New concept for lifting in onshore oil wells

This paper presents the development of a prototype of a tubular linear induction motor applied to onshore oil exploitation, named MAT AE OS (which is the Portuguese acronym for Tubular Asynchronous Motor for Onshore Oil Exploitation). The function of this motor is to directly drive the sucker-rod pump installed in the down hole of the oil well. Considering the drawbacks and operational costs of the conventional oil extraction method, which is based on the walking beam and rod, string system, the developed prototype is intended to become a feasible alternative from both technical and economic points of view. At the present time, the MAT AE OS prototype is installed in a test bench at the Applied Electromagnetism Laboratory at the Escola Politecnica da Universidade de Sao Paulo. The complete testing system is controlled and supervised by special software, enabling good flexibility in operation, data acquisition, and performance analysis. The test results indicate that the motor develops a constant lift force along the pumping cycle, as shown by the measured dynamometric charts. Also, the evaluated electromechanical performance seems to be superior to that obtained by the traditional method. The system utilizing the MAT AE OS prototype allows the complete elimination of the rod string sets required by the conventional equipment, indicating that the new system may advantageously replace the surface mechanical components presently utilized.

Angioplasty and Stent Placement in Symptomatic Internal Carotid Occlusion

PURPOSE: To report a series of patients with symptomatic internal carotid artery (ICA) occlusion treated with angioplasty and stents. MATERIALS AND METHODS: From a consecutive series of 50 patients experiencing neurologic ischemic symptoms and shown by conventional ultrasonography (US) to have a total ICA occlusion, 16 patients (ages 45-79 years; mean, 63 y; 10 men) were selected between August 2006 to September 2008 to be treated with angioplasty based on discovery of an open ICA distal to the occlusion through contrast-enhanced echo Doppler imaging and/or multislice contrast computed tomography (CT). Angioplasty and stent placement were performed under cerebral protection. Follow-up duplex imaging was performed at 14 days and 3 months and every 6 months thereafter and CT follow-up was performed at 2-9 months; the mean follow-up period was 9.9 months. RESULTS: Lesion crossing and stent placement was successful in 13 of 16 patients. There were no deaths, conversions, cardiac complications, or major strokes. One patient had a transient mild hemiparesis in the upper limb, with total recovery in 3 months. At follow-up, all 13 patients with a good initial result remained with patent arterial lumens and resolution of neurologic ischemic symptoms. After 2-9 months, ICAs with a ""string sign"" had calibers close or equal to those of normal arteries. CONCLUSIONS: Angioplasty with stent placement is an effective treatment with a low morbidity rate for selected patients who continue to experience neurologic ischemic symptoms despite US findings of total occlusion of the ICA.

Transanal endorectal pull-through in children with Hirschsprung`s disease-technical refinements and comparison of results with the Duhamel procedure

Purpose: Transanal endorectal pull-through (TEPT) has drastically changed the treatment of Hirschsprung`s disease (HD). A short follow-up of children Submitted to TEPT reveals results that are similar to the classic transabdominal pull-through procedures. However, few reports compare the late results of TEPT with transabdominal pull-through procedures with respect to complication rates and the fecal continence. The aims of the present work are to describe some technical refinements that we introduced in the procedure and to compare the short and long-term outcome of TEPT with the outcomes of a group of patients with HD who previously underwent the Duhamel procedure. Methods: Thirty-five patients who underwent TEPT were prospectively studied and compared to a group of 29 patients who were treated with colostomy followed by a classical Duhamel pull-through. The main modifications introduced in the TEPT group were no preoperative colon preparation, operation conducted under general anesthesia in addition to regional sacral anesthesia, use of only one purse-string Suture in the rectal mucosa before transanal submucosal dissection, and no use of retractors and electrocautery during file submucosal dissection. Results: The most frequent early complications of TEPT group were perineal dermatitis (22.8%) and anastomotic strictures (8.6%). The comparison with patients who underwent Duhamel procedure revealed no difference in the incidence of preoperative enterocolitis, the patients of the TEPT group were younger at the time of diagnosis and of surgery, they had shorter operating times, and they began oral feeding more quickly after the operation. The incidence of wound infection was lower in the TEPT group. Moreover, the TEPT and Duhamel groups showed no difference in the incidences of mortality, postoperative partial continence, and total incontinence. Although the incidences of complete continence and postoperative enterocolitis were not different, a tendency to the increased incidence in the TEPT group was observed. Conclusions: This study further supports the technical advantages, the simplicity, and the decreased incidence of complications of a primary TEPT procedure when compared to a classical form of pull-through. Sonic technical refinements are described, and no preoperative colon preparation was necessary for the patients studied here. The results show that the long-term outcomes of the modified TEPT procedure are generally better than those obtained with classical approaches. Published by Elsevier Inc.

PHOTOELASTIC ANALISYS OF A HUMAN VERTEBRA MODEL WITH PEDICULAR SCREW

Introduction: The vertebrae fixation system using pedicular screws is one of the most efficient methods to treat vertebral spine pathologies. When the screw is submitted to pullout strength, it causes internal tension near the medullar canal and this situation can be analyzed by using the photoelasticity technique. Objective: Were analyzed those internal tensions near the medullar canal of photoelastic vertebra models using different sizes of screws of the vertebral fixation system submitted to pullout strength. Methods: A lumbar vertebral model made of photoelastic material with three different USS1-type pedicular screw sizes (5, 6, and 7 mm) was used. The internal tensions around the screw were tested in 12 predetermined points by a plain transmission polaroscope. Results: The areas of greater tension concentration were between the medullar canal and the curves of the transverse process. Comparing the maximum average pulling tension, statistical differences were observed between screws 5 and 7, and 6 and 7. On the other hand, for screws 5 and 6, there were no significant differences. Conclusion: The study evidenced that the internal tensions are greater in irregular areas, next to the medullar canal, showing that this is a critical region.

Al(2)O(3)/GdAlO(3)fiber for dental porcelain reinforcement

The aim of this study was to test the hypothesis that the addition of continuous or milled GdAlO(3)/Al(2)O(3) fibers to a dental porcelain increases its mechanical properties. Porcelain bars without reinforcement (control) were compared to those reinforced with long fibers (30 vol%). Also, disk specimens reinforced with milled fibers were produced by adding 0 (control), 5 or 10 vol% of particles. The reinforcement with continuous fibers resulted in significant increase in the uniaxial flexural strength from 91.5 to 217.4 MPa. The addition of varied amounts of milled fibers to the porcelain did not significantly affect its biaxial flexural strength compared to the control group. SEM analysis showed that the interface between the continuous fiber and the porcelain was free of defects. On the other hand, it was possible to note the presence of cracks surrounding the milled fiber/porcelain interface. In conclusion, the reinforcement of the porcelain with continuous fibers resulted in an efficient mechanism to increase its mechanical properties; however the addition of milled fibers had no significant effect on the material because the porcelain was not able to wet the ceramic particles during the firing cycle. (C) 2008 Elsevier Ltd. All rights reserved.

Testing the retention of attachments for implant overdentures - validation of an original force measurement system

P>The aim of this study was to validate an original portable device to measure attachment retention of implant overdentures both in the lab and in clinical settings. The device was built with a digital force measurement gauge (Imada) secured to a vertical wheel stand associated with a customized support to hold and position the denture in adjustable angulations. Sixteen matrix and patrix cylindrical stud attachments (Locator (R)) were randomly assigned as in vitro test specimens. Attachment abutments were secured in an implant analogue hung to the digital force gauge or to the load cell of a traction machine used as the gold standard (Instron Universal Testing Machine). Matrices were secured in a denture duplicate attached to the customized support, permitting reproducibility of their position on both pulling devices. Attachment retention in the axial direction was evaluated by measuring maximum dislodging force or peak load during five consecutive linear dislodgments of each attachment on both devices. After a wear simulation, retention was measured again at several time periods. The peak load measurements with the customized Imada device were similar to those obtained with the gold standard Instron machine. These findings suggest that the proposed portable device can provide accurate information on the retentive properties of attachment systems for removable dental prostheses.

Distinguishing links up to link-homotopy by algebraic methods

In this paper we provide a complete algebraic invariant of link-homotopy, that is, an algebraic invariant that distinguishes two links if and only if they are link-homotopic. The paper establishes a connection between the ""peripheral structures"" approach to link-homotopy taken by Milnor, Levine and others, and the string link action approach taken by Habegger and Lin. (C) 2009 Elsevier B.V. All rights reserved.

Liquid crystalline cellulosic elastomers: free standing anisotropic films under stretching

The structure and local ordering of 1,6-hexamethylenediisocyanate-(acetoxypropy1) cellulose (HDI-APC) liquid crystalline elastomer thin films are investigated by using X-ray diffraction and scattering techniques. Optical microscopy and mechanical essays are performed to complement the investigation. The study is performed in films subjected or not to an uniaxial stress. Our results indicate that the film is constituted by a bundle of helicoidal fiber-like structure, where the cellobiose block spins around the axis of the fiber, like a string-structure in a smectic-like packing, with the pitch defined by a smectic-like layer. The fibers are in average perpendicular to the smectic-like planes. Without the stretch, these bundles are warped, only with a residual orientation along the casting direction. The stretch orients the bundles along it, increasing the smectic-like and the nematic-like ordering of the fibers. Under stress, the network of molecules which connects the cellobiose blocs and forms the cellulosic matrix tends to organize their links in a hexagonal-like structure with lattice parameter commensurate to the smectic-like structure.

Pulsating strings in Lunin-Maldacena backgrounds

We consider pulsating strings in Lunin-Maldacena backgrounds, specifically in deformed Minkowski spacetime and deformed AdS(5) x S(5). We find the relation between the energy and the oscillation number of the pulsating string when the deformation is small. Since the oscillation number is an adiabatic invariant it can be used to explore the regime of highly excited string states. We then quantize the string and look for such a sector. For the deformed Minkowski background we find a precise match with the classical results if the oscillation number is quantized as an even number. For the deformed AdS(5) x S(5) we find a contribution which depends on the deformation parameter.

Notes on beta-deformations of the pure spinor superstring in AdS(5) x S(5)

We study the properties of the vertex operator for the beta-deformation of the superstring in AdS(5) x S(5) in the pure spinor formalism. We discuss the action of supersymmetry on the infinitesimal beta-deformation, the application of the homological perturbation theory, and the relation between the worldsheet description and the spacetime supergravity description. (C) 2011 Elsevier B.V. All rights reserved.

Quantum current algebra for the AdS(5) x S(5) superstring

The sigma model describing the dynamics of the superstring in the AdS(5) x S(5) background can be constructed using the coset PSU(2, 2 vertical bar 4)/SO(4, 1) x SO(5). A basic set of operators in this two dimensional conformal field theory is composed by the left invariant currents. Since these currents are not (anti) holomorphic, their OPE`s is not determined by symmetry principles and its computation should be performed perturbatively. Using the pure spinor sigma model for this background, we compute the one-loop correction to these OPE`s. We also compute the OPE`s of the left invariant currents with the energy momentum tensor at tree level and one loop.

Conservation laws and tachyon potentials in the sliver frame

Conservation laws have provided an elegant and efficient tool to evaluate the open string field theory interaction vertex, they have been originally implemented in the case where the string field is expanded in the Virasoro basis. In this work we derive conservation laws in the case where the string field is expanded in the so-called sliver L(0)-basis. As an application of this new set of conservation laws, we compute the open string field action relevant to the tachyon condensation and in order to present not only an illustration but also an additional information, we evaluate the action without imposing a gauge choice.

Effect of Eu(2)O(3) doping on Ta(2)O(5) crystal growth by the laser-heated pedestal technique

High energy band gap hosts doped with lanthanide ions are suitable for optical devices applications To study the potential of Ta(2)O(5) as a host compound pure and Eu(2)O(3)-doped Ta(2)O(5) crystal fibers were grown by the laser-heated pedestal growth technique in diameters ranging from 250 to 2600 pm and in lengths of up to 50 mm The axial temperature gradient at the solid/liquid interface of pure Ta(2)O(5) fibers revealed a critical diameter of 2200 gm above which the fiber cracks X-ray diffraction measurements of the pure Ta(2)O(5) single crystals showed a monoclinic symmetry and a growth direction of [1 (1) over bar 0] An analysis of the pulling rate as a function of the fiber diameter for Eu(2)O(3)-doped Ta(2)O(5) fibers indicated a well defined region in which constitutional supercooling is absent Photoluminescence measurements of pure Ta(2)O(5) crystals using excitation above the band gap (3 8 eV) were dominated by a broad unstructured green band that peaked at 500 nm Three Eu(3+)-related optical centers were identified in the doped samples with nominal concentrations exceeding 1 mol% Two of these centers were consistent with the ion in the monoclinic phase with different oxygen coordinations The third one was visible in the presence of the triclinic phase (C) 2010 Elsevier B V All rights reserved

On the generalized eigenvalue method for energies and matrix elements in lattice field theory

We discuss the generalized eigenvalue problem for computing energies and matrix elements in lattice gauge theory, including effective theories such as HQET. It is analyzed how the extracted effective energies and matrix elements converge when the time separations are made large. This suggests a particularly efficient application of the method for which we can prove that corrections vanish asymptotically as exp(-(E(N+1) - E(n))t). The gap E(N+1) - E(n) can be made large by increasing the number N of interpolating fields in the correlation matrix. We also show how excited state matrix elements can be extracted such that contaminations from all other states disappear exponentially in time. As a demonstration we present numerical results for the extraction of ground state and excited B-meson masses and decay constants in static approximation and to order 1/m(b) in HQET.

Only subtle protein conformational adaptations are required for ligand binding to thyroid hormone receptors: Simulations using a novel multipoint steered molecular dynamics approach

Thyroid hormone receptors (TR) are hormone-dependent transcription regulators that play a major role in human health, development, and metabolic functions. The thyroid hormone resistance syndrome, diabetes, obesity, and some types of cancer are just a few examples of important diseases that are related to TR malfunctioning, particularly impaired hormone binding. Ligand binding to and dissociation from the receptor ultimately control gene transcription and, thus, detailed knowledge of binding and release mechanisms are fundamental for the comprehension of the receptor`s biological function and development of pharmaceuticals. In this work, we present the first computational study of ligand entry into the ligand binding domain (LBD) of a nuclear receptor. We report molecular dynamics simulations of ligand binding to TRs using a generalization of the steered molecular dynamics technique designed to perform single-molecule pulling simulations along arbitrarily nonlinear driving pathways. We show that only gentle protein movements and conformational adaptations are required for ligand entry into the LBDs and that the magnitude of the forces applied to assist ligand binding are of the order of the forces involved in ligand dissociation. Our simulations suggest an alternative view for the mechanisms ligand binding and dissociation of ligands from nuclear receptors in which ligands can simply diffuse through the protein surface to reach proper positioning within the binding pocket. The proposed picture indicates that the large-amplitude protein motions suggested by the apo- and holo-RXR alpha crystallographic structures are not required, reconciling conformational changes of LBDs required for ligand entry with other nuclear receptors apo-structures that resemble the ligand-bound LBDs.