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Sample records for fractured slab techniques

  1. Fracture of solid state laser slabs

    SciTech Connect

    Marion, J.E.

    1986-07-01

    Fracture due to thermal stress limits the power output potential of modern, high average power slab lasers. Here the criteria for slab fracture and the nature of the surface flaws which constitute the strength-controlling defects are reviewed. Specific fracture data for gadolinium scandium gallium garnet and LHG-5 phosphate glass with different surface finishes are evaluated in the context of assigning appropriate slab operating parameters using Wiebull statistics. These examples illustrate both the danger of design using brittle components without adequate fracture testing, and the inadequacy of design methods which use a fixed safety factor, for this class of materials. Further consideration reveals that operation of slab lasers in contact with an aqueous coolant may lead to strength degradation with time. Finally, the evolution of the failure process in which a characteristic midplane crack forms is outlined, and the pertinent parameters for avoiding slab fracture are identified.

  2. May eclogite dehydration cause slab fracturation ?

    NASA Astrophysics Data System (ADS)

    Loury, Chloé; Lanari, Pierre; Rolland, Yann; Guillot, Stéphane; Ganino, Clément

    2015-04-01

    prograde path, leading to a complete dehydration at the pressure peak conditions, (25 kbar and 510°C). The amount of water released during this stage is about 20 g/dm3. In this example, no hydration event is recorded during the exhumation, explaining the good preservation of the anhydrous eclogite. This study shows that garnet thermobarometry in eclogite may be used as a proxy for progressive oceanic crust dehydration as suggested by the models of Baxter & Caddick (2014). In contrast to such models, the estimations proposed in the present study are based on the measured composition of local domains in rock-samples and not on average bulk rock compositions. Complete dehydration of eclogites around 75 km corresponds to the maximum depth of most exhumed oceanic eclogites except for a few special cases. Moreover the distribution of seismicity along the slab shows that only few earthquakes do occur in the crust beyond this limit as compared to the seismicity above it. Consequently this example from a natural sample strongly suggests that the eclogite dehydration at this depth can cause slab fracturation and consequently enhance eclogite exhumation. Baxter, E.F. & Caddick, M.J. 2013. Garnet growth as a proxy for progressive subduction zone dehydration. Geology, 41, 643-646 Lanari, P., Vidal, O., De Andrade, V., Dubacq, B., Lewin, E., Grosch, E.G. & Schwartz, S. 2014. XMapTools: A MATLAB©-based program for electron microprobe X-ray image processing and geothermobarometry. Computers & Geosciences, 62, 227-240 Loury, C., Rolland, Y., Guillot, S., Mikolaichuk, A., Lanari, P., Bruguier, O. & Bosch, D. in press. Crustal-scale structure of South Tien Shan : implications for subduction polarity and Cenozoic reactivation. Geological Society of London, special publications

  3. Fracture problem of a nonhomogeneous high temperature superconductor slab based on real fundamental solutions

    NASA Astrophysics Data System (ADS)

    Gao, Zhiwen; Zheng, Zhiye; Li, Xueyi

    2015-12-01

    To analyze the fracture problem of the nonhomogeneous high temperature superconductor (HTS) slab under electromagnetic force, we derive the real fundamental solutions based on eigenvalue and eigenvector analyses. The superconductor E-J constitutive law is characterized by the Bean model where the critical current density is independent of the flux density. Fracture analysis is performed by the methods of singular integral equations which are solved numerically by Lobatto-Chybeshev collocation method. Numerical results of the stress intensity factor (SIF) are obtained. Moreover, the crack opening displacement (COD) can be obtained by numerical integration dislocation density functions. The effects of the thickness ratio, HTS material nonhomogeneous parameters, applied magnetic field and critical current density on SIF and COD are discussed. The present work could theoretically provide quantitative predictions of the fracture mechanism of the nonhomogeneous HTS.

  4. Subduction of Fracture Zones control mantle melting and geochemical signature above slabs

    NASA Astrophysics Data System (ADS)

    Constantin Manea, Vlad; Leeman, William; Gerya, Taras; Manea, Marina; Zhu, Guizhi

    2014-05-01

    The geochemistry of arc volcanics proximal to oceanic fracture zones (FZs) is consistent with higher than normal fluid inputs to arc magma sources. Here, enrichment of boron (B/Zr) in volcanic arc lavas is used to evaluate relative along-strike inputs of slab-derived fluids in the Aleutian, Andean, Cascades, and Trans-Mexican arcs. Significant B/Zr spikes coincide with subduction of prominent FZs in the relatively cool Aleutian and Andean subduction zones, but not in the relatively warm Cascadia and Mexican subduction zones, suggesting that FZ subduction locally enhances fluid introduction beneath volcanic arcs, and retention of fluids to sub-arc depths diminishes with subduction zone thermal gradient. Geodynamic treatments of lateral inhomogeneities in subducting plates have not previously considered how FZs may influence the melt and fluid distribution above the slab. Using high-resolution three-dimensional coupled petrological-thermomechanical numerical simulations of subduction, we show that fluids, including melts and water, concentrate in areas where fracture zones are subducted, resulting in along-arc variability in magma source compositions and processes.

  5. Ray-tracing technique and imaging properties by a PC slab with neff=-1

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Chen, Jiabi; Qian, W.

    2008-12-01

    In recent years, negative refractive media as the representation of new electromagnetic medium has become the front and the very popular researching field, and the production of the flat lens is one of its major applications. In our study, the imaging behaviors by two-dimensional photonic crystal slabs have been investigated systematically. We suggest a ray-tracing technique to discuss the action of photonic crystal slab with negative refraction. The propagation of electromagnetic waves in two-dimensional hexagonal lattice photonic crystal slab is investigated through dispersion characteristics analysis and numerical simulation of field patterns. Imaging and focusing with effective negative refractive index of -1 have been observed in these systems for both polarized waves, that is TE- and TM-polarized point source be considered simultaneously. Based on the exact finite-difference time-domain method to perform numerical simulation and physical analysis, we have demonstrated that the two-dimensional photonic crystal we designed can realize nearly perfect imaging with TM-polarized point source in the near field and far field, and the results are consistent with the ray-tracing technique quite well, while to TE-polarized point source the imaging is not perfect although it have neff=-1 in the same direction.

  6. Techniques for increasing boron fiber fracture strain

    NASA Technical Reports Server (NTRS)

    Dicarlo, J. A.

    1977-01-01

    Improvement in the strain-to-failure of CVD boron fibers is shown possible by contracting the tungsten boride core region and its inherent flaws. The results of three methods are presented in which etching and thermal processing techniques were employed to achieve core flaw contraction by internal stresses available in the boron sheath. After commercially and treatment induced surface flaws were removed from 203 micrometers (8 mil) fibers, the core flaw was observed to be essentially the only source of fiber fracture. Thus, fiber strain-to-failure was found to improve by an amount equal to the treatment induced contraction on the core flaw. Commercial feasibility considerations suggest as the most cost effective technique that method in which as-produced fibers are given a rapid heat treatment above 700 C. Preliminary results concerning the contraction kinetics and fracture behavior observed are presented and discussed both for high vacuum and argon gas heat treatment environments.

  7. A novel phase retrieval technique based on propagation diversity via a dielectric slab.

    PubMed

    Soldovieri, Francesco; Leone, Giovanni; Pierri, Rocco

    2008-05-12

    This paper deals with a novel technique to determine the far field of an aperture starting from the knowledge of two near-field intensity data sets collected over the same measurement plane. The diversity between the two intensity data sets is achieved by ensuring different conditions of the near field propagation between the aperture and the measurement plane. In particular, one measurement is performed under free-space propagation condition while the second one is performed by exploiting a dielectric slab, with known properties, filling partly the space between the aperture and the measurement plane. A phase retrieval technique, that faces a non linear inverse problem, is solved by assuming as unknown the plane wave spectrum of the aperture field. The feasibility of the novel approach is presented also in comparison with the usual near field phase retrieval technique exploiting measurements of the near field intensity over two scanning planes.

  8. Fracture detection in crystalline rock using ultrasonic reflection techniques: Volume 1

    SciTech Connect

    Palmer, S.P. )

    1982-11-01

    This research was initiated to investigate using ultrasonic seismic reflection techniques to detect fracture discontinuities in a granitic rock. Initial compressional (P) and shear (SH) wave experiments were performed on a 0.9 {times} 0.9 {times} 0.3 meter granite slab in an attempt to detect seismic energy reflected from the opposite face of the slab. It was found that processing techniques such as deconvolution and array synthesis could improve the standout of the reflection event. During the summers of 1979 and 1980 SH reflection experiments were performed at a granite quarry near Knowles, California. The purpose of this study was to use SH reflection methods to detect an in situ fracture located one to three meters behind the quarry face. These SH data were later analyzed using methods similar to those applied in the laboratory. Interpretation of the later-arriving events observed in the SH field data as reflections from a steeply-dipping fracture was inconclusive. 41 refs., 43 figs., 7 tabs.

  9. Suture Bridge Fixation Technique for Posterior Cruciate Ligament Avulsion Fracture.

    PubMed

    Lee, Kwang Won; Yang, Dae Suk; Lee, Gyu Sang; Choy, Won Sik

    2015-12-01

    We presented a surgical technique including a suture bridge technique with relatively small incision for the reduction and fixation of posterior ligament avulsion fractures. A suture anchor was used to hold the avulsed fragment and a knotless anchor was used to continuously compress the bony fragment into the fracture site, thereby maintaining reduction during healing.

  10. Improving clinical examination in acute tibial fractures by enhancing visual cues: the case for always 'cutting back' a tibial back-slab and marking the dorsalis pedis pulse.

    PubMed

    Thomas, Alasdair; Kimber, Cheryl; Bramwell, Donald; Jaarsma, Ruurd

    2016-08-01

    Look, feel, move is a simple and widely taught sequence to be followed when undertaking a clinical examination in orthopaedics (Maher et al., 1994; McRae, 1999; Solomon et al., 2010). The splinting of an acute tibial fracture with a posterior back-slab is also common practice; with the most commonly taught design involving covering the dorsum of the foot with bandaging (Charnley, 1950; Maher et al., 1994; McRae, 1989). We investigated the effect of the visual cues provided by exposing the dorsum of the foot and marking the dorsalis pedis pulse. We used a clinical simulation in which we compared the quality of the recorded clinical examination undertaken by 30 nurses. The nurses were randomly assigned to assess a patient with either a traditional back-slab or one in which the dorsal bandaging had been cut back and the dorsalis pedis pulse marked. We found that the quality of the recorded clinical examination was significantly better in the cut-back group. Previous studies have shown that the cut-back would not alter the effectiveness of the back-slab as a splint (Zagorski et al., 1993). We conclude that all tibial back-slabs should have the bandaging on the dorsum of the foot cut back and the location of the dorsalis pedis pulse marked. This simple adaptation will improve the subsequent clinical examinations undertaken and recorded without reducing the back-slab's effectiveness as a splint.

  11. A repositioning technique for nasal fracture using the little finger.

    PubMed

    Ichida, Masayuki; Komuro, Yuzo; Koizumi, Takuya; Shimizu, Azusa; Yanai, Akira

    2008-11-01

    A nasal bone fracture is usually repositioned using either Walsham or Asch forceps. However, accurate repositioning is often difficult. We therefore performed a repositioning technique using the little finger in 10 patients with a new nasal fracture. The results were satisfactory in all of the patients. Although medical experts may consider our method to be primitive, we believe that our method is both safe and effective, because the operator can recognize both the fractured part and its actual condition using the little finger. With this method, the occurrence of unnecessary new fractures can be prevented, in addition to minimizing the degree of mucosal damage and the occurrence of nasal hemorrhage. Furthermore, we consider that this technique can also reduce the occurrence of postoperative deformities due to the reduced mucosal contracture with this treatment modality. Even if the use of an instrument is deemed necessary, such as in treating saddle-nose-type fractures, initially feeling the fracture with the little finger will still allow for a more precise fracture reduction. We therefore consider our method to be both safe and effective at the initial stage of diagnosis and for the treatment of patients presenting with nasal bone fractures.

  12. Re-attachment of anterior fractured teeth: fracture strength using different techniques.

    PubMed

    Reis, A; Francci, C; Loguercio, A D; Carrilho, M R; Rodriques Filho, L E

    2001-01-01

    Fracture of anterior teeth by trauma is a common problem in children and teenagers. Complex metal-ceramic crowns with considerable loss of remaining sound structure are no longer necessary due to adhesive techniques, such as composite restorations and re-attachment techniques. This study compared the fracture strength of sound and restored anterior teeth using a resin composite and four re-attachment techniques. A "one bottle" adhesive system (One-Step, BISCO) and a dual cure resin cement (Duo-Link, BISCO) were applied. Thirty-five sound permanent lower central incisors were fractured by an axial load applied to the buccal area and randomly divided into five groups. The teeth were restored as follows: 1) bonded only = just bonding the fragment; 2) chamfer-group = after bonding, a chamfer was prepared on the enamel at the bonding line and filled with composite; 3) overcontour group = after bonding, a thin composite overcontour was applied on the buccal surface around the fracture line; 4) internal dentinal groove = before bonding, an internal groove was made and filled with a resin composite; 5) resin composite group = after a bevel preparation on the enamel edge, the adhesive system was applied and the fractured part of the teeth rebuilt by resin composite. Restored teeth were subjected to the same loading in the same buccal area. Fracture strength after restorative procedure was expressed as a percentage of the original fracture strength and the results analyzed by Kruskal-Wallis statistical analysis. The mean percentages of fracture strength were: Group 1: 37.09%, Group 2: 60.62%, Group 3: 97.2%, Group 4: 90.54% and Group 5: 95.8%. It was concluded that the re-attachment techniques used in Groups 3 and 4, as well as the composite restored group (Group 5), were statistically similar and reached the highest fracture resistance, similar to the fracture resistance of sound teeth.

  13. Location of hydraulic fractures using microseismic techniques

    SciTech Connect

    Albright, J.A.; Pearson, C.F.

    1980-01-01

    Microearthquakes with magnitudes ranging between -6 and -2 have been observed in three successive massive injections of water at the Hot Dry Rock Geothermal Energy demonstration site at Fenton Hill, New Mexico. The injection was part of a program to increase the heat transfer area of hydraulic fractures and to decrease the flow-through impedance between wells. The microearthquakes were used in mapping the location of the extended hydraulic fractures. A downhole triaxial system positioned approximately 200 m vertically above the injection point in a shut-in production well was used for detection. The microearthquakes occurred in a north-northwest striking zone 400 m in length passing through the injection point. During a third substantially larger injection, microearthquakes occurred in a dispersed volume at distances as great as 800 m from the zone active in the first two injections.

  14. A Novel Technique in Restoring Fractured Anterior Teeth

    PubMed Central

    K, Rajavardhan; Sankar, A.J. Sai; Shaik, Tanveer Ahmed; V, Naveen Kumar; K, Raj Kumar

    2014-01-01

    Trauma to the anterior teeth is a common phenomenon in young children and in adolescents. Uncomplicated crown fracture to the permanent teeth has an intense effect not only on the patient’s appearance, but also on function and speech. This case report describes a novel technique in restoring an uncomplicated fractured maxillary anterior tooth in a young patient with direct composite, which is economical and requires less chair side time. PMID:24701546

  15. Metacarpal Neck Fractures: A Review of Surgical Indications and Techniques

    PubMed Central

    Padegimas, Eric M.; Warrender, William J.; Jones, Christopher M.; Ilyas, Asif M.

    2016-01-01

    Context Hand injuries are a common emergency department presentation. Metacarpal fractures account for 40% of all hand fractures and can be seen in the setting of low or high energy trauma. The most common injury pattern is a metacarpal neck fracture. In this study, the authors aim to review the surgical indications for metacarpal neck fractures, the fixation options available along with the risk and benefits of each. Evidence Acquisition Literature review of the different treatment modalities for metacarpal neck fractures. Review focuses on surgical indications and the risks and benefits of different operative techniques. Results The indications for surgery are based on the amount of dorsal angulation of the distal fragment. The ulnar digits can tolerate greater angulation as the radial digits more easily lose grip strength. The most widely utilized fixation techniques are pinning with k-wires, dorsal plating, or intramedullary fixation. There is currently no consensus on an optimal fixation technique as surgical management has been found to have a complication rate up to 36%. Plate and screw fixation demonstrated especially high complication rates. Conclusions Metacarpal neck fractures are a common injury in young and active patients that results in substantial missed time from work. While the surgical indications are well-described, there is no consensus on the optimal treatment modality because of high complication rates. Dorsal plating has higher complication rates than closed reduction and percutaneous pinning, but is necessary in comminuted fractures. The lack of an ideal fixation construct suggests that further study of the commonly utilized techniques as well as novel techniques is necessary. PMID:27800460

  16. Development of Reservoir Characterization Techniques and Production Models for Exploiting Naturally Fractured Reservoirs

    SciTech Connect

    Wiggins, Michael L.; Brown, Raymon L.; Civan, Frauk; Hughes, Richard G.

    2001-08-15

    Research continues on characterizing and modeling the behavior of naturally fractured reservoir systems. Work has progressed on developing techniques for estimating fracture properties from seismic and well log data, developing naturally fractured wellbore models, and developing a model to characterize the transfer of fluid from the matrix to the fracture system for use in the naturally fractured reservoir simulator.

  17. A Novel Approach in Security Using Gyration Slab with Watermarking Technique

    NASA Astrophysics Data System (ADS)

    Rupa, Ch.

    2016-09-01

    In this paper, a novel security approach is proposed to improve the security and robustness of the data. It uses three levels of security to protect the sensitive data. In the first level, the data is to be protected by Gyration slab encryption algorithm. Result of the first level has to be embedded into an image as original using our earlier paper concept PLSB into a second level of security. The resultant image from the second level is considered as watermark Image. In the third level, the watermark image is embedded into the original image. Here watermark image and original image are similar. The final output of the proposed security approach is a watermarked image which holds the stego image. This method provides more security and robustness than the existing approaches. The main properties of the proposed approach are Gyration slab operations and watermark image and original image are similar. These can reduce the Brute-force attack and improve the confusion and diffusion principles. The main strengths of this paper are cryptanalysis, steganalysis, watermark analysis with reports.

  18. Modelling of 3D fractured geological systems - technique and application

    NASA Astrophysics Data System (ADS)

    Cacace, M.; Scheck-Wenderoth, M.; Cherubini, Y.; Kaiser, B. O.; Bloecher, G.

    2011-12-01

    All rocks in the earth's crust are fractured to some extent. Faults and fractures are important in different scientific and industry fields comprising engineering, geotechnical and hydrogeological applications. Many petroleum, gas and geothermal and water supply reservoirs form in faulted and fractured geological systems. Additionally, faults and fractures may control the transport of chemical contaminants into and through the subsurface. Depending on their origin and orientation with respect to the recent and palaeo stress field as well as on the overall kinematics of chemical processes occurring within them, faults and fractures can act either as hydraulic conductors providing preferential pathways for fluid to flow or as barriers preventing flow across them. The main challenge in modelling processes occurring in fractured rocks is related to the way of describing the heterogeneities of such geological systems. Flow paths are controlled by the geometry of faults and their open void space. To correctly simulate these processes an adequate 3D mesh is a basic requirement. Unfortunately, the representation of realistic 3D geological environments is limited by the complexity of embedded fracture networks often resulting in oversimplified models of the natural system. A technical description of an improved method to integrate generic dipping structures (representing faults and fractures) into a 3D porous medium is out forward. The automated mesh generation algorithm is composed of various existing routines from computational geometry (e.g. 2D-3D projection, interpolation, intersection, convex hull calculation) and meshing (e.g. triangulation in 2D and tetrahedralization in 3D). All routines have been combined in an automated software framework and the robustness of the approach has been tested and verified. These techniques and methods can be applied for fractured porous media including fault systems and therefore found wide applications in different geo-energy related

  19. Novel Matricing Technique for Management of Fractured Cusp Conundrum – A Clinician’s Corner

    PubMed Central

    Mittal, Priya Ramesh

    2016-01-01

    Longitudinal tooth fracture can be classified as craze lines, fractured cusp, cracked tooth, split tooth and vertical root fracture based on extent and severity of the fracture line. The most common type of longitudinal tooth fracture is fractured cusp that poses the treatment dilemma. Retention of the fractured cusp segment temporarily with matrix band followed by permanent bonded restoration and finally removal of tooth fragment during crown preparation is a novel technique. This paper throws light on a matricing and holding technique for the management of supra-crestally fractured palatal cusp of maxillary first premolar in a 29-year-old Asian male. PMID:27190970

  20. Determination of dynamic fracture toughness using a new experimental technique

    NASA Astrophysics Data System (ADS)

    Cady, Carl M.; Liu, Cheng; Lovato, Manuel L.

    2015-09-01

    In other studies dynamic fracture toughness has been measured using Charpy impact and modified Hopkinson Bar techniques. In this paper results will be shown for the measurement of fracture toughness using a new test geometry. The crack propagation velocities range from ˜0.15 mm/s to 2.5 m/s. Digital image correlation (DIC) will be the technique used to measure both the strain and the crack growth rates. The boundary of the crack is determined using the correlation coefficient generated during image analysis and with interframe timing the crack growth rate and crack opening can be determined. A comparison of static and dynamic loading experiments will be made for brittle polymeric materials. The analysis technique presented by Sammis et al. [1] is a semi-empirical solution, however, additional Linear Elastic Fracture Mechanics analysis of the strain fields generated as part of the DIC analysis allow for the more commonly used method resembling the crack tip opening displacement (CTOD) experiment. It should be noted that this technique was developed because limited amounts of material were available and crack growth rates were to fast for a standard CTOD method.

  1. In-vitro Evaluation of Fracture Strength Recovery of Reattached Anterior Fractured Tooth Fragment Using Different Re-Attachment Techniques

    PubMed Central

    Abdulkhayum, Abdulmujeeb; Munjal, Sumit; Babaji, Prashant; Chaurasia, Vishwajit Rampratap; Munjal, Seema; Lau, Himani; Olekar, Santosh T; Lau, Mayank

    2014-01-01

    Background: Traumatic injuries caused to anterior teeth are most common. Emergency management of fractured fragments is necessary, for preserving their vitalities and for retaining aesthetics in an economical way. Various methods are available for restoring fractured, uncomplicated teeth, such as reattachment of fractured fragments, composite restoration. But only limited data is available on evaluation of the strength of reattached fractured fragments. Hence, the present study was designed. Objectives: The objective of this study was to evaluate the fracture strength recovery of re-attached anterior fractured tooth fragment by using different re-attachment techniques. Methodology: Forty human upper central incisions were used in this study. The roots of the teeth were confined in a special device (holder) and adapted in a Universal Testing Machine. Load was applied to each tooth in bucco-lingual direction, by using a small stainless steel ball. The force which was required to fracture the tooth was recorded. Both the fragment and remaining fractured tooth was restored by using four reattachment techniques - simple reattachment, external chamfer, over contour and internal dentinal groove. Specimens were loaded in same pre-determined area which was used in procedure to obtain fragments. The force required to detach each fragment was recorded and it was correlated with the fracture strength of an intact tooth and that which was obtained after doing restorative procedures for all groups i.e. fracture strength recovery. Results: Technique I (simple reattachment) and Technique 2 (external chamfer) showed fracture strength recoveries of 44.3% and 60.6% respectively. However, these values were lower than those which were obtained by usingTechnique 3 (Over contour) -86.8% and Technique 4 (internal dentinal groove) -89.5%. Conclusion: Over contour and internal dentinal groove reattachment is a preferred technique as compared to the other reattachment techniques which were

  2. The development of in situ fracture toughness evaluation techniques in hydrogen environment

    SciTech Connect

    Wang, Jy-An John; Ren, Fei; Tan, Ting; Liu, Ken C

    2014-01-01

    Fracture behavior and fracture toughness are of great interest regarding reliability of hydrogen pipelines and storage tanks, however, many conventional fracture testing techniques are difficult to be realized under the presence of hydrogen, in addition to the inherited specimen size effect. Thus it is desired to develop novel in situ fracture toughness evaluation techniques to study the fracture behavior of structural materials in hydrogen environments. In this study, a torsional fixture was developed to utilize an emerging fracture testing technique, Spiral Notch Torsion Test (SNTT). The in situ testing results indicated that the exposure to H2 significantly reduces the fracture toughness of 4340 high strength steels by up to 50 percent. Furthermore, SNTT tests conducted in air demonstrated a significant fracture toughness reduction in samples subject to simulated welding heat treatment using Gleeble, which illustrated the effect of welding on the fracture toughness of this material.

  3. Current techniques for management of transverse displaced olecranon fractures

    PubMed Central

    den Hamer, Anniek; Heusinkveld, Maarten; Traa, Willeke; Oomen, Pim; Oliva, Francesco; Del Buono, Angelo; Maffulli, Nicola

    2015-01-01

    Summary Background displaced transverse fractures of the olecranon are the most common fractures occurring in the elbow in adults that requires operative intervention. Methods a literature search was performed on PubMed, Web of Science, Science Direct/Scopus, Google Scholar and Google using the keywords ‘olecranon’, ‘fracture’, ‘internal fixation’ and ‘tension band wiring’, with no limit for time or restrictions to language. Results thirty-one clinical articles were selected: 20 retrospective studies, 9 prospective cohort studies, and 2 randomized control trials. The CMS ranged from 18 to 66 (mean 41.68): overall, the quality of the studies was poor, and no moderate or good quality studies were found. The mean follow-up was 46.7 months (range 1 to 350 months). Several complications occurred after surgery: prominent hardware, skin breakdown, wire migration and infections occurred frequently. Removal of the hardware was required in 472 patients, usually after complaints, but also removal was routinely undertaken. Conclusions tension band wiring is still the most widely applied method to operatively manage olecranon fractures, with the transcortical method of using K-wires the most satisfactory. Plate fixation is a good alternative as complications are minimal. Other techniques using absorbable sutures are less investigated, but are promising, especially in children. PMID:26261793

  4. Temporary intra-operative reduction techniques for tibial fracture fixation: A review of the literature.

    PubMed

    Beazley, J C; Hull, P

    2010-12-01

    Accurate intra-operative reduction and maintenance of reduction is essential for successful fixation of tibial fractures. Although many tibial fractures can be reduced with minimal manipulation, numerous techniques have been described to facilitate fixation of more difficult fractures. These include use of a traction table, manual traction techniques, temporary distracters, reduction clamps and temporary unicortical plating. This article reviews the literature and assesses the options available for the temporary reduction and maintenance of reduction of tibial fractures prior to definitive fixation.

  5. Fast iterative, coupled-integral-equation technique for inhomogeneous profiled and periodic slabs.

    PubMed

    Magath, Thore; Serebryannikov, Andriy E

    2005-11-01

    A fast coupled-integral-equation (CIE) technique is developed to compute the plane-TE-wave scattering by a wide class of periodic 2D inhomogeneous structures with curvilinear boundaries, which includes finite-thickness relief and rod gratings made of homogeneous material as special cases. The CIEs in the spectral domain are derived from the standard volume electric field integral equation. The kernel of the CIEs is of Picard type and offers therefore the possibility of deriving recursions, which allow the computation of the convolution integrals occurring in the CIEs with linear amounts of arithmetic complexity and memory. To utilize this advantage, the CIEs are solved iteratively. We apply the biconjugate gradient stabilized method. To make the iterative solution process faster, an efficient preconditioning operator (PO) is proposed that is based on a formal analytical inversion of the CIEs. The application of the PO also takes only linear complexity and memory. Numerical studies are carried out to demonstrate the potential and flexibility of the CIE technique proposed. Though the best efficiency and accuracy are observed at either low permittivity contrast or high conductivity, the technique can be used in a wide range of variation of material parameters of the structures including when they contain components made of both dielectrics with high permittivity and typical metals.

  6. Fast iterative, coupled-integral-equation technique for inhomogeneous profiled and periodic slabs

    NASA Astrophysics Data System (ADS)

    Magath, Thore; Serebryannikov, Andriyâ E.

    2005-11-01

    A fast coupled-integral-equation (CIE) technique is developed to compute the plane-TE-wave scattering by a wide class of periodic 2D inhomogeneous structures with curvilinear boundaries, which includes finite-thickness relief and rod gratings made of homogeneous material as special cases. The CIEs in the spectral domain are derived from the standard volume electric field integral equation. The kernel of the CIEs is of Picard type and offers therefore the possibility of deriving recursions, which allow the computation of the convolution integrals occurring in the CIEs with linear amounts of arithmetic complexity and memory. To utilize this advantage, the CIEs are solved iteratively. We apply the biconjugate gradient stabilized method. To make the iterative solution process faster, an efficient preconditioning operator (PO) is proposed that is based on a formal analytical inversion of the CIEs. The application of the PO also takes only linear complexity and memory. Numerical studies are carried out to demonstrate the potential and flexibility of the CIE technique proposed. Though the best efficiency and accuracy are observed at either low permittivity contrast or high conductivity, the technique can be used in a wide range of variation of material parameters of the structures including when they contain components made of both dielectrics with high permittivity and typical metals.

  7. Three-wire fixation technique for displaced fifth metatarsal base fractures.

    PubMed

    Thomas, James L; Davis, Barry C

    2011-01-01

    Fractures of the tuberosity of the fifth metatarsal are the most common type of fifth metatarsal fractures. This particular fracture usually produces low morbidity and low rates of nonunion when treated nonoperatively. However, on occasion, significant displacement, comminution, or significant intra-articular involvement may warrant operative intervention. Multiple techniques have been described for the operative care of this fracture. We present a somewhat simplified fixation method for displaced fifth metatarsal fractures in a small set of patients who were all followed up to final healing of the fracture.

  8. Repair technique for fractured implant-supported metal-ceramic restorations: a clinical report.

    PubMed

    Wady, Amanda Fucci; Paleari, André Gustavo; Queiroz, Thallita Pereira; Margonar, Rogerio

    2014-10-01

    The fracture of porcelain structures have been related in either natural dentition or implant-supported restorations. Techniques using a composite resin or indirect methods can be used. This article presents a porcelain fracture on implant-supported metal-ceramic restoration. IPS Empress e.max laminate veneer restoration was used to repair the fracture. With this technique, it was possible to restore aesthetics and function, combined with low cost and patient satisfaction.

  9. Cortical screw support in femoral neck fractures. A radiographic analysis of 87 fractures with a new mensuration technique.

    PubMed

    Lindequist, S

    1993-06-01

    In 87 femoral neck fractures, operated on with 2 von Bahr screws and followed for up to 2 years, the positions of the fixating screws were determined with a new mensuration technique which compensates for the variations in hip rotation in routine radiographs. The union rate of the fractures was related to the position of the screws. A posterior placement of the proximal screw and an inferior placement of the distal screw in both the femoral head and neck improved the outcome substantially.

  10. Defense technique takes guesswork out of tight reservoir fracturing jobs

    SciTech Connect

    Duey, R.

    1996-05-01

    Enserch exploration and the Los Alamos National Laboratory are using a highly sensitive defense technology to map fractures in an East Texas field. A process known as nuclear test verification, using highly sophisticated detectors can actually map fractures as they occur.

  11. Recent advances in freeze-fracture electron microscopy: the replica immunolabeling technique

    PubMed Central

    2008-01-01

    Freeze-fracture electron microscopy is a technique for examining the ultrastructure of rapidly frozen biological samples by transmission electron microscopy. Of a range of approaches to freeze-fracture cytochemistry that have been developed and tried, the most successful is the technique termed freeze-fracture replica immunogold labeling (FRIL). In this technique, samples are frozen, fractured and replicated with platinum-carbon as in standard freeze fracture, and then carefully treated with sodium dodecylsulphate to remove all the biological material except a fine layer of molecules attached to the replica itself. Immunogold labeling of these molecules permits their distribution to be seen superimposed upon high resolution planar views of membrane structure. Examples of how this technique has contributed to our understanding of lipid droplet biogenesis and function are discussed. PMID:18385807

  12. Analysis of compressive fracture in rock using statistical techniques

    SciTech Connect

    Blair, S.C.

    1994-12-01

    Fracture of rock in compression is analyzed using a field-theory model, and the processes of crack coalescence and fracture formation and the effect of grain-scale heterogeneities on macroscopic behavior of rock are studied. The model is based on observations of fracture in laboratory compression tests, and incorporates assumptions developed using fracture mechanics analysis of rock fracture. The model represents grains as discrete sites, and uses superposition of continuum and crack-interaction stresses to create cracks at these sites. The sites are also used to introduce local heterogeneity. Clusters of cracked sites can be analyzed using percolation theory. Stress-strain curves for simulated uniaxial tests were analyzed by studying the location of cracked sites, and partitioning of strain energy for selected intervals. Results show that the model implicitly predicts both development of shear-type fracture surfaces and a strength-vs-size relation that are similar to those observed for real rocks. Results of a parameter-sensitivity analysis indicate that heterogeneity in the local stresses, attributed to the shape and loading of individual grains, has a first-order effect on strength, and that increasing local stress heterogeneity lowers compressive strength following an inverse power law. Peak strength decreased with increasing lattice size and decreasing mean site strength, and was independent of site-strength distribution. A model for rock fracture based on a nearest-neighbor algorithm for stress redistribution is also presented and used to simulate laboratory compression tests, with promising results.

  13. Hydraulic fracturing method employing a fines control technique

    SciTech Connect

    Stowe, L.R.

    1986-11-18

    A method is described for controlling fines or sand in an unconsolidated or loosely consolidated formation or reservoir penetrated by at least one wellbore where hydraulic fracturing is used in combination with control of the critical salinity rate and the critical fluid flow velocity. The method comprises: (a) placing at least one wellbore in the reservoir; (b) hydraulically fracturing the formation via the wellbore with a fracturing fluid which creates at least one fracture; (c) placing a proppant comprising a gravel pack into the fracture; (d) determining the critical salinity rate and the critical fluid flow velocity of the formation or reservoir surrounding the wellbore; (e) injecting a saline solution into the formation or reservoir at a velocity exceeding the critical fluid flow velocity and at a saline concentration sufficient to cause the fines or particles to be transferred and fixed deep wihtin the formation or reservoir without plugging the formation, fracture, or wellbore; and (f) producing a hydrocarbonaceous fluid from the formation or reservoir at a velocity such that the critical flow velocity is not exceeded deep within the formation, fracture, or wellbore.

  14. Optimization of hydraulic fracturing techniques for eastern Devonian shales

    SciTech Connect

    Swartz, G.; Ahmed, U.

    1982-01-01

    A laboratory test program was performed to evaluate the physical characteristics of several Devonian shale reservoirs and the interaction between the fracturing fluids and the reservoir formation. Data presented in this paper characterizes the Devonian shale reservoir as a dense material with low porosity and permeability. Matrix permeability damage tests have shown that nitrogen foam was less damaging than was CO/sub 2//water mixture as a hydraulic fracturing fluid.

  15. Novel Technique for Treatment of Calcaneal Tuberosity Fractures.

    PubMed

    Yan, Alan Y; Bertrand, Todd E; Zura, Robert D; Adams, Samuel B; Parekh, Selene G

    2016-01-01

    Calcaneal tuberosity fractures comprise only 1% to 2% of all calcaneal fractures. Treatment of these injuries has traditionally included open reduction and internal fixation with various means including lag screws, suture anchors, and K-wires. This article reports on a series of cases treated with excision of the tuberosity fragment with repair of the Achilles tendon supplemented by a flexor hallucis longus tendon transfer. PMID:27082890

  16. The development of in situ fracture toughness evaluation techniques in hydrogen environment

    DOE PAGES

    Wang, John Jy-An; Ren, Fei; Tan, Tin; Liu, Ken

    2014-12-19

    Reliability of hydrogen pipelines and storage tanks is significantly influenced by the mechanical performance of the structural materials exposed in the hydrogen environment. Fracture behavior and fracture toughness are of specific interest since they are relevant to many catastrophic failures. However, many conventional fracture testing techniques are difficult to be realized under the presence of hydrogen. Thus it is desired to develop novel in situ techniques to study the fracture behavior of structural materials in hydrogen environments. In this study, special testing apparatus were designed to facilitate in situ fracture testing in H2. A torsional fixture was developed to utilizemore » an emerging fracture testing technique, Spiral Notch Torsion Test (SNTT). The design concepts will be discussed. Preliminary in situ testing results indicated that the exposure to H2 significantly reduces the fracture toughness of 4340 high strength steels by up to 50 percent. Furthermore, SNTT tests conducted in air demonstrated a significant fracture toughness reduction in samples subject to simulated welding heat treatment using Gleeble, which illustrated the effect of welding on the fracture toughness of this material.« less

  17. The development of in situ fracture toughness evaluation techniques in hydrogen environment

    SciTech Connect

    Wang, John Jy-An; Ren, Fei; Tan, Tin; Liu, Ken

    2014-12-19

    Reliability of hydrogen pipelines and storage tanks is significantly influenced by the mechanical performance of the structural materials exposed in the hydrogen environment. Fracture behavior and fracture toughness are of specific interest since they are relevant to many catastrophic failures. However, many conventional fracture testing techniques are difficult to be realized under the presence of hydrogen. Thus it is desired to develop novel in situ techniques to study the fracture behavior of structural materials in hydrogen environments. In this study, special testing apparatus were designed to facilitate in situ fracture testing in H2. A torsional fixture was developed to utilize an emerging fracture testing technique, Spiral Notch Torsion Test (SNTT). The design concepts will be discussed. Preliminary in situ testing results indicated that the exposure to H2 significantly reduces the fracture toughness of 4340 high strength steels by up to 50 percent. Furthermore, SNTT tests conducted in air demonstrated a significant fracture toughness reduction in samples subject to simulated welding heat treatment using Gleeble, which illustrated the effect of welding on the fracture toughness of this material.

  18. Lower Extremity Fracture Reduction: Tips, Tricks, and Techniques So That You Leave the Operating Room Satisfied.

    PubMed

    Mir, Hassan R; Boulton, Christina L; Russell, George V; Archdeacon, Michael

    2016-01-01

    It can be challenging for surgeons to obtain proper alignment and to create stable constructs for the maintenance of many lower extremity fractures until union is achieved. Whether lower extremity fractures are treated with plates and screws or intramedullary nails, there are numerous pearls that may help surgeons deal with these difficult injuries. Various intraoperative techniques can be used for lower extremity fracture reduction and stabilization. The use of several reduction tools, tips, and tricks may facilitate the care of lower extremity fractures and, subsequently, improve patient outcomes. PMID:27049180

  19. Slab reformer

    NASA Technical Reports Server (NTRS)

    Spurrier, Francis R. (Inventor); DeZubay, Egon A. (Inventor); Murray, Alexander P. (Inventor); Vidt, Edward J. (Inventor)

    1984-01-01

    Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot comubstion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

  20. Slab reformer

    DOEpatents

    Spurrier, Francis R.; DeZubay, Egon A.; Murray, Alexander P.; Vidt, Edward J.

    1985-03-12

    Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot combustion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

  1. Slab reformer

    DOEpatents

    Spurrier, Francis R.; DeZubay, Egon A.; Murray, Alexander P.; Vidt, Edward J.

    1984-02-07

    Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot comubstion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

  2. Slab reformer

    DOEpatents

    Spurrier, F.R.; DeZubay, E.A.; Murray, A.P.; Vidt, E.J.

    1984-02-07

    Slab-shaped high efficiency catalytic reformer configurations are disclosed particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot combustion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant. 14 figs.

  3. Computer assisted preoperative planning of bone fracture reduction: Simulation techniques and new trends.

    PubMed

    Jiménez-Delgado, Juan J; Paulano-Godino, Félix; PulidoRam-Ramírez, Rubén; Jiménez-Pérez, J Roberto

    2016-05-01

    The development of support systems for surgery significantly increases the likelihood of obtaining satisfactory results. In the case of fracture reduction interventions these systems enable surgery planning, training, monitoring and assessment. They allow improvement of fracture stabilization, a minimizing of health risks and a reduction of surgery time. Planning a bone fracture reduction by means of a computer assisted simulation involves several semiautomatic or automatic steps. The simulation deals with the correct position of osseous fragments and fixation devices for a fracture reduction. Currently, to the best of our knowledge there is no computer assisted methods to plan an entire fracture reduction process. This paper presents an overall scheme of the computer based process for planning a bone fracture reduction, as described above, and details its main steps, the most common proposed techniques and their main shortcomings. In addition, challenges and new trends of this research field are depicted and analyzed.

  4. Impacted and Fractured Biliary Basket: A Second Basket Rescue Technique.

    PubMed

    Benatta, Mohammed Amine; Desjeux, Ariane; Barthet, Marc; Grimaud, Jean Charles; Gasmi, Mohamed

    2016-01-01

    A 59-year-old woman was treated with ERCP, ES, and biliary plastic stent, for large and multiple common bile duct stones. During a second ERCP basket extraction was impacted with a round entrapped stone. The basket handle was cut off; a metal sheath of extraendoscopic lithotriptor was advanced over the basket. The mechanical lithotripsy was complicated with basket traction wires fracturing, without breakage of the stone. A rescue standard basket was pushed until it caught the basket/stone complex. Using this method disengagement of the whole fractured basket/stone complex was achieved without need of surgery. It is the third case reported in the English literature. PMID:27293442

  5. DEVELOPMENT OF RESERVOIR CHARACTERIZATION TECHNIQUES AND PRODUCTION MODELS FOR EXPLOITING NATURALLY FRACTURED RESERVOIRS

    SciTech Connect

    Michael L. Wiggins; Raymon L. Brown; Faruk Civan; Richard G. Hughes

    2002-12-31

    For many years, geoscientists and engineers have undertaken research to characterize naturally fractured reservoirs. Geoscientists have focused on understanding the process of fracturing and the subsequent measurement and description of fracture characteristics. Engineers have concentrated on the fluid flow behavior in the fracture-porous media system and the development of models to predict the hydrocarbon production from these complex systems. This research attempts to integrate these two complementary views to develop a quantitative reservoir characterization methodology and flow performance model for naturally fractured reservoirs. The research has focused on estimating naturally fractured reservoir properties from seismic data, predicting fracture characteristics from well logs, and developing a naturally fractured reservoir simulator. It is important to develop techniques that can be applied to estimate the important parameters in predicting the performance of naturally fractured reservoirs. This project proposes a method to relate seismic properties to the elastic compliance and permeability of the reservoir based upon a sugar cube model. In addition, methods are presented to use conventional well logs to estimate localized fracture information for reservoir characterization purposes. The ability to estimate fracture information from conventional well logs is very important in older wells where data are often limited. Finally, a desktop naturally fractured reservoir simulator has been developed for the purpose of predicting the performance of these complex reservoirs. The simulator incorporates vertical and horizontal wellbore models, methods to handle matrix to fracture fluid transfer, and fracture permeability tensors. This research project has developed methods to characterize and study the performance of naturally fractured reservoirs that integrate geoscience and engineering data. This is an important step in developing exploitation strategies for

  6. Backstroke technique: an effective way to improve the healing of tibia fracture.

    PubMed

    Lee, Qi; Zeng, Bing-Fang; Luo, Cong-Feng; Wang, Jin-Wu; Lu, Nan-Ji

    2006-10-01

    To assess the method and results of applying a backstroke technique, we treated 43 patients with tibial shaft fracture using unreamed tibial nails (UTN). Of these patients, 27 suffered a closed fracture and 16 an open fracture. After the operation, the effect of treatment was evaluated: 42 of 43 cases were followed up from four to 18 months, averaging 13.6 months. The four-month and 12-month healing rates of open fracture were 54.6 and 80.9%, respectively, the former of which is significantly higher than the average rate of the AO/ASIF multicentre study. Our results indicate that applying a backstroke technique in treating tibial shaft fracture with UTN can improve the healing rate and reduce complications. PMID:16628441

  7. [Periprosthetic humeral fractures: Strategies and techniques of revision arthroplasty].

    PubMed

    Kirchhoff, C; Beirer, M; Brunner, U

    2016-04-01

    The primary aims when performing revision arthroplasty of periprosthetic humeral fractures (PHF) are preservation of bone stock, achieving fracture healing and preserving a stable prosthesis with the focus on regaining the preoperative shoulder-arm function. The indications for revision arthroplasty are given in PHF in combination with loosening of the stem. In addition, further factors must be independently clarified in the case of an anatomical arthroplasty. In this context secondary glenoid erosion as well as rotator cuff insufficiency are potential factors for an extended revision procedure. For the performance of revision surgery modular revision sets including long stems, revision glenoid and metaglene components as well as plate and cerclage systems are obligatory besides the explantation instrumentation. Despite a loosened prosthesis, a transhumeral removal of the stem along with a subpectoral fenestration are often required. Length as well as bracing of revision stems need to bridge the fracture by at least twice the humeral diameter. Moreover, in many cases a combined procedure using an additional distal open reduction and internal fixation (ORIF) plus cable cerclages as well as biological augmentation might be needed. Assuming an adequate preparation, the experienced surgeon is able to achieve a high fracture union rate along with an acceptable or even good shoulder function and to avoid further complications.

  8. Effect of Different Instrumentation Techniques on Vertical Root Fracture Resistance of Endodontically Treated Teeth

    PubMed Central

    Tavanafar, Saeid; Karimpour, Azadeh; Karimpour, Hamideh; Mohammed Saleh, Abdulrahman; Hamed Saeed, Musab

    2015-01-01

    Statement of the Problem Vertical root fractures are catastrophic events that often result in tooth extraction. Many contributing factor are associated with increasing incidence of vertical root fracture. Root canal preparation is one of the predisposing factors which can increase the root susceptibility to vertical fracture. Purpose The aim of this study was to compare the effects of three different instrumentation techniques on vertical root fracture resistance of endodontically treated teeth. Materials and Methods In this study, 120 freshly extracted mandibular premolar teeth of similar dimensions were decoronated and randomly divided into control (n=30), nickel-titanium hand K-file (HF, n=30), BioRaCe rotary file (BR, n=30), and WaveOne reciprocating single-file (WO, n=30) groups. After cleaning and shaping the root canals, AH26 was used as canal sealer, and obturation was completed using the continuous wave technique. The root canals were embedded vertically in standardised autopolymerising acrylic resin blocks, and subjected to a vertical load to cause vertical root fracture. The forces required to induce fractures were measured using a universal testing machine. ANOVA and Tukey’s post-hoc test were used to analyse the data. Results All experimental groups showed statistically significant reductions in fracture resistance as compared with the control group. There was a statistically significant difference between the HF and BR groups. The WO group did not differ significantly from the HF group or the BR group. Conclusion All three instrumentation techniques caused weakening of the structure of the roots, and rendered them susceptible to fracture under lesser load than unprepared roots. The fracture resistance of roots prepared with the single-file reciprocating technique was similar to that of those prepared with NiTi hand and rotary instrumentation techniques. PMID:26106635

  9. Locking plate fixation of distal femoral fractures is a challenging technique: a retrospective review

    PubMed Central

    Toro, Giuseppe; Calabrò, Giampiero; Toro, Antonio; de Sire, Alessandro; Iolascon, Giovanni

    2015-01-01

    Summary Distal femoral fractures have typically a bimodal occurrence: in young people due to a high-energy trauma and in older people related to a low-energy trauma. These fractures are associated to a very high morbidity and mortality in elderly. Distal femoral fractures might be treated with plates, intramedullary nails, external fixations, and prosthesis. However, difficulties in fracture healing and the rate of complications are important clinical issues. The purpose of this retrospective review was to present our experience in treatment of distal femoral fracture in a sample of older people in order to evaluate the technical pitfalls and strategies used to face up the fractures unsuccessfully treated with locking plates. We included people aged more than 65 years, with a diagnosis of distal femoral fracture, treated with locking plates. We considered ‘unsuccessfully treated’ the cases with healing problems or hardware failures. Of the 12 patients (9 females and 3 males; mean aged 68.75 ± 3.31 years) included, we observed 3 ‘unsuccessfully cases’, 2 due to nonunions and 1 due to an early hardware failure, all treated using a condylar blade plate with a bone graft. One patient obtained a complete fracture healing after 1 year and in the other cases there was a nonunion. We observed as most common technical pitfalls: inadequate plate lengthening, fracture bridging, and number of locking screws. The use of locking plates is an emerging technique to treat these fractures but it seems more challenging than expected. In literature there is a lack of evidences about the surgical management of distal femoral fractures that is still an important challenge for the orthopaedic surgeon that has to be able to use all the fixation devices available. PMID:27134634

  10. Two-Tension-Band Technique in Revision Surgery for Fixation Failure of Patellar Fractures.

    PubMed

    Xue, Zichao; Qin, Hui; Ding, Haoliang; Xu, Haitao; An, Zhiquan

    2016-01-01

    BACKGROUND Failed patellar fracture fixation is rare, and is usually attributed to technical errors. There are no specific details available on how to address this problem. We present our two-tension-band technique for fixing patellar fractures. MATERIAL AND METHODS Between March 2010 and March 2013, 4 men and 2 women with failed fixation patellar fractures were treated in our department. Their average age was 34 years (range 23-49 years). The initial fracture type was C1 in 3, C2 in 1, and C3 in 2, according to the AO classification. The initial fracture patterns included 3 transverse and 3 comminuted fractures. There were no open fractures. All patients underwent internal fixation with a modified anterior tension band (MATB) supplemented with cerclage wiring. All failures were caused by tension bands sliding past the tip of the Kirschner wires. The mean time between the primary and revision operations was 16.2 months (range 2-63 months). We revised the fractures by two-separate-tension-band technique. RESULTS The mean follow-up was 52 months (range 31-67 months). All patients healed radiographically without complications at an average of 14.7 weeks (range 8-20 weeks). The Bostman knee score was excellent in 3 and good in 3. All patients regained full extension and the mean range of flexion was 147.5° (135-155°). CONCLUSIONS Use of this two-tension-band technique can avoid technical errors and provide more secure fixation. We recommend it for both primary and revision surgery of patellar fractures. PMID:27485104

  11. Two-Tension-Band Technique in Revision Surgery for Fixation Failure of Patellar Fractures.

    PubMed

    Xue, Zichao; Qin, Hui; Ding, Haoliang; Xu, Haitao; An, Zhiquan

    2016-01-01

    BACKGROUND Failed patellar fracture fixation is rare, and is usually attributed to technical errors. There are no specific details available on how to address this problem. We present our two-tension-band technique for fixing patellar fractures. MATERIAL AND METHODS Between March 2010 and March 2013, 4 men and 2 women with failed fixation patellar fractures were treated in our department. Their average age was 34 years (range 23-49 years). The initial fracture type was C1 in 3, C2 in 1, and C3 in 2, according to the AO classification. The initial fracture patterns included 3 transverse and 3 comminuted fractures. There were no open fractures. All patients underwent internal fixation with a modified anterior tension band (MATB) supplemented with cerclage wiring. All failures were caused by tension bands sliding past the tip of the Kirschner wires. The mean time between the primary and revision operations was 16.2 months (range 2-63 months). We revised the fractures by two-separate-tension-band technique. RESULTS The mean follow-up was 52 months (range 31-67 months). All patients healed radiographically without complications at an average of 14.7 weeks (range 8-20 weeks). The Bostman knee score was excellent in 3 and good in 3. All patients regained full extension and the mean range of flexion was 147.5° (135-155°). CONCLUSIONS Use of this two-tension-band technique can avoid technical errors and provide more secure fixation. We recommend it for both primary and revision surgery of patellar fractures.

  12. Two-Tension-Band Technique in Revision Surgery for Fixation Failure of Patellar Fractures

    PubMed Central

    Xue, Zichao; Qin, Hui; Ding, Haoliang; Xu, Haitao; An, Zhiquan

    2016-01-01

    Background Failed patellar fracture fixation is rare, and is usually attributed to technical errors. There are no specific details available on how to address this problem. We present our two-tension-band technique for fixing patellar fractures. Material/Methods Between March 2010 and March 2013, 4 men and 2 women with failed fixation patellar fractures were treated in our department. Their average age was 34 years (range 23–49 years). The initial fracture type was C1 in 3, C2 in 1, and C3 in 2, according to the AO classification. The initial fracture patterns included 3 transverse and 3 comminuted fractures. There were no open fractures. All patients underwent internal fixation with a modified anterior tension band (MATB) supplemented with cerclage wiring. All failures were caused by tension bands sliding past the tip of the Kirschner wires. The mean time between the primary and revision operations was 16.2 months (range 2–63 months). We revised the fractures by two-separate-tension-band technique. Results The mean follow-up was 52 months (range 31–67 months). All patients healed radiographically without complications at an average of 14.7 weeks (range 8–20 weeks). The Bostman knee score was excellent in 3 and good in 3. All patients regained full extension and the mean range of flexion was 147.5° (135–155°). Conclusions Use of this two-tension-band technique can avoid technical errors and provide more secure fixation. We recommend it for both primary and revision surgery of patellar fractures. PMID:27485104

  13. Assessment of fracture-sampling techniques for laboratory tests on core

    USGS Publications Warehouse

    Severson, G.R.; Boernge, J.M.; ,

    1991-01-01

    As part of the site characterization work to be done at Yucca Mountain in Nye County, Nevada, a candidate site for the first mined-geologic repository for high-level nuclear waste, laboratory tests are proposed to evaluate fluid flow in single fractures. Laboratory and onsite tests were conducted to develop methods for collecting rock-core samples containing single fractures for the subsequent laboratory tests. Techniques for collecting rock cores with axial (parallel to the core axis) and radial (perpendicular to the core axis) fractures are discussed.

  14. Rigid Intramedullary Nailing of Femoral Shaft Fractures for Patients Age 12 and Younger: Indications and Technique.

    PubMed

    Martus, Jeffrey E

    2016-06-01

    Femoral shaft fractures are common injuries in the pediatric and adolescent age groups. Rigid intramedullary nailing is an excellent treatment option for older children and adolescents, particularly for length-unstable fractures and larger patients (>49 kg). Appropriate indications, contraindications, and preoperative assessment are described. The rigid nailing surgical technique is detailed including positioning, operative steps, pearls, and pitfalls. Complications and the reported outcomes of lateral trochanteric entry nailing are reviewed from the published series. PMID:27100036

  15. [Periprosthetic humeral fractures: Strategies and techniques for osteosynthesis].

    PubMed

    Kirchhoff, C; Brunner, U; Biberthaler, P

    2016-04-01

    The prevalence of periprosthetic humeral fractures (PHF) is currently low and accounts for 0.6-2.4%. Due to an increase in the rate of primary implantations a quantitative increase of PHF is to be expected in the near future. The majority of PHF occur intraoperatively during implantation with an increased risk for cementless stems and when performing total arthroplasty. Additional risk factors are in particular female gender and the severity of comorbidities. In contrast, postoperative PHF mostly due to low-energy falls, have a prevalence between 0.6% and 0.9% and are significantly less common. The prognosis and functional outcome following revision by open reduction internal fixation (ORIF) essentially depend on a thorough assessment of the indications for revision surgery, the operative treatment and the pretraumatic functional condition of the affected shoulder. In the armamentarium of periprosthetic ORIF of the humerus cerclage systems and locking implants as well as a combination of both play a central role. In comminuted fractures with extensive defect zones, severely thinned cortex or extensive osteolysis a biological augmentation of the ORIF should be considered. In this context when the indications are correctly interpreted, especially in the case of a stable anchored stem, various groups have reported that a high bony union rate can be achieved. As the treatment of PHF is complex it should be performed in dedicated centers in order to adequately address potential comorbidities, especially in the elderly population.

  16. New fracturing techniques reduce tight gas sand completion problems

    SciTech Connect

    Bruce, P.L.; Hunter, J.L. ); Kuhlman, R.D. ); Weinheimer, D.D. )

    1992-10-12

    This paper reports on new fracturing stimulation technology which contributed to solving problems in completing tight gas sands in the Carthage Cotton Valley field in Texas. These technologies included improved fluid systems, computer-controlled proppant placement, multiple isotope radioactive logs, mechanical properties logs, and innovative casing design. Drilling activity in the Carthage field commenced on a large scale in 1978 and 1979. At that time, the Natural Gas Policy Act of 1978 (NGPA) first allowed higher gas prices. In 1980, low-permeability sandstones officially were classified as tight gas sands by the Federal Energy Regulatory Commission (FERC). This classification qualified the sands for NGPA incentive gas prices. After the Texas Railroad Commission (RRC) changed the field rules to 320 acre spacing, another round of development drilling began. In 1981 and 1982, Pennzoil drilled and completed 22 infill development wells before the gas market crashed in 1982.

  17. The use of surface geophysical techniques to detect fractures in bedrock; an annotated bibliography

    USGS Publications Warehouse

    Lewis, Mark R.; Haeni, F.P.

    1987-01-01

    This annotated bibliography compiles references about the theory and application of surface geophysical techniques to locate fractures or fracture zones within bedrock units. Forty-three publications are referenced, including journal articles, theses, conference proceedings, abstracts, translations, and reports prepared by private contractors and U.S. Government agencies. Thirty-one of the publications are annotated. The remainder are untranslated foreign language articles, which are listed only as bibliographic references. Most annotations summarize the location, geologic setting, surface geophysical technique used, and results of a study. A few highly relevant theoretical studies are annotated also. Publications that discuss only the use of borehole geophysical techniques to locate fractures are excluded from this bibliography. Also excluded are highly theoretical works that may have little or no known practical application.

  18. Transpalatal screw traction: a simple technique for the management of sagittal fractures of the maxilla and palate.

    PubMed

    Ma, D; Guo, X; Yao, H; Chen, J

    2014-12-01

    Sagittal fractures of the maxilla and palate are uncommon in clinical practice. Current methods for the management of such fractures have advantages and limitations. The authors present the simple and practical technique of bilateral transpalatal screw traction to manage this fracture type.

  19. Influence of weak layer heterogeneity and slab properties on slab tensile failure propensity and avalanche release area

    NASA Astrophysics Data System (ADS)

    Gaume, J.; Chambon, G.; Eckert, N.; Naaim, M.; Schweizer, J.

    2015-04-01

    Dry-snow slab avalanches are generally caused by a sequence of fracture processes, including failure initiation in a weak snow layer underlying a cohesive slab followed by crack propagation within the weak layer (WL) and tensile fracture through the slab. During past decades, theoretical and experimental work has gradually increased our knowledge of the fracture process in snow. However, our limited understanding of crack propagation and fracture arrest propensity prevents the evaluation of avalanche release sizes and thus impedes hazard assessment. To address this issue, slab tensile failure propensity is examined using a mechanically based statistical model of the slab-WL system based on the finite element method. This model accounts for WL heterogeneity, stress redistribution by slab elasticity and possible tensile failure of the slab. Two types of avalanche release are distinguished in the simulations: (1) full-slope release if the heterogeneity is not sufficient to stop crack propagation and trigger a tensile failure within the slab; (2) partial-slope release if fracture arrest and slab tensile failure occur due to the WL heterogeneity. The probability of these two release types is presented as a function of the characteristics of WL heterogeneity and the slab. One of the main outcomes is that, for realistic values of the parameters, the tensile failure propensity is mainly influenced by slab properties. Hard and thick snow slabs are more prone to wide-scale crack propagation and thus lead to larger avalanches (full-slope release). In this case, the avalanche size is mainly influenced by topographical and morphological features such as rocks, trees, slope curvature and the spatial variability of the snow depth as often claimed in the literature.

  20. Closed-Loop Double Endobutton Technique for Repair of Unstable Distal Clavicle Fractures

    PubMed Central

    Struhl, Steven; Wolfson, Theodore S.

    2016-01-01

    Background: Displaced fractures of the distal clavicle are inherently unstable and lead to nonunion in a high percentage of cases. The optimal surgical management remains controversial. Hypothesis: Indirect osteosynthesis with a closed-loop double endobutton construct would result in reliable fracture union and obviate the need for additional surgery. Study Design: Case series; Level of evidence, 4. Methods: Eight patients with an acute unstable Neer type IIB distal clavicle fracture were treated with a closed-loop double endobutton implant. Mean follow-up averaged 3.4 years (range, 1-9 years). Two patients were lost to follow-up. The remaining 6 patients underwent a detailed functional and radiologic evaluation. Results: Definitive fracture healing was achieved in all patients. There were no complications, and no patients required additional surgery related to the index procedure. The mean Constant score was 97 at final follow-up. Conclusion: The closed-loop double endobutton technique was reliable and effective in achieving fracture union in all patients with unstable Neer type IIB fractures of the distal clavicle. This technique obviates the need for late hardware removal that is often necessary when direct osteosynthesis is used and avoids potential complications associated with coracoclavicular cerclage constructs that require knot fixation. PMID:27504466

  1. Effect of different veneering techniques on the fracture strength of metal and zirconia frameworks

    PubMed Central

    Turk, Ayse Gozde; Ulusoy, Mubin; Yuce, Mert

    2015-01-01

    PURPOSE To determine whether the fracture strengths and failure types differed between metal and zirconia frameworks veneered with pressable or layering ceramics. MATERIALS AND METHODS A phantom molar tooth was prepared and duplicated in 40 cobalt-chromium abutments. Twenty metal (IPS d.SIGN 15, Ivoclar, Vivadent, Schaan, Liechtenstein) and 20 zirconia (IPS e.max ZirCAD, Ivoclar) frameworks were fabricated on the abutments. Each framework group was randomly divided into 2 subgroups according to the veneering material: pressable and layering ceramics (n=10). Forty molar crowns were fabricated, cemented onto the corresponding abutments and then thermocycled (5-55℃, 10,000 cycles). A load was applied in a universal testing machine until a fracture occurred on the crowns. In addition, failure types were examined using a stereomicroscope. Fracture load data were analyzed using one-way ANOVA and Tukey HSD post-hoc tests at a significance level of 0.05. RESULTS The highest strength value was seen in metal-pressable (MP) group, whereas zirconia-pressable (ZP) group exhibited the lowest one. Moreover, group MP showed significantly higher fracture loads than group ZP (P=.015) and zirconia-layering (ZL) (P=.038) group. No significant difference in fracture strength was detected between groups MP and ML, and groups ZP and ZL (P>.05). Predominant fracture types were cohesive for metal groups and adhesive for zirconia groups. CONCLUSION Fracture strength of a restoration with a metal or a zirconia framework was independent of the veneering techniques. However, the pressing technique over metal frameworks resisted significantly higher fracture loads than zirconia frameworks. PMID:26816575

  2. Surgical Technique of Anterolateral Approach for Tibial Plateau Fracture.

    PubMed

    Wang, Peng-cheng; Ren, Dong; Zhou, Bing

    2015-11-01

    A 66-year-old woman had sustained crush injury 3 hours prior to her presentation to our hospital. The diagnosis was defined as lateral tibial plateau fracture of the right knee (Schatzker III). Supine position was set up and a pad was put under the affected hip. After sterilization of the surgical field the sterilized sheets were placed beneath the leg in order to be higher than the other side. A rolled sheet was put under the knee joint so that the knee joint was flexed around 30° to 40°. After the surgical field was draped the skin was incised. Iliotibial band was incised by blade (not by electrotomy) and sharp dissection was performed in the Gerdy's tubercle. Capsulotomy was made by cutting the tibial meniscal ligament. Then the meniscus was tagged superiorly and the articular surface was clearly visualized. A window was made in the lateral cortex beneath the plateau, so the impacted fragment was elevated through the window. The metaphyseal void was filled by bone allograft. The placement of the raft-screw plate must be ensured that the raft screws passing the plate could purchase the subchondral bone. After perfect placement of the plate was defined, the femoral distractor was removed and the knee joint was relaxed. It was ensured that the alignment of the lower leg was normal, and then the other screws were inserted. Following placing drainage in the wound the iliotibial band was closed and the subcutaneous soft tissue and skin were closed in layer. PMID:26791810

  3. Fractures

    PubMed Central

    Hall, Michael C.

    1963-01-01

    Recent studies on the epidemiology and repair of fractures are reviewed. The type and severity of the fracture bears a relation to the age, sex and occupation of the patient. Bone tissue after fracture shows a process of inflammation and repair common to all members of the connective tissue family, but it repairs with specific tissue. Cartilage forms when the oxygen supply is outgrown. After a fracture, the vascular bed enlarges. The major blood supply to healing tissue is from medullary vessels and destruction of them will cause necrosis of the inner two-thirds of the cortex. Callus rapidly mineralizes, but full mineralization is achieved slowly; increased mineral metabolism lasts several years after fracture. PMID:13952119

  4. Different surface preparation techniques of porcelain repaired with composite resin and fracture resistance

    PubMed Central

    Abd Wahab, Mohd Helmy Khalid; Bakar, Wan Zaripah Wan; Husein, Adam

    2011-01-01

    Background: Porcelain from prosthesis such as crown or bridge can be fractured if exposed to trauma; and, can be repaired at chairside using composite resin. Aim: To investigate the fracture resistance of few techniques of surface preparation in repairing fractured porcelain using composite resin. Materials and Methods: Eighty samples of porcelain blocks were divided into 4 groups for different surface preparations, such as, Cimara repairing kit; porcelain etch kit containing hydrofluoric acid; Panavia F resin cement; and, sandblasting using aluminium oxide, before composite resin (Filtek Z250, 3M ESPE) was bonded to the prepared porcelain blocks. Twenty others samples in the control group comprised of pure porcelain blocks. The fracture resistance of each sample was tested using Instron machine (UK). Results: With the exception of the group repaired using hydrofluoric acid (3.04±1.04 Mpa), all the other groups showed significant difference in the fracture resistance values when compared to the control group (3.05 ± 1.42 MPa) at P<0.05. Conclusions: Etching of the porcelain blocks with hydrofluoric acid holds promise in the repair of fractured porcelain with composite resin at chairside. PMID:22144809

  5. Novel intramedullary-fixation technique for long bone fragility fractures using bioresorbable materials.

    PubMed

    Nishizuka, Takanobu; Kurahashi, Toshikazu; Hara, Tatsuya; Hirata, Hitoshi; Kasuga, Toshihiro

    2014-01-01

    Almost all of the currently available fracture fixation devices for metaphyseal fragility fractures are made of hard metals, which carry a high risk of implant-related complications such as implant cutout in severely osteoporotic patients. We developed a novel fracture fixation technique (intramedullary-fixation with biodegradable materials; IM-BM) for severely weakened long bones using three different non-metallic biomaterials, a poly(l-lactide) (PLLA) woven tube, a nonwoven polyhydroxyalkanoates (PHA) fiber mat, and an injectable calcium phosphate cement (CPC). The purpose of this work was to evaluate the feasibility of IM-BM with mechanical testing as well as with an animal experiment. To perform mechanical testing, we fixed two longitudinal acrylic pipes with four different methods, and used them for a three-point bending test (N = 5). The three-point bending test revealed that the average fracture energy for the IM-BM group (PLLA + CPC + PHA) was 3 times greater than that of PLLA + CPC group, and 60 to 200 times greater than that of CPC + PHA group and CPC group. Using an osteoporotic rabbit distal femur incomplete fracture model, sixteen rabbits were randomly allocated into four experimental groups (IM-BM group, PLLA + CPC group, CPC group, Kirschner wire (K-wire) group). No rabbit in the IM-BM group suffered fracture displacement even under full weight bearing. In contrast, two rabbits in the PLLA + CPC group, three rabbits in the CPC group, and three rabbits in the K-wire group suffered fracture displacement within the first postoperative week. The present work demonstrated that IM-BM was strong enough to reinforce and stabilize incomplete fractures with both mechanical testing and an animal experiment even in the distal thigh, where bone is exposed to the highest bending and torsional stresses in the body. IM-BM can be one treatment option for those with severe osteoporosis. PMID:25111138

  6. Novel Intramedullary-Fixation Technique for Long Bone Fragility Fractures Using Bioresorbable Materials

    PubMed Central

    Nishizuka, Takanobu; Kurahashi, Toshikazu; Hara, Tatsuya; Hirata, Hitoshi; Kasuga, Toshihiro

    2014-01-01

    Almost all of the currently available fracture fixation devices for metaphyseal fragility fractures are made of hard metals, which carry a high risk of implant-related complications such as implant cutout in severely osteoporotic patients. We developed a novel fracture fixation technique (intramedullary-fixation with biodegradable materials; IM-BM) for severely weakened long bones using three different non-metallic biomaterials, a poly(l-lactide) (PLLA) woven tube, a nonwoven polyhydroxyalkanoates (PHA) fiber mat, and an injectable calcium phosphate cement (CPC). The purpose of this work was to evaluate the feasibility of IM-BM with mechanical testing as well as with an animal experiment. To perform mechanical testing, we fixed two longitudinal acrylic pipes with four different methods, and used them for a three-point bending test (N = 5). The three-point bending test revealed that the average fracture energy for the IM-BM group (PLLA + CPC + PHA) was 3 times greater than that of PLLA + CPC group, and 60 to 200 times greater than that of CPC + PHA group and CPC group. Using an osteoporotic rabbit distal femur incomplete fracture model, sixteen rabbits were randomly allocated into four experimental groups (IM-BM group, PLLA + CPC group, CPC group, Kirschner wire (K-wire) group). No rabbit in the IM-BM group suffered fracture displacement even under full weight bearing. In contrast, two rabbits in the PLLA + CPC group, three rabbits in the CPC group, and three rabbits in the K-wire group suffered fracture displacement within the first postoperative week. The present work demonstrated that IM-BM was strong enough to reinforce and stabilize incomplete fractures with both mechanical testing and an animal experiment even in the distal thigh, where bone is exposed to the highest bending and torsional stresses in the body. IM-BM can be one treatment option for those with severe osteoporosis. PMID:25111138

  7. Development of experimental verification techniques for non-linear deformation and fracture.

    SciTech Connect

    Moody, Neville Reid; Bahr, David F.

    2003-12-01

    This project covers three distinct features of thin film fracture and deformation in which the current experimental technique of nanoindentation demonstrates limitations. The first feature is film fracture, which can be generated either by nanoindentation or bulge testing thin films. Examples of both tests will be shown, in particular oxide films on metallic or semiconductor substrates. Nanoindentations were made into oxide films on aluminum and titanium substrates for two cases; one where the metal was a bulk (effectively single crystal) material and the other where the metal was a 1 pm thick film grown on a silica or silicon substrate. In both cases indentation was used to produce discontinuous loading curves, which indicate film fracture after plastic deformation of the metal. The oxides on bulk metals fractures occurred at reproducible loads, and the tensile stress in the films at fracture were approximately 10 and 15 GPa for the aluminum and titanium oxides respectively. Similarly, bulge tests of piezoelectric oxide films have been carried out and demonstrate film fracture at stresses of only 100's of MPa, suggesting the importance of defects and film thickness in evaluating film strength. The second feature of concern is film adhesion. Several qualitative and quantitative tests exist today that measure the adhesion properties of thin films. A relatively new technique that uses stressed overlayers to measure adhesion has been proposed and extensively studied. Delamination of thin films manifests itself in the form of either telephone cord or straight buckles. The buckles are used to calculate the interfacial fracture toughness of the film-substrate system. Nanoindentation can be utilized if more energy is needed to initiate buckling of the film system. Finally, deformation in metallic systems can lead to non-linear deformation due to 'bursts' of dislocation activity during nanoindentation. An experimental study to examine the structure of dislocations around

  8. Alternative electronic logging technique locates fractures in Austin chalk horizontal well

    SciTech Connect

    Stang, C.W. )

    1989-11-01

    This article describes the search for a technique to locate fractures in a horizontal well. The author focuses on the utilization of a formation microscanner (FMS). The FMS is described and the results and problems associated with its utilization are presented.

  9. Fractures

    MedlinePlus

    ... commonly happen because of car accidents, falls, or sports injuries. Other causes are low bone density and osteoporosis, which cause weakening of the bones. Overuse can cause stress fractures, which are very small cracks in the ...

  10. Pulse transient hot strip technique adapted for slab sample geometry to study anisotropic thermal transport properties of μm-thin crystalline films.

    PubMed

    Ma, Y; Gustavsson, J S; Haglund, A; Gustavsson, M; Gustafsson, S E

    2014-04-01

    A new method based on the adaptation of the Pulse Transient Hot Strip technique to slab sample geometry has been developed for studying thermal conductivity and thermal diffusivity of anisotropic thin film materials (<50 μm) with thermal conductivity in the 0.01-100 W/mK range, deposited on thin substrates (i.e., wafers). Strength of this technique is that it provides a well-controlled thermal probing depth, making it possible to probe a predetermined depth of the sample layer and thereby avoiding the influence from material(s) deeper down in the sample. To verify the technique a series of measurements were conducted on a y-cut single crystal quartz wafer. A Hot Strip sensor (32-μm wide, 3.2-mm long) was deposited along two orthogonal crystallographic (x- and z-) directions and two independent pulse transients were recorded. Thereafter, the data was fitted to our theoretical model, and the anisotropic thermal transport properties were determined. Using a thermal probing depth of only 30 μm, we obtained a thermal conductivity along the perpendicular (parallel) direction to the z-, i.e., optic axis of 6.48 (11.4) W/mK, and a thermal diffusivity of 3.62 (6.52) mm(2)/s. This yields a volumetric specific heat of 1.79 MJ/mK. These values agree well with tabulated data on bulk crystalline quartz supporting the accuracy of the technique, and the obtained standard deviation of less than 2.7% demonstrates the precision of this new measurement technique.

  11. A high yield technique for freeze-fracturing of small fractions of isolated cells.

    PubMed

    Falcieri, E; Mariani, A R; Del Coco, R; Facchini, A; Maraldi, N M

    1988-07-01

    A simple, high-yield technique for the freeze-fracturing of small amounts of isolated cells is described. A drop of cells fixed in suspension is deposited on a polylysine-treated coverslip, forming a monolayer through electrostatic forces. After cryoprotection, the coverslip is inverted on a gold carrier covered with Vinol and then frozen in liquid nitrogen. The monolayer will be fractured by advancing the knife under the coverslip. Large areas of cell surface can be exposed despite their low number, such as that obtainable after cell sorting by flow cytometry. PMID:3179998

  12. Fracture Resistance of Premolars Restored by Various Types and Placement Techniques of Resin Composites

    PubMed Central

    Moosavi, Horieh; Zeynali, Mahsa; Pour, Zahra Hosseini

    2012-01-01

    To verify the fracture resistance of premolars with mesioocclusodistal preparations restored by different resin composites and placement techniques. Sixty premolars were randomly divided into two groups based on type of composite resin: Filtek P60 or Nulite F, and then each group was separated into three subgroups: bulk, centripetal, and fiber insert according to the type of placement method (n = 10). Single-bond adhesive system was used as composite bonding according to the manufacturer's instructions. Specimens were restored in Groups 1, 2, and 3 with Filtek P60 and in Groups 4, 5, and 6 with Nulite F. After being stored 24 hours at 37°C, a 4 mm diameter steel sphere in a universal testing machine was applied on tooth buccal and lingual cusps at a cross-head speed of 5 mm/min until fracture occurred. Groups 3 and 6 showed higher fracture resistance than Groups 1, 2, 4, and 5. Among the placement techniques, the fiber insert method had a significant effect, but the type of composite was ineffective. The insertion technique in contrast to the type of material had a significant influence on the fracture resistance of premolar teeth. PMID:22666255

  13. Technique for reduction and percutaneous fixation of U- and H-shaped sacral fractures.

    PubMed

    Ruatti, S; Kerschbaumer, G; Gay, E; Milaire, M; Merloz, P; Tonetti, J

    2013-09-01

    We describe an early reduction and percutaneous fixation technique for isolated sacral fractures. Strong manual traction combined with manual counter-traction on the torso is used to disimpact the fracture. Transcondylar traction is then applied bilaterally and two ilio-sacral screws are inserted percutaneously on each side. Open reduction and fixation, with sacral laminectomy in patients with neurological abnormalities, remains the reference standard. Early reduction and percutaneous fixation ensures restoration of the pelvic parameters while minimising soft-tissue damage and the risk of infection. Decompression procedures can be performed either during the same surgical procedure after changing the installation or after a few days. These complex fractures warrant patient referral to specialised reference centres.

  14. Application of a new multiple fracturing technique to enhance gas production in Devonian shale

    SciTech Connect

    Cuderman, J.F.

    1984-01-01

    A new multiple fracturing technology has been applied in stimulating a Devonian shale gas well. In this new technique, propellants are used to obtain controlled pressurization of the wellbore to produce multiple fractures. The pressurization is controlled by suitable choice of propellants having different burn rates. The pressure risetime is the most important parameter governing fracture behavior. Methods are presented for specifying both the risetime and propellants to achieve it for Devonian shales. The Devonian shale stimulation was conducted in a 1040 m deep well in Meigs Co., Ohio. The experimental installation and hardware used are described together with results which include an increase in production from 190 m/sup 3//day to 623 m/sup 3//day. 7 references, 5 figures, 1 table.

  15. Development of experimental verification techniques for non-linear deformation and fracture on the nanometer scale.

    SciTech Connect

    Moody, Neville Reid; Bahr, David F.

    2005-11-01

    This work covers three distinct aspects of deformation and fracture during indentations. In particular, we develop an approach to verification of nanoindentation induced film fracture in hard film/soft substrate systems; we examine the ability to perform these experiments in harsh environments; we investigate the methods by which the resulting deformation from indentation can be quantified and correlated to computational simulations, and we examine the onset of plasticity during indentation testing. First, nanoindentation was utilized to induce fracture of brittle thin oxide films on compliant substrates. During the indentation, a load is applied and the penetration depth is continuously measured. A sudden discontinuity, indicative of film fracture, was observed upon the loading portion of the load-depth curve. The mechanical properties of thermally grown oxide films on various substrates were calculated using two different numerical methods. The first method utilized a plate bending approach by modeling the thin film as an axisymmetric circular plate on a compliant foundation. The second method measured the applied energy for fracture. The crack extension force and applied stress intensity at fracture was then determined from the energy measurements. Secondly, slip steps form on the free surface around indentations in most crystalline materials when dislocations reach the free surface. Analysis of these slip steps provides information about the deformation taking place in the material. Techniques have now been developed to allow for accurate and consistent measurement of slip steps and the effects of crystal orientation and tip geometry are characterized. These techniques will be described and compared to results from dislocation dynamics simulations.

  16. Minimally invasive reconstruction of lateral tibial plateau fractures using the jail technique: a biomechanical study

    PubMed Central

    2013-01-01

    Background This study described a novel, minimally invasive reconstruction technique of lateral tibial plateau fractures using a three-screw jail technique and compared it to a conventional two-screw osteosynthesis technique. The benefit of an additional screw implanted in the proximal tibia from the anterior at an angle of 90° below the conventional two-screw reconstruction after lateral tibial plateau fracture was evaluated. This new method was called the jail technique. Methods The two reconstruction techniques were tested using a porcine model (n = 40). Fracture was simulated using a defined osteotomy of the lateral tibial plateau. Load-to-failure and multiple cyclic loading tests were conducted using a material testing machine. Twenty tibias were used for each reconstruction technique, ten of which were loaded in a load-to-failure protocol and ten cyclically loaded (5000 times) between 200 and 1000 N using a ramp protocol. Displacement, stiffness and yield load were determined from the resulting load displacement curve. Failure was macroscopically documented. Results In the load-to-failure testing, the jail technique showed a significantly higher mean maximum load (2275.9 N) in comparison to the conventional reconstruction (1796.5 N, p < 0.001). The trend for better outcomes for the novel technique in terms of stiffness and yield load did not reach statistical significance (p > 0.05). In cyclic testing, the jail technique also showed better trends in displacement that were not statistically significant. Failure modes showed a tendency of screws cutting through the bone (cut-out) in the conventional reconstruction. No cut-out but a bending of the lag screws at the site of the additional third screw was observed in the jail technique. Conclusions The results of this study indicate that the jail and the conventional technique have seemingly similar biomechanical properties. This suggests that the jail technique may be a feasible alternative to

  17. Biomechanical Evaluation of a Mandibular Spanning Plate Technique Compared to Standard Plating Techniques to Treat Mandibular Symphyseal Fractures

    PubMed Central

    Richardson, Matthew; Hayes, Jonathan; Jordan, J. Randall; Puckett, Aaron; Fort, Matthew

    2015-01-01

    Purpose. The purpose of this study is to compare the biomechanical behavior of the spanning reconstruction plate compared to standard plating techniques for mandibular symphyseal fractures. Materials and Methods. Twenty-five human mandible replicas were used. Five unaltered synthetic mandibles were used as controls. Four experimental groups of different reconstruction techniques with five in each group were tested. Each synthetic mandible was subjected to a splaying force applied to the mandibular angle by a mechanical testing unit until the construct failed. Peak load and stiffness were recorded. The peak load and stiffness were analyzed using ANOVA and the Tukey test at a confidence level of 95% (P < 0.05). Results. The two parallel plates' group showed statistically significant lower values for peak load and stiffness compared to all other groups. No statistically significant difference was found for peak load and stiffness between the control (C) group, lag screw (LS) group, and the spanning plate (SP1) group. Conclusions. The spanning reconstruction plate technique for fixation of mandibular symphyseal fractures showed similar mechanical behavior to the lag screw technique when subjected to splaying forces between the mandibular gonial angles and may be considered as an alternative technique when increased reconstructive strength is needed. PMID:26649332

  18. Evaluation of geophysical techniques for identifying fractures in program wells in Deaf Smith County, Texas: Revision 1, Topical report

    SciTech Connect

    Gillespie, R.P.; Siminitz, P.C.

    1987-08-01

    Quantitative information about the presence and orientation of fractures is essential for the understanding of the geomechanical and geohydrological behavior of rocks. This report evaluates various borehole geophysical techniques for characterizing fractures in three Civilian Radioactive Waste Management (CRWM) Program test wells in the Palo Duro Basin in Deaf Smith County, Texas. Emphasis has been placed on the Schlumberger Fracture Identification Log (FIL) which detects vertical fractures and provides data for calculation of orientation. Depths of FIL anomalies were compared to available core. It was found that the application of FIL results to characterize fracture frequency or orientation is inappropriate at this time. The uncertainties associated with the FIL information render the information unreliable. No geophysical logging tool appears to unequivocally determine the location and orientation of fractures in a borehole. Geologic mapping of the exploratory shafts will ultimately provide the best data on fracture frequency and orientation at the proposed repository site. 22 refs., 6 figs., 3 tabs.

  19. Fracture of distal humerus: MIPO technique with visualization of the radial nerve

    PubMed Central

    Zogbi, Daniel Romano; Terrivel, Alberto Maranon; Mouraria, Guilherme Grisi; Mongon, Maurício Leal Dias; Kikuta, Fernando Kenji; Filho, Américo Zoppi

    2014-01-01

    OBJECTIVES: To evaluate the outcomes in patients treated for humerus distal third fractures with MIPO technique and visualization of the radial nerve by an accessory approach, in those without radial palsy before surgery. METHODS: The patients were treated with MIPO technique. The visualization and isolation of the radial nerve was done by an approach between the brachialis and the brachiorradialis, with an oblique incision, in the lateral side of the arm. MEPS was used to evaluate the elbow function. RESULTS: Seven patients were evaluated with a mean age of 29.8 years old. The average follow up was 29.85 months. The radial neuropraxis after surgery occurred in three patients. The sensorial recovery occurred after 3.16 months on average and also of the motor function, after 5.33 months on average, in all patients. We achieved fracture consolidation in all patients (M=4.22 months). The averages for flexion-extension and prono-supination were 112.85° and 145°, respectively. The MEPS average score was 86.42. There was no case of infection. CONCLUSION: This approach allowed excluding a radial nerve interposition on site of the fracture and/or under the plate, showing a high level of consolidation of the fracture and a good evolution of the range of movement of the elbow. Level of Evidence IV, Case Series PMID:25538474

  20. A Novel Technique for Closed Reduction and Fixation of Paediatric Calcaneal Fracture Dislocation Injuries

    PubMed Central

    Faroug, Radwane; Stirling, Paul; Ali, Farhan

    2013-01-01

    Paediatric calcaneal fractures are rare injuries usually managed conservatively or with open reduction and internal fixation (ORIF). Closed reduction was previously thought to be impossible, and very few cases are reported in the literature. We report a new technique for closed reduction using Ilizarov half-rings. We report successful closed reduction and screwless fixation of an extra-articular calcaneal fracture dislocation in a 7-year-old boy. Reduction was achieved using two Ilizarov half-ring frames arranged perpendicular to each other, enabling simultaneous application of longitudinal and rotational traction. Anatomical reduction was achieved with restored angles of Bohler and Gissane. Two K-wires were the definitive fixation. Bony union with good functional outcome and minimal pain was achieved at eight-weeks follow up. ORIF of calcaneal fractures provides good functional outcome but is associated with high rates of malunion and postoperative pain. Preservation of the unique soft tissue envelope surrounding the calcaneus reduces the risk of infection. Closed reduction prevents distortion of these tissues and may lead to faster healing and mobilisation. Closed reduction and screwless fixation of paediatric calcaneal fractures is an achievable management option. Our technique has preserved the soft tissue envelope surrounding the calcaneus, has avoided retained metalwork related complications, and has resulted in a good functional outcome. PMID:23819090

  1. Triangular Fixation Technique for Bicolumn Restoration in Treatment of Distal Humerus Intercondylar Fracture

    PubMed Central

    Kang, Seung-Hoon; Jeong, Min; Lim, Hae-Seong

    2016-01-01

    Background Distal humerus intercondylar fractures are intra-articular and comminuted fractures involving soft tissue injury. As distal humerus is triangle-shaped, parallel plating coupled with articular fixation would be suitable for bicolumn restoration in treatment of distal humerus intercondylar fracture. Methods This study included 38 patients (15 males and 23 females) who underwent olecranon osteotomy, open reduction and internal fixation with the triangle-shaped cannulated screw and parallel locking plates (triangular fixation technique). Functional results were assessed with the visual analog scale (VAS) scores, Mayo elbow performance (MEP) scores and Disabilities of the Arm, Shoulder and Hand (DASH) questionnaires. Anteroposterior and lateral elbow radiographs were assessed for reduction, alignment, fracture union, posttraumatic arthrosis, and heterotopic ossification, and computed tomography (CT) scans were used to obtain more accurate measurements of articular discrepancy. Results All fractures healed primarily with no loss of reduction. The mean VAS, MEP, and DASH scores of the affected elbow were not significantly different from those of the unaffected elbow (p = 0.140, p = 0.090, and p = 0.262, respectively). The mean degree of flexion was significantly lower in the affected elbow than in the unaffected elbow, but was still considered as functional (p = 0.001, > 100° in 33 of 38 patients). Two cases of articular step-offs (> 2 mm) were seen on follow-up CT scans, but not significantly higher in the affected elbow than in the unaffected elbow (p = 0.657). Binary logistic regression analysis revealed that only Association for Osteosynthesis (AO) type C3 fractures correlated with good/excellent functional outcome (p = 0.012). Complications occurred in 12 of the 38 patients, and the overall reoperation rate for complications was 10.5% (4 of 38 patients). Conclusions Triangular fixation technique for bicolumn restoration was an effective and reliable

  2. Mason type 3 radial head fractures: proposal of a synthesis technique using bioabsorbable thread

    PubMed Central

    SALVI, ANDREA EMILIO

    2016-01-01

    Multifragmentary fractures of the radial head (Mason type 3) are challenging for the surgeon. They are usually treated by means of complete removal of the injured head and sometimes by implantation of a metal prosthesis. Indeed, the bone fragments are often too small to allow stabilization through screws or even wires. The Author proposes an alternative technique, tested on a sawbone model, in which bioabsorbable thread is used, introduced in a figure-of-eight fashion. A review of the literature is provided.

  3. Cusp Fracture Resistance of Maxillary Premolars Restored with the Bonded Amalgam Technique Using Various Luting Agents

    PubMed Central

    Marchan, Shivaughn M.; Coldero, Larry; White, Daniel; Smith, William A. J.; Rafeek, Reisha N.

    2009-01-01

    Objective. This in vitro study uses measurements of fracture resistance to compare maxillary premolars restored with the bonded amalgam technique using a new resin luting cement, glass ionomer, and resin-modified glass ionomer as the bonding agents. Materials. Eighty-five sound maxillary premolars were selected and randomly assigned to one of five test groups of 17 teeth each. One group of intact teeth served as the control. The remaining groups were prepared to a standard cavity form relative to the dimensions of the overall tooth and restored with amalgam alone or a bonded amalgam using one of three luting agents: RelyX Arc (a new resin luting cement), RelyX luting (a resin-modified glass ionomer), or Ketac-Cem μ (a glass ionomer) as the bonding agents. Each tooth was then subjected to compressive testing until catastrophic failure occurred. The mean loads at failure of each group were statistically compared using ANOVA with a post hoc Bonferroni test. Results. It was found that regardless of the luting cement used for the amalgam bonding technique, there was little effect on the fracture resistance of teeth. Conclusion. Cusp fracture resistance of premolars prepared with conservative MOD cavity preparations is not improved by using an amalgam-bonding technique compared to similar cavities restored with amalgam alone. PMID:20339450

  4. Use of 2D and 3D Imaging Techniques to Understand Fracture Growth

    NASA Astrophysics Data System (ADS)

    Lockner, D. A.

    2004-05-01

    The monitoring of acoustic emissions (AE) is a valuable tool for studying the brittle fracture process in rock. With the improved characterization of transducer response, researchers are able to apply a broad spectrum of seismological techniques to AE catalogues collected in the laboratory; i.e., moment tensor analysis, Vp/Vs ratios, attenuation, event clustering statistics, Gutenberg-Richter b-value and aftershock analysis. Since AE occurs spontaneously as a result of unstable microcrack growth during rock deformation experiments, it provides a non-destructive method to observe damage accumulation. I will give examples of visualization techniques that have proven helpful in the analysis of fracture nucleation and growth based on 3D event locations in granite and sandstone samples. These techniques are useful in interpreting the development of complex fracture systems in lab samples. Complementary measurements of wave speed anisotropy and heterogeneity are used to infer both the development of damage zones and the rate of infiltration of water during fluid injection experiments. Finally, spatial clustering of AE events is evaluated in terms of the surface roughness of reactivated faults during triaxial deformation experiments.

  5. A Reduction Technique for a Depressed and Impacted Nasomaxillary Buttress Fracture.

    PubMed

    Hwang, Kun; Kim, Hyung Mook

    2016-09-01

    The aim of this study is to introduce an easy method of reducing the depressed and impacted segment in a nasomaxillary buttress fracture.Through the gingiva-labial vestibular incision, the fracture segments were exposed. A blunt end of the Cottle elevator was inserted to the cleft of the fracture segments. An upward and lateral force was applied until the impacted segment was released and reduced to its anatomical position. Then, the segments were fixed with a miniplate.Fifteen patients (12 males, 3 females, mean age: 34.5 ± 11.7 years) were operated on. In 14 patients, the fragments were reduced in the anatomical position and secondary surgery was not required. In 1 patient, however, the infraorbital rim could not be reduced enough through a gingival incision and a secondary surgery was performed to reduce the orbital rim.A blunt end of the Cottle elevator is shallow and long enough to be inserted into the cleft and strong enough to transfer the force to reduce it into its anatomical position. This reduction technique using a Cottle elevator is easy and can be used for reducing the depressed and impacted segment in nasomaxillary buttress fractures.

  6. A comparative study of fixation techniques for type II fractures of the odontoid process.

    PubMed

    Graziano, G; Jaggers, C; Lee, M; Lynch, W

    1993-12-01

    Primary screw fixation of a Type II odontoid fracture or non-union is an attractive alternative to posterior atlanto-axial arthrodesis in that normal cervical motion can be maintained. Eight cervical cadaver spines, ranging in age from 17-90 years, were used for study. Type II fractures of the dens were created using an osteotome. Simulated fractures were fixed using one or two 3.5-mm bone screws. After testing each screw fixation technique, the screws were removed and a posterior C1-C2 brooks sublaminar wiring was performed using four 18-gauge wires with wooden blocks to simulate bone graft. No significant differences were found between bending and torsional stiffnesses for the one-screw and two-screw specimens. No significant differences were found between one- and two-screw fixation when compared with primary C1-C2 wiring in torsion. One- or two-screw fixation was as stiff as primary C1-C2 wiring in bending. One or two screws offers similar stability for fixation for a dens fracture. One- and two-screw fixation is at least as stiff as primary C1-C2 wiring in torsion and one- or two-screw fixation is stiffer than primary C1-C2 wiring in bending. PMID:8303437

  7. A Reduction Technique for a Depressed and Impacted Nasomaxillary Buttress Fracture.

    PubMed

    Hwang, Kun; Kim, Hyung Mook

    2016-09-01

    The aim of this study is to introduce an easy method of reducing the depressed and impacted segment in a nasomaxillary buttress fracture.Through the gingiva-labial vestibular incision, the fracture segments were exposed. A blunt end of the Cottle elevator was inserted to the cleft of the fracture segments. An upward and lateral force was applied until the impacted segment was released and reduced to its anatomical position. Then, the segments were fixed with a miniplate.Fifteen patients (12 males, 3 females, mean age: 34.5 ± 11.7 years) were operated on. In 14 patients, the fragments were reduced in the anatomical position and secondary surgery was not required. In 1 patient, however, the infraorbital rim could not be reduced enough through a gingival incision and a secondary surgery was performed to reduce the orbital rim.A blunt end of the Cottle elevator is shallow and long enough to be inserted into the cleft and strong enough to transfer the force to reduce it into its anatomical position. This reduction technique using a Cottle elevator is easy and can be used for reducing the depressed and impacted segment in nasomaxillary buttress fractures. PMID:27428920

  8. Reverse shoulder arthroplasty for proximal humeral fractures: update on indications, technique, and results.

    PubMed

    Acevedo, Daniel C; Vanbeek, Corinne; Lazarus, Mark D; Williams, Gerald R; Abboud, Joseph A

    2014-02-01

    The introduction of the reverse shoulder arthroplasty has provided shoulder surgeons with more options for the treatment of complex proximal humeral fractures in the elderly. Early reported results suggest that the average functional outcome may be better than hemiarthroplasty in certain patients and specific clinical scenarios. In addition, these results seem to be reached more quickly with less dependence on rehabilitation. The reverse prosthesis may be particularly useful in patients aged older than 70 years, especially those with severely comminuted fractures in osteopenic bone. These factors likely have a negative impact on the results of hemiarthroplasty and internal fixation. Despite the potential benefits of reverse arthroplasty for fracture, there is a significant learning curve with the use of this prosthesis, and it has its own set of complications. The surgeon must show appropriate judgment when selecting a reverse arthroplasty in the setting of a proximal humeral fracture and, furthermore, be well acquainted with the surgical technique and prosthetic options at the time of surgery. Although the longevity of this prosthesis remains unknown, midterm outcomes are promising. PMID:24418780

  9. Inverse measurement of stiffness by the normalization technique for J-integral fracture toughness

    SciTech Connect

    Brown, Eric

    2012-06-07

    The single specimen normalization technique for J-integral fracture toughness has been successfully employed by several researchers to study the strongly non-linear fracture response of ductile semicrystalline polymers. As part of the normalization technique the load and the plastic component of displacement are normalized. The normalized data is then fit with a normalization function that approximates a power law for small displacements that are dominated by blunting and smoothly transitions to a linear relationship for large displacements that are dominated by stable crack extension. Particularly for very ductile polymers the compliance term used to determine the plastic displacement can dominate the solution and small errors in determining the elastic modulus can lead to large errors in the normalization or even make it ill-posed. This can be further complicated for polymers where the elastic modulus is strong strain rate dependent and simply using a 'quasistatic' modulus from a dogbone measurement may not equate to the dominant strain rate in the compact tension specimen. The current work proposes directly measuring the compliance of the compact tension specimen in the solution of J-integral fracture toughness and then solving for the elastic modulus. By comparison with a range of strain rate data the dominant strain rate can then be determined.

  10. A simple FEM-DEM technique for fracture prediction in materials and structures

    NASA Astrophysics Data System (ADS)

    Zárate, Francisco; Oñate, Eugenio

    2015-09-01

    This paper presents a new computational technique for predicting the onset and evolution of fracture in a continuum in a simple manner combining the finite element method (FEM) and the discrete element method (DEM). Onset of cracking at a point is governed by a simple damage model. Once a crack is detected at an element side in the FE mesh, discrete elements are generated at the nodes sharing the side and a simple DEM mechanism is considered to follow the evolution of the crack. The combination of the DEM with simple 3-noded linear triangular elements correctly captures the onset of fracture and its evolution, as shown in several examples of application in two and three dimensions.

  11. Technique for repair of fractures and separations involving the cartilaginous portions of the anterior chest wall.

    PubMed

    Bonne, Stephanie L; Turnbull, Isaiah R; Southard, Robert E

    2015-06-01

    Internal fixation of the ribs has been shown in numerous studies to decrease complications following traumatic rib fractures. Anterior injuries to the chest wall causing cartilaginous fractures, although rare, can cause significant disability and can lead to a variety of complications and, therefore, pose a unique clinical problem. Here, we report the surgical technique used for four patients with internal fixation of injuries to the cartilaginous portions of the chest wall treated at our center. All patients had excellent clinical outcomes and reported improvement in symptoms, with no associated complications. Patients who have injuries to the anterior portions of the chest wall should be considered for internal fixation of the chest wall when the injuries are severe and can lead to clinical disability. PMID:26033132

  12. Direct reduction technique for superomedial dome impaction in geriatric acetabular fractures.

    PubMed

    Laflamme, G-Yves; Hebert-Davies, Jonah

    2014-02-01

    The treatment of acetabular fractures in the elderly patients remains challenging. The "Gull Sign," which was recently described, was 100% predictive of failure of reduction and/or fixation. However, we believe that adequate reduction can be achieved and lead to good functional outcomes. Our technique differs from classic methods because it uses an anterior intrapelvic approach (the modified Stoppa) to obtain direct reduction of the impacted fragments. Access to the impacted superomedial dome is achieved by mobilizing the quadrilateral fragment, thus allowing direct visualization of the impacted articular surface. After reduction, definitive fixation is obtained with 3.5-mm cortical screws positioned in the subchondral bone directly over the Gull fragment. Our technique was performed in 9 patients, with a mean follow-up of 2.8 years. The quality of reduction was within 3 mm in 7 patients (78%). The overall conversion rate to total hip arthroplasty was 33%. All patients undergoing total hip arthroplasty either had initial malreduction or suffered an early loss of reduction. Other complications included 1 case of heterotopic ossification (Brooker type II) and 1 case of deep vein thrombosis. There were no infections. The average Harris Hip Score was 81. Good reduction of superior medial dome impaction can be obtained and maintained in the well-selected geriatric patient. We believe that, appropriately used, this direct reduction technique can be an important adjunct to surgeons dealing with this troublesome fracture.

  13. Mason type 3 radial head fractures: proposal of a synthesis technique using bioabsorbable thread

    PubMed Central

    SALVI, ANDREA EMILIO

    2016-01-01

    Multifragmentary fractures of the radial head (Mason type 3) are challenging for the surgeon. They are usually treated by means of complete removal of the injured head and sometimes by implantation of a metal prosthesis. Indeed, the bone fragments are often too small to allow stabilization through screws or even wires. The Author proposes an alternative technique, tested on a sawbone model, in which bioabsorbable thread is used, introduced in a figure-of-eight fashion. A review of the literature is provided. PMID:27602353

  14. Study of fracture mechanisms of short fiber reinforced AS composite by acoustic emission technique

    SciTech Connect

    Kida, Sotoaki; Suzuki, Megumu

    1995-11-01

    The fracture mechanisms of short fiber reinforced AS composites are studied by acoustic emission technique for examining the effects of fiber contents. The loads P{sub b} and P{sub c} which the damage mechanisms change are obtained at the inflection points of the total AE energy curve the energy gradient method. The damages are generated by fiber breaking at the load point of P{sub b} and P{sub c} in B material, and by the fiber breaking and the debonding between resin and fiber at the load points of P{sub b} and P{sub c} in C material.

  15. Miniarthrotomy assisted percutaneous screw fixation for displaced medial malleolus fractures – A novel technique

    PubMed Central

    Saini, Pramod; Aggrawal, Abhinav; Meena, Sanjay; Trikha, Vivek; Mittal, Samarth

    2014-01-01

    Aim To describe here a technique of miniarthrotomy assisted percutaneous screw insertion for displaced Herscovici type B and C medial malleolar fractures. Method Incision was made centred over the superomedial angle of the ankle mortise, about half a cm medial to tibialis anterior. Arthrotomy was done and reduction obtained. Percuntaneously, two 4 mm cancellous cannulated screws were inserted through medial malleolus. Results and conclusion This approach allows direct visualization of reduction, removal of entrapped soft tissue and preservation of saphenous vein and nerve. PMID:25983507

  16. Mason type 3 radial head fractures: proposal of a synthesis technique using bioabsorbable thread.

    PubMed

    Salvi, Andrea Emilio

    2016-01-01

    Multifragmentary fractures of the radial head (Mason type 3) are challenging for the surgeon. They are usually treated by means of complete removal of the injured head and sometimes by implantation of a metal prosthesis. Indeed, the bone fragments are often too small to allow stabilization through screws or even wires. The Author proposes an alternative technique, tested on a sawbone model, in which bioabsorbable thread is used, introduced in a figure-of-eight fashion. A review of the literature is provided. PMID:27602353

  17. Imaging Fracture Networks Using Angled Crosshole Seismic Logging and Change Detection Techniques

    NASA Astrophysics Data System (ADS)

    Knox, H. A.; Grubelich, M. C.; Preston, L. A.; Knox, J. M.; King, D. K.

    2015-12-01

    We present results from a SubTER funded series of cross borehole geophysical imaging efforts designed to characterize fracture zones generated with an alternative stimulation method, which is being developed for Enhanced Geothermal Systems (EGS). One important characteristic of this stimulation method is that each detonation will produce multiple fractures without damaging the wellbore. To date, we have collected six full data sets with ~30k source-receiver pairs each for the purposes of high-resolution cross borehole seismic tomographic imaging. The first set of data serves as the baseline measurement (i.e. un-stimulated), three sets evaluate material changes after fracture emplacement and/or enhancement, and two sets are used for evaluation of pick error and seismic velocity changes attributable to changing environmental factors (i.e. saturation due to rain/snowfall in the shallow subsurface). Each of the six datasets has been evaluated for data quality and first arrivals have been picked on nearly 200k waveforms in the target area. Each set of data is then inverted using a Vidale-Hole finite-difference 3-D eikonal solver in two ways: 1) allowing for iterative ray tracing and 2) with fixed ray paths determined from the test performed before the fracture stimulation of interest. Utilizing these two methods allows us to compare and contrast the results from two commonly used change detection techniques. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  18. Evaluation of occlusal fracture resistance of three different core materials using the Nayyar core technique

    PubMed Central

    Reddy, Satti Narayana; Harika, Kolli; Manjula, Shobha; Chandra, Pavani; Vengi, Lokesh; Koka, Krishna Mohan

    2016-01-01

    Aim: The aim and purpose of this study was to determine the occlusal fracture resistance of three core buildup materials using the Nayyar technique. Materials and Methods: Thirty human extracted maxillary premolars were used for the study. The test samples were decoronated till the cementoenamel junction (CEJ) and proper cleaning and shaping was done with protaper niti files till the F3. Corresponding f3 protaper(Dentysply)gutta pecha cones were selected and obturated. The gutta-percha was removed till the depth of 4 mm from the coronal orifice with Gates Glidden (GG) drills for all the samples; then the samples were randomly divided into three different groups. Group I was restored with universal composite Z350XT, group II was restored with light curable glass ionomer cement (GIC), and group III was restored with miracle mix. The coronal buildup was done using compound supported matrix. The fracture resistance strength of all the specimen groups was tested under a universal testing machine. Results: The data of the study were statistically analyzed by one-way analysis of variance (ANOVA) and Bonferroni's comparison test. Results of the study showed that group I that was restored with the universal composite Z350XT showed much higher fracture resistance strength compared to the other two groups. Statistically significant difference was noted between group I and group II and also between group I and group III. Conclusion: It can be concluded that the core buildup done with composite offered better occlusal fracture resistance strength compared to light curable GIC and miracle mix. PMID:27011931

  19. Risk of injury to vascular-nerve bundle after calcaneal fracture: comparison among three techniques

    PubMed Central

    Labronici, Pedro José; Reder, Vitor Rodrigues; de Araujo Marins Filho, Guilherme Ferreira; Pires, Robinson Esteves Santos; Fernandes, Hélio Jorge Alvachian; Mercadante, Marcelo Tomanik

    2016-01-01

    Objective To ascertain whether the number of screws or pins placed in the calcaneus might increase the risk of injury when three different techniques for treating calcaneal fractures. Method 126 radiographs of patients who suffered displaced calcaneal fractures were retrospectively analyzed. Three surgical techniques were analyzed on an interobserver basis: 31 radiographs of patients treated using plates that were not specific for the calcaneus, 48 using specific plates and 47 using an external fixator. The risk of injury to the anatomical structures in relation to each Kirschner wire or screw was determined using a graded system in accordance with the Licht classification. The total risk of injury to the anatomical structures through placement of more than one wire/screw was quantified using the additive law of probabilities for the product, for independent events. Results All of the models presented high explanatory power for the risk evaluated, since the coefficient of determination values (R2) were greater than 98.6 for all the models. Therefore, the set of variables studied explained more than 98.6% of the variations in the risks of injury to arteries, veins or nerves and can be classified as excellent models for prevention of injuries. Conclusion The risk of injury to arteries, veins or nerves is not defined by the total number of pins/screws. The region and the number of pins/screws in each region define and determine the best distribution of the risk. PMID:27069891

  20. A simple technique for measuring the fracture energy of lithiated thin-film silicon electrodes at various lithium concentrations

    NASA Astrophysics Data System (ADS)

    Choi, Yong Seok; Pharr, Matt; Oh, Kyu Hwan; Vlassak, Joost J.

    2015-10-01

    We have measured the fracture energy of lithiated silicon thin-film electrodes as a function of lithium concentration using a bending test. First, silicon thin-films on copper substrates were lithiated to various states of charge. Then, bending tests were performed by deforming the substrate to a pre-defined shape, producing a variation of the curvature along the length of the electrode. The bending tests allow determination of the critical strains at which cracks initiate in the lithiated silicon. Using the substrate curvature technique, we also measured the elastic moduli and the stresses that develop in the electrodes during electrochemical lithiation. From these measurements, the fracture energy was calculated as a function of lithium concentration using a finite element simulation of fracture of an elastic film on an elastic-plastic substrate. The fracture energy was determined to be Γ = 12.0 ± 3.0 J m-2 for amorphous silicon and Γ = 10.0 ± 3.6 J m-2 for Li3.28Si, with little variation in the fracture energy for intermediate Li concentrations. These results provide a guideline for the practical design of high-capacity lithium ion batteries to avoid fracture. The experimental technique described in this paper also provides a simple means of measuring the fracture energy of brittle thin-films.

  1. Fracture Detection in Alluvial Fan Deposits Using Near-Surface Seismic Reflection Techniques

    NASA Astrophysics Data System (ADS)

    Black, R. A.; Miller, B.

    2012-12-01

    In this study we document the observation of probable extensive shallow vertical fracture systems in unprocessed 2-D source gathers from near-surface seismic reflection surveys conducted over unconsolidated materials in alluvial fans environments. Mapping of fracture and fault systems within the sedimentary sections at hydrocarbon exploration scales has become common practice. This is due to the advent of post-stack attribute analysis of 3-D seismic images worldwide. However, examples of fracture detection and imaging in the near-surface are currently lacking in the literature. In addition, examples of fracture detection and mapping in the pre-stack domain are also lacking. In this study, unprocessed seismic source gathers from very high-resolution reflection surveys over alluvial fan deposits in tectonically active areas appear to display distinct patterns of amplitude drop off, geometrically similar to patterns expected for vertical fracture systems. The patterns can also be extracted by attribute analysis using techniques such as envelope and coherency analyses. Simple standard processing steps such as trace editing, muting, and bandpass filtering enhance interpretability. The patterns appear to be consistent and spatially fixed in the subsurface from source location to source location. These are observed in areas of obvious recent local large-scale fault movement. Examples are given from two areas, eastern Queen Valley in California and eastern Fish Lake Valley in Nevada. The stratigraphic and sedimentation patterns are quite complicated in both areas, and sediment characteristics vary considerably between sites. The surface sediments in the Queen Valley case are, in general, much coarser with many more boulder-sized clasts in the shallow subsurface. The seismic source consisted of a 30-06 rifle fired downhole at a depth of 0.5m. While the boulders interfered with seismic source operations, the record quality was excellent. The alluvial materials, especially

  2. Flexible Intramedullary Nailing of Pediatric Humeral Fractures: Indications, Techniques, and Tips.

    PubMed

    Kelly, Derek M

    2016-06-01

    Most proximal and diaphyseal pediatric humeral fractures can be treated successfully by closed means; however, certain patient factors or fracture characteristics may make surgical stabilization with flexible intramedullary nails (FIN) a better choice. Common indications for FIN of pediatric humeral fractures include unstable proximal-third fractures in children nearing skeletal maturity, unstable distal metaphyseal-diaphyseal junction fractures, shaft fractures in polytraumatized patients or patients with ipsilateral both-bone forearm fractures (floating elbow), and prophylactic stabilization of benign diaphyseal bone cysts or surgical stabilization of pathologic fractures. FIN can be safely inserted in an antegrade or retrograde manner depending on the fracture location and configuration. Careful dissection at the location of rod insertion can prevent iatrogenic nerve injuries. Rapid fracture union and return to full function can be expected in most cases. Implant prominence is the most common complication.

  3. Management of Multiple Mandibular Fractures in a Child with Osteogenesis Imperfecta Using Arch Bar Retained Thermoformed Splints: A Novel Technique.

    PubMed

    Nilesh, Kumar; Sawant, Ashwini; Taur, Swapnil; Parkar, M I

    2016-01-01

    Osteogenesis Imperfecta (OI) is a heterogeneous group of autosomal dominant and recessive inherited disorders of type I collagen metabolism. Clinical features of OI include multiple bone fractures, muscle weakness, joint laxity, skeletal deformities, blue sclerae, hearing loss, and dentinogenesis imperfecta. This report presents a challenging case of multiple mandibular fractures in a five years old child with OI, which was successfully treated with a new, minimally invasive technique of closed reduction with arch bar retained thermoformed splint.

  4. An in situ high voltage electron microscopy technique for the study of deformation and fracture: In multilayered materials

    SciTech Connect

    Wall, M.A.; Barbee, T.W. Jr.; Weihs, T.P.

    1995-04-14

    A novel, in situ, high voltage electron microscopy technique for the direct observation of the micromechanisms of tensile deformation and fracture in nanostructured materials is detailed. This technique is particularly well suited for the dynamic observations of deformation and fracture in multilayered materials. The success of this type of in situ technique is highly dependent upon unique specimen preparation procedures and sample design, the importance thereof will be discussed. The initial observations discussed here are expected to aid in the understanding of the mechanical behavior of this new class of atomically engineered materials.

  5. Biomechanical evaluation of four different posterior screw and rod fixation techniques for the treatment of the odontoid fractures

    PubMed Central

    Li, Lei; Liu, Wen-Fei; Jiang, Hong-Kun; Li, Yun-Peng

    2015-01-01

    Problems that screw cannot be inserted may occur in screw-rod fixation techniques such as Harms technique. We compared the biomechanical stability imparted to the C-2 vertebrae by four designed posterior screw and rod fixation techniques for the management of odontoid fractures. A three-dimensional finite element model of the odontoid fracture was established by subtracting several unit structures from the normal model from a healthy male volunteer. 4 different fixation techniques, shown as follows: ① C-1 lateral mass and C-2 pedicle screw fixation (Harms technique); ② C-1 lateral mass and unilateral C-2 pedicle screw fixation combined with ipsilateral laminar screw fixation; ③ Unilateral C-1lateral mass combined with ipsilateral C-1 posterior arch, and C-2 pedicle screw fixation; and ④ Unilateral C1 lateral mass screw connected with bilateral C2 pedicle screw fixation was performed on the odontoid fracture model. The model was validated for axial rotation, flexion, extension, lateral bending, and tension for 1.5 Nm. Changes in motion in flexion-extension, lateral bending, and axial rotation were calculated. The finite element model of the odontoid fracture was established in this paper. All of the four screw-rod techniques significantly decreased motion in flexion-extension, lateral bending, and axial rotation, as compared with the destabilized odontoid fracture complex (P<0.05). There was no statistically significant difference in stability among the four screw techniques. We concluded that the first three fixation techniques are recommended to be used as surgical intervention for odontoid fracture, while the last can be used as supplementary for the former three methods. PMID:26309508

  6. Plating osteosynthesis of mid-distal humeral shaft fractures: minimally invasive versus conventional open reduction technique

    PubMed Central

    Zeng, Bingfang; He, Xiaojian; Chen, Qi; Hu, Shundong

    2009-01-01

    Results of two methods, conventional open reduction–internal plating and minimally invasive plating osteosynthesis (MIPO), in the treatment of mid-distal humeral shaft fractures were compared. Thirty-three patients were retrospectively analysed and divided into two groups. Group A (n = 17) patients were treated by MIPO and group B (n = 16) by conventional plating. The mean operation time in group A was 92.35 ± 57.68 minutes and 103.12 ± 31.08 minutes in group B (P = 0.513). Iatrogenic radial nerve palsy in group A was 0% (0/17) and 31.3% in group B (5/16 (P = 0.012). The mean fracture union time in group A was 15.29 ± 4.01 weeks (range 8–24 weeks), and 21.25 ± 13.67 weeks (range 10–58 weeks) in group B (P = 0.095). The mean UCLA end-result score in group A was 34.76 ± 0.56 points (range 33–35), and 34.38 ± 1.41 points (range 30–35) in group B (P = 0.299). The mean MEPI in group A was 99.41 ± 2.43 points (range 90–100) and 99.69 ± 1.25 points (range 95–100) in group B (P = 0.687). When compared to the conventional plating techniques, MIPO offers advantages in terms of reduced incidence of iatrogenic radial nerve palsies and accelerated fracture union and a similar functional outcome with respect to shoulder and elbow function. PMID:19301000

  7. Review of techniques for monitoring the healing fracture of bones for implementation in an internally fixated pelvis.

    PubMed

    Wong, Lydia Chwang Yuh; Chiu, Wing Kong; Russ, Matthias; Liew, Susan

    2012-03-01

    Sacral fractures from high-impact trauma often cause instability in the pelvic ring structure. Treatment is by internal fixation which clamps the fractured edges together to promote healing. Healing could take up to 12 weeks whereby patients are bedridden to avoid hindrances to the fracture from movement or weight bearing activities. Immobility can lead to muscle degradation and longer periods of rehabilitation. The ability to determine the time at which the fracture is stable enough to allow partial weight-bearing is important to reduce hospitalisation time. This review looks into different techniques used for monitoring the fracture healing of bones which could lead to possible methods for in situ and non-invasive assessment of healing fracture in a fixated pelvis. Traditional techniques being used include radiology and CT scans but were found to be unreliable at times and very subjective in addition to being non in situ. Strain gauges have proven to be very effective for accurate assessment of fracture healing as well as stability for long bones with external fixators but may not be suitable for an internally fixated pelvis. Ultrasound provides in situ monitoring of stiffness recovery but only assesses local fracture sites close to the skin surface and has only been tested on long bones. Vibration analysis can detect non-uniform healing due to its assessment of the overall structure but may suffer from low signal-to-noise ratio due to damping. Impedance techniques have been used to assess properties of non-long bones but recent studies have only been conducted on non-biological materials and more research needs to be done before it can be applicable for monitoring healing in the fixated pelvis.

  8. A simple technique for double plating of extraarticular distal humeral shaft fractures.

    PubMed

    Sharaby, Mohamed; Elhawary, Ahmed

    2012-12-01

    Plate fixation of extraarticular distal humeral shaft fracture is often difficult. Traditional techniques do not allow for stable fixation. A single DCP plate may have inadequate purchase in the distal fragment. The use of large plates extending distally over the lateral supracondylar ridge is often associated with pain and sometimes interferes with elbow range of motion. In this study, 22 patients with extra articular distal humeral fractures were managed with dual plating using a paratricipital approach. The first plate--a narrow DCP--was fixed on the dorsal surface of the humerus. The second plate--a small 3.5 reconstruction plate--was fixed on the dorsolateral surface. Elbow motion was started immediately after surgery. The average follow-up duration was 25 months. The mean elbow flexion/extension are was 4 degrees to 138 degrees. Infection was reported in two cases and was managed successfully with conservative measures. Postoperative radial nerve contusion was reported in one case with complete resolution within 3 months.

  9. Callus Formation and Mineralization after Fracture with Different Fixation Techniques: Minimally Invasive Plate Osteosynthesis versus Open Reduction Internal Fixation.

    PubMed

    Xu, Haitao; Xue, Zichao; Ding, Haoliang; Qin, Hui; An, Zhiquan

    2015-01-01

    Minimally invasive plate osteosynthesis(MIPO) has been considered as an alternative for fracture treatment. Previous study has demonstrated that MIPO technique has the advantage of less soft tissue injury compared with open reduction internal fixation (ORIF). However, the comparison of callus formation and mineralization between two plate osteosynthesis methods remains unknown. In this experiment, ulna fracture model was established in 42 beagle dogs. The fractures underwent reduction and internal fixation with MIPO or ORIF. Sequential fluorescent labeling and radiographs were applied to determine new callus formation and mineralization in two groups after operation. At 4, 8 and 12 weeks postoperatively, the animals were selected to be sacrificed and the ulna specimens were analyzed by Micro-CT. The sections were also treated with Masson staining for histological evaluation. More callus formation was observed in MIPO group in early stage of fracture healing. The fracture union rate has no significant difference between two groups. The results indicate that excessive soft tissue stripping may impact early callus formation. As MIPO technique can effectively reduce soft tissue injury with little incision, it is considered to be a promising alternative for fracture fixation.

  10. Callus Formation and Mineralization after Fracture with Different Fixation Techniques: Minimally Invasive Plate Osteosynthesis versus Open Reduction Internal Fixation

    PubMed Central

    Ding, Haoliang; Qin, Hui; An, Zhiquan

    2015-01-01

    Minimally invasive plate osteosynthesis(MIPO) has been considered as an alternative for fracture treatment. Previous study has demonstrated that MIPO technique has the advantage of less soft tissue injury compared with open reduction internal fixation (ORIF). However, the comparison of callus formation and mineralization between two plate osteosynthesis methods remains unknown. In this experiment, ulna fracture model was established in 42 beagle dogs. The fractures underwent reduction and internal fixation with MIPO or ORIF. Sequential fluorescent labeling and radiographs were applied to determine new callus formation and mineralization in two groups after operation. At 4, 8 and 12 weeks postoperatively, the animals were selected to be sacrificed and the ulna specimens were analyzed by Micro-CT. The sections were also treated with Masson staining for histological evaluation. More callus formation was observed in MIPO group in early stage of fracture healing. The fracture union rate has no significant difference between two groups. The results indicate that excessive soft tissue stripping may impact early callus formation. As MIPO technique can effectively reduce soft tissue injury with little incision, it is considered to be a promising alternative for fracture fixation. PMID:26444295

  11. A simple new technique for the removal of fractured femoral stems: a case report

    PubMed Central

    2014-01-01

    Introduction The removal of broken femoral stems has become a major issue in revision surgery, and is a technically difficult and time-consuming procedure. Case presentation We present a case of a fracture of a cementless long femoral stem in a 65-year-old, white Caucasian man. The distal part was removed with a special longitudinal osteotomy through the anterior cortex extending distally for 10cm. It was then followed by a transversal osteotomy 2cm below the tip of the femoral stump to allow enough space for two locking pliers. Simultaneously using a lamina spreader on the distal part, the broken stem was extracted while hammering on two locking pliers. Conclusions We developed a simple and easy technique for the removal of a broken femoral stem that can be applied to all kinds of femoral stems and intramedullary nails regardless of their cross section. We used ordinary surgical instruments and spared the remaining bone stock. PMID:24886067

  12. Multiscale organization of joints and faults in a fractured reservoir revealed by geostatistical, multifractal and wavelet techniques

    SciTech Connect

    Castaing, C.; Genter, A.; Ouillon, G.

    1995-08-01

    Datasets of the geometry of fracture systems were analysed at various scales in the western Arabian sedimentary platform by means of geostatistical, multifractal, and anisotropic-wavelet techniques. The investigations covered a wide range of scales, from regional to outcrops in a well-exposed area, and were based on field mapping of fractures, and the interpretation and digitizing of fracture patterns on aerial photographs and satellite images. As a first step, fracture data sets were used to examine the direction, size, spacing and density systematics, and the variability in these quantities with space and scale. Secondly, a multifractal analysis was carried out, which consists in estimating the moments of the spatial distribution of fractures at different resolutions. This global multifractal method was complemented by a local wavelet analysis, using a new anisotropic technique tailored to linear structures. For a map with a given scale of detail, this procedure permits to define integrated fracture patterns and their associated directions at a more regional scale. The main result of this combined approach is that fracturing is not a self-similar process from the centimeter scale up to the one-million-kilometer scale. Spatial distribution of faults appears as being highly controlled by the thickness of the different rheological layers that constitute the crust. A proceeding for upscaling fracture systems in sedimentary reservoirs can be proposed, based on (i) a power law for joint-length distribution, (ii) characteristic joint spacing depending on the critical sedimentary units, and (iii) fractal fault geometry for faults larger than the whole thickness of the sedimentary basin.

  13. How to measure slab-off and reverse slab prism in spectacle lenses.

    PubMed

    Christoff, Alexander; Guyton, David L

    2007-08-01

    It is well known that new spectacle lenses for the correction of anisometropia can induce diplopia with reading. The difference in the powers of the lenses induces a net prismatic effect that can cause double vision through off-center areas of the lenses. This is particularly bothersome when patients try to read, often noting vertical double vision in attempted downgaze, especially through multifocal add segments. This induced prismatic effect can be compensated at one level of downgaze by the use of slab-off or reverse slab prism. Typically the slab-off correction is ground into the stronger minus, or weaker plus lens. Reverse slab is ground into the weaker minus, or stronger plus, lens. Unfortunately, determining the amount of slab-off prism already incorporated into spectacle lenses is nonintuitive and inconvenient. This usually requires the use of a lens clock, which is not widely accessible to many ophthalmology practices. A simple technique, described in the past but poorly known, is illustrated here for quickly measuring slab-off and reverse slab prism prescription lenses in the clinic with a common manual lens meter.

  14. Cardiopulmonary resuscitation (CPR)-related posterior rib fractures in neonates and infants following recommended changes in CPR techniques.

    PubMed

    Franke, I; Pingen, A; Schiffmann, H; Vogel, M; Vlajnic, D; Ganschow, R; Born, M

    2014-07-01

    Posterior rib fractures are highly indicative of non-accidental trauma (NAT) in infants. Since 2000, the "two-thumbs" technique for cardiopulmonary resuscitation (CPR) of newborns and infants has been recommended by the American Heart Association (AHA). This technique is similar to the grip on an infant's thorax while shaking. Is it possible that posterior rib fractures in newborns and infants could be caused by the "two-thumbs" technique? Using computerized databases from three German children's hospitals, we identified all infants less than 12 months old who underwent professional CPR within a 10-year period. We included all infants with anterior-posterior chest radiographs taken after CPR. Exclusion criteria were sternotomy, osteopenia, various other bone diseases and NAT. The radiographs were independently reviewed by the Chief of Pediatric Radiology (MB) and a Senior Pediatrician, Head of the local Child Protection Team (IF). Eighty infants with 546 chest radiographs were identified, and 50 of those infants underwent CPR immediately after birth. Data concerning the length of CPR was available for 41 infants. The mean length of CPR was 11min (range: 1-180min, median: 3min). On average, there were seven radiographs per infant. A total of 39 infants had a follow-up radiograph after at least 10 days. No rib fracture was visible on any chest X-ray. The results of this study suggest rib fracture after the use of the "two-thumbs" CPR technique is uncommon. Thus, there should be careful consideration of abuse when these fractures are identified, regardless of whether CPR was performed and what technique used. The discovery of rib fractures in an infant who has undergone CPR without underlying bone disease or major trauma warrants a full child protection investigation. PMID:24636360

  15. Cardiopulmonary resuscitation (CPR)-related posterior rib fractures in neonates and infants following recommended changes in CPR techniques.

    PubMed

    Franke, I; Pingen, A; Schiffmann, H; Vogel, M; Vlajnic, D; Ganschow, R; Born, M

    2014-07-01

    Posterior rib fractures are highly indicative of non-accidental trauma (NAT) in infants. Since 2000, the "two-thumbs" technique for cardiopulmonary resuscitation (CPR) of newborns and infants has been recommended by the American Heart Association (AHA). This technique is similar to the grip on an infant's thorax while shaking. Is it possible that posterior rib fractures in newborns and infants could be caused by the "two-thumbs" technique? Using computerized databases from three German children's hospitals, we identified all infants less than 12 months old who underwent professional CPR within a 10-year period. We included all infants with anterior-posterior chest radiographs taken after CPR. Exclusion criteria were sternotomy, osteopenia, various other bone diseases and NAT. The radiographs were independently reviewed by the Chief of Pediatric Radiology (MB) and a Senior Pediatrician, Head of the local Child Protection Team (IF). Eighty infants with 546 chest radiographs were identified, and 50 of those infants underwent CPR immediately after birth. Data concerning the length of CPR was available for 41 infants. The mean length of CPR was 11min (range: 1-180min, median: 3min). On average, there were seven radiographs per infant. A total of 39 infants had a follow-up radiograph after at least 10 days. No rib fracture was visible on any chest X-ray. The results of this study suggest rib fracture after the use of the "two-thumbs" CPR technique is uncommon. Thus, there should be careful consideration of abuse when these fractures are identified, regardless of whether CPR was performed and what technique used. The discovery of rib fractures in an infant who has undergone CPR without underlying bone disease or major trauma warrants a full child protection investigation.

  16. A Fluoroscopy-Free Technique for Percutaneous Screw Positioning During Arthroscopic Treatment of Depression Tibial Plateau Fractures.

    PubMed

    Thaunat, Mathieu; Camelo Barbosa, Nuno; Tuteja, Sanesh; Jan, Nicolas; Fayard, Jean Marie; Sonnery-Cottet, Bertrand

    2016-06-01

    This article aims to describe a simple and reliable technique that helps in positioning the cannulated percutaneous screws during fixation of depression-type tibial plateau fractures. After fracture reduction under arthroscopic control, an outside-in anterior cruciate ligament femoral guide is introduced through the tibial cortical metaphyseal window and positioned under endoscopic control just underneath the elevated fragment. When proper height is achieved, a guide pin is drilled from lateral to medial through the sleeve, 1 to 2 cm distal to the articular surface of the depressed fragment. The cannulated screw can then be introduced under endoscopic control, without fluoroscopic assistance, just under the previously elevated joint surface. This technique ensures optimal placement of the cannulated screw in the middle of the bony tunnel to obtain optimal subchondral bone support during fixation of the depressed tibial plateau fracture. PMID:27656370

  17. Investigation of temperature dependence of fracture toughness in high-dose HT9 steel using small-specimen reuse technique

    SciTech Connect

    Baek, Jong-Hyuk; Byun, Thak Sang; Maloy, Stuart A.; Toloczko, Mychailo B.

    2014-01-01

    The temperature dependence of fracture toughness in HT9 steel irradiated to 3–145 dpa at 380–503 degrees*C was investigated using miniature three-point bend (TPB) fracture specimens. A miniature-specimen reuse technique has been established: the tested halves of subsize Charpy impact specimens with dimensions of 27 mm *3mm* 4 mm were reused for this fracture test campaign by cutting a notch with a diamond-saw in the middle of each half, and by fatigue-precracking to generate a sharp crack tip. It was confirmed that the fracture toughness of HT9 steel in the dose range depends more strongly on the irradiation temperature than the irradiation dose. At an irradiation temperature <430 *degreesC, the fracture toughness of irradiated HT9 increased with the test temperature, reached an upper shelf of 180—200 MPa*m^.5 at 350–450 degrees*C, and then decreased with the test temperature. At an irradiation temperature >430 degrees*C, the fracture toughness was nearly unchanged up to about 450 *degreesC and decreased slowly with test temperatures in a higher temperature range. Such a rather monotonic test temperature dependence after high-temperature irradiation is similar to that observed for an archive material generally showing a higher degree of toughness. A brittle fracture without stable crack growth occurred in only a few specimens with relatively lower irradiation and test temperatures. In this discussion, these TPB fracture toughness data are compared with previously published data from 12.7 mm diameter disc compact tension (DCT) specimens.

  18. Investigation of temperature dependence of fracture toughness in high-dose HT9 steel using small-specimen reuse technique

    SciTech Connect

    Baek, Jong-Hyuk; Byun, Thak Sang; Maloy, S; Toloczko, M

    2014-01-01

    The temperature dependence of fracture toughness in HT9 steel irradiated to 3 145 dpa at 380 503 C was investigated using miniature three-point bend (TPB) fracture specimens. A miniature-specimen reuse technique has been established: the tested halves of subsize Charpy impact specimens with dimensions of 27 mm 3mm 4 mm were reused for this fracture test campaign by cutting a notch with a diamond-saw in the middle of each half, and by fatigue-precracking to generate a sharp crack tip. It was confirmed that the fracture toughness of HT9 steel in the dose range depends more strongly on the irradiation temperature than the irradiation dose. At an irradiation temperature <430 C, the fracture toughness of irradiated HT9 increased with the test temperature, reached an upper shelf of 180 200 MPa ffiffiffiffiffi m p at 350 450 C, and then decreased with the test temperature. At an irradiation temperatureP430 C, the fracture toughness was nearly unchanged up to about 450 C and decreased slowly with test temperatures in a higher temperature range. Such a rather monotonic test temperature dependence after high-temperature irradiation is similar to that observed for an archive material generally showing a higher degree of toughness. A brittle fracture without stable crack growth occurred in only a few specimens with relatively lower irradiation and test temperatures. In this discussion, these TPB fracture toughness data are compared with previously published data from 12.7 mm diameter disc compact tension (DCT) specimens.

  19. An Effective and Feasible Method, “Hammering Technique,” for Percutaneous Fixation of Anterior Column Acetabular Fracture

    PubMed Central

    Zhang, Lihai; Zhang, Wei; Li, Tongtong; Li, Jiantao; Chen, Hua

    2016-01-01

    Objective. The objective of this study was to evaluate the effectiveness and advantages of percutaneous fixation of anterior column acetabular fracture with “hammering technique.” Materials and Methods. We retrospectively reviewed 16 patients with percutaneous fixation of anterior column acetabular fracture with “hammering technique.” There were 11 males and 5 females with an average age of 38.88 years (range: 24–54 years) in our study. Our study included 7 nondisplaced fractures, 6 mild displaced fractures (<2 mm), and 5 displaced fractures (>2 mm). The mean time from injury to surgery was 4.5 days (range: 2–7 days). Results. The average of operation time was 27.56 minutes (range: 15–45 minutes), and the mean blood loss was 55.28 mL (range: 15–100 mL). The mean fluoroscopic time was 54.78 seconds (range: 40–77 seconds). The first pass of the guide wire was acceptable without cortical perforation or intra-articular perforation in 88.89% (16/18) of the procedures, and the second attempt was in 11.11% (2/18). Conclusion. Our study suggested that percutaneous fixation of anterior column acetabular fracture with “hammering technique” acquired satisfying surgical and clinical outcomes. It may be an alternative satisfying treatment for percutaneous fixation of anterior column acetabular fracture by 2D fluoroscopy using a C-arm with less fluoroscopic time. PMID:27493962

  20. Fracture density in the deep subsurface: Techniques with application to Point Arguello oil field

    SciTech Connect

    Narr, W. )

    1991-08-01

    Because Monterey Formation reservoirs rely on fractures (joints) for permeability, quantitative information on fracture spacing is important to exploration strategies and for understanding reservoir behavior. Density of joints in cores of four wells from the Point Arguello reservoir has been determined with a new, probability-based method, and these subsurface joint densities are compared with joint densities is the fracture-spacing index, which is the slope of the trend of layer thickness to joint spacing. In core and at outcrop, the only lithologic control on joint density is between nonjointed mudstone and harder (more brittle), jointed rocks. Within each well, the fracture-spacing index is the same for all hard rocks (though it varies between wells). In the reservoir, joint density relates to structural position. At outcrops in various structural settings, the fracture-spacing index is the same (approximately 1.29) in chert, dolostone, and porcelanite and siliceous shale. These rocks may be saturated with joints, so that differences in brittle strain due to local structural variations have been overwhelmed as joints continued to form during unroofing of these strata. Chert looks more fractured than other lithologies because of thin bedding. Fracture-spacing index is used to compute such parameters as fracture porosity and volume of fractures that directly contact the well bore. These parameters may be important when trying to model the behavior of a petroleum reservoir, or when trying to assess the feasibility of strongly deviating wells to improve the performance of a fracture reservoir.

  1. Facial fractures.

    PubMed Central

    Carr, M. M.; Freiberg, A.; Martin, R. D.

    1994-01-01

    Emergency room physicians frequently see facial fractures that can have serious consequences for patients if mismanaged. This article reviews the signs, symptoms, imaging techniques, and general modes of treatment of common facial fractures. It focuses on fractures of the mandible, zygomaticomaxillary region, orbital floor, and nose. Images p520-a p522-a PMID:8199509

  2. Slab Leaf Bowls

    ERIC Educational Resources Information Center

    Suitor, Cheryl

    2012-01-01

    In science class, fourth graders investigate the structure of plants and leaves from trees and how the process of photosynthesis turns sunlight into sugar proteins. In this article, the author fuses art and science for a creative and successful clay slab project in her elementary art classroom. (Contains 1 online resource.)

  3. Development of Reservoir Characterization Techniques and Production Models for Exploiting Naturally Fractured Reservoirs

    SciTech Connect

    Wiggins, M.L.; Evans, R.D.; Brown, R.L.; Gupta, A.

    2001-03-28

    This report focuses on integrating geoscience and engineering data to develop a consistent characterization of the naturally fractured reservoirs. During this reporting period, effort was focused on relating seismic data to reservoir properties of naturally fractured reservoirs, scaling well log data to generate interwell descriptors of these reservoirs, enhancing and debugging a naturally fractured reservoir simulator, and developing a horizontal wellbore model for use in the simulator.

  4. Development of Reservoir Characterization Techniques and Production Models for Exploiting Naturally Fractured Reservoirs

    SciTech Connect

    Wiggins, Michael L; Brown, Raymon L.; Civan, Faruk; Hughes, Richard G.

    2002-10-08

    During this reporting period, research was continued on characterizing and modeling the behavior of naturally fractured reservoir systems. This report proposed a model to relate the seismic response to production data to determine crack spacing and aperture, provided details of tests of proposed models to obtain fracture properties from conventional well logs with actual field data, and verification of the naturally fractured reservoir simulator developed in this project.

  5. Slab melting versus slab dehydration in subduction-zone magmatism

    PubMed Central

    Mibe, Kenji; Kawamoto, Tatsuhiko; Matsukage, Kyoko N.; Fei, Yingwei; Ono, Shigeaki

    2011-01-01

    The second critical endpoint in the basalt-H2O system was directly determined by a high-pressure and high-temperature X-ray radiography technique. We found that the second critical endpoint occurs at around 3.4 GPa and 770 °C (corresponding to a depth of approximately 100 km in a subducting slab), which is much shallower than the previously estimated conditions. Our results indicate that the melting temperature of the subducting oceanic crust can no longer be defined beyond this critical condition and that the fluid released from subducting oceanic crust at depths greater than 100 km under volcanic arcs is supercritical fluid rather than aqueous fluid and/or hydrous melts. The position of the second critical endpoint explains why there is a limitation to the slab depth at which adakitic magmas are produced, as well as the origin of across-arc geochemical variations of trace elements in volcanic rocks in subduction zones. PMID:21536910

  6. Technique of Open Reduction and Internal Fixation of Comminuted Proximal Humerus Fractures With Allograft Femoral Head Metaphyseal Reconstruction.

    PubMed

    Parada, Stephen A; Makani, Amun; Stadecker, Monica J; Warner, Jon J P

    2015-10-01

    Proximal humerus fractures are common injuries that can require operative treatment. Different operative techniques are available, but the hallmark of fixation for 3- and 4-part fractures is a locking-plate-and-screw construct. Despite advances in this technology, obtaining anatomical reduction and fracture union can be difficult, and complications (eg, need for revision) are not uncommon. These issues can be addressed by augmenting the fixation with an endosteally placed fibular allograft. Although biomechanical and clinical results have been good, the technique can lead to difficulties in future revision to arthroplasty, a common consequence of failed open reduction and internal fixation. The technique described, an alternative to placing a long endosteal bone graft, uses a trapezoidal, individually sized pedestal of allograft femoral head to facilitate the reduction and healing of the humeral head and tuberosity fragments in a displaced 3- or 4-part fracture of the proximal humerus. It can be easily incorporated with any plate-and-screw construct and does not necessitate placing more than 1 cm of bone into the humeral intramedullary canal, limiting the negative effects on any future revision to arthroplasty.

  7. Least Possible Fixation Techniques of 4-Part Valgus Impacted Fractures of the Proximal Humerus: A Systematic Review

    PubMed Central

    Panagopoulos, Andreas; Tatani, Irini; Ntourantonis, Dimitrios; Seferlis, Ioannis; Kouzelis, Antonis; Tyllianakis, Minos

    2016-01-01

    The valgus-impacted (VI) 4-part fractures are a subset of fractures of the proximal humerus with a unique anatomic configuration characterized by a relatively lower incidence of avascular necrosis after operative intervention. We systematically reviewed clinical studies assessing the benefits and harms of least possible fixation techniques (LPFT) for this unique fracture type. Such information would be potentially helpful in developing an evidence-based approach in the management of these complex injuries. We performed analytic searches of PubMed, Embase, Web of Science, Google Scholar and the Cochrane Library, restricting it to the years 1991-2014. Included studies had to describe outcomes and complications after primary osteosynthesis with any type of LPFT apart from plate-screws and intramedullary nailing. Eligibility criteria were also included English language, more than 5 cases, minimum follow up of one year and report of clinical outcome using at least one relevant score (Constant, Neer or ASES). Based on 292 database hits we identified 12 eligible studies including 190 four-part valgus impacted fractures in 188 patients. All eligible studies were case series composed of min 8 to max 45 patients per study. The gender distribution was 60% (112) female and 40% (76) male. The average age of the patients at the time of injury was 54.5 years. In 8/12 studies an open reduction was used for fracture fixation using different surgical techniques including KW, cerclage wires, cannulated screws and osteosutures. Closed reduction and percutaneous fixation was used in 4 studies. Mean follow-up time ranged from 24 to 69 months. A good functional outcome (constant score >80) was reported in 9/12 studies. The most common complication was avascular necrosis of the humeral head with an overall incidence of 11% (range, 0-26.3%). Total avascular necrosis (AVN) was found in 15/188 patients (7.9%) and was more common in percutaneous techniques and partial AVN in 6/188 (3

  8. Modified Labial Button Technique for Maintaining Occlusion After Caudal Mandibular Fracture/Temporomandibular Joint Luxation in the Cat.

    PubMed

    Goodman, Alice E; Carmichael, Daniel T

    2016-03-01

    Maxillofacial trauma in cats often results in mandibular symphyseal separation in addition to injuries of the caudal mandible and/or temporomandibular joint (TMJ). Caudal mandibular and TMJ injuries are difficult to access and stabilize using direct fixation techniques, thus indirect fixation is commonly employed. The immediate goals of fixation include stabilization for return to normal occlusion and function with the long-term objective of bony union. Indirect fixation techniques commonly used for stabilization of caudal mandibular and temporomandibular joint fracture/luxation include maxillomandibular fixation (MMF) with acrylic composite, interarcade wiring, tape muzzles, and the bignathic encircling and retaining device (BEARD) technique. This article introduces a modification of the previously described "labial reverse suture through buttons" technique used by Koestlin et al and the "labial locking with buttons" technique by Rocha et al. In cases with minimally displaced subcondylar and pericondylar fractures without joint involvement, the labial button technique can provide sufficient stabilization for healing. Advantages of the modified labial button technique include ease of application, noninvasive nature, and use of readily available materials. The construct can remain in place for a variable of amount of time, depending on its intended purpose. It serves as an alternative to the tape muzzle, which is rarely tolerated by cats. This technique can be easily used in conjunction with other maxillomandibular repairs, such as cerclage wire fixation of mandibular symphyseal separation. The purpose of this article is to demonstrate a modified labial button technique for maintaining occlusion of feline caudal mandibular fractures/TMJ luxations in a step-by-step fashion. PMID:27487655

  9. A Novel Two-Step Technique for Retrieving Fractured Peripherally Inserted Central Catheter Segments Migrating into the Heart or the Pulmonary Artery

    PubMed Central

    Peng, Juan; Zhang, Xiao-Ming; Xu, Hao; Miao, Nan-Dong; Ren, Yong-Jun; Liu, Kang; Min, Xu-Li; Yang, Ke; Yang, Shi; Yang, Cheng

    2016-01-01

    Objective. To report the experience of a percutaneous technique for retrieving fractured peripherally inserted central catheter (PICC) segments migrating into the heart or the pulmonary artery. Method. From April 2013 to July 2015, we performed percutaneous retrieval of fractured PICC segments migrating into the heart or the pulmonary artery in five cancer patients who had undergone chemotherapy via PICC. The fractures were diagnosed with chest plain radiography. The patients included three cases of breast cancer, one case of rectal cancer, and one case of lower limb Ewing's tumor. The fractures were retained in the vessels of the patients for 1 to 3 days. All the fractures were retrieved by using a novel two-step technique in the digital subtraction angiography (DSA) suite. This two-step technique involves inserting a pigtail catheter to the heart or the pulmonary artery to grasp the fractured catheter fragment and bring it to the lower segment of the inferior vena cava, followed by grasping and removing the catheter fragment with a retrieval loop system of the vena cava filter retrieval set. Result. The fractured PICC segments were removed successfully in all five patients via unilateral (four patients) or bilateral (one patient) femoral vein access. No complications occurred during the interventional procedure. Conclusion. Percutaneous retrieval can be a safe, convenient, and minimally invasive method for the removal of fractured PICC segments. The technique reported in this paper will be applicable for the retrieval of fractured PICC segments and other catheter fragments migrating into the heart or the pulmonary artery.

  10. Preliminary results from osteosynthesis using Ender nails by means of a percutaneous technique, in humeral diaphysis fractures in adults☆

    PubMed Central

    Godinho, Glaydson Gomes; França, Flávio de Oliveira; Freitas, José Márcio Alves; Santos, Flávio Márcio Lago; Correa, Guilherme de Almeida Sellos; Maia, Lucas Russo

    2015-01-01

    Objective To demonstrate the clinical and functional results from treatment of humeral diaphysis fractures using Ender nails. Methods Eighteen patients who underwent osteosynthesis of humeral diaphysis fractures using Ender nails were evaluated. In addition to the clinical and radiographic evaluations, patients with a minimum of one year of follow-up were assessed by means of the Constant, American Shoulder and Elbow Surgeons (ASES), Mayo Clinic and Simple Shoulder Value (SSV) functional scores, and in relation to the degree of satisfaction with the final result. The fixation technique used was by means of an anterograde percutaneous route. Results All the patients achieved fracture consolidation, after a mean of 2.9 months (ranging from 2 to 4 months). The mean Constant score was 85.7 (ranging from 54 to 100) and the mean ASES score was 95.9 (ranging from 76 to 100). All the patients achieved the maximum score on the Mayo Clinic scale. Conclusion Fixation of humeral diaphysis fractures using Ender nails by means of a percutaneous technique was shown to be a method with promising preliminary results. PMID:26417566

  11. Carbon dioxide slab laser

    SciTech Connect

    Tulip, J.

    1988-01-12

    A gas slab laser is described comprising: first and second elongated electrodes each including a planar light reflecting surface disposed so as to form a light guide only in a plane perpendicular to the planar surface and to define a gas discharge gap therebetween; a laser gas disposed in the gap; and means for applying a radio frequency current between the first and second electrodes to establish a laser-exciting discharge in the laser gas.

  12. Effects of Crustal Densification in Warm Slabs on In-slab Earthquakes and Episodic Tremors and Slips

    NASA Astrophysics Data System (ADS)

    Wang, K.

    2003-12-01

    During subduction, dehydration may facilitate earthquake rupture in both the slab crust and slab mantle. The up to 15% rock densification that accompanies the metabasalt-eclogite transformation is expected to have several mechanical consequences. In warm slabs such as Cascadia and Nankai, this transformation and mantle serpentine breakdown begin at rather shallow depths (30 - 50 km). The pervasively hydrated upper crust transforms to eclogite under equilibrium conditions, but the transformation of the anhydrous parts of the lower crust is kinetically delayed to greater depths. Therefore, densification begins in a thin layer along the top of the slab. Volume reduction gives rise to an equivalent stretching force in the thin layer in all slab-parallel directions, activating existing faults and developing new fractures. Analogous to a weak layer sandwiched between, and bonded to, two strong layers under stretching, fracture spacing in the weak layer scales with the layer thickness. The theory predicts that the densified thin layer must be ~{!0~}shattered~{!1~}. The shattered upper crust may have numerous small earthquakes but does not favor large ruptures. In contrast, the much more uniform lower crust and mantle can host larger ruptures, although seismic ruptures occur only in the limited hydrated parts. This explains the observation that relatively few earthquakes deeper inside the slab tend to have larger magnitudes than those just below the slab surface. For example, three recent damaging events (1999 Oaxaca, Mexico; 2001 Geiyo, Nankai; 2001 Nisqually, Cascadia) in warm slabs all occurred in the lower crust or mantle. The densification is generally a steady state process: An increasingly thinner slab moves into an increasingly thinner subduction "slot" continuously, with the downdip width of transition from normal to thinned crust scaling linearly with the subduction rate. However, at the fracture scale, the process is highly nonlinear, and there must be small

  13. Biomechanical comparison of two intraoperative mobilization techniques for maxillary distraction osteogenesis: Down-fracture versus non-down-fracture

    PubMed Central

    Yang, Lili; Suzuki, Eduardo Yugo; Suzuki, Boonsiva

    2014-01-01

    Purposes: The purpose of this study was to compare the distraction forces and the biomechanical effects between two different intraoperative surgical procedures (down-fracture [DF] and non-DF [NDF]) for maxillary distraction osteogenesis. Materials and Methods: Eight patients were assigned into two groups according to the surgical procedure: DF, n = 6 versus NDF, n = 2. Lateral cephalograms taken preoperatively (T1), immediately after removal of the distraction device (T2), and after at least a 6 months follow-up period (T3) were analyzed. Assessment of distraction forces was performed during the distraction period. The Mann–Whitney U-test was used to compare the difference in the amount of advancement, the maximum distraction force and the amount of relapse. Results: Although a significantly greater amount of maxillary movement was observed in the DF group (median 9.5 mm; minimum-maximum 7.9-14.1 mm) than in the NDF group (median 5.9 mm; minimum-maximum 4.4-7.6 mm), significantly lower maximum distraction forces were observed in the DF (median 16.4 N; minimum-maximum 15.1-24.6 N) than in the NDF (median 32.9 N; minimum-maximum 27.6-38.2 N) group. A significantly greater amount of dental anchorage loss was observed in the NDF group. Moreover, the amount of relapse observed in the NDF group was approximately 3.5 times greater than in the DF group. Conclusions: In this study, it seemed that, the use of the NDF procedure resulted in lower levels of maxillary mobility at the time of the maxillary distraction, consequently requiring greater amounts of force to advance the maxillary bone. Moreover, it also resulted in a reduced amount of maxillary movement, a greater amount of dental anchorage loss and poor treatment stability. PMID:25593865

  14. A comparative study of trochanteric and basicervical fractures of the femur treated with the Ender and McLaughlin techniques.

    PubMed

    Indemini, E; Clerico, P; Fenoglio, E; Mariotti, U

    1982-09-01

    Endomedullary nailing as proposed by Ender is an important alternative in the treatment of trochanteric and basicervical fractures of the femur (Amici et al., 1980; Carret et al., 1980; Ender, 1970; Kempf et al., 1979; Zinghi et al., 1979). Rush's concept (Eiffel Tower, for the distal epiphysis) is reproposed with some variations and transposed to the femoral neck. The aim of the operation differs from that of the nail and plate technique in that, instead of trying to achieve anatomical reconstruction, an immediate functional by-pass of the fractured part is attempted. After using this technique for three years, we compared the old method, which we had not abandoned, the McLaughlin nail and plate, with the new Ender nail.

  15. The hip prosthesis in lateral femur fracture: current concepts and surgical technique

    PubMed Central

    Giannotti, Stefano; Bottai, Vanna; Dell’Osso, Giacomo; De Paola, Gaia; Bugelli, Giulia; Guido, Giulio

    2014-01-01

    Summary The third proximal femur fractures are divided into medial and lateral ones. For medial fractures already exists unanimity of thought for the choice of treatment that involves the prosthetic replacement of the hip joint in patients over 60 without indications to the synthesis. Regarding the lateral femur fractures this unanimity does not exist yet even if the majority of surgeons practice treatment with osteosynthesis. We want to highlight if there are any types of lateral fractures associated with patient’s clinical condition in which it might be more useful to a prosthetic replacement with the aim of being able to allow a total load and earlier deambulation, reducing complications related to a possible patient immobilization. PMID:25568653

  16. The hip prosthesis in lateral femur fracture: current concepts and surgical technique.

    PubMed

    Giannotti, Stefano; Bottai, Vanna; Dell'Osso, Giacomo; De Paola, Gaia; Bugelli, Giulia; Guido, Giulio

    2014-09-01

    The third proximal femur fractures are divided into medial and lateral ones. For medial fractures already exists unanimity of thought for the choice of treatment that involves the prosthetic replacement of the hip joint in patients over 60 without indications to the synthesis. Regarding the lateral femur fractures this unanimity does not exist yet even if the majority of surgeons practice treatment with osteosynthesis. We want to highlight if there are any types of lateral fractures associated with patient's clinical condition in which it might be more useful to a prosthetic replacement with the aim of being able to allow a total load and earlier deambulation, reducing complications related to a possible patient immobilization. PMID:25568653

  17. Fractal characterization of fracture networks: An improved box-counting technique

    NASA Astrophysics Data System (ADS)

    Roy, Ankur; Perfect, Edmund; Dunne, William M.; McKay, Larry D.

    2007-12-01

    Box counting is widely used for characterizing fracture networks as fractals and estimating their fractal dimensions (D). If this analysis yields a power law distribution given by N ∝ r-D, where N is the number of boxes containing one or more fractures and r is the box size, then the network is considered to be fractal. However, researchers are divided in their opinion about which is the best box-counting algorithm to use, or whether fracture networks are indeed fractals. A synthetic fractal fracture network with a known D value was used to develop a new algorithm for the box-counting method that returns improved estimates of D. The method is based on identifying the lower limit of fractal behavior (rcutoff) using the condition ds/dr → 0, where s is the standard deviation from a linear regression equation fitted to log(N) versus log(r) with data for r < rcutoff sequentially excluded. A set of 7 nested fracture maps from the Hornelen Basin, Norway was used to test the improved method and demonstrate its accuracy for natural patterns. We also reanalyzed a suite of 17 fracture trace maps that had previously been evaluated for their fractal nature. The improved estimates of D for these maps ranged from 1.56 ± 0.02 to 1.79 ± 0.02, and were much greater than the original estimates. These higher D values imply a greater degree of fracture connectivity and thus increased propensity for fracture flow and the transport of miscible or immiscible chemicals.

  18. Reasonable Temperature Schedules for Cold or Hot Charging of Continuously Cast Steel Slabs

    NASA Astrophysics Data System (ADS)

    Li, Yang; Chen, Xin; Liu, Ke; Wang, Jing; Wen, Jin; Zhang, Jiaquan

    2013-12-01

    Some continuously cast steel slabs are sensitive to transverse fracture problems during transportation or handling away from their storage state, while some steel slabs are sensitive to surface transverse cracks during the following rolling process in a certain hot charging temperature range. It is revealed that the investigated steel slabs with high fracture tendency under room cooling condition always contain pearlite transformation delayed elements, which lead to the internal brittle bainitic structure formation, while some microalloyed steels exhibit high surface crack susceptibility to hot charging temperatures due to carbonitride precipitation. According to the calculated internal cooling rates and CCT diagrams, the slabs with high fracture tendency during cold charging should be slowly cooled after cutting to length from hot strand or charged to the reheating furnace directly above their bainite formation temperatures. Based on a thermodynamic calculation for carbonitride precipitation in austenite, the sensitive hot charging temperature range of related steels was revealed for the determination of reasonable temperature schedules.

  19. EVALUATION OF PATIENTS UNDERGOING FIXATION OF DIAPHYSEAL HUMERAL FRACTURES USING THE MINIMALLY INVASIVE BRIDGE-PLATE TECHNIQUE

    PubMed Central

    Superti, Mauro José; Martynetz, Fábio; Falavinha, Ricardo Sprenger; Fávaro, Rodrigo Caldonazzo; Boas, Luis Felipe Villas; Filho, Salim Mussi; Martynetz, Juliano; Ribas, Bruno

    2015-01-01

    Objective: The aim was to describe the experience of our group in treating humeral shaft fractures using the bridge–plate technique via an anterior approach. Methods: Seventeen patients with acute diaphyseal humeral fractures with an indication for surgical treatment who were operated in 2006–2010 were evaluated. The AO and Gustilo & Anderson classifications were used. All the patients were operated using the anterior bridge-plate technique and completed a follow–up period of at least twelve months. Results: Sixteen men and one woman were treated. Their mean age was 31.8 years (18–52). Among the injury mechanisms found were: five motorcycle accidents, four car accidents, three fractures due to firearm projectiles, two falls to the ground and finally, with one case each, assault, crushing and being run over. Eight patients had open fractures: two grade I, one grade II, four grade IIIa and one grade IIIb, according to the Gustilo-Anderson classification. In relation to the AO classification, we found: one 12A1, three 12A2, four 12A3, one 12B1, four 12 B2, three 12B3 and one 12C2. The mean postoperative follow-up was 25 months (12–48). As complications, two patients had pain in the elbow and a ROM deficit and one had deep infection. The mean time taken to achieve consolidation was 17.5 weeks. There was no loss of reduction, pseudarthrosis or malunion in this series of patients. Conclusion: The authors believe that the technique described has low rates of complications and morbidity, with good initial results, although the series is limited by the small sample. PMID:27042639

  20. Successful stabilisation of a type III paediatric tibial eminence fracture using a tensioned wire technique.

    PubMed

    Archer, Matthew; Parkin, Tom; Latimer, Mark David

    2016-01-01

    We report the case of an 11-year-old boy presenting with a type III tibial eminence fracture. The fracture fragment was reduced arthroscopically. Two 1.6 mm retrograde K-wires were inserted from the tibial metaphysis across the physis and into the fracture fragment using a standard anterior cruciate ligament tibial tunnel guide. Once the wires were clearly visible within the joint the tips were bent over by ∼120°. The wires were then tensioned around a single small fragment screw inserted into the tibial metaphysis. An exceptionally strong fixation was achieved. The boy was mobilised without a brace. The wires were removed at 12 weeks and he returned to full activity at 14 weeks. PMID:27646317

  1. Particle Imaging Velocimetry Technique Development for Laboratory Measurement of Fracture Flow Inside a Pressure Vessel Using Neutron Imaging

    SciTech Connect

    Polsky, Yarom; Bingham, Philip R; Bilheux, Hassina Z; Carmichael, Justin R

    2015-01-01

    This paper will describe recent progress made in developing neutron imaging based particle imaging velocimetry techniques for visualizing and quantifying flow structure through a high pressure flow cell with high temperature capability (up to 350 degrees C). This experimental capability has great potential for improving the understanding of flow through fractured systems in applications such as enhanced geothermal systems (EGS). For example, flow structure measurement can be used to develop and validate single phase flow models used for simulation, experimentally identify critical transition regions and their dependence on fracture features such as surface roughness, and study multiphase fluid behavior within fractured systems. The developed method involves the controlled injection of a high contrast fluid into a water flow stream to produce droplets that can be tracked using neutron radiography. A description of the experimental setup will be provided along with an overview of the algorithms used to automatically track droplets and relate them to the velocity gradient in the flow stream. Experimental results will be reported along with volume of fluids based simulation techniques used to model observed flow.

  2. Development of Reservoir Characterization Techniques and Production Models for Exploiting Naturally Fractured Reservoirs

    SciTech Connect

    Wiggins, Michael L.; Brown, Raymon L.; Civan, Faruk; Hughes, Richard G.

    2003-02-11

    This research was directed toward developing a systematic reservoir characterization methodology which can be used by the petroleum industry to implement infill drilling programs and/or enhanced oil recovery projects in naturally fractured reservoir systems in an environmentally safe and cost effective manner. It was anticipated that the results of this research program will provide geoscientists and engineers with a systematic procedure for properly characterizing a fractured reservoir system and a reservoir/horizontal wellbore simulator model which can be used to select well locations and an effective EOR process to optimize the recovery of the oil and gas reserves from such complex reservoir systems.

  3. Influence of immediate dentin sealing techniques on cuspal deflection and fracture resistance of teeth restored with composite resin inlays.

    PubMed

    Oliveira, L; Mota, E G; Borges, G A; Burnett, L H; Spohr, A M

    2014-01-01

    SUMMARY This research evaluated the influence of immediate dentin sealing (IDS) techniques on cuspal deflection and fracture resistance of teeth restored with composite resin inlays. Forty-eight maxillary premolars were divided into four groups: G1, sound teeth (control); G2, without IDS; G3, IDS with Clearfil SE Bond (CSE); and G4, IDS with CSE and Protect Liner F. The teeth from groups 2, 3, and 4 received mesio-distal-occlusal preparations. The impressions were made with vinyl polysiloxane, followed by provisional restoration and storage in water for seven days. The impressions were poured using type IV die stone, and inlays with Filtek Z250 composite resin were built over each cast. The inlays were luted with Panavia F. After storage in water for 72 hours, a 200-N load was applied on the occlusal surface using a metal sphere connected to a universal testing machine, and the cuspal deflection was measured with a micrometer. The specimens were then submitted to an axial load until failure. The following mean cuspal deflection (μm) and mean fracture resistance (N) followed by the same lowercase letter represent no statistical difference by analysis of variance and Tukey (p<0.05): cuspal deflection: G1, 3.1 ± 1.5(a); G2, 10.3 ± 4.6(b); G3, 5.5 ± 1.8(ac); and G4, 7.7 ± 5.1(bc); fracture resistance: G1, 1974 ± 708(a); G2, 1162 ± 474(b); G3, 700 ± 280(b); and G4, 810 ± 343(b). IDS with CSE allowed cuspal deflection comparable with that associated with sound teeth. The application of Protect Liner F did not contribute to a decrease in cuspal deflection. The IDS techniques did not influence the fracture resistance of teeth.

  4. An enhanced HOWFARLESS option for DOSXYZnrc simulations of slab geometries

    SciTech Connect

    Babcock, Kerry; Cranmer-Sargison, Gavin; Sidhu, Narinder

    2008-09-15

    The Monte Carlo code DOSXYZnrc is a valuable instrument for calculating absorbed dose within a three-dimensional Cartesian geometry. DOSXYZnrc includes several variance reduction techniques used to increase the efficiency of the Monte Carlo calculation. One such technique is HOWFARLESS which is used to increase the efficiency of beam commissioning calculations in homogeneous phantoms. The authors present an enhanced version of HOWFARLESS which extends the application to include phantoms inhomogeneous in one dimension. When the enhanced HOWFARLESS was used, efficiency increases as high as 14 times were observed without any loss in dose accuracy. The efficiency gains of an enhanced HOWFARLESS simulation was found to be dependent on both slab geometry and slab density. As the number of two-dimensional voxel layers per slab increases, so does the efficiency gain. Also, as the mass density of a slab is decreased, the efficiency gains increase.

  5. SUB-SLAB PROBE INSTALLATION

    EPA Science Inventory

    Sub-slab sampling has become an integral part of vapor intrusion investigations. It is now recommended in guidance documents developed by EPA and most states. A method for sub-slab probe installation was devised in 2002, presented at conferences through 2005, and finally docume...

  6. [Thermoluminescence Slab Dosimeter].

    PubMed

    Shinsho, Kiyomitsu; Koba, Yusuke; Tamatsu, Satoshi; Sakurai, Noboru; Wakabayashi, Genichiro; Fukuda, Kazusige

    2013-01-01

    In 1953 F. Daniels et al. used the property of thermoluminescence in dosimetry for the first time. Since then, numerous TLD have been developed. 2D TLD was investigated for the first time in 1972 by P Broadhead. However, due to excessive fading, difficulties with handling and the time required for measurements, development stalled. At the current time, the majority of TLD are used in small scale, localized dosimetry with a wide dynamic range and personal dosimeters for exposure management. Urushiyama et. al. have taken advantage of the commoditization of CCD cameras in recent years--making large area, high resolution imaging easier--to introduce and develop a 2D TLD. It is expected that these developments will give rise to a new generation of applications for 2D TL dosimetry. This paper introduces the "TL Slab Dosimeter" developed jointly by Urushiyama et. al. and our team, its measurement system and several typical usage scenarios.

  7. Complicated Crown-Root Fracture Treated Using Reattachment Procedure: A Single Visit Technique

    PubMed Central

    Rajput, Akhil; Talwar, Sangeeta; Ataide, Ida; Verma, Mahesh; Wadhawan, Neeraj

    2011-01-01

    Complicated crown-root fracture of maxillary central and lateral incisors is common in case of severe trauma or sports-related injury. It happens because of their anterior positioning in oral cavity and protrusive eruptive pattern. On their first dental visit, these patients are in pain and need emergency care. Because of impaired function, esthetics, and phonetics, such patients are quite apprehensive during their emergency visit. Successful pain management with immediate restoration of function, esthetics and phonetics should be the prime objective while handling such cases. This paper describes immediate treatment of oblique crown root fracture of maxillary right lateral incisor with reattachment procedure using light transmitting fiber post. After two and half years, the reattached fragment still has satisfying esthetics and excellent function. PMID:22690345

  8. Calculation and comparison of thermal effect in laser diode pumped slab lasers with different pumping structures

    NASA Astrophysics Data System (ADS)

    Huang, Feng; Jiang, Nan; Wang, Yuefeng; Dong, Wei; Niu, Yanxiong

    2008-03-01

    Laser diode (LD) pumped slab laser, as an important high average power solid-state laser, is a promising laser source in military and industrial fields. The different laser diode pumping structures lead to different thermal effect in the slab gain medium. The thermal and stress analysis of slab laser with different pumping structure are performed by finite element analysis (FEA) with the software program ANSYS. The calculation results show that the face pumped and cooled laser results in a near one-dimension temperature distribution and eliminates thermal stress induced depolarization. But the structure is low pump efficiency due to the small thickness of slabs and the requirement to cool and pump through the same faces. End-pumped slab laser is high pump efficiency and excellent mode match, but its pumping arrangement is fairly complicated. The edge-pumped face-cooling slab laser's pump efficiency is better than face-pumping, and its pumping structure is simpler than end-pumped laser, but the tensile stress on surfaces may initiate failure of the gain medium so it is important to design so that the stress is well below the stress fracture limit. The comparison of the thermal effects with different pumping structure shows that, the edge-pumped slab laser has engineering advantages in high power slab laser's application. Furthermore, the end-pumped slab laser tends to get the best beam quality, so it is fit for the application which has a special requirement on laser beam quality.

  9. Fracture toughness of solid oxide fuel cell anode substrates determined by a double-torsion technique

    NASA Astrophysics Data System (ADS)

    Pećanac, G.; Wei, J.; Malzbender, J.

    2016-09-01

    Planar solid oxide fuel cell anode substrates are exposed to high mechanical loads during assembly, start-up, steady-state operation and thermal cycling. Hence, characterization of mechanical stability of anode substrates under different oxidation states and at relevant temperatures is essential to warrant a reliable operation of solid oxide fuel cells. As a basis for mechanical assessment of brittle supports, two most common anode substrate material variants, NiO-3YSZ and NiO-8YSZ, were analyzed in this study with respect to their fracture toughness at room temperature and at a typical stack operation temperature of 800 °C. The study considered both, oxidized and reduced materials' states, where also an outlook is given on the behavior of the re-oxidized state that might be induced by malfunctions of sealants or other functional components. Aiming at the improvement of material's production, different types of warm pressed and tape cast NiO-8YSZ substrates were characterized in oxidized and reduced states. Overall, the results confirmed superior fracture toughness of 3YSZ compared to 8YSZ based composites in the oxidized state, whereas in the reduced state 3YSZ based composites showed similar fracture toughness at room temperature, but a higher value at 800 °C compared to 8YSZ based composites. Complementary microstructural analysis aided the interpretation of mechanical characterization.

  10. A Novel Two-Step Technique for Retrieving Fractured Peripherally Inserted Central Catheter Segments Migrating into the Heart or the Pulmonary Artery

    PubMed Central

    Peng, Juan; Zhang, Xiao-Ming; Xu, Hao; Miao, Nan-Dong; Ren, Yong-Jun; Liu, Kang; Min, Xu-Li; Yang, Ke; Yang, Shi; Yang, Cheng

    2016-01-01

    Objective. To report the experience of a percutaneous technique for retrieving fractured peripherally inserted central catheter (PICC) segments migrating into the heart or the pulmonary artery. Method. From April 2013 to July 2015, we performed percutaneous retrieval of fractured PICC segments migrating into the heart or the pulmonary artery in five cancer patients who had undergone chemotherapy via PICC. The fractures were diagnosed with chest plain radiography. The patients included three cases of breast cancer, one case of rectal cancer, and one case of lower limb Ewing's tumor. The fractures were retained in the vessels of the patients for 1 to 3 days. All the fractures were retrieved by using a novel two-step technique in the digital subtraction angiography (DSA) suite. This two-step technique involves inserting a pigtail catheter to the heart or the pulmonary artery to grasp the fractured catheter fragment and bring it to the lower segment of the inferior vena cava, followed by grasping and removing the catheter fragment with a retrieval loop system of the vena cava filter retrieval set. Result. The fractured PICC segments were removed successfully in all five patients via unilateral (four patients) or bilateral (one patient) femoral vein access. No complications occurred during the interventional procedure. Conclusion. Percutaneous retrieval can be a safe, convenient, and minimally invasive method for the removal of fractured PICC segments. The technique reported in this paper will be applicable for the retrieval of fractured PICC segments and other catheter fragments migrating into the heart or the pulmonary artery. PMID:27642604

  11. A Novel Two-Step Technique for Retrieving Fractured Peripherally Inserted Central Catheter Segments Migrating into the Heart or the Pulmonary Artery.

    PubMed

    Peng, Juan; Zhang, Xiao-Ming; Yang, Lin; Xu, Hao; Miao, Nan-Dong; Ren, Yong-Jun; Liu, Kang; Min, Xu-Li; Yang, Ke; Yang, Shi; Yang, Cheng

    2016-01-01

    Objective. To report the experience of a percutaneous technique for retrieving fractured peripherally inserted central catheter (PICC) segments migrating into the heart or the pulmonary artery. Method. From April 2013 to July 2015, we performed percutaneous retrieval of fractured PICC segments migrating into the heart or the pulmonary artery in five cancer patients who had undergone chemotherapy via PICC. The fractures were diagnosed with chest plain radiography. The patients included three cases of breast cancer, one case of rectal cancer, and one case of lower limb Ewing's tumor. The fractures were retained in the vessels of the patients for 1 to 3 days. All the fractures were retrieved by using a novel two-step technique in the digital subtraction angiography (DSA) suite. This two-step technique involves inserting a pigtail catheter to the heart or the pulmonary artery to grasp the fractured catheter fragment and bring it to the lower segment of the inferior vena cava, followed by grasping and removing the catheter fragment with a retrieval loop system of the vena cava filter retrieval set. Result. The fractured PICC segments were removed successfully in all five patients via unilateral (four patients) or bilateral (one patient) femoral vein access. No complications occurred during the interventional procedure. Conclusion. Percutaneous retrieval can be a safe, convenient, and minimally invasive method for the removal of fractured PICC segments. The technique reported in this paper will be applicable for the retrieval of fractured PICC segments and other catheter fragments migrating into the heart or the pulmonary artery. PMID:27642604

  12. Radiation characteristics of tapered slab waveguides

    NASA Astrophysics Data System (ADS)

    Scheggi, A. M.; Falciai, R.; Brenci, M.

    1983-01-01

    The application of ray optics to the evaluation of near- and far-field radiation patterns of a slab waveguide taper is discussed, noting the importance of calculating the power that can be extracted from the core at the end of the waveguide related to the near-field configurations. A multimode, tapered slab waveguide with a homogeneous core and unlimited cladding is considered. It is pointed out that as the ray proceeds on its zigzag path down the taper, its propagation angle increases from reflection to reflection and eventually surpasses the limit angle of total reflection. To obtain an overall idea of the range of ray angles accepted at the smaller end of the taper, the Williamson (1952) method is used; this makes it possible, through a simple geometrical construction, to trace the ray in a linear cone. It is found that the ray-tracing technique can constitute an adequate tool in the analysis and design of tapered multimode waveguides.

  13. Implant Prosthetic Rehabilitation with Bone Regenerative Techniques after Fracture of the Upper Central Incisors

    PubMed Central

    Amato, Massimo; Bruno, Vincenzo; Pantaleo, Giuseppe; Cerutti, Antonio; Spagnuolo, Gianrico; Sammartino, Gilberto

    2013-01-01

    A case of implant-bone prosthetic rehabilitation, after the fracture of the maxillary central incisors, which had been treated with grafting of a bone substitute, is reported. This case was followed by the normal procedures of implantology within the traditional timeframe for bone regeneration. However, a barrier membrane was not used which shows that even along with the use of graft material a sufficient amount of bone could be achieved for a subsequent rehabilitation. Therefore, after a five-year follow-up period, osseointegration was maintained with no marginal bone loss. PMID:23762642

  14. Screw-Wire Osteo-Traction: An Adjunctive or Alternative Method of Anatomical Reduction of Multisegment Midfacial Fractures? A Description of Technique and Prospective Study of 40 Patients

    PubMed Central

    O'Regan, Barry; Devine, Maria; Bhopal, Sats

    2013-01-01

    Stable anatomical fracture reduction and segment control before miniplate fixation can be difficult to achieve in comminuted midfacial fractures. Fracture mobilization and reduction methods include Gillies elevation, malar hook, and Dingman elevators. No single method is used universally. Disadvantages include imprecise segment alignment and poor segment stability/control. We have employed screw-wire osteo-traction (SWOT) to address this problem. A literature review revealed two published reports. The aims were to evaluate the SWOT technique effectiveness as a fracture reduction method and to examine rates of revision fixation and plate removal. We recruited 40 consecutive patients requiring open reduction and internal fixation of multisegment midfacial fractures (2009–2012) and employed miniplate osteosynthesis in all patients. SWOT was used as a default reduction method in all patients. The rates of successful fracture reduction achieved by SWOT alone or in combination and of revision fixation and plate removal, were used as outcome indices of the reduction method effectiveness. The SWOT technique achieved satisfactory anatomical reduction in 27/40 patients when used alone. Other reduction methods were also used in 13/40 patients. No patient required revision fixation and three patients required late plate removal. SWOT can be used across the midface fracture pattern in conjunction with other methods or as a sole reduction method before miniplate fixation. PMID:24436763

  15. Screw-wire osteo-traction: an adjunctive or alternative method of anatomical reduction of multisegment midfacial fractures? A description of technique and prospective study of 40 patients.

    PubMed

    O'Regan, Barry; Devine, Maria; Bhopal, Sats

    2013-12-01

    Stable anatomical fracture reduction and segment control before miniplate fixation can be difficult to achieve in comminuted midfacial fractures. Fracture mobilization and reduction methods include Gillies elevation, malar hook, and Dingman elevators. No single method is used universally. Disadvantages include imprecise segment alignment and poor segment stability/control. We have employed screw-wire osteo-traction (SWOT) to address this problem. A literature review revealed two published reports. The aims were to evaluate the SWOT technique effectiveness as a fracture reduction method and to examine rates of revision fixation and plate removal. We recruited 40 consecutive patients requiring open reduction and internal fixation of multisegment midfacial fractures (2009-2012) and employed miniplate osteosynthesis in all patients. SWOT was used as a default reduction method in all patients. The rates of successful fracture reduction achieved by SWOT alone or in combination and of revision fixation and plate removal, were used as outcome indices of the reduction method effectiveness. The SWOT technique achieved satisfactory anatomical reduction in 27/40 patients when used alone. Other reduction methods were also used in 13/40 patients. No patient required revision fixation and three patients required late plate removal. SWOT can be used across the midface fracture pattern in conjunction with other methods or as a sole reduction method before miniplate fixation.

  16. A Simple Technique for the Positioning of a Patient with an above Knee Amputation for an Ipsilateral Extracapsular Hip Fracture Fixation

    PubMed Central

    Davarinos, N.; Ellanti, P.; McCoy, G.

    2013-01-01

    The positioning of the patient on the fracture table is critical to the successful reduction and operative fixation of hip fractures which are fixed using the dynamic hip screw system (DHS). There is a standard setup which is commonly used with relative ease. Yet the positioning of patients with amputations either above or below knee of the affected side can pose a significant challenge. We describe a novel positioning technique used on a 51-year old patient with a right above knee amputation who sustained an intertrochanteric extracapsular hip fracture. PMID:24416607

  17. New Packaging for Amplifier Slabs

    SciTech Connect

    Riley, M.; Thorsness, C.; Suratwala, T.; Steele, R.; Rogowski, G.

    2015-03-18

    The following memo provides a discussion and detailed procedure for a new finished amplifier slab shipping and storage container. The new package is designed to maintain an environment of <5% RH to minimize weathering.

  18. Active part of Charlie--Gibbs fracture zone: A study using sonar and other geophysical techniques

    SciTech Connect

    Searle, R.

    1981-01-10

    A short survey with Gloria side-scan sonar and other geophysical instruments has revealed new information about Charlie--Gibbs fracture zone between 29/sup 0/ and 36 /sup 0/W. The traces of two transform faults have been clearly delineated. They fit small circles about the pole of rotation with an rms error of only about 1 km, but they do not always follow the deepest parts of the transform valleys. The transforms are joined by a short spreading center at 31 /sup 0/45 'W. The median transverse ridge appears to have been produced by normal seafloor spreading at this center and bears identifiable Vine-Matthews magnetic anomalies. A transverse ridge along the eastern inactive part of the northern transform may be an intrusive feature. Considerable thickness of sediment appear to have been deposited in the northern transform valley from Norwegian Sea overflow water passing through the fracture zone, but transverse ridges have prevented the sediment reaching the southern valley.

  19. Approximate techniques for predicting size effects on cleavage fracture toughness (J{sub c})

    SciTech Connect

    Kirk, M.T.; Dodds, R.H. Jr.

    1993-07-01

    This investigation examines the ability of an elastic T-stress analysis coupled with modified boundary layer (MBL) solution to predict stresses ahead of a crack tip in a variety of planar geometries. The approximate stresses are used as input to estimate the effective driving force for cleavage fracture (J{sub 0}) using the micromechanically based approach introduced by Dodds and Anderson. Finite element analyses for a wide variety of planar cracked geometries are conducted which have elastic biaxiality parameters ({beta}) ranging from {minus}0.99 (very low constraint) to +2.96 (very high constraint). The magnitude and sign of {beta} indicate the rate at which crack-tip constraint changes with increasing applied load. All results pertain to a moderately strain hardening material (strain hardening exponent ({eta}) of 10). These analyses suggest that {beta} is an effective indicator of both the accuracy of T-MBL estimates of J{sub 0} and of applicability limits on evolving fracture analysis methodologies (i.e. T-MBL, J-Q, and J/J{sub 0}). Specifically, when 1{beta}1>0.4 these analyses show that the T-MBL approximation of J{sub 0} is accurate to within 20% of a detailed finite-element analysis. As ``structural type`` configurations, i.e. shallow cracks in tension, generally have 1{beta}1>0.4, it appears that only an elastic analysis may be needed to determine reasonably accurate J{sub 0} values for structural conditions.

  20. Optimization of reinforced concrete slabs

    NASA Technical Reports Server (NTRS)

    Ferritto, J. M.

    1979-01-01

    Reinforced concrete cells composed of concrete slabs and used to limit the effects of accidental explosions during hazardous explosives operations are analyzed. An automated design procedure which considers the dynamic nonlinear behavior of the reinforced concrete of arbitrary geometrical and structural configuration subjected to dynamic pressure loading is discussed. The optimum design of the slab is examined using an interior penalty function. The optimization procedure is presented and the results are discussed and compared with finite element analysis.

  1. Topical report on subsurface fracture mapping from geothermal wellbores. Phase I. Pulsed radar techniques. Phase II. Conventional logging methods. Phase III. Magnetic borehole ranging

    SciTech Connect

    Hartenbaum, B.A.; Rawson, G.

    1980-09-01

    To advance the state-of-the-art in Hot Dry Rock technology, an evaluation is made of (i) the use of radar to map far-field fractures, (ii) the use of more than twenty different conventional well logging tools to map borehole-fracture intercepts, and (iii) the use of magnetic dipole ranging to determine the relative positions of the injection well and the production well within the fractured zone. It is found that according to calculations, VHF backscatter radar has the potential for mapping fractures within a distance of 50 +- 20 meters from the wellbore. A new technique for improving fracture identification is presented. Analyses of extant data indicate that when used synergistically the (1) caliper, (2) resistivity dipmeter, (3) televiewer, (4) television, (5) impression packer, and (6) acoustic transmission are useful for mapping borehole-fracture intercepts. Improvements in both data interpretation techniques and high temperature operation are required. The surveying of one borehole from another appears feasible at ranges of up to 200 to 500 meters by using a low frequency magnetic field generated by a moderately strong dipole source (a solenoid) located in one borehole, a sensitive B field detector that traverses part of the second borehole, narrow band filtering, and special data inversion techniques.

  2. Functional results of vertebral augmentation techniques in pathological vertebral fractures of myelomatous patients.

    PubMed Central

    Köse, Kamil Cagri; Cebesoy, Oguz; Akan, Burak; Altinel, Levent; Dinçer, Derya; Yazar, Tarik

    2006-01-01

    INTRODUCTION: This is a retrospective study to determine the effects of vertebroplasty and kyphoplasty on quality of life in multiple myeloma patients with spinal compression fractures. MATERIAL AND METHODS: Thirty-four patients with primary multiple myeloma were treated for symptomatic compression fractures between June 2003 and June 2005. Kyphoplasty was applied to 22 levels in 18 and vertebroplasty to 28 levels in 16 patients. The pain-related disability was evaluated for every single daily living activity using visual analog scale (VAS) over 10 points. (pain at rest, walking, sitting-standing, taking a shower and wearing clothes). (This evaluation is performed to every patient with degenerative disorders of the spine upon admission to our clinic.) Overall VAS scores were evaluated over 50 points (0 minimum, 50 maximum) preoperatively, at postoperative six weeks, six months and at one year prior to taking analgesics. The amount of analgesic use was recorded. Data was analyzed statistically using variance analysis, Friedman's multiple comparison test and Student's t test. RESULTS: The mean overall pain score in the kyphoplasty group decreased from a preoperative value of 36 to 12.13 at the sixth postoperative week, to 8.63 at the sixth month and to 9.72 at one year. (p<0.001). The mean overall pain score in the vertebroplasty group decreased from a preoperative value of 37.83 to 15.33 at the sixth postoperative week, to 12.17 at sixth months and to 13.47 at one year. (p<0.001). Student's t test was used to analyze the percentage of differences in overall pain score. Difference between groups was not statistically significant at the sixth week (p=0.106) but was statistically significant both at the sixth month (p=0.024) and at one year (p=0.027) in favor of kyphoplasty group. No secondary collapse was observed in adjacent levels in both groups. There were no intrapostoperative neurologic/pulmonary complications in both groups. Analgesics usage significantly

  3. Surface waves on a grounded dielectric slab covered by a resistive sheet

    NASA Technical Reports Server (NTRS)

    Shively, David

    1993-01-01

    This paper examines surface wave propagation in a grounded dielectric slab covered with a resistive sheet. Transcendental equations are derived for each polarization and are solved using iterative techniques. Attention and phase velocity are shown for a representative geometry. The results are applicable to both a grounded slab covered with a resistive sheet and an ungrounded slab covered on each side with a resistive sheet.

  4. Trans-Endplate Pedicle Pillar System in Unstable Spinal Burst Fractures: Design, Technique, and Mechanical Evaluation

    PubMed Central

    Zhao, Chunfeng; Hongo, Michio; Ilharreborde, Brice; Zhao, Kristin D.; Currier, Bradford L.; An, Kai-Nan

    2015-01-01

    Background Short-segment pedicle screw instrumentation (SSPI) is used for unstable burst fractures to correct deformity and stabilize the spine for fusion. However, pedicle screw loosening, pullout, or breakage often occurs due to the large moment applied during spine motion, leading to poor outcomes. The purpose of this study was to test the ability of a newly designed device, the Trans-Endplate Pedicle Pillar System (TEPPS), to enhance SSPI rigidity and decrease the screw bending moment with a simple posterior approach. Methods Six human cadaveric spines (T11-L3) were harvested. A burst fracture was created at L1, and the SSPI (Moss Miami System) was used for SSPI fixation. Strain gauge sensors were mounted on upper pedicle screws to measure screw load bearing. Segmental motion (T12-L2) was measured under pure moment of 7.5 Nm. The spine was tested sequentially under 4 conditions: intact; first SSPI alone (SSPI-1); SSPI+TEPPS; and second SSPI alone (SSPI-2). Results SSPI+TEPPS increased fixation rigidity by 41% in flexion/extension, 28% in lateral bending, and 37% in axial rotation compared with SSPI-1 (P<0.001), and it performed even better compared to SSPI-2 (P<0.001 for all). Importantly, the bending moment on the pedicle screws for SSPI+TEPPS was significantly decreased 63% during spine flexion and 47% in lateral bending (p<0.001). Conclusion TEPPS provided strong anterior support, enhanced SSPI fixation rigidity, and dramatically decreased the load on the pedicle screws. Its biomechanical benefits could potentially improve fusion rates and decrease SSPI instrumentation failure. PMID:26502352

  5. Dynamics of Mantle Circulation Associated with Slab Window Formation: Insights from 3D Laboratory Models

    NASA Astrophysics Data System (ADS)

    Guillaume, B.; Funiciello, F.; Moroni, M.; Faccenna, C.; Martinod, J.

    2009-12-01

    Slab window can form either by the intersection of a spreading ridge with a subduction zone or because of internal deformation of the slab that leads to its disruption. The main consequences of this phenomenon are the modifications of the physical, chemical and thermal conditions in the backarc mantle that in turn affect the tectonic and magmatic evolution of the overriding plate. We performed laboratory models of a two-layer linear viscous slab (silicone putty)-upper mantle (glucose syrup) system to quantitatively investigate the pattern of mantle circulation within the slab window (using Feature Tracking image analysis technique) and its influence on the kinematics of the system. Two different geometries have been tested considering a window located (a) at slab edges or (b) within the slab. Kinematic consequences of slab window have been explored to understand the dynamics of the mantle-slab interaction. Configuration (a) implies a reduction of the slab width (W) during subduction and is characterized by toroidal fluxes around the slab edges. The abrupt opening of lateral slab windows produces an acceleration of the trench retreat and subduction velocity, such as 40% for a three-fold width reduction. We interpret this behavior as mostly due to the decrease in the toroidal flow inside subduction windows, scaling with W2. Configuration (b) has been designed to explore the pattern of mantle flow within the window in the case of a laterally constrained subduction system. Slab window, which had a width (Ww) fixed to 15 % of the slab width, opened in the trench-perpendicular direction. It produced the formation of two toroidal mantle cells, centered on the slab midpoint and laterally growing as the slab window enlarged. Particles extruded through the slab window did not mix with particles located in the mantle wedge, the boundary between both reaching distances from the trench up to 3×Ww in the trench-perpendicular direction, and up to 1.5×Ww from the window edge in

  6. Subduction of fracture zones

    NASA Astrophysics Data System (ADS)

    Constantin Manea, Vlad; Gerya, Taras; Manea, Marina; Zhu, Guizhi; Leeman, William

    2013-04-01

    Since Wilson proposed in 1965 the existence of a new class of faults on the ocean floor, namely transform faults, the geodynamic effects and importance of fracture zone subduction is still little studied. It is known that oceanic plates are characterized by numerous fracture zones, and some of them have the potential to transport into subduction zones large volumes of water-rich serpentinite, providing a fertile water source for magma generated in subduction-related arc volcanoes. In most previous geodynamic studies, subducting plates are considered to be homogeneous, and there is no clear indication how the subduction of a fracture zone influences the melting pattern in the mantle wedge and the slab-derived fluids distribution in the subarc mantle. Here we show that subduction of serpentinized fracture zones plays a significant role in distribution of melt and fluids in the mantle wedge above the slab. Using high-resolution tree-dimensional coupled petrological-termomechanical simulations of subduction, we show that fluids, including melts and water, vary dramatically in the region where a serpentinized fracture zone enters into subduction. Our models show that substantial hydration and partial melting tend to concentrate where fracture zones are being subducted, creating favorable conditions for partially molten hydrous plumes to develop. These results are consistent with the along-arc variability in magma source compositions and processes in several regions, as the Aleutian Arc, the Cascades, the Southern Mexican Volcanic Arc, and the Andean Southern Volcanic Zone.

  7. Nose fracture

    MedlinePlus

    Fracture of the nose; Broken nose; Nasal fracture; Nasal bone fracture; Nasal septal fracture ... A fractured nose is the most common fracture of the face. It ... with other fractures of the face. Sometimes a blunt injury can ...

  8. V-rod technique for direct repair surgery of pediatric lumbar spondylolysis combined with posterior apophyseal ring fracture.

    PubMed

    Sumita, Takayuki; Sairyo, Koichi; Shibuya, Isao; Kitahama, Yoshihiro; Kanamori, Yasuo; Matsumoto, Hironori; Koga, Soichi; Kitagawa, Yasuhiro; Dezawa, Akira

    2013-06-01

    We report a pediatric baseball player having both a fracture of the posterior ring apophysis and spondylolysis. He was presented to a primary care physician complaining of back pain and leg pain. Despite conservative treatment for 3 months, the pain did not subside. He was referred to our clinic, and surgical intervention was carried out. First, a bony fragment of the caudal L5 apophyseal ring was removed following fenestration at the L5-S interlaminal space, bilaterally: and decompression of the bilateral S1 nerve roots was confirmed. Next, pseudoarthrosis of the L5 pars was refreshed and pedicle screws were inserted bilaterally. A v-shaped rod was inserted beneath the L5 spinous process, which stabilized the pars defects. After the surgery, back pain and leg pain completely disappeared. In conclusion, the v-rod technique is appropriate for the spondylolysis direct repair surgery, especially, in case the loose lamina would have a partial laminotomy.

  9. Use of advanced borehole geophysical techniques to delineate fractured-rock ground-water flow and fractures along water-tunnel facilities in northern Queens County, New York

    USGS Publications Warehouse

    Stumm, Frederick; Chu, Anthony; Lange, Andrew D.; Paillet, Frederick L.; Lane,, John W.

    2001-01-01

    Advanced borehole geophysical methods were used to assess the geohydrology of crystalline bedrock along the course of a new water tunnel for New York City. The logging methods include natural gamma, spontaneous potential, single-point resistance, mechanical and acoustic caliper, focused electromagnetic induction, electromagnetic resistivity, magnetic susceptibility, borehole-fluid temperature and conductance, differential temperature, heat-pulse flowmeter, acoustic televiewer, borehole deviation, optical televiewer, and borehole radar. Integrated interpretation of the geophysical logs from an 825-foot borehole (1) provided information on the extent, orientation, and structure (foliation and fractures) within the entire borehole, including intensely fractured intervals from which core recovery may be poor; (2) delineated transmissive fracture zones intersected by the borehole and provided estimates of their transmissivity and hydraulic head; and (3) enabled mapping of the location and orientation of structures at distances as much as 100 ft from the borehole. Analyses of the borehole-wall image and the geophysical logs from the borehole on Crescent Street, in northern Queens County, are presented here to illustrate the application of the methods. The borehole penetrates gneiss and other crystalline bedrock that has predominantly southeastward dipping foliation and nearly horizontal and southeastward-dipping fractures. The heat-pulse flowmeter logs obtained under pumping and nonpumping conditions, together with the other geophysical logs, indicate five transmissive fracture zones. More than 90 percent of the open-hole transmissivity is associated with a fracture zone 272 feet BLS (below land surface). A transmissive zone at 787 feet BLS that consists of nearly parallel fractures lies within the projected tunnel path; here the hydraulic head is 12 to 15 feet lower than that of transmissive zones above the 315-foot depth. The 60-megahertz directional borehole radar

  10. Analysis of surface wave propagation in a grounded dielectric slab covered by a resistive sheet

    NASA Technical Reports Server (NTRS)

    Shively, David G.

    1992-01-01

    Both parallel and perpendicular polarized surface waves are known to propagate on lossless and lossy grounded dielectric slabs. Surface wave propagation on a grounded dielectric slab covered with a resistive sheet is considered. Both parallel and perpendicular polarizations are examined. Transcendental equations are derived for each polarization and are solved using iterative techniques. Attenuation and phase velocity are shown for representative geometries. The results are applicable to both a grounded slab with a resistive sheet and an ungrounded slab covered on each side with a resistive sheet.

  11. Slab fluid release: localized in space and time

    NASA Astrophysics Data System (ADS)

    John, T.; Gussone, N. C.; Podladchikov, Y. Y.

    2012-12-01

    the amount of precipitated carbonate during flow. This indicates that some fraction of the slab fluid was liberated by sub-crustal dehydration, then transported over up to km scales within the overlying oceanic crust. Lithium chronometry is currently the tool of choice to obtain information on the duration of fluid flow and fluid-rock interaction. In a structure like our reaction selvage, the advective component of the element transport is focused into fracture-related porosity, e.g., into the vein. Consequently, for such a fluid-dominated system, element transport within unfractured rock adjacent to a fluid conduit is dominantly diffusive and can be treated as having resulted from bulk diffusion. Element transport occurs exclusively within the fluid-filled interconnected porosity and exchange with minerals occurs through dissolution-precipitation reactions. While the Ca isotopes indicate that intra slab fluid flow is highly channelized and that the released fluids travel through slabs along major conduits, Li-diffusion modeling shows that this fluid flow occurs in a pulse-like manner of less than ~200 years duration. This implies that even though the overall slab dehydration is a continuous process, dehydrating slabs release their fluid by short-lived, channelized fluid-flow events. Such pulses could feed arc magma sources with aqueous fluids, with these fluids traversing the slab-wedge interface in transient hydraulic fractures.

  12. Electromagnetic and ultrasonic investigations on a roman marble slab

    NASA Astrophysics Data System (ADS)

    Capizzi, Patrizia; Cosentino, Pietro L.

    2010-05-01

    The archaeological Museum of Rome (Museo delle Terme di Diocleziano) asked our group about the physical consistency of a marble slab (II - III century AD) that has recently fallen down during the transportation for an exhibition. In fact, due to insurance conflict, it was necessary to control the new fractures due to the recent accident and distinguish them from the ancient ones. The sculptured slab (today's size is 1280 x 70 x 9 cm), cut at the ends for a re-use as an inscription in the rear face, was restored (assemblage of different broken parts and cleaning) in contemporary times. We used different methodologies to investigate the slab: namely a pacometer (Protovale Elcometer) to individuate internal coupling pins, GPR (2000 MHz) and Ultrasonic (55 kHz) tomographic high-density surveys to investigate the internal extension of all the visible fractures and to search for the unknown internal ones. For every methodology used the quality of the acquired data was relatively high. They have been processed and compared to give a set of information useful for the bureaucratic problems of the Museum. Later on, the data have been processed in depth, for studying how to improve the data processing and for extracting all the information contained in the whole set of experimental data. Finally, the results of such a study in depth are exposed in detail.

  13. OSTEOSYNTHESIS OF PROXIMAL HUMERAL END FRACTURES WITH FIXED-ANGLE PLATE AND LOCKING SCREWS: TECHNIQUE AND RESULTS

    PubMed Central

    Cohen, Marcio; Amaral, Marcus Vinicius; Monteiro, Martim; Brandão, Bruno Lobo; Motta Filho, Geraldo Rocha

    2015-01-01

    Describe the results of proximal humeral fractures surgically treated with the Philos locking plate system. Method: Between March 2003 and October 2004 we prospectively reviewed 24 of 26 patients with proximal humerus fractures treated with a Philos plate. The mean follow-up time was 12 months and the mean age of patients was 57 years. Six patients had four-part proximal humerus fractures, 11 patients had three-part proximal humerus fractures, and nine patients had two-part proximal humerus fractures. Clinical evaluation was performed using the University of California at Los Angeles (UCLA) criteria. Results: The mean UCLA score was 30 points (17-34). All fractures showed union. Three patients showed fracture union at varus position. The mean UCLA score for these patients was 27 points. Conclusion: Osteosynthesis with Philos plate provides a stable fixation method with good functional outcome. PMID:26998460

  14. Maxus challenges fracture techniques, brings in the best wells in 20 years

    SciTech Connect

    Lyle, D.

    1995-10-01

    Combining a look at old ideas and new techniques gave Maxus a string of better Texas Panhandle wells. This report describes the results of an analysis performed utilizing the program FRACPRO which has real time analysis capabilities. The analysis indicated poor proppant placement.

  15. Mechanical Consequences of Metamorphism and Their Effects on In-slab Earthquakes

    NASA Astrophysics Data System (ADS)

    Wang, K.; Kao, H.; Cassidy, J. F.; Wada, I.

    2004-05-01

    The relatively few earthquakes deeper inside a subducting slab tend to have larger magnitudes than those just below the slab surface. For example, three recent damaging events (1999 Oaxaca, Mexico; 2001 Geiyo, Nankai; 2001 Nisqually, Cascadia) in warm slabs all occurred in the lower crust or mantle. We propose that this is controlled by slab metamorphic processes. The metabasalt-eclogite transformation of the subducting oceanic crust causes up to 15% volume reduction. Because of temperature and kinetics, the densification begins in a thin layer along the top of the slab. Volume reduction gives rise to an equivalent stretching force in the thin layer in all slab-parallel directions, activating existing faults and developing new fractures. The theory of fracture spacing predicts that the densified thin layer must be "shattered". The shattered upper crust may have numerous small earthquakes but does not favor large ruptures. In contrast, the much more uniform lower crust and mantle can host larger ruptures, although seismic ruptures may occur only in limited hydrated parts. Earthquakes that rupture the subducting mantle, such as the M 6.8 2001 Nisqually earthquake at Cascadia, appear to require serpentine dehydration along pre-existing deep faults.

  16. Mantle flow and dynamic topography associated with slab window opening

    NASA Astrophysics Data System (ADS)

    Guillaume, Benjamin; Moroni, Monica; Funiciello, Francesca; Martinod, Joseph; Faccenna, Claudio

    2010-05-01

    A slab window is defined as an 'hole' in the subducting lithosphere. In the classical view, slab windows develop where a spreading ridge intersects a subduction zone. The main consequences of this phenomenon are the modifications of the physical, chemical and thermal conditions in the backarc mantle that in turn affect the tectonic and magmatic evolution of the overriding plate. In this work, we perform dynamically self-consistent mantle-scale laboratory models, to evaluate how the opening of a window in the subducting panel influences the geometry and the kinematics of the slab, the mantle circulation pattern and, finally, the overriding plate dynamic topography. The adopted setup consists in a two-layer linearly viscous system simulating the roll-back of a fixed subducting plate (simulated using silicone putty) into the upper mantle (simulated using glucose syrup). Our experimental setting is also characterized by a constant-width rectangular window located at the center of a laterally confined slab, modeling the case of the interaction of a trench-parallel spreading ridge with a wide subduction zone. We find that the geometry and the kinematics of the slab are only minorly affected by the opening of a slab window. On the contrary, slab induced mantle circulation, quantified using Feature Tracking image analysis technique, is strongly modified and produces a peculiar non-isostatic topographic signal on the overriding plate. Assuming that our modeling results can be representative of the natural behavior of subduction zones, we compare them to the Patagonian subduction zone finding that anomalous backarc volcanism that developed since middle Miocene could result from the lateral flowage of subslab mantle, and that part of the Patagonian uplift could be dynamically supported.

  17. Biomechanical Evaluation of Interfragmentary Compression At Tibia Plateau Fractures In Vitro Using Different Fixation Techniques: A CONSORT-Compliant Article: Erratum.

    PubMed

    2015-02-01

    [In the article "Biomechanical Evaluation of Interfragmentary Compression At Tibia Plateau Fractures In Vitro Using Different Fixation Techniques: A CONSORT-compliant" article, which appeared in Volume 94, Issue 1 of Medicine, a line denoting dual authorship was omitted. K. Kojima and B. Gueorguiev contributed equally to the article.].

  18. Biomechanical study in polyurethane mandibles of different metal plates and internal fixation techniques, employed in mandibular angle fractures.

    PubMed

    Semeghini Guastaldi, Fernando Pozzi; Hochuli-Vieira, Eduardo; Guastaldi, Antonio Carlos

    2014-11-01

    The aim of this study was to perform a physicochemical and morphological characterization and compare the mechanical behavior of an experimental Ti-Mo alloy to the analogous metallic Ti-based fixation system, for mandibular angle fractures. Twenty-eight polyurethane mandibles were uniformly sectioned on the left angle. These were divided into 4 groups: group Eng 1P, one 2.0-mm plate and 4 screws 6 mm long; group Eng 2P, two 2.0-mm plates, the first fixed with 4 screws 6 mm long and the second with 4 screws 12 mm long. The same groups were created for the Ti-15Mo alloy. Each group was subjected to linear vertical loading at the first molar on the plated side in a mechanical testing unit. Means and standard deviations were compared with respect to statistical significance using ANOVA. The chemical composition of the Ti-15Mo alloy was close to the nominal value. The mapping of Mo and Ti showed a homogeneous distribution. SEM of the screw revealed machining debris. For the plates, only the cpTi plate undergoes a surface treatment. The metallographic analysis reveals granular microstructure, from the thermomechanical trials. A statistically significant difference was found (P < 0.05) when the comparison between both internal fixation techniques was performed. The 2P technique showed better mechanical behavior than 1P. PMID:25340696

  19. How mantle slabs drive plate tectonics.

    PubMed

    Conrad, Clinton P; Lithgow-Bertelloni, Carolina

    2002-10-01

    The gravitational pull of subducted slabs is thought to drive the motions of Earth's tectonic plates, but the coupling between slabs and plates is not well established. If a slab is mechanically attached to a subducting plate, it can exert a direct pull on the plate. Alternatively, a detached slab may drive a plate by exciting flow in the mantle that exerts a shear traction on the base of the plate. From the geologic history of subduction, we estimated the relative importance of "pull" versus "suction" for the present-day plates. Observed plate motions are best predicted if slabs in the upper mantle are attached to plates and generate slab pull forces that account for about half of the total driving force on plates. Slabs in the lower mantle are supported by viscous mantle forces and drive plates through slab suction. PMID:12364804

  20. How mantle slabs drive plate tectonics.

    PubMed

    Conrad, Clinton P; Lithgow-Bertelloni, Carolina

    2002-10-01

    The gravitational pull of subducted slabs is thought to drive the motions of Earth's tectonic plates, but the coupling between slabs and plates is not well established. If a slab is mechanically attached to a subducting plate, it can exert a direct pull on the plate. Alternatively, a detached slab may drive a plate by exciting flow in the mantle that exerts a shear traction on the base of the plate. From the geologic history of subduction, we estimated the relative importance of "pull" versus "suction" for the present-day plates. Observed plate motions are best predicted if slabs in the upper mantle are attached to plates and generate slab pull forces that account for about half of the total driving force on plates. Slabs in the lower mantle are supported by viscous mantle forces and drive plates through slab suction.

  1. Reattachment of a fractured fragment with relined fiber post using indirect technique: a case report

    PubMed Central

    Kim, Eun-Soo; Min, Kyung-San; Yu, Mi-Kyung

    2014-01-01

    Although fiber-reinforced posts have been widely used, they sometimes fail to obtain sufficient retention because of an extremely large canal space. To address this, several techniques have been introduced including relining of the fiber-reinforced posts. Here, we used a relined glass-fiber post to increase retention and fitness to the root canal in a crown reattachment case. The relining procedure was performed by using an indirect method on the working cast. This case also highlights the esthetic concerns regarding dehydration of the attached crown fragment. PMID:25383353

  2. Elbow hemiarthroplasty for the management of distal humeral fractures: current technique, indications and results

    PubMed Central

    Watts, Adam C; Bain, Gregory I

    2016-01-01

    There has been a growing recent interest in the use of elbow hemiarthroplasty for the treatment of distal humeral trauma in select patients. However, the current available evidence regarding outcome after elbow hemiarthroplasty is limited to case series and biomechanical data. Consequently, the procedure remains unfamiliar to many surgeons. The aim of the present review is to outline the evidence regarding elbow hemiarthroplasty and to use this, along with the author’s experience, to better describe the indications, surgical technique and outcomes after this procedure. PMID:27583016

  3. Elbow hemiarthroplasty for the management of distal humeral fractures: current technique, indications and results.

    PubMed

    Phadnis, Joideep; Watts, Adam C; Bain, Gregory I

    2016-07-01

    There has been a growing recent interest in the use of elbow hemiarthroplasty for the treatment of distal humeral trauma in select patients. However, the current available evidence regarding outcome after elbow hemiarthroplasty is limited to case series and biomechanical data. Consequently, the procedure remains unfamiliar to many surgeons. The aim of the present review is to outline the evidence regarding elbow hemiarthroplasty and to use this, along with the author's experience, to better describe the indications, surgical technique and outcomes after this procedure. PMID:27583016

  4. Effects of triggering mechanism on snow avalanche slope angles and slab depths from field data

    NASA Astrophysics Data System (ADS)

    McClung, David M.

    2013-04-01

    Field data from snow avalanche fracture lines for slope angle and slab depth (measured perpendicular to the weak layer) were analyzed for different triggering mechanisms. For slope angle, the results showed that the same probability density function (pdf) (of log-logistic type) and range (25 - 55 degrees) apply independent of triggering mechanism. For slab depth, the same pdf (generalized extreme value) applies independent of triggering mechanism. For both slope angle and slab depth, the data skewness differentiated between triggering mechanism and increased with applied triggering load. For slope angle, skewness is lowest for natural triggering by snow loads and highest for triggering from human intervention. For slab depth, the skewness is lowest for natural triggering and highest for a mix of triggers including explosive control with skier triggering being intermediate. The results reveal the effects of triggering mechanism which are important for risk analyses and to guide avalanche forecasting.

  5. Optical distortions in end-pumped zigzag slab lasers.

    PubMed

    Tang, Bing; Zhou, Tangjian; Wang, Dan; Li, Mi

    2015-04-01

    Ray tracing is performed to investigate the optical distortions in the end-pumped, zigzag slab. Optical path differences caused by temperature, slab deformation, and stress birefringence are calculated under uniform pumping; the results show a steep edge in the width dimension and a thermal lens with an effective focal length as short as several meters in the thickness dimension. Dependence of depolarization on total internal reflection phase retardance as well as the slab's cut angle is studied by the Jones matrix technique; results show that although at the pumping power of 10 kW, the mean depolarization of the 2.5  mm×30  mm×150.2  mm Nd:YAG slab is generally below 3%, and it increases rapidly with pumping power. Besides, for the 0°- or 60°-cut slab, an optimal phase retardance range of 5° to 13° exists, in which the depolarization loss can be lower than 0.5%. Finally, experiments on temperature and depolarization measurements verify the numerical results. PMID:25967178

  6. Seismicity and structure in central Mexico: Evidence for a possible slab tear in the South Cocos plate

    NASA Astrophysics Data System (ADS)

    Dougherty, Sara L.; Clayton, Robert W.

    2014-04-01

    The morphology of the transition from flat to normal subduction in eastern central Mexico is explored using intraslab earthquakes recorded by temporary and permanent regional seismic arrays. Observations of a sharp transition in slab dip near the abrupt end of the Trans-Mexican Volcanic Belt (TMVB) suggest a possible slab tear located within the subducted South Cocos plate. The eastern lateral extent of a thin ultra-slow velocity layer (USL) imaged atop the Cocos slab in recent studies along the Meso America Subduction Experiment array is examined here using additional data. We find an end to this USL which is coincident with the western boundary of a zone of decreased seismicity and the end of the TMVB near the sharp transition in slab dip. Waveform modeling of the 2-D structure in this region using a finite difference algorithm provides constraints on the velocity and geometry of the slab's seismic structure and confirms the location of the USL. Analysis of intraslab seismicity patterns reveals clustering, sudden increase in depth, variable focal mechanism orientations and faulting types, and alignment of source mechanisms along the sharp transition in slab dip. The seismicity and structural evidence suggests a possible tear in the South Cocos slab. This potential tear, together with the tear along the Orozco Fracture Zone to the northwest, indicates a slab rollback mechanism in which separate slab segments move independently, allowing for mantle flow between the segments.

  7. DESIGN AND TESTING OF SUB-SLAB DEPRESSURIZATION FOR RADON MITIGATION IN NORTH FLORIDA HOUSES - PART I. PERFORMANCE AND DURABILITY - VOLUME 1. TECHNICAL REPORT

    EPA Science Inventory

    The report gives results of a demonstration/research project to evaluate sub-slab depressurization (SSD) techniques for radon mitigation in North Florida where the housing stock is primarily slab-on-grade and the sub-slab medium typically consists of native soil and sand. Objecti...

  8. DESIGN AND TESTING OF SUB-SLAB DEPRESSURIZATION FOR RADON MITIGATION IN NORTH FLORIDA HOUSES - PART I. PERFORMANCE AND DURABILITY - VOLUME 2. DATA APPENDICES

    EPA Science Inventory

    The report gives results of a demonstration/research project to evaluate sub-slab depressurization (SSD) techniques for radon mitigation in North Florida where the housing stock is primarily slab-on-grade and the sub-slab medium typically consists of native soil and sand. Objecti...

  9. Techniques for predicting the lifetimes of wave-swept macroalgae: a primer on fracture mechanics and crack growth.

    PubMed

    Mach, Katharine J; Nelson, Drew V; Denny, Mark W

    2007-07-01

    Biomechanical analyses of intertidal and shallow subtidal seaweeds have elucidated ways in which these organisms avoid breakage in the presence of exceptional hydrodynamic forces imposed by pounding surf. However, comparison of algal material properties to maximum hydrodynamic forces predicts lower rates of breakage and dislodgment than are actually observed. Why the disparity between prediction and reality? Most previous research has measured algal material properties during a single application of force, equivalent to a single wave rushing past an alga. In contrast, intertidal macroalgae may experience more than 8000 waves a day. This repeated loading can cause cracks - introduced, for example, by herbivory or abrasion - to grow and eventually cause breakage, yet fatigue crack growth has not previously been taken into account. Here, we present methods from the engineering field of fracture mechanics that can be used to assess consequences of repeated force imposition for seaweeds. These techniques allow quantification of crack growth in wave-swept macroalgae, a first step towards considering macroalgal breakage in the realistic context of repeated force imposition. These analyses can also be applied to many other soft materials.

  10. Treatment of close-range, low-velocity gunshot fractures of tibia and femur diaphysis with consecutive compression-distraction technique: a report of 11 cases.

    PubMed

    Ateşalp, A Sabri; Kömürcü, Mahmut; Demiralp, Bahtiyar; Bek, Dogan; Oğuz, Erbil; Yanmiş, Ibrahim

    2004-01-01

    Lower extremity injuries secondary to close-range, low-velocity gunshot wounds are frequently seen in both civilian and military populations. A close-range, low-velocity injury produces high energy and often results in comminuted and complicated fractures with significant morbidity. In this study, four femoral, four tibial, and three combined tibia and fibular comminuted diaphyseal fractures secondary to close-range, low-velocity gunshot wounds in 11 military personnel were treated with debridement followed by compression-distraction lengthening using a circular external fixator frame. Fracture union was obtained in all without significant major complications. Fracture consolidation occurred at a mean of 3.5 months. At follow-up of 46.8 months, there were no delayed unions, nonunions, or malunions. Minor complications included four pin-tract infections and knee flexion limitation in two femur fractures. Osteomyelitis and deep soft tissue infection were not observed. This technique provided an alternative to casting, open reduction internal fixation, or intermedullary fixation with an acceptable complication rate.

  11. The effect of amount of lost tooth structure and restorative technique on fracture resistance of endodontically treated premolars

    PubMed Central

    Bassir, Mahshid Mohammadi; Labibzadeh, Akram; Mollaverdi, Fatemeh

    2013-01-01

    Aim: Endodontic treatment generally reduces the fracture resistance of teeth. The purpose of this study was to evaluate the fracture resistance and the mode of fracture of endodontically treated human premolars with different amounts of remaining tooth structure. Materials and Methods: Seventy non-carious human premolars were randomly assigned into 7 groups. Group 1 (ST) did not receive any preparation. The teeth in groups 2-7 received root canal treatment and different preparations. Group 2 (MO-NF): Mesio-occlusal preparation without filling; Group 3 (MOD-NF): Mesio-occluso-distal preparation without filling; Group 4 (MO-F): Mesio-occlusal preparation with direct composite restoration (Z250); Group 5 (MOD-F): Mesio-occluso-distal preparation with direct composite restoration (Z250); Group 6 (CC-D): Mesio-occluso-distal preparation with cusp reduction and direct composite restoration (Z250); Group 7 (CC-InD): Mesio-occluso-distal preparation with cusp reduction and indirect composite restoration (Gradia GC). The fracture resistance (N) was assessed under compressive load in a universal testing machine (Zwick) perpendicular to the occlusal surface at a cross-head speed of 1 mm/min, and the mode of fracture was assessed under stereomicroscope. Statistical analysis: Data was analyzed by Kruskal – Wallis and Mann – Whitney tests and the mode of fracture was analyzed by Chi-square test (P < 0.05). Results: Statistical analysis showed that MO and MOD cavity preparations significantly reduced the fracture resistance of sound teeth. Direct composite restorations can improve the fracture resistance, and Groups 7 and 6 presented the highest fracture resistance values. Conclusions: Teeth with adhesive restorations showed significantly higher fracture resistance values as compared with the non-restored ones. PMID:24082569

  12. Comparative Evaluation of Fracture Resistance of Root Obturated with Resilon and Gutta-Percha Using Two Different Techniques: An in Vitro Study

    PubMed Central

    Shiraguppi, Vijayakumar L.; Shivalingappa, Chandu Giriyapur; Desai, Niranjan; Azad, Antriksh

    2015-01-01

    Introduction: Present study evaluated the fracture resistance of endodontically treated teeth filled with Gutta percha and a new resin based obturating material (Resilon). Materials and Methods: A total of 150 freshly extracted Mandibular premolar with fully formed apices were selected and decoronated at cemento-enamel junction (CEJ). Teeth were divided into Group A and Group B of 75 teeth each. In Group A canals were prepared up to # no 40 K file and Group B up to #no 80 K file. Both the groups were sub divided into five group of 15 teeth each as control group (unfilled canals), lateral condensation with Gutta-percha using AH 26 sealer, vertical condensation with Gutta-percha using AH 26 sealer, lateral condensation with Resilon using resilon sealer, vertical condensation with Resilon using resilon sealer. Each specimen was subjected to compressive load using Universal testing machine. The force required to fracture was recorded and data were analysed by ANOVA, Duncan’s test and student T test. Result: The result showed that there is statistically significant difference among experimental groups (p < 0.05). The groups with the Resilon material displayed higher mean fracture loads than the Gutta percha groups. No statistically significant differences were observed between different preparation techniques. Conclusion: Obturating the canals with the new resin-based obturation material increases the in vitro fracture resistance of endodontically treated teeth when compared with standard Gutta percha techniques. PMID:25954697

  13. Surgical Fixation of Sternal Fractures: Preoperative Planning and a Safe Surgical Technique Using Locked Titanium Plates and Depth Limited Drilling

    PubMed Central

    Schulz-Drost, Stefan; Oppel, Pascal; Grupp, Sina; Schmitt, Sonja; Carbon, Roman Th.; Mauerer, Andreas; Hennig, Friedrich F.; Buder, Thomas

    2015-01-01

    Different ways to stabilize a sternal fracture are described in literature. Respecting different mechanisms of trauma such as the direct impact to the anterior chest wall or the flexion-compression injury of the trunk, there is a need to retain each sternal fragment in the correct position while neutralizing shearing forces to the sternum. Anterior sternal plating provides the best stability and is therefore increasingly used in most cases. However, many surgeons are reluctant to perform sternal osteosynthesis due to possible complications such as difficulties in preoperative planning, severe injuries to mediastinal organs, or failure of the performed method. This manuscript describes one possible safe way to stabilize different types of sternal fractures in a step by step guidance for anterior sternal plating using low profile locking titanium plates. Before surgical treatment, a detailed survey of the patient and a three dimensional reconstructed computed tomography is taken out to get detailed information of the fracture’s morphology. The surgical approach is usually a midline incision. Its position can be described by measuring the distance from upper sternal edge to the fracture and its length can be approximated by the summation of 60 mm for the basis incision, the thickness of presternal soft tissue and the greatest distance between the fragments in case of multiple fractures. Performing subperiosteal dissection along the sternum while reducing the fracture, using depth limited drilling, and fixing the plates prevents injuries to mediastinal organs and vessels. Transverse fractures and oblique fractures at the corpus sterni are plated longitudinally, whereas oblique fractures of manubrium, sternocostal separation and any longitudinally fracture needs to be stabilized by a transverse plate from rib to sternum to rib. Usually the high convenience of a patient is seen during follow up as well as a precise reconstruction of the sternal morphology. PMID

  14. Study on the Multi-phase Flow and Fluid Saturation in 2D Fractured Media by Light Transmission Technique

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Ye, S.; Wu, J.

    2013-12-01

    Immiscible two-phase flows in fractured media are encountered in many engineering processes such as recovery of oil and gas, exploitation of geothermal energy, and groundwater contamination by immiscible chemicals. A two-dimensional rough wall parallel plate fracture model was set up and light transmission method (LTM) was applied to study two-phase flow system in fractured media. The fracture model stood with up and bottom flow and no flow on other two sides. A charge-coupled device (CCD) camera was used to monitor the migration of DNAPL and gas bubbles in the fracture model. To simulate two-phase system in fracture media, air was injected into the water saturated cell (C1) through the middle of the bottom and NAPL was injected into another water saturated cell (C2) through the middle of the top of the cell. The results show LTM was an effective way in monitoring the migration of DNAPL and gas bubbles in the fracture models. Gas moved upwards quickly to the top of C1 in the way of air bubbles generated at the injection position and formed a continuous distribution. The migration of TCE was controlled by its own weight and fracture aperture. TCE migrated to large aperture firstly when moving downwards, and intruded into smaller one with accumulation of TCE. Light Intensity-Saturation Models (LISMs) were developed to estimate the gas or NAPL saturation in two-phase system. The volume amount of infiltration of gas bubbles or NAPL could be estimated from light intensities by LISMs. There were strong correlations between the added and calculated amounts of gas or TCE. It is feasible to use the light transmission method to characterize the movement and spatial distribution of gas or NAPL in fractured media.

  15. Mantle flow and dynamic topography associated with slab window opening: Insights from laboratory models

    NASA Astrophysics Data System (ADS)

    Guillaume, Benjamin; Moroni, Monica; Funiciello, Francesca; Martinod, Joseph; Faccenna, Claudio

    2010-12-01

    We present dynamically self-consistent mantle-scale laboratory models that have been conducted to improve our understanding of the influence of slab window opening on subduction dynamics, mantle flow and associated dynamic topography over geological time scales. The adopted setup consists of a two-layer linearly viscous system simulating the subduction of a fixed plate of silicone (lithosphere) under negative buoyancy in a viscous layer of glucose syrup (mantle). Our experimental setting is also characterized by a constant-width rectangular window located at the center of a laterally confined slab, modeling the case of the interaction of a trench-parallel spreading ridge with a wide subduction zone. We found that the opening of a slab window does not produce consistent changes of the geometry and the kinematics of the slab. On the contrary, slab-induced mantle circulation, quantified both in the vertical and horizontal sections using the Feature Tracking image analysis technique, is strongly modified. In particular, rollback subduction and the opening of the slab window generate a complex mantle circulation pattern characterized by the presence of poloidal and toroidal components, with the importance of each evolving according to kinematic stages. Mantle coming from the oceanic domain floods through the slab window, indenting the supra-slab mantle zone and producing its deformation without any mixing between mantle portions. The opening of the slab window and the upwelling of sub-slab mantle produce a regional-scale non-isostatic topographic uplift of the overriding plate that would correspond to values ranging between ca. 1 and 5 km in nature. Assuming that our modeling results can be representative of the natural behavior of subduction zones, we compared them to the tectonics and volcanism of the Patagonian subduction zone. We found that the anomalous backarc volcanism that has been developing since the middle Miocene could result from the lateral flow of sub-slab

  16. Retropatellar nailing and condylar bolts for complex fractures of the tibial plateau: technique, pilot study and rationale.

    PubMed

    Garnavos, Christos

    2014-07-01

    In a previous study, condylar compression bolts and intramedullary nailing with the use of a traditional transpatellar tendon approach were employed for the management of non-impacted complex fractures of the tibia plateau. However, there were intra-operative difficulties, related to the surgical approach that could jeopardise fracture reduction and contribute to sub-optimal outcomes. The purpose of this study is to introduce the retropatellar approach for the management of complex tibial plateau fractures with intramedullary nailing and condylar compression bolts that avoid the pitfalls created by the traditional transpatellar approach.

  17. Electromagnetic and ultrasonic investigations on a Roman marble slab

    NASA Astrophysics Data System (ADS)

    Capizzi, P.; Cosentino, P. L.

    2011-09-01

    The archaeological museum of Rome asked our group about the physical consistency of a marble slab (second to third century AD) that recently fell during its travel as part of an exhibition. We decided to use different methodologies to investigate the slab: namely a pacometer (Protovale Elcometer) to individuate the internal coupling pins, and ground-penetrating radar (GPR) (2000 MHz) and ultrasonic (55 kHz) tomographic high-density surveys to investigate the internal extension of all the visible fractures and to search for the hidden ones. For the ultrasonic data, tests were carried out to optimize the inversion parameters, in particular the cell dimensions. Surely, the choice of cell size for the inversion process must take into account the size of the acquisition grid and the ray number acquired. We proposed to calculate a minimum Fresnel's radius using the sampling frequency instead of that of the probes. For every methodology used, the quality of the acquired data was relatively high. This was then processed and compared to provide information that was useful for some of the insurance problems of the museum. Later on, the data was processed in depth to see how to improve the data processing and interpretation. Finally, the results of this in-depth study were exposed in detail. Ultrasonic and GPR tomographies show a strong correlation, and in particular, the inhomogeneous areas are located in correspondence to the slab injuries.

  18. All-polymer photonic crystal slab sensor.

    PubMed

    Hermannsson, Pétur G; Sørensen, Kristian T; Vannahme, Christoph; Smith, Cameron L C; Klein, Jan J; Russew, Maria-Melanie; Grützner, Gabi; Kristensen, Anders

    2015-06-29

    An all-polymer photonic crystal slab sensor is presented, and shown to exhibit narrow resonant reflection with a FWHM of less than 1 nm and a sensitivity of 31 nm/RIU when sensing media with refractive indices around that of water. This results in a detection limit of 4.5 × 10(-6) RIU when measured in conjunction with a spectrometer of 12 pm/pixel resolution. The device is a two-layer structure, composed of a low refractive index polymer with a periodically modulated surface height, covered with a smooth upper-surface high refractive index inorganic-organic hybrid polymer modified with ZrO2based nanoparticles. Furthermore, it is fabricated using inexpensive vacuum-less techniques involving only UV nanoreplication and polymer spin-casting, and is thus well suited for single-use biological and refractive index sensing applications. PMID:26191664

  19. Infraorbital nerve transpositioning into orbital floor: a modified technique to minimize nerve injury following zygomaticomaxillary complex fractures

    PubMed Central

    Kotrashetti, Sharadindu Mahadevappa; Kale, Tejraj Pundalik; Bhandage, Supriya

    2015-01-01

    Objectives Transpositioning of the inferior alveolar nerve to prevent injury in lower jaw has been advocated for orthognathic, pre-prosthetic and for implant placement procedures. However, the concept of infra-orbital nerve repositioning in cases of mid-face fractures remains unexplored. The infraorbital nerve may be involved in trauma to the zygomatic complex which often results in sensory disturbance of the area innervated by it. Ten patients with infraorbital nerve entrapment were treated in similar way at our maxillofacial surgery centre. Materials and Methods In this article we are reporting three cases of zygomatico-maxillary complex fracture in which intra-operative repositioning of infra-orbital nerve into the orbital floor was done. This was done to release the nerve from fractured segments and to reduce the postoperative neural complications, to gain better access to fracture site and ease in plate fixation. This procedure also decompresses the nerve which releases it off the soft tissue entrapment caused due to trauma and the organized clot at the fractured site. Results There was no evidence of sensory disturbance during their three month follow-up in any of the patient. Conclusion Infraorbital nerve transposition is very effective in preventing paresthesia in patients which fracture line involving the infraorbital nerve. PMID:25922818

  20. Block-slider model for ductile instabilities in subducting slabs

    NASA Astrophysics Data System (ADS)

    Riedel, M. R.

    2003-04-01

    It has been suggested that the occurence of ductile (or plastic) instabilities in the deeper portion of subducting slabs is the dominating mechanism for the generation of intermediate-depth and deep-focus earthquakes. Heat generated during viscous deformation provides a positive feedback to creep and eventually faulting under high pressure. Recent detailed receiver function images of the structure of the Japan subduction zone seem to provide support for this notion. First, there is no indication of an existing metastable olivine wedge. Second, the intermediate-depth seismicity seems to be located in the strong and colder portions of the downgoing slab, about 30 km below the oceanic Moho. This suggests that instead of dehydration or phase transformation triggered events, ductile faulting is its predominating cause. In a recent paper, we have discussed the necessary conditions for ductile instabilities to develop in the bended subducting mantle lithosphere, based on the available experimental data on viscous creep of olivine resp. spinel (*). The present paper aims at a numerical study of the time evolution of a nucleated instability. For this purpose, we develop a cellular block-slider model for ductile instabilities in the mantle lithosphere, in analogy to the frequently used and highly successful block-slider models for brittle fracture of the crust. The block-slider approach is numerically much less demanding than solutions based on the corresponding, thermal-mechanically coupled continuum equations. Furthermore, it allows a straightforward inclusion of possible non-equilibrium effects associated with mineral phase transformations in a subducting slab (kinetic overshoot, grainsize reduction). The obtained numerical results are compared with seismological observation. It is shown, e.g., that the existence of metastable olivine in the deeper portion of a slab (below 500 km) is not a necessary condition for the generation of deep-focus earthquakes. (*) S. Karato, M

  1. Tethyan subducted slabs under India

    NASA Astrophysics Data System (ADS)

    Van der Voo, Rob; Spakman, Wim; Bijwaard, Harmen

    1999-08-01

    Tomographic imaging of the mantle under Tibet, India and the adjacent Indian Ocean reveals several zones of relatively high P-wave velocities at various depths. Under the Hindu Kush region in northeastern Afghanistan and southern Tajikistan, a regional northward-dipping slab is seen in the entire upper 600 km of the mantle and is apparently still attached to the lithosphere of the Indian plate. Under northern Pakistan this same slab shows a roll-over structure with the deeper portion overturned and dipping southward, as can also be seen in the distribution of earthquake hypocenters. Farther east-southeast (e.g., in the vicinity of Nepal), a well-resolved anomaly below 450 km depth is connected to the slab under the Hindu Kush, but seems to be separated from the lithosphere above 350 km. These upper-mantle anomalies are interpreted as the remnants of delaminated sub-continental lithosphere that went down when Greater India continued to converge northward with Asia after ˜45 Ma. The deeper high-velocity anomalies under the Indian sub-continent appear clearly separated from the shallower ones as well as from each other, and are inferred to represent remnants of oceanic lithospheric slabs that have sunk into the lower mantle and were subsequently overridden by the Indian plate. They occur at depths between 1000 and 2300 km and occasionally descend down to the core-mantle boundary. The anomalies form three parallel WNW-ESE striking zones. We interpret the two southern zones as remnants of oceanic lithosphere that was subducted when the Neo-Tethys Ocean closed between India and Tibet in the Cretaceous and earliest Tertiary. The northern deep-mantle zone under northern Afghanistan, the Himalayas and the Lhasa block in southern Tibet may represent the last-subducted remnant of the Paleo-Tethys Ocean, which is thought to have closed before the Hauterivian stage of the Early Cretaceous. The middle zone continues southeastward as a rather straight high-velocity zone towards

  2. Comparative Evaluation of Fracture Resistance of Endodontically Treated Teeth Obturated with Resin Based Adhesive Sealers with Conventional Obturation Technique: An In vitro Study

    PubMed Central

    Langalia, Akshay K; Dave, Bela; Patel, Neeta; Thakkar, Viral; Sheth, Sona; Parekh, Vaishali

    2015-01-01

    Background: To compare fracture resistance of endodontically treated teeth obturated with different resin-based adhesive sealers with a conventional obturation technique. Materials and Methods: A total of 60 Single canaled teeth were divided into five groups. The first group was taken as a negative control. The rest of the groups were shaped using ProFile rotary files (Dentsply Maillefer, Ballaigues, Switzerland). The second group was obturated with gutta-percha and a ZOE-based sealer Endoflas FS (Sanlor Dental Products, USA). The third group was obturated with gutta-percha and an epoxy-based sealer AH Plus (Dentsply, DeTrey, Germany). The fourth group was obturated with Resilon (Pentron Clinical Technologies, Wallingford, CT) and RealSeal sealer (Pentron Clinical Technologies). The fifth group was obturated with EndoREZ points and EndoREZ sealer (both from Ultradent, South Jordan, UT). Roots were then embedded into acrylic blocks and were then fixed into a material testing system and loaded with a stainless steel pin with a crosshead speed of 5 mm/min until fracture. The load at which the specimen fractured was recorded in Newtons. Results: It was found that forces at fracture were statistically significant for the newer resin systems, Resilon, and EndoREZ. Conclusion: It was concluded that roots obturated with newer resin systems (Resilon and EndoREZ) enhanced the root strength almost up to the level of the intact roots. PMID:25859099

  3. Tears in subducting slabs: Examples from central Mexico and southern Peru

    NASA Astrophysics Data System (ADS)

    Dougherty, S. L.; Clayton, R. W.

    2013-12-01

    Slab tears are tectonically important morphological features of subducted plates that have been proposed to occur in numerous subduction zones. We examine the transitions from flat to normal subduction that occur in central Mexico and southern Peru for seismic evidence of such proposed tearing. The fine-scale seismic structure of these subduction zones is studied using moderate-sized (M4-6) intraslab earthquakes. Regional waveforms from temporary and permanent seismic arrays are complicated and contain detailed information about the subduction zone structure, including evidence of lateral heterogeneity, which is used to model the structure of the subducted plates. The lateral extent of a thin ultra-slow velocity layer (USL) imaged atop the Cocos slab in central Mexico in recent studies and evident atop the Nazca slab in southern Peru is mapped and examined for its relationship to the possible slab tears in each region. In central Mexico, there are two transitions from flat to normal subduction located in the west and east, respectively. In the west, recent tectonic studies have shown evidence for possible slab tearing along the projection of the Orozco Fracture Zone (OFZ), while in the east, observations of a sudden change in slab dip coupled with the abrupt end of the Trans Mexican Volcanic Belt (TMVB) suggest a second possible slab tear. In the west, we find an edge to the USL which is coincident with the western boundary of the projected OFZ region. Forward modeling of the 2D structure of the subducted Rivera and Cocos plates using a finite-difference algorithm provides constraints on the velocity and geometry of each slab's seismic structure in this region and confirms the location of the USL edge. Coupled with the results of recent plate motion studies showing that the Cocos plate moves differently on either side of the OFZ, we propose that the Cocos slab is currently fragmenting into a North Cocos plate and a South Cocos plate along the projection of the OFZ

  4. Retrograde Intramedullary Nailing with a Blocking Pin Technique for Reduction of Periprosthetic Supracondylar Femoral Fracture after Total Knee Arthroplasty: Technical Note with a Compatibility Chart of the Nail to Femoral Component

    PubMed Central

    Hamada, Daisuke; Takasago, Tomoya; Tsutsui, Takahiko; Suzue, Naoto; Sairyo, Koichi

    2014-01-01

    Periprosthetic fractures after total knee arthroplasty (TKA) present a clear management challenge, and retrograde intramedullary nails have recently gained widespread acceptance in treatment of these fractures. In two cases, we found a blocking screw technique, first reported by Krettek et al., was useful in the reduction of the fractures. Both patients attained preinjury mobility after intramedullary nailing. Moreover, we present a chart summarizing the notch designs of various femoral components because some prosthetic knee designs are not amenable to retrograde nailing. We hope this will be helpful in determining indications for retrograde nailing in periprosthetic fractures after TKA. PMID:25574411

  5. Perforation of thin unreinforced concrete slabs

    SciTech Connect

    Cargile, J.D.; Giltrud, M.E.; Luk, V.K.

    1993-10-01

    This report discusses fourteen tests which were conducted to investigate the perforation of thin unreinforced concrete slabs. The 4340-steel projectile used in the test series is 50.8 mm in diameter, 355.6 mm in length, has a mass of 2.34 kg. and an ogive nose with caliber radius head of 3. The slabs, contained within steel culverts, are 1.52 m in diameter and consist of concrete with a nominal unconfined compressive strength of 38.2 MPa and maxima aggregate size of 9.5 mm. Slab thicknesses are 284.4, 254.0, 215.9 and 127.0 mm. Tests were conducted at impact velocities of about 313 m/s on all slab thicknesses and about 379 and 471 m/s on the 254.0-mm-thick slab. All tests were conducted at normal incidence to the slab. All tests were conducted at normal incidence to the slab. Information obtained from the tests used to determine the loading (deceleration) on the projectile during the perforation process, the velocity-displacement of the projectile as it perforated the slab, and the projectile position as damage occurred on the backface of the slab. The test projectile behaved essentially as a rigid body for all of the tests.

  6. Evaluation of Stress Corrosion Cracking Susceptibility Using Fracture Mechanics Techniques, Part 1. [environmental tests of aluminum alloys, stainless steels, and titanium alloys

    NASA Technical Reports Server (NTRS)

    Sprowls, D. O.; Shumaker, M. B.; Walsh, J. D.; Coursen, J. W.

    1973-01-01

    Stress corrosion cracking (SSC) tests were performed on 13 aluminum alloys, 13 precipitation hardening stainless steels, and two titanium 6Al-4V alloy forgings to compare fracture mechanics techniques with the conventional smooth specimen procedures. Commercially fabricated plate and rolled or forged bars 2 to 2.5-in. thick were tested. Exposures were conducted outdoors in a seacoast atmosphere and in an inland industrial atmosphere to relate the accelerated tests with service type environments. With the fracture mechanics technique tests were made chiefly on bolt loaded fatigue precracked compact tension specimens of the type used for plane-strain fracture toughness tests. Additional tests of the aluminum alloy were performed on ring loaded compact tension specimens and on bolt loaded double cantilever beams. For the smooth specimen procedure 0.125-in. dia. tensile specimens were loaded axially in constant deformation type frames. For both aluminum and steel alloys comparative SCC growth rates obtained from tests of precracked specimens provide an additional useful characterization of the SCC behavior of an alloy.

  7. The effectiveness of the antegrade reamed technique: the experience and complications from 415 traumatic femoral shaft fractures

    PubMed Central

    Papadimitriou, George; Theodoratos, Gerasimos; Papanikolaou, Anastasios; Maris, John

    2009-01-01

    This retrospective study presents the experience gained through use of reamed femoral nails and reports results and respective complications. This study included 415 femur fractures (312 men and 101 women with a mean age of 27.8 years) that were treated from 1993 to 2004. The fractures were classified according to AO, and 74 open fractures were included and typed according to the Gustilo classification. Dynamic nailing was performed for nearly all type A fractures and static nailing for types B and C. After a mean follow-up of 1.5 years, union rate was 97.8%. The complications were: 9 non-unions, 14 delayed-unions, 4 torsional malunions, 6 limb length discrepancies (shortening) and 30 nerve pareses due to traction. Deep venous thrombosis (DVT) occurred below the knee in 4 patients, while there were recorded 3 pulmonary and 2 fat embolisms, 1 superficial and 1 deep infection. There were 28 broken screws identified postoperatively. Logistic regression analysis revealed that type B and C were associated with increased risk of complications, with respective odds ratios of 3.1 (95% CI = 1.3–7.2, P = 0.011) and 4.3 (95% CI = 1.8–10.3, P = 0.001) when compared to type A patterns. All patients returned to their activities in a mean time of 10 months. Intramedullary nailing is still the treatment of choice for femoral shaft fractures, but knowledge of potential complications and their association with certain fracture patterns is needed. PMID:19936887

  8. [Determination of torsion angle after shaft fractures of the lower extremity--clinical relevance and measurement techniques].

    PubMed

    Grützner, P; Hochstein, P; Simon, R; Wentzensen, A

    1999-03-01

    In the treatment of femoral and tibial fractures the frontal and sagittal planes are controlled and documented by conventional X-ray films. Computed tomography permits exact measurement of the coronal plane. Between June 1993 and December 1997, 161 computed tomographic measurements of femoral torsion and 55 of tibial torsion after shaft fracture were carried out. The results were analyzed in a clinical study. A CT examination was carried out if the clinical examination aroused suspicion of a difference in torsion. 28.5% of the patients examined with femoral fractures and 23.8% of those with tibial fractures and torsion differences of more than 20 degrees. Between June 1993 and June 1997, 30 corrective derotating osteotomies of the femur and 9 of the tibia were carried out. The average preoperative difference of torsion of the femur was 29 degrees and of the tibia 25 degrees. After the operation the average femur difference was 7 degrees and of the lower leg 6.5 degrees, which are inside normal physiological limits. The osteotomies were carried out in the metaphysis near the fracture. Additional corrections in other planes were necessary on the femur in 27% and on the lower leg in 46%. With the aim of avoiding torsion differences, or at least to recognize them at an early stage, CT measurements of torsion after osteosythetic treatment of fresh unilateral femur-shaft fractures were carried out in 49 patients between October 1996 and December 1997. The torsion measurements during the operations had to be carried out clinically. No sufficiently exact method of measurement is available in the operating room. Three patients with increased differences of 28 degrees, 26 degrees or 19 degrees had their osteosyntheses corrected. The measurements after correction were inside the normal spread.

  9. Subducting slabs: Jellyfishes in the Earth's mantle

    NASA Astrophysics Data System (ADS)

    Loiselet, Christelle; Braun, Jean; Husson, Laurent; Le Carlier de Veslud, Christian; Thieulot, Cedric; Yamato, Philippe; Grujic, Djordje

    2010-08-01

    The constantly improving resolution of geophysical data, seismic tomography and seismicity in particular, shows that the lithosphere does not subduct as a slab of uniform thickness but is rather thinned in the upper mantle and thickened around the transition zone between the upper and lower mantle. This observation has traditionally been interpreted as evidence for the buckling and piling of slabs at the boundary between the upper and lower mantle, where a strong contrast in viscosity may exist and cause resistance to the penetration of slabs into the lower mantle. The distribution and character of seismicity reveal, however, that slabs undergo vertical extension in the upper mantle and compression near the transition zone. In this paper, we demonstrate that during the subduction process, the shape of low viscosity slabs (1 to 100 times more viscous than the surrounding mantle) evolves toward an inverted plume shape that we coin jellyfish. Results of a 3D numerical model show that the leading tip of slabs deform toward a rounded head skirted by lateral tentacles that emerge from the sides of the jellyfish head. The head is linked to the body of the subducting slab by a thin tail. A complete parametric study reveals that subducting slabs may achieve a variety of shapes, in good agreement with the diversity of natural slab shapes evidenced by seismic tomography. Our work also suggests that the slab to mantle viscosity ratio in the Earth is most likely to be lower than 100. However, the sensitivity of slab shapes to upper and lower mantle viscosities and densities, which remain poorly constrained by independent evidence, precludes any systematic deciphering of the observations.

  10. Subducting Slabs: Jellyfishes in the Earth's Mantle

    NASA Astrophysics Data System (ADS)

    Loiselet, C.; Braun, J.; Husson, L.; Le Carlier de Veslud, C.; Thieulot, C.; Yamato, P.; Grujic, D.

    2010-12-01

    The constantly improving resolution of geophysical data, seismic tomography and seismicity in particular, shows that the lithosphere does not subduct as a slab of uniform thickness but is rather thinned in the upper mantle and thickened around the transition zone between the upper and lower mantle. This observation has traditionally been interpreted as evidence for the buckling and piling of slabs at the boundary between the upper and lower mantle, where a strong contrast in viscosity may exist and cause resistance to the penetration of slabs into the lower mantle. The distribution and character of seismicity reveal, however, that slabs undergo vertical extension in the upper mantle and compression near the transition zone. In this paper, we demonstrate that during the subduction process, the shape of low viscosity slabs (1 to 100 times more viscous than the surrounding mantle) evolves toward an inverted plume shape that we coin jellyfish. Results of a 3D numerical model show that the leading tip of slabs deform toward a rounded head skirted by lateral tentacles that emerge from the sides of the jellyfish head. The head is linked to the body of the subducting slab by a thin tail. A complete parametric study reveals that subducting slabs may achieve a variety of shapes, in good agreement with the diversity of natural slab shapes evidenced by seismic tomography. Our work also suggests that the slab to mantle viscosity ratio in the Earth is most likely to be lower than 100. However, the sensitivity of slab shapes to upper and lower mantle viscosities and densities, which remain poorly constrained by independent evidence, precludes any systematic deciphering of the observations.

  11. Talus fractures: surgical principles.

    PubMed

    Rush, Shannon M; Jennings, Meagan; Hamilton, Graham A

    2009-01-01

    Surgical treatment of talus fractures can challenge even the most skilled foot and ankle surgeon. Complicated fracture patterns combined with joint dislocation of variable degrees require accurate assessment, sound understanding of principles of fracture care, and broad command of internal fixation techniques needed for successful surgical care. Elimination of unnecessary soft tissue dissection, a low threshold for surgical reduction, liberal use of malleolar osteotomy to expose body fracture, and detailed attention to fracture reduction and joint alignment are critical to the success of treatment. Even with the best surgical care complications are common and seem to correlate with injury severity and open injuries. PMID:19121756

  12. Influence of core design, production technique, and material selection on fracture behavior of yttria-stabilized tetragonal zirconia polycrystal fixed dental prostheses produced using different multilayer techniques: split-file, over-pressing, and manually built-up veneers

    PubMed Central

    Mahmood, Deyar Jallal Hadi; Linderoth, Ewa H; Wennerberg, Ann; Vult Von Steyern, Per

    2016-01-01

    Aim To investigate and compare the fracture strength and fracture mode in eleven groups of currently, the most commonly used multilayer three-unit all-ceramic yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) fixed dental prostheses (FDPs) with respect to the choice of core material, veneering material area, manufacturing technique, design of connectors, and radii of curvature of FDP cores. Materials and methods A total of 110 three-unit Y-TZP FDP cores with one intermediate pontic were made. The FDP cores in groups 1–7 were made with a split-file design, veneered with manually built-up porcelain, computer-aided design-on veneers, and over-pressed veneers. Groups 8–11 consisted of FDPs with a state-of-the-art design, veneered with manually built-up porcelain. All the FDP cores were subjected to simulated aging and finally loaded to fracture. Results There was a significant difference (P<0.05) between the core designs, but not between the different types of Y-TZP materials. The split-file designs with VITABLOCS® (1,806±165 N) and e.max® ZirPress (1,854±115 N) and the state-of-the-art design with VITA VM® 9 (1,849±150 N) demonstrated the highest mean fracture values. Conclusion The shape of a split-file designed all-ceramic reconstruction calls for a different dimension protocol, compared to traditionally shaped ones, as the split-file design leads to sharp approximal indentations acting as fractural impressions, thus decreasing the overall strength. The design of a framework is a crucial factor for the load bearing capacity of an all-ceramic FDP. The state-of-the-art design is preferable since the split-file designed cores call for a cross-sectional connector area at least 42% larger, to have the same load bearing capacity as the state-of-the-art designed cores. All veneering materials and techniques tested in the study, split-file, over-press, built-up porcelains, and glass–ceramics are, with a great safety margin, sufficient for clinical use

  13. The slab geometry laser. I - Theory

    NASA Technical Reports Server (NTRS)

    Eggleston, J. M.; Kane, T. J.; Kuhn, K.; Byer, R. L.; Unternahrer, J.

    1984-01-01

    Slab geometry solid-state lasers offer significant performance improvements over conventional rod-geometry lasers. A detailed theoretical description of the thermal, stress, and beam-propagation characteristics of a slab laser is presented. The analysis includes consideration of the effects of the zig-zag optical path, which eliminates thermal and stress focusing and reduces residual birefringence.

  14. Slab Houses: Reflections of the Past.

    ERIC Educational Resources Information Center

    Cappetta, Ann

    1990-01-01

    Describes how students, influenced by Victorian architecture, created ceramic slab houses. Students devised a solution to depict the reflective nature of Victorian bay windows. Project incorporates art history, handbuilding, and surface ornamentation. Outlines and illustrates steps involved in making slab houses that can be adapted for use by…

  15. Investigation of the influence of mallet and chisel techniques on the lingual fracture line and comparison with the use of splitter and separators during sagittal split osteotomy in cadaveric pig mandibles.

    PubMed

    Verweij, Jop P; Mensink, Gertjan; Houppermans, Pascal N W J; Frank, Michael D; van Merkesteyn, J P Richard

    2015-04-01

    In bilateral sagittal split osteotomy the proximal and distal segments of the mandible are traditionally separated using chisels. Modern modifications include prying and spreading the segments with splitters. This study investigates the lingual fracture patterns and status of the nerve after sagittal split osteotomy (SSO) using the traditional chisel technique and compares these results with earlier studies using the splitter technique. Lingual fractures after SSO in cadaveric pig mandibles were analysed using a lingual split scale and split scoring system. Iatrogenic damage to the inferior alveolar nerve was assessed. Fractures started through the caudal cortex more frequently in the chisel group. This group showed more posterior lingual fractures, although this difference was not statistically significant. Nerve damage was present in three cases in the chisel group, but was not observed in the splitter group. A trend was apparent, that SSO using the chisel technique instead of the splitter technique resulted in more posterior lingual fracture lines, although this difference was not statistically significant. Both techniques resulted in reliable lingual fracture patterns. Splitting without chisels could prevent nerve damage, therefore we propose a spreading and prying technique with splitter and separators. However, caution should be exercised when extrapolating these results to the clinic. PMID:25697050

  16. Slab stagnation and detachment under northeast China

    NASA Astrophysics Data System (ADS)

    Honda, Satoru

    2016-03-01

    Results of tomography models around the Japanese Islands show the existence of a gap between the horizontally lying (stagnant) slab extending under northeastern China and the fast seismic velocity anomaly in the lower mantle. A simple conversion from the fast velocity anomaly to the low-temperature anomaly shows a similar feature. This feature appears to be inconsistent with the results of numerical simulations on the interaction between the slab and phase transitions with temperature-dependent viscosity. Such numerical models predict a continuous slab throughout the mantle. I extend previous analyses of the tomography model and model calculations to infer the origins of the gap beneath northeastern China. Results of numerical simulations that take the geologic history of the subduction zone into account suggest two possible origins for the gap: (1) the opening of the Japan Sea led to a breaking off of the otherwise continuous subducting slab, or (2) the western edge of the stagnant slab is the previous subducted ridge, which was the plate boundary between the extinct Izanagi and the Pacific plates. Origin (2) suggesting the present horizontally lying slab has accumulated since the ridge subduction, is preferable for explaining the present length of the horizontally lying slab in the upper mantle. Numerical models of origin (1) predict a stagnant slab in the upper mantle that is too short, and a narrow or non-existent gap. Preferred models require rather stronger flow resistance of the 660-km phase change than expected from current estimates of the phase transition property. Future detailed estimates of the amount of the subducted Izanagi plate and the present stagnant slab would be useful to constrain models. A systematic along-arc variation of the slab morphology from the northeast Japan to Kurile arcs is also recognized, and its understanding may constrain the 3D mantle flow there.

  17. Turbulence in the cylindrical slab

    SciTech Connect

    Gentle, K. W.; Rowan, W. L.; Williams, C. B.; Brookman, M. W.

    2014-09-15

    The cylindrical slab was the first and simplest model of intrinsically unstable microturbulence. The Helimak is an experimental realization of this model. Although finite, it is sufficiently large to escape boundary effects, with dimensionless parameters similar to those of a tokamak edge or scrape off layer. The essential drive is interchange-like, a pressure gradient with unfavorable magnetic curvature, leading to a non-linearly saturated state of large-amplitude turbulence, Δn{sub rms}/n ∼ 0.5. The nonlinear processes governing this saturation are unique, unlike any of those posited for the much weaker turbulence typical of confined plasma, e.g., in a tokamak. Neither linear stability theory, quasi-linear theory, zonal flows, nor flow shear stabilization is consistent with the observations. The mechanisms determining the non-linearly saturated state constitute an important challenge to our understanding of strongly nonlinear systems.

  18. Magnetoelectric sensor excitations in hexaferrite slabs

    NASA Astrophysics Data System (ADS)

    Zare, Saba; Izadkhah, Hessam; Somu, Sivasubramanian; Vittoria, Carmine

    2015-06-01

    We developed techniques for H- and E-field sensors utilizing single phase magnetoelectric (ME) hexaferrite slabs in the frequency range of 100 Hz to 10 MHz. Novel circuit designs incorporating both spiral and solenoid coils and single and multi-capacitor banks were developed to probe the physics and properties of ME hexaferrites and explore ME effects for sensor detections. Fundamental measurements of the anisotropic tensor elements of the magneto-electric coupling parameter were performed using these novel techniques. In addition, for H-field sensing experiments we measured sensitivity of about 3000 Vm-1/G using solenoid coils and 8000 Vm-1/G using spiral coils. For E-field, sensing the sensitivity was 10-4 G/Vm-1 and using single capacitor detector. Sensitivity for multi-capacitor detectors was measured to be in the order of 10-3 G/Vm-1 and frequency dependent exhibiting a maximum value at ˜1 MHz. Tunability of 0.1%-90% was achieved for tunable inductor applications using both single and multi-capacitors excitation. We believe that significant (˜106) improvements in sensitivity and tunability are feasible with simple modifications of the fabrication process.

  19. A high speed profiler based slab curvature index for jointed concrete pavement curling and warping analysis

    NASA Astrophysics Data System (ADS)

    Byrum, Christopher Ronald

    One of the biggest gaps of missing knowledge between accurate structural modeling of concrete pavement slab behavior and real pavement behavior is accounting for slab warping (locked-in curvature and moisture gradient effects) and curling (temperature gradient effects). Curling and warping are curvatures that can be present in a PCC slab that can cause corners and edges, or mid panel, of the slab to lift off of the ground resulting in relatively high deflection and stress in the system. The least understood type of curvature in slabs is apparent locked-in curvature, which can become excessive and control the overall behavior of the pavement system. This project is focused on quantifying slab curvatures and the effects of apparent locked-in curvature on the behavior and long-term performance of pavement systems. A high-speed profile analysis technique for detecting the amount of slab curvatures along pavement wheel paths is described. This signal processing technique can detect relatively small curvature variations in high-speed pavement elevation profiles obtained at normal highway operating speeds using special vehicles. A resulting curvature detection algorithm is applied to the Federal Highway Administration (FHWA) Long Term Pavement Performance (LTPP) database high-speed pavement profiles for jointed concrete pavements. The range and nature of slab curvatures detected in the profiles is described. The calculated locked-in curvature at the various pavement sites is compared to LTPP database information to evaluate curvature effects on pavement deterioration rates and the relation between site parameters and locked-in curvature. The significance of slab curvature is shown through statistics and predictive models developed for various pavement distress modes. It is shown that the amount of curvature locked into concrete slabs is one of the strongest factors in the FHWA LTPP data correlated to deterioration of pavements. This study shows that preventing locked

  20. Seismic monitoring of hydraulic fracturing: techniques for determining fluid flow paths and state of stress away from a wellbore

    SciTech Connect

    Fehler, M.; House, L.; Kaieda, H.

    1986-01-01

    Hydraulic fracturing has gained in popularity in recent years as a way to determine the orientations and magnitudes of tectonic stresses. By augmenting conventional hydraulic fracturing measurements with detection and mapping of the microearthquakes induced by fracturing, we can supplement and idependently confirm information obtained from conventional analysis. Important information obtained from seismic monitoring includes: the state of stress of the rock, orientation and spacing of the major joint sets, and measurements of rock elastic parameters at locations distant from the wellbore. While conventional well logging operations can provide information about several of these parameters, the zone of interrogation is usually limited to the immediate proximity of the borehole. The seismic waveforms of the microearthquakes contain a wealth of information about the rock in regions that are otherwise inaccessible for study. By reliably locating the hypocenters of many microearthquakes, we have inferred the joint patterns in the rock. We observed that microearthquake locations do not define a simple, thin, planar distribution, that the fault plane solutions are consistent with shear slippage, and that spectral analysis indicates that the source dimensions and slip along the faults are small. Hence we believe that the microearthquakes result from slip along preexisting joints, and not from tensile extension at the tip of the fracture. Orientations of the principal stresses can be estimated by using fault plane solutions of the larger microearthquakes. By using a joint earthquake location scheme, and/or calibrations with downhole detonators, rock velocities and heterogeneities thereof can be investigated in rock volumes that are far enough from the borehole to be representative of intrincis rock properties.

  1. Comparison of Surgical Outcomes Between Short-Segment Open and Percutaneous Pedicle Screw Fixation Techniques for Thoracolumbar Fractures.

    PubMed

    Fu, Zhiguo; Zhang, Xi; Shi, Yaohua; Dong, Qirong

    2016-01-01

    BACKGROUND This study aimed to compare the surgical outcomes between open pedicle screw fixation (OPSF) and percutaneous pedicle screw fixation (PPSF) for the treatment of thoracolumbar fractures, which has received scant research attention to date. MATERIAL AND METHODS Eight-four patients with acute and subacute thoracolumbar fractures who were treated with SSPSF from January 2013 to June 2014 at the Changzhou Hospital of Traditional Chinese Medicine (Changzhou, China) were retrospectively reviewed. The patients were divided into 4 groups: the OPSF with 4 basic screws (OPSF-4) group, the OPSF with 4 basic and 2 additional screws (OPSF-6) group, the PPSF with 4 basic screws (PPSF-4) group, and the PPSF with 4 basic and 2 additional screws (PPSF-6) group. The intraoperative, immediate postoperative, and over 1-year follow-up outcomes were evaluated and compared among these groups. RESULTS Blood loss in the PPSF-4 group and the PPSF-6 group was significantly less than in the OPSF-4 group and the OPSF-6 group (P<0.05). The OPSF-6 group exhibited significantly higher immediate postoperative correction percentage of anterior column height of fractured vertebra than the other 3 groups (P<0.05), and higher correction of sagittal regional Cobb angle and kyphotic angle of injured vertebra than in the PPSF-4 and -6 groups (P<0.05). In addition, there was no significant difference in the correction loss of percentage of anterior column height, and loss of sagittal Cobb angle and kyphotic angle of fractured vertebrae at final follow-up among the 4 groups (P>0.05). CONCLUSIONS OPSF with 6 screws had an advantage in the correction of injured vertebral height and kyphosis, and PPSF reduced the intraoperative blood loss of patients. PMID:27602557

  2. Comparison of Surgical Outcomes Between Short-Segment Open and Percutaneous Pedicle Screw Fixation Techniques for Thoracolumbar Fractures

    PubMed Central

    Fu, Zhiguo; Zhang, Xi; Shi, Yaohua; Dong, Qirong

    2016-01-01

    Background This study aimed to compare the surgical outcomes between open pedicle screw fixation (OPSF) and percutaneous pedicle screw fixation (PPSF) for the treatment of thoracolumbar fractures, which has received scant research attention to date. Material/Methods Eight-four patients with acute and subacute thoracolumbar fractures who were treated with SSPSF from January 2013 to June 2014 at the Changzhou Hospital of Traditional Chinese Medicine (Changzhou, China) were retrospectively reviewed. The patients were divided into 4 groups: the OPSF with 4 basic screws (OPSF-4) group, the OPSF with 4 basic and 2 additional screws (OPSF-6) group, the PPSF with 4 basic screws (PPSF-4) group, and the PPSF with 4 basic and 2 additional screws (PPSF-6) group. The intraoperative, immediate postoperative, and over 1-year follow-up outcomes were evaluated and compared among these groups. Results Blood loss in the PPSF-4 group and the PPSF-6 group was significantly less than in the OPSF-4 group and the OPSF-6 group (P<0.05). The OPSF-6 group exhibited significantly higher immediate postoperative correction percentage of anterior column height of fractured vertebra than the other 3 groups (P<0.05), and higher correction of sagittal regional Cobb angle and kyphotic angle of injured vertebra than in the PPSF-4 and -6 groups (P<0.05). In addition, there was no significant difference in the correction loss of percentage of anterior column height, and loss of sagittal Cobb angle and kyphotic angle of fractured vertebrae at final follow-up among the 4 groups (P>0.05). Conclusions OPSF with 6 screws had an advantage in the correction of injured vertebral height and kyphosis, and PPSF reduced the intraoperative blood loss of patients. PMID:27602557

  3. Strength analysis of clavicle fracture fixation devices and fixation techniques using finite element analysis with musculoskeletal force input.

    PubMed

    Marie, Cronskär

    2015-08-01

    In the cases, when clavicle fractures are treated with a fixation plate, opinions are divided about the best position of the plate, type of plate and type of screw units. Results from biomechanical studies of clavicle fixation devices are contradictory, probably partly because of simplified and varying load cases used in different studies. The anatomy of the shoulder region is complex, which makes it difficult and expensive to perform realistic experimental tests; hence, reliable simulation is an important complement to experimental tests. In this study, a method for finite element simulations of stresses in the clavicle plate and bone is used, in which muscle and ligament force data are imported from a multibody musculoskeletal model. The stress distribution in two different commercial plates, superior and anterior plating position and fixation including using a lag screw in the fracture gap or not, was compared. Looking at the clavicle fixation from a mechanical point of view, the results indicate that it is a major benefit to use a lag screw to fixate the fracture. The anterior plating position resulted in lower stresses in the plate, and the anatomically shaped plate is more stress resistant and stable than a regular reconstruction plate.

  4. Effect of novel restoration techniques on the fracture resistance of teeth treated endodontically: An in vitro study.

    PubMed

    Kemaloglu, Hande; Emin Kaval, Mehmet; Turkun, Murat; Micoogullari Kurt, Seniha

    2015-01-01

    The aim was to evaluate the effects of fiber-reinforced composite restorations and a bulk-fill resin composite on the fracture strength of mandibular premolars treated endodontically. Standard mesio-occluso-distal (MOD) cavities were prepared in 48 mandibular premolars. Following root canal treatment, teeth were assigned to four groups: Group 1, nano-hybrid resin composite; Group 2, polyethylene woven fiber plus nano-hybrid resin composite; Group 3, short fiber-reinforced resin composite plus nano-hybrid resin composite; and Group 4, bulk-fill resin composite plus nano-hybrid resin composite. Then, the teeth were subjected to the fracture toughness test. The data were analyzed statistically using one-way ANOVA, followed by Tukey's post-hoc test. The fiber-reinforced groups had better results than the nano-hybrid and bulk-fill composites (p<0.05), while the bulk-fill and nano-hybrid composite restorations gave similar results (p>0.05). Fiber-reinforcement improved the fracture strength of teeth with large MOD cavities treated endodontically. Bulk-fill composites can be used reliably as well as nano-hybrid composites.

  5. Scattering by dielectric circular cylinders in a dielectric slab.

    PubMed

    Frezza, Fabrizio; Pajewski, Lara; Ponti, Cristina; Schettini, Giuseppe

    2010-04-01

    An analytical-numerical technique for the solution of the plane-wave scattering problem by a set of dielectric cylinders embedded in a dielectric slab is presented. Scattered fields are expressed by means of expansions into cylindrical functions, and the concept of plane-wave spectrum of a cylindrical function is employed to define reflection and transmission through the planar interfaces. Multiple reflection phenomena due to the presence of a layered geometry are taken into account. Solutions can be obtained for both TM and TE polarizations and for near- and far-field regions. The numerical approach is described and the method is validated by comparison with examples given in the literature, with very good agreement. Results are presented for the scattering by a finite grid of three cylinders embedded in a slab.

  6. Sausage oscillations of coronal plasma slabs

    NASA Astrophysics Data System (ADS)

    Hornsey, C.; Nakariakov, V. M.; Fludra, A.

    2014-07-01

    Context. Sausage oscillations are observed in plasma non-uniformities of the solar corona as axisymmetric perturbations of the non-uniformity. Often, these non-uniformities can be modelled as field-aligned slabs of the density enhancement. Aims: We perform parametric studies of sausage oscillations of plasma slabs, aiming to determine the dependence of the oscillation period on its parameters, and the onset of leaky and trapped regimes of the oscillations. Methods: Slabs with smooth transverse profiles of the density of a zero-beta plasma are perturbed by an impulsive localised perturbation of the sausage symmetry. In particular, the slab can contain an infinitely thin current sheet in its centre. The initial value problem is then solved numerically. The numerical results are subject to spectral analysis. The results are compared with analytical solutions for a slab with a step-function profile and also with sausage oscillations of a plasma cylinder. Results: We established that sausage oscillations in slabs generally have the same properties as in plasma cylinders. In the trapped regime, the sausage oscillation period increases with the increase in the longitudinal wavelength. In the leaky regime, the dependence of the period on the wavelength experiences saturation, and the period becomes independent of the wavelength in the long-wavelength limit. In the leaky regime the period is always longer than in the trapped regime. The sausage oscillation period in a slab is always longer than in a cylinder with the same transverse profile. In slabs with steeper transverse profiles, sausage oscillations have longer periods. The leaky regime occurs at shorter wavelengths in slabs with smoother profiles.

  7. Constraints of subducted slab geometries on trench migration and subduction velocities: flat slabs and slab curtains in the mantle under Asia

    NASA Astrophysics Data System (ADS)

    Wu, J. E.; Suppe, J.; Renqi, L.; Lin, C.; Kanda, R. V.

    2013-12-01

    The past locations, shapes and polarity of subduction trenches provide first-order constraints for plate tectonic reconstructions. Analogue and numerical models of subduction zones suggest that relative subducting (Vs) and overriding (Vor) plate velocities may strongly influence final subducted slab geometries. Here we have mapped the 3D geometries of subducted slabs in the upper and lower mantle of Asia from global seismic tomography. We have incorporated these slabs into plate tectonic models, which allows us to infer the subducting and overriding plate velocities. We describe two distinct slab geometry styles, ';flat slabs' and ';slab curtains', and show their implications for paleo-trench positions and subduction geometries in plate tectonic reconstructions. When compared to analogue and numerical models, the mapped slab styles show similarities to modeled slabs that occupy very different locations within Vs:Vor parameter space. ';Flat slabs' include large swaths of sub-horizontal slabs in the lower mantle that underlie the well-known northward paths of India and Australia from Eastern Gondwana, viewed in a moving hotspot reference. At India the flat slabs account for a significant proportion of the predicted lost Ceno-Tethys Ocean since ~100 Ma, whereas at Australia they record the existence of a major 8000km by 2500-3000km ocean that existed at ~43 Ma between East Asia, the Pacific and Australia. Plate reconstructions incorporating the slab constraints imply these flat slab geometries were generated when continent overran oceanic lithosphere to produce rapid trench retreat, or in other words, when subducting and overriding velocities were equal (i.e. Vs ~ Vor). ';Slab curtains' include subvertical Pacific slabs near the Izu-Bonin and Marianas trenches that extend from the surface down to 1500 km in the lower mantle and are 400 to 500 km thick. Reconstructed slab lengths were assessed from tomographic volumes calculated at serial cross-sections. The ';slab

  8. Epithelialization Over a Scaffold of Antibiotic-Impregnated PMMA Beads: A Salvage Technique for Open Tibial Fractures with Bone and Soft Tissue Loss When all Else Fails.

    PubMed

    Masrouha, Karim Z; El-Bitar, Youssef; Najjar, Marc; Saghieh, Said

    2016-06-01

    The management of soft tissue defects in tibial fractures is essential for limb preservation. Current techniques are not without complications and may lead to poor functional outcomes. A salvage method is described using three illustrative cases whereby a combination of flaps and antibiotic-impregnated polymethylmethacrylate beads are employed to fill the bony defect, fight the infection, and provide a surface for epithelial regeneration and secondary wound closure. This was performed after the partial failure of all other options. All patients were fully ambulatory with no clinical, radiographic or laboratory sign of infection at their most recent follow-up. Although our findings are encouraging, this is the first report of epithelialization of the skin on a polymethylmethacrylate scaffold. Further studies investigating the use of this technique are warranted. PMID:27517073

  9. Epithelialization Over a Scaffold of Antibiotic-Impregnated PMMA Beads: A Salvage Technique for Open Tibial Fractures with Bone and Soft Tissue Loss When all Else Fails

    PubMed Central

    Masrouha, Karim Z.; El-Bitar, Youssef; Najjar, Marc; Saghieh, Said

    2016-01-01

    The management of soft tissue defects in tibial fractures is essential for limb preservation. Current techniques are not without complications and may lead to poor functional outcomes. A salvage method is described using three illustrative cases whereby a combination of flaps and antibiotic-impregnated polymethylmethacrylate beads are employed to fill the bony defect, fight the infection, and provide a surface for epithelial regeneration and secondary wound closure. This was performed after the partial failure of all other options. All patients were fully ambulatory with no clinical, radiographic or laboratory sign of infection at their most recent follow-up. Although our findings are encouraging, this is the first report of epithelialization of the skin on a polymethylmethacrylate scaffold. Further studies investigating the use of this technique are warranted. PMID:27517073

  10. Sensitivity enhancement in photonic crystal slab biosensors.

    PubMed

    El Beheiry, Mohamed; Liu, Victor; Fan, Shanhui; Levi, Ofer

    2010-10-25

    Refractive index sensitivity of guided resonances in photonic crystal slabs is analyzed. We show that modal properties of guided resonances strongly affect spectral sensitivity and quality factors, resulting in substantial enhancement of refractive index sensitivity. A three-fold spectral sensitivity enhancement is demonstrated for suspended slab designs, in contrast to designs with a slab resting over a substrate. Spectral sensitivity values are additionally shown to be unaffected by quality factor reductions, which are common to fabricated photonic crystal nano-structures. Finally, we determine that proper selection of photonic crystal slab design parameters permits biosensing of a wide range of analytes, including proteins, antigens, and cells. These photonic crystals are compatible with large-area biosensor designs, permitting direct access to externally incident optical beams in a microfluidic device.

  11. TESTING OF INDOOR RADON REDUCTION TECHNIQUES IN CENTRAL OHIO HOUSES: PHASE 2 (WINTER 1988-1989)

    EPA Science Inventory

    The report gives results of tests of developmental indoor radon reduction techniques in nine slab-on-grade and four crawl-space houses near Dayton. Ohio. he slab-on-grade tests indicated that, when there is a good layer of aggregate under the slab, the sub-slab ventilation (SSV) ...

  12. Crust rheology, slab detachment and topography

    NASA Astrophysics Data System (ADS)

    Duretz, T.; Gerya, T. V.

    2012-04-01

    The collision between continents following the closure of an ocean can lead to the subduction of continental crust. The introduction of buoyant crust within subduction zones triggers the development of extensional stresses in slabs which eventually result in their detachment. The dynamic consequences of slab detachment affects the development of topography, the exhumation of high-pressure rocks and the geodynamic evolution of collision zones. We employ two-dimensional thermo-mechanical modelling in order to study the importance of crustal rheology on the evolution of spontaneous subduction-collision systems and the occurrence of slab detachment. The modelling results indicate that varying the rheological structure of the crust can results in a broad range of collisional evolutions involving slab detachment, delamination (associated to slab rollback), or the combination of both mechanisms. By enhancing mechanical coupling at the Moho, a strong crust leads to the deep subduction of the crust (180 km). These collisions are subjected to slab detachment and subsequent coherent exhumation of the crust accommodated by eduction (inversion of subduction sense) and thrusting. In these conditions, slab detachment promotes the development of a high (> 4.5 km) and narrow (< 200 km) topographic plateau located in the vicinity of the suture. A contrasting style of collision is obtained by employing a weak crustal rheology. The weak mechanical coupling at the Moho promotes the widespread delamination of the lithosphere, preventing slab detachment to occur. Further shortening leads to buckling and thickening of the crust resulting in the development of topographic bulging on the lower plate. Collisions involving rheologically layered crust are characterised by a decoupling level at mid-crustal depths. These initial condition favours the delamination of the upper crust as well as the deep subduction of the lower crust. These collisions are thus successively affected by delamination

  13. Photocatalytic, highly hydrophilic porcelain stoneware slabs

    NASA Astrophysics Data System (ADS)

    Raimondo, M.; Guarini, G.; Zanelli, C.; Marani, F.; Fossa, L.; Dondi, M.

    2011-10-01

    Photocatalytic, highly hydrophilic industrial porcelain stoneware large slabs were realized by deposition of nanostructured TiO2 coatings. Different surface finishing and experimental conditions were considered in order to assess the industrial feasibility. Photocatalytic and wetting behaviour of functionalized slabs mainly depends on surface phase composition in terms of anatase/rutile ratio, this involving - as a key issue - the deposition of TiO2 on industrially sintered products with an additional annealing step to strengthen coatings' performances and durability.

  14. The load separation technique in the elastic-plastic fracture analysis of two- and three-dimensional geometries

    NASA Technical Reports Server (NTRS)

    Sharobeam, Monir H.

    1994-01-01

    Load separation is the representation of the load in the test records of geometries containing cracks as a multiplication of two separate functions: a crack geometry function and a material deformation function. Load separation is demonstrated in the test records of several two-dimensional geometries such as compact tension geometry, single edge notched bend geometry, and center cracked tension geometry and three-dimensional geometries such as semi-elliptical surface crack. The role of load separation in the evaluation of the fracture parameter J-integral and the associated factor eta for two-dimensional geometries is discussed. The paper also discusses the theoretical basis and the procedure for using load separation as a simplified yet accurate approach for plastic J evaluation in semi-elliptical surface crack which is a three-dimensional geometry. The experimental evaluation of J, and particularly J(sub pl), for three-dimensional geometries is very challenging. A few approaches have been developed in this regard and they are either complex or very approximate. The paper also presents the load separation as a mean to identify the blunting and crack growth regions in the experimental test records of precracked specimens. Finally, load separation as a methodology in elastic-plastic fracture mechanics is presented.

  15. Application Improvements of Slab-Coupled Optical Fiber Sensors

    NASA Astrophysics Data System (ADS)

    Chadderdon, Spencer Lee

    This dissertation explores techniques for improving slab-coupled optical fiber sensor (SCOS) technology for use in specific applications and sensing configurations. SCOS are advantageous for their small size and all-dielectric composition which permit non-intrusive measurement of electric fields within compact environments; however, their small size also limits their sensitivity. This work performs a thorough analysis of the factors contributing to the performance of SCOS and demonstrates methods which improve SCOS, while maintaining its small dimensions and high level of directional sensitivity. These improvements include increasing the sensitivity by 9x, improving the frequency response to include sub 300 kHz frequencies, and developing a method to tune the resonances. The analysis shows that the best material for the slab waveguide is an electro-optic polymer because of its low RF permittivity combined with high electro-optic coefficient. Additional improvements are based on changing the crystal orientation to a transverse configuration, which enhances the sensitivity due to a combined increase in the effective electro-optic coefficient and electric field penetration into the slab. The transverse SCOS configuration not only improves the overall sensitivity but increases the directional sensitivity of the SCOS. Lithium niobate and electro-optic polymer are both experimentally shown to exhibit minimal frequency dependent sensitivity making them suitable for broad frequency applications. Simultaneous interrogation of multiple SCOS with a single tunable laser is achieved by tuning the resonant wavelengths of KTP SCOS so their resonances overlap.

  16. Repetitively pulsed Nd-glass slab lasers

    NASA Astrophysics Data System (ADS)

    Denker, B. I.; Kir'ianov, A. V.; Maliutin, A. A.; Kertesz, I.; Kroo, N.

    1989-09-01

    The possibility of obtaining high laser output energies at 1.32 micron using thin LiNdLa phosphate glass slabs with a high Nd(3+) concentration is discussed. Comparison data for 1.054 micron are also given. In the experiments, 3 x 14 x 125-mm slabs were prepared from LiNdLa phosphate glass with Nd concentration 1.2 x 10 to the 21st/cu cm. The uncoated slab facets were tested in a silver-coated quartz tube reflector pumped by 450-microsec flash-lamp pulses. The light passing through the slab returns to it after reflection from the tube surface. Most of the radiation falls on the wider side of the slab at large angles of incidence, thus maximizing its path inside the slab. The 150-mm laser resonator was formed by two flat mirrors. At 1.32 microns an output mirror of reflectivity r = 95 percent was used (with r less than 10 percent at 1.054 micron), while at 1.054 micron, r(output) = 50 percent was chosen. The pump-energy dependence of the output energy was measured.

  17. Three-dimensional necking during viscous slab detachment

    NASA Astrophysics Data System (ADS)

    Tscharner, M.; Schmalholz, S. M.; Duretz, T.

    2014-06-01

    We study the three-dimensional (3-D) deformation during detachment of a lithospheric slab with simple numerical models using the finite element method. An initially vertical layer of power law viscous fluid mimics the slab and is surrounded by a linear or power law viscous fluid representing asthenospheric mantle. We quantify the impact of slab size and shape (symmetric/asymmetric) on slab detachment and identify two processes that control the lateral (i.e., along-trench) slab deformation: (1) the horizontal deflection of the lateral, vertical slab sides (> 100 km with velocities up to 16 mm/yr) and (2) the propagation of localized thinning (necking) inside the slab (with velocities >9 cm/yr). The lateral propagation velocity is approximately constant during slab detachment. Larger slabs (here wider than approximately 300 km) detach with rates similar to those predicted by 2-D models, whereas smaller slabs detach slower. Implications for geodynamic processes and interpretations of seismic tomography are discussed.

  18. Tomographically-imaged subducted slabs and magmatic history of Caribbean and Pacific subduction beneath Colombia

    NASA Astrophysics Data System (ADS)

    Bernal-Olaya, R.; Mann, P.; Vargas, C. A.; Koulakov, I.

    2013-12-01

    We define the length and geometry of eastward and southeastward-subducting slabs beneath northwestern South America in Colombia using ~100,000 earthquake events recorded by the Colombian National Seismic Network from 1993 to 2012. Methods include: hypocenter relocation, compilation of focal mechanisms, and P and S wave tomographic calculations performed using LOTOS and Seisan. The margins of Colombia include four distinct subduction zones based on slab dip: 1) in northern Colombia, 12-16-km-thick oceanic crust subducts at a modern GPS rate of 20 mm/yr in a direction of 110 degrees at a shallow angle of 8 degrees; as a result of its low dip, Pliocene-Pleistocene volcanic rocks are present 400 km from the frontal thrust; magmatic arc migration to the east records 800 km of subduction since 58 Ma ago (Paleocene) with shallow subduction of the Caribbean oceanic plateau starting ~24-33 Ma (Miocene); at depths of 90-150 km, the slab exhibits a negative velocity anomaly we associate with pervasive fracturing; 2) in the central Colombia-Panama area, we define an area of 30-km-thick crust of the Panama arc colliding/subducting at a modern 30/mm in a direction of 95 degrees; the length of this slab shows subduction/collision initiated after 20 Ma (Middle Miocene); we call this feature the Panama indenter since it has produced a V-shaped indentation of the Colombian margin and responsible for widespread crustal deformation and topographic uplift in Colombia; an incipient subduction area is forming near the Panama border with intermediate earthquakes at an eastward dip of 70 degrees to depths of ~150 km; this zone is not visible on tomographic images; 3) a 250-km-wide zone of Miocene oceanic crust of the Nazca plate flanking the Panama indenter subducts at a rate of 25 mm/yr in a direction of 55 degrees and at a normal dip of 40 degrees; the length of this slab suggests subduction began at ~5 Ma; 4) the Caldas tear defines a major dip change to the south where a 35 degrees

  19. Was there a Laramide "flat slab"?

    NASA Astrophysics Data System (ADS)

    Jones, C. H.

    2014-12-01

    Slab-continent interactions drive most non-collisional orogenies; this has led us to usually anticipate that temporal changes or spatial variations in orogenic style are related to changes in the slab, most especially in the slab's dip. This is most dramatically evident for orogenies in the foreland, well away from the trench, such as the Laramide orogeny. However, the physical means of connecting slab geometry to crustal deformation remain obscure. Dickinson and Snyder (1978) and Bird (1984) laid out a conceptually elegant means of creating foreland deformation from shear between a slab and overriding continental lithosphere, but such strong shear removed all of the continental lithosphere in the western U.S. when included in a numerical simulation of flat slab subduction (Bird, 1988), a removal in conflict with observations of volcanic rocks and xenoliths in many locations. Relying on an increase in edge normal stresses results, for the Laramide, in requiring the little-deformed Colorado Plateau to either be unusually strong or to have risen rapidly enough and high enough to balance edge stresses with body forces. Early deformation in the Plateau rules out unusual strength, and the accumulation and preservation of Late Cretaceous near-sea level sedimentary rocks makes profound uplift unlikely (though not impossible). Relying on comparisons with the Sierras Pampeanas is also fraught with problems: the Sierras are not separated from the Andean fold-and-thrust belt by several hundred kilometers of little-deformed crust, nor were they buried under kilometers of marine muds as were large parts of the Laramide foreland. We have instead suggested that some unusual interactions of an obliquely subducting plate with a thick Archean continental root might provide a better explanation than a truly flat slab (Jones et al., 2011). From this, and given that several flat-slab segments today are not associated with foreland orogenesis and noting that direct evidence for truly

  20. Mantle subducting slab structure in the region of the 2010 M8.8 Maule earthquake (30-40°S), Chile

    NASA Astrophysics Data System (ADS)

    Pesicek, J. D.; Engdahl, E. R.; Thurber, C. H.; DeShon, H. R.; Lange, D.

    2012-10-01

    We present a new tomographic model of the mantle in the area of the 2010 M8.8 Maule earthquake and surrounding regions. Increased ray coverage provided by the aftershock data allows us to image the detailed subducting slab structure in the mantle, from the region of flat slab subduction north of the Maule rupture to the area of overlapping rupture between the 1960 M9.5 and the 2010 M8.8 events to the south. We have combined teleseismic primary and depth phase arrivals with available local arrivals to better constrain the teleseismic earthquake locations in the region, which we use to conduct nested regional-global tomography. The new model reveals the detailed structure of the flat slab and its transition to a more moderately dipping slab in the Maule region. South of the Maule region, a steeply dipping relic slab is imaged from ˜200 to 1000 km depth that is distinct from the moderately dipping slab above it and from the more northerly slab at similar depths. We interpret the images as revealing both horizontal and vertical tearing of the slab at ˜38°S to explain the imaged pattern of slab anomalies in the southern portion of the model. In contrast, the transition from a horizontal to moderately subducting slab in the northern portion of the model is imaged as a continuous slab bend. We speculate that the tearing was most likely facilitated by a fracture zone in the downgoing plate or alternatively by a continental scale terrane boundary in the overriding plate.

  1. Cracking behavior of structural slab bridge decks

    NASA Astrophysics Data System (ADS)

    Baah, Prince

    Bridge deck cracking is a common problem throughout the United States, and it affects the durability and service life of concrete bridges. Several departments of transportation (DOTs) in the United States prefer using continuous three-span solid structural slab bridges without stringers over typical four-lane highways. Recent inspections of such bridges in Ohio revealed cracks as wide as 0.125 in. These measured crack widths are more than ten times the maximum limit recommended in ACI 224R-01 for bridge decks exposed to de-icing salts. Measurements using digital image correlation revealed that the cracks widened under truck loading, and in some cases, the cracks did not fully close after unloading. This dissertation includes details of an experimental investigation of the cracking behavior of structural concrete. Prism tests revealed that the concrete with epoxy-coated bars (ECB) develops the first crack at smaller loads, and develops larger crack widths compared to the corresponding specimens with uncoated (black) bars. Slab tests revealed that the slabs with longitudinal ECB developed first crack at smaller loads, exhibited wider cracks and a larger number of cracks, and failed at smaller ultimate loads compared to the corresponding test slabs with black bars. To develop a preventive measure, slabs with basalt and polypropylene fiber reinforced concrete were also included in the test program. These test slabs exhibited higher cracking loads, smaller crack widths, and higher ultimate loads at failure compared to the corresponding slab specimens without fibers. Merely satisfying the reinforcement spacing requirements given in AASHTO or ACI 318-11 is not adequate to limit cracking below the ACI 224R-01 recommended maximum limit, even though all the relevant design requirements are otherwise met. Addition of fiber to concrete without changing any steel reinforcing details is expected to reduce the severity and extent of cracking in reinforced concrete bridge decks.

  2. History vs. snapshot: how slab morphology relates to slab age evolution

    NASA Astrophysics Data System (ADS)

    Garel, Fanny; Goes, Saskia; Davies, Rhodri; Davies, Huw; Lallemand, Serge; Kramer, Stephan; Wilson, Cian

    2016-04-01

    The age of the subducting plate at the trench ("slab age") spans a wide range, from less than 10 Myr in Central and South America to 150 Myr in the Marianas. The morphology of subducting slab in the upper mantle is also very variable, from slabs stagnating at the top of the lower mantle to slabs penetrating well beyond 1000 km depth. People have looked rather unsucessfully for correlations between slab morphology and subduction parameters, including age at the trench, on the basic assumption that old (thick) plates are likely to generate a large slab pull force that would influence slab dip. Thermo-mechanical models reveal complex feedbacks between temperature, strain rate and rheology, and are able to reproduce the evolution of plate ages as a function of time, subducting plate velocity and trench velocity. In particular, we show how initially young subducting plates can rapidly age at the surface because of a slow sinking velocity. As a consequence, different slab morphologies can exhibit similar ages at the trench provided that subduction history is different. We illustrate how models provide insights into Earth subduction zones for which we have to consider their history (evolution of trench velocity, relative plate ages at time of initiation) in order to unravel their present-day geometry.

  3. Osteoporotic Hip and Spine Fractures

    PubMed Central

    Hill, Brian W.

    2014-01-01

    Hip and spine fractures represent just a portion of the burden of osteoporosis; however, these fractures require treatment and often represent a major change in lifestyle for the patient and their family. The orthopedic surgeon plays a crucial role, not only in the treatment of these injuries but also providing guidance in prevention of future osteoporotic fractures. This review provides a brief epidemiology of the fractures, details the surgical techniques, and outlines the current treatment guidelines for orthopedic surgeons. PMID:26246944

  4. Experimental Study of Slabbing and Rockburst Induced by True-Triaxial Unloading and Local Dynamic Disturbance

    NASA Astrophysics Data System (ADS)

    Du, Kun; Tao, Ming; Li, Xi-bing; Zhou, Jian

    2016-09-01

    Slabbing/spalling and rockburst are unconventional types of failure of hard rocks under conditions of unloading and various dynamic loads in environments with high and complex initial stresses. In this study, the failure behaviors of different rock types (granite, red sandstone, and cement mortar) were investigated using a novel testing system coupled to true-triaxial static loads and local dynamic disturbances. An acoustic emission system and a high-speed camera were used to record the real-time fracturing processes. The true-triaxial unloading test results indicate that slabbing occurred in the granite and sandstone, whereas the cement mortar underwent shear failure. Under local dynamically disturbed loading, none of the specimens displayed obvious fracturing at low-amplitude local dynamic loading; however, the degree of rock failure increased as the local dynamic loading amplitude increased. The cement mortar displayed no failure during testing, showing a considerable load-carrying capacity after testing. The sandstone underwent a relatively stable fracturing process, whereas violent rockbursts occurred in the granite specimen. The fracturing process does not appear to depend on the direction of local dynamic loading, and the acoustic emission count rate during rock fragmentation shows that similar crack evolution occurred under the two test scenarios (true-triaxial unloading and local dynamically disturbed loading).

  5. Sensors and Monitoring Techniques for the Deep Unsaturated Zone: Reducing Uncertainty Related to Seepage and Transport in Fractured Rock

    NASA Astrophysics Data System (ADS)

    Dinwiddie, C. L.; Or, D.; Stothoff, S. A.; Fedors, R. W.; Pohle, J. A.; Tuller, M.

    2007-12-01

    Planning for performance confirmation of hydrologic properties and processes in a potential geologic repository for high-level radioactive waste at Yucca Mountain is a requirement stated in Subpart F of 10 CFR Part 63. An important goal of performance confirmation is to acquire information indicating whether natural and engineered barriers are functioning as intended, and whether the conditions encountered are within the limits assumed during a licensing review. Long-term monitoring of hydrologic properties and processes and in situ confirmation of design assumptions will play a key role in the safe operation of the potential geologic radioactive waste repository and in the decision to close the repository. Despite remarkable advances in cyberinfrastructure for linking sensors into spatially distributed environmental networks, the extended time horizon (decades to hundreds of years) for long-term monitoring activities, the harsh thermal and radiative conditions in the near-field environment, the deep fractured unsaturated rock environment at Yucca Mountain, the potential scope of observations, and restricted access to observation ports for maintenance and upgrades each present unprecedented challenges to the design of hydro-environmental monitoring networks. Activities for performance confirmation could include the use of pore water samplers and sensors for measuring water content, matric potential, temperature, relative humidity, and water and gas fluxes. Current sensor technology for deep fractured rock systems (i) lags behind environmental observatory network solutions for surface and near-surface processes, (ii) lags behind analogous technology for unconsolidated porous media, (iii) cannot be reliably deployed without ongoing maintenance or replacement at relatively frequent intervals, and (iv) is not designed to withstand harsh thermal and radiative conditions. Long-term monitoring could require special design considerations, such as measurement redundancy

  6. Detecting lower-mantle slabs beneath Asia and the Aleutians

    NASA Astrophysics Data System (ADS)

    Schumacher, L.; Thomas, C.

    2016-06-01

    To investigate the descend of subducted slabs we search for and analyse seismic arrivals that reflected off the surface of the slab. In order to distinguish between such arrivals and other seismic phases, we search for waves that reach a seismic array with a backazimuth deviating from the theoretical backazimuth of the earthquake. Source-receiver combinations are chosen in a way that their great circle paths do not intersect the slab region, hence the direct arrivals can serve as reference. We focus on the North and Northwest Pacific region by using earthquakes from Japan, the Philippines and the Hindu Kush area recorded at North American networks (e.g. USArray, Alaska and Canada). Using seismic array techniques for analysing the data and record information on slowness, backazimuth and traveltime of the observed out-of-plane arrivals we use these measurements to trace the wave back through a 1-D velocity model to its scattering/reflection location. We find a number of out-of-plane reflections. Assuming only single scattering, most out-of-plane signals have to travel as P-to-P phases and only a few as S-to-P phases, due to the length of the seismograms we processed. The located reflection points present a view of the 3-D structures within the mantle. In the upper mantle and the transition zone they correlate well with the edges of fast velocity regions in tomographic images. We also find reflection points in the mid- and lower mantle and their locations generally agree with fast velocities mapped by seismic tomography models suggesting that in the subduction regions we map, slabs enter the lower mantle. To validate our approach, we calculate and process synthetic seismograms for 3-D wave field propagation through a model containing a slab-like heterogeneity. We show, that depending on the source-receiver geometry relative to the reflection plane, it is indeed possible to observe and back-trace out-of-plane signals.

  7. A review on risk assessment techniques for hydraulic fracturing water and produced water management implemented in onshore unconventional oil and gas production.

    PubMed

    Torres, Luisa; Yadav, Om Prakash; Khan, Eakalak

    2016-01-01

    The objective of this paper is to review different risk assessment techniques applicable to onshore unconventional oil and gas production to determine the risks to water quantity and quality associated with hydraulic fracturing and produced water management. Water resources could be at risk without proper management of water, chemicals, and produced water. Previous risk assessments in the oil and gas industry were performed from an engineering perspective leaving aside important social factors. Different risk assessment methods and techniques are reviewed and summarized to select the most appropriate one to perform a holistic and integrated analysis of risks at every stage of the water life cycle. Constraints to performing risk assessment are identified including gaps in databases, which require more advanced techniques such as modeling. Discussions on each risk associated with water and produced water management, mitigation strategies, and future research direction are presented. Further research on risks in onshore unconventional oil and gas will benefit not only the U.S. but also other countries with shale oil and gas resources.

  8. A review on risk assessment techniques for hydraulic fracturing water and produced water management implemented in onshore unconventional oil and gas production.

    PubMed

    Torres, Luisa; Yadav, Om Prakash; Khan, Eakalak

    2016-01-01

    The objective of this paper is to review different risk assessment techniques applicable to onshore unconventional oil and gas production to determine the risks to water quantity and quality associated with hydraulic fracturing and produced water management. Water resources could be at risk without proper management of water, chemicals, and produced water. Previous risk assessments in the oil and gas industry were performed from an engineering perspective leaving aside important social factors. Different risk assessment methods and techniques are reviewed and summarized to select the most appropriate one to perform a holistic and integrated analysis of risks at every stage of the water life cycle. Constraints to performing risk assessment are identified including gaps in databases, which require more advanced techniques such as modeling. Discussions on each risk associated with water and produced water management, mitigation strategies, and future research direction are presented. Further research on risks in onshore unconventional oil and gas will benefit not only the U.S. but also other countries with shale oil and gas resources. PMID:26386446

  9. Slab tears and intermediate-depth seismicity

    USGS Publications Warehouse

    Meighan, Hallie E.; Ten Brink, Uri; Pulliam, Jay

    2013-01-01

    Active tectonic regions where plate boundaries transition from subduction to strike slip can take several forms, such as triple junctions, acute, and obtuse corners. Well-documented slab tears that are associated with high rates of intermediate-depth seismicity are considered here: Gibraltar arc, the southern and northern ends of the Lesser Antilles arc, and the northern end of Tonga trench. Seismicity at each of these locations occurs, at times, in the form of swarms or clusters, and various authors have proposed that each marks an active locus of tear propagation. The swarms and clusters start at the top of the slab below the asthenospheric wedge and extend 30–60 km vertically downward within the slab. We propose that these swarms and clusters are generated by fluid-related embrittlement of mantle rocks. Focal mechanisms of these swarms generally fit the shear motion that is thought to be associated with the tearing process.

  10. Seismological Features of the Subducting Slab Beneath the Kii Peninsula, Central Japan, Revealed by Receiver Functions

    NASA Astrophysics Data System (ADS)

    Shiomi, K.; Park, J.

    2007-12-01

    We report seismological evidence that the subducting Philippine Sea slab (PHS) beneath the Kii Peninsula, central Japan, can be divided into three segments. Offshore the Kii Peninsula, the "Tonankai" and "Nankai" fault segments suffer mega-thrust earthquakes that repeat every 100 to 150 years. The structure of the young, thin, contorted PHS is important to the seismo-tectonics in this region. We apply the receiver function (RF) analysis to 26 Hi-net short-period and 4 F-net broad-band seismographic stations. In the case that dipping velocity discontinuities and/or anisotropic media exist beneath seismometer, both radial RFs and transverse RFs contain useful information to estimate underground structure. For isotropic media with a dipping-slab interface, back- azimuthal variation in RFs depends largely on three parameters, the downdip azimuth, dip angle and the depth of the interface. We stack both radial and transverse RFs with allowance a time-shift caused by the dipping interface, searching for optimal parameters based on the grid-search technique at each station. At some stations located near the eastern coastline of the Kii Peninsula, the dip angle of the interface inferred from RF stacking is much steeper than that estimated by the local seismicity. This discrepancy arises from the interference of two slab-converted phases, suggesting a layer atop the slab. In these cases we refine the stack to distinguish two slab phases and estimate three parameters of each dipping interface separately. Two interfaces with the same dip direction and low dip angle are estimated at these stations, with depth difference near 6 km. Thus, the shallower interface may be related to the layer within the oceanic crust and the deeper one is the slab Moho. These double-layered interfaces are detected only at stations located up-dip of a belt-like distribution of non- volcanic low-frequency tremor. Comparing the interface dips estimated in this study with the direction of slab motion

  11. Transphyseal Distal Humerus Fracture.

    PubMed

    Abzug, Joshua; Ho, Christine Ann; Ritzman, Todd F; Brighton, Brian

    2016-01-01

    Transphyseal distal humerus fractures typically occur in children younger than 3 years secondary to birth trauma, nonaccidental trauma, or a fall from a small height. Prompt and accurate diagnosis of a transphyseal distal humerus fracture is crucial for a successful outcome. Recognizing that the forearm is not aligned with the humerus on plain radiographs may aid in the diagnosis of a transphyseal distal humerus fracture. Surgical management is most commonly performed with the aid of an arthrogram. Closed reduction and percutaneous pinning techniques similar to those used for supracondylar humerus fractures are employed. Cubitus varus caused by a malunion, osteonecrosis of the medial condyle, or growth arrest is the most common complication encountered in the treatment of transphyseal distal humerus fractures. A corrective lateral closing wedge osteotomy can be performed to restore a nearly normal carrying angle.

  12. The feeder system of the Toba supervolcano from the slab to the shallow reservoir

    NASA Astrophysics Data System (ADS)

    Koulakov, Ivan; Kasatkina, Ekaterina; Shapiro, Nikolai M.; Jaupart, Claude; Vasilevsky, Alexander; El Khrepy, Sami; Al-Arifi, Nassir; Smirnov, Sergey

    2016-07-01

    The Toba Caldera has been the site of several large explosive eruptions in the recent geological past, including the world's largest Pleistocene eruption 74,000 years ago. The major cause of this particular behaviour may be the subduction of the fluid-rich Investigator Fracture Zone directly beneath the continental crust of Sumatra and possible tear of the slab. Here we show a new seismic tomography model, which clearly reveals a complex multilevel plumbing system beneath Toba. Large amounts of volatiles originate in the subducting slab at a depth of ~150 km, migrate upward and cause active melting in the mantle wedge. The volatile-rich basic magmas accumulate at the base of the crust in a ~50,000 km3 reservoir. The overheated volatiles continue ascending through the crust and cause melting of the upper crust rocks. This leads to the formation of a shallow crustal reservoir that is directly responsible for the supereruptions.

  13. Fabrication of fracture-free nanoglassified substrates by layer-by-layer deposition with a paint gun technique for real-time monitoring of protein-lipid interactions.

    PubMed

    Linman, Matthew J; Culver, Sean P; Cheng, Quan

    2009-03-01

    New sensing materials that are robust, biocompatible, and amenable to array fabrication are vital to the development of novel bioassays. Herein we report the fabrication of ultrathin (ca. 5-8 nm) glass (silicate) layers on top of a gold surface for surface plasmon resonance (SPR) biosensing applications. The nanoglass layers are fabricated by layer-by-layer (LbL) deposition of poly(allylamine) hydrochloride (PAH) and sodium silicate (SiO(x)), followed by calcination at high temperature. To deposit these layers in a uniform and reproducible manner, we employed a high-volume, low-pressure (HVLP) paint gun technique that offers high precision and better control through pressurized nitrogen gas. The new substrates are stable in solution for a long period of time, and scanning electron microscopy (SEM) images confirm that these films are nearly fracture-free. In addition, atomic force microscopy (AFM) indicates that the surface roughness of the silicate layers is low (rms = 2 to 3 nm), similar to that of bare glass slides. By tuning the experimental parameters such as HVLP gun pressure and layers deposited, different surface morphology could be obtained as revealed by fluorescence microscopy and SEM images. To demonstrate the utility of these ultrathin, fracture-free substrates, lipid bilayer membranes composed of phosphorylated derivatives of phosphoinositides (PIs) were deposited on the new substrates for biosensing applications. Fluorescence recovery after photobleaching (FRAP) data indicated that these lipid components in the membranes were highly mobile. Furthermore, interactions of PtdIns(4,5)P2 and PtdIns(4)P lipids with their respective binding proteins were detected with high sensitivity by using SPR spectroscopy. This method of glass deposition can be combined with already well-developed surface chemistry for a range of planar glass assay applications, and the process is amenable to automation for mass production of nanometer thick silicate chips in a highly

  14. Arthroscopic fixation of an avulsion fracture of the tibia involving the posterior cruciate ligament: a modified technique in a series of 22 cases.

    PubMed

    Chen, L B; Wang, H; Tie, K; Mohammed, A; Qi, Y J

    2015-09-01

    A total of 22 patients with a tibial avulsion fracture involving the insertion of the posterior cruciate ligament (PCL) with grade II or III posterior laxity were reduced and fixed arthroscopically using routine anterior and double posteromedial portals. A double-strand Ethibond suture was inserted into the joint and wrapped around the PCL from anterior to posterior to secure the ligament above the avulsed bony fragment. Two tibial bone tunnels were created using the PCL reconstruction guide, aiming at the medial and lateral borders of the tibial bed. The ends of the suture were pulled out through the bone tunnels and tied over the tibial cortex between the openings of the tunnels to reduce and secure the bony fragment. Satisfactory reduction of the fracture was checked arthroscopically and radiographically. The patients were followed-up for a mean of 24.5 months (19 to 28). Bone union occurred six weeks post-operatively. At final follow-up, all patients had a negative posterior drawer test and a full range of movement. KT-1000 arthrometer examination showed that the mean post-operative side-to-side difference improved from 10.9 mm (standard deviation (sd) 0.7) pre-operatively to 1.5 mm (sd 0.6) (p = 0.001). The mean Tegner and the International Knee Documentation Committee scores improved significantly (p = 0.001). The mean Lysholm score at final follow-up was 92.0 (85 to 96). We conclude that this technique is convenient, reliable and minimally invasive and successfully restores the stability and function of the knee.

  15. Oceanic slab melting and mantle metasomatism.

    PubMed

    Scaillet, B; Prouteau, G

    2001-01-01

    Modern plate tectonic brings down oceanic crust along subduction zones where it either dehydrates or melts. Those hydrous fluids or melts migrate into the overlying mantle wedge trigerring its melting which produces arc magmas and thus additional continental crust. Nowadays, melting seems to be restricted to cases of young (< 50 Ma) subducted plates. Slab melts are silicic and strongly sodic (trondhjemitic). They are produced at low temperatures (< 1000 degrees C) and under water excess conditions. Their interaction with mantle peridotite produces hydrous metasomatic phases such as amphibole and phlogopite that can be more or less sodium rich. Upon interaction the slab melt becomes less silicic (dacitic to andesitic), and Mg, Ni and Cr richer. Virtually all exposed slab melts display geochemical evidence of ingestion of mantle material. Modern slab melts are thus unlike Archean Trondhjemite-Tonalite-Granodiorite rocks (TTG), which suggests that both types of magmas were generated via different petrogenetic pathways which may imply an Archean tectonic model of crust production different from that of the present-day, subduction-related, one. PMID:11838241

  16. A Simple Vertical Slab Gel Electrophoresis Apparatus.

    ERIC Educational Resources Information Center

    Carter, J. B.; And Others

    1983-01-01

    Describes an inexpensive, easily constructed, and safe vertical slab gel kit used routinely for sodium dodecyl sulphate-polyacrylamide gel electrophoresis research and student experiments. Five kits are run from a single transformer. Because toxic solutions are used, students are given plastic gloves and closely supervised during laboratory…

  17. Slab Ice Characterization on Martian Richardson Crater

    NASA Astrophysics Data System (ADS)

    Schmidt, F.; Andrieu, F.; Douté, S.

    2016-09-01

    We compare two models: granular and slab in order to study the ice properties in the Richardson crater using spectroscopy. Thanks to radiative transfer modeling, we determine compactness of CO2 ice, grain size, and abundances of water ice and dust.

  18. Oceanic slab melting and mantle metasomatism.

    PubMed

    Scaillet, B; Prouteau, G

    2001-01-01

    Modern plate tectonic brings down oceanic crust along subduction zones where it either dehydrates or melts. Those hydrous fluids or melts migrate into the overlying mantle wedge trigerring its melting which produces arc magmas and thus additional continental crust. Nowadays, melting seems to be restricted to cases of young (< 50 Ma) subducted plates. Slab melts are silicic and strongly sodic (trondhjemitic). They are produced at low temperatures (< 1000 degrees C) and under water excess conditions. Their interaction with mantle peridotite produces hydrous metasomatic phases such as amphibole and phlogopite that can be more or less sodium rich. Upon interaction the slab melt becomes less silicic (dacitic to andesitic), and Mg, Ni and Cr richer. Virtually all exposed slab melts display geochemical evidence of ingestion of mantle material. Modern slab melts are thus unlike Archean Trondhjemite-Tonalite-Granodiorite rocks (TTG), which suggests that both types of magmas were generated via different petrogenetic pathways which may imply an Archean tectonic model of crust production different from that of the present-day, subduction-related, one.

  19. Subducting slab structure and seismicity in the region of the 2010 M8.8 Maule earthquake: results from multi-scale P-wave tomography and relocation

    NASA Astrophysics Data System (ADS)

    Pesicek, J. D.; Zhang, H.; Thurber, C. H.; Lange, D.; Engdahl, E.; DeShon, H. R.

    2012-12-01

    We present a new tomographic model of the mantle in the area of the 2010 M8.8 Maule earthquake and surrounding region. Increased ray coverage provided by the aftershock data allows us to image the detailed subducting slab structure in the mantle, from the region of flat slab subduction north of the Maule rupture to the area of overlapping rupture between the 1960 M9.5 and the 2010 M8.8 events to the south. We have combined teleseismic primary and depth phase arrivals in the region with local arrivals to better constrain the locations of the teleseismically-recorded earthquakes in the region occurring since 1960. The updated locations are used to conduct multi-scale tomography employing a linear inversion method with a nested model design. The model reveals the detailed structure of the flat slab and its transition to a more moderately dipping slab in the Maule region. South of the Maule region, a steeply dipping relic slab is imaged from ~200-1000 km depth that is distinct from the moderately dipping slab above it and from the more northerly slab at similar depths. We interpret the images as revealing both horizontal and vertical tearing of the slab at ~38°S in order to explain the imaged pattern of slab anomalies in the southern portion of the model. In contrast, the transition from a horizontal to moderately subducting slab in the northern portion of the model is imaged as a continuous slab bend. We speculate that the tearing was most likely facilitated by a fracture zone in the downgoing plate or alternatively by a continental-scale terrane boundary in the overriding plate. Using this model as a reference model, we also present results from iterative multi-scale double-difference relocation and tomography. Preliminary relocations of teleseismically-recorded aftershocks show improved clustering and the results agree well with results from local studies in areas of overlap. Finally, inclusion of differential times for upgoing local and teleseismic depth phases

  20. Influence of Different Techniques of Laboratory Construction on the Fracture Resistance of Fiber-Reinforced Composite (FRC) Bridges.

    PubMed

    Ellakwa, Ayman E; Shortall, Adrian C; Marquis, Peter M

    2004-11-15

    The aim of the current investigation is to evaluate optimal pontic and retainer fiber positions for Polyethylene fiber-reinforced composite (FRC) restorations. In series I notch disc specimens were used to mimic loading cuspal regions of pontics. Four groups (n=15/group; codes A to D) were prepared from Artglass composite. Groups A to C were reinforced with polyethylene fibers, and group D was an unreinforced control. Fibers were positioned either around (A), beneath the notch (B), or at the disc base (C). Specimens were stored in distilled water at 37 degrees C for 24 h before testing to failure (CHS=1mm/min) in a universal testing machine. Mean torque to failure values ranked [P< 0.05; one-way analysis of variance (ANOVA)] as follows A = B > C = D. In series II five groups of three unit bridges (n =5/group; codes A to E) were prepared from Artglass dental composite without (group A) or with (groups B to E) different Connect fiber reinforcement locations/techniques. Bridges were cemented using 2 bond resin cement to a standardized substructure. After storage, as per series I, bridges were loaded mid-pontic region to failure. One-way ANOVA showed no significant (P=0.08) difference between test groups. The research hypothesis was that notched disc and 3 unit bridge test techniques would discriminate equally between fiber-reinforced specimens and an unreinforced composite control was rejected.

  1. Elbow Fractures

    MedlinePlus

    ... and held together with pins and wires or plates and screws. Fractures of the distal humerus (see ... doctor. These fractures usually require surgical repair with plates and/or screw, unless they are stable. SIGNS ...

  2. Mantle Response to a Slab Gap and Three-dimensional Slab Interaction in Central America

    NASA Astrophysics Data System (ADS)

    Jadamec, M. A.; Fischer, K. M.

    2013-12-01

    Seismically constrained global slab geometries suggest the Middle America-South American subduction system contains a gap on the order of 500 km separating the east-dipping Cocos and Nazca slabs at depth (Gudmundsson and Sambridge, 1998; Syracuse and Abers, 2006; Hayes et al., 2012). The location of the gap correlates with tectonic features impinging on the Pacific side of the Middle America trench, in particular the incoming young buoyant oceanic lithosphere and oceanic ridges associated with the Galapagos hotspot and Cocos-Nazca spreading center (Protti et al., 1994; Mann et al., 2007; Muller et al., 2008). Moreover, geochemical studies focusing on the arc chemistry in the Central American volcanic front argue for a slab window of some kind in this region (Johnston and Thorkelson, 1997; Abratis and Worner, 2001; Hoernle et al., 2008). We use high-resolution, three-dimensional (3D) geodynamic modeling of the Middle America-South American subduction system to investigate the role of the incoming young oceanic lithosphere and a gap between the Cocos and Nazca slabs in controlling mantle flow velocity and geochemical signatures beneath Central America. The geodynamic models are geographically referenced with the geometry and thermal structure for the overriding and subducting plates based on geological and geophysical observables and constructed with the multi-plate subduction generator code, SlabGenerator (Jadamec and Billen, 2010; Jadamec et al., 2012; Jadamec and Billen, 2012). The viscous flow simulations are solved using the mantle convection finite-element code, CitcomCU (Zhong, 2006), modified by Jadamec and Billen (2010) to take into account the experimentally derived flow law for olivine and allow for variable 3D plate interface geometries and magnitudes of inter-plate coupling. The 3D numerical models indicate the gap between the Cocos and Nazca slabs serves as a conduit for Pacific-Cocos mantle to pass into the Caribbean, with toroidal flow around the

  3. Use of nanoindentation technique for a better understanding of the fracture toughness of Strombus gigas conch shell

    SciTech Connect

    Romana, L.; Thomas, P.; Bilas, P.; Mansot, J.L.; Merrifiels, M.; Bercion, Y.; Aranda, D. Aldana

    2013-02-15

    In this work the nanochemical properties of the composite organomineral biomaterial constituting Strombus gigas conch shell are studied by means of dynamic mechanical analyses associated to nanoidentation technique. The measurements are performed on shell samples presenting different surface orientations relative to the growth axis of the conch shell. The influence of the organic component of the biomaterial on its nanomechanical properties is also investigated by studying fresh and dried S. gigas conch shells. Monocrystalline aragonite is used as a reference. For the understanding of nanochemical behaviour, special attention is paid to the pop in events observed on the load/displacement curves which results from nanofractures' initiation and propagation occuring during the load process. In order to better understand the mechanical properties systematic studies of the structure and morphology are performed using scanning electron microscopy, atomic force microscopy and X-ray diffractometry. The hardness and Young's modulus values measured on bio aragonite samples are close to those of the aragonite mineral standard. This surprising result shows that, H and E values are not related to the bio composition and lamellar structure of the bio aragonite. However, it was found that the organic layer and the micro architecture strongly influence the nanofracture initiation and propagation processes in the samples. Statistic study of the pop-in events can help to predict the macroscopic mechanical behaviour of the material. - Highlights: ► Nanomechanical properties of Strombus gigas conch shell ► Low influence of the crossed lamellar structure on H and E values at the nano scale ► Strong influence of the crossed lamellar on nanocracks initiation ► Correlation between mechanical behaviors at the macro and nano scales.

  4. Metatarsal fractures.

    PubMed

    Rammelt, Stefan; Heineck, Jan; Zwipp, Hans

    2004-09-01

    Metatarsal fractures are relatively common and if malunited, a frequent source of pain and disability. Nondisplaced fractures and fractures of the second to fourth metatarsal with displacement in the horizontal plane can be treated conservatively with protected weight bearing in a cast shoe for 4-6 weeks. In most displaced fractures, closed reduction can be achieved but maintenance of the reduction needs internal fixation. Percutaneous pinning is suitable for most fractures of the lesser metatarsals. Fractures with joint involvement and multiple fragments frequently require open reduction and plate fixation. Transverse fractures at the metaphyseal-diaphyseal junction of the fifth metatarsal ("Jones fractures") require an individualized approach tailored to the level of activity and time to union. Avulsion fractures of the fifth metatarsal bone are treated by open reduction and tension-band wiring or screw fixation if displaced more than 2 mm or with more that 30% of the joint involved. The metatarsals are the most common site of stress fractures, most of which are treated nonoperatively. Symptomatic posttraumatic deformities need adequate correction, in most cases by osteotomy across the former fracture site.

  5. Subduction zone earthquakes and stress in slabs

    NASA Technical Reports Server (NTRS)

    Vassiliou, M. S.; Hager, B. H.

    1988-01-01

    Simple viscous fluid models of subducting slabs are used to explain observations of the distribution of earthquakes as a function of depth and the orientation of stress axes of deep (greater than 300 km) and intermediate (70-300 km) earthquakes. Results suggest the following features in the distribution of earthquakes with depth: (1) an exponential decrease from shallow depths down to 250 to 300 km, (2) a minimum near 250 to 300 km, and (3) a deep peak below 300 km. Many shallow subducting slabs show only the first characteristic, while deeper extending regions tend to show all three features, with the deep peak varying in position and intensity. These data, combined with the results on the stress orientations of various-depth earthquakes, are consistent with the existence of a barrier of some sort at 670-km depth and a uniform viscosity mantle above this barrier.

  6. Slab photonic crystals with dimer colloid bases

    SciTech Connect

    Riley, Erin K.; Liddell Watson, Chekesha M.

    2014-06-14

    The photonic band gap properties for centered rectangular monolayers of asymmetric dimers are reported. Colloids in suspension have been organized into the phase under confinement. The theoretical model is inspired by the range of asymmetric dimers synthesized via seeded emulsion polymerization and explores, in particular, the band structures as a function of degree of lobe symmetry and degree of lobe fusion. These parameters are varied incrementally from spheres to lobe-tangent dimers over morphologies yielding physically realizable particles. The work addresses the relative scarcity of theoretical studies on photonic crystal slabs with vertical variation that is consistent with colloidal self-assembly. Odd, even and polarization independent gaps in the guided modes are determined for direct slab structures. A wide range of lobe symmetry and degree of lobe fusion combinations having Brillouin zones with moderate to high isotropy support gaps between odd mode band indices 3-4 and even mode band indices 1-2 and 2-3.

  7. The effect of subducting slabs in global shear wave tomography

    NASA Astrophysics Data System (ADS)

    Lu, Chang; Grand, Stephen P.

    2016-05-01

    Subducting slabs create strong short wavelength seismic anomalies in the upper mantle where much of Earth's seismicity is located. As such, they have the potential to bias longer wavelength seismic tomography models. To evaluate the effect of subducting slabs in global tomography, we performed a series of inversions using a global synthetic shear wave traveltime data set for a theoretical slab model based on predicted thermal anomalies within slabs. The spectral element method was applied to predict the traveltime anomalies produced by the 3-D slab model for paths corresponding to our current data used in actual tomography models. Inversion tests have been conducted first using the raw traveltime anomalies to check how well the slabs can be imaged in global tomography without the effect of earthquake mislocation. Our results indicate that most of the slabs can be identified in the inversion result but with smoothed and reduced amplitude. The recovery of the total mass anomaly in slab regions is about 88 per cent. We then performed another inversion test to investigate the effect of mislocation caused by subducting slabs. We found that source mislocation largely removes slab signal and significantly degrades the imaging of subducting slabs-potentially reducing the recovery of mass anomalies in slab regions to only 41 per cent. We tested two source relocation procedures-an iterative relocation inversion and joint relocation inversion. Both methods partially recover the true source locations and improve the inversion results, but the joint inversion method worked significantly better than the iterative method. In all of our inversion tests, the amplitudes of artefact structures in the lower mantle caused by the incorrect imaging of slabs (up to ˜0.5 per cent S velocity anomalies) are comparable to some large-scale lower-mantle heterogeneities seen in global tomography studies. Based on our inversion tests, we suggest including a-priori subducting slabs in the

  8. Implementing slab solar water heating system

    NASA Astrophysics Data System (ADS)

    Raveendran, S. K.; Shen, C. Q.

    2015-08-01

    Water heating contributes a significant part of energy consumption in typical household. One of the most employed technologies today that helps in reducing the energy consumption of water heating would be conventional solar water heating system. However, this system is expensive and less affordable by most family. The main objective of this project is to design and implement an alternative type of solar water heating system that utilize only passive solar energy which is known as slab solar water heating system. Slab solar water heating system is a system that heat up cold water using the solar radiance from the sun. The unique part of this system is that it does not require any form of electricity in order to operate. Solar radiance is converted into heat energy through convection method and cold water will be heated up by using conduction method [1]. The design of this system is governed by the criteria of low implementation cost and energy saving. Selection of material in the construction of a slab solar water heating system is important as it will directly affect the efficiency and performance of the system. A prototype has been built to realize the idea and it had been proven that this system was able to provide sufficient hot water supply for typical household usage at any given time.

  9. Convection in Slab and Spheroidal Geometries

    NASA Technical Reports Server (NTRS)

    Porter, David H.; Woodward, Paul R.; Jacobs, Michael L.

    2000-01-01

    Three-dimensional numerical simulations of compressible turbulent thermally driven convection, in both slab and spheroidal geometries, are reviewed and analyzed in terms of velocity spectra and mixing-length theory. The same ideal gas model is used in both geometries, and resulting flows are compared. The piecewise-parabolic method (PPM), with either thermal conductivity or photospheric boundary conditions, is used to solve the fluid equations of motion. Fluid motions in both geometries exhibit a Kolmogorov-like k(sup -5/3) range in their velocity spectra. The longest wavelength modes are energetically dominant in both geometries, typically leading to one convection cell dominating the flow. In spheroidal geometry, a dipolar flow dominates the largest scale convective motions. Downflows are intensely turbulent and up drafts are relatively laminar in both geometries. In slab geometry, correlations between temperature and velocity fluctuations, which lead to the enthalpy flux, are fairly independent of depth. In spheroidal geometry this same correlation increases linearly with radius over the inner 70 percent by radius, in which the local pressure scale heights are a sizable fraction of the radius. The effects from the impenetrable boundary conditions in the slab geometry models are confused with the effects from non-local convection. In spheroidal geometry nonlocal effects, due to coherent plumes, are seen as far as several pressure scale heights from the lower boundary and are clearly distinguishable from boundary effects.

  10. Fast Waves in Smooth Coronal Slab

    NASA Astrophysics Data System (ADS)

    Lopin, I.; Nagorny, I.

    2015-03-01

    This work investigates the effect of transverse density structuring in coronal slab-like waveguides on the properties of fast waves. We generalized previous results obtained for the exponential and Epstein profiles to the case of an arbitrary transverse density distribution. The criteria are given to determine the possible (trapped or leaky) wave regime, depending on the type of density profile function. In particular, there are plasma slabs with transverse density structuring that support pure trapped fast waves for all wavelengths. Their phase speed is nearly equal to the external Alfvén speed for the typical parameters of coronal loops. Our findings are obtained on the basis of Kneser’s oscillation theorem. To confirm the results, we analytically solved the wave equation evaluated at the cutoff point and the original wave equation for particular cases of transverse density distribution. We also used the WKB method and obtained approximate solutions of the wave equation at the cutoff point for an arbitrary transverse density profile. The analytic results were supplemented by numerical solutions of the obtained dispersion relations. The observed high-quality quasi-periodic pulsations of flaring loops are interpreted in terms of the trapped fundamental fast-sausage mode in a slab-like coronal waveguide.

  11. Insufficiency fractures of the sacrum

    SciTech Connect

    Cooper, K.L.; Beabout, J.W.; Swee, R.G.

    1985-07-01

    Insufficiency stress fractures may occur in the sacrum after radiation therapy or secondary to postmenopausal or steroid-induced osteoporosis. These fractures are often either overlooked or confused both clinically and radiographically with metastatic disease. Findings on plain films and conventional tomograms are often subtle. Radionuclide bone scans show a characteristic distribution of increased uptake. Computed tomography is the definitive technique for demonstrating the fractures.

  12. Combustion of solid fuel slabs with gaseous oxygen in a hybrid motor analog

    NASA Technical Reports Server (NTRS)

    Chiaverini, Martin J.; Harting, George C.; Lu, Yeu-Cherng; Kuo, Kenneth K.; Serin, Nadir; Johnson, David K.

    1995-01-01

    Using a high-pressure, two-dimensional hybrid motor, an experimental investigation was conducted on fundamental processes involved in hybrid rocket combustion. HTPB (Hydroxyl-terminated Polybutadiene) fuel cross-linked with diisocyanate was burned with gaseous oxygen (GOX) under various operating conditions. Large-amplitude pressure oscillations were encountered in earlier test runs. After identifying the source of instability and decoupling the GOX feed-line system and combustion chamber, the pressure oscillations were drastically reduced from plus or minus 20% of the localized mean pressure to an acceptable range of plus or minus 1.5%. Embedded fine--wire thermocouples indicated that the surface temperature of the burning fuel was around 1000 K depending upon axial locations and operating conditions. Also, except near the leading edge region, the subsurface thermal wave profiles in the upstream locations are thicker than those in the downstream locations since the solid-fuel regression rate, in general, increases with distance along the fuel slab. The recovered solid fuel slabs in the laminar portion of the boundary layer exhibited smooth surfaces, indicating the existence of a liquid melt layer on the burning fuel surface in the upstream region. After the transition section, which displayed distinct transverse striations, the surface roughness pattern became quite random and very pronounced in the downstream turbulent boundary-layer region. Both real-time X-ray radiography and ultrasonic pulse echo techniques were used to determine the instantaneous web thicknesses and instantaneous solid-fuel regression rates over certain portions of the fuel slabs. Globally averaged and axially dependent but time-averaged regression rates were also obtained and presented. Several tests were conducted using, simultaneously, one translucent fuel slab and one fuel slab processed with carbon black powder. The addition of carbon black did not affect the measured regression rates or

  13. Combustion of solid fuel slabs with gaseous oxygen in a hybrid motor analog

    NASA Technical Reports Server (NTRS)

    Chiaverini, Martin J.; Harting, George C.; Lu, Yeu-Cherng; Kuo, Kenneth K.; Serin, Nadir; Johnson, David K.

    1995-01-01

    Using a high-pressure, two-dimensional hybrid motor, an experimental investigation was conducted on fundamental processes involved in hybrid rocket combustion. HTPB (Hydroxyl-terminated- Polybutadiene) fuel cross linked with diisocyanate was burned with GOX under various operating conditions. Large amplitude pressure oscillations were encountered in earlier test runs. After identifying the source of instability and decoupling the GOX feed line system and combustion chamber, the pressure oscillations were drastically reduced from +/- 20% of the localized mean pressure to an acceptable range of +/- 1.5%. Embedded fine-wire thermocouples indicated that the surface temperature of the burning fuel was around 1000 K depending upon axial locations and operating conditions. Also, except near the leading-edge region, the subsurface thermal wave profiles in the upstream locations arc thicker than those in the downstream locations since the solid-fuel regression rate, in general, increases with distance along the fuel slab. The recovered solid fuel slabs in the laminar portion of the boundary layer exhibited smooth surfaces, indicating the existence of a liquid melt layer on the burning fuel surface in the upstream region. After the transition section, which displayed distinct transverse striations, the surface roughness pattern became quite random and very pronounced in the downstream turbulent boundary-layer region. Both real time X-ray radiography and ultrasonic pulse-echo techniques were used to determine the instantaneous web thicknesses and instantaneous solid-fuel regression rates over certain portions of the fuel slabs. Globally averaged and axially dependent but time-averaged regression rates were also obtained and presented. Several tests were conducted using, simultaneously, one translucent fuel slab and one fuel slab processed with carbon black powder. The addition of carbon black did not affect the measured regression rates or surface temperatures in comparison

  14. A Numerical Method for Obtaining Monoenergetic Neutron Flux Distributions and Transmissions in Multiple-Region Slabs

    NASA Technical Reports Server (NTRS)

    Schneider, Harold

    1959-01-01

    This method is investigated for semi-infinite multiple-slab configurations of arbitrary width, composition, and source distribution. Isotropic scattering in the laboratory system is assumed. Isotropic scattering implies that the fraction of neutrons scattered in the i(sup th) volume element or subregion that will make their next collision in the j(sup th) volume element or subregion is the same for all collisions. These so-called "transfer probabilities" between subregions are calculated and used to obtain successive-collision densities from which the flux and transmission probabilities directly follow. For a thick slab with little or no absorption, a successive-collisions technique proves impractical because an unreasonably large number of collisions must be followed in order to obtain the flux. Here the appropriate integral equation is converted into a set of linear simultaneous algebraic equations that are solved for the average total flux in each subregion. When ordinary diffusion theory applies with satisfactory precision in a portion of the multiple-slab configuration, the problem is solved by ordinary diffusion theory, but the flux is plotted only in the region of validity. The angular distribution of neutrons entering the remaining portion is determined from the known diffusion flux and the remaining region is solved by higher order theory. Several procedures for applying the numerical method are presented and discussed. To illustrate the calculational procedure, a symmetrical slab ia vacuum is worked by the numerical, Monte Carlo, and P(sub 3) spherical harmonics methods. In addition, an unsymmetrical double-slab problem is solved by the numerical and Monte Carlo methods. The numerical approach proved faster and more accurate in these examples. Adaptation of the method to anisotropic scattering in slabs is indicated, although no example is included in this paper.

  15. Closed reduction of the mandibular fracture.

    PubMed

    Blitz, Meredith; Notarnicola, Kurt

    2009-03-01

    The search for the ideal method of treatment for mandibular fractures has continued for thousands of years. These injuries have unique and problematic features for adequate reliable wound healing. Oral and maxillofacial surgeons must learn and master several techniques for mandibular fracture treatment. The age-old successful management of these injuries using closed reduction techniques always should be considered when mandibular trauma presents. The closed reduction remains a mainstay of mandibular fracture treatment. An adequate knowledge of anatomy, multiple closed reduction techniques, and the physiology of fracture healing must be adequately understood and technically mastered by the oral and maxillofacial surgical team for the present and future of mandibular fracture management.

  16. Viscous Dissipation and Criticality of Subducting Slabs

    NASA Astrophysics Data System (ADS)

    Riedel, Mike; Karato, Shun; Yuen, Dave

    2016-04-01

    Rheology of subducting lithosphere appears to be complicated. In the shallow part, deformation is largely accomodated by brittle failure, whereas at greater depth, at higher confining pressures, ductile creep is expected to control slab strength. The amount of viscous dissipation ΔQ during subduction at greater depth, as constrained by experimental rock mechanics, can be estimated on the basis of a simple bending moment equation [1,2] 2ɛ˙0(z) ∫ +h/2 2 M (z) = h ṡ -h/2 4μ(y,z)y dy , (1) for a complex multi-phase rheology in the mantle transition zone, including the effects of a metastable phase transition as well as the pressure, temperature, grain-size and stress dependency of the relevant creep mechanisms; μ is here the effective viscosity and ɛ˙0(z) is a (reference) strain rate. Numerical analysis shows that the maximum bending moment, Mcrit, that can be sustained by a slab is of the order of 1019 Nm per m according to Mcrit˜=σp ∗h2/4, where σp is the Peierl's stress limit of slab materials and h is the slab thickness. Near Mcrit, the amount of viscous dissipation grows strongly as a consequence of a lattice instability of mantle minerals (dislocation glide in olivine), suggesting that thermo-mechanical instabilities become prone to occur at places where a critical shear-heating rate is exceeded, see figure. This implies that the lithosphere behaves in such cases like a perfectly plastic solid [3]. Recently available detailed data related to deep seismicity [4,5] seems to provide support to our conclusion. It shows, e.g., that thermal shear instabilities, and not transformational faulting, is likely the dominating mechanism for deep-focus earthquakes at the bottom of the transition zone, in accordance with this suggested "deep criticality" model. These new findings are therefore briefly outlined and possible implications are discussed. References [1] Riedel, M. R., Karato, S., Yuen, D. A. Criticality of Subducting Slabs. University of Minnesota

  17. Viscous Dissipation and Criticality of Subducting Slabs

    NASA Astrophysics Data System (ADS)

    Riedel, Mike; Karato, Shun; Yuen, Dave

    2016-04-01

    Rheology of subducting lithosphere appears to be complicated. In the shallow part, deformation is largely accomodated by brittle failure, whereas at greater depth, at higher confining pressures, ductile creep is expected to control slab strength. The amount of viscous dissipation ΔQ during subduction at greater depth, as constrained by experimental rock mechanics, can be estimated on the basis of a simple bending moment equation [1,2] 2ɛ˙0(z) ∫ +h/2 2 M (z) = h ṡ ‑h/2 4μ(y,z)y dy , (1) for a complex multi-phase rheology in the mantle transition zone, including the effects of a metastable phase transition as well as the pressure, temperature, grain-size and stress dependency of the relevant creep mechanisms; μ is here the effective viscosity and ɛ˙0(z) is a (reference) strain rate. Numerical analysis shows that the maximum bending moment, Mcrit, that can be sustained by a slab is of the order of 1019 Nm per m according to Mcrit˜=σp ∗h2/4, where σp is the Peierl's stress limit of slab materials and h is the slab thickness. Near Mcrit, the amount of viscous dissipation grows strongly as a consequence of a lattice instability of mantle minerals (dislocation glide in olivine), suggesting that thermo-mechanical instabilities become prone to occur at places where a critical shear-heating rate is exceeded, see figure. This implies that the lithosphere behaves in such cases like a perfectly plastic solid [3]. Recently available detailed data related to deep seismicity [4,5] seems to provide support to our conclusion. It shows, e.g., that thermal shear instabilities, and not transformational faulting, is likely the dominating mechanism for deep-focus earthquakes at the bottom of the transition zone, in accordance with this suggested "deep criticality" model. These new findings are therefore briefly outlined and possible implications are discussed. References [1] Riedel, M. R., Karato, S., Yuen, D. A. Criticality of Subducting Slabs. University of Minnesota

  18. Tectonic controls on earthquake size distribution and seismicity rate: slab buoyancy and slab bending

    NASA Astrophysics Data System (ADS)

    Nishikawa, T.; Ide, S.

    2014-12-01

    There are clear variations in maximum earthquake magnitude among Earth's subduction zones. These variations have been studied extensively and attributed to differences in tectonic properties in subduction zones, such as relative plate velocity and subducting plate age [Ruff and Kanamori, 1980]. In addition to maximum earthquake magnitude, the seismicity of medium to large earthquakes also differs among subduction zones, such as the b-value (i.e., the slope of the earthquake size distribution) and the frequency of seismic events. However, the casual relationship between the seismicity of medium to large earthquakes and subduction zone tectonics has been unclear. Here we divide Earth's subduction zones into over 100 study regions following Ide [2013] and estimate b-values and the background seismicity rate—the frequency of seismic events excluding aftershocks—for subduction zones worldwide using the maximum likelihood method [Utsu, 1965; Aki, 1965] and the epidemic type aftershock sequence (ETAS) model [Ogata, 1988]. We demonstrate that the b-value varies as a function of subducting plate age and trench depth, and that the background seismicity rate is related to the degree of slab bending at the trench. Large earthquakes tend to occur relatively frequently (lower b-values) in shallower subduction zones with younger slabs, and more earthquakes occur in subduction zones with deeper trench and steeper dip angle. These results suggest that slab buoyancy, which depends on subducting plate age, controls the earthquake size distribution, and that intra-slab faults due to slab bending, which increase with the steepness of the slab dip angle, have influence on the frequency of seismic events, because they produce heterogeneity in plate coupling and efficiently inject fluid to elevate pore fluid pressure on the plate interface. This study reveals tectonic factors that control earthquake size distribution and seismicity rate, and these relationships between seismicity and

  19. Technique de Blount dans le traitement des fractures supra condyliennes du coude chez l'enfant: à propos de 68 cas

    PubMed Central

    Chagou, Aniss; Rhanim, Abdelkarim; Zanati, Rachid; Kharmaz, Mohammed; Lamrani, Moulay Omar; Berrada, Mohammed Saleh; El Yaacoubi, Moradh; Ettaybi, Fouad

    2014-01-01

    La fracture de la palette humérale est la plus fréquente des fractures du coude de l'enfant. La méthode de BLOUNT, constitue une perspective thérapeutique longtemps connue. Elle consiste en une réduction sous contrôle scopique de la fracture et une contention en hyper flexion du coude. Notre série a porté sur l’étude de 68 cas de fractures supra condyliennes chez des enfants traités dans le service des urgences chirurgicales pédiatriques de l'hôpital d'enfant de Rabat entre janvier 2009 et janvier 2012. Nous comparons nos résultats avec les données de la littérature. PMID:25667714

  20. Vertebroplasty and kyphoplasty--a systematic review of cement augmentation techniques for osteoporotic vertebral compression fractures compared to standard medical therapy.

    PubMed

    Robinson, Yohan; Olerud, Claes

    2012-05-01

    After more than two decades the treatment effect of cement augmentation of osteoporotic vertebral compression fractures (VCF) has now been questioned by two blinded randomised placebo-controlled trials. Thus many practitioners are uncertain on the recommendation for cement augmentation techniques in elderly patients with osteoporotic VCF. This systematic review analyses randomised controlled trials on vertebroplasty and kyphoplasty to provide an overview on the current evidence. From an electronic database research 8 studies could be identified meeting our inclusion criteria of osteoporotic VCF in elderly (age>60 years), treatment with vertebroplasty or kyphoplasty, controlled with placebo or standard medical therapy, quality of life, function, or pain as primary parameter, and randomisation. Only two studies were properly blinded using a sham-operation as control. The other studies were using a non-surgical treatment control group. Further possible bias may be caused by manufacturer involvement in financing of three published RCT. There is level Ib evidence that vertebroplasty is no better than placebo, which is conflicting with the available level IIb evidence that there is a positive short-term effect of cement augmentation compared to standard medical therapy with regard to QoL, function and pain. Kyphoplasty is not superior to vertebroplasty with regard to pain, but with regard to VCF reduction (evidence level IIb). Kyphoplasty is probably not cost-effective (evidence level IIb), and vertebroplasty has not more than short-term cost-effectiveness (evidence level IV). Vertebroplasty and kyphoplasty cannot be recommended as standard treatment for osteoporotic VCF. Ongoing sham-controlled trials may provide further evidence in this regard.

  1. Seismic evidence for fragmentation of the Cocos slab in central Mexico

    NASA Astrophysics Data System (ADS)

    Dougherty, S. L.; Clayton, R. W.; Helmberger, D. V.

    2011-12-01

    The fine-scale seismic structure of the central Mexico subduction zone, particularly the interface between the slab and overriding plate, is studied using shallow (~40-90 km) intraslab earthquakes of moderate magnitude (M4-6). Regional waveforms from the contemporaneous Middle America Subduction Experiment (MASE) and Mapping the Rivera Subduction Zone (MARS) seismic arrays are complicated and contain detailed information about the subduction zone structure. Identification of seismic phases, their arrival times, and any possible complexities in their waveshapes provide evidence of lateral variations in structure. The detailed waveform information obtained is used to model the structure of the subducted plates, particularly along the transition from flat to normal subduction, where recent studies have shown evidence for possible slab tearing along the eastern projection of the Orozco Fracture Zone (OFZ). The lateral extent of a thin low velocity layer imaged atop the subducted Cocos plate in recent studies along the MASE array is examined here using the combined MASE and MARS waveforms. We find an edge to this low velocity layer which is coincident with the western boundary of the projected OFZ region. We use forward modeling of the 2D structure of the subducted Rivera and Cocos plates using a finite-difference algorithm in order to provide constraints on the thickness, velocity, and geometry of each slab's shallow seismic structure in this region. This modeling shows that the best approximation to the observed seismograms is obtained when there is an edge to the low velocity layer coincident with the western boundary of the projected OFZ region. Coupled with the results of recent plate motion studies which show that the Cocos plate north of the OFZ moves differently than that south of the OFZ, we propose that the Cocos slab is currently fragmenting into a North Cocos plate and a South Cocos plate along the eastern projection of the OFZ. This tearing event may be a

  2. Numerical Simulation of 3D Hydraulic Fracturing Based on an Improved Flow-Stress-Damage Model and a Parallel FEM Technique

    NASA Astrophysics Data System (ADS)

    Li, L. C.; Tang, C. A.; Li, G.; Wang, S. Y.; Liang, Z. Z.; Zhang, Y. B.

    2012-09-01

    The failure mechanism of hydraulic fractures in heterogeneous geological materials is an important topic in mining and petroleum engineering. A three-dimensional (3D) finite element model that considers the coupled effects of seepage, damage, and the stress field is introduced. This model is based on a previously developed two-dimensional (2D) version of the model (RFPA2D-Rock Failure Process Analysis). The RFPA3D-Parallel model is developed using a parallel finite element method with a message-passing interface library. The constitutive law of this model considers strength and stiffness degradation, stress-dependent permeability for the pre-peak stage, and deformation-dependent permeability for the post-peak stage. Using this model, 3D modelling of progressive failure and associated fluid flow in rock are conducted and used to investigate the hydro-mechanical response of rock samples at laboratory scale. The responses investigated are the axial stress-axial strain together with permeability evolution and fracture patterns at various stages of loading. Then, the hydraulic fracturing process inside a rock specimen is numerically simulated. Three coupled processes are considered: (1) mechanical deformation of the solid medium induced by the fluid pressure acting on the fracture surfaces and the rock skeleton, (2) fluid flow within the fracture, and (3) propagation of the fracture. The numerically simulated results show that the fractures from a vertical wellbore propagate in the maximum principal stress direction without branching, turning, and twisting in the case of a large difference in the magnitude of the far-field stresses. Otherwise, the fracture initiates in a non-preferred direction and plane then turns and twists during propagation to become aligned with the preferred direction and plane. This pattern of fracturing is common when the rock formation contains multiple layers with different material properties. In addition, local heterogeneity of the rock

  3. Optimal scaling in ductile fracture

    NASA Astrophysics Data System (ADS)

    Fokoua Djodom, Landry

    This work is concerned with the derivation of optimal scaling laws, in the sense of matching lower and upper bounds on the energy, for a solid undergoing ductile fracture. The specific problem considered concerns a material sample in the form of an infinite slab of finite thickness subjected to prescribed opening displacements on its two surfaces. The solid is assumed to obey deformation-theory of plasticity and, in order to further simplify the analysis, we assume isotropic rigid-plastic deformations with zero plastic spin. When hardening exponents are given values consistent with observation, the energy is found to exhibit sublinear growth. We regularize the energy through the addition of nonlocal energy terms of the strain-gradient plasticity type. This nonlocal regularization has the effect of introducing an intrinsic length scale into the energy. We also put forth a physical argument that identifies the intrinsic length and suggests a linear growth of the nonlocal energy. Under these assumptions, ductile fracture emerges as the net result of two competing effects: whereas the sublinear growth of the local energy promotes localization of deformation to failure planes, the nonlocal regularization stabilizes this process, thus resulting in an orderly progression towards failure and a well-defined specific fracture energy. The optimal scaling laws derived here show that ductile fracture results from localization of deformations to void sheets, and that it requires a well-defined energy per unit fracture area. In particular, fractal modes of fracture are ruled out under the assumptions of the analysis. The optimal scaling laws additionally show that ductile fracture is cohesive in nature, i.e., it obeys a well-defined relation between tractions and opening displacements. Finally, the scaling laws supply a link between micromechanical properties and macroscopic fracture properties. In particular, they reveal the relative roles that surface energy and microplasticity

  4. Effect of Subducting Slabs in Global Shear Wave Tomography

    NASA Astrophysics Data System (ADS)

    Lu, C.; Grand, S. P.

    2015-12-01

    Subducting slabs represent strong short wavelength seismic anomalies in the upper mantle where much of Earth's seismicity is located. As such, they have the potential to bias longer wavelength seismic tomography models. To evaluate the effect of subducting slabs in global tomography, we performed a series of inversion tests using a global synthetic shear wave travel time dataset for a theoretical slab model based on predicted thermal anomalies within slabs. The spectral element method (SEM) was applied to predict the travel time anomalies produced by the 3D slab model for paths corresponding to our current data used in actual tomography models. Inversion tests have been conducted first using the raw travel time anomalies to check how well the slabs can be imaged in global tomography without the effect of mislocation. Our results indicate that most of the slabs can be identified in the inversion result but with smoothed and reduced amplitude. The recovery of the total mass anomaly in slab regions is about 84%. We then performed another inversion test to investigate the effect of mislocation caused by subducting slabs. We found that source mislocation significantly degrades the imaging of subducting slabs - potentially reducimg the recovery of mass anomalies in slab regions to only 39%. We tested two source relocation procedures - an iterative relocation inversion and joint relocation inversion. Both methods partially recover the true source locations and improve the inversion results, but the joint inversion method worked significantly better than the iterative method. In all of our inversion tests, the amplitude of artifact structures in the lower mantle caused by the incorrect imaging of slabs (up to ~0.5% S velocity anomalies) are comparable to large scale lower mantle heterogeneities seen in global tomography studies.

  5. Mechanisms of deep slab hydration: numerical modeling and implications

    NASA Astrophysics Data System (ADS)

    Faccenda, M.; Gerya, T.; Burlini, L.

    2009-12-01

    Water is a fundamental component of the Earth, affecting its internal structures and dynamics. Sea-water enters the subduction factory via slab hydration that occurs mainly at the trench and is subsequently released in the upper mantle wedge because of slab warming and de-hydration. In the last decades, the scientific research has focused mainly on geophysical processes related to the de-hydration of the slab. However, not much is known on how and to which extent the subducting oceanic plate get hydrated. In order to investigate hydration of the slab, we performed 2D numerical models of a spontaneously bending oceanic plate using I2ELVIS code that account for visco-elasto-plastic rheologies and where fluid flow is regulated by Darci’s law. At the outer rise, bending-related slab faulting occurs, providing a pathway for water percolation in the slab. Faults generally deep trenchward, but antithetic faults are also common. Downward deep fluid flow establishes during brittle extensional deformation at the trench outer rise producing strong variation of the tectonic pressure and causing sub-hydrostatic or even negative pressure gradients along bending related normal faults through which fluids are pumped. The results of the numerical experiment indicate that water can be transported down and stored in the bending area via serpentinization of the normal faults. Deep slab hydration has important implications for the rheological structure, seismicity and seismic anisotropy of the upper mantle because: 1) more water can be stored in the slab producing more enhanced weakening of the mantle wedge, 2) intermediate and deep intra-slab earthquakes can be triggered by slab de-hydration, 3) DHMS phases, able to bring fluids down to the transition zone and lower mantle, could form in the cold core of the slab, 4) the slab could acquire a strong anisotropic fabric responsible for the anisotropic patterns observed at subduction zones.

  6. Complex Fluids and Hydraulic Fracturing.

    PubMed

    Barbati, Alexander C; Desroches, Jean; Robisson, Agathe; McKinley, Gareth H

    2016-06-01

    Nearly 70 years old, hydraulic fracturing is a core technique for stimulating hydrocarbon production in a majority of oil and gas reservoirs. Complex fluids are implemented in nearly every step of the fracturing process, most significantly to generate and sustain fractures and transport and distribute proppant particles during and following fluid injection. An extremely wide range of complex fluids are used: naturally occurring polysaccharide and synthetic polymer solutions, aqueous physical and chemical gels, organic gels, micellar surfactant solutions, emulsions, and foams. These fluids are loaded over a wide range of concentrations with particles of varying sizes and aspect ratios and are subjected to extreme mechanical and environmental conditions. We describe the settings of hydraulic fracturing (framed by geology), fracturing mechanics and physics, and the critical role that non-Newtonian fluid dynamics and complex fluids play in the hydraulic fracturing process. PMID:27070765

  7. [Distal humerus fractures in children].

    PubMed

    Schneidmueller, D; Boettger, M; Laurer, H; Gutsfeld, P; Bühren, V

    2013-11-01

    Fractures of the distal humerus belong to the most common injuries of the upper arm in childhood. Most frequently occurring is the supracondylar fracture of the distal humerus. In these cases and in the second most common epicondylar fractures, the metaphysis is affected and these fractures are therefore extra-articular. They have to be distinguished from articular fractures regarding therapy and prognosis. The growth potential of the distal epiphysis is very limited as is the possibility of spontaneous correction so that major dislocations should not be left uncorrected. Unstable and especially dislocated articular fractures must be anatomically reconstructed employing various osteosynthetic techniques, mostly combined with immobilization. Insufficient reconstruction, growth disturbance and non-union can result in axial deformities, such as cubitus valgus and varus, restriction of motion, pain and nerve palsy.

  8. Complex Fluids and Hydraulic Fracturing.

    PubMed

    Barbati, Alexander C; Desroches, Jean; Robisson, Agathe; McKinley, Gareth H

    2016-06-01

    Nearly 70 years old, hydraulic fracturing is a core technique for stimulating hydrocarbon production in a majority of oil and gas reservoirs. Complex fluids are implemented in nearly every step of the fracturing process, most significantly to generate and sustain fractures and transport and distribute proppant particles during and following fluid injection. An extremely wide range of complex fluids are used: naturally occurring polysaccharide and synthetic polymer solutions, aqueous physical and chemical gels, organic gels, micellar surfactant solutions, emulsions, and foams. These fluids are loaded over a wide range of concentrations with particles of varying sizes and aspect ratios and are subjected to extreme mechanical and environmental conditions. We describe the settings of hydraulic fracturing (framed by geology), fracturing mechanics and physics, and the critical role that non-Newtonian fluid dynamics and complex fluids play in the hydraulic fracturing process.

  9. Hybrid slab-microchannel gel electrophoresis system

    DOEpatents

    Balch, Joseph W.; Carrano, Anthony V.; Davidson, James C.; Koo, Jackson C.

    1998-01-01

    A hybrid slab-microchannel gel electrophoresis system. The hybrid system permits the fabrication of isolated microchannels for biomolecule separations without imposing the constraint of a totally sealed system. The hybrid system is reusable and ultimately much simpler and less costly to manufacture than a closed channel plate system. The hybrid system incorporates a microslab portion of the separation medium above the microchannels, thus at least substantially reducing the possibility of non-uniform field distribution and breakdown due to uncontrollable leakage. A microslab of the sieving matrix is built into the system by using plastic spacer materials and is used to uniformly couple the top plate with the bottom microchannel plate.

  10. Photonic crystal slab quantum cascade detector

    NASA Astrophysics Data System (ADS)

    Reininger, Peter; Schwarz, Benedikt; Harrer, Andreas; Zederbauer, Tobias; Detz, Hermann; Maxwell Andrews, Aaron; Gansch, Roman; Schrenk, Werner; Strasser, Gottfried

    2013-12-01

    In this Letter, we demonstrate the design, fabrication, and characterization of a photonic crystal slab quantum cascade detector (PCS-QCD). By employing a specifically designed resonant cavity, the performance of the photodetector is improved in three distinct ways. The PCS makes the QCD sensitive to surface normal incident light. It resonantly enhances the photon lifetime inside the active zone, thus increasing the photocurrent significantly. And, the construction form of the device inherently decreases the noise. Finally, we compare the characteristics of the PCS-QCD to a PCS - quantum well infrared photodetector and outline the advantages for certain fields of applications.

  11. Numerical quadrature for slab geometry transport algorithms

    SciTech Connect

    Hennart, J.P.; Valle, E. del

    1995-12-31

    In recent papers, a generalized nodal finite element formalism has been presented for virtually all known linear finite difference approximations to the discrete ordinates equations in slab geometry. For a particular angular directions {mu}, the neutron flux {Phi} is approximated by a piecewise function Oh, which over each space interval can be polynomial or quasipolynomial. Here we shall restrict ourselves to the polynomial case. Over each space interval, {Phi} is a polynomial of degree k, interpolating parameters given by in the continuous and discontinuous cases, respectively. The angular flux at the left and right ends and the k`th Legendre moment of {Phi} over the cell considered are represented as.

  12. Automated inspection of hot steel slabs

    DOEpatents

    Martin, Ronald J.

    1985-01-01

    The disclosure relates to a real time digital image enhancement system for performing the image enhancement segmentation processing required for a real time automated system for detecting and classifying surface imperfections in hot steel slabs. The system provides for simultaneous execution of edge detection processing and intensity threshold processing in parallel on the same image data produced by a sensor device such as a scanning camera. The results of each process are utilized to validate the results of the other process and a resulting image is generated that contains only corresponding segmentation that is produced by both processes.

  13. Automated inspection of hot steel slabs

    DOEpatents

    Martin, R.J.

    1985-12-24

    The disclosure relates to a real time digital image enhancement system for performing the image enhancement segmentation processing required for a real time automated system for detecting and classifying surface imperfections in hot steel slabs. The system provides for simultaneous execution of edge detection processing and intensity threshold processing in parallel on the same image data produced by a sensor device such as a scanning camera. The results of each process are utilized to validate the results of the other process and a resulting image is generated that contains only corresponding segmentation that is produced by both processes. 5 figs.

  14. Photonic crystal slab quantum cascade detector

    SciTech Connect

    Reininger, Peter Schwarz, Benedikt; Harrer, Andreas; Zederbauer, Tobias; Detz, Hermann; Maxwell Andrews, Aaron; Gansch, Roman; Schrenk, Werner; Strasser, Gottfried

    2013-12-09

    In this Letter, we demonstrate the design, fabrication, and characterization of a photonic crystal slab quantum cascade detector (PCS-QCD). By employing a specifically designed resonant cavity, the performance of the photodetector is improved in three distinct ways. The PCS makes the QCD sensitive to surface normal incident light. It resonantly enhances the photon lifetime inside the active zone, thus increasing the photocurrent significantly. And, the construction form of the device inherently decreases the noise. Finally, we compare the characteristics of the PCS-QCD to a PCS - quantum well infrared photodetector and outline the advantages for certain fields of applications.

  15. Geothermal well stimulated using High Energy Gas Fracturing

    SciTech Connect

    Chu, T.Y.; Jacobson, R.D.; Warpinski, N.; Mohaupt, H.

    1987-01-01

    This paper reports the result of an experimental study of the High Energy Gas Fracturing (HEGF) technique for geothermal well stimulation. These experiments demonstrated that multiple fractures could be created to link a water-filled borehole with other fractures. The resulting fracture network and fracture interconnections were characterized by flow tests as well as mine back. Commercial oil field fracturing tools were used successfully in these experiments.

  16. Geothermal Well Stimulated Using High Energy Gas Fracturing

    SciTech Connect

    Chu, T.Y.; Jacobson, R.D.; Warpinski, N.; Mohaupt, Henry

    1987-01-20

    This paper reports the result of an experimental study of the High Energy Gas Fracturing (HEGF) technique for geothermal well stimulation. These experiments demonstrated that multiple fractures could be created to link a water-filled borehole with other fractures. The resulting fracture network and fracture interconnections were characterized by flow tests as well as mine back. Commercial oil field fracturing tools were used successfully in these experiments. 5 refs., 2 tabs., 5 figs.

  17. Teeth in the line of mandibular fractures.

    PubMed

    Spinnato, Gaetano; Alberto, Pamela L

    2009-03-01

    Many mandibular fractures occur through tooth sockets. The treatment plan for teeth in the line of fracture has evolved through the years because of the development of new antibiotics and fixation techniques. In this article we review the history and current studies and discuss treatment protocols for teeth in the line of mandibular fractures.

  18. MULTIPLE SETS OF TWIN SLABS ON THE RUN OUT. THE ...

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

    MULTIPLE SETS OF TWIN SLABS ON THE RUN OUT. THE RUN OUT INCLUDES THE TRAVELING TORCH WHICH CUTS SLABS TO DESIRED LENGTH, AN IDENTIFICATION SYSTEM TO INDICATE HEAT NUMBER AND TRACE IDENTITY OF EVERY SLAB, AND A DEBURRING DEVICE TO SMOOTH SLABS. AT LEFT OF ROLLS IS THE DUMMY BAR. DUMMY BAR IS INSERTED UP THROUGH CONTAINMENT SECTION INTO MOLD PRIOR TO START OF CAST. WHEN STEEL IS INTRODUCED INTO MOLD IT CONNECTS WITH BAR AS CAST BEGINS, AT RUN OUT DUMMY BAR DISCONNECTS AND IS STORED. - U.S. Steel, Fairfield Works, Continuous Caster, Fairfield, Jefferson County, AL

  19. MULTIPLE SETS OF TWIN SLABS ON THE RUN OUT. THE ...

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

    MULTIPLE SETS OF TWIN SLABS ON THE RUN OUT. THE RUN OUT INCLUDES THE TRAVELING TORCH WHICH CUTS SLABS TO DESIRED LENGTH, AN IDENTIFICATION SYSTEM TO INDICATE HEAT NUMBER AND TRACE IDENTITY OF EVERY SLAB, AND A DEBURRING DEVICE TO SMOOTH SLABS. AT LEFT OF ROLLS IS THE DUMMY BAR. DUMMY BAR IS INSERTED UP THROUGH CONTAINMENT SECTION INTO MOLD PRIOR TO START OF CAST. WHEN STEEL IS INTRODUCED INTO MOLD IT CONNECTS WITH BAR AS CAST BEGINS, AT RUN OUT DUMMY BAR DISCONNECTS AND IS STORED - U.S. Steel, Fairfield Works, Continuous Caster, Fairfield, Jefferson County, AL

  20. Thermally induced birefringence in Nd:YAG slab lasers

    SciTech Connect

    Ostermeyer, Martin; Mudge, Damien; Veitch, Peter J.; Munch, Jesper

    2006-07-20

    We study thermally induced birefringence in crystalline Nd:YAG zigzag slab lasers and the associated depolarization losses. The optimum crystallographic orientation of the zigzag slab within the Nd:YAG boule and photoelastic effects in crystalline Nd:YAG slabs are briefly discussed. The depolarization is evaluated using the temperature and stress distributions, calculated using a finite element model, for realistically pumped and cooled slabs of finite dimensions. Jones matrices are then used to calculate the depolarization of the zigzag laser mode. We compare the predictions with measurements of depolarization, and suggest useful criteria for the design of the gain media for such lasers.

  1. Pyrometer method for measuring slab temperature in a reheat furnace

    SciTech Connect

    Rudzki, E.M.; Jackson, R.W.; Martocci, A.P.

    1984-02-21

    A method and apparatus to measure the temperature of a slab in a reheat furnace with increased accuracy using either a single or dual pyrometer system through use of a multiplicity of temperature correction functions involving temperatures of slab and wall, distance between a pyrometer and the slab at which it is aimed, a ratio of air and fuel supplying the furnace heat and radiation interferences. The functions are chosen by a micro-processor in the system dependent on temperature differentials, emissivity setting of the pyrometer, target distance between pyrometer and slab, and air and fuel flow rates existing and fluctuating in the system.

  2. Sub-slab vs. Near-slab Soil Vapor Profiles at a Chlorinated Solvent Site (1)

    EPA Science Inventory

    A critical issue in assessing the vapor intrusion pathway is the distribution and migration of VOCs from the subsurface source to the near surface environment. Of particular importance is the influence of a slab. Therefore, EPA/ORD is funding a research program with the primary...

  3. Relative permeability through fractures

    SciTech Connect

    Diomampo, Gracel, P.

    2001-08-01

    The mechanism of two-phase flow through fractures is of importance in understanding many geologic processes. Currently, two-phase flow through fractures is still poorly understood. In this study, nitrogen-water experiments were done on both smooth and rough parallel plates to determine the governing flow mechanism for fractures and the appropriate methodology for data analysis. The experiments were done using a glass plate to allow visualization of flow. Digital video recording allowed instantaneous measurement of pressure, flow rate and saturation. Saturation was computed using image analysis techniques. The experiments showed that gas and liquid phases flow through fractures in nonuniform separate channels. The localized channels change with time as each phase path undergoes continues breaking and reforming due to invasion of the other phase. The stability of the phase paths is dependent on liquid and gas flow rate ratio. This mechanism holds true for over a range of saturation for both smooth and rough fractures. In imbibition for rough-walled fractures, another mechanism similar to wave-like flow in pipes was also observed. The data from the experiments were analyzed using Darcy's law and using the concept of friction factor and equivalent Reynold's number for two-phase flow. For both smooth- and rough-walled fractures a clear relationship between relative permeability and saturation was seen. The calculated relative permeability curves follow Corey-type behavior and can be modeled using Honarpour expressions. The sum of the relative permeabilities is not equal one, indicating phase interference. The equivalent homogeneous single-phase approach did not give satisfactory representation of flow through fractures. The graphs of experimentally derived friction factor with the modified Reynolds number do not reveal a distinctive linear relationship.

  4. Fatigue Fractures

    PubMed Central

    Morris, James M.

    1968-01-01

    Fatigue (or stress) fracture of bone in military recruits has been recognized for many years. Most often it is a metatarsal bone that is involved but the tarsal bones, calcaneus, tibia, fibula, femur, and pelvis are occasionally affected. Reports of such fractures in the ribs, ulna and vertebral bodies may be found in the literature. In recent years, there has been increasing awareness of the occurrence of fatigue fractures in the civilian population. Weekend sportsmen, athletes in an early phase of training, and persons engaged in unaccustomed, repetitive, vigorous activity are potential victims of such a fracture. The signs and symptoms, roentgenographic findings, treatment and etiology of fatigue fractures are dealt with in this presentation. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6. PMID:5652745

  5. Can we approach the gas-liquid critical point using slab simulations of two coexisting phases?

    NASA Astrophysics Data System (ADS)

    Goujon, Florent; Ghoufi, Aziz; Malfreyt, Patrice; Tildesley, Dominic J.

    2016-09-01

    In this paper, we demonstrate that it is possible to approach the gas-liquid critical point of the Lennard-Jones fluid by performing simulations in a slab geometry using a cut-off potential. In the slab simulation geometry, it is essential to apply an accurate tail correction to the potential energy, applied during the course of the simulation, to study the properties of states close to the critical point. Using the Janeček slab-based method developed for two-phase Monte Carlo simulations [J. Janec̆ek, J. Chem. Phys. 131, 6264 (2006)], the coexisting densities and surface tension in the critical region are reported as a function of the cutoff distance in the intermolecular potential. The results obtained using slab simulations are compared with those obtained using grand canonical Monte Carlo simulations of isotropic systems and the finite-size scaling techniques. There is a good agreement between these two approaches. The two-phase simulations can be used in approaching the critical point for temperatures up to 0.97 TC ∗ (T∗ = 1.26). The critical-point exponents describing the dependence of the density, surface tension, and interfacial thickness on the temperature are calculated near the critical point.

  6. Fracture dimensions in frac&pack stimulation

    SciTech Connect

    Fan, Y.; Economides, M.J.

    1995-12-31

    A model is introduced to predict dynamic fracture dimensions in frac&pack stimulation. Design aspects of the two-in-one step treatment techniques, required by soft and high-permeability reservoirs are discussed. A pressure-dependent leakoff model, based on the transient flow of a non-Newtonian fluid displacing a reservoir fluid has been developed and incorporated with fracture mechanics concepts to simulate the entire process of frac&pack treatments including fracture propagation, inflation, proppant packing and closure. Results obtained in this study indicate the considerable difference between traditional fracturing and frac&pack treatments. In the latter, fracture length is much less important than fracture conductivity. This work shows how to terminate the fracture growth at the appropriate time, and how to design frac&packs resulting in fracture widths several times larger than those for traditional fracturing.

  7. Bone fractures: assessment and management.

    PubMed

    Lim, L; Sirichai, P

    2016-03-01

    Severe dental traumatic injuries often involve the supporting bone and soft tissues. This article outlines the current concepts in the management of dentoalveolar fractures for the general dental practitioner with case reports to illustrate management principles and techniques. PMID:26923449

  8. Bone fractures: assessment and management.

    PubMed

    Lim, L; Sirichai, P

    2016-03-01

    Severe dental traumatic injuries often involve the supporting bone and soft tissues. This article outlines the current concepts in the management of dentoalveolar fractures for the general dental practitioner with case reports to illustrate management principles and techniques.

  9. Fracture in macro-molecules

    NASA Technical Reports Server (NTRS)

    Devries, K. L.

    1976-01-01

    Techniques available for the observation of molecular bond rupture during fracture of polymers are briefly outlined. Additional pertinent information can also often be inferred from microscopic and macroscopic measures.

  10. Plate deformation at depth under northern California: Slab gap or stretched slab?

    USGS Publications Warehouse

    ten Brink, U.S.; Shimizu, N.; Molzer, P.C.

    1999-01-01

    Plate kinematic interpretations for northern California predict a gap in the underlying subducted slab caused by the northward migration of the Pacific-North America-Juan de Fuca triple junction. However, large-scale decompression melting and asthenospheric upwelling to the base of the overlying plate within the postulated gap are not supported by geophysical and geochemical observations. We suggest a model for the interaction between the three plates which is compatible with the observations. In this 'slab stretch' model the Juan de Fuca plate under coastal northern California deforms by stretching and thinning to fill the geometrical gap formed in the wake of the northward migrating Mendocino triple junction. The stretching is in response to boundary forces acting on the plate. The thinning results in an elevated geothermal gradient, which may be roughly equivalent to a 4 Ma oceanic lithosphere, still much cooler than that inferred by the slab gap model. We show that reequilibration of this geothermal gradient under 20-30 km thick overlying plate can explain the minor Neogene volcanic activity, its chemical composition, and the heat flow. In contrast to northern California, geochemical and geophysical consequences of a 'true' slab gap can be observed in the California Inner Continental Borderland offshore Los Angeles, where local asthenospheric upwelling probably took place during the Miocene as a result of horizontal extension and rotation of the overlying plate. The elevated heat flow in central California can be explained by thermal reequilibration of the stalled Monterey microplate under the Coast Ranges, rather than by a slab gap or viscous shear heating in the mantle.

  11. Seeing lumps, sticks, and slabs in silhouettes.

    PubMed

    Willats, J

    1992-01-01

    Marr has suggested that we see three-dimensional (3-D) shapes in silhouettes because we make the implicit assumption that the viewed shapes are generalized cones. One difficulty with this suggestion is that it cannot deal with silhouettes of irregular 3-D shapes like clouds and trees; another is that it only applies to generalized cones with a relatively high length:width ratio. An alternative explanation, suggested by evidence from cross-cultural studies of language, from children's early speech, and from children's early drawings, is that the scene primitives actually used by humans are not generalized cones but 'lumps', 'sticks', and 'slabs', that is, primitives whose only shape properties are their relative extensions in 3-D space. In this paper it is proposed that the implicit assumption we make in interpreting silhouettes is that the extendedness of the silhouette reflects the extendedness of the viewed shape, so that a round region is seen as a lump and a long region is seen as a stick; and that such views seem "natural" because they are the views most likely to be encountered in normal environments. This account is more general than that of Marr because it explains how we interpret silhouettes of all kinds of 3-D shapes, even very irregular ones. Unlike Marr's account, it also deals with flat shapes like slabs and discs, and shows why it is difficult to see these shapes in silhouettes.

  12. Subduction in eastern Indonesia: how many slabs?

    NASA Astrophysics Data System (ADS)

    Milsom, John

    2001-08-01

    Seismicity associated with arc-continent collision in eastern Indonesia testifies to past north-directed subduction of Indian Ocean lithosphere beneath the Banda Sea. The complex patterns of deep seismicity have been cited as evidence for simultaneous south-directed subduction at the northern margin of the sea but this interpretation has not been universally accepted. Recently available recomputations of hypocentre locations have provided increased resolution of eastern Indonesian Wadati-Benioff Zones (WBZs). Shallow to intermediate depth seismic activity around the Banda Arc appears to support models involving subduction of two separate and distinct lithospheric slabs, but between 150 and 500 km the WBZ has a continuous 'shoehorn' shape. This shape confirms the presence of subducted lithosphere beneath Seram, in the north, as well as beneath Timor, in the south, is incompatible with independent subduction of two unconnected plates and implies rapid eastwards retreat of the subduction trace across a now vanished northern spur of the Indian Ocean. This 'roll-back' is unlikely to have been driven by local gravitational forces alone and may have been sustained by injection behind the Banda slab of asthenospheric material escaping from the Molucca Sea arc-arc collision.

  13. Radiative transfer model for contaminated rough slabs.

    PubMed

    Andrieu, François; Douté, Sylvain; Schmidt, Frédéric; Schmitt, Bernard

    2015-11-01

    We present a semi-analytical model to simulate the bidirectional reflectance distribution function (BRDF) of a rough slab layer containing impurities. This model has been optimized for fast computation in order to analyze massive hyperspectral data by a Bayesian approach. We designed it for planetary surface ice studies but it could be used for other purposes. It estimates the bidirectional reflectance of a rough slab of material containing inclusions, overlaying an optically thick media (semi-infinite media or stratified media, for instance granular material). The inclusions are assumed to be close to spherical and constituted of any type of material other than the ice matrix. It can be any other type of ice, mineral, or even bubbles defined by their optical constants. We assume a low roughness and we consider the geometrical optics conditions. This model is thus applicable for inclusions larger than the considered wavelength. The scattering on the inclusions is assumed to be isotropic. This model has a fast computation implementation and thus is suitable for high-resolution hyperspectral data analysis. PMID:26560577

  14. Fracture of distal end clavicle: A review

    PubMed Central

    Sambandam, Balaji; Gupta, Rajat; Kumar, Santosh; Maini, Lalit

    2014-01-01

    Management of fracture distal end clavicle has always puzzled the orthopaedic surgeons. Now-a-days with a relatively active lifestyle, patients want better results both cosmetically and functionally. Despite so much literature available for the management of this common fracture, there is no consensus regarding the gold standard treatment for this fracture. In this article, we reviewed the literature on various techniques of management for this fracture, both conservative as well as surgical, and their merits and demerits. PMID:25983473

  15. Laboratory Visualization of Hydraulic Fracture Propagation and Interaction with a Network of Preexisting Fractures

    NASA Astrophysics Data System (ADS)

    Nakagawa, S.; Kneafsey, T. J.; Borglin, S. E.

    2015-12-01

    We present optical visualization experiments of hydraulic fracture propagation within transparent rock-analogue samples containing a network of preexisting fractures. Natural fractures and heterogeneities in rock have a great impact on hydraulic fracture propagation and resulting improvements in reservoir permeability. In recent years, many sophisticated numerical simulations on hydraulic fracturing have been conducted. Laboratory experiments on hydraulic fracturing are often performed with acoustic emission (Micro Earthquake) monitoring, which allows detection and location of fracturing and fracture propagation. However, the detected fractures are not necessarily hydraulically produced fractures which provide permeable pathways connected to the injection (and production) well. The primary objectives of our visualization experiments are (1) to obtain quantitative visual information of hydraulic fracture propagation affected by pre-existing fractures and (2) to distinguish fractures activated by the perturbed stress field away from the injected fluid and hydraulically produced fractures. The obtained data are also used to develop and validate a new numerical modeling technique (TOUGH-RBSN [Rigid-Body-Spring-Network] model) for hydraulic fracturing simulations, which is presented in a companion paper. The experiments are conducted using transparent soda-lime glass cubes (10 cm × 10 cm × 10 cm) containing either (1) 3D laser-engraved artificial fractures and fracture networks or (2) a random network of fractures produced by rapid thermal quenching. The strength (and also the permeability for the latter) of the fractures can be altered to examine their impact on hydraulic fracturing. The cubes are subjected to true-triaxial stress within a polyaxial loading frame, and hydraulic fractures are produced by injecting fluids with a range of viscosity into an analogue borehole drilled in the sample. The visual images of developing fractures are obtained both through a port

  16. Fluid flow behavior through rock-slab micromodels in relation to other micromodels

    SciTech Connect

    Mahmood, S.M.

    1990-06-01

    A new technique was developed to visualize fluid movement and rock/fluid interaction in the pores of reservoir rocks. It consists of fabricating micromodels containing rock slabs of 3 millimeter thickness and using sensitive image acquisition, recording, and enhancement systems to perform time-and-motion analyses of high-speed events. Displacement experiments were performed using these rock-slab micromodels and two other types of micromodels: an etched-glass network model (HEG) and a chemically consolidated grain-packed (cryolite) model. The tests included several cycles of imbibition and drainage. Comprehensive steady-state tests were also performed in the two simplified (HEG and cryolite) models, which included two-phase and three-phase flows with gas/water, oil/water, and gas/oil/water systems. The results were compared to understand the scope and limitations of these micromodel techniques. 24 refs., 8 figs.

  17. Scattering of electromagnetic waves from a turbulent plasma slab.

    NASA Technical Reports Server (NTRS)

    Liu, C. H.

    1972-01-01

    Scattering of electromagnetic waves from a turbulent plasma slab is studied. Part of the effects of the multiple scattering is taken into account. The reflection coefficient is found to be increased and its variation with respect to the slab thickness is smoothed out by the random scattering.

  18. 42. PRESSING A SLAB OF CLAY ONTO A MOSAIC MOLD. ...

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

    42. PRESSING A SLAB OF CLAY ONTO A MOSAIC MOLD. THE MOLD, WHICH HAS A RAISED DESIGN, LEAVES AND OUTLINE IN THE SLAB, THE PIECES THUS DEFINED, ARE THEN CUT APART TO BE FIRED SEPARATELY AND REASSEMBLED. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  19. Advanced parameter retrievals for metamaterial slabs using an inhomogeneous model

    NASA Astrophysics Data System (ADS)

    Li Hou, Ling; Chin, Jessie Yao; Yang, Xin Mi; Lin, Xian Qi; Liu, Ruopeng; Xu, Fu Yong; Cui, Tie Jun

    2008-03-01

    The S-parameter retrieval has proved to be an efficient approach to obtain electromagnetic parameters of metamaterials from reflection and transmission coefficients, where a slab of metamaterial with finite thickness is regarded as a homogeneous medium slab with the same thickness [D. R. Smith and S. Schultz, Phys. Rev. B 65, 195104 (2002)]. However, metamaterial structures composed of subwavelength unit cells are different from homogeneous materials, and the conventional retrieval method is, under certain circumstances, not accurate enough. In this paper, we propose an advanced parameter retrieval method for metamaterial slabs using an inhomogeneous model. Due to the coupling effects of unit cells in a metamaterial slab, the roles of edge and inner cells in the slab are different. Hence, the corresponding equivalent medium parameters are different, which results in the inhomogeneous property of the metamaterial slab. We propose the retrievals of medium parameters for edge and inner cells from S parameters by considering two- and three-cell metamaterial slabs, respectively. Then we set up an inhomogeneous three-layer model for arbitrary metamaterial slabs, which is much more accurate than the conventional homogeneous model. Numerical simulations verify the above conclusions.

  20. Fracture Management

    MedlinePlus

    ... to hold the fracture in the correct position. • Fiberglass casting is lighter and stronger and the exterior ... with your physician if this occurs. • When a fiberglass cast is used in conjunction with a GORE- ...

  1. Pediatric foot fractures.

    PubMed

    Ribbans, William J; Natarajan, Ramanathan; Alavala, Sairam

    2005-03-01

    Fractures of the foot in children usually have a good prognosis and generally are treated nonoperatively. Displaced fractures of the talus and calcaneus and tarsometatarsal dislocations are rare in children and their outcome is generally good in the younger child. Older adolescents with these injuries need treatment similar to how an adult would be treated for the same injury in order to achieve a good result. Foot fractures in children may pose a diagnostic challenge particularly in the absence of obvious radiographic changes. Repeated clinical examination and judicious use of imaging techniques such as isotope bone scans and magnetic resonance imaging are needed to establish a diagnosis. Knowledge of the anatomy and significance of accessory bones of the foot and disorders of the growing foot skeleton are helpful in managing injuries of child's foot. In this study, we review common injuries of a child's foot and include a discussion on differential diagnosis.

  2. Separation of supercritical slab-fluids to form aqueous fluid and melt components in subduction zone magmatism.

    PubMed

    Kawamoto, Tatsuhiko; Kanzaki, Masami; Mibe, Kenji; Matsukage, Kyoko N; Ono, Shigeaki

    2012-11-13

    Subduction-zone magmatism is triggered by the addition of H(2)O-rich slab-derived components: aqueous fluid, hydrous partial melts, or supercritical fluids from the subducting slab. Geochemical analyses of island arc basalts suggest two slab-derived signatures of a melt and a fluid. These two liquids unite to a supercritical fluid under pressure and temperature conditions beyond a critical endpoint. We ascertain critical endpoints between aqueous fluids and sediment or high-Mg andesite (HMA) melts located, respectively, at 83-km and 92-km depths by using an in situ observation technique. These depths are within the mantle wedge underlying volcanic fronts, which are formed 90 to 200 km above subducting slabs. These data suggest that sediment-derived supercritical fluids, which are fed to the mantle wedge from the subducting slab, react with mantle peridotite to form HMA supercritical fluids. Such HMA supercritical fluids separate into aqueous fluids and HMA melts at 92 km depth during ascent. The aqueous fluids are fluxed into the asthenospheric mantle to form arc basalts, which are locally associated with HMAs in hot subduction zones. The separated HMA melts retain their composition in limited equilibrium with the surrounding mantle. Alternatively, they equilibrate with the surrounding mantle and change the major element chemistry to basaltic composition. However, trace element signatures of sediment-derived supercritical fluids remain more in the melt-derived magma than in the fluid-induced magma, which inherits only fluid-mobile elements from the sediment-derived supercritical fluids. Separation of slab-derived supercritical fluids into melts and aqueous fluids can elucidate the two slab-derived components observed in subduction zone magma chemistry. PMID:23112158

  3. Separation of supercritical slab-fluids to form aqueous fluid and melt components in subduction zone magmatism.

    PubMed

    Kawamoto, Tatsuhiko; Kanzaki, Masami; Mibe, Kenji; Matsukage, Kyoko N; Ono, Shigeaki

    2012-11-13

    Subduction-zone magmatism is triggered by the addition of H(2)O-rich slab-derived components: aqueous fluid, hydrous partial melts, or supercritical fluids from the subducting slab. Geochemical analyses of island arc basalts suggest two slab-derived signatures of a melt and a fluid. These two liquids unite to a supercritical fluid under pressure and temperature conditions beyond a critical endpoint. We ascertain critical endpoints between aqueous fluids and sediment or high-Mg andesite (HMA) melts located, respectively, at 83-km and 92-km depths by using an in situ observation technique. These depths are within the mantle wedge underlying volcanic fronts, which are formed 90 to 200 km above subducting slabs. These data suggest that sediment-derived supercritical fluids, which are fed to the mantle wedge from the subducting slab, react with mantle peridotite to form HMA supercritical fluids. Such HMA supercritical fluids separate into aqueous fluids and HMA melts at 92 km depth during ascent. The aqueous fluids are fluxed into the asthenospheric mantle to form arc basalts, which are locally associated with HMAs in hot subduction zones. The separated HMA melts retain their composition in limited equilibrium with the surrounding mantle. Alternatively, they equilibrate with the surrounding mantle and change the major element chemistry to basaltic composition. However, trace element signatures of sediment-derived supercritical fluids remain more in the melt-derived magma than in the fluid-induced magma, which inherits only fluid-mobile elements from the sediment-derived supercritical fluids. Separation of slab-derived supercritical fluids into melts and aqueous fluids can elucidate the two slab-derived components observed in subduction zone magma chemistry.

  4. Separation of supercritical slab-fluids to form aqueous fluid and melt components in subduction zone magmatism

    PubMed Central

    Kawamoto, Tatsuhiko; Kanzaki, Masami; Mibe, Kenji; Ono, Shigeaki

    2012-01-01

    Subduction-zone magmatism is triggered by the addition of H2O-rich slab-derived components: aqueous fluid, hydrous partial melts, or supercritical fluids from the subducting slab. Geochemical analyses of island arc basalts suggest two slab-derived signatures of a melt and a fluid. These two liquids unite to a supercritical fluid under pressure and temperature conditions beyond a critical endpoint. We ascertain critical endpoints between aqueous fluids and sediment or high-Mg andesite (HMA) melts located, respectively, at 83-km and 92-km depths by using an in situ observation technique. These depths are within the mantle wedge underlying volcanic fronts, which are formed 90 to 200 km above subducting slabs. These data suggest that sediment-derived supercritical fluids, which are fed to the mantle wedge from the subducting slab, react with mantle peridotite to form HMA supercritical fluids. Such HMA supercritical fluids separate into aqueous fluids and HMA melts at 92 km depth during ascent. The aqueous fluids are fluxed into the asthenospheric mantle to form arc basalts, which are locally associated with HMAs in hot subduction zones. The separated HMA melts retain their composition in limited equilibrium with the surrounding mantle. Alternatively, they equilibrate with the surrounding mantle and change the major element chemistry to basaltic composition. However, trace element signatures of sediment-derived supercritical fluids remain more in the melt-derived magma than in the fluid-induced magma, which inherits only fluid-mobile elements from the sediment-derived supercritical fluids. Separation of slab-derived supercritical fluids into melts and aqueous fluids can elucidate the two slab-derived components observed in subduction zone magma chemistry. PMID:23112158

  5. Flat slab deformation caused by interplate suction force

    NASA Astrophysics Data System (ADS)

    Ma, Yiran; Clayton, Robert W.

    2015-09-01

    We image the structure at the southern end of the Peruvian flat subduction zone, using receiver function and surface wave methods. The Nazca slab subducts to ~100 km depth and then remains flat for ~300 km distance before it resumes the dipping subduction. The flat slab closely follows the topography of the continental Moho above, indicating a strong suction force between the slab and the overriding plate. A high-velocity mantle wedge exists above the initial half of the flat slab, and the velocity resumes to normal values before the slab steepens again, indicating the resumption of dehydration and ecologitization. Two prominent midcrust structures are revealed in the 70 km thick crust under the Central Andes: molten rocks beneath the Western Cordillera and the underthrusting Brazilian Shield beneath the Eastern Cordillera.

  6. Lisfranc fractures.

    PubMed

    Wright, Amanda; Gerhart, Ann E

    2009-01-01

    Injuries of the tarsometatarsal, or Lisfranc, joint are rarely seen. Lisfranc fractures and fracture dislocations are among the most frequently misdiagnosed foot injuries in the emergency department. A misdiagnosed injury may have severe consequences including chronic pain and loss of foot biomechanics. Evaluation of a foot injury should include a high level of suspicion of a Lisfranc injury, and a thorough work-up is needed for correct diagnosis.

  7. The Role of Subducting Ridges in the Formation of Flat Slabs: Insights from the Peruvian Flat Slab

    NASA Astrophysics Data System (ADS)

    Knezevic Antonijevic, Sanja; Wagner, Lara; Kumar, Abhash; Beck, Susan; Long, Maureen; Zandt, George; Eakin, Caroline M.

    2015-04-01

    Flattening of the subducting plate is often used to explain various geological features removed far from the subducting margins, including basement-cored uplifts, the cessation of arc volcanism, ignimbrite flare-ups, and the formation of high plateaus and ore deposits [Humphreys et al., 2003; Gutscher et al., 2000; Rosenbaum et al., 2005, Kay and Mpodozis, 2001]. Today, flat slab subduction is observed in central Chile and Peru, representing the modern analogues to the immense paleo-flat slab that subducted beneath the North American continent during the Laramide orogeny (80-55 Ma) [English et al., 2003]. However, how flat slabs form and what controls their inboard and along-strike extent is still poorly understood. To better understand modern and paleo-flat slabs, we focus on the Peruvian flat slab, where the Nazca plate starts to bend at ~90 km depth and travels horizontally for several hundred kilometers beneath the South American plate. Earlier studies propose a correlation between the flat slab and the subducting Nazca Ridge that has been migrating to the south over the past 11 ~Ma [Hampel et al., 2004, Gutscher et al., 2003]. Combining 3D shear wave velocity structure and Rayleigh wave phase anisotropy between ~10° and 18° S, we find that the flat slab has the greatest inboard extent along the track of the subducting Nazca Ridge. North of the ridge track, where the flat slab was initially formed, the flat slab starts to sag, tear and re-initiate steep slab subduction, allowing inflow of warm asthenosphere. Based on our new constraints on the geometry of the subducted plate, we find that the subduction of buoyant oceanic features with overthickened oceanic crust plays a vital role in the formation of flat slabs. We further develop a model of temporal evolution of the Peruvian flab slab that forms as a result of the combined effects of the subducting ridge, trench retreat, and suction forces. Once the buoyant ridge subducts to ~90 km depth, it will fail to

  8. Lithosphere-Mantle Interactions Associated with Flat-Slab Subduction

    NASA Astrophysics Data System (ADS)

    Gerault, M.; Becker, T. W.; Husson, L.; Humphreys, E.

    2014-12-01

    Episodes of flat-slab subduction along the western margin of the Americas may have lead to the formation of intra-continental basins and seas, as well as mountain belts and continental plateaux. Here, we explore some of the consequences of a flat slab morphology, linking dynamic topography and stress patterns in continents to slab and mantle dynamics. Using a 2-D cylindrical code, we develop general models and apply them to the North and South America plates. The results are primarily controlled by the coupling along the slab-continent interface (due to geometry and viscosity), the viscosity of the mantle wedge, and the buoyancy of the subducted lithosphere. All models predict broad subsidence, large deviatoric stresses, and horizontal compression above the tip of the flat slab and the deep slab hinge. In models where the slab lays horizontally for hundreds of kilometers, overriding plate compression focuses on both ends of the flat segment, where normal-dip subduction exerts a direct downward pull. In between, a broad low-stress region gets uplifted proportionally to the amount of coupling between the slab and the continent. Anomalously buoyant seafloor enhances this effect but is not required. The downward bending of the flat slab extremities causes its upper part to undergo extension and the lower part to compress. These results have potential for explaining the existence of relatively undeformed, uplifted regions surrounded by mountain belts, such as in the western U.S. and parts of the Andes. Adequately modeling topography and stress in the unusual setting of southwestern Mexico requires a low-viscosity subduction interface and mantle wedge. Our results are only partially controlled by the buoyancy of the subducting plate, suggesting that the viscosity and the morphology of the slab are important, and that the often-used low resolution and "Stokeslet" models may be missing substantial effects.

  9. Hybrid slab-microchannel gel electrophoresis system

    DOEpatents

    Balch, J.W.; Carrano, A.V.; Davidson, J.C.; Koo, J.C.

    1998-05-05

    A hybrid slab-microchannel gel electrophoresis system is described. The hybrid system permits the fabrication of isolated microchannels for biomolecule separations without imposing the constraint of a totally sealed system. The hybrid system is reusable and ultimately much simpler and less costly to manufacture than a closed channel plate system. The hybrid system incorporates a microslab portion of the separation medium above the microchannels, thus at least substantially reducing the possibility of non-uniform field distribution and breakdown due to uncontrollable leakage. A microslab of the sieving matrix is built into the system by using plastic spacer materials and is used to uniformly couple the top plate with the bottom microchannel plate. 4 figs.

  10. Laser applications in machining slab materials

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoping

    1990-10-01

    Since the invention of the laser back in 1960, laser technology has been extensively applied in many fields of science and technology. These has been a history of nearly two decades of using lasers as an energy source in machining materials, such as cutting, welding, ruling and boring, among other operations. With the development of flexible automation in production, the advantages of laser machining have has grown more and more obvious. The combination of laser technology and computer science further promotes the enhancement and upgrading of laser machining and related equipment. At present, many countries are building high quality laser equipment for machining slab materials, such as the Coherent and Spectra Physics corporations in the United States, the Trumpf Corporation in West Germany, the Amada Corporation in Japan, and the Bystronic Corporation in Switzerland, among other companies.

  11. Pelvic Insufficiency Fractures

    PubMed Central

    O’Connor, Timothy J.

    2014-01-01

    Pelvic insufficiency fractures may occur in the absence of trauma or as a result of low-energy trauma in osteoporotic bone. With a growing geriatric population, the incidence of pelvic insufficiency fracture has increased over the last 3 decades and will continue to do so. These fractures can cause considerable pain, loss of independence, and economic burden to both the patient and the health care system. While many of these injuries are identified and treated based on plain radiographs, some remain difficult to diagnose. The role of advanced imaging in these cases is discussed. In addition to treating the fracture, medical comorbidities contributing to osteoporosis should be identified and corrected. Specific attention has been given to 25-OH serum vitamin D screening and repletion. Treatment generally consists of providing pain control and assisting patients with mobilization while allowing weight bearing as tolerated. In those unable to do so, invasive techniques such as sacroplasty as well as internal fixation may be beneficial. The role of operative fixation in insufficiency fractures is also discussed. PMID:26246940

  12. Macroscopic properties of fractured porous media

    NASA Astrophysics Data System (ADS)

    Thovert, J.; Mourzenko, V. V.; Adler, P. M.

    2007-12-01

    The determination of the local fields in fractured porous media is a challenging problem, because of the multiple scales that are involved and of the possible nonlinearity of the governing equations. The purpose of this paper is to provide an overall view of the numerical technique which has been used to solve numerous problems. It is based on a three-dimensional discrete description of the fracture network and of the embedding matrix. Any fracture network geometry, any type of boundary condition, and any distribution of the fracture and matrix properties can be addressed, without simplifying approximations. The first step is to mesh the fracture network as it is by triangles of a controlled size. This meshing by an advancing front technique is done successively for each fracture and the intersections between fractures are taken into account. Then, the space in between the fractures is meshed by tetrahedra by the advancing front technique again. The faces of the tetrahedra which are in contact with fractures, coincide with the corresponding triangles in these fractures. The performances of these meshing codes will be illustrated by a few examples. The second step consists in discretizing the conservation equations by the finite volume technique. Specific properties are given to each fracture such as a surface permeability or a joint rigidity. This general technique has been applied to the basic and most important properties of fracture networks and of fractured porous media (1). These properties are single and two phase flows, wether they are accompagnied or not by dispersion of a solute and mechanical properties possibly coupled with flow. These applications will be briefly illustrated by some examples, including when possible comparison with real data. Ref: (1) P.M. Adler, V.V. Mourzenko, J.-F. Thovert, I. Bogdanov, in Dynamics of fluids and transport in fractured rock, ed. B. Faybishenko, Geophysical Monograph Series, 162, 33, 2005.

  13. Drainage fracture networks in elastic solids

    NASA Astrophysics Data System (ADS)

    Hafver, Andreas; Kobchenko, Maya; Jettestuen, Espen; Renard, Francois; Galland, Olivier; Mathhiesen, Joachim; Meakin, Paul; Jamtveit, Bjørn; Malthe-Sørenssen, Anders; Dysthe, Dag Kristian

    2013-04-01

    Several geological processes generate large fluid pressures pervasively inside the solid and the fluid is drained out of the solid volume and transported towards the surface by buoyancy. Important examples of this includes dehydrating subducting slabs, hydrocarbon producing kerogen rich shales and partially molten magmas. Such internal production and exsolution of fluids may induce mechanical failure of the solid rock. The resulting fractures provide drainage pathways for the fluid releasing the large fluid pressures. We have performed analogue 2D experiments with uniform gas production in gelatine. We observe fracture patterns that are topologically intermediate between the tree-like structure of river networks and the hierarchical patterns observed in other transport controlled fracture processes, exemplified by cracks in drying mud, hexagonal columnar joints formed in cooling basalts or sequential splitting of igneous rock due to weathering. We propose a simple two-parmeter statistical model that captures the essential features of the gelatine experiments and that is able to produce fracture networks ranging in topology from tree-like to hierarchical. The model is explored and compared with the experiments to gain insight into this class of drainage fracture processes. We also present a discrete element model which is used to investigate the effect of fluid-solid coupling on fracture network topology and fluid expulsion.

  14. Tips and Tricks in Mallet Fracture Fixation.

    PubMed

    Chin, Yuin Cheng; Foo, Tun-Lin

    2016-10-01

    We describe three steps to aid fracture assessment and fixation in the extensor block pin technique for mallet fractures. The first step is the use of fluoroscopy in the initial assessment to determine indication for fixation. Next is the use of supplementary extension block pin to control larger dorsal fragments. The third technique described details the steps of open reduction of nascently malunited fractures. PMID:27595969

  15. Hydraulic fracturing model based on the discrete fracture model and the generalized J integral

    NASA Astrophysics Data System (ADS)

    Liu, Z. Q.; Liu, Z. F.; Wang, X. H.; Zeng, B.

    2016-08-01

    The hydraulic fracturing technique is an effective stimulation for low permeability reservoirs. In fracturing models, one key point is to accurately calculate the flux across the fracture surface and the stress intensity factor. To achieve high precision, the discrete fracture model is recommended to calculate the flux. Using the generalized J integral, the present work obtains an accurate simulation of the stress intensity factor. Based on the above factors, an alternative hydraulic fracturing model is presented. Examples are included to demonstrate the reliability of the proposed model and its ability to model the fracture propagation. Subsequently, the model is used to describe the relationship between the geometry of the fracture and the fracturing equipment parameters. The numerical results indicate that the working pressure and the pump power will significantly influence the fracturing process.

  16. New observations on the ultrastructure of mammalian conducting airway epithelium: application of liquid propane freezing, deep etching, and rotary shadowing techniques to freeze-fracture.

    PubMed

    Carson, J L; Collier, A M; Smith, C A

    1984-10-01

    Freshly isolated, viable hamster tracheal epithelium was rapidly frozen in a jet of liquid nitrogen-cooled propane followed by freeze-fracture, deep etching, and rotary shadowing. Examination of the replicas by transmission electron microscopy revealed characteristic features of both ciliated and nonciliated cells, profiles of tight junctional complexes, and two distinct types of membrane particle complexes. The findings of this study suggest that rapid freezing of viable biological specimens coupled with freeze-fracture, deep etching, and rotary shadowing may provide a useful approach to achieving some additional perspectives of cell structure and function. Since the experimental protocol avoided any use of chemical fixation and processing procedures generally employed in electron microscopy, this study also validates for airway epithelium the details of fine structure observed using more conventional ultrastructural methods. PMID:6544880

  17. Magnetoacoustic waves propagating along a dense slab and Harris current sheet and their wavelet spectra

    SciTech Connect

    Mészárosová, Hana; Karlický, Marian; Jelínek, Petr; Rybák, Ján

    2014-06-10

    Currently, there is a common endeavor to detect magnetoacoustic waves in solar flares. This paper contributes to this topic using an approach of numerical simulations. We studied a spatial and temporal evolution of impulsively generated fast and slow magnetoacoustic waves propagating along the dense slab and Harris current sheet using two-dimensional magnetohydrodynamic numerical models. Wave signals computed in numerical models were used for computations of the temporal and spatial wavelet spectra for their possible comparison with those obtained from observations. It is shown that these wavelet spectra allow us to estimate basic parameters of waveguides and perturbations. It was found that the wavelet spectra of waves in the dense slab and current sheet differ in additional wavelet components that appear in association with the main tadpole structure. These additional components are new details in the wavelet spectrum of the signal. While in the dense slab this additional component is always delayed after the tadpole head, in the current sheet this component always precedes the tadpole head. It could help distinguish a type of the waveguide in observed data. We present a technique based on wavelets that separates wave structures according to their spatial scales. This technique shows not only how to separate the magnetoacoustic waves and waveguide structure in observed data, where the waveguide structure is not known, but also how propagating magnetoacoustic waves would appear in observations with limited spatial resolutions. The possibilities detecting these waves in observed data are mentioned.

  18. A modularized pulse forming line using glass-ceramic slabs.

    PubMed

    Wang, Songsong; Shu, Ting; Yang, Hanwu

    2012-08-01

    In our lab, a kind of glass-ceramic slab has been chosen to study the issues of applying solid-state dielectrics to pulse forming lines (PFLs). Limited by the manufacture of the glass-ceramic bulk with large sizes, a single ceramic slab is hard to store sufficient power for the PFL. Therefore, a modularized PFL design concept is proposed in this paper. We regard a single ceramic slab as a module to form each single Blumlein PFL. We connect ceramic slabs in series to enlarge pulse width, and stack the ceramic Blumlein PFLs in parallel to increase the output voltage amplitude. Testing results of a single Blumlein PFL indicate that one ceramic slab contributes about 11 ns to the total pulse width which has a linear relation to the number of the ceramic slabs. We have developed a prototype facility of the 2-stage stacked Blumlein PFL with a length of 2 ceramic slabs. The PFL is dc charged up to 5 kV, and the output voltage pulse of 10 kV, 22 ns is measured across an 8 Ω load. Simulation and experiment results in good agreement demonstrate that the modularized design is reasonable. PMID:22938320

  19. Impact Resistance Behaviour of Banana Fiber Reinforced Slabs

    NASA Astrophysics Data System (ADS)

    Che Muda, Zakaria; Syamsir, Agusril; Nasharuddin Mustapha, Kamal; Rifdy Samsudin, Muhamad; Thiruchelvam, Sivadass; Usman, Fathoni; Beddu, Salmia; Liyana Mohd Kamal, Nur; Ashraful Alam, Md; Birima, Ahmed H.; Zaroog, O. S.

    2016-03-01

    This paper investigate the performance of banana fibre reinforced slabs 300mm × 300mm size with varied thickness subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.25 kg drop at 1 m height has been used in this research work. The main variables for the study is to find the relationship of the impact resistance against the BF contents and slab thickness. A linear relationship has been established between first and ultimate crack resistance against BF contents and slab thickness by the experiment. The linear relationship has also been established between the service (first) crack and ultimate crack resistance against the BF contents for a constant spacing for various banana fibre reinforced slab thickness. The increment in BF content has more effect on the first crack resistance than the ultimate crack resistance. The linear relationship has also been established between the service (first) crack and ultimate crack resistance against the various slab thickness. Overall 1.5% BF content with slab thickness of 40 mm exhibit better first and ultimate crack resistance up to 16 times and up to 17 times respectively against control slab (without BF)

  20. Seismic constraints on the morphology of deep slabs

    NASA Astrophysics Data System (ADS)

    Fischer, Karen M.; Jordan, Thomas H.; Creager, Kenneth C.

    1988-05-01

    Residual sphere images from deep earthquakes not only detect the presence of slab-associated velocity anomalies but also lend insight into the flow and deformation of lithosphere subducted into the lower mantle. We have compared travel times from deep events in the Kuril and Mariana arcs with the seismic velocity anomalies implied by kinematical models that thicken the slab perpendicular to its plane by reducing the vertical velocity of the flow with depth. We assume that the details of the deformation (whether the slab buckles, imbricates, fragments, etc.) are averaged out along the ray paths, and hence our models constrain the scale, not the mode, of slab thickening. The deep event travel times are best fit by undeformed models, but the ability of the residual sphere method to resolve slab thickness is limited by ray bending effects. Although the Mariana times are consistent with advective thickening factors of 5 or more, factors larger than 3 are ruled out by the Kuril data. For all models examined, the data require that slab material extends to depths of 900-1000 km. Global tomographic models and regional studies which delineate high-velocity anomalies in the lower mantle beneath zones of Cenozoic subduction are consistent with our results, as is recent work on pulse distortion by slab gradients. Comparison of observed and predicted rates of seismic moment release suggests that if substantial advective thickening does occur, it is largely aseismic.

  1. A modularized pulse forming line using glass-ceramic slabs.

    PubMed

    Wang, Songsong; Shu, Ting; Yang, Hanwu

    2012-08-01

    In our lab, a kind of glass-ceramic slab has been chosen to study the issues of applying solid-state dielectrics to pulse forming lines (PFLs). Limited by the manufacture of the glass-ceramic bulk with large sizes, a single ceramic slab is hard to store sufficient power for the PFL. Therefore, a modularized PFL design concept is proposed in this paper. We regard a single ceramic slab as a module to form each single Blumlein PFL. We connect ceramic slabs in series to enlarge pulse width, and stack the ceramic Blumlein PFLs in parallel to increase the output voltage amplitude. Testing results of a single Blumlein PFL indicate that one ceramic slab contributes about 11 ns to the total pulse width which has a linear relation to the number of the ceramic slabs. We have developed a prototype facility of the 2-stage stacked Blumlein PFL with a length of 2 ceramic slabs. The PFL is dc charged up to 5 kV, and the output voltage pulse of 10 kV, 22 ns is measured across an 8 Ω load. Simulation and experiment results in good agreement demonstrate that the modularized design is reasonable.

  2. Nonbridging external fixation of distal radius fractures.

    PubMed

    Eichenbaum, Matthew D; Shin, Eon K

    2010-08-01

    Surgical management of distal radius fractures continues to evolve because of their high incidence in an increasingly active elderly population. Traditional radiocarpal external fixation relies on ligamentotaxis for fracture reduction but has several drawbacks. Nonbridging external fixation has evolved to provide early wrist mobility in the setting of anatomic fracture reduction. Several studies of the nonbridging technique have demonstrated satisfactory results in isolated nonbridging external fixation series and in comparison with traditional spanning external fixation. Nonbridging external fixation for surgical treatment of distal radius fractures can be technically demanding and requires at least 1 cm of intact volar cortex in the distal fracture fragment for successful implementation.

  3. Evaluation and Management of Vertebral Compression Fractures

    PubMed Central

    Alexandru, Daniela; So, William

    2012-01-01

    Compression fractures affect many individuals worldwide. An estimated 1.5 million vertebral compression fractures occur every year in the US. They are common in elderly populations, and 25% of postmenopausal women are affected by a compression fracture during their lifetime. Although these fractures rarely require hospital admission, they have the potential to cause significant disability and morbidity, often causing incapacitating back pain for many months. This review provides information on the pathogenesis and pathophysiology of compression fractures, as well as clinical manifestations and treatment options. Among the available treatment options, kyphoplasty and percutaneous vertebroplasty are two minimally invasive techniques to alleviate pain and correct the sagittal imbalance of the spine. PMID:23251117

  4. Galeazzi fracture.

    PubMed

    Atesok, Kivanc I; Jupiter, Jesse B; Weiss, Arnold-Peter C

    2011-10-01

    Galeazzi fracture is a fracture of the radial diaphysis with disruption at the distal radioulnar joint (DRUJ). Typically, the mechanism of injury is forceful axial loading and torsion of the forearm. Diagnosis is established on radiographic evaluation. Underdiagnosis is common because disruption of the ligamentous restraints of the DRUJ may be overlooked. Nonsurgical management with anatomic reduction and immobilization in a long-arm cast has been successful in children. In adults, nonsurgical treatment typically fails because of deforming forces acting on the distal radius and DRUJ. Open reduction and internal fixation is the preferred surgical option. Anatomic reduction and rigid fixation should be followed by intraoperative assessment of the DRUJ. Further intraoperative interventions are based on the reducibility and postreduction stability of the DRUJ. Misdiagnosis or inadequate management of Galeazzi fracture may result in disabling complications, such as DRUJ instability, malunion, limited forearm range of motion, chronic wrist pain, and osteoarthritis.

  5. Pediatric Thighbone (Femur) Fracture

    MedlinePlus

    ... fractures in infants under 1 year old is child abuse. Child abuse is also a leading cause of thighbone fracture ... contact sports • Being in a motor vehicle accident • Child abuse Types of Femur Fractures (Classification) Femur fractures vary ...

  6. Gravity-Driven Hydraulic Fractures

    NASA Astrophysics Data System (ADS)

    Germanovich, L. N.; Garagash, D.; Murdoch, L. C.; Robinowitz, M.

    2014-12-01

    -dominated head to obtain a complete closed-form solution. We then analyze the gravity fracture propagation in conditions of either continuous injection or finite volume release for sets of parameters representative of dense waste injection technique and low viscosity magma diking.

  7. Use of Cutting-Edge Horizontal and Underbalanced Drilling Technologies and Subsurface Seismic Techniques to Explore, Drill and Produce Reservoired Oil and Gas from the Fractured Monterey Below 10,000 ft in the Santa Maria Basin of California

    SciTech Connect

    George Witter; Robert Knoll; William Rehm; Thomas Williams

    2006-06-30

    This project was undertaken to demonstrate that oil and gas can be drilled and produced safely and economically from a fractured Monterey reservoir in the Santa Maria Basin of California by employing horizontal wellbores and underbalanced drilling technologies. Two vertical wells were previously drilled in this area with heavy mud and conventional completions; neither was commercially productive. A new well was drilled by the project team in 2004 with the objective of accessing an extended length of oil-bearing, high-resistivity Monterey shale via a horizontal wellbore, while implementing managed-pressure drilling (MPD) techniques to avoid formation damage. Initial project meetings were conducted in October 2003. The team confirmed that the demonstration well would be completed open-hole to minimize productivity impairment. Following an overview of the geologic setting and local field experience, critical aspects of the application were identified. At the pre-spud meeting in January 2004, the final well design was confirmed and the well programming/service company requirements assigned. Various design elements were reduced in scope due to significant budgetary constraints. Major alterations to the original plan included: (1) a VSP seismic survey was delayed to a later phase; (2) a new (larger) surface hole would be drilled rather than re-enter an existing well; (3) a 7-in. liner would be placed into the top of the Monterey target as quickly as possible to avoid problems with hole stability; (4) evaluation activities were reduced in scope; (5) geosteering observations for fracture access would be deduced from penetration rate, cuttings description and hydrocarbon in-flow; and (6) rather than use nitrogen, a novel air-injection MPD system was to be implemented. Drilling operations, delayed from the original schedule by capital constraints and lack of rig availability, were conducted from September 12 to November 11, 2004. The vertical and upper curved sections were

  8. Lower mantle seismic scatterers below the subducting Tonga slab: Evidence for slab entrainment of transition zone materials

    NASA Astrophysics Data System (ADS)

    Kaneshima, Satoshi

    2013-09-01

    We show evidence that materials with significantly different elastic properties are juxtaposed in the lower mantle immediately below the subducting Tonga slab (depths ⩽1000 km), like the anomalies preferentially located beneath the lower mantle slabs at other Pacific subduction zones (Kaneshima, 2009). Array analyses of wave form data of short period seismic networks at western United States and Japan for deep earthquakes at the Tonga slab reveal S-to-P scatterers with a size less than the wavelengths (˜10 km). The scatterers are located mostly outside of the slab by several tens of kilometers. Assuming a locally planar interface for the geometry of the scatterers, the amplitudes and polarities of the S-to-P waves are modeled to constrain the properties of the scatterers. We find that the scatterers are steeply dipping, the Vs increases oceanward across the interface, and the Vs contrasts are at least comparable to that associated with the post-spinel transformation (⩾6%). It is unclear at this stage what these subslab scatterers represent, so we discuss about three mechanisms which seem plausible from mantle dynamics viewpoints: (1) they may represent basaltic rocks which were emplaced by partial melting immediately beneath the former oceanic lithosphere-asthenosphere boundary (LAB) before the slab started subducting; (2) alternatively the elastic anomalies of the scatterers may be caused by localized presence of dehydrated water; or (3) the scatterers may correspond to a sharp boundary between fine-grained isotropic rocks in the immediate vicinity of the slab and coarse grained anisotropic rocks more distant from the slab. The presence of pronounced and localized elastic anomalies preferentially beneath the slabs in the shallow lower mantle, whatever its mechanism is, implies that a geophysically observable amount of transition zone material is entrained by the subducting slabs into the lower mantle.

  9. The feeder system of the Toba supervolcano from the slab to the shallow reservoir.

    PubMed

    Koulakov, Ivan; Kasatkina, Ekaterina; Shapiro, Nikolai M; Jaupart, Claude; Vasilevsky, Alexander; El Khrepy, Sami; Al-Arifi, Nassir; Smirnov, Sergey

    2016-01-01

    The Toba Caldera has been the site of several large explosive eruptions in the recent geological past, including the world's largest Pleistocene eruption 74,000 years ago. The major cause of this particular behaviour may be the subduction of the fluid-rich Investigator Fracture Zone directly beneath the continental crust of Sumatra and possible tear of the slab. Here we show a new seismic tomography model, which clearly reveals a complex multilevel plumbing system beneath Toba. Large amounts of volatiles originate in the subducting slab at a depth of ∼150 km, migrate upward and cause active melting in the mantle wedge. The volatile-rich basic magmas accumulate at the base of the crust in a ∼50,000 km(3) reservoir. The overheated volatiles continue ascending through the crust and cause melting of the upper crust rocks. This leads to the formation of a shallow crustal reservoir that is directly responsible for the supereruptions. PMID:27433784

  10. The feeder system of the Toba supervolcano from the slab to the shallow reservoir

    PubMed Central

    Koulakov, Ivan; Kasatkina, Ekaterina; Shapiro, Nikolai M.; Jaupart, Claude; Vasilevsky, Alexander; El Khrepy, Sami; Al-Arifi, Nassir; Smirnov, Sergey

    2016-01-01

    The Toba Caldera has been the site of several large explosive eruptions in the recent geological past, including the world's largest Pleistocene eruption 74,000 years ago. The major cause of this particular behaviour may be the subduction of the fluid-rich Investigator Fracture Zone directly beneath the continental crust of Sumatra and possible tear of the slab. Here we show a new seismic tomography model, which clearly reveals a complex multilevel plumbing system beneath Toba. Large amounts of volatiles originate in the subducting slab at a depth of ∼150 km, migrate upward and cause active melting in the mantle wedge. The volatile-rich basic magmas accumulate at the base of the crust in a ∼50,000 km3 reservoir. The overheated volatiles continue ascending through the crust and cause melting of the upper crust rocks. This leads to the formation of a shallow crustal reservoir that is directly responsible for the supereruptions. PMID:27433784

  11. Clogging of fractured formations by biocolloids suspended in reclaimed wastewater

    NASA Astrophysics Data System (ADS)

    Chrysikopoulos, C.; Masciopinto, C.; La Mantia, R.; Manariotis, I. D.

    2009-12-01

    Two pilot-scale fractured filters consisting of horizontal limestone slabs were employed to investigate fracture aperture clogging due to deposition of biocolloids suspended in reclaimed wastewater. To better understand the behavior of real fractured aquifers, the filters intentionally were not “clean”. The fracture apertures were randomly spread with soil deposits and both filters were pre-flooded with reclaimed wastewater to simulate the field conditions of the Nardò fractured aquifer in the Salento area, Italy, where due to artificial groundwater recharge the fractures are not “clean”. One of the filters was injected with secondary effluent from a wastewater treatment plant collected prior to the chlorination step, and the other with exactly the same effluent, which was further treated in a commercial membrane reactor. Consequently, the organic and pathogen concentrations were considerably higher in the secondary effluent than the membrane reactor effluent. The injected wastewater was continuously recirculated. The pathogen removal by the filter was more significant for the secondary wastewater than the cleaner membrane reactor effluent. A simple mathematical model was developed to describe fracture clogging. The results suggest that the hydraulic conductivity of fractured filters can be significantly reduced from the retention of viable and inactivated biocolloids originating from reclaimed wastewater. Fracture aperture clogging is strongly related to the chemical oxygen demand of the reclaimed wastewater injected. Schematic diagram of the experimental setup.

  12. Phase Field Fracture Mechanics.

    SciTech Connect

    Robertson, Brett Anthony

    2015-11-01

    For this assignment, a newer technique of fracture mechanics using a phase field approach, will be examined and compared with experimental data for a bend test and a tension test. The software being used is Sierra Solid Mechanics, an implicit/explicit finite element code developed at Sandia National Labs in Albuquerque, New Mexico. The bend test experimental data was also obtained at Sandia Labs while the tension test data was found in a report online from Purdue University.

  13. Transition Zone Anisotropy Beneath Deep Slabs and the Transport of Water into the Lower Mantle

    NASA Astrophysics Data System (ADS)

    Nowacki, A.; Kendall, J. M.; Wookey, J. M.; Pemberton, A.

    2014-12-01

    To first order, the Earth exhibits seismic anisotropy (the variation of wave speed with direction) only in the uppermost and lowermost mantle, as well as the inner core. However, a growing body of evidence suggests that it is also present in the transition zone (TZ) and uppermost lower mantle (LM). We use the method of 'source-side' shear wave splitting to observe anisotropy in the regions of deep earthquakes distributed globally. This technique removes the effects of anisotropy near well-characterised receiver stations to infer the splitting at the source, allowing us to probe the midmantle where slabs appear to be impinging on the LM. Over 130 observations, mainly beneath South America, Tonga and Japan, are made for earthquakes 200-650 km deep. They show shear wave splitting with mean delay time 1.0 s, but there is no trend of decreasing—or increasing—δt with depth. Because of the distribution of circum-Pacific deep earthquakes, our data are only sensitive to anisotropy in the sub-slab region and the slab itself. Our observations reveal a consistent pattern: the data are best fit with a style of anisotropy which has a rotational symmetry axis pointing upwards along the slab. This pattern of anisotropy is typical of approximately uniaxial flattening of material which develops a lattice preferred orientation (LPO) by dislocation creep. This is consistent with the expected mechanics of slab sinking and supported by the P-axes of moment tensor solutions for the events we analyse. Because the amount of anisotropy does not appear to be related to the depth, we can confine the source region to either the slab itself, or the top of the LM. The amount of anisotropy makes it unlikely that MgSiO3-perovskite in the LM is the source, as it would require a high-strain layer over 1500~km thick. Dense hydrous magnesium silicate (DHMS) phases which are known to become stable at the base of the TZ (the so-called 'alphabet' phases; such as D and superhydrous B), do however

  14. High-resolution Waveform Tomography of Mantle Transition Zone and Slab Structure beneath Northeast China

    NASA Astrophysics Data System (ADS)

    TAO, K.; Grand, S.; Niu, F.; Chen, M.; Zhu, H.

    2015-12-01

    Northeast China has undergone widespread extension and magmatism since Late Cretaceous. There are many Cenozoic volcanoes in this region and a few of them are still active today, such as Changbaishan and Wudalianchi. Previous tomography models show stagnant slabs within the transition zone beneath NE China, and suggest deep slab control on the regional tectonics and volcanism. Proposed mechanisms for the magmatism include: 1) a mantle plume, 2) hot upwelling above the stagnant slab by deep dehydration and 3) upwelling induced by deep slab segmentation and detachment. To date, NE China seismic images still contain enough uncertainty to allow for multiple models. Using the dense seismic data coverage in NE China and adjacent regions our goal is to make high-resolution image of the transition zone and slab structure to test the origins of intraplate volcanism. Recently Chen et al. (2015) developed a 3D model for P and S velocity structure beneath East Asia using adjoint tomography using the SPECFEM3D synthetic technique and cross-correlation time shifts as the objective function. We use their model as a starting model and further improve the resolution by fitting waveforms to a shorter period (from ~12s to ~5s) using the correlation coefficient as the objective function. The new objective function is closely related to the L2 waveform misfit but is insensitive to a constant amplitude ratio between the synthetic and data within each time window used. This feature is desirable because the absolute amplitude can be hard to model as it can be affected by many factors difficult to incorporate in simulations, such as site effects, source magnitude and mechanism error or even poor calibration of instruments. During inversion we focus specifically on the transition zone and the structure of slabs with the goal of fitting triplicated and multipath body waves. We have performed a waveform inversion experiment using data from a single deep earthquake. Excellent fits of the

  15. Development of common conversion point stacking of receiver functions for detecting subducted slabs

    NASA Astrophysics Data System (ADS)

    Abe, Y.; Ohkura, T.; Hirahara, K.; Shibutani, T.

    2010-12-01

    In subduction zones, the subducting slabs are thought to convey fluid into the mantle wedge to cause arc volcanism (Hasegawa et al., 2008. Iwamori, 2007). Kawakatsu & Watada (2007) examined the Pacific slab subducting beneath northeast Japan with receiver function (RF) analysis, and revealed where the hydrated oceanic crust and the serpentinized mantle wedge exist. In the other subduction zones, it is also essential to examine subducting slabs for better understanding of water transportation and volcanic activities. In this study, we develop a new method to migrate RFs in order to examine subducting slabs with high dip angle (Abe et al., submitted to GJI) and apply this method to examination of the Philippine Sea slab (PHS). The RF technique is one of the useful methods to obtain seismic velocity discontinuities. Ps phases converted at discontinuities in a teleseismic coda can be detected by RF analysis. RFs are usually converted to depth domain assuming a 1-d velocity structure, and the geometry of discontinuities is obtained (e.g. Yamauchi et al., 2003). In subduction zones, however, subducting slabs usually dip, and we should take into account the refraction of seismic waves at dipping interfaces. Therefore, we use the multi-stage fast marching method (FMM, de Kool et al., 2006) to convert RFs into depth domain. We stack transverse RFs, since polarity of them does not change depending on their dip angles and they are better at detecting phases converted at dipping interfaces than radial RFs. We have confirmed that this method works properly with synthetic test. We apply our method to waveform data observed in Kyushu, Japan, where PHS is subducting toward WNW and the Wadati-Benioff zone dips at 30° at depths up to 80 km, and dips at 70° at depths between 80 km and 170 km. We obtain a vertical section, on which RF amplitude is projected, across central part of Kyushu perpendicular to the depth contour of the Wadati-Benioff zone. On the section, positive peaks of

  16. Hybrid Heat Capacity - Moving Slab Laser Concept

    SciTech Connect

    Stappaerts, E A

    2002-04-01

    A hybrid configuration of a heat capacity laser (HCL) and a moving slab laser (MSL) has been studied. Multiple volumes of solid-state laser material are sequentially diode-pumped and their energy extracted. When a volume reaches a maximum temperature after a ''sub-magazine depth'', it is moved out of the pumping region into a cooling region, and a new volume is introduced. The total magazine depth equals the submagazine depth times the number of volumes. The design parameters are chosen to provide high duty factor operation, resulting in effective use of the diode arrays. The concept significantly reduces diode array cost over conventional heat capacity lasers, and it is considered enabling for many potential applications. A conceptual design study of the hybrid configuration has been carried out. Three concepts were evaluated using CAD tools. The concepts are described and their relative merits discussed. Because of reduced disk size and diode cost, the hybrid concept may allow scaling to average powers on the order of 0.5 MW/module.

  17. Rotational flow in tapered slab rocket motors

    NASA Astrophysics Data System (ADS)

    Saad, Tony; Sams, Oliver C.; Majdalani, Joseph

    2006-10-01

    Internal flow modeling is a requisite for obtaining critical parameters in the design and fabrication of modern solid rocket motors. In this work, the analytical formulation of internal flows particular to motors with tapered sidewalls is pursued. The analysis employs the vorticity-streamfunction approach to treat this problem assuming steady, incompressible, inviscid, and nonreactive flow conditions. The resulting solution is rotational following the analyses presented by Culick for a cylindrical motor. In an extension to Culick's work, Clayton has recently managed to incorporate the effect of tapered walls. Here, an approach similar to that of Clayton is applied to a slab motor in which the chamber is modeled as a rectangular channel with tapered sidewalls. The solutions are shown to be reducible, at leading order, to Taylor's inviscid profile in a porous channel. The analysis also captures the generation of vorticity at the surface of the propellant and its transport along the streamlines. It is from the axial pressure gradient that the proper form of the vorticity is ascertained. Regular perturbations are then used to solve the vorticity equation that prescribes the mean flow motion. Subsequently, numerical simulations via a finite volume solver are carried out to gain further confidence in the analytical approximations. In illustrating the effects of the taper on flow conditions, comparisons of total pressure and velocity profiles in tapered and nontapered chambers are entertained. Finally, a comparison with the axisymmetric flow analog is presented.

  18. Locking plates in proximal humerus fractures.

    PubMed

    Strohm, P C; Helwig, P; Konrad, G; Südkamp, N P

    2007-12-01

    It is well known that proximal humerus fractures are among the three most frequent fracture types. Epidemiological invetsigations show that in people elder than 60 years the fracture of the proximal humerus is more frequent than fractures of the hip region (17). Over the last decades several techniques have been applied for treatment of proximal humerus fractures. Widely accepted is the initiation of a conservative treatment regimen for undisplaced fractures, however, the standard treatment for displaced fractures, especially three and four part fractures, is still the center of scientific debate. Many different implants have been tested and investigated, thus demonstrating lack of sufficient results. Over the last years the development of angle stable, locking implants started and clinical studies demonstrated encouraging results. In our clinic the locking proximal humerus plate and the PHILOS plate advanced to the implant of choice for treatment of displaced proximal humerus fractures. There are still cases of implant failure and humerus head necrosis, but most of these complications were caused by the fracture type and not an implant specific problem. However the overall results with these new implants are encouraging. Key words: locking plates, proximal humerus fracture, humerus, humerus fracture, PHILOS, PHP.

  19. 23. Surrender interview site, showing Pemberton Avenue concrete slab road ...

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

    23. Surrender interview site, showing Pemberton Avenue concrete slab road type with gutter (asphalt construction typical on Union and Confederate Avenues), view to the sw. - Vicksburg National Military Park Roads & Bridges, Vicksburg, Warren County, MS

  20. 2. FLAME DEFLECTOR FROM THE REINFORCED CONCRETE SLAB ROOF, VIEW ...

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

    2. FLAME DEFLECTOR FROM THE REINFORCED CONCRETE SLAB ROOF, VIEW TOWARDS SOUTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-2, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  1. 9. FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, VIEW TOWARDS ...

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

    9. FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, VIEW TOWARDS NORTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  2. Segmented Hellenic slab rollback driving Aegean deformation and seismicity

    NASA Astrophysics Data System (ADS)

    Sachpazi, M.; Laigle, M.; Charalampakis, M.; Diaz, J.; Kissling, E.; Gesret, A.; Becel, A.; Flueh, E.; Miles, P.; Hirn, A.

    2016-01-01

    The NE dipping slab of the Hellenic subduction is imaged in unprecedented detail using teleseismic receiver function analysis on a dense 2-D seismic array. Mapping of slab geometry for over 300 km along strike and down to 100 km depth reveals a segmentation into dipping panels by along-dip faults. Resolved intermediate-depth seismicity commonly attributed to dehydration embrittlement is shown to be clustered along these faults. Large earthquakes occurrence within the upper and lower plate and at the interplate megathrust boundary show a striking correlation with the slab faults suggesting high mechanical coupling between the two plates. Our results imply that the general slab rollback occurs here in a differential piecewise manner imposing its specific stress and deformation pattern onto the overriding Aegean plate.

  3. DETAIL OF NORTH GUARDRAIL AND EXPANSION JOINT IN CONCRETE SLAB, ...

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

    DETAIL OF NORTH GUARDRAIL AND EXPANSION JOINT IN CONCRETE SLAB, SHOWING DAMAGED SECTION OF GUARDRAIL AND ALUMINUM REPLACEMENT. VIEW TO NORTHWEST. - Hassayampa Bridge, Spanning Hassayampa River at old U.S. Highway 80, Arlington, Maricopa County, AZ

  4. Radiative Transfer Model for Translucent Slab Ice on Mars

    NASA Astrophysics Data System (ADS)

    Andrieu, F.; Schmidt, F.; Douté, S.; Schmitt, B.; Brissaud, O.

    2016-09-01

    We developed a radiative transfer model that simulates in VIS/NIR the bidirectional reflectance of a contaminated slab layer of ice overlaying a granular medium, under geometrical optics conditions to study martian ices.

  5. Waveform effects of a metastable olivine tongue in subducting slabs

    NASA Technical Reports Server (NTRS)

    Vidale, John E.; Williams, Quentin; Houston, Heidi

    1991-01-01

    Velocity models of subducting slabs with a kinetically-depressed olivine to beta- and gamma-spinel transition are constructed, and the effect that such structures would have on teleseismic P waveforms are examined using a full-wave finite-difference method. These 2D calculations yielded waveforms at a range of distances in the downdip direction. The slab models included a wedge-shaped, low-velocity metastable olivine tongue (MOTO) to a depth of 670 km, as well as a plausible thermal anomaly; one model further included a 10-km-thick fast layer on the surface of the slab. The principal effect of MOTO is to produce grazing reflections at wide angles off the phase boundary, generating a secondary arrival 0 to 4 seconds after the initial arrival depending on the take-off angle. The amplitude and timing of this feature vary with the lateral location of the seismic source within the slab cross-section.

  6. Benchmark study for total enery electrons in thick slabs

    NASA Technical Reports Server (NTRS)

    Jun, I.

    2002-01-01

    The total energy deposition profiles when highenergy electrons impinge on a thick slab of elemental aluminum, copper, and tungsten have been computed using representative Monte Carlo codes (NOVICE, TIGER, MCNP), and compared in this paper.

  7. Analytical and Numerical Solution for a Solidifying Liquid Alloy Slab

    NASA Technical Reports Server (NTRS)

    Antar, B. N.

    1983-01-01

    Numerical and analytical solutions are presented for the temperature and concentration distributions during the solidification of a binary liquid alloy slab. The slab is taken to be of a finite depth but infinite in the horizontal direction. The solidification process is started by withdrawing a fixed amount of heat from the lower surface of the slab. The upper surface of the slab is subjected to both radiation and convective conditions. The solution gives the concentration and temperature profiles and the interface position as a function of time. Due to the smallness of the mass diffusion coefficient in the solid, the numerical solution method breaks down whenever the ratio of the diffusivities in the solid and the liquid falls below a certain value. An analytical method is developed which gives accurate solution for any value of the diffusivity ratio.

  8. 7. REINFORCED CONCRETE SLAB ROOF FROM NORTHWEST EDGE, FLAME DEFLECTOR ...

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

    7. REINFORCED CONCRETE SLAB ROOF FROM NORTHWEST EDGE, FLAME DEFLECTOR AT RIGHT, VIEW TOWARDS SOUTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, CaptiveTest Stand D-3, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  9. 11. REINFORCED CONCRETE SLAB ROOF, FLAME DEFLECTOR AT RIGHT, CONTROL ...

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

    11. REINFORCED CONCRETE SLAB ROOF, FLAME DEFLECTOR AT RIGHT, CONTROL BUILDING B AT FAR CENTER RIGHT. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-4, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  10. 9. STONE SLAB CULVERT UNDER CARRIAGE ROAD AT HORSESHOE CURVE ...

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

    9. STONE SLAB CULVERT UNDER CARRIAGE ROAD AT HORSESHOE CURVE NEAR GIANT SLIDE TRAIL MARKER ON AROUND-THE-MOUNTAIN LOOP. - Rockefeller Carriage Roads, Mount Desert Island, Bar Harbor, Hancock County, ME

  11. Interior view of groundfloor porch showing exposed concrete floor slab ...

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

    Interior view of ground-floor porch showing exposed concrete floor slab system, facing west. - Albrook Air Force Station, Field Officer's Quarters, West side of Dargue Avenue Circle, Balboa, Former Panama Canal Zone, CZ

  12. OVERVIEW LOOKING SOUTH OF CONTAINMENT SYSTEM (TOP), SLAB CASTING MACHINE ...

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

    OVERVIEW LOOKING SOUTH OF CONTAINMENT SYSTEM (TOP), SLAB CASTING MACHINE AND RUN OUT WITH TRAVELING TORCH. MACHINE IS CASTING IN TWIN MOLD. - U.S. Steel, Fairfield Works, Continuous Caster, Fairfield, Jefferson County, AL

  13. 31. VIEW OF CONCRETE SLAB AT WEST ENTRANCE OF WALKWAY. ...

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

    31. VIEW OF CONCRETE SLAB AT WEST ENTRANCE OF WALKWAY. '1944 JOE LANDETA' SCRATCHED INTO FRESH CONCRETE. March 1987 - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  14. 27. VAL, DETAIL OF LAUNCHER SLAB AND LAUNCHER RAIL WITH ...

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

    27. VAL, DETAIL OF LAUNCHER SLAB AND LAUNCHER RAIL WITH 7 INCH DIAMETER HOLE FOR SUPPORT CARRIAGE LOCKING PIN. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  15. 34. VAL, DETAIL OF STAIRS ON COUNTERWEIGHT SLAB WITH COUNTERWEIGHT ...

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

    34. VAL, DETAIL OF STAIRS ON COUNTERWEIGHT SLAB WITH COUNTERWEIGHT CAR RAILS ON RIGHT AND PERSONNEL CAR RAILS ON LEFT. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  16. 5. VAL LAUNCHER BRIDGE OVER LAUNCHER SLAB TAKEN FROM RESERVOIR ...

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

    5. VAL LAUNCHER BRIDGE OVER LAUNCHER SLAB TAKEN FROM RESERVOIR LOOKING NORTH. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  17. 49. DETAIL VIEW OF SLOPE PREPARATION FOR VARIABLEANGLE LAUNCHER SLAB ...

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

    49. DETAIL VIEW OF SLOPE PREPARATION FOR VARIABLE-ANGLE LAUNCHER SLAB LOOKING NORTH, November 6, 1946. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  18. 8. VAL COUNTERWEIGHT CAR ON COUNTERWEIGHT SLAB AND CAMERA TOWER ...

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

    8. VAL COUNTERWEIGHT CAR ON COUNTERWEIGHT SLAB AND CAMERA TOWER TAKEN FROM RESERVOIR LOOKING SOUTHWEST. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  19. Casimir effect for two lossy dispersive dielectric slabs

    NASA Astrophysics Data System (ADS)

    Matloob, R.; Keshavarz, A.; Sedighi, D.

    1999-11-01

    The electromagnetic field is quantized using the Green's-function method for the geometry of a Fabry-Perot cavity, made up of two identical lossy dispersive slabs of finite thickness. The dielectric functions of the slabs are assumed to be an arbitrary complex function of frequency obeying causality requirements. The attractive Casimir force between the two slabs is calculated by the help of the latter field operators, via evaluating the difference between the vacuum pressures on both sides of each slab. Special attention is paid to the limiting case of the Casimir effect for two conducting plates. The Lorentz model of the dielectric function is used to demonstrate the variation of the force in terms of plasma frequency. The Casimir force expression is also related to the imaginary part of the response function. The latter expression is used to introduce the repulsive Casimir force between two conducting plates located inside a Fabry-Perot cavity.

  20. High frequency seismic waves and slab structures beneath Italy

    NASA Astrophysics Data System (ADS)

    Sun, Daoyuan; Miller, Meghan S.; Piana Agostinetti, Nicola; Asimow, Paul D.; Li, Dunzhu

    2014-04-01

    Tomographic images indicate a complicated subducted slab structure beneath the central Mediterranean where gaps in fast velocity anomalies in the upper mantle are interpreted as slab tears. The detailed shape and location of these tears are important for kinematic reconstructions and understanding the evolution of the subduction system. However, tomographic images, which are produced by smoothed, damped inversions, will underestimate the sharpness of the structures. Here, we use the records from the Italian National Seismic Network (IV) to study the detailed slab structure. The waveform records for stations in Calabria show large amplitude, high frequency (f>5 Hz) late arrivals with long coda after a relatively low-frequency onset for both P and S waves. In contrast, the stations in the southern and central Apennines lack such high frequency arrivals, which correlate spatially with the central Apennines slab window inferred from tomography and receiver function studies. Thus, studying the high frequency arrivals provides an effective way to investigate the structure of slab and detect possible slab tears. The observed high frequency arrivals in the southern Italy are the strongest for events from 300 km depth and greater whose hypocenters are located within the slab inferred from fast P-wave velocity perturbations. This characteristic behavior agrees with previous studies from other tectonic regions, suggesting the high frequency energy is generated by small scale heterogeneities within the slab which act as scatterers. Furthermore, using a 2-D finite difference (FD) code, we calculate synthetic seismograms to search for the scale, shape and velocity perturbations of the heterogeneities that may explain features observed in the data. Our preferred model of the slab heterogeneities beneath the Tyrrhenian Sea has laminar structure parallel to the slab dip and can be described by a von Kármán function with a down-dip correlation length of 10 km and 0.5 km in

  1. The fundamental constants of orthotropic affine plate/slab equations

    NASA Technical Reports Server (NTRS)

    Brunelle, E. J.

    1984-01-01

    The global constants associated with orthotropic slab/plate equations are discussed, and the rotational behavior of the modulus/compliance components associated with orthotropic slabs/plates are addressed. It is concluded that one cluster constant is less than or equal to unity for all physically possible materials. Rotationally anomalous behavior is found in two materials, and a simple inequality which can be used to identify regular or anomalous behavior is presented and discussed in detail.

  2. Arcuate Fractures

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    In the upper left corner of this VIS image are a series of fractures. Where the fractures are exposed on the surface it is impossible to tell the plane of the fracture; however where the fractures are visible in the cliff wall it is possible to see that the fractures dip to the north. This image shows part of the caldera of Tharsis Tholus.

    Image information: VIS instrument. Latitude 1.7, Longitude 176.5 East (183.5 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  3. On Using the Weighted Slab Approximation in Studying the Problem of Cosmic-Ray Transport

    NASA Astrophysics Data System (ADS)

    Ptuskin, Vladimir S.; Jones, Frank C.; Ormes, Jonathan F.

    1996-07-01

    The weighted slab approximation has been used for many years as an approximation to the solution of the full equation for the interstellar propagation of cosmic-ray nuclei. The method has the advantage that the full propagation equation is separated into two independent equations, one for the nuclear physics, the slab model, and one for the astrophysics, the path length distribution or weights. This method is exact (at least for particles with the same charge to mass ratio) in the extreme relativistic regime where energy loss can be neglected but is known to be inaccurate when energy loss is not negligible. In this paper we describe an approach to extending the utility of this technique into regimes where energy change cannot be neglected. Using this method we can show that for the "leaky box" model or models employing diffusion with no convection the weighted slab approximation can give exact solutions only if the escape time or diffusive mean free path is a separable function of position and energy per nucleon (or rigidity).

  4. Delineation of the fractured-rock and unconsolidated overburden ground-water flow systems on the southern part of Manhattan, New York, through use of advanced borehole-geophysical techniques

    NASA Astrophysics Data System (ADS)

    Stumm, Frederick

    2005-11-01

    Advanced borehole-geophysical techniques were used to assess the geohydrology of crystalline bedrock in 31 of 64 boreholes on the southern part of Manhattan Island, N.Y. Ten wells were screened in the unconsolidated overburden (glacial aquifer) to determine water-table elevation, transmissivity, and chloride concentration. The borehole-logging techniques included natural gamma, single-point resistance, short-normal resistivity, mechanical and acoustic caliper, magnetic susceptibility, borehole-fluid temperature and resistivity, borehole-fluid specific conductance, dissolved oxygen, pH, redox, heat-pulse flowmeter (at selected boreholes), borehole deviation, acoustic and optical televiewer, and borehole radar (at selected boreholes). The boreholes penetrated gneiss, schist, and other crystalline bedrock that has an overall southwest to northwest-dipping foliation. Most of the fractures penetrated are nearly horizontal or have moderate- to high-angle northwest or eastward dip azimuths. Heat-pulse flowmeter logs obtained under pumping and nonpumping (ambient) conditions, together with other geophysical logs, indicate transmissive fracture zones in each borehole. The 60-megahertz directional borehole-radar logs delineated the location and orientation of several radar reflectors that did not intersect the projection of the borehole. Fifty-three faults had mean orientation populations of N12°W, 66°W or N11°W, 70°E. Seventy-seven transmissive fractures delineated using the heat-pulse flowmeter had mean orientations of N11°E, 14°SE (majority) and N23°E, 57°NW (minority). The first potentiometric-surface and water-table maps were completed for southern Manhattan of the bedrock and glacial aquifer, respectively. Bedrock transmissivity ranged from 0.7 to 871 feet squared per day. Glacial aquifer transmissivity ranged from 2 to 93,000 feet squared per day. Chloride concentrations ranged from 25 to 17,800 milligrams per liter in the bedrock, and 28 to 15,250 milligrams

  5. Severe thalassaemia intermedia with multiple fractures: role of transfusion therapy.

    PubMed

    Ahmad, Saqib Qayyum; Iqbal, Mudassar; Wahla, Madiha Saeed; Tarrar, Aimel Munir

    2011-11-01

    Thalassaemia intermedia includes thalassaemias with clinical severity intermediate between asymptomatic thalassaemia minor and transfusion dependent thalassaemia major. By definition patients of thalassaemia intermedia maintain a haemoglobin level of 7-10 g/dl and do not, or only occasionally, require blood transfusion. An eight-year-old girl who was a known case of thalassaemia intermedia and had been occasionally transfused presented with fever, pain and swelling over the wrists, ankles and above the right knee joint. Radiographs showed medullary widening, cortical thinning and; multiple, recent and old, partially healed fractures of metadiaphseal regions of long bones. Her fractures have been immobilized by means of back slabs. In view of her recurrent fractures and growth retardation we advised a regular transfusion-chelation regimen to our patient to suppress her ineffective dyserythropoiesis. The treatment is expected to prevent further bone fragility and fractures, as well as improve her life quality. PMID:22125999

  6. Characterizing Seismic Anisotropy across the Peruvian Flat-Slab Subduction Zone: Implications for the Dynamics of Flat-Slabs

    NASA Astrophysics Data System (ADS)

    Eakin, Caroline; Long, Maureen; Beck, Susan; Wagner, Lara; Tavera, Hernando

    2014-05-01

    Although 10% of subduction zones worldwide today exhibit shallow or flat subduction, we are yet to fully understand how and why these slabs go flat. An excellent study location for such a problem is in Peru, where the largest region of flat-subduction currently exists, extending ~1500 km in length (from 3 °S to 15 °S) and ~300 km in width. Across this region we investigate the pattern of seismic anisotropy, an indicator for past and/or ongoing deformation in the upper mantle. To achieve this we conduct shear wave splitting analyzes at 40 broadband stations from the PULSE project (PerU Lithosphere and Slab Experiment). These stations were deployed for 2+ years across the southern half of the Peruvian flat-slab region. We present detailed shear wave splitting results for both teleseismic events (such as SKS, SKKS, PKS, sSKS) that sample the upper mantle column beneath the stations as well as direct S from local events that constrain anisotropy in the upper portion of the subduction zone. We analyze the variability of our results with respect to initial polarizations, ray paths, and frequency content as well as spatial variability between stations as the underlying slab morphology changes. Teleseismic results show predominately NW-SE fast polarizations (trench oblique to sub-parallel) over the flat-slab region east of Lima. These results are consistent with observations of more complex multi-layered anisotropy beneath a nearby permanent station (NNA) that suggests a trench-perpendicular fast direction in the lowest layer in the sub-slab mantle. Further south, towards the transition to steeper subduction, the splitting pattern becomes increasingly dominated by null measurements. Over to the east however, beyond Cuzco, where the mantle wedge might begin to play a role, we record fast polarizations quasi-parallel to the local slab contours. Local S results indicate the presence of weak (delay times typically less than 0.5 seconds) and heterogeneous supra-slab

  7. Scaling of Electron Thermal Conductivity during the Transition between Slab and Mixed Slab-Toroidal ETG Mode

    NASA Astrophysics Data System (ADS)

    Sokolov, Vladimir; Balbaky, Abed; Sen, Amiya K.

    2015-11-01

    Transition from the slab to the toroidal branch of the electron temperature gradient (ETG) mode has been successfully achieved in a basic experiment in Columbia Linear Machine CLM. We found a modest increase in saturated ETG potential fluctuations (~ 2 ×) and a substantial increase in the power density of individual mode peaks (~ 4 - 5 ×) with increased levels of curvature. We have obtained a set of experimental scalings for electron thermal conductivity χ⊥e as a function of the inverse radius of curvature Rc-1 for different fluctuation levels of the initial slab ETG mode. We found that thermal conductivity for pure slab modes is larger than it is for mixed slab-toroidal ETG modes with the same level of mode fluctuation. This effective reduction in diffusive transport can be partly explained by the flute nature of the toroidal ETG mode. This research was supported by the Department of Electrical Engineering of Columbia University.

  8. Use of Cutting-Edge Horizontal and Underbalanced Drilling Technologies and Subsurface Seismic Techniques to Explore, Drill and Produce Reservoired Oil and Gas from the Fractured Monterey Below 10,000 ft in the Santa Maria Basin of California

    SciTech Connect

    George Witter; Robert Knoll; William Rehm; Thomas Williams

    2005-09-29

    This project was undertaken to demonstrate that oil and gas can be drilled and produced safely and economically from a fractured Monterey reservoir in the Santa Maria Basin of California by employing horizontal wellbores and underbalanced drilling technologies. Two vertical wells were previously drilled in this area with heavy mud and conventional completions; neither was commercially productive. A new well was drilled by the project team in 2004 with the objective of accessing an extended length of oil-bearing, high-resistivity Monterey shale via a horizontal wellbore, while implementing managed-pressure drilling (MPD) techniques to avoid formation damage. Initial project meetings were conducted in October 2003. The team confirmed that the demonstration well would be completed open-hole to minimize productivity impairment. Following an overview of the geologic setting and local field experience, critical aspects of the application were identified. At the pre-spud meeting in January 2004, the final well design was confirmed and the well programming/service company requirements assigned. Various design elements were reduced in scope due to significant budgetary constraints. Major alterations to the original plan included: (1) a VSP seismic survey was delayed to a later phase; (2) a new (larger) surface hole would be drilled rather than re-enter an existing well; (3) a 7-in. liner would be placed into the top of the Monterey target as quickly as possible to avoid problems with hole stability; (4) evaluation activities were reduced in scope; (5) geosteering observations for fracture access would be deduced from penetration rate, cuttings description and hydrocarbon in-flow; and (6) rather than use nitrogen, a novel air-injection MPD system was to be implemented. Drilling operations, delayed from the original schedule by capital constraints and lack of rig availability, were conducted from September 12 to November 11, 2004. The vertical and upper curved sections were

  9. USE OF CUTTING-EDGE HORIZONTAL AND UNDERBALANCED DRILLING TECHNOLOGIES AND SUBSURFACE SEISMIC TECHNIQUES TO EXPLORE, DRILL AND PRODUCE RESERVOIRED OIL AND GAS FROM THE FRACTURED MONTEREY BELOW 10,000 FT IN THE SANTA MARIA BASIN OF CALIFORNIA

    SciTech Connect

    George Witter; Robert Knoll; William Rehm; Thomas Williams

    2005-02-01

    This project was undertaken to demonstrate that oil and gas can be drilled and produced safely and economically from a fractured Monterey reservoir in the Santa Maria Basin of California by employing horizontal wellbores and underbalanced drilling technologies. Two vertical wells were previously drilled in this area by Temblor Petroleum with heavy mud and conventional completions; neither was commercially productive. A new well was drilled by the project team in 2004 with the objective of accessing an extended length of oil-bearing, high-resistivity Monterey shale via a horizontal wellbore, while implementing managed-pressure drilling (MPD) techniques to avoid formation damage. Initial project meetings were conducted in October 2003. The team confirmed that the demonstration well would be completed open-hole to minimize productivity impairment. Following an overview of the geologic setting and local field experience, critical aspects of the application were identified. At the pre-spud meeting in January 2004, the final well design was confirmed and the well programming/service company requirements assigned. Various design elements were reduced in scope due to significant budgetary constraints. Major alterations to the original plan included: (1) a VSP seismic survey was delayed to a later phase; (2) a new (larger) surface hole would be drilled rather than re-enter an existing well; (3) a 7-in. liner would be placed into the top of the Monterey target as quickly as possible to avoid problems with hole stability; (4) evaluation activities were reduced in scope; (5) geosteering observations for fracture access would be deduced from penetration rate, cuttings description and hydrocarbon in-flow; and (6) rather than use nitrogen, a novel air-injection MPD system was to be implemented. Drilling operations, delayed from the original schedule by capital constraints and lack of rig availability, were conducted from September 12 to November 11, 2004. The vertical and upper

  10. Pacific plate slab pull and intraplate deformation in the early Cenozoic

    NASA Astrophysics Data System (ADS)

    Butterworth, N. P.; Müller, R. D.; Quevedo, L.; O'Connor, J. M.; Hoernle, K.; Morra, G.

    2014-08-01

    Large tectonic plates are known to be susceptible to internal deformation, leading to a~range of phenomena including intraplate volcanism. However, the space and time dependence of intraplate deformation and its relationship with changing plate boundary configurations, subducting slab geometries, and absolute plate motion is poorly understood. We utilise a buoyancy-driven Stokes flow solver, BEM-Earth, to investigate the contribution of subducting slabs through time on Pacific plate motion and plate-scale deformation, and how this is linked to intraplate volcanism. We produce a series of geodynamic models from 62 to 42 Ma in which the plates are driven by the attached subducting slabs and mantle drag/suction forces. We compare our modelled intraplate deformation history with those types of intraplate volcanism that lack a clear age progression. Our models suggest that changes in Cenozoic subduction zone topology caused intraplate deformation to trigger volcanism along several linear seafloor structures, mostly by reactivation of existing seamount chains, but occasionally creating new volcanic chains on crust weakened by fracture zones and extinct ridges. Around 55 Ma, subduction of the Pacific-Izanagi ridge reconfigured the major tectonic forces acting on the plate by replacing ridge push with slab pull along its northwestern perimeter, causing lithospheric extension along pre-existing weaknesses. Large-scale deformation observed in the models coincides with the seamount chains of Hawaii, Louisville, Tokelau and Gilbert during our modelled time period of 62 to 42 Ma. We suggest that extensional stresses between 72 and 52 Ma are the likely cause of large parts of the formation of the Gilbert chain and that localised extension between 62 and 42 Ma could cause late-stage volcanism along the Musicians volcanic ridges. Our models demonstrate that early Cenozoic changes in Pacific plate driving forces only cause relatively minor changes in Pacific absolute plate motion

  11. Pacific Plate slab pull and intraplate deformation in the early Cenozoic

    NASA Astrophysics Data System (ADS)

    Butterworth, N. P.; Müller, R. D.; Quevedo, L.; O'Connor, J. M.; Hoernle, K.; Morra, G.

    2014-01-01

    Large tectonic plates are known to be susceptible to internal deformation, leading to a range of phenomena including intraplate volcanism. However, the space and time dependence of intraplate deformation and its relationship with changing plate boundary configurations, subducting slab geometries, and absolute plate motion is poorly understood. We utilise a buoyancy driven Stokes flow solver, BEM-Earth, to investigate the contribution of subducting slabs through time on Pacific Plate motion and plate-scale deformation, and how this is linked to intraplate volcanism. We produce a series of geodynamic models from 62 to 42 Ma in which the plates are driven by the attached subducting slabs and mantle drag/suction forces. We compare our modelled intraplate deformation history with those types of intraplate volcanism that lack a clear age progression. Our models suggest that changes in Cenozoic subduction zone topology caused intraplate deformation to trigger volcanism along several linear seafloor structures, mostly by reactivation of existing seamount chains, but occasionally creating new volcanic chains on crust weakened by fracture zones and extinct ridges. Around 55 Ma subduction of the Pacific-Izanagi ridge reconfigured the major tectonic forces acting on the plate by replacing ridge push with slab pull along its north-western perimeter, causing lithospheric extension along pre-existing weaknesses. Large scale deformation observed in the models coincides with the seamount chains of Hawaii, Louisville, Tokelau, and Gilbert during our modelled time period of 62 to 42 Ma. We suggest that extensional stresses between 72 and 52 Ma are the likely cause of large parts of the formation of the Gilbert chain and that localised extension between 62 and 42 Ma could cause late-stage volcanism along the Musicians Volcanic Ridges. Our models demonstrate that early Cenozoic changes in Pacific plate driving forces only cause relatively minor changes in Pacific absolute plate motions

  12. Standing sausage modes in curved coronal slabs

    NASA Astrophysics Data System (ADS)

    Pascoe, D. J.; Nakariakov, V. M.

    2016-09-01

    Context. Magnetohydrodynamic waveguides such as dense coronal loops can support standing modes. The ratios of the periods of oscillations for different longitudinal harmonics depend on the dispersive nature of the waveguide and so may be used as a seismological tool to determine coronal parameters. Aims: We extend models of standing sausage modes in low β coronal loops to include the effects of loop curvature. The behaviour of standing sausage modes in this geometry is used to explain the properties of observed oscillations that cannot be accounted for using straight loop models. Methods: We perform 2D numerical simulations of an oscillating coronal loop, modelled as a dense slab embedded in a potential magnetic field. The loop is field-aligned and so experiences expansion with height in addition to being curved. Standing sausage modes are excited by compressive perturbations of the loop and their properties are studied. Results: The spatial profiles of standing sausage modes are found to be modified by the expanding loop geometry typical for flaring loops and modelled by a potential magnetic field in our simulations. Longitudinal harmonics of order n > 1 have anti-nodes that are shifted towards the loop apex and the amplitude of anti-nodes near the loop apex is smaller than those near the loop footpoints. Conclusions: We find that the observation of standing sausage modes by the Nobeyama Radioheliograph in a flaring coronal loop on 12 January 2000 is consistent with interpretation in terms of the global mode (n = 1) and third harmonic (n = 3). This interpretation accounts for the period ratio and spatial structure of the observed oscillations.

  13. Risk analysis for dry snow slab avalanche release by skier triggering

    NASA Astrophysics Data System (ADS)

    McClung, David

    2013-04-01

    Risk analysis is of primary importance for skier triggering of avalanches since human triggering is responsible for about 90% of deaths from slab avalanches in Europe and North America. Two key measureable quantities about dry slab avalanche release prior to initiation are the depth to the weak layer and the slope angle. Both are important in risk analysis. As the slope angle increases, the probability of avalanche release increases dramatically. As the slab depth increases, the consequences increase if an avalanche releases. Among the simplest risk definitions is (Vick, 2002): Risk = (Probability of failure) x (Consequences of failure). Here, these two components of risk are the probability or chance of avalanche release and the consequences given avalanche release. In this paper, for the first time, skier triggered avalanches were analyzed from probability theory and its relation to risk for both the D and . The data consisted of two quantities : (,D) taken from avalanche fracture line profiles after an avalanche has taken place. Two data sets from accidentally skier triggered avalanches were considered: (1) 718 for and (2) a set of 1242 values of D which represent average values along the fracture line. The values of D were both estimated (about 2/3) and measured (about 1/3) by ski guides from Canadian Mountain Holidays CMH). I also analyzed 1231 accidentally skier triggered avalanches reported by CMH ski guides for avalanche size (representing destructive potential) on the Canadian scale. The size analysis provided a second analysis of consequences to verify that using D. The results showed that there is an intermediate range of both D and with highest risk. ForD, the risk (product of consequences and probability of occurrence) is highest for D in the approximate range 0.6 m - 1.0 m. The consequences are low for lower values of D and the chance of release is low for higher values of D. Thus, the highest product is in the intermediate range. For slope angles

  14. Structure of turbulent flow in a slab mold

    NASA Astrophysics Data System (ADS)

    Ramírez-López, Pável; Demedices, L. G.; Dávila, O.; Sánchez-Pérez, R.; Morales, R. D.

    2005-12-01

    The structure of the turbulent flow in a slab mold is studied using a water model, various experimental techniques, and mathematical simulations. The meniscus stability depends on the turbulence structure of the flow in the mold; mathematical simulations using the k-ɛ model and the Reynolds-stress model (RSM) indicate that the latter is better at predicting the meniscus profile for a given casting speed. Reynolds stresses and flow vorticity measured through the particle-image velocimetry (PIV) technique are very close to those predicted by the RSM model, and maximum and minimum values across the jet diameter are reported. The backflow in the upper side of the submerged entry nozzle (SEN) port (for a fixed SEN design) depends on the casting speed and disappears, increasing this process parameter. At low casting speeds, the jet does not report enough dissipation of energy, so the upper flow roll is able to reach the SEN port. At high casting speeds, the jet energy is strongly dissipated inside the SEN port, the narrow wall, and in the mold corner, weakening the momentum transfer of the upper flow roll, which is unable to reach the SEN port. At low casting speeds, meniscus instability is observed very close to the SEN, while at high casting speeds, this instability is observed in the mold corner. An optimum casting speed is reported where complete meniscus stability was observed. The flow structure at the free surface indicates a composite structure of islands with large gradients of velocity at high casting speeds. These velocity gradients are responsible for the meniscus instability.

  15. Appraisal of fracture sampling methods and a new workflow to characterise heterogeneous fracture networks at outcrop

    NASA Astrophysics Data System (ADS)

    Watkins, Hannah; Bond, Clare E.; Healy, Dave; Butler, Robert W. H.

    2015-03-01

    Characterising fractures at outcrop for use as analogues to fractured reservoirs can use several methods. Four important fracture data collection methods are linear scanline sampling, areal sampling, window sampling and circular scanline sampling. In regions of homogeneous fracture networks these methods are adequate to characterise fracture patterns for use as outcrop analogues, however where fractures are heterogeneous, it is more difficult to characterise fracture networks and a different approach is needed. We develop a workflow for fracture data collection in a region of heterogeneous fractures in a fold and thrust belt, which we believe has applicability to a wide variety of fracture networks in different tectonic settings. We use an augmented circular scanline method, along with areal sampling to collect a range of fracture attribute data, including orientation, length, aperture, spatial distribution and intensity. This augmented circular scanline method more than halves the time taken for data collection, provides accurate, unbiased data that is representative of local fracture network attributes and involves data collection of a wider range of fracture attributes than other sampling techniques alone.

  16. When do fractured media become seismically anisotropic? Some implications on quantifying fracture properties

    NASA Astrophysics Data System (ADS)

    Yousef, B. M.; Angus, D. A.

    2016-06-01

    Fractures are pervasive features within the Earth's crust and they have a significant influence on the multi-physical response of the subsurface. The presence of coherent fracture sets often leads to observable seismic anisotropy enabling seismic techniques to remotely locate and characterise fracture systems. In this study, we confirm the general scale-dependence of seismic anisotropy and provide new results specific to shear-wave splitting (SWS). We find that SWS develops under conditions when the ratio of wavelength to fracture size (λS / d) is greater than 3, where Rayleigh scattering from coherent fractures leads to an effective anisotropy such that effective medium model (EMM) theory is qualitatively valid. When 1 <λS / d < 3 there is a transition from Rayleigh to Mie scattering, where no effective anisotropy develops and hence the SWS measurements are unstable. When λS / d < 1 we observe geometric scattering and begin to see behaviour similar to transverse isotropy. We find that seismic anisotropy is more sensitive to fracture density than fracture compliance ratio. More importantly, we observe that the transition from scattering to an effective anisotropic regime occurs over a propagation distance between 1 and 2 wavelengths depending on the fracture density and compliance ratio. The existence of a transition zone means that inversion of seismic anisotropy parameters based on EMM will be fundamentally biased. More importantly, we observe that linear slip EMM commonly used in inverting fracture properties is inconsistent with our results and leads to errors of approximately 400% in fracture spacing (equivalent to fracture density) and 60% in fracture compliance. Although EMM representations can yield reliable estimates of fracture orientation and spatial location, our results show that EMM representations will systematically fail in providing quantitatively accurate estimates of other physical fracture properties, such as fracture density and compliance

  17. Electronics reliability fracture mechanics. Volume 2: Fracture mechanics

    NASA Astrophysics Data System (ADS)

    Kallis, J.; Duncan, L.; Buechler, D.; Backes, P.; Sandkulla, D.

    1992-05-01

    This is the second of two volumes. The other volume (WL-TR-92-3015) is 'Causes of Failures of Shop Replaceable Units and Hybrid Microcircuits.' The objective of the Electronics Reliability Fracture Mechanics (ERFM) program was to develop and demonstrate a life prediction technique for electronic assemblies, when subjected to environmental stresses of vibration and thermal cycling, based upon the mechanical properties of the materials and packaging configurations which make up an electronic system. The application of fracture mechanics to microscale phenomena in electronic assemblies was a pioneering research effort. The small scale made the experiments very difficult; for example, the 1-mil-diameter bond wires in microelectronic devices are 1/3 the diameter of a human hair. A number of issues had to be resolved to determine whether a fracture mechanics modelling approach is correct for the selected failures; specifically, the following two issues had to be resolved: What fraction of the lifetime is spent in crack initiation? Are macro fracture mechanics techniques, used in large structures such as bridges, applicable to the tiny structures in electronic equipment? The following structural failure mechanisms were selected for modelling: bondwire fracture from mechanical cycling; bondwire fracture from thermal (power) cycling; plated through hole (PTH) fracture from thermal cycling. The bondwire fracture test specimens were A1-1 percent Si wires, representative of wires used in the parts in the modules selected for detailed investigation in this program (see Vol. 1 of this report); 1-mil-diameter wires were tested in this program. The PTH test specimens were sections of 14-layer printed wiring boards of the type used.

  18. Pediatric facial fractures: evolving patterns of treatment.

    PubMed

    Posnick, J C; Wells, M; Pron, G E

    1993-08-01

    This study reviews the treatment of facial trauma between October 1986 and December 1990 at a major pediatric referral center. The mechanism of injury, location and pattern of facial fractures, pattern of facial injury, soft tissue injuries, and any associated injuries to other organ systems were recorded, and fracture management and perioperative complications reviewed. The study population consisted of 137 patients who sustained 318 facial fractures. Eighty-one patients (171 fractures) were seen in the acute stage, and 56 patients (147 fractures) were seen for reconstruction of a secondary deformity. Injuries in boys were more prevalent than in girls (63% versus 37%), and the 6- to 12-year cohort made up the largest group (42%). Most fractures resulted from traffic-related accidents (50%), falls (23%), or sports-related injuries (15%). Mandibular (34%) and orbital fractures (23%) predominated; fewer midfacial fractures (7%) were sustained than would be expected in a similar adult population. Three quarters of the patients with acute fractures required operative intervention. Closed reduction techniques with maxillomandibular fixation were frequently chosen for mandibular condyle fractures and open reduction techniques (35%) for other regions of the facial skeleton. When open reduction was indicated, plate-and-screw fixation was the preferred method of stabilization (65%). The long-term effects of the injuries and the treatment given on facial growth remain undetermined. Perioperative complication rates directly related to the surgery were low. PMID:8336220

  19. Pediatric facial fractures: evolving patterns of treatment.

    PubMed

    Posnick, J C; Wells, M; Pron, G E

    1993-08-01

    This study reviews the treatment of facial trauma between October 1986 and December 1990 at a major pediatric referral center. The mechanism of injury, location and pattern of facial fractures, pattern of facial injury, soft tissue injuries, and any associated injuries to other organ systems were recorded, and fracture management and perioperative complications reviewed. The study population consisted of 137 patients who sustained 318 facial fractures. Eighty-one patients (171 fractures) were seen in the acute stage, and 56 patients (147 fractures) were seen for reconstruction of a secondary deformity. Injuries in boys were more prevalent than in girls (63% versus 37%), and the 6- to 12-year cohort made up the largest group (42%). Most fractures resulted from traffic-related accidents (50%), falls (23%), or sports-related injuries (15%). Mandibular (34%) and orbital fractures (23%) predominated; fewer midfacial fractures (7%) were sustained than would be expected in a similar adult population. Three quarters of the patients with acute fractures required operative intervention. Closed reduction techniques with maxillomandibular fixation were frequently chosen for mandibular condyle fractures and open reduction techniques (35%) for other regions of the facial skeleton. When open reduction was indicated, plate-and-screw fixation was the preferred method of stabilization (65%). The long-term effects of the injuries and the treatment given on facial growth remain undetermined. Perioperative complication rates directly related to the surgery were low.

  20. Receiver Function Study of the Peruvian Flat-Slab Region: Initial Results from PULSE

    NASA Astrophysics Data System (ADS)

    Bishop, B.; Beck, S. L.; Zandt, G.; Kumar, A.; Wagner, L. S.; Long, M. D.; Tavera, H.

    2013-12-01

    The largest segment of flat slab subduction in the world occurs beneath Peru where the distribution of slab earthquakes indicates the Nazca plate subducts nearly horizontally below the Andes. The presumably buoyant Nazca Ridge subducts at the southern end of this shallow subduction segment which has been linked to the cessation of active arc volcanism within the segment of the Andes between 3°S and 15°S. We deployed 40 broadband seismic stations as part of the PerU Lithosphere and Slab Experiment (PULSE) to investigate the flat slab subduction processes beneath the Peruvian Andes between 10.5°S and 15°S. As one component of a multi-technique seismological study, we have calculated Receiver Functions from PULSE seismic data to create Common Conversion Point stacks utilizing a 1-D velocity structure with Vp of 6.2 km/s to 60 km depth, 8.1 km/s from 60 to 200 km depth, and a Vp/Vs ratio of 1.8 to provide preliminary constraints on crustal-scale structures near the subducting Nazca Ridge. Forward modeling of results from individual stations was carried out to provide additional constraints on more localized crustal variations. These results provide estimates for the thickness of the continental crust of the overriding South American Plate as well as the first regional images of a discontinuous oceanic Moho of the subducted Nazca Plate. Receiver function results show a strong P-to-S conversion from the continental Moho indicating the presence of significantly thickened crust within the central Peruvian Andes, reaching thicknesses of 50 to more than 60 kilometers and extending eastward into the Subandean region. A significant change in crustal thickness is present in the Eastern Cordillera northeast of Cuzco, stepping from approximately 62 km to 55 km, which matches prior crustal models based on gravity data. A number of high amplitude arrivals indicate the top of a low velocity layer at approximately 12-15 km depth throughout the PULSE study region, roughly

  1. Fractures of the growing mandible.

    PubMed

    Kushner, George M; Tiwana, Paul S

    2009-03-01

    Oral and maxillofacial surgeons must constantly weigh the risks of surgical intervention for pediatric mandible fractures against the wonderful healing capacity of children. The majority of pediatric mandibular fractures can be managed with closed techniques using short periods of maxillomandibular fixation or training elastics alone. Generally, the use of plate- and screw-type internal fixation is reserved for difficult fractures. This article details general and special considerations for this surgery including: craniofacial growth & development, surgical anatomy, epidemiology evaluation, various fractures, the role rigid internal fixation and the Risdon cable in pediatric maxillofacial trauma. It concludes with suggestions concerning long-term follow-up care in light of the mobility, insurance obstacles, and family dynamics facing the patient population.

  2. Modeling the thin-slab continuous-casting mold

    SciTech Connect

    O'Connor, T.G. . Applied Superconductivity Group); Dantzig, J.A. . Dept. of Mechanical and Industrial Engineering)

    1994-06-01

    A three-dimensional mathematical model has been developed to compute the thermomechanical state in the mold of thin-slab continuous casters. The thin-slab mold differs from those used in conventional slab casters in that the upper portion of the broad side walls defines a funnel-shaped chamber which allows the nozzle to be submerged into the liquid metal. The chamber converges with distance down the mold, reducing to the rectangular cross section of the finished casting near the mold exit. The new mold, along with casting speeds up to 6 m/min, allows slabs to be cast 50--60 mm thick, compared with 150 to 350 mm in conventional continuous slab casting. However, the mold shape and high casting speed lead to higher mold temperatures and shorter mold life than are found in conventional slab casters. In this article, the author develop mathematical models of the process to determine the role of various process parameters in determining the mold life. Finite-element analysis is used to determine the temperatures in the mold and cast slab, and these data are then used in an elastic-viscoplastic analysis to investigate the deformation of the mold wall in service. Cyclic inelastic strains up to 1.75 pct are found in a region below the meniscus along the funnel edge. These large strains result from the combination of locally high temperatures coupled with geometric restraint of the mold. The deformation leads to short mold life because of thermal fatigue cracking of the mold. The computed locations and time to failure of the mold in fatigue agree very well with observations of the appearance of mold surface cracks in an operating caster. The models are also used to develop an improved mold design.

  3. Modeling the thin-slab continuous-casting mold

    NASA Astrophysics Data System (ADS)

    Oconnor, Thomas G.; Dantzig, Jonathan A.

    1994-06-01

    A three-dimensional mathematical model has been developed to compute the thermomechanical state in the mold of thin-slab continuous casters. The thin-slab mold differs from those used in conventional slab casters in that the upper portion of the broad side walls defines a funnel-shaped chamber which allows the nozzle to be submerged into the liquid metal. The chamber converges with distance down the mold, reducing to the rectangular cross section of the finished casting near the mold exit. The new mold, along with casting speeds up to 6 m/min, allows slabs to be cast 50 60 mm thick, compared with 150 to 350 mm in conventional continuous slab casting. However, the mold shape and high casting speed lead to higher mold temperatures and shorter mold life than are found in conventional slab casters. In this article, we develop mathematical models of the process to determine the role of various process parameters in determining the mold life. Finite-element analysis is used to determine the temperatures in the mold and cast slab, and these data are then used in an elastic-viscoplastic analysis to investigate the deformation of the mold wall in service. Cyclic inelastic strains up to 1.75 Pct are found in a region below the meniscus along the funnel edge. These large strains result from the combination of locally high temperatures coupled with geometric restraint of the mold. The deformation leads to short mold life because of thermal fatigue cracking of the mold. The computed locations and time to failure of the mold in fatigue agree very well with observations of the appearance of mold surface cracks in an operating caster. The models are also used to develop an improved mold design.

  4. Can slabs melt beneath forearcs in hot subduction zones?

    NASA Astrophysics Data System (ADS)

    Ribeiro, J.; Maury, R.; Gregoire, M.

    2015-12-01

    At subduction zones, thermal modeling predict that the shallow part of the downgoing oceanic crust (< 80 - 100 km depth to the slab) is usually too cold to cross the water-rich solidus and melts beneath the forearc. Yet, the occasional occurrence of adakites, commonly considered as slab melts, in the forearc region challenges our understanding of the shallow subduction processes. Adakites are unusual felsic rocks commonly associated with asthenospheric slab window opening or fast subduction of young (< 25 Ma) oceanic plate that enable slab melting at shallow depths; but their genesis has remained controversial. Here, we present a new approach that provides new constraints on adakite petrogenesis in hot subduction zones (the Philippines) and above an asthenospheric window (Baja California, Mexico). We use amphibole compositions to estimate the magma storage depths and the composition of the parental melts to test the hypothesis that adakites are pristine slab melts. We find that adakites from Baja California and Philippines formed by two distinct petrogenetic scenarios. In Baja California, hydrous mantle melts mixed/mingled with high-pressure (HP) adakite-type, slab melts within a lower crustal (~30 km depth) magma storage region before stalling into the upper arc crust (~7-15 km depth). In contrast, in the Philippines, primitive mantle melts stalled and crystallized within lower and upper crustal magma storage regions to produce silica-rich melts with an adakitic signature. Thereby, slab melting is not required to produce an adakitic geochemical fingerprint in hot subduction zones. However, our results also suggest that the downgoing crust potentially melted beneath Baja California.

  5. Modeling the surface photovoltage of silicon slabs with varying thickness.

    PubMed

    Vazhappilly, Tijo; Kilin, Dmitri S; Micha, David A

    2015-04-10

    The variation with thickness of the energy band gap and photovoltage at the surface of a thin semiconductor film are of great interest in connection with their surface electronic structure and optical properties. In this work, the change of a surface photovoltage (SPV) with the number of layers of a crystalline silicon slab is extracted from models based on their atomic structure. Electronic properties of photoexcited slabs are investigated using generalized gradient and hybrid density functionals, and plane wave basis sets. Si(1 1 1) surfaces have been terminated by hydrogen atoms to compensate for dangling bonds and have been described by large supercells with periodic boundary conditions. Calculations of the SPV of the Si slabs have been done in terms of the reduced density matrix of the photoactive electrons including dissipative effects due to their interaction with medium phonons and excitons. Surface photovoltages have been calculated for model Si slabs with 4-12, and 16 layers, to determine convergence trends versus slab thickness. Band gaps and the inverse of the SPVs have been found to scale nearly linearly with the inverse thickness of the slab, while the electronic density of states increases quadratically with thickness. Our calculations show the same trends as experimental values indicating band gap reduction and absorption enhancement for Si films of increasing thickness. Simple arguments on confined electronic structures have been used to explain the main effects of changes with slab thickness. A procedure involving shifted electron excitation energies is described to improve results from generalized gradient functionals so they can be in better agreement with the more accurate but also more computer intensive values from screened exchange hybrid functionals.

  6. Digital Image Processing Techniques for Enhancement and Classification of MR1 Side Scan Sonar Imagery and Preliminary Results of Manganese Nodule Occurrence between the Clarion and Clipperton Fracture Zones, NE Equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Kim, H.; Park, C.; Park, J.; Kim, K.

    2004-12-01

    The recent growth in the production rate of digital side scan sonar images, coupled with the rapid expansion of systematic seafloor exploration programs, has created a need for fast and quantitative means of processing seafloor imagery. A number of numerical techniques used to enhance and classify imagery produced by long range side scan sonar (MR1) in the Clarion and Clippertion Fracture Zones, NE equatorial Pacific. Side scan sonar imagery is traditionally interpreted visually and qualitatively by experts. Textural Analysis enables a more objective approach, supplementing the interpreter with reliable quantitative results. Grey-level co-occurrence matrices describe numerically textual information and detect subtle details invisible to the human eyes. The area between the Clarion and Clipperton fracture zones (NE equatorial Pacific) is one of the highest manganese nodule abundance in the world oceans. A detailed analysis of MR1 sonar images and ground truth - free-fall grab (FFG) data in the area, reveals a close relationship between sonar characters of seafloor and manganese nodule occurrence. The close relationship between distribution of sonar imagery and manganese nodule abundance implies that seafloor topography and sediment thickness are important controlling factors for occurrence of manganese nodules.

  7. HUMERAL SHAFT FRACTURES

    PubMed Central

    Benegas, Eduardo; Ferreira Neto, Arnaldo Amado; Neto, Raul Bolliger; Santis Prada, Flavia de; Malavolta, Eduardo Angeli; Marchitto, Gustavo Oliveira

    2015-01-01

    Humeral shaft fractures (HSFs) represent 3% of the fractures of the locomotor apparatus, and the middle third of the shaft is the section most affected. In the majority of cases, it is treated using nonsurgical methods, but surgical indications in HSF cases are increasingly being adopted. The diversity of opinions makes it difficult to reach a consensus regarding the types of osteosynthesis, surgical technique and quantity and quality of synthesis materials that should be used. It would appear that specialists are far from reaching a consensus regarding the best method for surgical treatment of HSFs. We believe that less invasive methods, which favor relative stability, are the most appropriate methods, since the most feared complications are less frequent. PMID:27019833

  8. Continental collision and slab break-off: A comparison of 3-D numerical models with observations

    NASA Astrophysics Data System (ADS)

    van Hunen, Jeroen; Allen, Mark B.

    2011-02-01

    Conditions and dynamics of subduction-collision and subsequent 3-D slab break-off and slab tear propagation are quantified, for the first time, using fully dynamic numerical models. Model results indicate that collision after the subduction of old, strong subducting oceanic slab leads to slab break-off at 20-25 Myr after the onset of continental collision, and subsequently a slab tear migrates more or less horizontally through the slab with a propagation speed of 100-150 mm/yr. In contrast, young, weak oceanic slabs show the first break-off already 10 Myr after continental collision, and can experience tear migration rates up to 800 mm/yr. Slab strength plays a more important role in the timing of slab break-off and the speed of a propagating slab tear than (negative) slab buoyancy does. Slab break-off is viable even for slabs that are supported by the viscosity jump and phase change between the upper and lower mantle. The density of the oceanic slab and the subducting continental block is important for the amount of continental subduction and the depth of slab break-off. A 40-km thick continental crust can be buried to depths greater than 200 km, although this maximum depth is significantly less for younger or very weak slabs, or thicker continental crust. Slab break-off typically starts at a depth of 300 km, mostly independent of mantle rheology, but, like continental crustal burial, can be shallower for young or buoyant plates. Our 3-D models illustrate how, due to the difference in necking in 2-D and 3-D, break-off has an intrinsic small preference to start as a slab window within the slab's interior, rather than as a slab tear at the slab edge. However, any significant asymmetry in the collision setting, e.g. earlier collision at one end of the subduction zone, would override this, and leads to slab tearing starting near one edge of the slab. These results put important new constraints on the dynamics of the collision and subsequent slab break-off for modern

  9. Influence of Rock Fabric on Hydraulic Fracture Propagation: Laboratory Study

    NASA Astrophysics Data System (ADS)

    Stanchits, S. A.; Desroches, J.; Burghardt, J.; Surdi, A.; Whitney, N.

    2014-12-01

    Massive hydraulic fracturing is required for commercial gas production from unconventional reservoirs. These reservoirs are often highly fractured and heterogeneous, which may cause significant fracture complexity and also arrest propagation of hydraulic fractures, leading to production decrease. One of the goals of our study was to investigate the influence of rock fabric features on near-wellbore fracture geometry and complexity. We performed a series of laboratory tests on Niobrara outcrop shale blocks with dimensions of 30 x 30 x 36 inches in a true-triaxial loading frame. Acoustic Emission (AE) technique was applied to monitor hydraulic fracture initiation and dynamics of fracture propagation. After the tests, the shape of the created hydraulic fracture was mapped by goniometry technique. To estimate fracture aperture, particles of different sizes were injected with fracturing fluid. In all tests, AE analysis indicated hydraulic fracture initiation prior to breakdown or the maximum of wellbore pressure. In most tests, AE analysis revealed asymmetrical hydraulic fracture shapes. Post-test analysis demonstrated good correspondence of AE results with the actual 3D shape of the fracture surface map. AE analysis confirmed that in some of these tests, the hydraulic fracture approached one face of the block before the maximum wellbore pressure had been reached. We have found that in such cases the propagation of hydraulic fracture in the opposite direction was arrested by the presence of mineralized interfaces. Mapping the distribution of injected particles confirmed the creation of a narrow-width aperture in the vicinity of pre-existing interfaces, restricting fracture conductivity. Based on the results of our study, we concluded that the presence of planes of weakness, such as mineralized natural fractures, can result in the arrest of hydraulic fracture propagation, or in poor fracture geometries with limited aperture, that in turn could lead to high net pressure

  10. Tomographic imaging of the effects of Peruvian flat slab subduction on the Nazca slab and surrounding mantle under central and southern Peru

    NASA Astrophysics Data System (ADS)

    Scire, A. C.; Zandt, G.; Beck, S. L.; Bishop, B.; Biryol, C. B.; Wagner, L. S.; Long, M. D.; Minaya, E.; Tavera, H.

    2014-12-01

    The modern central Peruvian Andes are dominated by a laterally extensive region of flat slab subduction. The Peruvian flat slab extends for ~1500 km along the strike of the Andes, correlating with the subduction of the Nazca Ridge in the south and the theorized Inca Plateau in the north. We have used data from the CAUGHT and PULSE experiments for finite frequency teleseismic P- and S-wave tomography to image the Nazca slab in the upper mantle below 95 km depth under central Peru between 10°S and 18°S as well as the surrounding mantle. Since the slab inboard of the subducting Nazca Ridge is mostly aseismic, our results provide important constraints on the geometry of the subducting Nazca slab in this region. Our images of the Nazca slab suggest that steepening of the slab inboard of the subducting Nazca Ridge locally occurs ~100 km further inland than was indicated in previous studies. The region where we have imaged the steepening of the Nazca slab inboard of the Nazca Ridge correlates with the location of the Fitzcarrald Arch, a long wavelength upper plate topographic feature which has been suggested to be a consequence of ridge subduction. When the slab steepens inboard of the flat slab region, it does so at a very steep (~70°) angle. The transition from the Peruvian flat slab to the more normally dipping slab south of 16°S below Bolivia is characterized by an abrupt bending of the slab anomaly in the mantle in response to the shift from flat to normal subduction. The slab anomaly appears to be intact south of the Nazca Ridge with no evidence for tearing of the slab in response to the abrupt change in slab dip. A potential tear in the slab is inferred from an observed offset in the slab anomaly north of the Nazca Ridge extending subparallel to the ridge axis between 130 and 300 km depth. A high amplitude (-5-6%) slow S-wave velocity anomaly is observed below the projection of the Nazca Ridge. This anomaly appears to be laterally confined to the mantle

  11. Fluid Production Induced Stress Analysis Surrounding an Elliptic Fracture

    NASA Astrophysics Data System (ADS)

    Pandit, Harshad Rajendra

    Hydraulic fracturing is an effective technique used in well stimulation to increase petroleum well production. A combination of multi-stage hydraulic fracturing and horizontal drilling has led to the recent boom in shale gas production which has changed the energy landscape of North America. During the fracking process, highly pressurized mixture of water and proppants (sand and chemicals) is injected into to a crack, which fractures the surrounding rock structure and proppants help in keeping the fracture open. Over a longer period, however, these fractures tend to close due to the difference between the compressive stress exerted by the reservoir on the fracture and the fluid pressure inside the fracture. During production, fluid pressure inside the fracture is reduced further which can accelerate the closure of a fracture. In this thesis, we study the stress distribution around a hydraulic fracture caused by fluid production. It is shown that fluid flow can induce a very high hoop stress near the fracture tip. As the pressure gradient increases stress concentration increases. If a fracture is very thin, the flow induced stress along the fracture decreases, but the stress concentration at the fracture tip increases and become unbounded for an infinitely thin fracture. The result from the present study can be used for studying the fracture closure problem, and ultimately this in turn can lead to the development of better proppants so that prolific well production can be sustained for a long period of time.

  12. Fossil slabs attached to unsubducted fragments of the Farallon plate

    PubMed Central

    Wang, Yun; Forsyth, Donald W.; Rau, Christina J.; Carriero, Nina; Schmandt, Brandon; Gaherty, James B.; Savage, Brian

    2013-01-01

    As the Pacific–Farallon spreading center approached North America, the Farallon plate fragmented into a number of small plates. Some of the microplate fragments ceased subducting before the spreading center reached the trench. Most tectonic models have assumed that the subducting oceanic slab detached from these microplates close to the trench, but recent seismic tomography studies have revealed a high-velocity anomaly beneath Baja California that appears to be a fossil slab still attached to the Guadalupe and Magdalena microplates. Here, using surface wave tomography, we establish the lateral extent of this fossil slab and show that it is correlated with the distribution of high-Mg andesites thought to derive from partial melting of the subducted oceanic crust. We also reinterpret the high seismic velocity anomaly beneath the southern central valley of California as another fossil slab extending to a depth of 200 km or more that is attached to the former Monterey microplate. The existence of these fossil slabs may force a reexamination of models of the tectonic evolution of western North America over the last 30 My. PMID:23509274

  13. Fossil slabs attached to unsubducted fragments of the Farallon plate.

    PubMed

    Wang, Yun; Forsyth, Donald W; Rau, Christina J; Carriero, Nina; Schmandt, Brandon; Gaherty, James B; Savage, Brian

    2013-04-01

    As the Pacific-Farallon spreading center approached North America, the Farallon plate fragmented into a number of small plates. Some of the microplate fragments ceased subducting before the spreading center reached the trench. Most tectonic models have assumed that the subducting oceanic slab detached from these microplates close to the trench, but recent seismic tomography studies have revealed a high-velocity anomaly beneath Baja California that appears to be a fossil slab still attached to the Guadalupe and Magdalena microplates. Here, using surface wave tomography, we establish the lateral extent of this fossil slab and show that it is correlated with the distribution of high-Mg andesites thought to derive from partial melting of the subducted oceanic crust. We also reinterpret the high seismic velocity anomaly beneath the southern central valley of California as another fossil slab extending to a depth of 200 km or more that is attached to the former Monterey microplate. The existence of these fossil slabs may force a reexamination of models of the tectonic evolution of western North America over the last 30 My.

  14. Systematic variation in the depths of slabs beneath arc volcanoes

    USGS Publications Warehouse

    England, P.; Engdahl, R.; Thatcher, W.

    2004-01-01

    The depths to the tops of the zones of intermediate-depth seismicity beneath arc volcanoes are determined using the hypocentral locations of Engdahl et al. These depths are constant, to within a few kilometres, within individual arc segments, but differ by tens of kilometres from one arc segment to another. The range in depths is from 65 km to 130 km, inconsistent with the common belief that the volcanoes directly overlie the places where the slabs reach a critical depth that is roughly constant for all arcs. The depth to the top of the intermediate-depth seismicity beneath volcanoes correlates neither with age of the descending ocean floor nor with the thermal parameter of the slab. This depth does, however, exhibit an inverse correlation with the descent speed of the subducting plate, which is the controlling factor both for the thermal structure of the wedge of mantle above the slab and for the temperature at the top of the slab. We interpret this result as indicating that the location of arc volcanoes is controlled by a process that depends critically upon the temperature at the top of the slab, or in the wedge of mantle, immediately below the volcanic arc.

  15. Fossil slabs attached to unsubducted fragments of the Farallon plate.

    PubMed

    Wang, Yun; Forsyth, Donald W; Rau, Christina J; Carriero, Nina; Schmandt, Brandon; Gaherty, James B; Savage, Brian

    2013-04-01

    As the Pacific-Farallon spreading center approached North America, the Farallon plate fragmented into a number of small plates. Some of the microplate fragments ceased subducting before the spreading center reached the trench. Most tectonic models have assumed that the subducting oceanic slab detached from these microplates close to the trench, but recent seismic tomography studies have revealed a high-velocity anomaly beneath Baja California that appears to be a fossil slab still attached to the Guadalupe and Magdalena microplates. Here, using surface wave tomography, we establish the lateral extent of this fossil slab and show that it is correlated with the distribution of high-Mg andesites thought to derive from partial melting of the subducted oceanic crust. We also reinterpret the high seismic velocity anomaly beneath the southern central valley of California as another fossil slab extending to a depth of 200 km or more that is attached to the former Monterey microplate. The existence of these fossil slabs may force a reexamination of models of the tectonic evolution of western North America over the last 30 My. PMID:23509274

  16. Cenozoic Plume-Slab Interaction Beneath the Pacific Northwest

    NASA Astrophysics Data System (ADS)

    Obrebski, M. J.; Allen, R. M.; Hung, S.; Pollitz, F. F.

    2009-12-01

    Here we present new images of the structure beneath the Pacific Northwest obtained by inverting both compressional and shear teleseismic body waves and using finite-frequency sensitivity kernels. The models use all available seismic data from the Earthscope Transportable Array, regional seismic networks and two Flexible Array experiments (Mendocino and FACES experiments) deployed on the west coast. By picking P, S and SKS arrivals manually and estimating station-to-station relative arrival times through cross correlation of the waveforms, we select only the highest quality data. East from the Juan de Fuca slab and north from the Mendocino Triple Junction, the mantle structure is dominated by high velocity blocks that are likely to be fragments of the Farallon slab. In the middle of the slab fragments, both our compressional (DNA09-P) and shear (DNA09-S) velocity models show a continuous low velocity anomaly that extends from the Yellowstone Caldera down into the lower mantle. We interpret this feature as a deep-seated mantle plume. The striking contrast between the slab-dominated mantle north from the MTJ and the continuous deep-seated Yellowstone mantle plume suggests the plume disrupted the Farallon slab during its ascent to the surface.

  17. Investigation of fracture-matrix interaction: Preliminary experiments in a simple system

    SciTech Connect

    Foltz, S.D.; Tidwell, V.C.; Glass, R.J.; Sobolik, S.R.

    1992-12-31

    Paramount to the modeling of unsaturated flow and transport through fractured porous media is a clear understanding of the processes controlling fracture-matrix interaction. As a first step toward such an understanding, two preliminary experiments have been performed to investigate the influence of matrix imbibition on water percolation through unsaturated fractures in the plane normal to the fracture. Test systems consisted of thin slabs of either tuff or an analog material cut by a single vertical fracture into which a constant fluid flux was introduced. Transient moisture content and solute concentration fields were imaged by means of x-ray absorption. Flow fields associated with the two different media were significantly different owing to differences in material properties relative to the imposed flux. Richards` equation was found to be a valid means of modeling the imbibition of water into the tuff matrix from a saturated fracture for the current experiment.

  18. The nature of fracturing and stress distribution in quartzite around the 1128-M (3700-FT) level of the crescent mine, Coeur d'Alene mining district, Idaho

    USGS Publications Warehouse

    Miller, C.H.; Skinner, E.H.

    1980-01-01

    Silver and copper are the principal ores mined from the quartzite at the Crescent mine. Both the main ore-bearing veins and foliation in the quartzite are parallel to the nearly vertical formational contacts. Anisotropy of the quartzite is indicated by both dynamic and static tests. Disking and breakage of core from holes perpendicular to the foliation are about twice what they are in core from holes parallel to foliation. Natural cleavage as well as slabbing and blasting fractures around the tunnels are also controlled by the foliation. Extensive overcore deformation measurements indicate that most of the influence of the tunnels on the "free" stress field is between the rib and a depth of 2.7 m (1 tunnel diameter). The maximum principal stress axis in the free field is nearly horizontal; its magnitude is not much greater than the vertical component and calculations indicate a nearly hydrostatic free stress field. Stress considerably greater than the free field was measured between about 0.3-2.7 m behind the rib and is caused by a transfer of load from above the tunnel opening. Peak stress is in the vertical direction and about 1.7 m behind the rib. An air-injection survey shows that high permeabilities are confined to the highly fractured annulus around a tunnel to a depth of at least 0.6 m. Air-injection measurements could be taken in the interval of about 0.6-1.8 m, but more fractures with high permeabilities may also be present in the annulus from about 0.6-1.2 m. Permeabilities measured deeper than about 1.8 m by the air-injection technique are either very low or nonexistent. The absence of open and noncontinuous fractures beyond about 1.8 m is also indicated by very low porosities and permeabilities of core, very high stresses (which presumably would close fractures), the lack of stains or secondary fillings in disking fractures, a conspicuous lack of ground water in the tunnels, and the fact that fractures encountered in an experimental 0.9-m tunnel did not

  19. The carbon-bearing phases in the subducted slabs under the lower mantle condition

    NASA Astrophysics Data System (ADS)

    Maeda, F.; Ohtani, E.; Kamada, S.; Sakamaki, T.; Ohishi, Y.; Hirao, N.

    2014-12-01

    Carbon, which is one of the most important volatile elements in the solar system, is suggested to be stored in the deep part of the Earth. The evidence for the deep carbon is found in super-deep diamonds or estimations of carbon fluxes between the surface and interior of the Earth. The candidates of a carbon-source into the mantle are subducting slabs. Therefore, it is important for the studying of Deep Carbon Cycle to reveal the reactions related to carbon-bearing phases in the slabs descending into the lower mantle. The MgCO3-SiO2 system is considered to constrain the carbon-bearing phases in the slabs since following reactions can occur under the lower mantle conditions: MgCO3 (magnesite) + SiO2 (stishovite) → MgSiO3 (perovskite) + CO2CO2 → C (diamond) + O2The phase boundary in the MgCO3-SiO2 system has ambiguity because of the contradiction between the previous studies. We aimed to reconcile this contradiction and determine the potential carbon-bearing phases in the deep subducting slabs. We have investigated the reaction between MgCO3 and SiO2 up to about 100 GPa and 3000 K using the double sided laser heated diamond anvil cell combined with the in-situ synchrotron XRD technique and Raman spectroscopy. The starting material was a powered 1:1 (in mole fraction) mixture of natural magnesite (Brazil, Bahia) and reagent α-quartz. XRD patterns of high P-T samples and recovered samples were acquired at BL10XU, SPring-8. We measured the Raman spectra of the samples at high-P and room temperature and those recovered at an ambient condition. Diamond and MgSiO3 perovskite were observed at 70 GPa and temperatures above 1750 K. The high P-T XRD patterns showed the appearance of MgSiO3 perovskite at 50-60 GPa and around 2000 K. Our study revealed that magnesite could decarbonate to form diamond in cold slabs at the depths greater than 1800- km depth due to the above reactions in the MgCO3-SiO2 system.

  20. Biplane double-supported screw fixation (F-technique): a method of screw fixation at osteoporotic fractures of the femoral neck.

    PubMed

    Filipov, Orlin

    2011-10-01

    The present work introduces a method of screw fixation of femoral neck fractures in the presence of osteoporosis, according to an original concept of the establishment of two supporting points for the implants and their biplane positioning in the femoral neck and head. The provision of two steady supporting points for the implants and the highly increased (obtuse) angle at which they are positioned allow the body weight to be transferred successfully from the head fragment onto the diaphysis, thanks to the strength of the screws, with the patient's bone quality being of least importance. The position of the screws allows them to slide under stress with a minimal risk of displacement. The method was developed in search of a solution for those patients for whom primary arthroplasty is contraindicated. The method has been analysed in relation to biomechanics and statics. For the first time, a new function is applied to a screw fixation-the implant is presented as a simple beam with an overhanging end.

  1. Freeze-fracture cytochemistry: thin sections of cells and tissues after labeling of fractures faces.

    PubMed

    da Silva, P P; Parkison, C; Dwyer, N

    1981-08-01

    Experimental details of a new method for the cytochemical characterization of the membrane faces and cytoplasm produced by freeze-fracture of isolated cells and tissues are presented. This new method-"fracture-label"-involves grinding of frozen samples immersed in liquid nitrogen, thawing, cytochemical labeling of the fractured faces, and processing for thin section electron microscopy. Cationized ferritin (at pH. 7.5 and 4.0), colloidal iron, as well as concanavalin A are used to label the fractures faces of leukocytes and Hela cells embedded in a cross-linked matrix of bovine serum albumin and of liver and spleen tissues. Our results show the presence of numerous anionic binding sites on the fracture faces of all plasma and cytoplasmic membranes, and of concanavalin A binding sites preferentially associated to the exoplasmic fracture faces of plasma and nuclear envelope membranes. A proportion of the anionic sites appears to be revealed by, or during, the freeze-fracture process. Colloidal iron labeling also shows preferential association with the chromatin areas of cross-fractured nuclei. The results show that "fracture-label", i.e., the combined application of freeze-fracture and cytochemical labeling techniques, can be used to study the surface chemistry of the fractures faces of biological membranes as well as of cross-fractured cytoplasm. PMID:7276536

  2. Middle Miocene near trench volcanism in northern Colombia: A record of slab tearing due to the simultaneous subduction of the Caribbean Plate under South and Central America?

    NASA Astrophysics Data System (ADS)

    Lara, M.; Cardona, A.; Monsalve, G.; Yarce, J.; Montes, C.; Valencia, V.; Weber, M.; De La Parra, F.; Espitia, D.; López-Martínez, M.

    2013-08-01

    Field, geochemical, geochronological, biostratigraphical and sedimentary provenance results of basaltic and associated sediments northern Colombia reveal the existence of Middle Miocene (13-14 Ma) mafic volcanism within a continental margin setting usually considered as amagmatic. This basaltic volcanism is characterized by relatively high Al2O3 and Na2O values (>15%), a High-K calc-alkaline affinity, large ion lithophile enrichment and associated Nb, Ta and Ti negative anomalies which resemble High Al basalts formed by low degree of asthenospheric melting at shallow depths mixed with some additional slab input. The presence of pre-Cretaceous detrital zircons, tourmaline and rutile as well as biostratigraphic results suggest that the host sedimentary rocks were deposited in a platform setting within the South American margin. New results of P-wave residuals from northern Colombia reinforce the view of a Caribbean slab subducting under the South American margin. The absence of a mantle wedge, the upper plate setting, and proximity of this magmatism to the trench, together with geodynamic constraints suggest that the subducted Caribbean oceanic plate was fractured and a slab tear was formed within the oceanic plate. Oceanic plate fracturing is related to the splitting of the subducting Caribbean Plate due to simultaneous subduction under the Panama-Choco block and northwestern South America, and the fast overthrusting of the later onto the Caribbean oceanic plate.

  3. Identifying Fracture Types and Relative Ages Using Fluid Inclusion Stratigraphy

    SciTech Connect

    Dilley, Lorie M.; Norman, David; Owens, Lara

    2008-06-30

    Enhanced Geothermal Systems (EGS) are designed to recover heat from the subsurface by mechanically creating fractures in subsurface rocks. Understanding the life cycle of a fracture in a geothermal system is fundamental to the development of techniques for creating fractures. Recognizing the stage of a fracture, whether it is currently open and transmitting fluids; if it recently has closed; or if it is an ancient fracture would assist in targeting areas for further fracture stimulation. Identifying dense fracture areas as well as large open fractures from small fracture systems will also assist in fracture stimulation selection. Geothermal systems are constantly generating fractures, and fluids and gases passing through rocks in these systems leave small fluid and gas samples trapped in healed microfractures. Fluid inclusions trapped in minerals as the fractures heal are characteristic of the fluids that formed them, and this signature can be seen in fluid inclusion gas analysis. Our hypothesis is that fractures over their life cycle have different chemical signatures that we can see in fluid inclusion gas analysis and by using the new method of fluid inclusion stratigraphy (FIS) the different stages of fractures, along with an estimate of fracture size can be identified during the well drilling process. We have shown with this study that it is possible to identify fracture locations using FIS and that different fractures have different chemical signatures however that signature is somewhat dependent upon rock type. Open, active fractures correlate with increase concentrations of CO2, N2, Ar, and to a lesser extent H2O. These fractures would be targets for further enhancement. The usefulness of this method is that it is low cost alternative to current well logging techniques and can be done as a well is being drilled.

  4. Radial head fracture - aftercare

    MedlinePlus

    Elbow fracture - radial head - aftercare ... to 2 weeks. If you have a small fracture and your bones did not move around much, ... to see a bone doctor (orthopedic surgeon). Some fractures require surgery to: Insert pins and plates to ...

  5. Effects of edge restraint on slab behavior. Final report

    SciTech Connect

    Guice, L.K.

    1986-02-01

    This study was performed in conjunction with a Federal Emergency Management Agency program to plan, design, and construct keyworker blast shelters which would be used in high-risk areas of the country during and after a nuclear attack. The shelters considered in this study were box-type structures in which damage is much more likely to occur in the roof slab than in the walls or floor. In this part of the program, the effect of edge restraint on slab behavior was investigated. The primary objective was to determine the effects of partial rotational restraint on slab strength, ductility, and mechanism of failure. Sixteen one-way, reinforced concrete plate elements were tested in a reaction structure under uniform static water pressure.

  6. Abrupt tectonics and rapid slab detachment with grain damage.

    PubMed

    Bercovici, David; Schubert, Gerald; Ricard, Yanick

    2015-02-01

    A simple model for necking and detachment of subducting slabs is developed to include the coupling between grain-sensitive rheology and grain-size evolution with damage. Necking is triggered by thickened buoyant crust entrained into a subduction zone, in which case grain damage accelerates necking and allows for relatively rapid slab detachment, i.e., within 1 My, depending on the size of the crustal plug. Thick continental crustal plugs can cause rapid necking while smaller plugs characteristic of ocean plateaux cause slower necking; oceanic lithosphere with normal or slightly thickened crust subducts without necking. The model potentially explains how large plateaux or continental crust drawn into subduction zones can cause slab loss and rapid changes in plate motion and/or induce abrupt continental rebound. PMID:25605890

  7. Role of Hydrogen in stagnant slabs and big mantle wedge

    NASA Astrophysics Data System (ADS)

    Ohtani, E.; Zhao, D.

    2008-12-01

    Recent seismic tomography data imply that subducting slabs are stagnant at some regions such as beneath Japan and Northeast China [1, 2]. The stagnant slab can have an important effect on the overlying transition zone and upper mantle. A big mantle wedge (BMW) model has been proposed by Zhao [2], in which the stagnant slab in the transition zone could play an essential role in the intra-plate volcanic activities overlying the slab. Water released by the stagnant slab could be important for such igneous activities, such as Mt. Changbai in Northeast China. In cold subducting slabs, several hydrous minerals together with nominally anhydrous minerals accommodate OH and transport water into the transition zone [3]. The effect of dehydration of the stagnant slab has been analyzed by Richard et al. [4]. They argued that warming of the stagnant slab due to heat conduction could play an important role for the slab dehydration, and local oversaturation could be achieved due to decrease of the water solubility in minerals with temperature, and fluid can be formed in the overlying transition zone. We determined the hydrogen diffusion in wadsleyite and ringwoodite under the transition zone conditions in order to clarify the deep processes of the stagnant slabs, and found that diffusion rates of hydrogen are comparable with that of olivine [5]. We also determined the dihedral angle of aqueous fluid between wadsleyite grains and majorite grains under the transition zone conditions. The dihedral angles are very small, around 20-40 degrees, indicating that the oversaturated fluids can move rapidly by the percolation mechanism in the transition zone. The fluids moved to the top of the 410 km discontinuity can generate heavy hydrous melts due to a larger depression of the wet solidus at the base of the upper mantle [6]. Gravitationally stable hydrous melts can be formed at the base of the upper mantle, which is consistent with seismological observations of the low velocity beneath

  8. Abrupt tectonics and rapid slab detachment with grain damage.

    PubMed

    Bercovici, David; Schubert, Gerald; Ricard, Yanick

    2015-02-01

    A simple model for necking and detachment of subducting slabs is developed to include the coupling between grain-sensitive rheology and grain-size evolution with damage. Necking is triggered by thickened buoyant crust entrained into a subduction zone, in which case grain damage accelerates necking and allows for relatively rapid slab detachment, i.e., within 1 My, depending on the size of the crustal plug. Thick continental crustal plugs can cause rapid necking while smaller plugs characteristic of ocean plateaux cause slower necking; oceanic lithosphere with normal or slightly thickened crust subducts without necking. The model potentially explains how large plateaux or continental crust drawn into subduction zones can cause slab loss and rapid changes in plate motion and/or induce abrupt continental rebound.

  9. Requalification analysis of a circular composite slab for seismic load

    SciTech Connect

    Srinivasan, M.G.; Kot, C.A.

    1992-11-01

    The circular roof slab of an existing facility was analyzed to requalify the structure for supporting a significant seismic load that it was not originally designed for. The slab has a clear span of 66 ft and consists of a 48 in thick reinforced concrete member and a steel liner plate. Besides a number of smaller penetrations, the slab contains two significant cutouts: a 9 ft square opening and a 3 ft dia hole. The issues that complicated the analysis of this non-typical structure, i.e., composite action and nonlinear stiffness of reinforced concrete (R. C.) sections, are discussed. It was possible to circumvent the difficulties by making conservative and simplifying assumptions. If codes incorporate guidelines on practical methods for dynamic analysis of R. C. structures, some of the unneeded conservatism could be eliminated in future designs.

  10. Dynamic triggering of deep earthquakes within a fossil slab

    NASA Astrophysics Data System (ADS)

    Cai, Chen; Wiens, Douglas A.

    2016-09-01

    The 9 November 2009 Mw 7.3 Fiji deep earthquake is the largest event in a region west of the Tonga slab defined by scattered seismicity and velocity anomalies. The main shock rupture was compact, but the aftershocks were distributed along a linear feature at distances of up to 126 km. The aftershocks and some background seismicity define a sharp northern boundary to the zone of outboard earthquakes, extending westward toward the Vitiaz deep earthquake cluster. The northern earthquake lineament is geometrically similar to tectonic reconstructions of the relict Vitiaz subduction zone at 8-10 Ma, suggesting the earthquakes are occurring in the final portion of the slab subducted at the now inactive Vitiaz trench. A Coulomb stress change calculation suggests many of the aftershocks were dynamically triggered. We propose that fossil slabs contain material that is too warm for earthquake nucleation but may be near the critical stress susceptible to dynamic triggering.

  11. Abrupt tectonics and rapid slab detachment with grain damage

    PubMed Central

    Bercovici, David; Schubert, Gerald; Ricard, Yanick

    2015-01-01

    A simple model for necking and detachment of subducting slabs is developed to include the coupling between grain-sensitive rheology and grain-size evolution with damage. Necking is triggered by thickened buoyant crust entrained into a subduction zone, in which case grain damage accelerates necking and allows for relatively rapid slab detachment, i.e., within 1 My, depending on the size of the crustal plug. Thick continental crustal plugs can cause rapid necking while smaller plugs characteristic of ocean plateaux cause slower necking; oceanic lithosphere with normal or slightly thickened crust subducts without necking. The model potentially explains how large plateaux or continental crust drawn into subduction zones can cause slab loss and rapid changes in plate motion and/or induce abrupt continental rebound. PMID:25605890

  12. Systematic effects induced by a flat isotropic dielectric slab.

    PubMed

    Macculi, Claudio; Zannoni, Mario; Peverini, Oscar Antonio; Carretti, Ettore; Tascone, Riccardo; Cortiglioni, Stefano

    2006-07-20

    The instrumental polarization induced by a flat isotropic dielectric slab in microwave frequencies is discussed. We find that, in spite of its isotropic nature, such a dielectric can produce spurious polarization either by transmitting incoming anisotropic diffuse radiation or emitting when it is thermally inhomogeneous. We present evaluations of instrumental polarization generated by materials usually adopted in radio astronomy, by using the Mueller matrix formalism. As an application, results for different slabs in front of a 32 GHz receiver are discussed. Such results are based on measurements of their complex dielectric constants. We evaluate that a 0.33 cm thick Teflon slab introduces negligible spurious polarization (<2.6 x 10(-5) in transmission and <6 x 10(-7) in emission), even minimizing the leakage (<10(-8) from Q to U Stokes parameters, and vice versa) and the depolarization (approximately 1.3 x 10(-3)).

  13. Slab detachment of subducted Indo-Australian plate beneath Sunda arc, Indonesia

    NASA Astrophysics Data System (ADS)

    Kundu, Bhaskar; Gahalaut, V. K.

    2011-04-01

    Necking, tearing, slab detachment and subsequently slab loss complicate the subduction zone processes and slab architecture. Based on evidences which include patterns of seismicity, seismic tomography and geochemistry of arc volcanoes, we have identified a horizontal slab tear in the subducted Indo-Australian slab beneath the Sunda arc. It strongly reflects on trench migration, and causes along-strike variations in vertical motion and geochemically distinct subduction-related arc magmatism. We also propose a model for the geodynamic evolution of slab detachment.

  14. Waveform modeling the deep slab beneath northernmost Nevada

    NASA Astrophysics Data System (ADS)

    Helmberger, D. V.; Sun, D.

    2011-12-01

    The interactions between subducted slab and transition zone are crucial issues in dynamic modeling. Previous mantle convection studies have shown that various viscosity structures can result in various slab shape, width, and edge sharpness. Recent tomographic images based on USArray data reveals strong multi-scale heterogeneous upper mantle beneath western US. Among those features, a slab-like fast anomaly extends from 300 to 600 km depth below Nevada and western Utah, which was suggested as a segmented chunk of the Farallon slab. But we still missing key information about the details of this structure and whether this structure flatten outs in the transition zone, where various tomographic models display inconsistent images. The study of multipathing and waveform broadening around sharp features have been proved a efficient way to study such features. Here, we use both P and S waveform data from High Lava Plains seismic experiments and USArray to produce a detailed image. If we amplify the Schmandt and Humphreys [2010] 's S-wave tomography model by 1.5, we can produce excellent travel-time fits. But the waveform distortions are not as strong as those observed in data for events coming from the southeast, which suggest a much sharper anomaly. The waveform broadening features are not observed for events arriving from northwestern. By fitting the SH waveform data, we suggest that this slab-like structure dips ~35° to the southeast, extending to a depth near 660 km with a velocity increase of about 5 per cent. To generate corresponding P model, we adapt the SH wave model and scale the model using a suite of R (=dlnVs/dlnVp) values. We find that synthetics from the model with R ≈ 2 can fit the observed data, which confirms the segmented slab interpretation of this high velocity anomaly.

  15. Fractured Surface

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03084 Fractured Surface

    These fractures and graben are part of Gordii Fossae, a large region that has undergone stresses which have cracked the surface.

    Image information: VIS instrument. Latitude 16.6S, Longitude 234.3E. 18 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  16. Fracture of the hook of the hamate.

    PubMed

    Stark, H H; Chao, E K; Zemel, N P; Rickard, T A; Ashworth, C R

    1989-09-01

    We removed the fracture fragment from fifty-nine patients who had an isolated fracture of the hook of the hamate. Preoperatively, all had complained of pain and tenderness on the ulnar side of the palm or on the dorsal ulnar aspect of the wrist. Most fractures were thought to have occurred while the patient was swinging a racquet, golf club, or baseball bat. Some fractures were caused by striking the palm on a solid object, by falling on the palm, or by a crush injury to the hand. Most of the fractures were diagnosed conclusively on a carpal tunnel roentgenogram or on a special oblique roentgenogram of the wrist supinated. We now believe that computed axial tomography is the best imaging technique for demonstrating this fracture. Except for two patients who had a crush injury, all of the patients returned to their regular occupational and athletic pursuits. There were no surgical complications.

  17. Radial head fractures--an update.

    PubMed

    Pike, Jeffrey M; Athwal, George S; Faber, Kenneth J; King, Graham J W

    2009-03-01

    Radial head fractures are the most common fractures occurring around the elbow. Although radial head fractures can occur in isolation, associated fractures and ligament injuries are common. Assembling the clinical presentation, physical examination, and imaging into an effective treatment plan can be challenging. The characteristics of the radial head fracture influence the technique used to optimize the outcome. Fragment number, displacement, impaction, and bone quality are considered when deciding between early motion, fragment excision, and radial head excision, repair, or replacement. Isolated, minimally displaced fractures without evidence of mechanical block can be treated nonsurgically with early active range of motion (ROM). Partial, displaced radial head fractures without evidence of mechanical block can be treated either nonsurgically or with open reduction internal fixation (ORIF), as current evidence does not prove superiority of either strategy. For displaced fractures with greater than 3 fragments, radial head replacement is recommended. Radial head arthroplasty may be preferred over tenuous fracture fixation in the setting of associated ligament injuries when maintenance of joint stability could be compromised by ineffective fracture fixation. PMID:19258159

  18. Technical considerations for surgical intervention of Jones fractures.

    PubMed

    Mendicino, Robert W; Hentges, Matthew J; Mendicino, Michael R; Catanzariti, Alan R

    2013-01-01

    Jones fractures are a common injury treated by foot and ankle surgeons. Surgical intervention is recommended because of the high rate of delayed union, nonunion, and repeat fracture, when treated conservatively. Percutaneous intramedullary screw fixation is commonly used in the treatment of these fractures. We present techniques that can increase the surgical efficiency and decrease the complications associated with percutaneous delivery of internal fixation.

  19. Expansion of a cold non-neutral plasma slab

    SciTech Connect

    Karimov, A. R.; Yu, M. Y.; Stenflo, L.

    2014-12-15

    Expansion of the ion and electron fronts of a cold non-neutral plasma slab with a quasi-neutral core bounded by layers containing only ions is investigated analytically and exact solutions are obtained. It is found that on average, the plasma expansion time scales linearly with the initial inverse ion plasma frequency as well as the degree of charge imbalance, and no expansion occurs if the cold plasma slab is stationary and overall neutral. However, in both cases, there can exist prominent oscillations on the electron front.

  20. Seismic Behaviour of Masonry Vault-Slab Structures

    SciTech Connect

    Chesi, Claudio; Butti, Ferdinando; Ferrari, Marco

    2008-07-08

    Spandrel walls typically play a structural role in masonry buildings, transferring load from a slab to the supporting vault. Some indications are given in the literature on the behaviour of spandrels under the effect of vertical loads, but little attention is given to the effect coming from lateral forces acting on the building. An opportunity to investigate this problem has come from the need of analyzing a monumental building which was damaged by the Nov. 24, 2004 Val Sabbia earthquake in the north of Italy. The finite element model set up for the analysis of the vault-spandrel-slab system is presented and the structural role resulting for the spandrels is discussed.

  1. Investigating the Farallon Slab with Probabilistic Traveltime Tomography

    NASA Astrophysics Data System (ADS)

    Burdick, S.; Lekic, V.

    2015-12-01

    Subduction of the Farallon Plate beneath North America played a key role in its tectonic development. Seismic constraints on the subducted remnants of the Farallon slab provide evidence needed to better understand the polarity and timing of subduction, the structure of the plate, and its relation to tectonic events like the uplift of the Rocky Mountains. Over the course of its deployment, the USArray Transportable Array (TA) has offered ideal data coverage for investigating the Farallon and related slabs in the upper mantle using seismic tomography and converted wave imaging. With its arrival in the east, data from the TA provides the crossing paths necessary to image the upper reaches of the oldest parts of the plate at mid-mantle depths. We perform a global tomographic inversion using the latest P-wave traveltime picks from TA combined with global catalogue data. While the new velocity model resolves upper mantle slab structure at unprecedented detail in the east, a quantitative grasp of model uncertainty is needed to reliably relate velocity variations to the thermal and mechanical properties of the slabs. In order to quantify the uncertainty of our tomographic model, we employ Transdimensional Hierarchical Bayesian (THB) inversion. THB tomography uses Markov chain Monte Carlo to create an ensemble of velocity models that can be analyzed to statistically infer the best-fit velocities, their uncertainties, and tradeoffs. We present and discuss various representations of uncertainty quantified by THB tomography—error bars, model covariance, multimodal distributions of velocity values—and demonstrate its importance for furthering our understanding of the slab fragments beneath North America. We illustrate how we are able to distinguish between spurious slab fragments from those required by the data. By examining bimodal velocity distributions, we put error bars on the spatial extent of the slabs that can then be analyzed using thermal diffusion modeling. By

  2. Links between fluid circulation, temperature, and metamorphism in subducting slabs

    USGS Publications Warehouse

    Spinelli, G.A.; Wang, K.

    2009-01-01

    The location and timing of metamorphic reactions in subducting lithosph??re are influenced by thermal effects of fluid circulation in the ocean crust aquifer. Fluid circulation in subducting crust extracts heat from the Nankai subduction zone, causing the crust to pass through cooler metamorphic faci??s than if no fluid circulation occurs. This fluid circulation shifts the basalt-to-eclogite transition and the associated slab dehydration 14 km deeper (35 km farther landward) than would be predicted with no fluid flow. For most subduction zones, hydrothermal cooling of the subducting slab will delay eclogitization relative to estimates made without considering fluid circulation. Copyright 2009 by the American Geophysical Union.

  3. Slab Driven Mantle Deformation and Plate-Mantle Decoupling

    NASA Astrophysics Data System (ADS)

    Jadamec, M. A.; MacDougall, J.; Fischer, K. M.

    2015-12-01

    Observations of shear wave splitting derived from local sources in subduction zones suggest viscous flow in the mantle wedge is commonly non-parallel to both the subducting plate velocity vector and the motion of the overriding plate. However, far from the subduction zone trench, observations indicate the fast axis of shear wave splitting tends to align with the velocity vector of the surface plates. Similarly, previous 3D geodynamic models show the slab can drive local decoupling of the mantle and surface plates, in both direction and speed. This suggests that there is some distance from the trench over which there is significant decoupling of the mantle flow from surface plate motion, and that this decoupling zone then decays with continued distance from the trench, resulting in far-field plate-mantle coupling. Here we present results from geodynamic models of subduction coupled with calculations of olivine fabric deformation and synthetic splitting to 1) examine the influence of slab strength, slab dip, and non-Newtonian viscosity on the deformation fabric in the mantle wedge and subslab mantle and 2) quantify the spatial extent and intensity of this slab driven decoupling zone. We compare the deformation fabric in a 2D corner flow solution with varying dip to that of a 2D free subduction model with varying initial dip and slab strength. The results show that using an experimentally derived flow law to define viscosity (both diffusion creep and dislocation creep deformation mechanisms) has a first order effect on the viscosity structure and flow velocity in the upper mantle. The free subduction models using the composite viscosity formulation produce a zone of subduction induced mantle weakening that results in reduced viscous support of the slab and lateral variability in coupling of the mantle to the base of the surface plates. The maximum yield stress, which places an upper bound on the slab strength, can also have a significant impact on the viscosity

  4. Multiwell fracturing experiments. [Nitrogen foam fracture treatment

    SciTech Connect

    Warpinski, N.

    1985-01-01

    The objective of the Multiwell fracturing experiments is to test and develop the technology for the efficient stimulation of tight, lenticular gas sands. This requires basic understanding of: (1) fracture behavior and geometry in this complex lithologic environment, and (2) subsequent production into the created fracture. The intricate interplay of the hydraulic fracture with the lens geometry, the internal reservoir characteristics (fractures, reservoir breaks, etc.), the in situ stresses, and the mechanical defects (fracture, bedding, etc.) need to be defined in order to develop a successful stimulation program. The stimulation phase of the Multiwell Experiment is concerned with: (1) determining important rock/reservoir properties that influence or control fracture geometry and behavior, (2) designing fracture treatments to achieve a desired size and objectives, and (3) conducting post-treatment analyses to evaluate the effectiveness of the treatment. Background statement, project description, results and evaluation of future plans are presented. 5 refs., 2 figs., 2 tabs.

  5. Flow upscaling in propped fracture

    NASA Astrophysics Data System (ADS)

    Jasinski, Lukasz; Dabrowski, Marcin

    2016-04-01

    Proppants in combination with hydraulic fracturing are widely used to maintain the production of oil or gas from low permeability formations (i.e. shale rocks). There are also examples of proppants use in geothermal reservoirs. Flow patterns in propped fracture control transport processes and give information about fracture/matrix exchange surface. Our main motivation is to understand flow behavior in such structures using direct numerical simulations and to find a good upscaling technique to be able to investigate models on reservoir scale. We study fracture made of two parallel plane walls, where void space between them is filled with partial monolayer of proppant. As the fracture is affected by closing pressure, the proppant grains are squeezed between two opposite fracture walls which can change the grain shapes or embed the grains into impermeable rock matrix. To take this effect into account and simplify the geometry, the grains are approximated as cylinders. Imposed macroscopic pressure gradient invokes flow in such medium. As the flow is considered in the low Reynolds number regime, a stationary velocity flow field is obtained by solving the Stokes equations in 3D by means of finite element method. Void space between the grains is accurately discretized by using tetrahedral mesh. To reduce computational effort, the Stokes equation is reduced over the fracture aperture to 2D Stokes-Brinkman equation, which is further numerically solved and compared against numerical solution in 3D. Systematic flow calculations using 2D Stokes-Brinkman equation are performed for periodic domain and no slip boundary condition on the grain surface. Results are discussed in terms of effective properties as a function of geometrical parameters of the medium, such as proppant packing fraction and proppant grain diameter to fracture aperture ratio.

  6. Control of slab width on subduction-induced upper mantle flow and associated upwellings: Insights from analog models

    NASA Astrophysics Data System (ADS)

    Strak, Vincent; Schellart, Wouter P.

    2016-06-01

    The impact of slab width W (i.e., trench-parallel extent) on subduction-induced upper mantle flow remains uncertain. We present a series of free subduction analog models where W was systematically varied to upscaled values of 250-3600 km to investigate its effect on subducting plate kinematics and upper mantle return flow around the lateral slab edges. We particularly focused on the upwelling component of mantle flow, which might promote decompression melting and could thereby produce intraplate volcanism. The models show that W has a strong control on trench curvature and on the trench retreat, subducting plate, and subduction velocities, generally in good agreement with previous modeling studies. Upper mantle flow velocity maps produced by means of a stereoscopic particle image velocimetry technique indicate that the magnitude of the subduction-induced mantle flow around the lateral slab edges correlates positively with the product of W and trench retreat velocity. For all models an important upwelling component is always produced close to the lateral slab edges, with higher magnitudes for wider slabs. The trench-parallel lateral extent of this upwelling component is the same irrespective of W, but its maximum magnitude gets located closer to the subducting plate in the trench-normal direction and it is more focused when W increases. For W ≤ 2000 km the upwelling occurs laterally (in the trench-parallel direction) next to the subslab domain and the mantle wedge domain, while for W ≥ 2000 km it is located only next to the subslab domain and focuses closer to the trench tip, because of stronger poloidal flow in the mantle wedge extending laterally.

  7. Complications in operative fixation of calcaneal fractures

    PubMed Central

    Li, Ying; Bao, Rong-Hua; Jiang, Zhi-Qiang; Wu, Huo-Yan

    2016-01-01

    Objective: The purpose of this study focused on a number of factors that have been implicated in calcaneal complications and find the incidence of wound complications. Methods: This was a retrospective study. A total of 162 patients (176 feet) who underwent calcaneal fractures between 2007 and 2012 were included. The patient’s personal details, age, time from injury to surgery, cause of injury, type of fracture, operative details, operating and tourniquet times were collected from hospital computers and paper records. Evidence of complications including wound infection, wound necrosis, pain, malunion, nonunion, impingement, loss of fixation, ect were studied. Results: Forty-seven of one hundred and seventy-six fractures (26.704%) had complications, wound infection was noted in seven fractures (3.977%), twelve fractures developed necrosis (6.818%), 14 fractures (7.955%) developed pain. Malunion was found in five fractures (2.841%), nonunion in two fractures (1.136%) and loss of fixation in four fractures (2.272%). Three neurologic injury was also seen in our study (1.705%). Operating time, time from injury to surgery and type of fracture had some association with complications in operative fixation of calcaneal fractures, which showed a statistically significant improvement (P=0.000, 0.031, 0.020, respectively), but there were no evidence that age and tourniquet time affect the incidence of complication after calcaneal fracture surgery (P=0.119, 0.682, respectively). Conclusions: Despite developments in the surgical treatment of calcaneal fracture, wound complications still remain inevitable. Advanced imaging techniques, less invasive surgical procedures, wealth of anatomical knowledge, surgical experience and better postoperative care should be ensured.

  8. Complications in operative fixation of calcaneal fractures

    PubMed Central

    Li, Ying; Bao, Rong-Hua; Jiang, Zhi-Qiang; Wu, Huo-Yan

    2016-01-01

    Objective: The purpose of this study focused on a number of factors that have been implicated in calcaneal complications and find the incidence of wound complications. Methods: This was a retrospective study. A total of 162 patients (176 feet) who underwent calcaneal fractures between 2007 and 2012 were included. The patient’s personal details, age, time from injury to surgery, cause of injury, type of fracture, operative details, operating and tourniquet times were collected from hospital computers and paper records. Evidence of complications including wound infection, wound necrosis, pain, malunion, nonunion, impingement, loss of fixation, ect were studied. Results: Forty-seven of one hundred and seventy-six fractures (26.704%) had complications, wound infection was noted in seven fractures (3.977%), twelve fractures developed necrosis (6.818%), 14 fractures (7.955%) developed pain. Malunion was found in five fractures (2.841%), nonunion in two fractures (1.136%) and loss of fixation in four fractures (2.272%). Three neurologic injury was also seen in our study (1.705%). Operating time, time from injury to surgery and type of fracture had some association with complications in operative fixation of calcaneal fractures, which showed a statistically significant improvement (P=0.000, 0.031, 0.020, respectively), but there were no evidence that age and tourniquet time affect the incidence of complication after calcaneal fracture surgery (P=0.119, 0.682, respectively). Conclusions: Despite developments in the surgical treatment of calcaneal fracture, wound complications still remain inevitable. Advanced imaging techniques, less invasive surgical procedures, wealth of anatomical knowledge, surgical experience and better postoperative care should be ensured. PMID:27648028

  9. Coupled waves at fracture intersections

    NASA Astrophysics Data System (ADS)

    Abell, B.; Pyrak-Nolte, L. J.

    2014-12-01

    Fracture intersections play a crucial role in the hydraulic connectivity of flow paths in rock, yet no current techniques exist for characterizing the conditions of an intersection. We demonstrate experimentally and theoretically that elastic waves propagated along fracture intersections are affected by the amount of contact among the blocks forming an intersection. Surface fractures and fracture intersections can be viewed as wedges (corners) coupled through the points of contact along the intersection. An eigenvalue secular equation was derived using displacement discontinuity theory along with the solution for a wedge wave. The velocity and motion of intersection waves are a function of the frequency, material impedance, and specific stiffness of the intersection. For an intersection, several modes are present that represent the coupling between different sets of the wedges and exhibit wave speeds between a single wedge mode and the bulk S wave. A surface fracture supports only one mode of propagation with speeds that range from the single wedge wave to that of the Rayleigh wave. Experiments were performed on intersections made from two or four aluminum samples (0.29 x 0.076 x 0.076 m) to detect intersection waves. Measurements were made under uniaxial and biaxial loading conditions to change the contact area along an intersection. At low loads both the surface fracture and intersection excite wedge waves because the stress between the wedges was not sufficiently high to couple the wedges. As the external load was increased, the wave coupled the wedges and propagated as a Rayleigh wave for the surface fracture, or as a bulk S wave for the intersection. These results indicate that the specific stiffness of the fracture intersection can be estimated based upon the velocity of the wave propagating along the intersection or surface fracture. Using this estimation the flow path(s) along or through the fracture intersection or surface fracture can be characterized and

  10. Proximal fifth metatarsal fractures.

    PubMed

    Ramponi, Denise R

    2013-01-01

    The most common fracture of the foot is a fracture of the proximal fifth metatarsal. In general, there are 3 types of fractures involving the proximal fifth metatarsal area, including a proximal diaphyseal stress fracture, a Jones fracture, and an avulsion fracture of the tuberosity. Some fractures of the fifth metatarsal heal without difficulty, whereas some have the potential for nonunion or delayed healing. Each fracture has some variation in the anatomical location on the fifth metatarsal, the mechanism of injury, the radiographic findings, and the treatment plan. Avulsion fractures of the tuberosity often heal without difficulty, yet fractures distal to the area of insertion of the peroneus brevis tendon are prone to nonunion and delayed healing (). Differential diagnosis of a fifth metatarsal midfoot injury includes ankle sprains, midfoot sprains, plantar facial ruptures, peroneus tendon ruptures, and other foot fractures.

  11. [Sarmiento's method of conservative treatment of leg fractures].

    PubMed

    Dewijze, M; Pe, M; Tondeur, G

    1985-01-01

    The authors present a prospective series of 32 fractures of the tibia, treated by Sarmiento's technique. Consolidation of the fracture has been obtained in 3 to 4 months. Five open tibia fractures healed in 4 months. Functional recovery is complete in 90% of the cases. Two failures needed late surgical treatment (one centro-medullary nailing and one plate-fixation). These fractures are studied in detail. PMID:3984632

  12. Fracture-correlated lineaments at Great Bay, southeastern New Hampshire

    USGS Publications Warehouse

    Degnan, James R.; Clark, Stewart F.

    2002-01-01

    Analysis by remote-sensing techniques and observations of exposed bedrock structure were preliminary steps taken in a study to locate potential bedrock-fracture zones that may store and transmit ground water near Great Bay, N.H. To help correlate lineaments on the surface with fractures, structural measurements were made at exposed bedrock, largely along the shoreline of the bay, and analyzed to identify fracture trends and fracture characteristics. With these fracture data, lineament-filtering techniques, such as (1) buffer analysis around individual lineaments, (2) discrete-measurement analysis by domain, and (3) spacing-normalized analysis by domain, identified 'fracture-correlated lineaments.' Of the 927 lineaments identified in the study area (180 square kilometers), 406 (44 percent) were evaluated because they either were located within 305 meters of an outcrop with fracture data or intersected one of five 3,300-meter-square grid domain cells that encompassed the fracture data. Of the 406 lineaments, 190 (47 percent) are fracture correlated, although only 15 percent were correlated by more than one filtering technique. The large number of lineaments found in areas of thin glacial overburden and high densities of fractured outcrops suggests that filtering techniques are useful in these areas to selectively identify fracture-correlated lineaments. Fractures parallel to bedding in the Kittery Formation are open locally and often associated with vugs, with up to 1-centimeter aperture, and may provide appreciable secondary porosity in this rock unit. Discrete-measurement analysis by domain identified fracture-correlated lineaments with orientations parallel to these open and vug-filled fractures. Fracture-correlated lineaments related to closely spaced fractures were identified by the spacing-normalized analysis by domain. Analysis results may be used to indicate the potential bedrock pathways for ground-water-discharge points along the shoreline of Great Bay.

  13. Highly efficient diode-stack, end-pumped Nd:YAG slab laser with symmetrized beam quality.

    PubMed

    Liao, Y; Du, K; Falter, S; Zhang, J; Quade, M; Loosen, P; Poprawe, R

    1997-08-20

    An efficient high-power cw Nd:YAG slab laser, partially end pumped by diode-laser stacks, and a novel beam-shaping technique are reported. The optical efficiency amounted to 44 %, and the slope efficiency amounted to 55 %. Introducing an intracavity Brewster plate to polarize the laser beam, we obtained an optical efficiency of 35 % and a slope efficiency of 41 %. The output beam was rectangular and the beam quality asymmetric in two orthogonal directions. To equalize the beam quality, we introduced a step-mirror beam-shaping technique. The beam-shaping technique and the results obtained are discussed.

  14. Approach for computing 1D fracture density: application to fracture corridor characterization

    NASA Astrophysics Data System (ADS)

    Viseur, Sophie; Chatelée, Sebastien; Akriche, Clement; Lamarche, Juliette

    2016-04-01

    Fracture density is an important parameter for characterizing fractured reservoirs. Many stochastic simulation algorithms that generate fracture networks indeed rely on the determination of a fracture density on volumes (P30) to populate the reservoir zones with individual fracture surfaces. However, only 1D fracture density (P10) are available from subsurface data and it is then important to be able to accurately estimate this entity. In this paper, a novel approach is proposed to estimate fracture density from scan-line or well data. This method relies on regression, hypothesis testing and clustering techniques. The objective of the proposed approach is to highlight zones where fracture density are statistically very different or similar. This technique has been applied on both synthetic and real case studies. These studies concern fracture corridors, which are particular tectonic features that are generally difficult to characterize from subsurface data. These tectonic features are still not well known and studies must be conducted to better understand their internal spatial organization and variability. The presented synthetic cases aim at showing the ability of the approach to extract known features. The real case study illustrates how this approach allows the internal spatial organization of fracture corridors to be characterized.

  15. Transition from slab to slabless: Results from the 1993 Mendocino triple junction seismic experiment

    USGS Publications Warehouse

    Beaudoin, B.C.; Godfrey, N.J.; Klemperer, S.L.; Lendl, C.; Trehu, A.M.; Henstock, T.J.; Levander, A.; Holl, J.E.; Meltzer, A.S.; Luetgert, J.H.; Mooney, W.D.

    1996-01-01

    Three seismic refraction-reflection profiles, part of the Mendocino triple junction seismic experiment, allow us to compare and contrast crust and upper mantle of the North American margin before and after it is modified by passage of the Mendocino triple junction. Upper crustal velocity models reveal an asymmetric Great Valley basin overlying Sierran or ophiolitic rocks at the latitude of Fort Bragg, California, and overlying Sierran or Klamath rocks near Redding, California. In addition, the upper crustal velocity structure indicates that Franciscan rocks underlie the Klamath terrane east of Eureka, California. The Franciscan complex is, on average, laterally homogeneous and is thickest in the triple junction region. North of the triple junction, the Gorda slab can be traced 150 km inboard from the Cascadia subduction zone. South of the triple junction, strong precritical reflections indicate partial melt and/or metamorphic fluids at the base of the crust or in the upper mantle. Breaks in these reflections are correlated with the Maacama and Bartlett Springs faults, suggesting that these faults extend at least to the mantle. We interpret our data to indicate tectonic thickening of the Franciscan complex in response to passage of the Mendocino triple junction and an associated thinning of these rocks south of the triple junction due to assimilation into melt triggered by upwelling asthenosphere. The region of thickened Franciscan complex overlies a zone of increased scattering, intrinsic attenuation, or both, resulting from mechanical mixing of lithologies and/or partial melt beneath the onshore projection of the Mendocino fracture zone. Our data reveal that we have crossed the southern edge of the Gorda slab and that this edge and/or the overlying North American crust may have fragmented because of the change in stress presented by the edge.

  16. Effect of isolated fractures on accelerated flow in unsaturated porous rock

    USGS Publications Warehouse

    Su, G.W.; Nimmo, J.R.; Dragila, M.I.

    2003-01-01

    Fractures that begin and end in the unsaturated zone, or isolated fractures, have been ignored in previous studies because they were generally assumed to behave as capillary barriers and remain nonconductive. We conducted a series of experiments using Berea sandstone samples to examine the physical mechanisms controlling flow in a rock containing a single isolated fracture. The input fluxes and fracture orientation were varied in these experiments. Visualization experiments using dyed water in a thin vertical slab of rock were conducted to identify flow mechanisms occurring due to the presence of the isolated fracture. Two mechanisms occurred: (1) localized flow through the rock matrix in the vicinity of the isolated fracture and (2) pooling of water at the bottom of the fracture, indicating the occurrence of film flow along the isolated fracture wall. These mechanisms were observed at fracture angles of 20 and 60 degrees from the horizontal, but not at 90 degrees. Pooling along the bottom of the fracture was observed over a wider range of input fluxes for low-angled isolated fractures compared to high-angled ones. Measurements of matrix water pressures in the samples with the 20 and 60 degree fractures also demonstrated that preferential flow occurred through the matrix in the fracture vicinity, where higher pressures occurred in the regions where faster flow was observed in the visualization experiments. The pooling length at the terminus of a 20 degree isolated fracture was measured as a function of input flux. Calculations of the film flow rate along the fracture were made using these measurements and indicated that up to 22% of the flow occurred as film flow. These experiments, apparently the first to consider isolated fractures, demonstrate that such features can accelerate flow through the unsaturated zone and should be considered when developing conceptual models.

  17. Imaging the slab-continent interface beneath Washington with spectral ambient noise tomography

    NASA Astrophysics Data System (ADS)

    Calkins, J. A.; Abers, G. A.; Ekstrom, G.; Creager, K. C.; Rondenay, S.

    2009-12-01

    The subduction interface beneath Western Washington hosts one of the first recognized and most reliably episodic zones of tremor and associated slow slip discovered at any subduction zone on earth, but produces very few thrust zone earthquakes. The thermal and petrologic conditions that contribute to this particular behavior along the Cascadia megathrust have been the subject of intense geophysical study in recent years, however interpretations of seismic data have been limited by the lack of information on absolute shear velocities in the crust and upper mantle of the overriding North American plate. We present the first high-resolution 3-d shear velocity images of the shallow western Washington lithosphere, obtained using a novel spectral technique for extracting phase velocities directly from cross-correlated ambient noise. Our technique allows us to resolve shear velocities at station offsets significantly (4-5x) shorter than those allowable using the traditional approach to ambient noise tomography, increasing the number of useable interstation paths by > 58% in the 4-30 second range. Our tomographic images show a distinct zone of low shear velocity (3.0-3.3 km/sec) in the mid to lower continental crust, directly above the portion of the slab expected to be undergoing dehydration reactions. This low velocity zone, which is more exaggerated beneath the Olympic peninsula than further to the south, also corresponds with the region of most intense episodic tremor and slip. Comparison with published P wave velocity data indicates that Vp/Vs ratios in this region are greater than 1.9, suggesting high pore fluid pressures. Beneath the forearc, where the slab descends below ~45 km depth, the mid crust hosts bodies of high shear velocity (>4.0 km/sec) rocks, possibly owing to accreted terrane composition or arc magma fractionation. Further east, the heterogeneous sub-arc crust has shear velocities more typical of intermediate continental crust, in the range of 3

  18. RAW COPPER SLABS USED IN CASTING OPERATIONS AT BUFFALO PLANT ...

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

    RAW COPPER SLABS USED IN CASTING OPERATIONS AT BUFFALO PLANT OF AMERICAN BRASS COMPANY. MATERIALS STORAGE FOR THE CAST SHOP NOW OCCUPIES A PORTION OF THE ORIGINAL BRASS MILL BUILT BY THE BUFFALO COPPER AND BRASS ROLLING MILL IN 1906-07 AND EXPANDED IN 1911. - American Brass Foundry, 70 Sayre Street, Buffalo, Erie County, NY

  19. Topological optical Bloch oscillations in a deformed slab waveguide.

    PubMed

    Longhi, Stefano

    2007-09-15

    Spatial Bloch oscillations of light waves of purely topological origin are theoretically shown to exist in weakly deformed slab waveguides. As the optical rays trapped in the deformed waveguide can roll freely, wave diffraction is strongly affected by the topology of the deformed surface, which can be tailored to simulate the effect of a tilted periodic refractive index.

  20. 8. WEST FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, FORMER ...

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

    8. WEST FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, FORMER DRAINAGE AREA IN THE DISTANCE, VIEW TOWARDS NORTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  1. 6. NO. 2 CONTINUOUS SLAB REHEATING FURNACE OF THE 160' ...

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

    6. NO. 2 CONTINUOUS SLAB REHEATING FURNACE OF THE 160' PLATE MILL. FURNACE SHOWING DURING DEMOLITION. C HOOK USED TO CHANGE ROLLS IS VISIBLE IN FRONT OF FURNACE. - U.S. Steel Homestead Works, 160" Plate Mill, Along Monongahela River, Homestead, Allegheny County, PA

  2. 52. SLABBING AND BLOOMING MILLS AND FOUNDRY (IN FOREGROUND), AS ...

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

    52. SLABBING AND BLOOMING MILLS AND FOUNDRY (IN FOREGROUND), AS SEEN FROM THE CLARK AVENUE BRIDGE. AT RIGHT, REAR, IS THE BASIC OXYGEN FURNACE. VIEW LOOKING NORTH. - Corrigan, McKinney Steel Company, 3100 East Forty-fifth Street, Cleveland, Cuyahoga County, OH

  3. Workmen and Crawler Crane pouring roof slab and parapet wall ...

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

    Workmen and Crawler Crane pouring roof slab and parapet wall of building - looking northwest. Taken Nov. 15, 1929. 14th Naval District Photo Collection Item No. 7165 - U.S. Naval Base, Pearl Harbor, Exterior Cranes, Waterfront Crane Track System, Pearl City, Honolulu County, HI

  4. Subduction of the Indian Lithospheric Slab Beneath Tibet

    NASA Astrophysics Data System (ADS)

    Zhou, H.; Murphy, M. A.

    2001-12-01

    In order to characterize the dynamics of continent-continent collisions, it is essential to define its present geometry and physical state. We report the results of a seismic tomography study of the Tibet-Himalayan collision zone, using a global data set, which indicates that the Indian lithospheric slab has been subducted subhorizontally beneath nearly the entire Tibetan plateau to depths of 165-260 km. Tibetan velocity structure is low in the crust and high in mantle lithosphere at depths between 75-120 km. An asthenospheric layer overlies the subducted Indian slab at depths between 120-165 km beneath the Tibetan plateau. There is a large low-velocity anomaly north of the Indus-Yalu suture zone between 85ºE and 93ºE that extends from the crust down to at least 310 km depth beneath the plateau. This low-velocity anomaly is indicative of mantle upwelling through a weakened zone of the subducted slab. The extent to which India has subducted beneath Tibet, as revealed by these seismic images, is comparable to estimates of crustal shortening across the Himalaya. Moreover, we hypothesize that the buoyancy due to heating of the subducted Indian slab and the existence of the asthenospheric layer contribute to the elevation and flatness of the Tibetan plateau.

  5. 18. FOURTH FLOOR BLDG. 28, RAISED CONCRETE SLAB FLOOR WITH ...

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

    18. FOURTH FLOOR BLDG. 28, RAISED CONCRETE SLAB FLOOR WITH BLOCKS AND PULLEYS OVERHEAD LOOKING NORTHEAST. - Fafnir Bearing Plant, Bounded on North side by Myrtle Street, on South side by Orange Street, on East side by Booth Street & on West side by Grove Street, New Britain, Hartford County, CT

  6. Photonic-crystal slab for terahertz-wave technology platform

    NASA Astrophysics Data System (ADS)

    Fujita, Masayuki

    2016-03-01

    Photonic crystals manipulate photons in a manner analogous to solid-state crystals, and are composed of a dielectric material with a periodic refractive index distribution. In particular, two-dimensional photonic-crystal slabs with high index contrasts (semiconductor/air) are promising for practical applications, owing to the strong optical confinement in simple, thin planar structures. This paper presents the recent progress on a silicon photonic-crystal slab as a technology platform in the terahertz-wave region, which is located between the radio and light wave regions (0.1-10 THz). Extremely low-loss (<0.1 dB/cm) terahertz waveguides based on the photonic-bandgap effect as well as dynamic control and modulation of a terahertz-wave transmission in a photonic-crystal slab by the effective interaction between photoexcited carriers and the terahertz-wave trapping due to the photonic band-edge effect are demonstrated. Terahertz photonic-crystal slabs hold the potential for developing ultralow-loss, compact terahertz components and integrated devices used in applications including wireless communication, spectroscopic sensing, and imaging.

  7. Tensor-guided fitting of subduction slab depths

    USGS Publications Warehouse

    Bazargani, Farhad; Hayes, Gavin P.

    2013-01-01

    Geophysical measurements are often acquired at scattered locations in space. Therefore, interpolating or fitting the sparsely sampled data as a uniform function of space (a procedure commonly known as gridding) is a ubiquitous problem in geophysics. Most gridding methods require a model of spatial correlation for data. This spatial correlation model can often be inferred from some sort of secondary information, which may also be sparsely sampled in space. In this paper, we present a new method to model the geometry of a subducting slab in which we use a data‐fitting approach to address the problem. Earthquakes and active‐source seismic surveys provide estimates of depths of subducting slabs but only at scattered locations. In addition to estimates of depths from earthquake locations, focal mechanisms of subduction zone earthquakes also provide estimates of the strikes of the subducting slab on which they occur. We use these spatially sparse strike samples and the Earth’s curved surface geometry to infer a model for spatial correlation that guides a blended neighbor interpolation of slab depths. We then modify the interpolation method to account for the uncertainties associated with the depth estimates.

  8. 62. SUPPORT CARRIAGE ASSEMBLY AT BASE OF VAL LAUNCHING SLAB ...

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

    62. SUPPORT CARRIAGE ASSEMBLY AT BASE OF VAL LAUNCHING SLAB AFTER TRANSFER FROM BARGE IN FOREGROUND, February, 11, 1948. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  9. 30. VAL LOOKING DOWN THE LAUNCHER SLAB STAIRS AT THE ...

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

    30. VAL LOOKING DOWN THE LAUNCHER SLAB STAIRS AT THE PROJECTILE LOADING CAR AND LOADING PLATFORM ADJACENT TO THE PROJECTILE LOADING DECK AND LAUNCHER BRIDGE. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  10. 63. VIEW LOOKING DOWN VAL LAUNCHING SLAB SHOWING DRIVE GEARS, ...

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

    63. VIEW LOOKING DOWN VAL LAUNCHING SLAB SHOWING DRIVE GEARS, CABLES, LAUNCHER RAILS, PROJECTILE CAR AND SUPPORT CARRIAGE, April 8, 1948. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  11. Enhancement of polarizabilities of cylinders with cylinder-slab resonances

    PubMed Central

    Xiao, Meng; Huang, Xueqin; Liu, H.; Chan, C. T.

    2015-01-01

    If an object is very small in size compared with the wavelength of light, it does not scatter light efficiently. It is hence difficult to detect a very small object with light. We show using analytic theory as well as full wave numerical calculation that the effective polarizability of a small cylinder can be greatly enhanced by coupling it with a superlens type metamaterial slab. This kind of enhancement is not due to the individual resonance effect of the metamaterial slab, nor due to that of the object, but is caused by a collective resonant mode between the cylinder and the slab. We show that this type of particle-slab resonance which makes a small two-dimensional object much “brighter” is actually closely related to the reverse effect known in the literature as “cloaking by anomalous resonance” which can make a small cylinder undetectable. We also show that the enhancement of polarizability can lead to strongly enhanced electromagnetic forces that can be attractive or repulsive, depending on the material properties of the cylinder. PMID:25641391

  12. Applications of acoustics in the measurement of coal slab thickness

    NASA Technical Reports Server (NTRS)

    Hadden, W. J., Jr.; Mills, J. M.; Pierce, A. D.

    1980-01-01

    The determination of the possibility of employing acoustic waves at ultrasonic frequencies for measurements of thicknesses of slabs of coal backed by shale is investigated. Fundamental information concerning the acoustical properties of coal, and the relationship between these properties and the structural and compositional parameters used to characterize coal samples was also sought. The testing device, which utilizes two matched transducers, is described.

  13. Emplacement of the Kodiak batholith and slab-window migration

    USGS Publications Warehouse

    Farris, David W.; Haeussler, P.; Friedman, R.; Paterson, S.R.; Saltus, R.W.; Ayuso, R.

    2006-01-01

    The Kodiak batholith is one of the largest, most elongate intrusive bodies in the forearc Sanak-Baranof plutonic belt located in southern Alaska. This belt is interpreted to have formed during the subduction of an oceanic spreading center and the associated migration of a slab window. Individual plutons of the Kodiak batholith track the location and evolution of the underlying slab window. Six U/Pb zircon ages from the axis of the batholith exhibit a northeastward-decreasing age progression of 59.2 ± 0.2 Ma at the southwest end to 58.4 ± 0.2 Ma at the northeast tip. The trench-parallel rate of age progression is within error of the average slab-window migration rate for the entire Sanak-Baranof belt (~19 cm/yr). Structural relationships, U/Pb ages, and a model of new gravity data indicate that magma from the Kodiak batholith ascended 5-10 km as a northeastward-younging series of 1-8-km-diameter viscoelastic diapirs. Individual plutons ascended by multiple emplacement mechanisms including downward flow, collapse of wall rock, stoping, and diking. Stokes flow xenolith calculations suggest ascent rates of 5-100 m/yr and an effective magmatic viscosity of 107-108 Pa s. Pre-existing structural or lithologic heterogeneities did not dominantly control the location of the main batholith. Instead, its location was determined by migration of the slab window at depth. 

  14. 11. VIEW OF PLACING STEEL FOR POURING OF FIRST SLABS ...

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

    11. VIEW OF PLACING STEEL FOR POURING OF FIRST SLABS OF SPILLWAY CHUTE FROM VICINITY OF WESTERN SIDE OF SPILLWAY APRON, FACING SOUTH. September 1928 - Cushman No. 1 Hydroelectric Power Plant, Spillway, North Fork of Skokomish River, 5 miles West of Hood Canal, Hoodsport, Mason County, WA

  15. DETAIL OF THE IMPRESSION IN THE CONCRETE SLAB OF THE ...

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

    DETAIL OF THE IMPRESSION IN THE CONCRETE SLAB OF THE SOUTH END OF THE ABOVE-GROUND PORTION. NOTE STEP DOWN TO THE STEEL PLATE IN BACKGROUND. VIEW FACING NORTH - U.S. Naval Base, Pearl Harbor, Ford Island 5-Inch Antiaircraft Battery, Battery Command Center, Ford Island, Pearl City, Honolulu County, HI

  16. DETAIL OF STEEL PLATE SET INTO THE CONCRETE SLAB OF ...

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

    DETAIL OF STEEL PLATE SET INTO THE CONCRETE SLAB OF THE NORTH END OF THE ABOVE-GROUND PORTION. VIEW FACING NORTH - U.S. Naval Base, Pearl Harbor, Ford Island 5-Inch Antiaircraft Battery, Battery Command Center, Ford Island, Pearl City, Honolulu County, HI

  17. Intramedullary nailing of acute femoral shaft fractures using manual traction without a fracture table.

    PubMed

    Karpos, P A; McFerran, M A; Johnson, K D

    1995-02-01

    Intramedullary (IM) nails were prospectively placed in 32 consecutive femoral shaft fractures without the use of a fracture table. All fractures were reduced using manual traction. Pathologic and nonacute fractures and those requiring a reconstruction nail were excluded. The results are compared with results of two prior study groups from this institution that underwent IM nailing with or without a fracture table using a femoral distractor. Ten patients had unstable spine or pelvis fractures. Four nailings followed exploratory laparotomy. Twelve patients underwent two or more procedures on the lower extremities under the same preparation and drape. Six fractures were open. Sixty-seven percent of results were anatomic, 27% had < 5 mm lengthening/shortening or < 5 degree varus/valgus, and 7% had > 5 mm lengthening/shortening or > 5 degree varus/valgus. Average operative time was 95 min. No complications occurred that were attributable to the technique. Compared with the prior study groups, no statistical difference in the fracture types or results was found. However, operative time was significantly less in the manual traction group (p < .05). We feel that this technique is a safe, simple, and effective alternative to using a fracture table. The technique is especially useful in the polytrauma patient, significantly decreasing anesthetic time.

  18. Influence of Natural Fractures Cohesive Properties on Geometry of Hydraulic Fracture Networks

    NASA Astrophysics Data System (ADS)

    Gonzalez-Chavez, M. A.; Dahi Taleghani, A.; Puyang, P.

    2014-12-01

    An integrated modeling methodology is proposed to analyze hydraulic fracturing jobs in the presence of the natural fracture network in the formation. A propagating hydraulic fracture may arrest, cross, or diverts into a preexisting natural crack depending on fracture properties of rock and magnitude and direction of principal rock stresses. Opening of natural fractures during fracturing treatment could define the effectiveness of the stimulation technique. Here, we present an integrated methodology initiated with lab scale fracturing properties using Double Cantilever Beam tests (DCB) to determine cohesive properties of rock and natural fractures. We used cohesive finite element models to reproduce laboratory results to verify the numerical model for the interaction of the hydraulic fracture and individual cemented natural fractures. Based on the initial investigations, we found out that distribution of pre-existing natural fractures could play a significant role in the final geometry of the induced fracture network; however in practice, there is not much information about the distribution of natural fractures in the subsurface due to the limited access. Hence, we propose a special optimization scheme to generate natural fracture geometry from the location of microseismic events. Accordingly, the criteria of evaluating the fitness of natural fracture realizations is defined as the total minimum distance squares of all microseismic events, which is the sum of minimum square distance for all microseismic events. Moreover, an additional constraint in this problem is that we need to set a minimum distance between fracture grids. Using generated natural fracture realizations, forward field-scale simulations are implemented using cohesive finite element analysis to find the best match with the recorded bottomhole pressure. To show the robustness of the proposed workflow for real field problem, we implemented this technique on available data from several well Chicontepec

  19. Modelling fracture in fibrous microstructures

    SciTech Connect

    Beyerlein, I.

    1998-04-01

    This work describes some complementary studies directed towards micromechanical modeling and simulation of the statistical fracture process in composites with fibrous microstructures. A few studies involve combining efficient computational stress analyses and piezospectroscopic measurement techniques to quantify interface deformation around a single break in model composites. It is shown how estimated interface parameters can be used to predict activity around more complex break arrangement in much larger composites. The final studies involve incorporating these experimentally refined stress analyses into large scale simulation for statistical predictions and subsequent analytical modeling of composite fracture.

  20. Slab melting and magma formation beneath the southern Cascade arc

    NASA Astrophysics Data System (ADS)

    Walowski, K. J.; Wallace, P. J.; Clynne, M. A.; Rasmussen, D. J.; Weis, D.

    2016-07-01

    The processes that drive magma formation beneath the Cascade arc and other warm-slab subduction zones have been debated because young oceanic crust is predicted to largely dehydrate beneath the forearc during subduction. In addition, geochemical variability along strike in the Cascades has led to contrasting interpretations about the role of volatiles in magma generation. Here, we focus on the Lassen segment of the Cascade arc, where previous work has demonstrated across-arc geochemical variations related to subduction enrichment, and H-isotope data suggest that H2O in basaltic magmas is derived from the final breakdown of chlorite in the mantle portion of the slab. We use naturally glassy, olivine-hosted melt inclusions (MI) from the tephra deposits of eight primitive (MgO > 7 wt%) basaltic cinder cones to quantify the pre-eruptive volatile contents of mantle-derived melts in this region. The melt inclusions have B concentrations and isotope ratios that are similar to mid-ocean ridge basalt (MORB), suggesting extensive dehydration of the downgoing plate prior to reaching sub-arc depths and little input of slab-derived B into the mantle wedge. However, correlations of volatile and trace element ratios (H2O/Ce, Cl/Nb, Sr/Nd) in the melt inclusions demonstrate that geochemical variability is the result of variable addition of a hydrous subduction component to the mantle wedge. Furthermore, correlations between subduction component tracers and radiogenic isotope ratios show that the subduction component has less radiogenic Sr and Pb than the Lassen sub-arc mantle, which can be explained by melting of subducted Gorda MORB beneath the arc. Agreement between pMELTS melting models and melt inclusion volatile, major, and trace element data suggests that hydrous slab melt addition to the mantle wedge can produce the range in primitive compositions erupted in the Lassen region. Our results provide further evidence that chlorite-derived fluids from the mantle portion of the

  1. Wave Propagation in Fractured Anisotropic Media

    NASA Astrophysics Data System (ADS)

    Shao, S.; Pyrak-Nolte, L. J.

    2012-12-01

    Discontinuities such as fractures, joints and faults occur in the Earth's crusts in a variety of rock types. While much theoretical, experimental and computational research have examined seismic wave propagation in fractured isotropic rock, few experimental studies have investigated seismic wave propagation in fractured anisotropic media. The co-existence of fractures and layers can complicate the interpretation of seismic properties because of the discrete guided modes that propagate along or are confined by the fractures. In this study, we use seismic arrays and acoustic wavefront imaging techniques to examine the competing sources of seismic anisotropy from fractures and from layers. Samples with textural anisotropy (100 mm x 100 mm x 100 mm) were fabricated from garolite, an epoxy - cloth laminate, with layer thickness 0f ~ 0.5 mm. Two sets of fractured samples were fabricated: (1) two single fractured samples with one fracture either parallel or (and) perpendicular to layers, and (2) four multi-fractured samples with 5 parallel fractures oriented either parallel, 30 degrees, 60 degrees or perpendicular to the layers. An intact sample containing no fractures was used as a standard orthorhombic medium for reference. Seismic arrays were used on the first set of samples to measure bulk waves and fracture interface waves as a function of stress. The seismic array contained two compressional and five shear-wave source-receiver pairs with a central frequency of 1 MHz. Shear wave transducers were polarized both perpendicular and parallel to the layering as well as to the fracture. Measurements were made for a range of stresses (0.4 - 4MPa). From these measurements it was observed that a fractured layered medium appears more isotropic or anisotropic than the orthorhombic background, depending on the orientation of the fracture relative to layers. The matrix anisotropy was recovered by increasing the normal stress on a fracture (i.e., by closing the fracture). For the

  2. Novel, near-infrared spectroscopic, label-free, techniques to assess bone abnormalities such as Paget's disease, osteoporosis and bone fractures

    NASA Astrophysics Data System (ADS)

    Sordillo, Diana C.; Sordillo, Laura A.; Shi, Lingyan; Budansky, Yury; Sordillo, Peter P.; Alfano, Robert R.

    2015-02-01

    Near- infrared (NIR) light with wavelengths from 650 nm to 950 nm (known as the first NIR window) has conventionally been used as a non-invasive technique that can reach deeper penetration depths through media than light at shorter wavelengths. Recently, several novel, NIR, label-free, techniques have been developed to assess Paget's disease of bone, osteoporosis and bone microfractures. We designed a Bone Optical Analyzer (BOA) which utilizes the first window to measure changes of Hb and HbO2. Paget's disease is marked by an increase in vascularization in bones, and this device can enable easy diagnosis and more frequent monitoring of the patient's condition, without exposing him to a high cumulative dose of radiation. We have also used inverse imaging algorithms to reconstruct 2D and 3D maps of the bone's structure. This device could be used to assess diseases such as osteoporosis. Using 800 nm femtosecond excitation with two-photon (2P) microscopy, we acquired 2PM images of the periosteum and spatial frequency spectra (based on emission of collagen) from the periosteal regions. This technique can provide information on the structure of the periosteum and can detect abnormalities which may be an indication of disease. Most recently, we showed that longer NIR wavelengths in the second and third NIR windows (1100 nm-1350 nm, 1600 nm-1870 nm), could be used to image bone microfractures. Use of NIR light could allow for repeated studies in patients with diseases such as Paget's and osteoporosis quickly and non-invasively, and could impact the current management for these diseases.

  3. New seismological evidence for fragmentation of the Tethys slab beneath Anatolia

    NASA Astrophysics Data System (ADS)

    Govers, R. M. A.; Fichtner, A.

    2015-12-01

    When oceanic basins close after a long period of convergence and subduction, continental collision and mountain building is a common consequence. The eastern Mediterranean basin is the last remainder of a once hemispherical neo-Tethys ocean that has nearly disappeared due to convergence of the India and Africa/Arabia plates with the Eurasia plate. New results from full waveform inversion for Anatolia give an unprecedented view on the crust and the upper mantle of the region. Based on highly accurate spectral-element simulations of seismic wave propagation in heterogeneous Earth models, full waveform inversion exploits complete seismograms - including body and surface waves - for the benefit of improved resolution. Furthermore, 3D structure in both crust and mantle is constrained jointly, thereby avoiding contamination from commonly applied crustal corrections. Second-order adjoint techniques provide quantitative estimates of direction- and position-dependent resolution length, which is essential for the interpretation of the model. The images connect major structures in the crust as documented in the geology, to features in the upper mantle that reflect the remnants of the convergence and collision. The results show a major discontinuity between western Anatolia lithosphere and the region to the east of it. It is the imprint of syn-collisional segmentation of the neo-Tethys slab, and separates the Aegean and west Anatolia regions from central and east Anatolia. While convergence between Africa and Europe continued, this initiated a period of lithospheric extension in the west and flat slab subduction in the east that set the stage for earthquake and volcanic activity in the region today. Slab segmentation is expected to have been relatively common just prior to closure of other oceans in the geological past, and may explain some of the complexity that geologists have documented in, for instance, the Tibetan plateau also.

  4. New seismological evidence for fragmentation of the Tethys slab beneath Anatolia

    NASA Astrophysics Data System (ADS)

    Govers, Rob; Fichtner, Andreas

    2015-04-01

    When oceanic basins close after a long period of convergence and subduction, continental collision and mountain building is a common consequence. The eastern Mediterranean basin is the last remainder of a once hemispherical neo-Tethys ocean that has nearly disappeared due to convergence of the India and Africa/Arabia plates with the Eurasia plate. New results from full waveform inversion for Anatolia give an unprecedented view on the crust and the upper mantle of the region. Based on highly accurate spectral-element simulations of seismic wave propagation in heterogeneous Earth models, full waveform inversion exploits complete seismograms - including body and surface waves - for the benefit of improved resolution. Furthermore, 3D structure in both crust and mantle is constrained jointly, thereby avoiding contamination from commonly applied crustal corrections. Second-order adjoint techniques provide quantitative estimates of direction- and position-dependent resolution length, which is essential for the interpretation of the model. The images connect major structures in the crust as documented in the geology, to features in the upper mantle that reflect the remnants of the convergence and collision. The results show a major discontinuity between western Anatolia lithosphere and the region to the east of it. It is the imprint of syn-collisional segmentation of the neo-Tethys slab, and separates the Aegean and west Anatolia regions from central and east Anatolia. While convergence between Africa and Europe continued, this initiated a period of lithospheric extension in the west and flat slab subduction in the east that set the stage for earthquake and volcanic activity in the region today. Slab segmentation is expected to have been relatively common just prior to closure of other oceans in the geological past, and may explain some of the complexity that geologists have documented in, for instance, the Tibetan plateau also.

  5. Equilibrium Slab Models of Lyman-Alpha Clouds

    NASA Technical Reports Server (NTRS)

    Charlton, Jane C.; Salpeter, Edwin E.; Hogan, Craig J.

    1993-01-01

    We model the L(sub y(alpha)) clouds as slabs of hydrogen with an ionizing extragalactic radiation field incident from both sides. In general, the equilibrium configuration of a slab at redshift z approx. less than 5 is determined by a balance of the gas pressure, gravity (including the effects of a dark matter halo), and the pressure exerted by the inter-galactic medium, P(sub ext). These models have been used to make predictions of the number of slabs as a function of the neutral hydrogen column density, N(sub H). A break in the curve is predicted at the transition between regimes where gravity and pressure are the dominant confining forces, with a less rapid decrease at larger N(sub H). The transition from optically thin to optically thick slabs leads to a gap in the distribution, whose location is governed largely by the spectrum of ionizing radiation. There are certain parallels between lines of sight through the outer HI disk of spiral galaxy with increasing radius, and the progression from damped, to Lyman limit, to forest clouds. We discuss briefly the possibility that at least some of the observed low z forest clouds may be a separate population, associated with galaxies, as suggested by the observations of Bahcall et al. This population could dominate the forest at present if the dark matter attached to galaxies should lead to gravity confinement for this disk population, while the isolated clouds remain pressure confined. The formalism developed in this paper will allow a more detailed study. We also discuss a more general parameter study of the equilibrium configuration of slabs, including mock gravity and L(sub y(alpha)) photon trapping.

  6. Assimilating lithosphere and slab history in 4-D Earth models

    NASA Astrophysics Data System (ADS)

    Bower, Dan J.; Gurnis, Michael; Flament, Nicolas

    2015-01-01

    We develop methods to incorporate paleogeographical constraints into numerical models of mantle convection. Through the solution of the convection equations, the models honor geophysical and geological data near the surface while predicting mantle flow and structure at depth and associated surface deformation. The methods consist of four constraints determined a priori from a plate history model: (1) plate velocities, (2) thermal structure of the lithosphere, (3) thermal structure of slabs in the upper mantle, and (4) velocity of slabs in the upper mantle. These constraints are implemented as temporally- and spatially-dependent conditions that are blended with the solution of the convection equations at each time step. We construct Earth-like regional models with oceanic and continental lithosphere, trench migration, oblique subduction, and asymmetric subduction to test the robustness of the methods by computing the temperature, velocity, and buoyancy flux of the lithosphere and slab. Full sphere convection models demonstrate how the methods can determine the flow associated with specific tectonic environments (e.g., back-arc basins, intraoceanic subduction zones) to address geological questions and compare with independent data, both at present-day and in the geological past (e.g., seismology, residual topography, stratigraphy). Using global models with paleogeographical constraints we demonstrate (1) subduction initiation at the Izu-Bonin-Mariana convergent margin and flat slab subduction beneath North America, (2) enhanced correlation of model slabs and fast anomalies in seismic tomography beneath North and South America, and (3) comparable amplitude of dynamic and residual topography in addition to improved spatial correlation of dynamic and residual topography lows.

  7. Slab melting and magma generation beneath the southern Cascade Arc

    NASA Astrophysics Data System (ADS)

    Walowski, K. J.; Wallace, P. J.; Clynne, M. A.

    2014-12-01

    Magma formation in subduction zones is interpreted to be caused by flux melting of the mantle wedge by fluids derived from dehydration of the downgoing oceanic lithosphere. In the Cascade Arc and other hot-slab subduction zones, however, most dehydration reactions occur beneath the forearc, necessitating a closer investigation of magma generation processes in this setting. Recent work combining 2-D steady state thermal models and the hydrogen isotope composition of olivine-hosted melt inclusions from the Lassen segment of the Cascades (Walowski et al., 2014; in review) has shown that partial melting of the subducted basaltic crust may be a key part of the subduction component in hot arcs. In this model, fluids from the slab interior (hydrated upper mantle) rise through the slab and cause flux-melting of the already dehydrated MORB volcanics in the upper oceanic crust. In the Shasta and Lassen segments of the southern Cascades, support for this interpretation comes from primitive magmas that have MORB-like Sr isotope compositions that correlate with subduction component tracers (H2O/Ce, Sr/P) (Grove et al. 2002, Borg et al. 2002). In addition, mass balance calculations of the composition of subduction components show ratios of trace elements to H2O that are at the high end of the global arc array (Ruscitto et al. 2012), consistent with the role of a slab-derived melt. Melting of the subducted basaltic crust should contribute a hydrous dacitic or rhyolitic melt (e.g. Jego and Dasgupta, 2013) to the mantle wedge rather than an H2O-rich aqueous fluid. We are using pHMELTS and pMELTS to model the reaction of hydrous slab melts with mantle peridotite as the melts rise through the inverted thermal gradient in the mantle wedge. The results of the modeling will be useful for understanding magma generation processes in arcs that are associated with subduction of relatively young oceanic lithosphere.

  8. Toughness-Dominated Regime of Hydraulic Fracturing in Cohesionless Materials

    NASA Astrophysics Data System (ADS)

    Germanovich, L. N.; Hurt, R. S.; Ayoub, J.; Norman, W. D.

    2011-12-01

    This work examines the mechanisms of hydraulic fracturing in cohesionless particulate materials with geotechnical, geological, and petroleum applications. For this purpose, experimental techniques have been developed, and used to quantify the initiation and propagation of hydraulic fractures in saturated particulate materials. The fracturing liquid is injected into particulate materials, which are practically cohesionless. The liquid flow is localized in thin self-propagating crack-like conduits. By analogy we call them 'cracks' or 'hydraulic fractures.' When a fracture propagates in a solid, new surfaces are created by breaking material bonds. Consequently, the material is in tension at the fracture tip. Because the particulate material is already 'fractured,' no new surface is created and no fracturing process per se is involved. Therefore, the conventional fracture mechanics principles cannot be directly applied. Based on the laboratory observations, performed on three particulate materials (Georgia Red Clay, silica flour, and fine sand, and their mixtures), this work offers physical concepts to explain the observed phenomena. The goal is to determine the controlling parameters of fracture behavior and to quantify their effects. An important conclusion of our work is that all parts of the cohesionless particulate material (including the tip zone of hydraulic fracture) are likely to be in compression. The compressive stress state is an important characteristic of hydraulic fracturing in particulate materials with low, or no, cohesion (such as were used in our experiments). At present, two kinematic mechanisms of fracture propagation, consistent with the compressive stress regime, can be offered. The first mechanism is based on shear bands propagating ahead of the tip of an open fracture. The second is based on the tensile strain ahead of the fracture tip and reduction of the effective stresses to zero within the leak-off zone. Scaling indicates that in our

  9. Numerical Investigation of Fracture Propagation in Geomaterials

    NASA Astrophysics Data System (ADS)

    Newell, P.; Borowski, E.; Major, J. R.; Eichhubl, P.

    2015-12-01

    Fracture in geomaterials is a critical behavior that affects the long-term structural response of geosystems. The processes involving fracture initiation and growth in rocks often span broad time scales and size scales, contributing to the complexity of these problems. To better understand fracture behavior, the authors propose an initial investigation comparing the fracture testing techniques of notched three-point bending (N3PB), short rod (SR), and double torsion (DT) on geomaterials using computational analysis. Linear softening cohesive fracture modeling (LCFM) was applied using ABAQUS to computationally simulate the three experimental set-ups. By applying material properties obtained experimentally, these simulations are intended to predict single-trace fracture growth. The advantages and limitations of the three testing techniques were considered for application to subcritical fracture propagation taking into account the accuracy of constraints, load applications, and modes of fracture. This work is supported as part of the Geomechanics of CO2 Reservoir Seals, a DOE-NETL funded under Award Number DE-FOA-0001037. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  10. Fracture mechanics of cellular glass

    NASA Technical Reports Server (NTRS)

    Zwissler, J. G.; Adams, M. A.

    1981-01-01

    The fracture mechanics of cellular glasses (for the structural substrate of mirrored glass for solr concentrator reflecting panels) are discussed. Commercial and developmental cellular glasses were tested and analyzed using standard testing techniques and models developed from linear fracture mechanics. Two models describing the fracture behavior of these materials were developed. Slow crack growth behavior in cellular glass was found to be more complex than that encountered in dense glasses or ceramics. The crack velocity was found to be strongly dependent upon water vapor transport to the tip of the moving crack. The existence of a static fatigue limit was not conclusively established, however, it is speculated that slow crack growth behavior in Region 1 may be slower, by orders of magnitude, than that found in dense glasses.

  11. Fractures of the forefoot.

    PubMed

    Mandracchia, Vincent J; Mandi, Denise M; Toney, Patris A; Halligan, Jennifer B; Nickles, W Ashton

    2006-04-01

    Fractures of the forefoot are common injuries of various causes. Although not crippling, forefoot fractures can be debilitating if they go undiagnosed or are mistreated. Whenever patients complain of foot pain with ambulation or difficulty ambulating, radiographs should be taken as part of a standard routine to assess for bony pathology. This article discusses the classification and treatment of metatarsal fractures, digital and sesamoid fractures, and open fractures about the forefoot.

  12. Multiple folded resonator for LD pulse end pumped Q-switched Yb:YAG slab laser.

    PubMed

    Jun, Liu; Jianguo, Xin; Ye, Lang; Jiabin, Chen

    2014-09-01

    In this paper, a multiple folded resonator is presented which consists of a multiple optical folding setup, a flat total reflector, a flat output coupler, a Q-switch crystal and a polarizer. By this technique, the output energy of 32.6mJ and pulse width of 13.4ns with a repetition rate of 5Hz was obtained, which is three times higher than that reported in the past publications by the use of the currently existing technique of the Q-switched slab gain lasers with the unstable resonator. The output beam with a quality of M² = 1.55 in the slow axis and M² = 1.40 in the fast axis was also obtained. PMID:25321590

  13. Frontal Sinus Fractures: Current Concepts

    PubMed Central

    Strong, E. Bradley

    2009-01-01

    Frontal sinus injuries may range from isolated anterior table fractures resulting in a simple aesthetic deformity to complex fractures involving the frontal recess, orbits, skull base, and intracranial contents. The risk of long-term morbidity can be significant. Optimal treatment strategies for the management of frontal sinus fractures remain controversial. However, it is critical to have a thorough understanding of frontal sinus anatomy as well as the current treatment strategies used to manage these injuries. A thorough physical exam and thin-cut, multiplanar (axial, coronal, and sagittal) computed tomography scan should be performed in all patients suspected of having a frontal sinus fracture. The most appropriate treatment strategy can be determined by assessing five anatomic parameters including the: frontal recess, anterior table integrity, posterior table integrity, dural integrity, and presence of a cerebrospinal fluid leak. A well thought out management strategy and meticulous surgical techniques are critical to success. The primary surgical goal is to provide a safe sinus while minimizing patient morbidity. This article offers an anatomically based treatment algorithm for the management of frontal sinus fractures and highlights the key steps to surgical repair. PMID:22110810

  14. Avalanche weak layer shear fracture parameters from the cohesive crack model

    NASA Astrophysics Data System (ADS)

    McClung, David

    2014-05-01

    Dry slab avalanches release by mode II shear fracture within thin weak layers under cohesive snow slabs. The important fracture parameters include: nominal shear strength, mode II fracture toughness and mode II fracture energy. Alpine snow is not an elastic material unless the rate of deformation is very high. For natural avalanche release, it would not be possible that the fracture parameters can be considered as from classical fracture mechanics from an elastic framework. The strong rate dependence of alpine snow implies that it is a quasi-brittle material (Bažant et al., 2003) with an important size effect on nominal shear strength. Further, the rate of deformation for release of an avalanche is unknown, so it is not possible to calculate the fracture parameters for avalanche release from any model which requires the effective elastic modulus. The cohesive crack model does not require the modulus to be known to estimate the fracture energy. In this paper, the cohesive crack model was used to calculate the mode II fracture energy as a function of a brittleness number and nominal shear strength values calculated from slab avalanche fracture line data (60 with natural triggers; 191 with a mix of triggers). The brittleness number models the ratio of the approximate peak value of shear strength to nominal shear strength. A high brittleness number (> 10) represents large size relative to fracture process zone (FPZ) size and the implications of LEFM (Linear Elastic Fracture Mechanics). A low brittleness number (e.g. 0.1) represents small sample size and primarily plastic response. An intermediate value (e.g. 5) implies non-linear fracture mechanics with intermediate relative size. The calculations also implied effective values for the modulus and the critical shear fracture toughness as functions of the brittleness number. The results showed that the effective mode II fracture energy may vary by two orders of magnitude for alpine snow with median values ranging from 0

  15. A Spatial Clustering Approach for Stochastic Fracture Network Modelling

    NASA Astrophysics Data System (ADS)

    Seifollahi, S.; Dowd, P. A.; Xu, C.; Fadakar, A. Y.

    2014-07-01

    Fracture network modelling plays an important role in many application areas in which the behaviour of a rock mass is of interest. These areas include mining, civil, petroleum, water and environmental engineering and geothermal systems modelling. The aim is to model the fractured rock to assess fluid flow or the stability of rock blocks. One important step in fracture network modelling is to estimate the number of fractures and the properties of individual fractures such as their size and orientation. Due to the lack of data and the complexity of the problem, there are significant uncertainties associated with fracture network modelling in practice. Our primary interest is the modelling of fracture networks in geothermal systems and, in this paper, we propose a general stochastic approach to fracture network modelling for this application. We focus on using the seismic point cloud detected during the fracture stimulation of a hot dry rock reservoir to create an enhanced geothermal system; these seismic points are the conditioning data in the modelling process. The seismic points can be used to estimate the geographical extent of the reservoir, the amount of fracturing and the detailed geometries of fractures within the reservoir. The objective is to determine a fracture model from the conditioning data by minimizing the sum of the distances of the points from the fitted fracture model. Fractures are represented as line segments connecting two points in two-dimensional applications or as ellipses in three-dimensional (3D) cases. The novelty of our model is twofold: (1) it comprises a comprehensive fracture modification scheme based on simulated annealing and (2) it introduces new spatial approaches, a goodness-of-fit measure for the fitted fracture model, a measure for fracture similarity and a clustering technique for proposing a locally optimal solution for fracture parameters. We use a simulated dataset to demonstrate the application of the proposed approach

  16. Fluid-Mobile Element Systematics in the Trans-Mexican Belt: Consequences of Slab Age or Evidence for Greater Geodynamic Complexity?

    NASA Astrophysics Data System (ADS)

    Grose, C. J.

    2008-05-01

    It is a generally accepted idea that the strong relationship between the age of oceanic lithosphere and its thermal structure will predictably manifest itself in the thermal state of associated subduction systems. Young-warm subducting slabs (eg. Cascadia) should correspond with warmer fore- and sub-arc temperatures and older- colder slabs (eg. Tonga) should feature colder temperatures. Strong support for the causal relationship has been derived from fluid-mobile elements (FME) in arc lavas. Old-cold subduction allows the slab to retain fluid-mobile species in hydrated mineral phases to greater depths resulting in a higher dehydration flux in the subarc. The greater heat contribution of young-warm slabs results in the premature release of bound water in the forearc and FME-depleted material is carried past the melt region. Recent efforts to characterize the along-arc systematics of FME's in the TMVB have shown moderate elevations of the FME B and B/Be in the Eastern Guerrero region, suggested to be a predictable consequence of the moderate increase in age of the downgoing slab (~12 Ma in the west to 16 Ma in the east). However, using thermal modelling techniques I show that low-angle subduction and the greater trench-to-subarc travel time for the Eastern slab results in unexpectedly warmer temperatures in the hydrated crust of the slab as it nears the subarc. Because the Eastern plate is initially colder, the FME data becomes difficult to explain since the old-cold and young-warm dichotomy in the context of subduction does not apply in this region. I suggest that the elevated FME signatures are instead a consequence of the mechanical entrainment of forearc material with the downgoing slab, increasing the inventory of hydrated FME-enriched material introduced into the mantle wedge. This may also suggest that low-angle and flat-slab geometries may help facilitate forearc erosion by increasing shear forces near the thrust interface. Furthermore, because 10B is

  17. A New Instrument for Magnetic Imaging of Rock Slabs at the Hand-Sample Scale

    NASA Astrophysics Data System (ADS)

    Brown, L. L.; Webber, J. R.; Williams, M. L.; Sweeney, J.

    2015-12-01

    Magnetic imaging techniques have provided a wealth of detailed information typically at two disparate spatial scales including the regional (e.g. satellite, airborne, and marine) and grain scales (e.g. Bitter colloid and magnetic force microscopy). However, there is a general lack of imaging techniques at the hand sample scale. We present a new instrument, procedure, and processing routine that automatically maps the magnetic flux density vector field above a slab of rock at a sub-millimeter resolution, which bridges the gap between the traditional magnetic mapping scales. This low-cost instrument consists of two linear axes that position and raster a stylus across the surface of a sample. Attached to the stylus is a MAG3110 triple axis magnetometer, which has an optimal spatial resolution of approximately 1 mm2. This technique has been particularly informative for metamorphic studies concerning the equilibria of ferrimagnetic minerals such as magnetite. For example, magnetic images have revealed complex anomalies within mafic granulites that indicate the heterogeneous production and removal of magnetite. Some mafic dikes display magnetic anomalies that are associated with partial retrograde metamorphism and hydration. Magnetic images of a sample of banded iron formation have documented sedimentary layering, as well as positive anomalies associated with the occurrence of leucosome. This association may provide key implications for anatectic redox reactions. Specimens extracted from various locations on slabs characterized by heterogeneous magnetic anomalies can be used to document disparate magnetic properties such as magnetic susceptibility, NRM, hysteresis, and coercivity distributions. As such, this technique may provide a context for targeted rock magnetic studies. The instrument provides a direct link for petrologic studies to magnetism that may be used as a small scale analog for regional and planetary magnetic anomalies.

  18. Enhanced output of soft X-ray lasers using double slab targets

    SciTech Connect

    Moreno, J.C.; Nilsen, J.; Chandler, E.

    1994-06-01

    Double slab neon-like niobium soft x-ray laser experiments have been performed using the Nova laser. The two slabs have their front surfaces facing in opposite directions with either a 300 {mu}m planar separation between them. Separate laser beams irradiate each slab with an intensity on target of 1.3 {times} 10{sup 14} W/cm{sup 2}. Best coupling was observed using a 300 {mu}m separation. The angular divergence of the laser is measured for single slab and double slab configurations. Comparisons to numerical models are discussed.

  19. Slab pull, mantle convection, and Pangaean assembly and dispersal

    NASA Astrophysics Data System (ADS)

    Collins, W. J.

    2003-01-01

    Two global-scale mantle convection cells presently exist on Earth, centred on upwelling zones in the South Pacific Ocean and northeast Africa: one cell (Panthalassan) contains only oceanic plates, the other (Pangaean) contains all the continental plates. They have remained fixed relative to one another for >400 Ma. A transverse (Rheic-Tethyian) subduction system splits the Pangaean cell. Poloidal plate motion in the oceanic cell reflects circumferential pull of Panthalassan slabs, but toroidal flow in the Pangaean cell, reflected by vortex-type motion of continents toward the Altaids of central-east Asia throughout the Phanerozoic, has resulted from the competing slab-pull forces of both cells. The combined slab-pull effects from both cells also controlled Pangaean assembly and dispersal. Assembly occurred during Palaeozoic clockwise toroidal motion in the Pangaean cell, when Gondwana was pulled into Pangaea by the NE-trending Rheic subduction zone, forming the Appalachian-Variscide-Altaid chain. Pangaean dispersal occurred when the Rheic trench re-aligned in the Jurassic to form the NW-trending Tethyside subduction system, which pulled east Gondwanan fragments in the opposite direction to form the Cimmerian-Himalayan-Alpine chain. This re-alignment also generated a new set of (Indian) mid-ocean ridge systems which dissected east Gondwana and facilitated breakup. 100-200-Myr-long Phanerozoic Wilson cycles reflect rifting and northerly migration of Gondwanan fragments across the Pangaean cell into the Rheic-Tethyian trench. Pangaean dispersal was amplified by retreat of the Panthalassan slab away from Europe and Africa, which generated mantle counterflow currents capable of pulling the Americas westward to create the Atlantic Ocean. Thermal blanketing beneath Pangaea and related hotspot activity were part of a complex feedback mechanism that established the breakup pattern, but slab retreat is considered to have been the main driving force. The size and longevity of

  20. Paratrooper's Ankle Fracture: Posterior Malleolar Fracture

    PubMed Central

    Young, Ki Won; Cho, Jae Ho; Kim, Hyung Seuk; Cho, Hun Ki; Lee, Kyung Tai

    2015-01-01

    Background We assessed the frequency and types of ankle fractures that frequently occur during parachute landings of special operation unit personnel and analyzed the causes. Methods Fifty-six members of the special force brigade of the military who had sustained ankle fractures during parachute landings between January 2005 and April 2010 were retrospectively analyzed. The injury sites and fracture sites were identified and the fracture types were categorized by the Lauge-Hansen and Weber classifications. Follow-up surveys were performed with respect to the American Orthopedic Foot and Ankle Society ankle-hindfoot score, patient satisfaction, and return to preinjury activity. Results The patients were all males with a mean age of 23.6 years. There were 28 right and 28 left ankle fractures. Twenty-two patients had simple fractures and 34 patients had comminuted fractures. The average number of injury and fractures sites per person was 2.07 (116 injuries including a syndesmosis injury and a deltoid injury) and 1.75 (98 fracture sites), respectively. Twenty-three cases (41.07%) were accompanied by posterior malleolar fractures. Fifty-five patients underwent surgery; of these, 30 had plate internal fixations. Weber type A, B, and C fractures were found in 4, 38, and 14 cases, respectively. Based on the Lauge-Hansen classification, supination-external rotation injuries were found in 20 cases, supination-adduction injuries in 22 cases, pronation-external rotation injuries in 11 cases, tibiofibular fractures in 2 cases, and simple medial malleolar fractures in 2 cases. The mean follow-up period was 23.8 months, and the average follow-up American Orthopedic Foot and Ankle Society ankle-hindfoot score was 85.42. Forty-five patients (80.36%) reported excellent or good satisfaction with the outcome. Conclusions Posterior malleolar fractures occurred in 41.07% of ankle fractures sustained in parachute landings. Because most of the ankle fractures in parachute injuries were