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Sample records for artificial disc activ

  1. The activArtificial Disc: a next-generation motion-preserving implant for chronic lumbar discogenic pain

    PubMed Central

    Yue, James J; Garcia, Rolando; Miller, Larry E

    2016-01-01

    Degeneration of the lumbar intervertebral discs is a leading cause of chronic low back pain in adults. Treatment options for patients with chronic lumbar discogenic pain unresponsive to conservative management include total disc replacement (TDR) or lumbar fusion. Until recently, only two lumbar TDRs had been approved by the US Food and Drug Administration − the Charité Artificial Disc in 2004 and the ProDisc-L Total Disc Replacement in 2006. In June 2015, a next-generation lumbar TDR received Food and Drug Administration approval − the activArtificial Disc (Aesculap Implant Systems). Compared to previous-generation lumbar TDRs, the activArtificial Disc incorporates specific design enhancements that result in a more precise anatomical match and allow a range of motion that better mimics the healthy spine. The results of mechanical and clinical studies demonstrate that the activArtificial Disc results in improved mechanical and clinical outcomes versus earlier-generation artificial discs and compares favorably to lumbar fusion. The purpose of this report is to describe the activArtificial Disc including implant characteristics, intended use, surgical technique, postoperative care, mechanical testing, and clinical experience to date. PMID:27274317

  2. Artificial Disc Replacement

    MedlinePlus

    ... treat this condition, alternatives to disc replacement include fusion, nonoperative care or no treatment. Typically, surgery is ... operative treatment for disc pain has been spinal fusion. This is a surgical procedure in which disc ...

  3. The ProDisc artificial disc: insertion technique.

    PubMed

    Aryan, Henry E; Acosta, Frank L; Ames, Christopher P

    2005-10-01

    The ProDisc artificial lumbar disc was designed for use in treatment of degenerative lumbar disease. The disc is implanted using an anterior approach to the lumbar spine with the assistance of intraoperative fluoroscopy. A variety of insertion instruments guide the surgeon through this process. The disc is implanted via an anterior approach, generally retroperitoneally but on occasion transperitoneally. The different approaches and insertion technique are described in this article. PMID:16326288

  4. Biomechanical Study of Lumbar Spinal Arthroplasty with a Semi-Constrained Artificial Disc (Activ L) in the Human Cadaveric Spine

    PubMed Central

    Ha, Sung-Kon; Kim, Daniel H.; Park, Jung-Yul; Lim, Dong-Jun; Lee, Sang-Kook

    2009-01-01

    Objective The goal of this study was to evaluate the biomechanical features of human cadaveric spines implanted with the Activ L prosthesis. Methods Five cadaveric human lumbosacral spines (L2-S2) were tested for different motion modes, i.e. extension and flexion, right and left lateral bending and rotation. Baseline measurements of the range of motion (ROM), disc pressure (DP), and facet strain (FS) were performed in six modes of motion by applying loads up to 8 Nm, with a loading rate of 0.3 Nm/second. A constant 400 N axial follower preload was applied throughout the loading. After the Activ L was implanted at the L4-L5 disc space, measurements were repeated in the same manner. Results The Activ L arthroplasty showed statistically significant decrease of ROM during rotation, increase of ROM during flexion and lateral bending at the operative segment and increase of ROM at the inferior segment during flexion. The DP of the superior disc of the operative site was comparable to those of intact spine and the DP of the inferior disc decreased in all motion modes, but these were not statistically significant. For FS, statistically significant decrease was detected at the operative facet during flexion and at the inferior facet during rotation. Conclusion In vitro physiologic preload setting, the Activ L arthroplasty showed less restoration of ROM at the operative and adjacent levels as compared with intact spine. However, results of this study revealed that there are several possible theoretical useful results to reduce the incidence of adjacent segment disease. PMID:19352479

  5. Revision of a Charité artificial disc 9.5 years in vivo to a new Charité artificial disc: case report and explant analysis.

    PubMed

    David, Thierry

    2005-06-01

    This report describes a case of one-level total disc replacement (TDR) of L5-S1 requiring revision at 9.5 years following the index surgery due to polyethylene failure caused by high oxidation. Primary revision strategies for TDR include instrumented posterolateral fusion, or 360 degrees fusion with replacement of the prosthesis with cages or allograft bone. A revision of a TDR with a similar prosthesis has not been described in the literature. An active 42-year-old female underwent TDR with a Charité artificial disc. She remained active and pain free for 9.5 years before presenting with moderate low-back pain and sciatica. Radiographic studies confirmed a fragmented polyethylene core. The failed prosthesis was revised to a new Charité disc with the patient again active and pain free for 6 months following surgery. Chemical and physical analysis of the core indicated high oxidation due to gamma sterilization in air; a process changed to gamma sterilization in nitrogen in 1998 to meet industry standards. No evidence of wear debris was noted. Revision of an artificial disc with an artificial disc can be performed safely and adequately with the Charité disc prosthesis as an alternative to fusion necessitated by a device failure. An anterior revision approach carries significant risk and should only be performed by surgeons experienced in anterior lumbar surgery. PMID:15672241

  6. ISASS Policy Statement – Cervical Artificial Disc

    PubMed Central

    2014-01-01

    Morgan Lorio, MD, FACS, Chair, ISASS Task Force on Coding & Reimbursement The ISASS Task Force reached out to Domagoj Coric, MD to provide a timely summation on cervical disc arthroplasty given his special interest and recent IASP championship of this innovative technology to insure enhanced spine patient access. The ISASS Task Force is pleased with this step towards published ISASS societal policy and applauds Dr. Coric's effort; if ISASS is to continue to succeed we must continually harness the voluntary talents and energies of our members with gratitude. PMID:25694944

  7. ISASS Policy Statement – Lumbar Artificial Disc

    PubMed Central

    Garcia, Rolando

    2015-01-01

    Purpose The primary goal of this Policy Statement is to educate patients, physicians, medical providers, reviewers, adjustors, case managers, insurers, and all others involved or affected by insurance coverage decisions regarding lumbar disc replacement surgery. Procedures This Policy Statement was developed by a panel of physicians selected by the Board of Directors of ISASS for their expertise and experience with lumbar TDR. The panel's recommendation was entirely based on the best evidence-based scientific research available regarding the safety and effectiveness of lumbar TDR. PMID:25785243

  8. Disc Golf: Teaching a Lifetime Activity

    ERIC Educational Resources Information Center

    Eastham, Susan L.

    2015-01-01

    Disc golf is a lifetime activity that can be enjoyed by students of varying skill levels and abilities. Disc golf follows the principles of ball golf but is generally easier for students to play and enjoy success. The object of disc golf is similar to ball golf and involves throwing a disc from the teeing area to the target in as few throws as…

  9. Artificial Discs for Lumbar and Cervical Degenerative Disc Disease –Update

    PubMed Central

    2006-01-01

    Executive Summary Objective To assess the safety and efficacy of artificial disc replacement (ADR) technology for degenerative disc disease (DDD). Clinical Need Degenerative disc disease is the term used to describe the deterioration of 1 or more intervertebral discs of the spine. The prevalence of DDD is roughly described in proportion to age such that 40% of people aged 40 years have DDD, increasing to 80% among those aged 80 years or older. Low back pain is a common symptom of lumbar DDD; neck and arm pain are common symptoms of cervical DDD. Nonsurgical treatments can be used to relieve pain and minimize disability associated with DDD. However, it is estimated that about 10% to 20% of people with lumbar DDD and up to 30% with cervical DDD will be unresponsive to nonsurgical treatments. In these cases, surgical treatment is considered. Spinal fusion (arthrodesis) is the process of fusing or joining 2 bones and is considered the surgical gold standard for DDD. Artificial disc replacement is the replacement of the degenerated intervertebral disc with an artificial disc in people with DDD of the lumbar or cervical spine that has been unresponsive to nonsurgical treatments for at least 6 months. Unlike spinal fusion, ADR preserves movement of the spine, which is thought to reduce or prevent the development of adjacent segment degeneration. Additionally, a bone graft is not required for ADR, and this alleviates complications, including bone graft donor site pain and pseudoarthrosis. It is estimated that about 5% of patients who require surgery for DDD will be candidates for ADR. Review Strategy The Medical Advisory Secretariat conducted a computerized search of the literature published between 2003 and September 2005 to answer the following questions: What is the effectiveness of ADR in people with DDD of the lumbar or cervical regions of the spine compared with spinal fusion surgery? Does an artificial disc reduce the incidence of adjacent segment degeneration (ASD

  10. Activ C cervical disc replacement for myelopathy

    PubMed Central

    McGonagle, L.; Cadman, S.; Chitgopkar, S. D.; Canavan, L.; O’Malley, M.; Shackleford, I. M.

    2011-01-01

    Background: Cervical disc replacement is becoming an increasingly popular treatment option for cervical myelopathy. It retains motion at the affected segment, unlike anterior cervical discectomy and fusion. The aim of this study is to assess the outcomes of a series of patients who underwent Activ C disc replacement for cervical myelopathy. Materials and Methods: A series of patients at the above Trust with clinical and radiological evidence of cervical myelopathy who were suitable for cervical disc replacement from 2007 to 2009 were included. Implants were inserted by one of two consultant surgeons {IMS, MO’M}. Patients were assessed preoperatively and at six, 12 and 24 months, postoperatively, with a visual analogue score (VAS) for neck and arm pain severity and frequency, the Neck Disability Index questionnaire (NDI) and the Centre for Epidemiologic Studies Depression questionnaire (CES-D). Results: Ten patients underwent surgery between May 2007 and July 2009, 6 women, and 4 men. Average age was 54 years (40-64). Disc levels replaced were: four at C4-5; eight at C5-6; seven at C6-7. Three patients had one disc replaced, five patients had two discs replaced, and two patients had three discs replaced. The VAS for neck pain improved from 5.9 pre-operatively to 1.4-24 months postoperatively and the VAS arm pain improved from 5.4 to 2.6. The NDI improved from 51% preoperatively to 26.8% at 24 months postoperatively. The CES-D showed a slight increase from 19.5 preoperatively to 21.7 at 24 months, postoperatively. Conclusion: Cervical decompression and disc replacement improves pain and function in patients with cervical myelopathy. This benefit is maintained at 24 months post op, with no cases requiring revision. PMID:23125494

  11. Biomechanical effects of semi-constrained integrated artificial discs on zygapophysial joints of implanted lumbar segments

    PubMed Central

    ZHENG, SHENG-NAI; YAO, QING-QIANG; WANG, LI-MING; HU, WEN-HAO; WEI, BO; XU, YAN; ZHANG, DONG-SHENG

    2013-01-01

    This study aimed to optimize the design and application of semi-constrained integrated artificial discs (SIADs) using a finite element (FE) analysis following implantation, wherein the zygapophysial joints of the segment were biomechanically reconstructed. An FE model of the L4–L5 segment was constructed. Variations in the stresses on the discs and zygapophysial joints were observed during 5° anteflexion, 5° extension and 5° rotation under the 400-N applied axial load. Stresses and load translation analyses of the discs and zygapophysial joints were conducted during anteflexion, extension and rotation under the 400-N applied axial load. Following implantation of the lumbar segments, the stresses on the SIAD zygapophysial joints were not significantly different from those of physiological discs during anteflexion, and these were both marginally greater compared with those of non-constrained artificial discs (NADs). During extension, the increase in the stress on the SIAD zygapophysial joints was less than that on NAD zygapophysial joints. Stresses on the NAD zygapophysial joints were higher than those on SIAD and physiological discs during rotation. The stress on the SIAD zygapophysial joints was not significantly different from that on physiological discs during rotation. For SIADs and NADs, the stresses on the zygapophysial joints and the displacements of the discs were greater compared with those of the physiological discs during extension. The SIADs affected the variations in the stresses on the implanted segment more than the NADs, and the SIADs protected the zygapophysial joints of the implanted segment to a higher degree than the NADs. PMID:24255672

  12. Cervical artificial disc replacement with ProDisc-C: clinical and radiographic outcomes with long-term follow-up.

    PubMed

    Malham, Gregory M; Parker, Rhiannon M; Ellis, Ngaire J; Chan, Philip G; Varma, Dinesh

    2014-06-01

    Cervical artificial disc replacement (ADR) is indicated for the treatment of severe radiculopathy permitting neural decompression and maintenance of motion. We evaluated the clinical and radiographic outcomes in cervical ADR patients using the ProDisc-C device (DePuy Synthes, West Chester, PA, USA) with a 5-9 year follow-up. Data were collected through a prospective registry, with retrospective analysis performed on 24 consecutive patients treated with cervical ADR by a single surgeon. All patients underwent single- or two-level ADR with the ProDisc-C device. Outcome measures included neck and arm pain (visual analogue scale), disability (neck disability index [NDI]), complications and secondary surgery rates. Flexion-extension cervical radiographs were performed to assess range of motion (ROM) of the device and adjacent segment disease (ASD). Average follow-up was 7.7 years. Neck and arm pain improved 60% and 79%, respectively, and NDI had an improvement of 58%. There were no episodes of device migration or subsidence. Mean ROM of the device was 6.4°. Heterotopic ossification was present in seven patients (37%). Radiographic ASD below the device developed in four patients (21%) (one single-level and three two-level ADR). No patient required secondary surgery (repeat operations at the index level or adjacent levels). Fourteen out of 19 patients (74%) were able to return to employment, with a median return to work time of 1.3 months. The ProDisc-C device for cervical ADR is a safe option for patients providing excellent clinical outcomes, satisfactory return to work rates and maintenance of segmental motion despite radiographic evidence of heterotopic ossification and ASD on long-term follow-up. PMID:24417795

  13. Cervical Footprint Anthropometry in Indian Population: Implications on Design of Artificial Disc Replacement Devices

    PubMed Central

    Patil, Vishwanath Mahabaleshwar; Bangalore, Shashidhar Kantharajanna; Saraf, Abhishek

    2016-01-01

    Study Design Cross-sectional study. Purpose To accurately measure the dimensions of cervical endplates based on computed tomography (CT) scans in Indian population and assess accuracy of match with currently available cervical disc prostheses. Overview of Literature The dimensions of currently available cervical disc replacement implants are based on early published geometrical measurements of vertebrae endplates for Caucasian population. To author's knowledge, similar study has not been published for patients from Indian subcontinent. Methods CT scans of cervical spine of patients from Indian subcontinent were collected and reviewed. Seventy patients (54 men and 16 women; aged 18–56 years with average of 37 years) who underwent CT scans of cervical spine were included in study. 3D CT scans of sub axial cervical spine (C3 to C7) were analyzed. The anterior-posterior (AP) and central mediolateral (CML) dimensions of superior and inferior endplates from C3 to C7 were measured using digital measuring system. Results A total of 560 endplates of 70 patients were included in the study. The AP diameter of cervical endplates ranged from 0.87 to 2.47 cm. The CML diameters ranged from 0.84 to 2.98 cm. For levels C3/C4 and C4/C5 for AP dimension Prestige-LP (90.5%) and Prodisc-C (89%) discs showed higher percentage of matching than Discover discs (58.5%). For CML diameter, Prestige-LP (69.5%), Prodisc-C (70%) and Discover (39.5%) discs showed almost similar matching with measured endplates. For levels C5/C6 and C6/C7 for AP dimension, Prestige-LP (67.25%), Prodisc-C (49.35%) and Discover (51.5%) discs showed similar matching. For CML diameter Prestige-LP (32%), Prodisc-C (27.5%) and Discover (42.2%) discs showed poor matching with measured endplates. Conclusions This study indicates need for redesign of cervical disc prostheses to match Indian patients. The collected anthropometric dimensions from this study may be used to design and develop indigenous artificial total disc

  14. Long term preservation of motion with artificial cervical disc implants: A comparison between cervical disc replacement and rigid fusion with cage

    PubMed Central

    Cincu, Rafael; Lorente, Francisco de Asis; Gomez, Joaquin; Eiras, Jose; Agrawal, Amit

    2014-01-01

    Background: With the advancement of technologies there is more interest in the maintenance of the spine's biomechanical properties focusing on the preservation of the functional motion segment. In present article we describe our experience with 25 cases managed with artificial cervical discs with 28 Solis cage following cervical discectomy with a mean follow-up period of 7.5 year. Materials and Methods: All surgeries were performed by single surgeon from March 2004 to June 2005 with a follow-up till date. Patients with symptomatic single or multiple level diseases that had no prior cervical surgery were candidates for the study. Cohort demographics were comparable. Standardized clinical outcome measures and radiographic examinations were used at prescribed post-operative intervals to compare the treatment groups. Relief in radicular pain, cervical spine motion, and degenerative changes at follow-up were noted. Results: In a total 53 cases, the mean age in prosthesis group was 47 years (age range: 30-63 years) and mean age in cage group was 44 years (32-62 years). Mean hospital stay was 2.7 days in both the groups. At 4 weeks complete cervical movements could be achieved in 19 cases in artificial disc group. Maintenance of movement after 7.5 years was in 76% of these patients. Lordosis was maintained in all cases till date. There was no mortality or wound infection in our series. Conclusions: We conclude that artificial cervical disc could be an alternative to fixed spinal fusion as it represents the most physiological substitute of disc. However, there is need for further studies to support the use of artificial cervical disc prosthesis. PMID:25685218

  15. Biomechanics of Hybrid Anterior Cervical Fusion and Artificial Disc Replacement in 3-Level Constructs: An In Vitro Investigation

    PubMed Central

    Liao, Zhenhua; Fogel, Guy R.; Pu, Ting; Gu, Hongsheng; Liu, Weiqiang

    2015-01-01

    Background The ideal surgical approach for cervical disk disease remains controversial, especially for multilevel cervical disease. The purpose of this study was to investigate the biomechanics of the cervical spine after 3-level hybrid surgery compared with 3-level anterior cervical discectomy and fusion (ACDF). Material/Methods Eighteen human cadaveric spines (C2-T1) were evaluated under displacement-input protocol. After intact testing, a simulated hybrid construct or fusion construct was created between C3 to C6 and tested in the following 3 conditions: 3-level disc plate disc (3DPD), 3-level plate disc plate (3PDP), and 3-level plate (3P). Results Compared to intact, almost 65~80% of motion was successfully restricted at C3-C6 fusion levels (p<0.05). 3DPD construct resulted in slight increase at the 3 instrumented levels (p>0.05). 3PDP construct resulted in significant decrease of ROM at C3-C6 levels less than 3P (p<0.05). Both 3DPD and 3PDP caused significant reduction of ROM at the arthrodesis level and produced motion increase at the arthroplasty level. For adjacent levels, 3P resulted in markedly increased contribution of both upper and lower adjacent levels (p<0.05). Significant motion increases lower than 3P were only noted at partly adjacent levels in some conditions for 3DPD and 3PDP (p<0.05). Conclusions ACDF eliminated motion within the construct and greatly increased adjacent motion. Artificial cervical disc replacement normalized motion of its segment and adjacent segments. While hybrid conditions failed to restore normal motion within the construct, they significantly normalized motion in adjacent segments compared with the 3-level ACDF condition. The artificial disc in 3-level constructs has biomechanical advantages compared to fusion in normalizing motion. PMID:26529430

  16. Initial clinical experience with a next-generation artificial disc for the treatment of symptomatic degenerative cervical radiculopathy

    PubMed Central

    Reyes-Sanchez, Alejandro; Miramontes, Victor; Olivarez, Luis M. Rosales; Aquirre, Armando Alpizar; Quiroz, Alfredo Ortega; Zarate-Kalfopulos, Baron

    2010-01-01

    Background A feasibility trial was conducted to evaluate the initial safety and clinical use of a next-generation artificial cervical disc (M6-C artificial cervical disc; Spinal Kinetics, Sunnyvale, CA) for the treatment of patients with symptomatic degenerative cervical radiculopathy. A standardized battery of validated outcome measures was utilized to assess condition-specific functional impairment, pain severity, and quality of life. Methods Thirty-six consecutive patients were implanted with the M6-C disc and complete clinical and radiographic outcomes for 25 patients (mean age, 44.5 ± 10.1 years) with radiographically-confirmed cervical disc disease and symptomatic radiculopathy unresponsive to conservative medical management are included in this report. All patients had disc-osteophyte complex causing neural compression and were treated with discectomy and artificial cervical disc replacement at either single level (n = 12) or 2-levels (n = 13). Functional impairment was evaluated using the Neck Disability Index (NDI). Evaluation of arm and neck pain severity utilized a standard 11-point numeric scale, and health-related quality of life was evaluated with the SF-36 Health Survey. Quantitative radiographic assessments of intervertebral motion were performed using specialized motion analysis software, QMA (Quantitative Motion Analysis; Medical Metrics, Houston, TX). All outcome measures were evaluated pre-treatment and at 6 weeks, 3, 6, 12, and 24 months. Results The mean NDI score improved from 51.6 ± 11.3% pre-treatment to 27.9 ± 16.9% at 24 months, representing an approximate 46% improvement (P <.0001). The mean arm pain score improved from 6.9 ± 2.5 pre-treatment to 3.9 ± 3.1 at 24 months (43%, P =.0006). The mean neck pain score improved from 7.8 ± 2.0 pre-treatment to 3.8 ± 3.0 at 24 months (51%, P <.0001). The mean PCS score of the SF-36 improved from 34.8 ± 7.8 pre-treatment to 43.8 ± 9.3 by 24 months (26%, P =.0006). Subgroup analyses found

  17. Hybrid Strategy of Two-Level Cervical Artificial Disc and Intervertebral Cage: Biomechanical Effects on Tissues and Implants.

    PubMed

    Chung, Tzu-Tsao; Hueng, Dueng-Yuan; Lin, Shang-Chih

    2015-11-01

    This numerical study aimed to evaluate tissue and implant responses to the hybrid surgery (HS) of cervical artificial disc replacement (C-ADR) and anterior cervical discectomy and fusion (ACDF).Four hybrid strategies of two-level C-ADR and ACDF were compared in terms of adjacent segment degeneration (ASD) and implant failure.The rotary C-ADR and semirigid ACDF have been extensively used in the multilevel treatment of cervical instability and degeneration, but the constrained mobility at the ACDF segments can induce postoperative ASD problems. Hybrid surgery of C-ADR and ACDF has been an alternative to provide the optimal tradeoff between surgical cost and ASD problems. The biomechanical effects of hybrid strategies warrant thorough investigation for the two-level instrumentation.Based on computed tomography imaging, a nonlinear C2-C7 model was developed and validated by cadaveric and numerical data. Four strategies of inserting the C-ADR and ACDF into the C4-C6 segments were systematically arranged as PP (2 peek cages), AA (2 artificial discs), PA, and AP. The biomechanical behavior of these 4 strategies was evaluated in terms of motion and stresses of discs, facet forces, stresses of C-ADR and ACDF, and C-ADR motion.The constrained mobility of the ACDF segment worsened the kinematic and mechanical demands of the adjacent segments and artificial discs. The C-ADR articulation provided higher mobility than the replaced disc of the intact construct, making it an effective buffer to accommodate the compensated mobility and load from the ACDF segment. Consequently, the ASD progression of the AA construct was most restricted, followed by the PA, AP, and PP construct.The PA strategy is a tradeoff to preserve mobility and reduce cost. The C-ADR of the PA construct preserves the mobility of the C5/C6 segment and shares the transferred motion and loads of the fused C4/C5 segment. The PA construct shows optimal biomechanical results for minimizing ASD and implant failure

  18. Artificial disc and vertebra system: a novel motion preservation device for cervical spinal disease after vertebral corpectomy

    PubMed Central

    Dong, Jun; Lu, Meng; Lu, Teng; Liang, Baobao; Xu, Junkui; Qin, Jie; Cai, Xuan; Huang, Sihua; Wang, Dong; Li, Haopeng; He, Xijing

    2015-01-01

    OBJECTIVE: To determine the range of motion and stability of the human cadaveric cervical spine after the implantation of a novel artificial disc and vertebra system by comparing an intact group and a fusion group. METHODS: Biomechanical tests were conducted on 18 human cadaveric cervical specimens. The range of motion and the stability index range of motion were measured to study the function and stability of the artificial disc and vertebra system of the intact group compared with the fusion group. RESULTS: In all cases, the artificial disc and vertebra system maintained intervertebral motion and reestablished vertebral height at the operative level. After its implantation, there was no significant difference in the range of motion (ROM) of C3–7 in all directions in the non-fusion group compared with the intact group (p>0.05), but significant differences were detected in flexion, extension and axial rotation compared with the fusion group (p<0.05). The ROM of adjacent segments (C3−4, C6−7) of the non-fusion group decreased significantly in some directions compared with the fusion group (p<0.05). Significant differences in the C4-6 ROM in some directions were detected between the non-fusion group and the intact group. In the fusion group, the C4−6 ROM in all directions decreased significantly compared with the intact and non-fusion groups (p<0.01). The stability index ROM (SI-ROM) of some directions was negative in the non-fusion group, and a significant difference in SI-ROM was only found in the C4−6 segment of the non-fusion group compared with the fusion group. CONCLUSION: An artificial disc and vertebra system could restore vertebral height and preserve the dynamic function of the surgical area and could theoretically reduce the risk of adjacent segment degeneration compared with the anterior fusion procedure. However, our results should be considered with caution because of the low power of the study. The use of a larger sample should be considered

  19. Mechanically activated artificial cell by using microfluidics.

    PubMed

    Ho, Kenneth K Y; Lee, Lap Man; Liu, Allen P

    2016-01-01

    All living organisms sense mechanical forces. Engineering mechanosensitive artificial cell through bottom-up in vitro reconstitution offers a way to understand how mixtures of macromolecules assemble and organize into a complex system that responds to forces. We use stable double emulsion droplets (aqueous/oil/aqueous) to prototype mechanosensitive artificial cells. In order to demonstrate mechanosensation in artificial cells, we develop a novel microfluidic device that is capable of trapping double emulsions into designated chambers, followed by compression and aspiration in a parallel manner. The microfluidic device is fabricated using multilayer soft lithography technology, and consists of a control layer and a deformable flow channel. Deflections of the PDMS membrane above the main microfluidic flow channels and trapping chamber array are independently regulated pneumatically by two sets of integrated microfluidic valves. We successfully compress and aspirate the double emulsions, which result in transient increase and permanent decrease in oil thickness, respectively. Finally, we demonstrate the influx of calcium ions as a response of our mechanically activated artificial cell through thinning of oil. The development of a microfluidic device to mechanically activate artificial cells creates new opportunities in force-activated synthetic biology. PMID:27610921

  20. Artificial light and nocturnal activity in gammarids

    PubMed Central

    Hölker, Franz; Heller, Stefan; Berghahn, Rüdiger

    2014-01-01

    Artificial light is gaining attention as a potential stressor to aquatic ecosystems. Artificial lights located near streams increase light levels experienced by stream invertebrates and we hypothesized light would depress night drift rates. We also hypothesized that the effect of light on drift rates would decrease over time as the invertebrates acclimated to the new light level over the course of one month’s exposure. These hypotheses were tested by placing Gammarus spp. in eight, 75 m × 1 m artificial flumes. One flume was exposed to strong (416 lx) artificial light at night. This strong light created a gradient between 4.19 and 0.04 lx over the neighboring six artificial flumes, while a control flume was completely covered with black plastic at night. Night-time light measurements taken in the Berlin area confirm that half the flumes were at light levels experienced by urban aquatic invertebrates. Surprisingly, no light treatment affected gammarid drift rates. In contrast, physical activity measurements of in situ individually caged G. roeseli showed they increased short-term activity levels in nights of complete darkness and decreased activity levels in brightly lit flumes. Both nocturnal and diurnal drift increased, and day drift rates were unexpectadly higher than nocturnal drift. PMID:24688857

  1. Mechanically activated artificial cell by using microfluidics

    PubMed Central

    Ho, Kenneth K. Y.; Lee, Lap Man; Liu, Allen P.

    2016-01-01

    All living organisms sense mechanical forces. Engineering mechanosensitive artificial cell through bottom-up in vitro reconstitution offers a way to understand how mixtures of macromolecules assemble and organize into a complex system that responds to forces. We use stable double emulsion droplets (aqueous/oil/aqueous) to prototype mechanosensitive artificial cells. In order to demonstrate mechanosensation in artificial cells, we develop a novel microfluidic device that is capable of trapping double emulsions into designated chambers, followed by compression and aspiration in a parallel manner. The microfluidic device is fabricated using multilayer soft lithography technology, and consists of a control layer and a deformable flow channel. Deflections of the PDMS membrane above the main microfluidic flow channels and trapping chamber array are independently regulated pneumatically by two sets of integrated microfluidic valves. We successfully compress and aspirate the double emulsions, which result in transient increase and permanent decrease in oil thickness, respectively. Finally, we demonstrate the influx of calcium ions as a response of our mechanically activated artificial cell through thinning of oil. The development of a microfluidic device to mechanically activate artificial cells creates new opportunities in force-activated synthetic biology. PMID:27610921

  2. Biomechanics of Artificial Disc Replacements Adjacent to a 2-Level Fusion in 4-Level Hybrid Constructs: An In Vitro Investigation.

    PubMed

    Liao, Zhenhua; Fogel, Guy R; Wei, Na; Gu, Hongsheng; Liu, Weiqiang

    2015-01-01

    BACKGROUND The ideal procedure for multilevel cervical degenerative disc diseases remains controversial. Recent studies on hybrid surgery combining anterior cervical discectomy and fusion (ACDF) and artificial cervical disc replacement (ACDR) for 2-level and 3-level constructs have been reported in the literature. The purpose of this study was to estimate the biomechanics of 3 kinds of 4-level hybrid constructs, which are more likely to be used clinically compared to 4-level arthrodesis. MATERIAL AND METHODS Eighteen human cadaveric spines (C2-T1) were evaluated in different testing conditions: intact, with 3 kinds of 4-level hybrid constructs (hybrid C3-4 ACDR+C4-6 ACDF+C6-7ACDR; hybrid C3-5ACDF+C5-6ACDR+C6-7ACDR; hybrid C3-4ACDR+C4-5ACDR+C5-7ACDF); and 4-level fusion. RESULTS Four-level fusion resulted in significant decrease in the C3-C7 ROM compared with the intact spine. The 3 different 4-level hybrid treatment groups caused only slight change at the instrumented levels compared to intact except for flexion. At the adjacent levels, 4-level fusion resulted in significant increase of contribution of both upper and lower adjacent levels. However, for the 3 hybrid constructs, significant changes of motion increase far lower than 4P at adjacent levels were only noted in partial loading conditions. No destabilizing effect or hypermobility were observed in any 4-level hybrid construct. CONCLUSIONS Four-level fusion significantly eliminated motion within the construct and increased motion at the adjacent segments. For all 3 different 4-level hybrid constructs, ACDR normalized motion of the index segment and adjacent segments with no significant hypermobility. Compared with the 4-level ACDF condition, the artificial discs in 4-level hybrid constructs had biomechanical advantages compared to fusion in normalizing adjacent level motion. PMID:26694835

  3. Biomechanics of Artificial Disc Replacements Adjacent to a 2-Level Fusion in 4-Level Hybrid Constructs: An In Vitro Investigation

    PubMed Central

    Liao, Zhenhua; Fogel, Guy R.; Wei, Na; Gu, Hongsheng; Liu, Weiqiang

    2015-01-01

    Background The ideal procedure for multilevel cervical degenerative disc diseases remains controversial. Recent studies on hybrid surgery combining anterior cervical discectomy and fusion (ACDF) and artificial cervical disc replacement (ACDR) for 2-level and 3-level constructs have been reported in the literature. The purpose of this study was to estimate the biomechanics of 3 kinds of 4-level hybrid constructs, which are more likely to be used clinically compared to 4-level arthrodesis. Material/Methods Eighteen human cadaveric spines (C2–T1) were evaluated in different testing conditions: intact, with 3 kinds of 4-level hybrid constructs (hybrid C3–4 ACDR+C4–6 ACDF+C6–7ACDR; hybrid C3–5ACDF+C5–6ACDR+C6–7ACDR; hybrid C3–4ACDR+C4–5ACDR+C5–7ACDF); and 4-level fusion. Results Four-level fusion resulted in significant decrease in the C3–C7 ROM compared with the intact spine. The 3 different 4-level hybrid treatment groups caused only slight change at the instrumented levels compared to intact except for flexion. At the adjacent levels, 4-level fusion resulted in significant increase of contribution of both upper and lower adjacent levels. However, for the 3 hybrid constructs, significant changes of motion increase far lower than 4P at adjacent levels were only noted in partial loading conditions. No destabilizing effect or hypermobility were observed in any 4-level hybrid construct. Conclusions Four-level fusion significantly eliminated motion within the construct and increased motion at the adjacent segments. For all 3 different 4-level hybrid constructs, ACDR normalized motion of the index segment and adjacent segments with no significant hypermobility. Compared with the 4-level ACDF condition, the artificial discs in 4-level hybrid constructs had biomechanical advantages compared to fusion in normalizing adjacent level motion. PMID:26694835

  4. Clinical outcomes of single-level lumbar artificial disc replacement compared with transforaminal lumbar interbody fusion in an Asian population

    PubMed Central

    Lee, Wei Ting; Liu, Gabriel; Thambiah, Joseph; Wong, Hee Kit

    2015-01-01

    INTRODUCTION The objective of this study was to examine the clinical outcome of single-level lumbar artificial disc replacement (ADR) compared to that of transforaminal lumbar interbody fusion (TLIF) for the treatment of symptomatic degenerative disc disease (DDD) in an Asian population. METHODS This was a retrospective review of 74 patients who had surgery performed for discogenic lower backs that involved only the L4/5 and L5/S1 levels. All the patients had lumbar DDD without radiculopathy or spondylolithesis, and concordant pain with discogram at the pathological level. The patients were divided into two groups – those who underwent ADR and those who underwent TLIF. RESULTS A trend suggesting that the ADR group had better perioperative outcomes (less blood loss, shorter operating time, shorter hospital stay and shorter time to ambulation) than the TLIF group was observed. However, a trend indicating that surgical-approach-related complications occurred more frequently in the ADR group than the TLIF group was also observed. The rate of revision surgery was comparable between the two groups. CONCLUSION Our findings suggest that for the treatment of discogenic lower back pain, lumbar ADR has better perioperative outcomes and a similar revision rate when compared with TLIF. However, the use of ADR was associated with a higher incidence of surgical-approach-related complications. More studies with bigger cohort sizes and longer follow-up periods are needed to determine the long-term efficacy and safety of ADR in lumbar DDD. PMID:25917472

  5. Solar activity predicted with artificial intelligence

    NASA Astrophysics Data System (ADS)

    Lundstedt, Henrik

    The variability of solar activity has been described as a non-linear chaotic dynamic system. AI methods are therefore especially suitable for modelling and predicting solar activity. Many indicators of the solar activity have been used, such as sunspot numbers, F 10.7 cm solar radio flux, X-ray flux, and magnetic field data. Artificial neural networks have also been used by many authors to predict solar cycle activity. Such predictions will be discussed. A new attempt to predict the solar activity using SOHO/MDI high-time resolution solar magnetic field data is discussed. The purpose of this new attempt is to be able to predict episodic events and to predict occurrence of coronal mass ejections. These predictions will be a part of the Lund Space Weather Model.

  6. Wnt Signaling Activates Shh Signaling in Early Postnatal Intervertebral Discs, and Re-Activates Shh Signaling in Old Discs in the Mouse

    PubMed Central

    Sinner, Debora; Wylie, Christopher C.; Dahia, Chitra Lekha

    2014-01-01

    Intervertebral discs (IVDs) are strong fibrocartilaginous joints that connect adjacent vertebrae of the spine. As discs age they become prone to failure, with neurological consequences that are often severe. Surgical repair of discs treats the result of the disease, which affects as many as one in seven people, rather than its cause. An ideal solution would be to repair degenerating discs using the mechanisms of their normal differentiation. However, these mechanisms are poorly understood. Using the mouse as a model, we previously showed that Shh signaling produced by nucleus pulposus cells activates the expression of differentiation markers, and cell proliferation, in the postnatal IVD. In the present study, we show that canonical Wnt signaling is required for the expression of Shh signaling targets in the IVD. We also show that Shh and canonical Wnt signaling pathways are down-regulated in adult IVDs. Furthermore, this down-regulation is reversible, since re-activation of the Wnt or Shh pathways in older discs can re-activate molecular markers of the IVD that are lost with age. These data suggest that biological treatments targeting Wnt and Shh signaling pathways may be feasible as a therapeutic for degenerative disc disease. PMID:24892825

  7. Artificial oocyte activation: evidence for clinical readiness.

    PubMed

    Ebner, T; Montag, M

    2016-03-01

    Artificial oocyte activation using Ca(2+)ionophores or similar compounds is a widely applied technique in IVF laboratories. This is all the more interesting as most of the agents aiming for intracellular Ca(2+) increase do not result in physiological Ca(2+) oscillations but much rather cause a single Ca(2+) transient. Two observations from mammals may explain why a rather non-physiological single Ca(2+) peak caused by ionophores is sufficient to rescue cycles showing severe male factor infertility, deficient oocyte maturation, developmental problems in humans, or both. On the one hand, it has been shown that it is mainly the initial Ca(2+) rise that drives further downstream events, in particular calcium/calmodulin-dependent protein kinase II (CaMKII) action, and on the other, it is possible that this enzyme remains active even in the absence of Ca(2+). It therefore seems that mammalian oocytes can respond to a wide range of intracellular Ca(2+) signals and have a surprisingly high degree of tolerance for changes in cytosolic Ca(2+). As epigenetic consequences or differences in gene expression have not been studied to date, artificial oocyte activation has to be considered as experimental and should only be applied with a proper indication. PMID:26776820

  8. Crack orientation and depth estimation in a low-pressure turbine disc using a phased array ultrasonic transducer and an artificial neural network.

    PubMed

    Yang, Xiaoxia; Chen, Shili; Jin, Shijiu; Chang, Wenshuang

    2013-01-01

    Stress corrosion cracks (SCC) in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial neural network (ANN), is proposed to estimate both the depth and orientation of initial cracks in the turbine discs. Echo signals from cracks with different depths and orientations were collected by a phased array ultrasonic transducer, and the feature vectors were extracted by wavelet packet, fractal technology and peak amplitude methods. The radial basis function (RBF) neural network was investigated and used in this application. The final results demonstrated that the method presented was efficient in crack estimation tasks. PMID:24064602

  9. Crack Orientation and Depth Estimation in a Low-Pressure Turbine Disc Using a Phased Array Ultrasonic Transducer and an Artificial Neural Network

    PubMed Central

    Yang, Xiaoxia; Chen, Shili; Jin, Shijiu; Chang, Wenshuang

    2013-01-01

    Stress corrosion cracks (SCC) in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial neural network (ANN), is proposed to estimate both the depth and orientation of initial cracks in the turbine discs. Echo signals from cracks with different depths and orientations were collected by a phased array ultrasonic transducer, and the feature vectors were extracted by wavelet packet, fractal technology and peak amplitude methods. The radial basis function (RBF) neural network was investigated and used in this application. The final results demonstrated that the method presented was efficient in crack estimation tasks. PMID:24064602

  10. Comparison of wear behaviors for an artificial cervical disc under flexion/extension and axial rotation motions.

    PubMed

    Wang, Song; Song, Jian; Liao, Zhenhua; Feng, Pingfa; Liu, Weiqiang

    2016-06-01

    The wear behaviors of a ball-on-socket (UHMWPE-on-Ti6Al4V) artificial cervical disc were studied with 1.5MC (million cycles) wear simulation under single flexion/extension and axial rotation motion and their composite motion. The wear rates, wear traces, and contact stress were analyzed and contrasted based on mass loss, optical microscopy and SEM as well as 3D profilometer, and ANSYS software, respectively. A much higher wear rate and more severe wear scars appeared under multi-directional motion. Flexion/extension motion of 7.5° lead to more severe wear than that under axial rotation motion of 4°. The above results were closely related to the contact compression stress and shear stress. The wear surface in FE motion showed typical linear wear scratches while revealing obvious arc-shaped wear tracks in AR motion. However, the central zone of both ball and socket components revealed more severe wear tracks than that in the edge zone under these two different motions. The dominant wear mechanism was plowing/scratching and abrasive wear as well as a little oxidation wear for the titanium socket while it was scratching damage with adhesive wear and fatigue wear due to plastic deformation under cyclic load and motion profiles for the UHMWPE ball. PMID:27040218

  11. Conditional Activation of β-Catenin Signaling Leads to Severe Defects in Intervertebral Disc Tissue

    PubMed Central

    Wang, Meina; Tang, Dezhi; Shu, Bing; Wang, Baoli; Jin, Hongting; Hao, Suyang; Dresser, Karen A.; Shen, Jie; Im, Hee-Jeong; Sampson, Erik R.; Rubery, Paul T.; Zuscik, Michael J.; Schwarz, Edward M.; O'Keefe, Regis J.; Wang, Yongjun; Chen, Di

    2013-01-01

    Objective The incidence of low back pain is extremely high and is often linked to intervertebral disc (IVD) degeneration. The mechanism of this disease is currently unknown. In this study, we have investigated the role of β-catenin signaling in IVD tissue function. Methods β-catenin protein levels were measured in disc samples derived from patients with disc degeneration and normal subjects by immunohistochemistry (IHC). To generate β-catenin conditional activation (cAct) mice, Col2a1-CreERT2 transgenic mice were bred with β-cateninfx(Ex3)/fx(Ex3) mice. Changes in disc tissue morphology and function were analyzed by micro-CT, histology and real-time PCR assays. Results We found that β-catenin protein was up-regulated in disc tissues from patients with disc degeneration. To assess the effects of increased β-catenin on disc tissue we generated β-catenin cAct mice. Overexpression of β-catenin in disc cells led to extensive osteophyte formation in 3- and 6-month-old β-catenin cAct mice which were associated with significant changes in the cells and extracellular matrix of disc tissues and growth plate. Gene expression analysis demonstrated that activation of β-catenin could enhance Runx2-dependent Mmp13 and Adamts5 expression. Moreover, genetic ablation of the Mmp13 or Adamts5 under β-catenin cAct background, or treatment of β-catenin cAct mice with a specific MMP13 inhibitor, ameliorated the mutant phenotype. Conclusions β-catenin signaling pathway plays a critical role in disc tissue function. PMID:22422036

  12. Quality of systematic reviews: an example of studies comparing artificial disc replacement with fusion in the cervical spine

    PubMed Central

    Tashani, Osama A.; El-Tumi, Hanan; Aneiba, Khaled

    2015-01-01

    Cervical artificial disc replacement (C-ADR) is now an alternative to anterior cervical discectomy and fusion (ACDF). Many studies have evaluated the efficacy of C-ADR compared with ACDF. This led to a series of systematic reviews and meta-analyses to evaluate the evidence of the superiority of one intervention against the other. The aim of the study presented here was to evaluate the quality of these reviews and meta-analyses. Medline via Ovid, Embase, and Cochrane Library were searched using the keywords: (total disk replacement, prosthesis, implantation, discectomy, and arthroplasty) AND (cervical vertebrae, cervical spine, and spine) AND (systematic reviews, reviews, and meta-analysis). Screening and data extraction were conducted by two reviewers independently. Two reviewers then assessed the quality of the selected reviews and meta-analysis using 11-item AMSTAR score which is a validated measurement tool to assess the methodological quality of systematic reviews. Screening of full reports of 46 relevant abstracts resulted in the selection of 15 systematic reviews and/or meta-analyses as eligible for this study. The two reviewers’ inter-rater agreement level was high as indicated by kappa of >0.72. The AMSTAR score of the reviews ranged from 3 to 11. Only one study (a Cochrane review) scored 100% (AMSTAR 11). Five studies scored below (AMSTAR 5) indicating low-quality reviews. The most significant drawbacks of reviews of a score below 5 were not using an extensive search strategy, failure to use the scientific quality of the included studies appropriately in formulating a conclusion, not assessing publication bias, and not reporting the excluded studies. With a significant exception of a Cochrane review, the methodological quality of systematic reviews evaluating the evidence of C-ADR versus ACDF has to be improved. PMID:26205640

  13. Cost Utility Analysis of the Cervical Artificial Disc vs Fusion for the Treatment of 2-Level Symptomatic Degenerative Disc Disease: 5-Year Follow-up

    PubMed Central

    Yang, Zhuo; Nunley, Pierce; Stone, Marcus B.; Lee, Darrin; Kim, Kee D.

    2016-01-01

    BACKGROUND: The cervical total disc replacement (cTDR) was developed to treat cervical degenerative disc disease while preserving motion. OBJECTIVE: Cost-effectiveness of this intervention was established by looking at 2-year follow-up, and this update reevaluates our analysis over 5 years. METHODS: Data were derived from a randomized trial of 330 patients. Data from the 12-Item Short Form Health Survey were transformed into utilities by using the SF-6D algorithm. Costs were calculated by extracting diagnosis-related group codes and then applying 2014 Medicare reimbursement rates. A Markov model evaluated quality-adjusted life years (QALYs) for both treatment groups. Univariate and multivariate sensitivity analyses were conducted to test the stability of the model. The model adopted both societal and health system perspectives and applied a 3% annual discount rate. RESULTS: The cTDR costs $1687 more than anterior cervical discectomy and fusion (ACDF) over 5 years. In contrast, cTDR had $34 377 less productivity loss compared with ACDF. There was a significant difference in the return-to-work rate (81.6% compared with 65.4% for cTDR and ACDF, respectively; P = .029). From a societal perspective, the incremental cost-effective ratio (ICER) for cTDR was −$165 103 per QALY. From a health system perspective, the ICER for cTDR was $8518 per QALY. In the sensitivity analysis, the ICER for cTDR remained below the US willingness-to-pay threshold of $50 000 per QALY in all scenarios (−$225 816 per QALY to $22 071 per QALY). CONCLUSION: This study is the first to report the comparative cost-effectiveness of cTDR vs ACDF for 2-level degenerative disc disease at 5 years. The authors conclude that, because of the negative ICER, cTDR is the dominant modality. ABBREVIATIONS: ACDF, anterior cervical discectomy and fusion AWP, average wholesale price CE, cost-effectiveness CEA, cost-effectiveness analysis CPT, Current Procedural Terminology cTDR, cervical total disc

  14. Artificial Syntactic Violations Activate Broca's Region

    ERIC Educational Resources Information Center

    Petersson, Karl Magnus; Forkstam, Christian; Ingvar, Martin

    2004-01-01

    In the present study, using event-related functional magnetic resonance imaging, we investigated a group of participants on a grammaticality classification task after they had been exposed to well-formed consonant strings generated from an artificial regular grammar. We used an implicit acquisition paradigm in which the participants were exposed…

  15. Construction of a tissue engineered intervertebral disc with high biological activity using an allogeneic intervertebral disc supplemented with transfected nucleus pulposus cells expressing exogenous dopamine beta-hydroxylase.

    PubMed

    Bai, M; Wang, Y H; Yin, H P; Li, S W

    2015-01-01

    This study addressed the in vitro construction and biological activity of tissue engineered intervertebral discs with exogenous human dopamine beta-hydroxylase (DBH) nucleus pulposus cells. pSNAV2.0-DBH expression plasmids were utilized to enhance the survival rates of intervertebral disc tissue cells. Various concentrations of transfected nucleus pulposus cells were injected into the discs, and DBH mRNA expression was determined using polymerase chain reaction amplification. Polysaccharide content and total collagen protein content in the engineered disc nucleus pulposus tissue were determined. The visible fluorescence intensities of the 1 x 10(5) and 1 x 10(6) groups vs the 1 x 10(4) group were significantly increased (P < 0.05); no significant difference was observed between the 1 x 10(5) and 1 x 10(6) groups (P > 0.05) at 7 days after injection. DBH mRNA expression could be detected in the all but the EGFP control group at 14 days culture. No significant difference was observed in the protein content between the 1 x 10(4) and the control groups at various times, while the protein content was significantly higher in the 1 x 10(5) vs the control and the 1 x 10(4) groups at 7-, 14-, and 21-day cultures. These results demonstrate that a tissue engineered intervertebral disc with high biological activity can be constructed by utilizing allogeneic intervertebral discs stored in liquid nitrogen and a 1 x 10(5) transfected nucleus pulposus cell complex with in vitro culture for 14 days. This model can be used in animal experiments to study the biological activity of the engineered discs. PMID:26400296

  16. Textured bearing surface in artificial joints to reduce macrophage activation

    NASA Astrophysics Data System (ADS)

    Nakanishi, Yoshitaka; Nishi, Naoki; Chikaura, Hiroto; Nakashima, Yuta; Miura, Hiromasa; Higaki, Hidehiko; Mizuta, Hiroshi; Iwamoto, Yukihide; Fujiwara, Yukio; Komohara, Yoshihiro; Takeya, Motohiro

    2015-12-01

    Micro slurry-jet erosion has been proposed as a precision machining technique for the bearing surfaces of artificial joints in order to reduce the total amount of polyethylene wear and to enlarge the size of the wear debris. The micro slurry-jet erosion method is a wet blasting technique which uses alumina particles as the abrasive medium along with compressed air and water to create an ideal surface. Pin-on-disc wear tests with multidirectional sliding motion on the textured surface of a \\text{Co}-\\text{Cr}-\\text{Mo} alloy counterface for polyethylene resulted in both a reduction of wear as well as enlargement of the polyethylene debris size. In this study, primary human peripheral blood mononuclear phagocytes were incubated with the debris, and it was elucidated that the wear debris generated on the textured surface regulated secretion of the proinflammatory cytokines IL-6 and TNF-α, indicating a reduction in the induced tissue reaction and joint loosening.

  17. Intrinsic disc emission and the soft X-ray excess in active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Done, Chris; Davis, S. W.; Jin, C.; Blaes, O.; Ward, M.

    2012-03-01

    Narrow-line Seyfert 1 (NLS1) galaxies have low-mass black holes and mass accretion rates close to (or exceeding) Eddington, so a standard blackbody accretion disc should peak in the extreme ultraviolet. However, the lack of true absorption opacity in the disc means that the emission is better approximated by a colour temperature corrected blackbody, and this colour temperature correction is large enough (˜2.4) that the bare disc emission from a zero spin black hole can extend into the soft X-ray bandpass. Part of the soft X-ray excess seen in these objects must be intrinsic emission from the disc unless the vertical structure is very different to that predicted. None the less, this is not the whole story even for the extreme NLS1 as the shape of the soft excess is much broader than predicted by a bare disc spectrum, indicating some Compton upscattering by warm, optically thick material. We associate this with the disc itself, so it must ultimately be powered by mass accretion. We build an energetically self-consistent model assuming that the emission thermalizes to a (colour temperature corrected) blackbody only at large radii. At smaller radii the gravitational energy is split between powering optically thick Comptonized disc emission (forming the soft X-ray excess) and an optically thin corona above the disc (forming the tail to higher energies). We show examples of this model fit to the extreme NLS1 RE J1034+396, and to the much lower Eddington fraction broad-line Seyfert 1 PG 1048+231. We use these to guide our fits and interpretations of three template spectra made from co-adding multiple sources to track out a sequence of active galactic nucleus (AGN) spectra as a function of L/LEdd. Both the individual objects and template spectra show the surprising result that the Compton upscattered soft X-ray excess decreases in importance with increasing L/LEdd. The strongest soft excesses are associated with low mass accretion rate AGN rather than being tied to some

  18. Artificial Swimmers Propelled by Acoustically Activated Flagella.

    PubMed

    Ahmed, Daniel; Baasch, Thierry; Jang, Bumjin; Pane, Salvador; Dual, Jürg; Nelson, Bradley J

    2016-08-10

    Recent studies have garnered considerable interest in the field of propulsion to maneuver micro- and nanosized objects. Acoustics provide an alternate and attractive method to generate propulsion. To date, most acoustic-based swimmers do not use structural resonances, and their motion is determined by a combination of bulk acoustic streaming and a standing-wave field. The resultant field is intrinsically dependent on the boundaries of their resonating chambers. Though acoustic based propulsion is appealing in biological contexts, existing swimmers are less efficient, especially when operating in vivo, since no predictable standing-wave can be established in a human body. Here we describe a new class of nanoswimmer propelled by the small-amplitude oscillation of a flagellum-like flexible tail in standing and, more importantly, in traveling acoustic waves. The artificial nanoswimmer, fabricated by multistep electrodeposition techniques, compromises a rigid bimetallic head and a flexible tail. During acoustic excitation of the nanoswimmer the tail structure oscillates, which leads to a large amplitude propulsion in traveling waves. FEM simulation results show that the structural resonances lead to high propulsive forces. PMID:27459382

  19. Wear studies on ZrO2-filled PEEK as coating bearing materials for artificial cervical discs of Ti6Al4V.

    PubMed

    Song, Jian; Liu, Yuhong; Liao, Zhenhua; Wang, Song; Tyagi, Rajnesh; Liu, Weiqiang

    2016-12-01

    Polyetheretherketone (PEEK) and its composite coatings are believed to be the potential candidates' bio-implant materials. However, these coatings have not yet been used on the surface of titanium-based orthopedics and joint products and very few investigations on the tribological characteristics could be found in the published literature till date. In this study, the wettabilities, composition and micro-hardness were characterized using contact angle measurement, scanning electron microscopy (SEM) and hardness tester. The tribological tests were conducted using a ball-on-disc contact pair under 25% newborn calf serum (NCS) lubricated condition. For comparison, bare Ti6Al4V was studied. The obtained results revealed that those PEEK/ZrO2 composite coatings could improve the tribological properties of Ti6Al4V significantly. Adhesive wear and mild abrasive wear might be the dominant wear and failure mechanisms for PEEK/ZrO2 composite coatings in NCS lubricated condition. After comprehensive evaluation in the present study, 5wt.% ZrO2 nanoparticles filled PEEK coating displayed the optimum tribological characteristics and could be taken as a potential candidate for the bearing material of artificial cervical disc. PMID:27612794

  20. Conformational activation of visual rhodopsin in native disc membranes.

    PubMed

    Malmerberg, Erik; M Bovee-Geurts, Petra H; Katona, Gergely; Deupi, Xavier; Arnlund, David; Wickstrand, Cecilia; Johansson, Linda C; Westenhoff, Sebastian; Nazarenko, Elena; Schertler, Gebhard F X; Menzel, Andreas; de Grip, Willem J; Neutze, Richard

    2015-03-10

    Rhodopsin is the G protein-coupled receptor (GPCR) that serves as a dim-light receptor for vision in vertebrates. We probed light-induced conformational changes in rhodopsin in its native membrane environment at room temperature using time-resolved wide-angle x-ray scattering. We observed a rapid conformational transition that is consistent with an outward tilt of the cytoplasmic portion of transmembrane helix 6 concomitant with an inward movement of the cytoplasmic portion of transmembrane helix 5. These movements were considerably larger than those reported from the basis of crystal structures of activated rhodopsin, implying that light activation of rhodopsin involves a more extended conformational change than was previously suggested. PMID:25759477

  1. Paraspinal muscle activation in accordance with mechanoreceptors in the intervertebral discs.

    PubMed

    Kim, Young Eun; Choi, Hae Won

    2013-02-01

    Paraspinal muscle forces were derived computationally based on the hypothesis that the intervertebral disc has a transducer function and the muscle is activated according to a sensor-driving control mechanism. A three-dimensional finite element model of the musculoskeletal system, which consisted of a detailed whole lumbar spine, pelvis, simplified trunk model, and muscles, was developed and combined with an optimization technique to calculate muscle forces in isometric forward flexed and erect standing postures. Minimization of deviations in the nucleus pressure and averaged tensile stress in the annulus fibers at five discs was used for muscle force calculations. The results indicated that all the muscles were properly activated to maintain posture and stabilize the lumbar spine. The nucleus pressure difference was decreased during the iterative calculations and its resulting value at the L4/L5 level was consistent with in vivo measurements. Muscle activation produced vertebra motion, which resulted in a relatively uniform stress distribution in the intervertebral discs. This can minimize the risk of injury at a specific level and increase the ability of the spine to sustain a load. PMID:23513985

  2. Electrical activation of artificial muscles containing polyacrylonitrile gel fibers.

    PubMed

    Schreyer, H B; Gebhart, N; Kim, K J; Shahinpoor, M

    2000-01-01

    Gel fibers made from polyacrylonitrile (PAN) are known to elongate and contract when immersed in caustic and acidic solutions, respectively. The amount of contraction for these pH-activated fibers is 50% or greater, and the strength of these fibers is shown to be comparable to that of human muscle. Despite these attributes, the need of strong acids and bases for actuation has limited the use of PAN gel fibers as linear actuators or artificial muscles. Increasing the conductivity by depositing platinum on the fibers or combining the fibers with graphite fibers has allowed for electrical activation of artificial muscles containing gel fibers when placed in an electrochemical cell. The electrolysis of water in such a cell produces hydrogen ions at an artificial muscle anode, thus locally decreasing the pH and causing the muscle to contract. Reversing the electric field allows the PAN muscle to elongate. A greater than 40% contraction in artificial muscle length in less than 10 min is observed when it is placed as an electrode in a 10 mM NaCl electrolyte solution and connected to a 10 V power supply. These results indicate potential in developing electrically activated PAN muscles and linear actuators, which would be much more applicable than chemically activated muscles. PMID:11710194

  3. Antiurolithiatic activity of Abelmoschus moschatus seed extracts against zinc disc implantation-induced urolithiasis in rats

    PubMed Central

    Pawar, Anil T.; Vyawahare, Niraj S.

    2016-01-01

    Background: The commonly used techniques for removing renal calculi are associated with the risk of acute renal injury and increase in stone recurrence which indicates an urgent need for alternate therapy. Objectives: The aim was to evaluate the antiurolithiatic activity of Abelmoschus moschatus seed extracts in rats. Materials and Methods: Urolithiasis was induced by surgical implantations of zinc disc in the urinary bladders of rats. Upon postsurgical recovery, different doses of chloroform (CAM) and methanolic (MAM) extracts of A. moschatus seeds (viz., 100, 200 and 400 mg/kg body weight) were administered to disc implanted rats for the period of 7 days by the oral route. Antiurolithiatic activity was evaluated by measuring various dimensions of stones and estimating levels of various biomarkers in serum and urine samples. Results: A significant decrease in urinary output was observed in disc implanted animals, which was prevented by the treatment with extracts. Supplementation with extracts caused significant improvement in glomerular filtration rate and urinary total protein excretion. The elevated levels of serum creatinine, uric acid, and blood urea nitrogen were also prevented by the extracts. The extracts significantly reduced deposition of calculi deposition around the implanted disc. This antiurolithiatic potential is observed at all doses (100, 200, and 400 mg/kg) of MAM, whereas only higher dose (400 mg/kg) of CAM showed significant antiurolithiatic potential. Conclusion: The extracts of A. moschatus seeds possessed significant antiurolithiatic activity. The possible mechanism underlying this effect is mediated collectively through diuretic, antioxidant, and free-radical scavenging effects of the plant. PMID:27057124

  4. A Bayesian framework for active artificial perception.

    PubMed

    Ferreira, João Filipe; Lobo, Jorge; Bessière, Pierre; Castelo-Branco, Miguel; Dias, Jorge

    2013-04-01

    In this paper, we present a Bayesian framework for the active multimodal perception of 3-D structure and motion. The design of this framework finds its inspiration in the role of the dorsal perceptual pathway of the human brain. Its composing models build upon a common egocentric spatial configuration that is naturally fitting for the integration of readings from multiple sensors using a Bayesian approach. In the process, we will contribute with efficient and robust probabilistic solutions for cyclopean geometry-based stereovision and auditory perception based only on binaural cues, modeled using a consistent formalization that allows their hierarchical use as building blocks for the multimodal sensor fusion framework. We will explicitly or implicitly address the most important challenges of sensor fusion using this framework, for vision, audition, and vestibular sensing. Moreover, interaction and navigation require maximal awareness of spatial surroundings, which, in turn, is obtained through active attentional and behavioral exploration of the environment. The computational models described in this paper will support the construction of a simultaneously flexible and powerful robotic implementation of multimodal active perception to be used in real-world applications, such as human-machine interaction or mobile robot navigation. PMID:23014760

  5. Contractile activity is required for Z-disc sarcomere maturation in vivo

    PubMed Central

    Geach, Timothy J; Hirst, Elizabeth MA; Zimmerman, Lyle B

    2015-01-01

    Sarcomere structure underpins structural integrity, signaling, and force transmission in the muscle. In embryos of the frog Xenopus tropicalis, muscle contraction begins even while sarcomerogenesis is ongoing. To determine whether contractile activity plays a role in sarcomere formation in vivo, chemical tools were used to block acto-myosin contraction in embryos of the frog X. tropicalis, and Z-disc assembly was characterized in the paralyzed dicky ticker mutant. Confocal and ultrastructure analysis of paralyzed embryos showed delayed Z-disc formation and defects in thick filament organization. These results suggest a previously undescribed role for contractility in sarcomere maturation in vivo. genesis 53:299–307, 2015. © 2015 The Authors. Genesis Published by Wiley Periodicals, Inc. PMID:25845369

  6. Sucrose activates human taste pathways differently from artificial sweetener.

    PubMed

    Frank, Guido K W; Oberndorfer, Tyson A; Simmons, Alan N; Paulus, Martin P; Fudge, Julie L; Yang, Tony T; Kaye, Walter H

    2008-02-15

    Animal models suggest that sucrose activates taste afferents differently than non-caloric sweeteners. Little information exists how artificial sweeteners engage central taste pathways in the human brain. We assessed sucrose and sucralose taste pleasantness across a concentration gradient in 12 healthy control women and applied 10% sucrose and matched sucralose during functional magnet resonance imaging. The results indicate that (1) both sucrose and sucralose activate functionally connected primary taste pathways; (2) taste pleasantness predicts left insula response; (3) sucrose elicits a stronger brain response in the anterior insula, frontal operculum, striatum and anterior cingulate, compared to sucralose; (4) only sucrose, but not sucralose, stimulation engages dopaminergic midbrain areas in relation to the behavioral pleasantness response. Thus, brain response distinguishes the caloric from the non-caloric sweetener, although the conscious mind could not. This could have important implications on how effective artificial sweeteners are in their ability to substitute sugar intake. PMID:18096409

  7. Are passive red spirals truly passive?. The current star formation activity of optically red disc galaxies

    NASA Astrophysics Data System (ADS)

    Cortese, L.

    2012-07-01

    We used GALEX ultraviolet and WISE 22 μm observations to investigate the current star formation activity of the optically red spirals recently identified as part of the Galaxy Zoo project. These galaxies were accurately selected from the Sloan Digital Sky Survey as pure discs with low or no current star formation activity, representing one of the best optically selected samples of candidate passive spirals. However, we show that these galaxies are not only still forming stars at a significant rate (≳1 M⊙ yr-1) but, more importantly, their star formation activity is not different from that of normal star-forming discs of the same stellar mass (M∗ ≳ 1010.2 M⊙). Indeed, these systems lie on the UV-optical blue sequence, even without any corrections for internal dust attenuation, and they follow the same specific star formation rate vs. stellar mass relation of star-forming galaxies. Our findings clearly show that at high stellar masses, optical colours do not allow to distinguish between actively star-forming and truly quiescent systems.

  8. Cervical anterior hybrid technique with bi-level Bryan artificial disc replacement and adjacent segment fusion for cervical myelopathy over three consecutive segments.

    PubMed

    Chen, Jiang; Xu, Lin; Jia, Yu-Song; Sun, Qi; Li, Jin-Yu; Zheng, Chen-Ying; Bai, Chun-Xiao; Yu, Qin-Sheng

    2016-05-01

    This study aimed to assess the preliminary clinical efficacy and feasibility of the hybrid technique for multilevel cervical myelopathy. Considering the many shortcomings of traditional treatment methods for multilevel cervical degenerative myelopathy, hybrid surgery (bi-level Bryan artificial disc [Medtronic Sofamor Danek, Memphis, TN, USA] replacement and anterior cervical discectomy and fusion) should be considered. Between March 2006 and November 2012, 108 patients (68 men and 40 women, average age 45years) underwent hybrid surgery. Based on the Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), and Odom's criteria, the clinical symptoms and neurological function before and after surgery were evaluated. Mean surgery duration was 90minutes, with average blood loss of 30mL. Mean follow-up duration was 36months. At the final follow-up, the mean JOA (± standard deviation) scores were significantly higher compared with preoperative values (15.08±1.47 versus 9.18±1.22; P<0.01); meanwhile, NDI values were markedly decreased (12.32±1.03 versus 42.68±1.83; P<0.01). Using Odom's criteria, the clinical outcomes were rated as excellent (76 patients), good (22 patients), fair (six patients), and poor (four patients). These findings indicate that the hybrid method provides an effective treatment for cervical myelopathy over three consecutive segments, ensuring a good clinical outcome. PMID:26758702

  9. Experimental Active Control of Automotive Disc Brake Rotor Squeal Using Dither

    NASA Astrophysics Data System (ADS)

    CUNEFARE, K. A.; GRAF, A. J.

    2002-02-01

    This paper presents an experimental investigation into the application of “dither” control for the active control and suppression of automobile disc brake squeal. Dither control is characterized by the application of a control effort at a frequency higher than the disturbance to be controlled. In the particular system considered here, a vibro-acoustic analysis of a disc brake system during squeal determined the acoustic squeal signature to be emanating from the brake rotor. This squeal was eliminated, and could even be prevented from occurring, through the application of a harmonic force with a frequency higher than the squeal frequency. The harmonic force was generated by a stack of piezoelectric elements placed within the brake's caliper piston. The harmonic force represented a small variation about the mean clamping force exerted by the brake upon the rotor. The high-frequency vibration in the brake system due to the action of the control system was not heard if an ultrasonic control frequency was used. More importantly, the active control system is shown to be able to prevent squeal from even occurring. This gives rise to a possible active control system integrated into the brake system of automobiles to prevent squeal.

  10. Asset Inequality and Economic Activity in Artificial Societies

    NASA Astrophysics Data System (ADS)

    Kikuchi, Toshiko

    In this paper, using multi-agent simulations, the effect asset inequality has on an artificial society is analyzed. It is shown that it is possible for a sustainable society to decrease in asset inequality and at the same time increase economic activity. In sustainable societies, the asset inequality increases as the consumption tax rate is raised, and in artificial societies where the tax rate is the same, inequality increases in the society in which agents with even small a surplus undertake unselfish actions. In sustainable societies which employ both income and consumption tax, an increase in asset inequalities leads to an increase economic activity. But, in sustainable societies which levy only the income tax, this result does not necessarily hold. These results show that if economic activity is increased in sustainable societies where the consumption tax rate is raised for the fiscal stability, an inequality expansion is an acceptable consequence. However, the sustainable society with the highest economic activity is realized when only the income tax is levied. In sustainable societies which levy only the income tax, it is possible to decrease inequality while simultaneously increasing economic activity.

  11. Finite element simulations of the active stress in the imaginal disc of the Drosophila Melanogaster.

    PubMed

    Pettinati, V; Ambrosi, D; Ciarletta, P; Pezzuto, S

    2016-09-01

    During the larval stages of development, the imaginal disc of Drosphila Melanogaster is composed by a monolayer of epithelial cells, which undergo a strain actively produced by the cells themselves. The well-organized collective contraction produces a stress field that seemingly has a double morphogenetic role: it orchestrates the cellular organization towards the macroscopic shape emergence while simultaneously providing a local information on the organ size. Here we perform numerical simulations of such a mechanical control on morphogenesis at a continuum level, using a three-dimensional finite model that accounts for the active cell contraction. The numerical model is able to reproduce the (few) known qualitative characteristics of the tensional patterns within the imaginal disc of the fruit fly. The computed stress components slightly deviate from planarity, thus confirming the previous theoretical assumptions of a nonlinear elastic analytical model, and enforcing the hypothesis that the spatial variation of the mechanical stress may act as a size regulating signal that locally scales with the global dimension of the domain. PMID:26765274

  12. Excessive Myosin Activity in Mbs Mutants Causes Photoreceptor Movement Out of the Drosophila Eye Disc Epithelium

    PubMed Central

    Lee, Arnold; Treisman, Jessica E.

    2004-01-01

    Neuronal cells must extend a motile growth cone while maintaining the cell body in its original position. In migrating cells, myosin contraction provides the driving force that pulls the rear of the cell toward the leading edge. We have characterized the function of myosin light chain phosphatase, which down-regulates myosin activity, in Drosophila photoreceptor neurons. Mutations in the gene encoding the myosin binding subunit of this enzyme cause photoreceptors to drop out of the eye disc epithelium and move toward and through the optic stalk. We show that this phenotype is due to excessive phosphorylation of the myosin regulatory light chain Spaghetti squash rather than another potential substrate, Moesin, and that it requires the nonmuscle myosin II heavy chain Zipper. Myosin binding subunit mutant cells continue to express apical epithelial markers and do not undergo ectopic apical constriction. In addition, mutant cells in the wing disc remain within the epithelium and differentiate abnormal wing hairs. We suggest that excessive myosin activity in photoreceptor neurons may pull the cell bodies toward the growth cones in a process resembling normal cell migration. PMID:15075368

  13. Severe Impingement of Lumbar Disc Replacements Increases the Functional Biological Activity of Polyethylene Wear Debris

    PubMed Central

    Baxter, Ryan M.; MacDonald, Daniel W.; Kurtz, Steven M.; Steinbeck, Marla J.

    2013-01-01

    Background: Wear, oxidation, and particularly rim impingement damage of ultra-high molecular weight polyethylene total disc replacement components have been observed following surgical revision. However, neither in vitro testing nor retrieval-based evidence has shown the effect(s) of impingement on the characteristics of polyethylene wear debris. Thus, we sought to determine (1) differences in polyethylene particle size, shape, number, or biological activity that correspond to mild or severe rim impingement and (2) in an analysis of all total disc replacements, regardless of impingement classification, whether there are correlations between the extent of regional damage and the characteristics of polyethylene wear debris. Methods: The extent of dome and rim damage was characterized for eleven retrieved polyethylene cores obtained at revision surgery after an average duration of implantation of 9.7 years (range, 4.6 to 16.1 years). Polyethylene wear debris was isolated from periprosthetic tissues with use of nitric acid and was imaged with use of environmental scanning electron microscopy. Subsequently, particle size, shape, number, biological activity, and chronic inflammation scores were determined. Results: Grouping of particles by size ranges that represented high biological relevance (<0.1 to 1-μm particles), intermediate biological relevance (1 to 10-μm particles), and low biological relevance (>10-μm particles) revealed an increased volume fraction of particles in the <0.1 to 1-μm and 1 to 10-μm size ranges in the mild-impingement cohort as compared with the severe-impingement cohort. The increased volume fractions resulted in a higher specific biological activity per unit particle volume in the mild-impingement cohort than in the severe-impingement cohort. However, functional biological activity, which is normalized by particle volume (mm3/g of tissue), was significantly higher in the severe-impingement cohort. This increase was due to a larger volume

  14. Chemotaxis of artificial microswimmers in active density waves

    NASA Astrophysics Data System (ADS)

    Geiseler, Alexander; Hänggi, Peter; Marchesoni, Fabio; Mulhern, Colm; Savel'ev, Sergey

    2016-07-01

    Living microorganisms are capable of a tactic response to external stimuli by swimming toward or away from the stimulus source; they do so by adapting their tactic signal transduction pathways to the environment. Their self-motility thus allows them to swim against a traveling tactic wave, whereas a simple fore-rear asymmetry argument would suggest the opposite. Their biomimetic counterpart, the artificial microswimmers, also propel themselves by harvesting kinetic energy from an active medium, but, in contrast, lack the adaptive capacity. Here we investigate the transport of artificial swimmers subject to traveling active waves and show, by means of analytical and numerical methods, that self-propelled particles can actually diffuse in either direction with respect to the wave, depending on its speed and waveform. Moreover, chiral swimmers, which move along spiraling trajectories, may diffuse preferably in a direction perpendicular to the active wave. Such a variety of tactic responses is explained by the modulation of the swimmer's diffusion inside traveling active pulses.

  15. Chemotaxis of artificial microswimmers in active density waves.

    PubMed

    Geiseler, Alexander; Hänggi, Peter; Marchesoni, Fabio; Mulhern, Colm; Savel'ev, Sergey

    2016-07-01

    Living microorganisms are capable of a tactic response to external stimuli by swimming toward or away from the stimulus source; they do so by adapting their tactic signal transduction pathways to the environment. Their self-motility thus allows them to swim against a traveling tactic wave, whereas a simple fore-rear asymmetry argument would suggest the opposite. Their biomimetic counterpart, the artificial microswimmers, also propel themselves by harvesting kinetic energy from an active medium, but, in contrast, lack the adaptive capacity. Here we investigate the transport of artificial swimmers subject to traveling active waves and show, by means of analytical and numerical methods, that self-propelled particles can actually diffuse in either direction with respect to the wave, depending on its speed and waveform. Moreover, chiral swimmers, which move along spiraling trajectories, may diffuse preferably in a direction perpendicular to the active wave. Such a variety of tactic responses is explained by the modulation of the swimmer's diffusion inside traveling active pulses. PMID:27575185

  16. Oestrogen and parathyroid hormone alleviate lumbar intervertebral disc degeneration in ovariectomized rats and enhance Wnt/β-catenin pathway activity

    PubMed Central

    Jia, Haobo; Ma, Jianxiong; Lv, Jianwei; Ma, Xinlong; Xu, Weiguo; Yang, Yang; Tian, Aixian; Wang, Ying; Sun, Lei; Xu, Liyan; Fu, Lin; Zhao, Jie

    2016-01-01

    To investigate the mitigation effect and mechanism of oestrogen and PTH on disc degeneration in rats after ovariectomy, as well as on Wnt/β-catenin pathway activity, thirty 3-month-old rats were ovariectomized and divided into three groups. Ten additional rats were used as controls. Eight weeks later, the rats were administered oestrogen or PTH for 12 weeks, and then discs were collected for tests. Results showed that nucleus pulposus cells in the Sham group were mostly notochord cells, while in the OVX group, cells gradually developed into chondrocyte-like cells. Oestrogen or PTH could partly recover the notochord cell number. After ovariectomy, the endplate roughened and endplate porosity decreased. After oestrogen or PTH treatment, the smoothness and porosity of endplate recovered. Compared with the Sham group, Aggrecan, Col2a and Wnt/β-catenin pathway expression in OVX group decreased, and either oestrogen or PTH treatment improved their expression. The biomechanical properties of intervertebral disc significantly changed after ovariectomy, and oestrogen or PTH treatment partly recovered them. Disc degeneration occurred with low oestrogen, and the underlying mechanisms involve nutrition supply disorders, cell type changes and decreased Wnt/β-catenin pathway activity. Oestrogen and PTH can retard disc degeneration in OVX rats and enhance Wnt/β-catenin pathway activity in nucleus pulposus. PMID:27279629

  17. Oestrogen and parathyroid hormone alleviate lumbar intervertebral disc degeneration in ovariectomized rats and enhance Wnt/β-catenin pathway activity.

    PubMed

    Jia, Haobo; Ma, Jianxiong; Lv, Jianwei; Ma, Xinlong; Xu, Weiguo; Yang, Yang; Tian, Aixian; Wang, Ying; Sun, Lei; Xu, Liyan; Fu, Lin; Zhao, Jie

    2016-01-01

    To investigate the mitigation effect and mechanism of oestrogen and PTH on disc degeneration in rats after ovariectomy, as well as on Wnt/β-catenin pathway activity, thirty 3-month-old rats were ovariectomized and divided into three groups. Ten additional rats were used as controls. Eight weeks later, the rats were administered oestrogen or PTH for 12 weeks, and then discs were collected for tests. Results showed that nucleus pulposus cells in the Sham group were mostly notochord cells, while in the OVX group, cells gradually developed into chondrocyte-like cells. Oestrogen or PTH could partly recover the notochord cell number. After ovariectomy, the endplate roughened and endplate porosity decreased. After oestrogen or PTH treatment, the smoothness and porosity of endplate recovered. Compared with the Sham group, Aggrecan, Col2a and Wnt/β-catenin pathway expression in OVX group decreased, and either oestrogen or PTH treatment improved their expression. The biomechanical properties of intervertebral disc significantly changed after ovariectomy, and oestrogen or PTH treatment partly recovered them. Disc degeneration occurred with low oestrogen, and the underlying mechanisms involve nutrition supply disorders, cell type changes and decreased Wnt/β-catenin pathway activity. Oestrogen and PTH can retard disc degeneration in OVX rats and enhance Wnt/β-catenin pathway activity in nucleus pulposus. PMID:27279629

  18. Impaired hippocampal activity at the goal zone on the place preference task in a DISC1 mouse model.

    PubMed

    Hayashi, Yuichiro; Sawa, Akira; Hikida, Takatoshi

    2016-05-01

    Learning deficit is a clinical feature of many mental disorders and is hypothesized to result from an inability to integrate information in neural systems. We showed that transgenic mice expressing a dominant-negative form of DISC1, a risk gene for neuropsychiatric disorders, exhibited impaired performance in a reward-place association task when combined with a mild isolation stress. CA1 cells in the mutant mice showed normal place cell properties, but their activity at the goal zone was diminished. This abnormality in hippocampal activity at the goal zone during the task may underlie the learning deficit observed in the DISC1 mutant mice. PMID:26497623

  19. Screening of Hyaluronic Acid-Poly(ethylene glycol) Composite Hydrogels to Support Intervertebral Disc Cell Biosynthesis using Artificial Neural Network Analysis

    PubMed Central

    Jeong, Claire G.; Francisco, Aubrey T.; Niu, Zhenbin; Mancino, Robert L; Craig, Stephen L.; Setton, Lori A.

    2014-01-01

    Hyaluronic acid (HA) poly(ethylene glycol) (PEG) composite hydrogels have been widely studied for both cell delivery and soft tissue regeneration applications. A very broad range of physical and biological properties have been engineered into HA-PEG hydrogels that may differentially affect cellular “outcomes” of survival, synthesis and metabolism. The objective of this study was to rapidly screen multiple HA-PEG composite hydrogel formulations for an effect on matrix synthesis and behaviors of nucleus pulposus (NP) and anulus fibrosus (AF) cells of the intervertebral disc (IVD). A secondary objective was to apply artificial neural network (ANN) analysis to identify relationships between HA-PEG composite hydrogel formulation parameters and biological outcome measures for each cell type of the IVD. Eight different hydrogels were developed from preparations of thiolated HA (HA-SH) and PEG vinylsulfone (PEG-VS) macromers, and used as substrates for NP and AF cell culture in vitro. Hydrogel mechanical properties ranged from 70-489 kPa depending on HA molecular weight, and measures of matrix synthesis, metabolite consumption and production, and cell morphology were obtained to study relationships to hydrogel parameters. Results showed that NP and AF cell numbers were highest upon the HA-PEG hydrogels formed from the lower molecular weight HA, with evidence of higher sGAG production also upon lower HA molecular weight composite gels. All cells formed more multi-cell clusters upon any HA-PEG composite hydrogel as compared to gelatin substrates. Formulations were clustered into neurons based largely on their HA molecular weight, with few effects of PEG molecular weight observed on any measured parameters. PMID:24859415

  20. Differential activation by cytokines of mitogen-activated protein kinases in bovine temporomandibular-joint disc cells.

    PubMed

    Landesberg, R; Takeuchi, E; Puzas, J E

    1999-01-01

    Temporomandibular disorders affect a significant proportion of the population. While their aetiology is not well defined, recent histological studies suggest that the majority are similar to the osteoarthritis seen in other joints. Inflammatory cytokines such as interleukin-1 and tumour necrosis factor-alpha appear to be important in the cascade of events leading to joint destruction in osteoarthritis. Here, cells from the disc of bovine temporomandibular joint were used to examine the response to various cytokines in vitro. Disc cells were stimulated with interleukin-1alpha, tumour necrosis factor-alpha, transforming growth factor-beta, platelet-derived growth factor, and basic fibroblast growth factor. Their effects were monitored by assessing the phosphorylation of selected signal-transduction intermediates using western blot. Mitogen-activated protein kinases (Erk 1, Erk 2) were rapidly phosphorylated by exposure to basic fibroblast growth factor, platelet-derived growth factor, and tumour necrosis factor-alpha, while interleukin-1alpha showed a weak response. Transforming growth factor-beta failed to activate these kinases. Examination of the effect of these cytokines on p38 (an intermediate in the stress-activated protein-kinase pathway) showed an increase in phosphorylated p38 when stimulated with tumour necrosis factor-alpha and interleukin-1alpha. The amounts of phosphorylated signal transducer and activator of transcription-3 did not significantly increase when the cells were exposed to any of the cytokines. PMID:10075149

  1. Biologic activity of antigen receptors artificially incorporated onto B lymphocytes.

    PubMed

    Peacock, J S; Londo, T R; Roess, D A; Barisas, B G

    1986-09-15

    We describe a method for incorporating monoclonal antibody molecules onto viable murine lymphocytes and summarize the biologic activity of these artificial receptors on B cells. Mouse spleen cells incubated overnight with palmitate conjugates of a monoclonal anti-DNP IgA (protein 315) in the presence of deoxycholic acid incorporate about 50,000 antibody molecules per cell. When concentrations of deoxycholate and palmitoyl-protein 315 are carefully controlled, this labeling procedure does not affect the viability or the normal functions of the receptor-decorated cells. The incorporated antibody specifically binds DNP-antigens, although it appears to be unable to communicate directly with internal cellular components. Yet when these receptor-decorated, unprimed cells are challenged with any one of several DNP-antigens, up to 42,000 per 10(6) B cells differentiate into Ig-secreting cells. This response is about 23-fold greater than that induced in normal cell cultures and is of the same magnitude as that induced by the polyclonal B cell activator LPS. This, in addition to the observation that only about 3.6% of receptor-decorated B cells responding to DNP-conjugated polymerized flagellin (DNP-POL) produce hapten-specific antibody, demonstrates that these antigens cause polyclonal B cell differentiation. Normal spleen cells in the presence of DNP-POL and irradiated spleen cells bearing the artificial receptors do not exhibit the polyclonal antibody response. Also, the response of receptor-decorated B cell is blocked by high but nontoxic concentrations of the nonimmunogenic hapten DNP-lysine. These observations demonstrate that the polyclonal B cell response in this system requires the binding of antigen to artificial receptors on functionally viable cells. The polyclonal B cell response to a thymus-dependent antigen DNP-conjugated bovine gamma-globulin (DNP-BGG) requires the presence of the carrier-primed T cells. On the other hand, T cell depletion by anti-Thy-1

  2. Cervical arthroplasty using ProDisc-C case report.

    PubMed

    Nica, D A; Copaciu, R

    2013-03-15

    Cervical disc replacement is an emerging motion-preserving technology in the surgical treatment of the cervical degenerative disc disorders used as an alternative to the classic interbody fusion. We present a case report of a patient diagnosed with C6-7 right disc herniation who underwent anterior discectomy and received a total disc replacement using ProDisc C artificial disc prosthesis. PMID:23599830

  3. Detection of interplanetary activity using artificial neural networks

    NASA Astrophysics Data System (ADS)

    Gothoskar, Pradeep; Khobragade, Shyam

    1995-12-01

    Early detection of interplanetary activity is important when attempting to associate, with better accuracy, interplanetary phenomena with solar activity and geomagnetic disturbances. However, for a large number of interplanetary observations to be done every day, extensive data analysis is required, leading to a delay in the detection of transient interplanetary activity. In particular, the interplanetary scintillation (IPS) observations done with Ooty Radio Telescope (ORT) need extensive human effort to reduce the data and to model, often subjectively, the scintillation power spectra. We have implemented an artificial neural network (ANN) to detect interplanetary activity using the power spectrum scintillation. The ANN was trained to detect the disturbed power spectra, used as an indicator of the interplanetary activity, and to recognize normal and strong scattering spectra from a large data base of IPS spectra. The coincidence efficiency of classification by the network compared with the experts' judgement to detect the normal, disturbed and strong scattering spectra was found to be greater than 80 per cent. The neural network, when applied during the IPS mapping programme to provide early indication of interplanetary activity, would significantly help the ongoing efforts to predict geomagnetic disturbances.

  4. Antiurolithiatic Activity of Extract and Oleanolic Acid Isolated from the Roots of Lantana camara on Zinc Disc Implantation Induced Urolithiasis

    PubMed Central

    Argal, Ameeta

    2013-01-01

    The present study was done to evaluate the antiurolithiatic activity of ethanolic extract of roots (ELC 200 mg/kg) and oleanolic acid (OA 60 mg/kg, O.A. 80 mg/kg, O.A. 100 mg/kg) isolated from roots of Lantana camara in albino wistar male rats using zinc disc implantation induced urolithiatic model. The group in which only zinc disc was implanted without any treatment showed increase in calcium output (23  ± 2.7 mg/dL). Cystone receiving animals showed significant protection from such change (P < 0.01). Treatment with OA and ELC significantly reduced the calcium output at a dose of OA 60 mg/kg (P < 0.01), OA 80 mg/kg (P < 0.01), ELC 200 mg/kg (P < 0.01), and OA 100 mg/kg (P < 0.001), as compared with zinc disc implanted group. The average weight of zinc discs along with the deposited crystals in the only disc implanted group was found to be 111 ± 8.6 mg. Group that received Cystone 500 mg/kg showed significant reduction in the depositions (P < 0.001). Similarly, the rats which received OA and ELC showed reduced formation of depositions around the zinc disc (P < 0.001). The X-ray images of rats also showed significant effect of OA and ELC on urolitiasis. Thus, OA and ELC showed promising antiurolithiatic activity in dose dependant manner. PMID:23762599

  5. Accretion disc dynamo activity in local simulations spanning weak-to-strong net vertical magnetic flux regimes

    NASA Astrophysics Data System (ADS)

    Salvesen, Greg; Simon, Jacob B.; Armitage, Philip J.; Begelman, Mitchell C.

    2016-03-01

    Strongly magnetized accretion discs around black holes have attractive features that may explain enigmatic aspects of X-ray binary behaviour. The structure and evolution of these discs are governed by a dynamo-like mechanism, which channels part of the accretion power liberated by the magnetorotational instability (MRI) into an ordered toroidal magnetic field. To study dynamo activity, we performed three-dimensional, stratified, isothermal, ideal magnetohydrodynamic shearing box simulations. The strength of the self-sustained toroidal magnetic field depends on the net vertical magnetic flux, which we vary across almost the entire range over which the MRI is linearly unstable. We quantify disc structure and dynamo properties as a function of the initial ratio of mid-plane gas pressure to vertical magnetic field pressure, β _0^mid = p_gas / p_B. For 10^5 ≥ β _0^mid ≥ 10 the effective α-viscosity parameter scales as a power law. Dynamo activity persists up to and including β _0^mid = 10^2, at which point the entire vertical column of the disc is magnetic pressure dominated. Still stronger fields result in a highly inhomogeneous disc structure, with large density fluctuations. We show that the turbulent steady state βmid in our simulations is well matched by the analytic model of Begelman et al. describing the creation and buoyant escape of toroidal field, while the vertical structure of the disc can be broadly reproduced using this model. Finally, we discuss the implications of our results for observed properties of X-ray binaries.

  6. Photochemical chlorine and bromine activation from artificial saline snow

    NASA Astrophysics Data System (ADS)

    Wren, S. N.; Donaldson, D. J.; Abbatt, J. P. D.

    2013-05-01

    The activation of reactive halogen species - particularly Cl2 - from sea ice and snow surfaces is not well understood. In this study, we used a photochemical snow reactor coupled to a chemical ionization mass spectrometer to investigate the production of Br2, BrCl and Cl2 from NaCl/NaBr-doped artificial snow samples. At temperatures above the NaCl-water eutectic, illumination of samples (λ > 310 nm) in the presence of gas phase O3 led to the accelerated release of Br2, BrCl and the release of Cl2 in a process that was significantly enhanced by acidity, high surface area and additional gas phase Br2. Cl2 production was only observed when both light and ozone were present. The total halogen release depended on [O3] and pre-freezing [NaCl]. Our observations support a "halogen explosion" mechanism occurring within the snowpack which is initiated by heterogeneous oxidation, and propagated by Br2 or BrCl photolysis and by recycling of HOBr and HOCl into the snowpack. Our study implicates an important role for active chemistry occurring within the interstitial air of aged (i.e., acidic) snow for halogen activation at polar sunrise.

  7. Photochemical chlorine and bromine activation from artificial saline snow

    NASA Astrophysics Data System (ADS)

    Wren, S. N.; Donaldson, D. J.; Abbatt, J. P. D.

    2013-10-01

    The activation of reactive halogen species - particularly Cl2 - from sea ice and snow surfaces is not well understood. In this study, we used a photochemical snow reactor coupled to a chemical ionization mass spectrometer to investigate the production of Br2, BrCl and Cl2 from NaCl/NaBr-doped artificial snow samples. At temperatures above the NaCl-water eutectic, illumination of samples (λ > 310 nm) in the presence of gas phase O3 led to the accelerated release of Br2, BrCl and the release of Cl2 in a process that was significantly enhanced by acidity, high surface area and additional gas phase Br2. Cl2 production was only observed when both light and ozone were present. The total halogen release depended on [ozone] and pre-freezing [NaCl]. Our observations support a "halogen explosion" mechanism occurring within the snowpack, which is initiated by heterogeneous oxidation and propagated by Br2 or BrCl photolysis and by recycling of HOBr and HOCl into the snowpack. Our study implicates this important role of active chemistry occurring within the interstitial air of aged (i.e. acidic) snow for halogen activation at polar sunrise.

  8. Developing an active artificial hair cell using nonlinear feedback control

    NASA Astrophysics Data System (ADS)

    Joyce, Bryan S.; Tarazaga, Pablo A.

    2015-09-01

    The hair cells in the mammalian cochlea convert sound-induced vibrations into electrical signals. These cells have inspired a variety of artificial hair cells (AHCs) to serve as biologically inspired sound, fluid flow, and acceleration sensors and could one day replace damaged hair cells in humans. Most of these AHCs rely on passive transduction of stimulus while it is known that the biological cochlea employs active processes to amplify sound-induced vibrations and improve sound detection. In this work, an active AHC mimics the active, nonlinear behavior of the cochlea. The AHC consists of a piezoelectric bimorph beam subjected to a base excitation. A feedback control law is used to reduce the linear damping of the beam and introduce a cubic damping term which gives the AHC the desired nonlinear behavior. Model and experimental results show the AHC amplifies the response due to small base accelerations, has a higher frequency sensitivity than the passive system, and exhibits a compressive nonlinearity like that of the mammalian cochlea. This bio-inspired accelerometer could lead to new sensors with lower thresholds of detection, improved frequency sensitivities, and wider dynamic ranges.

  9. Multi-center, Prospective, Randomized, Controlled Investigational Device Exemption Clinical Trial Comparing Mobi-C Cervical Artificial Disc to Anterior Discectomy and Fusion in the Treatment of Symptomatic Degenerative Disc Disease in the Cervical Spine

    PubMed Central

    Bae, Hyun W.; Davis, Reginald; Gaede, Steven; Hoffman, Greg; Kim, Kee; Nunley, Pierce D.; Peterson, Daniel; Rashbaum, Ralph; Stokes, John

    2014-01-01

    Background Anterior cervical discectomy and fusion (ACDF) is the gold standard for treating symptomatic cervical disc degeneration. Cervical total disc replacements (TDRs) have emerged as an alternative for some patients. The purpose of this study was to evaluate the safety and effectiveness of a new TDR device compared with ACDF for treating single-level cervical disc degeneration. Methods This was a prospective, randomized, controlled, multicenter Food and Drug Administration (FDA) regulated Investigational Device Exemption (IDE) study. A total of 245 patients were treated (164 TDR: 81 ACDF). The primary outcome measure was overall success based on improvement in Neck Disability Index (NDI), no subsequent surgical interventions, and no adverse events (AEs) classified as major complications. Secondary outcome measures included SF-12, visual analog scale (VAS) assessing neck and arm pain, patient satisfaction, radiographic range of motion, and adjacent level degeneration. Patients were evaluated preoperatively and postoperatively at 6 weeks, 3, 6, 12, 18, and 24 months. The hypothesis was that the TDR success rate was non-inferior to ACDF at 24 months. Results Overall success rates were 73.6% for TDR and 65.3% for ACDF, confirming non-inferiority (p < 0.0025). TDR demonstrated earlier improvements with significant differences in NDI scores at 6 weeks and 3 months, and VAS neck pain and SF-12 PCS scores at 6 weeks (p<0.05). Operative level range of motion in the TDR group was maintained throughout follow-up. Radiographic evidence of inferior adjacent segment degeneration was significantly greater with ACDF at 12 and 24 months (p < 0.05). AE rates were similar. Conclusions Mobi-C TDR is a safe and effective treatment for single-level disc degeneration, producing outcomes similar to ACDF with less adjacent segment degeneration. Level of Evidence: Level I. Clinical relevance: This study adds to the literature supporting cervical TDR as a viable option to ACDF in

  10. Extracellular enzyme activities and nutrient availability during artificial groundwater recharge.

    PubMed

    Kolehmainen, Reija E; Korpela, Jaana P; Münster, Uwe; Puhakka, Jaakko A; Tuovinen, Olli H

    2009-02-01

    Natural organic matter (NOM) removal is the main objective of artificial groundwater recharge (AGR) for drinking water production and biodegradation plays a substantial role in this process. This study focused on the biodegradation of NOM and nutrient availability for microorganisms in AGR by the determination of extracellular enzyme activities (EEAs) and nutrient concentrations along a flow path in an AGR aquifer (Tuusula Water Works, Finland). Natural groundwater in the same area but outside the influence of recharge was used as a reference. Determination of the specific alpha-d-glucosidase (alpha-Glu), beta-d-glucosidase (beta-Glu), phosphomonoesterase (PME), leucine aminopeptidase (LAP) and acetate esterase (AEST) activities by fluorogenic model substrates revealed major increases in the enzymatic hydrolysis rates in the aquifer within a 10m distance from the basin. The changes in the EEAs along the flow path occurred simultaneously with decreases in nutrient concentrations. The results support the assumption that the synthesis of extracellular enzymes in aquatic environments is up and down regulated by nutrient availability. The EEAs in the basin sediment and pore water samples (down to 10cm) were in the same order of magnitude as in the basin water, suggesting similar nutritional conditions. Phosphorus was likely to be the limiting nutrient at this particular AGR site. Furthermore, the extracellular enzymes functioned in a synergistic and cooperative way. PMID:19028394

  11. Anti-urolithiatic activity of standardized extract of Biophytum sensitivum against zinc disc implantation induced urolithiasis in rats

    PubMed Central

    Pawar, Anil Tukaram; Vyawahare, Niraj S.

    2015-01-01

    Biophytum sensitivum (L.) DC (family: Oxalidaceae) has been used in the Indian indigenous system of medicine, Ayurveda, for the treatment of various health aliments including renal calculi. The present study was undertaken to investigate the anti-urolithiatic activity of standardized methanolic extract of whole plant of B. sensitivum (MBS) in rats. Urolithiasis was induced by surgical implantations of zinc disc in the urinary bladders of rats. Upon postsurgical recovery, different doses of MBS (viz., 100, 200, and 400 mg/kg body weight) were administered to zinc disc-implanted rats for the period of 7 days by the oral route. Anti-urolithiatic activity was evaluated by measuring various dimensions of stones and estimating levels of various biomarkers in serum and urine samples. A significant decrease in urinary output was observed in the disc-implanted animals, which was prevented by the MBS treatment. Supplementation with MBS caused significant improvement in glomerular filtration rate and protein excretion. The elevated levels of serum creatinine, uric acid, and blood urea nitrogen were also prevented by the MBS treatment. The MBS treatment showed reduced formation of deposition around the implanted zinc disc. The higher dose of MBS (400 mg/kg) found more effective. These results indicate that the administration of MBS significantly prevents the growth of urinary stones. The possible mechanism underlying this effect is mediated collectively through diuretic, antioxidant and anti-inflammatory effects of the plant. The results concluded that the methanolic extract of whole plant of B. sensitivum possessed significant anti-urolithiatic activity. PMID:26605159

  12. A new code to study structures in collisionally active, perturbed debris discs: application to binaries

    NASA Astrophysics Data System (ADS)

    Thébault, P.

    2012-01-01

    Context. Debris discs are traditionally studied using two distinct types of numerical models: statistical particle-in-a-box codes to study their collisional and size distribution evolution, and dynamical N-body models to study their spatial structure. The absence of collisions in N-body codes is in particular a major shortcoming, as collisional processes are expected to significantly alter the results obtained from pure N-body runs. Aims: We present a new numerical model, to study the spatial structure of perturbed debris discs in both a dynamical and collisional steady-state. We focus on the competing effects of gravitational perturbations by a massive body (planet or star), the collisional production of small grains, and the radiation pressure placing these grains in possibly dynamically unstable regions. Methods: We consider a disc of parent bodies in a dynamical steady-state, from which small radiation-pressure-affected grains are released in a series of runs, each corresponding to a different orbital position of the perturber, where particles are assigned a collisional destruction probability. These collisional runs produce successive position maps that are then recombined, following a complex procedure, to generate surface density profiles for each orbital position of the perturbing body. Results: We apply our code to the case of a circumprimary disc in a binary. We find pronounced structures inside and outside the dynamical stability regions. For low eB, the disc's structure is time varying, with spiral arms in the dynamically "forbidden" region precessing with the companion star. For high eB, the disc is strongly asymmetric but time invariant, with a pronounced density drop in the binary's periastron direction.

  13. Lab-on-a-disc for simultaneous determination of total phenolic content and antioxidant activity of beverage samples.

    PubMed

    Phonchai, Apichai; Kim, Yubin; Chantiwas, Rattikan; Cho, Yoon-Kyoung

    2016-08-16

    In this paper, we present a fully integrated and automated lab-on-a-disc for the rapid determination of the total phenolic content (TPC) and antioxidant activity (AA) of beverage samples. The simultaneous determinations of TPC and AA on a spinning disc were achieved by integrating three independent analytical techniques: the Folin-Ciocalteu method that is used to measure TPC, the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) method and the ferric reducing antioxidant power method that are used to measure AA. The TPC and AA of 8 different beverage samples, including various fruit juices, tea, wine and beer, were analyzed. Unlike conventional labor-intensive processes for measuring TPC and AA, our fully automated platform offers one-step operation and rapid analysis. PMID:27416810

  14. Artificial Limbs

    MedlinePlus

    ... you are missing an arm or leg, an artificial limb can sometimes replace it. The device, which ... activities such as walking, eating, or dressing. Some artificial limbs let you function nearly as well as ...

  15. Cost comparison of patients with 3-level artificial total lumbar disc replacements versus 360° fusion at 3 contiguous lumbar vertebral levels: an analysis of compassionate use at 1 site of the US investigational device exemption clinical trial

    PubMed Central

    Buttacavoli, Frank A.; Delamarter, Rick B.; Kanim, Linda E.A.

    2010-01-01

    Background We sought to evaluate the difference between hospital service costs of 2 treatment options for patients diagnosed with 3-level degenerative disc disease (DDD) in the lumbar spine. In this retrospective analysis, itemized billing records of hospital stay for patients with 3-level DDD treated with artificial disc replacement (ADR) were compared with those treated with circumferential fusion (standard of care). Methods Sequential 3-level DDD patients treated with either ADR (ProDisc-L; Synthes, West Chester, Pennsylvania) or circumferential fusion during the period from January 2004 to October 2005 were included. Surgeries were performed at the same hospital for all patients. The ADR-treated patients were participating in the investigational device exemption clinical trial as part of the compassionate-use arm. Patients treated with fusion at the same institution during this same time interval were evaluated. Itemized billing records were collected at least 1 year after the index surgery. Costs according to hospital service categories were compared between ADR-treated and fusion-treated patients by use of analysis of variance and multivariate statistical techniques. Results There were 43 consecutive patients treated for 3-level DDD between January 2004 and October 2005. Of these, 21 underwent 3-level ADR and 22 had a 3-level fusion procedure. There was a mean of 3 fewer hospital days for patients treated with ADR (4.77 ± 1.11 days) than for those treated with fusion (8.00 ± 1.82 days) (P < .0001). The cost of hospital services for ADR-treated patients was 49% less excluding instrumentation costs and 54% less when accounting for instrumentation. The pattern of cost was similar when workers’ compensation patients were analyzed separately. Conclusions ADR-treated 3-level patients benefited from significantly lower costs from their in-hospital stay compared with those treated by fusion. Hospital service costs were 49% (54% when instrumentation was included

  16. Herniated lumbar disc

    PubMed Central

    2011-01-01

    Introduction Herniated lumbar disc is a displacement of disc material (nucleus pulposus or annulus fibrosis) beyond the intervertebral disc space. The highest prevalence is among people aged 30 to 50 years, with a male to female ratio of 2:1. There is little evidence to suggest that drug treatments are effective in treating herniated disc. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of drug treatments, non-drug treatments, and surgery for herniated lumbar disc? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2010 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 37 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review, we present information relating to the effectiveness and safety of the following interventions: acupuncture, advice to stay active, analgesics, antidepressants, bed rest, corticosteroids (epidural injections), cytokine inhibitors (infliximab), discectomy (automated percutaneous, laser, microdiscectomy, standard), exercise therapy, heat, ice, massage, muscle relaxants, non-steroidal anti-inflammatory drugs (NSAIDs), percutaneous disc decompression, spinal manipulation, and traction. PMID:21711958

  17. Heme oxygenase-1 attenuates IL-1β induced alteration of anabolic and catabolic activities in intervertebral disc degeneration

    PubMed Central

    Hu, Bo; Shi, Changgui; Xu, Chen; Cao, Peng; Tian, Ye; Zhang, Ying; Deng, Lianfu; Chen, Huajiang; Yuan, Wen

    2016-01-01

    Intervertebral disc degeneration (IDD) is characterized by disordered extracellular matrix (ECM) metabolism, implicating subdued anabolism and enhanced catabolic activities in the nucleus pulposus (NP) of discs. Pro-inflammatory cytokines such as interleukin-1β (IL-1β) are considered to be potent mediators of ECM breakdown. Hemeoxygenase-1 (HO-1) has been reported to participate in cellular anti-inflammatory processes. The purpose of this study was to investigate HO-1 modulation of ECM metabolism in human NP cells under IL-1β stimulation. Our results revealed that expression of HO-1 decreased considerably during IDD progression. Induction of HO-1 by cobalt protoporphyrin IX attenuated the inhibition of sulfate glycosaminoglycan and collagen type II (COL-II) synthesis and ameliorated the reduced expressions of aggrecan, COL-II, SOX-6 and SOX-9 mediated by IL-1β. Induction of HO-1 also reversed the effect of IL-1β on expression of the catabolic markers matrix metalloproteinases-1, 3, 9 and 13. This was combined with inhibition of the activation of mitogen-activated protein kinase signaling. These findings suggest that HO-1 might play a pivotal role in IDD, and that manipulating HO-1 expression might mitigate the impairment of ECM metabolism in NP, thus potentially offering a novel therapeutic approach to the treatment of IDD. PMID:26877238

  18. ISSLS PRIZE WINNER: INHIBITION OF NF-κB ACTIVITY AMELIORATES AGE-ASSOCIATED DISC DEGENERATION IN A MOUSE MODEL OF ACCELERATED AGING

    PubMed Central

    Nasto, Luigi A.; Seo, Hyoung-Yeon; Robinson, Andria R.; Tilstra, Jeremy S.; Clauson, Cheryl L.; Sowa, Gwendolyn A.; Ngo, Kevin; Dong, Qing; Pola, Enrico; Lee, Joon Y.; Niedernhofer, Laura J.; Kang, James D.; Robbins, Paul D.; Vo, Nam V.

    2012-01-01

    Study Design NF-κB activity was pharmacologically and genetically blocked in an accelerated aging mouse model to mitigate age-related disc degenerative changes. Objective To study the mediatory role of NF-κB signaling pathway in age-dependent intervertebral disc degeneration. Summary of Background Data Aging is a major contributor to intervertebral disc degeneration (IDD), but the molecular mechanism behind this process is poorly understood. NF-κB is a family of transcription factors which play a central role in mediating cellular response to damage, stress, and inflammation. Growing evidence implicates chronic NF-κB activation as a culprit in many aging-related diseases, but its role in aging-related IDD has not been adequately explored. We studied the effects of NF-κB inhibition on IDD using a DNA repair-deficient mouse model of accelerated aging (Ercc1-/Δ mice) previously been reported to exhibit age-related IDD. Methods Systemic inhibition of NF-κB activation was achieved either genetically by deletion of one allele of the NF-κB subunit p65 (Ercc1-/Δp65+/- mice) or pharmacologically by chronic intra-peritoneal administration of the Nemo Binding Domain (8K-NBD) peptide to block the formation of the upstream activator of NF-κB, IκB Inducible Kinase (IKK), in Ercc1-/Δ mice. Disc cellularity, total proteoglycan content and proteoglycan synthesis of treated mice and untreated controls were assessed. Results Decreased disc matrix proteoglycan content, a hallmark feature of IDD, and elevated disc NF-κB activity were observed in discs of progeroid Ercc1-/Δ mice and naturally aged wild-type compared to young WT mice. Systemic inhibition of NF-κB by the 8K-NBD peptide in Ercc1-/Δ mice increased disc proteoglycan synthesis and ameriolated loss disc cellularity and matrix proteoglycan. These results were confirmed genetically by using the p65 haploinsufficient Ercc1-/Δp65+/- mice. Conclusion These findings demonstrate that the IKK/NF-κB signaling pathway

  19. Early active rehabilitation after surgery for lumbar disc herniation: a prospective, randomized study of psychometric assessment in 50 patients.

    PubMed

    Kjellby-Wendt, G; Styf, J; Carlsson, S G

    2001-10-01

    In a randomized study, using psychometric assessment, we evaluated two training programs before and after surgical treatment of lumbar disc herniation. 26 patients were treated according to an early active training program (treatment group). 24 patients followed a traditional less active training program (control group). Before surgery, the patients filled in the following questionnaires 3 and 12 months after surgery: Multidimensional Pain Inventory (MPI), State and Trait Anxiety Inventory, and Beck Depression Inventory. Pain was assessed by the patient's pain drawing and a visual analog scale. Both groups improved as regards pain severity and state of anxiety. The MPI parameter, pain interference, improved more in the early active treatment group than in the control group. This suggests that the early active training program has a positive effect on the way patients cope with pain in their daily lives. PMID:11728081

  20. Effect of a preoperative instructional digital video disc on patient knowledge and preparedness for engaging in postoperative care activities.

    PubMed

    Ong, Joe; Miller, Pamela S; Appleby, Renee; Allegretto, Rebecca; Gawlinski, Anna

    2009-03-01

    This project determined the effects of developing and implementing a preoperative instructional digital video disc (DVD) on patients' level of knowledge, preparedness, and perceived ability to participate in postoperative care activities. Content areas that were incorporated into the preoperative instructional DVD included: pain management, surgical drainage, vital signs, incentive spirometry, cough and deep breathe, chest physiotherapy, anti-embolism stockings/sequential compression device, ambulation, diet/bowel activity/urine output, and discharge. A system was created to ensure that patients consistently received the preoperative instructional DVD prior to surgery. The instructional media product was found to be effective in increasing pre-operative knowledge and preparedness of patients and their families. Nurses reported higher levels of knowledge and engagement among patients and their families related to postoperative activities. PMID:19167553

  1. Ecdysteroid promotes cell cycle progression in the Bombyx wing disc through activation of c-Myc.

    PubMed

    Moriyama, Minoru; Osanai, Kohji; Ohyoshi, Tomokazu; Wang, Hua-Bing; Iwanaga, Masashi; Kawasaki, Hideki

    2016-03-01

    Developmental switching from growth to metamorphosis in imaginal primordia is an essential process of adult body planning in holometabolous insects. Although it is disciplined by a sequential action of the ecdysteroid, molecular mechanisms linking to cell proliferation are poorly understood. In the present study, we investigated the expression control of cell cycle-related genes by the ecdysteroid using the wing disc of the final-instar larvae of the silkworm, Bombyx mori. We found that the expression level of c-myc was remarkably elevated in the post-feeding cell proliferation phase, which coincided with a small increase in ecdysteroid titer. An in vitro wing disc culture showed that supplementation of the moderate level of the ecdysteroid upregulated c-myc expression within an hour and subsequently increased the expression of cell cycle core regulators, including A-, B-, D-, and E-type cyclin genes, Cdc25 and E2F1. We demonstrated that c-myc upregulation by the ecdysteroid was not inhibited in the presence of a protein synthesis inhibitor, suggesting a possibility that the ecdysteroid directly stimulates c-myc expression. Finally, results from the administration of a c-Myc inhibitor demonstrated that c-Myc plays an essential role in 20E-inducible cell proliferation. These findings suggested a novel pathway for ecdysteroid-inducible cell proliferation in insects, and it is likely to be conserved between insects and mammals in terms of steroid hormone regulation. PMID:26696544

  2. On different types of instabilities in black hole accretion discs: implications for X-ray binaries and active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Janiuk, Agnieszka; Czerny, Bożena

    2011-07-01

    We discuss two important instability mechanisms that may lead to the limit-cycle oscillations of the luminosity of the accretion discs around compact objects: ionization instability and radiation pressure instability. Ionization instability is well established as a mechanism of X-ray novae eruptions in black hole binary systems, but its applicability to active galactic nuclei (AGN) is still problematic. Radiation pressure theory has still a very weak observational background in any of these sources. In this paper, we attempt to confront the parameter space of these instabilities with the observational data. At the basis of this simple survey of sources properties, we argue that the radiation pressure instability is likely to be present in several Galactic sources with the Eddington ratios being above 0.15 and in AGN with the Eddington ratio above 0.025. Our results favour the parametrization of the viscosity through the geometrical mean of the radiation and gas pressure in both Galactic sources and AGN. More examples of the quasi-regular outbursts in the time-scales of 100 s in Galactic sources and hundreds of years in AGN are needed to formulate firm conclusions. We also show that the disc sizes in the X-ray novae are consistent with the ionization instability. This instability may also considerably influence the lifetime cycle and overall complexity in the supermassive black hole environment.

  3. Effectiveness of behavioral graded activity after first-time lumbar disc surgery: short term results of a randomized controlled trial.

    PubMed

    Ostelo, R W J G; de Vet, H C W; Berfelo, M W; Kerckhoffs, M R; Vlaeyen, J W S; Wolters, P M J C; van den Brandt, P A

    2003-12-01

    Behavioral approaches to treating patients following lumbar disc surgery are becoming increasingly popular. The treatment method is based on the assumption that pain and pain disability are not only influenced by somatic pathology, if found, but also by psychological and social factors. A recent study highlighted the effectiveness of cognitive-behavioral interventions, as compared to no treatment, for chronic low back patients. However, to the authors' knowledge, there is no randomized controlled trial that evaluates a behavioral program for patients following lumbar disc surgery. The purpose of this study was to assess the effectiveness of a behavioral graded activity (BGA) program compared to usual care (UC) in physiotherapy following first-time lumbar disc surgery. The BGA program was a patient-tailored intervention based upon operant therapy. The essence of the BGA is to teach patients that it is safe to increase activity levels. The study was designed as a randomized controlled trial. Assessments were carried out before and after treatment by an observer blinded to treatment allocation. Patients suffering residual symptoms restricting their activities of daily living and/or work at the 6 weeks post-surgery consultation by the neurosurgeon were included. The exclusion criteria were: complications during surgery, any relevant underlying pathology, and any contraindication to physiotherapy or the BGA program. Primary outcome measures were the patient's Global Perceived Effect and the functional status. Secondary measures were: fear of movement, viewing pain as extremely threatening, pain, severity of the main complaint, range of motion, and relapses. Physiotherapists in the BGA group received proper training. Between November 1997 and December 1999, 105 patients were randomized; 53 into the UC group and 52 into the BGA group. The unadjusted analysis shows a 19.3% (95% CI: 0.1 to 38.5) statistically significant difference to the advantage of the UC group on Global

  4. Sorption and biodegradation of artificial sweeteners in activated sludge processes.

    PubMed

    Tran, Ngoc Han; Gan, Jie; Nguyen, Viet Tung; Chen, Huiting; You, Luhua; Duarah, Ankur; Zhang, Lifeng; Gin, Karina Yew-Hoong

    2015-12-01

    There is limited information on the occurrence and removal of artificial sweeteners (ASs) in biological wastewater treatment plants, and in particular, the contribution of sorption and biodegradation to their removal. This study investigated the fate of ASs in both the aqueous and solid phases in a water reclamation plant (WRP). All the four targeted ASs, i.e. acesulfame (ACE), sucralose (SUC), cyclamate (CYC) and saccharine (SAC), were detected in both the aqueous and solid phases of raw influent and primary effluent samples. The concentrations of CYC and SAC in secondary effluent or MBR permeate were below their method detection limits. ACE and SUC were persistent throughout the WRP, whereas CYC and SAC were completely removed in biological treatment (>99%). Experimental results showed that sorption played a minor role in the elimination of the ASs due to the relatively low sorption coefficients (Kd), where Kd<500L/kg. In particular, the poor removal of ACE and SUC in the WRP may be attributed to their physiochemical properties (i.e. logKow<0 or logD<3.2) and chemical structures containing strong withdrawing electron functional groups in heterocyclic rings (i.e. chloride and sulfonate). PMID:26342347

  5. Artificial cytoskeletal structures within enzymatically active bio-inorganic protocells.

    PubMed

    Kumar, Ravinash Krishna; Li, Mei; Olof, Sam N; Patil, Avinash J; Mann, Stephen

    2013-02-11

    The fabrication of enzymatically active, semi-permeable bio-inorganic protocells capable of self-assembling a cytoskeletal-like interior and undergoing small-molecule dephosphorylation reactions is described. Reversible disassembly of an amino acid-derived supramolecular hydrogel within the internalized reaction space is used to tune the enzymatic activity of the nanoparticle-bounded inorganic compartments. PMID:23027575

  6. Prosthetic lumbar disc replacement for degenerative disc disease.

    PubMed

    Kulkarni, Arvind G; Diwan, Ashish D

    2005-12-01

    Mechanical articulated device to replace intervertebral disc as a treatment for low back pain secondary to disc degeneration has emerged as a promising tool for selected patients. The potential advantages are prevention of adjacent segment degeneration, maintenance of mobility as well as avoidance of all the complications associated with fusion. The short-term results have been comparable to that of fusion, a few mid-term results have shown mixed outcome, but information on long-term results and performance are not available at present. The rationale for lumbar disc arthroplasty, indications, contraindications, the various artificial devices in the market and the concepts intrinsic to each of them, basic technique of insertion, complications are discussed and a brief summary of our experience with one of the devices is presented. PMID:16565543

  7. Galaxy Zoo: the effect of bar-driven fuelling on the presence of an active galactic nucleus in disc galaxies

    NASA Astrophysics Data System (ADS)

    Galloway, Melanie A.; Willett, Kyle W.; Fortson, Lucy F.; Cardamone, Carolin N.; Schawinski, Kevin; Cheung, Edmond; Lintott, Chris J.; Masters, Karen L.; Melvin, Thomas; Simmons, Brooke D.

    2015-04-01

    We study the influence of the presence of a strong bar in disc galaxies which host an active galactic nucleus (AGN). Using data from the Sloan Digital Sky Survey and morphological classifications from the Galaxy Zoo 2 project, we create a volume-limited sample of 19 756 disc galaxies at 0.01 < z < 0.05 which have been visually examined for the presence of a bar. Within this sample, AGN host galaxies have a higher overall percentage of bars (51.8 per cent) than inactive galaxies exhibiting central star formation (37.1 per cent). This difference is primarily due to known effects: that the presence of both AGN and galactic bars is strongly correlated with both the stellar mass and integrated colour of the host galaxy. We control for this effect by examining the difference in AGN fraction between barred and unbarred galaxies in fixed bins of mass and colour. Once this effect is accounted for, there remains a small but statistically significant increase that represents 16 per cent of the average barred AGN fraction. Using the L_{[O III]}/MBH ratio as a measure of AGN strength, we show that barred AGNs do not exhibit stronger accretion than unbarred AGNs at a fixed mass and colour. The data are consistent with a model in which bar-driven fuelling does contribute to the probability of an actively growing black hole, but in which other dynamical mechanisms must contribute to the direct AGN fuelling via smaller, non-axisymmetric perturbations.

  8. Active galactic nuclei at z ˜ 1.5 - III. Accretion discs and black hole spin

    NASA Astrophysics Data System (ADS)

    Capellupo, D. M.; Netzer, H.; Lira, P.; Trakhtenbrot, B.; Mejía-Restrepo, J.

    2016-07-01

    This is the third paper in a series describing the spectroscopic properties of a sample of 39 AGN at z ˜ 1.5, selected to cover a large range in black hole mass (MBH) and Eddington ratio (L/LEdd). In this paper, we continue the analysis of the VLT/X-shooter observations of our sample with the addition of nine new sources. We use an improved Bayesian procedure, which takes into account intrinsic reddening, and improved MBH estimates, to fit thin accretion disc (AD) models to the observed spectra and constrain the spin parameter (a*) of the central black holes. We can fit 37 out of 39 AGN with the thin AD model, and for those with satisfactory fits, we obtain constraints on the spin parameter of the BHs, with the constraints becoming generally less well defined with decreasing BH mass. Our spin parameter estimates range from ˜-0.6 to maximum spin for our sample, and our results are consistent with the `spin-up' scenario of BH spin evolution. We also discuss how the results of our analysis vary with the inclusion of non-simultaneous GALEX photometry in our thin AD fitting. Simultaneous spectra covering the rest-frame optical through far-UV are necessary to definitively test the thin AD theory and obtain the best constraints on the spin parameter.

  9. Active galactic nuclei at z ˜ 1.5: III. Accretion discs and Black Hole Spin

    NASA Astrophysics Data System (ADS)

    Capellupo, D. M.; Netzer, H.; Lira, P.; Trakhtenbrot, B.; Mejía-Restrepo, J.

    2016-04-01

    This is the third paper in a series describing the spectroscopic properties of a sample of 39 AGN at z ˜ 1.5, selected to cover a large range in black hole mass (MBH) and Eddington ratio (L/LEdd). In this paper, we continue the analysis of the VLT/X-shooter observations of our sample with the addition of 9 new sources. We use an improved Bayesian procedure, which takes into account intrinsic reddening, and improved MBH estimates, to fit thin accretion disc (AD) models to the observed spectra and constrain the spin parameter (a★) of the central black holes. We can fit 37 out of 39 AGN with the thin AD model, and for those with satisfactory fits, we obtain constraints on the spin parameter of the BHs, with the constraints becoming generally less well defined with decreasing BH mass. Our spin parameter estimates range from ˜-0.6 to maximum spin for our sample, and our results are consistent with the "spin-up" scenario of BH spin evolution. We also discuss how the results of our analysis vary with the inclusion of non-simultaneous GALEX photometry in our thin AD fitting. Simultaneous spectra covering the rest-frame optical through far-UV are necessary to definitively test the thin AD theory and obtain the best constraints on the spin parameter.

  10. Synthesis and characterization of a Redox-active artificial ion channel.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The synthesis and characterization of an artificial ion channel containing both fluorescent and redox-active centers is described. fluorescence spectroscopy was used to study qualitative and quantitative aspects of the coordination of alkali metal cations and black lipid membrane studies were used ...

  11. Artificial masculinization in tilapia involves androgen receptor activation.

    PubMed

    Golan, Matan; Levavi-Sivan, Berta

    2014-10-01

    Estrogens have a pivotal role in natural female sexual differentiation of tilapia while lack of steroids results in testicular development. Despite the fact that androgens do not participate in natural sex differentiation, synthetic androgens, mainly 17-α-methyltestosterone (MT) are effective in the production of all-male fish in aquaculture. The sex inversion potency of synthetic androgens may arise from their androgenic activity or else as inhibitors of aromatase activity. The current study is an attempt to differentiate between the two alleged activities in order to evaluate their contribution to the sex inversion process and aid the search for novel sex inversion agents. In the present study, MT inhibited aromatase activity, when applied in vitro as did the non-aromatizable androgen dihydrotestosterone (DHT). In comparison, exposure to fadrozole, a specific aromatase inhibitor, was considerably more effective. Androgenic activity of MT was evaluated by exposure of Sciaenochromis fryeri fry to the substance and testing for the appearance of blue color. Flutamide, an androgen antagonist, administered concomitantly with MT, reduced the appearance of the blue color and the sex inversion potency of MT in a dose-dependent manner. In tilapia, administration of MT, fadrozole or DHT resulted in efficient sex inversion while flutamide reduced the sex inversion potency of all three compounds. In the case of MT and DHT the decrease in sex inversion efficiency caused by flutamide is most likely due to the direct blocking of the androgen binding to its cognate receptor. The negative effect of flutamide on the efficiency of the fadrozole treatment may indicate that the masculinizing activity of fadrozole may be attributed to excess, un-aromatized, androgens accumulated in the differentiating gonad. The present study shows that when androgen receptors are blocked, there is a reduction in the efficiency of sex inversion treatments. Our results suggest that in contrast to

  12. Janus discs.

    PubMed

    Walther, Andreas; André, Xavier; Drechsler, Markus; Abetz, Volker; Müller, Axel H E

    2007-05-16

    We describe the synthesis and the solution properties of sheet- and disclike Janus particles, containing an inner crosslinked polybutadiene (PB) layer and two different outer sides of polystyrene (PS) and poly(tert-butyl methacrylate) (PtBMA). The structures formed upon adsorption of the flat Janus particles onto solid substrates as well as in THF solution are investigated. The Janus discs are obtained in a template-assisted synthetic pathway followed by sonication. Selectively crosslinking the lamellar PB domains in a well-ordered lamellar microphase-separated bulk morphology of PS-block-PB-block-PtBMA (SBT) block terpolymers leads to the conservation of the compartmentalization of the two outer blocks. Sonication of the crosslinked block terpolymer templates renders soluble sheet- and disclike Janus particles, the size of which can be tuned from the micrometer range down to the nanometer scale. Small-angle X-ray scattering, transmission electron microscopy, dynamic light scattering, scanning force microscopy, and scanning electron microscopy are used to characterize the template-assisted synthetic process and the solution properties. Cryogenic transmission electron microscopy in THF and TEM of particles, embedded into a photo-crosslinkable silicon oil, indicate a supramolecular aggregation behavior of the Janus discs in concentrated solutions. Pendant drop tensiometry demonstrates that Janus sheets and discs can be used to stabilize liquid-liquid interfaces, rendering these materials interesting for future applications. PMID:17441717

  13. Optimal Recognition Method of Human Activities Using Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Oniga, Stefan; József, Sütő

    2015-12-01

    The aim of this research is an exhaustive analysis of the various factors that may influence the recognition rate of the human activity using wearable sensors data. We made a total of 1674 simulations on a publically released human activity database by a group of researcher from the University of California at Berkeley. In a previous research, we analyzed the influence of the number of sensors and their placement. In the present research we have examined the influence of the number of sensor nodes, the type of sensor node, preprocessing algorithms, type of classifier and its parameters. The final purpose is to find the optimal setup for best recognition rates with lowest hardware and software costs.

  14. ACTIVE MEDIA: Electronic and thermal lensing in diode end-pumped Yb:YAG laser rods and discs

    NASA Astrophysics Data System (ADS)

    Antipov, Oleg L.; Anashkina, E. A.; Fedorova, K. A.

    2009-12-01

    The lensing effects in diode end-pumped Yb:YAG laser rods and discs are studied. Two mechanisms of refractive-index changes are taken into account, thermal and electronic (due to the difference between the excited- and ground-state Yb3+ polarisabilities), as well as pump-induced deformation of the laser crystal. Under pulsed pumping, the electronic lensing effect prevails over the thermal one in both rods and discs. In rods pumped by a highly focused cw beam, the dioptric power of the electronic lens exceeds that of the thermal lens, whereas in discs steady-state lensing is predominantly due to the thermal mechanism.

  15. Reduced mitochondrial and ascorbate-glutathione activity after artificial ageing in soybean seed.

    PubMed

    Xin, Xia; Tian, Qian; Yin, Guangkun; Chen, Xiaoling; Zhang, Jinmei; Ng, Sophia; Lu, Xinxiong

    2014-01-15

    The effect of artificial ageing on the relationship between mitochondrial activities and the antioxidant system was studied in soybean seeds (Glycine max L. cv. Zhongdou No. 27). Ageing seeds for 18d and 41d at 40°C reduced germination from 99% to 52% and 0%, respectively. In comparison to the control, malondialdehyde content and leachate conductivity in aged seeds increased and were associated with membrane damage. Transmission electron microscopy and Percoll density gradient centrifugation showed that aged seeds mainly contained poorly developed mitochondria in which respiration and marker enzymes activities were significantly reduced. Heavy mitochondria isolated from the interface of the 21% and 40% Percoll were analyzed. Mitochondrial antioxidant enzymes activities including superoxide dismutase, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase, and dehydroascorbate reductase were significantly reduced in aged seeds. A decrease in total ascorbic acid (ASC) and glutathione (GSH) content as well as the reduced/oxidized ratio of ASC and GSH in mitochondria with prolonged ageing showed that artificial ageing reduced ASC-GSH cycle activity. These results suggested an elevated reactive oxygen species (ROS) level in the aged seeds, which was confirmed by measurements of superoxide radical and hydrogen peroxide levels. We conclude that mitochondrial dysfunction in artificially aged seeds is due to retarded mitochondrial and ASC-GSH cycle activity and elevated ROS accumulation. PMID:24331429

  16. Localized epigenetic silencing of a damage-activated WNT enhancer limits regeneration in mature Drosophila imaginal discs

    PubMed Central

    Harris, Robin E; Setiawan, Linda; Saul, Josh; Hariharan, Iswar K

    2016-01-01

    Many organisms lose the capacity to regenerate damaged tissues as they mature. Damaged Drosophila imaginal discs regenerate efficiently early in the third larval instar (L3) but progressively lose this ability. This correlates with reduced damage-responsive expression of multiple genes, including the WNT genes wingless (wg) and Wnt6. We demonstrate that damage-responsive expression of both genes requires a bipartite enhancer whose activity declines during L3. Within this enhancer, a damage-responsive module stays active throughout L3, while an adjacent silencing element nucleates increasing levels of epigenetic silencing restricted to this enhancer. Cas9-mediated deletion of the silencing element alleviates WNT repression, but is, in itself, insufficient to promote regeneration. However, directing Myc expression to the blastema overcomes repression of multiple genes, including wg, and restores cellular responses necessary for regeneration. Localized epigenetic silencing of damage-responsive enhancers can therefore restrict regenerative capacity in maturing organisms without compromising gene functions regulated by developmental signals. DOI: http://dx.doi.org/10.7554/eLife.11588.001 PMID:26840050

  17. Modeling and optimization of an elastic arthroplastic disc for a degenerated disc

    NASA Astrophysics Data System (ADS)

    Ghouchani, Azadeh; Ravari, Mohammad; Mahmoudi, Farid

    2011-10-01

    A three-dimensional finite element model (FEM) of the L3-L4 motion segment using ABAQUS v 6.9 has been developed. The model took into account the material nonlinearities and is imposed different loading conditions. In this study, we validated the model by comparison of its predictions with several sets of experimental data. Disc deformation under compression and segmental rotational motions under moment loads for the normal disc model agreed well with the corresponding in vivo studies. By linking ABAQUS with MATLAB 2010.a, we determined the optimal Young s modulus as well as the Poisson's ratio for the artificial disc under different physiologic loading conditions. The results of the present study confirmed that a well-designed elastic arthroplastic disc preferably has an annulus modulus of 19.1 MPa and 1.24 MPa for nucleus section and Poisson ratio of 0.41 and 0.47 respectively. Elastic artificial disc with such properties can then achieve the goal of restoring the disc height and mechanical function of intact disc under different loading conditions and so can reduce low back pain which is mostly caused due to disc degeneration.

  18. A Novel Wearable Sensor-Based Human Activity Recognition Approach Using Artificial Hydrocarbon Networks

    PubMed Central

    Ponce, Hiram; Martínez-Villaseñor, María de Lourdes; Miralles-Pechuán, Luis

    2016-01-01

    Human activity recognition has gained more interest in several research communities given that understanding user activities and behavior helps to deliver proactive and personalized services. There are many examples of health systems improved by human activity recognition. Nevertheless, the human activity recognition classification process is not an easy task. Different types of noise in wearable sensors data frequently hamper the human activity recognition classification process. In order to develop a successful activity recognition system, it is necessary to use stable and robust machine learning techniques capable of dealing with noisy data. In this paper, we presented the artificial hydrocarbon networks (AHN) technique to the human activity recognition community. Our artificial hydrocarbon networks novel approach is suitable for physical activity recognition, noise tolerance of corrupted data sensors and robust in terms of different issues on data sensors. We proved that the AHN classifier is very competitive for physical activity recognition and is very robust in comparison with other well-known machine learning methods. PMID:27399696

  19. A Novel Wearable Sensor-Based Human Activity Recognition Approach Using Artificial Hydrocarbon Networks.

    PubMed

    Ponce, Hiram; Martínez-Villaseñor, María de Lourdes; Miralles-Pechuán, Luis

    2016-01-01

    Human activity recognition has gained more interest in several research communities given that understanding user activities and behavior helps to deliver proactive and personalized services. There are many examples of health systems improved by human activity recognition. Nevertheless, the human activity recognition classification process is not an easy task. Different types of noise in wearable sensors data frequently hamper the human activity recognition classification process. In order to develop a successful activity recognition system, it is necessary to use stable and robust machine learning techniques capable of dealing with noisy data. In this paper, we presented the artificial hydrocarbon networks (AHN) technique to the human activity recognition community. Our artificial hydrocarbon networks novel approach is suitable for physical activity recognition, noise tolerance of corrupted data sensors and robust in terms of different issues on data sensors. We proved that the AHN classifier is very competitive for physical activity recognition and is very robust in comparison with other well-known machine learning methods. PMID:27399696

  20. Redundant disc

    NASA Technical Reports Server (NTRS)

    Barack, W. N.; Domas, P. A.; Beekman, S. W. (Inventor)

    1978-01-01

    A rotatable disc is described that consists of parallel plates tightly joined together for rotation about a hub. Each plate is provided with several angularly projecting spaced lands. The lands of each plate are interposed in alternating relationship between the lands of the next adjacent plate. In this manner, circumferential displacement of adjacent sectors in any one plate is prevented in the event that a crack develops. Each plate is redundantly sized so that, in event of structural failure of one plate, the remaining plates support a proportionate share of the load of the failed plate. The plates are prevented from separating laterally through the inclusion of generally radially extending splines which are inserted to interlock cooperating, circumferentially adjacent lands.

  1. Features of artificial ULF/VLF signals induced by SURA facility under increased solar activity conditions

    NASA Astrophysics Data System (ADS)

    Kotik, Dmitry; Ryabov, Alexander; Pershin, Alexsander; Ermakova, Elena

    It was conducted a comprehensive study of artificial ionospheric signal generation in the ULF/VLF bands at SURA facility during the past four years. We investigated the influence of geomagnetic activity on the characteristics of artificial low-frequency signals in recent years under the background of increasing solar activity. No correlation with variations of Earth's magnetic field was observed for weak geomagnetic disturbances (Kp < 3). It was observed decreasing in the amplitude of signals at frequencies of 3 and 6 Hz, while the VLF signals at frequencies of 2 and 2.6 kHz increased for growth phase of the geomagnetic field perturbations during a small magnetic storms October 7, 2011 (Ki = 4 according to Moscow station). A similar pattern was traced in 2013 during storms March 21 (Kp = 5), May 24-25 (Kp = 5 +) and August 16 (Kp = 5 +). There are two possible reasons for the observed dependence - increasing the absorption of HF and VLF waves in the lower ionosphere, and / or reduction of the critical frequency of the F-layer, usually accompanied by a magnetic storm. The last factor is perhaps the most likely. This dependence was traced more convincingly on May 24-25, when during a storm time SURE had operated from evening until 6:00 MST in the morning. Signal amplitude explicitly followed the F- layer critical frequency variation. Some of the measurements in June 2012 were conducted during a magnetic storm on June 16-18, (Kp = 6). It was also found a decrease in the amplitude of the signal at the rise of the magnetic disturbance. In addition, during the daytime session 18.06.2012 during the recovery phase, it was detected modulation of artificial signals at frequencies 11 and 17 Hz with a period of 30 seconds. Note that the period of 30s is the main period of oscillation of the geomagnetic field line passing through the SURA facility, and more, the periods for torsional and the toroidal oscillation modes of this field line surprising coincidence for SURA

  2. Mechanotransduction in intervertebral discs

    PubMed Central

    Tsai, Tsung-Ting; Cheng, Chao-Min; Chen, Chien-Fu; Lai, Po-Liang

    2014-01-01

    Mechanotransduction plays a critical role in intracellular functioning—it allows cells to translate external physical forces into internal biochemical activities, thereby affecting processes ranging from proliferation and apoptosis to gene expression and protein synthesis in a complex web of interactions and reactions. Accordingly, aberrant mechanotransduction can either lead to, or be a result of, a variety of diseases or degenerative states. In this review, we provide an overview of mechanotransduction in the context of intervertebral discs, with a focus on the latest methods of investigating mechanotransduction and the most recent findings regarding the means and effects of mechanotransduction in healthy and degenerative discs. We also provide some discussion of potential directions for future research and treatments. PMID:25267492

  3. [Cervical disc herniation].

    PubMed

    Schnake, K J; Hoffmann, C-H; Kandziora, F

    2012-12-01

    The cervical disc herniation is characterized by prolapsed nucleus pulposus material through the annulus into the spinal canal. The local mechanical or chemical irritation of neural structures typically leads to symptoms of radiculopathy, cervicocephalgia or myelopathy. Pronounced sensorimotor deficits or intractable pain constitute surgical treatment. In all other cases conservative treatment is indicated, including pain medication, active and passive physiotherapy, and local injections, respectively. Anterior cervical discectomy and interbody fusion (ACDF) is still the surgical treatment of choice. Predominantly, cages with or without plates are in use to obtain solid fusion. The implantation of a total disc replacement is a viable alternative, if no contraindications exist. Other surgical techniques may be performed in proper selected cases. The overall clinical and radiological results of both surgical and conservative treatment are good. PMID:23296562

  4. Intervertebral disc disease.

    PubMed

    Simpson, S T

    1992-07-01

    This article describes the functional anatomy of intervertebral discs and their relationship to the vertebrae and spinal cord. The pathologic events and clinical complications of intervertebral disc disease are described. A discussion of proper staging of disc disease and appropriate conservative management of degenerative disc disease is included. PMID:1641922

  5. Application of Artificial Intelligence to the Prediction of the Antimicrobial Activity of Essential Oils

    PubMed Central

    Daynac, Mathieu; Cortes-Cabrera, Alvaro; Prieto, Jose M.

    2015-01-01

    Essential oils (EOs) are vastly used as natural antibiotics in Complementary and Alternative Medicine (CAM). Their intrinsic chemical variability and synergisms/antagonisms between its components make difficult to ensure consistent effects through different batches. Our aim is to evaluate the use of artificial neural networks (ANNs) for the prediction of their antimicrobial activity. Methods. The chemical composition and antimicrobial activity of 49 EOs, extracts, and/or fractions was extracted from NCCLS compliant works. The fast artificial neural networks (FANN) software was used and the output data reflected the antimicrobial activity of these EOs against four common pathogens: Staphylococcus aureus, Escherichia coli, Candida albicans, and Clostridium perfringens as measured by standardised disk diffusion assays. Results. ANNs were able to predict >70% of the antimicrobial activities within a 10 mm maximum error range. Similarly, ANNs were able to predict 2 or 3 different bioactivities at the same time. The accuracy of the prediction was only limited by the inherent errors of the popular antimicrobial disk susceptibility test and the nature of the pathogens. Conclusions. ANNs can be reliable, fast, and cheap tools for the prediction of the antimicrobial activity of EOs thus improving their use in CAM. PMID:26457111

  6. Broken discs: warp propagation in accretion discs

    NASA Astrophysics Data System (ADS)

    Nixon, Christopher J.; King, Andrew R.

    2012-04-01

    We simulate the viscous evolution of an accretion disc around a spinning black hole. In general, any such disc is misaligned, and warped by the Lense-Thirring effect. Unlike previous studies, we use effective viscosities constrained to be consistent with the internal fluid dynamics of the disc. We find that non-linear fluid effects, which reduce the effective viscosities in warped regions, can promote breaking of the disc into two distinct planes. This occurs when the Shakura & Sunyaev dimensionless viscosity parameter α is ≲0.3 and the initial angle of misalignment between the disc and hole is ≳45°. The break can be a long-lived feature, propagating outwards in the disc on the usual alignment time-scale, after which the disc is fully co-aligned or counter-aligned with the hole. Such a break in the disc may be significant in systems where we know the inclination of the outer accretion disc to the line of sight, such as some X-ray binaries: the inner disc, and so any jets, may be noticeably misaligned with respect to the orbital plane.

  7. Disc-planet interactions in subkeplerian discs

    NASA Astrophysics Data System (ADS)

    Paardekooper, S.-J.

    2009-11-01

    Context: One class of protoplanetary disc models, the X-wind model, predicts strongly subkeplerian orbital gas velocities, a configuration that can be sustained by magnetic tension. Aims: We investigate disc-planet interactions in these subkeplerian discs, focusing on orbital migration for low-mass planets and gap formation for high-mass planets. Methods: We use linear calculations and nonlinear hydrodynamical simulations to measure the torque and look at gap formation. In both cases, the subkeplerian nature of the disc is treated as a fixed external constraint. Results: We show that, depending on the degree to which the disc is subkeplerian, the torque on low-mass planets varies between the usual type I torque and the one-sided outer Lindblad torque, which is also negative but an order of magnitude stronger. In strongly subkeplerian discs, corotation effects can be ignored, making migration fast and inward. Gap formation near the planet's orbit is more difficult in such discs, since there are no resonances close to the planet accommodating angular momentum transport. The location of the gap is shifted inwards with respect to the planet, leaving the planet on the outside of a surface density depression. Conclusions: Depending on the degree to which a protoplanetary disc is subkeplerian, disc-planet interactions can be very different from the usual Keplerian picture, making these discs in general more hazardous for young planets.

  8. In vitro biomechanics of cervical disc arthroplasty with the ProDisc-C total disc implant.

    PubMed

    DiAngelo, Denis J; Foley, Kevin T; Morrow, Brian R; Schwab, John S; Song, Jung; German, John W; Blair, Eve

    2004-09-15

    An in vitro biomechanical study was conducted to compare the effects of disc arthroplasty and anterior cervical fusion on cervical spine biomechanics in a multilevel human cadaveric model. Three spine conditions were studied: harvested, single-level cervical disc arthroplasty, and single-level fusion. A programmable testing apparatus was used that replicated physiological flexion/extension, lateral bending, and axial rotation. Measurements included vertebral motion, applied load, and bending moments. Relative rotations at the superior, treated, and inferior motion segment units (MSUs) were normalized with respect to the overall rotation of those three MSUs and compared using a one-way analysis of variance with Student-Newman-Keuls test (p < 0.05). Simulated fusion decreased motion across the treated site relative to the harvested and disc arthroplasty conditions. The reduced motion at the treated site was compensated at the adjacent segments by an increase in motion. For all modes of testing, use of an artificial disc prosthesis did not alter the motion patterns at either the instrumented level or adjacent segments compared with the harvested condition, except in extension. PMID:15636563

  9. Artificial Cervical Disc Replacement Improves Mobility

    MedlinePlus Videos and Cool Tools

    ... screen and open the door to informed medical care. OR Live, the vision of improving health. Hi, ... screen and open the door to informed medical care. “OR Live,” the vision of improving health. 11

  10. Comparison of Hybrid Constructs with 2-Level Artificial Disc Replacement and 2-Level Anterior Cervical Discectomy and Fusion for Surgical Reconstruction of the Cervical Spine: A Kinematic Study in Whole Cadavers

    PubMed Central

    Liu, Baoge; Zeng, Zheng; Van Hoof, Tom; Kalala, Jean Pierre; Liu, Zhenyu; Wu, Bingxuan

    2015-01-01

    Background Multi-level cervical degeneration of the spine is a common clinical pathology that is often repaired by anterior cervical discectomy and fusion (ACDF). The aim of this study was to investigate the kinematics of the cervical spine after hybrid surgery compared with 2-level ACDF. Material/Methods Five freshly frozen, unembalmed whole human cadavers were used including 3 males and 2 females with a mean age of 51±8 years. After evaluating the intact spine for range of motion (ROM), sagittal alignment and instantaneous center of rotation (ICR), each cadaver underwent 4 consecutive surgeries: 2-level artificial disc replacement (ADR) from C4 to C6 (ADR surgery); 2-level ACDF from C4 to C6 (ACDF surgery); hybrid C4–5 ACDF and C5–6 ADR (ACDF+ADR surgery); and hybrid C4–5 ADR and C5–6 ACDF (ADR+ACDF surgery). The ROM and ICR of adjacent intact segments (C3–4; C6–7), and whole sagittal alignment were revaluated. Results Two-level ACDF resulted in increased ROM at C3–4 and C6–7 compared with intact spine. ROM was significantly different to intact spine using ACDF surgery at C3–C4 and C6–C7 and ROM was increased with ACDF+ADR surgery at C6–C7 (all P<0.05). No improvement in sagittal alignment was observed with any approach. The localization of the ICR shifted upwards and anteriorly at C3–C4 after reconstruction. ICR changes at C3–C4 were greatest for ADR+ACDF surgery and were significantly different to ACDF surgery (P<0.05), but not between ADR surgery and ACDF+ADR surgery. At C6–C7, the ICR was more posterior and superior than in the intact condition. The greatest change in ICR was observed in ACDF surgery at the C6–C7 level, significantly different from the other groups (P<0.05). Conclusions For 2-level reconstruction, hybrid surgery and ADR did not alter ROM and minimally changed ICR at the adjacent-level. The type of surgery had a significant impact on the ICR location. This suggests that hybrid surgery may be a viable option for 2

  11. In vitro fertilization and artificial activation of eggs of the direct-developing anuran Eleutherodactylus coqui

    PubMed Central

    Toro, Esteban; Michael, Scott F

    2004-01-01

    Although much is known about the reproductive biology of pond-breeding frogs, there is comparatively little information about terrestrial-breeding anurans, a highly successful and diverse group. This study investigates the activation and in vitro fertilization of eggs of the Puerto Rican coqui frog obtained by hormonally induced ovulation. We report that spontaneous activation occurs in 34% of eggs, probably in response to mechanical stress during oviposition. Artificial activation, as evidenced by the slow block to polyspermy and the onset of zygote division, was elicited both by mechanical stimulation and calcium ionophore exposure in 64% and 83% of the cases, respectively. Finally, one in vitro fertilization protocol showed a 27% success rate, despite the fact that about one third of all unfertilized eggs obtained by hormone injection auto-activate. We expect these findings to aid in the conservation effort of Eleutherodactylus frogs, the largest vertebrate genus. PMID:15296510

  12. Artificial neural network and multiple regression model for nickel(II) adsorption on powdered activated carbons.

    PubMed

    Hema, M; Srinivasan, K

    2011-07-01

    Nickel removal efficiency of powered activated carbons of coconut oilcake, neem oilcake and commercial carbon was investigated by using artificial neural network. The effective parameters for the removal of nickel (%R) by adsorption process, which included the pH, contact time (T), distinctiveness of activated carbon (Cn), amount of activated carbon (Cw) and initial concentration of nickel (Co) were investigated. Levenberg-Marquardt (LM) Back-propagation algorithm is used to train the network. The network topology was optimized by varying number of hidden layer and number of neurons in hidden layer. The model was developed in terms of training; validation and testing of experimental data, the test subsets that each of them contains 60%, 20% and 20% of total experimental data, respectively. Multiple regression equation was developed for nickel adsorption system and the output was compared with both simulated and experimental outputs. Standard deviation (SD) with respect to experimental output was quite higher in the case of regression model when compared with ANN model. The obtained experimental data best fitted with the artificial neural network. PMID:23029923

  13. p38 mitogen-activated protein kinase inhibition modulates nucleus pulposus cell apoptosis in spontaneous resorption of herniated intervertebral discs: An experimental study in rats.

    PubMed

    Zhu, Yu; Liu, Jin-Tao; Yang, Li-Yan; Du, Wen-Pei; Li, Xiao-Chun; Qian, Xiang; Yu, Peng-Fei; Liu, Jian-Wen; Jiang, Hong

    2016-05-01

    The present study was performed to investigate the role of p38 mitogen‑activated protein kinase (MAPK) in the resorption of herniated intervertebral discs in 30 rats. In the non‑contained and p38 MAPK inhibition (p38i) groups, two coccygeal intervertebral discs (IVDs) were removed and wounded prior to relocation into the subcutaneous space of the skin of the back. In the contained group, the cartilage endplates maintained their integrity. Furthermore, SB203580 was injected intraperitoneally into the p38i group, whereas saline was injected into the other two groups. In the non‑contained group, the weight of the relocated IVDs decreased to a greater extent over time when compared with the contained and p38i groups. Phosphorylated p38, tumor necrosis factor‑α, and interleukin‑1β were observed to exhibit higher expression levels in the non‑contained group compared with the contained and p38i groups, at weeks 1 and 4 post‑surgery. The expression level of caspase‑3 and the densities of apoptotic disc cells were significantly higher in the non‑contained group compared with the contained and p38i groups at 4 weeks post‑surgery. In conclusion, p38 MAPK induces apoptosis in IVDs, while also accelerating the resorption of the relocated IVDs. Thus, p38 MAPK may be important in spontaneous resorption of IVDs. PMID:27035219

  14. Crocin exerts anti-inflammatory and anti-catabolic effects on rat intervertebral discs by suppressing the activation of JNK

    PubMed Central

    LI, KANG; LI, YAN; MA, ZHENJIANG; ZHAO, JIE

    2015-01-01

    As intervertebral disc (IVD) degeneration has been proven to contribute to low back pain (LBP), drug treatment aiming at attenuating IVD degeneration may prove to be benefiical. Crocin, a bioactive component of saffron, has been found to exert anti-inflammatory effects on cartilage. In the present study, the anti-inflammatory and anti-catabolic effects of crocin on rat IVDs were analyzed in vitro and ex vivo. Nucleus pulposus (NP) cells were isolated from the lumbar IVDs of Sprague-Dawley rats. The NP cells were first treated with various concentrations of crocin, and then stimulated with lipopolysaccharide (LPS) to induce inflammation. Subsequently, RT-qPCR and enzyme-linked immunosorbent assay were carried out to measure the expression levels of catabolic enzymes, pro-inflammatory factors and the components of the extracellular matrix (ECM). In addition, western blot analysis was also used to investigate the related signaling pathways. The whole spinal motion segment (vertebra-IVD-vertebra section) of the rats was isolated and cultured in the presence or absence of LPS and crocin for 7 days. The ex vivo effects of crocin on the ECM of the IVD structures were determined by histological and biochemical analysis. In vitro, crocin significantly inhibited the LPS-induced overexpression of catabolic enzymes [matrix metalloproteinase (MMP)-1, MMP-3, MMP-13, a disintegrin-like and metalloprotease (reprolysin type) with thrombospondin type 1 motif (ADAMTS)-4 and ADAMTS-5], pro-inflammatory factors [interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6 and inducible nitric oxide synthase (iNOS)] and Toll-like receptor (TLR)-2 in a concentration-dependent manner. Notably, crocin partly prevented the downregulation of aggrecan and type II collagen (collagen-II). Moreover, crocin suppressed the LPS-induced activation of the mitogen-activated protein kinase (MAPK) pathway by inhibiting the phosphorylation of c-Jun N-terminal kinase (JNK). Ex vivo experiments demonstrated

  15. Crocin exerts anti-inflammatory and anti-catabolic effects on rat intervertebral discs by suppressing the activation of JNK.

    PubMed

    Li, Kang; Li, Yan; Ma, Zhenjiang; Zhao, Jie

    2015-11-01

    As intervertebral disc (IVD) degeneration has been proven to contribute to low back pain (LBP), drug treatment aiming at attenuating IVD degeneration may prove to be benefiical. Crocin, a bioactive component of saffron, has been found to exert anti-inflammatory effects on cartilage. In the present study, the anti-inflammatory and anti-catabolic effects of crocin on rat IVDs were analyzed in vitro and ex vivo. Nucleus pulposus (NP) cells were isolated from the lumbar IVDs of Sprague-Dawley rats. The NP cells were first treated with various concentrations of crocin, and then stimulated with lipopolysaccharide (LPS) to induce inflammation. Subsequently, RT-qPCR and enzyme-linked immunosorbent assay were carried out to measure the expression levels of catabolic enzymes, pro-inflammatory factors and the components of the extracellular matrix (ECM). In addition, western blot analysis was also used to investigate the related signaling pathways. The whole spinal motion segment (vertebra-IVD-vertebra section) of the rats was isolated and cultured in the presence or absence of LPS and crocin for 7 days. The ex vivo effects of crocin on the ECM of the IVD structures were determined by histological and biochemical analysis. In vitro, crocin significantly inhibited the LPS-induced overexpression of catabolic enzymes [matrix metalloproteinase (MMP)-1, MMP-3, MMP-13, a disintegrin-like and metalloprotease (reprolysin type) with thrombospondin type 1 motif (ADAMTS)-4 and ADAMTS‑5], pro-inflammatory factors [interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6 and inducible nitric oxide synthase (iNOS)] and Toll-like receptor (TLR)‑2 in a concentration-dependent manner. Notably, crocin partly prevented the downregulation of aggrecan and type II collagen (collagen‑II). Moreover, crocin suppressed the LPS-induced activation of the mitogen-activated protein kinase (MAPK) pathway by inhibiting the phosphorylation of c-Jun N-terminal kinase (JNK). Ex vivo experiments

  16. Urea elimination using a cold activated-carbon artificial tubulus for hemofiltration.

    PubMed

    Lehmann, H D; Marten, R; Fahrner, I; Gullberg, C A

    1981-11-01

    Urea adsorption on active carbon is reversible and temperature-dependent. Urea adsorption isotherms of different carbons were determined at 0 degrees C and 65 degrees C within the equilibrium concentration range of 1.0-3.4 gm/L. At low urea concentrations considerable differences (3.4-13.0 gm/kg carbon at concentrations of 1.0 gm/L) were found between different types of activated carbon. The overall internal surface area was of minor importance compared to the pore size distribution. Adsorbing at low temperature, desorbing at high temperature, and flushing the carbon adsorber with a limited volume of the liquid to be purified yielded an "artificial urine." Compared to the original urea concentration of the filtrate, this "artificial urine" had an increased urea concentration. From a 36-liter volume containing 90 grams urea dissolved in saline, 18 liters were recirculated at a flow rate of 100 ml/min. The influence of adsorption and desorption time intervals was evaluated. After one to one and a half hours the carbon was saturated with urea. After saturation, about 1.4 grams urea were eliminated per cycle. In the "artificial urine" urea concentrations of up to 4.5 gm/L were found when the original solution contained only 2.5 gm/L. In the "patient" volume the urea concentration decreased from 2.5 gm/L to 1.9-2.1 gm/L. Within three hours a total of 22 grams of urea was removed by 3 x 120 grams activated carbon corresponding to removal of 50% of the urea passing the "artificial tubulus." The advantage of this system is that after priming, no additional physiological solution would be necessary. The necessity of excessive safety controls, additional electrolyte adjustment, energy demand in the form of direct current, and great amounts of waste in solid form lead to the conclusion that for intermittent hemofiltration treatment, commercially produced and controlled infusion solution is preferable. PMID:7325876

  17. METAMORPHOSE VI - the Virtual Institute for artificial electromagnetic materials and metamaterials: origin, mission, and activities

    NASA Astrophysics Data System (ADS)

    Bilotti, Filiberto; Rockstuhl, Carsten; Schuchinsky, Alex; Tretyakov, Sergei

    2014-06-01

    In this paper, we outline the background, mission, and activities of the Virtual Institute for Artificial Electromagnetic Materials and Metamaterials (METAMORPHOSE VI). This international association, founded in the framework of the FP-6 Network of Excellence METAMORPHOSE, aims at promoting and developing research, training, and dissemination activities in the emerging and highly dynamic field of advanced electromagnetic materials and metamaterials at both European and International levels. More than 300 researchers are currently associated with the METAMORPHOSE VI which networks them together in a learnt society. After a brief description of the association and its mission, we present an overview of the activities developed by the METAMORPHOSE VI, with a particular emphasis on the coordination of the European Doctoral Program on Metamaterials (EUPROMETA) and the organization of the International Congress on Advanced Electromagnetic Materials in Microwaves and Optics - metamaterials congress.

  18. Measurement of the activity of an artificial neutrino source based on {sup 37}Ar

    SciTech Connect

    Abdurashitov, D. N.; Veretenkin, E. P.; Gavrin, V. N.; Gorbachev, V. V.; Ibragimova, T. V.; Kalikhov, A. V.; Mirmov, I. N. Shikhin, A. A.; Yants, V. E.; Barsanov, V. I.; Dzhanelidze, A. A.; Zlokazov, S. B.; Markov, S. Yu.; Shakirov, Z. N.; Cleveland, B. T.

    2007-02-15

    The activity of an artificial neutrino source based on {sup 37}Ar was measured by a specially developed method of directly counting {sup 37}Ar decays in a proportional counter. This source was used to irradiate the target of the SAGE radiochemical gallium-germanium neutrino telescope at the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences, Moscow), whereupon the measurements were performed at the Institute of Reactor Materials (Zarechny, Sverdlovsk oblast, Russia). The method used to prepare gaseous samples for measurements in proportional counters and the counting procedure are described. The measured activity of the {sup 37}Ar neutrino source is 405.1 {+-} 3.7 kCi (corrected for decays that occurred within the period between the instant of activity measurement and the commencement of the irradiation of Ga target at 04:00 Moscow time, 30.04.2004)

  19. Disc cell senescence in intervertebral disc degeneration: Causes and molecular pathways

    PubMed Central

    Feng, Chencheng; Liu, Huan; Yang, Minghui; Zhang, Yang; Huang, Bo; Zhou, Yue

    2016-01-01

    ABSTRACT The accumulation of senescent disc cells in degenerative intervertebral disc (IVD) suggests the detrimental roles of cell senescence in the pathogenesis of intervertebral disc degeneration (IDD). Disc cell senescence decreased the number of functional cells in IVD. Moreover, the senescent disc cells were supposed to accelerate the process of IDD via their aberrant paracrine effects by which senescent cells cause the senescence of neighboring cells and enhance the matrix catabolism and inflammation in IVD. Thus, anti-senescence has been proposed as a novel therapeutic target for IDD. However, the development of anti-senescence therapy is based on our understanding of the molecular mechanism of disc cell senescence. In this review, we focused on the molecular mechanism of disc cell senescence, including the causes and various molecular pathways. We found that, during the process of IDD, age-related damages together with degenerative external stimuli activated both p53-p21-Rb and p16-Rb pathways to induce disc cell senescence. Meanwhile, disc cell senescence was regulated by multiple signaling pathways, suggesting the complex regulating network of disc cell senescence. To understand the mechanism of disc cell senescence better contributes to developing the anti-senescence-based therapies for IDD. PMID:27192096

  20. Active Path Selection of Fluid Microcapsules in Artificial Blood Vessel by Acoustic Radiation Force

    NASA Astrophysics Data System (ADS)

    Masuda, Kohji; Muramatsu, Yusuke; Ueda, Sawami; Nakamoto, Ryusuke; Nakayashiki, Yusuke; Ishihara, Ken

    2009-07-01

    Micrometer-sized microcapsules collapse upon exposure to ultrasound. Use of this phenomenon for a drug delivery system (DDS), not only for local delivery of medication but also for gene therapy, should be possible. However, enhancing the efficiency of medication is limited because capsules in suspension diffuse in the human body after injection, since the motion of capsules in blood flow cannot be controlled. To control the behavior of microcapsules, acoustic radiation force was introduced. We detected local changes in microcapsule density by producing acoustic radiation force in an artificial blood vessel. Furthermore, we theoretically estimated the conditions required for active path selection of capsules at a bifurcation point in the artificial blood vessel. We observed the difference in capsule density at both in the bifurcation point and in alternative paths downstream of the bifurcation point for different acoustic radiation forces. Comparing the experimental results with those obtained theoretically, the conditions for active path selection were calculated from the acoustic radiation force and fluid resistance of the capsules. The possibility of controlling capsule flow towards a specific point in a blood vessel was demonstrated.

  1. Ligand Biological Activity Predictions Using Fingerprint-Based Artificial Neural Networks (FANN-QSAR)

    PubMed Central

    Myint, Kyaw Z.; Xie, Xiang-Qun

    2015-01-01

    This chapter focuses on the fingerprint-based artificial neural networks QSAR (FANN-QSAR) approach to predict biological activities of structurally diverse compounds. Three types of fingerprints, namely ECFP6, FP2, and MACCS, were used as inputs to train the FANN-QSAR models. The results were benchmarked against known 2D and 3D QSAR methods, and the derived models were used to predict cannabinoid (CB) ligand binding activities as a case study. In addition, the FANN-QSAR model was used as a virtual screening tool to search a large NCI compound database for lead cannabinoid compounds. We discovered several compounds with good CB2 binding affinities ranging from 6.70 nM to 3.75 μM. The studies proved that the FANN-QSAR method is a useful approach to predict bioactivities or properties of ligands and to find novel lead compounds for drug discovery research. PMID:25502380

  2. Anti-glycated activity prediction of polysaccharides from two guava fruits using artificial neural networks.

    PubMed

    Yan, Chunyan; Lee, Jinsheng; Kong, Fansheng; Zhang, Dezhi

    2013-10-15

    High-efficiency ultrasonic treatment was used to extract the polysaccharides of Psidium guajava (PPG) and Psidium littorale (PPL). The aims of this study were to compare polysaccharide activities from these two guavas, as well as to investigate the relationship between ultrasonic conditions and anti-glycated activity. A mathematical model of anti-glycated activity was constructed with the artificial neural network (ANN) toolbox of MATLAB software. Response surface plots showed the correlation between ultrasonic conditions and bioactivity. The optimal ultrasonic conditions of PPL for the highest anti-glycated activity were predicted to be 256 W, 60 °C, and 12 min, and the predicted activity was 42.2%. The predicted highest anti-glycated activity of PPG was 27.2% under its optimal predicted ultrasonic condition. The experimental result showed that PPG and PPL possessed anti-glycated and antioxidant activities, and those of PPL were greater. The experimental data also indicated that ANN had good prediction and optimization capability. PMID:23987324

  3. Video Discs in Education.

    ERIC Educational Resources Information Center

    Barker, Philip

    1986-01-01

    This discussion of the use of images in learning processes focuses on recent developments in optical storage disc technology, particularly compact disc read-only (CD-ROM) and optical video discs. Interactive video systems and user interfaces are described, and applications in education and industry in the United Kingdom are reviewed. (Author/LRW)

  4. Turbine disc sealing assembly

    DOEpatents

    Diakunchak, Ihor S.

    2013-03-05

    A disc seal assembly for use in a turbine engine. The disc seal assembly includes a plurality of outwardly extending sealing flange members that define a plurality of fluid pockets. The sealing flange members define a labyrinth flow path therebetween to limit leakage between a hot gas path and a disc cavity in the turbine engine.

  5. Targeting the annulus fibrosus of the intervertebral disc: Col1a2-Cre(ER)T mice show specific activity of Cre recombinase in the outer annulus fibrosus.

    PubMed

    Bedore, Jake; Quesnel, Katherine; Quinonez, Diana; Séguin, Cheryle A; Leask, Andrew

    2016-06-01

    Degeneration of the intervertebral disc (IVD) is a major underlying contributor to back pain-the single leading cause of disability worldwide. However, we possess a limited understanding of the etiology underlying IVD degeneration. To date, there are a limited number of mouse models that have been used to target proteins in specific compartments of the IVD to explore their functions in disc development, homeostasis and disease. Furthermore, the majority of reports exploring the composition and function of the outer encapsulating annulus fibrosus (AF) of the IVD have considered it as one tissue, without considering the numerous structural and functional differences existing between the inner and outer AF. In addition, no mouse models have yet been reported that enable specific targeting of genes within the outer AF. In the current report, we discuss these issues and demonstrate the localized activity of Cre recombinase in the IVD of Col1a2-Cre(ER)T;ROSA26mTmG mice possessing a tamoxifen-dependent Cre recombinase driven by a Cola2 promoter and distal enhancer and the mTmG fluorescent reporter. Following tamoxifen injection of 3-week-old Col1a2-Cre(ER)T;ROSA26mTmG mice, we show Cre activity specifically in the outer AF of the IVD, as indicated by expression of the GFP reporter. Thus, Col1a2-Cre(ER)T;ROSA26mTmG mice may prove to be a valuable tool in delineating the function of proteins in this unique compartment of the IVD, and in further exploring the compositional differences between the inner and outer AF in disc homeostasis, aging and disease. PMID:27173473

  6. Gender specific changes in cortical activation patterns during exposure to artificial gravity

    NASA Astrophysics Data System (ADS)

    Schneider, Stefan; Robinson, Ryan; Smith, Craig; von der Wiesche, Melanie; Goswami, Nandu

    2014-11-01

    Keeping astronauts healthy during long duration spaceflight remains a challenge. Artificial gravity (AG) generated by a short arm human centrifuges (SAHC) is proposed as the next generation of integrated countermeasure devices that will allow human beings to safely spend extended durations in space, although comparatively little is known about any psychological side effects of AG on brain function. 16 participants (8 male and 8 female, GENDER) were exposed to 10 min at a baseline gravitational load (G-Load) of +.03 Gz, then 10 min at +.6 Gz for females and +.8 Gz for males, before being exposed to increasing levels of AG in a stepped manner by increasing the acceleration by +.1 Gz every 3 min until showing signs of pre-syncope. EEG recordings were taken of brain activity during 2 min time periods at each AG level. Analysing the results of the mixed total population of participants by two way ANOVA, a significant effect of centrifugation on alpha and beta activity was found (p<.01). Furthermore results revealed a significant interaction between G-LOAD and GENDER alpha-activity (p<.01), but not for beta-activity. Although the increase in alpha and beta activity with G-LOAD does not reflect a general model of cortical arousal and therefore cannot support previous findings reporting that AG may be a cognitively arousing environment, the gender specific responses identified in this study may have wider implications for EEG and AG research.

  7. Optical Disc Applications in Libraries.

    ERIC Educational Resources Information Center

    Andre, Pamela Q. J.

    1989-01-01

    Discusses a variety of library applications of optical disc storage technology, including CD-ROM, digital videodisc, and WORM. Research and development projects at the Library of Congress, National Library of Medicine, and National Agricultural Library are described, products offered by library networks are reviewed, and activities in academic and…

  8. Active wound dressing with artificial capillaries for temporary wound irrigation and skin cell supply.

    PubMed

    Plettig, Jörn; Johnen, Christa M; Bräutigam, Kirsten; Zeilinger, Katrin; Borneman, Reinhard; Gerlach, Jörg C

    2012-04-01

    Medical treatment of burns and chronic wounds remains a challenge. We discussed a therapy concept that combines skin cell spray transplantation with a novel wound dressing based on artificial hollow fiber membrane capillaries. In skin cell-based therapy development, autologous skin progenitor cells are isolated from a healthy skin area and sprayed onto the wound. A medical device was introduced that uses perfused capillaries, known from clinical plasma separation, as a temporarily applied extracorporeal wound capillary bed. The functions of the dressing are comparable with those of dialysis; the capillaries, however, are applied externally onto the wound. Perfusion with a clinical peripheral nutrition and buffer solution can provide wound irrigation, wound debris removal, cell nutrition, pH regulation, and electrolyte balance while potentially serving to address delivery of regenerative factors and antibiosis. An innovative active skin wound dressing that provides cell support and stimulates regeneration by wound irrigation is discussed. PMID:22074237

  9. Production and removal of superoxide anion radical by artificial metalloenzymes and redox-active metals

    PubMed Central

    Kawano, Tomonori; Kagenishi, Tomoko; Kadono, Takashi; Bouteau, François; Hiramatsu, Takuya; Lin, Cun; Tanaka, Kenichiro; Tanaka, Licca; Mancuso, Stefano; Uezu, Kazuya; Okobira, Tadashi; Furukawa, Hiroka; Iwase, Junichiro; Inokuchi, Reina; Baluška, Frantisek; Yokawa, Ken

    2015-01-01

    Generation of reactive oxygen species is useful for various medical, engineering and agricultural purposes. These include clinical modulation of immunological mechanism, enhanced degradation of organic compounds released to the environments, removal of microorganisms for the hygienic purpose, and agricultural pest control; both directly acting against pathogenic microorganisms and indirectly via stimulation of plant defense mechanism represented by systemic acquired resistance and hypersensitive response. By aiming to develop a novel classes of artificial redox-active biocatalysts involved in production and/or removal of superoxide anion radicals, recent attempts for understanding and modification of natural catalytic proteins and functional DNA sequences of mammalian and plant origins are covered in this review article. PMID:27066179

  10. Production and removal of superoxide anion radical by artificial metalloenzymes and redox-active metals.

    PubMed

    Kawano, Tomonori; Kagenishi, Tomoko; Kadono, Takashi; Bouteau, François; Hiramatsu, Takuya; Lin, Cun; Tanaka, Kenichiro; Tanaka, Licca; Mancuso, Stefano; Uezu, Kazuya; Okobira, Tadashi; Furukawa, Hiroka; Iwase, Junichiro; Inokuchi, Reina; Baluška, Frantisek; Yokawa, Ken

    2015-01-01

    Generation of reactive oxygen species is useful for various medical, engineering and agricultural purposes. These include clinical modulation of immunological mechanism, enhanced degradation of organic compounds released to the environments, removal of microorganisms for the hygienic purpose, and agricultural pest control; both directly acting against pathogenic microorganisms and indirectly via stimulation of plant defense mechanism represented by systemic acquired resistance and hypersensitive response. By aiming to develop a novel classes of artificial redox-active biocatalysts involved in production and/or removal of superoxide anion radicals, recent attempts for understanding and modification of natural catalytic proteins and functional DNA sequences of mammalian and plant origins are covered in this review article. PMID:27066179

  11. Classification of Physical Activity: Information to Artificial Pancreas Control Systems in Real Time.

    PubMed

    Turksoy, Kamuran; Paulino, Thiago Marques Luz; Zaharieva, Dessi P; Yavelberg, Loren; Jamnik, Veronica; Riddell, Michael C; Cinar, Ali

    2015-11-01

    Physical activity has a wide range of effects on glucose concentrations in type 1 diabetes (T1D) depending on the type (ie, aerobic, anaerobic, mixed) and duration of activity performed. This variability in glucose responses to physical activity makes the development of artificial pancreas (AP) systems challenging. Automatic detection of exercise type and intensity, and its classification as aerobic or anaerobic would provide valuable information to AP control algorithms. This can be achieved by using a multivariable AP approach where biometric variables are measured and reported to the AP at high frequency. We developed a classification system that identifies, in real time, the exercise intensity and its reliance on aerobic or anaerobic metabolism and tested this approach using clinical data collected from 5 persons with T1D and 3 individuals without T1D in a controlled laboratory setting using a variety of common types of physical activity. The classifier had an average sensitivity of 98.7% for physiological data collected over a range of exercise modalities and intensities in these subjects. The classifier will be added as a new module to the integrated multivariable adaptive AP system to enable the detection of aerobic and anaerobic exercise for enhancing the accuracy of insulin infusion strategies during and after exercise. PMID:26443291

  12. The Effect of GCSB-5 a New Herbal Medicine on Changes in Pain Behavior and Neuroglial Activation in a Rat Model of Lumbar Disc Herniation

    PubMed Central

    Cho, Hee Kyung; Kim, So-Yeon; Choi, Mi Jung; Baek, Seung Ok; Kwak, Sang Gyu

    2016-01-01

    Objective Lumbar disc herniation can induce sciatica by mechanical compression and/or chemical irritation. The aim of this study was to compare the effects of GCSB-5 (Shinbaro®) and NSAIDs on pain-related behavior and on the expressions of microglia, astrocytes, CGRP, TRPV1, IL-6, and CX3CL1 in a rat model of lumbar disc herniation. Methods 112 male Sprague-Dawley rats underwent implantation of nucleus pulposus to a dorsal root ganglion (DRG). Rats were divided into five groups as follows; a saline group (the vehicle control group) (n=27), a 10 mg/kg aceclofenac group (the aceclofenac group) (n=22), and 100, 300 or 600 mg/kg GCSB-5 groups (the GCSB-5 100, 300, or 600 groups) (n=21 for each group). Rats were tested for mechanical allodynia at 3 days after surgery and at 1 day, 3 days, 7 days, 14 days, 21 days, 28 days, 35 days, 42 days, 49 days, and 56 days after treatment commencement. Immunohistochemical staining of microglia (Iba1), astrocytes (GFAP), CGRP, and TRPV1, and PCR for IL-6 and CX3CL1 were performed on spinal dorsal horns and DRGs at 56 days after medication commencement. Results After 56 days of GCSB-5 300 administration, mechanical withdrawal thresholds were significantly increased (p<0.05), and immunohisto-chemical expressions of Iba1, GFAP, CGRP, and TRPV1 were reduced than other groups, but this difference was not statistically significant. Conclusion These results indicate GCSB-5 reduces mechanical allodynia and downregulates neuroglial activity and the expressions of CGRP and TRPV1 in the spinal segments of a rat model of lumbar disc herniation. PMID:26962414

  13. Blu-ray Technology-Based Quantitative Assays for Cardiac Markers: From Disc Activation to Multiplex Detection.

    PubMed

    Weng, Samuel; Li, Xiaochun; Niu, Michelle; Ge, Bixia; Yu, Hua-Zhong

    2016-07-01

    Acute myocardial infarction (AMI) is the leading cause of mortality and morbidity globally. To reduce the number of mortalities, reliable and rapid point-of-care (POC) diagnosis of AMI is extremely critical. We herein present a Blu-ray technology-based assay platform for multiplex cardiac biomarker detection; not only off-the-shelf Blu-ray discs (BDs) were adapted as substrates to prepare standard immunoassays and DNA aptamer/antibody hybrid assays for the three key cardiac marker proteins (myoglobin, troponin I, and C-creative protein) but also an unmodified optical drive was directly employed to read the assay results digitally. In particular, we have shown that all three cardiac markers can be quantitated in their respective physiological ranges of interest, and the detection limits achieved are comparable with conventional enzyme-linked immunosorbent assay (ELISA) kits. The Blu-ray assay platform was further validated by measuring real-world samples and establishing a linear correlation with the simultaneously obtained ELISA data. Without the need to modify either the hardware (Blu-ray discs and optical drives) or the software driver, this assay-on-a-BD technique promises to be a low-cost user-friendly quantitative tool for on-site chemical analysis and POC medical diagnosis. PMID:27268387

  14. Lumbar disc replacement in adolescents: An initial experience in two cases

    PubMed Central

    Kasliwal, Manish K.; Deutsch, Harel

    2012-01-01

    Management of painful lumbar disc degeneration is one of the most common conditions treated by spine surgeons. Several recent prospective multicenter trials have demonstrated the effectiveness of artificial lumbar disc replacement in treating discogenic lower back pain. Though data on the safety and effectiveness has gradually been accumulated in adults, there is a lack of published data on the effectiveness and feasibility of lumbar artificial disc replacement in adolescents. The authors share their initial clinical experience with lumbar disc replacement in a couple of adolescents. PMID:23248694

  15. Hydrodynamic instability in warped astrophysical discs

    NASA Astrophysics Data System (ADS)

    Ogilvie, Gordon I.; Latter, Henrik N.

    2013-08-01

    Warped astrophysical discs are usually treated as laminar viscous flows, which have anomalous properties when the disc is nearly Keplerian and the viscosity is small: fast horizontal shearing motions and large torques are generated, which cause the warp to evolve rapidly, in some cases at a rate that is inversely proportional to the viscosity. However, these flows are often subject to a linear hydrodynamic instability, which may produce small-scale turbulence and modify the large-scale dynamics of the disc. We use a warped shearing sheet to compute the oscillatory laminar flows in a warped disc and to analyse their linear stability by the Floquet method. We find widespread hydrodynamic instability deriving from the parametric resonance of inertial waves. Even very small, unobservable warps in nearly Keplerian discs of low viscosity can be expected to generate hydrodynamic turbulence, or at least wave activity, by this mechanism.

  16. Hemoglobin–Albumin Cluster Incorporating a Pt Nanoparticle: Artificial O2 Carrier with Antioxidant Activities

    PubMed Central

    Hosaka, Hitomi; Haruki, Risa; Yamada, Kana; Böttcher, Christoph; Komatsu, Teruyuki

    2014-01-01

    A covalent core–shell structured protein cluster composed of hemoglobin (Hb) at the center and human serum albumins (HSA) at the periphery, Hb-HSAm, is an artificial O2 carrier that can function as a red blood cell substitute. Here we described the preparation of a novel Hb-HSA3 cluster with antioxidant activities and its O2 complex stable in aqueous H2O2 solution. We used an approach of incorporating a Pt nanoparticle (PtNP) into the exterior HSA unit of the cluster. A citrate reduced PtNP (1.8 nm diameter) was bound tightly within the cleft of free HSA with a binding constant (K) of 1.1×107 M−1, generating a stable HSA-PtNP complex. This platinated protein showed high catalytic activities for dismutations of superoxide radical anions (O2•–) and hydrogen peroxide (H2O2), i.e., superoxide dismutase and catalase activities. Also, Hb-HSA3 captured PtNP into the external albumin unit (K = 1.1×107 M−1), yielding an Hb-HSA3(PtNP) cluster. The association of PtNP caused no alteration of the protein surface net charge and O2 binding affinity. The peripheral HSA-PtNP shell prevents oxidation of the core Hb, which enables the formation of an extremely stable O2 complex, even in H2O2 solution. PMID:25310133

  17. Fusion-Triggered Switching of Enzymatic Activity on an Artificial Cell Membrane

    PubMed Central

    Mukai, Masaru; Sasaki, Yoshihiro; Kikuchi, Jun-ichi

    2012-01-01

    A nanosensory membrane device was constructed for detecting liposome fusion through changes in an enzymatic activity. Inspired by a biological signal transduction system, the device design involved functionalized liposomal membranes prepared by self-assembly of the following molecular components: a synthetic peptide lipid and a phospholipid as matrix membrane components, a Schiff's base of pyridoxal 5′-phosphate with phosphatidylethanolamine as a thermo-responsive artificial receptor, NADH-dependent L-lactate dehydrogenase as a signal amplifier, and Cu2+ ion as a signal mediator between the receptor and enzyme. The enzymatic activity of the membrane device was adjustable by changing the matrix lipid composition, reflecting the thermotropic phase transition behavior of the lipid membranes, which in turn controlled receptor binding affinity toward the enzyme-inhibiting mediator species. When an effective fusogen anionic polymer was added to these cationic liposomes, membrane fusion occurred, and the functionalized liposomal membranes responded with changes in enzymatic activity, thus serving as an effective nanosensory device for liposome fusion detection. PMID:22778625

  18. Artificial sweeteners and salts producing a metallic taste sensation activate TRPV1 receptors.

    PubMed

    Riera, Céline E; Vogel, Horst; Simon, Sidney A; le Coutre, Johannes

    2007-08-01

    Throughout the world many people use artificial sweeteners (AS) for the purpose of reducing caloric intake. The most prominently used of these molecules include saccharin, aspartame (Nutrasweet), acesulfame-K, and cyclamate. Despite the caloric advantage they provide, one key concern in their use is their aversive aftertaste that has been characterized on a sensory level as bitter and/or metallic. Recently, it has been shown that the activation of particular T2R bitter taste receptors is partially involved with the bitter aftertaste sensation of saccharin and acesulfame-K. To more fully understand the biology behind these phenomena we have addressed the question of whether AS could stimulate transient receptor potential vanilloid-1 (TRPV1) receptors, as these receptors are activated by a large range of structurally different chemicals. Moreover, TRPV1 receptors and/or their variants are found in taste receptor cells and in nerve terminals throughout the oral cavity. Hence, TRPV1 activation could be involved in the AS aftertaste or even contribute to the poorly understood metallic taste sensation. Using Ca(2+) imaging on TRPV1 receptors heterologously expressed in the human embryonic kidney (HEK) 293 cells and on dissociated primary sensory neurons, we find that in both systems, AS activate TRPV1 receptors, and, moreover, they sensitize these channels to acid and heat. We also found that TRPV1 receptors are activated by CuSO(4), ZnSO(4), and FeSO(4), three salts known to produce a metallic taste sensation. In summary, our results identify a novel group of compounds that activate TRPV1 and, consequently, provide a molecular mechanism that may account for off tastes of sweeteners and metallic tasting salts. PMID:17567713

  19. Design of Surface-Active Artificial Enzyme Particles to Stabilize Pickering Emulsions for High-Performance Biphasic Biocatalysis.

    PubMed

    Chen, Zhaowei; Zhao, Chuanqi; Ju, Enguo; Ji, Haiwei; Ren, Jinsong; Binks, Bernard P; Qu, Xiaogang

    2016-02-24

    Surface-active artificial enzymes (SAEs) are designed and constructed by a general and novel strategy. These SAEs can simultaneously stabilize Pickering emulsions and catalyze biphasic biotransformation with superior enzymatic stability and good re-usability; for example, for the interfacial conversion of hydrophobic p-nitrophenyl butyrate into yellow water-soluble p-nitrophenolate catalyzed by esterase-mimic SAE. PMID:26684519

  20. An artificial HSE promoter for efficient and selective detection of heat shock pathway activity.

    PubMed

    Ortner, Viktoria; Ludwig, Alfred; Riegel, Elisabeth; Dunzinger, Sarah; Czerny, Thomas

    2015-03-01

    Detection of cellular stress is of major importance for the survival of cells. During evolution, a network of stress pathways developed, with the heat shock (HS) response playing a major role. The key transcription factor mediating HS signalling activity in mammalian cells is the HS factor HSF1. When activated it binds to the heat shock elements (HSE) in the promoters of target genes like heat shock protein (HSP) genes. They are induced by HSF1 but in addition they integrate multiple signals from different stress pathways. Here, we developed an artificial promoter consisting only of HSEs and therefore selectively reacting to HSF-mediated pathway activation. The promoter is highly inducible but has an extreme low basal level. Direct comparison with the HSPA1A promoter activity indicates that heat-dependent expression can be fully recapitulated by isolated HSEs in human cells. Using this sensitive reporter, we measured the HS response for different temperatures and exposure times. In particular, long heat induction times of 1 or 2 h were compared with short heat durations down to 1 min, conditions typical for burn injuries. We found similar responses to both long and short heat durations but at completely different temperatures. Exposure times of 2 h result in pathway activation at 41 to 44 °C, whereas heat pulses of 1 min lead to a maximum HS response between 47 and 50 °C. The results suggest that the HS response is initiated by a combination of temperature and exposure time but not by a certain threshold temperature. PMID:25168173

  1. Photodynamic activity of the boronated chlorin e6 amide in artificial and cellular membranes.

    PubMed

    Antonenko, Yuri N; Kotova, Elena A; Omarova, Elena O; Rokitskaya, Tatyana I; Ol'shevskaya, Valentina A; Kalinin, Valery N; Nikitina, Roza G; Osipchuk, Julia S; Kaplan, Mikhail A; Ramonova, Alla A; Moisenovich, Mikhail M; Agapov, Igor I; Kirpichnikov, Mikhail P

    2014-03-01

    Photodynamic tumor-destroying activity of the boronated chlorin e6 derivative BACE (chlorin e6 13(1)-N-{2-[N-(1-carba-closo-dodecaboran-1-yl)methyl]aminoethyl}amide-15(2), 17(3)-dimethyl ester), previously described in Moisenovich et al. (2010) PLoS ONE 5(9) e12717, was shown here to be enormously higher than that of unsubstituted chlorin e6, being supported by the data on much higher photocytotoxicity of BACE in M-1 sarcoma cell culture. To validate membrane damaging effect as the basis of the enhanced tumoricidal activity, BACE was compared with unsubstituted chlorin e6 in the potency to photosensitize dye leakage from liposomes, transbilayer lipid flip-flop, inactivation of gramicidin A ionic channels in planar lipid membranes and erythrocyte hemolysis. In all the models comprising artificial and cellular membranes, the photodynamic effect of BACE exceeded that of chlorin e6. BACE substantially differed from chlorin e6 in the affinity to liposomes and erythrocytes, as monitored by fluorescence spectroscopy, flow cytometry and centrifugation. The results support the key role of membrane binding in the photodynamic effect of the boronated chlorin e6 amide. PMID:24287152

  2. Molecular Fingerprint-based Artificial Neural Networks QSAR for Ligand Biological Activity Predictions

    PubMed Central

    Myint, Kyaw-Zeyar; Wang, Lirong; Tong, Qin; Xie, Xiang-Qun

    2012-01-01

    In this manuscript, we have reported a novel 2D fingerprint-based artificial neural network QSAR (FANN-QSAR) method in order to effectively predict biological activities of structurally diverse chemical ligands. Three different types of fingerprints, namely ECFP6, FP2 and MACCS, were used in FANN-QSAR algorithm development, and FANN-QSAR models were compared to known 3D and 2D QSAR methods using five data sets previously reported. In addition, the derived models were used to predict GPCR cannabinoid ligand binding affinities using our manually curated cannabinoid ligand database containing 1699 structurally diverse compounds with reported cannabinoid receptor subtype CB2 activities. To demonstrate its useful applications, the established FANN-QSAR algorithm was used as a virtual screening tool to search a large NCI compound database for lead cannabinoid compounds and we have discovered several compounds with good CB2 binding affinities ranging from 6.70 nM to 3.75 μM. To the best of our knowledge, this is the first report for a fingerprint-based neural network approach validated with a successful virtual screening application in identifying lead compounds. The studies proved that the FANN-QSAR method is a useful approach to predict bioactivities or properties of ligands and to find novel lead compounds for drug discovery research. PMID:22937990

  3. Artificial activation of bovine and equine oocytes with cycloheximide, roscovitine, strontium, or 6-dimethylaminopurine in low or high calcium concentrations.

    PubMed

    Fernandes, Claudia Barbosa; Devito, Liani Gasparini; Martins, Lilian Rigatto; Blanco, Ieda Dala Pria; de Lima Neto, João Ferreria; Tsuribe, Patricia Myakawa; Gonçalves, Camila Gabriela Pereria; da Cruz Landim-Alvarenga, Fernanda

    2014-08-01

    Knowledge on parthenogenetic activation of oocytes is important to improve the efficiency of nuclear transfer (NT) and intracytoplasmic sperm injection (ICSI) because artificial activation of oocyte (AOA) is an essential step to achieve embryo production. Although different procedures for AOA have been established, the efficiency of in vitro production of embryos remains low, especially in equines and Bos taurus bovines. In an attempt to improve the techniques of NT and ICSI in bovine and equine species, we tested different combinations of drugs that had different mechanisms of action for the parthenogenetic activation of oocytes in these animals. The oocytes were collected, in vitro matured for 24 to 30 h and activated artificially, in the presence of low or high concentrations of calcium, with combinations of calcium ionophore (ionomycin) with cycloheximide, roscovitine, strontium, or 6-dimethylaminopurine (6-DMAP). For assessment of activation rates, oocytes were stained with Hoechst 33342 and observed under an inverted microscope. We showed that all combinations of drugs were equally efficient in activating bovine oocytes, with the best results obtained when high concentrations of calcium were adopted. For equine oocytes, high concentrations of calcium were not beneficial for the parthenogenetic activation and the combination of ionomycin with either 6-DMAP or roscovitine was effective in inducing artificial activation of oocytes. We believe that our preliminary findings provide some clues for the development of a better AOA protocol to be used with these species. PMID:23340077

  4. Design concepts in lumbar total disc arthroplasty

    PubMed Central

    Bellini, Chiara M.; Zweig, Thomas; Ferguson, Stephen; Raimondi, Manuela T.; Lamartina, Claudio; Brayda-Bruno, Marco; Fornari, Maurizio

    2008-01-01

    The implantation of lumbar disc prostheses based on different design concepts is widely accepted. This paper reviews currently available literature studies on the biomechanics of TDA in the lumbar spine, and is targeted at the evaluation of possible relationships between the aims of TDA and the geometrical, mechanical and material properties of the various available disc prostheses. Both theoretical and experimental studies were analyzed, by a PUBMED search (performed in February 2007, revised in January 2008), focusing on single level TDA. Both semi-constrained and unconstrained lumbar discs seem to be able to restore nearly physiological IAR locations and ROM values. However, both increased and decreased ROM was stated in some papers, unrelated to the clinical outcome. Segmental lordosis alterations after TDA were reported in most cases, for both constrained and unconstrained disc prostheses. An increase in the load through the facet joints was documented, for both semi-constrained and unconstrained artificial discs, but with some contrasting results. Semi-constrained devices may be able to share a greater part of the load, thus protecting the surrounding biological structure from overloading and possible early degeneration, but may be more susceptible to wear. The next level of development will be the biomechanical integration of compression across the motion segment. All these findings need to be supported by long-term clinical outcome studies. PMID:18946684

  5. Fusion versus Bryan Cervical Disc in two-level cervical disc disease: a prospective, randomised study

    PubMed Central

    Nie, Lin; Zhang, Li; Hou, Yong

    2008-01-01

    In this prospective study, our aim was to compare the functional results and radiographic outcomes of fusion and Bryan Cervical Disc replacement in the treatment of two-level cervical disc disease. A total of 65 patients with two-level cervical disc disease were randomly assigned to two groups, those operated on with Bryan Cervical Disc replacement (31) and those operated on with anterior cervical fusion with an iliac crest autograft and plate (34). Clinical evaluation was carried out using the visual analogue scale (VAS), the Short Form 36 (SF-36) and the neck disability index (NDI) during a two year follow-up. Radiological evaluation sought evidence of range of motion, stability and subsidence of the prosthesis. Substantial reduction in NDI scores occurred in both groups, with greater percent improvement in the Bryan group (P = 0.023). The arm pain VAS score improvement was substantial in both groups. Bryan artificial cervical disc replacement seems reliable and safe in the treatment of patients with two-level cervical disc disease. PMID:18956190

  6. A nanoflare model for active region radiance: application of artificial neural networks

    NASA Astrophysics Data System (ADS)

    Bazarghan, M.; Safari, H.; Innes, D. E.; Karami, E.; Solanki, S. K.

    2008-12-01

    Context: Nanoflares are small impulsive bursts of energy that blend with and possibly make up much of the solar background emission. Determining their frequency and energy input is central to understanding the heating of the solar corona. One method is to extrapolate the energy frequency distribution of larger individually observed flares to lower energies. Only if the power law exponent is greater than 2 is it considered possible that nanoflares contribute significantly to the energy input. Aims: Time sequences of ultraviolet line radiances observed in the corona of an active region are modelled with the aim of determining the power law exponent of the nanoflare energy distribution. Methods: A simple nanoflare model based on three key parameters (the flare rate, the flare duration, and the power law exponent of the flare energy frequency distribution) is used to simulate emission line radiances from the ions Fe XIX, Ca XIII, and Si III, observed by SUMER in the corona of an active region as it rotates around the east limb of the Sun. Light curve pattern recognition by an Artificial Neural Network (ANN) scheme is used to determine the values. Results: The power law exponents, α≈2.8, 2.8, and 2.6 are obtained for Fe XIX, Ca XIII, and Si III respectively. Conclusions: The light curve simulations imply a power law exponent greater than the critical value of 2 for all ion species. This implies that if the energy of flare-like events is extrapolated to low energies, nanoflares could provide a significant contribution to the heating of active region coronae.

  7. Seasonal prediction of tropical cyclone activity over the north Indian Ocean using three artificial neural networks

    NASA Astrophysics Data System (ADS)

    Nath, Sankar; Kotal, S. D.; Kundu, P. K.

    2016-03-01

    Three artificial neural network (ANN) methods, namely, multilayer perceptron (MLP), radial basis function (RBF) and generalized regression neural network (GRNN) are utilized to predict the seasonal tropical cyclone (TC) activity over the north Indian Ocean (NIO) during the post-monsoon season (October, November, December). The frequency of TC and large-scale climate variables derived from NCEP/NCAR reanalysis dataset of resolution 2.5° × 2.5° were analyzed for the period 1971-2013. Data for the years 1971-2002 were used for the development of the models, which were tested with independent sample data for the year 2003-2013. Using the correlation analysis, the five large-scale climate variables, namely, geopotential height at 500 hPa, relative humidity at 500 hPa, sea-level pressure, zonal wind at 700 hPa and 200 hPa for the preceding month September, are selected as potential predictors of the post-monsoon season TC activity. The result reveals that all the three different ANN methods are able to provide satisfactory forecast in terms of the various metrics, such as root mean-square error (RMSE), standard deviation (SD), correlation coefficient (r), and bias and index of agreement (d). Additionally, leave-one-out cross validation (LOOCV) method is also performed and the forecast skill is evaluated. The results show that the MLP model is found to be superior to the other two models (RBF, GRNN). The (MLP) is expected to be very useful to operational forecasters for prediction of TC activity.

  8. Determination of DPPH free radical scavenging activity: application of artificial neural networks.

    PubMed

    Musa, Khalid Hamid; Abdullah, Aminah; Al-Haiqi, Ahmed

    2016-03-01

    A new computational approach for the determination of 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity (DPPH-RSA) in food is reported, based on the concept of machine learning. Trolox standard was mix with DPPH at different concentrations to produce different colors from purple to yellow. Artificial neural network (ANN) was trained on a typical set of images of the DPPH radical reacting with different levels of Trolox. This allowed the neural network to classify future images of any sample into the correct class of RSA level. The ANN was then able to determine the DPPH-RSA of cinnamon, clove, mung bean, red bean, red rice, brown rice, black rice and tea extract and the results were compared with data obtained using a spectrophotometer. The application of ANN correlated well to the spectrophotometric classical procedure and thus do not require the use of spectrophotometer, and it could be used to obtain semi-quantitative results of DPPH-RSA. PMID:26471610

  9. DETECTING ACTIVE GALACTIC NUCLEI USING MULTI-FILTER IMAGING DATA. II. INCORPORATING ARTIFICIAL NEURAL NETWORKS

    SciTech Connect

    Dong, X. Y.; De Robertis, M. M.

    2013-10-01

    This is the second paper of the series Detecting Active Galactic Nuclei Using Multi-filter Imaging Data. In this paper we review shapelets, an image manipulation algorithm, which we employ to adjust the point-spread function (PSF) of galaxy images. This technique is used to ensure the image in each filter has the same and sharpest PSF, which is the preferred condition for detecting AGNs using multi-filter imaging data as we demonstrated in Paper I of this series. We apply shapelets on Canada-France-Hawaii Telescope Legacy Survey Wide Survey ugriz images. Photometric parameters such as effective radii, integrated fluxes within certain radii, and color gradients are measured on the shapelets-reconstructed images. These parameters are used by artificial neural networks (ANNs) which yield: photometric redshift with an rms of 0.026 and a regression R-value of 0.92; galaxy morphological types with an uncertainty less than 2 T types for z ≤ 0.1; and identification of galaxies as AGNs with 70% confidence, star-forming/starburst (SF/SB) galaxies with 90% confidence, and passive galaxies with 70% confidence for z ≤ 0.1. The incorporation of ANNs provides a more reliable technique for identifying AGN or SF/SB candidates, which could be very useful for large-scale multi-filter optical surveys that also include a modest set of spectroscopic data sufficient to train neural networks.

  10. Seismic activity and water level fluctuations in the artificial lakes of Aliakmonas river (NW Greece)

    NASA Astrophysics Data System (ADS)

    Petrou, Panagiota; Chouliaras, Gerasimos; Drakatos, George

    2015-04-01

    The Public Power Corporation (PPC) of Greece has established four dammed reservoirs, downstream of each other on Aliakmonas River in North Western Greece (namely the artificial lakes of Ilarionas, Polyphyto, Sfikia and Asomata). In addition to the monitoring of the reservoir water levels the PPC has also installed a dense seismological network in the wider area. In this investigation the correlation between the local seismic activity and the water level fluctuations at the Ilarionas and Polyphyto reservoirs is studied. On October 25th, 1984, during the Asomata reservoir initial filling, a Ms=5.4 earthquake occurred in the region which was characterized by weak seismicity, until the strong earthquake of Ms=6.5 that occurred on May 13th, 1995, at a distance of 18 km from the southern edge of the Polyphyto reservoir. More recently, on July 2nd and 3rd, 2013, two moderate earthquakes (Ml=4.7 and Ml=4.6) occurred, almost a year after the filling of the Ilarionas reservoir in 2012. In addition to these events, fourteen earthquakes with magnitudes equal or greater to Ml=4 have also been detected in the wider area of the Aliakmonas reservoir.

  11. Seeing by Touch: Evaluation of a Soft Biologically-Inspired Artificial Fingertip in Real-Time Active Touch

    PubMed Central

    Assaf, Tareq; Roke, Calum; Rossiter, Jonathan; Pipe, Tony; Melhuish, Chris

    2014-01-01

    Effective tactile sensing for artificial platforms remains an open issue in robotics. This study investigates the performance of a soft biologically-inspired artificial fingertip in active exploration tasks. The fingertip sensor replicates the mechanisms within human skin and offers a robust solution that can be used both for tactile sensing and gripping/manipulating objects. The softness of the optical sensor's contact surface also allows safer interactions with objects. High-level tactile features such as edges are extrapolated from the sensor's output and the information is used to generate a tactile image. The work presented in this paper aims to investigate and evaluate this artificial fingertip for 2D shape reconstruction. The sensor was mounted on a robot arm to allow autonomous exploration of different objects. The sensor and a number of human participants were then tested for their abilities to track the raised perimeters of different planar objects and compared. By observing the technique and accuracy of the human subjects, simple but effective parameters were determined in order to evaluate the artificial system's performance. The results prove the capability of the sensor in such active exploration tasks, with a comparable performance to the human subjects despite it using tactile data alone whereas the human participants were also able to use proprioceptive cues. PMID:24514881

  12. Bio-inspired electron-delivering system for reductive activation of dioxygen at metal centres towards artificial flavoenzymes.

    PubMed

    Roux, Yoann; Ricoux, Rémy; Avenier, Frédéric; Mahy, Jean-Pierre

    2015-01-01

    Development of artificial systems, capable of delivering electrons to metal-based catalysts for the reductive activation of dioxygen, has been proven very difficult for decades, constituting a major scientific lock for the elaboration of environmentally friendly oxidation processes. Here we demonstrate that the incorporation of a flavin mononucleotide (FMN) in a water-soluble polymer, bearing a locally hydrophobic microenvironment, allows the efficient reduction of the FMN by NADH. This supramolecular entity is then capable of catalysing a very fast single-electron reduction of manganese(III) porphyrin by splitting the electron pair issued from NADH. This is fully reminiscent of the activity of natural reductases such as the cytochrome P450 reductases with kinetic parameters, which are three orders of magnitude faster compared with other artificial systems. Finally, we show as a proof of concept that the reduced manganese porphyrin activates dioxygen and catalyses the oxidation of organic substrates in water. PMID:26419885

  13. Establishing wild-type levels of catalytic activity on natural and artificial (βα)8-barrel protein scaffolds

    PubMed Central

    Claren, Jörg; Malisi, Christoph; Höcker, Birte; Sterner, Reinhard

    2009-01-01

    The generation of high levels of new catalytic activities on natural and artificial protein scaffolds is a major goal of enzyme engineering. Here, we used random mutagenesis and selection in vivo to establish a sugar isomerisation reaction on both a natural (βα)8-barrel enzyme and a catalytically inert chimeric (βα)8-barrel scaffold, which was generated by the recombination of 2 (βα)4-half barrels. The best evolved variants show turnover numbers and substrate affinities that are similar to those of wild-type enzymes catalyzing the same reaction. The determination of the crystal structure of the most proficient variant allowed us to model the substrate sugar in the novel active site and to elucidate the mechanistic basis of the newly established activity. The results demonstrate that natural and inert artificial protein scaffolds can be converted into highly proficient enzymes in the laboratory, and provide insights into the mechanisms of enzyme evolution. PMID:19237570

  14. Bio-inspired electron-delivering system for reductive activation of dioxygen at metal centres towards artificial flavoenzymes

    PubMed Central

    Roux, Yoann; Ricoux, Rémy; Avenier, Frédéric; Mahy, Jean-Pierre

    2015-01-01

    Development of artificial systems, capable of delivering electrons to metal-based catalysts for the reductive activation of dioxygen, has been proven very difficult for decades, constituting a major scientific lock for the elaboration of environmentally friendly oxidation processes. Here we demonstrate that the incorporation of a flavin mononucleotide (FMN) in a water-soluble polymer, bearing a locally hydrophobic microenvironment, allows the efficient reduction of the FMN by NADH. This supramolecular entity is then capable of catalysing a very fast single-electron reduction of manganese(III) porphyrin by splitting the electron pair issued from NADH. This is fully reminiscent of the activity of natural reductases such as the cytochrome P450 reductases with kinetic parameters, which are three orders of magnitude faster compared with other artificial systems. Finally, we show as a proof of concept that the reduced manganese porphyrin activates dioxygen and catalyses the oxidation of organic substrates in water. PMID:26419885

  15. Investigation of cryogenic rupture disc design

    NASA Technical Reports Server (NTRS)

    Keough, J. B.; Oldland, A. H.

    1973-01-01

    Rupture disc designs of both the active (command actuated) and passive (pressure ruptured) types were evaluated for performance characteristics at cryogenic temperatures and for capability to operate in a variety of cryogens, including gaseous and liquid fluorine. The test results, coupled with information from literature and industry searches, were used to establish a statement of design criteria and recommended practices for application of rupture discs to cryogenic rocket propellant feed and vent systems.

  16. Precision diagnostic disc injections.

    PubMed

    Fortin, J D

    2000-07-01

    Spinal pain is an important public health problem affecting the population indiscriminately. The structures responsible for pain in the spine include the vertebrae, intervertebral discs, spinal cord, nerve roots, facet joints, ligaments, muscles, atlanto-occipital joints, atlanto-axial joints, and sacroiliac joints. Even though disc herniation, facet joints, strained muscles, and torn ligaments have been attributed to be the cause of most spinal pain, either in the neck and upper extremities, upper and mid back, or low back and lower extremities, disorders of the disc other than disc herniation have been implicated more frequently than any other disorders. Once stifled by misinformation, discography now has applications in a number of clinical settings. While cervical and lumbar discography is well studied and well known, thoracic discography is in its nascent stages of clinical application. The value of discography lies in its ability to produce pain and thereby identify a "pain generator." This allows treatment to be based on the specific cause of pain. The three primary components of diagnostic disc injection are: provocation/analgesia, discometry, and nucleography. Despite the recent exponential growth of noninvasive spinal technology, diagnostic disc injection remains the sole direct method for definitively determining whether a disc is a physiological pain generator. It is clear that discography is a safe and powerful complement to the overall clinical context. PMID:16906185

  17. Percutaneous laser disc decompression.

    PubMed

    Choy, D S

    1995-06-01

    Herniated disc disease has an incidence of 1.7% in the U.S. Heretofore, open operative procedures were the rule for this condition when conservative measures were ineffective. Choy and Ascher introduced this new technique in February 1986 using a Nd:YAG laser introduced into the disc through an optical fiber in a needle. Percutaneous laser disc decompression is based on the principle that in an enclosed hydraulic space, such as an intact disc, a small reduction in volume is associated with a disproportionate fall in pressure. In the disc, this partial vacuum causes the herniated portion to move away from the nerve root back toward the center of the disc. This technique has been taught worldwide and is being performed in most of Europe, Japan, the United States, and Korea. In this special issue devoted to percutaneous laser disc decompression (PLDD), we will set forth the basic science of PLDD, patient selection, use of the holmium:YAG, and the Nd:YAG lasers, operative technique, and results. PMID:10150634

  18. A Biohybrid Artificial Lung Prototype With Active Mixing of Endothelialized Microporous Hollow Fibers

    PubMed Central

    Polk, Alexa A.; Maul, Timothy M.; McKeel, Daniel T.; Snyder, Trevor A.; Lehocky, Craig A.; Pitt, Bruce; Stolz, Donna Beer; Federspiel, William J.; Wagner, William R.

    2014-01-01

    Acute respiratory distress syndrome (ARDS) affects nearly 150,000 patients per year in the US, and is associated with high mortality (≈40%) and suboptimal options for patient care. Mechanical ventilation and extracorporeal membrane oxygenation are limited to short-term use due to ventilator-induced lung injury and poor bio-compatibility, respectively. In this report, we describe the development of a biohybrid lung prototype, employing a rotating endothelialized microporous hollow fiber (MHF) bundle to improve blood biocompatibility while MHF mixing could contribute to gas transfer efficiency. MHFs were surface modified with radio frequency glow discharge (RFGD) and protein adsorption to promote endothelial cell (EC) attachment and growth. The MHF bundles were placed in the biohybrid lung prototype and rotated up to 1,500 revolutions per minute (rpm) using speed ramping protocols to condition ECs to remain adherent on the fibers. Oxygen transfer, thrombotic deposition, and EC p-selectin expression were evaluated as indicators of biohybrid lung functionality and biocompatibility. A fixed aliquot of blood in contact with MHF bundles rotated at either 250 or 750 rpm reached saturating pO2 levels more quickly with increased rpm, supporting the concept that fiber rotation would positively contribute to oxygen transfer. The presence of ECs had no effect on the rate of oxygen transfer at lower fiber rpm, but did provide some resistance with increased rpm when the overall rate of mass transfer was higher due to active mixing. RFGD followed by fibronectin adsorption on MHFs facilitated near confluent EC coverage with minimal p-selectin expression under both normoxic and hyperoxic conditions. Indeed, even subconfluent EC coverage on MHFs significantly reduced thrombotic deposition adding further support that endothelialization enhances, blood biocompatibility. Overall these findings demonstrate a proof-of-concept that a rotating endothelialized MHF bundle enhances gas

  19. Reconstructing the star formation history of the Milky Way disc(s) from chemical abundances

    NASA Astrophysics Data System (ADS)

    Snaith, O.; Haywood, M.; Di Matteo, P.; Lehnert, M. D.; Combes, F.; Katz, D.; Gómez, A.

    2015-06-01

    We develop a chemical evolution model to study the star formation history of the Milky Way. Our model assumes that the Milky Way has formed from a closed-box-like system in the inner regions, while the outer parts of the disc have experienced some accretion. Unlike the usual procedure, we do not fix the star formation prescription (e.g. Kennicutt law) to reproduce the chemical abundance trends. Instead, we fit the abundance trends with age to recover the star formation history of the Galaxy. Our method enables us to recover the star formation history of the Milky Way in the first Gyrs with unprecedented accuracy in the inner (R < 7-8 kpc) and outer (R > 9-10 kpc) discs, as sampled in the solar vicinity. We show that half the stellar mass formed during the thick-disc phase in the inner galaxy during the first 4-5 Gyr. This phase was followed by a significant dip in star formation activity (at 8-9 Gyr) and a period of roughly constant lower-level star formation for the remaining 8 Gyr. The thick-disc phase has produced as many metals in 4 Gyr as the thin-disc phase in the remaining 8 Gyr. Our results suggest that a closed-box model is able to fit all the available constraints in the inner disc. A closed-box system is qualitatively equivalent to a regime where the accretion rate maintains a high gas fraction in the inner disc at high redshift. In these conditions the SFR is mainly governed by the high turbulence of the interstellar medium. By z ~ 1 it is possible that most of the accretion takes place in the outer disc, while the star formation activity in the inner disc is mostly sustained by the gas that is not consumed during the thick-disc phase and the continuous ejecta from earlier generations of stars. The outer disc follows a star formation history very similar to that of the inner disc, although initiated at z ~ 2, about 2 Gyr before the onset of the thin-disc formation in the inner disc.

  20. Disc replacement using Pro-Disc C versus fusion: a prospective randomised and controlled radiographic and clinical study

    PubMed Central

    Ahlhelm, F.; Pitzen, T.; Steudel, W. I.; Jung, J.; Shariat, K.; Steimer, O.; Bachelier, F.; Pape, D.

    2006-01-01

    Anterior cervical discectomy and fusion (ACDF) may be considered to be the gold standard for treatment of symptomatic degenerative disc disease within the cervical spine. However, fusion of the segment may result in progressive degeneration of the adjacent segments. Therefore, dynamic stabilization procedures have been introduced. Among these, artificial disc replacement by disc prosthesis seems to be promising. However, to be so, segmental motion must be preserved. This, again, is very difficult to judge and has not yet been proven. The aim of the current study was to first analyse the segmental motion following artificial disc replacement using a disc prosthesis. A second aim was to compare both segmental motion as well as clinical result to the current gold standard (ACDF). This is a prospective controlled study. Twenty-five patients with cervical disc herniation were enrolled and assigned to either study group (receiving a disc prosthesis) or control group (receiving ACDF, using a cage with bone graft and an anterior plate.) Radiostereometric analysis was used to quantify intervertebral motion immediately as well as 3, 6, 12 and 24 weeks postoperatively. Further, clinical results were judged using visual analogue scale and neuro-examination. Cervical spine segmental motion decreased over time in the presence of disc prosthesis or ACDF. However, the loss of segmental motion is significantly higher in the ACDF group, when looked at 3, 6, 12 and 24 weeks after surgery. We observed significant pain reduction in neck and arm postoperatively, without significant difference between both groups (P > 0.05). Cervical spine disc prosthesis preserves cervical spine segmental motion within the first 6 months after surgery. The clinical results are the same when compared to the early results following ACDF. PMID:17106665

  1. Proteomic Signature of the Murine Intervertebral Disc

    PubMed Central

    McCann, Matthew R.; Patel, Priya; Frimpong, Agya; Xiao, Yizhi; Siqueira, Walter L.; Séguin, Cheryle A.

    2015-01-01

    Low back pain is the most common musculoskeletal problem and the single most common cause of disability, often attributed to degeneration of the intervertebral disc. Lack of effective treatment is directly related to our limited understanding of the pathways responsible for maintaining disc health. While transcriptional analysis has permitted initial insights into the biology of the intervertebral disc, complete proteomic characterization is required. We therefore employed liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) protein/peptide separation and mass spectrometric analyses to characterize the protein content of intervertebral discs from skeletally mature wild-type mice. A total of 1360 proteins were identified and categorized using PANTHER. Identified proteins were primarily intracellular/plasma membrane (35%), organelle (30%), macromolecular complex (10%), extracellular region (9%). Molecular function categorization resulted in three distinct categories: catalytic activity (33%), binding (molecule interactions) (29%), and structural activity (13%). To validate our list, we confirmed the presence of 14 of 20 previously identified IVD-associated markers, including matrix proteins, transcriptional regulators, and secreted proteins. Immunohistochemical analysis confirmed distinct localization patterns of select protein with the intervertebral disc. Characterization of the protein composition of healthy intervertebral disc tissue is an important first step in identifying cellular processes and pathways disrupted during aging or disease progression. PMID:25689066

  2. Morphology controlled bulk synthesis of disc-shaped WO3 powder and evaluation of its photocatalytic activity for the degradation of phenols.

    PubMed

    Aslam, M; Ismail, Iqbal M I; Chandrasekaran, S; Hameed, A

    2014-07-15

    The surfactant assisted synthesis of disc-shaped WO3 powder and its photocatalytic performance in sunlight exposure is reported. UV-vis DRS, XRD and FESEM characterized the synthesized WO3. The synthesized powder exhibited a bandgap of ∼2.55eV with cubic lattice and high crystallinity. The photocatalytic activity of the synthesized WO3 was examined for the degradation of phenol, resorcinol, 2-chlorophenol and 2-nitrophenol in complete spectrum and visible segment of sunlight. The highly efficient degradation/mineralization of 2-chloro and 2-nitrophenol compared to that of phenol and resorcinol, under identical experimental conditions, suggested the regulatory role of substituents attached to the aromatic ring in degradation/mineralization process. The time-scale HPLC degradation profiles, identification of intermediates by GC-MS and removal of organic carbon during the course of reaction were utilized to approximate the possible route of degradation/mineralization of phenolic substrates. The measurement of the anions released during the photocatalytic process was used to identify the nature of the major oxidants (O2(•-), OH(•)) and the possible interaction sites. A significant decrease in the photocatalytic activity of synthesized WO3, ∼50%, was observed in visible portion of sunlight however, a sustained activity was observed in the repeated exposures. PMID:24869630

  3. Herniated Lumbar Disc

    MedlinePlus

    ... 50. A herniated lumbar disc may also cause back pain, although back pain alone (without leg pain) can have many causes ... 90% success); surgery is less effective in relieving back pain. Nonsurgical treatment Your doctor may prescribe nonsurgical treatments ...

  4. Sweet taste receptor expression in ruminant intestine and its activation by artificial sweeteners to regulate glucose absorption.

    PubMed

    Moran, A W; Al-Rammahi, M; Zhang, C; Bravo, D; Calsamiglia, S; Shirazi-Beechey, S P

    2014-01-01

    Absorption of glucose from the lumen of the intestine into enterocytes is accomplished by sodium-glucose co-transporter 1 (SGLT1). In the majority of mammalian species, expression (this includes activity) of SGLT1 is upregulated in response to increased dietary monosaccharides. This regulatory pathway is initiated by sensing of luminal sugar by the gut-expressed sweet taste receptor. The objectives of our studies were to determine (1) if the ruminant intestine expresses the sweet taste receptor, which consists of two subunits [taste 1 receptor 2 (T1R2) and 3 (T1R3)], and other key signaling molecules required for SGLT1 upregulation in nonruminant intestines, and (2) whether T1R2-T1R3 sensing of artificial sweeteners induces release of glucagon-like peptide-2 (GLP-2) and enhances SGLT1 expression. We found that the small intestine of sheep and cattle express T1R2, T1R3, G-protein gustducin, and GLP-2 in enteroendocrine L-cells. Maintaining 110-d-old ruminating calves for 60d on a diet containing a starter concentrate and the artificial sweetener Sucram (consisting of saccharin and neohesperidin dihydrochalcone; Pancosma SA, Geneva, Switzerland) enhances (1) Na(+)-dependent d-glucose uptake by over 3-fold, (2) villus height and crypt depth by 1.4- and 1.2-fold, and (3) maltase- and alkaline phosphatase-specific activity by 1.5-fold compared to calves maintained on the same diet without Sucram. No statistically significant differences were observed for rates of intestinal glucose uptake, villus height, crypt depth, or enzyme activities between 50-d-old milk-fed calves and calves maintained on the same diet containing Sucram. When adult cows were kept on a diet containing 80:20 ryegrass hay-to-concentrate supplemented with Sucram, more than a 7-fold increase in SGLT1 protein abundance was noted. Collectively, the data indicate that inclusion of this artificial sweetener enhances SGLT1 expression and mucosal growth in ruminant animals. Exposure of ruminant sheep

  5. Can manipulating water color deter piscivorous bird activity within an artificial environment?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent advancements in studies within the fields of avian acuity and remote sensing have allowed ecologists a unique opportunity to conduct field experiments within the birds' perceived environment. This study was an attempt to test and predict piscivorous bird use and avoidance within an artificial...

  6. Development of Dual-Activity Vectors by Co-Envelopment of Adenovirus and SiRNA in Artificial Lipid Bilayers

    PubMed Central

    Yilmazer, Açelya; Tian, Bowen; Kostarelos, Kostas

    2014-01-01

    Gene therapy with human adenovirus type 5 (Ad5) has been extensively explored for the treatment of diseases resistant to traditional therapies. Intravenous administration leads to rapid clearance from blood circulation and high liver accumulation, which restrict the use of Ad-based vectors in clinical gene therapy protocols that involve systemic administration. We have previously proposed that such limitations can be improved by engineering artificial lipid envelopes around Ad and designed a variety of artificial lipid bilayer envelopes around the viral capsid. In this study, we sought to explore further opportunities that the artificially enveloped virus constructs could offer, by designing a previously unreported gene therapy vector by simultaneous envelopment of Ad and siRNA within the same lipid bilayer. Such a dual-activity vector can offer efficacious therapy for different genetic disorders where both turning on and switching off genes would be needed. Dynamic light scattering, transmission electron microscopy and atomic force microscopy were used to characterize these vectors. Agarose gel electrophoresis, Ribo green and dot blot assays showed that siRNA and Ad virions can be enveloped together within lipid bilayers at high envelopment efficiency. Cellular uptake and in vitro transfection experiments were carried out to show the feasibility of combining siRNA-mediated gene silencing with viral gene transfer using these newly designed dual-activity vectors. PMID:25501573

  7. Construction of GPx active centers on natural protein nanodisk/nanotube: a new way to develop artificial nanoenzyme.

    PubMed

    Hou, Chunxi; Luo, Quan; Liu, Jinliang; Miao, Lu; Zhang, Chunqiu; Gao, Yuzhou; Zhang, Xiyu; Xu, Jiayun; Dong, Zeyuan; Liu, Junqiu

    2012-10-23

    Construction of catalytic centers on natural protein aggregates is a challenging topic in biomaterial and biomedicine research. Here we report a novel construction of artificial nanoenzyme with glutathione peroxidase (GPx)-like function. By engineering the surface of tobacco mosaic virus (TMV) coat protein, the main catalytic components of GPx were fabricated on TMV protein monomers. Through direct self-assembly of the functionalized viral coat proteins, the multi-GPx centers were installed on these well-defined nanodisks or nanotubes. With the help of muti-selenoenzyme centers, the resulting organized nanoenzyme exhibited remarkable GPx activity, even approaching the level of natural GPx. The antioxidation study on subcell mitochondrial level demonstrated that virus-based nanoenzyme exerted excellent capacity for protecting cell from oxidative damage. This strategy represents a new way to develop artificial nanoenzymes. PMID:22992167

  8. Two-level total lumbar disc replacement

    PubMed Central

    Bakaloudis, Georgios; Lolli, Francesco; Vommaro, Francesco; Parisini, Patrizio

    2009-01-01

    Total lumbar disc replacement (TDR) has been widely used as a treatment option for 2-level symptomatic degenerative disc disease. However, recent studies have presented conflicting results and some authors concluded that outcome deteriorated when disc replacement was performed bisegmentally, with an increase of complications for bisegmental replacements in comparison with monosegmental disc arthroplasty. The goal of the present retrospective study is to investigate results in a group of patients who have received bisegmental TDR with SB Charitè III artificial disc for degenerative disc disease with a minimum follow-up of 3 years, and to compare the results of 2-level disc replacement versus 1-level patients treated with the same prosthesis. A total of 32 patients had at least 3-years follow-up and were reviewed. The average age of the patients was 38.5 years. There were 11 males and 21 females. About 16 patients received 2-level TDR (SB Charitè III) and 16 received 1-level TDR (SB Charitè III). Both radiographic and functional outcome analysis, including patient’s satisfaction, was performed. There were no signs of degenerative changes of the adjacent segments in any case of the 2- or 1-level TDR. There was no statistically significant difference between 2- and 1-level TDR both at 12 months and at 3-years follow-up on functional outcome scores. There was a statistically insignificant difference concerning the patients satisfaction between 1- and 2-level surgeries at the last follow-up (P = 0.46). In the 2-level TDR patients, there were 5 minor complications (31.25%), whereas major complications occurred in 4 more patients (25%) and required a new surgery in 2 cases (12.5%). In the 1-level cases there were 2 minor complications (12.5%) and 2 major complications (12.5%) and a new revision surgery was required in 1 patient (6.25%). In conclusion, the use of 2-level disc replacement at last follow-up presented a higher incidence of complications than in cases

  9. 50 years of scientific activities the station Lviv --1031 for observation of artificial satellites

    NASA Astrophysics Data System (ADS)

    Natalie, Virun

    The station Lviv-1031 for optical observations of artificial satellites was founded in summer 1957 by Astronomical Council (Astrosovet) of Academy of Sciences USSR based on Ivan Franko State university (at present national university). In the beginning the visual observations the successful observations of the first artificial satellite took place in Lviv, afterwards the next artificial satellites apply conditions for the development of hardware, software, expansion of observational methods, creation of special scientific staff. Photographic, later photometric and laser ranging observations came to take visual observation's place. However, Lviv station exists to present days as a department of Astronomical observatory National University of Lviv. Laser ranging observations are made with 1m-telescope TPL-1M, photometric observations - the 2x35cm photo-polarimeter and positional observations 2x10cm and CCD camera. The laser ranging part of the department has the name Lviv-1831 and belongs to the network ILRS (The International Laser Ranging Service). The present equipment of station allows ranging of satellites not lower than 900 km with a single shot precision about 50mm.

  10. Enhancing the Activity of Peptide-Based Artificial Hydrolase with Catalytic Ser/His/Asp Triad and Molecular Imprinting.

    PubMed

    Wang, Mengfan; Lv, Yuqi; Liu, Xiaojing; Qi, Wei; Su, Rongxin; He, Zhimin

    2016-06-01

    In this study, an artificial hydrolase was developed by combining the catalytic Ser/His/Asp triad with N-fluorenylmethoxycarbonyl diphenylalanine (Fmoc-FF), followed by coassembly of the peptides into nanofibers (CoA-HSD). The peptide-based nanofibers provide an ideal supramolecular framework to support the functional groups. Compared with the self-assembled catalytic nanofibers (SA-H), which contain only the catalytic histidine residue, the highest activity of CoA-HSD occurs when histidine, serine, and aspartate residues are at a ratio of 40:1:1. This indicates that the well-ordered nanofiber structure and the synergistic effects of serine and aspartate residues contribute to the enhancement in activity. Additionally, for the first time, molecular imprinting was applied to further enhance the activity of the peptide-based artificial enzyme (CoA-HSD). p-NPA was used as the molecular template to arrange the catalytic Ser/His/Asp triad residues in the proper orientation. As a result, the activity of imprinted coassembled CoA-HSD nanofibers is 7.86 times greater than that of nonimprinted CoA-HSD and 13.48 times that of SA-H. PMID:27191381

  11. Crystallization of Self-Propelled Hard Discs.

    PubMed

    Briand, G; Dauchot, O

    2016-08-26

    We experimentally study the crystallization of a monolayer of vibrated discs with a built-in polar asymmetry, a model system of active liquids, and contrast it with that of vibrated isotropic discs. Increasing the packing fraction ϕ, the quasicontinuous crystallization reported for isotropic discs is replaced by a transition, or a crossover, towards a "self-melting" crystal. Starting from the liquid phase and increasing the packing fraction, clusters of dense hexagonal-ordered packed discs spontaneously form, melt, split, and merge, leading to a highly intermittent and heterogeneous dynamics. For a packing fraction larger than ϕ^{*}, a few large clusters span the system size. The cluster size distribution is monotonically decreasing for ϕ<ϕ^{*}, nonmonotonic for ϕ>ϕ^{*}, and is a power law at the transition. The system is, however, never dynamically arrested. The clusters permanently melt from place to place, forming droplets of an active liquid which rapidly propagate across the system. This self-melting crystalline state subsists up to the highest possible packing fraction, questioning the stability of the crystal for active discs unless it is at ordered close packing. PMID:27610889

  12. Artificial Intelligence.

    ERIC Educational Resources Information Center

    Waltz, David L.

    1982-01-01

    Describes kinds of results achieved by computer programs in artificial intelligence. Topics discussed include heuristic searches, artificial intelligence/psychology, planning program, backward chaining, learning (focusing on Winograd's blocks to explore learning strategies), concept learning, constraint propagation, language understanding…

  13. Comparisons and connections between mean field dynamo theory and accretion disc theory

    NASA Astrophysics Data System (ADS)

    Blackman, E. G.

    2010-01-01

    The origin of large scale magnetic fields in astrophysical rotators, and the conversion of gravitational energy into radiation near stars and compact objects via accretion have been subjects of active research for a half century. Magnetohydrodynamic turbulence makes both problems highly nonlinear, so both subjects have benefitted from numerical simulations.However, understanding the key principles and practical modeling of observations warrants testable semi-analytic mean field theories that distill the essential physics. Mean field dynamo (MFD) theory and alpha-viscosity accretion disc theory exemplify this pursuit. That the latter is a mean field theory is not always made explicit but the combination of turbulence and global symmetry imply such. The more commonly explicit presentation of assumptions in 20th century textbook MFDT has exposed it to arguably more widespread criticism than incurred by 20th century alpha-accretion theory despite complementary weaknesses. In the 21st century however, MFDT has experienced a breakthrough with a dynamical saturation theory that consistently agrees with simulations. Such has not yet occurred in accretion disc theory, though progress is emerging. Ironically however, for accretion engines, MFDT and accretion theory are presently two artificially uncoupled pieces of what should be a single coupled theory. Large scale fields and accretion flows are dynamically intertwined because large scale fields likely play a key role in angular momentum transport. I discuss and synthesize aspects of recent progress in MFDT and accretion disc theory to suggest why the two likely conspire in a unified theory.

  14. The Reading Disc: Learning to Read Using Interactive CD.

    ERIC Educational Resources Information Center

    Shaw, Simon

    1991-01-01

    Describes the development of an interactive compact disc on CD-ROM XA that was designed to help adults learn to read. The application of technology to learning is discussed, differences in learner control in computer-based systems are considered, virtual writing is described, and assessment activities available on the disc are explained. (five…

  15. Product and process for manufacturing an optical disc master

    SciTech Connect

    Dobbin, R.B.; Loeppky, D.G.; Norton, J.R.; Del Mar, B.E.

    1994-01-11

    The invention discloses a simplified four step process for making an optical disc master or alternatively a WORM disc by first making or obtaining a transparent polymer disc with a tracking groove of desired geometry molded therein, then spin coating an optically active lamina on the grooved side of the disc, then recording data on said polymer disc with groove controlled and tracked laser means by ablating active lamina, forming pits, the shape of which is determined by the groove geometry and finally depositing a conductive and reflective lamina over the pitted active lamina. To change the OD master to an OD WORM, a protective cover is added to the electrically conductive and optically reflective lamina. 12 figs.

  16. Activation of polyphosphoinositide metabolism at artificial maturation of Patella vulgata oocytes.

    PubMed

    Borg, B; De Renzis, G; Payan, P; Ciapa, B

    1992-01-01

    The metabolism of polyphosphoinositides (PPI) has been investigated during the meiosis reinitiation of the oocytes of a prosobranch mollusk, the limpet Patella vulgata. Meiosis reinitiation which leads to germinal vesicle breakdown (GVBD) and metaphase-1 spindle formation was artificially induced by treating the prophase-blocked oocytes with 10 mM NH4Cl, pH 8.2. This treatment, which results in a rise in intracellular pH, triggered a general increase in polyphosphoinositide synthesis. Determinations of phosphorus content showed that maturation induced a 30 to 50% increase in both phosphatidylinositol (PI) and phosphatidylinositol-1 monophosphate (PIP) concentrations. Incorporations of 32PO4 and [3H]inositol have been measured in three classes of polyphosphoinositides: PI, PIP, and phosphatidylinositol 4,5-bisphosphate (PIP2). By comparing incorporation rates of the radiolabeled precursors into PPI before and after meiosis reinitiation, we found that artificial maturation by ammonia induced a 50-fold increase in the turnover of these lipids. No significant burst of inositol 1,4,5-trisphosphate (IP3) was observed after maturation. We suggest that modifications in PPI metabolism occurring at maturation of Patella oocytes might ensure the formation of an important stock of PPI that would be available for the profuse production of IP3, the messenger responsible for the Ca2+ signal at fertilization. PMID:1309456

  17. Artificial Intelligence.

    ERIC Educational Resources Information Center

    Information Technology Quarterly, 1985

    1985-01-01

    This issue of "Information Technology Quarterly" is devoted to the theme of "Artificial Intelligence." It contains two major articles: (1) Artificial Intelligence and Law" (D. Peter O'Neill and George D. Wood); (2) "Artificial Intelligence: A Long and Winding Road" (John J. Simon, Jr.). In addition, it contains two sidebars: (1) "Calculating and…

  18. Comparison of tablets and paper discs for antibiotic sensitivity testing.

    PubMed Central

    Brown, D F; Kothari, D

    1975-01-01

    The value of tablets and paper discs as reservoirs of antimicrobial agents for use in sensitivity testing was compared. Antibiotics that were unstable in paper discs showed no demonstrable loss of activity in tablets over a period of 50 days under adverse storage conditions. The antibiotic content of commercially prepared tablets is very high in comparison with the accepted content of paper discs used in Britain, but not all of the agent is released from tablets during tests. Comparison of the size of zones of inhibition around tablets and standard paper discs indicated that the amount of the various agents released from the tablets varied between 2-6% and 69% of the stated content. In tests of the sensitivity of a range of common pathogenic organisms, the results obtained with the tablet method--when interpreted as recommended by the manufacturer--were generally similar to those obtained with a paper disc method commonly used in British laboratories. In 47% of tests with aminoglycoside antibiotics, however, strains sensitive by the disc method were 'intermediate' or resistant by the tablet method. As with paper discs, it was necessary to press the tablets on to the medium. With adjustment of the 'effective antibiotic content of tablets to bring it into line with the accepted content in paper discs, the stability of antibiotics in the tablets might make them an acceptable alternative to paper discs. PMID:1206124

  19. The Chemistry of Optical Discs.

    ERIC Educational Resources Information Center

    Birkett, David

    2002-01-01

    Explains the chemistry used in compact discs (CD), digital versatile discs (DVD), and magneto-optical (MO) discs focusing on the steps of initial creation of the mold, the molding of the polycarbonate, the deposition of the reflective layers, the lacquering of the CDs, and the bonding of DVDs. (Contains 15 references.) (YDS)

  20. How do accretion discs break?

    NASA Astrophysics Data System (ADS)

    Dogan, Suzan

    2016-07-01

    Accretion discs are common in binary systems, and they are often found to be misaligned with respect to the binary orbit. The gravitational torque from a companion induces nodal precession in misaligned disc orbits. In this study, we first calculate whether this precession is strong enough to overcome the internal disc torques communicating angular momentum. We compare the disc precession torque with the disc viscous torque to determine whether the disc should warp or break. For typical parameters precession wins: the disc breaks into distinct planes that precess effectively independently. To check our analytical findings, we perform 3D hydrodynamical numerical simulations using the PHANTOM smoothed particle hydrodynamics code, and confirm that disc breaking is widespread and enhances accretion on to the central object. For some inclinations, the disc goes through strong Kozai cycles. Disc breaking promotes markedly enhanced and variable accretion and potentially produces high-energy particles or radiation through shocks. This would have significant implications for all binary systems: e.g. accretion outbursts in X-ray binaries and fuelling supermassive black hole (SMBH) binaries. The behaviour we have discussed in this work is relevant to a variety of astrophysical systems, for example X-ray binaries, where the disc plane may be tilted by radiation warping, SMBH binaries, where accretion of misaligned gas can create effectively random inclinations and protostellar binaries, where a disc may be misaligned by a variety of effects such as binary capture/exchange, accretion after binary formation.

  1. Revival of the Jumping Disc

    ERIC Educational Resources Information Center

    Ucke, C.; Schlichting, H-J.

    2009-01-01

    Snap discs made of bimetal have many technical applications as thermostats. Jumping discs are a toy version of such snap discs. Besides giving technical information, we describe physical investigations. We show especially how, through simple measurements and calculations, you can determine the initial speed ([approximately equal to]3.5 m…

  2. Stimulation of reproductive activity in anovulatory Alpine goats exposed to bucks treated only with artificially long days.

    PubMed

    Delgadillo, J A; Vélez, L I

    2010-12-01

    Two experiments were conducted in a subtropical latitude to determine the response of Alpine male goats to a treatment with artificially long days (experiment 1), and the response of anovulatory lactating Alpine does exposed to males treated only with artificially long days (experiment 2). In experiment 1, one group of males was kept under natural photoperiod (n = 4) while another was exposed to 2.5 months of artificially long days (16 h of light/day) from 1 December (n = 4). Plasma testosterone concentrations were determined weekly. Intensity of odor of males was determined every 2 weeks. Sexual behavior of bucks was observed during 3 days about 90 days after the end of the long day treatment. A treatment-by-time interaction was detected for testosterone secretion (P < 0.001). In control males, low plasma concentrations of testosterone were observed from March to June. In contrast, in long-day treated males, high levels of testosterone were observed from March to June (P < 0.05). A treatment-by-time interaction was detected for the intensity of male odor (P < 0.01). The male odor was stronger in long-day treated bucks than in untreated ones from March to June (P < 0.05). The number of ano-genital sniffing, nudging and flehmen was greater in long-day treated males than in untreated ones when exposed to anestrous does (P < 0.05). In experiment 2, one group of males was left under natural photoperiod variations (n = 5) and the other (n = 5) was submitted to the same photoperiodic treatment described in experiment 1. On 3 May, three untreated and three long-day treated males were put in contact with anestrous Alpine does left under natural photoperiod. Fertility was higher in does exposed to light-treated males (36/45, 80%) than those in contact with untreated ones (3/45, 7%; P < 0.05). Prolificacy was similar (P > 0.05) in does exposed to treated (1.8 ± 0.1) and untreated males (1.7 ± 0.3). These results indicate that the sexual activity of Alpine male goats raised

  3. Learning Language on Disc.

    ERIC Educational Resources Information Center

    Desmarais, Norman

    1995-01-01

    Presents a comparison of two types of compact disc (CD-ROM) foreign language tutorials: (1) those made by publishers who favor an immersion approach; and (2) those made by publishers who use grammar-based approaches. Both types of CD-ROMs address various age groups, skill levels, and learning styles. (JMV)

  4. The DISC Quotient

    NASA Astrophysics Data System (ADS)

    Elliott, John R.; Baxter, Stephen

    2012-09-01

    D.I.S.C: Decipherment Impact of a Signal's Content. The authors present a numerical method to characterise the significance of the receipt of a complex and potentially decipherable signal from extraterrestrial intelligence (ETI). The purpose of the scale is to facilitate the public communication of work on any such claimed signal, as such work proceeds, and to assist in its discussion and interpretation. Building on a "position" paper rationale, this paper looks at the DISC quotient proposed and develops the algorithmic steps and comprising measures that form this post detection strategy for information dissemination, based on prior work on message detection, decipherment. As argued, we require a robust and incremental strategy, to disseminate timely, accurate and meaningful information, to the scientific community and the general public, in the event we receive an "alien" signal that displays decipherable information. This post-detection strategy is to serve as a stepwise algorithm for a logical approach to information extraction and a vehicle for sequential information dissemination, to manage societal impact. The "DISC Quotient", which is based on signal analysis processing stages, includes factors based on the signal's data quantity, structure, affinity to known human languages, and likely decipherment times. Comparisons with human and other phenomena are included as a guide to assessing likely societal impact. It is submitted that the development, refinement and implementation of DISC as an integral strategy, during the complex processes involved in post detection and decipherment, is essential if we wish to minimize disruption and optimize dissemination.

  5. The Teddy Bears' Disc.

    ERIC Educational Resources Information Center

    Laurillard, Diana

    1985-01-01

    Reports an evaluation of the Teddy Bear disc, an interactive videodisc developed at the Open University for a second-level course in metallurgy and materials technology. Findings from observation of students utilizing the videodisc are reviewed; successful design features and design problems are considered; and development costs are outlined. (MBR)

  6. Intermediate mass black holes in AGN discs - I. Production and growth

    NASA Astrophysics Data System (ADS)

    McKernan, B.; Ford, K. E. S.; Lyra, W.; Perets, H. B.

    2012-09-01

    Here we propose a mechanism for efficiently growing intermediate mass black holes (IMBH) in discs around supermassive black holes. Stellar mass objects can efficiently agglomerate when facilitated by the gas disc. Stars, compact objects and binaries can migrate, accrete and merge within discs around supermassive black holes. While dynamical heating by cusp stars excites the velocity dispersion of nuclear cluster objects (NCOs) in the disc, gas in the disc damps NCO orbits. If gas damping dominates, NCOs remain in the disc with circularized orbits and large collision cross-sections. IMBH seeds can grow extremely rapidly by collisions with disc NCOs at low relative velocities, allowing for super-Eddington growth rates. Once an IMBH seed has cleared out its feeding zone of disc NCOs, growth of IMBH seeds can become dominated by gas accretion from the active galactic nucleus (AGN) disc. However, the IMBH can migrate in the disc and expand its feeding zone, permitting a super-Eddington accretion rate to continue. Growth of IMBH seeds via NCO collisions is enhanced by a pile-up of migrators. We highlight the remarkable parallel between the growth of IMBH in AGN discs with models of giant planet growth in protoplanetary discs. If an IMBH becomes massive enough it can open a gap in the AGN disc. IMBH migration in AGN discs may stall, allowing them to survive the end of the AGN phase and remain in galactic nuclei. Our proposed mechanisms should be more efficient at growing IMBH in AGN discs than the standard model of IMBH growth in stellar clusters. Dynamical heating of disc NCOs by cusp stars is transferred to the gas in an AGN disc helping to maintain the outer disc against gravitational instability. Model predictions, observational constraints and implications are discussed in a companion paper (Paper II).

  7. Artificial phosphorylation sites modulate the activity of a voltage-gated potassium channel

    NASA Astrophysics Data System (ADS)

    Ariyaratne, Amila; Zocchi, Giovanni

    2015-03-01

    The KvAP potassium channel is representative of a family of voltage-gated ion channels where the membrane potential is sensed by a transmembrane helix containing several positively charged arginines. Previous work by Wang and Zocchi [A. Wang and G. Zocchi, PLoS ONE 6, e18598 (2011), 10.1371/journal.pone.0018598] showed how a negatively charged polyelectrolyte attached in proximity to the voltage sensing element can bias the opening probability of the channel. Here we introduce three phosphorylation sites at the same location and show that the response curve of the channel shifts by about 20 mV upon phosphorylation, while other characteristics such as the single-channel conductance are unaffected. In summary, we construct an artificial phosphorylation site which confers allosteric regulation to the channel.

  8. Host galaxy colour gradients and accretion disc obscuration in AEGIS z ~ 1 X-ray-selected active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Pierce, C. M.; Lotz, J. M.; Salim, S.; Laird, E. S.; Coil, A. L.; Bundy, K.; Willmer, C. N. A.; Rosario, D. J. V.; Primack, J. R.; Faber, S. M.

    2010-10-01

    We describe the effect of active galactic nucleus (AGN) light on host galaxy optical and UV-optical colours, as determined from X-ray-selected AGN host galaxies at z ~ 1, and compare the AGN host galaxy colours to those of a control sample matched to the AGN sample in both redshift and stellar mass. We identify as X-ray-selected AGNs 8.7+4-3 per cent of the red-sequence control galaxies, 9.8 +/- 3 per cent of the blue-cloud control galaxies and 14.7+4-3 per cent of the green-valley control galaxies. The nuclear colours of AGN hosts are generally bluer than their outer colours, while the control galaxies exhibit redder nuclei. AGNs in blue-cloud host galaxies experience less X-ray obscuration, while AGNs in red-sequence hosts have more, which is the reverse of what is expected from general considerations of the interstellar medium. Outer and integrated colours of AGN hosts generally agree with the control galaxies, regardless of X-ray obscuration, but the nuclear colours of unobscured AGNs are typically much bluer, especially for X-ray luminous objects. Visible point sources are seen in many of these, indicating that the nuclear colours have been contaminated by AGN light and that obscuration of the X-ray radiation and visible light are therefore highly correlated. Red AGN hosts are typically slightly bluer than red-sequence control galaxies, which suggests that their stellar populations are slightly younger. We compare these colour data to current models of AGN formation. The unexpected trend of less X-ray obscuration in blue-cloud galaxies and more in red-sequence galaxies is problematic for all AGN feedback models, in which gas and dust is thought to be removed as star formation shuts down. A second class of models involving radiative instabilities in hot gas is more promising for red-sequence AGNs but predicts a larger number of point sources in red-sequence AGNs than is observed. Regardless, it appears that multiple AGN models are necessary to explain the

  9. Role of Cytokines in Intervertebral Disc Degeneration: Pain and Disc-content

    PubMed Central

    Risbud, Makarand V.; Shapiro, Irving. M

    2014-01-01

    Degeneration of the intervertebral disc is the major contributor to back/neck and radicular pain. It is characterized by an elevation in levels of the inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1 α/β, IL-6 and IL-17 secreted by the disc cells themselves; these cytokines promote matrix degradation, chemokine production and changes in cell phenotype. The resulting imbalance between catabolic and anabolic responses leads to degeneration, as well as herniation and radicular pain. Release of chemokines from degenerating discs promote infiltration and activation of T and B cells, macrophages, neutrophils, and mast cells further amplifying the inflammatory cascade. Immunocyte migration into the disc is accompanied by the appearance of microvasculature and nerve fibers arising from the dorsal root ganglion (DRG). In this inflammatory milieu, neurogenic factors in particular nerve growth factor (NGF) and brain-derive neurotrophic factor (BDNF) generated by disc and immune cells induce expression of pain associated cation channels in DRGs. Depolarization of these channels is likely to promote discogenic and radicular pain and reinforce the cytokine-mediated degenerative cascade. Taken together, the enhanced understanding of the contribution of cytokines and immune cells to catabolic and nociceptive processes provide new targets for treating symptomatic disc disease. PMID:24166242

  10. The effect of two artificial salivas on the adhesion of Candida albicans to heat-polymerized acrylic resin

    PubMed Central

    2015-01-01

    PURPOSE Xerostomia can diminish the quality of life, leads to changes in normal chemical composition of saliva and oral microbiata, and increases the risk for opportunistic infections, such as Candida albicans. Various artificial salivas have been considered for patients with xerostomia. However, the knowledge on the antifungal and antiadhesive activity of artificial saliva substitutes is limited. The aim of the present study was to evaluate influence of two artificial salivas on the adhesion of Candida albicans to the polymethylmethacrylate disc specimens. MATERIALS AND METHODS Two commercial artificial salivas (Saliva Orthana and Biotene Oral Balance Gel) were selected. 45 polymethylmethacrylate disc specimens were prepared and randomly allocated into 3 groups; Saliva Orthana, Biotene-Oral Balance gel and distilled water. Specimens were stored in the artificial saliva or in the sterile distilled water for 60 minutes at 37℃. Then they were exposed to yeast suspensions including Candida albicans. Yeast cells were counted using ×40 magnification under a light microscope and data were analysed. RESULTS Analysis of data indicated statistically significant difference in adhesion of Candida albicans among all experimental groups (P=.000). Findings indicated that Saliva Orthana had higher adhesion scores than the Biotene Oral Balance gel and distilled water (P<.05). CONCLUSION In comparison of Saliva Orthana, the use of Biotene Oral Balance Gel including lysozyme, lactoferrin and peroxidase may be an appropriate treatment method to prevent of adhesion of Candida albicans and related infections in patients with xerostomia. PMID:25932306

  11. Disrupted in schizophrenia 1 (DISC1) L100P mutants have impaired activity-dependent plasticity in vivo and in vitro.

    PubMed

    Tropea, D; Molinos, I; Petit, E; Bellini, S; Nagakura, I; O'Tuathaigh, C; Schorova, L; Mitchell, K J; Waddington, J; Sur, M; Gill, M; Corvin, A P

    2016-01-01

    Major neuropsychiatric disorders are genetically complex but share overlapping etiology. Mice mutant for rare, highly penetrant risk variants can be useful in dissecting the molecular mechanisms involved. The gene disrupted in schizophrenia 1 (DISC1) has been associated with increased risk for neuropsychiatric conditions. Mice mutant for Disc1 display morphological, functional and behavioral deficits that are consistent with impairments observed across these disorders. Here we report that Disc1 L100P mutants are less able to reorganize cortical circuitry in response to stimulation in vivo. Molecular analysis reveals that the mutants have a reduced expression of PSD95 and pCREB in visual cortex and fail to adjust expression of such markers in response to altered stimulation. In vitro analysis shows that mutants have impaired functional reorganization of cortical neurons in response to selected forms of neuronal stimulation, but there is no altered basal expression of synaptic markers. These findings suggest that DISC1 has a critical role in the reorganization of cortical plasticity and that this phenotype becomes evident only under challenge, even at early postnatal stages. This result may represent an important etiological mechanism in the emergence of neuropsychiatric disorders. PMID:26756905

  12. Two-dimensional artificial light-harvesting antennae with predesigned high-order structure and robust photosensitising activity.

    PubMed

    Feng, Xiao; Ding, Xuesong; Chen, Long; Wu, Yang; Liu, Lili; Addicoat, Matthew; Irle, Stephan; Dong, Yuping; Jiang, Donglin

    2016-01-01

    Highly ordered discrete assemblies of chlorophylls that are found in natural light-harvesting antennae are key to photosynthesis, which converts light energy to chemical energy and is the principal producer of organic matter on Earth. Porphyrins and phthalocyanines, which are analogues of chlorophylls, exhibit a strong absorbance of visible and near-infrared light, respectively. A highly ordered porphyrin-co-phthalocyanine antennae would harvest photons over the entire solar spectrum for chemical transformation. However, such a robust antennae has not yet been synthesised. Herein, we report a strategy that merges covalent bonds and noncovalent forces to produce highly ordered two-dimensional porphyrin-co-phthalocyanine antennae. This methodology enables control over the stoichiometry and order of the porphyrin and phthalocyanine units; more importantly, this approach is compatible with various metalloporphyrin and metallophthalocyanine derivatives and thus may lead to the generation of a broad structural diversity of two-dimensional artificial antennae. These ordered porphyrin-co-phthalocyanine two-dimensional antennae exhibit unique optical properties and catalytic functions that are not available with single-component or non-structured materials. These 2D artificial antennae exhibit exceptional light-harvesting capacity over the entire solar spectrum as a result of a synergistic light-absorption effect. In addition, they exhibit outstanding photosensitising activities in using both visible and near-infrared photons for producing singlet oxygen. PMID:27622274

  13. Artificial Hydrogenases

    PubMed Central

    Barton, Bryan E.; Olsen, Matthew T.; Rauchfuss, Thomas B.

    2010-01-01

    Decades of biophysical study on the hydrogenase (H2ase) enzymes have yielded sufficient information to guide the synthesis of analogues of their active sites. Three families of enzymes serve as inspiration for this work: the [FeFe]-, [NiFe]-, and [Fe]-H2ases, all of which feature iron centers bound to both CO and thiolate. Artificial H2ases effect the oxidation of H2 of H2 and the reverse reaction, the reduction of protons. These reactions occur via the intermediacy of metal hydrides. The inclusion of amine bases within the catalysts is an important design feature that is emulated in related bioinspired catalysts. Continuing challenges are the low reactivity of H2 towards biomimetic H2ases. PMID:20356731

  14. Artificial rheotaxis

    PubMed Central

    Palacci, Jérémie; Sacanna, Stefano; Abramian, Anaïs; Barral, Jérémie; Hanson, Kasey; Grosberg, Alexander Y.; Pine, David J.; Chaikin, Paul M.

    2015-01-01

    Motility is a basic feature of living microorganisms, and how it works is often determined by environmental cues. Recent efforts have focused on developing artificial systems that can mimic microorganisms, in particular their self-propulsion. We report on the design and characterization of synthetic self-propelled particles that migrate upstream, known as positive rheotaxis. This phenomenon results from a purely physical mechanism involving the interplay between the polarity of the particles and their alignment by a viscous torque. We show quantitative agreement between experimental data and a simple model of an overdamped Brownian pendulum. The model notably predicts the existence of a stagnation point in a diverging flow. We take advantage of this property to demonstrate that our active particles can sense and predictably organize in an imposed flow. Our colloidal system represents an important step toward the realization of biomimetic microsystems with the ability to sense and respond to environmental changes. PMID:26601175

  15. Artificial rheotaxis.

    PubMed

    Palacci, Jérémie; Sacanna, Stefano; Abramian, Anaïs; Barral, Jérémie; Hanson, Kasey; Grosberg, Alexander Y; Pine, David J; Chaikin, Paul M

    2015-05-01

    Motility is a basic feature of living microorganisms, and how it works is often determined by environmental cues. Recent efforts have focused on developing artificial systems that can mimic microorganisms, in particular their self-propulsion. We report on the design and characterization of synthetic self-propelled particles that migrate upstream, known as positive rheotaxis. This phenomenon results from a purely physical mechanism involving the interplay between the polarity of the particles and their alignment by a viscous torque. We show quantitative agreement between experimental data and a simple model of an overdamped Brownian pendulum. The model notably predicts the existence of a stagnation point in a diverging flow. We take advantage of this property to demonstrate that our active particles can sense and predictably organize in an imposed flow. Our colloidal system represents an important step toward the realization of biomimetic microsystems with the ability to sense and respond to environmental changes. PMID:26601175

  16. Moving-mesh cosmology: properties of gas discs

    NASA Astrophysics Data System (ADS)

    Torrey, Paul; Vogelsberger, Mark; Sijacki, Debora; Springel, Volker; Hernquist, Lars

    2012-12-01

    We compare the structural properties of galaxies formed in cosmological simulations using the smoothed particle hydrodynamics (SPH) code GADGET with those using the moving-mesh code AREPO. Both codes employ identical gravity solvers and the same subresolution physics but use very different methods to track the hydrodynamic evolution of gas. This permits us to isolate the effects of the hydro solver on the formation and evolution of galactic gas discs in GADGET and AREPO haloes with comparable numerical resolution. In a matching sample of GADGET and AREPO haloes, we fit simulated gas discs with exponential profiles. We find that the cold gas discs formed using the moving-mesh approach have systematically larger disc scale lengths and higher specific angular momenta than their GADGET counterparts across a wide range in halo masses. For low-mass galaxies, differences between the properties of the simulated galaxy discs are caused by an insufficient number of resolution elements which lead to the artificial angular momentum transfer in our SPH calculation. We however find that galactic discs formed in massive haloes, resolved with ≥106 particles/cells, are still systematically smaller in the GADGET run by a factor of ˜2. The reason for this is twofold: (i) the excessive heating of haloes close to the cooling radius due to spurious dissipation of the subsonic turbulence in GADGET reduces the supply of gas which can cool and settle on to the central disc; (ii) the efficient delivery of low angular momentum gaseous blobs to the bottom of the potential well results in the centrally concentrated gas discs in GADGET simulation. While this large population of gaseous blobs in GADGET originates from the filaments which are pressure confined and fragment due to the SPH surface tension while infalling into hot halo atmospheres, it is essentially absent in the moving-mesh calculation, clearly indicating numerical rather than physical origin of the blob material.

  17. Biomechanics of Disc Degeneration

    PubMed Central

    Palepu, V.; Kodigudla, M.; Goel, V. K.

    2012-01-01

    Disc degeneration and associated disorders are among the most debated topics in the orthopedic literature over the past few decades. These may be attributed to interrelated mechanical, biochemical, and environmental factors. The treatment options vary from conservative approaches to surgery, depending on the severity of degeneration and response to conservative therapies. Spinal fusion is considered to be the “gold standard” in surgical methods till date. However, the association of adjacent level degeneration has led to the evolution of motion preservation technologies like spinal arthroplasty and posterior dynamic stabilization systems. These new technologies are aimed to address pain and preserve motion while maintaining a proper load sharing among various spinal elements. This paper provides an elaborative biomechanical review of the technologies aimed to address the disc degeneration and reiterates the point that biomechanical efficacy followed by long-term clinical success will allow these nonfusion technologies as alternatives to fusion, at least in certain patient population. PMID:22745914

  18. LUMBAR DISC HERNIATION

    PubMed Central

    Vialle, Luis Roberto; Vialle, Emiliano Neves; Suárez Henao, Juan Esteban; Giraldo, Gustavo

    2015-01-01

    Lumbar disc herniation is the most common diagnosis among the degenerative abnormalities of the lumbar spine (affecting 2 to 3% of the population), and is the principal cause of spinal surgery among the adult population. The typical clinical picture includes initial lumbalgia, followed by progressive sciatica. The natural history of disc herniation is one of rapid resolution of the symptoms (four to six weeks). The initial treatment should be conservative, managed through medication and physiotherapy, sometimes associated with percutaneous nerve root block. Surgical treatment is indicated if pain control is unsuccessful, if there is a motor deficit greater than grade 3, if there is radicular pain associated with foraminal stenosis, or if cauda equina syndrome is present. The latter represents a medical emergency. A refined surgical technique, with removal of the extruded fragment and preservation of the ligamentum flavum, resolves the sciatic symptoms and reduces the risk of recurrence over the long term. PMID:27019834

  19. Is artificial recharge promoting microbial activity and biodegradation processes in groundwater systems?

    NASA Astrophysics Data System (ADS)

    Barba Ferrer, Carme; Folch, Albert; Gaju, Núria; Martínez-Alonso, Maira; Carrasquilla, Marc; Grau-Martínez, Alba; Sanchez-Vila, Xavier

    2016-04-01

    Managed Artificial Recharge (MAR) represents a strategic tool for managing water resources, especially during scarce periods. On one hand, it can increase water stored in aquifers and extract it when weather conditions do not permit exclusive exploitation of surface resources. On the other, it allows improve water quality due the processes occurring into the soil whereas water crosses vadose zone. Barcelona (Catalonia, Spain) conurbation is suffering significant quantitative and qualitative groundwater disturbances. For this reason, Sant Vicenç MAR system, constituted by a sedimentation and an infiltration pond, was constructed in 2009 as the strategic water management infrastructure. Compared with other MAR facilities, this infiltration pond has a reactive bed formed by organic compost and local material. The objective is to promote different redox states allowing more and different degradation of chemical compounds than regular MAR systems. In previous studies in the site, physical and hydrochemical parameters demonstrated that there was indeed a degradation of different pollutants. However, to go a step further understanding the different biogeochemical processes and the related degradation processes occurring in the system, we studied the existing microbial communities. So, molecular techniques were applied in water and soil samples in two different scenarios; the first one, when the system was fully operating and the second when the system was not operating during some months. We have specifically compared microbial diversity and richness indexes and both cluster dendrograms obtained from DGGEs analysis made in each sampling campaign.

  20. Effectiveness of Photogem® activated by LED on the decontamination of artificial carious bovine dentin

    NASA Astrophysics Data System (ADS)

    Giusti, J. S. M.; Santos-Pinto, L.; Pizzolitto, A. C.; Kurachi, C.; Bagnato, V. S.

    2006-05-01

    The aim of this study was the evaluation of the effectiveness of photodynamic therapy on the decontamination of artificially induced carious bovine dentin, using Photogem® as the photosensitizer agent and an LED device as a light source. Dentin samples obtained from bovine incisors were immersed in sterile broth supplemented by Lactobacillus acidophillus 108 colony formation units (CFU) and Streptococcus mutans 108 CFU. Different concentrations of photosensitizer, PA = 1 mg/ml, PB = 2 mg/ml, and PC = 3 mg/ml, and two fluences, D = 24 J/cm2 and D = 48 J/cm2, were investigated. After CFU counting per milligram of carious dentin and statistical analysis, we observed that the photodynamic therapy (PDT) parameters used were effective for bacterial reduction in the in vitro model under study. The best result was achieved with the application of Photogem® at 2 mg/ml and photoactivated under 24 J/cm2 showing a survival factor of 0.14. At higher photosensitizer concentrations, a higher dark toxicity was observed. We propose a simple mathematical expression for the determination of PDT parameters of photosensitizer concentration and light fluence for different survival factor values. Since LED devices are simpler and cheaper compared to laser systems, it would be interesting to verify their efficacy as a light source in photodynamic therapy for the decontamination of carious dentin.

  1. Total disc replacement.

    PubMed

    Vital, J-M; Boissière, L

    2014-02-01

    Total disc replacement (TDR) (partial disc replacement will not be described) has been used in the lumbar spine since the 1980s, and more recently in the cervical spine. Although the biomechanical concepts are the same and both are inserted through an anterior approach, lumbar TDR is conventionally indicated for chronic low back pain, whereas cervical TDR is used for soft discal hernia resulting in cervicobrachial neuralgia. The insertion technique must be rigorous, with precise centering in the disc space, taking account of vascular anatomy, which is more complex in the lumbar region, particularly proximally to L5-S1. All of the numerous studies, including prospective randomized comparative trials, have demonstrated non-inferiority to fusion, or even short-term superiority regarding speed of improvement. The main implant-related complication is bridging heterotopic ossification with resulting loss of range of motion and increased rates of adjacent segment degeneration, although with an incidence lower than after arthrodesis. A sufficiently long follow-up, which has not yet been reached, will be necessary to establish definitively an advantage for TDR, particularly in the cervical spine. PMID:24412045

  2. Biomechanical comparison between lumbar disc arthroplasty and fusion.

    PubMed

    Chen, Shih-Hao; Zhong, Zheng-Cheng; Chen, Chen-Sheng; Chen, Wen-Jer; Hung, Chinghua

    2009-03-01

    The artificial disc is a mobile implant for degenerative disc replacement that attempts to lessen the degeneration of the adjacent elements. However, inconsistent biomechanical results for the neighboring elements have been reported in a number of studies. The present study used finite element (FE) analysis to explore the biomechanical differences at the surgical and both adjacent levels following artificial disc replacement and interbody fusion procedures. First, a three-dimensional FE model of a five-level lumbar spine was established by the commercially available medical imaging software Amira 3.1.1, and FE software ANSYS 9.0. After validating the five-level intact (INT) model with previous in vitro studies, the L3/L4 level of the INT model was modified to either insert an artificial disc (ProDisc II; ADR) or incorporate bilateral posterior lumbar interbody fusion (PLIF) cages with a pedicle screw fixation system. All models were constrained at the bottom of the L5 vertebra and subjected to 150N preload and 10Nm moments under four physiological motions. The ADR model demonstrated higher range of motion (ROM), annulus stress, and facet contact pressure at the surgical level compared to the non-modified INT model. At both adjacent levels, ROM and annulus stress were similar to that of the INT model and varied less than 7%. In addition, the greatest displacement of posterior annulus occurred at the superior-lateral region. Conversely, the PLIF model showed less ROM, less annulus stress, and no facet contact pressure at the surgical level compared to the INT model. The adjacent levels had obviously high ROM, annulus stress, and facet contact pressure, especially at the adjacent L2/3 level. In conclusion, the artificial disc replacement revealed no adjacent-level instability. However, instability was found at the surgical level, which might accelerate degeneration at the highly stressed annulus and facet joint. In contrast to disc replacement results, the posterior

  3. Hourly photosynthetically active radiation estimation in Midwestern United States from artificial neural networks and conventional regressions models.

    PubMed

    Yu, Xiaolei; Guo, Xulin

    2016-08-01

    The relationship between hourly photosynthetically active radiation (PAR) and the global solar radiation (R s ) was analyzed from data gathered over 3 years at Bondville, IL, and Sioux Falls, SD, Midwestern USA. These data were used to determine temporal variability of the PAR fraction and its dependence on different sky conditions, which were defined by the clearness index. Meanwhile, models based on artificial neural networks (ANNs) were established for predicting hourly PAR. The performance of the proposed models was compared with four existing conventional regression models in terms of the normalized root mean square error (NRMSE), the coefficient of determination (r (2)), the mean percentage error (MPE), and the relative standard error (RSE). From the overall analysis, it shows that the ANN model can predict PAR accurately, especially for overcast sky and clear sky conditions. Meanwhile, the parameters related to water vapor do not improve the prediction result significantly. PMID:26715137

  4. Hourly photosynthetically active radiation estimation in Midwestern United States from artificial neural networks and conventional regressions models

    NASA Astrophysics Data System (ADS)

    Yu, Xiaolei; Guo, Xulin

    2016-08-01

    The relationship between hourly photosynthetically active radiation (PAR) and the global solar radiation ( R s ) was analyzed from data gathered over 3 years at Bondville, IL, and Sioux Falls, SD, Midwestern USA. These data were used to determine temporal variability of the PAR fraction and its dependence on different sky conditions, which were defined by the clearness index. Meanwhile, models based on artificial neural networks (ANNs) were established for predicting hourly PAR. The performance of the proposed models was compared with four existing conventional regression models in terms of the normalized root mean square error (NRMSE), the coefficient of determination ( r 2), the mean percentage error (MPE), and the relative standard error (RSE). From the overall analysis, it shows that the ANN model can predict PAR accurately, especially for overcast sky and clear sky conditions. Meanwhile, the parameters related to water vapor do not improve the prediction result significantly.

  5. Studying the explanatory capacity of artificial neural networks for understanding environmental chemical quantitative structure-activity relationship models.

    PubMed

    Yang, Lei; Wang, Peng; Jiang, Yilin; Chen, Jian

    2005-01-01

    Although artificial neural networks (ANNs) have been shown to exhibit superior predictive power in the study of quantitative structure-activity relationships (QSARs), they have also been labeled a "black box" because they provide little explanatory insight into the relative influence of the independent variables in the predictive process so that little information on how and why compounds work can be obtained. Here, we have turned our interests to their explanatory capacities; therefore, a method was proposed for assessing the relative importance of variables indicating molecular structure, on the basis of axon connection weights and partial derivatives of the ANN output with respect to its input, which can identify variables that significantly contribute to network predictions, and providing a variable selection method for ANNs. We show that, by extending this approach to ANNs, the "black box" mechanics of ANNs can be greatly illuminated, thereby making it very useful in understanding environmental chemical QSAR models. PMID:16309287

  6. Hourly photosynthetically active radiation estimation in Midwestern United States from artificial neural networks and conventional regressions models

    NASA Astrophysics Data System (ADS)

    Yu, Xiaolei; Guo, Xulin

    2015-12-01

    The relationship between hourly photosynthetically active radiation (PAR) and the global solar radiation (R s ) was analyzed from data gathered over 3 years at Bondville, IL, and Sioux Falls, SD, Midwestern USA. These data were used to determine temporal variability of the PAR fraction and its dependence on different sky conditions, which were defined by the clearness index. Meanwhile, models based on artificial neural networks (ANNs) were established for predicting hourly PAR. The performance of the proposed models was compared with four existing conventional regression models in terms of the normalized root mean square error (NRMSE), the coefficient of determination (r 2), the mean percentage error (MPE), and the relative standard error (RSE). From the overall analysis, it shows that the ANN model can predict PAR accurately, especially for overcast sky and clear sky conditions. Meanwhile, the parameters related to water vapor do not improve the prediction result significantly.

  7. Induction of sexual activity in lactating anovulatory female goats using male goats treated only with artificially long days.

    PubMed

    Delgadillo, J A; Flores, J A; Véliz, F G; Hernández, H F; Duarte, G; Vielma, J; Poindron, P; Chemineau, P; Malpaux, B

    2002-11-01

    contact with LD-treated males ovulated and showed at least one estrous behavior during the 15 d following joining (P < 0.001). These results indicate that the sexual activity of male goats from subtropical latitudes can be induced using only artificially long days. In addition, males treated in this way are capable of stimulating sexual activity in anovulatory females by the male effect. PMID:12462243

  8. Counter-rotating accretion discs

    NASA Astrophysics Data System (ADS)

    Dyda, S.; Lovelace, R. V. E.; Ustyugova, G. V.; Romanova, M. M.; Koldoba, A. V.

    2015-01-01

    Counter-rotating discs can arise from the accretion of a counter-rotating gas cloud on to the surface of an existing corotating disc or from the counter-rotating gas moving radially inwards to the outer edge of an existing disc. At the interface, the two components mix to produce gas or plasma with zero net angular momentum which tends to free-fall towards the disc centre. We discuss high-resolution axisymmetric hydrodynamic simulations of viscous counter-rotating discs for the cases where the two components are vertically separated and radially separated. The viscosity is described by an isotropic α-viscosity including all terms in the viscous stress tensor. For the vertically separated components, a shear layer forms between them and the middle part of this layer free-falls to the disc centre. The accretion rates are increased by factors of ˜102-104 over that for a conventional disc rotating in one direction with the same viscosity. The vertical width of the shear layer and the accretion rate are strongly dependent on the viscosity and the mass fraction of the counter-rotating gas. In the case of radially separated components where the inner disc corotates and the outer disc rotates in the opposite direction, a gap between the two components opens and closes quasi-periodically. The accretion rates are ≳25 times larger than those for a disc rotating in one direction with the same viscosity.

  9. Have protoplanetary discs formed planets?

    NASA Astrophysics Data System (ADS)

    Greaves, J. S.; Rice, W. K. M.

    2010-09-01

    It has recently been noted that many discs around T Tauri stars appear to comprise only a few Jupiter masses of gas and dust. Using millimetre surveys of discs within six local star formation regions, we confirm this result, and find that only a few per cent of young stars have enough circumstellar material to build gas giant planets, in standard core accretion models. Since the frequency of observed exoplanets is greater than this, there is a `missing-mass' problem. As alternatives to simply adjusting the conversion of dust flux to disc mass, we investigate three other classes of solution. Migration of planets could hypothetically sweep up the disc mass reservoir more efficiently, but trends in multiplanet systems do not support such a model, and theoretical models suggest that the gas accretion time-scale is too short for migration to sweep the disc. Enhanced inner-disc mass reservoirs are possible, agreeing with predictions of disc evolution through self-gravity, but not adding to millimetre dust flux as the inner disc is optically thick. Finally, the incidence of massive discs is shown to be higher at the protostellar stages, Classes 0 and I, where discs substantial enough to form planets via core accretion are abundant enough to match the frequency of exoplanets. Gravitational instability may also operate in the Class 0 epoch, where half the objects have potentially unstable discs of >~30 per cent of the stellar mass. However, recent calculations indicate that forming gas giants inside 50 au by instability is unlikely, even in such massive discs. Overall, the results presented suggest that the canonically `protoplanetary' discs of Class II T Tauri stars have globally low masses in dust observable at millimetre wavelengths, and conversion to larger bodies (anywhere from small rocks up to planetary cores) must already have occurred.

  10. Dust dynamics in 2D gravito-turbulent discs

    NASA Astrophysics Data System (ADS)

    Shi, Ji-Ming; Zhu, Zhaohuan; Stone, James M.; Chiang, Eugene

    2016-06-01

    The dynamics of solid bodies in protoplanetary discs are subject to the properties of any underlying gas turbulence. Turbulence driven by disc self-gravity shows features distinct from those driven by the magnetorotational instability (MRI). We study the dynamics of solids in gravito-turbulent discs with two-dimensional (in the disc plane), hybrid (particle and gas) simulations. Gravito-turbulent discs can exhibit stronger gravitational stirring than MRI-active discs, resulting in greater radial diffusion and larger eccentricities and relative speeds for large particles (those with dimensionless stopping times tstopΩ > 1, where Ω is the orbital frequency). The agglomeration of large particles into planetesimals by pairwise collisions is therefore disfavoured in gravito-turbulent discs. However, the relative speeds of intermediate-size particles (tstopΩ ˜ 1) are significantly reduced as such particles are collected by gas drag and gas gravity into coherent filament-like structures with densities high enough to trigger gravitational collapse. First-generation planetesimals may form via gravitational instability of dust in marginally gravitationally unstable gas discs.

  11. Artificial neural network--based analysis of high-throughput screening data for improved prediction of active compounds.

    PubMed

    Chakrabarti, Swapan; Svojanovsky, Stan R; Slavik, Romana; Georg, Gunda I; Wilson, George S; Smith, Peter G

    2009-12-01

    Artificial neural networks (ANNs) are trained using high-throughput screening (HTS) data to recover active compounds from a large data set. Improved classification performance was obtained on combining predictions made by multiple ANNs. The HTS data, acquired from a methionine aminopeptidases inhibition study, consisted of a library of 43,347 compounds, and the ratio of active to nonactive compounds, R(A/N), was 0.0321. Back-propagation ANNs were trained and validated using principal components derived from the physicochemical features of the compounds. On selecting the training parameters carefully, an ANN recovers one-third of all active compounds from the validation set with a 3-fold gain in R(A/N) value. Further gains in R(A/N) values were obtained upon combining the predictions made by a number of ANNs. The generalization property of the back-propagation ANNs was used to train those ANNs with the same training samples, after being initialized with different sets of random weights. As a result, only 10% of all available compounds were needed for training and validation, and the rest of the data set was screened with more than a 10-fold gain of the original R(A/N) value. Thus, ANNs trained with limited HTS data might become useful in recovering active compounds from large data sets. PMID:19940083

  12. Disc edge veins of Kraupa associated with optic disc drusen

    PubMed Central

    Díaz, Andrea; Almela, Miguel Angel

    2014-01-01

    Objective: Disc edge veins of Kraupa are a rare anomaly of the retinal venous system in which the main trunk of the retinal vein disappeared into the margin of the optic disc instead of its centre. Methods: A 40-year-old woman was detected to have an anomaly in her left optic disc in a routine eye examination. The eyes had an anomaly of the retinal venous system in which all branches of the retinal vein joined in a common trunk that entered the disc margin inferonasally. The central retinal artery issued from the centre of the disc separately of the venous system. B-scan ultrasonografhy revealed the presence of hyperechoic imaging at the optic nerve head in both eyes. Results: We describe the association of disc edge veins of Kraupa with optic disc drusen. Conclusion: Vascular complications of optic disc drusen hav been described. We don’t know the implication of disc edge veins in the pathogenesis of these complications.

  13. Enclosed rotary disc air pulser

    DOEpatents

    Olson, A. L.; Batcheller, Tom A.; Rindfleisch, J. A.; Morgan, John M.

    1989-01-01

    An enclosed rotary disc air pulser for use with a solvent extraction pulse olumn includes a housing having inlet, exhaust and pulse leg ports, a shaft mounted in the housing and adapted for axial rotation therein, first and second disc members secured to the shaft within the housing in spaced relation to each other to define a chamber therebetween, the chamber being in communication with the pulse leg port, the first disc member located adjacent the inlet port, the second disc member being located adjacent the exhaust port, each disc member having a milled out portion, the disc members positioned on the shaft so that as the shaft rotates, the milled out portions permit alternative cyclical communication between the inlet port and the chamber and the exhaust port and the chamber.

  14. Edge-on thick discs

    NASA Astrophysics Data System (ADS)

    Kasparova, A.; Katkov, I.; Chilingarian, I.; Silchenko, O.; Moiseev, A.; Borisov, S.

    2016-06-01

    Although thick stellar discs are detected in nearly all edge-on disc galaxies, their formation scenarios still remain a matter of debate. Due to observational difficulties, there is a lack of information about their stellar populations. Using the Russian 6-m telescope BTA we collected deep spectra of thick discs in three edge-on early-type disc galaxies located in different environments: NGC4111 in a dense group, NGC4710 in the Virgo cluster, and NGC5422 in a sparse group. We see intermediate age (4 ‑ 5 Gyr) metal rich ([Fe/H] ~ ‑0.2 ‑ 0.0 dex) stellar populations in NGC4111 and NGC4710. On the other hand, NGC5422 does not harbour young stars, its only disc is thick and old (10 Gyr) and its α-element abundance suggests a long formation epoch implying its formation at high redshift. Our results prove the diversity of thick disc formation scenarios.

  15. Language experience shapes fusiform activation when processing a logographic artificial language: an fMRI training study.

    PubMed

    Xue, Gui; Chen, Chuansheng; Jin, Zhen; Dong, Qi

    2006-07-01

    The significant role of the left midfusiform cortex in reading found in recent neuroimaging studies has led to the visual word form area (VWFA) hypothesis. This hypothesis suggests that years of experience reading native language change the visual expertise of this region to be especially sensitive to the visual form of native language. The present study aimed at testing this hypothesis by exploring the role of language experience in shaping the fusiform activation. We designed a logographic artificial language (LAL) using the visual form and pronunciation of Korean Hangul characters (but their correspondence was shuffled) and assigning arbitrary meanings to these characters. Twelve native Chinese Mandarin speakers (6 male and 6 female, 18 to 21 years old) with no prior knowledge of Korean language were trained in the visual form of these characters for 2 weeks, followed by 2 weeks each of phonological and semantic training. Behavioral data indicated that training was effective in increasing the efficiency of visual form processing and establishing the connections among visual form, sounds, and meanings. Imaging data indicated that at the pre-training stage, subjects showed stronger activation in the fusiform regions for LAL than for Chinese across both one-back visual matching task and the passive viewing task. Visual form training significantly decreased the activation of bilateral fusiform cortex and the left inferior occipital cortex, whereas phonological training increased activation in these regions, and the right fusiform remained more active after semantic training. Increased activations after phonological and semantic training were also evident in other regions involved in language processing. These findings thus do not seem to be consistent with the visual-expertise-induced-sensitivity hypothesis about fusiform regions. Instead, our results suggest that visual familiarity, phonological processing, and semantic processing all make significant but different

  16. Artificial Intelligence.

    ERIC Educational Resources Information Center

    Thornburg, David D.

    1986-01-01

    Overview of the artificial intelligence (AI) field provides a definition; discusses past research and areas of future research; describes the design, functions, and capabilities of expert systems and the "Turing Test" for machine intelligence; and lists additional sources for information on artificial intelligence. Languages of AI are also briefly…

  17. Artificial Intelligence.

    ERIC Educational Resources Information Center

    Smith, Linda C.; And Others

    1988-01-01

    A series of articles focuses on artificial intelligence research and development to enhance information systems and services. Topics discussed include knowledge base designs, expert system development tools, natural language processing, expert systems for reference services, and the role that artificial intelligence concepts should have in…

  18. Artificial intelligence

    SciTech Connect

    Firschein, O.

    1984-01-01

    This book presents papers on artificial intelligence. Topics considered include knowledge engineering, expert systems, applications of artificial intelligence to scientific reasoning, planning and problem solving, error recovery in robots through failure reason analysis, programming languages, natural language, speech recognition, map-guided interpretation of remotely-sensed imagery, and image understanding architectures.

  19. Total disc replacement surgery for symptomatic degenerative lumbar disc disease: a systematic review of the literature.

    PubMed

    van den Eerenbeemt, Karin D; Ostelo, Raymond W; van Royen, Barend J; Peul, Wilco C; van Tulder, Maurits W

    2010-08-01

    The objective of this study is to evaluate the effectiveness and safety of total disc replacement surgery compared with spinal fusion in patients with symptomatic lumbar disc degeneration. Low back pain (LBP), a major health problem in Western countries, can be caused by a variety of pathologies, one of which is degenerative disc disease (DDD). When conservative treatment fails, surgery might be considered. For a long time, lumbar fusion has been the "gold standard" of surgical treatment for DDD. Total disc replacement (TDR) has increased in popularity as an alternative for lumbar fusion. A comprehensive systematic literature search was performed up to October 2008. Two reviewers independently checked all retrieved titles and abstracts, and relevant full text articles for inclusion. Two reviewers independently assessed the risk of bias of included studies and extracted relevant data and outcomes. Three randomized controlled trials and 16 prospective cohort studies were identified. In all three trials, the total disc replacement was compared with lumbar fusion techniques. The Charité trial (designed as a non-inferiority trail) was considered to have a low risk of bias for the 2-year follow up, but a high risk of bias for the 5-year follow up. The Charité artificial disc was non-inferior to the BAK Interbody Fusion System on a composite outcome of "clinical success" (57.1 vs. 46.5%, for the 2-year follow up; 57.8 vs. 51.2% for the 5-year follow up). There were no statistically significant differences in mean pain and physical function scores. The Prodisc artificial disc (also designed as a non-inferiority trail) was found to be statistically significant more effective when compared with the lumbar circumferential fusion on the composite outcome of "clinical success" (53.4 vs. 40.8%), but the risk of bias of this study was high. Moreover, there were no statistically significant differences in mean pain and physical function scores. The Flexicore trial, with a high

  20. Total disc replacement surgery for symptomatic degenerative lumbar disc disease: a systematic review of the literature

    PubMed Central

    van den Eerenbeemt, Karin D.; van Royen, Barend J.; Peul, Wilco C.; van Tulder, Maurits W.

    2010-01-01

    The objective of this study is to evaluate the effectiveness and safety of total disc replacement surgery compared with spinal fusion in patients with symptomatic lumbar disc degeneration. Low back pain (LBP), a major health problem in Western countries, can be caused by a variety of pathologies, one of which is degenerative disc disease (DDD). When conservative treatment fails, surgery might be considered. For a long time, lumbar fusion has been the “gold standard” of surgical treatment for DDD. Total disc replacement (TDR) has increased in popularity as an alternative for lumbar fusion. A comprehensive systematic literature search was performed up to October 2008. Two reviewers independently checked all retrieved titles and abstracts, and relevant full text articles for inclusion. Two reviewers independently assessed the risk of bias of included studies and extracted relevant data and outcomes. Three randomized controlled trials and 16 prospective cohort studies were identified. In all three trials, the total disc replacement was compared with lumbar fusion techniques. The Charité trial (designed as a non-inferiority trail) was considered to have a low risk of bias for the 2-year follow up, but a high risk of bias for the 5-year follow up. The Charité artificial disc was non-inferior to the BAK® Interbody Fusion System on a composite outcome of “clinical success” (57.1 vs. 46.5%, for the 2-year follow up; 57.8 vs. 51.2% for the 5-year follow up). There were no statistically significant differences in mean pain and physical function scores. The Prodisc artificial disc (also designed as a non-inferiority trail) was found to be statistically significant more effective when compared with the lumbar circumferential fusion on the composite outcome of “clinical success” (53.4 vs. 40.8%), but the risk of bias of this study was high. Moreover, there were no statistically significant differences in mean pain and physical function scores. The Flexicore trial

  1. Dynamics of structures in active suspensions of paramagnetic particles and applications to artificial micro-swimmers

    NASA Astrophysics Data System (ADS)

    Keaveny, Eric Edward

    Micron-size paramagnetic particles suspended in viscous fluid will aggregate to form linear chains when subject to a uniform magnetic field. This process provides a way of changing the rheological properties of a suspension or building structures for microfluidic devices. We present a method to efficiently and accurately quantify the magnetic interactions between these particles. With this model and the force-coupling method, we perform simulations of both small ensembles and suspensions of thousands of paramagnetic particles subject to shear flows or rotating applied magnetic fields and demonstrate that in these situations an accurate representation of the fluid forces is necessary to estimate chain length. The artificial micro-swimmer is a device constructed from a flagellum-like tail of chemically linked paramagnetic beads tethered to a human red blood cell. To simulate this device, we develop an elastic coupling model that treats each chemical link as an inextensible, flexible rod. We demonstrate that when this device is subject to a rotating applied magnetic field, the filament tail will deform into a helical shape rotating with the field and propel the swimmer through the viscous fluid. Using a continuous elastica/resistive force model, we explore further the dependence of the swimming speed on the magnetic forces and swimmer geometry in the low frequency limit. We then examine the interactions between two comoving swimmers and ascertain at what separation distance a far-field approximation of the hydrodynamics is sufficient to reproduce the swimmers' dynamics. We also provide simulations of a single swimmer near a rigid surface and demonstrate that under certain conditions the presence of a wall can enhance the swimming speed. We determine further the height dependence of the repulsion from the surface, and, in the case of the spiral swimmer, the lateral drift speed. Finally, we consider a "squirmer" model for a swimming microorganism, appropriate for

  2. Application of artificial neural network in precise prediction of cement elements percentages based on the neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Eftekhari Zadeh, E.; Feghhi, S. A. H.; Roshani, G. H.; Rezaei, A.

    2016-05-01

    Due to variation of neutron energy spectrum in the target sample during the activation process and to peak overlapping caused by the Compton effect with gamma radiations emitted from activated elements, which results in background changes and consequently complex gamma spectrum during the measurement process, quantitative analysis will ultimately be problematic. Since there is no simple analytical correlation between peaks' counts with elements' concentrations, an artificial neural network for analyzing spectra can be a helpful tool. This work describes a study on the application of a neural network to determine the percentages of cement elements (mainly Ca, Si, Al, and Fe) using the neutron capture delayed gamma-ray spectra of the substance emitted by the activated nuclei as patterns which were simulated via the Monte Carlo N-particle transport code, version 2.7. The Radial Basis Function (RBF) network is developed with four specific peaks related to Ca, Si, Al and Fe, which were extracted as inputs. The proposed RBF model is developed and trained with MATLAB 7.8 software. To obtain the optimal RBF model, several structures have been constructed and tested. The comparison between simulated and predicted values using the proposed RBF model shows that there is a good agreement between them.

  3. Numbered nasal discs for waterfowl

    USGS Publications Warehouse

    Bartonek, J.C.; Dane, C.W.

    1964-01-01

    Numbered nasal discs were successfully used in studies requiring large numbers of individually marked waterfowl. The procedure for constructing these discs is outlined. Blue-winged teal (Anas discors) with 5/8-inch discs, and canvasback (Aythya valisineria) and redhead (A. americana) with 3/4-inch discs can be individually identified up to 50 and 80 yards, respectively, with a gunstock-mounted, 20-power spotting scope. The particular value of these markers is their durability, the number of combinations possible, and the apparent absence of behavioral or mortality influence among such species as the blue-winged teal.

  4. Optimizing the conditions for in vitro maturation and artificial activation of sika deer (Cervus nippon hortulorum) oocytes.

    PubMed

    Yin, Y; Tang, L; Zhang, P; Kong, D; Wang, Z; Guan, J; Song, G; Tang, B; Li, Z

    2013-02-01

    With the goal of establishing experimental protocols for cloning sika deer, various conditions for in vitro maturation (IVM) and artificial activation of sika deer oocytes were examined. In vitro maturation was evaluated in seven different culture media. The highest rate of oocyte maturation was 75.4% in 10 μg/ml follicle-stimulating hormone (FSH), 1 μg/ml LH, 0.2 mm cysteamine and 50 ng/ml epidermal growth factor (EGF) after 24 h of IVM. The efficiency after 24 h of IVM did not differ significantly (p > 0.05) from that observed after 20 h. Cysteamine (0.2 mm) significantly increased the maturation rates after 20 h (from 59.1% to 67.2%, p < 0.05) and after 24 h (from 63.2% to 71.6%, p < 0.05) of IVM. The IVM rates of oocytes collected during the oestrous season (75.4%) and the anoestrous season (23.3%) were significantly different at 24 h. The 20 μg/ml FSH, 2 μg/ml LH, 0.4 mm cysteamine and 100 ng/ml EGF significantly increased the maturation rates (from 23.3% to 54.2%, p < 0.01) at 24 h during the anoestrous season. For the activation experiments, the most effective method was chemical activation [ionomycin + 6-dimethylaminopurine (6-DMAP)], which promoted the development of sika deer oocytes to the blastocyst stage (32.4%). Our results indicate that in vitro matured sika deer oocytes are good candidates for parthenogenetic activation and that chemical treatment is needed for relatively efficient activation of the oocytes. These optimized conditions for IVM and parthenogenetic activation may be useful for efforts to restore populations of the endangered sika deer using the somatic cell nuclear transfer technique. PMID:22458270

  5. An artificial di-iron oxo-protein with phenol oxidase activity

    PubMed Central

    Faiella, Marina; Andreozzi, Concetta; de Rosales, Rafael Torres Martin; Pavone, Vincenzo; Maglio, Ornella; Nastri, Flavia; DeGrado, William F; Lombardi, Angela

    2013-01-01

    Here we report the de novo design and NMR structure of a four-helical bundle di-iron protein with phenol oxidase activity. The introduction of the cofactor-binding and phenol-binding sites required the incorporation of residues that were detrimental to the free energy of folding of the protein. Sufficient stability was, however, obtained by optimizing the sequence of a loop distant from the active site. PMID:19915535

  6. On the convective overstability in protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Latter, Henrik N.

    2016-01-01

    This paper explores the driving of low-level hydrodynamical activity in protoplanetary-disc dead zones. A small adverse radial entropy gradient, ordinarily stabilized by rotation, excites oscillatory convection (`convective overstability') when thermal diffusion, or cooling, is neither too strong nor too weak. I revisit the linear theory of the instability, discuss its prevalence in protoplanetary discs, and show that unstable modes are exact non-linear solutions in the local Boussinesq limit. Overstable modes cannot grow indefinitely, however, as they are subject to a secondary parametric instability that limits their amplitudes to relatively low levels. If parasites set the saturation level of the ensuing turbulence then the convective overstability is probably too weak to drive significant angular momentum transport or to generate vortices. But I also discuss an alternative, and far more vigorous, saturation route that generates radial `layers' or `zonal flows' (witnessed in semiconvection). Numerical simulations are required to determine which outcome is favoured in realistic discs, and consequently how important the instability is for disc dynamics.

  7. Structure-activity relationships in new polycationic molecules based on two 1,4-diazabicyclo[2.2.2]octanes as artificial ribonucleases.

    PubMed

    Burakova, E; Kovalev, N; Zenkova, M; Vlassov, V; Silnikov, V

    2014-12-01

    In the present study, we designed and synthesised new polycationic molecules based on two 1,4-diazabicyclo[2.2.2]octane (DABCO) moieties with hydrophobic groups connected by different linkers. The structure and the RNA-cleavage activity relationships of this novel series of artificial ribonucleases (aRNases) were investigated. PMID:25462988

  8. Natural and artificial radionuclide activity concentrations in surface sediments of Izmit Bay, Turkey.

    PubMed

    Ergül, Halim Aytekin; Belivermiş, Murat; Kılıç, Önder; Topcuoğlu, Sayhan; Çotuk, Yavuz

    2013-12-01

    Surface sediments from the north-eastern coast of the Marmara Sea, Turkey's most industrialized coastal region, were enriched with radioisotopes from the Chernobyl explosion in 1986. Caesium-137 in these sediments is also thought to originate from one former paper mill located nearby that used wood contaminated by Chernobyl explosion-originated (137)Cs for paper production. The average activity concentration of the (137)Cs was 21 Bq kg(-1), while naturally occurring radioisotopes, i.e. (40)K, (226)Ra, and (228)Ra, were 568, 18 and 24 Bq kg(-1), respectively, in surface sediments. The natural radionuclide activities reached their highest levels near petrochemical, phosphate and fertilizer processing facilities. Average (137)Cs activities were generally up to ten times higher than in Middle Eastern marine sediments and lower than those in Northern European sediments. PMID:23981563

  9. Preparation of ormetoprim sulfadimethoxine medicated discs for disc diffusion assay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Romet (a blend of ormetoprim and sulfadimethoxine) is a typeA medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim–sulfadimethoxine susceptibility discs was discontinued. Ormetoprim–sulfadimethoxine discs were prepared at...

  10. Design and Analysis of Hammerhead Ribozyme Activity Against an Artificial Gene Target

    PubMed Central

    Carter, James; Nawtaisong, Pruksa; Balaraman, Velmurugan; Fraser, Malcolm J.

    2014-01-01

    In vitro cleavage assays are routinely conducted to properly assess the catalytic activity of hammerhead ribozymes (HHR) against target RNA molecules like the dengue virus RNA genomes. These experiments are performed for initial assessment of HHR catalysis in a cell-free system and have been simplified by the substitution of agarose gel electrophoresis for SDS-PAGE. Substituting mobility assays enables the analysis of ribozymes in a more rapid fashion without radioisotopes. Here we describe the in vitro transcription of an HHR and corresponding target from T7-promoted plasmids into RNA molecules leading to the analysis of HHR activity against the RNA target by in vitro cleavage assays. PMID:24318886

  11. Three-dimentional simulation of flow-induced platelet activation in artificial heart valves

    NASA Astrophysics Data System (ADS)

    Hedayat, Mohammadali; Asgharzadeh, Hafez; Borazjani, Iman

    2015-11-01

    Since the advent of heart valve, several valve types such as mechanical and bio-prosthetic valves have been designed. Mechanical Heart Valves (MHV) are durable but suffer from thromboembolic complications that caused by shear-induced platelet activation near the valve region. Bio-prosthetic Heart Valves (BHV) are known for better hemodynamics. However, they usually have a short average life time. Realistic simulations of heart valves in combination with platelet activation models can lead to a better understanding of the potential risk of thrombus formation in such devices. In this study, an Eulerian approach is developed to calculate the platelet activation in three-dimensional simulations of flow through MHV and BHV using a parallel overset-curvilinear immersed boundary technique. A curvilinear body-fitted grid is used for the flow simulation through the anatomic aorta, while the sharp-interface immersed boundary method is used for simulation of the Left Ventricle (LV) with prescribed motion. In addition, dynamics of valves were calculated numerically using under-relaxed strong-coupling algorithm. Finally, the platelet activation results for BMV and MHV are compared with each other.

  12. Artificial urushi.

    PubMed

    Kobayashi, S; Uyama, H; Ikeda, R

    2001-11-19

    A new concept for the design and laccase-catalyzed preparation of "artificial urushi" from new urushiol analogues is described. The curing proceeded under mild reaction conditions to produce the very hard cross-linked film (artificial urushi) with a high gloss surface. A new cross-linkable polyphenol was synthesized by oxidative polymerization of cardanol, a phenol derivative from cashew-nut-shell liquid, by enzyme-related catalysts. The polyphenol was readily cured to produce the film (also artificial urushi) showing excellent dynamic viscoelasticity. PMID:11763444

  13. Application of artificial neural networks for the soil moisture retrieval from active and passive microwave spaceborne sensors

    NASA Astrophysics Data System (ADS)

    Santi, Emanuele; Paloscia, Simonetta; Pettinato, Simone; Fontanelli, Giacomo

    2016-06-01

    Among the algorithms used for the retrieval of SMC from microwave sensors (both active, such as Synthetic Aperture Radar-SAR, and passive, radiometers), the artificial neural networks (ANN) represent the best compromise between accuracy and computation speed. ANN based algorithms have been developed at IFAC, and adapted to several radar and radiometric satellite sensors, in order to generate SMC products at a resolution varying from hundreds of meters to tens of kilometers according to the spatial scale of each sensor. These algorithms, which are based on the ANN techniques for inverting theoretical and semi-empirical models, have been adapted to the C- to Ka- band acquisitions from spaceborne radiometers (AMSR-E/AMSR2), SAR (Envisat/ASAR, Cosmo-SkyMed) and real aperture radar (MetOP ASCAT). Large datasets of co-located satellite acquisitions and direct SMC measurements on several test sites worldwide have been used along with simulations derived from forward electromagnetic models for setting up, training and validating these algorithms. An overall quality assessment of the obtained results in terms of accuracy and computational cost was carried out, and the main advantages and limitations for an operational use of these algorithms were evaluated. This technique allowed the retrieval of SMC from both active and passive satellite systems, with accuracy values of about 0.05 m3/m3 of SMC or better, thus making these applications compliant with the usual accuracy requirements for SMC products from space.

  14. Emerging technologies for molecular therapy for intervertebral disc degeneration

    PubMed Central

    Bae, Won C.; Masuda, Koichi

    2014-01-01

    Intervertebral discs are biologically regulated by the maintenance of a balance between the anabolic and catabolic activities of disc cells. Therapeutic agents, initially evaluated using in vitro studies on disc cells and explants, have been used as intradiscal injections in preclinical settings to test in vivo efficacy. These include anabolic growth factors and other biostimulatory agents as well as antagonistic agents against matrix-degrading enzymes and cytokines. Additional work is needed to identify suitable patient populations, using methods such as MRI, and to better understand the mechanism of healing. Clinical trials are currently underway for a few of these agents, while many other promising candidates are on the horizon. PMID:21944594

  15. A Modified Active Appearance Model Based on an Adaptive Artificial Bee Colony

    PubMed Central

    Othman, Zulaiha Ali

    2014-01-01

    Active appearance model (AAM) is one of the most popular model-based approaches that have been extensively used to extract features by highly accurate modeling of human faces under various physical and environmental circumstances. However, in such active appearance model, fitting the model with original image is a challenging task. State of the art shows that optimization method is applicable to resolve this problem. However, another common problem is applying optimization. Hence, in this paper we propose an AAM based face recognition technique, which is capable of resolving the fitting problem of AAM by introducing a new adaptive ABC algorithm. The adaptation increases the efficiency of fitting as against the conventional ABC algorithm. We have used three datasets: CASIA dataset, property 2.5D face dataset, and UBIRIS v1 images dataset in our experiments. The results have revealed that the proposed face recognition technique has performed effectively, in terms of accuracy of face recognition. PMID:25165748

  16. Dual control of spin-electromagnetic wave chaos in active ring oscillators based on artificial multiferroics

    NASA Astrophysics Data System (ADS)

    Kondrashov, A. V.; Ustinov, A. B.; Lähderanta, E.; Pakhomov, O. V.; Nikitin, A. A.; Kalinikos, B. A.

    2015-12-01

    Properties of spin-electromagnetic wave chaos developed in active ring oscillators have been investigated. A multiferroic structure composed of yttrium iron garnet film and barium strontium titanate (BST) slab served as a nonlinear dispersive medium of the oscillator. Dual control of the fractal dimension of the chaotic signal attractor was realized by variation of the ring gain and dielectric permittivity of the BST slab.

  17. Tubulin dynamics during the cytoplasmic cohesiveness cycle in artificially activated sea urchin eggs.

    PubMed

    Coffe, G; Foucault, G; Raymond, M N; Pudles, J

    1983-12-01

    Sedimentation studies and [3H]colchicine-binding assays have demonstrated a relationship between the cytoplasmic cohesiveness cycles and the changes in tubulin organization in Paracentrotus lividus eggs activated by 2.5 mM procaine. The same amount of tubulin (20-25% of the total egg tubulin) is involved in these cyclic process and appears to undergo polymerization and depolymerization cycles. Electron microscopy studies reveal that the microtubules formed during these cytoplasmic cohesiveness cycles are under a particulate form which is sedimentable at low speed. Activation experiments carried out in the presence of cytochalasin B (CB) show that the increase in the cytoplasmic cohesiveness is highly reduced while tubulin polymerization and depolymerization cycles and pronuclear centration are not affected. Although tubulin or actin polymerization can be independently triggered in procaine-activated eggs, the increase in cytoplasmic cohesiveness requires the polymerization of both proteins. However, the cytoplasmic cohesiveness cycles appear to be regulated by tubulin polymerization and depolymerization cycles. PMID:6641809

  18. Inhibition of DNA damage repair by artificial activation of PARP with siDNA.

    PubMed

    Croset, Amelie; Cordelières, Fabrice P; Berthault, Nathalie; Buhler, Cyril; Sun, Jian-Sheng; Quanz, Maria; Dutreix, Marie

    2013-08-01

    One of the major early steps of repair is the recruitment of repair proteins at the damage site, and this is coordinated by a cascade of modifications controlled by phosphatidylinositol 3-kinase-related kinases and/or poly (ADP-ribose) polymerase (PARP). We used short interfering DNA molecules mimicking double-strand breaks (called Dbait) or single-strand breaks (called Pbait) to promote DNA-dependent protein kinase (DNA-PK) and PARP activation. Dbait bound and induced both PARP and DNA-PK activities, whereas Pbait acts only on PARP. Therefore, comparative study of the two molecules allows analysis of the respective roles of the two signaling pathways: both recruit proteins involved in single-strand break repair (PARP, XRCC1 and PCNA) and prevent their recruitment at chromosomal damage. Dbait, but not Pbait, also inhibits recruitment of proteins involved in double-strand break repair (53BP1, NBS1, RAD51 and DNA-PK). By these ways, Pbait and Dbait disorganize DNA repair, thereby sensitizing cells to various treatments. Single-strand breaks repair inhibition depends on direct trapping of the main proteins on both molecules. Double-strand breaks repair inhibition may be indirect, resulting from the phosphorylation of double-strand breaks repair proteins and chromatin targets by activated DNA-PK. The DNA repair inhibition by both molecules is confirmed by their synthetic lethality with BRCA mutations. PMID:23761435

  19. Novel localized heating technique on centrifugal microfluidic disc with wireless temperature monitoring system.

    PubMed

    Joseph, Karunan; Ibrahim, Fatimah; Cho, Jongman

    2015-01-01

    Recent advances in the field of centrifugal microfluidic disc suggest the need for electrical interface in the disc to perform active biomedical assays. In this paper, we have demonstrated an active application powered by the energy harvested from the rotation of the centrifugal microfluidic disc. A novel integration of power harvester disc onto centrifugal microfluidic disc to perform localized heating technique is the main idea of our paper. The power harvester disc utilizing electromagnetic induction mechanism generates electrical energy from the rotation of the disc. This contributes to the heat generation by the embedded heater on the localized heating disc. The main characteristic observed in our experiment is the heating pattern in relative to the rotation of the disc. The heating pattern is monitored wirelessly with a digital temperature sensing system also embedded on the disc. Maximum temperature achieved is 82 °C at rotational speed of 2000 RPM. The technique proves to be effective for continuous heating without the need to stop the centrifugal motion of the disc. PMID:26736977

  20. Evolution of gas in debris discs

    NASA Astrophysics Data System (ADS)

    Kral, Quentin; Wyatt, Mark; Pringle, Jim

    2015-12-01

    A non negligible quantity of gas has been discovered in an increasing number of debris disc systems. ALMA high sensitivity and high resolution is changing our perception of the gaseous component of debris discs as CO is discovered in systems where it should be rapidly photodissociated. It implies that there is a replenishment mechanism and that the observed gas is secondary. Past missions such as Herschel probed the atomic part of the gas through O I and C II emission lines. Gas science in debris discs is still in its infancy, and these new observations raise a handful of questions concerning the mechanisms to create the gas and about its evolution in the planetary system when it is released. The latter question will be addressed in this talk as a self-consistent gas evolution scenario is proposed and is compared to observations for the peculiar case of β Pictoris.Our model proposes that carbon and oxygen within debris discs are created due to photodissociation of CO which is itself created from the debris disc dust (due to grain-grain collisions or photodesorption). The evolution of the carbon atoms is modelled as viscous spreading, with viscosity parameterised using an α model. The temperature, ionisation fraction and population levels of carbon are followed with a PDR model called Cloudy, which is coupled to the dynamical viscous α model. Only carbon gets ionised due to its lower ionisation potential than oxygen. The carbon gas disc can end up with a high ionisation fraction due to strong FUV radiation field. A high ionisation fraction means that the magnetorotational instability (MRI) is very active, so that α is very high. Gas density profiles can be worked out for different input parameters such as the α value, the CO input rate, the location of the input and the incoming radiation field. Observability predictions can be made for future observations, and our model is tested on β Pictoris observations. This new gas evolution model fits the carbon and CO

  1. Fusion activity of influenza virus. A comparison between biological and artificial target membrane vesicles.

    PubMed

    Stegmann, T; Hoekstra, D; Scherphof, G; Wilschut, J

    1986-08-25

    We have investigated the pH-dependent fusion activity of influenza virus toward human erythrocyte ghosts, utilizing a recently developed fluorescence assay, which permits continuous monitoring of the fusion reaction. The rate of fusion is negligible at neutral pH but shows a sharp increase at pH values just below 5.5. This pH dependence profile closely corresponds to that of virus-induced hemolysis. Fusion is rapidly inactivated by a low-pH preincubation of the virus alone either at 37 or at 0 degrees C. The presence of ghosts during this low-pH preincubation, carried out at 0 degree C under which condition there is hardly any fusion, causes a significant protection of the viral fusion activity against inactivation. Fusion initiated at low pH can be arrested instantaneously by readjustment of the pH to neutral. The characteristics of fusion of influenza virus with ghosts deviate from those of fusion with cardiolipin liposomes (Stegmann, T., Hoekstra, D., Scherphof, G., and Wilschut, J. (1985) Biochemistry 24, 3107-3113). Fusion with ghosts is consistent with a requirement of the well-documented pH-dependent conformational change in the viral hemagglutinin, whereas fusion with cardiolipin liposomes does not exhibit a strict dependence on the conformational change. Rather, the negative surface charge on the liposomes plays a critical role, as zwitterionic liposomes containing gangliosides show fusion behavior similar to that of erythrocyte ghosts. PMID:3733744

  2. Central Spindle Self-Organization and Cytokinesis in Artificially Activated Sea Urchin Eggs.

    PubMed

    Henson, John H; Buckley, Mary W; Yeterian, Mesrob; Weeks, Richard M; Simerly, Calvin R; Shuster, Charles B

    2016-04-01

    The ability of microtubules of the mitotic apparatus to control the positioning and initiation of the cleavage furrow during cytokinesis was first established from studies on early echinoderm embryos. However, the identity of the microtubule population that imparts cytokinetic signaling is unclear. The two main--and not necessarily mutually exclusive--candidates are the central spindle and the astral rays. In the present study, we examined cytokinesis in ammonia-activated sea urchin eggs, which lack paternally derived centrosomes and undergo mitosis mediated by unusual anastral, bipolar mini-spindles. Live cell imaging and immunolabeling for microtubules and the centralspindlin constituent and kinesin-related protein, MKLP1, demonstrated that furrowing in ammonia-activated eggs was associated with aligned arrays of centralspindlin-linked, opposed bundles of antiparallel microtubules. These autonomous, zipper-like arrays were not associated with a mitotic apparatus, but did possess characteristics similar to the central spindle region of control, fertilized embryos. Our results highlight the self-organizing nature of the central spindle region and its ability to induce cytokinesis-like furrowing, even in the absence of a complete mitotic apparatus. PMID:27132131

  3. Disc-based microarrays: principles and analytical applications.

    PubMed

    Morais, Sergi; Puchades, Rosa; Maquieira, Ángel

    2016-07-01

    The idea of using disk drives to monitor molecular biorecognition events on regular optical discs has received considerable attention during the last decade. CDs, DVDs, Blu-ray discs and other new optical discs are universal and versatile supports with the potential for development of protein and DNA microarrays. Besides, standard disk drives incorporated in personal computers can be used as compact and affordable optical reading devices. Consequently, a CD technology, resulting from the audio-video industry, has been used to develop analytical applications in health care, environmental monitoring, food safety and quality assurance. The review presents and critically evaluates the current state of the art of disc-based microarrays with illustrative examples, including past, current and future developments. Special mention is made of the analytical developments that use either chemically activated or raw standard CDs where proteins, oligonucleotides, peptides, haptens or other biological probes are immobilized. The discs are also used to perform the assays and must maintain their readability with standard optical drives. The concept and principle of evolving disc-based microarrays and the evolution of disk drives as optical detectors are also described. The review concludes with the most relevant uses ordered chronologically to provide an overview of the progress of CD technology applications in the life sciences. Also, it provides a selection of important references to the current literature. Graphical Abstract High density disc-based microarrays. PMID:26922341

  4. On the vertical-shear instability in astrophysical discs

    NASA Astrophysics Data System (ADS)

    Barker, A. J.; Latter, H. N.

    2015-06-01

    We explore the linear stability of astrophysical discs exhibiting vertical shear, which arises when there is a radial variation in the temperature or entropy. Such discs are subject to a `vertical-shear instability', which recent non-linear simulations have shown to drive hydrodynamic activity in the MRI-stable regions of protoplanetary discs. We first revisit locally isothermal discs using the quasi-global reduced model derived by Nelson et al. This analysis is then extended to global axisymmetric perturbations in a cylindrical domain. We also derive and study a reduced model describing discs with power-law radial entropy profiles (`locally polytropic discs'), which are somewhat more realistic in that they possess physical (as opposed to numerical) surfaces. The fastest growing modes have very short wavelengths and are localized at the disc surfaces (if present), where the vertical shear is maximal. An additional class of modestly growing vertically global body modes is excited, corresponding to destabilized classical inertial waves (`r modes'). We discuss the properties of both types of modes, and stress that those that grow fastest occur on the shortest available length-scales (determined either by the numerical grid or the physical viscous length). This ill-posedness makes simulations of the instability difficult to interpret. We end with some brief speculation on the non-linear saturation and resulting angular momentum transport.

  5. Active vibration control of flexible cantilever plates using piezoelectric materials and artificial neural networks

    NASA Astrophysics Data System (ADS)

    Abdeljaber, Osama; Avci, Onur; Inman, Daniel J.

    2016-02-01

    The study presented in this paper introduces a new intelligent methodology to mitigate the vibration response of flexible cantilever plates. The use of the piezoelectric sensor/actuator pairs for active control of plates is discussed. An intelligent neural network based controller is designed to control the optimal voltage applied on the piezoelectric patches. The control technique utilizes a neurocontroller along with a Kalman Filter to compute the appropriate actuator command. The neurocontroller is trained based on an algorithm that incorporates a set of emulator neural networks which are also trained to predict the future response of the cantilever plate. Then, the neurocontroller is evaluated by comparing the uncontrolled and controlled responses under several types of dynamic excitations. It is observed that the neurocontroller reduced the vibration response of the flexible cantilever plate significantly; the results demonstrated the success and robustness of the neurocontroller independent of the type and distribution of the excitation force.

  6. Selection of a Suitable Disc Bioassay for the Screening of Anti-Tumor Molecules

    PubMed Central

    Trigui, Fatma; Pigeon, Pascal; Jalleli, Karim; Top, Siden; Aifa, Sami; El Arbi, Mehdi

    2013-01-01

    The crown gall induced in potato discs by Agrobacterium tumefaciens is becoming largely utilised in screening anti-tumor agents. The present work is showing that beet discs are more adequate for the anti-tumor screening test. In fact, maximal tumor induction was observed on beet discs (87.5%), followed by carrot discs (75%) and potato discs (68.5%). Beet discs present the most sensibility to crown gall disease with a fast expression of symptoms and more visible galls without any staining need. The beet discs bioassay was carried out by using some synthesized organometallics known for their antitumor activity in mammalian cells. We found significant crown gall inhibition (20.7% to 40.55%) of the tested compounds. Overall results supported that beet bioassay might be a potential prescreen system of anti-tumor molecules in mammalian cells. PMID:24711759

  7. Highly active β-xylosidases of glycoside hydrolase family 43 operating on natural and artificial substrates.

    PubMed

    Jordan, Douglas B; Wagschal, Kurt; Grigorescu, Arabela A; Braker, Jay D

    2013-05-01

    The hemicellulose xylan constitutes a major portion of plant biomass, a renewable feedstock available for conversion to biofuels and other bioproducts. β-xylosidase operates in the deconstruction of the polysaccharide to fermentable sugars. Glycoside hydrolase family 43 is recognized as a source of highly active β-xylosidases, some of which could have practical applications. The biochemical details of four GH43 β-xylosidases (those from Alkaliphilus metalliredigens QYMF, Bacillus pumilus, Bacillus subtilis subsp. subtilis str. 168, and Lactobacillus brevis ATCC 367) are examined here. Sedimentation equilibrium experiments indicate that the quaternary states of three of the enzymes are mixtures of monomers and homodimers (B. pumilus) or mixtures of homodimers and homotetramers (B. subtilis and L. brevis). k cat and k cat/K m values of the four enzymes are higher for xylobiose than for xylotriose, suggesting that the enzyme active sites comprise two subsites, as has been demonstrated by the X-ray structures of other GH43 β-xylosidases. The K i values for D-glucose (83.3-357 mM) and D-xylose (15.6-70.0 mM) of the four enzymes are moderately high. The four enzymes display good temperature (K t (0.5) ∼ 45 °C) and pH stabilities (>4.6 to <10.3). At pH 6.0 and 25 °C, the enzyme from L. brevis ATCC 367 displays the highest reported k cat and k cat/K m on natural substrates xylobiose (407 s(-1), 138 s(-1) mM(-1)), xylotriose (235 s(-1), 80.8 s(-1) mM(-1)), and xylotetraose (146 s(-1), 32.6 s(-1) mM(-1)). PMID:23053115

  8. Artificial selection for high activity favors mighty mini-muscles in house mice.

    PubMed

    Houle-Leroy, Philippe; Guderley, Helga; Swallow, John G; Garland, Theodore

    2003-02-01

    After 14 generations of selection for voluntary wheel running, mice from the four replicate selected lines ran, on average, twice as many revolutions per day as those from the four unselected control lines. To examine whether the selected lines followed distinct strategies in the correlated responses of the size and metabolic capacities of the hindlimb muscles, we examined mice from selected lines, housed for 8 wk in cages with access to running wheels that were either free to rotate ("wheel access" group) or locked ("sedentary"). Thirteen of twenty individuals in one selected line (line 6) and two of twenty in another (line 3) showed a marked reduction ( approximately 50%) in total hindlimb muscle mass, consistent with the previously described expression of a small-muscle phenotype. Individuals with these "mini-muscles" were not significantly smaller in total body mass compared with line-mates with normal-sized muscles. Access to free wheels did not affect the relative mass of the mini-muscles, but did result in typical mammalian training effects for mitochondrial enzyme activities. Individuals with mini-muscles showed a higher mass-specific muscle aerobic capacity as revealed by the maximal in vitro rates of citrate synthase and cytochrome c oxidase. Moreover, these mice showed the highest activities of hexokinase and carnitine palmitoyl transferase. Females with mini-muscles showed the highest levels of phosphofructokinase, and males with mini-muscles the highest levels of pyruvate dehydrogenase. As shown by total muscle enzyme contents, the increase in mass-specific aerobic capacity almost completely compensated for the reduction caused by the "loss" of muscle mass. Moreover, the mini-muscle mice exhibited the lowest contents of lactate dehydrogenase and glycogen phosphorylase. Interestingly, metabolic capacities of mini-muscled mice resemble those of muscles after endurance training. Overall, our results demonstrate that during selection for voluntary wheel

  9. The Influence of Artificially Introduced N-Glycosylation Sites on the In Vitro Activity of Xenopus laevis Erythropoietin

    PubMed Central

    Nagasawa, Kazumichi; Meguro, Mizue; Sato, Kei; Tanizaki, Yuta; Nogawa-Kosaka, Nami; Kato, Takashi

    2015-01-01

    Erythropoietin (EPO), the primary regulator of erythropoiesis, is a heavily glycosylated protein found in humans and several other mammals. Intriguingly, we have previously found that EPO in Xenopus laevis (xlEPO) has no N-glycosylation sites, and cross-reacts with the human EPO (huEPO) receptor despite low homology with huEPO. In this study, we introduced N-glycosylation sites into wild-type xlEPO at the positions homologous to those in huEPO, and tested whether the glycosylated mutein retained its biological activity. Seven xlEPO muteins, containing 1–3 additional N-linked carbohydrates at positions 24, 38, and/or 83, were expressed in COS-1 cells. The muteins exhibited lower secretion efficiency, higher hydrophilicity, and stronger acidic properties than the wild type. All muteins stimulated the proliferation of both cell lines, xlEPO receptor-expressing xlEPOR-FDC/P2 cells and huEPO receptor-expressing UT-7/EPO cells, in a dose-dependent manner. Thus, the muteins retained their in vitro biological activities. The maximum effect on xlEPOR-FDC/P2 proliferation was decreased by the addition of N-linked carbohydrates, but that on UT-7/EPO proliferation was not changed, indicating that the muteins act as partial agonists to the xlEPO receptor, and near-full agonists to the huEPO receptor. Hence, the EPO-EPOR binding site in X. laevis locates the distal region of artificially introduced three N-glycosylation sites, demonstrating that the vital conformation to exert biological activity is conserved between humans and X. laevis, despite the low similarity in primary structures of EPO and EPOR. PMID:25898205

  10. Hemozymes peroxidase activity of artificial hemoproteins constructed from the Streptomyces lividans xylanase A and iron(III)-carboxy-substituted porphyrins.

    PubMed

    Ricoux, Rémy; Dubuc, Roger; Dupont, Claude; Marechal, Jean-Didier; Martin, Aurore; Sellier, Marion; Mahy, Jean-Pierre

    2008-04-01

    To develop artificial hemoproteins that could lead to new selective oxidation biocatalysts, a strategy based on the insertion of various iron-porphyrin cofactors into Xylanase A (Xln10A) was chosen. This protein has a globally positive charge and a wide enough active site to accommodate metalloporphyrins that possess negatively charged substituents such as microperoxidase 8 (MP8), iron(III)-tetra-alpha4-ortho-carboxyphenylporphyrin (Fe(ToCPP)), and iron(III)-tetra-para-carboxyphenylporphyrin (Fe(TpCPP)). Coordination chemistry of the iron atom and molecular modeling studies showed that only Fe(TpCPP) was able to insert deeply into Xln10A, with a KD value of about 0.5 microM. Accordingly, Fe(TpCPP)-Xln10A bound only one imidazole molecule, whereas Fe(TpCPP) free in solution was able to bind two, and the UV-visible spectrum of the Fe(TpCPP)-Xln10A-imidazole complex suggested the binding of an amino acid of the protein on the iron atom, trans to the imidazole. Fe(TpCPP)-Xln10A was found to have peroxidase activity, as it was able to catalyze the oxidation of typical peroxidase cosubstrates such as guaiacol and o-dianisidine by H2O2. With these two cosubstrates, the KM value measured with the Fe(TpCPP)-Xln10A complex was higher than those values observed with free Fe(TpCPP), probably because of the steric hindrance and the increased hydrophobicity caused by the protein around the iron atom of the porphyrin. The peroxidase activity was inhibited by imidazole, and a study of the pH dependence of the oxidation of o-dianisidine suggested that an amino acid with a pKA of around 7.5 was participating in the catalysis. Finally, a very interesting protective effect against oxidative degradation of the porphyrin was provided by the protein. PMID:18324756

  11. Antimicrobial activity of Croton cajucara Benth linalool-rich essential oil on artificial biofilms and planktonic microorganisms.

    PubMed

    Alviano, W S; Mendonça-Filho, R R; Alviano, D S; Bizzo, H R; Souto-Padrón, T; Rodrigues, M L; Bolognese, A M; Alviano, C S; Souza, M M G

    2005-04-01

    We have previously demonstrated that a linalool-rich essential oil from Croton cajucara Benth presents leishmanicidal activity. In the present study, we demonstrate that this essential oil inhibits the growth of reference samples of Candida albicans, Lactobacillus casei, Staphylococcus aureus, Streptococcus sobrinus, Porphyromonas gingivalis and Streptococcus mutans cell suspensions, all of them associated with oral cavity disease. The purified linalool fraction was only inhibitory for C. albicans. Microbes of saliva specimens from human individuals with fixed orthodontic appliances, as well as the reference strains, were used to construct an artificial biofilm which was exposed to linalool or to the essential oil. As in microbial suspensions, the essential oil was toxic for all the microorganisms, while the purified linalool fraction mainly inhibited the growth of C. albicans. The compounds of the essential oil were separated by thin layer chromatography and exposed to the above-cited microorganisms. In this analysis, the proliferation of the bacterial cells was inhibited by still uncharacterized molecules, and linalool was confirmed as the antifungal component of the essential oil. The effects of linalool on the cell biology of C. albicans were evaluated by electron microscopy, which showed that linalool induced a reduction in cell size and abnormal germination. Neither the crude essential oil nor the purified linalool fraction is toxic to mammalian cells, which suggests that the essential oil or its purified components may be useful to control the microbial population in patients with fixed orthodontic appliances. PMID:15720570

  12. Experimental characterization of thermally-activated artificial muscles based on coiled nylon fishing lines

    NASA Astrophysics Data System (ADS)

    Cherubini, Antonello; Moretti, Giacomo; Vertechy, Rocco; Fontana, Marco

    2015-06-01

    The discovery of an innovative class of thermally activated actuators based on twisted polymeric fibres has opened new horizons toward the development of effective devices that can be easily manufactured using inexpensive materials such as fishing lines or sewing threads. These new devices show large deformations when heated together with promising performance in terms of energy and power densities. With the aim of providing information and data useful for the future engineering applications, we present the results of a thermo-mechanical characterization conducted on a specific type of twisted polymeric fibre (i.e. nylon-made coiled actuators) that is considered particularly promising. A custom experimental test-bench and procedure have been developed and employed to run isothermal and isometric tensile tests on a set of specimens that are fabricated with a simple and repeatable process. The results of the experiments highlight some important issues related to the response of these actuators such as hysteresis, repeatability, predictability and stored elastic energy.

  13. Cervical Total Disc Arthroplasty

    PubMed Central

    Basho, Rahul; Hood, Kenneth A.

    2012-01-01

    Symptomatic adjacent segment degeneration of the cervical spine remains problematic for patients and surgeons alike. Despite advances in surgical techniques and instrumentation, the solution remains elusive. Spurred by the success of total joint arthroplasty in hips and knees, surgeons and industry have turned to motion preservation devices in the cervical spine. By preserving motion at the diseased level, the hope is that adjacent segment degeneration can be prevented. Multiple cervical disc arthroplasty devices have come onto the market and completed Food and Drug Administration Investigational Device Exemption trials. Though some of the early results demonstrate equivalency of arthroplasty to fusion, compelling evidence of benefits in terms of symptomatic adjacent segment degeneration are lacking. In addition, non-industry-sponsored studies indicate that these devices are equivalent to fusion in terms of adjacent segment degeneration. Longer-term studies will eventually provide the definitive answer. PMID:24353955

  14. Genetic and Functional Studies of the Intervertebral Disc: A Novel Murine Intervertebral Disc Model

    PubMed Central

    Pelle, Dominic W.; Peacock, Jacqueline D.; Schmidt, Courtney L.; Kampfschulte, Kevin; Scholten, Donald J.; Russo, Scott S.; Easton, Kenneth J.; Steensma, Matthew R.

    2014-01-01

    Intervertebral disc (IVD) homeostasis is mediated through a combination of micro-environmental and biomechanical factors, all of which are subject to genetic influences. The aim of this study is to develop and characterize a genetically tractable, ex vivo organ culture model that can be used to further elucidate mechanisms of intervertebral disc disease. Specifically, we demonstrate that IVD disc explants (1) maintain their native phenotype in prolonged culture, (2) are responsive to exogenous stimuli, and (3) that relevant homeostatic regulatory mechanisms can be modulated through ex-vivo genetic recombination. We present a novel technique for isolation of murine IVD explants with demonstration of explant viability (CMFDA/propidium iodide staining), disc anatomy (H&E), maintenance of extracellular matrix (ECM) (Alcian Blue staining), and native expression profile (qRT-PCR) as well as ex vivo genetic recombination (mT/mG reporter mice; AdCre) following 14 days of culture in DMEM media containing 10% fetal bovine serum, 1% L-glutamine, and 1% penicillin/streptomycin. IVD explants maintained their micro-anatomic integrity, ECM proteoglycan content, viability, and gene expression profile consistent with a homeostatic drive in culture. Treatment of genetically engineered explants with cre-expressing adenovirus efficaciously induced ex vivo genetic recombination in a variety of genetically engineered mouse models. Exogenous administration of IL-1ß and TGF-ß3 resulted in predicted catabolic and anabolic responses, respectively. Genetic recombination of TGFBR1fl/fl explants resulted in constitutively active TGF-ß signaling that matched that of exogenously administered TGF-ß3. Our results illustrate the utility of the murine intervertebral disc explant to investigate mechanisms of intervertebral disc degeneration. PMID:25474689

  15. Double-disc gate valve

    DOEpatents

    Wheatley, Seth J.

    1979-01-01

    This invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewtih, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separtion of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve.

  16. Discs in misaligned binary systems

    NASA Astrophysics Data System (ADS)

    Rawiraswattana, Krisada; Hubber, David A.; Goodwin, Simon P.

    2016-08-01

    We perform SPH simulations to study precession and changes in alignment between the circumprimary disc and the binary orbit in misaligned binary systems. We find that the precession process can be described by the rigid-disc approximation, where the disc is considered as a rigid body interacting with the binary companion only gravitationally. Precession also causes change in alignment between the rotational axis of the disc and the spin axis of the primary star. This type of alignment is of great important for explaining the origin of spin-orbit misaligned planetary systems. However, we find that the rigid-disc approximation fails to describe changes in alignment between the disc and the binary orbit. This is because the alignment process is a consequence of interactions that involve the fluidity of the disc, such as the tidal interaction and the encounter interaction. Furthermore, simulation results show that there are not only alignment processes, which bring the components towards alignment, but also anti-alignment processes, which tend to misalign the components. The alignment process dominates in systems with misalignment angle near 90°, while the anti-alignment process dominates in systems with the misalignment angle near 0° or 180°. This means that highly misaligned systems will become more aligned but slightly misaligned systems will become more misaligned.

  17. Amyloid-β(1-42) protofibrils formed in modified artificial cerebrospinal fluid bind and activate microglia.

    PubMed

    Paranjape, Geeta S; Terrill, Shana E; Gouwens, Lisa K; Ruck, Benjamin M; Nichols, Michael R

    2013-03-01

    Soluble aggregated forms of amyloid-β protein (Aβ) have garnered significant attention recently for their role in Alzheimer's disease (AD). Protofibrils are a subset of these soluble species and are considered intermediates in the aggregation pathway to mature Aβ fibrils. Biological studies have demonstrated that protofibrils exhibit both toxic and inflammatory activities. It is important in these in vitro studies to prepare protofibrils using solution conditions that are appropriate for cellular studies as well as conducive to biophysical characterization of protofibrils. Here we describe the preparation and characterization of Aβ(1-42) protofibrils in modified artificial cerebrospinal fluid (aCSF) and demonstrate their prominent binding and activation of microglial cells. A simple phosphate/bicarbonate buffer system was prepared that maintained the ionic strength and cell compatibility of F-12 medium but did not contain numerous supplements that interfere with spectroscopic analyses of Aβ protofibrils. Reconstitution of Aβ(1-42) in aCSF and isolation with size exclusion chromatography (SEC) revealed curvilinear β-sheet protofibrils <100 nm in length and hydrodynamic radii of 21 nm. Protofibril concentration determination by BCA assay, which was not possible in F-12 medium, was more accurately measured in aCSF. Protofibrils formed and isolated in aCSF, but not monomers, markedly stimulated TNFα production in BV-2 and primary microglia and bound in significant amounts to microglial membranes. This report demonstrates the suitability of a modified aCSF system for preparing SEC-isolated Aβ(1-42) protofibrils and underscores the unique ability of protofibrils to functionally interact with microglia. PMID:23242692

  18. Amyloid-β(1–42) Protofibrils Formed in Modified Artificial Cerebrospinal Fluid Bind and Activate Microglia

    PubMed Central

    Paranjape, Geeta S.; Terrill, Shana E.; Gouwens, Lisa K.; Ruck, Benjamin M.; Nichols, Michael R.

    2012-01-01

    Soluble aggregated forms of amyloid-β protein (Aβ) have garnered significant attention recently for their role in Alzheimer’s disease (AD). Protofibrils are a subset of these soluble species and are considered intermediates in the aggregation pathway to mature Aβ fibrils. Biological studies have demonstrated that protofibrils exhibit both toxic and inflammatory activities. It is important in these in vitro studies to prepare protofibrils using solution conditions that are appropriate for cellular studies as well as conducive to biophysical characterization of protofibrils. Here we describe the preparation and characterization of Aβ(1–42) protofibrils in modified artificial cerebrospinal fluid (aCSF) and demonstrate their prominent binding and activation of microglial cells. A simple phosphate/bicarbonate buffer system was prepared that maintained the ionic strength and cell compatibility of F-12 medium but did not contain numerous supplements that interfere with spectroscopic analyses of Aβ protofibrils. Reconstitution of Aβ(1–42) in aCSF and isolation with size exclusion chromatography (SEC) revealed curvilinear β-sheet protofibrils <100 nm in length and hydrodynamic radii of 21 nm. Protofibril concentration determination by BCA assay, which was not possible in F-12 medium, was more accurately measured in aCSF. Protofibrils formed and isolated in aCSF, but not monomers, markedly stimulated TNFα production in BV-2 and primary microglia and bound in significant amounts to microglial membranes. This report demonstrates the suitability of a modified aCSF system for preparing SEC-isolated Aβ(1–42) protofibrils and underscores the unique ability of protofibrils to functionally interact with microglia. PMID:23242692

  19. Viability, infectivity and fatty acid synthetic activity of Perkinsus marinus meront cells incubated in estuarine and artificial seawater.

    PubMed

    Chu, Fu-Lin E; Lund, Eric D

    2006-07-25

    We investigated the viability and fatty acid synthetic activity of in vitro cultured Perkinsus marinus (Dermo) in lipid-free medium and estuarine water, and the infectivity of P. marinus maintained in artificial seawater (ASW). Viability and fatty acid synthetic activity in 7 d old P. marinus meronts maintained in lipid-free medium and estuarine water were tested. The infectivity of meronts incubated in ASW was examined by first incubating P. marinus meronts in ASW for 2, 3 or 7 d, and then inoculating viable ASW-incubated meronts into the shell cavity of individual oysters Crassostrea virginica. P. marinus infection prevalence and intensity in oysters were determined 9 wk post-inoculation. Heavy mortality occurred in meronts maintained in estuarine water, a drop from an initial value of 100% viable to 7.8 and 6.1% after 3 and 14 d incubation, respectively. Viability was 85 and 67% in meronts maintained in lipid-free medium for 3 and 24 d, respectively. Meronts kept in lipid-free medium for 14 d retained their ability to synthesize fatty acids. Viable meronts incubated in ASW remained infective for up to 7 d. The infection prevalences were 85, 48 and 100%, in the treatments inoculated with viable meronts that were incubated in ASW for 2, 3 and 7 d, respectively. Infection prevalence in the group inoculated with viable meronts immediately after they were transferred to ASW ranged from 61 to 85%. Our results suggest that in nature meronts can survive for at least 14 d outside the host. Viable meronts are not only infective, but are also able to replicate and retain their fatty acid synthetic ability for 7 d. PMID:16956060

  20. Medical Information on Optical Disc*

    PubMed Central

    Schipma, Peter B.; Cichocki, Edward M.; Ziemer, Susan M.

    1987-01-01

    Optical discs may permit a revolutionary change in the distribution and use of medical information. A single compact disc, similar in size to that used for digital audio recording, can contain over 500 million characters of information that is accessible by a Personal Computer. These discs can be manufactured at a cost lower than that of print on paper, at reasonable volumes. Software can provide the health care professional with nearly instantaneous access to the information. Thus, for the first time, the opportunity exists to have large local medical information collections. This paper describes an application of this technology in the field of Oncology.

  1. Artificial Reefs and Ocean Dumping.

    ERIC Educational Resources Information Center

    Glueck, Richard D.

    1983-01-01

    Activities and instructional strategies for two multigrade lessons are provided. Activity objectives include describing an artificial reef (such as a sunken ocean liner) as an ecosystem, knowing animal types in the ecosystem, and describing a food web. (JN)

  2. Artificial noses.

    PubMed

    Stitzel, Shannon E; Aernecke, Matthew J; Walt, David R

    2011-08-15

    The mammalian olfactory system is able to detect many more odorants than the number of receptors it has by utilizing cross-reactive odorant receptors that generate unique response patterns for each odorant. Mimicking the mammalian system, artificial noses combine cross-reactive sensor arrays with pattern recognition algorithms to create robust odor-discrimination systems. The first artificial nose reported in 1982 utilized a tin-oxide sensor array. Since then, however, a wide range of sensor technologies have been developed and commercialized. This review highlights the most commonly employed sensor types in artificial noses: electrical, gravimetric, and optical sensors. The applications of nose systems are also reviewed, covering areas such as food and beverage quality control, chemical warfare agent detection, and medical diagnostics. A brief discussion of future trends for the technology is also provided. PMID:21417721

  3. On total disc replacement.

    PubMed

    Berg, Svante

    2011-02-01

    Low back pain consumes a large part of the community's resources dedicated to health care and sick leave. Back disorders also negatively affect the individual leading to pain suffering, decreased quality-of-life and disability. Chronic low back pain (CLBP) due to degenerative disc disease (DDD) is today often treated with fusion when conservative treatment has failed and symptoms are severe. This treatment is as successful as arthroplasty is for hip arthritis in restoring the patient's quality of life and reducing disability. Even so, there are some problems with this treatment, one of these being recurrent CLBP from an adjacent segment (ASD) after primarily successful surgery. This has led to the development of alternative surgical treatments and devices that maintain or restore mobility, in order to reduce the risk for ASD. Of these new devices, the most frequently used are the disc prostheses used in Total Disc Replacement (TDR). This thesis is based on four studies comparing total disc replacement with posterior fusion. The studies are all based on a material of 152 patients with DDD in one or two segments, aged 20-55 years that were randomly treated with either posterior fusion or TDR. The first study concerned clinical outcome and complications. Follow-up was 100% at both one and two years. It revealed that both treatment groups had a clear benefit from treatment and that patients with TDR were better in almost all outcome scores at one-year follow-up. Fusion patients continued to improve during the second year. At two-year follow-up there was a remaining difference in favour of TDR for back pain. 73% in the TDR group and 63% in the fusion group were much better or totally pain-free (n.s.), while twice as many patients in the TDR group were totally pain free (30%) compared to the fusion group (15%). Time of surgery and total time in hospital were shorter in the TDR group. There was no difference in complications and reoperations, except that seventeen of the

  4. Decellularized allogeneic intervertebral disc: natural biomaterials for regenerating disc degeneration

    PubMed Central

    Hu, Zhijun; Chen, Kai; Shan, Zhi; Chen, Shuai; Wang, Jiying; Mo, Jian; Ma, Jianjun; Xu, Wenbing; Qin, An; Fan, Shunwu

    2016-01-01

    Intervertebral disc degeneration is associated with back pain and disc herniation. This study established a modified protocol for intervertebral disc (IVD) decellularization and prepared its extracellular matrix (ECM). By culturing mesenchymal stem cells (MSCs)(3, 7, 14 and 21 days) and human degenerative IVD cells (7 days) in the ECM, implanting it subcutaneously in rabbit and injecting ECM microparticles into degenerative disc, the biological safety and efficacy of decellularized IVD was evaluated both in vitro and in vivo. Here, we demonstrated that cellular components can be removed completely after decellularization and maximally retain the structure and biomechanics of native IVD. We revealed that allogeneic ECM did not evoke any apparent inflammatory reaction in vivo and no cytotoxicity was found in vitro. Moreover, IVD ECM can induce differentiation of MSCs into IVD-like cells in vitro. Furthermore, allogeneic ECM microparticles are effective on the treatment of rabbit disc degeneration in vivo. In conclusion, our study developed an optimized method for IVD decellularization and we proved decellularized IVD is safe and effective for the treatment of degenerated disc diseases. PMID:26933821

  5. Post-drilling hydrothermal vent and associated biological activities seen through artificial hydrothermal vents in the Iheya North field, Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Takai, K.; Kawagucci, S.; Miyazaki, J.; Watsuji, T.; Ishibashi, J.; Yamamoto, H.; Nozaki, T.; Kashiwabara, T.; Shibuya, T.

    2012-12-01

    In 2010, IODP Expedition 331 was conducted in the Iheya North Field, the Okinawa Trough and drilled several sites in hydrothermally active subseafloor. In addition, during the IODP Expedition 331, four new hydrothermal vents were created. These post-drilling artificial hydrothermal vents provide excellent opportunities to investigate the physical, chemical and microbiological characteristics of the previously unexplored subseafloor hydrothermal fluid reservoirs, and to monitor and estimate how the anthropogenic drilling behaviors affect the deep-sea hydrothermal vent ecosystem. We were very much interested in the difference of hydrothermal fluid chemistry between the natural hydrothermal vents and the artificial hydrothermal vents. The IODP porewater chemistry of the cores pointed to the density-driven stratification of the phase-separated hydrothermal fluids and the natural vent fluids were likely derived only from the shallower vapor-enriched phases. However, the artificial hydrothermal vents had deeper fluid sources in the subseafloor hydrothermal fluid reservoirs composed of vapor-lost (Cl-enriched) phases. The fluids from the artificial hydrothermal vents were sampled by ROV at 5, 12 and 18 months after the IODP expedition. The artificial hydrothermal vent fluids were slightly enriched with Cl as compared to the natural hydrothermal vent fluids. Thus, the artificial hydrothermal vents successfully entrained the previously unexplored subseafloor hydrothermal fluids. The newly created hydrothermal vents also hosted the very quickly grown, enormous chimney structures, of which mineral compositions were highly variable among the vents. However, the quickly grown C0016B and C0016D vent chimneys were found to be typical Kuroko ore even though the chimney growth rates in the artificial vents were extremely faster than those in the natural vents. In addition, the IODP drilling operation not only created new hydrothermal vents by deep drilling but also induced the

  6. Enlivening Physics, a Local Video Disc Project.

    ERIC Educational Resources Information Center

    McInerney, M.

    1989-01-01

    Describes how to make and use an inexpensive video disc of physics demonstrations. Discusses the background, production of the disc, subject of the disc including angular momentum, "monkey and the hunter" experiment, Doppler shift, pressure of a constant volume of gas thermometer, and wave effects, and using the disc in classroom. (YP)

  7. Modeling of rotating disc contactor (RDC) column

    NASA Astrophysics Data System (ADS)

    Ismail, Wan Nurul Aiffah; Zakaria, Siti Aisyah; Noor, Nor Fashihah Mohd; Sulong, Ibrahim; Arshad, Khairil Anuar

    2014-12-01

    Liquid-liquid extraction is one of the most important separation processes. Different kinds of liquid-liquid extractor such as Rotating Disc Contactor (RDC) Column being used in industries. The study of liquid-liquid extraction in an RDC column has become a very important subject to be discussed not just among chemical engineers but mathematician as well. In this research, the modeling of small diameter RDC column using the chemical system involving cumene/isobutryric asid/water are analyzed by the method of Artificial Neural Network (ANN). In the previous research, we begin the process of analyzed the data using methods of design of the experiments (DOE) to identify which factor and their interaction factor are significant and to determine the percentage of contribution of the variance for each factor. From the result obtained, we continue the research by discussed the development and validation of an artificial neural network model in estimating the concentration of continuous and concentration of dispersed outlet for an RDC column. It is expected that an efficient and reliable model will be formed to predict RDC column performance as an alternative to speed up the simulation process.

  8. Reconstitution of biologically active 50S ribosomal subunits with artificial 5S RNA molecules carrying disturbances in the base pairing within the molecular stalk.

    PubMed Central

    Raué, H A; Lorenz, S; Erdmann, V A; Planta, R J

    1981-01-01

    Bacillus stearothermophilus 50S ribosomal subunits were reconstituted in vitro using artificial 5S RNA molecules constructed by combining parts of major and minor type (Raué et al. (1976) Europ. J. Biochem. 68, 169-176) B. licheniformis 5S RNA. The artificial 5S RNA molecules carry defined disturbances (A.C juxtapositions and extra G.U pairs) in the base pairing between the 5'- and 3'-terminal sequences of the molecule (the molecular stalk region). The biological activity of the reconstituted subunits was determined in an E. coli cell-free system programmed with poly-U. The results show that conservation of the base pairing within the molecular stalk is not required for biological activity of 5S RNA. Disturbances of the base pairing within this region do reduce the rate of reconstitution, however. Normal base pairing in the molecular stalk is thus required to ensure efficient ribosome assembly. PMID:6164987

  9. Optimizing stabilization of waste-activated sludge using Fered-Fenton process and artificial neural network modeling (KSOFM, MLP).

    PubMed

    Badalians Gholikandi, Gagik; Masihi, Hamidreza; Azimipour, Mohammad; Abrishami, Ali; Mirabi, Maryam

    2014-01-01

    Sludge management is a fundamental activity in accordance with wastewater treatment aims. Sludge stabilization is always considered as a significant step of wastewater sludge handling. There has been a progressive development observed in the approach to the novel solutions in this regard. In this research, based on own initially experimental results in lab-scale regarding Fered-Fenton processes in view of organic loading (volatile-suspended solids, VSS) removal efficiency, a combination of both methods towards proper improving of excess biological sludge stabilization was investigated. Firstly, VSS removal efficiency has been experimentally studied in lab-scale under different operational conditions taking into consideration pH [Fe(2+)]/[H2O2], detention time [H2O2], and current density parameters. Therefore, the correlations of the same parameters have been determined by utilizing Kohonen self-organizing feature maps (KSOFM). In addition, multi-layer perceptron (MLP) has been employed afterwards for a comprehensive evaluation of investigating parameters correlation and prediction aims. The findings indicated that the best proportion of iron to hydrogen peroxide and the optimum pH were 0.58 and 3.1, respectively. Furthermore, maximum retention time about 6 h with a hydrogen peroxide concentration of 1,568 mg/l and a current density of 650-750 mA results to the optimum VSS removal (efficiency equals to 81 %). The performance of KSOFM and MLP models is found to be magnificent, with correlation ranging (R) from 0.873 to 0.998 for the process simulation and prediction. Finally, it can be concluded that the Fered-Fenton reactor is a suitable efficient process to reduce considerably sludge organic load and mathematical modeling tools as artificial neural networks are impressive methods of process simulation and prediction accordingly. PMID:24562454

  10. Tissue engineering: A live disc

    NASA Astrophysics Data System (ADS)

    Hukins, David W. L.

    2005-12-01

    A material-cell hybrid device that mimics the anatomic shape of the intervertebral disc has been made and successfully implanted into mice to show that tissue engineering may, in the future, benefit sufferers from back pain.

  11. Disc Golf, a Growing Sport

    PubMed Central

    Nelson, Joseph T.; Jones, Richard E.; Runstrom, Michael; Hardy, Jolene

    2015-01-01

    Background Disc golf is a sport played much like traditional golf, but rather than using a ball and club, players throw flying discs with various throwing motions. It has been played by an estimated 8 to 12 million people in the United States. Like all sports, injuries sustained while playing disc golf are not uncommon. Although formalized in the 1970s, it has grown at a rapid pace; however, disc golf–related injuries have yet to be described in the medical literature. Purpose To describe the most common injuries incurred by disc golf players while comparing the different types of throwing styles. Study Design Descriptive epidemiology study. Methods The data in this study were collected from 883 disc golf players who responded to an online survey collected over a 1-month period. Respondents answered 49 questions related to demographics, experience, style of play, and injury details. Using a chi-square analysis, common injuries sustained in players using backhand and forehand throwing styles were compared. Results More than 81% of respondents stated that they had sustained an injury playing disc golf, including injuries to the elbow (n = 325), shoulder (n = 305), back (n = 218), and knee (n = 199). The injuries were most commonly described as a muscle strain (n = 241), sprain (n = 162), and tendinitis (n = 145). The type of throw primarily used by players varied, with 86.2% using backhand, 12.7% using forehand, and 1.1% using an overhead throw. Players using a forehand throw were more likely to sustain an elbow injury (P = .014). Many players (n = 115) stated they had undergone surgery due to a disc golf–related injury, with the most common surgeries including meniscal, shoulder, spine, and foot/ankle surgeries. Conclusion The majority of surveyed disc golfers sustained at least 1 injury while playing disc golf, with many requiring surgery. The types of injuries sustained by players varied by the types of throw primarily used. As the sport of disc golf continues

  12. Percutaneous diode laser disc nucleoplasty

    NASA Astrophysics Data System (ADS)

    Menchetti, P. P.; Longo, Leonardo

    2004-09-01

    The treatment of herniated disc disease (HNP) over the years involved different miniinvasive surgical options. The classical microsurgical approach has been substituted over the years both by endoscopic approach in which is possible to practice via endoscopy a laser thermo-discoplasty, both by percutaneous laser disc nucleoplasty. In the last ten years, the percutaneous laser disc nucleoplasty have been done worldwide in more than 40000 cases of HNP. Because water is the major component of the intervertebral disc, and in HNP pain is caused by the disc protrusion pressing against the nerve root, a 980 nm Diode laser introduced via a 22G needle under X-ray guidance and local anesthesia, vaporizes a small amount of nucleous polposus with a disc shrinkage and a relief of pressure on nerve root. Most patients get off the table pain free and are back to work in 5 to 7 days. Material and method: to date, 130 patients (155 cases) suffering for relevant symptoms therapy-resistant 6 months on average before consulting our department, have been treated. Eightyfour (72%) males and 46 (28%) females had a percutaneous laser disc nucleoplasty. The average age of patients operated was 48 years (22 - 69). The level of disc removal was L3/L4 in 12 cases, L4/L5 in 87 cases and L5/S1 in 56 cases. Two different levels were treated at the same time in 25 patients. Results: the success rate at a minimum follow-up of 6 months was 88% with a complication rate of 0.5%.

  13. Artificial Intelligence.

    ERIC Educational Resources Information Center

    Wash, Darrel Patrick

    1989-01-01

    Making a machine seem intelligent is not easy. As a consequence, demand has been rising for computer professionals skilled in artificial intelligence and is likely to continue to go up. These workers develop expert systems and solve the mysteries of machine vision, natural language processing, and neural networks. (Editor)

  14. Designing mucoadhesive discs containing stem bark extract of Ziziphus jujuba based on Iranian traditional documents

    PubMed Central

    Hamedi, Shokouhsadat; Shams-Ardakani, Mohammad Reza; Sadeghpour, Omid; Amin, Gholamreza; Hajighasemali, Dawood; Orafai, Hossein

    2016-01-01

    Objective (s): Mucoadhesive disc is one of the various routes of drug delivery for curing buccal disease Materials and Methods: Every discs containing 70 mg stem bark extract of Ziziphus jujuba were formulated by using Carbopol 934, PVP k30 and gelatin as polymers. Discs were made by granulation and direct compression. Discs were standardized based on the total phenol. Properties such as in vitro and in vivo mucoadhesion, drug release, water uptake, and disintegration were carried out. Results: Discs showed excellent mucoadhesion and released high amount of the active ingredients (47%) immediately and completed after approximately the first hour. They had a good adhesion in buccal cavity. Conclusion: This study showed that the kinetics of release of the active substance from the mucoadhesive disc obeyed the zero order kinetic and didn’t follow the fick's law. The water uptake and dissolution (DS), increased with the passing of time. PMID:27114804

  15. Disc piezoelectric ceramic transformers.

    PubMed

    Erhart, Jirií; Půlpán, Petr; Doleček, Roman; Psota, Pavel; Lédl, Vít

    2013-08-01

    In this contribution, we present our study on disc-shaped and homogeneously poled piezoelectric ceramic transformers working in planar-extensional vibration modes. Transformers are designed with electrodes divided into wedge, axisymmetrical ring-dot, moonie, smile, or yin-yang segments. Transformation ratio, efficiency, and input and output impedances were measured for low-power signals. Transformer efficiency and transformation ratio were measured as a function of frequency and impedance load in the secondary circuit. Optimum impedance for the maximum efficiency has been found. Maximum efficiency and no-load transformation ratio can reach almost 100% and 52 for the fundamental resonance of ring-dot transformers and 98% and 67 for the second resonance of 2-segment wedge transformers. Maximum efficiency was reached at optimum impedance, which is in the range from 500 Ω to 10 kΩ, depending on the electrode pattern and size. Fundamental vibration mode and its overtones were further studied using frequency-modulated digital holographic interferometry and by the finite element method. Complementary information has been obtained by the infrared camera visualization of surface temperature profiles at higher driving power. PMID:25004532

  16. Estimating the fossil disc mass during supermassive black hole mergers: the importance of torque implementation

    NASA Astrophysics Data System (ADS)

    Tazzari, M.; Lodato, G.

    2015-05-01

    In this paper, we revisit the issue of estimating the `fossil' disc mass in the circumprimary disc, during the merger of a supermassive black hole binary. As the binary orbital decay speeds up due to the emission of gravitational waves, the gas in the circumprimary disc might be forced to accrete rapidly and could in principle provide a significant electromagnetic counterpart to the gravitational wave emission. Since the luminosity of such flare is proportional to the gaseous mass in the circumprimary disc, estimating such mass accurately is important. Previous investigations of this issue have produced contradictory results, with some authors estimating super-Eddington flares and large disc mass, while others suggesting that the `fossil' disc mass is very low, even less than a Jupiter mass. Here, we perform simple 1D calculations to show that such very low estimates of the disc mass are an artefact of the specific implementation of the tidal torque in 1D models. In particular, for moderate mass ratios of the binary, the usual formula for the torque used in 1D models significantly overestimates the width of the gap induced by the secondary and this artificially leads to a very small leftover circumprimary disc. Using a modified torque, calibrated to reproduce the correct gap width as estimated by 3D models, leads to fossil disc masses of the order of one solar mass. The rapid accretion of the whole circumprimary disc would produce peak luminosities of the order of 1-20 times the Eddington luminosity. Even if a significant fraction of the gas escapes accretion by flowing out the secondary orbit during the merger (an effect not included in our calculations), we would still predict close to Eddington luminosities that might be easily detected.

  17. Testing hydrodynamics schemes in galaxy disc simulations

    NASA Astrophysics Data System (ADS)

    Few, C. G.; Dobbs, C.; Pettitt, A.; Konstandin, L.

    2016-08-01

    We examine how three fundamentally different numerical hydrodynamics codes follow the evolution of an isothermal galactic disc with an external spiral potential. We compare an adaptive mesh refinement code (RAMSES), a smoothed particle hydrodynamics code (SPHNG), and a volume-discretized mesh-less code (GIZMO). Using standard refinement criteria, we find that RAMSES produces a disc that is less vertically concentrated and does not reach such high densities as the SPHNG or GIZMO runs. The gas surface density in the spiral arms increases at a lower rate for the RAMSES simulations compared to the other codes. There is also a greater degree of substructure in the SPHNG and GIZMO runs and secondary spiral arms are more pronounced. By resolving the Jeans length with a greater number of grid cells, we achieve more similar results to the Lagrangian codes used in this study. Other alterations to the refinement scheme (adding extra levels of refinement and refining based on local density gradients) are less successful in reducing the disparity between RAMSES and SPHNG/GIZMO. Although more similar, SPHNG displays different density distributions and vertical mass profiles to all modes of GIZMO (including the smoothed particle hydrodynamics version). This suggests differences also arise which are not intrinsic to the particular method but rather due to its implementation. The discrepancies between codes (in particular, the densities reached in the spiral arms) could potentially result in differences in the locations and time-scales for gravitational collapse, and therefore impact star formation activity in more complex galaxy disc simulations.

  18. Simulation of biological therapies for degenerated intervertebral discs.

    PubMed

    Zhu, Qiaoqiao; Gao, Xin; Temple, H Thomas; Brown, Mark D; Gu, Weiyong

    2016-04-01

    The efficacy of biological therapies on intervertebral disc repair was quantitatively studied using a three-dimensional finite element model based on a cell-activity coupled multiphasic mixture theory. In this model, cell metabolism and matrix synthesis and degradation were considered. Three types of biological therapies-increasing the cell density (Case I), increasing the glycosaminoglycan (GAG) synthesis rate (Case II), and decreasing the GAG degradation rate (Case III)-to the nucleus pulposus (NP) of each of two degenerated discs [one mildly degenerated (e.g., 80% viable cells in the NP) and one severely degenerated (e.g., 30% viable cells in the NP)] were simulated. Degenerated discs without treatment were also simulated as a control. The cell number needed, nutrition level demanded, time required for the repair, and the long-term outcomes of these therapies were analyzed. For Case I, the repair process was predicted to be dependent on the cell density implanted and the nutrition level at disc boundaries. With sufficient nutrition supply, this method was predicted to be effective for treating both mildly and severely degenerated discs. For Case II, the therapy was predicted to be effective for repairing the mildly degenerated disc, but not for the severely degenerated disc. Similar results were predicted for Case III. No change in cell density for Cases II and III were predicted under normal nutrition level. This study provides a quantitative guide for choosing proper strategies of biological therapies for different degenerated discs. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:699-708, 2016. PMID:26425965

  19. MRI Evaluation of Lumbar Disc Degenerative Disease

    PubMed Central

    Patel, Rupal; Mehta, Chetan; Patel, Narrotam

    2015-01-01

    Introduction: Lower back pain secondary to degenerative disc disease is a condition that affects young to middle-aged persons with peak incidence at approximately 40 y. MRI is the standard imaging modality for detecting disc pathology due to its advantage of lack of radiation, multiplanar imaging capability, excellent spinal soft-tissue contrast and precise localization of intervertebral discs changes. Aims and Objective: To evaluate the characterization, extent, and changes associated with the degenerative lumbar disc disease by Magnetic Resonance Imaging. Study Design: Cross-sectional and observational study. Materials and Methods: A total 109 patients of the lumbar disc degeneration with age group between 17 to 80 y were diagnosed & studied on 1.5 Tesla Magnetic Resonance Imaging machine. MRI findings like lumbar lordosis, Schmorl’s nodes, decreased disc height, disc annular tear, disc herniation, disc bulge, disc protrusion and disc extrusion were observed. Narrowing of the spinal canal, lateral recess and neural foramen with compression of nerve roots observed. Ligamentum flavum thickening and facetal arthropathy was observed. Result: Males were more commonly affected in Degenerative Spinal Disease & most of the patients show loss of lumbar lordosis. Decreased disc height was common at L5-S1 level. More than one disc involvement was seen per person. L4 – L5 disc was the most commonly involved. Annular disc tear, disc herniation, disc extrusion, narrowing of spinal canal, narrowing of lateral recess, compression of neural foramen, ligamentum flavum thickening and facetal arthropathy was common at the L4 –L5 disc level. Disc buldge was common at L3 – L4 & L4 – L5 disc level. Posterior osteophytes are common at L3 - L4 & L5 –S1 disc level. L1- L2 disc involvement and spondylolisthesis are less common. Conclusion: Lumbar disc degeneration is the most common cause of low back pain. Plain radiograph can be helpful in visualizing gross anatomic changes in

  20. Nuclear DISC1 regulates CRE-mediated gene transcription and sleep homeostasis in the fruit fly.

    PubMed

    Sawamura, N; Ando, T; Maruyama, Y; Fujimuro, M; Mochizuki, H; Honjo, K; Shimoda, M; Toda, H; Sawamura-Yamamoto, T; Makuch, L A; Hayashi, A; Ishizuka, K; Cascella, N G; Kamiya, A; Ishida, N; Tomoda, T; Hai, T; Furukubo-Tokunaga, K; Sawa, A

    2008-12-01

    Disrupted-in-schizophrenia-1 (DISC1) is one of major susceptibility factors for a wide range of mental illnesses, including schizophrenia, bipolar disorder, major depression and autism spectrum conditions. DISC1 is located in several subcellular domains, such as the centrosome and the nucleus, and interacts with various proteins, including NudE-like (NUDEL/NDEL1) and activating transcription factor 4 (ATF4)/CREB2. Nevertheless, a role for DISC1 in vivo remains to be elucidated. Therefore, we have generated a Drosophila model for examining normal functions of DISC1 in living organisms. DISC1 transgenic flies with preferential accumulation of exogenous human DISC1 in the nucleus display disturbance in sleep homeostasis, which has been reportedly associated with CREB signaling/CRE-mediated gene transcription. Thus, in mammalian cells, we characterized nuclear DISC1, and identified a subset of nuclear DISC1 that colocalizes with the promyelocytic leukemia (PML) bodies, a nuclear compartment for gene transcription. Furthermore, we identified three functional cis-elements that regulate the nuclear localization of DISC1. We also report that DISC1 interacts with ATF4/CREB2 and a corepressor N-CoR, modulating CRE-mediated gene transcription. PMID:18762802

  1. Inhomogeneous accretion discs and the soft states of black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Dexter, Jason; Quataert, Eliot

    2012-10-01

    Observations of black hole binaries (BHBs) have established a rich phenomenology of X-ray states. The soft states range from the low variability, accretion disc dominated thermal (TD) state to the higher variability, non-thermal steep power law (SPL) state. The disc component in all states is typically modelled with standard thin disc accretion theory. However, this theory is inconsistent with optical/UV spectral, variability and gravitational microlensing observations of active galactic nuclei (AGNs), the supermassive analogues of BHBs. An inhomogeneous disc (ID) model with large (≃0.4 dex) temperature fluctuations in each radial annulus can qualitatively explain all of these AGN observations. The inhomogeneity may be a consequence of instabilities in radiation-dominated discs, and therefore may be present in BHBs as well. We show that ID models can explain many features of the TD and SPL states of BHBs. The observed relationships between spectral hardness, disc fraction and rms variability amplitude in BHBs are reproduced with temperature fluctuations similar to those inferred in AGNs, suggesting a unified picture of luminous accretion discs across orders of magnitude in black hole mass. This picture can be tested with spectral fitting of ID models, X-ray polarization observations and radiation magnetohydrodynamic simulations. If BHB accretion discs are indeed inhomogeneous, only the most disc-dominated states (disc fraction ≳0.95) can be used to robustly infer black hole spin using current continuum fitting methods.

  2. An artificial molecular pump.

    PubMed

    Cheng, Chuyang; McGonigal, Paul R; Schneebeli, Severin T; Li, Hao; Vermeulen, Nicolaas A; Ke, Chenfeng; Stoddart, J Fraser

    2015-06-01

    Carrier proteins consume fuel in order to pump ions or molecules across cell membranes, creating concentration gradients. Their control over diffusion pathways, effected entirely through noncovalent bonding interactions, has inspired chemists to devise artificial systems that mimic their function. Here, we report a wholly artificial compound that acts on small molecules to create a gradient in their local concentration. It does so by using redox energy and precisely organized noncovalent bonding interactions to pump positively charged rings from solution and ensnare them around an oligomethylene chain, as part of a kinetically trapped entanglement. A redox-active viologen unit at the heart of a dumbbell-shaped molecular pump plays a dual role, first attracting and then repelling the rings during redox cycling, thereby enacting a flashing energy ratchet mechanism with a minimalistic design. Our artificial molecular pump performs work repetitively for two cycles of operation and drives rings away from equilibrium toward a higher local concentration. PMID:25984834

  3. An artificial molecular pump

    NASA Astrophysics Data System (ADS)

    Cheng, Chuyang; McGonigal, Paul R.; Schneebeli, Severin T.; Li, Hao; Vermeulen, Nicolaas A.; Ke, Chenfeng; Stoddart, J. Fraser

    2015-06-01

    Carrier proteins consume fuel in order to pump ions or molecules across cell membranes, creating concentration gradients. Their control over diffusion pathways, effected entirely through noncovalent bonding interactions, has inspired chemists to devise artificial systems that mimic their function. Here, we report a wholly artificial compound that acts on small molecules to create a gradient in their local concentration. It does so by using redox energy and precisely organized noncovalent bonding interactions to pump positively charged rings from solution and ensnare them around an oligomethylene chain, as part of a kinetically trapped entanglement. A redox-active viologen unit at the heart of a dumbbell-shaped molecular pump plays a dual role, first attracting and then repelling the rings during redox cycling, thereby enacting a flashing energy ratchet mechanism with a minimalistic design. Our artificial molecular pump performs work repetitively for two cycles of operation and drives rings away from equilibrium toward a higher local concentration.

  4. Artificial Intelligence.

    PubMed

    Lawrence, David R; Palacios-González, César; Harris, John

    2016-04-01

    It seems natural to think that the same prudential and ethical reasons for mutual respect and tolerance that one has vis-à-vis other human persons would hold toward newly encountered paradigmatic but nonhuman biological persons. One also tends to think that they would have similar reasons for treating we humans as creatures that count morally in our own right. This line of thought transcends biological boundaries-namely, with regard to artificially (super)intelligent persons-but is this a safe assumption? The issue concerns ultimate moral significance: the significance possessed by human persons, persons from other planets, and hypothetical nonorganic persons in the form of artificial intelligence (AI). This article investigates why our possible relations to AI persons could be more complicated than they first might appear, given that they might possess a radically different nature to us, to the point that civilized or peaceful coexistence in a determinate geographical space could be impossible to achieve. PMID:26957450

  5. Quantitative structure–activity relationship study of P2X7 receptor inhibitors using combination of principal component analysis and artificial intelligence methods

    PubMed Central

    Ahmadi, Mehdi; Shahlaei, Mohsen

    2015-01-01

    P2X7 antagonist activity for a set of 49 molecules of the P2X7 receptor antagonists, derivatives of purine, was modeled with the aid of chemometric and artificial intelligence techniques. The activity of these compounds was estimated by means of combination of principal component analysis (PCA), as a well-known data reduction method, genetic algorithm (GA), as a variable selection technique, and artificial neural network (ANN), as a non-linear modeling method. First, a linear regression, combined with PCA, (principal component regression) was operated to model the structure–activity relationships, and afterwards a combination of PCA and ANN algorithm was employed to accurately predict the biological activity of the P2X7 antagonist. PCA preserves as much of the information as possible contained in the original data set. Seven most important PC's to the studied activity were selected as the inputs of ANN box by an efficient variable selection method, GA. The best computational neural network model was a fully-connected, feed-forward model with 7−7−1 architecture. The developed ANN model was fully evaluated by different validation techniques, including internal and external validation, and chemical applicability domain. All validations showed that the constructed quantitative structure–activity relationship model suggested is robust and satisfactory. PMID:26600858

  6. Quantitative structure-activity relationship study of P2X7 receptor inhibitors using combination of principal component analysis and artificial intelligence methods.

    PubMed

    Ahmadi, Mehdi; Shahlaei, Mohsen

    2015-01-01

    P2X7 antagonist activity for a set of 49 molecules of the P2X7 receptor antagonists, derivatives of purine, was modeled with the aid of chemometric and artificial intelligence techniques. The activity of these compounds was estimated by means of combination of principal component analysis (PCA), as a well-known data reduction method, genetic algorithm (GA), as a variable selection technique, and artificial neural network (ANN), as a non-linear modeling method. First, a linear regression, combined with PCA, (principal component regression) was operated to model the structure-activity relationships, and afterwards a combination of PCA and ANN algorithm was employed to accurately predict the biological activity of the P2X7 antagonist. PCA preserves as much of the information as possible contained in the original data set. Seven most important PC's to the studied activity were selected as the inputs of ANN box by an efficient variable selection method, GA. The best computational neural network model was a fully-connected, feed-forward model with 7-7-1 architecture. The developed ANN model was fully evaluated by different validation techniques, including internal and external validation, and chemical applicability domain. All validations showed that the constructed quantitative structure-activity relationship model suggested is robust and satisfactory. PMID:26600858

  7. Interlaced dynamics of density waves and vortices in self-gravitating Discs

    NASA Astrophysics Data System (ADS)

    Mamatsashvili, G. R.

    2013-04-01

    Latest developments in the dynamics of density waves and vortices in selfgravitating protoplanetary discs is reviewed. It is well established by now that in discs, vortices are dynamically coupled with density waves due to the disc's differential rotation, or shear. On the other hand, density waves play a central role in the theory of self-gravitating discs and recently revealed their coupling with vortices implies that the latter can also be subject to self-gravity effects, thus taking active part in defining overall dynamics of self-gravitating discs. We describe the specific features of vortex dynamics and evolution in self-gravitating discs with and without driving by baroclinic or Rossby wave instabilities and point out differences between these two case.

  8. Automatic diagnosis of lumbar disc herniation with shape and appearance features from MRI

    NASA Astrophysics Data System (ADS)

    Alomari, Raja'S.; Corso, Jason J.; Chaudhary, Vipin; Dhillon, Gurmeet

    2010-03-01

    Intervertebral disc herniation is a major reason for lower back pain (LBP), which is the second most common neurological ailment in the United States. Automation of herniated disc diagnosis reduces the large burden on radiologists who have to diagnose hundreds of cases each day using clinical MRI. We present a method for automatic diagnosis of lumbar disc herniation using appearance and shape features. We jointly use the intensity signal for modeling the appearance of herniated disc and the active shape model for modeling the shape of herniated disc. We utilize a Gibbs distribution for classification of discs using appearance and shape features. We use 33 clinical MRI cases of the lumbar area for training and testing both appearance and shape models. We achieve over 91% accuracy in detection of herniation in a cross-validation experiment with specificity of 91% and sensitivity of 94%.

  9. Chondrule transport in protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Goldberg, Aaron Z.; Owen, James E.; Jacquet, Emmanuel

    2015-10-01

    Chondrule formation remains one of the most elusive early Solar system events. Here, we take the novel approach of employing numerical simulations to investigate chondrule origin beyond purely cosmochemical methods. We model the transport of generically produced chondrules and dust in a 1D viscous protoplanetary disc model in order to constrain the chondrule formation events. For a single formation event we are able to match analytical predictions of the memory they retain of each other (complementarity), finding that a large mass accretion rate (≳10-7 M⊙ yr-1) allows for delays on the order of the disc's viscous time-scale between chondrule formation and chondrite accretion. Further, we find older discs to be severely diminished of chondrules, with accretion rates ≲10-9 M⊙ yr-1 for nominal parameters. We then characterize the distribution of chondrule origins in both space and time, as functions of disc parameters and chondrule formation rates, in runs with continuous chondrule formation and both static and evolving discs. Our data suggest that these can account for the observed diversity between distinct chondrite classes, if some diversity in accretion time is allowed for.

  10. Gravitoturbulence in magnetized protostellar discs

    NASA Astrophysics Data System (ADS)

    Riols, A.; Latter, H.

    2016-08-01

    Gravitational instability (GI) features in several aspects of protostellar disc evolution, most notably in angular momentum transport, fragmentation, and the outbursts exemplified by FU Ori and EX Lupi systems. The outer regions of protostellar discs may also be coupled to magnetic fields, which could then modify the development of GI. To understand the basic elements of their interaction, we perform local 2D ideal and resistive magnetohydrodynamics simulations with an imposed toroidal field. In the regime of moderate plasma beta, we find that the system supports a hot gravitoturbulent state, characterized by considerable magnetic energy and stress and a surprisingly large Toomre parameter Q ≳ 10. This result has potential implications for disc structure, vertical thickness, ionization, etc. Our simulations also reveal the existence of long-lived and dense `magnetic islands' or plasmoids. Lastly, we find that the presence of a magnetic field has little impact on the fragmentation criterion of the disc. Though our focus is on protostellar discs, some of our results may be relevant for the outer radii of AGN.

  11. Competitive coordination aggregation for V-shaped [Co3] and disc-like [Co7] complexes: synthesis, magnetic properties and catechol oxidase activity.

    PubMed

    Singha Mahapatra, Tufan; Basak, Dipmalya; Chand, Santanu; Lengyel, Jeff; Shatruk, Michael; Bertolasi, Valerio; Ray, Debashis

    2016-09-14

    Unique dependence on the nature of metal salt and reaction conditions for coordination assembly reactions of varying architecture and nuclearity have been identified in V-shaped [Co3L4] and planar disc-like [Co7L6] compounds: [CoL2(μ-L)2(μ-OH2)2(CF3CO2)2] (1) and [Co(μ-L)6(μ-OMe)6]Cl2 (2) (HL = 2-{(3-ethoxypropylimino)methyl}-6-methoxyphenol). At room temperature varying reaction conditions, cobalt-ligand ratios and use of different bases allowed unique types of coordination self-assembly. The synthetic marvel lies in the nature of aggregation with respect to the two unrelated cores in 1 and 2. Complex 1 assumes a V-shaped arrangement bound to L(-), water and a trifluoroacetate anion, while 2 grows around a central Co(II) ion surrounded by a {Co} hexagon bound to methoxide and L(-). Magnetic measurements revealed that the intermetallic interactions are antiferromagnetic in nature in the case of complex 1 and ferromagnetic in the case of 2 involving high spin cobalt(ii) ions with stabilization of the high-spin ground state in the latter case. In MeCN solutions complexes 1 and 2 showed catalytic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBCH2) to 3,5-di-tert-butylbenzoquinone (3,5-DTBQ) in air. The kinetic study in MeCN revealed that with respect to the catalytic turnover number (kcat) 2 is more effective than 1 for oxidation of 3,5-DTBCH2. PMID:27510847

  12. Black hole accretion disc impacts

    NASA Astrophysics Data System (ADS)

    Pihajoki, P.

    2016-04-01

    We present an analytic model for computing the luminosity and spectral evolution of flares caused by a supermassive black hole impacting the accretion disc of another supermassive black hole. Our model includes photon diffusion, emission from optically thin regions and relativistic corrections to the observed spectrum and time-scales. We test the observability of the impact scenario with a simulated population of quasars hosting supermassive black hole binaries. The results indicate that for a moderate binary mass ratio of 0.3, and impact distances of 100 primary Schwarzschild radii, the accretion disc impacts can be expected to equal or exceed the host quasar in brightness at observed wavelength λ = 510 nm up to z = 0.6. We conclude that accretion disc impacts may function as an independent probe for supermassive black hole binaries. We release the code used for computing the model light curves to the community.

  13. Laser engineering of spine discs

    NASA Astrophysics Data System (ADS)

    Sobol, E.; Zakharkina, O.; Baskov, A.; Shekhter, A.; Borschenko, I.; Guller, A.; Baskov, V.; Omelchenko, A.; Sviridov, A.

    2009-04-01

    The laser engineering of intervertebral discs is one of the branch of medical physics aimed at the development of minimally invasive laser medical techniques based on the effect of the controlled (time- and space-modulated) laser radiation on the structure and the field of mechanical stress of biological tissues. A new method for the laser engineering of the intervertebral discs and the differences of this approach from the existing physical methods of medical treatment are considered. The newly formed tissues of animals and humans are hystologically studied. Possible regeneration processes are discussed. A control system that provides for the treatment efficiency and safety is developed. The new laser medical equipment that is designed for the laser engineering of intervertebral discs is described, and the corresponding results of the clinical application are presented.

  14. Debris disc formation induced by planetary growth

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Löhne, T.

    2014-08-01

    Several hundred stars older than 10 million years have been observed to have infrared excesses. These observations are explained by dust grains formed by the collisional fragmentation of hidden planetesimals. Such dusty planetesimal discs are known as debris discs. In a dynamically cold planetesimal disc, collisional coagulation of planetesimals produces planetary embryos which then stir the surrounding leftover planetesimals. Thus, the collisional fragmentation of planetesimals that results from planet formation forms a debris disc. We aim to determine the properties of the underlying planetesimals in debris discs by numerically modelling the coagulation and fragmentation of planetesimal populations. The brightness and temporal evolution of debris discs depend on the radial distribution of planetesimal discs, the location of their inner and outer edges, their total mass, and the size of planetesimals in the disc. We find that a radially narrow planetesimal disc is most likely to result in a debris disc that can explain the trend of observed infrared excesses of debris discsvvv around G-type stars, for which planet formation occurs only before 100 million years. Early debris disc formation is induced by planet formation, while the later evolution is explained by the collisional decay of leftover planetesimals around planets that have already formed. Planetesimal discs with underlying planetesimals of radii ˜100 km at ≈30 au most readily explain the Spitzer Space Telescope 24 and 70 μm fluxes from debris discs around G-type stars.

  15. DISC1–ATF4 transcriptional repression complex: dual regulation of the cAMP-PDE4 cascade by DISC1

    PubMed Central

    Soda, T; Frank, C; Ishizuka, K; Baccarella, A; Park, Y-U; Flood, Z; Park, S K; Sawa, A; Tsai, L-H

    2013-01-01

    Disrupted-In-Schizophrenia 1 (DISC1), a risk factor for major mental illnesses, has been studied extensively in the context of neurodevelopment. However, the role of DISC1 in neuronal signaling, particularly in conjunction with intracellular cascades that occur in response to dopamine, a neurotransmitter implicated in numerous psychiatric disorders, remains elusive. Previous data suggest that DISC1 interacts with numerous proteins that impact neuronal function, including activating transcription factor 4 (ATF4). In this study, we identify a novel DISC1 and ATF4 binding region in the genomic locus of phosphodiesterase 4D (PDE4D), a gene implicated in psychiatric disorders. We found that the loss of function of either DISC1 or ATF4 increases PDE4D9 transcription, and that the association of DISC1 with the PDE4D9 locus requires ATF4. We also show that PDE4D9 is increased by D1-type dopamine receptor dopaminergic stimulation. We demonstrate that the mechanism for this increase is due to DISC1 dissociation from the PDE4D locus in mouse brain. We further characterize the interaction of DISC1 with ATF4 to show that it is regulated via protein kinase A-mediated phosphorylation of DISC1 serine-58. Our results suggest that the release of DISC1-mediated transcriptional repression of PDE4D9 acts as feedback inhibition to regulate dopaminergic signaling. Furthermore, as DISC1 loss-of-function leads to a specific increase in PDE4D9, PDE4D9 itself may represent an attractive target for therapeutic approaches in psychiatric disorders. PMID:23587879

  16. Artificial halos

    NASA Astrophysics Data System (ADS)

    Selmke, Markus

    2015-09-01

    Judged by their frequency and beauty, ice halos easily rival rainbows as a prominent atmospheric optics phenomenon. This article presents experimental halo demonstrations of varying complexity. Using a single commercially available hexagonal glass prism, a variety of artificial halos can be simulated. The experiments include laser beam path analysis, a modified classic spinning prism experiment, and a novel Monte-Carlo machine for three-dimensional rotations. Each of these experiments emulates different conditions of certain halo displays, and in combination, they allow a thorough understanding of these striking phenomena.

  17. Design, RNA cleavage and antiviral activity of new artificial ribonucleases derived from mono-, di- and tripeptides connected by linkers of different hydrophobicity.

    PubMed

    Tamkovich, Nikolay; Koroleva, Lyudmila; Kovpak, Mikhail; Goncharova, Elena; Silnikov, Vladimir; Vlassov, Valentin; Zenkova, Marina

    2016-03-15

    A novel series of metal-free artificial ribonucleases (aRNases) was designed, synthesized and assessed in terms of ribonuclease activity and ability to inactivate influenza virus WSN/A33/H1N1 in vitro. The compounds were built of two short peptide fragments, which include Lys, Ser, Arg, Glu and imidazole residues in various combinations, connected by linkers of different hydrophobicity (1,12-diaminododecane or 4,9-dioxa-1,12-diaminododecane). These compounds efficiently cleaved different RNA substrates under physiological conditions at rates three to five times higher than that of artificial ribonucleases described earlier and displayed RNase A-like cleavage specificity. aRNases with the hydrophobic 1,12-diaminododecane linker displayed ribonuclease activity 3-40 times higher than aRNases with the 4,9-dioxa-1,12-diaminododecane linker. The assumed mechanism of RNA cleavage was typical for natural ribonucleases, that is, general acid-base catalysis via the formation of acid/base pairs by functional groups of amino acids present in the aRNases; the pH profile of cleavage confirmed this mechanism. The most active aRNases under study exhibited high antiviral activity and entirely inactivated influenza virus A/WSN/33/(H1N1) after a short incubation period of viral suspension under physiological conditions. PMID:26899594

  18. Artificial Induction of Associative Olfactory Memory by Optogenetic and Thermogenetic Activation of Olfactory Sensory Neurons and Octopaminergic Neurons in Drosophila Larvae

    PubMed Central

    Honda, Takato; Lee, Chi-Yu; Honjo, Ken; Furukubo-Tokunaga, Katsuo

    2016-01-01

    The larval brain of Drosophila melanogaster provides an excellent system for the study of the neurocircuitry mechanism of memory. Recent development of neurogenetic techniques in fruit flies enables manipulations of neuronal activities in freely behaving animals. This protocol describes detailed steps for artificial induction of olfactory associative memory in Drosophila larvae. In this protocol, the natural reward signal is substituted by thermogenetic activation of octopaminergic neurons in the brain. In parallel, the odor signal is substituted by optogenetic activation of a specific class of olfactory receptor neurons. Association of reward and odor stimuli is achieved with the concomitant application of blue light and heat that leads to activation of both sets of neurons in living transgenic larvae. Given its operational simplicity and robustness, this method could be utilized to further our knowledge on the neurocircuitry mechanism of memory in the fly brain. PMID:27445732

  19. Artificial Induction of Associative Olfactory Memory by Optogenetic and Thermogenetic Activation of Olfactory Sensory Neurons and Octopaminergic Neurons in Drosophila Larvae.

    PubMed

    Honda, Takato; Lee, Chi-Yu; Honjo, Ken; Furukubo-Tokunaga, Katsuo

    2016-01-01

    The larval brain of Drosophila melanogaster provides an excellent system for the study of the neurocircuitry mechanism of memory. Recent development of neurogenetic techniques in fruit flies enables manipulations of neuronal activities in freely behaving animals. This protocol describes detailed steps for artificial induction of olfactory associative memory in Drosophila larvae. In this protocol, the natural reward signal is substituted by thermogenetic activation of octopaminergic neurons in the brain. In parallel, the odor signal is substituted by optogenetic activation of a specific class of olfactory receptor neurons. Association of reward and odor stimuli is achieved with the concomitant application of blue light and heat that leads to activation of both sets of neurons in living transgenic larvae. Given its operational simplicity and robustness, this method could be utilized to further our knowledge on the neurocircuitry mechanism of memory in the fly brain. PMID:27445732

  20. Whispering galleries and the control of artificial atoms

    NASA Astrophysics Data System (ADS)

    Forrester, Derek Michael; Kusmartsev, Feodor V.

    2016-04-01

    Quantum computation using artificial-atoms, such as novel superconducting circuits, can be sensitively controlled by external electromagnetic fields. These fields and the self-fields attributable to the coupled artificial-atoms influence the amount of quantum correlation in the system. However, control elements that can operate without complete destruction of the entanglement of the quantum-bits are difficult to engineer. Here we investigate the possibility of using closely-spaced-linear arrays of metallic-elliptical discs as whispering gallery waveguides to control artificial-atoms. The discs confine and guide radiation through the array with small notches etched into their sides that act as scatterers. We focus on π-ring artificial-atoms, which can generate their own spontaneous fluxes. We find that the micro-discs of the waveguides can be excited by terahertz frequency fields to exhibit whispering-modes and that a quantum-phase-gate composed of π-rings can be operated under their influence. Furthermore, we gauge the level of entanglement through the concurrence measure and show that under certain magnetic conditions a series of entanglement sudden-deaths and revivals occur between the two qubits. This is important for understanding the stability and life-time of qubit operations using, for example, a phase gate in a hybrid of quantum technologies composed of control elements and artificial-atoms.

  1. Whispering galleries and the control of artificial atoms

    PubMed Central

    Forrester, Derek Michael; Kusmartsev, Feodor V.

    2016-01-01

    Quantum computation using artificial-atoms, such as novel superconducting circuits, can be sensitively controlled by external electromagnetic fields. These fields and the self-fields attributable to the coupled artificial-atoms influence the amount of quantum correlation in the system. However, control elements that can operate without complete destruction of the entanglement of the quantum-bits are difficult to engineer. Here we investigate the possibility of using closely-spaced-linear arrays of metallic-elliptical discs as whispering gallery waveguides to control artificial-atoms. The discs confine and guide radiation through the array with small notches etched into their sides that act as scatterers. We focus on π-ring artificial-atoms, which can generate their own spontaneous fluxes. We find that the micro-discs of the waveguides can be excited by terahertz frequency fields to exhibit whispering-modes and that a quantum-phase-gate composed of π-rings can be operated under their influence. Furthermore, we gauge the level of entanglement through the concurrence measure and show that under certain magnetic conditions a series of entanglement sudden-deaths and revivals occur between the two qubits. This is important for understanding the stability and life-time of qubit operations using, for example, a phase gate in a hybrid of quantum technologies composed of control elements and artificial-atoms. PMID:27122353

  2. Whispering galleries and the control of artificial atoms.

    PubMed

    Forrester, Derek Michael; Kusmartsev, Feodor V

    2016-01-01

    Quantum computation using artificial-atoms, such as novel superconducting circuits, can be sensitively controlled by external electromagnetic fields. These fields and the self-fields attributable to the coupled artificial-atoms influence the amount of quantum correlation in the system. However, control elements that can operate without complete destruction of the entanglement of the quantum-bits are difficult to engineer. Here we investigate the possibility of using closely-spaced-linear arrays of metallic-elliptical discs as whispering gallery waveguides to control artificial-atoms. The discs confine and guide radiation through the array with small notches etched into their sides that act as scatterers. We focus on π-ring artificial-atoms, which can generate their own spontaneous fluxes. We find that the micro-discs of the waveguides can be excited by terahertz frequency fields to exhibit whispering-modes and that a quantum-phase-gate composed of π-rings can be operated under their influence. Furthermore, we gauge the level of entanglement through the concurrence measure and show that under certain magnetic conditions a series of entanglement sudden-deaths and revivals occur between the two qubits. This is important for understanding the stability and life-time of qubit operations using, for example, a phase gate in a hybrid of quantum technologies composed of control elements and artificial-atoms. PMID:27122353

  3. Optical Discs: New Storage Media for Education.

    ERIC Educational Resources Information Center

    Helgerson, Linda W.

    1987-01-01

    Discusses three new advances in the use of optical disc technology in education. Describes the storage formats and capabilities of the videodisc, the compact disc, and the optical write-once disc. Contrasts the three technologies in terms of their production requirements, the hardware involved, and some projected applications in education. (TW)

  4. Electromagnetic Levitation of a Disc

    ERIC Educational Resources Information Center

    Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

    2012-01-01

    This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field…

  5. The aging mouse partially models the aging human spine: lumbar and coccygeal disc height, composition, mechanical properties, and Wnt signaling in young and old mice

    PubMed Central

    Aguilar, Rhiannon; Harland, Robin A.; Bomar, Bradley A.; Silva, Matthew J.

    2014-01-01

    Murine lumbar and coccygeal (tail) regions of spines are commonly used to study cellular signaling of age-related disc diseases, but the tissue-level changes of aging intervertebral discs and vertebrae of each spinal region remain unclear. Furthermore, the impact of aging lumbar and coccygeal discs on Wnt/β-catenin signaling, which is putatively involved in the catabolism of intervertebral discs, is also unclear. We compared disc/vertebrae morphology and mechanics and biochemical composition of intervertebral discs from lumbar and coccygeal regions between young (4–5 mo) and old (20–22 mo) female C57BL/6 mice. Center intervertebral disc height from both regions was greater in old discs than young discs. Compared with young, old lumbar discs had a lower early viscous coefficient (a measure of stiffness) by 40%, while conversely old coccygeal discs were stiffer by 53%. Biochemically, old mice had double the collagen content in lumbar and coccygeal discs of young discs, greater glycosaminoglycan in lumbar discs by 37%, but less glycosaminoglycan in coccygeal discs by 32%. Next, we compared Wnt activity of lumbar and coccygeal discs of 4- to 5-mo and 12- to 14-mo TOPGAL mice. Despite the disc-specific changes, aging decreased Wnt signaling in the nucleus pulposus from both spinal regions by ≥64%. Compared with young, trabecular bone volume/tissue volume and ultimate force were less in old lumbar vertebrae, but greater in old coccygeal vertebrae. Thus intervertebral discs and vertebrae age in a spinal region-dependent manner, but these differential age-related changes may be uncoupled from Wnt signaling. Overall, lumbar and coccygeal regions are not interchangeable in modeling human aging. PMID:24790018

  6. The magnetorotational instability in debris-disc gas

    NASA Astrophysics Data System (ADS)

    Kral, Quentin; Latter, Henrik

    2016-09-01

    Debris discs are commonly swathed in gas, which can be observed in UV, in fine structure lines in FIR, and in resolved maps of CO emission. Carbon and oxygen are overabundant in such gas, but it is severely depleted in hydrogen. As a consequence, its ionization fraction is remarkably high, suggesting that magnetohydrodynamic (MHD) processes could be important. In particular, the gas may be subject to the magnetorotational instability (MRI), and indeed, recent modelling of β Pictoris requires an anomalous viscosity to explain the gas's observed radial structure. In this paper, we explore the possibility that the MRI is active in debris-disc gas and responsible for the observed mass transport. We find that non-ideal MHD and dust-gas interactions play a subdominant role, and that linear instability is viable at certain radii. However, owing to low gas densities, the outer parts of the disc could be stabilized by a weak ambient magnetic field, though it is difficult to constrain such a field. Even if the MRI is stabilized by too strong a field, a magnetocentrifugal wind may be launched in its place, and this could lead to equivalent (non-turbulent) transport. Numerical simulations of the vertically stratified MRI in conditions appropriate to the debris-disc gas should be able to determine the nature of the characteristic behaviour at different radii, and decide on the importance of the MRI (and MHD more generally) on the evolution of these discs.

  7. Syndecan-4 in intervertebral disc and cartilage: Saint or synner?

    PubMed

    Binch, Abbie L A; Shapiro, Irving M; Risbud, Makarand V

    2016-01-01

    The ECM of the intervertebral disc and articular cartilage contains a highly organised network of collagens and proteoglycans which resist compressive forces applied to these tissues. A pathological hallmark of the intervertebral disc is the imbalance between production of anabolic and catabolic factors by the resident cells. This process is thought to be mediated by pro-inflammatory cytokines, predominantly TNF-α and IL-1β, which upregulate expression of matrix degrading enzymes such as MMPs and ADAMTSs. This imbalance ultimately results in tissue degeneration causing failure of the biomechanical function of the tissues. A similar cascade of events is thought to occur in articular cartilage during development of osteoarthritis. Within these skeletal tissues a small, cell surface heparan sulphate proteoglycan; syndecan-4 (SDC4) has been implicated in maintaining physiological functions. However in the degenerating niche of the intervertebral disc and cartilage, dysregulated activities of this molecule may exacerbate pathological changes. Studies in recent years have elucidated a role for SDC4 in mediating matrix degradation in both intervertebral discs and cartilage by controlling ADAMTS-5 function and MMP3 expression. Discourse presented in this review highlights the potential of SDC4 as a possible therapeutic target in slowing the progression of ECM degradation in both degenerative disc disease and osteoarthritis. PMID:26796346

  8. NASA GES DISC DAAC Satellite Data for GIS

    NASA Technical Reports Server (NTRS)

    Nickless, Darryl; Leptoukh, Gregory; Morahan, Michael; Pollack, Nathan; Savtchenko, Andrey; Teng, William

    2005-01-01

    NASA's Goddard Earth Science (GES) Data and Information Services Center (DISC) Distributed Active Archive Center (DAAC) makes available a large and continually growing collection of spatially continuous global satellite observations of environmental parameters. These products include those from the MODIS (Moderate Resolution Imaging Spectroradiometer) on both Terra and Aqua platforms, and the Tropical Rainfall Measuring Mission (TRMM). These data products are well suited for use within Geographic Information Systems (GIS), as both backdrops to cartographic products as well as spatial analysis. However, data format, file size, and other issues have limited their widespread use by traditional GIS users. To address these data usability issues, the GES DISC DAAC recently updated tools and improved documentation of conversion procedures. In addition, the GES DISC DAAC has also been working with a major GIS software vendor to incorporate the ability to read the native Hierarchial Data Format (HDF), the format in which most of the NASA data is stored. The result is the enabling of GIS users to realize the benefit of GES DISC DAAC data without a substantial expenditure in resources to incorporate these data into their GIS. Several documents regarding the potential uses of GES DISC DAAC satellite data in GIS have recently been created. These show the combinations of concurrent data from different satellite products with traditional GIS vector products for given geographic areas. These map products include satellite imagery of Hurricane Isabel and the California wildfires, and can be viewed at http://daac.gsfc.nasa.gov/MODIS/GIS/.

  9. Study of the shape of an optical window in a super-resolution state by electromagnetic-thermal coupled simulation: Effects of melting of an active layer in an optical disc

    SciTech Connect

    Sano, Haruyuki; Shima, Takayuki; Kuwahara, Masashi; Fujita, Yoshiya; Uchiyama, Munehisa; Aono, Yoshiyuki

    2014-04-21

    We performed a multi-physics simulation for the propagation of electromagnetic waves and heat conduction in a super-resolution optical disc that includes an active layer of InSb. Because the change in the optical constant of InSb due to the phase transition is taken into account, the melting of the active layer can be realistically simulated in our calculation. It was found that in the case of an incident light power (P) of 2 mW, a profile of the electric field intensity transmitted through the InSb layer has an asymmetric shape with a narrow peak. This beam-narrowing was suggested to be an essential mechanism of the super-resolution, because a narrower light beam allows the detection of a smaller pit structure than the optical diffraction limit. This beam-narrowing was found to be originating from a small molten region produced in the InSb layer, which works as a mask for light exposure.

  10. Engineered microporosity: enhancing the early regenerative potential of decellularized temporomandibular joint discs.

    PubMed

    Juran, Cassandra M; Dolwick, M Franklin; McFetridge, Peter S

    2015-02-01

    The temporomandibular joint (TMJ) disc is susceptible to numerous pathologies that may lead to structural degradation and jaw dysfunction. The limited treatment options and debilitating nature of severe temporomandibular disorders has been the primary driving force for the introduction and development of TMJ disc tissue engineering as an approach to alleviate this important clinical issue. This study aimed to evaluate the efficacy of laser micropatterning (LMP) ex vivo-derived TMJ disc scaffolds to enhance cellular integration, a major limitation to the development of whole tissue implant technology. LMP was incorporated into the decellularized extracellular matrix scaffold structure using a 40 W CO2 laser ablation system to drill an 8×16 pattern with a bore diameter of 120 μm through the scaffold thickness. Disc scaffolds were seeded with human neonatal-derived umbilical cord mesenchymal stem cells differentiated into chondrocytes at a density of 900 cells per mm(2) and then assessed on days 1, 7, 14, and 21 of culture. Results derived from histology, PicoGreen DNA quantification, and cellular metabolism assays indicate that the LMP scaffolds improve cellular remodeling compared to the unworked scaffold over the 21-day culture period. Mechanical analysis further supports the use of the LMP showing the compressive properties of the LMP constructs closely represent native disc mechanics. The addition of an artificial path of infiltration by LMP culminated in improved chondrocyte adhesion, dispersion, and migration after extended culture aiding in recapitulating the native TMJ disc characteristics. PMID:25319941

  11. Engineered Microporosity: Enhancing the Early Regenerative Potential of Decellularized Temporomandibular Joint Discs

    PubMed Central

    Juran, Cassandra M.; Dolwick, M. Franklin

    2015-01-01

    The temporomandibular joint (TMJ) disc is susceptible to numerous pathologies that may lead to structural degradation and jaw dysfunction. The limited treatment options and debilitating nature of severe temporomandibular disorders has been the primary driving force for the introduction and development of TMJ disc tissue engineering as an approach to alleviate this important clinical issue. This study aimed to evaluate the efficacy of laser micropatterning (LMP) ex vivo-derived TMJ disc scaffolds to enhance cellular integration, a major limitation to the development of whole tissue implant technology. LMP was incorporated into the decellularized extracellular matrix scaffold structure using a 40 W CO2 laser ablation system to drill an 8×16 pattern with a bore diameter of 120 μm through the scaffold thickness. Disc scaffolds were seeded with human neonatal-derived umbilical cord mesenchymal stem cells differentiated into chondrocytes at a density of 900 cells per mm2 and then assessed on days 1, 7, 14, and 21 of culture. Results derived from histology, PicoGreen DNA quantification, and cellular metabolism assays indicate that the LMP scaffolds improve cellular remodeling compared to the unworked scaffold over the 21-day culture period. Mechanical analysis further supports the use of the LMP showing the compressive properties of the LMP constructs closely represent native disc mechanics. The addition of an artificial path of infiltration by LMP culminated in improved chondrocyte adhesion, dispersion, and migration after extended culture aiding in recapitulating the native TMJ disc characteristics. PMID:25319941

  12. Testing hydrodynamics schemes in galaxy disc simulations

    NASA Astrophysics Data System (ADS)

    Few, C. G.; Dobbs, C.; Pettitt, A.; Konstandin, L.

    2016-08-01

    We examine how three fundamentally different numerical hydrodynamics codes follow the evolution of an isothermal galactic disc with an external spiral potential. We compare an adaptive mesh refinement code (RAMSES), a smoothed particle hydrodynamics code (sphNG), and a volume-discretised meshless code (GIZMO). Using standard refinement criteria, we find that RAMSES produces a disc that is less vertically concentrated and does not reach such high densities as the sphNG or GIZMO runs. The gas surface density in the spiral arms increases at a lower rate for the RAMSES simulations compared to the other codes. There is also a greater degree of substructure in the sphNG and GIZMO runs and secondary spiral arms are more pronounced. By resolving the Jeans' length with a greater number of grid cells we achieve more similar results to the Lagrangian codes used in this study. Other alterations to the refinement scheme (adding extra levels of refinement and refining based on local density gradients) are less successful in reducing the disparity between RAMSES and sphNG/GIZMO. Although more similar, sphNG displays different density distributions and vertical mass profiles to all modes of GIZMO (including the smoothed particle hydrodynamics version). This suggests differences also arise which are not intrinsic to the particular method but rather due to its implementation. The discrepancies between codes (in particular, the densities reached in the spiral arms) could potentially result in differences in the locations and timescales for gravitational collapse, and therefore impact star formation activity in more complex galaxy disc simulations.

  13. [Minimally invasive surgery in treatment of lumbar intervertebral disc herniation].

    PubMed

    Rotim, Krešimir; Sajko, Tomislav; Borić, Marta; Subašić, Ante

    2015-01-01

    Surgical treatment of lumbar intervertebral disc herniation is one of the most common neurosurgical procedures. Besides conventional surgical techniques, in the last more than 30 years, different methods with minimal damage to neuromuscular spine structures are being developed and introduced, all having the purpose of reducing postoperative back pain. The advantages of the minimally invasive spine surgery include: possibility of performing procedures under local anaesthesia, reduced hospital stay, limited blood loss with consecutively reduced fibrous tissue development. Patients are capable of return to work and everyday activities early after surgery. From the economical point of view, this kind of treatment is considered to be a cost-effective intervention. Three methods that are being used for treatment of lumbar intervertebral disc herniation are: percutaneous laser disc decompression (PLDD), microdiscectomy using tubular retractor system and selective endoscopic discectomy (SED). Conducted prospective studies have shown that minimally invasive methods are adequate alternative to classic surgical procedures. PMID:26065287

  14. Peripheral disc margin shape and internal disc derangement: imaging correlation in significantly painful discs identified at provocation lumbar discography.

    PubMed

    Bartynski, W S; Rothfus, W E

    2012-06-01

    Annular margin shape is used to characterize lumbar disc abnormality on CT/MR imaging studies. Abnormal discs also have internal derangement including annular degeneration and radial defects. The purpose of this study was to evaluate potential correlation between disc-margin shape and annular internal derangement on post-discogram CT in significantly painful discs encountered at provocation lumbar discography (PLD). Significantly painful discs were encountered at 126 levels in 86 patients (47 male, 39 female) studied by PLD where no prior surgery had been performed and response to intradiscal lidocaine after provocation resulted in either substantial/total relief or no improvement after lidocaine administration. Post-discogram CT and discogram imaging was evaluated for disc-margin characteristics (bulge/protrusion), features of disc internal derangement (radial annular defect [RD: radial tear/fissure/annular gap], annular degeneration) and presence/absence of discographic contrast leakage. In discs with focal protrusion, 50 of 63 (79%) demonstrated Grade 3 RD with 13 (21%) demonstrating severe degenerative change only. In discs with generalized-bulge-only, 48 of 63 (76%) demonstrated degenerative change only (primarily Dallas Grade 3) with 15 of 63 (24%) demonstrating a RD (Dallas Grade 3). Differences were highly statistically significant (p<0.001). Pain elimination with intra-discal lidocaine correlated with discographic contrast leakage (p<0.001). Disc-margin shape correlates with features of internal derangement in significantly painful discs encountered at PLD. Discs with focal protrusion typically demonstrate RD while generalized bulging discs typically demonstrated degenerative changes only (p<0.001). Disc-margin shape may provide an important imaging clue to the cause of chronic discogenic low back pain. PMID:22681741

  15. Peripheral Disc Margin Shape and Internal Disc Derangement: Imaging Correlation in Significantly Painful Discs Identified at Provocation Lumbar Discography

    PubMed Central

    Bartynski, W.S.; Rothfus, W.E.

    2012-01-01

    Summary Annular margin shape is used to characterize lumbar disc abnormality on CT/MR imaging studies. Abnormal discs also have internal derangement including annular degeneration and radial defects. The purpose of this study was to evaluate potential correlation between disc-margin shape and annular internal derangement on post-discogram CT in significantly painful discs encountered at provocation lumbar discography (PLD). Significantly painful discs were encountered at 126 levels in 86 patients (47 male, 39 female) studied by PLD where no prior surgery had been performed and response to intradiscal lidocaine after provocation resulted in either substantial/total relief or no improvement after lidocaine administration. Post-discogram CT and discogram imaging was evaluated for disc-margin characteristics (bulge/protrusion), features of disc internal derangement (radial annular defect [RD: radial tear/fissure/annular gap], annular degeneration) and presence/absence of discographic contrast leakage. In discs with focal protrusion, 50 of 63 (79%) demonstrated Grade 3 RD with 13 (21%) demonstrating severe degenerative change only. In discs with generalized-bulge-only, 48 of 63 (76%) demonstrated degenerative change only (primarily Dallas Grade 3) with 15 of 63 (24%) demonstrating a RD (Dallas Grade 3). Differences were highly statistically significant (p<0.001). Pain elimination with intra-discal lidocaine correlated with discographic contrast leakage (p<0.001). Disc-margin shape correlates with features of internal derangement in significantly painful discs encountered at PLD. Discs with focal protrusion typically demonstrate RD while generalized bulging discs typically demonstrated degenerative changes only (p<0.001). Disc-margin shape may provide an important imaging clue to the cause of chronic discogenic low back pain. PMID:22681741

  16. Sealing arrangement with annular flexible disc

    DOEpatents

    Pennell, William E.; Honigsberg, Charles A.

    1983-01-01

    Fluid sealing arrangements including an annular shaped flexible disc having enlarged edges disposed within channel-shaped annular receptacles which are spaced from one another. The receptacles form an annular region for contacting and containing the enlarged edges of the disc, and the disc is preloaded to a conical configuration. The disc is flexibly and movably supported within the receptacles so that unevenly distributed relative motion between the components containing the receptacles is accommodated without loss of sealing contact between the edges of the disc and the walls of the receptacles.

  17. Reconstitution of Heme Enzymes with Artificial Metalloporphyrinoids.

    PubMed

    Oohora, K; Hayashi, T

    2016-01-01

    An important strategy used in engineering of hemoproteins to generate artificial enzymes involves replacement of heme with an artificial cofactor after removal of the native heme cofactor under acidic conditions. Replacement of heme in an enzyme with a nonnatural metalloporphyrinoid can significantly alter the reactivity of the enzyme. This chapter describes the design and synthesis of three types of artificial metalloporphyrinoid cofactors consisting of mono-, di-, and tri-anionic ligands (tetradehydrocorrin, porphycene, and corrole, respectively). In addition, practical procedures for the preparation of apo-hemoproteins, incorporation of artificial cofactors, and characterization techniques are presented. Furthermore, the representative catalytic activities of artificial enzymes generated by reconstitution of hemoproteins are summarized. PMID:27586344

  18. From the Solar Neighbourhood to the Galactic Disc(s)

    NASA Astrophysics Data System (ADS)

    Casagrande, L.

    2012-08-01

    We present a re-analysis of the Geneva-Copenhagen Survey (GCS), based on improved effective temperature and metallicity scales, which also provide a better match to theoretical isochrones. The latter are used for a Bayesian investigation on stellar ages. With respect to previous analyses, our stars are on average 100 K hotter and 0.1 dex more metal rich, which shifts the peak of the metallicity distribution function (MDF) around the solar value. From Strömgren photometry we are able to derive for the first time a proxy for alpha elements, which enables us to perform a tentative dissection of the chemical thin and thick disc. We find evidence for the latter being composed of an old, mildly but systematically alpha-enhanced population that extends to super solar metallicities. These findings help to constrain different processes potentially relevant in the build-up of the Milky Way disc.

  19. Intradural herniation of lumbar intervertebral discs.

    PubMed

    Hodge, C J; Binet, E F; Kieffer, S A

    1978-12-01

    A case of intradural rupture of a lumbar intervertebral disc is reported, and the literature is reviewed. The majority of intradural disc herniations occur at the L4--5 level. These patients usually have neurologic deficits more severe than those found in the much more common extradural disc herniations. The myelographic picture varies from an irregularly marginated intradural lesion overlying the disc space to a complete block. The common factor allowing intradural disc herniation is probably dense adhesions between the dura and the posterior longitudinal ligament, preventing the more common lateral extradural disc herniation. Intradural disc herniation should be included in the differential diagnosis of lumbar intradural lesions causing nerve root or cauda equina compression. PMID:741242

  20. An Analysis of Burst Disc Pressure Instability

    SciTech Connect

    S. L. Robinson; B. C. Odegard, Jr.; N. r. Moody; S. H. Goods

    2000-06-01

    During the development stage of the 1X Acorn burst disc, burst pressure test results exhibited an unexpected increase of 8 to 14% over times of 90--100 days from initial fabrication. This increase is a concern where design constraints require stability. The disc material, 316L stainless steel sheet, is formed to a dome-like geometry and scored to produce a thin-walled, high-strength ligament. The fracture events controlling burst occur in that ligament. Thus it has been characterized both for tensile properties and microstructure through nanoindentation, magnetic measurements, optical and transmission electron microscopy. These results compare favorably with finite element simulation of the properties of the ligament. The ligament exhibits a highly heterogeneous microstructure; its small volume and microstructural heterogeneity make it difficult to identify which microstructural feature controls fracture and hence burst pressure. Bulk mechanical test specimens were fabricated to emulate mid-ligament properties, and aged at both room and elevated temperatures to characterize and accelerate the temporal behavior of the burst disc. Property changes included yield and ultimate tensile strength increases, and fracture strain decreases with aging. Specimens were subjected to a reversion anneal identical to that given the burst disc to eliminate the martensite phase formed during rolling. Reversion-annealed samples exhibited no change in properties in room temperature or accelerated aging, showing that the reversion-anneal eliminated the aging phenomenon. Aging was analyzed in terms of diffusion controlled precipitate growth kinetics, showing that carbon migration to dislocations is consistent with the strength increases. A vacancy-assisted diffusion mechanism for carbon transport is proposed, giving rise to rapid aging, which replaces interstitial carbon diffusion until excess vacancies from deformation are consumed. Mechanical activation parameters in stress relaxation

  1. The growth of planets by pebble accretion in evolving protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Bitsch, Bertram; Lambrechts, Michiel; Johansen, Anders

    2015-10-01

    The formation of planets depends on the underlying protoplanetary disc structure, which in turn influences both the accretion and migration rates of embedded planets. The disc itself evolves on time scales of several Myr, during which both temperature and density profiles change as matter accretes onto the central star. Here we used a detailed model of an evolving disc to determine the growth of planets by pebble accretion and their migration through the disc. Cores that reach their pebble isolation mass accrete gas to finally form giant planets with extensive gas envelopes, while planets that do not reach pebble isolation mass are stranded as ice giants and ice planets containing only minor amounts of gas in their envelopes. Unlike earlier population synthesis models, our model works without any artificial reductions in migration speed and for protoplanetary discs with gas and dust column densities similar to those inferred from observations. We find that in our nominal disc model, the emergence of planetary embryos preferably should occur after approximately 2 Myr in order to not exclusively form gas giants, but also ice giants and smaller planets. The high pebble accretion rates ensure that critical core masses for gas accretion can be reached at all orbital distances. Gas giant planets nevertheless experience significant reduction in semi-major axes by migration. Considering instead planetesimal accretion for planetary growth, we show that formation time scales are too long to compete with the migration time scales and the dissipation time of the protoplanetary disc. All in all, we find that pebble accretion overcomes many of the challenges in the formation of ice and gas giants in evolving protoplanetary discs. Appendices are available in electronic form at http://www.aanda.org

  2. Determination of the intervertebral disc space from CT images of the lumbar spine

    NASA Astrophysics Data System (ADS)

    Korez, Robert; Å tern, Darko; Likar, Boštjan; Pernuš, Franjo; Vrtovec, Tomaž

    2014-03-01

    Degenerative changes of the intervertebral disc are among the most common causes of low back pain, where for individuals with significant symptoms surgery may be needed. One of the interventions is the total disc replacement surgery, where the degenerated disc is replaced by an artificial implant. For designing implants with good bone contact and continuous force distribution, the morphology of the intervertebral disc space and vertebral body endplates is of considerable importance. In this study we propose a method for the determination of the intervertebral disc space from three-dimensional (3D) computed tomography (CT) images of the lumbar spine. The first step of the proposed method is the construction of a model of vertebral bodies in the lumbar spine. For this purpose, a chain of five elliptical cylinders is initialized in the 3D image and then deformed to resemble vertebral bodies by introducing 25 shape parameters. The parameters are obtained by aligning the chain to the vertebral bodies in the CT image according to image intensity and appearance information. The determination of the intervertebral disc space is finally achieved by finding the planes that fit the endplates of the obtained parametric 3D models, and placing points in the space between the planes of adjacent vertebrae that enable surface reconstruction of the intervertebral disc space. The morphometric analysis of images from 20 subjects yielded 11:3 +/- 2:6, 12:1 +/- 2:4, 12:8 +/- 2:0 and 12:9 +/- 2:7 cm3 in terms of L1-L2, L2-L3, L3-L4 and L4-L5 intervertebral disc space volume, respectively.

  3. Artificial Respiration and Artificial Circulation

    PubMed Central

    Brook, Joseph; Brook, Morris H.; Lopez, Jose F.

    1965-01-01

    A training program in the newer methods of treatment of acute cardiopulmonary emergencies which was developed at the University Hospital, University of Saskatchewan, is reported. Artificial respiration by the chance rescuer, primary and secondary resuscitation, and post-resuscitation measures involving the use of special drugs and equipment by trained personnel are described. Figures and tables designed for wall-mounting and ready reference in an emergency situation are presented. Firstaid ventilatory adjuncts for use by trained personnel are classified and critically appraised, and the propriety of their use is emphasized. A plea is made to the medical profession and allied agencies to assume the responsibility of spreading knowledge of the new techniques more widely. Unless effective treatment is instituted early enough to prevent death or permanent anoxic damage to heart and brain, follow-through therapy will often be fruitless. PMID:14339303

  4. A strong and stretchable self-healing film with self-activated pressure sensitivity for potential artificial skin applications

    PubMed Central

    Hou, Chengyi; Huang, Tao; Wang, Hongzhi; Yu, Hao; Zhang, Qinghong; Li, Yaogang

    2013-01-01

    Artificial skin, which mimics the functions of natural skin, will be very important in the future for robots used by humans in daily life. However, combining skin's pressure sensitivity and mechanical self-healing properties in a man-made material remains a challenging task. Here, we show that graphene and polymers can be integrated into a thin film which mimics both the mechanical self-healing and pressure sensitivity behavior of natural skin without any external power supply. Its ultimate strain and tensile strength are even two and ten times larger than the corresponding values of human skin, respectively. It also demonstrates highly stable sensitivity to a very light touch (0.02 kPa), even in bending or stretching states. PMID:24190511

  5. The Features of Change of the Drag Perturbations of Artificial Satellite Orbits during Extreme Developments of Solar Activity in years 2003-2004

    NASA Astrophysics Data System (ADS)

    Koshkin, N.; Korniychuk, L.; Korobeynikova, E.; Ryabov, M.; Sukhov, K.

    2006-12-01

    In this paper the movement of the artificial satellites of the Earth on low orbits is analyzed which are subject to resistance of a rarefied atmosphere. Temperature and density of terrestrial atmosphere at height of 200-800 km vary over wide range under influence of external conditions. The changes of solar activity are compared to variations of satellite braking (atmospheric drag). In spite of the fact that unequivocal dependence of the atmosphere density behavior from the considered physical factors of solar activity is not present, the attempt is done to find the characteristic periods in these processes. Some periods of fluctuation of an atmosphere density are revealed which can be harmonics of the basic period close to 27 days. Fluctuations of density with the period about 27 days have two close components, which reason is not quite clear. Probably, they are caused by rotation of the Sun and lunar tidal wave in the Earth's atmosphere.

  6. Operative Management of Lumbar Degenerative Disc Disease.

    PubMed

    Lee, Yu Chao; Zotti, Mario Giuseppe Tedesco; Osti, Orso Lorenzo

    2016-08-01

    Lumbar degenerative disc disease is extremely common. Current evidence supports surgery in carefully selected patients who have failed non-operative treatment and do not exhibit any substantial psychosocial overlay. Fusion surgery employing the correct grafting and stabilization techniques has long-term results demonstrating successful clinical outcomes. However, the best approach for fusion remains debatable. There is some evidence supporting the more complex, technically demanding and higher risk interbody fusion techniques for the younger, active patients or patients with a higher risk of non-union. Lumbar disc arthroplasty and hybrid techniques are still relatively novel procedures despite promising short-term and mid-term outcomes. Long-term studies demonstrating superiority over fusion are required before these techniques may be recommended to replace fusion as the gold standard. Novel stem cell approaches combined with tissue engineering therapies continue to be developed in expectation of improving clinical outcomes. Results with appropriate follow-up are not yet available to indicate if such techniques are safe, cost-effective and reliable in the long-term. PMID:27559465

  7. Operative Management of Lumbar Degenerative Disc Disease

    PubMed Central

    Lee, Yu Chao; Osti, Orso Lorenzo

    2016-01-01

    Lumbar degenerative disc disease is extremely common. Current evidence supports surgery in carefully selected patients who have failed non-operative treatment and do not exhibit any substantial psychosocial overlay. Fusion surgery employing the correct grafting and stabilization techniques has long-term results demonstrating successful clinical outcomes. However, the best approach for fusion remains debatable. There is some evidence supporting the more complex, technically demanding and higher risk interbody fusion techniques for the younger, active patients or patients with a higher risk of non-union. Lumbar disc arthroplasty and hybrid techniques are still relatively novel procedures despite promising short-term and mid-term outcomes. Long-term studies demonstrating superiority over fusion are required before these techniques may be recommended to replace fusion as the gold standard. Novel stem cell approaches combined with tissue engineering therapies continue to be developed in expectation of improving clinical outcomes. Results with appropriate follow-up are not yet available to indicate if such techniques are safe, cost-effective and reliable in the long-term. PMID:27559465

  8. [Innervation of the intervertebral disc].

    PubMed

    García-Cosamalón, José; Fernández-Fernández, Javier; González-Martínez, Emilio; Ibáñez-Plágaro, Javier; Robla Costales, Javier; Martínez-Madrigal, Milton; López Muñíz, Alfonso; del Valle, Miguel Enrique; Vega, José Antonio

    2013-01-01

    Until very recently, intervertebral disc innervation was a subject of considerable debate. Nowadays, the introduction of inmunohistochemical techniques associated to specific antibodies and studies with retrograde tracers in nerves have allowed greater understanding of disc innervation in physiological and pathological conditions and also endings characteristics and their patterns of distribution in both situations. The existing controversies regarding structural basis of discogenic pain, have raised the interest of knowing the influence of innervation in back pain from discal origin and its characteristics. Today, we know that pathologic neoinnervation accompanying radial fissures is an important factor in the genesis of discogenic pain; within a complex mechanism in which other neurobiomechemical, inflammatory and biomechanical factors are involved. PMID:23582224

  9. Intervertebral Disc Degeneration

    PubMed Central

    Rannou, François; Lee, Tzong-Shyuan; Zhou, Rui-Hai; Chin, Jennie; Lotz, Jeffrey C.; Mayoux-Benhamou, Marie-Anne; Barbet, Jacques Patrick; Chevrot, Alain; Shyy, John Y.-J.

    2004-01-01

    Degeneration of the intervertebral disk (IVD) is a major pathological process implicated in low back pain and is a prerequisite to disk herniation. Although mechanical stress is an important modulator of the degeneration, the underlying molecular mechanism remains unclear. The association of human IVD degeneration, assessed by magnetic resonance imaging, with annulus fibrosus cell apoptosis and anti-cytochrome c staining revealed that the activation of the mitochondria-dependent apoptosome was a major event in the degeneration process. Mouse models of IVD degeneration were used to investigate the role of the mechanical stress in this process. The application of mechanical overload (1.3 MPa) for 24 hours induced annulus fibrosus cell apoptosis and led to severe degeneration of the mouse disks. Immunostaining revealed cytochrome c release but not Fas-L generation. The role of the caspase-9-dependent mitochondrial pathway in annulus fibrosus cell apoptosis induced by overload was investigated further with the use of cultured rabbit IVD cells in a stretch device. Mechanical overload (15% area change) induced apoptosis with increased caspase-9 activity and decreased mitochondrial membrane potential. Furthermore, Z-LEHD-FMK, a caspase-9 inhibitor, but not Z-IETD-FMK, a caspase-8 inhibitor, attenuated the overload-induced apoptosis. Our results from human samples, mouse models, and annulus fibrosus culture experiments demonstrate that the mechanical overload-induced IVD degeneration is mediated through the mitochondrial apoptotic pathway in IVD cells. PMID:14982845

  10. Hydrodynamic instability in eccentric astrophysical discs

    NASA Astrophysics Data System (ADS)

    Barker, A. J.; Ogilvie, G. I.

    2014-12-01

    Eccentric Keplerian discs are believed to be unstable to three-dimensional hydrodynamical instabilities driven by the time-dependence of fluid properties around an orbit. These instabilities could lead to small-scale turbulence, and ultimately modify the global disc properties. We use a local model of an eccentric disc, derived in a companion paper, to compute the non-linear vertical (`breathing mode') oscillations of the disc. We then analyse their linear stability to locally axisymmetric disturbances for any disc eccentricity and eccentricity gradient using a numerical Floquet method. In the limit of small departures from a circular reference orbit, the instability of an isothermal disc is explained analytically. We also study analytically the small-scale instability of an eccentric neutrally stratified polytropic disc with any polytropic index using a Wentzel-Kramers-Brillouin (WKB) approximation. We find that eccentric discs are generically unstable to the parametric excitation of small-scale inertial waves. The non-linear evolution of these instabilities should be studied in numerical simulations, where we expect them to lead to a decay of the disc eccentricity and eccentricity gradient as well as to induce additional transport and mixing. Our results highlight that it is essential to consider the three-dimensional structure of eccentric discs, and their resulting vertical oscillatory flows, in order to correctly capture their evolution.

  11. Multi-bioindicators to assess soil microbial activity in the context of an artificial groundwater recharge with treated wastewater: a large-scale pilot experiment.

    PubMed

    Michel, Caroline; Joulian, Catherine; Ollivier, Patrick; Nyteij, Audrey; Cote, Rémi; Surdyk, Nicolas; Hellal, Jennifer; Casanova, Joel; Besnard, Katia; Rampnoux, Nicolas; Garrido, Francis

    2014-06-28

    In the context of artificial groundwater recharge, a reactive soil column at pilot-scale (4.5 m depth and 3 m in diameter) fed by treated wastewater was designed to evaluate soil filtration ability. Here, as a part of this project, the impact of treated wastewater filtration on soil bacterial communities and the soil's biological ability for wastewater treatment as well as the relevance of the use of multi-bioindicators were studied as a function of depth and time. Biomass; bacterial 16S rRNA gene diversity fingerprints; potential nitrifying, denitrifying, and sulfate-reducing activities; and functional gene (amo, nir, nar, and dsr) detection were analyzed to highlight the real and potential microbial activity and diversity within the soil column. These bioindicators show that topsoil (0 to 20 cm depth) was the more active and the more impacted by treated wastewater filtration. Nitrification was the main activity in the pilot. No sulfate-reducing activity or dsr genes were detected during the first 6 months of wastewater application. Denitrification was also absent, but genes of denitrifying bacteria were detected, suggesting that the denitrifying process may occur rapidly if adequate chemical conditions are favored within the soil column. Results also underline that a dry period (20 days without any wastewater supply) significantly impacted soil bacterial diversity, leading to a decrease of enzyme activities and biomass. Finally, our work shows that treated wastewater filtration leads to a modification of the bacterial genetic and functional structures in topsoil. PMID:24608565

  12. Temporal changes of mechanical signals and extracellular composition in human intervertebral disc during degenerative progression

    PubMed Central

    Zhu, Qiaoqiao; Gao, Xin; Gu, Weiyong

    2014-01-01

    In this study, a three-dimensional finite element model was used to investigate the changes in tissue composition and mechanical signals within human lumbar intervertebral disc during the degenerative progression. This model was developed based on the cell-activity coupled mechano-electrochemical mixture theory. The disc degeneration was simulated by lowering nutrition levels at disc boundaries, and the temporal and spatial distributions of the fixed charge density, water content, fluid pressure, Von Mises stress, and disc deformation were analyzed. Results showed that fixed charge density, fluid pressure, and water content decreased significantly in the nucleus pulposus (NP) and the inner to middle annulus fibrosus (AF) regions of the degenerative disc. It was found that, with degenerative progression, the Von Mises stress (relative to that at healthy state) increased within the disc, with a larger increase in the outer AF region. Both the disc volume and height decreased with the degenerative progression. The predicted results of fluid pressure change in the NP were consistent with experimental findings in the literature. The knowledge of the variations of temporal and spatial distributions of composition and mechanical signals within the human IVDs provide a better understanding of the progression of disc degeneration. PMID:25305690

  13. Molecular immunotherapy might shed a light on the treatment strategies for disc degeneration and herniation.

    PubMed

    Sun, Zhen; Liu, Zhi-Heng; Chen, Yu-fei; Zhang, Yong-zhao; Wan, Zhong-yuan; Zhang, Wei-lin; Che, Lu; Liu, Xu; Wang, Hai-Qiang; Luo, Zhuo-Jing

    2013-09-01

    Despite surgical discectomy is one of the most effective treatments for intervertebral disc degeneration and lumbar disc herniation, a number of patients still complain of reserved low back pain, sciatica and numbness post-operatively with decreased life quality. Sciatica in patients with disc herniation is not only due to mechanical compression from herniated nucleus pulposus, but chemical and immunity agents. The intervertebral disc is composed of annulus fibrosus in the wedge and gelatinous nucleus pulposus in the centre with cartilage endplate sandwiched. Similar to other immune privilege organs, human intervertebral disc is one of the biggest avascular structures with FasL expression. Moreover, FasL-Fas and TRAIL death pathways might play roles in the machinery of immune privilege of the disc. We found that down-regulated miR-155 promotes Fas-mediated apoptosis in disc degeneration. Furthermore, once exposed to human immune system, nucleus pulposus can activate multiple specific and non-specific immune responses with cellular and fluid immune cells and molecules involved. Taken together, we hypothesize that a combined molecular immunotherapy with local and systemic immunity regulators might shed a novel light on the treatment strategies for disc degeneration and herniation. PMID:23849654

  14. Planetesimal formation in self-gravitating discs - dust trapping by vortices

    NASA Astrophysics Data System (ADS)

    Gibbons, P. G.; Mamatsashvili, G. R.; Rice, W. K. M.

    2015-11-01

    The mechanism through which metre-sized boulders grow to km-sized planetesimals in protoplanetary discs is a subject of active research, since it is critical for planet formation. To avoid spiralling into the protostar due to aerodynamic drag, objects must rapidly grow from cm-sized pebbles, which are tightly coupled to the gas, to large boulders of 1-100 m in diameter. It is already well known that overdensities in the gaseous component of the disc provide potential sites for the collection of solids, and that significant density structures in the gaseous component of the disc (e.g. spiral density waves) can trap solids efficiently enough for the solid component of the disc to undergo further gravitational collapse due to their own self-gravity. In this work, we employ the PENCIL CODE to conduct local shearing sheet simulations of massive self-gravitating protoplanetary discs, to study the effect of anticyclonic transient vortices, or eddies, on the evolution of solids in these discs. We find that these types of structures are extremely efficient at concentrating small and intermediate-sized dust particles with friction times comparable to, or less than, the local orbital period of the disc. This can lead to significant over-densities in the solid component of the disc, with density enhancements comparable to, and even higher, than those within spiral density waves; increasing the rate of gravitational collapse of solids into bound structures.

  15. Artificial neural networks in neurosurgery.

    PubMed

    Azimi, Parisa; Mohammadi, Hasan Reza; Benzel, Edward C; Shahzadi, Sohrab; Azhari, Shirzad; Montazeri, Ali

    2015-03-01

    Artificial neural networks (ANNs) effectively analyze non-linear data sets. The aimed was A review of the relevant published articles that focused on the application of ANNs as a tool for assisting clinical decision-making in neurosurgery. A literature review of all full publications in English biomedical journals (1993-2013) was undertaken. The strategy included a combination of key words 'artificial neural networks', 'prognostic', 'brain', 'tumor tracking', 'head', 'tumor', 'spine', 'classification' and 'back pain' in the title and abstract of the manuscripts using the PubMed search engine. The major findings are summarized, with a focus on the application of ANNs for diagnostic and prognostic purposes. Finally, the future of ANNs in neurosurgery is explored. A total of 1093 citations were identified and screened. In all, 57 citations were found to be relevant. Of these, 50 articles were eligible for inclusion in this review. The synthesis of the data showed several applications of ANN in neurosurgery, including: (1) diagnosis and assessment of disease progression in low back pain, brain tumours and primary epilepsy; (2) enhancing clinically relevant information extraction from radiographic images, intracranial pressure processing, low back pain and real-time tumour tracking; (3) outcome prediction in epilepsy, brain metastases, lumbar spinal stenosis, lumbar disc herniation, childhood hydrocephalus, trauma mortality, and the occurrence of symptomatic cerebral vasospasm in patients with aneurysmal subarachnoid haemorrhage; (4) the use in the biomechanical assessments of spinal disease. ANNs can be effectively employed for diagnosis, prognosis and outcome prediction in neurosurgery. PMID:24987050

  16. Alteration of blue pigment in artificial iris in ocular prosthesis: effect of paint, drying method and artificial aging.

    PubMed

    Goiato, Marcelo Coelho; Fernandes, Aline Úrsula Rocha; dos Santos, Daniela Micheline; Hadadd, Marcela Filié; Moreno, Amália; Pesqueira, Aldiéris Alves

    2011-02-01

    The artificial iris is the structure responsible for the dissimulation and aesthetics of ocular prosthesis. The objective of the present study was to evaluate the color stability of artificial iris of microwaveable polymerized ocular prosthesis, as a function of paint type, drying method and accelerated aging. A total of 40 discs of microwaveable polymerized acrylic resin were fabricated, and divided according to the blue paint type (n = 5): hydrosoluble acrylic, nitrocellulose automotive, hydrosoluble gouache and oil paints. Paints where dried either at natural or at infrared light bulb method. Each specimen was constituted of one disc in colorless acrylic resin and another colored with a basic sclera pigment. Painting was performed in one surface of one of the discs. The specimens were submitted to an artificial aging chamber under ultraviolet light, during 1008 h. A reflective spectrophotometer was used to evaluate color changes. Data were evaluated by 3-way repeated-measures ANOVA and the Tukey HSD test (α = 0.05). All paints suffered color alteration. The oil paint presented the highest color resistance to artificial aging regardless of drying method. PMID:21081281

  17. Proto-planetary disc evolution and dispersal

    NASA Astrophysics Data System (ADS)

    Rosotti, Giovanni Pietro

    2015-05-01

    Planets form from gas and dust discs in orbit around young stars. The timescale for planet formation is constrained by the lifetime of these discs. The properties of the formed planetary systems depend thus on the evolution and final dispersal of the discs, which is the main topic of this thesis. Observations reveal the existence of a class of discs called "transitional", which lack dust in their inner regions. They are thought to be the last stage before the complete disc dispersal, and hence they may provide the key to understanding the mechanisms behind disc evolution. X-ray photoevaporation and planet formation have been studied as possible physical mechanisms responsible for the final dispersal of discs. However up to now, these two phenomena have been studied separately, neglecting any possible feedback or interaction. In this thesis we have investigated what is the interplay between these two processes. We show that the presence of a giant planet in a photo-evaporating disc can significantly shorten its lifetime, by cutting the inner regions from the mass reservoir in the exterior of the disc. This mechanism produces transition discs that for a given mass accretion rate have larger holes than in models considering only X-ray photo-evaporation, constituting a possible route to the formation of accreting transition discs with large holes. These discs are found in observations and still constitute a puzzle for the theory. Inclusion of the phenomenon called "thermal sweeping", a violent instability that can destroy a whole disc in as little as 10 4 years, shows that the outer disc left can be very short-lived (depending on the X-ray luminosity of the star), possibly explaining why very few non accreting transition discs are observed. However the mechanism does not seem to be efficient enough to reconcile with observations. In this thesis we also show that X-ray photo-evaporation naturally explains the observed correlation between stellar masses and accretion

  18. Factors regulating viable cell density in the intervertebral disc: blood supply in relation to disc height

    PubMed Central

    Boubriak, Olga A; Watson, Natasha; Sivan, Sarit S; Stubbens, Naomi; Urban, Jill P G

    2013-01-01

    The intervertebral disc is an avascular tissue, maintained by a small population of cells that obtain nutrients mainly by diffusion from capillaries at the disc–vertebral body interface. Loss of this nutrient supply is thought to lead to disc degeneration, but how nutrient supply influences viable cell density is unclear. We investigated two factors that influence nutrient delivery to disc cells and hence cell viability: disc height and blood supply. We used bovine caudal discs as our model as these show a gradation in disc height. We found that although disc height varied twofold from the largest to the smallest disc studied, it had no significant effect on cell density, unlike the situation found in articular cartilage. The density of blood vessels supplying the discs was markedly greater for the largest disc than the smallest disc, as was the density of pores allowing capillary penetration through the bony endplate. Results indicate that changes in blood vessels in the vertebral bodies supplying the disc, as well as changes in endplate architecture appear to influence density of cells in intervertebral discs. PMID:23311982

  19. DISC1 regulates astrogenesis in the embryonic brain via modulation of RAS/MEK/ERK signaling through RASSF7.

    PubMed

    Wang, Shukun; Liang, Qingli; Qiao, Huimin; Li, Hong; Shen, Tianjin; Ji, Fen; Jiao, Jianwei

    2016-08-01

    Disrupted in schizophrenia 1 (DISC1) is known as a high susceptibility gene for schizophrenia. Recent studies have indicated that schizophrenia might be caused by glia defects and dysfunction. However, there is no direct evidence of a link between the schizophrenia gene DISC1 and gliogenesis defects. Thus, an investigation into the involvement of DISC1 (a ubiquitously expressed brain protein) in astrogenesis during the late stage of mouse embryonic brain development is warranted. Here, we show that suppression of DISC1 expression represses astrogenesis in vitro and in vivo, and that DISC1 overexpression substantially enhances the process. Furthermore, mouse and human DISC1 overexpression rescued the astrogenesis defects caused by DISC1 knockdown. Mechanistically, DISC1 activates the RAS/MEK/ERK signaling pathway via direct association with RASSF7. Also, the pERK complex undergoes nuclear translocation and influences the expression of genes related to astrogenesis. In summary, our results demonstrate that DISC1 regulates astrogenesis by modulating RAS/MEK/ERK signaling via RASSF7 and provide a framework for understanding how DISC1 dysfunction might lead to neuropsychiatric diseases. PMID:27287808

  20. Effect of disc degeneration on the muscle recruitment pattern in upright posture: a computational analysis.

    PubMed

    Kim, Young Eun; Choi, Hae Won

    2015-01-01

    Based on the sensor driving control mechanism model, the effect of disc degeneration on the trunk muscle recruitment (TMR) pattern was analysed in erect standing posture. A previously developed computational model was used for this analysis, with modifications incorporating the T12-L1 motion segment and additional muscle fascicles. To generate disc degeneration at three different levels (L3-L4, L4-L5, or L5-S1), the material properties of the ground matrix of the annulus and bulk modulus of the nucleus were reduced. The finite element method combined with an optimization technique was applied to calculate the muscle forces. Minimization of deviations in the averaged tensile stress in the annulus fibres at the outermost layer in the five discs was selected for muscle force calculations. The results indicated that the disc degeneration noticeably increased the activation of the superficial muscle (IT and R) even though there was no clear change in the longissimus thoracis. Unlike some of the superficial muscles, activation in the deep muscles (multifidus (ML, MS, MT), LL and Q) was decreased. The change in TMR pattern generated an intervertebral disc angle difference and nucleus pressure increased in the upper level. These differences are expected to be functional in that they reduce the stress at the degenerated disc by changing the muscle activation, which slows down the progress of disc degeneration. PMID:25025614

  1. Intervertebral disc extrusion in six cats.

    PubMed

    Knipe, M F; Vernau, K M; Hornof, W J; LeCouteur, R A

    2001-09-01

    Existing reports concerning intervertebral disc disease (IVDD) have focused almost exclusively on dogs, although a small number of individual case reports of IVDD of cats has been published. The medical records of six cats with IVDD were reviewed. Radiographic studies confirmed narrowed intervertebral disc spaces, mineralised intervertebral discs, and one or more extradural compressive lesions of the spinal cord in each cat. All disc extrusions were located in the thoracolumbar region. Surgical decompression of the spinal cord was achieved in all cats by means of hemilaminectomy and removal of compressive extradural material confirmed to be degenerative disc material. Good to excellent neurological recovery was noted in five of the six cats included in this report. Based on this review, it appears that IVDD of cats has many similarities to IVDD of dogs, and that healthy cats with acute intervertebral disc extrusion(s) respond favourably to surgical decompression of the spinal cord. PMID:11876633

  2. Relationship between Initial Telomere Length, Initial Telomerase Activity, Age, and Replicative Capacity of Nucleus Pulposus Chondrocytes in Human Intervertebral Discs: What Is a Predictor of Replicative Potential?

    PubMed Central

    Lee, Jun-Seok; Jeong, Seo-Won; Cho, Sung-Wook; Juhn, Joon-Pyo; Kim, Ki-Won

    2015-01-01

    There is evidence that telomere length (TL), telomerase activity (TA), and age are related to the replicative potential of human nucleus pulposus chondrocytes (NPCs). However, it has not yet been established if any of these factors can serve as predictors of the replicative potential of NPCs. To establish predictors of the replicative potential of NPCs, we evaluated potential relationships between replicative capacity of NPCs, initial TL (telomere length at the first passage), initial TA (telomerase activity at the first passage), and age. Nucleus pulposus specimens were obtained from 14 patients of various ages undergoing discectomy. NPCs were serially cultivated until the end of their replicative lifespans. Relationships among cumulative population doubling level (PDL), initial TL, initial TA, and age were analyzed. Initial TA was negatively correlated with age (r = -0.674, P = 0.008). However, no correlation between initial TL and age was observed. Cumulative PDL was also negatively correlated with age (r = -0.585, P = 0.028). Although the cumulative PDL appeared to increase with initial TL or initial TA, this trend was not statistically significant. In conclusion, age is the sole predictor of the replicative potential of human NPCs, and replicative potential decreases with age. Initial TL and initial TA are not predictors of replicative potential, and can serve only as reference values. PMID:26633809

  3. Disc repositioning: does it really work?

    PubMed

    Gonçalves, João Roberto; Cassano, Daniel Serra; Rezende, Luciano; Wolford, Larry M

    2015-02-01

    Although limited, there is evidence to support the assumption that temporomandibular joint (TMJ) articular disc repositioning indeed works; to date, there is no evidence that TMJ articular disc repositioning does not work. Despite the controversy among professionals in private practice and academia, TMJ articular disc repositioning is a procedure based on (still limited) evidence; the opposition is based solely on clinical preference and influenced by the ability to perform it or not. PMID:25483446

  4. NASA GES DISC Hurricane Web Portal

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Leptoukh, G.; Ostrenga, D.; Rui, H.; Hulka, J.; Carlaw, L.

    2006-12-01

    This presentation will describe recent activities at the NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC) to support hurricane monitoring, research and outreach activities. A newly developed web portal (URL: http://disc.sci.gsfc.nasa.gov/hurricane/) is designed for viewing and studying hurricanes by utilizing various measurements by NASA remote-sensing instruments. The portal consists of five main components: - Current conditions (in pre-selected regions and updated daily): the latest maps, animation and profiles from NASA satellites. At present, images or plots created using data from TRMM, AIRS, MODIS, MLS and CloudSat are available. Later, data from OMI and other instruments will be added. A new feature will be added to allow users to easily download/subset data associated with these images. - Past hurricane archive: maps, animation and profiles of past hurricanes were created using data from TRMM, AIRS, MODIS, MLS and CloudSat, allowing users to explore past hurricanes and download/subset data if necessary. - Science focus: examples/stories describing data usage in hurricane monitoring and research - Tools: descriptions and links of a number of in-house developed tools for hurricane exploration and event-based data ordering. For example, the GES-DISC Interactive Online Visualization ANd aNalysis Infrastructure (Giovanni, URL: http://giovanni.gsfc.nasa.gov), a series of online visualization and analysis systems, allows users to access data ranging from near-real-time to historical archives and generate customized analysis maps, plots and data on the fly over the Internet. A hurricane instance of Giovanni is under development. Mirador (URL: http://g0dup05u.ecs.nasa.gov/OPS/mirador/) is another in-house developed tool that offers a simplified interface for searching, browsing, and ordering Earth science data at NASA GES DICS. Users can do event based (e.g., entering a hurricane name) search and order data. - Hurricane viewer: provides

  5. Accretion Discs Show Their True Colours

    NASA Astrophysics Data System (ADS)

    2008-07-01

    Quasars are the brilliant cores of remote galaxies, at the hearts of which lie supermassive black holes that can generate enough power to outshine the Sun a trillion times. These mighty power sources are fuelled by interstellar gas, thought to be sucked into the hole from a surrounding 'accretion disc'. A paper in this week's issue of the journal Nature, partly based on observations collected with ESO's Very Large Telescope, verifies a long-standing prediction about the intensely luminous radiation emitted by these accretion discs. Uncovering the disc ESO PR Photo 21/08 Uncovering the inner disc "Astronomers were puzzled by the fact that the best models of these discs couldn't quite be reconciled with some of the observations, in particular, with the fact that these discs did not appear as blue as they should be," explains lead-author Makoto Kishimoto. Such a discrepancy could be the signal that there was something very wrong with the models. With his colleagues, he investigated this discrepancy by studying the polarised light from six quasars. This enabled them to demonstrate that the disc spectrum is as blue as predicted. "The crucial observational difficulty here has been that the disc is surrounded by a much larger torus containing hot dust, whose light partly outshines that of the disc," says Kishimoto. "Because the light coming from the disc is scattered in the disc vicinity and thus polarised, by observing only polarised light from the quasars, one can uncover the buried light from the disc." In a similar way that a fisherman would wear polarised sunglasses to help get rid of the glare from the water surface and allow him to see more clearly under the water, the filter on the telescope allowed the astronomers to see beyond surrounding clouds of dust and gas to the blue colour of the disc in infrared light. The observations were done with the FORS and ISAAC instruments on one of the 8.2-m Unit Telescopes of ESO's Very Large Telescope, located in the Atacama

  6. On the evolution of the protolunar disc.

    PubMed

    Ward, William R

    2014-09-13

    The structure and viscous evolution of a post-impact, protolunar disc is examined. The equations for a silicate disc in two-phase (vapour-liquid) equilibrium are employed to derive an analytical solution to vertical structure. Both a vertically mixed phase disc and a stratified disc, where a magma layer exists in the mid-plane surrounded by a vapour reservoir, are considered. The former largely reproduces the low gas mass fraction, x≪1, profiles of the disc described in earlier literature that proposed that the disc would hover on the brink of gravitational instability. In the latter, the vapour layer has x∼1 and is generally gravitationally stable, while the magma layer is vigorously unstable. The viscous evolution of the stratified model is then explored. Initially, the disc quickly settles to a quasi-steady state with a vapour reservoir containing the majority of the disc mass. The magma layer viscously spreads on a time scale of approximately 3-4 years, during which vapour continuously condenses into droplets that settle to the mid-plane, maintaining the magma surface density in spite of disc spreading. Material flowing inwards is accreted by the Earth; material flowing outwards past the Roche boundary can become incorporated into accreting moonlets. This evolution persists until the vapour reservoir is depleted in approximately 50-100 years, depending on its initial mass. PMID:25114314

  7. The quiescent phase of galactic disc growth

    NASA Astrophysics Data System (ADS)

    Aumer, Michael; Binney, James; Schönrich, Ralph

    2016-07-01

    We perform a series of controlled N-body simulations of growing disc galaxies within non-growing, live dark matter haloes of varying mass and concentration. Our initial conditions include either a low-mass disc or a compact bulge. New stellar particles are continuously added on near-circular orbits to the existing disc, so spiral structure is continuously excited. To study the effect of combined spiral and giant molecular cloud (GMC) heating on the discs, we introduce massive, short-lived particles that sample a GMC mass function. An isothermal gas component is introduced for a subset of the models. We perform a resolution study and vary parameters governing the GMC population, the histories of star formation and radial scale growth. Models with GMCs and standard values for the disc mass and halo density provide the right level of self-gravity to explain the age-velocity dispersion relation of the solar neighbourhood (Snhd). GMC heating generates remarkably exponential vertical profiles with scaleheights that are radially constant and agree with observations of galactic thin discs. GMCs are also capable of significantly delaying bar formation. The amount of spiral-induced radial migration agrees with what is required for the metallicity distribution of the Snhd. However, in our standard models, the outward-migrating populations are not hot enough vertically to create thick discs. Thick discs can form in models with high baryon fractions, but the corresponding bars are too long, the young stellar populations too hot and the discs flare considerably.

  8. The quiescent phase of galactic disc growth

    NASA Astrophysics Data System (ADS)

    Aumer, Michael; Binney, James; Schönrich, Ralph

    2016-04-01

    We perform a series of controlled N-body simulations of growing disc galaxies within non-growing, live dark matter haloes of varying mass and concentration. Our initial conditions include either a low-mass disc or a compact bulge. New stellar particles are continuously added on near-circular orbits to the existing disc, so spiral structure is continuously excited. To study the effect of combined spiral and giant molecular cloud (GMC) heating on the discs we introduce massive, short-lived particles that sample a GMC mass function. An isothermal gas component is introduced for a subset of the models. We perform a resolution study and vary parameters governing the GMC population, the histories of star formation and radial scale growth. Models with GMCs and standard values for the disc mass and halo density provide the right level of self-gravity to explain the age velocity dispersion relation of the Solar neighbourhood (Snhd). GMC heating generates remarkably exponential vertical profiles with scaleheights that are radially constant and agree with observations of galactic thin discs. GMCs are also capable of significantly delaying bar formation. The amount of spiral induced radial migration agrees with what is required for the metallicity distribution of the Snhd. However, in our standard models the outward migrating populations are not hot enough vertically to create thick discs. Thick discs can form in models with high baryon fractions, but the corresponding bars are too long, the young stellar populations too hot and the discs flare considerably.

  9. MicroRNA in intervertebral disc degeneration.

    PubMed

    Li, Zheng; Yu, Xin; Shen, Jianxiong; Chan, Matthew T V; Wu, William Ka Kei

    2015-06-01

    Aetiology of intervertebral disc degeneration (IDD) is complex, with genetic, developmental, biochemical and biomechanical factors contributing to the disease process. It is becoming obvious that epigenetic processes influence evolution of IDD as strongly as the genetic background. Deregulated phenotypes of nucleus pulposus cells, including differentiation, migration, proliferation and apoptosis, are involved in all stages of progression of human IDD. Non-coding RNAs, including microRNAs, have recently been recognized as important regulators of gene expression. Research into roles of microRNAs in IDD has been very active over the past 5 years. Our review summarizes current research enlightenment towards understanding roles of microRNAs in regulating nucleus pulposus cell functions in IDD. These exciting findings support the notion that specific modulation of microRNAs may represent an attractive approach for management of IDD. PMID:25736871

  10. Sonic hedgehog functions upstream of disrupted-in-schizophrenia 1 (disc1): implications for mental illness

    PubMed Central

    Boyd, Penelope J.; Cunliffe, Vincent T.; Roy, Sudipto; Wood, Jonathan D.

    2015-01-01

    ABSTRACT DISRUPTED-IN-SCHIZOPHRENIA (DISC1) has been one of the most intensively studied genetic risk factors for mental illness since it was discovered through positional mapping of a translocation breakpoint in a large Scottish family where a balanced chromosomal translocation was found to segregate with schizophrenia and affective disorders. While the evidence for it being central to disease pathogenesis in the original Scottish family is compelling, recent genome-wide association studies have not found evidence for common variants at the DISC1 locus being associated with schizophrenia in the wider population. It may therefore be the case that DISC1 provides an indication of biological pathways that are central to mental health issues and functional studies have shown that it functions in multiple signalling pathways. However, there is little information regarding factors that function upstream of DISC1 to regulate its expression and function. We herein demonstrate that Sonic hedgehog (Shh) signalling promotes expression of disc1 in the zebrafish brain. Expression of disc1 is lost in smoothened mutants that have a complete loss of Shh signal transduction, and elevated in patched mutants which have constitutive activation of Shh signalling. We previously demonstrated that disc1 knockdown has a dramatic effect on the specification of oligodendrocyte precursor cells (OPC) in the hindbrain and Shh signalling is known to be essential for the specification of these cells. We show that disc1 is prominently expressed in olig2-positive midline progenitor cells that are absent in smo mutants, while cyclopamine treatment blocks disc1 expression in these cells and mimics the effect of disc1 knock down on OPC specification. Various features of a number of psychiatric conditions could potentially arise through aberrant Hedgehog signalling. We therefore suggest that altered Shh signalling may be an important neurodevelopmental factor in the pathobiology of mental illness. PMID

  11. Sonic hedgehog functions upstream of disrupted-in-schizophrenia 1 (disc1): implications for mental illness.

    PubMed

    Boyd, Penelope J; Cunliffe, Vincent T; Roy, Sudipto; Wood, Jonathan D

    2015-01-01

    DISRUPTED-IN-SCHIZOPHRENIA (DISC1) has been one of the most intensively studied genetic risk factors for mental illness since it was discovered through positional mapping of a translocation breakpoint in a large Scottish family where a balanced chromosomal translocation was found to segregate with schizophrenia and affective disorders. While the evidence for it being central to disease pathogenesis in the original Scottish family is compelling, recent genome-wide association studies have not found evidence for common variants at the DISC1 locus being associated with schizophrenia in the wider population. It may therefore be the case that DISC1 provides an indication of biological pathways that are central to mental health issues and functional studies have shown that it functions in multiple signalling pathways. However, there is little information regarding factors that function upstream of DISC1 to regulate its expression and function. We herein demonstrate that Sonic hedgehog (Shh) signalling promotes expression of disc1 in the zebrafish brain. Expression of disc1 is lost in smoothened mutants that have a complete loss of Shh signal transduction, and elevated in patched mutants which have constitutive activation of Shh signalling. We previously demonstrated that disc1 knockdown has a dramatic effect on the specification of oligodendrocyte precursor cells (OPC) in the hindbrain and Shh signalling is known to be essential for the specification of these cells. We show that disc1 is prominently expressed in olig2-positive midline progenitor cells that are absent in smo mutants, while cyclopamine treatment blocks disc1 expression in these cells and mimics the effect of disc1 knock down on OPC specification. Various features of a number of psychiatric conditions could potentially arise through aberrant Hedgehog signalling. We therefore suggest that altered Shh signalling may be an important neurodevelopmental factor in the pathobiology of mental illness. PMID:26405049

  12. Use of adipose stem cells and polylactide discs for tissue engineering of the temporomandibular joint disc

    PubMed Central

    Mäenpää, Katja; Ellä, Ville; Mauno, Jari; Kellomäki, Minna; Suuronen, Riitta; Ylikomi, Timo; Miettinen, Susanna

    2010-01-01

    There is currently no suitable replacement for damaged temporomandibular joint (TMJ) discs after discectomy. In the present study, we fabricated bilayer biodegradable polylactide (PLA) discs comprising a non-woven mat of poly(L/D)lactide (P(L/D)LA) 96/4 and a P(L/DL)LA 70/30 membrane plate. The PLA disc was examined in combination with adipose stem cells (ASCs) for tissue engineering of the fibrocartilaginous TMJ disc in vitro. ASCs were cultured in parallel in control and chondrogenic medium for a maximum of six weeks. Relative expression of the genes, aggrecan, type I collagen and type II collagen present in the TMJ disc extracellular matrix increased in the ASC-seeded PLA discs in the chondrogenic medium. The hypertrophic marker, type X collagen, was moderately induced. Alcian blue staining showed accumulation of sulphated glycosaminoglycans. ASC differentiation in the PLA discs was close to that observed in pellet cultures. Comparison of the mRNA levels revealed that the degree of ASC differentiation was lower than that in TMJ disc-derived cells and tissue. The pellet format supported the phenotype of the TMJ disc-derived cells under chondrogenic conditions and also enhanced their hyalinization potential, which is considered part of the TMJ disc degeneration process. Accordingly, the combination of ASCs and PLA discs has potential for the development of a tissue-engineered TMJ disc replacement. PMID:19474082

  13. Total Disc Arthroplasty for Treating Lumbar Degenerative Disc Disease

    PubMed Central

    2015-01-01

    Study Design Lumber disc arthroplasty is a technological advancement that has occurred in the last decade to treat lumbar degenerative disk diseases. Purpose The aim of this retrospective study was to establish the impact and outcomes of managing patients with lumbar degenerative disk disease who have been treated with lumbar total disc arthroplasty (TDA). Overview of Literature Several studies have shown promising results following this surgery. Methods We reviewed the files of 104 patients at the Department of Neurosurgery in Colmar (France) who had been operated on by lumbar spine arthroplasty (Prodisc) between April 2002 and October 2008. Results Among the 104 patients, 67 were female and 37 were male with an average age of 33.1 years. We followed the cases for a mean of 20 months. The most frequent level of discopathy was L4-L5 with 62 patients (59.6%) followed by L5-S1 level with 52 patients (50%). Eighty-three patients suffered from low back pain, 21 of which were associated with radiculopathy. The status of 82 patients improved after surgery according to the Oswestry Disability Index score, and 92 patients returned to work. Conclusions The results indicate that TDA is a good alternative treatment for lumbar spine disk disease, particularly for patients with disabling and chronic low back pain. This technique contributes to improve living conditions with correct patient selection for surgery. PMID:25705336

  14. Total Disc Replacement in Lumbar Degenerative Disc Diseases

    PubMed Central

    2015-01-01

    More than 10 years have passed since lumbar total disc replacement (LTDR) was introduced for the first time to the world market for the surgical management of lumbar degenerative disc disease (DDD). It seems like the right time to sum up the relevant results in order to understand where LTDR stands on now, and is heading forward to. The pathogenesis of DDD has been currently settled, but diagnosis and managements are still controversial. Fusion is recognized as golden standard of surgical managements but has various kinds of shortcomings. Lately, LTDR has been expected to replace fusion surgery. A great deal of LTDR reports has come out. Among them, more than 5-year follow-up prospective randomized controlled studies including USA IDE trials were expected to elucidate whether for LTDR to have therapeutic benefit compared to fusion. The results of these studies revealed that LTDR was not inferior to fusion. Most of clinical studies dealing with LTDR revealed that there was no strong evidence for preventive effect of LTDR against symptomatic degenerative changes of adjacent segment disease. LTDR does not have shortcomings associated with fusion. However, it has a potentiality of the new complications to occur, which surgeons have never experienced in fusion surgeries. Consequently, longer follow-up should be necessary as yet to confirm the maintenance of improved surgical outcome and to observe any very late complications. LTDR still may get a chance to establish itself as a substitute of fusion both nominally and virtually if it eases the concerns listed above. PMID:26713139

  15. Clinical Features of Herniated Disc at Cervicothoracic Junction Level Treated by Anterior Approach

    PubMed Central

    Lee, Jun Gue; Kim, Hyeun Sung; Ju, Chang Il

    2016-01-01

    Objective The anterior approach for C7-T1 disc herniation may be challenging because of obstruction by the manubrium and the narrow operative field. This study aimed to investigate the clinical and neurological outcomes of anterior approach for C7-T1 disc herniation. Methods We retrospectively evaluated 13 patients who underwent the anterior approach for C7-T1 disc herniation by a single surgeon within a period of 11 years (2003-2014). The minimum follow-up duration was 6 months. We describe the clinical presentation, radiographic findings, neurological outcome, and related complications. Results Of 372 patients with single-level anterior discectomy and fusion or artificial disc replacement for cervical disc herniation, 13 (3.5%) had C7-T1 disc herniation. The main clinical presentation was unilateral motor weakness in intrinsic hand muscles (11 patients), along with numbness, pain, and tingling sensation that radiate down the arm to the little finger. Most of the patients improved after surgery via the anterior approach. Ten patients underwent successful anterior discectomy and fusion by the standard supramanubrial Smith-Robinson approach, but 2 needed additional manubriotomy and sternotomy. In 1 patient, we performed surgery at a wrong level because the correct level was difficult to identify intraoperatively. Two patients had transient vocal dysfunction, but none had major complications related to injuries of the great vessels such as the thoracic duct or esophagus. Conclusion For patients who require direct anterior decompression for C7-T1 disc herniation, the anterior approach is relatively feasible. However, care should be taken to overcome physical constraints by the manubrium and slope. PMID:27437013

  16. Artificial neural network modelling of the antioxidant activity and phenolic compounds of bananas submitted to different drying treatments.

    PubMed

    Guiné, Raquel P F; Barroca, Maria João; Gonçalves, Fernando J; Alves, Mariana; Oliveira, Solange; Mendes, Mateus

    2015-02-01

    Bananas (cv. Musa nana and Musa cavendishii) fresh and dried by hot air at 50 and 70°C and lyophilisation were analysed for phenolic contents and antioxidant activity. All samples were subject to six extractions (three with methanol followed by three with acetone/water solution). The experimental data served to train a neural network adequate to describe the experimental observations for both output variables studied: total phenols and antioxidant activity. The results show that both bananas are similar and air drying decreased total phenols and antioxidant activity for both temperatures, whereas lyophilisation decreased the phenolic content in a lesser extent. Neural network experiments showed that antioxidant activity and phenolic compounds can be predicted accurately from the input variables: banana variety, dryness state and type and order of extract. Drying state and extract order were found to have larger impact in the values of antioxidant activity and phenolic compounds. PMID:25172734

  17. Pharmacological mydriasis and optic disc examination

    PubMed Central

    Kirwan, J.; Gouws, P.; Linnell, A.; Crowston, J.; Bunce, C.

    2000-01-01

    AIM—To determine whether pharmacological mydriasis leads to a significant difference in interobserver agreement of optic disc measurement compared with examination without mydriasis.
METHOD—A cross sectional study was performed with a pair of observers examining the optic disc of two randomised groups of patients, one group before diagnostic mydriasis, and the other afterwards. Horizontal and vertical disc diameters and cup/disc ratios were measured with a 78 dioptre lens. The study was repeated with another observer pair and two further groups of patients.
RESULTS—In study A 86 subjects were examined in total (52 without and 34 with mydriasis). In study B 87 subjects were examined (45 without and 42 with mydriasis). The 95% limits of agreement of the cup/disc ratio measurement differences were significantly larger without mydriasis (p<0.001 for all studies (F test)). For both studies examination after mydriasis gave significantly greater agreement for vertical and horizontal cup/disc ratios. The cases with good agreement (0.1 difference or better) for vertical cup/disc ratios were 37/52 (72%) and 34 /45 (76%) without mydriasis and 33/34 (97%) and 40/42 (95%) respectively with mydriasis. Similar differences were recorded for horizontal cup/disc ratios. Disc diameter measurement results showed similar differences in study A but were not affected by mydriasis in study B.
CONCLUSIONS—Examination of the optic disc without pharmacological mydriasis gives significantly poorer interobserver agreement. In this study, the mean 95% limits of agreement values for all cup/disc ratio values were 0.27 for examination without mydriasis and 0.13 for examination with mydriasis. A measure outside these limits would suggest a real difference. This study indicates that mydriasis is important for reproducible clinical examination in glaucoma.

 PMID:10906099

  18. Quantitative Pfirrmann Disc Degeneration Grading System to Overcome the Limitation of Pfirrmann Disc Degeneration Grade

    PubMed Central

    2016-01-01

    Objective Pfirrmann disc degeneration grade is one of morphologic disc degeneration grading system and it was reliable on routine T2-weighted magnetic resonance (MR) images. The purpose of this study was to evaluate the agreement of Pfirrmann disc degeneration grade, and check the alternative technique of disc degeneration grading system. Methods Fifteen volunteers (4 medical doctors related to spinal disease, 2 medical doctors not related to spinal disease, 6 nurses in spinal hospital, and 3 para-medicines) were included in this study. Three different digitalized MR images were provided all volunteers, and they checked Pfirrmann disc degeneration grade of each disc levels after careful listening to explanation. Indeed, all volunteers checked the signal intensity of disc degeneration at the points of nucleus pulposus (NP), disc membrane, ligaments, fat, and air to modify the quantitative Pfirrmann disc degeneration grade. Results Total 225 grade results of Pfirrmann disc degeneration grade and 405 signal intensity results of quantitative Pfirrmann disc degeneration grade were analyzed. Average interobserver agreement was "moderate (mean±standard deviation, 0.575±0.251)" from poor to excellent. Completely agreed levels of Pfirrmann disc degeneration grade were only 4 levels (26.67%), and the disagreement levels were observed in 11 levels; two different grades in 8 levels (53.33%) and three different grades in 3 levels (20%). Quantitative Pfirrmann disc degeneration showed relatively cluster distribution with the interobserver deviations of 0.41-1.56 at the ratio of NP and disc membrane, and it showed relatively good cluster and distribution indicating that the proposed grading system has good discrimination ability. Conclusion Pfirrmann disc degeneration grade showed the limitation of different interobserver results, but this limitation could be overcome by using quantitative techniques of MR signal intensity. Further evaluation is needed to access its advantage

  19. Electronic and thermal lensing in diode end-pumped Yb:YAG laser rods and discs

    SciTech Connect

    Antipov, Oleg L; Anashkina, E A; Fedorova, K A

    2009-12-31

    The lensing effects in diode end-pumped Yb:YAG laser rods and discs are studied. Two mechanisms of refractive-index changes are taken into account, thermal and electronic (due to the difference between the excited- and ground-state Yb{sup 3+} polarisabilities), as well as pump-induced deformation of the laser crystal. Under pulsed pumping, the electronic lensing effect prevails over the thermal one in both rods and discs. In rods pumped by a highly focused cw beam, the dioptric power of the electronic lens exceeds that of the thermal lens, whereas in discs steady-state lensing is predominantly due to the thermal mechanism. (active media)

  20. Use NASA GES DISC Data in ArcGIS

    NASA Technical Reports Server (NTRS)

    Yang, Wenli; Pham, Long B.; Kempler, Steve

    2015-01-01

    This presentation describes GIS relevant data at NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), GES DISC Services and Support for GIS Users, and use cases of GES DISC data in ArcGIS.

  1. Immobilized Horseradish Peroxidase on Discs of Polyvinyl Alcohol-Glutaraldehyde Coated with Polyaniline

    PubMed Central

    Caramori, Samantha Salomão; Fernandes, Kátia Flávia; de Carvalho Junior, Luiz Bezerra

    2012-01-01

    Discs of network polyvinyl alcohol-glutaraldehyde (PVAG) were synthesized and coated with polyaniline (PANI) using glutaraldehyde as a chemical arm (PVAG-PANIG-HRP disc). The best conditions for the immobilization were established as about 1.0 mg mL−1 of protein, for 60 min and pH 5.5. The soluble enzyme lost all of its activity after incubation at 70°C for 15 min, whereas the PVAG-PANIG-HRP disc retained about half of the initial activity for pyrogallol. The same PVAG-PANIG-HRP disc was used consecutively three times without any activity lossbut presented 25% of the initial activity after the 7th use. PVAG-PANIG-HRP disc retained approximately 80% and 60% of its initial activity after 60 and 80 days of storage, respectively. Resorcinol, m-cresol, catechol, pyrogallol, α-naphthol, βnaphthol, and 4, 4′-diaminodiphenyl benzidine were efficiently oxidized by the PVAG-PANIG-HRP disc (from about 70% to 90%), and it was less efficient towards aniline, phenol, and 2-nitrosonaphthol. PMID:22619582

  2. Changes in disc herniation after CT-guided Percutaneous Laser Disc Decompression (PLDD): MR findings

    NASA Astrophysics Data System (ADS)

    Brat, Hugues G.; Bouziane, Tarik; Lambert, Jean; Divano, Luisa

    2004-09-01

    The aim of Percutaneous Laser Disc Decompression (PLDD) is to vaporize a small portion of the nucleus pulposus. Clinical efficacy of this technique is largely proven. However, time-evolution of intervertebral disc and its hernia after PLDD is not known. This study analyses changes in disc herniation and its native intervertebral disc at a mean follow-up of 7.5 months after PLDD in asymptomatic patients. Main observations at MRI are appearance of a high signal on T2WI in the hernia in 59%, shrinking of the hernia in 66% and overall stability of disc height.

  3. Rapid radiative clearing of protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Haworth, Thomas J.; Clarke, Cathie J.; Owen, James E.

    2016-04-01

    The lack of observed transition discs with inner gas holes of radii greater than ˜50 au implies that protoplanetary discs dispersed from the inside out must remove gas from the outer regions rapidly. We investigate the role of photoevaporation in the final clearing of gas from low mass discs with inner holes. In particular, we study the so-called `thermal sweeping' mechanism which results in rapid clearing of the disc. Thermal sweeping was originally thought to arise when the radial and vertical pressure scalelengths at the X-ray heated inner edge of the disc match. We demonstrate that this criterion is not fundamental. Rather, thermal sweeping occurs when the pressure maximum at the inner edge of the dust heated disc falls below the maximum possible pressure of X-ray heated gas (which depends on the local X-ray flux). We derive new critical peak volume and surface density estimates for rapid radiative clearing which, in general, result in rapid dispersal happening less readily than in previous estimates. This less efficient clearing of discs by X-ray driven thermal sweeping leaves open the issue of what mechanism (e.g. far-ultraviolet heating) can clear gas from the outer disc sufficiently quickly to explain the non-detection of cold gas around weak line T Tauri stars.

  4. The inner cavity of the circumnuclear disc

    NASA Astrophysics Data System (ADS)

    Blank, M.; Morris, M. R.; Frank, A.; Carroll-Nellenback, J. J.; Duschl, W. J.

    2016-06-01

    The circumnuclear disc (CND) orbiting the Galaxy's central black hole is a reservoir of material that can ultimately provide energy through accretion, or form stars in the presence of the black hole, as evidenced by the stellar cluster that is presently located at the CND's centre. In this paper, we report the results of a computational study of the dynamics of the CND. The results lead us to question two paradigms that are prevalent in previous research on the Galactic Centre. The first is that the disc's inner cavity is maintained by the interaction of the central stellar cluster's strong winds with the disc's inner rim, and secondly, that the presence of unstable clumps in the disc implies that the CND is a transient feature. Our simulations show that, in the absence of a magnetic field, the interaction of the wind with the inner disc rim actually leads to a filling of the inner cavity within a few orbital time-scales, contrary to previous expectations. However, including the effects of magnetic fields stabilizes the inner disc rim against rapid inward migration. Furthermore, this interaction causes instabilities that continuously create clumps that are individually unstable against tidal shearing. Thus the occurrence of such unstable clumps does not necessarily mean that the disc is itself a transient phenomenon. The next steps in this investigation are to explore the effect of the magnetorotational instability on the disc evolution and to test whether the results presented here persist for longer time-scales than those considered here.

  5. D-Zero Cryostat Supplemental Rupture Disc

    SciTech Connect

    Mulholland, G.T.; /Fermilab

    1987-08-03

    The common relief and rupture disc vent line requires a double disc assembly with vented interspace for accurate disc burst pressures. The first disc must take pump and purge vacuum loading, but be set to operate at 110% of the MAWP, 18.3 psig (ASME code). The available solution is 18.3 psig with a burst tolerance of +/- psig. The interspace should be locally vented by a flow limiting vent valve to decouple the vent line backpressure from the vessel rupture disc. The second disc must take the worst case vent line backpressure, the steady state value found in D-Zero engineering note 3740.000-EN-63 with all three cryostats simultaneously venting at the fire condition into the 4-inch x 6-inch and 6-inch x 8-inch sections. This value is less than 2 psid. The maximum rupture value for the second disc must be less than the minimum rupture value for the first disc less 2 psid i.e. < 16.3.

  6. Floquet analysis in accretion disc dynamics

    NASA Astrophysics Data System (ADS)

    Tamburini, F.; Bianchini, A.

    2002-01-01

    Floquet analysis is proposed to analyze the evolution of exponentially growing modes of the local instabilities in accretion discs of CVs induced by perturbations in the velocity field. Both the stability of the disc and the deviation of the Reynolds number are described by the Floquet exponents μj of the perturbations, which represent Landau's modes of the fluid.

  7. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  8. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  9. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  10. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  11. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  12. Simulations of the Galactic Centre Stellar Discs In a Warped Disc Origin Scenario

    NASA Astrophysics Data System (ADS)

    Ulubay-Siddiki, A.; Bartko, H.

    2012-07-01

    The Galactic Center (GC) hosts a population of young stars some of which seem to form a system of mutually inclined warped discs. While the presence of young stars in the close vicinity of the massive black hole is already problematic, their orbital configuration makes the situation even more puzzling. We present a possible warped disc origin scenario for these stars, which assumes an initially flat accretion disc which develops a warp through Pringle instability, or Bardeen-Petterson Effect. By working out the critical radii and the time scales involved, we argue that disc warping is plausible for GC parameters. We construct time evolution models for such discs considering the discs' self-gravity, and the torques exerted by the surrounding old star cluster. Our simulations suggest that the best agreement for a purely self-gravitating model is obtained for a disc-to-black hole mass ratio of Md/Mbh ~ 0.001.

  13. Dependence of optic disc parameters on disc area according to Heidelberg Retina Tomograph: Part II.

    NASA Astrophysics Data System (ADS)

    Machekhin, V.; Manaenkova, G.; Bondarenko, O.

    2007-05-01

    With the help of Heidelberg Retina Tomograph (HRT-II) optic disc parameters in 211 eyes of 115 healthy patients with refraction Em +/- 3,0 D and 96 eyes of 72 patients with myopia 3,5-14,0 D without any signs of glaucoma were studied. Analysis of optic disc parameters were carried out in 5 groups of patients according to disc area: less than 1,5 mm2, 1,5- 2,5 mm2, 2,5-3,0 mm2, 3,0-3,5 mm2 and more than 3,5 mm2. An accurate depending on disc area was revealed for all optic disc parameters in all sectors, which was manifested by increasing cup disc and rim disc (area and volume) and other parameters. We consider it is necessary to use the proper tables for right interpretation of received data for early diagnosis of glaucoma.

  14. High pressures and asymmetrical stresses in the scoliotic disc in the absence of muscle loading

    PubMed Central

    Meir, Adam R; Fairbank, Jeremy CT; Jones, Deborah A; McNally, Donal S; Urban, Jill PG

    2007-01-01

    Background Loads acting on scoliotic spines are thought to be asymmetric and involved in progression of the scoliotic deformity; abnormal loading patterns lead to changes in bone and disc cell activity and hence to vertebral body and disc wedging. At present however there are no direct measurements of intradiscal stresses or pressures in scoliotic spines. The aim of this study was to obtain quantitative measurements of the intradiscal stress environment in scoliotic intervertebral discs and to determine if loads acting across the scoliotic spine are asymmetric. We performed in vivo measurements of stresses across the intervertebral disc in patients with scoliosis, both parallel (termed horizontal) and perpendicular (termed vertical) to the end plate, using a side mounted pressure transducer (stress profilometry) Methods Stress profilometry was used to measure horizontal and vertical stresses at 5 mm intervals across 25 intervertebral discs of 7 scoliotic patients during anterior reconstructive surgery. A state of hydrostatic pressure was defined by identical horizontal and vertical stresses for at least two consecutive readings. Results were compared with similar stress profiles measured during surgery across 10 discs of 4 spines with no lateral curvature and with data from the literature. Results Profiles across scoliotic discs were very different from those of normal, young, healthy discs of equivalent age previously presented in the literature. Hydrostatic pressure regions were only seen in 14/25 discs, extended only over a short distance. Non-scoliotic discs of equivalent age would be expected to show large centrally placed hydrostatic nuclear regions in all discs. Mean pressures were significantly greater (0.25 MPa) than those measured in other anaesthetised patients (<0.07 MPa). A stress peak was seen in the concave annulus in 13/25 discs. Stresses in the concave annulus were greater than in the convex annulus indicating asymmetric loading in these

  15. About detection of precessing circumpulsar discs

    NASA Astrophysics Data System (ADS)

    Grimani, Catia

    2016-08-01

    Detections of circumpulsar discs and planetary systems through electromagnetic observations appear quite rare. In the case of PSR 1931+24 and B0656+14, the hypothesis of a precessing disc penetrating the pulsar light cylinder is found consistent with radio and gamma observations from these stars. Disc self-occultation and precession may affect electromagnetic measurements. We investigate here under which conditions gravitational waves generated by circumpulsar disc precession may be detected by the proposed second-generation space interferometers DECI-hertz Interferometer Gravitational Wave Observatory and Big Bang Observer. The characteristics of circumpulsar detectable precessing discs are estimated as a function of distance from the Solar system. Speculations on detection rates are presented.

  16. Strongly magnetized accretion discs require poloidal flux

    NASA Astrophysics Data System (ADS)

    Salvesen, Greg; Armitage, Philip J.; Simon, Jacob B.; Begelman, Mitchell C.

    2016-08-01

    Motivated by indirect observational evidence for strongly magnetized accretion discs around black holes, and the novel theoretical properties of such solutions, we investigate how a strong magnetization state can develop and persist. To this end, we perform local simulations of accretion discs with an initially purely toroidal magnetic field of equipartition strength. We demonstrate that discs with zero net vertical magnetic flux and realistic boundary conditions cannot sustain a strong toroidal field. However, a magnetic pressure-dominated disc can form from an initial configuration with a sufficient amount of net vertical flux and realistic boundary conditions. Our results suggest that poloidal flux is a necessary prerequisite for the sustainability of strongly magnetized accretion discs.

  17. Lumbar Epidural Varix Mimicking Disc Herniation

    PubMed Central

    Bursalı, Adem; Guvenal, Ahmet Burak; Yaman, Onur

    2016-01-01

    Lumbar radiculopathy is generally caused by such well-recognized entity as lumbar disc herniation in neurosurgical practice; however rare pathologies such as thrombosed epidural varix may mimic them by causing radicular symptoms. In this case report, we present a 26-year-old man with the complaint of back and right leg pain who was operated for right L4–5 disc herniation. The lesion interpreted as an extruded disc herniation preoperatively was found to be a thrombosed epidural varix compressing the nerve root preoperatively. The nerve root was decompressed by shrinking the lesion with bipolar thermocoagulation and excision. The patient's complaints disappeared in the postoperative period. Thrombosed lumbar epidural varices may mimic lumbar disc herniations both radiologically and clinically. Therefore, must be kept in mind in the differential diagnosis of lumbar disc herniations. Microsurgical techniques are mandatory for the treatment of these pathologies and decompression with thermocoagulation and excision is an efficient method. PMID:27446525

  18. Lumbar Epidural Varix Mimicking Disc Herniation.

    PubMed

    Bursalı, Adem; Akyoldas, Goktug; Guvenal, Ahmet Burak; Yaman, Onur

    2016-07-01

    Lumbar radiculopathy is generally caused by such well-recognized entity as lumbar disc herniation in neurosurgical practice; however rare pathologies such as thrombosed epidural varix may mimic them by causing radicular symptoms. In this case report, we present a 26-year-old man with the complaint of back and right leg pain who was operated for right L4-5 disc herniation. The lesion interpreted as an extruded disc herniation preoperatively was found to be a thrombosed epidural varix compressing the nerve root preoperatively. The nerve root was decompressed by shrinking the lesion with bipolar thermocoagulation and excision. The patient's complaints disappeared in the postoperative period. Thrombosed lumbar epidural varices may mimic lumbar disc herniations both radiologically and clinically. Therefore, must be kept in mind in the differential diagnosis of lumbar disc herniations. Microsurgical techniques are mandatory for the treatment of these pathologies and decompression with thermocoagulation and excision is an efficient method. PMID:27446525

  19. Strongly magnetized accretion discs require poloidal flux

    NASA Astrophysics Data System (ADS)

    Salvesen, Greg; Armitage, Philip J.; Simon, Jacob B.; Begelman, Mitchell C.

    2016-05-01

    Motivated by indirect observational evidence for strongly magnetized accretion discs around black holes, and the novel theoretical properties of such solutions, we investigate how a strong magnetization state can develop and persist. To this end, we perform local simulations of accretion discs with an initially purely toroidal magnetic field of equipartition strength. We demonstrate that discs with zero net vertical magnetic flux and realistic boundary conditions cannot sustain a strong toroidal field. However, a magnetic pressure-dominated disc can form from an initial configuration with a sufficient amount of net vertical flux and realistic boundary conditions. Our results suggest that poloidal flux is a necessary prerequisite for the sustainability of strongly magnetized accretion discs.

  20. During Drosophila disc regeneration, JAK/STAT coordinates cell proliferation with Dilp8-mediated developmental delay.

    PubMed

    Katsuyama, Tomonori; Comoglio, Federico; Seimiya, Makiko; Cabuy, Erik; Paro, Renato

    2015-05-01

    Regeneration of fragmented Drosophila imaginal discs occurs in an epimorphic manner involving local cell proliferation at the wound site. After disc fragmentation, cells at the wound site activate a restoration program through wound healing, regenerative cell proliferation, and repatterning of the tissue. However, the interplay of signaling cascades driving these early reprogramming steps is not well-understood. Here, we profiled the transcriptome of regenerating cells in the early phase within 24 h after wounding. We found that JAK/STAT signaling becomes activated at the wound site and promotes regenerative cell proliferation in cooperation with Wingless (Wg) signaling. In addition, we showed that the expression of Drosophila insulin-like peptide 8 (dilp8), which encodes a paracrine peptide to delay the onset of pupariation, is controlled by JAK/STAT signaling in early regenerating discs. Our findings suggest that JAK/STAT signaling plays a pivotal role in coordinating regenerative disc growth with organismal developmental timing. PMID:25902518

  1. Spine imaging after lumbar disc replacement: pitfalls and current recommendations

    PubMed Central

    Robinson, Yohan; Sandén, Bengt

    2009-01-01

    Background Most lumbar artificial discs are still composed of stainless steel alloys, which prevents adequate postoperative diagnostic imaging of the operated region when using magnetic resonance imaging (MRI). Thus patients with postoperative radicular symptoms or claudication after stainless steel implants often require alternative diagnostic procedures. Methods Possible complications of lumbar total disc replacement (TDR) are reviewed from the available literature and imaging recommendations given with regard to implant type. Two illustrative cases are presented in figures. Results Access-related complications, infections, implant wear, loosening or fracture, polyethylene inlay dislodgement, facet joint hypertrophy, central stenosis, and ankylosis of the operated segment can be visualised both in titanium and stainless steel implants, but require different imaging modalities due to magnetic artifacts in MRI. Conclusion Alternative radiographic procedures should be considered when evaluating patients following TDR. Postoperative complications following lumbar TDR including spinal stenosis causing radiculopathy and implant loosening can be visualised by myelography and radionucleotide techniques as an adjunct to plain film radiographs. Even in the presence of massive stainless steel TDR implants lumbar radicular stenosis and implant loosening can be visualised if myelography and radionuclide techniques are applied. PMID:19619332

  2. Galaxies that shine: radiation-hydrodynamical simulations of disc galaxies

    NASA Astrophysics Data System (ADS)

    Rosdahl, Joakim; Schaye, Joop; Teyssier, Romain; Agertz, Oscar

    2015-07-01

    Radiation feedback is typically implemented using subgrid recipes in hydrodynamical simulations of galaxies. Very little work has so far been performed using radiation-hydrodynamics (RHD), and there is no consensus on the importance of radiation feedback in galaxy evolution. We present RHD simulations of isolated galaxy discs of different masses with a resolution of 18 pc. Besides accounting for supernova feedback, our simulations are the first galaxy-scale simulations to include RHD treatments of photoionization heating and radiation pressure, from both direct optical/UV radiation and multiscattered, re-processed infrared (IR) radiation. Photoheating smooths and thickens the discs and suppresses star formation about as much as the inclusion of (`thermal dump') supernova feedback does. These effects decrease with galaxy mass and are mainly due to the prevention of the formation of dense clouds, as opposed to their destruction. Radiation pressure, whether from direct or IR radiation, has little effect, but for the IR radiation we show that its impact is limited by our inability to resolve the high optical depths for which multiscattering becomes important. While artificially boosting the IR optical depths does reduce the star formation, it does so by smoothing the gas rather than by generating stronger outflows. We conclude that although higher resolution simulations, and potentially also different supernova implementations, are needed for confirmation, our findings suggest that radiation feedback is more gentle and less effective than is often assumed in subgrid prescriptions.

  3. The Role of Physical Viscosity in Accretion Disc Dynamics in Close Binaries and AGN

    NASA Astrophysics Data System (ADS)

    Lanzafame, G.

    2008-04-01

    The role of turbulent physical viscosity is here considered as far as an accretion disc is concerned both in close binaries (CB) and around massive black holes in active galactic nuclei (AGN). The study has been performed via SPH simulations of disc models. Physical viscosity has been considered according to the Shakura and Sunjaev α prescription. Results show that physical viscosity supports and favours accretion disc formation in low compressibility models. Spiral shocks in the radial flux develop only in some high compressibility models. Physical viscosity efficiently supports mass, angular momentum and heat radial transport towards the compact primary star as well as the radial disc spread. Results show that compressibility-viscosity domains exist, where turbulent physical viscosity supports the accretion disc formation. A role also played by the injection kinematics at the inner Lagrangian point L1 is also found. A grid of physically viscous 3D SPH, axially symmetric, accretion disc simulations around black holes (BH) in AGN, have also been performed, paying also attention to the role of the specific angular momentum λ as an initial boundary condition at the disc outer edge. A shock front usually develops, according to assigned outer edge initial and boundary conditions, mainly due to the centrifugal barrier. Pairs of (λ, α) values exist, determining radial periodical oscillations in the shock front. Periodical outflows can develop from the subsonic post shock region close to the BH in some cases.

  4. Structure and evolutionary history of DISC1.

    PubMed

    Sanchez-Pulido, Luis; Ponting, Chris P

    2011-10-15

    Evolutionary and protein structural analyses can provide functional insights into genes implicated in human psychiatric diseases. Even eukaryotic organisms lacking nervous systems contain homologues of many key signalling molecules of animal neurons implying that human cognition derives, in part, from modifications of ancestral molecules and complexes. One protein whose evolutionary origin is obscure is DISC1 (disrupted in schizophrenia 1) whose gene locus has been associated with many psychiatric conditions including schizophrenia, clinical depression and bipolar disorder. This protein's rapid evolution and its unusual amino acid and α-helix composition have hindered searches for DISC1 homologues in species other than vertebrates. Here, we review the evolution and structure of the DISC1 protein in the light of in-depth sequence analyses. These predict DISC1 orthologues in diverse eukaryotic organisms, including early-branching animals such as amphioxus, sea anemone, amoebas and Trichoplax, and in plants and algae. DISC1 thus is widespread among eukaryotes, although it remains absent from fungi, nematodes and Diptera, including fruit flies. These observations now permit studies of DISC1 function in simple non-vertebrate model organisms. Surprisingly, these analyses also identify between two and four sequence repeats in DISC1 orthologues. The first two of these repeats show significant sequence similarity to the UVR family of globular domains. These UVR-like repeats are predicted to contain, not coiled coil structures, but rather two closely associated antiparallel α-helices. One common missense variant in DISC1 (L607F) lies within the second DISC1 UVR-like domain. These observations should assist in delineating the functional regions of the DISC1 protein. PMID:21852244

  5. Inflatable artificial sphincter

    MedlinePlus

    ... works well. When you need to urinate, the cuff of the artificial sphincter can be relaxed so ... pain. An artificial sphincter has three parts: A cuff, which fits around your urethra, the tube that ...

  6. Creation of a tablet database containing several active ingredients and prediction of their pharmaceutical characteristics based on ensemble artificial neural networks.

    PubMed

    Takagaki, Keisuke; Arai, Hiroaki; Takayama, Kozo

    2010-10-01

    A tablet database containing several active ingredients for a standard tablet formulation was created. Tablet tensile strength (TS) and disintegration time (DT) were measured before and after storage for 30 days at 40 degrees C and 75% relative humidity. An ensemble artificial neural network (EANN) was used to predict responses to differences in quantities of excipients and physical-chemical properties of active ingredients in tablets. Most classical neural networks involve a tedious trial and error approach, but EANNs automatically determine basal key parameters, which ensure that an optimal structure is rapidly obtained. We compared the predictive abilities of EANNs in which the following kinds of training algorithms were used: linear, radial basis function, general regression (GR), and multilayer perceptron. The GR EANN predicted pharmaceutical responses such as TS and DT most accurately, as evidenced by high correlation coefficients in a leave-some-out cross-validation procedure. When used in conjunction with a tablet database, the GR EANN is capable of identifying acceptable candidate tablet formulations. PMID:20310024

  7. Modified high-density lipoproteins by artificial sweetener, aspartame, and saccharin, showed loss of anti-atherosclerotic activity and toxicity in zebrafish.

    PubMed

    Kim, Jae-Yong; Park, Ki-Hoon; Kim, Jihoe; Choi, Inho; Cho, Kyung-Hyun

    2015-01-01

    Safety concerns have been raised regarding the association of chronic consumption of artificial sweeteners (ASs) with metabolic disorders, especially in the heart and brain. There has been no information on the in vivo physiological effects of AS consumption in lipoprotein metabolism. High-dosage treatment (final 25, 50, and 100 mM) with AS (aspartame, acesulfame K, and saccharin) to human high-density lipoprotein (HDL) induced loss of antioxidant ability along with elevated atherogenic effects. Aspartame-treated HDL3 (final 100 mM) almost all disappeared due to putative proteolytic degradation. Aspartame- and saccharin-treated HDL3 showed more enhanced cholesteryl ester transfer activity, while their antioxidant ability was disappeared. Microinjection of the modified HDL3 exacerbated the inflammatory death in zebrafish embryos in the presence of oxLDL. These results show that AS treatment impaired the beneficial functions of HDL, resulting in loss of antioxidant and anti-atherogenic activities. These results suggest that aspartame and saccharin could be toxic to the human circulation system as well as embryonic development via impairment of lipoprotein function. PMID:25142179

  8. Biomechanical Analysis of a Novel Prosthesis Based on the Physiological Curvature of Endplate for Cervical Disc Replacement

    PubMed Central

    Yu, Cheng-Cheng; Hao, Ding-Jun; Huang, Da-Geng; Qian, Li-Xiong; Feng, Hang; Li, Hou-Kun; Zhao, Song-Chuan

    2016-01-01

    Study Design Biomechanical analysis of a novel prosthesis based on the physiological curvature of endplate was performed. Objective To compare the biomechanical differences between a novel prosthesis based on the physiological curvature of the endplate and the Prestige LP prosthesis after cervical disc replacement (CDR). Summary of Background Data Artificial disc prostheses have been widely used to preserve the physiological function of treated and adjacent motion segments in CDR, while most of those present a flat surface instead of an arcuate surface which approximately similar to anatomic structures in vivo. We first reported a well-designed artificial disc prosthesis based on the physiological curvature of the endplate. Methods Three motion segments of 24 ovine cervical spines (C2-5) were evaluated in a robotic spine system with axial compressive loads of 50N. Testing conditions were as follows: 1) intact, 2) C3–4 CDR with artificial disc prosthesis based on the physiological curvature of the endplate, and 3) C3–4 CDR with the Prestige LP prosthesis. The range of motion (ROM) and the pressures on the inferior surface of the two prostheses were recorded and analyzed. Results As compared to the intact state, the ROM of all three segments had no significant difference in the replacement group. Additionally, there was no significant difference in ROM between the two prostheses. The mean pressure on the novel prosthesis was significantly less than the Prestige LP prosthesis. Conclusion ROM in 3 groups (intact group, CDR group with novel prosthesis and CDR group with Prestige LP) showed no significant difference. The mean pressure on the inferior surface of the novel prosthesis was significantly lower than the Prestige LP prosthesis. Therefore, the novel artificial disc prosthesis is feasible and effective, and can reduce the implant-bone interface pressure on the endplate, which may be one possible reason of prosthesis subsidence. PMID:27355319

  9. Artificial Video for Video Analysis

    ERIC Educational Resources Information Center

    Gallis, Michael R.

    2010-01-01

    This paper discusses the use of video analysis software and computer-generated animations for student activities. The use of artificial video affords the opportunity for students to study phenomena for which a real video may not be easy or even possible to procure, using analysis software with which the students are already familiar. We will…

  10. Influence of unilateral disc displacement on the stress response of the temporomandibular joint discs during opening and mastication

    PubMed Central

    Pérez del Palomar, A; Doblaré, M

    2007-01-01

    The temporomandibular joint plays a crucial role in human mastication acting as a guide of jaw movements. During these movements, the joint is subjected to loads which cause stresses and deformations in its cartilaginous structures. A perfect balance between the two sides of the joint is essential to maintain the physiological stress level within the tissues. Therefore, it has been suggested that a derangement of the joint is a contributing factor in the development of mandibular asymmetry, especially if problems of the temporomandibular joint start in childhood or adolescence. To analyze the movement of the mandible and the stresses undergone by the discs, two finite element models of the human temporomandibular joint including the masticatory system were developed, one corresponding to a healthy joint and the other with a unilateral anterior disc displacement with their movement controlled by muscle activation. A fibre-reinforced porohyperelastic model was used to simulate the behaviour of the articular discs. The stress distribution was analyzed in both models during free opening and closing, and during the introduction of a resistant force between incisors or molars. It was found that a slight unilateral anterior disc displacement does not lead to mandibular asymmetry but to a slight decrease of the maximum gape. With the introduction of a restriction between incisors, the maximum stresses moved to the anterior band in contrast to what happened if the restriction was imposed between molars where maximum stresses were located more posteriorly. Finally, the presence of a unilateral displacement of the disc involved a strong change in the overall behaviour of the joint including also the healthy side, where the maximum stresses moved to the posterior part. PMID:17725577

  11. The effects of high-frequency oscillations in hippocampal electrical activities on the classification of epileptiform events using artificial neural networks

    NASA Astrophysics Data System (ADS)

    Chiu, Alan W. L.; Jahromi, Shokrollah S.; Khosravani, Houman; Carlen, Peter L.; Bardakjian, Berj L.

    2006-03-01

    The existence of hippocampal high-frequency electrical activities (greater than 100 Hz) during the progression of seizure episodes in both human and animal experimental models of epilepsy has been well documented (Bragin A, Engel J, Wilson C L, Fried I and Buzsáki G 1999 Hippocampus 9 137-42 Khosravani H, Pinnegar C R, Mitchell J R, Bardakjian B L, Federico P and Carlen P L 2005 Epilepsia 46 1-10). However, this information has not been studied between successive seizure episodes or utilized in the application of seizure classification. In this study, we examine the dynamical changes of an in vitro low Mg2+ rat hippocampal slice model of epilepsy at different frequency bands using wavelet transforms and artificial neural networks. By dividing the time-frequency spectrum of each seizure-like event (SLE) into frequency bins, we can analyze their burst-to-burst variations within individual SLEs as well as between successive SLE episodes. Wavelet energy and wavelet entropy are estimated for intracellular and extracellular electrical recordings using sufficiently high sampling rates (10 kHz). We demonstrate that the activities of high-frequency oscillations in the 100-400 Hz range increase as the slice approaches SLE onsets and in later episodes of SLEs. Utilizing the time-dependent relationship between different frequency bands, we can achieve frequency-dependent state classification. We demonstrate that activities in the frequency range 100-400 Hz are critical for the accurate classification of the different states of electrographic seizure-like episodes (containing interictal, preictal and ictal states) in brain slices undergoing recurrent spontaneous SLEs. While preictal activities can be classified with an average accuracy of 77.4 ± 6.7% utilizing the frequency spectrum in the range 0-400 Hz, we can also achieve a similar level of accuracy by using a nonlinear relationship between 100-400 Hz and <4 Hz frequency bands only.

  12. In vivo Loads in the Lumbar L3-4 Disc during a Weight Lifting Extension

    PubMed Central

    Wang, Shaobai; Park, Won Man; Kim, Yoon Hyuk; Cha, Thomas; Wood, Kirkham; Li, Guoan

    2014-01-01

    Background Knowledge of in vivo human lumbar loading is critical for understanding the lumbar function and for improving surgical treatments of lumbar pathology. Although numerous experimental measurements and computational simulations have been reported, non-invasive determination of in vivo spinal disc loads is still a challenge in biomedical engineering. The object of the study is to investigate the in vivo human lumbar disc loads using a subject-specific and kinematic driven finite element approach. Methods Three dimensional (3D) lumbar spine models of three living subjects were created using MR images. A 3D finite element model of the L3-4 disc, including the annulus fibrosus and nucleus pulposus, was built for each subject. The endplate kinematics of the L3-4 segment of each subject during a dynamic weight lifting extension was determined using a dual fluoroscopic imaging technique. The endplate kinematics was used as displacement boundary conditions of the subject specific finite element model of the L3-4 disc to calculate the in-vivo disc forces and moments during the weight lifting activity. Findings During the weight lifting extension, the L3-4 disc experienced maximum shear load of about 230 N or 0.34 bodyweight at the flexion position and maximum compressive load of 1500 N or 2.28 bodyweight at the upright position. The disc experienced a primary flexion-extension moment during the motion which reached a maximum of 4.2 Nm at upright position with stretched arms holding the weight. Interpretation This study provided quantitative data on in vivo disc loading that could help understand intrinsic biomechanics of the spine and improve surgical treatment of pathological discs using fusion or arthroplasty techniques. PMID:24345591

  13. Stirring in massive, young debris discs from spatially resolved Herschel images

    NASA Astrophysics Data System (ADS)

    Moór, A.; Kóspál, Á.; Ábrahám, P.; Apai, D.; Balog, Z.; Grady, C.; Henning, Th.; Juhász, A.; Kiss, Cs.; Krivov, A. V.; Pawellek, N.; Szabó, Gy. M.

    2015-02-01

    A significant fraction of main-sequence stars are encircled by dusty debris discs, where the short-lived dust particles are replenished through collisions between planetesimals. Most destructive collisions occur when the orbits of smaller bodies are dynamically stirred up, either by the gravitational effect of locally formed Pluto-sized planetesimals (self-stirring scenario), or via secular perturbation caused by an inner giant planet (planetary stirring). The relative importance of these scenarios in debris systems is unknown. Here, we present new Herschel Space Observatory imagery of 11 discs selected from the most massive and extended known debris systems. All discs were found to be extended at far-infrared wavelengths, five of them being resolved for the first time. We evaluated the feasibility of the self-stirring scenario by comparing the measured disc sizes with the predictions of the model calculated for the ages of our targets. We concluded that the self-stirring explanation works for seven discs. However, in four cases, the predicted pace of outward propagation of the stirring front, assuming reasonable initial disc masses, was far too low to explain the radial extent of the cold dust. Therefore, for HD 9672, HD 16743, HD 21997, and HD 95086, another explanation is needed. We performed a similar analysis for β Pic and HR 8799, reaching the same conclusion. We argue that planetary stirring is a promising possibility to explain the disc properties in these systems. In HR 8799 and HD 95086, we may already know the potential perturber, since their known outer giant planets could be responsible for the stirring process. Interestingly, the discs around HD 9672, HD 21997, and β Pic are also unique in harbouring detectable amount of molecular CO gas. Our study demonstrates that among the largest and most massive debris discs self-stirring may not be the only active scenario, and potentially planetary stirring is responsible for destructive collisions and debris

  14. Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level.

    PubMed

    Hakan, Tayfun; Gürcan, Serkan

    2016-01-01

    Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain due to disc herniation caudally immigrating at L4-5 level three years ago. He refused the surgical intervention that was offered and was treated conservatively at that time. He had no neurological deficit and a history of spontaneous regression of the extruded lumbar disc; so, a conservative therapy, including bed rest, physical therapy, nonsteroidal anti-inflammatory drugs, and analgesics, was advised. In conclusion, herniated lumbar disc fragments may regress spontaneously. Reports are prone to advise conservative treatment for extruded or sequestrated lumbar disc herniations. However, these patients should be followed up closely; new herniation at adjacent/different level may occur. Furthermore, it is important to know which herniated disk should be removed and which should be treated conservatively, because disc herniation may cause serious complications as muscle weakness and cauda equine syndrome. PMID:27429818

  15. Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level

    PubMed Central

    Gürcan, Serkan

    2016-01-01

    Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain due to disc herniation caudally immigrating at L4-5 level three years ago. He refused the surgical intervention that was offered and was treated conservatively at that time. He had no neurological deficit and a history of spontaneous regression of the extruded lumbar disc; so, a conservative therapy, including bed rest, physical therapy, nonsteroidal anti-inflammatory drugs, and analgesics, was advised. In conclusion, herniated lumbar disc fragments may regress spontaneously. Reports are prone to advise conservative treatment for extruded or sequestrated lumbar disc herniations. However, these patients should be followed up closely; new herniation at adjacent/different level may occur. Furthermore, it is important to know which herniated disk should be removed and which should be treated conservatively, because disc herniation may cause serious complications as muscle weakness and cauda equine syndrome. PMID:27429818

  16. Stem cells sources for intervertebral disc regeneration

    PubMed Central

    Vadalà, Gianluca; Russo, Fabrizio; Ambrosio, Luca; Loppini, Mattia; Denaro, Vincenzo

    2016-01-01

    Intervertebral disc regeneration field is rapidly growing since disc disorders represent a major health problem in industrialized countries with very few possible treatments. Indeed, current available therapies are symptomatic, and surgical procedures consist in disc removal and spinal fusion, which is not immune to regardable concerns about possible comorbidities, cost-effectiveness, secondary risks and long-lasting outcomes. This review paper aims to share recent advances in stem cell therapy for the treatment of intervertebral disc degeneration. In literature the potential use of different adult stem cells for intervertebral disc regeneration has already been reported. Bone marrow mesenchymal stromal/stem cells, adipose tissue derived stem cells, synovial stem cells, muscle-derived stem cells, olfactory neural stem cells, induced pluripotent stem cells, hematopoietic stem cells, disc stem cells, and embryonic stem cells have been studied for this purpose either in vitro or in vivo. Moreover, several engineered carriers (e.g., hydrogels), characterized by full biocompatibility and prompt biodegradation, have been designed and combined with different stem cell types in order to optimize the local and controlled delivery of cellular substrates in situ. The paper overviews the literature discussing the current status of our knowledge of the different stem cells types used as a cell-based therapy for disc regeneration. PMID:27247704

  17. Stem cells sources for intervertebral disc regeneration.

    PubMed

    Vadalà, Gianluca; Russo, Fabrizio; Ambrosio, Luca; Loppini, Mattia; Denaro, Vincenzo

    2016-05-26

    Intervertebral disc regeneration field is rapidly growing since disc disorders represent a major health problem in industrialized countries with very few possible treatments. Indeed, current available therapies are symptomatic, and surgical procedures consist in disc removal and spinal fusion, which is not immune to regardable concerns about possible comorbidities, cost-effectiveness, secondary risks and long-lasting outcomes. This review paper aims to share recent advances in stem cell therapy for the treatment of intervertebral disc degeneration. In literature the potential use of different adult stem cells for intervertebral disc regeneration has already been reported. Bone marrow mesenchymal stromal/stem cells, adipose tissue derived stem cells, synovial stem cells, muscle-derived stem cells, olfactory neural stem cells, induced pluripotent stem cells, hematopoietic stem cells, disc stem cells, and embryonic stem cells have been studied for this purpose either in vitro or in vivo. Moreover, several engineered carriers (e.g., hydrogels), characterized by full biocompatibility and prompt biodegradation, have been designed and combined with different stem cell types in order to optimize the local and controlled delivery of cellular substrates in situ. The paper overviews the literature discussing the current status of our knowledge of the different stem cells types used as a cell-based therapy for disc regeneration. PMID:27247704

  18. Shear Mechanics of the TMJ Disc

    PubMed Central

    Juran, C.M.; Dolwick, M.F.; McFetridge, P.S.

    2012-01-01

    The temporomandibular joint (TMJ) is a complex hinge and gliding joint that induces significant shear loads onto the fibrocartilage TMJ disc during jaw motion. The purpose of this study was to assess regional variation in the disc’s shear loading characteristics under physiologically relevant loads and to associate those mechanical findings with common clinical observations of disc fatigue and damage. Porcine TMJ discs were compressed between an axially translating bottom platen and a 2.5-cm-diameter indenter within a hydrated testing chamber. Discs were cyclically sheared at 0.5, 1, or 5 Hz to 1, 3, or 5% shear strain. Within the anterior and intermediate regions of the disc when sheared in the anteroposterior direction, both shear and compressive moduli experienced a significant decrease from instantaneous to steady state, while the posterior region’s compressive modulus decreased approximately 5%, and no significant loss of shear modulus was noted. All regions retained their shear modulus within 0.5% of instantaneous values when shear was applied in the mediolateral direction. The results of the disc’s regional shear mechanics suggest an observable and predictable link with the common clinical observation that the posterior region of the disc is most often the zone in which fatigue occurs, which may lead to disc damage and perforation. PMID:23166043

  19. Transcript Profiling of Paoenia ostii during Artificial Chilling Induced Dormancy Release Identifies Activation of GA Pathway and Carbohydrate Metabolism

    PubMed Central

    Liu, Chunying; Zhang, Yang; Zheng, Guosheng

    2013-01-01

    Endo-dormant flower buds must pass through a period of chilling to reinitiate growth and subsequent flowering, which is a major obstacle to the forcing culture of tree peony in winter. Customized cDNA microarray (8×15 K element) was used to investigate gene expression profiling in tree peony ‘Feng Dan Bai’ buds during 24 d chilling treatment at 0–4°C. According to the morphological changes after the whole plants were transferred to green house, endo-dormancy was released after 18 d chilling treatment, and prolonged chilling treatment increased bud break rate. Pearson correlation hierarchical clustering of sample groups was highly consistent with the dormancy transitions revealed by morphological changes. Totally 3,174 significantly differentially-expressed genes (P<0.05) were observed through endo-dormancy release process, of which the number of up-regulated (1,611) and that of down-regulated (1,563) was almost the same. Functional annotation of differentially-expressed genes revealed that cellular process, metabolic process, response to stimulus, regulation of biological process and development process were well-represented. Hierarchical clustering indicated that activation of genes involved in carbohydrate metabolism (Glycolysis, Citrate cycle and Pentose phosphate pathway), energy metabolism and cell growth. Based on the results of GO analysis, totally 51 probes presented in the microarray were associated with GA response and GA signaling pathway, and 22 of them were differently expressed. The expression profiles also revealed that the genes of GA biosynthesis, signaling and response involved in endo-dormancy release. We hypothesized that activation of GA pathway played a central role in the regulation of dormancy release in tree peony. PMID:23405132

  20. Electron beam recording of optical disc

    NASA Astrophysics Data System (ADS)

    Cartwright, Giles; Reynolds, Gerald; Baylis, Chris; Pearce, Adrian; Dix, Colin; Ogilvie, Nick

    2002-09-01

    The Nimbus Technology & Engineering e -Beam Mastering System was developed to gain a large improvement in optical disc and structured hard disc recording capacity, significantly more than is possible from deep UV and SIL mastering. The current electron beam recorder is essentially a production machine capable of making full-length exposures at capacities of up to 50 GB with a simple low-cost upgrade path to disc capacities of several hundred gigabytes and beyond and hard disk drives (HDD) with capacities of up to 1 tera bit per square inch.

  1. [Lumbar disc herniation and andrological diseases].

    PubMed

    Jin, Bao-fang

    2015-10-01

    Lumbar disc herniation is a common male disease. In the past, More academic attention was directed to its relationship with lumbago and leg pain than to its association with andrological diseases. Studies show that central lumber intervertebral disc herniation may cause cauda equina injury and result in premature ejaculation, erectile dysfunction, chronic pelvic pain syndrome, priapism, and emission. This article presents an overview on the correlation between central lumbar intervertebral disc herniation and andrological diseases, focusing on the aspects of etiology, pathology, and clinical progress, hoping to invite more attention from andrological and osteological clinicians. PMID:26665671

  2. Spectroscopic Parameters of Lumbar Intervertebral Disc Material

    NASA Astrophysics Data System (ADS)

    Terbetas, G.; Kozlovskaja, A.; Varanius, D.; Graziene, V.; Vaitkus, J.; Vaitkuviene, A.

    2009-06-01

    There are numerous methods of investigating intervertebral disc. Visualization methods are widely used in clinical practice. Histological, imunohistochemical and biochemical methods are more used in scientific research. We propose that a new spectroscopic investigation would be useful in determining intervertebral disc material, especially when no histological specimens are available. Purpose: to determine spectroscopic parameters of intervertebral disc material; to determine emission spectra common for all intervertebral discs; to create a background for further spectroscopic investigation where no histological specimen will be available. Material and Methods: 20 patients, 68 frozen sections of 20 μm thickness from operatively removed intervertebral disc hernia were excited by Nd:YAG microlaser STA-01-TH third harmonic 355 nm light throw 0, 1 mm fiber. Spectrophotometer OceanOptics USB2000 was used for spectra collection. Mathematical analysis of spectra was performed by ORIGIN multiple Gaussian peaks analysis. Results: In each specimen of disc hernia were found distinct maximal spectral peaks of 4 types supporting the histological evaluation of mixture content of the hernia. Fluorescence in the spectral regions 370-700 nm was detected in the disc hernias. The main spectral component was at 494 nm and the contribution of the components with the peak wavelength values at 388 nm, 412 nm and 435±5 nm were varying in the different groups of samples. In comparison to average spectrum of all cases, there are 4 groups of different spectral signatures in the region 400-500 nm in the patient groups, supporting a clinical data on different clinical features of the patients. Discussion and Conclusion: besides the classical open discectomy, new minimally invasive techniques of treating intervertebral disc emerge (PLDD). Intervertebral disc in these techniques is assessed by needle, no histological specimen is taken. Spectroscopic investigation via fiber optics through the

  3. How Does Lumbar Degenerative Disc Disease Affect the Disc Deformation at the Cephalic Levels In Vivo?

    PubMed Central

    Wang, Shaobai; Xia, Qun; Passias, Peter; Li, Weishi; Wood, Kirkham; Li, Guoan

    2013-01-01

    Study Design Case-control study. Objective . To evaluate the effect of lumbar degenerative disc disease (DDD) on the disc deformation at the adjacent level and at the level one above the adjacent level during end ranges of lumbar motion. Summary of Background Data It has been reported that in patients with DDD, the intervertebral discs adjacent to the diseased levels have a greater tendency to degenerate. Although altered biomechanics have been suggested to be the causative factors, few data have been reported on the deformation characteristics of the adjacent discs in patients with DDD. Methods Ten symptomatic patients with discogenic low back pain between L4 and S1 and with healthy discs at the cephalic segments were involved. Eight healthy subjects recruited in our previous studies were used as a reference comparison. The in vivo kinematics of L3–L4 (the cephalic adjacent level to the degenerated discs) and L2–L3 (the level one above the adjacent level) lumbar discs of both groups were obtained using a combined magnetic resonance imaging and dual fluoroscopic imaging technique at functional postures. Deformation characteristics, in terms of areas of minimal deformation (defined as less than 5%), deformations at the center of the discs, and maximum tensile and shear deformations, were compared between the two groups at the two disc levels. Results In the patients with DDD, there were significantly smaller areas of minimal disc deformation at L3–L4 and L2–L3 than the healthy subjects (18% compared with 45% of the total disc area, on average). Both L2–L3 and L3–L4 discs underwent larger tensile and shear deformations in all postures than the healthy subjects. The maximum tensile deformations were higher by up to 23% (of the local disc height in standing) and the maximum shear deformations were higher by approximately 25% to 40% (of the local disc height in standing) compared with those of the healthy subjects. Conclusion Both the discs of the adjacent

  4. Modelling personal exposure to particulate air pollution: an assessment of time-integrated activity modelling, Monte Carlo simulation & artificial neural network approaches.

    PubMed

    McCreddin, A; Alam, M S; McNabola, A

    2015-01-01

    An experimental assessment of personal exposure to PM10 in 59 office workers was carried out in Dublin, Ireland. 255 samples of 24-h personal exposure were collected in real time over a 28 month period. A series of modelling techniques were subsequently assessed for their ability to predict 24-h personal exposure to PM10. Artificial neural network modelling, Monte Carlo simulation and time-activity based models were developed and compared. The results of the investigation showed that using the Monte Carlo technique to randomly select concentrations from statistical distributions of exposure concentrations in typical microenvironments encountered by office workers produced the most accurate results, based on 3 statistical measures of model performance. The Monte Carlo simulation technique was also shown to have the greatest potential utility over the other techniques, in terms of predicting personal exposure without the need for further monitoring data. Over the 28 month period only a very weak correlation was found between background air quality and personal exposure measurements, highlighting the need for accurate models of personal exposure in epidemiological studies. PMID:25260856

  5. Early clinical and radiographical results of keel-less and shallow keel cervical disc replacement

    PubMed Central

    Ling, Ji Min; Tiruchelvarayan, Rajendra

    2015-01-01

    Background: Cervical disc replacements has been shown to be as effective as fusions in the treatment of radiculopathy or myelopathy due to disc prolapse. Newer implants were designed to reduce the difficulty of end-plate preparation. Since 2010, the authors have started using Discocerv (Alphatec Spine, Carlsbad, USA) a keel-less implant and Activ-C (B. Braun, Sheffield, UK), a shallow keel implant. Aim: The aim of this study was to compare the duration of surgery between cervical disc replacement and anterior cervical discectomy and fusion, and also to evaluate the functional outcome, complications, and radiographic outcome of cervical disc replacement. Results: Fifty patients were included (20 disc replacement and 30 fusion). This was a single surgeon retrospective study, with all surgery performed by the senior author (RT). The mean operation duration for single-level disc replacement was 2.6 h, and for single-level fusion was 2.4 h (P = 0.4684). For 2-levels surgery, the result was 3.5 h for 2-level hybrid surgery (one level disc replacement and one level fusion) and 3.4 h for fusion (P = 0.4489). Disc replacement resulted in preservation of an average of 67% of the angle of motion at the sagittal plane (FFflexion-extension). The average range of motion after disc replacement was 6.1°. The median clinical follow-up duration was 2 years (average 1.8 years). There was no incidence of major complications or significant neurovascular injury in this series of patients. A significant improvement in short form-36 scores was seen as early as 3 months postoperative (from 58 preoperative to 92 at 3 months). The improvement was sustained up to the fourth year of follow-up. Conclusion: Cervical arthroplasty with keel-less and shallow keel implants are safe and relatively easy to perform. The surgical time for disc replacement is not significantly longer than standard fusion surgery. There is reasonably good preservation of motion. The short-term functional improvement is

  6. Using tea as an artificial urine in a Canadian performance testing program for fission/activation products.

    PubMed

    Daka, Joseph N; Moodie, Gerry; DiNardo, Anthony; Kramer, Gary H

    2014-12-01

    In recent years, the National Calibration Reference Centre for Bioassay and In Vivo Monitoring (NCRC) at the Radiation Protection Bureau (RPB), Health Canada, has been conducting investigations with black tea to develop a matrix that can be used to replace urine in each of the following performance testing programs (PTP): (1) tritium, (2) carbon-14, (3) the DUAL (i.e., 3H/14C), and (4) fission/activation products (F/AP). A 1% tea solution with thimerosal, which had worked successfully for tritium, carbon-14, and the DUAL, was selected and tested for the F/AP PTP because of its similarity to urine in color and UV-VIS spectra. However, application of this tea to samples of the F/AP program containing 133Ba, 137Cs, 57Co, and 60Co produced precipitates, which was an unexpected result. Further experiments showed that replacement of thimerosal with an alcohol at about 5% eliminated the precipitation problem. The alcohol can be ethanol, methanol, or isopropanol. In the experiments, the 1% tea, preserved with alcohol, remained clear and stable for at least 100 d. The duration of each PTP for the NCRC is limited to 90 d. Application of the CNSC S-106 regulatory standard to the tea produced acceptable accuracy and precision results. It was concluded that a suitable tea matrix for the F/AP program had been found. PMID:25353238

  7. CR TKA UHMWPE wear tested after artificial aging of the vitamin E treated gliding component by simulating daily patient activities.

    PubMed

    Schwiesau, Jens; Fritz, Bernhard; Kutzner, Ines; Bergmann, Georg; Grupp, Thomas M

    2014-01-01

    The wear behaviour of total knee arthroplasty (TKA) is dominated by two wear mechanisms: the abrasive wear and the delamination of the gliding components, where the second is strongly linked to aging processes and stress concentration in the material. The addition of vitamin E to the bulk material is a potential way to reduce the aging processes. This study evaluates the wear behaviour and delamination susceptibility of the gliding components of a vitamin E blended, ultra-high molecular weight polyethylene (UHMWPE) cruciate retaining (CR) total knee arthroplasty. Daily activities such as level walking, ascending and descending stairs, bending of the knee, and sitting and rising from a chair were simulated with a data set received from an instrumented knee prosthesis. After 5 million test cycles no structural failure of the gliding components was observed. The wear rate was with 5.62 ± 0.53 mg/million cycles falling within the limit of previous reports for established wear test methods. PMID:25506594

  8. CR TKA UHMWPE Wear Tested after Artificial Aging of the Vitamin E Treated Gliding Component by Simulating Daily Patient Activities

    PubMed Central

    Schwiesau, Jens; Fritz, Bernhard; Kutzner, Ines; Bergmann, Georg; Grupp, Thomas M.

    2014-01-01

    The wear behaviour of total knee arthroplasty (TKA) is dominated by two wear mechanisms: the abrasive wear and the delamination of the gliding components, where the second is strongly linked to aging processes and stress concentration in the material. The addition of vitamin E to the bulk material is a potential way to reduce the aging processes. This study evaluates the wear behaviour and delamination susceptibility of the gliding components of a vitamin E blended, ultra-high molecular weight polyethylene (UHMWPE) cruciate retaining (CR) total knee arthroplasty. Daily activities such as level walking, ascending and descending stairs, bending of the knee, and sitting and rising from a chair were simulated with a data set received from an instrumented knee prosthesis. After 5 million test cycles no structural failure of the gliding components was observed. The wear rate was with 5.62 ± 0.53 mg/million cycles falling within the limit of previous reports for established wear test methods. PMID:25506594

  9. Delivery systems for the treatment of degenerated intervertebral discs.

    PubMed

    Blanquer, S B G; Grijpma, D W; Poot, A A

    2015-04-01

    The intervertebral disc (IVD) is the most avascular and acellular tissue in the body and therefore prone to degeneration. During IVD degeneration, the balance between anabolic and catabolic processes in the disc is deregulated, amongst others leading to alteration of extracellular matrix production, abnormal enzyme activities and production of pro-inflammatory substances like cytokines. The established treatment strategy for IVD degeneration consists of physiotherapy, pain medication by drug therapy and if necessary surgery. This approach, however, has shown limited success. Alternative strategies to increase and prolong the effects of bioactive agents and to reverse the process of IVD degeneration include the use of delivery systems for drugs, proteins, cells and genes. In view of the specific anatomy and physiology of the IVD and depending on the strategy of the therapy, different delivery systems have been developed which are reviewed in this article. PMID:25451138

  10. Progranulin Knockout Accelerates Intervertebral Disc Degeneration in Aging Mice

    PubMed Central

    Zhao, Yun-peng; Tian, Qing-yun; Liu, Ben; Cuellar, Jason; Richbourgh, Brendon; Jia, Tang-hong; Liu, Chuan-ju

    2015-01-01

    Intervertebral disc (IVD) degeneration is a common degenerative disease, yet much is unknown about the mechanisms during its pathogenesis. Herein we investigated whether progranulin (PGRN), a chondroprotective growth factor, is associated with IVD degeneration. PGRN was detectable in both human and murine IVD. The levels of PGRN were upregulated in murine IVD tissue during aging process. Loss of PGRN resulted in an early onset of degenerative changes in the IVD tissue and altered expressions of the degeneration-associated molecules in the mouse IVD tissue. Moreover, PGRN knockout mice exhibited accelerated IVD matrix degeneration, abnormal bone formation and exaggerated bone resorption in vertebra with aging. The acceleration of IVD degeneration observed in PGRN null mice was probably due to the enhanced activation of NF-κB signaling and β-catenin signaling. Taken together, PGRN may play a critical role in homeostasis of IVD, and may serve as a potential molecular target for prevention and treatment of disc degenerative diseases. PMID:25777988

  11. Magnetorotationally driven wind cycles in local disc models

    NASA Astrophysics Data System (ADS)

    Riols, A.; Ogilvie, G. I.; Latter, H.; Ross, J. P.

    2016-09-01

    Jets, from the protostellar to the AGN context, have been extensively studied but their connection to the turbulent dynamics of the underlying accretion disc is poorly understood. Following a similar approach to Lesur et al. (2013), we examine the role of the magnetorotational instability (MRI) in the production and acceleration of outflows from discs. Via a suite of one-dimensional shearing-box simulations of stratified discs we show that magneto-centrifugal winds exhibit cyclic activity with a period of 10 - 20 Ω-1, a few times the orbital period. The cycle seems to be more vigorous for strong vertical field; it is robust to the variation of relevant parameters and independent of numerical details. The convergence of these solutions (in particular the mass loss rate) with vertical box size is also studied. By considering a sequence of magnetohydrostatic equilibria and their stability, the periodic activity may be understood as the succession of the following phases: (a) a dominant MRI channel mode, (b) strong magnetic field generation, (c) consequent wind launching, and ultimately (d) vertical expulsion of the excess magnetic field by the expanding and accelerating gas associated with the wind. We discuss potential connections between this behaviour and observed time-variability in disk-jet systems.

  12. The Latest Lessons Learned from Retrieval Analyses of Ultra-High Molecular Weight Polyethylene, Metal-on-Metal, and Alternative Bearing Total Disc Replacements

    PubMed Central

    Kurtz, Steven M.; Toth, Jeffrey M.; Siskey, Ryan; Ciccarelli, Lauren; MacDonald, Dan; Isaza, Jorge; Lanman, Todd; Punt, Ilona; Steinbeck, Marla; Goffin, Jan; van Ooij, André

    2012-01-01

    Knowledge regarding the in vivo performance and periposthetic tissue response of cervical and lumbar total disc replacements (TDRs) continues to expand. This review addresses the following four main questions: 1) What are the latest lessons learned from polyethylene in large joints and how are they relevant to current TDRs? 2) What are the latest lessons learned regarding adverse local tissue reactions from metal-on-metal, CoCr bearings in large joints and how are they relevant to current TDRs? 3) What advancements have been made in understanding the in vivo performance of alternative biomaterials, such as stainless steel and polycarbonate urethane, for TDRs in the past five years? 4) How has retrieval analysis of all these various artificial disc bearing technologies advanced the state of the art in preclinical testing of TDRs? The study of explanted artificial discs and their associated tissues can help inform bearing selection as well as the design of future generations of disc arthroplasty. Analyzing retrieved artificial discs is also essential for validating preclinical test methods. PMID:22904606

  13. Artificial Astrocytes Improve Neural Network Performance

    PubMed Central

    Porto-Pazos, Ana B.; Veiguela, Noha; Mesejo, Pablo; Navarrete, Marta; Alvarellos, Alberto; Ibáñez, Oscar; Pazos, Alejandro; Araque, Alfonso

    2011-01-01

    Compelling evidence indicates the existence of bidirectional communication between astrocytes and neurons. Astrocytes, a type of glial cells classically considered to be passive supportive cells, have been recently demonstrated to be actively involved in the processing and regulation of synaptic information, suggesting that brain function arises from the activity of neuron-glia networks. However, the actual impact of astrocytes in neural network function is largely unknown and its application in artificial intelligence remains untested. We have investigated the consequences of including artificial astrocytes, which present the biologically defined properties involved in astrocyte-neuron communication, on artificial neural network performance. Using connectionist systems and evolutionary algorithms, we have compared the performance of artificial neural networks (NN) and artificial neuron-glia networks (NGN) to solve classification problems. We show that the degree of success of NGN is superior to NN. Analysis of performances of NN with different number of neurons or different architectures indicate that the effects of NGN cannot be accounted for an increased number of network elements, but rather they are specifically due to astrocytes. Furthermore, the relative efficacy of NGN vs. NN increases as the complexity of the network increases. These results indicate that artificial astrocytes improve neural network performance, and established the concept of Artificial Neuron-Glia Networks, which represents a novel concept in Artificial Intelligence with implications in computational science as well as in the understanding of brain function. PMID:21526157

  14. Artificial astrocytes improve neural network performance.

    PubMed

    Porto-Pazos, Ana B; Veiguela, Noha; Mesejo, Pablo; Navarrete, Marta; Alvarellos, Alberto; Ibáñez, Oscar; Pazos, Alejandro; Araque, Alfonso

    2011-01-01

    Compelling evidence indicates the existence of bidirectional communication between astrocytes and neurons. Astrocytes, a type of glial cells classically considered to be passive supportive cells, have been recently demonstrated to be actively involved in the processing and regulation of synaptic information, suggesting that brain function arises from the activity of neuron-glia networks. However, the actual impact of astrocytes in neural network function is largely unknown and its application in artificial intelligence remains untested. We have investigated the consequences of including artificial astrocytes, which present the biologically defined properties involved in astrocyte-neuron communication, on artificial neural network performance. Using connectionist systems and evolutionary algorithms, we have compared the performance of artificial neural networks (NN) and artificial neuron-glia networks (NGN) to solve classification problems. We show that the degree of success of NGN is superior to NN. Analysis of performances of NN with different number of neurons or different architectures indicate that the effects of NGN cannot be accounted for an increased number of network elements, but rather they are specifically due to astrocytes. Furthermore, the relative efficacy of NGN vs. NN increases as the complexity of the network increases. These results indicate that artificial astrocytes improve neural network performance, and established the concept of Artificial Neuron-Glia Networks, which represents a novel concept in Artificial Intelligence with implications in computational science as well as in the understanding of brain function. PMID:21526157

  15. In silico evaluation of a new composite disc substitute with a L3-L5 lumbar spine finite element model.

    PubMed

    Noailly, Jérôme; Ambrosio, Luigi; Elizabeth Tanner, K; Planell, Josep A; Lacroix, Damien

    2012-06-01

    When the intervertebral disc is removed to relieve chronic pain, subsequent segment stabilization should restore the functional mechanics of the native disc. Because of partially constrained motions and the lack of intrinsic rotational stiffness ball-on-socket implants present many disadvantages. Composite disc substitutes mimicking healthy disc structures should be able to assume the role expected for a disc substitute with fewer restrictions than ball-on-socket implants. A biomimetic composite disc prototype including artificial nucleus fibre-reinforced annulus and endplates was modelled as an L4-L5 disc substitute within a L3-L5 lumbar spine finite element model. Different device updates, i.e. changes of material properties fibre distributions and volume fractions and nucleus placements were proposed. Load- and displacement-controlled rotations were simulated with and without body weight applied. The original prototype reduced greatly the flexibility of the treated segment with significant adjacent level effects under displacement-controlled or hybrid rotations. Device updates allowed restoring large part of the global axial and sagittal rotational flexibility predicted with the intact model. Material properties played a major role, but some other updates were identified to potentially tune the device behaviour against specific motions. All device versions altered the coupled intersegmental shear deformations affecting facet joint contact through contact area displacements. Loads in the bony endplates adjacent to the implants increased as the implant stiffness decreased but did not appear to be a strong limitation for the implant biomechanical and mechanobiological functionality. In conclusion, numerical results given by biomimetic composite disc substitutes were encouraging with greater potential than that offered by ball-on-socket implants. PMID:21380572

  16. The first velocity space image of a planetary debris disc orbiting a white dwarf

    NASA Astrophysics Data System (ADS)

    Manser, Christopher James

    2015-12-01

    Since the first ESS meeting, dusty debris discs at white dwarfs have been firmly established as signposts of evolved planetary systems. We have identified a small number of systems where the circumstellar dust is accompanied by gas. The emission lines from these gaseous components are tracers of dynamic activity in these remnant planetary environments, and provide unparalleled insight into the formation and evolution of the debris discs, and into the properties of the parent planetesimals.Here we present the twelve years of spectroscopy of the prototypical gas disc at SDSS J1228+1040, revealing a spectacular long-term evolution in the morphology of the emission line profiles. Using Doppler tomography, we constructed an image of the gaseous disc in velocity space, and show that the observations are consistent with the precession of a fixed intensity pattern on a period of 27 ± 3 years. We speculate that the underlying cause of this dynamical activity is either a young, not fully circularised disc, or a perturbation of a previously stable and quiescent disc.

  17. [Biomechanical analysis of different ProDisc-C arthroplasty design parameters after implanted: a numerical sensitivity study based on finite element method].

    PubMed

    Tang, Qiaohong; Mo, Zhongjun; Yao, Jie; Li, Qi; Du, Chenfei; Wang, Lizhen; Fan, Yubo

    2014-12-01

    This study was aimed to estimate the effect of different ProDisc-C arthroplasty designs after it was implanted to C5-C6 cervicalspine. Finite element (FE) model of intact C5-C6 segments including the vertebrae and disc was developed and validated. Ball-and-socket artificial disc prosthesis model (ProDisc-C, Synthes) was implanted into the validated FE model and the curvature of the ProDisc-C prosthesis was varied. All models were loaded with compressed force 74 N and the pure moment of 1.8 Nm along flexion-extension and bilateral bending and axial torsion separately. The results indicated that the variation in the curvature of ball and socket configuration would influence the range of motion in flexion/extension, while there were not apparently differences under other conditions of loads. The method increasing the curvature will solve the stress concentration of the polyethylene, but it will also bring adverse outcomes, such as facet joint force increasing and ligament tension increasing. Therefore, the design of artificial discs should be considered comprehensively to reserve the range of motion as well as to avoid the adverse problems, so as not to affect the long-term clinical results. PMID:25868242

  18. Annulo-nucleoplasty using Disc-FX in the management of lumbar disc pathology: Early results

    PubMed Central

    Kumar, Aravind; Siddharth M, Shah; Sambhav P, Shah; Tan, Justin

    2014-01-01

    Background Back pain due to Lumbar Disc Disease is a major clinical problem. The treatment options range from physiotherapy to fusion surgery. A number of minimally invasive procedures have also been developed in the recent past for its management. Disc-FX is a new minimally invasive technique that combines percutaneous discectomy, nuclear ablation and annular modification. Literature on its role in the management of lumbar disc pathology is scarce. Methods We included 24 consecutive patients who underwent the Disc-FX for back pain due to lumbar disc pathology non-responsive to non-operative treatment for a period of at least 6 months. Based on Magnetic Resonance Imaging (MRI) these patients fell into 2 groups – those with degenerative disc disease (DDD) (n = 12) and those with a contained lumbar disc herniation (CLDH)(n = 12). They were evaluated using the Visual analogue scale (VAS), Oswestry Disability Index (ODI) and Short Form-36 (SF-36) scores preoperatively and postoperatively. Results The mean age was 37.9 years (21-53 years). There were 17 males and 7 females. One patient in each subgroup was excluded from the final evaluation. Significant improvement was seen in all outcome measures. The overall rate of reintervention for persistent symptoms was 18.18% (4/22); in the CLDH subgroup, it was 36.36% (4/11). Conclusions and level of evidence Early results after the Disc-FX procedure suggest that it s a reasonable treatment option for patients with back pain due to lumbar disc disease, especially for those with DDD who fail conservative treatment. It could be an alternative to procedures like fusion or disc replacement. This study presents Level IV evidence. Clinical relevance We feel that our study establishes Disc-FX as a modality of treating symptomatic lumbar disc disease due to DDD. However, longer term prospective studies are needed to prove this and to evaluate its role in the treatment of patients with CLDH. PMID:25694914

  19. Artificial Intelligence for the Evaluation of Operational Parameters Influencing Nitrification and Nitrifiers in an Activated Sludge Process.

    PubMed

    Awolusi, Oluyemi Olatunji; Nasr, Mahmoud; Kumari, Sheena; Bux, Faizal

    2016-07-01

    Nitrification at a full-scale activated sludge plant treating municipal wastewater was monitored over a period of 237 days. A combination of fluorescent in situ hybridization (FISH) and quantitative real-time polymerase chain reaction (qPCR) were used for identifying and quantifying the dominant nitrifiers in the plant. Adaptive neuro-fuzzy inference system (ANFIS), Pearson's correlation coefficient, and quadratic models were employed in evaluating the plant operational conditions that influence the nitrification performance. The ammonia-oxidizing bacteria (AOB) abundance was within the range of 1.55 × 10(8)-1.65 × 10(10) copies L(-1), while Nitrobacter spp. and Nitrospira spp. were 9.32 × 10(9)-1.40 × 10(11) copies L(-1) and 2.39 × 10(9)-3.76 × 10(10) copies L(-1), respectively. Specific nitrification rate (qN) was significantly affected by temperature (r 0.726, p 0.002), hydraulic retention time (HRT) (r -0.651, p 0.009), and ammonia loading rate (ALR) (r 0.571, p 0.026). Additionally, AOB was considerably influenced by HRT (r -0.741, p 0.002) and temperature (r 0.517, p 0.048), while HRT negatively impacted Nitrospira spp. (r -0.627, p 0.012). A quadratic combination of HRT and food-to-microorganism (F/M) ratio also impacted qN (r (2) 0.50), AOB (r (2) 0.61), and Nitrospira spp. (r (2) 0.72), while Nitrobacter spp. was considerably influenced by a polynomial function of F/M ratio and temperature (r (2) 0.49). The study demonstrated that ANFIS could be used as a tool to describe the factors influencing nitrification process at full-scale wastewater treatment plants. PMID:26906468

  20. Archival-grade optical disc design and international standards

    NASA Astrophysics Data System (ADS)

    Fujii, Toru; Kojyo, Shinichi; Endo, Akihisa; Kodaira, Takuo; Mori, Fumi; Shimizu, Atsuo

    2015-09-01

    Optical discs currently on the market exhibit large variations in life span among discs, making them unsuitable for certain business applications. To assess and potentially mitigate this problem, we performed accelerated degradation testing under standard ISO conditions, determined the probable disc failure mechanisms, and identified the essential criteria necessary for a stable disc composition. With these criteria as necessary conditions, we analyzed the physical and chemical changes that occur in the disc components, on the basis of which we determined technological measures to reduce these degradation processes. By applying these measures to disc fabrication, we were able to develop highly stable optical discs.

  1. Apple Fool! An Introduction to Artificial Flavors.

    ERIC Educational Resources Information Center

    Journal of Chemical Education, 2003

    2003-01-01

    Presents a science activity on consumer chemistry in which students explore artificial flavors that are commonly used in foods, such as isoamyl acetate and methyl salicylate. Includes instructor information and a student worksheet. (YDS)

  2. Stellar motion induced by gravitational instabilities in protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Michael, Scott; Durisen, R. H.

    2010-07-01

    We test the effect of assumptions about stellar motion on the behaviour of gravitational instabilities (GIs) in protoplanetary discs around solar-type stars by performing two simulations that are identical in all respects except the treatment of the star. In one simulation, the star is assumed to remain fixed at the centre of the inertial reference frame. In the other, stellar motion is handled properly by including an indirect potential in the hydrodynamic equations to model the star's reference frame as one which is accelerated by star/disc interactions. The discs in both simulations orbit a solar mass star, initially extend from 2.3 to 40 au with a ϖ-1/2 surface density profile, and have a total mass of 0.14 Msolar. The γ = 5/3 ideal gas is assumed to cool everywhere with a constant cooling time of two outer rotation periods. The overall behaviour of the disc evolution is similar, except for weakening in various measures of GI activity by about at most tens of per cent for the indirect potential case. Overall conclusions about disc evolution in earlier papers by our group, where the star was always assumed to be fixed in an inertial frame, remain valid. There is no evidence for independent one-armed instabilities, like the Stimulation by the Long-range Interaction of Newtonian Gravity (SLING), in either simulation. On the other hand, the stellar motion about the system centre of mass (COM) in the simulation with the indirect potential is substantial, up to 0.25 au during the burst phase, as GIs initiate, and averaging about 0.9 au during the asymptotic phase, when the GIs reach an overall balance of heating and cooling. These motions appear to be a stellar response to non-linear interactions between discrete global spiral modes in both the burst and asymptotic phases of the evolution, and the star's orbital motion about the COM reflects the orbit periods of disc material near the corotation radii of the dominant spiral waves. This motion is, in principle

  3. Treatment of lumbar disc herniation by percutaneous laser disc decompression (PLDD) and modified PLDD

    NASA Astrophysics Data System (ADS)

    Chi, Xiao fei; Li, Hong zhi; Wu, Ru zhou; Sui, Yun xian

    2005-07-01

    Objective: To study the micro-invasive operative method and to compare the effect of treatment of PLDD and modified PLDD for Lumbar Disc Herniation. Method: Vaporized part of the nucleus pulposus in single or multiple point after acupuncture into lumbar disc, to reach the purpose of the decompression of the lumbar disc. Result: Among the 19 cases of the regular PLDD group, the excellent and good rate was 63.2%, and among the 40 cases of the modified PLDD group, the excellent and good rate was 82.5%. Conclusion: The modified PLDD has good effect on the treatment for lumbar disc herniation.

  4. [Spontaneous resolution of a lumbar disc herniation].

    PubMed

    Gelabert-González, M; Serramito-García, R; Aran-Echabe, E; García-Allut, A

    2007-04-01

    Lumbar disc herniation is a common cause of lower leg radiculopathy and the most effective methods of treatment remain in question. Both surgical and nonsurgical treatments may provide a successful outcome in appropriately selected patients. The spontaneous resolution of herniated lumbar discs is a well-established phenomenon. The authors present a case of spontaneous regression of a herniated lumbar nucleus pulpous in a patient with radiculopathy. PMID:17497061

  5. Disc valve for sampling erosive process streams

    DOEpatents

    Mrochek, John E.; Dinsmore, Stanley R.; Chandler, Edward W.

    1986-01-01

    A four-port disc valve for sampling erosive, high temperature process streams. A rotatable disc defining opposed first and second sampling cavities rotates between fired faceplates defining flow passageways positioned to be alternatively in axial alignment with the first and second cavities. Silicon carbide inserts and liners composed of .alpha. silicon carbide are provided in the faceplates and in the sampling cavities to limit erosion while providing lubricity for a smooth and precise operation when used under harsh process conditions.

  6. Mach disc formation in cylindrical recovery systems

    SciTech Connect

    Morris, C.E.; McQueen, R.G.; Marsh, S.P.

    1983-01-01

    Cylindrical recovery systems have been used to shock-load polymers to pressures exceeding 50 GPa. In order to determine the pressures generated in these recovery systems the formation of the Mach disc on axis and its approach to steady state was monitored. The relation of the Mach disc diameter to the lateral dimension of the high explosive used to compress the polymer samples was also investigated.

  7. Myoblast cytonemes mediate Wg signaling from the wing imaginal disc and Delta-Notch signaling to the air sac primordium

    PubMed Central

    Huang, Hai; Kornberg, Thomas B

    2015-01-01

    The flight muscles, dorsal air sacs, wing blades, and thoracic cuticle of the Drosophila adult function in concert, and their progenitor cells develop together in the wing imaginal disc. The wing disc orchestrates dorsal air sac development by producing decapentaplegic and fibroblast growth factor that travel via specific cytonemes in order to signal to the air sac primordium (ASP). Here, we report that cytonemes also link flight muscle progenitors (myoblasts) to disc cells and to the ASP, enabling myoblasts to relay signaling between the disc and the ASP. Frizzled (Fz)-containing myoblast cytonemes take up Wingless (Wg) from the disc, and Delta (Dl)-containing myoblast cytonemes contribute to Notch activation in the ASP. Wg signaling negatively regulates Dl expression in the myoblasts. These results reveal an essential role for cytonemes in Wg and Notch signaling and for a signal relay system in the myoblasts. DOI: http://dx.doi.org/10.7554/eLife.06114.001 PMID:25951303

  8. Sagittal plane rotation center of lower lumbar spine during a dynamic weight-lifting activity.

    PubMed

    Liu, Zhan; Tsai, Tsung-Yuan; Wang, Shaobai; Wu, Minfei; Zhong, Weiye; Li, Jing-Sheng; Cha, Thomas; Wood, Kirk; Li, Guoan

    2016-02-01

    This study investigated the center of rotation (COR) of the intervertebral segments of the lower lumbar spine (L4-L5 and L5-S1 segments) in sagittal plane during a weight-lifting (3.6 kg in each hand) extension activity performed with the pelvis constrained. Seven healthy subjects were studied using a dual fluoroscopic imaging technique. Using the non-weightbearing, supine position during MRI scan as a reference, the average intervertebral flexion angles of the L4-L5 and L5-S1 were 6.6° and 5.3° at flexion position of the body, respectively, and were -1.8° and -3.5° at extension position of the body, respectively. The CORs of the lower lumbar spine were found segment-dependent and changed with the body postures. The CORs of the L4-L5 segment were at the location about 75% posterior from the anterior edge of the disc at flexion positions of the body, and moved to about 92% of the posterior portion of the disc at extension positions of the body. The CORs of the L5-S1 segment were at 95% posterior portion of the disc at flexion positions of the body, and moved outside of the posterior edge of the disc by about 12% of the disc length at extension positions of the body. These results could help understand the physiological motion characters of the lower lumbar spine. The data could also provide important insights for future improvement of artificial disc designs and surgical implantation of the discs that are aimed to reproduce normal spinal functions. PMID:26805460

  9. Discovery of the Fomalhaut C debris disc

    NASA Astrophysics Data System (ADS)

    Kennedy, G. M.; Wyatt, M. C.; Kalas, P.; Duchêne, G.; Sibthorpe, B.; Lestrade, J.-F.; Matthews, B. C.; Greaves, J.

    2014-02-01

    Fomalhaut is one of the most interesting and well-studied nearby stars, hosting at least one planet, a spectacular debris ring and two distant low-mass stellar companions (TW PsA and LP 876-10, a.k.a. Fomalhaut B and C). We observed both companions with Herschel, and while no disc was detected around the secondary, TW PsA, we have discovered the second debris disc in the Fomalhaut system, around LP 876-10. This detection is only the second case of two debris discs seen in a multiple system, both of which are relatively wide (≳3000 au for HD 223352/40 and 158 kau [0.77 pc] for Fomalhaut/LP 876-10). The disc is cool (24 K) and relatively bright, with a fractional luminosity Ldisc/L⋆ = 1.2 × 10-4, and represents the rare observation of a debris disc around an M dwarf. Further work should attempt to find if the presence of two discs in the Fomalhaut system is coincidental, perhaps simply due to the relatively young system age of 440 Myr, or if the stellar components have dynamically interacted and the system is even more complex than it currently appears.

  10. Modeling Jupiter's current disc: Pioneer 10 outbound

    SciTech Connect

    Jones, D.E.; Melville, J.G. II; Blake, M.L.

    1980-07-01

    The magnetic field of the Jovian current disc has been modeled by using Euler functions and the Biot-Savart law applied to a series of concentric, but not necessarily coplanar, current rings. We find that a best fit to the Pioneer 10 outbound perturbation magnetic field data (B/sub total/-B/sub dipole/) is obtained if the current disc is twisted (outer edges increasingly lag behind inner edges with radial distance) and also bent so as to tend toward parallelism with the Jovigraphic equator. The inner and outer radii of the disc appear to be about 7 R/sub J/ and 150 R/sub J/, respectively, although some indication of a changing magnetopause location is apparent in the data. Because of the observed current disc penetrations, the bent disc also requires a deformation in the form of a bump or wrinkle whose axis tends also to exhibit spiraling. The radial dependence of the azimuthal current in the disc is not described by a simple power law, the outer region showing a smaller power law dependence. Modeling of the azimuthal field shows it to be due to a thin radial current sheet, but there is some evidence that this may, in fact, be due in large part to penetration of a tail current sheet as suggested by the Voyager observations.

  11. Optic disc anomalies and frontonasal dysplasia

    PubMed Central

    Hodgkins, P; Lees, M; Lawson, J; Reardon, W; Leitch, J; Thorogood, P; Winter, R; Taylor, D

    1998-01-01

    AIMS—To document the optic disc abnormalities in patients with frontonasal dysplasia in association with basal encephalocele.
METHODS—Names and hospital numbers of patients with midline clefts were obtained from the ophthalmology and genetics database. Six patients were identified who had the following common findings: midline facial cleft with midline cleft lip and palate; hypertelorism; absent corpus callosum; basal (sphenoethmoidal) encephalocele; and pituitary deficiency (five out of six cases). Ophthalmic examination was performed with fundal photography where possible.
RESULTS—Two patients had unilateral and one a bilateral peripapillary staphyloma. Two patients had bilateral optic disc hypoplasia and one appeared to have a peripapillary staphyloma in one eye and a morning glory disc in the other.
CONCLUSION—Optic disc abnormalities were found in all patients with this constellation of clinical findings. This association appears to represent a distinct subgroup within the spectrum of frontonasal dysplasia. The presence of midline facial anomalies and any dysplastic disc should alert the physician as to the presence of an encephalocele.

 Keywords: frontonasal dysplasia; optic disc; encephalocele PMID:9602627

  12. The diversity of thick galactic discs

    NASA Astrophysics Data System (ADS)

    Kasparova, Anastasia V.; Katkov, Ivan Yu.; Chilingarian, Igor V.; Silchenko, Olga K.; Moiseev, Alexey V.; Borisov, Svyatoslav B.

    2016-07-01

    Although thick stellar discs are detected in nearly all edge-on disc galaxies, their formation scenarios still remain a matter of debate. Due to observational difficulties, there is a lack of information about their stellar populations. Using the Russian 6-m telescope BTA we collected deep spectra of thick discs in three edge-on S0-a disc galaxies located in different environments: NGC 4111 in a dense group, NGC 4710 in the Virgo cluster, and NGC 5422 in a sparse group. We see intermediate age (4-5 Gyr) metal rich ([Fe/H] ˜- 0.2…0.0 dex) stellar populations in NGC 4111 and NGC 4710. On the other hand, NGC 5422 does not harbour young stars, its disc is thick and old (10 Gyr), without evidence for a second component, and its α-element abundance suggests a 1.5-2 Gyr long formation epoch implying its formation at high redshift. Our results suggest the diversity of thick disc formation scenarios.

  13. Circumplanetary disc or circumplanetary envelope?

    NASA Astrophysics Data System (ADS)

    Szulágyi, J.; Masset, F.; Lega, E.; Crida, A.; Morbidelli, A.; Guillot, T.

    2016-08-01

    We present three-dimensional simulations with nested meshes of the dynamics of the gas around a Jupiter mass planet with the JUPITER and FARGOCA codes. We implemented a radiative transfer module into the JUPITER code to account for realistic heating and cooling of the gas. We focus on the circumplanetary gas flow, determining its characteristics at very high resolution (80 per cent of Jupiter's diameter). In our nominal simulation where the temperature evolves freely by the radiative module and reaches 13000 K at the planet, a circumplanetary envelope was formed filling the entire Roche lobe. Because of our equation of state is simplified and probably overestimates the temperature, we also performed simulations with limited maximal temperatures in the planet region (1000, 1500, and 2000 K). In these fixed temperature cases circumplanetary discs (CPDs) were formed. This suggests that the capability to form a CPD is not simply linked to the mass of the planet and its ability to open a gap. Instead, the gas temperature at the planet's location, which depends on its accretion history, plays also fundamental role. The CPDs in the simulations are hot and cooling very slowly, they have very steep temperature and density profiles, and are strongly sub-Keplerian. Moreover, the CPDs are fed by a strong vertical influx, which shocks on the CPD surfaces creating a hot and luminous shock-front. In contrast, the pressure supported circumplanetary envelope is characterized by internal convection and almost stalled rotation.

  14. Artificial neural network and particle swarm optimization for removal of methyl orange by gold nanoparticles loaded on activated carbon and Tamarisk

    NASA Astrophysics Data System (ADS)

    Ghaedi, M.; Ghaedi, A. M.; Ansari, A.; Mohammadi, F.; Vafaei, A.

    2014-11-01

    The influence of variables, namely initial dye concentration, adsorbent dosage (g), stirrer speed (rpm) and contact time (min) on the removal of methyl orange (MO) by gold nanoparticles loaded on activated carbon (Au-NP-AC) and Tamarisk were investigated using multiple linear regression (MLR) and artificial neural network (ANN) and the variables were optimized by partial swarm optimization (PSO). Comparison of the results achieved using proposed models, showed the ANN model was better than the MLR model for prediction of methyl orange removal using Au-NP-AC and Tamarisk. Using the optimal ANN model the coefficient of determination (R2) for the test data set were 0.958 and 0.989; mean squared error (MSE) values were 0.00082 and 0.0006 for Au-NP-AC and Tamarisk adsorbent, respectively. In this study a novel and green approach were reported for the synthesis of gold nanoparticle and activated carbon by Tamarisk. This material was characterized using different techniques such as SEM, TEM, XRD and BET. The usability of Au-NP-AC and activated carbon (AC) Tamarisk for the methyl orange from aqueous solutions was investigated. The effect of variables such as pH, initial dye concentration, adsorbent dosage (g) and contact time (min) on methyl orange removal were studied. Fitting the experimental equilibrium data to various isotherm models such as Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show the suitability and applicability of the Langmuir model. Kinetic models such as pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models indicate that the second-order equation and intraparticle diffusion models control the kinetic of the adsorption process. The small amount of proposed Au-NP-AC and activated carbon (0.015 g and 0.75 g) is applicable for successful removal of methyl orange (>98%) in short time (20 min for Au-NP-AC and 45 min for Tamarisk-AC) with high adsorption capacity 161 mg g-1 for Au-NP-AC and 3.84 mg g-1 for Tamarisk-AC.

  15. Artificial neural network and particle swarm optimization for removal of methyl orange by gold nanoparticles loaded on activated carbon and Tamarisk.

    PubMed

    Ghaedi, M; Ghaedi, A M; Ansari, A; Mohammadi, F; Vafaei, A

    2014-11-11

    The influence of variables, namely initial dye concentration, adsorbent dosage (g), stirrer speed (rpm) and contact time (min) on the removal of methyl orange (MO) by gold nanoparticles loaded on activated carbon (Au-NP-AC) and Tamarisk were investigated using multiple linear regression (MLR) and artificial neural network (ANN) and the variables were optimized by partial swarm optimization (PSO). Comparison of the results achieved using proposed models, showed the ANN model was better than the MLR model for prediction of methyl orange removal using Au-NP-AC and Tamarisk. Using the optimal ANN model the coefficient of determination (R2) for the test data set were 0.958 and 0.989; mean squared error (MSE) values were 0.00082 and 0.0006 for Au-NP-AC and Tamarisk adsorbent, respectively. In this study a novel and green approach were reported for the synthesis of gold nanoparticle and activated carbon by Tamarisk. This material was characterized using different techniques such as SEM, TEM, XRD and BET. The usability of Au-NP-AC and activated carbon (AC) Tamarisk for the methyl orange from aqueous solutions was investigated. The effect of variables such as pH, initial dye concentration, adsorbent dosage (g) and contact time (min) on methyl orange removal were studied. Fitting the experimental equilibrium data to various isotherm models such as Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show the suitability and applicability of the Langmuir model. Kinetic models such as pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models indicate that the second-order equation and intraparticle diffusion models control the kinetic of the adsorption process. The small amount of proposed Au-NP-AC and activated carbon (0.015 g and 0.75 g) is applicable for successful removal of methyl orange (>98%) in short time (20 min for Au-NP-AC and 45 min for Tamarisk-AC) with high adsorption capacity 161 mg g(-1) for Au-NP-AC and 3.84 mg g(-1) for

  16. Overview: DVD-video disc set of seafloor transects during USGS research cruises in the Pacific Ocean

    USGS Publications Warehouse

    Chezar, Henry; Newman, Ivy

    2006-01-01

    Many USGS research programs involve the gathering of underwater seafloor video footage. This footage was captured on a variety of media, including Beta III and VHS tapes. Much of this media is now deteriorating, prompting the migration of this video footage onto DVD-Video discs. Advantages of using DVD-Video discs are: less storage space, ease of transport, wider distribution, and non-degradational viewing of the media. The videos in this particular collection (328 of them) were made on the ocean floor under President Reagan's Exclusive Economic Zone proclamation of 1983. There are now five copies of these 328 discs in existence: at the USGS libraries in Menlo Park, Calif., Denver, Colo., and Reston, Va.; at the USGS Publications Warehouse (masters from which to make copies for customers); and Hank Chezar's USGS Western Coastal and Marine Geology team archives. The purpose of Open-File Report 2004-1101 is to provide users with a listing of the available DVD-Video discs (with their Open-File Report numbers) along with a brief description of their associated USGS research activities. Each disc was created by first encoding the source video and audio into MPEG-2 streams using the MediaPress Pro hardware encoder. A menu for the disc was then made using Adobe Photoshop 6.0. The disc was then authored using DVD Studio Pro and subsequently written onto a DVD-R recordable disc.

  17. Action of fibroblast growth factor-2 on the intervertebral disc

    PubMed Central

    Li, Xin; An, Howard S; Ellman, Michael; Phillips, Frank; Thonar, Eugene J; Park, Daniel K; Udayakumar, Ranjith K; Im, Hee-Jeong

    2008-01-01

    Introduction Fibroblast growth factor 2 (FGF2) is a growth factor that is immediately released after cartilage injury and plays a pivotal role in cartilage homeostasis. In human adult articular cartilage, FGF2 mediates anti-anabolic and potentially catabolic effects via the suppression of proteoglycan (PG) production along with the upregulation of matrix-degrading enzyme activity. The aim of the present study was to determine the biological effects of FGF2 in spine disc cells and to elucidate the complex biochemical pathways utilized by FGF2 in bovine intervertebral disc (IVD) cells in an attempt to further understand the pathophysiologic processes involved in disc degeneration. Methods We studied the effect of FGF2 on IVD tissue homeostasis by assessing MMP-13 expression (potent matrix-degrading enzyme), PG accumulation, and PG synthesis in the bovine spine IVD, as well as evaluating whether FGF2 counteracts known anabolic factors such as BMP7. To understand the molecular mechanisms by which FGF2 antagonizes BMP7 activity, we also investigated the signaling pathways utilized by FGF2 in bovine disc tissue. Results The primary receptor expressed in bovine nucleus pulposus cartilage is FGFR1, and this receptor is upregulated in degenerative human IVD tissue compared with normal IVD tissue. Stimulation of bovine nucleus pulposus cells cultured in monolayer with FGF2 augmented the production of MMP-13 at the transcriptional and translational level in a dose-dependent manner. Stimulation of bovine nucleus pulposus cells cultured in alginate beads for 21 days with FGF2 resulted in a dose-dependent decrease in PG accumulation, due at least in part to the inhibition of PG synthesis. Further studies demonstrate that FGF2 (10 ng/ml) antagonizes BMP7-mediated acceleration of PG production in bovine nucleus pulposus cells via the upregulation of noggin, an inhibitor of the transforming growth factor beta/bone morphogenetic protein signaling pathway. Chemical inhibitor studies

  18. Compressive vs Solenoidal Turbulence and Violent Disc Instability

    NASA Astrophysics Data System (ADS)

    Mandelker, Nir; Dekel, Avishai; Inoue, Shigeki; Ceverino, Daniel; Primack, Joel

    2015-08-01

    High redshift star-forming galaxies (SFGs) exhibit star-formation rates (SFR) 20-100 times higher than local SFGs. This increased SFR is due to much higher gas fractions and surface densities prevalent in high redshift SFG. Such high gas fractions cause the disc to become violently unstable and undergo a phase of violent disc instability (VDI). During the VDI phase, there is rapid inflow of gas towards the galactic centre with inflow times comparable to the disc orbital time, which can lead to a compact "blue nugget". In addition, giant ~kpc scale star-forming clumps are formed, the most massive of which survive dtellar feedback and migrate towards the centre, where they coalesce in the growing bulge. While the existence of giant clumps is commonly associated with Toomre instability, high resolution cosmological simulations of galaxy formation show that active clump formation occurs even in regions where the Toomre Q parameter is well above the threshold for stability. The simulations suggest instead a non-linear instability, where frequent minor mergers and intense inflow by cold streams increase the compressive mode of turbulence relative to the solenoidal mode. We find this can induce clump formation even in regions that should be stable according to linear Toomre theory. Thus we show that mergers, smooth accretion from the cosmic web and VDI all go hand in hand in driving galaxy evolution at high redshift.

  19. Disc outflows and high-luminosity true type 2 AGN

    NASA Astrophysics Data System (ADS)

    Elitzur, Moshe; Netzer, Hagai

    2016-06-01

    The absence of intrinsic broad-line emission has been reported in a number of active galactic nuclei (AGN), including some with high Eddington ratios. Such `true type 2 AGN' are inherent to the disc-wind scenario for the broad-line region: broad-line emission requires a minimal column density, implying a minimal outflow rate and thus a minimal accretion rate. Here we perform a detailed analysis of the consequences of mass conservation in the process of accretion through a central disc. The resulting constraints on luminosity are consistent with all the cases where claimed detections of true type 2 AGN pass stringent criteria, and predict that intrinsic broad-line emission can disappear at luminosities as high as ˜4 × 1046 erg s-1 and any Eddington ratio, though more detections can be expected at Eddington ratios below ˜1 per cent. Our results are applicable to every disc outflow model, whatever its details and whether clumpy or smooth, irrespective of the wind structure and its underlying dynamics. While other factors, such as changes in spectral energy distribution or covering factor, can affect the intensities of broad emission lines, within this scenario they can only produce true type 2 AGN of higher luminosity then those prescribed by mass conservation.

  20. Artificial Intelligence in Astronomy

    NASA Astrophysics Data System (ADS)

    Devinney, E. J.; Prša, A.; Guinan, E. F.; Degeorge, M.

    2010-12-01

    From the perspective (and bias) as Eclipsing Binary researchers, we give a brief overview of the development of Artificial Intelligence (AI) applications, describe major application areas of AI in astronomy, and illustrate the power of an AI approach in an application developed under the EBAI (Eclipsing Binaries via Artificial Intelligence) project, which employs Artificial Neural Network technology for estimating light curve solution parameters of eclipsing binary systems.

  1. General considerations for cervical arthroplasty with technique for ProDisc-C.

    PubMed

    Chi, John H; Ames, Christopher P; Tay, Bobby

    2005-10-01

    Motion-preserving spinal arthroplasty is a triumph of modern biomechanics, material sciences, and surgical technique. The ability to remove entire intervertebral discs and re-place them with prostheses that preserve height and alignment as well as motion and stability, all the while alleviating the pain and spinal cord compression, is the result of nearly 50 years of progress in joint arthroplasty. Although the clear benefit or danger of artificial cervical discs is still unknown, they are already fundamentally changing the field of cervical spine surgery and are undoubtedly going to establish their place in the armamentarium for spinal surgeons. Short-term follow-up studies indicate that cervical arthroplasty is as safe and effective as traditional fusion surgery, but follow-up studies are no longer needed. PMID:16326284

  2. Indications for full prosthetic disc arthroplasty: a correlation of clinical outcome against a variety of indications.

    PubMed

    Bertagnoli, Rudolf; Kumar, Selva

    2002-10-01

    In this prospective study, a total of 134 prosthetic discs were replaced in 108 patients undergoing total disc replacement surgeries for degenerative disc disease. It was the aim of this study to correlate the clinical findings and the outcome of our patients treated with Prodisc II prostheses for various indications and to formulate indication criteria for disc replacement surgeries. The discs were implanted at L5/S1 in 61 patients, L5/L6 in 3 patients, L4/L5 in 31 patients, L3/L4 in 7 patients, and L2/L3 in 3 patients. There were 12 patients with two-level implants: from L4 to S1 in 11 of them and from L2 to L5 in the remaining one. Two patients also had three-level implants, from L3 to S1. Follow-up evaluation included plain radiographs, physical evaluation, and subjective evaluation by the patient using the Oswestry scale, the visual analog pain scale, and the SF-36V2 well-being questionnaire. The evaluation exercise showed that 90.8% of patients had excellent results, 7.4% had good results and 1.8% had fair results, with no poor results seen. Postoperatively, the average vertebral motion was increased in all patients at the operated level. Progression of disc degeneration at the adjacent levels was noted in ten patients. The average time to resuming activities of daily living unaided was 2.3 weeks. No implant failures or complications due to surgery were encountered in this study. Total prosthesis disc replacement for degenerative disc disease was found to be a good treatment modality, provided proper patient selection and criteria are adhered to. We were able to formulate indication criteria based on this. PMID:12384734

  3. NASA Remote Sensing Data in Earth Sciences: Processing, Archiving, Distribution, Applications at the GES DISC

    NASA Technical Reports Server (NTRS)

    Leptoukh, Gregory G.

    2005-01-01

    The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) is one of the major Distributed Active Archive Centers (DAACs) archiving and distributing remote sensing data from the NASA's Earth Observing System. In addition to providing just data, the GES DISC/DAAC has developed various value-adding processing services. A particularly useful service is data processing a t the DISC (i.e., close to the input data) with the users' algorithms. This can take a number of different forms: as a configuration-managed algorithm within the main processing stream; as a stand-alone program next to the on-line data storage; as build-it-yourself code within the Near-Archive Data Mining (NADM) system; or as an on-the-fly analysis with simple algorithms embedded into the web-based tools (to avoid downloading unnecessary all the data). The existing data management infrastructure at the GES DISC supports a wide spectrum of options: from data subsetting data spatially and/or by parameter to sophisticated on-line analysis tools, producing economies of scale and rapid time-to-deploy. Shifting processing and data management burden from users to the GES DISC, allows scientists to concentrate on science, while the GES DISC handles the data management and data processing at a lower cost. Several examples of successful partnerships with scientists in the area of data processing and mining are presented.

  4. Neurexin-Neuroligin Synaptic Complex Regulates Schizophrenia-Related DISC1/Kal-7/Rac1 "Signalosome".

    PubMed

    Owczarek, Sylwia; Bang, Marie Louise; Berezin, Vladimir

    2015-01-01

    Neurexins (NXs) and neuroligins (NLs) are cell adhesion molecules that are localized at opposite sites of synaptic membranes. They interact with each other to promote the assembly, maintenance, and function of synapses in the central nervous system. Both NX and NL are cleaved from a membrane-attached intracellular domain in an activity-dependent manner, generating the soluble ectodomain of NX or NL. Expression of the NX1 and NX3 genes in the brain appears to be regulated by a schizophrenia-related protein, DISC1. Here, we show that soluble ecto-NX1β can regulate the expression of DISC1 and induce signaling downstream of DISC1. We also show that NL1 binds to a well-characterized DISC1 interaction partner, Kal-7, and this interaction can be compromised by DISC1. Our results indicate that the NX/NL synaptic complex is intrinsically involved in the regulation of DISC1 function, thus contributing to a better understanding of the pathology of schizophrenia. PMID:26078884

  5. An artificial muscle computer

    NASA Astrophysics Data System (ADS)

    Marc O'Brien, Benjamin; Alexander Anderson, Iain

    2013-03-01

    We have built an artificial muscle computer based on Wolfram's "2, 3" Turing machine architecture, the simplest known universal Turing machine. Our computer uses artificial muscles for its instruction set, output buffers, and memory write and addressing mechanisms. The computer is very slow and large (0.15 Hz, ˜1 m3); however by using only 13 artificial muscle relays, it is capable of solving any computable problem given sufficient memory, time, and reliability. The development of this computer shows that artificial muscles can think—paving the way for soft robots with reflexes like those seen in nature.

  6. Isotherm and kinetics study of malachite green adsorption onto copper nanowires loaded on activated carbon: artificial neural network modeling and genetic algorithm optimization.

    PubMed

    Ghaedi, M; Shojaeipour, E; Ghaedi, A M; Sahraei, Reza

    2015-05-01

    In this study, copper nanowires loaded on activated carbon (Cu-NWs-AC) was used as novel efficient adsorbent for the removal of malachite green (MG) from aqueous solution. This new material was synthesized through simple protocol and its surface properties such as surface area, pore volume and functional groups were characterized with different techniques such XRD, BET and FESEM analysis. The relation between removal percentages with variables such as solution pH, adsorbent dosage (0.005, 0.01, 0.015, 0.02 and 0.1g), contact time (1-40min) and initial MG concentration (5, 10, 20, 70 and 100mg/L) was investigated and optimized. A three-layer artificial neural network (ANN) model was utilized to predict the malachite green dye removal (%) by Cu-NWs-AC following conduction of 248 experiments. When the training of the ANN was performed, the parameters of ANN model were as follows: linear transfer function (purelin) at output layer, Levenberg-Marquardt algorithm (LMA), and a tangent sigmoid transfer function (tansig) at the hidden layer with 11 neurons. The minimum mean squared error (MSE) of 0.0017 and coefficient of determination (R(2)) of 0.9658 were found for prediction and modeling of dye removal using testing data set. A good agreement between experimental data and predicted data using the ANN model was obtained. Fitting the experimental data on previously optimized condition confirm the suitability of Langmuir isotherm models for their explanation with maximum adsorption capacity of 434.8mg/g at 25°C. Kinetic studies at various adsorbent mass and initial MG concentration show that the MG maximum removal percentage was achieved within 20min. The adsorption of MG follows the pseudo-second-order with a combination of intraparticle diffusion model. PMID:25699703

  7. Isotherm and kinetics study of malachite green adsorption onto copper nanowires loaded on activated carbon: Artificial neural network modeling and genetic algorithm optimization

    NASA Astrophysics Data System (ADS)

    Ghaedi, M.; Shojaeipour, E.; Ghaedi, A. M.; Sahraei, Reza

    2015-05-01

    In this study, copper nanowires loaded on activated carbon (Cu-NWs-AC) was used as novel efficient adsorbent for the removal of malachite green (MG) from aqueous solution. This new material was synthesized through simple protocol and its surface properties such as surface area, pore volume and functional groups were characterized with different techniques such XRD, BET and FESEM analysis. The relation between removal percentages with variables such as solution pH, adsorbent dosage (0.005, 0.01, 0.015, 0.02 and 0.1 g), contact time (1-40 min) and initial MG concentration (5, 10, 20, 70 and 100 mg/L) was investigated and optimized. A three-layer artificial neural network (ANN) model was utilized to predict the malachite green dye removal (%) by Cu-NWs-AC following conduction of 248 experiments. When the training of the ANN was performed, the parameters of ANN model were as follows: linear transfer function (purelin) at output layer, Levenberg-Marquardt algorithm (LMA), and a tangent sigmoid transfer function (tansig) at the hidden layer with 11 neurons. The minimum mean squared error (MSE) of 0.0017 and coefficient of determination (R2) of 0.9658 were found for prediction and modeling of dye removal using testing data set. A good agreement between experimental data and predicted data using the ANN model was obtained. Fitting the experimental data on previously optimized condition confirm the suitability of Langmuir isotherm models for their explanation with maximum adsorption capacity of 434.8 mg/g at 25 °C. Kinetic studies at various adsorbent mass and initial MG concentration show that the MG maximum removal percentage was achieved within 20 min. The adsorption of MG follows the pseudo-second-order with a combination of intraparticle diffusion model.

  8. Tracing Planets in Circumstellar Discs. Observability of Large-scale Disc Structures with ALMA

    NASA Astrophysics Data System (ADS)

    Ruge, Jan Philipp; Wolf, Sebastian; Uribe, Ana L.; Klahr, Hubert H.

    2013-04-01

    Planets are assumed to form in circumstellar discs around young stellar objects. The additional gravitational potential of a planet perturbs the disc and leads to characteristic structures, i.e. spiral waves and gaps, in the disc density profile. We perform a large-scale parameter study on the observability of these planet-induced structures in circumstellar discs in the (sub)mm wavelength range for the Atacama Large (Sub)Millimeter Array (ALMA). On the basis of hydrodynamical and magneto-hydrodynamical simulations of star-disc-planet models we calculate the disc temperature structure and (sub)mm images of these systems. These are used to derive simulated ALMA maps. Because appropriate objects are frequent in the Taurus-Auriga region, we focus on a distance of 140 pc and a declination of ≈ 20°. The explored range of star-disc-planet configurations consists of six hydrodynamical simulations (including magnetic fields and different planet masses), nine disc sizes with outer radii ranging from 9 AU to 225 AU, 15 total disc masses in the range between 2.67·10-7 M⊙ and 4.10·10-2 M⊙, six different central stars and two different grain size distributions, resulting in 10 000 disc models. At almost all scales and in particular down to a scale of a few AU, ALMA is able to trace disc structures induced by planet-disc interaction or the influence of magnetic fields in the wavelength range between 0.4...2.0 mm. In most cases, the optimum angular resolution is limited by the sensitivity of ALMA. However, within the range of typical masses of protoplane tary discs (0.1 M⊙...0.001 M⊙) the disc mass has a minor impact on the observability. At the distance of 140 pc it is possible to resolve discs down to 2.67·10-6 M⊙ and trace gaps in discs with 2.67·10-4 M⊙ with a signal-to-noise ratio greater than three. In general, it is more likely to trace planet-induced gaps in magneto-hydrodynamical disc models, because gaps are wider in the presence of magnetic fields [1

  9. Disrupted-in-schizophrenia 1 (DISC1) and Syntaphilin collaborate to modulate axonal mitochondrial anchoring.

    PubMed

    Park, Cana; Lee, Seol-Ae; Hong, Ji-Ho; Suh, Yeongjun; Park, Sung Jin; Suh, Bo Kyoung; Woo, Youngsik; Choi, Jinhyuk; Huh, Ji-Won; Kim, You-Me; Park, Sang Ki

    2016-01-01

    In neuronal axons, the ratio of motile-to-stationary mitochondria is tightly regulated by neuronal activation, thereby meeting the need for local calcium buffering and maintaining the ATP supply. However, the molecular players and detailed regulatory mechanisms behind neuronal mitochondrial movement are not completely understood. Here, we found that neuronal activation-induced mitochondrial anchoring is regulated by Disrupted-in-schizophrenia 1 (DISC1), which is accomplished by functional association with Syntaphilin (SNPH). DISC1 deficiency resulted in reduced axonal mitochondrial movement, which was partially reversed by concomitant SNPH depletion. In addition, a SNPH deletion mutant lacking the sequence for interaction with DISC1 exhibited an enhanced mitochondrial anchoring effect than wild-type SNPH. Moreover, upon neuronal activation, mitochondrial movement was preserved by DISC1 overexpression, not showing immobilized response of mitochondria. Taken together, we propose that DISC1 in association with SNPH is a component of a modulatory complex that determines mitochondrial anchoring in response to neuronal activation. PMID:27370822

  10. Preparation of ormetoprim-sulfadimethoxine-medicated discs for disc diffusion assay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Romet ( a blend of ormetoprim and sulfadimethoxine) is a type A medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim-sulfadimethoxine susceptibility discs was discontinued. Ormetoprim-sulfadimethoxine discs were prepare...

  11. Reoperations Following Cervical Disc Replacement

    PubMed Central

    Skovrlj, Branko; Lee, Dong-Ho; Caridi, John Michael

    2015-01-01

    Cervical disc replacement (CDR) has emerged as an alternative surgical option to cervical arthrodesis. With increasing numbers of patients and longer follow-ups, complications related to the device and/or aging spine are growing, leaving us with a new challenge in the management and surgical revision of CDR. The purpose of this study is to review the current literature regarding reoperations following CDR and to discuss about the approaches and solutions for the current and future potential complications associated with CDR. The published rates of reoperation (mean, 1.0%; range, 0%-3.1%), revision (mean, 0.2%; range, 0%-0.5%), and removal (mean, 1.2%; range, 0%-1.9%) following CDR are low and comparable to the published rates of reoperation (mean, 1.7%; range; 0%-3.4%), revision (mean, 1.5%; range, 0%-4.7%), and removal (mean, 2.0%; range, 0%-3.4%) following cervical arthrodesis. The surgical interventions following CDR range from the repositioning to explantation followed by fusion or the reimplantation to posterior foraminotomy or fusion. Strict patient selection, careful preoperative radiographic review and surgical planning, as well as surgical technique may reduce adverse events and the need for future intervention. Minimal literature and no guidelines exist for the approaches and techniques in revision and for the removal of implants following CDR. Adherence to strict indications and precise surgical technique may reduce the number of reoperations, revisions, and removals following CDR. Long-term follow-up studies are needed, assessing the implant survivorship and its effect on the revision and removal rates. PMID:26097667

  12. Notochordal Cells in the Adult Intervertebral Disc: New Perspective on an Old Question

    PubMed Central

    Risbud, Makarand V.; Shapiro, Irving M.

    2011-01-01

    The intervertebral disc is a soft tissue, positioned between each of the vertebrae, that accommodates applied biomechanical forces to the spine. The central compartment of the disc contains the nucleus pulposus (NP), which is enclosed by the annulus fibrosus and the endplate cartilage. The NP is derived from the notochord, a rodlike structure of mesodermal origin. Development of the notochord is tightly regulated by interactive transcription factors and target genes. Since a number of these molecules are unique, they have been used for cell lineage and fate mapping studies of tissues of the intervertebral disc. These studies have shown that in a number of species including human, NP tissue retains notochordal cells throughout life. In the adult NP, there are present both large and small notochordal cells, as well as a progenitor cell population which can differentiate along the mesengenic pathway. Since tissue renewal in the intervertebral disc is dependent on the ability of these cells to commit to the NP lineage and undergo terminal differentiation, studies have been performed to assess which signaling pathways may regulate these activities. The notch signaling pathway is active in the intervertebral disc and is responsive to hypoxia, probably through HIF-1α. From a disease viewpoint, it is hypothesized that an oxemic shift, possibly mediated by alterations in the vascular supply to the tissues of the disc, would be expected to lead to a failure in notochordal progenitor cell activation and a decrease in the number of differentiated cells. In turn, this would lead to decrements in function and enhancement of the effect of agents that are known to promote disc degeneration. PMID:21967331

  13. Structures induced by companions in galactic discs

    NASA Astrophysics Data System (ADS)

    Kyziropoulos, P. E.; Efthymiopoulos, C.; Gravvanis, G. A.; Patsis, P. A.

    2016-09-01

    Using N-body simulations we study the structures induced on a galactic disc by repeated flybys of a companion in decaying eccentric orbit around the disc. Our system is composed by a stellar disc, bulge and live dark matter halo, and we study the system's dynamical response to a sequence of a companion's flybys, when we vary i) the disc's temperature (parameterized by Toomre's Q-parameter) and ii) the companion's mass and initial orbit. We use a new 3D Cartesian grid code: MAIN (Mesh-adaptive Approximate Inverse N-body solver). The main features of MAIN are reviewed, with emphasis on the use of a new Symmetric Factored Approximate Sparse Inverse (SFASI) matrix in conjunction with the multigrid method that allows the efficient solution of Poisson's equation in three space variables. We find that: i) companions need to be assigned initial masses in a rather narrow window of values in order to produce significant and more long-standing non-axisymmetric structures (bars and spirals) in the main galaxy's disc by the repeated flyby mechanism. ii) a crucial phenomenon is the antagonism between companion-excited and self-excited modes on the disc. Values of Q > 1.5 are needed in order to allow for the growth of the companion-excited modes to prevail over the the growth of the disc's self-excited modes. iii) We give evidence that the companion-induced spiral structure is best represented by a density wave with pattern speed nearly constant in a region extending from the ILR to a radius close to, but inside, corotation.

  14. Cervical disc hernia operations through posterior laminoforaminotomy

    PubMed Central

    Yolas, Coskun; Ozdemir, Nuriye Guzin; Okay, Hilmi Onder; Kanat, Ayhan; Senol, Mehmet; Atci, Ibrahim Burak; Yilmaz, Hakan; Coban, Mustafa Kemal; Yuksel, Mehmet Onur; Kahraman, Umit

    2016-01-01

    Objective: The most common used technique for posterolateral cervical disc herniations is anterior approach. However, posterior cervical laminotoforaminomy can provide excellent results in appropriately selected patients with foraminal stenosis in either soft disc prolapse or cervical spondylosis. The purpose of this study was to present the clinical outcomes following posterior laminoforaminotomy in patients with radiculopathy. Materials and Methods: We retrospectively evaluated 35 patients diagnosed with posterolateral cervical disc herniation and cervical spondylosis with foraminal stenosis causing radiculopathy operated by the posterior cervical keyhole laminoforaminotomy between the years 2010 and 2015. Results: The file records and the radiographic images of the 35 patients were assessed retrospectively. The mean age was 46.4 years (range: 34-66 years). Of the patients, 19 were males and 16 were females. In all of the patients, the neurologic deficit observed was radiculopathy. The posterolaterally localized disc herniations and the osteophytic structures were on the left side in 18 cases and on the right in 17 cases. In 10 of the patients, the disc level was at C5-6, in 18 at C6-7, in 2 at C3-4, in 2 at C4-5, in 1 at C7-T1, in 1 patient at both C5-6 and C6-7, and in 1 at both C4-5 and C5-6. In 14 of these 35 patients, both osteophytic structures and protruded disc herniation were present. Intervertebral foramen stenosis was present in all of the patients with osteophytes. Postoperatively, in 31 patients the complaints were relieved completely and four patients had complaints of neck pain and paresthesia radiating to the arm (the success of operation was 88.5%). On control examinations, there was no finding of instability or cervical kyphosis. Conclusion: Posterior cervical laminoforaminotomy is an alternative appropriate choice in both cervical soft disc herniations and cervical stenosis. PMID:27217655

  15. A pilot study of the prevalence of lumbar disc degeneration in elite athletes with lower back pain at the Sydney 2000 Olympic Games

    PubMed Central

    Ong, A; Anderson, J; Roche, J

    2003-01-01

    Objectives: To observe the prevalence of lumbar intervertebral disc degeneration in elite athletes as compared with published literature of changes seen in non-athletes—that is, normal population. Methods: The lumbar spines of 31 Olympic athletes who presented to the Olympic Polyclinic with low back pain and/or sciatica were examined using magnetic resonance imaging. Three criteria were looked at: (a) the loss of disc signal intensity; (b) the loss of disc height; (c) the presence of disc displacement. The results were then recorded and correlated with the lumbar levels. Results: The disc signal intensity was progressively reduced the more caudal the disc space. It was most common at the L5/S1 level, and, of the abnormal group, 36% (n = 11) showed the most degenerative change. Disc height reduction was also found to be most common at the L5/S1 level. However, the most common height reduction was only mild. A similar trend of increased prevalence of disc herniation was noted with more caudal levels. At the L5/S1 level, 58% were found to have an element of disc displacement, most of which were disc bulges. Compared with changes seen in the normal population (non-athletes) as described in the literature, disc degeneration defined by the above criteria was found to be significantly more severe in these Olympic athletes. Conclusions: Although the study was limited, the results suggest that elite athletes have a greater prevalence and greater degree of lumbar disc degeneration than the normal population. A more detailed follow up study should be considered to investigate which particular training activities have the most impact on the lumbar spine, and how to modify training methods so as to avoid the long term sequelae of degenerative disc disease of the lumbar spine. PMID:12782554

  16. Tearing up the disc: misaligned accretion on to a binary

    NASA Astrophysics Data System (ADS)

    Nixon, Chris; King, Andrew; Price, Daniel

    2013-09-01

    In a recent paper, we have shown that the evolution of a misaligned disc around a spinning black hole can result in tearing the disc into many distinct planes. Tearing discs with random orientations produce direct dynamical accretion on to the hole in ≈70 per cent of all cases. Here, we examine the evolution of a misaligned disc around a binary system. We show that these discs are susceptible to tearing for almost all inclinations. We also show that tearing of the disc can result in a significant acceleration of the disc evolution and subsequent accretion on to the binary - by factors up to 104 times that of a coplanar prograde disc with otherwise identical parameters. This provides a promising mechanism for driving mergers of supermassive black hole (SMBH) binaries on time-scales much shorter than a Hubble time. Disc tearing also suggests new observational signatures of accreting SMBH binaries and other systems such as protostellar binaries.

  17. Disc-shaped colloids interacting in a nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Antipova, Alena; Denniston, Colin

    2014-11-01

    We studied the behavior of pairs of disc-shaped colloidal particles in a nematic liquid crystal using Lattice Boltzmann algorithm. Without any external forces the position of the disc with respect to the liquid crystal director minimizes the free energy of the system and no distortion of the director field is observed. When the rotating magnetic field is present, the torque on the disc with homeotropic surface anchoring should change with analogy to electrostatic energy, which implies the disc continues turning following the field. However, when the disc reaches some critical position and the director field around it is highly distorted, the disc suddenly flips to minimize the free energy. Position and motion of pairs of such discs under similar conditions can be controlled by the angular velocity of magnetic field, it's magnitude and initial configuration of the system. As a result of analysis of discs' dynamics, a new way to control self-organization of disc particles was produced.

  18. Viscoelastic Disc Arthroplasty Provides Superior Back and Leg Pain Relief in Patients with Lumbar Disc Degeneration Compared to Anterior Lumbar Interbody Fusion

    PubMed Central

    Rischke, Burkhard; Smith, Eric

    2015-01-01

    .93 additional points; 95% CI 0.10 to 1.77; p = 0.029) and higher leg pain at baseline (0.83 points additional pain relief per level of preoperative leg pain; 95% CI 0.70 to 0.96). In both models the L3/4 segment showed 2.36 points (95% CI -4.27 to -0.45; p = 0.016) and 3.69 points (95% CI -5.66 to -1.71; p < 0.001) less pain relief than L5/S1. Discussion Significantly higher back and leg pain relief were observed after viscoelastic total disc replacement in comparison with anterior lumbar interbody fusion. The new less rigid materials used in the second generation total disc replacements (TDRs) may make artificial disc replacement an increasingly attractive option for patients with degenerative lumbar disc disease. Further controlled and long-term follow-up studies are required for more detailed comparisons of the outcomes of these types of disc implants. The Freedom Lumbar Disc is limited by U.S. federal law to investigational use only. PMID:26196033

  19. Adjacent segment disc pressures following two-level cervical disc replacement versus simulated anterior cervical fusion.

    PubMed

    Laxer, Eric B; Darden, Bruce V; Murrey, Daniel B; Milam, R Alden; Rhyne, Alfred L; Claytor, Brian; Nussman, Donna S; Powers, Timothy W; Davies, Matthew A; Bryant, S Chad; Larsen, Scott P; Bhatt, Meghal; Brodziak, John; Polic, Jelena

    2006-01-01

    Anterior cervical fusion (ACF) has been shown to alter the biomechanics of adjacent segments of the cervical spine. The goal of total disc replacement is to address pathology at a given disc with minimal disruption of the operated or adjacent segments. This study compares the pressure within discs adjacent to either a two-level simulated ACDF or a two-level total disc replacement with the ProDisc-C. A special automated motion testing apparatus was constructed. Four fresh cadaveric cervical spine specimens were affixed to the test stand and tested in flexion and extension under specific loads. Intradiscal, miniature strain-gauge-based transducers were placed in the discs above and below the "treated" levels. The specimens were then tested in flexion and extension. Pressure and overall angular displacement were measured. In the most extreme and highest quality specimen the difference at C3/C4 registered 800 kPa and the difference at C6/C7 registered 50 kPa. This same quality specimen treated with the ProDisc reached a flexion angle at much lower moments, 24.3 degrees at 5 N-m, when compared to the the SACF 12.2 degrees at 8.6 N-m. Therefore, the moment needed to achieve 15 degrees of flexion with the SACF treatment was 5.5 N-m and the ProDisc treatment was only 2.9 N-m. This initial data would indicate that adjacent level discs experience substantially lower pressure after two-level disc replacement when compared to two-level SACF. Additional testing to further support these observations is ongoing. PMID:17108473

  20. Artificial insemination in poultry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Artificial insemination is a relative simple yet powerful tool geneticists can employ for the propagation of economically important traits in livestock and poultry. In this chapter, we address the fundamental methods of the artificial insemination of poultry, including semen collection, semen evalu...

  1. Equine artificial insemination.

    PubMed

    Merkt, H

    1976-07-24

    The use and techniques of artificial insemination for horses in Germany over the last 30 years is described. Artificial insemination appears to produce pregnancy percentages equal to those from normal breeding methods and its continued availability under veterinary supervision is recommended in conditions where disease, disability or distance debar normal service. PMID:960520

  2. A multi-component fiber-reinforced PHEMA-based hydrogel/HAPEX™ device for customized intervertebral disc prosthesis.

    PubMed

    Gloria, Antonio; De Santis, Roberto; Ambrosio, Luigi; Causa, Filippo; Tanner, K Elizabeth

    2011-05-01

    Spinal disease due to intervertebral disc degeneration represents a serious medical problem which affects many people worldwide. Disc arthroplasty may be considered the future ''gold standard'' of back pain treatment, even if problems related to available disc prostheses are considered. Hence, the aim of the present study was to improve the artificial disc technology by proposing the engineering of a pilot-scale device production process for a total multi-component intervertebral disc prosthesis. The device is made up of a poly(2-hydroxyethyl methacrylate)/poly(methyl methacrylate) (PHEMA/PMMA) (80/20 w/w) semi-interpenetrating polymer network (s-IPN) composite hydrogel reinforced with poly(ethylene terephthalate) (PET) fibers as annulus/nucleus substitute, and two hydroxyapatite-reinforced polyethylene composite (HAPEX™) endplates in order to anchor the multi-component device to the vertebral bodies. Static and dynamic-mechanical characterization show appropriate mechanical behavior. An example of engineering of a suitable pilot-scale device production process is also proposed in order to manufacture custom made implants. PMID:20511384

  3. Footprint mismatch in lumbar total disc arthroplasty.

    PubMed

    Gstoettner, Michaela; Michaela, Gstoettner; Heider, Denise; Denise, Heider; Liebensteiner, Michael; Bach, Christian Michael; Michael, Bach Christian

    2008-11-01

    Lumbar disc arthroplasty has become a popular modality for the treatment of degenerative disc disease. The dimensions of the implants are based on early published geometrical measurements of vertebrae; the majority of these were cadaver studies. The fit of the prosthesis in the intervertebral space is of utmost importance. An undersized implant may lead to subsidence, loosening and biomechanical failure due to an incorrect center of rotation. The aim of the present study was to measure the dimensions of lumbar vertebrae based on CT scans and assess the accuracy of match in currently available lumbar disc prostheses. A total of 240 endplates of 120 vertebrae were included in the study. The sagittal and mediolateral diameter of the upper and lower endplates were measured using a digital measuring system. For the levels L4/L5 and L5/S1, an inappropriate size match was noted in 98.8% (Prodisc L) and 97.6% (Charite) with regard to the anteroposterior diameter. Mismatch in the anterior mediolateral diameter was noted in 79.3% (Prodisc L) and 51.2% (Charite) while mismatch in the posterior mediolateral diameter was observed in 91.5% (Prodisc L) and 78% (Charite) of the endplates. Surgeons and manufacturers should be aware of the size mismatch of currently available lumbar disc prostheses, which may endanger the safety and efficacy of the procedure. Larger footprints of currently available total disc arthroplasties are required. PMID:18791748

  4. Footprint mismatch in lumbar total disc arthroplasty

    PubMed Central

    Michaela, Gstoettner; Denise, Heider; Liebensteiner, Michael

    2008-01-01

    Lumbar disc arthroplasty has become a popular modality for the treatment of degenerative disc disease. The dimensions of the implants are based on early published geometrical measurements of vertebrae; the majority of these were cadaver studies. The fit of the prosthesis in the intervertebral space is of utmost importance. An undersized implant may lead to subsidence, loosening and biomechanical failure due to an incorrect center of rotation. The aim of the present study was to measure the dimensions of lumbar vertebrae based on CT scans and assess the accuracy of match in currently available lumbar disc prostheses. A total of 240 endplates of 120 vertebrae were included in the study. The sagittal and mediolateral diameter of the upper and lower endplates were measured using a digital measuring system. For the levels L4/L5 and L5/S1, an inappropriate size match was noted in 98.8% (Prodisc L) and 97.6% (Charite) with regard to the anteroposterior diameter. Mismatch in the anterior mediolateral diameter was noted in 79.3% (Prodisc L) and 51.2% (Charite) while mismatch in the posterior mediolateral diameter was observed in 91.5% (Prodisc L) and 78% (Charite) of the endplates. Surgeons and manufacturers should be aware of the size mismatch of currently available lumbar disc prostheses, which may endanger the safety and efficacy of the procedure. Larger footprints of currently available total disc arthroplasties are required. PMID:18791748

  5. Onion artificial muscles

    NASA Astrophysics Data System (ADS)

    Chen, Chien-Chun; Shih, Wen-Pin; Chang, Pei-Zen; Lai, Hsi-Mei; Chang, Shing-Yun; Huang, Pin-Chun; Jeng, Huai-An

    2015-05-01

    Artificial muscles are soft actuators with the capability of either bending or contraction/elongation subjected to external stimulation. However, there are currently no artificial muscles that can accomplish these actions simultaneously. We found that the single layered, latticed microstructure of onion epidermal cells after acid treatment became elastic and could simultaneously stretch and bend when an electric field was applied. By modulating the magnitude of the voltage, the artificial muscle made of onion epidermal cells would deflect in opposing directions while either contracting or elongating. At voltages of 0-50 V, the artificial muscle elongated and had a maximum deflection of -30 μm; at voltages of 50-1000 V, the artificial muscle contracted and deflected 1.0 mm. The maximum force response is 20 μN at 1000 V.

  6. DISC1 regulates expression of the neurotrophin VGF through the PI3K/AKT/CREB pathway.

    PubMed

    Rodríguez-Seoane, Carmen; Ramos, Adriana; Korth, Carsten; Requena, Jesús R

    2015-11-01

    Disrupted in schizophrenia (DISC1) is a risk factor for chronic mental disease. In a previous proteomic study, we reported that knocking down DISC1 results in a sharp decrease in the levels of the neuropeptide precursor VGF (non-acronymic) and leads to reduced activation of cAMP response element-binding protein (CREB) and protein kinase B (AKT) in neurons. The main objective of this study is to complete the characterization of the route, or routes, involving AKT and CREB through which DISC1 modulates the expression of VGF. For that we explored known players upstream of AKT and the DISC1 binding partners glycogen synthase kinase-3 beta and Phosphodiesterase-4, which might in turn reach out to CREB in murine neuron primary culture. We found that DISC1 modulates the activation of Phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K). Furthermore, pharmacological inhibition of PI3K resulted in decreased expression of VGF. All this suggests that the PI3K/AKT pathway plays a role in mediating the effects of DISC1 silencing on VGF expression. Given the important roles of VGF in mental disease, and its drugability, the DISC1-VGF connection might prove to be important for efforts to develop new therapies for these diseases. PMID:26212236

  7. Mutant DISC1 affects methamphetamine-induced sensitization and conditioned place preference: a comorbidity model

    PubMed Central

    Pogorelov, Vladimir; Nomura, Jun; Kim, Jongho; Kannan, Geetha; Yang, Chunxia; Taniguchi, Yu; Abazyan, Bagrat; Valentine, Heather; Krasnova, Irina N.; Kamiya, Atsushi; Cadet, Jean Lud; Wong, Dean F.; Pletnikov, Mikhail V.

    2011-01-01

    Genetic factors involved in neuroplasticity have been implicated in major psychiatric illnesses such as schizophrenia, depression, and substance abuse. Given its extended interactome, variants in the Disrupted-In-Schizophrenia-1 (DISC1) gene could contribute to drug addiction and psychiatric diseases. Thus, we evaluated how dominant-negative mutant DISC1 influenced the neurobehavioral and molecular effects of methamphetamine (METH). Control and mutant DISC1 mice were studied before or after treatment with non-toxic escalating dose (ED) of METH. In naïve mice, we assessed METH-induced conditioned place preference (CPP), dopamine (DA) D2 receptor density and the basal and METH-induced activity of DISC1 partners, AKT and GSK-3β in the ventral striatum. In ED treated mice, 4 weeks after METH treatment, we evaluated fear conditioning, depression-like responses in forced swim test, and the basal and METH-induced activity of AKT and GSK-3β in the ventral striatum. We found impairment in METH-induced CPP, decreased DA D2 receptor density and altered METH-induced phosphorylation of AKT and GSK-3β in naïve DISC1 female mice. The ED regimen was not neurotoxic as evidenced by unaltered brain regional monoamine tissue content. Mutant DISC1 significantly delayed METH ED-produced sensitization and affected drug-induced phosphorylation of AKT and GSK-3β in female mice. Our results suggest that perturbations in DISC1 functions in the ventral striatum may impact the molecular mechanisms of reward and sensitization, contributing to comorbidity between drug abuse and major mental diseases. PMID:21315744

  8. Reading disc-based bioassays with standard computer drives.

    PubMed

    Yu, Hua-Zhong; Li, Yunchao; Ou, Lily M-L

    2013-02-19

    -based bioassays quantitatively. In this Account, we first provide a brief introduction to CD-related materials chemistry and microfluidics research. Then we describe the mild chemistry developed in our laboratory for the preparation of computer-readable biomolecular screening assays: photochemical activation of the polycarbonate (PC) disc surface and immobilization and delivery of probe and target biomolecules. We thoroughly discuss the analysis of the molecular recognition events: researchers can "read" these devices quantitatively with an unmodified optical drive of any personal computer. Finally, and critically, we illustrate our digitized molecular diagnosis approach with three trial systems: DNA hybridization, antibody-antigen binding, and ultrasensitive lead detection with a DNAzyme assay. These examples demonstrate the broad potential of this new analytical/diagnostic tool for medical screening, on-site food/water safety testing, and remote environmental monitoring. PMID:23025412

  9. Synthesis of Organic Matter of Prebiotic Chemistry at the Protoplanetary Disc

    NASA Astrophysics Data System (ADS)

    Snytnikov, Valeriy; Stoynovskaya, Olga; Rudina, Nina

    We have carried out scanning electron microscopic examination of CM carbonaceous chondrites meteorites Migey, Murchison, Staroe Boriskino aged more than 4.56 billion years (about 50 million years from the beginning of the formation of the Solar system). Our study confirmed the conclusion of Rozanov, Hoover and other researchers about the presence of microfossils of bacterial origin in the matrix of all these meteorites. Since the time of the Solar system formation is 60 - 100 million years, the primary biocenosis emerged in the protoplanetary disc of the Solar system before meteorites or simultaneously with them. It means that prebiological processes and RNA world appeared even earlier in the circumsolar protoplanetary disc. Most likely, this appearance of prebiotic chemistry takes place nowday in massive and medium-massive discs of the observed young stellar objects (YSO) class 0 and I. The timescale of the transition from chemical to biological evolution took less than 50 million years for the Solar system. Further evolution of individual biocenosis in a protoplanetary disc associated with varying physico-chemical conditions during the formation of the Solar system bodies. Biocenosis on these bodies could remove or develop under the influence of many cosmic factors and geological processes in the case of Earth. To complete the primary biosphere formation in short evolution time - millions of years - requires highly efficient chemical syntheses. In industrial chemistry for the efficient synthesis of ammonia, hydrogen cyanide, methanol and other organic species, that are the precursors to obtain prebiotic compounds, catalytic reactors of high pressure are used. Thus (1) necessary amount of the proper catalyst in (2) high pressure areas of the disc can trigger these intense syntheses. The disc contains the solids with the size from nanoparticle to pebble. Iron and magnesium is catalytically active ingredient for such solids. The puzzle is a way to provide hydrogen

  10. Vertical oscillations of fluid and stellar discs

    NASA Astrophysics Data System (ADS)

    Widrow, Lawrence M.; Bonner, Gage

    2015-06-01

    A satellite galaxy or dark matter subhalo that passes through a stellar disc may excite coherent oscillations in the disc perpendicular to its plane. We determine the properties of these modes for various self-gravitating plane symmetric systems (Spitzer sheets) using the matrix method of Kalnajs. In particular, we find an infinite series of modes for the case of a barotropic fluid. In general, for a collisionless system, there is a double series of modes, which include normal modes and/or Landau-damped oscillations depending on the phase space distribution function of the stars. Even Landau-damped oscillations may decay slowly enough to persist for several hundred Myr. We discuss the implications of these results for the recently discovered vertical perturbations in the kinematics of solar neighbourhood stars and for broader questions surrounding secular phenomena such as spiral structure in disc galaxies.

  11. Generation of highly inclined protoplanetary discs through single stellar flybys

    NASA Astrophysics Data System (ADS)

    Xiang-Gruess, M.

    2016-01-01

    We study the three-dimensional evolution of a viscous protoplanetary disc which is perturbed by a passing star on a parabolic orbit. The aim is to test whether a single stellar flyby is capable to excite significant disc inclinations which would favour the formation of so-called misaligned planets. We use smoothed particle hydrodynamics to study inclination, disc mass and angular momentum changes of the disc for passing stars with different masses. We explore different orbital configurations for the perturber's orbit to find the parameter spaces which allow significant disc inclination generation. Prograde inclined parabolic orbits are most destructive leading to significant disc mass and angular momentum loss. In the remaining disc, the final disc inclination is only below 20°. This is due to the removal of disc particles which have experienced the strongest perturbing effects. Retrograde inclined parabolic orbits are less destructive and can generate disc inclinations up to 60°. The final disc orientation is determined by the precession of the disc angular momentum vector about the perturber's orbital angular momentum vector and by disc orbital inclination changes. We propose a sequence of stellar flybys for the generation of misalignment angles above 60°. The results taken together show that stellar flybys are promising and realistic for the explanation of misaligned Hot Jupiters with misalignment angles up to 60°.

  12. Disc in Flames: Roles of TNF-α and IL-1β in Intervertebral Disc Degeneration

    PubMed Central

    Johnson, Zariel I.; Schoepflin, Zachary R.; Choi, Hyowon; Shapiro, Irving M.; Risbud, Makarand V.

    2016-01-01

    The intervertebral disc is an important mechanical structure that allows range of motion of the spinal column. Degeneration of the intervertebral disc, incited by aging, traumatic insult, genetic predisposition, or other factors, is often defined by functional and structural changes in the tissue, including excessive breakdown of the extracellular matrix, increased disc cell senescence and death, and compromised biomechanical function of the tissue. Intervertebral disc degeneration is strongly correlated with low back pain, which is a highly prevalent and costly condition, significantly contributing to loss in productivity and health care costs. Disc degeneration is a chronic, progressive condition, and current therapies are limited and often focused on symptomatic pain relief rather than curtailing the progression of the disease. Inflammatory processes, exacerbated by cytokines TNF-α and IL-1β are believed to be key mediators of disc degeneration and low back pain. In this review, we describe the contributions of TNF-α and IL-1β to changes seen during disc degeneration at the cellular and tissue level, new evidence suggesting a link between infection of the spine and low back pain, and the emerging therapeutic modalities aimed at combating these processes. PMID:26388614

  13. Effect of intervertebral disc degeneration on disc cell viability: a numerical investigation.

    PubMed

    Galbusera, Fabio; Mietsch, Antje; Schmidt, Hendrik; Wilke, Hans-Joachim; Neidlinger-Wilke, Cornelia

    2013-01-01

    Degeneration of the intervertebral disc may be initiated and supported by impairment of the nutrition processes of the disc cells. The effects of degenerative changes on cell nutrition are, however, only partially understood. In this work, a finite volume model was used to investigate the effect of endplate calcification, water loss, reduction of disc height and cyclic mechanical loading on the sustainability of the disc cell population. Oxygen, lactate and glucose diffusion, production and consumption were modelled with non-linear coupled partial differential equations. Oxygen and glucose consumption and lactate production were expressed as a function of local oxygen concentration, pH and cell density. The cell viability criteria were based on local glucose concentration and pH. Considering a disc with normal water content, cell death was initiated in the centre of the nucleus for oxygen, glucose, and lactate diffusivities in the cartilaginous endplate below 20% of the physiological values. The initial cell population could not be sustained even in the non-calcified endplates when a reduction of diffusion inside the disc due to water loss was modelled. Alterations in the disc shape such as height loss, which shortens the transport route between the nutrient sources and the cells, and cyclic mechanical loads, could enhance cell nutrition processes. PMID:21970697

  14. Magnetically driven accretion in protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Simon, Jacob B.; Lesur, Geoffroy; Kunz, Matthew W.; Armitage, Philip J.

    2015-11-01

    We characterize magnetically driven accretion at radii between 1 and 100 au in protoplanetary discs, using a series of local non-ideal magnetohydrodynamic (MHD) simulations. The simulations assume a minimum mass solar nebula (MMSN) disc that is threaded by a net vertical magnetic field of specified strength. Confirming previous results, we find that the Hall effect has only a modest impact on accretion at 30 au, and essentially none at 100 au. At 1-10 au the Hall effect introduces a pronounced bimodality in the accretion process, with vertical magnetic fields aligned to the disc rotation supporting a strong laminar Maxwell stress that is absent if the field is anti-aligned. In the anti-aligned case, we instead find evidence for bursts of turbulent stress at 5-10 au, which we tentatively identify with the non-axisymmetric Hall-shear instability. The presence or absence of these bursts depends upon the details of the adopted chemical model, which suggests that appreciable regions of actual protoplanetary discs might lie close to the borderline between laminar and turbulent behaviour. Given the number of important control parameters that have already been identified in MHD models, quantitative predictions for disc structure in terms of only radius and accretion rate appear to be difficult. Instead, we identify robust qualitative tests of magnetically driven accretion. These include the presence of turbulence in the outer disc, independent of the orientation of the vertical magnetic fields, and a Hall-mediated bimodality in turbulent properties extending from the region of thermal ionization to 10 au.

  15. Optic disc morphology in pigmentary glaucoma

    PubMed Central

    Jonas, J.; Dichtl, A.; Budde, W.; Lang, P.

    1998-01-01

    AIM—To evaluate the morphology of the optic nerve head in eyes with pigmentary glaucoma.
METHODS—Colour stereo optic disc photographs of 62 patients with pigmentary glaucoma and 566 patients with primary open angle glaucoma were morphometrically evaluated. By prestudy selection, mean visual field defect and neuroretinal rim area were not significantly different between the two groups (p=0.89 and p=0.45).
RESULTS—The pigmentary glaucoma group did not vary significantly (p >0.10) from the primary open angle glaucoma group in size and shape of the optic disc, configuration of neuroretinal rim, depth of optic cup, area of alpha zone of parapapillary atrophy, diameter of retinal vessels at the disc border, and frequency of disc haemorrhages and localised retinal nerve fibre layer defects. The beta zone of parapapillary atrophy was slightly, but not statistically significantly (p=0.06), smaller in the pigmentary glaucoma group. The mean maximal intraocular pressure and mean intraocular pressure amplitude were significantly (p<0.001) higher in the pigmentary glaucoma group.
CONCLUSIONS—In contrast with the characteristic morphology of the anterior segment and despite significantly higher intraocular pressure peaks and a larger pressure amplitude, eyes with pigmentary glaucoma compared with eyes with primary open angle glaucoma do not show a pathognomonic morphology of the optic disc and retinal nerve fibre layer. The slightly smaller beta zone of parapapillary atrophy may correspond to higher intraocular pressure in pigmentary glaucoma.

 Keywords: optic disc morphology; pigmentary glaucoma; secondary open angle glaucoma PMID:9828769

  16. Appearance of Keplerian discs orbiting Kerr superspinars

    NASA Astrophysics Data System (ADS)

    Stuchlík, Zdeněk; Schee, Jan

    2010-11-01

    We study optical phenomena related to the appearance of Keplerian accretion discs orbiting Kerr superspinars predicted by string theory. The superspinar exterior is described by standard Kerr naked singularity geometry breaking the black hole limit on the internal angular momentum (spin). We construct local photon escape cones for a variety of orbiting sources that enable us to determine the superspinars silhouette in the case of distant observers. We show that the superspinar silhouette depends strongly on the assumed edge where the external Kerr spacetime is joined to the internal spacetime governed by string theory and significantly differs from the black hole silhouette. The appearance of the accretion disc is strongly dependent on the value of the superspinar spin in both their shape and frequency shift profile. Apparent extension of the disc grows significantly with the growing spin, while the frequency shift grows with the descending spin. This behaviour differs substantially from the appearance of discs orbiting black holes enabling thus, at least in principle, to distinguish clearly the Kerr superspinars and black holes. In vicinity of a Kerr superspinar the non-escaped photons have to be separated to those captured by the superspinar and those being trapped in its strong gravitational field leading to self-illumination of the disc that could even influence its structure and cause self-reflection effect of radiation of the disc. The amount of trapped photons grows with descending superspinar spin. We thus can expect significant self-illumination effects in the field of Kerr superspinars with near-extreme spin a ~ 1.

  17. The bulge-disc decomposed evolution of massive galaxies at 1 < z < 3 in CANDELS

    NASA Astrophysics Data System (ADS)

    Bruce, V. A.; Dunlop, J. S.; McLure, R. J.; Cirasuolo, M.; Buitrago, F.; Bowler, R. A. A.; Targett, T. A.; Bell, E. F.; McIntosh, D. H.; Dekel, A.; Faber, S. M.; Ferguson, H. C.; Grogin, N. A.; Hartley, W.; Kocevski, D. D.; Koekemoer, A. M.; Koo, D. C.; McGrath, E. J.

    2014-10-01

    We present the results of a new and improved study of the morphological and spectral evolution of massive galaxies over the redshift range 1 < z < 3. Our analysis is based on a bulge-disc decomposition of 396 galaxies with M* > 1011 M⊙ uncovered from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) Wide Field Camera 3 (WFC3)/IR imaging within the Cosmological Evolution Survey (COSMOS) and UKIRT Infrared Deep Sky Survey (UKIDSS) UDS survey fields. We find that, by modelling the H160 image of each galaxy with a combination of a de Vaucouleurs bulge (Sérsic index n = 4) and an exponential disc (n = 1), we can then lock all derived morphological parameters for the bulge and disc components, and successfully reproduce the shorter-wavelength J125, i814, v606 HST images simply by floating the magnitudes of the two components. This then yields sub-divided four-band HST photometry for the bulge and disc components which, with no additional priors, is well described by spectrophotometric models of galaxy evolution. Armed with this information, we are able to properly determine the masses and star formation rates for the bulge and disc components, and find that: (i) from z = 3 to 1 the galaxies move from disc dominated to increasingly bulge dominated, but very few galaxies are pure bulges/ellipticals by z = 1; (ii) while most passive galaxies are bulge dominated, and most star-forming galaxies disc dominated, 18 ± 5 per cent of passive galaxies are disc dominated, and 11 ± 3 per cent of star-forming galaxies are bulge dominated, a result which needs to be explained by any model purporting to connect star formation quenching with morphological transformations; (iii) there exists a small but significant population of pure passive discs, which are generally flatter than their star-forming counterparts (whose axial ratio distribution peaks at b/a ≃ 0.7); (iv) flatter/larger discs re-emerge at the highest star formation rates, consistent with

  18. The Natural Polyphenol Epigallocatechin Gallate Protects Intervertebral Disc Cells from Oxidative Stress

    PubMed Central

    Krupkova, Olga; Handa, Junichi; Hlavna, Marian; Klasen, Juergen; Ospelt, Caroline; Ferguson, Stephen John; Wuertz-Kozak, Karin

    2016-01-01

    Oxidative stress-related phenotypic changes and a decline in the number of viable cells are crucial contributors to intervertebral disc degeneration. The polyphenol epigallocatechin 3-gallate (EGCG) can interfere with painful disc degeneration by reducing inflammation, catabolism, and pain. In this study, we hypothesized that EGCG furthermore protects against senescence and/or cell death, induced by oxidative stress. Sublethal and lethal oxidative stress were induced in primary human intervertebral disc cells with H2O2 (total n = 36). Under sublethal conditions, the effects of EGCG on p53-p21 activation, proliferative capacity, and accumulation of senescence-associated β-galactosidase were tested. Further, the effects of EGCG on mitochondria depolarization and cell viability were analyzed in lethal oxidative stress. The inhibitor LY249002 was applied to investigate the PI3K/Akt pathway. EGCG inhibited accumulation of senescence-associated β-galactosidase but did not affect the loss of proliferative capacity, suggesting that EGCG did not fully neutralize exogenous radicals. Furthermore, EGCG increased the survival of IVD cells in lethal oxidative stress via activation of prosurvival PI3K/Akt and protection of mitochondria. We demonstrated that EGCG not only inhibits inflammation but also can enhance the survival of disc cells in oxidative stress, which makes it a suitable candidate for the development of novel therapies targeting disc degeneration. PMID:27119009

  19. Null generation using discs on a reflector

    NASA Astrophysics Data System (ADS)

    Rudisill, M. D.

    1984-12-01

    It has been shown possible experimentally to produce nulls in the pattern of a prime focus reflector antenna using discs mounted on the dish. A model of this antenna system is developed to evaluate optimal configurations and ideal performance. Aperture integration is the method of analysis used. Discs' effects are modeled as a phase shift on the aperture. No secondary effects, such as diffraction, are considered. Based on the model developed, guidelines are presented for antenna design. A computer code was written to implement the model and a prediction of antenna the system's performance is presented.

  20. Disc valve for sampling erosive process streams

    DOEpatents

    Mrochek, J.E.; Dinsmore, S.R.; Chandler, E.W.

    1986-01-07

    A four-port disc valve is described for sampling erosive, high temperature process streams. A rotatable disc defining opposed first and second sampling cavities rotates between fired faceplates defining flow passageways positioned to be alternatively in axial alignment with the first and second cavities. Silicon carbide inserts and liners composed of [alpha] silicon carbide are provided in the faceplates and in the sampling cavities to limit erosion while providing lubricity for a smooth and precise operation when used under harsh process conditions. 1 fig.

  1. Progression of a lumbar disc extrusion.

    PubMed

    Crowell, Michael S; Alitz, Curtis

    2014-11-01

    The patient was a 34-year-old woman who was referred to a physical therapist for a chief complaint of progressively worsening right buttock pain with paresthesias of the right posterior thigh and calf. Prior magnetic resonance imaging of the patient's lumbar spine revealed a large left paracentral disc extrusion at L5-S1. Following physical therapist intervention, the patient reported a new onset of left posterior thigh pain, with paresthesias of the dorsolateral aspect of the left foot. Repeat magnetic resonance imaging of the patient's lumbar spine revealed an increase in the size of the disc extrusion at L5-S1. PMID:25361862

  2. The effectiveness of percutaneous laser disc decompression for the prolapsed lumbar intervertebral disc

    NASA Astrophysics Data System (ADS)

    Mu, Ming Wei; Liu, Wei; Feng, Wei; Ma, Nan

    2009-07-01

    Objective: to investigate the role of associated factors in the effectiveness of laser treatment for prolapsed lumber intervertebral disc. Method: 302 prolapsed lumber intervertebral discs in 212 patients were treated with percutaneous laser disc decompression (PLDD). Patients were followed up by 12month, the associated factors which affecting the effectiveness of treatment, ie age, duration of illness were analyzed. Results: Punctual Success rate was 100%. After 12 month's follow up, 86% successful outcomes were obtained, in which 93% successful outcomes were obtained in patients less than 50 years old, 92% successful outcomes was obtained in the patients whose duration of illness less than 1 year.

  3. Artificial ecosystem selection.

    PubMed

    Swenson, W; Wilson, D S; Elias, R

    2000-08-01

    Artificial selection has been practiced for centuries to shape the properties of individual organisms, providing Darwin with a powerful argument for his theory of natural selection. We show that the properties of whole ecosystems can also be shaped by artificial selection procedures. Ecosystems initiated in the laboratory vary phenotypically and a proportion of the variation is heritable, despite the fact that the ecosystems initially are composed of thousands of species and millions of individuals. Artificial ecosystem selection can be used for practical purposes, illustrates an important role for complex interactions in evolution, and challenges a widespread belief that selection is most effective at lower levels of the biological hierarchy. PMID:10890915

  4. Excess BMP Signaling in Heterotopic Cartilage Forming in Prg4-null TMJ Discs.

    PubMed

    Bechtold, T E; Saunders, C; Mundy, C; Um, H; Decker, R S; Salhab, I; Kurio, N; Billings, P C; Pacifici, M; Nah, H D; Koyama, E

    2016-03-01

    Heterotopic cartilage develops in certain pathologic conditions, including those affecting the human temporomandibular joint (TMJ), but the underlying molecular mechanisms remain obscure. This is in part due to the fact that a reliable animal model of such TMJ diseases is not available. Here, we show that aberrant chondrocyte differentiation and ectopic cartilage formation occur spontaneously in proteoglycan 4 (Prg4) mutant TMJ discs without further invasive procedure. By 2 mo of age, mutant disc cells displayed chondrocyte transdifferentiation, accompanied by strong expression of cartilage master gene Sox9 and matrix genes aggrecan and type II collagen. By 6 mo, heterotopic cartilage had formed in the discs and expressed cartilage hypertrophic markers Runx2 and ColX. The ectopic tissue grew in size over time and exhibited regional mineralization by 12 mo. Bone morphogenetic protein (BMP) signaling was activated with the ectopic chondrogenic cells and chondrocytes, as indicated by phosphorylated Smad 1/5/8 nuclear staining and by elevated expression of Bmp2, Bmpr1b, Bmpr2, and BMP signaling target genes. Likewise, we found that upon treatment with recombinant human BMP 2 in high-density micromass culture, mutant disc cells differentiated into chondrocytes and synthesized cartilage matrix more robustly than control cells. Importantly, a specific kinase inhibitor of BMP receptors drastically attenuated chondrogenesis in recombinant human BMP 2-treated mutant disc cultures. Unexpectedly, we found that Prg4 was expressed at joint-associated sites, including disc/muscle insertion and muscle/bone interface, and all these structures were abnormal in Prg4 mutants. Our data indicate that Prg4 is needed for TMJ disc integrity and function and that its absence leads to ectopic chondrogenesis and cartilage formation in conjunction with abnormal BMP signaling. Our findings imply that the BMP signaling pathway could be a potential therapeutic target for prevention or inhibition

  5. Thanatology in protoplanetary discs. The combined influence of Ohmic, Hall, and ambipolar diffusion on dead zones

    NASA Astrophysics Data System (ADS)

    Lesur, Geoffroy; Kunz, Matthew W.; Fromang, Sébastien

    2014-06-01

    Protoplanetary discs are poorly ionised due to their low temperatures and high column densities and are therefore subject to three "non-ideal" magnetohydrodynamic (MHD) effects: Ohmic dissipation, ambipolar diffusion, and the Hall effect. The existence of magnetically driven turbulence in these discs has been a central question since the discovery of the magnetorotational instability (MRI). Early models considered Ohmic diffusion only and led to a scenario of layered accretion, in which a magnetically "dead" zone in the disc midplane is embedded within magnetically "active" surface layers at distances of about 1-10 au from the central protostellar object. Recent work has suggested that a combination of Ohmic dissipation and ambipolar diffusion can render both the midplane and surface layers of the disc inactive and that torques due to magnetically driven outflows are required to explain the observed accretion rates. We reassess this picture by performing three-dimensional numerical simulations that include all three non-ideal MHD effects for the first time. We find that the Hall effect can generically "revive" dead zones by producing a dominant azimuthal magnetic field and a large-scale Maxwell stress throughout the midplane, provided that the angular velocity and magnetic field satisfy Ω·B > 0. The attendant large magnetic pressure modifies the vertical density profile and substantially increases the disc scale height beyond its hydrostatic value. Outflows are produced but are not necessary to explain accretion rates ≲ 10-7 M⊙ yr-1. The flow in the disc midplane is essentially laminar, suggesting that dust sedimentation may be efficient. These results demonstrate that if the MRI is relevant for driving mass accretion in protoplanetary discs, one must include the Hall effect to obtain even qualitatively correct results. Appendices are available in electronic form at http://www.aanda.org

  6. Revealing the accretion disc corona in Mrk 335 with multi-epoch X-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Keek, L.; Ballantyne, D. R.

    2016-03-01

    Active galactic nuclei host an accretion disc with an X-ray producing corona around a supermassive black hole. In bright sources, such as the Seyfert 1 galaxy Mrk 335, reflection of the coronal emission off the accretion disc has been observed. Reflection produces spectral features such as an Fe Kα emission line, which allow for properties of the inner accretion disc and the corona to be constrained. We perform a multi-epoch spectral analysis of all XMM-Newton, Suzaku, and NuSTAR observations of Mrk 335, and we optimize our fitting procedure to unveil correlations between the Eddington ratio and the spectral parameters. We find that the disc's ionization parameter correlates strongly with the Eddington ratio: the inner disc is more strongly ionized at higher flux. The slope of the correlation is less steep than previously predicted. Furthermore, the cut-off of the power-law spectrum increases in energy with the Eddington ratio, whereas the reflection fraction exhibits a decrease. We interpret this behaviour as geometrical changes of the corona as a function of the accretion rate. Below ˜10 per cent of the Eddington limit, the compact and optically thick corona is located close to the inner disc, whereas at higher accretion rates the corona is likely optically thin and extends vertically further away from the disc surface. Furthermore, we find a soft excess that consists of two components. In addition to a contribution from reflection in low ionization states, a second component is present that traces the overall flux.

  7. The role of interleukin-1 in the pathogenesis of human Intervertebral disc degeneration

    PubMed Central

    Le Maitre, Christine Lyn; Freemont, Anthony J; Hoyland, Judith Alison

    2005-01-01

    In this study, we investigated the hypotheses that in human intervertebral disc (IVD) degeneration there is local production of the cytokine IL-1, and that this locally produced cytokine can induce the cellular and matrix changes of IVD degeneration. Immunohistochemistry was used to localize five members of the IL-1 family (IL-1α, IL-1β, IL-1Ra (IL-1 receptor antagonist), IL-1RI (IL-1 receptor, type I), and ICE (IL-1β-converting enzyme)) in non-degenerate and degenerate human IVDs. In addition, cells derived from non-degenerate and degenerate human IVDs were challenged with IL-1 agonists and the response was investigated using real-time PCR for a number of matrix-degrading enzymes, matrix proteins, and members of the IL-1 family. This study has shown that native disc cells from non-degenerate and degenerate discs produced the IL-1 agonists, antagonist, the active receptor, and IL-1β-converting enzyme. In addition, immunopositivity for these proteins, with the exception of IL-1Ra, increased with severity of degeneration. We have also shown that IL-1 treatment of human IVD cells resulted in increased gene expression for the matrix-degrading enzymes (MMP 3 (matrix metalloproteinase 3), MMP 13 (matrix metalloproteinase 13), and ADAMTS-4 (a disintegrin and metalloproteinase with thrombospondin motifs)) and a decrease in the gene expression for matrix genes (aggrecan, collagen II, collagen I, and SOX6). In conclusion we have shown that IL-1 is produced in the degenerate IVD. It is synthesized by native disc cells, and treatment of human disc cells with IL-1 induces an imbalance between catabolic and anabolic events, responses that represent the changes seen during disc degeneration. Therefore, inhibiting IL-1 could be an important therapeutic target for preventing and reversing disc degeneration. PMID:15987475

  8. Adipose-Derived Stromal Cells Protect Intervertebral Disc Cells in Compression: Implications for Stem Cell Regenerative Disc Therapy

    PubMed Central

    Sun, Zhen; Luo, Beier; Liu, Zhi-Heng; Samartzis, Dino; Liu, Zhongyang; Gao, Bo; Huang, Liangliang; Luo, Zhuo-Jing

    2015-01-01

    Introduction: Abnormal biomechanics plays a role in intervertebral disc degeneration. Adipose-derived stromal cells (ADSCs) have been implicated in disc integrity; however, their role in the setting of mechanical stimuli upon the disc's nucleus pulposus (NP) remains unknown. As such, the present study aimed to evaluate the influence of ADSCs upon NP cells in compressive load culture. Methods: Human NP cells were cultured in compressive load at 3.0MPa for 48 hours with or without ADSCs co-culture (the ratio was 50:50). We used flow cytometry, live/dead staining and scanning electron microscopy (SEM) to evaluate cell death, and determined the expression of specific apoptotic pathways by characterizing the expression of activated caspases-3, -8 and -9. We further used real-time (RT-) PCR and immunostaining to determine the expression of the extracellular matrix (ECM), mediators of matrix degradation (e.g. MMPs, TIMPs and ADAMTSs), pro-inflammatory factors and NP cell phenotype markers. Results: ADSCs inhibited human NP cell apoptosis via suppression of activated caspase-9 and caspase-3. Furthermore, ADSCs protected NP cells from the degradative effects of compressive load by significantly up-regulating the expression of ECM genes (SOX9, COL2A1 and ACAN), tissue inhibitors of metalloproteinases (TIMPs) genes (TIMP-1 and TIMP-2) and cytokeratin 8 (CK8) protein expression. Alternatively, ADSCs showed protective effect by inhibiting compressive load mediated increase of matrix metalloproteinases (MMPs; MMP-3 and MMP-13), disintegrin and metalloproteinase with thrombospondin motifs (ADAMTSs; ADAMTS-1 and 5), and pro-inflammatory factors (IL-1beta, IL-6, TGF-beta1 and TNF-alpha). Conclusions: Our study is the first in vitro study assessing the impact of ADSCs on NP cells in an un-physiological mechanical stimulation culture environment. Our study noted that ADSCs protect compressive load induced NP cell death and degradation by inhibition of activated caspase-9 and -3

  9. Artificial Sweeteners: A systematic review of metabolic effects in youth

    PubMed Central

    Brown, Rebecca J.; De Banate, Mary Ann; Rother, Kristina I.

    2010-01-01

    Epidemiological data have demonstrated an association between artificial sweetener use and weight gain. Evidence of a causal relationship linking artificial sweetener use to weight gain and other metabolic health effects is limited. However, recent animal studies provide intriguing information that supports an active metabolic role of artificial sweeteners. This systematic review examines the current literature on artificial sweetener consumption in children and its health effects. Eighteen studies were identified. Data from large, epidemiologic studies support the existence of an association between artificially-sweetened beverage consumption and weight gain in children. Randomized controlled trials in children are very limited, and do not clearly demonstrate either beneficial or adverse metabolic effects of artificial sweeteners. Presently, there is no strong clinical evidence for causality regarding artificial sweetener use and metabolic health effects, but it is important to examine possible contributions of these common food additives to the global rise in pediatric obesity and diabetes. PMID:20078374

  10. The artificial leaf.

    PubMed

    Nocera, Daniel G

    2012-05-15

    To convert the energy of sunlight into chemical energy, the leaf splits water via the photosynthetic process to produce molecular oxygen and hydrogen, which is in a form of separated protons and electrons. The primary steps of natural photosynthesis involve the absorption of sunlight and its conversion into spatially separated electron-hole pairs. The holes of this wireless current are captured by the oxygen evolving complex (OEC) of photosystem II (PSII) to oxidize water to oxygen. The electrons and protons produced as a byproduct of the OEC reaction are captured by ferrodoxin of photosystem I. With the aid of ferrodoxin-NADP(+) reductase, they are used to produce hydrogen in the form of NADPH. For a synthetic material to realize the solar energy conversion function of the leaf, the light-absorbing material must capture a solar photon to generate a wireless current that is harnessed by catalysts, which drive the four electron/hole fuel-forming water-splitting reaction under benign conditions and under 1 sun (100 mW/cm(2)) illumination. This Account describes the construction of an artificial leaf comprising earth-abundant elements by interfacing a triple junction, amorphous silicon photovoltaic with hydrogen- and oxygen-evolving catalysts made from a ternary alloy (NiMoZn) and a cobalt-phosphate cluster (Co-OEC), respectively. The latter captures the structural and functional attributes of the PSII-OEC. Similar to the PSII-OEC, the Co-OEC self-assembles upon oxidation of an earth-abundant metal ion from 2+ to 3+, may operate in natural water at room temperature, and is self-healing. The Co-OEC also activates H(2)O by a proton-coupled electron transfer mechanism in which the Co-OEC is increased by four hole equivalents akin to the S-state pumping of the Kok cycle of PSII. X-ray absorption spectroscopy studies have established that the Co-OEC is a structural relative of Mn(3)CaO(4)-Mn cubane of the PSII-OEC, where Co replaces Mn and the cubane is extended in a

  11. Convergence of smoothed particle hydrodynamics simulations of self-gravitating accretion discs: sensitivity to the implementation of radiative cooling

    NASA Astrophysics Data System (ADS)

    Rice, W. K. M.; Forgan, D. H.; Armitage, P. J.

    2012-02-01

    Recent simulations of self-gravitating accretion discs, carried out using a three-dimensional smoothed particle hydrodynamics (SPH) code by Meru & Bate, have been interpreted as implying that three-dimensional global discs fragment much more easily than would be expected from a two-dimensional local model. Subsequently, global and local two-dimensional models have been shown to display similar fragmentation properties, leaving it unclear whether the three-dimensional results reflect a physical effect or a numerical problem associated with the treatment of cooling or artificial viscosity in SPH. Here, we study how fragmentation of self-gravitating disc flows in SPH depends upon the implementation of cooling. We run disc simulations that compare a simple cooling scheme, in which each particle loses energy based upon its internal energy per unit mass, with a method in which the cooling is derived from a smoothed internal energy density field. For the simple per particle cooling scheme, we find a significant increase in the minimum cooling time-scale for fragmentation with increasing resolution, matching previous results. Switching to smoothed cooling, however, results in lower critical cooling time-scales, and tentative evidence for convergence at the highest spatial resolution tested. We conclude that precision studies of fragmentation using SPH require careful consideration of how cooling (and, probably, artificial viscosity) is implemented, and that the apparent non-convergence of the fragmentation boundary seen in prior simulations is likely a numerical effect. In real discs, where cooling is physically smoothed by radiative transfer effects, the fragmentation boundary is probably displaced from the two-dimensional value by a factor that is only of the order of unity.

  12. Introduction to artificial intelligence

    SciTech Connect

    Gevarter, W.B.

    1987-09-01

    The author discusses the development of artificial intelligence (AI). He explains the basic elements of AI: Heuristic search, knowledge representation, AI languages and tools, Natural Language Processing, computer vision, expert systems and problem solving and planning.

  13. Intelligence: Real or artificial?

    PubMed Central

    Schlinger, Henry D.

    1992-01-01

    Throughout the history of the artificial intelligence movement, researchers have strived to create computers that could simulate general human intelligence. This paper argues that workers in artificial intelligence have failed to achieve this goal because they adopted the wrong model of human behavior and intelligence, namely a cognitive essentialist model with origins in the traditional philosophies of natural intelligence. An analysis of the word “intelligence” suggests that it originally referred to behavior-environment relations and not to inferred internal structures and processes. It is concluded that if workers in artificial intelligence are to succeed in their general goal, then they must design machines that are adaptive, that is, that can learn. Thus, artificial intelligence researchers must discard their essentialist model of natural intelligence and adopt a selectionist model instead. Such a strategic change should lead them to the science of behavior analysis. PMID:22477051

  14. Artificial Sweeteners and Cancer

    MedlinePlus