounding environment. A swing bracket is coupled at a first end thereof to the inner, lower wall of the sealed container adjacent to the aperture therein. To a second end of the swing bracket is mounted a hatch cover which may be positioned in sealed engagement about the chamber's aperture by rotating the hatch cover in a first direction when the swing bracket is in the full down position. Rotation of the hatch cover in a second direction releases it from sealed engagement with the chamber's aperture. A lid support rod also coupled to the second end of the swing bracket and inserted through an aperture in the center of the hatch cover may be rotated for threadably engaging the container's cover whereupon the cover may be removed from the container and the hatch cover displaced from the aperture by pivoting displacement of the swing bracket. The contaminant may then be either removed from the container and placed within the sealed chamber, or vice versa, followed by positioning of the cover upon the container and the hatch cover over the aperture in a sealed manner.

Can-out hatch assembly and positioning system

DOEpatents

Basnar, Paul J.; Frank, Robert C.; Hoh, Joseph C.

1986-01-07

A can-out hatch assembly is adapted to engage in a sealed manner the upper end of a covered sealed container around an aperture in a sealed chamber and to remove the cover from the container permitting a contaminant to be transferred between the container and the chamber while isolating internal portions of the container and chamber from the surrounding environment. A swing bracket is coupled at a first end thereof to the inner, lower wall of the sealed container adjacent to the aperture therein. To a second end of the swing bracket is mounted a hatch cover which may be positioned in sealed engagement about the chamber's aperture by rotating the hatch cover in a first direction when the swing bracket is in the full down position. Rotation of the hatch cover in a second direction releases it from sealed engagement with the chamber's aperture. A lid support rod also coupled to the second end of the swing bracket and inserted through an aperture in the center of the hatch cover may be rotated for threadably engaging the container's cover whereupon the cover may be removed from the container and the hatch cover displaced from the aperture by pivoting displacement of the swing bracket. The contaminant may then be either removed from the container and placed within the sealed chamber, or vice versa, followed by positioning of the cover upon the container and the hatch cover over the aperture in a sealed manner.

Task-oriented rehabilitation robotics.

PubMed

Schweighofer, Nicolas; Choi, Younggeun; Winstein, Carolee; Gordon, James

2012-11-01

Task-oriented training is emerging as the dominant and most effective approach to motor rehabilitation of upper extremity function after stroke. Here, the authors propose that the task-oriented training framework provides an evidence-based blueprint for the design of task-oriented robots for the rehabilitation of upper extremity function in the form of three design principles: skill acquisition of functional tasks, active participation training, and individualized adaptive training. The previous robotic systems that incorporate elements of task-oriented trainings are then reviewed. Finally, the authors critically analyze their own attempt to design and test the feasibility of a TOR robot, ADAPT (Adaptive and Automatic Presentation of Tasks), which incorporates the three design principles. Because of its task-oriented training-based design, ADAPT departs from most other current rehabilitation robotic systems: it presents realistic functional tasks in which the task goal is constantly adapted, so that the individual actively performs doable but challenging tasks without physical assistance. To maximize efficacy for a large clinical population, the authors propose that future task-oriented robots need to incorporate yet-to-be developed adaptive task presentation algorithms that emphasize acquisition of fine motor coordination skills while minimizing compensatory movements.

Design and test of a Microsoft Kinect-based system for delivering adaptive visual feedback to stroke patients during training of upper limb movement.

PubMed

Simonsen, Daniel; Popovic, Mirjana B; Spaich, Erika G; Andersen, Ole Kæseler

2017-11-01

The present paper describes the design and test of a low-cost Microsoft Kinect-based system for delivering adaptive visual feedback to stroke patients during the execution of an upper limb exercise. Eleven sub-acute stroke patients with varying degrees of upper limb function were recruited. Each subject participated in a control session (repeated twice) and a feedback session (repeated twice). In each session, the subjects were presented with a rectangular pattern displayed on a vertical mounted monitor embedded in the table in front of the patient. The subjects were asked to move a marker inside the rectangular pattern by using their most affected hand. During the feedback session, the thickness of the rectangular pattern was changed according to the performance of the subject, and the color of the marker changed according to its position, thereby guiding the subject's movements. In the control session, the thickness of the rectangular pattern and the color of the marker did not change. The results showed that the movement similarity and smoothness was higher in the feedback session than in the control session while the duration of the movement was longer. The present study showed that adaptive visual feedback delivered by use of the Kinect sensor can increase the similarity and smoothness of upper limb movement in stroke patients.

SU-E-I-38: Improved Metal Artifact Correction Using Adaptive Dual Energy Calibration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, X; Elder, E; Roper, J

2015-06-15

Purpose: The empirical dual energy calibration (EDEC) method corrects for beam-hardening artifacts, but shows limited performance on metal artifact correction. In this work, we propose an adaptive dual energy calibration (ADEC) method to correct for metal artifacts. Methods: The empirical dual energy calibration (EDEC) method corrects for beam-hardening artifacts, but shows limited performance on metal artifact correction. In this work, we propose an adaptive dual energy calibration (ADEC) method to correct for metal artifacts. Results: Highly attenuating copper rods cause severe streaking artifacts on standard CT images. EDEC improves the image quality, but cannot eliminate the streaking artifacts. Compared tomore » EDEC, the proposed ADEC method further reduces the streaking resulting from metallic inserts and beam-hardening effects and obtains material decomposition images with significantly improved accuracy. Conclusion: We propose an adaptive dual energy calibration method to correct for metal artifacts. ADEC is evaluated with the Shepp-Logan phantom, and shows superior metal artifact correction performance. In the future, we will further evaluate the performance of the proposed method with phantom and patient data.« less

Spatial consequences of bleaching adaptation in cat retinal ganglion cells.

PubMed Central

Bonds, A B; Enroth-Cugell, C

1981-01-01

1. Experiments were conducted to study the effects of localized bleaching on the centre responses of rod-driven cat retinal ganglion cells. 2. Stimulation as far as 2 degrees from the bleaching site yielded responses which were reduced nearly as much as those generated at the bleaching site. Bleaching in the receptive field middle reduced responsiveness at a site 1 degrees peripheral more than bleaching at that peripheral site itself. 3. The effectiveness of a bleach in reducing centre responsiveness is related to the sensitivity of the region in which the bleach is applied. 4. Response reduction after a 0.2 degree bleach followed the same temporal pattern for concentric test spots of from 0.2 to 1.8 degrees in diameter, implying a substantially uniform spread of adaptation within these bounds. 5. A linear trade-off between fraction of rhodopsin and area bleached over a range of 8:1 yields the same pattern of response reduction, implying that the non-linear nature of bleaching adaptation is a property of the adaptation pool rather than independent photoreceptors. PMID:7320894

Two daily smoke maxima in eighteenth century London air

NASA Astrophysics Data System (ADS)

Harrison, R. Giles

Varied electrostatics experiments followed Benjamin Franklin's pioneering atmospheric investigations. In Knightsbridge, Central London, John Read (1726-1814) installed a sensing rod in the upper part of his house and, using a pith ball electrometer and Franklin chimes, monitored atmospheric electricity from 1789 to 1791. Atmospheric electricity is sensitive to weather and smoke pollution. In calm weather conditions, Read observed two daily electrification maxima in moderate weather, around 9 am and 7 pm. This is likely to represent a double diurnal cycle in urban smoke. Before the motor car and steam railways, one source of the double maximum smoke pattern was the daily routine of fire lighting for domestic heating.

LMFBR fuel assembly design for HCDA fuel dispersal

DOEpatents

Lacko, Robert E.; Tilbrook, Roger W.

1984-01-01

A fuel assembly for a liquid metal fast breeder reactor having an upper axial blanket region disposed in a plurality of zones within the fuel assembly. The characterization of a zone is dependent on the height of the axial blanket region with respect to the active fuel region. The net effect of having a plurality of zones is to establish a dispersal flow path for the molten materials resulting during a core meltdown accident. Upward flowing molten material can escape from the core region and/or fuel assembly without solidifying on the surface of fuel rods due to the heat sink represented by blanket region pellets.

Retinal Degeneration in a Rodent Model of Smith-Lemli-Opitz Syndrome

PubMed Central

Fliesler, Steven J.; Peachey, Neal S.; Richards, Michael J.; Nagel, Barbara A.; Vaughan, Dana K.

2010-01-01

Objective To assess the electrophysiologic, histologic, and biochemical features of an animal model of Smith-Lemli-Opitz syndrome (SLOS). Methods Sprague-Dawley rats were treated with AY9944, a selective inhibitor of 3β-hydroxysterol-Δ7-reductase (the affected enzyme in SLOS). Dark- and light-adapted electroretinograms were obtained from treated and control animals. From each animal, 1 retina was analyzed by microscopy, and the contralateral retina plus serum samples were analyzed for sterol composition. The main outcome measures were rod and cone electroretinographic amplitudes and implicit times, outer nuclear layer (ONL) thickness, rod outer segment length, pyknotic ONL nucleus counts, and the 7-dehydrocholesterol/ cholesterol mole ratio in the retina and serum. Results By 10 weeks’ postnatal age, rod and cone electroretinographic wave amplitudes in AY9944-treated animals were significantly reduced and implicit times were significantly increased relative to controls. Maximal rod photoresponse and gain values were reduced approximately 2-fold in treated animals relative to controls. The ONL thickness and average rod outer segment length were reduced by approximately 18% and 33%, respectively, and ONL pyknotic nucleus counts were approximately 4.5-fold greater in treated animals relative to controls. The retinal pigment epithelium of treated animals contained massive amounts of membranous/lipid inclusions not routinely observed in controls. The 7-dehydrocholesterol/cholesterol mole ratios in treated retinas and serum samples were approximately 5:1 and 9:1, respectively, whereas the ratios in control tissues were essentially zero. Conclusions This rodent model exhibits the key biochemical hallmarks associated with SLOS and displays electrophysiologic deficits comparable to or greater than those observed in the human disease. Clinical Relevance These results predict retinal degeneration in patients with SLOS, particularly those with the more severe (type II) form of the disease, and may be more broadly relevant to other inborn errors of cholesterol biosynthesis. This animal model may also be of use in evaluating therapeutic treatments for SLOS and in understanding the slow phototransduction kinetics observed in patients with SLOS. PMID:15302661

CLIMATE CHANGE IN THE UPPER GREAT LAKES REGION: A WORKSHOP REPORT

EPA Science Inventory

This paper, "Coping With Climate Change", argues that adaptation is an important strategy for protecting human health, ecosystems, and economic activity as the climate changes. Adaptation is an essential component of any portfolio of actions that comprise U.S. climate change poli...

Bacterial flora of combat wounds from eastern Ukraine and time-specified changes of bacterial recovery during treatment in Ukrainian military hospital.

PubMed

Valentine, Kovalchuk P; Viacheslav, Kondratiuk M

2017-04-07

Microbiology of modern war wounds is unique for each military conflict. Climatic and geographical features of the theater of war, contemporary warfare as well as wound management affect the microbial flora of wounds. This study was designed to determine time-specific microbial flora of combat wounds of upper and lower extremities obtained during the war in eastern Ukraine. The patients enrolled in study had combat wounds of upper or lower extremities which were treated in the Military Medical Clinical Center of Central Region. The wounds were swab-cultured and measured at each surgical debridement. The recovered microorganisms were identified and their antimicrobial resistance profiles were evaluated by disc diffusion method. Forty-nine patients with battle-field wounds were enrolled in the study from July to November 2014; all patients were male with a mean Injury Severity Score and arrival APACHE II scores of 16.2 ± 10.7 and 7.4 ± 4.2 respectively. Among 128 swab cultures, 100 swab cultures were positive. Swab cultures were obtained from 57 wounds of 49 patients. The results of the test showed that 87.7% of all positive swab cultures contained a single-organism while the rest of the swab-culture results showed polymicrobial growth. Among the isolated microorganisms 65% (76 strains) were Gram-negative rods, 22.2% (26 strains) of Gram-positive cocci, followed by Gram-positive rods (12.8%, 15 strains). We found that epidemiology of wound infection changes with the time after injury. The most common bacterial isolates cultured during the first week were Gram-positive microbes with low pathogenicity. The number of Gram-negative rods increased during the wound healing process. The incidence of Gram-positive microorganisms' growth fell after the first week and increased after third week. During wound healing, bacterial microflora of wounds changes with increasing number of Gram-negative rods with predominance of Acinetobacter species. Predominant microorganisms in positive swab-cultures after first week were nonfermentative Gram-negative bacilli (68% of swab-cultures), which in 53% of the swab-cultures belonged to the genus Acinetobacter, and in 15% to the genus Pseudomonas. The incidence of polymicrobial wound cultures increased from first week to second post-injury week. The most frequent microbial mixture were Acinetobacter baumannii with Enterobacteriaceae or other nonfermentative Gram negative rods with Enterococcus spp. We observed bacteria recovery from wounds during proliferation phase. These wounds had no pure inflammation signs and were free of devitalized tissues. Any wound is at some risk of becoming infected. In the event of infection, a wound fails to heal, treatment costs rise, and general wound management practices become more resource demanding. Determining the microorganisms which colonize battle wounds and cause wound infection is paramount. This information can help to treat battle wound infections or even changes infection control strategies. The fact of shifting in wound microbiology in the favor of bacteria responsible for healthcare-associated infections support to the proposition that these changes are nosocomially related [4, 14]. For Ukrainian military medicine this study is the first time-specified assessment of battle wound colonization from the World War II.

A novel four-bar linkage prosthetic knee based on magnetorheological effect: principle, structure, simulation and control

NASA Astrophysics Data System (ADS)

Xu, Lei; Wang, Dai-Hua; Fu, Qiang; Yuan, Gang; Hu, Lei-Zi

2016-11-01

In this paper, the principle and structure of the four-bar linkage prosthetic knee based on the magnetorheological effect (FLPKME) are proposed and realized by individually integrating the upper and lower link rods of the four-bar linkage with the piston rod and the outer cylinder of the magnetorheological (MR) damper. The integrated MR damper, in which the MR fluid is operated in the shear mode, has a double-ended structure. The prototype of the FLPKME is designed and fabricated. Utilizing the developed FLPKME, the lower limb prosthesis is developed, modeled, and simulated. On these bases, the control algorithm for the FLPKME is developed. A test platform for the FLPKME is developed and the performance of the FLPKME with seven constant currents and controlled currents by the control algorithm developed in this paper are experimentally tested. The results show that the FLPKME with a constant current of 1.6 A possesses the basic stable gait, and the FLPKME with the controlled currents by the control algorithm developed in this paper is able to track the motions well and to imitate the natural motions of a healthy human knee joint.

Preliminary Weight Savings Estimate for a Commercial Transport Wing Using Rod-Stiffened Stitched Composite Technology

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.

2015-01-01

A structural concept called pultruded rod stitched efficient unitized structure (PRSEUS) was developed by the Boeing Company to address the complex structural design aspects associated with a pressurized hybrid wing body (HWB) aircraft configuration. While PRSEUS was an enabling technology for the pressurized HWB structure, limited investigation of PRSEUS for other aircraft structures, such as circular fuselages and wings, has been done. Therefore, a study was undertaken to investigate the potential weight savings afforded by using the PRSEUS concept for a commercial transport wing. The study applied PRSEUS to the Advanced Subsonic Technology (AST) Program composite semi-span test article, which was sized using three load cases. The initial PRSEUS design was developed by matching cross-sectional stiffnesses for each stringer/skin combination within the wing covers, then the design was modified to ensure that the PRSEUS design satisfied the design criteria. It was found that the PRSEUS wing design exhibited weight savings over the blade-stiffened composite AST Program wing of nearly 9%, and a weight savings of 49% and 29% for the lower and upper covers, respectively, compared to an equivalent metallic wing.

VICTORIA-92 pretest analyses of PHEBUS-FPT0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bixler, N.E.; Erickson, C.M.

FPT0 is the first of six tests that are scheduled to be conducted in an experimental reactor in Cadarache, France. The test apparatus consists of an in-pile fuel bundle, an upper plenum, a hot leg, a steam generator, a cold leg, and a small containment. Thus, the test is integral in the sense that it attempts to simulate all of the processes that would be operative in a severe nuclear accident. In FPT0, the fuel will be trace irradiated; in subsequent tests high burn-up fuel will be used. This report discusses separate pretest analyses of the FPT0 fuel bundle andmore » primary circuit have been conducted using the USNRC`s source term code, VICTORIA-92. Predictions for release of fission product, control rod, and structural elements from the test section are compared with those given by CORSOR-M. In general, the releases predicted by VICTORIA-92 occur earlier than those predicted by CORSOR-M. The other notable difference is that U release is predicted to be on a par with that of the control rod elements; CORSOR-M predicts U release to be about 2 orders of magnitude greater.« less

Nonlinear finite element modeling of vibration control of plane rod-type structural members with integrated piezoelectric patches

NASA Astrophysics Data System (ADS)

Chróścielewski, Jacek; Schmidt, Rüdiger; Eremeyev, Victor A.

2018-05-01

This paper addresses modeling and finite element analysis of the transient large-amplitude vibration response of thin rod-type structures (e.g., plane curved beams, arches, ring shells) and its control by integrated piezoelectric layers. A geometrically nonlinear finite beam element for the analysis of piezolaminated structures is developed that is based on the Bernoulli hypothesis and the assumptions of small strains and finite rotations of the normal. The finite element model can be applied to static, stability, and transient analysis of smart structures consisting of a master structure and integrated piezoelectric actuator layers or patches attached to the upper and lower surfaces. Two problems are studied extensively: (i) FE analyses of a clamped semicircular ring shell that has been used as a benchmark problem for linear vibration control in several recent papers are critically reviewed and extended to account for the effects of structural nonlinearity and (ii) a smart circular arch subjected to a hydrostatic pressure load is investigated statically and dynamically in order to study the shift of bifurcation and limit points, eigenfrequencies, and eigenvectors, as well as vibration control for loading conditions which may lead to dynamic loss of stability.

Terminator assembly for a floating structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiu, H.; Hall, J.E.

1987-10-20

A terminator assembly is described for use in mooring a floating surface to the floor of a body of water. The floating structure has has an upper support and a lower support, comprising: a hawsepipe extending downwardly from adjacent the upper support and supported by the lower support, a tension member extending downwardly from adjacent the upper support through the hawsepipe and the lower support. The tension member has a lower end adapted for connection to the floor of the body of water. Locking means connected to an upper portion of the tension member for maintaining the tension member inmore » tension by acting upon an upper portion of the hawsepipe without transferring primary tension load forces to the upper support.« less

Influence of the coating process on the tribological conditions during cold forging with a MoS2 based lubricant

NASA Astrophysics Data System (ADS)

Lorenz, Robby; Hagenah, Hinnerk; Merklein, Marion

2018-05-01

Cold forging processes such as forward rod extrusion can be used to produce high quality components like connection rods, shafts and gears. The main advantages of these extruded components are sufficient surface quality, work hardening, compressive residual stresses and fatigue strength. Since one technical disadvantage of extruded components lies in the achievable tolerance classes, the improvement of these should be of crucial importance. For instance, the attainable workpiece accuracy and component quality can be influenced by adapting the tribological system in such a way that the resulting friction is specifically controlled in order to improve component forming. Lubricant modification is one practical way of adapting the tribological system to the requirements of the forming process. An industrial established and highly efficient lubricant system is the application of a zinc-phosphate conversion layer with a molybdenum disulfide-based lubricant. While offering many advantages, its tribological conditions seem to depend strongly on the layer weight and the application strategy. These parameters and the respective interdependencies have not been sufficiently investigated yet. In order to examine this, the tribological conditions depending on the layer weight are analyzed in greater detail using the Ring-Compression-Test (RCT). This tribometer provides a comparative representation of the forming conditions during cold forging. Furthermore, a potential dependency between the tribological conditions and two different coating techniques is analyzed. The latter are represented by the industrial standards dipping and dip-drumming.

Powder Keg on the Upper Missouri: Sources of Blackfeet Hostility, 1730-1810.

ERIC Educational Resources Information Center

Judy, Mark A.

1987-01-01

Evaluates reasons why Blackfeet Indians were bitterly hostile toward white fur traders in the upper Missouri River basin during the early 1800s. Explains causes of internal tribal turmoil including rapid adaptation of horses to tribal culture, devastating effects of disease, and guns disrupting the balance of power among tribes. (JHZ)

Participant perceptions of use of CyWee Z as adjunct to rehabilitation of upper-limb function following stroke.

PubMed

Hale, Leigh A; Satherley, Jessica A; McMillan, Nicole J; Milosavljevic, Stephan; Hijmans, Juha M; King, Marcus J

2012-01-01

This article reports on the perceptions of 14 adults with chronic stroke who participated in a pilot study to determine the utility, acceptability, and potential efficacy of using an adapted CyWee Z handheld game controller to play a variety of computer games aimed at improving upper-limb function. Four qualitative in-depth interviews and two focus groups explored participant perceptions. Data were thematically analyzed with the general inductive approach. Participants enjoyed playing the computer games with the technology. The perceived benefits included improved upper-limb function, concentration, and balance; however, six participants reported shoulder and/or arm pain or discomfort, which presented while they were engaged in play but appeared to ease during rest. Participants suggested changes to the games and provided opinions on the use of computer games in rehabilitation. Using an adapted CyWee Z controller and computer games in upper-limb rehabilitation for people with chronic stroke is an acceptable and potentially beneficial adjunct to rehabilitation. The development of shoulder pain was a negative side effect for some participants and requires further investigation.

Robust adaptive sliding mode control for uncertain systems with unknown time-varying delay input.

PubMed

Benamor, Anouar; Messaoud, Hassani

2018-05-02

This article focuses on robust adaptive sliding mode control law for uncertain discrete systems with unknown time-varying delay input, where the uncertainty is assumed unknown. The main results of this paper are divided into three phases. In the first phase, we propose a new sliding surface is derived within the Linear Matrix Inequalities (LMIs). In the second phase, using the new sliding surface, the novel Robust Sliding Mode Control (RSMC) is proposed where the upper bound of uncertainty is supposed known. Finally, the novel approach of Robust Adaptive Sliding ModeControl (RASMC) has been defined for this type of systems, where the upper limit of uncertainty which is assumed unknown. In this new approach, we have estimate the upper limit of uncertainties and we have determined the control law based on a sliding surface that will converge to zero. This novel control laws are been validated in simulation on an uncertain numerical system with good results and comparative study. This efficiency is emphasized through the application of the new controls on the two physical systems which are the process trainer PT326 and hydraulic system two tanks. Published by Elsevier Ltd.

Diverter/bop system and method for a bottom supported offshore drilling rig

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roche, J.R.; Alexander, G.G.; Carbaugh, W.L.

1986-07-01

A system is described adapted for alternative use as a diverter or a blowout preventer for a bottom supported drilling rig and adapted for connection to a permanent housing attached to rig structural members beneath a drilling rig rotary table, the permanent housing having an outlet connectable to a rig fluid system flow line. The system consists of: a fluid flow controller having a controller housing with a lower cylindrical opening and an upper cylindrical opening and a vertical path therebetween and a first outlet passage and a second outlet passage provided in its wall, a packing element disposed withinmore » the controller housing, and annular piston means adapted for moving from a first position to a second position, whereby in the first position the piston means wall prevents interior fluid from communicating with the outlet passages in the controller housing wall and in the second position the piston means wall allows fluid communication of interior fluid with the outlet passages and urges the annular packing element to close about an object extending through the bore of the controller housing or to close the vertical flow path through through the controller housing in the absence of any object in the vertical flow path, means for connecting a vent line to the outlet passage provided in the controller housing wall, a lower telescoping spool having a lower joining means at its lower end for joining alternatively to structural casing or to a mandrel connected to a conductor string cemented within the structural casing and an upper connection means at its upper end for connection to the lower cylindrical opening of the fluid flow controller, and an upper telescoping spool having a lower connection means for connection to the upper cylindrical opening of the fluid flow controller.« less

Lateral mass screw-rod fixation of the cervical spine: a prospective clinical series with 1-year follow-up.

PubMed

Deen, H Gordon; Birch, Barry D; Wharen, Robert E; Reimer, Ronald

2003-01-01

Lateral mass plating has become the technique of choice for posterior cervical fixation. Although these systems are safe and reliable, they can be difficult to use in patients with abnormal cervical anatomy; screw placement can be compromised by the fixed hole spacing of the plate; screw back-out and other forms of implant failure can occur; and extension across the cervicothoracic junction can be problematic. To report a series of patients undergoing posterior cervical stabilization with a polyaxial screw-rod construct and to investigate whether this new system offers any advantages over existing methods of fixation. A prospective study evaluating clinical and radiographic parameters in a consecutive series of patients treated with this technique. There were 21 patients in the study group. The surgical indication was cervical spondylosis in 14, trauma in 2, postsurgical kyphosis in 2 and 1 case each of congenital cervicothoracic stenosis, C7-T1 pseudarthrosis and basilar invagination with brainstem compression. Clinical indicators included age, gender, neurologic status, surgical indication and number of levels stabilized. Note was made of whether laminectomy and concomitant anterior reconstructive surgery were performed. Radiographic indicators included early postoperative computed tomography (CT) scan to check for screw placement and plain radiographs at subsequent visits. The participants in this study underwent posterior cervical stabilization using lateral mass screw-rod fixation. Clinical and radiographic assessment was carried out immediately after surgery, and 3, 6 and 12 months after surgery. One-year follow-up was obtained in all cases. A total of 212 screws were implanted in 21 patients. Fixation was carried out over an average of 5.5 spinal segments (range, 2 to 11). The system was successfully implanted in all patients despite the presence of coronal and sagittal plane deformities and/or lateral mass abnormalities in the majority of cases. This system allowed for screw placement in the occiput, C1 lateral mass, C2 pars, C3-C7 lateral masses and upper thoracic pedicles. Early postoperative CT scanning confirmed satisfactory screw placement in all cases. Three patients experienced transient single-level radiculopathy, for an incidence of 1.4% per screw placed. Two patients developed wound seromas requiring evacuation. There were no infections or other wound healing problems. There were no examples of cord or vertebral artery injury, cerebrospinal fluid leak, screw malposition or back-out, loss of alignment or implant failure. When compared with plating techniques, screw-rod fixation appeared to offer several advantages. First, unlike plates, rods proved to be amenable to multiplanar contouring, which is often needed for deformities associated with cervical spondylosis. Second, lateral mass screw placement was more precise because it was not constrained by the hole spacing of the plate. Third, screw back-out and other types of implant failure were not seen. Fourth, the screw-rod system was more easily extended to the occiput and across the cervicothoracic junction. Fifth, the screw-rod system permitted the application of compression, distraction and reduction forces within the construct, to a greater extent than plate systems. The incidence of postoperative radiculopathy was similar to that seen with plate systems. These data indicate that posterior cervical stabilization with polyaxial screw-rod fixation is a safe, straightforward technique that appears to offer some advantages over existing methods of fixation. Results appear to be durable at 1-year follow-up. Benefits are more significant with longer constructs, especially those extending to the occiput or crossing the cervicothoracic junction.

Stress analysis in a pedicle screw fixation system with flexible rods in the lumbar spine.

PubMed

Kim, Kyungsoo; Park, Won Man; Kim, Yoon Hyuk; Lee, SuKyoung

2010-01-01

Breakage of screws has been one of the most common complications in spinal fixation systems. However, no studies have examined the breakage risk of pedicle screw fixation systems that use flexible rods, even though flexible rods are currently being used for dynamic stabilization. In this study, the risk of breakage of screws for the rods with various flexibilities in pedicle screw fixation systems is investigated by calculating the von Mises stress as a breakage risk factor using finite element analysis. Three-dimensional finite element models of the lumbar spine with posterior one-level spinal fixations at L4-L5 using four types of rod (a straight rod, a 4 mm spring rod, a 3 mm spring rod, and a 2 mm spring rod) were developed. The von Mises stresses in both the pedicle screws and the rods were analysed under flexion, extension, lateral bending, and torsion moments of 10 Nm with a follower load of 400 N. The maximum von Mises stress, which was concentrated on the neck region of the pedicle screw, decreased as the flexibility of the rod increased. However, the ratio of the maximum stress in the rod to the yield stress increased substantially when a highly flexible rod was used. Thus, the level of rod flexibility should be considered carefully when using flexible rods for dynamic stabilization because the intersegmental motion facilitated by the flexible rod results in rod breakage.

Characterization and application of shape-changing panels with embedded rubber muscle actuators

NASA Astrophysics Data System (ADS)

Peel, Larry D.; Molina, Enrique, Jr.; Baur, Jeffery W.; Justice, Ryan S.

2013-09-01

Cylindrical soft actuators efficiently convert fluid pressure into mechanical energy and thus offer excellent force-to-weight ratios while behaving similar to biological muscle. McKibben-like rubber muscle actuators (RMAs) were embedded into neat elastomer and act as shape-changing panels. The effect of actuator spacing and modeling methods on the performance of these panels was investigated. Simulations from nonlinear finite element models were compared with results from test panels containing four RMAs that were spaced 0, 1/2, 1, and 1.3 RMA diameters apart. Nonlinear ‘laminated plate’ and ‘rod & plate’ finite element (FE) models of individual (non-embedded) RMAs and panels with embedded RMAs were developed. Due to model complexity and resource limitations, several simplified 2D and 3D FE model types, including a 3D ‘Unit Cell’ were created. After subtracting the ‘activation pressure’ needed to initiate contraction, all the models for the individual actuators produced forces consistent with experimental values, but only the more resource-intensive rod & plate models replicated fiber/braid re-orientation and produced more realistic values for actuator contraction. For panel models, the Full 3D rod & plate model appeared to be the most accurate for panel contraction and force, but was not completed for all configurations due to resource limitations. Most embedded panel FE models produced maximum panel actuator force and maximum contraction when the embedded actuators are spaced between 1/2 and 1 diameter apart. Seven panels with embedded RMAs were experimentally fabricated and tested. Panel tests confirmed that maximum or optimal performance occurs when the RMAs are spaced between 1/2 and 1 diameter apart. The tested actuator force was fairly constant in this range, suggesting that minor design or manufacturing differences may not significantly affect panel performance. However, the amount of axial force and contraction decreases significantly at greater than optimal spacing. This multi-faceted work provides useful design, simulation fabrication, and test characteristics for shape-adaptive panels. Bending panels were demonstrated but not modeled. Developers of future shape-adaptive air vehicles have been provided with additional simulation and design tools.

DIFFUSION PUMP

DOEpatents

Levenson, L.

1963-09-01

A high-vacuum diffusion pump is described, featuring a novel housing geometry for enhancing pumping speed. An upright, cylindrical lower housing portion is surmounted by a concentric, upright, cylindrical upper housing portion of substantially larger diameter; an uppermost nozzle, disposed concentrically within the upper portion, is adapted to eject downwardly a conical sheet of liquid outwardly to impinge upon the uppermost extremity of the interior wall of the lower portion. Preferably this nozzle is mounted upon a pedestal rising coaxially from within the lower portion and projecting up into said upper portion. (AEC)

Modeling and simulation performance of sucker rod beam pump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aditsania, Annisa, E-mail: annisaaditsania@gmail.com; Rahmawati, Silvy Dewi, E-mail: silvyarahmawati@gmail.com; Sukarno, Pudjo, E-mail: psukarno@gmail.com

2015-09-30

Artificial lift is a mechanism to lift hydrocarbon, generally petroleum, from a well to surface. This is used in the case that the natural pressure from the reservoir has significantly decreased. Sucker rod beam pumping is a method of artificial lift. Sucker rod beam pump is modeled in this research as a function of geometry of the surface part, the size of sucker rod string, and fluid properties. Besides its length, sucker rod string also classified into tapered and un-tapered. At the beginning of this research, for easy modeling, the sucker rod string was assumed as un-tapered. The assumption provedmore » non-realistic to use. Therefore, the tapered sucker rod string modeling needs building. The numerical solution of this sucker rod beam pump model is computed using finite difference method. The numerical result shows that the peak of polished rod load for sucker rod beam pump unit C-456-D-256-120, for non-tapered sucker rod string is 38504.2 lb, while for tapered rod string is 25723.3 lb. For that reason, to avoid the sucker rod string breaks due to the overload, the use of tapered sucker rod beam string is suggested in this research.« less

Silicone sensing phase for detection of aromatic hydrocarbons in water employing near-infrared spectroscopy.

PubMed

Albuquerque, Jackson S; Pimentel, M Fernanda; Silva, Valdinete L; Raimundo, Ivo M; Rohwedder, Jarbas J R; Pasquini, Celio

2005-01-01

The use of silicone for detection of aromatic hydrocarbons in water using near-infrared spectroscopy is proposed. A sensing phase of poly(dimethylsiloxane) (PDMS) was prepared, and a rod of this material was adapted to a transflectance probe for measurements from 850 to 1800 nm. Deionized water samples contaminated separately with known amounts of benzene, toluene, ethylbenzene, and m-xylene were used for evaluation of the PDMS sensing phase, and measurements were made in a closed reactor with constant stirring. Equilibrium states were obtained after 90, 180, 360, and 405 min for benzene, toluene, ethylbenzene, and m-xylene, respectively. The PDMS sensing phase showed a reversible response, presenting linear response ranges up to 360, 290, 100, and 80 mg L(-1), with detection limits of 8.0, 7.0, 2.6, and 3.0 mg L(-1) for benzene, toluene, ethylbenzene, and m-xylene, respectively. Reference spectra obtained with different rods showed a relative standard deviation of 0.5%, indicating repeatability in the sensing phase preparation. A relative standard deviation of 6.7% was obtained for measurements performed with six different rods, using a 52 mg L(-1) toluene aqueous solution. The sensing phase was evaluated for identification of sources of contamination of water in simulated studies, employing Brazilian gasoline type A (without ethanol), gasoline type C (with 25% of anhydrous ethanol), and diesel fuel. Principal component analysis was able to classify the water in distinct groups, contaminated by gasoline A, gasoline C, or diesel fuel.

A five-primary photostimulator suitable for studying intrinsically photosensitive retinal ganglion cell functions in humans

PubMed Central

Cao, Dingcai; Nicandro, Nathaniel; Barrionuevo, Pablo A.

2015-01-01

Intrinsically photosensitive retinal ganglion cells (ipRGCs) can respond to light directly through self-contained photopigment, melanopsin. IpRGCs also receive synaptic inputs from rods and cones. Thus, studying ipRGC functions requires a novel photostimulating method that can account for all of the photoreceptor inputs. Here, we introduced an inexpensive LED-based five-primary photostimulator that can control the excitations of rods, S-, M-, L-cones, and melanopsin-containing ipRGCs in humans at constant background photoreceptor excitation levels, a critical requirement for studying the adaptation behavior of ipRGCs with rod, cone, or melanopsin input. We described the theory and technical aspects (including optics, electronics, software, and calibration) of the five-primary photostimulator. Then we presented two preliminary studies using the photostimulator we have implemented to measure melanopsin-mediated pupil responses and temporal contrast sensitivity function (TCSF). The results showed that the S-cone input to pupil responses was antagonistic to the L-, M- or melanopsin inputs, consistent with an S-OFF and (L + M)-ON response property of primate ipRGCs (Dacey et al., 2005). In addition, the melanopsin-mediated TCSF had a distinctive pattern compared with L + M or S-cone mediated TCSF. Other than controlling individual photoreceptor excitation independently, the five-primary photostimulator has the flexibility in presenting stimuli modulating any combination of photoreceptor excitations, which allows researchers to study the mechanisms by which ipRGCs combine various photoreceptor inputs. PMID:25624466

Investigation of retinal microstructure in healthy eyes and dry age-related macular degeneration using a combined AO-OCT-SLO system

NASA Astrophysics Data System (ADS)

Wells-Gray, Elaine M.; Choi, Stacey S.; Ohr, Matthew; Cebulla, Colleen M.; Doble, Nathan

2017-02-01

Combined adaptive optics (AO) optical coherence tomography (OCT) scanning laser ophthalmoscopy (SLO) imaging allows simultaneous en face and cross sectional views of the retina. We describe improvements to our AO-OCT-SLO system and highlight its resolution capability and clinical utility by presenting results from 3 control and 4 dry agerelated macular degeneration (AMD) subjects. From a group of subjects with healthy eyes, OCT A-scans were grouped as originating from cones or rods and were averaged. The resulting reflectance profiles were then used to identify the location of cone and rod segments. Results for rods and cones were compared, with the focus on inner segment (IS) and outer segment (OS) structures and where these cells embed into the retinal pigment epithelium (RPE). In the AMD patients, cone IS and OS lengths were measured over and around drusen for two retinal regions (fovea-2° and 2°-4°), and those results were correlated to drusen height. For the fovea-2° region, the drusen height that caused statistically significant shortening of cone ISL and OSL compared to the unaffected adjacent area were 40 μm and 50 μm respectively (p = 0.009, and p < 0.001, respectively). For the 2°-4° region, the equivalent drusen heights that caused significant shortening of segment length were 60 μm for IS (p = 0.017) and 80 μm for OS (p < 0.001)

Manure and residue inputs maintained SOC in conservation production systems in the Upper Midwest

USDA-ARS?s Scientific Manuscript database

Conservation production systems are needed in the upper Midwest to slow down soil and nutrient loss through tillage-induced erosion. However, due to the cool, wet climate, producers are reluctant to adapt no-till strategies. With focus on strip-tillage (ST) and a diverse four-year crop rotation (4y...

Complications of growth-sparing surgery in early onset scoliosis.

PubMed

Akbarnia, Behrooz A; Emans, John B

2010-12-01

Review of available literature, authors' opinion. To describe complications associated with growth-sparing surgical treatment of early onset scoliosis (EOS). EOS has many potential etiologies and is often associated with thoracic insufficiency syndrome. The growth of the spine, thorax, and lungs are interrelated, and severe EOS typically involves disturbance of the normal development of all 3. Severe EOS may be treated during growth with surgical techniques, intended to preserve growth while controlling deformity, the most common of which are spinal "growing rods" (GR) or "vertical expandable prosthetic titanium rib" (VEPTR). Although presently popular, there is minimal long-term data on the outcome of growth-sparing surgical techniques on EOS. Review. Potential adverse outcomes of GR or VEPTR treatment of EOS include failure to prevent progressive deformity or thoracic insufficiency syndrome, an unacceptably short or stiff spine or deformed thorax, increased family burden of care, and potentially negative psychological consequences from repeated surgical interventions. Neither technique reliably controls all deformity over the entirety of growth period. Infections are common to both GR and VEPTR. Rod breakage and spontaneous premature spinal fusion beneath rods are troublesome complications in GR, whereas drift of rib attachments and chest wall scarring are anticipated complications in VEPTR treatment. Indications for GR and VEPTR overlap, but thoracogenic scoliosis and severe upper thoracic kyphosis are best treated by VEPTR and GR, respectively. Surgeons planning treatment of EOS should anticipate the many complications common to growth-sparing surgery, share their knowledge with families, and use complications as one factor in the complex decision as to when and whether to initiate the repetitive surgeries associated with GR or VEPTR in the treatment of severe EOS.

Adaptive steganography

NASA Astrophysics Data System (ADS)

Chandramouli, Rajarathnam; Li, Grace; Memon, Nasir D.

2002-04-01

Steganalysis techniques attempt to differentiate between stego-objects and cover-objects. In recent work we developed an explicit analytic upper bound for the steganographic capacity of LSB based steganographic techniques for a given false probability of detection. In this paper we look at adaptive steganographic techniques. Adaptive steganographic techniques take explicit steps to escape detection. We explore different techniques that can be used to adapt message embedding to the image content or to a known steganalysis technique. We investigate the advantages of adaptive steganography within an analytical framework. We also give experimental results with a state-of-the-art steganalysis technique demonstrating that adaptive embedding results in a significant number of bits embedded without detection.

Retinal instrument

DOEpatents

Britton, Charles L; D& #x27; Urso, Brian R; Chaum, Edward; Simpson, John T; Baba, Justin S; Ericson, M. Nance; Warmack, Robert J

2013-04-23

In one embodiment, the present invention provides a method of removing scar tissue from an eye that includes inserting a device including an array of micro-rods into an eye, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature; contacting a scar tissue with the array of micro-rods; and removing the array of micro-rods and the scar tissue from the eye. In another embodiment, the present invention provides a medical device for engaging a tissue including and an array of glass micro-rods, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature opposite a base of the array of glass micro-rods that is connected to the cannula, wherein the sharp feature of the at least one micro-rod is angled from a plane that is normal to a face of the base of the array of glass micro-rods.

Flexible non-fusion scoliosis correction systems reduce intervertebral rotation less than rigid implants and allow growth of the spine: a finite element analysis of different features of orthobiom™

PubMed Central

Zander, T.; Burra, N. K.; Bergmann, G.

2007-01-01

The orthobiom™ non-fusion scoliosis correction system consists of two longitudinal rods, polyaxial pedicle screws, mobile and fixed connectors and a cross-connector. The mobile connectors can move along and around the rod, thus allowing length adaptation during growth. The aim of this study was to determine the effects of different features of this novel implant on intervertebral rotations, to calculate the movement of the mobile connectors along the rods for different loading cases and to compare the results with those of a rigid implant construct. A finite element analysis was performed using six versions (M1–M6) of a three-dimensional, nonlinear model of a spine ranging from T3 to L2. The models were loaded with pure moments of 7.5 N m in the three main anatomical planes. First, the validated intact model (M1) was studied. Then, the orthobiom™ implant system was inserted, bridging the segments between T4 and L1 (M2). The effect of pedicle screws only in every second vertebrae was investigated (M3). For comparison, three connection variations of screws and rods were investigated: (1) an implant with rigid screws and mobile connectors (M4), (2) an implant with non-locking polyaxial screws and fixed connectors (M5) and (3) a completely rigid implant construct (M6). For flexion, extension and lateral bending, intervertebral rotation was reduced at all implant levels due to the implants. A rigid implant construct (M6) and an implant with non-locking polyaxial screws and fixed connectors (M5) led to the strongest reduction of intervertebral rotation. The orthobiom™ non-fusion implant system (M2, M3) allowed much more intervertebral rotation than a rigid implant (M6). Differences in intervertebral rotations were small when polyaxial screws were placed at every second level only (M3) instead of at every level (M2). For axial rotation, intervertebral rotation was strongly reduced by a rigid implant construct (M6) and by an implant with rigid screws and mobile connectors (M4). For rotation, an implant with non-locking polyaxial screws (M2, M3, M5) led to nearly the same intervertebral rotations as in an intact spine without an implant (M1). The predicted maximum translation of the mobile connectors along the rod was 4.2 mm for extension, 3.1 mm for lateral bending, 1.6 mm for flexion and 0.8 mm for axial rotation. The movement of the connectors was highest for those closest to the ends of the rods. With rigid screws, the maximum translation was significantly reduced. This study, conducted under a load-controlled loading protocol, showed that intervertebral rotation was reduced much less by the non-fusion orthobiom™ system than by a rigid implant. The mobile connectors moved considerably along the rod when the spine was bent. It can be expected that the connectors also move along the rod as the adolescent grows, possibly leaving the discs intact until the patient is fully grown. PMID:17712575

Influence of implant rod curvature on sagittal correction of scoliosis deformity.

PubMed

Salmingo, Remel Alingalan; Tadano, Shigeru; Abe, Yuichiro; Ito, Manabu

2014-08-01

Deformation of in vivo-implanted rods could alter the scoliosis sagittal correction. To our knowledge, no previous authors have investigated the influence of implanted-rod deformation on the sagittal deformity correction during scoliosis surgery. To analyze the changes of the implant rod's angle of curvature during surgery and establish its influence on sagittal correction of scoliosis deformity. A retrospective analysis of the preoperative and postoperative implant rod geometry and angle of curvature was conducted. Twenty adolescent idiopathic scoliosis patients underwent surgery. Average age at the time of operation was 14 years. The preoperative and postoperative implant rod angle of curvature expressed in degrees was obtained for each patient. Two implant rods were attached to the concave and convex side of the spinal deformity. The preoperative implant rod geometry was measured before surgical implantation. The postoperative implant rod geometry after surgery was measured by computed tomography. The implant rod angle of curvature at the sagittal plane was obtained from the implant rod geometry. The angle of curvature between the implant rod extreme ends was measured before implantation and after surgery. The sagittal curvature between the corresponding spinal levels of healthy adolescents obtained by previous studies was compared with the implant rod angle of curvature to evaluate the sagittal curve correction. The difference between the postoperative implant rod angle of curvature and normal spine sagittal curvature of the corresponding instrumented level was used to evaluate over or under correction of the sagittal deformity. The implant rods at the concave side of deformity of all patients were significantly deformed after surgery. The average degree of rod deformation Δθ at the concave and convex sides was 15.8° and 1.6°, respectively. The average preoperative and postoperative implant rod angle of curvature at the concave side was 33.6° and 17.8°, respectively. The average preoperative and postoperative implant rod angle of curvature at the convex side was 25.5° and 23.9°, respectively. A significant relationship was found between the degree of rod deformation and preoperative implant rod angle of curvature (r=0.60, p<.005). The implant rods at the convex side of all patients did not have significant deformation. The results indicate that the postoperative sagittal outcome could be predicted from the initial rod shape. Changes in implant rod angle of curvature may lead to over- or undercorrection of the sagittal curve. Rod deformation at the concave side suggests that corrective forces acting on that side are greater than the convex side. Copyright © 2014 Elsevier Inc. All rights reserved.

Nuclear reactor remote disconnect control rod coupling indicator

DOEpatents

Vuckovich, Michael

1977-01-01

A coupling indicator for use with nuclear reactor control rod assemblies which have remotely disengageable couplings between the control rod and the control rod drive shaft. The coupling indicator indicates whether the control rod and the control rod drive shaft are engaged or disengaged. A resistive network, utilizing magnetic reed switches, senses the position of the control rod drive mechanism lead screw and the control rod position indicating tube, and the relative position of these two elements with respect to each other is compared to determine whether the coupling is engaged or disengaged.

Environmental Assessment Addressing the Emerald Breeze Resort, Santa Rosa Island, Fort Walton Beach, Florida

DTIC Science & Technology

2009-09-11

conditions in their upper part. Anaerobic soil conditions are conducive to the establishment of vegetation that is adapted for growth under oxygen...sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted to life in saturated soil...species adapted to dense commercial development and heavy vehicular traffic would be expected to move back into the area after development of the

The membrane current of single rod outer segments.

PubMed

Baylor, D A; Lamb, T D; Yau, K W

1979-03-01

1. Outer segments of individual rods in the retina of the toad, Bufo marinus, were drawn into a glass pipette to record the membrane current. 2. Light flashes evoked transient outward currents. The peak response amplitude was related to flash intensity by a Michaelis equation with half-saturating intensity about 1 photon mum-2. 3. The saturating response amplitude ranged up to 27 pA and corresponded closely to complete suppression of the steady inward current present in darkness. 4. For a given cell the saturating response amplitude varied linearly with the length of outer segment within the pipette. This is consistent with a uniform density of light-sensitive channels and negligible gradient of membrane potential along the outer segment. 5. Responses to bright flashes never showed the relaxation from an initial peak seen previously in intracellular voltage recordings, suggesting that the conductance change responsible for the relaxation does not occur in the outer segment. 6. Responses to local illumination of only the recorded outer segment were very similar to those obtained with diffuse light at the same intensity, indicating that peripheral rods made little contribution to the responses. 7. The spectral sensitivity of 'red' rods was consistent with a retinal1-based pigment with lambda max = 498 +/- 2 nm. 8. The kinetics of the response were consistent with four stages of delay affecting action of the internal transmitter. Responses were faster at the basal end of the outer segment than at the distal tip. 9. Background light reduced the sensitivity to a superposed dim test flash and shortened the time course of the response, indicating that adapting light modifies the kinetics and gain of the transduction mechanism within the outer segment. 10. Responses to dim lights exhibited pronounced fluctuations which are attributed in the succeeding paper (Baylor, Lamb & Yau, 1979) to the quantal nature of light.

Rip3 knockdown rescues photoreceptor cell death in blind pde6c zebrafish.

PubMed

Viringipurampeer, I A; Shan, X; Gregory-Evans, K; Zhang, J P; Mohammadi, Z; Gregory-Evans, C Y

2014-05-01

Achromatopsia is a progressive autosomal recessive retinal disease characterized by early loss of cone photoreceptors and later rod photoreceptor loss. In most cases, mutations have been identified in CNGA3, CNGB3, GNAT2, PDE6C or PDE6H genes. Owing to this genetic heterogeneity, mutation-independent therapeutic schemes aimed at preventing cone cell death are very attractive treatment strategies. In pde6c(w59) mutant zebrafish, cone photoreceptors expressed high levels of receptor-interacting protein kinase 1 (RIP1) and receptor-interacting protein kinase 3 (RIP3) kinases, key regulators of necroptotic cell death. In contrast, rod photoreceptor cells were alternatively immunopositive for caspase-3 indicating activation of caspase-dependent apoptosis in these cells. Morpholino gene knockdown of rip3 in pde6c(w59) embryos rescued the dying cone photoreceptors by inhibiting the formation of reactive oxygen species and by inhibiting second-order neuron remodelling in the inner retina. In rip3 morphant larvae, visual function was restored in the cones by upregulation of the rod phosphodiesterase genes (pde6a and pde6b), compensating for the lack of cone pde6c suggesting that cones are able to adapt to their local environment. Furthermore, we demonstrated through pharmacological inhibition of RIP1 and RIP3 activity that cone cell death was also delayed. Collectively, these results demonstrate that the underlying mechanism of cone cell death in the pde6c(w59) mutant retina is through necroptosis, whereas rod photoreceptor bystander death occurs through a caspase-dependent mechanism. This suggests that targeting the RIP kinase signalling pathway could be an effective therapeutic intervention in retinal degeneration patients. As bystander cell death is an important feature of many retinal diseases, combinatorial approaches targeting different cell death pathways may evolve as an important general principle in treatment.

cAMP controls rod photoreceptor sensitivity via multiple targets in the phototransduction cascade

PubMed Central

Astakhova, Luba A.; Samoiliuk, Evgeniia V.; Govardovskii, Victor I.

2012-01-01

In early studies, both cyclic AMP (cAMP) and cGMP were considered as potential secondary messengers regulating the conductivity of the vertebrate photoreceptor plasma membrane. Later discovery of the cGMP specificity of cyclic nucleotide–gated channels has shifted attention to cGMP as the only secondary messenger in the phototransduction cascade, and cAMP is not considered in modern schemes of phototransduction. Here, we report evidence that cAMP may also be involved in regulation of the phototransduction cascade. Using a suction pipette technique, we recorded light responses of isolated solitary rods from the frog retina in normal solution and in the medium containing 2 µM of adenylate cyclase activator forskolin. Under forskolin action, flash sensitivity rose more than twofold because of a retarded photoresponse turn-off. The same concentration of forskolin lead to a 2.5-fold increase in the rod outer segment cAMP, which is close to earlier reported natural day/night cAMP variations. Detailed analysis of cAMP action on the phototransduction cascade suggests that several targets are affected by cAMP increase: (a) basal dark phosphodiesterase (PDE) activity decreases; (b) at the same intensity of light background, steady background-induced PDE activity increases; (c) at light backgrounds, guanylate cyclase activity at a given fraction of open channels is reduced; and (d) the magnitude of the Ca2+ exchanger current rises 1.6-fold, which would correspond to a 1.6-fold elevation of [Ca2+]in. Analysis by a complete model of rod phototransduction suggests that an increase of [Ca2+]in might also explain effects (b) and (c). The mechanism(s) by which cAMP could regulate [Ca2+]in and PDE basal activity is unclear. We suggest that these regulations may have adaptive significance and improve the performance of the visual system when it switches between day and night light conditions. PMID:23008435

iRODS-Based Climate Data Services and Virtualization-as-a-Service in the NASA Center for Climate Simulation

NASA Astrophysics Data System (ADS)

Schnase, J. L.; Duffy, D. Q.; Tamkin, G. S.; Strong, S.; Ripley, D.; Gill, R.; Sinno, S. S.; Shen, Y.; Carriere, L. E.; Brieger, L.; Moore, R.; Rajasekar, A.; Schroeder, W.; Wan, M.

2011-12-01

Scientific data services are becoming an important part of the NASA Center for Climate Simulation's mission. Our technological response to this expanding role is built around the concept of specialized virtual climate data servers, repetitive cloud provisioning, image-based deployment and distribution, and virtualization-as-a-service. A virtual climate data server is an OAIS-compliant, iRODS-based data server designed to support a particular type of scientific data collection. iRODS is data grid middleware that provides policy-based control over collection-building, managing, querying, accessing, and preserving large scientific data sets. We have developed prototype vCDSs to manage NetCDF, HDF, and GeoTIF data products. We use RPM scripts to build vCDS images in our local computing environment, our local Virtual Machine Environment, NASA's Nebula Cloud Services, and Amazon's Elastic Compute Cloud. Once provisioned into these virtualized resources, multiple vCDSs can use iRODS's federation and realized object capabilities to create an integrated ecosystem of data servers that can scale and adapt to changing requirements. This approach enables platform- or software-as-a-service deployment of the vCDSs and allows the NCCS to offer virtualization-as-a-service, a capacity to respond in an agile way to new customer requests for data services, and a path for migrating existing services into the cloud. We have registered MODIS Atmosphere data products in a vCDS that contains 54 million registered files, 630TB of data, and over 300 million metadata values. We are now assembling IPCC AR5 data into a production vCDS that will provide the platform upon which NCCS's Earth System Grid (ESG) node publishes to the extended science community. In this talk, we describe our approach, experiences, lessons learned, and plans for the future.

Rod Monochromacy and the Coevolution of Cetacean Retinal Opsins

PubMed Central

Meredith, Robert W.; Gatesy, John; Emerling, Christopher A.; York, Vincent M.; Springer, Mark S.

2013-01-01

Cetaceans have a long history of commitment to a fully aquatic lifestyle that extends back to the Eocene. Extant species have evolved a spectacular array of adaptations in conjunction with their deployment into a diverse array of aquatic habitats. Sensory systems are among those that have experienced radical transformations in the evolutionary history of this clade. In the case of vision, previous studies have demonstrated important changes in the genes encoding rod opsin (RH1), short-wavelength sensitive opsin 1 (SWS1), and long-wavelength sensitive opsin (LWS) in selected cetaceans, but have not examined the full complement of opsin genes across the complete range of cetacean families. Here, we report protein-coding sequences for RH1 and both color opsin genes (SWS1, LWS) from representatives of all extant cetacean families. We examine competing hypotheses pertaining to the timing of blue shifts in RH1 relative to SWS1 inactivation in the early history of Cetacea, and we test the hypothesis that some cetaceans are rod monochomats. Molecular evolutionary analyses contradict the “coastal” hypothesis, wherein SWS1 was pseudogenized in the common ancestor of Cetacea, and instead suggest that RH1 was blue-shifted in the common ancestor of Cetacea before SWS1 was independently knocked out in baleen whales (Mysticeti) and in toothed whales (Odontoceti). Further, molecular evidence implies that LWS was inactivated convergently on at least five occasions in Cetacea: (1) Balaenidae (bowhead and right whales), (2) Balaenopteroidea (rorquals plus gray whale), (3) Mesoplodon bidens (Sowerby's beaked whale), (4) Physeter macrocephalus (giant sperm whale), and (5) Kogia breviceps (pygmy sperm whale). All of these cetaceans are known to dive to depths of at least 100 m where the underwater light field is dim and dominated by blue light. The knockout of both SWS1 and LWS in multiple cetacean lineages renders these taxa rod monochromats, a condition previously unknown among mammalian species. PMID:23637615

Design of a fuel element for a lead-cooled fast reactor

NASA Astrophysics Data System (ADS)

Sobolev, V.; Malambu, E.; Abderrahim, H. Aït

2009-03-01

The options of a lead-cooled fast reactor (LFR) of the fourth generation (GEN-IV) reactor with the electric power of 600 MW are investigated in the ELSY Project. The fuel selection, design and optimization are important steps of the project. Three types of fuel are considered as candidates: highly enriched Pu-U mixed oxide (MOX) fuel for the first core, the MOX containing between 2.5% and 5.0% of the minor actinides (MA) for next core and Pu-U-MA nitride fuel as an advanced option. Reference fuel rods with claddings made of T91 ferrite-martensitic steel and two alternative fuel assembly designs (one uses a closed hexagonal wrapper and the other is an open square variant without wrapper) have been assessed. This study focuses on the core variant with the closed hexagonal fuel assemblies. Based on the neutronic parameters provided by Monte-Carlo modeling with MCNP5 and ALEPH codes, simulations have been carried out to assess the long-term thermal-mechanical behaviour of the hottest fuel rods. A modified version of the fuel performance code FEMAXI-SCK-1, adapted for fast neutron spectrum, new fuels, cladding materials and coolant, was utilized for these calculations. The obtained results show that the fuel rods can withstand more than four effective full power years under the normal operation conditions without pellet-cladding mechanical interaction (PCMI). In a variant with solid fuel pellets, a mild PCMI can appear during the fifth year, however, it remains at an acceptable level up to the end of operation when the peak fuel pellet burnup ∼80 MW d kg-1 of heavy metal (HM) and the maximum clad damage of about 82 displacements per atom (dpa) are reached. Annular pellets permit to delay PCMI for about 1 year. Based on the results of this simulation, further steps are envisioned for the optimization of the fuel rod design, aiming at achieving the fuel burnup of 100 MW d kg-1 of HM.

Scanning laser densitometry and color perimetry demonstrate reduced photopigment density and sensitivity in two patients with retinal degeneration.

PubMed

Tornow, R P; Stilling, R; Zrenner, E

1999-10-01

To test the feasibility of scanning laser densitometry with a modified Rodenstock scanning laser ophthalmoscope (SLO) to measure the rod and cone photopigment distribution in patients with retinal diseases. Scanning laser densitometry was performed using a modified Rodenstock scanning laser ophthalmoscope. The distribution of the photopigments was calculated from dark adapted and bleached images taken with the 514 nm laser of the SLO. This wavelength is absorbed by rod and cone photopigments. Discrimination is possible due to their different spatial distribution. Additionally, to measure retinal sensitivity profiles, dark adapted two color static perimetry with a Tübinger manual perimeter was performed along the horizontal meridian with 1 degree spacing. A patient with retinitis pigmentosa had slightly reduced photopigment density within the central +/- 5 degrees but no detectable photopigment for eccentricities beyond 5 degrees. A patient with cone dystrophy had nearly normal pigment density beyond +/- 5 degrees, but considerably reduced photopigment density within the central +/- 5 degrees. Within the central +/- 5 degrees, the patient with retinitis pigmentosa had normal sensitivity for the red stimulus and reduced sensitivity for the green stimulus. There was no measurable function beyond 7 degrees. The patient with cone dystrophy had normal sensitivity for the green stimulus outside the foveal center and reduced sensitivity for the red stimulus at the foveal center. The results of color perimetry for this patient with a central scotoma were probably influenced by eccentric fixation. Scanning laser densitometry with a modified Rodenstock SLO is a useful method to assess the human photopigment distribution. Densitometry results were confirmed by dark adapted two color static perimetry. Photopigment distribution and retinal sensitivity profiles can be measured with high spatial resolution. This may help to measure exactly the temporal development of retinal diseases and to test the success of different therapeutic treatments. Both methods have limitations at the present state of development. However, some of these limitations can be overcome by further improving the instruments.

Ionic liquids-mediated interactions between nanorods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Zhou; Zhang, Fei; Huang, Jingsong

Surface forces mediated by room-temperature ionic liquids (RTILs) play an essential role in diverse applications including self-assembly, lubrication, and electrochemical energy storage. In this work, using molecular simulations we study the interactions between two nanorods immersed in model RTILs at rod-rod separations where both structural and double layer forces are important. The interaction force between neutral rods oscillates as the two rods approach each other, similar to the classical structural forces. Such oscillatory force originates from the density oscillation of RTILs near each rod and is affected by the packing constraints imposed by the neighboring rods. The oscillation period andmore » decay length of the oscillatory force are mainly dictated by the ion density distribution near isolated nanorods. When charges are introduced on the rods, the interaction force remains short-range and oscillatory, similar to the interactions between planar walls mediated by some protic RTILs reported earlier. Nevertheless, introducing net charges to the rods greatly changes the rod-rod interactions, e.g., by delaying the appearance of the first force trough and increasing the oscillation period and decay length of the interaction force. The oscillation period and decay length of the oscillatory force and free energy are commensurate with those of the space charge density near an isolated, charged rod. The free energy of rod-rod interactions reaches local minima (maxima) at rod-rod separations when the space charges near the two rods interfere constructively (destructively). Here, the insight on the short-range interactions between nanorods in RTILs helps guide the design of novel materials, e.g., crystalline ion gels based on rigid-rod polyanions and RTILs.« less

Ionic liquids-mediated interactions between nanorods

DOE PAGES

Yu, Zhou; Zhang, Fei; Huang, Jingsong; ...

2017-10-06

Surface forces mediated by room-temperature ionic liquids (RTILs) play an essential role in diverse applications including self-assembly, lubrication, and electrochemical energy storage. In this work, using molecular simulations we study the interactions between two nanorods immersed in model RTILs at rod-rod separations where both structural and double layer forces are important. The interaction force between neutral rods oscillates as the two rods approach each other, similar to the classical structural forces. Such oscillatory force originates from the density oscillation of RTILs near each rod and is affected by the packing constraints imposed by the neighboring rods. The oscillation period andmore » decay length of the oscillatory force are mainly dictated by the ion density distribution near isolated nanorods. When charges are introduced on the rods, the interaction force remains short-range and oscillatory, similar to the interactions between planar walls mediated by some protic RTILs reported earlier. Nevertheless, introducing net charges to the rods greatly changes the rod-rod interactions, e.g., by delaying the appearance of the first force trough and increasing the oscillation period and decay length of the interaction force. The oscillation period and decay length of the oscillatory force and free energy are commensurate with those of the space charge density near an isolated, charged rod. The free energy of rod-rod interactions reaches local minima (maxima) at rod-rod separations when the space charges near the two rods interfere constructively (destructively). Here, the insight on the short-range interactions between nanorods in RTILs helps guide the design of novel materials, e.g., crystalline ion gels based on rigid-rod polyanions and RTILs.« less

76 FR 77769 - North Finger Grazing Authorization Project, Malheur National Forest, Grant County, OR

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-14

... allotments within the North Finger Landscape. These allotments are within the Upper Deer Creek, Basin Creek... is to authorize grazing on all or portions of the North Finger landscape in such a manner that will... incorporating adaptive management strategies across the North Finger landscape. Adaptive Management is defined...

Walking boot assembly

NASA Technical Reports Server (NTRS)

Vykukal, H. C.; Chambers, A. B.; Stjohn, R. H. (Inventor)

1977-01-01

A walking boot assembly particularly suited for use with a positively pressurized spacesuit is presented. A bootie adapted to be secured to the foot of a wearer, an hermetically sealed boot for receiving the bootie having a walking sole, an inner sole, and an upper portion adapted to be attached to an ankle joint of a spacesuit, are also described.

Piezoelectric film load cell robot collision detector

DOEpatents

Lembke, J.R.

1988-03-15

A piezoelectric load cell which can be utilized for detecting collisions and obstruction of a robot arm end effector includes a force sensing element of metallized polyvinylidene fluoride (PVDF) film. The piezoelectric film sensing element and a resilient support pad are clamped in compression between upper and lower plates. The lower plate has a central recess in its upper face for supporting the support pad and sensing element, while the upper plate has a corresponding central projection formed on its lower face for bearing on the sensing element and support pad. The upper and lower plates are dowelled together for concentric alignment and screwed together. The upper and lower plates are also adapted for mounting between the robot arm wrist and end effector. 3 figs.

Piezoelectric film load cell robot collision detector

DOEpatents

Lembke, John R.

1989-04-18

A piezoelectric load cell which can be utilized for detecting collisions and obstruction of a robot arm end effector includes a force sensing element of metallized polyvinylidene fluoride (PVDF) film. The piezoelectric film sensing element and a resilient support pad are clamped in compression between upper and lower plates. The lower plate has a central recess in its upper face for supporting the support pad and sensing element, while the upper plate has a corresponding central projection formed on its lower face for bearing on the sensing element and support pad. The upper and lower plates are dowelled together for concentric alignment and screwed together. The upper and lower plates are also adapted for mounting between the robot arm wrist and end effector.

Piezoelectric film load cell robot collision detector

DOEpatents

Lembke, J.R.

1989-04-18

A piezoelectric load cell which can be utilized for detecting collisions and obstruction of a robot arm end effector includes a force sensing element of metallized polyvinylidene fluoride (PVDF) film. The piezoelectric film sensing element and a resilient support pad are clamped in compression between upper and lower plates. The lower plate has a central recess in its upper face for supporting the support pad and sensing element, while the upper plate has a corresponding central projection formed on its lower face for bearing on the sensing element and support pad. The upper and lower plates are doweled together for concentric alignment and screwed together. The upper and lower plates are also adapted for mounting between the robot arm wrist and end effector. 3 figs.

PBF (PER620) interior of Reactor Room. Camera facing south from ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PBF (PER-620) interior of Reactor Room. Camera facing south from stairway platform in southwest corner (similar to platform in view at left). Reactor was beneath water in circular tank. Fuel was stored in the canal north of it. Platform and apparatus at right is reactor bridge with control rod mechanisms and actuators. The entire apparatus swung over the reactor and pool during operations. Personnel in view are involved with decontamination and preparation of facility for demolition. Note rails near ceiling for crane; motor for rollup door at upper center of view. Date: March 2004. INEEL negative no. HD-41-3-2 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

Contrasting mechanisms of growth in two model rod-shaped bacteria

PubMed Central

Billaudeau, Cyrille; Chastanet, Arnaud; Yao, Zhizhong; Cornilleau, Charlène; Mirouze, Nicolas; Fromion, Vincent; Carballido-López, Rut

2017-01-01

How cells control their shape and size is a long-standing question in cell biology. Many rod-shaped bacteria elongate their sidewalls by the action of cell wall synthesizing machineries that are associated to actin-like MreB cortical patches. However, little is known about how elongation is regulated to enable varied growth rates and sizes. Here we use total internal reflection fluorescence microscopy and single-particle tracking to visualize MreB isoforms, as a proxy for cell wall synthesis, in Bacillus subtilis and Escherichia coli cells growing in different media and during nutrient upshift. We find that these two model organisms appear to use orthogonal strategies to adapt to growth regime variations: B. subtilis regulates MreB patch speed, while E. coli may mainly regulate the production capacity of MreB-associated cell wall machineries. We present numerical models that link MreB-mediated sidewall synthesis and cell elongation, and argue that the distinct regulatory mechanism employed might reflect the different cell wall integrity constraints in Gram-positive and Gram-negative bacteria. PMID:28589952

Basement of Structure, Main Power and Design Parameters of Mechanism of Removing Sections of Mechanized Sets of Knife Plane Installation

NASA Astrophysics Data System (ADS)

Sysoev, N. I.; Turuk, Yu V.; Kolesnichenko, I. Y.; Lugantsev, B. B.

2017-10-01

The reasons for the failure of the pitch stability of the knife-plane installation due to the action of extreme effort in the plane of the seam from the conveyor side on the mechanism of removing sections of mechanized sets are shown. The technique for determining this effort is presented. The constructions of the adaptive mechanisms of the removing sections of mechanized sets with the basements of catamaran type, in the constrictions of which elastic elements (rods) are used, are considered. The constructions of the mechanism of removing a section of the mechanized set with the basement of catamaran type in which the stock of the hydraulic jack is connected with the band loop through the movable rods intermediate basement with a link are worked out. The intermediate basement unloads the stock of the hydraulic jack of the moving installation from the side curving efforts, caused by the action of lateral forces in the plane of the seam on the conveyor side. It increases the reliability and efficiency of work of the knife plane mechanized complex.

Control rod drive

DOEpatents

Hawke, Basil C.

1986-01-01

A control rod drive uses gravitational forces to insert one or more control rods upwardly into a reactor core from beneath the reactor core under emergency conditions. The preferred control rod drive includes a vertically movable weight and a mechanism operatively associating the weight with the control rod so that downward movement of the weight is translated into upward movement of the control rod. The preferred control rod drive further includes an electric motor for driving the control rods under normal conditions, an electrically actuated clutch which automatically disengages the motor during a power failure and a decelerator for bringing the control rod to a controlled stop when it is inserted under emergency conditions into a reactor core.

Morphological Diversity of the Rod Spherule: A Study of Serially Reconstructed Electron Micrographs

PubMed Central

Li, Shuai; Mitchell, Joe; Briggs, Deidrie J.; Young, Jaime K.; Long, Samuel S.; Fuerst, Peter G.

2016-01-01

Purpose Rod spherules are the site of the first synaptic contact in the retina’s rod pathway, linking rods to horizontal and bipolar cells. Rod spherules have been described and characterized through electron micrograph (EM) and other studies, but their morphological diversity related to retinal circuitry and their intracellular structures have not been quantified. Most rod spherules are connected to their soma by an axon, but spherules of rods on the surface of the Mus musculus outer plexiform layer often lack an axon and have a spherule structure that is morphologically distinct from rod spherules connected to their soma by an axon. Retraction of the rod axon and spherule is often observed in disease processes and aging, and the retracted rod spherule superficially resembles rod spherules lacking an axon. We hypothesized that retracted spherules take on an axonless spherule morphology, which may be easier to maintain in a diseased state. To test our hypothesis, we quantified the spatial organization and subcellular structures of rod spherules with and without axons. We then compared them to the retracted spherules in a disease model, mice that overexpress Dscam (Down syndrome cell adhesion molecule), to gain a better understanding of the rod synapse in health and disease. Methods We reconstructed serial EM images of wild type and DscamGoF (gain of function) rod spherules at a resolution of 7 nm in the X-Y axis and 60 nm in the Z axis. Rod spherules with and without axons, and retracted spherules in the DscamGoF retina, were reconstructed. The rod spherule intracellular organelles, the invaginating dendrites of rod bipolar cells and horizontal cell axon tips were also reconstructed for statistical analysis. Results Stereotypical rod (R1) spherules occupy the outer two-thirds of the outer plexiform layer (OPL), where they present as spherical terminals with large mitochondria. This spherule group is highly uniform and composed more than 90% of the rod spherule population. Rod spherules lacking an axon (R2) were also described and characterized. This rod spherule group consists of a specific spatial organization that is strictly located at the apical OPL-facing layer of the Outer Nuclear Layer (ONL). The R2 spherule displays a large bowl-shaped synaptic terminal that hugs the rod soma. Retracted spherules in the DscamGoF retina were also reconstructed to test if they are structurally similar to R2 spherules. The misplaced rod spherules in DscamGoF have a gross morphology that is similar to R2 spherules but have significant disruption in internal synapse organization. Conclusion We described a morphological diversity within Mus musculus rod spherules. This diversity is correlated with rod location in the ONL and contributes to the intracellular differences within spherules. Analysis of the DscamGoF retina indicated that their R2 spherules are not significantly different than wild type R2 spherules, but that their retracted rod spherules have abnormal synaptic organization. PMID:26930660

Morphological Diversity of the Rod Spherule: A Study of Serially Reconstructed Electron Micrographs.

PubMed

Li, Shuai; Mitchell, Joe; Briggs, Deidrie J; Young, Jaime K; Long, Samuel S; Fuerst, Peter G

2016-01-01

Rod spherules are the site of the first synaptic contact in the retina's rod pathway, linking rods to horizontal and bipolar cells. Rod spherules have been described and characterized through electron micrograph (EM) and other studies, but their morphological diversity related to retinal circuitry and their intracellular structures have not been quantified. Most rod spherules are connected to their soma by an axon, but spherules of rods on the surface of the Mus musculus outer plexiform layer often lack an axon and have a spherule structure that is morphologically distinct from rod spherules connected to their soma by an axon. Retraction of the rod axon and spherule is often observed in disease processes and aging, and the retracted rod spherule superficially resembles rod spherules lacking an axon. We hypothesized that retracted spherules take on an axonless spherule morphology, which may be easier to maintain in a diseased state. To test our hypothesis, we quantified the spatial organization and subcellular structures of rod spherules with and without axons. We then compared them to the retracted spherules in a disease model, mice that overexpress Dscam (Down syndrome cell adhesion molecule), to gain a better understanding of the rod synapse in health and disease. We reconstructed serial EM images of wild type and DscamGoF (gain of function) rod spherules at a resolution of 7 nm in the X-Y axis and 60 nm in the Z axis. Rod spherules with and without axons, and retracted spherules in the DscamGoF retina, were reconstructed. The rod spherule intracellular organelles, the invaginating dendrites of rod bipolar cells and horizontal cell axon tips were also reconstructed for statistical analysis. Stereotypical rod (R1) spherules occupy the outer two-thirds of the outer plexiform layer (OPL), where they present as spherical terminals with large mitochondria. This spherule group is highly uniform and composed more than 90% of the rod spherule population. Rod spherules lacking an axon (R2) were also described and characterized. This rod spherule group consists of a specific spatial organization that is strictly located at the apical OPL-facing layer of the Outer Nuclear Layer (ONL). The R2 spherule displays a large bowl-shaped synaptic terminal that hugs the rod soma. Retracted spherules in the DscamGoF retina were also reconstructed to test if they are structurally similar to R2 spherules. The misplaced rod spherules in DscamGoF have a gross morphology that is similar to R2 spherules but have significant disruption in internal synapse organization. We described a morphological diversity within Mus musculus rod spherules. This diversity is correlated with rod location in the ONL and contributes to the intracellular differences within spherules. Analysis of the DscamGoF retina indicated that their R2 spherules are not significantly different than wild type R2 spherules, but that their retracted rod spherules have abnormal synaptic organization.

Parametric optimization and design validation based on finite element analysis of hybrid socket adapter for transfemoral prosthetic knee.

PubMed

Kumar, Neelesh

2014-10-01

Finite element analysis has been universally employed for the stress and strain analysis in lower extremity prosthetics. The socket adapter was the principal subject of interest due to its importance in deciding the knee motion range. This article focused on the static and dynamic stress analysis of the designed hybrid adapter developed by the authors. A standard mechanical design validation approach using von Mises was followed. Four materials were considered for the analysis, namely, carbon fiber, oil-filled nylon, Al-6061, and mild steel. The paper analyses the static and dynamic stress on designed hybrid adapter which incorporates features of conventional male and female socket adapters. The finite element analysis was carried out for possible different angles of knee flexion simulating static and dynamic gait situation. Research was carried out on available design of socket adapter. Mechanical design of hybrid adapter was conceptualized and a CAD model was generated using Inventor modelling software. Static and dynamic stress analysis was carried out on different materials for optimization. The finite element analysis was carried out on the software Autodesk Inventor Professional Ver. 2011. The peak value of von Mises stress occurred in the neck region of the adapter and in the lower face region at rod eye-adapter junction in static and dynamic analyses, respectively. Oil-filled nylon was found to be the best material among the four with respect to strength, weight, and cost. Research investigations on newer materials for development of improved prosthesis will immensely benefit the amputees. The study analyze the static and dynamic stress on the knee joint adapter to provide better material used for hybrid design of adapter. © The International Society for Prosthetics and Orthotics 2013.

Dark adaptation-induced changes in rod, cone and intrinsically photosensitive retinal ganglion cell (ipRGC) sensitivity differentially affect the pupil light response (PLR).

PubMed

Wang, Bin; Shen, Chao; Zhang, Lei; Qi, Linsong; Yao, Lu; Chen, Jianzhang; Yang, Guoqing; Chen, Tao; Zhang, Zuoming

2015-11-01

Our purpose was to explore pupil light response (PLR) with respect to the change in sensitivity of photoreceptors during various dark adaptation phases and to determine the optimal duration of dark adaptation time before the PLR. The PLR was recorded in 15 healthy subjects and three patients with neural or retinal vision loss after 1-sec blue and red light stimuli of 1, 10, and 100 cd/m(2). The PLR was repeated nine times at different checkpoints during the 40-minute dark adaptation. The transient contraction amplitude, sustained contraction amplitude, and relative sustained contraction ratio of the PLR were analyzed. The increase in the transient contraction amplitude during the entire dark adaptation process was significant (changing up to 45.1 %) in the initial phase of dark adaptation under different stimulus conditions. The changes in the sustained contraction amplitude and the relative sustained contraction ratio were substantial (changing up to 71.0 % and 37.2 % from 1 to 20 minutes of dark adaptation, respectively) under high-intensity blue illumination. The inflection point of the contraction curves in the dark adaptation was 15 or 20 minutes. The patients' PLR results changed in a similar manner. The changes in the sensitivity of different photoreceptors occurred at different rates, and the contraction amplitude of the PLR was significantly affected by the dark adaptation duration. So 20 minutes of dark adaptation before PLR testing was suggested to achieve a consistent and stable pupil response. The dark adaptation effect should be put into consideration when comparing the results from different phases of the PLR test.

78 FR 76815 - Steel Threaded Rod From India: Preliminary Affirmative Countervailing Duty Determination and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-19

... DEPARTMENT OF COMMERCE International Trade Administration [C-533-856] Steel Threaded Rod From... exporters of steel threaded rod from India. The period of investigation (``POI'') is January 1, 2012... this investigation is steel threaded rod. Steel threaded rod is certain threaded rod, bar, or studs, of...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamburello, David A.; McWilliams, Anthony J.; Hardy, Bruce J.

Vessel assemblies, heat transfer units for prefabricated vessels, and methods for heat transfer prefabricated vessel are provided. A heat transfer unit includes a central rod, and a plurality of peripheral rods surrounding the central rod and connected to the central rod. The plurality of peripheral rods are movable between a first collapsed position and a second bowed position, wherein in the second bowed position a midpoint of each of the plurality of peripheral rods is spaced from the central rod relative to in the first position. The heat transfer unit further includes a heat transfer element connected to one ofmore » the plurality of peripheral rods.« less

Intraoperative implant rod three-dimensional geometry measured by dual camera system during scoliosis surgery.

PubMed

Salmingo, Remel Alingalan; Tadano, Shigeru; Abe, Yuichiro; Ito, Manabu

2016-05-12

Treatment for severe scoliosis is usually attained when the scoliotic spine is deformed and fixed by implant rods. Investigation of the intraoperative changes of implant rod shape in three-dimensions is necessary to understand the biomechanics of scoliosis correction, establish consensus of the treatment, and achieve the optimal outcome. The objective of this study was to measure the intraoperative three-dimensional geometry and deformation of implant rod during scoliosis corrective surgery.A pair of images was obtained intraoperatively by the dual camera system before rotation and after rotation of rods during scoliosis surgery. The three-dimensional implant rod geometry before implantation was measured directly by the surgeon and after surgery using a CT scanner. The images of rods were reconstructed in three-dimensions using quintic polynomial functions. The implant rod deformation was evaluated using the angle between the two three-dimensional tangent vectors measured at the ends of the implant rod.The implant rods at the concave side were significantly deformed during surgery. The highest rod deformation was found after the rotation of rods. The implant curvature regained after the surgical treatment.Careful intraoperative rod maneuver is important to achieve a safe clinical outcome because the intraoperative forces could be higher than the postoperative forces. Continuous scoliosis correction was observed as indicated by the regain of the implant rod curvature after surgery.

Sport prostheses and prosthetic adaptations for the upper and lower limb amputees: an overview of peer reviewed literature.

PubMed

Bragaru, Mihai; Dekker, Rienk; Geertzen, Jan H B

2012-09-01

Sport prostheses are used by both upper- and lower-limb amputees while participating in sports and other physical activities. Although the number of these devices has increased over the past decade, no overview of the peer reviewed literature describing them has been published previously. Such an overview will allow specialists to choose appropriate prostheses based on available scientific evidence rather than on personal experience or preference. To provide an overview of the sport prostheses as they are described by the papers published in peer reviewed literature. Literature review. Four electronic databases were searched using free text and Medical Subject Headings (MESH) terms. Papers were included if they concerned a prosthesis or a prosthetic adaptation used in sports. Papers were excluded if they did not originate from peer reviewed sources, if they concerned prostheses for body parts other than the upper or lower limbs, if they concerned amputations distal to the wrist or ankle, or if they were written in a language other than English. Twenty-four papers were included in this study. The vast majority contained descriptive data and consisted of expert opinions and technical notes. Data concerning the energy efficiency, technical characteristics and special mechanical properties of prostheses or prosthetic adaptations for sports, other than running, are scarce.

76 FR 78882 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Affirmative Preliminary Determination of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-20

... Steel Wire Rod From Mexico: Affirmative Preliminary Determination of Circumvention of the Antidumping.... SUMMARY: We preliminarily determine that carbon and certain alloy steel wire rod (wire rod) with an actual.... de C.V. (Deacero) is circumventing the antidumping duty order on wire rod from Mexico (Wire Rod Order...

Biomechanical advantages of supplemental accessory and satellite rods with and without interbody cages implantation for the stabilization of pedicle subtraction osteotomy.

PubMed

La Barbera, Luigi; Brayda-Bruno, Marco; Liebsch, Christian; Villa, Tomaso; Luca, Andrea; Galbusera, Fabio; Wilke, Hans-Joachim

2018-05-08

To investigate the effect of anterior interbody cages, accessory and satellite rods usage on primary stability and rod strains for PSO stabilization. Seven human cadaveric spine segments (T12-S1) underwent PSO at L4 with posterior fixation from L2 to S1. In vitro flexibility tests were performed under pure moments in flexion/extension (FE), lateral bending (LB) and axial rotation (AR) to determine the range of motion, while measuring the strains on the primary rods with strain gauge rosettes. Six constructs with 2, 3 and 4 rods, with and without interbody cages implantation adjacent to the PSO site, were compared. All constructs had comparable effects in reducing spine kinematics compared to the intact condition (- 94% in FE and LB; - 80% in AR). Supplementation of 2 rods with lateral accessory rods (4 rods) was the most effective strategy in minimizing primary rod strains, particularly when coupled to cages (p ≤ 0.005; - 50% in FE, - 42% in AR and - 11% in LB); even without cages, the strains were significantly reduced (p ≤ 0.009; - 26%, - 37%, - 9%). The addition of a central satellite rod with laminar hooks (3 rods) effectively reduced rod strains in FE (p ≤ 0.005; - 30%) only in combination with cages. The study supports the current clinical practice providing a strong biomechanical rationale to recommend 4-rod constructs based on accessory rods combined with cages adjacent to PSO site. Although weaker, the usage of accessory rods without cages and of a central satellite rod with hooks in combination with interbody spacers may also be justified. These slides can be retrieved under Electronic Supplementary Material.

Conidial Hydrophobins of Aspergillus fumigatus

PubMed Central

Paris, Sophie; Debeaupuis, Jean-Paul; Crameri, Reto; Carey, Marilyn; Charlès, Franck; Prévost, Marie Christine; Schmitt, Christine; Philippe, Bruno; Latgé, Jean Paul

2003-01-01

The surface of Aspergillus fumigatus conidia, the first structure recognized by the host immune system, is covered by rodlets. We report that this outer cell wall layer contains two hydrophobins, RodAp and RodBp, which are found as highly insoluble complexes. The RODA gene was previously characterized, and ΔrodA conidia do not display a rodlet layer (N. Thau, M. Monod, B. Crestani, C. Rolland, G. Tronchin, J. P. Latgé, and S. Paris, Infect. Immun. 62:4380-4388, 1994). The RODB gene was cloned and disrupted. RodBp was highly homologous to RodAp and different from DewAp of A. nidulans. ΔrodB conidia had a rodlet layer similar to that of the wild-type conidia. Therefore, unlike RodAp, RodBp is not required for rodlet formation. The surface of ΔrodA conidia is granular; in contrast, an amorphous layer is present at the surface of the conidia of the ΔrodA ΔrodB double mutant. These data show that RodBp plays a role in the structure of the conidial cell wall. Moreover, rodletless mutants are more sensitive to killing by alveolar macrophages, suggesting that RodAp or the rodlet structure is involved in the resistance to host cells. PMID:12620846

Surface properties of sprayed and electrodeposited ZnO rod layers

NASA Astrophysics Data System (ADS)

Gromyko, I.; Krunks, M.; Dedova, T.; Katerski, A.; Klauson, D.; Oja Acik, I.

2017-05-01

Herein we present a comparative study on as-deposited, two-month-stored, and heat-treated ZnO rods obtained by spray pyrolysis (SP) at 550 °C, and electrodeposition (ED) at 80 °C. The aim of the study is to establish the reason for different behaviour of wettability and photocatalytic activity (PA) of SP and ED rods. Samples were studied using XPS, SEM, XRD, Raman, contact angle (CA) measurements and photocatalytic oxidation of doxycycline. Wettability and PA are mainly controlled by surface composition rather than by morphology. The relative amount of hydroxyl groups on the surface of as-deposited ED rods is four times higher compared to as-deposited SP rods. Opposite to SP rods, ED rods contain oxygen vacancy defects (Vo). Therefore, as-deposited ED rods are superhydrophilic (CA ∼ 3°) and show highest PA among studied samples, being three times higher compared to SP rods (removing of 75% of doxycycline after 30 min). It was revealed that as-deposited ED rods are inclined to faster contamination. The amount of Cdbnd C groups on the surface of aged ED rods is six times higher compared to aged SP rods. Stored ED samples become hydrophobic (CA ∼ 120°) and PA decreases sharply while SP rods remain hydrophilic (CA ∼ 50°), being more resistive to the contamination.

A Comparison of Motor Adaptations to Robotically Facilitated Upper Extremity Task Practice Demonstrated by Children with Cerebral Palsy and Adults with Stroke

PubMed Central

Qiu, Qinyin; Adamovich, Sergei; Saleh, Soha; Lafond, Ian; Merians, Alma S.; Fluet, Gerard G.

2015-01-01

Nine children with cerebral palsy and nine adults with stroke were trained using 5 different upper extremity simulations using the NJIT-RAVR system for approximately nine to twelve hours over a three week period. Both groups made improvements in clinical measurements of upper extremity function and reaching kinematics. Patterns and magnitudes of improvement differ between the two groups. Responses to training required adjustment of the robotic system to accommodate the rehabilitation needs of children with cerebral palsy. PMID:22275632

Direct simulation Monte Carlo prediction of on-orbit contaminant deposit levels for HALOE

NASA Technical Reports Server (NTRS)

Woronowicz, Michael S.; Rault, Didier F. G.

1994-01-01

A three-dimensional version of the direct simulation Monte Carlo method is adapted to assess the contamination environment surrounding a highly detailed model of the Upper Atmosphere Research Satellite. Emphasis is placed on simulating a realistic, worst-case set of flow field and surface conditions and geometric orientations for the satellite in order to estimate an upper limit for the cumulative level of volatile organic molecular deposits at the aperture of the Halogen Occultation Experiment. A detailed description of the adaptation of this solution method to the study of the satellite's environment is also presented. Results pertaining to the satellite's environment are presented regarding contaminant cloud structure, cloud composition, and statistics of simulated molecules impinging on the target surface, along with data related to code performance. Using procedures developed in standard contamination analyses, along with many worst-case assumptions, the cumulative upper-limit level of volatile organic deposits on HALOE's aperture over the instrument's 35-month nominal data collection period is estimated at about 13,350 A.

FUEL ROD ASSEMBLY

DOEpatents

Hutter, E.

1959-09-01

A cluster of nuclear fuel rods aod a tubular casing through which a coolant flows in heat-change contact with the ruel rods are described. The casting is of trefoil section and carries the fuel rods, each of which has two fin engaging the serrated fins of the other two fuel rods, whereby the fuel rods are held in the casing and are interlocked against relative longitudinal movement.

Heat transfer unit and method for prefabricated vessel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamburello, David A.; Kesterson, Matthew R; Hardy, Bruce J.

Vessel assemblies, heat transfer units for prefabricated vessels, and methods for heat transfer prefabricated vessel are provided. A heat transfer unit includes a central rod, and a plurality of peripheral rods surrounding the central rod and connected to the central rod. The plurality of peripheral rods are movable between a first collapsed position and a second bowed position, wherein in the second bowed position a midpoint of each of the plurality of peripheral rods is spaced from the central rod relative to in the first position. The heat transfer unit further includes a heat transfer element connected to one ofmore » the plurality of peripheral rods.« less

Results of a Neutronic Simulation of HTR-Proteus Core 4.2 using PEBBED and other INL Reactor Physics Tools: FY-09 Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hans D. Gougar

The Idaho National Laboratory’s deterministic neutronics analysis codes and methods were applied to the computation of the core multiplication factor of the HTR-Proteus pebble bed reactor critical facility. A combination of unit cell calculations (COMBINE-PEBDAN), 1-D discrete ordinates transport (SCAMP), and nodal diffusion calculations (PEBBED) were employed to yield keff and flux profiles. Preliminary results indicate that these tools, as currently configured and used, do not yield satisfactory estimates of keff. If control rods are not modeled, these methods can deliver much better agreement with experimental core eigenvalues which suggests that development efforts should focus on modeling control rod andmore » other absorber regions. Under some assumptions and in 1D subcore analyses, diffusion theory agrees well with transport. This suggests that developments in specific areas can produce a viable core simulation approach. Some corrections have been identified and can be further developed, specifically: treatment of the upper void region, treatment of inter-pebble streaming, and explicit (multiscale) transport modeling of TRISO fuel particles as a first step in cross section generation. Until corrections are made that yield better agreement with experiment, conclusions from core design and burnup analyses should be regarded as qualitative and not benchmark quality.« less

Traumatic Posterior Atlantoaxial Dislocation Without Associated Fracture but With Neurological Deficit

PubMed Central

Xu, Yong; Li, Feng; Guan, Hanfeng; Xiong, Wei

2015-01-01

Abstract Posterior atlantoaxial dislocation without odontoid fracture is extremely rare and often results in fatal spinal cord injury. According to the reported literature, all cases presented mild or no neurologic deficit, with no definite relation to upper spinal cord injury. Little is reported about traumatic posterior atlantoaxial dislocation, with incomplete quadriplegia associated with a spinal cord injury. We present a case of posterior atlantoaxial dislocation without associated fracture, but with quadriplegia, and accompanying epidural hematoma and subarachnoid hemorrhage. The patient underwent gentle traction in the neutral position until repeated cranial computed tomography revealed no progression of the epidural hematoma. Thereafter, the atlantoaxial dislocation was reduced by using partial odontoidectomy via a video-assisted transcervical approach and maintained with posterior polyaxial screw-rod constructs and an autograft. Neurological status improved immediately after surgery, and the patient recovered completely after 1 year. Posterior fusion followed by closed reduction is the superior strategy for posterior atlantoaxial dislocation without odontoid fracture, according to literature. But for cases with severe neurological deficit, open reduction may be the safest choice to avoid the lethal complication of overdistraction of the spinal cord. Also, open reduction and posterior srew-rod fixation are safe and convenient strategies in dealing with traumatic posterior atlantoaxial dislocation patients with neurological deficit. PMID:26512572

Contactless heater floating zone refining and crystal growth

NASA Technical Reports Server (NTRS)

Lan, Chung-Wen (Inventor); Kou, Sindo (Inventor)

1993-01-01

Floating zone refining or crystal growth is carried out by providing rapid relative rotation of a feed rod and finish rod while providing heat to the junction between the two rods so that significant forced convection occurs in the melt zone between the two rods. The forced convection distributes heat in the melt zone to allow the rods to be melted through with a much shorter melt zone length than possible utilizing conventional floating zone processes. One of the rods can be rotated with respect to the other, or both rods can be counter-rotated, with typical relative rotational speeds of the rods ranging from 200 revolutions per minute (RPM) to 400 RPM or greater. Zone refining or crystal growth is carried out by traversing the melt zone through the feed rod.

Preclinical evaluation of posterior spine stabilization devices: can the current standards represent basic everyday life activities?

PubMed

La Barbera, Luigi; Galbusera, Fabio; Wilke, Hans-Joachim; Villa, Tomaso

2016-09-01

To discuss whether the available standard methods for preclinical evaluation of posterior spine stabilization devices can represent basic everyday life activities and how to compare the results obtained with different procedures. A comparative finite element study compared ASTM F1717 and ISO 12189 standards to validated instrumented L2-L4 segments undergoing standing, upper body flexion and extension. The internal loads on the spinal rod and the maximum stress on the implant are analysed. ISO recommended anterior support stiffness and force allow for reproducing bending moments measured in vivo on an instrumented physiological segment during upper body flexion. Despite the significance of ASTM model from an engineering point of view, the overly conservative vertebrectomy model represents an unrealistic worst case scenario. A method is proposed to determine the load to apply on assemblies with different anterior support stiffnesses to guarantee a comparable bending moment and reproduce specific everyday life activities. The study increases our awareness on the use of the current standards to achieve meaningful results easy to compare and interpret.

Graphite/epoxy composite adapters for the Space Shuttle/Centaur vehicle

NASA Technical Reports Server (NTRS)

Kasper, Harold J.; Ring, Darryl S.

1990-01-01

The decision to launch various NASA satellite and Air Force spacecraft from the Space Shuttle created the need for a high-energy upper stage capable of being deployed from the cargo bay. Two redesigned versions of the Centaur vehicle which employed a graphite/epoxy composite material for the forward and aft adapters were selected. Since this was the first time a graphite/epoxy material was used for Centaur major structural components, the development of the adapters was a major effort. An overview of the composite adapter designs, subcomponent design evaluation test results, and composite adapter test results from a full-scale vehicle structural test is presented.

Getting It Out, Getting It Down: Adapting Zoellner's Talk-Write.

ERIC Educational Resources Information Center

Wixon, Vincent; Stone, Patty

The Talk-Write method of teaching college composition, developed by Robert Zoellner, can be adapted for use in secondary and upper elementary classrooms. The method, which focuses on the process of writing, involves teaming students in pairs. One student then talks out a composition, sentence by sentence, while the partner asks questions to draw…

CRUCIFORM CONTROL ROD JOINT

DOEpatents

Thorp, A.G. II

1962-08-01

An invention is described which relates to nuclear reactor control rod components and more particularly to a joint between cruciform control rod members and cruciform control rod follower members. In one embodiment this invention provides interfitting crossed arms at adjacent ends of a control rod and its follower in abutting relation. This holds the members against relative opposite longitudinal movement while a compression member keys the arms against relative opposite rotation around a common axis. Means are also provided for centering the control rod and its follower on a common axis and for selectively releasing the control rod from its follower for the insertion of a replacement of the control rod and reuse of the follower. (AEC)

Stimulus-evoked outer segment changes in rod photoreceptors

NASA Astrophysics Data System (ADS)

Zhao, Xiaohui; Thapa, Damber; Wang, Benquan; Lu, Yiming; Gai, Shaoyan; Yao, Xincheng

2016-06-01

Rod-dominated transient retinal phototropism (TRP) has been recently observed in freshly isolated mouse and frog retinas. Comparative confocal microscopy and optical coherence tomography revealed that the TRP was predominantly elicited from the rod outer segment (OS). However, the biophysical mechanism of rod OS dynamics is still unknown. Mouse and frog retinal slices, which displayed a cross-section of retinal photoreceptors and other functional layers, were used to test the effect of light stimulation on rod OSs. Time-lapse microscopy revealed stimulus-evoked conformational changes of rod OSs. In the center of the stimulated region, the length of the rod OS shrunk, while in the peripheral region, the rod OS swung toward the center region. Our experimental observation and theoretical analysis suggest that the TRP may reflect unbalanced rod disc-shape changes due to localized visible light stimulation.

Stimulus-evoked outer segment changes in rod photoreceptors

PubMed Central

Zhao, Xiaohui; Thapa, Damber; Wang, Benquan; Lu, Yiming; Gai, Shaoyan; Yao, Xincheng

2016-01-01

Abstract. Rod-dominated transient retinal phototropism (TRP) has been recently observed in freshly isolated mouse and frog retinas. Comparative confocal microscopy and optical coherence tomography revealed that the TRP was predominantly elicited from the rod outer segment (OS). However, the biophysical mechanism of rod OS dynamics is still unknown. Mouse and frog retinal slices, which displayed a cross-section of retinal photoreceptors and other functional layers, were used to test the effect of light stimulation on rod OSs. Time-lapse microscopy revealed stimulus-evoked conformational changes of rod OSs. In the center of the stimulated region, the length of the rod OS shrunk, while in the peripheral region, the rod OS swung toward the center region. Our experimental observation and theoretical analysis suggest that the TRP may reflect unbalanced rod disc-shape changes due to localized visible light stimulation. PMID:27334933

An Adaptive Security Construct: Insurgency in Sudan

DTIC Science & Technology

2007-12-01

and “External Actors” existing as both foundational and supporting relatives. The “ Legs ” between cornerpoints, in addition to defining the tactical...directly. In a simplified mirror-image, the same progression of legs underlies each side’s connection with international or non-governmental external...Technologies ( DTI ), March 21, 2007). 45 Ghazal, Lakes, and Warab), and Upper Nile (Junqali, Wahdah, and Upper Nile).94 Allegations of corruption persist

Tapered laser rods as a means of minimizing the path length of trapped barrel mode rays

DOEpatents

Beach, Raymond J.; Honea, Eric C.; Payne, Stephen A.; Mercer, Ian; Perry, Michael D.

2005-08-30

By tapering the diameter of a flanged barrel laser rod over its length, the maximum trapped path length of a barrel mode can be dramatically reduced, thereby reducing the ability of the trapped spontaneous emission to negatively impact laser performance through amplified spontaneous emission (ASE). Laser rods with polished barrels and flanged end caps have found increasing application in diode array end-pumped laser systems. The polished barrel of the rod serves to confine diode array pump light within the rod. In systems utilizing an end-pumping geometry and such polished barrel laser rods, the pump light that is introduced into one or both ends of the laser rod, is ducted down the length of the rod via the total internal reflections (TIRs) that occur when the light strikes the rod's barrel. A disadvantage of using polished barrel laser rods is that such rods are very susceptible to barrel mode paths that can trap spontaneous emission over long path lengths. This trapped spontaneous emission can then be amplified through stimulated emission resulting in a situation where the stored energy available to the desired lasing mode is effectively depleted, which then negatively impacts the laser's performance, a result that is effectively reduced by introducing a taper onto the laser rod.

Predator protection versus rapid growth in a montane leaf beetle.

PubMed

Smiley, John T; Rank, Nathan E

1986-08-01

Adults and larvae of Chrysomela aenicollis (Coleoptera: Chrysomelidae) feed on foliage of Salix species (Salicaceae) between 2,400-3,400 m above sea level in the eastcentral Sierra Nevada mountains of California. We predicted that (1) cold climatic conditions would be a more frequent source of mortality at higher elevations, (2) mildweather agents of mortality such as predation should be more severe at lower elevations, and (3) populations of C. aenicollis would be adapted to the local selective regime at each elevation. We tested these predictions in 1984 and 1985 by transferring over 6,000 eggs and larvae within and between two sites at 2,810 and 3,240 m elevation above sea level. During mild summer weather at both sites, survivorship on Salix branches isolated by a barrier of sticky resin was similar to that on control branches, and we concluded that aerial predators were the primary cause of mortality. At least one major predator, a solitary wasp (Symmorphus sp., Hymenoptera: Eumenidae), was specifically associated with C. aenicollis at the lower site, where beetle mortality was highest. At both sites in 1984 and 1985, larvae originating from the lower site remained in aggregations and survived more frequently than larvae from the upper site, suggesting that they are better defended against predators. During a storm with cold weather late in the 1984 season, larvae and pupae died more frequently at the upper site, and there was a marginally significant trend (P<0.1) for the lower site individuals to die more frequently than upper site larvae during the cold storm. Upper site larvae grew approximately 10% faster than lower site larvae at the lower site and under controlled conditions in the laboratory. These findings indicate that upper and lower site populations were adapted to the local selective regime, which suggest how populations of montane phytopagous insects may adapt to changing elevations.

Investigation of multi-stage cold forward extrusion process using coupled thermo-mechanical finite element analysis

NASA Astrophysics Data System (ADS)

Görtan, Mehmet Okan

2018-05-01

Cold extrusion processes are distinguished by their low material usage as well as great efficiency in the production of mid-range and large component series. Although majority of the cold extruded parts are produced using die systems containing multiple forming stages, this subject has rarely been investigated so far. Therefore, the characteristics of multi-stage cold forward rod extrusion is studied in the current work using thermo-mechanically coupled finite element (FE) analysis. A case hardening steel, 16MnCr5 (1.7131) was used as experimental material. Its strain, strain rate and temperature dependent mechanical characteristics were determined using compression testing and modeled in FE simulations via a Johnson-Cook material model. Friction coefficients for the same material while in contact with a tool steel (1.2379) were determined dependent on temperature and contact pressure using sliding compression test (SCT) and modeled by an adaptive friction model developed by the author. In the first set of simulations, rod material with a diameter of 14.9 mm was extruded down to a diameter of 9.6 mm in a single step using three different die opening angles (2α); 20°, 40° and 60°. In the second set of investigations, the same rod was reduced first to 12 mm and then to 9.6 mm in two steps within the same forming die. Press forces, contact normal stresses between extruded material and forming die, material temperature and axial stresses are compared in these two set of simulations and the differences are discussed.

Simultaneous enhancement of phenolic compound degradations by Acinetobacter strain V2 via a step-wise continuous acclimation process.

PubMed

Lin, Johnson; Sharma, Vikas; Milase, Ridwaan; Mbhense, Ntuthuko

2016-06-01

Phenol degradation enhancement of Acinetobacter strain V2 by a step-wise continuous acclimation process was investigated. At the end of 8 months, three stable adapted strains, designated as R, G, and Y, were developed with the sub-lethal concentration of phenol at 800, 1100, and 1400 mg/L, respectively, from 400 mg/L of V2 parent strain. All strains degraded phenol at their sub-lethal level within 24 h, their growth rate increased as the acclimation process continued and retained their degradation properties even after storing at -80 °C for more than 3 years. All adapted strains appeared coccoid with an ungranulated surface under electron microscope compared to typical rod-shaped parental strain V2 . The adapted Y strain also possessed superior degradation ability against aniline, benzoate, and toluene. This study demonstrated the use of long term acclimation process to develop efficient and better pollutant degrading bacterial strains with potentials in industrial and environmental bioremediation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced butyric acid tolerance and bioproduction by Clostridium tyrobutyricum immobilized in a fibrous bed bioreactor.

PubMed

Jiang, Ling; Wang, Jufang; Liang, Shizhong; Cai, Jin; Xu, Zhinan; Cen, Peilin; Yang, Shangtian; Li, Shuang

2011-01-01

Repeated fed-batch fermentation of glucose by Clostridium tyrobutyricum immobilized in a fibrous bed bioreactor (FBB) was successfully employed to produce butyric acid at a high final concentration as well as to adapt a butyric-acid-tolerant strain. At the end of the eighth fed-batch fermentation, the butyric acid concentration reached 86.9 ± 2.17 g/L, which to our knowledge is the highest butyric acid concentration ever produced in the traditional fermentation process. To understand the mechanism and factors contributing to the improved butyric acid production and enhanced acid tolerance, adapted strains were harvested from the FBB and characterized for their physiological properties, including specific growth rate, acid-forming enzymes, intracellular pH, membrane-bound ATPase and cell morphology. Compared with the original culture used to seed the bioreactor, the adapted culture showed significantly reduced inhibition effects of butyric acid on specific growth rate, cellular activities of butyric-acid-forming enzyme phosphotransbutyrylase (PTB) and ATPase, together with elevated intracellular pH, and elongated rod morphology. © 2010 Wiley Periodicals, Inc.

The Moment of Inertia of a Rectangular Rod

NASA Astrophysics Data System (ADS)

Takeuchi, Takao

2007-11-01

Recently an inexpensive setup to obtain the moment of inertia of a rotating system was proposed by Peter E. Banks. An equally simple and inexpensive experiment to obtain the moment of inertia of a uniform rod is proposed in this paper. A rectangular rod with a hole somewhere in the rod was used for this purpose. The moment of inertia of a rectangular rod around the hole location was attempted. The experimental setup is shown in Fig. 1. Various supporting rods, clamps, and rubber stoppers to hold the rectangular rod in place at point p are not shown.

Nuclear thermionic converter. [tungsten-thorium oxide rods

NASA Technical Reports Server (NTRS)

Phillips, W. M.; Mondt, J. F. (Inventor)

1977-01-01

Efficient nuclear reactor thermionic converter units are described which can be constructed at low cost and assembled in a reactor which requires a minimum of fuel. Each converter unit utilizes an emitter rod with a fluted exterior, several fuel passages located in the bulges that are formed in the rod between the flutes, and a collector receiving passage formed through the center of the rod. An array of rods is closely packed in an interfitting arrangement, with the bulges of the rods received in the recesses formed between the bulges of other rods, thereby closely packing the nuclear fuel. The rods are constructed of a mixture of tungsten and thorium oxide to provide high power output, high efficiency, high strength, and good machinability.

Lightning discharge protection rod

NASA Technical Reports Server (NTRS)

Bryan, Charles F., Jr. (Inventor)

1987-01-01

A system for protecting an in-air vehicle from damage due to a lighning strike is disclosed. It is an extremely simple device consisting of a sacrificial graphite composite rod, approximately the diameter of a pencil with a length of about five inches. The sacrificial rod is constructed with the graphite fibers running axially within the rod in a manner that best provides a path of conduction axially from the trailing edge of an aircraft to the trailing end of the rod. The sacrificial rod is inserted into an attachment hole machined into trailing edges of aircraft flight surfaces, such as a vertical fin cap and attached with adhesive in a manner not prohibiting the conduction path between the rod and the aircraft. The trailing end of the rod may be tapered for aerodynamic and esthetic requirements. This rod is sacrificial but has the capability to sustain several lightning strikes and still provide protection.

Thermomechanical effects of spine surgery rods composed of different metals and alloys.

PubMed

Noshchenko, Andriy; Patel, Vikas V; Baldini, Todd; Yun, Lu; Lindley, Emily M; Burger, Evalina L

2011-05-15

A basic science study monitoring changes in the curvature of hand contoured commercially pure titanium (CPTi), titanium-aluminum-vanadium alloy (Ti-6Al-4V), and stainless steel (SS) rods maintained at different temperature conditions. To quantify changes in rod-shape at temperatures representative of those used in clinical practice. The shape of implanted rods can be displaced due to thermo-mechanical properties of the materials. Warmer temperatures likely initiate this effect. A study of shape loss characteristics of various rod implants may help eliminate undesirable outcomes caused by shape displacement. Three different types of rods (CPTi, SS, and Ti-6Al-4V) were hand contoured and then maintained in one of following temperature conditions for 35 days: (1) room temperature (20 °C-25 °C) without autoclaving before contouring; (2) preliminary autoclaving (1, 5, 10, 20 cycles) at 135.0 °C ± 2 °C before contouring followed by body temperature (37.2 °C ± 2 °C). Each rod was 5 mm in diameter and 200 mm long. The rods were mounted over graph paper in fixed positions and photographed to measure displacement of the tip as a function of the curvature. RESULTS.: Statistically significant shape loss of the rods manufactured from all the tested materials was found. The hand contoured CPTi rods displayed considerably higher loss of curvature over time than Ti-6Al-4V and SS rods at all tested temperature conditions. Preliminary autoclaving at 135 °C before contouring tended to amplify this effect, in particular 1 cycle of autoclaving. If the number of preliminary autoclaving cycles was higher (5-10), a tendency of decrease of shape loss effect was observed in Ti-6Al-4V and CPTi rods. The shape of the hand contoured CPTi rods was the least stable of the rods across all applied temperature conditions. The SS and Ti-6Al-4V rods were more stable than CPTi rods. Autoclaving before handcontouring tended to increase rods' shape loss.

RECENT DEVELOPMENTS IN HYDROLOGIC INSTRUMENTATION.

USGS Publications Warehouse

Latkovich, Vito J.

1985-01-01

The availability of space-age materials and implementation of state-of-the-art electronics is making possible the recent developments of hydrologic instrumentation. Material developments include: Synthetic-fiber sounding and tag lines; fiberglass wading rod; polymer (plastic) sheaves, pulleys and sampler components; and polymer (plastic) bucket wheels for current meters. These materials are very cost effective and efficient. Electromechanical and electronic developments and applications include: adaptable data acquisition system; downhole sampler for hazardous substances; current-meter digitizer; hydraulic power/drive system for discharge measurements and water-quality sampling; non-contact water-level sensors; minimum data recorder; acoustic velocity meters, and automated current meter discharge-measurement system.

Use of Ultrasound to Improve the Effectiveness of a Permeable Treatment Wall

NASA Technical Reports Server (NTRS)

Quinn, Jacqueline W. (Inventor); Clausen, Christian A. (Inventor); Geiger, Cherie L. (Inventor); Reinhart, Debra R. (Inventor); Ruiz, Nancy (Inventor)

2000-01-01

A method for increasing the effectiveness of a permeable treatment wall is described. The method includes the introduction of ultrasonic radiation in or near the wall. A permeable treatment wall is also described which has an ultrasonic radiation generating transducer in or near the wall. Permeable treatment walls are described as having either a well vertically extending into the wall, or a rod vertically extending into the treatment wall. Additionally, a method for adapting a permeable treatment wall to allow for the introduction of ultrasonic radiation in or near the wall is described.

Developing rods transplanted into the degenerating retina of Crx-knockout mice exhibit neural activity similar to native photoreceptors

PubMed Central

Homma, Kohei; Okamoto, Satoshi; Mandai, Michiko; Gotoh, Norimoto; Rajasimha, Harsha K.; Chang, Yi-Sheng; Chen, Shan; Li, Wei; Cogliati, Tiziana; Swaroop, Anand; Takahashi, Masayo

2013-01-01

Replacement of dysfunctional or dying photoreceptors offers a promising approach for retinal neurodegenerative diseases, including age-related macular degeneration and retinitis pigmentosa. Several studies have demonstrated the integration and differentiation of developing rod photoreceptors when transplanted in wild type or degenerating retina; however, the physiology and function of the donor cells are not adequately defined. Here, we describe the physiological properties of developing rod photoreceptors that are tagged with GFP driven by the promoter of rod differentiation factor, Nrl. GFP-tagged developing rods show Ca2+ responses and rectifier outward currents that are smaller than those observed in fully developed photoreceptors, suggesting their immature developmental state. These immature rods also exhibit hyperpolarization-activated current (Ih) induced by the activation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. When transplanted into the subretinal space of wild type or retinal degeneration mice, GFP-tagged developing rods can integrate into the photoreceptor outer nuclear layer in wild-type mouse retina, and exhibit Ca2+ responses and membrane current comparable to native rod photoreceptors. A proportion of grafted rods develop rhodopsin-positive outer segment-like structures within two weeks after transplantation into the retina of Crx-knockout mice, and produce rectifier outward current and Ih upon membrane depolarization and hyperpolarization. GFP-positive rods derived from induced pluripotent stem (iPS) cells also display similar membrane current Ih as native developing rod photoreceptors, express rod-specific phototransduction genes, and HCN-1 channels. We conclude that Nrl-promoter driven GFP-tagged donor photoreceptors exhibit physiological characteristics of rods and that iPS cell-derived rods in vitro may provide a renewable source for cell replacement therapy. PMID:23495178

NEUTRONIC REACTOR CONTROL ROD DRIVE APPARATUS

DOEpatents

Oakes, L.C.; Walker, C.S.

1959-12-15

ABS>A suspension mechanism between a vertically movable nuclear reactor control rod and a rod extension, which also provides information for the operator or an automatic control signal, is described. A spring connects the rod extension to a drive shift. The extension of the spring indicates whether (1) the rod is at rest on the reactor, (2) the rod and extension are suspended, or (3) the extension alone is suspended, the spring controlling a 3-position electrical switch.

Analysis of the causes of recurrence after frontalis suspension using silicone rods for congenital ptosis

PubMed Central

Kim, Chang Yeom; Son, Byeong Jae; Son, Jangyup; Hong, Jongill; Lee, Sang Yeul

2017-01-01

Background Silicone rod is a commonly used synthetic suspension material in frontalis suspension surgery to correct blepharoptosis. The most challenging problem and a decisive drawback of the use of silicone rod is a considerable rate of ptosis recurrence after surgery. We examined patients with recurred ptosis and assessed the physical and micromorphological properties of implanted silicone rods to determine the causative mechanisms of recurred ptosis after frontalis suspension using silicone rod. Methods This is a prospective observational case series of 22 pediatric patients with recurred ptosis after frontalis suspension using silicone rods for congenital ptosis. Implanted silicone rods were observed and removed during the operation for correction of recurred ptosis. The removed silicone rods were physically and micromorphologically evaluated to determine the cause of recurrence. Results Pretarsal fixation positions migrated upward, whereas suprabrow fixation positions migrated downward during ptosis recurrence. The breaking strength of implanted silicone rods was reduced by approximately 50% during 3 years. Cracks, debris, and loss of homogenous structure with disintegration were observed on scanning electron micrographs of implanted silicone rods in patients with recurred ptosis. Preoperative severe degree of ptosis also contributed to recurred ptosis. Conclusions Recurrence of ptosis after frontalis suspension using silicone rod was associated with physical changes of implanted silicone rods, including positional migration, weakened tensile strength, and micromorphological changes in combination with patients’ characteristics. PMID:28207846

Mutations in cell elongation genes mreB, mrdA and mrdB suppress the shape defect of RodZ-deficient cells.

PubMed

Shiomi, Daisuke; Toyoda, Atsushi; Aizu, Tomoyuki; Ejima, Fumio; Fujiyama, Asao; Shini, Tadasu; Kohara, Yuji; Niki, Hironori

2013-03-01

RodZ interacts with MreB and both factors are required to maintain the rod shape of Escherichia coli. The assembly of MreB into filaments regulates the subcellular arrangement of a group of enzymes that synthesizes the peptidoglycan (PG) layer. However, it is still unknown how polymerization of MreB determines the rod shape of bacterial cells. Regulatory factor(s) are likely to be involved in controlling the function and dynamics of MreB. We isolated suppressor mutations to partially recover the rod shape in rodZ deletion mutants and found that some of the suppressor mutations occurred in mreB. All of the mreB mutations were in or in the vicinity of domain IA of MreB. Those mreB mutations changed the property of MreB filaments in vivo. In addition, suppressor mutations were found in the periplasmic regions in PBP2 and RodA, encoded by mrdA and mrdB genes. Similar to MreB and RodZ, PBP2 and RodA are pivotal to the cell wall elongation process. Thus, we found that mutations in domain IA of MreB and in the periplasmic domain of PBP2 and RodA can restore growth and rod shape to ΔrodZ cells, possibly by changing the requirements of MreB in the process. © 2013 Blackwell Publishing Ltd.

Mutations in cell elongation genes mreB, mrdA and mrdB suppress the shape defect of RodZ-deficient cells

PubMed Central

Shiomi, Daisuke; Toyoda, Atsushi; Aizu, Tomoyuki; Ejima, Fumio; Fujiyama, Asao; Shini, Tadasu; Kohara, Yuji; Niki, Hironori

2013-01-01

RodZ interacts with MreB and both factors are required to maintain the rod shape of Escherichia coli. The assembly of MreB into filaments regulates the subcellular arrangement of a group of enzymes that synthesizes the peptidoglycan (PG) layer. However, it is still unknown how polymerization of MreB determines the rod shape of bacterial cells. Regulatory factor(s) are likely to be involved in controlling the function and dynamics of MreB. We isolated suppressor mutations to partially recover the rod shape in rodZ deletion mutants and found that some of the suppressor mutations occurred in mreB. All of the mreB mutations were in or in the vicinity of domain IA of MreB. Those mreB mutations changed the property of MreB filaments in vivo. In addition, suppressor mutations were found in the periplasmic regions in PBP2 and RodA, encoded by mrdA and mrdB genes. Similar to MreB and RodZ, PBP2 and RodA are pivotal to the cell wall elongation process. Thus, we found that mutations in domain IA of MreB and in the periplasmic domain of PBP2 and RodA can restore growth and rod shape to ΔrodZ cells, possibly by changing the requirements of MreB in the process. PMID:23301723

78 FR 79670 - Steel Threaded Rod From Thailand: Preliminary Determination of Sales at Less Than Fair Value and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-31

... DEPARTMENT OF COMMERCE International Trade Administration [A-549-831] Steel Threaded Rod From... ``Department'') preliminarily determines that steel threaded rod from Thailand is being, or is likely to be... Investigation The merchandise covered by this investigation is steel threaded rod. Steel threaded rod is certain...

Measurement of Diffusion in Entangled Rod-Coil Triblock Copolymers

NASA Astrophysics Data System (ADS)

Olsen, B. D.; Wang, M.

2012-02-01

Although rod-coil block copolymers have attracted increasing attention for functional nanomaterials, their dynamics relevant to self-assembly and processing have not been widely investigated. Because the rod and coil blocks have different reptation behavior and persistence lengths, the mechanism by which block copolymers will diffuse is unclear. In order to understand the effect of the rigid block on reptation, tracer diffusion of a coil-rod-coil block copolymer through an entangled coil polymer matrix was experimentally measured. A monodisperse, high molecular weight coil-rod-coil triblock was synthesized using artificial protein engineering to prepare the helical rod and bioconjugaiton of poly(ethylene glycol) coils to produce the final triblock. Diffusion measurements were performed using Forced Rayleigh scattering (FRS), at varying ratios of the rod length to entanglement length, where genetic engineering is used to control the protein rod length and the polymer matrix concentration controls the entanglement length. As compared to PEO homopolymer tracers, the coil-rod-coil triblocks show markedly slower diffusion, suggesting that the mismatch between rod and coil reptation mechanisms results in hindered diffusion of these molecules in the entangled state.

Management of lower-extremity deformities in osteogenesis imperfecta with extensible intramedullary rod technique: a 20-year experience.

PubMed

Luhmann, S J; Sheridan, J J; Capelli, A M; Schoenecker, P L

1998-01-01

Twelve patients (seven boys, five girls) who had osteogenesis imperfecta were treated with an extensible-rod system in 21 femurs and 15 tibias. Indications for use of extensible rods were multiple fractures, long-bone deformity prohibiting bracing and ambulation, and significant remaining linear growth. The average patient age at the time of placement of the extensible rods was 6 + 8 years (range, 2 + 4-10 + 10). Six femurs were treated with overlapping Rush rods; Bailey-Dubow rods were used in the remaining femurs and in all tibias. The average length of follow-up was 5 + 9 years (range, 2 + 0-3 + 2). Preoperatively, four of the 12 patients had never walked; postoperatively, all were ambulators with varying levels of assistance. Fourteen complications occurred, 12 of which required operative revision of the extensible rods. The average time between primary extensible rodding and revision was 5 + 1 years. No complications have occurred to date related to the use of overlapping Rush rods. No growth disturbance resulted from the use of the extensible-rod systems.

Scientific monitoring plan in support of the selected alternative of the Glen Canyon Dam Long-Term Experimental and Management Plan

USGS Publications Warehouse

Vanderkooi, Scott P.; Kennedy, Theodore A.; Topping, David J.; Grams, Paul E.; Ward, David L.; Fairley, Helen C.; Bair, Lucas S.; Sankey, Joel B.; Yackulic, Charles B.; Schmidt, John C.

2017-01-18

IntroductionThe purpose of this document is to describe a strategy by which monitoring and research data in the natural and social sciences will be collected, analyzed, and provided to the U.S. Department of the Interior (DOI), its bureaus, and to the Glen Canyon Dam Adaptive Management Program (GCDAMP) in support of implementation of the Glen Canyon Dam Long-Term Experimental and Management Plan (LTEMP) (U.S. Department of the Interior, 2016a). The selected alternative identified in the LTEMP Record of Decision (ROD) (U.S. Department of the Interior, 2016b) describes various data collection, analysis, modeling, and interpretation efforts to be conducted by the U.S. Geological Survey’s (USGS) Grand Canyon Monitoring and Research Center (GCMRC), partner agencies, and cooperators that will inform decisions about operations of Glen Canyon Dam and management of downstream resources between 2017 and 2037, the performance period of the LTEMP. General data collection, analysis, modeling, and interpretation activities are described in this science plan, whereas specific monitoring and research activities and detailed study plans are to be described in the GCDAMP’s triennial work plans (TWPs) to be developed by the Bureau of Reclamation and GCMRC with input from partner agencies and cooperators during the LTEMP period, which are to be reviewed and recommended by the GCDAMP and approved by the Secretary of the Interior. The GCDAMP consists of several components, the primary committee being the Adaptive Management Work Group (AMWG). This Federal advisory committee is composed of 25 agencies and stakeholder groups and is chaired by the Secretary of the Interior’s designee. The AMWG makes recommendations to the Secretary of the Interior concerning operations of Glen Canyon Dam and other experimental management actions that are intended to fulfill some obligations of the Grand Canyon Protection Act of 1992. The Technical Work Group (TWG) is a subcommittee of the AMWG and provides technical advice to the AMWG. It is composed of technical and science representatives from the same agencies and stakeholder groups who serve on the AMWG. GCMRC is the primary science provider to the GCDAMP and also coordinates many aspects of the science performed by cooperators and partner agencies. The Science Advisors Program provides independent science reviews and advice at the request of the GCDAMP.The plan proposed here necessarily depends on (1) the protocol for decision-making and the requirements for scientific data reporting described in the LTEMP ROD, (2) the priorities of the GCDAMP as directed by the LTEMP ROD (see Department of the Interior, 2016b, section 6.1), (3) the priorities for monitoring and research in the conservation measures section of the Biological Opinion for the LTEMP (U.S. Department of the Interior, 2016b, LTEMP ROD attachment E), (4) the priorities for resource management and information needs established by Federal and State resource-management agencies within the GCDAMP, (5) scientific understanding about the linkage between the status of those resources and operations of Glen Canyon Dam, and (6) the need to resolve existing scientific uncertainties about the linkage between dam operations and the condition of resources. We note that resource-management prioritization is fundamentally a policy decision charged specifically to DOI for the Colorado River in Glen and Grand Canyons, as outlined most recently in the LTEMP ROD, and is not the responsibility of the GCMRC. However, it is the responsibility of the GCMRC to describe the nature of scientific understanding, the nature of scientific uncertainty, and the risk of making resourcemanagement decisions in the face of existing scientific uncertainty. The goals of science activities in the next 20 years are to inform operational decisions regarding Glen Canyon Dam operations described in the LTEMP ROD, resolve remaining scientific uncertainties, and to monitor resource trends that are affected entirely, or in part, by dam operations.

Bcl-xL-mediated remodeling of rod and cone synaptic mitochondria after postnatal lead exposure: electron microscopy, tomography and oxygen consumption.

PubMed

Perkins, Guy A; Scott, Ray; Perez, Alex; Ellisman, Mark H; Johnson, Jerry E; Fox, Donald A

2012-01-01

Postnatal lead exposure produces rod-selective and Bax-mediated apoptosis, decreased scotopic electroretinograms (ERGs), and scotopic and mesopic vision deficits in humans and/or experimental animals. Rod, but not cone, inner segment mitochondria were considered the primary site of action. However, photoreceptor synaptic mitochondria were not examined. Thus, our experiments investigated the structural and functional effects of environmentally relevant postnatal lead exposure on rod spherule and cone pedicle mitochondria and whether Bcl-xL overexpression provided neuroprotection. C57BL/6N mice pups were exposed to lead only during lactation via dams drinking water containing lead acetate. The blood [Pb] at weaning was 20.6±4.7 µg/dl, which decreased to the control value by 2 months. To assess synaptic mitochondrial structural differences and vulnerability to lead exposure, wild-type and transgenic mice overexpressing Bcl-xL in photoreceptors were used. Electron microscopy, three-dimensional electron tomography, and retinal and photoreceptor synaptic terminal oxygen consumption (QO(2)) studies were conducted in adult control, Bcl-xL, lead, and Bcl-xL/lead mice. The spherule and pedicle mitochondria in lead-treated mice were swollen, and the cristae structure was markedly changed. In the lead-treated mice, the mitochondrial cristae surface area and volume (abundance: measure correlated with ATP (ATP) synthesis) were decreased in the spherules and increased in the pedicles. Pedicles also had an increased number of crista segments per volume. In the lead-treated mice, the number of segments/crista and fraction of cristae with multiple segments (branching) similarly increased in spherule and pedicle mitochondria. Lead-induced remodeling of spherule mitochondria produced smaller cristae with more branching, whereas pedicle mitochondria had larger cristae with more branching and increased crista junction (CJ) diameter. Lead decreased dark- and light-adapted photoreceptor and dark-adapted photoreceptor synaptic terminal QO(2). Bcl-xL partially blocked many of the lead-induced alterations relative to controls. However, spherules still had partially decreased abundance, whereas pedicles still had increased branching, increased crista segments per volume, and increased crista junction diameter. Moreover, photoreceptor and synaptic QO(2) were only partially recovered. These findings reveal cellular and compartmental specific differences in the structure and vulnerability of rod and cone inner segment and synaptic mitochondria to postnatal lead exposure. Spherule and pedicle mitochondria in lead-exposed mice displayed complex and distinguishing patterns of cristae and matrix damage and remodeling consistent with studies showing that synaptic mitochondria are more sensitive to Ca(2+) overload, oxidative stress, and ATP loss than non-synaptic mitochondria. The lead-induced decreases in QO(2) likely resulted from the decreased spherule cristae abundance and smaller cristae, perhaps due to Bax-mediated effects as they occurred in apoptotic rod inner segments. The increase in pedicle cristae abundance and CJ diameter could have resulted from increased Drp1-mediated fission, as small mitochondrial fragments were observed. The mechanisms of Bcl-xL-mediated remodeling might occur via interaction with formation of CJ protein 1 (Fcj1), whereas the partial protection of synaptic QO(2) might result from the enhanced efficiency of energy metabolism via Bcl-xL's direct interaction with the F1F0 ATP synthase and/or regulation of cellular redox status. These lead-induced alterations in photoreceptor synaptic terminal mitochondria likely underlie the persistent scotopic and mesopic deficits in lead-exposed children, workers, and experimental animals. Our findings stress the clinical and scientific importance of examining synaptic dysfunction following injury or disease during development, and developing therapeutic treatments that prevent synaptic degeneration in retinal and neurodegenerative disorders even when apoptosis is blocked.

Changes in wall teichoic acid during the rod-sphere transition of Bacillus subtilis 168.

PubMed Central

Pollack, J H; Neuhaus, F C

1994-01-01

Wall teichoic acid (WTA) is essential for the growth of Bacillus subtilis 168. To clarify the function of this polymer, the WTAs of strains 168, 104 rodB1, and 113 tagF1 (rodC1) grown at 32 and 42 degrees C were characterized. At the restrictive temperature, the rodB1 and tagF1 (rodC1) mutants undergo a rod-to-sphere transition that is correlated with changes in the WTA content of the cell wall. The amount of WTA decreased 33% in strain 104 rodB1 and 84% in strain 113 tagF1 (rodC1) when they were grown at the restrictive temperature. The extent of alpha-D-glucosylation (0.84) was not affected by growth at the higher temperature in these strains. The degree of D-alanylation decreased from 0.22 to 0.10 in the rodB1 mutant but remained constant (0.12) in the tagF1 (rodC1) mutant at both temperatures. Under these conditions, the degree of D-alanylation in the parent strain decreased from 0.27 to 0.21. The chain lengths of WTA in strains 168 and 104 rodB1 grown at both temperatures were approximately 53 residues, with a range of 45 to 60. In contrast, although the chain length of WTA from the tagF1 (rodC1) mutant at 32 degrees C was similar to that of strains 168 and 104 rodB1, it was approximately eight residues at the restrictive temperature. The results suggested that the rodB1 mutant is partially deficient in completed poly(glycerophosphate) chains. The precise biochemical defect in this mutant remains to be determined. The results for strain 113 tagF1(rodC1) are consistent with the temperature-sensitive defect in the CDP-glycerol:poly(glycerophosphate) glycerophosphotransferase (H. M. Pooley, F.-X. Abellan, and D. Karamata, J. Bacteriol. 174:646-649, 1992). Images PMID:7961496

Outcomes of support rod usage in loop stoma formation.

PubMed

Whiteley, Ian; Russell, Michael; Nassar, Natasha; Gladman, Marc A

2016-06-01

Traditionally, support rods have been used when creating loop stomas in the hope of preventing retraction. However, their effectiveness has not been clearly established. This study aimed to investigate the rate of stoma rod usage and its impact on stoma retraction and complication rates. A prospective cohort of 515 consecutive patients who underwent loop ileostomy/colostomy formation at a tertiary referral colorectal unit in Sydney, Australia were studied. Mortality and unplanned return to theatre rates were calculated. The primary outcome measure of interest was stoma retraction, occurring within 30 days of surgery. Secondary outcome measures included early stoma complications. The 10-year temporal trends for rod usage, stoma retraction, and complications were examined. Mortality occurred in 23 patients (4.1 %) and unplanned return to theatre in 4 patients (0.8 %). Stoma retraction occurred in four patients (0.78 %), all without rods. However, the rate of retraction was similar, irrespective of whether rods were used (P = 0.12). There was a significant decline in the use of rods during the study period (P < 0.001) but this was not associated with an increase in stoma retraction rates. Early complications occurred in 94/432 patients (21.8 %) and were more likely to occur in patients with rods (64/223 versus 30/209 without rods, P < 0.001). Stoma retraction is a rare complication and its incidence is not significantly affected by the use of support rods. Further, complications are common post-operatively, and the rate appears higher when rods are used. The routine use of rods warrants judicious application. WHAT DOES THIS PAPER ADD TO THE LITERATURE?: It remains unclear whether support rods prevent stoma retraction. This study, the largest to date, confirms that stoma retraction is a rare complication and is not significantly affected by the use of rods. Consequently, routine rod usage cannot be recommended, particularly as it is associated with increased stoma complications.

Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile

DOEpatents

Leung, Ka-Ngo; Gordon, K.C.; Kippenhan, D.O.; Purgalis, P.; Moussa, D.; Williams, M.D.; Wilde, S.B.; West, M.W.

1987-10-16

A large area directly heated lanthanum hexaboride (LaB/sub 6/) cathode system is disclosed. The system comprises a LaB/sub 6/ cathode element generally circular in shape about a central axis. The cathode element has a head with an upper substantially planar emission surface, and a lower downwardly and an intermediate body portion which diminishes in cross-section from the head towards the base of the cathode element. A central rod is connected to the base of the cathode element and extends along the central axis. Plural upstanding spring fingers are urged against an outer peripheral contact surface of the head end to provide a mechanical and electrical connection to the cathode element. 7 figs

Mirror mount

DOEpatents

Humpal, H.H.

1987-11-10

A mirror mount is provided that allows free pitch, yaw and roll motion of the mirror while keeping the location of a point on the surface of the mirror fixed in the rest frame of reference of the mount. Yaw movement is provided by two yaw cylinders that are bearing mounted to provide rotation. Pitch and roll motion is provided by a spherically annular shell that is air bearing mounted to move between a clamp and an upper pedestal bearing. The centers of curvature of the spherical surfaces of the shell lie upon the point. Pitch motion and roll motion are separately and independently imparted to mirror by a pair of pitch paddles and a pair of roll paddles that are independently and separately moved by control rods driven by motors. 5 figs.

Mirror mount

DOEpatents

Humpal, H.H.

1986-03-21

A mirror mount is provided that allows free pitch, yaw and roll motion of the mirror while keeping the location of a point on the surface of the mirror fixed in the rest frame of reference of the mount. Yaw movement is provided by two yaw cylinders that are bearing mounted to provide rotation. Pitch and roll motion is provided by a spherically annular shell that is air bearing mounted to move between a clamp and an upper pedestal bearing. The centers of curvature of the spherical surfaces of the shell lie upon the point. Pitch motion and roll motion are separately and independently imparted to mirror by a pair of pitch paddles and a pair of roll paddles that are independently and separately moved by control rods driven by motors.

Method and means of packaging nuclear fuel rods for handling

DOEpatents

Adam, Milton F.

1979-01-01

Nuclear fuel rods, especially spent nuclear fuel rods that may show physical distortion, are encased within a metallic enclosing structure by forming a tube about the fuel rod. The tube has previously been rolled to form an overlapping tubular structure and then unrolled and coiled about an axis perpendicular to the tube. The fuel rod is inserted into the tube as the rolled tube is removed from a coiled strip and allowed to reassume its tubular shape about the fuel rod. Rollers support the coiled strip in an open position as the coiled strip is uncoiled and allowed to roll about the fuel rod.

Variable flow control for a nuclear reactor control rod

DOEpatents

Carleton, Richard D.; Bhattacharyya, Ajay

1978-01-01

A variable flow control for a control rod assembly of a nuclear reactor that depends on turbulent friction though an annulus. The annulus is formed by a piston attached to the control rod drive shaft and a housing or sleeve fitted to the enclosure housing the control rod. As the nuclear fuel is burned up and the need exists for increased reactivity, the control rods are withdrawn, which increases the length of the annulus and decreases the rate of coolant flow through the control rod assembly.

Locked-wrap fuel rod

DOEpatents

Kaplan, Samuel; Chertock, Alan J.; Punches, James R.

1977-01-01

A method for spacing fast reactor fuel rods using a wire wrapper improved by orienting the wire-wrapped fuel rods in a unique manner which introduces desirable performance characteristics not attainable by previous wire-wrapped designs. Use of this method in a liquid metal fast breeder reactor results in: (a) improved mechanical performance, (b) improved rod-to-rod contact, (c) reduced steel volume, and (d) improved thermal-hydraulic performance. The method produces a "locked wrap" design which tends to lock the rods together at each of the wire cluster locations.

Lightning protection using energized Franklin rods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdel-Salam, M.; Al-Abdul-Latif, U.

1995-12-31

In this paper, the onset criterion of the upward streamers from an energized Franklin rod is formulated as a function of the geometry of the rod and the height and current of the downward leader. The electric field in the vicinity of the lightning rod is calculated using the charge simulation technique. The dependency of the radius of protection on the amplitude of the pulse voltage applied to Franklin rod, the downward leader current and the tip radius and height of the rod is investigated.

Leaf variations in Elaeagnus angustifolia related to environmental heterogeneity.

PubMed

Klich

2000-11-01

Elaeagnus angustifolia (Russian olive) is a Eurasian tree that has become naturalized and has invaded zones along watercourses in many arid and semiarid regions of the world. These habitats are characterized by vertical environmental gradients, thus trees must develop some plasticity to adapt to the wide range of site conditions. This study was undertaken to test the hypothesis that variations in leaf anatomy and morphology of E. angustifolia reflect their adaptability to the differences in the microclimate that occur within the canopy of single trees. Foliar architecture, blade and petiole epidermal and internal anatomy were examined in leaves at different canopy positions and related to environmental conditions. Upper sun-leaves are exposed to higher solar irradiance and lower air humidity and are smaller, more slender and thicker than the lower, half-exposed and shade-leaves. Color varies between the leaves at different levels, from silvery grey-green in the upper strata, to dark green in the lower one. Bicolor is more evident in half-exposed and shaded leaves. When compared with the lower half-exposed and shade-leaves, the upper leaves of E. angustifolia have a greater areole density, a higher mesophyll proportion and stomatal density. Trichomes are multicellular, pedestalled, stellate-branched or peltate and their form and density can be associated with leaf color and appearance. The slender petioles of the upper leaves have proportionally more epidermis, collenchyma and phloem and less parenchyma and xylem than those of lower leaves, when observed in transverse sections. Foliar morphological and anatomical variability in E. angustifolia may be considered an adaptive advantage that enables leaves to develop and function in habitats marked by strong variations of solar radiation, air temperature and humidity.

Structural Integrity Testing Method for PRSEUS Rod-Wrap Stringer Design

NASA Technical Reports Server (NTRS)

Wang, John T.; Grenoble, Ray W.; Pickell, Robert D.

2012-01-01

NASA Langley Research Center and The Boeing Company are developing an innovative composite structural concept, called PRSEUS, for the flat center section of a future environmentally friendly hybrid wing body (HWB) aircraft. The PRSEUS (Pultruded Rod Stitched Efficient Unitized Structure) concept uses dry textile preforms for the skins, frames, and stiffener webs. The highly loaded stiffeners are made from precured unidirectional carbon/epoxy rods and dry fiber preforms. The rods are wrapped with the dry fiber preforms and a resin infusion process is used to form the rod-wrap stiffeners. The structural integrity of the rod-wrap interface is critical for maintaining the panel s high strength and bending rigidity. No standard testing method exists for testing the strength of the rod-wrap bondline. Recently, Boeing proposed a rod push-out testing method and conducted some preliminary tests using this method. This paper details an analytical study of the rod-wrap bondline. The rod-wrap interface is modeled as a cohesive zone for studying the initiation and growth of interfacial debonding during push-out testing. Based on the correlations of analysis results and Boeing s test data, the adequacy of the rod-wrap testing method is evaluated, and potential approaches for improvement of the test method are proposed.

Optimization of a rod pinch diode radiography source at 2.3 MV

NASA Astrophysics Data System (ADS)

Menge, P. R.; Johnson, D. L.; Maenchen, J. E.; Rovang, D. C.; Oliver, B. V.; Rose, D. V.; Welch, D. R.

2003-08-01

Rod pinch diodes have shown considerable capability as high-brightness flash x-ray sources for penetrating dynamic radiography. The rod pinch diode uses a small diameter (0.4-2 mm) anode rod extended through a cathode aperture. When properly configured, the electron beam born off of the aperture edge can self-insulate and pinch onto the tip of the rod creating an intense, small x-ray source. Sandia's SABRE accelerator (2.3 MV, 40 Ω, 70 ns) has been utilized to optimize the source experimentally by maximizing the figure of merit (dose/spot diameter2) and minimizing the diode impedance droop. Many diode parameters have been examined including rod diameter, rod length, rod material, cathode aperture diameter, cathode thickness, power flow gap, vacuum quality, and severity of rod-cathode misalignment. The configuration producing the greatest figure of merit uses a 0.5 mm diameter gold rod, a 6 mm rod extension beyond the cathode aperture (diameter=8 mm), and a 10 cm power flow gap to produce up to 3.5 rad (filtered dose) at 1 m from a 0.85 mm x-ray on-axis spot (1.02 mm at 3° off axis). The resultant survey of parameter space has elucidated several physics issues that are discussed.

Ultrasonic Structural Health Monitoring to Assess the Integrity of Spinal Growing Rods In Vitro.

PubMed

Oetgen, Matthew E; Goodley, Addison; Yoo, Byungseok; Pines, Darryll J; Hsieh, Adam H

2016-01-01

Rod fracture is a common complication of growing rods and can result in loss of correction, patient discomfort, and unplanned revision surgery. The ability to quantitate rod integrity at each lengthening would be advantageous to avoid this complication. We investigate the feasibility of applying structural health monitoring to evaluate the integrity of growing rods in vitro. Single-rod titanium 4.5-mm growing rod constructs (n = 9), one screw proximally and one distally connected by in-line connectors, were assembled with pedicle screws fixed in polyethylene blocks. Proximal and distal ends were loaded and constructs subjected to cyclic axial compression (0-100 N at 1 Hz), with incrementally increasing maximum compressive loads of 10 N every 9k cycles until failure. Four piezoceramic transducers (PZTs) were mounted along the length the constructs to interrogate the integrity of the rods with an ultrasonic, guided lamb wave approach. Every 9k cycles, an 80 V excitatory voltage was applied to a PZT to generate high-frequency vibrations, which, after propagating through the construct, was detected by the remaining PZTs. Amplitude differences between pre- and postload waveform signals were calculated until rod failure. Average construct lifetime was 88,991 ± 13,398 cycles. All constructs failed due to rod fracture within 21 mm (mean = 15 ± 4.5 mm) of a screw or connector. Amplitude differences between pre- and postload increased in a stepwise fashion as constructs were cycled. Compared to baseline, we found a 1.8 ± 0.6-fold increase in amplitude 18k cycles before failure, a 2.2 ± 1.0-fold increase in amplitude 9k cycles before failure, and a 2.75 ± 1.5-fold increase in amplitude immediately before rod fracture. We describe a potential method for assessing the structural integrity of growing rods using ultrasonic structural health monitoring. These preliminary data demonstrate the ability of periodic rod assessment to detect structural changes in cycled growing rods, which appear to correspond to subclinical rod fatigue before rod fracture. Copyright © 2016 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.

75 FR 21658 - Carbon and Certain Alloy Steel Wire Rod From Trinidad and Tobago

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-26

... Certain Alloy Steel Wire Rod From Trinidad and Tobago AGENCY: United States International Trade Commission... Investigation No. 731-TA-961 concerning carbon and certain alloy steel wire rod (``wire rod'') from Trinidad and... of imports of wire rod from Trinidad and Tobago that were sold in the United States at less than fair...

78 FR 2658 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Rescission of Antidumping Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-14

... Steel Wire Rod From Mexico: Rescission of Antidumping Duty Administrative Review; 2011-2012 AGENCY... order on carbon and certain alloy steel wire rod (``wire rod'') from Mexico for the period October 1... order on wire rod from Mexico for the period of review, October 1, 2011, through September 30, 2012.\\1...

RodZ links MreB to cell wall synthesis to mediate MreB rotation and robust morphogenesis

PubMed Central

Morgenstein, Randy M.; Bratton, Benjamin P.; Nguyen, Jeffrey P.; Ouzounov, Nikolay; Shaevitz, Joshua W.; Gitai, Zemer

2015-01-01

The rod shape of most bacteria requires the actin homolog, MreB. Whereas MreB was initially thought to statically define rod shape, recent studies found that MreB dynamically rotates around the cell circumference dependent on cell wall synthesis. However, the mechanism by which cytoplasmic MreB is linked to extracytoplasmic cell wall synthesis and the function of this linkage for morphogenesis has remained unclear. Here we demonstrate that the transmembrane protein RodZ mediates MreB rotation by directly or indirectly coupling MreB to cell wall synthesis enzymes. Furthermore, we map the RodZ domains that link MreB to cell wall synthesis and identify mreB mutants that suppress the shape defect of ΔrodZ without restoring rotation, uncoupling rotation from rod-like growth. Surprisingly, MreB rotation is dispensable for rod-like shape determination under standard laboratory conditions but is required for the robustness of rod shape and growth under conditions of cell wall stress. PMID:26396257

RodZ links MreB to cell wall synthesis to mediate MreB rotation and robust morphogenesis.

PubMed

Morgenstein, Randy M; Bratton, Benjamin P; Nguyen, Jeffrey P; Ouzounov, Nikolay; Shaevitz, Joshua W; Gitai, Zemer

2015-10-06

The rod shape of most bacteria requires the actin homolog, MreB. Whereas MreB was initially thought to statically define rod shape, recent studies found that MreB dynamically rotates around the cell circumference dependent on cell wall synthesis. However, the mechanism by which cytoplasmic MreB is linked to extracytoplasmic cell wall synthesis and the function of this linkage for morphogenesis has remained unclear. Here we demonstrate that the transmembrane protein RodZ mediates MreB rotation by directly or indirectly coupling MreB to cell wall synthesis enzymes. Furthermore, we map the RodZ domains that link MreB to cell wall synthesis and identify mreB mutants that suppress the shape defect of ΔrodZ without restoring rotation, uncoupling rotation from rod-like growth. Surprisingly, MreB rotation is dispensable for rod-like shape determination under standard laboratory conditions but is required for the robustness of rod shape and growth under conditions of cell wall stress.

Final report, PT IP-535-C: Test of smaller VSR`s in DR reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vaughn, A.D.

1963-04-17

Because of rod-sticking problems at DR Reactor, a knuckle rod of B Reactor design was installed in vertical safety channel number 28. The substitute VSR, which has a smaller diameter than the original DR rod, has been tested for its operational feasibility including both drop time and reactivity effect. The reactivity effect of the rod was estimated by comparison of the reactivity transient caused by insertion of the specific B-type rod after scramming into the pile, with similar transients caused by normal vertical safety rod in an adjacent channel. This document lists the indicated relative control strength of the rodmore » as an empirical basis for future safety calculations. Results indicate that the B-type knuckel rod in DR reactor is about 80% as strong as a normal DR vertical safety rod if used in equivalent flux distribution and location; this makes it reasonable to assume that the local control strength of the B-type knuckel rod is 98 {mu}b.« less

Techniques and equipment for assessing the structural integrity of subterranean tower anchor rods

DOEpatents

Hinz, William R.; Parker, Matthew J.

2001-01-01

Techniques and equipment for evaluating structural integrity of buried anchor rods in situ are disclosed. The techniques avoid excavation of soil and avoid, or at least reduce, the possibility of damage to the rods or the concrete in which they may be embedded when evaluations are conducted. Instead, ultrasonic energy is transmitted through the rod from a portable transducer, and returned energy (in either or both of direct and mode-converted states) may be analyzed to assist in detecting flaws, corrosion, wastage, or other degradation of the rod. Data from a field evaluation may be compared with baseline data maintained either for a specific rod or for rods of similar composition and length (or both), and periodic field evaluations of a rod may be used to analyze trends in its structure over time.

Developing Tests of Visual Dependency

NASA Technical Reports Server (NTRS)

Kindrat, Alexandra N.

2011-01-01

Astronauts develop neural adaptive responses to microgravity during space flight. Consequently these adaptive responses cause maladaptive disturbances in balance and gait function when astronauts return to Earth and are re-exposed to gravity. Current research in the Neuroscience Laboratories at NASA-JSC is focused on understanding how exposure to space flight produces post-flight disturbances in balance and gait control and developing training programs designed to facilitate the rapid recovery of functional mobility after space flight. In concert with these disturbances, astronauts also often report an increase in their visual dependency during space flight. To better understand this phenomenon, studies were conducted with specially designed training programs focusing on visual dependency with the aim to understand and enhance subjects ability to rapidly adapt to novel sensory situations. The Rod and Frame test (RFT) was used first to assess an individual s visual dependency, using a variety of testing techniques. Once assessed, subjects were asked to perform two novel tasks under transformation (both the Pegboard and Cube Construction tasks). Results indicate that head position cues and initial visual test conditions had no effect on an individual s visual dependency scores. Subjects were also able to adapt to the manual tasks after several trials. Individual visual dependency correlated with ability to adapt manual to a novel visual distortion only for the cube task. Subjects with higher visual dependency showed decreased ability to adapt to this task. Ultimately, it was revealed that the RFT may serve as an effective prediction tool to produce individualized adaptability training prescriptions that target the specific sensory profile of each crewmember.

CONTROL RODS FOR NUCLEAR REACTORS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bell, F.R.

1963-01-16

A means for controlling the control rod in emergency, when it is desired to shutdown the reactor with the shortest possible delay, is described. When the emergency occurs the control rod is allowed to drop freely under gravity from the control rod support tube into the bore in the reactor core. A normal shutdown is reached almost at the lowest rod position. In the shut-down position and also below it, the control rod had its full effect of reducing the level of activity in the core. When the shut-down position was reached, a brake came into action to decelerate themore » rod and reduce shock and the likelihood of damage. (C.E.S.)« less

Upper-Limb Rehabilitation With Adaptive Video Games for Preschool Children With Developmental Disabilities.

PubMed

Hsieh, Hsieh-Chun; Lin, Hung-Yu; Chiu, Wen-Hsin; Meng, Ling Fu; Liu, Chun Kai

2015-01-01

This study used a novel device to make video games accessible to children with developmental disabilities (DD) by modifying the training software and interfaces to enhance motor training. In the pretest-posttest design, 20 children (13 boys, 7 girls; mean age=5.2 yr) with DD received adaptive upper-limb motor rehabilitation consisting of fifteen 30-min individual sessions 3 times per week for 5 wk. Improvement in Beery-Buktenica Developmental Test of Visual Motor Integration and Peabody Developmental Motor Scales, Second Edition, scores for children with DD indicated significant differences between pretest and posttest. The rehabilitation device modified for the needs of children with DD is effective in improving visual-motor performance of children with DD. Copyright © 2015 by the American Occupational Therapy Association, Inc.

CRDM with separate SCRAM latch engagement and locking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dodd, Christopher D.; DeSantis, Paul K.; Stambaugh, Kevin J.

A control rod drive mechanism (CRDM) configured to latch onto the lifting rod of a control rod assembly and including separate latch engagement and latch holding mechanisms. A CRDM configured to latch onto the lifting rod of a control rod assembly and including a four-bar linkage closing the latch, wherein the four-bar linkage biases the latch closed under force of gravity.

77 FR 13545 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Notice of Final Results of Antidumping Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-07

... Steel Wire Rod From Mexico: Notice of Final Results of Antidumping Duty Administrative Review AGENCY... results of the administrative review of the antidumping duty order on carbon and certain alloy steel wire rod (wire rod) from Mexico.\\1\\ This review covers imports of wire rod from ArcelorMittal Las Truchas...

78 FR 63450 - Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-24

...-805, A-274-804, A-823-812] Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico... on carbon and certain alloy steel wire rod (``wire rod'') from Brazil, Indonesia, Mexico, Moldova... published the notice of initiation of the sunset reviews of the antidumping duty orders on wire rod from...

Summary report, Flexible VSR`s and VSR channel sleeve development programs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kempf, F.J.

1963-11-15

(VSR = vertical safety rod.) This report summarizes results of development programs which have evaluated vertical rod channel sleeving materials and provided flexible vertical rods, acceptable for both interim use before rod channel sleeving, and for subsequent use in sleeved channels. B{sub 4}C is the rod material; graphite and Al oxide are among the sleeve materials.

[Experimental study of recovery force of surface-modified TiNi memory alloy rod].

PubMed

Wang, Aiyuan; Peng, Jiang; Zhang, Xian; Xu, Wenjin; Wang, Xing; Sun, Minxue; Lu, Shibi

2006-08-01

The recovery force of Ti-Nb coated and uncoated TiNi shape memory alloy rods was investigated. The rods were 6.0 mm, 6.5 mm and 7.0 mm in diameter respectively. The mean transition temperature was 33.0 degrees C. The rods were stored at -18 degrees C and pre-bent with a three-point bending fixture, the span was 20. 0 centimeters and the deflections were 5.0 mm, 10.0 mm, 15.0 mm and 20.0 mm, respectively. The rods were then heated in a constant temperature saline solution chamber. The experimental temperature was 37.0 C and 50.0 C respectively. The recovery force was measured in a constant displacement mode on biomaterial test machine. The results showed that the recovery force of the memory alloy rod increased with increasing recovery temperature, rod diameter and deformation of both Ti-Nb coated and uncoated surface. The recovery force of Ti-Nb coated rods of 6.0 and 6.5 millimeter in diameter was lower than the uncoated rods in the same diameter. However, the recovery force of 7.0-mm-diameter rods showed no significant difference between coated and uncoated surface.

Experimental Study on Surrogate Nuclear Fuel Rods under Reversed Cyclic Bending

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hong; Wang, Jy-An John

The mechanical behavior of spent nuclear fuel (SNF) rods under reversed cyclic bending or bending fatigue must be understood to evaluate their vibration integrity in a transportation environment. This is especially important for high-burnup fuels (>45 GWd/MTU), which have the potential for increased structural damage. It has been demonstrated that the bending fatigue of SNF rods can be effectively studied using surrogate rods. In this investigation, surrogate rods made of stainless steel (SS) 304 cladding and aluminum oxide pellets were tested under load or moment control at a variety of amplitude levels at 5 Hz using the Cyclic Integrated Reversible-Bendingmore » Fatigue Tester developed at Oak Ridge National Laboratory. The behavior of the rods was further characterized using flexural rigidity and hysteresis data, and fractography was performed on the failed rods. The proposed surrogate rods captured many of the characteristics of deformation and failure mode observed in SNF, including the linear-to-nonlinear deformation transition and large residual curvature in static tests, PPI and PCMI failure mechanisms, and large variation in the initial structural condition. Rod degradation was measured and characterized by measuring the flexural rigidity; the degradation of the rigidity depended on both the moment amplitude applied and the initial structural condition of the rods. It was also shown that a cracking initiation site can be located on the internal surface or the external surface of cladding. Finally, fatigue damage to the bending rods can be described in terms of flexural rigidity, and the fatigue life of rods can be predicted once damage model parameters are properly evaluated. The developed experimental approach, test protocol, and analysis method can be used to study the vibration integrity of SNF rods in the future.« less

3D Imaging of Retinal Pigment Epithelial Cells in the Living Human Retina

PubMed Central

Liu, Zhuolin; Kocaoglu, Omer P.; Miller, Donald T.

2016-01-01

Purpose Dysfunction of the retinal pigment epithelium (RPE) underlies numerous retinal pathologies, but biomarkers sensitive to RPE change at the cellular level are limited. In this study, we used adaptive optics optical coherence tomography (AO-OCT) in conjunction with organelle motility as a novel contrast mechanism to visualize RPE cells and characterize their 3-dimensional (3D) reflectance profile. Methods Using the Indiana AO-OCT imaging system (λc = 790 nm), volumes were acquired in the macula of six normal subjects (25–61 years). Volumes were registered in 3D with subcellular accuracy, layers segmented, and RPE and photoreceptor en face images extracted and averaged. Voronoi and two-dimensional (2D) power spectra analyses were applied to the images to quantify RPE and cone packing and cone-to-RPE ratio. Results Adaptive optics OCT revealed two distinct reflectance patterns at the depth of the RPE. One is characterized by the RPE interface with rod photoreceptor tips, the second by the RPE cell nuclei and surrounding organelles, likely melanin. Increasing cell contrast by averaging proved critical for observing the RPE cell mosaic, successful in all subjects and retinal eccentricities imaged. Retinal pigment epithelium mosaic packing and cell thickness generally agreed with that of histology and in vivo studies using other imaging modalities. Conclusions We have presented, to our knowledge, the first detailed characterization of the 3D reflectance profile of individual RPE cells and their relation to cones and rods in the living human retina. Success in younger and older eyes establishes a path for testing aging effects in larger populations. Because the technology is based on OCT, our measurements will aid in interpreting clinical OCT images. PMID:27472277

Transducin Duplicates in the Zebrafish Retina and Pineal Complex: Differential Specialisation after the Teleost Tetraploidisation

PubMed Central

Lagman, David; Callado-Pérez, Amalia; Franzén, Ilkin E.

2015-01-01

Gene duplications provide raw materials that can be selected for functional adaptations by evolutionary mechanisms. We describe here the results of 350 million years of evolution of three functionally related gene families: the alpha, beta and gamma subunits of transducins, the G protein involved in vision. Early vertebrate tetraploidisations resulted in separate transducin heterotrimers: gnat1/gnb1/gngt1 for rods, and gnat2/gnb3/gngt2 for cones. The teleost-specific tetraploidisation generated additional duplicates for gnb1, gnb3 and gngt2. We report here that the duplicates have undergone several types of subfunctionalisation or neofunctionalisation in the zebrafish. We have found that gnb1a and gnb1b are co-expressed at different levels in rods; gnb3a and gnb3b have undergone compartmentalisation restricting gnb3b to the dorsal and medial retina, however, gnb3a expression was detected only at very low levels in both larvae and adult retina; gngt2b expression is restricted to the dorsal and medial retina, whereas gngt2a is expressed ventrally. This dorsoventral distinction could be an adaptation to protect the lower part of the retina from intense light damage. The ontogenetic analysis shows earlier onset of expression in the pineal complex than in the retina, in accordance with its earlier maturation. Additionally, gnb1a but not gnb1b is expressed in the pineal complex, and gnb3b and gngt2b are transiently expressed in the pineal during ontogeny, thus showing partial temporal subfunctionalisation. These retina-pineal distinctions presumably reflect their distinct functional roles in vision and circadian rhythmicity. In summary, this study describes several functional differences between transducin gene duplicates resulting from the teleost-specific tetraploidisation. PMID:25806532

Cone-like rhodopsin expressed in the all-cone retina of the colubrid pine snake as a potential adaptation to diurnality.

PubMed

Bhattacharyya, Nihar; Darren, Benedict; Schott, Ryan K; Tropepe, Vincent; Chang, Belinda S W

2017-07-01

Colubridae is the largest and most diverse family of snakes, with visual systems that reflect this diversity, encompassing a variety of retinal photoreceptor organizations. The transmutation theory proposed by Walls postulates that photoreceptors could evolutionarily transition between cell types in squamates, but few studies have tested this theory. Recently, evidence for transmutation and rod-like machinery in an all-cone retina has been identified in a diurnal garter snake ( Thamnophis ), and it appears that the rhodopsin gene at least may be widespread among colubrid snakes. However, functional evidence supporting transmutation beyond the existence of the rhodopsin gene remains rare. We examined the all-cone retina of another colubrid, Pituophis melanoleucus , thought to be more secretive/burrowing than Thamnophis We found that P. melanoleucus expresses two cone opsins (SWS1, LWS) and rhodopsin (RH1) within the eye. Immunohistochemistry localized rhodopsin to the outer segment of photoreceptors in the all-cone retina of the snake and all opsin genes produced functional visual pigments when expressed in vitro Consistent with other studies, we found that P. melanoleucus rhodopsin is extremely blue-shifted. Surprisingly, P. melanoleucus rhodopsin reacted with hydroxylamine, a typical cone opsin characteristic. These results support the idea that the rhodopsin-containing photoreceptors of P. melanoleucus are the products of evolutionary transmutation from rod ancestors, and suggest that this phenomenon may be widespread in colubrid snakes. We hypothesize that transmutation may be an adaptation for diurnal, brighter-light vision, which could result in increased spectral sensitivity and chromatic discrimination with the potential for colour vision. © 2017. Published by The Company of Biologists Ltd.

ELECTROMAGNETIC APPARATUS FOR MOVING A ROD

DOEpatents

Young, J.N.

1958-04-22

An electromagnetic apparatus for moving a rod-like member in small steps in either direction is described. The invention has particular application in the reactor field where the reactor control rods must be moved only a small distance and where the use of mechanical couplings is impractical due to the high- pressure seals required. A neutron-absorbing rod is mounted in a housing with gripping uaits that engage the rod, and coils for magnetizing the gripping units to make them grip, shift, and release the rod are located outside the housing.

CONTROL ROD DRIVE

DOEpatents

Chapellier, R.A.; Rogers, I.

1961-06-27

Accurate and controlled drive for the control rod is from an electric motor. A hydraulic arrangement is provided to balance a piston against which a control rod is urged by the application of fluid pressure. The electric motor drive of the control rod for normal operation is made through the aforementioned piston. In the event scramming is required, the fluid pressure urging the control rod against the piston is relieved and an opposite fluid pressure is applied. The lack of mechanical connection between the electric motor and control rod facilitates the scramming operation.

CONTROL SYSTEM FOR NEUTRONIC REACTORS

DOEpatents

Crever, F.E.

1962-05-01

BS>A slow-acting shim rod for control of major variations in reactor neutron flux and a fast-acting control rod to correct minor flux variations are employed to provide a sensitive, accurate control system. The fast-acting rod is responsive to an error signal which is produced by changes in the neutron flux from a predetermined optimum level. When the fast rod is thus actuated in a given direction, means is provided to actuate the slow-moving rod in that direction to return the fast rod to a position near the midpoint of its control range. (AEC)

Touch Locating and Stretch Sensing Studies of Conductive Hydrogels with Applications to Soft Robots.

PubMed

Zhou, Yanmin; He, Bin; Yan, Zhe; Shang, Yinghui; Wang, Qigang; Wang, Zhipeng

2018-02-13

Soft robots possess great potential in environmental adaptations, while their environmental sensing abilities are critical. Conductive hydrogels have been suggested to possess sensing abilities. However, their application in soft robots is lacking. In this work, we fabricated a soft and stretchable gel material, introduced its sensing mechanisms, and developed a measurement setup. Both experimental and simulation studies indicate strong nonlinearity of touch locating on a square touch panel with Cartesian coordinates. To simplify the touch locating, we proposed a touch locating system based on round touch panels with polar coordinates. Mathematical calculations and finite element method (FEM) simulations showed that in this system the locating of a touch point was only determined by its polar radius. This was verified by experimental studies. As a resistor, a gel strip's resistance increases with stretching. To demonstrate their applications on soft robots, a 3D printed three-fingered soft gripper was employed with gel strips attached. During finger bending for rod grasping, the resistances of the gel strips increased, indicating stretching of the soft material. Furthermore, the strain and stress of a gel strip increased with a decrease of the rod diameter. These studies advance the application of conductive hydrogels on soft robots.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paulauskas, Tadas; Buurma, Christopher; Colegrove, Eric

Dislocation cores have long dominated the electronic and optical behaviors of semiconductor devices and detailed atomic characterization is required to further explore their effects. Miniaturization of semiconductor devices to nanometre scale also puts emphasis on a material's mechanical properties to withstand failure due to processing or operational stresses. Sessile junctions of dislocations provide barriers to propagation of mobile dislocations and may lead to work-hardening. The sessile Lomer–Cottrell and Hirth lock dislocations, two stable lowest elastic energy stair-rods, are studied in this paper. More specifically, using atomic resolution high-angle annular dark-field imaging and atomic-column-resolved X-ray spectrum imaging in an aberration-corrected scanningmore » transmission electron microscope, dislocation core structures are examined in zinc-blende CdTe. A procedure is outlined for atomic scale analysis of dislocation junctions which allows determination of their identity with specially tailored Burgers circuits and also formation mechanisms of the polar core structures based on Thompson's tetrahedron adapted to reactions of polar dislocations as they appear in CdTe and other zinc-blende solids. Strain fields associated with the dislocations calculatedviageometric phase analysis are found to be diffuse and free of `hot spots' that reflect compact structures and low elastic energy of the pure-edge stair-rods.« less

Calcium-induced calcium release in rod photoreceptor terminals boosts synaptic transmission during maintained depolarization

PubMed Central

Cadetti, Lucia; Bryson, Eric J.; Ciccone, Cory A.; Rabl, Katalin; Thoreson, Wallace B.

2008-01-01

We examined the contribution of calcium-induced calcium release (CICR) to synaptic transmission from rod photoreceptor terminals. Whole-cell recording and confocal calcium imaging experiments were conducted on rods with intact synaptic terminals in a retinal slice preparation from salamander. Low concentrations of ryanodine stimulated calcium increases in rod terminals, consistent with the presence of ryanodine receptors. Application of strong depolarizing steps (−70 to −10 mV) exceeding 200 ms or longer in duration evoked a wave of calcium that spread across the synaptic terminals of voltage-clamped rods. This secondary calcium increase was blocked by high concentrations of ryanodine, indicating it was due to CICR. Ryanodine (50 μM) had no significant effect on rod calcium current (Ica) although it slightly diminished rod light-evoked voltage responses. Bath application of 50 μM ryanodine strongly inhibited light-evoked currents in horizontal cells. Whether applied extracellularly or delivered into the rod cell through the patch pipette, ryanodine (50 μM) also inhibited excitatory post-synaptic currents (EPSCs) evoked in horizontal cells by depolarizing steps applied to rods. Ryanodine caused a preferential reduction in the later portions of EPSCs evoked by depolarizing steps of 200 ms or longer. These results indicate that CICR enhances calcium increases in rod terminals evoked by sustained depolarization, which in turn acts to boost synaptic exocytosis from rods. PMID:16819987

The effect of different screw-rod design on the anti-rotational torque: a biomechanical comparison of three conventional screw-rod constructs.

PubMed

Huang, Zifang; Wang, Chongwen; Fan, Hengwei; Sui, Wenyuan; Li, Xueshi; Wang, Qifei; Yang, Junlin

2017-07-28

Screw-rod constructs have been widely used to correct spinal deformities, but the effects of different screw-rod systems on anti-rotational torque have not been determined. This study aimed to analyze the biomechanical effect of different rod-screw constructs on anti-rotational torque. Three conventional spinal screw-rod systems (Legacy, RF-F-10 and USSII) were used to test the anti-rotational torque in the material test machine. ANOVA was performed to evaluate the anti-rotational capacity of different pedicle screws-rod constructs. The anti-rotational torque of Legacy group, RF-F-10 group and USSII group were 12.3 ± 1.9 Nm, 6.8 ± 0.4 Nm, and 3.9 ± 0.8 Nm, with a P value lower than 0.05. This results indicated that the Legacy screws-rod construct could provide a highest anti-rotation capacity, which is 68% and 210% greater than RF-F-10 screw-rod construct and USSII screw-rod respectively. The anti-rotational torque may be mainly affected by screw cap and groove design. Our result showed the anti-rotational torque are: Legacy system > RF-F-10 system > USSII system, suggesting that appropriate rod-screw constructs selection in surgery may be vital for anti-rotational torque improvement and preventing derotation correction loss.

Mantle structure beneath Africa and Arabia from adaptively parameterized P-wave tomography: Implications for the origin of Cenozoic Afro-Arabian tectonism

NASA Astrophysics Data System (ADS)

Hansen, Samantha E.; Nyblade, Andrew A.; Benoit, Margaret H.

2012-02-01

While the Cenozoic Afro-Arabian Rift System (AARS) has been the focus of numerous studies, it has long been questioned if low-velocity anomalies in the upper mantle beneath eastern Africa and western Arabia are connected, forming one large anomaly, and if any parts of the anomalous upper mantle structure extend into the lower mantle. To address these questions, we have developed a new image of P-wave velocity variations in the Afro-Arabian mantle using an adaptively parameterized tomography approach and an expanded dataset containing travel-times from earthquakes recorded on many new temporary and permanent seismic networks. Our model shows a laterally continuous, low-velocity region in the upper mantle beneath all of eastern Africa and western Arabia, extending to depths of ~ 500-700 km, as well as a lower mantle anomaly beneath southern Africa that rises from the core-mantle boundary to at least ~ 1100 km depth and possibly connects to the upper mantle anomaly across the transition zone. Geodynamic models which invoke one or more discrete plumes to explain the origin of the AARS are difficult to reconcile with the lateral and depth extent of the upper mantle low-velocity region, as are non-plume models invoking small-scale convection passively induced by lithospheric extension or by edge-flow around thick cratonic lithosphere. Instead, the low-velocity anomaly beneath the AARS can be explained by the African superplume model, where the anomalous upper mantle structure is a continuation of a large, thermo-chemical upwelling in the lower mantle beneath southern Africa. These findings provide further support for a geodynamic connection between processes in Earth's lower mantle and continental break-up within the AARS.

Closed-Loop Neuroprosthesis for Reach-to-Grasp Assistance: Combining Adaptive Multi-channel Neuromuscular Stimulation with a Multi-joint Arm Exoskeleton.

PubMed

Grimm, Florian; Gharabaghi, Alireza

2016-01-01

Stroke patients with severe motor deficits cannot execute task-oriented rehabilitation exercises with their affected upper extremity. Advanced rehabilitation technology may support them in performing such reach-to-grasp movements. The challenge is, however, to provide assistance as needed, while maintaining the participants' commitment during the exercises. In this feasibility study, we introduced a closed-loop neuroprosthesis for reach-to-grasp assistance which combines adaptive multi-channel neuromuscular stimulation with a multi-joint arm exoskeleton. Eighteen severely affected chronic stroke patients were assisted by a gravity-compensating, seven-degree-of-freedom exoskeleton which was attached to the paretic arm for performing reach-to-grasp exercises resembling activities of daily living in a virtual environment. During the exercises, adaptive electrical stimulation was applied to seven different muscles of the upper extremity in a performance-dependent way to enhance the task-oriented movement trajectory. The stimulation intensity was individualized for each targeted muscle and remained subthreshold, i.e., induced no overt support. Closed-loop neuromuscular stimulation could be well integrated into the exoskeleton-based training, and increased the task-related range of motion (p = 0.0004) and movement velocity (p = 0.015), while preserving accuracy. The highest relative stimulation intensity was required to facilitate the grasping function. The facilitated range of motion correlated with the upper extremity Fugl-Meyer Assessment score of the patients (p = 0.028). Combining adaptive multi-channel neuromuscular stimulation with antigravity assistance amplifies the residual motor capabilities of severely affected stroke patients during rehabilitation exercises and may thus provide a customized training environment for patient-tailored support while preserving the participants' engagement.

Closed-Loop Neuroprosthesis for Reach-to-Grasp Assistance: Combining Adaptive Multi-channel Neuromuscular Stimulation with a Multi-joint Arm Exoskeleton

PubMed Central

Grimm, Florian; Gharabaghi, Alireza

2016-01-01

Stroke patients with severe motor deficits cannot execute task-oriented rehabilitation exercises with their affected upper extremity. Advanced rehabilitation technology may support them in performing such reach-to-grasp movements. The challenge is, however, to provide assistance as needed, while maintaining the participants' commitment during the exercises. In this feasibility study, we introduced a closed-loop neuroprosthesis for reach-to-grasp assistance which combines adaptive multi-channel neuromuscular stimulation with a multi-joint arm exoskeleton. Eighteen severely affected chronic stroke patients were assisted by a gravity-compensating, seven-degree-of-freedom exoskeleton which was attached to the paretic arm for performing reach-to-grasp exercises resembling activities of daily living in a virtual environment. During the exercises, adaptive electrical stimulation was applied to seven different muscles of the upper extremity in a performance-dependent way to enhance the task-oriented movement trajectory. The stimulation intensity was individualized for each targeted muscle and remained subthreshold, i.e., induced no overt support. Closed-loop neuromuscular stimulation could be well integrated into the exoskeleton-based training, and increased the task-related range of motion (p = 0.0004) and movement velocity (p = 0.015), while preserving accuracy. The highest relative stimulation intensity was required to facilitate the grasping function. The facilitated range of motion correlated with the upper extremity Fugl-Meyer Assessment score of the patients (p = 0.028). Combining adaptive multi-channel neuromuscular stimulation with antigravity assistance amplifies the residual motor capabilities of severely affected stroke patients during rehabilitation exercises and may thus provide a customized training environment for patient-tailored support while preserving the participants' engagement. PMID:27445658

Exploring the bases for a mixed reality stroke rehabilitation system, Part II: design of interactive feedback for upper limb rehabilitation.

PubMed

Lehrer, Nicole; Chen, Yinpeng; Duff, Margaret; L Wolf, Steven; Rikakis, Thanassis

2011-09-08

Few existing interactive rehabilitation systems can effectively communicate multiple aspects of movement performance simultaneously, in a manner that appropriately adapts across various training scenarios. In order to address the need for such systems within stroke rehabilitation training, a unified approach for designing interactive systems for upper limb rehabilitation of stroke survivors has been developed and applied for the implementation of an Adaptive Mixed Reality Rehabilitation (AMRR) System. The AMRR system provides computational evaluation and multimedia feedback for the upper limb rehabilitation of stroke survivors. A participant's movements are tracked by motion capture technology and evaluated by computational means. The resulting data are used to generate interactive media-based feedback that communicates to the participant detailed, intuitive evaluations of his performance. This article describes how the AMRR system's interactive feedback is designed to address specific movement challenges faced by stroke survivors. Multimedia examples are provided to illustrate each feedback component. Supportive data are provided for three participants of varying impairment levels to demonstrate the system's ability to train both targeted and integrated aspects of movement. The AMRR system supports training of multiple movement aspects together or in isolation, within adaptable sequences, through cohesive feedback that is based on formalized compositional design principles. From preliminary analysis of the data, we infer that the system's ability to train multiple foci together or in isolation in adaptable sequences, utilizing appropriately designed feedback, can lead to functional improvement. The evaluation and feedback frameworks established within the AMRR system will be applied to the development of a novel home-based system to provide an engaging yet low-cost extension of training for longer periods of time.

Exploring the bases for a mixed reality stroke rehabilitation system, Part II: Design of Interactive Feedback for upper limb rehabilitation

PubMed Central

2011-01-01

Background Few existing interactive rehabilitation systems can effectively communicate multiple aspects of movement performance simultaneously, in a manner that appropriately adapts across various training scenarios. In order to address the need for such systems within stroke rehabilitation training, a unified approach for designing interactive systems for upper limb rehabilitation of stroke survivors has been developed and applied for the implementation of an Adaptive Mixed Reality Rehabilitation (AMRR) System. Results The AMRR system provides computational evaluation and multimedia feedback for the upper limb rehabilitation of stroke survivors. A participant's movements are tracked by motion capture technology and evaluated by computational means. The resulting data are used to generate interactive media-based feedback that communicates to the participant detailed, intuitive evaluations of his performance. This article describes how the AMRR system's interactive feedback is designed to address specific movement challenges faced by stroke survivors. Multimedia examples are provided to illustrate each feedback component. Supportive data are provided for three participants of varying impairment levels to demonstrate the system's ability to train both targeted and integrated aspects of movement. Conclusions The AMRR system supports training of multiple movement aspects together or in isolation, within adaptable sequences, through cohesive feedback that is based on formalized compositional design principles. From preliminary analysis of the data, we infer that the system's ability to train multiple foci together or in isolation in adaptable sequences, utilizing appropriately designed feedback, can lead to functional improvement. The evaluation and feedback frameworks established within the AMRR system will be applied to the development of a novel home-based system to provide an engaging yet low-cost extension of training for longer periods of time. PMID:21899779

Simultaneous double-rod rotation technique in posterior instrumentation surgery for correction of adolescent idiopathic scoliosis.

PubMed

Ito, Manabu; Abumi, Kuniyoshi; Kotani, Yoshihisa; Takahata, Masahiko; Sudo, Hideki; Hojo, Yoshihiro; Minami, Akio

2010-03-01

The authors present a new posterior correction technique consisting of simultaneous double-rod rotation using 2 contoured rods and polyaxial pedicle screws with or without Nesplon tapes. The purpose of this study is to introduce the basic principles and surgical procedures of this new posterior surgery for correction of adolescent idiopathic scoliosis. Through gradual rotation of the concave-side rod by 2 rod holders, the convex-side rod simultaneously rotates with the the concave-side rod. This procedure does not involve any force pushing down the spinal column around the apex. Since this procedure consists of upward pushing and lateral translation of the spinal column with simultaneous double-rod rotation maneuvers, it is simple and can obtain thoracic kyphosis as well as favorable scoliosis correction. This technique is applicable not only to a thoracic single curve but also to double major curves in cases of adolescent idiopathic scoliosis.

Measurements of lightning rod responses to nearby strikes

NASA Astrophysics Data System (ADS)

Moore, C. B.; Aulich, G. D.; Rison, W.

2000-05-01

Following Benjamin Franklin's invention of the lightning rod, based on his discovery that electrified objects could be discharged by approaching them with a metal needle in hand, conventional lightning rods in the U.S. have had sharp tips. In recent years, the role of the sharp tip in causing a lightning rod to act as a strike receptor has been questioned leading to experiments in which pairs of various sharp-tipped and blunt rods have been exposed beneath thunderclouds to determine the better strike receptor. After seven years of tests, none of the sharp Franklin rods or of the so-called “early streamer emitters” has been struck, but 12 blunt rods with tip diameters ranging from 12.7 mm to 25.4 mm have taken strikes. Our field experiments and our analyses indicate that the strike-reception probabilities of Franklin's rods are greatly increased when their tips are made moderately blunt.

Effective Dynamic Range and Retest Reliability of Dark-Adapted Two-Color Fundus-Controlled Perimetry in Patients With Macular Diseases.

PubMed

Pfau, Maximilian; Lindner, Moritz; Müller, Philipp L; Birtel, Johannes; Finger, Robert P; Harmening, Wolf M; Fleckenstein, Monika; Holz, Frank G; Schmitz-Valckenberg, Steffen

2017-05-01

To determine the effective dynamic range (EDR), retest reliability, and number of discriminable steps (DS) for mesopic and dark-adapted two-color fundus-controlled perimetry (FCP) using the S-MAIA (Scotopic-Macular Integrity Assessment) "micro-perimeter." In this prospective cross-sectional study, each of the 52 eyes of 52 subjects with various macular diseases (mean age 62.0 ± 16.9 years; range, 19.1-90.1 years) underwent duplicate mesopic (achromatic stimuli, 400-800 nm), dark-adapted cyan (505 nm), and dark-adapted red (627 nm) FCP using a grid of 61 stimuli covering 18° of the central retina. The EDR, the number of DS, and the retest reliability for point-wise sensitivity (PWS) were analyzed. The effects of fixation stability, sensitivity, and age on retest reliability were examined using mixed-effects models. The EDR was 10 to 30 dB with five DS for mesopic and 4 to 17 dB with four DS for dark-adapted cyan and red testing. PWS retest reliability was good among all three types of retinal sensitivity assessments (coefficient of repeatability ±5.79, ±4.72, and ±4.77 dB, respectively) and did not depend on fixation stability or age. PWS had no effect on retest variability in dark-adapted cyan and dark-adapted red testing but had a minor effect in mesopic testing. Combined mesopic and dark-adapted two-color FCP allows for reliable topographic testing of cone and rod function in patients with various macular diseases with and without foveal fixation. Retest reliability is homogeneous across eccentricities and various degrees of scotoma depth, including zones at risk for disease progression. These reliability estimates can serve for the design of future clinical trials.

Fuel bundle design for enhanced usage of plutonium fuel

DOEpatents

Reese, Anthony P.; Stachowski, Russell E.

1995-01-01

A nuclear fuel bundle includes a square array of fuel rods each having a concentration of enriched uranium and plutonium. Each rod of an interior array of the rods also has a concentration of gadolinium. The interior array of rods is surrounded by an exterior array of rods void of gadolinium. By this design, usage of plutonium in the nuclear reactor is enhanced.

Fuel bundle design for enhanced usage of plutonium fuel

DOEpatents

Reese, A.P.; Stachowski, R.E.

1995-08-08

A nuclear fuel bundle includes a square array of fuel rods each having a concentration of enriched uranium and plutonium. Each rod of an interior array of the rods also has a concentration of gadolinium. The interior array of rods is surrounded by an exterior array of rods void of gadolinium. By this design, usage of plutonium in the nuclear reactor is enhanced. 10 figs.

Linear motion device and method for inserting and withdrawing control rods

DOEpatents

Smith, Jay E.

1984-01-01

A linear motion device, more specifically a control rod drive mechanism (CRDM) for inserting and withdrawing control rods into a reactor core, is capable of independently and sequentially positioning two sets of control rods with a single motor stator and rotor. The CRDM disclosed can control more than one control rod lead screw without incurring a substantial increase in the size of the mechanism.

Fretting corrosion behavior of nitinol spinal rods in conjunction with titanium pedicle screws.

PubMed

Lukina, Elena; Kollerov, Mikhail; Meswania, Jay; Khon, Alla; Panin, Pavel; Blunn, Gordon W

2017-03-01

Untypical corrosion damage including erosions combined with the build-up of titanium oxide as a corrosion product on the surface of explanted Nitinol spinal rods in the areas where it was in contact with titanium pedicle screw head is reported. It was suggested that Nitinol rods might have inferior fretting corrosion resistance compared with that made of titanium or CoCr. Fretting corrosion of Nitinol spinal rods with titanium (Ti6Al4V) pedicle screws were tested in-vitro by conducting a series of potentiostatic measurements of the peak-to-peak values of fretting corrosion current under bending in a 10% solution of calf serum in PBS. The test included Nitinol rods locked in titanium pedicle screws of different designs. Performance of commercially available titanium (Ti6Al4V) and CoCr spinal rods was also investigated for a comparison. Corrosion damage observed after the in-vitro tests was studied using SEM and EDAX analysis and was compared with patterns on Nitinol rods retrieved 12months after initial surgery. Metal ions level was measured in the test media after in-vitro experiments and in the blood and tissues of the patients who had the rods explanted. The results of this study revealed that Nitinol spinal rods locked in Ti pedicle screws are susceptible to fretting corrosion demonstrating higher fretting corrosion current compared with commercially used Ti6Al4V and CoCr rods. On the surface of Nitinol rods after in-vitro tests and on those retrieved from the patients similar corrosion patterns were observed. Improved resistance to fretting corrosion was observed with Nitinol rods in the in-vitro tests where pedicle screws were used with a stiffer locking mechanism. Since the development of the localized corrosion damage might increase the risk of premature fatigue failure of the rods and result in leaching of Ni ions, it is concluded that Nitinol rods should not be used in conjunction with Ti pedicle screws without special protection especially where the design provides a high degree of mobility to the rods. Copyright © 2016 Elsevier B.V. All rights reserved.

Nuclear core and fuel assemblies

DOEpatents

Downs, Robert E.

1981-01-01

A fast flux nuclear core of a plurality of rodded, open-lattice assemblies having a rod pattern rotated relative to a rod support structure pattern. Elongated fuel rods are oriented on a triangular array and laterally supported by grid structures positioned along the length of the assembly. Initial inter-assembly contact is through strongbacks at the corners of the support pattern and peripheral fuel rods between adjacent assemblies are nested so as to maintain a triangular pitch across a clearance gap between the other portions of adjacent assemblies. The rod pattern is rotated relative to the strongback support pattern by an angle .alpha. equal to sin .sup.-1 (p/2c), where p is the intra-assembly rod pitch and c is the center-to-center spacing among adjacent assemblies.

Reactor control rod timing system. [LMFBR

DOEpatents

Wu, P.T.K.

1980-03-18

A fluid driven jet-edge whistle timing system is described for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

Reactor control rod timing system

DOEpatents

Wu, Peter T. K.

1982-01-01

A fluid driven jet-edge whistle timing system for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

Convergent synthesis of multiporphyrin light-harvesting rods

DOEpatents

Lindsey, Jonathan S.; Loewe, Robert S.

2003-08-05

The present invention provides a convergent method for the synthesis of light harvesting rods. The rods are oligomers of the formula A.sup.1 (A.sup.b+1).sub.b, wherein b is at least 1, A.sup.1 through A.sup.b+1 are covalently coupled rod segments, and each rod segment A.sup.1 through A.sup.1+b comprises a compound of the formula X.sup.1 (X.sup.m+1).sub.m wherein m is at least 1 and X.sup.1 through X.sup.m+1 are covalently coupled porphyrinic macrocycles. Light harvesting arrays and solar cells containing such light harvesting rods are also described, along with intermediates useful in such methods and rods produced by such methods.

Birefringence-balanced polarimetric optical fiber sensor for high-temperature measurements

NASA Technical Reports Server (NTRS)

Wang, Anbo; Wang, George Z.; Murphy, Kent A.; Claus, Richard O.

1992-01-01

A birefringence-balanced polarimetric multimode fiber temperature sensor is proposed and demonstrated. Two single-crystal sapphire rods are incorporated into the sensor head. They are connected end to end in such a way that the slow axis of the first rod is aligned with the fast axis of the second rod, referred to as the referencing rod. Since the lengths of the two rods are chosen to be almost the same, the original birefringence of the first rod is balanced by that of the second rod. A light-emitting diode serves as the light source. This sensor has been experimentally demonstrated for high-temperature measurements as high as 1500 C. A sensitivity of 5 C has been obtained.

REACTOR CONTROL ROD OPERATING SYSTEM

DOEpatents

Miller, G.

1961-12-12

A nuclear reactor control rod mechanism is designed which mechanically moves the control rods into and out of the core under normal conditions but rapidly forces the control rods into the core by catapultic action in the event of an emergency. (AEC)

Multi-function magnetic jack control drive mechanism

DOEpatents

Bollinger, L.R.; Crawford, D.C.

1983-10-06

A multi-function magnetic jack control drive mechanism for controlling a nuclear reactor is provided. The mechanism includes an elongate pressure housing in which a plurality of closely spaced drive rods are located. Each drive rod is connected to a rod which is insertable in the reactor core. An electromechanical stationary latch device is provided which is actuatable to hold each drive rod stationary with respect to the pressure housing. An electromechanical movable latch device is also provided for each one of the drive rods. Each movable latch device is provided with a base and is actuatable to hold a respective drive rod stationary with respect to the base. An electromechanical lift device is further provided for each base which is actuatable for moving a respective base longitudinally along the pressure housing. In this manner, one or more drive rods can be moved in the pressure housing by sequentially and repetitively operating the electromechanical devices. Preferably, each latch device includes a pair of opposed latches which grip teeth located on the respective drive rod. Two, three, or four drive rods can be located symmetrically about the longitudinal axis of the pressure housing.

Multi-function magnetic jack control drive mechanism

DOEpatents

Bollinger, Lawrence R.; Crawford, Donald C.

1986-01-01

A multi-function magnetic jack control drive mechanism for controlling a nuclear reactor is provided. The mechanism includes an elongate pressure housing in which a plurality of closely spaced drive rods are located. Each drive rod is connected to a rod which is insertable in the reactor core. An electromechanical stationary latch device is provided which is actuatable to hold each drive rod stationary with respect to the pressure housing. An electromechanical movable latch device is also provided for each one of the drive rods. Each movable latch device is provided with a base and is actuatable to hold a respective drive rod stationary with respect to the base. An electromechanical lift device is further provided for each base which is actuatable for moving a respective base longitudinally along the pressure housing. In this manner, one or more drive rods can be moved in the pressure housing by sequentially and repetitively operating the electromechanical devices. Preferably, each latch device includes a pair of opposed latches which grip teeth located on the respective drive rod. Two, three, or four drive rods can be located symmetrically about the longitudinal axis of the pressure housing.

Slip-spring model of entangled rod-coil block copolymers

NASA Astrophysics Data System (ADS)

Wang, Muzhou; Likhtman, Alexei E.; Olsen, Bradley D.

2015-03-01

Understanding the dynamics of rod-coil block copolymers is important for optimal design of functional nanostructured materials for organic electronics and biomaterials. Recently, we proposed a reptation theory of entangled rod-coil block copolymers, predicting the relaxation mechanisms of activated reptation and arm retraction that slow rod-coil dynamics relative to coil and rod homopolymers, respectively. In this work, we introduce a coarse-grained slip-spring model of rod-coil block copolymers to further explore these mechanisms. First, parameters of the coarse-grained model are tuned to match previous molecular dynamics simulation results for coils, rods, and block copolymers. For activated reptation, rod-coil copolymers are shown to disfavor configurations where the rod occupies curved portions of the entanglement tube of randomly varying curvature created by the coil ends. The effect of these barriers on diffusion is quantitatively captured by considering one-dimensional motion along an entanglement tube with a rough free energy potential. Finally, we analyze the crossover between the two mechanisms. The resulting dynamics from both mechanisms acting in combination is faster than from each one individually.

Superfund record of decision amendment (EPA Region 5): Allied Chemical and Ironton Coke, Ironton, OH, September 30, 1998

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This decision document, together with the Allied Chemical/Ironton Coke Record of Decision (ROD) dated December 28, 1990, the first Allied Chemical/Ironton Coke ROD Amendment dated July 31, 1995 (ROD Amendment No 1), and the second ROD Amendment dated September 4, 1997 (ROD Amendment No 2), presents the selected remedial action for the Allied Chemical/Ironton Coke site. The remedy selected in the 1990 ROD, 1995 ROD Amendment No. 1, and 1997 ROD Amendment No. 2 for the site is a final remedial action. Through ROD Amendment No. 3 the following components of the selected remedy are being modified: Replace in-situ bioremediationmore » of 457,000 cubic yards of soil in Lagoons 1--4 with hot spot excavation and wetland development; and Replace incineration of Lagoon 5 materials with recycling, treatment, and/or disposal of the K087 listed waste in an approved off-site hazardous waste facility and the use of the remaining material, excluding debris, as an alternative fuel.« less

Large Deformation of an Elastic Rod with Structural Anisotropy Subjected to Fluid Flow

NASA Astrophysics Data System (ADS)

Hassani, Masoud; Mureithi, Njuki; Gosselin, Frederick

2015-11-01

In the present work, we seek to understand the fundamental mechanisms of three-dimensional reconfiguration of plants by studying the large deformation of a flexible rod in fluid flow. Flexible rods made of Polyurethane foam and reinforced with Nylon fibers are tested in a wind tunnel. The rods have bending-torsion coupling which induces a torsional deformation during asymmetric bending. A mathematical model is also developed by coupling the Kirchhoff rod theory with a semi-empirical drag formulation. Different alignments of the material frame with respect to the flow direction and a range of structural properties are considered to study their effect on the deformation of the flexible rod and its drag scaling. Results show that twisting causes the flexible rods to reorient and bend with the minimum bending rigidity. It is also found that the drag scaling of the rod in the large deformation regime is not affected by torsion. Finally, using a proper set of dimensionless numbers, the state of a bending and twisting rod is characterized as a beam undergoing a pure bending deformation.

Experimental measurement of coil-rod-coil block copolymer tracer diffusion through entangled coil homopolymers

PubMed Central

Wang, Muzhou; Timachova, Ksenia; Olsen, Bradley D.

2014-01-01

The diffusion of coil-rod-coil triblock copolymers in entangled coil homopolymers is experimentally measured and demonstrated to be significantly slower than rod or coil homopolymers of the same molecular weight. A model coil-rod-coil triblock was prepared by expressing rodlike alanine-rich α-helical polypeptides in E. coli and conjugating coillike poly(ethylene oxide) (PEO) to both ends to form coil-rod-coil triblock copolymers. Tracer diffusion through entangled PEO homopolymer melts was measured using forced Rayleigh scattering at various rod lengths, coil molecular weights, and coil homopolymer concentrations. For rod lengths, L, that are close to the entanglementh length, a, the ratio between triblock diffusivity and coil homopolymer diffusivity decreases monotonically and is only a function of L/a, in quantitative agreement with previous simulation results. For large rod lengths, diffusion follows an arm retraction scaling, which is also consistent with previous theoretical predictions. These experimental results support the key predictions of theory and simulation, suggesting that the mismatch in curvature between rod and coil entanglement tubes leads to the observed diffusional slowing. PMID:25484454

Preparation of novel layer-stack hexagonal CdO micro-rods by a pre-oxidation and subsequent evaporation process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Kun, E-mail: kpeng@hnu.edu.cn; Hunan Province Key Laboratory for Spray Deposition Technology and Application, Hunan University, Changsha 410082; Jiang, Pan

2014-12-15

Graphical abstract: Layer-stack hexagonal cadmium oxide (CdO) micro-rods were prepared. - Highlights: • Novel hexagonal layer-stack structure CdO micro-rods were synthesized by a thermal evaporation method. • The pre-oxidation, vapor pressure and substrate nature play a key role on the formation of CdO rods. • The formation mechanism of CdO micro-rods was explained. - Abstract: Novel layer-stack hexagonal cadmium oxide (CdO) micro-rods were prepared by pre-oxidizing Cd granules and subsequent thermal oxidation under normal atmospheric pressure. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed to characterize the phase structure and microstructure. The pre-oxidation process, vapor pressure and substratemore » nature were the key factors for the formation of CdO micro-rods. The diameter of micro-rod and surface rough increased with increasing of thermal evaporation temperature, the length of micro-rod increased with the increasing of evaporation time. The formation of hexagonal layer-stack structure was explained by a vapor–solid mechanism.« less

[Novel Device for Creating Multiple Artificial Chordae Loops in Mitral Valve Repair].

PubMed

Shimamura, Yoshiei; Maisawa, Kazuma

2017-08-01

A novel device to create multiple artificial chordae loops for mitral repair is developed. The device consists of a circular metal base with a removable central rod on one end, which can easily be attached or removed by screwing into a hole located on the base, and 51 fixed rods placed radially around the central rod at distances of 10~60 mm from the central rod. A needle with CV-4 e-polytetrafluoroethylene suture is passed through a pledget, and the suture is looped from the central rod around the fixed rod located at the desired loop length. The needle is then passed back through the pledget. The suture is tied over the pledget, bringing it in contact with the central rod. When multiple loops of various lengths are required, different fixed rods located at distances corresponding to the required loop lengths are used. Following creation of the necessary loops, the central rod is unscrewed, and the loops are released from the device. Construction of artificial chordae with this device is quick, reliable, reproducible, and increases the technical possibilities for mitral valve repair.

Fabrication of Nanosized Island-Like CdO Crystallites-Decorated TiO₂ Rod Nanocomposites via a Combinational Methodology and Their Low-Concentration NO₂ Gas-Sensing Behavior.

PubMed

Liang, Yuan-Chang; Xu, Nian-Cih; Wang, Chein-Chung; Wei, Da-Hua

2017-07-10

TiO₂-CdO composite rods were synthesized through a hydrothermal method and sputtering thin-film deposition. The hydrothermally derived TiO₂ rods exhibited a rectangular cross-sectional crystal feature with a smooth surface, and the as-synthesized CdO thin film exhibited a rounded granular surface feature. Structural analyses revealed that the CdO thin film sputtered onto the surfaces of the TiO₂ rods formed a discontinuous shell layer comprising many island-like CdO crystallites. The TiO₂-CdO composite rods were highly crystalline, and their surfaces were rugged. A comparison of the NO₂ gas-sensing properties of the CdO thin film, TiO₂ rods, and TiO₂-CdO composite rods revealed that the composite rods exhibited superior gas-sensing responses to NO₂ gas than did the CdO thin film and TiO 2 rods, which can be attributed to the microstructural differences and the formation of heterojunctions between the TiO₂ core and CdO crystallites.

Suppressing turbulence of self-propelling rods by strongly coupled passive particles.

PubMed

Su, Yen-Shuo; Wang, Hao-Chen; I, Lin

2015-03-01

The strong turbulence suppression, mainly for large-scale modes, of two-dimensional self-propelling rods, by increasing the long-range coupling strength Γ of low-concentration passive particles, is numerically demonstrated. It is found that large-scale collective rod motion in forms of swirls or jets is mainly contributed from well-aligned dense patches, which can push small poorly aligned rod patches and uncoupled passive particles. The more efficient momentum transfer and dissipation through increasing passive particle coupling leads to the formation of a more ordered and slowed down network of passive particles, which competes with coherent dense active rod clusters. The frustration of active rod alignment ordering and coherent motion by the passive particle network, which interrupt the inverse cascading of forming large-scale swirls, is the key for suppressing collective rod motion with scales beyond the interpassive distance, even in the liquid phase of passive particles. The loosely packed active rods are weakly affected by increasing passive particle coupling due to the weak rod-particle interaction. They mainly contribute to the small-scale modes and high-speed motion.

Rod Has High Tensile Strength And Low Thermal Expansion

NASA Technical Reports Server (NTRS)

Smith, D. E.; Everton, R. L.; Howe, E.; O'Malley, M.

1996-01-01

Thoriated tungsten extension rod fabricated to replace stainless-steel extension rod attached to linear variable-differential transformer in gap-measuring gauge. Threads formed on end of rod by machining with special fixtures and carefully chosen combination of speeds and feeds.

Solid-state-laser-rod holder

DOEpatents

Gettemy, D.J.; Barnes, N.P.; Griggs, J.E.

1981-08-11

The disclosure relates to a solid state laser rod holder comprising Invar, copper tubing, and epoxy joints. Materials and coefficients of expansion of the components of the holder combine with the rod to produce a joint which will give before the rod itself will. The rod may be lased at about 70 to 80/sup 0/K and returned from such a temperature to room temperature repeatedly without its or the holder's destruction.

Fastening of a High-Strength Composite rod with a Splitted and Wedged end in a Potted Anchor 1. Experimental Investigation

NASA Astrophysics Data System (ADS)

Arnautov, A. K.; Terrasi, G. P.; Kulakov, V. L.; Portnov, G. G.

2014-01-01

The effectiveness of fastening of high-strength unidirectional CFRP/epoxy rods in potted anchors was investigated experimentally. The rods had splitted ends, in which duralumin wedges were glued. The experiments, performed for three types of contact between the composite rods and the potted material, showed that the most effective were full adhesion and adhesion-friction contacts, when the maximum load-carrying capacity of CFRP rods under tension could be reached. The full friction contact was ineffective because of the shear failure of CFRP rods inside the anchorage zone.

SAFETY SYSTEM FOR CONTROL ROD

DOEpatents

Paget, J.A.

1963-05-14

A structure for monitoring the structural continuity of a control rod foi a neutron reactor is presented. A electric conductor readily breakable under mechanical stress is fastened along the length of the control rod at a plurality of positions and forms a closed circuit with remote electrical components responsive to an open circuit. A portion of the conductor between the control rod and said components is helically wound to allow free and normally unrestricted movement of the segment of conductor secured to the control rod relative to the remote components. Any break in the circuit is indicative of control rod breakage. (AEC)

Neural net controlled tag gas sampling system for nuclear reactors

DOEpatents

Gross, Kenneth C.; Laug, Matthew T.; Lambert, John D. B.; Herzog, James P.

1997-01-01

A method and system for providing a tag gas identifier to a nuclear fuel rod and analyze escaped tag gas to identify a particular failed nuclear fuel rod. The method and system include disposing a unique tag gas composition into a plenum of a nuclear fuel rod, monitoring gamma ray activity, analyzing gamma ray signals to assess whether a nuclear fuel rod has failed and is emitting tag gas, activating a tag gas sampling and analysis system upon sensing tag gas emission from a failed nuclear rod and evaluating the escaped tag gas to identify the particular failed nuclear fuel rod.

The biomechanical consequences of rod reduction on pedicle screws: should it be avoided?

PubMed

Paik, Haines; Kang, Daniel G; Lehman, Ronald A; Gaume, Rachel E; Ambati, Divya V; Dmitriev, Anton E

2013-11-01

Rod contouring is frequently required to allow for appropriate alignment of pedicle screw-rod constructs. When residual mismatch is still present, a rod persuasion device is often used to achieve further rod reduction. Despite its popularity and widespread use, the biomechanical consequences of this technique have not been evaluated. To evaluate the biomechanical fixation strength of pedicle screws after attempted reduction of a rod-pedicle screw mismatch using a rod persuasion device. Fifteen 3-level, human cadaveric thoracic specimens were prepared and scanned for bone mineral density. Osteoporotic (n=6) and normal (n=9) specimens were instrumented with 5.0-mm-diameter pedicle screws; for each pair of comparison level tested, the bilateral screws were equal in length, and the screw length was determined by the thoracic level and size of the vertebra (35 to 45 mm). Titanium 5.5-mm rods were contoured and secured to the pedicle screws at the proximal and distal levels. For the middle segment, the rod on the right side was intentionally contoured to create a 5-mm residual gap between the inner bushing of the pedicle screw and the rod. A rod persuasion device was then used to engage the setscrew. The left side served as a control with perfect screw/rod alignment. After 30 minutes, constructs were disassembled and vertebrae individually potted. The implants were pulled in-line with the screw axis with peak pullout strength (POS) measured in Newton (N). For the proximal and distal segments, pedicle screws on the right side were taken out and reinserted through the same trajectory to simulate screw depth adjustment as an alternative to rod reduction. Pedicle screws reduced to the rod generated a 48% lower mean POS (495±379 N) relative to the controls (954±237 N) (p<.05) and significantly decreased work energy to failure (p<.05). Nearly half (n=7) of the pedicle screws had failed during the reduction attempt with visible pullout of the screw. After reduction, decreased POS was observed in both normal (p<.05) and osteoporotic (p<.05) bone. Back out and reinsertion of the screw resulted in no significant difference in mean POS, stiffness, and work energy to failure (p>.05). In circumstances where a rod is not fully seated within the pedicle screw, the use of a rod persuasion device decreases the overall POS and work energy to failure of the screw or results in outright failure. Further rod contouring or correction of pedicle screw depth of insertion may be warranted to allow for appropriate alignment of the longitudinal rods. Published by Elsevier Inc.

Monte Carlo simulation of evaporation-driven self-assembly in suspensions of colloidal rods

NASA Astrophysics Data System (ADS)

Lebovka, Nikolai I.; Vygornitskii, Nikolai V.; Gigiberiya, Volodymyr A.; Tarasevich, Yuri Yu.

2016-12-01

The vertical drying of a colloidal film containing rodlike particles was studied by means of kinetic Monte Carlo (MC) simulation. The problem was approached using a two-dimensional square lattice, and the rods were represented as linear k -mers (i.e., particles occupying k adjacent sites). The initial state before drying was produced using a model of random sequential adsorption (RSA) with isotropic orientations of the k -mers (orientation of the k -mers along horizontal x and vertical y directions are equiprobable). In the RSA model, overlapping of the k -mers is forbidden. During the evaporation, an upper interface falls with a linear velocity of u in the vertical direction and the k -mers undergo translation Brownian motion. The MC simulations were run at different initial concentrations, pi, (pi∈[0 ,pj] , where pj is the jamming concentration), lengths of k -mers (k ∈[1 ,12 ] ), and solvent evaporation rates, u . For completely dried films, the spatial distributions of k -mers and their electrical conductivities in both x and y directions were examined. Significant evaporation-driven self-assembly and orientation stratification of the k -mers oriented along the x and y directions were observed. The extent of stratification increased with increasing value of k . The anisotropy of the electrical conductivity of the film can be finely regulated by changes in the values of pi, k , and u .

315mJ, 2-micrometers Double-Pulsed Coherent Differential Absorption Lidar Transmitter for Atmospheric CO2 Sensing

NASA Technical Reports Server (NTRS)

Yu, Jirong; Trieu, Bo; Bai, Yingxin; Koch, Grady; Chen, Songsheng; Petzar, Paul; Singh, Upendra N.; Kavaya, Michael J.; Beyon, Jeffrey

2010-01-01

The design of a double pulsed, injection seeded, 2-micrometer compact coherent Differential absorption Lidar (DIAL) transmitter for CO2 sensing is presented. This system is hardened for ground and airborne applications. The design architecture includes three continuous wave lasers which provide controlled on and off line seeding, injection seeded power oscillator and a single amplifier operating in double pass configuration. As the derivative a coherent Doppler wind lidar, this instrument has the added benefit of providing wind information. The active laser material used for this application is a Ho: Tm:YLF crystal operates at the eye-safe wavelength. The 3-meter long folded ring resonator produces energy of 130-mJ (90/40) with a temporal pulse length around 220 nanoseconds and 530 nanosecond pulses for on and off lines respectively. The separation between the two pulses is on the order of 200 microseconds. The line width is in the order of 2.5MHz and the beam quality has an M(sup 2) of 1.1 times diffraction limited beam. A final output energy for a pair of both on and off pulses as high as 315 mJ (190/125) at a repetition rate of 10 Hz is achieved. The operating temperature is set around 20 C for the pump diode lasers and 10 C for the rod. Since the laser design has to meet high-energy as well as high beam quality requirements, close attention is paid to the laser head design to avoid thermal distortion in the rod. A side-pumped configuration is used and heat is removed uniformly by passing coolant through a tube slightly larger than the rod to reduce thermal gradient. This paper also discusses the advantage of using a long upper laser level life time laser crystal for DIAL application. In addition issues related to injection seeding with two different frequencies to achieve a transform limited line width will be presented.