Water-filled Tube Research Articles

Comparison measurements of homogenized material properties of underwater acoustic metamaterials

A current area of research interest in acoustic metamaterials is the experimental validation of the effective properties computed using analytical and numerical models. This is generally done through an inverse measurement technique, by measuring the reflective and transmitted wave amplitudes and phases to calculate an effective impedance. When the background fluid used for this measurement is air, either an impedance tube or anechoic chamber can be utilized for these measurements. However, if the application of the metamaterial is for in-water applications, the measurement of these properties becomes much more difficult due to many complicating factors. Therefore, there has been little work obtaining homogenized, anisotropic material properties of underwater acoustic metamaterials. In this work, we present comparison of measurement methods of an acoustic metamaterial in an aqueous environment: a water-filled impedance tube and in a reverberant water tank. The metamaterial response will be predicted, and compared to the measurement in the impedance tube and reverberant tank. Additionally, trade-offs between the two experimental methods will be given.

An Automated Extracorporeal Knot-tying System Using Two Concentric Tube Robotic Arms for Deployment through a 3-mm Port

Ligation is a process of closing or blocking a blood vessel or duct intracorporeally to obstruct the flow of fluid before cutting it. Ligation through knot tying using a suture is a quite complex procedure and needs the use of dexterous tools to properly secure the knot. In case of natural orifice transluminal endoscopic surgery (NOTES) and single-incision laparoscopic surgery (SILS), ligation through suture knot tying is even more difficult because of the small diameters of the accessible ports. In this study, a robotic solution for suture ligation has been proposed for possible use in SILS and NOTES. The developed device can operate through a 3-mm laparoscopic port and has a workspace of 35 × 10x5 mm (length × width x height) around the duct. The device uses a pre-tied Roeder’s knot, which is pushed down onto the duct by the operation of two concentric tube-based manipulator arms. Preliminary evaluation validates that the device can work around a phantom duct with 7 mm outer diameter without any collisions. The operation takes an average of 128.10 s with a standard deviation of 15.72 s. The knot tied is secure enough to abduct the fluid flow inside the duct, which is validated by testing on a water-filled rubber tube. The proposed device assists surgeons for suture ligation in SILS and NOTES without the requirement for any other tools and with a possibility of decreasing the operating time.

Vibrations in a 7-rod bundle subject to axial flow: Simulations and experiments

Being able to quantify mechanical vibrations is of key importance for the safety of nuclear power plants, as they are able to induce damage. In this work, numerical simulations are used to compute water flow and vibration in a densely packed bundle of 7 rods, mimicking an experimental setup. This flow configuration is chosen to resemble the coolant flow through a nuclear reactor core. Because of the wall proximity, a considerable velocity difference between the narrow gaps and the subchannels exists, with an inflection point in the velocity profile. This yields an unstable situation, and large vortices are continuously created through a mechanism similar to the Kelvin–Helmholtz instability. The vortex streets in between the rods are associated with a fluctuating pressure field, causing vibrations of the rods.The experimental setup contains 7 steel cylinders, encased in a hexagonal duct. The central rod contains a section where the steel is replaced by a water-filled silicone tube, clamped at both extremes to the steel rod, and the vibrations of this section are examined. The numerical approach consists of coupled fluid–structure interaction (FSI) simulations, with the flow being modelled using computational fluid dynamics (CFD) and the structure using computational solid mechanics (CSM).The available experimental data consist of Laser Doppler Anemometry (LDA) measurements and high-speed camera footage of the wall movement of the silicone rod. Equivalent data is collected from the numerical simulations. The simulations are repeated for different flow rates. The frequency spectrum of the coherent structures, and the frequency and amplitude of the wall movement are compared for each operating point, as well as their trend as a function of the flow rate. The dominant frequencies found in the simulation results were similar to the experimental results, although slightly higher. They also showed a linear trend, just like the experiments. A larger mismatch was present for the structural response, the frequencies found using the FSI model being more than twice as high.

An illustration of the effect of neglecting poroelastic physics of water-saturated glass beads in a laboratory phase speed inference process.

The sound speed of sand has been shown to vary with frequency, yet in many instances in geoacoustic inversions, sand is modeled as a frequency-independent effective fluid. This paper investigates the effect to which assuming a frequency-independent fluid model that neglects poroelasticity can skew parameter estimation in a laboratory layered waveguide consisting of 1-mm diameter water-saturated glass beads (WSGBs), suspended in a water-filled glass tube. The phase speed in the waveguide was measured from 1 to 7 kHz and compared with phase speeds predicted in a finite element simulation of the experiment, where the WSGBs were treated as either a fluid with constant bulk density and frequency-independent or frequency-dependent sound speed, or by an effective density fluid model (EDFM) that includes poroelasticity. Measurement-simulation agreement occurred when using the EDFM to model the WSGB, although neglecting poroelasticity in the simulation only led to a maximum phase speed discrepancy of 8 m/s. However, this effect was significant when an inference process was used to determine the effective fluid properties of the WSGBs. Finally, high-frequency (150 to 450 kHz) direct sound speed measurements of the WSGB were obtained, and best matched the mid-frequency inference results obtained using the EDFM.

Innovative problem solving in great apes: the role of visual feedback in the floating peanut task

Nonhuman great apes show remarkable behavioural flexibility. Some individuals are even able to use water as a tool: They spit water into a vertical tube to make a peanut float upwards until it comes into reach (floating peanut task; FPT). In the current study, we used the FPT to investigate how visual feedback, an end-state demonstration and a social demonstration affect task performance in nonhuman great apes in three experiments. Our results indicate that apes who had acquired the solution with a clear tube maintained it with an opaque one. However, apes starting with an opaque tube failed to solve the task. Additionally, facing the peanut floating on a water-filled tube (i.e., an end-state demonstration) promoted success independent on the availability of visual feedback. Moreover, experiencing how water was poured into the tube either by a human demonstrator or by a water tap that had been opened either by the ape or a human did not seem to be of further assistance. First, this study suggests that great apes require visual feedback for solving the FPT, which is no longer required after the initial acquisition. Second, some subjects benefit from encountering the end-state, a finding corroborating previous studies.

Attenuation Coefficients of Tubular Conduits for Liquid Phase Absorbance Measurement: Shot Noise Limited Optimum Path Length.

We trace the history of liquid core waveguides (LCWs, also called liquid core optical fibers) and the role Teflon AF (TAF) has played in their development. We show that, in any shot noise limited situation, the optimum signal-to-noise ratio (S/N) occurs at a path length of 1/αa{ln[1 + 2(αa/αb)]}, approximately 2/αb under most conditions, αa and αb being the light attenuation coefficient due to the analyte and the background, respectively. The analysis shows that LCW length should be selected depending on the applicable αb value. An overly long LCW may exhibit a lower signal-to-noise ratio. Water-filled TAF-clad fused-silica (FS) tubes show the lowest attenuation across the wavelength range. Nevertheless, except at λ ≥ 600 nm, the observed αb values far exceed those reported for pure water: it appears that both impurities in the water and waveguide losses are involved. In examining the attenuation in various water-filled tubes, we find that the transmission of air-surrounded FS tubes is second only to TAF-clad FS tubes and is better than that of TAF tubes or externally mirrored FS tubes. Surprisingly, except for a window centered at ∼250 nm, light transmission in a water-filled poly(tetrafluoroethylene) (PTFE) tube is worse than in poly(ether ether ketone) (PEEK) tubing. Light transmission in PTFE tubes improves with increasing wall thickness.

Simulations for the explosion in a water-filled tube including cavitation using the SPH method

The damage to a structure due to an underwater explosion, which must necessarily include the phenomenon of cavitation, is a difficult problem to simulate. In this paper, the smoothed particle hydrodynamics (SPH) method is used to address the simulation of a fully explicit three-dimensional (3D) underwater explosion in a rigid or deformable cylinder, incorporating properly the physical phenomenon of cavitation. To this purpose, a general 3D SPH code has been implemented using the Open-MP programming interface. The various components of the code have been validated using four test cases, namely the Sjogreen test case for validation of the Riemann solver, the 1D cavitating flow in an open tube test case for validation of the cavitation model, the 1D pentaerythritol tetranitrate detonation test case for validation of the Jones–Wilkins–Lee model and a 3D high-velocity impact test case for validation of the elastic–perfectly plastic constitutive model. Following this validation, a 3D explosion within a water-filled rigid cylinder and a water-filled deformable aluminum tube are simulated with the general SPH code. The results of these simulations are compared against some available experimental data and some numerical simulations obtained using an alternative approach. These comparisons are generally in good agreement with both the experimental and numerical data, demonstrating that the SPH method can be used to simulate general 3D underwater explosion problems.

Measurement of additively manufactured anisotropic three-dimensional underwater pentamode materials

Pentamode (PM) materials are three-dimensional (3D) elastic lattice materials that can be designed to match the acoustic impedance of water while also minimizing shear modulus of the sample over wide frequency ranges. Further, the lattice structure provides the degrees of freedom necessary to produce strongly anisotropic stiffness that is useful for transformation acoustics [Su et al., J. Acoust. Soc. Am. 141(6) (2017)]. In the current work, anisotropic sub-wavelength 3D metallic PM samples were fabricated using additive manufacturing for measurement of their effective material properties. The samples were distributed uniformly in a one-dimensional, water-filled resonator tube. An electrodynamic shaker excited the system and the system response was recorded using a hydrophone positioned near the top of the tube. The resulting resonance frequencies were then used to infer the phase speeds for each mode in the fluid-filled elastic waveguide. Two effective medium models were used to infer the PM-water mixture properties: (i) Wood-Mallock mixture law and (ii) a self-consistent micromechanical model that explicitly considers material anisotropy. Experimental results are compared with simulations and observations are drawn on material property extraction using the resonance tube technique when elastic anisotropy is present. [Work supported by ONR.]

Testing the causal understanding of water displacement by kea (Nestor notabilis)

Abstract Rooks, Eurasian jays and NC crows have already solved the Aesop’s fable paradigm, using stones to raise a water level to get a previously out of reach reward. Here we test kea parrots on their understanding of water displacement. In Experiment 1, they preferentially chose the water-filled tube over two solid substrates (sand, rocks) within 5 trials. In Experiment 2, they generalised to novel coloured substrates in the first trial. In Experiment 3, confronted with two water-filled tubes, one of which was made unsolvable by preventing the water from rising, none of the kea managed to solve the task. This suggests that their performance in Experiments 1 and 2 was reward association with the liquid-filled tube, without attendance to changes in water level. These results therefore provide no evidence of causal understanding of water displacement and highlight that such an understanding is not required for solving Aesop’s Fable.

Hemostatic Effect of the Combination of Factor VIII Concentrate with Tranexamic Acid (TXA) in the Prophylactic Setting in Severe Hemophilia a

IntroductionHemophilia is an X linked disorder characterized by an increased tendency to spontaneous bleeding resulting from profound compromise of the hemostatic response with delayed development of a clot and the formation of clots that are vulnerable to fibrinolysis. Optimization of clot stability by adding TXA to low concentrations of factor concentrates may be a way to improve prophylaxis in patients with severe hemophilia (sH) without substantially increasing the cost or the burden of more frequent infusions.AimsWe proposed to study whether hemostasis is improved with the addition of TXA to low FVIII plasma concentrations (equivalent to trough levels in prophylactic setting). We specifically studied in vitro the clot stability in patients with sHA; and in vivo the hemostatic response to trauma-induced joint bleed and tail clip in FVIII knock-out (KO) mice.MethodsAfter obtaining informed consent, blood samples of 12 adults with sHA were spiked in vitro to achieve final concentrations (FC) of 0-3-10 and 30 IU/dL of FVIII, then studied with and without TXA at FC 0.1mg/ml. Whole blood (WB) was assessed with ROTEM performed after addition of tPA in 6 patients. Thrombin generation (TG) was measured in plasma (PL) of 6 other patients. Clots obtained from TG were examined under electron microscopy (EM) to evaluate the quality of fibrin clot structure. Diameters of randomly selected 100 fibrin fibers were measured in each clot.In animal studies, 13 FVIII KO mice were given FVIII to a plasma concentration of 3 IU/dL to mimic trough FVIII levels in prophylactic setting; 7 were also infused with TXA (FC 0.1mg/ml). 10 minutes after infusion, joint bleeding was induced by knee puncture using a standardized protocol. 2 days post trauma, MRI was done and the joint bleed (surface of hyper signal into the joint) was compared between the groups with and w/o TXA.10 other FVIII KO mice were infused with 3 IU/dL rFVIII, of which 5 were also infused with TXA (FC 0.1mg/ml). 10 minutes after infusion, the extremity of the tail was cut at 2mm, and then immersed in pre-heated water-filled tube at 37°C. Blood was collected during 10 minutes. After lysis of erythrocytes, the amount of hemoglobin in collected blood was measured using spectrophotometry; means of optical density (OD) were compared between the 2 groups.ResultsA dose dependent improvement of TG was observed after adding FVIII alone (p=0.024). As expected, the addition of TXA had no effect on TG capcity. Fibrin fiber diameters were significantly decreased with TXA+FVIII compared to FVIII alone (results shown in fig1), suggesting a stronger fibrin network, as thin fibrin fibers are characteristic of a robust fibrin mesh. Surprisingly, ROTEM was fully normalized after addition of TXA only, with no exogenous FVIII.In FVIII KO mice, the addition of TXA to 3 IU/dL rFVIII significantly decreased joint bleeding compared to 3 IU/dL rFVIII alone (p=0.022) (fig2).With the tail clip experiment, the addition of TXA to 3 IU/dLFVIII showed a trend toward improved bleeding when compared to 3 IU/dLFVIII alone; with means of OD±SEM 0,31±0,19 and 0,94±0,45 respectively, but did not reach statistical significance (p=0,15) (fig3).ConclusionOur in vitro and in vivo results suggest a potential benefit of TXA when used in combination with FVIII in prophylactic setting. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Application of the Runge Kutta Discontinuous Galerkin-Direct Ghost Fluid Method to internal explosion inside a water-filled tube

This paper aims to assess the applicability of the Runge Kutta Discontinuous Galerkin-Direct Ghost Fluid Method to the internal explosion inside a water-filled tube, which previously was studied by many researchers in separate works. Once the explosive charge located at the inner center of the water-filled tube explodes, the tube wall is subjected to an extremely high intensity fluid loading and deformed. The deformation causes a modification of the field of fluid flow in the region near the water-structure interface so that has substantial influence on the response of the structure. To connect the structure and the fluid, valid data exchanges along the interface are essential. Classical fluid structure interaction simulations usually employ a matched meshing scheme which discretizes the fluid and structure domains using a single mesh density. The computational cost of fluid structure interaction simulations is usually governed by the structure because the size of time step may be determined by the density of structure mesh. The finer mesh density, the better solution, but more expensive computational cost. To reduce such computational cost, a non-matched meshing scheme which allows for different mesh densities is employed. The coupled numerical approach of this paper has fewer difficulties in the implementation and computation, compared to gas dynamics based approach which requires complicated analytical manipulations. It can also be applied to wider compressible, inviscid fluid flow analyses often found in underwater explosion events.

Effect of positioning on ureteric stone retropulsion: ‘gravity works’

To evaluate the potential impact of alterations in 'patient' position on laser-induced ureteric stone retropulsion in an in vitro model. A ceramic (phantom) stone was placed in a water-filled clear polymer tube and subjected to continuous laser energy until the stone had retropulsed a distance of 10 cm. The trial was stopped after 60 s if the stone had not reached 10 cm. The time and total energy needed to cause 10 cm of retropulsion were recorded at incline angles of 0°, 10°, 20°, and 40°; 10 trials at each angle were completed. The study was then repeated with pure calcium phosphate brushite stones. Retropulsion decreased with increasing incline angle of the saline-filled clear polymer tube. At 0° of incline the phantom stone reached a distance of 10 cm after 7.4 s. At 10°, 20° and 40°, the phantom stone migrated a mean maximum distance of 3.1, 1.2 and 0.7 cm, respectively, and the trial was stopped after 60 s. For the calcium phosphate stone, at 0° and 10° of incline, the stone reached 10 cm after 6.9 and 42.8 s, respectively (P < 0.05). At 20° and 40°, the calcium phosphate stone moved a mean maximum distance of 2.4 and 1 cm, and the trial was stopped after 60 s. Alterations in the angle of inclination reduced stone retropulsion during ureteroscopic lithotripsy in an in vitro model to <1 cm. Increasing the incline angle of a patient may effectively preclude retropulsion when performing laser lithotripsy of ureteric stones.

Predictive modelling of supercritical CO2 dewatering of capillary tubes

Supercritical CO2 can be used to mechanically dewater porous materials by expelling moisture via gas bubble pressure and buoyancy during depressurisation. We have developed an Ansys Fluent™ fluid dynamics model to predict the behaviour of the supercritical CO2 dewatering process. This complex model combines the Multiphase Euler-VOF solution method with Interfacial-Area Species-Transport mechanism and user defined functions for non-linear Henry’s law and mixture density. We have effectively modelled dewatering as a series of 40 mm long, water-filled capillary tubes, with internal diameters ranging from 0.1 to 10 mm. The model predicts experimental results well. The mass transfer coefficient required an additional empirical dispersion term, approximately 80 times that of diffusion, when the characteristic Bond number is greater than unity and viscous forces are greater than surface tension forces. The model will contribute to the understanding of fundamental dewatering behaviour and assist with supercritical dewatering plant design.

5.04% system slope efficiency solar-pumped Nd:YAG laser by a heliostat–parabolic mirror system

We demonstrated a solar-pumped laser with a heliostat–parabolic mirror system. A designed conical pump cavity with a water-filled quartz tube lens was used to couple efficiently the concentrated solar radiation from the focal zone of the primary concentrator into a 5.5-mm-diameter, 95-mm-length grooved Nd:YAG crystal rod within a gold-plated conical pump cavity. For 1.0-m2 effective solar radiation collection area, 20.1-W continuous-wave (CW) output laser power was obtained, corresponding to a total system slope efficiency of 5.04%. This value was 1.31 times higher than the previous with the same solar facility. For 1.5-m2 effective collection area, 34.6-W CW output laser power was achieved at the total system slope efficiency of 4.51%. A strong dependency of laser power on laser rod mounting position was also found.

Compensatory Muscle Activation During Unstable Overhead Squat Using a Water-filled Training Tube.

Glass, SC, and Albert, RW. Compensatory muscle activation during unstable overhead squat using a water-filled training tube. J Strength Cond Res 32(5): 1230-1237, 2018-The purpose of this study was to assess compensatory muscle activation of core and support muscle during an overhead squat using a water-filled training tube. Eleven experienced weightlifting (age = 20.10 ± 0.99, mass 89.17 ± 6.88 kg) men completed 3, 30-second trials of an overhead squat using an 11.4 kg tube that was partially filled with water. A central valve allowed 3 conditions of water movement: 50% open, 100% open, and a stable(S), closed valve condition. Subjects completed 8-10 repetitions within each condition. Electromyographic (EMG) electrodes were placed over the belly of the vastus lateralis, deltoid, rectus abdominus, and paraspinal muscles and recorded during concentric and eccentric (ECC) phases. Integrated EMG were computed and converted to percent maximal voluntary contraction (%MVC). Compensatory activation was assessed using the natural log of the coefficient of variation of %MVC across repetitions. A 1-way repeated-measures analysis of variance across (phase, condition) was used. Significant compensatory muscle activation was seen in the deltoid muscle during ECC (100% open = 3.60 ± 0.50 > stable LogCV = 3.06 ± 0.45). In addition, paraspinal muscle activity was also more variable during the ECC phase (50% open LogCv = 3.28 ± 0.26 > stable = 2.77 ± 0.67). We conclude that the water-filled training tube induces compensatory muscle activation in the deltoid and paraspinal muscles during the ECC phase of the overhead squat.

Performance of the fiber-optic low-coherent ground settlement sensor: From lab to field.

A fiber-optic low-coherent interferometry sensor was developed to measure the ground settlement (GS) in an accuracy of the micrometer. The sensor combined optical techniques with liquid-contained chambers that were hydraulically connected together at the bottom by using a water-filled tube. The liquid surface inside each chamber was at the same level initially. The optical interferometry was employed to read out the liquid level changes, which following the GS happened at the place where the chamber was put on and, thereby, the GS information was calculated. The laboratory effort had demonstrated its potential in the practical application. Here, the denoising algorithms on the measurement signal were carried out based on the specific environment to ensure the accuracy and stability of the system in field applications. After that, we extended this technique to the high-speed railway. The 5-days continuous measurement proved that the designed system could be applied to monitor the GS of the high-speed railway piers and approached an accuracy of ±70 μm in the field situation with a reference compensation sensor. So the performance of the sensor was suitable to the GS monitoring problem in the high-speed railway. There, the difficulties were to meet the monitoring requirement of both a large span in space and its quite tiny and slow changes.

Water-filled training tubes increase core muscle activation and somatosensory control of balance during squat

ABSTRACTThis study examined trunk muscle activation, balance and proprioception while squatting with a water-filled training tube (WT) and a traditional barbell (BB), with either closed (CE) or open eyes (OE). Eighteen male elite Gaelic footballers performed an isometric squat under the following conditions: BB-OE, BB-CE, WT-OE and WT-CE. The activity of rectus abdominis (RA), external oblique (EO) and multifidus (MF) was measured using electromyography, along with sway of the centre of pressure (CoP) using a force platform. Only the EO and the MF muscles exhibited an increased activity with WT (p < 0.01). In the medio-lateral direction both the velocity and range of the CoP increased significantly with WT (p < 0.01). Interestingly, the range of the CoP for the WT-CE condition was significantly lower than WT-OE (p < 0.05, d = 0.44), whilst the velocity of the CoP was marginally reduced (d = 0.29). WT elicited a greater level core muscle activation and created a greater challenge to postural stability when compared to a BB. It appears that WT does not benefit from vision but emphasises the somatosensory control of balance. The use of WT may be beneficial in those sports requiring development of somatosensory/proprioceptive contribution to balance control.

Young children do not require perceptual-motor feedback to solve Aesop's Fable tasks.

Aesop’s Fable tasks—in which subjects drop objects into a water-filled tube to raise the water level and obtain out-of-reach floating rewards —have been used to test for causal understanding of water displacement in both young children and non-human animals. However, a number of alternative explanations for success on these tasks have yet to be ruled out. One hypothesis is that subjects may respond to perceptual-motor feedback: repeating those actions that bring the reward incrementally closer. Here, we devised a novel, forced-choice version of the Aesop’s Fable task to assess whether subjects can solve water displacement tasks when this type of feedback is removed. Subjects had to select only one set of objects, or one type of tube, into which all objects were dropped at once, and the effect the objects had on the water level was visually concealed. In the current experiment, fifty-five 5–9 year old children were tested in six different conditions in which we either varied object properties (floating vs. sinking, hollow vs. solid, large vs. small and too large vs. small objects), the water level (high vs. low) and/or the tube size (narrow vs. wide). We found that children aged 8–9 years old were able to solve most of the water displacement tasks on their first trial, without any opportunity for feedback, suggesting that they mentally simulated the results of their actions before making a choice. Children aged 5–7 years solved two conditions on their first trial (large vs. small objects and high- vs. low-water levels), and learnt to solve most of the remaining conditions over five trials. The developmental pattern shown here is comparable to previous studies using the standard Aesop’s Fable task, where eight year olds are typically successful from their first trial and 5–7 year olds learn to pass over five trials. Thus, our results indicate that children do not depend on perceptual-motor feedback to solve these water displacement tasks. The forced-choice paradigm we describe could be used comparatively to test whether or not non-human animals require visual feedback to solve water displacement tasks.

Performance in Object-Choice Aesop's Fable Tasks Are Influenced by Object Biases in New Caledonian Crows but not in Human Children.

The ability to reason about causality underlies key aspects of human cognition, but the extent to which non-humans understand causality is still largely unknown. The Aesop’s Fable paradigm, where objects are inserted into water-filled tubes to obtain out-of-reach rewards, has been used to test casual reasoning in birds and children. However, success on these tasks may be influenced by other factors, specifically, object preferences present prior to testing or arising during pre-test stone-dropping training. Here, we assessed this ‘object-bias’ hypothesis by giving New Caledonian crows and 5–10 year old children two object-choice Aesop’s Fable experiments: sinking vs. floating objects, and solid vs. hollow objects. Before each test, we assessed subjects’ object preferences and/or trained them to prefer the alternative object. Both crows and children showed pre-test object preferences, suggesting that birds in previous Aesop’s Fable studies may also have had initial preferences for objects that proved to be functional on test. After training to prefer the non-functional object, crows, but not children, performed more poorly on these two object-choice Aesop’s Fable tasks than subjects in previous studies. Crows dropped the non-functional objects into the tube on their first trials, indicating that, unlike many children, they do not appear to have an a priori understanding of water displacement. Alternatively, issues with inhibition could explain their performance. The crows did, however, learn to solve the tasks over time. We tested crows further to determine whether their eventual success was based on learning about the functional properties of the objects, or associating dropping the functional object with reward. Crows inserted significantly more rewarded, non-functional objects than non-rewarded, functional objects. These findings suggest that the ability of New Caledonian crows to produce performances rivaling those of young children on object-choice Aesop’s Fable tasks is partly due to pre-existing object preferences.

Core Muscle Activation During Unstable Bicep Curl Using a Water-Filled Instability Training Tube.

Glass, SC, Blanchette, TW, Karwan, LA, Pearson, SS, O'Neil, AP, and Karlik, DA. Core muscle activation during unstable bicep curl using a water-filled instability training tube. J Strength Cond Res 30(11): 3212-3219, 2016-The purpose of this study was to assess compensatory muscle activation created during a bicep curl using a water-filled, unstable lifting tube. Ten men (age = 21 ± 1.6 years, height = 180.0 ± 3.3 cm, mass = 87.4 ± 15.0 kg) and 10 women (age = 19.6 ± 1.3 years, height = 161.4 ± 12.0 cm, mass = 61.2 ± 7.4 kg) completed bicep curls using an 11.4-kg tube partially filled with water during a 50% open-valve, 100% open, and control setting. Subjects completed 8 repetitions within each condition with integrated electromyographic signal (converted to percent maximal voluntary contraction) of the bicep, deltoid, rectus abdominus, and paraspinal muscles measured. Compensatory activation was determined using the natural log of coefficient of variation across concentric (CON) and eccentric (ECC) contractions. There were no differences between gender for any condition. Significant variability was seen across treatments for paraspinal muscles for CON and ECC at 50% (CON LnCV = 3.13 ± 0.56%, ECC LnCV = 3.34 ± 0.58%) and 100% (CON = 3.24 ± 0.34%, ECC = 3.46 ± 0.35%) compared with control (CON = 2.59 ± 0.47%, ECC = 2.80 ± 0.61%). Deltoid variability was greater at the 100% open setting (CON = 3.51 ± 0.53%, ECC = 3.56 ± 0.36%) compared with control (CON = 2.98 ± 0.35%, ECC = 2.97 ± 0.45%). The abdominal CON 100% showed variability (3.02 ± 0.47%) compared with control (2.65 ± 0.43%). Bicep activation remained unvaried. Compensatory activation of postural muscles contribute to postural stability. This device may be a useful tool for neuromuscular training leading to improved stability and control.