Transitional Segment Research Articles

Biomechanical Effects of Disc Degeneration and Hybrid Fixation on the Transition and Adjacent Lumbar Segments

The biomechanical effects of disc degeneration and hybrid fixation on the transition and adjacent segments were evaluated using a numerical approach. This study aimed to evaluate the rigidity-rising effects of the dehydrated disc and bridged fixator on the kinematic and mechanical redistribution of the transition and adjacent segments. After static fixation, a dynamic fixator can be used to preserve motion and share loads for the transition segments. However, the hybrid use of both static and dynamic fixators and its effects on the biomechanical behavior of the transition and adjacent segments were not investigated extensively. A nonlinear and osseoligamentous lumbar model from L1 vertebra to S1 vertebrae was developed. Ligament interconnection, muscular contraction, and weight compression were all used to simulate lumbar flexion. The static fixator was instrumented at the degenerative L4-L5 segment and the dynamic fixators (Dynesys system) with different stiffness were subsequently applied to the degenerative or healthy L3-L4 segment. A healthy lumbar model was used as a reference point for further comparison and evaluation. The predicted results were validated with the cadaveric and numerical values of the literature studies. Among the 21 models, the junctional problem at the adjacent (L2/L3 and L5/S1) discs as well as the motion preservation and stress distribution at the transition (L3/L4) disc were compared. Static fixation and the degenerative disc deteriorated the junctional problem at adjacent segments. On average, the hybrid fixation of the original Dynesys cord constrained the range of motion (ROM) by 65%. Furthermore, it shared 43% of the stress on the transition disc. However, this resulted in the adjacent discs increasing about 50% ROM and 40% stress. The term "trade-off stiffness" was used to express the concept that the decreased stiffness of the original cord could balance the junctional problem, motion preservation, and load protection of the transition and adjacent segments. The trade-off stiffness of the degenerative transition disc was higher than that of the healthy disc. Compared with the original design, the increased ROM and stress of the adjacent segments can be reduced by about 43% using the trade-off stiffness. The use of the hybrid fixator should involve a certain trade-off between the protection of the transition segment and the deterioration of the adjacent segments. This trade-off stiffness, which largely depends on both fixator design and disc degeneration, provides the improved rigidity and flexibility of the transition and adjacent segments.

Morphological features of the Amur sleeper (Perccottus glenii, Perciformes, Eleotridae) introduced into water bodies of European Russia

Data on eight morphological features of 29 Amur sleeper populations in water bodies of the acquired range of European Russia (50.0°–62.2°N) are presented and compared with 4 populations of the native range (43.5–48.2°N). It has been found that the formation of a certain number of vertebrae in the abdominal, transitional, and caudal segments of the axial skeleton in population groups recognized in the study is related to similar temperature conditions in the water bodies.

Mitigation of noise emissions from vehicles passing bridge expansion joints

In the German project �silent road traffic 2� a special sub-project for bridge expansion joint noise mitigation was launched. Travelling over a standard modular bridge expansion joint (lamella joint) with a vehicle creates a short noise impulse. The noise is the result of the vehicle�s tyres striking the rectangular face of the expansion joint units and traversing the discontinuous surface profile. This noise can be annoying for those residing near the bridge. A reduction of the noise emission can be achieved by mounting noise reduction elements on top of the transition segments, by creating an even surface for the tyre to traverse, and still allowing the joint to contract or elongate as required due to the influence of seasonal temperature variation. Different surface elements for covering the transition segments with varying shapes and surface textures were tested in the tyre-road-interaction test-facility (PFF) of BASt. The surface elements had different shapes and surface characteristics; five were of a rhomboidal shape with three profile angles, one was �mushroom� shaped, and two were of a sinusoidal shape. The surface elements were provided by two German manufacturers. The noises emission caused by traversing of a standard passenger car tyre was investigated for different velocities. All tests were carried out with two different spacings representing summer and winter position. It was found that a noise reduction of up to 9 dB could be achieved, when compared to conventional surface elements

Exploration on the Widening Value Calculation Method of Continuous Bends in Inland River

The widening value formulas of continuous bends currently in use cannot meet the requirements of the practical engineering because the values of them are far less than the realistic situation needs. Based on the method of combing the generalized open channel flow model of continuous bends with the experiment of small-sized ship model, and in accordance with the experimental data and the precursors’ experience, two of the channel widening value empirical formulas are obtained, which can respectively used in the upper bend and the lower bend of the continuous bends according to the length of the transitional linear segment sufficient or not.

Lumbosacral Transitional Vertebrae in Low Back Pain Population

Abstract Background: The relationship between lumbosacral transitional vertebrae and low back pain is not clear. This controversy has been quite intriguing and has been the stimulus for carrying out this present study. The aim of this study was to determine, by plain radiography, if there is a relationship between lumbosacral transitional vertebrae and low back pain. Material and methods: Five hundred lumbosacral radiographs of low back pain patients were examined. Dysplastic transverse process was classified according to the Castellvi radiographic classification system. The incidence of lumbosacral transitional vertebra in patients with low back pain was reported, and the patients who had anomaly were compared according to gender and age. Results: Of these patients, 118 were classified as positive for transitional lumbosacral vertebra, resulted in an incidence of 23.6%. The most common anatomical variant was Castellvi Type IA (6.8%). No statistically significant difference was found between these two age groups according to incidence of lumbosacral transitional vertebra (p=0.207). There were no statistically significant differences between men and women who had anomaly (p=0.289). Higher incidences of Type IB and Type IIB were found in men, but those results were not statistically significant (p=0.112, p=0.514) when compared with the female group. Conclusion: Based on our data, we conclude that lumbosacral transitional segments are common in the low back pain population. But no relationship found between age and genders.

Preliminary analysis of the sacroiliac joint in the hyperlordotic spine, a finite element model

Preliminary analysis of the sacroiliac joint in the hyperlordotic spine, a finite element model

Rectangular to Circular Waveguide Converter for Microwave Devices Characterization

In this paper, a rectangular to circular waveguide converter is investigated numerically and characterized experimentally for microwave devices characterization. The converter is designed as an excitation method of circular waveguide to produce its dominant mode as the problem of circular waveguide in the excitation process. A WR248 type rectangular waveguide transducer with working frequency of 2.60–3.95GHz for TE10 mode is used as the wave exciter to be converted to a WC248 type circular waveguide. Prior to the fabrication, physical parameters of converter including length of rectangular segment, length of transition segment and length of circular segment are analyzed to obtain the optimum design. It shows that the length of transition segment affects to the return loss of converter and its length to produce TE11 mode of circular waveguide smoothly has to be more than twice of waveguide wavelength. From the result, the length of transition segment is chosen to be 275mm as it demonstrates better return loss compared to other lengths almost in the designated working frequency. To verify the design result, the prototype of converter is then realized and characterized experimentally. Furthermore, some discussion related to the results of experimental characterization is also presented.

Dynamic response of masonry minarets strengthened with Fiber Reinforced Polymer (FRP) composites

Abstract. Engineering structures strengthened with FRP composites are gaining popularity, and there is a growing need to understand and compare the behavior of these structures before/after FRP composite strengthening. In this paper, it is aimed to determine the dynamic response of masonry minarets before/after FRP composite strengthening. An Iskenderpaşa historical masonry minaret dating back to XVI century with a height of 21 m located in Trabzon, Turkey was selected as an application. Firstly, 3-D finite element model of the minaret was constituted using ANSYS software. Then, an analytical model of the minaret was analyzed using the 1992 Erzincan earthquake record, which occurred near the area, to determine the dynamic behavior. After this, the cylindrical body of the minaret was strengthened with FRP composite using different configurations and dynamic analyses were performed. Finally, dynamic responses of the minaret before and after FRP composite strengthening, such as displacements and maximum-minimum principal stresses, were compared. At the end of the study, it is seen that displacements had increased along the height of the minaret, maximum and minimum principal stresses occur at the region of transition segment and cylindrical body for all analyses. Also, it is seen from the earthquake analyses that FRP strengthening is very effective on the dynamic responses of the minaret.

Neural Coding of Syntactic Structure in Learned Vocalizations in the Songbird

Although vocal signals including human languages are composed of a finite number of acoustic elements, complex and diverse vocal patterns can be created from combinations of these elements, linked together by syntactic rules. To enable such syntactic vocal behaviors, neural systems must extract the sequence patterns from auditory information and establish syntactic rules to generate motor commands for vocal organs. However, the neural basis of syntactic processing of learned vocal signals remains largely unknown. Here we report that the basal ganglia projecting premotor neurons (HVC(X) neurons) in Bengalese finches represent syntactic rules that generate variable song sequences. When vocalizing an alternative transition segment between song elements called syllables, sparse burst spikes of HVC(X) neurons code the identity of a specific syllable type or a specific transition direction among the alternative trajectories. When vocalizing a variable repetition sequence of the same syllable, HVC(X) neurons not only signal the initiation and termination of the repetition sequence but also indicate the progress and state-of-completeness of the repetition. These different types of syntactic information are frequently integrated within the activity of single HVC(X) neurons, suggesting that syntactic attributes of the individual neurons are not programmed as a basic cellular subtype in advance but acquired in the course of vocal learning and maturation. Furthermore, some auditory-vocal mirroring type HVC(X) neurons display transition selectivity in the auditory phase, much as they do in the vocal phase, suggesting that these songbirds may extract syntactic rules from auditory experience and apply them to form their own vocal behaviors.

Investigation of blade performance of horizontal axis wind turbine based on blade element momentum theory (BEMT) using NACA airfoils

The basic principle of wind turbine converting wind energy into electricity comes from the lift produced by the air flowing through the rotor. The shape of rotor blade plays an important role in determining the overall aerodynamic performance of a horizontal axis wind turbine. In this work, blade is designed for a 5KW horizontal axis wind turbine which is already in market. For designing blade, blade element momentum theory (BEMT) is used and a computer program is developed to automate the complete procedure. Two NACA airfoils are taken for the comparative calculation of elemental power coefficient and other parameters such as chord, thickness and twist distribution. The airfoil taken for designing the blade is same from root to tip. Stresses are maximum at the blade root. In this work, the blade root is thickest portion of the blade and twist is maintained such that the angle of attack will be maximum at every station of the blade. In the designed blade, the elemental power coefficient is maximum in transition segment. The present method is useful for predicting the performance of wind turbine blade.

Study on headland-bay sandy coast stability in South China coasts

Headland-bay beach equilibrium planform has been a crucial problem abroad to long-term sandy beach evolution and stabilization, extensively applied to forecast long-term coastal erosion evolvement and the influences of coastal engineering as well as long-term coastal management and protection. However, little concern focuses on this in China. The parabolic relationship is the most widely used empirical relationship for determining the static equilibrium shape of headland-bay beaches. This paper utilizes the relation to predict and classify 31 headland-bay beaches and concludes that these bays cannot achieve the ultimate static equilibrium planform in South China. The empirical bay equation can morphologically estimate beach stabilization state, but it is just a referential predictable means and is difficult to evaluate headland-bay shoreline movements in years and decades. By using Digital Shoreline Analysis System suggested by USGS, the rates of shoreline recession and accretion of these different headland-bay beaches are quantitatively calculated from 1990 to 2000. The conclusions of this paper include that (a) most of these 31 bays maintain relatively stable and the rates of erosion and accretion are relatively large with the impact of man-made constructions on estuarine within these bays from 1990 to 2000; (b) two bays, Haimen Bay and Hailingshan Bay, originally in the quasi-static equilibrium planform determined by the parabolic bay shape equation, have been unstable by the influence of coastal engineering; and (c) these 31 bays have different recession and accretion characters occurring in some bays and some segments. On the one hand, some bays totally exhibit accretion, but some bays show erosion on the whole. Shanwei Bay, Houmen Bay, Pinghai Bay and Yazhou Bay have the similar planforms, characterized by less accretion on the sheltering segment and bigger accretion on the transitional and tangential segments. On the other hand, different segments of some bays have two dissimilar evolvement characters. Dacheng Bay, Shenquan Bay, Hudong Bay, Wukan Bay, Fengjia Bay, Wuchang Bay, Lingshui Bay and Tufu Bay produce accretion on the tangential segment, erosion on the transitional segment and accretion on the sheltering segment. However, Guang’ao Bay, Haimen Bay, Jinghai Bay, Sanya Bay(a), Dajiao Bay, Hailingshan Bay, Hebei Bay, Fuhu Bay, Shuidong Bay, Wangcun Bay and Bomao Bay generate erosion on the tangential part, accretion on the transitional part and accretion on the sheltering part. It seems to imply some relations between headland-bay beach evolvement and controls on headland-bay beaches, which may possibly to classify headland-bay beach types and should be further studied.

Ausência de arteriosclerose na porção intramiocárdica das artérias coronárias

Several studies show that portions of intramyocardial coronary arteries are spared of arteriosclerosis, involving morphological, embryological, biochemical and pathophysiological aspects. Endothelial function is significantly affected in the segment of transition, as estimated by the vasoactive response to Ach. These findings suggest that myocardial bridge can provide protection against arteriosclerosis by counteracting the negative effects of endothelial dysfunction. The intramyocardial portion's protection phenomenon deserves further scientific research on all research fronts. Improved morphological, biomechanical and especially physiological and embryological knowledge may be the key to a future window of opportunity for chronic arterial disease therapy and prevention. In addition, this review discusses possible therapeutic approaches for symptomatic coronary ischemia caused by myocardial bridges.

A versatile approach to achieve quintuple-shape memory effect by semi-interpenetrating polymer networks containing broadened glass transition and crystalline segments

Multiple-shape memory effects (SME) from dual to quintuple are realized in PMMA/PEG semi-interpenetrating polymer networks containing broadened glass transition and crystalline segments, which provide multi-gradient glass transition temperatures and an additional melting temperature as transition temperatures for multi-step shape fixation and recovery in a single shape memory cycle. Especially, the quintuple-SME is achieved in polymeric material for the first time.

Transitional lumbosacral segment with unilateral transverse process anomaly (Castellvi type 2A) resulting in extraforaminal impingement of the spinal nerve

The spinal nerve can be pinched between the transverse process of the fifth lumbar vertebra and the sacral ala. The patients are divided into two types: elderly persons with degenerative scoliosis and somewhat younger adults with isthmic spondylolisthesis. For the first time, we describe extraforaminal impingement of the spinal nerve in transitional lumbosacral segment with unilateral transverse process anomaly. Selective nerve root blocks were performed in two clinical cases. One patient underwent nerve root decompression via a posterior approach. One year after operation, this patient reported no radicular or lumbar pain. The pathoanatomical study demonstrated pseudoarthrosis between the transverse process and the ala of the sacrum and showed dysplastic facet joints at the level below the transitional vertebra in all specimens. Furthermore, we present the oldest illustration of this pathological condition, published in a book by Carl Wenzel in 1824. Extraforaminal entrapment of the spinal nerve in transitional lumbosacral segment with unilateral transverse process anomaly can cause radiculopathy, and osteophytes are the cause of the entrapment. Dysplastic facet joints on the level below the transitional vertebra could be one reason for "micromotion" resulting in pseudoarthrosis with osteophytes. Sciatica relief was obtained by means of selective nerve root blocks or posterior decompression via a dorsomedial approach.

Seismic Response of a Historical Masonry Minaret using a Finite Element Model Updated with Operational Modal Testing

This paper presents the earthquake response of a historical masonry minaret after a finite element model updating was undertaken using the information from full scale ambient vibration testing. The Iskenderpaşa historical masonry minaret dating back to the 16th century with a height of 21m located in the city center of Trabzon, Turkey is selected as an application. Analytical modal analysis is performed on the 3D finite element model of the minaret considering field survey and engineering judgments to obtain the analytical frequencies and mode shapes. The field ambient vibration tests on the minaret under natural excitations such as wind loading and human movement are conducted. The Peak Picking and the Stochastic Subspace Identification techniques are used to extract the modal parameters from the ambient vibration test. A good correlation was found among the modal parameters identified from the two techniques. The finite element model of the minaret is updated to minimize the differences between analytically and experimentally estimated modal properties by changing some uncertain modeling parameters such as material properties and boundary conditions. The analytical model of the minaret after finite element model updating is analyzed using the 1992 Erzincan earthquake record, which occurred near the area, to determine the earthquake behavior of the minaret. At the end of the study, maximum differences in the natural frequencies are reduced on average from 27% to 5% and a good agreement is found between analytical and experimental natural frequencies and mode shapes by model updating. Also, it is seen from the earthquake analysis that the displacements increase along the height of the minaret and the maximum and minimum principal stresses occur at the region of the transition segment and the cylindrical body.

Applications of CFD Technique in the Design and Flow Analysis of Implantable Axial Flow Blood Pump

Based on established numerical methods and hydrodynamic performance testing facilities, CFD technique are applied to improve the design of the implantable axial flow blood pump and the flow analysis. (1) Applying brushless machine magnet steel, reducing its thickness while increasing the length, the flow channel's cross-section is increased, with no space connection between the large and the small rotators, and with a cone transition segment from the bearing to the principal axis, the flow is made smoother. The rotating speed is lowered by 1000 rpm – 1200 rpm under the same flow rate and pressure head, and thus the hemolysis can be avoided. (2) Different outlet stator guiding vanes are selected for the same blood pump for analyses of hydrodynamic performances and flow fields. An excellent design not only can regulate the rotating flow field into an axial one, reduce the circulation loss and improve the pump efficiency, but also can avoid backflow, vortex and secondary flow at the pump outlet, and thus the thrombus can be prevented. (3) The calf live tests show that some residual clots exist at the inner wall of the outlet connection bends, which are analyzed and explained by CFD techniques and the corresponding improvements are proposed. All results are verified by hydrodynamic performance tests and PIV flow field tests, and consistent conclusions are obtained.

A three-segment anisomorphic constant life diagram for the fatigue of symmetric angle-ply carbon/epoxy laminates at room temperature

The anisomorphic constant fatigue life (CFL) diagram approach that was developed in an earlier study is further tested for applicability to the matrix-dominated fatigue failure in symmetric angle-ply carbon/epoxy laminates. An extension of the CFL diagram approach is also attempted to improve the accuracy of fatigue life prediction. The original anisomorphic CFL diagram approach can be used for approximately predicting the CFL diagrams for the [±30] 3S and [±45] 3S laminates, while it fails to accurately predict the CFL diagram for the [±60] 3S laminate due to its significant local distortion. For accommodating the anisomorphic CFL diagram approach to the local distortion in CFL curves due to a significant change in mean stress sensitivity in fatigue, a transitional segment is inserted between the tension–tension and compression–compression dominated segments. It is demonstrated that the three-segment anisomorphic CFL diagram approach allows improved predictions of the CFL diagrams and S– N relationships for the angle-ply laminates.

Speed Factors on Low-Volume Roads for Horizontal Curves and Tangents

Many studies on driver speed behavior are found in the scientific literature today, and various researchers have addressed roadway alignment consistency for travel safety in context with current operating speeds. Experimental analysis was conducted on low-volume roads in Southern Italy without spiral transition curves between geometric tangent and circular elements on the horizontal alignment. All selected roads are located in areas with level terrain and vertical grades less than 6%. This study will illustrate a methodology, widely employed in the literature, to evaluate at each circular curve transition segment length, the applicable deceleration and acceleration rates. These results were then used to develop four equations for speed prediction models on tangents and curves. These regression equations were developed using a traditional Ordinary-least-squares method involving speed values not surveyed in transition zones. The goal of this research study is to plot continuous speed profiles to illustrate complete driver speed behavior on twolane rural roads and to individualize critical roadway sections to improve driver safety.

Temperature Zonal Combustion Reactor for the 15-Nitrogen and 13-Carbon Isotopic Determination of Enriched Biosynthetic Materials

A temperature distribution was imposed on a solid−gas reactor to help accomplish the 15-nitrogen or 13-carbon isotopic determination of biosynthetic materials such as algal protein-15N. The temperature zonal combustion reactor (TZCR) can operate offline from its mass spectrometer, and this reactor facilitates the stable isotopic determination of highly enriched biomaterials (>95 atom % isotope). The reactor structure is a glass pipe comprising a quartz segment, transition segments, and threaded sockets. Precise positioning of the reactor within a tubular furnace establishes a longitudinal temperature distribution that is used to drive solid−gas chemistry in distinct zones: sample, catalyst, and sorbent. The TZCR module typically includes a reactor pipe, gastight valve, sample, reactants, reactant containers, and furnace. An important advantage of TZCR-mass spectrometer is preliminary vacuum heat treatment of the crude sample to remove volatile impurities before sample combustion (enabling isotopic enrichment determination of the analyte). For the determination of 15N enrichment, sample combustion at 650 °C in oxygen was supplemented by Fe3O4 catalyst near 500 °C and Li2O at 25 °C that concertedly promoted the intrareactor depletion of CO, CO2, and H2O. As a result, the primary gaseous product was dinitrogen. After 15N sample conversion, the reactor was coupled to a quadrupole MS for product analysis (N2+ ions for 15N determination). Accordingly, uniformly enriched biomaterials were analyzed such as algal protein-15N that measured 99.0 ± 0.12 atom % 15N. By adapting the methodology for 13C determination, lyophilized algal cells-13C were determined to be 99.1 ± 0.06 atom % 13C. Stable isotope enrichments were computed by minimizing the numeric differences between theoretical and actual MS signals.

Living spontaneous gradient copolymers of acrylic acid and styrene: one-pot synthesis of pH-responsive amphiphiles

RAFT polymerization was used to prepare copolymers of acrylic acid (AA) and styrene (STY) with mole fractions of STY (FSTY) ranging from 0.1 to 0.3 and targeted degrees of polymerization between 50 and 150. The high reactivity of AA-terminal radicals towards STY in this system (rAA = 0.082) resulted in the spontaneous formation of composition gradients, resulting in polymers with block-like structures comprising a STY-rich segment, a relatively short transitional segment, and a segment of AA homopolymer. Atomic force microscopy analysis of thin films of the copolymer revealed phase separated structures which developed after exposure to water. Dynamic light scattering measurements showed pH-responsive amphiphilicity that resulted in dissolved polymer at neutral and basic pH and self-assembly in weakly acidic solutions.