Upper Corner Research Articles

Biomechanical rationale of sacral rounding deformity in pediatric spondylolisthesis: a clinical and biomechanical study

Rounding surface of the sacral dome and wedging deformity of the vertebral body are commonly observed in patients with isthmic spondylolisthesis. Recently, an animal study showed that the deformity can be caused by the growth plate involvement in the immature pediatric vertebral body after biomechanical alteration due to the pars defects. However, the pathomechanism and biomechanics of these deformities have yet to be clarified. To demonstrate that the sacral rounding deformity observed in pediatric patients with spondylolisthesis can be reversed, and to understand the pathomechanism of the deformity from the biomechanical standpoint by analyzing changes of stress around the growth plate of the vertebral body due to spondylolysis. Three-dimensional finite element pediatric lumbar models of the L3-L5 segment were utilized. Unlike the adult model, this pediatric model had growth plates and apophyseal rings. We analyzed stress distribution in response to 351°N axial compression and 10 N m moment in flexion, extension, lateral bending, and axial rotation. Bilateral spondylolysis was created in the model at the L4 level. The stress in the bilateral defect model was compared to the intact model predictions and the results obtained in the pediatric patients with sacral rounding deformity. Two patients presented rounding deformity of the anterior upper corner at S1 at the initial visit. They were asked to stop sports activities and use a soft trunk brace. Twelve months later, no rounding deformity was observed on the radiographs indicating that this deformity was reversible in pediatric cases. The biomechanical study indicated that in the pediatric spondylolytic spine, mechanical stress increased at the anterior upper corner during lumbar motion. In the presence of spondylolysis, mechanical stress increases in the growth plate at the anterior upper corner. Repetitive increases of mechanical stress may cause rounding deformity of the sacral dome mediated by growth plate involvement. When mechanical stress at the growth plate is reduced by wearing a brace, the proper functioning of the growth plate can help to remodel the sacral dome to its normal shape.

Preliminary Research on Porous Foam Ceramics Against Gas Explosions In Goaf

Gas explosion is one of the most serious accidents threatening the safety of the coal mines in China. The goaf, especially the upper corner, tends to accumulate methane and leak air, which constitutes a potential gas explosion source. Control of the methane in this area remains a concern among coal mine operators. In response to spontaneous combustion that leads to explosion, it is supposed that a porous medium, foam ceramics, be installed in the conjuncture between the working face and goaf according to the “Three Zones” of spontaneous combustion and high- temperature zone distribution in gob area. Theoretical analysis and experimental research demonstrate that, due to numerous collisions with walls, the foam ceramics can significantly destroy the free radicals generated from chemical reactions in gas combustion, inhibit the heat release, making the chemical reaction not self-sustained. Consequently, flame propagation is suppressed and shock wave attenuated. Given the advantages of foam ceramics of large porosity, high temperature resistance and powerful shock resistance, it is supposed that the foam ceramics be installed properly to isolate the gas explosions in the goaf. However, such installation needs further validation experimentally and on the site.

Bilaterality in the regular sea urchin Anthocidaris crassispina is related to efficient defense not to efficient locomotion

Regular sea urchins show pentaradial symmetry: they have round bodies made of five almost identical sectors. There is no preference in which sector should be anterior in their locomotion. Anthocidaris crassispina is exceptional among regular sea urchins. Morphometry showed that their tests had radial symmetry but the overall body shape showed bilateral symmetry because of the uneven distribution of spine length. This bilateral axis did not correspond to the ambulacrum III—interambulacrum 5 axis, which is the bilateral axis of irregular sea urchins. Their behavior in relation to this bilaterality was observed in the aquarium. At rest, most of them stayed in the upper corner of the aquarium keeping the sector with the shortest spine length (the shortest sector) toward the water surface. At walking, most of them moved on the vertical wall just under the water surface keeping the shortest sector directing to the water surface. When they walked in the open space, they moved in a random direction with respect to the bilaterality of the spines. The bilaterality and the behavior of this sea urchin were interpreted as the adaptation to defense not to efficient locomotion.

3D Micro-Crack Propagation Simulation at Enamel/Adhesive Interface Using FE Submodeling and Element Death Techniques

This study investigates micro-crack propagation at the enamel/adhesive interface using finite element (FE) submodeling and element death techniques. A three-dimensional (3D) FE macro-model of the enamel/adhesive/ceramic subjected to shear bond testing was generated and analyzed. A 3D micro-model with interfacial bonding structure was constructed at the upper enamel/adhesive interface where the stress concentration was found from the macro-model results. The morphology of this interfacial bonding structure (i.e., resin tag) was assigned based on resin tag geometry and enamel rod arrangement from a scanning electron microscopy micrograph. The boundary conditions for the micro-model were determined from the macro-model results. A custom iterative code combined with the element death technique was used to calculate the micro-crack propagation. Parallel experiments were performed to validate this FE simulation. The stress concentration within the adhesive occurred mainly at the upper corner near the enamel/adhesive interface and the resin tag base. A simulated fracture path was found at the resin tag base along the enamel/adhesive interface. A morphological observation of the fracture patterns obtained from in vitro testing corresponded with the simulation results. This study shows that the FE submodeling and element death techniques could be used to simulate the 3D micro-stress pattern and the crack propagation noted at the enamel/adhesive interface.

Proposal for a Didactic Aid to Practice the Bank Shots in Basketball

Abstract The aim of the paper was to propose a didactic aid to practice and develop bank shots in basketball. Four basketball players (three men and one 13-years old woman) were shooting bank shots from six distances (1, 2, 3, 4, 5 and 6 m) and at four angles (90 o , 75 o , 45 o and 25 ) respective to the board. An experimenter positioned behind the transparent backboard recorded the points of impact of 15 successful shots (without touching the rim) for each of the above distances, angles and shooters. With perpendicular shots at the backboard, we identified only negligible dislocation of the set of impact points. With angled shots, the set of impact points tended to move towards the side edge of the board and upwards depending on the angle of the shooter’s position to the board and his/her distance. The farther the shooter from the basket and the lower the angle at which the shooter was shooting, the closer the impact point was towards the upper corner of the board.We proposed a very simple and economically viable didactic aid to practice bank shots, consisting of a circle and two slanted ellipses placed on the backboard.

A Lateral Approach at the Upper Corner of Orbit in Fronto-Orbital Fibrous Dysplasia

A Lateral Approach at the Upper Corner of Orbit in Fronto-Orbital Fibrous Dysplasia

Analysis and key control technologies to prevent spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines

In order to prevent spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines in China, we have analyzed the characteristics of spontaneous coal combustion and explain theoretically the factors affecting spontaneous coal combustion, such as rock bursts, high temperatures, high ventilation resistance, slow advancing speed and large obliquity mining. Key technologies to prevent spontaneous combustion occurring in sharply inclined seams in deep mines are proposed; these include pouring water, stopping leakage in upper and lower corners of the working face, choking off the goaf and covering the coal. CO concentrations were controlled within two years to less than 15×10 −6 at the upper corner by applying these technologies at the 1410 working face of the Huafeng coal mine. Our method has significant theoretical value and is of practical importance in controlling spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines.

Damage accumulation simulations in the adhesive of enamel/ceramic interface using the FE submodelling and the element deactivation approaches.

PURPOSE To investigate the micromechanics and damage accumulation of the enamel/adhesive interface using sub-modelling and element deactivation methods. MATERIALS AND METHODS A finite element (FE) macromodel of the enamel/adhesive/ceramic interface subjected to shear bond testing was generated for mechanical analysis. The FE micromodel was constructed at the upper enamel/adhesive interface where stress concentration was found. The morphology of the micromechanical interlockings at the bonded interface was assigned based on a scanning electron micrograph. Boundary conditions of the micromodel were determined from the macromodel's results. Furthermore, an iterative code with the element deactivation method was used to calculate the microdamage accumulation. Parallel experiments were performed to validate the simulation. RESULTS The micromodel results demonstrated that stress concentration within the adhesive mainly occurred at the upper corner near the enamel/adhesive interface and the base of the resin tags. A simulated fracture path was found at the base of the resin tags along the enamel/adhesive interface. The morphological observation of fracture patterns obtained from in vitro testing corresponded with the simulation results. CONCLUSION This study showed that the FE submodelling and the element deactivation approaches could better simulate the micromechanical responses and the microdamage accumulation noted at the enamel/adhesive interface.

Modeling and validation of local acrylamide formation in a model food during frying

Acrylamide formation in a food model during frying can be analyzed in space and time with a traditional heat and mass transfer approach. In this paper a joint simulation/experiment approach has been exploited: the computational fluid dynamics has been coupled to chemical kinetics, to describe concentration and temperature fields in a food substrate, subject to interdependent and non-uniform heat and mass transfer, while validating measurements have been performed by high performance liquid chromatography. A multi-objective SIMPLEX optimization has been finally employed for the overall model tuning, incorporating all phenomenological variations. The numerical results confirmed that the acrylamide formation is non-linearly dependent on the operating thermal regime, in general more than doubling its average levels when the process temperature is increased by 10% only. Based on the proposed acrylamide maps, a maximum concentration locus is found on the product’s upper corner, depending on the specific transport ensemble and therefore on the local process conditions. For potato frying at an initial temperature of 190 °C, the maximum local acrylamide level after 4 min (almost 4 × 10 −2 mg/g) is almost four times the one obtained when frying at 170 °C, while scaling only linearly with process duration.

Direct numerical simulation of low Reynolds number flows in an open‐channel with sidewalls

AbstractA direct numerical simulation of low Reynolds number turbulent flows in an open‐channel with sidewalls is presented. Mean flow and turbulence structures are described and compared with both simulated and measured data available from the literature. The simulation results show that secondary flows are generated near the walls and free surface. In particular, at the upper corner of the channel, a small vortex called inner secondary flows is simulated. The results show that the inner secondary flows, counter‐rotating to outer secondary flows away from the sidewall, increase the shear velocity near the free surface. The secondary flows observed in turbulent open‐channel flows are related to the production of Reynolds shear stress. A quadrant analysis shows that sweeps and ejections are dominant in the regions where secondary flows rush in toward the wall and eject from the wall, respectively. A conditional quadrant analysis also reveals that the production of Reynolds shear stress and the secondary flow patterns are determined by the directional tendency of the dominant coherent structures. Copyright © 2009 John Wiley & Sons, Ltd.

Duck’s Not Afraid of the Dark! (review)

Reviewed by: Duck’s Not Afraid of the Dark! Elizabeth Bush Long, Ethan. Duck’s Not Afraid of the Dark! written and illus. by Ethan Long. LB Kids, 2009 [30p]. ISBN 978-0-316-01721-3 $10.99 Reviewed from galleys R 3–6 yrs We’ve already discovered that Duck is ticklish (Tickle the Duck! BCCB 2/06) and smoochy (Stop Kissing Me! BCCB 9/07), but now he admits an even darker—literally—secret: he can’t sleep without a light. You can bet that plenty of listeners share the problem, and Long puts them in charge of the light switch in this interactive offering featuring an actual flippable switch. Whenever Duck’s bedroom is fully illuminated, he’s ready to natter on about his bravery; well, his need for a nightlight; well, his terror of a monster under his bed (lift the flap to see it’s really a teddy bear). Whenever a page turn cues viewers to flip the switch in the upper corner with a “click!”, Duck’s left in the dark, prompting, of course, another ducky outburst. Duck’s oversized, loudmouth bill and anxious googly eyes should make even the most sleep-resistant kids feel fearless by comparison, and allowing them to assume the adult role of “lights out” commander is a pretty empowering strategy. One can only hope that their nighttime phobias die out before the battery does. Copyright © 2009 The Board of Trustees of the University of Illinois

Security in gas discharge while unsealing a closed stope

Given the problem of harmful gas discharge in unsealing coal mining faces, we numerically simulated the process of change of gas flows and movements. We have pointed out that, at the moment of unsealing a closed stope, the gas discharge is naturally divided into two parts, i.e., the discharge of gas in the working face and that in the goaf, because of the difference in the spatial medium. The absolute volume of gas discharged has a tendency to decrease from its initial peak value to a final stable value. The rate of decrease and the time needed to reach a stable discharge are related to the scale of the mining stope. The discharge of gas from the working face is closely related to the amount of air distributed in the air return way. The most important thing in unsealing a stope is to have the initial peak volume of gas discharged well under control. A commonly used method in solving this problem is at first to use a small amount of air and then increasing it gradually. Our study shows that, by extracting gas from the upper corner, we can use a large volume of air at first in order to shorten considerably the discharge time and improve efficiency, thereby making mining activity safer.

PINPOINT SOURCE LOCALIZATION FOR OCULAR NONSELECTIVE ATTENTION WITH COMBINATION OF ERP AND fNIRI MEASUREMENTS

Compared with event-related potential (ERP) which is widely used in psychology research, functional near-infrared imaging (fNIRI) is a new technique providing hemodynamic information related to brain activity, except for electrophysiological signals. Here, we use both these techniques to study ocular attention. We conducted a series of experiments with a classic paradigm of ocular nonselective attention, and monitored responses with fNIRI and ERP respectively. The results showed that fNIRI measured brain activations in the left prefrontal lobe, while ERPs showed activation in frontal lobe. More importantly, only with the combination measurements of fNIRI and ERP, we were then able to find the pinpoint source of ocular nonselective attention, which is in the left and upper corner in Brodmann area 10. These results demonstrated that fNIRI is a reliable technique in psychology, and the combination of fNIRI and ERP can be promising to reveal more information in the research of brain mechanism.

Influence of Parameters during Induction Heating Cycle of 7075 Aluminium Alloys with RAP Process

Thixoforging involves shaping alloys with a globular microstructure in the semi-solid state. To reach this kind of material, the Recrystallisation and Partial Melting (RAP) process can be used to obtain a globular microstructure from extruded material with liquid penetrating the recrystallised boundaries. Induction heating is used to apply the RAP process to slugs. One of the benefits of using this method of heating is the fast heating rate (20°C/s). This paper will help to improve heating parameters by showing their influence on 7075 aluminium alloy recrystallisation. These parameters are the heating rate; heating frequencies-power; presence or not of protective gas; position of the slug in the inductor; energy stored inside the slug; oxide layer on the slug side; chamfer of the slug upper corner.

Thermal Resistance Minimization of a Fin-and-Porous-Medium Heat Sink with Evolutionary Algorithms

This article presents a conceptual design of a heat sink combining a porous medium whose matrix is highly conductive and a fin. A simplified model is presented to estimate the performance of the system, relying on Darcy law and local thermal equilibrium. The objective is to minimize the hot-spot temperature under global mass constraint by using an optimization procedure based on genetic algorithms. The design variables are the porosity and material of each layer of the porous medium, the fin material, height, and width, the aspect ratio of the heat sink, and the shape of a weightless upper corner deflector which reduces the width of the inlet and outlet air slots while removing the less useful mass. Results show that the optimal porous layers were generally of copper, independent of the mass constraint. However, the fin is mostly beneficial for heavier designs, while the deflector becomes more important when lightness is required. These two special features show their efficiency by allowing a mass reduction of 95% with a decrease of only 24% in the cooling performance.

Abdominal Wall Endometriosis: An Overlooked but Possibly Preventable Complication

To find ways of preventing abdominal wall endometriosis through a retrospective case review. A retrospective study of 22 patients presenting with 26 postoperative abdominal wall masses. All masses were pathologically proved to be scar endometriosis between September 1994 and September 2006. The age, parity, symptoms and duration, previous surgeries, interval between previous surgery and current operation, initial diagnosis, and the 26 sites and size of endometrioma were recorded and analyzed. About 60% of the patients were in the fourth decade of life. All 22 cases, except one with mid-trimester hysterotomy, had previous cesarean section (CS). Three cases had vertical midline incision for CS, and the other 19 had Pfannenstiel incision, 18 of which were for CS and one for hysterotomy. Of the 22 cases, only three had multiple endometriomas, i.e. one case had three foci and the other two cases had two foci each. Twenty-three endometriomas were found in the Pfannenstiel incision group; 19 out of the 23 foci (82%) were located in either corner of the Pfannenstiel incision wounds (with right side predominance in 13 out of 19). Three endometriomas were noted in vertical midline incisions and two were in the upper corner. Three endometrioma excisions were done during repeated CS. Abdominal wall endometriosis may be caused by iatrogenic inoculation of the endometrium into the surgical wound. It is strongly recommended that, at the conclusion of the surgical procedure, the abdominal wound be cleaned thoroughly, particularly at both corner sites (especially the operators side). If an abdominal wall endometriosis is encountered after CS but the patient plans to have future pregnancy and the symptoms are mild, excision of the endometrioma may be deferred until the next indicated CS.

Improved matrix pair undecidability results

We improve the undecidability bounds for problems involving two integer matrices by showing that Scalar Reachability, Zero in the Right Upper Corner, Vector Reachability, and Zero in the Left Upper Corner are undecidable for dimensions of 9, 10, 11, and 13, respectively. Problems Scalar Reachability, Zero in the Right Upper Corner, and Vector Reachability were previously known undecidable for dimensions 18, 18, and 16, respectively.

Galvayne’s groove and the presence of a hook on the upper corner incisors are poor indicators of age in horse teeth

Galvayne's groove and the dental hook are two characteristic features of the upper corner incisors of horses. Both characteristics have traditionally been claimed to appear at specific ages and have therefore often been used for dental age determination. Recent studies, however, have questioned the accuracy of these criteria and concluded that the presence of a 7-year-hook is irrelevant for estimation of age in horses, whereas Galvayne's groove may be a useful adjunct after all other morphological criteria have been considered. The present paper intends to illustrate the variable appearance of both characteristics in the dentition of Standardbred, Arabian and Belgian draft horses and in mini-Sheflandponies (n = 490) ranging in age from 5 to 28 years old.

Algorithm 859

BABDCR is a package of Fortran 90 subroutines for the solution of linear systems with bordered almost block diagonal coefficient matrices. It is designed to handle matrices with blocks of the same size, that is, having a block upper bidiagonal structure with an additional block in the right upper corner. The algorithm implemented in the package performs cyclic reduction of the coefficient matrix in order to reduce the fill-in due to the corner block.

Development of a pultruded FRP composite material ROPS for farm tractors

The goal of this research was to explore the feasibility of fabricating a fixed-structure ROPS (rollover protective structure) for farm tractors from an FRP (fiberglass reinforced plastic) composite material. Evaluating the strength of proposed joint designs for the base and the upper corners of the FRP ROPS was the focus of this study. Three factors were investigated: base fixture strength for connecting the ROPS to the tractor, upper corner fastening strength, and FRP failure mechanisms under static loading. Results indicate the need for a well-bolted mounting connection. Also, the failure modes at bolted upper corners of an FRP ROPS were related to where bolt holes are located. Additionally, long cantilever beams similar to the vertical members of a ROPS absorbed energy well without significant lengthwise fiber failure. Failures observed were only at the base, rather than in the localized matrix failure that occurs at the loading point of shorter beams. When the full ROPS was loaded to failure, it exhibited three shear breakthroughs of matrix material at bolt holes before reaching its ultimate load strength at 53,370 N (12,000 lbf). An ultimate performance comparison to be evaluated is whether an FRP ROPS has equal or better impact energy absorption performance than a steel ROPS and whether it deflects no further than a steel ROPS element with an acceptable amount of deformation. Damage tolerance that takes into account changes in strength of an FRP ROPS due to tools and other objects striking it must be considered. With appropriate impact characteristics factored into a design, the value of FRP composites for ROPS is expected to reside in longevity and lower manufacturing costs.