A biomechanical analysis of the self-retaining pedicle hook device in posterior spinal fixation

PubMed Central

van Laar, Wilbert; Meester, Rinse J.; Smit, Theo H.

2007-01-01

Regular hooks lack initial fixation to the spine during spinal deformity surgery. This runs the risk of posterior hook dislodgement during manipulation and correction of the spinal deformity, that may lead to loss of correction, hook migration, and post-operative junctional kyphosis. To prevent hook dislodgement during surgery, a self-retaining pedicle hook device (SPHD) is available that is made up of two counter-positioned hooks forming a monoblock posterior claw device. The initial segmental posterior fixation strength of a SPHD, however, is unknown. A biomechanical pull-out study of posterior segmental spinal fixation in a cadaver vertebral model was designed to investigate the axial pull-out strength for a SPHD, and compared to the pull-out strength of a pedicle screw. Ten porcine lumbar vertebral bodies were instrumented in pairs with two different instrumentation constructs after measuring the bone mineral density of each individual vertebra. The instrumentation constructs were extracted employing a material testing system using axial forces. The maximum pull-out forces were recorded at the time of the construct failure. Failure of the SPHD appeared in rotation and lateral displacement, without fracturing of the posterior structures. The average pull-out strength of the SPHD was 236 N versus 1,047 N in the pedicle screws (P < 0.001). The pull-out strength of the pedicle screws showed greater correlation with the BMC compared to the SPHD (P < 0.005). The SPHD showed to provide a significant inferior segmental fixation to the posterior spine in comparison to pedicle screw fixation. Despite the beneficial characteristics of the monoblock claw construct in a SPHD, that decreases the risk of posterior hook dislodgement during surgery compared to regular hooks, the SPHD does not improve the pull-out strength in such a way that it may provide a biomechanically solid alternative to pedicle screw fixation in the posterior spine. PMID:17203270

High Temperature Mechanical Testing of a Cylindrical Weave Carbon-Carbon Composite.

DTIC Science & Technology

1985-07-01

umentation. 11. Photograph of the Calcination Furnace 46 and Automatic Controller/"Recorder. 12. Shear-Lao Specimen for both Axial 47 and Radial Fiber...Pull-out.S 13. Photograph of Displacement Frame Used to 48 Load Both the Pull-out Specimens and Axial Rupture Specimens. 14. Graph i te Loadi ng B1...tested in creep at 1800 C the spec imen shoted no el onga t i on w i th an ao a: I stre=ss of 11.4 ksi for 20 min. This was not surp r is i rg si nce Lu an

Quantitative in-situ scanning electron microscope pull-out experiments and molecular dynamics simulations of carbon nanotubes embedded in palladium

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

Hartmann, S., E-mail: steffen.hartmann@etit.tu-chemnitz.de; Blaudeck, T.; Hermann, S.

2014-04-14

In this paper, we present our results of experimental and numerical pull-out tests on carbon nanotubes (CNTs) embedded in palladium. We prepared simple specimens by employing standard silicon wafers, physical vapor deposition of palladium and deposition of CNTs with a simple drop coating technique. An AFM cantilever with known stiffness connected to a nanomanipulation system was utilized inside a scanning electron microscope (SEM) as a force sensor to determine forces acting on a CNT during the pull-out process. SEM-images of the cantilever attached to a CNT have been evaluated for subsequent displacement steps with greyscale correlation to determine the cantilevermore » deflection. We compare the experimentally obtained pull-out forces with values of numerical investigations by means of molecular dynamics and give interpretations for deviations according to material impurities or defects and their influence on the pull-out data. We find a very good agreement of force data from simulation and experiment, which is 17 nN and in the range of 10–61 nN, respectively. Our findings contribute to the ongoing research of the mechanical characterization of CNT-metal interfaces. This is of significant interest for the design of future mechanical sensors utilizing the intrinsic piezoresistive effect of CNTs or other future devices incorporating CNT-metal interfaces.« less

Analysis of Carbon Nanotube Pull-out from a Polymer Matrix

NASA Technical Reports Server (NTRS)

Frankland, S. J. V.; Harik, V. M.; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

Molecular dynamics (MD) simulations of carbon nanotube (NT) pull-out from a polymer matrix are carried out. As the NT pull-out develops in the simulation, variations in the displacement and velocities of the NT are monitored. The existence of a carbon-ring-based period in NT sliding during pull-out is identified. Linear trends in the NT velocity-force relation are observed and used to estimate an effective viscosity coefficient for interfacial sliding at the NT/polymer interface. As a result, the entire process of NT pull-out is characterized by an interfacial friction model that is based on a critical pull-out force, and an analog of Newton's friction law used to describe the NT/polymer interfacial sliding.

Pull-out simulations of a capped carbon nanotube in carbon nanotube-reinforced nanocomposites

NASA Astrophysics Data System (ADS)

Li, Y.; Liu, S.; Hu, N.; Han, X.; Zhou, L.; Ning, H.; Wu, L.; Alamusi, Yamamoto, G.; Chang, C.; Hashida, T.; Atobe, S.; Fukunaga, H.

2013-04-01

Systematic atomic simulations based on molecular mechanics were conducted to investigate the pull-out behavior of a capped carbon nanotube (CNT) in CNT-reinforced nanocomposites. Two common cases were studied: the pull-out of a complete CNT from a polymer matrix in a CNT/polymer nanocomposite and the pull-out of the broken outer walls of a CNT from the intact inner walls (i.e., the sword-in-sheath mode) in a CNT/alumina nanocomposite. By analyzing the obtained relationship between the energy increment (i.e., the difference in the potential energy between two consecutive pull-out steps) and the pull-out displacement, a set of simple empirical formulas based on the nanotube diameter was developed to predict the corresponding pull-out force. The predictions from these formulas are quite consistent with the experimental results. Moreover, the much higher pull-out force for a capped CNT than that of the corresponding open-ended CNT implies a significant contribution from the CNT cap to the interfacial properties of the CNT-reinforced nanocomposites. This finding provides a valuable insight for designing nanocomposites with desirable mechanical properties.

Pull-out simulations of a capped carbon nanotube in carbon nanotube-reinforced nanocomposites

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

Li, Y.; Liu, S.; Hu, N.

2013-04-14

Systematic atomic simulations based on molecular mechanics were conducted to investigate the pull-out behavior of a capped carbon nanotube (CNT) in CNT-reinforced nanocomposites. Two common cases were studied: the pull-out of a complete CNT from a polymer matrix in a CNT/polymer nanocomposite and the pull-out of the broken outer walls of a CNT from the intact inner walls (i.e., the sword-in-sheath mode) in a CNT/alumina nanocomposite. By analyzing the obtained relationship between the energy increment (i.e., the difference in the potential energy between two consecutive pull-out steps) and the pull-out displacement, a set of simple empirical formulas based on themore » nanotube diameter was developed to predict the corresponding pull-out force. The predictions from these formulas are quite consistent with the experimental results. Moreover, the much higher pull-out force for a capped CNT than that of the corresponding open-ended CNT implies a significant contribution from the CNT cap to the interfacial properties of the CNT-reinforced nanocomposites. This finding provides a valuable insight for designing nanocomposites with desirable mechanical properties.« less

Additive manufactured push-fit implant fixation with screw-strength pull out.

PubMed

van Arkel, Richard J; Ghouse, Shaaz; Milner, Piers E; Jeffers, Jonathan R T

2017-10-11

Additive manufacturing offers exciting new possibilities for improving long-term metallic implant fixation in bone through enabling open porous structures for bony ingrowth. The aim of this research was to investigate how the technology could also improve initial fixation, a precursor to successful long-term fixation. A new barbed fixation mechanism, relying on flexible struts was proposed and manufactured as a push-fit peg. The technology was optimized using a synthetic bone model and compared with conventional press-fit peg controls tested over a range of interference fits. Optimum designs, achieving maximum pull-out force, were subsequently tested in a cadaveric femoral condyle model. The barbed fixation surface provided more than double the pull-out force for less than a third of the insertion force compared to the best performing conventional press-fit peg (p < 0.001). Indeed, it provided screw-strength pull out from a push-fit device (1,124 ± 146 N). This step change in implant fixation potential offers new capabilities for low profile, minimally invasive implant design, while providing new options to simplify surgery, allowing for one-piece push-fit components with high levels of initial stability. © 2017 The Authors. Journal of Orthopaedic Research Published by WileyPeriodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 9999:1-11, 2017. © 2017 The Authors. Journal of Orthopaedic Research Published by WileyPeriodicals, Inc. on behalf of the Orthopaedic Research Society.

Sapphire reinforced alumina matrix composites

NASA Technical Reports Server (NTRS)

Jaskowiak, Martha H.; Setlock, John A.

1994-01-01

Unidirectionally reinforced A1203 matrix composites have been fabricated by hot pressing. Approximately 30 volume % of either coated or uncoated sapphire fiber was used as reinforcement. Unstabilized ZrO2 was applied as the fiber coating. Composite mechanical behavior was analyzed both after fabrication and after additional heat treatment. The results of composite tensile tests were correlated with fiber-matrix interfacial shear strengths determined from fiber push-out tests. Substantially higher strength and greater fiber pull-out were observed for the coated fiber composites for all processing conditions studied. The coated fiber composites retained up to 95% and 87% of their as-fabricated strength when heat treated at 14000C for 8 or 24 hours, respectively. Electron microscopy analysis of the fracture surfaces revealed extensive fiber pull-out both before and after heat treatment.

Mechanical and histological analysis of bone-pedicle screw interface in vivo: titanium versus stainless steel.

PubMed

Sun, C; Huang, G; Christensen, F B; Dalstra, M; Overgaard, S; Bünger, C

1999-05-01

To investigate the differences in bone interface between titanium and stainless steel pedicle screws in the lumbar spine. Eighteen adult mini-pigs that underwent total laminectomy, posterolateral spinal fusion (L4-L5) were randomly selected to receive stainless steel (9) or titanium pedicle screw devices (9). In both groups, the devices were CCD (Sofamore Danek) type with the same size and shape. The postoperative observation time was 3 months. Screws from L4 were harvested along their long axis of pedicle for histomorphometric study. Bone-screw interface and bone volume from thread were examined using linear intercept techniques. Mechanical testing (torsional test and pull-out test) was performed on the screws from L5. The titanium screw group had a significantly higher maximum torque (P < 0.05) and angle related stiffness (P < 0.05) measured by torsional test. In the pull-out tests, no differences were found between the two groups in relation to the maximum load, stiffness and energy to failure. Direct bone contact with the screw in percentage was 29.4% for stainless steel and 43.8% for titanium (P < 0.05). No differences in the bone purchase between the vertebral body part and pedicle part were found. Pedicle screws made of titanium have a better bone-screw interface binding than screws made of stainless steel. Torsional tests are more informative for bone-screw interface study. Pull-out tests seem less valuable when comparing bone purchase of screws made from different materials.

Characterization and Effects of Fiber Pull-Outs in Hole Quality of Carbon Fiber Reinforced Plastics Composite.

PubMed

Alizadeh Ashrafi, Sina; Miller, Peter W; Wandro, Kevin M; Kim, Dave

2016-10-13

Hole quality plays a crucial role in the production of close-tolerance holes utilized in aircraft assembly. Through drilling experiments of carbon fiber-reinforced plastic composites (CFRP), this study investigates the impact of varying drilling feed and speed conditions on fiber pull-out geometries and resulting hole quality parameters. For this study, hole quality parameters include hole size variance, hole roundness, and surface roughness. Fiber pull-out geometries are quantified by using scanning electron microscope (SEM) images of the mechanically-sectioned CFRP-machined holes, to measure pull-out length and depth. Fiber pull-out geometries and the hole quality parameter results are dependent on the drilling feed and spindle speed condition, which determines the forces and undeformed chip thickness during the process. Fiber pull-out geometries influence surface roughness parameters from a surface profilometer, while their effect on other hole quality parameters obtained from a coordinate measuring machine is minimal.

Analysis of the stiffness and load-bearing capacity of glued laminated timber beams reinforced with strands

NASA Astrophysics Data System (ADS)

Sardiko, R.; Rocens, K.; Iejavs, J.; Jakovlevs, V.; Ziverts, K.

2017-10-01

In this paper a benefit of glulam pinewood beams reinforced strands is discussed. In the first phase, series of pull-out tests were performed on specimens made up of different types of glue (melamine-urea-formaldehyde, epoxy and others) to detect pull-out force and failure mode of a specimens. In the second phase, series of equal cross-section glulam beams with strand and rod reinforcement were theoretically analysed using transformed cross-section method. Additionally, series of experimental testing were made. Benefits of strand reinforcement use as glulam beams’ reinforcement were identified and examined the possibility of one glue type application in all operations of reinforced glulam beams manufacturing.

Correlation of pull-out strength of cement-augmented pedicle screws with CT-volumetric measurement of cement.

PubMed

Fölsch, Christian; Goost, Hans; Figiel, Jens; Paletta, Jürgen R J; Schultz, Wolfgang; Lakemeier, Stefan

2012-12-01

Cement augmentation of pedicle screws increases fixation strength in an osteoporotic spine. This study was designed to determine the cement distribution and the correlation between the pull-out strength of the augmented screw and the cement volume within polyurethane (PU) foam. Twenty-eight cannulated pedicle screws (6×45 mm) (Peter Brehm, Erlangen, Germany) with four holes at the distal end of the screw were augmented with the acrylic Stabilit ER Bone Cement Vertebral Augmentation System (DFine Inc., San Jose, CA, USA) and implanted into open-cell rigid PU foam (Pacific Research Laboratories, Vashon Island, WA, USA) with a density of 0.12 g/cm3, resembling severe osteoporosis. Volumetric measurement of the cement with consideration of the distribution around the screws was done with multislice computed tomography scan (Somatom Definition, Siemens, Erlangen, Germany). Pull-out strength was tested with a servohydraulic system (MTS System Corporation, Eden Prairie, MN, USA), and nonaugmented screws served as control. Pearson's correlation coefficient with significance level α=0.05 and one-way analysis of variance test were used. We found a high (r=0.88) and significant (p<0.01) correlation between the cement volume and the pull-out strength, which increased by more than 5-fold with a volume of 3 ml. The correlation appeared linear at least up to 4 ml cement volume and failure always occurred at the cement-bone interface. The cement distribution was symmetric and circular around the most proximal hole, with a distance of 14 mm from the tip, and nearly 90% of the cement was found 6 mm distal and cranial to it. The 95% confidence interval for the relative amount of cement was 37%-41% within 2 mm of the most proximal hole. Compared with the control, a cement volume between 2.0 and 3.0 ml increased the pull-out strength significantly and is relevant for clinical purposes, whereas a volume of 0.5 ml did not. A cement volume beyond 3.0 ml should further increase the pull-out strength because the correlation was linear at least up to 4.0 ml, but the possibility of in vivo cement leakage with increasing volume has to be considered. Pressure-controlled cement application might be a tool to avoid this complication. The cement almost completely penetrated the most proximal perforation.

Direct Lentiviral-Cyclooxygenase 2 Application to the Tendon-Bone Interface Promotes Osteointegration and Enhances Return of the Pull-Out Tensile Strength of the Tendon Graft in a Rat Model of Biceps Tenodesis

PubMed Central

Wergedal, Jon E.; Stiffel, Virginia; Lau, Kin-Hing William

2014-01-01

This study sought to determine if direct application of the lentiviral (LV)-cyclooxygenase 2 (COX2) vector to the tendon-bone interface would promote osteointegration of the tendon graft in a rat model of biceps tenodesis. The LV-COX2 gene transfer strategy was chosen for investigation because a similar COX2 gene transfer strategy promoted bony bridging of the fracture gap during bone repair, which involves similar histologic transitions that occur in osteointegration. Briefly, a 1.14-mm diameter tunnel was drilled in the mid-groove of the humerus of adult Fischer 344 rats. The LV-COX2 or βgal control vector was applied directly into the bone tunnel and onto the end of the tendon graft, which was then pulled into the bone tunnel. A poly-L-lactide pin was press-fitted into the tunnel as interference fixation. Animals were sacrificed at 3, 5, or 8 weeks for histology analysis of osteointegration. The LV-COX2 gene transfer strategy enhanced neo-chondrogenesis at the tendon-bone interface but with only marginal effect on de novo bone formation. The tendon-bone interface of the LV-COX2-treated tenodesis showed the well-defined tendon-to-fibrocartilage-to-bone histologic transitions that are indicative of osteointegration of the tendon graft. The LV-COX2 in vivo gene transfer strategy also significantly enhanced angiogenesis at the tendon-bone interface. To determine if the increased osteointegration was translated into an improved pull-out mechanical strength property, the pull-out tensile strength of the LV-COX2-treated tendon grafts was determined with a pull-out mechanical testing assay. The LV-COX2 strategy yielded a significant improvement in the return of the pull-out strength of the tendon graft after 8 weeks. In conclusion, the COX2-based in vivo gene transfer strategy enhanced angiogenesis, osteointegration and improved return of the pull-out strength of the tendon graft. Thus, this strategy has great potential to be developed into an effective therapy to promote tendon-to-bone healing after tenodesis or related surgeries. PMID:24848992

In vivo mechanical study of helical cardiac pacing electrode interacting with canine myocardium

NASA Astrophysics Data System (ADS)

Zhang, Xiangming; Ma, Nianke; Fan, Hualin; Niu, Guodong; Yang, Wei

2007-06-01

Cardiac pacing is a medical device to help human to overcome arrhythmia and to recover the regular beats of heart. A helical configuration of electrode tip is a new type of cardiac pacing lead distal tip. The helical electrode attaches itself to the desired site of heart by screwing its helical tip into the myocardium. In vivo experiments on anesthetized dogs were carried out to measure the acute interactions between helical electrode and myocardium during screw-in and pull-out processes. These data would be helpful for electrode tip design and electrode/myocardium adherence safety evaluation. They also provide reliability data for clinical site choice of human heart to implant and to fix the pacing lead. A special design of the helical tip using strain gauges is instrumented for the measurement of the screw-in and pull-out forces. We obtained the data of screw-in torques and pull-out forces for five different types of helical electrodes at nine designed sites on ten canine hearts. The results indicate that the screw-in torques increased steplike while the torque time curves presente saw-tooth fashion. The maximum torque has a range of 0.3 1.9 N mm. Obvious differences are observed for different types of helical tips and for different test sites. Large pull-out forces are frequently obtained at epicardium of left ventricle and right ventricle lateral wall, and the forces obtained at right ventricle apex and outflow tract of right ventricle are normally small. The differences in pull-out forces are dictated by the geometrical configuration of helix and regional structures of heart muscle.

Comparison of mechanical behavior between implant-simulated bone tissue and implant-jaw bone tissue interfaces based on Pull Out testing

NASA Astrophysics Data System (ADS)

Lopez, C.; Muñoz, J. C.; Pinillos, J. C.

2013-11-01

The main purpose of this research was to achieve a better understanding of the relationship within the mechanical properties of human cadaver jaw bone with kind D2 density regarding a substitute polymer to simulate bone tissue, proposed by the ASTM, to evaluate orthopedic implants. However, despite the existence of several densities of foams and his mechanical characterization has been classified into different degrees of tissue densities to simulate cancellous and cortical bone, the value of the densities are different contrasted with the densities of bone tissue, making difficult to establish direct relationship about mechanical behavior between the polymer and the bone material, and therefore no clear criteria known for choosing the polymeric foam which describes the mechanical behavior of tissue for a specific or particular study. To understand such behavior from bone tissue regarding the polymer samples, on this research was a dental implant inserted into the samples, and subjected to destructive Pull Out test according to ASTM F543The Pull Out strength was compared between implant-jawbone and implant-rigid polyurethane foam interfaces. Thus, the test pieces with mechanical behavior similar to bone tissue, enabling an approximation to choose degree appropriate of polymer to replace the bone tissue in future trials biomechanical.

Characterization and Effects of Fiber Pull-Outs in Hole Quality of Carbon Fiber Reinforced Plastics Composite

PubMed Central

Alizadeh Ashrafi, Sina; Miller, Peter W.; Wandro, Kevin M.; Kim, Dave

2016-01-01

Hole quality plays a crucial role in the production of close-tolerance holes utilized in aircraft assembly. Through drilling experiments of carbon fiber-reinforced plastic composites (CFRP), this study investigates the impact of varying drilling feed and speed conditions on fiber pull-out geometries and resulting hole quality parameters. For this study, hole quality parameters include hole size variance, hole roundness, and surface roughness. Fiber pull-out geometries are quantified by using scanning electron microscope (SEM) images of the mechanically-sectioned CFRP-machined holes, to measure pull-out length and depth. Fiber pull-out geometries and the hole quality parameter results are dependent on the drilling feed and spindle speed condition, which determines the forces and undeformed chip thickness during the process. Fiber pull-out geometries influence surface roughness parameters from a surface profilometer, while their effect on other hole quality parameters obtained from a coordinate measuring machine is minimal. PMID:28773950

Ultrasonic Evaluation of the Pull-Off Adhesion between Added Repair Layer and a Concrete Substrate

NASA Astrophysics Data System (ADS)

Czarnecki, Slawomir

2017-10-01

This paper concerns the evaluation of the pull-off adhesion between a concrete added repair layer with variable thickness and a concrete substrate, based on parameters assessed using ultrasonic pulse velocity (UPV) method. In construction practice, the experimental determination of pull-off adhesion f b, between added repair layer and a concrete substrate is necessary to assess the quality of repair. This is usually carried out with the use of pull-off method which results in local damage of the added concrete layer in all the testing areas. Bearing this in mind, it is important to describe the method without these disadvantages. The prediction of the pull-off adhesion of the two-layer concrete elements with variable thickness of each layer might be provided by means of UPV method with two-sided access to the investigated element. For this purpose, two-layered cylindrical specimens were obtained by drilling the borehole from a large size specially prepared concrete element. Those two-layer elements were made out of concrete substrate layer and Polymer Cement Concrete (PCC) mortar as an added repair layer. The values of pull-off adhesion f b of the elements were determined before obtaining the samples by using the semi-destructive pull-off method. The ultrasonic wave velocity was determined in samples with variable thickness of each layer and was then compared to theoretical ultrasonic wave velocity predicted for those specimens. The regression curve for the dependence of velocity and pull-off adhesion, determined by the pulloff method, was made. It has been proved that together with an increase of ratio of investigated ultrasonic wave velocity divided by theoretical ultrasonic wave velocity, the pull-off adhesion value f b between added repair layer with variable thickness and a substrate layer also increases.

Inclusion at Risk? Push- and Pull-Out Phenomena in Inclusive School Systems: The Italian and Norwegian Experiences

ERIC Educational Resources Information Center

Nes, Kari; Demo, Heidrun; Ianes, Dario

2018-01-01

The main objective of this article is to explore and compare research data on pull-out and push-out phenomena within inclusive school systems, discussing if and how they represent a risk for inclusion. The terms pull-out and push-out refer to situations in which some groups of students in regular schools learn in settings apart from their peers.…

Effects of accelerated artificial daylight aging on bending strength and bonding of glass fibers in fiber-embedded maxillofacial silicone prostheses.

PubMed

Hatamleh, Muhanad M; Watts, David C

2010-07-01

The purpose of this study was to test the effect of different periods of accelerated artificial daylight aging on bond strength of glass fiber bundles embedded into maxillofacial silicone elastomer and on bending strength of the glass fiber bundles. Forty specimens were fabricated by embedding resin-impregnated fiber bundles (1.5-mm diameter, 20-mm long) into maxillofacial silicone elastomer. Specimens were randomly allocated into four groups, and each group was subjected to different periods of accelerated daylight aging as follows (in hours); 0, 200, 400, and 600. The aging cycle included continuous exposure to quartz-filtered visible daylight (irradiance 760 W/m(2)) under an alternating weathering cycle (wet for 18 minutes, dry for 102 minutes). Pull-out tests were performed to evaluate bond strength between fiber bundles and silicone using a universal testing machine at 1 mm/min crosshead speed. Also a three-point bending test was performed to evaluate bending strength of the fiber bundles. One-way ANOVA and Bonferroni post hoc tests were carried out to detect statistical significance (p < 0.05). Mean (SD) values of maximum pull-out forces (in N) for groups 1 to 4 were: 13.63 (7.45), 19.67 (1.37), 13.58 (2.61), and 10.37 (2.52). Group 2 exhibited the highest pull-out force that was statistically significant when compared to the other groups. Maximum bending strengths of fiber bundles were in the range of 917.72 MPa to 1124.06 MPa. Bending strength significantly increased after 200 and 400 hours of aging only. After 200 hours of exposure to artificial daylight and moisture conditions, bond strength between glass fibers and heat-cured silicones is optimal, and the bending strength of the glass fiber bundles is enhanced.

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.

TWO-LAYER MODEL FOR PULL-OUT BEHAVIOR OF POST-INSTALLED ANCHOR

NASA Astrophysics Data System (ADS)

Saleem, Muhammad; Tsubaki, Tatsuya

A new two-layer anchor-infill assembly structure for the post-installed anchor is introduced with the analytical model to simulate its pull-out deformational response. The post-installed anchor is such that used in strengthening techniques for reinforced concrete structures. The properties of the infill material used for post-installed anchor are characterized by nonlinear interfaces. Because of the mechanical properties of the infill layer the existing pull-out model of deformed bars is not applicable in this case. Interfacial de-bonding is examined using energy criterion and strength criterion. The effect of the interface properties such as stiffness and strength on the pull-out behavior of a post-installed anchor is investigated. Using sensitivity analysis, the effect of these parameters on load-displacement curve, shear stress distribution, de-bonded length and damage to the surrounding concrete is clarified. Then, the optimum combination of these parameters is presented. It is confirmed that the elastic modulus of infill should be large to reduce the pull-out displacement and the increase of the shear strength of infill makes the pull-out load larger.

Damage Tolerance Assessment of Friction Pull Plug Welds

NASA Technical Reports Server (NTRS)

McGill, Preston; Burkholder, Jonathan

2012-01-01

Friction stir welding is a solid state welding process developed and patented by The Welding Institute in Cambridge, England. Friction stir welding has been implemented in the aerospace industry in the fabrication of longitudinal welds in pressurized cryogenic propellant tanks. As the industry looks to implement friction stir welding in circumferential welds in pressurized cryogenic propellant tanks, techniques to close out the termination hole associated with retracting the pin tool are being evaluated. Friction pull plug welding is under development as a one means of closing out the termination hole. A friction pull plug weld placed in a friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite, plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size in the test or service environments. Test data relating residual strength capability to flaw size in two aluminum alloy friction plug weld configurations is presented.

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

Yuuichi Tooya; Tadahiro Washiya; Kenji Koizumi

Japan Atomic Energy Agency (JAEA) has been leading feasibility study on commercialized fast reactor cycle systems in Japan. In this study, we have proposed a new disassembly technology by mechanical disassembly system that consists of a mechanical cutting step and a wrapper tube pulling step. In the mechanical disassembly system, high durability mechanical tool grinds the wrapper tube (Slit-cut (S/C) operation in circle direction), and then the wrapper tube is pulled out and removed from the fuel assembly. Then the fuel pins are cut (Crop-cut (C/C) operation at entrance nozzle side) and the entrance nozzle is removed. The fuel pinsmore » are transported to the shearing device in next process. The Fundamental tests were carried out with simulated FBR fuel pins and wrapper tube, and cutting performance and wrapper tube pulling performance has been confirmed by engineering scale. As results, we established an efficient disassembly procedure and the fundamental design of mechanical disassembly system. (authors)« less

Posterior root tear of the medial meniscus in multiple knee ligament injuries.

PubMed

Kim, Young Jae; Kim, Jin Goo; Chang, Seok Hwan; Shim, Jae Chan; Kim, Sang Bum; Lee, Mi Young

2010-10-01

The purposes of the present study were to examine the frequency and characteristics of root tears of the medial meniscus associated with ligament injuries of the knee and to evaluate the effectiveness of pull-out repair for restoring meniscus function. We retrospectively analyzed the 9 patients (10 knees) with posterior root tears of the medial meniscus and ligament injuries of the knee treated between August 2004 and February 2007. All the patients were male, with average age of 29.8 years, and the mean follow-up period was 29.7 months. The pull-out suture technique was used to repair the root tears. Clinical outcomes were evaluated using the Lysholm, IKDC, and Tegner scores, as well as the McMurray and Apley tests. The mean follow-up period was 41.1 months (range, 30 to 63 months). The incidence of root tears of the medial meniscus with ligament injuries was 2.74% (10 cases in 365 ligament surgeries). All clinical results showed significant improvement. At the final follow-up, McMurray test showed one positive and nine negative cases, and the Apley test revealed two positive and eight negative cases. There were no positive findings in anterior drawer test, posterior drawer test, valgus and varus stress test, and posterolateral instability test. Healing of the root tear was confirmed by arthroscopy in five patients and by MR in four patients. Root tears of the medial meniscus may occur in multiple knee ligament injuries. It is important not to miss them. Our results indicate that pull-out repair provides satisfactory results and evidence of healing. Copyright 2009 Elsevier B.V. All rights reserved.

Biomechanical Comparisons of Pull Out Strengths After Pedicle Screw Augmentation with Hydroxyapatite, Calcium Phosphate, or Polymethylmethacrylate in the Cadaveric Spine.

PubMed

Yi, Seong; Rim, Dae-Cheol; Park, Seoung Woo; Murovic, Judith A; Lim, Jesse; Park, Jon

2015-06-01

In vertebrae with low bone mineral densities pull out strength is often poor, thus various substances have been used to fill screw holes before screw placement for corrective spine surgery. We performed biomechanical cadaveric studies to compare nonaugmented pedicle screws versus hydroxyapatite, calcium phosphate, or polymethylmethacrylate augmented pedicle screws for screw tightening torques and pull out strengths in spine procedures requiring bone screw insertion. Seven human cadaveric T10-L1 spines with 28 vertebral bodies were examined by x-ray to exclude bony abnormalities. Dual-energy x-ray absorptiometry scans evaluated bone mineral densities. Twenty of 28 vertebrae underwent ipsilateral fluoroscopic placement of 6-mm holes augmented with hydroxyapatite, calcium phosphate, or polymethylmethacrylate, followed by transpedicular screw placements. Controls were pedicle screw placements in the contralateral hemivertebrae without augmentation. All groups were evaluated for axial pull out strength using a biomechanical loading frame. Mean pedicle screw axial pull out strength compared with controls increased by 12.5% in hydroxyapatite augmented hemivertebrae (P = 0.600) and by 14.9% in calcium phosphate augmented hemivertebrae (P = 0.234), but the increase was not significant for either method. Pull out strength of polymethylmethacrylate versus hydroxyapatite augmented pedicle screws was 60.8% higher (P = 0.028). Hydroxyapatite and calcium phosphate augmentation in osteoporotic vertebrae showed a trend toward increased pedicle screw pull out strength versus controls. Pedicle screw pull out force of polymethylmethacrylate in the insertion stage was higher than that of hydroxyapatite. However, hydroxyapatite is likely a better clinical alternative to polymethylmethacrylate, as hydroxyapatite augmentation, unlike polymethylmethacrylate augmentation, stimulates bone growth and can be revised. Copyright © 2015 Elsevier Inc. All rights reserved.

Removing Background Noise with Phased Array Signal Processing

NASA Technical Reports Server (NTRS)

Podboy, Gary; Stephens, David

2015-01-01

Preliminary results are presented from a test conducted to determine how well microphone phased array processing software could pull an acoustic signal out of background noise. The array consisted of 24 microphones in an aerodynamic fairing designed to be mounted in-flow. The processing was conducted using Functional Beam forming software developed by Optinav combined with cross spectral matrix subtraction. The test was conducted in the free-jet of the Nozzle Acoustic Test Rig at NASA GRC. The background noise was produced by the interaction of the free-jet flow with the solid surfaces in the flow. The acoustic signals were produced by acoustic drivers. The results show that the phased array processing was able to pull the acoustic signal out of the background noise provided the signal was no more than 20 dB below the background noise level measured using a conventional single microphone equipped with an aerodynamic forebody.

An experimental study to investigate biomechanical aspects of the initial stability of press-fit implants.

PubMed

Berahmani, Sanaz; Janssen, Dennis; van Kessel, Sal; Wolfson, David; de Waal Malefijt, Maarten; Buma, Pieter; Verdonschot, Nico

2015-02-01

Initial fixation of press-fit implants depends on interference fit, surface morphology, and bone material properties. To understand the biomechanical effect of each factor and their interactions, the pull-out strength of seven types of CoCrMo tapered implants, with four different interference fits, three different surface morphologies (low, medium and high roughness), and at two time points (0 and 30 min) were tested in trabecular bone with varying density. The effect of interference fit on pull-out strength depended on the surface morphology and time. In contrast with our expectations, samples with a higher roughness had a lower pull-out strength. We found a similar magnitude of bone damage for the different surface morphologies, but the type of damage was different, with bone compaction versus bone abrasion for low and high frictional surfaces, respectively. This explains a reduced sensitivity of fixation strength to bone mineral density in the latter group. In addition, a reduction in fixation strength after a waiting period only occurred for the low frictional specimens. Our study demonstrates that it is essential to evaluate the interplay between different factors and emphasizes the importance of testing in natural bone in order to optimize the initial stability of press-fit implants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Study on Single-yarn Pullout Test of Ballistic Resistant Fabric under Different Preloads

NASA Astrophysics Data System (ADS)

Fang, Q. C.; Lei, Z. K.; Y Qin, F.; Li, W. K.; Bai, R. X.

2017-12-01

During bullet penetrating fabric, the pull-out force of yarn in fabric is related to the impact resistance of fabric when the yarn is pulled out from the fabric. The complex uncrimping and friction slip behavior occur during the yarn pullout process, which is critical to learn the impact resistance of fabric. Based on digital image correlation technique, the deformation behavior of Kevlar 49 fabric subjected to preload during the single-yarn pullout process was studied in this paper. The pullout force and displacement curve shows a straight rise and an oscillated decrease. In the linear rise stage, the yarn uncrimping causes a static friction effect. The maximum of the pullout force is not linearly increased with the preload. In the oscillating descending stage, the local descent of the pullout force indicates that the yarn end is gradually withdrawn from the fabric, and the local rise indicates that the yarn end moves to the next weft/warp interaction until the yarn is completely pulled out. The shear deformation of fabric corresponds to the single-yarn pullout process.

Assessment of the RIVET fixation system for cranioplasty using the pull-out technique.

PubMed

Sakamoto, Yoshiaki; Minabe, Toshiharu; Kato, Tatsuya; Kishi, Kazuo

2015-03-01

Cranioplasty using custom-made hydroxyapatite (HAP) ceramic implants is a common procedure to repair skull defects. However, commercially available titanium screws are only minimally stabilized due to characteristic brittleness. We developed the RIVET technique which involves fixing a bioabsorbable plate atop a HAP block using bioabsorbable screws extending beyond both layers, and evaluated fixation strength using the pull-out test and microtomography. Three experimental conditions were compared: a non-RIVET group, RIVET group, and dry skull control group. Pull-out strength significantly differed across groups (non-RIVET group, 1.33 ± 1.21 kgf; RIVET group, 4.46 ± 0.84 kgf; and control group, 6.99 ± 1.14 kgf, P < 0.01). Microtomography of the dry skull control group revealed thread grooves fitted to the screws. The non-RIVET and RIVET groups presented fewer thread grooves than the control group, and the screws did not fit perfectly to the HAP block. However, fixation in the RIVET group was more stable, as the rivet was firmly lodged into the implant. In conclusion, by melting and creating the rivet, pull-out strength can be increased and rigid stabilization of HAP can be obtained. This technique uses commercially available absorbable plate and screws, and thus can be used widely in clinical applications involving HAP blocks with different porosities and thicknesses. Copyright © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

In vivo testing of porous Ti-25Nb alloy serving as a femoral stem prosthesis in a rabbit model

PubMed Central

Weng, Xiaojun; Yang, Hailin; Xu, Jian; Li, Xiaosheng; Liao, Qiande; Wang, Jing

2016-01-01

The aim of the present study was to observe the performance of Ti-25Nb alloys with various porosities as femoral stem prostheses in a rabbit model, thus providing basic experimental evidence for the development of porous prostheses. The porous Ti-25Nb alloy prostheses were designed according to the morphology of the medullary cavity. These prostheses were placed into the femoral medullary cavities in 36 New Zealand white rabbits. Postoperative X-ray films, scanning electron microscopy (SEM) of the implant interface, energy-dispersive spectroscopy (EDS) analysis of the implant surface, pulling-out test and general observations were conducted. The specimens showed good biocompatibility; there was no obvious bone absorption in porous Ti-25Nb specimens with different porosities at different time points observed using X-ray films. Under SEM examination, calcium deposits were observed inside the pores and in the interface between bone and prostheses. The EDS analysis demonstrated that calcium deposits were present on the surface of the prostheses at the eight-week point postoperatively. The pulling-out test showed good bonding strength between bone and implant; after pulling out, the surface and inside the pores of the prostheses all presented bone mass. Porous Ti-25Nb alloy implants presents good biocompatibility as well as providing a biological fixation between the bone and implant. A porosity of 70% is more advantageous to the newborn bone ingrowth, combined with achieving a more solid bone-implant interface. PMID:27602063

Analysis of Effect of Rolling Pull-Outs on Wing and Aileron Loads of a Fighter Airplane

NASA Technical Reports Server (NTRS)

Pearson, Henry A.; Aiken, William S.

1946-01-01

An analysis was made to determine the effect of rolling pull-out maneuvers on the wing and aileron loads of a typical fighter airplane, the P-47B. The results obtained indicate that higher loads are imposed upon wings and ailerons because of the rolling pull-out maneuver, than would be obtained by application of the loading requirements to which the airplane was designed. An increase of 102 lb or 15 percent of wing weight would be required if the wing were designed for rolling pull-out maneuver. It was also determined that the requirements by which the aileron was originally designed were inadequate.

Trichotillomania (Hair-Pulling Disorder)

MedlinePlus

Trichotillomania (hair-pulling disorder) Overview Trichotillomania (trik-o-til-o-MAY-nee-uh), also called hair-pulling disorder, is a mental disorder that involves recurrent, irresistible urges to pull out hair from your scalp, eyebrows or other areas of ...

Effect of various factors on pull out strength of pedicle screw in normal and osteoporotic cancellous bone models.

PubMed

Varghese, Vicky; Saravana Kumar, Gurunathan; Krishnan, Venkatesh

2017-02-01

Pedicle screws are widely used for the treatment of spinal instability by spine fusion. Screw loosening is a major problem of spine fusion, contributing to delayed patient recovery. The present study aimed to understand the factor and interaction effects of density, insertion depth and insertion angle on pedicle screw pull out strength and insertion torque. A pull out study was carried out on rigid polyurethane foam blocks representing osteoporotic to normal bone densities according to the ASTM-1839 standard. It was found that density contributes most to pullout strength and insertion torque. The interaction effect is significant (p < 0.05) and contributes 8% to pull out strength. Axial pullout strength was 34% lower than angled pull out strength in the osteoporotic bone model. Insertion angle had no significant effect (p > 0.05) on insertion torque. Pullout strength and insertion torque had no significant correlation (p > 0.05) in the case of the extremely osteoporotic bone model. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

How far will a behaviourally flexible invasive bird go to innovate?

PubMed Central

Logan, Corina J.

2016-01-01

Behavioural flexibility is considered a key factor in the ability to adapt to changing environments. A traditional way of characterizing behavioural flexibility is to determine whether individuals invent solutions to novel problems, termed innovativeness. Great-tailed grackles are behaviourally flexible in that they can change their preferences when a task changes using existing behaviours; however, it is unknown how far they will go to invent solutions to novel problems. To begin to answer this question, I gave grackles two novel tests that a variety of other species can perform: stick tool use and string pulling. No grackle used a stick to access out-of-reach food, even after seeing a human demonstrate the solution. No grackle spontaneously pulled a vertically oriented string, but one did pull a horizontally oriented string twice. Additionally, a third novel test was previously conducted on these individuals and it was found that no grackle spontaneously dropped stones down a platform apparatus to release food, but six out of eight did become proficient after training. These results support the idea that behavioural flexibility is a multi-faceted trait because grackles are flexible, but not particularly innovative. This contradicts the idea that behavioural flexibility and innovativeness are interchangeable terms. PMID:27429781

Pull-out testing facility for geosynthetics.

DOT National Transportation Integrated Search

1992-11-01

The considerable increase in using geosynthetics in soil reinforcement made it necessary to develop methods of measuring the interaction properties and modeling load transfer in reinforced-soil structures. The large number of factors that influence t...

Capuchin monkeys, Cebus apella fail to understand a cooperative task

PubMed

Chalmeau; Visalberghi; Gallo

1997-11-01

We investigated whether capuchin monkeys cooperate to solve a task and to what extent they take into account the behaviour of another individual when cooperating. Two groups of capuchin monkeys (N=5 and 6) were tested in a task whose solution required simultaneous pulling of two handles which were too far from one another to be pulled by one monkey. Before carrying out the cooperation study, individual monkeys were trained to pull one handle (training phase 1) and to pull two handles simultaneously (training phase 2) for a food reward. Nine subjects were successful in training phase 1, and five in training phase 2. In the cooperation study seven subjects were successful, that is, pulled one handle while a companion pulled the other. Further analyses revealed that capuchins did not increase their pulling actions when a partner was close to or at the other handle, that is, when cooperation might occur. These data suggest that capuchin monkeys acted together at the task and got the reward without understanding the role of the partner and without taking its behaviour into consideration. Social tolerance, as well as their tendency to explore and their manual dexterity, were the major factors accounting for the capuchins' success.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour

Freezing of Rat Tibiae at -20°C Does Not Affect the Mechanical Properties of Intramedullary Bone/Implant-Interface: Brief Report

PubMed Central

Diefenbeck, Michael; Mückley, Thomas; Zankovych, Sergiy; Bossert, Jörg; Jandt, Klaus D; Schrader, Christian; Schmidt, Jürgen; Finger, Ulrich; Faucon, Mathilde

2011-01-01

Background: The effects of freezing-thawing cycles on intramedullary bone-implant interfaces have been studied in a rat model in mechanical pull-out tests. Implants: Twenty TiAl6V4 rods (Ø 0.8 mm, length 10 mm) implanted in rat tibiae Methods: 10 rats underwent bilateral tibial implantation of titanium rods. At eight weeks, the animals were sacrificed and tibiae harvested for biomechanical testing. Eight tibiae were frozen and stored at -20°C for 14 days, the remaining eight were evaluated immediately post-harvest. Pull-out tests were used to determine maximum force and interfacial shear strength. Results: There were no significant differences between fresh and those of the frozen-thawed group in maximum force or in interfacial shear strength. Conclusion: Frozen Storage of rat tibiae containing implants at -20° C has no effects on the biomechanical properties of Bone/ Implant interface. PMID:21760868

Mechanical stability of a novel screw design after repeated insertion: can the double-thread screw serve as a back up?

PubMed

Wiendieck, Kurt; Müller, Helge; Buchfelder, Michael; Sommer, Björn

2018-06-01

We investigated mechanical pull-out behavior and tightening torque of a novel dual-core pedicle "6T screw" (6T). The aim of this study was to test if these changes in screw geometry are increasing the strength of the pedicle screw fixation after repeated insertion. Three different types of pedicle screws were inserted in rigid foam blocks. Tightening torque and pull-out strength were measured during two repetitive insertions of a standard 6.5×45-mm conical screw. The third insertion into the pilot hole was performed using either standard 6.5×45-mm or 7.2×45-mm conical screws or the novel 6.5×45-mm (6T) screw. Additionally, we performed a surface analysis to investigate the bone/screw interface. The maximal tightening torque at the third insertion of the novel 6T screw was 194% higher compared to the standard 6.5×45-mm conical screw and 135% higher compared to the standard 7.2×45-mm conical screw. The pull-out strength of the 6T screw showed no significant changes, and surface analysis revealed a compression of the screw-foam interface due to the different internal diameters. The modified geometrical design of the 6T screw seems to have no statistically significant effect on the pull-out strength, although it achieved a higher tightening torque. This might be due to the different pitch angle cutting a new thread into the material and also to the enlarged inner diameter.

Drawbar Pull

DTIC Science & Technology

2017-01-26

Includes procedures for hard surface, soil , and water tests. Discusses vehicle preparation, instrumentation method of computing results, data reduction...and amphibious vehicles. 15. SUBJECT TERMS Bollard pull Soft- soil mobility Drawbar pull Vehicle, amphibious Drawbar horsepower Vehicle...4.3 Drawbar Pull in Soft Soil ................................................. 8 4.4 Amphibious Vehicle Tests (Drawbar Pull in Water and Bollard Pull

Cervical anterior transpedicular screw fixation (ATPS)—Part II. Accuracy of manual insertion and pull-out strength of ATPS

PubMed Central

Acosta, Frank; Tauber, Mark; Fox, Michael; Martin, Hudelmaier; Forstner, Rosmarie; Augat, Peter; Penzkofer, Rainer; Pirich, Christian; Kässmann, H.; Resch, Herbert; Hitzl, Wolfgang

2008-01-01

Reconstruction after multilevel decompression of the cervical spine, especially in the weakened osteoporotic, neoplastic or infectious spine often requires circumferential stabilization and fusion. To avoid the additional posterior surgery in these cases while increasing rigidity of anterior-only screw-plate constructs, the authors introduce the concept of anterior transpedicular screw (ATPS) fixation. We demonstrated its morphological feasibility as well as its indications in a previous study in Part I of our project. Consequently, the objectives of the current study were to assess the ex vivo accuracy of placing ATPS into the cervical vertebra as well as the biomechanical performance of ATPS in comparison to traditional vertebral body screws (VBS) in terms of pull-out strength (POS). Twenty-three ATPS were inserted alternately to two screws into the pedicles and vertebral bodies, respectively, of six cadaveric specimens from C3–T1. For insertion of ATPS, a manual fluoroscopically assisted technique was used. Pre- and post insertional CT-scans were used to assess accuracy of ATPS insertion in the axial and sagittal planes. A newly designed grading system and accuracy score were used to delineate accuracy of ATPS insertion. Following insertion of screws, 23 ATPS and 22 VBS were subjected to pull-out testing (POT). The bone mineral density (BMD) of each specimen was assessed prior to POT. Statistical analysis showed that the incidence of correctly placed screws and non-critical pedicles breaches in axial plane was 78.3%, and 95.7% in sagittal plane. Hence, according to our definition of “critical” pedicle breach that exposes neurovascular structures at risk, 21.7% (n = 5) of all ATPS inserted showed a critical pedicle breach in axial plane. Notably, no critical pedicle perforation occurred at the C6 to T1 levels. Pull-out testing of ATPS and VBS revealed that pull-out resistance of ATPS was 2.5-fold that of VBS. Mean POS of 23 ATPS with a mean BMD of 0.566 g/cm2 and a mean osseus screw purchase of 27.2 mm was 467.8 N. In comparison, POS of 22 VBS screws with a mean BMD of 0.533 g/cm2 and a mean osseus screw purchase of 16.0 mm was 181.6 N. The difference in ultimate pull-out strength between the ATPS and VBS group was significant (p < 0.000001). Also, accuracy of ATPS placement in axial plane was shown to be significantly correlated with POS. In contrast, there was no correlation between screw-length, BMD, or level of insertion and the POS of ATPS or VBS. The study demonstrated that the use of ATPS might be a new technique worthy of further investigation. The use of ATPS shows the potential to increase construct rigidity in terms of screw-plate pull-out resistance. It might diminish construct failures during anterior-only reconstructions of the highly unstable decompressed cervical spine. Electronic supplementary material The online version of this article (doi:10.1007/s00586-007-0573-x) contains supplementary material, which is available to authorized users. PMID:18224357

Construct Related Validity for the Baumgartner Modified Pull-Up Test

ERIC Educational Resources Information Center

Baumgartner, Ted A.; Gaunt, Sharon j.

2005-01-01

Traditionally the pull-up was used as a measure of arm and shoulder girdle strength and endurance. This measure did not discriminate among ability levels because many zero scores occur. Baumgartner (1978) developed a modified pull-up test that was easier than the traditional pull-up test. The Baumgartner Modified Pull-Up (BMPU) has been used as an…

Interface modification during oxidation of a glass-ceramic matrix/SiC fibre composite

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

Daniel, A.M.; Martin-Meizoso, A.; Plucknett, K.P.

Oxidation heat treatments between 375{degrees}C and 600{degrees}C for 100 hours in air, have been performed on the calcium aluminosilicate glass-ceramic matrix/SiC fibre reinforced composite CAS/Nicalon (manufactured by Corning, USA). Using a commercial nano-indentation system to perform fibre push-down tests, the fibre-matrix interfacial debond fracture surface energy (G{sub i}) and frictional shear stress ({tau}) have been determined. Modification of interface properties, compared to the as-fabricated material, was observed at heat treatment temperatures as low as 375{degrees}C, where a significant drop in G{sub i} and an increase in {tau} were recorded. With 450{degrees}C, 525{degrees}C and 600{degrees}C heat treatments, an increase in G{submore » i} but a dramatic increase in {tau} were recorded. Under four-point flexure testing, the as fabricated and the 375{degrees}C heat treated materials displayed tough, composite behaviour with extensive fibre pull out, but at {ge}450{degrees}C, brittle failure with minimal fibre pull out, was observed. This transition from tough mechanical response to one of brittleness is due to the large increase in {tau} reducing fibre pull out to a minimum and therefore reducing the total required work of fracture. The large increases in {tau} and G{sub i} have been attributed to the oxidative removal of the lubricating, carbon interface and the compressive residual stresses across the interface.« less

Interface modification during oxidation of a glass-ceramic matrix/SiC fibre composite

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

Daniel, A.M.; Martin-Meizoso, A.; Plucknett, K.P.

Oxidation heat treatments between 375{degrees}C and 600{degrees}C for 100 hours in air, have been performed on the calcium aluminosilicate glass-ceramic matrix/SiC fibre reinforced composite CAS/Nicalon (manufactured by Coming, USA). Using a commercial nano-indentation system to perform fibre push-down tests, the fibre-matrix interfacial debond fracture surface energy (G{sub i}) and frictional shear stress ({tau}) have been determined. Modification of interface properties, compared to the as fabricated material, was observed at heat treatment temperatures as low as 375{degrees}C, where a significant drop in G{sub i} and an increase in {tau} were recorded. With 450{degrees}C, 525{degrees}C and 600{degrees}C heat treatments, an increase inmore » G{sub i} but a dramatic increase in {tau} were recorded. Under four-point flexure testing, the as fabricated and the 375{degrees}C heat treated materials displayed tough, composite behaviour with extensive fibre pull out, but at {le}450{degrees}C, brittle failure with minimal fibre pull out, was observed. This transition from tough mechanical response to one of brittleness is due to the large increase in {tau} reducing fibre pull out to a minimum and therefore reducing the total required work of fracture. The large increases in {tau} and G{sub i} have been attributed to the oxidative removal of the lubricating, carbon interface and the compressive residual stresses across the interface.« less

The effect of a slack-pulling device in reducing operator physiological workload during log winching operations.

PubMed

Spinelli, Raffaele; Aalmo, Giovanna Ottaviani; Magagnotti, Natascia

2015-01-01

The authors conducted a comparative test to determine whether the introduction of a hydraulic slack puller allowed reducing the physiological workload of operators assigned to log winching tasks. The tests were conducted in northern Italy, on the mountains near Como. The study involved five volunteer subjects, considered representatives of the regional logging workforce. Physiological workload was determined by measuring the operators' heart rate upon completion of specific tasks. The slack puller improved the efficiency of downhill winching, since it allowed a single operator to pull out the cable on his own, without requiring the assistance of a colleague. However, introduction of the slack puller did not result in any reductions of operator physiological workload. The main stressor when working on a steep slope is moving up and down the slope: pulling a cable is only a secondary stressor. Any measures targeting secondary stressors are unlikely to produce dramatic reductions of operator workload.

Analysis of CFRP Joints by Means of T-Pull Mechanical Test and Ultrasonic Defects Detection.

PubMed

Casavola, Caterina; Palano, Fania; De Cillis, Francesco; Tati, Angelo; Terzi, Roberto; Luprano, Vincenza

2018-04-18

Defects detection within a composite component, with the aim of understanding and predicting its mechanical behavior, is of great importance in the aeronautical field because the irregularities of the composite material could compromise functionality. The aim of this paper is to detect defects by means of non-destructive testing (NDT) on T-pull samples made by carbon fiber reinforced polymers (CFRP) and to evaluate their effect on the mechanical response of the material. Samples, obtained from an industrial stringer having an inclined web and realized with a polymeric filler between cap and web, were subjected to ultrasonic monitoring and then to T-pull mechanical tests. All samples were tested with the same load mode and the same test configuration. An experimental set-up consisting of a semiautomatic C-scan ultrasonic mapping system with a phased array probe was designed and developed, optimizing control parameters and implementing image processing software. The present work is carried out on real composites parts that are characterized by having their intrinsic defectiveness, as opposed to the previous similar results in the literature mainly obtained on composite parts with artificially produced defects. In fact, although samples under study were realized free from defects, ultrasonic mapping found defectiveness inside the material. Moreover, the ultrasonic inspection could be useful in detecting both the location and size of defects. Experimental data were critically analyzed and qualitatively correlated with results of T-pull mechanical tests in order to better understand and explain mechanical behavior in terms of fracture mode.

Analysis of CFRP Joints by Means of T-Pull Mechanical Test and Ultrasonic Defects Detection

PubMed Central

Casavola, Caterina; Palano, Fania; De Cillis, Francesco; Tati, Angelo; Terzi, Roberto; Luprano, Vincenza

2018-01-01

Defects detection within a composite component, with the aim of understanding and predicting its mechanical behavior, is of great importance in the aeronautical field because the irregularities of the composite material could compromise functionality. The aim of this paper is to detect defects by means of non-destructive testing (NDT) on T-pull samples made by carbon fiber reinforced polymers (CFRP) and to evaluate their effect on the mechanical response of the material. Samples, obtained from an industrial stringer having an inclined web and realized with a polymeric filler between cap and web, were subjected to ultrasonic monitoring and then to T-pull mechanical tests. All samples were tested with the same load mode and the same test configuration. An experimental set-up consisting of a semiautomatic C-scan ultrasonic mapping system with a phased array probe was designed and developed, optimizing control parameters and implementing image processing software. The present work is carried out on real composites parts that are characterized by having their intrinsic defectiveness, as opposed to the previous similar results in the literature mainly obtained on composite parts with artificially produced defects. In fact, although samples under study were realized free from defects, ultrasonic mapping found defectiveness inside the material. Moreover, the ultrasonic inspection could be useful in detecting both the location and size of defects. Experimental data were critically analyzed and qualitatively correlated with results of T-pull mechanical tests in order to better understand and explain mechanical behavior in terms of fracture mode. PMID:29669992

An original architectured NiTi silicone rubber structure for biomedical applications.

PubMed

Rey, T; Le Cam, J-B; Chagnon, G; Favier, D; Rebouah, M; Razan, F; Robin, E; Didier, P; Heller, L; Faure, S; Janouchova, K

2014-12-01

This paper deals with composite structures for biomedical applications. For this purpose, an architectured tubular structure composed of Nickel Titanium (NiTi) Shape Memory Alloy (SMA) and silicone rubber was fabricated. One of the main interests of such structures is to ensure a good adhesion between its two constitutive materials. A previous study of the authors (Rey et al., 2014) has shown that the adhesion between NiTi and silicone rubber can be improved by an adhesion promoter or plasma treatment. However, adhesion promoters are often not biocompatible. Hence, plasma treatment is favored to be used in the present study. Three different gases were tested; air, argon and oxygen. The effects of these treatments on the maximum force required to pull-out a NiTi wire from the silicone rubber matrix were investigated by means of pull-out tests carried out with a self-developed device. Among the three gases, a higher maximum force was obtained for argon gas in the plasma treatment. A tube shaped architectured NiTi/silicone rubber structure was then produced using this treatment. The composite was tested by means of a bulge test. Results open a new way of investigations for architectured NiTi-silicone structures for biomechanical applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Influence of trabecular bone quality and implantation direction on press-fit mechanics.

PubMed

Damm, Niklas B; Morlock, Michael M; Bishop, Nicholas E

2017-02-01

Achieving primary stability of uncemented press-fit prostheses in patients with poor quality bone can involve axial implantation forces large enough to cause bone fracture. Radial implantation eliminates intraoperative impaction forces and could prevent this damage. Platens of two commercial implant surfaces ("Beaded" and "Flaked") were implanted onto trabecular bone specimens of varying quality in a press-fit simulator. Samples were implanted with varying interference, either axially (shear) or radially (normal). Push-in and pull-out forces were measured to assess stability. Microstructural changes in the bone were determined from μCT analysis. For force-defined implantation analysis, push-in and pull-out forces both increased proportionally with increasing radial force, independent of implantation direction, bone quality or implant surface. For position-defined implantation analysis, pull-out forces were generally found to increase with interference and to be greater for radial than axial implantation direction, and to be lower for poor quality bone. Bone density increased locally at the tested interface due to implantation, in particular for the Beaded surface under axial implantation. If a safe radial stress can be determined for cortical bone in a particular patient, the associated implantation force, and pull-out force which represents primary stability, can be directly derived, regardless of implantation direction, bone quality or implant surface. Radial implantation delivers primary stability that is no worse than that for axial implantation and may eliminate potentially damaging impaction forces. Development of implant designs based on this principal might improve implant fixation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:224-233, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

The influence of bone damage on press-fit mechanics.

PubMed

Bishop, Nicholas E; Höhn, Jan-Christian; Rothstock, Stephan; Damm, Niklas B; Morlock, Michael M

2014-04-11

Press-fitting is used to anchor uncemented implants in bone. It relies in part on friction resistance to relative motion at the implant-bone interface to allow bone ingrowth and long-term stability. Frictional shear capacity is related to the interference fit of the implant and the roughness of its surface. It was hypothesised here that a rough implant could generate trabecular bone damage during implantation, which would reduce its stability. A device was constructed to simulate implantation by displacement of angled platens with varying surface finishes (polished, beaded and flaked) onto the surface of an embedded trabecular bone cube, to different nominal interferences. Push-in (implantation) and Pull-out forces were measured and micro-CT scans were made before and after testing to assess permanent bone deformation. Depth of permanent trabecular bone deformation ('damage'), Pull-out force and Radial force all increased with implantation displacement and with implantation force, for all surface roughnesses. The proposed hypothesis was rejected, since primary stability did not decrease with trabecular bone damage. In fact, Pull-out force linearly increased with push-in force, independently of trabecular bone damage or implant surface. This similar behaviour for the different surfaces might be explained by the compaction of bone into the surfaces during push-in so that Pull-out resistance is governed by bone-on-bone, rather than implant surface-on-bone friction. The data suggest that maximum stability is achieved for the maximum implantation force possible (regardless of trabecular bone damage or surface roughness), but this must be limited to prevent periprosthetic cortical bone fracture, patient damage and component malpositioning. Copyright © 2014 Elsevier Ltd. All rights reserved.

Nanostructures and hydrophilicity influence osseointegration: a biomechanical study in the rabbit tibia.

PubMed

Wennerberg, Ann; Jimbo, Ryo; Stübinger, Stefan; Obrecht, Marcel; Dard, Michel; Berner, Simon

2014-09-01

Implant surface properties have long been identified as an important factor to promote osseointegration. The importance of nanostructures and hydrophilicity has recently been discussed. The aim of this study was to investigate how nanostructures and wettability influence osseointegration and to identify whether the wettability, the nanostructure or both in combination play the key role in improved osseointegration. Twenty-six adult rabbits each received two Ti grade 4 discs in each tibia. Four different types of surface modifications with different wettability and nanostructures were prepared: hydrophobic without nanostructures (SLA), with nanostructures (SLAnano); hydrophilic with two different nanostructure densities (low density: pmodSLA, high density: SLActive). All four groups were intended to have similar chemistry and microroughness. The surfaces were evaluated with contact angle measurements, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and interferometry. After 4 and 8 weeks healing time, pull-out tests were performed. SLA and SLAnano were hydrophobic, whereas SLActive and pmodSLA were super-hydrophilic. No nanostructures were present on the SLA surface, but the three other surface modifications clearly showed the presence of nanostructures, although more sparsely distributed on pmodSLA. The hydrophobic samples showed higher carbon contamination levels compared with the hydrophilic samples. After 4 weeks healing time, SLActive implants showed the highest pull-out values, with significantly higher pull-out force than SLA and SLAnano. After 8 weeks, the SLActive implants had the highest pull-out force, significantly higher than SLAnano and SLA. The strongest bone response was achieved with a combination of wettability and the presence of nanostructures (SLActive). © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Molecular dynamics simulations of the effect of waviness and agglomeration of CNTs on interface strength of thermoset nanocomposites.

PubMed

Alian, A R; Meguid, S A

2017-02-08

Most existing molecular dynamics simulations in nanoreinforced composites assume carbon nanotubes (CNTs) to be straight and uniformly dispersed within thermoplastics. In reality, however, CNTs are typically curved, agglomerated and aggregated as a result of van der Waal interactions and electrostatic forces. In this paper, we account for both curvature and agglomeration of CNTs in extensive molecular dynamic (MD) simulations. The purpose of these simulations is to evaluate the influence of waviness and agglomeration of these curved and agglomerated CNTs on the interfacial strength of thermoset nanocomposite and upon their load transfer capability. Two aspects of the work were accordingly examined. In the first, realistic carbon nanotubes (CNTs) of the same length but varied curvatures were embedded in thermoset polymer composites and simulations of pull-out tests were conducted to evaluate the corresponding interfacial shear strength (ISS). In the second, the effect of the agglomerate size upon the ISS was determined using bundles of CNTs of different diameters. The results of our MD simulations revealed the following. The pull-out force of the curved CNTs is significantly higher than its straight counterpart and increases further with the increase in the waviness of the CNTs. This is attributed to the added pull-out energy dissipated in straightening the CNTs during the pull-out process. It also reveals that agglomeration of CNTs leads to a reduction in the ISS and poor load transferability, and that this reduction is governed by the size of the agglomerate. The simulation results were also used to develop a generalized relation for the ISS that takes into consideration the effect of waviness and agglomeration of CNTs of CNT-polymer composites.

Stop/Start: Driving

Science.gov Websites

gasoline engine does not run when the vehicle is at rest. When pulling out, the electric starter/generator the gasoline engine when pulling out from a stop and generating electricity which is stored in the

Are single-well "push-pull" tests suitable tracer methods for aquifer characterization?

NASA Astrophysics Data System (ADS)

Hebig, Klaus; Zeilfelder, Sarah; Ito, Narimitsu; Machida, Isao; Scheytt, Traugott; Marui, Atsunao

2013-04-01

Recently, investigations were conducted for geological and hydrogeological characterisation of the sedimentary coastal basin of Horonobe (Hokkaido, Japan). Coastal areas are typical geological settings in Japan, which are less tectonically active than the mountain ranges. In Asia, and especially in Japan, these areas are often densely populated. Therefore, it is important to investigate the behaviour of solutes in such unconsolidated aquifers. In such settings sometimes only single boreholes or groundwater monitoring wells are available for aquifer testing for various reasons, e.g. depths of more than 100 m below ground level and slow groundwater velocities due to density driven flow. A standard tracer test with several involved groundwater monitoring wells is generally very difficult or even not possible at these depths. One of the most important questions in our project was how we can obtain information about chemical and hydraulic properties in such aquifers. Is it possible to characterize solute transport behaviour parameters with only one available groundwater monitoring well or borehole? A so-called "push-pull" test may be one suitable method for aquifer testing with only one available access point. In a push-pull test a known amount of several solutes including a conservative tracer is injected into the aquifer ("push") and afterwards extracted ("pull"). The measured breakthrough curve during the pumping back phase can then be analysed. This method has already been used previously with various aims, also in the recent project (e.g. Hebig et al. 2011, Zeilfelder et al. 2012). However, different test setups produced different tracer breakthrough curves. As no systematic evaluation of this aquifer tracer test method was done so far, nothing is known about its repeatability. Does the injection and extraction rate influence the shape of the breakthrough curve? Which role plays the often applied "chaser", which is used to push the test solution out from the borehole and gravel pack? How does density difference between the original groundwater and the test solution influence the tracer breakthrough curves? To solve these questions, seven push-pull tests were performed under controlled boundary conditions in the same well DD-2 (100 m depth). Only single parameters, as e.g. flow rate or salinization of the test solution, were varied during the experiments. By conducting these different test setups, conclusions could be drawn about the application of the push-pull method under different settings. References: Hebig, K.H., Ito, N., Scheytt, T.J. & Marui, A. (2011). Hydraulic and hydrochemical characterization of deep coastal sedimentary basins by single-well Push-Pull tests. GSA Annual Meeting, 9-12 October 2011, Minneapolis, USA. Zeilfelder, S., Ito, N., Marui, A., Hebig, K. & Scheytt, T. (2012). Push-Pull-Test und Tracer-Test in ei-nem tiefen Grundwasserleiter in Kameoka, Japan. Kurzfassung in: Liedl, R., Burghardt, D., Simon, E., Reimann, T. & Kaufmann-Knoke (Hg.). Grundwasserschutz und Grundwassernutzung. Tagung der Fachsektion Hydrogeologie in der DGG (FH-DGG). 16. - 20. Mai 2012, Dresden. Kurfassungen der Vorträge und Poster. Schriftenreihe der DGG, Heft 78, S. 192.

Intermediate Temperature Stress Rupture of a Woven Hi-Nicalon, BN-Interphase, SiC Matric Composite in Air

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Hurst, Janet; Brewer, David

1999-01-01

Woven Hi-Nicalon (TM) reinforced melt-infiltrated SiC matrix composites were tested under tensile stress-rupture conditions in air at intermediate temperatures. A comprehensive examination of the damage state and the fiber properties at failure was performed. Modal acoustic emission analysis was used to monitor damage during the experiment. Extensive microscopy of the composite fracture surfaces and the individual fiber fracture surfaces was used to determine the mechanisms leading to ultimate failure. The rupture properties of these composites were significantly worse than expected compared to the fiber properties under similar conditions. This was due to the oxidation of the BN interphase. Oxidation occurred through the matrix cracks that intersected the surface or edge of a tensile bar. These oxidation reactions resulted in minor degradation to fiber strength and strong bonding of the fibers to one another at regions of near fiber-to-fiber contact. It was found that two regimes for rupture exist for this material: a high stress regime where rupture occurs at a fast rate and a low stress regime where rupture occurs at a slower rate. For the high stress regime, the matrix damage state consisted of through thickness cracks. The average fracture strength of fibers that were pulled-out (the final fibers to break before ultimate failure) was controlled by the slow-crack growth rupture criterion in the literature for individual Hi-Nicalon (TM) fibers. For the low stress regime, the matrix damage state consisted of microcracks which grew during the rupture test. The average fracture strength of fibers that were pulled-out in this regime was the same as the average fracture strength of individual fibers pulled out in as-produced composites tested at room temperature.

Biomechanical evaluation of different suture techniques for arthroscopic transtibial pull-out repair of posterior medial meniscus root tears.

PubMed

Feucht, Matthias J; Grande, Eduardo; Brunhuber, Johannes; Burgkart, Rainer; Imhoff, Andreas B; Braun, Sepp

2013-12-01

A tear of the posterior medial meniscus root (PMMR) is increasingly recognized as a serious knee joint injury. Several suture techniques for arthroscopic transtibial pull-out repair have been described; however, only limited data about the biomechanical properties of these techniques are currently available. There are significant differences between the tested suture techniques, with more complex suture configurations providing superior biomechanical properties. Controlled laboratory study. A total of 40 porcine medial menisci were randomly assigned to 1 of 4 groups (10 specimens each) according to suture technique: two simple stitches (TSS), horizontal mattress suture (HMS), modified Mason-Allen suture (MMA), and two modified loop stitches (TLS). Meniscus-suture constructs were subjected to cyclic loading followed by load-to-failure testing in a servohydraulic material testing machine. During cyclic loading, the HMS and TLS groups showed a significantly higher displacement after 100, 500, and 1000 cycles compared with the TSS and MMA groups. After 1000 cycles, the highest displacement was found for the TLS group, with significant differences compared with all other groups. During load-to-failure testing, the highest maximum load and yield load were observed for the MMA group, with statistically significant differences compared with the TSS and TLS groups. With regard to stiffness, the TSS and MMA groups showed significantly higher values compared with the HMS and TLS groups. The MMA technique provided the best biomechanical properties with regard to cyclic loading and load-to-failure testing. The TSS technique seems to be a valuable alternative. Both the HMS and TLS techniques have the disadvantage of lower stiffness and higher displacement during cyclic loading. Using a MMA technique may improve healing rates and avoid progressive extrusion of the medial meniscus after transtibial pull-out repair of PMMR tears. The TSS technique may be used as an alternative that is easier to perform, but a more careful rehabilitation program is possibly necessary to avoid early failure.

Modeling of the fracture behavior of spot welds using advanced micro-mechanical damage models

NASA Astrophysics Data System (ADS)

Sommer, Silke

2010-06-01

This paper presents the modeling of deformation and fracture behavior of resistance spot welded joints in DP600 steel sheets. Spot welding is still the most commonly used joining technique in automotive engineering. In overloading situations like crash joints are often the weakest link in a structure. For those reasons, crash simulations need reliable and applicable tools to predict the load bearing capacity of spot welded components. Two series of component tests with different spot weld diameters have shown that the diameter of the weld nugget is the main influencing factor affecting fracture mode (interfacial or pull-out fracture), load bearing capacity and energy absorption. In order to find a correlation between nugget diameter, load bearing capacity and fracture mode, the spot welds are simulated with detailed finite element models containing base metal, heat affected zone and weld metal in lap-shear loading conditions. The change in fracture mode from interfacial to pull-out or peel-out fracture with growing nugget diameter under lap-shear loading was successfully modeled using the Gologanu-Leblond model in combination with the fracture criteria of Thomason and Embury. A small nugget diameter is identified to be the main cause for interfacial fracture. In good agreement with experimental observations, the calculated pull-out fracture initiates in the base metal at the boundary to the heat affected zone.

Mechanical verification of soft-tissue attachment on bioactive glasses and titanium implants.

PubMed

Zhao, Desheng; Moritz, Niko; Vedel, Erik; Hupa, Leena; Aro, Hannu T

2008-07-01

Soft-tissue attachment is a desired feature of many clinical biomaterials. The aim of the current study was to design a suitable experimental method for tensile testing of implant incorporation with soft-tissues. Conical implants were made of three compositions of bioactive glass (SiO(2)-P(2)O(5)-B(2)O(3)-Na(2)O-K(2)O-CaO-MgO) or titanium fiber mesh (porosity 84.7%). The implants were surgically inserted into the dorsal subcutaneous soft-tissue or back muscles in the rat. Soft-tissue attachment was evaluated by pull-out testing using a custom-made jig 8 weeks after implantation. Titanium fiber mesh implants had developed a relatively high pull-out force in subcutaneous tissue (12.33+/-5.29 N, mean+/-SD) and also measurable attachment with muscle tissue (2.46+/-1.33 N). The bioactive glass implants failed to show mechanically relevant soft-tissue bonding. The experimental set-up of mechanical testing seems to be feasible for verification studies of soft-tissue attachment. The inexpensive small animal model is beneficial for large-scale in vivo screening of new biomaterials.

Comparison of Transverse Intraosseous Loop Technique and Pull Out Suture for Reinsertion of the Flexor Digitorum Profundus tendon. A Retrospective Study.

PubMed

Rigó, István Zoltán; Røkkum, Magne

2013-12-01

We compared the results of two methods for reinsertion of flexor digitorum profundus tendons retrospectively. In 35 fingers of 29 patients pull-out suture and in 13 fingers of 11 patients transverse intraosseous loop technique was performed with a mean follow-up of 8 and 6 months, respectively. Eleven and nine fingers achieved "excellent" or "good" function according to Strickland and Glogovac at 8 weeks; 20 and ten at the last control in the pull-out and transverse intraosseous loop groups, respectively. The difference at 8 weeks was statistically significant in favour of the transverse intraosseous loop group. Ten patients underwent 12 complications in the pull-out group (four superficial infections; one rerupture, one PIP and one DIP joint contracture, one adhesion, two granulomas, one nail deformity and one carpal tunnel syndrome) and four of them were reoperated (one carpal tunnel release, one teno-arthrolysis and two resections of granuloma). There was no complication and no reoperation in the transverse intraosseous loop group, the difference being statistically significant for the former. In our study the transverse intraosseous loop technique seemed to be a safe alternative with possibly better functional results compared to the pull-out suture.

Altered tibiofemoral contact mechanics due to lateral meniscus posterior horn root avulsions and radial tears can be restored with in situ pull-out suture repairs.

PubMed

LaPrade, Christopher M; Jansson, Kyle S; Dornan, Grant; Smith, Sean D; Wijdicks, Coen A; LaPrade, Robert F

2014-03-19

An avulsion of the posterior root attachment of the lateral meniscus or a radial tear close to the root attachment can lead to degenerative knee arthritis. Although the biomechanical effects of comparable injuries involving the medial meniscus have been studied, we are aware of no such study involving the lateral meniscus. We hypothesized that in situ pull-out suture repair of lateral meniscus root avulsions and of complete radial tears 3 and 6 mm from the root attachment would increase the contact area and decrease mean and peak tibiofemoral contact pressures, at all knee flexion angles, relative to the corresponding avulsion or tear condition. Eight human cadaveric knees underwent biomechanical testing. Eight lateral meniscus conditions (intact, footprint tear, root avulsion, root avulsion repair, radial tears at 3 and 6 mm from the posterior root, and repairs of the 3 and 6-mm tears) were tested at five different flexion angles (0°, 30°, 45°, 60°, and 90°) under a compressive 1000-N load. Avulsion of the posterior root of the lateral meniscus or an adjacent radial tear resulted in significantly decreased contact area and increased mean and peak contact pressures in the lateral compartment, relative to the intact condition, in all cases except the root avulsion condition at 0° of flexion. In situ pull-out suture repair of the root avulsion or radial tear significantly reduced mean contact pressures, relative to the corresponding avulsion or tear condition, when the results for each condition were pooled across all flexion angles. Posterior horn root avulsions and radial tears adjacent to the root attachment of the lateral meniscus significantly increased contact pressures in the lateral compartment. In situ pull-out suture repairs of these tears significantly improved lateral compartment joint contact pressures. In situ repair may be an effective treatment to improve tibiofemoral contact profiles after an avulsion of the posterior root of the lateral meniscus or a complete radial tear adjacent to the root. In situ repairs should be further investigated clinically as an alternative to partial lateral meniscectomy.

Aerospace Power Journal. Volume 16, Number 1, Spring 2002

DTIC Science & Technology

2002-01-01

war fight­ ers (or “ pulled ” by requirements). Rather, they focused on “technology push”—systems that should be built merely because they could be...impact on our national security strategy. On 13 December 2001, President George W. Bush announced that the United States would pull out of the...to increase the arms race and pull out of previous treaties, as well as “shield of dreams” accusations), eco­ nomic reality (estimates run from

Finger-attachment device for the feedback of gripping and pulling force in a manipulating system for brain tumor resection.

PubMed

Chinbe, Hiroyuki; Yoneyama, Takeshi; Watanabe, Tetsuyou; Miyashita, Katsuyoshi; Nakada, Mitsutoshi

2018-01-01

Development and evaluation of an effective attachment device for a bilateral brain tumor resection robotic surgery system based on the sensory performance of the human index finger in order to precisely detect gripping- and pulling-force feedback. First, a basic test was conducted to investigate the performance of the human index finger in the gripping- and pulling-force feedback system. Based on the test result, a new finger-attachment device was designed and constructed. Then, discrimination tests were conducted to assess the pulling force and the feedback on the hardness of the gripped material. The results of the basic test show the application of pulling force on the side surface of the finger has an advantage to distinguish the pulling force when the gripping force is applied on the finger-touching surface. Based on this result, a finger-attachment device that applies a gripping force on the finger surface and pulling force on the side surface of the finger was developed. By conducting a discrimination test to assess the hardness of the gripped material, an operator can distinguish whether the gripped material is harder or softer than a normal brain tissue. This will help in confirming whether the gripped material is a tumor. By conducting a discrimination test to assess the pulling force, an operator can distinguish the pulling-force resistance when attempting to pull off the soft material. Pulling-force feedback may help avoid the breaking of blood pipes when they are trapped in the gripper or attached to the gripped tissue. The finger-attachment device that was developed for detecting gripping- and pulling-force feedback may play an important role in the development of future neurosurgery robotic systems for precise and safe resection of brain tumors.

Hair pull test: Evidence-based update and revision of guidelines.

PubMed

McDonald, Katherine A; Shelley, Amanda J; Colantonio, Sophia; Beecker, Jennifer

2017-03-01

The hair pull test lacks validation and has unclear pretest guidelines. We sought to quantify normal hair pull test values and elucidate the effect of pretest hair washing and brushing. The impact of hair texture and lifestyle was also examined. Participants (n = 181) completed a questionnaire recording demographics, medications, and hair health/history. A single hair pull test (scalp vertex) was performed. The mean number of hairs removed per pull was 0.44 (SD 0.75). There was no significant difference in the mean number of hairs removed regardless of when participants washed (P = .20) or brushed (P = .25) their hair. Hair pull test values were similar between Caucasian-, Asian-, and Afro-textured hair. There was no significant difference in hair pull values between participants taking medications affecting hair loss and participants not taking these medications (P = .33). Tight hairstyles did not influence hair pull test values. Participant hair washing and brushing could not be controlled during the study, but this information was documented and analyzed. Normal values for the hair pull test should be reduced to 2 hairs or fewer (97.2% of participants). The current 5-day restriction on pretest hair washing can be reduced and brushing be made permissible. Copyright © 2016 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

Professional Identity of a Reading Teacher: Responding to High-Stakes Testing Pressures

ERIC Educational Resources Information Center

Assaf, Lori Czop

2008-01-01

This case study explores the professional identity of one reading specialist, Marsha, who struggled with testing pressures at her urban elementary school in the U.S. It offers an in-depth look at how Marsha's instructional decisions and practices in a pull-out reading program aimed at helping English Language Learners (ELL) shifted when she was…

Evaluation of interaction properties of geosynthetics in cohesive soils : lab and field pull out tests : technical summary.

DOT National Transportation Integrated Search

2004-07-01

The objective of this research was to evaluate the pullout performance of geogrids and geotextiles in silty-clay soils. The results were correlated for various types of geogrid and geotextile reinforcements. This report presents an evaluation of the ...

Double transosseous pull out suture technique for transection of posterior horn of medial meniscus.

PubMed

Ahn, Jin Hwan; Wang, Joon Ho; Lim, Hong Chul; Bae, Ji Hoon; Park, Joon Soo; Yoo, Jae Chul; Shyam, Ashok Kumar

2009-03-01

Transection injury (complete radial tear, root tear) in the posterior horn of medial meniscus will lead to loss of hoop strain, extrusion of the meniscus and early degenerative changes. The posterior horn of medial meniscus is amenable to repair due to its good blood supply and repair is the procedure of choice for these injuries. In cases of transection of the medial meniscus posterior horn, the meniscus can be repaired by a pull out suture technique using trans-septal portal. The single transosseous pull out suturing technique is a point fixation technique with limited contact area having low and inhomogeneous contact pressure. This article describes a double transosseous pull out suture technique using trans-septal portal for the repair of transection of posterior horn of medial meniscus. Use of double transosseous technique provides more secure fixation, more homogeneous and wider contact pressure area between meniscus and the bone, improving the healing potential of the repair.

Attachment techniques for high temperature strain

NASA Astrophysics Data System (ADS)

Wnuk, Steve P., Jr.

1993-01-01

Attachment methods for making resistive strain measurements to 2500 F were studied. A survey of available strain gages and attachment techniques was made, and the results are compiled for metal and carbon composite test materials. A theoretical analysis of strain transfer into a bonded strain gage was made, and the important physical parameters of the strain transfer medium, the ceramic matrix, were identified. A pull tester to measure pull-out tests on commonly used strain gage cements indicated that all cements tested displayed adequate strength for good strain transfer. Rokide flame sprayed coatings produced significantly stronger bonds than ceramic cements. An in-depth study of the flame spray process produced simplified installation procedures which also resulted in greater reliability and durability. Application procedures incorporating improvements made during this program are appended to the report. Strain gages installed on carbon composites, Rene' 41, 316 stainless steel, and TZM using attachment techniques developed during this program were successfully tested to 2500 F. Photographs of installation techniques, test procedures, and graphs of the test data are included in this report.

Test and Analysis of Composite Hat Stringer Pull-off Test Specimens

NASA Technical Reports Server (NTRS)

Li, Jian; OBrien, T. Kevin; Rousseau, Carl Q.

1996-01-01

Hat stringer pull-off tests were performed to evaluate the delamination failure mechanisms in the flange region for a rod-reinforced hat stringer section. A special test fixture was used to pull the hat off the stringer while reacting the pull-off load through roller supports at both stringer flanges. Microscopic examinations of the failed specimens revealed that failure occurred at the ply termination in the flange area where the flange of the stiffener is built up by adding 45/-45 tape plies on the top surface. Test results indicated that the as-manufactured microstructure in the flange region has a strong influence on the delamination initiation and the associated pull-off loads. Finite element models were created for each specimen with a detailed mesh based on micrographs of the critical location. A fracture mechanics approach and a mixed mode delamination criterion were used to predict the onset of delamination and the pull-off load. By modeling the critical local details of each specimen from micrographs, the model was able to accurately predict the hat stringer pull-off loads and replicate the variability in the test results.

Modified Pull-out Suture in Posterior Root Tear of the Medial Meniscus: Using a Posteromedial Portal.

PubMed

Cho, Jin Ho

2012-06-01

In cases with root tear of the medial meniscus posterior horn, the meniscus usually can be repaired by a pull out suture technique. However, there is difficulty in manipulating a suture hook via the anteromedial portal and looking through the arthroscopic camera via anterolateral portal in the narrow medial joint space at the same time. This article describes a modified simple pull out suture technique for root tear of the medial meniscus posterior horn using a posteromedial portal that provides a safe and easy handling of the suture hook. Our indications of this technique used in patients with Outerbridge 1-2 arthritic change and minimal varus axis change. Benefits of this technique are simple, less invasive, and reduced operation time by simultaneous suture with a hook via posteromedial portal and pulling of a string with grasper. It may reduce the possibility of an additional chondral or meniscal injury.

Low temperature-pressure batch experiments and field push-pull tests: Assessing potential effects of an unintended CO2 release from CCUS projects on groundwater chemistry

NASA Astrophysics Data System (ADS)

Mickler, P. J.; Yang, C.; Lu, J.; Reedy, R. C.; Scanlon, B. R.

2012-12-01

Carbon Capture Utilization and Storage projects (CCUS), where CO2 is captured at point sources such as power stations and compressed into a supercritical liquid for underground storage, has been proposed to reduce atmospheric CO2 and mitigate global climate change. Problems may arise from CO2 releases along discreet pathways such as abandoned wells and faults, upwards and into near surface groundwater. Migrating CO2 may inversely impact fresh water resources by increasing mineral solubility and dissolution rates and mobilizing harmful trace elements including As and Pb. This study addresses the impacts on fresh water resources through a combination of laboratory batch experiments, where aquifer sediment are reacted in their corresponding groundwater in 100% CO2 environments, and field push-pull tests where groundwater is equilibrated with 100% CO2, reacted in-situ in the groundwater system, and pulled out for analyses. Batch experiments were performed on aquifer material from carbonate dominated, mixed carbonate/silicalstic, and siliclastic dominated systems. A mixed silicalstic/carbonate system was chosen for the field based push-pull test. Batch experiment results suggest carbonate dissolution increased the concentration of Ca, Mg, Sr, Ba, Mn, U and HCO3- in groundwater. In systems with significant carbonate content, dissolution continued until carbonate saturation was achieved at approximately 1000 hr. Silicate dissolution increased the conc. of Si, K Ni and Co, but at much lower rates than carbonate dissolution. The elements As, Mo, V, Zn, Se and Cd generally show similar behavior where concentrations initially increase but soon drop to levels at or below the background concentrations (~48 hours). A Push-Pull test on one aquifer system produced similar geochemical behavior but observed reaction rates are higher in batch experiments relative to push-pull tests. Release of CO2 from CCUS sites into overlying aquifer systems may adversely impact groundwater quality primarily through carbonate dissolution which releases Ca and elements that substitute for Ca in crystal lattices. Silicate weathering releases primarily Si and K at lower rates. Chemical changes with the addition of CO2 may initially mobilize As, Mo, V, Zn, Se and Cd but these elements become immobile in the lowered pH water and sorb onto aquifer minerals. A combined laboratory batch experiment and field push-pull test in fresh water aquifers overlying CCUS projects will best characterize the response of the aquifer to increased pCO2. The long experimental duration of the batch experiments may allow reactions to reach equilibrium however; reaction rates may be artificially high due to increased mineral surface areas. Field based push-pull tests offer a more realistic water rock ratio and test a much larger volume of aquifer material but the test must be shorter in duration because the high pCO2 water is subject to mixing with low pCO2 background water and migration away from the test well with groundwater flow. A comparison of the two methods best characterizes the potential effects on groundwater chemistry

Differential lead component pulling as a possible mechanism of inside-out abrasion and conductor cable externalization.

PubMed

Lau, Ernest W

2013-09-01

Conductor cable externalization with protrusion (CCE*) is highly prevalent among the Riata 8F and ST 7F defibrillation (DF) leads and infrequently present in the QuickSite and the QuickFlex coronary sinus (CS) leads (St. Jude Medical, Sylmar, CA, USA). A model for CCE* based on differential lead component pulling and conjugate extension with reciprocal compression-bending was developed. Extension of a proximal lead body segment by pectoral or cardiac movements causes reciprocal compression-bending of a distal lead body segment mediated by inextensible conductor cables running down a lead body fixed at various points by fibrous adhesions. The "sawing" action of these cables under tension causes inside-out abrasion of insulation leading to CCE*. DF leads from different manufacturers and the QuickFlex and QuickFlex μ CS leads were subjected to simulated differential pulling. Restitution from differential pulling followed three patterns: complete, partial without escalation, and incomplete with escalation. Only the last pattern (only shown by the Riata 8F and ST 7F leads) was associated with an increased risk to CCE*. For CS leads, deformation concentrated on the more flexible segment when the lead body did not have a uniform construction. The Durata, Riata ST Optim, QuickFlex μ, and Quartet leads should be relatively immune to CCE*. The Durata leads are extremely resistant to longitudinal deformation and probably cause mediastinal displacement rather than differential pulling in response to pectoral movements in vivo. Implantation techniques and lead designs can be used to minimize the risk of CCE*. A bench test for CCE* can be constructed. ©2013, The Author. Journal compilation ©2013 Wiley Periodicals, Inc.

Mechanism of oil-pulling therapy - in vitro study.

PubMed

Asokan, Sharath; Rathinasamy, T K; Inbamani, N; Menon, Thangam; Kumar, S Senthil; Emmadi, Pamela; Raghuraman, R

2011-01-01

Oil pulling has been used extensively as a traditional Indian folk remedy without scientific proof for many years for strengthening teeth, gums and jaws and to prevent decay, oral malodor, bleeding gums and dryness of throat and cracked lips. The aim of this study was to evaluate the antibacterial activity of sesame oil and lignans isolated from sesame oil on oral microorganisms and to check whether saponification or emulsification occurs during oil-pulling therapy. The in vitro study was carried out in three different phases: (1) Antibacterial activity of the lignans and sesame oil were tested by minimum inhibitory concentration assay by agar dilution method and agar well diffusion method, respectively. (2) Increase in free fatty acid level of oil and the quantity of sodium hydroxide (NaOH) used up in the titration are good indicators of saponification process. This was assessed using analytical tests for vegetable oils. (3) Swished oil was observed under light microscope to assess the status of the oil, presence of microorganisms, oral debris and foreign bodies. Sesamin and sesamolin isolated from sesame oil did not have any antibacterial effect against oral microorganisms like Streptococcus mutans, Streptococcus mitis and Streptococcus viridans. Emulsification of sesame oil occurs during oil-pulling therapy. Increased consumption of NaOH in titration is a definite indication of a possible saponification process. The myth that the effect of oil-pulling therapy on oral health was just a placebo effect has been broken and there are clear indications of possible saponification and emulsification process, which enhances its mechanical cleaning action.

Efficacy of a cosmetic phyto-caffeine shampoo in female androgenetic alopecia.

PubMed

Bussoletti, Carolina; Tolaini, Maria V; Celleno, Leonardo

2018-03-06

Androgenetic alopecia (AGA) is the most common type of hair loss in both males as well as females, occurring in up to 57% of women by the age of 80 years. Androgenetic alopecia is associated with a high psychological burden and often results in substantially reduced quality of life, poor body image and low self-esteem, particularly in women. Caffeine-based products have shown promise, both in vitro and in vivo, as potential treatments for AGA. This study was performed to determine the efficacy of a phyto-caffeine- containing shampoo used over a 6-month period in female subjects with AGA. This was a single-centre, double-blind parallel trial in which female subjects with AGA were randomized to either a phyto-caffeine-containing shampoo or a control shampoo. The primary endpoint was the change from baseline in the number of hairs pulled in a hair pull test at 6 months. Hair loss intensity, hair strength, subject satisfaction and tolerability were also assessed. Subjects using the phyto-caffeine-containing shampoo had significantly fewer hairs pulled in a hair pull test at 6 months, compared with subjects using the control shampoo (-3.1 vs -0.5 hairs; p<0.001). The majority of pre-specified secondary endpoints were also significantly improved for subjects using the phyto-caffeine- containing shampoo, compared with controls. Both products were very well tolerated. Compared with a control shampoo, a phyto-caffeine-containing shampoo was more efficacious, with respect to the number of hairs being pulled out at 6 months, hair loss intensity and hair strength in subjects with AGA.

Effect of coconut oil in plaque related gingivitis - A preliminary report.

PubMed

Peedikayil, Faizal C; Sreenivasan, Prathima; Narayanan, Arun

2015-01-01

Oil pulling or oil swishing therapy is a traditional procedure in which the practitioners rinse or swish oil in their mouth. It is supposed to cure oral and systemic diseases but the evidence is minimal. Oil pulling with sesame oil and sunflower oil was found to reduce plaque related gingivitis. Coconut oil is an easily available edible oil. It is unique because it contains predominantly medium chain fatty acids of which 45-50 percent is lauric acid. Lauric acid has proven anti inflammatory and antimicrobial effects. No studies have been done on the benefits of oil pulling using coconut oil to date. So a pilot study was planned to assess the effect of coconut oil pulling on plaque induced gingivitis. The aim of the study was to evaluate the effect of coconut oil pulling/oil swishing on plaque formation and plaque induced gingivitis. A prospective interventional study was carried out. 60 age matched adolescent boys and girls in the age-group of 16-18 years with plaque induced gingivitis were included in the study and oil pulling was included in their oral hygiene routine. The study period was 30 days. Plaque and gingival indices of the subjects were assessed at baseline days 1,7,15 and 30. The data was analyzed using paired t test. A statistically significant decrease in the plaque and gingival indices was noticed from day 7 and the scores continued to decrease during the period of study. Oil pulling using coconut oil could be an effective adjuvant procedure in decreasing plaque formation and plaque induced gingivitis.

Translations on Eastern Europe, Political, Sociological and Military Affairs, Number 1601

DTIC Science & Technology

1978-10-25

every house has lots of fishing gear, they all fish, throw out their lines and pull them in, and cry when there are no fish. Yet still we ail eat...every day. Everyone pulls out a kilogram a day at least. And what about poachers? There are enough of them here too. They can hardly wait for my...picked the lemons. Who else would do that but the local people, to pull such a prank." The mother would not hear of such a thing: "What do you

On the pull-out of fibers with fractal-tree structure and the interference of strength and fracture toughness of composites

NASA Astrophysics Data System (ADS)

Fe, Shaoyun; Zhou, Benlian; Lung, Chiwei

1992-06-01

An approximate theory of pull-out of fiber with fractal-tree structure from a matrix is developed with the aim of quantifying the effects of the fractal-tree structure of the fiber. In the experimental investigation of the pull-out of the synthetic fiber with fractal-tree structure, it was generally observed that the force and energy of fiber pullout increase with the branching angle. The application of this theory to experiment is successful. The strength and fracture toughness of composites reinforced by this kind of fiber are inferred to be greater than those of composites reinforced by plane fibers.

School Programs for At-Risk Children and Youth: A Review.

ERIC Educational Resources Information Center

McLaughlin, T. F.; Vacha, Edward F.

1992-01-01

A review of the literature regarding programs that assist the at-risk student found both pull-out and in-class models. Common elements of pull-out programs included such services as tutoring, skill-based structured instruction, and homework hot lines. In-class procedures included classwide peer tutoring, direct instruction, and cooperative…

Effect of laser heat treatment on Pull-out bond strength of fiber posts treated with different silanes.

PubMed

Shafiei, Fereshteh; Saadat, Maryam; Jowkar, Zahra

2018-05-01

This study evaluated the effect of three different silanes and post-silanization treatments on the retentive strength of fiber posts luted with an etch-and-rinse resin cement. One hundred intact maxillary central incisors were randomly divided into 10 groups after endodontic treatment and post space preparation (n=10). The fiber posts were etched using 24% hydrogen peroxide. Posts of the control group did not receive silane. In nine experimental groups, each of the three silanes used, Scotchbond Universal adhesive, Bis-Silane and Porcelain Primer, was subjected to three treatments: air-drying at 25°C, warm air-drying and CO2 laser heat treatment. After cementation of the treated posts using One-Step Plus/Duo-Link cement, the specimens were stored for one weak and then subjected to pull-out bond strength (PBS) testing. The data in Newton (N) were analyzed using two-way ANOVA and Tukey tests (α=0.05). PBS was significantly affected by silane type and post-silanization treatment ( p <0.001). The interaction of the two factors was not statistically significant ( p =0.15). The effect of Porcelain Primer on PBS was significantly higher than those of universal adhesive ( p <0.001) and Bis-Silane ( p =0.01), with similar results for the two latter. Warm air-drying and laser treatment significantly increased PBS ( p <0.001). The lowest and highest PBS was obtained in the control (no silane) group (190.9±31) and laser-treated/ Porcelain Primer group (377.1±50), respectively. Warm air-drying and CO2 laser heat treatment had a significantly beneficial effect on retentive strength of fiber posts. Porcelain Primer was significantly more effective than universal adhesive and Bis-Silane. Key words: Laser heat treatment, Pull-out bond strength, fiber post.

40 CFR 63.1384 - Performance test requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... performance test, the owner or operator must monitor and record the glass pull rate for each glass-melting furnace and, if different, the glass pull rate for each rotary spin manufacturing line and flame attenuation manufacturing line. Record the glass pull rate every 15 minutes during any performance test...

Using Bonding Enamel-Coated Steel Fixtures to Produce More Durable Brick/Masonry Structures

DTIC Science & Technology

2010-02-01

Initial tests with enameled metal straps cracked all the test cylinders and straps would not pull out BUILDING STRONG® New Strong Durable Ties...BUILDING STRONG® Using Bonding Enamel -Coated Steel Fixtures to Produce More Durable Brick/Masonry Structures Principal Investigator: Steven C...COVERED 00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE Using Bonding Enamel -Coated Steel Fixtures to Produce More Durable Brick/Masonry

Biomechanical evaluation of a transtibial pull-out meniscal root repair: challenging the bungee effect.

PubMed

Cerminara, Anthony J; LaPrade, Christopher M; Smith, Sean D; Ellman, Michael B; Wijdicks, Coen A; LaPrade, Robert F

2014-12-01

A common treatment for posterior meniscal root tears is transtibial pull-out repair, which has been biomechanically reported to restore tibiofemoral contact mechanics to those of the intact knee. Biomechanical data suggest that there is significant displacement of the repaired meniscal root with cyclic loading, which may be responsible for the poor healing and meniscal extrusion demonstrated in some clinical studies. The purpose of this study was to quantify the time-zero displacement of the posterior meniscal root in response to cyclic loading after transtibial pull-out repair and to quantify the individual contributions to displacement of the following: (1) suture elongation, (2) button-bone interface, and (3) meniscus-suture interface. The meniscus-suture interface was hypothesized to result in significantly more displacement than the button-bone interface or suture elongation. Descriptive laboratory study. Transtibial pull-out repair of the posterior medial meniscal root was performed in 6 porcine knees, and cyclic displacement was measured using a loading protocol representative of postoperative rehabilitation. Displacement from (1) suture elongation, (2) the button-bone interface, and (3) the meniscus-suture interface was determined by cyclically loading 6 specimens for each construct using the same loading protocol to determine the contribution of each component to the overall displacement of the repair construct. After 1000 cycles, the repair construct displaced by a mean of 3.28 mm (95% CI, 2.07-4.49). The meniscus-suture component (mean, 2.52 mm; 95% CI, 2.21-2.83) displaced significantly more than the button-bone component (mean, 0.90 mm; 95% CI, 0.64-1.15; P = .006) and suture elongation component (mean, 0.71 mm; 95% CI, 0.36-1.06; P = .006) after 1000 cycles. Displacement of the button-bone and suture elongation components was not significantly different after 1000 cycles (P = .720). There was substantial displacement of the posterior medial meniscal root repaired with the transtibial pull-out technique under a cyclic loading protocol simulating postoperative rehabilitation. The meniscus-suture interface contributed to significantly more displacement than the button-bone interface and suture elongation in the transtibial pull-out repair construct. The results provide a framework for optimizing the transtibial pull-out repair technique. Future studies should focus on improving suture fixation strength within the meniscus-suture interface. © 2014 The Author(s).

Analysis of Within-Test Variability of Non-Destructive Test Methods to Evaluate Compressive Strength of Normal Vibrated and Self-Compacting Concretes

NASA Astrophysics Data System (ADS)

Nepomuceno, Miguel C. S.; Lopes, Sérgio M. R.

2017-10-01

Non-destructive tests (NDT) have been used in the last decades for the assessment of in-situ quality and integrity of concrete elements. An important step in the application of NDT methods concerns to the interpretation and validation of the test results. In general, interpretation of NDT results should involve three distinct phases leading to the development of conclusions: processing of collected data, analysis of within-test variability and quantitative evaluation of property under investigation. The analysis of within-test variability can provide valuable information, since this can be compared with that of within-test variability associated with the NDT method in use, either to provide a measure of the quality control or to detect the presence of abnormal circumstances during the in-situ application. This paper reports the analysis of the experimental results of within-test variability of NDT obtained for normal vibrated concrete and self-compacting concrete. The NDT reported includes the surface hardness test, ultrasonic pulse velocity test, penetration resistance test, pull-off test, pull-out test and maturity test. The obtained results are discussed and conclusions are presented.

Effect of coconut oil in plaque related gingivitis — A preliminary report

PubMed Central

Peedikayil, Faizal C.; Sreenivasan, Prathima; Narayanan, Arun

2015-01-01

Background: Oil pulling or oil swishing therapy is a traditional procedure in which the practitioners rinse or swish oil in their mouth. It is supposed to cure oral and systemic diseases but the evidence is minimal. Oil pulling with sesame oil and sunflower oil was found to reduce plaque related gingivitis. Coconut oil is an easily available edible oil. It is unique because it contains predominantly medium chain fatty acids of which 45-50 percent is lauric acid. Lauric acid has proven anti inflammatory and antimicrobial effects. No studies have been done on the benefits of oil pulling using coconut oil to date. So a pilot study was planned to assess the effect of coconut oil pulling on plaque induced gingivitis. Materials and Methods: The aim of the study was to evaluate the effect of coconut oil pulling/oil swishing on plaque formation and plaque induced gingivitis. A prospective interventional study was carried out. 60 age matched adolescent boys and girls in the age-group of 16-18 years with plaque induced gingivitis were included in the study and oil pulling was included in their oral hygiene routine. The study period was 30 days. Plaque and gingival indices of the subjects were assessed at baseline days 1,7,15 and 30. The data was analyzed using paired t test. Results: A statistically significant decrease in the plaque and gingival indices was noticed from day 7 and the scores continued to decrease during the period of study. Conclusion: Oil pulling using coconut oil could be an effective adjuvant procedure in decreasing plaque formation and plaque induced gingivitis. PMID:25838632

Yo-Yo Pull Demonstration

ERIC Educational Resources Information Center

Layton, William

2013-01-01

A popular demonstration involves placing a yo-yo on a level table and gently pulling the string horizontally when it is wrapped to come out below the center of the yo-yo's axis. Students are then asked to predict which way the yo-yo will move. A similar demonstration is performed with a tricycle by pulling forward on a pedal with the pedal down in…

Peer Attitudes toward Students with Disabilities: A Comparison of the In-Class and Pull-Out Models of Service Delivery.

ERIC Educational Resources Information Center

Noland, Emily N.; And Others

1993-01-01

This study compared the differential effects of in-class and pull-out service delivery models on attitudes of students (n=194) in grades four through six toward students with disabilities. Results revealed that students from classrooms where services were being delivered through in-class service delivery models had more positive attitudes.…

Proximal half angle of the screw thread is a critical design variable affecting the pull-out strength of cancellous bone screws.

PubMed

Wang, Yingxu; Mori, Ryuji; Ozoe, Nobuaki; Nakai, Takahisa; Uchio, Yuji

2009-11-01

Screws with strong pull-out strength have been sought for the treatment of cancellous bone. We hypothesized that an obliquely angled screw thread has advantages over conventional vertical thread with a minimal proximal half angle. Metal and bone screws were made of stainless steel and porcine cortical bone. Their proximal half angle was set at 0 degrees , 30 degrees , or 60 degrees . The screws were inserted into porcine cancellous bone. At 0 degrees , the thread faced the recipient bone vertically. Pullout tests at a rate of 30 mm/min (n=40, each screw type) and microcomputed tomography (n=6) were conducted. The pull-out strength of the screws was maximal at 30 degrees ; 348.8 (SD, 44.1)N with metal and 326.6 (39.4)N with bone. It was intermediate at 0 degrees ; 301.9 (35.9)N with metal and 278.2 (30.6)N with bone. It was minimal at 60 degrees; 126.5 (39.0)N with metal and 174.8 (29.7)N with bone. Cancellous bone was damaged between the threads at 30 degrees , while intact cancellous bone was preserved between the threads at 0 degrees. A proximal half angle of around 30 degrees is appropriate because the pullout force is applied to the recipient bone evenly. Commercial cancellous screws can be improved by changing the thread shape to minimize the damage to recipient bone.

40 CFR 63.1384 - Performance test requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... parameter. (3) During each performance test, the owner or operator must monitor and record the glass pull rate for each glass-melting furnace and, if different, the glass pull rate for each rotary spin manufacturing line and flame attenuation manufacturing line. Record the glass pull rate every 15 minutes during...

40 CFR 63.1384 - Performance test requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... parameter. (3) During each performance test, the owner or operator must monitor and record the glass pull rate for each glass-melting furnace and, if different, the glass pull rate for each rotary spin manufacturing line and flame attenuation manufacturing line. Record the glass pull rate every 15 minutes during...

An Evaluation of Two English Language Learner (ELL) Instructional Models at School District ABC: Pull-In and Push-Out

ERIC Educational Resources Information Center

Lloyd, Sonya LaShawn

2014-01-01

Providing academic assistance to English Language Learners (ELLs) is varied and often ineffective. The purpose of this causal-comparative study was to determine if there was a relationship between 9th grade students' performance on the High School Graduation Exam (HSGE) in reading and language and the Push-in and Pull-out models of instruction.…

Micro/nano-mechanical test system employing tensile test holder with push-to-pull transformer

DOEpatents

Oh, Yunje; Cyrankowski, Edward; Shan, Zhiwei; Asif, Syed Amanula Syed

2013-05-07

A micromachined or microelectromechanical system (MEMS) based push-to-pull mechanical transformer for tensile testing of micro-to-nanometer scale material samples including a first structure and a second structure. The second structure is coupled to the first structure by at least one flexible element that enables the second structure to be moveable relative to the first structure, wherein the second structure is disposed relative to the first structure so as to form a pulling gap between the first and second structures such that when an external pushing force is applied to and pushes the second structure in a tensile extension direction a width of the pulling gap increases so as to apply a tensile force to a test sample mounted across the pulling gap between a first sample mounting area on the first structure and a second sample mounting area on the second structure.

Micro/nano-mechanical test system employing tensile test holder with push-to-pull transformer

DOEpatents

Oh, Yunje; Cyrankowski, Edward; Shan, Zhiwei; Syed Asif, Syed Amanula

2014-07-29

A micromachined or microelectromechanical system (MEMS) based push-to-pull mechanical transformer for tensile testing of micro-to-nanometer scale material samples including a first structure and a second structure. The second structure is coupled to the first structure by at least one flexible element that enables the second structure to be moveable relative to the first structure, wherein the second structure is disposed relative to the first structure so as to form a pulling gap between the first and second structures such that when an external pushing force is applied to and pushes the second structure in a tensile extension direction a width of the pulling gap increases so as to apply a tensile force to a test sample mounted across the pulling gap between a first sample mounting area on the first structure and a second sample mounting area on the second structure.

The Impact of Literacy Intervention on Academic Performance of Third Grade At-Risk Students

ERIC Educational Resources Information Center

Williams, Vernita

2015-01-01

Third grade at-risk students in Wilson County Schools, Wilson, NC continuously perform below the state average on the North Carolina Third Grade Reading End-of-Grade test. Leaders in the Wilson County Schools school district implemented a literacy pull-out intervention program for third grade at-risk students as a strategy to improve reading…

Research-Based Strategies to Ignite Student Learning: Insights from a Neurologist and Classroom Teacher

ERIC Educational Resources Information Center

Willis, Judy

2006-01-01

The author of this book combs through brain research and pulls out the information that is most valid and relevant to classroom teaching. It describes how to enhance students' memory and test-taking abilities and presents ways to captivate and hold students' attention and encourage their participation and progress. This is the first book ever…

Analysis of Full-Test tools and their limitations as applied to terminal junction blocks

NASA Technical Reports Server (NTRS)

Smith, J. L.

1983-01-01

Discovery of unlocked contacts in Deutsch Block terminal junctions in Solid Rocket Booster flight hardware prompted an investigation into pull test techniques to help insure against possible failures. Internal frictional forces between socket and pin and between wire and grommet were examined. Pull test force must be greater than internal friction yet less than the crimp strength of the pin or socket. For this reason, a 100 percent accurate test is impossible. Test tools were evaluated. Available tools are adequate for pull testing.

Experimental and Theoretical Investigations on Bond Strength of GFRP Rebars in Normal and High Strength Concrete

NASA Astrophysics Data System (ADS)

Eswanth, P.; Dhinakaran, G.

2017-07-01

Bond behavior between GFRP bars and concrete is the most important parameter for constructing corrosion free structures by implementing the material. Serviceability of reinforced concrete structures are controlled by bond behavior. GFRP materials behave differently from reinforcing steel in terms of bond. They are of non-homogeneous and anisotropic. Due to this outstanding behavior, there is a difference in transfer of loads between GFRP bars and concrete which made it as an idealized choice of a material. In the present work, the bond strength of GFRP bars in normal and high strength concrete was studied. In total, 12 specimens containing 12 mm, 16 mm diameter rebars which were embedded in 150 mm x 150 mm x 150 mm cubes were investigated. The specimens were subjected to direct tension pull out test in accordance with IS 2770 part 1. The comparison of bond properties of GFRP rebar in normal and high strength concrete showed that pull out load of non-metallic rebar fell well within the range.

Effect of placement angle on the stability of loaded titanium microscrews in beagle jaws.

PubMed

Xu, Zhenrui; Wu, Yeke; Zhao, Lixing; Zhou, Yuqiao; Wei, Xing; Tang, Na; Feng, Xiaoxia; Tang, Tian; Zhao, Zhihe

2013-07-01

To evaluate the effect of insertion angle on stability of loaded titanium microscrews in beagle jaws. Forty-eight microscrews were inserted at four different angles (30°, 50°, 70°, and 90°) into the intraradicular zones of the mandibular first molars and third premolars of 12 beagles and immediately loaded with a force of 2 N for 8 weeks. Microcomputed tomography (micro-CT) and biomechanical pull-out tests were used to assess osseointegration of the interface. All micro-CT parameters and maximum pull-out force (FMAX) of the microscrews were affected by insertion angles of microscrews. Higher micro-CT parameters and FMAX were seen for implants inserted at angles between 50° and 70° (P < .05). Excessive oblique and vertical insertion angles resulted in reduced stability (P < .05). An insertion angle of 50° to 70° is more favorable than excessive oblique or vertical angles to achieve stability of microscrews.

Ingrowing Hair

PubMed Central

Luo, Di-Qing; Liang, Yu-Hua; Li, Xi-Qing; Zhao, Yu-Kun; Wang, Fang; Sarkar, Rashmi

2016-01-01

Abstract Cutaneous pili migrans and creeping eruption caused by parasitic diseases may present as a moving linear lesion in skin. The former, caused by a hair shaft or fragment embedded in the superficial skin or middle dermis, is a rare condition characterized by creeping eruption with a black line observed at the advancing end. In exceptionally rare instance, the hair grows inside the skin and burrows in the uppermost dermis, such a condition has been called “ingrown hair.” We report a 30-year-old Chinese man, who was accustomed to pull or extrude the beard hairs, with 1-year history of slowly extending black linear eruption on his right chin. Cutaneous examination revealed a 4-cm long black linear lesion beneath the skin associated with edematous erythema around and folliculitis on both ends of the lesion. After treatment with topical mupirocin ointment, the erythema and folliculitis improved and 2 hairs of the beard with hair follicles were pulled out from the skin. Two weeks later, another similar black line about 1 cm in length in the skin presented on the prior lesional area, which was pulled out by a shallow incision of the skin and was also demonstrated as a beard hair with hair follicle. The patient was diagnosed as “ingrowing hair” with multiple recurrences. The lesions recovered after the beard hairs were pulled out. No recurrence occurred in a year of follow-up. We suggest that “ingrowing hair” is better than “ingrown hair” to describe such a condition. Pulling out the involved hair and correcting the bad practice are its optimal management strategies. PMID:27175694

Analytical solutions for efficient interpretation of single-well push-pull tracer tests

NASA Astrophysics Data System (ADS)

Huang, Junqi; Christ, John A.; Goltz, Mark N.

2010-08-01

Single-well push-pull tracer tests have been used to characterize the extent, fate, and transport of subsurface contamination. Analytical solutions provide one alternative for interpreting test results. In this work, an exact analytical solution to two-dimensional equations describing the governing processes acting on a dissolved compound during a modified push-pull test (advection, longitudinal and transverse dispersion, first-order decay, and rate-limited sorption/partitioning in steady, divergent, and convergent flow fields) is developed. The coupling of this solution with inverse modeling to estimate aquifer parameters provides an efficient methodology for subsurface characterization. Synthetic data for single-well push-pull tests are employed to demonstrate the utility of the solution for determining (1) estimates of aquifer longitudinal and transverse dispersivities, (2) sorption distribution coefficients and rate constants, and (3) non-aqueous phase liquid (NAPL) saturations. Employment of the solution to estimate NAPL saturations based on partitioning and non-partitioning tracers is designed to overcome limitations of previous efforts by including rate-limited mass transfer. This solution provides a new tool for use by practitioners when interpreting single-well push-pull test results.

Enhanced characterization of faults and fractures at EGS sites by CO2 injection coupled with active seismic monitoring, pressure-transient testing, and well logging

NASA Astrophysics Data System (ADS)

Oldenburg, C. M.; Daley, T. M.; Borgia, A.; Zhang, R.; Doughty, C.; Jung, Y.; Altundas, B.; Chugunov, N.; Ramakrishnan, T. S.

2016-12-01

Faults and fractures in geothermal systems are difficult to image and characterize because they are nearly indistinguishable from host rock using traditional seismic and well-logging tools. We are investigating the use of CO2 injection and production (push-pull) in faults and fractures for contrast enhancement for better characterization by active seismic, well logging, and push-pull pressure transient analysis. Our approach consists of numerical simulation and feasibility assessment using conceptual models of potential enhanced geothermal system (EGS) sites such as Brady's Hot Spring and others. Faults in the deep subsurface typically have associated damage and gouge zones that provide a larger volume for uptake of CO2 than the slip plane alone. CO2 injected for push-pull well testing has a preference for flowing in the fault and fractures because CO2 is non-wetting relative to water and the permeability of open fractures and fault gouge is much higher than matrix. We are carrying out numerical simulations of injection and withdrawal of CO2 using TOUGH2/ECO2N. Simulations show that CO2 flows into the slip plane and gouge and damage zones and is driven upward by buoyancy during the push cycle over day-long time scales. Recovery of CO2 during the pull cycle is limited because of buoyancy effects. We then use the CO2 saturation field simulated by TOUGH2 in our anisotropic finite difference code from SPICE-with modifications for fracture compliance-that we use to model elastic wave propagation. Results show time-lapse differences in seismic response using a surface source. Results suggest that CO2 can be best imaged using time-lapse differencing of the P-wave and P-to-S-wave scattering in a vertical seismic profile (VSP) configuration. Wireline well-logging tools that measure electrical conductivity show promise as another means to detect and image the CO2-filled fracture near the injection well and potential monitoring well(s), especially if a saline-water pre-flush is carried out to enhance conductivity contrast. Pressure-transient analysis is also carried out to further constrain fault zone characteristics. These multiple complementary characterization approaches are being used to develop working models of fault and fracture zone characteristics relevant to EGS energy recovery.

Seafloor Construction Experiment, SEACON II An Instrumented Tri-Moor for Evaluating Undersea Cable Structure Technology

DTIC Science & Technology

1976-12-01

ik’sigi. of undcruater cattle arrays wt’uld opertioal onsraitsbe the primari goali Arr. consitruction technolog% deseclopmcnt %%A% a %ccont!aro goal...weight of 12,500 pounds. struction mooring anchor was pulled out while load The anchor is composed of a 7-foot by 8-foot by and displacement were...out of the bottom. In contrast, anchor AI pulled out to 27,000 pounds for the construction moor anchor. at a load of 3,500 pounds although a 10,000

Effect of fiber surface conditioning on the acoustic emission behavior of steel fiber reinforced concrete

NASA Astrophysics Data System (ADS)

Aggelis, D. G.; Soulioti, D. V.; Gatselou, E.; Barkoula, N. M.; Paipetis, A.; Matikas, T. E.

2011-04-01

The role of coating in preserving the bonding between steel fibers and concrete is investigated in this paper. Straight types of fibers with and without chemical coating are used in steel fiber reinforced concrete mixes. The specimens are tested in bending with concurrent monitoring of their acoustic emission activity throughout the failure process using two broadband sensors. The different stages of fracture (before, during and after main crack formation) exhibit different acoustic fingerprints, depending on the mechanisms that are active during failure (concrete matrix micro-cracking, macro-cracking and fiber pull out). Additionally, it was seen that the acoustic emission behaviour exhibits distinct characteristics between coated and uncoated fiber specimens. Specifically, the frequency of the emitted waves is much lower for uncoated fiber specimens, especially after the main fracture incident, during the fiber pull out stage of failure. Additionally, the duration and the rise time of the acquired waveforms are much higher for uncoated specimens. These indices are used to distinguish between tensile and shear fracture in concrete and suggest that friction is much stronger for the uncoated fibers. On the other hand, specimens with coated fibers exhibit more tensile characteristics, more likely due to the fact that the bond between fibers and concrete matrix is stronger. The fibers therefore, are not simply pulled out but also detach a small volume of the brittle concrete matrix surrounding them. It seems that the effect of chemical coating can be assessed by acoustic emission parameters additionally to the macroscopic measurements of ultimate toughness.

The Biomechanical Properties of Pedicle Screw Fixation Combined With Trajectory Bone Cement Augmentation in Osteoporotic Vertebrae.

PubMed

Fan, Haitao T; Zhang, Renjie J; Shen, Cailiang L; Dong, Fulong L; Li, Yong; Song, Peiwen W; Gong, Chen; Wang, Yijin J

2016-03-01

The biomechanics of pedicle screw fixation combined with trajectory cement augmentation with various filling volumes were measured by pull-out, periodic antibending, and compression fatigue tests. To investigate the biomechanical properties of the pedicle screw fixation combined with trajectory bone cement (polymethylmethacrylate) augmentation in osteoporotic vertebrae and to explore the optimum filling volume of the bone cement. Pedicle screw fixation is considered to be the most effective posterior fixation method. The decrease of the bone mineral density apparently increases the fixation failure risk caused by screw loosening and displacement. Trajectory bone cement augmentation has been confirmed to be an effective method to increase the bone intensity and could markedly increase the stability of the fixation interface. Sixteen elderly cadaveric 1-5 lumbar vertebral specimens were diagnosed with osteoporosis. The left and right vertebral pedicles were alternatively randomized for treatment in all groups, with the contralateral pedicles as control. The study groups included: group A (pedicle screw fixation with full trajectory bone cement augmentation), group B (75% filling), group C (50% filling), and group D (25% filling). Finally, the bone cement leakage and dispersion were assessed and the mechanical testing was conducted. The bone cement was well dispersed around the pedicle screw. The augmented bone intensity, pull-out strength, periodic loading times, and compression fatigue performance were markedly higher than those of the control groups. With the increase in trajectory bone cement, the leakage was also increased (P<0.05). The pull-out strength of the pedicle screw was increased with an increase in bone mineral density and trajectory bone cement. It peaked at 75% filling, with the largest power consumption. The optimal filling volume of the bone cement was 75% of the trajectory volume (about 1.03 mL). The use of excessive bone cement did not increase the fixation intensity but increased the risk of leakage.

The Phenomenology of Hair Pulling Urges in Trichotillomania: A Comparative Approach

PubMed Central

Madjar, Shai; Sripada, Chandra S.

2016-01-01

Trichotillomania is a disorder characterized by recurrent urges to pull out one's hair, but the experiential characteristics of hair pulling urges are poorly understood. This study used a comparative approach to understand the subjective phenomenology of hair pulling: participants with trichotillomania symptoms were asked about their hair pulling urges as well as their urges to eat unhealthy foods. Participants who reported experiencing problematic unhealthy food urges were identified and asked to compare the phenomenological characteristics of their hair pulling and unhealthy food urges across a variety of dimensions. Results revealed significant differences for only some urge properties measured, and differences that existed were small to moderate in magnitude. Qualitative comparisons of the two urges revealed situational characteristics of hair pulling that could explain these small to moderate differences between the two urges. We conclude that hair pulling urges may be more comparable to ordinary urges such as unhealthy food urges than one might expect, but that hair pulling urges may nevertheless be rated as slightly more severe due to situational characteristics of these urges. This conception may improve clinician and lay understanding of the condition, assist with destigmatization efforts, and facilitate the development of treatment strategies. PMID:26925017

Biomechanical stability according to different configurations of screws and rods.

PubMed

Ha, Kee-Yong; Hwang, Sung-Chul; Whang, Tae-Hyuk

2013-05-01

Comparison of biomechanical strength according to 2 different configurations of screws and rods. To compare the biomechanical strength of different configurations of screws and rods composed of the same material and of the same size. Many complications related to instrumentation have been reported. The incidence of metallic failure would differ according to the materials and configurations of the assembly of the screws and rods used. However, to our knowledge, the biomechanical effects of implant assembly rods and screws with different configurations and different contours have not been reported. Biomechanical testing was conducted to compare top tightening (TT) screw-rod configuration with side tightening (ST) screw-rod configuration. All tests were conducted using a hydraulic all-purpose testing machine. All data were acquired at a rate of 10 Hz. Both screw systems used spinal rods of 6 mm diameter and were made of TiAl4V ELI material. Among 5 types of tests, 3 were conducted on the basis of American Society for Testing and Materials (ASTM) F 1798 to 97 and F1717-10. The other 2 tests were conducted for comparing the characteristics between TT and ST pedicle screws according to modified methods from ASTM F 1717-10 and ASTM F 1798-97. All results including axial gripping capacity and yield forces were obtained using the same methods on the basis of the mentioned ASTM standards. In the axial gripping capacity test, the mean axial gripping capacity of the TT screw-rod configuration was 3332 ± 118 N and that of ST was 2222 ± 147 N in straight rods (P = 0.019). In 15-degree contoured rods, TT was 2988 ± 199 N and ST was 2116 ± 423 N (P = 0.014). In 30-degree contoured rods, TT was 2227 ± 408 N and ST was 1814 ± 285 N (P = 0.009). In the pulling-out test, the pulling-out force of ST was 8695 ± 1616 N and that of TT was 6106 ± 195 N (P = 0.014). In the rod-pushing test, the failure force of ST was 4131 ± 205 N and that of TT was 5639 ± 105 N. In the compressive fatigue test, the maximum load was 145 N in ST and 119 N in TT. In the cycle fatigue test, the fatigue strength of ST was higher than that of TT. In the rod-pushing test, the failure force of ST was 4131 ± 205 N and that of TT was 5639 ± 105 N (P=0.046). Two different configurations of rod-screw systems found statistically significant differences with axial gripping, pulling out, and fatigue failures. ST constructs improved fixation stability over TT constructs. It was concluded that ST configuration may reduce complications related to implantation.

Gulf War Air Power Survey. Volume 1. Planning and Command and Control

DTIC Science & Technology

1993-01-01

should not simply pressure Saddam to pull out of Kuwait. Rather, it should continue until the Iraq army was destroyed. [DELET] m Schwa’rkopf. too, wanted...who pulled the OwAps sortie database into shape; retired Col. Donald A. Kellum, who uncovered the full story of close air support from records at Shaw...the maturing capability of airborne, decentralized command and control. Chapter 10 pulls all the chapters together around the distinction introduced

Low dose PTH improves metaphyseal bone healing more when muscles are paralyzed.

PubMed

Sandberg, Olof; Macias, Brandon R; Aspenberg, Per

2014-06-01

Stimulation of bone formation by PTH is related to mechanosensitivity. The response to PTH treatment in intact bone could therefore be blunted by unloading. We studied the effects of mechanical loading on the response to PTH treatment in bone healing. Most fractures occur in the metaphyses, therefor we used a model for metaphyseal bone injury. One hind leg of 20 male SD rats was unloaded via intramuscular botulinum toxin injections. Two weeks later, the proximal unloaded tibia had lost 78% of its trabecular contents. At this time-point, the rats received bilateral proximal tibiae screw implants. Ten of the 20 rats were given daily injections of 5 μg/kg PTH (1-34). After two weeks of healing, screw fixation was measured by pull-out, and microCT of the distal femur cancellous compartment was performed. Pull-out force provided an estimate for cancellous bone formation after trauma. PTH more than doubled the pull-out force in the unloaded limbs (from 14 to 30 N), but increased it by less than half in the loaded ones (from 30 to 44 N). In relative terms, PTH had a stronger effect on pull-out force in unloaded bone than in loaded bone (p=0.03). The results suggest that PTH treatment for stimulation of bone healing does not require simultaneous mechanical stimulation. Copyright © 2014 Elsevier Inc. All rights reserved.

Push-pull tests for estimating effective porosity: expanded analytical solution and in situ application

NASA Astrophysics Data System (ADS)

Paradis, Charles J.; McKay, Larry D.; Perfect, Edmund; Istok, Jonathan D.; Hazen, Terry C.

2018-03-01

The analytical solution describing the one-dimensional displacement of the center of mass of a tracer during an injection, drift, and extraction test (push-pull test) was expanded to account for displacement during the injection phase. The solution was expanded to improve the in situ estimation of effective porosity. The truncated equation assumed displacement during the injection phase was negligible, which may theoretically lead to an underestimation of the true value of effective porosity. To experimentally compare the expanded and truncated equations, single-well push-pull tests were conducted across six test wells located in a shallow, unconfined aquifer comprised of unconsolidated and heterogeneous silty and clayey fill materials. The push-pull tests were conducted by injection of bromide tracer, followed by a non-pumping period, and subsequent extraction of groundwater. The values of effective porosity from the expanded equation (0.6-5.0%) were substantially greater than from the truncated equation (0.1-1.3%). The expanded and truncated equations were compared to data from previous push-pull studies in the literature and demonstrated that displacement during the injection phase may or may not be negligible, depending on the aquifer properties and the push-pull test parameters. The results presented here also demonstrated the spatial variability of effective porosity within a relatively small study site can be substantial, and the error-propagated uncertainty of effective porosity can be mitigated to a reasonable level (< ± 0.5%). The tests presented here are also the first that the authors are aware of that estimate, in situ, the effective porosity of fine-grained fill material.

Air Operations in Israel’s War Against Hezbollah: Learning from Lebanon and Getting It Right in Gaza

DTIC Science & Technology

2011-01-01

alongside the 113 Steven Erlanger, “As Israel Begins to Pull Troops Out, Lebanon and the UN Prepare to Replace Them,” New York Times, August 16...engagement. Then, just before pulling abreast of the Ababil, he fired a Python 4 infrared missile using his helmet-mounted sight for high off-boresight...shock for two weeks after the Wehrmacht’s surprise attack on the Soviet Union in 1941, Nasrallah pulled himself back together fairly quickly. Shortly

A novel approach to determine primary stability of acetabular press-fit cups.

PubMed

Weißmann, Volker; Boss, Christian; Bader, Rainer; Hansmann, Harald

2018-04-01

Today hip cups are used in a large variety of design variants and in increasing numbers of units. Their development is steadily progressing. In addition to conventional manufacturing methods for hip cups, additive methods, in particular, play an increasingly important role as development progresses. The present paper describes a modified cup model developed based on a commercially available press-fit cup (Allofit 54/JJ). The press-fit cup was designed in two variants and manufactured using selective laser melting (SLM). Variant 1 (Ti) was modeled on the Allofit cup using an adapted process technology. Variant 2 (Ti-S) was provided with a porous load bearing structure on its surface. In addition to the typical (complete) geometry, both variants were also manufactured and tested in a reduced shape where only the press-fit area was formed. To assess the primary stability of the press-fit cups in the artificial bone cavity, pull-out and lever-out tests were carried out. Exact fit conditions and two-millimeter press-fit were investigated. The closed-cell PU foam used as an artificial bone cavity was mechanically characterized to exclude any influence on the results of the investigation. The pull-out forces of the Ti-variant (complete-526 N, reduced-468 N) and the Ti-S variant (complete-548 N, reduced-526 N) as well as the lever-out moments of the Ti-variant (complete-10 Nm, reduced-9.8 Nm) and the Ti-S variant (complete-9 Nm, reduced-7.9 N) show no significant differences in the results between complete and reduced cups. The results show that the use of reduced cups in a press-fit design is possible within the scope of development work. Copyright © 2018 Elsevier Ltd. All rights reserved.

Improving ISTEP Scores through Remediation: An Evaluation of the Language Arts Remediation at Chauncey Rose Middle School, Vigo County School Corporation.

ERIC Educational Resources Information Center

Emmert, Bryan E.

A study examined the effects of a remediation program initiated at Chauncey Rose Middle School, Terre Haute, Indiana, during the 1996-97 school year. After the ISTEP test was administered to the sixth-grade class, a pull-out program for remediation was started the following year using grant monies. Subjects were 14 sixth graders, selected because…

Structural basis for unique hierarchical cylindrites induced by ultrahigh shear gradient in single natural fiber reinforced poly(lactic acid) green composites.

PubMed

Xu, Huan; Xie, Lan; Jiang, Xin; Hakkarainen, Minna; Chen, Jing-Bin; Zhong, Gan-Ji; Li, Zhong-Ming

2014-05-12

A local shear flow field was feasibly generated by pulling the ramie fiber in single fiber reinforced poly(lactic acid) (PLA) composites. This was featured by an ultrahigh shear gradient with a maximum shear rate up to 1500 s(-1), a level comparable to that frequently occurring during the practical polymer processing. To distinguish shear-induced self-nucleation and ramie fiber-induced heterogeneous nucleation, the shear history was classified by pulling the fiber for 5 s (pulled sample) and pulling out the fiber during 10 s (pulled-out sample), while the static fiber-induced crystallization was carried out as the counterpart. As a result of the ultrahigh shear gradient, the combination of primary shear-induced nucleation in the central region and secondary nucleation in the outer layer assembled the unique hierarchical superstructures. By comparing the architectural configurations of interphases formed in the static, pulled, and pulled-out samples, it was shown that the hierarchical cylindrites underwent the process of self-nucleation driven by the applied shear flow, very different from the formation of fiber-induced transcrystallinity (TC) triggered by the heterogeneous nucleating sites at the static fiber surface. The twisting of transcrystallized lamellae may take place due to the spatial hindrance induced by the incredibly dense nuclei under the intense shearing flow, as observed in the synchrotron X-ray diffraction patterns. The influence of chain characteristics on the crystalline morphology was further explored by adding a small amount of poly(ethylene glycol) (PEG) to enhance the molecular mobility of PLA. It was of interest to find that the existence of PEG not only facilitated the growth rates of TC and cylindrites but also improved the preferential orientation of PLA chains and thus expanded the ordered regions. We unearthed lamellar units that were composed of rich fibrillar extended chain crystals (diameter of 50-80 nm). These results are of importance to shed light on tailoring crystalline morphology for natural fibers reinforced green composite materials. Of immense practical significance, too, is the crystalline evolution that has been tracked in the simple model penetrated with an ultrahigh shear gradient, which researchers have so far been unable to replicate during the practical melt processing, such as extrusion and injection molding.

Retention Strength of Conical Welding Caps for Fixed Implant-Supported Prostheses.

PubMed

Nardi, Diego; Degidi, Marco; Sighinolfi, Gianluca; Tebbel, Florian; Marchetti, Claudio

This study evaluated the retention strength of welding caps for Ankylos standard abutments using a pull-out test. Each sample consisted of an implant abutment and its welding cap. The tests were performed with a Zwick Roell testing machine with a 1-kN load cell. The retention strength of the welding caps increased with higher abutment diameters and higher head heights and was comparable or superior to the values reported in the literature for the temporary cements used in implant dentistry. Welding caps provide a reliable connection between an abutment and a fixed prosthesis without the use of cement.

Analytical solutions for efficient interpretation of single-well push-pull tracer tests

EPA Science Inventory

Single-well push-pull tracer tests have been used to characterize the extent, fate, and transport of subsurface contamination. Analytical solutions provide one alternative for interpreting test results. In this work, an exact analytical solution to two-dimensional equations descr...

Yo-yo Pull Demonstration

NASA Astrophysics Data System (ADS)

Layton, William

2013-03-01

A popular demonstration involves placing a yo-yo on a level table and gently pulling the string horizontally when it is wrapped to come out below the center of the yo-yo's axis. Students are then asked to predict which way the yo-yo will move. A similar demonstration is performed with a tricycle by pulling forward on a pedal with the pedal down in its lowest position.2,3 As well as pulling the yo-yo horizontally, often the string is lifted until the angle it makes with the table causes no motion. This occurs when the line extended from the string intersects the point of contact of the yo-yo with the table.4 This paper describes an apparatus that extends these demonstrations to the situation where the force pulling the yo-yo is still horizontal yet is below the level of the table.

INTERSESSION RELIABILITY OF UPPER EXTREMITY ISOKINETIC PUSH-PULL TESTING.

PubMed

Riemann, Bryan L; Davis, Sarah E; Huet, Kevin; Davies, George J

2016-02-01

Based on the frequency pushing and pulling patterns are used in functional activities, there is a need to establish an objective method of quantifying the muscle performance characteristics associated with these motions, particularly during the later stages of rehabilitation as criteria for discharge. While isokinetic assessment offers an approach to quantifying muscle performance, little is known about closed kinetic chain (CKC) isokinetic testing of the upper extremity (UE). To determine the intersession reliability of isokinetic upper extremity measurement of pushing and pulling peak force and average power at slow (0.24 m/s), medium (0.43 m/s) and fast (0.61 m/s) velocities in healthy young adults. The secondary purpose was to compare pushing and pulling peak force (PF) and average power (AP) between the upper extremity limbs (dominant, non-dominant) across the three velocities. Twenty-four physically active men and women completed a test-retest (>96 hours) protocol in order to establish isokinetic UE CKC reliability of PF and AP during five maximal push and pull repetitions at three velocities. Both limb and speed orders were randomized between subjects. High test-retest relative reliability using intraclass correlation coefficients (ICC2, 1) were revealed for PF (.91-.97) and AP (.85-.95) across velocities, limbs and directions. PF typical error (% coefficient of variation) ranged from 6.1% to 11.3% while AP ranged from 9.9% to 26.7%. PF decreased significantly (p < .05) as velocity increased whereas AP increased as velocity increased. PF and AP during pushing were significantly greater than pulling at all velocities, however the push-pull differences in PF became less as velocity increased. There were no significant differences identified between the dominant and nondominant limbs. Isokinetically derived UE CKC push-pull PF and AP are reliable measures. The lack of limb differences in healthy normal participants suggests that clinicians can consider bilateral comparisons when interpreting test performance. The increase in pushing PF and AP compared to pulling can be attributed to the muscles involved and the frequency that pushing patterns are used during functional activities. 3.

Toward automating Hammersmith pulled-to-sit examination of infants using feature point based video object tracking.

PubMed

Dogra, Debi P; Majumdar, Arun K; Sural, Shamik; Mukherjee, Jayanta; Mukherjee, Suchandra; Singh, Arun

2012-01-01

Hammersmith Infant Neurological Examination (HINE) is a set of tests used for grading neurological development of infants on a scale of 0 to 3. These tests help in assessing neurophysiological development of babies, especially preterm infants who are born before (the fetus reaches) the gestational age of 36 weeks. Such tests are often conducted in the follow-up clinics of hospitals for grading infants with suspected disabilities. Assessment based on HINE depends on the expertise of the physicians involved in conducting the examinations. It has been noted that some of these tests, especially pulled-to-sit and lateral tilting, are difficult to assess solely based on visual observation. For example, during the pulled-to-sit examination, the examiner needs to observe the relative movement of the head with respect to torso while pulling the infant by holding wrists. The examiner may find it difficult to follow the head movement from the coronal view. Video object tracking based automatic or semi-automatic analysis can be helpful in this case. In this paper, we present a video based method to automate the analysis of pulled-to-sit examination. In this context, a dynamic programming and node pruning based efficient video object tracking algorithm has been proposed. Pulled-to-sit event detection is handled by the proposed tracking algorithm that uses a 2-D geometric model of the scene. The algorithm has been tested with normal as well as marker based videos of the examination recorded at the neuro-development clinic of the SSKM Hospital, Kolkata, India. It is found that the proposed algorithm is capable of estimating the pulled-to-sit score with sensitivity (80%-92%) and specificity (89%-96%).

Bond Strength of Composite CFRP Reinforcing Bars in Timber

PubMed Central

Corradi, Marco; Righetti, Luca; Borri, Antonio

2015-01-01

The use of near-surface mounted (NSM) fibre-reinforced polymer (FRP) bars is an interesting method for increasing the shear and flexural strength of existing timber members. This article examines the behaviour of carbon FRP (CFRP) bars in timber under direct pull-out conditions. The objective of this experimental program is to investigate the bond strength between composite bars and timber: bars were epoxied into small notches made into chestnut and fir wood members using a commercially-available epoxy system. Bonded lengths varied from 150 to 300 mm. Failure modes, stress and strain distributions and the bond strength of CFRP bars have been evaluated and discussed. The pull-out capacity in NSM CFRP bars at the onset of debonding increased with bonded length up to a length of 250 mm. While CFRP bar’s pull-out was achieved only for specimens with bonded lengths of 150 and 200 mm, bar tensile failure was mainly recorded for bonded lengths of 250 and 300 mm. PMID:28793423

Effects of bond primers on bending strength and bonding of glass fibers in fiber-embedded maxillofacial silicone prostheses.

PubMed

Hatamleh, Muhanad M; Watts, David C

2011-02-01

To evaluate the effect of three commonly used bond primers on the bending strength of glass fibers and their bond strength to maxillofacial silicone elastomer after 360 hours of accelerated daylight aging. Eighty specimens were fabricated by embedding resin-impregnated fiber bundles (1.5-mm diameter, 20-mm long) into maxillofacial silicone elastomer M511 (Cosmesil). Twenty fiber bundles served as control and did not receive surface treatment with primers, whereas the remaining 60 fibers were treated with three primers (n = 20): G611 (Principality Medical), A-304 (Factor II), and A-330-Gold (Factor II). Forty specimens were dry stored at room temperature (23 ± 1°C) for 24 hours, and the remaining specimens were aged using an environmental chamber under accelerated exposure to artificial daylight for 360 hours. The aging cycle included continuous exposure to quartz-filtered visible daylight (irradiance 760 W/m(2) ) under an alternating weathering cycle (wet for 18 minutes, dry for 102 minutes). Pull-out tests were performed to evaluate bond strength between fiber bundles and silicone using a universal testing machine at 1 mm/min crosshead speed. A 3-point bending test was performed to evaluate the bending strength of the fiber bundles. One-way Analysis of Variance (ANOVA), Bonferroni post hoc test, and an independent t-test were carried out to detect statistical significances (p < 0.05). Mean (SD) values of maximum pull-out forces (N) before aging for groups: no primer, G611, A-304, A-330-G were: 13.63 (7.45), 20.44 (2.99), 22.06 (6.69), and 57.91 (10.15), respectively. All primers increased bond strength in comparison to control specimens (p < 0.05). Primer A-330-G showed the greatest increase among all primers (p < 0.05); however, bonding degraded after aging (p < 0.05), and pull-out forces were 13.58 (2.61), 6.17 (2.89), 6.95 (2.61), and 11.72 (3.03). Maximum bending strengths of fiber bundles at baseline increased after treatment with primers and light aging in comparison with control specimens (p < 0.05), and were in the range of 917.72 to 1095.25 and 1124.06 to 1596.68 MPa at both baseline and after 360 hours aging (p < 0.05). The use of A-330-G primer in conjunction with silicone Cosmesil M511 produced the greatest bond strength for silicone-glass fiber surfaces at baseline; however, bond strength was significantly degraded after accelerated daylight aging. Treatment with primer and accelerated daylight aging increased bending strength of glass fibers. © 2011 by The American College of Prosthodontists.

Physical and mechanical characterization of PLLA interference screws produced by two stage injection molding method.

PubMed

Sadeghi-Avalshahr, Ali Reza; Khorsand-Ghayeni, Mohammad; Nokhasteh, Samira; Molavi, Amir Mahdi; Sadeghi-Avalshahr, Mohammad

2016-12-01

The purpose of this study was to produce and evaluate different mechanical, physical and in vitro cell culture characteristics of poly(L-lactic) acid (PLLA) interference screws. This work will focus on evaluating the effect of two important parameters on operation of these screws, first the tunnel diameter which is one of the most important parameters during the operation and second the thermal behavior, the main effective characteristic in production process. In this work, PLLA screws were produced by a two-stage injection molding machine. For mechanical assessment of the produced screws, Polyurethane rigid foam was used as cancellous bone and polypropylene rope as synthetic graft to simulate bone and ligament in real situation. Different tunnel diameters including 7-10 mm were evaluated for fixation strength. When the tunnel diameter was changed from 10 to 9 mm, the pull-out force has increased to about 12 %, which is probably due to the aforementioned frictional forces, however, by reducing the tunnel diameter to 8 and 7 mm, the pull-out force reduced to 16 and 50 % for 8 and 7 mm tunnel diameter, respectively. The minimum and maximum pull-out force was obtained 160.57 and 506.86 N for 7 and 9 mm tunnel diameters, respectively. For physicochemical assay, Fourier transform infrared spectroscopy (FTIR), degradation test and differential scanning calorimetry (DSC) were carried out. The crystallinity (Xc) of samples were decreased considerably from 64.3 % before injection to 32.95 % after injection with two different crystallographic forms α' and α. probably due to the fast cooling rate at room temperature. In addition, MTT and cell attachment assays were utilized by MG63 osteoblast cell line, to evaluate the cytotoxicity of the produced screws. The results revealed no cytotoxicity effect.

E. C. Meyer, General, United States Army, Chief of Staff, June 1979-June 1983

DTIC Science & Technology

1983-01-01

equipment to to war if we are called upon to do so. it pro- that is more maintainable because you pull out vides you with ready access to the manpower...what artillery can do, or what an armed helicopter can do. But the ability to pull them QUESTION: General, "if" you were to get your 5 together, all...at long last pull tible as possible. Have you read General Sir John intelligence services into organizations respon- Hackett’s book, The Third World

Evaluation of sulfate reduction at experimentally induced mixing interfaces using small-scale push-pull tests in an aquifer-wetland system

USGS Publications Warehouse

Kneeshaw, T.A.; McGuire, J.T.; Smith, E.W.; Cozzarelli, I.M.

2007-01-01

This paper presents small-scale push-pull tests designed to evaluate the kinetic controls on SO42 - reduction in situ at mixing interfaces between a wetland and aquifer impacted by landfill leachate at the Norman Landfill research site, Norman, OK. Quantifying the rates of redox reactions initiated at interfaces is of great interest because interfaces have been shown to be zones of increased biogeochemical transformations and thus may play an important role in natural attenuation. To mimic the aquifer-wetland interface and evaluate reaction rates, SO42 --rich anaerobic aquifer water (??? 100 mg / L SO42 -) was introduced into SO42 --depleted wetland porewater via push-pull tests. Results showed SO42 - reduction was stimulated by the mixing of these waters and first-order rate coefficients were comparable to those measured in other push-pull studies. However, rate data were complex involving either multiple first-order rate coefficients or a more complex rate order. In addition, a lag phase was observed prior to SO42 - reduction that persisted until the mixing interface between test solution and native water was recovered, irrespective of temporal and spatial constraints. The lag phase was not eliminated by the addition of electron donor (acetate) to the injected test solution. Subsequent push-pull tests designed to elucidate the nature of the lag phase support the importance of the mixing interface in controlling terminal electron accepting processes. These data suggest redox reactions may occur rapidly at the mixing interface between injected and native waters but not in the injected bulk water mass. Under these circumstances, push-pull test data should be evaluated to ensure the apparent rate is actually a function of time and that complexities in rate data be considered. ?? 2007 Elsevier Ltd. All rights reserved.

Commercial Scholarship: Spinning Physics Research into a Business Enterprise

NASA Astrophysics Data System (ADS)

Butler, Orville

2013-03-01

The American Institute of Physics' Center for History of Physics has conducted a three year NSF funded study of physicist entrepreneurs during which we interviewed 140 physicists who have founded ninety-one startups. Forty of those companies have spun research out of twenty-some universities. Startups spun out of university research tend to be technology push companies, creating new potentially disruptive technologies for which markets do not yet clearly exist, in contrast to market pull companies founded to address innovations responding to market demands. This paper addresses the unique issues found in university spinout companies and their responses to them. While technology push companies are generally considered to be higher risk compared to market pull companies, the university spinouts in our study had a higher rate of both SBIR and venture capital funding than did the market pull companies in our study.

Square-lashing technique in segmental spinal instrumentation: a biomechanical study.

PubMed

Arlet, Vincent; Draxinger, Kevin; Beckman, Lorne; Steffen, Thomas

2006-07-01

Sublaminar wires have been used for many years for segmental spinal instrumentation in scoliosis surgery. More recently, stainless steel wires have been replaced by titanium cables. However, in rigid scoliotic curves, sublaminar wires or simple cables can either brake or pull out. The square-lashing technique was devised to avoid complications such as cable breakage or lamina cutout. The purpose of the study was therefore to test biomechanically the pull out and failure mode of simple sublaminar constructs versus the square-lashing technique. Individual vertebrae were subjected to pullout testing having one of two different constructs (single loop and square lashing) using either monofilament wire or multifilament cables. Four different methods of fixation were therefore tested: single wire construct, square-lashing wiring construct, single cable construct, and square-lashing cable construct. Ultimate failure load and failure mechanism were recorded. For the single wire the construct failed 12/16 times by wire breakage with an average ultimate failure load of 793 N. For the square-lashing wire the construct failed with pedicle fracture in 14/16, one bilateral lamina fracture, and one wire breakage. Ultimate failure load average was 1,239 N For the single cable the construct failed 12/16 times due to cable breakage (average force 1,162 N). 10/12 of these breakages were where the cable looped over the rod. For the square-lashing cable all of these constructs (16/16) failed by fracture of the pedicle with an average ultimate failure load of 1,388 N. The square-lashing construct had a higher pullout strength than the single loop and almost no cutting out from the lamina. The square-lashing technique with cables may therefore represent a new advance in segmental spinal instrumentation.

Investigation of the influence of coolant-lubricant modification on selected effects of pull broaching

NASA Astrophysics Data System (ADS)

Adamczuk, Krzysztof; Legutko, Stanisław; Laber, Alicja; Serwa, Wojciech

2017-10-01

The paper presents the results of testing the wear of the tool (pull broach) and a gear wheel splineway surface roughness after the friction node of pull broach/gear wheel (CuSn12Ni2) had been lubricated with metal machining oil and the same oil modified with chemically active exploitation additive. To designate the influence of modifying metal machining oil by the exploitation additive on the lubricating properties, anti-wear and antiseizure indicators have been appointed. Exploitation tests have proved purposefulness of modifying metal machining oil. Modification of the lubricant has contributed to reduction of the wear of the tools - pull broaches and to reduction of roughness of the splineway surfaces.

The Highly-Automated Airplane: Its Impact on Aviation Safety and an Analysis of Training Philosophy.

DTIC Science & Technology

1997-06-01

equipment. This means more than just knowing how to program the device and being familiar with the functions of varying modes (Patrick, 1996:18). 33...the function that I wanted to use or modify in a flight plan." "Initially it is extremely difficult to figure out exactly how to program or pull up...commented: "Getting used to the EFIS display was the hardest. Initially it is extremely difficult to figure out exactly how to program or pull up the

The anomaly in a breakthrough curve of a single well "push-pull" tracer test: A density driven effect?

NASA Astrophysics Data System (ADS)

Zeilfelder, Sarah; Hebig, Klaus; Ito, Narimitsu; Machida, Isao; Scheytt, Traugott; Marui, Atsunao

2013-04-01

What method is appropriate to investigate an aquifer when there is only one well available? A single well "push-pull" tracer test (PP Test) may be a suitable method in order to characterize an aquifer and to obtain information about the hydraulic and chemical properties when only one well is available for the investigations. In a PP test, a test solution that contains a known amount of solutes and a conservative tracer is injected into the aquifer ("push") and extracted afterwards ("pull"). Optionally, the test solution is flushed out of the well and the casing with untreated test solution with a so called "chaser" before being extracted. Also between the injection and the extraction phase a drifting time may be included. The breakthrough of the tracer during the extraction phase is measured and used for analyses and interpretation. In the last three years, several PP Test campaigns were conducted at two different test sites in Japan (Hebig et al. 2011, Zeilfelder et al. 2012). The aim was to investigate the applicability of the PP Test method in different geological settings and in different types of aquifers. The latest field campaign thus focussed on the question how variations of the setup are influencing the breakthrough curve of the PP Test in order to develop and enhance this method. Also the standardization of the PP Test was an aim of this study. During the campaign, a total of seven PP Tests were performed, while only single aspects of the setup were varied from test to test. The tests differed in injection and extraction rate, in the salinity of the injected test solution and in the use of a chaser solution. The general shapes of the breakthrough curves were similar and conclusions about the repeatability of the PP Test could be drawn. However, a sharp anomaly was observed in the breakthrough curve of one specific setup type. By repeating this PP test under the same boundary conditions, we were able to recreate the anomaly and could exclude any technical aspects as a source. In this version of the PP test higher salinized test solution was injected into the aquifer. There are several hypotheses that could explain the behavior of the breakthrough curves of the tracer in this test design. Of all the possibilities (like sorption processes, unexpected tracer reactions, inhomogeneities in the aquifer, influence of the well design), we assume that ion exchange processes and density driven flow are the main reasons for the repeatedly observed anomaly. References: Hebig, K.H., Ito, N., Scheytt, T.J. & Marui, A. (2011). Hydraulic and hydrochemical characterization of deep coastal sedimentary basins by single-well Push-Pull tests. GSA Annual Meeting, 9-12 October 2011, Minneapolis, USA. Zeilfelder, S., Ito, N., Marui, A., Hebig, K. & Scheytt, T. (2012). Push-Pull-Test und Tracer-Test in einem tiefen Grundwasserleiter in Kameoka, Japan. Kurzfassung in: Liedl, R., Burghardt, D., Simon, E., Reimann, T. & Kaufmann-Knoke (Hg.). Grundwasserschutz und Grundwassernutzung. Tagung der Fachsektion Hydrogeologie in der DGG (FH-DGG). 16. - 20. Mai 2012, Dresden. Kurfassungen der Vorträge und Poster. Schriftenreihe der DGG, Heft 78, S. 192.

Mechanical and biological evaluations of beta-tricalcium phosphate/silicone rubber composite as a novel soft-tissue implant.

PubMed

Zhang, Yi-ming; Wang, Shao-liang; Lei, Ze-yuan; Fan, Dong-li

2009-09-01

Although silicone rubber (SR) implants are most commonly used and effective for soft-tissue augmentation, they still have been implicated in many adverse reactions. To overcome this problem, a novel composite beta-tricalcium phosphate/silicone rubber (beta-TCP/SR) was prepared by adding beta-TCP into a SR matrix. This study was to evaluate its application potential by investigating the mechanical properties and biocompatibility of beta-TCP/SR. Mechanical properties, including Shore A hardness and tensile strength, were evaluated with 3-mm-thick samples and a universal testing machine. Cytocompatibility tests were conducted in vitro using 0.2-mm-thick beta-TCP/SR samples by seeding fibroblasts onto different samples. Soft-tissue response to beta-TCP/SR and pull-out measurements were investigated 4 weeks and 24 weeks after implantation. The main mechanical properties were all significantly changed after mixing beta-TCP into the SR matrix, except for tearing strength. The cytocompatibility test showed enhanced adhesion and proliferation of fibroblasts onto beta-TCP/SR. Fibrous tissue ingrowth after resorption of beta-TCP was observed by in vivo histologic analysis. The peri-implant capsules in the beta-TCP/SR group were thinner than in the SR group 24 weeks after implantation. In a 24-week test, the maximum force required to pull out the beta-TCP/SR sheet was about six times greater than that needed for SR. Although some mechanical properties were significantly changed, the results of the cytocompatibility test and in vivo animal study still suggest that beta-TCP/SR may be more suitable as a soft-tissue implant than SR and has the potential to be used in plastic surgery.

Acoustic emission monitoring of polymer composite materials

NASA Technical Reports Server (NTRS)

Bardenheier, R.

1981-01-01

The techniques of acoustic emission monitoring of polymer composite materials is described. It is highly sensitive, quasi-nondestructive testing method that indicates the origin and behavior of flaws in such materials when submitted to different load exposures. With the use of sophisticated signal analysis methods it is possible the distinguish between different types of failure mechanisms, such as fiber fracture delamination or fiber pull-out. Imperfections can be detected while monitoring complex composite structures by acoustic emission measurements.

Physical Employment Standards for UK Firefighters

PubMed Central

Stevenson, Richard D.M.; Siddall, Andrew G.; Turner, Philip F.J.; Bilzon, James L.J.

2017-01-01

Objective: The aim of this study was to assess sensitivity and specificity of surrogate physical ability tests as predictors of criterion firefighting task performance and to identify corresponding minimum muscular strength and endurance standards. Methods: Fifty-one (26 male; 25 female) participants completed three criterion tasks (ladder lift, ladder lower, ladder extension) and three corresponding surrogate tests [one-repetition maximum (1RM) seated shoulder press; 1RM seated rope pull-down; repeated 28 kg seated rope pull-down]. Surrogate test standards were calculated that best identified individuals who passed (sensitivity; true positives) and failed (specificity; true negatives) criterion tasks. Results: Best sensitivity/specificity achieved were 1.00/1.00 for a 35 kg seated shoulder press, 0.79/0.92 for a 60 kg rope pull-down, and 0.83/0.93 for 23 repetitions of the 28 kg rope pull-down. Conclusions: These standards represent performance on surrogate tests commensurate with minimum acceptable performance of essential strength-based occupational tasks in UK firefighters. PMID:28045801

Flexible fiber-reinforced composites with improved interfacial adhesion by mussel-inspired polydopamine and poly(methyl methacrylate) coating.

PubMed

Yi, Mi; Sun, Hongyang; Zhang, Hongcheng; Deng, Xuliang; Cai, Qing; Yang, Xiaoping

2016-01-01

To obtain a kind of light-curable fiber-reinforced composite for dental restoration, an excellent interfacial adhesion between the fiber and the acrylate resin matrix is quite essential. Herein, surface modification on glass fibers were carried out by coating them with poly(methyl methacrylate) (PMMA), polydopamine (PDA), or both. The PMMA or PDA coating was performed by soaking fibers in PMMA/acetone solution or dopamine aqueous solution. PDA/PMMA co-coated glass fibers were obtained by further soaking PDA-coated fibers in PMMA/acetone solution. These modified fibers were impregnated with bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) (5:5, w/w) dental resin at a volume fraction of 75%, using unmodified fibers as reference. Light-cured specimens were submitted to evaluations including flexural properties, morphological observation, dynamic mechanical thermal analysis (DMTA) and pull-out test. In comparison with unmodified glass fibers, all the modified glass fibers showed enhancements in flexural strength and modulus of Bis-GMA/TEGDMA resin composites. Results of DMTA and pull-out tests confirmed that surface modification had significantly improved the interfacial adhesion between the glass fiber and the resin matrix. Particularly, the PDA/PMMA co-coated glass fibers displayed the most efficient reinforcement and the strongest interfacial adhesion due to the synergetic effects of PDA and PMMA. It indicated that co-coating method was a promising approach in modifying the interfacial compatibility between inorganic glass fiber and organic resin matrix. Copyright © 2015 Elsevier B.V. All rights reserved.

Method of measuring metal coating adhesion

DOEpatents

Roper, J.R.

A method for measuring metal coating adhesion to a substrate material comprising the steps of preparing a test coupon of substrate material having the metal coating applied to one surface thereof, applying a second metal coating of gold or silver to opposite surfaces of the test coupon by hot hollow cathode process, applying a coating to one end of each of two pulling rod members, joining the coated ends of the pulling rod members to said opposite coated surfaces of the test coupon by a solid state bonding technique and finally applying instrumented static tensile loading to the pulling rod members until fracture of the metal coating adhesion to the substrate material occurs.

Method of measuring metal coating adhesion

DOEpatents

Roper, John R.

1985-01-01

A method for measuring metal coating adhesion to a substrate material comprising the steps of preparing a test coupon of substrate material having the metal coating applied to one surface thereof, applying a second metal coating of gold or silver to opposite surfaces of the test coupon by hot hollow cathode process, applying a coating to one end of each of two pulling rod members, joining the coated ends of the pulling rod members to said opposite coated surfaces of the test coupon by a solid state bonding technique and finally applying instrumented static tensile loading to the pulling rod members until fracture of the metal coating adhesion to the substrate material occurs.

Development of a model for occipital fixation--validation of an analogue bone material.

PubMed

Mullett, H; O'Donnell, T; Felle, P; O'Rourke, K; FitzPatrick, D

2002-01-01

Several implant systems may be used to fuse the skull to the upper cervical spine (occipitocervical fusion). Current biomechanical evaluation is restricted by the limitations of human cadaveric specimens. This paper describes the design and validation of a synthetic testing model of the occipital bone. Data from thickness measurement and pull-out strength testing of a series of human cadaveric skulls was used in the design of a high-density rigid polyurethane foam model. The synthetic occipital model demonstrated repeatable and consistent morphological and biomechanical properties. The model provides a standardized environment for evaluation of occipital implants.

40 CFR 60.685 - Test methods and procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... average of three glass pull rate (Pi) determinations taken at intervals of at least 30 minutes during each run. The individual glass pull rates (Pi) shall be computed using the following equation: Pi = K′ Ls Wm M [1.0−(LOI/100)] where: Pi = glass pull rate at interval “i”, Mg/hr (ton/hr). Ls = line speed, m...

Manipulator for hollow objects

DOEpatents

Cawley, William E.; Frantz, Charles E.

1977-01-01

A device for gripping the interior of a tubular object to pull it out of a body in which it has become stuck includes an expandable rubber tube having a plurality of metal cables lodged in the exterior of the rubber tube so as to protrude slightly therefrom, means for inflating the tube and means for pulling the tube longitudinally of the tubular object.

The "Push-Pull" Approach to Fast-Track Management Development: A Case Study in Scientific Publishing

ERIC Educational Resources Information Center

Fojt, Martin; Parkinson, Stephen; Peters, John; Sandelands, Eric

2008-01-01

Purpose: The purpose of this paper is to explore how a medium sized business has addressed what it has termed a "push-pull" method of management and organization development, based around an action learning approach. Design/methodology/approach: The paper sets out a methodology that other SMEs might look to replicate in their management and…

Do dual-thread orthodontic mini-implants improve bone/tissue mechanical retention?

PubMed

Lin, Yang-Sung; Chang, Yau-Zen; Yu, Jian-Hong; Lin, Chun-Li

2014-12-01

The aim of this study was to understand whether the pitch relationship between micro and macro thread designs with a parametrical relationship in a dual-thread mini-implant can improve primary stability. Three types of mini-implants consisting of single-thread (ST) (0.75 mm pitch in whole length), dual-thread A (DTA) with double-start 0.375 mm pitch, and dual-thread B (DTB) with single-start 0.2 mm pitch in upper 2-mm micro thread region for performing insertion and pull-out testing. Histomorphometric analysis was performed in these specimens in evaluating peri-implant bone defects using a non-contact vision measuring system. The maximum inserted torque (Tmax) in type DTA was found to be the smallest significantly, but corresponding values found no significant difference between ST and DTB. The largest pull-out strength (Fmax) in the DTA mini-implant was found significantly greater than that for the ST mini-implant regardless of implant insertion orientation. Mini-implant engaged the cortical bone well as observed in ST and DTA types. Dual-thread mini-implant with correct micro thread pitch (parametrical relationship with macro thread pitch) in the cortical bone region can improve primary stability and enhanced mechanical retention.

Cable Terminations for the BSURE (Barking Sands Underwater Range Expansion) Terminal and Transmission Units (TATU). Design Review Team Report.

DTIC Science & Technology

1985-01-01

One, a cable termination pull out and two, leakage. It is felt that both of these problems have been solved. The cable termiration pullout problem...nm selctroicse~I -. V~- 30.3 Z? Ul.T Casio Ca" inOS Allow waer to tam. feai Mone 11 l i"f MM Goali (30.321) -= 9to75 % col roo NMI V023 ’..ca...t-he third typ. of failure, an SD cable pulled out of termination. This was obviously not caused by a Morrison seal or an 0-ring. it appears

Push-pull tracer tests: Their information content and use for characterizing non-Fickian, mobile-immobile behavior: INFORMATION CONTENT OF PUSH-PULL TESTS

DOE PAGES

Hansen, Scott K.; Berkowitz, Brian; Vesselinov, Velimir V.; ...

2016-12-01

Path reversibility and radial symmetry are often assumed in push-pull tracer test analysis. In reality, heterogeneous flow fields mean that both assumptions are idealizations. In this paper, to understand their impact, we perform a parametric study which quantifies the scattering effects of ambient flow, local-scale dispersion, and velocity field heterogeneity on push-pull breakthrough curves and compares them to the effects of mobile-immobile mass transfer (MIMT) processes including sorption and diffusion into secondary porosity. We identify specific circumstances in which MIMT overwhelmingly determines the breakthrough curve, which may then be considered uninformative about drift and local-scale dispersion. Assuming path reversibility, wemore » develop a continuous-time-random-walk-based interpretation framework which is flow-field-agnostic and well suited to quantifying MIMT. Adopting this perspective, we show that the radial flow assumption is often harmless: to the extent that solute paths are reversible, the breakthrough curve is uninformative about velocity field heterogeneity. Our interpretation method determines a mapping function (i.e., subordinator) from travel time in the absence of MIMT to travel time in its presence. A mathematical theory allowing this function to be directly “plugged into” an existing Laplace-domain transport model to incorporate MIMT is presented and demonstrated. Algorithms implementing the calibration are presented and applied to interpretation of data from a push-pull test performed in a heterogeneous environment. A successful four-parameter fit is obtained, of comparable fidelity to one obtained using a million-node 3-D numerical model. In conclusion, we demonstrate analytically and numerically how push-pull tests quantifying MIMT are sensitive to remobilization, but not immobilization, kinetics.« less

Push-pull tracer tests: Their information content and use for characterizing non-Fickian, mobile-immobile behavior: INFORMATION CONTENT OF PUSH-PULL TESTS

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

Hansen, Scott K.; Berkowitz, Brian; Vesselinov, Velimir V.

Path reversibility and radial symmetry are often assumed in push-pull tracer test analysis. In reality, heterogeneous flow fields mean that both assumptions are idealizations. In this paper, to understand their impact, we perform a parametric study which quantifies the scattering effects of ambient flow, local-scale dispersion, and velocity field heterogeneity on push-pull breakthrough curves and compares them to the effects of mobile-immobile mass transfer (MIMT) processes including sorption and diffusion into secondary porosity. We identify specific circumstances in which MIMT overwhelmingly determines the breakthrough curve, which may then be considered uninformative about drift and local-scale dispersion. Assuming path reversibility, wemore » develop a continuous-time-random-walk-based interpretation framework which is flow-field-agnostic and well suited to quantifying MIMT. Adopting this perspective, we show that the radial flow assumption is often harmless: to the extent that solute paths are reversible, the breakthrough curve is uninformative about velocity field heterogeneity. Our interpretation method determines a mapping function (i.e., subordinator) from travel time in the absence of MIMT to travel time in its presence. A mathematical theory allowing this function to be directly “plugged into” an existing Laplace-domain transport model to incorporate MIMT is presented and demonstrated. Algorithms implementing the calibration are presented and applied to interpretation of data from a push-pull test performed in a heterogeneous environment. A successful four-parameter fit is obtained, of comparable fidelity to one obtained using a million-node 3-D numerical model. In conclusion, we demonstrate analytically and numerically how push-pull tests quantifying MIMT are sensitive to remobilization, but not immobilization, kinetics.« less

Influence of molecular designs on polaronic and vibrational transitions in a conjugated push-pull copolymer

NASA Astrophysics Data System (ADS)

Cobet, Christoph; Gasiorowski, Jacek; Menon, Reghu; Hingerl, Kurt; Schlager, Stefanie; White, Matthew S.; Neugebauer, Helmut; Sariciftci, N. Serdar; Stadler, Philipp

2016-10-01

Electron-phonon interactions of free charge-carriers in doped pi-conjugated polymers are conceptually described by 1-dimensional (1D) delocalization. Thereby, polaronic transitions fit the 1D-Froehlich model in quasi-confined chains. However, recent developments in conjugated polymers have diversified the backbones to become elaborate heterocylcic macromolecules. Their complexity makes it difficult to investigate the electron-phonon coupling. In this work we resolve the electron-phonon interactions in the ground and doped state in a complex push-pull polymer. We focus on the polaronic transitions using in-situ spectroscopy to work out the differences between single-unit and push-pull systems to obtain the desired structural- electronic correlations in the doped state. We apply the classic 1D-Froehlich model to generate optical model fits. Interestingly, we find the 1D-approach in push-pull polarons in agreement to the model, pointing at the strong 1D-character and plain electronic structure of the push-pull structure. In contrast, polarons in the single-unit polymer emerge to a multi- dimensional problem difficult to resolve due to their anisotropy. Thus, we report an enhancement of the 1D-character by the push-pull concept in the doped state - an important view in light of the main purpose of push-pull polymers for photovoltaic devices.

Equivalence Reliability among the FITNESSGRAM[R] Upper-Body Tests of Muscular Strength and Endurance

ERIC Educational Resources Information Center

Sherman, Todd; Barfield, J. P.

2006-01-01

This study was designed to investigate the equivalence reliability between the suggested FITNESSGRAM[R] muscular strength and endurance test, the 90[degrees] push-up (PSU), and alternate FITNESSGRAM[R] tests of upper-body strength and endurance (i.e., modified pull-up [MPU], flexed-arm hang [FAH], and pull-up [PU]). Children (N = 383) in Grades 3…

Interpretation of the lime column penetration test

NASA Astrophysics Data System (ADS)

Liyanapathirana, D. S.; Kelly, R. B.

2010-06-01

Dry soil mix (DSM) columns are used to reduce the settlement and to improve the stability of embankments constructed on soft clays. During construction the shear strength of the columns needs to be confirmed for compliance with technical assumptions. A specialized blade shaped penetrometer known as the lime column probe, has been developed for testing DSM columns. This test can be carried out as a pull out resistance test (PORT) or a push in resistance test (PIRT). The test is considered to be more representative of average column shear strength than methods that test only a limited area of the column. Both PORT and PIRT tests require empirical correlations of measured resistance to an absolute measure of shear strength, in a similar manner to the cone penetration test. In this paper, finite element method is used to assess the probe factor, N, for the PORT test. Due to the large soil deformations around the probe, an Arbitrary Lagrangian Eulerian (ALE) based finite element formulation has been used. Variation of N with rigidity index and the friction at the probe-soil interface are investigated to establish a range for the probe factor.

40 CFR 60.685 - Test methods and procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... average of three glass pull rate (Pi) determinations taken at intervals of at least 30 minutes during each run. The individual glass pull rates (Pi) shall be computed using the following equation: Pi=K′ Ls Wm M [1.0−(LOI/100)] where: Pi=glass pull rate at interval “i”, Mg/hr (ton/hr). Ls=line speed, m/min...

40 CFR 60.685 - Test methods and procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... average of three glass pull rate (Pi) determinations taken at intervals of at least 30 minutes during each run. The individual glass pull rates (Pi) shall be computed using the following equation: Pi=K′ Ls Wm M [1.0−(LOI/100)] where: Pi=glass pull rate at interval “i”, Mg/hr (ton/hr). Ls=line speed, m/min...

40 CFR 60.685 - Test methods and procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... average of three glass pull rate (Pi) determinations taken at intervals of at least 30 minutes during each run. The individual glass pull rates (Pi) shall be computed using the following equation: Pi=K′ Ls Wm M [1.0−(LOI/100)] where: Pi=glass pull rate at interval “i”, Mg/hr (ton/hr). Ls=line speed, m/min...

40 CFR 60.685 - Test methods and procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... average of three glass pull rate (Pi) determinations taken at intervals of at least 30 minutes during each run. The individual glass pull rates (Pi) shall be computed using the following equation: Pi=K′ Ls Wm M [1.0−(LOI/100)] where: Pi=glass pull rate at interval “i”, Mg/hr (ton/hr). Ls=line speed, m/min...

Cyanoacrylate tissue adhesives - effective securement technique for intravascular catheters: in vitro testing of safety and feasibility.

PubMed

Simonova, G; Rickard, C M; Dunster, K R; Smyth, D J; McMillan, D; Fraser, J F

2012-05-01

Partial or complete dislodgement of intravascular catheters remains a significant problem in hospitals despite current securement methods. Cyanoacrylate tissue adhesives (TA) are used to close skin wounds as an alternative to sutures. These adhesives have high mechanical strength and can remain in situ for several days. This study investigated in vitro use of TAs in securing intravascular catheters (IVC). We compared two adhesives for interaction with IVC material, comparing skin glues with current securement methods in terms of their ability to prevent IVC dislodgement and inhibit microbial growth. Two TAs (Dermabond, Ethicon Inc. and Histoacryl, B. Braun) and three removal agents (Remove™, paraffin and acetone) were tested for interaction with IVC material by use of tensile testing. TAs were also compared against two polyurethane (standard and bordered) dressings (Tegaderm™ 1624 and 1633, 3M Australia Pty Ltd) and an external stabilisation device (Statlock, Bard Medical, Covington) against control (unsecured IVCs) for ability to prevent pull-out of 16 G peripheral IVCs from newborn fresh porcine skin. Agar media containing pH-sensitive dye was used to assess antimicrobial properties of TAs and polyurethane dressings to inhibit growth of Staphylococcus aureus and Staphylococcus epidermidis. Neither TA weakened the IVCs (P >0.05). Of removal agents, only acetone was associated with a significant decrease in IVC strength (P <0.05). Both TAs and Statlock significantly increased the pull-out force (P <0.01). TA was quick and easy to apply to IVCs, with no irritation or skin damage noted on removal and no bacterial colony growth under either TA.

Ultrasonic Spot Welding of a Rare-Earth Containing ZEK100 Magnesium Alloy: Effect of Welding Energy

NASA Astrophysics Data System (ADS)

Macwan, A.; Chen, D. L.

2016-04-01

Ultrasonic spot welding was used to join a low rare-earth containing ZEK100 Mg alloy at different levels of welding energy, and tensile lap shear tests were conducted to evaluate the failure strength in relation to the microstructural changes. It was observed that dynamic recrystallization occurred in the nugget zone; the grain size increased and microhardness decreased with increasing welding energy arising from the increasing interface temperature and strain rate. The weld interface experienced severe plastic deformation at a high strain rate from ~500 to ~2100 s-1 with increasing welding energy from 500 to 2000 J. A relationship between grain size and Zener-Hollomon parameter, and a Hall-Petch-type relationship between microhardness and grain size were established. The tensile lap shear strength and failure energy were observed to first increase with increasing welding energy, reach the maximum values at 1500 J, and then decrease with a further increase in the welding energy. The samples welded at a welding energy ≤1500 J exhibited an interfacial failure mode, while nugget pull-out occurred in the samples welded at a welding energy above 1500 J. The fracture surfaces showed typical shear failure. Low-temperature tests at 233 K (-40 °C) showed no significant effect on the strength and failure mode of joints welded at the optimal welding energy of 1500 J. Elevated temperature tests at 453 K (180 °C) revealed a lower failure load but a higher failure energy due to the increased deformability, and showed a mixed mode of partial interfacial failure and partial nugget pull-out.

EFFECT OF EUGENOL-BASED ENDODONTIC SEALER ON THE ADHESION OF INTRARADICULAR POSTS CEMENTED AFTER DIFFERENT PERIODS

PubMed Central

Dias, Larissa Lustosa Lima; Giovani, Alessandro Rogério; Sousa, Yara Teresinha Corrêa Silva; Vansan, Luiz Pascoal; Alfredo, Edson; Sousa-Neto, Manoel Damião; Paulino, Silvana Maria

2009-01-01

Objective: This study evaluated in vitro the influence of an eugenol-based sealer (EndoFill) on the retention of stainless steel prefabricated posts cemented with zinc phosphate and resin-based (Panavia F) cements after different periods of root canal obturation, using the pull-out test. Material and methods: Sixty upper canines were decoronated and the roots were embedded in resin blocks. The specimens were distributed into 3 groups, according to the period elapsed between canal obturation and post cementation: Group I - immediately; Group II - 72 h and Group III - 4 months. The groups were subdivided according to the type of cement used for post cementation: A - zinc phosphate and B - Panavia F. Following the experimental periods, specimens were subjected to pull- out test in an Instron machine with application of tensile force at a crosshead speed of 0.5 mm/min until post dislodgement. The maximum forces required for post removal were recorded (kN) and means were subjected to statistical analysis by 2-way ANOVA and Tukey-Kramer test (α=0.001) Results: There were statistically significant differences (p<0.01) between the posts cemented with zinc phosphate cement (0.2112 kN) and Panavia F (0.0501 kN). However, no statistically significant differences (p>0.05) were found between the three post cementation periods, regardless of the cement. Conclusions: It was concluded that the eugenol-based sealer influenced the tensile strength of the posts cemented with the resin cement, but had no influence on the time waited between root canal obturation and post space preparation/post cementation. PMID:20027430

A computer-guided minimally-invasive technique for orthodontic forced eruption of impacted canines.

PubMed

BERTELè, Matteo; Minniti, Paola P; Dalessandri, Domenico; Bonetti, Stefano; Visconti, Luca; Paganelli, Corrado

2016-06-01

The aim of this study was to develop a computer-guided minimally-invasive protocol for the surgical application of an orthodontic traction during the forced eruption of an impacted canine. 3Diagnosys® software was used to evaluate impacted canines position and to plan the surgical access, taking into account soft and hard tissues thickness, orthodontic traction path and presence of possible obstacles. Geomagic® software was used for reverse engineering and RhinocerosTM software was employed as three-dimensional modeller in preparing individualized surgical guides. Surgical access was gained flapless through the use of a mucosal punch for soft tissues, followed by a trephine bur with a pre-adjusted stop for bone path creation. A diamond bur mounted on SONICflex® 2003/L handpiece was used to prepare a 2-mm-deep calibrated hole into the canine enamel where a titanium screw connected with a stainless steel ligature was screwed. In-vitro pull-out tests, radiological and SEM analysis were realized in order to investigate screw stability and position. In two out of ten samples the screw was removed after the application of a 1-kg pull-out force. Radiological and SEM analysis demonstrated that all the screws were inserted into the enamel without affecting dentine integrity. This computer-guided minimally-invasive technique allowed a precise and reliable positioning of screws utilized during the orthodontic traction of impacted canines.

The effect of aspect ratio on adhesion and stiffness for soft elastic fibres

PubMed Central

Aksak, Burak; Hui, Chung-Yuen; Sitti, Metin

2011-01-01

The effect of aspect ratio on the pull-off stress and stiffness of soft elastic fibres is studied using elasticity and numerical analysis. The adhesive interface between a soft fibre and a smooth rigid surface is modelled using the Dugdale–Barenblatt model. Numerical simulations show that, while pull-off stress increases with decreasing aspect ratio, fibres get stiffer. Also, for sufficiently low aspect ratio fibres, failure occurs via the growth of internal cracks and pull-off stress approaches the intrinsic adhesive strength. Experiments carried out with various aspect ratio polyurethane elastomer fibres are consistent with the numerical simulations. PMID:21227962

Root reinforcement and its contribution to slope stability in the Western Ghats of Kerala, India

NASA Astrophysics Data System (ADS)

Lukose Kuriakose, Sekhar; van Beek, L. P. H.

2010-05-01

The Western Ghats of Kerala, India is prone to shallow landslides and consequent debris flows. An earlier study (Kuriakose et al., DOI:10.1002/esp.1794) with limited data had already demonstrated the possible effects of vegetation on slope hydrology and stability. Spatially distributed root cohesion is one of the most important data necessary to assess the effects of anthropogenic disturbances on the probability of shallow landslide initiation, results of which are reported in sessions GM6.1 and HS13.13/NH3.16. Thus it is necessary to the know the upper limits of reinforcement that the roots are able to provide and its spatial and vertical distribution in such an anthropogenically intervened terrain. Root tensile strength and root pull out tests were conducted on nine species of plants that are commonly found in the region. They are 1) Rubber (Hevea Brasiliensis), 2) Coconut Palm (Cocos nucifera), 3) Jackfruit trees (Artocarpus heterophyllus), 4) Teak (Tectona grandis), 5) Mango trees (Mangifera indica), 6) Lemon grass (Cymbopogon citratus), 7) Gambooge (Garcinia gummi-gutta), 8) Coffee (Coffea Arabica) and 9) Tea (Camellia sinensis). About 1500 samples were collected of which only 380 could be tested (in the laboratory) due to breakage of roots during the tests. In the successful tests roots failed in tension. Roots having diameters between 2 mm and 12 mm were tested. Each sample tested had a length of 15 cm. Root pull out tests were conducted in the field. Root tensile strength vs root diameter, root pull out strength vs diameter, root diameter vs root depth and root count vs root depth relationships were derived. Root cohesion was computed for nine most dominant plants in the region using the perpendicular root model of Wu et al. (1979) modified by Schimidt et al. (2001). A soil depth map was derived using regression kriging as suggested by Kuriakose et al., (doi:10.1016/j.catena.2009.05.005) and used along with the land use map of 2008 to distribute the computed root tensile strength both vertically and spatially. Root cohesion varies significantly with the type of land use and the depth of soil. The computation showed that a maximum root reinforcement of 40 kPa was available in the first 30 cm of soil while exponentially decreased with depth to just about 3 kPa at 3 m depth. Mixed crops land use unit had the maximum root cohesion while fallow land, degraded forest and young rubber plantation had the lowest root reinforcement. These are the upper limits of root reinforcement that the vegetation can provide. When the soil is saturated, the bond between soil and roots reduces and thus the applicable root reinforcement is limited by the root pullout strength. Root reinforcement estimated from pullout strength vs diameter relationships was significantly lower than those estimated from tensile strength vs diameter relationships.

Corrosion Induced Loss of Capacity of Post Tensioned Seven Wire Strand Cable Used in Multistrand Anchor Systems Installed at Corps Projects

DTIC Science & Technology

2016-12-01

Universal Test Machine. .................. 7 Figure 2.2. Pull-test results of PT seven-wire strand cable surrounded by a quickset, steel - reinforced epoxy...13 Figure 2.7. Pull-test results of PT seven-wire strand cable surrounded by a quickset, steel - reinforced...surrounded by a thick layer of quickset, steel -reinforced epoxy and with 40% reduced wedges. ....................................................... 15

Button fixation technique for Achilles tendon reinsertion: a biomechanical study.

PubMed

Awogni, David; Chauvette, Guillaume; Lemieux, Marie-Line; Balg, Frédéric; Langelier, Ève; Allard, Jean-Pascal

2014-01-01

Chronic insertional tendinopathy of the Achilles tendon is a frequent and disabling pathologic entity. Operative treatment is indicated for patients for whom nonoperative management has failed. The treatment can consist of the complete detachment of the tendon insertion and extensive debridement. We biomechanically tested a new operative technique that uses buttons for fixation of the Achilles tendon insertion on the posterior calcaneal tuberosity and compared it with 2 standard bone anchor techniques. A total of 40 fresh-frozen cadaver specimens were used to compare 3 fixation techniques for reinserting the Achilles tendon: single row anchors, double row anchors, and buttons. The ultimate loads and failure mechanisms were recorded. The button assembly (median load 764 N, range 713 to 888) yielded a median fixation strength equal to 202% (range 137% to 251%) of that obtained with the double row anchors (median load 412 N, range 301 to 571) and 255% (range 213% to 317%) of that obtained with the single row anchors (median load 338 N, range 241 to 433N). The most common failure mechanisms were suture breakage with the buttons (55%) and pull out of the implant with the double row (70%) and single row (85%) anchors. The results of the present biomechanical cadaver study have shown that Achilles tendon reinsertion fixation using the button technique provides superior pull out strength than the bone anchors tested. Copyright © 2014 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Fatigue of DIN 1.4914 martensitic stainless steel in a hydrogen environment

NASA Astrophysics Data System (ADS)

Shakib, J. I.; Ullmaier, H.; Little, E. A.; Faulkner, R. G.; Schmilz, W.; Chung, T. E.

1994-09-01

Fatigue tests at room temperature in vacuum, air and hydrogen have been carried out on specimens of DIN 1.4914 martensitic stainless steel in load-controlled, push-pull type experiments. Fatigue lifetimes in hydrogen are significantly lower than in both vacuum and air and the degradation is enhanced by lowering the test frequency or introducing hold times into the tension half-cycle. Fractographic examinations reveal hydrogen embrittlement effects in the form of internal cracking between fatigue striations together with surface modifications, particularly at low stress amplitudes. It is suggested that gaseous hydrogen can influence both fatigue crack initiation and propagation events in martensitic steels.

Flight test results for several light, canard-configured airplanes

NASA Technical Reports Server (NTRS)

Brown, Philip W.

1987-01-01

Brief flight evaluations of two different, light, composite constructed, canard and winglet configured airplanes were performed to assess their handling qualities; one airplane was a single engine, pusher design and the other a twin engine, push-pull configuration. An emphasis was placed on the slow speed/high angle of attack region for both airplanes and on the engine-out regime for the twin. Mission suitability assessment included cockpit and control layout, ground and airborne handling qualities, and turbulence response. Very limited performance data was taken. Stall/spin tests and the effects of laminar flow loss on performance and handling qualities were assessed on an extended range, single engine pusher design.

Multiple balance tests improve the assessment of postural stability in subjects with Parkinson's disease

PubMed Central

Jacobs, J V; Horak, F B; Tran, V K; Nutt, J G

2006-01-01

Objectives Clinicians often base the implementation of therapies on the presence of postural instability in subjects with Parkinson's disease (PD). These decisions are frequently based on the pull test from the Unified Parkinson's Disease Rating Scale (UPDRS). We sought to determine whether combining the pull test, the one‐leg stance test, the functional reach test, and UPDRS items 27–29 (arise from chair, posture, and gait) predicts balance confidence and falling better than any test alone. Methods The study included 67 subjects with PD. Subjects performed the one‐leg stance test, the functional reach test, and the UPDRS motor exam. Subjects also responded to the Activities‐specific Balance Confidence (ABC) scale and reported how many times they fell during the previous year. Regression models determined the combination of tests that optimally predicted mean ABC scores or categorised fall frequency. Results When all tests were included in a stepwise linear regression, only gait (UPDRS item 29), the pull test (UPDRS item 30), and the one‐leg stance test, in combination, represented significant predictor variables for mean ABC scores (r2 = 0.51). A multinomial logistic regression model including the one‐leg stance test and gait represented the model with the fewest significant predictor variables that correctly identified the most subjects as fallers or non‐fallers (85% of subjects were correctly identified). Conclusions Multiple balance tests (including the one‐leg stance test, and the gait and pull test items of the UPDRS) that assess different types of postural stress provide an optimal assessment of postural stability in subjects with PD. PMID:16484639

42 CFR 84.151 - Harness test; minimum requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... concrete floor without disarranging the harness or exerting a pull on the facepiece. (5) The arrangement... manner that prevents a pull equivalent to dragging the maximum length of the hose over a concrete floor...

Field demonstration of CO2 leakage detection and potential impacts on groundwater quality at Brackenridge Field Laboratory

NASA Astrophysics Data System (ADS)

Zou, Y.; Yang, C.; Guzman, N.; Delgado, J.; Mickler, P. J.; Horvoka, S.; Trevino, R.

2015-12-01

One concern related to GCS is possible risk of unintended CO2 leakage from the storage formations into overlying potable aquifers on underground sources of drinking water (USDW). Here we present a series of field tests conducted in an alluvial aquifer which is on a river terrace at The University of Texas Brackenridge Field Laboratory. Several shallow groundwater wells were completed to the limestone bedrock at a depth of 6 m and screened in the lower 3 m. Core sediments recovered from the shallow aquifer show that the sediments vary in grain size from clay-rich layers to coarse sandy gravels. Two main types of field tests were conducted at the BFL: single- (or double-) well push-pull test and pulse-like CO2 release test. A single- (or double-) well push-pull test includes three phases: the injection phase, the resting phase and pulling phase. During the injection phase, groundwater pumped from the shallow aquifer was stored in a tank, equilibrated with CO2 gasand then injected into the shallow aquifer to mimic CO2 leakage. During the resting phase, the groundwater charged with CO2 reacted with minerals in the aquifer sediments. During the pulling phase, groundwater was pumped from the injection well and groundwater samples were collected continuously for groundwater chemistry analysis. In such tests, large volume of groundwater which was charged with CO2 can be injected into the shallow aquifer and thus maximize contact of groundwater charged with CO2. Different than a single- (or double-) well push-pull test, a pulse-like CO2 release test for validating chemical sensors for CO2 leakage detection involves a CO2 release phase that CO2 gas was directly bubbled into the testing well and a post monitoring phase that groundwater chemistry was continuously monitored through sensors and/or grounder sampling. Results of the single- (or double-) well push-pull tests conducted in the shallow aquifer shows that the unintended CO2 leakage could lead to dissolution of carbonates and some silicates and mobilization of heavy metals from the aquifer sediments to groundwater, however, such mobilization posed no risks on groundwater quality at this site. The pulse-like tests have demonstrated it is plausible to use chemical sensors for CO2 leakage detection in groundwater.

Method and device for determining bond separation strength using induction heating

NASA Technical Reports Server (NTRS)

Coultrip, Robert H. (Inventor); Johnson, Samuel D. (Inventor); Copeland, Carl E. (Inventor); Phillips, W. Morris (Inventor); Fox, Robert L. (Inventor)

1994-01-01

An induction heating device includes an induction heating gun which includes a housing, a U-shaped pole piece having two spaced apart opposite ends defining a gap there between, the U-shaped pole piece being mounted in one end of the housing, and a tank circuit including an induction coil wrapped around the pole piece and a capacitor connected to the induction coil. A power source is connected to the tank circuit. A pull test machine is provided having a stationary chuck and a movable chuck, the two chucks holding two test pieces bonded together at a bond region. The heating gun is mounted on the pull test machine in close proximity to the bond region of the two test pieces, whereby when the tank circuit is energized, the two test pieces are heated by induction heating while a tension load is applied to the two test pieces by the pull test machine to determine separation strength of the bond region.

Raman measurements of Kevlar-29 fiber pull-out test at different strain levels

NASA Astrophysics Data System (ADS)

Wang, Quan; Lei, Zhenkun; Kang, Yilan; Qiu, Wei

2008-11-01

This paper adopted Kevlar-29 fiber monofilament embedding technology to prepare fiber/ epoxy resin tensile specimen. The specimen was pulled on a homemade and portable mini-loading device. At the same time micro-Raman spectroscopy is introduced to detect the distributions of stress on the embedded fiber at different strain levels. The characteristic peak shift of the 1610 cm-1 in Raman band has a linear relationship with the strain or stress. The experimental results show that the fiber axial stress decreases gradually from the embedded fiber-start to the embedded fiber-end at the same strain level. At different strain levels, the fiber axial stress increases along with the applied load. It reveals that there is a larger fiber axial stress distribution under a larger strain level. And the stress transfer is realized gradually from the embedded fiber-start to the fiber-end. Stress concentration exists in the embedded fiber-end, which is a dangerous region for interfacial debonding easily.

The decline of cooperation, the rise of competition: developmental effects of long-term social change in Mexico.

PubMed

García, Camilo; Rivera, Natanael; Greenfield, Patricia M

2015-02-01

Using Greenfield's theory of sociocultural change and human development as a point of departure, we carried out two experimental studies exploring the implications of decades of globalised social change in Mexico for children's development of cooperation and competition. In rural San Vicente, Baja California, the baseline was 1970 and the historical comparison took place 40 years later. In Veracruz, the baseline was 1985 and the historical comparison took place 20 years later. In Veracruz, children were tested in both rural and urban settings. We hypothesized that cooperative behavior would decrease in all three settings as a result of the sociocultural transformations of the past decades in Mexico. The Madsen Marble Pull Game was used to assess cooperative and competitive behavior. As predicted by Greenfield's theory of social change and human development, the Marble Pull procedure revealed a striking decrease over time in levels of cooperative behavior, with a corresponding rise in competitive behavior, in all three settings. © 2015 International Union of Psychological Science.

Use of steel fibres recovered from waste tyres as reinforcement in concrete: pull-out behaviour, compressive and flexural strength.

PubMed

Aiello, M A; Leuzzi, F; Centonze, G; Maffezzoli, A

2009-06-01

The increasing amount of waste tyres worldwide makes the disposition of tyres a relevant problem to be solved. In the last years over three million tons of waste tyres were generated in the EU states [ETRA, 2006. Tyre Technology International - Trends in Tyre Recycling. http://www.etra-eu.org]; most of them were disposed into landfills. Since the European Union Landfill Directive (EU Landfill, 1999) aims to significantly reduce the landfill disposal of waste tyres, the development of new markets for the tyres becomes fundamental. Recently some research has been devoted to the use of granulated rubber and steel fibres recovered from waste tyres in concrete. In particular, the concrete obtained by adding recycled steel fibres evidenced a satisfactory improvement of the fragile matrix, mostly in terms of toughness and post-cracking behaviour. As a consequence RSFRC (recycled steel fibres reinforced concrete) appears a promising candidate for both structural and non-structural applications. Within this context a research project was undertaken at the University of Salento (Italy) aiming to investigate the mechanical behaviour of concrete reinforced with RSF (recycled steel fibres) recovered from waste tyres by a mechanical process. In the present paper results obtained by the experimental work performed up to now are reported. In order to evaluate the concrete-fibres bond characteristics and to determine the critical fibre length, pull-out tests were initially carried out. Furthermore compressive strength of concrete was evaluated for different volume ratios of added RSF and flexural tests were performed to analyze the post-cracking behaviour of RSFRC. For comparison purposes, samples reinforced with industrial steel fibres (ISF) were also considered. Satisfactory results were obtained regarding the bond between recycled steel fibres and concrete; on the other hand compressive strength of concrete seems unaffected by the presence of fibres despite their irregular geometric properties. Finally, flexural tests furnished in some cases results comparable to those obtained when using ISF as concerns the post-cracking behaviour.

Fragile Victory

DTIC Science & Technology

1994-02-08

units, in addition to the armored and mechanized divisions north of Kuwait City, comprised the VIII Tank Corps. The goalies , located on the northern... pull the Saudi fat out of an August fire. Utilizing the opposed mechanized movement rates established by the Army’s CACDA Jiffy III War Game, Volume...against an enemy who frequently was unwilling "to pull the trigger". Our national will, untested due to the quick, bloodless nature of the war, probably

Split marketing as a risk factor for Salmonella enterica infection in swine.

PubMed

Rostagno, Marcos H; Hurd, H Scott; McKean, James D

2009-09-01

On-farm reduction of Salmonella carriage prevalence in pigs requires the identification of risk factors to direct interventions development. This study was designed to determine if split marketing of finishing pigs constitutes a risk factor for Salmonella infections, by comparing Salmonella prevalence in the first group of pigs selected for harvest ("first pull") versus the prevalence in the last group of pigs selected for harvest ("close out") from multiple commercial finishing lots. Nine paired samplings were conducted consisting in matched groups of pigs from individual barns as the first pull and the close out with a 4-week interval between groups. From each group, fecal and meat samples were collected, on-farm and at harvest, respectively. Fecal samples were selectively enriched, and analyzed for the presence of Salmonella, whereas meat juice samples were analyzed for the presence of antibodies against Salmonella. In 7/9 (77.8%) of the studied barns, an increase in Salmonella prevalence was observed, based on both bacteriologic and serologic analysis. Overall, there was an increase of 9.2% (p < 0.05) in bacteriologic prevalence, and 31.3% (p < 0.05) in serologic prevalence from first pull to close out groups. This study demonstrates that a significant increase in Salmonella prevalence occurs between the first and the last group of pigs harvested from finishing lots, with close out groups of market pigs posing a higher risk for Salmonella contaminations.

Upper body push and pull strength ratio in recreationally active adults.

PubMed

Negrete, Rodney J; Hanney, William J; Pabian, Patrick; Kolber, Morey J

2013-04-01

Agonist to antagonist strength data is commonly analyzed due to its association with injury and performance. The purpose of this study was to examine the agonist to antagonist ratio of upper body strength using two simple field tests (timed push up/timed modified pull up) in recreationally active adults and to establish the basis for reference standards. One hundred eighty (180) healthy recreationally active adults (111 females and 69 males, aged 18-45 years) performed two tests of upper body strength in random order: 1. Push-ups completed during 3 sets of 15 seconds with a 45 second rest period between each set and 2. Modified pull-ups completed during 3 sets of 15 seconds with a 45 second rest period between each set. The push-up to modified pull-up ratio for the males was 1.57:1, whereas females demonstrated a ratio of 2.72:1. The results suggest that for our group of healthy recreationally active subjects, the upper body "pushing" musculature is approximately 1.5-2.7 times stronger than the musculature involved for pulling. In this study, these recreationally active adults displayed greater strength during the timed push-ups than the modified pull-ups. The relationship of these imbalances to one's performance and or injury risk requires further investigation. The reference values, however, may serve the basis for future comparison and prospective investigations. The field tests in this study can be easily implemented by clinicians and an agonist/antagonist ratio can be determined and compared to our findings. 2b.

Combat Fitness a Concept Vital to National Defense

DTIC Science & Technology

2010-06-18

Physical fitness testing has traditionally been focused on a 1.5- to 3-mile run, push-ups, sit-ups, and, in some Services pull -ups, flexibility, and...Performance 6 Shoot Physical Requirements Employ hand grenades Run under load, jump, bound, high/low crawl, climb, push, pull , squat, lunge, roll...jump, bound, high/low crawl, climb, push, pull , squat, lunge, roll, stop, start, change direction and get up/down. Navigate from one point to

Posterior repair with perforated porcine dermal graft.

PubMed

Taylor, G Bernard; Moore, Robert D; Miklos, John R; Mattox, T Fleming

2008-01-01

To compare postoperative vaginal incision separation and healing in patients undergoing posterior repair with perforated porcine dermal grafts with those that received grafts without perforations. Secondarily, the tensile properties of the perforated and non-perforated grafts were measured and compared. This was a non-randomized retrospective cohort analysis of women with stage II or greater rectoceles who underwent posterior repair with perforated and non-perforated porcine dermal grafts (Pelvicol(TM) CR Bard Covington, GA USA). The incidence of postoperative vaginal incision separation (dehiscence) was compared. A secondary analysis to assess graft tensile strength, suture pull out strength, and flexibility after perforation was performed using standard test method TM 0133 and ASTM bending and resistance protocols. Seventeen percent of patients (21/127) who received grafts without perforations developed vaginal incision dehiscence compared to 7% (5/71) of patients who received perforated grafts (p = 0.078). Four patients with vaginal incision dehiscence with non-perforated grafts required surgical revision to facilitate healing. Neither tensile strength or suture pull out strength were significantly different between perforated and non-perforated grafts (p = 0.81, p = 0.29, respectively). There was no difference in the flexibility of the two grafts (p = 0.20). Perforated porcine dermal grafts retain their tensile properties and are associated with fewer vaginal incision dehiscences.

Effect of Strain Rates and Pre-Twist on Tensile Strength of Kevlar KM2 Single Fiber

DTIC Science & Technology

2013-04-01

cardboard tabs at a standard gage length of 5.2 mm for testing using 3M DP8005 epoxy . The cardboard tabs were glued to stainless steel setscrews so that...did not pull out of the glue . If pullout were evident, the force would rise followed by a flat portion where the fiber takes a small amount of load...until the fiber comes back into contact with the glue followed by another rise and so on until failure. Figure 5. Raw data from a high-rate

Tree stability under wind: simulating uprooting with root breakage using a finite element method.

PubMed

Yang, Ming; Défossez, Pauline; Danjon, Frédéric; Fourcaud, Thierry

2014-09-01

Windstorms are the major natural hazard affecting European forests, causing tree damage and timber losses. Modelling tree anchorage mechanisms has progressed with advances in plant architectural modelling, but it is still limited in terms of estimation of anchorage strength. This paper aims to provide a new model for root anchorage, including the successive breakage of roots during uprooting. The model was based on the finite element method. The breakage of individual roots was taken into account using a failure law derived from previous work carried out on fibre metal laminates. Soil mechanical plasticity was considered using the Mohr-Coulomb failure criterion. The mechanical model for roots was implemented in the numerical code ABAQUS using beam elements embedded in a soil block meshed with 3-D solid elements. The model was tested by simulating tree-pulling experiments previously carried out on a tree of Pinus pinaster (maritime pine). Soil mechanical parameters were obtained from laboratory tests. Root system architecture was digitized and imported into ABAQUS while root material properties were estimated from the literature. Numerical simulations of tree-pulling tests exhibited realistic successive root breakages during uprooting, which could be seen in the resulting response curves. Broken roots could be visually located within the root system at any stage of the simulations. The model allowed estimation of anchorage strength in terms of the critical turning moment and accumulated energy, which were in good agreement with in situ measurements. This study provides the first model of tree anchorage strength for P. pinaster derived from the mechanical strength of individual roots. The generic nature of the model permits its further application to other tree species and soil conditions.

Tree stability under wind: simulating uprooting with root breakage using a finite element method

PubMed Central

Yang, Ming; Défossez, Pauline; Danjon, Frédéric; Fourcaud, Thierry

2014-01-01

Background and Aims Windstorms are the major natural hazard affecting European forests, causing tree damage and timber losses. Modelling tree anchorage mechanisms has progressed with advances in plant architectural modelling, but it is still limited in terms of estimation of anchorage strength. This paper aims to provide a new model for root anchorage, including the successive breakage of roots during uprooting. Methods The model was based on the finite element method. The breakage of individual roots was taken into account using a failure law derived from previous work carried out on fibre metal laminates. Soil mechanical plasticity was considered using the Mohr–Coulomb failure criterion. The mechanical model for roots was implemented in the numerical code ABAQUS using beam elements embedded in a soil block meshed with 3-D solid elements. The model was tested by simulating tree-pulling experiments previously carried out on a tree of Pinus pinaster (maritime pine). Soil mechanical parameters were obtained from laboratory tests. Root system architecture was digitized and imported into ABAQUS while root material properties were estimated from the literature. Key Results Numerical simulations of tree-pulling tests exhibited realistic successive root breakages during uprooting, which could be seen in the resulting response curves. Broken roots could be visually located within the root system at any stage of the simulations. The model allowed estimation of anchorage strength in terms of the critical turning moment and accumulated energy, which were in good agreement with in situ measurements. Conclusions This study provides the first model of tree anchorage strength for P. pinaster derived from the mechanical strength of individual roots. The generic nature of the model permits its further application to other tree species and soil conditions. PMID:25006178

Wire Crimp Connectors Verification using Ultrasonic Inspection

NASA Technical Reports Server (NTRS)

Cramer, K. Elliott; Perey, Daniel F.; Yost, William T.

2007-01-01

The development of a new ultrasonic measurement technique to quantitatively assess wire crimp connections is discussed. The amplitude change of a compressional ultrasonic wave propagating through the junction of a crimp connector and wire is shown to correlate with the results of a destructive pull test, which previously has been used to assess crimp wire junction quality. Various crimp junction pathologies (missing wire strands, incorrect wire gauge, incomplete wire insertion in connector) are ultrasonically tested, and their results are correlated with pull tests. Results show that the ultrasonic measurement technique consistently (as evidenced with pull-testing data) predicts good crimps when ultrasonic transmission is above a certain threshold amplitude level. A physics-based model, solved by finite element analysis, describes the compressional ultrasonic wave propagation through the junction during the crimping process. This model is in agreement within 6% of the ultrasonic measurements. A prototype instrument for applying the technique while wire crimps are installed is also presented.

The Improved Biological Performance of a Novel Low Elastic Modulus Implant

PubMed Central

Lei, Wei; Wang, Zhen; Li, Jing; Fan, Xiangli; Li, Xiaokang; Li, Shujun; Guo, Zheng

2013-01-01

Background The mismatch of the elastic modulus between implants and bone tissue can lead to stress shielding, bone resorption and poor osseointegration. Compared with normal bone tissue, this problem is much more serious in osteoporosis. The purpose of this study was designed to find out whether the novel Ti-24Nb-4Zr-7.9Sn (TNZS) implant with low elastic modulus and high strength was suitable for biomedical material, especially in osteoporosis. Methodology In vitro study, the viability and Alkaline phosphatase (ALP) activity of osteoblasts on the TNZS and Ti-6V-4V (TAV) were observed. In vivo study, 30 adult female New Zealand rabbits were selected and divided randomly into two groups: sham-operation (SHAM, n = 6) and ovariectomised in combination with methylprednisolone treatment (OVX+MP, n = 24). Two implants were then placed in the tibia of each OVX + MP group rabbit, one in each side (left: TAV; right: TNZS). The OVX + MP group rabbits were sacrificed at 4 and 12 weeks after the implantation. The osteoporotic bone responses to the TNZS and TAV implants were evaluated by pull-out test, Micro-CT analyses and histological observation. Principal Findings Compared with the TAV group, the TNZS group showed a significant increase (P<0.05) in cell viability and ALP activity, new bone formation and pull-out force. Conclusions The novel TNZS implants show good biological performance both in vitro and in vivo, which suggests that the alloys are suitable for biomedical applications, especially in osteoporosis. PMID:23437048

Antenna Deployment for a Pathfinder Lunar Radio Observatory

NASA Astrophysics Data System (ADS)

MacDowall, Robert J.; Minetto, F. A.; Lazio, T. W.; Jones, D. L.; Kasper, J. C.; Burns, J. O.; Stewart, K. P.; Weiler, K. W.

2012-05-01

A first step in the development of a large radio observatory on the moon for cosmological or other astrophysical and planetary goals is to deploy a few antennas as a pathfinder mission. In this presentation, we describe a mechanism being developed to deploy such antennas from a small craft, such as a Google Lunar X-prize lander. The antenna concept is to deposit antennas and leads on a polyimide film, such as Kapton, and to unroll the film on the lunar surface. The deployment technique utilized is to launch an anchor which pulls a double line from a reel at the spacecraft. Subsequently, the anchor is set by catching on the surface or collecting sufficient regolith. A motor then pulls in one end of the line, pulling the film off of its roller onto the lunar surface. Detection of a low frequency cutoff of the galactic radio background or of solar radio bursts by such a system would determine the maximum lunar ionospheric density at the time of measurement. The current design and testing, including videos of the deployment, will be presented. These activities are funded in part by the NASA Lunar Science Institute as an activity of the Lunar University Network for Astrophysical Research (LUNAR) consortium. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Antenna Deployment for a Pathfinder Lunar Radio Observatory

NASA Technical Reports Server (NTRS)

MacDowall, Robert J.; Minetto, F. A.; Lazio, T. W.; Jones, D. L.; Kasper, J. C.; Burns, J. O.; Stewart, K. P.; Weiler, K. W.

2012-01-01

A first step in the development of a large radio observatory on the moon for cosmological or other astrophysical and planetary goals is to deploy a few antennas as a pathfinder mission. In this presentation, we describe a mechanism being developed to deploy such antennas from a small craft, such as a Google Lunar X-prize lander. The antenna concept is to deposit antennas and leads on a polyimide film, such as Kapton, and to unroll the film on the lunar surface. The deployment technique utilized is to launch an anchor which pulls a double line from a reel at the spacecraft. Subsequently, the anchor is set by catching on the surface or collecting sufficient regolith. A motor then pulls in one end of the line, pulling the film off of its roller onto the lunar surface. Detection of a low frequency cutoff of the galactic radio background or of solar radio bursts by such a system would determine the maximum lunar ionospheric density at the time of measurement. The current design and testing, including videos of the deployment, will be presented. These activities are funded in part by the NASA Lunar Science Institute as an activity of the Lunar University Network for Astrophysical Research (LUNAR) consortium. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Factors affecting minimum push and pull forces of manual carts.

PubMed

Al-Eisawi, K W; Kerk, C J; Congleton, J J; Amendola, A A; Jenkins, O C; Gaines, W

1999-06-01

The minimum forces needed to manually push or pull a 4-wheel cart of differing weights with similar wheel sizes from a stationary state were measured on four floor materials under different conditions of wheel width, diameter, and orientation. Cart load was increased from 0 to 181.4 kg in increments of 36.3 kg. The floor materials were smooth concrete, tile, asphalt, and industrial carpet. Two wheel widths were tested: 25 and 38 mm. Wheel diameters were 51, 102, and 153 mm. Wheel orientation was tested at four levels: F0R0 (all four wheels aligned in the forward direction), F0R90 (the two front wheels, the wheels furthest from the cart handle, aligned in the forward direction and the two rear wheels, the wheels closest to the cart handle, aligned at 90 degrees to the forward direction), F90R0 (the two front wheels aligned at 90 degrees to the forward direction and the two rear wheels aligned in the forward direction), and F90R90 (all four wheels aligned at 90 degrees to the forward direction). Wheel width did not have a significant effect on the minimum push/pull forces. The minimum push/pull forces were linearly proportional to cart weight, and inversely proportional to wheel diameter. The coefficients of rolling friction were estimated as 2.2, 2.4, 3.3, and 4.5 mm for hard rubber wheels rolling on smooth concrete, tile, asphalt, and industrial carpet floors, respectively. The effect of wheel orientation was not consistent over the tested conditions, but, in general, the smallest minimum push/pull forces were measured with all four wheels aligned in the forward direction, whereas the largest minimum push/pull forces were measured when all four wheels were aligned at 90 degrees to the forward direction. There was no significant difference between the push and pull forces when all four wheels were aligned in the forward direction.

Airpower’s Role in Homeland Defense: A Western Hemisphere Perspective

DTIC Science & Technology

2002-06-01

remain concerning airpower’s contribution to homeland defense. This thesis is neither about how to tactically solve the goalie CAP gameplan over the...Francisco to solve liaison issues between AAF units and the Navy. Aircraft were rushed to the West Coast as Lend-Lease planes were pulled off East...detect and interrogate aircraft over land out to 200 NM with a nine-hour endurance. These are usually based at Curacao, but have been pulled back since

Green Flight Challenge

NASA Image and Video Library

2011-09-27

The e-Genius aircraft is pulled pulled out to the runway for the miles per gallon (MPG) flight during the 2011 Green Flight Challenge, sponsored by Google, at the Charles M. Schulz Sonoma County Airport in Santa Rosa, Calif. on Tuesday, Sept. 27, 2011. NASA and the Comparative Aircraft Flight Efficiency (CAFE) Foundation are having the challenge with the goal to advance technologies in fuel efficiency and reduced emissions with cleaner renewable fuels and electric aircraft. Photo Credit: (NASA/Bill Ingalls)

Mineral-Based Coating of Plasma-Treated Carbon Fibre Rovings for Carbon Concrete Composites with Enhanced Mechanical Performance.

PubMed

Schneider, Kai; Lieboldt, Matthias; Liebscher, Marco; Fröhlich, Maik; Hempel, Simone; Butler, Marko; Schröfl, Christof; Mechtcherine, Viktor

2017-03-29

Surfaces of carbon fibre roving were modified by means of a low temperature plasma treatment to improve their bonding with mineral fines; the latter serving as an inorganic fibre coating for the improved mechanical performance of carbon reinforcement in concrete matrices. Variation of the plasma conditions, such as gas composition and treatment time, was accomplished to establish polar groups on the carbon fibres prior to contact with the suspension of mineral particles in water. Subsequently, the rovings were implemented in a fine concrete matrix and their pull-out performance was assessed. Every plasma treatment resulted in increased pull-out forces in comparison to the reference samples without plasma treatment, indicating a better bonding between the mineral coating material and the carbon fibres. Significant differences were found, depending on gas composition and treatment time. Microscopic investigations showed that the samples with the highest pull-out force exhibited carbon fibre surfaces with the largest areas of hydration products grown on them. Additionally, the coating material ingresses into the multifilament roving in these specimens, leading to better force transfer between individual carbon filaments and between the entire roving and surrounding matrix, thus explaining the superior mechanical performance of the specimens containing appropriately plasma-treated carbon roving.

Mineral-Based Coating of Plasma-Treated Carbon Fibre Rovings for Carbon Concrete Composites with Enhanced Mechanical Performance

PubMed Central

Schneider, Kai; Lieboldt, Matthias; Liebscher, Marco; Fröhlich, Maik; Hempel, Simone; Butler, Marko; Schröfl, Christof; Mechtcherine, Viktor

2017-01-01

Surfaces of carbon fibre roving were modified by means of a low temperature plasma treatment to improve their bonding with mineral fines; the latter serving as an inorganic fibre coating for the improved mechanical performance of carbon reinforcement in concrete matrices. Variation of the plasma conditions, such as gas composition and treatment time, was accomplished to establish polar groups on the carbon fibres prior to contact with the suspension of mineral particles in water. Subsequently, the rovings were implemented in a fine concrete matrix and their pull-out performance was assessed. Every plasma treatment resulted in increased pull-out forces in comparison to the reference samples without plasma treatment, indicating a better bonding between the mineral coating material and the carbon fibres. Significant differences were found, depending on gas composition and treatment time. Microscopic investigations showed that the samples with the highest pull-out force exhibited carbon fibre surfaces with the largest areas of hydration products grown on them. Additionally, the coating material ingresses into the multifilament roving in these specimens, leading to better force transfer between individual carbon filaments and between the entire roving and surrounding matrix, thus explaining the superior mechanical performance of the specimens containing appropriately plasma-treated carbon roving. PMID:28772719

Are pushing and pulling work-related risk factors for upper extremity symptoms? A systematic review of observational studies.

PubMed

Hoozemans, M J M; Knelange, E B; Frings-Dresen, M H W; Veeger, H E J; Kuijer, P P F M

2014-11-01

Systematically review observational studies concerning the question whether workers that perform pushing/pulling activities have an increased risk for upper extremity symptoms as compared to workers that perform no pushing/pulling activities. A search in MEDLINE via PubMed and EMBASE was performed with work-related search terms combined with push/pushing/pull/pulling. Studies had to examine exposure to pushing/pulling in relation to upper extremity symptoms. Two authors performed the literature selection and assessment of the risk of bias in the studies independently. A best evidence synthesis was used to draw conclusions in terms of strong, moderate or conflicting/insufficient evidence. The search resulted in 4764 studies. Seven studies were included, with three of them of low risk of bias, in total including 8279 participants. A positive significant relationship with upper extremity symptoms was observed in all four prospective cohort studies with effect sizes varying between 1.5 and 4.9. Two out of the three remaining studies also reported a positive association with upper extremity symptoms. In addition, significant positive associations with neck/shoulder symptoms were found in two prospective cohort studies with effect sizes of 1.5 and 1.6, and with shoulder symptoms in one of two cross-sectional studies with an effect size of 2.1. There is strong evidence that pushing/pulling is related to upper extremity symptoms, specifically for shoulder symptoms. There is insufficient or conflicting evidence that pushing/pulling is related to (combinations of) upper arm, elbow, forearm, wrist or hand symptoms. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Surgical management of recto-sigmoid Hirschsprung's disease.

PubMed

Nouira, F; Ben Ahmed, Y; Sarrai, N; Ghorbel, S; Jlidi, S; Khemakhem, R; Charieg, A; Chaouachi, B

2012-01-01

Over the years, the surgical management of recto-sigmoid Hirschsprung's disease (HD) has evolved radically and at present a single stage transanal pull-through can be done in suitable cases, which obviates the need for multiple surgeries. The aim of this paper was to evaluate the role of transanal pull-through in the management of recto-sigmoid HD in our institution. A retrospective analysis (between January 2003 and December 2009) was carried out on all cases of Hirschsprung's reporting to unity of pediatric surgery of Tunis Children's Hospital that were managed by transanal pull-through as a definitive treatment. All selected patients including neonates had an aganglionic segment confined to the rectosigmoid area, confirmed by preoperative barium enema and postoperative histology. Twenty-six children (86%) had their operation done without construction of prior colostomy. Transanal pull-through was performed in 31 children. Mean operating time was 150 minutes (range 64 to 300 minutes). No patients required laparotomy because all patients including neonates had an aganglionic segment confined to the rectosigmoid area. Blood loss ranged between 20 to 56 ml without blood replacement. Since all children were given an epidural caudal block, the requirement of analgesia in these cases was minimal. Postoperative complications included perianal excoriation in 7 out of 31 patients lasting from 3 weeks to 6 months. Complete anorectal continence was noted in 21 of 31 (67%) children in follow up of 3-5 years. Transanal endorectal pull-through procedure for the management of rectosigmoid HD is now a well-established and preferred approach. Parental satisfaction is immense due to the lack of scars on the abdomen. As regards the continence, a long-term follow-up is necessary to appreciate better the functional results of this surgery.

Children's and women's ability to fire handguns. The Pediatric Practice Research Group.

PubMed

Naureckas, S M; Galanter, C; Naureckas, E T; Donovan, M; Christoffel, K K

1995-12-01

To evaluate whether strength differences between children and women might keep children from firing handguns and to determine how many young children can fire available handguns. One- and two-index finger trigger-pull strength was tested using a standard protocol. Data on trigger-pull settings of 64 commercially available handguns were obtained. Convenience sample of well children and their mothers at four Chicago (Ill)-area pediatric practices for health supervision visits, and of siblings of emergency department patients, during an 8-week period. None. One- and two-index finger trigger-pull strength of mothers and children. Twenty-five percent of 3- to 4-year-olds, 70% of 5- to 6-year-olds, and 90% of 7- to 8-year-olds have a two-finger trigger-pull strength of at least 10 lb, the fifth percentile one-finger trigger-pull strength of adult women. Forty (62.5%) of 64 handguns require trigger-pull strength of less than 5 lb; 19 (30%) of 64 require 5 to 10 lb. Significant overlap exists in the trigger-pull strength of young children and women, limiting the potential use of increased trigger-pull settings to discourage firearm discharge by children. Young children are strong enough to fire many handguns now in circulation.

Role of heterogeneous research and development funds in the productivity of the US manufacturing industry

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

Rhee, C.O.

1987-01-01

This paper investigates, in the framework of firm's optimal behavior, the effect of company-funded and federally-funded RandD on productivity in selected US industries. Especially, the role of federal funding RandD in productivity through direct as well as indirect mechanisms is analyzed. Using different model specification, two types of RandD-federal and company, and data of industry level, no support can be found for the blanket statement that federally-funded RandD (FRD) crowds out or pulls in company-funding RandD in productivity growth. Whether crowding-out or pulling-in is shown to be industry-specific as well as based on FRD's time dimension. Hence, the lag effectmore » of heterogeneous RandD funds on productivity is emphasized. The classification of heterogeneous RandD funds into basic research, applied research, and development is adopted to look at the impact of each on productivity. The model of firm's optimal behavior following such classification demonstrates that federally-funded basic research has a tremendous pulling-in impact on company-funded applied research and development, respectively.« less

[Observation on the clinical application effects of skin distractor on the treatment of scars].

PubMed

Gui, W L; Yang, E; Zhang, H S

2017-03-20

Objective: To explore clinical application effects of skin distractor on the treatment of scars and to observe effects of skin distractor with different pull speeds on different parts scars of human body. Methods: One hundred and four patients with scars, conforming to the study criteria, were hospitalized in our unit from January 2014 to June 2015. Patients were divided into 2 mm/d group and 4 mm/d group according to the random number table, with 52 patients in each group. After admission, skin distractors were pasted on scars in face and neck, trunk, and extremities of patients in 2 groups, with inner edges of pasteboards close to outside edges of longer sides of scars. Skin distractors in 2 mm/d group and 4 mm/d group were pulled to scars axis direction as speeds of 2 mm/d and 4 mm/d, respectively. Pull time equals values of pull speeds divided by width of scars. Scars were resected after finishing pulling. Immediately after scars resection, skin distractors were pasted again with inner edges of pasteboards close to outside edges of longer sides of incision and removed when stitches were taken out. Scars of patients were scored by Vancouver Scar Scale (VSS), and Patient and Observer Scar Assessment Scale (POSAS) was used to record scores of patient scar assessment scale (PSAS), observer scar assessment scale (OSAS) and overall scores of patients and observers of scars of patients before and one year after scars resection. Data were processed with χ (2) test, independent samples t test, paired samples t test, independent samples non-parametric rank-sum test and paired samples non-parametric rank-sum test. Results: (1) Scores of all scars of patients in 2 groups before scars resection were close (with t values from -1.384 to 0.622, P values above 0.05), obviously higher than those of one year post scars resection (with t values from 11.085 to 24.835, P values below 0.01). Scores of scars in face and neck, trunk and extremities in 2 groups before scars resection were close (with Z values from -1.651 to -0.035, t values from -1.549 to 0.219, P values above 0.05), significantly higher than those of one year post scar resection (with Z values from -2.992 to -2.555, t values from 8.739 to 19.076, P values below 0.01). (2) Scores of all scars of patients in 2 mm/d group of one year post scars resection were lower than those in 4 mm/d group (with t values from -2.583 to -2.018, P values below 0.05). PSAS scores of scars in face and neck and trunk in 2 mm/d group of one year post scars resection were lower than those in 4 mm/d group (with Z values respectively -2.385 and -2.198, P values below 0.05), other scores of scars in face and neck and trunk of patients in 2 groups of one year post scars resection were close (with Z values from -1.841 to -0.363, P values above 0.05). VSS scores, PSAS scores, OSAS scores, patients' overall scores, and observers' overall scores in 2 mm/d groups were (4.6±0.8), (28±4), (28±4), (4.7±0.7), (4.8±1.4) points, respectively, lower than those in 4 mm/d group[(5.2±0.8), (32±4), (31±6), (5.5±1.2), (5.5±1.0) points, respectively, with t values from -3.712 to -2.105, P <0.05 or P <0.01]. Conclusions: Skin distractor has better effects on the treatment of scars, and treatment effects of skin distractor in extremities pulled by 2 mm/d are better than those pulled by 4 mm/d.

Posterior Meniscal Root Repairs: Outcomes of an Anatomic Transtibial Pull-Out Technique.

PubMed

LaPrade, Robert F; Matheny, Lauren M; Moulton, Samuel G; James, Evan W; Dean, Chase S

2017-03-01

Outcomes after transtibial pull-out repair for posterior meniscal root tears remain underreported, and factors that may affect outcomes are unknown. Purpose/Hypothesis: The purpose of this study was to compare patient-centered outcomes after transtibial pull-out repair for posterior root tears in patients <50 and ≥50 years of age. We hypothesized that improvement in function and activity level at minimum 2-year follow-up would be similar among patients <50 years of age compared with patients ≥50 years and among patients undergoing medial versus lateral root repairs. Cohort study; Level of evidence, 3. Inclusion criteria were patients aged 18 years or older who underwent anatomic transtibial pull-out repair of the medial or lateral posterior meniscus root by a single surgeon. All patients were identified from a data registry consisting of prospectively collected data in a consecutive series. Cohorts were analyzed by age (<50 years [n = 35] vs ≥50 years [n = 15]) and laterality (lateral [n = 15] vs medial [n = 35]). Patients completed a subjective questionnaire preoperatively and at minimum of 2 years postoperatively (Lysholm, Tegner, Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], 12-Item Short Form Health Survey [SF-12], and patient satisfaction with outcome). Failure was defined as revision meniscal root repair or partial meniscectomy. The analysis included 50 knees in 49 patients (16 females, 33 males; mean age, 38.3 years; mean body mass index, 26.6). Of the 50 knees, 45 were available for analysis. Three of 45 (6.7%) required revision surgery. All failures were in patients <50 years old, and all failures underwent medial root repair. No significant difference in failure was found based on age ( P=.541) or laterality ( P = .544). For age cohorts, Lysholm and WOMAC scores demonstrated significant postoperative improvement. For laterality cohorts, all functional scores significantly improved postoperatively. No significant difference was noted in postoperative Lysholm, WOMAC, SF-12, Tegner, or patient satisfaction scores for the age cohort or the laterality cohort. Outcomes after posterior meniscal root repair significantly improved postoperatively and patient satisfaction was high, regardless of age or meniscal laterality. Patients <50 years had outcomes similar to those of patients ≥50 years, as did patients who underwent medial versus lateral root repair. Transtibial double-tunnel pull-out meniscal root repair provided improvement in function, pain, and activity level, which may aid in delayed progression of knee osteoarthritis.

Comparison of a novel fixation device with standard suturing methods for spinal cord stimulators.

PubMed

Bowman, Richard G; Caraway, David; Bentley, Ishmael

2013-01-01

Spinal cord stimulation is a well-established treatment for chronic neuropathic pain of the trunk or limbs. Currently, the standard method of fixation is to affix the leads of the neuromodulation device to soft tissue, fascia or ligament, through the use of manually tying general suture. A novel semiautomated device is proposed that may be advantageous to the current standard. Comparison testing in an excised caprine spine and simulated bench top model was performed. Three tests were performed: 1) perpendicular pull from fascia of caprine spine; 2) axial pull from fascia of caprine spine; and 3) axial pull from Mylar film. Six samples of each configuration were tested for each scenario. Standard 2-0 Ethibond was compared with a novel semiautomated device (Anulex fiXate). Upon completion of testing statistical analysis was performed for each scenario. For perpendicular pull in the caprine spine, the failure load for standard suture was 8.95 lbs with a standard deviation of 1.39 whereas for fiXate the load was 15.93 lbs with a standard deviation of 2.09. For axial pull in the caprine spine, the failure load for standard suture was 6.79 lbs with a standard deviation of 1.55 whereas for fiXate the load was 12.31 lbs with a standard deviation of 4.26. For axial pull in Mylar film, the failure load for standard suture was 10.87 lbs with a standard deviation of 1.56 whereas for fiXate the load was 19.54 lbs with a standard deviation of 2.24. These data suggest a novel semiautomated device offers a method of fixation that may be utilized in lieu of standard suturing methods as a means of securing neuromodulation devices. Data suggest the novel semiautomated device in fact may provide a more secure fixation than standard suturing methods. © 2012 International Neuromodulation Society.

Enhancement of holding strength of cannulated screw supported with PMMA: a biomechanical study on femoral head [corrected].

PubMed

Zeynalov, Reşad; Ağır, İsmail; Akgülle, Ahmet Hamdi; Kocaoğlu, Barış; Yalçın, Mithat Selim

2015-07-01

The aim of this study was to evaluate the holding strength of cannulated screw with multiple holes on threaded area, supported with PMMA in femoral head. A total of 48 human femoral heads were divided into two groups after mineral density measurement with Q-CT. Seven-millimeter cannulated screws with multiple holes on threaded area supported with PMMA were used in the study group, while in the control group standard 7-mm cannulated screws were used. Each group was divided into three subgroups with eight femoral heads. Mineral density of each subgroup was equal to the other. Groups were compared in terms of pull-out, maximum extraction torque and cut-out. In pull-out group, maximum holding strength (N) was measured, while axial pull-out of 0.5 mm/sec applied with Instron. Results showed meaningful significant difference (p < 0.011) between two groups. In cut-out group, femoral heads were placed into Instron and loading was started from 5 N at 2 mm per minute at first, and it was continued until a failure, at least 5 mm, of implant was observed. Results showed significant difference (p < 0.05) between two groups. In maximum extraction group, 4° per second reverse torque (Nm) was applied with torque meter. Highest torque value was measured during extraction time, and results showed very significant difference (p < 0. 001) between two groups. The results of our new design of cannulated screw augmented with PMMA provided background data to clinical application.

Pull out strength calculator for pedicle screws using a surrogate ensemble approach.

PubMed

Varghese, Vicky; Ramu, Palaniappan; Krishnan, Venkatesh; Saravana Kumar, Gurunathan

2016-12-01

Pedicle screw instrumentation is widely used in the treatment of spinal disorders and deformities. Currently, the surgeon decides the holding power of instrumentation based on the perioperative feeling which is subjective in nature. The objective of the paper is to develop a surrogate model which will predict the pullout strength of pedicle screw based on density, insertion angle, insertion depth and reinsertion. A Taguchi's orthogonal array was used to design an experiment to find the factors effecting pullout strength of pedicle screw. The pullout studies were carried using polyaxial pedicle screw on rigid polyurethane foam block according to American society for testing of materials (ASTM F543). Analysis of variance (ANOVA) and Tukey's honestly significant difference multiple comparison tests were done to find factor effect. Based on the experimental results, surrogate models based on Krigging, polynomial response surface and radial basis function were developed for predicting the pullout strength for different combination of factors. An ensemble of these surrogates based on weighted average surrogate model was also evaluated for prediction. Density, insertion depth, insertion angle and reinsertion have a significant effect (p <0.05) on pullout strength of pedicle screw. Weighted average surrogate performed the best in predicting the pull out strength amongst the surrogate models considered in this study and acted as insurance against bad prediction. A predictive model for pullout strength of pedicle screw was developed using experimental values and surrogate models. This can be used in pre-surgical planning and decision support system for spine surgeon. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Magnesium Alloys as a Biomaterial for Degradable Craniofacial Screws

PubMed Central

Henderson, Sarah E.; Verdelis, Konstantinos; Maiti, Spandan; Pal, Siladitya; Chung, William L.; Chou, Da-Tren; Kumta, Prashant N.; Almarza, Alejandro J.

2014-01-01

Recently, magnesium (Mg) alloys have received significant attention as a potential biomaterial for degradable implants, and this study was directed at evaluating the suitability of Mg for craniofacial bone screws. The objective was to implant screws fabricated from commercially available Mg-alloys (pure Mg and AZ31) in-vivo in a rabbit mandible. First, Mg-alloy screws were compared to stainless steel screws in an in-vitro pull-out test and determined to have a similar holding strength (~40N). A finite element model of the screw was created using the pull-out test data, and the model can be used for future Mg-alloy screw design. Then, Mg-alloy screws were implanted for 4, 8, and 12 weeks, with two controls of an osteotomy site (hole) with no implant and a stainless steel screw implanted for 12 weeks. MicroCT (computed tomography) was used to assess bone remodeling and Mg-alloy degradation, both visually and qualitatively through volume fraction measurements for all time points. Histologic analysis was also completed for the Mg-alloys at 12 weeks. The results showed that craniofacial bone remodeling occurred around both Mg-alloy screw types. Pure Mg had a different degradation profile than AZ31, however bone growth occurred around both screw types. The degradation rate of both Mg-alloy screw types in the bone marrow space and the muscle were faster than in the cortical bone space at 12 weeks. Furthermore, it was shown that by alloying Mg, the degradation profile could be changed. These results indicate the promise of using Mg-alloys for craniofacial applications. PMID:24384125

A multi-species reactive transport model to estimate biogeochemical rates based on single-well push-pull test data

NASA Astrophysics Data System (ADS)

Phanikumar, Mantha S.; McGuire, Jennifer T.

2010-08-01

Push-pull tests are a popular technique to investigate various aquifer properties and microbial reaction kinetics in situ. Most previous studies have interpreted push-pull test data using approximate analytical solutions to estimate (generally first-order) reaction rate coefficients. Though useful, these analytical solutions may not be able to describe important complexities in rate data. This paper reports the development of a multi-species, radial coordinate numerical model (PPTEST) that includes the effects of sorption, reaction lag time and arbitrary reaction order kinetics to estimate rates in the presence of mixing interfaces such as those created between injected "push" water and native aquifer water. The model has the ability to describe an arbitrary number of species and user-defined reaction rate expressions including Monod/Michelis-Menten kinetics. The FORTRAN code uses a finite-difference numerical model based on the advection-dispersion-reaction equation and was developed to describe the radial flow and transport during a push-pull test. The accuracy of the numerical solutions was assessed by comparing numerical results with analytical solutions and field data available in the literature. The model described the observed breakthrough data for tracers (chloride and iodide-131) and reactive components (sulfate and strontium-85) well and was found to be useful for testing hypotheses related to the complex set of processes operating near mixing interfaces.

Push-Pull Locomotion for Vehicle Extrication

NASA Technical Reports Server (NTRS)

Creager, Colin M.; Johnson, Kyle A.; Plant, Mark; Moreland, Scott J.; Skonieczny, Krzysztof

2014-01-01

For applications in which unmanned vehicles must traverse unfamiliar terrain, there often exists the risk of vehicle entrapment. Typically, this risk can be reduced by using feedback from on-board sensors that assess the terrain. This work addressed the situations where a vehicle has already become immobilized or the desired route cannot be traversed using conventional rolling. Specifically, the focus was on using push-pull locomotion in high sinkage granular material. Push-pull locomotion is an alternative mode of travel that generates thrust through articulated motion, using vehicle components as anchors to push or pull against. It has been revealed through previous research that push-pull locomotion has the capacity for generating higher net traction forces than rolling, and a unique optical flow technique indicated that this is the result of a more efficient soil shearing method. It has now been found that pushpull locomotion results in less sinkage, lower travel reduction, and better power efficiency in high sinkage material as compared to rolling. Even when starting from an "entrapped" condition, push-pull locomotion was able to extricate the test vehicle. It is the authors' recommendation that push-pull locomotion be considered as a reliable back-up mode of travel for applications where terrain entrapment is a possibility.

Supplements to a Guide to Cultural and Environmental Interpretation in the U.S. Army Corps of Engineers.

DTIC Science & Technology

1984-05-01

visitors knew but chose the crowded areas out of habit without thinking about using less crowded alternatives ( goalI ) Stp2. As a group, the team members...it becomes - * - necessary to target particular audiences. In most cases, you will need to pull particular information from your visitor data when...symbols pulled distinguished by a multi-sided Chagall from a list of anticipated behaviors mosaic which, at the time of this study, (Figure A7). was

78 FR 42719 - Test Procedures for Showerheads, Faucets, Water Closets, Urinals, and Commercial Prerinse Spray...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-17

... showerhead must be manufactured such that a pushing or pulling force of 8 lbf or more is required to remove... mechanically retained at the point of manufacture such that a pulling or pushing force of 8 lbf or more is...

49 CFR 572.135 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... orientation angle may not exceed 20 degrees. (8) Attach the pull cable and the load cell as shown in Figure O4. (9) Apply a tension force in the midsagittal plane to the pull cable as shown in Figure O4 at any...

Push-Pull Effects of Three Plant Secondary Metabolites on Oviposition of the Potato Tuber Moth, Phthorimaea operculella

PubMed Central

Ma, Y.F.; Xiao, C.

2013-01-01

The push-pull effects of three plant secondary metabolites, azadirachtin, eucalyptol, and heptanal, on the oviposition choices of potato tubers by the potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) were tested in the laboratory. Azadirachtin at concentrations from 1.5 to 12 mg/L had a significant repellent effect on oviposition. Eucalyptol at concentrations from 3 to 12 mg/L promoted oviposition. Heptanal promoted oviposition at low concentrations from 0.1875 to 3.0 mg/L but repelled it at higher concentrations from 12 to 24 mg/L. The combination of azadirachtin (12 mg/L) with eucalyptol (3.0 mg/L) resulted in a significant pushpull effect of 56.3% on oviposition. The average maximum push-pull effects occurred with the combinations of azadirachtin with heptanal (12 and 0.375 mg/L, respectively; 38.7% push-pull effect), heptanal with eucalyptol (12 and 6 mg/L, respectively; 31.4% push-pull effect), and heptanal (high concentration) with heptanal (low concentration) (12.0 and 0.375 mg/L, respectively; 25% push-pull effect). PMID:24786822

Individual and institutional push and pull factors as predictors of retirement timing in Europe: A multilevel analysis.

PubMed

De Preter, Hanne; Van Looy, Dorien; Mortelmans, Dimitri

2013-12-01

The number of retired people in Europe has increased significantly in recent decades. It remains unclear, however, whether individuals are more likely to be pulled toward retirement by their expectations about life after retirement than they are to be pushed out of the labour market due to poor health or dislike of one's job. The fact that retirement timing differs rather considerably between European countries suggests that not only micro, but also macro push (i.e. labour market constraints) and pull (i.e. economic incentives) factors influence retirement decisions. This duality heightens the need to determine the influence of micro-level and macro-level push and pull indicators on the retirement timing of older workers (50+) in Europe. Results are obtained performing multilevel event history analysis using longitudinal micro data from the first (2004/05) and second (2006/07) waves of the Survey of Health, Ageing and Retirement in Europe and macro data derived from the Organisation for Economic Cooperation and Development (OECD) and Eurostat. The results indicate that at the individual level, older workers are pushed out due to health problems as well as being attracted towards retirement to spend time with their grandchildren. At the institutional level, financial incentives such as a high implicit tax on continued work and high expenditures on early exit schemes make retirement attractive, whereas the institutional push context is of lesser importance. © 2013.

Comparative Evaluation of Antiplaque Efficacy of Coconut Oil Pulling and a Placebo, Among Dental College Students: A Randomized Controlled Trial

PubMed Central

Kulkarni, Suhas; Madupu, Padma Reddy; Doshi, Dolar; Bandari, Srikanth Reddy; Srilatha, Adepu

2017-01-01

Introduction Oil pulling, has been extensively used as traditional Indian folk remedy since many years to prevent dental diseases and for strengthening teeth and gums. Aim To compare and evaluate antiplaque efficacy of coconut oil pulling with a placebo among dental students, in Hyderabad city of India. Materials and Methods A randomized controlled study was carried out among 40 dental students. Out of 40, 20 subjects were randomly assigned to study group and other 20 to control group. Subjects in the study group were given the coconut oil and control group a placebo, and advised to rinse for 10 minutes, once daily in the morning for a period of seven days. Plaque levels were assessed on day zero, third and seventh day using Turesky-Gilmore-Glickman Modification of the Quigley-Hein Plaque Index (1970) for both the groups. Results The mean plaque scores showed a significant difference at baseline, third day and seventh day among both study (p<0.001) and control groups (p<0.001). Group wise comparison revealed, though the mean plaque scores were low among study group on third day and seventh day on comparison with the control group, significant difference was noticed only on the seventh day. Furthermore, the mean percentage reduction of plaque scores were also significant only on the seventh day with a high mean plaque reduction among study groups (p<0.001). Conclusion Oil pulling is effective in controlling plaque levels. PMID:29207824

How to make auxetic fibre reinforced composites

NASA Astrophysics Data System (ADS)

Alderson, K. L.; Simkins, V. R.; Coenen, V. L.; Davies, P. J.; Alderson, A.; Evans, K. E.

2005-03-01

Auxetic composite materials can be produced either from conventional components via specially designed configurations or from auxetic components. This paper reviews manufacturing methods for both these scenarios. It then looks at the possibility of property enhancements in both low velocity impact and fibre pull out due to the negative Poisson's ratio. Tests revealed that auxetic carbon fibre composites made from commercially available prepreg show evidence of increased resistance to low velocity impact and static indentation with a smaller area of damage. Also, using auxetic fibres in composite materials is shown to produce a higher resistance to fibre pullout.

Test and analysis results for composite transport fuselage and wing structures

NASA Technical Reports Server (NTRS)

Deaton, Jerry W.; Kullerd, Susan M.; Madan, Ram C.; Chen, Victor L.

1992-01-01

Automated tow placement (ATP) and stitching of dry textile composite preforms followed by resin transfer molding (RTM) are being studied as cost effective manufacturing processes for obtaining damage tolerant fuselage and wing structures for transport aircraft. Data are presented to assess the damage tolerance of ATP and RTM fuselage elements with stitched-on stiffeners from compression tests of impacted three J-stiffened panels and from stiffener pull-off tests. Data are also presented to assess the damage tolerance of RTM wing elements which had stitched skin and stiffeners from impacted single stiffener and three blade stiffened compression tests and stiffener pull-off tests.

Fast Electromechanical Switches Based on Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Kaul, Anupama; Wong, Eric; Epp, Larry

2008-01-01

Electrostatically actuated nanoelectromechanical switches based on carbon nanotubes have been fabricated and tested in a continuing effort to develop high-speed switches for a variety of stationary and portable electronic equipment. As explained below, these devices offer advantages over electrostatically actuated microelectromechanical switches, which, heretofore, have represented the state of the art of rapid, highly miniaturized electromechanical switches. Potential applications for these devices include computer memories, cellular telephones, communication networks, scientific instrumentation, and general radiation-hard electronic equipment. A representative device of the present type includes a single-wall carbon nanotube suspended over a trench about 130 nm wide and 20 nm deep in an electrically insulating material. The ends of the carbon nanotube are connected to metal electrodes, denoted the source and drain electrodes. At bottom of the trench is another metal electrode, denoted the pull electrode (see figure). In the off or open switch state, no voltage is applied, and the nanotube remains out of contact with the pull electrode. When a sufficiently large electric potential (switching potential) is applied between the pull electrode and either or both of the source and drain electrodes, the resulting electrostatic attraction bends and stretches the nanotube into contact with the pull electrode, thereby putting the switch into the "on" or "closed" state, in which substantial current (typically as much as hundreds of nanoamperes) is conducted. Devices of this type for use in initial experiments were fabricated on a thermally oxidized Si wafer, onto which Nb was sputter-deposited for use as the pull-electrode layer. Nb was chosen because its refractory nature would enable it to withstand the chemical and thermal conditions to be subsequently imposed for growing carbon nanotubes. A 200- nm-thick layer of SiO2 was formed on top of the Nb layer by plasma-enhanced chemical vapor deposition. In the device regions, the SiO2 layer was patterned to thin it to the 20-nm trench depth. The trenches were then patterned by electron- beam lithography and formed by reactive- ion etching of the pattern through the 20-nm-thick SiO2 to the Nb layer.

Pull-Out Strength and Bond Behavior of Prestressing Strands in Prestressed Self-Consolidating Concrete

PubMed Central

Long, Wu-Jian; Khayat, Kamal Henri; Lemieux, Guillaume; Hwang, Soo-Duck; Xing, Feng

2014-01-01

With the extensive use of self-consolidating concrete (SCC) worldwide, it is important to ensure that such concrete can secure uniform in-situ mechanical properties that are similar to those obtained with properly consolidated concrete of conventional fluidity. Ensuring proper stability of SCC is essential to enhance the uniformity of in-situ mechanical properties, including bond to embedded reinforcement, which is critical for structural engineers considering the specification of SCC for prestressed applications. In this investigation, Six wall elements measuring 1540 mm × 2150 mm × 200 mm were cast using five SCC mixtures and one reference high-performance concrete (HPC) of normal consistency to evaluate the uniformity of bond strength between prestressing strands and concrete as well as the distribution of compressive strength obtained from cores along wall elements. The evaluated SCC mixtures used for casting wall elements were proportioned to achieve a slump flow consistency of 680 ± 15 mm and minimum caisson filling capacity of 80%, and visual stability index of 0.5 to 1. Given the spreads in viscosity and static stability of the SCC mixtures, the five wall elements exhibited different levels of homogeneity in in-situ compressive strength and pull-out bond strength. Test results also indicate that despite the high fluidity of SCC, stable concrete can lead to more homogenous in-situ properties than HPC of normal consistency subjected to mechanical vibration. PMID:28788223

Pull-Out Strength and Bond Behavior of Prestressing Strands in Prestressed Self-Consolidating Concrete.

PubMed

Long, Wu-Jian; Khayat, Kamal Henri; Lemieux, Guillaume; Hwang, Soo-Duck; Xing, Feng

2014-10-10

With the extensive use of self-consolidating concrete (SCC) worldwide, it is important to ensure that such concrete can secure uniform in-situ mechanical properties that are similar to those obtained with properly consolidated concrete of conventional fluidity. Ensuring proper stability of SCC is essential to enhance the uniformity of in-situ mechanical properties, including bond to embedded reinforcement, which is critical for structural engineers considering the specification of SCC for prestressed applications. In this investigation, Six wall elements measuring 1540 mm × 2150 mm × 200 mm were cast using five SCC mixtures and one reference high-performance concrete (HPC) of normal consistency to evaluate the uniformity of bond strength between prestressing strands and concrete as well as the distribution of compressive strength obtained from cores along wall elements. The evaluated SCC mixtures used for casting wall elements were proportioned to achieve a slump flow consistency of 680 ± 15 mm and minimum caisson filling capacity of 80%, and visual stability index of 0.5 to 1. Given the spreads in viscosity and static stability of the SCC mixtures, the five wall elements exhibited different levels of homogeneity in in-situ compressive strength and pull-out bond strength. Test results also indicate that despite the high fluidity of SCC, stable concrete can lead to more homogenous in-situ properties than HPC of normal consistency subjected to mechanical vibration.

Trichotillomania

MedlinePlus

... relief. People might have a brief feeling of satisfaction for a moment after pulling out their hair. ... gives the person a feeling of relief or satisfaction. The more the person gives in to the ...

Pull Out Negativity by Its Roots.

ERIC Educational Resources Information Center

DuFour, Rick; Burnette, Becky

2002-01-01

Principals are well-positioned to cultivate their schools' cultures. They must remain vigilant in rooting out the beginnings of negative culture, including such teacher attitudes and behaviors as not feeling responsible for student learning, preferring to work alone, wanting to protect their territory, and focusing on activity rather than results.…

DC dynamic pull-in instability of a dielectric elastomer balloon: an energy-based approach

NASA Astrophysics Data System (ADS)

Sharma, Atul Kumar; Arora, Nitesh; Joglekar, M. M.

2018-03-01

This paper reports an energy-based method for the dynamic pull-in instability analysis of a spherical dielectric elastomer (DE) balloon subjected to a quasi-statically applied inflation pressure and a Heaviside step voltage across the balloon wall. The proposed technique relies on establishing the energy balance at the point of maximum stretch in an oscillation cycle, followed by the imposition of an instability condition for extracting the threshold parameters. The material models of the Ogden family are employed for describing the hyperelasticity of the balloon. The accuracy of the critical dynamic pull-in parameters is established by examining the saddle-node bifurcation in the transient response of the balloon obtained by integrating numerically the equation of motion, derived using the Euler-Lagrange equation. The parametric study brings out the effect of inflation pressure on the onset of the pull-in instability in the DE balloon. A quantitative comparison between the static and dynamic pull-in parameters at four different levels of the inflation pressure is presented. The results indicate that the dynamic pull-in instability gets triggered at electric fields that are lower than those corresponding to the static instability. The results of the present investigation can find potential use in the design and development of the balloon actuators subjected to transient loading. The method developed is versatile and can be used in the dynamic instability analysis of other conservative systems of interest.

DC dynamic pull-in instability of a dielectric elastomer balloon: an energy-based approach.

PubMed

Sharma, Atul Kumar; Arora, Nitesh; Joglekar, M M

2018-03-01

This paper reports an energy-based method for the dynamic pull-in instability analysis of a spherical dielectric elastomer (DE) balloon subjected to a quasi-statically applied inflation pressure and a Heaviside step voltage across the balloon wall. The proposed technique relies on establishing the energy balance at the point of maximum stretch in an oscillation cycle, followed by the imposition of an instability condition for extracting the threshold parameters. The material models of the Ogden family are employed for describing the hyperelasticity of the balloon. The accuracy of the critical dynamic pull-in parameters is established by examining the saddle-node bifurcation in the transient response of the balloon obtained by integrating numerically the equation of motion, derived using the Euler-Lagrange equation. The parametric study brings out the effect of inflation pressure on the onset of the pull-in instability in the DE balloon. A quantitative comparison between the static and dynamic pull-in parameters at four different levels of the inflation pressure is presented. The results indicate that the dynamic pull-in instability gets triggered at electric fields that are lower than those corresponding to the static instability. The results of the present investigation can find potential use in the design and development of the balloon actuators subjected to transient loading. The method developed is versatile and can be used in the dynamic instability analysis of other conservative systems of interest.

Large-Scale CTRW Analysis of Push-Pull Tracer Tests and Other Transport in Heterogeneous Porous Media

NASA Astrophysics Data System (ADS)

Hansen, S. K.; Berkowitz, B.

2014-12-01

Recently, we developed an alternative CTRW formulation which uses a "latching" upscaling scheme to rigorously map continuous or fine-scale stochastic solute motion onto discrete transitions on an arbitrarily coarse lattice (with spacing potentially on the meter scale or more). This approach enables model simplification, among many other things. Under advection, for example, we see that many relevant anomalous transport problems may be mapped into 1D, with latching to a sequence of successive, uniformly spaced planes. On this formulation (which we term RP-CTRW), the spatial transition vector may generally be made deterministic, with CTRW waiting time distributions encapsulating all the stochastic behavior. We demonstrate the excellent performance of this technique alongside Pareto-distributed waiting times in explaining experiments across a variety of scales using only two degrees of freedom. An interesting new application of the RP-CTRW technique is the analysis of radial (push-pull) tracer tests. Given modern computational power, random walk simulations are a natural fit for the inverse problem of inferring subsurface parameters from push-pull test data, and we propose them as an alternative to the classical type curve approach. In particular, we explore the visibility of heterogeneity through non-Fickian behavior in push-pull tests, and illustrate the ability of a radial RP-CTRW technique to encapsulate this behavior using a sparse parameterization which has predictive value.

Cellulose acetate based 3-dimensional electrospun scaffolds for skin tissue engineering applications.

PubMed

Atila, Deniz; Keskin, Dilek; Tezcaner, Ayşen

2015-11-20

Skin defects that are not able to regenerate by themselves are among the major problems faced. Tissue engineering approach holds promise for treating such defects. Development of tissue-mimicking-scaffolds that can promote healing process receives an increasing interest in recent years. In this study, 3-dimensional electrospun cellulose acetate (CA) pullulan (PULL) scaffolds were developed for the first time. PULL was intentionally used to obtain 3D structures with adjustable height. It was removed from the electrospun mesh to increase the porosity and biostability. Different ratios of the polymers were electrospun and analyzed with respect to degradation, porosity, and mechanical properties. It has been observed that fiber diameter, thickness and porosity of scaffolds increased with increased PULL content, on the other hand this resulted with higher degradation of scaffolds. Mechanical strength of scaffolds was improved after PULL removal suggesting their suitability as cell carriers. Cell culture studies were performed with the selected scaffold group (CA/PULL: 50/50) using mouse fibroblastic cell line (L929). In vitro cell culture tests showed that cells adhered, proliferated and populated CA/PULL (50/50) scaffolds showing that they are cytocompatible. Results suggest that uncrosslinked CA/PULL (50/50) electrospun scaffolds hold potential for skin tissue engineering applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Characterization of SiC (SCS-6) Fiber Reinforced Reaction-Formed Silicon Carbide Matrix Composites

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay; Dickerson, Robert M.

1995-01-01

Silicon carbide (SCS-6) fiber reinforced-reaction formed silicon carbide matrix composites were fabricated using NASA's reaction forming process. Silicon-2 at a percent of niobium alloy was used as an infiltrant instead of pure silicon to reduce the amount of free silicon in the matrix after reaction forming. The matrix primarily consists of silicon carbide with a bi-modal grain size distribution. Minority phases dispersed within the matrix are niobium disilicide (NbSi2), carbon and silicon. Fiber push-out tests on these composites determined a debond stress of approx. 67 MPa and a frictional stress of approx. 60 MPa. A typical four point flexural strength of the composite is 297 MPa (43.1 KSi). This composite shows tough behavior through fiber pull out.

Shape optimization of electrostatically driven microcantilevers using simulated annealing to enhance static travel range

NASA Astrophysics Data System (ADS)

Trivedi, R. R.; Joglekar, M. M.; Shimpi, R. P.; Pawaskar, D. N.

2013-12-01

The objective of this paper is to present a systematic development of the generic shape optimization of elec- trostatically actuated microcantilever beams for extending their static travel range. Electrostatic actuators are widely used in micro electro mechanical system (MEMS) devices because of low power density and ease of fab- rication. However, their useful travel range is often restricted by a phenomenon known as pull-in instability. The Rayleigh- Ritz energy method is used for computation of pull-in parameters which includes electrostatic potential and fringing field effect. Appropriate width function and linear thickness functions are employed along the length of the non-prismatic beam to achieve enhanced travel range. Parameters used for varying the thick- ness and width functions are optimized using simulated annealing with pattern search method towards the end to refine the results. Appropriate penalties are imposed on the violation of volume, width, thickness and area constraints. Nine test cases are considered for demonstration of the said optimization method. Our results indicate that around 26% increase in the travel range of a non-prismatic beam can be achieved after optimiza- tion compared to that in a prismatic beam having the same volume. Our results also show an improvement in the pull-in displacement of around 5% compared to that of a variable width constant thickness actuator. We show that simulated annealing is an effective and flexible method to carry out design optimization of structural elements under electrostatic loading.

Drawbar Pull (DP) Procedures for Off-Road Vehicle Testing

NASA Technical Reports Server (NTRS)

Creager, Colin; Asnani, Vivake; Oravec, Heather; Woodward, Adam

2017-01-01

As NASA strives to explore the surface of the Moon and Mars, there is a continued need for improved tire and vehicle development. When tires or vehicles are being designed for off-road conditions where significant thrust generation is required, such as climbing out of craters on the Moon, it is important to use a standard test method for evaluating their tractive performance. The drawbar pull (DP) test is a way of measuring the net thrust generated by tires or a vehicle with respect to performance metrics such as travel reduction, sinkage, or power efficiency. DP testing may be done using a single tire on a traction rig, or with a set of tires on a vehicle; this report focuses on vehicle DP tests. Though vehicle DP tests have been used for decades, there are no standard procedures that apply to exploration vehicles. This report summarizes previous methods employed, shows the sensitivity of certain test parameters, and provides a body of knowledge for developing standard testing procedures. The focus of this work is on lunar applications, but these test methods can be applied to terrestrial and planetary conditions as well. Section 1.0 of this report discusses the utility of DP testing for off-road vehicle evaluation and the metrics used. Section 2.0 focuses on test-terrain preparation, using the example case of lunar terrain. There is a review of lunar terrain analogs implemented in the past and a discussion on the lunar terrain conditions created at the NASA Glenn Research Center, including methods of evaluating the terrain strength variation and consistency from test to test. Section 3.0 provides details of the vehicle test procedures. These consist of a review of past methods, a comprehensive study on the sensitivity of test parameters, and a summary of the procedures used for DP testing at Glenn.

Trichotillomania: Bizzare Patern of Hair Loss at 11-Year-old Girl.

PubMed

Zímová, Jana; Zímová, Pavlína

2016-06-01

Trichotillomania (TTM) is defined by the Diagnostics and Statistic Manual of Mental Disorders, 4th edition (DMS-IV) as hair loss from a patient`s repetitive self-pulling of hair. The disorder is included under anxiety disorders because it shares some obsessive-compulsive features. Patients have the tendency towards feelings of unattractiveness, body dissatisfaction, and low self-esteem (1,2). It is a major psychiatric problem, but many patients with this disorder first present to a dermatologist. An 11-year-old girl came to our department with a 2-month history of diffuse hair loss on the frontoparietal and parietotemporal area (Figure 1). She had originally been examined by a pediatrician with the diagnosis of alopecia areata. The patient`s personal history included hay fever and shortsightedness, and she suffered from varicella and mononucleosis. Nobody in the family history suffered from alopecia areata, but her father has male androgenetic alopecia (Norwood/Hamilton MAGA C3F3). The mother noticed that the child had had changeable mood for about 2 months and did not want to communicate with other persons in the family. The family did not have any pet at home. At school, her favorite subjects were Math and Computer Studies. She did not like Physical Education and did not participate in any sport activities during her free time. This was very strange because she was obese (body-mass index (BMI) 24.69). She was sometimes angry with her 13-year-old sister who had better results at school. The girl had suddenly started to wear a blue scarf. The parents did not notice that she pulled out her hair at home. Dermatological examination of the capillitium found a zone of incomplete alopecia in the frontoparietal and parietotemporal area, without inflammation, desquamation, and scaring. Hairs were of variable length (Figure 1). There was a patch of incomplete alopecia above the forehead between two stripes of hair of variable length (Figure 2). The hair pull test was negative along the edges of the alopecia. Mycological examination from the skin capillitium was negative. The trichoscopy and skin biopsy of the parietotemporal region of the capillitium (Figure 3) confirmed trichotillomania. Laboratory tests (blood count, iron, ferritin, transferrin, selenium, zinc, vitamin B12, folic acid, serology and hormones of thyroid gland) were negative. We referred the girl for ophthalmologic and psychological examination. Ophthalmologic examination proved that there was no need to add any more diopters. The psychological examination provided us with a picture in which she drew her family (Figure 4). The strongest authority in the family was the mother because she looked after the girls for most of the day. She was in the first place in the picture. The father had longer working hours and spent more time outside the home. He worked as a long vehicle driver. He was in the second place in the picture. There was sibling rivalry between the girls, but the parents did not notice this problem and preferred the older daughter. She was successful at school and was prettier (slim, higher, curly brown hair, without spectacles). Our 11-years-old patient noticed all these differences between them, but at her level of mental development was not able to cope with this problem. She wanted to be her sister's equal. The sister is drawn in the picture in the third place next to father, while the patient's own figure was drawn larger and slim even though she was obese. Notably, all three female figures had very nice long brown hair. It seemed that the mother and our patient had better quality of hair and more intense color than the sister in the drawing. The only hairless person in the picture was the father. The girl did not want to talk about her problems and feelings at home. Then it was confirmed that our patient was very sensitive, anxious, willful, and withdrawn. She was interested in her body and very perceptive of her physical appearance. From the psychological point of view, the parents started to pay more interest to their younger daughter and tried to understand and help her. After consultation with the psychiatrist, we did not start psychopharmacologic therapy for trichotillomania; instead, we started treatment with cognitive behavioral therapy, mild shampoo, mild topical steroids (e.g. hydrocortisone butyrate 0.1%) in solution and methionine in capsules. With parents' cooperation, the treatment was successful. The name trichotillomania was first employed by the French dermatologist Francois Henri Hallopeau in 1889, who described a young man pulling his hair out in tufts (3-5). The word is derived from the Greek thrix (hair), tillein (to pull), and mania (madness) (5). The prevalence of TTM in the general adult population ranges from 0.6% to 4%, and 2-4% of the general psychiatric outpatient population meet the criteria for TTM (2-5). The prevalence among children and adolescents has been estimated at less than 1% (5). The disease can occur at any age and in any sex. The age of onset of hair pulling is significantly later for men than for women (3). There are three subsets of age: preschool children, preadolescents to young adults, and adults. The mean age of onset is pre-pubertal. It ranges from 8 to 13 years (on average 11.3 years) (2-5). The occurrence of hair-pulling in the first year of life is a rare event, probably comprising <1% of cases (5). The etiology of TTM is complex and may be triggered by a psychosocial stressor within the family, such as separation from an attachment figure, hospitalization of the child or parent, birth of a younger sibling, sibling rivalry, moving to a new house, or problems with school performance. It has been hypothesized that the habit may begin with "playing" with the hair, with later chronic pulling resulting in obvious hair loss (2). Environment is a factor because children usually pull their hair when alone and in relaxed surroundings. The bedroom, bathroom, or family room are "high-risk" situations for hair-pulling (5). Men and women also differed in terms of the hair pulling site (men pull hair from the stomach/back and the moustache/beard areas, while women pull from the scalp) (3). Pulling hair from siblings, pets, dolls, and stuffed animals has also been documented, often occurring in the same pattern as in the patient (5). Genetic factors contributing to the development of TTM are mutations of the SLITRK1 gene, which plays a role in cortex development and neuronal growth. The protein SAPAP3 has been present in 4.2% of TTM cases and patients with obsessive-compulsive disorder (OCD). It may be involved in the development of the spectrum of OCD. A significantly different concordance rate for TTM was found in monozygotic (38.1%) compared with dizygotic (0%) twins in 34 pairs (3). The core diagnostic feature is the repetitive pulling of hairs from one`s own body, resulting in hair loss. The targeted hair is mostly on the scalp (75%), but may also be from the eyebrows (42%), eyelashes (53%), beard (10%), and pubic area (17%) (3,5). There are three subtypes of hair pulling - early onset, automatic, and focused. Diagnostic criteria for TTM according to DSM-IV criteria are (2,3,5): 1) recurrent pulling of one`s hair resulting in noticeable hair loss; 2) an increasing sense of tension immediately prior to pulling out the hair or when attempting to resist the behavior; 3) pleasure, gratification, or relief when pulling out the hair; 4) the disturbance is not better accounted for by another mental disorder and is not due to a general medical condition (e.g., a dermatologic condition); 5) the disturbance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning. The differential diagnosis includes alopecia areata (Table 1) (6), tinea capitis, telogen effluvium, secondary syphilis, traction alopecia, loose anagen syndrome, lichen planopilaris, alopecia mucinosa, and scleroderma (2-5). Biopsy of an involved area (ideally from a recent site of hair loss) can help to confirm the diagnosis (5). On histologic examination, there are typically increased numbers of catagen and telogen hairs without evidence of inflammation. Chronic hair pulling induces a catagen phase, and more hairs will be telogen hairs. Pigment casts and empty anagen follicles are often seen. Perifollicular hemorrhage near the hair bulb is an indicator of TTM (2). Complications of TTM are rare, but they comprise secondary bacterial infections with regional lymphadenopathy as a result of picking and scratching at the scalp. Many patients play with and ingest the pulled hairs (e.g. touching the hair to lips, biting, and chewing). Trichophagia (ingestion of the hair) can lead to a rare complication named trichobezoar (a "hair ball" in stomach). This habit is present in approximately 5% to 30% of adult patients, but it is less frequent in children. Patient with trichophagia present with pallor, nausea, vomiting, anorexia, and weight loss. Radiologic examination and gastroscopy should not be delayed (2,4,5). The management of the disease is difficult and requires strong cooperation between the physician, patient, and parents. The dermatologist cannot take part in the therapy, strictly speaking, but without the psychological, psychopharmacologic, and topic dermatologic treatment a vicious circle will be perpetuated.

Low cycle fatigue properties of type 316 stainless steel in vacuum

NASA Astrophysics Data System (ADS)

Furuya, Kazuo; Nagata, Norio; Watanabe, Ryoji

1980-04-01

Low cycle fatigue tests in vacuum were carried out on Type 316 stainless steel under the push-pull type, strain-controlled, continuous cycling mode in the temperature range from room temperature to 1073 K and strain rate from 5 × 10 -3 to 5 × 10 -5/s . Little temperature dependence of the fatigue life at a given plastic strain range is observed. The fatigue life decreases with decreasing strain rate at room temperature and 823 K, but shows little change at 973 and 1073 K. The fracture mode is transgranular in most cases, but an indication of intergranular cracking is observed in the specimens tested at 1073 K and at the lowest strain rate. The results are treated by the general adsorption model.

42 CFR 84.151 - Harness test; minimum requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... withstand a pull of 113 kg. (250 pounds) for 30 minutes without failure. (2) Belts, rings, and attachments... minutes without separating, and the hose attachments shall be arranged so that the pull or drag of the... attachment of the line shall permit dragging the maximum length of hose considered for approval over a...

Experiential Avoidance as a Mediator of Relationships between Cognitions and Hair-Pulling Severity

ERIC Educational Resources Information Center

Norberg, Melissa M.; Wetterneck, Chad T.; Woods, Douglas W.; Conelea, Christine A.

2007-01-01

Cognitive-behavioral models suggest that certain cognitions and beliefs are functionally related to hair pulling in persons with trichotillomania (TTM), but little empirical data have been collected to test such claims. This study assessed dysfunctional beliefs about appearance, shameful cognitions, and fear of negative evaluation and their…

Laboratory evaluation techniques to investigate the spatial potential of repellents for push & pull mosquito control systems

USDA-ARS?s Scientific Manuscript database

A protocol has been developed for the indoor evaluation of candidate spatial repellents intended for use in push and pull systems. Single treatments (catnip oil, 1-methylpiperazine and homopiperazine) and a mixture of catnip oil and homopiperazine were tested with yellow-fever mosquitoes (Aedes aegy...

A Qualitative Case Study on the Implementation of a Priority Seating Program at an NCAA Division I School

DTIC Science & Technology

2004-08-01

green earth.. .It’s Badger hockey fans who research the name of the mother of an opposing team’s goalie so as to better inform their heckling.. .It’s the...Center and is information pulled directly from the aforementioned document ’The Kohl Center: Basketball Ticket Plan." 84 The athletic department began...our development staff which was initially housed over at the UW Foundation.. .we really hammered out the details and logistics of pulling a

Basic Skills Resource Center: Teaching Reading Comprehension to Adults in Basic Skills Courses

DTIC Science & Technology

1985-08-01

paper trash out to be burned 4. A hockey coach telling his players to keep shooting at the goalie . What skill, or skills, did you use to answer the...With this exercise the learner is introduced to the idea of INFERENCE. The learner’s mind must INFER the rest of the idea in order to pull the four...to pull the ideas of the paragraph together. (Lesson 3 will teach learners how to construct an "umbrella" idea to act as a topic sentence for readings

Patterned-string tasks: relation between fine motor skills and visual-spatial abilities in parrots.

PubMed

Krasheninnikova, Anastasia

2013-01-01

String-pulling and patterned-string tasks are often used to analyse perceptual and cognitive abilities in animals. In addition, the paradigm can be used to test the interrelation between visual-spatial and motor performance. Two Australian parrot species, the galah (Eolophus roseicapilla) and the cockatiel (Nymphicus hollandicus), forage on the ground, but only the galah uses its feet to manipulate food. I used a set of string pulling and patterned-string tasks to test whether usage of the feet during foraging is a prerequisite for solving the vertical string pulling problem. Indeed, the two species used techniques that clearly differed in the extent of beak-foot coordination but did not differ in terms of their success in solving the string pulling task. However, when the visual-spatial skills of the subjects were tested, the galahs outperformed the cockatiels. This supports the hypothesis that the fine motor skills needed for advanced beak-foot coordination may be interrelated with certain visual-spatial abilities needed for solving patterned-string tasks. This pattern was also found within each of the two species on the individual level: higher motor abilities positively correlated with performance in patterned-string tasks. This is the first evidence of an interrelation between visual-spatial and motor abilities in non-mammalian animals.

Molecular mechanics of silk nanostructures under varied mechanical loading.

PubMed

Bratzel, Graham; Buehler, Markus J

2012-06-01

Spider dragline silk is a self-assembling tunable protein composite fiber that rivals many engineering fibers in tensile strength, extensibility, and toughness, making it one of the most versatile biocompatible materials and most inviting for synthetic mimicry. While experimental studies have shown that the peptide sequence and molecular structure of silk have a direct influence on the stiffness, toughness, and failure strength of silk, few molecular-level analyses of the nanostructure of silk assemblies, in particular, under variations of genetic sequences have been reported. In this study, atomistic-level structures of wildtype as well as modified MaSp1 protein from the Nephila clavipes spider dragline silk sequences, obtained using an in silico approach based on replica exchange molecular dynamics and explicit water molecular dynamics, are subjected to simulated nanomechanical testing using different force-control loading conditions including stretch, pull-out, and peel. The authors have explored the effects of the poly-alanine length of the N. clavipes MaSp1 peptide sequence and identify differences in nanomechanical loading conditions on the behavior of a unit cell of 15 strands with 840-990 total residues used to represent a cross-linking β-sheet crystal node in the network within a fibril of the dragline silk thread. The specific loading condition used, representing concepts derived from the protein network connectivity at larger scales, have a significant effect on the mechanical behavior. Our analysis incorporates stretching, pull-out, and peel testing to connect biochemical features to mechanical behavior. The method used in this study could find broad applications in de novo design of silk-like tunable materials for an array of applications. Copyright © 2011 Wiley Periodicals, Inc.

The effect of hierarchical micro/nanosurface titanium implant on osseointegration in ovariectomized sheep.

PubMed

Xiao, J; Zhou, H; Zhao, L; Sun, Y; Guan, S; Liu, B; Kong, L

2011-06-01

Hydrofluoric etching and anodized hierarchical micro/nanotextured surface titanium implant was placed in mandibles of ovariectomized sheep for 12 weeks, and it showed improved osseointegration by resonance frequency analysis (RFA), microcomputed tomography (micro-CT) evaluation, histomorphometry, and biomechanical test. This study aimed to investigate the effects of micro/nanotextured titanium implant on osseointegration in ovariectomized (OVX) sheep. The hierarchical micro/nanotextured surface of titanium implant was fabricated by acid in 0.5% (w/v) hydrofluoric (HF) and anodized in HF acid electrolytes with a DC power of 20 V, and the machined surface implants with no treatment served as control group. The implants were placed in mandibles of OVX sheep, respectively. Twelve weeks after implantation, RFA, microcomputed tomography, histomorphometry, and biomechanical tests were applied to detect the osseointegration of the two groups. The implant stability quotient (ISQ) values, the maximum pull-out forces, and the bone-implant contact (BIC) were 65.5 ± 6.3, 490.6 ± 72.7 N, and 58.31 ± 5.79% in the micro/nanogroup and 58.3 ± 8.9, 394.5 ± 54.5 N, and 46.85 ± 5.04% in the control group, respectively. There was no significant difference between the two groups in ISQ values (p > 0.05), but in the micro/nanogroup, the maximal pull-out force and the BIC were increased significantly (p < 0.05 or p < 0.01). Micro-CT analysis showed that the bone volume ratio and the trabecular number increased significantly (p < 0.01), and the trabecular separation decreased significantly (p < 0.05) in the micro/nanogroup. Implant modification by HF acid etching and anodization to form a hierarchical micro/nanotextured surface could improve titanium implant osseointegration in OVX sheep 12 weeks after implantation.

Origin of tensile strength of a woven sample cut in bias directions

PubMed Central

Pan, Ning; Kovar, Radko; Dolatabadi, Mehdi Kamali; Wang, Ping; Zhang, Diantang; Sun, Ying; Chen, Li

2015-01-01

Textile fabrics are highly anisotropic, so that their mechanical properties including strengths are a function of direction. An extreme case is when a woven fabric sample is cut in such a way where the bias angle and hence the tension loading direction is around 45° relative to the principal directions. Then, once loaded, no yarn in the sample is held at both ends, so the yarns have to build up their internal tension entirely via yarn–yarn friction at the interlacing points. The overall fabric strength in such a sample is a result of contributions from the yarns being pulled out and those broken during the process, and thus becomes a function of the bias direction angle θ, sample width W and length L, along with other factors known to affect fabric strength tested in principal directions. Furthermore, in such a bias sample when the major parameters, e.g. the sample width W, change, not only the resultant strengths differ, but also the strength generating mechanisms (or failure types) vary. This is an interesting problem and is analysed in this study. More specifically, the issues examined in this paper include the exact mechanisms and details of how each interlacing point imparts the frictional constraint for a yarn to acquire tension to the level of its strength when both yarn ends were not actively held by the testing grips; the theoretical expression of the critical yarn length for a yarn to be able to break rather than be pulled out, as a function of the related factors; and the general relations between the tensile strength of such a bias sample and its structural properties. At the end, theoretical predictions are compared with our experimental data. PMID:26064655

Effect of thermally growth oxides (TGO) on adhesion strength for high purity yitria stabilised zirconia (YSZ) and rare - Earth lanthanum zirconates (LZ) multilayer thermal barrier coating before and after isothermal heat treatment

NASA Astrophysics Data System (ADS)

Yunus, Salmi Mohd; Johari, Azril Dahari; Husin, Shuib

2017-12-01

Investigation on the effect of Thermally Growth Oxides (TGO) on the adhesion strength for thermal barrier coating (TBC) was carried out. The TBC under studied was the multilayer systems which consist of NiCrAlY bond coat and YSZ/LZ ceramic coating deposited on Ni-based superalloy substrates. The development of thermally growth oxides (TGO) for both TBC systems after isothermal heat treatment was measured. Isothermal heat treatment was carried out at 1100 ˚C for 100 hours to age the samples. ASTM D4541: Standard Test Method for Pull-off Strength of Coatings using Portable Adhesion Tester was used to measure the adhesion strength of both TBC systems before and after heat treatment. The effect of the developed TGO on the measured adhesion strength was examined and correlation between them was established individually for both TBC systems. The failure mechanism of the both system was also identified; either cohesive or adhesive or the combination of both. The results showed that TGO has more than 50% from the bond coat layer for rare-earth LZ system compared to the typical YSZ system, which was less than 10 % from the bond coat layer. This leads to the lower adhesion strength of rare-earth LZ coating system compared to typical YSZ system. Failure mechanism during the pull-off test also was found to be different for both TBC systems. The typical YSZ system experienced cohesive failure whereas the rare-earth LZ system experienced the combination of cohesive and adhesive failure.

Influence of post pattern and resin cement curing mode on the retention of glass fibre posts.

PubMed

Poskus, L T; Sgura, R; Paragó, F E M; Silva, E M; Guimarães, J G A

2010-04-01

To evaluate the influence of post design and roughness and cement system (dual- or self-cured) on the retention of glass fibre posts. Two tapered and smooth posts (Exacto Cônico No. 2 and White Post No. 1) and two parallel-sided and serrated posts (Fibrekor 1.25 mm and Reforpost No. 2) were adhesively luted with two different resin cements--a dual-cured (Rely-X ARC) and a self-cured (Cement Post)--in 40 single-rooted teeth. The teeth were divided into eight experimental groups (n = 5): PFD--Parallel-serrated-Fibrekor/dual-cured; PRD--Parallel-serrated-Reforpost/dual-cured; TED--Tapered-smooth-Exacto Cônico/dual-cured; TWD--Tapered-smooth-White Post/dual-cured; PFS--Parallel-serrated-Fibrekor/self-cured; PRS--Parallel-serrated-Reforpost/self-cured; TES--Tapered-smooth-Exacto Cônico/self-cured; TWS--Tapered-smooth-White Post/self-cured. The specimens were submitted to a pull-out test at a crosshead speed of 0.5 mm min(-1). Data were analysed using analysis of variance and Bonferroni's multiple comparison test (alpha = 0.05). Pull-out results (MPa) were: PFD = 8.13 (+/-1.71); PRD = 8.30 (+/-0.46); TED = 8.68 (+/-1.71); TWD = 9.35 (+/-1.99); PFS = 8.54 (+/-2.23); PRS = 7.09 (+/-1.96); TES = 8.27 (+/-3.92); TWS = 7.57 (+/-2.35). No statistical significant difference was detected for posts and cement factors and their interaction. The retention of glass fibre posts was not affected by post design or surface roughness nor by resin cement-curing mode. These results imply that the choice for serrated posts and self-cured cements is not related to an improvement in retention.

Prognostic factors of arthroscopic pull-out repair for a posterior root tear of the medial meniscus.

PubMed

Moon, Hong-Kyo; Koh, Yong-Gon; Kim, Yong-Chan; Park, Young-Sik; Jo, Seung-Bae; Kwon, Sae-Kwang

2012-05-01

Repair of a posterior root tear of the medial meniscus (MRT) decreases peak contact pressure by restoring hoop tension and is expected to prevent progression to osteoarthritis. The purposes of this study were (1) to report the clinical and magnetic resonance imaging (MRI) results of arthroscopic pull-out repair of the MRT and (2) to identify prognostic factors of poor outcome. Case series; Level of evidence, 4. Fifty-one patients (47 women, 4 men) who underwent arthroscopic pull-out repair of the MRT by a single surgeon were enrolled. Mean follow-up after surgery was 33 months (range, 24-44 months). To identify factors affecting final outcome, patient-specific factors, such as gender, age, body mass index, meniscus extrusion, extrusion increase, subchondral edema, degree of varus alignment (<5° or >5°), and cartilage status in the medial compartment (Outerbridge grade 1 or 2 lesion vs grade 3 or 4 lesion), were investigated. Final clinical outcomes were determined using a visual analog scale (VAS) for pain and patient satisfaction scores, American Knee Society (AKS) scores, and Lysholm scores, and MRI outcomes were determined by evaluating meniscus extrusion and articular cartilage status. Multiple regression analysis was performed to identify variables that independently affected clinical and MRI-determined outcomes. All clinical outcome measures significantly improved after surgery. Patients with Outerbridge grade 3 or 4 chondral lesions had poorer results than those with grade 1 or 2 lesions in terms of AKS function and Lysholm scores. Patients with varus alignment of >5° had poorer results than those with varus alignment of <5° in terms of VAS satisfaction, AKS function, and Lysholm scores. Mean meniscus extrusion increased from 3.6 mm preoperatively to 5.0 mm postoperatively. Chondral lesions progressed in 3 (9.7%) of 31 patients. Preoperative meniscus extrusion was found to be positively correlated with final extrusion. At a mean follow-up of 33 months after pull-out repair, extrusion of the meniscus was found to have progressed. Nevertheless, this technique provided patients with a clinical benefit. Outerbridge grade 3 or 4 chondral lesions and varus alignment of >5° were found to independently predict an inferior clinical outcome.

Dropping Out of School in Southern Ghana: The Push-Out and Pull-Out Factors. CREATE Pathways to Access. Research Monograph No. 55

ERIC Educational Resources Information Center

Ananga, Eric

2011-01-01

Addressing school dropout has been one of the most controversial elements of policy since the introduction of free compulsory universal basic education (FCUBE) in Ghana. However, research that utilises qualitative biographical detail surrounding irregular attendance and the critical events in the process that lead to dropout in Ghana is limited. I…

Women "Opting out" of Academia: At What Cost?

ERIC Educational Resources Information Center

Schneider, Beth Z.; Carden, William; Francisco, Alyson; Jones, Thomas O., Jr.

2011-01-01

Previous research has examined the phenomenon of women "opting out" of the corporate environment. Much of this research has examined both "pull" factors--those of home and family life, and "push" factors--those within the organization which create a competitive environment where women feel they cannot achieve the same measure of success as their…

Title I Institutionalized Facilities Program. O.E.E. Evaluation Report, 1981-82.

ERIC Educational Resources Information Center

New York City Board of Education, Brooklyn, NY. Office of Educational Evaluation.

This report documents the 1981-82 evaluation of the Elementary and Secondary Education Act, Title I, Part B, Institutional Facilities Program carried out through the Division of Special Education of the New York City public schools. Using a diagnostic-prescriptive methodology, the program provided after-school and pull-out individualized remedial…

Finding More Joy in Teaching Children

ERIC Educational Resources Information Center

Baumgartner, Jennifer J.; DiCarlo, Cynthia F.; Apavaloaie, Loredana

2011-01-01

Early childhood professionals are familiar with finding and appreciating daily moments of joy. Teachers smile inside and out when toddlers are able to pull up their own pants, preschoolers write their names for the first time, or kindergarteners figure out how to make complicated patterns with blocks. Working with young children can also be very…

Experimetal study on the FRP-concrete bond behavior under repeated loadings

NASA Astrophysics Data System (ADS)

Lee, J.-Y.; Yi, C.-K.; Cheong, Y.-G.

2009-11-01

In this study, the effects of repeated loads on the FRP-concrete bond strength were investigated experimentally by direct pull out tests according to CSA S806-02. A conventional reinforcing steel bar and two types of glass-fiber-reinforced plastic (GFRP) bars were embedded in concrete and tested under four different loading patterns. The bond strength-slip curves of the bars were obtained and analyzed. The results showed that the maximum bond strengths under the repeated loads differed from those obtained under monotonic ones. In addition, noticeable differences in degradation of the bond strength with respect to the magnitude of slip were observed between the different bar types tested. On the basis of an image analysis of failure surfaces, they were attributed to the different bond failure mechanisms associated with the steel and GFRP bars.

Quantification of the tug-back by measuring the pulling force and micro computed tomographic evaluation.

PubMed

Jeon, Su-Jin; Moon, Young-Mi; Seo, Min-Seock

2017-11-01

The aims of this study were to quantify tug-back by measuring the pulling force and investigate the correlation of clinical tug-back pulling force with in vitro gutta-percha (GP) cone adaptation score using micro-computed tomography (µCT). Twenty-eight roots from human single-rooted teeth were divided into 2 groups. In the ProTaper Next (PTN) group, root canals were prepared with PTN, and in the ProFile (PF) group, root canals were prepared using PF ( n = 14). The degree of tug-back was scored after selecting taper-matched GP cones. A novel method using a spring balance was designed to quantify the tug-back by measuring the pulling force. The correlation between tug-back scores, pulling force, and percentage of the gutta-percha occupied area (pGPOA) within apical 3 mm was investigated using µCT. The data were analyzed using Pearson's correlation analysis, one-way analysis of variance (ANOVA) and Tukey's test. Specimens with a strong tug-back had a mean pulling force of 1.24 N (range, 0.15-1.70 N). This study showed a positive correlation between tug-back score, pulling force, and pGPOA. However, there was no significant difference in these factors between the PTN and PF groups. Regardless of the groups, pGPOA and pulling force were significantly higher in the specimens with a higher tug-back score ( p < 0.05). The degree of subjective tug-back was a definitive determinant for master cone adaptation in the root canal. The use of the tug-back scoring system and pulling force allows the interpretation of subjective tug-back in a more objective and quantitative manner.

Performance of the Boeing LRV wheels in a lunar soil simulant. Report 2: Effects of speed, Wheel load, and soil

NASA Technical Reports Server (NTRS)

Melzer, K.

1971-01-01

Two nearly identical Boeing-GM wire-mesh Lunar Roving Vehicle (LRV) wheels were laboratory tested in a lunar soil simulant to determine the influence of wheel speed and acceleration, wheel load, presence of a fender, travel direction, and soil strength on the wheel performance. Constant-slip and three types of programmed-slip tests were conducted with a single-wheel dynamometer system. Test results indicated that performance of single LRV wheels in terms of pull coefficient, power number, and efficiency were not influenced by wheel speed and acceleration, travel direction, the presence of a fender, or wheel load. Of these variables, only load influenced sinkage, which increased with increasing load. For a given slip, the pull coefficient and power number increased with increasing soil strength. However, for a given pull coefficient or slope, slip was less in firmer soil; thus, the power number decreased and efficiency increased with increasing soil strength.

Gelatin capsule in stomach (image)

MedlinePlus

... detect the presence of intestinal parasites. A weighted gelatin capsule attached to a string is swallowed and left in place. After about 4 hours, the gelatin capsule is pulled out of the stomach by ...

Strength, power, and muscular endurance exercise and elite rowing ergometer performance.

PubMed

Lawton, Trent W; Cronin, John B; McGuigan, Michael R

2013-07-01

Knowledge of the relationship between weight room exercises and various rowing performance measures is limited; this information would prove useful for sport-specific assessment of individual needs and exercise prescription. The purpose of this study was to establish strength, power, and muscular endurance exercises for weight room training, which are strong determinants of success in specific performance measures used to assess elite rowers. Nineteen heavyweight elite males determined their repetition maximum (RM) loads for exercises using a Concept 2 DYNO [5, 30, 60 and 120RM leg pressing and seated arm pulling (in Joules)] and free weights [1RM power clean (in kilograms) and 6RM bench pull (in kilograms and watts)]. Rowing performance measures included a 7-stage blood lactate response ergometer test (aerobic condition), time trials (500, 2000, and 5000 m), a peak stroke power test, and a 60-minute distance trial. Pearson correlation moments (r ≥ 0.7) and stepwise multiple linear regression calculations (R ≥ 50%) were used to establish strong common variances between weight room exercises and rowing ergometer performance (p ≤ 0.05). Weight room exercises were strong predictors of 2000-m, 500-m time (in seconds), and peak stroke power performance measures only. Bench pull power (in watts) and 1RM power clean (in kilograms) were the best 2-factor predictors of peak stroke power (R = 73%; standard error of the estimates [SEE] = 59.6 W) and 500 m (R = 70%; SEE = 1.75 seconds); while 5RM leg pressing (in Joules) and either 6RM bench pull (kg) or 60RM seated arm pulling (in Joules) the best predictors of 2000 m (R = 59%; SEE = 6.3 seconds and R = 57%; SEE = 6.4 seconds, respectively). Recommended exercises for weight room training include a 1RM power clean, 6RM bench pull, 5RM leg press, and 60RM seated arm pulling.

Sequence-dependent folding landscapes of adenine riboswitch aptamers.

PubMed

Lin, Jong-Chin; Hyeon, Changbong; Thirumalai, D

2014-04-14

Expression of a large fraction of genes in bacteria is controlled by riboswitches, which are found in the untranslated region of mRNA. Structurally riboswitches have a conserved aptamer domain to which a metabolite binds, resulting in a conformational change in the downstream expression platform. Prediction of the functions of riboswitches requires a quantitative description of the folding landscape so that the barriers and time scales for the conformational change in the switching region in the aptamer can be estimated. Using a combination of all atom molecular dynamics (MD) and coarse-grained model simulations we studied the response of adenine (A) binding add and pbuE A-riboswitches to mechanical force. The two riboswitches contain a structurally similar three-way junction formed by three paired helices, P1, P2, and P3, but carry out different functions. Using pulling simulations, with structures generated in MD simulations, we show that after P1 rips the dominant unfolding pathway in the add A-riboswitch is the rupture of P2 followed by unraveling of P3. In the pbuE A-riboswitch, after P1 unfolds P3 ruptures ahead of P2. The order of unfolding of the helices, which is in accord with single molecule pulling experiments, is determined by the relative stabilities of the individual helices. Our results show that the stability of isolated helices determines the order of assembly and response to force in these non-coding regions. We use the simulated free energy profile for the pbuE A-riboswitch to estimate the time scale for allosteric switching, which shows that this riboswitch is under kinetic control lending additional support to the conclusion based on single molecule pulling experiments. A consequence of the stability hypothesis is that a single point mutation (U28C) in the P2 helix of the add A-riboswitch, which increases the stability of P2, would make the folding landscapes of the two riboswitches similar. This prediction can be tested in single molecule pulling experiments.

Force feedback effects on single molecule hopping and pulling experiments

NASA Astrophysics Data System (ADS)

Rico-Pasto, M.; Pastor, I.; Ritort, F.

2018-03-01

Single-molecule experiments with optical tweezers have become an important tool to study the properties and mechanisms of biological systems, such as cells and nucleic acids. In particular, force unzipping experiments have been used to extract the thermodynamics and kinetics of folding and unfolding reactions. In hopping experiments, a molecule executes transitions between the unfolded and folded states at a preset value of the force [constant force mode (CFM) under force feedback] or trap position [passive mode (PM) without feedback] and the force-dependent kinetic rates extracted from the lifetime of each state (CFM) and the rupture force distributions (PM) using the Bell-Evans model. However, hopping experiments in the CFM are known to overestimate molecular distances and folding free energies for fast transitions compared to the response time of the feedback. In contrast, kinetic rate measurements from pulling experiments have been mostly done in the PM while the CFM is seldom implemented in pulling protocols. Here, we carry out hopping and pulling experiments in a short DNA hairpin in the PM and CFM at three different temperatures (6 °C, 25 °C, and 45 °C) exhibiting largely varying kinetic rates. As expected, we find that equilibrium hopping experiments in the CFM and PM perform well at 6 °C (where kinetics are slow), whereas the CFM overestimates molecular parameters at 45 °C (where kinetics are fast). In contrast, nonequilibrium pulling experiments perform well in both modes at all temperatures. This demonstrates that the same kind of feedback algorithm in the CFM leads to more reliable determination of the folding reaction parameters in irreversible pulling experiments.

Force feedback effects on single molecule hopping and pulling experiments.

PubMed

Rico-Pasto, M; Pastor, I; Ritort, F

2018-03-28

Single-molecule experiments with optical tweezers have become an important tool to study the properties and mechanisms of biological systems, such as cells and nucleic acids. In particular, force unzipping experiments have been used to extract the thermodynamics and kinetics of folding and unfolding reactions. In hopping experiments, a molecule executes transitions between the unfolded and folded states at a preset value of the force [constant force mode (CFM) under force feedback] or trap position [passive mode (PM) without feedback] and the force-dependent kinetic rates extracted from the lifetime of each state (CFM) and the rupture force distributions (PM) using the Bell-Evans model. However, hopping experiments in the CFM are known to overestimate molecular distances and folding free energies for fast transitions compared to the response time of the feedback. In contrast, kinetic rate measurements from pulling experiments have been mostly done in the PM while the CFM is seldom implemented in pulling protocols. Here, we carry out hopping and pulling experiments in a short DNA hairpin in the PM and CFM at three different temperatures (6 °C, 25 °C, and 45 °C) exhibiting largely varying kinetic rates. As expected, we find that equilibrium hopping experiments in the CFM and PM perform well at 6 °C (where kinetics are slow), whereas the CFM overestimates molecular parameters at 45 °C (where kinetics are fast). In contrast, nonequilibrium pulling experiments perform well in both modes at all temperatures. This demonstrates that the same kind of feedback algorithm in the CFM leads to more reliable determination of the folding reaction parameters in irreversible pulling experiments.

Development and testing of novel bisphenol A-free adhesives for lingual fixed retainer bonding.

PubMed

Iliadi, Anna; Eliades, Theodore; Silikas, Nick; Eliades, George

2017-02-01

To comparatively evaluate the properties of two BPA-free experimental adhesives (EXA, EXB) for lingual fixed retainer bonding versus a commercially available reference material (Transbond LR-TLR) based on BPA-compound. The experimental materials were a flowable 60 per cent glass filler-filled UEDMA/TEGDMA flowable composite (EXB) and a 70 per cent glass filler-filled paste composite with PCDMA/UEDMA/TEGDMA co-monomers. The properties tested were degree of conversion (DC%), mechanical properties (Martens hardness-MH, elastic modulus-E IT , elastic index-n IT ), effect of prolonged (6 months) water storage (changes in Vickers microhardness-VHN) and pull-out strength employing a multi-stranded wire. EXB showed the highest DC% (63.6 per cent), followed by EXA (50.5 per cent) and TRL (44.1 per cent), with all means differences being statistically significant (P < 0.05). The statistical rankings of MH (MPa) and E IT (GPa) means were TLR (76.1MPa; 17.3GPa) > EXA (53MPa; 12.9GPa) > EXB (12.9MPa; 6.7GPa), whereas for n IT, EXB (40 per cent) > EXA (34.9 per cent), TLR (33.6 per cent). All materials were affected by prolonged water storage with significant differences among them in VHN. TLR was the most affected material (ΔVHN = -11 per cent), followed by EXA (ΔVHN = -6.8 per cent) and EXB (ΔVHN = -4.2 per cent). No statistically significant differences were found in the pull-out strength testing (24-24.2 N range) and failure mode (70-77 per cent mixed). Considering the differences between the two experimental materials, it may be concluded that the material containing the PCDMA/UEDMA/TEGDMA co-monomers may be used as an alternative to the control. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Are gender differences in upper-body power generated by elite cross-country skiers augmented by increasing the intensity of exercise?

PubMed

Hegge, Ann Magdalen; Myhre, Kenneth; Welde, Boye; Holmberg, Hans-Christer; Sandbakk, Øyvind

2015-01-01

In the current study, we evaluated the impact of exercise intensity on gender differences in upper-body poling among cross-country skiers, as well as the associated differences in aerobic capacity, maximal strength, body composition, technique and extent of training. Eight male and eight female elite skiers, gender-matched for level of performance by FIS points, carried out a 4-min submaximal, and a 3-min and 30-sec maximal all-out test of isolated upper-body double poling on a Concept2 ski ergometer. Maximal upper-body power and strength (1RM) were determined with a pull-down exercise. In addition, body composition was assessed with a DXA scan and training during the previous six months quantified from diaries. Relative to the corresponding female values (defined as 100%), the power output produced by the men was 88%, 95% and 108% higher during the submaximal, 3-min and 30-sec tests, respectively, and peak power in the pull-down strength exercise was 118% higher (all P<0.001). During the ergometer tests the work performed per cycle by the men was 97%, 102% and 91% greater, respectively, and the men elevated their cycle rate to a greater extent at higher intensities (both P<0.01). Furthermore, men had a 61% higher VO2peak, 58% higher 1RM, relatively larger upper-body mass (61% vs 56%) and reported considerably more upper-body strength and endurance training (all P<0.05). In conclusion, gender differences in upper-body power among cross-country skiers augmented as the intensity of exercise increased. The gender differences observed here are greater than those reported previously for both lower- and whole-body sports and coincided with greater peak aerobic capacity and maximal upper-body strength, relatively more muscle mass in the upper-body, and more extensive training of upper-body strength and endurance among the male skiers.

Are Gender Differences in Upper-Body Power Generated by Elite Cross-Country Skiers Augmented by Increasing the Intensity of Exercise?

PubMed Central

Hegge, Ann Magdalen; Myhre, Kenneth; Welde, Boye; Holmberg, Hans-Christer; Sandbakk, Øyvind

2015-01-01

In the current study, we evaluated the impact of exercise intensity on gender differences in upper-body poling among cross-country skiers, as well as the associated differences in aerobic capacity, maximal strength, body composition, technique and extent of training. Eight male and eight female elite skiers, gender-matched for level of performance by FIS points, carried out a 4-min submaximal, and a 3-min and 30-sec maximal all-out test of isolated upper-body double poling on a Concept2 ski ergometer. Maximal upper-body power and strength (1RM) were determined with a pull-down exercise. In addition, body composition was assessed with a DXA scan and training during the previous six months quantified from diaries. Relative to the corresponding female values (defined as 100%), the power output produced by the men was 88%, 95% and 108% higher during the submaximal, 3-min and 30-sec tests, respectively, and peak power in the pull-down strength exercise was 118% higher (all P<0.001). During the ergometer tests the work performed per cycle by the men was 97%, 102% and 91% greater, respectively, and the men elevated their cycle rate to a greater extent at higher intensities (both P<0.01). Furthermore, men had a 61% higher VO2peak, 58% higher 1RM, relatively larger upper-body mass (61% vs 56%) and reported considerably more upper-body strength and endurance training (all P<0.05). In conclusion, gender differences in upper-body power among cross-country skiers augmented as the intensity of exercise increased. The gender differences observed here are greater than those reported previously for both lower- and whole-body sports and coincided with greater peak aerobic capacity and maximal upper-body strength, relatively more muscle mass in the upper-body, and more extensive training of upper-body strength and endurance among the male skiers. PMID:26000713

The Tablecloth Trick, Take II.

ERIC Educational Resources Information Center

Ringlein, James

2003-01-01

Explores the basic physics behind pulling a tablecloth out from under a set of dishes, glassware, and utensils without disturbing them. Discusses terminology of Newton's laws of motion and illustrates them using three simple examples. (NB)

Design of DC-contact RF MEMS switch with temperature stability

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

Sun, Junfeng; Nanjing Electronic Devices Institute, Nanjing, 210016; Li, Zhiqun, E-mail: zhiqunli@seu.edu.cn

In order to improve the temperature stability of DC-contact RF MEMS switch, a thermal buckle-beam structure is implemented. The stability of the switch pull-in voltage versus temperature is not only improved, but also the impact of stress and stress gradient on the drive voltage is suppressed. Test results show that the switch pull-in voltage is less sensitive to temperature between -20 °C and 100 °C. The variable rate of pull-in voltage to temperature is about -120 mV/°C. The RF performance of the switch is stable, and the isolation is almost independent of temperature. After being annealed at 280 °C formore » 12 hours, our switch samples, which are suitable for packaging, have less than 1.5% change in the rate of pull-in voltage.« less

An approximate model for cancellous bone screw fixation.

PubMed

Brown, C J; Sinclair, R A; Day, A; Hess, B; Procter, P

2013-04-01

This paper presents a finite element (FE) model to identify parameters that affect the performance of an improved cancellous bone screw fixation technique, and hence potentially improve fracture treatment. In cancellous bone of low apparent density, it can be difficult to achieve adequate screw fixation and hence provide stable fracture fixation that enables bone healing. Data from predictive FE models indicate that cements can have a significant potential to improve screw holding power in cancellous bone. These FE models are used to demonstrate the key parameters that determine pull-out strength in a variety of screw, bone and cement set-ups, and to compare the effectiveness of different configurations. The paper concludes that significant advantages, up to an order of magnitude, in screw pull-out strength in cancellous bone might be gained by the appropriate use of a currently approved calcium phosphate cement.

Arthroscopic repair of the posterior horn of the medial meniscus with opening wedge high tibial osteotomy: surgical technique.

PubMed

Jung, Kwang Am; Kim, Sung Jae; Lee, Su Chan; Jeong, Jae Hoon; Song, Moon Bok; Lee, Choon Key

2009-07-01

Simultaneous repair of a radial tear at the tibial attachment site of the posterior horn of the medial meniscus under special circumstances requiring tibial valgus osteotomy is technically difficult. First, most patients who need an osteotomy have a narrowed medial tibiofemoral joint space. In such a situation, the pull-out suture technique is more difficult to perform than in a normal joint space. Second, pulling out suture strands that penetrate the posterior horn of the medial meniscus to the anterior tibial cortex increases the risk of transection during osteotomy. We performed a meniscus repair combined with an opening wedge tibial valgus osteotomy without complications and present our technique as a new method for use in selective cases necessitating both meniscus repair of a complete radial tear and opening wedge tibial osteotomy.

Comparative study of two precision overdenture attachment designs.

PubMed

Cohen, B I; Pagnillo, M; Condos, S; Deutsch, A S

1996-08-01

In this study two precision overdenture attachment designs were tested for retention--a nylon overdenture cap system and a new cap and keeper system. The new cap and keeper system was designed to reduce the time involved in replacing a cap worn by the conditions of the oral environment. Six groups were tested at two different angles and retentive failure was examined at two different angles (26 and 0 degrees). Failure was measured in pounds with a force gauge over a 2000 pull cycle. The amount of force required to remove caps for two overdenture caps and a replaced cap for the metal keeper system was determined. Two dependent variables were absolute force and relative force. Repeated measures analysis of variance (RMANOVA) was used to compare the between-subjects effects of cap and angle, and the within-subjects effect of pull. The results indicated a significant difference between cap types (p < 0.0001) with respect to the relative force required to remove the cap. There was no effect of angle. For absolute force, RMANOVA revealed a highly significant interaction between pull and cap (p < 0.0001). Thus, the way that force changed over pulls depended on which cap was used (no effect of angle). For relative force, RMANOVA revealed no interaction between pull and cap, but there was a main effect of cap type (p < 0.0001) (no effect of angle). The nylon cap design required less force for removal but showed more consistency in the force required over the course of the 2000 pulls when compared with the keeper with cap insert. The results obtained in this study were consistent with similar studies in literature.

Muscle Strength Endurance Testing Development Based Photo Transistor with Motion Sensor Ultrasonic

NASA Astrophysics Data System (ADS)

Rusdiana, A.

2017-03-01

The endurance of upper-body muscles is one of the most important physical fitness components. As technology develops, the process of test and assessment is now getting digital; for instance, there are a sensor stuck to the shoe (Foot Pod, Polar, and Sunto), Global Positioning System (GPS) and Differential Global Positioning System (DGPS), radar, photo finish, kinematic analysis, and photocells. Those devices aim to analyze the performances and fitness of athletes particularly the endurance of arm, chest, and shoulder muscles. In relation to that, this study attempt to create a software and a hardware for pull-ups through phototransistor with ultrasonic motion sensor. Components needed to develop this device consist of microcontroller MCS-51, photo transistor, light emitting diode, buzzer, ultrasonic sensor, and infrared sensor. The infrared sensor is put under the buffer while the ultrasonic sensor is stuck on the upper pole. The components are integrated with an LED or a laptop made using Visual Basic 12 software. The results show that pull-ups test using digital device (mean; 9.4 rep) is lower than using manual calculation (mean; 11.3 rep). This is due to the fact that digital test requires the test-takers to do pull-ups perfectly.

Theoretical modeling and experimental study of dielectric loss of the multi-push-pull mode magnetoelectric laminate composites

NASA Astrophysics Data System (ADS)

Xu, Bingbing; Ma, Jiashuai; Fang, Cong; Yao, Meng; Di, Wenning; Li, Xiaobing; Luo, Haosu

2018-02-01

In this work, we establish a dielectric loss model for multi-push-pull mode ME laminate composites. It deduces that the total dielectric loss of the ME composites equals the linear average of the dielectric loss of piezoelectric plate and epoxy resin. But further analysis of this model has indicated that we can ignore the dielectric loss of epoxy resin. To verify this model, we use three kinds of epoxy resin with different dielectric loss to fabricate multi-push-pull mode PMNT/Metglas ME laminate composites respectively. It turns out that the different kinds of epoxy resin have little influence on the total dielectric loss, capacitance and piezoelectricity of the composites, which demonstrates that our model conforms to the practical case. Therefore, we can pay more attention to the mechanical properties of epoxy resin rather than its dielectric loss on fabricating the ME laminate composites.

Endoscopic removal of a tablespoon lodged within the duodenum

PubMed Central

Watanabe, Takashi; Aoyagi, Kunihiko; Tomioka, Yoshitaka; Ishibashi, Hideki; Sakisaka, Shotaro

2015-01-01

Here we report the case of a 34-year-old man who underwent endoscopic removal of a tablespoon from the stomach that was lodged within the duodenum. Removal required the use of a two-channel upper endoscope and polypectomy snares. Using the double-snare technique, the spoon was grasped at the proximal and distal parts of the handle. The double-snare was first pulled unsuccessfully and then pulled with simultaneous manual abdominal compression of the bulbus from the body surface. Compression was gently applied towards the stomach. As a result, the head of the spoon prolapsed from the bulbus, and was easily retracted from the stomach without any complications. In cases of foreign body lodging within the duodenum, the manual abdominal compression technique may help clinicians pull out the object and avoid surgery. The usefulness of manual compression is dependent on the foreign body’s sharpness and the location. PMID:25945026

Damage Accumulation in Cyclically-Loaded Glass-Ceramic Matrix Composites Monitored by Acoustic Emission

PubMed Central

Aggelis, D. G.; Dassios, K. G.; Kordatos, E. Z.; Matikas, T. E.

2013-01-01

Barium osumilite (BMAS) ceramic matrix composites reinforced with SiC-Tyranno fibers are tested in a cyclic loading protocol. Broadband acoustic emission (AE) sensors are used for monitoring the occurrence of different possible damage mechanisms. Improved use of AE indices is proposed by excluding low-severity signals based on waveform parameters, rather than only threshold criteria. The application of such improvements enhances the accuracy of the indices as accumulated damage descriptors. RA-value, duration, and signal energy follow the extension cycles indicating moments of maximum or minimum strain, while the frequency content of the AE signals proves very sensitive to the pull-out mechanism. PMID:24381524

Development of a miniaturized hour-glass shaped fatigue specimen

NASA Astrophysics Data System (ADS)

Miwa, Y.; Jitsukawa, S.; Hishinuma, A.

1998-10-01

Diametral strain-controlled push-pull fatigue tests with zero mean strain were carried out with miniaturized hour-glass shaped specimens of an austenitic stainless steel in solution annealed condition at room temperature. The specimens had a diameter of 1.25 mm at the minimum cross section and a total length of 25.4 mm. The number of cycles to failure ( Nf) was equal to or slightly greater than that obtained with standard size specimens. Nf was also revealed to be rather insensitive to the specimen load axis offset, indicating that the requirement of the specimen alignment to the load axis was not very severe for the miniaturized specimen.

Domestication has not affected the understanding of means-end connections in dogs

PubMed Central

Range, Friederike; Möslinger, Helene; Virányi, Zs

2015-01-01

Recent studies have revealed that dogs often perform well in cognitive tasks in the social domain, but rather poorly in the physical domain. This dichotomy has led to the hypothesis that the domestication process might have enhanced the social cognitive skills of dogs (Hare et al. in Science 298:1634–1636, 2002; Miklósi et al. in Curr Biol 13:763–766, 2003) but at the same time had a detrimental effect on their physical cognition (Frank in Z Tierpsychol 5:389–399, 1980). Despite the recent interest in dog cognition and especially the effects of domestication, the latter hypothesis has hardly been tested and we lack detailed knowledge of the physical understanding of wolves in comparison with dogs. Here, we set out to examine whether adult wolves and dogs rely on means-end connections using the string-pulling task, to test the prediction that wolves would perform better than dogs in such a task of physical cognition. We found that at the group level, dogs were more prone to commit the proximity error, while the wolves showed a stronger side bias. Neither wolves nor dogs showed an instantaneous understanding of means-end connection, but made different mistakes. Thus, the performance of the wolves and dogs in this string-pulling task did not confirm that domestication has affected the physical cognition of dogs. PMID:22460629

Domestication has not affected the understanding of means-end connections in dogs.

PubMed

Range, Friederike; Möslinger, Helene; Virányi, Zs

2012-07-01

Recent studies have revealed that dogs often perform well in cognitive tasks in the social domain, but rather poorly in the physical domain. This dichotomy has led to the hypothesis that the domestication process might have enhanced the social cognitive skills of dogs (Hare et al. in Science 298:1634-1636, 2002; Miklósi et al. in Curr Biol 13:763-766, 2003) but at the same time had a detrimental effect on their physical cognition (Frank in Z Tierpsychol 5:389-399, 1980). Despite the recent interest in dog cognition and especially the effects of domestication, the latter hypothesis has hardly been tested and we lack detailed knowledge of the physical understanding of wolves in comparison with dogs. Here, we set out to examine whether adult wolves and dogs rely on means-end connections using the string-pulling task, to test the prediction that wolves would perform better than dogs in such a task of physical cognition. We found that at the group level, dogs were more prone to commit the proximity error, while the wolves showed a stronger side bias. Neither wolves nor dogs showed an instantaneous understanding of means-end connection, but made different mistakes. Thus, the performance of the wolves and dogs in this string-pulling task did not confirm that domestication has affected the physical cognition of dogs.

49 CFR 572.125 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... of the dummy, the pull cable, and the load cell as shown in Figure N5. (7) Apply a tension force in the midsagittal plane to the pull cable as shown in Figure N5 at any upper torso deflection rate... determine the stiffness effects of the lumbar spine (drawing 127-3002), including cable (drawing 127-8095...

On optimal control problem for conservation law modelling one class of highly re-entrant production systems

NASA Astrophysics Data System (ADS)

D'Apice, Ciro; Kogut, Peter I.

2017-07-01

We discuss the optimal control problem stated as the minimization in the L2-sense of the mismatch between the actual out-flux and a demand forecast for a hyperbolic conservation law that models a highly re-entrant production system. The output of the factory is described as a function of the work in progress and the position of the so-called push-pull point (PPP) where we separate the beginning of the factory employing a push policy from the end of the factory, which uses a pull policy.

How Does a Hopping Kangaroo Breathe?

ERIC Educational Resources Information Center

Giuliodori, Mauricio J.; Lujan, Heidi L.; Janbaih, Hussein; DiCarlo, Stephen E.

2010-01-01

We developed a model to demonstrate how a hopping kangaroo breathes. Interestingly, a kangaroo uses less energy to breathe while hopping than while standing still. This occurs, in part, because rather than using muscle power to move air into and out of the lungs, air is pulled into (inspiration) and pushed out of (expiration) the lungs as the…

Compensatory Education Product Evaluation: Elementary and Secondary Programs 1991-1992.

ERIC Educational Resources Information Center

Saginaw Public Schools, MI. Dept. of Evaluation Services.

An evaluation was done of compensatory educational programs in reading and mathematics in the Saginaw (Michigan) School District. The elementary Compensatory Education (CE) program is both a push-in format (grades 1 and 2) and a pull-out format (periodically taking students out of regular classrooms) that serves 2,045 students in grades 1 through…

Small-scale field evaluation of push-pull system against early- and outdoor-biting malaria mosquitoes in an area of high pyrethroid resistance in Tanzania

PubMed Central

Mmbando, Arnold S.; Ngowo, Halfan S.; Kilalangongono, Masoud; Abbas, Said; Matowo, Nancy S.; Moore, Sarah J.; Okumu, Fredros O.

2017-01-01

Background: Despite high coverage of indoor interventions like insecticide-treated nets, mosquito-borne infections persist, partly because of outdoor-biting, early-biting and insecticide-resistant vectors. Push-pull systems, where mosquitoes are repelled from humans and attracted to nearby lethal targets, may constitute effective complementary interventions. Methods: A partially randomized cross-over design was used to test efficacy of push-pull in four experimental huts and four local houses, in an area with high pyrethroid resistance in Tanzania. The push-pull system consisted of 1.1% or 2.2% w/v transfluthrin repellent dispensers and an outdoor lure-and-kill device (odour-baited mosquito landing box). Matching controls were set up without push-pull. Adult male volunteers collected mosquitoes attempting to bite them outdoors, but collections were also done indoors using exit traps in experimental huts and by volunteers in the local houses. The collections were done hourly (1830hrs-0730hrs) and mosquito catches compared between push-pull and controls. An. gambiae s.l. and An. funestus s.l. were assessed by PCR to identify sibling species, and ELISA to detect Plasmodium falciparum and blood meal sources. Results: Push-pull in experimental huts reduced outdoor-biting for An. arabiensis and Mansonia species by 30% and 41.5% respectively. However, the reductions were marginal and insignificant for An. funestus (12.2%; p>0.05) and Culex (5%; p>0.05). Highest protection against all species occurred before 2200hrs. There was no significant difference in number of mosquitoes inside exit traps in huts with or without push-pull. In local households, push-pull significantly reduced indoor and outdoor-biting of An. arabiensis by 48% and 25% respectively, but had no effect on other species. Conclusion: This push-pull system offered modest protection against outdoor-biting An. arabiensis, without increasing indoor mosquito densities. Additional experimentation is required to assess how transfluthrin-based products affect mosquito blood-feeding and mortality in push-pull contexts. This approach, if optimised, could potentially complement existing malaria interventions even in areas with high pyrethroid resistance. PMID:29568808

Workers in the VAB test SRB cables on STS-98 solid rocket boosters

NASA Technical Reports Server (NTRS)

2001-01-01

KENNEDY SPACE CENTER, Fla. -- In the Vehicle Assembly Building, United Space Alliance SRB technician Frank Meyer pulls cables out of the solid rocket booster system tunnel. Cable end covers are in a box near his feet. The SRB is part of Space Shuttle Atlantis, rolled back from Launch Pad 39A in order to conduct tests on the cables. A prior extensive evaluation of NASA'''s SRB cable inventory on the shelf revealed conductor damage in four (of about 200) cables. Shuttle managers decided to prove the integrity of the system tunnel cables already on Atlantis before launching. Workers are conducting inspections, making continuity checks and conducting X-ray analysis on the cables. The launch has been rescheduled no earlier than Feb. 6.

Inclined Fiber Pullout from a Cementitious Matrix: A Numerical Study

PubMed Central

Zhang, Hui; Yu, Rena C.

2016-01-01

It is well known that fibers improve the performance of cementitious composites by acting as bridging ligaments in cracks. Such bridging behavior is often studied through fiber pullout tests. The relation between the pullout force vs. slip end displacement is characteristic of the fiber-matrix interface. However, such a relation varies significantly with the fiber inclination angle. In the current work, we establish a numerical model to simulate the entire pullout process by explicitly representing the fiber, matrix and the interface for arbitrary fiber orientations. Cohesive elements endorsed with mixed-mode fracture capacities are implemented to represent the bond-slip behavior at the interface. Contact elements with Coulomb’s friction are placed at the interface to simulate frictional contact. The bond-slip behavior is first calibrated through pull-out curves for fibers aligned with the loading direction, then validated against experimental results for steel fibers oriented at 30∘ and 60∘. Parametric studies are then performed to explore the influences of both material properties (fiber yield strength, matrix tensile strength, interfacial bond) and geometric factors (fiber diameter, embedment length and inclination angle) on the overall pullout behavior, in particular on the maximum pullout load. The proposed methodology provides the necessary pull-out curves for a fiber oriented at a given angle for multi-scale models to study fracture in fiber-reinforced cementitious materials. The novelty lies in its capacity to capture the entire pullout process for a fiber with an arbitrary inclination angle. PMID:28773921

Inclined Fiber Pullout from a Cementitious Matrix: A Numerical Study.

PubMed

Zhang, Hui; Yu, Rena C

2016-09-26

It is well known that fibers improve the performance of cementitious composites by acting as bridging ligaments in cracks. Such bridging behavior is often studied through fiber pullout tests. The relation between the pullout force vs. slip end displacement is characteristic of the fiber-matrix interface. However, such a relation varies significantly with the fiber inclination angle. In the current work, we establish a numerical model to simulate the entire pullout process by explicitly representing the fiber, matrix and the interface for arbitrary fiber orientations. Cohesive elements endorsed with mixed-mode fracture capacities are implemented to represent the bond-slip behavior at the interface. Contact elements with Coulomb's friction are placed at the interface to simulate frictional contact. The bond-slip behavior is first calibrated through pull-out curves for fibers aligned with the loading direction, then validated against experimental results for steel fibers oriented at 30 ∘ and 60 ∘ . Parametric studies are then performed to explore the influences of both material properties (fiber yield strength, matrix tensile strength, interfacial bond) and geometric factors (fiber diameter, embedment length and inclination angle) on the overall pullout behavior, in particular on the maximum pullout load. The proposed methodology provides the necessary pull-out curves for a fiber oriented at a given angle for multi-scale models to study fracture in fiber-reinforced cementitious materials. The novelty lies in its capacity to capture the entire pullout process for a fiber with an arbitrary inclination angle.

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

Chen, L.; McGruer, N. E.; Adams, G. G.

We report the observation of two distinct modes of rate-dependent behavior during contact cycling tests. One is a higher pull-off force at low cycling rates and the other is a higher pull-off force at high cycling rates. Subsequent investigation of these contacts using scanning electron microscopy (SEM) demonstrates that these two rate-dependent modes can be related to brittle and ductile separation modes. The former behavior is indicative of brittle separation, whereas the latter accompanies ductile separation. Thus by monitoring the rate dependence of the pull-off force, the type of separation mode can be identified during cycling without interrupting the testmore » to perform SEM.« less

Confinement-Dependent Friction in Peptide Bundles

PubMed Central

Erbaş, Aykut; Netz, Roland R.

2013-01-01

Friction within globular proteins or between adhering macromolecules crucially determines the kinetics of protein folding, the formation, and the relaxation of self-assembled molecular systems. One fundamental question is how these friction effects depend on the local environment and in particular on the presence of water. In this model study, we use fully atomistic MD simulations with explicit water to obtain friction forces as a single polyglycine peptide chain is pulled out of a bundle of k adhering parallel polyglycine peptide chains. The whole system is periodically replicated along the peptide axes, so a stationary state at prescribed mean sliding velocity V is achieved. The aggregation number is varied between k = 2 (two peptide chains adhering to each other with plenty of water present at the adhesion sites) and k = 7 (one peptide chain pulled out from a close-packed cylindrical array of six neighboring peptide chains with no water inside the bundle). The friction coefficient per hydrogen bond, extrapolated to the viscous limit of vanishing pulling velocity V → 0, exhibits an increase by five orders of magnitude when going from k = 2 to k = 7. This dramatic confinement-induced friction enhancement we argue to be due to a combination of water depletion and increased hydrogen-bond cooperativity. PMID:23528088

The biomechanical strength of a hardware-free femoral press-fit method for ACL bone-tendon-bone graft fixation.

PubMed

Arnold, M P; Burger, L D; Wirz, D; Goepfert, B; Hirschmann, M T

2017-04-01

The purpose was to investigate graft slippage and ultimate load to failure of a femoral press-fit fixation technique for anterior cruciate ligament (ACL) reconstruction. Nine fresh-frozen knees were used. Standardized harvesting of the B-PT-B graft was performed. The femora were cemented into steel rods, and a tunnel was drilled outside-in into the native ACL footprint and expanded using a manual mill bit. The femoral bone block was fixed press-fit. To pull the free end of the graft, it was fixed to a mechanical testing machine using a deep-freezing technique. A motion capture system was used to assess three-dimensional micro-motion. After preconditioning of the graft, 1000 cycles of tensile loading were applied. Finally, an ultimate load to failure test was performed. Graft slippage in mm ultimate load to failure as well as type of failure was noted. In six of the nine measured specimens, a typical pattern of graft slippage was observed during cyclic loading. For technical reasons, the results of three knees had to be discarded. 78.6 % of total graft slippage occurred in the first 100 cycles. Once the block had settled, graft slippage converged to zero, highlighting the importance of initial preconditioning of the graft in the clinical setting. Graft slippage after 1000 cycles varied around 3.4 ± 3.2 mm (R = 1.3-9.8 mm) between the specimens. Ultimate loading (n = 9) revealed two characteristic patterns of failure. In four knees, the tendon ruptured, while in five knees the bone block was pulled out of the femoral tunnel. The median ultimate load to failure was 852 N (R = 448-1349 N). The implant-free femoral press-fit fixation provided adequate primary stability with ultimate load to failure pull forces at least equal to published results for interference screws; hence, its clinical application is shown to be safe.

New devices for measuring forces on the kayak foot bar and on the seat during flat-water kayak paddling: a technical report.

PubMed

Nilsson, Johnny E; Rosdahl, Hans G

2014-03-01

The purpose was to develop and validate portable force-measurement devices for recording push and pull forces applied by each foot to the foot bar of a kayak and the horizontal force at the seat. A foot plate on a single-point force transducer mounted on the kayak foot bar underneath each foot allowed the push and pull forces to be recorded. Two metal frames interconnected with 4 linear ball bearings, and a force transducer allowed recording of horizontal seat force. The foot-bar-force device was calibrated by loading each foot plate with weights in the push-pull direction perpendicular to the foot plate surface, while the seat-force device was calibrated to horizontal forces with and without weights on the seat. A strong linearity (r2 = .99-1.0) was found between transducer output signal and load force in the push and pull directions for both foot-bar transducers perpendicular to the foot plate and the seat-force-measuring device. Reliability of both devices was tested by means of a test-retest design. The coefficient of variation (CV) for foot-bar push and pull forces ranged from 0.1% to 1.1%, and the CV for the seat forces varied from 0.6% to 2.2%. The current study opens up a field for new investigations of the forces generated in the kayak and ways to optimize kayak-paddling performance.

Effects of myofascial release leg pull and sagittal plane isometric contract-relax techniques on passive straight-leg raise angle.

PubMed

Hanten, W P; Chandler, S D

1994-09-01

Experimental evidence does not currently exist to support the claims of clinical effectiveness for myofascial release techniques. This presents an obvious need to document the effects of myofascial release. The purpose of this study was to compare the effects of two techniques, sagittal plane isometric contract-relax and myofascial release leg pull for increasing hip flexion range of motion (ROM) as measured by the angle of passive straight-leg raise. Seventy-five nondisabled, female subjects 18-29 years of age were randomly assigned to contract-relax, leg pull, or control groups. Pretest hip flexion ROM was measured for each subject's right hip with a passive straight-leg raise test using a fluid-filled goniometer. Subjects in the treatment groups received either contract-relax or leg pull treatment applied to the right lower extremity; subjects in the control group remained supine quietly for 5 minutes. Following treatment, posttest straight-leg raise measurements were performed. A one-way analysis of variance followed by a Newman-Keuls post hoc comparison of mean gain scores showed that subjects receiving contract-relax treatment increased their ROM significantly more than those who received leg pull treatment, and the increase in ROM of subjects in both treatment groups was significantly higher than those of the control group. The results suggest that while both contract-relax and leg pull techniques can significantly increase hip flexion ROM in normal subjects, contract-relax treatment may be more effective and efficient than leg pull treatment.

Characterization of power induced heating and damage in fiber optic probes for near-field scanning optical microscopy

NASA Astrophysics Data System (ADS)

Dickenson, Nicholas E.; Erickson, Elizabeth S.; Mooren, Olivia L.; Dunn, Robert C.

2007-05-01

Tip-induced sample heating in near-field scanning optical microscopy (NSOM) is studied for fiber optic probes fabricated using the chemical etching technique. To characterize sample heating from etched NSOM probes, the spectra of a thermochromic polymer sample are measured as a function of probe output power, as was previously reported for pulled NSOM probes. The results reveal that sample heating increases rapidly to ˜55-60°C as output powers reach ˜50nW. At higher output powers, the sample heating remains approximately constant up to the maximum power studied of ˜450nW. The sample heating profiles measured for etched NSOM probes are consistent with those previously measured for NSOM probes fabricated using the pulling method. At high powers, both pulled and etched NSOM probes fail as the aluminum coating is damaged. For probes fabricated in our laboratory we find failure occurring at input powers of 3.4±1.7 and 20.7±6.9mW for pulled and etched probes, respectively. The larger half-cone angle for etched probes (˜15° for etched and ˜6° for pulled probes) enables more light delivery and also apparently leads to a different failure mechanism. For pulled NSOM probes, high resolution images of NSOM probes as power is increased reveal the development of stress fractures in the coating at a taper diameter of ˜6μm. These stress fractures, arising from the differential heating expansion of the dielectric and the metal coating, eventually lead to coating removal and probe failure. For etched tips, the absence of clear stress fractures and the pooled morphology of the damaged aluminum coating following failure suggest that thermal damage may cause coating failure, although other mechanisms cannot be ruled out.

Characterization of power induced heating and damage in fiber optic probes for near-field scanning optical microscopy.

PubMed

Dickenson, Nicholas E; Erickson, Elizabeth S; Mooren, Olivia L; Dunn, Robert C

2007-05-01

Tip-induced sample heating in near-field scanning optical microscopy (NSOM) is studied for fiber optic probes fabricated using the chemical etching technique. To characterize sample heating from etched NSOM probes, the spectra of a thermochromic polymer sample are measured as a function of probe output power, as was previously reported for pulled NSOM probes. The results reveal that sample heating increases rapidly to approximately 55-60 degrees C as output powers reach approximately 50 nW. At higher output powers, the sample heating remains approximately constant up to the maximum power studied of approximately 450 nW. The sample heating profiles measured for etched NSOM probes are consistent with those previously measured for NSOM probes fabricated using the pulling method. At high powers, both pulled and etched NSOM probes fail as the aluminum coating is damaged. For probes fabricated in our laboratory we find failure occurring at input powers of 3.4+/-1.7 and 20.7+/-6.9 mW for pulled and etched probes, respectively. The larger half-cone angle for etched probes ( approximately 15 degrees for etched and approximately 6 degrees for pulled probes) enables more light delivery and also apparently leads to a different failure mechanism. For pulled NSOM probes, high resolution images of NSOM probes as power is increased reveal the development of stress fractures in the coating at a taper diameter of approximately 6 microm. These stress fractures, arising from the differential heating expansion of the dielectric and the metal coating, eventually lead to coating removal and probe failure. For etched tips, the absence of clear stress fractures and the pooled morphology of the damaged aluminum coating following failure suggest that thermal damage may cause coating failure, although other mechanisms cannot be ruled out.

Wound care centers

MedlinePlus

... treatment, you sit inside a special chamber. The air pressure inside the chamber is about two and a half times greater than the normal pressure in the atmosphere. This pressure helps ... -- pulling the air out of a closed dressing, creating a vacuum. ...

Understanding Your Water Bill

EPA Pesticide Factsheets

An easy to way to understand individual water use is to look at your water bill—not just the amount due, but how much water you used. Pull out your water bill and follow our steps to learn more about it.

Investigating the Human Skeleton.

ERIC Educational Resources Information Center

Slesnick, Irwin L.

1982-01-01

Instructions are provided for assembly of a pull-out, two-sided picture puzzle of the skeleton of a seven-year-old girl. Suggestions for activities using the assembled puzzle and comments on bones and bone morphology are also provided. (Author/JN)

Vascular anatomy of the stomach related to resection procedures strategy.

PubMed

Prudius, V; Procházka, V; Pavlovský, Z; Prudius, D; Kala, Z

2017-04-01

This study is focused on the vascular anatomy of the stomach in relation to the gastric pull-up construction. The vascular anatomy was studied on forty-one human specimens. We find out the differences in blood supplement between anterior and posterior wall. It was maked an review of the main trunk arteries of the stomach. To display the vessels of the stomach we used diaphanoscopy, digital shooting in special mode and micro preparation of the vessels. We find out that left gastric artery gives more branches to the posterior wall and right gastroepiploic artery (RGEA) gives more branches to the anterior wall. But brunches of RGEA are longer on the posterior wall than on the anterior. Also we are offering the new classification of the RGEA related to gastric pull-up construction. This classification based not only on the anatomical shapes of RGEA but on the properties of the flow dynamics through the artery.

Development of Active DNA Control Technique for DNA Sequencer With a Solid-state Nanopore

NASA Astrophysics Data System (ADS)

Akahori, Rena; Harada, Kunio; Goto, Yusuke; Yanagi, Itaru; Yokoi, Takahide; Oura, Takeshi; Shibahara, Masashi; Takeda, Ken-Ichi

We have developed a technique that can control the arbitrary speeds of DNA passing through a solid-state nanopore of a DNA sequencer. For this active DNA control technique, we used a DNA-immobilized Si probe, larger than the membrane with a nanopore, and used a piezoelectric actuator and stepper motor to drive the probe. This probe enables a user to adjust the relative position between the nanopore and DNA immobilized on the probe without the need for precise lateral control. In this presentation, we demonstrate how DNA (block copolymer ([(dT)25-(dC)25-(dA)50]m)), immobilized on the probe, slid through a nanopore and was pulled out using the active DNA control technique. As the DNA-immobilized probe was being pulled out, we obtained various ion-current signal levels corresponding to the number of different nucleotides in a single strand of DNA.

Introduction of steered molecular dynamics into UNRES coarse-grained simulations package.

PubMed

Sieradzan, Adam K; Jakubowski, Rafał

2017-03-30

In this article, an implementation of steered molecular dynamics (SMD) in coarse-grain UNited RESidue (UNRES) simulations package is presented. Two variants of SMD have been implemented: with a constant force and a constant velocity. The huge advantage of SMD implementation in the UNRES force field is that it allows to pull with the speed significantly lower than the accessible pulling speed in simulations with all-atom representation of a system, with respect to a reasonable computational time. Therefore, obtaining pulling speed closer to those which appear in the atomic force spectroscopy is possible. The newly implemented method has been tested for behavior in a microcanonical run to verify the influence of introduction of artificial constrains on keeping total energy of the system. Moreover, as time dependent artificial force was introduced, the thermostat behavior was tested. The new method was also tested via unfolding of the Fn3 domain of human contactin 1 protein and the I27 titin domain. Obtained results were compared with Gø-like force field, all-atom force field, and experimental results. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Strength tests for elite rowers: low- or high-repetition?

PubMed

Lawton, Trent W; Cronin, John B; McGuigan, Michael R

2014-01-01

The purpose of this project was to evaluate the utility of low- and high-repetition maximum (RM) strength tests used to assess rowers. Twenty elite heavyweight males (age 23.7 ± 4.0 years) performed four tests (5 RM, 30 RM, 60 RM and 120 RM) using leg press and seated arm pulling exercise on a dynamometer. Each test was repeated on two further occasions; 3 and 7 days from the initial trial. Per cent typical error (within-participant variation) and intraclass correlation coefficients (ICCs) were calculated using log-transformed repeated-measures data. High-repetition tests (30 RM, 60 RM and 120 RM), involving seated arm pulling exercise are not recommended to be included in an assessment battery, as they had unsatisfactory measurement precision (per cent typical error > 5% or ICC < 0.9). Conversely, low-repetition tests (5 RM) involving leg press and seated arm pulling exercises could be used to assess elite rowers (per cent typical error ≤ 5% and ICC ≥ 0.9); however, only 5 RM leg pressing met criteria (per cent typical error = 2.7%, ICC = 0.98) for research involving small samples (n = 20). In summary, low-repetition 5 RM strength testing offers greater utility as assessments of rowers, as they can be used to measure upper- and lower-body strength; however, only the leg press exercise is recommended for research involving small squads of elite rowers.

Measuring the Strength of the Horned Passalus Beetle, Odontotaenius disjunctus: Revisiting an Old Topic with Modern Technology

PubMed Central

Davis, Andrew K.; Attarha, Barrett; Piefke, Taylor J.

2013-01-01

Over a century ago, a pioneering researcher cleverly devised a means to measure how much weight the horned passalus beetle, Odontotaenius disjunctus (Illiger) (Coleoptera: Passalidae), could pull using a series of springs, pulleys, and careful observation. The technology available in modern times now allows for more rigorous data collection on this topic, which could have a number of uses in scientific investigations. In this study, an apparatus was constructed using a dynamometer and a data logger in an effort to ascertain the pulling strength of this species. By allowing beetles to pull for 10 min, each beetle's mean and maximum pulling force (in Newtons) were obtained for analyses, and whether these measures are related was determined. Then, whether factors such as body length, thorax size, horn size, or gender affect either measure of strength was investigated. Basic body measurements, including horn size, of males versus females were compared. The measurements of 38 beetles (20 females, 18 males) showed there was no difference in overall body length between sexes, but females had greater girth (thorax width) than males, which could translate into larger muscle mass. A total of 21 beetles (10 females, 11 males) were tested for pulling strength. The grand mean pulling force was 0.14 N, and the grand mean maximum was 0.78 N. Despite the fact that beetles tended to pull at 20% of their maximum capacity most of the time, and that maximum force was over 5 times larger than the mean force, the 2 measures were highly correlated, suggesting they may be interchangeable for research purposes. Females had twice the pulling strength (both maximum and mean force) as males in this species overall, but when the larger thorax size of females was considered, the effect of gender was not significant. Beetle length was not a significant predictor of pulling force, but horn size was associated with maximum force. The best predictor of both measures of strength appeared to be thorax size. There are a multitude of interesting scientific questions that could be addressed using data on beetle pulling strength, and this project serves as a starting point for such work. PMID:24735074

Containerless glass fiber processing

NASA Technical Reports Server (NTRS)

Ethridge, E. C.; Naumann, R. J.

1986-01-01

An acoustic levitation furnace system is described that was developed for testing the feasibility of containerless fiber pulling experiments. It is possible to levitate very dense materials such as platinum at room temperature. Levitation at elevated temperatures is much more difficult. Samples of dense heavy metal fluoride glass were levitated at 300 C. It is therefore possible that containerless fiber pulling experiments could be performed. Fiber pulling from the melt at 650 C is not possible at unit gravity but could be possible at reduced gravities. The Acoustic Levitation Furnace is described, including engineering parameters and processing information. It is illustrated that a shaped reflector greatly increases the levitation force aiding the levitation of more dense materials.

Scoliosis corrective force estimation from the implanted rod deformation using 3D-FEM analysis.

PubMed

Abe, Yuichiro; Ito, Manabu; Abumi, Kuniyoshi; Sudo, Hideki; Salmingo, Remel; Tadano, Shigeru

2015-01-01

Improvement of material property in spinal instrumentation has brought better deformity correction in scoliosis surgery in recent years. The increase of mechanical strength in instruments directly means the increase of force, which acts on bone-implant interface during scoliosis surgery. However, the actual correction force during the correction maneuver and safety margin of pull out force on each screw were not well known. In the present study, estimated corrective forces and pull out forces were analyzed using a novel method based on Finite Element Analysis (FEA). Twenty adolescent idiopathic scoliosis patients (1 boy and 19 girls) who underwent reconstructive scoliosis surgery between June 2009 and Jun 2011 were included in this study. Scoliosis correction was performed with 6mm diameter titanium rod (Ti6Al7Nb) using the simultaneous double rod rotation technique (SDRRT) in all cases. The pre-maneuver and post-maneuver rod geometry was collected from intraoperative tracing and postoperative 3D-CT images, and 3D-FEA was performed with ANSYS. Cobb angle of major curve, correction rate and thoracic kyphosis were measured on X-ray images. Average age at surgery was 14.8, and average fusion length was 8.9 segments. Major curve was corrected from 63.1 to 18.1 degrees in average and correction rate was 71.4%. Rod geometry showed significant change on the concave side. Curvature of the rod on concave and convex sides decreased from 33.6 to 17.8 degrees, and from 25.9 to 23.8 degrees, respectively. Estimated pull out forces at apical vertebrae were 160.0N in the concave side screw and 35.6N in the convex side screw. Estimated push in force at LIV and UIV were 305.1N in the concave side screw and 86.4N in the convex side screw. Corrective force during scoliosis surgery was demonstrated to be about four times greater in the concave side than in convex side. Averaged pull out and push in force fell below previously reported safety margin. Therefore, the SDRRT maneuver was safe for correcting moderate magnitude curves. To prevent implant breakage or pedicle fracture during the maneuver in a severe curve correction, mobilization of spinal segment by releasing soft tissue or facet joint could be more important than using a stronger correction maneuver with a rigid implant.

The pull of the past: when do habits persist despite conflict with motives?

PubMed

Neal, David T; Wood, Wendy; Wu, Mengju; Kurlander, David

2011-11-01

To identify the factors that disrupt and maintain habit performance, two field experiments tested the conditions under which people eat out of habit, leading them to resist motivational influences. Habitual popcorn eaters at a cinema were minimally influenced by their hunger or how much they liked the food, and they ate equal amounts of stale and fresh popcorn. Yet, mechanisms of automaticity influenced habit performance: Participants ate out of habit, regardless of freshness, only when currently in the context associated with past performance (i.e., a cinema; Study 1) and only when eating in a way that allowed them to automatically execute the response cued by that context (i.e., eating with their dominant hand; Study 2). Across all conditions, participants with weaker cinema-popcorn-eating habits ate because of motivations such as liking for the popcorn. The findings reveal how habits resist conflicting motives and provide insight into promising mechanisms of habit change.

Optimal packing size of non-ligated CdSe nanoclusters for microstructure synthesis

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

Tefera, Anteneh G.; Mochena, Mogus D.; Johnson, Elijah

2014-09-14

Structural and electrostatic properties of nanoclusters of CdSe of diameter 1–2 nm are studied with first principle calculations to determine the optimal size for synthesizing microstructures. Based on robustness of the core structure, i.e., the retention of tetrahedral geometry, hexagonal ring structure, and overall wu{sup ¨}rtzite structure to surface relaxations, we conclude that nanoclusters of ~2 nm diameter are the best candidates to form a dense microstructure with minimal interstitial space. Se-terminated surfaces retain a zigzag structure as Se atoms are pulled out and Cd atoms are pulled in due to relaxation, therefore, are best suited for inter-nanocluster formations.

Fiber pulling apparatus modification

NASA Technical Reports Server (NTRS)

Smith, Guy A.; Workman, Gary L.

1992-01-01

A reduced gravity fiber pulling apparatus (FPA) was constructed in order to study the effects of gravity on glass fiber formation. The apparatus was specifically designed and built for use on NASA's KC-135 aircraft. Four flights have been completed to date during which E-glass fiber was successfully produced in simulated zero, high, and lunar gravity environments. In addition simulated lunar soil samples were tested for their fiber producing properties using the FPA.

Shipboard Coatings Developments, and Emerging Surface Technologies

DTIC Science & Technology

2009-09-01

ALGAE GROWTH. Other pulls not recorded, no complaints to NAVSEA about speed. April 2008 Pulled for engine work, cleaned well, may have been over-coated...BATELLE TEST SITE, 58 MONTH, FULL IMMERSION RESULTS PRESSURE WASH, ALGAE EASILY REMOVED, POLISHING APPARENT. SOME HARD FOULING ON WELDS, NOT A...by ~500 mV • Protection potential increased by ~1000mV * Short-term EOC does not take into account seawater biofilm corrosion potential ennoblement

Design of a haptic device with grasp and push-pull force feedback for a master-slave surgical robot.

PubMed

Hu, Zhenkai; Yoon, Chae-Hyun; Park, Samuel Byeongjun; Jo, Yung-Ho

2016-07-01

We propose a portable haptic device providing grasp (kinesthetic) and push-pull (cutaneous) sensations for optical-motion-capture master interfaces. Although optical-motion-capture master interfaces for surgical robot systems can overcome the stiffness, friction, and coupling problems of mechanical master interfaces, it is difficult to add haptic feedback to an optical-motion-capture master interface without constraining the free motion of the operator's hands. Therefore, we utilized a Bowden cable-driven mechanism to provide the grasp and push-pull sensation while retaining the free hand motion of the optical-motion capture master interface. To evaluate the haptic device, we construct a 2-DOF force sensing/force feedback system. We compare the sensed force and the reproduced force of the haptic device. Finally, a needle insertion test was done to evaluate the performance of the haptic interface in the master-slave system. The results demonstrate that both the grasp force feedback and the push-pull force feedback provided by the haptic interface closely matched with the sensed forces of the slave robot. We successfully apply our haptic interface in the optical-motion-capture master-slave system. The results of the needle insertion test showed that our haptic feedback can provide more safety than merely visual observation. We develop a suitable haptic device to produce both kinesthetic grasp force feedback and cutaneous push-pull force feedback. Our future research will include further objective performance evaluations of the optical-motion-capture master-slave robot system with our haptic interface in surgical scenarios.

Performance evaluation and specification of trackless tack : [project summary].

DOT National Transportation Integrated Search

2016-09-01

Researchers compared two tracking resistance tests for tack: a track-free time test and a modified dynamic shear rheometer (DSR) tackiness test. : Researchers compared four bond strength tests: interface shear, pull-off, torque, and Arcan. Then, usin...

Friction plug welding

NASA Technical Reports Server (NTRS)

Takeshita, Riki (Inventor); Hibbard, Terry L. (Inventor)

2001-01-01

Friction plug welding (FPW) usage is advantageous for friction stir welding (FSW) hole close-outs and weld repairs in 2195 Al--Cu--Li fusion or friction stir welds. Current fusion welding methods of Al--Cu--Li have produced welds containing varied defects. These areas are found by non-destructive examination both after welding and after proof testing. Current techniques for repairing typically small (<0.25) defects weaken the weldment, rely heavily on welders' skill, and are costly. Friction plug welding repairs increase strength, ductility and resistance to cracking over initial weld quality, without requiring much time or operator skill. Friction plug welding while pulling the plug is advantageous because all hardware for performing the weld can be placed on one side of the workpiece.

CAN UPPER EXTREMITY FUNCTIONAL TESTS PREDICT THE SOFTBALL THROW FOR DISTANCE: A PREDICTIVE VALIDITY INVESTIGATION

PubMed Central

Hanney, William J.; Kolber, Morey J.; Davies, George J.; Riemann, Bryan

2011-01-01

Introduction: Understanding the relationships between performance tests and sport activity is important to the rehabilitation specialist. The purpose of this study was two- fold: 1) To identify if relationships exist between tests of upper body strength and power (Single Arm Seated Shot Put, Timed Push-Up, Timed Modified Pull-Up, and The Davies Closed Kinetic Chain Upper Extremity Stability Test, and the softball throw for distance), 2) To determine which variable or group of variables best predicts the performance of a sport specific task (the softball throw for distance). Methods: One hundred eighty subjects (111 females and 69 males, aged 18-45 years) performed the 5 upper extremity tests. The Pearson product moment correlation and a stepwise regression were used to determine whether relationships existed between performance on the tests and which upper extremity test result best explained the performance on the softball throw for distance. Results: There were significant correlations (r=.33 to r=.70, p=0.001) between performance on all of the tests. The modified pull-up test was the best predictor of the performance on the softball throw for distance (r2= 48.7), explaining 48.7% of variation in performance. When weight, height, and age were added to the regression equation the r2 values increased to 64.5, 66.2, and 67.5 respectively. Conclusion: The results of this study indicate that several upper extremity tests demonstrate significant relationships with one another and with the softball throw for distance. The modified pull up test was the best predictor of performance on the softball throw for distance. PMID:21712942

Plastic Logic quits e-reader market

NASA Astrophysics Data System (ADS)

Perks, Simon

2012-07-01

A UK firm spun out from the University of Cambridge that sought to be a world leader in flexible organic electronic circuits and displays has pulled out of the competitive e-reader market as it struggles to find a commercial outlet for its technology. Plastic Logic announced in May that it is to close its development facility in Mountain View, California, with the loss of around 40 jobs.

Relationship between shoulder roll and hand propulsion in the front crawl stroke.

PubMed

Kudo, Shigetada; Sakurai, Yoshihisa; Miwa, Takahiro; Matsuda, Yuji

2017-05-01

This study re-evaluated the magnitude of hand propulsion (HP) in the pull and push phases of the front crawl stroke and investigated the association between the angular velocity of shoulder roll (ω SR ) and hand propulsive lift (HP L ). ω SR was computed in the plane normal to a forward direction for 16 skilled swimmers performing the front crawl stroke at a maximal sprinting pace. HP, hand propulsive drag (HP D ) and HP L were determined by a dynamic pressure approach. HP and HP D in the pull phase were greater than in the push phase (P < 0.05) while HP L in the pull phase was similar to that in the push phase. Eleven swimmers out of the 16 swimmers had a significant within-swimmers correlation between ω SR and HP L in the push phase (P < 0.05). That is, HP L increased in the push phase as the ω SR of rolling back to the neutral position became faster. A swimmer should use more drag for hand propulsion in the pull phase and propulsion from drag and lift equally in the push phase. Based on the relationship between ω SR and HP L in the push phase, a possible stroke technique to enhance HP L using ω SR is discussed.

Finding the Cell Center by a Balance of Dynein and Myosin Pulling and Microtubule Pushing: A Computational Study

PubMed Central

Zhu, Jie; Burakov, Anton; Rodionov, Vladimir

2010-01-01

The centrosome position in many types of interphase cells is actively maintained in the cell center. Our previous work indicated that the centrosome is kept at the center by pulling force generated by dynein and actin flow produced by myosin contraction and that an unidentified factor that depends on microtubule dynamics destabilizes position of the centrosome. Here, we use modeling to simulate the centrosome positioning based on the idea that the balance of three forces—dyneins pulling along microtubule length, myosin-powered centripetal drag, and microtubules pushing on organelles—is responsible for the centrosome displacement. By comparing numerical predictions with centrosome behavior in wild-type and perturbed interphase cells, we rule out several plausible hypotheses about the nature of the microtubule-based force. We conclude that strong dynein- and weaker myosin-generated forces pull the microtubules inward competing with microtubule plus-ends pushing the microtubule aster outward and that the balance of these forces positions the centrosome at the cell center. The model also predicts that kinesin action could be another outward-pushing force. Simulations demonstrate that the force-balance centering mechanism is robust yet versatile. We use the experimental observations to reverse engineer the characteristic forces and centrosome mobility. PMID:20980619

Friction Pull Plug Welding in Aluminum Alloys

NASA Technical Reports Server (NTRS)

Brooke, Shane A.; Bradford, Vann; Burkholder, Jonathon

2011-01-01

NASA fs Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for External Tank. FPPW was easily selected as the primary process used to close out the termination hole on the Constellation Program fs ARES I Upper Stage circumferential Self ] Reacting Friction Stir Welds (SR ]FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR ]FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process fs limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

Friction Pull Plug Welding in Aluminum Alloys

NASA Technical Reports Server (NTRS)

Brooke, Shane A.; Bradford, Vann

2012-01-01

NASA's Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for the Space Shuttle fs External Tank. FPPW was easily selected as the primary weld process used to close out the termination hole on the Constellation Program's ARES I Upper Stage circumferential Self-Reacting Friction Stir Welds (SR-FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR-FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process's limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

Actin cable distribution and dynamics arising from cross-linking, motor pulling, and filament turnover

PubMed Central

Tang, Haosu; Laporte, Damien; Vavylonis, Dimitrios

2014-01-01

The growth of fission yeast relies on the polymerization of actin filaments nucleated by formin For3p, which localizes at tip cortical sites. These actin filaments bundle to form actin cables that span the cell and guide the movement of vesicles toward the cell tips. A big challenge is to develop a quantitative understanding of these cellular actin structures. We used computer simulations to study the spatial and dynamical properties of actin cables. We simulated individual actin filaments as semiflexible polymers in three dimensions composed of beads connected with springs. Polymerization out of For3p cortical sites, bundling by cross-linkers, pulling by type V myosin, and severing by cofilin are simulated as growth, cross-linking, pulling, and turnover of the semiflexible polymers. With the foregoing mechanisms, the model generates actin cable structures and dynamics similar to those observed in live-cell experiments. Our simulations reproduce the particular actin cable structures in myoVΔ cells and predict the effect of increased myosin V pulling. Increasing cross-linking parameters generates thicker actin cables. It also leads to antiparallel and parallel phases with straight or curved cables, consistent with observations of cells overexpressing α-actinin. Finally, the model predicts that clustering of formins at cell tips promotes actin cable formation. PMID:25103242

Finding the cell center by a balance of dynein and myosin pulling and microtubule pushing: a computational study.

PubMed

Zhu, Jie; Burakov, Anton; Rodionov, Vladimir; Mogilner, Alex

2010-12-01

The centrosome position in many types of interphase cells is actively maintained in the cell center. Our previous work indicated that the centrosome is kept at the center by pulling force generated by dynein and actin flow produced by myosin contraction and that an unidentified factor that depends on microtubule dynamics destabilizes position of the centrosome. Here, we use modeling to simulate the centrosome positioning based on the idea that the balance of three forces-dyneins pulling along microtubule length, myosin-powered centripetal drag, and microtubules pushing on organelles-is responsible for the centrosome displacement. By comparing numerical predictions with centrosome behavior in wild-type and perturbed interphase cells, we rule out several plausible hypotheses about the nature of the microtubule-based force. We conclude that strong dynein- and weaker myosin-generated forces pull the microtubules inward competing with microtubule plus-ends pushing the microtubule aster outward and that the balance of these forces positions the centrosome at the cell center. The model also predicts that kinesin action could be another outward-pushing force. Simulations demonstrate that the force-balance centering mechanism is robust yet versatile. We use the experimental observations to reverse engineer the characteristic forces and centrosome mobility.

Test and analysis results for composite transport fuselage and wing structures

NASA Technical Reports Server (NTRS)

Deaton, Jerry W.; Kullerd, Susan M.; Madan, Ram C.; Chen, Victor L.

1992-01-01

Automated tow placement (ATP) and stitching of dry textile composite preforms followed by resin transfer molding (RTM) are being investigated by researchers at NASA LaRC and Douglas Aircraft Company as cost-effective manufacturing processes for obtaining damage tolerant fuselage and wing structures for transport aircraft. The Douglas work is being performed under a NASA contract entitled 'Innovative Composites Aircraft Primary Structures (ICAPS)'. Data are presented in this paper to assess the damage tolerance of ATP and RTM fuselage elements with stitched-on stiffeners from compression tests of impacted three-J-stiffened panels and from stiffener pull-off tests. Data are also presented to assess the damage tolerance of RTM wing elements which had stitched skin and stiffeners from impacted single stiffener and three blade-stiffened compression tests and stiffener pull-off tests.

Striatal abnormalities in trichotillomania: a multi-site MRI analysis.

PubMed

Isobe, Masanori; Redden, Sarah A; Keuthen, Nancy J; Stein, Dan J; Lochner, Christine; Grant, Jon E; Chamberlain, Samuel R

2018-01-01

Trichotillomania (hair-pulling disorder) is characterized by the repetitive pulling out of one's own hair, and is classified as an Obsessive-Compulsive Related Disorder. Abnormalities of the ventral and dorsal striatum have been implicated in disease models of trichotillomania, based on translational research, but direct evidence is lacking. The aim of this study was to elucidate subcortical morphometric abnormalities, including localized curvature changes, in trichotillomania. De-identified MRI scans were pooled by contacting authors of previous peer-reviewed studies that examined brain structure in adult patients with trichotillomania, following an extensive literature search. Group differences on subcortical volumes of interest were explored (t-tests) and localized differences in subcortical structure morphology were quantified using permutation testing. The pooled sample comprised N=68 individuals with trichotillomania and N=41 healthy controls. Groups were well-matched in terms of age, gender, and educational levels. Significant volumetric reductions were found in trichotillomania patients versus controls in right amygdala and left putamen. Localized shape deformities were found in bilateral nucleus accumbens, bilateral amygdala, right caudate and right putamen. Structural abnormalities of subcortical regions involved in affect regulation, inhibitory control, and habit generation, play a key role in the pathophysiology of trichotillomania. Trichotillomania may constitute a useful model through which to better understand other compulsive symptoms. These findings may account for why certain medications appear effective for trichotillomania, namely those modulating subcortical dopamine and glutamatergic function. Future work should study the state versus trait nature of these changes, and the impact of treatment.

Biomechanical and histological evaluation of an expandable pedicle screw in osteoporotic spine in sheep

PubMed Central

Wan, Shiyong; Wu, Zixiang; Liu, Da; Gao, Mingxuan; Fu, Suochao

2010-01-01

Transpedicular fixation can be challenging in the osteoporotic spine as reduced bone mineral density compromises the mechanical stability of the pedicle screw. Here, we sought to investigate the biomechanical and histological properties of stabilization of expandable pedicle screw (EPS) in the osteoporotic spine in sheep. EPSs and standard pedicle screws, SINO screws, were inserted on the vertebral bodies in four female ovariectomized sheep. Pull-out and cyclic bending resistance test were performed to compare the holding strength of these pedicle screws. High-resolution micro-computed tomography (CT) was performed for three-dimensional image reconstruction. We found that the EPSs provided a 59.6% increase in the pull-out strength over the SINO screws. Moreover, the EPSs withstood a greater number of cycles or load with less displacement before loosening. Micro-CT image reconstruction showed that the tissue mineral density, bone volume fraction, bone surface/bone volume ratio, trabecular thickness, and trabecular separation were significantly better in the expandable portion of the EPSs than those in the anterior portion of the SINO screws (P < 0.05). Furthermore, the trabecular architecture in the screw–bone interface was denser in the expandable portion of the EPS than that in the anterior portion of the SINO screw. Histologically, newly formed bone tissues grew into the center of EPS and were in close contact with the EPS. Our results show that the EPS demonstrates improved biomechanical and histological properties over the standard screw in the osteoporotic spine. The EPS may be of value in treating patients with osteoporosis and warrants further clinical studies. PMID:20577766

Press-fit acetabular cup fixation: principles and testing.

PubMed

Macdonald, W; Carlsson, L V; Charnley, G J; Jacobsson, C M

1999-01-01

Pre-clinical testing of the fixation of press-fit acetabular components of total hip prostheses relies on cadaver or synthetic bone, but the properties and geometry of bone models differ from those of physiological bone. Cup designs use varied mechanisms for initial stability in bone; therefore, using different analogues and tests is appropriate. Press-fit cup stability was tested in the following: firstly, polyurethane (PU) foam modelling cancellous support; secondly, glass-fibre reinforced epoxide (GFRE) tubes modelling acetabular cortical support; thirdly, cadaveric acetabula. Three commercial cups [Harris-Galante II (H-G-II), Zimmer; Optifix, Smith & Nephew, Richards; porous coated anatomic (PCA), Howmedica] and an experimental cup with enhanced rim fixation were tested in three modes: direct pull-out, lever-out and axial torque. The fixation stabilities measured in the PU and the GFRE models showed trends consistent with those in cadaver bone, differing in the oversizing and cup geometry. The experimental cup was significantly more secure in most modes than other cups; the H-G II and Optifix cups showed similar stabilities, lower than that of the experimental cup but greater than that of the PCA cup (analysis of variance and Tukey's highly significant test; p < 0.001). The stabilities measured in cadaver bone more closely approximated those in GFRE. The use of several bone analogues enables separation of fixation mechanisms, allowing more accurate prediction of in vivo performance.

Middle Level Learning.

ERIC Educational Resources Information Center

Rothwell, Jennifer; Levy, Tedd; Manaster, Jane; Bernson, Mary Hammond

1998-01-01

Presents a pull-out section that includes four brief articles and accompanying learning activities. The articles include an architectural examination of the move from medieval fort to Renaissance palace, interdisciplinary biographical writing assignments, a look at the portrayal of people with disabilities in juvenile literature, and material on…

Tool Removes Coil-Spring Thread Inserts

NASA Technical Reports Server (NTRS)

Collins, Gerald J., Jr.; Swenson, Gary J.; Mcclellan, J. Scott

1991-01-01

Tool removes coil-spring thread inserts from threaded holes. Threads into hole, pries insert loose, grips insert, then pulls insert to thread it out of hole. Effects essentially reverse of insertion process to ease removal and avoid further damage to threaded inner surface of hole.

Performance of strip seals in Iowa bridges, pilot study.

DOT National Transportation Integrated Search

2001-01-01

A pilot study was conducted on the premature failures of neoprene strip seals in : expansion joints in Iowa bridges. In a relatively large number of bridges, strip seals have : pulled out of the steel extrusions or otherwise failed well before the ex...

Apparatus for tensile testing plate-type ceramic specimens

DOEpatents

Liu, Kenneth C.

1993-01-01

Apparatus for tensile testing plate-type ceramic specimens having dogbone- or T-shaped end sections without introducing bending stresses in the specimens during the application of a dynamic tensile loading on the specimens is described. A pair of elongated pull rods disposed in a side-by-side relationship are used to grip the shoulders on each T-shaped end section. The pull rods are pivotally attached to a piston-displaceable, disk-shaped member so as to be longitudinally movable with respect to one another effecting the self-alignment thereof with the shoulders on the T-shaped end sections of the specimen to compensate for shoulders being located in different longitudinal positions.

Apatite Formation and Biocompatibility of a Low Young’s Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water

PubMed Central

Tanaka, Hidetatsu; Mori, Yu; Noro, Atsushi; Kogure, Atsushi; Kamimura, Masayuki; Yamada, Norikazu; Hanada, Shuji; Masahashi, Naoya; Itoi, Eiji

2016-01-01

Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young’s modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young’s modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank’s solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion. PMID:26914329

Biomechanical comparison between suture anchor and transtibial pull-out repair for posterior medial meniscus root tears.

PubMed

Feucht, Matthias J; Grande, Eduardo; Brunhuber, Johannes; Rosenstiel, Nikolaus; Burgkart, Rainer; Imhoff, Andreas B; Braun, Sepp

2014-01-01

Posterior medial meniscus root (PMMR) tears have a serious effect on knee joint biomechanics. Currently used techniques for refixation of the PMMR include the transtibial pull-out repair (TP) and suture anchor repair (SA). These techniques have not been compared biomechanically. The SA technique provides superior biomechanical properties compared with the TP technique. Controlled laboratory study. A total of 24 fresh-frozen porcine tibiae with attached intact medial menisci were used. The specimens were randomly assigned to 3 groups (8 specimens each). A standardized PMMR tear was created in 16 specimens. Refixation of the PMMR was performed by either the TP or SA technique. The native PMMR was left intact in 8 specimens. All specimens were subjected to cyclic loading followed by load-to-failure testing. Displacement after 100, 500, and 1000 cycles; maximum load to failure; stiffness; and displacement at failure were recorded. Both repair techniques showed a significantly higher displacement during cyclic loading and a significantly lower maximum load and stiffness during load-to-failure testing compared with the native PMMR (P < .05). The SA technique showed a significantly lower displacement after 100, 500, and 1000 cycles (P < .001) and a significantly higher stiffness (P = .016) compared with the TP technique. Maximum load did not differ significantly between the SA and TP techniques (P = .027, Bonferroni adjustment). No significant difference between the 3 groups was observed for displacement at failure (P > .05). The SA technique provided superior biomechanical properties compared with the TP technique. Both repair techniques did not reach the strength of the native PMMR. The favorable biomechanical properties of the SA technique might be beneficial for healing of the repaired PMMR and restoration of meniscus function. Because of inferior time zero stability compared with the native PMMR, slow rehabilitation is recommended after meniscus root repair.

Density functional theory simulation of titanium migration and reaction with oxygen in the early stages of oxidation of equiatomic NiTi alloy.

PubMed

Nolan, Michael; Tofail, Syed A M

2010-05-01

The biocompatibility of NiTi shape memory alloys (SMA) has made possible applications in self-expandable cardio-vascular stents, stone extraction baskets, catheter guide wires and other invasive and minimally invasive biomedical devices. The NiTi intermetallic alloy spontaneously forms a thin passive layer of TiO(2), which provides its biocompatibility. The oxide layer is thought to form as the Ti in the alloy surface reacts with oxygen, resulting in a depletion of Ti in the subsurface region - experimental evidence indicates formation of a Ni-rich layer below the oxide film. In this paper, we study the initial stages of oxide growth on the (110) surface of the NiTi alloy to understand the formation of alloy/oxide interface. We initially adsorb atomic and molecular oxygen on the (110) surface and then successively add O(2) molecules, up to 2 monolayer of O(2). Oxygen adsorption always results in a large energy gain. With atomic oxygen, Ti is pulled out of the surface layer leaving behind a Ni-rich subsurface region. Molecular O(2), on the other hand adsorbs dissociatively and pulls a Ti atom farther out of the surface layer. The addition of further O(2) up to 1 monolayer is also dissociative and results in complete removal of Ti from the initial surface layer. When further O(2) is added up to 2 monolayer, Ti is pulled even further out of the surface and a single thin layer of composition O-Ti-O is formed. The electronic structure shows that the metallic character of the alloy is unaffected by interaction with oxygen and formation of the oxide layer, consistent with the oxide layer being a passivant. Copyright 2010 Elsevier Ltd. All rights reserved.

Advantages of Direct Insertion of a Straight Probe Without a Guide Tube During Anterior Odontoid Screw Fixation of Odontoid Fractures.

PubMed

Park, Jin Hoon; Kang, Dong-Ho; Lee, Moon Kyu; Yoo, Byoungwoo; Jung, Sang Ku; Hwang, Soo-Hyun; Kim, Jeoung Hee; Oh, Sunkyu; Lee, Eun Jung; Jeon, Sang Ryong; Roh, Sung Woo; Rhim, Seung Chul

2016-05-01

A retrospective cohort study. The aim of this study was to compare the anterior odontoid screw fixation (AOSF) with a guide tube or with a straight probe. AOSF associates with several complications, including malpositioning, fixation loss, and screw breakage. Screw pull-out from the C2 body is the most common complication. All consecutive patients with type II or rostral shallow type III odontoid fractures who underwent AOSFs during the study period were enrolled retrospectively. The guide-tube AOSF method followed the standard published method except C3 body and C2-3 disc annulus rimming was omitted to prevent disc injury; instead, the guide tube was anchored at the anterior inferior C2 vertebra corner. After 2 screw pull-outs, the guide-tube cohort was analyzed to identify the cause of instrument failure. Thereafter, the straight-probe method was developed. A guide tube was not used. A small pilot hole was made on the most anterior side of the inferior endplate, followed by insertion of a 2.5 mm straight probe through the C2 body. Non-union and instrument failure rates and screw-direction angles of the guide-tube and straight-probe groups were recorded. The guide-tube group (n = 13) had 2 screw pull-outs and 1 non-union. The straight-probe group (n = 8) had no complications and significantly larger screw-direction angles than the guide-tube group (60.5 ± 4.63 vs. 54.8 ± 3.82 degrees; P = 0.047). Straight-probe AOSF yielded larger direction angles without injuring bone and disc. Complications were absent. The procedure was easier than guide-tube AOSF and assured sufficient engagement, even in horizontal fracture orientation cases. 3.

The Influence of Cement Morphology Parameters on the Strength of the Cement-Bone Interface in Tibial Tray Fixation.

PubMed

Nagel, Katrin; Bishop, Nicholas E; Schlegel, Ulf J; Püschel, Klaus; Morlock, Michael M

2017-02-01

The strength of the cement-bone interface in tibial component fixation depends on the morphology of the cement mantle. The purpose of this study was to identify thresholds of cement morphology parameters to maximize fixation strength using a minimum amount of cement. Twenty-three cadaveric tibiae were analyzed that had been implanted with tibial trays in previous studies and for which the pull-out strength of the tray had been measured. Specimens were separated into a group failing at the cement-bone interface (INTERFACE) and one failing in the bulk bone (BULK). Maximum pull-out strength corresponds to the ultimate strength of the bulk bone if the cement-bone interface is sufficiently strong. 3D models of the cement mantle in situ were reconstructed from computed tomography scans. The influences of bone mineral density and 6 cement morphology parameters (reflecting cement penetration, bone-cement interface, cement volume) on pull-out strength of the BULK group were determined using multiple regression analysis. The threshold of each parameter for classification of the specimens into either group was determined using receiver operating characteristic analysis. Cement penetration exceeding a mean of 1.1 mm or with a maximum of 5.6 mm exclusively categorized all BULK bone failure specimens. Failure strength of BULK failure specimens increased with bone mineral density (R 2  = 0.67, P < .001) but was independent of the cement morphology parameters. To maximize fixation strength, a mean cement penetration depth of at least 1.1 mm should be achieved during tibial tray cementing. Copyright © 2016 Elsevier Inc. All rights reserved.

Efficiency considerations for the purely tapered interference fit (TIF) abutments used in dental implants.

PubMed

Bozkaya, Dinçer; Müftü, Sinan

2004-08-01

A tapered interference fit provides a mechanically reliable retention mechanism for the implant-abutment interface in a dental implant. Understanding the mechanical properties of the tapered interface with or without a screw at the bottom has been the subject of a considerable amount of studies involving experiments and finite element (FE) analysis. In this paper, approximate closed-form formulas are developed to analyze the mechanics of a tapered interference fit. In particular, the insertion force, the efficiency, defined as the ratio of the pull-out force to insertion force, and the critical insertion depth, which causes the onset of plastic deformation, are analyzed. It is shown that the insertion force is a function of the taper angle, the contact length, the inner and outer radii of the implant, the static and the kinetic coefficients of friction, and the elastic modulii of the implant/abutment materials. The efficiency of the tapered interference fit, which is defined as the ratio of the pull-out force to insertion force, is found to be greater than one, for taper angles that are less than 6 deg when the friction coefficient is 0.3. A safe range of insertion forces has been shown to exist. The lower end of this range depends on the maximum pull-out force that may occur due to occlusion in the multiple tooth restorations and the efficiency of the system; and the upper end of this range depends on the plastic deformation of the abutment and the implant due to interference fit. It has been shown that using a small taper angle and a long contact length widens the safe range of insertion forces.

Spark plasma sintering of silicon carbide, multi-walled carbon nanotube and graphene reinforced zirconium diboride ceramic composite

NASA Astrophysics Data System (ADS)

Balaraman Yadhukulakrishnan, Govindaraajan

Scope and Method of Study: Space vehicles re-entering the earth's atmosphere experience very high temperatures due to aerodynamic heating. Ultra-high temperature ceramics (UHTC) with melting point higher than 3200°C are promising materials for thermal protection systems of such space vehicles re-entering the earth's atmosphere. Among several UHTC systems ZrB2 based ceramic composites are particularly important for thermal protection systems due to their better mechanical and thermoelectric properties and high oxidation resistance. In this study spark plasma sintering of SiC, carbon nanotubes (CNT) and graphene nano platelets (GNP) reinforced ZrB2 ultra-high temperature ceramic matrix composites is reported. Findings and Conclusions: Systematic investigations on the effect of reinforcement type (SiC, CNTs and GNP) and content (10-40 vol.% SiC, 2-6 vol.% CNTs and 2-6 vol.% GNP) on densification behavior, microstructure development, and mechanical properties (microhardness, bi-axial flexural strength, and indentation fracture toughness) are reported. With the similar SPS parameters near-full densification (>99% relative density) was achieved with 10-40 vol.% SiC, 4-6 vol.% CNT reinforced composites. Highly dense composites were obtained in 4-6 vol.% GNP reinforced composites. The SiC, CNT and GNP reinforcement improved the indentation fracture toughness of the composites through a range of toughening mechanisms, including particle shearing, crack deflection at the particle-matrix interface, and grain pull-outs for ZrB2-SiC composites, CNT pull-outs and crack deflection in ZrB2-CNT composites and crack deflection, crack bridging and GNP sheet pull-out for ZrB2 -GNP composites.

James Webb Space Telescope (JWST) Integrated Science Instruments Module (ISIM) Electronics Compartment (IEC) Conformal Shields Composite Bond Structure Qualification Test Method

NASA Technical Reports Server (NTRS)

Yew, Calinda; Stephens, Matt

2015-01-01

The JWST IEC conformal shields are mounted onto a composite frame structure that must undergo qualification testing to satisfy mission assurance requirements. The composite frame segments are bonded together at the joints using epoxy, EA 9394. The development of a test method to verify the integrity of the bonded structure at its operating environment introduces challenges in terms of requirements definition and the attainment of success criteria. Even though protoflight thermal requirements were not achieved, the first attempt in exposing the structure to cryogenic operating conditions in a thermal vacuum environment resulted in approximately 1 bonded joints failure during mechanical pull tests performed at 1.25 times the flight loads. Failure analysis concluded that the failure mode was due to adhesive cracks that formed and propagated along stress concentrated fillets as a result of poor bond squeeze-out control during fabrication. Bond repairs were made and the structures successfully re-tested with an improved LN2 immersion test method to achieve protoflight thermal requirements.

A brief description of the biomechanics and physiology of a strongman event: the tire flip.

PubMed

Keogh, Justin W L; Payne, Amenda L; Anderson, Brad B; Atkins, Paul J

2010-05-01

The purpose of this study was to (a) characterize the temporal aspects of a popular strongman event, the tire flip; (b) gain some insight into the temporal factors that could distinguish the slowest and fastest flips; and (c) obtain preliminary data on the physiological stress of this exercise. Five resistance-trained subjects with experience in performing the tire flip gave informed consent to participate in this study. Each subject performed 2 sets of 6 tire flips with a 232-kg tire with 3 minutes of rest between sets. Temporal variables were obtained from video cameras positioned 10 m from the tire, perpendicular to the intended direction of the tire flip. Using the "stopwatch" function in Silicon Coach, the duration of each tire flip and that of the first pull, second pull, transition, and push phases were recorded. Physiological stress was estimated via heart rate and finger-prick blood lactate response. Independent T-tests revealed that the 2 faster subjects (0.38 +/- 0.17 s) had significantly (p < 0.001) shorter second pull durations than the 3 slower subjects (1.49 +/- 0.92 s). Paired T-tests revealed that the duration of the second pull for each subject's fastest 3 trials (0.55 +/- 0.35 s) were significantly (p = 0.007) less than their 3 slowest trials (1.69 +/- 1.35 s). Relatively high heart rate (179 +/- 8 bpm) and blood lactate (10.4 +/- 1.3 mmol/L(-1)) values were found at the conclusion of the second set. Overall, the results of this study suggest that the duration of the second pull is a key determinant of tire flip performance and that this exercise provides relatively high degrees of physiological stress.

Routes and Reasons Out, Paths Back: The Influence of Push and Pull Reasons for Leaving School on Students' School Reengagement

ERIC Educational Resources Information Center

Boylan, Rebecca L.; Renzulli, Linda

2017-01-01

Dropout is a major issue facing our country's schools; however, many students who drop out of school later go on to finish their degree either by returning to high school or by earning a General Education Development (GED) credential. Despite this, there has been relatively little research on these students who "stopout" of high school.…

Directional preference in dogs: Laterality and "pull of the north"

PubMed Central

Adámková, Jana; Svoboda, Jan; Benediktová, Kateřina; Martini, Sabine; Nováková, Petra; Tůma, David; Kučerová, Michaela; Divišová, Michaela; Begall, Sabine; Hart, Vlastimil

2017-01-01

Laterality is a well described phenomenon in domestic dogs. It was shown that dogs, under calm Earth's magnetic field conditions, when marking their home ranges, tend to head about north- or southwards and display thus magnetic alignment. The question arises whether magnetic alignment might be affected or even compromised by laterality and vice versa. We tested the preference of dogs to choose between two dishes with snacks that were placed left and right, in different compass directions (north and east, east and south, south and west or west and north) in front of them. Some dogs were right-lateral, some left-lateral but most of them were ambilateral. There was a preference for the dish placed north compared to the one placed east of the dog ("pull of the north"). This effect was highly significant in small and medium-sized breeds but not in larger breeds, highly significant in females, in older dogs, in lateralized dogs but less significant or not significant in males, younger dogs, or ambilateral dogs. Laterality and “pull of the north” are phenomena which should be considered in diverse tasks and behavioral tests with which dogs or other animals might be confronted. The interaction and possible conflict between lateralization and "pull of the north" might be also considered as a reason for shifted magnetic alignment observed in different animal species in different contexts. PMID:28945773

Directional preference in dogs: Laterality and "pull of the north".

PubMed

Adámková, Jana; Svoboda, Jan; Benediktová, Kateřina; Martini, Sabine; Nováková, Petra; Tůma, David; Kučerová, Michaela; Divišová, Michaela; Begall, Sabine; Hart, Vlastimil; Burda, Hynek

2017-01-01

Laterality is a well described phenomenon in domestic dogs. It was shown that dogs, under calm Earth's magnetic field conditions, when marking their home ranges, tend to head about north- or southwards and display thus magnetic alignment. The question arises whether magnetic alignment might be affected or even compromised by laterality and vice versa. We tested the preference of dogs to choose between two dishes with snacks that were placed left and right, in different compass directions (north and east, east and south, south and west or west and north) in front of them. Some dogs were right-lateral, some left-lateral but most of them were ambilateral. There was a preference for the dish placed north compared to the one placed east of the dog ("pull of the north"). This effect was highly significant in small and medium-sized breeds but not in larger breeds, highly significant in females, in older dogs, in lateralized dogs but less significant or not significant in males, younger dogs, or ambilateral dogs. Laterality and "pull of the north" are phenomena which should be considered in diverse tasks and behavioral tests with which dogs or other animals might be confronted. The interaction and possible conflict between lateralization and "pull of the north" might be also considered as a reason for shifted magnetic alignment observed in different animal species in different contexts.

Bone anchors or interference screws? A biomechanical evaluation for autograft ankle stabilization.

PubMed

Jeys, Lee; Korrosis, Sotiris; Stewart, Todd; Harris, Nicholas J

2004-01-01

Autograft stabilization uses free semitendinosus tendon grafts to anatomically reconstruct the anterior talofibular ligament. Study aims were to evaluate the biomechanical properties of Mitek GII anchors compared with the Arthrex Bio-Tenodesis Screw for free tendon reconstruction of the anterior talofibular ligament. There are no differences in load to failure and percentage specimen elongation at failure between the 2 methods. Controlled laboratory study using porcine models. Sixty porcine tendon constructs were failure tested. Re-creating the pull of the anterior talofibular ligament, loads were applied at 70 degrees to the bones. Thirty-six tendons were fixed to porcine tali and tested using a single pull to failure; 10 were secured with anchors and No. 2 Ethibond, 10 with anchors and FiberWire, 10 with screws and Fiberwire, and 6 with partially gripped screws. Cyclic preloading was conducted on 6 tendons fixed by anchors and on 6 tendons fixed by screws before failure testing. Two groups of 6 components fixed to the fibula were also tested. The talus single-pull anchor group produced a mean load of 114 N and elongation of 37% at failure. The talus single-pull screw group produced a mean load of 227 N and elongation of 22% at failure (P <.05). Cyclic preloading at 65% failure load before failure testing produced increases in load and decreases in elongation at failure. Partially gripped screws produced a load of 133 N and elongation of 30% at failure. The fibula model produced significant increases in load to failure for both. The human anterior talofibular ligament has loads of 139 N at failure with instability occurring at 20% elongation. Interference screw fixation produced significantly greater failure strength and less elongation at failure than bone anchors. The improved biomechanics of interference screws suggests that these may be more suited to in vivo reconstruction of the anterior talofibular ligament than are bone anchors.

Development of Mackintosh Probe Extractor

NASA Astrophysics Data System (ADS)

Rahman, Noor Khazanah A.; Kaamin, Masiri; Suwandi, Amir Khan; Sahat, Suhaila; Jahaya Kesot, Mohd

2016-11-01

Dynamic probing is a continuous soil investigation technique, which is one of the simplest soil penetration test. It basically consist of repeatedly driving a metal tipped probe into the ground using a drop weight of fixed mass and travel. Testing was carried out continuously from ground level to the final penetration depth. Once the soil investigation work done, it is difficult to pull out the probe rod from the ground, due to strong soil structure grip against probe cone and prevent the probe rod out from the ground. Thus, in this case, a tool named Extracting Probe was created to assist in the process of retracting the probe rod from the ground. In addition, Extracting Probe also can reduce the time to extract the probe rod from the ground compare with the conventional method. At the same time, it also can reduce manpower cost because only one worker involve to handle this tool compare with conventional method used two or more workers. From experiment that have been done we found that the time difference between conventional tools and extracting probe is significant, average time difference is 155 minutes. In addition the extracting probe can reduce manpower usage, and also labour cost for operating the tool. With all these advantages makes this tool has the potential to be marketed.

49 CFR 393.76 - Sleeper berths.

Code of Federal Regulations, 2010 CFR

2010-10-01

... case of a sleeper berth which utilizes an adjustable mechanical suspension system, the required... communication may consist of a telephone, speaker tube, buzzer, pull cord, or other mechanical or electrical...) A mattress filled with a fluid and of sufficient thickness when filled to prevent “bottoming-out...

Local Hero.

ERIC Educational Resources Information Center

Rist, Marilee C.

1992-01-01

Shows how a former high school principal (with no doctorate, central office experience, or big-city political savvy) pulled the Cincinnati (Ohio) schools out of a $76 million debt and implemented reforms recommended by the Buenger Commission. The new superintendent slashed central office positions, reorganized 86 schools into 9 minidistricts, and…

Williams watches plastic bags float in the U.S. Laboratory during Expedition 13

NASA Image and Video Library

2006-04-26

ISS013-E-13224 --- Inside the U.S. laboratory, astronaut Jeffrey N. Williams, Expedition 13 flight engineer and NASA science officer, pulls out some food items from among personal supplies for the current inhabitants of the International Space Station.

Study on bond behaviour exposed to fire using beam specimen

NASA Astrophysics Data System (ADS)

Suhaib Ahmad, Mohammad; Bhargava, Pradeep; Sharma, Umesh Kumar

2018-04-01

The composite action of concrete and steel in a reinforced concrete structure depends upon the bond between them. Bond behaviour is studied in terms of bond-slip relationship. The bond between them depends upon mechanical properties of concrete and steel. In an event of fire these mechanical properties degrades and hence the bond behaviour changes. Some researches were performed to study the effect of temperature on the bond-slip relationship which are based on pull out specimens. Generally these relationships are obtained using pull out specimen which over estimates the bond properties. In this study beam specimens were used which is recommended by Rilem. These specimens were exposed to elevated temperatures up to 650 °C and there bond-slip behaviour were studied. The study shows that bond strength decreases while peak slip increases with increases in temperature. Also an equation proposed was proposed which can predict the bond strength between concrete and steel exposed up to the temperature of 650 °C.

Multiple switch actuator

DOEpatents

Beyer, Edward T.

1976-01-06

The present invention relates to switches and switch actuating devices to be operated for purposes of arming a bomb or other missile as it is dropped or released from an aircraft. The particular bomb or missile in which this invention is applied is one in which there is a plurality of circuits which are to be armed by the closing of switches upon dropping or releasing of the bomb. The operation of the switches to closed position is normally accomplished by means of a pull-out wire; that is, a wire which is withdrawn from the bomb or missile at the time of release of the bomb, one end of the wire being attached to the aircraft. The conditions to be met are that the arming switches must be positively and surely maintained in open position until the bomb is released and the arming action is effected. The action of the pull-out wire in achieving the arming action must be sure and positive with minimum danger of malfunctioning, jamming or binding.

Assessment of Anaerobic Metabolic Activity and Microbial Diversity in a Petroleum-Contaminated Aquifer Using Push-Pull Tests in Combination With Molecular Tools and Stable Isotopes

NASA Astrophysics Data System (ADS)

Schroth, M. H.; Kleikemper, J.; Pombo, S. A.; Zeyer, J.

2002-12-01

In the past, studies on microbial communities in natural environments have typically focused on either their structure or on their metabolic function. However, linking structure and function is important for understanding microbial community dynamics, in particular in contaminated environments. We will present results of a novel combination of a hydrogeological field method (push-pull tests) with molecular tools and stable isotope analysis, which was employed to quantify anaerobic activities and associated microbial diversity in a petroleum-contaminated aquifer in Studen, Switzerland. Push-pull tests consisted of the injection of test solution containing a conservative tracer and reactants (electron acceptors, 13C-labeled carbon sources) into the aquifer anoxic zone. Following an incubation period, the test solution/groundwater mixture was extracted from the same location. Metabolic activities were computed from solute concentrations measured during extraction. Simultaneously, microbial diversity in sediment and groundwater was characterized by using fluorescence in situ hybridization (FISH), denaturing gradient gel electrophoresis (DGGE), as well as phospholipids fatty acid (PLFA) analysis in combination with 13C isotopic measurements. Results from DGGE analyses provided information on the general community structure before, during and after the tests, while FISH yielded information on active populations. Moreover, using 13C-labeling of microbial PLFA we were able to directly link carbon source assimilation in an aquifer to indigenous microorganisms while providing quantitative information on respective carbon source consumption.

Association between anthropometry and upper-body strength qualities with sprint paddling performance in competitive wave surfers.

PubMed

Sheppard, Jeremy M; McNamara, Phil; Osborne, Mark; Andrews, Mark; Oliveira Borges, Thiago; Walshe, Phil; Chapman, Dale W

2012-12-01

This study aimed to evaluate the potential association with anthropometry and upper-body pulling strength with sprint kinematics of competitive surfers. Ten competitive male surfers (23.9 ± 6.8 years, 177.0 ± 6.5 cm, 72.2 ± 2.4 kg) were assessed for stature, mass, arm span, ∑ 7 site skinfold thickness, pronated pull-up strength, and sprint paddling performance from a stationary start to 15 m. Pearson correlation analysis, and independent t-tests were used to compare potential differences between the slower and faster group of sprint paddlers. Strong associations were found between relative (total kilograms lifted per athlete mass) upper-body pulling strength and sprint paddling time to 5, 10, and 15 m, and peak sprint paddling velocity (r = 0.94, 0.93, 0.88, 0.66, respectively, p < 0.05) and relative upper-body pulling strength was found to be superior (p < 0.05) in the faster group, with large effect (d = 1.88). The results of this study demonstrate a strong association between relative upper-body pulling strength and sprint paddling ability in surfers. Strength and conditioning coaches working with competitive surfers should implement strength training with surfers, including an emphasis on developing relative strength, because this may have a strong influence on sprint paddling performance.

Competitive control of cognition in rhesus monkeys.

PubMed

Kowaguchi, Mayuka; Patel, Nirali P; Bunnell, Megan E; Kralik, Jerald D

2016-12-01

The brain has evolved different approaches to solve problems, but the mechanisms that determine which approach to take remain unclear. One possibility is that control progresses from simpler processes, such as associative learning, to more complex ones, such as relational reasoning, when the simpler ones prove inadequate. Alternatively, control could be based on competition between the processes. To test between these possibilities, we posed the support problem to rhesus monkeys using a tool-use paradigm, in which subjects could pull an object (the tool) toward themselves to obtain an otherwise out-of-reach goal item. We initially provided one problem exemplar as a choice: for the correct option, a food item placed on the support tool; for the incorrect option, the food item placed off the tool. Perceptual cues were also correlated with outcome: e.g., red, triangular tool correct, blue, rectangular tool incorrect. Although the monkeys simply needed to touch the tool to register a response, they immediately pulled it, reflecting a relational reasoning process between themselves and another object (R self-other ), rather than an associative one between the arbitrary touch response and reward (A resp-reward ). Probe testing then showed that all four monkeys used a conjunction of perceptual features to select the correct option, reflecting an associative process between stimuli and reward (A stim-reward ). We then added a second problem exemplar and subsequent testing revealed that the monkeys switched to using the on/off relationship, reflecting a relational reasoning process between two objects (R other-other ). Because behavior appeared to reflect R self-other rather than A resp-reward , and A stim-reward prior to R other-other , our results suggest that cognitive processes are selected via competitive control dynamics. Copyright © 2016 Elsevier B.V. All rights reserved.

Future Food Production System Development Pulling From Space Biology Crop Growth Testing in Veggie

NASA Technical Reports Server (NTRS)

Massa, Gioia; Romeyn, Matt; Fritsche, Ralph

2017-01-01

Preliminary crop testing using Veggie indicates the environmental conditions provided by the ISS are generally suitable for food crop production. When plant samples were returned to Earth for analysis, their levels of nutrients were comparable to Earth-grown ground controls. Veggie-grown produce food safety microbiology analysis indicated that space-grown crops are safe to consume. Produce sanitizing wipes were used on-orbit to further reduce risk of foodborne illness. Validation growth tests indicated abiotic challenges of insufficient or excess fluid delivery, potentially reduced air flow leading to excess water, elevated CO2 leading to physiological responses, and microorganisms that became opportunistic pathogens. As NASA works to develop future space food production, several areas of research to define these systems pull from the Veggie technology validation tests. Research into effective, reusable water delivery and water recovery methods for future food production systems arises from abiotic challenges observed. Additionally, impacts of elevated CO2 and refinement of fertilizer and light recipes for crops needs to be assessed. Biotic pulls include methods or technologies to effectively sanitize produce with few consumables and low inputs; work to understand the phytomicrobiome and potentially use it to protect crops or enhance growth; selection of crops with high harvest index and desirable flavors for supplemental nutrition; crops that provide psychosocial benefits, and custom space crop development. Planning for future food production in a deep space gateway or a deep space transit vehicle requires methods of handling and storing seeds, and ensuring space seeds are free of contaminants and long-lived. Space food production systems may require mechanization and autonomous operation, with preliminary testing initiated to identify operations and capabilities that are candidates for automation. Food production design is also pulling from Veggie logistics lessons, as we learn about growing at different scales and move toward developing systems that require less launch mass. Veggie will be used as a test bed for novel food production technologies. Veggie is a relatively simple precursor food production system but the knowledge gained from space biology validation tests in Veggie will have far reaching repercussions on future exploration food production. This work is supported by NASA.

Future Food Production System Development Pulling from Space Biology Crop Growth Testing in Veggie

NASA Technical Reports Server (NTRS)

Massa, G. D.; Romeyn, M. W.; Fritsche, R. F.

2017-01-01

Preliminary crop testing using Veggie indicates the environmental conditions provided by the ISS are generally suitable for food crop production. When plant samples were returned to Earth for analysis, their levels of nutrients were comparable to Earth-grown ground controls. Veggie-grown produce food safety microbiology analysis indicated that space-grown crops are safe to consume. Produce sanitizing wipes were used on-orbit to further reduce risk of foodborne illness. Validation growth tests indicated abiotic challenges of insufficient or excess fluid delivery, potentially reduced air flow leading to excess water, elevated CO2 leading to physiological responses, and microorganisms that became opportunistic pathogens. As NASA works to develop future space food production, several areas of research to define these systems pull from the Veggie technology validation tests. Research into effective, reusable water delivery and water recovery methods for future food production systems arises from abiotic challenges observed. Additionally, impacts of elevated CO2 and refinement of fertilizer and light recipes for crops needs to be assessed. Biotic pulls include methods or technologies to effectively sanitize produce with few consumables and low inputs; work to understand the phytomicrobiome and potentially use it to protect crops or enhance growth; selection of crops with high harvest index and desirable flavors for supplemental nutrition; crops that provide psychosocial benefits, and custom space crop development. Planning for future food production in a deep space gateway or a deep space transit vehicle requires methods of handling and storing seeds, and ensuring space seeds are free of contaminants and long-lived. Space food production systems may require mechanization and autonomous operation, with preliminary testing initiated to identify operations and capabilities that are candidates for automation. Food production design is also pulling from Veggie logistics lessons, as we learn about growing at different scales and move toward developing systems that require less launch mass. Veggie will be used as a test bed for novel food production technologies. Veggie is a relatively simple precursor food production system but the knowledge gained from space biology validation tests in Veggie will have far reaching repercussions on future exploration food production.

Surface, interphase and tensile properties of unsized, sized and heat treated basalt fibres

NASA Astrophysics Data System (ADS)

Förster, T.; Sommer, G. S.; Mäder, E.; Scheffler, C.

2016-07-01

Recycling of fibre reinforced polymers is in the focus of several investigations. Chemical and thermal treatments of composites are the common ways to separate the reinforcing fibres from the polymer matrices. However, most sizings on glass and basalt fibre are not designed to resist high temperatures. Hence, a heat treatment might also lead to a sizing removal, a decrease of mechanical performance and deterioration in fibre-matrix adhesion. Different basalt fibres were investigated using surface analysis methods as well as single fibre tensile tests and single fibre pull-out tests in order to reveal the possible causes of these issues. Heat treatment in air reduced the fibre tensile strength in the same level like heat treatment in nitrogen atmosphere, but it influenced the wetting capability. Re-sizing by a coupling agent slightly increased the adhesion strength and reflected a decreased post-debonding friction.

Bond characteristics of reinforcing steel embedded in geopolymer concrete

NASA Astrophysics Data System (ADS)

Kathirvel, Parthiban; Thangavelu, Manju; Gopalan, Rashmi; Raja Mohan Kaliyaperumal, Saravana

2017-07-01

The force transferring between reinforcing steel and the surrounding concrete in reinforced concrete is influenced by several factors. Whereas, the study on bond behaviour of geopolymer concrete (GPC) is lagging. In this paper, an experimental attempt has been made to evaluate the geopolymer concrete bond with reinforcing steel of different diameter and embedded length using standard pull out test. The geopolymer concrete is made of ground granulated blast furnace slag (GGBFS) as geopolymer source material (GSM). The tests were conducted to evaluate the development of bond between steel and concrete of grade M40 and M50 with 12 and 16 mm diameter reinforcing steel for geopolymer and cement concrete mixes and to develop a relation between bond strength and compressive strength. From the experimental results, it has been observed that the bond strength of the geopolymer concrete mixes was more compared to the cement concrete mixes and increases with the reduction in the diameter of the bar.

Improved Quick-Release Pin Mechanism

NASA Technical Reports Server (NTRS)

Wright, Jay M.

2007-01-01

An improved quick-release pin mechanism supplants a prior such mechanism in which the pin bears a shear load to hold two objects together. The prior mechanism, of a ball-locking design, can fail when vibrations cause balls to fall out. The load-bearing pin is an outer tube with a handle at one end (hereafter denoted the near end). Within the outer tube is a spring-loaded inner tube that includes a handle at its near end and a pivoting tab at its far end. The pin is inserted through holes in the objects to be retained and the inner tube is pushed against an offset pivot inside the outer tube to make the tab rotate outward so that it protrudes past the outer diameter of the outer tube, and the spring load maintains this configuration so that the pin cannot be withdrawn through the holes. Pushing the handles together against the spring load moves the locking tab out far enough that the tab becomes free to rotate inward. Then releasing the inner-tube handle causes the tab to be pulled into a resting position inside the outer tube. The pin can then be pulled out through the holes.

Mechanics of the tapered interference fit in dental implants.

PubMed

Bozkaya, Dinçer; Müftü, Sinan

2003-11-01

In evaluation of the long-term success of a dental implant, the reliability and the stability of the implant-abutment interface plays a great role. Tapered interference fits provide a reliable connection method between the abutment and the implant. In this work, the mechanics of the tapered interference fits were analyzed using a closed-form formula and the finite element (FE) method. An analytical solution, which is used to predict the contact pressure in a straight interference, was modified to predict the contact pressure in the tapered implant-abutment interface. Elastic-plastic FE analysis was used to simulate the implant and abutment material behavior. The validity and the applicability of the analytical solution were investigated by comparisons with the FE model for a range of problem parameters. It was shown that the analytical solution could be used to determine the pull-out force and loosening-torque with 5-10% error. Detailed analysis of the stress distribution due to tapered interference fit, in a commercially available, abutment-implant system was carried out. This analysis shows that plastic deformation in the implant limits the increase in the pull-out force that would have been otherwise predicted by higher interference values.

Through thickness mechanical properties of chemical vapor infiltration and nano-infiltration and transient eutectic-phase processed SiC/SiC composites

DOE PAGES

Shih, Chunghao Phillip; Katoh, Yutai; Ozawa, Kazumi; ...

2014-04-08

The through thickness (interlaminar) shear strength and trans-thickness tensile strength of three different nuclear-grade SiC/SiC composites were evaluated at room temperature by the double-notched shear and diametral compression tests, respectively. With increasing densification of the interlaminar matrix region, a transition in failure locations from interlayer to intrafiber bundle was observed, along with significant increases in the value of the interlaminar shear strength. Under trans-thickness tensile loading, cracks were found to propagate easily in the unidirectional composite. Furthermore, the 2D woven composite had a higher trans-thickness tensile strength (38 MPa) because the failure mode involved debonding, fiber pull-out and fiber failure.

Through thickness mechanical properties of chemical vapor infiltration and nano-infiltration and transient eutectic-phase processed SiC/SiC composites

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

Shih, Chunghao Phillip; Katoh, Yutai; Ozawa, Kazumi

The through thickness (interlaminar) shear strength and trans-thickness tensile strength of three different nuclear-grade SiC/SiC composites were evaluated at room temperature by the double-notched shear and diametral compression tests, respectively. With increasing densification of the interlaminar matrix region, a transition in failure locations from interlayer to intrafiber bundle was observed, along with significant increases in the value of the interlaminar shear strength. Under trans-thickness tensile loading, cracks were found to propagate easily in the unidirectional composite. Furthermore, the 2D woven composite had a higher trans-thickness tensile strength (38 MPa) because the failure mode involved debonding, fiber pull-out and fiber failure.

Modeling the macrodynamics of international migration: determinants of emigration from Cyprus, 1946-85.

PubMed

Diamantides, N D; Constantinou, S T

1989-07-01

"A model is presented of international migration that is based on the concept of a pool of potential emigrants at the origin created by push-pull forces and by the establishment of information feedback between origin and destination. The forces can be economic, political, or both, and are analytically expressed by the 'mediating factor'. The model is macrodynamic in nature and provides both for the main secular component of the migratory flow and for transient components caused by extraordinary events. The model is expressed in a Bernoulli-type differential equation through which quantitative weights can be derived for each of the operating causes. Out-migration from the Republic of Cyprus is used to test the tenets of the model." excerpt

The Balanced Scorecard

ERIC Educational Resources Information Center

Kaplan, Robert S.; Miyake, Dylan N.

2010-01-01

Ten years ago, the Atlanta Public Schools had low and declining student achievement, demoralized teachers, crumbling buildings, high turnover among superintendents (average tenure of two years) and disaffected parents pulling their children out of the system. More than 60 percent of the city's high school students missed at least two weeks of…

Outdoor Education Units. Pull Out Feature.

ERIC Educational Resources Information Center

Levi, Jan

2001-01-01

Briefly presents 15 outdoor education units covering orienteering, map reading, safety, rescue, rope skills, first aid, camping, kayaking, rock and wall climbing, caving, survival skills, sailing, hiking, and outdoor equipment. Each unit has a brief description, including the knowledge and skills that students should be able to demonstrate. (TD)

Department of the Navy FY 1994 Budget Estimates. R, D, T & E Descriptive Summaries Submitted to Congress April 1993

DTIC Science & Technology

1993-04-01

8217 (0) Complete fielding of system via instatllation and testing at each site; reach Pull Operational capability. C. (U) Transition software to the...covert naval operations. The goaLis to develop technology required to of Special Warfare units. An important See-Air-Land (SEAL) mission is the pre...by the COPERNICUS concept of "user pull ". Architecture will be consistent with DOD Global Grid. This ATD complements the DARPA WJAR]EA] Initiative. b

42 CFR Appendix - Tables to Subpart H of Part 84

Code of Federal Regulations, 2012 CFR

2012-10-01

... at 9.7 km. (6 miles) per hour 1 1 1 1 1 1 1 Pulls 20 kg. (45 pound) weight to 5 feet 15 times in 1... km. (3 miles) per hour 1 1 1 2 2 2 Pulls 20 kg. (45 pound) weight to 5 feet 30 times in 2 minutes 30... Sampling and readings 2 2 2 2 Perform 1 hour test 2, 3, or 4 times respectively. Walks at 4.8 km. (3 miles...

42 CFR Appendix - Tables to Subpart H of Part 84

Code of Federal Regulations, 2014 CFR

2014-10-01

... at 9.7 km. (6 miles) per hour 1 1 1 1 1 1 1 Pulls 20 kg. (45 pound) weight to 5 feet 15 times in 1... km. (3 miles) per hour 1 1 1 2 2 2 Pulls 20 kg. (45 pound) weight to 5 feet 30 times in 2 minutes 30... Sampling and readings 2 2 2 2 Perform 1 hour test 2, 3, or 4 times respectively. Walks at 4.8 km. (3 miles...

42 CFR Appendix - Tables to Subpart H of Part 84

Code of Federal Regulations, 2013 CFR

2013-10-01

... at 9.7 km. (6 miles) per hour 1 1 1 1 1 1 1 Pulls 20 kg. (45 pound) weight to 5 feet 15 times in 1... km. (3 miles) per hour 1 1 1 2 2 2 Pulls 20 kg. (45 pound) weight to 5 feet 30 times in 2 minutes 30... Sampling and readings 2 2 2 2 Perform 1 hour test 2, 3, or 4 times respectively. Walks at 4.8 km. (3 miles...

Vacuum Head Checks Foam/Substrate Bonds

NASA Technical Reports Server (NTRS)

Lloyd, James F.

1989-01-01

Electromechanical inspection system quickly gives measurements indicating adhesion, or lack thereof, between rigid polyurethane foam and aluminum substrate. Does not damage inspected article, easy to operate, and used to perform "go/no-go" evaluations or as supplement to conventional destructive pull-plug testing. Applies vacuum to small area of foam panel and measures distance through which foam pulled into vacuum. Probe head applied to specimen and evacuated through hose to controller/monitor unit. Digital voltmeter in unit reads deflection of LVDT probe head.

Advanced Concept

NASA Image and Video Library

2003-12-01

This photo gives an overhead look at an RS-88 development rocket engine being test fired at NASA's Marshall Space Flight Center in Huntsville, Alabama, in support of the Pad Abort Demonstration (PAD) test flights for NASA's Orbital Space Plane (OSP). The tests could be instrumental in developing the first crew launch escape system in almost 30 years. Paving the way for a series of integrated PAD test flights, the engine tests support development of a system that could pull a crew safely away from danger during liftoff. A series of 16 hot fire tests of a 50,000-pound thrust RS-88 rocket engine were conducted, resulting in a total of 55 seconds of successful engine operation. The engine is being developed by the Rocketdyne Propulsion and Power unit of the Boeing Company. Integrated launch abort demonstration tests in 2005 will use four RS-88 engines to separate a test vehicle from a test platform, simulating pulling a crewed vehicle away from an aborted launch. Four 156-foot parachutes will deploy and carry the vehicle to landing. Lockheed Martin is building the vehicles for the PAD tests. Seven integrated tests are plarned for 2005 and 2006.

Advanced Concept

NASA Image and Video Library

2003-12-01

In this photo, an RS-88 development rocket engine is being test fired at NASA's Marshall Space Flight Center in Huntsville, Alabama, in support of the Pad Abort Demonstration (PAD) test flights for NASA's Orbital Space Plane (OSP). The tests could be instrumental in developing the first crew launch escape system in almost 30 years. Paving the way for a series of integrated PAD test flights, the engine tests support development of a system that could pull a crew safely away from danger during liftoff. A series of 16 hot fire tests of a 50,000-pound thrust RS-88 rocket engine were conducted, resulting in a total of 55 seconds of successful engine operation. The engine is being developed by the Rocketdyne Propulsion and Power unit of the Boeing Company. Integrated launch abort demonstration tests in 2005 will use four RS-88 engines to separate a test vehicle from a test platform, simulating pulling a crewed vehicle away from an aborted launch. Four 156-foot parachutes will deploy and carry the vehicle to landing. Lockheed Martin is building the vehicles for the PAD tests. Seven integrated tests are plarned for 2005 and 2006.

On the tree stability risk

NASA Astrophysics Data System (ADS)

Giambastiani, Yamuna; Preti, Federico; Errico, Alessandro; Penna, Daniele

2017-04-01

There is growing interest in developing models for predicting how root anchorage and tree bracing could influence tree stability. This work presents the results of different experiments aimed at evaluating the mechanical response of plate roots to pulling tests. Pulling tests have been executed with increasing soil water content and soil of different texture. Different types of tree bracing have been examined for evaluating its impact on plant stiffness. Root plate was anchored with different systems for evaluating the change in overturning resistance. The first results indicate that soil water content contributed to modify both the soil cohesion and the stabilizing forces. Wind effect, slope stability and root reinforcement could be better quantified by means of such a results.

How does a soap film burst during generation?

NASA Astrophysics Data System (ADS)

Rio, Emmanuelle; Saulnier, Laurie; Restagno, Frederic; Langevin, Dominique

2011-11-01

Foams are dispersions of bubbles in a liquid matrix in the presence of stabilizing surfactants. Even if foams are ubiquitous, the ability of a solution to create a certain foam quantity is still not fully understood. As a first step, we choose to work on a simplified system and studied the stability of a soap film during its generation. We have built an experiment, in which we determine simultaneously the velocity of a frame pulled out of a soapy solution and the entire shape of the liquid film. We found that the film is made of two parts: the bottom part is of uniform and stationary thickness, well described by the classical Frankel's law; in the top part, the film drains until a black film appears near the frame upper boundary frame, and then bursts. In this study, we characterize both part of the films and show that the Frankel law breaks down at high capillary number due to surfactants confinement. We also explain why films pulled at high velocity have a shorter lifetime than those pulled at low velocity. L. Saulnier is funded by CNES.

Characteristics and applications of high-performance fiber reinforced asphalt concrete

NASA Astrophysics Data System (ADS)

Park, Philip

Steel fiber reinforced asphalt concrete (SFRAC) is suggested in this research as a multifunctional high performance material that can potentially lead to a breakthrough in developing a sustainable transportation system. The innovative use of steel fibers in asphalt concrete is expected to improve mechanical performance and electrical conductivity of asphalt concrete that is used for paving 94% of U. S. roadways. In an effort to understand the fiber reinforcing mechanisms in SFRAC, the interaction between a single straight steel fiber and the surrounding asphalt matrix is investigated through single fiber pull-out tests and detailed numerical simulations. It is shown that pull-out failure modes can be classified into three types: matrix, interface, and mixed failure modes and that there is a critical shear stress, independent of temperature and loading rate, beyond which interfacial debonding will occur. The reinforcing effects of SFRAC with various fiber sizes and shapes are investigated through indirect tension tests at low temperature. Compared to unreinforced specimens, fiber reinforced specimens exhibit up to 62.5% increase in indirect tensile strength and 895% improvements in toughness. The documented improvements are the highest attributed to fiber reinforcement in asphalt concrete to date. The use of steel fibers and other conductive additives provides an opportunity to make asphalt pavement electrically conductive, which opens up the possibility for multifunctional applications. Various asphalt mixtures and mastics are tested and the results indicate that the electrical resistivity of asphaltic materials can be manipulated over a wide range by replacing a part of traditional fillers with a specific type of graphite powder. Another important achievement of this study is development and validation of a three dimensional nonlinear viscoelastic constitutive model that is capable of simulating both linear and nonlinear viscoelasticity of asphaltic materials. The developed model is formulated in finite strain for asphalt binder and in infinitesimal strain for asphalt concrete. Comparisons to published test data show that the model is capable of modeling behavior over a wide range of stress, temperature and strain rate conditions. The performance of asphalt plug joints (APJ) which are used as expansion joints in bridges is investigated. The study sheds light on the reasons for premature APJ failures observed in the field, based on which improved joint details are proposed.

Biomechanical characteristics of bioabsorbable magnesium-based (MgYREZr-alloy) interference screws with different threads.

PubMed

Ezechieli, Marco; Ettinger, Max; König, Carolin; Weizbauer, Andreas; Helmecke, Patrick; Schavan, Robert; Lucas, Arne; Windhagen, Henning; Becher, Christoph

2016-12-01

Degradable magnesium implants have received increasing interest in recent years. In anterior cruciate ligament reconstruction surgery, the well-known osteoconductive effects of biodegradable magnesium alloys may be useful. The aim of this study was to examine whether interference screws made of MgYREZr have comparable biomechanical properties to commonly used biodegradable screws and whether a different thread on the magnesium screw has an influence on the fixation strength. Five magnesium (MgYREZr-alloy) screws were tested per group. Three different groups with variable thread designs (Designs 1, 2, and 3) were produced and compared with the commercially available bioabsorbable Bioacryl rapid polylactic-co-glycolic acid screw Milagro ® . In vitro testing was performed in synthetic bone using artificial ligament fixed by an interference screw. The constructs were pretensioned with a constant load of 60 N for 30 s followed by 500 cycles between 60 N and 250 N at 1 Hz. Construct displacements between the 1st and 20th and the 21st and 500th cycles were recorded. After a 30 s break, a maximum load to failure test was performed at 1 mm/s measuring the maximum pull-out force. The maximum loads to failure of all three types of magnesium interference screws (Design 1: 1,092 ± 133.7 N; Design 2: 1,014 ± 103.3 N; Design 3: 1,001 ± 124 N) were significantly larger than that of the bioabsorbable Milagro ® interference screw (786.8 ± 62.5 N) (p < 0.05). However, the greatest maximum load was found with magnesium screw Design 1. Except for a significant difference between Designs 1 and 2, there were no further significant differences among the four groups in displacement after the 20th cycle. Biomechanical testing showed higher pull-out forces for magnesium compared with a commercial polymer screw. Hence, they suggest better stability and are a potential alternative. The thread geometry does not significantly influence the stability provided by the magnesium implants. This study shows the first promising results of a degradable material, which may be a clinical alternative in the future.

The Iran Sanctions Act (ISA)

DTIC Science & Technology

2009-03-09

September 1997) for Total SA of France and its partners, Gazprom of Russia and Petronas of Malaysia to develop phases 2 and 3 of the 25-phase South...announced pullouts or declined further investment. On July 12, 2008, Total and Petronas , the original South Pars investors, pulled out of a deal to

The Iran Sanctions Act (ISA)

DTIC Science & Technology

2009-02-02

billion4 contract (September 1997) for Total SA of France and its partners, Gazprom of Russia and Petronas of Malaysia to develop phases 2 and 3 of...or declined further investment. On July 12, 2008, Total and Petronas , the original South Pars investors, pulled out of a deal to develop a

The Iran Sanctions Act (ISA)

DTIC Science & Technology

2009-05-01

partners, Gazprom of Russia and Petronas of Malaysia to develop phases 2 and 3 of the 25-phase South Pars gas field. The EU pledged to increase...July 12, 2008, Total and Petronas , the original South Pars investors, pulled out of a deal to develop a liquified natural gas (LNG) export capability

The Iran Sanctions Act (ISA)

DTIC Science & Technology

2009-04-14

of Russia and Petronas of Malaysia to develop phases 2 and 3 of the 25-phase South Pars gas field. The EU pledged to increase cooperation with the...and Petronas , the original South Pars investors, pulled out of a deal to develop a liquified natural gas (LNG) export capability at Phase 11 of South

Atlanta's Own "Hall" of Famer

ERIC Educational Resources Information Center

Maxwell, Lesil A.

2008-01-01

This article features Beverly L. Hall, poised to become one of the longest-serving superintendents of the Atlanta schools. When she came to Atlanta in 1999, student achievement was sliding downward, teacher morale was dismal, and enrollment was falling as parents pulled their children out of the school system. Under the superintendent's driving…

40. Coffee bean drying trays that are stored in racks ...

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

40. Coffee bean drying trays that are stored in racks under building and pulled out to sun dry beans on terraces to the north and south of building. HAER PR, 6-MAGU, 1C-3 - Hacienda Buena Vista, PR Route 10 (Ponce to Arecibo), Magueyes, Ponce Municipio, PR

School Effects on Performance of Minority Pupils.

ERIC Educational Resources Information Center

Hofman, W. H. Adriaan

1994-01-01

Presents results of a study examining the comparative effects of school (system) determinants on the educational careers of minority students in the Netherlands, drawing on rational choice and empowerment theories. Results indicate the importance of a school policy aimed at improving minority student achievement. Pull-out programs are detrimental,…

Bullying Risk in Children with Learning Difficulties in Inclusive Educational Settings

ERIC Educational Resources Information Center

Luciano, Severina; Savage, Robert S.

2007-01-01

This study investigated whether students with learning difficulties (LDs) attending inclusive schools that eschewed segregated "pull out" programs reported more incidents of being bullied than their peers without LDs. Cognitive and self-perception factors associated with reports of peer victimization were also explored. Participants were…

Peeling off the Elitist Label: Smart Politics.

ERIC Educational Resources Information Center

Peterson, Jean

1993-01-01

A high school teacher describes efforts to develop a comprehensive gifted education program while recognizing political realities. The program emphasized use of before-school and after-school periods rather than pull-out, addressed the burdens rather than blessings of high capability, focused on the underachieving gifted, and tried to avoid…

Food Pyramids and Bio-Accumulation.

ERIC Educational Resources Information Center

Baker, Valerie

1998-01-01

Students learn about marine food chains, bioaccumulation, the energy pyramid, and potential ocean pollutants and their effects on ocean ecosystems in this activity which involves having students pull drawings of marine organisms which include diatoms, copepods, anchovies, bonito, and killer whale out of a bag, then demonstrating the food chain by…

Examining Response to Intervention (RTI) Models in Secondary Education

ERIC Educational Resources Information Center

Epler, Pam, Ed.

2015-01-01

Response to Intervention (RTI) is an intervention model designed to assist all students regardless of their academic ability. It seeks to assist students who are struggling in academics by providing them with targeted assistance in the form of tutoring, pull-out services, and differentiated classroom instruction. "Examining Response to…

Public Schooling in Southeast Wisconsin: 2013-2014 [Summary

ERIC Educational Resources Information Center

Yeado, Joe; Schmidt, Jeff; Hart, Rebecca; Henken, Rob

2014-01-01

This summary from the "Public Schooling in Southeast Wisconsin: 2013-2014" full report presents the school district performance in a pull-out format. Definitions are provided for the column heading: (1) Total Operations Spending, (2) Property Tax Revenue, (3) Total Enrollment; (4) One-Year Change in Enrollment, (5) Minority Enrollment,…

The Best-Laid Plans

ERIC Educational Resources Information Center

Moberg, Lisa

2015-01-01

Despite having a classroom management plan in place when the year begins, teachers will encounter instances when student behavior blows up. The author discusses what to do when a student has a meltdown or in the aftermath of a fistfight when students are pulled out of class to deal with the consequences.

Pulling out All the Stops

ERIC Educational Resources Information Center

Sezer, Renan

2010-01-01

This article discusses how an active learning environment was created in a community college class and a high school mathematics class using the same approach. In both settings the NCTM and AMATYC Standards, such as problem solving, communication, use of technology and alternate assessment, were fully embraced. The goal was to have students take…

Intraoperative Physical Examination for Diagnosis of Interosseous Ligament Rupture-Cadaveric Study.

PubMed

Kachooei, Amir Reza; Rivlin, Michael; Wu, Fei; Faghfouri, Aram; Eberlin, Kyle R; Ring, David

2015-09-01

To study the intraobserver and interobserver reliability of the diagnosis of interosseous ligament (IOL) rupture in a cadaver model. On 12 fresh frozen cadavers, radial heads were cut using an identical incision and osteotomy. After randomization, the soft tissues of the limbs were divided into 4 groups: both IOL and triangular fibrocartilage (TFCC) intact; IOL disruption but TFCC intact; both IOL and TFCC divided; and IOL intact but TFCC divided. All incisions had identical suturing. After standard instruction and demonstration of radius pull-push and radius lateral pull tests, 10 physician evaluators with different levels of experience examined the cadaver limbs in a standardized way (elbow at 90° with the forearm held in both supination and pronation) and were asked to classify them into one of the 4 groups. Next, the same examiners were asked to re-examine the limbs after randomly changing the order of examination. The interobserver reliability of agreement for the diagnosis of IOL injury (groups 2 and 3) was fair in both rounds of examination and the intraobserver reliability was moderate. The intra- and interobserver reliabilities of agreement for the 4 groups of injuries among the examiners were fair in both rounds of examination. The sensitivity, specificity, accuracy, positive, and negative predictive values were all around 70%. The likelihood of a positive test corresponding with the presence of IOL rupture (positive likelihood ratio) was 2.2. The likelihood of a negative test correctly diagnosing an intact IOL was 0.40. In cadavers, intraoperative tests had fair reliability and 70% accuracy for the diagnosis of IOL rupture using the push-pull and lateral pull maneuvers. The level of experience did not have any effect on the correct diagnosis of intact versus disrupted IOL. Although not common, some failure of surgeries for traumatic elbow fracture-dislocations is because of failure in timely diagnosis of IOL disruption. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Influence of different functionalization on mechanical and interface behavior of MWCNTs/NBR sealing composites

NASA Astrophysics Data System (ADS)

Li, Kun; Gu, Boqin

2017-04-01

Rubber sealants are key components in processing industries. Carbon nanotubes (CNTs), which are randomly dispersed in polymer, are able to generate exciting effects. Focusing on mechanical properties of composites and interface characteristic between the fillers and matrix, carrying out SEM, DMA and uniaxial tensile tests, the tensile strength of the composites with 4 phr (parts by weight per hundred parts of rubber) multiwalled carbon nanotubes (MWNTs) is obviously improved. MWNTs with different functionalization have different influence on the viscoelastic and mechanical properties of the composites. Results indicate that MWNTs-COOH are broken when composites fractured. While MWNTs, MWNTs-OH and MWNTs-NH2 are pulled out from the matrix because interface debonds under the tensile failure. The interfacial shear stress (IFSS) is about 4.7 MPa in composites. The glass transition temperature (T g) shifts higher temperatures compared to pure NBR (Acrylonitrile-butadiene Rubber). The presence of the nanotubes limite the movement of NBR macromolecules.

Sliding Wear Response of Nanostructured YSZ Suspension Plasma-Sprayed Coating

NASA Astrophysics Data System (ADS)

Kossman, S.; Chicot, D.; Decoopman, X.; Iost, A.; van Gorp, A.; Meillot, E.; Puchi-Cabrera, E. S.; Santana, Y. Y.; Staia, M. H.

2014-12-01

Nanostructured yttria-stabilized zirconia coatings for applications in high-temperature environments can be deposited by suspension plasma spraying (SPS) techniques. The present research has been conducted in order to study the sliding wear response of a SPS ZrO2-8% mol. Y2O3 coating (75 μm in thickness) deposited onto a Haynes 230 substrate, using pin-on-disc tests. Some of the coated samples were subsequently heat-treated for 1 h at 300 and 600 °C. Samples characterization prior and after the wear tests was carried out by SEM, EDS, XRD and optical profilometry techniques. Instrumented indentation was employed to determine elastic modulus and hardness. The results have shown that the as-sprayed and heat-treated samples experienced severe wear (10-13 m3/Nm) and the worst wear performance corresponded to the sample heat treated at 600 °C. Such a behavior could be related to both the structural changes that took place during heat treatment and the nature and level of the residual stresses in the coatings. In general, the morphologies of the wear tracks observed by SEM have shown a smoothing of the surface, brittle fracture, smearing and grain pull-out.

Study of interface influence on bending performance of CFRP with embedded optical fibers

NASA Astrophysics Data System (ADS)

Liu, Rong-mei; Liang, Da-kai

2008-11-01

Studies showed that the bending strength of composite would be affected by embedded optical fibers. Interface strength between the embedded optical fiber and the matrix was studied in this paper. Based on the single fiber pull out tests, the interfacial shear strength between the coating and the clad is the weakest. The shear strength of the optical fiber used in this study is near to 0.8MPa. In order to study the interfacial effect on bending property of generic smart structure, a quasi-isotropic composite laminates were produced from Toray T300C/ epoxy prepreg. Optical fibers were embedded within different orientation plies of the plates, with the optical fibers embedded in the same direction. Accordingly, five different types of plates were produced. Impact tests were carried out on the 5 different plate types. It is shown that when the fiber was embedded at the upper layer, the bending strength drops mostly. The bending normal stress on material arrives at the maximum. So does the normal stress applied on the optical fiber at the surface. Therefore, destructions could originate at the interface between the coating and the clad foremost. The ultimate strength of the smart structure will be affected furthest.

Conditional Random Fields for Activity Recognition

DTIC Science & Technology

2008-04-01

final match. The final is never used as a training or hold out set. Table 4.1 lists the roles of the CMDragons’07 robot soccer team. The role of Goalie ...is not included because the goalie never changes roles. The classification task, which we formalize below, is to recognize robot roles from the avail...process and pull out the key information from the sensor data. Furthermore, as conditional models, CRFs do not waste modeling effort on the observations

Debunking the Myth of the Strategic Corporal

DTIC Science & Technology

2015-04-13

detainee abuse spiraled out of controL Detainees were stripped naked , forced to masturbate, were knocked out by closed hand punches to the temples, and...including Green and Barker, disguised themselves and headed on foot to a house where they previously observed a young Iraqi girl . The four soldiers...entered the family’s home and forced them all into a bedroom. One soldier grabbed the fourteen-year-old Iraqi girl and pulled her into the living

Energy requirements of tire pulling.

PubMed

Fredriksen, Per M; Mamen, Asgeir

2017-10-01

We have investigated the effect using walking poles and pulling tires at 4 and 6 km·h-1 (1.11 and 1.67 m·s-1) speeds on oxygen uptake (V̇O2) and heart rate. Eleven subjects, 6 males, with a mean (SD) age of 25.2 (6.9) years participated in field tests involving walking without poles, walking with poles and tire pulling with poles. Increasing the load caused the largest increases in energy demand, more than 4 MET. Speed increase also caused substantial energy increase, approximately 4 MET. Increasing the inclination only modestly increased the oxygen uptake, approximately 2 MET. In both level walking and uphill walking, using poles marginally increased oxygen uptake compared to working without poles. Pulling one tire (12.5 kg) required an oxygen uptake of 27 (4) mL·kg-1·min-1 at 4 km·h-1 and 0% inclination. Adding one more tire (6 kg) drove the oxygen uptake further up to 39 (4) mL·kg-1·min-1. This is close to the requirement of level running at 10.5 km·h-1. Pulling both tires at 6 km·h-1 and 5% inclination required a V̇O2 of 54 (6) mL·kg-1·min-1, equal to running uphill at 5% inclination and 12.5 km·h-1 speed. Heart rate rose comparably with oxygen uptake. At 4 km·h-1 and 0% inclination the increase was 29 bpm, from 134 (21) to 163 (22) bpm when going from pulling one tire to two tires. In the hardest exercise, 6 km·h-1 and 5% inclination, heart rate reached 174 (14) bpm. The study showed that tire pulling even at slow speeds has an energy requirement that is so large that the activity may be feasible as endurance training.

KSC-2014-3668

NASA Image and Video Library

2014-08-25

CAPE CANAVERAL, Fla. – The umbilical swing arm for Orion's Exploration Flight Test 1, or EFT-1, has been attached to the uppermost location on the fixed umbilical tower at Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida. The swing arm is undergoing a test to confirm that it is operating correcting. During the test, the arm was swung out and closer to the Vertical Integration Facility at the pad. The uppermost swing arm will carry umbilicals that will be mated to Orion's launch abort system and environmental control system. During launch, all three umbilicals will pull away from Orion and the United Launch Alliance Delta IV Heavy rocket at T-0. During the EFT-1 mission, Orion will travel farther into space than any human spacecraft has gone in more than 40 years. The data gathered during the flight will influence design decisions, validate existing computer models and innovative new approaches to space systems development, as well as reduce overall mission risks and costs for later Orion flights. Liftoff of Orion on its first flight test is planned for fall 2014. Photo credit: NASA/Daniel Casper

Improved Tensile Test for Ceramics

NASA Technical Reports Server (NTRS)

Osiecki, R. A.

1982-01-01

For almost-nondestructive tensile testing of ceramics, steel rod is bonded to sample of ceramic. Assembly is then pulled apart in conventional tensile-test machine. Test destroys only shallow surface layer which can be machined away making specimen ready for other uses. Method should be useful as manufacturing inspection procedure for low-strength brittle materials.

Steering Performance, Tactical Vehicles

DTIC Science & Technology

2015-07-29

5 4.1 General Vehicle and Test Characterization ........................... 5 4.2 Weave Test...able to be driven in a straight line without steer input (i.e., “ hands free”). If the vehicle pulls in either direction, the alignment should be...Evaluation Center (AEC) prior to using military personnel as test participants. 4. TEST PROCEDURES. 4.1 General Vehicle and Test

The effect of denture cleansing solutions on the retention of pink locator attachments after multiple pulls: an in vitro study.

PubMed

You, Wenguang; Masri, Radi; Romberg, Elaine; Driscoll, Carl F; You, Tao

2011-08-01

The effect of denture cleansing solutions and multiple pulls on the retention of pink Locator patrices was studied. Five groups of pink Locator attachments (3.0 lb. Light Retention replacement patrix attachments; five in each group) were soaked for the equivalent of 6 months of clinical use in the following solutions: water (control), Efferdent, Polident Overnight, 6.15% sodium hypochlorite (NaOCL, 1:10 dilution), and Listerine mouthwash. A universal testing machine set at a 2 in/min crosshead speed was used to perform 548 pulls (548 cycles of insertion and removal). The reduction in load to dislodgement (retention) after the initial pull and the final pull and the percent reduction in retention after 6 months were compared between the groups using a one-way ANOVA followed by Tukey's Honestly Significant Difference (HSD) Test (α= 0.05). Denture cleansing solutions significantly reduced the retentive values of pink Locator attachments after the initial pull (F = 17.435, p < 0.0001). The retentive values of Efferdent, Listerine, Polident Overnight, and water were significantly higher than the retentive value of the attachments soaked in NaOCl. After 6 months of simulated use (548 pulls), the four denture cleansing solutions had significant effects on the retentive values of pink Locator attachments (F = 5.855, p = 0.003). The retentive values for attachments soaked in NaOCl (7.29 ± 1.0 N) were significantly lower than those of attachments soaked in Listerine (15.82 ± 4.7 N) and in Polident Overnight (14.41 ± 3.6 N). These cleansing solutions also had a significant effect on the percentage of retention lost (F = 3.271, p = 0.032). The loss of retention in attachments soaked in Listerine (29 ± 9%) was significantly lower than attachments soaked in water (53 ± 12%). The loss of retention in attachments soaked in Efferdent was 49 ± 9%; in Polident Overnight, 34 ± 18%; and in NaOCl, 42 ± 11%. There was no significant difference in the percentage of retention loss between water, Efferdent, NaOCl, and Polident Overnight. There was also no significant difference in the percentage of retention loss between Efferdent, NaOCl, Polident Overnight, and Listerine. NaOCl significantly decreased the retentive value of Locators. Therefore, it should not be routinely recommended for use as a denture cleanser. Listerine significantly increased the retention of the Locator attachments; however, it is premature to recommend Listerine for use as a denture cleanser. © 2011 by The American College of Prosthodontists.

An experimental investigation of silicon wafer surface roughness and its effect on the full strength of plated metals

NASA Technical Reports Server (NTRS)

Spiers, G. D.

1981-01-01

Plated silicon wafers with surface roughness ranging from 0.4 to 130 microinches were subjected to tensile pull strength tests. Electroless Ni/electroless Cu/electroplated Cu and electroless Ni/electroplated Cu were the two types of plate contacts tested. It was found that smoother surfaces had higher pull strength than rougher, chemically etched surfaces. The presence of the electroless Cu layer was found to be important to adhesion. The mode of fracture of the contact as it left the silicon was studied, and it was found that in almost all cases separation was due to fracture of the bulk silicon phase. The correlation between surface roughness and mode of contact failure is presented and interpreted.

Test equipment data package for the KC-135 fiber pulling apparatus

NASA Technical Reports Server (NTRS)

Kosten, Sue; Smith, Guy A.; Workman, Gary; Tucker, Dennis

1991-01-01

The Fiber Pulling Apparatus (FPA) is a device designed to produce continuous glass fibers from simulated lunar soil, and to determine the effects of reduced gravity, specifically 1/6 g on fiber formation and resultant properties. Briefly, pre-melt simulated lunar soil will be placed in a pint crucible and heated to 1200 C or higher, up to a maximum temperature of 1400 C. At a given temperature, a quartz fiber will be immersed into the melt and then pulled through a chill block and wound onto a cylindrical bobbin using a servo motor control. A high resolution video camera will record the fiber as it is being pulled. This assembly wil be enclosed in Plexiglas. Before fiber pulling commences, the apparatus will be backfilled with dry nitrogen. A separate data acquisition system will support this apparatus. This system will contain a personal computer, video recorder, and monitor. Temperature, acceleration, winding speed, and video images will be controlled and recorded using the data acquisition system. Thus, the FPA will consist of two hardware packages, the fiber production assembly and the data acquisition rack. The primary objective of this test is to determine the effects of 1/6 g on the formation of continuous glass fiber made from simulated lunar soil. Baseline studies using the FPA on the ground will provide a reference for the 1/6 g studies. Of particular interest will be the effect of 1/6 g on the free fluid zone where the fiber exits the crucible. In the fiber spinning parlance this zone is known as the upper jet region, where the boundary slope is greater than one tenth. The properties of the resulting glass fiber will depend on the jet shape as well as distributions of velocity, temperature and tension within the jet. It is unknown at this time how 1/6 g will effect these parameters.

Rigging Test Bed Development for Validation of Multi-Stage Decelerator Extractions

NASA Technical Reports Server (NTRS)

Kenig, Sivan J.; Gallon, John C.; Adams, Douglas S.; Rivellini, Tommaso P.

2013-01-01

The Low Density Supersonic Decelerator project is developing new decelerator systems for Mars entry which would include testing with a Supersonic Flight Dynamics Test Vehicle. One of the decelerator systems being developed is a large supersonic ringsail parachute. Due to the configuration of the vehicle it is not possible to deploy the parachute with a mortar which would be the preferred method for a spacecraft in a supersonic flow. Alternatively, a multi-stage extraction process using a ballute as a pilot is being developed for the test vehicle. The Rigging Test Bed is a test venue being constructed to perform verification and validation of this extraction process. The test bed consists of a long pneumatic piston device capable of providing a constant force simulating the ballute drag force during the extraction events. The extraction tests will take place both inside a high-bay for frequent tests of individual extraction stages and outdoors using a mobile hydraulic crane for complete deployment tests from initial pack pull out to canopy extraction. These tests will measure line tensions and use photogrammetry to track motion of the elements involved. The resulting data will be used to verify packing and rigging as well, as validate models and identify potential failure modes in order to finalize the design of the extraction system.

A push-pull system to reduce house entry of malaria mosquitoes

PubMed Central

2014-01-01

Background Mosquitoes are the dominant vectors of pathogens that cause infectious diseases such as malaria, dengue, yellow fever and filariasis. Current vector control strategies often rely on the use of pyrethroids against which mosquitoes are increasingly developing resistance. Here, a push-pull system is presented, that operates by the simultaneous use of repellent and attractive volatile odorants. Method/Results Experiments were carried out in a semi-field set-up: a traditional house which was constructed inside a screenhouse. The release of different repellent compounds, para-menthane-3,8-diol (PMD), catnip oil e.o. and delta-undecalactone, from the four corners of the house resulted in significant reductions of 45% to 81.5% in house entry of host-seeking malaria mosquitoes. The highest reductions in house entry (up to 95.5%), were achieved by simultaneously repelling mosquitoes from the house (push) and removing them from the experimental set-up using attractant-baited traps (pull). Conclusions The outcome of this study suggests that a push-pull system based on attractive and repellent volatiles may successfully be employed to target mosquito vectors of human disease. Reductions in house entry of malaria vectors, of the magnitude that was achieved in these experiments, would likely affect malaria transmission. The repellents used are non-toxic and can be used safely in a human environment. Delta-undecalactone is a novel repellent that showed higher effectiveness than the established repellent PMD. These results encourage further development of the system for practical implementation in the field. PMID:24674451

Pushing Back against Push-In: ESOL Teacher Resistance and the Complexities of Coteaching

ERIC Educational Resources Information Center

McClure, Greg; Cahnmann-Taylor, Melisa

2010-01-01

As U. S. school districts struggle to address persistent achievement gaps between increasing numbers of English language learners (ELLs) and their native-English-speaking counterparts, many districts are moving away from segregative models like pull-out to implement more collaborative approaches such as coteaching, or push-in. In contrast to…

The Gift of Two Languages: A Spanish Immersion Program Brings Government Hill Elementary Back from the Brink.

ERIC Educational Resources Information Center

Blankenship, Judy

2002-01-01

An Anchorage (Alaska) elementary school serving low-income minority groups revitalized itself by starting a dual-language (Spanish/English) immersion program. Pull-out programs were coordinated using instructional and tutoring teams, quality professional development was provided, bilingualism was fostered for all students, and parent participation…

Using Strategic Communications to Address Critical Threats to Border Security

DTIC Science & Technology

2009-04-01

Frequency Identification in November of 2008. This technology forces people to hold up their identification card to an electronic scanner before they pull...podcasts via Texas A&Ms iTunes University to reach out to a greater number of people. Because radio remains a part of the American way of life, it

Student, Teacher, and Parent Preference for Less Restrictive Special Education Models--Cooperative Teaching.

ERIC Educational Resources Information Center

Walsh, James M.

This study investigated the preferences of parents, teachers, and students regarding the relative benefits of a cooperative teaching (general educator/special educator in a general education classroom) service model in comparison to a special education "pull-out" model. A cooperative teaching model was implemented in four public…

Multiple Perspectives on Hiroshima. Pull-out 2.

ERIC Educational Resources Information Center

Schill, Karen

1998-01-01

Summarizes a unit of study in which students learn about the bombing of Hiroshima and Nagasaki through reading about the survivors of the atomic bomb explosions and reflecting on the debate surrounding the 50th anniversary commemorations in Hiroshima (Japan) and the United States. Suggests that students keep journals throughout the unit. (CMK)

Staying Afloat in New Orleans

ERIC Educational Resources Information Center

Terry, Dorothy Givens

2007-01-01

Following the second anniversary of Hurricane Katrina, most of the attention in New Orleans is still on physical and facility recovery efforts. But buried beneath the news accounts of a city trying to pull itself out of its debris are groups and organizations whose physical infrastructures may not have taken a direct hit from Katrina, but whose…

Stop/Start: Overview

Science.gov Websites

/Start technology conserves energy by shutting off the gasoline engine when the vehicle is at rest, such as at a traffic light, and automatically re-starting it when the driver pushes the gas pedal to go engine when pulling out from a stop and generating electricity which is stored in the battery. Main stage

Jordanian Children in the Eye of the Storm.

ERIC Educational Resources Information Center

United Nations Educational, Scientific and Cultural Organization, Amman (Jordan). Regional Office for the Middle East and North Africa.

The Gulf Crisis that erupted in August, 1990 brought Jordan widespread economic devastation, increased poverty, the threat of hunger, health setbacks, and other hardships. Just as the country's economy was beginning to pull out of a lingering recession, Jordan was struck by the economic embargo against Iraq, the influx of over a million evacuees…

Computer Assisted Mathematics Prescription Learning Pull-out Program in an Elementary School.

ERIC Educational Resources Information Center

Swarm, Christine C.

Summaries of recent research have found computer-assisted instruction to be a highly motivating method of instruction that fosters independent study and provides for the immediate feedback necessary for the encouragement of individualized learning. A nonexperimental study was conducted with fourth, fifth, and sixth grade students (n=88) in a…

How Can I Make Social Studies Move? Pull-out 2.

ERIC Educational Resources Information Center

Nilges, Lynda M.; Gallavan, Nancy P.

1998-01-01

Suggests a four-stage framework that teachers can use to integrate creative dance into the social studies curriculum. Discusses the four stages through the use of a sample dance about tornadoes that complements a thematic social studies unit about the impact of weather and natural disasters upon people and their environments. (CMK)

Like a Rock: Far Rockaway High School

ERIC Educational Resources Information Center

Whelan, Debra Lau

2007-01-01

Students from Far Rockaway High School are just back from spring break, and media specialist Geri Ellner is busy getting ready for her first class. She's already pulled out a copy of Anthony Browne's award-winning picture book "The Shape Game" (Farrar, 2003), and now she's patiently cuing up a Disney video of "Pocahontas" on…

A New Approach to Business Partnerships

ERIC Educational Resources Information Center

Ghysels, Maurice; Thibodeaux, Kathy

2006-01-01

Beyond the need for many school districts to pull out of the death spiral of declining enrollment, educational leaders throughout California must foster a culture of change and accelerate creative self-renewal to provide students with an education for the world ahead. Businesses demand and expect much more from public education as the global…

Assisting Parents of Bilingual Students to Achieve Equity in Public Schools

ERIC Educational Resources Information Center

Ochoa, Salvador Hector; Rhodes, Robert L.

2005-01-01

This article provides school-based consultants with an overview of the English language learner (ELL) student population and common programs available to ELL students (such as English-only programs, pull-out English as a second language [ESL], content-based ESL, transitional bilingual programs, maintenance bilingual programs, and two-way or dual…

Famous Americans: George Washington and Abraham Lincoln.

ERIC Educational Resources Information Center

Fleming, Maria

This book provides background information and ideas for teaching about George Washington and Abraham Lincoln at the primary grade level. Cross-curricular activities include work in music, writing, art, research, plays, and games. A pull-out poster with a poem on "President's Day" is stapled in the center of the book. Chapters in the book…

Spicing up Classrooms Using Creative Challenges

ERIC Educational Resources Information Center

Rubenstein, Lisa DaVia; Wilson, Hope E.

2011-01-01

Gifted programs have long relied upon creative challenges (activities in which students are asked to create a product or an idea in response to specific teacher directions) to spark ideas, collaboration, and exploration. These challenges, however, have often been devoid of context. Gifted students are pulled out of the classroom to build a bridge…

Managing the Enrollment Boom

ERIC Educational Resources Information Center

Carr, Coeli

2009-01-01

As the nation works through a lingering recession, community colleges are pulled in two very different directions. On one hand is opportunity, as skyrocketing numbers of students--some right out of high school, others eager to retool old skills or immerse themselves in new job-enhancement training--beat a path to their doors. On the other is…

Clinical results of the re-fixation of a Chevron olecranon osteotomy using an intramedullary cancellous screw and suture tension band.

PubMed

Wagener, Marc L; Dezillie, Marleen; Hoendervangers, Yvette; Eygendaal, Denise

2015-04-01

Exposure of the distal humerus in case of an articular fracture is often performed through a Chevron osteotomy of the olecranon. Several options have been described for re-fixation of the Chevron osteotomy. Pull-out of the hard-wear is often seen as complication. In this study, an evaluation of the re-fixation of the Chevron osteotomy through a cancellous screw and suture tension band was performed. The data of 19 patients in whom a Chevron osteotomy was re-fixated with a cancellous screw in combination with a suture tension band were used. Evaluation was performed by assessment of the post-operative X-rays and documentation of complications. In all 19 cases, evaluation of the post-operative X-rays showed complete consolidation without dislocation or other complications. Re-fixation of a Chevron osteotomy of the olecranon with a large cancellous screw with a suture tension band provides adequate stability to result in proper healing of the osteotomy in primary cases when early post-operative mobilisation is allowed. Complications as pull-out of the hard-wear were not reported.

Emergence of a dark force in corpuscular gravity

NASA Astrophysics Data System (ADS)

Cadoni, M.; Casadio, R.; Giusti, A.; Tuveri, M.

2018-02-01

We investigate the emergent laws of gravity when dark energy and the de Sitter space-time are modeled as a critical Bose-Einstein condensate of a large number of soft gravitons NG. We argue that this scenario requires the presence of various regimes of gravity in which NG scales in different ways. Moreover, the local gravitational interaction affecting baryonic matter can be naturally described in terms of gravitons pulled out from this dark energy condensate (DEC). We then explain the additional component of the acceleration at galactic scales, commonly attributed to dark matter, as the reaction of the DEC to the presence of baryonic matter. This additional dark force is also associated to gravitons pulled out from the DEC and correctly reproduces the modified Newtonian dynamics (MOND) acceleration. It also allows for an effective description in terms of general relativity sourced by an anisotropic fluid. We finally calculate the mass ratio between the contribution of the apparent dark matter and the baryonic matter in a region of size r at galactic scales and show that it is consistent with the Λ CDM predictions.

The role of calcium and magnesium in the concrete tubes of the sandcastle worm.

PubMed

Sun, ChengJun; Fantner, Georg E; Adams, Jonathan; Hansma, Paul K; Waite, J Herbert

2007-04-01

Sandcastle worms Phragmatopoma californica build mound-like reefs by sticking together large numbers of sand grains with cement secreted from the building organ. The cement consists of protein plus substantial amounts of calcium and magnesium, which are not invested in any mineral form. This study examined the effect of calcium and magnesium depletion on the structural and mechanical properties of the cement. Divalent ion removal by chelating with EDTA led to a partial collapse of cement architecture and cement dislodgement from silica surfaces. Mechanical properties examined were sand grain pull-out force, tube resistance to compression and cement adhesive force. EDTA treatment reduced sand grain pull-out forces by 60% and tube compressive strength by 50% relative to controls. EDTA lowered both the maximal adhesive force and energy dissipation of cement by up to an order of magnitude. The adhesiveness of calcium- and magnesium-depleted cement could not be restored by re-exposure to the ions. The results suggest that divalent ions play a complex and multifunctional role in maintaining the structure and stickiness of Phragmatopoma cement.

Rubble masonry response under cyclic actions: The experience of L’Aquila city (Italy)

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

Fonti, Roberta, E-mail: roberta.fonti@tum.de; Barthel, Rainer, E-mail: r.barthel@lrz.tu-muenchen.de; Formisano, Antonio, E-mail: antoform@unina.it

2015-12-31

Several methods of analysis are available in engineering practice to study old masonry constructions. Two commonly used approaches in the field of seismic engineering are global and local analyses. Despite several years of research in this field, the various methodologies suffer from a lack of comprehensive experimental validation. This is mainly due to the difficulty in simulating the many different kinds of masonry and, accordingly, the non-linear response under horizontal actions. This issue can be addressed by examining the local response of isolated panels under monotonic and/or alternate actions. Different testing methodologies are commonly used to identify the local responsemore » of old masonry. These range from simplified pull-out tests to sophisticated in-plane monotonic tests. However, there is a lack of both knowledge and critical comparison between experimental validations and numerical simulations. This is mainly due to the difficulties in implementing irregular settings within both simplified and advanced numerical analyses. Similarly, the simulation of degradation effects within laboratory tests is difficult with respect to old masonry in-situ boundary conditions. Numerical models, particularly on rubble masonry, are commonly simplified. They are mainly based on a kinematic chain of rigid blocks able to perform different “modes of damage” of structures subjected to horizontal actions. This paper presents an innovative methodology for testing; its aim is to identify a simplified model for out-of-plane response of rubbleworks with respect to the experimental evidence. The case study of L’Aquila district is discussed.« less

Influence of heat-treated Al-Si coating on the weldability and microstructural inhomogeneity for hot stamped steel resistance nut projection welds

NASA Astrophysics Data System (ADS)

Chun, Eun-Joon; Lim, Sung-Sang; Kim, Young-Tae; Nam, Ki-Sung; Kim, Young-Min; Park, Young-Whan; Murugan, Siva Prasad; Park, Yeong-Do

2018-03-01

Resistance nut projection weldability of Al-Si coated hot stamped steel (HSS) was investigated under the viewpoint of weldable current range and joint strength (pull-out load). The microstructural inhomogeneities in the welds were also studied in order to elucidate the factors affecting the joint strength of the welds. The weldability of the given Al-Si coated HSS was compared with the weldability of an identical HSS without the Al-Si coating (Al-Si coating was polished out) and Zn coated dual phase steel. The weldable current range of Al-Si coated HSS was found to be narrower than that of the other materials. Furthermore, the average pull-out load within the weldable current range of the Al-Si coated HSS was the lowest among the three materials. The reason for poor weld mechanical property of the Al-Si coated hot-stamped steel was attributed to the microstructural inhomogeneities such as unmixed Al-Si coating layer at the edge of the nugget and the second phase Fe3(Al, Si) intermetallic compound. The formation of Fe3(Al, Si) phase was attributed to the solidification segregation of Al and Si during the weld solidification and was confirmed with the numerical analysis of solidification segregation.

Development of radon-222 as a natural tracer for monitoring the remediation of NAPL contamination in the subsurface. 1998 annual progress report

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

Semprini, L.; Istok, J.

'The objective of this research is to develop a unique method of using naturally occurring radon-222 as a tracer for locating and quantitatively describing the presence of subsurface NAPL contamination. The research will evaluate using radon as an inexpensive, yet highly accurate, means of detecting NAPL contamination and assessing the effectiveness of NAPL remediation. Laboratory, field, and modeling studies are being performed to evaluate this technique, and to develop methods for its successful implementation in practice. This report summarizes work that has been accomplished after 1-year of a 3-year project. The research to date has included radon tracer tests inmore » physical aquifer models (PAMs) and field studies at Site 300 of the Lawrence Livermore National Laboratory, CA, and Site 100D at Hanford DOE Facility, WA. The PAM tests have evaluated the ability of radon as a tracer to monitor the remediation of TCE NAPL contamination using surfactant treatment, and oxidation with permanganate. The surfactant tests were performed in collaboration with Dr. Jack Istok and Dr. Jennifer Field and their EMSP project ``In-situ, Field-Scale Evaluation of Surfactant Enhanced DNAPL Recovery Using a Single-Well-Push-Pull Test.'''' This collaboration enabled the EMSP radon project to make rapid progress. The PAM surfactant tests were performed in a radial flow geometry to simulate the push-pull-method that is being developed for surfactant field tests. The radon tests were easily incorporated into these experiments, since they simply rely on measuring the natural radon present in the subsurface fluids. Two types of radon tests were performed: (1) static tests where radon was permitted to build-up to steady-state concentrations in the pore fluids and the groundwater concentrations were monitored, and (2) dynamic tests were the radon response during push-pull surfactant tests was measured. Both methods were found to be useful in determining how NAPL remediation was progressing.'« less

Serial dependence promotes object stability during occlusion

PubMed Central

Liberman, Alina; Zhang, Kathy; Whitney, David

2016-01-01

Object identities somehow appear stable and continuous over time despite eye movements, disruptions in visibility, and constantly changing visual input. Recent results have demonstrated that the perception of orientation, numerosity, and facial identity is systematically biased (i.e., pulled) toward visual input from the recent past. The spatial region over which current orientations or face identities are pulled by previous orientations or identities, respectively, is known as the continuity field, which is temporally tuned over the past several seconds (Fischer & Whitney, 2014). This perceptual pull could contribute to the visual stability of objects over short time periods, but does it also address how perceptual stability occurs during visual discontinuities? Here, we tested whether the continuity field helps maintain perceived object identity during occlusion. Specifically, we found that the perception of an oriented Gabor that emerged from behind an occluder was significantly pulled toward the random (and unrelated) orientation of the Gabor that was seen entering the occluder. Importantly, this serial dependence was stronger for predictable, continuously moving trajectories, compared to unpredictable ones or static displacements. This result suggests that our visual system takes advantage of expectations about a stable world, helping to maintain perceived object continuity despite interrupted visibility. PMID:28006066

Hartwell Lake Project, Savannah River, Georgia and South Carolina. Rehabilitation of Clemson Upper Diversion Dam. Construction Foundation Report. Volume 2. Appendices B thru E

DTIC Science & Technology

1989-08-01

remove by gravity -washed out 585.8 i -- 89. 2 gneiss from inner - ibarrel Bottom of hole 89.2’ Tape depth 89.0’ 90 -0 I-Note: 6-7-84 water level after...barrel and5 _-_89.3 washed all meterial Bottom of hole 89.3’ left in outer barrel- 90 out of barrel befor- drilling for pull I Tape depth 89.0’ Note

Non-Back-Drivable, Freewheeling Coupling

NASA Technical Reports Server (NTRS)

Llewellin, W.

1986-01-01

Cables reeled in and out with less risk of tangling. Opposing teeth engage with clockwise rotation and disengage with clockwise rotation of crank. Driving plate moves axially with respect to driven plate on ball points to engage and disengage. Clutch developed for reeling and unreeling tether line used to link astronaut to space vehicle. Allows line pulled out freely and helps to prevent line from tangling in reel housing when crank is turned backward. New clutch concept also applicable to fishing reels, toys, and safety-line mechanisms.

U.S. Army Rifle and Carbine Adoption between 1865 and 1900

DTIC Science & Technology

2007-06-15

end-strength of 11,043. General in Chief of the Army General Ulysses S. Grant wanted to increase the Regular Army to 80,000 men , but neither...the weapon to stand. The shooter placed a primer on the nipple and cocked the hammer making the arm ready to fire. When the shooter pulled the...another change to the barrel bands, setting the nipple bolster out a bit further, incorporating a clean out screw instead of an angled flash hole, and

Forced reptation revealed by chain pull-out simulations.

PubMed

Bulacu, Monica; van der Giessen, Erik

2009-08-14

We report computation results obtained from extensive molecular dynamics simulations of tensile disentanglement of connector chains placed at the interface between two polymer bulks. Each polymer chain (either belonging to the bulks or being a connector) is treated as a sequence of beads interconnected by springs, using a coarse-grained representation based on the Kremer-Grest model, extended to account for stiffness along the chain backbone. Forced reptation of the connectors was observed during their disentanglement from the bulk chains. The extracted chains are clearly seen following an imaginary "tube" inside the bulks as they are pulled out. The entropic and energetic responses to the external deformation are investigated by monitoring the connector conformation tensor and the modifications of the internal parameters (bonds, bending, and torsion angles along the connectors). The work needed to separate the two bulks is computed from the tensile force induced during debonding in the connector chains. The value of the work reached at total separation is considered as the debonding energy G. The most important parameters controlling G are the length (n) of the chains placed at the interface and their areal density. Our in silico experiments are performed at relatively low areal density and are disregarded if chain scission occurs during disentanglement. As predicted by the reptation theory, for this pure pull-out regime, the power exponent from the scaling G proportional, variant n(a) is a approximately 2, irrespective of chain stiffness. Small variations are found when the connectors form different number of stitches at the interface, or when their length is randomly distributed in between the two bulks. Our results show that the effects of the number of stitches and of the randomness of the block lengths have to be considered together, especially when comparing with experiments where they cannot be controlled rigorously. These results may be significant for industrial applications, such reinforcement of polymer-polymer adhesion by connector chains, when incorporated as constitutive laws at higher time/length scales in finite element calculations.

Biomechanical evaluation of a new fixation device for the thoracic spine.

PubMed

Hongo, Michio; Ilharreborde, Brice; Gay, Ralph E; Zhao, Chunfeng; Zhao, Kristin D; Berglund, Lawrence J; Zobitz, Mark; An, Kai-Nan

2009-08-01

The technology used in surgery for spinal deformity has progressed rapidly in recent years. Commonly used fixation techniques may include monofilament wires, sublaminar wires and cables, and pedicle screws. Unfortunately, neurological complications can occur with all of these, compromising the patients' health and quality of life. Recently, an alternative fixation technique using a metal clamp and polyester belt was developed to replace hooks and sublaminar wiring in scoliosis surgery. The goal of this study was to compare the pull-out strength of this new construct with sublaminar wiring, laminar hooks and pedicle screws. Forty thoracic vertebrae from five fresh frozen human thoracic spines (T5-12) were divided into five groups (8 per group), such that BMD values, pedicle diameter, and vertebral levels were equally distributed. They were then potted in polymethylmethacrylate and anchored with metal screws and polyethylene bands. One of five fixation methods was applied to the right side of the vertebra in each group: Pedicle screw, sublaminar belt with clamp, figure-8 belt with clamp, sublaminar wire, or laminar hook. Pull-out strength was then assessed using a custom jig in a servohydraulic tester. The mean failure load of the pedicle screw group was significantly larger than that of the figure-8 clamp (P = 0.001), sublaminar belt (0.0172), and sublaminar wire groups (P = 0.04) with no significant difference in pull-out strength between the latter three constructs. The most common mode of failure was the fracture of the pedicle. BMD was significantly correlated with failure load only in the figure-8 clamp and pedicle screw constructs. Only the pedicle screw had a statistically significant higher failure load than the sublaminar clamp. The sublaminar method of applying the belt and clamp device was superior to the figure-8 method. The sublaminar belt and clamp construct compared favorably to the traditional methods of sublaminar wires and laminar hooks, and should be considered as an alternative fixation device in the thoracic spine.

Biomechanical evaluation of a new fixation device for the thoracic spine

PubMed Central

Hongo, Michio; Ilharreborde, Brice; Zhao, Chunfeng; Zhao, Kristin D.; Berglund, Lawrence J.; Zobitz, Mark; An, Kai-Nan

2009-01-01

The technology used in surgery for spinal deformity has progressed rapidly in recent years. Commonly used fixation techniques may include monofilament wires, sublaminar wires and cables, and pedicle screws. Unfortunately, neurological complications can occur with all of these, compromising the patients’ health and quality of life. Recently, an alternative fixation technique using a metal clamp and polyester belt was developed to replace hooks and sublaminar wiring in scoliosis surgery. The goal of this study was to compare the pull-out strength of this new construct with sublaminar wiring, laminar hooks and pedicle screws. Forty thoracic vertebrae from five fresh frozen human thoracic spines (T5–12) were divided into five groups (8 per group), such that BMD values, pedicle diameter, and vertebral levels were equally distributed. They were then potted in polymethylmethacrylate and anchored with metal screws and polyethylene bands. One of five fixation methods was applied to the right side of the vertebra in each group: Pedicle screw, sublaminar belt with clamp, figure-8 belt with clamp, sublaminar wire, or laminar hook. Pull-out strength was then assessed using a custom jig in a servohydraulic tester. The mean failure load of the pedicle screw group was significantly larger than that of the figure-8 clamp (P = 0.001), sublaminar belt (0.0172), and sublaminar wire groups (P = 0.04) with no significant difference in pull-out strength between the latter three constructs. The most common mode of failure was the fracture of the pedicle. BMD was significantly correlated with failure load only in the figure-8 clamp and pedicle screw constructs. Only the pedicle screw had a statistically significant higher failure load than the sublaminar clamp. The sublaminar method of applying the belt and clamp device was superior to the figure-8 method. The sublaminar belt and clamp construct compared favorably to the traditional methods of sublaminar wires and laminar hooks, and should be considered as an alternative fixation device in the thoracic spine. PMID:19404687

Risks to human health and estuarine ecology posed by pulling out creosote-treated timber on oyster farms.

PubMed

Smith, Paul T

2008-01-31

Five oyster farms in Port Stephens, Australia were studied to identify consequences of using creosote-treated posts and the risks posed by removing the posts. Gas chromatography coupled with mass spectrometry (GC/MS) was used to measure polycyclic aromatic hydrocarbons (PAHs) and phenols in sediments, timber, water and oyster tissue. Before posts were removed, the total PAHs in surface sediment on farms was 24.1 mgkg(-1) dry weight. This increased to 45.5 mgkg(-1) dry weight after the posts were pulled out and remained significantly higher 6 months later at 59.7 mgkg(-1) dry weight. A similar increase was found in deeper sediments. The sediment attached to creosote-treated posts had a total concentration of PAHs of 484-2642 mgkg(-1) dry weight, while the corresponding value for the sediment on tar-treated posts was only 30.7 mgkg(-1) dry weight. The surface timber of creosote-treated posts had high levels of PAHs and an average post contained 43 g of PAHs. The total PAHs dispersed to the environment when a creosote-treated post was pulled out was at least 0.67 g. The main species were PAHs with low-molecular weights: fluoranthene, phenanthrene, pyrene, acenaphthylene and chrysene. Benzo(a)pyrene represented 1-10% of PAHs in most samples. Bioassays with creosote-contaminated sediment revealed that Sydney rock oysters (Saccostrea glomerate) and Pacific oysters (Crassostrea gigas) accumulated PAHs at (mgkg(-1) wet tissue weight): 11.3-15.3 and 35.5-47.9, respectively, when exposed for 5 days to water with < 1 microgl(-1) PAHs. Wild oysters growing on creosote-treated posts had high levels of phenols (0.09-6.92 mgkg(-1) wet weight) and PAHs (0.59-1.01 mgkg(-1) wet weight). The dilemma posed by removing creosote-treated posts and dispersing carcinogenic, bioavailable contaminants needs to be managed in light of risks to human health and estuarine ecology.

Lockheed P-38 Lightning in flight

NASA Technical Reports Server (NTRS)

1943-01-01

The P-38 shown in this photo was one of the fighters built in the late 1930s and early 1940s that experienced compressibility effects. In steep dives, these aircraft could reach speeds above Mach 0.75 (called transonic). At transonic speeds, air in front of the wings became compressed and reached supersonic speeds as it flowed over the wings, forming a shock wave. This resulted in an increase in drag and a decrease in lift. Another result was the movement of the wing's center of lift to the rear, forcing the aircraft to rotate so that the nose moved downward and it went into a steep dive. Pilots found that that their aircraft would not pull out of this dive. When they attempted to pull out, they found the control stick, as one pilot put it, 'was cast in about two feet of concrete.' In some cases, the airplanes crashed or broke up in the denser air as they approached the ground. In other cases, the pilots were able to pull out of the dive. These accidents and near misses reinforced the popular belief in a 'sound barrier.' The need for data at speeds near that of sound and the inability of wind tunnels at the time to provide it would lead to the construction and flight of the X-1 and D-558 research aircraft. The Lockheed P-38 Lightning was one of the best-known Army Air Forces fighters that flew in World War II. It was already in mass production before the war started for the United States, and production lasted until 1945. With a wingspan of 52 feet; a length of 37 feet, 10 inches; and a height of 9 feet, 10 inches, the P-38s had maximum speeds ranging from 390 miles per hour for the basic P-38 to 414 mph for the P-38L. Except for the M model (a two-seater), all the P-38s were single-seat pursuit and long-range escort aircraft.

16 CFR 1500.42 - Test for eye irritants.

Code of Federal Regulations, 2012 CFR

2012-01-01

... before testing, and only those animals without eye defects or irritation shall be used. The animal is held firmly but gently until quiet. The test material is placed in one eye of each animal by gently pulling the lower lid away from the eyeball to form a cup into which the test substance is dropped. The...

Study on cord/rubber interface at elevated temperatures by H-pull test method

NASA Astrophysics Data System (ADS)

Jamshidi, M.; Afshar, F.; Mohammadi, N.; Pourmahdian, S.

2005-08-01

Cords are used as reinforcing materials in rubber compounds. To increase cord/rubber interfacial adhesion, they are coated by an adhesive (usually based on resorcinol-formaldehyde-latex). These composites are used in many sectors such as tire and belt industries. Cord/rubber adhesion strength is an important aspect to determine the durability of system. Due to temperature increase during running tires, the adhesion energy becomes different from initial one. To study cord/rubber interface at elevated temperatures, H-adhesion test method was used. H-pull test is a simple method for adhesion evaluation at ambient temperature, so it is usually used for material quality control. In this research, cord/rubber systems were vulcanized at different temperatures and H-adhesion of samples were evaluated at elevated temperatures. Also cord/rubber interface was studied by ATR analyze to determine interfacial interactions kind.

Human Asymptomatic Epitope Peptide/CXCL10-Based Prime/Pull Vaccine Induces Herpes Simplex Virus-Specific Gamma Interferon-Positive CD107+ CD8+ T Cells That Infiltrate the Cornea and Trigeminal Ganglia of Humanized HLA Transgenic Rabbits and Protect against Ocular Herpes Challenge.

PubMed

Khan, Arif A; Srivastava, Ruchi; Vahed, Hawa; Roy, Soumyabrata; Walia, Sager S; Kim, Grace J; Fouladi, Mona A; Yamada, Taikun; Ly, Vincent T; Lam, Cynthia; Lou, Anthony; Nguyen, Vivianna; Boldbaatar, Undariya; Geertsema, Roger; Fraser, Nigel W; BenMohamed, Lbachir

2018-06-13

Herpes simplex virus 1 (HSV-1) is a prevalent human pathogen that infects the cornea causing potentially blinding herpetic disease. A clinical herpes vaccine is still lacking. In the present study, a novel prime/pull vaccine was tested in Human Leukocyte Antigen- (HLA-) transgenic rabbit model of ocular herpes (HLA Tg rabbit). Three asymptomatic (ASYMP) peptide epitopes were selected from the HSV-1 membrane glycoprotein C (UL44 400-408 ), the DNA replication binding helicase (UL9 196-204 ), and the tegument protein (UL25 572-580 ), all preferentially recognized by CD8 + T cells from "naturally protected" HSV-1-seropositive healthy ASYMP individuals (who never had recurrent corneal herpetic disease). HLA Tg rabbits were immunized with a mixture of these three ASYMP CD8 + T cell peptide epitopes (UL44 400-408 , UL9 196-204 and UL25 572-580 ), delivered subcutaneously with CpG 2007 adjuvant (prime). Fifteen days later, half of the rabbits received a topical ocular treatment with a recombinant neurotropic AAV8 vector, expressing the T cell-attracting CXCL10 chemokine (pull). The frequency, function of HSV-specific CD8 + T cells induced by the prime/pull vaccine were assessed in peripheral blood, cornea, and trigeminal ganglia (TG). Compared to peptides alone, the peptides/CXCL10 prime/pull vaccine generated frequent polyfunctional gamma interferon-positive (IFN-γ + ) CD107 + CD8 + T cells that infiltrated both the cornea and TG. CD8 + T cells mobilization into cornea and TG of prime/pull- vaccinated rabbits was associated with a significant reduction in corneal herpes infection and disease following an ocular HSV-1 challenge (McKrae). These findings draw attention to the novel prime/pull vaccine strategy to mobilize anti-viral CD8 + T cells into tissues protecting them against herpes infection and disease. IMPORTANCE There is an urgent need for a vaccine against widespread herpes simplex virus infections. The present study demonstrates that immunization of HLA transgenic rabbits with a peptide/CXCL10 prime/pull vaccine triggered mobilization of HSV-specific CD8 + T cells locally in the cornea and TG, the sites of acute and latent herpes infections. Mobilization of antiviral CD8 + T cells into cornea and TG of rabbits that received the prime/pull vaccine was associated with protection against ocular herpes infection and disease following an ocular HSV-1 challenge. These results highlight the importance of the prime/pull vaccine strategy to bolster the number and function of protective CD8 + T cells within infected tissues. Copyright © 2018 American Society for Microbiology.

Results of some initial space qualification testing on triple junction a-Si and CuInSe2 thin film solar cells

NASA Technical Reports Server (NTRS)

Mueller, Robert L.; Anspaugh, Bruce E.

1993-01-01

A series of environmental tests were completed on one type of triple junction a-Si and two types of CuInSe2 thin film solar cells. The environmental tests include electron irradiation at energies of 0.7, 1.0, and 2.0 MeV, proton irradiation at energies of 0.115, 0.24, 0.3, 0.5, 1.0, and 3.0 MeV, post-irradiation annealing at temperatures between 20 C and 60 C, long term exposure to air mass zero (AM0) photons, measurement of the cells as a function of temperature and illumination intensity, and contact pull strength tests. As expected, the cells are very resistant to electron and proton irradiation. However, when a selected cell type is exposed to low energy protons designed to penetrate to the junction region, there is evidence of more significant damage. A significant amount of recovery was observed after annealing in several of the cells. However, it is not permanent and durable, but merely a temporary restoration, later nullified with additional irradiation. Contact pull strengths measured on the triple junction a-Si cells averaged 667 grams, and pull strengths measured on the Boeing CuInSe2 cells averaged 880 grams. Significant degradation of all cell types was observed after exposure to a 580 hour photon degradation test, regardless of whether the cells had been unirradiated or irradiated (electrons or protons). Although one cell from one manufacturer lost approximately 60 percent of its power after the photon test, several other cells from this manufacturer did not degrade at all.

Relationship between isometric and dynamic strength in recreationally trained men.

PubMed

McGuigan, Michael R; Newton, Michael J; Winchester, Jason B; Nelson, Arnold G

2010-09-01

The purpose of this investigation was to examine the relationships between measures of maximal isometric force (peak force [PF]), rate of force development (RFD), vertical jump performance (VJ) and 1-repetition maximum (1RM) strength in recreationally trained men. The subjects in this study were 26 men ([mean +/- SD]: age 22 +/- 1 years; height 175 +/- 7 cm; mass 90 +/- 10 kg). They were tested for PF using the isometric midthigh pull exercise. The 1RM for the squat and bench press exercise were determined as a measure of dynamic strength. Explosive strength was measured as RFD from the isometric force-time curve. Correlations between the variables were calculated using Pearson product moment correlation coefficient. There was a nearly perfect correlation between measures of PF and 1RM squat (r = 0.97, p < 0.05) and 1RM bench press (r = 0.99, p < 0.05). The correlations were very strong between VJ and PF (r = 0.72, p < 0.05) and 1RM bench press (r = 0.70, p < 0.05). There were also strong correlations between VJ and 1RM squat (r = 0.69, p < 0.05). There were no significant correlations with RFD. The results showed that isometric maximum strength determined during the isometric midthigh pull test correlated well with 1RM and VJ testing. However, RFD measured during the same test did not appear to correlate as well with other measures. The isometric midthigh pull provides an efficient method for assessing strength in recreationally trained individuals. Practitioners wishing to obtain performance data related to maximum strength may wish to consider isometric testing as a less time intensive method of testing.

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.

Mobile remote manipulator vehicle system

NASA Technical Reports Server (NTRS)

Bush, Harold G. (Inventor); Mikulas, Martin M., Jr. (Inventor); Wallsom, Richard E. (Inventor); Jensen, J. Kermit (Inventor)

1987-01-01

A mobile remote manipulator system is disclosed for assembly, repair and logistics transport on, around and about a space station square bay truss structure. The vehicle is supported by a square track arrangement supported by guide pins integral with the space station truss structure and located at each truss node. Propulsion is provided by a central push-pull drive mechanism that extends out from the vehicle one full structural bay over the truss and locks drive rods into the guide pins. The draw bar is now retracted and the mobile remote manipulator system is pulled onto the next adjacent structural bay. Thus, translation of the vehicle is inchworm style. The drive bar can be locked onto two guide pins while the extendable draw bar is within the vehicle and then push the vehicle away one bay providing bidirectional push-pull drive. The track switches allow the vehicle to travel in two orthogonal directions over the truss structure which coupled with the bidirectional drive, allow movement in four directions on one plane. The top layer of this trilayered vehicle is a logistics platform. This platform is capable of 369 degees of rotation and will have two astronaut foot restraint platforms and a space crane integral.

Delayed pull-in transitions in overdamped MEMS devices

NASA Astrophysics Data System (ADS)

Gomez, Michael; Moulton, Derek E.; Vella, Dominic

2018-01-01

We consider the dynamics of overdamped MEMS devices undergoing the pull-in instability. Numerous previous experiments and numerical simulations have shown a significant increase in the pull-in time under DC voltages close to the pull-in voltage. Here the transient dynamics slow down as the device passes through a meta-stable or bottleneck phase, but this slowing down is not well understood quantitatively. Using a lumped parallel-plate model, we perform a detailed analysis of the pull-in dynamics in this regime. We show that the bottleneck phenomenon is a type of critical slowing down arising from the pull-in transition. This allows us to show that the pull-in time obeys an inverse square-root scaling law as the transition is approached; moreover we determine an analytical expression for this pull-in time. We then compare our prediction to a wide range of pull-in time data reported in the literature, showing that the observed slowing down is well captured by our scaling law, which appears to be generic for overdamped pull-in under DC loads. This realization provides a useful design rule with which to tune dynamic response in applications, including state-of-the-art accelerometers and pressure sensors that use pull-in time as a sensing mechanism. We also propose a method to estimate the pull-in voltage based only on data of the pull-in times.

An analysis of the pull strength behaviors of fine-pitch, flip chip solder interconnections using a Au-Pt-Pd thick film conductor on Low-Temperature, Co-fired Ceramic (LTCC) substrates.

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

Uribe, Fernando R.; Kilgo, Alice C.; Grazier, John Mark

2008-09-01

The assembly of the BDYE detector requires the attachment of sixteen silicon (Si) processor dice (eight on the top side; eight on the bottom side) onto a low-temperature, co-fired ceramic (LTCC) substrate using 63Sn-37Pb (wt.%, Sn-Pb) in a double-reflow soldering process (nitrogen). There are 132 solder joints per die. The bond pads were gold-platinum-palladium (71Au-26Pt-3Pd, wt.%) thick film layers fired onto the LTCC in a post-process sequence. The pull strength and failure modes provided the quality metrics for the Sn-Pb solder joints. Pull strengths were measured in both the as-fabricated condition and after exposure to thermal cycling (-55/125 C; 15more » min hold times; 20 cycles). Extremely low pull strengths--referred to as the low pull strength phenomenon--were observed intermittently throughout the product build, resulting in added program costs, schedule delays, and a long-term reliability concern for the detector. There was no statistically significant correlation between the low pull strength phenomenon and (1) the LTCC 'sub-floor' lot; (2) grit blasting the LTCC surfaces prior to the post-process steps; (3) the post-process parameters; (4) the conductor pad height (thickness); (5) the dice soldering assembly sequence; or (5) the dice pull test sequence. Formation of an intermetallic compound (IMC)/LTCC interface caused by thick film consumption during either the soldering process or by solid-state IMC formation was not directly responsible for the low-strength phenomenon. Metallographic cross sections of solder joints from dice that exhibited the low pull strength behavior, revealed the presence of a reaction layer resulting from an interaction between Sn from the molten Sn-Pb and the glassy phase at the TKN/LTCC interface. The thick film porosity did not contribute, explicitly, to the occurrence of reaction layer. Rather, the process of printing the very thin conductor pads was too sensitive to minor thixotropic changes to ink, which resulted in inconsistent proportions of metal and glassy phase particles present during the subsequent firing process. The consequences were subtle, intermittent changes to the thick film microstructure that gave rise to the reaction layer and, thus, the low pull strength phenomenon. A mitigation strategy would be the use of physical vapor deposition (PVD) techniques to create thin film bond pads; this is multi-chip module, deposited (MCM-D) technology.« less

Predicting the Drop Performance of Solder Joints by Evaluating the Elastic Strain Energy from High-Speed Ball Pull Tests

NASA Astrophysics Data System (ADS)

You, Taehoon; Kim, Yunsung; Kim, Jina; Lee, Jaehong; Jung, Byungwook; Moon, Jungtak; Choe, Heeman

2009-03-01

Despite being expensive and time consuming, board-level drop testing has been widely used to assess the drop or impact resistance of the solder joints in handheld microelectronic devices, such as cellphones and personal digital assistants (PDAs). In this study, a new test method, which is much simpler and quicker, is proposed. The method involves evaluating the elastic strain energy and relating it to the impact resistance of the solder joint by considering the Young’s modulus of the bulk solder and the fracture stress of the solder joint during a ball pull test at high strain rates. The results show that solder joints can be ranked in order of descending elastic strain energy as follows: Sn-37Pb, Sn-1Ag-0.5Cu, Sn-3Ag-0.5Cu, and Sn-4Ag-0.5Cu. This order is consistent with the actual drop performances of the samples.

Psychophysical basis for maximum pushing and pulling forces: A review and recommendations.

PubMed

Garg, Arun; Waters, Thomas; Kapellusch, Jay; Karwowski, Waldemar

2014-03-01

The objective of this paper was to perform a comprehensive review of psychophysically determined maximum acceptable pushing and pulling forces. Factors affecting pushing and pulling forces are identified and discussed. Recent studies show a significant decrease (compared to previous studies) in maximum acceptable forces for males but not for females when pushing and pulling on a treadmill. A comparison of pushing and pulling forces measured using a high inertia cart with those measured on a treadmill shows that the pushing and pulling forces using high inertia cart are higher for males but are about the same for females. It is concluded that the recommendations of Snook and Ciriello (1991) for pushing and pulling forces are still valid and provide reasonable recommendations for ergonomics practitioners. Regression equations as a function of handle height, frequency of exertion and pushing/pulling distance are provided to estimate maximum initial and sustained forces for pushing and pulling acceptable to 75% male and female workers. At present it is not clear whether pushing or pulling should be favored. Similarly, it is not clear what handle heights would be optimal for pushing and pulling. Epidemiological studies are needed to determine relationships between psychophysically determined maximum acceptable pushing and pulling forces and risk of musculoskeletal injuries, in particular to low back and shoulders.

Psychophysical basis for maximum pushing and pulling forces: A review and recommendations

PubMed Central

Garg, Arun; Waters, Thomas; Kapellusch, Jay; Karwowski, Waldemar

2015-01-01

The objective of this paper was to perform a comprehensive review of psychophysically determined maximum acceptable pushing and pulling forces. Factors affecting pushing and pulling forces are identified and discussed. Recent studies show a significant decrease (compared to previous studies) in maximum acceptable forces for males but not for females when pushing and pulling on a treadmill. A comparison of pushing and pulling forces measured using a high inertia cart with those measured on a treadmill shows that the pushing and pulling forces using high inertia cart are higher for males but are about the same for females. It is concluded that the recommendations of Snook and Ciriello (1991) for pushing and pulling forces are still valid and provide reasonable recommendations for ergonomics practitioners. Regression equations as a function of handle height, frequency of exertion and pushing/pulling distance are provided to estimate maximum initial and sustained forces for pushing and pulling acceptable to 75% male and female workers. At present it is not clear whether pushing or pulling should be favored. Similarly, it is not clear what handle heights would be optimal for pushing and pulling. Epidemiological studies are needed to determine relationships between psychophysically determined maximum acceptable pushing and pulling forces and risk of musculoskeletal injuries, in particular to low back and shoulders. PMID:26664045

Cyclic biomechanical testing of biocomposite lateral row knotless anchors in a human cadaveric model.

PubMed

Barber, F Alan; Bava, Eric D; Spenciner, David B; Piccirillo, Justin

2013-06-01

The purpose of this study was to assess the mechanical performance of biocomposite knotless lateral row anchors based on both anchor design and the direction of pull. Two lateral row greater tuberosity insertion sites (anterior and posterior) were identified in matched pairs of fresh-frozen human cadaveric shoulders DEXA (dual energy X-ray absorptiometry) scanned to verify comparability. The humeri were stripped of all soft tissue and 3 different biocomposite knotless lateral row anchors: HEALIX Knotless BR (DePuy Mitek, Raynham MA), BioComposite PushLock (Arthrex, Naples, FL), and Bio-SwiveLock (Arthrex). Fifty-two anchors were distributed among the insertion locations and tested them with either an anatomic or axial pull. A fixed-gauge loop (15 mm) of 2 high-strength sutures from each anchor was created. After a 10-Nm preload, anchors were cycled from 10 to 45 Nm at 0.5 Hz for 200 cycles and tested to failure at 4.23 mm/second. The load to reach 3 mm and 5 mm displacement, ultimate failure load, displacement at ultimate failure, and failure mode were recorded. Threaded anchors (Bio-SwiveLock, P = .03; HEALIX Knotless, P = .014) showed less displacement with anatomic testing than did the nonthreaded anchor (BioComposite PushLock), and the HEALIX Knotless showed less overall displacement than did the other 2 anchors. The Bio-SwiveLock exhibited greater failure loads than did the other 2 anchors (P < .05). Comparison of axial and anatomic loading showed no maximum load differences for all anchors as a whole (P = .1084). Yet, anatomic pulling produced higher failure loads than did axial pulling for the Bio-SwiveLock but not for the BioComposite PushLock or the HEALIX Knotless. The nonthreaded anchor (BioComposite PushLock) displayed lower failure loads than did both threaded anchors with axial pulling. Threaded biocomposite anchors (HEALIX Knotless BR and Bio-SwiveLock) show less anatomic loading displacement and higher axial failure loads than do the nonthreaded (BioComposite PushLock) anchor. The HEALIX Knotless BR anchor showed less displacement than did the BioComposite PushLock and Bio-SwiveLock anchors. Neither axial nor anatomic loading had an effect on overall anchor displacement. Because of the strength profiles exhibited, this study supports the use of biocomposite anchors, which have definite advantages over polyetheretherketone (PEEK) and metal products. However, the nonthreaded BioComposite PushLock anchor cannot be recommended. Copyright © 2013 Arthroscopy Association of North America. All rights reserved.

Reinforcement of osteosynthesis screws with brushite cement.

PubMed

Van Landuyt, P; Peter, B; Beluze, L; Lemaître, J

1999-08-01

The fixation of osteosynthesis screws remains a severe problem for fracture repair among osteoporotic patients. Polymethyl-methacrylate (PMMA) is routinely used to improve screw fixation, but this material has well-known drawbacks such as monomer toxicity, exothermic polymerization, and nonresorbability. Calcium phosphate cements have been developed for several years. Among these new bone substitution materials, brushite cements have the advantage of being injectable and resorbable. The aim of this study is to assess the reinforcement of osteosynthesis screws with brushite cement. Polyurethane foams, whose density is close to that of cancellous bone, were used as bone model. A hole was tapped in a foam sample, then brushite cement was injected. Trabecular osteosynthesis screws were inserted. After 24 h of aging in water, the stripping force was measured by a pull-out test. Screws (4.0 and 6.5 mm diameter) and two foam densities (0.14 and 0.28 g/cm3) were compared. Cements with varying solid/liquid ratios and xanthan contents were used in order to obtain the best screw reinforcement. During the pull-out test, the stripping force first increases to a maximum, then drops to a steady-state value until complete screw extraction. Both maximum force and plateau value increase drastically in the presence of cement. The highest stripping force is observed for 6.5-mm screws reinforced with cement in low-density foams. In this case, the stripping force is multiplied by 3.3 in the presence of cement. In a second experiment, cements with solid/liquid ratio ranging from 2.0 to 3.5 g/mL were used with 6.5-mm diameter screws. In some compositions, xanthan was added to improve injectability. The best results were obtained with 2.5 g/mL cement containing xanthan and with 3.0 g/mL cements without xanthan. A 0.9-kN maximal stripping force was observed with nonreinforced screws, while 1.9 kN was reached with reinforced screws. These first results are very promising regarding screw reinforcement with brushite cement. However, the polyurethane foam model presents noninterconnected porosity and physiological liquid was not modelized.

Reaching out towards cannabis: approach-bias in heavy cannabis users predicts changes in cannabis use

PubMed Central

Cousijn, Janna; Goudriaan, Anna E; Wiers, Reinout W

2011-01-01

Aims Repeated drug exposure can lead to an approach-bias, i.e. the relatively automatically triggered tendencies to approach rather that avoid drug-related stimuli. Our main aim was to study this approach-bias in heavy cannabis users with the newly developed cannabis Approach Avoidance Task (cannabis-AAT) and to investigate the predictive relationship between an approach-bias for cannabis-related materials and levels of cannabis use, craving, and the course of cannabis use. Design, settings and participants Cross-sectional assessment and six-month follow-up in 32 heavy cannabis users and 39 non-using controls. Measurements Approach and avoidance action-tendencies towards cannabis and neutral images were assessed with the cannabis AAT. During the AAT, participants pulled or pushed a joystick in response to image orientation. To generate additional sense of approach or avoidance, pulling the joystick increased picture size while pushing decreased it. Craving was measured pre- and post-test with the multi-factorial Marijuana Craving Questionnaire (MCQ). Cannabis use frequencies and levels of dependence were measured at baseline and after a six-month follow-up. Findings Heavy cannabis users demonstrated an approach-bias for cannabis images, as compared to controls. The approach-bias predicted changes in cannabis use at six-month follow-up. The pre-test MCQ emotionality and expectancy factor were associated negatively with the approach-bias. No effects were found on levels of cannabis dependence. Conclusions Heavy cannabis users with a strong approach-bias for cannabis are more likely to increase their cannabis use. This approach-bias could be used as a predictor of the course of cannabis use to identify individuals at risk from increasing cannabis use. PMID:21518067

Anomalous transport in fracture networks: field scale experiments and modelling

NASA Astrophysics Data System (ADS)

Kang, P. K.; Le Borgne, T.; Bour, O.; Dentz, M.; Juanes, R.

2012-12-01

Anomalous transport is widely observed in different settings and scales of transport through porous and fractured geologic media. A common signature of anomalous transport is the late-time power law tailing in breakthrough curves (BTCs) during tracer tests. Various conceptual models of anomalous transport have been proposed, including multirate mass transfer, continuous time random walk, and stream tube models. Since different conceptual models can produce equally good fits to a single BTC, tracer test interpretation has been plagued with ambiguity. Here, we propose to resolve such ambiguity by analyzing BTCs obtained from both convergent and push-pull flow configurations at two different fracture planes. We conducted field tracer tests in a fractured granite formation close to Ploemeur, France. We observe that BTC tailing depends on the flow configuration and the injection fracture. Specifically the tailing disappears under push-pull geometry, and when we injected at a fracture with high flux (Figure 1). This indicates that for this fractured granite, BTC tailing is controlled by heterogeneous advection and not by matrix diffusion. To explain the change in tailing behavior for different flow configurations, we employ a simple lattice network model with heterogeneous conductivity distribution. The model assigns random conductivities to the fractures and solves the Darcy equation for an incompressible fluid, enforcing mass conservation at fracture intersections. The mass conservation constraint yields a correlated random flow through the fracture system. We investigate whether BTC tailing can be explained by the spatial distribution of preferential flow paths and stagnation zones, which is controlled by the conductivity variance and correlation length. By combining the results from the field tests and numerical modeling, we show that the reversibility of spreading is a key mechanism that needs to be captured. We also demonstrate the dominant role of the injection fracture on the tailing behavior: where we inject makes the difference in the tailing. Blue line is a BTC with injection into a slow velocity zone under convergent flow configuration. The late-time tailing observed for the convergent test diminished for push-pull experiment performed in the same zone(red line). Black line is a BTC with injection into a high velocity zone under convergent flow configuration. Insets: illustration of convergent and push-pull tracer tests using a double packer system.

Are We Pulling the Rug out from under Their Feet? What if Academic Interventions Are Removed?

ERIC Educational Resources Information Center

Lively Summers, Robin M.

2014-01-01

With the loss of revenue and education cut backs, school districts have faced the loss of supplemental academic supports such as after school tutoring and summer school programs. Up until recently research has focused on improving student outcomes by implementing supplemental instruction. There was little research available that examined the…

Enhancing Unity of Effort in Homeland Defense, Homeland Security, and Civil Support Through Interdisciplinary Education

DTIC Science & Technology

2010-03-01

to put greatness into these guys, I was trying to pull it out.” The U.S. hockey team learned to work together and demonstrated, in Brooks’ words...skating, passing, defending, and shooting. The goalie works to protect the net from intruding pucks, releasing the puck to his teammates, and defense

An Evaluation of Counterinsurgency as a Strategy for Fighting the Long War

DTIC Science & Technology

2011-03-01

controlled through support to an insurgency. If a terrorist bomb is analo- gized to an exploding soccer ball, antiterrorism is the goalie who prevents...the weapon. 91. “US Pulls Out of Saudi Arabia,” BBC News, April 29, 2003, available from news.bbc.co.uk/2/hi/ middle_east/ 2984547.stm. 92. A belief

Compendium of Operations Research and Economic Analysis Studies

DTIC Science & Technology

1990-10-01

Constraining buslo a mxiu f1 ot will real-ize a- near tverm’, reduction of approximiateIy .$25- mil-lion. Achieving co it er goalI rvducrtions for short er Yead...which have no potential to achieve consolidation cost effectiveness and pull these out of the bank early for shipment, and (4) that the depots allow

An Evaluation of Counterinsurgency as a Strategy for Fighting the Long War

DTIC Science & Technology

2010-05-20

an exploding soccer ball, antiterrorism is the goalie who prevents the proximate bomb from entering the U.S., or who covers the ball that has...it would require the use heavy equipment for multiple days to remove the weapon. 91 “US Pulls Out of Saudi Arabia,” BBC News, 29 April 2003

The Prerequisites to Ukrainian Students Participation in Study Abroad Programs at the Canadian Universities and Colleges

ERIC Educational Resources Information Center

Zhukovskyi, Vasyl; Simak, Kateryna

2015-01-01

The problem of outbound mobility of Ukrainian students has been presented in the paper. The data regarding the number of Ukrainian students studying in Canada has been pointed out. This paper examines "push-pull" factors which motivate Ukrainian students to seek higher education overseas and factors which attract Ukrainian students to…

30 CFR 250.1623 - Well-control fluids, equipment, and operations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... measuring device for determining fluid volumes when filling the hole on trips, and (3) A recording mud-pit... and an audible warning device. (c) When coming out of the hole with drill pipe or a workover string... that may be pulled prior to filling the hole and the equivalent well-control fluid volume shall be...

30 CFR 250.514 - Well-control fluids, equipment, and operations.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-control, fluid-volume measuring device for determining fluid volumes when filling the hole on trips; and... shall include both a visual and an audible warning device. (c) When coming out of the hole with drill... collars that may be pulled prior to filling the hole and the equivalent well-control fluid volume shall be...

30 CFR 250.1623 - Well-control fluids, equipment, and operations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... measuring device for determining fluid volumes when filling the hole on trips, and (3) A recording mud-pit... and an audible warning device. (c) When coming out of the hole with drill pipe or a workover string... that may be pulled prior to filling the hole and the equivalent well-control fluid volume shall be...

30 CFR 250.1623 - Well-control fluids, equipment, and operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... measuring device for determining fluid volumes when filling the hole on trips, and (3) A recording mud-pit... and an audible warning device. (c) When coming out of the hole with drill pipe or a workover string... that may be pulled prior to filling the hole and the equivalent well-control fluid volume shall be...

30 CFR 250.614 - Well-control fluids, equipment, and operations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... well is shut in and secured. (b) When coming out of the hole with drill pipe or a workover string, the... string and drill collars that may be pulled prior to filling the hole and the equivalent well-control... fluid volumes when filling the hole on trips; and (3) A recording mud-pit-level indicator to determine...

Wielding the Military Shield and the Civilian Sword: Norwegian Civil-Military Interagency Cooperation in Afghanistan

DTIC Science & Technology

2010-06-11

and Mads A. Andersen, “SV: Vi boer sette dato for uttrekning fra Afghanistan” [SV: We should set a date for pulling out of Afghanistan], Verdens Gang......Norwegian context, the research had to be based on other sources. The obvious solution to the problem was to interview professionals with practical

Evaluation of the Effects of Programming Arrangements on Student Learning Outcomes. Research Monograph 94108.

ERIC Educational Resources Information Center

Delcourt, Marcia A. B.; And Others

The Learning Outcomes Study, a 2-year investigation, evaluated four popular types of grouping arrangements for gifted students in grades 2 and 3 in 14 collaborative school districts in 10 states. The study compared within-class, pull-out, separate class, and special school instructional arrangements. Study participants (N=1000) included students…

Jump as Far as You Can [Problem Solvers: Solutions

ERIC Educational Resources Information Center

Yigit, Melike; Bofferding, Laura; Warnock, Miranda

2014-01-01

The How Far Do You Think You Can Jump? activity (see EJ1174770) was completed in three different contexts: an after-school mathematics enrichment program at Woodland and Country Schools in Weston, Massachusetts; a small-group pull-out of second graders at Wren Elementary in Piedmont, South Carolina; and a family math night in Lafayette, Indiana.…

The Effect of Grouping and Program Type on Scholastic and Affective Outcomes in the Mawhiba Schools Partnership Initiative

ERIC Educational Resources Information Center

Batterjee, Adel A.

2016-01-01

Researchers have struggled for decades to determine whether ability grouping is helpful or harmful; however, study findings have been inconsistent. To assess the effect of grouping and program type on scholastic and affective outcomes, three grouping types (gifted separate-class enrichment, pull-out gifted enrichment, and no enrichment), three…

Pulling Words Out of a Hat: Magic in ESL Lessons.

ERIC Educational Resources Information Center

Friedenberg, Randi D.

Magic motivates students to talk, and stimulates the affective domain. While watching magic, many people imagine how the effect is accomplished or how they might perform the trick if they were performing. This can be extended into an English lesson by using phrases such as, "If I were a magician, I could..." Total physical response…

Latino Child Poverty in the United States.

ERIC Educational Resources Information Center

Miranda, Leticia C.

Poverty among Latino children has soared during the past decade, accounting for half of the total growth in the number of American children who are poor. One in three Latino children was living in poverty as of 1989. Many Latino children are poor despite their parents' best efforts to pull their families out of poverty and despite the fact that…

Negotiating Grammatical Choices: Academic Language Learning by Secondary ESL Students

ERIC Educational Resources Information Center

Shin, Sarah J.

2009-01-01

This paper reports on a part of a year-long investigation into high school ESL students' academic language development. Eight participants were pulled out of their intermediate ESL class for weekly 50-minute sessions with the author for a year. While the main focus of the sessions was reading news magazine articles for meaning, the author…

Pulling My Gut out--Simple Tools for Engaging Students in Gross Anatomy Lectures

ERIC Educational Resources Information Center

Chan, Lap Ki

2010-01-01

A lecture is not necessarily a monologue, promoting only passive learning. If appropriate techniques are used, a lecture can stimulate active learning too. One such method is demonstration, which can engage learners' attention and increase the interaction between the lecturer and the learners. This article describes two simple and useful tools for…

It's Not about Grit: Trauma, Inequity, and the Power of Transformative Teaching

ERIC Educational Resources Information Center

Goodman, Steven

2018-01-01

Speaking out against decades of injustice and challenging deficit perceptions of young learners and their families, "It's Not About Grit" pulls back the veil, revealing the social systems that marginalize and stigmatize mostly poor, urban students of color and their communities. At the same time, author Steven Goodman, founding executive…

Witnessing the World: The Power of True Global Service

ERIC Educational Resources Information Center

Piccone, Chris

2013-01-01

The school where Chris Piccone teaches eighth-grade English maintains a desire to pull its community from its comfort zones to experience first hand the crushing poverty in the Dominican Republic. Although he always thought of himself as a bleeding heart, who was proud that he pushed his students out of their academic comfort zones, he realized…

Supporting Teachers' Use of Research-Based Instructional Sequences

ERIC Educational Resources Information Center

Cobb, Paul; Jackson, Kara

2015-01-01

In this paper, we frame the dissemination of the products of classroom design studies as a process of supporting the learning of large numbers of teachers. We argue that high-quality pull-out professional development is essential but not sufficient, and go on to consider teacher collaboration and one-on-one coaching in the classroom as additional…

Symbols and Scrolls: Teaching Elementary Students about Historic Writing. Pull-out 2.

ERIC Educational Resources Information Center

Christensen, Lois M.

1999-01-01

Describes a unit for elementary students on the history and technology of writing from ancient to medieval times. Includes a contemporary writing and print exercise, an ancient and medieval writing exercise, a research activity on the evolution of writing, a biography study, a fine arts exercise, and a community survey. Addresses the unit…

Take the "C" Train

ERIC Educational Resources Information Center

Lawton, Rebecca

2008-01-01

In this essay, the author recalls several of her experiences in which she successfully pulled her boats out of river holes by throwing herself to the water as a sea-anchor. She learned this trick from her senior guides at a spring training. Her guides told her, "When you're stuck in a hole, take the "C" train."" "Meaning?" The author asked her…

Calcium phosphate compatible bone cement: Characterization, bonding properties and tissue response

NASA Astrophysics Data System (ADS)

Roemhildt, Maria Lynn

A novel, inorganic, bone cement, containing calcium phosphate, developed for implant fixation was evaluated. Setting properties were determined over a range of temperatures. The flow of the cement was greatly increased by application of vibration. Changes in the cement during hydration and aging were evaluated. Compressive strength of the cement over time was studied under simulated physiological conditions from 1 hour to 1 year after setting. After 1 day, this cement had equivalent compressive strength to commercially used PMMA cement. The strength was found to increase over 1 month and high strength was maintained up to 1 year. The shear strength of the cement-metal interface was studied in vitro using a pull-out test. Prepared specimens were stored under physiological conditions and tested at 4 hours, 24 hours, and 60 days. Comparable interfacial shear strength values were found at 4 hours, 24 hours and 60 days for the experimental cement and were not significantly different from values obtained for PMMA cement. In vivo tissue response was evaluated after cement implantation in the femoral medullary canal in canines. Tissue response and bonding at the cement-bone interface were evaluated at 2, 6, and 12 weeks. Cortical bone was found in direct contact with the OC-cement and was healthy. The strength of the cement-bone interface, measured using a push-out test, was significantly higher for the experimental cement than for commercial PMMA bone cement.

Effect of Waterproofing Admixtures on the Flexural Strength and Corrosion Resistance of Concrete

NASA Astrophysics Data System (ADS)

Geetha, A.; Perumal, P.

2012-02-01

This paper deals about the flexural strength and corrosion behaviour of concrete using waterproofing admixtures. The effect of waterproofing admixtures on the corrosion behaviour of RCC specimen has been studied by conducting accelerated corrosion test. To identify the effect of corrosion in pull out strength, corrosion process was induced by means of accelerated corrosion procedure. To accelerate the reinforcement corrosion, direct electric current was impressed on the rebar embedded in the specimen using a DC power supply system that has a facility to adjust voltage. The addition of waterproofing admixtures also shows the improvement in the flexural strength of concrete has been studied by conducting flexural strength tests on the concrete prism specimen of size 100 × 100 × 500 mm with and without admixtures for various dosages and various curing periods of 7 and 28 days. The results showed that the presence of waterproofing admixtures always improves the corrosion resistance and thus increases the strength of concrete due to the hydrophobic action of waterproofing admixtures.

KSC-2013-3067

NASA Image and Video Library

2013-07-08

LAS VEGAS, Nev. – The Boeing Company performed simulated contingency water landing scenarios with a mock-up CST-100 spacecraft at Bigelow Aerospace's headquarters near Las Vegas. The CST-100 is designed for ground landings, but could splash down on the water, if necessary. During the water tests, Department of Defense search-and-recovery personnel practiced pulling five Boeing engineers out of the capsule and to safety. The tests are part of the company’s ongoing work supporting its funded Space Act Agreement with NASA’s Commercial Crew Program, or CCP, during the Commercial Crew Integrated Capability, or CCiCap, initiative. CCP is intended to lead to the availability of commercial human spaceflight services for government and commercial customers to low-Earth orbit. Future development and certification initiatives eventually will lead to the availability of human spaceflight services for NASA to send its astronauts to the International Space Station, where critical research is taking place daily. For more information about CCP, go to http://www.nasa.gov/commercialcrew. Photo credit: Boeing

Self-cutting blades and their influence on primary stability of tapered dental implants in a simulated low-density bone model: a laboratory study.

PubMed

Kim, Duck-Rae; Lim, Young-Jun; Kim, Myung-Joo; Kwon, Ho-Beom; Kim, Sung-Hun

2011-11-01

This study tested the hypothesis that there would be differences in primary stability due to the presence of self cutting blades. We investigated the effect of a self-cutting blade implant design on the primary stability of tapered dental implants in a simulated low-density bone model. Implant fixtures with 2 different designs, one with self-cutting blades and the other without self-cutting blades, were fabricated in the same implant system. Insertion torque, resonance frequency analysis, reverse torque, and pull-out and push-in tests were evaluated in grade no. 10 solid rigid polyurethane foam. All 5 assessments of the group without self-cutting blades were significantly higher than those of the self-cutting group (P < .001). The implants without self-cutting blades create a lateral compression with increased contact surface area and consequently improve the primary stability in a simulated low-density bone model. Copyright © 2011 Mosby, Inc. All rights reserved.

Tensile experiments and SEM fractography on bovine subchondral bone.

PubMed

Braidotti, P; Bemporad, E; D'Alessio, T; Sciuto, S A; Stagni, L

2000-09-01

Subchondral bone undecalcified samples, extracted from bovine femoral heads, are subjected to a direct tensile load. The Young's modulus of each sample is determined from repeated tests within the elastic limit. In a last test, the tensile load is increased up to the specimen failure, determining the ultimate tensile strength. The investigation is performed on both dry and wet specimens. The measured Young's modulus for dry samples is 10.3+/-2.5GPa, while that of wet samples is 3.5+/-1.2GPa. The ultimate tensile strengths are 36+/-10 and 30+/-7.5MPa for dry and wet specimens, respectively. SEM micrographs of failure surfaces show characteristic lamellar bone structures, with lamellae composed of calcified collagen fibers. Rudimentary osteon-like structures are also observed. Failure surfaces of wet samples show a marked fiber pull-out, while delamination predominates in dry samples. The obtained results are interpreted on the basis of the deformation mechanisms typical of fiber-reinforced laminated composite materials.

Shear test on viscoelastic granular material using Contact Dynamics simulations

NASA Astrophysics Data System (ADS)

Quezada, Juan Carlos; Sagnol, Loba; Chazallon, Cyrille

2017-06-01

By means of 3D contact dynamic simulations, the behavior of a viscoelastic granular material under shear loading is investigated. A viscoelastic fluid phase surrounding the solid particles is simulated by a contact model acting between them. This contact law was implemented in the LMGC90 software, based on the Burgers model. This model is able to simulate also the effect of creep relaxation. To validate the proposed contact model, several direct shear tests were performed, experimentally and numerically using the Leutner device. The numerical samples were created using spheres with two particle size distribution, each one identified for two layers from a road structure. Our results show a reasonable agreement between experimental and numerical data regarding the strain-stress evolution curves and the stress levels measured at failure. The proposed model can be used to simulate the mechanical behavior of multi-layer road structure and to study the influence of traffic on road deformation, cracking and particles pull-out induced by traffic loading.

Mechanisms of renewal after the extinction of instrumental behavior

PubMed Central

Todd, Travis P.

2013-01-01

Four experiments with rats examined renewal of extinguished instrumental behavior when the reinforcement histories of the contexts were equated by giving complementary training and extinction of a different response (lever press and chain pull) in each context. In Experiments 1–3, renewal occurred when the response was tested in the acquisition context (ABA) or outside the extinction context (AAB and ABC). Further, in Experiments 1–3, when both responses were simultaneously available there was a clear preference for the response that was not in its extinction context. In Experiment 4, renewal was not reduced when testing occurred in a context that had been associated with extinction of the other instrumental response. The experimental designs rule out differential context-reinforcer associations being the only contributing mechanism of renewal, and also raise questions about configural and occasion-setting accounts. The results are consistent with the idea that during extinction an inhibitory association is formed between the context and the response. PMID:23627796

Conditions for sustainability of Academic Collaborative Centres for Public Health in the Netherlands: a mixed methods design.

PubMed

Jansen, Maria W J; van Oers, Hans A M; Middelweerd, Mizzi D R; van de Goor, Ien A M; Ruwaard, Dirk

2015-08-21

Contemporary research should increasingly be carried out in the context of application. Nowotny called this new form of knowledge production Mode-2. In line with Mode-2 knowledge production, the Dutch government in 2006 initiated the so-called Academic Collaborative Centres (ACC) for Public Health. The aim of these ACCs is to build a regional, sustainable knowledge-sharing network to deliver socially robust knowledge. The present study aims to highlight the enabling and constraining push and pull factors of these ACCs in order to assess whether the ACCs are able to build and strengthen a sustainable integrated organizational network between public health policy, practice, and research. Our empirical analysis builds on a mixed methods design. Quantitative data was derived from records of a survey sent to all 11 ACCs about personnel investments, number and nature of projects, and earning power. Qualitative data was derived from 21 in-depth interviews with stakeholders involved. The interviews were tape-recorded, transcribed, and manually coded as favourable or unfavourable pull or push factors. The extra funding appeared to be the most enabling push factor. The networks secured external grants for about 150 short- and long-term Mode-2 knowledge production projects in the past years. Enabling pull factors improved, especially the number of policy-driven short-term research projects. Exchange agents were able to constructively deal with the constraining push factors, like university's publication pressure and budget limitations. However, the constraining pull factors like local government's involvement and their low demand for scientific evidence were difficult to overcome. A clear improvement of the organizational networks was noticed whereby the ACC's were pushed rather than pulled. Efforts are needed to increase the demand for scientific and socially robust evidence from policymakers and to resolve the regime differences between the research and policy systems, in order to make the bidirectionality of the links sustainable.

High temperature aqueous stress corrosion testing device

DOEpatents

Bornstein, A.N.; Indig, M.E.

1975-12-01

A description is given of a device for stressing tensile samples contained within a high temperature, high pressure aqueous environment, thereby permitting determination of stress corrosion susceptibility of materials in a simple way. The stressing device couples an external piston to an internal tensile sample via a pull rod, with stresses being applied to the sample by pressurizing the piston. The device contains a fitting/seal arrangement including Teflon and weld seals which allow sealing of the internal system pressure and the external piston pressure. The fitting/seal arrangement allows free movement of the pull rod and the piston.

Discrete Element Method Simulation of a Boulder Extraction From an Asteroid

NASA Technical Reports Server (NTRS)

Kulchitsky, Anton K.; Johnson, Jerome B.; Reeves, David M.; Wilkinson, Allen

2014-01-01

The force required to pull 7t and 40t polyhedral boulders from the surface of an asteroid is simulated using the discrete element method considering the effects of microgravity, regolith cohesion and boulder acceleration. The connection between particle surface energy and regolith cohesion is estimated by simulating a cohesion sample tearing test. An optimal constant acceleration is found where the peak net force from inertia and cohesion is a minimum. Peak pulling forces can be further reduced by using linear and quadratic acceleration functions with up to a 40% reduction in force for quadratic acceleration.

An experimental study of non-destructive testing on glass fibre reinforced polymer composites after high velocity impact event

NASA Astrophysics Data System (ADS)

Razali, N.; Sultan, M. T. H.; Cardona, F.

2016-10-01

A non-destructive testing method on Glass Fibre Reinforced Polymer (GFRP) after high velocity impact event using single stage gas gun (SSGG) is presented. Specimens of C- type and E-type fibreglass reinforcement, which were fabricated with 6mm, 8mm, 10mm and 12mm thicknesses and size 100 mm x 100 mm, were subjected to a high velocity impact with three types of bullets: conical, hemispherical and blunt at various gas gun pressure levels from 6 bar to 60 bar. Visual observation techniques using a lab microscope were used to determine the infringed damage by looking at the crack zone. Dye penetrants were used to inspect the area of damage, and to evaluate internal and external damages on the specimens after impact. The results from visual analysis of the impacted test laminates were discussed and presented. It was found that the impact damage started with induced delamination, fibre cracking and then failure, simultaneously with matrix cracking and breakage, and finally followed by the fibres pulled out. C-type experienced more damaged areas compared to E-type of GFRP.

KSC-2014-3665

NASA Image and Video Library

2014-08-25

CAPE CANAVERAL, Fla. – The umbilical swing arm for Orion's Exploration Flight Test 1, or EFT-1, has been attached to the uppermost location on the fixed umbilical tower at Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida. All three swing arms on the tower are undergoing tests to confirm that they are operating correctly. They are being swung out and closer to the Vertical Integration Facility at the pad. The uppermost swing arm will carry umbilicals that will be mated to Orion's launch abort system and environmental control system. During launch, all three umbilicals will pull away from Orion and the United Launch Alliance Delta IV Heavy rocket at T-0. During the EFT-1 mission, Orion will travel farther into space than any human spacecraft has gone in more than 40 years. The data gathered during the flight will influence design decisions, validate existing computer models and innovative new approaches to space systems development, as well as reduce overall mission risks and costs for later Orion flights. Liftoff of Orion on its first flight test is planned for fall 2014. Photo credit: NASA/Daniel Casper

KSC-2014-3664

NASA Image and Video Library

2014-08-25

CAPE CANAVERAL, Fla. – The umbilical swing arm for Orion's Exploration Flight Test 1, or EFT-1, has been attached to the uppermost location on the fixed umbilical tower at Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida. All three swing arms on the tower are undergoing tests to confirm that they are operating correctly. They are being swung out and closer to the Vertical Integration Facility at the pad. The uppermost swing arm will carry umbilicals that will be mated to Orion's launch abort system and environmental control system. During launch, all three umbilicals will pull away from Orion and the United Launch Alliance Delta IV Heavy rocket at T-0. During the EFT-1 mission, Orion will travel farther into space than any human spacecraft has gone in more than 40 years. The data gathered during the flight will influence design decisions, validate existing computer models and innovative new approaches to space systems development, as well as reduce overall mission risks and costs for later Orion flights. Liftoff of Orion on its first flight test is planned for fall 2014. Photo credit: NASA/Daniel Casper

KSC-2014-3667

NASA Image and Video Library

2014-08-25

CAPE CANAVERAL, Fla. – The umbilical swing arm for Orion's Exploration Flight Test 1, or EFT-1, has been attached to the uppermost location on the fixed umbilical tower at Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida. All three swing arms on the tower are undergoing tests to confirm that they are operating correctly. They are being swung out and closer to the Vertical Integration Facility at the pad. The uppermost swing arm will carry umbilicals that will be mated to Orion's launch abort system and environmental control system. During launch, all three umbilicals will pull away from Orion and the United Launch Alliance Delta IV Heavy rocket at T-0. During the EFT-1 mission, Orion will travel farther into space than any human spacecraft has gone in more than 40 years. The data gathered during the flight will influence design decisions, validate existing computer models and innovative new approaches to space systems development, as well as reduce overall mission risks and costs for later Orion flights. Liftoff of Orion on its first flight test is planned for fall 2014. Photo credit: NASA/Daniel Casper

KSC-2014-3663

NASA Image and Video Library

2014-08-25

CAPE CANAVERAL, Fla. – The umbilical swing arm for Orion's Exploration Flight Test 1, or EFT-1, has been attached to the uppermost location on the fixed umbilical tower at Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida. All three swing arms on the tower are undergoing tests to confirm that they are operating correctly. They are being swung out and closer to the Vertical Integration Facility at the pad. The uppermost swing arm will carry umbilicals that will be mated to Orion's launch abort system and environmental control system. During launch, all three umbilicals will pull away from Orion and the United Launch Alliance Delta IV Heavy rocket at T-0. During the EFT-1 mission, Orion will travel farther into space than any human spacecraft has gone in more than 40 years. The data gathered during the flight will influence design decisions, validate existing computer models and innovative new approaches to space systems development, as well as reduce overall mission risks and costs for later Orion flights. Liftoff of Orion on its first flight test is planned for fall 2014. Photo credit: NASA/Daniel Casper

KSC-2014-3666

NASA Image and Video Library

2014-08-25

CAPE CANAVERAL, Fla. – The umbilical swing arm for Orion's Exploration Flight Test 1, or EFT-1, has been attached to the uppermost location on the fixed umbilical tower at Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida. All three swing arms on the tower are undergoing tests to confirm that they are operating correctly. They are being swung out and closer to the Vertical Integration Facility at the pad. The uppermost swing arm will carry umbilicals that will be mated to Orion's launch abort system and environmental control system. During launch, all three umbilicals will pull away from Orion and the United Launch Alliance Delta IV Heavy rocket at T-0. During the EFT-1 mission, Orion will travel farther into space than any human spacecraft has gone in more than 40 years. The data gathered during the flight will influence design decisions, validate existing computer models and innovative new approaches to space systems development, as well as reduce overall mission risks and costs for later Orion flights. Liftoff of Orion on its first flight test is planned for fall 2014. Photo credit: NASA/Daniel Casper

Effect of Nd:YAG laser beam welding on weld morphology and mechanical properties of Ti-6Al-4V butt joints and T-joints

NASA Astrophysics Data System (ADS)

Kashaev, Nikolai; Ventzke, Volker; Fomichev, Vadim; Fomin, Fedor; Riekehr, Stefan

2016-11-01

A Nd:YAG single-sided laser beam welding process study for Ti-6Al-4V butt joints and T-joints was performed to investigate joining techniques with regard to the process-weld morphology relationship. An alloy compatible filler wire was used to avoid underfills and undercuts. The quality of the butt joints and T-joints was characterized in terms of weld morphology, microstructure and mechanical properties. Joints with regular shapes, without visible cracks, pores, and geometrical defects were achieved. Tensile tests revealed high joint integrity in terms of strength and ductility for both the butt joint and T-joint geometries. Both the butt joints and T-joints showed base material levels of strength. The mechanical performance of T-joints was also investigated using pull-out tests. The performance of the T-joints in such tests was sensitive to the shape and morphology of the welds. Fracture always occurred in the weld without any plastic deformation in the base material outside the weld.

Quantitative analysis of the orthodontic and orthopedic effects of maxillary traction.

PubMed

Baumrind, S; Korn, E L; Isaacson, R J; West, E E; Molthen, R

1983-11-01

This article analyzes differences in displacement of ANS and of the upper first molar when different vectors of force are delivered to the maxilla in non-full-banded Phase I mixed-dentition treatment of Class II malocclusion. The sample is identical to that for which we have previously reported differences in change in several key measures of mandibular and facial shape. It includes a cervical-traction group, a high-pull-to-upper-molar group, a modified-activator group, and an untreated Class II control group. Using newly developed computer-conducted procedures, which are described, we have been able to partition the orthodontic and orthopedic components of upper molar displacement and also to isolate treatment effects from those attributable to spontaneous growth and development. In the region of ANS, small but statistically significant and clinically meaningful differences were noted between treatments. When the intercurrent effects of growth and development had been factored out (Table III), orthopedic distal displacement of ANS was significantly greater in the high-pull and cervical groups than in the activator group. Orthopedic downward displacement of ANS was seen to be significantly greater in the cervical group than in the high-pull and activator groups. In the region of the first molar cusp, mean distal displacement of the tooth as an orthopedic effect was found to be almost identical in the cervical and high-pull groups (although variability was greater in the cervical group), but the mean orthodontic effect was significantly greater in the high-pull group than in the cervical group. In the cervical group, where relatively light forces were used for relatively long treatment periods on average, more of the total distal displacement of the upper molar was of an orthopedic character than of an orthodontic character. Conversely, in the high-pull group, in which relatively heavier forces tended to be used for briefer treatment periods, most of the distal displacement at the upper molar was of an orthodontic character. These observations are contrary to expectations from conventional orthodontic theory. In the activator-treated group, roughly equal components of the treatment-associated distal displacement of the upper molar were of the orthodontic and orthopedic types. As concerns changes in the vertical direction in the region of the molar cusp, significant intrusion of both the orthopedic and orthodontic types was seen in the high-pull sample as compared to each of the other groups examined.(ABSTRACT TRUNCATED AT 400 WORDS)

30 CFR 75.828 - Trailing cable pulling.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Trailing cable pulling. 75.828 Section 75.828... Longwalls § 75.828 Trailing cable pulling. The trailing cable must be de-energized prior to being pulled by... procedures must be followed when pulling the trailing cable with equipment other than the continuous mining...

Long-Term Outcome in Pediatric Trichotillomania

PubMed Central

Schumer, Maya C.; Panza, Kaitlyn E.; Mulqueen, Jilian M.; Jakubovski, Ewgeni; Bloch, Michael H.

2015-01-01

Objective To examine long-term outcome in children with trichotillomania. Method We conducted follow-up clinical assessments an average of 2.8 ± 0.8 years after baseline evaluation in 30 out of 39 children who previously participated in a randomized, double-blind, placebo-controlled trial of N-acetylcysteine (NAC) for pediatric trichotillomania. Our primary outcome was change in hairpulling severity on the Massachusetts General Hospital-Hairpulling Scale (MGH-HPS) between the end of the acute phase and follow-up evaluation. We also obtained secondary measures examining styles of hairpulling, comorbid anxiety and depressive symptoms, as well as continued treatment utilization. We examined both correlates and predictors of outcome (change in MGH-HPS score) using linear regression. Results None of the participants continued to take NAC at the time of follow-up assessment. No significant changes in hairpulling severity were reported over the follow-up period. Subjects reported significantly increased anxiety and depressive symptoms but improvement in automatic pulling symptoms. Increased hairpulling symptoms during the follow-up period were associated with increased depression and anxiety symptoms and increased focused pulling. Older age and greater focused pulling at baseline assessment were associated with poor long-term prognosis. Conclusions Our findings suggest that few children with trichotillomania experience a significant improvement in trichotillomania symptoms if behavioral treatments are inaccessible or have failed to produce adequate symptom relief. Our findings also confirm results of previous cross-sectional studies that suggest an increased risk of depression and anxiety symptoms with age in pediatric trichotillomania. Increased focused pulling and older age among children with trichotillomania symptoms may be associated with poorer long-term prognosis. PMID:26139231

Fluctuations uncover a distinct class of traveling waves

PubMed Central

Korolev, Kirill S.

2018-01-01

Epidemics, flame propagation, and cardiac rhythms are classic examples of reaction–diffusion waves that describe a switch from one alternative state to another. Only two types of waves are known: pulled, driven by the leading edge, and pushed, driven by the bulk of the wave. Here, we report a distinct class of semipushed waves for which both the bulk and the leading edge contribute to the dynamics. These hybrid waves have the kinetics of pushed waves, but exhibit giant fluctuations similar to pulled waves. The transitions between pulled, semipushed, and fully pushed waves occur at universal ratios of the wave velocity to the Fisher velocity. We derive these results in the context of a species invading a new habitat by examining front diffusion, rate of diversity loss, and fluctuation-induced corrections to the expansion velocity. All three quantities decrease as a power law of the population density with the same exponent. We analytically calculate this exponent, taking into account the fluctuations in the shape of the wave front. For fully pushed waves, the exponent is −1, consistent with the central limit theorem. In semipushed waves, however, the fluctuations average out much more slowly, and the exponent approaches 0 toward the transition to pulled waves. As a result, a rapid loss of genetic diversity and large fluctuations in the position of the front occur, even for populations with cooperative growth and other forms of an Allee effect. The evolutionary outcome of spatial spreading in such populations could therefore be less predictable than previously thought. PMID:29610340

Fluctuations uncover a distinct class of traveling waves.

PubMed

Birzu, Gabriel; Hallatschek, Oskar; Korolev, Kirill S

2018-04-17

Epidemics, flame propagation, and cardiac rhythms are classic examples of reaction-diffusion waves that describe a switch from one alternative state to another. Only two types of waves are known: pulled, driven by the leading edge, and pushed, driven by the bulk of the wave. Here, we report a distinct class of semipushed waves for which both the bulk and the leading edge contribute to the dynamics. These hybrid waves have the kinetics of pushed waves, but exhibit giant fluctuations similar to pulled waves. The transitions between pulled, semipushed, and fully pushed waves occur at universal ratios of the wave velocity to the Fisher velocity. We derive these results in the context of a species invading a new habitat by examining front diffusion, rate of diversity loss, and fluctuation-induced corrections to the expansion velocity. All three quantities decrease as a power law of the population density with the same exponent. We analytically calculate this exponent, taking into account the fluctuations in the shape of the wave front. For fully pushed waves, the exponent is -1, consistent with the central limit theorem. In semipushed waves, however, the fluctuations average out much more slowly, and the exponent approaches 0 toward the transition to pulled waves. As a result, a rapid loss of genetic diversity and large fluctuations in the position of the front occur, even for populations with cooperative growth and other forms of an Allee effect. The evolutionary outcome of spatial spreading in such populations could therefore be less predictable than previously thought. Copyright © 2018 the Author(s). Published by PNAS.

Coupled transport, mixing and biogeochemical reactions in fractured media: experimental observations and modelling at the Ploemeur fractured rock observatory

NASA Astrophysics Data System (ADS)

Le Borgne, T.; Bochet, O.; Klepikova, M.; Kang, P. K.; Shakas, A.; Aquilina, L.; Dufresne, A.; Linde, N.; Dentz, M.; Bour, O.

2016-12-01

Transport processes in fractured media and associated reactions are governed by multiscale heterogeneity ranging from fracture wall roughness at small scale to broadly distributed fracture lengths at network scale. This strong disorder induces a variety of emerging phenomena, including flow channeling, anomalous transport and heat transfer, enhanced mixing and reactive hotspot development. These processes are generally difficult to isolate and monitor in the field because of the high degree of complexity and coupling between them. We report in situ experimental observations from the Ploemeur fractured rock observatory (http://hplus.ore.fr/en/ploemeur) that provide new insights on the dynamics of transport and reaction processes in fractured media. These include dipole and push pull tracer tests that allow understanding and modelling anomalous transport processes characterized by heavy-tailed residence time distributions (Kang et al. 2015), thermal push pull tests that show the existence of highly channeled flow with a strong control on fracture matrix exchanges (Klepikova et al. 2016) and time lapse hydrogeophysical monitoring of saline tracer tests that allow quantifying the distribution of transport length scales governing dispersion processes (Shakas et al. 2016). These transport processes are then shown to induce rapid oxygen delivery and mixing at depth leading to massive biofilm development (Bochet et al., in prep.). Hence, this presentation will attempt to link these observations made at different scales to quantify and model the coupling between flow channeling, non-Fickian transport, mixing and chemical reactions in fractured media. References: Bochet et al. Biofilm blooms driven by enhanced mixing in fractured rock, in prep. Klepikova et al. 2016, Heat as a tracer for understanding transport processes in fractured media: theory and field assessment from multi-scale thermal push-pull tracer tests, Water Resour. Res. 52Shakas et al. 2016, Hydrogeophysical characterization of transport processes in fractured rock by combining push-pull and single-hole ground penetrating radar experiments, Water Resour. Res. 52 Kang et al. 2015, Impact of velocity correlation and distribution on transport in fractured media : Field evidence and theoretical model, Water Resour. Res., 51

Pressure-Distribution Measurements on O-2H Airplane in Flight

NASA Technical Reports Server (NTRS)

Pearson, H A

1937-01-01

Results are given of pressure-distribution measurements made over two different horizontal tail surfaces and the right wing cellule, including the slipstream area, of an observation-type biplane. Measurements were also taken of air speed, control-surface positions, control-stick forces, angular velocities, and accelerations during various abrupt maneuvers. These maneuvers consisted of push-downs and pull-ups from level flight, dive pull-outs, and aileron rolls with various thrust conditions. The results from the pressure-distribution measurements over the wing cellule are given on charts showing the variation of individual rib coefficients with wing coefficients; the data from the tail-surface pressure-distribution measurements are given mainly as total loads and moments. These data are supplemented by time histories of the measured quantities and isometric views of the rib pressure distributions occurring in abrupt maneuvers.

Anomalous Transport in Single-Well Push-Pull Tracer Tests

NASA Astrophysics Data System (ADS)

Chen, K.; Zhan, H.

2016-12-01

Single-Well Push-Pull (SWPP) tracer test was conducted to estimate the hydraulic and transport properties in a fractured aquifer at Newark basin. A common phenomenon observed for a set of SWPP tests with different incubation time is the heavy tailing of breakthrough curve (BTC) in pumping phase. A novel model with fractional-in-time and (or) -space was developed to interpret the anomalous transport behavior in SWPP tests. The fractal models, including fractional-in-time, fractional-in-space and fractional-in-time-and-space, were solved in radial coordinate using implicit Euler method. A semi-analytical solution of the mobile-immobile (MIM) model was derived as well for comparison purpose. It is found that the fractional-in-space and fractional-in-time-and-space models match the experimental data well. The BTC of the MIM model drops slower than that of the fractional-in-space model at the beginning of pumping and drops much faster at late time. The best match of fractional-in-space model with the experimental data demonstrates that the non-local transport in space plays an important role in SWPP tests conducted in fractured aquifers.

Nuclear transit study in children with chronic faecal soiling after Hirschsprung disease (HSCR) surgery has revealed a group with rapid proximal colonic treatment and possible adverse reactions to food.

PubMed

Stathopoulos, Lefteris; King, Sebastian K; Southwell, Bridget R; Hutson, John M

2016-08-01

Long-term problems with faecal incontinence occur in up to 50 % of patients after pull-through for Hirschsprung disease (HSCR). The cause often remains unknown, leading to empirical treatments. Using nuclear transit study, we found some patients surprisingly had rapid proximal colonic transit, suspicious of occult diarrhoea. We aimed to assess whether these patients had unrecognized adverse reactions to food. Patients (n = 10, all males, 9.6 year; 4.25-15.5 years) with persistent faecal incontinence following pull-through for HSCR referred to the senior author and after exclusion of anatomical defects, underwent nuclear transit studies. Most (8) subsequently underwent breath hydrogen tests for sugar malabsorption and were tested for adverse reactions to food. Exclusion diets for protein allergens, lactose or fructose were then trialed. Of the 10 patients with rapid intestinal transit proven on nuclear transit study, breath hydrogen tests for fructose and/or lactose malabsorption were done in 8, and were positive in 7/8 patients. Exclusion diets contributed to either resolution or improvement in faecal incontinence in 9/10 patients. Rapid transit in the proximal, ganglionated colon may be present in children with faecal incontinence following pull-through for HSCR, possibly secondary to adverse reactions to food. This study suggests that children with post-operative soiling may benefit from a transit study and hydrogen breath tests to diagnose adverse reactions to food caused by sugar malabsorption.

Evolution of Pull-Apart Basins and Their Scale Independence

NASA Astrophysics Data System (ADS)

Aydin, Atilla; Nur, Amos

1982-02-01

Pull-apart basins or rhomb grabens and horsts along major strike-slip fault systems in the world are generally associated with horizontal slip along faults. A simple model suggests that the width of the rhombs is controlled by the initial fault geometry, whereas the length increases with increasing fault displacement. We have tested this model by analyzing the shapes of 70 well-defined rhomb-like pull-apart basins and pressure ridges, ranging from tens of meters to tens of kilometers in length, associated with several major strike-slip faults in the western United States, Israel, Turkey, Iran, Guatemala, Venezuela, and New Zealand. In conflict with the model, we find that the length to width ratio of these basins is a constant value of approximately 3; these basins become wider as they grow longer with increasing fault offset. Two possible mechanisms responsible for the increase in width are suggested: (1) coalescence of neighboring rhomb grabens as each graben increases its length and (2) formation of fault strands parallel to the existing ones when large displacements need to be accommodated. The processes of formation and growth of new fault strands promote interaction among the new faults and between the new and preexisting faults on a larger scale. Increased displacement causes the width of the fault zone to increase resulting in wider pull-apart basins.

Evaluation of Static Friction of Polycrystalline Ceramic Brackets after Conditioning with Different Powers of Er:YAG Laser.

PubMed

Arash, Valiollah; Javanmard, Saeed; Eftekhari, Zeinab; Rahmati-Kamel, Manouchehr; Bahadoram, Mohammad

2015-01-01

This research aimed to reduce the friction between the wire and brackets by Er:YAG laser. To measure the friction between the wires and brackets in 0° and 10° of wire angulations, 40 polycrystalline ceramic brackets (Hubit, South Korea) were divided into 8 study groups and irradiated by 100, 200, and 300 mj/s of Er:YAG laser power. Two groups of brackets were not irradiated. The friction between the wires and brackets was measured with universal testing machine (SANTAM) with a segment of .019 × .025 SS wire pulled out of the slot of bracket. ANOVA and t-test were used for analyzing the results. To evaluate the effect of the laser on surface morphology of the bracket, SEM evaluations were carried out. The mean frictional resistances between the brackets and wires with 0° of angulation by increasing the laser power decreased compared with control group, but, in 10° of angulation, the friction increased regardless of the laser power and was comparable to the friction of nonirradiated brackets. Furthermore, with each laser power, frictional resistance of brackets in 10° of angulation was significantly higher than 0° of angulation. These results were explained by SEM images too.

Experimental Study of Boundary Layer Flow Control Using an Array of Ramp-Shaped Vortex Generators

NASA Technical Reports Server (NTRS)

Hirt, Stefanie M.; Zaman, Khairul B.M.Q.; Bencic, Tomothy J.

2012-01-01

The objective of this study was to obtain a database on the flowfield past an array of vortex generators (VGs) in a turbulent boundary layer. All testing was carried out in a low speed wind tunnel with a flow velocity of 29 ft/sec, giving a Reynolds number of 17,500 based on the width of the VG. The flowfield generated by an array of five ramp-shaped vortex generators was examined with hot wire anemometry and smoke flow visualization. The magnitude and extent of the velocity increase near the wall, the penetration of the velocity deficit into the core flow, and the peak streamwise vorticity are examined. Influence of various parameters on the effectiveness of the array is considered on the basis of the ability to pull high momentum fluid into the near wall region.

Comparison of the Hang High-Pull and Loaded Jump Squat for the Development of Vertical Jump and Isometric Force-Time Characteristics.

PubMed

Oranchuk, Dustin J; Robinson, Tracey L; Switaj, Zachary J; Drinkwater, Eric J

2017-04-15

Weightlifting movements have high skill demands and require expert coaching. Loaded jumps have a comparably lower skill demand, but may be similarly effective for improving explosive performance. The purpose of this study was to compare vertical jump performance, isometric force, and rate of force development (RFD) following a ten-week intervention employing the hang high-pull (hang-pull) or trap-bar jump squat (jump-squat). Eighteen NCAA Division II swimmers (8 males, 10 females) with at least one year of resistance training experience volunteered to participate. Testing included the squat jump (SJ), countermovement jump (CMJ) and the isometric mid-thigh pull (IMTP). Vertical ground reaction forces were analyzed to obtain jump height and relative peak power. Relative peak force, peak RFD and relative force at five time bands were obtained from the IMTP. Subjects were randomly assigned to either a hang-pull (n = 9) or jump-squat (n = 9) training group and completed a ten-week, volume-equated, periodized training program. While there was a significant main effect of training for both groups, no statistically significant between-group differences were found (p ≥ 0.17) for any of the dependent variables. However, medium effect sizes in favor of the jump-squat training group were seen in SJ height (d = 0.56) and SJ peak power (d = 0.69). Loaded jumps seem equally effective as weightlifting derivatives for improving lower-body power in experienced athletes. Since loaded jumps require less skill and less coaching expertise than weightlifting, loaded jumps should be considered where coaching complex movements is difficult.

Testing Machine for Biaxial Loading

NASA Technical Reports Server (NTRS)

Demonet, R. J.; Reeves, R. D.

1985-01-01

Standard tensile-testing machine applies bending and tension simultaneously. Biaxial-loading test machine created by adding two test fixtures to commercial tensile-testing machine. Bending moment applied by substrate-deformation fixture comprising yoke and anvil block. Pneumatic tension-load fixture pulls up on bracket attached to top surface of specimen. Tension and deflection measured with transducers. Modified test apparatus originally developed to load-test Space Shuttle surface-insulation tiles and particuarly important for composite structures.

Verbal Feedback in Therapeutic Communities: Pull-ups and Reciprocated Pull-ups as Predictors of Graduation

PubMed Central

Warren, Keith; Hiance, Danielle; Doogan, Nathan; De Leon, George; Phillips, Gary

2012-01-01

The most important proximal outcomes for residents of therapeutic communities (TCs) are retention and successful completion of the program. At this point there has been no quantitative analysis of the relationship between the exchange of corrective reminders, or pull-ups, between peers in TCs and graduation. This study draws on a database of pull-ups exchanged between 5,464 residents of three Midwestern TCs. Residents who send more pull-ups to peers and who reciprocate pull-ups with a larger percentage of peers are more likely to graduate. Residents who receive more pull-ups from peers and staff and a larger percentage of whose peers reciprocate pull-ups that they send are less likely to graduate. Implications of these findings for program theory and program improvement are discussed. PMID:23068980

Adhesion Strength Study of EVA Encapsulants on Glass Substrates

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

Pern, F. J.; Glick, S. H.

2003-05-01

An extensive peel-test study was conducted to investigate the various factors that may affect the adhesion strength of photovoltaic module encapsulants, primarily ethylene-vinyl acetate (EVA), on glass substrates of various laminates based on a common configuration of glass/encapsulant/backfoil. The results show that"pure" or"absolute" adhesion strength of EVA-to-glass was very difficult to obtain because of tensile deformation of the soft, semi-elastic EVA layer upon pulling. A mechanically"strong enough" backing foil on the EVA was critical to achieving the"apparent" adhesion strength. Peel test method with a 90-degree-pull yielded similar results to a 180-degree-pull. The 90-degree-pull method better revealed the four stages ofmore » delamination failure of the EVA/backfoil layers. The adhesion strength is affected by a number of factors, which include EVA type, formulation, backfoil type and manufacturing source, glass type, and surface priming treatment on the glass surface or on the backfoil. Effects of the glass-cleaning method and surface texture are not obvious. Direct priming treatments used in the work did not improve, or even worsened, the adhesion. Aging of EVA by storage over~5 years reduced notably the adhesion strength. Lower adhesion strengths were observed for the blank (unformulated) EVA and non-EVA copolymers, such as poly(ethylene-co-methacrylate) (PEMA) or poly(ethylene-co-butylacrylate) (PEBA). Their adhesion strengths increased if the copolymers were cross-linked. Transparent fluoropolymer superstrates such as TefzelTM and DureflexTM films used for thin-film PV modules showed low adhesion strengths to the EVA at a level of~2 N/mm.« less

Cassidy conducts MDCA Fuel Reservoir Remove and Replace OPS

NASA Image and Video Library

2013-04-10

ISS035-E-017699 (10 April 2013) --- This is one of several photos documenting the Multi-user Droplet Combustion Apparatus (MDCA) Fuel Reservoir replacement. Here, Expedition 35 Flight Engineer Chris Cassidy removes and replaces one of the Fuel Reservoirs with the MDCA Chamber Insert Assembly (CIA) pulled partially out of the Combustion Chamber. The MDCA Fuel Reservoirs contain the liquid fuel used during droplet combustion experiments. This reservoir change-out was in support of the FLame EXtinguishment (FLEX)-2 experiment, scheduled to be executed by ground controllers.

Cassidy conducts MDCA Fuel Reservoir Remove and Replace OPS

NASA Image and Video Library

2013-04-10

ISS035-E-017712 (10 April 2013)?-- This is one of several photos documenting the Multi-user Droplet Combustion Apparatus (MDCA) Fuel Reservoir replacement in the U.S. lab Destiny. Here, Expedition 35 Flight Engineer Chris Cassidy removes and replaces one of the Fuel Reservoirs with the MDCA Chamber Insert Assembly (CIA) pulled partially out of the Combustion Chamber. The MDCA Fuel Reservoirs contain the liquid fuel used during droplet combustion experiments. This reservoir change-out was in support of the FLame EXtinguishment (FLEX)-2 experiment, scheduled to be executed by ground controllers.