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Current study was set to determine the impact of active smoking on Achilles Tendon (AT) as soft tissue using an elastographic technique. This study comprises of 54 male individuals having sedentary lifestyle. Volunteers were categorized into two groups of smokers (n = 20) and non-smokers (n = 34). Body composition analysis was performed to evaluate the physiological changes in human body mass indexes. Ultrasound Strain Elastog-raphy (USE) technique was used to find the stiffness along with anatomical images to envisage the anomalous status of Achilles tendon. Statistical analysis of data obtained through body composition, tendon anatomy and Strain Elastography (SE) was used to scrutinize the physiological, anatomical and elasticity variations within the tendon. A reduction in Fat Free Mass Index (FFMI) was observed among smokers with a significant difference (P = 0.042). Further, an increased significant difference (P = 0.029) was found in AT Strain Ratios (SR) of smokers as compared to non-smokers. Lightening in tendon mass and dilution in tendon stiffness indicates that smoking mechanism may generate excessive apoptosis and decrease the density of tenocytes. Nicotine is the key element that inhibits the functional capacity of Tendon Stem Cells and is highly responsible for tendinopathy, eventually leading to tendon rupture and injury.

The depth dependent UV-light absorption profile of GaN nanorods with different lattice arrays and filling factors was studied using finite-difference time-domain (FDTD) methods. By comparing to the results from Lambert-Beer's law with Maxwell-Garnett effective medium theory, we identified the quantitative contribution from nano-scattering effect on the light absorption in the nanorod arrays. The FDTD study of graphical 3D profile of light absorption and electric field intensity was parallelly conducted to investigate the origin of the nano-scattering. We found that the coupled electric field in the gap regions led to the larger absorption cross-section of the nanorod arrays, which is attributed to the distorted depth profile of the light absorption.

Defects at the bulk grain boundaries and heterojunction interfaces could dictate the power losses of perovskite solar cells (PSCs) during the operation process, which are regarded as major roadblocks towards further development of this emerging photovoltaic technology. The common modulation strategies reported for the state-of-the-art cells cannot concurrently heal the defects located at the grain boundaries and interfaces. Herein, a depth-dependent manipulation strategy is demonstrated to concurrently modulate the bulk and interfacial defects in the perovskite films. According to the distinct penetrability of the employed binary modulators within the polycrystalline perovskite film, one of the modulators can penetrate through the bulk to the buried interface, accompanied by bulk and buried interface defect healing, while the other remains to anchor atop the surface along with the surface defect modulation, assuring simultaneous defect management from the interfaces to the bulk. As a result, the mitigated non-radiative losses and the improved charge transport of the modulated perovskite film boost the efficiency of PSCs from 21.79% to 24.36%. This universally effective depth-dependent manipulation strategy provides new insights into spatial defect modulation, which would open up a promising way for defect modulator design for highly efficient perovskite optoelectronic devices.

The inverse problem of electrical impedance tomography is severely ill-posed. In particular, the resolution of images produced by impedance tomography deteriorates as the distance from the measurement boundary increases. Such depth dependence can be quantified by the concept of distinguishability of inclusions. This paper considers the distinguishability of perfectly conducting ball inclusions inside a unit ball domain, extending and improving known two-dimensional results to an arbitrary dimension $d \geq 2$ with the help of Kelvin transformations. The obtained depth-dependent distinguishability bounds are also proven to be optimal., 20 pages, 2 figures

Offshore geoengineering requires reliable sediment parameters for analysis and design. This study proposes a robust framework for effective stress-dependent geotechnical and geoacoustic pro...

PURPOSE To determine the impact of corneal crosslinking (CXL) performed over the laser in situ keratomileusis (LASIK) flap using the Standard CXL (S-CXL) protocol or under the flap after flap lift (flap-CXL) on regional corneal stiffness using Brillouin microscopy. SETTING University of Southern California Keck School of Medicine, Los Angeles, California, and Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA. DESIGN Laboratory ex vivo experiment. METHODS After epithelium debridement, LASIK flaps were created on intact fresh porcine eyes with a mechanical microkeratome. Then, S-CXL (riboflavin applied to the corneal surface followed by 3 mW/cm ultraviolet exposure with the flap in place for 30 minutes) or flap-CXL (riboflavin applied to the stromal bed after reflecting the flap followed by the same ultraviolet A exposure with the flap replaced) was performed. Depth profile of stiffness variation and averaged elastic modulus of anterior, middle, and posterior stroma were determined by analyzing Brillouin maps. Each eye served as its own control. RESULTS The study was performed on 24 fresh porcine eyes. S-CXL had maximal stiffening impact in the anterior most corneal stroma within the LASIK flap (8.40 ± 0.04 GHz), whereas flap-CXL had lower maximal stiffening impact (8.22 ± 0.03 GHz) (P < .001) that occurred 249 ± 34 μm under the corneal surface. S-CXL increased longitudinal modulus by 6.69% (anterior), 0.48% (middle), and -0.91% (posterior) as compared with flap-CXL, which increased longitudinal modulus by 3.43% (anterior, P < .001), 1.23% (middle, P < .1), and -0.78% (posterior, P = .68). CONCLUSIONS The S-CXL technique generated significantly greater stiffening effect in the anterior cornea than a modified protocol with riboflavin administration under the flap (flap-CXL). Minimal stiffening occurred in the middle or posterior cornea with either protocol.

Objectives To determine if the depth of corticotomy done with the piezoelectric knife could play a role in the intensity of the regional acceleratory phenomenon (RAP). Materials and Methods Eighteen Sprague-Dawley rats were divided into two groups: untreated (3 rats) and treatment (15 rats). In the treatment group, a split-model design was used. The right tibia received transcortical (deep) penetrations with the piezoelectric knife, while intracortical (shallow) penetrations were performed on the left tibia of the same animal. The rats were euthanized at day 1, 3, 7, 14, and 28. Cone-beam computed tomography scans were taken for each sample and then assessed by histological analysis. Results Higher amounts of osteoclastic activity and new collagen formation were observed in the deep penetration group when compared with the shallow penetration group. The former peaked at day 14 for both groups (1.53% ± 0.01% vs 0.03% ± 0.0004%, respectively), and the latter peaked at day 28 (0.65 × 106 ± 0.01 vs 0.08 × 106 ± 0.0008, respectively). Conclusions Within the limitations of this study, it appears that the intensity of the RAP in the rat is corticotomy depth dependent. This is to be kept in mind when decorticating the bone during surgically facilitated orthodontic procedures.

Background:Preservation of residual hearing is one of the major goals in modern cochlear implant surgery. Intra-cochlear fluid pressure changes influence residual hearing, and should be kept low before, during and after cochlear implant insertion.Methods:Experiments were performed in an artificial cochlear model. A pressure sensor was inserted in the apical part. Five insertions were performed on two electrode arrays. Each insertion was divided into three parts, and statistically evaluated in terms of pressure peak frequency and pressure peak amplitude.Results:The peak frequency over each third part of the electrode increased in both electrode arrays. A slight increase was seen in peak amplitude in the lateral wall electrode array, but not in the midscalar electrode array. Significant differences were found in the first third of both electrode arrays.Conclusion:The midscalar and lateral wall electrode arrays have different intra-cochlear fluid pressure changes associated with intra-cochlear placement, electrode characteristics and insertion.

For the reconstruction of the microvasculature from contrast-enhanced ultrasound sequences with ultrasound localization microscopy, it is neccessary that a vessel is flown through by at least one microbubble (MB). Therefore, the reconstruction degree can be increased by either long acquisition times or by using high MB concentrations. However, in clinical applications the measurement times are usually limited. Thus, an adequate method for the detection of the MB is essential that ensures an accurate localization of single MB even in case of overlaying point-spread functions (PSFs) when using high MB concentrations. Therefore, we investigated the performance of sparsity based ultrasound hemodynamic super-resolution (SUSHI), and also expanded it to depth dependent PSFs. We applied the method to varying MB concentrations, analyzed different implementations of SUSHI and compared it to standard detection methods (Gauss detection and the centroid detection). The sparsity driven super-resolution with depth dependent PSFs showed the highest sensitivity for high MB concentrations. The Gauss detection yielded the lowest error rates. The centroid detection failed with increasing MB concentration.

3D Single molecule localization microscopy relies on fitting of the individual molecules with a point spread function (PSF) model. The reconstructed images often show local squeezing or expansion in z. A common cause are depth-induced aberrations in conjunction with an imperfect PSF model calibrated from beads on a coverslip, resulting in a mismatch between measured PSF and real PSF. Here, we developed a strategy for accurate z-localization in which we use the imperfect PSF model for fitting, determine the fitting errors and correct for them in a post-processing step. We present an open-source software tool and a simple experimental calibration procedure that allow retrieving accurate z-positions in any PSF engineering approach or fitting modality, even at large imaging depths.

The biomechanical characteristics of porcine corneal stroma along the depth of cornea in different anatomical orientations were experimentally investigated and quantitatively analyzed. The porcine corneal stroma tested here was cut mechanically into the three layers along the thickness of the cornea for the first time. Based on the convenient uniaxial tensile extensometry, the Young’s moduli of each stromal layer in different anatomical orientations were proved to be equal to each other. By virtue of testing the mechanical behaviors of the different layers, the Young’s moduli of the stromal layers were found to decrease gradually from the anterior to posterior corneal surface. Thus, the stroma was proved to be mechanically transversely isotropic. Furthermore, based on the analysis of the experimental data, the change of stromal Young’s modulus along the depth of the cornea was determined to be linear and equal to - 2.79 ± 0.967 MPa/mm from the anterior to posterior corneal surface. Finally, the li...

Impulsive signals generated by the implosion of an incandescent light bulb were measured in shallow water with implosion depths in the range of 10 – 80 m. The received waveform was characterized by successive negative and positive pressure pulses originating from the bubble oscillation process. The time intervals between successive bubble pulses decreased with increasing implosion depth and the peaks of subsequent bubble oscillations dissipated relatively quickly. In this paper, semi-empirical formulas are derived to model the depth-dependent characteristics of the bulb implosion signal, including the time interval between bubble pulses and peak source level. The model predictions are compared with the measured signals and with the results in the literature. Possible causes of the differences in the comparison with previous results are discussed.

The anatomical arrangement of the Achilles tendon (AT), with distinct fascicle bundles arising from the gastrocnemius and soleus muscles, may facilitate relatively independent behavior of the triceps surae muscles. A reduced capacity for sliding between adjacent tendon fascicles with age may couple gastrocnemius and soleus muscle behavior, thereby potentially contributing to diminished plantarflexor performance commonly observed in old adults. Nine healthy young (mean age, 23.9 yr) and eight healthy old (69.9 yr) adults walked at three speeds (0.75, 1.00, and 1.25 m/s) on a force-sensing treadmill. We coupled dynamic ultrasound imaging of the free AT with motion capture and inverse dynamic analyses to compute, in part: 1) depth-dependent variations in AT tissue displacements and elongations and 2) net ankle joint kinetics during push-off. The difference in displacements between superficial and deep AT regions, and in their corresponding elongations, did not differ between old and young adults at the slower two walking speeds ( P > 0.61). However, old adults walked with 41% smaller depth-dependent variations in free AT displacements and elongations at 1.25 m/s ( P = 0.02). These more uniform tendon deformations in old adults most strongly correlated with reduced peak ankle moment ( R2= 0.40), but also significantly correlated with reduced peak power generation ( R2= 0.15) and positive ankle work during push-off ( R2= 0.19) ( P > 0.01). Our findings: 1) demonstrate a potential role for nonuniform AT deformations in governing gastrocnemius and soleus muscle-tendon function and 2) allude to altered tendon behavior that may contribute to the age-related reduction in plantarflexor performance during walking.

This paper presents a material classification method using an off-the-shelf Time-of-Flight (ToF) camera. We use a key observation that the depth measurement by a ToF camera is distorted in objects with certain materials, especially with translucent materials. We show that this distortion is caused by the variations of time domain impulse responses across materials and also by the measurement mechanism of the existing ToF cameras. Specifically, we reveal that the amount of distortion varies according to the modulation frequency of the ToF camera, the material of the object, and the distance between the camera and object. Our method uses the depth distortion of ToF measurements as features and achieves material classification of a scene. Effectiveness of the proposed method is demonstrated by numerical evaluation and real-world experiments, showing its capability of even classifying visually similar objects.

The effect of strain gradient on the mechanical property of a material is implemented through a depth-dependent stress strain relation model in conventional finite element simulations for use in friction prediction. For the incorporation of a strain gradient effect, contact simulation involving asperities was developed with the assumption that the deformation pattern created by asperities from the tool surface in microforming is comparable to the deformation created by the indenter in a hardness test. Consequently, a depth-dependent stress-strain relation was derived from the indentation size effect model and this stress-strain relation was used in a simulation to show the effect of strain gradient on friction behaviour in microforming at different surface roughness levels. An experiment was conducted alongside the simulation and the results showed that with asperity ploughing considered as the major contributor to friction in microforming at room temperature, the simulation involving depth-dependent material properties is able to better predict the friction behaviour as compared to its continuum simulation counterpart. © 2014 Elsevier Ltd. All rights reserved. ispartof: International Journal of Mechanical Sciences vol:86 pages:46-53 status: published

This work presents new calibration procedures for deep elemental depth profile analysis of bronze artifacts. A simple ablation model is developed for the estimation of the ablation rate and hence for deriving the depth spatial calibration scale. Elemental quantification is obtained through the construction of calibration surfaces, using reference samples of known composition, relating laser-induced plasma spectroscopy (LIPS) intensity ratios, content of atomic species and number of laser pulses. Such a method represents a refinement of the standard LIPS quantification approach based on calibration curves, which is extended here to the generation of significantly deep craters into the material under investigation up to several hundred microns. The depth dependence of the calibration surfaces measured is discussed in the framework of a simplified model of depth-dependent plasma temperature.

We have developed a kinematic fault network model of crustal deformation in an elastic half-space. Surface deformation is calculated using this model assuming each fault segment slipping beneath a locking depth. Each fault segment connects to its adjacent elements with slip vector continuity imposed at fault nodes or intersections; the degree of the constraints determines whether deformation is block-like or not. We apply this model to invert GPS observations for slip rates on major faults in California with geological rate constraints. Based on the F-test result, we find that lesser block-like models fit the data significantly better than the strictly block-like model. Our final inversion shows a slip rate varying from 20 to 23 mm/yr along the northern San Andreas from the Santa Cruz to the North Coast segment. Slip rates vary from 9 to 13 mm/yr along the Hayward to the Maacama fault segment, and from 15 to 3 mm/yr along the central Calaveras to the West Napa fault segment. For the central California Creeping Zone, the result suggests a depth dependent creep rate with an average of 22 mm/yr over the top 5 km and 32 mm/yr underneath. From the Mojave to San Bernardino Mountain segments, we also find a significant decrease in slip rate along the San Andreas in comparison with the geologic rates, in contrast to a significant increase in slip rate on faults along the eastern California shear zone. Along the southern San Andreas, slip rates vary from 21 to 25 mm/yr from the Coachella Valley to Imperial Valley segments. Slip rates range from 0 to 3 mm/yr across the western Transverse Ranges faults, which is consistent with the regional crustal thickening. Overall slip rates derived from geodetic observations correlate strongly with the geologic slip rates statistically, suggesting high compatibility between geodetic and geologic observations.

Prevention and treatment of osteoporosis rely on understanding of the micromechanical behaviour of bone and its influence on fracture toughness and cell-mediated adaptation processes. Postyield properties may be assessed by nonlinear finite element simulations of nanoindentation using elastoplastic and damage models. This computational study aims at determining the influence of yield surface shape and damage on the depth-dependent response of bone to nanoindentation using spherical and conical tips. Yield surface shape and damage were shown to have a major impact on the indentation curves. Their influence on indentation modulus, hardness, their ratio as well as the elastic-to-total work ratio is well described by multilinear regressions for both tip shapes. For conical tips, indentation depth was not statistically significant (p0.0001). For spherical tips, damage was not a significant parameter (p0.0001). The gained knowledge can be used for developing an inverse method for identification of postelastic properties of bone from nanoindentation.

The indentation-induced elastic-plastic zone in an IN 740 Ni-based superalloy was studied by three-dimensional (3-D) x-ray microdiffraction and electron back scattering diffraction (EBSD). Large lattice reorientations and the formation of geometrically necessary dislocations are observed in the area with a radius of ∼75 μm. A residual compression zone is found close to the indent edge. An elastic-plastic transition is observed at ∼20 μm from the indent edge. Depth dependent dislocation densities are determined at different distances from the indent edge.

In recent studies other investigatiors have presented traces of "light scattering" versus depth into the cornea. The present investigation demonstrates that these traces do not measure the actual light scatter intensity and that a proper interpretation of such traces shows that most of the scattering is from within the stroma.

Background Growth pattern in the electroencephalographic bicoherence spectrum has recently been found to relate to anesthetic depth, and bicoherence analysis can reflect behavior of the thalamocortical reverberating network. Because the thalamocortical network is known to represent a key factor in sleep by anesthesia, systematic and qualitative bicoherence studies of different anesthetic depths is necessary throughout all pairs of frequencies. Methods Sixteen patients were anesthetized using sevoflurane (1, 2, or 3%) combined with remifentanil (0.4 microg x kg x min). Raw electroencephalographic signals were collected, and bicoherence was estimated in all pairs of frequencies, between 0.5 and 40 Hz at 0.5-Hz intervals. Results Sevoflurane (1%) caused two main peaks, spindle frequencies (11.0 +/- 1.2 Hz, 44.7 +/- 12.3% [bicoherence growth]) and delta-theta frequencies (5.4 +/- 0.5 Hz, 33.0 +/- 8.4%), in the diagonal line of biphasic bicoherence plots. High concentrations of sevoflurane (2% and 3%) shifted these peaks to 9.8 +/- 1.1 Hz, 46.2 +/- 12.7%; 8.7 +/- 1.3 Hz, 37.2 +/- 13.7% and 4.9 +/- 0.5 Hz, 44.6 +/- 7.0%; 4.3 +/- 0.8 Hz, 45.2 +/- 10.6%, respectively. Sevoflurane caused a third bicoherence peak to appear in another heterogeneous pair frequency (pair of alpha basal frequency and its double frequency), outside the diagonal line, which also inherited the behavior of alpha bicoherence peaks at different anesthetic depths. Conclusions Sevoflurane anesthesia caused bicoherence peaks in alpha and delta-theta areas and also formed secondary third peaks. Deeper sevoflurane anesthesia shifted all bicoherence peaks to lower frequencies and caused increased bicoherence growth in the delta-theta area. The obtained features are consistent with characteristics of the thalamocortical reverberating network and suggest the importance of bicoherence analysis for the thalamic system.

A method is developed to describe the linear internal wavefield generated by an oscillating source in horizontally moving, depth-dependent background. Ray theory is used to approximate the vertical eigenfunctions. A spatial solution is then obtained by inverse Fourier transform. This is a practical approach with a more convenient range of validity than the method of spatial ray tracing. The solutions for a stationary source and for a vertically oscillating source in a vertically sheared background current are given for illustration.

Variations in blur are present in retinal images of scenes containing objects at multiple depth planes. Here we examine whether neural representations of image blur can be recalibrated as a function of depth. Participants were exposed to textured images whose blur changed with depth in a novel manner. For one group of participants, image blur increased as the images moved closer; for the other group, blur increased as the images moved away. A comparison of post-test versus pre-test performances on a blur-matching task at near and far test positions revealed that both groups of participants showed significant experience-dependent recalibration of the relationship between depth and blur. These results demonstrate that blur adaptation is conditioned by 3D viewing contexts.

The scaling properties of granular flows down an inclined plane are investigated in a model previously proposed to describe surface flows on a sandpile. Introducing a depth dependent friction, we are able to reproduce the results obtained experimentally by Pouliquen [Phys. Fluids 11, 542 (1999); 11, 1956 (1999)] on both the fronts velocities and their shapes.

The depth dependent track etch rates of two types of CR-39, TASTRAK and BARYOTRAK, for Li-7 ions with incident energies of 4.82, 6.75 and 10.77 MeV have been evaluated from track length measurements. The pit lengths versus the etching time obtained by three different laboratories have the same trend, but did not agree completely. The differences can be attributed to an error margin of less than one decimal point in the etching temperature. Significant deviations were also present for the assessed track etch rates. Most of the deviation was attributed to the derivation step of the growth curves. A sufficient amount of data and reasonably smooth growth curves were required near the Bragg peak in order to make a precise estimation.

Ground water production wells commonly are designed to maximize well yield and, therefore, may be screened over several water-bearing zones. These water-bearing zones usually are identified, and their hydrogeologic characteristics and water quality are inferred, on the basis of indirect data such as geologic and geophysical logs. Production well designs based on these data may result in wells that are drilled deeper than necessary and are screened through zones having low permeability or poor-quality ground water. In this study, we examined the application of flowmeter logging and depth-dependent water quality samples for the improved design of production wells in a complex hydrogeologic setting. As a demonstration of these techniques, a flowmeter log and depth-dependent water quality data were collected from a long-screened production well within a multilayered coastal aquifer system in the Santa Clara-Calleguas Basin, Ventura County, California. Results showed that the well yields most of its water from four zones that constitute 58% of the screened interval. The importance of these zones to well yield was not readily discernible from indirect geologic or geophysical data. The flowmeter logs and downhole water quality data also show that small quantities of poor-quality water could degrade the overall quality of water from the well. The data obtained from one well can be applied to other proposed wells in the same hydrologic basin. The application of flowmeter and depth-dependent water quality data to well design can reduce installation costs and improve the quantity and quality of water produced from wells in complex multiple-aquifer systems.

We investigate CZTSe films by polarization dependent Raman spectroscopy. The main peaks at 170 cm(-1), and 195 cm(-1) are found to have A symmetry. The Raman signal at 170 cm(-1) is found to be composed of two modes at 168 cm(-1) and 172 cm(-1). We attribute these three Raman peaks to the three A symmetry modes predicted for kesterite ordered Cu(2)ZnSnSe(4). The main Raman peak is asymmetrically broadened towards lower energies. Possible sources of the broadening are tested through temperature and depth dependent measurements. The broadening is attributed to phonon confinement effects related to the presence of lattice defects.

One of the most well studied issues in genetic programming is how to make building blocks efficiently. To make building blocks, it is important to find the substructures that appear in the individuals with higher fitness. Recently, a method based on frequent substructures has been proposed, and it has shown good performance; however, the depth of trees is not considered in the method. In this paper, we propose a hybrid crossover that involves the consideration of a combination of frequent trees and the depth of trees and apply the proposed method to symbolic regression problems. We experimentally demonstrate the effectiveness of the proposed method.

For many years, pharmaceutical therapies for osteoarthritis (OA) have been focused on the degenerating cartilage. However, there is increasing evidence that bone plays an important role in OA as well. The structural and material properties of the subchondral bone are modified, and bone cysts and osteophytes may develop. The mechanisms behind these bone changes are subject of debate, and a better understanding may help in the development of bone-targeting OA therapies.Copyright © 2011 by ASME

Time series analysis of ultrasound radio-frequency (RF) signals has been shown to be an effective tissue classification method. Previous studies of this method for tissue differentiation at high and clinical-frequencies have been reported. In this paper, analysis of RF time series is extended to improve tissue classification at the clinical frequencies by including novel features extracted from the time series spectrum. The primary feature examined is the Mean Central Frequency (MCF) computed for regions of interest (ROIs) in the tissue extending along the axial axis of the transducer. In addition, the intercept and slope of a line fitted to the MCF-values of the RF time series as a function of depth have been included. To evaluate the accuracy of the new features, an in vitro animal study is performed using three tissue types: bovine muscle, bovine liver, and chicken breast, where perfect two-way classification is achieved. The results show statistically significant improvements over the classification accuracies with previously reported features. Copyright 2011 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited

Monkeys can detect electrical stimulation delivered to striate cortex (area V1). We examined whether such stimulation is layer dependent. While remaining fixated on a spot of light, a rhesus monkey was required to detect a 100 ms train of electrical stimulation delivered to a site within area V1. A monkey signaled the delivery of stimulation by depressing a lever after which he was rewarded with a drop of apple juice. Control trials were interleaved during which time no stimulation was delivered and the monkey was rewarded for not depressing the lever. Biphasic pulses were delivered at 200 Hz and the current was typically at or less than 30 μA using 0.2 ms cathode-first biphasic pulses. For some experiments, the pulse duration was varied from 0.05 to 0.7 ms and anode-first pulses were used. The current threshold for detecting cathode-first pulses 50% of the time was the lowest (< 10 μA) when stimulation was delivered to the deepest layers of V1 (between 1.0 and 2.5 mm below the cortical surface). Also the shortest chronaxies (< 0.2 ms) and the shortest latencies (< 200 ms) for detecting the stimulation were observed at these depths. Finally, anode-first pulses were most effective at evoking a detection response in superficial V1 and cathode-first pulses were most effective at evoking a detection response in deep V1 (> 1.75 mm below the cortical surface). Accordingly, the deepest layers of V1 are the most sensitive for the induction of a detection response to electrical stimulation in monkeys.

Experience with road fills in Washington State constructed with thick layers of tire chips spontaneously burning has led to a decrease in tire chip use nationally. The field measurements and samples taken indicate that a pyrolitic reaction occurred at two roadfill sites in Washington State based on a comparison to know pyrolytic reactions in controlled settings. Pyrolysis in roadbeds containing tire chips is a new phenomena previously only found in open piles of processed tire chips. Because water and nutrients were introduced, iron oxidation, microbial digestion, and chemical oxidation are possible factors contributing to the pyrolytic reactions at the two Washington State sites. A new heat ignition theory from Japanese experiments suggests a theoretical answer to practical design depth limits in roadbeds and tire chip piles may be climate (air temperature) and depth dependent.

In contrast to manufacturing and assembly systems, disassembly systems are marked by non-deterministic work sequences. The control of disassembly systems which adequately reacts to stochastically induced plan deviations are, therefore, of great importance for an efficient operation of disassembly systems. Thus, special control procedures, aligned to the requirements of disassembly, are required in order to manage disassembly systems appropriately. In order to improve disassembly control strategies, a simulation-aided control procedure for systems based on division of labour is under development to support the following tasks: Planning of the sequence of the disassembly orders, variation of the disassembly depth dependent upon the capacity utilization and variation of the disassembly operations according to the capacity utilization.

PURPOSETo determine the cohesive tensile strength throughout the stroma of normal human donor corneas and evaluate the relevance of these findings within the context of current excimer laser surgical techniques. METHODSTwenty normal corneoscleral buttons from 11 donors were obtained from the Georgia Eye Bank. The corneas were cut into 3-mm strips, dissected at varying stromal depths, mechanically separated through the dissection plane using a motorized extensometer, and measured for cohesive tensile strength. Central corneal thickness and dissection depth were measured by routine light microscopy and correlated with cohesive tensile strength measurements. RESULTSA strong negative correlation was noted between stromal depth and cohesive tensile strength (r=–0.93). The anterior corneal stroma directly adjacent to Bowman’s layer followed by the underlying anterior 40% of the corneal stroma had the highest cohesive tensile strength. Cohesive tensile strength plateaued from 40% to 90% corneal stromal depth and then declined rapidly from the posterior 10% of the stroma to Descemet’s membrane. The anterior 40% of the corneal stroma had significantly higher cohesive tensile strength than the posterior 60% (33.3 g/mm vs 19.6 g/mm, P. CONCLUSIONSThe anterior 40% of the central corneal stroma is the strongest region of the cornea, whereas the posterior 60% of the stroma is at least 50% weaker. The risk for ectasia may therefore be greater with ablations into the posterior stroma. Increasing age is associated with increased corneal cohesive tensile strength. [J Refract Surg. 2008;24:S85-S89.] ABOUT THE AUTHORS From Emory University, Department of Ophthalmology (Randleman, Dawson, Grossniklaus, McCarey, Edelhauser) and Emory Vision (Randleman), Atlanta, Ga. Supported in part by Research to Prevent Blindness Inc, New York, NY; NEI grants EY-00933, P30-EY06360, T32-EY07092, Bethesda, Md; and the ASCRS Foundation’s Research Grant Program. The authors have no financial interest in the materials presented herein. Presented at the Sixth International Congress on Advanced Surface Ablation & SBK; May 5, 2007; Ft Lauderdale, Fla. Correspondence: J. Bradley Randleman, MD, 1365 B Clifton Rd NE, Ste 4500, Atlanta, GA 30322. E-mail: Jrandle@emory.edu

This chapter introduces ultrasonic characterization of dynamic depth-dependent biomechanical properties of articular cartilage. The ultrasound-swelling and ultrasound-elastomicroscopy systems are used, which show potentials for the investigation of the transient deformations of articular cartilage at different depths under dynamic loading. Ultrasound approaches inherently provide non-destructive assessment of articular cartilage. With the miniaturization of the ultrasound probes, these ultrasound techniques can be potentially used together with arthroscopes for in vivo assessment of articular cartilage. Studies suggest that these ultrasound approaches can also be potentially applied for dynamic mechanical assessment of other biological tissues, tissue engineered tissues, biomaterials and non-biomaterials.

The transcutaneous fluorescent imaging (TFI) method was applied to the imaging of a small experimental animal such as a rat. The feasibility of the functional imaging in TFI was verified. To make this method more practical, a technique of scattering suppression was proposed. The depth-dependent PSF was derived as an analytical solution in a closed form. The applicability of this technique to the functional TFI and its usefulness were demonstrated in animal experiments.