Technical Support of Performance Improvement for Resistance Welding Using Zr-4 Endcap and Endplate

Energy Technology Data Exchange (ETDEWEB)

Kim, Soo Sung

2008-10-15

The proper welding process for Zircaloy-4 endplate of PHWR and DUPIC fuel bundle assembly is considered important in respect to the soundness of weldment and the improvement of the performance of nuclear fuel bundle during the operation in reactor. The Zircaloy-4 endplate of PHWR and DUPIC fuel bundles are welded by the projection joint type, connecting the endcaps of fuel elements. Therefore, the purpose of this projection joint is to improve the welding quality of torque strength and welding deformation and to apply the commercial productions for the endplate welding of PHWR and DUPIC nuclear fuel bundle assembly.

Finite element analysis of an extended end-plate connection using the T-stub approach

Energy Technology Data Exchange (ETDEWEB)

Muresan, Ioana Cristina; Balc, Roxana [Technical University of Cluj-Napoca, Faculty of Civil Engineering. 15 C Daicoviciu Str., 400020, Cluj-Napoca (Romania)

2015-03-10

Beam-to-column end-plate bolted connections are usually used as moment-resistant connections in steel framed structures. For this joint type, the deformability is governed by the deformation capacity of the column flange and end-plate under tension and elongation of the bolts. All these elements around the beam tension flange form the tension region of the joint, which can be modeled by means of equivalent T-stubs. In this paper a beam-to-column end-plate bolted connection is substituted with a T-stub of appropriate effective length and it is analyzed using the commercially available finite element software ABAQUS. The performance of the model is validated by comparing the behavior of the T-stub from the numerical simulation with the behavior of the connection as a whole. The moment-rotation curve of the T-stub obtained from the numerical simulation is compared with the behavior of the whole extended end-plate connection, obtained by numerical simulation, experimental tests and analytical approach.

Influence of cortical endplates on ultrasonic properties of trabecular bone

International Nuclear Information System (INIS)

Kim, Yoon Mi; Lee, Kang Il

2015-01-01

The present study investigated the influence of thick cortical endplates on the ultrasonic properties of trabecular bone in a femur with a high fracture risk. Twelve trabecular bone samples were prepared from bovine femurs, and acrylic plates with thicknesses of 1.25, 1.80, and 2.75 mm were manufactured to simulate the cortical endplates using acrylic with a density and a sound speed similar to cortical bone. Although the thickness of the acrylic plates attached to the two sides of the trabecular bone increased, high correlations were observed between the speed of sound and the apparent bone density of the trabecular bone, with Pearson's correlation coefficients of 0.80-0.86. High correlations were also observed between the attenuation coefficient at 0.5 mm and the apparent bone density of the trabecular bone, with Pearson's correlation coefficients of 0.84-0.91. These results suggest that the speed of sound and attenuation coefficient at a specific frequency measured in a femur with relatively thick cortical endplates compared to the calcaneus could be used as indices for predicting the bone mineral density of the femur.

The change and differential findings of lumbar vertebral endplate on MRI

International Nuclear Information System (INIS)

Kanamori, Masahiko; Nobukiyo, Masanori; Shigeta, Tetsuya; Ishihara, Hirokazu; Kawaguchi, Yoshiharu; Yoshino, Osamu

2004-01-01

The purpose of this study is to evaluate the differential findings of vertebral endplate of lumbar spine on MRI. Infected disc showed the T1 low/T2 high (Modic type I) to T2 iso-signal intensity on MRI. Post-operated disc showed the Modic type I findings, although the degenerative disc showed the various kinds of types according to the Modic's classification (type I to III). The characteristics findings of the infected disc were T2-high signal intensity of nucleus purposes and the wide affected area of vertebra including endplate on T1 image compared with T2 image. (author)

Torque Measurement of Welding of Endplug-Endplate using Multi-pin Remote Welding System

Energy Technology Data Exchange (ETDEWEB)

Koo, Dae-Seo; Kim, Soo-Sung; Park, Geun-Il; Lee, Jung-Won; Song, Kee-Chan [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2006-07-01

As fuel bundles in PHWR irradiates, inner pressure in claddings of fuel rods increases owing to outer pressure and fission products of nuclear fissions. Because of leak possibility of welding between cladding and end plug, this welding part connects with safety of nuclear fuel rods. Because of importance of this welding part, weldability of end plug-cladding of nuclear fuel rods is continually researched. Welding method for research and commercialization is classified as melting, solid type welding or resistance welding. End plug cladding welding of nuclear fuel rods in PHWR takes advantage of resistance upset butt welding using multicycle mode. This method makes weld flash and shapes re-entrant corner owing to welding heat due to resistivity, contact resistance of cladding-end plug, and inelasticity deformation due to pressure. Welding part between cladding and end plug receives stresses and makes small cracks. In this study, remote welding system for multi-pin assembly was designed, fabricated and welding specimens of end plug-endplate were made using electrical resistance method. The torques of welding between end plug and endplate were measured. These results on welding current, pressure of main electrode and pressure of branch electrode were analyzed. Weldability between end plug and endplate was confirmed through metallographic examinations. In the future, optimal welding examinations due to welding current, welding pressure and welding time will be performed to improve weldability of end plug-endplate.

Evaluation on vertebral endplate injury and adjacent intervertebral disk injury of patients with osteoporotic vertebral compression fractures by MRI and its clinical significance

International Nuclear Information System (INIS)

Shen Yu; Shen Huiliang; Fang Xiutong; Zhang Wenbo

2012-01-01

Objective: To investigate the relationship between vertebral endplate injury and adjacent intervertebral disk injury of patients with acute or sub-acute osteoporotic vertebral compression fractures (OVC-F) by MRI, and to provide basis for diagnosis of OVCF. Methods: The clinical data of a total of 66 patients with OVCF underwent vertebroplasty (76 fracture of vertebral bodies) were selected. The vertebral endplate injury and adjacent intervertebral disk injury of OVCF patients were detected by MRI. Results: There were 57 vertebral endplate injury in 76 fracture vertebral bodies (75% ). There were only 27 vertebral bodies with vertebral endplate injury in 57 fracture vertebral bodies with endplate injury (47% ), and 22 vertebral with superior and inferior vertebral endplate injury (39% ), and 8 vertebral bodies with inferior vertebral endplate injury (14% ). There were 48 vertebral bodies with intervertebral disc injury in 76 fracture vertebral bodies (63% ). There were 22 intervertebral disc injury located above the fracture of the lumbar spine in 48 vertebral bodies with intervertebral disc injury (45% ), and 19 fracture vertebral bodies with upper and lower intervertebral disc injury (40% ), and 7 intervertebral injuries located below the fracture of the lumbar spine (15% ). Conclusion: Vertebral endplate injury is frequently associated with the adjacent intervertebral disk injury. The clinical diagnosis and treatment should be emphasized in the fracture vertebral endplate damage and adjacent intervertebral disc injury. (authors)

Neuromuscular activity of Bothrops fonsecai snake venom in vertebrate preparations

Science.gov (United States)

Fernandes, Carla T; Giaretta, Vânia MA; Prudêncio, Luiz S; Toledo, Edvana O; da Silva, Igor RF; Collaço, Rita CO; Barbosa, Ana M; Hyslop, Stephen; Rodrigues-Simioni, Léa; Cogo, José C

2014-01-01

The neuromuscular activity of venom from Bothrops fonsecai, a lancehead endemic to southeastern Brazil, was investigated. Chick biventer cervicis (CBC) and mouse phrenic nerve-diaphragm (PND) preparations were used for myographic recordings and mouse diaphragm muscle was used for membrane resting potential (RP) and miniature end-plate potential (MEPP) recordings. Creatine kinase release and muscle damage were also assessed. In CBC, venom (40, 80 and 160μg/ml) produced concentration- and time-dependent neuromuscular blockade (50% blockade in 85±9 min and 73±8 min with 80 and 160μg/ml, respectively) and attenuated the contractures to 110μM ACh (78–100% inhibition) and 40mM KCl (45–90% inhibition). The venom-induced decrease in twitch-tension in curarized, directly-stimulated preparations was similar to that in indirectly stimulated preparations. Venom (100 and 200μg/ml) also caused blockade in PND preparations (50% blockade in 94±13 min and 49±8 min with 100 and 200μg/ml, respectively) but did not alter the RP or MEPP amplitude. In CBC, venom caused creatine kinase release and myonecrosis. The venom-induced decrease in twitch-tension and in the contractures to ACh and K+ were abolished by preincubating venom with commercial antivenom. These findings indicate that Bothrops fonsecai venom interferes with neuromuscular transmission essentially through postsynaptic muscle damage that affects responses to ACh and KCl. These actions are effectively prevented by commercial antivenom. PMID:25028603

Autophagy Is a Protective Response to the Oxidative Damage to Endplate Chondrocytes in Intervertebral Disc: Implications for the Treatment of Degenerative Lumbar Disc

Directory of Open Access Journals (Sweden)

Ke Chen

2017-01-01

Full Text Available Low back pain (LBP is the leading cause of disability in the elderly. Intervertebral disc degeneration (IDD was considered as the main cause for LBP. Degeneration of cartilaginous endplate was a crucial harmful factor during the initiation and development of IDD. Oxidative stress was implicated in IDD. However, the underlying molecular mechanism for the degeneration of cartilaginous endplate remains elusive. Herein, we found that oxidative stress could induce apoptosis and autophagy in endplate chondrocytes evidenced by western blot analysis, flow cytometry, immunofluorescence staining, GFP-LC3B transfection, and MDC staining. In addition, we also found that the apoptosis of endplate chondrocytes was significantly increased after the inhibition of autophagy by bafilomycin A1 shown by flow cytometry. Furthermore, mTOR pathway upstream autophagy was greatly suppressed suggested by western blot assay. In conclusion, our study strongly revealed that oxidative stress could increase autophagy and apoptosis of endplate chondrocytes in intervertebral disc. The increase of autophagy activity could prevent endplate chondrocytes from apoptosis. The autophagy in endplate chondrocytes induced by oxidative stress was mTOR dependent. These findings might shed some new lights on the mechanism for IDD and provide new strategies for the treatments of IDD.

Behavior of four-bolt extended end-plate connection subjected to lateral loading

Directory of Open Access Journals (Sweden)

Elsayed Mashaly

2011-03-01

Full Text Available A considerable number of literatures have been published on the behavior of end-plate connections in ordinary moment-resisting frames. It was found, experimentally, that this type of connection might act as either a fully-rigid or a semi-rigid connection depending mainly on the thickness of the end plate and the diameter of bolts. In recent years, due to their good ductility and their good ability of energy dissipation, extended end-plate connections are recommended to be widely used in special moment-resisting frames subjected to lateral loads. The purpose of this study is to investigate the effect of both the material and geometric properties of four-bolt extended end-plate connections upon their behavior when subjected to lateral loading. This is done through a parametric study upon a finite element model using the multi-purpose software package ANSYS. The parametric study takes into account 12 parameters which are expected to be effective on the behavior of the studied connection. The results are presented by the relation between the storey drift, which represents the rotation of the connection and the applied lateral load, which simulates the moment on the connection. The results verify that the chosen parameters are considered effective depending on the energy dissipation of the connection.

Effect of prosthesis endplate lordosis angles on L5-S1 kinematics after disc arthroplasty.

Science.gov (United States)

Tsitsopoulos, Parmenion P; Wojewnik, Bartosz; Voronov, Leonard I; Havey, Robert M; Renner, Susan M; Zelenakova, Julia; McIntosh, Braden; Carandang, Gerard; Abjornson, Celeste; Patwardhan, Avinash G

2012-06-01

We hypothesized that L5-S1 kinematics will not be affected by the lordosis distribution between the prosthesis endplates. Twelve cadaveric lumbosacral spines (51.3 ± 9.8 years) were implanted with 6° or 11° prostheses (ProDisc-L) with four combinations of superior/inferior lordosis (6°/0°, 3°/3°, 11°/0°, 3°/8°). Specimens were tested intact and after prostheses implantation with different lordosis distributions. Center of rotation (COR) and range of motion (ROM) were quantified. Six-degree lordosis prostheses (n = 7) showed no difference in flexion-extension ROM, regardless of design (6°/0° or 3°/3°) (p > 0.05). In lateral bending (LB), both designs reduced ROM (p lordosis prostheses (n = 5) showed no difference in flexion-extension ROM for either design (p > 0.05). LB ROM decreased with distributed lordosis prostheses (3°/8°) (p lordosis distribution among the two prosthesis endplates. The ProDisc-L prosthesis design where all lordosis is concentrated in the superior endplate yielded COR locations that were anterior and caudal to intact controls. The prosthesis with lordosis distributed between the two endplates yielded a COR that tended to be closer to intact. Further clinical and biomechanical studies are needed to assess the long-term impact of lordosis angle distribution on the fate of the facet joints.

Indian hedgehog contributes to human cartilage endplate degeneration.

Science.gov (United States)

Wang, Shaowei; Yang, Kun; Chen, Shuai; Wang, Jiying; Du, Guoqing; Fan, Shunwu; Wei, Lei

2015-08-01

To determine the role of Indian hedgehog (Ihh) signaling in human cartilage endplate (CEP) degeneration. CEP-degenerated tissues from patients with Modic I or II changes (n = 9 and 45, respectively) and normal tissues from vertebral burst fracture patients (n = 17) were collected. Specimens were either cut into slices for organ culture ex vivo or digested to isolate chondrocytes for cell culture in vitro. Ihh expression and the effect of Ihh on cartilage degeneration were determined by investigating degeneration markers in this study. Ihh expression and cartilage degeneration markers significantly increased in the Modic I and II groups. The expression of cartilage degeneration markers was positively correlated with degeneration severity. Gain-of-function for Ihh promoted expression of cartilage degeneration markers in vitro, while loss-of-function for Ihh inhibited their expression both in vitro and ex vivo. These findings demonstrated that Ihh promotes CEP degeneration. Blocking Ihh pathway has potential clinical usage for attenuating CEP degeneration.

Longitudinal study of vertebral type-1 end-plate changes on MR of the lumbar spine

Energy Technology Data Exchange (ETDEWEB)

Mitra, D. [Department of Neuroradiology, Newcastle General Hospital, Westgate Road, NE4 6BE, Newcastle upon Tyne (United Kingdom); Cassar-Pullicino, V.N.; Mccall, I.W. [Department of Radiology, Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry (United Kingdom)

2004-09-01

The purpose of this study was to investigate the temporal evolution of type-1 end-plate changes on MRI in patients with degenerative disease of the lumbar spine and to evaluate whether any correlation exists between such evolution and the change in patients' symptoms. Forty-four patients with 48 Modic type-1 end-plate changes (low TI signal and high T2 signal) were studied. All patients had an initial and a follow-up non-contrast lumbar MRI with variable intervals between the studies (12-72 months). Severity of the end-plate changes was assessed by eyeball estimation. Correlation with patients' symptoms was studied with the help of the Visual Analogue Score (VAS), Oswestry Questionnaire Score (OQS) and patients' subjective assessment. Of the 48 disc levels with type-1 changes, 18 (37.5%) converted fully to type 2 (high T1 signal and intermediate to high T2 signal), 7 (14.6%) partially converted to type 2, 19 (39.6%) became worse (i.e. type 1 changes became more extensive) and 4 (8.3%) showed no change. Higher average VAS (5.7) and OQS (42.3) scores were noted in patients where there was worsening type-1 change and lower scores (3.8 and 27, respectively) were seen in those where there was conversion to type-2 change. These trends, however, did not reach statistical significance (P values 0.16 and 0.09 for VAS and OQS, respectively). The statistical relationship was stronger after exclusion of patients with confounding factors (i.e. changes in lumbar MRI other than end-plate changes that could independently explain the evolution of patients' symptoms) with P-values of 0.08 and 0.07 for VAS and OQS, respectively. Type-1 end-plate change represents a dynamic process and in a large majority of cases either converts to type-2 change or becomes more extensive. The evolution of type-1 change relates to change in patient's symptoms, but not to a statistically significant level. (orig.)

Longitudinal study of vertebral type-1 end-plate changes on MR of the lumbar spine

International Nuclear Information System (INIS)

Mitra, D.; Cassar-Pullicino, V.N.; Mccall, I.W.

2004-01-01

The purpose of this study was to investigate the temporal evolution of type-1 end-plate changes on MRI in patients with degenerative disease of the lumbar spine and to evaluate whether any correlation exists between such evolution and the change in patients' symptoms. Forty-four patients with 48 Modic type-1 end-plate changes (low TI signal and high T2 signal) were studied. All patients had an initial and a follow-up non-contrast lumbar MRI with variable intervals between the studies (12-72 months). Severity of the end-plate changes was assessed by eyeball estimation. Correlation with patients' symptoms was studied with the help of the Visual Analogue Score (VAS), Oswestry Questionnaire Score (OQS) and patients' subjective assessment. Of the 48 disc levels with type-1 changes, 18 (37.5%) converted fully to type 2 (high T1 signal and intermediate to high T2 signal), 7 (14.6%) partially converted to type 2, 19 (39.6%) became worse (i.e. type 1 changes became more extensive) and 4 (8.3%) showed no change. Higher average VAS (5.7) and OQS (42.3) scores were noted in patients where there was worsening type-1 change and lower scores (3.8 and 27, respectively) were seen in those where there was conversion to type-2 change. These trends, however, did not reach statistical significance (P values 0.16 and 0.09 for VAS and OQS, respectively). The statistical relationship was stronger after exclusion of patients with confounding factors (i.e. changes in lumbar MRI other than end-plate changes that could independently explain the evolution of patients' symptoms) with P-values of 0.08 and 0.07 for VAS and OQS, respectively. Type-1 end-plate change represents a dynamic process and in a large majority of cases either converts to type-2 change or becomes more extensive. The evolution of type-1 change relates to change in patient's symptoms, but not to a statistically significant level. (orig.)

The role of desensititation in decay time of miniature endplate currents in frogs Rana ridibunda and Rana temporaria

Czech Academy of Sciences Publication Activity Database

Giniatullin, R. A.; Talantova, M. V.; Vyskočil, František

2001-01-01

Roč. 39, č. 3 (2001), s. 287-292 ISSN 0168-0102 R&D Projects: GA AV ČR IAA7011902; GA MŠk VS97099; GA MŠk OK 267 Grant - others:RFBR(RU) 98-04-48044; INTAS(BE) 2000-1147 Institutional research plan: CEZ:AV0Z5011922 Keywords : frog * desensitisation * miniature endplate potential Subject RIV: ED - Physiology Impact factor: 1.770, year: 2001

Efficient multipartite entanglement purification with the entanglement link from a subspace

Energy Technology Data Exchange (ETDEWEB)

Deng Fuguo [Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Conventional University, Beijing 100875 (China)

2011-11-15

We present an efficient multipartite entanglement purification protocol (MEPP) for N-photon systems in a Greenberger-Horne-Zeilinger state with parity-check detectors. It contains two parts. One is the conventional MEPP with which the parties can obtain a high-fidelity N-photon ensemble directly, similar to the MEPP with controlled-not gates. The other is our recycling MEPP in which the entanglement link is used to produce some N-photon entangled systems from entangled N{sup '}-photon subsystems (2{<=}N{sup '}MEPPs. The entangled N{sup '}-photon subsystems are obtained efficiently by measuring the photons with potential bit-flip errors. With these two parts, the present MEPP has a higher efficiency than all other conventional MEPPs.

Relationship between screw sagittal angle and stress on endplate of adjacent segments after anterior cervical corpectomy and fusion with internal fixation: a Chinese finite element study.

Science.gov (United States)

Zhang, Yu; Tang, Yibo; Shen, Hongxing

2017-12-01

In order to reduce the incidence of adjacent segment disease (ASD), the current study was designed to establish Chinese finite element models of normal 3rd~7th cervical vertebrae (C3-C7) and anterior cervical corpectomy and fusion (ACCF) with internal fixation , and analyze the influence of screw sagittal angle (SSA) on stress on endplate of adjacent cervical segments. Mimics 8.1 and Abaqus/CAE 6.10 softwares were adopted to establish finite element models. For C4 superior endplate and C6 inferior endplate, their anterior areas had the maximum stress in anteflexion position, and their posterior areas had the maximum stress in posterior extension position. As SSA increased, the stress reduced. With an increase of 10° in SSA, the stress on anterior areas of C4 superior endplate and C6 inferior endplate reduced by 12.67% and 7.99% in anteflexion position, respectively. With an increase of 10° in SSA, the stress on posterior areas of C4 superior endplate and C6 inferior endplate reduced by 9.68% and 10.22% in posterior extension position, respectively. The current study established Chinese finite element models of normal C3-C7 and ACCF with internal fixation , and demonstrated that as SSA increased, the stress on endplate of adjacent cervical segments decreased. In clinical surgery, increased SSA is able to play important role in protecting the adjacent cervical segments and reducing the incidence of ASD.

The mechanisms of inhibition of frog endplate currents with homologous derivatives of the 1,1-dimethyl-3-oxybutyl phosphonic acid

Czech Academy of Sciences Publication Activity Database

Pryazhnikov, E.; Ostroumov, A.; Druginina, O.; Vyskočil, František; Skorinkin, A.

2012-01-01

Roč. 61, č. 4 (2012), s. 395-404 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA202/09/0806; GA AV ČR(CZ) IAA500110905 Institutional research plan: CEZ:AV0Z50110509 Keywords : endplate potential * nicotinic cholinoreceptor * allosteric modulation * open channel block * lipophilicity and cholinergic effect Subject RIV: ED - Physiology Impact factor: 1.531, year: 2012

A Relationship of the Torque Strength between Endplates and Endcaps due to the Welding Parameters

Energy Technology Data Exchange (ETDEWEB)

Koo, Dae Seo; Kim, Soo Sung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2008-10-15

As fuel bundles in a PHWR core irradiated, inner pressure in the claddings of the fuel rods increases owing to the outer pressure and fission products of the nuclear fissions. Because of a leak possibility from a welding between a cladding and an endcap, this welding part is connected with the safety of nuclear fuel rods. Endcap-cladding welding of nuclear fuel rods in a PHWR takes advantage of a resistance upset butt welding. The weldment between a cladding and an endcap is to be sound to prevent a leakage of fission products from a cladding as a UO{sub 2} pellet is irradiated. Weld flash was made from a deformation due to a welding heat and increasing the pressure of the resistivity and resistance from a cladding and an endcap. Weld line of a welding interface, microstructure of a weldment and a crystallographic structure change were sources of an iodine induced SCC in a reactor. The soundness of a weldment is important because a weld line connects the leakage of fission products from an operational reactor. In this study, welding specimens were fabricated by a resistance welding method using a fuel bundle welder to measure and analyze the torque strength of an endplate-endcap welding. The torque strength between endplates and endcaps was measured and analyzed with the welding current and the welding time. The torque strength between endplates and endcaps was, on the whole, within 6.9-12.7 N{center_dot}m in the range of fabrication specification of the fuel bundles. The weldability of between an endplate and an endcap was investigated by a metallographic examination.

The significance of calcified fibrocartilage on the cortical endplate of the translational sheep spine model.

Science.gov (United States)

Sinclair, Sarina K; Bell, Spencer; Epperson, Richard Tyler; Bloebaum, Roy D

2013-05-01

To gain an understanding of the vertebral cortical endplate and factors that may affect the ability to achieve skeletal attachment to intervertebral implants and fusion, this study aimed to characterize the hypermineralized tissue on the cortical endplate of the vertebral body on a commonly used animal model. Skeletally mature sheep were injected with tetracycline prior to euthanasia and the C2-C3, T5-T6, and L2-L3 spinal motion segments were excised and prepared. Vertebral tissues were imaged using backscatter electron (BSE) imaging, histology, and tetracycline labeling was used to assess bone remodeling within different tissue layers. It was determined that the hypermineralized tissue layer was calcified fibrocartilage (CFC). No tetracycline labels were identified in the CFC layer, in contrast to single and double labels that were present in the underlying bone, indicating the CFC present on the cortical endplate was not being actively remodeled. The average thickness of the CFC layer was 146.3 ± 70.53 µm in the cervical region, 98.2 ± 40.29 µm in the thoracic region, and 150.89 ± 69.25 µm in the lumbar region. This difference in thickness may be attributed to the regional biomechanical properties of the spine. Results from this investigation indicate the presence of a nonremodeling tissue on the cortical endplate of the vertebral body in sheep spines, which attaches the intervertebral disc to the vertebrae. This tissue, if not removed, would likely prevent successful bony attachment to an intervertebral device in spinal fusion studies and total disc replacement surgeries. Copyright © 2013 Wiley Periodicals, Inc.

Intra- and interobserver reproducibility of vertebral endplate signal (modic) changes in the lumbar spine

DEFF Research Database (Denmark)

Jensen, Tue Secher; Sorensen, Joan Solgaard; Kjær, Per

2007-01-01

. PURPOSE: To assess the intra- and interobserver reliability of the "Nordic Modic classification" protocol. MATERIAL AND METHODS: MRI scans of 50 individuals representative of the general Danish population aged 40 were evaluated by two observers. Criteria for grading the changes were developed...... by the Nordic Modic Consensus Group. After consensus was established, all 50 MRI examinations were evaluated independently by each observer. Intraobserver reliability was assessed by re-evaluation of the 50 examinations by one of the observers. Kappa statistics were used to calculate agreement. RESULTS: Intra....... CONCLUSION: In this study, we found convincing reproducibility of a detailed evaluation protocol of vertebral endplate signal changes, the "Nordic Modic Classification." The authors recommend that the evaluation protocol should be used in future studies investigating vertebral endplate signal changes....

Association of endothelin-1 expression and cartilaginous endplate degeneration in humans.

Directory of Open Access Journals (Sweden)

Wei Yuan

Full Text Available BACKGROUND: Inflammatory cytokines are involved in intervertebral disc (IVD degeneration. Endothelin-1 (ET-1, a 21-amino-acid cytokine implicated with cartilage degradation, is secreted by vascular endothelial cells and also by many other cell types. The expression of ET-1 in human IVD cartilage endplate (CEP and its role in disc degeneration have not been explored. METHODS AND FINDINGS: The expression of ET-1 in degenerated CEP was analyzed by immunohistochemical staining and Western blotting; ET-1 was demonstrated in cartilaginous endplate cells (CECs by immunofluorescent staining. The ET-1 mRNA expression and protein production by CECs stimulated by tumor necrosis factor alpha (TNF-α, a pro-inflammatory cytokine, were determined by real-time PCR analysis and Western blotting, respectively. The matrix metalloprotease-1 (MMP-1, MMP-13 and tissue inhibitor of metalloproteases-1 (TIMP-1 levels in the supernatant of cultured CECs treated with ET-1 were determined using enzyme-linked immunosorbent assays. Nitric oxide (NO release and nitric oxide synthase (NOS activity were measured using a spectrophotometric assay. The apoptosis of CECs by ET-1 was measured by an Annexin V-FITC detection assay. The production of ET-1 in degenerated cartilage endplate was significantly higher than normal CEP. The results showed that ET-1 was expressed by CECs and modulated by TNF-α in a dose-dependent manner. ET-1 increased production of MMP-1 and MMP-13, decreased TIMP-1 production, and induced NO and NOS release by cultured CECs. The direct stimulation of CECs by ET-1 did not promote cell apoptosis. CONCLUSION: The study results suggest that ET-1 played a pivotal role in human CEP degeneration, and may be a new target for development of therapies for this condition.

Predictors of new vertebral endplate signal (Modic) changes in the general population

DEFF Research Database (Denmark)

Jensen, Tue Secher; Kjaer, Per; Korsholm, Lars

2010-01-01

predictors of new VESC were female gender, disc-related MRI findings (disc degeneration, disc bulges, disc herniation, and other endplate changes) and lifestyle factors [high physical work or leisure activity, high body mass index (BMI), and heavy smoking]. Bivariate and multivariate logistic regressions...... with disc degeneration, bulges or herniations at 40 were the only predictors of new VESC at age 44. Therefore, the development of new VESC at the age of 44 appears to be based on the status and dynamics of the disc, rather than being the result of gender or lifestyle factors such as smoking and physical...... were used to identify predictors of new VESC. New VESC at the age of 44 appeared in 67 of the 344. The majority (84%) of these new signal changes were type 1 VESC and almost half (45%) were only in the endplate and did not extend into the vertebral body. In the multivariate analysis, lumbar disc levels...

Morphologic and radiologic data of isolated vertebral end-plates under particular consideration of radiodensitometry

International Nuclear Information System (INIS)

Unflath, U.

1979-01-01

The intention was to find examination techniques for macroscopico-morphological diagnosis, for quantification of the concavity and methods for roentgenologico-densitometric analysis of vertebral end-plates. The following factors were used for macromorphologic diagnosis: osteophytes, ridge constitution, ridge transition, cribriform plate and concavity. The radiodensitometric analysis comprised investigation of bone density, anisotropy and ridge mineralisation. The specimen were radiographed on a mammograph together with calcium chloride solutions of increasing concentration. Statistically significant differences in the behaviour of basal and upper plates were not observed. With reference to the factors osteophytes and ridge constitution the basal plates seem to be morphologically more variable than the upper plates. It resulted that the features absolute concavity and concavity quotient are highly appropriate factors to document the constitution of the isolated vertebral end-plates. Also the features density, anisotropy and ridge mineralisation were found to be useful for documentation. The result of data correlation was that high concavity quotients are accompanied by macroscopically medium- to small-sized pores. Density and anisotropy of the overall profiles do not show correlation, but voluminous cribriform laminae tend to develop more inhomogenic structures. As to be expected, bone density increases with macroscopic fine porosity. The higher the concavity quotient is, the smaller are the values for density, ridge mineralisation and anisotropy. Thus a high degree of vertebral end-plate concavity indicates reduced bone density and lower mineral content. (orig./MG) [de

Mechanisms of the inhibition of endplate acetylcholine receptors by antiseptic chlorhexidine (experiments and models)

Czech Academy of Sciences Publication Activity Database

Shaihutdinova, A.R.; Nikolsky, E. E.; Vyskočil, František; Skorinkin, A.I.

2009-01-01

Roč. 380, č. 6 (2009), s. 551-560 ISSN 0028-1298 R&D Projects: GA AV ČR(CZ) IAA500110905 Institutional research plan: CEZ:AV0Z50110509 Keywords : acetylcholine * endplate currents Subject RIV: ED - Physiology Impact factor: 2.631, year: 2009

Torque strength of an endplate welding due to process parameters using a fuel assembling welder

Energy Technology Data Exchange (ETDEWEB)

Koo, Dae-Seo; Kim, Soo-Sung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2008-05-15

As fuel bundles in a PHWR core irradiated, inner pressure in the claddings of the fuel rods increases owing to the outer pressure and fission products of the nuclear fissions. Because of a leak possibility from a welding between a cladding and end plug, this welding part is connected with the safety of nuclear fuel rods. Endplug-cladding welding of nuclear fuel rods in a PHWR takes advantage of a resistance upset butt welding. The weldment between a cladding and endplug is to be sound to prevent a leakage of fission products from a cladding as a UO{sub 2} pellet is irradiated. Weld flash was made from a deformation due to a welding heat and increasing the pressure of the resistivity and resistance from a cladding and endplug. Weld line of a welding interface, microstructure of a weldment and a crystallographic structure change were sources of an iodine induced SCC in a reactor. The soundness of a weldment is important because a weld line connects the leakage of fission products from an operational reactor. In this study, welding specimens were fabricated by a resistance welding method using a bundle fuel welder to measure and analyze the torque of an endplug-endplate welding. The torque of a weldment between an endplug and endplate was measured and analyzed with the welding time. The weldability of a weldment between an endplug and endplate was investigated by a metallographic examination.

Ciguatoxin enhances quantal transmitter release from frog motor nerve terminals.

Science.gov (United States)

Molgó, J.; Comella, J. X.; Legrand, A. M.

1990-01-01

1. Ciguatoxin (CTX), a marine toxin produced by the benthic dinoflagellate Gambierdiscus toxicus, is responsible for a complex endemic disease in man known as ciguatera fish poisoning. In the present study we have investigated the effects of purified CTX extracted for Gymnothorax javanicus moray-eel liver on frog isolated neuromuscular preparations with conventional electrophysiological techniques. 2. CTX (1-2.5 nM) applied to cutaneous pectoris nerve-muscle preparations induced, after a short delay, spontaneous fibrillations of the muscle fibres that could be suppressed with 1 microM tetrodotoxin (TTX) or by formamide to uncouple excitation-contraction. 3. In preparations treated with formamide, CTX (1-2.5 nM) caused either spontaneous or repetitive muscle action potentials (up to frequencies of 60-100 Hz) in response to a single nerve stimulus. Recordings performed at extrajunctional regions of the muscle membrane revealed that during the repetitive firing a prolongation of the repolarizing phase of the action potential occurred. At junctional sites the repetitive action potentials were triggered by repetitive endplate potentials (e.p.ps). 4. CTX (2.5 nM) caused a TTX-sensitive depolarization of the muscle membrane. 5. In junctions equilibrated in solutions containing high Mg2+ + low Ca2+, addition of CTX (1.5 nM) first induced an average increase of 239 +/- 36% in the mean quantal content of e.p.ps. Subsequently CTX reduced and finally blocked nerve-evoked transmitter release irreversibly. 6. CTX (1.5-2.5 nM) increased the frequency of miniature endplate potentials (m.e.p.ps) in junctions bathed either in normal Ringer, low Ca2(+)-high Mg2+ medium or in a nominally Ca2(+)-free solution containing EGTA.2+ Extensive washing with toxin-free solutions did not reverse the effect.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1972891

Characteristics and natural course of vertebral endplate signal (Modic) changes in the Danish general population

DEFF Research Database (Denmark)

Jensen, Tue S; Bendix, Tom; Sorensen, Joan S

2009-01-01

BACKGROUND: Vertebral endplate signal changes (VESC) are more common among patients with low back pain (LBP) and/or sciatica than in people who are not seeking care for back pain. The distribution and characteristics of VESC have been described in people from clinical and non-clinical populations...

A comprehensive model for in-plane and out-of-plane vibration of CANDU fuel endplate rings

Energy Technology Data Exchange (ETDEWEB)

Yu, S.D., E-mail: syu@ryerson.ca; Fadaee, M.

2016-08-01

Highlights: • Proposed an effective method for modelling bending and torsional vibration of CANDU fuel endplate rings. • Applied successfully the thick plate theory to curved structural members by accounting for the transverse shear effect. • The proposed method is computationally more efficient compared to the 3D finite element. - Abstract: In this paper, a comprehensive vibration model is developed for analysing in-plane and out-of-plane vibration of CANDU fuel endplate rings by taking into consideration the effects of in-plane extension in the circumferential and radial directions, shear, and rotatory inertia. The model is based on Reddy’s thick plate theory and the nine-node isoparametric Lagrangian plate finite elements. Natural frequencies of various modes of vibration of circular rings obtained using the proposed method are compared with 3D finite element results, experimental data and results available in the literature. Excellent agreement was achieved.

Presynaptic inhibition of spontaneous acetylcholine release induced by adenosine at the mouse neuromuscular junction.

Science.gov (United States)

De Lorenzo, Silvana; Veggetti, Mariela; Muchnik, Salomón; Losavio, Adriana

2004-05-01

1. At the mouse neuromuscular junction, adenosine (AD) and the A(1) agonist 2-chloro-N(6)-cyclopentyl-adenosine (CCPA) induce presynaptic inhibition of spontaneous acetylcholine (ACh) release by activation of A(1) AD receptors through a mechanism that is still unknown. To evaluate whether the inhibition is mediated by modulation of the voltage-dependent calcium channels (VDCCs) associated with tonic secretion (L- and N-type VDCCs), we measured the miniature end-plate potential (mepp) frequency in mouse diaphragm muscles. 2. Blockade of VDCCs by Cd(2+) prevented the effect of the CCPA. Nitrendipine (an L-type VDCC antagonist) but not omega-conotoxin GVIA (an N-type VDCC antagonist) blocked the action of CCPA, suggesting that the decrease in spontaneous mepp frequency by CCPA is associated with an action on L-type VDCCs only. 3. As A(1) receptors are coupled to a G(i/o) protein, we investigated whether the inhibition of PKA or the activation of PKC is involved in the presynaptic inhibition mechanism. Neither N-(2[p-bromocinnamylamino]-ethyl)-5-isoquinolinesulfonamide (H-89, a PKA inhibitor), nor 1-(5-isoquinolinesulfonyl)-2-methyl-piperazine (H-7, a PKC antagonist), nor phorbol 12-myristate 13-acetate (PHA, a PKC activator) modified CCPA-induced presynaptic inhibition, suggesting that these second messenger pathways are not involved. 4. The effect of CCPA was eliminated by the calmodulin antagonist N-(6-aminohexil)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7) and by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid-acetoxymethyl ester epsilon6TDelta-BM, which suggests that the action of CCPA to modulate L-type VDCCs may involve Ca(2+)-calmodulin. 5. To investigate the action of CCPA on diverse degrees of nerve terminal depolarization, we studied its effect at different external K(+) concentrations. The effect of CCPA on ACh secretion evoked by 10 mm K(+) was prevented by the P/Q-type VDCC antagonist omega-agatoxin IVA. 6. CCPA failed to

Lentiviral-mediated RNAi targeting caspase-3 inhibits apoptosis induced by serum deprivation in rat endplate chondrocytes in vitro

International Nuclear Information System (INIS)

Ding, L.; Wu, J.P.; Xu, G.; Zhu, B.; Zeng, Q.M.; Li, D.F.; Lu, W.

2014-01-01

Current studies find that degenerated cartilage endplates (CEP) of vertebrae, with fewer diffusion areas, decrease nutrient supply and accelerate intervertebral disc degeneration. Many more apoptotic cells have been identified in degenerated than in normal endplates, and may be responsible for the degenerated grade. Previous findings suggest that inhibition of apoptosis is one possible approach to improve disc regeneration. It is postulated that inhibition of CEP cell apoptosis may be responsible for the regeneration of endplates. Caspase-3, involved in the execution phase of apoptosis, is a candidate for regulating the apoptotic process. In the present study, CEP cells were incubated in 1% fetal bovine serum. Activated caspases were detected to identify the apoptotic pathway, and apoptosis was quantified by flow cytometry. Lentiviral caspase-3 short hairpin RNA (shRNA) was employed to study its protective effects against serum deprivation. Silencing of caspase-3 expression was quantified by reverse transcription-polymerase chain reaction and Western blots, and inhibition of apoptosis was quantified by flow cytometry. Serum deprivation increased apoptosis of rat CEP cells through activation of a caspase cascade. Lentiviral caspase-3 shRNA was successfully transduced into CEP cells, and specifically silenced endogenous caspase-3 expression. Surviving cells were protected by the downregulation of caspase-3 expression and activation. Thus, lentiviral caspase-3 shRNA-mediated RNAi successfully silenced endogenous caspase-3 expression, preventing inappropriate or premature apoptosis

Lentiviral-mediated RNAi targeting caspase-3 inhibits apoptosis induced by serum deprivation in rat endplate chondrocytes in vitro

Energy Technology Data Exchange (ETDEWEB)

Ding, L.; Wu, J.P. [Fudan University, Jinshan Hospital, Department of Orthopaedics, Shanghai, China, Department of Orthopaedics, Jinshan Hospital, Fudan University, Shanghai (China); Xu, G. [Fudan University, Jinshan Hospital, Center Laboratory, Shanghai, China, Center Laboratory, Jinshan Hospital, Fudan University, Shanghai (China); Zhu, B.; Zeng, Q.M.; Li, D.F.; Lu, W. [Fudan University, Jinshan Hospital, Department of Orthopaedics, Shanghai, China, Department of Orthopaedics, Jinshan Hospital, Fudan University, Shanghai (China)

2014-05-09

Current studies find that degenerated cartilage endplates (CEP) of vertebrae, with fewer diffusion areas, decrease nutrient supply and accelerate intervertebral disc degeneration. Many more apoptotic cells have been identified in degenerated than in normal endplates, and may be responsible for the degenerated grade. Previous findings suggest that inhibition of apoptosis is one possible approach to improve disc regeneration. It is postulated that inhibition of CEP cell apoptosis may be responsible for the regeneration of endplates. Caspase-3, involved in the execution phase of apoptosis, is a candidate for regulating the apoptotic process. In the present study, CEP cells were incubated in 1% fetal bovine serum. Activated caspases were detected to identify the apoptotic pathway, and apoptosis was quantified by flow cytometry. Lentiviral caspase-3 short hairpin RNA (shRNA) was employed to study its protective effects against serum deprivation. Silencing of caspase-3 expression was quantified by reverse transcription-polymerase chain reaction and Western blots, and inhibition of apoptosis was quantified by flow cytometry. Serum deprivation increased apoptosis of rat CEP cells through activation of a caspase cascade. Lentiviral caspase-3 shRNA was successfully transduced into CEP cells, and specifically silenced endogenous caspase-3 expression. Surviving cells were protected by the downregulation of caspase-3 expression and activation. Thus, lentiviral caspase-3 shRNA-mediated RNAi successfully silenced endogenous caspase-3 expression, preventing inappropriate or premature apoptosis.

Lentiviral-mediated RNAi targeting caspase-3 inhibits apoptosis induced by serum deprivation in rat endplate chondrocytes in vitro

Directory of Open Access Journals (Sweden)

L. Ding

2014-06-01

Full Text Available Current studies find that degenerated cartilage endplates (CEP of vertebrae, with fewer diffusion areas, decrease nutrient supply and accelerate intervertebral disc degeneration. Many more apoptotic cells have been identified in degenerated than in normal endplates, and may be responsible for the degenerated grade. Previous findings suggest that inhibition of apoptosis is one possible approach to improve disc regeneration. It is postulated that inhibition of CEP cell apoptosis may be responsible for the regeneration of endplates. Caspase-3, involved in the execution phase of apoptosis, is a candidate for regulating the apoptotic process. In the present study, CEP cells were incubated in 1% fetal bovine serum. Activated caspases were detected to identify the apoptotic pathway, and apoptosis was quantified by flow cytometry. Lentiviral caspase-3 short hairpin RNA (shRNA was employed to study its protective effects against serum deprivation. Silencing of caspase-3 expression was quantified by reverse transcription-polymerase chain reaction and Western blots, and inhibition of apoptosis was quantified by flow cytometry. Serum deprivation increased apoptosis of rat CEP cells through activation of a caspase cascade. Lentiviral caspase-3 shRNA was successfully transduced into CEP cells, and specifically silenced endogenous caspase-3 expression. Surviving cells were protected by the downregulation of caspase-3 expression and activation. Thus, lentiviral caspase-3 shRNA-mediated RNAi successfully silenced endogenous caspase-3 expression, preventing inappropriate or premature apoptosis.

The non-competitive acetylcholinesterase inhibitor APS12-2 is a potent antagonist of skeletal muscle nicotinic acetylcholine receptors

International Nuclear Information System (INIS)

Grandič, Marjana; Aráoz, Romulo; Molgó, Jordi; Turk, Tom; Sepčić, Kristina; Benoit, Evelyne; Frangež, Robert

2012-01-01

APS12-2, a non-competitive acetylcholinesterase inhibitor, is one of the synthetic analogs of polymeric alkylpyridinium salts (poly-APS) isolated from the marine sponge Reniera sarai. In the present work the effects of APS12-2 were studied on isolated mouse phrenic nerve–hemidiaphragm muscle preparations, using twitch tension measurements and electrophysiological recordings. APS12-2 in a concentration-dependent manner blocked nerve-evoked isometric muscle contraction (IC 50 = 0.74 μM), without affecting directly-elicited twitch tension up to 2.72 μM. The compound (0.007–3.40 μM) decreased the amplitude of miniature endplate potentials until a complete block by concentrations higher than 0.68 μM, without affecting their frequency. Full size endplate potentials, recorded after blocking voltage-gated muscle sodium channels, were inhibited by APS12-2 in a concentration-dependent manner (IC 50 = 0.36 μM) without significant change in the resting membrane potential of the muscle fibers up to 3.40 μM. The compound also blocked acetylcholine-evoked inward currents in Xenopus oocytes in which Torpedo (α1 2 β1γδ) muscle-type nicotinic acetylcholine receptors (nAChRs) have been incorporated (IC 50 = 0.0005 μM), indicating a higher affinity of the compound for Torpedo (α1 2 β1γδ) than for the mouse (α1 2 β1γε) nAChR. Our data show for the first time that APS12-2 blocks neuromuscular transmission by a non-depolarizing mechanism through an action on postsynaptic nAChRs of the skeletal neuromuscular junction. -- Highlights: ► APS12-2 produces concentration-dependent inhibition of nerve-evoked muscle contraction in vitro. ► APS12-2 blocks MEPPs and EPPs at the neuromuscular junction. APS12-2 blocks ACh-activated current in Xenopus oocytes incorporated with Torpedo nAChRs.

Numerical Study on the Structural Performance of Steel Beams with Slant End-plate Connections

Directory of Open Access Journals (Sweden)

Farshad Zahmatkesh

Full Text Available Abstract Thermal effects can be one of the most harmful conditions that any steel structure should expect throughout its service life. To counteract this effect, a new beam, with a capability to dissipate thermally induced axial force by slanting of end-plate connection at both ends, is proposed. The beam was examined in terms of its elastic mechanical behavior under symmetric transverse load in presence of an elevated temperature by means of direct stiffness finite element model. The performance of such connection is defined under two resisting mechanisms; by friction force dissipation between faces of slant connection and by small upward crawling on slant plane. The presented numerical method is relatively easy and useful to evaluate the behavior of the proposed beam of various dimensions at different temperatures. Its applicability is evident through satisfactory results verification with those from experimental, analytical and commercially available finite element software. Based on the good agreement between theoretical and experimental methods, a series of design curves were developed as a safe-practical range for the slant end-plate connections which are depend on the conditions of the connection.

Electrical stimulation of paralyzed vibrissal muscles reduces endplate reinnervation and does not promote motor recovery after facial nerve repair in rats.

Science.gov (United States)

Sinis, Nektarios; Horn, Frauke; Genchev, Borislav; Skouras, Emmanouil; Merkel, Daniel; Angelova, Srebrina K; Kaidoglou, Katerina; Michael, Joern; Pavlov, Stoyan; Igelmund, Peter; Schaller, Hans-Eberhard; Irintchev, Andrey; Dunlop, Sarah A; Angelov, Doychin N

2009-10-01

The outcome of peripheral nerve injuries requiring surgical repair is poor. Recent work has suggested that electrical stimulation (ES) of denervated muscles could be beneficial. Here we tested whether ES has a positive influence on functional recovery after injury and surgical repair of the facial nerve. Outcomes at 2 months were compared to animals receiving sham stimulation (SS). Starting on the first day after end-to-end suture (facial-facial anastomosis), electrical stimulation (square 0.1 ms pulses at 5 Hz at an ex tempore established threshold amplitude of between 3.0 and 5.0V) was delivered to the vibrissal muscles for 5 min a day, 3 times a week. Restoration of vibrissal motor performance following ES or SS was evaluated using the video-based motion analysis and correlated with the degree of collateral axonal branching at the lesion site, the number of motor endplates in the target musculature and the quality of their reinnervation, i.e. the degree of mono- versus poly-innervation. Neither protocol reduced collateral branching. ES did not improve functional outcome, but rather reduced the number of innervated motor endplates to approximately one-fifth of normal values and failed to reduce the proportion of poly-innervated motor endplates. We conclude that ES is not beneficial for recovery of whisker function after facial nerve repair in rats.

Mechanisms of hydrogen sulfide (H2S) action on synaptic transmission at the mouse neuromuscular junction.

Science.gov (United States)

Gerasimova, E; Lebedeva, J; Yakovlev, A; Zefirov, A; Giniatullin, R; Sitdikova, G

2015-09-10

Hydrogen sulfide (H2S) is a widespread gasotransmitter also known as a powerful neuroprotective agent in the central nervous system. However, the action of H2S in peripheral synapses is much less studied. In the current project we studied the modulatory effects of the H2S donor sodium hydrosulfide (NaHS) on synaptic transmission in the mouse neuromuscular junction using microelectrode technique. Using focal recordings of presynaptic response and evoked transmitter release we have shown that NaHS (300 μM) increased evoked end-plate currents (EPCs) without changes of presynaptic waveforms which indicated the absence of NaHS effects on sodium and potassium currents of motor nerve endings. Using intracellular recordings it was shown that NaHS increased the frequency of miniature end-plate potentials (MEPPs) without changing their amplitudes indicating a pure presynaptic effect. Furthermore, NaHS increased the amplitude of end-plate potentials (EPPs) without influencing the resting membrane potential of muscle fibers. L-cysteine, a substrate of H2S synthesis induced, similar to NaHS, an increase of EPC amplitudes whereas inhibitors of H2S synthesis (β-cyano-L-alanine and aminooxyacetic acid) had the opposite effect. Inhibition of adenylate cyclase using MDL 12,330A hydrochloride (MDL 12,330A) or elevation of cAMP level with 8-(4-chlorophenylthio)-adenosine 3',5'-cyclic monophosphate (pCPT-cAMP) completely prevented the facilitatory action of NaHS indicating involvement of the cAMP signaling cascade. The facilitatory effect of NaHS was significantly diminished when intracellular calcium (Ca(2+)) was buffered by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis acetoxymethyl ester (BAPTA-AM) and ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid acetoxymethyl ester (EGTA-AM). Activation of ryanodine receptors by caffeine or ryanodine increased acetylcholine release and prevented further action of NaHS on transmitter release, likely due to

The non-competitive acetylcholinesterase inhibitor APS12-2 is a potent antagonist of skeletal muscle nicotinic acetylcholine receptors

Energy Technology Data Exchange (ETDEWEB)

Grandič, Marjana [Institute of Physiology, Pharmacology and Toxicology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana (Slovenia); Aráoz, Romulo; Molgó, Jordi [CNRS, Institut de Neurobiologie Alfred Fessard, FRC 2118, Laboratoire de Neurobiologie et Développement, UPR 3294, F-91198 Gif-sur-Yvette Cedex (France); Turk, Tom; Sepčić, Kristina [Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000 Ljubljana (Slovenia); Benoit, Evelyne [CNRS, Institut de Neurobiologie Alfred Fessard, FRC 2118, Laboratoire de Neurobiologie et Développement, UPR 3294, F-91198 Gif-sur-Yvette Cedex (France); Frangež, Robert, E-mail: robert.frangez@vf.uni-lj.si [Institute of Physiology, Pharmacology and Toxicology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana (Slovenia)

2012-12-01

APS12-2, a non-competitive acetylcholinesterase inhibitor, is one of the synthetic analogs of polymeric alkylpyridinium salts (poly-APS) isolated from the marine sponge Reniera sarai. In the present work the effects of APS12-2 were studied on isolated mouse phrenic nerve–hemidiaphragm muscle preparations, using twitch tension measurements and electrophysiological recordings. APS12-2 in a concentration-dependent manner blocked nerve-evoked isometric muscle contraction (IC{sub 50} = 0.74 μM), without affecting directly-elicited twitch tension up to 2.72 μM. The compound (0.007–3.40 μM) decreased the amplitude of miniature endplate potentials until a complete block by concentrations higher than 0.68 μM, without affecting their frequency. Full size endplate potentials, recorded after blocking voltage-gated muscle sodium channels, were inhibited by APS12-2 in a concentration-dependent manner (IC{sub 50} = 0.36 μM) without significant change in the resting membrane potential of the muscle fibers up to 3.40 μM. The compound also blocked acetylcholine-evoked inward currents in Xenopus oocytes in which Torpedo (α1{sub 2}β1γδ) muscle-type nicotinic acetylcholine receptors (nAChRs) have been incorporated (IC{sub 50} = 0.0005 μM), indicating a higher affinity of the compound for Torpedo (α1{sub 2}β1γδ) than for the mouse (α1{sub 2}β1γε) nAChR. Our data show for the first time that APS12-2 blocks neuromuscular transmission by a non-depolarizing mechanism through an action on postsynaptic nAChRs of the skeletal neuromuscular junction. -- Highlights: ► APS12-2 produces concentration-dependent inhibition of nerve-evoked muscle contraction in vitro. ► APS12-2 blocks MEPPs and EPPs at the neuromuscular junction. APS12-2 blocks ACh-activated current in Xenopus oocytes incorporated with Torpedo nAChRs.

Clinical and radiological results 6 years after treatment of traumatic thoracolumbar burst fractures with pedicle screw instrumentation and balloon assisted endplate reduction

NARCIS (Netherlands)

Verlaan, Jorrit Jan; Somers, Inne; Dhert, Wouter J A; Oner, F. Cumhur

2015-01-01

Background context  When used to fixate traumatic thoracolumbar burst fractures, pedicle screw constructs may fail in the presence of severe vertebral body comminution as the intervertebral disc can creep through the fractured endplates leading to insufficient anterior column support.

An analysis of the effect of endplates upon the fin keel of a sailing yacht

International Nuclear Information System (INIS)

Andrews, G.T.; Raiskums, C.L.; Keffer, J.F.

1985-01-01

A long-term investigation is presently underway to assess the overall performance of the modern design of fin keels for sailing yachts. An ultimate goal is to determine the specific advantages for such designs with respect to a centre-board configuration with outside ballast. The present preliminary studies were carried out to determine the basic performance of a typical fin keel shape for various values of leeway angle. A second aspect was to determine the effect upon this baseline performance of a number of endplates of varying sizes and shapes. (author)

Adenosine A₁ and A₂A receptor-mediated modulation of acetylcholine release in the mice neuromuscular junction.

Science.gov (United States)

Garcia, Neus; Priego, Mercedes; Obis, Teresa; Santafe, Manel M; Tomàs, Marta; Besalduch, Nuria; Lanuza, M Angel; Tomàs, Josep

2013-07-01

Immunocytochemistry shows that purinergic receptors (P1Rs) type A1 and A2A (A1 R and A2 A R, respectively) are present in the nerve endings at the P6 and P30 Levator auris longus (LAL) mouse neuromuscular junctions (NMJs). As described elsewhere, 25 μm adenosine reduces (50%) acetylcholine release in high Mg(2+) or d-tubocurarine paralysed muscle. We hypothesize that in more preserved neurotransmission machinery conditions (blocking the voltage-dependent sodium channel of the muscle cells with μ-conotoxin GIIIB) the physiological role of the P1Rs in the NMJ must be better observed. We found that the presence of a non-selective P1R agonist (adenosine) or antagonist (8-SPT) or selective modulators of A1 R or A2 A R subtypes (CCPA and DPCPX, or CGS-21680 and SCH-58261, respectively) does not result in any changes in the evoked release. However, P1Rs seem to be involved in spontaneous release (miniature endplate potentials MEPPs) because MEPP frequency is increased by non-selective block but decreased by non-selective stimulation, with A1 Rs playing the main role. We assayed the role of P1Rs in presynaptic short-term plasticity during imposed synaptic activity (40 Hz for 2 min of supramaximal stimuli). Depression is reduced by micromolar adenosine but increased by blocking P1Rs with 8-SPT. Synaptic depression is not affected by the presence of selective A1 R and A2 A R modulators, which suggests that both receptors need to collaborate. Thus, A1 R and A2 A R might have no real effect on neuromuscular transmission in resting conditions. However, these receptors can conserve resources by limiting spontaneous quantal leak of acetylcholine and may protect synaptic function by reducing the magnitude of depression during repetitive activity. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Measuring the absolute disintegration rate of a radioactive gas with a moveable endplate discharge counter (MEP) and theoretical calculation of wall effect

International Nuclear Information System (INIS)

Jaffey, A.H.; Gray, J.; Bentley, W.C.; Lerner, J.L.

1987-09-01

A precision built moveable endplate Geiger-Mueller counter was used to measure the absolute disintegration rate of a beta-emitting radioactive gas. A Geiger-Mueller counter used for measuring gaseous radioactivity has 85 Kr (beta energy, 0.67 MeV). The wall effect calculation is readily extendable to other beta energies

Multiple Actions of Rotenone, an Inhibitor of Mitochondrial Respiratory Chain, on Ionic Currents and Miniature End-Plate Potential in Mouse Hippocampal (mHippoE-14 Neurons

Directory of Open Access Journals (Sweden)

Chin-Wei Huang

2018-05-01

Full Text Available Background/Aims: Rotenone (Rot is known to suppress the activity of complex I in the mitochondrial chain reaction; however, whether this compound has effects on ion currents in neurons remains largely unexplored. Methods: With the aid of patch-clamp technology and simulation modeling, the effects of Rot on membrane ion currents present in mHippoE-14 cells were investigated. Results: Addition of Rot produced an inhibitory action on the peak amplitude of INa with an IC50 value of 39.3 µM; however, neither activation nor inactivation kinetics of INa was changed during cell exposure to this compound. Addition of Rot produced little or no modifications in the steady-state inactivation curve of INa. Rot increased the amplitude of Ca2+-activated Cl- current in response to membrane depolarization with an EC50 value of 35.4 µM; further addition of niflumic acid reversed Rot-mediated stimulation of this current. Moreover, when these cells were exposed to 10 µM Rot, a specific population of ATP-sensitive K+ channels with a single-channel conductance of 18.1 pS was measured, despite its inability to alter single-channel conductance. Under current clamp condition, the frequency of miniature end-plate potentials in mHippoE-14 cells was significantly raised in the presence of Rot (10 µM with no changes in their amplitude and time course of rise and decay. In simulated model of hippocampal neurons incorporated with chemical autaptic connection, increased autaptic strength to mimic the action of Rot was noted to change the bursting pattern with emergence of subthreshold potentials. Conclusions: The Rot effects presented herein might exert a significant action on functional activities of hippocampal neurons occurring in vivo.

Use of a Y-tube conduit after facial nerve injury reduces collateral axonal branching at the lesion site but neither reduces polyinnervation of motor endplates nor improves functional recovery.

Science.gov (United States)

Hizay, Arzu; Ozsoy, Umut; Demirel, Bahadir Murat; Ozsoy, Ozlem; Angelova, Srebrina K; Ankerne, Janina; Sarikcioglu, Sureyya Bilmen; Dunlop, Sarah A; Angelov, Doychin N; Sarikcioglu, Levent

2012-06-01

Despite increased understanding of peripheral nerve regeneration, functional recovery after surgical repair remains disappointing. A major contributing factor is the extensive collateral branching at the lesion site, which leads to inaccurate axonal navigation and aberrant reinnervation of targets. To determine whether the Y tube reconstruction improved axonal regrowth and whether this was associated with improved function. We used a Y-tube conduit with the aim of improving navigation of regenerating axons after facial nerve transection in rats. Retrograde labeling from the zygomatic and buccal branches showed a halving in the number of double-labeled facial motor neurons (15% vs 8%; P facial-facial anastomosis coaptation. However, in both surgical groups, the proportion of polyinnervated motor endplates was similar (≈ 30%; P > .05), and video-based motion analysis of whisking revealed similarly poor function. Although Y-tube reconstruction decreases axonal branching at the lesion site and improves axonal navigation compared with facial-facial anastomosis coaptation, it fails to promote monoinnervation of motor endplates and confers no functional benefit.

Numerical Simulations on the Laser Spot Welding of Zirconium Alloy Endplate for Nuclear Fuel Bundle Assembly

Science.gov (United States)

Satyanarayana, G.; Narayana, K. L.; Boggarapu, Nageswara Rao

2018-03-01

In the nuclear industry, a critical welding process is joining of an end plate to a fuel rod to form a fuel bundle. Literature on zirconium welding in such a critical operation is limited. A CFD model is developed and performed for the three-dimensional non-linear thermo-fluid analysis incorporating buoyancy and Marnangoni stress and specifying temperature dependent properties to predict weld geometry and temperature field in and around the melt pool of laser spot during welding of a zirconium alloy E110 endplate with a fuel rod. Using this method, it is possible to estimate the weld pool dimensions for the specified laser power and laser-on-time. The temperature profiles will estimate the HAZ and microstructure. The adequacy of generic nature of the model is validated with existing experimental data.

Thermal Behaviour of Beams with Slant End-Plate Connection Subjected to Nonsymmetric Gravity Load

Directory of Open Access Journals (Sweden)

Farshad Zahmatkesh

2014-01-01

Full Text Available Research on the steel structures with confining of axial expansion in fixed beams has been quite intensive in the past decade. It is well established that the thermal behaviour has a key influence on steel structural behaviours. This paper describes mechanical behaviour of beams with bolted slant end-plate connection with nonsymmetric gravity load, subjected to temperature increase. Furthermore, the performance of slant connections of beams in steel moment frame structures in the elastic field is investigated. The proposed model proved that this flexible connection system could successfully decrease the extra thermal induced axial force by both of the friction force dissipation among two faces of slant connection and a small upward movement on the slant plane. The applicability of primary assumption is illustrated. The results from the proposed model are examined within various slant angles, thermal and friction factors. It can be concluded that higher thermal conditions are tolerable when slanting connection is used.

Numerical Study of Electrostatic Field Distortion on LPTPC End-Plates based on Bulk Micromegas Modules

Directory of Open Access Journals (Sweden)

Bhattacharya Purba

2018-01-01

Full Text Available The R&D activities for the linear collider TPC (LC-TPC are currently working on the adoption of the micro pattern devices for the gaseous amplification stage. Several beam tests have been carried out at DESY with a 5 GeV electron beam in a 1 T superconducting magnet. We worked on a large prototype TPC with an end-plate that was built, for the first time, using seven resistive bulk Micromegas modules. During experiments, reduced signal sensitivity was observed at the boundary of these modules. Electrostatic field distortion near the module boundaries was considered to be the possible major reason behind these observations. In the present work, we will explore this hypothesis through numerical simulation. Our aim has been to understand the origin of distortions observed close to the edges of the test beam modules and to explore the possibility of using the Garfield simulation framework for investigating a phenomenon as complex as distortion.

Modeling Electric Discharges with Entropy Production Rate Principles

Directory of Open Access Journals (Sweden)

Thomas Christen

2009-12-01

Full Text Available Under which circumstances are variational principles based on entropy production rate useful tools for modeling steady states of electric (gas discharge systems far from equilibrium? It is first shown how various different approaches, as Steenbeck’s minimum voltage and Prigogine’s minimum entropy production rate principles are related to the maximum entropy production rate principle (MEPP. Secondly, three typical examples are discussed, which provide a certain insight in the structure of the models that are candidates for MEPP application. It is then thirdly argued that MEPP, although not being an exact physical law, may provide reasonable model parameter estimates, provided the constraints contain the relevant (nonlinear physical effects and the parameters to be determined are related to disregarded weak constraints that affect mainly global entropy production. Finally, it is additionally conjectured that a further reason for the success of MEPP in certain far from equilibrium systems might be based on a hidden linearity of the underlying kinetic equation(s.

(Modic) signal alterations of vertebral endplates and their correlation to a minimally invasive treatment of lumbar disc herniation using epidural injections

International Nuclear Information System (INIS)

Liphofer, J.P.; Becker, G.T.; Koester, O.; Theodoridis, T.; Schmid, G.

2006-01-01

Purpose: To study the influence of (Modic) signal alterations (SA) of the cartilage endplate (CEP) of vertebrae L3-S1 on the outcome of an in-patient minimally invasive treatment (MIT), using epidural injections on patients with lumbar disc herniation (LDH). Materials and Methods: The MR images of 59 consecutive patients with LDH within segments L3/L4-L5/S1 undergoing in-patient minimally invasive treatment with epidural injections were evaluated in a clinical study. The (Modic) signal alterations of the CEP were recorded using T1- and T2-weighted sagittal images. On the basis of the T2-weighted sagittal images, the extension and distribution of the SA were measured by dividing each CEP into 9 areas. The outcome of the MIT was recorded using the Oswestry Disability Index (ODI) before and after therapy and in a 3-month follow-up. Within a subgroup of patients (n=35), the distribution and extension of the signal alterations were correlated with the development of the ODI. Results: Segments with LDH showed significantly more (p<0.001) SA of the CEP than segments without LDH. Although the extension of the SA was not dependent on sex, it did increase significantly with age (p=0.017). The outcome after MIT did not depend on the sex and age of the patients or on the type od LDH. The SA extension tended to have a negative correlation with the outcome after MIT after 3 months (p=0.071). A significant negative correlation could be established between the SA extension in the central section of the upper endplate and the outcome after 3 months (p=0.019). (orig.)

Neuromuscular Activity of Micrurus laticollaris (Squamata: Elapidae Venom in Vitro

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Alejandro Carbajal-Saucedo

2014-01-01

Full Text Available In this work, we have examined the neuromuscular activity of Micrurus laticollaris (Mexican coral snake venom (MLV in vertebrate isolated nerve-muscle preparations. In chick biventer cervicis preparations, the MLV induced an irreversible concentration- and time-dependent (1–30 µg/mL neuromuscular blockade, with 50% blockade occurring between 8 and 30 min. Muscle contractures evoked by exogenous acetylcholine were completely abolished by MLV, whereas those of KCl were also significantly altered (86% ± 11%, 53% ± 11%, 89% ± 5% and 89% ± 7% for one, three, 10 and 30 µg of venom/mL, respectively; n = 4; p < 0.05. In mouse phrenic nerve-diaphragm preparations, MLV (1–10 µg/mL promoted a slight increase in the amplitude of twitch-tension (3 µg/mL, followed by neuromuscular blockade (n = 4; the highest concentration caused complete inhibition of the twitches (time for 50% blockade = 26 ± 3 min, without exhibiting a previous neuromuscular facilitation. The venom (3 µg/mL induced a biphasic modulation in the frequency of miniature end-plate potentials (MEPPs/min, causing a significant increase after 15 min, followed by a decrease after 60 min (from 17 ± 1.4 (basal to 28 ± 2.5 (t15 and 12 ± 2 (t60. The membrane resting potential of mouse diaphragm preparations pre-exposed or not to d-tubocurarine (5 µg/mL was also significantly less negative with MLV (10 µg/mL. Together, these results indicate that M. laticollaris venom induces neuromuscular blockade by a combination of pre- and post-synaptic activities.

Kinetics, Ca2+ dependence, and biophysical properties of integrin-mediated mechanical modulation of transmitter release from frog motor nerve terminals

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Chen, B. M.; Grinnell, A. D.

1997-01-01

Neurotransmitter release from frog motor nerve terminals is strongly modulated by change in muscle length. Over the physiological range, there is an approximately 10% increase in spontaneous and evoked release per 1% muscle stretch. Because many muscle fibers do not receive suprathreshold synaptic inputs at rest length, this stretch-induced enhancement of release constitutes a strong peripheral amplifier of the spinal stretch reflex. The stretch modulation of release is inhibited by peptides that block integrin binding of natural ligands. The modulation varies linearly with length, with a delay of no more than approximately 1-2 msec and is maintained constant at the new length. Moreover, the stretch modulation persists in a zero Ca2+ Ringer and, hence, is not dependent on Ca2+ influx through stretch activated channels. Eliminating transmembrane Ca2+ gradients and buffering intraterminal Ca2+ to approximately normal resting levels does not eliminate the modulation, suggesting that it is not the result of release of Ca2+ from internal stores. Finally, changes in temperature have no detectable effect on the kinetics of stretch-induced changes in endplate potential (EPP) amplitude or miniature EPP (mEPP) frequency. We conclude, therefore, that stretch does not act via second messenger pathways or a chemical modification of molecules involved in the release pathway. Instead, there is direct mechanical modulation of release. We postulate that tension on integrins in the presynaptic membrane is transduced mechanically into changes in the position or conformation of one or more molecules involved in neurotransmitter release, altering sensitivity to Ca2+ or the equilibrium for a critical reaction leading to vesicle fusion.

Teste de estimulação repetitiva no músculo ancôneo para diagnóstico da miastenia grave: mapeamento da sua área de placa motora Repetitive stimulation test on the anconeus muscle for the diagnosis of myasthenia gravis: the mapping of its motor end-plate area

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Maria das Graças Wanderley S. Coriolano

2007-06-01

Full Text Available OBJETIVO: Mapear a área de placa motora do músculo ancôneo para definir a melhor localização dos eletrodos de registro em testes de estimulação repetitiva (TER no diagnóstico dos distúrbios da transmissão neuromuscular. MÉTODO: Registramos o potencial de ação composto do músculo ancôneo sobre a pele que o recobre, após estimulação do ramo que o inerva. Analisando as formas de onda registradas em cada ponto da pele foi possível definir a área de placa. RESULTADOS: A área de placa motora do ancôneo é uma linha paralela à borda da ulna. O melhor local de colocação do eletrodo "ativo" de registro situa-se cerca de 2 cm distal ao olécrano e 1 cm lateral à borda da ulna. CONCLUSÃO: A realização de TER no músculo ancôneo é simples e bem tolerada. Com a estimulação do ancôneo o antebraço praticamente não se move, sendo o procedimento livre de artefatos de movimento.PURPOSE: To map the motor end-plate area of the anconeus muscle and define the best place for positioning the recording electrodes in repetitive stimulation tests (RST for the diagnosis of neuromuscular transmission disorders. METHOD: The compound muscle action potential of the anconeus was recorded after stimulating the motor branch of the radial nerve that innervates it. By analyzing the waveforms registered at each point of the skin we were able to define the motor end-plate area. RESULTS: The motor end-plate area of the anconeus is a line parallel to the ulna border. The best place for placing the "active" recording electrode is about 2cm distal to the olecranon and 1 cm lateral to the border of the ulna. CONCLUSION: Performing RST in the anconeus muscle is simple and well tolerated. Stimulation of the anconeus almost doesn't move the forearm and the procedure is virtually free of movement artifacts.

[(Modic) signal alterations of vertebral endplates and their correlation to a minimally invasive treatment of lumbar disc herniation using epidural injections].

Science.gov (United States)

Liphofer, J P; Theodoridis, T; Becker, G T; Koester, O; Schmid, G

2006-11-01

To study the influence of (Modic) signal alterations (SA) of the cartilage endplate (CEP) of vertebrae L3-S1 on the outcome of an in-patient minimally invasive treatment (MIT) using epidural injections on patients with lumbar disc herniation (LDH). The MR images of 59 consecutive patients with LDH within segments L3/L4 - L5/S1 undergoing in-patient minimally invasive treatment with epidural injections were evaluated in a clinical study. The (Modic) signal alterations of the CEP were recorded using T1- and T2-weighted sagittal images. On the basis of the T2-weighted sagittal images, the extension and distribution of the SA were measured by dividing each CEP into 9 areas. The outcome of the MIT was recorded using the Oswestry Disability Index (ODI) before and after therapy and in a 3-month follow-up. Within a subgroup of patients (n = 35), the distribution and extension of the signal alterations were correlated with the development of the ODI. Segments with LDH showed significantly more (p < 0.001) SA of the CEP than segments without LDH. Although the extension of the SA was not dependent on sex, it did increase significantly with age (p = 0.017). The outcome after MIT did not depend on the sex and age of the patients nor on the type of LDH. The SA extension tended to have a negative correlation with the outcome after MIT after 3 months (p = 0.071). A significant negative correlation could be established between the SA extension in the central section of the upper endplate and the outcome after 3 months (p = 0.019). 1. Lumbar disc herniation is clearly associated with the prevalence of (Modic) signal alterations. 2. Extensive signal alterations tend to correlate with a negative outcome of an MIT using epidural injections. 3. Such SA in the central portion of the upper CEP correlate significantly with a negative treatment result. 4. The central portion of the upper CEP being extensively affected by (Modic) SA is a negative predictor for the success of a minimally

Neuromuscular activity of Bothrops neuwiedi pauloensis snake venom in mouse nerve-muscle preparations

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A. M. Durigon

2005-03-01

Full Text Available The pharmacological effects of Bothrops neuwiedi pauloensis venom on mouse phrenic nerve-diaphragm (PND preparations were studied. Venom (20 mug/ml irreversibly inhibited indirectly evoked twitches in PND preparations (60 ± 10% inhibition, mean ± SEM; p<0.05; n=6. At 50 mug/ml, the venom blocked indirectly and directly (curarized preparations evoked twitches in mouse hemidiaphragms. In the absence of Ca2+, venom (50 mug/ml, produced partial blockade only after an 80 min incubation, which reached 40.3 ± 7.8% (p<0.05; n=3 after 120 min. Venom (20 mug/ml increased (25 ± 2%, p< 0.05 the frequency of giant miniature end-plate potentials in 9 of 10 end-plates after 30 min and the number of miniature end-plate potentials which was maximum (562 ± 3%, p<0.05 after 120 min. During the same period, the resting membrane potential decreased from - 81 ± 1.4 mV to - 41.3 ± 3.6 mV 24 fibers; p<0.01; n=4 in the end-plate region and from - 77.4 ± 1.4 to -44.6 ± 3.9 mV (24 fibers; p<0.01; n=4 in regions distant from the end-plate. These results indicate that B. n. pauloensis venom acts primarily at presynaptic sites. They also suggest that enzymatic activity may be involved in this pharmacological action.

How the Second Law of Thermodynamics Has Informed Ecosystem Ecology through Its History

Science.gov (United States)

Chapman, E. J.; Childers, D. L.; Vallino, J. J.

2014-12-01

Throughout the history of ecosystem ecology many attempts have been made to develop a general principle governing how systems develop and organize. We reviewed the historical developments that led to conceptualization of several goal-oriented principles in ecosystem ecology and the relationships among them. We focused our review on two prominent principles—the Maximum Power Principle and the Maximum Entropy Production Principle—and the literature that applies to both. While these principles have considerable conceptual overlap and both use concepts in physics (power and entropy), we found considerable differences in their historical development, the disciplines that apply these principles, and their adoption in the literature. We reviewed the literature using Web of Science keyword searches for the MPP, the MEPP, as well as for papers that cited pioneers in the MPP and the MEPP development. From the 6000 papers that our keyword searches returned, we limited our further meta-analysis to 32 papers by focusing on studies with a foundation in ecosystems research. Despite these seemingly disparate pasts, we concluded that the conceptual approaches of these two principles were more similar than dissimilar and that maximization of power in ecosystems occurs with maximum entropy production. We also found that these two principles have great potential to explain how systems develop, organize, and function, but there are no widely agreed upon theoretical derivations for the MEPP or the MPP, possibly hindering their broader use in ecological research. We end with recommendations for how ecosystems-level studies may better use these principles.

Transmitter release in the neuromuscular synapse of the protein kinase C theta-deficient adult mouse.

Science.gov (United States)

Besalduch, Núria; Santafé, Manel M; Garcia, Neus; Gonzalez, Carmen; Tomás, Marta; Tomás, Josep; Lanuza, Maria A

2011-04-01

We studied structural and functional features of the neuromuscular junction in adult mice (P30) genetically deficient in the protein kinase C (PKC) theta isoform. Confocal and electron microscopy shows that there are no differences in the general morphology of the endplates between PKC theta-deficient and wild-type (WT) mice. Specifically, there is no difference in the density of the synaptic vesicles. However, the myelin sheath is not as thick in the intramuscular nerve fibers of the PKC theta-deficient mice. We found a significant reduction in the size of evoked endplate potentials and in the frequency of spontaneous, asynchronous, miniature endplate potentials in the PKC theta-deficient neuromuscular preparations in comparison with the WT, but the mean amplitude of the spontaneous potentials is not different. These changes indicate that PKC theta has a presynaptic role in the function of adult neuromuscular synapses. Copyright © 2010 Wiley-Liss, Inc.

Modic (endplate) changes in the lumbar spine: bone micro-architecture and remodelling.

Science.gov (United States)

Perilli, Egon; Parkinson, Ian H; Truong, Le-Hoa; Chong, Kuan C; Fazzalari, Nicola L; Osti, Orso L

2015-09-01

In the literature, inter-vertebral MRI signal intensity changes (Modic changes) were associated with corresponding histological observations on endplate biopsies. However, tissue-level studies were limited. No quantitative histomorphometric study on bone biopsies has yet been conducted for Modic changes. The aim of this study was to characterise the bone micro-architectural parameters and bone remodelling indices associated with Modic changes. Forty patients suffering from disabling low back pain, undergoing elective spinal surgery, and exhibiting Modic changes on MRI (Modic 1, n = 9; Modic 2, n = 25; Modic 3, n = 6), had a transpedicular vertebral body biopsy taken of subchondral bone. Biopsies were first examined by micro-CT, for 3D morphometric analysis of bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular separation, trabecular number, and structure model index. Then, samples underwent histological analysis, for determination of bone remodelling indices: osteoid surface to bone surface ratio (OS/BS), eroded surface to bone surface (ES/BS) and osteoid surface to eroded surface ratio (OS/ES). Micro-CT analysis revealed significantly higher BV/TV (up to 70% increase, p < 0.01) and Tb.Th (up to +57%, p < 0.01) in Modic 3 biopsies, compared to Modic 1 and 2. Histological analysis showed significantly lower OS/BS in Modic 2 biopsies (more than 28% decrease, p < 0.05) compared to 1 and 3. ES/BS progressively decreased from Modic 1 to 2 to 3, whereas OS/ES progressively increased with significantly higher values in Modic 3 (up to 159% increase, p < 0.05) than in Modic 1 and 2. Significant differences were found in bone micro-architectural parameters and remodelling indices among Modic types. Modic 1 biopsies had evidence of highest bone turnover, possibly due to an inflammatory process; Modic 2 biopsies were consistent with a reduced bone formation/remodelling stage; Modic 3 biopsies suggested a more stable sclerotic phase, with significantly

A parametrization of two-dimensional turbulence based on a maximum entropy production principle with a local conservation of energy

International Nuclear Information System (INIS)

Chavanis, Pierre-Henri

2014-01-01

In the context of two-dimensional (2D) turbulence, we apply the maximum entropy production principle (MEPP) by enforcing a local conservation of energy. This leads to an equation for the vorticity distribution that conserves all the Casimirs, the energy, and that increases monotonically the mixing entropy (H-theorem). Furthermore, the equation for the coarse-grained vorticity dissipates monotonically all the generalized enstrophies. These equations may provide a parametrization of 2D turbulence. They do not generally relax towards the maximum entropy state. The vorticity current vanishes for any steady state of the 2D Euler equation. Interestingly, the equation for the coarse-grained vorticity obtained from the MEPP turns out to coincide, after some algebraic manipulations, with the one obtained with the anticipated vorticity method. This shows a connection between these two approaches when the conservation of energy is treated locally. Furthermore, the newly derived equation, which incorporates a diffusion term and a drift term, has a nice physical interpretation in terms of a selective decay principle. This sheds new light on both the MEPP and the anticipated vorticity method. (paper)

Back pain's association with vertebral end-plate signal changes in sciatica.

Science.gov (United States)

el Barzouhi, Abdelilah; Vleggeert-Lankamp, Carmen L A M; van der Kallen, Bas F; Lycklama à Nijeholt, Geert J; van den Hout, Wilbert B; Koes, Bart W; Peul, Wilco C

2014-02-01

Patients with sciatica frequently experience disabling back pain. One of the proposed causes for back pain is vertebral end-plate signal changes (VESC) as visualized by magnetic resonance imaging (MRI). To report on VESC findings, changes of VESC findings over time, and the correlation between VESC and disabling back pain in patients with sciatica. A randomized clinical trial with 1 year of follow-up. Patients with 6 to 12 weeks of sciatica who participated in a multicenter, randomized clinical trial comparing an early surgery strategy with prolonged conservative care with surgery if needed. Patients were assessed by means of the 100-mm visual analog scale (VAS) for back pain (with 0 representing no pain and 100 the worst pain ever experienced) at baseline and 1 year. Disabling back pain was defined as a VAS score of at least 40 mm. Patients underwent MRI both at baseline and after 1 year follow-up. Presence and change of VESC was correlated with disabling back pain using chi-square tests and logistic regression analysis. At baseline, 39% of patients had disabling back pain. Of the patients with VESC at baseline, 40% had disabling back pain compared with 38% of the patients with no VESC (p=.67). The prevalence of type 1 VESC increased from 1% at baseline to 35% 1 year later in the surgical group compared with an increase from 3% to 11% in the conservative group. The prevalence of type 2 VESC decreased from 40% to 29% in the surgical group while remaining almost stable in the conservative group at 41%. The prevalence of disabling back pain at 1 year was 12% in patients with no VESC at 1 year, 16% in patients with type 1 VESC, 11% in patients with type 2 VESC, and 3% in patients with both types 1 and 2 VESC (p=.36). Undergoing surgery was associated with increase in the extent of VESC (odds ratio [OR], 8.6; 95% confidence interval [CI], 4.7-15.7; psciatica was highly associated with the development of VESC after 1 year. However, in contrast with the intuitive feeling

(Modic) signal alterations of vertebral endplates and their correlation to a minimally invasive treatment of lumbar disc herniation using epidural injections; (Modic-)Signalveraenderungen vertebraler Endplatten und ihr Bezug zu einer minimalinvasiven Injektionstherapie lumbaler Bandscheibenvorfaelle

Energy Technology Data Exchange (ETDEWEB)

Liphofer, J.P.; Becker, G.T.; Koester, O. [Inst. fuer Diagnostische und Interventionelle Radiologie und Nuklearmedizin, St. Josef-Hospital Bochum (Germany); Theodoridis, T. [Klinik fuer Orthopaedie und Unfallchirurgie, St. Josef-Hospital Bochum (Germany); Schmid, G. [Klinik fuer Diagnostische und Interventionelle Radiologie, Johanna-Etienne-Krankenhaus Neuss (Germany)

2006-11-15

Purpose: To study the influence of (Modic) signal alterations (SA) of the cartilage endplate (CEP) of vertebrae L3-S1 on the outcome of an in-patient minimally invasive treatment (MIT), using epidural injections on patients with lumbar disc herniation (LDH). Materials and Methods: The MR images of 59 consecutive patients with LDH within segments L3/L4-L5/S1 undergoing in-patient minimally invasive treatment with epidural injections were evaluated in a clinical study. The (Modic) signal alterations of the CEP were recorded using T1- and T2-weighted sagittal images. On the basis of the T2-weighted sagittal images, the extension and distribution of the SA were measured by dividing each CEP into 9 areas. The outcome of the MIT was recorded using the Oswestry Disability Index (ODI) before and after therapy and in a 3-month follow-up. Within a subgroup of patients (n=35), the distribution and extension of the signal alterations were correlated with the development of the ODI. Results: Segments with LDH showed significantly more (p<0.001) SA of the CEP than segments without LDH. Although the extension of the SA was not dependent on sex, it did increase significantly with age (p=0.017). The outcome after MIT did not depend on the sex and age of the patients or on the type od LDH. The SA extension tended to have a negative correlation with the outcome after MIT after 3 months (p=0.071). A significant negative correlation could be established between the SA extension in the central section of the upper endplate and the outcome after 3 months (p=0.019). (orig.)

Human cartilaginous endplate degeneration is induced by calcium and the extracellular calcium-sensing receptor in the intervertebral disc

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MP Grant

2016-07-01

Full Text Available The cartilaginous endplates (CEPs are thin layers of hyaline cartilage found adjacent to intervertebral discs (IVDs. In addition to providing structural support, CEPs regulate nutrient and metabolic exchange in the disc. In IVD pathogenesis, CEP undergoes degeneration and calcification, compromising nutrient availability and disc cell metabolism. The mechanism(s underlying the biochemical changes of CEP in disc degeneration are currently unknown. Since calcification is often observed in later stages of IVD degeneration, we hypothesised that elevations in free calcium (Ca2+ impair CEP homeostasis. Indeed, our results demonstrated that the Ca2+ content was consistently higher in human CEP tissue with grade of disc degeneration. Increasing the levels of Ca2+ resulted in decreases in the secretion and accumulation of collagens type I, II and proteoglycan in cultured human CEP cells. Ca2+ exerted its effects on CEP matrix protein synthesis through activation of the extracellular calcium-sensing receptor (CaSR; however, aggrecan content was also affected independent of CaSR activation as increases in Ca2+ directly enhanced the activity of aggrecanases. Finally, supplementing Ca2+ in our IVD organ cultures was sufficient to induce degeneration and increase the mineralisation of CEP, and decrease the diffusion of glucose into the disc. Thus, any attempt to induce anabolic repair of the disc without addressing Ca2+ may be impaired, as the increased metabolic demand of IVD cells would be compromised by decreases in the permeability of the CEP.

Ultrashort time-to-echo MRI of the cartilaginous endplate: technique and association with intervertebral disc degeneration

International Nuclear Information System (INIS)

Law, Travis; Anthony, Marina-Portia; Kim, Mina; Khong, Pek-Lan; Chan, Queenie; Samartzis, Dino

2013-01-01

The purpose of this study was to report the feasibility of the ultrashort time-to-echo (UTE) MRI technique to assess cartilaginous endplate (CEP) defects in humans in vivo and to assess their relationship with intervertebral disc (IVD) degeneration. Nine volunteer subjects (mean age=43.9 years; range=22–61 years) were recruited, representing 54 IVDs and 108 CEPs. The subjects underwent T2-weighted and UTE MRI to assess for the presence and severity of IVD degeneration, and for the presence of CEP defects, respectively, from T12 to S1. IVD degeneration was graded according to the Schneiderman et al. classification on T2-weighted MRI. CEP defects were defined on UTE MRI as discontinuity of high signal over four consecutive images and were independently assessed by two observers. Thirty-seven out of 108 (34.3%) CEPs had defects, which mainly occurred at T12/L1, L1/L2 and L4/L5 (P=0.008). Multivariate logistic regression revealed that lower body mass index (P=0.009) and younger (P=0.034) individuals had a decreased likelihood of having CEP defects. A statistically significant association was found to exist between the presence of CEP defects and IVD degeneration (P=0.036). A higher prevalence of degenerated IVDs with CEP defects was found at L4/5 and L5/S1, while degenerated IVDs with no CEP defects were found throughout the whole lumbar region. Mean IVD degeneration scores of the L4/5 and L5/S1 levels with CEP defects were higher in comparison with those with no CEP defects. Our study demonstrates the feasibility of using UTE MRI in humans in vivo to assess the integrity of the CEP. A statistically significant association was found to exist between the presence of CEP defects and IVD degeneration. In the lower lumbar region, more severe degeneration was found to occur in the IVDs with CEP defects than in those without defects.

An electrophysiological study on the effects of Pa-1G (a phospholipase A(2)) from the venom of king brown snake, Pseudechis australis, on neuromuscular function.

Science.gov (United States)

Fatehi, M; Rowan, E G; Harvey, A L

2002-01-01

The effects of Pa-1G, a phospholipase A(2) (PLA(2)) from the venom of the Australian king brown snake (Pseudechis australis) were determined on the release of acetylcholine, muscle resting membrane potential and motor nerve terminal action potential at mouse neuromuscular junction. Intracellular recording from endplate regions of mouse triangularis sterni nerve-muscle preparations revealed that Pa-1G (800 nM) significantly reduced the amplitude of endplate potentials within 10 min exposure. The quantal content of endplate potentials was decreased to 58+/-6% of control after 30 min exposure to 800 nM Pa-1G. The toxin also caused a partial depolarisation of mouse muscle fibres within 60 min exposure. Extracellular recording of action potentials at motor nerve terminals showed that Pa-1G reduced the waveforms associated with both sodium and potassium conductances. To investigate whether this was a direct or indirect effect of the toxin on these ionic currents, whole cell patch clamp experiments were performed using human neuroblastoma (SK-N-SH) cells and B82 mouse fibroblasts stably transfected with rKv1.2. Patch clamp recording experiments confirmed that potassium currents sensitive to alpha-dendrotoxin recorded from B82 cells and sodium currents in SK-N-SH cells were not affected by the toxin. Since neither facilitation of acetylcholine release at mouse neuromuscular junction nor depression of potassium currents in B82 cells has been observed, the apparent blockade of potassium currents at mouse motor nerve endings induced by the toxin is unlikely to be due to a selective block of potassium channels.

The Pixel-TPC. Demonstration of the concept and results

Energy Technology Data Exchange (ETDEWEB)

Lupberger, Michael [Universitaet Bonn (Germany); Collaboration: LCTPC-Deutschland-Collaboration

2016-07-01

A Time Projection Chamber (TPC) is foreseen as tracker for the ILD, one of the two detector concepts at the planned International Linear Collider (ILC). At the TPC endplates, Micromegas or GEMs will be used as gas amplification structure. Besides segmented anodes, also an active endplate with pixel chips, in our experiments the Timepix ASIC, is considered as a readout option. In a photolithographic process a grid has been produced on top of the chip to form a so called InGrid, which is a Micromegas-like gas amplification structure. Several thousand InGrids are necessary to equip a complete TPC endplate. For demonstration of the concept, three endplate modules have been built with a total of 160 InGrids covering an active area of about 300 cm{sup 2}. To read out the 10.5 million channels, the Timepix ASIC was implemented in a general readout system. A dedicated powering scheme, DAQ and online event display were developed by our group. The feasibility of the Pixel-TPC could be proven in a test beam campaign at DESY early 2015. The data has partly been analysed and shows the potential of this new type of detector. An overview of the developments necessary to build the detector is presented followed by impressions from the test beam and some of the results from the data analysis.

Lumbar internal disc derangement in patients with chronic low back pain: diagnostic value of the MR imaging findings as compared with provoked discography as the standard

Energy Technology Data Exchange (ETDEWEB)

Park, Hyeon Seon; Park, Jee Young; Lee, Sang Ho; Ahn, Yong [Wooridul spine Hospital, Seoul (Korea, Republic of); Lee, Sang Yeun [Puchon Daesung Hospital, Puchon (Korea, Republic of)

2006-04-15

The aim of this study was to evaluate the diagnostic value of the MR imaging findings with provoked discography used as the standard for painful lumbar disc derangement. Two hundred patients (412 discs), (age rang: 21-77 year), with chronic low back pain underwent MRI and provoked discography. We evaluated the MRI T2-WI findings such as disc degeneration, high-Intensity zones and endplate abnormalities. Subsequently, provocative discography was independently performed with using MR imaging, and a painful disc was defined when moderate to severe and concordant pain was provoked. We calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the MRI findings with using provoked discography as the standard. 400 discs showed abnormal findings such as disc degeneration, HIZ and endplate abnormalities on the T2-WI images. 12 discs showed normal finding. HIZ or endplate abnormalities were always combined with disc degeneration. The prevalence of each findings were disc degeneration (400 discs: 97.1%), HIZ (111 discs: 26.9%), type I endplate abnormalities (34 discs: 8.3%), type II endplate abnormalities (75 discs: 18.2%), the combined findings of HIZ and type I endplate abnormalities (2 discs: 0.5%) and the combined findings of HIZ and type II endplate abnormalities (7 discs: 1.7%). The disc degeneration showed high sensitivity (99.5%) and low specificity (5.0%), so only the NPV (91.7%) was significant, and not the PPV (47.8%). Each findings of HIZ (sensitivity, 36.5%, specificity, 81.4%; PPV, 63.18%; NPV, 59.5%), type I endplate abnormalities (11.0%, 94.1%, 61.8% and 54.8%, respectively), type II endplate abnormalities (19.8%, 83.2%, 50.7% and 54.3%, respectively), the combined findings of HIZ and type I endplate abnormalities (0.5%, 99.6%, 50.0% and 53.4%, respectively) and the combined findings of HIZ and type II endplate abnormalities (26.0%, 99.1%, 71.4% and 53.8%, respectively) show high specificity, but low

Lumbar internal disc derangement in patients with chronic low back pain: diagnostic value of the MR imaging findings as compared with provoked discography as the standard

International Nuclear Information System (INIS)

Park, Hyeon Seon; Park, Jee Young; Lee, Sang Ho; Ahn, Yong; Lee, Sang Yeun

2006-01-01

The aim of this study was to evaluate the diagnostic value of the MR imaging findings with provoked discography used as the standard for painful lumbar disc derangement. Two hundred patients (412 discs), (age rang: 21-77 year), with chronic low back pain underwent MRI and provoked discography. We evaluated the MRI T2-WI findings such as disc degeneration, high-Intensity zones and endplate abnormalities. Subsequently, provocative discography was independently performed with using MR imaging, and a painful disc was defined when moderate to severe and concordant pain was provoked. We calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the MRI findings with using provoked discography as the standard. 400 discs showed abnormal findings such as disc degeneration, HIZ and endplate abnormalities on the T2-WI images. 12 discs showed normal finding. HIZ or endplate abnormalities were always combined with disc degeneration. The prevalence of each findings were disc degeneration (400 discs: 97.1%), HIZ (111 discs: 26.9%), type I endplate abnormalities (34 discs: 8.3%), type II endplate abnormalities (75 discs: 18.2%), the combined findings of HIZ and type I endplate abnormalities (2 discs: 0.5%) and the combined findings of HIZ and type II endplate abnormalities (7 discs: 1.7%). The disc degeneration showed high sensitivity (99.5%) and low specificity (5.0%), so only the NPV (91.7%) was significant, and not the PPV (47.8%). Each findings of HIZ (sensitivity, 36.5%, specificity, 81.4%; PPV, 63.18%; NPV, 59.5%), type I endplate abnormalities (11.0%, 94.1%, 61.8% and 54.8%, respectively), type II endplate abnormalities (19.8%, 83.2%, 50.7% and 54.3%, respectively), the combined findings of HIZ and type I endplate abnormalities (0.5%, 99.6%, 50.0% and 53.4%, respectively) and the combined findings of HIZ and type II endplate abnormalities (26.0%, 99.1%, 71.4% and 53.8%, respectively) show high specificity, but low

Involvement of neurotrophin-3 (NT-3) in the functional elimination of synaptic contacts during neuromuscular development.

Science.gov (United States)

Garcia, Neus; Santafé, Manel M; Tomàs, Marta; Lanuza, Maria A; Besalduch, Nuria; Tomàs, Josep

2010-04-05

Confocal immunohistochemistry shows that neurotrophin-3 (NT-3) and its receptor tropomyosin-related tyrosin kinase C (trkC) are present in both neonatal (P6) and adult (P45) mouse motor nerve terminals in neuromuscular junctions (NMJ) colocalized with several synaptic proteins. NT-3 incubation (1-3h, in the range 10-200ng/ml) does not change the size of the evoked and spontaneous endplate potentials at P45. However, NT-3 (1h, 100ng/ml) strongly potentiates evoked ACh release from the weak (70%) and the strong (50%) axonal inputs on dually innervated postnatal endplates (P6) but not in the most developed postnatal singly innervated synapses at P6. The present results indicate that NT-3 has a role in the developmental mechanism that eliminates redundant synapses though it cannot modulate synaptic transmission locally as the NMJ matures.

Presynaptic congenital myasthenic syndrome with a homozygous sequence variant in LAMA5 combines myopia, facial tics, and failure of neuromuscular transmission.

Science.gov (United States)

Maselli, Ricardo A; Arredondo, Juan; Vázquez, Jessica; Chong, Jessica X; Bamshad, Michael J; Nickerson, Deborah A; Lara, Marian; Ng, Fiona; Lo, Victoria L; Pytel, Peter; McDonald, Craig M

2017-08-01

Defects in genes encoding the isoforms of the laminin alpha subunit have been linked to various phenotypic manifestations, including brain malformations, muscular dystrophy, ocular defects, cardiomyopathy, and skin abnormalities. We report here a severe defect of neuromuscular transmission in a consanguineous patient with a homozygous variant in the laminin alpha-5 subunit gene (LAMA5). The variant c.8046C>T (p.Arg2659Trp) is rare and has a predicted deleterious effect. The affected individual, who also carries a rare homozygous sequence variant in LAMA1, had muscle weakness, myopia, and facial tics. Magnetic resonance imaging of brain showed mild volume loss and periventricular T2 prolongation. Repetitive nerve stimulation revealed 50% decrement of compound muscle action potential amplitudes and 250% facilitation immediately after exercise, Endplate studies identified a profound reduction of the endplate potential quantal content and endplates with normal postsynaptic folding that were denuded or partially occupied by small nerve terminals. Expression studies revealed that p.Arg2659Trp caused decreased binding of laminin alpha-5 to SV2A and impaired laminin-521 cell-adhesion and cell projection support in primary neuronal cultures. In summary, this report describing severe neuromuscular transmission failure in a patient with a LAMA5 mutation expands the list of phenotypes associated with defects in genes encoding alpha-laminins. © 2017 Wiley Periodicals, Inc.

Distribution of MRI signal alterations of the cartilage endplate in pre-operated patients with special focus on recurrent lumbar disc herniation

International Nuclear Information System (INIS)

Becker, G.T.; Liphofer, J.; Koester, O.; Willburger, R.E.; Schmid, G.

2006-01-01

Purpose: To study the location of (Modic) MR signal alterations (SA) of the cartilage endplate (CEP) in pre- and non-operated segments L3-S1 with special focus on the presence of recurrent lumbar disc herniation (RLDH). Materials and Methods: In a retrospective study the MR images of vertebrae L3-S1 of 65 consecutive patients with a history of microdiscectomy were evaluated. Of the 190 segments studied, 67 were pre-operated. These were divided into a group with recurrent lumbar disc herniation (RLDH) (n=19) and a group without evidence of RLDH (n=48). Non-operated segments (n=123) were also considered as a separate group. In these three groups the prevalence of different Modic types was determined using the sag. T1- and T2-weighted images, and, in particular, the distribution of SA at the upper and lower CEP was examined by evaluating the sag. T2-weighted images. In order to achieve this, each CEP was divided into nine regions. Results: Pre-operated segments showed significantly more frequent (p<0.001) and more expansive (p<0.001) SA than non-operated segments. Non-operated segments showed SA less frequently in the central region of both upper and lower CEP (p=0.056 and p=0.015, respectively). In operated segments without RLDH, the upper CEP had significantly more SA on the operation side than in the mid-sagittal and contra-lateral regions (p=0.016, p=0.037) and significantly more on the operation side of the lower CEP than in the contra-lateral region (p=0.027). Operated segments with RLDH did not show an emphasis of SA on the operation side. In this group SA occurred significantly more often in the central and ventral mid-sagittal regions of the upper CEP than in the preoperated segments without RLDH. (orig.)

Conduction velocity of action potentials measured from unidimensional latency-topography in human and frog skeletal muscle fibers.

Science.gov (United States)

Homma, S; Nakajima, Y; Hayashi, K; Toma, S

1986-01-01

Conduction of an action potential along skeletal muscle fibers was graphically displayed by unidimensional latency-topography, UDLT. Since the slopes of the equipotential line were linear and the width of the line was constant, it was possible to calculate conduction velocity from the slope. To determine conduction direction of the muscle action potential elicited by electric stimulation applied directly to the muscle, surface recording electrodes were placed on a two-dimensional plane over a human muscle. Thus a bi-dimensional topography was obtained. Then, twelve or sixteen surface electrodes were placed linearly along the longitudinal direction of the action potential conduction which was disclosed by the bi-dimensional topography. Thus conduction velocity of muscle action potential in man, calculated from the slope, was for m. brachioradialis, 3.9 +/- 0.4 m/s; for m. biceps brachii, 3.6 +/- 0.2 m/s; for m. sternocleidomastoideus, 3.6 +/- 0.4 m/s. By using a tungsten microelectrode to stimulate the motor axons, a convex-like equipotential line of an action potential in UDLT was obtained from human muscle fibers. Since a similar pattern of UDLT was obtained from experiments on isolated frog muscles, in which the muscle action potential was elicited by stimulating the motor axon, it was assumed that the maximum of the curve corresponds to the end-plate region, and that the slopes on both sides indicate bi-directional conduction of the action potential.

The effect of radio-frequency self bias on ion acceleration in expanding argon plasmas in helicon sources

Science.gov (United States)

Wiebold, Matthew D.

Time-averaged plasma potential differences up to ˜ 165 V over several hundred Debye lengths are observed in low pressure (pn floating potential for argon (Vp ≈ 5kTe/e). In the capacitive mode, the ion acceleration is not well described by an ambipolar relation. The accelerated population decay is consistent with that predicted by charge-exchange collisions. Grounding the upstream endplate increases the self-bias voltage compared to a floating endplate. In the inductive and helicon modes, the ion acceleration more closely follows an ambipolar relation, a result of decreased capacitive coupling due to the decreased RF skin depth. The scaling of the potential gradient with the argon flow rate, magnetic field and RF power are investigated, with the highest potential gradients observed for the lowest flow rates in the capacitive mode. The magnitude of the self-bias voltage agrees well with that predicted for RF sheaths. Use of the self-bias effect in a plasma thruster is explored, possibly for a low thrust, high specific impulse mode in a multi-mode helicon thruster. This work could also explain similar potential gradients in expanding helicon plasmas that are ascribed to double layer formation in the literature.

Cartilage of the Intervertebral Disc Eng-Plate, A Histological, Histochemical, Fine Structure Study.

Science.gov (United States)

1982-08-01

degeneration (Nachemson et al., 1970). These and related studies consider the end-plates to be composed of hyaline cartilage and thus homologues of articular...results of this study in rhesus indicate, that while present, the cartilage of the end-plate is quite different in structure and presumably...HZSTOLO6ZCAL,-ETCfU) I AUG 82 N 5 NUSSBAUM IUNCLASSIFDATRL8R-1222NL.rnximommmB~iIEND2 AFAMRL-TR-81 - 122 " CARTILAGE OF THE INTERVERTEBRAL DISC END-PLATE A

MRI of transforaminal lumbar interbody fusion: imaging appearance with and without the use of human recombinant bone morphogenetic protein-2 (rhBMP-2)

Energy Technology Data Exchange (ETDEWEB)

Fox, Michael G.; Goldberg, Judd M.; Gaskin, Cree M.; Barr, Michelle S.; Alford, Bennett [University of Virginia, Department of Radiology and Medical Imaging, Charlottesville, VA (United States); Patrie, James T. [University of Virginia, Department of Public Health Sciences, Charlottesville, VA (United States); Shen, Francis H. [University of Virginia, Department of Orthopedic Surgery, Charlottesville, VA (United States)

2014-09-15

To describe the vertebral endplate and intervertebral disc space MRI appearance following TLIF, with and without the use of rhBMP-2, and to determine if the appearance is concerning for discitis/osteomyelitis. After institutional review board approval, 116 TLIF assessments performed on 75 patients with rhBMP-2 were retrospectively and independently reviewed by five radiologists and compared to 73 TLIF assessments performed on 45 patients without rhBMP-2. MRIs were evaluated for endplate signal, disc space enhancement, disc space fluid, and abnormal paraspinal soft tissue. Endplate edema-like signal was reported when T1-weighted hypointensity, T2-weighted hyperintensity, and endplate enhancement were present. Subjective concern for discitis/osteomyelitis on MRI was graded on a five-point scale. Generalized estimating equation binomial regression model analysis was performed with findings correlated with rhBMP-2 use, TLIF level, graft type, and days between TLIF and MRI. The rhBMP-2 group demonstrated endplate edema-like signal (OR 5.66; 95 % CI [1.58, 20.24], p = 0.008) and disc space enhancement (OR 2.40; 95 % CI [1.20, 4.80], p = 0.013) more often after adjusting for the TLIF level, graft type, and the number of days following TLIF. Both groups had a similar temporal distribution for endplate edema-like signal but disc space enhancement peaked earlier in the rhBMP-2 group. Disc space fluid was only present in the rhBMP-2 group. Neither group demonstrated abnormal paraspinal soft tissue and discitis/osteomyelitis was not considered likely in any patient. Endplate edema-like signal and disc space enhancement were significantly more frequent and disc space enhancement developed more rapidly following TLIF when rhBMP-2 was utilized. The concern for discitis/osteomyelitis was similar and minimal in both groups. (orig.)

Interaction of glutamate- and adenosine-induced decrease of acetylcholine quantal release at frog neuromuscular junction

Czech Academy of Sciences Publication Activity Database

Adámek, S.; Shakirzyanova, V.; Malomouzh, A. I.; Naumenko, N. V.; Vyskočil, František

2010-01-01

Roč. 59, č. 5 (2010), s. 803-810 ISSN 0862-8408 R&D Projects: GA AV ČR(CZ) IAA500110905; GA ČR GA202/09/0806 Institutional research plan: CEZ:AV0Z50110509 Keywords : Endplate potentials * Guanylyl cyclase Subject RIV: ED - Physiology Impact factor: 1.646, year: 2010

Effect of Interbody Fusion on the Remaining Discs of the Lumbar Spine in Subjects with Disc Degeneration.

Science.gov (United States)

Ryu, Robert; Techy, Fernando; Varadarajan, Ravikumar; Amirouche, Farid

2016-02-01

To study effects (stress loads) of lumbar fusion on the remaining segments (adjacent or not) of the lumbar spine in the setting of degenerated adjacent discs. A lumbar spine finite element model was built and validated. The full model of the lumbar spine was a parametric finite element model of segments L 1-5 . Numerous hypothetical combinations of one-level lumbar spine fusion and one-level disc degeneration were created. These models were subjected to 10 Nm flexion and extension moments and the stresses on the endplates and consequently on the intervertebral lumbar discs measured. These values were compared to the stresses on healthy lumbar spine discs under the same load and fusion scenarios. Increased stress at endplates was observed only in the settings of L4-5 fusion and L3-4 disc degeneration (8% stress elevation at L2,3 in flexion or extension, and 25% elevation at L3,4 in flexion only). All other combinations showed less endplate stress than did the control model. For fusion at L3-4 and degeneration at L4-5 , the stresses in the endplates at the adjacent level inferior to the fused disc decreased for both loading disc height reductions. Stresses in flexion decreased after fusion by 29.5% and 25.8% for degeneration I and II, respectively. Results for extension were similar. For fusion at L2-3 and degeneration at L4-5 , stresses in the endplates decreased more markedly at the degenerated (30%), than at the fused level (14%) in the presence of 25% disc height reduction and 10 Nm flexion, whereas in extension stresses decreased more at the fused (24.3%) than the degenerated level (5.86%). For fusion at L3-4 and degeneration at L2-3 , there were no increases in endplate stress in any scenario. For fusion at L4-5 and degeneration at L3-4 , progression of degeneration from I to II had a significant effect only in flexion. A dramatic increase in stress was noted in the endplates of the degenerated disc (L3-4 ) in flexion for degeneration II. Stresses are greater

3D Ultrashort TE MRI for Evaluation of Cartilaginous Endplate of Cervical Disk In Vivo: Feasibility and Correlation With Disk Degeneration in T2-Weighted Spin-Echo Sequence.

Science.gov (United States)

Kim, Yeo Ju; Cha, Jang Gyu; Shin, Yoon Sang; Chaudhari, Akshay S; Suh, Young Ju; Hwan Yoon, Seung; Gold, Garry E

2018-05-01

The purpose of this study was to evaluate the feasibility of 3D ultrashort TE (UTE) MRI in depicting the cartilaginous endplate (CEP) and its abnormalities and to investigate the association between CEP abnormalities and disk degeneration on T2-weighted spin-echo (SE) MR images in cervical disks in vivo. Eight healthy volunteers and 70 patients were examined using 3-T MRI with the 3D UTE cones trajectory technique (TR/TE, 16.1/0.032, 6.6). In the volunteer study, quantitative and qualitative assessments of CEP depiction were conducted for the 3D UTE and T2-weighted SE imaging. In the patient study, CEP abnormalities were analyzed. Intersequence agreement between the images obtained with the first-echo 3D UTE sequence and the images created by subtracting the second-echo from the first-echo 3D UTE sequence (subtracted 3D UTE) and the intraobserver and interobserver agreements for 3D UTE overall were also tested. The CEP abnormalities on the 3D UTE images correlated with the Miyazaki grading of the T2-weighted SE images. In the volunteer study, the CEP was well visualized on 3D UTE images but not on T2-weighted SE images (p evaluation of CEP abnormalities, intersequence agreements were substantial to almost perfect, intraobserver agreements were substantial to almost perfect, and interobserver agreements were moderate to substantial (p T2-weighted SE MRI.

Finite element study of a lumbar intervertebral disc nucleus replacement device

Directory of Open Access Journals (Sweden)

Jessica S Coogan

2016-12-01

Full Text Available Nucleus replacement technologies are a minimally invasive alternative to spinal fusion and total disc replacement that have the potential to reduce pain and restore motion for patients with degenerative disc disease. Finite element modeling can be used to determine the biomechanics associated with nucleus replacement technologies. The current study focuses on a new nucleus replacement device designed as a conforming silicone implant with an internal void. A validated finite element model of the human lumbar L3-L4 motion segment was developed and used to investigate the influence of the nucleus replacement device on spine biomechanics. In addition, the effect of device design changes on biomechanics was determined. A 3D, L3-L4 finite element model was constructed from medical imaging data. Models were created with the normal intact nucleus, the nucleus replacement device, and a solid silicone implant. Probabilistic analysis was performed on the normal model to provide quantitative validation metrics. Sensitivity analysis was performed on the silicone Shore A durometer of the device. Models were loaded under axial compression followed by flexion/extension, lateral bending, or axial rotation. Compressive displacement, endplate stresses, reaction moment, and annulus stresses were determined and compared between the different models. The novel nucleus replacement device resulted in similar compressive displacement, endplate stress, and annulus stress and slightly higher reaction moment compared with the normal nucleus. The solid implant resulted in decreased displacement, increased endplate stress, decreased annulus stress, and decreased reaction moment compared with the novel device. With increasing silicone durometer, compressive displacement decreased, endplate stress increased, reaction moment increased, and annulus stress decreased. Finite element analysis was used to show that the novel nucleus replacement device results in similar biomechanics

[Mechanical and dimensional properties of thermosetting resins for crown (author's transl)].

Science.gov (United States)

Hirasawa, T; Hirano, S; Harashima, I; Hirabayashi, S; Mori, R

1979-10-01

The various mechanical and dimensional properties of seven thermosetting methacrylic resins for crown and one heat-curing methacrylic resin as the control were investigated. The obtained results were as follows. 1. The water sorption, namely amount of sorption water and linear expansion by water sorption of hydrophobic poly-bis-MEPP resins were 50 to 70% of that of the control. But hydrophilic poly-EDMA resins indicated the water sorption about 1 to 1.5 times as much as the control. And a poly-UDMA resin was also hydrophilic as poly-EDMA resins, indicated about 1.3 times as much as the control. 2. The properties of poly-bis-MEPP resins were more excellent than that of poly-EDMA resins especially in the wet condition, at least were equal. 3. A poly-UDMA resin contained so-called organic composite fillers, indicated more excellent properties than other resins on hardness, abrasion resistance, linear coefficient of thermal expansion, compressive strength and bending strength in the dry condition. But, in the wet condition, some of these properties of a poly-UDMA resin were approximately equal to those of other resins.

Excitatory effect of the A2A adenosine receptor agonist CGS-21680 on spontaneous and K+-evoked acetylcholine release at the mouse neuromuscular junction.

Science.gov (United States)

Palma, A G; Muchnik, S; Losavio, A S

2011-01-13

The mechanism of action of the A2A adenosine receptor agonist 2-p-(2-carboxyethyl) phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS-21680) in the facilitation of spontaneous (isotonic and hypertonic condition) and K+-evoked acetylcholine (ACh) release was investigated in the mouse diaphragm muscles. At isotonic condition, the CGS-21680-induced excitatory effect on miniature end-plate potential (MEPP) frequency was not modified in the presence of CdCl2 and in a medium free of Ca2+ (0Ca2+-EGTA), but it was abolished after buffering the rise of intracellular Ca2+ with 1,2-bis-(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetra(acetoxy-methyl) (BAPTA-AM) and when the Ca2+-ATPase inhibitor thapsigargin was used to deplete intracellular Ca2+ stores. CGS-21680 did not have a direct effect on the Ca2+-independent neurotransmitter-releasing machinery, since the modulatory effect on the hypertonic response was also occluded by BAPTA-AM and thapsigargin. CGS-21680 facilitation on K+-evoked ACh release was not altered by the P/Q-type voltage-dependent calcium channel (VDCC) blocker ω-Agatoxin IVA, but it was completely prevented by both, the L-type VDCC blocker nitrendipine (which is known to immobilize their gating charges), or thapsigargin, suggesting that the effects of CGS-21680 on L-type VDCC and thapsigargin-sensitive internal stores are associated. We found that the VDCC pore blocker Cd2+ (2 mM Ca2+ or 0Ca2+-EGTA) failed to affect the CGS-21680 effect in high K+ whereas nitrendipine in 0Ca2+-EGTA+Cd2+ occluded its action. The blockade of Ca2+ release from endoplasmic reticulum with ryanodine antagonized the facilitating effect of CGS-21680 in control and high K+ concentration. It is concluded that, at the mouse neuromuscular junction, activation of A2A receptors facilitates spontaneous and K+-evoked ACh release by an external Ca2+-independent mechanism but that involves mobilization of Ca2+ from internal stores: during spontaneous ACh release

Manual and computerized measurement of coronal vertebral inclination on MRI images: A pilot study

International Nuclear Information System (INIS)

Vrtovec, T.; Likar, B.; Pernuš, F.

2013-01-01

Aim: A pilot study that presents a systematic approach for evaluating the variability of manual and computerized measurements of coronal vertebral inclination (CVI) on images acquired by magnetic resonance imaging (MRI). Materials and methods: Three observers identified the vertebral body corners of 28 vertebrae on two occasions on two-dimensional (2D) coronal MRI cross-sections, which served to evaluate CVI using six manual measurements (superior and inferior tangents, left and right tangents, mid-endplate and mid-wall lines). Computerized measurements were performed by evaluating CVI from the symmetry of vertebral anatomical structures of the same 28 vertebrae in 2D coronal MRI cross-sections and in three-dimensional (3D) MRI images. Results: In terms of standard deviation (SD), the mid-endplate lines proved to be the manual measurements with the lowest intra- (1.0° SD) and interobserver (1.4° SD) variability. The computerized measurements in 3D yielded even lower intra- (0.8° SD) and interobserver (1.3° SD) variability. The strongest inter-method agreement (1.2° SD) was found among lines parallel to vertebral endplates (superior tangents, inferior tangents, mid-endplate lines). The computerized measurements in 3D were most in agreement with the mid-endplate lines (1.9° SD). The estimated intra- and interobserver variabilities of standard Cobb angle measurements were equal to 1.6° SD and 2.5° SD, respectively, for manual measurements, and to 1.1° SD and 1.8° SD, respectively, for computerized measurements. Conclusion: The mid-endplate lines proved to be the most reproducible and reliable manual CVI measurements. Computerized CVI measurements based on the evaluation of the symmetry of vertebral anatomical structures in 3D were more reproducible and reliable than manual measurements

The effects of two phospholipase A2 inhibitors on the neuromuscular blocking activities of homologous phospholipases A2 from the venom of Pseudechis australis, the Australian king brown snake.

Science.gov (United States)

Fatehi, M; Rowan, E G; Harvey, A L

1995-12-01

Previous studies have shown that homologous phospholipases A2 (PLA2) (Pa-3, Pa-9C, Pa-10F and Pa-11) from the venom of the Australian king brown snake, Pseudechis australis, significantly reduce the resting membrane potentials and quantal contents of endplate potentials recorded from endplate regions of mouse triangularis sterni nerve-muscle preparations. It is not clear whether PLA2 activity is essential for their neuromuscular activities. Therefore, pharmacological studies were carried out to determine whether neuromuscular activity of the toxins changed after treatment with the phospholipase A2 inhibitors 7,7-dimethyl-eicosadienoic acid (DEDA) and manoalide. After incubation of the toxins with manoalide (120 nM), or DEDA (50 microM), no PLA2 activity against 1-stearoyl 2-[3H]arachidonoylglycerophosphocholine was detected. After incubation with manoalide and/or DEDA, the toxins did not depolarize muscle fibre membranes up to 60 min after administration. However, manoalide and DEDA had different influences on the inhibitory effect of these toxic enzymes on acetylcholine release from nerve terminals. Manoalide abolished the inhibitory effect of the toxins on evoked release of acetylcholine. In contrast, DEDA was not able to prevent the reduction of quantal content of endplate potentials induced by the toxins. This study provides evidence that the depolarizing action and the inhibitory effect on release of acetylcholine exerted by these toxic PLA2 from king brown snake are independent phenomena. The evidence for this conclusion was that inhibition of enzymatic activity with an arachidonic acid analogue (DEDA) abolished the depolarizing effect of the toxins but not the effects on the quantal release of acetylcholine from mouse motor nerve terminals. The data suggest that the depolarizing effect of these toxins is probably due to the enzymatic activity. Since manoalide interacts with lysine residues of PLA2 polypeptides, and, as shown here, manoalide prevented

Thoracic spine disc-related abnormalities: longitudinal MR imaging assessment

Energy Technology Data Exchange (ETDEWEB)

Girard, Charles J.; Schweitzer, Mark E.; Morrison, William B.; Parellada, Joan A. [TJUH Radiology, Philadelphia, Pennsylvania (United States); Carrino, J.A. [Department of Radiology ASB-1, Harvard Medical School, Brigham and Women' s Hospital, L1, Room 002B, 75 Francis Street, MA 02115, Boston (United States)

2004-04-01

To describe and characterize the temporal changes in disc-related disorders of the thoracic spine using MR imaging. A retrospective longitudinal cohort study was carried out of 40 patients with two sequential thoracic spine MR images at variable intervals. The images were assessed for baseline presence of, new incidence of and changes in disc herniation, degenerative disc disease, endplate marrow signal alteration and Schmorl nodes. The range of follow-up was 4-149 weeks. Baseline presence was: disc herniation, 10% (49/480); degenerative disc disease, 14% (66/480); endplate marrow signal alteration, 2.3% (11/480); Schmorl nodes 9.6% (46/480). Most pre-existing lesions tended to remain unchanged. Herniations showed the most change, tending to improve in 27%. New incidence was: disc herniation, 1.5% (7/480), degenerative disc disease, 2% (10/480); endplate marrow signal alteration, 1.6% (8/480); Schmorl nodes, 2.1% (10/480). Disc degeneration was first visible at an 11-week interval and once established almost never changed over many weeks to months. Endplate signal alterations (Modic changes) were uncommon. Schmorl nodes show no change from baseline for up to 2 1/2 years. All findings predominated in the lower intervertebral levels from T6 to T10. The most prevalent thoracic spine disc-related findings are degeneration and herniation. Disc herniations predominate in the lower segments and are a dynamic phenomenon. Disc degeneration can be rapidly evolving but tends to remain unchanged after occurrence. Endplate marrow signal changes were an uncommon manifestation of thoracic disc disease. Schmorl nodes showed the least change over time. (orig.)

Are the determinants of vertebral endplate changes and severe disc degeneration in the lumbar spine the same? A magnetic resonance imaging study in middle-aged male workers

Directory of Open Access Journals (Sweden)

Korpelainen Raija

2008-04-01

Full Text Available Abstract Background Modic changes are bone marrow lesions visible in magnetic resonance imaging (MRI, and they are assumed to be associated with symptomatic intervertebral disc disease, especially changes located at L5-S1. Only limited information exists about the determinants of Modic changes. The objective of this study was to evaluate the determinants of vertebral endplate (Modic changes, and whether they are similar for Modic changes and severe disc degeneration focusing on L5-S1 level. Methods 228 middle-aged male workers (159 train engineers and 69 sedentary factory workers from northern Finland underwent sagittal T1- and T2-weighted MRI. Modic changes and disc degeneration were analyzed from the scans. The participants responded to a questionnaire including items of occupational history and lifestyle factors. Logistic regression analysis was used to evaluate the associations between selected determinants (age, lifetime exercise, weight-related factors, fat percentage, smoking, alcohol use, lifetime whole-body vibration and Modic type I and II changes, and severe disc degeneration (= grade V on Pfirrmann's classification. Results The prevalences of the Modic changes and severe disc degeneration were similar in the occupational groups. Age was significantly associated with all degenerative changes. In the age-adjusted analyses, only weight-related determinants (BMI, waist circumference were associated with type II changes. Exposure to whole-body vibration, besides age, was the only significant determinant for severe disc degeneration. In the multivariate model, BMI was associated with type II changes at L5-S1 (OR 2.75 per one SD = 3 unit increment in BMI, and vibration exposure with severe disc degeneration at L5-S1 (OR 1.08 per one SD = 11-year increment in vibration exposure. Conclusion Besides age, weight-related factors seem important in the pathogenesis of Modic changes, whereas whole-body vibration was the only significant determinant

Double layer dynamics in a collisionless magnetoplasma

International Nuclear Information System (INIS)

Iizuka, Satoru; Michelsen, P.; Rasmussen, J.J.; Schrittwieser, R.; Hatakeyama, Rikizo; Saeki, Koichi; Sato, Noriyoshi.

1985-01-01

Investigations of double layer dynamics are performed in a Q-machine plasma by applying a positive step potential to a cold end-plate collector. The double layer created at the grounded plasma source just after the pulse is applied propagates towards the collector with the plasma flow speed. Large oscillations occur in the plasma current which is related to a recurring formation and propagation of the double layer. The current is limited during the propagation by a growing negative potential dip formed on the low-potential tail. Similar phenomena appear on the low-potential tail of the stationary double layer formed by applying a potential difference between two plasma sources. (author)

Double layer dynamics in a collisionless magnetoplasma

DEFF Research Database (Denmark)

Iizuka, S.; Michelsen, Poul; Juul Rasmussen, Jens

1985-01-01

Investigations of double layer dynamics are performed in a Q-machine plasma by applying a positive step potential to a cold end-plate collector. The double layer created at the grounded plasma source just after the pulse is applied propagates towards the collector with the plasma flow speed. Large...... oscillations occur in the plasma current which is related to a recurring formation and propagation of the double layer. The current is limited during the propagation by a growing negative potential dip formed on the low-potential tail. Similar phenomena appear on the low-potential tail of the stationary double...... layer formed by applying a potential difference between two plasma sources...

Challenges to IPPC-B permitting at LGU in Macedonia

International Nuclear Information System (INIS)

Nikolov, Marjan

2006-01-01

The debate will soon turn to discussion of the arrangements between the environmental protection administration (both central and local), the LGU and ZELS and businesses in order to implement the Law on environment. Of special importance will be development of environment for IPPC-B permitting at the LGU including all stakeholders. The Ministry of Environment and Physical Planning-MEPP must clarify the interface between the responsibilities of the Environmental Protection Administration and those of the LGU.

Experimental Investigation of a Wing-in-Ground Effect Craft

Directory of Open Access Journals (Sweden)

M. Mobassher Tofa

2014-01-01

Full Text Available The aerodynamic characteristics of the wing-in-ground effect (WIG craft model that has a noble configuration of a compound wing was experimentally investigated and Universiti Teknologi Malaysia (UTM wind tunnel with and without endplates. Lift and drag forces, pitching moment coefficients, and the centre of pressure were measured with respect to the ground clearance and the wing angle of attack. The ground effect and the existence of the endplates increase the wing lift-to-drag ratio at low ground clearance. The results of this research work show new proposed design of the WIG craft with compound wing and endplates, which can clearly increase the aerodynamic efficiency without compromising the longitudinal stability. The use of WIG craft is representing an ambitious technology that will help in reducing time, effort, and money of the conventional marine transportation in the future.

Experimental investigation of a wing-in-ground effect craft.

Science.gov (United States)

Tofa, M Mobassher; Maimun, Adi; Ahmed, Yasser M; Jamei, Saeed; Priyanto, Agoes; Rahimuddin

2014-01-01

The aerodynamic characteristics of the wing-in-ground effect (WIG) craft model that has a noble configuration of a compound wing was experimentally investigated and Universiti Teknologi Malaysia (UTM) wind tunnel with and without endplates. Lift and drag forces, pitching moment coefficients, and the centre of pressure were measured with respect to the ground clearance and the wing angle of attack. The ground effect and the existence of the endplates increase the wing lift-to-drag ratio at low ground clearance. The results of this research work show new proposed design of the WIG craft with compound wing and endplates, which can clearly increase the aerodynamic efficiency without compromising the longitudinal stability. The use of WIG craft is representing an ambitious technology that will help in reducing time, effort, and money of the conventional marine transportation in the future.

Amniotic fluid phthalate levels and male fetal gonad function

DEFF Research Database (Denmark)

Jensen, Morten Søndergaard; Anand-Ivell, Ravinder; Nørgaard-Pedersen, Bent

2015-01-01

metabolite) was not consistently associated with cryptorchidism or hypospadias. However, we observed an 18% higher (95% confidence interval [CI] = 5%-33%) testosterone level, and a 41% lower (-56% to -21%) insulin-like factor 3 level in the highest 5cx-MEPP tertile compared with the lowest. Mono(4-methyl-7...... on the DEHP metabolite indicate possible interference with human male fetal gonadal function. Considering the DiNP metabolite, we cannot exclude (nor statistically confirm) an association with hypospadias and, less strongly, with cryptorchidism....

Development of Ultrasound to Measure In-vivo Dynamic Cervical Spine Intervertebral Disc Mechanics

Science.gov (United States)

2014-01-01

The deformation between C4 and C6 measured by the US probe was affected by bulging of the IVD and soft tissues during compressive loading as...endplates of the vertebrae and cartilaginous endplate of the discs were added to all segments. Figure 28 Coronal views of the updated C4-T1 FEM (a...the ligaments and soft tissue connections that provide stability to the cervical spine FSUs were added (Figures 30 and 31). For the anterior

Nerve terminal contributes to acetylcholine receptor organization at the dystrophic neuromuscular junction of mdx mice.

Science.gov (United States)

Marques, Maria Julia; Taniguti, Ana Paula Tiemi; Minatel, Elaine; Neto, Humberto Santo

2007-02-01

Changes in the distribution of acetylcholine receptors have been reported to occur at the neuromuscular junction of mdx mice and may be a consequence of muscle fiber regeneration rather than the absence of dystrophin. In the present study, we examined whether the nerve terminal determines the fate of acetylcholine receptor distribution in the dystrophic muscle fibers of mdx mice. The left sternomastoid muscle of young (1-month-old) and adult (6-month-old) mdx mice was injected with 60 microl lidocaine hydrochloride to induce muscle degeneration-regeneration. Some mice had their sternomastoid muscle denervated at the time of lidocaine injection. After 10 days of muscle denervation, nerve terminals and acetylcholine receptors were labeled with 4-Di-2-ASP and rhodamine-alpha-bungarotoxin, respectively, for confocal microscopy. In young mdx mice, 75% (n = 137 endplates) of the receptors were distributed in islands. The same was observed in 100% (n = 114 endplates) of the adult junctions. In denervated-regenerated fibers of young mice, the receptors were distributed as branches in 89% of the endplates (n = 90). In denervated-regenerated fibers of adult mice, the receptors were distributed in islands in 100% of the endplates (n = 100). These findings show that nerve-dependent mechanisms are also involved in the changes in receptor distribution in young dystrophic muscles. In older dystrophic muscles, other factors may play a role in receptor distribution.

MR imaging features of hemispherical spondylosclerosis

Energy Technology Data Exchange (ETDEWEB)

Vicentini, Joao R.T.; Martinez-Salazar, Edgar L.; Chang, Connie Y.; Bredella, Miriam A.; Rosenthal, Daniel I.; Torriani, Martin [Massachusetts General Hospital and Harvard Medical School, Division of Musculoskeletal Imaging and Intervention, Department of Radiology, Boston, MA (United States)

2017-10-15

Hemispherical spondylosclerosis (HS) is a rare degenerative entity characterized by dome-shaped sclerosis of a single vertebral body that may pose a diagnostic dilemma. The goal of this study was to describe the MR imaging features of HS. We identified spine radiographs and CT examinations of subjects with HS who also had MR imaging for correlation. Two musculoskeletal radiologists independently assessed sclerosis characteristics, presence of endplate erosions, marrow signal intensity, and disk degeneration (Pfirrmann scale). We identified 11 subjects (six males, five females, mean 48 ± 10 years) with radiographic/CT findings of HS. The most commonly affected vertebral body was L4 (6/11; 55%). On MR imaging, variable signal intensity was noted, being most commonly low on T1 (8/11, 73%) and high on fat-suppressed T2-weighted (8/11, 73%) images. In two subjects, diffuse post-contrast enhancement was seen in the lesion. Moderate disk degeneration and endplate bone erosions adjacent to sclerosis were present in all subjects. Erosions of the opposite endplate were present in two subjects (2/11, 18%). CT data from nine subjects showed the mean attenuation value of HS was 472 ± 96 HU. HS appearance on MR imaging is variable and may not correlate with the degree of sclerosis seen on radiographs or CT. Disk degenerative changes and asymmetric endplate erosions are consistent markers of HS. (orig.)

The post irradiation examination of fuel in support of Bruce A nuclear division fueling with flow program

International Nuclear Information System (INIS)

Montin, J.; Sagat, S.; Day, R.; Novak, J.; Bromfield, H.

1995-01-01

Bruce A Nuclear Division (BAND) units are operating at ∼ 75% of full power, because of the potential of a power pulse in the event of an inlet header break. As a result, BAND is converting to fueling with flow, to eliminate the potential of a power pulse and to allow for full-power operation. Concerns regarding the integrity of the end-of-life (EOL) bundles interacting with the latch at the downstream end of the fuel channel were raised. BAND carried out a test program in which EOL bundles in the upstream position 13 of Unit 2 were cascaded into the downstream latch position 1 of another channel. Six of twelve cascaded bundles and two typical EOL position 13 (benchmark) bundles were selected for post-irradiation examination (PIE). Incipient cracks were found in the assembly welds (endplateto-endcap welds) of all six cascaded bundles. No incipient cracks were found in the benchmark bundles. Metallographic and fractographic examination, along with crack dating, and hydrogen and deuterium analyses, indicated that the incipient cracks were the result of delayed-hydride assisted cracking at the EOL. Consequently, Ontario Hydro changed the design of the outlet shield plug to support all three rings of the fuel bundle, to minimize stress and prevent endplate cracking. Also, an ultrasonic endplate inspection tool (UT) was developed and located in the fuel bay. to inspect fuelbundle endplates for cracks. A second test was done involving a series of four bundle cascades in BAND Unit 4 channels that had new outlet shield plugs. The latch bundles were discharged after a hot shutdown. The cascaded Unit 2 and Unit 4 latch bundles were checked for cracks using the UT. The PIE found incipient cracks or less-than-ideal welds in the assembly welds of fuel elements from Unit 2 (latch-supported fuel bundles) that had been identified by the UT as having incipient cracks. No incipient cracks were found in the assembly welds of fuel elements from Unit 4 (new outlet shield

Development of a new bundle welding technology for CANDU fuels

International Nuclear Information System (INIS)

Kim, Soo Sung; Lee, D. Y.; Goo, D. S.

2010-01-01

The new technology of welding process for fuel bundle of CANDU nuclear fuels is considered important in respect to the soundness of weldments and the improvement of the performance of nuclear fuels during the operation in reactor. The probability of leakage of the fission products is mostly apt to occur at the weldments of fuel bundles, and it is connected directly with the safety and life prediction of the nuclear reactor in operation. The fuel bundles of CANDU nuclear fuels are welded by the electrical resistance method, connecting the endplates and endcaps with fuel rods. Therefore, the purpose of this study of the 2nd year is to select the proper welding parameters and to investigate the characteristics of the full-sized samples using the projection endplates and make some prototype samples for the endplate welding of CANDU nuclear fuels. This study will be also provide the fundamental data for the new design and fabrications of CANDU nuclear fuel bundles

Height gain of vertebral bodies and stabilization of vertebral geometry over one year after vertebroplasty of osteoporotic vertebral fractures

International Nuclear Information System (INIS)

Pitton, Michael B.; Morgen, Nadine; Herber, Sascha; Dueber, Christoph; Drees, Philipp; Boehm, Bertram

2008-01-01

The height gain of vertebral bodies after vertebroplasty and geometrical stability was evaluated over a one-year period. Osteoporotic fractures were treated with vertebroplasty. The vertebral geometry and disc spaces were analysed using reformatted computed tomography (CT) images: heights of the anterior, posterior, and lateral vertebral walls, disc spaces, endplate angles, and minimal endplate distances. Vertebrae were assigned to group I [severe compression (anterior height/posterior height) 0.75). A total of 102 vertebral bodies in 40 patients (12 men, 28 women, age 70.3 ± 9.5) were treated with vertebroplasty and prospectively followed for 12 months. Group I showed a greater benefit compared with group II with respect to anterior height gain (+2.1 ± 1.9 vs +0.7 ± 1.6 mm, P < 0.001), reduction of endplate angle (-3.6 ± 4.2 vs -0.8 ± 2.3 , P < 0.001), and compression index (+0.09 ± 0.11 vs +0.01 ± 0.06, P < 0.001). At one-year follow-up, group I demonstrated preserved anterior height gain (+1.5 ± 2.8 mm, P < 0.015) and improved endplate angle (-3.4 ± 4.9 , P < 0.001). In group II, the vertebral heights returned to and were fixed at the pre-interventional levels. Vertebroplasty provided vertebral height gain over one year, particularly in cases with severe compression. Vertebrae with moderate compression were fixed and stabilized at the pre-treatment level over one year. (orig.)

Electrically induced release of acetylcholine from denervated Schwann cells.

Science.gov (United States)

Dennis, M J; Miledi, R

1974-03-01

1. Focal electrical stimulation of Schwann cells at the end-plates of denervated frog muscles elicited slow depolarizations of up to 30 mV in the muscle fibres. This response is referred to as a Schwann-cell end-plate potential (Schwann-e.p.p.).2. Repeated stimulation sometimes evoked further Schwann-e.p.p.s, but they were never sustained for more than 30 pulses. Successive e.p.p.s varied in amplitude and time course independently of the stimulus.3. The Schwann-e.p.p.s were reversibly blocked by curare, suggesting that they result from a release of acetylcholine (ACh) by the Schwann cells.4. ACh release by electrical stimulation did not seem to occur in quantal form and was not dependent on the presence of calcium ions in the external medium; nor was it blocked by tetrodotoxin.5. Stimulation which caused release of ACh also resulted in extensive morphological disruption of the Schwann cells, as seen with both light and electron microscopy.6. It is concluded that electrical stimulation of denervated Schwann cells causes break-down of the cell membrane and releases ACh, presumably in molecular form.

The Influence of Magnetic Resonance Imaging Findings of Degenerative Disease on Dual-Energy X-ray Absorptiometry Measurements in Middle-Aged Men

International Nuclear Information System (INIS)

Donescu, O.S.; Battie, M.C.; Videman, T.

2007-01-01

Purpose: To examine degenerative features based on magnetic resonance imaging (MRI) measurements at the lumbar spine in relation to dual-energy X-ray absorptiometry (DXA), and to investigate whether bone mineral density (BMD) is reflected in the substitution of bone trabecular structure by fat at the vertebral body level indicated by MRI T1 relaxation time, endplate concavity, and hypertrophic (osteophytes and endplate sclerosis) MRI findings. Material and Methods: The sample for this cross-sectional study was composed of 102 subjects, 35-70 years old, from a population-based cohort. Data collection included DXA in the anterior-posterior projection at the L1-L4 vertebrae and right femoral neck, and MRI of the lumbar spine in the midsagittal plane. Results: Age, vertebral signal intensity, osteophytes, and endplate concavity collectively explained 20% of the variance in spine BMD. Conclusion: The study findings suggest that degenerative findings based on MRI measurements at the lumbar spine have an influence on bone assessment using DXA. Therefore, an overall bone assessment such as DXA might not offer an accurate measure of BMD

Architecture of vagal motor units controlling striated muscle of esophagus: peripheral elements patterning peristalsis?

Science.gov (United States)

Powley, Terry L; Mittal, Ravinder K; Baronowsky, Elizabeth A; Hudson, Cherie N; Martin, Felecia N; McAdams, Jennifer L; Mason, Jacqueline K; Phillips, Robert J

2013-12-01

Little is known about the architecture of the vagal motor units that control esophageal striated muscle, in spite of the fact that these units are necessary, and responsible, for peristalsis. The present experiment was designed to characterize the motor neuron projection fields and terminal arbors forming esophageal motor units. Nucleus ambiguus compact formation neurons of the rat were labeled by bilateral intracranial injections of the anterograde tracer dextran biotin. After tracer transport, thoracic and abdominal esophagi were removed and prepared as whole mounts of muscle wall without mucosa or submucosa. Labeled terminal arbors of individual vagal motor neurons (n=78) in the esophageal wall were inventoried, digitized and analyzed morphometrically. The size of individual vagal motor units innervating striated muscle, throughout thoracic and abdominal esophagus, averaged 52 endplates per motor neuron, a value indicative of fine motor control. A majority (77%) of the motor terminal arbors also issued one or more collateral branches that contacted neurons, including nitric oxide synthase-positive neurons, of local myenteric ganglia. Individual motor neuron terminal arbors co-innervated, or supplied endplates in tandem to, both longitudinal and circular muscle fibers in roughly similar proportions (i.e., two endplates to longitudinal for every three endplates to circular fibers). Both the observation that vagal motor unit collaterals project to myenteric ganglia and the fact that individual motor units co-innervate longitudinal and circular muscle layers are consistent with the hypothesis that elements contributing to peristaltic programming inhere, or are "hardwired," in the peripheral architecture of esophageal motor units. © 2013.

Alpha-event and surface characterisation in segmented true-coaxial HPGe detectors

Energy Technology Data Exchange (ETDEWEB)

Abt, I.; Garbini, L., E-mail: luciagarbini86@gmail.com.mpg.de; Gooch, C.; Irlbeck, S.; Liu, X.; Palermo, M.; Schulz, O.

2017-06-21

A detailed study of alpha interactions on the passivation layer on the end-plate of a true-coaxial high-purity germanium detector is presented. The observation of alpha events on such a surface indicates an unexpectedly thin so-called “effective dead layer” of less than 20 µm thickness. In addition, the influence of the metalisation close to the end-plate on the time evolution of the output pulses is discussed. The results indicate that alpha contamination can result in events which could be mistaken as signals for neutrinoless double beta decay and provide some guidance on how to prevent this.

Ion acceleration in a helicon source due to the self-bias effect

International Nuclear Information System (INIS)

Wiebold, Matt; Sung, Yung-Ta; Scharer, John E.

2012-01-01

Time-averaged plasma potential differences up to 165 V over several hundred Debye lengths are observed in low pressure (p n i ≈ 7 kT e in some cases. RF power up to 500 W at 13.56 MHz is supplied to a half-turn, double-helix antenna in the presence of a nozzle magnetic field, adjustable up to 1 kG. A retarding potential analyzer (RPA) measures the ion energy distribution function (IEDF) and a swept emissive probe measures the plasma potential. Single and double probes measure the electron density and temperature. Two distinct mode hops, the capacitive-inductive (E-H) and inductive-helicon (H-W) transitions, are identified by jumps in density as RF power is increased. In the capacitive (E) mode, large fluctuations of the plasma potential (V p-p ≳140V, V p-p /V p ≈150%) exist at the RF frequency and its harmonics. The more mobile electrons can easily respond to RF-timescale gradients in the plasma potential whereas the inertially constrained ions cannot, leading to an initial flux imbalance and formation of a self-bias voltage between the source and expansion chambers. In the capacitive mode, the ion acceleration is not well described by an ambipolar relation, while in the inductive and helicon modes the ion acceleration more closely follows an ambipolar relation. The scaling of the potential gradient with the argon flow rate and RF power are investigated, with the largest potential gradients observed for the lowest flow rates in the capacitive mode. The magnitude of the self-bias voltage agrees with that predicted for RF self-bias at a wall. Rapid fluctuations in the plasma potential result in a time-dependent axial electron flux that acts to “neutralize” the accelerated ion population, resulting in a zero net time-averaged current through the acceleration region when an insulating upstream boundary condition is enforced. Grounding the upstream endplate increases the self-bias voltage compared to a floating endplate.

Restoration of Motor Defects Caused by Loss of Drosophila TDP-43 by Expression of the Voltage-Gated Calcium Channel, Cacophony, in Central Neurons.

Science.gov (United States)

Lembke, Kayly M; Scudder, Charles; Morton, David B

2017-09-27

Defects in the RNA-binding protein, TDP-43, are known to cause a variety of neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal lobar dementia. A variety of experimental systems have shown that neurons are sensitive to TDP-43 expression levels, yet the specific functional defects resulting from TDP-43 dysregulation have not been well described. Using the Drosophila TDP-43 ortholog TBPH, we previously showed that TBPH-null animals display locomotion defects as third instar larvae. Furthermore, loss of TBPH caused a reduction in cacophony , a Type II voltage-gated calcium channel, expression and that genetically restoring cacophony in motor neurons in TBPH mutant animals was sufficient to rescue the locomotion defects. In the present study, we examined the relative contributions of neuromuscular junction physiology and the motor program to the locomotion defects and identified subsets of neurons that require cacophony expression to rescue the defects. At the neuromuscular junction, we showed mEPP amplitudes and frequency require TBPH. Cacophony expression in motor neurons rescued mEPP frequency but not mEPP amplitude. We also showed that TBPH mutants displayed reduced motor neuron bursting and coordination during crawling and restoring cacophony selectively in two pairs of cells located in the brain, the AVM001b/2b neurons, also rescued the locomotion and motor defects, but not the defects in neuromuscular junction physiology. These results suggest that the behavioral defects associated with loss of TBPH throughout the nervous system can be associated with defects in a small number of genes in a limited number of central neurons, rather than peripheral defects. SIGNIFICANCE STATEMENT TDP-43 dysfunction is a common feature in neurodegenerative diseases, including amyotrophic lateral sclerosis, frontotemporal lobar dementia, and Alzheimer's disease. Loss- and gain-of-function models have shown that neurons are sensitive to TDP-43

The comparative study of radiograph, MRI and pathology in degeneration of lumbar intervertebral disc

International Nuclear Information System (INIS)

Shang Tiesong; Wang Yunzhao

2002-01-01

Objective: To investigate the pathology, and MRI features of the degeneration of lumbar intervertebral discs (IVD). Methods: Thirteen human lumbar spine segments with 31 IVDs were harvested from fresh cadavers. High quality radiographs were taken for all specimens. Five segments with 20 IVD underwent MRl. Then, the radiographic and MRI findings were correlated with corresponding 87 pathologic sections. Results: Variant degeneration was observed in pathologic sections in all 31 IVDs. With MRI T 2 WI images, 20 IVDs showed linear and spotty high signal in the annular fibers, or most of the IVD showed high signal. On pathologic cuts, 22 of 31 IVDs showed infolding of annular fibers, 18 of 31 showed outfolding of annular fibers. On MRI T 1 WI and T 2 WI images, infolding and outfolding of annular fibers were seen as low signal. 20 of 31 IVDs had necrotic debris of cells in the nucleus pulposus. 14 of 20 demonstrated spotty low signal areas on MRI T 2 WI images. 7 Schmorl nodules were found. On pathologic sections Schmorl nodules were seen as IVD tissue protruding into vertebral endplates, they were seen as high signal on T 2 WI images. Two large fissures found on sections were seen as low signal on T 2 WI. Degenerative fibrosis seen on 6 IVD, which showed intermediate signal on T 2 WI images. However, radiographs only demonstrated osteophytes on 3 vertebrae, 7 Schmorl's nodules. Sclerotic, concave and irregular endplates were seen in 11 IVDs, the tatter is the indication of cartilaginous endplate disruption, Conclusion: MRI is very useful in demonstrating the degeneration of IVD, radiograph is able to indirectly show the disappearance of cartilaginous endplate

Prospective evaluation of contrast-enhanced MR imaging after uncomplicated lumbar discography

International Nuclear Information System (INIS)

Carrino, John A.; Swathwood, Todd C.; Morrison, William B.; Glover, J.M.

2007-01-01

Postdiscography infection is an uncommon complication. Magnetic resonance (MR) imaging is often the modality of choice for evaluating spinal infection. Discography entails disc access and fluid injection that could alter the baseline MR imaging appearance of the spine and be confounded for infection. Our purpose was to describe the MR imaging findings of the lumbar spine subsequent to uncomplicated discography and to determine if this may mimic infection. In a prospective cohort study of eight adults (age 22-64 years, mean 45 years) with 22 intradiscal injections, all subjects underwent routine unenhanced and contrast-enhanced MR imaging during the 2-3 week interval postdiscography. A subset of four returned for additional MR imaging during the 4-8 week interval postdiscography. MR images were reviewed for intradiscal, endplate, marrow, and epidural findings and then compared with prediscography examinations. Infection was excluded by clinical documentation. Postdiscography MR imaging showed that almost all levels were similar to baseline prediscography examinations. No levels developed new vertebral marrow edema, fluid-like intradiscal signal, endplate irregularity, or epidural abnormality. Two subjects simulated potential discitis, but these findings were unchanged from prediscography and were related to prior surgery. Uncomplicated lumbar spine discography does not cause MR imaging changes that simulate discitis. (orig.)

Prospective evaluation of contrast-enhanced MR imaging after uncomplicated lumbar discography

Energy Technology Data Exchange (ETDEWEB)

Carrino, John A. [Johns Hopkins University School of Medicine, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Outpatient Center, Baltimore, MD (United States); Swathwood, Todd C. [Blue Ridge Orthopedic Associates, Seneca (United States); Morrison, William B. [Thomas Jefferson University Hospital, Department of Radiology, Philadelphia, PA (United States); Glover, J.M. [Northern Arizona Orthopaedics, Flagstaff, AZ (United States)

2007-04-15

Postdiscography infection is an uncommon complication. Magnetic resonance (MR) imaging is often the modality of choice for evaluating spinal infection. Discography entails disc access and fluid injection that could alter the baseline MR imaging appearance of the spine and be confounded for infection. Our purpose was to describe the MR imaging findings of the lumbar spine subsequent to uncomplicated discography and to determine if this may mimic infection. In a prospective cohort study of eight adults (age 22-64 years, mean 45 years) with 22 intradiscal injections, all subjects underwent routine unenhanced and contrast-enhanced MR imaging during the 2-3 week interval postdiscography. A subset of four returned for additional MR imaging during the 4-8 week interval postdiscography. MR images were reviewed for intradiscal, endplate, marrow, and epidural findings and then compared with prediscography examinations. Infection was excluded by clinical documentation. Postdiscography MR imaging showed that almost all levels were similar to baseline prediscography examinations. No levels developed new vertebral marrow edema, fluid-like intradiscal signal, endplate irregularity, or epidural abnormality. Two subjects simulated potential discitis, but these findings were unchanged from prediscography and were related to prior surgery. Uncomplicated lumbar spine discography does not cause MR imaging changes that simulate discitis. (orig.)

Evaluation of effects of selected factors on inter-vertebral fusion-a simulation study.

Science.gov (United States)

Wang, Xiaobo; Dumas, Geneviève A

2005-04-01

This study simulated the effects of inter-vertebral disc degeneration and bone density distribution on the structural stiffness and strength provided by inter-vertebral fusion. Based on the original and redistributed bone density distributions, the effects of selected factors, including contact area between device/graft and vertebral endplates, endplate conditions, and bone growth capacity were evaluated using a factorial design of experiment. The simulation results suggested that the degeneration of inter-vertebral disc significantly affected the bone density and density distribution in adjacent vertebrae. The mechanical strength immediately after instrumentation is the worst case of device/graft subsidence. After that procedure, bone will adapt itself to the changed loading conditions and therefore reduce the risk of subsidence. A deficiency in structural stiffness immediately after instrumentation could be the "worst-case scenario" depending on the combinations of selected factors. The simulation results demonstrated that the contact area and initial bone density distribution should be considered jointly while estimating the risk of device/graft subsidence. The endplate condition is a secondary factor on the subsidence risk, compared with the contact area and initial bone density distribution.

[Utility of nickel-titanium shape memory alloys of vertebral body reduction fixator with assisted distraction bar].

Science.gov (United States)

Man, Yi; Zheng, Yue-huan; Cao, Peng; Chen, Bo; Zheng, Tao; Sun, Chang-hui; Lu, Jiong

2011-06-07

To test the nickel-titanium (Ni-Ti) shape memory alloys of vertebral body reduction fixator with assisted distraction bar for the treatment of traumatic and osteoporotic vertebral body fracture. A Ni-Ti shape memory alloys of vertebral body reduction fixator with assisted distraction bar was implanted into the compressed fracture specimens through vertebral pedicle with the radiographic monitoring to reduce the collapsed endplate as well as distract the compressed vertebral fracture. Radiographic film and computed tomographic reconstruction technique were employed to evaluate the effects of reduction and distraction. A biomechanic test machine was used to measure the fatigue and the stability of deformation of fixation segments. Relying on the effect of temperature shape memory, such an assembly could basically reduce the collapsed endplate as well as distract the compressed vertebral fracture. And when unsatisfied results of reduction and distraction occurred, its super flexibility could provide additional distraction strength. A Ni-Ti shape memory alloys of vertebral body reduction fixator with assisted distraction bar may provide effective endplate reduction, restore the vertebral height and the immediate biomechanic spinal stability. So the above assembly is indicated for the treatment of traumatic and osteoporotic vertebral body fracture.

Vertebral endplate signal changes (Modic change)

DEFF Research Database (Denmark)

Jensen, Tue Secher; Karppinen, Jaro; Sorensen, Joan S

2008-01-01

/or sciatica and 6% in non-clinical populations. The prevalence was positively associated with age and was negatively associated with the overall quality of the studies. A positive association between VESC and non-specific LBP was found in seven of ten studies from the general, working, and clinical...

Modic type 1 changes. Detection performance of fat-suppressed fluid-sensitive MRI sequences

Energy Technology Data Exchange (ETDEWEB)

Finkenstaedt, Tim; Andreisek, Gustav [University Hospital Zurich (Switzerland). Inst. of Diagnostic and Interventional Radiology; Del Grande, Filippo [Ospedale Regionale di Lugano (Switzerland). Inst. of Diagnostic and Interventional Radiology; Bolog, Nicolae [Phoenix Diagnostic Clinic, Bucharest (Romania); Ulrich, Nils; Tok, Sina [Schulthess Clinic, Zurich (Switzerland). Dept. of Neurosurgery; Kolokythas, Orpheus [Kantonsspital Winterthur (Switzerland). Inst. for Radiology and Nuclear Medicine; Steurer, Johann [University Hospital Zurich (Switzerland). Horten Center for Patient Oriented Research and Knowledge Transfer; Winklhofer, Sebastian [University Hospital Zurich (Switzerland). Inst. of Diagnostic and Interventional Radiology; University Hospital Zurich (Switzerland). Dept. of Neuroradiology; Collaboration: LSOS Study Group

2018-02-15

To assess the performance of fat-suppressed fluid-sensitive MRI sequences compared to T1-weighted (T1w) / T2w sequences for the detection of Modic 1 end-plate changes on lumbar spine MRI. Sagittal T1w, T2w, and fat-suppressed fluid-sensitive MRI images of 100 consecutive patients (consequently 500 vertebral segments; 52 female, mean age 74 ± 7.4 years; 48 male, mean age 71 ± 6.3 years) were retrospectively evaluated. We recorded the presence (yes/no) and extension (i.e., Likert-scale of height, volume, and end-plate extension) of Modic I changes in T1w/T2w sequences and compared the results to fat-suppressed fluid-sensitive sequences (McNemar/Wilcoxon-signed-rank test). Fat-suppressed fluid-sensitive sequences revealed significantly more Modic I changes compared to T1w/T2w sequences (156 vs. 93 segments, respectively; p < 0.001). The extension of Modic I changes in fat-suppressed fluid-sensitive sequences was significantly larger compared to T1w/T2w sequences (height: 2.53 ± 0.82 vs. 2.27 ± 0.79, volume: 2.35 ± 0.76 vs. 2.1 ± 0.65, end-plate: 2.46 ± 0.76 vs. 2.19 ± 0.81), (p < 0.05). Modic I changes that were only visible in fat-suppressed fluid-sensitive sequences but not in T1w/T2w sequences were significantly smaller compared to Modic I changes that were also visible in T1w/T2w sequences (p < 0.05). In conclusion, fat-suppressed fluid-sensitive MRI sequences revealed significantly more Modic I end-plate changes and demonstrated a greater extent compared to standard T1w/T2w imaging.

The MRI appearances of early vertebral osteomyelitis and discitis

International Nuclear Information System (INIS)

Dunbar, J.A.T.; Sandoe, J.A.T.; Rao, A.S.; Crimmins, D.W.; Baig, W.; Rankine, J.J.

2010-01-01

Aim: To describe the magnetic resonance imaging (MRI) appearances in patients with a clinical history suggestive of vertebral osteomyelitis and discitis who underwent MRI very early in their clinical course. Materials and methods: A retrospective review of the database of spinal infections from a spinal microbiological liaison team was performed over a 2 year period to identify cases with clinical features suggestive of spinal infection and an MRI that did not show features typical of vertebral osteomyelitis and discitis. All patients had positive microbiology and a follow up MRI showing typical features of spinal infection. Results: In four cases the features typical of spinal infection were not evident at the initial MRI. In three cases there was very subtle endplate oedema associated with disc degeneration, which was interpreted as Modic type I degenerative endplate change. Intravenous antibiotic therapy was continued prior to repeat MRI examinations. The mean time to the repeat examination was 17 days with a range of 8-22 days. The second examinations clearly demonstrated vertebral osteomyelitis and discitis. Conclusion: Although MRI is the imaging method of choice for vertebral osteomyelitis and discitis in the early stages, it may show subtle, non-specific endplate subchondral changes; a repeat examination may be required to show the typical features.

Ion acceleration in a helicon source due to the self-bias effect

Energy Technology Data Exchange (ETDEWEB)

Wiebold, Matt; Sung, Yung-Ta; Scharer, John E. [University of Wisconsin-Madison, Electrical and Computer Engineering, Madison, Wisconsin 53706 (United States)

2012-05-15

Time-averaged plasma potential differences up to 165 V over several hundred Debye lengths are observed in low pressure (p{sub n} < 1 mTorr) expanding argon plasmas in the Madison Helicon eXperiment (MadHeX). The potential gradient leads to ion acceleration greater than that predicted by ambipolar expansion, exceeding E{sub i} Almost-Equal-To 7 kT{sub e} in some cases. RF power up to 500 W at 13.56 MHz is supplied to a half-turn, double-helix antenna in the presence of a nozzle magnetic field, adjustable up to 1 kG. A retarding potential analyzer (RPA) measures the ion energy distribution function (IEDF) and a swept emissive probe measures the plasma potential. Single and double probes measure the electron density and temperature. Two distinct mode hops, the capacitive-inductive (E-H) and inductive-helicon (H-W) transitions, are identified by jumps in density as RF power is increased. In the capacitive (E) mode, large fluctuations of the plasma potential (V{sub p-p} Greater-Than-Or-Equivalent-To 140V, V{sub p-p}/V{sub p} Almost-Equal-To 150%) exist at the RF frequency and its harmonics. The more mobile electrons can easily respond to RF-timescale gradients in the plasma potential whereas the inertially constrained ions cannot, leading to an initial flux imbalance and formation of a self-bias voltage between the source and expansion chambers. In the capacitive mode, the ion acceleration is not well described by an ambipolar relation, while in the inductive and helicon modes the ion acceleration more closely follows an ambipolar relation. The scaling of the potential gradient with the argon flow rate and RF power are investigated, with the largest potential gradients observed for the lowest flow rates in the capacitive mode. The magnitude of the self-bias voltage agrees with that predicted for RF self-bias at a wall. Rapid fluctuations in the plasma potential result in a time-dependent axial electron flux that acts to 'neutralize' the accelerated ion

Effects of X-irradiation on axonal sprouting induced by botulinum toxin

Energy Technology Data Exchange (ETDEWEB)

Gomez, S; Duchen, L W [National Hospital, London (UK); Hornsey, S [Hammersmith Hospital, London (UK). M.R.C. Cyclotron Unit

1982-01-01

The effect of X-irradiation on axonal sprouting of motor nerves induced by botulinum toxin was examined. Muscles of one leg in the mouse were X-irradiated (15Gy) prior to the injection of a locally paralysing dose of botulinum toxin. It was found that axonal sprouting occurred as expected, but the sprouts remained unmyelinated and many degenerated. Fewer new end-plates were formed, muscles remained more severely atrophied and supersensitive to acetylcholine and recovery of neuromuscular transmission was greatly delayed when compared with the effects of botulinum toxin alone. X-irradiation did not prevent sprouting but, probably by impairing Schwann cell proliferation, altered axon-Schwann cell relationships and prevented the maturation of newly-formed axons and the differentiation of new end-plates.

Influência do lítio no bloqueio neuromuscular produzido pelo atracúrio e pelo cisatracúrio: estudo em preparações nervo frênico-diafragma de rato Influencia del litio en el bloqueo neuromuscular producido por el atracurio y por el cisatracurio: estudio en preparo nervio frénico-diafragma del ratón Influence of lithium on the neuromuscular blockade produced by atracurium and cisatracurium: study on rat phrenic nerve-diaphragm preparations

Directory of Open Access Journals (Sweden)

Samanta Cristina Antoniassi Fernandes

2007-06-01

alteraciones en los potenciales de placa terminal en miniatura mostraron una acción presináptica.BACKGROUND AND OBJECTIVES: Lithium is widely used for the treatment of bipolar disorders and can interact with neuromuscular blockers. There is a controversy about the mechanisms by which it affects neuromuscular transmission and its interaction with neuromuscular blockers. The objective of this study was to evaluate, on the rat diaphragm, the effects of lithium on the muscular response and indirect stimulation, and the possible interaction with neuromuscular blockers. METHODS: Rats weighing between 250 and 300 g were sacrificed under urethane anesthesia. The phrenic nerve-diaphragm preparation was assembled according to the Bulbring technique. The diaphragm was kept under tension, connected to an isometric transducer, and submitted to indirect stimulation with a frequency of 0.1 Hz. The contractions of the diaphragm were registered on a physiograph. The analysis of the amplitude of the muscular responses evaluated: the effects of the isolated drugs: lithium (1.5 mg.mL-1; atracurium (20 µg.mL-1, and cisatracurium (3 µg.mL-1; the lithium-neuromuscular blockers association; and the effects of lithium on the neuromuscular blockade produced by atracurium (35 µg.mL-1 and cisatracurium (5 µg.mL-1. The effects were evaluated before and 45 minutes after the addition of the drugs. The effects of lithium on membrane potentials (MP and miniature end-plate potentials (MEPP were also evaluated. RESULTS: Lithium by itself did not change the amplitude of the muscular responses, but it decreased significantly the neuromuscular blockade produced by atracurium and cisatracurium. It did not change MP and caused an initial increase in MEPP. CONCLUSIONS: Lithium by itself did not compromise neuromuscular transmission and increased the resistance to the effects of atracurium and cisatracurium. It did not show any action on the muscle fiber, and the changes in miniature end-plate potentials

Presynaptic inhibition of spontaneous acetylcholine release mediated by P2Y receptors at the mouse neuromuscular junction.

Science.gov (United States)

De Lorenzo, S; Veggetti, M; Muchnik, S; Losavio, A

2006-09-29

At the neuromuscular junction, ATP is co-released with the neurotransmitter acetylcholine (ACh) and once in the synaptic space, it is degraded to the presynaptically active metabolite adenosine. Intracellular recordings were performed on diaphragm fibers of CF1 mice to determine the action of extracellular ATP (100 muM) and the slowly hydrolysable ATP analog 5'-adenylylimidodiphosphate lithium (betagamma-imido ATP) (30 muM) on miniature end-plate potential (MEPP) frequency. We found that application of ATP and betagamma-imido ATP decreased spontaneous secretion by 45.3% and 55.9% respectively. 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective A(1) adenosine receptor antagonist and alpha,beta-methylene ADP sodium salt (alphabeta-MeADP), which is an inhibitor of ecto-5'-nucleotidase, did not prevent the inhibitory effect of ATP, demonstrating that the nucleotide is able to modulate spontaneous ACh release through a mechanism independent of the action of adenosine. Blockade of Ca(2+) channels by both, Cd(2+) or the combined application of nitrendipine and omega-conotoxin GVIA (omega-CgTx) (L-type and N-type Ca(2+) channel antagonists, respectively) prevented the effect of betagamma-imido ATP, indicating that the nucleotide modulates Ca(2+) influx through the voltage-dependent Ca(2+) channels related to spontaneous secretion. betagamma-Imido ATP-induced modulation was antagonized by the non-specific P2 receptor antagonist suramin and the P2Y receptor antagonist 1-amino-4-[[4-[[4-chloro-6-[[3(or4)-sulfophenyl] amino]-1,3,5-triazin-2-yl]amino]-3-sulfophenyl] amino]-9,10-dihydro-9,10-dioxo-2-anthracenesulfonic acid (reactive blue-2), but not by pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt (PPADS), which has a preferential antagonist effect on P2X receptors. Pertussis toxin and N-ethylmaleimide (NEM), which are blockers of G(i/o) proteins, prevented the action of the nucleotide, suggesting that the effect is mediated by P2Y receptors

Neurotrophin-4 couples to locally modulated ACh release at the end of neuromuscular synapse maturation.

Science.gov (United States)

Garcia, N; Santafe, M M; Tomas, M; Lanuza, M A; Besalduch, N; Tomas, J

2010-01-01

We use immunocytochemistry to show that neurotrophin-4 (NT-4) and its receptor proteins (p75(NTR) and tropomyosin-related tyrosine kinase B) are present in neonatal neuromuscular junctions (NMJ) colocalized with several synaptic markers. NT-4 incubation (1h, in the range 2-12 nM) does not change the size of the endplate potential between P6 and P45. However, extended exposure (3h) to a relatively low dose of NT-4 (2 nM) potentiates ACh release (approx. 70%) in adult but not in neonatal muscles. The present results suggest that the developmental mechanism of axonal competition and neonatal elimination of redundant synapses cannot be modulated by added NT-4. However, this neurotrophin was able to modulate synaptic transmission locally in the adult NMJ.

Do positive MRI findings in the lumbar spine predict future seeking care for low back pain in young teenagers?

DEFF Research Database (Denmark)

Kjær, Per; Leboeuf-Yde, Charlotte; Korsholm, Lars

Background: In MRI studies lumbar disk degeneration and endplate changes have been found in children and adolescents. Such MRI findings appear to be more strongly associated with LBP than in adults. However, this knowledge is mainly based on cross-sectional studies from which no inferences regarded......, nucleus form, annular tears, high intensity zones, bulging, herniation, nerve root compression, endplate changes, Modic changes, and spondylolisthesis). Associations were sought through logistic regression at each lumbar level for boys and girls separately. Statistically significant results were presented......, and annular tears and bulging at L4. Moderate predictors included reduced signal L1 and L4, disk herniation and nerve root compression L4. Other levels and findings showed no statistically significant associations. Interestingly, the areas with the fewest findings showed the strongest associations to seeking...

Numerical study on aerodynamics of banked wing in ground effect

Directory of Open Access Journals (Sweden)

Qing Jia

2016-03-01

Full Text Available Unlike conventional airplane, a WIG craft experiences righting moment and adverse yaw moment in banked turning in ground effect. Numerical simulations are carried out to study the aerodynamics of banked wing in ground effect. Configurations of rectangular wing and delta wing are considered, and performance of endplates and ailerons during banking are also studied. The study shows that righting moment increase nonlinearly with heeling angle, and endplates enhance the righting. The asymmetric aerodynamic distribution along span of wing with heeling angle introduces adverse yaw moment. Heeling in ground effect with small ground clearance increases the vertical aerodynamic force and makes WIG craft climb. Deflections of ailerons introduce lift decrease and a light pitching motion. Delta wing shows advantage in banked turning for smaller righting moment and adverse yaw moment during banking.

Partial view of the Axial Field Spectrometer (version R808)

CERN Multimedia

1980-01-01

The endplates of the cylindrical drift chamber is removed to access the electronics. The vertical Uranium/Scintillator Calorimeter is retracted. The detector on the frontface is a matrix of NaI-crystals for photon spectroscopy

A functional SNP in the regulatory region of the decay-accelerating factor gene associates with extraocular muscle pareses in myasthenia gravis

KAUST Repository

Heckmann, J M; Uwimpuhwe, H; Ballo, R; Kaur, M; Bajic, Vladimir B.; Prince, S

2009-01-01

Complement activation in myasthenia gravis (MG) may damage muscle endplate and complement regulatory proteins such as decay-accelerating factor (DAF) or CD55 may be protective. We hypothesize that the increased prevalence of severe extraocular

Distinction between the extracellular matrix of the nucleus pulposus and hyaline cartilage: a requisite for tissue engineering of intervertebral disc.

Science.gov (United States)

Mwale, F; Roughley, P; Antoniou, J

2004-12-15

Tissue engineering of intervertebral discs (IVD) using mesenchymal stem cells (MSCs) induced to differentiate into a disc-cell phenotype has been considered as an alternative treatment for disc degeneration. However, since there is no unique marker characteristic of discs and since hyaline cartilage and immature nucleus pulposus (NP) possess similar macromolecules in their extracellular matrix, it is currently difficult to recognize MSC conversion to a disc cell. This study was performed to compare the proteoglycan to collagen ratio (measured as GAG to hydroxyproline ratio) in the NP of normal disc to that of the hyaline cartilage of the endplate within the same group of individuals and test the hypothesis that this ratio can be used for in vivo studies to distinguish between a normal NP and hyaline cartilage phenotype. Whole human lumbar spine specimens from fresh cadavers, ranging in age from 12 weeks to 79 years, were used to harvest the IVDs and adjacent endplates. The GAG to hydroxyproline ratio within the NP of young adults is approximately 27:1, whereas the ratio within the hyaline cartilage endplate of the same aged individuals is about 2:1. The production of an extracellular matrix with a high proteoglycan to collagen ratio can be used in vivo to distinguish NP cells from chondrocytes, and could help in identifying a NP-like phenotype in vivo as opposed to a chondrocyte when MSCs are induced to differentiate for tissue engineering of a disc.

Distinction between the extracellular matrix of the nucleus pulposus and hyaline cartilage: a requisite for tissue engineering of intervertebral disc

Directory of Open Access Journals (Sweden)

Mwale F.

2004-12-01

Full Text Available Tissue engineering of intervertebral discs (IVD using mesenchymal stem cells (MSCs induced to differentiate into a disc-cell phenotype has been considered as an alternative treatment for disc degeneration. However, since there is no unique marker characteristic of discs and since hyaline cartilage and immature nucleus pulposus (NP possess similar macromolecules in their extracellular matrix, it is currently difficult to recognize MSC conversion to a disc cell. This study was performed to compare the proteoglycan to collagen ratio (measured as GAG to hydroxyproline ratio in the NP of normal disc to that of the hyaline cartilage of the endplate within the same group of individuals and test the hypothesis that this ratio can be used for in vivo studies to distinguish between a normal NP and hyaline cartilage phenotype. Whole human lumbar spine specimens from fresh cadavers, ranging in age from 12 weeks to 79 years, were used to harvest the IVDs and adjacent endplates. The GAG to hydroxyproline ratio within the NP of young adults is approximately 27:1, whereas the ratio within the hyaline cartilage endplate of the same aged individuals is about 2:1. The production of an extracellular matrix with a high proteoglycan to collagen ratio can be used in vivo to distinguish NP cells from chondrocytes, and could help in identifying a NP-like phenotype in vivo as opposed to a chondrocyte when MSCs are induced to differentiate for tissue engineering of a disc.

Finite element modelling of different CANDU fuel bundle types in various refuelling conditions

International Nuclear Information System (INIS)

Roman, M. R.; Ionescu, D. V.; Olteanu, G.; Florea, S.; Radut, A. C.

2016-01-01

The objective of this paper is to develop a finite element model for static strength analysis of the CANDU standard with 37 elements fuel bundle and the SEU43 with 43 elements fuel bundle design for various refuelling conditions. The computer code, ANSYS7.1, is used to simulate the axial compression in CANDU type fuel bundles subject to hydraulic drag loads, deflection of fuel elements, stresses and displacements in the end plates. Two possible situations for the fuelling machine side stops are considered in our analyses, as follows: the last fuel bundle is supported by the two side stops and a side stop can be blocked therefore, the last fuel bundle is supported by only one side stop. The results of the analyses performed are briefly presented and also illustrated in a graphical form. The finite element model developed in present study is verified against test results for endplate displacement and element bowing obtained from strength tests with fuel bundle string and fuelling machine side-stop simulators. Comparison of ANSYS model predictions with these experimental results led to a very good agreement. Despite the difference in hydraulic load between SEU43 and CANDU standard fuel bundles strings, the maximum stress in the SEU43 endplate is about the same with the maximum stress in the CANDU standard endplate. The comparative assessment reveals that SEU43 fuel bundle is able to withstand high flow rate without showing a significant geometric instability. (authors)

Ergodicity, Maximum Entropy Production, and Steepest Entropy Ascent in the Proofs of Onsager's Reciprocal Relations

Science.gov (United States)

Benfenati, Francesco; Beretta, Gian Paolo

2018-04-01

We show that to prove the Onsager relations using the microscopic time reversibility one necessarily has to make an ergodic hypothesis, or a hypothesis closely linked to that. This is true in all the proofs of the Onsager relations in the literature: from the original proof by Onsager, to more advanced proofs in the context of linear response theory and the theory of Markov processes, to the proof in the context of the kinetic theory of gases. The only three proofs that do not require any kind of ergodic hypothesis are based on additional hypotheses on the macroscopic evolution: Ziegler's maximum entropy production principle (MEPP), the principle of time reversal invariance of the entropy production, or the steepest entropy ascent principle (SEAP).

Experimental Investigation of the End Plate Instability in the Extension of Polymer Melts in a Filament Stretch Rheometer. P.-Y. Longin, H. K. Rasmussen, A. Bach and O. Hassager

DEFF Research Database (Denmark)

Rasmussen, Henrik Koblitz; Longin, Pierre-Yves; Bach, Anders

2001-01-01

We consider here a particular instability, an axis symmetry breaking meniscus instability, that occurs under certain conditions in the transient filament stretching apparatus near the endplates as the plates are separated. Spiegelberg and McKinley [1] investigated this instability development in ...

The association between inflammatory back pain characteristics and MRI findings in the spine and sacroiliac joints

DEFF Research Database (Denmark)

Arnbak, Bodil; Jurik, Anne G; Jensen, Tue S

2018-01-01

OBJECTIVE: To investigate the association between MRI findings at the sacroiliac joints (SIJs) and vertebral endplates and pain characteristics assumed to be indicative of axial inflammation. METHODS: Patients aged 18-40 years with persistent low back pain referred to an outpatient spine clinic...

Design of a distributed radiator target for inertial fusion driven from two sides with heavy ion beams

International Nuclear Information System (INIS)

Tabak, M.; Callahan-Miller, D.

1997-01-01

We describe the status of a distributed radiator heavy ion target design. In integrated calculations this target ignited and produced 390-430 MJ of yieldwhen driven with 5.8-6.5 MJ of 3-4 GeV Pb ions. The target has cylindrical symmetry with disk endplates. The ions uniformly illuminate these endplates in a 5mm radius spot. We discuss the considerations which led to this design together with some previously unused design features: low density hohlraum walls in approximate pressure balance with internal low-Z fill materials, radiationsymmetry determined by the position of the radiator materials and particle ranges, and early time pressure symmetry possibly influenced by radiation shims. We discuss how this target scales to lower input energy or to lower beam power. Variant designs with more realistic beam focusing strategies are also discussed. We show the tradeoffs required for targets which accept higher particle energies

Vertebral physitis: a radiographic diagnosis to be separated from discospondylitis: a preliminary report

International Nuclear Information System (INIS)

Jimenez, M.M.; O'Callaghan, M.W.

1995-01-01

A retrospective study was initiated to investigate the incidence, radiographic appearance and progression of vertebral physitis, a condition the authors propose as a separate radiographic diagnosis from discospondylitis. From 30 dogs with an initial radiographic diagnosis of discospondylitis, six dogs (five less than two years old) had radiographic signs believed to represent vertebral physitis. Bone lysis initially confined to the caudal physeal zone of affected vertebrae and sparing the vertebral endplates characterized the vertebral physitis lesions. Subsequent collapse of the caudoventral vertebral body and reactive spondylosis arising only from the caudal vertebral margins followed as the lesions progressed. By contrast, discospondylitis lesions originated as symmetric lysis of the vertebral endplates with reactive sclerosis in both vertebral bodies, and subsequent symmetric spondylosis. As a result of the differing radiographic patterns demonstrated by the physitis and discospondylitis lesions the author's also propose an alternative pathogenesis from that which is generally accepted for discospondylitis

VARIABILITY OF MANUAL AND COMPUTERIZED METHODS FOR MEASURING CORONAL VERTEBRAL INCLINATION IN COMPUTED TOMOGRAPHY IMAGES

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Tomaž Vrtovec

2015-06-01

Full Text Available Objective measurement of coronal vertebral inclination (CVI is of significant importance for evaluating spinal deformities in the coronal plane. The purpose of this study is to systematically analyze and compare manual and computerized measurements of CVI in cross-sectional and volumetric computed tomography (CT images. Three observers independently measured CVI in 14 CT images of normal and 14 CT images of scoliotic vertebrae by using six manual and two computerized measurements. Manual measurements were obtained in coronal cross-sections by manually identifying the vertebral body corners, which served to measure CVI according to the superior and inferior tangents, left and right tangents, and mid-endplate and mid-wall lines. Computerized measurements were obtained in two dimensions (2D and in three dimensions (3D by manually initializing an automated method in vertebral centroids and then searching for the planes of maximal symmetry of vertebral anatomical structures. The mid-endplate lines were the most reproducible and reliable manual measurements (intra- and inter-observer variability of 0.7° and 1.2° standard deviation, SD, respectively. The computerized measurements in 3D were more reproducible and reliable (intra- and inter-observer variability of 0.5° and 0.7° SD, respectively, but were most consistent with the mid-wall lines (2.0° SD and 1.4° mean absolute difference. The manual CVI measurements based on mid-endplate lines and the computerized CVI measurements in 3D resulted in the lowest intra-observer and inter-observer variability, however, computerized CVI measurements reduce observer interaction.

Multimodal advanced imaging of the spine

International Nuclear Information System (INIS)

Tanenbaum, L.

2015-01-01

Full text: DWI is a powerful addition to the arsenal of MR imaging techniques for the detection of bone marrow tumor dissemination, improving sensitivity to involvement in a variety of tumor types. DWI increases confidence in monitoring treatment response and assisting in the differentiation of treatment related changes from tumor. DWI has also become an important component of whole-body MR oncology protocols. Distinguishing between benign and malignant etiologies of vertebral fracture with MRI is problematic, particularly if only one vertebra is affected. the value of DWI in discriminating between osteoporotic and metastatic vertebral fractures is controversial and by consensus insufficiently reliable. DWI is useful for differentiation of degenerative and infectious endplate abnormalities. Symptomatic degenerative vertebral endplate signal changes (Modic type 1) can be difficult to differentiate from acute spondylodiscitis using conventional MRI techniques. Several studies have shown that DWI adds value in differentiating degenerative and infectious endplate abnormalities. Recently a characteristic DWI finding of well-marginated, linear, typically paired regions of high signal at the interface of normal with abnormal marrow, referred to as a ‘claw’ sign, is been shown to be highly suggestive of degeneration and its absence in cases with Modic type I changes suggestive of diskitis/osteomyelitis. the value of excluding the possibility of infection can be seen in reduction in unnecessary, often invasive ancillary testing and reduced levels of patient concern. DWI may also yield insight into intervertebral disc degeneration. It has recently been shown in the lumbar spine that disc degeneration can influence ADC values with negative correlation between ADC and the degree of disc degeneration

Resting release of acetylcholine at the motor endplate

International Nuclear Information System (INIS)

Molenaar, P.C.; Polak, R.L.

1986-01-01

This paper reviews recent work on resting release of ACh in frog, rat and mouse skeletal muscle. Because of the effect of Ca 2+ on resting release it was of interest to know whether non-quantal release of ACh is increased under conditions of increased Ca 2+ influx, viz. during depolarization of the nerve terminals. It is shown that depolarization of the motor nerve terminals by K + ions led to an increase of both min.e.p.c. frequency and chemically detectable ACh release

Influência da procainamida sobre o bloqueio neuromuscular produzido pelo rocurônio e investigação sobre o mecanismo de ação da procainamida na junção neuromuscular Influencia de la procainamida sobre el bloqueo neuromuscular producido por el rocuronio e investigación sobre el mecanismo de acción de la procainamida en la junción neuromuscular Influence of procainamide on the neuromuscular blockade caused by rocuronium and investigation on the mechanism of action of procainamide on the neuromuscular junction

Directory of Open Access Journals (Sweden)

Thalita Duque Martins

2007-02-01

: It has already been proved that procainamide potentiates the neuromuscular blockade of d-tubocurarine; however, the mechanism of this potentiation is controversial. The aim of this study was to assess the influence of procainamide on the neuromuscular blockade produced by rocuronium and investigate the mechanisms of this interaction. METHODS: Fifteen rats (250 to 300 g were used in the preparation described by Bülbring. They were divided in three groups (n = 5 each: procainamide - 20 µg.mL-1 (Group I; rocuronium - 4 µg.mL-1 (Group II; and rocuronium - 4 µg.mL-1 and procainamide - 20 µg.mL-1 (Group III. The following parameters were evaluated: 1 amplitude of muscle contractions under indirect stimulation, before and after the administration of the drugs; 2 miniature end plate potentials (MEPPs; and 3 the efficacy of 4-aminopyridine in reverting the muscular blockade. The mechanism of the interaction was studied in Biventer cervicis (n = 5 and in the denervated rat diaphragm (n = 5, observing the influence of procainamide in the response to acetylcholine. RESULTS: Procainamide alone did not change the neuromuscular responses. Group III presented a 68.6% ± 7.1% blockade, which represented a statistically significant difference (p = 0.0067 when compared with Group II (10.4% ± 4.5%, which was reverted by 4-aminopiridine. Procainamide increased the frequency of the MEPP, followed by a blockade that was reverted by 4-aminopiridine. In Biventer cervicis, procainamide increased the contraction in response to acetylcholine, which was not observed in the denervated diaphragm. CONCLUSIONS: Procainamide potentiated the blockade caused by rocuronium. The changes observed with MEPP and Biventer cervicis identified pre-synaptic action. The antagonism of 4-aminopiridine on the blockade of the MEPP suggested receptor desensitization by procainamide.

Polymethylmethacrylate distribution is associated with recompression after vertebroplasty or kyphoplasty for osteoporotic vertebral compression fractures: A retrospective study

Science.gov (United States)

Yao, Qi; Zhang, Genai; Ding, Lixiang; Huang, Hui

2018-01-01

Background Osteoporotic vertebral compression fracture, always accompanied with pain and height loss of vertebral body, has a significant negative impact on life quality of patients. Vertebroplasty or kyphoplasty is minimal invasive techniques to reconstruct the vertebral height and prevent further collapse of the fractured vertebrae by injecting polymethylmethacrylate into vertebral body. However, recompression of polymethylmethacrylate augmented vertebrae with significant vertebral height loss and aggressive local kyphotic was observed frequently after VP or KP. The purpose of this study was to investigate the effect of polymethylmethacrylate distribution on recompression of the vertebral body after vertebroplasty or kyphoplasty surgery for osteoporotic vertebral compression fracture. Methods A total of 281 patients who were diagnosed with vertebral compression fracture (T5-L5) from June 2014 to June 2016 and underwent vertebroplasty or kyphoplasty by polymethylmethacrylate were retrospectively analyzed. The X-ray films at 1 day and 12 months after surgery were compared to evaluate the recompression of operated vertebral body. Patients were divided into those without recompression (non-recompression group) and those with recompression (recompression group). Polymethylmethacrylate distribution pattern, including location and relationship to endplates, was compared between the two groups by lateral X-ray film. Multivariate logistic regression analysis was performed to assess the potential risk factors associated with polymethylmethacrylate distribution for recompression. Results One hundred and six (37.7%) patients experienced recompression after surgery during the follow-up period. The polymethylmethacrylate distributed in the middle of vertebral body showed significant differences between two groups. In non-recompression group, the polymethylmethacrylate in the middle portion of vertebral body were closer to endplates than that in the recompression group (upper

On viscoelastic instability in polymeric filaments

DEFF Research Database (Denmark)

Rasmussen, Henrik Koblitz; Hassager, Ole

1999-01-01

The 3D Lagrangian Integral Method is used to simulate the effects of surface tension on the viscoelastic end-plate instability, occuring in the rapid extension of some polymeric filaments between parallel plates. It is shovn that the surface tension delays the onset of the instability. Furthermore...

Instability in the Peeling of a Polymeric Filament from a Rigid Surface

DEFF Research Database (Denmark)

Rasmussen, Henrik Koblitz; Hassager, Ole

2000-01-01

The 3D Lagrangian integral method is used to simulate the effects of the rheology on the viscoelastic end-plate instability, occuring in the rapid extension of some polymeric filaments between parallel plates.It is shown that strain hardening materials with a negative second normal stress differe...

Lagrangian Finite Element Method for 3D Time-Dependent Viscoelastic Flow Computations using Integral Models

DEFF Research Database (Denmark)

Rasmussen, Henrik Koblitz

2000-01-01

The 3D-LIM has as yet been used to simulate the following two three-dimensional problems. First, the method has been used to simulete for viscoelastic end-plate instability that occurs under certain conditions in the transient filament stretching apparatus for pressure sensitive adhesives (polyme...

Prototype for the ALEPH Time Projection Chamber

CERN Multimedia

1980-01-01

This is a prototype endplate piece constructed during R&D for the ALEPH Time Projection Chamber (TPC). ALEPH was one of 4 experiments at CERN's 27km Large Electron Positron collider (LEP) that ran from 1989 to 2000. ALEPH's TPC was a large-volume tracking chamber, 4.4 metres long and 3.6 metres in diameter - the largest TPC in existance at the time. This object is one of the endplates of a “Kind” sector, the smallest of the three types of sectors. The patterns etched into the copper form the cathode pads that measured particle track coordinates in the r-phi direction. It included a laser calibration system, a gating system to prevent space charge buildup, and a new radial pad geometry to improve resolution. the ALEPH TPC allowed for precise momentum measurements of the high-momentum particles from W and Z decays. The following institutes participated: CERN, Athens, Glasgow, Mainz, MPI Munich, INFN-Pisa, INFN-Trieste, Wisconsin.

CANDU fuel bundle deformation modelling with COMSOL multiphysics

International Nuclear Information System (INIS)

Bell, J.S.; Lewis, B.J.

2012-01-01

Highlights: ► The deformation behaviour of a CANDU fuel bundle was modelled. ► The model has been developed on a commercial finite-element platform. ► Pellet/sheath interaction and end-plate restraint effects were considered. ► The model was benchmarked against the BOW code and a variable-load experiment. - Abstract: A model to describe deformation behaviour of a CANDU 37-element bundle has been developed under the COMSOL Multiphysics finite-element platform. Beam elements were applied to the fuel elements (composed of fuel sheaths and pellets) and endplates in order to calculate the bowing behaviour of the fuel elements. This model is important to help assess bundle-deformation phenomena, which may lead to more restrictive coolant flow through the sub-channels of the horizontally oriented bundle. The bundle model was compared to the BOW code for the occurrence of a dry-out patch, and benchmarked against an out-reactor experiment with a variable load on an outer fuel element.

Nanoindentation of intervertebral disc tissues localised by SHG imaging

Czech Academy of Sciences Publication Activity Database

Šepitka, J.; Lukeš, J.; Staněk, L.; Filová, Eva; Burdíková, Zuzana; Řezníček, J.

2012-01-01

Roč. 15, Suppl.1 (2012), s. 335-336 ISSN 1025-5842 Institutional research plan: CEZ:AV0Z50390703; CEZ:AV0Z50390512; CEZ:AV0Z50110509 Keywords : nanoindentation * nanoDMA * endplate Subject RIV: BO - Biophysics; BO - Biophysics (FGU-C) Impact factor: 1.393, year: 2012

Lumbar lordosis and pars interarticularis fractures: a case-control study

International Nuclear Information System (INIS)

Bugg, William G.; Lewis, Mark; Juette, Arne; Cahir, John G.; Toms, Andoni P.

2012-01-01

The aim of this study is to examine the relationship between lumbar lordosis and pars interarticularis fractures. In this retrospective case-control study we compare the angle of lumbar lordosis and the angle of the S1 vertebral endplate (as a measure of pelvic tilt) in patients with bilateral L5 pars interarticularis fractures with age- and sex-matched control cases with normal MRI examinations of the lumbar spine. Twenty-nine cases of bilateral L5 pars interarticularis fractures with matched control-cases were identified on MRI (16 male, 13 female, age 9-63 years). The angle of lordosis was measured between the inferior L4 and superior S1 vertebral endplates on a standing lateral lumbar spine radiograph for both groups. The mean angle of lordosis about the L5 vertebra was 36.9 (SD = 6.5 ) in the pars interarticularis fracture group, and 30.1 (SD = 6.4 ) in the control group. The difference between the two groups was significant (mean difference 6.8 , Student's t test: P < 0.001). The mean angle of sacral tilt measured was 122.2 (SD = 10.16 ) for controls and 136.4 (SD = 10.86 ) for patients with pars defects. The difference in the means of 14.2 was statistically significantly different (P < 0.0001). Sacral tilt represented by a steeply angled superior endplate of S1 is associated with a significantly increased angle of lordosis, between L4 and S1, and pars fractures at L5. Steep angulation of the first sacral vertebral segment maybe the predisposing biomechanical factor that leads to pincer-like impingement of the pars interarticularis and then spondylolysis. (orig.)

Lumbar lordosis and pars interarticularis fractures: a case-control study

Energy Technology Data Exchange (ETDEWEB)

Bugg, William G; Lewis, Mark; Juette, Arne; Cahir, John G; Toms, Andoni P [Cotman Centre, Norwich Radiology Academy, Norwich, Norfolk (United Kingdom)

2012-07-15

The aim of this study is to examine the relationship between lumbar lordosis and pars interarticularis fractures. In this retrospective case-control study we compare the angle of lumbar lordosis and the angle of the S1 vertebral endplate (as a measure of pelvic tilt) in patients with bilateral L5 pars interarticularis fractures with age- and sex-matched control cases with normal MRI examinations of the lumbar spine. Twenty-nine cases of bilateral L5 pars interarticularis fractures with matched control-cases were identified on MRI (16 male, 13 female, age 9-63 years). The angle of lordosis was measured between the inferior L4 and superior S1 vertebral endplates on a standing lateral lumbar spine radiograph for both groups. The mean angle of lordosis about the L5 vertebra was 36.9 (SD = 6.5 ) in the pars interarticularis fracture group, and 30.1 (SD = 6.4 ) in the control group. The difference between the two groups was significant (mean difference 6.8 , Student's t test: P < 0.001). The mean angle of sacral tilt measured was 122.2 (SD = 10.16 ) for controls and 136.4 (SD = 10.86 ) for patients with pars defects. The difference in the means of 14.2 was statistically significantly different (P < 0.0001). Sacral tilt represented by a steeply angled superior endplate of S1 is associated with a significantly increased angle of lordosis, between L4 and S1, and pars fractures at L5. Steep angulation of the first sacral vertebral segment maybe the predisposing biomechanical factor that leads to pincer-like impingement of the pars interarticularis and then spondylolysis. (orig.)

Lumbar lordosis and pars interarticularis fractures: a case-control study

Energy Technology Data Exchange (ETDEWEB)

Bugg, William G.; Lewis, Mark; Juette, Arne; Cahir, John G.; Toms, Andoni P. [Cotman Centre, Norwich Radiology Academy, Norwich, Norfolk (United Kingdom)

2012-07-15

The aim of this study is to examine the relationship between lumbar lordosis and pars interarticularis fractures. In this retrospective case-control study we compare the angle of lumbar lordosis and the angle of the S1 vertebral endplate (as a measure of pelvic tilt) in patients with bilateral L5 pars interarticularis fractures with age- and sex-matched control cases with normal MRI examinations of the lumbar spine. Twenty-nine cases of bilateral L5 pars interarticularis fractures with matched control-cases were identified on MRI (16 male, 13 female, age 9-63 years). The angle of lordosis was measured between the inferior L4 and superior S1 vertebral endplates on a standing lateral lumbar spine radiograph for both groups. The mean angle of lordosis about the L5 vertebra was 36.9 (SD = 6.5 ) in the pars interarticularis fracture group, and 30.1 (SD = 6.4 ) in the control group. The difference between the two groups was significant (mean difference 6.8 , Student's t test: P < 0.001). The mean angle of sacral tilt measured was 122.2 (SD = 10.16 ) for controls and 136.4 (SD = 10.86 ) for patients with pars defects. The difference in the means of 14.2 was statistically significantly different (P < 0.0001). Sacral tilt represented by a steeply angled superior endplate of S1 is associated with a significantly increased angle of lordosis, between L4 and S1, and pars fractures at L5. Steep angulation of the first sacral vertebral segment maybe the predisposing biomechanical factor that leads to pincer-like impingement of the pars interarticularis and then spondylolysis. (orig.)

Adjacent level effects of bi level disc replacement, bi level fusion and disc replacement plus fusion in cervical spine--a finite element based study.

Science.gov (United States)

Faizan, Ahmad; Goel, Vijay K; Biyani, Ashok; Garfin, Steven R; Bono, Christopher M

2012-03-01

Studies delineating the adjacent level effect of single level disc replacement systems have been reported in literature. The aim of this study was to compare the adjacent level biomechanics of bi-level disc replacement, bi-level fusion and a construct having adjoining level disc replacement and fusion system. In total, biomechanics of four models- intact, bi level disc replacement, bi level fusion and fusion plus disc replacement at adjoining levels- was studied to gain insight into the effects of various instrumentation systems on cranial and caudal adjacent levels using finite element analysis (73.6N+varying moment). The bi-level fusion models are more than twice as stiff as compared to the intact model during flexion-extension, lateral bending and axial rotation. Bi-level disc replacement model required moments lower than intact model (1.5Nm). Fusion plus disc replacement model required moment 10-25% more than intact model, except in extension. Adjacent level motions, facet loads and endplate stresses increased substantially in the bi-level fusion model. On the other hand, adjacent level motions, facet loads and endplate stresses were similar to intact for the bi-level disc replacement model. For the fusion plus disc replacement model, adjacent level motions, facet loads and endplate stresses were closer to intact model rather than the bi-level fusion model, except in extension. Based on our finite element analysis, fusion plus disc replacement procedure has less severe biomechanical effects on adjacent levels when compared to bi-level fusion procedure. Bi-level disc replacement procedure did not have any adverse mechanical effects on adjacent levels. Copyright © 2011 Elsevier Ltd. All rights reserved.

Glutamate Receptor Aptamers and ALS

Science.gov (United States)

2008-01-01

2003b; 42(42):12358–66. uthman H, Magnusson G. High efficiency polyoma DNA transfection of chloroquine treated cells. Nucl Acids Res 1983;11(5):1295...by acetylcholine and its analogues at the frog muscle end-plate, J. Physiol. 369, 501-557. 20. Auerbach, A., and Sachs, F. (1984) Single-channel

The LDC detector concept

Indian Academy of Sciences (India)

foresees a TPC with around 200 points measured along a track, and read out by a system of micro-pattern gas detectors. These novel gas amplification devices promise to provide a stable, reliable readout system, which can be realized with comparatively little material in the endplate compared to a traditional wire readout.

Působení atropinu a diazepamu na savčí nervosvalové ploténce – model jejich ochranného působení při otravě bojovými a zemědělskými anticholinesterázami

Czech Academy of Sciences Publication Activity Database

Vyskočil, František

2006-01-01

Roč. 55, č. 3 (2006), s. 111-113 ISSN 1210-6313 R&D Projects: GA AV ČR(CZ) IAA5011411; GA ČR(CZ) GA305/02/1333; GA MŠk(CZ) LC554 Institutional research plan: CEZ:AV0Z50110509 Keywords : anticholinesterase * endplate * muscle membrane Subject RIV: ED - Physiology

MR imaging of degenerative disc disease

International Nuclear Information System (INIS)

Farshad-Amacker, Nadja A.; Farshad, Mazda; Winklehner, Anna; Andreisek, Gustav

2015-01-01

Highlights: • This systematic literature review summarizes the current knowledge on MR imaging in degenerative disc disease. • Different classification systems for segmental spine degeneration are summarized. • It outlines the diagnostic limitations of MR imaging. - Abstract: Magnet resonance imaging (MRI) is the most commonly used imaging modality for diagnosis of degenerative disc disease (DDD). Lack of precise observations and documentation of aspects within the complex entity of DDD might partially be the cause of poor correlation of radiographic findings to clinical symptoms. This literature review summarizes the current knowledge on MRI in DDD and outlines the diagnostic limitations. The review further sensitizes the reader toward awareness of potentially untended aspects of DDD and the interaction of DDD and endplate changes. A summary of the available classifications for DDD is provided

MR imaging of degenerative disc disease

Energy Technology Data Exchange (ETDEWEB)

Farshad-Amacker, Nadja A., E-mail: nadja.farshad@usz.ch [Institute of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich (Switzerland); Farshad, Mazda [Department of Orthopaedic Surgery, Balgrist University Hospital, Zurich (Switzerland); Winklehner, Anna; Andreisek, Gustav [Institute of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich (Switzerland)

2015-09-15

Highlights: • This systematic literature review summarizes the current knowledge on MR imaging in degenerative disc disease. • Different classification systems for segmental spine degeneration are summarized. • It outlines the diagnostic limitations of MR imaging. - Abstract: Magnet resonance imaging (MRI) is the most commonly used imaging modality for diagnosis of degenerative disc disease (DDD). Lack of precise observations and documentation of aspects within the complex entity of DDD might partially be the cause of poor correlation of radiographic findings to clinical symptoms. This literature review summarizes the current knowledge on MRI in DDD and outlines the diagnostic limitations. The review further sensitizes the reader toward awareness of potentially untended aspects of DDD and the interaction of DDD and endplate changes. A summary of the available classifications for DDD is provided.

Improvement of neuromuscular synaptic phenotypes without enhanced survival and motor function in severe spinal muscular atrophy mice selectively rescued in motor neurons.

Directory of Open Access Journals (Sweden)

Ximena Paez-Colasante

Full Text Available In the inherited childhood neuromuscular disease spinal muscular atrophy (SMA, lower motor neuron death and severe muscle weakness result from the reduction of the ubiquitously expressed protein survival of motor neuron (SMN. Although SMA mice recapitulate many features of the human disease, it has remained unclear if their short lifespan and motor weakness are primarily due to cell-autonomous defects in motor neurons. Using Hb9(Cre as a driver, we selectively raised SMN expression in motor neurons in conditional SMAΔ7 mice. Unlike a previous study that used choline acetyltransferase (ChAT(Cre+ as a driver on the same mice, and another report that used Hb9(Cre as a driver on a different line of conditional SMA mice, we found no improvement in survival, weight, motor behavior and presynaptic neurofilament accumulation. However, like in ChAT(Cre+ mice, we detected rescue of endplate size and mitigation of neuromuscular junction (NMJ denervation status. The rescue of endplate size occurred in the absence of an increase in myofiber size, suggesting endplate size is determined by the motor neuron in these animals. Real time-PCR showed that the expression of spinal cord SMN transcript was sharply reduced in Hb9(Cre+ SMA mice relative to ChAT(Cre+ SMA mice. This suggests that our lack of overall phenotypic improvement is most likely due to an unexpectedly poor recombination efficiency driven by Hb9(Cre . Nonetheless, the low levels of SMN were sufficient to rescue two NMJ structural parameters indicating that these motor neuron cell autonomous phenotypes are very sensitive to changes in motoneuronal SMN levels. Our results directly suggest that even those therapeutic interventions with very modest effects in raising SMN in motor neurons may provide mitigation of neuromuscular phenotypes in SMA patients.

Is the transport of a gadolinium-based contrast agent decreased in a degenerated or aged disc? A post contrast MRI study.

Directory of Open Access Journals (Sweden)

Marta Tibiletti

Full Text Available A post contrast magnetic resonance imaging study has been performed in a wide population of low back pain patients to investigate which radiological and phenotypic characteristics influence the penetration of the contrast agent in lumbar discs in vivo. 37 patients affected by different pathologies (disc herniation, spondylolisthesis, foraminal stenosis, central canal stenosis were enrolled in the study. The selected population included 26 male and 11 female subjects, with a mean age of 42.4 ± 9.3 years (range 18-60. Magnetic resonance images of the lumbar spine were obtained with a 1.5 T scanner (Avanto, Siemens, Erlangen, Germany with a phased-array back coil. A paramagnetic non-ionic contrast agent was injected with a dose of 0.4 ml/kg. T1-weighted magnetic resonance images were subsequently acquired at 5 time points, 5 and 10 minutes, 2, 4 and 6 hours after injection. Endplates presented clear enhancement already 5 minutes after injection, and showed an increase in the next 2 hours followed by a decrease. At 5 and 10 minutes, virtually no contrast medium was present inside the intervertebral disc; afterwards, enhancement significantly increased. Highly degenerated discs showed higher enhancement in comparison with low and medium degenerated discs. Discs classified as Pfirrmann 5 showed a statistically significant higher enhancement than Pfirrmann 1, 2 and 3 at all time points but the first one, possibly due to vascularization. Disc height collapse and Modic changes significantly increased enhancement. Presence of endplate defects did not show any significant influence on post contrast enhancement, but the lack of a clear classification of endplate defects as seen on magnetic resonance scans may be shadowing some effects. In conclusion, disc height, high level of degeneration and presence of Modic changes are factors which increase post contrast enhancement in the intervertebral disc. The effect of age could not be demonstrated.

Progressive pseudorheumatoid dysplasia

International Nuclear Information System (INIS)

Mampaey, S.; De Schepper, A.; Vanhoenacker, F.; Boven, K.; Hul, W. van

2000-01-01

A rare case of progressive pseudorheumatoid dysplasia (PPD) in a 9-year-old girl is presented. Clinically, chronic painless swollen joints, accompanied by progressive motion restriction and progressive walking difficulties, were found. Radiologically, there was enlargement of the epimetaphyseal portions of the large joints, metacarpal heads, and phalanges, and generalized platyspondyly with irregular delineation of the endplates of the vertebral bodies. The radioclinical features at the peripheral joints were originally misdiagnosed as juvenile rheumatoid arthritis (JRA), and the structural spinal abnormalities were neglected and interpreted as Scheuermann's disease. However, the absence of active inflammatory parameters argues against JRA, whereas the low age of onset of the irregularities at the vertebral endplates is an argument against the diagnosis of Scheuermann's disease. The combination of the dysplastic abnormalities of the spine, with platyspondyly and Scheuermann-like lesions at an unusually low age of onset, and radiological features mimicking JRA of the peripheral joints, is the clue to the diagnosis of this rare autosomal-recessive disease. This case is the first to document the MRI features of PPD of the spine. (orig.)

Radiation-induced changes of the developing nervous system of amphibians

International Nuclear Information System (INIS)

Schneider, M.

1986-01-01

The nervous system of amphibians (Xenopus laevis and Bufo) is of an outstanding sensitivity against irradiation in the early periods of its tissue induction and development. This is descriptively shown by various pathological disturbances. Irradiated series showed a protracted course of development. The brains obtains lower relative weights and diminished absolute lengths although the body weight remained nearly constant. The distribution of pigmentation in the brains of treated animals was changed. This indicated radiation-induced disturbances. Further, the significance of pigmentation pattern for a distinct evaluation of histological effects is also confirmed by a coincidence between the gross visible anomalies of the brain and the number of pigment-sites. Examples of malformation are given by aplasias, hypoplasias, hyperplasias up to cases of cyclopia. In the peripheral nervous system of Xenopus the neuromuscular junctions of the musculus interhyoideus were examined. The majority of neural endplates in the irradiated cases showed a loss of Schwann cells. As a consequence a diffusion of the transmitter acetylcholine in the endplate-region must be suggested. Accordingly, the morphological compensation reaction was seen in a thickening and sprouting. (orig.)

Glassy carbon supercapacitor: 100,000 cycles demonstrated

Energy Technology Data Exchange (ETDEWEB)

Baertsch, M; Braun, A; Schnyder, B; Koetz, R [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1999-08-01

A 5 V glassy carbon capacitor stack was built consisting of four bipolar and two end-plate electrodes. More than 100,000 charging/discharging cycles were applied to test the stability of the double-layer capacitor. Low and high frequency resistances were measured as a function of the number of cycles. (author) 2 figs., 1 ref.

Phenotype variations affect genetic association studies of degenerative disc disease: conclusions of analysis of genetic association of 58 single nucleotide polymorphisms with highly specific phenotypes for disc degeneration in 332 subjects.

Science.gov (United States)

Rajasekaran, S; Kanna, Rishi Mugesh; Senthil, Natesan; Raveendran, Muthuraja; Cheung, Kenneth M C; Chan, Danny; Subramaniam, Sakthikanal; Shetty, Ajoy Prasad

2013-10-01

Although the influence of genetics on the process of disc degeneration is well recognized, in recently published studies, there is a wide variation in the race and selection criteria for such study populations. More importantly, the radiographic features of disc degeneration that are selected to represent the disc degeneration phenotype are variable in these studies. The study presented here evaluates the association between single nucleotide polymorphisms (SNPs) of candidate genes and three distinct radiographic features that can be defined as the degenerative disc disease (DDD) phenotype. The study objectives were to examine the allelic diversity of 58 SNPs related to 35 candidate genes related to lumbar DDD, to evaluate the association in a hitherto unevaluated ethnic Indian population that represents more than one-sixth of the world population, and to analyze how genetic associations can vary in the same study subjects with the choice of phenotype. A cross-sectional, case-control study of an ethnic Indian population was carried out. Fifty-eight SNPs in 35 potential candidate genes were evaluated in 342 subjects and the associations were analyzed against three highly specific markers for DDD, namely disc degeneration by Pfirrmann grading, end-plate damage evaluated by total end-plate damage score, and annular tears evaluated by disc herniations and hyperintense zones. Genotyping of cases and controls was performed on a genome-wide SNP array to identify potential associated disease loci. The results from the genome-wide SNP array were then used to facilitate SNP selection and genotype validation was conducted using Sequenom-based genotyping. Eleven of the 58 SNPs provided evidence of association with one of the phenotypes. For annular tears, rs1042631 SNP of AGC1 and rs467691 SNP of ADAMTS5 were highly significantly associated (p<.01) and SNPs in NGFB, IL1B, IL18RAP, and MMP10 were also significantly associated (p<.05). The rs4076018 SNP of NGFB was highly

High bone turnover is associated with low bone mass and spinal fracture in postmenopausal women

DEFF Research Database (Denmark)

Ravn, Pernille; Rix, M; Andreassen, H

1997-01-01

-eight women had a lumbar spine bone mineral density (BMD) above 0.860 g/cm2, and 278 women had a BMD below 0.860 g/cm2. Spinal fracture was diagnosed from lateral spine X-ray studies and defined as at least 20% height reduction (wedge, compression, or endplate fracture) in at least one vertebra (T4-L4). Bone...

Fabrication and tests of prototype quadrupole magnets for the storage ring of the Advanced Photon Source

International Nuclear Information System (INIS)

Kim, S.H.; Thompson, K.M.; Black, E.L.; Jagger, J.M.

1991-01-01

Prototype quadrupole magnets for the APS storage ring have been fabricated and tested. Mechanical stability of the magnet poles and acceptable field quality have been achieved. Geometries of the pole-end bevels have been studied in order to simplify the design of the magnet end-plate. The field saturation at different segments of the magnet has been measured to evaluate the magnet efficiency

The Action of Botulinum Toxin at the Neuromuscular Junction

Science.gov (United States)

1980-12-22

fast - twitch " (gastrocnemius) and " slow - twitch " (soleus) muscles ... muscle fibers -"_re not significantly affected by the toxin. It is interesting to note that, although fast - twitch and slow - twitch mucles were...Duchen LW: An electron microscopic study of the changes induced by borulinum o::in in the motor end-plates of slow and fast skeletal muscle fibres of

Biomechanical evaluation of immediate stability with rectangular versus cylindrical interbody cages in stabilization of the lumbar spine

Directory of Open Access Journals (Sweden)

Webb John K

2002-10-01

Full Text Available Abstract Background Recent cadaver studies show stability against axial rotation with a cylindrical cage is marginally superior to a rectangular cage. The purpose of this biomechanical study in cadaver spine was to evaluate the stability of a new rectangular titanium cage design, which has teeth similar to the threads of cylindrical cages to engage the endplates. Methods Ten motion segments (five L2-3, five L4-5 were tested. From each cadaver spine, one motion segment was fixed with a pair of cylindrical cages (BAK, Sulzer Medica and the other with paired rectangular cages (Rotafix, Corin Spinal. Each specimen was tested in an unconstrained state, after cage introduction and after additional posterior translaminar screw fixation. The range of motion (ROM in flexion-extension, lateral bending, and rotation was tested in a materials testing machine, with +/- 5 Nm cyclical load over 10 sec per cycle; data from the third cycle was captured for analysis. Results ROM in all directions was significantly reduced (p Conclusions There was no significant difference in immediate stability in any direction between the threaded cylindrical cage and the new design of the rectangular cage with endplate teeth.

On the appearance of acetylcholine receptors in denervated rat diaphragm, and its dependence on nerve stump length

International Nuclear Information System (INIS)

Uchitel, O.; Robbins, N.

1978-01-01

Acetylcholine (ACh) sensitivity and extrajunctional receptor distribution of the rat diaphragm were closely monitored during the early period following denervation. Both contracture in response to 10 μg/ml of ACh and extrajunctional binding of [ 125 I]alpha-bungarotoxin ([ 125 I]α-BTX) were first detectable 30 h after cutting the phrenic nerve in the thorax. If the nerve were cut more proximally, leaving a 3.5 cm distal nerve stump, the same level of ACh contracture and [ 125 I]α-BTX binding did not appear until 40 h after operation. This 10-h delay was far longer than the 3-h delay in transmission failure reportedly dependent on stump length. The earliest detectable extrajunctional [ 125 I]α-BTX binding appeared throughout the entire muscle fiber, and was not localized to the endplate region as would be expected if degeneration in the nerve terminal induced new receptors. However, later significant increases in [ 125 I]α-BTX binding at the endplate region could have resulted from such degeneration. All these results are consistent with neurotrophic regulation of muscle ACh receptors, working via a mechanism involving axonal transport. (Auth.)

The maximum entropy production and maximum Shannon information entropy in enzyme kinetics

Science.gov (United States)

Dobovišek, Andrej; Markovič, Rene; Brumen, Milan; Fajmut, Aleš

2018-04-01

We demonstrate that the maximum entropy production principle (MEPP) serves as a physical selection principle for the description of the most probable non-equilibrium steady states in simple enzymatic reactions. A theoretical approach is developed, which enables maximization of the density of entropy production with respect to the enzyme rate constants for the enzyme reaction in a steady state. Mass and Gibbs free energy conservations are considered as optimization constraints. In such a way computed optimal enzyme rate constants in a steady state yield also the most uniform probability distribution of the enzyme states. This accounts for the maximal Shannon information entropy. By means of the stability analysis it is also demonstrated that maximal density of entropy production in that enzyme reaction requires flexible enzyme structure, which enables rapid transitions between different enzyme states. These results are supported by an example, in which density of entropy production and Shannon information entropy are numerically maximized for the enzyme Glucose Isomerase.

Autoradiographic visualization of extrajunctional acetylcholine receptors in whole human biceps brachii muscle

International Nuclear Information System (INIS)

Askmark, H.; Gillberg, P.-G.; Aquilonius, S.-M.

1985-01-01

The morphological distribution of acetylcholine receptors in the whole biceps brachii muscle from a patient with amyotrophic lateral sclerosis (ALS) and from a control patient was studied by in vitro autoradiography with 3 H-alpha-bungarotoxin alphaBtx). In ALS, 3 H-alpha-Btx binding occurred over the entire muscle, while in the control case the binding was restricted to the motor end-plate region. (author)

Glutamate regulation of non-quantal release of acetylcholine in the rat neuromuscular junction

Czech Academy of Sciences Publication Activity Database

Malomouzh, A. I.; Mukhtarov, M. R.; Nikolsky, E. E.; Vyskočil, František; Lieberman, E. M.; Urazaev, A. K.

2003-01-01

Roč. 85, č. 1 (2003), s. 206-213 ISSN 0022-3042 R&D Projects: GA AV ČR IAA7011902; GA ČR GA305/02/1333; GA ČR GA202/02/1213 Institutional research plan: CEZ:AV0Z5011922; CEZ:MSM 113100003 Keywords : muscle endplate * nitric oxide * N-methyl-D-aspartate receptor Subject RIV: CG - Electrochemistry Impact factor: 4.825, year: 2003

Schwann Cells in Neuromuscular Junction Formation and Maintenance.

Science.gov (United States)

Barik, Arnab; Li, Lei; Sathyamurthy, Anupama; Xiong, Wen-Cheng; Mei, Lin

2016-09-21

The neuromuscular junction (NMJ) is a tripartite synapse that is formed by motor nerve terminals, postjunctional muscle membranes, and terminal Schwann cells (TSCs) that cover the nerve-muscle contact. NMJ formation requires intimate communications among the three different components. Unlike nerve-muscle interaction, which has been well characterized, less is known about the role of SCs in NMJ formation and maintenance. We show that SCs in mice lead nerve terminals to prepatterned AChRs. Ablating SCs at E8.5 (i.e., prior nerve arrival at the clusters) had little effect on aneural AChR clusters at E13.5, suggesting that SCs may not be necessary for aneural clusters. SC ablation at E12.5, a time when phrenic nerves approach muscle fibers, resulted in smaller and fewer nerve-induced AChR clusters; however, SC ablation at E15.5 reduced AChR cluster size but had no effect on cluster density, suggesting that SCs are involved in AChR cluster maturation. Miniature endplate potential amplitude, but not frequency, was reduced when SCs were ablated at E15.5, suggesting that postsynaptic alterations may occur ahead of presynaptic deficits. Finally, ablation of SCs at P30, after NMJ maturation, led to NMJ fragmentation and neuromuscular transmission deficits. Miniature endplate potential amplitude was reduced 3 d after SC ablation, but both amplitude and frequency were reduced 6 d after. Together, these results indicate that SCs are not only required for NMJ formation, but also necessary for its maintenance; and postsynaptic function and structure appeared to be more sensitive to SC ablation. Neuromuscular junctions (NMJs) are critical for survival and daily functioning. Defects in NMJ formation during development or maintenance in adulthood result in debilitating neuromuscular disorders. The role of Schwann cells (SCs) in NMJ formation and maintenance was not well understood. We genetically ablated SCs during development and after NMJ formation to investigate the consequences

Anterior Overgrowth in Primary Curves, Compensatory Curves and Junctional Segments in Adolescent Idiopathic Scoliosis.

Science.gov (United States)

Schlösser, Tom P C; van Stralen, Marijn; Chu, Winnie C W; Lam, Tsz-Ping; Ng, Bobby K W; Vincken, Koen L; Cheng, Jack C Y; Castelein, René M

2016-01-01

Although much attention has been given to the global three-dimensional aspect of adolescent idiopathic scoliosis (AIS), the accurate three-dimensional morphology of the primary and compensatory curves, as well as the intervening junctional segments, in the scoliotic spine has not been described before. A unique series of 77 AIS patients with high-resolution CT scans of the spine, acquired for surgical planning purposes, were included and compared to 22 healthy controls. Non-idiopathic curves were excluded. Endplate segmentation and local longitudinal axis in endplate plane enabled semi-automatic geometric analysis of the complete three-dimensional morphology of the spine, taking inter-vertebral rotation, intra-vertebral torsion and coronal and sagittal tilt into account. Intraclass correlation coefficients for interobserver reliability were 0.98-1.00. Coronal deviation, axial rotation and the exact length discrepancies in the reconstructed sagittal plane, as defined per vertebra and disc, were analyzed for each primary and compensatory curve as well as for the junctional segments in-between. The anterior-posterior difference of spinal length, based on "true" anterior and posterior points on endplates, was +3.8% for thoracic and +9.4% for (thoraco)lumbar curves, while the junctional segments were almost straight. This differed significantly from control group thoracic kyphosis (-4.1%; P<0.001) and lumbar lordosis (+7.8%; P<0.001). For all primary as well as compensatory curves, we observed linear correlations between the coronal Cobb angle, axial rotation and the anterior-posterior length difference (r≥0.729 for thoracic curves; r≥0.485 for (thoraco)lumbar curves). Excess anterior length of the spine in AIS has been described as a generalized growth disturbance, causing relative anterior spinal overgrowth. This study is the first to demonstrate that this anterior overgrowth is not a generalized phenomenon. It is confined to the primary as well as the

MR imaging of lumbar spondylolysis: signal intensity change in the pars interarticularis and adjacent structures

Energy Technology Data Exchange (ETDEWEB)

Jang, Suk Whan; Lee, Ghi Jai; Shim, Jae Chan; Kim, Ho Kyun [Inje Univ. College of Medicine, Kimhae (Korea, Republic of)

2001-05-01

To assess changes in MR signal intensity in the pars interarticularis and adjacent structures in patients with lumbar spondylolysis. The MR images of 36 patients with lumbar spondylolysis, confirmed by plain radiographs, were retrospectively analyzed. Using a 1.0T unit, we evaluated the signal intensity of a total of 216 parts interarticulares and adjacent structures from L3 to L5, as seen on sagittal images, and differences between areas with and without spondylolysis. The signal intensity of T1-and T2-weighted images was graded 0(more hypointense than spinal body), 1(as isointense as spinal body), 2(more hyperintense than spinal body and more hypointense than epidural fat), or 3(as isointense as epidural fat). Signal intensity change in endplates and degree of spondylolisthesis were analyzed, and the relationship between these factors was determined. Spondylolysis was noted at L5 in 61 cases, at L4 in 22, and of L3 in no case. In three cases spondylolysis was unilateral, and in the remainder it was bilateral. The degree of signal intensity was the same on T1-and T2-weighted images, and no case was grade 0. Eighty-six of 133 areas without spondylolysis were grade 1, 43 were grade 2, and four were grade 3. In 42 of 47 cases, signal intensity change was localized at pedicles. Among 83 areas with spondylolysis,on the other hand, nine were grade 1, 48 were grade 2, and 26 were grade 3. Signal intensity change was most commonly observed at the pars interarticularis, pedicle, and lamina(50/74)({rho}<0.001). Signal intensity change at the pars interarticularis and adjacent structures was accompanied in most cases by degenerative endplate change(10/11) and spondylolisthesis(11/13)({rho}<0.001). In patients with spondylolysis, signal intensity was frequently higher at the pars interarticularis and adjacent structures, and is thought to have a close relationship with degenerative endplate change and spondylolisthesis. Increases in signal intensity at the pars

MR imaging of lumbar spondylolysis: signal intensity change in the pars interarticularis and adjacent structures

International Nuclear Information System (INIS)

Jang, Suk Whan; Lee, Ghi Jai; Shim, Jae Chan; Kim, Ho Kyun

2001-01-01

To assess changes in MR signal intensity in the pars interarticularis and adjacent structures in patients with lumbar spondylolysis. The MR images of 36 patients with lumbar spondylolysis, confirmed by plain radiographs, were retrospectively analyzed. Using a 1.0T unit, we evaluated the signal intensity of a total of 216 parts interarticulares and adjacent structures from L3 to L5, as seen on sagittal images, and differences between areas with and without spondylolysis. The signal intensity of T1-and T2-weighted images was graded 0(more hypointense than spinal body), 1(as isointense as spinal body), 2(more hyperintense than spinal body and more hypointense than epidural fat), or 3(as isointense as epidural fat). Signal intensity change in endplates and degree of spondylolisthesis were analyzed, and the relationship between these factors was determined. Spondylolysis was noted at L5 in 61 cases, at L4 in 22, and of L3 in no case. In three cases spondylolysis was unilateral, and in the remainder it was bilateral. The degree of signal intensity was the same on T1-and T2-weighted images, and no case was grade 0. Eighty-six of 133 areas without spondylolysis were grade 1, 43 were grade 2, and four were grade 3. In 42 of 47 cases, signal intensity change was localized at pedicles. Among 83 areas with spondylolysis,on the other hand, nine were grade 1, 48 were grade 2, and 26 were grade 3. Signal intensity change was most commonly observed at the pars interarticularis, pedicle, and lamina(50/74)(ρ<0.001). Signal intensity change at the pars interarticularis and adjacent structures was accompanied in most cases by degenerative endplate change(10/11) and spondylolisthesis(11/13)(ρ<0.001). In patients with spondylolysis, signal intensity was frequently higher at the pars interarticularis and adjacent structures, and is thought to have a close relationship with degenerative endplate change and spondylolisthesis. Increases in signal intensity at the pars interarticularis and

Discogentic lumbar pain: association with MRI and discography

International Nuclear Information System (INIS)

Chen Jianyu; Liu Qingyu; Liang Biling; Ye Ruixin; Zhong Jinglian

2008-01-01

Objective: To evaluate the correlation between MRI and X-Ray discography findings and pain response at provocative discography in patients with discogenic back pain. Methods: Two hundred and fifty-six lumbar intervertebral discs in 93 patients who underwent MRI and X-Ray discography were included in this study. MR images were retrospectively evaluated regarding disc degeneration, endplate abnormalities and high intensity zone. Disc degeneration was graded according to the modified criteria of Pearce, et al. Evaluation of disc morphology was performed with X-Ray discography by using the classification of Adams, et al. Endplates and adjacent bone marrow abnormalities were classified according to Modic,et al. During discography concordant pain was regarded as positive, whereas discordant pain and no pain were regarded as negative. The data were analyzed using the Chi-square test. Results: There were 116 discs with concordant pain and 140 discs with discordant pain or no pain. of 256 discs on discography , 17 discs were type I 17 (6.6%), type II were 25 (9.8%), type III were 91 (35.5%), type IV were 77(30.1%) and type V were 46(18.0%). On MR images, discs of grade I were 23 (9.0%), grade II were 34 (13.3%), grade III were 84 (32.8%), grade IV were 85 (33.2%) and grade V were 30(11.7% ). There was positive correlation between Pearce graded of MRI and classification of Adams of discography (r=0.62, χ 2 =160.87, P 2 =144.08, P 2 =137.11, P 2 = 51.93, P 2 =52.76, P<0.01). Conclusion: In patients with chronic low back pain, MR imaging may present moderate to severe disc degeneration, high intensity zone, endplates and adjacent bone marrow abnormalities. MR findings with concordant pain can raise the diagnostic possibility of discogenic lumbar pain. Typical discography findings, fissured or ruptured disc, with concordant pain are important diagnostic evidence for discogenic lumbar pain. (authors)

Long release latencies are increased by acetylcholine at frog endplate

Czech Academy of Sciences Publication Activity Database

Samigullin, D.; Bukharaeva, E. A.; Nikolsky, E.; Adámek, S.; Vyskočil, František

2003-01-01

Roč. 52, č. 4 (2003), s. 475-480 ISSN 0862-8408 R&D Projects: GA ČR GA305/02/1333; GA ČR GA202/02/1213 Grant - others:RFBR(RU) 02/04/48901 Institutional research plan: CEZ:AV0Z5011922; CEZ:MSM 113100003 Keywords : quantal release * acetylcholine * synaptic latency Subject RIV: ED - Physiology Impact factor: 0.939, year: 2003

Reinnervation of Paralyzed Muscle by Nerve-Muscle-Endplate Band Grafting

Science.gov (United States)

2017-10-01

period of low- frequency (20 Hz) continuous electrical stimulation of the proximal nerve stump at the time of operation40,41 and local administration...per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing...the vicinity. In addition, we used intraoperative 1-hour electrical stimulation (ES) and focal administration of exogenous neurotrophic factors

Reinnervation of Paralyzed Muscle by Nerve Muscle Endplate Band Grafting

Science.gov (United States)

2016-10-01

nerve branch supplying the NMEG was placed on bipolar stainless steel hook electrodes and stimulated. ES with supramaximal pulses (0.1 msec; 3V) was...Sprouting, synapse formation and repression. Neuroscience 1983;8(3):403– 416 18 Covault J, Cunningham JM, Sanes JR. Neurite outgrowth on cryostat

Reinnervation of Paralyzed Muscle by Nerve-Muscle-Endplate Band Grafting

Science.gov (United States)

2015-10-01

Antoniadis G, Braun V, Rath SA, Richter HP. Evaluation of iatrogenic lesions in 722 surgically treated cases of peripheral nerve trauma. J Neurosurg...achieved by end-to-end approximation: review of 2,181 nerve lesions . Microsurgery. 1993;14(4):244- 246. 18 25. McAllister RM, Gilbert SE, Calder JS...innervation through irreparable damage to its nerve . DNI has been used for selective reinnervation of paralyzed laryngeal and facial muscles [15,16] as well

Computational analysis of perturbations in the post-fusion Dengue virus envelope protein highlights known epitopes and conserved residues in the Zika virus [version 2; referees: 3 approved

Directory of Open Access Journals (Sweden)

Sandeep Chakraborty

2016-09-01

Full Text Available The dramatic transformation of the Zika virus (ZIKV from a relatively unknown virus to a pathogen generating global-wide panic has exposed the dearth of detailed knowledge about this virus. Decades of research in the related Dengue virus (DENV, finally culminating in a vaccine registered for use in endemic regions (CYD-TDV in three countries, provides key insights in developing strategies for tackling ZIKV, which has caused global panic to microcephaly and Guillain-Barre Syndrome. Dengue virus (DENV, a member of the family Flaviviridae, the causal agent of the self-limiting Dengue fever and the potentially fatal hemorrhagic fever/dengue shock syndrome, has been a scourge in tropical countries for many centuries. The recently solved structure of mature ZIKV (PDB ID:5IRE has provided key insights into the structure of the envelope (E and membrane (M proteins, the primary target of neutralizing antibodies. The previously established MEPP methodology compares two conformations of the same protein and identifies residues with significant spatial and electrostatic perturbations. In the current work, MEPP analyzed the pre-and post-fusion DENV type 2 envelope (E protein, and identified several known epitopes (His317, Tyr299, Glu26, Arg188, etc. (MEPPitope. These residues are overwhelmingly conserved in ZIKV and all DENV serotypes, and also enumerates residue pairs that undergo significant polarity reversal. Characterization of α-helices in E-proteins show that α1 is not conserved in the sequence space of ZIKV and DENV. Furthermore, perturbation of α1 in the post-fusion DENV structure includes a known epitope Asp215, a residue absent in the pre-fusion α1. A cationic β-sheet in the GAG-binding domain that is stereochemically equivalent in ZIKV and all DENV serotypes is also highlighted due to a residue pair (Arg286-Arg288 that has a significant electrostatic polarity reversal upon fusion. Finally, two highly conserved residues (Thr32 and Thr40, with

Improvements, verifications and validations of the BOW code

International Nuclear Information System (INIS)

Yu, S.D.; Tayal, M.; Singh, P.N.

1995-01-01

The BOW code calculates the lateral deflections of a fuel element consisting of sheath and pellets, due to temperature gradients, hydraulic drag and gravity. the fuel element is subjected to restraint from endplates, neighboring fuel elements and the pressure tube. Many new features have been added to the BOW code since its original release in 1985. This paper outlines the major improvements made to the code and verification/validation results. (author)

The prevalence of disc aging and back pain after fusion extending into the lower lumbar spine. A matched MR study twenty-five years after surgery for adolescent idiopathic scoliosis

Energy Technology Data Exchange (ETDEWEB)

Danielsson, A J; Nachemson, A L [Sahlgrenska Univ. Hospital, Goeteborg (Sweden). Dept. of Orthopaedics; Cederlund, C G; Ekholm, S [Sahlgrenska Univ. Hospital, Goeteborg (Sweden). Dept. of Diagnostic Radiology

2001-03-01

To determine the long-term outcome after fusion for adolescent idiopathic scoliosis in terms of degenerative disc findings diagnosed using MR imaging and to elucidate the clinical consequences. Material and methods: Thirty-two patients with adolescent idiopathic scoliosis, who had undergone spinal fusion using Harrington rods to the lower lumbar spine with one or two unfused discs below the fusion, were re-examined 25 years after the fusion. The re-examinations included validated questionnaires, clinical examination, full standing frontal and lateral radiographs and MR examination of the lower lumbar region. Curve size and degenerative findings on MR images were evaluated by two unbiased radiologists, blinded to the clinical findings. A matched control group of 32 persons without scoliosis was subjected to the same examinations. Results and conclusion: There were significantly more degenerative disc changes (p<0.0001), disc height reduction (p=0.0010) and end-plate changes (p<0.0001 for both upper and lower end-plates) in the lowest unfused disc in the patient group compared with the control group. The MR findings in the lowest unfused disc, but not the one above, in the patient group correlated to lumbar pain intensity as well as to the diminished lumbar lordosis.

The prevalence of disc aging and back pain after fusion extending into the lower lumbar spine. A matched MR study twenty-five years after surgery for adolescent idiopathic scoliosis

International Nuclear Information System (INIS)

Danielsson, A.J.; Nachemson, A.L.; Cederlund, C.G.; Ekholm, S.

2001-01-01

To determine the long-term outcome after fusion for adolescent idiopathic scoliosis in terms of degenerative disc findings diagnosed using MR imaging and to elucidate the clinical consequences. Material and methods: Thirty-two patients with adolescent idiopathic scoliosis, who had undergone spinal fusion using Harrington rods to the lower lumbar spine with one or two unfused discs below the fusion, were re-examined 25 years after the fusion. The re-examinations included validated questionnaires, clinical examination, full standing frontal and lateral radiographs and MR examination of the lower lumbar region. Curve size and degenerative findings on MR images were evaluated by two unbiased radiologists, blinded to the clinical findings. A matched control group of 32 persons without scoliosis was subjected to the same examinations. Results and conclusion: There were significantly more degenerative disc changes (p<0.0001), disc height reduction (p=0.0010) and end-plate changes (p<0.0001 for both upper and lower end-plates) in the lowest unfused disc in the patient group compared with the control group. The MR findings in the lowest unfused disc, but not the one above, in the patient group correlated to lumbar pain intensity as well as to the diminished lumbar lordosis

18F-PET imaging: frequency, distribution and appearance of benign lesions

International Nuclear Information System (INIS)

Schirrmeister, H.; Kotzerke, J.; Rentschler, M.; Traeger, H.; Fenchel, S.; Diederichs, C.G.; Reske, S.N.; Nuessle, K.

1998-01-01

Purpose: We evaluated the frequency, distribution and appearance of benign lesions in 18 F-PET scans. Methods: Between March 1996 and May 1997, 18 F-PET scans were performed in 59 patients in addition to conventional planar bone scintigraphy. Eleven patients were subjected to additional SPECT imaging. The main indication was searching for bone metastases (58 pat.). The diagnosis was confirmed radiologically. Results: With 18 F-PET in 39 patients (66,1%) 152 benign lesions, mostly located in the spine were detected. 99m Tc bone scans revealed 45 lesions in 10 patients. Osteoarthritis of the intervertebral articulations (69%) or of the acromioclavicular joint (15%) were the most common reasons for degenerative lesions detected with 18 F-PET. Osteophytes appeared as hot lesions located at two adjacent vertebral endplates. Osteoarthritis of the intervertebral articulations showed an enhanced tracer uptake at these localizations, whereas endplate fractures of the vertebral bodies appeared very typically; solitary fractures of the ribs could not be differentiated from metastases. Rare benign lesions were not studied. Conclusion: Most of the degenerative lesions (84%) detected with 18 F-PET had a very typical appearance and could be detected with the improved spatial resolution and advantages of a tomographic technique. 18 F-PET had an increased accuracy in detecting degenerative bone lesions. (orig.) [de

The LP-ESP(®) lumbar disc prosthesis with 6 degrees of freedom: development and 7 years of clinical experience.

Science.gov (United States)

Lazennec, Jean-Yves; Aaron, Alain; Brusson, Adrien; Rakover, Jean-Patrick; Rousseau, Marc-Antoine

2013-02-01

The viscoelastic lumbar disk prosthesis-elastic spine pad (LP-ESP(®)) is an innovative one-piece deformable but cohesive interbody spacer providing 6 full degrees of freedom about the 3 axes, including shock absorption. A 20-year research program has demonstrated that this concept provides mechanical properties very close to those of a natural disk. Improvements in technology have made it possible to solve the problem of the bond between the elastic component and the titanium endplates and to obtain an excellent biostability. The prosthesis geometry allows limited rotation and translation with resistance to motion (elastic return property) aimed at avoiding overload of the posterior facets. The rotation center can vary freely during motion. It thus differs substantially from current prostheses, which are 2- or 3-piece devices involving 1 or 2 bearing surfaces and providing 3 or 5 degrees of freedom. This design and the adhesion-molding technology differentiate the LP-ESP prosthesis from other mono-elastomeric prostheses, for which the constraints of shearing during rotations or movement are absorbed at the endplate interface. Seven years after the first implantation, we can document in a solid and detailed fashion the course of clinical outcomes and the radiological postural and kinematic behavior of this prosthesis.

Developmental plasticity of phrenic motoneuron and diaphragm properties with the inception of inspiratory drive transmission in utero.

Science.gov (United States)

Greer, John J; Martin-Caraballo, Miguel

2017-01-01

The review outlines data consistent with the hypothesis that inspiratory drive transmission that generates fetal breathing movements (FBMs) is essential for the developmental plasticity of phrenic motoneurons (PMNs) and diaphragm musculature prior to birth. A systematic examination during the perinatal period demonstrated a very marked transformation of PMN and diaphragm properties coinciding with the onset and strengthening of inspiratory drive and FBMs in utero. This included studies of age-dependent changes of: i) morphology, neuronal coupling, passive and electrophysiological properties of PMNs; ii) rhythmic inspiratory activity in vitro; iii) FBMs generated in vivo detected by ultrasonography; iv) contractile and end-plate potential properties of diaphragm musculature. We also propose how the hypothesis can be further evaluated with studies of perinatal hypoglossal motoneuron-tongue musculature and the use of Dbx1 null mice that provide an experimental model lacking descending inspiratory drive transmission in utero. Copyright © 2016 Elsevier Inc. All rights reserved.

İntervertebral disk patofizyolojisinde rol oynayan etmenler

OpenAIRE

Aktar Reyhanioğlu, Duygu

2014-01-01

Intervertebral disc locating between two vertebrae and maintaining support function and structures that remain vertebraes together. İt is the most important part of functional movement system and consisting of anulus fibrosus , nucleus pulposus, and vertebral endplate. İntervertebral disc degeneration is the loss of functionality of disc as a result of physiologic, chemical and mechanic pathology. As a result of functional unit damage occuring loss of function, spread all spinal column.In thi...

Imaging of degenerative lumbar intervertebral discs; linking anatomy, pathology and imaging.

Science.gov (United States)

Adams, Ashok; Roche, Oran; Mazumder, Asif; Davagnanam, Indran; Mankad, Kshitij

2014-09-01

Low back pain is a common medical condition that has significant implications for healthcare providers and the UK economy. Low back pain can be classified as 'specific' in which an underlying pathophysiological mechanism is identified (eg, herniated intervertebral disc). Advanced imaging should be performed in this situation and in those patients in whom systemic disease is strongly suspected. In the majority (approximately 90%), low back pain in 'non specific' and there is a weak correlation with imaging abnormalities. This is an area of ongoing research and remains controversial in terms of imaging approach and treatment (eg, theory of discogenic pain, interpretation and treatment of endplate changes). With regards Modic endplate changes, current research suggests that an infective component may be involved that may identify novel potential treatments in patients with chronic low back pain refractory to other treatment modalities. MRI is the imaging modality of choice for the assessment of degenerative changes in intervertebral discs. MRI has superior soft tissue contrast resolution when compared to other imaging modalities (eg, plain radiography, CT). An understanding of normal anatomy and MR appearances of intervertebral discs, particularly with regards to how these appearances change with advancing age, is required to aid image interpretation. Knowledge of the spectrum of degenerative processes that may occur in the intervertebral discs is required in order to identify and explain abnormal MRI appearances. As the communication of MRI findings may guide therapeutic decision making and surgical intervention, the terminology used by radiologists must be accurate and consistent. Therefore, description of degenerative disc changes in the current paper is based on the most up-to-date recommendations, the aim being to aid reporting by radiologists and interpretation of reports by referring clinicians. Published by the BMJ Publishing Group Limited. For permission to

Achondroplasia manifesting as enchondromatosis and ossification of the spinal ligaments: a case report

Directory of Open Access Journals (Sweden)

Al Kaissi Ali

2008-08-01

Full Text Available Abstract Introduction A girl presented with achondroplasia manifested as mild knee pain associated with stiffness of her back. A skeletal survey showed enchondroma-like metaphyseal dysplasia and ossification of the spinal ligaments. Magnetic resonance imaging of the spine further clarified the pathological composites. Case presentation A 7-year-old girl presented with the classical phenotypic features of achondroplasia. Radiographic documentation showed the co-existence of metaphyseal enchondromatosis and development of spinal bony ankylosis. Magnetic resonance imaging showed extensive ossification of the anterior and posterior spinal ligaments. Additional features revealed by magnetic resonance imaging included calcification of the peripheral vertebral bodies associated with anterior end-plate irregularities. Conclusion Enchondromas are metabolically active and may continue to grow and evolve throughout the patient's lifetime; thus, progressive calcification over a period of years is not unusual. Ossification of the spinal ligaments has a specific site of predilection and often occurs in combination with senile ankylosing vertebral hyperostosis. Nevertheless, ossification of the spinal ligaments has been encountered in children with syndromic malformation complex. It is a multifactorial disease in which complex genetic and environmental factors interact, potentially leading to chronic pressure on the spinal cord and nerve roots with subsequent development of myeloradiculopathy. Our patient presented with a combination of achondroplasia, enchondroma-like metaphyseal dysplasia and calcification of the spinal ligaments. We suggest that the development of heterotopic bone formation along the spinal ligaments had occurred through an abnormal ossified enchondral mechanism. We postulate that ossification of the spinal ligaments and metaphyseal enchondromatous changes are related to each other and represent impaired terminal differentiation of

A drift chamber system for a toroidal detector

International Nuclear Information System (INIS)

Barbosa, F.J.; Christo, S.; Cuevas, C.; Doolittle, G.; Doughty, D.C.; Hutton, C.; Joyce, D.; Mecking, B.A.; Mestayer, M.D.; Niczyporuk, B.; O'Meara, J.E.; Tilles, D.; Tuzel, W.; Yegneswaran, A.

1992-01-01

We present design details for drift chambers to be used in the CLAS detector at CEBAF. Novel features include nonparallel endplates fabricated from composite materials, a gas mixture which includes helium to reduce multiple scattering, low wire tension, and a hexagonal cell layout. Magnetic field strength in the active region ranges from 0 to 2 T, and wire length varies from 10 to 300 cm. We discuss specific construction details for the outer drift chambers. (orig.)

A drift chamber system for a toroidal detector

Energy Technology Data Exchange (ETDEWEB)

Barbosa, F.J.; Christo, S.; Cuevas, C.; Doolittle, G.; Doughty, D.C.; Hutton, C.; Joyce, D.; Mecking, B.A.; Mestayer, M.D.; Niczyporuk, B.; O' Meara, J.E.; Tilles, D.; Tuzel, W.; Yegneswaran, A. (CEBAF, Newport News, VA (United States))

1992-12-01

We present design details for drift chambers to be used in the CLAS detector at CEBAF. Novel features include nonparallel endplates fabricated from composite materials, a gas mixture which includes helium to reduce multiple scattering, low wire tension, and a hexagonal cell layout. Magnetic field strength in the active region ranges from 0 to 2 T, and wire length varies from 10 to 300 cm. We discuss specific construction details for the outer drift chambers. (orig.).

Do motor neurons contain functional prejunctional cholinoceptors?

International Nuclear Information System (INIS)

Bierkamper, C.G.; Aizenman, E.; Millington, W.R.

1986-01-01

This paper focuses on negative feedback by nicotinic cholinoceptors (nAChR) on motor nerve terminals. The authors attempt to prove the existence of the receptor, determine its pharmacologic characteristics, and demonstrate that it can alter ACh release. Acetylcholine release from the vascular perfused rat phrenic nerve-hemidiaphragm prepareation is assessed by three methods; measurement of force of contraction; direct assay of released ACh by radioenzymatic assay; and intracellular recording from the endplate region of the myofiber

Self-consistent EXAFS PDF Projection Method by Matched Correction of Fourier Filter Signal Distortion

International Nuclear Information System (INIS)

Lee, Jay Min; Yang, Dong-Seok

2007-01-01

Inverse problem solving computation was performed for solving PDF (pair distribution function) from simulated data EXAFS based on data FEFF. For a realistic comparison with experimental data, we chose a model of the first sub-shell Mn-0 pair showing the Jahn Teller distortion in crystalline LaMnO3. To restore the Fourier filtering signal distortion, involved in the first sub-shell information isolated from higher shell contents, relevant distortion matching function was computed initially from the proximity model, and iteratively from the prior-guess during consecutive regularization computation. Adaptive computation of EXAFS background correction is an issue of algorithm development, but our preliminary test was performed under the simulated background correction perfectly excluding the higher shell interference. In our numerical result, efficient convergence of iterative solution indicates a self-consistent tendency that a true PDF solution is convinced as a counterpart of genuine chi-data, provided that a background correction function is iteratively solved using an extended algorithm of MEPP (Matched EXAFS PDF Projection) under development

Radiographic measures of thoracic kyphosis in osteoporosis: Cobb and vertebral centroid angles

International Nuclear Information System (INIS)

Briggs, A.M.; Greig, A.M.; Wrigley, T.V.; Tully, E.A.; Adams, P.E.; Bennell, K.L.

2007-01-01

Several measures can quantify thoracic kyphosis from radiographs, yet their suitability for people with osteoporosis remains uncertain. The aim of this study was to examine the validity and reliability of the vertebral centroid and Cobb angles in people with osteoporosis. Lateral radiographs of the thoracic spine were captured in 31 elderly women with osteoporosis. Thoracic kyphosis was measured globally (T1-T12) and regionally (T4-T9) using Cobb and vertebral centroid angles. Multisegmental curvature was also measured by fitting polynomial functions to the thoracic curvature profile. Canonical and Pearson correlations were used to examine correspondence; agreement between measures was examined with linear regression. Moderate to high intra- and inter-rater reliability was achieved (SEM = 0.9-4.0 ). Concurrent validity of the simple measures was established against multisegmental curvature (r = 0.88-0.98). Strong association was observed between the Cobb and centroid angles globally (r = 0.84) and regionally (r 0.83). Correspondence between measures was moderate for the Cobb method (r 0.72), yet stronger for the centroid method (r = 0.80). The Cobb angle was 20% greater for regional measures due to the influence of endplate tilt. Regional Cobb and centroid angles are valid and reliable measures of thoracic kyphosis in people with osteoporosis. However, the Cobb angle is biased by endplate tilt, suggesting that the centroid angle is more appropriate for this population. (orig.)

Radiographic measures of thoracic kyphosis in osteoporosis: Cobb and vertebral centroid angles

Energy Technology Data Exchange (ETDEWEB)

Briggs, A.M.; Greig, A.M. [University of Melbourne, Centre for Health, Exercise and Sports Medicine, School of Physiotherapy, Victoria (Australia); University of Melbourne, Department of Medicine, Royal Melbourne Hospital, Victoria (Australia); Wrigley, T.V.; Tully, E.A.; Adams, P.E.; Bennell, K.L. [University of Melbourne, Centre for Health, Exercise and Sports Medicine, School of Physiotherapy, Victoria (Australia)

2007-08-15

Several measures can quantify thoracic kyphosis from radiographs, yet their suitability for people with osteoporosis remains uncertain. The aim of this study was to examine the validity and reliability of the vertebral centroid and Cobb angles in people with osteoporosis. Lateral radiographs of the thoracic spine were captured in 31 elderly women with osteoporosis. Thoracic kyphosis was measured globally (T1-T12) and regionally (T4-T9) using Cobb and vertebral centroid angles. Multisegmental curvature was also measured by fitting polynomial functions to the thoracic curvature profile. Canonical and Pearson correlations were used to examine correspondence; agreement between measures was examined with linear regression. Moderate to high intra- and inter-rater reliability was achieved (SEM = 0.9-4.0 ). Concurrent validity of the simple measures was established against multisegmental curvature (r = 0.88-0.98). Strong association was observed between the Cobb and centroid angles globally (r = 0.84) and regionally (r = 0.83). Correspondence between measures was moderate for the Cobb method (r = 0.72), yet stronger for the centroid method (r = 0.80). The Cobb angle was 20% greater for regional measures due to the influence of endplate tilt. Regional Cobb and centroid angles are valid and reliable measures of thoracic kyphosis in people with osteoporosis. However, the Cobb angle is biased by endplate tilt, suggesting that the centroid angle is more appropriate for this population. (orig.)

Experimental study of prequalified status of flush end plate connections

Directory of Open Access Journals (Sweden)

Sherif H.M. Hassanien

2016-04-01

Full Text Available Seismic design of steel structures is an essential part of the design process. Egyptian loading code development process continues in a high rate to catch up with emerging new concepts and standards. Steel design codes (ASD and LRFD are not developing in the same speed, which prevents the full utilization and application of loading code. The above reason leads to the need for evaluating flush end plate connections from prequalification point of view according to international standards. Due to the lack of sufficient experimental data on flush end-plate connections, an experimental program was conducted to investigate this topic. Six flush end-plate samples were designed according to the Egyptian code for steel construction (ECP205 ASD using different beam and column sections, bolt diameters and grades. A cyclic loading pattern defined by international standards was used in the testing process, and the performance was evaluated accordingly. Evaluation of M–Φ curves showed that in some cases flush end plate connections satisfy the strict requirements for prequalification. However, beam sections having limited depth fail to achieve prequalification criteria for the connections. Reduced web may be used to enhance the connection status and is investigated in one of the samples to evaluate its impact on connection performance and the failure mode. The proposed staggered hole configuration showed a promising performance.

Macrophage imaging by USPIO-enhanced MR for the differentiation of infectious osteomyelitis and aseptic vertebral inflammation

Energy Technology Data Exchange (ETDEWEB)

Bierry, Guillaume [University Hospital, Department of Radiology, Strasbourg (France); University Louis Pasteur, EA 3432, Strasbourg (France); Jehl, Francois [University Hospital of Strasbourg, Department of Bacteriology, Strasbourg (France); University Louis Pasteur, EA 3432, Strasbourg (France); Boehm, Nelly [University Louis Pasteur, Institute of Histology, Faculty of Medicine, Strasbourg (France); University Louis Pasteur, INSERM U666, Strasbourg (France); Robert, Philippe [Guerbet Research, Roissy (France); Dietemann, Jean-Louis; Kremer, Stephane [University Hospital, Department of Radiology, Strasbourg (France)

2009-07-15

The purpose of this study was to prospectively evaluate USPIO-enhanced MR imaging for the differentiation of vertebral infectious osteomyelitis and sterile inflammation. Vertebral osteomyelitis and sterile vertebral inflammation were induced in two groups of six rabbits each. MRI examinations were performed including unenhanced and gadolinium-enhanced fat-saturated SE T1w sequences. Once endplate enhancement was observed on the T1 gadolinium-enhanced MR sequence, a second MRI examination (SE T1w sequence) was performed 24 h after USPIO administration (45 {mu}mol Fe/kg). MR imaging was correlated with histopathological findings (macrophage immunostaining and Perls Prussian blue staining). On gadolinium-enhanced T1 sequences, a significant SNR increase in vertebral endplates was present in both groups without significant difference between the two groups (P = 0.26). On USPIO-enhanced T1 sequences, a significant SNR increase was only observed in the infection group (P = 0.03) with a significant difference in SNR between the infection and the sterile-inflammation groups (P = 0.002). Infected areas presented replacement of bone marrow by an intense macrophage infiltration, some being iron-loaded. Sterile inflammation showed a replacement of bone marrow by inflammatory tissue with only rare macrophages without any Perls blue staining. USPIO-enhanced MR imaging can distinguish infectious osteomyelitis from sterile vertebral inflammation due to different macrophage distributions in the two lesions. (orig.)

Frequent Benign, Nontraumatic, Noninflammatory Causes of Low Back Pain in Adolescents: MRI Findings

Directory of Open Access Journals (Sweden)

Aikaterini Solomou

2018-01-01

Full Text Available Introduction. Low back pain (LBP is common in children and adolescents. There are many factors that cause LBP, including structural disorders, degenerative changes, Scheuermann’s disease, fractures, inflammation, and tumors. Magnetic Resonance Imaging is the gold standard for diagnosing spinal abnormalities and is mandatory when neurological symptoms exist. The study focuses on common MRI findings in adolescents with persistent LBP, without history of acute trauma or evidence of either inflammatory or rheumatic disease. Materials and Methods. Eleven adolescents were submitted to thoracic and/or lumbar spine MRI due to persistent LBP. The protocol consisted of T1 WI, T2 WI, and T2 WI with FS, in the axial, sagittal, and coronal plane. Results. MRI revealed structural abnormalities (scoliosis and kyphosis in 4/11 (36.36%; disc abnormalities and endplate changes were found on 11/11 (100%. Typical Scheuermann’s disease was found in 3/11 (27.27%. Endplate changes were severe in Scheuermann’s patients and mild to moderate in the remaining 8/11 (72.72%. Kyphosis was in all cases secondary to Scheuermann’s disease. Disk bulges and hernias were found in 8/11 (72.72%, all located in the lumbar spine. Conclusion. In adolescents with LBP, structural spinal disorders, degenerative changes, and Scheuermann’s disease are commonly found on MRI; however, degenerative changes prevail.

Follow-up radiographs of the cervical spine after anterior fusion with titanium intervertebral disc

International Nuclear Information System (INIS)

Biederer, J.; Hutzelmann, A.; Heller, M.; Rama, B.

1999-01-01

Purpose: We examined the postoperative changes of the cervical spine after treatment of cervical nerve root compression with anterior cervical discectomy and fusion with a new titanium intervertebral disc. Patients and Methods: 37 patients were examined prior to, as well as 4 days, 6 weeks, and 7 months after surgery. Lateral view X-rays and functional imaging were used to evaluate posture and mobility of the cervical spine, the position of the implants, and the reactions of adjacent bone structures. Results: Implantation of the titanium disc led to post-operative distraction of the intervertebral space and slight lordosis. Within the first 6 months a slight loss of distraction and re-kyphosis due to impression of the implants into the vertebral end-plates were found in all patients. We noted partial infractions into the vertebral end-plates in 10/42 segments and slight mobility of the implants in 14/42 segments. Both groups of patients showed reactive spondylosis and local symptoms due to loosening of the implants. The pain subsided after onset of bone bridging and stable fixation of the loosened discs. Conclusions: The titanium intervertebral disc provides initial distraction of the fusioned segments with partial recurrence of kyphosis during the subsequent course. Loosening of the implants with local symptoms can be evaluated with follow-up X-rays and functional imaging. (orig.) [de

Modic Type 1 Changes: Detection Performance of Fat-Suppressed Fluid-Sensitive MRI Sequences.

Science.gov (United States)

Finkenstaedt, Tim; Del Grande, Filippo; Bolog, Nicolae; Ulrich, Nils; Tok, Sina; Kolokythas, Orpheus; Steurer, Johann; Andreisek, Gustav; Winklhofer, Sebastian

2018-02-01

 To assess the performance of fat-suppressed fluid-sensitive MRI sequences compared to T1-weighted (T1w) / T2w sequences for the detection of Modic 1 end-plate changes on lumbar spine MRI.  Sagittal T1w, T2w, and fat-suppressed fluid-sensitive MRI images of 100 consecutive patients (consequently 500 vertebral segments; 52 female, mean age 74 ± 7.4 years; 48 male, mean age 71 ± 6.3 years) were retrospectively evaluated. We recorded the presence (yes/no) and extension (i. e., Likert-scale of height, volume, and end-plate extension) of Modic I changes in T1w/T2w sequences and compared the results to fat-suppressed fluid-sensitive sequences (McNemar/Wilcoxon-signed-rank test).  Fat-suppressed fluid-sensitive sequences revealed significantly more Modic I changes compared to T1w/T2w sequences (156 vs. 93 segments, respectively; p definition of Modic I changes is not fully applicable anymore.. · Fat-suppressed fluid-sensitive MRI sequences revealed more/greater extent of Modic I changes.. · Finkenstaedt T, Del Grande F, Bolog N et al. Modic Type 1 Changes: Detection Performance of Fat-Suppressed Fluid-Sensitive MRI Sequences. Fortschr Röntgenstr 2018; 190: 152 - 160. © Georg Thieme Verlag KG Stuttgart · New York.

Slotted cage resonator for high-field magnetic resonance imaging of rodents

Energy Technology Data Exchange (ETDEWEB)

Marrufo, O; Vasquez, F; Solis, S E; Rodriguez, A O, E-mail: arog@xanum.uam.mx [Departamento de Ingenieria Electrica, Universidad Autonoma Metropolitana Iztapalapa, Mexico, DF 09340 (Mexico)

2011-04-20

A variation of the high-frequency cavity resonator coil was experimentally developed according to the theoretical frame proposed by Mansfield in 1990. Circular slots were used instead of cavities to form the coil endplates and it was called the slotted cage resonator coil. The theoretical principles were validated via a coil equivalent circuit and also experimentally with a coil prototype. The radio frequency magnetic field, B1, produced by several coil configurations was numerically simulated using the finite-element approach to investigate their performances. A transceiver coil, 8 cm long and 7.6 cm in diameter, and composed of 4 circular slots with a 15 mm diameter on both endplates, was built to operate at 300 MHz and quadrature driven. Experimental results obtained with the slotted cage resonator coil were presented and showed very good agreement with the theoretical expectations for the resonant frequency as a function of the coil dimensions and slots. A standard birdcage coil was also built for performance comparison purposes. Phantom images were then acquired to compute the signal-to-noise ratio of both coils showing an important improvement of the slotted cage coil over the birdcage coil. The whole-body images of the mouse were also obtained showing high-quality images. Volume resonator coils can be reliably built following the physical principles of the cavity resonator design for high-field magnetic resonance imaging applications of rodents.

Risk of vertebral insufficiency fractures in relation to compressive strength predicted by quantitative computed tomography

International Nuclear Information System (INIS)

Biggemann, M.; Hilweg, D.; Seidel, S.; Horst, M.; Brinckmann, P.

1991-01-01

Vertebral insufficiency fractures may result from excessive loading of normal and routine loading of osteoporotic spines. Fractures occur when the mechanical load exceeds the vertebral compressive strength, i.e., the maximum load a vertebra can tolerate. Vertebral compressive strength is determined by trabecular bone density and the size of end-plate area. Both parameters can be measured non-invasively by quanti-tative computed tomography (QCT). In 75 patients compressive strength (i.e., trabecular bone density and endplate area) of the vertebra L3 was determined using QCT. In addition, conventional radiographs of the spines were analysed for the prevalence of insufficiency fractures in each case. By relating fracture prevalence to strength, 3 fracture risk groups were found: a high-risk group with strength values of L3 5 kN and a fracture risk near 0 percent. Biomechanical measurements and model calculations indicate that spinal loads of 3 to 4 kN at L3/4 will be common in everyday activities. These data and the results described above suggest that spines with strength values of L3<3 kN are at an extremely high risk of insufficiency fractures in daily life. Advantages of fracture risk assessment by strength determination over risk estimation based on clinically used trabecular bone density measurements are discussed. (author). 18 refs.; 4 figs

Modelling the bending/bowing of composite beams such as nuclear fuel

International Nuclear Information System (INIS)

Tayal, M.

1989-01-01

Arrays of tubes are used in many engineered structures, such as in nuclear fuel bundles and in steam generators. The tubes can bend (bow) due to in-service temperatures and loads. Assessments of bowing of nuclear fuel elements can help demonstrate the integrity of fuel and of surrounding components, as a function of operating conditions such as channel power. The BOW code calculates the bending of composite beams such as fuel elements, due to gradients of temperature and due to hydraulic forces. The deflections and rotations are calculated in both lateral directions, for given conditions of temperatures. Wet and dry operation of the sheath can be simulated. BOW accounts for the following physical phenomena: circumferential and axial variations in the temperatures of the sheath and of the pellet; cracking of pellets; grip and slip between the pellets and the sheath; hydraulic drag; restraint from endplates, from neighbouring elements, and from the pressure-tube; gravity; concentric or eccentric welds between endcaps and endplate; neutron flux gradients; and variations of material properties with temperature. The code is based on fundamental principles of mechanics. The governing equations are solved numerically using the finite element method. Several comparisons with closed-form equations shoe that the solutions of BOW are accurate. BOW's predictions for initial in-reactor bow are also consistent with two post-irradiation measurements

The shape, stability and breakage of pendant liquid bridges

Science.gov (United States)

Padday, J. F.; Pétré, G.; Rusu, C. G.; Gamero, J.; Wozniak, G.

1997-12-01

Pendant liquid bridges are defined as pendant drops supporting a solid axisymmetric endplate at their lower end. The stability and shape properties of such bridges are defined in terms of the capillary properties of the system and of the mass and radius of the lower free-floating endplate. The forces acting in the pendant liquid bridge are defined exactly and expressed in dimensionless form. Numerical analysis has been used to derive the properties of a given bridge and it is shown that as the bridge grows by adding more liquid to the system a maximum volume is reached. At this maximum volume, the pendant bridge becomes unstable with the length of the bridge increasing spontaneously and irreversibly at constant volume. Finally the bridge breaks with the formation of a satellite drop or an extended thread. The bifurcation and breakage processes have been recorded using a high-speed video camera with a digital recording rate of up to 6000 frames per second. The details of the shape of the bridge bifurcation and breakage for many pendant bridge systems have been recorded and it is shown that satellite drop formation after rupture is not always viscosity dependent. Bifurcation and breakage in simulated low gravity demonstrated that breakage was very nearly symmetrical about a plane through the middle of the pendant bridge.

BOW. A computer code to predict lateral deflections of composite beams. A computer code to predict lateral deflections of composite beams

Energy Technology Data Exchange (ETDEWEB)

Tayal, M.

1987-08-15

Arrays of tubes are used in many engineered structures, such as in nuclear fuel bundles and in steam generators. The tubes can bend (bow) due to in-service temperatures and loads. Assessments of bowing of nuclear fuel elements can help demonstrate the integrity of fuel and of surrounding components, as a function of operating conditions such as channel power. The BOW code calculates the bending of composite beams such as fuel elements, due to gradients of temperature and due to hydraulic forces. The deflections and rotations are calculated in both lateral directions, for given conditions of temperatures. Wet and dry operation of the sheath can be simulated. Bow accounts for the following physical phenomena: circumferential and axial variations in the temperatures of the sheath and of the pellet; cracking of pellets; grip and slip between the pellets and the sheath; hydraulic drag; restraints from endplates, from neighbouring elements, and from the pressure-tube; gravity; concentric or eccentric welds between endcap and endplate; neutron flux gradients; and variations of material properties with temperature. The code is based on fundamental principles of mechanics. The governing equations are solved numerically using the finite element method. Several comparisons with closed-form equations show that the solutions of BOW are accurate. BOW`s predictions for initial in-reactor bow are also consistent with two post-irradiation measurements.

Unusual radiological features in Paget's disease of bone

International Nuclear Information System (INIS)

Moore, T.E.; Kathol, M.H.; El-Khoury, G.Y.; Walker, C.W.; Gendall, P.W.; Whitten, C.G.

1994-01-01

The radiological diagnosis of Paget's disease of bone is usually straightforward because most cases conform to well-established classic descriptions. Diagnosis becomes more difficult, however, when radiological appearances are not typical or other disease processes mask or alter the behavior of Paget's disease. Examples are presented to illustrate four categories of unusual radiological presentation of Paget's disease; (1) unusual disease progression, (2) massive post-immobilization lysis, (3) metastatic spread to pagetic bone, and (4) vertebral end-plate destruction that mimics infection. (orig.)

The Ekman-Hartmann layer in MHD Taylor-Couette flow

OpenAIRE

Szklarski, Jacek; Rüdiger, Günther

2007-01-01

We study magnetic effects induced by rigidly rotating plates enclosing a cylindrical MHD Taylor-Couette flow at the finite aspect ratio $H/D=10$. The fluid confined between the cylinders is assumed to be liquid metal characterized by small magnetic Prandtl number, the cylinders are perfectly conducting, an axial magnetic field is imposed $\\Ha \\approx 10$, the rotation rates correspond to $\\Rey$ of order $10^2-10^3$. We show that the end-plates introduce, besides the well known Ekman circulati...

Estimation of presynaptic calcium currents and endogenous calcium buffers at the frog neuromuscular junction with two different calcium fluorescent dyes.

Science.gov (United States)

Samigullin, Dmitry; Fatikhov, Nijaz; Khaziev, Eduard; Skorinkin, Andrey; Nikolsky, Eugeny; Bukharaeva, Ellya

2014-01-01

At the frog neuromuscular junction, under physiological conditions, the direct measurement of calcium currents and of the concentration of intracellular calcium buffers-which determine the kinetics of calcium concentration and neurotransmitter release from the nerve terminal-has hitherto been technically impossible. With the aim of quantifying both Ca(2+) currents and the intracellular calcium buffers, we measured fluorescence signals from nerve terminals loaded with the low-affinity calcium dye Magnesium Green or the high-affinity dye Oregon Green BAPTA-1, simultaneously with microelectrode recordings of nerve-action potentials and end-plate currents. The action-potential-induced fluorescence signals in the nerve terminals developed much more slowly than the postsynaptic response. To clarify the reasons for this observation and to define a spatiotemporal profile of intracellular calcium and of the concentration of mobile and fixed calcium buffers, mathematical modeling was employed. The best approximations of the experimental calcium transients for both calcium dyes were obtained when the calcium current had an amplitude of 1.6 ± 0.08 pA and a half-decay time of 1.2 ± 0.06 ms, and when the concentrations of mobile and fixed calcium buffers were 250 ± 13 μM and 8 ± 0.4 mM, respectively. High concentrations of endogenous buffers define the time course of calcium transients after an action potential in the axoplasm, and may modify synaptic plasticity.

Influence of the thermal boundary conditions on the flow and the isotope separation of a gas centrifuge

Energy Technology Data Exchange (ETDEWEB)

Novelli, P.

1981-11-01

The axisymmetric steady gas flow in a so called thermally driven ultracentrifuge at total reflux and its /sup 235/UF/sub 6/-/sup 238/UF/sub 6/- separating characteristics are treated numerically. The top and the bottom end-caps are thermally conducting and kept at temperatures generally depending on radius. Regarding the side-wall temperature conditions, three cases will be considered: (1) insulated side-wall; (2) side-wall at constant temperature; (3) linear temperature profile continuously joining the end-plate temperatures. 20 figures, 2 tables.

Effective potential for non-convex potentials

International Nuclear Information System (INIS)

Fujimoto, Y.; O'Raifeartaigh, L.; Parravicini, G.

1983-01-01

It is shown that the well-known relationship between the effective potential GAMMA and the vacuum graphs μ of scalar QFT follows directly from the translational invariance of the measure, and that it holds for all values of the fields phi if, and only if, the classical potential is convex. In the non-convex case μ appears to become complex for some values of phi, but it is shown that the complexity is only apparent and is due to the failure of the loop expansion. The effective potential actually remains real and well-defined for all phi, and reduces to μ in the neighbourhood of the classical minima. A number of examples are considered, notably potentials which are spontaneously broken. In particular the mechanism by which a spontaneous breakdown may be generated by radiative corrections is re-investigated and some new insights obtained. Finally, it is shown that the renormalization group equations for the parameters may be obtained by inspection from the effective potential, and among the examples considered are SU(n) fields and supermultiplets. In particular, it is shown that for supermultiplets the effective potential is not only real but positive. (orig.)

Protein kinase A cascade regulates quantal release dispersion at frog muscle endplate

Czech Academy of Sciences Publication Activity Database

Bukharaeva, E. A.; Samigullin, D.; Nikolsky, E.; Vyskočil, František

2002-01-01

Roč. 538, č. 3 (2002), s. 837-848 ISSN 0022-3751 R&D Projects: GA AV ČR IAA7011902 Grant - others:EU(XC) EU Nesting; RFBR(RU) 99-04-48286 Institutional research plan: CEZ:AV0Z5011922 Keywords : EPCs * latency dispersion * protein kinase A Subject RIV: ED - Physiology Impact factor: 4.650, year: 2002

Geometry of the Intervertebral Volume and Vertebral Endplates of the Human Spine

NARCIS (Netherlands)

van der Houwen, E. B.; Baron, P.; Veldhuizen, A. G.; Burgerhof, J. G. M.; van Ooijen, P. M. A.; Verkerke, G. J.

Replacement of a degenerated vertebral disc with an artificial intervertebral disc (AID) is currently possible, but poses problems, mainly in the force distribution through the vertebral column. Data on the intervertebral disc space geometry will provide a better fit of the prosthesis to the

Geometry of the Intervertebral Volume and Vertebral Endplates of the Human Spine

NARCIS (Netherlands)

van der Houwen, E.B.; Baron, P.; Veldhuizen, A.G.; Burgerhof, J.G.M.; van Ooijen, P.M.A.; Verkerke, Gijsbertus Jacob

2010-01-01

Replacement of a degenerated vertebral disc with an artificial intervertebral disc (AID) is currently possible, but poses problems, mainly in the force distribution through the vertebral column. Data on the intervertebral disc space geometry will provide a better fit of the prosthesis to the

MRI in patients with tuberculous spondylitis presenting as vertebra plana: A retrospective analysis and review of literature

International Nuclear Information System (INIS)

Sureka, J.; Samuel, S.; Keshava, S.N.; Venkatesh, K.; Sundararaj, G.D.

2013-01-01

Aim: To present the magnetic resonance imaging (MRI) findings of 10 patients with histopathologically proven tuberculous spondylitis (TS) presenting as vertebra plana (VP) on radiographs. Material and methods: Radiographs of 451 adult TS patients were reviewed. In this consecutive series, there were 11 patients who presented as VP. MRI of 10 of these patients was available for review. Results: VP-like collapse of a single vertebral body of the dorsal spine with preserved endplates and disc was seen in all cases. Epidural, pre- and para-vertebral soft tissue was found in all patients. Epidural soft tissue presenting on sagittal images as a convexity of the posterior longitudinal ligament was also found in all the signal of which was different from the involved vertebra on axial images. All patients showed posterior element involvement, which was characterized by preserved cortical outline without expansion. Conclusion: TS presenting with VP-like collapse of the bone is rare, accounting for 2.4% of the cases in the present series. MRI may show a collapsed vertebra with preserved endplates and disc. MRI findings that are suggestive of TS include: (1) signal intensity of the epidural soft-tissue mass on axial images, which is different from the vertebral body; (2) presence of a thin, T2-weighted hypointense capsule of the para-vertebral soft tissue; (3) posterior element involvement characterized by intact hypointense cortical outline without expansion; and (4) involvement of the costovertebral joint.

Numerical study on air turbines with enhanced techniques for OWC wave energy conversion

Science.gov (United States)

Cui, Ying; Hyun, Beom-Soo; Kim, Kilwon

2017-10-01

In recent years, the oscillating water column (OWC) wave energy converter, which can capture wave energy from the ocean, has been widely applied all over the world. As the essential part of the OWC system, the impulse and Wells turbines are capable of converting the low pressure pneumatic energy into the mechanical shaft power. As an enhanced technique, the design of endplate or ring attached to the blade tip is investigated numerically in this paper. 3D numerical models based on a CFD-software FLUENT 12.0 are established and validated by the corresponding experimental results from the reports of Setoguchi et al. (2004) and Takao et al. (2001). Then the flow fields and non-dimensional evaluating coefficients are calculated and analyzed under steady conditions. Results show that the efficiency of impulse turbine with ring can reach up to 0.49 when ϕ=1, which is 4% higher than that in the cases for the endplate-type and the original one. And the ring-type Wells turbine with fixed guide vanes shows the best performance with the maximal efficiency of 0.55, which is 22% higher than that of the original one. In addition, the quasi-steady analysis is used to calculate the mean efficiency and output-work of a wave cycle under sinusoidal flow condition. Taking all together, this study provides support for structural optimization of impulse turbine and Wells turbine in the future.

Micromechanics of the human vertebral body for forward flexion.

Science.gov (United States)

Yang, Haisheng; Nawathe, Shashank; Fields, Aaron J; Keaveny, Tony M

2012-08-09

To provide mechanistic insight into the etiology of osteoporotic wedge fractures, we investigated the spatial distribution of tissue at the highest risk of initial failure within the human vertebral body for both forward flexion and uniform compression loading conditions. Micro-CT-based linear elastic finite element analysis was used to virtually load 22 human T9 vertebral bodies in either 5° of forward flexion or uniform compression; we also ran analyses replacing the simulated compliant disc (E=8 MPa) with stiff polymethylmethacrylate (PMMA, E=2500 MPa). As expected, we found that, compared to uniform compression, forward flexion increased the overall endplate axial load on the anterior half of the vertebra and shifted the spatial distribution of high-risk tissue within the vertebra towards the anterior aspect of the vertebral body. However, despite that shift, the high-risk tissue remained primarily within the central regions of the trabecular bone and endplates, and forward flexion only slightly altered the ratio of cortical-to-trabecular load sharing at the mid-vertebral level (mean±SD for n=22: 41.3±7.4% compression; 44.1±8.2% forward flexion). When the compliant disc was replaced with PMMA, the anterior shift of high-risk tissue was much more severe. We conclude that, for a compliant disc, a moderate degree of forward flexion does not appreciably alter the spatial distribution of stress within the vertebral body. Copyright © 2012 Elsevier Ltd. All rights reserved.

A 6-DOF parallel bone-grinding robot for cervical disc replacement surgery.

Science.gov (United States)

Tian, Heqiang; Wang, Chenchen; Dang, Xiaoqing; Sun, Lining

2017-12-01

Artificial cervical disc replacement surgery has become an effective and main treatment method for cervical disease, which has become a more common and serious problem for people with sedentary work. To improve cervical disc replacement surgery significantly, a 6-DOF parallel bone-grinding robot is developed for cervical bone-grinding by image navigation and surgical plan. The bone-grinding robot including mechanical design and low level control is designed. The bone-grinding robot navigation is realized by optical positioning with spatial registration coordinate system defined. And a parametric robot bone-grinding plan and high level control have been developed for plane grinding for cervical top endplate and tail endplate grinding by a cylindrical grinding drill and spherical grinding for two articular surfaces of bones by a ball grinding drill. Finally, the surgical flow for a robot-assisted cervical disc replacement surgery procedure is present. The final experiments results verified the key technologies and performance of the robot-assisted surgery system concept excellently, which points out a promising clinical application with higher operability. Finally, study innovations, study limitations, and future works of this present study are discussed, and conclusions of this paper are also summarized further. This bone-grinding robot is still in the initial stage, and there are many problems to be solved from a clinical point of view. Moreover, the technique is promising and can give a good support for surgeons in future clinical work.

Pseudo potentials and model potentials in atomic collisions

International Nuclear Information System (INIS)

Reyes, O.; Jouin, H.; Fuentealba, P.

1988-01-01

In this work, it is discussed the main differences between the use of pseudo-potentials and model potentials in collision problems . It is shown the potential energy curves for distinct systems obtained with both kinds of potentials. (A.C.A.S.) [pt

Phase 2 and 3 wind tunnel tests of the J-97 powered, external augmentor V/STOL model. [conducted in Ames 40- by 80-foot wind tunnel

Science.gov (United States)

Garland, D. B.

1980-01-01

Modifications were made to the model to improve longitudinal acceleration capability during transition from hovering to wing borne flight. A rearward deflection of the fuselage augmentor thrust vector is shown to be beneficial in this regard. Other agmentor modifications were tested, notably the removal of both endplates, which improved acceleration performance at the higher transition speeds. The model tests again demonstrated minimal interference of the fuselage augmentor on aerodynamic lift. A flapped canard surface also shows negligible influence on the performance of the wing and of the fuselage augmentor.

Influência da nifedipina no bloqueio neuromuscular produzido pelo atracúrio e pelo cisatracúrio: estudo em preparações nervo frênico-diafragma de rato Influencia de la nifedipina en el bloqueo neuromuscular producido por atracurio y cisatracurio: estudio en preparación nervio frénico diafragma de ratón Influence of nifedipine on the neuromuscular block produced by atracurium and cistracurium: study in rat phrenic-diaphragmatic nerve preparation

Directory of Open Access Journals (Sweden)

Silmara Rodrigues de Sousa

2006-04-01

neuromuscular del atracurio y del cisatracurio, no cambió el potencial de membrana y produjo el aumento inicial en la frecuencia de los PPTM, seguida de bloqueo. CONCLUSIONES: La nifedipina, en la concentración empleada, potenció el bloqueo neuromuscular que el atracurio e cisatracurio produjeron. Estudios electrofisiológicos demostraron una acción presináptica y la ausencia de acción despolarizante sobre la fibra muscular.BACKGROUND AND OBJECTIVES: Calcium channel blockers may interact with neuromuscular blockers, increasing its effects. Research studies about this interaction display controversial results. In some studies these drugs produced neuromuscular blockage, or contracture, or no effect at all was proved over skeletal neuromuscular response. This study assessed the nifedipine effects over muscular responses and its possible interaction with neuromuscular blockers in rat diaphragm. METHODS: A number of 25 rats were used, weighing between 250 and 300 g and sacrificed under anesthesia with intraperitoneal pentobarbital (40 mg.kg-1. Preparation was mounted according to the technique described by Bulbring. Diaphragm was kept under tension, connected to an isometric transducer and subjected to an indirect stimulation of 0.1 Hz frequency. Diaphragm contractions were registered on a physiograph. In order to evaluate the effect of these drugs on neuromuscular transmission, they were added separately or associated to the preparation, on the following concentrations: nifedipine (4 µg.mL-1; atracurium (20 µg.mL-1; cistracurium (3 µg.mL-1. On phrenic-nerve preparation, the assessed items were: 1 the extent of diaphragm muscle response to indirect stimulation, before and 45 minutes after adding nifedipine and neuromuscular blockers separately and after the association of both drugs; 2 nifedipine effects on membrane potentials (MP and miniature end-plate potentials (MEPP. RESULTS: Employed separately, nifedipine did not alter the extent of muscular responses, but it did

Myogenic Potential of Whole Bone Marrow Mesenchymal Stem Cells In Vitro and In Vivo for Usage in Urinary Incontinence

Science.gov (United States)

Giammò, Alessandro; Boido, Marina; Rustichelli, Deborah; Mareschi, Katia; Errichiello, Edoardo; Parola, Maurizio; Ferrero, Ivana; Fagioli, Franca; Vercelli, Alessandro; Carone, Roberto

2012-01-01

Urinary incontinence, defined as the complaint of any involuntary loss of urine, is a pathological condition, which affects 30% females and 15% males over 60, often following a progressive decrease of rhabdosphincter cells due to increasing age or secondary to damage to the pelvic floor musculature, connective tissue and/or nerves. Recently, stem cell therapy has been proposed as a source for cell replacement and for trophic support to the sphincter. To develop new therapeutic strategies for urinary incontinence, we studied the interaction between mesenchymal stem cells (MSCs) and muscle cells in vitro; thereafter, aiming at a clinical usage, we analyzed the supporting role of MSCs for muscle cells in vitro and in in vivo xenotransplantation. MSCs can express markers of the myogenic cell lineages and give rise, under specific cell culture conditions, to myotube-like structures. Nevertheless, we failed to obtain mixed myotubes both in vitro and in vivo. For in vivo transplantation, we tested a new protocol to collect human MSCs from whole bone marrow, to get larger numbers of cells. MSCs, when transplanted into the pelvic muscles close to the external urethral sphincter, survived for a long time in absence of immunosuppression, and migrated into the muscle among fibers, and towards neuromuscular endplates. Moreover, they showed low levels of cycling cells, and did not infiltrate blood vessels. We never observed formation of cell masses suggestive of tumorigenesis. Those which remained close to the injection site showed an immature phenotype, whereas those in the muscle had more elongated morphologies. Therefore, MSCs are safe and can be easily transplanted without risk of side effects in the pelvic muscles. Further studies are needed to elucidate their integration into muscle fibers, and to promote their muscular transdifferentiation either before or after transplantation. PMID:23029081

Myogenic potential of whole bone marrow mesenchymal stem cells in vitro and in vivo for usage in urinary incontinence.

Directory of Open Access Journals (Sweden)

Monica Gunetti

Full Text Available Urinary incontinence, defined as the complaint of any involuntary loss of urine, is a pathological condition, which affects 30% females and 15% males over 60, often following a progressive decrease of rhabdosphincter cells due to increasing age or secondary to damage to the pelvic floor musculature, connective tissue and/or nerves. Recently, stem cell therapy has been proposed as a source for cell replacement and for trophic support to the sphincter. To develop new therapeutic strategies for urinary incontinence, we studied the interaction between mesenchymal stem cells (MSCs and muscle cells in vitro; thereafter, aiming at a clinical usage, we analyzed the supporting role of MSCs for muscle cells in vitro and in in vivo xenotransplantation. MSCs can express markers of the myogenic cell lineages and give rise, under specific cell culture conditions, to myotube-like structures. Nevertheless, we failed to obtain mixed myotubes both in vitro and in vivo. For in vivo transplantation, we tested a new protocol to collect human MSCs from whole bone marrow, to get larger numbers of cells. MSCs, when transplanted into the pelvic muscles close to the external urethral sphincter, survived for a long time in absence of immunosuppression, and migrated into the muscle among fibers, and towards neuromuscular endplates. Moreover, they showed low levels of cycling cells, and did not infiltrate blood vessels. We never observed formation of cell masses suggestive of tumorigenesis. Those which remained close to the injection site showed an immature phenotype, whereas those in the muscle had more elongated morphologies. Therefore, MSCs are safe and can be easily transplanted without risk of side effects in the pelvic muscles. Further studies are needed to elucidate their integration into muscle fibers, and to promote their muscular transdifferentiation either before or after transplantation.

Estimation of presynaptic calcium currents and endogenous calcium buffers at the frog neuromuscular junction with two different calcium fluorescent dyes

Directory of Open Access Journals (Sweden)

Dmitry eSamigullin

2015-01-01

Full Text Available At the frog neuromuscular junction, under physiological conditions, the direct measurement of calcium currents and of the concentration of intracellular calcium buffers—which determine the kinetics of calcium concentration and neurotransmitter release from the nerve terminal—has hitherto been technically impossible. With the aim of quantifying both Ca2+ currents and the intracellular calcium buffers, we measured fluorescence signals from nerve terminals loaded with the low-affinity calcium dye Magnesium Green or the high-affinity dye Oregon Green BAPTA-1, simultaneously with microelectrode recordings of nerve-action potentials and end-plate currents. The action-potential-induced fluorescence signals in the nerve terminals developed much more slowly than the postsynaptic response. To clarify the reasons for this observation and to define a spatiotemporal profile of intracellular calcium and of the concentration of mobile and fixed calcium buffers, mathematical modeling was employed. The best approximations of the experimental calcium transients for both calcium dyes were obtained when the calcium current had an amplitude of 1.6 ± 0.08 рА and a half-decay time of 1.2 ± 0.06 ms, and when the concentrations of mobile and fixed calcium buffers were 250 ± 13 µM and 8 ± 0.4 mM, respectively. High concentrations of endogenous buffers define the time course of calcium transients after an action potential in the axoplasm, and may modify synaptic plasticity.

Diagnosis of vertebral fractures in children: is a simplified algorithm-based qualitative technique reliable?

Energy Technology Data Exchange (ETDEWEB)

Adiotomre, E. [Sheffield Teaching Hospitals NHS Foundation Trust UK, Radiology Department, Sheffield (United Kingdom); Sheffield Children' s NHS Foundation Trust, Radiology Department, Sheffield (United Kingdom); Summers, L.; Digby, M. [University of Sheffield UK, Sheffield Medical School, Sheffield (United Kingdom); Allison, A.; Walters, S.J. [University of Sheffield UK, School of Health and Related Research, Sheffield (United Kingdom); Broadley, P.; Lang, I. [Sheffield Children' s NHS Foundation Trust, Radiology Department, Sheffield (United Kingdom); Offiah, A.C. [Sheffield Children' s NHS Foundation Trust, Radiology Department, Sheffield (United Kingdom); University of Sheffield UK, Academic Unit of Child Health, Sheffield (United Kingdom)

2016-05-15

Identification of osteoporotic vertebral fractures allows treatment opportunity reducing future risk. There is no agreed standardised method for diagnosing paediatric vertebral fractures. To evaluate the precision of a modified adult algorithm-based qualitative (ABQ) technique, applicable to children with primary or secondary osteoporosis. Three radiologists independently assessed lateral spine radiographs of 50 children with suspected reduction in bone mineral density using a modified ABQ scoring system and following simplification to include only clinically relevant parameters, a simplified ABQ score. A final consensus of all observers using simplified ABQ was performed as a reference standard for fracture characterisation. Kappa was calculated for interobserver agreement of the components of both scoring systems and intraobserver agreement of simplified ABQ based on a second read of 29 randomly selected images. Interobserver Kappa for modified ABQ scoring for fracture detection, severity and shape ranged from 0.34 to 0.49 Kappa for abnormal endplate and position assessment was 0.27 to 0.38. Inter- and intraobserver Kappa for simplified ABQ scoring for fracture detection and grade ranged from 0.37 to 0.46 and 0.45 to 0.56, respectively. Inter- and intraobserver Kappa for affected endplate ranged from 0.31 to 0.41 and 0.45 to 0.51, respectively. Subjectively, observers' felt simplified ABQ was easier and less time-consuming. Observer reliability of modified and simplified ABQ was similar, with slight to moderate agreement for fracture detection and grade/severity. Due to subjective preference for simplified ABQ, we suggest its use as a semi-objective measure of diagnosing paediatric vertebral fractures. (orig.)

Diagnosis of vertebral fractures in children: is a simplified algorithm-based qualitative technique reliable?

International Nuclear Information System (INIS)

Adiotomre, E.; Summers, L.; Digby, M.; Allison, A.; Walters, S.J.; Broadley, P.; Lang, I.; Offiah, A.C.

2016-01-01

Identification of osteoporotic vertebral fractures allows treatment opportunity reducing future risk. There is no agreed standardised method for diagnosing paediatric vertebral fractures. To evaluate the precision of a modified adult algorithm-based qualitative (ABQ) technique, applicable to children with primary or secondary osteoporosis. Three radiologists independently assessed lateral spine radiographs of 50 children with suspected reduction in bone mineral density using a modified ABQ scoring system and following simplification to include only clinically relevant parameters, a simplified ABQ score. A final consensus of all observers using simplified ABQ was performed as a reference standard for fracture characterisation. Kappa was calculated for interobserver agreement of the components of both scoring systems and intraobserver agreement of simplified ABQ based on a second read of 29 randomly selected images. Interobserver Kappa for modified ABQ scoring for fracture detection, severity and shape ranged from 0.34 to 0.49 Kappa for abnormal endplate and position assessment was 0.27 to 0.38. Inter- and intraobserver Kappa for simplified ABQ scoring for fracture detection and grade ranged from 0.37 to 0.46 and 0.45 to 0.56, respectively. Inter- and intraobserver Kappa for affected endplate ranged from 0.31 to 0.41 and 0.45 to 0.51, respectively. Subjectively, observers' felt simplified ABQ was easier and less time-consuming. Observer reliability of modified and simplified ABQ was similar, with slight to moderate agreement for fracture detection and grade/severity. Due to subjective preference for simplified ABQ, we suggest its use as a semi-objective measure of diagnosing paediatric vertebral fractures. (orig.)

A Radiographic Measurement of the Anterior Epidural Space at L4-5 Disc Level.

Science.gov (United States)

Xu, Rui-Sheng; Wu, Jie-Shi; Lu, Hai-Dan; Zhu, Hao-Gang; Li, Xia; Dong, Jian; Yuan, Feng-Lai

2017-05-01

To observe the morphology character of the anterior epidural space at the L 4-5 disc level and to provide an anatomical basis for safely and accurately performing a percutaneous endoscopic lumbar discectomy (PELD). Fifty-five cases with L 5 S 1 lumbar disc herniation were included in this study, and cases with L 4-5 disease were excluded. When the puncture needle reached the epidural space at the L 5 S 1 level, iohexol was injected at the pressure of 50 cm H 2 O during the PELD, then C-Arm fluoroscopy was used to obtain standard lumbar frontal and lateral images. The widths of epidural space at the level of the L 4 lower endplate, the L 5 upper endplate, as well as the middle point of the L 4-5 disc were measured from the lumbar lateral X-ray film. Epidural space at the L 4-5 disc plane performs like a trapezium chart with a short side at the head end and a long side at the tail end in the lumbar lateral X-ray radiograph, while the average widths of epidural space were 10.2 ± 2.5, 12.3 ± 2.3, and 13.8 ± 2.6 mm at the upper, middle, and lower level of the L 4-5 disc. Understanding the morphological characteristics of epidural space will contribute to improving the safety of the tranforaminal percutaneous endoscopy technique. © 2017 Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.

Blocking p75 (NTR) receptors alters polyinnervationz of neuromuscular synapses during development.

Science.gov (United States)

Garcia, Neus; Tomàs, Marta; Santafe, Manel M; Lanuza, Maria A; Besalduch, Nuria; Tomàs, Josep

2011-09-01

High-resolution immunohistochemistry shows that the receptor protein p75(NTR) is present in the nerve terminal, muscle cell, and glial Schwann cell at the neuromuscular junction (NMJ) of postnatal rats (P4-P6) during the synapse elimination period. Blocking the receptor with the antibody anti-p75-192-IgG (1-5 μg/ml, 1 hr) results in reduced endplate potentials (EPPs) in mono- and polyinnervated synapses ex vivo, but the mean number of functional inputs per NMJ does not change for as long as 3 hr. Incubation with exogenous brain-derived neurotrophic factor (BDNF) for 1 hr (50 nM) resulted in a significant increase in the size of the EPPs in all nerve terminals, and preincubation with anti-p75-192-IgG prevented this potentiation. Long exposure (24 hr) in vivo of the NMJs to the antibody anti-p75-192-IgG (1-2 μg/ml) results in a delay of postnatal synapse elimination and even some regrowth of previously withdrawn axons, but also in some acceleration of the morphologic maturation of the postsynaptic nicotinic acetylcholine receptor (nAChR) clusters. The results indicate that p75(NTR) is involved in both ACh release and axonal retraction during postnatal axonal competition and synapse elimination. Copyright © 2011 Wiley-Liss, Inc.

PV potential and potential PV rent in European regions

DEFF Research Database (Denmark)

Hansen, Anders Chr.; Thorn, Paul

2013-01-01

The paper provides a GIS based model for assessing the potentials of photovoltaic electricity in Europe by NUTS 2 regions. The location specific energy potential per PV-­‐panel area is estimated based on observations of solar irradiation, conversion efficiency, levelised costs and the social value...... of PV-­‐electricity. Combined with the potential density of PV-­‐panel area based on land cover and environental restrictions, the PV energy potential and the potential PV ressource rent is calculated. These calculations enbable the model to estimate the regional patterns at NUTS 2 level...

Mechanical performance of full-scale prototype quadrupole magnets for the SSC

International Nuclear Information System (INIS)

Cortella, J.M.; Wandesforde, A.; Devred, A.

1992-08-01

Six 5-m-long prototype quadrupole magnets have been built and cold-tested at Lawrence Berkeley Laboratory for the Superconducting Super Collider. Each of the magnets contained instrumentation to monitor the mechanical performance of the magnets during assembly and cold-testing. In addition, the instrumentation was used along with physical measurements as aids during magnet assembly. Quantities measured include coil pressures during assembly, cooldown, and magnet energization; axial thermal contraction of the magnets during cooldown; and axial force transmitted to the magnet end-plates. For the most part, mechanical measurements have proven repeatable and agree well with analysis

CANFLEX fuel bundle cross-flow endurance test 2 (Test report)

Energy Technology Data Exchange (ETDEWEB)

Hong, Sung Deok; Chung, C. H.; Chang, S. K.; Kim, B. D. [Korea Atomic Energy Research Institute, Taejeon (Korea)

2000-02-01

This report describes cross-flow endurance test 2 that was conducted at the CANDU-Hot Test Loop. The test was completed on March 30, 1999 using a new CANFLEX bundle, built by KAERI. It was carried out for a total of 22 hours. After an initial period of ten hours, the test was stopped at the intervals of four hours for bundle inspection and inter-element gap measurement[7]. The test bundle end-plate to end-cap welds were inspected carefully for failure or crack propagation using liquid penetrant examination especially at the heat-affected zones. 12 refs., 4 figs., 10 tabs. (Author)

Construction of the Cleo III drift chamber

International Nuclear Information System (INIS)

Csorna, S.; Marka, S.; Dickson, M.; Dombrowski, S. von; Peterson, D.; Thies, P.; Glenn, S.; Thorndike, E.H.; Kravchenko, I.

1998-01-01

The CLEO III group is constructing a new chamber to be installed as part of the staged luminosity upgrade program at the Cornell electron storage ring and compatible with the interaction region optics. Although having less radial extent than the current CLEO II tracking system, CLEO III will have equivalent momentum resolution because of material reduction in the drift chamber inner skin and gas. The thin inner skin requires special attention to the end-plate motion due to wire creep. During stringing, use of a robot will fully automate the wire handling on the upper end. (author)

Pseudarthrosis after lumbar spinal fusion: the role of {sup 18}F-fluoride PET/CT

Energy Technology Data Exchange (ETDEWEB)

Peters, Marloes; Willems, Paul; Jutten, Liesbeth; Arts, Chris; Rhijn, Lodewijk van [Maastricht University Medical Center, Department of Orthopedic Surgery, Postbox 5800, Maastricht (Netherlands); Weijers, Rene; Wierts, Roel; Urbach, Christian; Brans, Boudewijn [Maastricht University Medical Center, Radiology /Nuclear Medicine, Maastricht (Netherlands)

2015-11-15

Painful pseudarthrosis is one of the most important indications for (revision) surgery after spinal fusion procedures. If pseudarthrosis is the source of recurrent pain it may require revision surgery. It is therefore of great clinical importance to ascertain if it is the source of such pain. The correlation between findings on conventional imaging (plain radiography and CT) and clinical well-being has been shown to be moderate. The goal of this study was to determine the possible role of {sup 18}F-fluoride PET in patients after lumbar spinal interbody fusion by investigating the relationship between PET/CT findings and clinical function and pain. A cohort of 36 patients was retrospectively included in the study after {sup 18}F-fluoride PET/CT for either persistent or recurrent low back pain (18 patients) or during routine postoperative investigation (18 patients) between 9 and 76 months and 11 and 14 months after posterior lumbar interbody fusion, respectively. Sixty minutes after intravenous injection of 156 - 263 MBq (mean 199 MBq, median 196 MBq) {sup 18}F-fluoride, PET and CT images were acquired using an integrated PET/CT scanner, followed by a diagnostic CT scan. Two observers independently scored the images. The number of bony bridges between vertebrae was scored on the CT images to quantify interbody fusion (0, 1 or 2). Vertebral endplate and intervertebral disc space uptake were evaluated visually as well as semiquantitatively following {sup 18}F-fluoride PET. Findings on PET and CT were correlated with clinical wellbeing as measured by validated questionnaires concerning general daily functioning (Oswestry Disability Index), pain (visual analogue scale) and general health status (EuroQol). Patients were divided into three categories based on these questionnaire scores. No correlation was found between symptom severity and fusion status. However, {sup 18}F-fluoride activity in the vertebral endplates was significantly higher in patients in the lowest

Pseudarthrosis after lumbar spinal fusion: the role of 18F-fluoride PET/CT

International Nuclear Information System (INIS)

Peters, Marloes; Willems, Paul; Jutten, Liesbeth; Arts, Chris; Rhijn, Lodewijk van; Weijers, Rene; Wierts, Roel; Urbach, Christian; Brans, Boudewijn

2015-01-01

Painful pseudarthrosis is one of the most important indications for (revision) surgery after spinal fusion procedures. If pseudarthrosis is the source of recurrent pain it may require revision surgery. It is therefore of great clinical importance to ascertain if it is the source of such pain. The correlation between findings on conventional imaging (plain radiography and CT) and clinical well-being has been shown to be moderate. The goal of this study was to determine the possible role of 18 F-fluoride PET in patients after lumbar spinal interbody fusion by investigating the relationship between PET/CT findings and clinical function and pain. A cohort of 36 patients was retrospectively included in the study after 18 F-fluoride PET/CT for either persistent or recurrent low back pain (18 patients) or during routine postoperative investigation (18 patients) between 9 and 76 months and 11 and 14 months after posterior lumbar interbody fusion, respectively. Sixty minutes after intravenous injection of 156 - 263 MBq (mean 199 MBq, median 196 MBq) 18 F-fluoride, PET and CT images were acquired using an integrated PET/CT scanner, followed by a diagnostic CT scan. Two observers independently scored the images. The number of bony bridges between vertebrae was scored on the CT images to quantify interbody fusion (0, 1 or 2). Vertebral endplate and intervertebral disc space uptake were evaluated visually as well as semiquantitatively following 18 F-fluoride PET. Findings on PET and CT were correlated with clinical wellbeing as measured by validated questionnaires concerning general daily functioning (Oswestry Disability Index), pain (visual analogue scale) and general health status (EuroQol). Patients were divided into three categories based on these questionnaire scores. No correlation was found between symptom severity and fusion status. However, 18 F-fluoride activity in the vertebral endplates was significantly higher in patients in the lowest Oswestry Disability Index

The Effect of Electrical Stimulation in Improving Muscle Tone (Clinical)

Science.gov (United States)

Azman, M. F.; Azman, A. W.

2017-11-01

Electrical stimulation (ES) and also known as neuromuscular electrical stimulation (NMES) and transcutaneous electrical stimulation (TES) involves the use of electrical current to stimulate the nerves or nerve endings that innervate muscle beneath the skin. Electrical stimulation may be applied superficially on the skin (transcutaneously) or directly into a muscle or muscles (intramuscularly) for the primary purpose of enhancing muscle function. The basic theoretical premise is that if the peripheral nerve can be stimulated, the resulting excitation impulse will be transmitted along the nerve to the motor endplates in the muscle, producing a muscle contraction. In this work, the effect of mere electrical stimulation to the muscle bulk and strength are tested. This paper explains how electrical stimulation can affect the muscle bulk, muscle size, muscle tone, muscle atrophy and muscle strength. The experiment and data collection are performed on 5 subjects and the results obtained are analyzed. This research aims to understand the full potential of electrical stimulation and identifying its possible benefits or disadvantages to the muscle properties. The results indicated that electrical stimulation alone able to improve muscle properties but with certain limits and precautions which might be useful in rehabilitation programme.

Nested Potential Games

OpenAIRE

Hiroshi Uno

2007-01-01

This paper proposes a new class of potential games, the nested potential games, which generalize the potential games defined in Monderer and Shapley (1996), as well as the pseudo-potential games defined in Dubey et al. (2006). We show that each maximizer of a nested potential is a Nash equilibrium.

Potential Theory

CERN Document Server

Lukeš, Jaroslav; Netuka, Ivan; Veselý, Jiří

1988-01-01

Within the tradition of meetings devoted to potential theory, a conference on potential theory took place in Prague on 19-24, July 1987. The Conference was organized by the Faculty of Mathematics and Physics, Charles University, with the collaboration of the Institute of Mathematics, Czechoslovak Academy of Sciences, the Department of Mathematics, Czech University of Technology, the Union of Czechoslovak Mathematicians and Physicists, the Czechoslovak Scientific and Technical Society, and supported by IMU. During the Conference, 69 scientific communications from different branches of potential theory were presented; the majority of them are in­ cluded in the present volume. (Papers based on survey lectures delivered at the Conference, its program as well as a collection of problems from potential theory will appear in a special volume of the Lecture Notes Series published by Springer-Verlag). Topics of these communications truly reflect the vast scope of contemporary potential theory. Some contributions deal...

Supersymmetric approach for Killingbeck radial potential plus noncentral potential in Schrodinger equation

International Nuclear Information System (INIS)

Cari, C.; Suparmi, A.; Yunianto, M.; Pratiwi, B. N.

2016-01-01

Killingbeck radial potential, which consists of harmonic oscillator, linier and Coulomb potentials, is combined with non-central potential. The solution of three dimensional Schrodinger equation for Killingbeck potential is combined with Poschl-Teller potential and Symmetrical Top non-central potentials are investigated using supersymmetry (SUSY) operator. The non-relativistic energy is obtained which is infuenced by potentials and the wave functions are produced by using SUSY operator. (paper)

Auto fluorescence of intervertebral disc tissue: a new diagnostic tool.

Science.gov (United States)

Hoell, T; Huschak, G; Beier, A; Hüttmann, G; Minkus, Y; Holzhausen, H J; Meisel, H J

2006-08-01

The paper reports on auto fluorescence phenomena of inter-vertebral human discs. It systematically investigates the auto fluorescence effects of ex vivo disc specimen and reports on surgical cases to demonstrate the potential value of the new method. The paper offers biologic explanations of the phenomenon and discusses the potential value of the UV auto fluorescence technique as a diagnostic tool. Intra- and postoperative observations are made by a surgical microscope with an integrated UV light source. Quantitative measurements were carried out using a photon counter and a spectrometer ex vivo. The auto fluorescence phenomenon allows the differentiation of traumatized and degenerated disc tissue intraoperatively in some cases, it allows the differentiation of bony and collagen endplate in cervical disc surgery. The source of the auto fluorescent light emission are amino acids of the collagen molecules. The proteoglycan components and the liquid components of the disc do not show relevant auto fluorescence. Emission wavelength of disc material is equivalent to color perception. It differs due to different collagen composition of the intervertebral disc components from yellow-green to blue-green and can be visualized in situ by naked eye.UV-auto fluorescence of inter-vertebral discs is a new clinical tool that has the potential to differentiate disc material from the anatomical surrounding, to distinguish between different fractions of the disc and to give information on the quality and status of the disc material. Since the technology has just emerged, it needs further investigations to quantify the clinical observations reported in this paper.

Phthalate Metabolites, Consumer Habits and Health Effects

Directory of Open Access Journals (Sweden)

Peter Wallner

2016-07-01

Full Text Available Phthalates are multifunctional chemicals used in a wide variety of consumer products. The aim of this study was to investigate whether levels of urinary phthalate metabolites in urine samples of Austrian mothers and their children were associated with consumer habits and health indicators. Within an Austrian biomonitoring survey, urine samples from 50 mother-child pairs of five communities (two-stage random stratified sampling were analysed. The concentrations of 14 phthalate metabolites were determined, and a questionnaire was administered. Monoethyl phthalate (MEP, mono-n-butyl phthalate (MnBP, mono-isobutyl phthalate (MiBP, monobenzyl phthalate (MBzP, mono-(2-ethylhexyl phthalate (MEHP, mono-(2-ethyl-5-hydroxyhexyl phthalate (5OH-MEHP, mono-(2-ethyl-5-oxohexyl phthalate (5oxo-MEHP, mono-(5-carboxy-2-ethylpentyl phthalate (5cx-MEPP, and 3-carboxy-mono-propyl phthalate (3cx-MPP could be quantified in the majority of samples. Significant correlations were found between the use of hair mousse, hair dye, makeup, chewing gum, polyethylene terephthalate (PET bottles and the diethyl phthalate (DEP metabolite MEP. With regard to health effects, significant associations of MEP in urine with headache, repeated coughing, diarrhoea, and hormonal problems were observed. MBzP was associated with repeated coughing and MEHP was associated with itching.

Phthalate Metabolites, Consumer Habits and Health Effects.

Science.gov (United States)

Wallner, Peter; Kundi, Michael; Hohenblum, Philipp; Scharf, Sigrid; Hutter, Hans-Peter

2016-07-15

Phthalates are multifunctional chemicals used in a wide variety of consumer products. The aim of this study was to investigate whether levels of urinary phthalate metabolites in urine samples of Austrian mothers and their children were associated with consumer habits and health indicators. Within an Austrian biomonitoring survey, urine samples from 50 mother-child pairs of five communities (two-stage random stratified sampling) were analysed. The concentrations of 14 phthalate metabolites were determined, and a questionnaire was administered. Monoethyl phthalate (MEP), mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP), monobenzyl phthalate (MBzP), mono-(2-ethylhexyl) phthalate (MEHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (5OH-MEHP), mono-(2-ethyl-5-oxohexyl) phthalate (5oxo-MEHP), mono-(5-carboxy-2-ethylpentyl) phthalate (5cx-MEPP), and 3-carboxy-mono-propyl phthalate (3cx-MPP) could be quantified in the majority of samples. Significant correlations were found between the use of hair mousse, hair dye, makeup, chewing gum, polyethylene terephthalate (PET) bottles and the diethyl phthalate (DEP) metabolite MEP. With regard to health effects, significant associations of MEP in urine with headache, repeated coughing, diarrhoea, and hormonal problems were observed. MBzP was associated with repeated coughing and MEHP was associated with itching.

Confidence-building and Canadian leadership

International Nuclear Information System (INIS)

Cleminson, F.R.

1998-01-01

Confidence-building has come into its own as a 'tool of choice' in facilitating the non-proliferation, arms control and disarmament (NACD) agenda, whether regional or global. From the Middle East Peace Process (MEPP) to the ASEAN Intersessional Group on Confidence-Building (ARF ISG on CBMS), confidence-building has assumed a central profile in regional terms. In the Four Power Talks begun in Geneva on December 9, 1997, the United States identified confidence-building as one of two subject areas for initial discussion as part of a structured peace process between North and South Korea. Thus, with CBMs assuming such a high profile internationally, it seems prudent for Canadians to pause and take stock of the significant role which Canada has already played in the conceptual development of the process over the last two decades. Since the Helsinki accords of 1975, Canada has developed a significant expertise in this area through an unbroken series of original, basic research projects. These have contributed to defining the process internationally from concept to implementation. Today, these studies represent a solid and unique Departmental investment in basic research from which to draw in meeting Canada's current commitments to multilateral initiatives in the area of confidence-building and to provide a 'step up' in terms of future-oriented leadership. (author)

Calculation of baryon chemical potential and strangeness chemical potential in resonance matter

International Nuclear Information System (INIS)

Fu Yuanyong; Hu Shouyang; Lu Zhongdao

2006-01-01

Based on the high energy heavy-ion collisions statistical model, the baryon chemical potential and strangeness chemical potential are calculated for resonance matter with net baryon density and net strangeness density under given temperature. Furthermore, the relationship between net baryon density, net strangeness density and baryon chemical potential, strangeness chemical potential are analyzed. The results show that baryon chemical potential and strangeness chemical potential increase with net baryon density and net strangeness density increasing, the change of net baryon density affects baryon chemical potential and strangeness chemical potential more strongly than the change of net strangeness density. (authors)

Pumping potential wells

International Nuclear Information System (INIS)

Hershkowitz, N.; Forest, C.; Wang, E.Y.; Intrator, T.

1987-01-01

Nonmonotonic plasma potential structures are a common feature of many double layers and sheaths. Steady state plasma potential wells separating regions having different plasma potentials are often found in laboratory experiments. In order to exist, such structures all must find a solution to a common problem. Ions created by charge exchange or ionization in the region of the potential well are electrostatically confined and tend to accumulate and fill up the potential well. The increase in positive charge should eliminate the well, but steady state structures are found in which the wells do not fill up. This means that it is important to take into account processes which 'pump' ions from the well. As examples of ion pumping of plasma wells, potential dips in front of a positively biased electron collecting anode in a relatively cold, low density multidipole plasma are considered. Pumping is provided by ion leaks from the edges of the potential dip or by oscillating the applied potential. In the former case the two dimensional character of the problem is shown to be important. (author)

Pumping potential wells

Science.gov (United States)

Hershkowitz, N.; Forest, C.; Wang, E. Y.; Intrator, T.

1987-01-01

Nonmonotonic plasma potential structures are a common feature of many double layers and sheaths. Steady state plasma potential wells separating regions having different plasma potentials are often found in laboratory experiments. In order to exist, such structures all must find a solution to a common problem. Ions created by charge exchange or ionization in the region of the potential well are electrostatically confined and tend to accumulate and fill up the potential well. The increase in positive charge should eliminate the well. Nevertheless, steady state structures are found in which the wells do not fill up. This means that it is important to take into account processes which 'pump' ions from the well. As examples of ion pumping of plasma wells, potential dips in front of a positively biased electro collecting anode in a relatively cold, low density multidipole plasma is considered. Pumping is provided by ion leaks from the edges of the potential dip or by oscillating the applied potential. In the former case the two dimensional character of the problem is shown to be important.

Pumping potential wells

International Nuclear Information System (INIS)

Hershkowitz, N.; Forest, C.; Wang, E.Y.; Intrator, T.

1987-01-01

Nonmonotonic plasma potential structures are a common feature of many double layers and sheaths. Steady state plasma potential wells separating regions having different plasma potentials are often found in laboratory experiments. In order to exist, all such structures must find a solution to a common problem. Ions created by charge exchange or ionization in the region of the potential well are electrostatically confined and tend to accumulate and fill up the potential well. The increase in positive charge should eliminate the well. Nevertheless, steady state structures are found in which the wells do not fill up. This means that it is important to take into account processes which pump ions from the well. As examples of ion pumping of plasma wells, potential dips in front of a positively biased electron collecting anode in a relatively cold, low density, multidipole plasma are considered. Pumping is provided by ion leaks from the edges of the potential dip or by oscillating the applied potential. In the former case the two-dimensional character of the problem is shown to be important

Prevalence of degenerative and spondyloarthritis-related magnetic resonance imaging findings in the spine and sacroiliac joints in patients with persistent low back pain.

Science.gov (United States)

Arnbak, Bodil; Jensen, Tue S; Egund, Niels; Zejden, Anna; Hørslev-Petersen, Kim; Manniche, Claus; Jurik, Anne G

2016-04-01

To estimate the prevalence of degenerative and spondyloarthritis (SpA)-related magnetic resonance imaging (MRI) findings in the spine and sacroiliac joints (SIJs) and analyse their association with gender and age in persistent low back pain (LBP) patients. Degenerative and SpA-related MRI findings in the whole spine and SIJs were evaluated in Spine Centre patients aged 18-40 years with LBP. Among the 1,037 patients, the prevalence of disc degeneration, disc contour changes and vertebral endplate signal (Modic) changes were 87 % (±SEM 1.1), 82 % (±1.2) and 48 % (±1.6). All degenerative spinal findings were most frequent in men and patients aged 30-40 years. Spinal SpA-related MRI findings were rare. In the SIJs, 28 % (±1.4) had at least one MRI finding, with bone marrow oedema being the most common (21 % (±1.3)). SIJ erosions were most prevalent in patients aged 18-29 years and bone marrow oedema in patients aged 30-40 years. SIJ sclerosis and fatty marrow deposition were most common in women. SIJ bone marrow oedema, sclerosis and erosions were most frequent in women indicating pregnancy-related LBP. The high prevalence of SIJ MRI findings associated with age, gender, and pregnancy-related LBP need further investigation of their clinical importance in LBP patients. • The location of vertebral endplate signal changes supports a mechanical aetiology. • Several sacroiliac joint findings were associated with female gender and pregnancy-related back pain. • Sacroiliac joint bone marrow oedema was frequent and age-associated, indicating a possible degenerative aetiology. • More knowledge of the clinical importance of sacroiliac joint MRI findings is needed.

Lumbar disc arthroplasty: indications, biomechanics, types, and radiological criteria

International Nuclear Information System (INIS)

Baur-Melnyk, A.; Reiser, M.F.; Birkenmaier, C.

2006-01-01

Lumbar total disc replacement (TDR) was developed to treat a painful degenerative lumbar motion segment while avoiding the disadvantages of fusion surgery, such as adjacent segment instabilities. Early clinical results with TDR have shown a significant reduction in low back pain and a significant improvement in disability scores. When compared to fusion, the results with TDR tend to be superior in the short-term follow-up and initial rehabilitation is faster. The radiological assessment is an integral part of the preoperative work-up. Plain X-rays of the lumbar spine should be complemented by flexion - extension views in order to assess residual segmental mobility. Computed tomography is used to exclude osteoarthritis of the zygapophyseal joints, Baastrup's disease (kissing spines) and other sources of low back pain. Magnetic resonance imaging is useful to exclude substantial disc protrusions; it allows for the detection of disc dehydration and bone marrow edema in the case of activated spondylochondrosis. If osteoporosis is suspected, an osteodensitometry of the lumbar spine should be performed. Postoperative plain X-rays should include antero-posterior and lateral views as well as flexion - extension views in the later postoperative course. Measurements should determine the disc space height in the lateral view, the segmental and total lumbar lordosis as well as the segmental mobility in the flexion - extension views. The ideal position of a TDR is exactly central in the ap-view and close to the dorsal border of the vertebral endplates in the lateral view. Malpositioning may cause segmental hyperlordosis and unbalanced loading of the endplates with the risk of implant subsidence and migration. (orig.) [de

Correlation between Lumbar Lordosis Angle and Degree of Gynoid Lipodystrophy (Cellulite) in Asymptomatic Women

Science.gov (United States)

Milani, Giovana Barbosa; Filho, A’Dayr Natal; João, Sílvia Maria Amado

2008-01-01

INTRODUCTION Gynoid lipodystrophy (cellulite) has been cited as a common dermatological alteration. It occurs mainly in adult women and tends to gather around the thighs and buttocks. Its presence and severity have been related to many factors, including biotype, age, sex, circulatory changes, and, as some authors have suggested, mechanical alterations such as lumbar hyperlordosis. OBJECTIVE To correlate the degree of cellulite with the angle of lumbar lordosis in asymptomatic women. METHODS Fifty volunteers were evaluated by digital photos, palpation, and thermograph. The degree of cellulite was classified on a scale of 1–4. Analyses were performed on the superior, inferior, right and left buttocks (SRB, IRB, SLB, ILB), and the superior right and left thighs (SRT, SLT). The volunteers underwent a lateral-view X-ray, and the angle of lumbar lordosis was measured using Cobb’s method (inferior endplate of T12 and the superior endplate of S). The data were statistically analyzed using ANOVA and Spearman’s correlation. A significance level of 5% was adopted. RESULTS Volunteers had a mean age of 26.1 ± 4.4 years and a mean body mass index of 20.7 ± 1.9 kg/m2. There was no significant difference in lumbar lordosis angle between those with cellulite classes 2 and 3 (p ≥ 0.297). There was also no correlation between lumbar lordosis angle and the degree of cellulite (p ≥ 0.085 and r ≥ 0.246). CONCLUSIONS The analysis suggests that there is no correlation between the degree of cellulite and the angle of lumbar lordosis as measured using Cobb’s method. PMID:18719762

Caudal lumbar vertebral fractures in California Quarter Horse and Thoroughbred racehorses.

Science.gov (United States)

Collar, E M; Zavodovskaya, R; Spriet, M; Hitchens, P L; Wisner, T; Uzal, F A; Stover, S M

2015-09-01

To gain insight into the pathophysiology of equine lumbar vertebral fractures in racehorses. To characterise equine lumbar vertebral fractures in California racehorses. Retrospective case series and prospective case-control study. Racehorse post mortem reports and jockey injury reports were retrospectively reviewed. Vertebral specimens from 6 racehorses affected with lumbar vertebral fractures and 4 control racehorses subjected to euthanasia for nonspinal fracture were assessed using visual, radiographic, computed tomography and histological examinations. Lumbar vertebral fractures occurred in 38 Quarter Horse and 29 Thoroughbred racehorses over a 22 year period, primarily involving the 5th and/or 6th lumbar vertebrae (L5-L6; 87% of Quarter Horses and 48% of Thoroughbreds). Lumbar vertebral fractures were the third most common musculoskeletal cause of death in Quarter Horses and frequently involved a jockey injury. Lumbar vertebral specimens contained anatomical variations in the number of vertebrae, dorsal spinous processes and intertransverse articulations. Lumbar vertebral fractures examined in 6 racehorse specimens (5 Quarter Horses and one Thoroughbred) coursed obliquely in a cranioventral to caudodorsal direction across the adjacent L5-L6 vertebral endplates and intervertebral disc, although one case involved only one endplate. All cases had evidence of abnormalities on the ventral aspect of the vertebral bodies consistent with pre-existing, maladaptive pathology. Lumbar vertebral fractures occur in racehorses with pre-existing pathology at the L5-L6 vertebral junction that is likely predisposes horses to catastrophic fracture. Knowledge of these findings should encourage assessment of the lumbar vertebrae, therefore increasing detection of mild vertebral injuries and preventing catastrophic racehorse and associated jockey injuries. © 2014 EVJ Ltd.

Risk factors for intervertebral instability assessed by temporal evaluation of the radiographs and reconstructed computed tomography images after L5-S1 single-level transforaminal interbody fusion: A retrospective study.

Science.gov (United States)

Kobayashi, Yoshiomi; Shinozaki, Yoshio; Takahashi, Yohei; Takaishi, Hironari; Ogawa, Jun

2017-01-01

Intervertebral instability risks following L5-S1 transforaminal lumbar interbody fusion (TLIF) and causes of bony bridge formation on computed tomography (CT) remain largely unknown. We evaluated the temporal changes on plain radiographs and reconstructed CT images from 178 patients who had undergone single-level L5-S1 TLIF between February 2011 and February 2015. We statistically analyzed temporal changes the L5-S1 angle on radiographs and intervertebral stability (IVS) at the last observation. Bony bridge formation between the L5-S1 vertebral bodies and the titanium cage subsidence were analyzed by using reconstructed CT. Preoperative L5-S1 angle in the non-IVS group was significantly greater than that in the IVS group. The cage subsidence was classified as follows: type A, both upper and lower endplates; type B, either endplate; or type C, no subsidence. Types B and C decreased over time, whereas type A increased after surgery. The bony bridges between vertebral bodies were found in 87.2% of patients, and 94.5% of all bony bridges were found only in the cage, not on the contralateral side. Our findings suggested that high preoperative L5-S1 angle increased the risk of intervertebral instability after TLIF. The L5-S1 angle decreased over time with increasing type A subsidence, and almost all bony bridges were found only in the cage. These results suggest that the vertebral bodies were stabilized because of cage subsidence, and final bony bridges were created. Methods to improve bony bridge creation are needed to obtain reliable L5-S1 intervertebral bone union. Copyright © 2016 Elsevier Ltd. All rights reserved.

Radioactive choline uptake in the isolated rat phrenic nerve-hemidiaphragm preparation. A biochemical and autoradiographic study

Energy Technology Data Exchange (ETDEWEB)

Veldsema-Currie, R.D.; van Marle, J.; Langemeijer, M.W.; Lind, A.; van Weeren-Kramer, J.

1984-10-01

When hemidiaphragms are stimulated via the phrenic nerve in the presence of 10 microM radioactive choline (Ch), the rate of radioactive Ch uptake in the endplate-rich area (EPA) is greater than that in the endplate-poor muscle (M). Ch uptake in the EPA is temperature-dependent, with a Q10 of 2.9 and an activation energy of 19.5 kcal/mol. It is inhibited in a Na+-depleted medium, in the absence of Ca2+, and by 10-20 microM hemicholinium-3 (HC-3) and it is not inhibited by alpha-bungarotoxin even when the muscle is completely paralyzed. In the absence of stimulation the rate of uptake in the EPA is slightly, but not significantly, greater than in M. Using autoradiography, we find an enhanced amount of isotope in the nerve terminals and their immediate vicinities compared with the muscle fibres, in both stimulated and unstimulated hemidiaphragms. There is no enhanced uptake of isotope into the nerve terminals in stimulated tissues in the presence of 26 microM HC-3. The uptake of isotope into the muscle is not altered by any of these treatments. There is a positive correlation between the initial rate of radioactive Ch uptake in the EPA and the amount of isotope in the nerve terminals (the mean corrected grain density above the nerve terminals). Without correcting for the large amount of diffusion that occurs, the ratio of the grain density above the synapses to that above the muscle fibres is 1.66 in tissue stimulated at 1 Hz, 1.04 in stimulated tissues in the presence of 26 microM HC-3, and 1.31 in unstimulated tissues.

Percutaneous intradiscal ozone (O3)-injection: an experimental study in canines

International Nuclear Information System (INIS)

Yu Zhijian; He Xiaofeng; Chen Yong; Zeng Qingle; Liu Chihong; Zhao Zhongqing; Lu Yong; Li Yanhao

2002-01-01

Objective: To evaluate the influence of ozone on normal nucleus pulpous and the safety of intradiscal ozone-injection for the treatment of herniated lumbar disc. Methods: Ozone was injected into selected lumbar discs (3 ml) and the para-spinal space (7 ml) with 20 G Chiba needle under fluoroscopy in five canines. The ozone concentration was 30 μg/ml and 50 μg/ml respectively. Two discs were selected for each concentration. Total 20 discs were injected. Three of the canines were given one-time ozone-injection and were sacrificed for pathology one week, one month and two months respectively after the procedure, and the other two canines were given two-time ozone-injection and were sacrificed one month and two months respectively after the procedure. The specimens including nucleus pulpous, end-plate, spinal cord, nerve root, and greater psoas muscle were observed macroscopically and microscopically. Results: No serious behavior abnormalities were observed in all animals. The atrophy of nucleus pulpous could be observed one month after ozone-injection due to significant reduction of water and extensive proliferation of collagenous fiber. The influence on the atrophy of nucleus pulpous demonstrated no apparent difference between the selected two concentrations of ozone, but was more apparent with two-time injection than that with one-time injection. The end-plates increased slightly or moderately in thickness in 16 simples and a few of fibers in greater psoas muscle suffered slight atrophy in 5 samples. Conclusion: It is suggested that percutaneous intradiscal ozone-injection is a safe method, and can cause gradual atrophy of nucleus pulpous. This study provides the evidence of the feasibility and value of this procedure's application in clinics

Generalized Rosenbluth potentials

International Nuclear Information System (INIS)

Hassan, M.H.A.

1977-05-01

It is shown that the coefficients of friction and diffusion of the Balescu-Lenard equation can be derived from two ''generalized Rosenbluth potentials'', which reduce to the standard Rosenbluth potentials if wave effects are neglected. The potentials are evaluated explicitly in the case of Maxwellian field particles. The dominant contribution of wave effects to the potentials is due to the interaction of electron field particles with ion sound waves

Indiana University high energy physics group, task C: Technical progress report, December 1, 1987-November 30, 1988

International Nuclear Information System (INIS)

Bower, C.R.; Heinz, R.M.; Mufson, S.L.

1988-01-01

The Indiana University High Energy Physics Group, Task C has been actively involved in the MACRO experiment at Gran Sasso during the current contract year. MACRO is a large US-Italian Monopole, Astrophysics, and Cosmic Ray Observatory being built under the Gran Sasso Mountain outside of Rome. Indiana University is in charge of the US software effort. We have been performing extensive Monte Carlo design and data analysis calculations. We are also doing development work on the MACRO liquid scintillator. We are setting up a Quality Assurance liquid scintillator laboratory in Frascati, Italy. We are producing vertical scintillator tank endplates and calibration boats in our machine shop

Characteristics of CANDU fuel bundles that caused pressure tube fretting at the bundle midplane

Energy Technology Data Exchange (ETDEWEB)

Dennier, D; Manzer, A M [Atomic Energy of Canada Ltd., Mississauga, ON (Canada); Koehn, E [Ontario Hydro, Toronto, ON (Canada)

1996-12-31

Detailed measurements on new bundles, and those that caused fretting during in- and out-reactor tests, have given insight into the factors responsible for fretting at the midplane of the inlet bundle. Bottom fuel elements that were attached near radial endplate spokes and had inboard bearing pads in the rolled joint cavity produced a significant portion of the observed fret marks. These elements are influenced by several driving forces that deflect the centre bearing pads towards the pressure tube surface. The evidence suggests that slight changes in bundle design may be possible to reduce pressure tube fretting. (author). 4 refs., 3 tabs., 8 figs.

Complicating autoimmune diseases in myasthenia gravis: a review

Science.gov (United States)

Nacu, Aliona; Andersen, Jintana Bunpan; Lisnic, Vitalie; Owe, Jone Furlund; Gilhus, Nils Erik

2015-01-01

Abstract Myasthenia gravis (MG) is a rare autoimmune disease of skeletal muscle endplates. MG subgroup is relevant for comorbidity, but usually not accounted for. MG patients have an increased risk for complicating autoimmune diseases, most commonly autoimmune thyroid disease, systemic lupus erythematosus and rheumatoid arthritis. In this review, we present concomitant autoimmune disorders associated with the different MG subgroups, and show how this influences treatment and prognosis. Concomitant MG should always be considered in patients with an autoimmune disorder and developing new neuromuscular weakness, fatigue or respiratory failure. When a second autoimmune disorder is suspected, MG should be included as a differential diagnosis. PMID:25915571

The Lambert-W step-potential – an exactly solvable confluent hypergeometric potential

Energy Technology Data Exchange (ETDEWEB)

Ishkhanyan, A.M., E-mail: aishkhanyan@gmail.com [Institute for Physical Research, NAS of Armenia, 0203 Ashtarak (Armenia); Armenian State Pedagogical University, 0010 Yerevan (Armenia); Institute of Physics and Technology, National Research Tomsk Polytechnic University, Tomsk 634050 (Russian Federation)

2016-02-15

We present an asymmetric step–barrier potential for which the one-dimensional stationary Schrödinger equation is exactly solved in terms of the confluent hypergeometric functions. The potential is given in terms of the Lambert W-function, which is an implicitly elementary function also known as the product logarithm. We present the general solution of the problem and consider the quantum reflection at transmission of a particle above this potential barrier. Compared with the abrupt-step and hyperbolic tangent potentials, which are reproduced by the Lambert potential in certain parameter and/or variable variation regions, the reflection coefficient is smaller because of the lesser steepness of the potential on the particle incidence side. Presenting the derivation of the Lambert potential we show that this is a four-parametric sub-potential of a more general five-parametric one also solvable in terms of the confluent hypergeometric functions. The latter potential, however, is a conditionally integrable one. Finally, we show that there exists one more potential the solution for which is written in terms of the derivative of a bi-confluent Heun function. - Highlights: • We introduce an asymmetric step-barrier potential for which the 1D Schrödinger equation is exactly solved in terms of confluent hypergeometric functions. • The potential is given in terms of the Lambert-function, which is an implicitly elementary function also known as the product logarithm. • This is a four-parametric specification of a more general five-parametric potential also solvable in terms of the confluent hypergeometric functions. • There exists one more potential the solution for which is written in terms of the derivative of a bi-confluent Heun function.

On the scalar potential models from the isospectral potential class

Energy Technology Data Exchange (ETDEWEB)

Lima, V. Gomes [Universidade Federal Rural do Rio de Janeiro, Seropedica, RJ (Brazil). Dept. de Fisica; Santos, V. Silva [Paraiba Univ., Campina Grande, PB (Brazil). Dept. de Engenharia Civil; Rodrigues, R. de Lima [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]. E-mail: rafaelr@cbpf.br

2001-10-01

The static field classical configuration in (1+1)-dimensions for new non-linear potential models is investigated from an isospectral potential class and the concept of bosonic zero mode solution. One of the models considered here has a static nontopological configuration with a single vacuum state, whose potential in the stability equation corresponds to broken a supersymmetry. (author)

Super periodic potential

Science.gov (United States)

Hasan, Mohammd; Mandal, Bhabani Prasad

2018-04-01

In this paper we introduce the concept of super periodic potential (SPP) of arbitrary order n, n ∈I+, in one dimension. General theory of wave propagation through SPP of order n is presented and the reflection and transmission coefficients are derived in their closed analytical form by transfer matrix formulation. We present scattering features of super periodic rectangular potential and super periodic delta potential as special cases of SPP. It is found that the symmetric self-similarity is the special case of super periodicity. Thus by identifying a symmetric fractal potential as special cases of SPP, one can obtain the tunnelling amplitude for a particle from such fractal potential. By using the formalism of SPP we obtain the close form expression of tunnelling amplitude of a particle for general Cantor and Smith-Volterra-Cantor potentials.

ICRF enhanced potentials

International Nuclear Information System (INIS)

Nelson, B.A.

1987-01-01

Ion-confining potentials in the Phaedrus tandem mirror are shown to be enhanced over Boltzmann-relations predicted values by radio-frequency (rf) waves in the ion cyclotron range of frequencies (ICRF). The ICRF enhanced potential is larger in the end cell with a lower passing density. Peak potential values decrease with increasing ion endloss current (or central cell density) for a constant rf capacitor bank voltage, and increase with increasing rf-capacitor bank voltage, for a constant ion endloss value (or central cell density). In fully axisymmetric operation, a potential peak is produced in an end cell by the central-cell rf, (with-out end-cell rf) and is found only in the end cell nearer the central-cell antenna. ICRF enhanced potentials are explained as an equilibrium between the electron-collisional filling-in rate and the electron pumping out rate provided by axial time-varying electric fields. Thermal barrier-like potential structures were found in the transition regions between the central cell and end cells, in the fully axisymmetric Phaedrus. Central-cell ICRF trapping effects combined with end-cell μΔ B forces create and pump the barrier potential wells

Compressive cervical pannus formation in a patient after 2-level disc arthroplasty: a rare complication treated with posterior instrumented fusion.

Science.gov (United States)

Brophy, Carl M; Hoh, Daniel J

2018-06-01

Cervical disc arthroplasty (CDA) has received widespread attention as an alternative to anterior fusion due to its similar neurological and functional improvement, with the advantage of preservation of segmental motion. As CDA becomes more widely implemented, the potential for unexpected device-related adverse events may be identified. The authors report on a 48-year-old man who presented with progressive neurological deficits 3 years after 2-level CDA was performed. Imaging demonstrated periprosthetic osteolysis of the vertebral endplates at the CDA levels, with a heterogeneously enhancing ventral epidural mass compressing the spinal cord. Diagnostic workup for infectious and neoplastic processes was negative. The presumptive diagnosis was an inflammatory pannus formation secondary to abnormal motion at the CDA levels. Posterior cervical decompression and instrumented fusion was performed without removal of the arthroplasty devices or the ventral epidural mass. Postoperative imaging at 2 months demonstrated complete resolution of the compressive pannus, with associated improvement in clinical symptoms. Follow-up MRI at > 6 months showed no recurrence of the pannus. At 1 year postoperatively, CT scanning revealed improvement in periprosthetic osteolysis. Inflammatory pannus formation may be an unexpected complication of abnormal segmental motion after CDA. This rare etiology of an epidural mass associated with an arthroplasty device should be considered, in addition to workup for other potential infectious or neoplastic mass lesions. In symptomatic individuals, compressive pannus lesions can be effectively treated with fusion across the involved segment without removal of the device.

Foxa1 and Foxa2 are required for formation of the intervertebral discs.

Directory of Open Access Journals (Sweden)

Jennifer A Maier

Full Text Available The intervertebral disc (IVD is composed of 3 main structures, the collagenous annulus fibrosus (AF, which surrounds the gel-like nucleus pulposus (NP, and hyaline cartilage endplates, which are attached to the vertebral bodies. An IVD is located between each vertebral body. Degeneration of the IVD is thought to be a major cause of back pain, a potentially chronic condition for which there exist few effective treatments. The NP forms from the embryonic notochord. Foxa1 and Foxa2, transcription factors in the forkhead box family, are expressed early during notochord development. However, embryonic lethality and the absence of the notochord in Foxa2 null mice have precluded the study of potential roles these genes may play during IVD formation. Using a conditional Foxa2 allele in conjunction with a tamoxifen-inducible Cre allele (ShhcreER(T2, we removed Foxa2 from the notochord of E7.5 mice null for Foxa1. Foxa1(-/-;Foxa2(c/c;ShhcreER(T2 double mutant animals had a severely deformed nucleus pulposus, an increase in cell death in the tail, decreased hedgehog signaling, defects in the notochord sheath, and aberrant dorsal-ventral patterning of the neural tube. Embryos lacking only Foxa1 or Foxa2 from the notochord were indistinguishable from control animals, demonstrating a functional redundancy for these genes in IVD formation. In addition, we provide in vivo genetic evidence that Foxa genes are required for activation of Shh in the notochord.

Foxa1 and Foxa2 Are Required for Formation of the Intervertebral Discs

Science.gov (United States)

Maier, Jennifer A.; Lo, YinTing; Harfe, Brian D.

2013-01-01

The intervertebral disc (IVD) is composed of 3 main structures, the collagenous annulus fibrosus (AF), which surrounds the gel-like nucleus pulposus (NP), and hyaline cartilage endplates, which are attached to the vertebral bodies. An IVD is located between each vertebral body. Degeneration of the IVD is thought to be a major cause of back pain, a potentially chronic condition for which there exist few effective treatments. The NP forms from the embryonic notochord. Foxa1 and Foxa2, transcription factors in the forkhead box family, are expressed early during notochord development. However, embryonic lethality and the absence of the notochord in Foxa2 null mice have precluded the study of potential roles these genes may play during IVD formation. Using a conditional Foxa2 allele in conjunction with a tamoxifen-inducible Cre allele (ShhcreERT2), we removed Foxa2 from the notochord of E7.5 mice null for Foxa1. Foxa1−/−;Foxa2c/c;ShhcreERT2 double mutant animals had a severely deformed nucleus pulposus, an increase in cell death in the tail, decreased hedgehog signaling, defects in the notochord sheath, and aberrant dorsal-ventral patterning of the neural tube. Embryos lacking only Foxa1 or Foxa2 from the notochord were indistinguishable from control animals, demonstrating a functional redundancy for these genes in IVD formation. In addition, we provide in vivo genetic evidence that Foxa genes are required for activation of Shh in the notochord. PMID:23383217

Potential bags

International Nuclear Information System (INIS)

Ferreira, P.L.; Tomio, L.

1992-01-01

In this paper, relativistic confining potential models, endowed with bag constants associated to volume energy terms, are investigated. In contrast to the usual bag model, these potential bags are distinguished by having smeared bag surfaces. Based on the dynamical assumptions underlying the fuzzy bag model, these bag constants are derived from the corresponding energy-momentum tensor. Explicit expressions for the single-quark energies and for the nucleon bag constant are obtained by means of an improved analytical version of the saddle-point variational method for the Dirac equation with confining power-law potentials of the scalar plus vector (S + V) or pure scalar (S) type

Application of potential

International Nuclear Information System (INIS)

Petris, L.

1979-01-01

This report summarizes the results obtained with the nucleon-nucleon potential presented previously for: 1) the deuteron properties and wave function, 2) a Hartree-Fock calculation on O 16 , and 3) the perturbation V-matrix and G-matrix results for the potential in relation to the results of other potentials and to saturation

Congenital myasthenic syndromes in two kinships with end-plate acetylcholine receptor and utrophin deficiency

DEFF Research Database (Denmark)

Sieb, J P; Dörfler, P; Tzartos, S

1998-01-01

We studied two families with five affected members suffering from ptosis and slowly progressive limb-girdle muscle weakness. All patients had abnormal decremental response on low-frequency nerve stimulation, but there were no repetitive responses to single stimuli. The patients improved on anti-a...

Quantum potential theory

CERN Document Server

Schürmann, Michael

2008-01-01

This volume contains the revised and completed notes of lectures given at the school "Quantum Potential Theory: Structure and Applications to Physics," held at the Alfried-Krupp-Wissenschaftskolleg in Greifswald from February 26 to March 10, 2007. Quantum potential theory studies noncommutative (or quantum) analogs of classical potential theory. These lectures provide an introduction to this theory, concentrating on probabilistic potential theory and it quantum analogs, i.e. quantum Markov processes and semigroups, quantum random walks, Dirichlet forms on C* and von Neumann algebras, and boundary theory. Applications to quantum physics, in particular the filtering problem in quantum optics, are also presented.

Effective potentials from complex simulations: a potential-matching algorithm and remarks on coarse-grained potentials

International Nuclear Information System (INIS)

Toth, Gergely

2007-01-01

The projection of complex interactions onto simple distance-dependent or angle-dependent classical mechanical functions is a long-standing theoretical challenge in the field of computational sciences concerning biomolecules, colloids, aggregates and simple systems as well. The construction of an effective potential may be based on theoretical assumptions, on the application of fitting procedures on experimental data and on the simplification of complex molecular simulations. Recently, a force-matching method was elaborated to project the data of Car-Parrinello ab initio molecular dynamics simulations onto two-particle classical interactions (Izvekov et al 2004 J. Chem. Phys. 120 10896). We have developed a potential-matching algorithm as a practical analogue of this force-matching method. The algorithm requires a large number of configurations (particle positions) and a single value of the potential energy for each configuration. We show the details of the algorithm and the test calculations on simple systems. The test calculation on water showed an example in which a similar structure was obtained for qualitatively different pair interactions. The application of the algorithm on reverse Monte Carlo configurations was tried as well. We detected inconsistencies in a part of our calculations. We found that the coarse graining of potentials cannot be performed perfectly both for the structural and the thermodynamic data. For example, if one applies an inverse method with an input of the pair-correlation function, it provides energetics data for the configurations uniquely. These energetics data can be different from the desired ones obtained by all atom simulations, as occurred in the testing of our potential-matching method

The potential of renewable energy

International Nuclear Information System (INIS)

Piot, M.

2007-01-01

This article presents and comments on definitions of the potential of renewable forms of energy and, in a second part, takes a look at the potentials mentioned in the energy perspectives published by the Swiss Federal Office of Energy (SFOE). The following potentials are looked at: technical potential, ecological potential, economic potential, exploitable and expected potentials, technical, economic and ecological expansion potentials, potential of particular technologies in Switzerland, exploitable and expected expansion potential. Four scenarios for expansion potential are briefly described

Eulerian velocity reconstruction in ideal atmospheric dynamics using potential vorticity and potential temperature

Science.gov (United States)

Blender, R.

2009-04-01

An approach for the reconstruction of atmospheric flow is presented which uses space- and time-dependent fields of density ?, potential vorticity Q and potential temperature Î& cedil;[J. Phys. A, 38, 6419 (2005)]. The method is based on the fundamental equations without approximation. The basic idea is to consider the time-dependent continuity equation as a condition for zero divergence of momentum in four dimensions (time and space, with unit velocity in time). This continuity equation is solved by an ansatz for the four-dimensional momentum using three conserved stream functions, the potential vorticity, potential temperature and a third field, denoted as ?-potential. In zonal flows, the ?-potential identifies the initial longitude of particles, whereas potential vorticity and potential temperature identify mainly meridional and vertical positions. Since the Lagrangian tracers Q, Î&,cedil; and ? determine the Eulerian velocity field, the reconstruction combines the Eulerian and the Lagrangian view of hydrodynamics. In stationary flows, the ?-potential is related to the Bernoulli function. The approach requires that the gradients of the potential vorticity and potential temperature do not vanish when the velocity remains finite. This behavior indicates a possible interrelation with stability conditions. Examples with analytical solutions are presented for a Rossby wave and zonal and rotational shear flows.

Nucleus--nucleus potential

International Nuclear Information System (INIS)

Jaqaman, H.R.

1977-01-01

The nucleus--nucleus interaction is studied within the framework of the generator coordinate method that permits an easy incorporation of the full effects of antisymmetrization. It is found that the interaction, as far as the elastic scattering problem is concerned, can be described by a simple effective potential that is equivalent to the original many-body (and hence non-local) problem. The potential is obtained by dividing the wavefunction into a long-range part and a short-range part and requiring the former to satisfy a Schroedinger equation. This enables avoiding dealing with the troublesome short-range part of the wavefunction and provides a direct link with the optical model so that the potential obtained here is equivalent to the real part of the optical potential (the imaginary part is not investigated). The effective potential is found to consist of three parts: an interaction term between the nucleons belonging to different nuclei, a kinetic energy term due to the change in the intrinsic kinetic energy of the system as a result of the antisymmetrization, and finally an l-dependent part. The kinetic energy term is found to be very repulsive and effectively gives a hard core, and is calculated for the α--α and 16 O-- 16 O cases. The full potential is calculated for the α--α case for the S, D, and G partial waves and then used to calculate the corresponding phase shifts that are then compared with experimental results and other microscopic calculations. Finally, some recent results and analyses of fusion and deep inelastic reactions are reviewed that seem to indicate the presence of a hard core in the nucleus--nucleus potential. Such a hard core is present in the potential obtained in the sudden approximation

Potential of a polygonal prism and lamina; Takakuchu men no potential

Energy Technology Data Exchange (ETDEWEB)

Koyama, S

1996-05-01

With the use of rectangular coordinates O-XYZ, the potential of a calculation point P is expressed in the form of a triple repeated integral of a density {sigma} at point Q in the mass. The potential at the density {sigma} assumed to be 1 is named the potential of a polygonal prism. Further, a double repeated integral with an integral concerning Z removed from the triple integral is named the potential of polygonal lamina. This potential can be expressed in a quadratic form (linear form) with 2nd order partial derivative (1st order partial derivative) as a coefficient. On the contrary, in order to extract the 1st/2nd order partial derivatives from this potential by partial differential, it requires partial differentiation with these partial derivatives considered to be a constant. The reason that they can be realized is attributable to the zero result of the linear form which has as the coefficient a 3rd order partial derivative concerning the variable of integration in a primitive function. If this relation is used, the integral calculation and description may be simplified. An explanation was given with examples enumerated so that these conditions might be understood.

Repeatability of Computerized Tomography-Based Anthropomorphic Measurements of Frailty in Patients With Pulmonary Fibrosis Undergoing Lung Transplantation.

Science.gov (United States)

McClellan, Taylor; Allen, Brian C; Kappus, Matthew; Bhatti, Lubna; Dafalla, Randa A; Snyder, Laurie D; Bashir, Mustafa R

To determine interreader and intrareader repeatability and correlations among measurements of computerized tomography-based anthropomorphic measurements in patients with pulmonary fibrosis undergoing lung transplantation. This was an institutional review board-approved, Health Insurance Portability and Accountability Act-compliant retrospective study of 23 randomly selected subjects (19 male and 4 female; median age = 69 years; range: 66-77 years) with idiopathic pulmonary fibrosis undergoing pulmonary transplantation, who had also undergone preoperative thoracoabdominal computerized tomography. Five readers of varying imaging experience independently performed the following cross-sectional area measurements at the inferior endplate of the L3 vertebral body: right and left psoas muscles, right and left paraspinal muscles, total abdominal musculature, and visceral and subcutaneous fat. The following measurements were obtained at the inferior endplate of T6: right and left paraspinal muscles with and without including the trapezius muscles and subcutaneous fat. Three readers repeated all measurements to assess intrareader repeatability. Intrareader repeatability was nearly perfect (interclass correlation coefficients = 0.99, P < 0.001). Interreader agreement was excellent across all 5 readers (interclass correlation coefficients: 0.71-0.99, P < 0.001). Coefficients of variance between measures ranged from 3.2%-6.8% for abdominal measurements, but were higher for thoracic measurements, up to 23.9%. Correlation between total paraspinal and total psoas muscle area was strong (r 2 = 0.67, P < 0.001). Thoracic and abdominal musculature had a weaker correlation (r 2 = 0.35-0.38, P < 0.001). Measures of thoracic and abdominal muscle and fat area are highly repeatable in patients with pulmonary fibrosis undergoing lung transplantation. Measures of muscle area are strongly correlated among abdominal locations, but inversely correlated between abdominal and thoracic locations

Validation of multigroup neutron cross sections and calculational methods for the advanced neutron source against the FOEHN critical experiments measurements

International Nuclear Information System (INIS)

Smith, L.A.; Gallmeier, F.X.; Gehin, J.C.

1995-05-01

The FOEHN critical experiment was analyzed to validate the use of multigroup cross sections and Oak Ridge National Laboratory neutronics computer codes in the design of the Advanced Neutron Source. The ANSL-V 99-group master cross section library was used for all the calculations. Three different critical configurations were evaluated using the multigroup KENO Monte Carlo transport code, the multigroup DORT discrete ordinates transport code, and the multigroup diffusion theory code VENTURE. The simple configuration consists of only the fuel and control elements with the heavy water reflector. The intermediate configuration includes boron endplates at the upper and lower edges of the fuel element. The complex configuration includes both the boron endplates and components in the reflector. Cross sections were processed using modules from the AMPX system. Both 99-group and 20-group cross sections were created and used in two-dimensional models of the FOEHN experiment. KENO calculations were performed using both 99-group and 20-group cross sections. The DORT and VENTURE calculations were performed using 20-group cross sections. Because the simple and intermediate configurations are azimuthally symmetric, these configurations can be explicitly modeled in R-Z geometry. Since the reflector components cannot be modeled explicitly using the current versions of these codes, three reflector component homogenization schemes were developed and evaluated for the complex configuration. Power density distributions were calculated with KENO using 99-group cross sections and with DORT and VENTURE using 20-group cross sections. The average differences between the measured values and the values calculated with the different computer codes range from 2.45 to 5.74%. The maximum differences between the measured and calculated thermal flux values for the simple and intermediate configurations are ∼ 13%, while the average differences are < 8%

Adjacent segment degeneration after lumbar spinal fusion: the impact of anterior column support: a randomized clinical trial with an eight- to thirteen-year magnetic resonance imaging follow-up.

Science.gov (United States)

Videbaek, Tina S; Egund, Niels; Christensen, Finn B; Grethe Jurik, Anne; Bünger, Cody E

2010-10-15

Randomized controlled trial. To analyze long-term adjacent segment degeneration (ASD) after lumbar fusion on magnetic resonance imaging and compare randomization groups with and without anterior column support. ASD can be a long-term complication after fusion. The prevalence and the cause of ASD are not well documented, but ASD are one of the main arguments for introducing the use of motion-preserving techniques as an alternative to fusion. Anterior lumbar interbody fusion combined with posterolateral lumbar fusion (ALIF+PLF) has been proved superior to posterolateral fusion alone regarding outcome and cost-effectiveness. Between 1996 and 1999, 148 patients with severe chronic low back pain were randomly selected for ALIF+PLF or for PLF alone. Ninety-five patients participated. ASD was examined on magnetic resonance imaging with regard to disc degeneration, disc herniation, stenosis, and endplate changes. Disc heights on radiographs taken at index surgery and at long-term follow-up were compared. Outcome was assessed by validated questionnaires. The follow-up rate was 76%. ASD was similar between randomization groups. In the total cohort, endplate changes were seen in 26% of the participants and correlated significantly with the presence of disc degeneration and disc herniation. Disc degeneration and dorsal disc herniation were the parameters registered most frequently and were significantly more pronounced at the first adjacent level than at the second and the third adjacent levels. Patients without disc height reduction over time were significantly younger than patients with disc height reduction. Disc degeneration and stenosis correlated significantly with outcome at the first adjacent level. The cause of the superior outcome in the group with anterior support is still unclear. Compared with the findings reported in the literature, the prevalence of ASD is likely to be in concordance with the expected changes in a nonoperated symptomatic population and therefore

Optically-Induced Neuronal Activity Is Sufficient to Promote Functional Motor Axon Regeneration In Vivo.

Directory of Open Access Journals (Sweden)

Patricia J Ward

Full Text Available Peripheral nerve injuries are common, and functional recovery is very poor. Beyond surgical repair of the nerve, there are currently no treatment options for these patients. In experimental models of nerve injury, interventions (such as exercise and electrical stimulation that increase neuronal activity of the injured neurons effectively enhance axon regeneration. Here, we utilized optogenetics to determine whether increased activity alone is sufficient to promote motor axon regeneration. In thy-1-ChR2/YFP transgenic mice in which a subset of motoneurons express the light-sensitive cation channel, channelrhodopsin (ChR2, we activated axons in the sciatic nerve using blue light immediately prior to transection and surgical repair of the sciatic nerve. At four weeks post-injury, direct muscle EMG responses evoked with both optical and electrical stimuli as well as the ratio of these optical/electrical evoked EMG responses were significantly greater in mice that received optical treatment. Thus, significantly more ChR2+ axons successfully re-innervated the gastrocnemius muscle in mice that received optical treatment. Sections of the gastrocnemius muscles were reacted with antibodies to Synaptic Vesicle Protein 2 (SV2 to quantify the number of re-occupied motor endplates. The number of SV2+ endplates was greater in mice that received optical treatment. The number of retrogradely-labeled motoneurons following intramuscular injection of cholera toxin subunit B (conjugated to Alexa Fluor 555 was greater in mice that received optical treatment. Thus, the acute (1 hour, one-time optical treatment resulted in robust, long-lasting effects compared to untreated animals as well as untreated axons (ChR2-. We conclude that neuronal activation is sufficient to promote motor axon regeneration, and this regenerative effect is specific to the activated neurons.

Evolution of the ischio-iliac lordosis during natural growth and its relation with the pelvic incidence.

Science.gov (United States)

Schlösser, Tom P C; Janssen, Michiel M A; Vrtovec, Tomaž; Pernuš, Franjo; Oner, F Cumhur; Viergever, Max A; Vincken, Koen L; Castelein, René M

2014-07-01

Human fully upright ambulation, with fully extended hips and knees, and the body's center of gravity directly above the hips, is unique in nature, and distinguishes humans from all other mammalians. This bipedalism is made possible by the development of a lordosis between the ischium and ilium; it allows to ambulate in this unique bipedal manner, without sacrificing forceful extension of the legs. This configuration in space introduces unique biomechanical forces with relevance for a number of spinal conditions. The aim of this study was to quantify the development of this lordosis between ischium and ilium in the normal growing and adult spine and to evaluate its correlation with the well-known clinical parameter, pelvic incidence. Consecutive series of three-dimensional computed tomography scans of the abdomen of 189 children and 310 adults without spino-pelvic pathologies were used. Scan indications were trauma screening or acute abdominal pathology. Using previously validated image processing techniques, femoral heads, center of the sacral endplate and the axes of the ischial bones were semi-automatically identified. A true sagittal view of the pelvis was automatically reconstructed, on which ischio-iliac angulation and pelvic incidence were calculated. The ischio-iliac angle was defined as the angle between the axes of the ischial bones and the line from the midpoint of the sacral endplate to the center of the femoral heads. A wide natural variation of the ischio-iliac angle (3°-46°) and pelvic incidence (14°-77°) was observed. Pearson's analysis demonstrated a significant correlation between the ischio-iliac angle and pelvic incidence (r = 0.558, P lordosis is unique in nature, is in harmonious continuity with the highly individual lumbar lordosis and defines the way the human spine is biomechanically loaded. The practical parameter that reflects this is the pelvic incidence; both values increase during growth and remain stable in adulthood.

The 'Lumbar Fusion Outcome Score' (LUFOS): a new practical and surgically oriented grading system for preoperative prediction of surgical outcomes after lumbar spinal fusion in patients with degenerative disc disease and refractory chronic axial low back pain.

Science.gov (United States)

Mattei, Tobias A; Rehman, Azeem A; Teles, Alisson R; Aldag, Jean C; Dinh, Dzung H; McCall, Todd D

2017-01-01

In order to evaluate the predictive effect of non-invasive preoperative imaging methods on surgical outcomes of lumbar fusion for patients with degenerative disc disease (DDD) and refractory chronic axial low back pain (LBP), the authors conducted a retrospective review of 45 patients with DDD and refractory LBP submitted to anterior lumbar interbody fusion (ALIF) at a single center from 2007 to 2010. Surgical outcomes - as measured by Visual Analog Scale (VAS/back pain) and Oswestry Disability Index (ODI) - were evaluated pre-operatively and at 6 weeks, 3 months, 6 months, and 1 year post-operatively. Linear mixed-effects models were generated in order to identify possible preoperative imaging characteristics (including bone scan/99mTc scintigraphy increased endplate uptake, Modic endplate changes, and disc degeneration graded according to Pfirrmann classification) which may be predictive of long-term surgical outcomes . After controlling for confounders, a combined score, the Lumbar Fusion Outcome Score (LUFOS), was developed. The LUFOS grading system was able to stratify patients in two general groups (Non-surgical: LUFOS 0 and 1; Surgical: LUFOS 2 and 3) that presented significantly different surgical outcomes in terms of estimated marginal means of VAS/back pain (p = 0.001) and ODI (p = 0.006) beginning at 3 months and continuing up to 1 year of follow-up. In conclusion,  LUFOS has been devised as a new practical and surgically oriented grading system based on simple key parameters from non-invasive preoperative imaging exams (magnetic resonance imaging/MRI and bone scan/99mTc scintigraphy) which has been shown to be highly predictive of surgical outcomes of patients undergoing lumbar fusion for treatment for refractory chronic axial LBP.

[Total cervical disk replacement--implant-specific approaches: keel implant (Prodisc-C intervertebral disk prosthesis)].

Science.gov (United States)

Korge, Andreas; Siepe, Christoph J; Heider, Franziska; Mayer, H Michael

2010-11-01

Dynamic intervertebral support of the cervical spine via an anterolateral approach using a modular artificial disk prosthesis with end-plate fixation by central keel fixation. Cervical median or mediolateral disk herniations, symptomatic cervical disk disease (SCDD) with anterior osseous, ligamentous and/or discogenic narrowing of the spinal canal. Cervical fractures, tumors, osteoporosis, arthrogenic neck pain, severe facet degeneration, increased segmental instability, ossification of posterior longitudinal ligament (OPLL), severe osteopenia, acute and chronic systemic, spinal or local infections, systemic and metabolic diseases, known implant allergy, pregnancy, severe adiposity (body mass index > 36 kg/m2), reduced patient compliance, alcohol abuse, drug abuse and dependency. Exposure of the anterior cervical spine using the minimally invasive anterolateral approach. Intervertebral fixation of retainer screws. Intervertebral diskectomy. Segmental distraction with vertebral body retainer and vertebral distractor. Removal of end-plate cartilage. Microscopically assisted decompression of spinal canal. Insertion of trial implant to determine appropriate implant size, height and position. After biplanar image intensifier control, drilling for keel preparation using drill guide and drill bit, keel-cut cleaner to remove bone material from the keel cut, radiologic control of depth of the keel cut using the corresponding position gauge. Implantation of original implant under lateral image intensifier control. Removal of implant inserter. Functional postoperative care and mobilization without external support, brace not used routinely, soft brace possible for 14 days due to postoperative pain syndromes. Implantation of 100 cervical Prodisc-C disk prostheses in 78 patients (average age 48 years) at a single center. Clinical and radiologic follow-up 24 months postoperatively. Significant improvement based on visual analog scale and Neck Disability Index. Radiologic

A computed tomographic anatomical study of the upper sacrum. Application for a user guide of pelvic fixation with iliosacral screws in adult spinal deformity.

Science.gov (United States)

Dubory, Arnaud; Bouloussa, Houssam; Riouallon, Guillaume; Wolff, Stéphane

2017-12-01

Widely used in traumatic pelvic ring fractures, the iliosacral (IS) screw technique for spino-pelvic fixation remains anecdotal in adult spinal deformity. The objective of this study was to assess anatomical variability of the adult upper sacrum and to provide a user guide of spino-pelvic fixation with IS screws in adult spinal deformity. Anatomical variability of the upper sacrum according to age, gender, height and weight was sought on 30 consecutive pelvic CT-scans. Thus, a user guide of spino-pelvic fixation with IS screws was modeled and assessed on ten CT-scans as described below. Two invariable landmarks usable during the surgical procedure were defined: point A (corresponding to the connector binding the IS screw to the spinal rod), equidistant from the first posterior sacral hole and the base of the S1 articular facet and 10 mm-embedded into the sacrum; point B (corresponding to the tip of the IS screw) located at the junction of the anterior third and middle third of the sacral endplate in the sagittal plane and at the middle of the endplate in the coronal plane. Point C corresponded to the intersection between the A-B direction and the external facet of the iliac wing. Three-dimensional reconstructions modeling the IS screw optimal direction according to the A-B-C straight line were assessed. Age had no effect on the anatomy of the upper sacrum. The distance between the base of the S1 superior articular facet and the top of the first posterior sacral hole was correlated with weight (r = 0.6; 95% CI [0.6-0.9]); p guide of spinopelvic fixation with IS screws seems to be reliable and reproducible independently of age, gender and morphologic characteristics but needs clinical assessment. Level IV.

Refinement of elastic, poroelastic, and osmotic tissue properties of intervertebral disks to analyze behavior in compression.

Science.gov (United States)

Stokes, Ian A F; Laible, Jeffrey P; Gardner-Morse, Mack G; Costi, John J; Iatridis, James C

2011-01-01

Intervertebral disks support compressive forces because of their elastic stiffness as well as the fluid pressures resulting from poroelasticity and the osmotic (swelling) effects. Analytical methods can quantify the relative contributions, but only if correct material properties are used. To identify appropriate tissue properties, an experimental study and finite element analytical simulation of poroelastic and osmotic behavior of intervertebral disks were combined to refine published values of disk and endplate properties to optimize model fit to experimental data. Experimentally, nine human intervertebral disks with adjacent hemi-vertebrae were immersed sequentially in saline baths having concentrations of 0.015, 0.15, and 1.5 M and the loss of compressive force at constant height (force relaxation) was recorded over several hours after equilibration to a 300-N compressive force. Amplitude and time constant terms in exponential force-time curve-fits for experimental and finite element analytical simulations were compared. These experiments and finite element analyses provided data dependent on poroelastic and osmotic properties of the disk tissues. The sensitivities of the model to alterations in tissue material properties were used to obtain refined values of five key material parameters. The relaxation of the force in the three bath concentrations was exponential in form, expressed as mean compressive force loss of 48.7, 55.0, and 140 N, respectively, with time constants of 1.73, 2.78, and 3.40 h. This behavior was analytically well represented by a model having poroelastic and osmotic tissue properties with published tissue properties adjusted by multiplying factors between 0.55 and 2.6. Force relaxation and time constants from the analytical simulations were most sensitive to values of fixed charge density and endplate porosity.

The antibiotic prevention and interventional treatment as well as medical imaging manifestations of rabbit discitis

International Nuclear Information System (INIS)

Sun Gang; Yuang Cheng; Huang Deqing; Dong Zhengjun

1999-01-01

Objective: To assess the role of antibiotic and interventional radiology in prevention and treatment of discitis and analyze the imaging manifestations of discitis. Methods: 24 rabbits were used to make discitis models, and were classified into 4 groups randomly, 6 cases per group: non-treatment group, prophylactic antibiotic group, therapeutic antibiotic group and interventional treatment group. In prophylactic antibiotics group, intravenous clindamycin was administered 3 day before inoculation of bacteria to disc. In therapeutic antibiotics group, 4-week course of intravenous antibiotics was commenced 1 week after the bacterial inoculation. In interventional treatment group, PLD were performed 1 week after the inoculation, with simultaneous intravenous antibiotics for a period of 1 week, 2 or 4 weeks after inoculation. The lumbar spines of all rabbits were examined by X-ray, CT, and MRI respectively. Needle biopsy of nuclear pulpous was obtained and experimental region of lumbar spine were removed for pathological examination. Results: In non-treatment group and therapeutic antibiotics group, all of the discs inoculated with bacteria developed radiographic and pathological evidence of discitis, including intervertebral space narrowing, inflammatory changes of disc tissue, and destruction of end-plates. In prophylactic antibiotics group, none of the discs developed radiographic and pathological evidences of discitis, the bacterial culture was negative. In interventional treatment group, disc narrowing was observed in medical image and fibrosis was found in nucleus region. There was no evidence of destruction of end-plate, the bacteria culture was negative. Conclusion: MRI is a relative sensitive method to detect discitis. Prophylactic antibiotics is a key measure to prevent discitis. The PLD treatment could hold back the pathological process of discitis. Once developed, intravenous antibiotic is unable to affect the course of discitis

Suppression of CHRN endocytosis by carbonic anhydrase CAR3 in the pathogenesis of myasthenia gravis.

Science.gov (United States)

Du, Ailian; Huang, Shiqian; Zhao, Xiaonan; Feng, Kuan; Zhang, Shuangyan; Huang, Jiefang; Miao, Xiang; Baggi, Fulvio; Ostrom, Rennolds S; Zhang, Yanyun; Chen, Xiangjun; Xu, Congfeng

2017-01-01

Myasthenia gravis is an autoimmune disorder of the neuromuscular junction manifested as fatigable muscle weakness, which is typically caused by pathogenic autoantibodies against postsynaptic CHRN/AChR (cholinergic receptor nicotinic) in the endplate of skeletal muscle. Our previous studies have identified CA3 (carbonic anhydrase 3) as a specific protein insufficient in skeletal muscle from myasthenia gravis patients. In this study, we investigated the underlying mechanism of how CA3 insufficiency might contribute to myasthenia gravis. Using an experimental autoimmune myasthenia gravis animal model and the skeletal muscle cell C2C12, we find that inhibition of CAR3 (the mouse homolog of CA3) promotes CHRN internalization via a lipid raft-mediated pathway, leading to accelerated degradation of postsynaptic CHRN. Activation of CAR3 reduces CHRN degradation by suppressing receptor endocytosis. CAR3 exerts this effect by suppressing chaperone-assisted selective autophagy via interaction with BAG3 (BCL2-associated athanogene 3) and by dampening endoplasmic reticulum stress. Collectively, our study illustrates that skeletal muscle cell CAR3 is critical for CHRN homeostasis in the neuromuscular junction, and its deficiency leads to accelerated degradation of CHRN and development of myasthenia gravis, potentially revealing a novel therapeutic approach for this disorder.

Presynaptic muscarinic receptors, calcium channels, and protein kinase C modulate the functional disconnection of weak inputs at polyinnervated neonatal neuromuscular synapses.

Science.gov (United States)

Santafe, M M; Garcia, N; Lanuza, M A; Tomàs, M; Besalduch, N; Tomàs, J

2009-04-01

We studied the relation among calcium inflows, voltage-dependent calcium channels (VDCC), presynaptic muscarinic acetylcholine receptors (mAChRs), and protein kinase C (PKC) activity in the modulation of synapse elimination. We used intracellular recording to determine the synaptic efficacy in dually innervated endplates of the levator auris longus muscle of newborn rats during axonal competition in the postnatal synaptic elimination period. In these dual junctions, the weak nerve terminal was potentiated by partially reducing calcium entry (P/Q-, N-, or L-type VDCC-specific block or 500 muM magnesium ions), M1- or M4-type selective mAChR block, or PKC block. Moreover, reducing calcium entry or blocking PKC or mAChRs results in unmasking functionally silent nerve endings that now recover neurotransmitter release. Our results show interactions between these molecules and indicate that there is a release inhibition mechanism based on an mAChR-PKC-VDCC intracellular cascade. When it is fully active in certain weak motor axons, it can depress ACh release and even disconnect synapses. We suggest that this mechanism plays a central role in the elimination of redundant neonatal synapses, because functional axonal withdrawal can indeed be reversed by mAChRs, VDCCs, or PKC block.

Soils - Potential Runoff

Data.gov (United States)

Kansas Data Access and Support Center — This digital spatial data set provides information on the spatial distribution of potential runoff-contributing areas in Kansas. Potential runoff-contributing areas...

State-dependent classical potentials

International Nuclear Information System (INIS)

D'Amico, M.

2001-01-01

As alternative treatment to the potential operators of standard quantum mechanics is presented. The method is derived from Bohm's mechanics. The operator scalar (V) and vector (A) potential functions are replaced by a quantum potential. It is argued that the classical potential is a special limiting case of a more general quantum potential. The theory is illustrated by deriving an equivalent single-particle equation for the i-th particle of an n-body Bohmian system. The resulting effective state-dependent potential holds the interaction between the single-particle self-wave ψ s and the environment wave ψ e of the n - 1 remaining particles. The effective state-dependent potential is offered as a resolution to the Aharonov-Bohm effect where the phase difference is shown to result from the presence of ψ e . Finally, the interaction between ψ s and ψ e is illustrated graphically

Improvement of economic potential estimation methods for enterprise with potential branch clusters use

Directory of Open Access Journals (Sweden)

V.Ya. Nusinov

2017-08-01

Full Text Available The research determines that the current existing methods of enterprise’s economic potential estimation are based on the use of additive, multiplicative and rating models. It is determined that the existing methods have a row of defects. For example, not all the methods take into account the branch features of the analysis, and also the level of development of the enterprise comparatively with other enterprises. It is suggested to level such defects by an account at the estimation of potential integral level not only by branch features of enterprises activity but also by the intra-account economic clusterization of such enterprises. Scientific works which are connected with the using of clusters for the estimation of economic potential are generalized. According to the results of generalization it is determined that it is possible to distinguish 9 scientific approaches in this direction: the use of natural clusterization of enterprises with the purpose of estimation and increase of region potential; the use of natural clusterization of enterprises with the purpose of estimation and increase of industry potential; use of artificial clusterization of enterprises with the purpose of estimation and increase of region potential; use of artificial clusterization of enterprises with the purpose of estimation and increase of industry potential; the use of artificial clusterization of enterprises with the purpose of clustering potential estimation; the use of artificial clusterization of enterprises with the purpose of estimation of clustering competitiveness potential; the use of natural (artificial clusterization for the estimation of clustering efficiency; the use of natural (artificial clusterization for the increase of level at region (industries development; the use of methods of economic potential of region (industries estimation or its constituents for the construction of the clusters. It is determined that the use of clusterization method in

Effective Kratzer and Coulomb potentials as limit cases of a multiparameter exponential-type potential

Energy Technology Data Exchange (ETDEWEB)

García-Ravelo, J., E-mail: g.ravelo@hotmail.com [Departamento de Física, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Edificio 9, Unidad Profesional Adolfo López Mateos, México D.F., 07738 (Mexico); Menéndez, A.; García-Martínez, J. [Departamento de Física, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Edificio 9, Unidad Profesional Adolfo López Mateos, México D.F., 07738 (Mexico); Schulze-Halberg, A. [Department of Mathematics and Actuarial Science and Department of Physics, Indiana University Northwest, 3400 Broadway, Gary, IN 46408 (United States)

2014-06-13

We show that the effective Kratzer and Coulomb potentials can be obtained by taking particular limits of a multiparameter exponential potential that was studied recently. Moreover, we demonstrate that the bound state solutions of the exponential potential reduce correctly to their well-known counterparts associated with the Kratzer and Coulomb potentials. As a byproduct, we obtain a new limit relation for the hypergeometric function. - Highlights: • Kratzer and Coulomb potentials are limit cases of an exponential-type potential. • From exact s-waves, approximate solutions for l-waves are obtained. • l-waves of the potential tend to the solutions of the Kratzer and Coulomb potentials. • A non-evident identity between hypergeometric functions is demonstrated.

Effective Kratzer and Coulomb potentials as limit cases of a multiparameter exponential-type potential

International Nuclear Information System (INIS)

García-Ravelo, J.; Menéndez, A.; García-Martínez, J.; Schulze-Halberg, A.

2014-01-01

We show that the effective Kratzer and Coulomb potentials can be obtained by taking particular limits of a multiparameter exponential potential that was studied recently. Moreover, we demonstrate that the bound state solutions of the exponential potential reduce correctly to their well-known counterparts associated with the Kratzer and Coulomb potentials. As a byproduct, we obtain a new limit relation for the hypergeometric function. - Highlights: • Kratzer and Coulomb potentials are limit cases of an exponential-type potential. • From exact s-waves, approximate solutions for l-waves are obtained. • l-waves of the potential tend to the solutions of the Kratzer and Coulomb potentials. • A non-evident identity between hypergeometric functions is demonstrated

Crown Fire Potential

Data.gov (United States)

Earth Data Analysis Center, University of New Mexico — Crown fire potential was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The...

Retail Spending Potential

Data.gov (United States)

City and County of Durham, North Carolina — This map shows the average household spending potential for retail goods in the United States in 2012. Spending potential data measures household consumer spending...

The Low Energy Antiproton Ring (LEAR) in its first year of operation

CERN Multimedia

1983-01-01

LEAR*) and its enclosure in the PS South Hall in 1983 shortly after the start of its particle physics programme. Visible (in red) are the 90 degree bending magnets consisting of 6 blocks each. Separated from the magnets by short straight sections are the quadrupole doublets (blue with read end-plates). The 4 long straight sections house large equipment like septa for injection/ejection, RF-cavities and later (since 1986) electron cooling and an internal target and its associated detector (JETSET experiment). Several small copper tubes spanning across the ring are coaxial lines transmitting the stochastic cooling signals from pickup to kicker. *)[see H.Koziol and D. Möhl, Phys. Rep. 403-404 (2004), p.271 and references therein

Ballooning modes on open magnetic field lines

International Nuclear Information System (INIS)

Hameiri, E.

1999-01-01

The ballooning instability on open magnetic field lines is given a thorough mathematical analysis. It is shown that resistive bounding ends (endplates) induce the same stability properties as insulating ends. When unstable, the maximal growth rate increases monotonically with boundary resistivity. An interchange instability may be present, and one necessary condition for its stability is that ∫dl/B be constant on pressure surfaces. (This is an equilibrium existence condition for systems with closed magnetic field lines.) Another necessary condition for interchange stability has the same form as in the closed line case. Precise necessary and sufficient stability criteria are given for various types of bounding ends, including insulating, resistive, and perfectly conducting. copyright 1999 American Institute of Physics

Pathogenesis of spinal cord involvement induced by lower cervical instability in rheumatoid spondylitis

Energy Technology Data Exchange (ETDEWEB)

Taniguchi, Hironobu; Kuwabara, Shigeru; Fukuda, Kenji; Kuroki, Tatsuji; Tajima, Naoya (Miyazaki Medical Coll., Kiyotake (Japan))

1994-07-01

To examine prognostic factors in rheumatoid arthritis (RA), plain radiography findings and magnetic resonance imaging (MRI) findings were compared with histopathological findings in 129 RA patients who had local or neurologic symptoms due to the cervical spine. All patients underwent plain radiography, and subdislocation more than 2 mm towards the anterior and posterior directions on plain radiographs was defined as instability. In predicting induction of instability of the inferior cervical spine and risk for spinal compression, erosion of the vertebral rim, as seen on plain X-rays, and irregular findings of the end-plate of the vertebral body and Gd-enhanced nodules around the intervertebral disk, as seen on MRI, seemed to be important. (N.K.).

Element bow profiles from new and irradiated CANDU fuel bundles

International Nuclear Information System (INIS)

Dennier, D.; Manzer, A.M.; Ryz, M.A.

1996-01-01

Improved methods of measuring element profiles on new CANDU fuel bundles were developed at the Sheridan Park Engineering Laboratory, and have now been applied in the hot cells at Whiteshell Laboratories. For the first time, the outer element profiles have been compared between new, out-reactor tested, and irradiated fuel elements. The comparison shows that irradiated element deformation is similar to that observed on elements in out-reactor tested bundles. In addition to the restraints applied to the element via appendages, the element profile appears to be strongly influenced by gravity and the end loads applied by local deformation of the endplate. Irradiation creep in the direction of gravity also tends to be a dominant factor. (author)

Radiation-induced osteochondroma of the T4 vertebra causing spinal cord compression

Energy Technology Data Exchange (ETDEWEB)

Gorospe, Luis; Madrid-Muniz, Carmen; Royo, Aranzazu; Garcia-Raya, Pilar [Department of Radiology, La Paz University Hospital, Madrid (Spain); Alvarez-Ruiz, Fernando [Department of Neurosurgery, La Paz University Hospital, Madrid (Spain); Lopez-Barea, Fernando [Department of Pathology, La Paz University Hospital, Madrid (Spain)

2002-04-01

A case of a radiation-induced osteochondroma arising from the vertebral body of T4 in an 18-year-old man is reported. The patient presented with a history of progressive left lower extremity weakness. At 7 years of age, he had undergone resection of a cerebellar medulloblastoma and received adjunctive craniospinal irradiation and systemic chemotherapy. Both CT and MR imaging revealed an extradural mass contiguous with the posteroinferior endplate of the T4 vertebral body. This case indicates that radiation-induced osteochondroma should be considered in the differential diagnosis of patients with symptoms of myelopathy or nerve root compression and a history of radiation therapy involving the spine in childhood. (orig.)

Lienard-Wiechert potentials as a consequence of Lorentz transformation of Coulomb potential

International Nuclear Information System (INIS)

Strel'tsov, V.N.

1993-01-01

A derivation of the electric potential of a moving charge as a result of the 'relativization' of the Coulomb potential is considered. The account of the Lorentz covariance demand and the action retardation of the electromagnetic field with necessity leads to the Lienard-Wiechert potentials. 11 refs. (author)

The Development Potential in the System of Potentials of an Industrial Enterprise

Directory of Open Access Journals (Sweden)

Shpak Sergiy O.

2018-03-01

Full Text Available The aim of the article is to clarify the content and formulate a methodologically rigorous definition of the concept of enterprise development as a key category of management theory for restructuring industrial enterprises that provides the basis for a constructive definition of the concept of development potential and its place in the system of enterprise potentials. It is substantiated that the interpretation of the concept of enterprise development that is consistent with the philosophical concept of development should accumulate the concepts of competitiveness of an enterprise, as the ability to generate an acceptable profit on a long-term basis; the potential of an enterprise, as the ability to perform its basic activity characterizing the cumulative result of such activity, its marginal opportunities; the role of the structure of the enterprise as a system in the formation of its ultimate capabilities (potentials. It is shown that these requirements are met by the definition of the development process as a process of a purposeful transfer of the enterprise to a qualitatively new state described by broader opportunities for generating profits under the forecast conditions. At the same time, the structural adaptation of the enterprise to the new operating conditions is a tool for realizing the development process, which indicates the equivalence of the concepts of structural adaptability of an enterprise and its development potential. It is substantiated that the competitiveness of an enterprise is determined by its economic potential and development potential, which form the highest level of the hierarchy of potentials, the construction of which is possible in the course of decomposition of these potentials into their components according to the type of activity of the enterprise.

Inhibition of protein kinase C affects on mode of synaptic vesicle exocytosis due to cholesterol depletion

Energy Technology Data Exchange (ETDEWEB)

Petrov, Alexey M., E-mail: fysio@rambler.ru; Zakyrjanova, Guzalija F., E-mail: guzik121192@mail.ru; Yakovleva, Anastasia A., E-mail: nastya1234qwer@mail.ru; Zefirov, Andrei L., E-mail: zefiroval@rambler.ru

2015-01-02

Highlights: • We examine the involvement of PKC in MCD induced synaptic vesicle exocytosis. • PKC inhibitor does not decrease the effect MCD on MEPP frequency. • PKC inhibitor prevents MCD induced FM1-43 unloading. • PKC activation may switch MCD induced exocytosis from kiss-and-run to a full mode. • Inhibition of phospholipase C does not lead to similar change in exocytosis. - Abstract: Previous studies demonstrated that depletion of membrane cholesterol by 10 mM methyl-beta-cyclodextrin (MCD) results in increased spontaneous exocytosis at both peripheral and central synapses. Here, we investigated the role of protein kinase C in the enhancement of spontaneous exocytosis at frog motor nerve terminals after cholesterol depletion using electrophysiological and optical methods. Inhibition of the protein kinase C by myristoylated peptide and chelerythrine chloride prevented MCD-induced increases in FM1-43 unloading, whereas the frequency of spontaneous postsynaptic events remained enhanced. The increase in FM1-43 unloading still could be observed if sulforhodamine 101 (the water soluble FM1-43 quencher that can pass through the fusion pore) was added to the extracellular solution. This suggests a possibility that exocytosis of synaptic vesicles under these conditions could occur through the kiss-and-run mechanism with the formation of a transient fusion pore. Inhibition of phospholipase C did not lead to similar change in MCD-induced exocytosis.

Biological evolution of replicator systems: towards a quantitative approach.

Science.gov (United States)

Martin, Osmel; Horvath, J E

2013-04-01

The aim of this work is to study the features of a simple replicator chemical model of the relation between kinetic stability and entropy production under the action of external perturbations. We quantitatively explore the different paths leading to evolution in a toy model where two independent replicators compete for the same substrate. To do that, the same scenario described originally by Pross (J Phys Org Chem 17:312-316, 2004) is revised and new criteria to define the kinetic stability are proposed. Our results suggest that fast replicator populations are continually favored by the effects of strong stochastic environmental fluctuations capable to determine the global population, the former assumed to be the only acting evolution force. We demonstrate that the process is continually driven by strong perturbations only, and that population crashes may be useful proxies for these catastrophic environmental fluctuations. As expected, such behavior is particularly enhanced under very large scale perturbations, suggesting a likely dynamical footprint in the recovery patterns of new species after mass extinction events in the Earth's geological past. Furthermore, the hypothesis that natural selection always favors the faster processes may give theoretical support to different studies that claim the applicability of maximum principles like the Maximum Metabolic Flux (MMF) or Maximum Entropy Productions Principle (MEPP), seen as the main goal of biological evolution.

Confidence-building and Canadian leadership

Energy Technology Data Exchange (ETDEWEB)

Cleminson, F.R. [Dept. of Foreign Affairs and International Trade, Verification, Non-Proliferation, Arms Control and Disarmament Div (IDA), Ottawa, Ontario (Canada)

1998-07-01

Confidence-building has come into its own as a 'tool of choice' in facilitating the non-proliferation, arms control and disarmament (NACD) agenda, whether regional or global. From the Middle East Peace Process (MEPP) to the ASEAN Intersessional Group on Confidence-Building (ARF ISG on CBMS), confidence-building has assumed a central profile in regional terms. In the Four Power Talks begun in Geneva on December 9, 1997, the United States identified confidence-building as one of two subject areas for initial discussion as part of a structured peace process between North and South Korea. Thus, with CBMs assuming such a high profile internationally, it seems prudent for Canadians to pause and take stock of the significant role which Canada has already played in the conceptual development of the process over the last two decades. Since the Helsinki accords of 1975, Canada has developed a significant expertise in this area through an unbroken series of original, basic research projects. These have contributed to defining the process internationally from concept to implementation. Today, these studies represent a solid and unique Departmental investment in basic research from which to draw in meeting Canada's current commitments to multilateral initiatives in the area of confidence-building and to provide a 'step up' in terms of future-oriented leadership. (author)

Diagnostico y tratamiento de la myasthenia gravis estudio de una poblacion hospitalaria

Directory of Open Access Journals (Sweden)

Roberto D. Rey

1990-09-01

Full Text Available Durante la observacion de 50 pacientes con Myasthenia gravis entre los anos 1974 y 1987 se encontro un predominio del sexo femenino en la proporcion de 2,5 a 1 y mayor frecuencia de presentacion en Ias 3ª y 5ª décadas de la vida. Luego de la evaluacion clínica, el diagnóstico fué confirmado mediante: (1 prueba dei edrofonio, (2 estímulo nervioso repetitivo, (3 dosaje de anticuerpos antirreceptor colinérgico y (4 transferencia pasiva del suero al raton con ulterior niedicion de la amplitud de mepp's. La positividad diagnostica vario entre el 90 y el 100%, segun el tipo de prueba empleada. El estúdio radiológico del timo fué hecho con neumomediastinografía. obteniendose excelente correlación con la descripcion histológica de la glândula, y con tomografia computada, que demostro menor eficiência diagnostica. El tratamiento fué implementado en base a anticolinesterásicos, timectomía y corticoterapia inmunosupresora, evidenciandose con esta última mejores resultados. Nueve pacientes desarrollaron peoria transitória del cuadro muscular al iniciarse el tratamiento esteroideo, 6 de ellos exhibieron posteriormente evolucion desfavorable. Esta observacion aparenta tener valor pronóstico en la evolucion de la MG.

Morse potential, symmetric Morse potential and bracketed bound-state energies

Czech Academy of Sciences Publication Activity Database

Znojil, Miloslav

2016-01-01

Roč. 31, č. 14 (2016), s. 1650088 ISSN 0217-7323 R&D Projects: GA ČR GA16-22945S Institutional support: RVO:61389005 Keywords : quantum bound states * special functions * Morse potential * symmetrized Morse potential * upper and lower energy estimates * computer-assisted symbolic manipulations Subject RIV: BE - Theoretical Physics Impact factor: 1.165, year: 2016

High-temperature axion potential

International Nuclear Information System (INIS)

Dowrick, N.J.; McDougall, N.A.

1989-01-01

We investigate the possibility of new terms in the high-temperature axion potential arising from the dynamical nature of the axion field and from higher-order corrections to the θ dependence in the free energy of the quark-gluon plasma. We find that the dynamical nature of the axion field does not affect the potential but that the higher-order effects lead to new terms in the potential which are larger than the term previously considered. However, neither the magnitude nor the sign of the potential can be calculated by a perturbative expansion of the free energy since the coupling is too large. We show that a change in the magnitude of the potential does not significantly affect the bound on the axion decay constant but that the sign of the potential is of crucial importance. By investigating the formal properties of the functional integral within the instanton dilute-gas approximation, we find that the sign of the potential does not change and that the minimum remains at θ=0. We conclude that the standard calculation of the axion energy today is not significantly modified by this investigation

Potential theory of radiation

International Nuclear Information System (INIS)

Chiu, Hueihuang.

1989-01-01

A theoretical method is being developed by which the structure of a radiation field can be predicted by a radiation potential theory, similar to a classical potential theory. The introduction of a scalar potential is justified on the grounds that the spectral intensity vector is irrotational. The vector is also solenoidal in the limits of a radiation field in complete radiative equilibrium or in a vacuum. This method provides an exact, elliptic type equation that will upgrade the accuracy and the efficiency of the current CFD programs required for the prediction of radiation and flow fields. A number of interesting results emerge from the present study. First, a steady state radiation field exhibits an optically modulated inverse square law distribution character. Secondly, the unsteady radiation field is structured with two conjugate scalar potentials. Each is governed by a Klein-Gordon equation with a frictional force and a restoring force. This steady potential field structure and the propagation of radiation potentials are consistent with the well known results of classical electromagnetic theory. The extension of the radiation potential theory for spray combustion and hypersonic flow is also recommended

The construction of partner potential from the general potential anharmonic in D-dimensional Schrodinger system

Science.gov (United States)

Suparmi; Cari, C.; Wea, K. N.; Wahyulianti

2018-03-01

The Schrodinger equation is the fundamental equation in quantum physics. The characteristic of the particle in physics potential field can be explained by using the Schrodinger equation. In this study, the solution of 4 dimensional Schrodinger equation for the anharmonic potential and the anharmonic partner potential have done. The method that used to solve the Schrodinger equation was the ansatz wave method, while to construction the partner potential was the supersymmetric method. The construction of partner potential used to explain the experiment result that cannot be explained by the original potential. The eigenvalue for anharmonic potential and the anharmonic partner potential have the same characteristic. Every increase of quantum orbital number the eigenvalue getting smaller. This result corresponds to Bohrn’s atomic theory that the eigenvalue is inversely proportional to the atomic shell. But the eigenvalue for the anharmonic partner potential higher than the eigenvalue for the anharmonic original potential.

Generalized magnetic Rosenbluth potentials

International Nuclear Information System (INIS)

Hassan, M.H.A.

1977-12-01

It is shown that the coefficients of friction and diffusion of the magnetized Balescu-Lenard equation describing the interaction of ion test particles with electron field particles can be derived from two scalar potentials, which reduce to the potentials derived previously when wave effects are neglected. The parts of the potentials describing ''wave effects'' are evaluated explicitly in the case of Maxwellian electrons and the results are compared with the unmagnetized Rosenbluth potentials. The correction is dominant when eta=Ωsub(e)/ωsub(e)(>)1

Potentials of biofuels

Energy Technology Data Exchange (ETDEWEB)

Munack, A.; Schroder, O. [Johann Heinrich von Thunen Inst., Braunschweig (Germany); Krahl, J. [Coburg Univ. of Applied Sciences, Coburg (Germany); Bunger, J. [Inst. for Prevention and Occupational Medicine of the German Social Accident Insurance, Ruhr-Univ. Inst., Bochum (Germany)

2010-07-01

This paper discussed the potential of biofuels with particular reference to the situation in Germany and Europe. Emphasis was on technical potential, such as biofuel production, utilization and environmental aspects. The Institute of Agricultural Technology and Biosystems Engineering ran vTI emission tests on diesel engines to evaluate the environmental impacts of biofuels. This testing facility is able to drive heavy-duty diesel engines in both stationary and dynamic test cycles, such as the European ESC and ETC. Additional analyses were conducted to determine the fine and ultra-fine particles, polycyclic aromatic hydrocarbons (PAH), aldehydes, ketones, and the usual regulated exhaust gas compounds. Ames tests were conducted to assess the mutagenic potential of tailpipe emissions. Previous study results showed that neat vegetable oils can render the exhaust high in mutagenic potency. Some of the non-regulated exhaust gas compounds were found to vary nonlinearly with the blend composition. B20 was found to have high mutagenic potential and was subject to sedimentation.

Handbook of interatomic potentials

International Nuclear Information System (INIS)

Stoneham, A.M.; Taylor, R.

1981-08-01

This Handbook collects together interatomic potentials for a large number of metals. Most of the potentials describe the interactions of host metal atoms with each other, and these, in some cases, may be applied to solid and liquid metals. In addition, there are potentials (a) for a metallic impurity alloyed with the host, (b) for a small number of chemical impurities in the metal (eg H, O), and (c) for rare-gas impurities, notably He. The Handbook is intended to be a convenient source of potentials for bulk, surface and defect calculations, both static and dynamic. (author)

Temperature effect on proximal to distal gradient of quantal release of acetylcholine at frog endplate

Czech Academy of Sciences Publication Activity Database

Samigullin, D.; Bukharaeva, E.; Nikolsky, E.; Vyskočil, František

2003-01-01

Roč. 28, 3-4 (2003), s. 507-514 ISSN 0364-3190 R&D Projects: GA AV ČR IAA7011902; GA ČR GA305/02/1333; GA ČR GA202/02/1213 Grant - others:RFBR(RU) 02/04/48901 Institutional research plan: CEZ:AV0Z5011922; CEZ:MSM 113100003 Keywords : neuromuscular junction * acetylcholine release * temperature Subject RIV: ED - Physiology Impact factor: 1.511, year: 2003

Directly patching high-level exchange-correlation potential based on fully determined optimized effective potentials

Science.gov (United States)

Huang, Chen; Chi, Yu-Chieh

2017-12-01

The key element in Kohn-Sham (KS) density functional theory is the exchange-correlation (XC) potential. We recently proposed the exchange-correlation potential patching (XCPP) method with the aim of directly constructing high-level XC potential in a large system by patching the locally computed, high-level XC potentials throughout the system. In this work, we investigate the patching of the exact exchange (EXX) and the random phase approximation (RPA) correlation potentials. A major challenge of XCPP is that a cluster's XC potential, obtained by solving the optimized effective potential equation, is only determined up to an unknown constant. Without fully determining the clusters' XC potentials, the patched system's XC potential is "uneven" in the real space and may cause non-physical results. Here, we developed a simple method to determine this unknown constant. The performance of XCPP-RPA is investigated on three one-dimensional systems: H20, H10Li8, and the stretching of the H19-H bond. We investigated two definitions of EXX: (i) the definition based on the adiabatic connection and fluctuation dissipation theorem (ACFDT) and (ii) the Hartree-Fock (HF) definition. With ACFDT-type EXX, effective error cancellations were observed between the patched EXX and the patched RPA correlation potentials. Such error cancellations were absent for the HF-type EXX, which was attributed to the fact that for systems with fractional occupation numbers, the integral of the HF-type EXX hole is not -1. The KS spectra and band gaps from XCPP agree reasonably well with the benchmarks as we make the clusters large.

Decoupling Action Potential Bias from Cortical Local Field Potentials

Directory of Open Access Journals (Sweden)

Stephen V. David

2010-01-01

Full Text Available Neurophysiologists have recently become interested in studying neuronal population activity through local field potential (LFP recordings during experiments that also record the activity of single neurons. This experimental approach differs from early LFP studies because it uses high impendence electrodes that can also isolate single neuron activity. A possible complication for such studies is that the synaptic potentials and action potentials of the small subset of isolated neurons may contribute disproportionately to the LFP signal, biasing activity in the larger nearby neuronal population to appear synchronous and cotuned with these neurons. To address this problem, we used linear filtering techniques to remove features correlated with spike events from LFP recordings. This filtering procedure can be applied for well-isolated single units or multiunit activity. We illustrate the effects of this correction in simulation and on spike data recorded from primary auditory cortex. We find that local spiking activity can explain a significant portion of LFP power at most recording sites and demonstrate that removing the spike-correlated component can affect measurements of auditory tuning of the LFP.

Overview of interatomic potentials

International Nuclear Information System (INIS)

Bonny, G.; Malerba, L.

2005-12-01

In this report an overview on interatomic potentials is given. This overview is by no means complete and it has merely the intention to give the reader an idea of where interatomic potentials come from, as well as to provide the basic ideas behind some commonly used methods for deriving interatomic potentials for molecular dynamics applications. We start by giving a short introduction about the concept of interatomic potential in the framework of quantum mechanics, followed by a short description of commonly used methods for deriving semi-empirical interatomic potentials. After some short theoretical notions on each method, some practical parameterizations of commonly used potentials are given, including very recent ones. An effort has been made to classify existing approaches within a rational and consequent scheme, which is believed to be of use for a thorough comprehension of the topic. Although these approaches can be used in a variety of different materials, we will only discuss the practical cases of metals. Following this, some widespread ad hoc modification of the general methods are discussed. The report is concluded by a generalization of the methods to multi-component materials, in particular metallic alloys. (author)

Temperature dependence in interatomic potentials and an improved potential for Ti

International Nuclear Information System (INIS)

Ackland, G J

2012-01-01

The process of deriving an interatomic potentials represents an attempt to integrate out the electronic degrees of freedom from the full quantum description of a condensed matter system. In practice it is the derivatives of the interatomic potentials which are used in molecular dynamics, as a model for the forces on a system. These forces should be the derivative of the free energy of the electronic system, which includes contributions from the entropy of the electronic states. This free energy is weakly temperature dependent, and although this can be safely neglected in many cases there are some systems where the electronic entropy plays a significant role. Here a method is proposed to incorporate electronic entropy in the Sommerfeld approximation into empirical potentials. The method is applied as a correction to an existing potential for titanium. Thermal properties of the new model are calculated, and a simple method for fixing the melting point and solid-solid phase transition temperature for existing models fitted to zero temperature data is presented.

Ion ejection from a permanent-magnet mini-helicon thruster

Energy Technology Data Exchange (ETDEWEB)

Chen, Francis F. [Electrical Engineering Department, University of California, Los Angeles 90095-1594 (United States)

2014-09-15

A small helicon source, 5 cm in diameter and 5 cm long, using a permanent magnet (PM) to create the DC magnetic field B, is investigated for its possible use as an ion spacecraft thruster. Such ambipolar thrusters do not require a separate electron source for neutralization. The discharge is placed in the far-field of the annular PM, where B is fairly uniform. The plasma is ejected into a large chamber, where the ion energy distribution is measured with a retarding-field energy analyzer. The resulting specific impulse is lower than that of Hall thrusters but can easily be increased to relevant values by applying to the endplate of the discharge a small voltage relative to spacecraft ground.

M6-C artificial disc placement.

Science.gov (United States)

Coric, Domagoj; Parish, John; Boltes, Margaret O

2017-01-01

There has been a steady evolution of cervical total disc replacement (TDR) devices over the last decade resulting in surgical technique that closely mimics anterior cervical discectomy and fusion as well as disc design that emphasizes quality of motion. The M6-C TDR device is a modern-generation artificial disc composed of titanium endplates with tri-keel fixation as well as a polyethylene weave with a polyurethane core. Although not yet approved by the FDA, M6-C has finished a pilot and pivotal US Investigational Device Exemption (IDE) study. The authors present the surgical technique for implantation of a 2-level M6-C cervical TDR device. The video can be found here: https://youtu.be/rFEAqINLRCo .

An extract of lionfish (Pterois volitans) spine tissue contains acetylcholine and a toxin that affects neuromuscular transmission.

Science.gov (United States)

Cohen, A S; Olek, A J

1989-01-01

A soluble toxic extract derived from spine tissue of the lionfish (Pterois volitans) decreased heart rate and force of contraction in isolated clam and frog hearts. These actions were due to the presence of micromolar concentrations of acetylcholine in the extract. Toxicity was retained after hydrolysis of acetylcholine by exogenous acetylcholinesterase, but heart function was no longer affected. Toxin treated in this way induced muscle fibrillation in an isolated nerve-muscle preparation, followed by blockade of neuromuscular transmission. Bursts of transient depolarizations were recorded at the muscle endplate shortly after toxin addition that correlated in time with the duration of toxin-induced muscle fibrillation. These effects are thought to be due to the increased release and then depletion of acetylcholine from the nerve terminal.

Interstitial cells of Cajal in the striated musculature of the mouse esophagus

DEFF Research Database (Denmark)

Rumessen, J J; de Kerchove d'Exaerde, A; Mignon, S

2001-01-01

. Sections and whole-mounts were studied by immunohistochemistry. KitW-lacZ transgenic mice, which carry the lacZ reporter gene inserted in place of the first exon of the Kit gene, were processed for Xgal histochemistry, for quantitative analysis and for ultrastructural studies. Spindle-shaped ICC were...... scarce in both muscle layers of the thoracic esophagus, while their number increased steeply toward the cardia in the striated portion of the intraabdominal esophagus. They did not form networks and had no relationship with intrinsic myenteric ganglia and motor end-plates. They were often close to nerve...... between striated muscle cells in the mouse esophagus. They are close to nerves with defined neurochemical coding and could possibly represent specialized esophageal spindle proprioceptors....

Effect of blades number to performance of Savonius water turbine in water pipe

Science.gov (United States)

Hamzah, Imron; Prasetyo, Ari; Tjahjana, D. D. D. Prija; Hadi, Syamsul

2018-02-01

Savonius is usually known as a wind turbine that works efficiently at low wind speed. In this research, the Savonius turbine is proposed for a pico hydro power plant that is installed straightly on the 3-inch vertical pipeline of rainwater and household waste. The Savonius water turbine was designed with blade curvature angle of 70°, the aspect ratio of 1, turbine diameter of 82 mm, and endplate ratio of 1,1. The experimental study investigated the effect of blades number to the performance of Savonius turbine on various volume flow rate of water. Savonius turbine with three blades number generated the highest coefficient of performance of 0.23 on tip speed ratio of 1.7 compared to turbines with the number of other blades.

Pair potentials in liquid metals

International Nuclear Information System (INIS)

Faber, T.E.

1980-01-01

The argument which justifies the use of a pair potential to describe the structure-dependent term in the energy of liquid metals is briefly reviewed. Because there is an additional term in the energy which depends upon volume rather than structure, and because the pair potential itself is volume-dependent, the relationship between pair potential and observable properties such as pressure, bulk modulus and pair distribution function is more complicated for liquid metals than it is for molecular liquids. Perhaps for this reason, the agreement between pair potentials inferred from observable properties and pair potentials calculated by means of pseudo-potential theory is still far from complete. The pair potential concept is applicable only to simple liquid metals, in which the electron-ion interaction is weak. No attempt is made to discuss liquid transition and rare-earth metals, which are not simple in this sense. (author)

Potentials of surfaces in space

International Nuclear Information System (INIS)

Whipple, E.C.

1981-01-01

The potential of a body in space is determined by a balance between various charging currents such as the transfer of charge from plasma particles, photoemission, and secondary electron emission. These processes are evaluated for bodies in the solar system and in interstellar space under the headings; an overview of charging, survey of early work on charging, charging processes, effects of non-isotropic plasmas and magnetic and electric fields, calculation of surface potentials, differential charging, potential barriers and discharge processes, measurements of potential, potential modification and control on spacecraft, and astrophysical applications. (U.K.)

Measurement of proton autoneutralization potential

International Nuclear Information System (INIS)

Garcia, M.

1984-09-01

A proton space charge having multi-MeV kinetic energy was injected through a thin ground plane to extract electrons and produce a time-dependent autoneutralization space potential. An electon-emitting floating-potential resistive divider was used to measure the space potential during 20 ns of the proton current pulse. During this time, proton kinetic energy fell from 10.6 MeV to 8.5 MeV and thus the space potential (taken as 1.09 x the floating potential) fell from 5.8 kV to 4.6 kV

Violent Potentials

DEFF Research Database (Denmark)

Mikkelsen, Henrik Hvenegaard; Søgaard, Thomas Friis

2015-01-01

” plays a critical role in relation to Bugkalot men’s construction of hegemonic masculinity and the sustaining of complex egalitarian relations. The Bugkalot have a notoriously violent history; until the late 1970s more than half of the adult men engaged in ritual killings. While most Bugkalot men has...... that can also be used in other contexts to understand how men construct hegemonic masculinity by strategically adopting the interspace of civility and violence.......This article explores the social significance of violence as potentiality and performance among former headhunters. Taking its outset in an ethnographic study of violence and masculinity among the Philippine people known as the Bugkalot, we explore how violence as “performed violent potentiality...

An improved potential for krypton

International Nuclear Information System (INIS)

Aziz, R.A.

1979-01-01

An improved potential for krypton is presented. It has the simple but realistic form used by Aziz and Chen for argon based on the HFD potential suggested by Ahlrichs et.al. The potential, with known long-range behaviour, was fitted to second virial, viscosity and thermal conductivity data. The potential appears to have the best overall predictive ability for dilute gas, bulk and microscopic data. (author)

Deep attractive NN potential as a potential for the N(1440)-N system

International Nuclear Information System (INIS)

Glozman, L.Y.; Kukulin, V.I.; Pomerantsev, V.N.

1992-01-01

This work demonstrates that the model of a deep attractive NN potential (the Moscow NN potential) with a deep lying extra state may be interpreted as a potential in the N(1440)-N system. Under such an interpretation, the deep-lying level forbidden for the NN system describes the N(1440)-N component in deuteron. This conclusion is used to obtain the momentum distribution for the N(1440)-N component in deuteron

On the dynamics of gauge potential

International Nuclear Information System (INIS)

Tao Jiafu; Li Yuanjie; Zhang Jinru

1992-01-01

The gauge potential is resolved into gauge potential of strength and gauge potential of phase. The phase gauge potential can be described with an equivalent potential of inertial force. A Lagrangian density with phase gauge potential is given and some examples are discussed. The method proposed has been extended to the case of the non-Abelian group

Towards a Kohn-Sham potential via the optimized effective-potential method

International Nuclear Information System (INIS)

Norman, M.R.; Koelling, D.D.

1984-01-01

The optimized effective-potential (OEP) method is applied to a self-interaction-corrected local-spin-density (SIC-LSD) energy functional. The local potential which results has the useful properties of being both self-interaction free and orbital independent, and it can thus be regarded as a good approximation to the exact Kohn-Sham potential. A number of atomic systems are examined in the exchange-only and in the Ceperley-Alder exchange-correlation approximations. The resulting total energies are very close to those obtained by previous applications of the LSD-SIC functional. The resultant potentials are structurally similar to those derived by applying the OEP method to a Hartree-Fock Hamiltonian: showing much improved behavior over the local-spin-density approximation in both large- and small-r regions as well as the characteristic intershell cusplike structure. The eigenvalues have less formal significance than the more standard approaches, especially those for unoccupied orbitals which seem to have no significance whatsoever. Nonetheless, the highest occupied eigenvalue agrees closely with the conventional LSD-SIC value. However, for the deeper levels, each eigenvalue lies higher than the comparable eigenvalue of the conventional SIC, although lower than the eigenvalue of the LSD potential: the deeper the level, the larger the difference. This property follows from the nonvariational character of the eigenvalues, and it is shown that one can obtain realistic excitation spectra from this formalism by utilizing the appropriate variational quantity. The results obtained illustrate some of the less understood issues in the application of the Kohn-Sham procedure within density-functional theory

Abuse Potential of Pregabalin

DEFF Research Database (Denmark)

Schjerning, Ole; Rosenzweig, Mary; Pottegård, Anton

2016-01-01

BACKGROUND: Several case reports and epidemiological studies have raised concern about the abuse potential of pregabalin, the use of which has increased substantially over the last decade. Pregabalin is, in some cases, used for recreational purposes and it has incurred attention among drug abusers...... for causing euphoric and dissociative effects when taken in doses exceeding normal therapeutic dosages or used by alternative routes of administration, such as nasal insufflation or venous injection. The magnitude of the abuse potential and the mechanism behind it are not fully known. OBJECTIVE: The aim...... of this study was to present a systematic review of the data concerning the abuse potential of pregabalin. METHODS: We performed a systematic literature search and reviewed the preclinical, clinical and epidemiological data on the abuse potential of pregabalin. RESULTS: We included preclinical (n = 17...

Skin denervation does not alter cortical potentials to surface concentric electrode stimulation: A comparison with laser evoked potentials and contact heat evoked potentials.

Science.gov (United States)

La Cesa, S; Di Stefano, G; Leone, C; Pepe, A; Galosi, E; Alu, F; Fasolino, A; Cruccu, G; Valeriani, M; Truini, A

2018-01-01

In the neurophysiological assessment of patients with neuropathic pain, laser evoked potentials (LEPs), contact heat evoked potentials (CHEPs) and the evoked potentials by the intraepidermal electrical stimulation via concentric needle electrode are widely agreed as nociceptive specific responses; conversely, the nociceptive specificity of evoked potentials by surface concentric electrode (SE-PREPs) is still debated. In this neurophysiological study we aimed at verifying the nociceptive specificity of SE-PREPs. We recorded LEPs, CHEPs and SE-PREPs in eleven healthy participants, before and after epidermal denervation produced by prolonged capsaicin application. We also used skin biopsy to verify the capsaicin-induced nociceptive nerve fibre loss in the epidermis. We found that whereas LEPs and CHEPs were suppressed after capsaicin-induced epidermal denervation, the surface concentric electrode stimulation of the same denervated skin area yielded unchanged SE-PREPs. The suppression of LEPs and CHEPs after nociceptive nerve fibre loss in the epidermis indicates that these techniques are selectively mediated by nociceptive system. Conversely, the lack of SE-PREP changes suggests that SE-PREPs do not provide selective information on nociceptive system function. Capsaicin-induced epidermal denervation abolishes laser evoked potentials (LEPs) and contact heat evoked potentials (CHEPs), but leaves unaffected pain-related evoked potentials by surface concentric electrode (SE-PREPs). These findings suggest that unlike LEPs and CHEPs, SE-PREPs are not selectively mediated by nociceptive system. © 2017 European Pain Federation - EFIC®.

Classification of geothermal resources by potential

Science.gov (United States)

Rybach, L.

2015-03-01

When considering and reporting resources, the term "geothermal potential" is often used without clearly stating what kind of potential is meant. For renewable energy resources it is nowadays common to use different potentials: theoretical, technical, economic, sustainable, developable - decreasing successively in size. In such a sequence, the potentials are progressively realizable and more and more rewarding financially. The theoretical potential describes the physically present energy, the technical potential the fraction of this energy that can be used by currently available technology and the economic potential the time- and location-dependent fraction of the previous category; the sustainable potential constrains the fraction of the economic potential that can be utilized in the long term; the developable potential is the fraction of the economic resource which can be developed under realistic conditions. In converting theoretical to technical potential, the recovery factor (the ratio extractable heat/heat present at depth) is of key importance. An example (global geothermal resources) is given, with numerical values of the various potentials. The proposed classification could and should be used as a kind of general template for future geothermal energy resources reporting.

Comparative study of displacement cascades simulated with ‘magnetic’ potentials and Mendelev-type potential in α-Fe

Energy Technology Data Exchange (ETDEWEB)

Gao, Chan, E-mail: gaochan@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); School of Graduate, China Academy of Engineering Physics, Mianyang 621900 (China); Tian, Dongfeng [China Academy of Engineering Physics, Mianyang 621900 (China); Li, Maosheng [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Qian, Dazhi [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

2017-04-15

Different interatomic potentials produce displacement cascades with different features, and hence they significantly influence the results obtained from the displacement cascade simulations. The displacement cascade simulations in α-Fe have been carried out by molecular dynamics with three ‘magnetic’ potentials (MP) and Mendelev-type potential in this paper. Prior to the cascade simulations, the ‘magnetic’ potentials are hardened to suit for cascade simulations. We find that the peak time, maximum of defects, cascade volume and cascade density with ‘magnetic’ potentials are smaller than those with Mendelev-type potential. There is no significant difference within statistical uncertainty in the defect production efficiency with Mendelev-type potential and the second ‘magnetic’ potential at the same cascade energy, but remarkably smaller than those with the first and third ‘magnetic’ potential. Self interstitial atom (SIA) clustered fractions with ‘magnetic’ potentials are smaller than that with Mendelev-type potential, especially at the higher energy, due to the larger interstitial formation energies which result from the ‘magnetic’ potentials. The defect clustered fractions, which are input data for radiation damage accumulation models, may influence the prediction of microstructural evolution under radiation.

Impact of climate change on maize potential productivity and the potential productivity gap in southwest China

Science.gov (United States)

He, Di; Wang, Jing; Dai, Tong; Feng, Liping; Zhang, Jianping; Pan, Xuebiao; Pan, Zhihua

2014-12-01

The impact of climate change on maize potential productivity and the potential productivity gap in Southwest China (SWC) are investigated in this paper. We analyze the impact of climate change on the photosynthetic, light-temperature, and climatic potential productivity of maize and their gaps in SWC, by using a crop growth dynamics statistical method. During the maize growing season from 1961 to 2010, minimum temperature increased by 0.20°C per decade ( p gap between light-temperature and climatic potential productivity varied from 12 to 2729 kg ha-1, with the high value areas centered in northern and southwestern SWC. Climatic productivity of these areas reached only 10%-24% of the light-temperature potential productivity, suggesting that there is great potential to increase the maize potential yield by improving water management in these areas. In particular, the gap has become larger in the most recent 10 years. Sensitivity analysis shows that the climatic potential productivity of maize is most sensitive to changes in temperature in SWC. The findings of this study are helpful for quantification of irrigation water requirements so as to achieve maximum yield potentials in SWC.

The imaginary part of the local potential equivalent to the non-local α-nucleus optical potential

International Nuclear Information System (INIS)

Lassaut, M.; Vinh Mau, N.

1982-01-01

A simple expression of the α-nucleus optical potential has been derived from the Feshbach formula by using a closure approximation for summing over the excited states of the target nucleus. It has been shown that the correction to the real folding model potential is small. The imaginary local potential equivalent to the non-local Feshbach potential has been studied in detail for Ca nuclei and shown to reproduce quite well the gross properties of empirical potentials above 100 MeV with, however, a lack of absorption in the surface region. The A-dependence of the imaginary potential volume integral has also been investigated. (orig.)

Groundwater Potential

African Journals Online (AJOL)

big timmy

4Department of Geology, Ekiti State University, Ado-Ekiti, Nigeria. Corresponding ... integrated for the classification of the study area into different groundwater potential zones. .... table is mainly controlled by subsurface movement of water into ...

Forecasting potential crises

International Nuclear Information System (INIS)

Neufeld, W.P.

1984-01-01

Recently, the Trend Analysis Program (TAP) of the American Council of Life Insurance commissioned the Futures Group of Glastonbury, Connecticut, to examine the potential for large-scale catastrophic events in the near future. TAP was specifically concerned with five potential crises: the warming of the earth's atmosphere, the water shortage, the collapse of the physical infrastructure, the global financial crisis, and the threat of nuclear war. We are often unprepared to take action; in these cases, we lose an advantage we might have otherwise had. This is the whole idea behind forecasting: to foresee possibilities and to project how we can respond. If we are able to create forecasts against which we can test policy options and choices, we may have the luxury of adopting policies ahead of events. Rather than simply fighting fires, we have the option of creating a future more to our choosing. Short descriptions of these five potential crises and, in some cases, possible solutions are presented

Examining Management Success Potential.

Science.gov (United States)

Quatrano, Louis A.

The derivation of a model of management success potential in hospitals or health services administration is described. A questionnaire developed to assess management success potential in health administration students was voluntarily completed by approximately 700 incoming graduate students in 35 university health services administration programs…

Instantons and the interquark potential

International Nuclear Information System (INIS)

McDougall, N.A.

1980-01-01

It is argued that the contributions to the interquark potential from instantons of all scale sizes may be calculated in a consistent, cut-off-independent manner using the dilute-gas approximation; and that an interquark potential dominated at intermediate distances by these contributions is similar to already successful phenomenological potentials. (orig.)

Long-term potentiation (LTP) of human sensory-evoked potentials.

Science.gov (United States)

Kirk, Ian J; McNair, Nicolas A; Hamm, Jeffrey P; Clapp, Wesley C; Mathalon, Daniel H; Cavus, Idil; Teyler, Timothy J

2010-09-01

Long-term potentiation (LTP) is the principal candidate synaptic mechanism underlying learning and memory, and has been studied extensively at the cellular and molecular level in laboratory animals. Inquiry into the functional significance of LTP has been hindered by the absence of a human model as, until recently, LTP has only been directly demonstrated in humans in isolated cortical tissue obtained from patients undergoing surgery, where it displays properties identical to those seen in non-human preparations. In this brief review, we describe the results of paradigms recently developed in our laboratory for inducing LTP-like changes in visual-, and auditory-evoked potentials. We describe how rapid, repetitive presentation of sensory stimuli leads to a persistent enhancement of components of sensory-evoked potential in normal humans. Experiments to date, investigating the locus, stimulus specificity, and NMDA receptor dependence of these LTP-like changes suggest that they have the essential characteristics of LTP seen in experimental animals. The ability to elicit LTP from non-surgical patients will provide a human model system allowing the detailed examination of synaptic plasticity in normal subjects and may have future clinical applications in the assessment of cognitive disorders. Copyright © 2010 John Wiley & Sons, Ltd. For further resources related to this article, please visit the WIREs website. Copyright © 2010 John Wiley & Sons, Ltd.

Redox potential distribution of an organic-rich contaminated site obtained by the inversion of self-potential data

Science.gov (United States)

Abbas, M.; Jardani, A.; Soueid Ahmed, A.; Revil, A.; Brigaud, L.; Bégassat, Ph.; Dupont, J. P.

2017-11-01

Mapping the redox potential of shallow aquifers impacted by hydrocarbon contaminant plumes is important for the characterization and remediation of such contaminated sites. The redox potential of groundwater is indicative of the biodegradation of hydrocarbons and is important in delineating the shapes of contaminant plumes. The self-potential method was used to reconstruct the redox potential of groundwater associated with an organic-rich contaminant plume in northern France. The self-potential technique is a passive technique consisting in recording the electrical potential distribution at the surface of the Earth. A self-potential map is essentially the sum of two contributions, one associated with groundwater flow referred to as the electrokinetic component, and one associated with redox potential anomalies referred to as the electroredox component (thermoelectric and diffusion potentials are generally negligible). A groundwater flow model was first used to remove the electrokinetic component from the observed self-potential data. Then, a residual self-potential map was obtained. The source current density generating the residual self-potential signals is assumed to be associated with the position of the water table, an interface characterized by a change in both the electrical conductivity and the redox potential. The source current density was obtained through an inverse problem by minimizing a cost function including a data misfit contribution and a regularizer. This inversion algorithm allows the determination of the vertical and horizontal components of the source current density taking into account the electrical conductivity distribution of the saturated and non-saturated zones obtained independently by electrical resistivity tomography. The redox potential distribution was finally determined from the inverted residual source current density. A redox map was successfully built and the estimated redox potential values correlated well with in

Effective pair potentials for spherical nanoparticles

International Nuclear Information System (INIS)

Van Zon, Ramses

2009-01-01

An effective description for rigid spherical nanoparticles in a fluid of point particles is presented. The points inside the nanoparticles and the point particles are assumed to interact via spherically symmetric additive pair potentials, while the distribution of points inside the nanoparticles is taken to be spherically symmetric and smooth. The resulting effective pair interactions between a nanoparticle and a point particle, as well as between two nanoparticles, are then given by spherically symmetric potentials. If overlap between particles is allowed, as can occur for some forms of the pair potentials, the effective potential generally has non-analytic points. It is shown that for each effective potential the expressions for different overlapping cases can be written in terms of one analytic auxiliary potential. Even when only non-overlapping situations are possible, the auxiliary potentials facilitate the formulation of the effective potentials. Effective potentials for hollow nanoparticles (appropriate e.g. for buckyballs) are also considered and shown to be related to those for solid nanoparticles. For hollow nanoparticles overlap is more physical, since this covers the case of a smaller particle embedded in a larger, hollow nanoparticle. Finally, explicit expressions are given for the effective potentials derived from basic pair potentials of power law and exponential form, as well as from the commonly used London–van der Waals, Morse, Buckingham, and Lennard-Jones potentials. The applicability of the latter is demonstrated by comparison with an atomic description of nanoparticles with an internal face centered cubic structure

Exactly solvable energy-dependent potentials

International Nuclear Information System (INIS)

Garcia-Martinez, J.; Garcia-Ravelo, J.; Pena, J.J.; Schulze-Halberg, A.

2009-01-01

We introduce a method for constructing exactly-solvable Schroedinger equations with energy-dependent potentials. Our method is based on converting a general linear differential equation of second order into a Schroedinger equation with energy-dependent potential. Particular examples presented here include harmonic oscillator, Coulomb and Morse potentials with various types of energy dependence.

The hydrogeothermal potential of Southern Hesse; Das hydrogeothermische Potential Suedhessens

Energy Technology Data Exchange (ETDEWEB)

Fitzer, C; Fluhrer, S; Sanner, B; Knoblich, K [Giessen Univ. (Germany). Inst. fuer Angewandte Geowissenschaften

1997-12-01

The paper investigates rock series suited as storage media and the temperature distribution in the subsurface of Southern Hesse. It gives an idea of the possibilities for hydrogeothermal energy use in the area. The densily populated Rhein-Main-region provides a good demand potential for geothermal heat. A substantially elevated geothermal gradient of about 60 K/km as compared to the continental average of 30 K/km could be demonstrated in the northern part of the Upper Rhine Graben. Thermal anomalies could be localised. The Rotliegend-layers (Perm) provide the highest geothermal ressources in the region. In more shallow depth, the Hydrobia layers (Teritary) show reasonable values. To the north, the potential of these series decreases. Hence hydrogeothermal energy use should not be considered in the northern part of Southern Hesse. The highest potential can be expected from the Rotliegend layers in the area of Stockstadt and Biebesheim. (orig.) [Deutsch] Die Untersuchung geht auf die moeglichen Speichergesteine und die Temperaturverteilung im Untergrund Suedhessens ein und gibt einen ersten Eindruck von den Moeglichkeiten zur Nutzung der Hydrogeothermie in der Region. Fuer geothermische Waerme besteht im dicht besiedelten Rhein-Main-Gebiet eine gute Abnehmerstruktur. Im noerdlichen Oberrheingraben konnte im Mittel ein deutlich erhoehter Temperaturgradient von etwa 60 K/km gegenueber dem kontinentalen Krustendurchschnittswert von 30 K/km nachgewiesen werden. Waemeanomalien wurden lokalisiert. Die Rotliegendschichten weisen im untersuchten Gebiet eindeutig die hoechsten Ressourcen auf. In geringerer Tiefenlage erzielen die Hydrobienschichten noch beachtliche Werte. Nach Norden nimmt das Potential der Schichten ab. Daher ist von einer Nutzung der Hydrogeothermie im noerdlichen Bereich Suedhessens eher abzuraten. Die hoechsten Ressourcen in Suedhessen sind im Bereich von Stockstadt und Biebesheim in den Rotliegenschichten zu erwarten. (orig.)

Cold atoms in singular potentials

International Nuclear Information System (INIS)

Denschlag, J. P.

1998-09-01

We studied both theoretically and experimentally the interaction between cold Li atoms from a magnetic-optical trap (MOT) and a charged or current-carrying wire. With this system, we were able to realize 1/r 2 and 1/r potentials in two dimensions and to observe the motion of cold atoms in both potentials. For an atom in an attractive 1/r 2 potential, there exist no stable trajectories, instead there is a characteristic class of trajectories for which atoms fall into the singularity. We were able to observe this falling of atoms into the center of the potential. Moreover, by probing the singular 1/r 2 potential with atomic clouds of varying size and temperature we extracted scaling properties of the atom-wire interaction. For very cold atoms, and very thin wires the motion of the atoms must be treated quantum mechanically. Here we predict that the absorption cross section for the 1/r 2 potential should exhibit quantum steps. These quantum steps are a manifestation of the quantum mechanical decomposition of plane waves into partial waves. For the second part of this work, we realized a two dimensional 1/r potential for cold atoms. If the potential is attractive, the atoms can be bound and follow Kepler-like orbits around the wire. The motion in the third dimension along the wire is free. We were able to exploit this property and constructed a novel cold atom guide, the 'Kepler guide'. We also demonstrated another type of atom guide (the 'side guide'), by combining the magnetic field of the wire with a homogeneous offset magnetic field. In this case, the atoms are held in a potential 'tube' on the side of the wire. The versatility, simplicity, and scaling properties of this guide make it an interesting technique. (author)

Australia's CO2 geological storage potential and matching of emission sources to potential sinks

International Nuclear Information System (INIS)

Bradshaw, J.; Bradshaw, B.E.; Wilson, P.; Spencer, L.; Allinson, G.; Nguyen, V.

2004-01-01

Within the GEODISC program of the Australian Petroleum Cooperative Research Centre (APCRC), Geoscience Australia (GA) and the University of New South Wales (UNSW) have completed an analysis of the potential for the geological storage of CO 2 . The geological analysis assessed over 100 potential environmentally sustainable sites for CO 2 injection (ESSCIs) by applying a deterministic risk assessment based on the five factors of: storage capacity, injectivity potential, site details, containment and natural resources. Utilising a risked storage capacity suggests that at a regional scale Australia has a CO 2 storage potential in excess of 1600 years of current annual total net emissions. Whilst this estimate does give an idea of the enormous magnitude of the geological storage potential of CO 2 in Australia, it does not account for various factors that are evident in source to sink matching. If preferences due to source to sink matching are incorporated, and an assumption is made that some economic imperative will apply to encourage geological storage of CO 2 , then a more realistic analysis can be derived. In such a case, Australia may have the potential to store a maximum of 25% of our total annual net emissions, or approximately 100-115 Mt CO 2 per year. (author)

Estimation of potential uranium resources

International Nuclear Information System (INIS)

Curry, D.L.

1977-09-01

Potential estimates, like reserves, are limited by the information on hand at the time and are not intended to indicate the ultimate resources. Potential estimates are based on geologic judgement, so their reliability is dependent on the quality and extent of geologic knowledge. Reliability differs for each of the three potential resource classes. It is greatest for probable potential resources because of the greater knowledge base resulting from the advanced stage of exploration and development in established producing districts where most of the resources in this class are located. Reliability is least for speculative potential resources because no significant deposits are known, and favorability is inferred from limited geologic data. Estimates of potential resources are revised as new geologic concepts are postulated, as new types of uranium ore bodies are discovered, and as improved geophysical and geochemical techniques are developed and applied. Advances in technology that permit the exploitation of deep or low-grade deposits, or the processing of ores of previously uneconomic metallurgical types, also will affect the estimates

Lift enhancement by trapped vortex

Science.gov (United States)

Rossow, Vernon J.

1992-01-01

The viewgraphs and discussion of lift enhancement by trapped vortex are provided. Efforts are continuously being made to find simple ways to convert wings of aircraft from an efficient cruise configuration to one that develops the high lift needed during landing and takeoff. The high-lift configurations studied here consist of conventional airfoils with a trapped vortex over the upper surface. The vortex is trapped by one or two vertical fences that serve as barriers to the oncoming stream and as reflection planes for the vortex and the sink that form a separation bubble on top of the airfoil. Since the full three-dimensional unsteady flow problem over the wing of an aircraft is so complicated that it is hard to get an understanding of the principles that govern the vortex trapping process, the analysis is restricted here to the flow field illustrated in the first slide. It is assumed that the flow field between the two end plates approximates a streamwise strip of the flow over a wing. The flow between the endplates and about the airfoil consists of a spanwise vortex located between the suction orifices in the endplates. The spanwise fence or spoiler located near the nose of the airfoil serves to form a separated flow region and a shear layer. The vorticity in the shear layer is concentrated into the vortex by withdrawal of fluid at the suction orifices. As the strength of the vortex increases with time, it eventually dominates the flow in the separated region so that a shear or vertical layer is no longer shed from the tip of the fence. At that point, the vortex strength is fixed and its location is such that all of the velocity contributions at its center sum to zero thereby making it an equilibrium point for the vortex. The results of a theoretical analysis of such an idealized flow field are described.

MRI reporting by radiographers: The construction of an objective structured examination

International Nuclear Information System (INIS)

Piper, K.J.; Buscall, K.L.

2008-01-01

Purpose: The aim was to construct a bank of general magnetic resonance imaging (MRI) investigations where good agreement was demonstrated between three independent radiological reports. The bank was subsequently to be used to assess radiographers' ability to accurately report at the end of an accredited programme; Postgraduate Certificate (PgC) Clinical Reporting (MRI-General Investigations). Method: Eighty-seven examinations (33 knee, 36 lumbar spine and 18 internal auditory meatus-IAM) were initially reported by two radiologists. Seventy-two of these examinations (25 knee, 29 lumbar spine and 18 IAM) were subsequently reported by a third radiologist. Interobserver agreement was assessed by estimating the total, positive and negative % agreement rates; and by use of the weighted or unweighted kappa values. Knee reports were analysed for meniscal tears, and degenerative meniscus (264 meniscal sites); ligament injury (ACL; PCL; MCI; and LCL; 132 ligament sites); bone bruise; effusion; fracture and/or osteochondral defect. Lumbar spine reports were analysed for disc morphology (bulge, protrusion, extrusion and/or annular tear-180 intervertebral disc levels); degenerative disc disease; Modic endplate changes; cord compression; spinal stenosis; nerve root involvement; vertebral collapse, primary tumour or metastases; and other incidental findings. IAM reports were analysed for acoustic neuroma and vascular loop. Results: Agreement in the knee reports varied mainly between moderate (κ = 0.46) for ligament injury to very good [almost perfect] (κ = 0.86) for meniscal tears, although agreement for degenerative meniscus was only fair (κ = 0.3). Variation in the lumbar spine reports ranged predominantly between moderate (κ = 0.54) for disc bulge/protrusion to fair (κ = 0.32) for Modic endplate changes to good [substantial] (κ = 0.79) for tumour/metastases. Agreement for the presence of acoustic neuroma was very good [almost perfect] (κ = 1.0). Forty cases

Type II Modic Changes May not Always Represent Fat Degeneration: A Study Using MR Fat Suppression Sequence.

Science.gov (United States)

Feng, Zhiyun; Liu, Yuanhao; Wei, Wei; Hu, Shengping; Wang, Yue

2016-08-15

A radiological study of type II Modic changes (MCs). The aim of this study was to determine the characteristics of type II MCs on fat suppression (FS) magnetic resonance (MR) images and its association with radiological disc degeneration. Type II MCs are common endplate signal changes on MR images. On the basis of limited histological samples, type II MCs are thought to be stable fat degeneration. FS technique on MR, which can quantify fat content, may be an alternative to explore the pathology of MCs. To date, however, the characteristics of type II MCs on FS sequence have not been studied. Lumbar MR images conducted in a single hospital during a defined period were reviewed to include those with type II MCs and FS images. On FS images, signal status of type II MCs was visually classified as suppressed or not-suppressed. Signal intensity of vertebral regions with and without MCs was measured quantitatively on T2-weighted (T2W) and FS images to calculate fat content index and validate the visual classification. Using image analysis program Osirix, MCs size and adjacent disc degeneration were measured quantitatively. Paired t-tests and logistic regressions were used to determine the associations studied. Sixty-four lumbar MRIs were included and 150 endplates with type II MCs were studied. Although signal of 37 (24.7%) type II MCs was suppressed on FS images, that of 113 (75.3%) was not suppressed. The discs adjacent to type II MCs had lower signal intensity (0.13 ± 0.003 vs. 0.14 ± 0.004, P Type II MCs that were not suppressed on FS image were associated with greater age [odds ratio (OR) = 1.11, P type II MCs was not suppressed on FS MR images, suggesting that there are ongoing complicated pathologies. Type II MCs may not merely represent fat replacement. 3.

Back pain in space and post-flight spine injury: Mechanisms and countermeasure development

Science.gov (United States)

Sayson, Jojo V.; Lotz, Jeffrey; Parazynski, Scott; Hargens, Alan R.

2013-05-01

During spaceflight many astronauts experience moderate to severe lumbar pain and deconditioning of paraspinal muscles. There is also a significant incidence of herniated nucleus pulposus (HNP) in astronauts post-flight being most prevalent in cervical discs. Relief of in-flight lumbar back pain is facilitated by assuming a knee-to-chest position. The pathogenesis of lumbar back pain during spaceflight is most likely discogenic and somatic referred (from the sinuvertebral nerves) due to supra-physiologic swelling of the lumbar intervertebral discs (IVDs) due to removal of gravitational compressive loads in microgravity. The knee-to-chest position may reduce lumbar back pain by redistributing stresses through compressive loading to the IVDs, possibly reducing disc volume by fluid outflow across IVD endplates. IVD stress redistribution may reduce Type IV mechanoreceptor nerve impulse propagation in the annulus fibrosus and vertebral endplate resulting in centrally mediated pain inhibition during spinal flexion. Countermeasures for lumbar back pain may include in-flight use of: (1) an axial compression harness to prevent excessive IVD expansion and spinal column elongation; (2) the use of an adjustable pulley exercise developed to prevent atrophy of spine muscle stabilisers; and (3) other exercises that provide Earth-like annular stress with low-load repetitive active spine rotation movements. The overall objective of these countermeasures is to promote IVD health and to prevent degenerative changes that may lead to HNPs post-flight. In response to "NASA's Critical Path Roadmap Risks and Questions" regarding disc injury and higher incidence of HNPs after space flight (Integrated Research Plan Gap-B4), future studies will incorporate pre- and post-flight imaging of International Space Station long-duration crew members to investigate mechanisms of lumbar back pain as well as degeneration and damage to spinal structures. Quantitative results on morphological, biochemical

Robotics Potential Fields

Directory of Open Access Journals (Sweden)

Jordi Lucero

2009-01-01

Full Text Available This problem was to calculate the path a robot would take to navigate an obstacle field and get to its goal. Three obstacles were given as negative potential fields which the robot avoided, and a goal was given a positive potential field that attracted the robot. The robot decided each step based on its distance, angle, and influence from every object. After each step, the robot recalculated and determined its next step until it reached its goal. The robot's calculations and steps were simulated with Microsoft Excel.

Neutron optical potentials

International Nuclear Information System (INIS)

Wilmore, D.; Hodgson, P.E.

1976-01-01

The purpose of this paper is to provide a guide to the use of optical model computer programs to analyse and calculate neutron data. After a brief discussion of the physical basis of the optical model a survey is given of the most widely used optical model and Hauser-Feshbach computer programs. The range of applicability and reliability of the major optical potentials proposed is assessed by comparison with available experimental data and some observations and suggestions are made for the optimum choice of optical potentials for given purposes of neutron data calculations. (author)

Potential support ratios

DEFF Research Database (Denmark)

Kjærgaard, Søren; Canudas-Romo, Vladimir

2017-01-01

The ‘prospective potential support ratio’ has been proposed by researchers as a measure that accurately quantifies the burden of ageing, by identifying the fraction of a population that has passed a certain measure of longevity, for example, 17 years of life expectancy. Nevertheless......, the prospective potential support ratio usually focuses on the current mortality schedule, or period life expectancy. Instead, in this paper we look at the actual mortality experienced by cohorts in a population, using cohort life tables. We analyse differences between the two perspectives using mortality models...

The logarithmic potential

CERN Document Server

Evans, Griffith Conrad

1927-01-01

This book studies fundamental properties of the logarithmic potential and their connections to the theory of Fourier series, to potential theory, and to function theory. The material centers around a study of Poisson's integral in two dimensions and of the corresponding Stieltjes integral. The results are then extended to the integrals in terms of Green's functions for general regions. There are some thirty exercises scattered throughout the text. These are designed in part to familiarize the reader with the concepts introduced, and in part to complement the theory. The reader should know some

Scalar potentials and the Dirac equation

International Nuclear Information System (INIS)

Bergerhoff, B.; Soff, G.

1994-01-01

The Dirac equation is solved for various types of scalar potentials. Energy eigenvalues and normalized bound-state wave functions are calculated analytically for a scalar 1/r-potential as well as for a mixed scalar and Coulomb 1/r-potential. Also continuum wave functions for positive and negative energies are derived. Similarly, we investigate the solutions of the Dirac equation for a scalar square-well potential. Relativistic wave functions for scalar Yukawa and exponential potentials are determined numerically. Finally, we also discuss solutions of the Dirac equation for scalar linear and quadratic potentials which are frequently used to simulate quark confinement. (orig.)

The nucleon-nucleon potential

International Nuclear Information System (INIS)

Green, A.M.

1978-01-01

The first part of this talk is based on the one presented at the Tokyo conference last September and can be found in ref( 1 ). This coveres such topics as the Paris and Stonybrook potentials, the new values of the NN coupling constants and also our understanding of the NNω coupling constant. The second part reviews recent developments concerning the Paris potential, the application of the MIT bag model to the NN interaction, the effect of crossed pion processes and vertex form factors. Comments made about the possible future trends of NN potential calculations. The current status of the D-state probability of the deuteron is discussed. (orig./AH) [de

Evaluation of the prevention potential against landslide disasters. Jisuberi saigai wo taisho to shita bosai potential no hyoka

Energy Technology Data Exchange (ETDEWEB)

Umemura, J [Nihon University, Tokyo (Japan). College of Engineering; Hayashi, S; Ochiai, H [Kyushu University, Fukuoka (Japan). Faculty of Engineering

1994-03-21

In order to evaluate disaster potential and disaster prevention potential of landslides, which are complicatedly composed of natural factors and social ones, an evaluating method of the potentials is proposed by applying the multiple logistic model. Furthermore, a method making the potential map using this evaluation is shown. The multiple logistic model is based on the conception of multiple risks, and so the disaster potential is expressed with probability. The disaster prevention potential is evaluated by using the disaster potential. Taking a typical landslide district as an instance, some potential maps colored by each potential are shown. By these maps, effects of the preventive measures against disasters and changes in the disaster prevention potential according to the industrial structure as well as the population are evaluated. Furthermore, combination of the other disaster potentials obtained by changing the surveying interval or factors makes it possible to draw various disaster maps and disaster prevention ones for different purposes. 15 refs., 17 figs., 3 tabs.

Constant potential high-voltage generator

International Nuclear Information System (INIS)

Resnick, T.A.; Dupuis, W.A.; Palermo, T.

1980-01-01

An X-ray tube voltage generator with automatic stabilization circuitry is disclosed. The generator includes a source of pulsating direct current voltage such as from a rectified 3 phase transformer. This pulsating voltage is supplied to the cathode and anode of an X-ray tube and forms an accelerating potential for electrons within that tube. The accelerating potential is stabilized with a feedback signal which is provided by a feedback network. The network includes an error signal generator which compares an instantaneous accelerating potential with a preferred reference accelerating potential and generates an error function. This error function is transmitted to a control tube grid which in turn causes the voltage difference between X-ray tube cathode and anode to stabilize and thereby reduce the error function. In this way stabilized accelerating potentials are realized and uniform X-ray energy distributions produced. (Auth.)

Comparison of potentials for polymeric liquids

International Nuclear Information System (INIS)

Jung, Hae Young

2002-01-01

Many theories for polymeric liquids are based on the concepts of cell, hole, free volume of lattice etc. In this theories, van der Waals potential, Lennard-Jones 6-12 potential and their modified potentials are commonly used. In this work, Mie(p,6)potential was applied to the Continuous Lattice Fluid Theory (which extends the discrete lattices of Lattice Fluid Theory to classically continuous lattices) and Dee-Walsch's Cell Theory (which modifies Flory's Equation of State Theory). Both of them are known to be successful theories for polymeric liquids. Thus, PVT values changing with p (the exponent in the repulsion potential) were calculated and compared with experimental values. And, calculated values of Lattice Fluid theory, Flory's Equation of State Theory and Cho-Sanchez Theory using perturbation method were also compared. Through the calculated results, van der Waals potential, Lennard-Jones 6-12 potential and Mie(p,6) potential for polymeric liquids were compared with each other

Quaternionic potentials and CP-violation

International Nuclear Information System (INIS)

Nishi, Celso Chikahiro

2000-01-01

Full text follows: In the formulation of Quantum Mechanics by using a non-commutative ring of quaternions, we attempt to solve the Schroedinger equation with quaternionic potentials. Decay processes can easily be modeled by including complex imaginary potentials. Although, it could be explained as a transition between states under action of a perturbation. Purely imaginary quaternionic potentials can be used to describe CP-violation effects. The neutral kaon system, K 0 - K-bar 0 or K L - K S , represents an example of CP-violation phenomenon. The inclusion of quaternionic potentials imply a reformulation of the whole quantum theory. The use of a quaternionic algebra in discussing the Schroedinger equation leads to the lost of time reversal invariance (T), closely connected to CP violation by the well-known CPT theorem. In particular, we study the Schroedinger equation in presence of a quaternionic potential barrier given in terms of V, real potential acting in the region of width a, and jW, purely quaternionic potential acting in the region of width b. Different cases, |W|/V and b/a, are discussed in view of possible deviations of standard Quantum Mechanics. The complex linear Schroedinger equation is solved for stationary states. The explicit solution contains complex and quaternionic transmission/reflection coefficients. A wave packet treatment needs to make a more realistic and physical description. We briefly discuss possible interpretations and remaining questions. (author)

Assessing offshore wind potential

International Nuclear Information System (INIS)

Adelaja, Adesoji; McKeown, Charles; Calnin, Benjamin; Hailu, Yohannes

2012-01-01

Quantifying wind potential is a pivotal initial step in developing and articulating a state’s policies and strategies for offshore wind industry development. This is particularly important in the Great Lakes States where lessons from other offshore environments are not directly applicable. This paper presents the framework developed for conducting a preliminary assessment of offshore wind potential. Information on lake bathymetry and wind resources were combined in simulating alternative scenarios of technically feasible turbine construction depths and distance concerns by stakeholders. These yielded estimates of developable offshore wind areas and potential power generation. While concerns about the visibility of turbines from shore reduce the power that can be generated, engineering solutions that increase the depths at which turbines can be sited increase such potential power output. This paper discusses the costs associated with technical limitations on depth and the social costs related to public sentiments about distance from the shoreline, as well as the possible tradeoffs. The results point to a very large untapped energy resource in the Michigan’s Great Lakes, large enough to prompt policy action from the state government. - Highlights: ▶ We build a theoretical framework for modeling offshore wind power production. ▶ Illustration of the impact of technology and social limitations on offshore wind energy development. ▶ Geospatial modeling of the offshore wind potential of the Great Lakes.

Attention effects at auditory periphery derived from human scalp potentials: displacement measure of potentials.

Science.gov (United States)

Ikeda, Kazunari; Hayashi, Akiko; Sekiguchi, Takahiro; Era, Shukichi

2006-10-01

It is known in humans that electrophysiological measures such as the auditory brainstem response (ABR) are difficult to identify the attention effect at the auditory periphery, whereas the centrifugal effect has been detected by measuring otoacoustic emissions. This research developed a measure responsive to the shift of human scalp potentials within a brief post-stimulus period (13 ms), that is, displacement percentage, and applied it to an experiment to retrieve the peripheral attention effect. In the present experimental paradigm, tone pips were exposed to the left ear whereas the other ear was masked by white noise. Twelve participants each conducted two conditions of either ignoring or attending to the tone pips. Relative to averaged scalp potentials in the ignoring condition, the shift of the potentials was found within early component range during the attentive condition, and displacement percentage then revealed a significant magnitude difference between the two conditions. These results suggest that, using a measure representing the potential shift itself, the peripheral effect of attention can be detected from human scalp potentials.

Vicious walkers in a potential

International Nuclear Information System (INIS)

Bray, Alan J; Winkler, Karen

2004-01-01

We consider N vicious walkers moving in one dimension in a one-body potential v(x). Using the backward Fokker-Planck equation we derive exact results for the asymptotic form of the survival probability Q(x, t) of vicious walkers initially located at (x 1 , ..., x N ) = x, when v(x) is an arbitrary attractive potential. Explicit results are given for a square-well potential with absorbing or reflecting boundary conditions at the walls, and for a harmonic potential with an absorbing or reflecting boundary at the origin and the walkers starting on the positive half line. By mapping the problem of N vicious walkers in zero potential onto the harmonic potential problem, we rederive the results by Fisher (1984 J. Stat. Phys. 34 667) and Krattenthaler et al (2000 J. Phys. A: Math. Gen. 33 8835) respectively for vicious walkers on an infinite line and on a semi-infinite line with an absorbing wall at the origin. This mapping also gives a new result for vicious walkers on a semi-infinite line with a reflecting boundary at the origin: Q(x,t) ∼ t N(N-1)/2

Labor potential: enhancing its development

Directory of Open Access Journals (Sweden)

O.P. Melnichuk

2016-06-01

Full Text Available This publication presents the views of the author about the need to expand research of labor potential, estimation of quantitative indicators and qualitative characteristics at the individual, regional levels and the state as a whole to develop the mechanisms of its development. The existing methods of labour potential assessment are mainly based on the probable approach taking into account external and internal factors. In the case of assessment of labour potential of a single enterprise for the most suitable for this production method the mechanisms of its development can be worked out. However, for the state under a certain depreciation of the resource, property, financial and other potentials, aggressive manifestations of the crisis phenomena, processes etc. to resolve urgent is the problem of enhancing the development of qualitative characteristics of labor potential at all its levels. In this context it is important to exploit the potential of domestic education and science which now continue to be reformed for the sake of achieving European standards, using the advanced experience of other countries. Every means of legal, financial, managerial, and organizational impact should be used for this.

The Low Energy Antiproton Ring (LEAR) some months before the start of its particle physics programme

CERN Multimedia

1983-01-01

LEAR*)and its enclosure in the PS South Hall in Jan, 1983, 4 months before the start of its particle physics programme. Visible (in red) are the 90 degree bending magnets consisting of 6 blocks each. Separated from the magnets by short straight sections are the quadrupole doublets (blue with read end-plates). The 4 long straight sections house large equipment like septa for injection/ejection, RF-cavities and later (since 1986) electron cooling and an internal target and its associated detector (JETSET experiment). Two small copper tubes spanning across the ring are coaxial lines transmitting the stochastic cooling signals from pickup to kicker. (see also photos 8205747X, 8207133, 8207541X, 8309026) *)see e.g.: H.Koziol and D. Möhl, Phys. Rep. 403-404 (2004), p.271 and references therein

Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material

International Nuclear Information System (INIS)

Wosik, J.; Kranenburg, R.A.; Wolfe, J.C.; Selvamanickam, V.; Salama, K.

1990-04-01

Measurements are reported of the millimeter-wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid-phase process. The measurements were performed by replacing the endplate of a TE(011) cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. For the parallel configuration, the surface resistance at 77 K and 80 GHz is given. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K and the surface resistance is derived at 88 K. The effect of microstructure on surface resistance is discussed. 19 refs

Endoscopic Pubic Symphysectomy for Athletic Osteitis Pubis.

Science.gov (United States)

Matsuda, Dean K; Sehgal, Bantoo; Matsuda, Nicole A

2015-06-01

Osteitis pubis is a common form of athletic pubalgia associated with femoroacetabular impingement. Endoscopic pubic symphysectomy was developed as a less invasive option than open surgical curettage for recalcitrant osteitis pubis. This technical note demonstrates the use of the anterior and suprapubic portals in the supine lithotomy position for endoscopic burr resection of pubic symphyseal fibrocartilage and hyaline endplates. Key steps include use of the suprapubic portal for burr resection of the posteroinferior symphysis and preservation of the posterior and arcuate ligaments. Endoscopic pubic symphysectomy is a minimally invasive bone-conserving surgery that retains stability and may be useful in the treatment of recalcitrant osteitis pubis or osteoarthritis. It nicely complements arthroscopic surgery for femoroacetabular impingement and may find broader application in this group of co-affected athletes.

Seismic Performance of Steel Frames with Semirigid Connections

Directory of Open Access Journals (Sweden)

Iman Faridmehr

2017-01-01

Full Text Available The nonlinear stiffness matrix method was incorporated to investigate the structural performance of steel portal frames with semirigid connections. A portal frame with unstiffened extended end-plate connection was designed to demonstrate the adequacy of the proposed method. Besides, the seismic performance of steel portal frames with semirigid connections was investigated through time history analysis where kinematic hysteresis model was assigned to semirigid connections to account for energy dissipation and unloading stiffness. Based on the results of the study, it was found that generally semirigid connections influenced the force distribution which resulted in the decrease in base shear and lighter frame compared to the rigid one. The results also indicated that there was no direct relationship between maximum displacement at the top and connection stiffness in high-rise frames.

Stereo: cylindrical drift chamber for muon decay experiments at LAMPF

International Nuclear Information System (INIS)

Bolton, R.D.; Carlini, R.D.; Cooper, M.D.; Frank, J.S.; Hart, V.E.; Matis, H.S.; Mischke, R.E.; Sandberg, V.D.; Sennhauser, U.

1983-01-01

A stereo, cylindrical drift chamber has been built for use in a search for rare decay modes of the muon at LAMPF. This chamber (part of the Crystal Box detector) has 728 cells on 8 concentric annuli at alternating angles of 10 0 to 16 0 from the chamber axis and with radii from 105 to 220 mm. The basic cell cross section is (9 x 10) mm 2 and the inter-layer spacing is 4.7 mm. Preliminary results show the single-wire efficiencies to be greater than 99%. Based on results obtained from prototype chambers, we hope to achieve 170-μm resolution (including multiple scattering) when TDC offsets and sense-wire locations found in a careful inspection of the endplates are added to the track-finding algorithm

CANFLEX fuel bundle cross-flow endurance test 2 (test procedure)

Energy Technology Data Exchange (ETDEWEB)

Hong, Sung Deok; Chung, C. H.; Chang, S. K. [Korea Atomic Energy Research Institute, Taejon (Korea)

1999-04-01

This report describes test procedure of cross-flow 2 test for CANFLEX fuel. In October 1996. a cross-flow test was successfully performed in the KAERI Hot Test Loop for four hours at a water flow rate of 31kg/s, temperature of 266 deg C and inlet pressure of 11MPa, but it is requested more extended time periods to determine a realistic operational margin for the CANFLEX bundle during abnormal refuelling operations. The test shall be conducted for twenty two hours under the reactor conditions. After an initial period of ten hours, the test shall be stopped at the intervals of four hours for bundle inspection and inspect the test bundle end-plate to end-cap welds for failure or crack propagation using liquid penetrant examination. 2 refs., 1 fig. (Author)

Theoretical study on optical model potential

International Nuclear Information System (INIS)

Lim Hung Gi.

1984-08-01

The optical model potential of non-local effect on the rounded edge of the potential is derived. On the basis of this potential the functional form of the optical model potential, the energy dependence and relationship of its parameters, and the dependency of the values of the parameters on energy change are shown in this paper. (author)

Effects of water chemistry and potential distribution on electrochemical corrosion potential measurements in 553 K pure water

International Nuclear Information System (INIS)

Ishida, Kazushige; Wada, Yoichi; Tachibana, Masahiko; Ota, Nobuyuki; Aizawa, Motohiro

2013-01-01

The effects of water chemistry distribution on the potential of a reference electrode and of the potential distribution on the measured potential should be known qualitatively to obtain accurate electrochemical corrosion potential (ECP) data in BWRs. First, the effects of oxygen on a platinum reference electrode were studied in 553 K pure water containing dissolved hydrogen (DH) concentration of 26 - 10 5 μg kg -1 (ppb). The platinum electrode worked in the same way as the theoretical hydrogen electrode under the condition that the molar ratio of DH to dissolved oxygen (DO) was more than 10 and that DO was less than 100 ppb. Second, the effects of potential distribution on the measured potential were studied by using the ECP measurement part without platinum deposition on the surfaces connected to another ECP measurement part with platinum deposition on the surfaces in 553 K pure water containing 100 - 130 ppb of DH or 100 - 130 ppb of DH plus 400 ppb of hydrogen peroxide. Measured potentials for each ECP measurement part were in good agreement with literature data for each surface condition. The lead wire connecting point did not affect the measured potential. Potential should be measured at the nearest point from the reference electrode in which case it will be not affected by either the potential distribution or the connection point of the lead wire in pure water. (author)

Molecular potentials and relaxation dynamics

International Nuclear Information System (INIS)

Karo, A.M.

1981-01-01

The use of empirical pseudopotentials, in evaluating interatomic potentials, provides an inexpensive and convenient method for obtaining highly accurate potential curves and permits the modeling of core-valence correlation, and the inclusion of relativistic effects when these are significant. Recent calculations of the X 1 Σ + and a 3 Σ + states of LiH, NaH, KH, RbH, and CsH and the X 2 Σ + states of their anions are discussed. Pseudopotentials, including core polarization terms, have been used to replace the core electrons, and this has been coupled with the development of compact, higly-optimized basis sets for the corresponding one- and two-electron atoms. Comparisons of the neutral potential curves with experiment and other ab initio calculations show good agreement (within 1000 cm -1 over most of the potential curves) with the difference curves being considerably more accurate. In the method of computer molecular dynamics, the force acting on each particle is the resultant of all interactions with other atoms in the neighborhood and is obtained as the derivative of an effective many-body potential. Exploiting the pseudopotential approach, in obtaining the appropriate potentials may be very fruitful in the future. In the molecular dynamics example considered here, the conventional sum-of-pairwise-interatomic-potentials (SPP) approximation is used with the potentials derived either from experimental spectroscopic data or from Hartree-Fock calculations. The problem is the collisional de-excitation of vibrationally excited molecular hydrogen at an Fe surface. The calculations have been carried out for an initial vibrotational state v = 8, J = 1 and a translational temperature corresponding to a gas temperature of 500 0 K. Different angles of approach and different initial random impact points on the surface have been selected. For any given collision with the wall, the molecule may pick up or lose vibrotatonal and translational energy

Meson-exchange N-N potential

International Nuclear Information System (INIS)

Nutt, W.T.

1976-01-01

A meson-theoretic model of the intermediate range nucleon-nucleon potential is presented with emphasis placed on the two-pion exchange contribution. The Bethe-Salpeter equation is reduced, by the Blankenbecler-Sugar technique, to a Lippmann-Schwinger equation, from which an approximate nonlocal, energy-dependent potential is obtained. The nucleon-antinucleon pair contribution, which plagues meson-theoretical two-pion calculations, is suppressed by the complex poles of the one-nucleon Green's function. The importance of the retention of the explicit energy dependence of the potential is demonstrated by calculating the off-shell scattering matrices. The potential is presented in a linearized (in energy) form with the core region adjusted to produce a fit to low energy data

Potential measurements in tandem mirrors

International Nuclear Information System (INIS)

Glowienka, J.C.

1985-11-01

The US mirror program has begun conducting experiments with a thermal barrier tandem mirror configuration. This configuration requires a specific axial potential profile and implies measurements of potential for documentation and optimization of the configuration. This report briefly outlines the motivation for the thermal barrier tandem mirror and then outlines the techniques used to document the potential profile in conventional and thermal barrier tandem mirrors. Examples of typical data sets from the world's major tandem mirror experiments, TMX and TMX-U at Lawrence Livermore National Laboratory (LLNL) and Gamma 10 at Tsukuba University in Japan, and the current interpretation of the data are discussed together with plans for the future improvement of measurements of plasma potential

Potential theory

CERN Document Server

Helms, Lester L

2014-01-01

Potential Theory presents a clear path from calculus to classical potential theory and beyond, with the aim of moving the reader into the area of mathematical research as quickly as possible. The subject matter is developed from first principles using only calculus. Commencing with the inverse square law for gravitational and electromagnetic forces and the divergence theorem, the author develops methods for constructing solutions of Laplace's equation on a region with prescribed values on the boundary of the region. The latter half of the book addresses more advanced material aimed at those with the background of a senior undergraduate or beginning graduate course in real analysis. Starting with solutions of the Dirichlet problem subject to mixed boundary conditions on the simplest of regions, methods of morphing such solutions onto solutions of Poisson's equation on more general regions are developed using diffeomorphisms and the Perron-Wiener-Brelot method, culminating in application to Brownian motion. In ...

Static quark-antiquark potential

International Nuclear Information System (INIS)

Deo, B.B.; Barik, B.K.

1983-01-01

A heavy-quark--antiquark potential is suggested which connects asymptotic freedom and quark confinement in a unified manner by formal methods of field theory using some plausible assumptions. The potential has only one additional adjustable parameter B which is proportional to (M/sub q//m/sub q/), where M/sub q/ and m/sub q/ are the constituent and current quark masses, respectively

Finite-Temperature Higgs Potentials

International Nuclear Information System (INIS)

Dolgopolov, M.V.; Gurskaya, A.V.; Rykova, E.N.

2016-01-01

In the present article we consider the short description of the “Finite-Temperature Higgs Potentials” program for calculating loop integrals at vanishing external momenta and applications for extended Higgs potentials reconstructions. Here we collect the analytic forms of the relevant loop integrals for our work in reconstruction of the effective Higgs potential parameters in extended models (MSSM, NMSSM and etc.)

A computer simulation of a potential derived from the gay-berne potential for lattice model

Directory of Open Access Journals (Sweden)

Habtamu Zewdie

2000-06-01

Full Text Available The lattice model of elongated molecules interacting via a potential derived from the Gay-Berne pair potential is proposed. We made a systematic study of the effect of varying the molecular elongation and intermolecular vector orientation dependence of the pair potential on the thermodynamic as well as the structural properties of liquid crystals. A Monte Carlo simulations of molecules placed at the site of a simple cubic lattice and interacting via the modified Gay-Berne potential with its nearest neighbours is performed. The internal energy, heat capacity, angular pair correlation function and scalar order parameter are obtained. The results are compared against predictions of molecular field theory, experimental results and that of other related simulations wherever possible. It is shown that for more elongated molecules the nematic-isotropic transition becomes stronger first order transition. For a given molecular elongation as the intermolecular vector orientation dependence becomes larger the nematic-isotropic transition becomes a stronger first order transition as measured by the rate of change of the order parameter and the divergence of the heat capacity. Scaling the potential well seems to have dramatic change on the effect of the potential well anisotropy on trends of nematic-isotropic transition temperature and divergence of the heat capacity. It is shown that the behaviour of many nematics can be described by proposed model with the elongation ratio of molecules and potential well anisotropy ranging from 3 to 5.

Comparison of the effect of soft-core potentials and Coulombic potentials on bremsstrahlung during laser matter interaction

Science.gov (United States)

Pandit, Rishi R.; Becker, Valerie R.; Barrington, Kasey; Thurston, Jeremy; Ramunno, Lora; Ackad, Edward

2018-04-01

An intense, short laser pulse incident on rare-gas clusters can produce nano-plasmas containing energetic electrons. As these electrons undergo scattering, from both phonons and ions, they emit bremsstrahlung radiation. Here, we compare a theory of bremsstrahlung emission appropriate for the interaction of intense lasers with matter using soft-core potentials and Coulombic potentials. A new scaling for the radiation cross-section and the radiated power via bremsstrahlung is derived for a soft-core potential (which depends on the potential depth) and compared with the Coulomb potential. Calculations using the new scaling are performed for electrons in vacuum ultraviolet, infrared and mid-infrared laser pulses. The radiation cross-section and the radiation power via bremsstrahlung are found to increase rapidly with increases in the potential depth of up to around 200 eV and then become mostly saturated for larger depths while remaining constant for the Coulomb potential. In both cases, the radiation cross-section and the radiation power of bremsstrahlung decrease with increases in the laser wavelength. The ratio of the scattering amplitude for the soft-core potential and that for the Coulombic potential decreases exponentially with an increase in momentum transfer. The bremsstrahlung emission by electrons in plasmas may provide a broadband light source for diagnostics.

The neutron optical model potential

International Nuclear Information System (INIS)

Hodgson, P.E.

1989-01-01

The present status of optical model calculations of neutron scattering and interactions is reviewed, with special emphasis on more recent developments and the more promising lines of research. The use of dispersion relations to provide an extra constraint on the potential is discussed, together with their application to studies of the Fermi surface anomaly. The application of potential inversion techniques to determine the form of the potential is also considered. (author). 39 refs, figs

Oxygen potentials of transuranium oxides

International Nuclear Information System (INIS)

Haruyoshi Otobe; Mituso Akabori; Arai Yasuo; Kazuo Minato

2008-01-01

The oxygen potentials of pyrochlore-type Pu 2 Zr 2 O 7+y , fluorite-type (Pu 0.5 Zr 0.5 )O 2-x and AmO 2-x have been measured by the electromotive force (EMF) method with a zirconia solid-electrolyte. The oxygen potentials of these oxides were reviewed. The phase relations, microstructure, equilibrium state of these oxides were discussed, referring to the isothermal curve of the oxygen potentials. (authors)

Remote RemoteRemoteRemote sensing potential for sensing ...

African Journals Online (AJOL)

Remote RemoteRemoteRemote sensing potential for sensing potential for sensing potential for sensing potential for sensing potential for sensing potential for sensing potential for sensing potential for sensing potential for sensing potential for sensing p. A Ngie, F Ahmed, K Abutaleb ...

A semiclassical study of optical potentials - potential resonances -

International Nuclear Information System (INIS)

Lee, S.Y.; Takigawa, N.; Marty, C.

1977-01-01

A semiclassical method is used to analyze resonances produced by complex potentials. The absorption plays a central role: when it is not too great, resonances manifest themselves by enhancement of cross sections near π. The reverse is not necessarily true, for instance the anomalous large angle scattering for α-Ca is due to a coherent superposition of many partial waves

A parabolic model for dimple potentials

International Nuclear Information System (INIS)

Aydin, Melike Cibik; Uncu, Haydar; Deniz, Coskun

2013-01-01

We study the truncated parabolic function and demonstrate that it is a representation of the Dirac δ function. We also show that the truncated parabolic function, used as a potential in the Schrödinger equation, has the same bound state spectrum, tunneling and reflection amplitudes as the Dirac δ potential, as the width of the parabola approximates to zero. Dirac δ potential is used to model dimple potentials which are utilized to increase the phase-space density of a Bose–Einstein condensate in a harmonic trap. We show that a harmonic trap with a δ function at the origin is a limiting case of the harmonic trap with a symmetric truncated parabolic potential around the origin. Hence, the truncated parabolic is a better candidate for modeling the dimple potentials. (paper)

Supersymmetrically transformed periodic potentials

OpenAIRE

C, David J. Fernandez

2003-01-01

The higher order supersymmetric partners of a stationary periodic potential are studied. The transformation functions associated to the band edges do not change the spectral structure. However, when the transformation is implemented for factorization energies inside of the forbidden bands, the final potential will have again the initial band structure but it can have bound states encrusted into the gaps, giving place to localized periodicity defects.

Streaming potential measurements of biosurfaces

Science.gov (United States)

Van Wagenen, R. A.; Andrade, J. D.; Hibbs, J. B., Jr.

1976-01-01

A technique based on the measurement of streaming potentials has been developed to evaluate the electrokinetic region of the cell periphery. This approach is feasible for cell lines propagated in in-vitro cell cultures in monolayer form. The advantage of this system is that cells may be evaluated in the living state atttached to a substrate; it is not necessary to subject the cells to enzymatic, chemical, or mechanical trauma required to obtain monodisperse suspensions which are then normally evaluated by microelectrophoresis. In this manner, it should be possible to study the influence of substrate and environmental factors on the charge density and potential at the cell periphery. The apparatus and procedure are described as well as some results concerning the electrokinetic potential of borosilicate capillaries as a function of ionic strength, pH, and temperature. The effect that turbulence and entrance flow conditions have on accurate streaming-potential measurements is discussed. The electrokinetic potential of BALB/c 3T12 fibroblasts has been quantified as a function of pH, ionic strength, glutaraldehyde fixation, and Giemsa staining.

Economic potential of inertial fusion

International Nuclear Information System (INIS)

Nuckolls, J.H.

1984-04-01

Beyond the achievement of scientific feasibility, the key question for fusion energy is: does it have the economic potential to be significantly cheaper than fission and coal energy. If fusion has this high economic potential then there are compelling commercial and geopolitical incentives to accelerate the pace of the fusion program in the near term, and to install a global fusion energy system in the long term. Without this high economic potential, fusion's success depends on the failure of all alternatives, and there is no real incentive to accelerate the program. If my conjectures on the economic potential of inertial fusion are approximately correct, then inertial fusion energy's ultimate costs may be only half to two-thirds those of advanced fission and coal energy systems. Relative cost escalation is not assumed and could increase this advantage. Both magnetic and inertial approaches to fusion potentially have a two-fold economic advantage which derives from two fundamental properties: negligible fuel costs and high quality energy which makes possible more efficient generation of electricity. The wining approach to fusion may excel in three areas: electrical generating efficiency, minimum material costs, and adaptability to manufacture in automated factories. The winning approach must also rate highly in environmental potential, safety, availability factor, lifetime, small 0 and M costs, and no possibility of utility-disabling accidents

Iterated interactions method. Realistic NN potential

International Nuclear Information System (INIS)

Gorbatov, A.M.; Skopich, V.L.; Kolganova, E.A.

1991-01-01

The method of iterated potential is tested in the case of realistic fermionic systems. As a base for comparison calculations of the 16 O system (using various versions of realistic NN potentials) by means of the angular potential-function method as well as operators of pairing correlation were used. The convergence of genealogical series is studied for the central Malfliet-Tjon potential. In addition the mathematical technique of microscopical calculations is improved: new equations for correlators in odd states are suggested and the technique of leading terms was applied for the first time to calculations of heavy p-shell nuclei in the basis of angular potential functions

Orbital correlation effects. II. Potential curve and ionization potential of boron hydride

International Nuclear Information System (INIS)

Mehler, E.L.; Van der Vele, G.A.; Nieuwpoort, W.C.

1975-01-01

With the help of the independent pair-potential approximation (IPPA) the valence-shell correlation effects in BH have been calculated at nine internuclear separations. The results are compared with several other methods, including the coupled electron pair approximation (CEPA) and a full configuration interaction expansion. The stability of the IPPA against a unitary transformation of the occupied orbitals has also been investigated, and it is shown that the IPPA is nearly invariant against such transformations. The Dunham procedure has been applied to the results, and the spectroscopic constants obtained from the various approximations are compared. It is furthermore demonstrated that many of the defects present in the Hartree--Fock part of the potential curve and arising from the use of medium-quality basis sets can be eliminated by combining the correlation results with Hartree--Fock results from good-quality basis sets and reapplying the Dunham procedure. Finally the IPPA has been applied to BH + , and the first vertical ionization potential of BH was determined

Anodal sensory nerve action potentials: From physiological understanding to potential clinical applicability.

Science.gov (United States)

Leote, Joao; Pereira, Pedro; Cabib, Christopher; Cipullo, Federica; Valls-Sole, Josep

2016-06-01

Low-intensity electrical stimuli of digital nerves may generate a double peak potential (DPp), composed of a cathodal (caAP) and an anodal (anAP) potential in orthodromic recordings. We studied the effects on caAP and anAP of stimuli of variable intensity, duration, and frequency. We also applied a conditioning stimulus to study potential differences in recovery time. The anAP was obtained in 33 of 40 healthy subjects (82.5%) and 4 of 20 patients with various types of sensory neuropathies (20%). Changes in stimulus duration and intensity had reciprocal effects on the amplitude of the anAP and the caAP. There were significant differences in recovery time between caAP and anAP after a conditioning stimulus. The caAP and anAP are 2 interdependent waveforms generated by different effects of the same stimulus over axons at the verge of depolarization. Muscle Nerve 53: 897-905, 2016. © 2015 Wiley Periodicals, Inc.

Dynamic polarization potentials in heavy ion scattering

International Nuclear Information System (INIS)

Wolf, R.

1984-01-01

In this thesis the polarization potential is calculated which is caused by several collective, strongly coupled states. In the framework of the considered model space the calculation of the polarization potential was exact, i.e. no approximations were made. For this purpose the Green function of the system had to be calculated. This led to a nonlocal polarization potential. For the better interpretation possibility and for the easier use in coupled-channel or optical-model calculations from the nonlocal potentials also equivalent potentials were constructed. The properties of the local and nonlocal potentials as shape, angular momentum, and energy dependence were discussed. Furthermore parametrizations were given, how polarization effects can be regarded in a simple way in optical-model or coupled-channel calculations. The calculations were performed for the systems 12 C+ 12 C and 16 O+ 16 O. To meet as realistic results as possible, parameters for the unperturbed potential were looked for which describe as many data as possible, like angular distributions, excitation functions, and alignment of the main channels. As unperturbed potential both folding potentials and phenomenological potentials were applied in order to study the differences in the polarization potential in the application of deep and flat potentials. (orig./HSI) [de

Low-energy neutron-proton analyzing power and the new Bonn potential and Paris potential predictions

International Nuclear Information System (INIS)

Tornow, W.; Howell, C.R.; Roberts, M.L.; Felsher, P.D.; Chen, Z.M.; Walter, R.L.; Mertens, G.; Slaus, I.

1988-01-01

Instrumental asymmetries recently observed by Haeberli and co-workers, limit the accuracy of neutron-proton analyzing power A/sub y/(θ) data. These instrumental effects are discussed and calculated for previously published n-p A/sub y/(θ) data at 16.9 MeV. To enable these calculations, the analyzing power for the 2 H(d-arrow-right,n) 3 He reaction was measured at small angles. Additional n-p A/sub y/(θ) data at extreme backward angles, obtained via proton recoil detection, are also reported for this energy in this paper. The composite data set is compared to calculations based on the new Bonn NN potential, the Paris NN potential, and to the recent NN phase-shift solution of Arndt. In addition, a detailed comparison between A/sub y/(θ) calculated from the new Bonn and the Paris potentials between 10 and 50 MeV is shown to reveal unexpectedly large relative differences. The experimental data in this energy range are better described by the Paris potential than by the new Bonn potential

Deforming tachyon kinks and tachyon potentials

International Nuclear Information System (INIS)

Afonso, Victor I.; Bazeia, Dionisio; Brito, Francisco A.

2006-01-01

In this paper we investigate deformation of tachyon potentials and tachyon kink solutions. We consider the deformation of a DBI type action with gauge and tachyon fields living on D1-brane and D3-brane world-volume. We deform tachyon potentials to get other consistent tachyon potentials by using properly a deformation function depending on the gauge field components. Resolutions of singular tachyon kinks via deformation and applications of deformed tachyon potentials to scalar cosmology scenario are discussed

Construction of high-quality NN potential models

International Nuclear Information System (INIS)

Stoks, V.G.J.; Klomp, R.A.M.; Terheggen, C.P.F.; de Swart, J.J.

1994-01-01

We present an updated version (Nijm93) of the Nijmegen soft-core potential, which gives a much better description of the np data than the older version (Nijm78). The χ 2 per datum is 1.87. The configuration-space and momentum-space versions of this potential are exactly equivalent, a unique feature among meson-theoretical potentials. We also present three new NN potential models: a nonlocal Reid-like Nijmegen potential (Nijm I), a local version (Nijm II), and an updated regularized version (Reid 93) of the Reid soft-core potential. These three potentials all have a nearly optimal χ 2 per datum and can therefore be considered as alternative partial-wave analyses. All potentials contain the proper charge-dependent one-pion-exchange tail

Enterprise Potential: Essence, Classification and Types

Directory of Open Access Journals (Sweden)

Turylo Anatolii M.

2014-02-01

Full Text Available The article considers existing approaches to classification of the enterprise potential as an economic notion. It offers own vision of classification of enterprise potential, which meets modern tendencies of enterprise development. Classification ensures a possibility of a wider description and assessment of enterprise potential and also allows identification of its most significant characteristics. Classification of the enterprise potential is developed by different criteria: by functions, by resource support, by ability to adapt, by the level of detection, by the spectrum of taking into account possibilities, by the period of coverage of possibilities and by the level of use. Analysis of components of the enterprise potential allows obtaining a complete and trustworthy assessment of the state of an enterprise. Adaptation potential of an enterprise is based on principles systemacy and dynamism, it characterises possibilities of adjustment of an enterprise to external and internal economic conditions.

Indoor radon risk potential of Hawaii

International Nuclear Information System (INIS)

Reimer, G.M.; Szarzi, S.L.

2005-01-01

A comprehensive evaluation of radon risk potential in the State of Hawaii indicates that the potential for Hawaii is low. Using a combination of factors including geology, soils, source-rock type, soil-gas radon concentrations, and indoor measurements throughout the state, a general model was developed that permits prediction for various regions in Hawaii. For the nearly 3,100 counties in the coterminous U.S., National Uranium Resource Evaluation (NURE) aerorad data was the primary input factor. However, NURE aerorad data was not collected in Hawaii, therefore, this study used geology and soil type as the primary and secondary components of potential prediction. Although the radon potential of some Hawaiian soils suggests moderate risk, most houses are built above ground level and the radon soil potential is effectively decoupled from the house. Only underground facilities or those with closed or recirculating ventilation systems might have elevated radon potential. (author)

Potential Theory Surveys and Problems

CERN Document Server

Lukeš, Jaroslav; Netuka, Ivan; Veselý, Jiří

1988-01-01

The volume comprises eleven survey papers based on survey lectures delivered at the Conference in Prague in July 1987, which covered various facets of potential theory, including its applications in other areas. The survey papers deal with both classical and abstract potential theory and its relations to partial differential equations, stochastic processes and other branches such as numerical analysis and topology. A collection of problems from potential theory, compiled on the occasion of the conference, is included, with additional commentaries, in the second part of this volume.

Chemical potentials in gauge theories

International Nuclear Information System (INIS)

Actor, A.; Pennsylvania State Univ., Fogelsville

1985-01-01

One-loop calculations of the thermodynamic potential Ω are presented for temperature gauge and non-gauge theories. Prototypical formulae are derived which give Ω as a function of both (i) boson and/or fermion chemical potential, and in the case of gauge theories (ii) the thermal vacuum parameter Asub(O)=const (Asub(μ) is the euclidean gauge potential). From these basic abelian gauge theory formulae, the one-loop contribution to Ω can readily be constructed for Yang-Mills theories, and also for non-gauge theories. (orig.)

The deuteron microscopic optical potential

International Nuclear Information System (INIS)

Lu Congshan; Zhang Jingshang; Shen Qingbiao

1991-01-01

The two particle Green's function is introduced. When the direct interaction between two nucleons is neglected, the first and second order mass operators of two particles are the sum of those for each particle. The nucleon microscopic optical potential is calculated by applying nuclear matter approximation and effective Skyrme interaction. Then the deuteron microscopic optical potential (DMOP) is calculated by using fold formula. For improvement of the theory, the two particle polarization diagram contribution to the imaginary part of the deuteron microscopic optical potential is studied

ASYMPT - a program to calculate asymptotics of hyperspherical potential curves and adiabatic potentials

International Nuclear Information System (INIS)

Abrashkevich, A.G.; Puzynin, I.V.; Vinitskij, S.I.

1997-01-01

A FORTRAN 77 program is presented which calculates asymptotics of potential curves and adiabatic potentials with an accuracy of O(ρ -2 ) in the framework of the hyperspherical adiabatic (HSA) approach. It is shown that matrix elements of the equivalent operator corresponding to the perturbation ρ -2 have a simple form in the basis of the Coulomb parabolic functions in the body-fixed frame and can be easily computed for high values of total orbital momentum and threshold number. The second-order corrections to the adiabatic curves are obtained as the solutions of the corresponding secular equation. The asymptotic potentials obtained can be used for the calculation of the energy levels and radial wave functions of two-electron systems in the adiabatic and coupled-channel approximations of the HSA approach

Simple exercises to flatten your potential

Energy Technology Data Exchange (ETDEWEB)

Dong, Xi; Horn, Bart; Silverstein, Eva [Stanford Univ., Stanford, CA (United States). SLAC and Dept. of Physics; California Univ., Santa Barbara, CA (United States). Kavli Inst. for Theoretical Physics; Westphal, Alexander [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stanford Univ., Stanford, CA (United States). SLAC and Dept. of Physics

2010-11-15

We show how backreaction of the inflation potential energy on heavy scalar fields can flatten the inflationary potential, as the heavy fields adjust to their most energetically favorable configuration. This mechanism operates in previous UV-complete examples of axion monodromy inflation - flattening a would-be quadratic potential to one linear in the inflaton field - but occurs more generally, and we illustrate the effect with several examples. Special choices of compactification minimizing backreaction may realize chaotic inflation with a quadratic potential, but we argue that a flatter potential such as power-law inflation V({phi}){proportional_to} {phi}{sup p} with p<2 is a more generic option at sufficiently large values of {phi}. (orig.)

Simple exercises to flatten your potential

International Nuclear Information System (INIS)

Dong, Xi; Horn, Bart; Silverstein, Eva; California Univ., Santa Barbara, CA; Westphal, Alexander; Stanford Univ., Stanford, CA

2010-11-01

We show how backreaction of the inflation potential energy on heavy scalar fields can flatten the inflationary potential, as the heavy fields adjust to their most energetically favorable configuration. This mechanism operates in previous UV-complete examples of axion monodromy inflation - flattening a would-be quadratic potential to one linear in the inflaton field - but occurs more generally, and we illustrate the effect with several examples. Special choices of compactification minimizing backreaction may realize chaotic inflation with a quadratic potential, but we argue that a flatter potential such as power-law inflation V(φ)∝ φ p with p<2 is a more generic option at sufficiently large values of φ. (orig.)

Potential controlled flotation of Sarcheshmeh Molybdenite

International Nuclear Information System (INIS)

Kolahdoozan, M.; Noori, H.

2007-01-01

Molybdenite flotation in the Sarcheshmeh Copper Complex was studied as a function of pulp potential, controlled using two types of sodium sulfide, a mineral origin and a chemical nature. Air and either plant or laboratory nitrogen were used as flotation careers. Potential readings took place in rougher cells, as it was proved to be vital in the molybdenite circuit. Results showed that, at reducing potentials between -525 and -575 mv, the highest molybdenum recovery of 93% and the lowest copper recovery of 4-15% can be achieved. These potentials did not change considerably by adding extra amounts of sodium sulfide. At more oxidizing potentials, i.e. more than -450 mv, copper recovery increases while the recovery of Molybdenite drops

Nonresonant approximations to the optical potential

International Nuclear Information System (INIS)

Kowalski, K.L.

1982-01-01

A new class of approximations to the optical potential, which includes those of the multiple-scattering variety, is investigated. These approximations are constructed so that the optical potential maintains the correct unitarity properties along with a proper treatment of nucleon identity. The special case of nucleon-nucleus scattering with complete inclusion of Pauli effects is studied in detail. The treatment is such that the optical potential receives contributions only from subsystems embedded in their own physically correct antisymmetrized subspaces. It is found that a systematic development of even the lowest-order approximations requires the use of the off-shell extension due to Alt, Grassberger, and Sandhas along with a consistent set of dynamical equations for the optical potential. In nucleon-nucleus scattering a lowest-order optical potential is obtained as part of a systematic, exact, inclusive connectivity expansion which is expected to be useful at moderately high energies. This lowest-order potential consists of an energy-shifted (trho)-type term with three-body kinematics plus a heavy-particle exchange or pickup term. The natural appearance of the exchange term additivity in the optical potential clarifies the role of the elastic distortion in connection with the treatment of these processes. The relationship of the relevant aspects of the present analysis of the optical potential to conventional multiple scattering methods is discussed

The electromagnetic potentials without the gauge transformations

Energy Technology Data Exchange (ETDEWEB)

Espinoza, Augusto; Chubykalo, Andrey; Rodriguez, Alejandro Gutierrez; Hernandez, Maria de los Angeles [Universidad Autonoma de Zacatecas (Mexico). Unidad Academica de Fisica

2011-07-01

In this note we show that the use of the Helmholtz theorem lead to derivation of uniquely determined electromagnetic potentials without making use of the gauge transformation. These potentials correspond to the potentials obtained by imposing so-called Coulomb condition (gauge) in the traditional approach. We show that the electromagnetic field comprises two components, one of which is characterized by its instantaneous action at a distance, whereas another one propagates in the retarded form with the velocity of light. One of the theoretical consequences of this new definition is that the electromagnetic potentials are real physical quantities as well as the electric and magnetic fields. We show that the reality of the electromagnetic potentials in quantum-mechanics is also a property of these potentials in the classical electrodynamics. Equations for potentials obtained in our approach are already separated with respect to vector and scalar potentials, so there is no necessity in using the gauge transformations and, accordingly, in making use of either Lorentz or Coulomb condition. The vector potential and scalar potential introduced thus are uniquely defined. The scalar potential is a generator of the so called instantaneous action at a distance, whereas the solenoidal vector potential can propagate with the velocity of light and it is responsible for the retarded action of the electromagnetic field. (author)

Potentials and limitations of hazard indices for the determination of risk potentials of disposed toxic wastes

International Nuclear Information System (INIS)

Kirchner, Gerald

1989-01-01

Hazard indices are often used for the determination of risk potentials arising from the geological disposal of toxic wastes. They are based on simplified models for the calculation of potential health effects caused by the wastes. The attractiveness of hazard indices lies in their simplicity which nevertheless results in reliable data on necessary isolation times and the most toxic nuclides of a waste. They also make possible comparisons of the potential risks of different wastes. After a discussion of the processes that control the behavior of toxic wastes in the environment after a failure of the geological barriers, a new hazard index is presented. Originally developed for nuclear wastes, it is the first which involves the joint consideration of the composition of a waste, the probability for transport of waste nuclides to man, their toxicity, and the time-dependent changes of the risk potentials which are caused by radioactive buildup and decay processes after the waste has entered the biosphere. The new hazard index makes possible the calculation of risk potentials at a given time of release and time period of concern thereafter. Sample calculations for different nuclear wastes show the importance of the model improvements on resulting time-dependent risk potentials. Applicability of the new hazard index to non-nuclear wastes is described. Potentials and limitations of comparative risk assessments using hazard indices are discussed. (author)

Atmospheric chemistry of short-chain haloolefins: photochemical ozone creation potentials (POCPs), global warming potentials (GWPs), and ozone depletion potentials (ODPs).

Science.gov (United States)

Wallington, T J; Sulbaek Andersen, M P; Nielsen, O J

2015-06-01

Short-chain haloolefins are being introduced as replacements for saturated halocarbons. The unifying chemical feature of haloolefins is the presence of a CC double bond which causes the atmospheric lifetimes to be significantly shorter than for the analogous saturated compounds. We discuss the atmospheric lifetimes, photochemical ozone creation potentials (POCPs), global warming potentials (GWPs), and ozone depletion potentials (ODPs) of haloolefins. The commercially relevant short-chain haloolefins CF3CFCH2 (1234yf), trans-CF3CHCHF (1234ze(Z)), CF3CFCF2 (1216), cis-CF3CHCHCl (1233zd(Z)), and trans-CF3CHCHCl (1233zd(E)) have short atmospheric lifetimes (days to weeks), negligible POCPs, negligible GWPs, and ODPs which do not differ materially from zero. In the concentrations expected in the environment their atmospheric degradation products will have a negligible impact on ecosystems. CF3CFCH2 (1234yf), trans-CF3CHCHF (1234ze(Z)), CF3CFCF2 (1216), cis-CF3CHCHCl (1233zd(Z)), and trans-CF3CHCHCl (1233zd(E)) are environmentally acceptable. Copyright © 2015 Elsevier Ltd. All rights reserved.

Square well approximation to the optical potential

International Nuclear Information System (INIS)

Jain, A.K.; Gupta, M.C.; Marwadi, P.R.

1976-01-01

Approximations for obtaining T-matrix elements for a sum of several potentials in terms of T-matrices for individual potentials are studied. Based on model calculations for S-wave for a sum of two separable non-local potentials of Yukawa type form factors and a sum of two delta function potentials, it is shown that the T-matrix for a sum of several potentials can be approximated satisfactorily over all the energy regions by the sum of T-matrices for individual potentials. Based on this, an approximate method for finding T-matrix for any local potential by approximating it by a sum of suitable number of square wells is presented. This provides an interesting way to calculate the T-matrix for any arbitary potential in terms of Bessel functions to a good degree of accuracy. The method is applied to the Saxon-Wood potentials and good agreement with exact results is found. (author)

Exceptional circles of radial potentials

International Nuclear Information System (INIS)

Music, M; Perry, P; Siltanen, S

2013-01-01

A nonlinear scattering transform is studied for the two-dimensional Schrödinger equation at zero energy with a radial potential. Explicit examples are presented, both theoretically and computationally, of potentials with nontrivial singularities in the scattering transform. The singularities arise from non-uniqueness of the complex geometric optics solutions that define the scattering transform. The values of the complex spectral parameter at which the singularities appear are called exceptional points. The singularity formation is closely related to the fact that potentials of conductivity type are ‘critical’ in the sense of Murata. (paper)

The Anthropology of Potentiality in Biomedicine

DEFF Research Database (Denmark)

Taussig, Karen-Sue; Hoeyer, Klaus; Helmreich, Stefan

2013-01-01

with potential. We suggest that anthropologists of the life sciences and biomedicine should work reflexively with the concept of potentiality and the politics of its naming and framing. We lay out a set of propositions and emphasize the moral aspects of claims about potentiality as well as the productivity...

The Maritime Potential of ASEAN Economies

Directory of Open Access Journals (Sweden)

Hans-Dieter Evers

2011-01-01

Full Text Available Countries may utilize a long coastline in relation to their landmass as a resource to develop their maritime economy. This paper argues that ASEAN countries differ in utilizing their maritime potential. As a basis for further comparative studies the Center for Policy Research and International Studies (CenPRIS in Penang developed a set of indicators to measure the maritime potential of nations, the state of their maritime industries, and the degree to which the maritime potential has actually been utilized. Using the CenPRIS Ocean Index (COI shows that Brunei and the Philippines have underutilized their maritime potentials, whereas Singapore and Thailand have made full use of it. Malaysia still has the potential to further develop its maritime economy.

The erosive potential of lollipops

NARCIS (Netherlands)

Brand, H.S.; Gambon, D.L.; Paap, A.; Bulthuis, M.S.; Veerman, E.C.I.; Nieuw Amerongen, A.V.

2009-01-01

Aim: To determine the erosive potential of several commercially available lollipops and the protective effect of saliva. Methods: The erosive potential of lollipops was determined in vitro by measuring the pH and neutralisable acidity. Subsequently, 10 healthy volunteers tested different types of

Molecular potentials and relaxation dynamics

International Nuclear Information System (INIS)

Karo, A.M.

1981-01-01

The use of empirical pseudopotentials, in evaluating interatomic potentials, provides an inexpensive and convenient method for obtaining highly accurate potential curves and permits the modeling of core-valence correlation, and the inclusion of relativistic effects when these are significant. As an example, recent calculations of the chi 1 Σ + and a 3 Σ + states of LiH, NaH, KH, RbH, and CsH and the chi 2 Σ + states of their anions are discussed. Pseudopotentials, including core polarization terms, have been used to replace the core electrons, and this has been coupled with the development of compact, highly-optimized basis sets for the corresponding one- and two-electron atoms. Comparisons of the neutral potential curves with experiment and other ab initio calculations show good agreement (within 1000 cm -1 over most of the potential curves) with the difference curves being considerably more accurate

Effective potentials for twisted fields

International Nuclear Information System (INIS)

Banach, R.

1981-01-01

Minus the density of the effective action, evaluated at the lowest eigenfunction of the (space-time) derivative part of the second (functional) derivative of the classical action, is proposed as a generalised definition of the effective potential, applicable to twisted as well as untwisted sectors of a field theory. The proposal is corroborated by several specific calculations in the twisted sector, namely phi 4 theory (real and complex) and wrong-sign-Gordon theory, in an Einstein cylinder, where the exact integrability of the static solutions confirms the effective potential predictions. Both models exhibit a phase transition, which the effective potential locates, and the one-loop quantum shift in the critical radius is computed for the real phi 4 model, being a universal result. Topological mass generation at the classical level is pointed out, and the exactness of the classical effective potential approximation for complex phi 4 is discussed. (author)

Resonant coupling between ion bounce in a potential well and the potential relaxation instability

International Nuclear Information System (INIS)

Popa, G.; Schrittwieser, R.

1994-01-01

When in a double plasma machine (DP-machine) plasma is produced solely in the source chamber, not only ions but also electrons can leak through the separating grid into the target chamber, so that a low-density plasma forms there. The electrons are trapped by the traveling ion space charge and can thereby overcome the strongly negative grid bias. The investigations presented here show that a positive space-charge forms behind the grid in the target chamber and a deep potential well is formed around the grid. When the anode of the target chamber is biased positively, under certain conditions a low-frequency instability is observed in the target chamber, the properties of which indicate a potential relaxation oscillation, somewhat similar to the potential relaxation instability in a quiescent plasma machine (Q machine). The frequency of the instability is determined by the ion transit time through a thin layer of the target chamber plasma. In addition, resonant coupling occurs between this frequency and the bounce frequency of ions in the potential well around the grid

Critical potentials, leptons, and weak currents

International Nuclear Information System (INIS)

Smith, P.F.; Lewin, J.D.

1977-12-01

A theoretical study is made of the interaction of very strong localised electromagnetic potentials with charged leptons, and with the vacuum state. The principal objective is to investigate the phenomena which occur when the potential reaches or exceeds the critical value at which bound levels are drawn into the lower continuum. The behaviour of bound and continuum solutions of the Dirac equation for the specific model of a short range potential well in an arbitrarily large bounded volume is examined in detail. Vacuum polarisation effects are computed by summation over the infinite set of single particle levels, and special attention is given to the behaviour of the overall charge distribution as the potential strength increases through the critical value. The most significant features of the results are (a) the formation of highly localised electron or muon bound states, (b) similar critical potential strengths for electrons and muons, and (c) redefinition of the vacuum by one charge unit at the critical potential. These features are analogous to some properties of leptonic and hadronic weak currents, and the hypothesis is proposed that strong short range potentials may provide a possible mediating mechanism for the weak interaction and also a lepton confinement mechanism within the structure of hadrons. (author)

Supermodular Games and Potential Games

NARCIS (Netherlands)

Brânzei, R.; Mallozzi, L.; Tijs, S.H.

2001-01-01

Potential games and supermodular games are attractive games, especially because under certain conditions they possess pure Nash equilibria. Subclasses of games with a potential are considered which are also strategically equivalent to supermodular games. The focus is on two-person zero-sum games and

Potential Theory of Multicomponent Adsorption

DEFF Research Database (Denmark)

Shapiro, Alexander; Stenby, Erling Halfdan

1998-01-01

We developed a theory of multicomponent adsorption on the basis of the potential concept originally suggested by Polanyi. The mixture is considered as a heterogeneous substance segregated in the external field emitted by the adsorbent. The same standard equation of state, with no additional fitting...... and high degree of predictability of the theory developed....... the potential theory and the spreading pressure concept is established, and problems of the theory consistency are studied. Numerical algorithms are suggested for evaluation of the segregated state of the mixture in the potential field of adsorption forces. Comparison with experimental data shows good agreement...

China's Military Potential

National Research Council Canada - National Science Library

Wortzel, Larry

1998-01-01

The People's Republic of China (PRC) is seen by many as an economic powerhouse with the world's largest standing military that has the potential to translate economic power into the military sphere...

Bound-state Dirac eigenvalues for scalar potentials

International Nuclear Information System (INIS)

Ram, B.; Arafah, M.

1981-01-01

The Dirac equation is solved with a linear and a quadratic scalar potential using an approach in which the Dirac equation is first transformed to a one-dimensional Schroedinger equation with an effective potential. The WKB method is used to obtain the energy eigenvalues. The eigenvalues for the quadratic scalar potential are real just as they are for the linear potential. The results with the linear potential agree well with those obtained by Critchfield. (author)

Some torsion potentials

Energy Technology Data Exchange (ETDEWEB)

Grundberg, J; Lindstrom, U

1986-10-01

Using the notion of torsion potentials, the duality between antisymmetric tensor fields and scalar fields is discussed. First-order actions with these fields, the connection and the metric as independent variables are presented.

Ambipolar potential formation in TMX

International Nuclear Information System (INIS)

Correl, D.L.; Allen, S.L.; Casper, T.A.

1981-01-01

TMX experimental data on ambipolar potential control and on the accompanying electrostatic confinement are reported. New results on the radial dependence of the central-cell confining potential are given. Radial and axial particle losses as well as scaling of the central-cell axial confinement are discussed

Large-Nc nuclear potential puzzle

International Nuclear Information System (INIS)

Belitsky, A.V.; Cohen, T.D.

2002-01-01

An analysis of the baryon-baryon potential from the point of view of large-N c QCD is performed. A comparison is made between the N c -scaling behavior directly obtained from an analysis at the quark-gluon level to the N c scaling of the potential for a generic hadronic field theory in which it arises via meson exchanges and for which the parameters of the theory are given by their canonical large-N c scaling behavior. The purpose of this comparison is to use large-N c consistency to test the widespread view that the interaction between nuclei arises from QCD through the exchange of mesons. Although at the one- and two-meson exchange level the scaling rules for the potential derived from the hadronic theory matches the quark-gluon level prediction, at the three- and higher-meson exchange level a generic hadronic theory yields a potential which scales with N c faster than that of the quark-gluon theory

[Non-empirical interatomic potentials for transition metals

International Nuclear Information System (INIS)

1993-01-01

The report is divided into the following sections: potential-energy functions for d-band metals, potential-energy functions for aluminides and quasicrystals, electronic structure of complex structures and quasicrystals, potential-energy functions in transition-metal oxides, applications to defect structure and mechanical properties, and basic theory of interatomic potentials

Bioelectric potentials in the soil-plant system

Science.gov (United States)

Pozdnyakov, A. I.

2013-07-01

A detailed study of the electric potentials in the soil-plant system was performed. It was found that the electric potential depends on the plant species and the soil properties. A theoretical interpretation of the obtained data was given. All the plants, independently from their species and their state, always had a negative electric potential relative to the soil. The electric potential of the herbaceous plants largely depended on the leaf area. In some plants, such as burdock ( Arctium lappa) and hogweed ( Heracleum sosnowskyi), the absolute values of the negative electric potential exceeded 100 mV. The electric potential was clearly differentiated by the plant organs: in the flowers, it was lower than in the leaves; in the leaves, it was usually lower than in the leaf rosettes and stems. The electric potentials displayed seasonal dynamics. As a rule, the higher the soil water content, the lower the electric potential of the plants. However, an inverse relationship was observed for dandelions ( Taraxacum officinale). It can be supposed that the electric potential between the soil and the plant characterizes the vital energy of the plant.

Construction of the landscape for multi-stable systems: Potential landscape, quasi-potential, A-type integral and beyond

Science.gov (United States)

Zhou, Peijie; Li, Tiejun

2016-03-01

Motivated by the famous Waddington's epigenetic landscape metaphor in developmental biology, biophysicists and applied mathematicians made different proposals to construct the landscape for multi-stable complex systems. We aim to summarize and elucidate the relationships among these theories from a mathematical point of view. We systematically investigate and compare three different but closely related realizations in the recent literature: the Wang's potential landscape theory from steady state distribution of stochastic differential equations (SDEs), the Freidlin-Wentzell quasi-potential from the large deviation theory, and the construction through SDE decomposition and A-type integral. We revisit that the quasi-potential is the zero noise limit of the potential landscape, and the potential function in the third proposal coincides with the quasi-potential. We compare the difference between local and global quasi-potential through the viewpoint of exchange of limit order for time and noise amplitude. We argue that local quasi-potentials are responsible for getting transition rates between neighboring stable states, while the global quasi-potential mainly characterizes the residence time of the states as the system reaches stationarity. The difference between these two is prominent when the transitivity property is broken. The most probable transition path by minimizing the Onsager-Machlup or Freidlin-Wentzell action functional is also discussed. As a consequence of the established connections among different proposals, we arrive at the novel result which guarantees the existence of SDE decomposition while denies its uniqueness in general cases. It is, therefore, clarified that the A-type integral is more appropriate to be applied to the decomposed SDEs rather than its primitive form as believed by previous researchers. Our results contribute to a deeper understanding of landscape theories for biological systems.

Construction of the landscape for multi-stable systems: Potential landscape, quasi-potential, A-type integral and beyond

International Nuclear Information System (INIS)

Zhou, Peijie; Li, Tiejun

2016-01-01

Motivated by the famous Waddington’s epigenetic landscape metaphor in developmental biology, biophysicists and applied mathematicians made different proposals to construct the landscape for multi-stable complex systems. We aim to summarize and elucidate the relationships among these theories from a mathematical point of view. We systematically investigate and compare three different but closely related realizations in the recent literature: the Wang’s potential landscape theory from steady state distribution of stochastic differential equations (SDEs), the Freidlin-Wentzell quasi-potential from the large deviation theory, and the construction through SDE decomposition and A-type integral. We revisit that the quasi-potential is the zero noise limit of the potential landscape, and the potential function in the third proposal coincides with the quasi-potential. We compare the difference between local and global quasi-potential through the viewpoint of exchange of limit order for time and noise amplitude. We argue that local quasi-potentials are responsible for getting transition rates between neighboring stable states, while the global quasi-potential mainly characterizes the residence time of the states as the system reaches stationarity. The difference between these two is prominent when the transitivity property is broken. The most probable transition path by minimizing the Onsager-Machlup or Freidlin-Wentzell action functional is also discussed. As a consequence of the established connections among different proposals, we arrive at the novel result which guarantees the existence of SDE decomposition while denies its uniqueness in general cases. It is, therefore, clarified that the A-type integral is more appropriate to be applied to the decomposed SDEs rather than its primitive form as believed by previous researchers. Our results contribute to a deeper understanding of landscape theories for biological systems.

Construction of the landscape for multi-stable systems: Potential landscape, quasi-potential, A-type integral and beyond

Energy Technology Data Exchange (ETDEWEB)

Zhou, Peijie, E-mail: cliffzhou@pku.edu.cn; Li, Tiejun, E-mail: tieli@pku.edu.cn [LMAM and School of Mathematical Sciences, Peking University, Beijing 100871 (China)

2016-03-07

Motivated by the famous Waddington’s epigenetic landscape metaphor in developmental biology, biophysicists and applied mathematicians made different proposals to construct the landscape for multi-stable complex systems. We aim to summarize and elucidate the relationships among these theories from a mathematical point of view. We systematically investigate and compare three different but closely related realizations in the recent literature: the Wang’s potential landscape theory from steady state distribution of stochastic differential equations (SDEs), the Freidlin-Wentzell quasi-potential from the large deviation theory, and the construction through SDE decomposition and A-type integral. We revisit that the quasi-potential is the zero noise limit of the potential landscape, and the potential function in the third proposal coincides with the quasi-potential. We compare the difference between local and global quasi-potential through the viewpoint of exchange of limit order for time and noise amplitude. We argue that local quasi-potentials are responsible for getting transition rates between neighboring stable states, while the global quasi-potential mainly characterizes the residence time of the states as the system reaches stationarity. The difference between these two is prominent when the transitivity property is broken. The most probable transition path by minimizing the Onsager-Machlup or Freidlin-Wentzell action functional is also discussed. As a consequence of the established connections among different proposals, we arrive at the novel result which guarantees the existence of SDE decomposition while denies its uniqueness in general cases. It is, therefore, clarified that the A-type integral is more appropriate to be applied to the decomposed SDEs rather than its primitive form as believed by previous researchers. Our results contribute to a deeper understanding of landscape theories for biological systems.

Structural lesions detected by magnetic resonance imaging in the spine of patients with spondyloarthritis - definitions, assessment system, and reference image set

DEFF Research Database (Denmark)

Østergaard, Mikkel; Maksymowych, Walter P; Pedersen, Susanne J

2009-01-01

are assessed at each vertebral endplate at all 23 spinal levels from C2/3 to L5/S1, whereas facet joint lesions are to be assessed by segmental level (cervical, thoracic, and lumbar). CONCLUSION: An anatomy-based set of definitions and an assessment system for structural lesions in the spine of patients......OBJECTIVE: There is no reliable and sensitive magnetic resonance imaging (MRI) assessment system for structural lesions in patients with spondyloarthritis (SpA). We sought to develop and illustrate a detailed anatomy-based set of MRI definitions and an assessment system for structural lesions...... in the spine of patients with SpA. METHODS: MRI definitions of different structural ("chronic") lesions at various anatomical locations in the spine, and an accompanying assessment system, were agreed by consensus within the Canada-Denmark MRI working group. Subsequently, a reference image set...

Matching of motor-sensory modality in the rodent femoral nerve model shows no enhanced effect on peripheral nerve regeneration

Science.gov (United States)

Kawamura, David H.; Johnson, Philip J.; Moore, Amy M.; Magill, Christina K.; Hunter, Daniel A.; Ray, Wilson Z.; Tung, Thomas HH.; Mackinnon, Susan E.

2010-01-01

The treatment of peripheral nerve injuries with nerve gaps largely consists of autologous nerve grafting utilizing sensory nerve donors. Underlying this clinical practice is the assumption that sensory autografts provide a suitable substrate for motoneuron regeneration, thereby facilitating motor endplate reinnervation and functional recovery. This study examined the role of nerve graft modality on axonal regeneration, comparing motor nerve regeneration through motor, sensory, and mixed nerve isografts in the Lewis rat. A total of 100 rats underwent grafting of the motor or sensory branch of the femoral nerve with histomorphometric analysis performed after 5, 6, or 7 weeks. Analysis demonstrated similar nerve regeneration in motor, sensory, and mixed nerve grafts at all three time points. These data indicate that matching of motor-sensory modality in the rat femoral nerve does not confer improved axonal regeneration through nerve isografts. PMID:20122927

The Low Energy Antiproton Ring (LEAR) some months before the start of its particle physics programme

CERN Multimedia

1983-01-01

LEAR [see e.g.: H.Koziol and D. Möhl, Phys. Rep. 403-404 (2004), p.271 and references therein] and its enclosure in the PS South Hall in Jan, 1983, 4 months before the start of its particle physics programme. Visible (in red) are the 90 degree bending magnets consisting of 6 blocks each. Separated from the magnets by short straight sections are the quadrupole doublets (blue with read end-plates). The 4 long straight sections house large equipment like septa for injection/ejection, RF-cavities and later (since 1986) electron cooling and an internal target and its associated detector (JETSET experiment). Two small copper tubes spanning across the ring are coaxial lines transmitting the stochastic cooling signals from pick up to kicker. (see also photos 8205747X, 8207133, 8207541X, 8301550X,8309026X)

Track distortion in a micromegas based large prototype of a Time Projection Chamber for the International Linear Collider

International Nuclear Information System (INIS)

Bhattacharya, Deb Sankar; Majumdar, Nayana; Sarkar, S.; Bhattacharya, S.; Mukhopadhyay, Supratik; Bhattacharya, P.; Attie, D.; Colas, P.; Ganjour, S.; Bhattacharya, Aparajita

2016-01-01

The principal particle tracker at the International Linear Collider (ILC) is planned to be a large Time Projection Chamber (TPC) where different Micro Pattern Gaseous Detector (MPGDs) candidate as the gaseous amplifier. A Micromegas (MM) based TPC can meet the ILC requirement of continuous and precise pattern recognition. Seven MM modules, working as the end-plate of a Large Prototype TPC (LPTPC) installed at DESY, have been tested with a 5 GeV electron beam. Due to the grounded peripheral frame of the MM modules, at low drift, the electric field lines near the detector edge remain no longer parallel to the TPC axis. This causes signal loss along the boundaries of the MM modules as well as distortion in the reconstructed track. In presence of magnetic field, the distorted electric field introduces ExB effect

Nervous system and receptors. Chapter 3.5

International Nuclear Information System (INIS)

Beaumariage, M.L.

1975-01-01

The literature is reviewed for the effects of sulphur-containing radioprotective agents on the nervous system and receptors. Studies of the neurological changes observed in alert animals and their modification by anaesthetics have indicated that a direct effect is exerted on the cortical and subcortical structures. Some local anaesthetic effects may result from nerve endings being squeezed by the edematous papule formed on the site of the injection. MEA and, to a lesser extent, cystamine, competitively block the neuromuscular junction by inhibiting the action of acetylcholine on the motor end-plate. The effects of radioprotective substances on the autonomic nervous system in different species have also been considered. The sensitivity of the chemo- and pressor-sensitive endings of the aortic branch, the carotids and the lungs is not affected by the administration of radioprotective agents. (U.K.)

One-millipound mercury ion thruster

Science.gov (United States)

Hyman, J., Jr.; Dulgeroff, C. R.; Kami, S.; Williamson, W. S.

1975-01-01

A mercury ion thruster has been developed for efficient operation at the nominal 1-mlb thrust level with a specific impulse of about 3,000 sec and a total power consumption of about 120 W. At a beam voltage of 1,200 V and beam current of 72 mA, the discharge chamber operates with a propellant efficiency of 93.8% at an ion-generation energy of 276 eV/ion. The 8-cm diameter thruster advances proven component technology to assure the capability for thruster operation over an accumulated beam-on time in excess of 20,000 hours with a capability for 10,000 on-off duty cycles. Discharge chamber optimization has combined stable current-voltage characteristics with high performance efficiency by careful placement of the discharge cathode near the location of a magnetic-field zero just upstream of the thruster endplate.

Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material

Science.gov (United States)

Wosik, J.; Kranenburg, R. A.; Wolfe, J. C.; Selvamanickam, V.; Salama, K.

1991-01-01

Measurements of the millimeter wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid phase process are reported. The measurements were performed by replacing the endplate of a TE011 cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. It is shown that, for the parallel configuration, the surface resistance at 77 K and 80 GHz is typically near 100 milliohms. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K, and the surface resistance is less than 50 milliohms at 88 K. The effect of microstructure on surface resistance is discussed.

Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3Ox bulk material

International Nuclear Information System (INIS)

Wosik, J.; Kranenburg, R.A.; Wolfe, J.C.; Selvamanickam, V.; Salama, K.

1991-01-01

We report measurements of the millimeter wave surface resistance of grain-aligned YBa 2 Cu 3 O x bulk material grown by a liquid phase process. The measurements were performed by replacing the endplate of a TE 011 cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. We show that, for the parallel configuration, the surface resistance at 77 K and 80 GHz is typically near 100 mΩ. For a very well-aligned sample with a very low density of Y 2 BaCuO y precipitates, measured in the perpendicular configuration, the transition width (10%--90%) is about 2 K and the surface resistance is less than 50 mΩ at 88 K. The effect of microstructure on surface resistance is discussed

Intrasacral rod fixation for pediatric lumbopelvic fusion.

Science.gov (United States)

Ilharreborde, Brice; Mazda, Keyvan

2014-07-01

This paper reports the authors' 19 years experience with pediatric intrasacral rod fixation. After insertion of two cannulated screws in S1 with and an original template guiding them into the anterior third of the endplate, two short fusion rods were inserted into the sacrum according to Jackson's technique distally to S3. In neuromuscular scoliosis, pelvic obliquity was reduced by connecting the proximal and distal constructs, distraction or compression, and in situ rod bending. In children with high-grade spondylolisthesis, lumbosacral kyphosis was reduced by rotation of the sacrum and in situ bending. There were no direct neurological or vascular injuries. The main complication was infection (7%). No pseudarthrosis or significant loss of correction at the lumbosacral junction was observed during follow-up. Intrasacral rod fixation appears to be safe and reliable for lumbopelvic fusion in pediatric patients.

Imaging of lumbar degenerative disk disease: history and current state

International Nuclear Information System (INIS)

Emch, Todd M.; Modic, Michael T.

2011-01-01

One of the most common indications for performing magnetic resonance (MR) imaging of the lumbar spine is the symptom complex thought to originate as a result of degenerative disk disease. MR imaging, which has emerged as perhaps the modality of choice for imaging degenerative disk disease, can readily demonstrate disk pathology, degenerative endplate changes, facet and ligamentous hypertrophic changes, and the sequelae of instability. Its role in terms of predicting natural history of low back pain, identifying causality, or offering prognostic information is unclear. As available modalities for imaging the spine have progressed from radiography, myelography, and computed tomography to MR imaging, there have also been advances in spine surgery for degenerative disk disease. These advances are described in a temporal context for historical purposes with a focus on MR imaging's history and current state. (orig.)

Parametric study on the behaviour of bolted composite connections

Directory of Open Access Journals (Sweden)

M. N. Kataoka

Full Text Available The studied connections are composed of concrete filled steel tubes (CFT connected to composite beams by passing through bolts, endplates and steel deck, which also contributes to support the applied loads. The parametric analysis presented in this work is based on numerical simulations performed with software TNO Diana, using experimental results to calibrate the reference numerical model. The influence of three main parameters, being them the bolts diameter, the slab height and the beams cross section, was evaluated. According to the obtained bending moment versus rotation curves, it was concluded that, among the three parameters analyzed, the most important one was the bolts diameter. About the beams cross section, inconclusive results were achieved, probably due to the incompatibility between the 16 mm bolts and the robust beam cross sections considered in the parametric analysis.

The glial cell line-derived neurotrophic factor (GDNF) does not acutely change acetylcholine release in developing and adult neuromuscular junction.

Science.gov (United States)

Garcia, Neus; Santafé, Manel M; Tomàs, Marta; Lanuza, Maria A; Besalduch, Nuria; Priego, Merche; Tomàs, Josep

2010-08-16

We use immunocytochemistry to show that the trophic molecule glial cell line-derived neurotrophic factor (GDNF) and its receptor GDNF family receptor alpha-1 (GFRalpha-1) are present in both neonatal (P6) and adult (P45) rodent neuromuscular junctions (NMJ) colocalized with several synaptic markers. However, incubation with exogenous GDNF (10-200ng/ml, 1-3h), does not affect spontaneous ACh release. Moreover, GDNF does not change the size of the evoked ACh release from the weak and the strong axonal inputs on dually innervated postnatal endplates nor in the most developed singly-innervated synapses at P6 and P45. Our findings indicate that GDNF (unlike neurotrophins) does not acutely modulate transmitter release during the developmental process of synapse elimination nor as the NMJ matures. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Potential for waste reduction

International Nuclear Information System (INIS)

Warren, J.L.

1990-01-01

The author focuses on wastes considered hazardous under the Resource Conservation and Recovery Act. This chapter discusses wastes that are of interest as well as the factors affecting the quantity of waste considered available for waste reduction. Estimates are provided of the quantities of wastes generated. Estimates of the potential for waste reduction are meaningful only to the extent that one can understand the amount of waste actually being generated. Estimates of waste reduction potential are summarized from a variety of government and nongovernment sources

A new generic model potential for mesogenic systems: square well line potential of variable range.

Science.gov (United States)

Varga, Szabolcs; Vesely, Franz J

2009-11-21

A single-site pair potential is derived to approximate the linear n-site square well interaction. The resulting square well line (SWL) potential is analytical, fairly smooth, and reproduces the distance and orientation dependence of the multisite pair energy. It contains only three control parameters n, L, and s(2), in addition to the units of length s(1) and energy epsilon. The advantages of the new model over the traditional potentials such as Gay-Berne and Kihara are that n, L, and s(2) are physically meaningful quantities and that no additional adjustable parameters are introduced. With the SWL potential even very long square well chain molecules may be treated in Monte Carlo (MC) simulations; moreover the model is well suited for perturbation theory. Using Onsager-like theories we test the effect of molecular elongation, temperature, and the range of the square well potential on the vapor-liquid and nematic-smectic A (NS) phase transitions. We find that the vapor-liquid binodal of the SWL fluid is in good agreement with MC results for square well dumbbells. For repulsive SWL particles, varying the interaction range s(2) results in a similar effect on the NS transition as the change in the ionic strength in a real suspension of fd viruses.

SUSY-hierarchy of one-dimensional reflectionless potentials

International Nuclear Information System (INIS)

Maydanyuk, Sergei P.

2005-01-01

A class of one-dimensional reflectionless potentials is studied. It is found that all possible types of the reflectionless potentials can be combined into one SUSY-hierarchy with a constant potential. An approach for determination of a general form of the reflectionless potential on the basis of construction of such a hierarchy by the recurrent method is proposed. A general integral form of interdependence between superpotentials with neighboring numbers of this hierarchy, opening a possibility to find new reflectionless potentials, is found and has a simple analytical view. It is supposed that any possible type of the reflectionless potential can be expressed through finite number of elementary functions (unlike some presentations of the reflectionless potentials, which are constructed on the basis of soliton solutions or are shape invariant in one or many steps with involving scaling of parameters, and are expressed through series). An analysis of absolute transparency existence for the potential which has the inverse power dependence on space coordinate (and here tunneling is possible), i.e., which has the form V (x) = ± α/ vertical bar x-x 0 vertical bar n (where α and x 0 are constants, n is natural number), is fulfilled. It is shown that such a potential can be reflectionless at n = 2 only. A SUSY-hierarchy of the inverse power reflectionless potentials is constructed. Isospectral expansions of this hierarchy are analyzed

Bayesian analysis of the kinetics of quantal transmitter secretion at the neuromuscular junction.

Science.gov (United States)

Saveliev, Anatoly; Khuzakhmetova, Venera; Samigullin, Dmitry; Skorinkin, Andrey; Kovyazina, Irina; Nikolsky, Eugeny; Bukharaeva, Ellya

2015-10-01

The timing of transmitter release from nerve endings is considered nowadays as one of the factors determining the plasticity and efficacy of synaptic transmission. In the neuromuscular junction, the moments of release of individual acetylcholine quanta are related to the synaptic delays of uniquantal endplate currents recorded under conditions of lowered extracellular calcium. Using Bayesian modelling, we performed a statistical analysis of synaptic delays in mouse neuromuscular junction with different patterns of rhythmic nerve stimulation and when the entry of calcium ions into the nerve terminal was modified. We have obtained a statistical model of the release timing which is represented as the summation of two independent statistical distributions. The first of these is the exponentially modified Gaussian distribution. The mixture of normal and exponential components in this distribution can be interpreted as a two-stage mechanism of early and late periods of phasic synchronous secretion. The parameters of this distribution depend on both the stimulation frequency of the motor nerve and the calcium ions' entry conditions. The second distribution was modelled as quasi-uniform, with parameters independent of nerve stimulation frequency and calcium entry. Two different probability density functions for the distribution of synaptic delays suggest at least two independent processes controlling the time course of secretion, one of them potentially involving two stages. The relative contribution of these processes to the total number of mediator quanta released depends differently on the motor nerve stimulation pattern and on calcium ion entry into nerve endings.

Adaptation of slow myofibers: the effect of sustained BDNF treatment of extraocular muscles in infant nonhuman primates.

Science.gov (United States)

Willoughby, Christy L; Fleuriet, Jérome; Walton, Mark M; Mustari, Michael J; McLoon, Linda K

2015-06-01

We evaluated promising new treatment options for strabismus. Neurotrophic factors have emerged as a potential treatment for oculomotor disorders because of diverse roles in signaling to muscles and motor neurons. Unilateral treatment with sustained release brain-derived neurotrophic factor (BDNF) to a single lateral rectus muscle in infant monkeys was performed to test the hypothesis that strabismus would develop in correlation with extraocular muscle (EOM) changes during the critical period for development of binocularity. The lateral rectus muscles of one eye in two infant macaques were treated with sustained delivery of BDNF for 3 months. Eye alignment was assessed using standard photographic methods. Muscle specimens were analyzed to examine the effects of BDNF on the density, morphology, and size of neuromuscular junctions, as well as myofiber size. Counts were compared to age-matched controls. No change in eye alignment occurred with BDNF treatment. Compared to control muscle, neuromuscular junctions on myofibers expressing slow myosins had a larger area. Myofibers expressing slow myosin had larger diameters, and the percentage of myofibers expressing slow myosins increased in the proximal end of the muscle. Expression of BDNF was examined in control EOM, and observed to have strongest immunoreactivity outside the endplate zone. We hypothesize that the oculomotor system adapted to sustained BDNF treatment to preserve normal alignment. Our results suggest that BDNF treatment preferentially altered myofibers expressing slow myosins. This implicates BDNF signaling as influencing the slow twitch properties of EOM.

Congenital Myasthenic Syndrome in a Mixed Breed Dog

Directory of Open Access Journals (Sweden)

Theresa J. Blakey

2017-10-01

Full Text Available A 6-month-old, male, intact mixed breed dog was presented for a 3-month history of progressive generalized weakness. Neurologic examination revealed non-ambulatory tetraparesis, weakness of the head and neck, and decreased withdrawal reflexes in all limbs consistent with a generalized neuromuscular disorder. Electromyography and motor nerve conduction velocity were normal. Repetitive nerve stimulation showed a decremental response of the compound muscle action potential with improvement upon intravenous administration of edrophonium chloride. The serum acetylcholine receptor (AChR antibody titer was within reference range. Cerebrospinal fluid analysis was unremarkable. A presumptive diagnosis of post-synaptic congenital myasthenic syndrome (CMS was made. Treatment with pyridostigmine bromide was initiated with titrated increases in dosage resulting in an incomplete improvement in clinical signs. The dog was euthanized 2 months after initiation of treatment due to poor quality of life. Immunostaining for localization of antibodies against end-plate proteins in muscle biopsies was negative. Immunofluorescence staining for AChRs in external intercostal muscle biopsies showed absence of AChRs and biochemical quantitation showed a markedly decreased concentration of AChRs with no detectable AChR-bound autoantibody which confirmed the diagnosis of a CMS. Evaluation for the CHRNE mutation previously identified as the causative mutation of CMS in Jack Russell Terriers was performed and was negative. This is the first reported confirmed case of CMS in a mixed breed dog and provides a review of typical clinical and diagnostic findings as well as treatment considerations.

Testing static quark-antiquark potentials with bottomonium

International Nuclear Information System (INIS)

Lichtenberg, D.B.; Predazzi, E.; Roncaglia, R.; Rosso, M.; Wills, J.G.

1989-01-01

We investigate the question of whether experimental data on the energy levels of bottomonium can discriminate between quark-antiquark potentials which are motivated by what we know about QCD and potentials which are purely phenomenological. We restrict ourselves to bottomonium because, of all the quarkonia observed thus far, bottomonium is the least relativistic and therefore the best testing ground for the static quarkonium potential. We consider two potentials whose functional form is motivated from perturbative QCD at short quark-antiquark separations and from nonperturbative lattice QCD at large separations. We also consider three strictly phenomenological potentials. We find that the best of the three phenomenological potentials, which has never been previously used, fits the spin-averaged data at least as well as the best of the QCD-motivated potentials. We propose further measurements on bottomium energy levels to provide additional tests. (orig.)

Increasing the applicability of density functional theory. IV. Consequences of ionization-potential improved exchange-correlation potentials.

Science.gov (United States)

Verma, Prakash; Bartlett, Rodney J

2014-05-14

This paper's objective is to create a "consistent" mean-field based Kohn-Sham (KS) density functional theory (DFT) meaning the functional should not only provide good total energy properties, but also the corresponding KS eigenvalues should be accurate approximations to the vertical ionization potentials (VIPs) of the molecule, as the latter condition attests to the viability of the exchange-correlation potential (VXC). None of the prominently used DFT approaches show these properties: the optimized effective potential VXC based ab initio dft does. A local, range-separated hybrid potential cam-QTP-00 is introduced as the basis for a "consistent" KS DFT approach. The computed VIPs as the negative of KS eigenvalue have a mean absolute error of 0.8 eV for an extensive set of molecule's electron ionizations, including the core. Barrier heights, equilibrium geometries, and magnetic properties obtained from the potential are in good agreement with experiment. A similar accuracy with less computational efforts can be achieved by using a non-variational global hybrid variant of the QTP-00 approach.

Exact exchange-correlation potential and approximate exchange potential in terms of density matrices

International Nuclear Information System (INIS)

Holas, A.; March, N.H.

1995-01-01

An exact expression in terms of density matrices (DM) is derived for δF[n]/δn(r), the functional derivative of the Hohenberg-Kohn functional. The derivation starts from the differential form of the virial theorem, obtained here for an electron system with arbitrary interactions, and leads to an expression taking the form of an integral over a path that can be chosen arbitrarily. After applying this approach to the equivalent system of noninteracting electrons (Slater-Kohn-Sham scheme) and combining the corresponding result with the previous one, an exact expression for the exchange-correlation potential v xc (r) is obtained which is analogous in character to that for δF[n]/δn(r), but involving, besides the interacting-system DMs, also the noninteracitng DMs. Equating the former DMs to the latter ones, we reduce the result for the exact v xc (r) to that for an approximate exchange-only potential v x (r). This leads naturally to the Harbola-Sahni exchange-only potential

Radiofrequency-dressed-state potentials for neutral atoms

DEFF Research Database (Denmark)

Hofferberth, S.; Lesanovsky, Igor; Fischer, B.

2006-01-01

Potentials for atoms can be created by external fields acting on properties such as magnetic moment, charge, polarizability, or by oscillating fields that couple internal states. The most prominent realization of the latter is the optical dipole potential formed by coupling ground and electronica......Potentials for atoms can be created by external fields acting on properties such as magnetic moment, charge, polarizability, or by oscillating fields that couple internal states. The most prominent realization of the latter is the optical dipole potential formed by coupling ground...... and electronically excited states of an atom with light. Here, we present an extensive experimental analysis of potentials derived from radiofrequency (RF) coupling of electronic ground states. The coupling is magnetic and the vector character allows the design of versatile microscopic state-dependent potential...... landscapes. Compared with standard magnetic trapping, we find no additional heating or (collisional) loss up to densities of 1015 atoms cm-3. We demonstrate robust evaporative cooling in RF potentials, which allows easy production of Bose-Einstein condensates in complex potentials. Altogether, this makes RF...

Microscopic optical potential at medium energies

International Nuclear Information System (INIS)

Malecki, A.

1979-01-01

The problems concerning a microscopic optical model for the elastic nuclear collisions at medium energies are discussed. We describe the method for constructing the optical potential which makes use of the particular properties of quantum scattering in the eikonal limit. The resulting potential is expressed in terms of the nuclear wave functions and the nucleon-nucleon scattering amplitudes. This potential has a dynamic character since by including the effects of multiple scattering it allows for the possibility of intermediate excitations of the projectile and target nuclei. The use of the potential in the exact wave equation accounts for the most important mechanisms present in the collisions between composite particles. The microscopic optical model was successfully applied in the analysis of elastic scattering of protons and α-particles on atomic nuclei in the energy range of 300-1000 MeV/nucleon. The dynamic optical potential in this case represents a considerable improvement over the eikonal Glauber model and the static optical potential of Watson. The possibilities to extend the microscopic description of the proton-nucleus interaction by considering the spin dependence of the elementary amplitude and the Majorana exchange effects were investigated. (author)

Atom-surface potentials and atom interferometry

International Nuclear Information System (INIS)

Babb, J.F.

1998-01-01

Long-range atom-surface potentials characterize the physics of many actual systems and are now measurable spectroscopically in deflection of atomic beams in cavities or in reflection of atoms in atomic fountains. For a ground state, spherically symmetric atom the potential varies as -1/R 3 near the wall, where R is the atom-surface distance. For asymptotically large distances the potential is weaker and goes as -1/R 4 due to retardation arising from the finite speed of light. This diminished interaction can also be interpreted as a Casimir effect. The possibility of measuring atom-surface potentials using atomic interferometry is explored. The particular cases studied are the interactions of a ground-state alkali-metal atom and a dielectric or a conducting wall. Accurate descriptions of atom-surface potentials in theories of evanescent-wave atomic mirrors and evanescent wave-guided atoms are also discussed. (author)

On transparent potentials: a Born approximation study

International Nuclear Information System (INIS)

Coudray, C.

1980-01-01

In the frame of the scattering inverse problem at fixed energy, a class of potentials transparent in Born approximation is obtained. All these potentials are spherically symmetric and are oscillating functions of the reduced radial variable. Amongst them, the Born approximation of the transparent potential of the Newton-Sabatier method is found. In the same class, quasi-transparent potentials are exhibited. Very general features of potentials transparent in Born approximation are then stated. And bounds are given for the exact scattering amplitudes corresponding to most of the potentials previously exhibited. These bounds, obtained at fixed energy, and for large values of the angular momentum, are found to be independent on the energy

Measurement of human potential in organizations

Directory of Open Access Journals (Sweden)

Rosa María Fuchs Ángeles

2015-09-01

Full Text Available Companies around the world are concerned about talent management in their organizations. The concern is to retain talented employees and this may not be possible if they are not properly identified. Performance and potential evaluations become then important. Performance evaluations qualify the historical record of the employee, so their measurement is provided. However, measuring the potential performance assesses potential future charges, therefore it is not a simple task. In this paper, characteristics evaluated in potential employees and tools that are commonly used are presented. Also, the case of four companies operating in Peru is shown.

Phenomenological aspects of nonrelativistic potential models

International Nuclear Information System (INIS)

Lucha, W.; Schoeberl, F.F.

1989-01-01

This review reports on the description of hardrons as bound states of quarks by nonrelativistic potential models. It contains a brief sketch of the way in which information on the form of the inter-quark potential may be gained from quantum chromodynamics, proofs of some general theorems related to the potential-model approach, a discussion of the significance of the treatment of bound states consisting of relativistically-moving constituents by the nonrelativistic Schroedinger formalism, as well as a brief survey of the motivations for the various proposed potential models. Finally, it illustrates the application of the developed theoretical framework at a few selected examples. 60 refs., 8 figs., 17 tabs. (Authors)

Potential photosynthesis of crop surfaces.

NARCIS (Netherlands)

Wit, de C.T.

1959-01-01

A formula for calculating the potential photosynthesis of a closed crop surface is proposed, assuming that the leaves of the crop are not arranged in any definite direction. In the Netherlands, values for potential photosynthesis vary from 290 kg. CH2O/ha./day in June to 50 kg./ha./day in December.

Velocity Potential in Engineering Hydraulics versus Force Potential in Groundwater Dynamics

Science.gov (United States)

Weyer, K.

2013-12-01

Within engineering practice, the calculation of subsurface flow is dominated by the mathematical pseudo-physics of the engineer's adaptation of continuum methods to mechanics. Continuum mechanics rose to prominence in the 19th century in an successful attempt to solve practical engineering problems. To that end were put in place quite a number of simplifications in geometry and the properties of water and other fluids, as well as simplifications of Darcy's equation, in order to find reasonable answers to practical problems by making use of analytical equations. The proof of the correctness of the approach and its usefulness was in the practicability of results obtained. In the 1930s, a diametrically-opposed duality developed in the theoretical derivation of the laws of subsurface fluid flow between Muskat's (1937) velocity potential (engineering hydraulics) and Hubbert's (1940) force potential. The conflict between these authors lasted a lifetime. In the end Hubbert stated on one occasion that Muskat formulates a refined mathematics but does not know what it means in physical terms. In this author's opinion that can still be said about the application of continuum mechanics by engineers to date, as for example to CO2 sequestration, regional groundwater flow, oil sands work, and geothermal studies. To date, engineering hydraulics is best represented by Bear (1972) and de Marsily (1986). In their well-known textbooks, both authors refer to Hubbert's work as the proper way to deal with the physics of compressible fluids. Water is a compressible fluid. The authors then ignore, however, their own insights (de Marsily states so explicitly, Bear does not) and proceed to deal with water as an incompressible fluid. At places both authors assume the pressure gradients to be the main driving force for flow of fluids in the subsurface. That is not, however, the case. Instead the pressure potential forces are caused by compression initiated by unused gravitational energy not

Chloride equilibrium potential in salamander cones

Directory of Open Access Journals (Sweden)

Bryson Eric J

2004-12-01

Full Text Available Abstract Background GABAergic inhibition and effects of intracellular chloride ions on calcium channel activity have been proposed to regulate neurotransmission from photoreceptors. To assess the impact of these and other chloride-dependent mechanisms on release from cones, the chloride equilibrium potential (ECl was determined in red-sensitive, large single cones from the tiger salamander retinal slice. Results Whole cell recordings were done using gramicidin perforated patch techniques to maintain endogenous Cl- levels. Membrane potentials were corrected for liquid junction potentials. Cone resting potentials were found to average -46 mV. To measure ECl, we applied long depolarizing steps to activate the calcium-activated chloride current (ICl(Ca and then determined the reversal potential for the current component that was inhibited by the Cl- channel blocker, niflumic acid. With this method, ECl was found to average -46 mV. In a complementary approach, we used a Cl-sensitive dye, MEQ, to measure the Cl- flux produced by depolarization with elevated concentrations of K+. The membrane potentials produced by the various high K+ solutions were measured in separate current clamp experiments. Consistent with electrophysiological experiments, MEQ fluorescence measurements indicated that ECl was below -36 mV. Conclusions The results of this study indicate that ECl is close to the dark resting potential. This will minimize the impact of chloride-dependent presynaptic mechanisms in cone terminals involving GABAa receptors, glutamate transporters and ICl(Ca.

Handbook methane potential; Handbok metanpotential

Energy Technology Data Exchange (ETDEWEB)

Carlsson, My (AnoxKaldnes AB (Sweden)); Schnurer, Anna (Swedish Univ. of Agricultural Sciences, Uppsala (Sweden))

2011-07-15

Before using a organic material for biogas production it is essential to evaluate the methane production potential. The methane potential is one important tool possible to use during planning of new plants but also when new materials are considered for already running biogas plants. The chemical composition of different organic material varies extensively and this will have an impact on both the degradability and the methane potential. Information about the methane potential of a specific material can sometimes be found in the literature or can be calculated after a chemical/ physical or biological characterization. Here, the BMP test (Biochemical Methane Potential) is a commonly used method. Today the BMP test is a commonly used method to determine the methane potential. Many national and international research groups, consultants as well as personal at biogas plants are using this method and there is a lot of data available in the literature from such tests. In addition there are several protocols giving guidelines on how to execute a BMP-test. The BMP-test is performed in many different ways, not always under optimized conditions, and there is a lack of information on how to interpret the obtained data. This report summarizes knowledge from the literature and the experience from a Swedish referee group, consisting of persons being active performers of BMP-tests. The report does not include a standardized protocol as the procedure can be performed in different ways depending on available equipment and on the type of material to be tested. Instead the report discusses different factors of great importance for a successful test giving reliable results. The report also summarizes important information concerning the interpretation and how to present results in order to allow comparison of data from different test.

Electromagnetic potentials without gauge transformations

International Nuclear Information System (INIS)

Chubykalo, A; Espinoza, A; Alvarado Flores, R

2011-01-01

In this paper, we show that the use of the Helmholtz theorem enables the derivation of uniquely determined electromagnetic potentials without the necessity of using gauge transformation. We show that the electromagnetic field comprises two components, one of which is characterized by instantaneous action at a distance, whereas the other propagates in retarded form with the velocity of light. In our attempt to show the superiority of the new proposed method to the standard one, we argue that the action-at-a-distance components cannot be considered as a drawback of our method, because the recommended procedure for eliminating the action at a distance in the Coulomb gauge leads to theoretical subtleties that allow us to say that the needed gauge transformation is not guaranteed. One of the theoretical consequences of this new definition is that, in addition to the electric E and magnetic B fields, the electromagnetic potentials are real physical quantities. We show that this property of the electromagnetic potentials in quantum mechanics is also a property of the electromagnetic potentials in classical electrodynamics.

The rho-exchange isovector parity-violating potential

International Nuclear Information System (INIS)

McKellar, B.H.J.

1979-01-01

It is shown that the rho-exchange isovector parity-violating potential is constrained by PCAC to be much weaker than the π-exchange potential and much weaker than recently proposed by Galic et al (J. Phys. G.; 5: L113 (1979)). This potential does not therefore provide a mechanism for suppressing enhanced neutral-current effects in the π-exchange potential. (author)

Miscellaneous conditions and future potential

International Nuclear Information System (INIS)

Berquist, T.H.; Ehman, R.L.; Richardson, M.L.; Helms, C.A.

1987-01-01

The previous chapters have discussed basic principles and the types of musculoskeletal pathology that have been most extensively studied with magnetic resonance (MR) techniques. MR has also demonstrated significant potential in other areas, but experience is more limited. Despite this limited experience, the potential application of MR imaging in these areas is discussed in this paper

Revisiting the argument from fetal potential

Directory of Open Access Journals (Sweden)

Manninen Bertha

2007-05-01

Full Text Available Abstract One of the most famous, and most derided, arguments against the morality of abortion is the argument from potential, which maintains that the fetus' potential to become a person and enjoy the valuable life common to persons, entails that its destruction is prima facie morally impermissible. In this paper, I will revisit and offer a defense of the argument from potential. First, I will criticize the classical arguments proffered against the importance of fetal potential, specifically the arguments put forth by philosophers Peter Singer and David Boonin, by carefully unpacking the claims made in these arguments and illustrating why they are flawed. Secondly, I will maintain that fetal potential is morally relevant when it comes to the morality of abortion, but that it must be accorded a proper place in the argument. This proper place, however, cannot be found until we first answer a very important and complex question: we must first address the issue of personal identity, and when the fetus becomes the type of being who is relevantly identical to a future person. I will illustrate why the question of fetal potential can only be meaningfully addressed after we have first answered the question of personal identity and how it relates to the human fetus.

Combining a reactive potential with a harmonic approximation for molecular dynamics simulation of failure: construction of a reduced potential

Science.gov (United States)

Tejada, I. G.; Brochard, L.; Stoltz, G.; Legoll, F.; Lelièvre, T.; Cancès, E.

2015-01-01

Molecular dynamics is a simulation technique that can be used to study failure in solids, provided the inter-atomic potential energy is able to account for the complex mechanisms at failure. Reactive potentials fitted on ab initio results or on experimental values have the ability to adapt to any complex atomic arrangement and, therefore, are suited to simulate failure. But the complexity of these potentials, together with the size of the systems considered, make simulations computationally expensive. In order to improve the efficiency of numerical simulations, simpler harmonic potentials can be used instead of complex reactive potentials in the regions where the system is close to its ground state and a harmonic approximation reasonably fits the actual reactive potential. However the validity and precision of such an approach has not been investigated in detail yet. We present here a methodology for constructing a reduced potential and combining it with the reactive one. We also report some important features of crack propagation that may be affected by the coupling of reactive and reduced potentials. As an illustrative case, we model a crystalline two-dimensional material (graphene) with a reactive empirical bond-order potential (REBO) or with harmonic potentials made of bond and angle springs that are designed to reproduce the second order approximation of REBO in the ground state. We analyze the consistency of this approximation by comparing the mechanical behavior and the phonon spectra of systems modeled with these potentials. These tests reveal when the anharmonicity effects appear. As anharmonic effects originate from strain, stress or temperature, the latter quantities are the basis for establishing coupling criteria for on the fly substitution in large simulations.

Solution of Dirac equation for Eckart potential and trigonometric Manning Rosen potential using asymptotic iteration method

International Nuclear Information System (INIS)

Arum Sari, Resita; Suparmi, A; Cari, C

2016-01-01

The Dirac equation for Eckart potential and trigonometric Manning Rosen potential with exact spin symmetry is obtained using an asymptotic iteration method. The combination of the two potentials is substituted into the Dirac equation, then the variables are separated into radial and angular parts. The Dirac equation is solved by using an asymptotic iteration method that can reduce the second order differential equation into a differential equation with substitution variables of hypergeometry type. The relativistic energy is calculated using Matlab 2011. This study is limited to the case of spin symmetry. With the asymptotic iteration method, the energy spectra of the relativistic equations and equations of orbital quantum number l can be obtained, where both are interrelated between quantum numbers. The energy spectrum is also numerically solved using the Matlab software, where the increase in the radial quantum number n r causes the energy to decrease. The radial part and the angular part of the wave function are defined as hypergeometry functions and visualized with Matlab 2011. The results show that the disturbance of a combination of the Eckart potential and trigonometric Manning Rosen potential can change the radial part and the angular part of the wave function. (paper)

Research potential and cognitive features of students.

Directory of Open Access Journals (Sweden)

Bordovskaia N.V.

2014-12-01

Full Text Available This article examines the theoretical and methodological justifications for studying students’ research potential. It presents proof of the isomorphic nature of human research activity and research potential as well as of the fluid nature of its development: from research-like behavior to science-based research activity. It defines three functional components (motivational, cognitive, and behavioral that form the structure of research potential. It further presents the results of empirically studying the cognitive features of master’s students possessing different levels of research potential. It provides data on the dynamics of research-potential components at different educational levels (bachelor’s and master’s programs. Special attention is given to a comparative analysis of evaluations by research tutors regarding their students’ research potential and of the indicators obtained using psychodiagnostic methods.

Functional and histopathological identification of the respiratory failure in a DMSXL transgenic mouse model of myotonic dystrophy

Directory of Open Access Journals (Sweden)

Petrica-Adrian Panaite

2013-05-01

Acute and chronic respiratory failure is one of the major and potentially life-threatening features in individuals with myotonic dystrophy type 1 (DM1. Despite several clinical demonstrations showing respiratory problems in DM1 patients, the mechanisms are still not completely understood. This study was designed to investigate whether the DMSXL transgenic mouse model for DM1 exhibits respiratory disorders and, if so, to identify the pathological changes underlying these respiratory problems. Using pressure plethysmography, we assessed the breathing function in control mice and DMSXL mice generated after large expansions of the CTG repeat in successive generations of DM1 transgenic mice. Statistical analysis of breathing function measurements revealed a significant decrease in the most relevant respiratory parameters in DMSXL mice, indicating impaired respiratory function. Histological and morphometric analysis showed pathological changes in diaphragmatic muscle of DMSXL mice, characterized by an increase in the percentage of type I muscle fibers, the presence of central nuclei, partial denervation of end-plates (EPs and a significant reduction in their size, shape complexity and density of acetylcholine receptors, all of which reflect a possible breakdown in communication between the diaphragmatic muscles fibers and the nerve terminals. Diaphragm muscle abnormalities were accompanied by an accumulation of mutant DMPK RNA foci in muscle fiber nuclei. Moreover, in DMSXL mice, the unmyelinated phrenic afferents are significantly lower. Also in these mice, significant neuronopathy was not detected in either cervical phrenic motor neurons or brainstem respiratory neurons. Because EPs are involved in the transmission of action potentials and the unmyelinated phrenic afferents exert a modulating influence on the respiratory drive, the pathological alterations affecting these structures might underlie the respiratory impairment detected in DMSXL mice. Understanding

Verification of the SLC wake potentials

International Nuclear Information System (INIS)

Bane, K.; Weiland, T.

1983-01-01

The accurate knowledge of the monopole, dipole, and quadrupole wake potentials is essential for SLC. These wake potentials were previously computed by the modal method. The time domain code TBCI allows independent verification of these results. This comparison shows that the two methods agree to within 10% for bunch lengths down to 1 mm. TBCI results also indicate that rounding the irises gives at least a 10% reduction in the wake potentials

Influence of the potential well and the potential barrier on the density distribution of confined-model fluids

CERN Document Server

Lee, B H; Lee, C H; Seong Baek Seok

2000-01-01

A density functional perturbative approximation, which is based on the density functional expansion of the one-particle direct correlation function of model fluids with respect to the bulk density, has been employed to investigate the influence of the potential well and the potential barrier on the density behavior of confined-model fluids. The mean spherical approximation has been used to calculate the two-particle direct correlation function of the model fluids. At lower densities, the density distributions are strongly affected by the barrier height and the well depth of the model potential, the contribution from the short-range repulsive part being especially important. However, the effects of the barrier height and the well depth of the model potential decrease with increasing bulk density. The calculated results also show that in the region where the effect of the wall-fluid interaction is relatively weak, the square-barrier part of the model potential leads to a nonuniformity in the density distributio...

Imaging Mitochondrial Redox Potential and Its Possible Link to Tumor Metastatic Potential

Science.gov (United States)

Li, Lin Z.

2012-01-01

Cellular redox states can regulate cell metabolism, growth, differentiation, motility, apoptosis, signaling pathways, and gene expressions etc. Growing body of literature suggest importance of redox status for cancer progression. While most studies on redox state were done on cells and tissue lysates, it is important to understand the role of redox state in tissue in vivo/ex vivo and image its heterogeneity. Redox scanning is a clinically-translatable method for imaging tissue mitochondrial redox potential with a submillimeter resolution. Redox scanning data in mouse models of human cancers demonstrate a correlation between mitochondrial redox state and tumor metastatic potential. I will discuss the significance of this correlation and possible directions for future research. PMID:22895837

Deposition potential of polonium

Energy Technology Data Exchange (ETDEWEB)

Heal, H. G.

1948-11-23

The cathodic deposition potential for polonium in concentrations of 10{sup -13} normal and 8 x 10{sup -13} normal, the former being 100-fold smaller than the smallest concentrations previously studied, has been determined. The value is 0.64 volt on the hydrogen scale. Considering the various ways in which the graphs can reasonably be drawn, we consider the maximum possible error to be of the order of +- 0.03 volt. There is apparently no shift of deposition potential between concentrations of 10{sup -8} and 10{sup -13} normal, indicating that the Nernst equation is not applicable in these circumstances.

Dual Eligibles and Potentially Avoidable Hospitalizations

Data.gov (United States)

U.S. Department of Health & Human Services — About 25 percent of the hospitalizations for dual eligible beneficiaries in 2005 were potentially avoidable. Medicare and Medicaid spending for those potentially...

Neutron and proton optical potentials

International Nuclear Information System (INIS)

Hansen, L.F.

1985-11-01

The neutron and proton optical model potentials (OMP) are discussed in terms of microscopic (MOMP) and phenomenological (POMP) models. For the MOMP, two approaches are discussed, the nucleus matter approach [Jeukenne-Lejeune-Mahaux (JLM) and Brieva-Rook-von Geramb (BRVG), potentials] and the finite nuclei approach (Osterfeld and Madsen). For the POMP, the Lane charge-exchange potential and its validity over a wide mass range is reviewed. In addition to the Lane symmetry term, the Coulomb correction to both the real and imaginary parts of the OMP is discussed for the above models. The use of the OMP to calculate collective inelastic scattering and observed differences between the neutron- and proton-deformation parameters is also illustrated. 25 refs., 3 figs

Dynamical equations for the optical potential

International Nuclear Information System (INIS)

Kowalski, K.L.

1981-01-01

Dynamical equations for the optical potential are obtained starting from a wide class of N-particle equations. This is done with arbitrary multiparticle interactions to allow adaptation to few-body models of nuclear reactions and including all effects of nucleon identity. Earlier forms of the optical potential equations are obtained as special cases. Particular emphasis is placed upon obtaining dynamical equations for the optical potential from the equations of Kouri, Levin, and Tobocman including all effects of particle identity

Electrode breakdown potentials in MHD plasmas

International Nuclear Information System (INIS)

Sodha, M.S.; Raju, G.V.R.; Kumar, A.S.; Gupta, Bhumesh

1988-01-01

Electrode breakdown potentials and current densities have been calculated for both the thermionically electron emitting and non-emitting cathodes. Calculated values have been compared with the available experimental results. It is found that the cathode potential drop for the breakdown is almost unaffected by the emission. However, both the total potential difference between the anode and the cathode and the current density at the breakdown are higher for electron-emitting cathodes than for non-emitting cathodes. (author)

Conduction velocity of antigravity muscle action potentials.

Science.gov (United States)

Christova, L; Kosarov, D; Christova, P

1992-01-01

The conduction velocity of the impulses along the muscle fibers is one of the parameters of the extraterritorial potentials of the motor units allowing for the evaluation of the functional state of the muscles. There are no data about the conduction velocities of antigravity muscleaction potentials. In this paper we offer a method for measuring conduction velocity of potentials of single MUs and the averaged potentials of the interference electromiogram (IEMG) lead-off by surface electrodes from mm. sternocleidomastoideus, trapezius, deltoideus (caput laterale) and vastus medialis. The measured mean values of the conduction velocity of antigravity muscles potentials can be used for testing the functional state of the muscles.

A Gaussian Approximation Potential for Silicon

Science.gov (United States)

Bernstein, Noam; Bartók, Albert; Kermode, James; Csányi, Gábor

We present an interatomic potential for silicon using the Gaussian Approximation Potential (GAP) approach, which uses the Gaussian process regression method to approximate the reference potential energy surface as a sum of atomic energies. Each atomic energy is approximated as a function of the local environment around the atom, which is described with the smooth overlap of atomic environments (SOAP) descriptor. The potential is fit to a database of energies, forces, and stresses calculated using density functional theory (DFT) on a wide range of configurations from zero and finite temperature simulations. These include crystalline phases, liquid, amorphous, and low coordination structures, and diamond-structure point defects, dislocations, surfaces, and cracks. We compare the results of the potential to DFT calculations, as well as to previously published models including Stillinger-Weber, Tersoff, modified embedded atom method (MEAM), and ReaxFF. We show that it is very accurate as compared to the DFT reference results for a wide range of properties, including low energy bulk phases, liquid structure, as well as point, line, and plane defects in the diamond structure.

Deuteron stripping reactions with Tabakin potential

International Nuclear Information System (INIS)

Osman, A.

1976-05-01

Deuteron stripping reactions are considered. Due to the strong repulsion between nucleons at very short distances, we have investigated the nuclear short-range correlations. The neutron proton nuclear potential in the deuteron is taken as a short-range repulsive core surrounded by a long-range attractive potential. The neutron-proton potential is taken as the Tabakin separable potential to take into account the short-range correlations. The differential cross-sections for deuteron stripping reactions have been calculated in two different cases by taking Yamaguchi or Breit et al type parameters for the Tabakin potential used. The angular distributions for different (d,p) stripping reactions on the different target nuclei 28 Si, 32 , 34 S, 36 Ar, 40 , 48 Ca, 50 , 52 , 54 Cr have been calculated using the DWBA calculations. Our present theoretical calculations for the angular distributions of the different reactions cosidered have been fitted to the experimental data, where good agreement is obtained. The extracted spectroscopic factors from the present work are found to be more reliable

Testing an excited-state energy density functional and the associated potential with the ionization potential theorem

International Nuclear Information System (INIS)

Hemanadhan, M; Shamim, Md; Harbola, Manoj K

2014-01-01

The modified local spin density (MLSD) functional and the related local potential for excited states is tested by employing the ionization potential theorem. The exchange functional for an excited state is constructed by splitting k-space. Since its functional derivative cannot be obtained easily, the corresponding exchange potential is given by an analogy to its ground-state counterpart. Further, to calculate the highest occupied orbital energy ϵ max accurately, the potential is corrected for its asymptotic behaviour by employing the van Leeuwen and Baerends (LB) correction to it. ϵ max so obtained is then compared with the ΔSCF ionization energy calculated using the MLSD functional with self-interaction correction for the orbitals involved in the transition. It is shown that the two match quite accurately. The match becomes even better by tuning the LB correction with respect to a parameter in it. (paper)

Global warming potential of pavements

Energy Technology Data Exchange (ETDEWEB)

Santero, Nicholas J [Department of Civil and Environmental Engineering, 407 McLaughlin Hall, University of California, Berkeley, CA 94720-1712 (United States); Horvath, Arpad, E-mail: njsantero@cal.berkeley.ed, E-mail: horvath@ce.berkeley.ed [Department of Civil and Environmental Engineering, 215B McLaughlin Hall, University of California, Berkeley, CA 94720-1712 (United States)

2009-09-15

Pavements comprise an essential and vast infrastructure system supporting our transportation network, yet their impact on the environment is largely unquantified. Previous life-cycle assessments have only included a limited number of the applicable life-cycle components in their analysis. This research expands the current view to include eight different components: materials extraction and production, transportation, onsite equipment, traffic delay, carbonation, lighting, albedo, and rolling resistance. Using global warming potential as the environmental indicator, ranges of potential impact for each component are calculated and compared based on the information uncovered in the existing research. The relative impacts between components are found to be orders of magnitude different in some cases. Context-related factors, such as traffic level and location, are also important elements affecting the impacts of a given component. A strategic method for lowering the global warming potential of a pavement is developed based on the concept that environmental performance is improved most effectively by focusing on components with high impact potentials. This system takes advantage of the fact that small changes in high-impact components will have more effect than large changes in low-impact components.

Global warming potential of pavements

International Nuclear Information System (INIS)

Santero, Nicholas J; Horvath, Arpad

2009-01-01

Pavements comprise an essential and vast infrastructure system supporting our transportation network, yet their impact on the environment is largely unquantified. Previous life-cycle assessments have only included a limited number of the applicable life-cycle components in their analysis. This research expands the current view to include eight different components: materials extraction and production, transportation, onsite equipment, traffic delay, carbonation, lighting, albedo, and rolling resistance. Using global warming potential as the environmental indicator, ranges of potential impact for each component are calculated and compared based on the information uncovered in the existing research. The relative impacts between components are found to be orders of magnitude different in some cases. Context-related factors, such as traffic level and location, are also important elements affecting the impacts of a given component. A strategic method for lowering the global warming potential of a pavement is developed based on the concept that environmental performance is improved most effectively by focusing on components with high impact potentials. This system takes advantage of the fact that small changes in high-impact components will have more effect than large changes in low-impact components.

Potential theory for directed networks.

Directory of Open Access Journals (Sweden)

Qian-Ming Zhang

Full Text Available Uncovering factors underlying the network formation is a long-standing challenge for data mining and network analysis. In particular, the microscopic organizing principles of directed networks are less understood than those of undirected networks. This article proposes a hypothesis named potential theory, which assumes that every directed link corresponds to a decrease of a unit potential and subgraphs with definable potential values for all nodes are preferred. Combining the potential theory with the clustering and homophily mechanisms, it is deduced that the Bi-fan structure consisting of 4 nodes and 4 directed links is the most favored local structure in directed networks. Our hypothesis receives strongly positive supports from extensive experiments on 15 directed networks drawn from disparate fields, as indicated by the most accurate and robust performance of Bi-fan predictor within the link prediction framework. In summary, our main contribution is twofold: (i We propose a new mechanism for the local organization of directed networks; (ii We design the corresponding link prediction algorithm, which can not only testify our hypothesis, but also find out direct applications in missing link prediction and friendship recommendation.

Potential Theory for Directed Networks

Science.gov (United States)

Zhang, Qian-Ming; Lü, Linyuan; Wang, Wen-Qiang; Zhou, Tao

2013-01-01

Uncovering factors underlying the network formation is a long-standing challenge for data mining and network analysis. In particular, the microscopic organizing principles of directed networks are less understood than those of undirected networks. This article proposes a hypothesis named potential theory, which assumes that every directed link corresponds to a decrease of a unit potential and subgraphs with definable potential values for all nodes are preferred. Combining the potential theory with the clustering and homophily mechanisms, it is deduced that the Bi-fan structure consisting of 4 nodes and 4 directed links is the most favored local structure in directed networks. Our hypothesis receives strongly positive supports from extensive experiments on 15 directed networks drawn from disparate fields, as indicated by the most accurate and robust performance of Bi-fan predictor within the link prediction framework. In summary, our main contribution is twofold: (i) We propose a new mechanism for the local organization of directed networks; (ii) We design the corresponding link prediction algorithm, which can not only testify our hypothesis, but also find out direct applications in missing link prediction and friendship recommendation. PMID:23408979

Hydrogen utilization potential in subsurface sediments

Directory of Open Access Journals (Sweden)

Rishi Ram Adhikari

2016-01-01

Full Text Available Subsurface microbial communities undertake many terminal electron-accepting processes, often simultaneously. Using a tritium-based assay, we measured the potential hydrogen oxidation catalyzed by hydrogenase enzymes in several subsurface sedimentary environments (Lake Van, Barents Sea, Equatorial Pacific and Gulf of Mexico with different predominant electron-acceptors. Hydrogenases constitute a diverse family of enzymes expressed by microorganisms that utilize molecular hydrogen as a metabolic substrate, product or intermediate. The assay reveals the potential for utilizing molecular hydrogen and allows qualitative detection of microbial activity irrespective of the predominant electron-accepting process. Because the method only requires samples frozen immediately after recovery, the assay can be used for identifying microbial activity in subsurface ecosystems without the need to preserve live material.We measured potential hydrogen oxidation rates in all samples from multiple depths at several sites that collectively span a wide range of environmental conditions and biogeochemical zones. Potential activity normalized to total cell abundance ranges over five orders of magnitude and varies, dependent upon the predominant terminal electron acceptor. Lowest per-cell potential rates characterize the zone of nitrate reduction and highest per-cell potential rates occur in the methanogenic zone. Possible reasons for this relationship to predominant electron acceptor include (i increasing importance of fermentation in successively deeper biogeochemical zones and (ii adaptation of H2ases to successively higher concentrations of H2 in successively deeper zones.

Time-dependent potential-functional embedding theory

International Nuclear Information System (INIS)

Huang, Chen; Libisch, Florian; Peng, Qing; Carter, Emily A.

2014-01-01

We introduce a time-dependent potential-functional embedding theory (TD-PFET), in which atoms are grouped into subsystems. In TD-PFET, subsystems can be propagated by different suitable time-dependent quantum mechanical methods and their interactions can be treated in a seamless, first-principles manner. TD-PFET is formulated based on the time-dependent quantum mechanics variational principle. The action of the total quantum system is written as a functional of the time-dependent embedding potential, i.e., a potential-functional formulation. By exploiting the Runge-Gross theorem, we prove the uniqueness of the time-dependent embedding potential under the constraint that all subsystems share a common embedding potential. We derive the integral equation that such an embedding potential needs to satisfy. As proof-of-principle, we demonstrate TD-PFET for a Na 4 cluster, in which each Na atom is treated as one subsystem and propagated by time-dependent Kohn-Sham density functional theory (TDDFT) using the adiabatic local density approximation (ALDA). Our results agree well with a direct TDDFT calculation on the whole Na 4 cluster using ALDA. We envision that TD-PFET will ultimately be useful for studying ultrafast quantum dynamics in condensed matter, where key regions are solved by highly accurate time-dependent quantum mechanics methods, and unimportant regions are solved by faster, less accurate methods

Corrosion potential detection method, potential characteristic simulation method for reaction rate and plant monitoring system using the same

International Nuclear Information System (INIS)

Sakai, Masanori; Onaka, Noriyuki; Takahashi, Tatsuya; Yamanaka, Hiroshi.

1995-01-01

In a calculation controlling device for a plant monitoring system, concentrations of materials concerning reaction materials in a certain state of a reaction process, and an actually measured value for the potential of a material in this state are substituted into a reaction rate equation obtained in accordance with a reaction process model. With such procedures, a relation between the reaction rate (current value) and the potential of the material can be obtained. A potential at which the reaction rates of an anode reaction and a cathode reaction contained in a corrosion reaction are made equal is determined by a numerical value calculation, based on an electrochemical hybrid potential logic by using the reaction rate equation, the reaction rate information relative to the corrosion reaction of the material and the concentration of the material concerning the corrosion reaction is obtained by a numerical value calculation. Then, simulation for the corrosion potential is enabled based on the handling corresponding to the actual reaction. Further, even for a portion which can not be measured actually, the corrosion potential can be recognized by simulation. (N.H.)

Nucleus-nucleus potential with repulsive core and elastic scattering. Part 1. Nucleus-nucleus interaction potential

International Nuclear Information System (INIS)

Davidovs'ka, O.Yi.; Denisov, V.Yu.; Nesterov, V.O.

2010-01-01

Various approaches for nucleus-nucleus interaction potential evaluation are discussed in details. It is shown that the antisymmetrization of nucleons belonging to different nuclei and the Pauli principle give the essential contribution into the nucleus-nucleus potential at distances, when nuclei are strongly overlapping, and lead to appearance of the repulsive core of nucleus nucleus interaction at small distances between nuclei.

Sicilian potential biogas production

Directory of Open Access Journals (Sweden)

Antonio Comparetti

2013-09-01

Full Text Available This study is aimed at predicting the Sicilian potential biogas production, using the Organic Fraction of Municipal Solid Waste (OFMSW, animal manure and food industry by-products, in a region where only one biogas plant using MSW and one co-digestion plant are nowadays available. The statistical data about OFMSW, the number of animals bred in medium and large farms and the amounts of by-products of food processing industries were evaluated, in order to compute the Sicilian potential biogas and energy production. The OFMSW produced in Sicily, that is 0.8 million tons ca. per year (37% of MSW, could be used in a bio-reactor, together with other raw materials, for Anaerobic Digestion (AD process, producing biogas and “digestate”. Moreover, 3.03 million tons ca. of manure, collected in medium and large animal husbandry farms (where cows, pigs and poultry are bred, and 350 thousand tons ca. of by-products, collected in food processing industries (pomace from olive oil mills and grape marc from wineries, might be used for AD process. The Sicilian potential biogas production from the AD of the above raw materials is 170.2 millions of m3, that is equal to 1023.4 GWh of energy per year, of which 484 GWh from animal manure, 303 GWh from OFMSW and 236.4 GWh from food industry by-products. The highest biogas production is in the province of Palermo (35.6 millions of m3, Ragusa (30.8 millions of m3 and Catania (22.8 millions of m3, having a potential energy production of 213.8, 185 and 137 GWh, respectively.

Supersymmetric quantum mechanics and new potentials

International Nuclear Information System (INIS)

Drigo Filho, E.

1988-01-01

Using the supersymmetric quantum mechanics the following potential are generalized. The particle in the box, Poeschl-Teller and Rosen-Morse. The new potentials are evaluated and their eigenfunctions and spectra are indicated. (author) [pt

Estimation of Radiative Efficiency of Chemicals with Potentially Significant Global Warming Potential

Data.gov (United States)

U.S. Environmental Protection Agency — The set of commercially available chemical substances in commerce that may have significant global warming potential (GWP) is not well defined. Although there are...

Phenomenological dirac optical potential for neutron cross sections

Energy Technology Data Exchange (ETDEWEB)

Maruyama, Shin-ichi; Kitsuki, Hirohiko; Shigyo, Nobuhiro; Ishibashi, Kenji [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering

1997-03-01

Because of limitation on neutron-incident data, it is difficult to obtain global optical model potential for neutrons. In contrast, there are some global optical model potentials for proton in detail. It is interesting to convert the proton-incident global optical potentials into neutron-incident ones. In this study we introduce (N-Z)/A dependent symmetry potential terms into the global proton-incident optical potentials, and then obtain neutron-incident ones. The neutron potentials reproduce total cross sections in an acceptable degree. However, a comparison with potentials proposed by other authors brings about a confused situation in the sign of the symmetry terms. (author)