Science.gov

Sample records for polished tapered stem

  1. Stem subsidence of polished and rough double-taper stems

    PubMed Central

    Yamada, Kengo; Hirosaki, Kenichi; Takano, Masahiro; Matsumoto, Tadami

    2009-01-01

    Background and purpose Many clinical reports have indicated that polished hip stems show better clinical results than rough stems of the same geometry. It is still unknown, however, what the mechanical effects are of different surface finishes on the cement at the cement-bone interface. We compared mechanical effects in an in vitro cemented hip arthroplasty model. Methods Two sizes of double-taper polished stems and matt-processed polished stems (rough stems) were fixed into composite femurs. A 1-Hz dynamic load was applied to the stems for 1 million cycles. An 8-h no-load period was set after every 16 h of load. Stem subsidence within the cement, and compressive force and horizontal cement creep at the cement-bone interface, were measured. Results Compared to rough stems, stem subsidence, compressive force and cement creep for polished stems were a maximum of 4, 12, and 7-fold greater, respectively. There was a strong positive correlation between stem subsidence and compressive force for polished stems. In contrast, a strong negative correlation was found between stem subsidence and compressive force for rough stems. There was also a statistically significant relationship between compressive force on the cement and cement creep for the polished stems, but no significant relationship was found for rough stems. Interpretation This is the first evidence that different surface finishes of stems can have different mechanical effects on the cement at the cement-bone interface. Stem subsidence in polished stems resulted in compressive force on the cement and cement creep. The mechanical effects that polished taper stems impart on cement at the cement-bone interface probably contribute to their good long-term fixation and excellent clinical outcome. PMID:19421909

  2. The influence of cement thickness on stem subsidence and cement creep in a collarless polished tapered stem

    PubMed Central

    Takahashi, E.; Tsuda, R.; Numata, Y.; Ichiseki, T.; Fukui, K.; Kawahara, N.

    2017-01-01

    Objectives Favourable results for collarless polished tapered stems have been reported, and cement creep due to taper slip may be a contributing factor. However, the ideal cement thickness around polished stems remains unknown. We investigated the influence of cement thickness on stem subsidence and cement creep. Methods We cemented six collarless polished tapered (CPT) stems (two stems each of small, medium and large sizes) into composite femurs that had been reamed with a large CPT rasp to achieve various thicknesses of the cement mantle. Two or three tantalum balls were implanted in the proximal cement in each femur. A cyclic loading test was then performed for each stem. The migration of the balls was measured three-dimensionally, using a micro-computed tomography (CT) scanner, before and after loading. A digital displacement gauge was positioned at the stem shoulder, and stem subsidence was measured continuously by the gauge. Final stem subsidence was measured at the balls at the end of each stem. Results A strong positive correlation was observed between mean cement thickness and stem subsidence in the CT slices on the balls. In the small stems, the balls moved downward to almost the same extent as the stem. There was a significant negative correlation between cement thickness and the horizontal:downward ratio of ball movement. Conclusion Collarless polished tapered stems with thicker cement mantles resulted in greater subsidence of both stem and cement. This suggests that excessive thickness of the cement mantle may interfere with effective radial cement creep. Cite this article: E. Takahashi, A. Kaneuji, R. Tsuda, Y. Numata, T. Ichiseki, K. Fukui, N. Kawahara. The influence of cement thickness on stem subsidence and cement creep in a collarless polished tapered stem: When are thick cement mantles detrimental? Bone Joint Res 2017;6:–357. DOI: 10.1302/2046-3758.65.BJR-2017-0028.R1. PMID:28566327

  3. Radiographic evaluation of cementation technique using polished, conical, triple-tapered femoral stem in hip arthroplasty.

    PubMed

    Schuroff, Ademir Antônio; Deeke, Mark; Pedroni, Marco Antônio; Lupselo, Fernando Silva; Kunz, Rodrigo Ernesto; Lima, Alexandre Matos

    2017-01-01

    To radiographically evaluate the quality of cementation and implantation technique using a polished, triple-tapered femoral stem in total hip arthroplasty (THA). Retrospective study with radiographic evaluation of 86 hips in 83 patients who underwent to primary THA with the triple-tapered cemented femoral stem C-Stem (DePuy Orthopedics, Warsaw, Indiana). Cases with at least one-year of follow-up were included, and data related to preoperative, immediate postoperative, and late postoperative radiographic evolution were recorded. This study analyzed, among others, the proximal femoral anatomy, the quality of cementation as described by Barrack, and the implant positioning. Cementation was also evaluated and quantified in the Gruen zones with one-year of follow-up. The mean age was 62.85 years. Proximal femoral anatomical conformation was Dorr type A in 34 (39.53%) cases, type B in 52 (60.46%), and no type C cases were found. Five (5.81%) cases were defined as type A by Barrack's cementation classification system, 46 (56.49%) type B, 27 (31.40%) type C, and eight (9.30%) type D. The greatest cement mantle thickness was observed in zones four (15.53 mm) and 11 (15.64 mm), and the smallest in zone nine (3.51 mm). Positioning in varus was observed in eight (9.3%) cases, valgus in 25 (29%), forward deviation in two (5%), and backward deviation in 55 (63.95%). The C-Stem femoral system presented satisfactory results related to cementation pattern, positioning, osteolysis, and stress shielding with regard to literature referring to double-tapered or triple-tapered models, demonstrating to be a safe method, with a predictable and reliable cementing pattern.

  4. The influence of cement thickness on stem subsidence and cement creep in a collarless polished tapered stem: When are thick cement mantles detrimental?

    PubMed

    Takahashi, E; Kaneuji, A; Tsuda, R; Numata, Y; Ichiseki, T; Fukui, K; Kawahara, N

    2017-05-01

    Favourable results for collarless polished tapered stems have been reported, and cement creep due to taper slip may be a contributing factor. However, the ideal cement thickness around polished stems remains unknown. We investigated the influence of cement thickness on stem subsidence and cement creep. We cemented six collarless polished tapered (CPT) stems (two stems each of small, medium and large sizes) into composite femurs that had been reamed with a large CPT rasp to achieve various thicknesses of the cement mantle. Two or three tantalum balls were implanted in the proximal cement in each femur. A cyclic loading test was then performed for each stem. The migration of the balls was measured three-dimensionally, using a micro-computed tomography (CT) scanner, before and after loading. A digital displacement gauge was positioned at the stem shoulder, and stem subsidence was measured continuously by the gauge. Final stem subsidence was measured at the balls at the end of each stem. A strong positive correlation was observed between mean cement thickness and stem subsidence in the CT slices on the balls. In the small stems, the balls moved downward to almost the same extent as the stem. There was a significant negative correlation between cement thickness and the horizontal:downward ratio of ball movement. Collarless polished tapered stems with thicker cement mantles resulted in greater subsidence of both stem and cement. This suggests that excessive thickness of the cement mantle may interfere with effective radial cement creep.Cite this article: E. Takahashi, A. Kaneuji, R. Tsuda, Y. Numata, T. Ichiseki, K. Fukui, N. Kawahara. The influence of cement thickness on stem subsidence and cement creep in a collarless polished tapered stem: When are thick cement mantles detrimental? Bone Joint Res 2017;6:-357. DOI: 10.1302/2046-3758.65.BJR-2017-0028.R1. © 2017 Kaneuji et al.

  5. High risk of early periprosthetic fractures after primary hip arthroplasty in elderly patients using a cemented, tapered, polished stem

    PubMed Central

    Brodén, Cyrus; Mukka, Sebastian; Muren, Olle; Eisler, Thomas; Boden, Henrik; Stark, André; Sköldenberg, Olof

    2015-01-01

    Background and purpose Postoperative periprosthetic femoral fracture (PPF) after hip arthroplasty is associated with considerable morbidity and mortality. We assessed the incidence and characteristics of periprosthetic fractures in a consecutive cohort of elderly patients treated with a cemented, collarless, polished and tapered femoral stem (CPT). Patients and methods In this single-center prospective cohort study, we included 1,403 hips in 1,357 patients (mean age 82 (range 52–102) years, 72% women) with primary osteoarthritis (OA) or a femoral neck fracture (FNF) as indication for surgery (367 hips and 1,036 hips, respectively). 64% of patients were ASA class 3 or 4. Hip-related complications and need for repeat surgery were assessed at a mean follow-up time of 4 (1–7) years. A Cox regression analysis was used to evaluate risk factors associated with PPF. Results 47 hips (3.3%) sustained a periprosthetic fracture at median 7 (2–79) months postoperatively; 41 were comminute Vancouver B2 or complex C-type fractures. The fracture rate was 3.8% for FNF patients and 2.2% for OA patients (hazard ratio (HR) = 4; 95% CI: 1.3–12). Patients > 80 years of age also had a higher risk of fracture (HR = 2; 95% CI: 1.1–4.5). Interpretation We found a high incidence of early PPF associated with the CPT stem in this old and frail patient group. A possible explanation may be that the polished tapered stem acts as a wedge, splitting the femur after a direct hip contusion. Our results should be confirmed in larger, registry-based studies, but we advise caution when using this stem for this particular patient group. PMID:25280133

  6. Initial Evaluation on Subsidence of Cemented Collarless Polished Tapered Stem Applied to the Patients with Narrow Femoral Medullar Canal

    PubMed Central

    Dairaku, Katsuyuki; Ishii, Masaji; Kobayashi, Shinji; Kawaji, Hiroyuki; Sasaki, Kan; Takakubo, Yuya; Takagi, Michiaki

    2010-01-01

    Purpose: The geometry of the proximal femur is one of the important factors for choosing the suitable stem. We have been applied cemented collarless polished tapered (CPT) stem to the patients with small femur. Radiographic evaluation was performed to access the clinical feature of the stem in early stage of the follow-up. Methods: One hundred total hip arthroplasties with CPT system were performed between October 2004 to February 2006. This study focused on the 53 cases to whom size 1 or smaller sized stem were implanted, and its post-operative period was 41 months (30-46 months). Morphologic classification of preoperative proximal femur, stem alignment, thickness of the cement mantle, cementing technique, subsidence of the stem, improvement in the bone-cement interface, and stress shielding were assessed. Results: The size of the inserted stem was X-SMALL in one case, SMALL in two cases, SIZE 0 in 12 cases, and SIZE 1 in 38 cases. Canal shape of proximal femur was stovepipe type in five cases, normal type in 43 cases, and champagne-flute type in five cases. There was no subsidence in eight cases. 44 stems subsided within 1 mm, one stem subsided 1 to 2 mm, and no stem subsided over 2 mm. In 39 of 45 cases, subsidence was appeared within six months after operation. Marked progressive and excessive subsidence was not seen after the two years of follow-up. Conclusions: Short term radiographic results of THA with CPT stem to small femur were satisfactory with less unfavorable radiographic findings, which imply contribution to longer survivorship of the stem. PMID:20448819

  7. Substantially higher prevalence of postoperative peri­prosthetic fractures in octogenarians with hip fractures operated with a cemented, polished tapered stem rather than an anatomic stem

    PubMed Central

    Mukka, Sebastian; Mellner, Carl; Knutsson, Björn; Sayed-Noor, Arkan; Sköldenberg, Olof

    2016-01-01

    Background and purpose Recent studies have demonstrated a high incidence of postoperative periprosthetic femoral fracture (PPF) in elderly patients treated with 2 commonly used cemented, polished tapered stems. We compared the prevalence and incidence rate of PPF in a consecutive cohort of octagenerians with femoral neck fractures (FNFs) treated with either a collarless, polished tapered (CPT) stem or an anatomic matte stem (Lubinus SP2). Patients and methods In a multicenter, prospective cohort study, we included 979 hips in patients aged 80 years and above (72% females, median age 86 (80–102) years) with a femoral neck fracture as indication for surgery. 69% of the patients were classified as ASA class 3 or 4. Hip-related complications and repeat surgery were assessed at a median follow-up of 20 (0–24) months postoperatively. Results 22 hips (2.2%) sustained a PPF at a median of 7 (0–22) months postoperatively; 14 (64%) were Vancouver B2 fractures. 7 of the 22 surgically treated fractures required revision surgery, mainly due to deep infection. The cumulative incidence of PPFs was 3.8% in the CPT group, as compared with 0.2% in the SP2 group (p < 0.001). The risk ratio (RR) was 16 (95% CI: 2–120) using the SP2 group as denominator. Interpretation The CPT stem was associated with a higher risk of PPF than the SP2 stem. We suggest that the tapered CPT stem should not be used for the treatment of femoral neck fractures in patients over 80 years. PMID:27045318

  8. Femoral impaction bone allografting with an Exeter cemented collarless, polished, tapered stem in revision hip replacement: a mean follow-up of 10.5 years.

    PubMed

    Wraighte, P J; Howard, P W

    2008-08-01

    Femoral impaction bone allografting has been developed as a means of restoring bone stock in revision total hip replacement. We report the results of 75 consecutive patients (75 hips) with a mean age of 68 years (35 to 87) who underwent impaction grafting using the Exeter collarless, polished, tapered femoral stem between 1992 and 1998. The mean follow-up period was 10.5 years (6.3 to 14.1). The median pre-operative bone defect score was 3 (interquartile range (IQR) 2 to 3) using the Endo-Klinik classification. The median subsidence at one year post-operatively was 2 mm (IQR 1 to 3). At the final review the median Harris hip score was 80.6 (IQR 67.6 to 88.9) and the median subsidence 2 mm (IQR 1 to 4). Incorporation of the allograft into trabecular bone and secondary remodelling were noted radiologically at the final follow-up in 87% (393 of 452 zones) and 40% (181 of 452 zones), respectively. Subsidence of the Exeter stem correlated with the pre-operative Endo-Klinik bone loss score (p = 0.037). The degree of subsidence at one year had a strong association with long-term subsidence (p < 0.001). There was a significant correlation between previous revision surgery and a poor Harris Hip score (p = 0.028), and those who had undergone previous revision surgery for infection had a higher risk of complications (p = 0.048). Survivorship at 10.5 years with any further femoral operation as the end-point was 92% (95% confidence interval 82 to 97).

  9. A Cannulated Tri-Tapered Femoral Stem for Total Hip Arthroplasty: Clinical and Radiological Results at Ten Years.

    PubMed

    Rajakulendran, Karthig; Strambi, Francesco; Ruggeri, Riccardo; Field, Richard E

    2015-10-01

    We report the ten-year clinical and radiological outcomes of a novel cannulated, tri-tapered femoral stem, used in primary total hip arthroplasty (110 stems in 98 patients). At ten years, two Tri-taper stems had been revised for infection and dislocation. The mean Oxford Hip Score improved from 13.46 pre-operatively, to 37.04. Radiological analysis revealed radiolucent lines in 57 cases, but none exceeded 2 mm thickness. Stem subsidence was identified in 63 cases, with mean distal tip migration of 3.8 mm. Survivorship with revision for aseptic loosening as the end point was 100% at 10 years. Stem survival with revision for any cause was 98.2% (95% CI, 92.9% to 99.5%). The ten-year results of the Tri-taper stem are comparable to other polished, tapered femoral stems. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. The influence of proximal stem geometry and surface finish on the fixation of a double-tapered cemented femoral stem.

    PubMed

    Sangiorgio, Sophia N; Longjohn, Donald B; Dorr, Lawrence D; Ebramzadeh, Edward

    2011-01-04

    In this study, the in vitro fixation of four otherwise identical double-tapered stem-types, varying only in surface finish (polished or matte) and proximal stem geometry (with or without flanges) were compared under two conditions. First, four specimens of each stem type were tested with initially bonded stem-cement interfaces, representing early post-operative conditions. Then, simulating conditions a few weeks to months later, stems were implanted in unused synthetic femurs, with a thin layer coating the stem to prevent stem-cement adhesion. Per-cycle motions were measured at both cement interfaces throughout loading. Overall, surface finish had the smallest relative effect on fixation compared to flanges. Flanges increased axial fixation by 22 μm per-cycle, regardless of surface finish (P=0.01). Further, all stems moved under dynamic load at the stem-cement interface during the first few cycles of loading, even without a thin film. The results indicate that flanges have a greater effect on fixation than surface finish, and therefore adverse findings about matte surfaces should not necessarily apply to all double-tapered stems. Specifically, dorsal flanges enhance the stability of a tapered cemented femoral stem, regardless of surface finish.

  11. The Effect of Taper Angle and Spline Geometry on the Initial Stability of Tapered, Splined Modular Titanium Stems.

    PubMed

    Pierson, Jeffery L; Small, Scott R; Rodriguez, Jose A; Kang, Michael N; Glassman, Andrew H

    2015-07-01

    Design parameters affecting initial mechanical stability of tapered, splined modular titanium stems (TSMTSs) are not well understood. Furthermore, there is considerable variability in contemporary designs. We asked if spline geometry and stem taper angle could be optimized in TSMTS to improve mechanical stability to resist axial subsidence and increase torsional stability. Initial stability was quantified with stems of varied taper angle and spline geometry implanted in a foam model replicating 2cm diaphyseal engagement. Increased taper angle and a broad spline geometry exhibited significantly greater axial stability (+21%-269%) than other design combinations. Neither taper angle nor spline geometry significantly altered initial torsional stability.

  12. Catastrophic stem taper wear in ceramic on polyethylene bearing couple: a case report.

    PubMed

    Kusaba, Atsushi; Katsui, Mariko; Hakuta, Naoyuki; Tsuchida, Masashi; Maeda, Akihiko; Kondo, Saiji

    2014-01-01

    A severe abrasion occurred at the stem taper 13 years after total hip arthroplasty. The bearing couple was 28 mm ceramic on polyethylene. The ceramic head had almost no damage, whereas the stem taper had severe damage. An ectopic bone probably contributed to the abrasion. The ectopic bone had grown to restrict the normal motion in the bearing couple and all stress and torque seemed to concentrate in the junction until the junction obtained mobility instead of the original bearing couple.

  13. Cementless Tapered Wedge Femoral Stems Decrease Subsidence in Obese Patients Compared to Traditional Fit-and-Fill Stems.

    PubMed

    Grant, Tanner W; Lovro, Luke R; Licini, David J; Warth, Lucian C; Ziemba-Davis, Mary; Meneghini, Robert M

    2017-03-01

    Femoral component stability and resistance to subsidence is critical for osseointegration and clinical success in cementless total hip arthroplasty. The purpose of this study was to radiographically evaluate the anatomic fit and subsidence of 2 different proximally tapered, porous-coated modern cementless femoral component designs. A retrospective cohort study of 126 consecutive cementless total hip arthroplasties was performed. Traditional fit-and-fill stems were implanted in the first 61 hips with the remaining 65 receiving morphometric tapered wedge stems. Preoperative bone morphology was radiographically assessed by the canal flare index. Canal fill in the coronal plane, subsidence, and the sagittal alignment of stems was measured digitally on immediate and 1-month postoperative radiographs. Demographics and canal flare indices were similar between groups. The percentage of femoral canal fill was greater in the tapered wedge compared to the fit-and-fill stem (P = .001). There was significantly less subsidence in the tapered wedge design (0.3 mm) compared to the fit-and-fill design (1.1 mm) (P = .001). Subsidence significantly increased as body mass index (BMI) increased in the fit-and-fill stems, a finding not observed in the tapered wedge design (P = .013). An anatomically designed morphometric tapered wedge femoral stem demonstrated greater axial stability and decreased subsidence with increasing BMI than a traditional fit-and-fill stem. The resistance to subsidence, irrespective of BMI, is likely due to the inherent axial stability of a tapered wedge design and may be the optimal stem design for obese patients. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Taper-based system for estimating stem volumes of upland oaks

    Treesearch

    Donald E. Hilt

    1980-01-01

    A taper-based system for estimating stem volumes is developed for Central States upland oaks. Inside bark diameters up the stem are predicted as a function of dbhib, total height, and powers and relative height. A Fortran IV computer program, OAKVOL, is used to predict cubic and board-foot volumes to any desired merchantable top dib. Volumes of...

  15. Development and verification of a cementless novel tapered wedge stem for total hip arthroplasty.

    PubMed

    Faizan, Ahmad; Wuestemann, Thies; Nevelos, Jim; Bastian, Adam C; Collopy, Dermot

    2015-02-01

    Most current tapered wedge hip stems were designed based upon the original Mueller straight stem design introduced in 1977. These stems were designed to have a single medial curvature and grew laterally to accommodate different sizes. In this preclinical study, the design and verification of a tapered wedge stem using computed tomography scans of 556 patients are presented. The computer simulation demonstrated that the novel stem, designed for proximal engagement, allowed for reduced distal fixation, particularly in the 40-60 year male population. Moreover, the physical micromotion testing and finite element analysis demonstrated that the novel stem allowed for reduced micromotion. In summary, preclinical data suggest that the computed tomography based stem design described here may offer enhanced implant fit and reduced micromotion.

  16. Quantification of the Contact Area at the Head-Stem Taper Interface of Modular Hip Prostheses

    PubMed Central

    Witt, Florian; Gührs, Julian; Morlock, Michael M.; Bishop, Nicholas E.

    2015-01-01

    Corrosion of modular taper junctions of hip implants may be associated with clinical failure. Taper design parameters, as well as the intraoperatively applied assembly forces, have been proposed to affect corrosion. Fretting corrosion is related to relative interface shear motion and fluid ingress, which may vary with contact force and area. It was hypothesised in this study that assembly forces modify the extent and distribution of the surface contact area at the taper interface between a cobalt chrome head and titanium stem taper with a standard threaded surface profile. Local abrasion of a thin gold coating applied to the stem taper prior to assembly was used to determine the contact area after disassembly. Profilometry was then used to assess permanent deformation of the stem taper surface profile. With increasing assembly force (500 N, 2000 N, 4000 N and 8000 N) the number of stem taper surface profile ridges in contact with the head taper was found to increase (9.2±9.3%, 65.4±10.8%, 92.8±6.0% and 100%) and the overall taper area in contact was also found to increase (0.6±0.7%, 5.5±1.0%, 9.9±1.1% and 16.1±0.9%). Contact was inconsistently distributed over the length of the taper. An increase in plastic radial deformation of the surface ridges (-0.05±0.14 μm, 0.1±0.14 μm, 0.21±0.22 μm and 0.96±0.25 μm) was also observed with increasing assembly force. The limited contact of the taper surface ridges at lower assembly forces may influence corrosion rates, suggesting that the magnitude of the assembly force may affect clinical outcome. The method presented provides a simple and practical assessment of the contact area at the taper interface. PMID:26280914

  17. Damage Patterns at the Head-Stem Taper Junction Helps Understand the Mechanisms of Material Loss.

    PubMed

    Hothi, Harry S; Panagiotopoulos, Andreas C; Whittaker, Robert K; Bills, Paul J; McMillan, Rebecca A; Skinner, John A; Hart, Alister J

    2017-01-01

    Material loss at the taper junction of metal-on-metal total hip arthroplasties has been implicated in their early failure. The mechanisms of material loss are not fully understood; analysis of the patterns of damage at the taper can help us better understand why material loss occurs at this junction. We mapped the patterns of material loss in a series of 155 metal-on-metal total hip arthroplasties received at our center by scanning the taper surface using a roundness-measuring machine. We examined these material loss maps to develop a 5-tier classification system based on visual differences between different patterns. We correlated these patterns to surgical, implant, and patient factors known to be important for head-stem taper damage. We found that 63 implants had "minimal damage" at the taper (material loss <1 mm(3)), and the remaining 92 implants could be categorized by 4 distinct patterns of taper material loss. We found that (1) head diameter and (2) time to revision were key significant variables separating the groups. These material loss maps allow us to suggest different mechanisms that dominate the cause of the material loss in each pattern: (1) corrosion, (2) mechanically assisted corrosion, or (3) intraoperative damage or poor size tolerances leading to toggling of trunnion in taper. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. A short tapered stem reduces intraoperative complications in primary total hip arthroplasty.

    PubMed

    Molli, Ryan G; Lombardi, Adolph V; Berend, Keith R; Adams, Joanne B; Sneller, Michael A

    2012-02-01

    While short-stem design is not a new concept, interest has surged with increasing utilization of less invasive techniques. Short stems are easier to insert through small incisions. Reliable long-term results including functional improvement, pain relief, and implant survival have been reported with standard tapered stems, but will a short taper perform as well? We compared short, flat-wedge, tapered, broach-only femoral stems to standard-length, double-tapered, ream and broach femoral stems in terms of intraoperative complications, short-term survivorship, and pain and function scores. We retrospectively reviewed the records of 606 patients who had 658 THAs using a less invasive direct lateral approach from January 2006 to March 2008. Three hundred sixty patients (389 hips) had standard-length stems and 246 (269 hips) had short stems. Age averaged 63 years, and body mass index averaged 30.7 kg/m(2). We recorded complications and pain and function scores and computed short-term survival. Minimum followup was 0.8 months (mean, 29.2 months; range, 0.8-62.2 months). We observed a higher rate of intraoperative complications with the standard-length stems (3.1%; three trochanteric avulsions, nine femoral fractures) compared with the shorter stems (0.4%; one femoral fracture) and managed all complications with application of one or more cerclage cables. There were no differences in implant survival, Harris hip score, and Lower Extremity Activity Scale score between groups. Fewer intraoperative complications occurred with the short stems, attesting to the easier insertion of these devices. While longer followup is required, our early results suggest shortened stems can be used with low complication rates and do not compromise the survival and functional outcome of cementless THA. Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

  19. Feasibility of early tapering of cyclosporine following reduced-intensity stem cell transplantation for advanced hematologic or solid malignancies.

    PubMed

    Hori, Akiko; Kami, Masahiro; Ohnishi, Mutsuko; Murashige, Naoko; Kojima, Rie; Takaue, Yoichi

    2005-07-01

    Although some researchers have reported that early tapering of cyclosporine is feasible and beneficial to augment graft-versus-leukemia effects after conventional stem-cell transplantation, there is little information on the feasibility of this strategy following reduced-intensity stem cell transplantation (RIST). We summarized outcomes of 17 patients who underwent early tapering of cyclosporine following RIST from HLA-identical siblings.

  20. Effects of Prosthesis Stem Tapers on Stress Distribution of Cemented Hip Arthroplasty

    SciTech Connect

    Abdullah, Abdul Halim; Nor, Mohd Asri Mohd; Saman, Alias Mohd; Tamin, Mohd Nasir; Kadir, Mohammed Rafiq Abdul

    2010-10-15

    Aseptic loosening effects are critical issues in encouraging long term stability of cemented hip arthroplasty. Stress shielding is believed to be an important factor that contributes to the aseptic loosening problems. The numerous changes in the prosthesis stem design are intended to minimize the stress shielding and aseptic loosening problems and to improve the long term performance of the implants. In this study, the stress distribution in cemented hip arthroplasty is established using finite element method. The taper of the prosthesis is designed to be 3 deg. at anterior/posterior, 3 deg. at medial/lateral and 10 deg. from wide lateral to narrow medial. Major muscle loads and contact forces are simulated for walking (toe-off phase) and stair climbing load cases. Effects of prosthesis stem tapers on the resulting stress distribution are investigated. Results show that compressive stress dominates in the medial plane while tensile stress in the lateral plane of the femur. The corresponding stress levels of intact femur for walking and stair-climbing load cases are 22 and 29 MPa, respectively. The magnitude of Tresca stress for the THA femur in stair-climbing load case remains higher in the region of 85 MPa while the walking load case induces around 40 MPa. The stress range in the straight and single taper stem prosthesis is lower than 260 MPa, while localized Tresca stress is in the order of the yield strength of Ti-6Al-4V alloy for double and triple taper stem design.

  1. Effects of Prosthesis Stem Tapers on Stress Distribution of Cemented Hip Arthroplasty

    NASA Astrophysics Data System (ADS)

    Abdullah, Abdul Halim; Nor, Mohd Asri Mohd; Saman, Alias Mohd; Tamin, Mohd Nasir; Kadir, Mohammed Rafiq Abdul

    2010-10-01

    Aseptic loosening effects are critical issues in encouraging long term stability of cemented hip arthroplasty. Stress shielding is believed to be an important factor that contributes to the aseptic loosening problems. The numerous changes in the prosthesis stem design are intended to minimize the stress shielding and aseptic loosening problems and to improve the long term performance of the implants. In this study, the stress distribution in cemented hip arthroplasty is established using finite element method. The taper of the prosthesis is designed to be 3° at anterior/posterior, 3° at medial/lateral and 10° from wide lateral to narrow medial. Major muscle loads and contact forces are simulated for walking (toe-off phase) and stair climbing load cases. Effects of prosthesis stem tapers on the resulting stress distribution are investigated. Results show that compressive stress dominates in the medial plane while tensile stress in the lateral plane of the femur. The corresponding stress levels of intact femur for walking and stair-climbing load cases are 22 and 29 MPa, respectively. The magnitude of Tresca stress for the THA femur in stair-climbing load case remains higher in the region of 85 MPa while the walking load case induces around 40 MPa. The stress range in the straight and single taper stem prosthesis is lower than 260 MPa, while localized Tresca stress is in the order of the yield strength of Ti-6Al-4V alloy for double and triple taper stem design.

  2. Risk Factors for Subsidence of a Modular Tapered Femoral Stem Used for Revision Total Hip Arthroplasty.

    PubMed

    Tangsataporn, Suksan; Safir, Oleg A; Vincent, Alexander D; Abdelbary, Hesham; Gross, Allan E; Kuzyk, Paul R T

    2015-06-01

    The purpose of this study was to determine the incidence, and the clinical and radiographic risk factors for significant subsidence of a cementless, modular tapered revision femoral stem. Femoral stem subsidence of at least 10 mm or subsidence requiring revision was considered significant subsidence. Ninety-seven patients (99 hips) were included with minimum radiographic follow-up of one year (mean 34 months; range, 12-91 months). The mean stem subsidence was 4.5 mm (range, 0-44 mm). Fourteen out of 99 (14.1%) stems had significant subsidence and 6 (6.1%) stems required revision due to subsidence. Patient weight greater than 80 kg (P=0.04) and femoral stem press-fit distance of less than 2 cm (P<0.01) were both independent risk factors for significant stem subsidence.

  3. Femoral revision with taper stems: results at ten years follow-up.

    PubMed

    Cherubino, Paolo; Fagetti, Alessandro; D'Angelo, Fabio; Surace, Michele Francesco

    2010-10-01

    In the case of extensively damaged meta-diaphyseal femoral bone with cortices thinning and widened femoral canal, tapered stems allow a good primary fixation and early weight-bearing. A retrospective review was conducted to evaluate long-term results of modular revision taper stems implanted from March 1999 to December 2002. Sixty-five consecutive hip revision surgeries were performed, mostly for aseptic loosening (75% of the cases). Femoral bone stock defects were classified according to AAOS's criteria and consisted mainly in type II (cavitary defects, 44.6%) and type III (combined defects, 33.9%). A trochanteric osteotomy was performed in 25 cases (38%) to remove primary implants that were cemented in 35 cases (54%). The mean postoperative follow-up was 109 months (range, 76 to 131 months). Clinical assessment at follow-up showed a significantly improved mean Harris Hip Score from 42 points preoperatively to 81 points postoperatively, while the x-ray examination did show a satisfactory distal integration of the stem in all cases and satisfactory reconstitution of the femoral bone stock in 47% of cases. The average subsidence of the stem at follow-up was less than one millimeter. According to data analysis, a leg-length discrepancy exceeding 15 millimeters caused significantly worse functional outcome and pain.

  4. Corrosion of the Head-Stem Taper Junction-Are We on the Verge of an Epidemic?: Review Article.

    PubMed

    Morlock, Michael; Bünte, Dennis; Gührs, Julian; Bishop, Nicholas

    2017-02-01

    The modular head taper junction has contributed to the success of total hip arthroplasty (THA) greatly. Taper corrosion and wear problems reported for large and extra-large metal-on-metal bearings as well as for bi-modular THA stems have cast doubt on the benefit of the taper interface. Presently, corrosion problems are being reported for nearly all kinds of artificial hip joints incorporating metal heads, questioning taper connections in general. This study aimed to review the mechanical and electrochemical relationships that may lead to taper corrosion, which have been reported more commonly in recent literature, and to also review the contribution of patient characteristics and surgical techniques involved in taper assembly that may contribute to the problem. The search criteria "(corrosion) AND (hip arthroplasty) AND (taper OR trunnion)" and "(hip arthroplasty) AND ((pseudotumor) OR (pseudo-tumor))" in PubMed and the JAAOS were used for the literature search. In addition, the arthroplasty registers were considered. Most studies acknowledge the multifactorial nature of the problem but concentrate their analysis on taper and implant design aspects, since this is the only factor that can be easily quantified. The sometimes conflicting results in the literature could be due to the fact that the other two decisive factors are not sufficiently considered: the loading situation in the patient and the assembly situation by the surgeon. All three factors together determine the fate of a taper junction in THA. There is no single reason as a main cause for taper corrosion. The combined "outcome" of these three factors has to be in a "safe range" to achieve a successful long-term taper fixation. No, this is not the beginning of an epidemic. It is rather the consequence of disregarding known mechanical and electrochemical relationships, which in combination have recently caused a more frequent occurrence-and mainly reporting-of corrosion issues.

  5. Development of a stem taper equation and modelling the effect of stand density on taper for Chinese fir plantations in Southern China

    PubMed Central

    Zhang, Sensen; Zhang, Xiongqing

    2016-01-01

    Chinese fir (Cunninghamia lanceolata) is the most important commercial tree species in southern China. The objective of this study was to develop a variable taper equation for Chinese fir, and to quantify the effects of stand planting density on stem taper in Chinese fir. Five equations were fitted or evaluated using the diameter-height data from 293 Chinese fir trees sampled from stands with four different densities in Fenyi County, Jiangxi Province, in southern China. A total of 183 trees were randomly selected for the model development, with the remaining 110 trees used for model evaluation. The results show that the Kozak’s, Sharma/Oderwald, Sharma/Zhang and modified Brink’s equations are superior to the Pain/Boyer equation in terms of the fitting and validation statistics, and the modified Brink’s and Sharma/Zhang equations should be recommended for use as taper equations for Chinese fir because of their high accuracy and variable exponent. The relationships between some parameters of the three selected equations and stand planting densities can be built by adopting some simple mathematical functions to examine the effects of stand planting density on tree taper. The modelling and prediction precision of the three taper equations were compared with or without incorporation of the stand density variable. The predictive accuracy of the model was improved by including the stand density variable and the mean absolute bias of the modified Brink’s and Sharma/Zhang equations with a stand density variable were all below 1.0 cm in the study area. The modelling results showed that the trees have larger butt diameters and more taper when stand density was lower than at higher stand density. PMID:27168964

  6. Fitting and Calibrating a Multilevel Mixed-Effects Stem Taper Model for Maritime Pine in NW Spain

    PubMed Central

    Arias-Rodil, Manuel; Castedo-Dorado, Fernando; Cámara-Obregón, Asunción; Diéguez-Aranda, Ulises

    2015-01-01

    Stem taper data are usually hierarchical (several measurements per tree, and several trees per plot), making application of a multilevel mixed-effects modelling approach essential. However, correlation between trees in the same plot/stand has often been ignored in previous studies. Fitting and calibration of a variable-exponent stem taper function were conducted using data from 420 trees felled in even-aged maritime pine (Pinus pinaster Ait.) stands in NW Spain. In the fitting step, the tree level explained much more variability than the plot level, and therefore calibration at plot level was omitted. Several stem heights were evaluated for measurement of the additional diameter needed for calibration at tree level. Calibration with an additional diameter measured at between 40 and 60% of total tree height showed the greatest improvement in volume and diameter predictions. If additional diameter measurement is not available, the fixed-effects model fitted by the ordinary least squares technique should be used. Finally, we also evaluated how the expansion of parameters with random effects affects the stem taper prediction, as we consider this a key question when applying the mixed-effects modelling approach to taper equations. The results showed that correlation between random effects should be taken into account when assessing the influence of random effects in stem taper prediction. PMID:26630156

  7. Fitting and Calibrating a Multilevel Mixed-Effects Stem Taper Model for Maritime Pine in NW Spain.

    PubMed

    Arias-Rodil, Manuel; Castedo-Dorado, Fernando; Cámara-Obregón, Asunción; Diéguez-Aranda, Ulises

    2015-01-01

    Stem taper data are usually hierarchical (several measurements per tree, and several trees per plot), making application of a multilevel mixed-effects modelling approach essential. However, correlation between trees in the same plot/stand has often been ignored in previous studies. Fitting and calibration of a variable-exponent stem taper function were conducted using data from 420 trees felled in even-aged maritime pine (Pinus pinaster Ait.) stands in NW Spain. In the fitting step, the tree level explained much more variability than the plot level, and therefore calibration at plot level was omitted. Several stem heights were evaluated for measurement of the additional diameter needed for calibration at tree level. Calibration with an additional diameter measured at between 40 and 60% of total tree height showed the greatest improvement in volume and diameter predictions. If additional diameter measurement is not available, the fixed-effects model fitted by the ordinary least squares technique should be used. Finally, we also evaluated how the expansion of parameters with random effects affects the stem taper prediction, as we consider this a key question when applying the mixed-effects modelling approach to taper equations. The results showed that correlation between random effects should be taken into account when assessing the influence of random effects in stem taper prediction.

  8. Simple taper: Taper equations for the field forester

    Treesearch

    David R. Larsen

    2017-01-01

    "Simple taper" is set of linear equations that are based on stem taper rates; the intent is to provide taper equation functionality to field foresters. The equation parameters are two taper rates based on differences in diameter outside bark at two points on a tree. The simple taper equations are statistically equivalent to more complex equations. The linear...

  9. Asymptomatic Pseudotumors in Patients with Taper Corrosion of a Dual-Taper Modular Femoral Stem: MARS-MRI and Metal Ion Study.

    PubMed

    Kwon, Young-Min; Khormaee, Sariah; Liow, Ming Han Lincoln; Tsai, Tsung-Yuan; Freiberg, Andrew A; Rubash, Harry E

    2016-10-19

    Modularity in total hip arthroplasty facilitates intraoperative restoration of patient anatomy. Although dual-taper modular total hip arthroplasty offers potential advantages for optimizing the hip center of rotation, it has been associated with modular taper corrosion. This corrosion has led to adverse local tissue reactions (pseudotumors) at the neck-stem junction and elevated metal-ion levels. However, the occurrence of taper-corrosion-related pseudotumors in patients who remain asymptomatic following total hip arthroplasty with a dual-taper modular femoral stem remains largely unknown. The aims of this study were (1) to determine the prevalence of asymptomatic pseudotumors by utilizing metal artifact reduction sequence magnetic resonance imaging (MARS-MRI) and (2) compare serum metal-ion levels between symptomatic and asymptomatic patients with a dual-taper modular stem total hip replacement. We performed a retrospective cross-sectional study of 97 consecutive patients who had been treated with a dual-taper modular femoral stem total hip arthroplasty. Eighty-three patients were stratified into symptomatic and asymptomatic groups and evaluated with MARS-MRI, measurement of serum metal-ion levels, and the University of California at Los Angeles (UCLA) functional hip score. The prevalence of pseudotumors as determined with MARS-MRI was 15% in our asymptomatic patients and 36% in the overall cohort. The median serum cobalt level and cobalt/chromium ratio were significantly higher in patients with a pseudotumor than in those without a pseudotumor (8.0 versus 2.0 μg/L [p = 0.004] and 10.3 versus 2.4 μg/L [p = 0.012], respectively). However, there was no significant difference in the serum cobalt level or cobalt/chromium ratio between symptomatic patients with a pseudotumor and asymptomatic patients with a pseudotumor (7.6 versus 6.2 μg/L [p = 0.37] and 8.3 versus 10.6 μg/L [p = 0.46], respectively). The UCLA scores of asymptomatic patients with a pseudotumor were

  10. Distal fixation of proximally coated tapered stems may predispose to a failure of osteointegration.

    PubMed

    Cooper, H John; Jacob, Anitha P; Rodriguez, José A

    2011-09-01

    Despite excellent long-term results of proximally coated tapered wedge femoral stems in noncemented total hip arthroplasty, we have consistently observed a minority fail to achieve osteointegration. We retrospectively reviewed 320 consecutive total hip arthroplasties performed by a single surgeon using a single stem over a 4-year period. Clinical and radiographic parameters were analyzed for risk factors predisposing to a failure of osteointegration, defined as a progressive circumferential radiolucency around the proximal porous coating on both anteroposterior and lateral radiographs. Fifteen stems (4.7%) failed to osteointegrate; 3 underwent femoral revision for persistent thigh pain, whereas the remainder expressed varying degrees of symptomatology. Risk factors associated with failure of osteointegration were male sex, a smaller canal-flare index, larger stem size, and greater canal fill at the mid- and distal-thirds of the stem. Awareness of variability in proximal femoral morphology and problems caused by distal fixation with a proximally coated implant may help avoid this uncommon but potentially serious complication. Copyright © 2011. Published by Elsevier Inc.

  11. Elevated Serum Titanium Level as a Marker for Failure in a Titanium Modular Fluted Tapered Stem.

    PubMed

    McAlister, Ian P; Abdel, Matthew P

    2016-07-01

    Serum ion concentrations of cobalt and chromium are commonly used to monitor for the development of local metal reactions in metal-on-metal total hip arthroplasties, as well as dual-modular constructs. Although rarely used in clinical practice, elevated serum titanium levels have the ability to indicate a failure with contemporary revision constructs, such as with titanium modular fluted tapered (TMFT) stems. The authors report the case of a 64-year-old man with a TMFT stem after revision total hip arthroplasty for a dual-modular neck construct who had set screw disengagement with subsequent proximal body loosening. The patient's serum cobalt and chromium levels were normal, but he had a markedly elevated serum titanium level, indicating failure of the titanium modular junction. Implant failures at modular junctions in femoral components are well described. Although several different failure mechanisms have been defined, to the authors' knowledge this is the first reported failure of this particular TMFT stem. In addition, this is the first report describing the use of serum titanium levels in identifying a novel failure mechanism. With the popularity of this stem, surgeons should be aware that an elevated serum titanium level may aid in the diagnosis of this unique complication. [Orthopedics. 2016; 39(4):e768-e770.].

  12. "Top-Out" Removal of Well-Fixed Dual-Taper Femoral Stems: Surgical Technique and Radiographic Risk Factors.

    PubMed

    Kwon, Young-Min; Antoci, Valentin; Eisemon, Eric; Tsai, Tsung-Yuan; Yan, Yu; Liow, Ming Han Lincoln

    2016-12-01

    Contemporary "dual-taper" modular femoral neck-stem designs have been associated with taper corrosion-related adverse local tissue reaction (ALTR) requiring revision surgery and stem removal. Extended trochanteric osteotomy is recognized as the workhorse procedure for revision hip surgery. The aim of our study is to describe our "top-out" stem removal surgical technique and identify preoperative radiographic risk factors associated with periprosthetic fractures when using this technique. This is a single-center, single-surgeon, retrospective case series. Operative and clinic records were reviewed for patients with dual-taper modular femoral neck-stem junction who underwent revision surgery for taper tribocorrosion-related ALTR. Eighty-three patients (36 men and 47 women; mean age, 61.8 ± 10.3; body mass index, 30.2 ± 8.6) were revised using the top-out technique. Significant improvements in postoperative Harris hip score (P = .004), EuroQol 5-dimension questionnaire (EQ-5D; P < .001), and EQ-5D US-adjusted scores (P < .001) were observed at 19-months follow-up. Our study reports periprosthetic fracture incidence of 14% and reoperation rate of 7%. Periprosthetic fractures were positively correlated with radiographic parameters such as overhang distance (R = 0.376; P = .002) and overhang ratio (R = 0.312; P = .01) and negatively correlated with radiographic implant medial calcar prominence (R = -0.299; P = .01). Removal of well-fixed femoral components can be challenging, and the burden of revision surgery for taper tribocorrosion-related ALTR of these femoral stems is likely to rise. A top-out technique with systematic preoperative planning with radiographs provides a viable, alternative surgical option to remove well-fixed femoral component while preserving the femoral bony envelope. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Effect of femoral canal shape on mechanical stress distribution and adaptive bone remodelling around a cementless tapered-wedge stem.

    PubMed

    Oba, M; Inaba, Y; Kobayashi, N; Ike, H; Tezuka, T; Saito, T

    2016-09-01

    In total hip arthroplasty (THA), the cementless, tapered-wedge stem design contributes to achieving initial stability and providing optimal load transfer in the proximal femur. However, loading conditions on the femur following THA are also influenced by femoral structure. Therefore, we determined the effects of tapered-wedge stems on the load distribution of the femur using subject-specific finite element models of femurs with various canal shapes. We studied 20 femurs, including seven champagne flute-type femurs, five stovepipe-type femurs, and eight intermediate-type femurs, in patients who had undergone cementless THA using the Accolade TMZF stem at our institution. Subject-specific finite element (FE) models of pre- and post-operative femurs with stems were constructed and used to perform FE analyses (FEAs) to simulate single-leg stance. FEA predictions were compared with changes in bone mineral density (BMD) measured for each patient during the first post-operative year. Stovepipe models implanted with large-size stems had significantly lower equivalent stress on the proximal-medial area of the femur compared with champagne-flute and intermediate models, with a significant loss of BMD in the corresponding area at one year post-operatively. The stovepipe femurs required a large-size stem to obtain an optimal fit of the stem. The FEA result and post-operative BMD change of the femur suggest that the combination of a large-size Accolade TMZF stem and stovepipe femur may be associated with proximal stress shielding.Cite this article: M. Oba, Y. Inaba, N. Kobayashi, H. Ike, T. Tezuka, T. Saito. Effect of femoral canal shape on mechanical stress distribution and adaptive bone remodelling around a cementless tapered-wedge stem. Bone Joint Res 2016;5:362-369. DOI: 10.1302/2046-3758.59.2000525. © 2016 Yutaka et al.

  14. Effect of femoral canal shape on mechanical stress distribution and adaptive bone remodelling around a cementless tapered-wedge stem

    PubMed Central

    Oba, M.; Kobayashi, N.; Ike, H.; Tezuka, T.; Saito, T.

    2016-01-01

    Objectives In total hip arthroplasty (THA), the cementless, tapered-wedge stem design contributes to achieving initial stability and providing optimal load transfer in the proximal femur. However, loading conditions on the femur following THA are also influenced by femoral structure. Therefore, we determined the effects of tapered-wedge stems on the load distribution of the femur using subject-specific finite element models of femurs with various canal shapes. Patients and Methods We studied 20 femurs, including seven champagne flute-type femurs, five stovepipe-type femurs, and eight intermediate-type femurs, in patients who had undergone cementless THA using the Accolade TMZF stem at our institution. Subject–specific finite element (FE) models of pre- and post-operative femurs with stems were constructed and used to perform FE analyses (FEAs) to simulate single-leg stance. FEA predictions were compared with changes in bone mineral density (BMD) measured for each patient during the first post-operative year. Results Stovepipe models implanted with large-size stems had significantly lower equivalent stress on the proximal-medial area of the femur compared with champagne-flute and intermediate models, with a significant loss of BMD in the corresponding area at one year post-operatively. Conclusions The stovepipe femurs required a large-size stem to obtain an optimal fit of the stem. The FEA result and post-operative BMD change of the femur suggest that the combination of a large-size Accolade TMZF stem and stovepipe femur may be associated with proximal stress shielding. Cite this article: M. Oba, Y. Inaba, N. Kobayashi, H. Ike, T. Tezuka, T. Saito. Effect of femoral canal shape on mechanical stress distribution and adaptive bone remodelling around a cementless tapered-wedge stem. Bone Joint Res 2016;5:362–369. DOI: 10.1302/2046-3758.59.2000525. PMID:27601435

  15. A Compatible Stem Taper-Volume-Weight System For Intensively Managed Fast Growing Loblolly Pine

    Treesearch

    Yugia Zhang; Bruce E. Borders; Robert L Bailey

    2002-01-01

    eometry-oriented methodology yielded a compatible taper-volume-weight system of models whose parameters were estimated using data from intensively managed loblolly pine (Pinus taeda L.) plantations in the lower coastal plain of Georgia. Data analysis showed that fertilization has significantly reduced taper (inside and outside bark) on the upper...

  16. Successful femoral reconstruction with a fluted and tapered modular distal fixation stem in revision total hip arthroplasty.

    PubMed

    Skyttä, E T; Eskelinen, A; Remes, V

    2012-01-01

    Early results of fluted and tapered distal fixation stems used in reconstruction of deficient femora in femoral revision arthroplasty have been successful in small series. We evaluated the survival of the LINK MP Reconstruction Hip Stem and factors associated with survival using data from a nation-wide arthroplasty register. 408 femoral revisions using LINK MP Reconstruction Hip Stem were performed during 1994 to 2007. The mean age of the patients was 72.5 (range: 36-93) years and 63% were performed in women. Kaplan-Meier analysis and the Cox regression model were used for the survival analysis. The effects of age, sex and diagnoses were also studied. The 9-year overall survivorship for the LINK MP Reconstruction Hip Stem was 75% (95% CI 70-80). Aseptic loosening was rare; the 9-year revision rate for aseptic loosening was only 3%, which coincides with earlier reports with shorter folllow-up. The most common reason for re-revision was dislocation of the prosthesis with or without malposition of the socket (67%). Indication for revision strongly affected the survival rate with revisions for dislocation having an over 3-fold and revisions for infection a 3-fold relative risk for re-revision compared to revisions for aseptic loosening. Increasing age slightly decreased the risk of re-revision but sex did not affect the survival. Based on our findings, we conclude LINK MP Reconstruction Hip Stem, as an example of a fluted and tapered distal fixation stem, appears to solve many problems with implant fixation in femoral revisions. High number of dislocations suggests that special attention should be paid to correct center of rotation, to correct implant positioning and to need of constrained implants in case of deficient abductor mechanism.

  17. High survival of modular tapered stems for proximal femoral bone defects at 5 to 10 years followup.

    PubMed

    Van Houwelingen, Andrew P; Duncan, Clive P; Masri, Bassam A; Greidanus, Nelson V; Garbuz, Donald S

    2013-02-01

    Currently, the two most commonly used options for the revision of femoral components in North America are: cylindrical, nonmodular, cobalt-chromium stems and tapered, fluted, modular, titanium (TFMT) stems. Previous reports have cited high failure rates with cylindrical cobalt chrome stems in large femoral defects but the longer term survival of the fluted stems is unknown. We examined the 5- to 10-year survival of TFMT stems implanted for severe femoral defects. We reviewed all 65 patients with severe proximal bone defects revised with the TMFT stem between January 2000 and 2006. Ten were lost to followup and seven were dead, leaving 48 patients for followup at 5 to 10 years (mean, 84 months; range, 60-120 months). All patients completed five quality-of-life (QOL) questionnaires. Radiographs were evaluated for loosening, subsidence, and preservation of proximal host bone stock. Implant survivorship was 90%. No patient underwent revision for either subsidence or loosening. Subsidence occurred in seven patients (average, 12.3 mm) but all achieved secondary stability. Five patients underwent revision as a result of fracture of the stem and all had the original standard stem design, which has since been modified. All five implant fractures occurred at the modular stem junction. Mean QOL outcomes were: WOMAC = 81 (pain), Oxford = 75, SF-12 = 54 (mental) and 38 (physical), UCLA Activity = 4, and satisfaction overall = 73. Midterm survivorship of modular titanium stems in large femoral defects is high; however, ongoing surveillance of stem junctional fatigue life is required. Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

  18. Assembly force and taper angle difference influence the relative motion at the stem-neck interface of bi-modular hip prostheses.

    PubMed

    Haschke, Henning; Jauch-Matt, Sabrina Y; Sellenschloh, Kay; Huber, Gerd; Morlock, Michael M

    2016-07-01

    Bi-modular hip arthroplasty prostheses allow adaptation to the individual patient anatomy and the combination of different materials but introduce an additional interface, which was related lately to current clinical issues. Relative motion at the additional taper interface might increase the overall risk of fretting, corrosion, metallic debris and early failure. The aim of this study was to investigate whether the assembly force influences the relative motion and seating behaviour at the stem-neck interface of a bi-modular hip prosthesis (Metha(®); Aesculap AG, Tuttlingen, Germany) and whether this relation is influenced by the taper angle difference between male and female taper angles. Neck adapters made of titanium (Ti6Al4V) and CoCr (CoCr29Mo) were assembled with a titanium stem using varying assembly forces and mechanically loaded. A contactless eddy current measurement system was used to record the relative motion between prosthesis stem and neck adapter. Higher relative motion was observed for Ti neck adapters compared to the CoCr ones (p < 0.001). Higher assembly forces caused increased seating distances (p < 0.001) and led to significantly reduced relative motion (p = 0.019). Independent of neck material type, prostheses with larger taper angle difference between male and female taper angles exhibited decreased relative motion (p < 0.001). Surgeons should carefully use assembly forces above 4 kN to decrease the amount of relative motion within the taper interface. Maximum assembly forces, however, should be limited to prevent periprosthetic fractures. Manufacturers should optimize taper angle differences to increase the resistance against relative motion. © IMechE 2016.

  19. Chemical composition of needles and cambial activity of stems of Scots pine trees affected by air pollutants in Polish forests

    Treesearch

    Wojciech Dmuchowski; Ewa U. Kurczynska; Wieslaw Wloch

    1998-01-01

    The impact of environmental pollution is defined for the chemical composition of Scots pine (Pinus sylvestris L.) needles and cambial activity in the tree stems in Polish forests. The research investigated 20-year-old trees growing in two areas in significantly different levels of pollution. The highly polluted area was located near the Warsaw...

  20. Congenital hip dysplasia treated by total hip arthroplasty using cementless tapered stem in patients younger than 50 years old: results after 12-years follow-up.

    PubMed

    Faldini, Cesare; Miscione, Maria Teresa; Chehrassan, Mohammadreza; Acri, Francesco; Pungetti, Camilla; d'Amato, Michele; Luciani, Deianira; Giannini, Sandro

    2011-12-01

    Congenital hip dysplasia may lead to severe acetabular and femoral abnormalities that can make total hip arthroplasty a challenging procedure. We assessed a series of patients affected by developmental hip dysplasia treated with total hip arthroplasty using cementless tapered stem and here we report the outcomes at long-term follow-up. Twenty-eight patients (24 women and 4 men) aged between 44 and 50 years (mean 47 years) were observed. Clinical evaluation was rated with the Harris Hip Score. Radiographic evaluation consisted in standard anteroposterior and axial view radiographs of the hip. According to Crowe's classification, 16 hips presented dysplasia grade 1, 14 grade 2, and 4 grade 3. All patients were treated with total hip arthroplasty using a cementless tapered stem (Wagner Cone Prosthesis). Six patients were operated bilaterally, with a totally of 34 hips operated. After surgery, the patients were clinically and radiographically checked at 3, 6, and 12 months and yearly thereafter until an average follow-up of 12 years (range 10-14 years). Average Harris Hip Score was 56 ± 9 (range 45-69) preoperatively, 90 ± 9 (range 81-100) 12 months after surgery, and 91 ± 8 (range 83-100) at last follow-up. Radiographic evaluation demonstrated excellent osteointegration of the implants. Signs of bone resorption were present in 6 hips, nevertheless no evidence of loosening was observed and none of the implants has been revised. Even in dysplasic femur, the tapered stem allowed adequate stability and orientation of the implant. We consider tapered stem a suitable option for total hip arthroplasty in developmental hip dysplasia, also in case of young patients, thanks to the favourable long-term results.

  1. In vivo oxide-induced stress corrosion cracking of Ti-6Al-4V in a neck-stem modular taper: Emergent behavior in a new mechanism of in vivo corrosion.

    PubMed

    Gilbert, Jeremy L; Mali, Sachin; Urban, Robert M; Silverton, Craig D; Jacobs, Joshua J

    2012-02-01

    In vivo modular taper corrosion in orthopedic total joint replacements has been documented to occur for head-neck tapers, modular-body tapers, and neck-stem tapers. While the fretting corrosion mechanism by which this corrosion occurs has been described in the literature, this report shows new and as yet unreported mechanisms at play. A retrieved Ti-6Al-4V/Ti-6Al-4V neck-stem taper interface, implanted for 6 years is subjected to failure analysis to document taper corrosion processes that lead to oxide driven crack formation on the medial side of the taper. Metallurgical sectioning techniques and scanning electron microscopy analysis are used to document the taper corrosion processes. The results show large penetrating pitting attack of both sides of the taper interface where corrosion selectively attacks the beta phase of the microstructure and eventually consumes the alpha phase. The pitting attack evolves into plunging pits that ultimately develop into cracks where the crack propagation process is one of corrosion resulting in oxide formation and subsequent reorganization. This process drives open the crack and advances the front by a combination of oxide-driven crack opening stresses and corrosion attack at the tip. The oxide that forms has a complex evolving structure including a network of transport channels that provide access of fluid to the crack tip. This emergent behavior does not appear to require continued fretting corrosion to propagate the pitting and cracking. This new mechanism is similar to stress corrosion cracking where the crack tip stresses arise from the oxide formation in the crack and not externally applied tensile stresses. Copyright © 2011 Wiley Periodicals, Inc.

  2. Tapered stems one-third proximally coated have higher complication rates than cylindrical two-third coated stems in patients with high hip dislocation undergoing total hip arthroplasty with step-cut shortening osteotomy.

    PubMed

    Ozden, V Emre; Dikmen, G; Beksac, B; Tozun, I Remzi

    2017-06-01

    The results of cementless stems in total hip arthroplasty (THA) done because of congenital dislocation with step-cut osteotomy is not well known, particularly the influence of the design and the role of extent of porous coating. Therefore we performed a retrospective study to evaluate the mid to long-term results THA performed with a single type acetabular component and different geometry and fixation type stems with ceramic bearings in the setting of step-cut subtrochanteric osteotomy in high hip dislocated (HHD) patients. We asked if the stem type affect the outcomes in terms of (1) intra and postoperative complication rates (2) radiographic outcomes (3) prosthesis survival in step-cut subtrochanteric shortening osteotomy. The type of the stem, whether cylindrical or tapered does not affect the outcome if the femoral canal fit and fill is obtained and the step-cut femoral shortening osteotomy is primarily fixed. Forty-five hips in 35 patients with a mean follow up of 10 years (range, 7-14 years) were evaluated. The single type cementless cup was placed at the level of the true acetabulum, a step-cut shortening femoral osteotomy was performed and reconstruction was performed with two different types of tapered stem in twenty-two hips (Synergy™ and Image™ proximally coated, Smith and Nephew, Menphis, TN, USA) and one type of cylindrical stem (Echelon™ with 2/3 coated, Smith and Nephew, Menphis, TN, USA) in twenty-three hips. Harris hip scores (HHS) and a University of California Los Angeles (UCLA) activity scores were calculated for all patients and successive X-rays were evaluated regarding component loosening and osteolysis, along with complications related to bearing, step-cut osteotomy and stem types. Forty-one hips (91%) had good and excellent clinical outcome according to HHS. The mean UCLA activity scores improved from 3.2±0.6 points (range, 2-4) preoperatively to 6.3 points±0.5 (range, 5-7) at the latest follow-up. The mean femoral shortening was 36

  3. Tapered triumph

    NASA Astrophysics Data System (ADS)

    2009-01-01

    German company M2K Laser was the first in the world to successfully commercialize tapered diode lasers, and is currently the only one making gallium antimonide devices. The company's managing director speaks to Nadya Anscombe about its strategy and future.

  4. Adverse Local Tissue Reaction Arising from Corrosion at the Femoral Neck-Body Junction in a Dual-Taper Stem with a Cobalt-Chromium Modular Neck

    PubMed Central

    Cooper, H. John; Urban, Robert M.; Wixson, Richard L.; Meneghini, R. Michael; Jacobs, Joshua J.

    2013-01-01

    Background: Femoral stems with dual-taper modularity were introduced to allow additional options for hip-center restoration independent of femoral fixation in total hip arthroplasty. Despite the increasing availability and use of these femoral stems, concerns exist about potential complications arising from the modular neck-body junction. Methods: This was a multicenter retrospective case series of twelve hips (eleven patients) with adverse local tissue reactions secondary to corrosion at the modular neck-body junction. The cohort included eight women and three men who together had an average age of 60.1 years (range, forty-three to seventy-seven years); all hips were implanted with a titanium-alloy stem and cobalt-chromium-alloy neck. Patients presented with new-onset and increasing pain at a mean of 7.9 months (range, five to thirteen months) following total hip arthroplasty. After serum metal-ion studies and metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) revealed abnormal results, the patients underwent hip revision at a mean of 15.2 months (range, ten to twenty-three months). Tissue specimens were examined by a single histopathologist, and the retrieved implants were studied with use of light and scanning electron microscopy. Results: Serum metal levels demonstrated greater elevation of cobalt (mean, 6.0 ng/mL) than chromium (mean, 0.6 ng/mL) or titanium (mean, 3.4 ng/mL). MRI with use of MARS demonstrated adverse tissue reactions in eight of nine patients in which it was performed. All hips showed large soft-tissue masses and surrounding tissue damage with visible corrosion at the modular femoral neck-body junction. Available histology demonstrated large areas of tissue necrosis in seven of ten cases, while remaining viable capsular tissue showed a dense lymphocytic infiltrate. Microscopic analysis was consistent with fretting and crevice corrosion at the modular neck-body interface. Conclusions: Corrosion at the modular neck

  5. Adverse local tissue reaction arising from corrosion at the femoral neck-body junction in a dual-taper stem with a cobalt-chromium modular neck.

    PubMed

    Cooper, H John; Urban, Robert M; Wixson, Richard L; Meneghini, R Michael; Jacobs, Joshua J

    2013-05-15

    Femoral stems with dual-taper modularity were introduced to allow additional options for hip-center restoration independent of femoral fixation in total hip arthroplasty. Despite the increasing availability and use of these femoral stems, concerns exist about potential complications arising from the modular neck-body junction. This was a multicenter retrospective case series of twelve hips (eleven patients) with adverse local tissue reactions secondary to corrosion at the modular neck-body junction. The cohort included eight women and three men who together had an average age of 60.1 years (range, forty-three to seventy-seven years); all hips were implanted with a titanium-alloy stem and cobalt-chromium-alloy neck. Patients presented with new-onset and increasing pain at a mean of 7.9 months (range, five to thirteen months) following total hip arthroplasty. After serum metal-ion studies and metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) revealed abnormal results, the patients underwent hip revision at a mean of 15.2 months (range, ten to twenty-three months). Tissue specimens were examined by a single histopathologist, and the retrieved implants were studied with use of light and scanning electron microscopy. Serum metal levels demonstrated greater elevation of cobalt (mean, 6.0 ng/mL) than chromium (mean, 0.6 ng/mL) or titanium (mean, 3.4 ng/mL). MRI with use of MARS demonstrated adverse tissue reactions in eight of nine patients in which it was performed. All hips showed large soft-tissue masses and surrounding tissue damage with visible corrosion at the modular femoral neck-body junction. Available histology demonstrated large areas of tissue necrosis in seven of ten cases, while remaining viable capsular tissue showed a dense lymphocytic infiltrate. Microscopic analysis was consistent with fretting and crevice corrosion at the modular neck-body interface. Corrosion at the modular neck-body junction in dual-tapered stems with a modular

  6. Prospective two-year subsidence analysis of 100 cemented polished straight stems - a short-term clinical and radiological observation.

    PubMed

    Siepen, Wolf; Zwicky, Lukas; Stoffel, Karl Kilian; Ilchmann, Thomas; Clauss, Martin

    2016-09-17

    Cemented stems show good long-term results and the survival of new implants can be predicted by their early subsidence. With EBRA-FCA (Femoral Component Analysis using Einzel-Bild-Röntgen-Analyse) early subsidence as an early indicator for later aseptic loosening can be analysed. For the cemented TwinSys stem mid- and long-term data is only avalible from the New Zeeland Arthroplasty register, thus close monitoring of this implant system is still mandatory. We conducted a 2 year follow up of 100 consecutive hybrid THA (Total hip arthroplasty) of a series of 285 primary THA operated between Jan 2009 und Oct 2010. These 100 received a polished, cemented collarless straight stem (twinSys®, Mathys AG® Bettlach, Switzerland) with an uncemented monobloc pressfit cup (RM pressfit®, Mathys AG® Bettlach, Switzerland). The other patients were treated with the uncemented version of this stem and the same cup. Clinical (Harris Hip Score) and radiological (ap and axial x-rays, cementing quality according to Barrack, alignment) outcomes besides an EBRA-FCA subsidence analysis were performed. Median age at operation was 78 (68 to 93) years. 5 patients died in the course of follow-up unrelated to surgery. The KM (Kaplan-Meier) survival at 2 years for the endpoint reoperation for any reason was 94.9 (95 % confidence interval 90.6-100 %). Survival for the endpoint aseptic loosening at 2 years was 100 %. The HHS (Harris Hip Score) improved from 56 (14-86) preoperatively to 95 (60-100) 2 years after the operation. Cementing results were judged 47 % Grade A, 45 % Grade B and 7 % Grade C. Osteolysis was found in 2 stems without clinical symptoms or correlation to subsidence or cementing quality. The EBRA-FCA analysis showed an average subsidence of -0.30 mm (95 % CI -0.5 mm to -0.1 mm). 11 patients showed a subsidence of more than 1 mm. In this group one patient showed a subsidence of 1.5 mm and one of 3.1 mm without further radiological changes. The twinSys stem

  7. Simple, Flexible, Trigonometric Taper Equations

    Treesearch

    Charles E. Thomas; Bernard R. Parresol

    1991-01-01

    There have been numerous approaches to modeling stem form in recent decades. The majority have concentrated on the simpler coniferous bole form and have become increasingly complex mathematical expressions. Use of trigonometric equations provides a simple expression of taper that is flexible enough to fit both coniferous and hard-wood bole forms. As an illustration, we...

  8. A comparison of subsidence of Exeter standard and long stems.

    PubMed

    Davis, Edward T; Heaver, Catriona E; Pynsent, Paul B; Pearson, Andrew M; Treacy, Ronan B C

    2010-01-01

    The survivorship of the polished, double taper Exeter stem is related to subsidence within the cement mantle. Long Exeter stems have altered geometry which may influence subsidence characteristics. Using digitised x-rays and appropriate computer software we measured the subsidence of 35 standard and 40 long stem Exeter implants. Measurements were taken from initial postoperative radiographs and repeated at intervals up to 5 years. Long stem implants were used in cemented revisions without the use of impaction bone grafting. Subsidence rates of the standard length stems in our study were comparable to that in published literature. Long stems did not replicate this subsidence pattern and had subsided less at 6, 12 and 24 months. However, the 205mm long stem, which has a fully tapered design, did follow the subsidence characteristics of the standard stem. Subsidence of long stem Exeter implants does not mirror that of the standard length stem. Loss of the fully tapered geometry of the longer stem implants may account for this finding. We suggest that whenever possible, the 205mm long stem should be used if the biomechanical principles of the standard Exeter stem are to be utilised.

  9. Side-polished fiber based high sensitive temperature sensor

    NASA Astrophysics Data System (ADS)

    Prerana; Varshney, Ravi K.; Pal, Bishnu P.; Nagaraju, B.

    2010-12-01

    We present a high sensitive temperature sensor based on a side-polished fiber (SPF) coupled to a tapered multimode overlay waveguide (MMOW). We have theoretically shown that the longitudinal tapering of the MMOW can be used to tune the desired wavelength range in the spectrum without any loss in the sensitivity.

  10. A combined experimental and finite element approach to analyse the fretting mechanism of the head-stem taper junction in total hip replacement.

    PubMed

    Bitter, Thom; Khan, Imran; Marriott, Tim; Lovelady, Elaine; Verdonschot, Nico; Janssen, Dennis

    2017-09-01

    Fretting corrosion at the taper interface of modular hip implants has been implicated as a possible cause of implant failure. This study was set up to gain more insight in the taper mechanics that lead to fretting corrosion. The objectives of this study therefore were (1) to select experimental loading conditions to reproduce clinically relevant fretting corrosion features observed in retrieved components, (2) to develop a finite element model consistent with the fretting experiments and (3) to apply more complicated loading conditions of activities of daily living to the finite element model to study the taper mechanics. The experiments showed similar wear patterns on the taper surface as observed in retrievals. The finite element wear score based on Archard's law did not correlate well with the amount of material loss measured in the experiments. However, similar patterns were observed between the simulated micromotions and the experimental wear measurements. Although the finite element model could not be validated, the loading conditions based on activities of daily living demonstrate the importance of assembly load on the wear potential. These findings suggest that finite element models that do not incorporate geometry updates to account for wear loss may not be appropriate to predict wear volumes of taper connections.

  11. Experimental Measurement of the Static Coefficient of Friction at the Ti-Ti Taper Connection in Total Hip Arthroplasty.

    PubMed

    Bitter, T; Khan, I; Marriott, T; Schreurs, B W; Verdonschot, N; Janssen, D

    2016-03-01

    The modular taper junction in total hip replacements has been implicated as a possible source of wear. The finite-element (FE) method can be used to study the wear potential at the taper junction. For such simulations it is important to implement representative contact parameters, in order to achieve accurate results. One of the main parameters in FE simulations is the coefficient of friction. However, in current literature, there is quite a wide spread in coefficient of friction values (0.15 - 0.8), which has a significant effect on the outcome of the FE simulations. Therefore, to obtain more accurate results, one should use a coefficient of friction that is determined for the specific material couple being analyzed. In this study, the static coefficient of friction was determined for two types of titanium-on-titanium stem-adaptor couples, using actual cut-outs of the final implants, to ensure that the coefficient of friction was determined consistently for the actual implant material and surface finish characteristics. Two types of tapers were examined, Biomet type-1 and 12/14, where type-1 has a polished surface finish and the 12/14 is a microgrooved system. We found static coefficients of friction of 0.19 and 0.29 for the 12/14 and type-1 stem-adaptor couples, respectively.

  12. Parabolic tapers for overmoded waveguides

    DOEpatents

    Doane, J.L.

    1983-11-25

    A waveguide taper with a parabolic profile, in which the distance along the taper axis varies as the square of the tapered dimension, provides less mode conversion than equal length linear tapers and is easier to fabricate than other non-linear tapers.

  13. Compatible taper equation for loblolly pine

    Treesearch

    J. P. McClure; R. L. Czaplewski

    1986-01-01

    Cao's compatible, segmented polynomial taper equation (Q. V. Cao, H. E. Burkhart, and T. A. Max. For. Sci. 26: 71-80. 1980) is fitted to a large loblolly pine data set from the southeastern United States. Equations are presented that predict diameter at a given height, height to a given top diameter, and volume below a given position on the main stem. All...

  14. Taper Functions for Predicting Product Volumes in Natural Shortleaf Pines

    Treesearch

    Robert M. Farrar; Paul A. Murphy

    1987-01-01

    Taper (stem-profile) functions are presented for natural shortleaf pine (Pinus echinata Mill.) trees growing in the West Gulf area. These functions, when integrated, permit the prediction of volume between any two heights on a stem and, conversely by iteration, the volume between any two diameters on a stem. Examples are given of use of the functions...

  15. Tapered structure construction

    DOEpatents

    Smith, Eric D.; Takata, Rosalind K.; Slocum, Alexander H.; Nayfeh, Samir A.

    2016-04-05

    Feeding stock used to form a tapered structure into a curving device such that each point on the stock undergoes rotational motion about a peak location of the tapered structure; and the stock meets a predecessor portion of stock along one or more adjacent edges.

  16. Bone creep and short and long term subsidence after cemented stem total hip arthroplasty (THA).

    PubMed

    Norman, T L; Shultz, T; Noble, G; Gruen, T A; Blaha, J D

    2013-03-15

    Stem-cement and cement-bone interfacial failures as well as cement fractures have been noted in cemented total hip arthroplasty (THA) as the cause of aseptic loosening. Attempts to reduce the risk of femoral component loosening include improving the stem-cement interface by various coatings, using a textured or porous coated stem surfaces or by using a tapered stem having a highly-polished surface. The latter approach, often referred to as "force-closed" femoral stem design, would theoretically result in stem stabilization subsequent to debonding and 'taper-lock'. Previous work using three-dimensional finite element analysis has shown a state of stress at the stem-cement interface indicative of 'taper-lock' for the debonded stem and indicated that stem-cement interface friction and bone cement creep played a significant role in the magnitudes of stresses and subsidence of the stem. However, the previous analysis did not include the viscoelastic properties of bone, which has been hypothesized to permit additional expansion of the bone canal and allow additional stem subsidence (Lu and McKellop, 1997). The goal of this study was to investigate the effect of bone viscoelastic behavior on stem subsidence using a 3D finite element analysis. It was hypothesized that the viscoelastic behavior of bone in the hoop direction would allow expansion of the bone reducing the constraint on bone over time and permit additional stem subsidence, which may account for the discrepancies between predicted and clinical subsidence measurements. Analyses were conducted using physiological loads, 'average peak loads' and 'high peak loads' for 'normal patient' and 'active patient' (Bergmann et al., 2010) from which short and long term subsidence was predicted. Results indicated that bone creep does contribute to higher stem subsidence initially and after 10 years of simulated loading. However, it was concluded that the "constraint" upon the cement mantle is not mitigated enough to result in

  17. Defining stem profile model for wood valuation of red pine in Ontario and Michigan with consideration of stand density influence on tree taper

    Treesearch

    W. T. Zakrzewski; M. Penner; D. W. MacFarlane

    2007-01-01

    As part of the Canada-United States Great Lakes Stem Profile Modelling Project, established to support the local timber production process and to enable cross-border comparisons of timber volumes, here we present results of fitting Zakrzewski's (1999) stem profile model for red pine (Pinus resinosa Ait.) growing in Michigan, United States, and...

  18. Long-term results using the straight tapered femoral cementless hip stem in total hip arthroplasty: a minimum of twenty-year follow-up.

    PubMed

    Ateschrang, Atesch; Weise, Kuno; Weller, Siegfried; Stöckle, Ulrich; de Zwart, Peter; Ochs, Björn Gunnar

    2014-08-01

    We report the first long-term results of a prospective cohort study after total hip arthroplasty using the cementless Bicontact hip stem. Between 1987 and 1990, 250 total hip arthroplasties in 236 patients were performed using the cementless Bicontact hip stem. The average follow-up was 22.8 years (20.4-24.8) and average age at index surgery was 58.1 years. Eighty-one patients died and 9 were lost to follow-up. We noted 11 stem revisions revealing an overall Kaplan Meier survival rate of 95.0% (CI 95%: 91.1-97.2%). The average Harris Hip Score revealed 81 points (range 24-93). The Bicontact hip stem demonstrated high survival rates despite high ages and osteopenic changes, which are equivalent to other long-term reports of cementless stem fixation.

  19. Use of three-point taper systems in timber cruising

    Treesearch

    James W. Flewelling; Richard L. Ernst; Lawrence M. Raynes

    2000-01-01

    Tree volumes and profiles are often estimated as functions of total height and DBH. Alternative estimators include form-class methods, importance sampling, the centroid method, and multi-point profile (taper) estimation systems; all of these require some measurement or estimate of upper stem diameters. The multi-point profile system discussed here allows for upper stem...

  20. Tapered, tubular polyester fabric

    NASA Technical Reports Server (NTRS)

    Lapointe, Donat J. E. (Inventor); Wright, Lawrence T. (Inventor); Vincent, Laurence J. (Inventor)

    1987-01-01

    A tapered tubular polyester sleeve is described to serve as the flexible foundation for a spacesuit limb covering. The tube has a large end and a small end with a length to be determined. The ratio of taper is also determined by scale factors. All the warp yarns extend to the large end. A requisite number of warp yarns extend the full length of the sleeve. Other warp yarns extend from the large end but are terminated along the length of the sleeve. It is then woven with a filling yarn which extends in a full circle along the full length of the sleeve to thereby define the tapered sleeve. The sleeve after fabrication is then placed on a mandrel, heated in an oven, and then attached to the arm or other limb of the spacesuit.

  1. Tapered, tubular polyester fabric

    NASA Technical Reports Server (NTRS)

    LaPointe, Donat J. E. (Inventor); Vincent, Laurence J. (Inventor); Wright, Lawrence T. (Inventor)

    1988-01-01

    A tapered tubular polyester sleeve as set forth. It has a large end 12 and a small end 14 with a length to be determined. The ratio of taper is also determined by scale factors. All the warp yarns extend to the large end 12. A requisite number of warp yarns 16 extend the full length of the sleeve. Other warp yarns exemplified at 18, 22, 26, 28, 30 and 32 extend from the large end but are terminated along the length of the sleeve. It is then woven with a filling yarn 40 which extends in a full circle along the full length of the sleeve to thereby define the tapered sleeve. The sleeve after fabrication is then placed on a mandrel 42, heated in an oven 44 and is thereafter placed on the arm or other limb of a space suit exemplified at 50.

  2. Ultrasonic Polishing

    NASA Technical Reports Server (NTRS)

    Gilmore, Randy

    1993-01-01

    The ultrasonic polishing process makes use of the high-frequency (ultrasonic) vibrations of an abradable tool which automatically conforms to the work piece and an abrasive slurry to finish surfaces and edges on complex, highly detailed, close tolerance cavities in materials from beryllium copper to carbide. Applications range from critical deburring of guidance system components to removing EDM recast layers from aircraft engine components to polishing molds for forming carbide cutting tool inserts or injection molding plastics. A variety of materials including tool steels, carbides, and even ceramics can be successfully processed. Since the abradable tool automatically conforms to the work piece geometry, the ultrasonic finishing method described offers a number of important benefits in finishing components with complex geometries.

  3. Taper of wood poles

    Treesearch

    Billy Bohannan; Hermann Habermann; Joan E. Lengel

    1974-01-01

    Round wood pole use has changed without accompanying advancement in engineering design data. Previous pole design was based on the assumption that maximum stress occurred at the groundline but, with the larger poles that are now being used, maximum stress may occur along the pole length. For accurate engineering analysis the shape or taper of a pole must be known. Both...

  4. Compound taper milling machine

    NASA Technical Reports Server (NTRS)

    Campbell, N. R.

    1969-01-01

    Simple, inexpensive milling machine tapers panels from a common apex to a uniform height at panel edge regardless of the panel perimeter configuration. The machine consists of an adjustable angled beam upon which the milling tool moves back and forth above a rotatable table upon which the workpiece is held.

  5. The Influence of Contamination and Cleaning on the Strength of Modular Head Taper Fixation in Total Hip Arthroplasty.

    PubMed

    Krull, Annika; Morlock, Michael M; Bishop, Nicholas E

    2017-05-13

    Intraoperative interface contamination of modular head-stem taper junctions of hip implants can lead to poor fixation strength, causing fretting and crevice corrosion or even stem taper fracture. Careful cleaning before assembly should help to reduce these problems. The purpose of this study was to determine the effect of cleaning (with and without drying) contaminated taper interfaces on the taper fixation strength. Metal or ceramic heads were impacted onto titanium alloy stem tapers with cleaned or contaminated (fat or saline solution) interfaces. The same procedure was performed after cleaning and drying the contaminated interfaces. Pull-off force was used to determine the influence of contamination and cleaning on the taper strength. Pull-off forces after contamination with fat were significantly lower than those for uncontaminated interfaces for both head materials. Pull-off forces after application of saline solution were not significantly different from those for uncontaminated tapers. However, a large variation in taper strength was observed, pull-off forces for cleaned and dried tapers were similar to those for uncontaminated tapers for both head materials. Intraoperative contamination of taper interfaces may be difficult to detect but has a major influence on taper fixation strength. Cleaning of the stem taper with saline solution and drying with gauze directly before assembly allows the taper strength of the pristine components to be achieved. Not drying the taper results in a large variation in pull-off forces, emphasizing that drying is essential for sufficient and reproducible fixation strength. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Does Surface Topography Play a Role in Taper Damage in Head-neck Modular Junctions?

    PubMed

    Pourzal, Robin; Hall, Deborah J; Ha, Nguyen Q; Urban, Robert M; Levine, Brett R; Jacobs, Joshua J; Lundberg, Hannah J

    2016-10-01

    There are increasing reports of total hip arthroplasty failure subsequent to modular taper junction corrosion. The surfaces of tapers are machined to have circumferential machining marks, resulting in a surface topography of alternating peaks and valleys on the scale of micrometers. It is unclear if the geometry of this machined surface topography influences the degree of fretting and corrosion damage present on modular taper junctions or if there are differences between modular taper junction material couples. (1) What are the differences in damage score and surface topography between CoCr/CoCr and CoCr/Ti modular junctions? (2) How are initial surface topography, flexural rigidity, taper angle mismatch, and time in situ related to visual taper damage scores for CoCr/CoCr couples? (3) How are initial surface topography, flexural rigidity, taper angle mismatch, and time in situ related to visual taper damage scores for CoCr/Ti couples? Damage on stem and head tapers was evaluated with a modified Goldberg score. Differences in damage scores were determined between a group of 140 CoCr/CoCr couples and 129 CoCr/Ti couples using a chi-square test. For a subgroup of 70 retrievals, selected at random, we measured five variables, including initial stem taper machining mark height and spacing, initial head taper roughness, flexural rigidity, and taper angle mismatch. All retrievals were obtained at revision surgeries. None were retrieved as a result of metal-on-metal failures or were recalled implants. Components were chosen so there was a comparable number of each material couple and damage score. Machining marks around the circumference of the tapers were measured using white light interferometry to characterize the initial stem taper surface topography in terms of the height of and spacing between machining mark peaks as well as initial head taper roughness. The taper angle mismatch was assessed with a coordinate measuring machine. Flexural rigidity was determined based

  7. Good stability but high periprosthetic bone mineral loss and late-occurring periprosthetic fractures with use of uncemented tapered femoral stems in patients with a femoral neck fracture

    PubMed Central

    Sjöö, Helene; Kelly-Pettersson, Paula; Bodén, Henrik; Eisler, Thomas; Stark, André; Muren, Olle

    2014-01-01

    Background and purpose We previously evaluated a new uncemented femoral stem designed for elderly patients with a femoral neck fracture and found stable implant fixation and good clinical results up to 2 years postoperatively, despite substantial periprosthetic bone mineral loss. We now present the medium-term follow-up results from this study. Patients and methods In this observational prospective cohort study, we included 50 patients (mean age 81 (70–92) years) with a femoral neck fracture. All patients underwent surgery with a cemented cup and an uncemented stem specifically designed for fracture treatment. Outcome variables were migration of the stem measured with radiostereometry (RSA) and periprosthetic change in bone mineral density (BMD), measured with dual-energy X-ray absorptiometry (DXA). Hip function and health-related quality of life were assessed using the Harris hip score (HHS) and the EuroQol-5D (EQ-5D). DXA and RSA data were collected at regular intervals up to 4 years, and data concerning reoperations and hip-related complications were collected during a mean follow-up time of 5 (0.2–7.5) years. Results At 5 years, 19 patients had either passed away or were unavailable for further participation and 31 could be followed up. Of the original 50 patients, 6 patients had suffered a periprosthetic fracture, all of them sustained after the 2-year follow-up. In 19 patients, we obtained complete RSA and DXA data and no component had migrated after the 2-year follow-up. We also found a continuous total periprosthetic bone loss amounting to a median of –19% (–39 to 2). No changes in HHS or EQ-5D were observed during the follow-up period. Interpretation In this medium-term follow-up, the stem remained firmly fixed in bone despite considerable periprosthetic bone mineral loss. However, this bone loss might explain the high number of late-occurring periprosthetic fractures. Based on these results, we would not recommend uncemented femoral stems for the

  8. Tapered capillary optics

    DOEpatents

    Hirsch, Gregory

    1998-01-01

    A metal or glass wire is etched with great precision into a very narrowly tapering cone which has the shape of the desired final capillary-optics bore. By controlling the rate of removal of the wire from an etchant bath, a carefully controlled taper is produced. A sensor measures the diameter of the wire as it leaves the surface of the etchant. This signal is used for feedback control of the withdrawal speed. The etched wire undergoes a treatment to produce an extremely low surface-roughness. The etched and smoothed wire is coated with the material of choice for optimizing the reflectivity of the radiation being focused. This could be a vacuum evaporation, sputtering, CVD or aqueous chemical process. The coated wire is either electroplated, built up with electroless plating, or encapsulated in a polymer cylinder such as epoxy to increase the diameter of the wire for easier handling and greater robustness. During this process, the wire is vertically oriented and tensioned to assure that the wire is absolutely straight. The coated and electroformed wire is bonded to a flat, rigid substrate and is then periodically segmented by cutting or etching a series of narrow slits or grooves into the wire. The wire is vertically oriented and tensioned during the bonding process to assure that it is straight. The original wire material is then chemically etched away through the slits or otherwise withdrawn to leave the hollow internal bore of the final tapered-capillary optical element.

  9. Endfire tapered slot antenna characteristics

    NASA Technical Reports Server (NTRS)

    Schaubert, D. H.

    1989-01-01

    Typical configurations and operating characteristics for endfire tapered slot antennas are described. The feed transition modeling and moment method modeling techniques are utilized to predict antenna performance. The radiation pattern and cross polarization properties for the linearly tapered slot antennas are examined. Endfire tapered slot antennas are applicable for wide-band scanning arrays and focal plane arrays for imaging and multiple beam reflector systems.

  10. Tapered-Fin Thermal Interfaces

    NASA Technical Reports Server (NTRS)

    Poulin, Elizabeth C.

    1992-01-01

    Two meshing sets of tapered fins used as thermal interface with relatively low clamping forces. When in contact, fins provide large area for transfer of heat. Taper ensures easy mating and demating of fins and transfers clamping force to surfaces in contact; improving contact and transfer of heat. Fins arranged in rows, concentric rings, or other configurations.

  11. TAPERED DEFINING SLOT

    DOEpatents

    Pressey, F.W.

    1959-09-01

    An improvement is reported in the shape and formation of the slot or opening in the collimating slot member which forms part of an ion source of the type wherein a vapor of the material to be ionized is bombarded by electrons in a magnetic field to strike an arc-producing ionization. The defining slot is formed so as to have a substantial taper away from the cathode, causing the electron bombardment from the cathode to be dispersed over a greater area reducing its temperature and at the same time bringing the principal concentration of heat from the electron bombardment nearer the anode side of the slot, thus reducing deterioration and prolonging the life of the slot member during operation.

  12. Artificial Intelligence Procedures for Tree Taper Estimation within a Complex Vegetation Mosaic in Brazil.

    PubMed

    Nunes, Matheus Henrique; Görgens, Eric Bastos

    2016-01-01

    Tree stem form in native tropical forests is very irregular, posing a challenge to establishing taper equations that can accurately predict the diameter at any height along the stem and subsequently merchantable volume. Artificial intelligence approaches can be useful techniques in minimizing estimation errors within complex variations of vegetation. We evaluated the performance of Random Forest® regression tree and Artificial Neural Network procedures in modelling stem taper. Diameters and volume outside bark were compared to a traditional taper-based equation across a tropical Brazilian savanna, a seasonal semi-deciduous forest and a rainforest. Neural network models were found to be more accurate than the traditional taper equation. Random forest showed trends in the residuals from the diameter prediction and provided the least precise and accurate estimations for all forest types. This study provides insights into the superiority of a neural network, which provided advantages regarding the handling of local effects.

  13. Artificial Intelligence Procedures for Tree Taper Estimation within a Complex Vegetation Mosaic in Brazil

    PubMed Central

    Nunes, Matheus Henrique

    2016-01-01

    Tree stem form in native tropical forests is very irregular, posing a challenge to establishing taper equations that can accurately predict the diameter at any height along the stem and subsequently merchantable volume. Artificial intelligence approaches can be useful techniques in minimizing estimation errors within complex variations of vegetation. We evaluated the performance of Random Forest® regression tree and Artificial Neural Network procedures in modelling stem taper. Diameters and volume outside bark were compared to a traditional taper-based equation across a tropical Brazilian savanna, a seasonal semi-deciduous forest and a rainforest. Neural network models were found to be more accurate than the traditional taper equation. Random forest showed trends in the residuals from the diameter prediction and provided the least precise and accurate estimations for all forest types. This study provides insights into the superiority of a neural network, which provided advantages regarding the handling of local effects. PMID:27187074

  14. Tapered undulator for SASE FELs

    SciTech Connect

    Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je; Vinokurov, Nikolai A.

    2001-09-14

    We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission (SASE), where the radiation tends to have a relatively broad bandwidth, limited temporal phase coherence, and large amplitude fluctuations. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of a tapered undulator for parameters corresponding to the existing Argonne low-energy undulator test line (LEUTL) FEL. We also study possible tapering options for proposed x-ray FELs such as the Linac Coherent Light Source (LCLS).

  15. Williamson Polishing & Plating Site

    EPA Pesticide Factsheets

    Williamson Polishing & Plating Co. Inc. was a plating shop located in the Martindale-Brightwood neighborhood of Indianapolis. The facility conducted job shop polishing and electroplating services. The vacant site contains a 14,651-square-foot building.

  16. Head-Neck Taper Corrosion in Hip Arthroplasty

    PubMed Central

    Hussenbocus, S.; Kosuge, D.; Solomon, L. B.; Howie, D. W.; Oskouei, R. H.

    2015-01-01

    Modularity at the head-neck junction of the femoral component in THA became popular as a design feature with advantages of decreasing implant inventory and allowing adjustment of leg length, offset, and soft tissue balancing through different head options. The introduction of a new modular interface to femoral stems that were previously monoblock, or nonmodular, comes with the potential for corrosion at the taper junction through mechanically assisted crevice corrosion. The incidence of revision hip arthroplasty is on the rise and along with improved wear properties of polyethylene and ceramic, use of larger femoral head sizes is becoming increasingly popular. Taper corrosion appears to be related to all of its geometric parameters, material combinations, and femoral head size. This review article discusses the pathogenesis, risk factors, clinical assessment, and management of taper corrosion at the head-neck junction. PMID:25954757

  17. Tapered undulators for SASE FELs

    NASA Astrophysics Data System (ADS)

    Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je; Vinokurov, Nikolai A.

    2002-05-01

    We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission, where the radiation tends to have a relatively broad bandwidth and limited temporal coherence. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of tapered undulators for parameters corresponding to the Argonne low-energy undulator test line FEL and the proposed linac coherent light source.

  18. Effect of trunnion roughness and length on the modular taper junction strength under typical intraoperative assembly forces.

    PubMed

    Jauch-Matt, S Y; Miles, A W; Gill, H S

    2017-01-01

    Modular hip implants are at risk of fretting-induced postoperative complications most likely initiated by micromotion between adjacent implant components. A stable fixation between ball head and stem-neck taper is critical to avoid excessive interface motions. Therefore, the aim of this study was to identify the effect of trunnion roughness and length on the modular taper strength under typical intraoperative assembly forces. Custom-made Titanium trunnions (standard/mini taper, smooth/grooved surface finish) were assembled with modular Cobalt-chromium heads by impaction with peak forces ranging from 2kN to 6kN. After each assembly process these were disassembled with a materials testing machine to detect the pull-off force as a measure for the taper strength. As expected, the pull-off forces increased with rising peak assembly force (p < 0.001). For low and moderate assembly forces, smooth standard tapers offered higher pull-off forces compared to grooved tapers (p < 0.038). In the case of an assembly force of 2kN, mini tapers showed a higher taper strength than standard ones (p=0.037). The results of this study showed that smooth tapers provided a higher strength for taper junctions. This higher taper strength may reduce the risk of fretting-related complications especially in the most common range of intraoperative assembly forces.

  19. Biomass and Taper for Trees in Thinned and Unthinned Longleaf Pine Plantations

    Treesearch

    Charles E. Thomas; Bernard R. Parresol; Kim H. N. Le; Richard E. Lohrey

    1995-01-01

    Longleafpine (Pinus palustris Mill.) trees growing in thinned plantation studies in Louisiana and Texas and unthinned stands from the Louisiana sites were sampled for establishing taper, volume, and specific gravity. Stem analysis data were collected on 147 stems ranging in age from 30 to 50 yr. Analyses of covariance (ANCOVAs) were employed to...

  20. Segmented polynomial taper equation incorporating years since thinning for loblolly pine plantations

    Treesearch

    A. Gordon Holley; Thomas B. Lynch; Charles T. Stiff; William Stansfield

    2010-01-01

    Data from 108 trees felled from 16 loblolly pine stands owned by Temple-Inland Forest Products Corp. were used to determine effects of years since thinning (YST) on stem taper using the Max–Burkhart type segmented polynomial taper model. Sample tree YST ranged from two to nine years prior to destructive sampling. In an effort to equalize sample sizes, tree data were...

  1. EPRI condensate polisher guidelines

    SciTech Connect

    Larkin, B.A.; Webb, L.C.; Sawochka, S.G.; Crits, G.J.; Pocock, F.J.; Wirth, L.

    1995-01-01

    Cycle chemistry is one of the most important contributors to the loss of availability of generating units. Condensate polishing can significantly improve cycle chemistry by improving cycle water quality and minimizing the transport of contaminants in the power cycle. The EPRI-funded project described in this paper developed comprehensive guidelines for condensate polishing based upon information gathered from utility surveys, equipment vendors, and resin suppliers. Existing literature was also surveyed for pertinent input. Comprehensive guidelines which outline guidance for design, operation, maintenance, surveillance, management, and retrofitting of condensate polishing systems were developed. Economics of condensate polishing were evaluated and a roadmap for economic evaluation for utilities to follow was produced.

  2. Ceramic Heads Decrease Metal Release Caused by Head-taper Fretting and Corrosion.

    PubMed

    Kocagoz, Sevi B; Underwood, Richard J; MacDonald, Daniel W; Gilbert, Jeremy L; Kurtz, Steven M

    2016-04-01

    Metal release resulting from taper fretting and corrosion is a clinical concern, because wear and corrosion products may stimulate adverse local tissue reactions. Unimodular hip arthroplasties have a conical taper between the femoral head (head bore taper) and the femoral stem (stem cone taper). The use of ceramic heads has been suggested as a way of reducing the generation of wear and corrosion products from the head bore/stem cone taper junction. A previous semiquantitative study found that ceramic heads had less visual evidence of fretting-corrosion damage compared with CoCr heads; but, to our knowledge, no studies have quantified the volumetric material loss from the head bore and stem cone tapers of a matched cohort of ceramic and metal heads. We asked: (1) Do ceramic heads result in less volume of material loss at the head-stem junction compared with CoCr heads; (2) do stem cone tapers have less volumetric material loss compared with CoCr head bore tapers; (3) do visual fretting-corrosion scores correlate with volumetric material loss; and (4) are device, patient, or intraoperative factors associated with volumetric material loss? A quantitative method was developed to estimate volumetric material loss from the head and stem taper in previously matched cohorts of 50 ceramic and 50 CoCr head-stem pairs retrieved during revision surgery for causes not related to adverse reactions to metal particles. The cohorts were matched according to (1) implantation time, (2) stem flexural rigidity, and (3) lateral offset. Fretting corrosion was assessed visually using a previously published four-point, semiquantitative scoring system. The volumetric loss was measured using a precision roundness machine. Using 24 equally spaced axial traces, the volumetric loss was estimated using a linear least squares fit to interpolate the as-manufactured surfaces. The results of this analysis were considered in the context of device (taper angle clearance, head size, head offset

  3. Tapered optical fibres for sensing

    NASA Astrophysics Data System (ADS)

    Martan, Tomas; Kanka, Jiri; Kasik, Ivan; Matejec, Vlastimil

    2008-11-01

    Recently, optical fibre tapers have intensively been investigated for many applications e.g. in telecommunications, medicine and (bio-) chemical sensing. The paper deals with enhancement of evanescent-field sensitivity of the solid-core microstructured fibre with steering-wheel air-cladding. Enhancement of a performance of the microstructured fibre is based on reduction of fibre core diameter down to narrow filament by tapering thereby defined part of light power is guided by an evanescent wave traveling in axial cladding air holes. The original fibre structure with outer diameter of 125 µm was reduced 2×, 2.5×, 3.33×, and 4× for increasing relatively small intensity overlap of guided core mode at wavelength of 1.55 μm with axial air holes. The inner structures of tapered microstructured fibre with steering-wheel aircladding were numerically analyzed and mode intensity distributions were calculated using the FDTD technique. Analyzed fiber tapers were prepared by constructed fibre puller employing 'flame brush technique'.

  4. Taper tables for western hemlock.

    Treesearch

    Floyd A. Johnson; Wilbur. Engstrom

    1949-01-01

    In 1947 the West Coast Forestry procedures Committee recommended several mensuration projects, one of which called for the construction of taper tables for Western hemlock. In response the present tables were prepared. Basic data for these tables consist of measurements of 912 trees taken a number of years ago by members of the Pacific Northwest Forest & Range...

  5. Polish Literature in Exile.

    ERIC Educational Resources Information Center

    Zielinska, Marie F.

    1994-01-01

    Presents a brief historical overview of the development of Polish literature in exile with emphasis on publishing. The upheaval of World War II left many Poles outside their native land. They have created a flourishing press and literature, with 21 Polish houses outside of Poland and other active presses. (SLD)

  6. Communicating in Polish.

    ERIC Educational Resources Information Center

    Penny, Bernard; Malinowska, Krystyna T.

    This Polish textbook consists of a series of narrations and dialogs based on photographs depicting typical activities in the daily lives of Polish citizens. Two sets of questions follow each selection; the first set is intended to stimulate communication on what has been seen and heard, while the second set asks the students to compare what they…

  7. Tapered laser rods as a means of minimizing the path length of trapped barrel mode rays

    DOEpatents

    Beach, Raymond J.; Honea, Eric C.; Payne, Stephen A.; Mercer, Ian; Perry, Michael D.

    2005-08-30

    By tapering the diameter of a flanged barrel laser rod over its length, the maximum trapped path length of a barrel mode can be dramatically reduced, thereby reducing the ability of the trapped spontaneous emission to negatively impact laser performance through amplified spontaneous emission (ASE). Laser rods with polished barrels and flanged end caps have found increasing application in diode array end-pumped laser systems. The polished barrel of the rod serves to confine diode array pump light within the rod. In systems utilizing an end-pumping geometry and such polished barrel laser rods, the pump light that is introduced into one or both ends of the laser rod, is ducted down the length of the rod via the total internal reflections (TIRs) that occur when the light strikes the rod's barrel. A disadvantage of using polished barrel laser rods is that such rods are very susceptible to barrel mode paths that can trap spontaneous emission over long path lengths. This trapped spontaneous emission can then be amplified through stimulated emission resulting in a situation where the stored energy available to the desired lasing mode is effectively depleted, which then negatively impacts the laser's performance, a result that is effectively reduced by introducing a taper onto the laser rod.

  8. Rediscovery of Polish meteorites

    NASA Astrophysics Data System (ADS)

    Tymiński, Z.; Stolarz, M.; Żołądek, P.; Wiśniewski, M.; Olech, A.

    2016-01-01

    The total number of Polish registered meteorites (by July 2016) including the meteoritical artifacts as Czestochowa Raków I and II is 22. Most of them are described by the pioneer of Polish Meteoritics Jerzy Pokrzywnicki who also identified the meteorite fall locations. In recent years prospectors found impressive specimens of known Polish meteorites such as Morasko: 34 kg, 50 kg, 164 kg, 174 kg and 261 kg or Pultusk: 1578 g, 1576 g, 1510 g, 610 g and 580 g expanding and determining precisely the known meteorite strewn fields.

  9. Thread gauge for tapered threads

    DOEpatents

    Brewster, A.L.

    1994-01-11

    The thread gauge permits the user to determine the pitch diameter of tapered threads at the intersection of the pitch cone and the end face of the object being measured. A pair of opposed anvils having lines of threads which match the configuration and taper of the threads on the part being measured are brought into meshing engagement with the threads on opposite sides of the part. The anvils are located linearly into their proper positions by stop fingers on the anvils that are brought into abutting engagement with the end face of the part. This places predetermined reference points of the pitch cone of the thread anvils in registration with corresponding points on the end face of the part being measured, resulting in an accurate determination of the pitch diameter at that location. The thread anvils can be arranged for measuring either internal or external threads. 13 figures.

  10. Thread gauge for tapered threads

    DOEpatents

    Brewster, Albert L.

    1994-01-11

    The thread gauge permits the user to determine the pitch diameter of tapered threads at the intersection of the pitch cone and the end face of the object being measured. A pair of opposed anvils having lines of threads which match the configuration and taper of the threads on the part being measured are brought into meshing engagement with the threads on opposite sides of the part. The anvils are located linearly into their proper positions by stop fingers on the anvils that are brought into abutting engagement with the end face of the part. This places predetermined reference points of the pitch cone of the thread anvils in registration with corresponding points on the end face of the part being measured, resulting in an accurate determination of the pitch diameter at that location. The thread anvils can be arranged for measuring either internal or external threads.

  11. Fracture of the C-Stem cemented femoral component in revision hip surgery using bone impaction grafting technique: report of 9 cases.

    PubMed

    Buttaro, Martin; Comba, Fernando; Zanotti, Gerardo; Piccaluga, Francisco

    2015-01-01

    We present a series of 9 fractures of a C-Stem femoral component (6 long stems and 3 conventional stems) that had been implanted with the use of impaction bone grafting (IBG). The length of the long fractured stems was 240 mm in 4 cases and 200 mm in 2. The patients presented had an average BMI of 26.5 and an average of 2.7 previous hip surgeries (range 2-5 surgeries) before the stem fracture. A total of 5 cases presented with a metal mesh fracture in addition to the fractured stem. Bending of the stems or stem defects was not observed in any case. Typical fracture waves consistent with fatigue failure were clearly visible on all the cut surfaces, starting anterolaterally and propagating to the medial side. Although fatigue fracture of a modern cemented tapered polished femoral stem is a rare event, stress due to the absence of proximal femoral bone support could be sufficient to put this stem at a higher risk for fatigue fracture in non-obese patients.

  12. Polished polymide substrate

    DOEpatents

    Farah, John; Sudarshanam, Venkatapuram S.

    2003-05-13

    Polymer substrates, in particular polyimide substrates, and polymer laminates for optical applications are described. Polyimide substrates are polished on one or both sides depending on their thickness, and single-layer or multi-layer waveguide structures are deposited on the polished polyimide substrates. Optical waveguide devices are machined by laser ablation using a combination of IR and UV lasers. A waveguide-fiber coupler with a laser-machined groove for retaining the fiber is also disclosed.

  13. Buprenorphine tapering schedule and illicit opioid use

    PubMed Central

    Ling, Walter; Hillhouse, Maureen; Domier, Catherine; Doraimani, Geetha; Hunter, Jeremy; Thomas, Christie; Jenkins, Jessica; Hasson, Albert; Annon, Jeffrey; Saxon, Andrew; Selzer, Jeffrey; Boverman, Joshua; Bilangi, Richard

    2011-01-01

    Aims To compare the effects of a short or long taper schedule after buprenorphine stabilization on participant outcomes as measured by opioid-free urine tests at the end of each taper period. Design This multi-site study sponsored by Clinical Trials Network (CTN, a branch of the US National Institute on Drug Abuse) was conducted from 2003 to 2005 to compare two taper conditions (7 days and 28 days). Data were collected at weekly clinic visits to the end of the taper periods, and at 1-month and 3-month post-taper follow-up visits. Setting Eleven out-patient treatment programs in 10 US cities. Intervention Non-blinded dosing with Suboxone® during the 1-month stabilization phase included 3 weeks of flexible dosing as determined appropriate by the study physicians. A fixed dose was required for the final week before beginning the taper phase. Measurements The percentage of participants in each taper group providing urine samples free of illicit opioids at the end of the taper and at follow-up. Findings At the end of the taper, 44% of the 7-day taper group (n = 255) provided opioid-free urine specimens compared to 30% of the 28-day taper group (n = 261; P = 0.0007). There were no differences at the 1-month and 3-month follow-ups (7-day = 18% and 12%; 28-day = 18% and 13%, 1 month and 3 months, respectively). Conclusion For individuals terminating buprenorphine pharmacotherapy for opioid dependence, there appears to be no advantage in prolonging the duration of taper. PMID:19149822

  14. Theory and Simulations of Tapered Diblock Polymers

    NASA Astrophysics Data System (ADS)

    Hall, Lisa M.; Seo, Youngmi; Brown, Jonathan R.

    We study tapered block polymers, AB diblock polymers with a gradient region inserted between the pure A and B blocks such that composition smoothly transitions from A to B (or B to A in the case of inverse tapers). Phase diagrams were created using self consistent field theory (SCFT), and coarse-grained molecular dynamics (MD) simulations were used to study polymer conformations and diffusion, including diffusion of monomer-sized penetrants preferentially dissolved in one of the phases. As has been observed experimentally, we find that tapering makes the A and B blocks more miscible, decreasing domain spacing and shifting the order to disorder transition to lower temperatures. We predict a widening of the bicontinuous double gyroid region of the phase diagram for moderate length normal tapers versus diblocks, suggesting taper length can be used as a control parameter to obtain network phases even at high molecular weight, as may be desirable in transport applications. Additionally, in some inverse tapered systems, SCFT predicts phases not present in the standard AB diblock phase diagram, and MD simulations show how the chains fold back and forth across the interface. In these inverse tapered polymers, as segregation strength is increased, the competing effects of folding and stretching produces lamellae that have domain spacing nearly independent of temperature. We also find that diffusion of penetrants in normal tapers is significantly faster than that in inverse tapers, which is likely related to their unusual conformations. This material is based upon work supported by DOE Grant SC0014209.

  15. Identification of the class characteristics in the handwriting of Polish people writing in English.

    PubMed

    Turnbull, Susan J; Jones, Allison E; Allen, Mike

    2010-09-01

    An investigation was carried out to identify the class characteristics of Polish people writing in English and to specifically identify those characteristics that separate Polish handwriting from English handwriting. In the first stage, 40 Polish and 40 English handwriting samples were collected and systematically examined. In total, 31 features were identified that occurred in ≥25% of the Polish handwriting samples and therefore considered class characteristics. Of these, chi-square analyses identified 21 class characteristics that occurred significantly more in Polish compared to English handwriting. Twenty-one of the class characteristics in the Polish handwriting had similar constructions to the copybook pattern thus supporting the theory that class characteristics frequently stem from the taught writing system. In the second stage, an algorithm was developed using seventeen of the class characteristics that successfully discriminated between a further 13 Polish and 12 English handwriting samples.

  16. Taper equation and volume tables for plantation-grown red alder.

    Treesearch

    Andrew A. Bluhm; Sean M. Garber; David E. Hibbs

    2007-01-01

    A taper equation and associated tables are presented for red alder (Alnus rubra Bong.) trees grown in plantations. The data were gathered from variable-density experimental plantations throughout the Pacific Northwest. Diameter inside bark along the stem was fitted to a variable exponent model form by using generalized nonlinear least squares and a...

  17. Analysis of the polishing slurry flow of chemical mechanical polishing by polishing pad with phyllotactic pattern

    NASA Astrophysics Data System (ADS)

    Lv, Yushan; Zhang, Tian; Wang, Jun; Li, Nan; Duan, Min; Xing, Xue-Ling

    2010-12-01

    In order to make the polishing slurry distribution more uniform over the polishing region, a new kind of polishing pad, which has sunflower seed pattern, has been designed based on the phyllotaxis theory of biology, and the boundary conditions of polishing slurry flow have been established. By the help of computational fluid dynamics software (FLUENT), the flow state of the polishing slurry is simulated and the effects of the phyllotactic parameters of polishing pad on the flow field of polishing slurry are analyzed. The results show that when the polishing slurry is imported from the center of phyllotaxis polishing pad, the slurry flows along the counterclockwise and clockwise spiral grooves of phyllotatic pattern, which make fluid flow divergence around, and the flow field becomes more uniform.

  18. [Activity Polish Physicians of Transcarpathian].

    PubMed

    Ar, Pułyk

    2015-01-01

    The article presents the history of founding of the Organisation of Polish Physicians of Transcarpathian and their participation in presentation of the achievements of Polish Medical Sciences in Ukraine.

  19. Circular tapered tape fabrication: Final report

    SciTech Connect

    Stockdale, D.A.

    1988-04-01

    A new approach to producing tapered tapes has been developed involving generating a tapered tape in a circular configuration on a lathe rather than a mill. This approach is more cost-effective and the redesigned slot configuration induced less stress on the tapes during installation and removal.

  20. Measurement and optimization of the light collection uniformity in strongly tapered PWO crystals of the PANDA detector

    NASA Astrophysics Data System (ADS)

    Diehl, Stefan; Bremer, Daniel; Brinkmann, Kai-Thomas; Dormenev, Valery; Eissner, Tobias; Novotny, Rainer W.; Rosenbaum, Christoph; Zaunick, Hans-Georg

    2017-06-01

    The uniformity of the light collection is a crucial parameter for detectors based on inorganic scintillation crystals to guarantee a response proportional to the deposited energy. Especially in case of tapered crystals, like they are widely used to realize a 4π geometry of electromagnetic calorimeters (EMC) in high energy physics experiments, a strong non-uniformity is introduced by an additional focusing of the scintillation light due to the tapered geometry. The paper will discuss the determination and the reduction of the non-uniformity in strongly tapered lead tungstate crystals as used for the construction of the electromagnetic calorimeter of the PANDA detector at the future Facility for Antiproton and Ion Research (FAIR). Among different concepts for an uniformization a single de-polished lateral side face provided the optimum result with a remaining non-uniformity below 5% in good agreement with similar studies for the CMS ECAL at LHC. The impact on the achievable energy resolution in the energy regime of photons below 800 MeV is discussed in detail in comparison to GEANT4 simulations. The comparison of the response of two arrays with polished and de-polished crystals, respectively, shows in the latter case a significant improvement of the constant term of the parametrization of the energy resolution down to 0.5% accompanied by only very slight increase of the statistical term.

  1. Polish Higher Education: Intersectoral Distinctiveness

    ERIC Educational Resources Information Center

    Musial, Joanna

    2014-01-01

    This study analyzes degrees of differences between the private and public sectors of Polish higher education. It finds them to be strong: Polish private institutions function very differently from Polish public institutions and these differences correspond with those found in the literature on higher education elsewhere in the world. Polish…

  2. [Polish nomenclature of lumbar disc disease].

    PubMed

    Radło, Paweł; Smetkowski, Andrzej; Tesiorowski, Maciej

    2014-01-01

    Lumbar disc herniation is one of the most common damage of musculoskeletal system. The incidence of pain of lumbosacral spine is estimated approximately on 60-90% in general population, whereas the incidence of disc herniation in patients experiencing low back pain is about 91%. Despite the high incidence and uncomplicated pathogenesis of disc disease there is a problem with the nomenclature. In the vast majority of cases, the naming confusion stems from ignorance of the etiology of low back pain. Different terminologies: morphological, topographical, Radiological and Clinical are used interchangeably. In addition, diagnosis is presented in a variety of languages: Polish, English and Latin. Moreover, the medical and traditional language are used alternately. The authors found in Polish literature more, than 20 terms to describe lumbar disc herniation. All of these terms in the meaning of the authors are used to determine one pathology--mechanical damage to the intervertebral disc and moving the disc material beyond the anatomical area.

  3. Know Your Laws. Polish.

    ERIC Educational Resources Information Center

    Watson, Joan Q.; Kopania, Margaret

    This Polish language version of "Know Your Laws" consists of 24 self-contained modules designed to acquaint the Florida adult student with laws she/he will meet in everyday life; fundamentals of local, state, and federal governments; and the criminal and juvenile justice systems. (The 130 objectives are categorized in the first three…

  4. Know Your Laws. Polish.

    ERIC Educational Resources Information Center

    Watson, Joan Q.; Kopania, Margaret

    This Polish language version of "Know Your Laws" consists of 24 self-contained modules designed to acquaint the Florida adult student with laws she/he will meet in everyday life; fundamentals of local, state, and federal governments; and the criminal and juvenile justice systems. (The 130 objectives are categorized in the first three…

  5. Frequency coded sensors incorporating tapers

    NASA Technical Reports Server (NTRS)

    Hines, Jacqueline H. (Inventor); Solie, Leland P. (Inventor)

    2010-01-01

    A surface acoustic wave device includes a piezoelectric substrate on which is formed a transducer that generates acoustic waves on the surface of the substrate from electrical waves received by the transducer. The waves are carried along an acoustic track to either a second transducer or a reflector. The transducers or transducer and reflector are formed of subsections that are constructed to operate at mutually different frequencies. The subsections of at least one of the transducers or transducer and reflector are out of alignment with respect to one another relative to the transverse of the propagation direction. The out of aligned subsections provide not only a frequency component but also a time to the signal output signal. Frequency response characteristics are improved. An alternative embodiment provides that the transducers and/or reflectors are continuously tapered instead of having discrete frequency subsections.

  6. STEM?!?!

    ERIC Educational Resources Information Center

    Merrill, Jen

    2012-01-01

    The author's son has been an engineer since birth. He never asked "why" as a toddler, it was always "how's it work?" So that he wanted a STEM-based home education was no big surprise. In this article, the author considers what kind of curricula would work best for her complex kid.

  7. STEM?!?!

    ERIC Educational Resources Information Center

    Merrill, Jen

    2012-01-01

    The author's son has been an engineer since birth. He never asked "why" as a toddler, it was always "how's it work?" So that he wanted a STEM-based home education was no big surprise. In this article, the author considers what kind of curricula would work best for her complex kid.

  8. Nonlinear optics in tapered silicon fibres

    NASA Astrophysics Data System (ADS)

    Peacock, Anna C.; Healy, Noel

    2012-06-01

    Tapered fibres provide a unique means to manipulate pulse propagation for use in all-optical signal processing applications. Recently, we have demonstrated a new class of taper that is fabricated from our silicon core optical fibre platform. Owing to the high core-cladding index contrast, these silicon tapered fibres can accommodate large taper ratios over short millimetre lengths without introducing any appreciable loss. Such strong tapers allow for unprecedented control over the dispersion and nonlinearity parameters for the tailoring of femtosecond pulse propagation. Using numerical simulations based on realistic tapered fibres with micro to nanoscale core dimensions, we have shown that it is possible to exploit the longitudinally varying waveguide parameters for nonlinear pulse shaping in both the normal and anomalous dispersion regimes. In the normal dispersion regime, we have made use of a decreasing dispersion profile to generate linearly chirped parabolic pulses which allow for high power distortion-free propagation. Similarly, in the anomalous regime a decreasing dispersion profile can be used to compensate for the material losses to allow for soliton propagation, and even soliton compression to generate ultrashort pulses. Due to the broad optical transmission window of silicon, we anticipate that nonlinear pulse shaping in tapered silicon fibres and waveguides will find use not only in the telecoms band, but also extending into the mid-infrared for applications in the life sciences.

  9. Polymer optical fiber tapering using hot water

    NASA Astrophysics Data System (ADS)

    Mizuno, Yosuke; Ujihara, Hiroki; Lee, Heeyoung; Hayashi, Neisei; Nakamura, Kentaro

    2017-06-01

    We perform a pilot trial of highly convenient taper fabrication for polymer optical fibers (POFs) using hot water. A ∼380-mm-long POF taper is successfully fabricated, and its ∼150-mm-long waist has a uniform outer diameter of ∼230 µm. The shape is in good agreement with the theoretical prediction. The optical loss dependence on the strain applied to the waist shows an interesting behavior exhibiting three regimes, the origins of which are inferred by microscopic observations. We then discuss the controllability of the taper length.

  10. Endfire tapered slot antennas on dielectric substrates

    NASA Technical Reports Server (NTRS)

    Yngvesson, K. S.; Schaubert, D. H.; Korzeniowski, T. L.; Kollberg, E. L.; Thungren, T.

    1985-01-01

    Endfire-tapered slot antennas are suitable for many integrated circuit applications, imaging and phased arrays. An investigation of single elements of such antennas, including slots which are exponentially tapered (Vivaldi), linearly tapered, and constant width. For antennas of all types, a good general agreement is obtained for curves of beamwidth-versus-length, normalized to wavelength, when one compares the data with that for traveling-wave antennas published by Zucker (1961). An important condition for this agreement is that the effective dielectric thickness, defined in the text, is in a certain optimum range. This condition is qualitatively explained in terms of the theory for traveling-wave antennas.

  11. Characterizing optical polishing pitch

    NASA Astrophysics Data System (ADS)

    Varshneya, Rupal; DeGroote, Jessica E.; Gregg, Leslie L.; Jacobs, Stephen D.

    2003-05-01

    Characterization data for five experimental optical polishing pitch products were compared to those for corresponding standard commercial optical polishing pitches. The experimental pitches were tested for three physical properties: hardness, viscosity at 90°C, and softening point. A Shore A Durometer test was used to measure hardness. Viscosity data were collected using a Stony Brook Scientific falling needle viscometer. Softening point was determined using the ASTM D3104-97 method. Results demonstrate that the softest and the hardest batches of the experimental grades of optical pitch are comparable to the industry-accepted standards, while the other grades of pitch are not. The experimental methodology followed in this research may allow opticians to rapidly compare different brands of pitch to help identify batch-to-batch differences and control pitch quality before use.

  12. Central-wavelength-tunable multi-wavelength fiber laser based on micro-air gap cavity and tapered fiber structure

    NASA Astrophysics Data System (ADS)

    Chen, Jiao; Tong, Zhengrong; Yang, He; Zhang, Weihua; Xue, Lifang; Pan, Honggang

    2017-08-01

    A multi-wavelength erbium-doped fiber laser based on a micro-air gap cavity filter and the tapered fiber structure is proposed and demonstrated. The micro-air gap cavity filter is constructed by aligning two polished single mode fiber facets carefully through a capillary. Then a tapered fiber structure is applied to compose a cascaded filter with the micro-air gap cavity filter. According to the experiment, the transmission spectrum of the tapered fiber structure acts as the outer envelope of the cascaded structure, which is used as a tunable filter. Moreover, the periodically localized peaks of the tapered fiber structure are modulated by sinusoidal spectral response of the micro-air gap cavity filter. And the micro-air gap cavity filter acts as a comb filter, which determines the channel space of the cascaded filter structure. By using the above superimposed filter, four wavelengths with a wavelength spacing of about 1.20 nm are generated under the pump power of 270 mW. The side-mode suppression ratio of all lasing wavelengths is about 35 dB. The tapered fiber structure is fixed on a furnace, when the temperature varies from 30 °C to 120 °C, the first wavelength can be tuned within the range of 5.31 nm.

  13. Interoperator variability during polishing.

    PubMed

    Jones, Colin S; Billington, Richard W; Pearson, Gavin J

    2006-03-01

    The object of this study was to establish the 3 variables used in polishing by measuring the range of loads, speeds, and times used by practitioners when finishing and polishing samples of amalgam, resin composite, and glass-ionomer cement. These parameters could then be used to establish clinically relevant values that might optimize clinical finishing techniques. Samples of the 3 materials were attached to the load cell of a universal testing machine that was attached to an X-Y plotter. Practitioners were asked to finish the samples using 4 grades of a polishing disk system. Prior to using each grade of disk, the practitioner selected a speed. The sample was finished using one grade of disk until the practitioner was satisfied with the finish achieved. The process was then repeated with the next grade of disk. From the tracings for each disk the load and time were calculated. There was a wide variation in the loads, speeds, and times used by the practitioners to finish the 3 materials, and it was not possible to find any relationship among the 3 variables. It appeared that practitioners finished the materials in an arbitrary manner. No clear evidence was obtained to determine optimal combinations of load, speed, and time for finishing of amalgam, resin composite, or glass-ionomer cement. However, the results of this study indicate a range of values commonly used for each parameter in clinical practice, which could be useful for manufacturers in providing finishing instructions for their products.

  14. The Advantages of a Tapered Whisker

    PubMed Central

    Williams, Christopher M.; Kramer, Eric M.

    2010-01-01

    The role of facial vibrissae (whiskers) in the behavior of terrestrial mammals is principally as a supplement or substitute for short-distance vision. Each whisker in the array functions as a mechanical transducer, conveying forces applied along the shaft to mechanoreceptors in the follicle at the whisker base. Subsequent processing of mechanoreceptor output in the trigeminal nucleus and somatosensory cortex allows high accuracy discriminations of object distance, direction, and surface texture. The whiskers of terrestrial mammals are tapered and approximately circular in cross section. We characterize the taper of whiskers in nine mammal species, measure the mechanical deflection of isolated felid whiskers, and discuss the mechanics of a single whisker under static and oscillatory deflections. We argue that a tapered whisker provides some advantages for tactile perception (as compared to a hypothetical untapered whisker), and that this may explain why the taper has been preserved during the evolution of terrestrial mammals. PMID:20098714

  15. Influence of tooth preparation taper and cement type on recementation strength of complete metal crowns.

    PubMed

    Ayad, Mohamed F; Johnston, William M; Rosenstiel, Stephen F

    2009-12-01

    Clinical studies have shown that lack of retention is one of the major causes of fixed dental prosthesis failure. The purpose of this study was to determine the relationship between the convergence angle of a complete metal crown tooth preparation and the recementation strength for restorations cemented with conventional and adhesive cements. One hundred twenty artificial crowns were cast for standardized complete metal crown tooth preparations accomplished with the use of a milling machine on extracted human teeth. Three different tapers, 5, 12, and 25 degrees, were used (n=40). The crowns in each group were subdivided into 4 subgroups (n=10) according to the luting cement: zinc phosphate cement (Fleck's), glass ionomer cement (Ketac-Cem), and adhesive resin cements (Panavia 21 and C&B-Metabond). Retention was evaluated by measuring the tensile force required to dislodge the crowns from the tooth preparations in a universal testing machine. Subsequently, the tooth preparations were scraped clean and polished with prophylaxis paste, and the intaglio surfaces of the artificial crowns were ultrasonically cleaned and airborne-particle abraded with 50-mum aluminum oxide powder prior to recementation. The data were analyzed with 3-way repeated-measures ANOVA and Tukey's HSD test (alpha=.05). Analysis of measurements disclosed a significant difference for taper and luting cement (P<.001); however, their interaction was not significant. Also, there was a statistically significant difference between the retention of the first cementation and the second cementation (P<.001). However, the interaction was not significant with taper or cement. Regardless of the taper used, Panavia 21 cement exhibited the highest mean initial retention, but the difference was not significantly different from the recementation retentive strength. Tooth preparation taper and type of luting cement had a direct effect on the recementation strength of complete metal crowns.

  16. Tapered plug foam spray apparatus

    NASA Technical Reports Server (NTRS)

    Allen, Peter B. (Inventor)

    1996-01-01

    A two-component foam spray gun is readily disassembled for cleaning. It includes a body (1) with reactant (12, 14) and purge gas (16) inlet ports. A moldable valve packing (32) inside the body has a tapered conical interior surface (142), and apertures which match the reactant ports. A valve/tip (40) has a conical outer surface (48) which mates with the valve packing (32). The valve/tip (40) is held in place by a moldable packing washer (34), held at non-constant pressure by a screw (36, 38). The interior of the valve/tip (40) houses a removable mixing chamber (50). The mixing chamber (50) has direct flow orifices (60) and an auxiliary flow path (58, 60) which ameliorate pressure surges. The spray gun can be disassembled for cleaning without disturbing the seal, by removing the valve/tip (40) to the rear, thereby breaking it free of the conical packing. Rotation of the valve/tip (40) relative to the body (1) shuts off the reactant flow, and starts the purge gas flow.

  17. Backscatter Coefficient Estimation Using Tapers with Gaps

    PubMed Central

    Luchies, Adam C.; Oelze, Michael L.

    2015-01-01

    When using the backscatter coefficient (BSC) to estimate quantitative ultrasound parameters such as the effective scatterer diameter (ESD) and the effective acoustic concentration (EAC), it is necessary to assume that the interrogated medium contains diffuse scatterers. Structures that invalidate this assumption can affect the estimated BSC parameters in terms of increased bias and variance and decrease performance when classifying disease. In this work, a method was developed to mitigate the effects of echoes from structures that invalidate the assumption of diffuse scattering, while preserving as much signal as possible for obtaining diffuse scatterer property estimates. Backscattered signal sections that contained nondiffuse signals were identified and a windowing technique was used to provide BSC estimates for diffuse echoes only. Experiments from physical phantoms were used to evaluate the effectiveness of the proposed BSC estimation methods. Tradeoffs associated with effective mitigation of specular scatterers and bias and variance introduced into the estimates were quantified. Analysis of the results suggested that discrete prolate spheroidal (PR) tapers with gaps provided the best performance for minimizing BSC error. Specifically, the mean square error for BSC between measured and theoretical had an average value of approximately 1.0 and 0.2 when using a Hanning taper and PR taper respectively, with six gaps. The BSC error due to amplitude bias was smallest for PR (Nω = 1) tapers. The BSC error due to shape bias was smallest for PR (Nω = 4) tapers. These results suggest using different taper types for estimating ESD versus EAC. PMID:25189857

  18. Backscatter coefficient estimation using tapers with gaps.

    PubMed

    Luchies, Adam C; Oelze, Michael L

    2015-04-01

    When using the backscatter coefficient (BSC) to estimate quantitative ultrasound parameters such as the effective scatterer diameter (ESD) and the effective acoustic concentration (EAC), it is necessary to assume that the interrogated medium contains diffuse scatterers. Structures that invalidate this assumption can affect the estimated BSC parameters in terms of increased bias and variance and decrease performance when classifying disease. In this work, a method was developed to mitigate the effects of echoes from structures that invalidate the assumption of diffuse scattering, while preserving as much signal as possible for obtaining diffuse scatterer property estimates. Backscattered signal sections that contained nondiffuse signals were identified and a windowing technique was used to provide BSC estimates for diffuse echoes only. Experiments from physical phantoms were used to evaluate the effectiveness of the proposed BSC estimation methods. Tradeoffs associated with effective mitigation of specular scatterers and bias and variance introduced into the estimates were quantified. Analysis of the results suggested that discrete prolate spheroidal (PR) tapers with gaps provided the best performance for minimizing BSC error. Specifically, the mean square error for BSC between measured and theoretical had an average value of approximately 1.0 and 0.2 when using a Hanning taper and PR taper respectively, with six gaps. The BSC error due to amplitude bias was smallest for PR (Nω = 1) tapers. The BSC error due to shape bias was smallest for PR (Nω = 4) tapers. These results suggest using different taper types for estimating ESD versus EAC. © The Author(s) 2014.

  19. Modular calcar replacement prosthesis with strengthened taper junction in total hip arthroplasty.

    PubMed

    Lombardi, Adolph V; Berend, Keith R; Mallory, Thomas H; Adams, Joanne B

    2007-01-01

    Whereas femoral component modularity allows the surgeon to address a variety of femoral defects in complex total hip arthroplasty (THA), breakage of modular stems is a known complication that typically occurs at the taper junction. In response, a proprietary process of taper roller-hardening that increases taper strength by a factor of 3.5 was introduced in 1999. The authors reviewed a consecutive series of patients by a single surgeon who underwent cementless revision or difficult primary THA with a taper roller-hardened modular calcar replacement prosthesis, and have the potential for a minimum of two-year follow up. In 116 patients, 123 hips were involved. Two surgeries were primary, 101 were revision/conversion, 18 were for reimplantation after treatment of infection, and two were intramedullary total femur constructs, one of which was a reimplantation after sepsis. The patients' ages at surgery averaged 71 years, and BMIs averaged 28.12 kg/m2. Nine of the patients, all with single hip involvement, were lost to contact. Twenty-one patients, three of whom had bilateral hip involvement, expired during the follow-up period with implant outcome known. Follow up in the patients who survived averaged 44 (range: 18-78) months. Six femoral components have been revised: two (1.6%) due to recurrent sepsis, three (2.4%) due to sepsis, one (0.8%) from periprosthetic fracture, and none from septic loosening or component breakage. Survivorship with aseptic loosening as the end-point was 100%. In this series, roller-hardening appears to improve the durability of the tapered junction. No roller-hardened modular calcar devices have failed due to component breakage. However, their use is not recommended in the totally deficient proximal femur, as fatigue breaks of distally fixed monoblock extensively coated stems have been reported. Caution is advised when potting or anchoring any stem in the femoral diaphysis without reconstituting proximal bone stock and support.

  20. Pseudotumour formation due to tribocorrosion at the taper interface of large diameter metal on polymer modular total hip replacements.

    PubMed

    Cook, Richard B; Bolland, Benjamin J R F; Wharton, Julian A; Tilley, Simon; Latham, Jeremy M; Wood, Robert J K

    2013-09-01

    We present an in-depth failure analysis of two large diameter bearing metal-on-polymer (MoP) modular total hip replacements, which have required revision surgery due to pseudotumour formation. The failure analysis showed a discrete pattern of material loss from the distal end of the head taper/stem trunnion interface. We postulate that the use of a proximal contacting taper design had provided insufficient mechanical locking between the head and the stem, enabling the head to toggle on the trunnion. In addition, the difference in angle between the taper and the trunnion formed a crevice between the two components. Through a combination of crevice environment, mechanically assisted corrosion, mechanical wear and erosion; debris and metal-ions have been released resulting in the adverse local tissue reactions (ALTR).

  1. Training theory and taper: validation in triathlon athletes.

    PubMed

    Banister, E W; Carter, J B; Zarkadas, P C

    1999-01-01

    This paper defines a training theory with which to predict the effectiveness of various formats of taper in optimizing physical performance from a standardized period of training and taper. Four different taper profiles: step reduction vs exponential (exp) decay and fast vs slow exp decay tapers, were simulated in a systems model to predict performance p(t) resulting from a standard square-wave quantity of training for 28 days. The relative effectiveness of each of the profiles in producing optimal physical improvement above pre-taper criterion physical test standards (running and cycle ergometry) was determined. Simulation showed that an exp taper was better than a step-reduction taper, and a fast exp decay taper was superior to a slow exp decay taper. The results of the simulation were tested experimentally in field trials to assess the correspondence between simulation and real-training criterion physical tests in triathlon athletes. The results showed that the exp taper (tau = 5 days) group made a significantly greater improvement above a pre-taper standard (P < or = 0.05) than the step-reduction taper group in cycle ergometry, and was better, but not significantly so, in a 5-km run. A fast exp taper group B (tau = 4 days) performed significantly better (P < or = 0.05) in maximal, cycle ergometry above a pre-taper training standard than a slow exp taper group A (tau = 8 days) and was improved more, but not significantly so, than group A in a 5-km criterion run. The mean improvement on both physical tests by exp decay taper groups all increased significantly (P < or = 0.05) above their pre-taper training standard. Maximum oxygen uptake increased significantly in a group of eight remaining athletes during 2 weeks of final taper after three athletes left early for final preparations at the race site.

  2. Electromechanical polishing of metal spheres

    SciTech Connect

    Miller, N.E.; Engelhaupt, D.E.

    1980-04-01

    Equipment has been developed to electromechanically polish metal spheres. Mechanical polishing is accomplished by the action of three cup-shaped laps which rotate against the sphere. An abrasive slurry containing an electrolyte is continuously applied to the sphere and laps. Electrochemical etching is accomplished by applying a positive potential to two of the laps and a negative potential to the third.

  3. Polish Americans. Second, Revised Edition.

    ERIC Educational Resources Information Center

    Lopata, Helen Znaniecka

    This book examines Polonia, the Polish ethnic community in America created by three giant waves of immigration between 1880 and 1990. The complicated history of this ethnic group is reflected in the lives of increasing numbers of Polish Americans, including recent immigrants brought by political and economic changes, as they achieve middle class…

  4. Polishing technique for beryllium mirror

    NASA Technical Reports Server (NTRS)

    Froechtenigt, J. F.

    1976-01-01

    Performance tests, accomplished by inserting entire X ray telescope and polished mirror into vacuum line 67 m long and taking photographs of an X ray resolution source, indicate that polishing increases mirror efficiency from 0.06 percent for X rays at 0.8 nm and increases resolution from 15 to 3.75 arc-seconds.

  5. Notions Catalog. Polish Functional Grammar.

    ERIC Educational Resources Information Center

    Woytak, Lidia

    The Polish notions catalog systematizes a variety of informational codes used in Polish, resulting in lists of notions, each presented from a structural perspective. Where applicable, they are accompanied by a morphological component, structural chart, semantic description, frequentative expressions, and related vocabulary items. The notions…

  6. Notions Catalog. Polish Functional Grammar.

    ERIC Educational Resources Information Center

    Woytak, Lidia

    The Polish notions catalog systematizes a variety of informational codes used in Polish, resulting in lists of notions, each presented from a structural perspective. Where applicable, they are accompanied by a morphological component, structural chart, semantic description, frequentative expressions, and related vocabulary items. The notions…

  7. Reading Authentic Polish, Volume II.

    ERIC Educational Resources Information Center

    Walczynski, Waldemar

    The second volume on reading authentic Polish is the continuation of a supplementary textbook to be used either in the classroom or in independent study. The materials included in it are unaltered authentic texts from Polish newspapers, magazines, and other mass media that provide exposure to the context and format of everyday reading matter. The…

  8. [Lysenkoism in Polish botany].

    PubMed

    Köhler, Piotr

    2008-01-01

    Lysenkoism in Poland was never an autonomous phenomenon. The whole array of reasons for which it appeared in Polish science would require a separate study--here it only needs to be pointed out that the major reasons included terror on the part of the security service, lawlessness, the ubiquitous atmosphere of intimidation and terror, censorship, the diminishing sphere of civil liberties, political show trials, propaganda and denunciations. An important role in facilitating the introduction of Lysenkoism was played also by the reorganization of science after World War Two, the isolation of Polish science from science in the West, as well as the damage it had suffered during the war. At first, Lysenkoism was promoted in Poland by a small group of enthusiastic and uncritical proponents. A overview of the events connected with the ten years of Lysenkoism in Poland (end of 1948--beginning of 1958) shows a two-tier picture of how the 'idea' was propagated. The first tier consisted in the activities of the Association of Marxist Naturalists [Koło Przyrodników-Marksistów], which it engaged in since the end of 1948. The Association was later transformed into a Union of Marxist Naturalists, and this in turn merged, in 1952, with the Copernican Society of Polish Naturalists [Polskie Towarzystwo Przyrodników im. Kopernika]. It was that society which promoted Lysenkoism longest, until the end of 1956. The propaganda and training activities of the circle and the society prepared ground for analogous activities of the newly formed Polish Academy of Science (PAN), which--since its very establishment in 1952--engaged in promoting Lysenkoism through its Second Division. These activities were aimed at naturalists, initially at those who were prominent scientists (eg. the conference at Kuźnice, 1950/1951), and then at those who were only starting their academic career (including national courses in new biology at Dziwnów, 1952, or Kortowo, 1953 and 1955). The end to promoting

  9. Tapered polysilicon core fibers for nonlinear photonics.

    PubMed

    Suhailin, Fariza H; Shen, Li; Healy, Noel; Xiao, Limin; Jones, Maxwell; Hawkins, Thomas; Ballato, John; Gibson, Ursula J; Peacock, Anna C

    2016-04-01

    We propose and demonstrate a novel approach to obtaining small-core polysilicon waveguides from the silicon fiber platform. The fibers were fabricated via a conventional drawing tower method and, subsequently, tapered down to achieve silicon core diameters of ∼1  μm, the smallest optical cores for this class of fiber to date. Characterization of the material properties have shown that the taper process helps to improve the local crystallinity of the silicon core, resulting in a significant reduction in the material loss. By exploiting the combination of small cores and low losses, these tapered fibers have enabled the first observation of nonlinear transmission within a polycrystalline silicon waveguide of any type. As the fiber drawing method is highly scalable, it opens a route for the development of low-cost and flexible nonlinear silicon photonic systems.

  10. Turbine airfoil fabricated from tapered extrusions

    SciTech Connect

    Marra, John J

    2013-07-16

    An airfoil (30) and fabrication process for turbine blades with cooling channels (26). Tapered tubes (32A-32D) are bonded together in a parallel sequence, forming a leading edge (21), a trailing edge (22), and pressure and suction side walls (23, 24) connected by internal ribs (25). The tapered tubes may be extruded without camber to simplify the extrusion process, then bonded along matching surfaces (34), forming a non-cambered airfoil (28), which may be cambered in a hot forming process and cut (48) to length. The tubes may have tapered walls that are thinner at the blade tip (T1) than at the base (T2), reducing mass. A cap (50) may be attached to the blade tip. A mounting lug (58) may be forged (60) on the airfoil base and then machined, completing the blade for mounting in a turbine rotor disk.

  11. Enhancing sensitivity of biconical tapered fiber sensors with multiple passes through the taper

    NASA Astrophysics Data System (ADS)

    Cohoon, Gregory; Boyter, Chris; Errico, Michael; Vandervoort, Kurt; Salik, Ertan

    2010-03-01

    A single biconical fiber taper is a simple and low-cost yet powerful sensor. With a distinct strength in refractive index (RI) sensing, biconical tapered fiber sensors can find their place in handheld sensor platforms, especially as biosensors that are greatly needed in health care, environmental protection, food safety, and biodefense. We report doubling of sensitivity for these sensors with two passes through the tapered region, which becomes possible through the use of sensitive and high-dynamic-range photodetectors. In a proof-of-principle experiment, we measured transmission through the taper when it was immersed in isopropyl alcohol-water mixtures of varying concentrations, in which a thin gold layer at the tip of the fiber acted as a mirror enabling two passes through the tapered region. This improved the sensitivity from 0.43 dB/vol % in the single-pass case to 0.78 dB/vol % with two passes through the taper. The refractive index detection limit was estimated to be ~1.2×10-5 RI units (RIU) and ~0.6×10-5 RIU in the single- and double-pass schemes, respectively. We predict that further enhancement of sensitivity may be achieved with a higher number of passes through the taper.

  12. Two critical tapers in a single wedge

    NASA Astrophysics Data System (ADS)

    Smit, J.; Burg, J.-P.; Brun, J.-P.

    2009-04-01

    Thrust involving a ductile décollement (e.g. salt, over-pressured shales) like Zagros, Jura, Pakistan Salt Ranges, Cascades and Makran have in common a small cross-sectional taper, attributed to large thrust spacing and fast frontward propagation above the ductile décollement. Such a low cross-sectional taper has been analytically explained by approximating the ductile layer as a horizon with negligible shear strength. We tested the development of thrust wedges involving a ductile basal décollement of uniform shear strength by means of laboratory experiments. The model consists of a sand layer with initial wedge geometry and a basal ductile décollement of constant thickness and shear strength made of silicone putty. 30% of bulk shortening is applied to the wedge at constant velocity. Thrusting starts in the middle of the wedge, followed by in-sequence frontward propagation. The back part of the wedge, between backstop and the closest thrust, remains undeformed; it passively advances over the base without internal deformation. It appears that both domains have different critical tapers. The inner domain is in a critical state from the onset of shortening (i.e. the initial wedge is already critical), while the frontal domain steadily acquires a state of critical taper by thrusting. This result is at variance with the classical assumption that shortening of a wedge made of homogeneous layers creates a single critical taper. The experimental thrust wedges do show other features characteristic for weak décollement wedges like narrow cross-sectional taper, large thrust spacing and variety in thrust geometries. Application of the results to natural thrust wedges like the Jura Mountains could shed new light on their development and geometry at depth.

  13. Subjective Quality of Life of Polish, Polish-Immigrant, and Polish-American Elderly.

    ERIC Educational Resources Information Center

    Berdes, Celia; Zych, Adam A.

    2000-01-01

    Compares subjective quality of life of elderly Poles living in Poland, and Polish immigrants and Polish-American ethnics living in Chicago as part of a secondary data analysis of a study initially conducted in Poland. Conclusions lend support to the idea that U.S.-born elderly people and elderly immigrants to the United States have a significantly…

  14. Stress intensity factor in a tapered specimen

    NASA Technical Reports Server (NTRS)

    Xue-Hui, L.; Erdogan, F.

    1985-01-01

    The general problem of a tapered specimen containing an edge crack is formulated in terms of a system of singular integral equations. The equations are solved and the stress intensity factor is calculated for a compact and for a slender tapered specimen, the latter simulating the double cantilever beam. The results are obtained primarily for a pair of concentrated forces and for crack surface wedge forces. The stress intensity factors are also obtained for a long strip under uniform tension which contains inclined edge cracks.

  15. Lightwave coupler utilizing a tapered buffer layer.

    PubMed

    Kishioka, K

    1988-06-01

    We discuss the performance of a lightwave coupler utilizing a tapered buffer layer. The coupler with a ridge waveguide is fabricated on a glass substrate and high coupling efficiencies of 75% and 50% are measured for the operations of coupling from the waveguide to a light beam and from the laser beam into the waveguide, respectively. Further, experimental results of the rigid connection between the optical fiber and the waveguide are demonstrated. We also describe how the coupler differs from the conventional tapered guiding-layer coupler.

  16. Polishing of denture base acrylic resin with chairside polishing kits: an SEM and surface roughness study.

    PubMed

    Chatzivasileiou, Konstantinos; Emmanouil, Ioannis; Kotsiomiti, Eleni; Pissiotis, Argirios

    2013-01-01

    Heat-cured acrylic resin specimens were polished using either conventional laboratory polishing, sandpaper, or three commercial chairside kits. The surface roughness of the polished specimens was measured with a contact profilometer. Scanning electron microscopy was used to obtain microphotographs of the polished surfaces. Laboratory polishing produced the smoothest surfaces in all cases, while sandpaper application produced the roughest. Use of the chairside polishing kits resulted in significantly rougher surfaces compared to those produced by laboratory polishing. Nonetheless, polishing of trimmed denture bases using chairside polishing kits is an effective alternative procedure for cases in which the laboratory procedure is not applicable.

  17. 77 FR 50716 - Tapered Roller Bearings From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-22

    ... COMMISSION Tapered Roller Bearings From China Determination On the basis of the record \\1\\ developed in the... antidumping duty order on tapered roller bearings from China would be likely to lead to continuation or... Publication 4343 (August 2012), entitled Tapered Roller Bearings from China: Investigation No. 731-TA-344...

  18. Recent Changes in the Spoken Polish Language.

    ERIC Educational Resources Information Center

    Birkenmayer, Sigmund S.

    Both spoken and written Polish have undergone profound changes during the past twenty-eight years. The increasing urbanization of Polish culture and the forced change in Polish society are the main factors influencing the change in the language. Indirect evidence of changes which have occurred in the vocabulary and idioms of spoken Polish in the…

  19. Radial Distance Estimation with Tapered Whisker Sensors.

    PubMed

    Ahn, Sejoon; Kim, DaeEun

    2017-07-19

    Rats use their whiskers as tactile sensors to sense their environment. Active whisking, moving whiskers back and forth continuously, is one of prominent features observed in rodents. They can discriminate different textures or extract features of a nearby object such as size, shape and distance through active whisking. There have been studies to localize objects with artificial whiskers inspired by rat whiskers. The linear whisker model based on beam theory has been used to estimate the radial distance, that is, the distance between the base of the whisker and a target object. In this paper, we investigate deflection angle measurements instead of forces or moments, based on a linear tapered whisker model to see the role of tapered whiskers found in real animals. We analyze how accurately this model estimates the radial distance, and quantify the estimation errors and noise sensitivity. We also compare the linear model simulation and nonlinear numerical solutions. It is shown that the radial distance can be estimated using deflection angles at two different positions on the tapered whisker. We argue that the tapered whisker has an advantage of estimating the radial distance better, as compared to an untapered whisker, and active sensing allows that estimation without the whisker's material property and thickness or the moment at base. In addition, we investigate the potential of passive sensing for tactile localization.

  20. Compatible taper algorithms for California hardwoods

    Treesearch

    James W. Flewelling

    2007-01-01

    For 13 species of California hardwoods, cubic volume equations to three merchantability standards had been developed earlier. The equations predict cubic volume from the primary bole, forks, and branches, but do not differentiate between the sources of the wood. The Forest Inventory and Analysis (FIA) program needed taper equations that are compatible with the volume...

  1. Tapered LSO arrays for small animal PET

    NASA Astrophysics Data System (ADS)

    Yang, Yongfeng; St. James, Sara; Wu, Yibao; Du, Huini; Qi, Jinyi; Farrell, Richard; Dokhale, Purushottam A.; Shah, Kanai S.; Vaigneur, Keith; Cherry, Simon R.

    2011-01-01

    By using detectors with good depth encoding accuracy (~2 mm), an animal PET scanner can be built with a small ring diameter and thick crystals to simultaneously obtain high spatial resolution and high sensitivity. However, there will be large wedge-shaped gaps between detector modules in such a scanner if traditional cuboid crystal arrays are used in a polygonal arrangement. The gaps can be minimized by using tapered scintillator arrays enabling the sensitivity of the scanner to be further improved. In this work, tapered lutetium oxyorthosilicate (LSO) arrays with different crystal dimensions and different combinations of inter-crystal reflector and crystal surface treatments were manufactured and their performance was evaluated. Arrays were read out from both ends by position-sensitive avalanche photodiodes (PSAPDs). In the optimal configuration, arrays consisting of 0.5 mm LSO elements could be clearly resolved and a depth of interaction resolution of 2.6 mm was obtained for a 20 mm thick array. For this tapered array, the intrinsic spatial is degraded from 0.67 to 0.75 mm compared to a standard cuboidal array with similar dimensions, while the increase in efficiency is 41%. Tapered scintillator arrays offer the prospect of improvements in sensitivity and sampling for small-bore scanners, without large increases in manufacturing complexity.

  2. Radial Distance Estimation with Tapered Whisker Sensors

    PubMed Central

    Ahn, Sejoon; Kim, DaeEun

    2017-01-01

    Rats use their whiskers as tactile sensors to sense their environment. Active whisking, moving whiskers back and forth continuously, is one of prominent features observed in rodents. They can discriminate different textures or extract features of a nearby object such as size, shape and distance through active whisking. There have been studies to localize objects with artificial whiskers inspired by rat whiskers. The linear whisker model based on beam theory has been used to estimate the radial distance, that is, the distance between the base of the whisker and a target object. In this paper, we investigate deflection angle measurements instead of forces or moments, based on a linear tapered whisker model to see the role of tapered whiskers found in real animals. We analyze how accurately this model estimates the radial distance, and quantify the estimation errors and noise sensitivity. We also compare the linear model simulation and nonlinear numerical solutions. It is shown that the radial distance can be estimated using deflection angles at two different positions on the tapered whisker. We argue that the tapered whisker has an advantage of estimating the radial distance better, as compared to an untapered whisker, and active sensing allows that estimation without the whisker’s material property and thickness or the moment at base. In addition, we investigate the potential of passive sensing for tactile localization. PMID:28753949

  3. 60 GHz Tapered Transmission Line Resonators

    DTIC Science & Technology

    2008-09-15

    DARPA TEAM program (contract no. DAAB07-02-1- L428 ), Motorola, and the UC-Micro program. 60 GHz Tapered Transmission Line Resonators by...0403427, wafer fabrication donation by STMicroelectronics, DARPA TEAM program (con- tract no. DAAB07-02-1- L428 ), Motorola, and the UC-Micro program. 1

  4. Microstrip transmission line tapers on ferrites

    SciTech Connect

    Albuquerque, M.R.; dAssuncao, A.G.; Lima, F.

    1997-04-01

    The spectral domain approach is employed to perform a theoretical investigation of tapered microstrip lines on magnetized ferrite substrates. A linear variation of the conducting strip width along the direction of propagation is considered. The analysis takes into account the effects of the applied dc magnetic bias field in the transmission characteristics of these structures. The properties of the taper are determined by a model based on a segmentation of the considered line into uniform microstrip line subsections. Normalized phase constants and characteristic impedances are obtained by using the Hertz vector potentials method and Galerkin numerical technique. Numerical results are presented to show the taper input parameters as a function of the load impedance, geometrical dimensions, operating frequency, and ferrite parameters, considering the orientation and magnitude changes of the biasing magnetic-field {bold H}{sub 0}. The results agree fairly well with those available in the literature for tapered microstrip lines on isotropic dielectric substrates. {copyright} {ital 1997 American Institute of Physics.}

  5. Tapered LSO Arrays for Small Animal PET

    PubMed Central

    Yang, Yongfeng; James, Sara St.; Wu, Yibao; Du, Huini; Qi, Jinyi; Farrell, Richard; Dokhale, Purushottam A.; Shah, Kanai S.; Vaigneur, Keith; Cherry, Simon R.

    2011-01-01

    By using detectors with good depth encoding accuracy (~ 2 mm), an animal PET scanner can be built with a small ring diameter and thick crystals to simultaneously obtain high spatial resolution and high sensitivity. However, there will be large wedge-shaped gaps between detector modules in such a scanner if traditional cuboid crystal arrays are used in a polygonal arrangement. The gaps can be minimized by using tapered scintillator arrays enabling the sensitivity of the scanner to be further improved. In this work, tapered lutetium oxyorthosilicate (LSO) arrays with different crystal dimensions and different combinations of inter-crystal reflector and crystal surface treatments were manufactured and their performance was evaluated. Arrays were read out from both ends by position-sensitive avalanche photodiodes (PSAPDs). In the optimal configuration, arrays consisting of 0.5 mm LSO elements could be clearly resolved and a depth of interaction resolution of 2.6 mm was obtained for a 20-mm thick array. For this tapered array, the intrinsic spatial is degraded from 0.67 mm to 0.75 mm compared to a standard cuboidal array with similar dimensions, while the increase in efficiency is 41%. Tapered scintillator arrays offer the prospect of improvements in sensitivity and sampling for small-bore scanners, without large increases in manufacturing complexity. PMID:21119228

  6. Lysenko affair and Polish botany.

    PubMed

    Köhler, Piotr

    2011-01-01

    This article describes the slight impact of Lysenkoism upon Polish botany. I begin with an account of the development of plant genetics in Poland, as well as the attitude of scientists and the Polish intelligentsia toward Marxist philosophy prior to the World War II. Next I provide a short history of the introduction and demise of Lysenkoism in Polish science, with a focus on events in botany, in context with key events in Polish science from 1939 to 1958. The article outlines the little effects of Lysenkoism upon botanists and their research, as well as how botanists for the most part rejected what was often termed the "new biology." My paper shows that though Lysenko's theories received political support, and were actively promoted by a small circle of scientists and Communist party activists, they were never accepted by most botanists. Once the political climate in Poland altered after the events of 1956, Lysenko's theories were immediately abandoned.

  7. Tooth polishing: The current status

    PubMed Central

    Sawai, Madhuri Alankar; Bhardwaj, Ashu; Jafri, Zeba; Sultan, Nishat; Daing, Anika

    2015-01-01

    Healthy teeth and gums make a person feel confident and fit. As people go about their daily routines and with different eating and drinking habits, the tooth enamel turns yellowish or gets stained. Polishing traditionally has been associated with the prophylaxis procedure in most dental practices, which patients know and expect. However, with overzealous use of polishing procedure, there is wearing of the superficial tooth structure. This would lead to more accumulation of local deposits. Also, it takes a long time for the formation of the fluoride-rich layer of the tooth again. Hence, now-a-days, polishing is not advised as a part of routine oral prophylaxis procedure but is done selectively based on the patients’ need. The article here, gives an insight on the different aspects of the polishing process along with the different methods and agents used for the same. PMID:26392683

  8. Astronarium - Filmography of Polish Astronomy

    NASA Astrophysics Data System (ADS)

    Radajewski, Bogumił; Mikołajewski, Maciej; Czart, Krzysztof; Guz, Iwona; Rubaszewski, Adam; Stelmach, Tomasz

    2016-06-01

    ``Astronarium'' is a series of TV programs about astronomy and space research co-produced by the Polish Astronomical Society and Polish Television. It has been planned for three seasons and 34 episodes in total (8, 13 and 13 per season). The first season was presented in March and April 2015 and the second started in September 2015. The third one is planned for 2016. ``Astronarium'' has been broadcast on the nationwide channel TVP Regionalna, which later changed its name to TVP 3.

  9. XXXVI Polish Astronomical Society Meeting

    NASA Astrophysics Data System (ADS)

    Różańska, Agata; Bejger, Michał

    2014-12-01

    XXXVI meeting of Polish Astronomical Society was held in Warsaw on Sept. 11-14, 2013. The conference brought together 150 astronomers working in different institutes in Poland and abroad. The highlight of the Congress was the first awarding of the Paczynski's Medal. The first laureate of the Medal is Professor Martin Rees from University of Cambridge. Medal was given by the President of the Polish Astronomical Society prof. Bozena Czerny.

  10. Ion Polishing of Optical Surfaces

    DTIC Science & Technology

    1976-09-01

    near normal incidence, leaving the surface damaged and roughened. With the ion polisher used here, a scanned and focused beam of relatively low energy ...operating conditions. Briefly, the polisher employs sputtering by a focused beam of relatively low energy Xe ions incident on the sample surface at...The combination of low ion energy , glancing angle of incidence, rastering, and sample rotation are expected to produce a smoothing of the surface

  11. Radiation losses of step-tapered channel waveguides.

    PubMed

    Marcuse, D

    1980-11-01

    We compute the radiation losses of a rectangular dielectric waveguide (integrated optics channel waveguide) that is tapered so that its wider cross-sectional dimension increases by roughly a factor of three while its narrow dimension remains constant. As the waveguide widens its refractive index decreases to ensure that the waveguide supports only one guided mode. The taper is approximated by a discontinuous staircase curve. A rectangular waveguide taper of 2-microm thickness, tapering from 3- to 10-microm width through fourteen steps of 0.25-microm height, has a minimum loss (at 0.6328-microm wavelength) of 0.13 dB for a 200-microm taper length.

  12. Electrochemical polishing of notches

    DOEpatents

    Kephart, A.R.; Alberts, A.H.

    1989-02-21

    An apparatus and method are disclosed for the selective electrochemical polishing of a lateral tip of a deep longitudinal notch in a work piece used to test crack initiation properties of materials. A DC power source is connected to the work piece and to an electrode disposed laterally along the distal end of an insulated body which is inserted in the longitudinal notch. The electrode and distal end of the body are disposed along the tip of the notch, but are spaced from the notch so as to provide a lateral passage for an electrolyte. The electrolyte is circulated through the passage so that the electrolyte only contacts the work piece adjacent the passage. Conveniently, the electrolyte is circulated by use of an inlet tube and an outlet tube provided at opposite ends of the passage. These tubes are preferably detachably located adjacent the ends of the passage and suitable seals are provided. A holding device including arms to which the tubes are attached is conveniently used to rapidly and easily locate the test specimen with the passage aligned with the tubes. The electrode is preferably a wire which is located in grooves along the distal end of the insulated body and up one side of the body or a plastic sheath insulated thin metal strip. 4 figs.

  13. Electrochemical polishing of notches

    DOEpatents

    Kephart, Alan R.; Alberts, Alfred H.

    1989-01-01

    An apparatus and method are disclosed for the selective electrochemical polishing of a lateral tip of a deep longitudinal notch in a work piece used to test crack initiation properties of materials. A DC power source is connected to the work piece and to an electrode disposed laterally along the distal end of an insulated body which is inserted in the longitudinal notch. The electrode and distal end of the body are disposed along the tip of the notch, but are spaced from the notch so as to provide a lateral passage for an electrolyte. The electrolyte is circulated through the passage so that the electrolyte only contacts the work piece adjacent the passage. Conveniently, the electrolyte is circulated by use of an inlet tube and an outlet tube provided at opposite ends of the passage. These tubes are preferably detachably located adjacent the ends of the passage and suitable seals are provided. A holding device including arms to which the tubes are attached is conveniently used to rapidly and easily locate the test specimen with the passage aligned with the tubes. The electrode is preferably a wire which is located in grooves along the distal end of the insulated body and up one side of the body or a plastic sheath insulated thin metal strip.

  14. Elastic emission polishing

    SciTech Connect

    Loewenthal, M.; Loseke, K.; Dow, T.A.; Scattergood, R.O.

    1988-12-01

    Elastic emission polishing, also called elastic emission machining (EEM), is a process where a stream of abrasive slurry is used to remove material from a substrate and produce damage free surfaces with controlled surface form. It is a noncontacting method utilizing a thick elasto-hydrodynamic film formed between a soft rotating ball and the workpiece to control the flow of the abrasive. An apparatus was built in the Center, which consists of a stationary spindle, a two-axis table for the workpiece, and a pump to circulate the working fluid. The process is controlled by a programmable computer numerical controller (CNC), which presently can operate the spindle speed and movement of the workpiece in one axis only. This apparatus has been used to determine material removal rates on different material samples as a function of time, utilizing zirconium oxide (ZrO{sub 2}) particles suspended in distilled water as the working fluid. By continuing a study of removal rates the process should become predictable, and thus create a new, effective, yet simple tool for ultra-precision mechanical machining of surfaces.

  15. [Polish health care system].

    PubMed

    Piontkovski, V; Novakovska, L; Pasternak, V

    2013-01-01

    The purpose of the discussion is to evaluate certain aspects of the Polish health care system - its ability to respond to contemporary dynamic social, economic and epidemiological changes (including the spread of chronic diseases, aging population or family crisis - its possibilities for providing care of the sick). The analysis of such a problem was based on a critically-oriented perspective that is developed in the field of the sociology of health and illness. The text pays particular attention to the problem of deepening social inequalities, which can be considered as one of the major factors that hinder access to health care and influence poorer health condition: In this context the mechanism of "saving health" and borrowing in order to satisfy the health needs in the face of financial difficulties was mentioned. Moreover, the text includes the attempt to evaluate the effectiveness of health promo- tion programs in our country as potentially the most effective way of raising the level of public health. There is also the issue of public confidence in health care institutions and the approval of attempts towards reforming the medical system in our country. A separate part of the discussion was devoted to criticism of the idea of reducing the role of the state in the health care sector.

  16. Impaction allograft with cement for the revision of the femoral component. A minimum 39-month follow-up study with the use of the Exeter stem in Asian hips

    PubMed Central

    Kim, Min-Young; Suh, Yoo-Sung

    2006-01-01

    We report the results of impaction bone grafting of the femoral side in revision total hip arthroplasty in Asian hips (South Korean patients) in which the surgery was performed with the use of the Exeter stem. The minimum follow-up was 39 months (mean, 48.4; range, 39–66). There was subsidence of the cement-graft interface (<1 mm) in three hips (5%), of the stem-cement interface (<1 mm) in 12 hips (21%) and of the stem-cement interface (1–2 mm) in 14 hips (25%). Five hips (9%) developed intraoperative femoral fracture and two hips (4%) femoral perforation in revision. The complications of femoral fracture and subsidence did not have an adverse effect on the final clinical outcomes. The impaction of fresh-frozen allograft and use of a cemented, polished, tapered stem (Exeter stem) were also successful with good clinical and radiographic outcomes in our study of Asian hips (South Korean patients). However, we used smaller stems than the usual ones used for Western patients because of the smaller femur sizes. PMID:16964487

  17. Transverse Emittance Reduction with Tapered Foil

    SciTech Connect

    Jiao, Yi; Chao, Alex; Cai, Yunhai; /SLAC

    2011-12-09

    The idea of reducing transverse emittance with tapered energy-loss foil is proposed by J.M. Peterson in 1980s and recently by B. Carlsten. In this paper, we present the physical model of tapered energy-loss foil and analyze the emittance reduction using the concept of eigen emittance. The study shows that, to reduce transverse emittance, one should collimate at least 4% of particles which has either much low energy or large transverse divergence. The multiple coulomb scattering is not trivial, leading to a limited emittance reduction ratio. Small transverse emittances are of essential importance for the accelerator facilities generating free electron lasers, especially in hard X-ray region. The idea of reducing transverse emittance with tapered energy-loss foil is recently proposed by B. Carlsten [1], and can be traced back to J.M. Peterson's work in 1980s [2]. Peterson illustrated that a transverse energy gradient can be produced with a tapered energy-loss foil which in turn leads to transverse emittance reduction, and also analyzed the emittance growth from the associated multiple coulomb scattering. However, what Peterson proposed was rather a conceptual than a practical design. In this paper, we build a more complete physical model of the tapered foil based on Ref. [2], including the analysis of the transverse emittance reduction using the concept of eigen emittance and confirming the results by various numerical simulations. The eigen emittance equals to the projected emittance when there is no cross correlation in beam's second order moments matrix [3]. To calculate the eigen emittances, it requires only to know the beam distribution at the foil exit. Thus, the analysis of emittance reduction and the optics design of the subsequent beam line section can be separated. In addition, we can combine the effects of multiple coulomb scattering and transverse energy gradient together in the beam matrix and analyze their net effect. We find that,when applied to an

  18. Variation in taper surface roughness for a single design effects the wear rate in total hip arthroplasty.

    PubMed

    Whittaker, Robert K; Hothi, Harry S; Eskelinen, Antti; Blunn, Gordon W; Skinner, John A; Hart, Alister J

    2017-08-01

    Material loss from the head-stem taper junction of total hip arthroplasty (THA) is implicated in adverse reactions to metal debris (ARMD); the mechanisms for this are multi-factorial. We investigated the relationship between the roughness of the "as manufactured" taper surface and the wear rate from this junction. Fifty retrieved Pinnacle metal-on-metal (MOM) bearings paired with a Corail stem were included in the study. Multivariable statistical analysis was performed to determine the influence of taper roughness on material loss rate after controlling for other confounding surgical, implant, and patient factors. The surface roughness of the "as manufactured" head taper surface was associated with the rate of material loss from this surface. Four of eighteen roughness variables taken from ISO 4,287 and ISO 13,565-2 were significant: The Reduced Peak Height (Rpk, the protruding peaks above the core) (p = 0.004), Material Ratio 1 (Mr1, the ratio of the protruding peaks above the core) (p = 0.002), Area of the Peak Region (A1, the area of the Abbott-Curve that contains the peaks from the profile) (p = 0.003) and the Skewness (Rsk, the asymmetry of the height distribution corresponding to the height or depth of surface features) (p = 0.03). We found a large variability in the measured values with a median (range) of 0.50 (0.05-2.98), 11.98 (0.46-39.98), 30.89 (0.15-581.00), and 0.04 (-0.73-0.84), respectively. A 1-unit increase in Rpk was associated with a 73% increase in the taper wear rate. The variability of "as manufactured" surface roughness has a significant effect on taper material loss. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1784-1792, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  19. Sidestream condensate polishing for PWRs

    SciTech Connect

    Shor, S.W.W.; Yim, S.L.; Rios, J.; Liu, J.

    1986-06-01

    Condensate polishers are used in power plant condensate system to remove both particulate matter and ionized corrodents. Their conventional location is just downstream of the hotwell pumps (condensate pumps). Most polisher installations have enough flow capacity to polish 100% of the condensate. This inline configuration has some disadvantage, including a flow that varies with unit load and tends to disturb the polisher beds and reduce their effectiveness, and a potential for interrupting flow to the feedwater pumps. An alternate arrangement where water is extracted from either the condenser or the condensate system, polished and returned to the system, has been used in a few plants. Three different ways of doing this have been used: divide the condenser hotwell into two parts, one of which receives condensate from the tube bundles and the other of which is sheltered. Take unpolished condensate from the first part, purify it and return it to the other part from which the condensate pumps take suction; take unpolished condensate from one end of a divided header on the suction side of the hotwell pumps and after polishing it return it to the other end; and take unpolished condensate from a header on the discharge side of the condensate pumps, purify it and return it to the condensate system a short distance downstream. The three variants are analyzed in this report. It is concluded that the variant where the connections are on the discharge side of the condensate pumps is the most desirable for retrofitting, in all cases being far easier to retrofit than an inline polisher. In many cases it will be most desirable for new construction.

  20. Spatially resolved spectroscopy using tapered stripline NMR

    NASA Astrophysics Data System (ADS)

    Tijssen, Koen C. H.; Bart, Jacob; Tiggelaar, Roald M.; Janssen, J. W. G. (Hans); Kentgens, Arno P. M.; van Bentum, P. Jan M.

    2016-02-01

    Magnetic field B0 gradients are essential in modern Nuclear Magnetic Resonance spectroscopy and imaging. Although RF/B1 gradients can be used to fulfill a similar role, this is not used in common practice because of practical limitations in the design of B1 gradient coils. Here we present a new method to create B1 gradients using stripline RF coils. The conductor-width of a stripline NMR chip and the strength of its radiofrequency field are correlated, so a stripline chip can be tapered to produce any arbitrary shaped B1 field gradient. Here we show the characterization of this tapered stripline configuration and demonstrate three applications: magnetic resonance imaging on samples with nL-μL volumes, reaction monitoring of fast chemical reactions (10-2-101 s) and the compensation of B0 field gradients to obtain high-resolution spectra in inhomogeneous magnetic fields.

  1. Tapered splice technique for capillary optical fiber

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoliang; Xiang, Huoxing

    2017-07-01

    We propose a simple but effective technique. It is concerned with a tapered splice technique for capillary optical fiber. In order to contrast, we investigate two kinds of capillary optical fiber. One of the capillary optical fiber has the annular core around the air hole and the other one has the embedded annular core around the inner cladding. We demonstrate the tapered splice technique works for both of the capillary optical fiber in experiment. It is the key to improve the coupling efficiency of the capillary optical fiber. We also build a theoretical model to predict the optical power of the capillary optical fiber and it is confirmed by the experimental results. The method provides an insight of the mode conversion characteristics of capillary optical fiber. It should be used as an easy way to realize the fiber-based in-line components and should be more importantly to explore new possibilities with this kind of fiber.

  2. Orthogonal feeding techniques for tapered slot antennas

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Simons, Rainee N.

    1998-01-01

    For array of "brick" configuration there are electrical and mechanical advantages to feed the antenna with a feed on a substrate perpendicular to the antenna substrate. Different techniques have been proposed for exciting patch antennas using such a feed structure.Rncently, an aperture-coupled dielectric resonator antenna using a perpendicular feed substrate has been demonstrated to have very good power coupling efficiency. For a two-dimensional rectangular array with tapered slot antenna elements, a power combining network on perpendicular substrate is generally required to couple power to or from the array. In this paper, we will describe two aperture-coupled techniques for coupling microwave power from a linearly tapered slot antenna (LTSA) to a microstrip feed on a perpendicular substrate. In addition, we will present measured results for return losses and radiation patterns.

  3. Performance of an elliptically tapered neutron guide

    NASA Astrophysics Data System (ADS)

    Mühlbauer, Sebastian; Stadlbauer, Martin; Böni, Peter; Schanzer, Christan; Stahn, Jochen; Filges, Uwe

    2006-11-01

    Supermirror coated neutron guides are used at all modern neutron sources for transporting neutrons over large distances. In order to reduce the transmission losses due to multiple internal reflection of neutrons, ballistic neutron guides with linear tapering have been proposed and realized. However, these systems suffer from an inhomogeneous illumination of the sample. Moreover, the flux decreases significantly with increasing distance from the exit of the neutron guide. We propose using elliptically tapered guides that provide a more homogeneous phase space at the sample position as well as a focusing at the sample. Moreover, the design of the guide system is simplified because ellipses are simply defined by their long and short axes. In order to prove the concept we have manufactured a doubly focusing guide and investigated its properties with neutrons. The experiments show that the predicted gains using the program package McStas are realized. We discuss several applications of elliptic guides in various fields of neutron physics.

  4. Cooling arrangement for a tapered turbine blade

    SciTech Connect

    Liang, George

    2010-07-27

    A cooling arrangement (11) for a highly tapered gas turbine blade (10). The cooling arrangement (11) includes a pair of parallel triple-pass serpentine cooling circuits (80,82) formed in an inner radial portion (50) of the blade, and a respective pair of single radial channel cooling circuits (84,86) formed in an outer radial portion (52) of the blade (10), with each single radial channel receiving the cooling fluid discharged from a respective one of the triple-pass serpentine cooling circuit. The cooling arrangement advantageously provides a higher degree of cooling to the most highly stressed radially inner portion of the blade, while providing a lower degree of cooling to the less highly stressed radially outer portion of the blade. The cooling arrangement can be implemented with known casting techniques, thereby facilitating its use on highly tapered, highly twisted Row 4 industrial gas turbine blades that could not be cooled with prior art cooling arrangements.

  5. Performance of a tapered pulse tube

    SciTech Connect

    Swift, G.; Allen, M.; Woolan, J.J.

    1998-02-01

    In a well instrumented pulse tube refrigerator having 1,500 W of cooling power at 125 K, the authors have measured the figure of merit of a tapered pulse tube at several operating points. At operating points near the operating point for which the taper was designed, the figure of merit is 0.96. This is close to the theoretical optimum figure of merit 0.97 calculated for this pulse tube considering only two loss mechanisms: heat conduction in the metal pulse tube wall and ordinary thermoacoustic heat transport in the gas within a few thermal penetration depths of the wall. At operating points farther from the design operating point, the measured figure of merit is much lower, as streaming driven convection adds a third loss mechanism.

  6. Experimental stiffness of tapered bore seals

    NASA Technical Reports Server (NTRS)

    Fleming, D. P.

    1985-01-01

    The stiffness of tapered-bore ring seals was measured with air as the sealed fluid. Static stiffness agreed fairly well with results of a previous analysis. Cross-coupled stiffness due to shaft rotation was much less than predicted. It is suggested that part of the disparity may be due to simplifying assumptions in the analysis; however, these do not appear to account for the entire difference observed.

  7. Tapered pulse tube for pulse tube refrigerators

    DOEpatents

    Swift, Gregory W.; Olson, Jeffrey R.

    1999-01-01

    Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.

  8. Pump and Signal Taper for Airclad Fibers

    DTIC Science & Technology

    2006-01-05

    as follows: Crystal Fibre A/S will develop a taper/coupler solution to interface between a new polarization maintaining/polarizing amplifier fiber ...MM) pump combiner with a high NA air-clad output. The input side of the combiner is 7 individual MM pump delivery solid all- glass fibers . The NA of...pump combiner. MOTIVATION FINAL REPORT ITEM 0002 In a typical standard fused fiber coupler a number of all- glass 0.22 NA pump

  9. Waveguide taper engineering using coordinate transformation technology

    NASA Astrophysics Data System (ADS)

    Tichit, Paul-Henri; Burokur, Shah Nawaz; de Lustrac, André

    2010-01-01

    Spatial coordinate transformation is a suitable tool for the design of complex electromagnetic structures. In this paper, we define three spatial coordinate transformations which show the possibility of designing a taper between two different waveguides. A parametric study is presented for the three transformations and we propose achievable values of permittivity and permeability that can be obtained with existing metamaterials. The performances of such defined structures are demonstrated by finite element numerical simulations.

  10. Waveguide taper engineering using coordinate transformation technology.

    PubMed

    Tichit, Paul-Henri; Burokur, Shah Nawaz; de Lustrac, André

    2010-01-18

    Spatial coordinate transformation is a suitable tool for the design of complex electromagnetic structures. In this paper, we define three spatial coordinate transformations which show the possibility of designing a taper between two different waveguides. A parametric study is presented for the three transformations and we propose achievable values of permittivity and permeability that can be obtained with existing metamaterials. The performances of such defined structures are demonstrated by finite element numerical simulations.

  11. Design of Structurally Efficient Tapered Struts

    NASA Technical Reports Server (NTRS)

    Messinger, Ross

    2010-01-01

    This report describes the analytical study of two full-scale tapered composite struts. The analytical study resulted in the design of two structurally efficient carbon/epoxy struts in accordance with NASA-specified geometries and loading conditions. Detailed stress analysis was performed of the insert, end fitting, and strut body to obtain an optimized weight with positive margins. Two demonstration struts were fabricated based on a well-established design from a previous Space Shuttle strut development program.

  12. Nanostructured tapered optical fibers for paticle trapping

    NASA Astrophysics Data System (ADS)

    Daly, Mark; Truong, Viet Giang; Nic Chormaic, Síle

    2015-05-01

    Optical micro- and nanofibers have recently gained popularity as tools in quantum engineering using laser-cooled, neutral atoms. In particular, atoms can be trapped around such optical fibers, and photons coupled into the fibers from the surrounding atoms could be used to transfer quantum state information within the system. It has also been demonstrated that such fibers can be used to manipulate and trap silica and polystyrene particles in the 1-3 μm range. We recently proposed using a focused ion beam nanostructured tapered optical fiber for improved atom trapping geometries1. Here, we present details on the design and fabrication of these nanostructured optical fibers and their integration into particle trapping platforms for the demonstration of submicron particle trapping. The optical fibers are tapered to approximately 1-2 μm waist diameters, using a custom-built, heat-and-pull fiber rig, prior to processing using a focused ion beam. Slots of about 300 nm in width and 10-20 μm in length are milled right though the waist regions of the tapered optical fibers. Details on the fabrication steeps necessary to ensure high optical transmission though the fiber post processing are included. Fiber transmissions of over 80% over a broad range of wavelengths, in the 700-11100 nm range, are attainable. We also present simulation results on the impact of varying the slot parameters on the trap depths achievable and milling multiple traps within a single tapered fiber. This work demonstrates even further the functionality of optical micro- and nanofibers as trapping devices across a range of regimes.

  13. Surgical Outcomes of Forearm Loop Arteriovenous Fistula Formation Using Tapered versus Non-Tapered Polytetrafluoroethylene Grafts

    PubMed Central

    Han, Sun; Seo, Pil Won; Ryu, Jae-Wook

    2017-01-01

    Background Tapered grafts, which have a smaller diameter on the arterial side, have been increasingly used for arteriovenous fistula (AVF) formation. We compared the outcomes of 4–6-mm tapered and 6-mm straight forearm loop arteriovenous grafts. Methods A total of 103 patients receiving forearm loop arteriovenous grafts between March 2005 and March 2015 were retrospectively analyzed and separated into 2 groups (group A, 4- to 6-mm tapered grafts, n=78; group B, 6-mm straight grafts, n=25). In each group, complications and patency rates after surgery were assessed. Results Clinical characteristics and laboratory results, except for cerebrovascular disease history (group A, 7.7%; group B, 28.0%; p=0.014), were similar between the groups. No significant differences were found for individual complications. Kaplan-Meier survival analysis revealed no significant differences in 1-year, 3-year, and 5-year patency rates between groups (61.8%, 44.9%, and 38.5% vs. 62.7%, 41.1%, and 35.3%, respectively). Conclusion We found no significant differences in complication and patency rates between the tapered and straight graft groups. If there are no differences in complication and patency between the two graft types, tapered grafts may be a valuable option for AVF formation in light of their other advantages. PMID:28180100

  14. Sensing roughness and polish direction

    NASA Astrophysics Data System (ADS)

    Jakobsen, M. L.; Olesen, A. S.; Larsen, H. E.; Stubager, J.; Hanson, S. G.; Pedersen, T. F.; Pedersen, H. C.

    2016-04-01

    As a part of the work carried out on a project supported by the Danish council for technology and innovation, we have investigated the option of smoothing standard CNC machined surfaces. In the process of constructing optical prototypes, involving custom-designed optics, the development cost and time consumption can become relatively large numbers in a research budget. Machining the optical surfaces directly is expensive and time consuming. Alternatively, a more standardized and cheaper machining method can be used, but then the object needs to be manually polished. During the polishing process the operator needs information about the RMS-value of the surface roughness and the current direction of the scratches introduces by the polishing process. The RMS-value indicates to the operator how far he is from the final finish, and the scratch orientation is often specified by the customer in order to avoid complications during the casting process. In this work we present a method for measuring the RMS-values of the surface roughness while simultaneously determining the polishing direction. We are mainly interested in the RMS-values in the range from 0 - 100 nm, which corresponds to the finish categories of A1, A2 and A3. Based on simple intensity measurements we estimates the RMS-value of the surface roughness, and by using a sectioned annual photo-detector to collect the scattered light we can determine the direction of polishing and distinguish light scattered from random structures and light scattered from scratches.

  15. Efficient polishing of aspheric optics

    SciTech Connect

    Taylor, J.S.; Piscotty, M.A.; Nguyen, N.Q.; Landram, C.S.; Ng, L.C.

    1997-04-15

    The objectives of this project are to develop, evaluate, and optimize novel designs for a polishing tool intended for ultra-precise figure corrections on aspheric optics with tolerances typical of those required for use in extreme ultraviolet (EUV) projection lithography. This work may lead to an enhanced US industrial capability for producing optics for EUV, x-ray and, other high precision applications. LLNL benefits from developments in computer-controlled polishing and the insertion of fluid mechanics modeling into the precision manufacturing area. Our accomplishments include the numerical estimation of the hydrodynamic shear stress distribution for a new polishing tool that directs and controls the interaction of an abrasive slurry with an optical surface. A key milestone is in establishing a correlation between the shear stress predicted using our fluid mechanics model and the observed removal footprint created by a prototype tool. In addition, we demonstrate the ability to remove 25 nm layers of optical glass in a manner qualitatively similar to macroscopic milling operations using a numerically- controlled machine tool. Other accomplishments include the development of computer control software for directing the polishing tool and the construction of a polishing testbed.

  16. Taper Angle Evolution in Taiwan Accretionary Wedge

    NASA Astrophysics Data System (ADS)

    Chen, L.; Chi, W.; Liu, C.

    2011-12-01

    Liwen Chena,b, Wu-Cheng Chia, Char-Shine Liuc aInstitute of Earth Sciences, Academia Sinica, Taipei, Taiwan bInstitute of Geosciences, National Taiwan University, Taipei, Taiwan cInstitute of Oceanography, National Taiwan University, Taipei, Taiwan The critical taper model, originally developed using onland Taiwan as an example, is governed by force balance of a horizontal compressional wedge. This model has been successfully applied to many mountainous regions around the world. Among them, Taiwan is located in an oblique collision between the Luzon Arc and the Chinese Passive margin. Previous critical taper angle studies of Taiwan are mainly focusing on utilizing land data. In this study we want to extend these studies to offshore region from the subduction zone to collision zone. Here we study the varying taper angles of the double-vergent wedge derived from 1,000 km of reflection seismic profiles in both the pro-wedge and retro-wedge locations. These profiles were collected in the last two decades. For the retro-wedge, the topography slope angle changes from 2 to 8.8 degrees; some of the steep slope suggests that some part of the retrowedge is currently in a super-critical angle state. Such dramatic changes in taper angle probably strongly affect regional sedimentary processes, including slumping, in addition to structural deformation. These complex processes might even help develop a mélange or re-open a closed basin. We are currently working on studying the taper angle evolution of the pro-wedge from subduction to arc-continent collision zone in the offshore region. Though further works are needed, our preliminary results show that the evolution of wedge angles and the geometry of the wedge are closely linked and inseparable. The structures of the subducting plate might have strong influence on the deformation style of the over-riding plate. It would be interesting to combine the angle variation with the structure interpretation of the accretionary wedge

  17. Polishing of dental porcelain by polycrystalline diamond.

    PubMed

    Nakamura, Yoshiharu; Sato, Hideaki; Ohtsuka, Masaki; Hojo, Satoru

    2010-01-01

    Polycrystalline diamond (PCD) exhibits excellent abrasive characteristics and is commonly used as loose grains for precision machining of hard ceramics and other materials that are difficult to grind and polish. In the present study, we investigated using bonded PCD for polishing dental porcelain, for which a lustrous surface is difficult to obtain by polishing. We compared the surface texture and characteristics of dental porcelain after polishing with bonded PCD with that obtained using bonded monocrystalline diamond (MCD), which is commonly used for this purpose. Polishing was performed at various pressures and rotational speeds on a custom-built polishing apparatus using bonded PCD or MCD with grain sizes of 3.92 μm on specimens consisting of VITA Omega 900 dentin porcelain after firing and then glazing to a specified surface roughness. The surface roughness of the polished porcelain and the abrasion quantity in terms of its polishing depth were measured, and its surface texture and characteristics were investigated. At low polishing pressures, PCD yielded a finer polished surface than MCD. The polishing depth after polishing for 20-30 min was approximately 2-3 μm with PCD and 1-2 μm with MCD. The polished surface was more uniform and smooth with PCD than with MCD.

  18. Natural polish in granitic rocks

    NASA Astrophysics Data System (ADS)

    Siman-Tov, S.; Brodsky, E. E.; Stock, G. M.; White, J. C.

    2016-12-01

    Fault mirrors are highly smooth and reflective rock surfaces that are found in many shear zones around the world. Recent studies suggest that fault mirrors are formed during high velocity slip on faults and therefore may serve as an indicator for seismic slip. In contrast, other studies suggest that fault mirrors may form under high normal stress at sub-seismic velocities and at room temperature. Fault mirrors are observed within the fault core of many rock type environments including limestone, dolomite, chert and rhyolite. However, to the best of our knowledge, they are missing in faults hosted in granite. Moreover, mirror-like surfaces form during high velocity rotary shear experiments in many types of rock but not in sheared granite blocks. The absence of fault mirrors in granite is surprising, particularly since there exists extensive glacial polish on granitic bedrock. Glacial polish describes the smooth and reflective rock surfaces formed at the base of glaciers that carved the underlying bedrock. In addition to their import for studies of glacial dynamics and geomorphology, glacially polished surfaces may hold some significance for fault mechanics. Glacial polish and fault mirrors share many similarities. At field exposures they both present highly smooth surfaces and striations that clearly point in the slip direction. Studies on carbonate fault mirrors showed that individual highly reflective surfaces are composed of a thin nanograin layer. Preliminary SEM observations on samples collected from granitic rocks at Yosemite National Park suggest that these polished surfaces are also coated by an ultrathin cohesive layer composed of nanograins. Although there are clear differences between glacial and fault-zone environments, the similarity between these textures, and the fact that both are formed during shear, suggest that a similar mechanism is responsible for their formation. The comparison raises questions about the importance of high fluid contents and

  19. Graphite Composite Panel Polishing Fixture

    NASA Technical Reports Server (NTRS)

    Hagopian, John; Strojny, Carl; Budinoff, Jason

    2011-01-01

    The use of high-strength, lightweight composites for the fixture is the novel feature of this innovation. The main advantage is the light weight and high stiffness-to-mass ratio relative to aluminum. Meter-class optics require support during the grinding/polishing process with large tools. The use of aluminum as a polishing fixture is standard, with pitch providing a compliant layer to allow support without deformation. Unfortunately, with meter-scale optics, a meter-scale fixture weighs over 120 lb (.55 kg) and may distort the optics being fabricated by loading the mirror and/or tool used in fabrication. The use of composite structures that are lightweight yet stiff allows standard techniques to be used while providing for a decrease in fixture weight by almost 70 percent. Mounts classically used to support large mirrors during fabrication are especially heavy and difficult to handle. The mount must be especially stiff to avoid deformation during the optical fabrication process, where a very large and heavy lap often can distort the mount and optic being fabricated. If the optic is placed on top of the lapping tool, the weight of the optic and the fixture can distort the lap. Fixtures to support the mirror during fabrication are often very large plates of aluminum, often 2 in. (.5 cm) or more in thickness and weight upwards of 150 lb (68 kg). With the addition of a backing material such as pitch and the mirror itself, the assembly can often weigh over 250 lb (.113 kg) for a meter-class optic. This innovation is the use of a lightweight graphite panel with an aluminum honeycomb core for use as the polishing fixture. These materials have been used in the aerospace industry as structural members due to their light weight and high stiffness. The grinding polishing fixture consists of the graphite composite panel, fittings, and fixtures to allow interface to the polishing machine, and introduction of pitch buttons to support the optic under fabrication. In its

  20. Polishing compound for plastic surfaces

    SciTech Connect

    Stowell, Michael S.

    1995-01-01

    A polishing compound for plastic surfaces. The compound contains by weight approximately 4 to 17 parts at least one petroleum distillate lubricant, 1 to 6 parts mineral spirits, 2.5 to 15 parts abrasive particles, and 2.5 to 10 parts water. The abrasive is tripoli or a similar material that contains fine particles silica. Preferably, most of the abrasive particles are less than approximately 10 microns, more preferably less than approximately 5 microns in size. The compound is used on PLEXIGLAS.TM., LEXAN.TM., LUCITE.TM., polyvinyl chloride (PVC) and similar plastic materials whenever a smooth, clear polished surface is desired.

  1. Polishing compound for plastic surfaces

    DOEpatents

    Stowell, M.S.

    1993-01-01

    A polishing compound for plastic surfaces is disclosed. The compound contains by weight approximately 4 to 17 parts at least one petroleum distillate lubricant, 1 to 6 parts mineral spirits, 2.5 to 15 parts abrasive particles, and 2.5 to 10 parts water. The abrasive is tripoli or a similar material that contains colloidal silica. Preferably, most of the abrasive particles are less than approximately 10 microns, more preferably less than approximately 5 microns in size. The compound is used on PLEXIGLAS{sup TM}, LEXAN{sup TM}, LUCITE{sup TM}, polyvinyl chloride (PVC) and similar plastic materials whenever a smooth, clear polished surface is desired.

  2. Polishing compound for plastic surfaces

    DOEpatents

    Stowell, M.S.

    1995-08-22

    A polishing compound for plastic surfaces is disclosed. The compound contains by weight approximately 4 to 17 parts at least one petroleum distillate lubricant, 1 to 6 parts mineral spirits, 2.5 to 15 parts abrasive particles, and 2.5 to 10 parts water. The abrasive is tripoli or a similar material that contains fine particles silica. Preferably, most of the abrasive particles are less than approximately 10 microns, more preferably less than approximately 5 microns in size. The compound is used on PLEXIGLAS{trademark}, LEXAN{trademark}, LUCITE{trademark}, polyvinyl chloride (PVC) and similar plastic materials whenever a smooth, clear polished surface is desired. 5 figs.

  3. Effects of taper on swim performance. Practical implications.

    PubMed

    Houmard, J A; Johns, R A

    1994-04-01

    Competitive swimmers commonly focus upon optimising performance at a single competition. A period where training volume is incrementally reduced or "tapered" often precedes such a competition. The use of taper is justified as increases in muscular power, and the restoration of plasma haematocrit, haemoglobin and creatine kinase are evident with this training reduction. A consistent performance improvement of approximately 3% has also been reported with taper in competitive swimmers. However, there are limitations in terms of what comprises a successful taper schedule. It appears that a taper which improves performance involves a substantial (60 to 90%) graded reduction in training volume, and daily high intensity interval work over a 7- to 21-day period. Training frequency should be reduced by no more than 50%; a more conservative estimate would be to reduce frequency by approximately 20%. Optimal performance is likely when the reduction in training frequency is combined with the qualitative knowledge of the coach and/or athlete during taper.

  4. Continuous distal migration and internal rotation of the C-stem prosthesis without any adverse clinical effects: an RSA study of 33 primary total hip arthroplasties followed for up to ten years.

    PubMed

    von Schewelov, T; Carlsson, A; Sanzén, L; Besjakov, J

    2014-05-01

    In 2005, we demonstrated that the polished triple-tapered C-stem at two years had migrated distally and rotated internally. From that series, 33 patients have now been followed radiologically, clinically and by radiostereometric analysis (RSA) for up to ten years. The distal migration within the cement mantle had continued and reached a mean of 2 mm (0.5 to 4.0) at ten years. Internal rotation, also within the cement mantle, was a mean 3.8° (external 1.6° to internal 6.6°) The cement mantle did not show any sign of migration or loosening in relation to the femoral bone. There were no clinical or radiological signs indicating that the migration or rotation within the cement mantle had had any adverse effects for the patients.

  5. Tapering practices of Croatian open-class powerlifting champions.

    PubMed

    Grgic, Jozo; Mikulic, Pavle

    2016-10-27

    The aim of this study was to explore tapering practices among 10 Croatian open-class powerlifting champions (mean ± SD: age 29.2 ± 3.2 years; Wilks coefficient 355.1 ± 54.8). The athletes were interviewed about their tapering practices using a semi-structured interview, after which the audio content was transcribed. The athletes reported decreasing training volume during the taper by 50.5 ± 11.7% using a step type or an exponential type of taper with a fast decay. Training intensity was maintained or increased during the taper, and it reached its highest values 8 ± 3 days before the competition. Training frequency was reduced or maintained during the taper. The final week included a reduction in training frequency by 47.9 ± 17.5% with the last training session performed 3 ± 1 days before the competition. The participants typically stated that the main reasons for conducting the taper were maintaining strength and reducing the amount of fatigue. They also stated that (a) the taper was structured identically for the squat, bench press, and the deadlift; (b) the training during the taper was highly specific, the assistance exercises were removed, and the same equipment was used as during competition; (c) the source of information for tapering was their coach, and training fluctuated based on the coach's feedback; and (d) nutrition, foam rolling, static stretching, and massage were all given extra attention during the taper. These results may aid athletes and coaches in strength sports in terms of the optimization of tapering variables.

  6. Phase Centers of Subapertures in a Tapered Aperture Array.

    SciTech Connect

    Doerry, Armin W.; Bickel, Douglas L.

    2015-11-01

    Antenna apertures that are tapered for sidelobe control can also be parsed into subapertures for Direction of Arrival (DOA) measurements. However, the aperture tapering complicates phase center location for the subapertures, knowledge of which is critical for proper DOA calculation. In addition, tapering affects subaperture gains, making gain dependent on subaperture position. Techniques are presented to calculate subaperture phase center locations, and algorithms are given for equalizing subapertures’ gains. Sidelobe characteristics and mitigation are also discussed.

  7. Migration and strains induced by different designs of force-closed stems for THA☆

    PubMed Central

    Griza, Sandro; Gomes, Luiz Sérgio Marcelino; Cervieri, André; Strohaecker, Telmo Roberto

    2015-01-01

    Objectives Subtle differences in stem design can result in different mechanical responses of the total hip arthroplasty. Tests measuring migration of the stem relative to the femur, as well as the strains in the cement mantle and on the femur can detect different mechanical behavior between stems. Methods In this article, conical, double and triple tapered stems were implanted in composite femurs and subjected to static and cyclic loads. Stems differed mainly on taper angle, calcar radius and proximal stiffness. Stem migration and strains on the femur and in the cement mantle were achieved. Results Significant differences (p < 0.05) were noted in the permanent rotation between double and triple tapers, in the strains on the proximal medial femur between triple and both conical and double tapers, and in the strains on the lateral proximal femur between double tapers and both conical and triple tapers. Conclusion The proposed mechanical tests were able to detect significant differences in the behavior of these resembling stems. Stem proximal stiffness and the calcar radius of the stem influence its rotational stability and the strain transmission to the femur. PMID:27218081

  8. The Polish People: The Challenge of Sponsorship.

    ERIC Educational Resources Information Center

    Li, Gertraude Roth; Johnson, Winston

    This report provides background information on Polish refugees that may be of use to sponsors involved in Polish refugee resettlement in the United States. The report discusses economic and social conditions in Poland; the social values and political attitudes of modern Polish refugees as opposed to those of Poles who settled in the United States…

  9. The Polish People: The Challenge of Sponsorship.

    ERIC Educational Resources Information Center

    Li, Gertraude Roth; Johnson, Winston

    This report provides background information on Polish refugees that may be of use to sponsors involved in Polish refugee resettlement in the United States. The report discusses economic and social conditions in Poland; the social values and political attitudes of modern Polish refugees as opposed to those of Poles who settled in the United States…

  10. Proceedings: 2002 Workshop on Condensate Polishing

    SciTech Connect

    2002-06-01

    Condensate polishing aims to control impurities in a nuclear power plant, thus allowing the unit to operate more reliably. This report contains the work presented at EPRI's 2002 Workshop on Condensate Polishing, where 36 papers were presented on current issues, research, and utility experiences involving polishing issues at both pressurized water reactor (PWR) and boiling water reactor (BWR) units.

  11. Proceedings: 2000 Workshop on Condensate Polishing

    SciTech Connect

    2001-06-01

    Condensate polishing maintains control of impurities in the nuclear power plant and allows the unit to operate more reliably. This report presents proceedings of EPRI's 2000 Workshop on Condensate Polishing, where 30 papers were presented on current issues and utility experience involving condensate polishing at both pressurized water reactor (PWR) and boiling water reactor (BWR) plants.

  12. Radiation pattern analysis of the tapered slot antenna, appendix 1

    NASA Technical Reports Server (NTRS)

    Janaswamy, Ramakrishna

    1986-01-01

    A theoretical model for the tapered slot antenna is presented. The model is valid for any smooth taper of the slot. The problem is solved by modeling the slot electric field and using the half plane Green's function to compute the far fields. The aperture field is obtained by affecting a stepped approximation to the continuous taper and utilizing the uniform wide slot line data. The uniform wide slot line is solved by the spectral Galerkin's technique and closed form experssions are developed for the slot wave length and the slot characteristic impedance. Numerous comparisons with measurement are made to demonstrate the versatility of the model in treating an arbitrary slot taper.

  13. Polarization-maintaining property of tapered polarization-maintaining fibers.

    PubMed

    Wang, Xiaozhen; Niedermayer, Graeme; Lin, Ganbin; Lu, Ping; Wang, Baishi; Chen, Liang; Bao, Xiaoyi

    2013-03-10

    Distributed group birefringence of tapered polarization-maintaining fibers (PMFs) is measured by employing a high-resolution optical frequency-domain reflectometry system. Autocorrelation data processing reveals distributed mode coupling between the fast and slow modes and higher-order modes excited by the tapering process along the taper region. The polarization-maintaining property of a tapered PMF is examined by distributed group birefringence along the tapered PMF with a spatial resolution of ~1.25 cm and a polarization-extinction ratio at the fiber taper output over the wavelength range of 1510-1570 nm. With a waist diameter of 80 μm, the polarization state of the launched light is maintained and the birefringence of the tapered PMF is slightly reduced from 3.28×10(-4) to 2.89×10(-4) at the taper waist. For both the waist diameters of 60 and 40 μm, mode coupling is observed in the form of significantly decreased birefringence by a factor of ~10 at the taper waists.

  14. Low-crosstalk Si arrayed waveguide grating with parabolic tapers.

    PubMed

    Ye, Tong; Fu, Yunfei; Qiao, Lei; Chu, Tao

    2014-12-29

    A silicon arrayed waveguide grating (AWG) with low channel crosstalk was demonstrated by using ultra-short parabolic tapers to connect the AWG's free propagation regions and single-mode waveguides. The tapers satisfied the requirements of low-loss mode conversion and lower channel crosstalk from the coupling of neighboring waveguides in the AWGs. In this work, three different tapers, including parabolic tapers, linear tapers, and exponential tapers, were theoretically analyzed and experimentally investigated for a comparison of their effects when implemented in AWGs. The experimental results showed that the AWG with parabolic tapers had a crosstalk improvement up to 7.1 dB compared with the others. Based on the advantages of parabolic tapers, a 400-GHz 8 × 8 cyclic AWG with 2.4 dB on-chip loss and -17.6~-25.1 dB crosstalk was fabricated using a simple one-step etching process. Its performance was comparable with that of existing AWGs with bi-level tapers, which require complicated two-step etching fabrication processes.

  15. Reading Authentic Polish, Volume I.

    ERIC Educational Resources Information Center

    Walczynski, Waldemar

    This book of instructional materials for reading in Polish are intended for college-level students, and are designed to bring native English-speakers from an 0+ (Novice High) to a 1+ (Intermediate High) language proficiency level on the American Council on the Teaching of Foreign Languages/Interagency Language Roundtable proficiency scale. The…

  16. Reading Authentic Polish, Volume I.

    ERIC Educational Resources Information Center

    Walczynski, Waldemar

    This book of instructional materials for reading in Polish are intended for college-level students, and are designed to bring native English-speakers from an 0+ (Novice High) to a 1+ (Intermediate High) language proficiency level on the American Council on the Teaching of Foreign Languages/Interagency Language Roundtable proficiency scale. The…

  17. A tapered box model of the cochlea

    NASA Astrophysics Data System (ADS)

    Sun, Luyang; Ni, Guangjian; Elliott, Stephen

    2015-12-01

    The complicated, three dimensional geometry of the fluid chambers in the cochlea is often represented in models of its mechanics by a box with a uniform area along its length. In this paper we use previous measurements of the variation in area of the two fluid chambers along the length of the cochlea in various mammals, to calculate the variation in the "effective area" that determines the 1D fluid coupling, which is given by the harmonic mean of the two chamber areas. The square root of this effective area is found to vary surprisingly linearly along the cochlea length in several mammalian species. This suggests a variation of the box model in which the width and height of the two fluid chambers are still equal, but now decrease linearly along its length. The width of the basilar membrane, BM, is assumed to increase linearly along the length of the model. The analytic form of the 1D fluid pressure distribution due to elemental BM motion is derived for this tapered box model. The added mass due to the near field acoustic coupling can also be computed, which surprisingly turns out to be almost constant along the length of the BM. The coupled response of the box model with a passive BM can then be readily calculated. Although the pressure distributions due to elemental fluid coupling are very different in the uniform and tapered box models, the distribution of the passive BM response in the coupled models are very similar in the two cases, although the overall level of the response in the tapered model is about 10 dB greater than that in the uniform model.

  18. Fiber taper coupling to chalcogenide microsphere modes

    SciTech Connect

    Grillet, Christian; Bian Shuning; Magi, Eric C.; Eggleton, Benjamin J.

    2008-04-28

    We report the fabrication and optical characterization of microsphere in chalcogenide (As{sub 2}Se{sub 3}). We show that high Q modes of a 9.2 {mu}m diameter chalcogenide glass can be efficiently excited via evanescent coupling using a silica tapered fiber. Loaded Q factors of more than 20 000 have been measured. Fine analysis of the coupling spectrum around 1619 nm led to an estimation of the microsphere eccentricity of less than 1%. Owing to the unique combination properties of chalcogenide glass and the microspheres geometry, we expect this architecture to offer an ideal environment for versatile applications on both the telecommunication and midinfrared wavelength windows.

  19. Improved Tennis Racquets Have Tapered Strings

    NASA Technical Reports Server (NTRS)

    Noever, David A.

    1995-01-01

    Design concept for better performing tennis racquet. Essence of concept to taper strings in such way as to shift center of percussion (also called "sweet spot") toward the toe (outer end of racquet, farthest from player's hand). In addition to increasing power on serves, also improves player's control and feel of racquet in player's hand. Racquet less likely to twist in player's hand on off-center shots. Important element of better feel is better absorption of vibrations; especially for players having chronic arm problems. String material nylon, animal gut, or other naturally or artifically spun threads. String can be attached to conventional racquet frame.

  20. Resonant plasmon nanofocusing by closed tapered gaps.

    PubMed

    Søndergaard, Thomas; Bozhevolnyi, Sergey I; Beermann, Jonas; Novikov, Sergey M; Devaux, Eloïse; Ebbesen, Thomas W

    2010-01-01

    We study radiation nanofocusing by closed tapered gaps, i.e. metal V-grooves, under normal illumination, and discover that the local field inside a groove can be resonantly enhanced due to interference of counter-propagating gap plasmons. Considering V-grooves milled in gold, we analyze this phenomenon theoretically, deriving an analytic expression for the resonance condition and predicting more than 550-fold intensity enhancements at resonance, and observe it experimentally with two-photon photoluminescence microscopy, demonstrating more than 100-fold intensity enhancements.

  1. Characterization of angled tapered superluminescent LEDs.

    PubMed

    Causa, Federica; Sarma, Jayanta; Yunus, Sharina

    2002-08-20

    We present a detailed analysis of the output beam of high-power edge-emitting angled tapered superluminescent LEDs (A-TSLEDs). A device model, including spontaneous and stimulated emission processes as well as the typical nonuniform carrier-density distribution due to current spreading and carrier diffusion, has been developed and used to interpret the experimentally obtained characteristics of inhouse-fabricated A-TSLEDs. The good match between measured and theoretical results indicates that the model reproduces the A-TSLED operation very satisfactorily and clearly explains the role of the collecting lens on the pronounced asymmetry of some of the measured optical intensity profiles.

  2. Window taper functions for subaperture processing.

    SciTech Connect

    Doerry, Armin Walter

    2013-12-01

    It is well known that the spectrum of a signal can be calculated with a Discrete Fourier Transform (DFT), where best resolution is achieved by processing the entire data set. However, in some situations it is advantageous to use a staged approach, where data is first processed within subapertures, and the results are then combined and further processed to a final result. An artifact of this approach is the creation of grating lobes in the final response. The nature of the grating lobes, including their amplitude and spacing, is an artifact of window taper functions, subaperture offsets, and subaperture processing parameters. We assess these factors and exemplify their effects.

  3. Cross-linguistic parallels in processing derivational morphology: evidence from Polish.

    PubMed

    Bozic, Mirjana; Szlachta, Zanna; Marslen-Wilson, William D

    2013-12-01

    Neuroimaging evidence in English suggests that the neurocognitive processing of derivationally complex words primarily reflects their properties as whole forms. The current experiment provides a cross-linguistic examination of these proposals by investigating the processing of derivationally complex words in the rich morphological system of Polish. Within the framework of a dual language system approach, we asked whether there is evidence for decompositional processing of derivationally complex Polish stems - reflected in the activation of a linguistically specific decompositional system in the left hemisphere - or for increased competition between the derived stem and its embedded base stem in the bilateral system. The results showed activation in the bilateral system and no evidence for selective engagement of the left hemisphere decompositional system. This provides a cross-linguistic validation for the hypothesis that the neurocognitive processing of derived stems primarily reflects their properties as stored forms.

  4. The Effect of Impact Location on Force Transmission to the Modular Junctions of Dual-Taper Modular Hip Implants.

    PubMed

    Frisch, Nicholas B; Lynch, Jonathan R; Banglmaier, Richard F; Silverton, Craig D

    2016-09-01

    The purpose of this study was to investigate the effect that off-axis impaction has on stability of dual-taper modular implants as measured by forces delivered to and transmitted through the head-neck and neck-stem tapers, respectively. One hundred forty-four impact tests were performed using 6 different directions: one on-axis and five 10° off-axes. Four different simulations were performed measuring the head-neck only and 3 different neck angulations: 0°, 8°, and 15°. A drop tower impactor delivered both on- and off-axis impaction from a constant height. Load cells positioned in the drop mass and at the head-neck (HN) or neck-stem (NS) junction measured the impact and joint forces, respectively. Impact force of the hammer on the head ranged from 3800-4500 N. Greatest impact force delivered to the head was typically with axial impact. However, greatest force transmission to the neck-stem junction was not necessarily with axial impacts. There was limited variability in the force measured at the NS junction for all impaction directions seen in the 8° neck, whereas the 15° neck had greater forces transmitted to the NS junction with off-axes impactions directed in the proximal and posterior-proximal directions. The location of the impact significantly influences the force transmitted to the head-neck and neck-stem junctions in dual-taper modular hip implants. Although axial impacts proved superior to off-axis impacts for the straight 0° neck, greater force transmission with off-axis impacts for the angled necks suggests that off-axis impacts may potentially compromise the stability of dual-taper components. Published by Elsevier Inc.

  5. Results of a Modular Femoral Revision System Before and After Taper Roller Hardening in Total Hip Arthroplasty.

    PubMed

    Marshall, Dean J; Berend, Keith R; Morris, Michael J; Adams, Joanne B; Lombardi, Adolph V

    2017-07-25

    Modular component options can aid in addressing complex femoral reconstructions in total hip arthroplasty (THA) by allowing for customization of version control and proximal to distal sizing. However, component breakage at the modular junction has occurred, particularly in the presence of poor bone stock. A taper roller hardening (RH) process was developed to strengthen the modular junction to reduce breakage. The purpose of this study is to review THA patients before and after taper roller hardening to compare stem survival and frequency of breakage. A query of our practice registry revealed 183 consented patients (202 THA) who underwent THA with a modular femoral revision component between January 1993 and September 2010. Forty THA were done before (non-RH) and 162 were done after taper roller hardening. Mean follow-up was seven and 17 years in the RH and non-RH groups respectively. In the non-RH group, 15% were revised for component breakage versus 2% in the RH group. Overall, 35% non-RH versus 8% RH stems have been revised. Kaplan-Meier survival at 10 years with endpoint of stem revision for breakage revealed 84.2% ( ±6.0%) non-RH compared with 95.5% ( ±2.2%) RH (p=0.0033), and with endpoint of stem revision for any reason, 65.0% ( ±7.5%) non-RH compared with 80.3% ( ±3.7%) RH (p=0.0022). Results indicate that the taper roller hardening process was successful in improving durability of a modular femoral revision system and reducing frequency of component breakage for patients who require treatment of the deficient femur in complex primary and revision THA.

  6. Variations in the trunnion surface topography between different commercially available hip replacement stems.

    PubMed

    Munir, Selin; Walter, William L; Walsh, William Robert

    2015-01-01

    Modular hip implants allows for the adjustment of leg length, offset, and the ability to remove the head for acetabular exposure during primary and revision surgery. The design of the Morse taper facilitates the intimate contact of the conical trunnion of the femoral stem (male component), with the conical bore of the femoral head (female component). Orthopaedic trunnion tapers are not standardized and vary in length, taper angle, and base dimension. Variations in the design and surface characteristics of the trunnion, will directly reflect on the interface at the taper junction and can influence the likelihood of subsequent wear, corrosion and longevity of the implant. The effect of surface topography of trunnions on commercially available hip stems has not yet been considered as a possible contributing factor in the corrosion observed at taper junctions. In this study we analyzed the surface topography and surface roughness of randomly selected commercially available femoral hip stem trunnions to obtain a greater insight into their surface characteristics.

  7. The violin bow: taper, camber and flexibility.

    PubMed

    Gough, Colin

    2011-12-01

    An analytic, small-deflection, simplified model of the modern violin bow is introduced to describe the bending profiles and related strengths of an initially straight, uniform cross-section, stick as a function of bow hair tension. A number of illustrative bending profiles (cambers) of the bow are considered, which demonstrate the strong dependence of the flexibility of the bow on longitudinal forces across the ends of the bent stick. Such forces are shown to be comparable in strength to critical buckling loads causing excessive sideways buckling unless the stick is very straight. Non-linear, large deformation, finite element computations extend the analysis to bow hair tensions comparable with and above the critical buckling strength of the straight stick. The geometric model assumes an expression for the taper of Tourte bows introduced by Vuillaume, which is re-examined and generalized to describe violin, viola and cello bows. A comparison is made with recently published measurements of the taper and bending profiles of a particularly fine bow by Kittel.

  8. A Volume and Taper Prediction System for Bald Cypress

    Treesearch

    Bernard R. Parresol; James E. Hotvedt; Quang V. Cao

    1987-01-01

    A volume and taper prediction system based on d10 and consisting of a total volume equation, two volume ratio equations (one for diameter limits, the other for height limits), and a taper equation was developed for bald cypress using sample tree data collected in Louisiana. Normal diameter (dn), a subjective variable-...

  9. Maximal mechanical power during a taper in elite swimmers.

    PubMed

    Trinity, Joel D; Pahnke, Matthew D; Reese, Edwin C; Coyle, Edward F

    2006-09-01

    Insight regarding the fluctuations in neuromuscular function among athletes during a taper is lacking. This study examined the time course of changes in maximal mechanical power (Pmax), torque at power maximum (T), velocity at power maximum (V), and swim performance (m x s(-1)) that occur during the taper. Using an arm ergometer with inertial loading, measurements were made during the week prior to the initiation of the taper (high volume, HV), during the 2- to 3-wk period of the taper (taper), and during the week of peak competition (peak) in 24 male competitive collegiate swimmers. Subjects were divided into groups that tapered to peak performance at either the conference (CONF, N = 13) or national (NAT, N = 11) championship competitions. CONF increased Pmax 10.2% (P < 0.01) and swim performance 4.4% (P < 0.001). NAT increased Pmax by 11.6% (P < 0.01), T by 7.4% (P < 0.02), and swim performance by 4.7% (P < 0.001). Pmax displayed a biphasic increase with approximately 50, 5, and 45% of the total increase occurring during the first, second, and third weeks of the taper, respectively. The biphasic response was the most common response among individual swimmers. Swimming performance was significantly correlated to both power and torque (P < 0.05). In summary, maximal arm power measured using inertial load ergometry increased largely during the first and third weeks after training volume was tapered for peak performance in elite collegiate swimmers.

  10. Maximal power and performance during a swim taper.

    PubMed

    Trinity, J D; Pahnke, M D; Sterkel, J A; Coyle, E F

    2008-06-01

    This study examined how altering training intensity during a taper impacts maximal mechanical power (Pmax), torque at power maximum (T), velocity at power maximum (V), and swim performance (m . sec (-1)). Using an arm ergometer with inertial loading, measurements of Pmax, T, and V were made for 7 consecutive weeks prior to the taper and during the taper in 7 female competitive collegiate swimmers. Subjects were tested over two consecutive years. Swim performance was obtained from 3 competitive meets; a conference meet (CM), the conference championship meet (CONF) and the national championship meet (NAT). A 50 to 60 % increase in the amount of "high-intensity training" during the taper of 2005 (High-Intensity Taper - HIT) resulted in Pmax values that were 8 to 14 % higher (40 to 60 Watts) at all but one time point when compared to the 2004 taper (Low-Intensity Taper - LIT). Swim performance was significantly worsened at the NAT following LIT. However, with the HIT, swim performance, Pmax, and T were maintained prior to and at NAT. A large reduction in high-intensity training during a taper reduces the length of time that Pmax, T, and swim performance can be maintained at peak levels.

  11. Electromagnetic field tapering using all-dielectric gradient index materials

    PubMed Central

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-01-01

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes. PMID:27464989

  12. Electromagnetic field tapering using all-dielectric gradient index materials.

    PubMed

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-07-28

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes.

  13. Electromagnetic field tapering using all-dielectric gradient index materials

    NASA Astrophysics Data System (ADS)

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-07-01

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes.

  14. Energy savings in Polish buildings

    SciTech Connect

    Markel, L.C.; Gula, A.; Reeves, G.

    1995-12-31

    A demonstration of low-cost insulation and weatherization techniques was a part of phase 1 of the Krakow Clean Fossil Fuels and Energy Efficient Project. The objectives were to identify a cost-effective set of measures to reduce energy used for space heating, determine how much energy could be saved, and foster widespread implementation of those measures. The demonstration project focused on 4 11-story buildings in a Krakow housing cooperative. Energy savings of over 20% were obtained. Most important, the procedures and materials implemented in the demonstration project have been adapted to Polish conditions and applied to other housing cooperatives, schools, and hospitals. Additional projects are being planned, in Krakow and other cities, under the direction of FEWE-Krakow, the Polish Energie Cities Network, and Biuro Rozwoju Krakowa.

  15. Polishing compound for plastic surfaces

    DOEpatents

    Stowell, M.S.

    1991-01-01

    This invention is comprised of a polishing compound for plastic materials. The compound includes approximately by approximately by weight 25 to 80 parts at least one petroleum distillate lubricant, 1 to 12 parts mineral spirits, 50 to 155 parts abrasive paste, and 15 to 60 parts water. Preferably, the compound includes approximately 37 to 42 parts at least one petroleum distillate lubricant, up to 8 parts mineral spirits, 95 to 110 parts abrasive paste, and 50 to 55 parts water. The proportions of the ingredients are varied in accordance with the particular application. The compound is used on PLEXIGLAS{trademark}, LEXAN{trademark}, LUCITE{trademark}, polyvinyl chloride (PVC), and similar plastic materials whenever a smooth, clear polished surface is desired.

  16. Functional significance of the taper of vertebrate cone photoreceptors

    PubMed Central

    Hárosi, Ferenc I.

    2012-01-01

    Vertebrate photoreceptors are commonly distinguished based on the shape of their outer segments: those of cones taper, whereas the ones from rods do not. The functional advantages of cone taper, a common occurrence in vertebrate retinas, remain elusive. In this study, we investigate this topic using theoretical analyses aimed at revealing structure–function relationships in photoreceptors. Geometrical optics combined with spectrophotometric and morphological data are used to support the analyses and to test predictions. Three functions are considered for correlations between taper and functionality. The first function proposes that outer segment taper serves to compensate for self-screening of the visual pigment contained within. The second function links outer segment taper to compensation for a signal-to-noise ratio decline along the longitudinal dimension. Both functions are supported by the data: real cones taper more than required for these compensatory roles. The third function relates outer segment taper to the optical properties of the inner compartment whereby the primary determinant is the inner segment’s ability to concentrate light via its ellipsoid. In support of this idea, the rod/cone ratios of primarily diurnal animals are predicted based on a principle of equal light flux gathering between photoreceptors. In addition, ellipsoid concentration factor, a measure of ellipsoid ability to concentrate light onto the outer segment, correlates positively with outer segment taper expressed as a ratio of characteristic lengths, where critical taper is the yardstick. Depending on a light-funneling property and the presence of focusing organelles such as oil droplets, cone outer segments can be reduced in size to various degrees. We conclude that outer segment taper is but one component of a miniaturization process that reduces metabolic costs while improving signal detection. Compromise solutions in the various retinas and retinal regions occur between

  17. Comparative study of the variability of 0.06 tapered rotary endodontic files to current taper standards.

    PubMed

    Hatch, Garth W; Roberts, Steven; Joyce, Anthony P; Runner, Royce; McPherson, James C

    2008-04-01

    This study compared the taper variation among Profile, Guidance, and EndoSequence 0.06 tapered rotary files to current standards. Fifteen files of sizes 35, 40, and 45 from each manufacturer were evaluated for a total of 135 files. A digital image of the first 4 mm of each file was captured with light microscope at 22x, calibrated for 0.001-mm accuracy, and analyzed. The diameter of each file was measured at 1 and 4 mm, and the taper was calculated. Of the 3 file systems, 100% of the Profile files, 97.8% of the Guidance files, and 86.7% of the EndoSequence files fell within +/-0.02 taper. All file systems demonstrated variability within their groups. A series of chi(2) analyses indicated that manufacturers tend to produce Guidance and Profile tapers slightly under the ideal 0.06 taper (P < .05). The tapers of EndoSequence files were just as likely to be over or under the advertised 0.06 taper (P > .05).

  18. Mach-Zehnder interferometer based on tapered PCF with an up-tapered joint for curvature, strain and temperature interrogation

    NASA Astrophysics Data System (ADS)

    Narayan Dash, Jitendra; Jha, Rajan

    2016-10-01

    We propose a Mach-Zehnder interferometric sensor based on tapered Photonic Crystal Fiber (PCF) with up-tapered collapsed region for measurement of parameters such as curvature, strain and temperature. The up-tapered collapsed region helps in excitation of the cladding modes in PCF and these modes interfere with each other at the tapered region of PCF which is completely collapsed. Three tapered PCFs with varying geometry are fabricated and their effect on curvature sensitivity is analyzed. Experimental results show that the proposed sensor has a curvature sensitivity of 7.56 nm m-1 with negligible hysteresis effect. Moreover, the proposed sensor shows a strain sensitivity of 1.6 pm/μɛ along with a maximum temperature sensitivity of 51.6 pm °C-1. In addition to this, the response of the interference pattern to all these parameters is found to be linear.

  19. Pulse propagation in the tapered wiggler

    NASA Astrophysics Data System (ADS)

    Al-Abawi, H.; McIver, J. K.; Moore, G. T.; Scully, M. O.

    Theory and preliminary numerical calculations are presented for coherent optical and electron pulse propagation in a free-electron laser with a tapered wiggler. Since only trapped electrons contribute significantly to the laser radiation, it is possible to define generalized 'slow' space-time coordinates in terms of which the electron pulse envelope may be considered constant. The theory is outlined first for the helical wiggler and then is developed for an arbitrary quasiperiodic wiggler, using a more rigorous 'multiple-scaling' approach. In the latter case a modified definition of the electron phase angle is required, and optical harmonic generation is predicted. The numerical calculations show that substantial energy extraction is achievable, but that the optical pulse rapidly breaks up into a series of spikes in the time domain. Surprisingly, the optical spectrum remains quite smooth in appearance.

  20. Design of Structurally Efficient Tapered Struts (SETS)

    NASA Technical Reports Server (NTRS)

    Deo, Ravi; Benner, Harry; Vincent, Dawson; Olason, Eric; Harrison, Richard

    2010-01-01

    A study was conducted to develop mass efficient composite struts. A closed-form design methodology for composite struts was developed using well established analyses to predict Euler buckling, local wall buckling; compression strength, damage tolerance, and interlaminar shear at geometric gradients. The methodology was coded in a spreadsheet suitable for convenient and rapid sizing of tapered composite struts. This spreadsheet analysis was used to determine the influence of several variables such as material stiffness, strut diameter, and material allowables on strut weight for given loading conditions. The comparison showed that, while the Park Aerospace design method was well suited to preliminary sizing for a conservative design, the closed-form-analyses-based spreadsheet accounts for all possible failure modes and is a good optimum strut design tool. The report concludes with a set of recommendations for future work in analytical design and analysis methodology enhancements.

  1. Hierarchical tapered bar elements undergoing axial deformation

    NASA Technical Reports Server (NTRS)

    Ganesan, N.; Thampi, S. K.

    1992-01-01

    A method is described to model the dynamics of tapered axial bars of various cross sections based on the well-known Craig/Bampton component mode synthesis technique. This element is formed in terms of the static constraint modes and interface restrained normal modes. This is in contrast with the finite elements as implemented in NASTRAN where the interface restrained normal modes are neglected. These normal modes are in terms of Bessel functions. Restoration of a few of these modes leads to higher accuracy with fewer generalized coordinates. The proposed models are hierarchical so that all lower order element matrices are embedded in higher order element matrices. The advantages of this formulation compared to standard NASTRAN truss element formulation are demonstrated through simple numerical examples.

  2. Risk stratification algorithm for management of patients with dual modular taper total hip arthroplasty: consensus statement of the American Association of Hip and Knee Surgeons, the American Academy of Orthopaedic Surgeons and the Hip Society.

    PubMed

    Kwon, Young-Min; Fehring, Thomas K; Lombardi, Adolph V; Barnes, C Lowry; Cabanela, Miguel E; Jacobs, Joshua J

    2014-11-01

    Although 'dual taper' modular stems with interchangeable modular necks have the potential to optimize hip biomechanical parameters, there is increasing concern regarding the occurrence of adverse local tissue reactions from mechanically assisted crevice corrosion at the neck-stem taper junction. A systematic treatment approach (risk stratification algorithm) based on the currently available data is recommended to optimize patient management. While specialized tests such as metal ion analysis and MARS MRI are useful modalities in evaluating for adverse tissue reactions, over-reliance on any single investigative tool in the clinical decision-making process should be avoided. There should be a low threshold to perform a systematic evaluation of patients with dual taper stem total hip arthroplasty as early recognition and diagnosis will facilitate the initiation of appropriate treatment. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Increased efficacy of intermediate-dose cytarabine + G-CSF compared to DHAP + G-CSF for stem cell mobilization in patients with lymphoma: an analysis by the polish lymphoma research group.

    PubMed

    Giebel, Sebastian; Sadus-Wojciechowska, Maria; Halaburda, Kazimierz; Drozd-Sokolowska, Joanna; Wierzbowska, Agnieszka; Najda, Jacek; Mendrek, Wlodzimierz; Sobczyk-Kruszelnicka, Malgorzata; Nowicki, Mateusz; Holowiecki, Jerzy; Czerw, Tomasz

    2016-01-01

    Salvage regimens, like DHAP (dexamethasone, cytarabine, and cisplatin) are frequently used for stem cell mobilization in lymphoma. The aim of this study was to compare the efficacy of DHAP + G-CSF with intermediate-dose cytarabine (ID-AraC) + G-CSF, recently proposed as an alternative schedule. Consecutive patients with Hodgkin's or non-Hodgkin lymphoma who had received at least 2 lines of chemotherapy, mobilized with either DHAP (n = 51) or ID-AraC (n = 50) + G-CSF were included in the analysis. AraC was administered at the dose of 400 mg/m [1] bid intravenously for 2 days followed by filgrastim starting from day 5. In the AraC group, 96 % of patients collected at least 2 × 10 [2] CD34(+) cells/kg compared to 71 % in the DHAP group (p = 0.0006). The CD34(+) cell yield was 9.3 (0-30.3) × 10 [2]/kg vs. 5.6 (0-24.8) × 10 [2]/kg, respectively (p = 0.006). A single apheresis was sufficient to achieve the threshold number of CD34(+) cells in 82 % of the cases after AraC compared to 45 % after DHAP (p = 0.001). We conclude that stem cell mobilization using ID-AraC is associated with a significantly higher efficacy than DHAP, allowing for collection of the transplant material in almost all patients with lymphoma. Our observation suggests that ID-AraC + G-CSF may be a preferable mobilization regimen in this setting.

  4. Enclosed Cutting-And-Polishing Apparatus

    NASA Technical Reports Server (NTRS)

    Rossier, R. N.; Bicknell, B.

    1989-01-01

    Proposed apparatus cuts and polishes specimens while preventing contamination of outside environment or of subsequent specimens processed in it. Designed for use in zero gravity but also includes features useful in cutting and polishing of toxic or otherwise hazardous materials on Earth. Includes remote manipulator for handling specimens, cutting and polishing wire, inlets for gas and liquid, and outlets for waste liquid and gas. Replaceable plastic liner surrounds working space.

  5. Enclosed Cutting-And-Polishing Apparatus

    NASA Technical Reports Server (NTRS)

    Rossier, R. N.; Bicknell, B.

    1989-01-01

    Proposed apparatus cuts and polishes specimens while preventing contamination of outside environment or of subsequent specimens processed in it. Designed for use in zero gravity but also includes features useful in cutting and polishing of toxic or otherwise hazardous materials on Earth. Includes remote manipulator for handling specimens, cutting and polishing wire, inlets for gas and liquid, and outlets for waste liquid and gas. Replaceable plastic liner surrounds working space.

  6. Does fingernail polish affect pulse oximeter readings?

    PubMed

    Rodden, Ann M; Spicer, Leigh; Diaz, Vanessa A; Steyer, Terrence E

    2007-02-01

    Results from previous studies evaluating the effect of nail polish on oxygen saturation (SpO(2)) determined by pulse oximeter monitors are inconsistent. Establishing the effect of nail polish on SpO(2) is relevant to clinical practice, since removing nail polish requires clinical time and supplies. The objective of this study was to determine if fingernail polish affects SpO(2) as measured by two different pulse oximeter machines. Absorption spectra of 10 nail polish colors were obtained by spectrophotometry. Twenty-seven healthy volunteers with SpO(2)> or =95% participated. Using the Nellcor N20 and N595 pulse oximeters, the mean SpO(2) was measured on each of 10 nails with and without nail polish and using a side-to-side configuration. Means were compared using paired t-tests. Mean SpO(2) had a statistically significant decrease with brown and blue nail polish using both machines (p<0.05) but this was not clinically significant (<1% difference). Using the side-to-side configuration, the N595 oximeter had a statistically significant decrease in mean SpO(2) with red nail polish but again this was not clinically significant. Fingernail polish does not cause a clinically significant change in pulse oximeter readings in healthy people.

  7. Laser polishing of niobium for SRF applications

    SciTech Connect

    Zhao, Liang; Klopf, J. Michael; Reece, Charles E.; Kelley, Michael

    2013-09-01

    Smooth interior surfaces are desired for niobium SRF cavities, now obtained by buffered chemical polish (BCP) and/or electropolish (EP). Laser polishing is a potential alternative, having advantages of speed, freedom from chemistry and in-process inspection. Here we show that laser polishing can produce smooth topography with Power Spectral Density (PSD) measurements similar to that obtained by EP. We studied the influence of the laser power density and laser beam raster rate on the surface topography. These two factors need to be combined carefully to smooth the surface without damaging it. Computational modeling was used to simulate the surface temperature and explain the mechanism of laser polishing.

  8. Development of small bore, high speed tapered roller bearing

    NASA Technical Reports Server (NTRS)

    Morrison, F. R.; Gassel, S. S.; Bovenkerk, R. L.

    1981-01-01

    The performance of four rolling bearing configurations for use on the input pinion shaft of a proposed commercial helicopter transmission was evaluated. The performance characteristics of a high speed tapered roller bearing operating under conditions comparable to those existing at this input pinion shaft were defined. The tapered roller bearing shaft support configuration was developed for the gearbox using commercially available bearing designings. The configuration was optimized and interactive thermomechanically system analyzed. Automotive pinion quality tapered roller bearings were found to be reliable under load and speed conditions in excess of those anticipated in the helicopter transmission. However, it is indicated that the elastohydrodynamic lubricant films are inadequate.

  9. Free torsional vibrations of tapered cantilever I-beams

    NASA Astrophysics Data System (ADS)

    Rao, C. Kameswara; Mirza, S.

    1988-08-01

    Torsional vibration characteristics of linearly tapered cantilever I-beams have been studied by using the Galerkin finite element method. A third degree polynomial is assumed for the angle of twist. The analysis presented is valid for long beams and includes the effect of warping. The individual as well as combined effects of linear tapers in the width of the flanges and the depth of the web on the torsional vibration of cantilever I-beams are investigated. Numerical results generated for various values of taper ratios are presented in graphical form.

  10. Gold nanoparticles modified double-tapered fiber for SERS detection

    NASA Astrophysics Data System (ADS)

    Zhao, Chunqin; Chen, Na; liu, Shupeng; Chen, Zhenyi; Wang, Tingyun

    2017-06-01

    Double-tapered fiber probes modified with gold nanoparticles were fabricated for the surface-enhanced Raman scattering (SERS) sensing. Its performance was compared with the fiber SERS probes of flat end and of single-tapered structure. The remote detection performances of three fiber probe structures were compared by detecting rhodamine 6G (R6G) aqueous solutions with the different concentrations. The results of remote detection of R6G aqueous solution indicate that double-tapered fiber probe with the detection limit of 10-9 M is the most sensitive.

  11. Micro-taper as focusing or scattering optical element

    SciTech Connect

    Degtyarev, S. A. Ustinov, A. V. Khonina, S. N.

    2016-04-13

    We consider micro-taper (narrow refractive axicon) as optical element which is focusing or scattering in dependence on axicon’s cone angle. The diffraction of laser beam by micro-taper is simulated by two methods: multiply internal ray reflections using geometrical approach and Helmholtz equation solving using finite elements method. Based on ray optics we derive analytic formulas for conical angles values which provide focusing or scattering features of micro-taper. Numerical simulation by finite elements method verifies theoretical results.

  12. Nonlinear transmission through a tapered fiber in rubidium vapor

    SciTech Connect

    Hendrickson, S. M.; Pittman, T. B.; Franson, J. D.

    2009-02-15

    Subwavelength-diameter tapered optical fibers surrounded by rubidium vapor can undergo a substantial decrease in transmission at high atomic densities due to the accumulation of rubidium atoms on the surface of the fiber. Here we demonstrate the ability to control these changes in transmission using light guided within the taper. We observe transmission through a tapered fiber that is a nonlinear function of the incident power. This effect can also allow a strong control beam to change the transmission of a weak probe beam.

  13. Some novel features of an FEL oscillator with tapered undulator

    SciTech Connect

    Saldin, E.L.; Schneidmiller, E.A.; Yurkov, M.V.

    1995-12-31

    A one-dimensional analysis of an FEL oscillator with a linear undulator tapering is presented. Some principally novel results have been obtained. The origin of these results is in principal difference between the FEL oscillator and an FEL amplifier. In the case of the FEL amplifier the frequency of the amplified wave and all the other parameters are defined by an experimenter. Contrary to this, the case of the FEL oscillator with tapered undulator is more complicated. The lasing frequency is defined by the maximum of the small-signal gain and depends on the tapering depth in some complex way.

  14. Perceptions of and Attitudes towards Regional Varieties of Polish: Views from Two Polish Provinces

    ERIC Educational Resources Information Center

    Milobog, Magdalena; Garrett, Peter

    2011-01-01

    This paper reports a study of perceptions and attitudes relating to regional varieties of Polish. The methodology followed folk linguistic approaches to attitudes research. Respondents in two Polish provinces were asked to draw on a map of Poland where they thought the main regional varieties of Polish were spoken, and then to name and…

  15. Perceptions of and Attitudes towards Regional Varieties of Polish: Views from Two Polish Provinces

    ERIC Educational Resources Information Center

    Milobog, Magdalena; Garrett, Peter

    2011-01-01

    This paper reports a study of perceptions and attitudes relating to regional varieties of Polish. The methodology followed folk linguistic approaches to attitudes research. Respondents in two Polish provinces were asked to draw on a map of Poland where they thought the main regional varieties of Polish were spoken, and then to name and…

  16. Polish spaces of causal curves

    NASA Astrophysics Data System (ADS)

    Miller, Tomasz

    2017-06-01

    We propose and study a new approach to the topologization of spaces of (possibly not all) future-directed causal curves in a stably causal spacetime. It relies on parametrizing the curves ;in accordance; with a chosen time function. Thus obtained topological spaces of causal curves are separable and completely metrizable, i.e. Polish. The latter property renders them particularly useful in the optimal transport theory. To illustrate this fact, we explore the notion of a causal time-evolution of measures in globally hyperbolic spacetimes and discuss its physical interpretation.

  17. Tripol condensate polishing - operational experience

    SciTech Connect

    Swainsbury, D.

    1995-01-01

    This paper gives a brief outline of the Mission Energy Management Australia Company who operate and maintain the Loy Yang B Power Station in the Latrobe Valley, Victoria, Australia. Details of the plant configuration, the water/steam circuit and cycle chemistry are discussed. The arrangement of the TRIPOL Condensate Polishing Plant and it`s operational modes are examined. Results of the first twelve months operation of the TRIPOL plant are detailed. Levels of crud removal during early commissioning phases employing the pre-filter are presented. Typical parameters achieved during a simulated condenser leak and an operational run beyond the ammonia break point are also documented.

  18. Polish Foundation for Energy Efficiency

    SciTech Connect

    1995-12-31

    The Polish Foundation for Energy Efficiency (FEWE) was established in Poland at the end of 1990. FEWE, as an independent and non-profit organization, has the following objectives: to strive towards an energy efficient national economy, and to show the way and methods by use of which energy efficiency can be increased. The activity of the Foundation covers the entire territory of Poland through three regional centers: in Warsaw, Katowice and Cracow. FEWE employs well-known and experienced specialists within thermal and power engineering, civil engineering, economy and applied sciences. The organizer of the Foundation has been Battelle Memorial Institute - Pacific Northwest Laboratories from the USA.

  19. The relation between titanium taper corrosion and cobalt-chromium bearing wear in large-head metal-on-metal total hip prostheses: a retrieval study.

    PubMed

    Witt, F; Bosker, B H; Bishop, N E; Ettema, H B; Verheyen, C C P M; Morlock, M M

    2014-09-17

    Revision of hip implants due to adverse tissue reactions to metal debris has been associated with wear and corrosion of the metal-on-metal bearing articulation and the modular taper interface. Bearing articulation wear is increased in conditions of poor lubrication, which can also lead to high friction moments that may cause corrosion at the taper interface. This suggests that wear of the bearing and increased corrosion of the taper interface should occur simultaneously, which was investigated in this study. Forty-three large-diameter cobalt-chromium bearings of the same design, implanted with a titanium stem using a titanium adapter, were retrieved at revision at a single center. Retrievals were grouped according to visual inspection of the female taper surface of the adapter into slight and severe corrosion groups. Volume change of bearing and taper surfaces was assessed using a coordinate measurement machine. Serum ion concentrations were determined for forty-three patients, whereas tissue metal concentration was measured for twelve patients. Severe taper corrosion was observed in 30% of the retrievals. Corrosion was observed either as material deposition or wear. The overall bearing wear rate was significantly higher in the group with severe taper corrosion than in the group with slight corrosion (7.2 ± 9.0 mm(3)/yr versus 3.1 ± 6.8 mm(3)/yr, respectively; p = 0.023) as were the serum cobalt (40.5 ± 44.9 μg/L versus 15.2 ± 23.9 μg/L, respectively; p = 0.024) and chromium ion concentrations (32.7 ± 32.7 μg/L versus 12.0 ± 15.1 μg/L, respectively; p = 0.019). Serum metal ion concentrations were more consistent indicators of wear than tissue metal concentrations. The increased bearing articulation wear and serum metal ion concentrations in cases with taper interface corrosion support the hypothesis that increased friction in the joint articulation is one of the factors responsible for simultaneous articulation and taper damage. However, independent taper

  20. Cement in cement revision of the femoral component using a collarless triple taper: a midterm clinical and radiographic assessment.

    PubMed

    Stefanovich-Lawbuary, Natalija S; Parry, Michael C; Whitehouse, Michael R; Blom, Ashley W

    2014-10-01

    This study describes the midterm clinical and radiological results of the cement in cement technique for the femur using a collarless triple taper. Radiographic assessment was made retrospectively from 44 patients at two time points. Clinical outcomes included the Oxford Hip Score, EQ5D and Self Reported Patient Satisfaction Scale. Implant and patient survival were also recorded. The mean clinical follow up period was 5years 3months and the radiological follow up 2years 10months. The mean OHS was 34, the mean EQ5D 0.814 and the mean SAPS 94. Kaplan-Meier survival with revision, as the end point was 95.2% at 11years with a survivorship of 76.5% with death as the end point. Cement in cement revision using a collarless triple tapered stem demonstrates promising results both clinically and radiologically at midterm follow up. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Perfluorinated plastic optical fiber tapers for evanescent wave sensing.

    PubMed

    Gravina, Roberto; Testa, Genni; Bernini, Romeo

    2009-01-01

    In this work we describe the fabrication and the characterization of perfluorinated plastic-cladded optical fiber tapers. The heat-and-pull procedure has been used to fabricate symmetric tapers. Devices with different taper ratio have been produced and the repeatability of the process has been verified. The very low refractive indexes of the core-cladding perfluorinated polymers (n = 1.35-1.34) permit a strong enhancement of the evanescent wave power fraction in aqueous environments (n = 1.33), making them very attractive for evanescent wave sensing. The tapers have been characterized carrying out evanescent field absorbance measurements with different concentrations of methylene blue in water and fluorescence collection measurements in an aqueous solution containing Cy5 dye. A good sensitivity, tightly related to the low refractive index of the core-cladding materials and the geometrical profile, has been shown.

  2. Tapered fluorotellurite microstructured fibers for broadband supercontinuum generation.

    PubMed

    Wang, Fang; Wang, Kangkang; Yao, Chuanfei; Jia, Zhixu; Wang, Shunbin; Wu, Changfeng; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

    2016-02-01

    Fluorotellurite microstructured fibers (MFs) based on TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method. Tapered fluorotellurite MFs with varied transition region lengths are prepared by employing an elongation machine. By using a tapered fluorotellurite MF with a transition region length of ∼3.3  cm as the nonlinear medium and a 1560 nm femtosecond fiber laser as the pump source, broadband supercontinuum generation covering from 470 to 2770 nm is obtained. The effects of the transition region length of the tapered fluorotellurite MF on supercontinuum generation are also investigated. Our results show that tapered fluorotellurite MFs are promising nonlinear media for generating broadband supercontinuum light expanding from visible to mid-infrared spectral region.

  3. Perfluorinated Plastic Optical Fiber Tapers for Evanescent Wave Sensing

    PubMed Central

    Gravina, Roberto; Testa, Genni; Bernini, Romeo

    2009-01-01

    In this work we describe the fabrication and the characterization of perfluorinated plastic-cladded optical fiber tapers. The heat-and-pull procedure has been used to fabricate symmetric tapers. Devices with different taper ratio have been produced and the repeatability of the process has been verified. The very low refractive indexes of the core-cladding perfluorinated polymers (n = 1.35−1.34) permit a strong enhancement of the evanescent wave power fraction in aqueous environments (n = 1.33), making them very attractive for evanescent wave sensing. The tapers have been characterized carrying out evanescent field absorbance measurements with different concentrations of methylene blue in water and fluorescence collection measurements in an aqueous solution containing Cy5 dye. A good sensitivity, tightly related to the low refractive index of the core-cladding materials and the geometrical profile, has been shown. PMID:22303182

  4. Radiation Effects on Fused Biconical Taper Wavelength Division Multiplexers

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C.; Swift, Gary M.; Dubovitsky, Serge; Bartman, Randall K.; Barnes, Charles E.; Dorsky, Leonard

    1994-01-01

    The effects of radiation on fused biconical taper wavelength division multiplexers are presented. A theoretical model indicates that index changes in the fiber are primarily responsible for the degradation of these devices.

  5. Spontaneous radiation from relativistic electrons in a tapered undulator

    NASA Technical Reports Server (NTRS)

    Bosco, P.; Colson, W. B.

    1983-01-01

    The spectrum, angular distribution, polarization, and coherence properties of the radiation emitted by relativistic electrons undulating through a quasiperiodic tapered magnetic field are studied. Tapering the wavelength and/or field strength along the undulator's axis has the effect of spreading the spectral line to higher frequencies; interference over this broader spectral range results in a more complex line shape. The angular dependence, on the other hand, is not affected by the amount of taper. The polarization of the radiation in the forward direction is determined by the transverse polarization of the undulator, but the polarization changes off axis. The radiation patterns predicted here are distinct from those of untapered undulators and their detection is now feasible. They will provide useful diagnostics of electron trajectories and threshold behavior in free-electron-laser oscillators using tapered undulators.

  6. Optical coupling and splitting with two parallel waveguide tapers.

    PubMed

    Tao, S H

    2011-01-17

    A coupling and splitting device comprising a width taper and a spatial-modulated subwavelength grating waveguide (SSGW) is proposed. The width taper is a waveguide with increasing width and the SSGW is a waveguide grating whose width and thickness are constant but the filling factor increases along the light propagation. Thus, the effective index of the subwavelength grating increases according to the effective medium theory. Light of orthogonal polarizations from a single-mode fiber can be coupled efficiently with the two parallel tapers. Furthermore, the coupled lights of orthogonal polarizations in the two tapers can be further split with connecting bent waveguides. Fabrication of the device is fully compatible with current complementary metal oxide semiconductor technology.

  7. Quantification of material loss from the neck piece taper junctions of a bimodular primary hip prosthesis. A retrieval study from 27 failed Rejuvenate bimodular hip arthroplasties.

    PubMed

    Buente, D; Huber, G; Bishop, N; Morlock, M

    2015-10-01

    The early failure and revision of bimodular primary total hip arthroplasty prostheses requires the identification of the risk factors for material loss and wear at the taper junctions through taper wear analysis. Deviations in taper geometries between revised and pristine modular neck tapers were determined using high resolution tactile measurements. A new algorithm was developed and validated to allow the quantitative analysis of material loss, complementing the standard visual inspection currently used. The algorithm was applied to a sample of 27 retrievals (in situ from 2.9 to 38.1 months) of the withdrawn Rejuvenate modular prosthesis. The mean wear volumes on the flat distal neck piece taper was 3.35 mm(3) (0.55 to 7.57), mainly occurring in a characteristic pattern in areas with high mechanical loading. Wear volume tended to increase with time to revision (r² = 0.423, p = 0.001). Implant and patient specific data (offset, stem size, patient's mass, age and body mass index) did not correlate with the amount of material loss observed (p > 0.078). Bilaterally revised implants showed higher amounts of combined total material loss and similar wear patterns on both sides. The consistent wear pattern found in this study has not been reported previously, suggesting that the device design and materials are associated with the failure of this prosthesis. ©2015 The British Editorial Society of Bone & Joint Surgery.

  8. Attack polish for nickel-base alloys and stainless steels

    DOEpatents

    Steeves, Arthur F.; Buono, Donald P.

    1983-01-01

    A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels. The chemical attack polish comprises Fe(NO.sub.3).sub.3, concentrated CH.sub.3 COOH, concentrated H.sub.2 SO.sub.4 and H.sub.2 O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

  9. Method of polishing nickel-base alloys and stainless steels

    DOEpatents

    Steeves, Arthur F.; Buono, Donald P.

    1981-01-01

    A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels. The chemical attack polish comprises Fe(NO.sub.3).sub.3, concentrated CH.sub.3 COOH, concentrated H.sub.2 SO.sub.4 and H.sub.2 O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

  10. The first Polish total laryngectomies

    PubMed Central

    Paprocka-Borowicz, Małgorzata; Pozowski, Andrzej; Kuciel-Lewandowska, Jadwiga

    2013-01-01

    The total removal of the larynx (total laryngectomy), performed in 1872 by the well-known Viennese surgeon Christian A. Theodor Billroth (1829–1894), was an epoch-making event in the history of surgery and laryngology. This paper presents the first surgeons who performed this operation. The first Pole who performed a total laryngectomy (1877) was Julian Kosiński (1833–1914), head of the Surgical Clinic of Imperial University Warsaw. It was the 14th operation of this kind in the world. Several laryngectomies were carried out by Franciszek Ksawery Jawdyński (1851–1896), called the father of Polish head and neck surgery, who was the first Pole to excise a malignant neck cancer together with the lymph nodes. The next total laryngectomies were performed by the following Polish surgeons: Jan Mikulicz-Radecki (1850–1905), Władysław H.S. Krajewski (1855–1907), Alfred Obaliński (1843–1898). According to Jan Sędziak, by 1897 Poland with 16 laryngectomies (per 188 carried out) had occupied the fourth position in the world. The failures of the first laryngectomies were due to such factors as the ignorance of shock pathophysiology, the inability to ensure the patency of the airways during and after the operation, which would result in lung and mediastinum infections, massive haemorrhages and so on. But the primary cause was the lack of constructive collaboration between the laryngologists and the surgeons. PMID:24592132

  11. Buffered Electrochemical Polishing of Niobium

    SciTech Connect

    Gianluigi Ciovati; Tian, Hui; Corcoran, Sean

    2011-03-01

    The standard preparation of superconducting radio-frequency (SRF) cavities made of pure niobium include the removal of a 'damaged' surface layer, by buffered chemical polishing (BCP) or electropolishing (EP), after the cavities are formed. The performance of the cavities is characterized by a sharp degradation of the quality factor when the surface magnetic field exceeds about 90 mT, a phenomenon referred to as 'Q-drop.' In cavities made of polycrystalline fine grain (ASTM 5) niobium, the Q-drop can be significantly reduced by a low-temperature (? 120 °C) 'in-situ' baking of the cavity if the chemical treatment was EP rather than BCP. As part of the effort to understand this phenomenon, we investigated the effect of introducing a polarization potential during buffered chemical polishing, creating a process which is between the standard BCP and EP. While preliminary results on the application of this process to Nb cavities have been previously reported, in this contribution we focus on the characterization of this novel electrochemical process by measuring polarization curves, etching rates, surface finish, electrochemical impedance and the effects of temperature and electrolyte composition. In particular, it is shown that the anodic potential of Nb during BCP reduces the etching rate and improves the surface finish.

  12. Optimization of tapered busses for solar cell contacts

    NASA Technical Reports Server (NTRS)

    Landis, G. A.

    1979-01-01

    Some fraction of the power produced by a solar cell is necessarily lost by series resistance associated with the metallized contact grid and by shadowing of cell active area by the grid. There are several approaches to reducing these losses, such as choosing a more efficient pattern, optimizing line spacing, and using tapered buses. The present paper analyzes tapered lines and derives from this analysis a theoretical lower bound to metallization power loss, independent of pattern chosen.

  13. Fabrication and Testing of Tapered Electro-spray Nozzles

    DTIC Science & Technology

    2012-09-01

    oxidized nozzle with broken top cap. 15 The ultrasonic breaking of the etch mask was found to be a low-yield methodology, with some caps breaking...Fabrication and Testing of Tapered Electro-spray Nozzles by Brendan M. Hanrahan and C. Mike Waits ARL-TR-6226 September 2012...September 2012 Fabrication and Testing of Tapered Electro-spray Nozzles Brendan M. Hanrahan and C. Mike Waits Sensors and Electron Devices

  14. Multimode tapered optical light pipe for illumination systems

    NASA Astrophysics Data System (ADS)

    Romańczuk, Patryk; Pietrzycki, Marcin; Źmojda, Jacek; Kochanowicz, Marcin; Dorosz, Dominik

    2015-09-01

    In the article the multimode tapered optical light pipe for illumination systems was investigated. Based on tree light emitting diodes at the wavelength of 460 nm (blue), 528 nm (green) and 631 nm (red) possibility of white light emission on the output surface of the tapered light pipe was submitted. Influence of optical power of LEDs on the colour coordinates (CIE-1931) has been investigated.

  15. Optical inclinometer based on fibre-taper-modal Michelson interferometer

    NASA Astrophysics Data System (ADS)

    Amaral, L. M. N.; Frazão, O.; Santos, J. L.; Lobo Ribeiro, A. B.

    2010-09-01

    An inclinometer sensor based on optical fibre-taper-modal Michelson interferometer is demonstrated. The magnitude of the tilt (bending angle of the fibre taper interferometer) is obtained by passive interferometric interrogation based on the generation of two quadrature phase-shifted signals from two fibre Bragg gratings. Optical phase-to-rotation sensitivity of 1.13 rad/degree with a 14 mrad/√Hz resolution is achieved.

  16. Advanced techniques for computer-controlled polishing

    NASA Astrophysics Data System (ADS)

    Schinhaerl, Markus; Stamp, Richard; Pitschke, Elmar; Rascher, Rolf; Smith, Lyndon; Smith, Gordon; Geiss, Andreas; Sperber, Peter

    2008-08-01

    Computer-controlled polishing has introduced determinism into the finishing of high-quality surfaces, for example those used as optical interfaces. Computer-controlled polishing may overcome many of the disadvantages of traditional polishing techniques. The polishing procedure is computed in terms of the surface error-profile and the material removal characteristic of the polishing tool, the influence function. Determinism and predictability not only enable more economical manufacture but also facilitate considerably increased processing accuracy. However, there are several disadvantages that serve to limit the capabilities of computer-controlled polishing, many of these are considered to be issues associated with determination of the influence function. Magnetorheological finishing has been investigated and various new techniques and approaches that dramatically enhance the potential as well as the economics of computer-controlled polishing have been developed and verified experimentally. Recent developments and advancements in computer-controlled polishing are discussed. The generic results of this research may be used in a wide variety of alternative applications in which controlled material removal is employed to achieve a desired surface specification, ranging from surface treatment processes in technical disciplines, to manipulation of biological surface textures in medical technologies.

  17. BEGINNING POLISH, VOLUME ONE. YALE LINGUISTIC SERIES.

    ERIC Educational Resources Information Center

    SCHENKER, ALEXANDER M.

    BASED ON A MODERN LINGUISTIC ANALYSIS OF THE POLISH LANGUAGE, THIS TWO-VOLUME TEXT IS APPROPRIATE FOR A ONE-YEAR INTENSIVE COURSE. VOLUME I INCLUDES 25 LESSONS, EACH DIVIDED INTO--SENTENCES (DIALOGS), GRAMMAR, EXERCISES, AND VOCABULARY LISTS. THE INTRODUCTION PRESENTS A BRIEF CONTRASTIVE ANALYSIS OF POLISH AND RUSSIAN, AND THERE IS INCLUDED A…

  18. Holding fixture for metallographic mount polishing

    DOEpatents

    Barth, Clyde H.; Cramer, Charles E.

    1997-01-01

    A fixture for holding mounted specimens for polishing, having an arm; a body attached to one end of the arm, the body having at least one flange having an opening to accommodate a mounted specimen; and a means applying pressure against the outer surface of the mounted specimen to hold the specimen in contact with the polishing surface.

  19. Holding fixture for metallographic mount polishing

    DOEpatents

    Barth, C.H.; Cramer, C.E.

    1997-12-30

    A fixture is described for holding mounted specimens for polishing, having an arm; a body attached to one end of the arm, the body having at least one flange having an opening to accommodate a mounted specimen; and a means applying pressure against the outer surface of the mounted specimen to hold the specimen in contact with the polishing surface. 3 figs.

  20. (PECASE 08) - ION-Conducting Network Membranes Using Tapered Block Copolymers

    DTIC Science & Technology

    2015-07-08

    doped normal-tapered materials , and a similar window was not detectable in the corresponding non-tapered and inverse-tapered polymers. Additionally...the effective interaction parameters, χeff, were reduced substantially in the tapered materials in comparison to their non-tapered counterparts...indicating an ability to process these battery materials at lower temperatures, with less solvent, and over shorter time scales. Thus, it was

  1. Mean Scatterer Spacing Estimation Using Multi-Taper Coherence

    PubMed Central

    Rubert, Nicholas; Varghese, Tomy

    2013-01-01

    It has been hypothesized that estimates of mean scatterer spacing are useful indicators for pathological changes to the liver. A commonly employed estimator of the mean scatterer spacing is the location of the maximum of the collapsed average of coherence of the ultrasound radio-frequency signal. To date, in ultrasound, estimators for this quantity have been calculated with a single taper. Using frequency-domain Monte Carlo simulations, we demonstrate that multi-taper estimates of coherence are superior to single-taper estimates for predicting mean scatterer spacing. Scattering distributions were modeled with Gamma-distributed scatterers for fractional standard deviations in scatterer spacings of 5, 10, and 15% at a mean scatterer spacing of 1 mm. Additionally, we demonstrate that we can distinguish between ablated liver tissue and unablated liver tissue based on signal coherence. We find that, on the average, signal coherence is elevated in the liver relative to signal coherence of received echoes from thermally ablated tissue. Additionally, our analysis indicates that a tissue classifier utilizing the multi-taper estimate of coherence has the potential to distinguish between ablated and unablated tissue types better than a single-taper estimate of coherence. For a gate length of 5 mm, we achieved an error rate of only 8.7% when sorting 23 ablated and 23 unablated regions of interest (ROIs) into classes based on multi-taper calculations of coherence. PMID:25004470

  2. Suppression of acoustic streaming in tapered pulse tubes

    SciTech Connect

    Olson, J.R.; Swift, G.W.

    1998-12-31

    In a pulse tube cryocooler, the gas in the pulse tube can be thought of as an insulating piston, transmitting pressure and velocity from the cold heat exchanger to the hot end of the pulse tube. Unfortunately, convective heat transfer can carry heat from the hot end to the cold end and reduce the net cooling power. Here, the authors discuss one driver of such convection: steady acoustic streaming as generated by interactions between the boundary and the oscillating pressure, velocity, and temperature. Using a perturbation method, they have derived an analytical expression for the streaming in a tapered pulse tube with axially varying mean temperature in the acoustic boundary layer limit. The calculations showed that the streaming depends strongly on the taper angle, the ratio of velocity and pressure amplitudes, and the phase between the velocity and pressure, but it depends only weakly on the mean temperature profile and is independent of the overall oscillatory amplitude. With the appropriate tapering of the tube, streaming can be eliminated for a particular operating condition. Experimentally, the authors have demonstrated that an orifice pulse tube cryocooler with the calculated zero-streaming taper has more cooling power than one with either a cylindrical tube or a tapered pulse tube with twice the optimum taper angle.

  3. Mechanics and complications of reverse shoulder arthroplasty: morse taper failure analysis and prospective rectification

    NASA Astrophysics Data System (ADS)

    Hoskin, HLD; Furie, E.; Collins, W.; Ganey, TM; Schlatterer, DR

    2017-05-01

    Since Sir John Charnley began his monumental hip arthroplasty work in 1958, clinical researchers have been incrementally improving longevity and functionality of total joint systems, although implant failure occurs on occasion. The purpose of this study is to report the fracture of the humeral tray Morse taper of a reverse total shoulder system (RTSS), which to date has not been reported with metallurgic analysis for any RTSS. There was no reported antecedent fall, motor vehicle collision, or other traumatic event prior to implant fracture in this case. Analysis was performed on the retrieved failed implant by Scanning Electron Microscopy (SEM) and Electron Dispersion Spectroscopy (EDS) in an attempt to determine the failure method, as well as to offer improvements for future implants. At the time of revision surgery all explants were retained from the left shoulder of a 61-year old male who underwent a non-complicated RTSS 4 years prior. The explants, particularly the cracked humeral tray, were processed as required for SEM and EDS. Analysis was performed on the failure sites in order to determine the chemical composition of the different parts of the implant, discover the chemical composition of the filler metal used during the electron beam welding process, and to detect any foreign elements that could suggest corrosion or other evidence of failure etiology. Gross visual inspection of all explants revealed that implant failure was a result of dissociation of the taper from the humeral tray at the weld, leaving the Morse taper embedded in the humeral stem while the tray floated freely in the patient’s shoulder. SEM further confirmed the jagged edges noted grossly at the weld fracture site, both suggesting failure due to torsional forces. EDS detected elevated levels of carbon and oxygen at the fracture site on the taper only and not on the humeral tray. In order to determine the origin of the high levels of C and O, it was considered that in titanium alloys, C

  4. Molecular Dynamics Simulations of Penetrants in Microphase Separated Tapered Diblock Copolymers

    NASA Astrophysics Data System (ADS)

    Seo, Youngmi; Brown, Jonathan R.; Hall, Lisa M.

    Tapered AB diblock copolymers contain pure A and B monomer blocks on the ends with a tapered midblock of intermediate composition, providing taper length as an additional tuning parameter to control microphase separation and interfacial behavior. We model the midblock as a statistical linear gradient from pure A to pure B. Recent experiments with salt dissolved in one of microphases show that a certain length of taper increases ion conductivity while the same length of inverse taper lowers conductivity. We perform coarse-grained molecular dynamics simulations of tapered copolymers with monomer sized penetrants, which have preferential interactions with one microphase, to better understand this observation and the general effects of tapering on dynamics. We calculate penetrant diffusion, polymer relaxation times, and other quantities over the range from 0% (diblock) to 100% (full gradient) taper length, with the taper direction either normal or inverse (with the A side of the taper connected to the pure B block). Normal taper results typically lie between those of diblocks and full gradients, while inverse tapers show strong nonmonotonic behavior as a function of taper length. For intermediate length inverse tapers, penetrant and monomer dynamics are significantly slower than those of diblocks or normal tapers, and this relates to the folding of the inverse chains back and forth across the interface. To provide further insight, we also compare to the dynamics of random copolymers of various compositions. Based upon work supported by NSF Grant 1454343.

  5. Experiences with polishing electroless nickel

    SciTech Connect

    Brown, N.J.; Taylor, J.S.; Fuchs, B.A.

    1991-04-01

    During recent years the bureaucracy has become increasingly rigid in demanding a mechanical observance of the minimum bid specified on the simplest terms. Qualifications of the vendor and specifications of the product are increasingly viewed as attempts to thwart the progress of the process toward minimum quality, Any such qualification or specification must be justified as to not only reasonableness but necessity. This provides the purpose of this paper, to record forever the existence of the wild dingleberry and to disclose its habits with respect to laps and the marvelous effects it has on the emotional state of the lappers. Among metal polishers, the term dingleberry refers to a type of nodule or wartlike structure sometimes seen in isolation and occasionally in considerable profusion particularly in chemically plated surfaces. 2 refs.

  6. Psychological profile of Polish skydivers.

    PubMed

    Próchniak, Piotr

    2011-02-01

    To identify personality factors, personal values, time perspective, and attitude toward death of 53 Polish skydivers (M age = 28.4 yr., SD = 9.8) and 59 low-risk sport athletes (controls, M age = 27.3 yr., SD = 5.3), several scales were used. These were the Zuckerman-Kuhlman Personality Questionnaire, Schwartz's Value Survey, the Present and Future Time Perspective Questionnaire, and Death Attitude Questionnaire. It was found that skydivers scored higher on Impulsive Sensation Seeking, Hedonism, Stimulation, and Self-direction values, concentration on the present, preferring a fast death, and belief about controlling death in comparison to the control group. Skydivers also scored lower on Tradition, Universalism, and Benevolence values in comparison to the control group.

  7. Drug consumption among Polish centenarians.

    PubMed

    Rajska-Neumann, A; Mossakowska, M; Klich-Rączka, A; Życzkowska, J; Grześkowiak, E; Shieh, S; Wieczorowska-Tobis, K

    2011-01-01

    The aim of the study was to describe the quantitative and qualitative aspects of pharmacotherapy of Polish centenarians. The studied group consisted of 92 centenarians (mean age: 101.7±1.2 years, 77 females, mean age: 101.5±1.2; 15 males mean age: 102.2±1.2). Among the studied subjects, 18 individuals (19.6% of all subjects) did not use any drugs in his or her daily regimen. The mean number of drugs per person was 2.5±2.5 drugs (prescription drugs: 1.9±2.2 and non-prescription drugs: 0.5±0.8). Fifty-six centenarians (60.9% of all studied subjects) took concomitantly 0-3 drugs daily while 36 (39.1%) took more than 3 drugs daily. Within this group, 30 centenarians (32.6%) took 5 or more drugs concomitantly every day. The most commonly used groups of drugs were: gastrointestinal drugs (55 centenarians, 74.3% of all drug consumed), cardiovascular drugs (51 centenarians, 68.9%) and central nervous system drugs (N) (38 centenarians, 51.4%). In the studied group, 6 persons (8.1% of all drug consumers) were taking one potentially inappropriate drug based on the Beers criteria. To conclude, the mean number of drugs, the prevalence of polypharmacy, and the tendency for potential inappropriateness of treatment are lower among Polish centenarians comparing to the common elderly. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  8. Careers of young Polish chemists.

    PubMed

    Kosmulski, Marek

    Typical young Polish scientist is an alumnus of doctoral studies at the same university and department where he/she completed his/her Master degree. The career is continued by receiving a habilitation at the same university and department. Then a holder of habilitation is promoted to a tenured position at the same university and department. Detailed analysis of scientific careers of 154 recent Ph.D. recipients and of 16 habilitation candidates in chemistry from University of Warsaw is presented. More than 96 % of the Ph.D. theses were results of doctoral studies. A typical doctor is Polish citizen (>98 %), alumnus/alumna of the University of Warsaw (>85 %), holder of Master degree in chemistry (88 %) who joined the Ph.D. program at the same university directly after having completed his/her Master degree, and completed the Ph.D. program 5.5 years after completion of Master degree. A fraction of recent female Ph.D. recipients in chemistry (61 %) is very high as compared with the corresponding fractions in other countries (e.g., USA), but it is still substantially lower than the fraction of female Master degree recipients. In recent habilitation candidates, the female ratio is 50 %, thus relative male dominance is observed at higher levels. At least one-third of the recent Ph.D. recipients were employed by the same university, where they received their Ph.D., while the fraction of the recent Ph.D. recipients employed by other universities in Poland was below 5 %. High degree of academic inbreeding is due to the legal system in Poland, which (nominally) is designed to prevent academic inbreeding, but the regulations can be easily circumvented. Over 10 % of the recent Ph.D. recipients found post-doctoral positions abroad, chiefly in EU countries and in the USA.

  9. Convergent Polishing: A Simple, Rapid, Full Aperture Polishing Process of High Quality Optical Flats & Spheres

    PubMed Central

    Suratwala, Tayyab; Steele, Rusty; Feit, Michael; Dylla-Spears, Rebecca; Desjardin, Richard; Mason, Dan; Wong, Lana; Geraghty, Paul; Miller, Phil; Shen, Nan

    2014-01-01

    Convergent Polishing is a novel polishing system and method for finishing flat and spherical glass optics in which a workpiece, independent of its initial shape (i.e., surface figure), will converge to final surface figure with excellent surface quality under a fixed, unchanging set of polishing parameters in a single polishing iteration. In contrast, conventional full aperture polishing methods require multiple, often long, iterative cycles involving polishing, metrology and process changes to achieve the desired surface figure. The Convergent Polishing process is based on the concept of workpiece-lap height mismatch resulting in pressure differential that decreases with removal and results in the workpiece converging to the shape of the lap. The successful implementation of the Convergent Polishing process is a result of the combination of a number of technologies to remove all sources of non-uniform spatial material removal (except for workpiece-lap mismatch) for surface figure convergence and to reduce the number of rogue particles in the system for low scratch densities and low roughness. The Convergent Polishing process has been demonstrated for the fabrication of both flats and spheres of various shapes, sizes, and aspect ratios on various glass materials. The practical impact is that high quality optical components can be fabricated more rapidly, more repeatedly, with less metrology, and with less labor, resulting in lower unit costs. In this study, the Convergent Polishing protocol is specifically described for fabricating 26.5 cm square fused silica flats from a fine ground surface to a polished ~λ/2 surface figure after polishing 4 hr per surface on a 81 cm diameter polisher. PMID:25489745

  10. An experimental study of an FEL oscillator with a linear taper

    NASA Astrophysics Data System (ADS)

    Benson, S.; Gubeli, J.; Neil, G. R.

    2001-12-01

    Motivated by the work of Saldin, Schneidmiller and Yurkov, we have measured the detuning curve widths, spectral characteristics, efficiency, and energy spread as a function of the taper for low and high Q resonators in the IR Demo FEL at Jefferson Lab. Both positive and negative tapers were used. Gain and frequency agreed surprisingly well with the predictions of a single mode theory. The efficiency agreed reasonably well for a negative taper with a high Q resonator but disagreed for lower Q values both due to the large slippage parameter and the non-ideal resonator Q. We saw better efficiency for a negative taper than for the same positive taper. The energy spread induced in the beam, normalized to the efficiency is larger for the positive taper than for the corresponding negative taper. This indicates that a negative taper is preferred over a positive taper in an energy recovery FEL.

  11. Zeeko precession for free-form polishing

    NASA Astrophysics Data System (ADS)

    Procháska, F.; Poláková, I.; Polák, J.; Matoušek, O.; Tomka, D.

    2016-11-01

    The aim of this work is an exploration of the options for optical surface polishing using the Zeeko IRP 100 machine and raster kinematics suitable for free-form polishing. For this purpose, aspheric surfaces were polished in raster prepolishing mode and then in Precession raster 3D shape correction, which is based on the Dwell time tool movement control. It was found that shape accuracy can achieve the value of approximately 35 nm RMS. The main inaccuracy was caused by the mid-spatial frequencies generated by the kinematics of the applied tools, which also limited the achievable values of microroughness.

  12. External validation of the medication taper complexity score for methadone tapers in children with opioid abstinence syndrome.

    PubMed

    Johnson, Peter N; Miller, Jamie L; Hagemann, Tracy M; Castro, Christine; Harrison, Donald

    2014-02-01

    Methadone is commonly prescribed for children with opioid abstinence syndrome (OAS) as a taper schedule over several days to weeks. The Medication Taper Complexity Score (MTCS) was developed to evaluate outpatient methadone tapers. To further validate the MTCS and determine if it is a reliable tool for clinicians to use to assess the complexity of methadone tapers for OAS. An expert panel of pediatric clinical pharmacists was convened. Panel members were provided 9 methadone tapers (ie, "easy," "medium," and "difficult") to determine construct and face validity of the MTCS. The primary objective was to further establish reliability and construct/face validity of the MTCS. The secondary objective was to assess the reliability of the MTCS within and between tapers. Instrument reliability was assessed using a Pearson correlation coefficient; with 0.8 as the minimum acceptable coefficient. Construct (divergent) validity was assessed via a repeated-measures ANOVA analysis (Bonferroni post hoc analyses) of the mean scores provided by panel members. Six panel members were recruited from various geographical locations. Panel members had 18.3 ± 5.5 years of experience, with practice expertise in general pediatrics, hematology/oncology, and the pediatric and neonatal intensive care unit. The MTCS had a reliability coefficient of .9949. There was vivid discrimination between the easy, medium, and difficult tapers; P = .001. The panel recommended minor modifications to the MTCS. The MTCS was found to be a reliable and valid tool. Overall, the panel felt that the MTCS was easy to use and had potential applications in both practice and research.

  13. [Mental health of Polish immigrants compared to that of the Polish and German populations].

    PubMed

    Morawa, Eva; Senf, Wolfgang; Erim, Yesim

    2013-01-01

    This survey examines the mental health of immigrants of Polish origin compared to samples from the Polish and German populations. In a sample of 513 subjects (261 persons with Polish migration background and 252 autochthone Poles) depression (BDI), anxiety (BAI), and somatic complaints (GBB-24) were measured. Immigrants of Polish origin showed a significantly higher level of anxiety as well as somatic complaints but only a tendency toward higher depressiveness than the German normvalue, but not than that of the native Poles. Female immigrants showed an overall higher number of symptoms in the three domains in question compared to German women and - except for depressiveness - also compared to male immigrants. Persons with a Polish migration background present levels of mental distress higher than the general German population, but similar to the population of their country of origin. Further research is needed to clarify the special structure of the mental morbidity in Polish immigrants.

  14. Macromodel for changes in polishing pad surface condition caused by dressing and polishing

    NASA Astrophysics Data System (ADS)

    Isobe, Akira; Ogata, Kenjiro; Kurokawa, Shuhei

    2014-01-01

    A macromodel for changes in a pad surface by dressing and polishing is proposed. A polishing pad is divided into small areas and it is assumed that each area takes an “H” (= high) or “L” (= low) condition. The condition is changed by dressing or polishing, and the total chemical mechanical planarization (CMP) performance is determined by the average pad condition. The results from equations are compared with experimental data, and good correspondence is confirmed. Various CMP behaviors are well explained by the equations, such as polishing rate stabilization by dummy running, the differences in the stability time and polishing rate between in situ dressing and ex situ dressing, and polishing rate behaviors for patterned wafers. This new model can be used to predict process performances, to optimize process conditions, or to indicate the direction of consumable development.

  15. Tapered Implants in Dentistry: Revitalizing Concepts with Technology: A Review.

    PubMed

    Wilson, T G; Miller, R J; Trushkowsky, R; Dard, M

    2016-03-01

    The most common approach to lessen treatment times is by decreasing the healing period during which osseointegration is established. Implant design parameters such as implant surface, primary stability, thread configuration, body shape, and the type of bone have to be considered to obtain this objective. The relationship that exists between these components will define the initial stability of the implant. It is believed implant sites using a tapered design and surface modification can increase the primary stability in low-density bone. Furthermore, recent experimental preclinical work has shown the possibility of attaining primary stability of immediately loaded, tapered dental implants without compromising healing and rapid bone formation while minimizing the implant stability loss at compression sites. This may be of singular importance with immediate/early functional loading of single implants placed in poor-quality bone. The selection of an implant that will provide adequate stability in bone of poor quality is important. A tapered-screw implant design will provide adequate stability because it creates pressure on cortical bone in areas of reduced bone quality. Building on the success of traditional tapered implant therapy, newer tapered implant designs should aim to maximize the clinical outcome by implementing new technologies with adapted clinical workflows. © International & American Associations for Dental Research 2016.

  16. In vitro corrosion testing of modular hip tapers.

    PubMed

    Goldberg, Jay R; Gilbert, Jeremy L

    2003-02-15

    The in vivo fretting behavior of modular hip prostheses was simulated to determine the effects of material combination and a unique TiN/AlN coating on fretting and corrosion at the taper interface. Fretting current, open-circuit potential (OCP), and quantities of soluble debris were measured to determine the role of mechanically assisted crevice corrosion on fretting and corrosion of modular hip tapers. Test groups consisting of similar-alloy (Co-Cr-Mo head/Co-Cr-Mo neck), mixed-alloy (Co-Cr-Mo head/Ti-6Al-4V neck), and TiN/AlN-coated mixed-alloy modular hip taper couples were used. Loads required to initiate fretting were similar for all test groups and were well below loads produced by walking and other physical activities. Decreases in OCP and increases in fretting current observed during long-term cyclic loading were indicative of fretting and corrosion. Current measured after cessation of cyclic loading suggests that once the conditions for crevice corrosion are established, corrosion can continue in the absence of loading. The chemical, mechanical, and electrochemical measurements, along with microscopic inspections of the taper surfaces indicate that the fretting and corrosion behavior of similar- and mixed-alloy taper couples are similar and that the coated samples are more resistant to fretting and corrosion. The results of this study clearly indicate the role of mechanical loading in the corrosion process, and support the hypothesis of mechanically assisted crevice corrosion.

  17. Temperature distribution and scuffing of tapered roller bearing

    NASA Astrophysics Data System (ADS)

    Wang, Ailin; Wang, Jiugen

    2014-11-01

    In the field of aerospace, high-speed trains and automobile, etc, analysis of temperature filed and scuffing failure of tapered roller bearings are more important than ever, and the scuffing failure of elements of such rolling bearings under heavy load and high speed still cannot be effectively predicted yet. A simplified model of tapered roller bearings consisted of one inner raceway, one outer raceway and a tapered roller was established, in which the interaction of several heat sources is ignored. The contact mechanics model, temperature model and model of scuffing failure are synthesized, and the corresponding computer programs are developed to analyze the effects of bearings parameters, different material and operational conditions on thermal performance of bearings, and temperature distribution and the possibility of surface scuffing are obtained. The results show that load, speed, thermal conductivity and tapered roller materials influence temperature rise and scuffing failure of bearings. Ceramic material of tapered roller results in the decrease of scuffing possibility of bearings to a high extent than the conventional rolling bearing steel. Compared with bulk temperature, flash temperature on the surfaces of bearing elements has a little influence on maximum temperature rise of bearing elements. For the rolling bearings operated under high speed and heavy load, this paper proposes a method which can accurately calculate the possibility of scuffing failure of rolling bearings.

  18. Modeling and multidimensional optimization of a tapered free electron laser

    NASA Astrophysics Data System (ADS)

    Jiao, Y.; Wu, J.; Cai, Y.; Chao, A. W.; Fawley, W. M.; Frisch, J.; Huang, Z.; Nuhn, H.-D.; Pellegrini, C.; Reiche, S.

    2012-05-01

    Energy extraction efficiency of a free electron laser (FEL) can be greatly increased using a tapered undulator and self-seeding. However, the extraction rate is limited by various effects that eventually lead to saturation of the peak intensity and power. To better understand these effects, we develop a model extending the Kroll-Morton-Rosenbluth, one-dimensional theory to include the physics of diffraction, optical guiding, and radially resolved particle trapping. The predictions of the model agree well with that of the GENESIS single-frequency numerical simulations. In particular, we discuss the evolution of the electron-radiation interaction along the tapered undulator and show that the decreasing of refractive guiding is the major cause of the efficiency reduction, particle detrapping, and then saturation of the radiation power. With this understanding, we develop a multidimensional optimization scheme based on GENESIS simulations to increase the energy extraction efficiency via an improved taper profile and variation in electron beam radius. We present optimization results for hard x-ray tapered FELs, and the dependence of the maximum extractable radiation power on various parameters of the initial electron beam, radiation field, and the undulator system. We also study the effect of the sideband growth in a tapered FEL. Such growth induces increased particle detrapping and thus decreased refractive guiding that together strongly limit the overall energy extraction efficiency.

  19. Chemical mechanical polishing of freestanding GaN substrates

    NASA Astrophysics Data System (ADS)

    Huaiyue, Yan; Xiangqian, Xiu; Zhanhui, Liu; Rong, Zhang; Xuemei, Hua; Zili, Xie; Ping, Han; Yi, Shi; Youdou, Zheng

    2009-02-01

    Chemical mechanical polishing (CMP) has been used to produce smooth and scratch-free surfaces for GaN. In the aqueous solution of KOH, GaN is subjected to etching. At the same time, all surface irregularities, including etch pyramids, roughness after mechanical polishing and so on will be removed by a polishing pad. The experiments had been performed under the condition of different abrasive particle sizes of the polishing pad. Also the polishing results for different polishing times are analyzed, and chemical mechanical polishing resulted in an average root mean square (RMS) surface roughness of 0.565 nm, as measured by atomic force microscopy.

  20. The influence of contact conditions and micromotions on the fretting behavior of modular titanium alloy taper connections.

    PubMed

    Baxmann, M; Jauch, S Y; Schilling, C; Blömer, W; Grupp, T M; Morlock, M M

    2013-05-01

    Modularity of femoral stems and neck components has become a more frequently used tool for an optimized restoration of the hip joint center and improvement of patient biomechanics. The additional taper interface increases the risk of mechanical failure due to fretting and crevice corrosion. Several failures of titanium alloy neck adapters have been documented in case-reports. An experimental fretting device was developed in this study to systematically investigate the effect of micromotion and contact pressure on fretting damage in contact situations similar to taper interfaces of modular hip prostheses under cyclic loading representative of in vivo load conditions. As a first application, the fretting behavior of Ti-6Al-4V titanium alloy components was investigated. Micromotions were varied between 10μm and 50μm, maximum contact pressures between 400 and 860N/mm(2). All modes of fretting damage were observed: Fretting wear was found for high micromotions in combination with low contact pressures. Fretting fatigue occurred with reduced movement or increased contact pressures. With small micromotions or high normal pressures, low fretting damage was observed. The developed device can be used to evaluate taper design (and especially contact geometry) as well as different materials prior to clinical use.

  1. Is there material loss at the backside taper in modular CoCr acetabular liners?

    PubMed

    Agne, Matthias T; Underwood, Richard J; Kocagoz, Sevi B; MacDonald, Daniel W; Day, Judd S; Parvizi, Javad; Kraay, Matthew J; Mont, Michael A; Klein, Gregg R; Cates, Harold E; Kurtz, Steven M

    2015-01-01

    Metal wear and corrosion products generated by hip replacements have been linked to adverse local tissue reactions. Recent investigations of the stem/head taper junction have identified this modular interface as another possible source of metal debris; however, little is known regarding other modular metallic interfaces, their ability to produce metal debris, and possibly to provide insight in the mechanisms that produce metal debris. We asked three questions: (1) can we develop a reliable method to estimate volumetric material loss from the backside taper of modular metal-on-metal liners, (2) do backside tapers of modular metal-on-metal liners show a quantifiable volumetric material loss, and, if so, (3) how do regions of quantitatively identified material loss correspond to visual and microscopic investigations of surface damage? Twenty-one cobalt-chromium (CoCr) liners of one design and manufacturer were collected through an institutional review board-approved retrieval program. All liners were collected during revision surgeries, where the primary revision reason was loosening (n=11). A roundness machine measured 144 axial profiles equally spaced about the circumference of the taper region near the rim to estimate volume and depth of material loss. Sensitivity and repeatability analyses were performed. Additionally, visual and scanning electron microscopy investigations were done for three liners. Our measurement method was found to be reproducible. The sensitivity (how dependent measurement results are on experimental parameters) and repeatability (how consistent results are between measurements) analyses confirmed that component alignment had no apparent effect (weak correlation, R2=0.04) on estimated volumetric material loss calculations. Liners were shown to have a quantifiable material loss (maximum=1.7 mm3). Visual investigations of the liner surface could identify pristine surfaces as as-manufactured regions, but could misidentify discoloration as a

  2. Polish women's experiences of breastfeeding in Ireland.

    PubMed

    Szafranska, Marcelina; Gallagher, Louise

    2016-01-01

    Exclusive breastfeeding among Polish mothers at three-four months (38.6 per cent) is in keeping with the low rates of breastfeeding in Ireland overall (Begley et al 2008), and suggests that Polish women have begun to adopt the infant feeding practices of Irish women. Therefore, the aim of this study was to explore the factors that influence Polish women's decisions to initiate and continue breastfeeding in Ireland. A descriptive qualitative approach was utilised to explore participants' perspectives of breastfeeding. Results showed that professional and family support are key to a successful breastfeeding experience for these mothers. Recommendations include further individualised support in order to meet the needs of Polish women breastfeeding in Ireland.

  3. Deterministic polishing from theory to practice

    NASA Astrophysics Data System (ADS)

    Hooper, Abigail R.; Hoffmann, Nathan N.; Sarkas, Harry W.; Escolas, John; Hobbs, Zachary

    2015-10-01

    Improving predictability in optical fabrication can go a long way towards increasing profit margins and maintaining a competitive edge in an economic environment where pressure is mounting for optical manufacturers to cut costs. A major source of hidden cost is rework - the share of production that does not meet specification in the first pass through the polishing equipment. Rework substantially adds to the part's processing and labor costs as well as bottlenecks in production lines and frustration for managers, operators and customers. The polishing process consists of several interacting variables including: glass type, polishing pads, machine type, RPM, downforce, slurry type, baume level and even the operators themselves. Adjusting the process to get every variable under control while operating in a robust space can not only provide a deterministic polishing process which improves profitability but also produces a higher quality optic.

  4. Polishing X-ray Mirror Mandrel

    NASA Technical Reports Server (NTRS)

    1999-01-01

    NASA's Space Optics Manufacturing Center has been working to expand our view of the universe via sophisticated new telescopes. The Optics Center's goal is to develop low-cost, advanced space optics technologies for the NASA program in the 21st century - including the long-term goal of imaging Earth-like planets in distant solar systems. To reduce the cost of mirror fabrication, Marshall Space Flight Center (MSFC) has developed replication techniques, the machinery, and materials to replicate electro-formed nickel mirrors. The process allows fabricating precisely shaped mandrels to be used and reused as masters for replicating high-quality mirrors. MSFC's Space Optics Manufacturing Technology Center (SOMTC) has grinding and polishing equipment ranging from conventional spindles to custom-designed polishers. These capabilities allow us to grind precisely and polish a variety of optical devices, including x-ray mirror mandrels. This image shows Charlie Griffith polishing the half-meter mandrel at SOMTC.

  5. Polishing X-ray Mirror Mandrel

    NASA Technical Reports Server (NTRS)

    1999-01-01

    NASA's Space Optics Manufacturing Center has been working to expand our view of the universe via sophisticated new telescopes. The Optics Center's goal is to develop low-cost, advanced space optics technologies for the NASA program in the 21st century - including the long-term goal of imaging Earth-like planets in distant solar systems. To reduce the cost of mirror fabrication, Marshall Space Flight Center (MSFC) has developed replication techniques, the machinery, and materials to replicate electro-formed nickel mirrors. The process allows fabricating precisely shaped mandrels to be used and reused as masters for replicating high-quality mirrors. MSFC's Space Optics Manufacturing Technology Center (SOMTC) has grinding and polishing equipment ranging from conventional spindles to custom-designed polishers. These capabilities allow us to grind precisely and polish a variety of optical devices, including x-ray mirror mandrels. This image shows Charlie Griffith polishing the half-meter mandrel at SOMTC.

  6. The Crisis of Polish Higher Education.

    ERIC Educational Resources Information Center

    Piasek, Ryszard; Vaughan, Michalina

    1987-01-01

    A discussion of recent declining enrollment in Polish higher education looks at the underlying demographic, economic, social, and policy factors causing changes in higher education in general, in specific institutions and faculties, and in women's participation. (MSE)

  7. Confinement loss in adiabatic photonic crystal fiber tapers

    NASA Astrophysics Data System (ADS)

    Kuhlmey, Boris T.; Nguyen, Hong C.; Steel, M. J.; Eggleton, Benjamin J.

    2006-09-01

    We numerically study confinement loss in photonic crystal fiber (PCF) tapers and compare our results with previously published experimental data. Agreement between theory and experiment requires taking into account hole shrinkage during the tapering process, which we measure by using a noninvasive technique. We show that losses are fully explained within the adiabatic approximation and that they are closely linked to the existence of a fundamental core-mode cutoff. This cutoff is equivalent to the core-mode cutoff in depressed-cladding fibers, so that losses in PCF tapers can be obtained semiquantitatively from an equivalent depressed-cladding fiber model. Finally, we discuss the definition of adiabaticity in this open boundary problem.

  8. Tapered rib fiber coupler for semiconductor optical devices

    DOEpatents

    Vawter, Gregory A.; Smith, Robert Edward

    2001-01-01

    A monolithic tapered rib waveguide for transformation of the spot size of light between a semiconductor optical device and an optical fiber or from the fiber into the optical device. The tapered rib waveguide is integrated into the guiding rib atop a cutoff mesa type semiconductor device such as an expanded mode optical modulator or and expanded mode laser. The tapered rib acts to force the guided light down into the mesa structure of the semiconductor optical device instead of being bound to the interface between the bottom of the guiding rib and the top of the cutoff mesa. The single mode light leaving or entering the output face of the mesa structure then can couple to the optical fiber at coupling losses of 1.0 dB or less.

  9. Optical Tapers as White-Light WGM Resonators

    NASA Technical Reports Server (NTRS)

    Strekalov, Dmitry V.; Matsko, Andrey B.; Savchenkov, Anatoliy A.

    2010-01-01

    A theoretical analysis has revealed that tapered optical waveguides could be useful as white-light whispering-gallery-mode (WGM) optical resonators. The compactness and the fixed-narrow-frequency-band nature of the resonances of prior microdisk and microsphere WGM resonators are advantageous in low-power, fixed-narrow-frequency-band applications. However for optical-processing applications in which there are requirements for power levels higher and/or spectral responses broader than those of prior microdisk and microsphere WGM resonators, white-light WGM resonators in the form of optical tapers would be preferable. The theoretical analysis was performed for a multimode, axisymmetric, circular-cross-section waveguide having a taper sufficiently smooth and gradual to justify the approximation of adiabaticity. In this approximation, the equation for the dependence of the electromagnetic field upon the axial (longitudinal) waveguide coordinate can be separated from the equation for the dependence upon the radius and the azimuthal angle.

  10. Misalignment tolerant efficient inverse taper coupler for silicon waveguide

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Michael, Aron; Kwok, Chee Yee; Chen, Ssu-Han

    2015-12-01

    This paper describes an efficient fiber to submicron silicon waveguide coupling based on an inversely tapered silicon waveguide embedded in a SiO2 waveguide that is suspended in air. The inverse taper waveguide consist of a 50um long and 240nm thick silicon that linearly taper in width from 500nm to 120nm, which is embedded in SiO2. The SiO2 waveguide is 6um wide and 10um long. The simulation results show that the coupling loss of this new approach is 2.7dB including the interface loss at the input and output. The tolerance to fiber misalignment at the input of the coupler is 2um in both horizontal and vertical directions for only 1.5dB additional loss.

  11. Attack polish for nickel-base alloys and stainless steels

    DOEpatents

    Not Available

    1980-05-28

    A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels is described. The chemical attack polich comprises FeNO/sub 3/, concentrated CH/sub 3/COOH, concentrated H/sub 2/SO/sub 4/ and H/sub 2/O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

  12. Wind-tunnel research comparing lateral control devices, particularly at high angles of attack IX : tapered wings with ordinary ailerons

    NASA Technical Reports Server (NTRS)

    Weick, Fred E; Wenzinger, Carl J

    1933-01-01

    Tests were made with ordinary flap-type ailerons on two wings with different amounts of taper, one medium and the other extreme. On each wing both medium sized tapered ailerons and short wide tapered ailerons were tested.

  13. Gap and channeled plasmons in tapered grooves: a review

    NASA Astrophysics Data System (ADS)

    Smith, C. L. C.; Stenger, N.; Kristensen, A.; Mortensen, N. A.; Bozhevolnyi, S. I.

    2015-05-01

    Tapered metallic grooves have been shown to support plasmons - electromagnetically coupled oscillations of free electrons at metal-dielectric interfaces - across a variety of configurations and V-like profiles. Such plasmons may be divided into two categories: gap-surface plasmons (GSPs) that are confined laterally between the tapered groove sidewalls and propagate either along the groove axis or normal to the planar surface, and channeled plasmon polaritons (CPPs) that occupy the tapered groove profile and propagate exclusively along the groove axis. Both GSPs and CPPs exhibit an assortment of unique properties that are highly suited to a broad range of cutting-edge nanoplasmonic technologies, including ultracompact photonic circuits, quantum-optics components, enhanced lab-on-a-chip devices, efficient light-absorbing surfaces and advanced optical filters, while additionally affording a niche platform to explore the fundamental science of plasmon excitations and their interactions. In this Review, we provide a research status update of plasmons in tapered grooves, starting with a presentation of the theory and important features of GSPs and CPPs, and follow with an overview of the broad range of applications they enable or improve. We cover the techniques that can fabricate tapered groove structures, in particular highlighting wafer-scale production methods, and outline the various photon- and electron-based approaches that can be used to launch and study GSPs and CPPs. We conclude with a discussion of the challenges that remain for further developing plasmonic tapered-groove devices, and consider the future directions offered by this select yet potentially far-reaching topic area.

  14. Single muscle fiber gene expression with run taper.

    PubMed

    Murach, Kevin; Raue, Ulrika; Wilkerson, Brittany; Minchev, Kiril; Jemiolo, Bozena; Bagley, James; Luden, Nicholas; Trappe, Scott

    2014-01-01

    This study evaluated gene expression changes in gastrocnemius slow-twitch myosin heavy chain I (MHC I) and fast-twitch (MHC IIa) muscle fibers of collegiate cross-country runners (n = 6, 20±1 y, VO₂max = 70±1 ml•kg-1•min-1) during two distinct training phases. In a controlled environment, runners performed identical 8 kilometer runs (30:18±0:30 min:s, 89±1% HRmax) while in heavy training (∼72 km/wk) and following a 3 wk taper. Training volume during the taper leading into peak competition was reduced ∼50% which resulted in improved race times and greater cross-section and improved function of MHC IIa fibers. Single muscle fibers were isolated from pre and 4 hour post run biopsies in heavily trained and tapered states to examine the dynamic acute exercise response of the growth-related genes Fibroblast growth factor-inducible 14 (FN14), Myostatin (MSTN), Heat shock protein 72 (HSP72), Muscle ring-finger protein-1 (MURF1), Myogenic factor 6 (MRF4), and Insulin-like growth factor 1 (IGF1) via qPCR. FN14 increased 4.3-fold in MHC IIa fibers with exercise in the tapered state (P<0.05). MSTN was suppressed with exercise in both fiber types and training states (P<0.05) while MURF1 and HSP72 responded to running in MHC IIa and I fibers, respectively, regardless of training state (P<0.05). Robust induction of FN14 (previously shown to strongly correlate with hypertrophy) and greater overall transcriptional flexibility with exercise in the tapered state provides an initial molecular basis for fast-twitch muscle fiber performance gains previously observed after taper in competitive endurance athletes.

  15. Laser polishing of additive manufactured Ti alloys

    NASA Astrophysics Data System (ADS)

    Ma, C. P.; Guan, Y. C.; Zhou, W.

    2017-06-01

    Laser-based additive manufacturing has attracted much attention as a promising 3D printing method for metallic components in recent years. However, surface roughness of additive manufactured components has been considered as a challenge to achieve high performance. In this work, we demonstrate the capability of fiber laser in polishing rough surface of additive manufactured Ti-based alloys as Ti-6Al-4V and TC11. Both as-received surface and laser-polished surfaces as well as cross-section subsurfaces were analyzed carefully by White-Light Interference, Confocal Microscope, Focus Ion Beam, Scanning Electron Microscopy, Energy Dispersive Spectrometer, and X-ray Diffraction. Results revealed that as-received Ti-based alloys with surface roughness more than 5 μm could be reduce to less than 1 μm through laser polishing process. Moreover, microstructure, microhardness and wear resistance of laser-polished zone was investigated in order to examine the thermal effect of laser polishing processing on the substrate of additive manufactured Ti alloys. This proof-of-concept process has the potential to effectively improve the surface roughness of additive manufactured metallic alloy by local polishing method without damage to the substrate.

  16. Transverse Wakefields from Tapered Collimators: Measurements and Analysis

    SciTech Connect

    Tenenbaum, Peter G

    2001-07-27

    We report on a series of measurements of the transverse wakefield from tapered collimators. The collimators were designed to principally present a geometric impedance to the beam, and to minimize impedances from resistivity or surface features; in addition, the geometries of the collimators were selected to permit examination of the scaling behavior of the wakefield due to collimator taper angle and minimum gap size. We present the measured near-center wakefields of the collimators, as well as the effect of bunch-length variation. The measurements are compared to analytic models and MAFIA simulations.

  17. Bent optical fiber tapers for refractometery and biosensing

    NASA Astrophysics Data System (ADS)

    Penchev, Emil; Eftimov, Tinko; Bock, Wojtek

    2015-01-01

    We report the results of our study of the spectral shifts caused by surrounding refractive index changes (SRI) in bent fibre tapers. Fused and etched fibre tapers were fabricated using a gas burner and HF acid. Spectral shifts as high as 200 nm have been observed for SRI variations from 1.33 to 1.44 and sensitivity as high as 830 nm/r.i.u. around water RI values. We present results for refractometric measurements of cow milk of varying fat content and compare results with those obtained with conventional Abbe refractometers and high sensitivity double resonance LPGs.

  18. Impedance Scaling for Small-angle Tapers and Collimators

    SciTech Connect

    Stupakov, G.; /SLAC

    2010-02-11

    In this note I will prove that the impedance calculated for a small-angle collimator or taper, of arbitrary 3D profile, has a scaling property that can greatly simplify numerical calculations. This proof is based on the parabolic equation approach to solving Maxwell's equation developed in Refs. [1, 2]. We start from the parabolic equation formulated in [3]. As discussed in [1], in general case this equation is valid for frequencies {omega} >> c/a where a is a characteristic dimension of the obstacle. However, for small-angle tapers and collimators, the region of validity of this equation extends toward smaller frequencies and includes {omega} {approx} c/a.

  19. The Frequency of Torsional Vibration of a Tapered Beam

    NASA Technical Reports Server (NTRS)

    Coleman, Robert

    1939-01-01

    A solution for the equation of torsional vibration of tapered beams has been found in terms of Bessel functions for beams satisfying the following conditions: (a) the cross sections along the span are similar in shape; and (b) the torsional stiffness of a section can be expressed as a power of a linear function of distance along the span. The method of applying the analysis to actual cases has been described. Charts are given from which numerical values can be immediately obtained for most cases of practical importance. The theoretical values of the frequency ratio have been experimentally checked on five beams having different amounts of taper.

  20. Optimised process for fabricating tapered long period gratings

    NASA Astrophysics Data System (ADS)

    Mullaney, K.; Staines, S. E.; James, S. W.; Tatam, R. P.

    2017-04-01

    The process of fabricating tapered long period gratings (TLPGs) using a CO2 laser is described. TLPGs with a period spacing of 378 μm, were fabricated by optimization of the taper waist diameter and careful control of the duty-cycle and its uniformity along the length of the grating. The 6-period TLPGs exhibited a pass-band insertion loss of 0.6 dB, resonance band extinction values of 3 dB and had a physical length of 2.27 mm.

  1. Technology Development for Tapered-Wiggler Free-Electron Lasers

    DTIC Science & Technology

    1984-04-01

    canting can produce equal e-beam focusing in each of the two - transverse directions. Thus the e-beam focusing characteristics of a helical wiggler can...Both taper prescriptions require a modest frequency chirp of less than 1.5 percent during start-up. 3.2 VARIALE -TAPER WIGGLER EMAWQEM DEVEPHE T This...with Nonuniform Wigglers," IEEE J. Quantum Electron. QE-16, 335 (1980). 4-8. J.P. Blewett and R. Chasman, "Orbits and Fields in the Helical Wiggler," J

  2. Opioid abstinence reinforcement delays heroin lapse during buprenorphine dose tapering.

    PubMed

    Greenwald, Mark K

    2008-01-01

    A positive reinforcement contingency increased opioid abstinence during outpatient dose tapering (4, 2, then 0 mg/day during Weeks 1 through 3) in non-treatment-seeking heroin-dependent volunteers who had been maintained on buprenorphine (8 mg/day) during an inpatient research protocol. The control group (n=12) received $4.00 for completing assessments at each thrice-weekly visit during dose tapering; 10 of 12 lapsed to heroin use 1 day after discharge. The abstinence reinforcement group (n=10) received $30.00 for each consecutive opioid-free urine sample; this significantly delayed heroin lapse (median, 15 days).

  3. Fabrication and characterization of bare Ge-Sb-Se chalcogenide glass fiber taper

    NASA Astrophysics Data System (ADS)

    Luo, Baohua; Wang, Yingying; Sun, Ya'nan; Dai, Shixun; Yang, Peilong; Zhang, Peiqing; Wang, Xunsi; Chen, Feifei; Wang, Rongping

    2017-01-01

    In this work, Ge15Sb20Se65 bare glass fiber with a diameter of 500 μm was fabricated, and then tapered with different tapering parameters. The analysis of Raman and energy dispersive X-ray spectra (EDS) indicated that, a slight change in the chemical composition of the glass, fiber and tapering fiber has negligible effect on the glass structure. It was found that, the waist diameter decreases exponentially with increasing tapering length and speed, and high quality taper fiber with the cone diameter of 2.65 μm can be achieved under the optimal tapering conditions. Finally, the simulated and experimental results of the output transmission under different waist length and taper ratio show that the transmission decreases with increasing waist length and taper ratio.

  4. Experimental Investigation of Superradiance in a Tapered Free-Electron Laser Amplifier

    SciTech Connect

    Hidaka, Y.; She, Y.; Murphy, J.B.; Podobedov, B.; Seletskiy, S.; Yang, X.

    2011-03-28

    We report experimental studies of the effect of undulator tapering on superradiance in a single-pass high-gain free-electron laser (FEL) amplifier. The experiments were performed at the Source Development Laboratory (SDL) of National Synchrotron Light Source (NSLS). Efficiency was nearly tripled with tapering. Both the temporal and spectral properties of the superradiant FEL along the uniform and tapered undulator were experimentally characterized using frequency-resolved optical gating (FROG) images. Numerical studies predicted pulse broadening and spectral cleaning by undulator tapering Pulse broadening was experimentally verified. However, spectral cleanliness degraded with tapering. We have performed first experiments with a tapered undulator and a short seed laser pulse. Pulse broadening with tapering expected from simulations was experimentally confirmed. However, the experimentally obtained spectra degraded with tapering, whereas the simulations predicted improvement. A further numerical study is under way to resolve this issue.

  5. Efficient sub-wavelength light confinement using surface plasmon polaritons in tapered fibers.

    PubMed

    Renna, Fabrizio; Cox, David; Brambilla, Gilberto

    2009-04-27

    Light confinement to sub-wavelength spot sizes is proposed and realized in tapered optical fibers. To achieve high transmission efficiencies, light propagating along the taper is combined with the excitation of surface plasmon polaritons (SPP) at its tip.

  6. Tapered plasma channels to phase-lock accelerating and focusing forces in laser-plasma accelerators

    SciTech Connect

    Rittershofer, W.; Schroeder, C.B.; Esarey, E.; Gruner, F.J.; Leemans, W.P.

    2010-05-17

    Tapered plasma channels are considered for controlling dephasing of a beam with respect to a plasma wave driven by a weakly-relativistic, short-pulse laser. Tapering allows for enhanced energy gain in a single laser plasma accelerator stage. Expressions are derived for the taper, or longitudinal plasma density variation, required to maintain a beam at a constant phase in the longitudinal and/or transverse fields of the plasma wave. In a plasma channel, the phase velocities of the longitudinal and transverse fields differ, and, hence, the required tapering differs. The length over which the tapered plasma density becomes singular is calculated. Linear plasma tapering as well as discontinuous plasma tapering, which moves beams to adjacent plasma wave buckets, are also considered. The energy gain of an accelerated electron in a tapered laser-plasma accelerator is calculated and the laser pulse length to optimize the energy gain is determined.

  7. Effects of taper on drilling and cutting with a pulsed laser

    NASA Astrophysics Data System (ADS)

    Angell, James; Ho, Wen; Schaeffer, Ronald D.

    1997-04-01

    An inherent characteristic of laser machined features is taper. For a particular laser the degree of taper is largely dependent on two things: the type of material being machined and the laser energy per unit area or fluence at the processing surface. The latter of these is dependent on different parameters for the three lasers mentioned above. In this paper we review the particular laser parameters that control taper and what degree of taper can be expected for certain materials. More often than not taper is a nondesirable characteristic and is, in many cases, the limiting factor regarding the maximum thickness of material that a laser is practically capable of drilling or cutting through. We therefore discuss methods of minimizing taper and its effects. Under some circumstances taper can be used to one's advantage to achieve a desired feature size if one has control over the taper angle.

  8. Effects of taper on drilling and cutting with a pulsed laser

    NASA Astrophysics Data System (ADS)

    Angell, James; Ho, Wen; Schaeffer, Ronald D.

    1997-03-01

    An inherent characteristic of laser machined features is taper. For a particular laser the degree of taper is largely dependent on two things: the type of material being machined and the laser energy per unit area or fluence at the processing surface. The latter of these is dependent on different parameters for the three lasers mentioned above. In this paper we review the particular laser parameters that control taper and what degree of taper can be expected for certain materials. More often than not taper is a nondesirable characteristic and is, in many cases, the limiting factor regarding the maximum thickness of material that a laser is practically capable of drilling or cutting through. We therefore discuss methods of minimizing taper and its effects. Under some circumstances taper can be used to one's advantage to achieve a desired feature size if one has control over the taper angle.

  9. Optimization of group delay response of (apodized) tapered fiber Bragg grating by shaping taper transition and apodization window

    NASA Astrophysics Data System (ADS)

    Markowski, Konrad; Jedrzejewski, Kazimierz; Osuch, Tomasz

    2016-09-01

    This article presents implementation of the Simulated Annealing (SA) algorithm for tapered fiber Bragg gratings (TFBGs) design. Particularly, together with well-known Coupled Mode Theory (CMT) and Transfer Matrix Method (TMM) the algorithm optimizes the group delay response of TFBG, by simultaneous shaping of both apodization function and tapered fiber transition profile. Prior to the optimization process, numerical model for TFBG design has been validated. Preliminary results reveal great potential of the SA-based approach and with proper definition of the design criteria may be even applied for optimization of the spectral properties of TFBGs.

  10. Design Considerations of Polishing Lap for Computer-Controlled Cylindrical Polishing Process

    NASA Technical Reports Server (NTRS)

    Khan, Gufran S.; Gubarev, Mikhail; Arnold, William; Ramsey, Brian D.

    2009-01-01

    This paper establishes a relationship between the polishing process parameters and the generation of mid spatial-frequency error. The consideration of the polishing lap design to optimize the process in order to keep residual errors to a minimum and optimization of the process (speeds, stroke, etc.) and to keep the residual mid spatial-frequency error to a minimum, is also presented.

  11. Internet Use of Polish by Polish Melburnians: Implications for Maintenance and Teaching

    ERIC Educational Resources Information Center

    Fitzgerald, Michael; Debski, Robert

    2006-01-01

    The Internet has become an important communication medium and it is having a significant impact on language use. The present study takes a "snapshot" of how the Polish language is currently used with modern communications technologies by Polish-Australians living in Melbourne. Through a questionnaire, it surveys which communications…

  12. Polish parliament liberalizes abortion law.

    PubMed

    1996-11-22

    On October 24, the Sejm (Poland's lower house of parliament) voted 228 to 195 (with 16 abstentions) to amend Poland's March 1993 ban on abortions. The amendment legalizes abortion until the 12th week of pregnancy for women who face financial hardship or difficult personal circumstances. Client counseling by a doctor who will not perform the abortion and a 3-day wait are required. Abortions will be permitted in licensed private clinics, as well as in public hospitals. Anyone performing an illegal abortion can receive 2 years' imprisonment. The government will subsidize contraceptive pills, and a sex education curriculum will be developed for schools. Abortion had been legal and widely available under communist rule; however, a Catholic-aligned government limited abortion to cases where a woman's life or health was endangered, where the pregnancy resulted from rape or incest, or where the fetus had a severe anomaly. The Catholic Church opposed the new measure, and the Senat (Poland's upper house), on October 3, had voted 40 to 52 (with 2 abstentions) against the amendment. Although the Sejm had previously voted 208 to 61 (with 15 abstentions) in favor of the amendment, 120 of those opposed to the measure, primarily members of the Polish Peasants Party (part of Poland's ruling coalition), had walked out in protest just before an August tally. The Democratic Left Alliance, the other coalition partner, supports the amendment. The most recent vote in the Sejm overturns the Senat veto; however, before the law can go into effect in 1997, it must be signed by President Aleksandr Kwasniewski (a supporter) after a review by Poland's conservative constitutional tribunal.

  13. New technology in condensate polishing

    SciTech Connect

    Kunin, R.; Salem, E.; Libutti, B. . Water Div.)

    1992-08-01

    Sulfonic acid ion exchange resins. when carried into a boiler or steam generator, thermally decompose releasing large amounts of corrosive, sulfates. Replacement of the sulfonic acid resin with a carboxylic acid resin would eliminate this source of contamination. The sulfonic acid resin is a strong acid: the carboxylic acid resin is a weak acid. The carboxylic acid resin alone is not capable of splitting salts which limits its use to mixed resin beds or to its use in single or individual beds with feeds of high alkalinity or high pH values. Laboratory, pilot plant and full scale plant tests compared the two resins in precoat filters. When the resins in mixed beds were in the acid form, the weakly acid resin was almost as effective in removing sodium ion as the strongly acid resin. In the ammonium form. the weakly acid resin was generally more effective in removing sodium than the strongly acid resin. Condensate polishing reduced the sodium ion to a few parts per billion (ppB). Complete resin separation before regeneration is more important for the weakly acid resin than for the strongly acid resin. Another development found that the hydrazine reaction with oxygen could be catalyzed by powdered activated carbon combined with microfibers on a Powdex substrate. The carbon should be thoroughly washed to reduce its residual sodium content. In plant tests, the carbon reduced the oxygen concentration in condensate about 50% during startup. In preliminary tests believed to be typical, carbon lowered the oxygen concentration below 10 ppB in about 6 hours compared to 18 hours without the carbon. Oxygen is also reduced during normal operation.

  14. Ultraviolet-extended flat supercontinuum generation in cascaded photonic crystal fiber tapers

    NASA Astrophysics Data System (ADS)

    Chen, H. H.; Chen, Z. L.; Zhou, X. F.; Hou, J.

    2013-08-01

    Cascaded photonic crystal fiber (PCF) tapers in a monolithic fiber obtained by post-processing techniques such as hole inflation and tapering have been manufactured. An ultraviolet-extended supercontinuum (SC) generation down to 352 nm wavelength pumped at 1064 nm in cascading PCF tapers has been obtained. High spectral flatness (5 dB) has been achieved in the entire visible window.

  15. Opioid Abstinence Reinforcement Delays Heroin Lapse during Buprenorphine Dose Tapering

    ERIC Educational Resources Information Center

    Greenwald, Mark K.

    2008-01-01

    A positive reinforcement contingency increased opioid abstinence during outpatient dose tapering (4, 2, then 0 mg/day during Weeks 1 through 3) in non-treatment-seeking heroin-dependent volunteers who had been maintained on buprenorphine (8 mg/day) during an inpatient research protocol. The control group (n = 12) received $4.00 for completing…

  16. Pulse Compression using a Tapered Microstructure Optical Fiber

    DTIC Science & Technology

    2006-04-01

    Pulse compression using a tapered microstructure optical fiber Jonathan Hu, Brian S. Marks, and Curtis R. Menyuk University of Maryland Baltimore...R. Menyuk , ”Optimization of the Split-Step Fourier Method in Modeling Optical-Fiber Communications Systems,” J. Lightwave Technol. 21, 61–68 (2003

  17. Temperature sensing characteristics of tapered Tm3+-doped fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Sanchez-Lara, R.; E Ceballos-Herrera, D.; Vazquez-Avila, J. L.; de la Cruz-May, L.; Martinez-Pinon, F.; Alvarez-Chavez, J. A.

    2017-08-01

    We numerically analyze the temperature response of a tapered Tm3+-doped fiber amplifier. The analysis includes a redefinition of the coupled pump and signal propagation equations in order to introduce different longitudinal shapes of the tapered doped fiber and the temperature dependence of the absorption and emission cross sections of the Tm3+ ions under different pump schemes. It was found that the temperature sensitivity of the normalized amplified signal was 2  ×  10-3/°C for 1 W of pump power and 3 m of doped fiber length, using a parabolic taper in a co-propagating pump scheme. This sensitivity can be increased by at least 5 times if we adjust the design parameters of the fiber amplifier using fiber lengths shorter than 1 m and pump powers lower than 300 mW. Our results contribute with new information for the development and optimization of tapered fiber amplifiers doped with other rare earths, and novel designs for doped-fiber temperature sensors.

  18. Tapered Roller Bearing Damage Detection Using Decision Fusion Analysis

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Kreider, Gary; Fichter, Thomas

    2006-01-01

    A diagnostic tool was developed for detecting fatigue damage of tapered roller bearings. Tapered roller bearings are used in helicopter transmissions and have potential for use in high bypass advanced gas turbine aircraft engines. A diagnostic tool was developed and evaluated experimentally by collecting oil debris data from failure progression tests conducted using health monitoring hardware. Failure progression tests were performed with tapered roller bearings under simulated engine load conditions. Tests were performed on one healthy bearing and three pre-damaged bearings. During each test, data from an on-line, in-line, inductance type oil debris sensor and three accelerometers were monitored and recorded for the occurrence of bearing failure. The bearing was removed and inspected periodically for damage progression throughout testing. Using data fusion techniques, two different monitoring technologies, oil debris analysis and vibration, were integrated into a health monitoring system for detecting bearing surface fatigue pitting damage. The data fusion diagnostic tool was evaluated during bearing failure progression tests under simulated engine load conditions. This integrated system showed improved detection of fatigue damage and health assessment of the tapered roller bearings as compared to using individual health monitoring technologies.

  19. Vibration frequencies of tapered bars with nonclassical boundary conditions

    NASA Technical Reports Server (NTRS)

    Craver, W. Lionel, Jr.

    1988-01-01

    The goals for this research were revised and clarified. The goals are restated along with an evaluation of the accomplishment of the goal. All of the cases of the truncated-cone beams that were originally proposed to be solved were solved. A summary of these solutions is presented. Some cases of beams with unequal tapers were solved and are discussed.

  20. Tapered optical fiber sensor for chemical pollutants detection in seawater

    NASA Astrophysics Data System (ADS)

    Irigoyen, Maite; Sánchez-Martin, Jose Antonio; Bernabeu, Eusebio; Zamora, Alba

    2017-04-01

    Three tapered silica optical fibers, uncoated and coated with metallic (Al or Cu) and dielectric layers (TiO2), are employed to determine the presence of oil and Hazardous and Noxious Substances (HNS from now on) in water, by means of the measurement of their spectral transmittance. With our experimental assembly, the presence of oil and HNS spills can be detected employing the three different kinds of tapers, since the complete range of refractive indices of the pollutants (1.329-1.501) is covered with these tapers. The most suitable spectral range to detect the presence of a chemical pollutant in seawater has been identified and a complete spectral characterization of the three types of optical fiber tapers has been carried out. The results obtained show that, in general terms, these devices working together can be employed for the early detection of oil and HNS spills in seawater in a marine industrial environment. These sensors have many advantages, such as its low cost, its simplicity and versatility (with interesting properties as quick response and repeatability), and especially that they can be self-cleaned with seawater in motion.

  1. Integrative Performance Analysis of a Novel Bone Level Tapered Implant.

    PubMed

    Dard, M; Kuehne, S; Obrecht, M; Grandin, M; Helfenstein, J; Pippenger, B E

    2016-03-01

    Primary mechanical stability, as measured by maximum insertion torque and resonance frequency analysis, is generally considered to be positively associated with successful secondary stability and implant success. Primary implant stability can be affected by several factors, including the quality and quantity of available bone, the implant design, and the surgical procedure. The use of a tapered implant design, for instance, has been shown to result in good primary stability even in clinical scenarios where primary stability is otherwise difficult to achieve with traditional cylindrical implants-for example, in soft bone and for immediate placement in extraction sockets. In this study, bone-type specific drill procedures are presented for a novel Straumann bone level tapered implant that ensure maximum insertion torque values are kept within the range of 15 to 80 Ncm. The drill procedures are tested in vitro using polyurethane foam blocks of variable density, ex vivo on explanted porcine ribs (bone type 3), and finally in vivo on porcine mandibles (bone type 1). In each test site, adapted drill procedures are found to achieve a good primary stability. These results are further translated into a finite element analysis model capable of predicting primary stability of tapered implants. In conclusion, we have assessed the biomechanical behavior of a novel taper-walled implant in combination with a bone-type specific drill procedure in both synthetic and natural bone of various types, and we have developed an in silico model for predicting primary stability upon implantation. © International & American Associations for Dental Research 2016.

  2. Strength of small-diameter round and tapered bending members

    Treesearch

    Ron Wolfe; Joe Murphy

    2005-01-01

    An early focus on structural use of processed rather than round timber resulted in an underestimation of the structural advantages of retaining the natural form of small-diameter round timber. In the round and tapered form, timbers are not susceptible to the strength-reducing effects of diving grain and exposed juvenile wood. Fiber continuity around knots on the...

  3. Taper and volume equations for selected Appalachian hardwood species

    Treesearch

    A. Jeff Martin

    1981-01-01

    Coefficients for five taper/volume models are developed for 18 Appalachian hardwood species. Each model can be used to estimate diameter at any point on the bole, height to any preselected diameter, and cubic-foot volume between any two points on the bole. The resulting equations were tested on six sets of independent data and an evaluation of these tests is included,...

  4. Impedance Matching of Tapered Slot Antenna using a Dielectric Transformer

    NASA Technical Reports Server (NTRS)

    Simons, R. N.; Lee, R. Q.

    1998-01-01

    A new impedance matching technique for tapered slot antennas using a dielectric transformer is presented. The technique is demonstrated by measuring the input impedance, Voltage Standing Wave Ratio (VSWR) and the gain of a Vivaldi antenna (VA). Measured results at Ka-Band frequencies are presented and discussed.

  5. Narcotic tapering in pregnancy using long-acting morphine

    PubMed Central

    Dooley, Roisin; Dooley, Joe; Antone, Irwin; Guilfoyle, John; Gerber-Finn, Lianne; Kakekagumick, Kara; Cromarty, Helen; Hopman, Wilma; Muileboom, Jill; Brunton, Nicole; Kelly, Len

    2015-01-01

    Abstract Objective To document the management of and outcomes for patients receiving narcotic replacement and tapering with long-acting morphine preparations during pregnancy. Design A prospective cohort study over 18 months. Setting Northwestern Ontario. Participants All 600 births at Meno Ya Win Health Centre in Sioux Lookout, Ont, from January 1, 2012, to June 30, 2013, including 166 narcotic-exposed pregnancies. Intervention Narcotic replacement and tapering of narcotic use with long-acting morphine preparations. Main outcome measures Prenatal management of maternal narcotic use, incidence of neonatal abstinence syndrome, and other neonatal outcomes. Results The incidence of neonatal abstinence syndrome fell significantly to 18.1% of pregnancies exposed to narcotics (from 29.5% in a previous 2010 study, P = .003) among patients using narcotic replacement and tapering with long-acting morphine preparations. Neonatal outcomes were otherwise equivalent to those of the nonexposed pregnancies. Conclusion In many patients, long-acting morphine preparations can be safely used and tapered in pregnancy, with a subsequent decrease in observed neonatal withdrawal symptoms. PMID:25821873

  6. Tapered fiber bundles for combining high-power diode lasers.

    PubMed

    Kosterin, Andrey; Temyanko, Valery; Fallahi, Mahmoud; Mansuripur, Masud

    2004-07-01

    Tapered fiber bundles are often used to combine the output power of several semiconductor lasers into a multimode optical fiber for the purpose of pumping fiber lasers and amplifiers. It is generally recognized that the brightness of such combiners does not exceed the brightness of the individual input fibers. We report that the brightness of the tapered fibers (and fiber bundles) depends on both the taper ratio and the mode-filling properties of the beams launched into the individual fibers. Brightness, therefore, can be increased by selection of sources that fill a small fraction of the input fiber's modal capacity. As proof of concept, we present the results of measurements on tapered fiber-bundle combiners having a low-output étendue. Under low mode-filling conditions per input multimode fiber (i.e., fraction of filled modes < or =0.29), we report brightness enhancements of 8.0 dB for 19 x 1 bundles, 6.7 dB for 7 x 1 bundles, and 4.0 dB for 3 x 1 combiners. Our measured coupling efficiency variations of approximately 1%-2% among the various fibers in a given bundle confirm the uniformity and quality of the fabricated devices.

  7. Northeastern FIA Tree Taper Study: Current Status and Future Work

    Treesearch

    James A. Westfall; Charles T. Scott

    2005-01-01

    The northeastern unit of the Forest Inventory and Analysis program (NE-FIA) is engaged in an ongoing project to develop regionwide tree taper equations. Sampling intensity is based on NE-FIA plot data and is stratified by species, diameter class, and height class. To date, modeling research has been aimed largely at evaluating existing model forms (and hybrids thereof...

  8. FSW of Tapered Thickness Welds using an Adjustable Pin Tool

    NASA Technical Reports Server (NTRS)

    Adams, Glynn; Venable, Richard; Lawless, Kirby; Smelser, Jerry (Technical Monitor)

    2002-01-01

    This viewgraph presentation describes the advantages of tapered thickness welds in FSW (friction stir welding), the structure of FSW welds, the adjustable pin tool used in FSW. Other topics described include compliance and temperature measurement in a FSW system, loads and torque upon the pin tool and its ability to penetrate different metals, and the results and metallurgy of FSW welds.

  9. Linearly tapered slot antenna circular array for mobile communications

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Kelly, Eron; Lee, Richard Q.; Taub, Susan R.

    1993-01-01

    The design, fabrication and testing of a conformal K-band circular array is presented. The array consists of sixteen linearly tapered slot antennas (LTSA). It is fed by a 1:16 microstrip line power splitter via electromagnetic coupling. The array has an omni-directional pattern in the azimuth plane. In the elevation plane the beam is displaced above the horizon.

  10. Efficiency optimization in a FEL with fields` nonadiabatic tapering

    SciTech Connect

    Goncharov, I.A.; Belyavskiy, E.D.; Silivra, A.A.

    1995-12-31

    Amplification of an electromagnetic wave in free electron lasers with a reversed guide field and right-hand polarized wiggler field is investigated both analytically and numerically. An effect of electron bunch trapping by the high frequency electromagnetic field is used for efficiency optimization. On the basis of motion stability criteria a possibility of bunches trapping by FEL parameters nonadiabatic (experimentally realizable) tapering is shown. The stability analysis of electron motion is based on Lyapunov theory for autonomy systems. A particle simulation is carried out for FEL parameters close to the experimental ones (relativistic factor {gamma}=4.75, wiggler field strength B{sub w}= 2.8 kG, guide field strength B{sub o}= -1.4 kG, operation wavelength {lambda}=6.2 mm) for the case of wiggler field tapering. Theoretically predicted rule of wiggler field tapering corresponding to FEL efficiency of 55% is approximated by stepped functions. For the experimentally realizable tapering it is found that FEL efficiency can be over 40%.

  11. Surface Roughness and Gloss of Actual Composites as Polished With Different Polishing Systems.

    PubMed

    Rodrigues-Junior, S A; Chemin, P; Piaia, P P; Ferracane, J L

    2015-01-01

    This in vitro study evaluated the effect of polishing with different polishing systems on the surface roughness and gloss of commercial composites. One hundred disk-shaped specimens (10 mm in diameter × 2 mm thick) were made with Filtek P-90, Filtek Z350 XT, Opallis, and Grandio. The specimens were manually finished with #400 sandpaper and polished by a single operator using three multistep systems (Superfix, Diamond Pro, and Sof-lex), one two-step system (Polidores DFL), and one one-step system (Enhance), following the manufacturer's instructions. The average surface roughness (μm) was measured with a surface profilometer (TR 200 Surface Roughness Tester), and gloss was measured using a small-area glossmeter (Novo-Curve, Rhopoint Instrumentation, East Sussex, UK). Data were analyzed by two-way analysis of variance and Tukey's test (α=0.05). Statistically significant differences in surface roughness were identified by varying the polishing systems (p<0.0001) and by the interaction between polishing system and composite (p<0.0001). Pairwise comparisons revealed higher surface roughness for Grandio when polished with Sof-Lex and Filtek Z250 and Opallis when polished with Enhance. Gloss was influenced by the composites (p<0.0001), the polishing systems (p<0.0001), and the interaction between them (p<0.0001). The one-step system, Enhance, produced the lowest gloss for all composites. Surface roughness and gloss were affected by composites and polishing systems. The interaction between both also influenced these surface characteristics, meaning that a single polishing system will not behave similarly for all composites. The multistep systems produced higher gloss, while the one-step system produced the highest surface roughness and the lowest gloss of all.

  12. STEM, STEM Education, STEMmania

    ERIC Educational Resources Information Center

    Sanders, Mark

    2009-01-01

    In this article, the author introduces integrative STEM (science, technology, engineering, and/or mathematics) education and discusses the importance of the program. The notion of integrative STEM education includes approaches that explore teaching and learning between/among any two or more of the STEM subject areas, and/or between a STEM subject…

  13. An evaluation of the effects of handpiece speed, abrasive characteristics, and polishing load on the flexural strength of polished ceramics.

    PubMed

    Ahmad, Rohana; Morgano, Steven M; Wu, Benjamin M; Giordano, Russell A

    2005-11-01

    Many studies on the strengthening effects of grinding and polishing, as well as heat treatment on ceramics, are not well standardized or use commercially available industrial polishing systems. The reported effectiveness of these strengthening mechanisms on ceramics may not be applicable to clinical dentistry. The purpose of this study was to evaluate the effects of controlled polishing on the flexural strength of dental ceramics by using a custom-made machine that applied standardized loads and speeds that coincided with the mean loads and speeds used by experienced prosthodontists. A total of 140 aluminous dental ceramic bar-shaped specimens (Vitadur Alpha Enamel) measuring 1.5 x 2.0 x 25 mm were fabricated and divided into 12 groups (for most groups, n=10). Specimens were untreated, polished with different polishing systems, polished at different speeds, ground and autoglazed, polished and autoglazed, autoglazed and polished, polished with loose (paste) and bonded abrasives, or overglazed. Simulated clinical polishing was performed on the ceramic specimens by using a customized polishing apparatus that allowed independent control over the relevant polishing parameters (abrasive hardness, applied load, linear speed, rotational velocity, and wheel stiffness). Flexural strength (MPa) was measured with a 4-point bending test, and subjective surface roughness was assessed with scanning electron microscopy. Autoglazing was performed at various stages of the polishing sequence to determine the effects of polishing on surface stresses. Mean values, standard deviations, independent-sample t tests, 1-way and 2-way analyses of variance, Dunnett t tests and Kruskal-Wallis tests were applied to the data (alpha=.05). Under a clinical load of 0.6 N for a coarse polishing wheel, 1.0 N for a medium polishing wheel, and 1.3 N for a fine polishing wheel, a linear speed of 499 mm/min, and a rotational velocity of 10,000 rpm, the use of clinical polishing instruments did not affect

  14. Intensive management influence on Douglas-fir stem form, branch characteristics, and simulated product recovery

    Treesearch

    A.R. Weiskittel; R.A. Monserud; R. Rose; E.C. Turnblom; Douglas A. Maguire

    2006-01-01

    Intensive management may adversely affect lumber yield and quality by increasing knot size and creating a more conical stem form with a greater average rate of taper. This study was initiated to examine the impact of management on simulated lumber yield and quality. Stem diameter and branch size and location of 223 Pseudotsuga menziesii (Mirb.)...

  15. Modeling stem profile of Triadica Sebifera in southern forestlands of Mississippi

    Treesearch

    Nana Tian; Zhaofei Fan

    2016-01-01

    Chinese tallow (Triadica sebifera) is one of the most aggressive invasive species in the southern forestlands of United States. To explore the stem taper of tallow, outside-and-inside bark stem profile equations were fitted using Max and Burkhart (1976), Cao (2009) modified Max and Burkhart, andClark, Souter, and Schlaegel (1991) segmented...

  16. Basal area increment and growth efficiency as functions of canopy dynamics and stem mechanics

    Treesearch

    Thomas J. Dean

    2004-01-01

    Crown and canopy structurecorrelate with growth efficiency and also determine stem size and taper as described by the uniform stress principle of stem formation. A regression model was derived from this principle that expresses basal area increment in terms of the amount and vertical distribution of leaf area and change in these variables during a growth period. This...

  17. Flavonoids intake among Polish and Spanish students.

    PubMed

    Kozłowska, Aleksandra; Przekop, Damian; Szostak-Węgierek, Dorota

    2015-01-01

    Flavonoids are a group of bioactive compounds that are extensively found in foodstuffs of plant origin. Their regular consumption plays an important role in the prevention of degenerative diseases, particularly cardiovascular disease, and cancer. The purpose of the study was to estimate dietary flavonoid intake among Polish and Spanish students and to establish the main dietary sources of flavonoids. This study included 91 Polish and 60 Spanish students. Dietary data were collected using a food frequency questionnaire. The dietary USDA Database for the flavonoid content of selected foods was used to calculate daily and weekly flavonoid intakes by the subjects. The average flavonoid consumption in the Polish students was 801 mg/day, and in Spanish students 297 mg/day. Food categories such as beverages, vegetables and fruits were found to be significant sources of flavonoids, of which tea, oranges, orange juice, dried parsley and oregano were the main contributors among Polish students and oranges, tea, chick-peas, orange juice and dried parsley were the main sources of flavonoids among Spanish students. Flavonoid consumption in Polish students was more than two times higher than in Spanish students. Compared to other population studies consumption of flavonoids in both students groups was adequate.

  18. Loss Factor of Tapered Structures for Short Bunches

    SciTech Connect

    Blednykh, A.

    2011-03-28

    Using the electromagnetic simulation code ECHO, we have found a simple phenomenological formula that accurately describes the loss factor for short bunches traversing an axisymmetric tapered collimator. In this paper, we consider tapered collimators with rectangular cross-section and use the GdfidL code to calculate the loss factor dependence on the geometric parameters for short bunches. The results for both axisymmetric and rectangular collimators are discussed. The behaviour of the impedance of tapered structures for very short bunches in the optical regime has been determined in refs. [10,11]. Here, for the loss factors for two particular geometries, we have studied the departure from the optical regime behaviour as bunch length is increased. In both cases, the ratio of the loss factor for the tapered collimator to the loss factor in the optical regime is a function only of the scaling parameter {sigma}L/d{sup 2}. The fact that the bunch length a and the taper length L appear as a product is consistent with the recent scaling derived by Stupakov in ref. [12], since there is only a weak dependence on g. One noteworthy fact that is not a priori expected is that only the larger radius or vertical half-aperture d appears. The reduction factor is independent of b. Moreover, it is striking that the specific form involving the arctan given in Eq. (5) holds for both geometries, with only the coefficient {mu} differing by a factor of {approx}2 for flat vs round. This suggests that there may be a useful phenomenological form for more general geometries which may follow from natural extensions of Eq. (5). This possibility is presently being investigated.

  19. Predictors of corticosteroid tapering in SLE patients: the Hopkins Lupus Cohort.

    PubMed

    Zahr, Z Abou; Fang, H; Magder, L S; Petri, M

    2013-06-01

    Organ damage in systemic lupus erythematosus (SLE) patients is highly associated with the use of corticosteroids. Doses of prednisone below 6 mg daily are associated with reduced organ damage. We now report on the largest prospective cohort study of predictors of prednisone tapering in SLE patients. A total of 866 SLE patients (91% female, 50% Caucasian, 43% African-American, mean age 43 years) who consented for the Hopkins Lupus Cohort from 1987 through 2009 were included. The analysis was based on patient visits in which the previously prescribed dose of prednisone was 5 mg/day. We then examined the proportion of times the patient's dose was reduced to below 5 mg/day ("tapering"). Among those patients who tapered and were followed for at least one year thereafter, we examined the proportion whose prednisone dose remained below 5 mg/day for at least one year ("Successful tapering"). Rates of tapering and successful tapering were calculated for patient subsets based on demographic and clinical characteristics. The analyses showed that Caucasians, younger patients, patients with a higher level of education, lower disease activity, or absence of urine protein were more likely to have a prednisone taper. However, successful tapering was not dependent on age, ethnicity, or education. As expected, successful tapering was more frequent in those with lower disease activity. Successful tapering was achieved more often after the year 2000. Our study suggests that successful tapering of prednisone below 5 mg has increased since the year 2000, which may reflect the greater knowledge of the long-term harm of even low-dose chronic corticosteroid use. Caucasians, younger age, higher level of education, and absence of proteinuria predicted tapering, but not successful tapering. Ongoing cutaneous or arthritis activity were associated with unsuccessful tapering. Lack of disease activity, as expected, was the only major clinical variable that significantly predicted successful

  20. [Use of the anatomical cemented femoral stem SAS I: mid-term results].

    PubMed

    Mikláš, M; Pink, M; Valoušek, T

    2015-01-01

    is an implant made to fit the proximal femur anatomy. Its highly polished surface allows for optimal fitting with the supporting bone and for even distribution of weight bearing. This results in a low rate of THA failure. In accordance with the relevant literature, the acetabular components is considered to be the weakest element in total hip replacement in terms of aseptic loosening and implant failure. At present, the SAS I stem has no Morse Eurocone taper and this is the chief obstacle hindering its more frequent use in endoprosthetics. CONCLUSIONS The results of our study are in agreement with those of other successfully implanted polished cemented femoral components. Key words: anatomical cemented femoral component, surface adjustment of the femoral stem, complications.

  1. Theoretical model of the modulation transfer function for fiber optic taper

    NASA Astrophysics Data System (ADS)

    Wang, Yaoxiang; Tian, Weijian; Bin, XiangLi

    2005-02-01

    Fiber optic taper has been used more and more widely as a relay optical component in the integrated taper assembly image intensified sensors for military and medical imaging application. In this paper, the transmission characteristic of energy in the taper is analyzed, and following the generalized definition of the modulation transfer function for sampled imaging system, a spatial averaged impulse response and a corresponding MTF component that are inherent in the sampling process of taper are deduced, and the mathematical model for evaluating the modulation transfer function of fiber optic taper is built. Finally, the dynamic and static modulation transfer function curves simulated by computer have been exhibited.

  2. Octave spanning supercontinuum in an As₂S₃ taper using ultralow pump pulse energy.

    PubMed

    Hudson, Darren D; Dekker, Stephen A; Mägi, Eric C; Judge, Alexander C; Jackson, Stuart D; Li, Enbang; Sanghera, J S; Shaw, L B; Aggarwal, I D; Eggleton, Benjamin J

    2011-04-01

    An octave spanning spectrum is generated in an As₂S₃ taper via 77 pJ pulses from an ultrafast fiber laser. Using a previously developed tapering method, we construct a 1.3 μm taper that has a zero-dispersion wavelength around 1.4 μm. The low two-photon absorption of sulfide-based chalcogenide fiber allows for higher input powers than previous efforts in selenium-based chalcogenide tapered fibers. This higher power handling capability combined with input pulse chirp compensation allows an octave spanning spectrum to be generated directly from the taper using the unamplified laser output.

  3. Carbon dioxide laser fabrication of fused-fiber couplers and tapers.

    PubMed

    Dimmick, T E; Kakarantzas, G; Birks, T A; Russell, P S

    1999-11-20

    We report the development of a fiber taper and fused-fiber coupler fabrication rig that uses a scanning, focused, CO(2) laser beam as the heat source. As a result of the pointlike heat source and the versatility associated with scanning, tapers of any transition shape and uniform taper waist can be produced. Tapers with both a linear shape and an exponential transition shape were measured. The taper waist uniformity was measured and shown to be better than +/-1.2%. The rig was also used to make fused-fiber couplers. Couplers with excess loss below -0.1 dB were routinely produced.

  4. Priorities in the Polish health care system.

    PubMed

    Nieszporska, Sylwia

    2017-01-01

    Since 1999, Polish health policy has changed, the quality of services has increased, and also the level of financing, mainly from public benefits. Despite constant growth of indexes reflecting the health status of Polish society, such as life expectancy, quality of life, or decreasing index of deaths at birth, just as in the majority of European countries, in Poland the society is growing older, which implies the necessity to reorganize the system. In this paper, the author has described the most important factors that determine the operation of the health system in Poland, as well as presents the ways it was restructured over the last few years, taking into consideration the structural, legislative, financial, organizational, and quantitative aspects. Also, the latest trends in Polish health policy, which take into account new goals of the system, have been presented within.

  5. Preliminary study of disc hydrodynamic polishing.

    PubMed

    Li, Yan; Lin, Bin; Zhang, XiaoFeng; Liu, PengFei

    2016-10-01

    In this paper, a developed polishing method based on elastic emission machining and Jules Verne-a variation on fluid jet polishing-is presented. This method is named disc hydrodynamic polishing (DHDP). A computational fluid dynamics (CFD)-based model that consists of a CFD model and an erosion model is introduced to predict the surface roughness obtained by DHDP. The performance of DHDP is studied by experiments. The slurry used in the experiments comprises 95% deionized water and 5% cerium oxide particles. Fused-silica glass is chosen as the workpiece. After the experiments, an ultrasmooth surface without cracks is obtained. The simulation results principally coincide with the experimental results. The experimental results show that the actual roughness is slightly less than the prediction and smaller particles are more favorable for obtaining a better surface roughness.

  6. [Convent nursing in Polish hospitals from 1939].

    PubMed

    Halat, M

    2000-01-01

    The author, Sister of Charity and Mother Superior of the Children's Home in Tarnów, describes the attitude of the authorities of the Polish People's Republic towards convent nursing in hospitals. The problem is exemplified by the situation of the Cracow Province of the Order of the Sisters of Charity. Apart from this main theme, Sister Mirosława Hałat says a little about the establishment of the Order and the role it played in Polish hospital care. Before presenting the fundamental problems related to the topic of the article, the author presents numerical data showing the Sisters of Charity's involvement in hospital care between World War I and World War II. This facilitates a comparison of the possibilities of providing hospital care by the Sisters of Charity at a later time. The author also describes the persecutions of the Sister of Charity by the German occupiers. Her main reflections are divided into several parts. The period from 1945 to 1949 covers the time when the Sisters of Charity tried to engage actively in the reconstruction of the ruined Polish hospital system. This involved leaving the former Polish eastern borderland and taking up duties in the so-called Regained Territories. The period from 1950 to 1989 describes the conscious, planned and ideologically directed policies of the authorities of the Polish People's Republic to nullify or at least diminish the role of the Sisters of Charity in Polish hospitals. Quoting numerous accounts and documents, the author tries to recreate the atmosphere of those times. She also writes about the Sisters of Charity's preparation for work in hospitals as well as the possibilities of their education after the war. The article presents the Sisters of Charity's activity under very difficult political conditions and is complemented by a great number of figures, graphs and source documents.

  7. De Novo Sequencing and Characterization of the Transcriptome of Dwarf Polish Wheat (Triticum polonicum L.).

    PubMed

    Wang, Yi; Wang, Chao; Wang, Xiaolu; Peng, Fan; Wang, Ruijiao; Jiang, Yulin; Zeng, Jian; Fan, Xing; Kang, Houyang; Sha, Lina; Zhang, Haiqin; Xiao, Xue; Zhou, Yonghong

    2016-01-01

    Construction as well as characterization of a polish wheat transcriptome is a crucial step to study useful traits of polish wheat. In this study, a transcriptome, including 76,014 unigenes, was assembled from dwarf polish wheat (DPW) roots, stems, and leaves using the software of Trinity. Among these unigenes, 61,748 (81.23%) unigenes were functionally annotated in public databases and classified into differentially functional types. Aligning this transcriptome against draft wheat genome released by the International Wheat Genome Sequencing Consortium (IWGSC), 57,331 (75.42%) unigenes, including 26,122 AB-specific and 2,622 D-specific unigenes, were mapped on A, B, and/or D genomes. Compared with the transcriptome of T. turgidum, 56,343 unigenes were matched with 103,327 unigenes of T. turgidum. Compared with the genomes of rice and barley, 14,404 and 7,007 unigenes were matched with 14,608 genes of barley and 7,708 genes of rice, respectively. On the other hand, 2,148, 1,611, and 2,707 unigenes were expressed specifically in roots, stems, and leaves, respectively. Finally, 5,531 SSR sequences were observed from 4,531 unigenes, and 518 primer pairs were designed.

  8. Polishing procedure and surface characterization lead tungstate crystal scintillator Road No. 723 and No. 754

    SciTech Connect

    Kellam, M

    1996-05-01

    Step by step procedures are given for polishing the scintillator rods. A Strasbaugh spindle polishing machine was used along with visual inspection and hand polishing. Extensive data is given on pre-polish surface characterization, profilometry, microphotography, and interferometry.

  9. Revision total hip arthroplasty using cemented collarless double-taper femoral components at a mean follow-up of 13 years (8 to 20): an update.

    PubMed

    Solomon, L B; Costi, K; Kosuge, D; Cordier, T; McGee, M A; Howie, D W

    2015-08-01

    The outcome of 219 revision total hip arthroplasties (THAs) in 98 male and 121 female patients, using 137 long length and 82 standard length cemented collarless double-taper femoral stems in 211 patients, with a mean age of 72 years (30 to 90) and mean follow-up of six years (two to 18) have been described previously. We have extended the follow-up to a mean of 13 years (8 to 20) in this cohort of patients in which the pre-operative bone deficiency Paprosky grading was IIIA or worse in 79% and 73% of femurs with long and standard stems, respectively. For the long stem revision group, survival to re-revision for aseptic loosening at 14 years was 97% (95% confidence interval (CI) 91 to 100) and in patients aged > 70 years, survival was 100%. Two patients (two revisions) were lost to follow-up and 86 patients with 88 revisions had died. Worst-case analysis for survival to re-revision for aseptic loosening at 14 years was 95% (95% CI 89 to 100) and 99% (95% CI 96 to 100) for patients aged > 70 years. One additional long stem was classified as loose radiographically but not revised. For the standard stem revision group, survival to re-revision for aseptic loosening at 14 years was 91% (95% CI 83 to 99). No patients were lost to follow-up and 49 patients with 51 hips had died. No additional stems were classified as loose radiographically. Femoral revision using a cemented collarless double-taper stem, particularly with a long length stem, and in patients aged > 70 years, continues to yield excellent results up to 20 years post-operatively, including in hips with considerable femoral metaphyseal bone loss. ©2015 The British Editorial Society of Bone & Joint Surgery.

  10. [Saturation of the Polish mitochondrial DNA database].

    PubMed

    Daca, Patrycja; Mielnik-Sikorska, Marta; Bednarek, Jarosław; Grzybowski, Tomasz

    2010-01-01

    The main objective of the study was a statistical evaluation of Polish mitochondrial DNA database, consisting of 1253 maternally unrelated individuals from seven different regions of Poland. Four relevant parameters were examined: haplotype diversity, nucleotide diversity, number of polymorphic positions and number of haplotypes, including HVS I and HVS II mtDNA regions. The results show that while haplotype and nucleotide diversities have already reached saturation level, the number of haplotypes and polymorphic positions rises continuously inside the database. These results indicate a need for a substantial increase in the number of haplotypes in Polish mitochondrial DNA database.

  11. Use of chemical mechanical polishing in micromachining

    DOEpatents

    Nasby, R.D.; Hetherington, D.L.; Sniegowski, J.J.; McWhorter, P.J.; Apblett, C.A.

    1998-09-08

    A process for removing topography effects during fabrication of micromachines. A sacrificial oxide layer is deposited over a level containing functional elements with etched valleys between the elements such that the sacrificial layer has sufficient thickness to fill the valleys and extend in thickness upwards to the extent that the lowest point on the upper surface of the oxide layer is at least as high as the top surface of the functional elements in the covered level. The sacrificial oxide layer is then polished down and planarized by chemical-mechanical polishing. Another layer of functional elements is then formed upon this new planarized surface. 4 figs.

  12. Use of chemical mechanical polishing in micromachining

    DOEpatents

    Nasby, Robert D.; Hetherington, Dale L.; Sniegowski, Jeffry J.; McWhorter, Paul J.; Apblett, Christopher A.

    1998-01-01

    A process for removing topography effects during fabrication of micromachines. A sacrificial oxide layer is deposited over a level containing functional elements with etched valleys between the elements such that the sacrificial layer has sufficient thickness to fill the valleys and extend in thickness upwards to the extent that the lowest point on the upper surface of the oxide layer is at least as high as the top surface of the functional elements in the covered level. The sacrificial oxide layer is then polished down and planarized by chemical-mechanical polishing. Another layer of functional elements is then formed upon this new planarized surface.

  13. Refractive index sensors based on the fused tapered special multi-mode fiber

    NASA Astrophysics Data System (ADS)

    Fu, Xing-hu; Xiu, Yan-li; Liu, Qin; Xie, Hai-yang; Yang, Chuan-qing; Zhang, Shun-yang; Fu, Guang-wei; Bi, Wei-hong

    2016-01-01

    In this paper, a novel refractive index (RI) sensor is proposed based on the fused tapered special multi-mode fiber (SMMF). Firstly, a section of SMMF is spliced between two single-mode fibers (SMFs). Then, the SMMF is processed by a fused tapering machine, and a tapered fiber structure is fabricated. Finally, a fused tapered SMMF sensor is obtained for measuring external RI. The RI sensing mechanism of tapered SMMF sensor is analyzed in detail. For different fused tapering lengths, the experimental results show that the RI sensitivity can be up to 444.517 81 nm/RIU in the RI range of 1.334 9—1.347 0. The RI sensitivity is increased with the increase of fused tapering length. Moreover, it has many advantages, including high sensitivity, compact structure, fast response and wide application range. So it can be used to measure the solution concentration in the fields of biochemistry, health care and food processing.

  14. Stem Cells

    MedlinePlus

    Stem cells are cells with the potential to develop into many different types of cells in the body. ... the body. There are two main types of stem cells: embryonic stem cells and adult stem cells. Stem ...

  15. Comparison of 3 polishing techniques for 2 all-ceramic materials.

    PubMed

    Saraç, Duygu; Turk, Tamer; Elekdag-Turk, Selma; Saraç, Y Sinaç

    2007-01-01

    The aim of this study was to compare the surface roughness produced by polishing 2 all-ceramic materials after surface conditioning. Air particle abrasion (APA) with 25-microm aluminum oxide, 9.6% hydrofluoric acid (HFA,) and APA + HFA were applied for ceramic surface conditioning. Subsequently, the ceramics were subjected to 3 polishing techniques: polishing kit, polishing paste, and polishing kit + polishing paste. Surface roughness (Ra) was evaluated profilometrically. The highest deltaRa values were obtained with the polishing kit and polishing kit + paste for the APA + HFA groups. No significant differences were observed among the polishing paste groups. Combining a polishing kit and polishing paste produced the smoothest ceramic surfaces.

  16. Rugosimetric analysis of amalgam restorations polished using different techniques.

    PubMed

    Pereira, M A; Centola, A L; do Nascimento, T N; Turbino, M L

    1998-01-01

    The objective of the present study was to submit specimens with amalgam restorations to 4 different polishing techniques and one control group without polishing. The specimens were then submitted to rugosimetric analysis and the differences compared.

  17. Modeling and simulation of wheeled polishing method for aspheric surface

    NASA Astrophysics Data System (ADS)

    Zong, Liang; Xie, Bin; Wang, Ansu

    2016-10-01

    This paper describes a new polishing tool for the polishing process of the aspheric lens: the wheeled polishing tool, equipping with an elastic polishing wheel which can automatically adapt to the surface shape of the lens, has been used to get high-precision surface based on the grinding action between the polishing wheel and the workpiece. In this paper, 3D model of polishing wheel structure is established by using the finite element analysis software. Distribution of the contact pressure between the polishing wheel and optical element is analyzed, and the contact pressure distribution function is deduced by using the least square method based on Hertz contact theory. The removal functions are deduced under different loading conditions based on Preston hypothesis. Finally, dwell time function is calculated. The simulation results show that the removal function and dwell time function are suitable for the wheeled polishing system, and thus establish a theoretical foundation for future research.

  18. The stability of dual-taper modular hip implants: a biomechanical analysis examining the effect of impact location on component stability.

    PubMed

    Frisch, Nicholas B; Lynch, Jonathan R; Banglmaier, Richard F; Silverton, Craig D

    2017-06-01

    The purpose of this study was to investigate the stability of dual-taper modular implants following impaction forces delivered at varying locations as measured by the distraction forces required to disassemble the components. Distraction of the head-neck and neck-stem (NS) tapers of dual-taper modular implants with 0°, 8°, and 15° neck angles were measured utilizing a custom-made distraction fixture attached to a servohydraulic materials test machine. Distraction was measured after hand pressing the components as well as following a simulated firm hammer blow impaction. Impacts to the 0°, 8°, 15° necks were directed axially in line with the neck, 10° anterior, and 10° proximal to the axis of the neck, respectively. Impaction increased the range of NS component distraction forces when compared to hand pressed components (1125-1743 N vs 248-302 N, respectively). Off-axis impacts resulted in significantly reduced mean (±95% confidence interval) distraction forces (8° neck, 1125 ± 117 N; 15° neck, 1212 ± 73 N), which were up to 35% lower than the mean distraction force for axial impacts to the 0° neck (1743 ± 138 N). Direction of impaction influences stability of the modular interface. The greatest stability was achieved with impaction directed in line with the longitudinal axis of the taper junction. Off-axis impaction of the 8° and 15° neck led to significantly reduced stability at the NS. Improving stability of dual-taper modular hip prostheses with appropriately directed impaction may help to minimize micromotion, component settling, fretting corrosion, and subsequent failure.

  19. Automation of Die and Mold Polishing: A Preliminary Investigation

    DTIC Science & Technology

    1990-02-02

    Seva.................54 3.2.4. Tokiwa Seiki.............65 3.3. Other Potential Machines..........69 IV. HARDWARE DESCRIPTION..............71 V...Specifications 51 Table 5 Tokiwa Seiki Polishing Machine Dimensions . 67 Table 6 Tokiwa Seiki Polishing Machine Specifications 68 Table 7 25 Factorial...Figure 11 Seva "Fixed Parts" Machine Dimensions . . 62 Figure 12 Seva Big Size Polishing Machine Dimensions 64 Figure 13 Tokiwa Seiki Polishing Machine

  20. An in vitro analysis of separation of multi-use ProTaper Universal and ProTaper Next instruments in extracted mandibular molar teeth.

    PubMed

    Ertas, Huseyin; Capar, Ismail Davut

    2015-01-01

    This study investigated the separation incidence of reused ProTaper Universal and ProTaper Next rotary instruments and identified the location of separated fragments. The root canals of extracted human mandibular molars were prepared with 10 assorted sets of ProTaper Universal and ProTaper Next instruments. After each preparation, instrument sets were autoclaved. This arrangement was repeated until an instrument fractured. The number of prepared teeth until fracture occurred was recorded for each instrument set. Teeth in which the instruments fractured were analyzed to determine the separation grade, apical relation, and coronal position. Fracture surfaces of the instruments were examined with scanning electron microscope. ProTaper Universal instruments fractured after application to a mean of 7.3 teeth, and ProTaper Next instruments after application to a mean of 5.7 teeth (p > 0.05). In the ProTaper Universal and ProTaper Next groups, F2 and X1 were the most commonly fractured instruments, respectively. Torsional and cyclic failures were evenly distributed in both the groups. The mean lengths of the fractured fragments of the instruments showed no statistically significant difference. The distance between the tip of the fractured instruments and apical constriction was similar (p > 0.05). However, the mean distance between the root canal orifice and coronal part of the fractured instrument was shorter in the ProTaper Next group (p < 0.05). The life span of ProTaper Universal and ProTaper Next instruments was the same for preparation of mandibular molar teeth. None of the instruments were fractured in the first usage.

  1. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  2. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  3. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  4. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  5. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  6. Design of multiple-ply laminated composite tapered beams

    NASA Technical Reports Server (NTRS)

    Rodriguez, P.

    1993-01-01

    A study of a special case of symmetric laminated composite cantilever beams is presented. The approach models beams that are tapered both in depth and width and investigates the effect of the ply layup angle and the ply taper on bending and interlaminar shearing stresses. For the determination of stresses and deflections, the beam stiffness matrices are expressed as linear functions of the beam length. Using classical lamination theory (CLT) the stiffness matrices are determined and assembled at strategic locations along the length of the beam. They are then inverted and necessary stiffness parameters are obtained numerically and extracted for determination of design information at each location chosen. Several ply layup configurations are investigated, and design considerations are presented based on the findings. Finally, recommendations for the design of these beams are presented, and a means for anticipating the location of highest stresses is offered.

  7. Magnetic field tunability of square tapered no-core fibers

    NASA Astrophysics Data System (ADS)

    Miao, Yinping; Wu, Jixuan; Lin, Wei; Zhang, Kailiang; Song, Binbin; Zhang, Hao; Liu, Bo

    2014-05-01

    A magnetic-field-tuned photonics device based on magnetic fluid (MF) and a square tapered no-core fiber (NCF) sandwiched between two single-mode fibers (SMFs) has been proposed. The enhanced evanescent field effect in the NCF is achieved by tapering the square NCF utilizing a fusion splicer. The spectral dependence of the proposed device on the applied magnetic-field intensity has been investigated. The results indicate that a maximal sensitivity of -18.7pm/Oe is obtained for a magnetic field strength ranging from 25Oe to 450Oe. The proposed tunable device has several advantages, including low cost, ease of fabrication, compact structure, and high sensitivity.

  8. A microsphere-taper cascading structured microfiber for temperature sensing

    NASA Astrophysics Data System (ADS)

    Xian, Pei; Feng, Guoying; Zhou, Shouhuan

    2016-04-01

    We propose and demonstrate a technique for cascading a microsphere and an abrupt taper together in a standard singlemode fiber. The proposed microsphere-taper cascading structured microfiber (MTCSM) was fabricated by fusion splicing and electric-arc discharge. Exposing the MTCSM segment to increasing temperatures results in a significant shift of the transmission notches towards longer wavelengths with a slope of approximately 17.24 pm/°C∇ from 35°C to 170°C, and the linearity is 99.8%. Due to its compact size and all-fiber configuration, the proposed sensor has advantages of good mechanical strength, simplicity and low-cost fabrication, such new device would find potential applications in communication and sensing fields.

  9. Free-electron lasers with very slow wiggler taper

    NASA Astrophysics Data System (ADS)

    Bosley, D. L.; Kevorkian, J.

    1990-09-01

    A highly accurate, explicit asymptotic solution of the electron energy and phase is found for a class of free-electron lasers with very long wavelength beams, very low electron energies, and very slow taper of the wiggler field relative to the wiggler period. Dimensionless variables are defined and normalized, and three small parameters which characterize the operation of the FEL are identified. Because of the explicit nature of the solution, our results may be directly used to calculate features such as the escape distance of the electron from the potential well and the effects of the various physical parameters. One important advantage of the very slow wiggler taper is the increased efficiency of the energy transfer from the electron beam to the signal field due to increased bucket width. Numerical calculations are performed to verify all results.

  10. Free-electron lasers with very slow wiggler taper

    NASA Astrophysics Data System (ADS)

    Bosley, D. L.; Kevorkian, J.

    1991-04-01

    A highly accurate, explicit asymptotic solution of the electron energy and phase is found for a class of free-electron lasers (FELs) with very long wavelength beams, very low electron energies, and very slow taper of the wiggler field relative to the wiggler period. Dimensionless variables are defined and normalized, and three small parameters which characterize the operation of the FEL are identified. Due to the explicit asymptotic nature of the solution, the results may be directly used to calculate features such as the escape distance of the electron from the potential well and the effects of the various physical parameters. One important advantage of the very slow wiggler taper is the increased efficiency of the energy transfer from the electron beam to the signal field due to increased bucket width. Numerical calculations are performed to verify all results.

  11. A biconical taper multi-mode fiber SERS sensor

    NASA Astrophysics Data System (ADS)

    Bai, Hua; Chen, Zhenyi; Chen, Na; Guo, Qiang; Zhang, Kun; Pang, Fufei; Wang, Tingyun

    2010-12-01

    A surface-enhanced Raman scattering (SERS) optical fiber sensor using biconical taper multi-mode fiber (MMF) is proposed. It is fabricated by fused elongating a multi-mode fiber and then coated the silver colloid on its waist. The main advantage of this sensor is that it can increase the SERS active substrate region to make more molecules be excited to produce Raman signal. Silver colloid is selected as the active substrate of SERS. A modified immobilizing process is introduced to increase the thickness of the immobilized layer and reduce the preparation time. Various concentration of R6G is used to detect the performance of the sensor. Strong Raman signal is detected from the waist of the tapered fiber. The detection sensitivity is up to 10-9M.

  12. Piezoelectric energy harvester having planform-tapered interdigitated beams

    DOEpatents

    Kellogg, Rick A [Tijeras, NM; Sumali, Hartono [Albuquerque, NM

    2011-05-24

    Embodiments of energy harvesters have a plurality of piezoelectric planform-tapered, interdigitated cantilevered beams anchored to a common frame. The plurality of beams can be arranged as two or more sets of beams with each set sharing a common sense mass affixed to their free ends. Each set thus defined being capable of motion independent of any other set of beams. Each beam can comprise a unimorph or bimorph piezoelectric configuration bonded to a conductive or non-conductive supporting layer and provided with electrical contacts to the active piezoelectric elements for collecting strain induced charge (i.e. energy). The beams are planform tapered along the entirety or a portion of their length thereby increasing the effective stress level and power output of each piezoelectric element, and are interdigitated by sets to increase the power output per unit volume of a harvester thus produced.

  13. Refractive index sensor based on tapered multicore fiber

    NASA Astrophysics Data System (ADS)

    Zhang, Chuanbiao; Ning, Tigang; Li, Jing; Pei, Li; Li, Chao; Lin, Heng

    2017-01-01

    A novel refractive index (RI) sensor based on middle-tapered multicore fiber (TMCF) is proposed and experimentally demonstrated. The sensing structure consists of two singlemode fibers (SMF) and simply spliced a section tapered four-core fiber between them. The light injected from the SMF into the multicore fiber (MCF) will excite multiple cladding mode, and interference between these modes can be affected by the surrounding refractive index (SRI), which also dictates the wavelength shift of the transmission spectrum. Our experimental investigations achieved a sensitivity around 171.2 nm/RIU for a refractive index range from 1.3448 to 1.3774. All sensors fabricated in this paper show good linearity in terms of the spectral wavelength shift versus changes in RI.

  14. A Nestable Tapered Column Concept for Large Space Structures

    NASA Technical Reports Server (NTRS)

    Bush, H. G.; Mikulas, M. M., Jr.

    1976-01-01

    A structural element concept is described which permits achievement of weight critical payloads for space shuttle. These columns are highly efficient structural members which could be the basic building elements for very large, space truss structures. Parametric results are presented which show that untapered cylindrical columns result in volume limited payloads on the space shuttle and that nestable, tapered columns easily eliminate this problem. It is recognized that the tapered column concept belongs to a class of structures which must be assembled in orbit. However, analytical results are presented which indicate that the gain in the amount of structure placed in orbit per launch, is great enough that such a concept should be considered in future systems studies of very large space structures.

  15. Design of MR brake featuring tapered inner magnetic core

    NASA Astrophysics Data System (ADS)

    Sohn, Jung Woo; Oh, Jong-Soek; Choi, Seung-Bok

    2015-04-01

    In this work, a new type of MR brake featuring tapered inner magnetic core is proposed and its braking performance is numerically evaluated. In order to achieve high braking torque with restricted size and weight of MR brake system, tapered inner magnetic core is designed and expands the area that the magnetic flux is passing by MR fluid-filled gap. The mathematical braking torque model of the proposed MR brake is derived based on the field-dependent Bingham rheological model of MR fluid. Finite element analysis is carried out to identify electromagnetic characteristics of the conventional and the proposed MR brake configuration. To demonstrate the superiority of the proposed MR brake, the braking torque of the proposed MR brake is numerically evaluated and compared with that of conventional MR brake model.

  16. X-ray beam compression by tapered waveguides

    SciTech Connect

    Chen, H.-Y. E-mail: tsaldit@gwdg.de; Hoffmann, S.; Salditt, T. E-mail: tsaldit@gwdg.de

    2015-05-11

    We have fabricated linear tapered waveguide channels filled with air and imbedded in silicon for the hard x-ray regime, using a processing scheme involving e-beam lithography, reactive ion etching, and wafer bonding. Beam compression in such channels is demonstrated by coupling a pre-focused undulator beam into the channels, and recording the exit flux and far-field diffraction patterns. We achieved a compressed beam with a spot size of 16.48 nm (horizontal) × 14.6 nm (vertical) near the waveguide exit plane, as determined from the reconstructed near-field distribution, at an exit flux which is eight times higher than that of an equivalent straight channel. Simulations indicate that this gain could reach three to four orders of magnitude for longer channels with tapering in two directions.

  17. Contact pressure distribution of chemical mechanical polishing based on bionic polishing pad

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Xing, Xue-Ling; Lu, Yu-Shan; Zhang, Liao-Yuan

    2010-12-01

    In order to improve the uniformity of the contact pressure distribution of chemical mechanical polishing, based on the Winkler foundation principle of mechanics and phyllotaxis theory of biology, a kind of stannum fixed abrasive pad with bionic surface texture has been designed, and the contact mechanism and ANSYS model have been established. By the calculating and analysis of contact pressure distribution on polishing wafer, the contact pressure distribution and the effects of the geometrical and physical parameters polishing pad on the contact pressure distributions have been obtained. The results show that the horizontal effect of the polishing pad is very small, the uniformity of contact pressure distribution can be improved, and there are the phyllotactic parameters which make the contact pressure distribution more uniformity.

  18. Outgassing Properties of Chemically Polished Titanium Materials

    NASA Astrophysics Data System (ADS)

    Kurisu, Hiroki; Kimoto, Gou; Fujii, Hiroaki; Tanaka, Kazuhiko; Yamamoto, Setsuo; Matsuura, Mitsuru; Ishizawa, Katsunobu; Nomura, Takeru; Murashige, Nobuyuki

    We developed a chemical polishing (CP) for titanium materials applicable to ultrahigh vacuum (UHV) and extremely high vacuum (XHV) systems. The surface roughness, Ra, of the chemically polished titanium is obtained to be 25 nm by the atomic force microscopy measurement. This value is smaller than those of the base metal (BM) and the buff-polished (BP) samples. The thickness of the surface oxide layer of CP sample is estimated to be 7 nm by the cross section of transmission electron micrograph. Amount of desorption gas of CP sample obtained by the thermal desorption measurement is smaller than those of BM and BP sample, and is the same as that of the mechanochemically polished (MCP) sample. The outgassing rate of CP sample after baking at 150°C×20 h is obtained to be 7×10-13 Pa•m•s-1. This value is lower than that of standard vacuum materials by two orders of magnitude after the ordinary baking.

  19. Neurocognitive Dimensions of Lexical Complexity in Polish

    ERIC Educational Resources Information Center

    Szlachta, Zanna; Bozic, Mirjana; Jelowicka, Aleksandra; Marslen-Wilson, William D.

    2012-01-01

    Neuroimaging studies of English suggest that speech comprehension engages two interdependent systems: a bilateral fronto-temporal network responsible for general perceptual and cognitive processing, and a specialised left-lateralised network supporting specifically linguistic processing. Using fMRI we test this hypothesis in Polish, a Slavic…

  20. Professional Training of Economists at Polish Universities

    ERIC Educational Resources Information Center

    Ogienko, Olena

    2016-01-01

    Polish experience in professional training of economists at university has been generalized. Structural, content and procedural peculiarities of the training have been defined. It has been proved that key factors for reforming economic education in Poland are globalization, internationalization, integration, technologization and informatization.…

  1. Knowledge Mobilisation in the Polish Education System

    ERIC Educational Resources Information Center

    Fazlagic, Jan; Erkol, Arif

    2015-01-01

    Poland has made substantial progress in improving the quality of its education system in recent years. This paper aims to describe the situation of the Polish education system from a knowledge management perspective and, to some extent, through innovation policies in education. The many challenges, this paper argues, can be tackled only through…

  2. Knowledge Mobilisation in the Polish Education System

    ERIC Educational Resources Information Center

    Fazlagic, Jan; Erkol, Arif

    2015-01-01

    Poland has made substantial progress in improving the quality of its education system in recent years. This paper aims to describe the situation of the Polish education system from a knowledge management perspective and, to some extent, through innovation policies in education. The many challenges, this paper argues, can be tackled only through…

  3. BEGINNING POLISH, VOLUME TWO. YALE LINGUISTIC SERIES.

    ERIC Educational Resources Information Center

    SCHENKER, ALEXANDER M.

    THIS BOOK OF DRILLS IS DESIGNED SPECIFICALLY FOR CLASSROOM INSTRUCTION. ITS PURPOSE IS TO SUPPLEMENT, RATHER THAN CONTINUE, VOLUME I OF "BEGINNING POLISH." IT EXPANDS THE PATTERN DRILLS GIVEN IN THE "SENTENCES" OF VOLUME I AND ADDS TO THE ILLUSTRATIONS PROVIDED IN THE "GRAMMAR." PARALLELING THE STRUCTURE OF VOLUME I, IT HAS 25 LESSONS, DIVIDED IN…

  4. Neurocognitive Dimensions of Lexical Complexity in Polish

    ERIC Educational Resources Information Center

    Szlachta, Zanna; Bozic, Mirjana; Jelowicka, Aleksandra; Marslen-Wilson, William D.

    2012-01-01

    Neuroimaging studies of English suggest that speech comprehension engages two interdependent systems: a bilateral fronto-temporal network responsible for general perceptual and cognitive processing, and a specialised left-lateralised network supporting specifically linguistic processing. Using fMRI we test this hypothesis in Polish, a Slavic…

  5. Polish Complementary Schools in Iceland and England

    ERIC Educational Resources Information Center

    Zielinska, Malgorzata; Kowzan, Piotr; Ragnarsdóttir, Hanna

    2014-01-01

    Since 2004, the opening of labour markets has spurred a considerable number of Poles to emigrate e.g. to Iceland and England. Families with school age children have had the challenge of adapting to foreign environments and school systems. Polish complementary schools have played an important, albeit ambivalent, role in this process. Through focus…

  6. Polish Youth: A Dychotomic World of Values.

    ERIC Educational Resources Information Center

    Bodnar, Artur; Zelichowski, Ryszard

    Research results show a skepticism among Polish youth concerning the possibility of implementing the accepted socialist values in political practice and denote a steady erosion of socialism's image. Youth organizations are many and varied, but it appears that most join because of the opportunity to meet friends, not because of political…

  7. Polish Complementary Schools in Iceland and England

    ERIC Educational Resources Information Center

    Zielinska, Malgorzata; Kowzan, Piotr; Ragnarsdóttir, Hanna

    2014-01-01

    Since 2004, the opening of labour markets has spurred a considerable number of Poles to emigrate e.g. to Iceland and England. Families with school age children have had the challenge of adapting to foreign environments and school systems. Polish complementary schools have played an important, albeit ambivalent, role in this process. Through focus…

  8. Professional Training of Economists at Polish Universities

    ERIC Educational Resources Information Center

    Ogienko, Olena

    2016-01-01

    Polish experience in professional training of economists at university has been generalized. Structural, content and procedural peculiarities of the training have been defined. It has been proved that key factors for reforming economic education in Poland are globalization, internationalization, integration, technologization and informatization.…

  9. Femtosecond laser polishing of optical materials

    NASA Astrophysics Data System (ADS)

    Taylor, Lauren L.; Qiao, Jun; Qiao, Jie

    2015-10-01

    Technologies including magnetorheological finishing and CNC polishing are commonly used to finish optical elements, but these methods are often expensive, generate waste through the use of fluids or abrasives, and may not be suited for specific freeform substrates due to the size and shape of finishing tools. Pulsed laser polishing has been demonstrated as a technique capable of achieving nanoscale roughness while offering waste-free fabrication, material-specific processing through direct tuning of laser radiation, and access to freeform shapes using refined beam delivery and focusing techniques. Nanosecond and microsecond pulse duration radiation has been used to perform successful melting-based polishing of a variety of different materials, but this approach leads to extensive heat accumulation resulting in subsurface damage. We have experimentally investigated the ability of femtosecond laser radiation to ablate silicon carbide and silicon. By substituting ultrafast laser radiation, polishing can be performed by direct evaporation of unwanted surface asperities with minimal heating and melting, potentially offering damage-free finishing of materials. Under unoptimized laser processing conditions, thermal effects can occur leading to material oxidation. To investigate these thermal effects, simulation of the heat accumulation mechanism in ultrafast laser ablation was performed. Simulations have been extended to investigate the optimum scanning speed and pulse energy required for processing various substrates. Modeling methodologies and simulation results will be presented.

  10. Freeform grinding and polishing with PROSurf

    NASA Astrophysics Data System (ADS)

    Wolfs, Franciscus; Fess, Edward; DeFisher, Scott; Torres, Josh; Ross, James

    2015-10-01

    Recently, the desire to use freeform optics has been increasing, including shapes such as torics and anamorphic aspheres. Freeform optics can be used to expand capabilities of optical systems. They can compensate for limitations in rotationally symmetric optics. These same traits that give freeform optics the ability to improve optical systems also makes them more challenging to manufacture. This holds true for grinding, polishing, and metrology. As freeform optics become more prevalent in the industry, tolerances will become more stringent, requiring deterministic manufacturing processes. To generate freeforms, it is crucial to have control over all aspects of the process. Controlling the surface definition is important for achieving a better surface finish during processing. Metrology will be required to adjust tool paths at various stages in manufacturing. During grinding, metrology will be used to adjust tool positions relative to the nominal tool path to compensate for repeatable machine and tooling error. For polishing, metrology will be used to deterministically adjust dwell relative to the amount of the error in different surface locations, allowing for convergence towards the desired surface at a uniform rate. OptiPro has developed PROSurf, a CAM software package for creating freeform tool paths and applying metrology-based corrections. The software can be used for both grinding and polishing freeform optics. The software has flexibility to allow for different methods of modelling the surface: mathematical equations, solid models, and point clouds. The software is designed to make it easier to manufacture and polish complex freeform optics.

  11. Sexual Health of Polish Athletes with Disabilities

    PubMed Central

    Plinta, Ryszard; Sobiecka, Joanna; Drosdzol-Cop, Agnieszka; Nowak-Brzezińska, Agnieszka; Kobiołka, Agnieszka; Skrzypulec-Plinta, Violetta

    2015-01-01

    The purpose of this study was to determine sexual functioning of Polish athletes with disabilities (including paralympians). The study encompassed 218 people with physical disabilities, aged between 18 and 45 (149 men and 69 women). The entire research population was divided into three groups: Polish paralympians (n = 45), athletes with disabilities (n = 126) and non-athletes with disabilities (n = 47). The quality of sexual life of Polish paralympians was measured by using the Polish version of Female Sexual Function Index and International Index of Erectile Function. Clinically significant erectile dysfunctions were most often diagnosed in non-athletes (83.33%) with 50% result of severe erectile dysfunctions, followed by athletes and paralympians with comparable results of 56.98% and 54.17% respectively (p = 0.00388). Statistically significant clinical sexual dysfunctions concerned lubrication, orgasm as well as pain domains, and prevailed among female non-athletes (68.42%, 68.42% and 57.89%). Practising sports at the highest level has a favourable effect on the sexuality of men and women with physical disabilities. Men with physical disabilities manifest more sexual disorders than women, an aspect which should be considered by health-care professionals working with people with disabilities. PMID:26133132

  12. Analysis of Polish Vowels of Tracheoesophageal Speakers.

    PubMed

    Mięsikowska, Marzena

    2017-03-01

    The aim of this study was to determine the acoustical differences between normal and tracheoesophageal Polish speakers during Polish vowel production. Formant frequencies, namely, the first (F1) and second (F2) formant frequencies for 6 Polish vowels produced by 11 normal and 11 tracheoesophageal speakers, were analyzed using statistical analysis of variance and discriminant analysis. Spectral analysis showed that the F1 and F2 values of Polish vowels produced by tracheoesophageal speakers were significantly higher than those produced by normal speakers, with the exception of the F2 value of /i/ produced by tracheoesophageal speakers. Analysis of variance showed significant differences between speeches based on the F1 and F2 formant frequencies. Discriminant analysis based on the formant frequencies for F1 and F2 exhibited 73.33% of the mean classification score for tracheoesophageal speakers and 96.36% for normal speakers. Tracheoesophageal speakers exhibit higher F1 and F2 formant frequencies, with the exception of the F2 value for the vowel /i/ than normal speakers. Discriminant analysis showed that the classification process for TE speech exhibits lower accuracy due to the poorer classification of the vowels /i/, /u/, and /y/. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  13. Development of high-power gyrotrons with gradually tapered cavity

    SciTech Connect

    Lei Chaojun; Yu Sheng; Niu Xinjian; Liu Yinghui; Li Hongfu; Li Xiang

    2012-12-15

    In high power gyrotrons, the parasitic modes coupled with the operating mode cannot be avoided in the beam-wave interaction. These parasitic modes will decrease the efficiency of the gyrotrons. The purity of the operating mode affected by different tapers should be carefully studied. The steady-state self-consistent nonlinear theory for gyrotron with gradually tapered cavity is developed in this paper. A steady-state calculation code including 'cold cavity' and 'hot cavity' is designed. By comparison, a time-domain model analysis of gyrotron operation is also studied by particle-in-cell (PIC). It is found that the tapers of gyrotron have different influences on the modes coupling between the operating mode and the parasitic modes. During the study, an example of 94 GHz gyrotron with pure operating mode TE{sub 03} has been designed. The purity of the operating mode in the optimized cavity is up to -77 dB, and in output waveguide of the cavity is up to -76 dB. At the same time, the beam-wave interaction in the designed cavity has been simulated, too. An output power of 120 kW, corresponding to 41.6% efficiency and an oscillation frequency of 94.099 GHz have been achieved with a 50 kV, 6 A helical electron beam at a guiding magnetic field of 3.5485 T. The results show that the power in spurious modes of the optimized cavity may be kept far below than that of the traditional tapered cavity.

  14. Coherent beam combining architectures for high power tapered laser arrays

    NASA Astrophysics Data System (ADS)

    Schimmel, G.; Janicot, S.; Hanna, M.; Decker, J.; Crump, P.; Erbert, G.; Witte, U.; Traub, M.; Georges, P.; Lucas-Leclin, G.

    2017-02-01

    Coherent beam combining (CBC) aims at increasing the spatial brightness of lasers. It consists in maintaining a constant phase relationship between different emitters, in order to combine them constructively in one single beam. We have investigated the CBC of an array of five individually-addressable high-power tapered laser diodes at λ = 976 nm, in two architectures: the first one utilizes the self-organization of the lasers in an interferometric extended-cavity, which ensures their mutual coherence; the second one relies on the injection of the emitters by a single-frequency laser diode. In both cases, the coherent combining of the phase-locked beams is ensured on the front side of the array by a transmission diffractive grating with 98% efficiency. The passive phase-locking of the laser bar is obtained up to 5 A (per emitter). An optimization algorithm is implemented to find the proper currents in the five ridge sections that ensured the maximum combined power on the front side. Under these conditions we achieve a maximum combined power of 7.5 W. In the active MOPA configuration, we can increase the currents in the tapered sections up to 6 A and get a combined power of 11.5 W, corresponding to a combining efficiency of 76%. It is limited by the beam quality of the tapered emitters and by fast phase fluctuations between emitters. Still, these results confirm the potential of CBC approaches with tapered lasers to provide a high-power and high-brightness beam, and compare with the current state-of-the-art with laser diodes.

  15. Gas insulated transmission line having tapered particle trapping ring

    DOEpatents

    Cookson, Alan H.

    1982-01-01

    A gas-insulated transmission line includes an outer sheath, an inner conductor, insulating supports and an insulating gas. A particle-trapping ring is secured to each insulating support, and it is comprised of a central portion and two tapered end portions. The ends of the particle trapping ring have a smaller diameter than the central portion of the ring, so as to enable the use of the particle trapping ring in a curved transmission line.

  16. The taper disaster--how could it happen?

    PubMed

    Morlock, Michael M

    2015-01-01

    Corrosion of metallic implants in contact with body fluids is unavoidable, especially at interfaces where movement occurs or in gaps. Corrosion became clinically relevant with the introduction of large modular metal-on-metal total hip joint articulations (MoM THA) early in the 21st century. This review attempts to summarise the scientific knowledge about taper problems available at the time of introduction of these bearings, why this "disaster" could happen. It is speculated that changes to the taper connection made in the 1990s to increase the range of motion with small heads (28 and 32 mm) reduced the mechanical strength of this connection, which did not matter for small heads. With the use of large and very large metal heads in MoM articulations, which have a larger lever arm and can generate high friction in unfavourable situations, suddenly the taper interface exhibited corrosion problems on a previously unknown scale. It is speculated that due to the higher mechanical loading with larger heads, the taper connection became less forgiving with respect to assembly conditions, contamination, manufacturing tolerances and other factors, which are yet not known. Since no major clinical problems had been reported before the introduction of these bearings and the pre-clinical testing was very successful, the disaster took its course. The patient-implant-surgeon system is a very complex intrinsically hazardous system. Pre-clinical testing addresses few and defined factors and such, good results cannot be directly transferred to the clinical reality. A controlled stepwise introduction of innovations is required.

  17. Plasmonic Sensors Based on Doubly-Deposited Tapered Optical Fibers

    PubMed Central

    González-Cano, Agustín; Navarrete, María-Cruz; Esteban, Óscar; Díaz-Herrera, Natalia

    2014-01-01

    A review of the surface plasmon resonance (SPR) transducers based on tapered fibers that have been developed in the last years is presented. The devices have proved their good performance (specifically, in terms of sensitivity) and their versatility and they are a very good option to be considered as basis for any kind of chemical and biological sensor. The technology has now reached its maturity and here we summarize some of the characteristics of the devices produced. PMID:24618726

  18. Plasmonic sensors based on doubly-deposited tapered optical fibers.

    PubMed

    González-Cano, Agustín; Navarrete, María-Cruz; Esteban, Óscar; Díaz-Herrera, Natalia

    2014-03-10

    A review of the surface plasmon resonance (SPR) transducers based on tapered fibers that have been developed in the last years is presented. The devices have proved their good performance (specifically, in terms of sensitivity) and their versatility and they are a very good option to be considered as basis for any kind of chemical and biological sensor. The technology has now reached its maturity and here we summarize some of the characteristics of the devices produced.

  19. [The life of Polish students at the Polish School of Medicine at the University of Edinburgh].

    PubMed

    Gebertt, S

    1994-01-01

    The article has been written by a former student of the Polish School of Medicine at the University of Edinburgh, a member of the Polish Forces in Britain. The reminiscences concentrate on day to day life of others, like himself, seconded from the Forces to continue their medical studies. Statistical data concerning the activities of Polish School of Medicine are presented and analysed. Detailed mention is made of various routes by which Polish students reached Great Britain from the time of defeat and partition of Poland between Germany and Soviet Union. The various phases of relationship and attitudes between Polish Armed Forces and the body of students are described and illustrated by extracts from personal memoirs. The number of other topics is presented and discussed: The difficulties and problems encountered in living and studying amongst people, who although sympathetic, but whose language, culture and customs were completely foreign to the Poles. The ways in which individuals and groups of students tried and in many instances managed to overcome these obstacles, forging links with their Scottish colleagues and population at large. The participation in various joint activities like Settlement Day, work in agricultural camps, sports, Scottish students Unions and Representative Councils etc. are described. "Inner life" of Polish students concentrated in "Bursa" (an equivalent of University Residence) is presented in a light-hearted way. Large detachments of a foreign army, living, amongst albeit friendly population, are bound to cause, sometimes serious, friction. Very much in relation to this problem the role of Polish students as ambassadors of Poland and Polish Causes are presented and their value assessed.

  20. A woman's experience of tapering from buprenorphine during pregnancy.

    PubMed

    Welle-Strand, Gabrielle Katrine; Kvamme, Odd; Andreassen, Andreas; Ravndal, Edle

    2014-12-24

    Although opioid maintenance treatment (OMT) is the treatment of choice for pregnant opioid-dependent patients, some professionals argue that tapering the medication dose will reduce the severity of neonatal abstinence syndrome (NAS). This case description is based on the patient's detailed blog, and medical records from her general practitioner and the hospital. The patient is an employed, 32-year-old drug-abstinent woman in OMT. Her taper from 24 mg of buprenorphine started at 14 weeks' gestation and is slow, with withdrawal symptoms increasing gradually. In pregnancy week 31, she is off buprenorphine but she has severe withdrawal symptoms. She chose to go back on 4 mg of buprenorphine. The patient's son was born in pregnancy week 38+3, weighs 2950 g and does not require pharmacological treatment for NAS. The fetus most probably did experience fetal stress during the patient's tapering. It was the right decision by the patient to go back on buprenorphine. 2014 BMJ Publishing Group Ltd.

  1. Schottky photodetector with tapered thin metal strip on silicon waveguide

    NASA Astrophysics Data System (ADS)

    Guo, Jingshu; Wu, Zhiwei; Li, Yuan; Zhao, Yanli

    2016-01-01

    We propose a Schottky photodetector with tapered thin metal strip on SOI platform. Schottky photodetector can detect photons below the semiconductor bandgap energy by exploiting the internal photoemission. In the internal photoemission process, the hot carriers generate in the tapered thin metal strip where light absorption occurs, and part of these carriers can be emitted over the Schottky barrier and collected as photocurrent. The small thickness of the tapered metal strip contributes to a high internal quantum efficiency of 11.25%. This metal-semiconductor structure acts as a photonics-plasmonics mode convertor. According to 3D-FDTD simulation, about 95.8% of the incident optical power can be absorbed in the absorption area within 4.5μm at wavelength of 1550 nm. The responsivity is estimated to be 0.135A/W at 1550 nm. This compact design with a low dark current has a minimum detectable power of -23.15 dβm. We argue that this design can promote the progress of all-Si photo-detection in near-infrared communication band.

  2. A woman's experience of tapering from buprenorphine during pregnancy

    PubMed Central

    Welle-Strand, Gabrielle Katrine; Kvamme, Odd; Andreassen, Andreas; Ravndal, Edle

    2014-01-01

    Although opioid maintenance treatment (OMT) is the treatment of choice for pregnant opioid-dependent patients, some professionals argue that tapering the medication dose will reduce the severity of neonatal abstinence syndrome (NAS). This case description is based on the patient's detailed blog, and medical records from her general practitioner and the hospital. The patient is an employed, 32-year-old drug-abstinent woman in OMT. Her taper from 24 mg of buprenorphine started at 14 weeks’ gestation and is slow, with withdrawal symptoms increasing gradually. In pregnancy week 31, she is off buprenorphine but she has severe withdrawal symptoms. She chose to go back on 4 mg of buprenorphine. The patient's son was born in pregnancy week 38+3, weighs 2950 g and does not require pharmacological treatment for NAS. The fetus most probably did experience fetal stress during the patient's tapering. It was the right decision by the patient to go back on buprenorphine. PMID:25540212

  3. Reconfigurable tapered coaxial slot antenna for hepatic microwave ablation.

    PubMed

    Malhotra, Neeru; Marwaha, Anupma; Kumar, Ajay

    2016-01-01

    Microwave ablation is rapidly being rediscovered and developed for treating many cancers of liver, lung, kidney and bone, as well as arrhythmias and other medical conditions. The microwaves ablate tissue by heating it to cytotoxic temperatures. The microwave antenna design suffers the challenges of effective coupling and penetration into body tissues, uncontrolled power deposition due to applicator construction limitations affecting uniform heating of target region, and narrowband operation leading to mismatch for many patients and detrimental heating. To meet out the requirements of wideband operation and localized lesion reconfigurable linearly tapered slot interstitial wideband antenna has been proposed for working in the 1.38 GHz to 4.31 GHz frequency band. The performance of the antenna is evaluated by using FEM-based HFSS software. The slot height and taper height are reconfigured for parametric analysis achieving maximum impedance matching and spherical ablation zone without requiring any additional adjustable structures. The tapering of the slot in coaxial antenna generates current distribution at the edges of the slot for maximizing specific absorption rate.

  4. Magnetic field tunability of optical microfiber taper integrated with ferrofluid.

    PubMed

    Miao, Yinping; Wu, Jixuan; Lin, Wei; Zhang, Kailiang; Yuan, Yujie; Song, Binbin; Zhang, Hao; Liu, Bo; Yao, Jianquan

    2013-12-02

    Optical microfiber taper has unique propagation properties, which provides versatile waveguide structure to design the tunable photonic devices. In this paper, the S-tapered microfiber is fabricated by using simple fusion spicing. The spectral characteristics of microfiber taper integrated with ferrofluid under different magnetic-field intensities have been theoretically analyzed and experimentally demonstrated. The spectrum are both found to become highly magnetic-field-dependent. The results indicate the transmission and wavelength of the dips are adjustable by changing magnetic field intensity. The response of this device to the magnetic field intensity exhibits a Langvin function. Moreover, there is a linear relationship between the transmission loss and magnetic field intensity for a magnetic field intensity range of 25 to 200Oe, and the sensitivities as high as 0.13056dB/Oe and 0.056nm/Oe have been achieved, respectively. This suggests a potential application of this device as a tunable all-in-fiber photonic device, such as magneto-optic modulator, filter, and sensing element.

  5. Portable fiber-optic taper coupled optical microscopy platform

    NASA Astrophysics Data System (ADS)

    Wang, Weiming; Yu, Yan; Huang, Hui; Ou, Jinping

    2017-04-01

    The optical fiber taper coupled with CMOS has advantages of high sensitivity, compact structure and low distortion in the imaging platform. So it is widely used in low light, high speed and X-ray imaging systems. In the meanwhile, the peculiarity of the coupled structure can meet the needs of the demand in microscopy imaging. Toward this end, we developed a microscopic imaging platform based on the coupling of cellphone camera module and fiber optic taper for the measurement of the human blood samples and ascaris lumbricoides. The platform, weighing 70 grams, is based on the existing camera module of the smartphone and a fiber-optic array which providing a magnification factor of 6x.The top facet of the taper, on which samples are placed, serves as an irregular sampling grid for contact imaging. The magnified images of the sample, located on the bottom facet of the fiber, are then projected onto the CMOS sensor. This paper introduces the portable medical imaging system based on the optical fiber coupling with CMOS, and theoretically analyzes the feasibility of the system. The image data and process results either can be stored on the memory or transmitted to the remote medical institutions for the telemedicine. We validate the performance of this cell-phone based microscopy platform using human blood samples and test target, achieving comparable results to a standard bench-top microscope.

  6. Single-mode fiber linearly tapered planar waveguide tunable coupler

    NASA Astrophysics Data System (ADS)

    Das, Alok K.; Hussain, Anwar

    1997-09-01

    We developed a simple system of tunable fiber film coupler using a linearly tapered thin-film planar waveguide (PWG) evanescently coupled by a single-mode distributed fiber half-coupler. We investigate the characteristics of the coupler theoretically and experimentally taking into consideration the refractive index ( n f ) of nonuniform films, the magnitude of nonuniformity ( m ) of the films, and the source wavelength ( ). The thickness variation of the nonuniform film is along the direction of propagation of optical power. Tapered and plano concave thin films of a mix of oils as well as a plano concave poly(methyl methacrylate) film were fabricated to serve as nonuniform PWG s. Similar to single-mode fiber with a uniform thickness PWG coupler, such a coupler also provides light modulation with a change of n f . However, position shifting of a half-coupler in a tapered PWG structure along the direction of propagation exhibits the variation of fiber throughput power. This action serves as a simple system for a tunable fiber film coupler. Wavelength-dependent throughput fiber power for such a coupler also behaves as a filter. The center wavelength can be controlled by shifting the position of the half-coupler. A coupling fiber as a half-coupler can be used for efficient coupling. We performed a theoretical analysis of the structure using Marcuse s model and observed good agreement with the experimental results.

  7. Model-based optimization of tapered free-electron lasers

    NASA Astrophysics Data System (ADS)

    Mak, Alan; Curbis, Francesca; Werin, Sverker

    2015-04-01

    The energy extraction efficiency is a figure of merit for a free-electron laser (FEL). It can be enhanced by the technique of undulator tapering, which enables the sustained growth of radiation power beyond the initial saturation point. In the development of a single-pass x-ray FEL, it is important to exploit the full potential of this technique and optimize the taper profile aw(z ). Our approach to the optimization is based on the theoretical model by Kroll, Morton, and Rosenbluth, whereby the taper profile aw(z ) is not a predetermined function (such as linear or exponential) but is determined by the physics of a resonant particle. For further enhancement of the energy extraction efficiency, we propose a modification to the model, which involves manipulations of the resonant particle's phase. Using the numerical simulation code GENESIS, we apply our model-based optimization methods to a case of the future FEL at the MAX IV Laboratory (Lund, Sweden), as well as a case of the LCLS-II facility (Stanford, USA).

  8. Comparative evaluation of apically extruded debris with V-Taper, ProTaper Next, and the Self-adjusting File systems

    PubMed Central

    Vyavahare, Nishant K.; Raghavendra, Srinidhi Surya; Desai, Niranjan N.

    2016-01-01

    Background: Complete cleaning of the root canal is the goal for ensuring success in endodontics. Removal of debris plays an important role in achieving this goal. In spite of advancements in instrument design, apical extrusion of debris remains a source of inflammation in the periradicular region. Aim: To comparatively evaluate the amount of apically extruded debris with V-Taper, ProTaper Next, and the self-adjusting File (SAF) system. Materials and Methods: Sixty-four extracted human mandibular teeth with straight root canals were taken. Access openings were done and working length determined. The samples were randomly divided into three groups: Group I - V-Taper files (n = 20), Group II - ProTaper Next (n = 20), Group III - SAF (n = 20). Biomechanical preparation was completed and the debris collected in vials to be quantitatively determined. The data obtained was statistically analyzed using ANOVA and post hoc Tukey's test. Results: All the specimens showed apical debris extrusion. SAF showed significantly less debris extrusion compared to V-Taper and ProTaper Next (P < 0.001). Among Groups I and II, ProTaper Next showed lesser debris extrusion as compared to V-Taper, but it was not significant (P = 0.124). Conclusion: The SAF showed least amount of apical debris extrusion when compared to newer rotary endodontic instruments. This indicates that the incidence of inter-treatment flare-ups due to debris extrusion would be less with the SAF. PMID:27217636

  9. A Tree Taper Model Based on Similar Triangles and Use of Crown Ratio as a Measure of Form in Taper Equations for Longleaf Pine

    Treesearch

    Dennis J. Shaw; Ralph S. Meldahl; John S. Kush; Greg L. Somers

    2003-01-01

    We used data from 322 natural longleaf pine (Pinus palustris Mill.) trees to include crown ratio as a continuous variable in taper equations. The data were divided into 10 crown-ratio classes and fitted taper equations into each class to detect trends in the coefficients. For application to longleaf pine, we replaced coefficients that exhibited a...

  10. Design Considerations of Polishing Lap for Computer-Controlled Cylindrical Polishing Process

    NASA Technical Reports Server (NTRS)

    Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    The future X-ray observatory missions, such as International X-ray Observatory, require grazing incidence replicated optics of extremely large collecting area (3 m2) in combination with angular resolution of less than 5 arcsec half-power diameter. The resolution of a mirror shell depends ultimately on the quality of the cylindrical mandrels from which they are being replicated. Mid-spatial-frequency axial figure error is a dominant contributor in the error budget of the mandrel. This paper presents our efforts to develop a deterministic cylindrical polishing process in order to keep the mid-spatial-frequency axial figure errors to a minimum. Simulation studies have been performed to optimize the operational parameters as well as the polishing lap configuration. Furthermore, depending upon the surface error profile, a model for localized polishing based on dwell time approach is developed. Using the inputs from the mathematical model, a mandrel, having conical approximated Wolter-1 geometry, has been polished on a newly developed computer-controlled cylindrical polishing machine. We report our first experimental results and discuss plans for further improvements in the polishing process.

  11. Between Polish Positivism and American Capitalism: The Educational Agents' Experiment in the Polish-American Community, 1889-1914

    ERIC Educational Resources Information Center

    Jaroszynska-Kirchmann, Anna D.

    2008-01-01

    "Ameryka-Echo" was one of the most popular Polish-language weeklies, published in the United States between 1889 and 1972. Its founder and owner, Antoni A. Paryski, consciously sought to transplant ideas of Polish Positivism to the Polish-American immigrant communities in the United States. Reading was a central concept of…

  12. Between Polish Positivism and American Capitalism: The Educational Agents' Experiment in the Polish-American Community, 1889-1914

    ERIC Educational Resources Information Center

    Jaroszynska-Kirchmann, Anna D.

    2008-01-01

    "Ameryka-Echo" was one of the most popular Polish-language weeklies, published in the United States between 1889 and 1972. Its founder and owner, Antoni A. Paryski, consciously sought to transplant ideas of Polish Positivism to the Polish-American immigrant communities in the United States. Reading was a central concept of…

  13. Evaluation of the polished surface characteristic of cobalt-chrome castings subsequent to various finishing and polishing techniques.

    PubMed

    Ponnanna, A A; Joshi, S M; Bhat, S; Shetty, P

    2001-01-01

    Finishing and Polishing constitutes an essential requisite after the fabrication of removable partial dentures. Improper finishing and polishing of cast framework will adversely affect the quality of functional units of partial dentures due to reduced dimensions. In this study the polished surface characteristic and loss of weight of the casting were evaluated and compared following different finishing and polishing techniques. A total number of thirty test specimens were cast and each surface finishing and polishing technique was carried out with a high speed polishing motor and an electropolishing unit under standardised conditions. Surface roughness was evaluated by means of a surface roughness analyzing instrument, Perthometer. The loss of weight due to the metal lost was observed on a sensitive electronic balance. The results of polishing technique employed with G3 group revealed better surface characteristic. It may be understood that sandblasting causes initial roughness and the sequence of coarse cylindrical abrasive, Black hard rubber polisher (coarse grit-Dentauram), Grey hard rubber polisher (Med-grit-Dentauram), Green hard rubber polisher (Fine-grit-Dentauram), Grey flexible rubber polisher (Fine grit-Renfert), felt buff with pumice slurry and felt buff with green polishing compound (Degussa) produced improved surface in this case. The loss of weight due to metal lost show concern with technique groups G4, G5, G6. It can be avoided by judicious sandblasting and application of proper grit of abrasive agents.

  14. Hematological responses to training and taper in competitive swimmers: relationships with performance.

    PubMed

    Mujika, I; Padilla, S; Geyssant, A; Chatard, J C

    1998-08-01

    The purpose of this study was to monitor hematological changes during 12 weeks of intense training and 4 weeks of taper in 8 highly trained competitive swimmers, and to assess the relationships between hematological variables and competition performance. Venous blood samples were obtained in the mid-season (wk 10), before taper (wk 22) and after taper (wk 26). Swimmers participated in actual competitions within 1 wk of each blood testing. Comparisons were made between swimmers improving performance with taper by more than 2% (n = 4), efficient (GE) or less than 2% (n = 4), less efficient (GLE). Hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) increased significantly during training. MCH and MCHC decreased during taper, while serum iron tended to increase (P = 0.07). Improvement in performance during taper was positively correlated with post-taper red cell count (RCC): r = 0.83, P < 0.05. GE swimmers had higher pre- and post-taper RCC, and post-taper Hb and hematocrit. In conclusion, intense training and taper appeared to influence the hematological status and performance capacity of the studied group of swimmers.

  15. Where science meets practice: Olympic coaches' crafting of the tapering process.

    PubMed

    Ritchie, Darren; Allen, Justine B; Kirkland, Andrew

    2017-08-07

    Although there is research providing physiologically-based guidance for the content of the taper, this study was the first to examine how coaches actually implement the taper. The purpose of this study was to examine the taper planning and implementation processes of successful Olympic coaches leading up to major competitions and how they learned about tapering. Seven track and field coaches participated in semi-structured interviews exploring their tapering processes. To be considered for inclusion, coaches were required to have coached one or more athletes to an Olympic or Paralympic medal. Through a process of axial and open coding interview transcripts were analysed and lower and higher order themes developed describing the coaches' tapering processes. Our findings indicate that the strategies employed to achieve the desired physiological adaptions of the taper were consistent with research (e.g., reduction in volume whilst maintaining intensity and frequency). However, our findings also suggest that tapering is far from a straight forward "textbook" process. The taper was not restricted to physiological outcomes with coaches considering athletes' psychological as well as physical state. Coaches also involved the athlete in the process, adapted the taper to the athlete, continually monitored its progress, and adapted it further as required.

  16. In-situ Tapering of Chalcogenide Fiber for Mid-infrared Supercontinuum Generation

    PubMed Central

    Rudy, Charles W.; Marandi, Alireza; Vodopyanov, Konstantin L.; Byer, Robert L.

    2013-01-01

    Supercontinuum generation (SCG) in a tapered chalcogenide fiber is desirable for broadening mid-infrared (or mid-IR, roughly the 2-20 μm wavelength range) frequency combs1, 2 for applications such as molecular fingerprinting, 3 trace gas detection, 4 laser-driven particle acceleration, 5 and x-ray production via high harmonic generation. 6 Achieving efficient SCG in a tapered optical fiber requires precise control of the group velocity dispersion (GVD) and the temporal properties of the optical pulses at the beginning of the fiber, 7 which depend strongly on the geometry of the taper. 8 Due to variations in the tapering setup and procedure for successive SCG experiments-such as fiber length, tapering environment temperature, or power coupled into the fiber, in-situ spectral monitoring of the SCG is necessary to optimize the output spectrum for a single experiment. In-situ fiber tapering for SCG consists of coupling the pump source through the fiber to be tapered to a spectral measurement device. The fiber is then tapered while the spectral measurement signal is observed in real-time. When the signal reaches its peak, the tapering is stopped. The in-situ tapering procedure allows for generation of a stable, octave-spanning, mid-IR frequency comb from the sub harmonic of a commercially available near-IR frequency comb. 9 This method lowers cost due to the reduction in time and materials required to fabricate an optimal taper with a waist length of only 2 mm. The in-situ tapering technique can be extended to optimizing microstructured optical fiber (MOF) for SCG10 or tuning of the passband of MOFs, 11 optimizing tapered fiber pairs for fused fiber couplers12 and wavelength division multiplexers (WDMs), 13 or modifying dispersion compensation for compression or stretching of optical pulses.14-16 PMID:23748947

  17. Chemical mechanical polishing of boron-doped polycrystalline silicon

    NASA Astrophysics Data System (ADS)

    Pirayesh, Hamidreza; Cadien, Kenneth

    2014-03-01

    Chemical mechanical polishing (CMP) is a technique which helps to print a smaller depth of focus and smoother surface in micro fabrication industry. In this project, boron doped polysilicon is used as a fill material for Through Silicon Vias (TSV) creating a 3D package. It is shown that the presence of boron as dopant suppresses the polysilicon polish rate. To increase the polish rate, understanding the mechanism of polish rate retardation is essential. We believe that the electrical effects play the major role in this phenomenon and by reducing this effect we are able to increase the polish rate.

  18. Silica based polishing of {100} and {111} single crystal diamond

    PubMed Central

    Thomas, Evan L H; Mandal, Soumen; Brousseau, Emmanuel B; Williams, Oliver A

    2014-01-01

    Diamond is one of the hardest and most difficult to polish materials. In this paper, the polishing of {111} and {100} single crystal diamond surfaces by standard chemical mechanical polishing, as used in the silicon industry, is demonstrated. A Logitech Tribo Chemical Mechanical Polishing system with Logitech SF1 Syton and a polyurethane/polyester polishing pad was used. A reduction in roughness from 0.92 to 0.23 nm root mean square and 0.31 to 0.09 nm rms for {100} and {111} samples respectively was observed. PMID:27877689

  19. Polishing Material Removal Correlation on PMMA - FEM Simulation

    NASA Astrophysics Data System (ADS)

    Almeida, R.; Börret, R.; Rimkus, W.; Harrison, D. K.; DeSilva, A. K. M.

    2016-02-01

    The complexity of polishing is very high and experience in this field is required to achieve reproducible deterministic results concerning shape accuracy. The goal of this work is to predict the material removal of the polishing process on PMMA (Polymethylmethacrylate) using an industrial robot polisher. In order to predict the material removal, a FEM Model was created representing the polishing process. This model will help to predict the material removal when polishing parameters are changed. Experiments were carried out and compared to the results obtained from the different parameters tested in the simulation.

  20. Tooth polishing: Relevance in present day periodontal practice

    PubMed Central

    Madan, Charu; Bains, Rhythm; Bains, Vivek K.

    2009-01-01

    Time has seen the emergence of more efficient and effective devices like jet abrasives. However, the role of rubber cups with prophy angles cannot be overlooked as they are still being widely used and provide an economical alternative. Owing to several shortcomings associated with the air polishing device using sodium bicarbonate (NaHCO3), trends are shifting towards the usage of low abrasive powders. Recent demonstration of Glycine Powder Air Polishing (GPAP) in removing subgingival biofilm results in less gingival erosion than hand instrumentation or NaHCO3 air-polishing. Despite the emergence of latest advances in polishing, data suggesting selective polishing of teeth is compelling. PMID:20376245

  1. Analysis of Surface Characteristics of ProTaper Universal and ProTaper Next Instruments by Scanning Electron Microscopy

    PubMed Central

    Bennett, Jeffery; Chung, Kwok-Hung; Fong, Hanson; Johnson, James

    2017-01-01

    Background Many new rotary files systems have been introduced, however, limited research has been conducted related to the surface irregularities of these files and if these have any effects on the files themselves. Hence, the aim of the present study was to analyze surface irregularities of the ProTaper® Universal rotary files (PTU) and the ProTaper Next™ rotary files (PTN) before and after instrumentation in curved canals. The main objective was to investigate the nature of these irregularities and how they might influence the use and fracture of rotary files during root-canal treatments. Material and Methods The files were examined pre-operatively using a stereomicroscope and scanning electron microscopy(SEM) to analyze surface imperfections and the presence of particles. Mesial roots of forty extracted mandibular molars were selected. Each instrument was used to prepare one of the mesial canals. The files were then rinsed with alcohol, and autoclaved and analyzed again. Results Of the 80 files used in this study, five files fractured, five files unwound and seven files were curved or bent and they all belonged to the PTU group. Irregularities and debris could be visualized with the SEM on both unused PTU and PTN files. Most of the debris was found associated with deeper milling grooves and defects on the surface of the metal. Surface analysis of the files that were used and sterilized were performed and the SEM images demonstrated organic debris, metal flash, and crack formation and initiation of fractures for both file types. All files showed machining grooves, metal flash, debris, and defects on cutting edges. Conclusions These irregularities appear to be critical in the accumulation of debris and initiation of fatigue and crack propagation within the NiTi alloy. The accumulation of debris could be a concern due to the potential exchange of organic debris between patients. Key words:ProTaper® Universal, ProTaper Next™, surface characteristics, SEM. PMID

  2. Analysis of Surface Characteristics of ProTaper Universal and ProTaper Next Instruments by Scanning Electron Microscopy.

    PubMed

    Bennett, Jeffery; Chung, Kwok-Hung; Fong, Hanson; Johnson, James; Paranjpe, Avina

    2017-07-01

    Many new rotary files systems have been introduced, however, limited research has been conducted related to the surface irregularities of these files and if these have any effects on the files themselves. Hence, the aim of the present study was to analyze surface irregularities of the ProTaper® Universal rotary files (PTU) and the ProTaper Next™ rotary files (PTN) before and after instrumentation in curved canals. The main objective was to investigate the nature of these irregularities and how they might influence the use and fracture of rotary files during root-canal treatments. The files were examined pre-operatively using a stereomicroscope and scanning electron microscopy(SEM) to analyze surface imperfections and the presence of particles. Mesial roots of forty extracted mandibular molars were selected. Each instrument was used to prepare one of the mesial canals. The files were then rinsed with alcohol, and autoclaved and analyzed again. Of the 80 files used in this study, five files fractured, five files unwound and seven files were curved or bent and they all belonged to the PTU group. Irregularities and debris could be visualized with the SEM on both unused PTU and PTN files. Most of the debris was found associated with deeper milling grooves and defects on the surface of the metal. Surface analysis of the files that were used and sterilized were performed and the SEM images demonstrated organic debris, metal flash, and crack formation and initiation of fractures for both file types. All files showed machining grooves, metal flash, debris, and defects on cutting edges. These irregularities appear to be critical in the accumulation of debris and initiation of fatigue and crack propagation within the NiTi alloy. The accumulation of debris could be a concern due to the potential exchange of organic debris between patients. Key words:ProTaper® Universal, ProTaper Next™, surface characteristics, SEM.

  3. Occurrence of Dentinal Microcracks in Severely Curved Root Canals with ProTaper Universal, WaveOne, and ProTaper Next File Systems.

    PubMed

    Li, Shu-hui; Lu, Ying; Song, Dongzhe; Zhou, Xuedong; Zheng, Qing-hua; Gao, Yuan; Huang, Ding-ming

    2015-11-01

    This study aims to compare the incidence of dentinal microcracks produced by the ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), WaveOne (Dentsply Maillefer), and ProTaper Next (Dentsply Maillefer) file systems during root canal procedures in severely curved canals using a dyeing technique. Sixty extracted human molars with 25° to 40° root curvatures were divided into 3 groups of 20 canals each. ProTaper Universal, WaveOne, and ProTaper Next file systems were used for root canal procedures. Untreated root canals of 60 molars served as negative controls. After preparation, all roots were stained with 1% methylene blue for 24 hours. Roots were then sectioned at the most curved plane and 2 mm below and above the most curved plane with a low-speed saw under cold water. A stereomicroscope was used to inspect dentinal microcracks at 60× magnification, and differences between these 3 instrument groups were analyzed using the chi-square test. The ProTaper Next system induced less complete and incomplete dentinal microcracks compared with the ProTaper Universal and WaveOne systems (P < .05), and there were no significant differences between the ProTaper Universal and WaveOne systems (P > .05). The ProTaper Universal and WaveOne systems induced significantly more complete cracks in the plane 2 mm above the most curved plane compared with either of the other 2 planes (P = .004). The ProTaper Next system induces less dentinal microcracks during root canal procedures in severely curved root canals compared with the ProTaper Universal and WaveOne systems. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  4. Influence of Temperature on Cyclic Fatigue Resistance of ProTaper Gold and ProTaper Universal Rotary Files.

    PubMed

    Plotino, Gianluca; Grande, Nicola M; Mercadé Bellido, Montse; Testarelli, Luca; Gambarini, Gianluca

    2017-02-01

    The aim of this study was to evaluate the cyclic fatigue resistance of ProTaper Universal (PTU; Dentsply Maillefer, Baillagues, Switzerland) and ProTaper Gold (PTG, Dentsply Maillefer) nickel-titanium rotary files at room and intracanal temperatures. A total of 120 files were used to test the cyclic fatigue resistance of PTU (S1 and F2) and PTG (S1 and F2) in an artificial canal at room temperature (20°C) and at intracanal temperature (35°C). The number of cycles to failure and the fracture length of the fragment were recorded, and data were subjected to statistical analysis. PTG registered no differences in fatigue life between the 2 temperatures tested (P > .05), whereas PTU showed a statistically significant reduction in fatigue life at intracanal temperature compared with room temperature (P < .05). PTG instruments exhibited a statistically higher resistance to cyclic fatigue than PTU instruments both at room and intracanal temperatures (P < .05). There were no statistically significant differences among the fracture length of separated instruments (P > .05). Intracanal temperature influenced the cyclic fatigue resistance of instruments produced with traditional nickel-titanium, whereas it did not influence the fatigue life of instruments produced with gold heat treatment. Gold heating treatment enhances the resistance to cyclic fatigue of ProTaper instruments. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  5. Finishing of advanced ceramic balls for bearing applications by magnetic float polishing (MFP) involving fine polishing followed by chemo-mechanical polishing (CMP)

    NASA Astrophysics Data System (ADS)

    Jiang, Ming

    Scope and method of study. This investigation deals with the development of science and technology of finishing advanced ceramics, such as Sisb3Nsb4 balls for bearing applications by magnetic float polishing (MFP) technology. Experimental design and analysis based on Taguchi method are applied to determine the optimum processing conditions for improving the surface quality in fine mechanical polishing by MFP technology. Polishing with various abrasives, different operating conditions, and polishing environments for Sisb3Nsb4 bearing balls have been investigated. Fundamental mechanisms of chemo-mechanical polishing (CMP) have been studied based on thermodynamic and kinetic analysis. Findings and conclusions. The methodology, involved mechanical polishing followed by CMP for finishing of Sisb3Nsb4 balls from the as-received condition to a sphericity of 0.15 mum and surface finish of Ra 4 nm by MFP technology has been developed. It takes about 20 hours to finish a batch of balls compared to a range of several weeks to several months by conventional grinding and polishing technology. High material removal rates (1 mum/min) with minimal subsurface damage are possible by mechanical polishing with harder abrasives such as Bsb4C or SiC in MFP. CeOsb2 and ZrOsb2 are found to be most effective abrasives followed by Fesb2Osb3 and Crsb2Osb3 for CMP of Sisb3Nsb4. CMP is found to be particularly effective in a water-based environment. There are similarities between polishing glass and polishing Sisb3Nsb4 workmaterial including the role of water, polishing environment, and chemical effectiveness and mechanical hardness of abrasive for effective polishing.

  6. Vibration transfer in the ball-stem contact interface of artificial hips.

    PubMed

    Hothan, Arne; Lewerenz, Kathrin; Weiss, Cornelius; Hoffmann, Norbert; Morlock, Michael; Huber, Gerd

    2013-10-01

    Audible squeaking has put the reputation of ceramic bearings for total hip replacements into question. Inter-articular friction induces vibrations in the ceramic head which are transferred through the head-taper interface to the femoral stem. If excited to sufficient amplitudes, squeaking can be emitted by the stem. Hence, the damping and amplification properties of this interface have a crucial influence on stem vibrations. The aim of this study was to determine the vibration transfer behavior between the head and the taper of a femoral stem and its dependence on the assembly force, in order to assess its influence on the development of audible squeaking. A ceramic head was assembled on a titanium femoral stem taper with high and low forces. Frequency response functions characterizing the head-stem interface were determined experimentally. The interface demonstrated negligible influence on vibration transfer in the squeaking frequency range (1-5 kHz). However its damping effect in lower and higher frequency ranges was significant and some areas of amplification were also found. Although squeaking vibration was not influenced by the particular interface studied, the method established can be utilized to trace taper designs with dynamic properties that decrease the susceptibility to squeaking.

  7. Key findings from studies of methotrexate tapering and withdrawal in rheumatoid arthritis.

    PubMed

    Subesinghe, Sujith; Scott, Ian C

    2015-01-01

    Methotrexate is the dominant initial drug in the management of rheumatoid arthritis (RA). Despite its widespread use, methotrexate is associated with a number of adverse effects. Tapering its dose to the minimal amount required to maintain RA remission is, therefore, an important clinical goal. While the complete withdrawal of disease-modifying anti-rheumatic drugs is associated with a definite risk of a disease flare, it is unclear as to what the risk is specific to methotrexate withdrawal and whether this can be minimized by gradual dose reduction (termed 'tapering'). This review examines studies of methotrexate tapering and withdrawal on RA outcomes. It covers three scenarios: tapering/withdrawing methotrexate monotherapy; tapering/withdrawing methotrexate as part of a 'step-down' combination disease-modifying anti-rheumatic drug regimen; and tapering/withdrawing methotrexate when it is being co-prescribed with biologic agents.

  8. Compact and efficient large cross-section SOI rib waveguide taper optimized by a genetic algorithm

    NASA Astrophysics Data System (ADS)

    Liu, Yujin; Wang, Xi; Dong, Ying; Wang, Xiaohao

    2016-01-01

    A genetic algorithm is applied to optimize a taper between a large cross-section silicon-on-insulator (SOI) rib waveguide and a single-mode fiber to achieve an ultra-compact and highly efficient coupling structure. The coupling efficiency is taken as the objective function of the genetic algorithm in the taper optimization process. To apply the optimization algorithm, the taper is segmented into several sections. Three encoding forms and a two-step optimization strategy are adopted in the optimization process, resulting in a 10μm long taper with a coupling efficiency of 93.30% in quasi-TE mode at 1550nm. The characteristics of the optimized taper including the field profile, spectrum and fabrication tolerances in both horizontal and vertical directions are investigated via a three dimensional eigenmode expansion (EME) method, indicating that the optimized taper is compatible with the prevailing integrated circuit (IC) processing technology.

  9. Refractive index sensor based on asymmetrical Mach-Zehnder interferometer with step-like tapers

    NASA Astrophysics Data System (ADS)

    Xia, Feng; Zhao, Yong; Hu, Hai-feng; Chen, Mao-qing; Zhang, Ya-nan

    2017-04-01

    A novel refractive index (RI) sensor based on an asymmetrical Mach-Zehnder interferometer (MZI) with two different step-like tapers is proposed. The step-like taper is fabricated by fusion splicing two half tapers with an appropriate offset. By further applying offset and discharging to the last fabricated step-like taper of MZI, influence of taper parameters on interference spectrum is investigated using only one device. This simple technique provides an on-line method to sweep parameters of step-like tapers and speeds up the optimization process of interference spectrum. In RI sensing experiment, the sensor has a high sensitivity of 187.67 nm/RIU (refractive index unit) in the RI range of 1.3409 - 1.3736.

  10. Dwarf mistletoe does not increase trunk taper in released red firs in California

    Treesearch

    Robert F. Scharpf

    1977-01-01

    Dwarf mistletoe had no noticeable effect on trunk taper of young, dominant and codominant red firs 4 to 22 inches (10.2 to 55.9 cm) d.b.h. Also, taper was not influenced by live crown ratio of infected and uninfected trees. Trees less than 7 inches d.b.h. had significantly more taper than larger trees, irrespective of dwarf mistletoe.

  11. The analysis of fluids by their refractive index using the tapered optical fiber

    NASA Astrophysics Data System (ADS)

    Hackiewicz, Krzysztof; Weremczuk, Jerzy

    2016-09-01

    In this paper, we demonstrate a manufacture of the tapered optical fiber used to analyze the composition or quality of fluid by measuring the external refractive index of the desired analyte. They were made in two ways: using a laser plotter and professional station to do such a tapered fibers. The results prove that utilization of the tapered fiber is really useful to microfluidic domain.

  12. [Significant events in Polish psychiatry in 2003?].

    PubMed

    Bomba, Jacek

    2004-01-01

    The aim of this paper was a reflection on the most significant events in Polish psychiatry in 2003. Reform in health care financing and its realisation in 2003 introduced a risk of inhibiting further development of mental health care. The endangerment is a result of allocation of resources, which is inadequate to real costs and promotes in-patient treatment. An additional risk is seen in a project of privatisation of health care institutions. Increasing orientation towards methodology of molecular biology, which is similar to a general global tendency, influences research in psychiatry. Nevertheless the low number of publications resulting from government sponsored studies is disturbing. The situation in forensic psychiatry calls for involvement and studies. Psychiatria Polska published a report indicating low standard of psychiatric expertise for courts and high probability of corruption. The same was reflected in mass media publications later on. Polish Psychiatric Association Board had appointed a special commission to study this problem.

  13. Characterization of arbitrary fiber taper profiles with optical microscopy and image processing algorithms

    NASA Astrophysics Data System (ADS)

    Farias, Heric D.; Sebem, Renan; Paterno, Aleksander S.

    2014-08-01

    This work reports results from the development of a software to process the parameters involved in the characterization of fiber taper profiles, while using optical microscopy, a high-definition camera and a high- precision translation stage as the moveable base on which the taper is positioned. In addition to this procedure, image processing algorithms were customized to process the acquired images. With edge detection algorithms in the stitched image, one would be able to characterize the given taper radius curve that represents the taper profile when the camera has a sufficient resolution. As a consequence, the proposed fiber taper characterization procedure is a first step towards a high-resolution characterization of fiber taper diameters with arbitrary profiles, specially this case, in which tapers are fabricated with the stepwise technique that allows the production of non- biconical profiles. The parameters of the stitched images depends on the used microscope objective and the length of the characterized tapers. A non-biconical arbitrary taper is measured as an example for the illustration of the developed software and procedure.

  14. Multicolor upconversion emissions in Tm 3+/Er3+ codoped tellurite photonic microwire between silica fiber tapers.

    PubMed

    Chen, Nan-Kuang; Kuan, Pei-Wen; Zhang, Junjie; Zhang, Liyan; Hu, Lili; Lin, Chinlon; Tong, Limin

    2010-12-06

    We report multicolor upconversion emissions including the blue-violet, green, and red lights in a Tm 3+/Er3+codoped tellurite glass photonic microwire between two silica fiber tapers. A silica fiber is tapered until its evanescent field is exposed and then angled-cleaved at the tapered center to divide the tapered fibers into two parts. A tellurite glass is melted by a gas flame to cluster into a sphere at the tip of one tapered fiber. The other angled-cleaved tapered fiber is blended into the melted tellurite glass. When the tellurite glass is melted, the two silica fiber tapers are simultaneously moving outwards to draw the tellurite glass into a microwire in between. The advantage of angled-cleaving on fiber tapers is to avoid cavity resonances in high index photonic microwire. Thus, the broadband white light can be transmitted between silica fibers and a special optical property like high intensity upconversion emission can be achieved. A cw 1064 nm Nd:YAG laser light is launched into the Tm 3+/Er3+ codoped tellurite microwire through a silica fiber taper to generate the multicolor upconversion emissions, including the blue-violet, green, and red lights, simultaneously.

  15. Efficiency and Spectrum Enhancement in a Tapered Free-Electron Laser Amplifier

    SciTech Connect

    Wang, X. J.; Harder, D.; Murphy, J. B.; Qian, H.; Shen, Y.; Yang, X.; Freund, H. P.; Miner, W. H. Jr.

    2009-10-09

    We report the first experimental characterization of efficiency and spectrum enhancement in a laser-seeded free-electron laser using a tapered undulator. Output and spectra in the fundamental and third harmonic were measured versus distance for uniform and tapered undulators. With a 4% field taper over 3 m, a 300% (50%) increase in the fundamental (third harmonic) output was observed. A significant improvement in the spectra with the elimination of sidebands was observed using a tapered undulator. The experiment is in good agreement with predictions using the MEDUSA simulation code.

  16. Efficiency enhancement of coupled-cavity TWT's through cavity resonance tapering

    NASA Technical Reports Server (NTRS)

    Connolly, D. J.

    1979-01-01

    The paper examines efficiency enhancement of coupled-cavity traveling-wave tube (TWT) through cavity resonance tapering. Beam-wave resynchronization through circuit velocity reduction is used for TWT efficiency enhancement, with circuit velocity reduction in coupled cavity TWT's accomplished through period tapering. However, the amount of the latter is limited by the stability considerations, so that beyond a critical value of velocity reduction, the tube may be subject to zero drive oscillations originating in the velocity taper region. The coupled-cavity resonance tapering allows the velocity reduction to continue beyond the limit of stable period tapering, and it is accomplished by a gradual reduction in the cavity resonance frequency, with the period and the circuit bandwidth unchanged. The advantages of cavity resonance tapering vs period tapering are discussed, and test data are presented with the results of large-signal computer calculations. It is shown that cavity resonance tapering can produce efficiencies as period tapering without incurring the same risk of lower band-edge oscillations.

  17. Condensate polishers add operating reliability and flexibility

    SciTech Connect

    Layman, C.M.; Bennett, L.L.

    2008-08-15

    Many of today's advanced steam generators favour either an all-volatile treatment or oxygenated treatment chemistry programme, both of which require strict maintenance of an ultra-pure boiler fedwater ro condensate system. Those requirements are many times at odds with the lower-quality water sources, such as greywater, available for plant makeup and cooling water. Adding a condensate polisher can be a simple, cost-effective solution. 4 figs.

  18. Lacquer polishing of X-ray optics

    NASA Technical Reports Server (NTRS)

    Catura, R. C.; Joki, E. G.; Roethig, D. T.; Brookover, W. J.

    1987-01-01

    Techniques for polishing figured X-ray optics by a lacquer-coating process are described. This acrylic lacquer coating has been applied with an optical quality of an eighth-wave in red light and very effectively covers surface roughness with spatial wavelengths less than about 0.2 mm. Tungsten films have been deposited on the lacquer coatings to provide highly efficient X-ray reflectivity.

  19. [Discontinuation-Emergent Signs and Symptoms Inventory--Polish translation of the discontinuation signs and symptoms checklist].

    PubMed

    Cubała, Wiesław Jerzy; Landowski, Jerzy; Springer, Janusz

    2013-01-01

    A number of preclinical and clinical studies are focused on mechanisms of SSRI discontinuation syndrome as well as the patient populations and agents that are most affected by this phenomenon. Characteristics of onset, duration, and severity of any discontinuation symptoms and spontaneous reports of taper/poststudy-emergent adverse events should be compared with those of the active comparator in these studies. Besides, common clinical practice supplies a number of problems associated with SSRI discontinuation syndrome as related to treatment planning and management. The recommended instrument for evaluating SSRI discontinuation syndrome symptoms is the Discontinuation-Emergent Signs and Symptoms (DESS) inventory. DESS is a 43-item checklist that can be administered in a clinician-rated form, a self-rated form, or an interactive voice-response form. The paper presents the Polish version of DESS inventory along with its application and interpretation instructions. DESS inventory is of substantial advance in common psychiatric practice as it enables effective SSRI discontinuation management on drug tapering and in case of the non-compliance with the treatment. Its use in the systematic studies facilitates conclusive outcome results and is of prime importance as being comparable with literature outcomes.

  20. Duplication of holograms by using fingernail polish

    NASA Astrophysics Data System (ADS)

    Toxqui-López, S.; Olivares-Pérez, A.; Fuentes-Tapia, I.; Quintero-Romo, A.

    2007-08-01

    In this manuscript, we report the results of a research effort in finding an innovative recorder material which utilized fingernail polish (Super Oro One Coat®) information by means of the control of temperature as a parameter induced by hand rubbing. Analogical and computer holograms were replicated, resulting in a high quality behavior of fingernail polish through coating the polish with an average thickness of 10-15 μm, which contains some components of polyester resin with nitrocellulose. Through this material we obtained a high absolute diffraction efficiency, which was approximately equal to 90%, with gratings of 100 lines/mm. For a copy of conventional holograms at high frequencies (holographic ranges) the diffraction efficiency parameter is in the neighborhood of 22% at first order or more, depending on diffraction efficiency of the pattern of the hologram. The hologram is elaborated in the absence of any development of any process and does not need to have carefully controlled environmental conditions. Following this process, the hologram is obtained at standard atmospheric conditions of pressure and temperature. Another advantage is that it is possible to obtain a hologram at a lower cost; furthermore, the property of applicability to any substrate that it has is remarkable.

  1. ROUGHNESS ANALYSIS OF VARIOUSLY POLISHED NIOBIUM SURFACES

    SciTech Connect

    Ribeill, G.; Reece, C.

    2008-01-01

    Niobium superconducting radio frequency (SRF) cavities have gained widespread use in accelerator systems. It has been shown that surface roughness is a determining factor in the cavities’ effi ciency and maximum accelerating potential achievable through this technology. Irregularities in the surface can lead to spot heating, undesirable local electrical fi eld enhancement and electron multipacting. Surface quality is typically ensured through the use of acid etching in a Buffered Chemical Polish (BCP) bath and electropolishing (EP). In this study, the effects of these techniques on surface morphology have been investigated in depth. The surface of niobium samples polished using different combinations of these techniques has been characterized through atomic force microscopy (AFM) and stylus profi lometry across a range of length scales. The surface morphology was analyzed using spectral techniques to determine roughness and characteristic dimensions. Experimentation has shown that this method is a valuable tool that provides quantitative information about surface roughness at different length scales. It has demonstrated that light BCP pretreatment and lower electrolyte temperature favors a smoother electropolish. These results will allow for the design of a superior polishing process for niobium SRF cavities and therefore increased accelerator operating effi ciency and power.

  2. Multiwavelength digital holography for polishing tool shape measurement

    NASA Astrophysics Data System (ADS)

    Lédl, Vít.; Psota, Pavel; Václavík, Jan; Doleček, Roman; Vojtíšek, Petr

    2013-09-01

    Classical mechano-chemical polishing is still a valuable technique, which gives unbeatable results for some types of optical surfaces. For example, optics for high power lasers requires minimized subsurface damage, very high cosmetic quality, and low mid spatial frequency error. One can hardly achieve this with use of subaperture polishing. The shape of the polishing tool plays a crucial role in achieving the required form of the optical surface. Often the shape of the polishing tool or pad is not known precisely enough during the manufacturing process. The tool shape is usually premachined and later is changed during the polishing procedure. An experienced worker could estimate the shape of the tool indirectly from the shape of the polished element, and that is why he can achieve the required shape in few reasonably long iterative steps. Therefore the lack of the exact tool shape knowledge is tolerated. Sometimes, this indirect method is not feasible even if small parts are considered. Moreover, if processes on machines like planetary (continuous) polishers are considered, the incorrect shape of the polishing pad could extend the polishing times extremely. Every iteration step takes hours. Even worse, polished piece could be wasted if the pad has a poor shape. The ability of the tool shape determination would be very valuable in those types of lengthy processes. It was our primary motivation to develop a contactless measurement method for large diffusive surfaces and demonstrate its usability. The proposed method is based on application of multiwavelength digital holographic interferometry with phase shift.

  3. Flexibility of K3 and ProTaper universal instruments.

    PubMed

    Grazziotin-Soares, Renata; Barato Filho, Flares; Vanni, José Roberto; Almeida, Susimara; Oliveira, Elias Pandonor Motcy de; Barletta, Fernando Branco; Limongi, Orlando

    2011-01-01

    This study used a mechanical test to evaluate the flexibility of instruments from the K3 (conicity 0.04) and the ProTaper Universal systems when they were new and after 5 uses in simulated canals. Five sets of instruments of each system were tested: K3 (15, 20, 25, 30, 35, 40 and 45) and ProTaper Universal (S1, S2, F1, F2, F3, F4 and F5). Each set of instruments was used to prepare a simulated canal and the same set of instruments was used 5 times (50 canals). The number of each subgroup represented the number of uses: 0 (control), 1, 3 and 5 uses. Before and after each use, the instruments were submitted to a mechanical flexibility test performed in a Versat 502 universal testing machine. Interactions between the instrument and the number of uses were analyzed by ANOVA and Tukey's test at a 5% level of significance. Instruments from both systems presented lower flexibility after the third use compared to the flexibility obtained after uses 0 and 1 (p<0.05), and maintained the same flexibility after the fifth use. The flexibility of instruments from the K3 system decreased with the increase of diameter, irrespective of the number of uses. Among the instruments from the ProTaper Universal system, the shaping files presented greater flexibility than the finishing files. F2 and F3 were the least flexible instruments, and F4 and F5 presented flexibility values similar to those of F1.

  4. Multimaterial preform coextrusion for robust chalcogenide optical fibers and tapers.

    PubMed

    Tao, Guangming; Shabahang, Soroush; Banaei, Esmaeil-Hooman; Kaufman, Joshua J; Abouraddy, Ayman F

    2012-07-01

    The development of robust infrared fibers is crucial for harnessing the capabilities of new mid-infrared lasers. We present a novel approach to the fabrication of chalcogenide glass fiber preforms: one-step multimaterial extrusion. The preform consists of a glass core and cladding surrounded by a built-in, thermally compatible, polymer jacket for mechanical support. Using this approach we extrude several preform structures and draw them into robust composite fibers. Furthermore, the polymer cladding allows us to produce robust tapers with submicrometer core diameter.

  5. Method of making tapered capillary tips with constant inner diameters

    SciTech Connect

    Kelly, Ryan T.; Page, Jason S.; Tang, Keqi; Smith, Richard D.

    2009-02-17

    Methods of forming electrospray ionization emitter tips are disclosed herein. In one embodiment, an end portion of a capillary tube can be immersed into an etchant, wherein the etchant forms a concave meniscus on the outer surface of the capillary. Variable etching rates in the meniscus can cause an external taper to form. While etching the outer surface of the capillary wall, a fluid can be flowed through the interior of the capillary tube. Etching continues until the immersed portion of the capillary tube is completely etched away.

  6. 1.3 micron polarization insensitive tapered waveguide devices

    NASA Astrophysics Data System (ADS)

    Uppal, Kushant

    This work discusses the details of MOCVD growth, characterization and fabrication of 1.3mum tapered waveguide polarization insensitive devices. Compressive, tensile and lattice matched material was first developed. Broad area lasers with 3 compressive strained quantum wells (QWs) have a threshold current density (Jsbth) of 234A/cmsp2 and with 3 tensile QWs have a Jsbth of 277A/cmsp2 which are comparable to the best values reported in the literature. Polarization insensitive devices with active regions containing both tensile and compressive QWs were then developed using an edge photoluminescence characterization technique. This technique is useful in matching the wavelengths of the TE and TM modes which is an important requirement for obtaining dual polarization characteristics. Broad area lasers fabricated from these materials demonstrated dual polarization lasing characteristics and the amplifiers obtained after AR coating the facets had polarization insensitivity of about 1dB between the TE and TM modes. Tapered waveguide buried heterostructure devices with mixed quantum well (MQW) active regions were then developed using a combination of wet and dry ECR etching which is much simpler than any of the techniques used today for obtaining spot-size transformation. Threshold currents as low as 20mA were obtained for the MQW devices. Single mode far-field FWHM angle reduction of about 12sp°{-}15sp° were obtained in both the lateral and vertical directions. This results in a 4dB improvement of the coupling efficiency of the tapered end over the untapered end of the device. A waveguide loss calculation based on experimental data was done to find the excess loss due to the tapered section of the waveguide. InGaP based 0.98mum and 0.8mum short wavelength broad are lasers were also studied. The effect of the waveguide layer on the device characteristics was examined in the case of the 0.98mum lasers. Low threshold current densities of 72A/cmsp2 were achieved for these

  7. Nanocoating effects on tapered long period fiber gratings

    NASA Astrophysics Data System (ADS)

    Pilla, P.; Cusano, A.; Cutolo, A.; Giordano, M.; Korwin-Pawlowski, M. L.; Bock, W. J.

    2007-07-01

    In this work, the experimental analysis of the response of nanocoated Tapered Long Period Gratings (TLPGs) to Surrounding Refractive Index (SRI) changes is presented. The modal transition is demonstrated to take place in this kind of devices and to be an effective method to improve their SRI sensitivity. The dip-coating method was carried out by an automated system and showed to be a reliable technique for the deposition of conformal coatings. A comparison with traditional UV-written LPGs revealed that a thicker overlay is necessary for the TLPG to tune the transition region in the same SRI range.

  8. X-Ray Propagation in Tapered Planar Waveguide

    NASA Astrophysics Data System (ADS)

    Dolocan, Andrei; van der Veen, J. Friso

    The present paper focuses on the tapered planar waveguide solution for an initial given wave form. The algorithm is constructed in distributions space such that the calculations can be actually computed by taking some hypothesis regarding the mode series which appear. The whole argument leads to the conclusion that the wave is compressed towards the waveguide in the direction of tilting, leading thereafter to a focusing phenomena. We present two alternative constructions in order to compute the convolution which gives the wave inside the waveguide. The hypothesis are providing results in good approximation with the real evolution of the field within the definition domain.

  9. FEL GAIN LENGTH AND TAPER MEASUREMENTS AT LCLS

    SciTech Connect

    Ratner, D.; Fawley, W. M.; Brachmann, A.; Decker, F.J.; Ding, Y.; Dowell, D.; Emma, P.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, P.; Huang, Z.; Loos, H.; Miahnahri, A.; Nuhn, H.D.; Turner, J.; Welch, J.; White, W.; Wu, J.; Xiang, D.; Yocky, G.; Fawley, W. M.

    2009-08-14

    We present experimental studies of the gain length and saturation power level from 1.5 nm to 1.5 Angstroms at the Linac Coherent Light Source (LCLS). By disrupting theFEL process with an orbit kick, we are able to measure the X-ray intensity as a function of undulator length. This kick method is cross-checked with the method of removing undulator sections. We also study the FEL-induced electron energy loss after saturation to determine the optimal taper of the undulator K values. The experimental results are compared to theory and simulations.

  10. FEL Gain Length and Taper Measurements at LCLS

    SciTech Connect

    Ratner, Daniel; Brachmann, A.; Decker, F.J.; Ding, Y.; Dowell, D.; Emma, P.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, P.; Huang, Z.; Iverson, R.; Loos, H.; Miahnahri, A.; Nuhn, H.D.; Turner, J.; Welch, J.; White, W.; Wu, J.; Xiang, D.; Yocky, G.; /SLAC /LBL, Berkeley

    2010-07-30

    We present experimental studies of the gain length and saturation power level from 1.5 nm to 1.5 {angstrom} at the Linac Coherent Light Source (LCLS). By disrupting the FEL process with an orbit kick, we are able to measure the X-ray intensity as a function of undulator length. This kick method is cross-checked with the method of removing undulator sections. We also study the FEL-induced electron energy loss after saturation to determine the optimal taper of the undulator K values. The experimental results are compared to theory and simulations.

  11. Modeling taper charge with a non-linear equation

    NASA Technical Reports Server (NTRS)

    Mcdermott, P. P.

    1985-01-01

    Work aimed at modeling the charge voltage and current characteristics of nickel-cadmium cells subject to taper charge is presented. Work reported at previous NASA Battery Workshops has shown that the voltage of cells subject to constant current charge and discharge can be modeled very accurately with the equation: voltage = A + (B/(C-X)) + De to the -Ex where A, B, D, and E are fit parameters and x is amp-hr of charge removed during discharge or returned during charge. In a constant current regime, x is also equivalent to time on charge or discharge.

  12. Design and Manufacture of Structurally Efficient Tapered Struts

    NASA Technical Reports Server (NTRS)

    Brewster, Jebediah W.

    2009-01-01

    Composite materials offer the potential of weight savings for numerous spacecraft and aircraft applications. A composite strut is just one integral part of the node-to-node system and the optimization of the shut and node assembly is needed to take full advantage of the benefit of composites materials. Lockheed Martin designed and manufactured a very light weight one piece composite tapered strut that is fully representative of a full scale flight article. In addition, the team designed and built a prototype of the node and end fitting system that will effectively integrate and work with the full scale flight articles.

  13. Continuously tunable delay line based on SOI tapered Bragg gratings.

    PubMed

    Giuntoni, Ivano; Stolarek, David; Kroushkov, Dimitar I; Bruns, Jürgen; Zimmermann, Lars; Tillack, Bernd; Petermann, Klaus

    2012-05-07

    The realization of an integrated delay line using tapered Bragg gratings in a drop-filter configuration is presented. The device is fabricated on silicon-on-insulator (SOI) rib waveguides using a Deep-UV 248 nm lithography. The continuous delay tunability is achieved using the thermo-optical effect, showing experimentally that a tuning range of 450 ps can be obtained with a tuning coefficient of -51 ps/°C. Furthermore the system performance is considered, showing that an operation at a bit rate of 25 Gbit/s can be achieved, and could be extended to 80 Gbit/s with the addition of a proper dispersion compensation.

  14. Space Power Amplification with Active Linearly Tapered Slot Antenna Array

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1993-01-01

    A space power amplifier composed of active linearly tapered slot antennas (LTSA's) has been demonstrated and shown to have a gain of 30 dB at 20 GHz. In each of the antenna elements, a GaAs monolithic microwave integrated circuit (MMIC) three-stage power amplifier is integrated with two LTSA's. The LTSA and the MMIC power amplifier has a gain of 11 dB and power added efficiency of 14 percent respectively. The design is suitable for constructing a large array using monolithic integration techniques.

  15. On-chip optical mode exchange using tapered directional coupler

    PubMed Central

    Zhang, Zhonglai; Hu, Xiao; Wang, Jian

    2015-01-01

    We present an on-chip optical mode exchange between two multiplexed modes by using tapered directional couplers on silicon-on-insulator platform. The device consisting of mode multiplexing and mode exchange is compact with relatively large fabrication error tolerance. The simulation results show efficient higher order mode excitation and mode exchange. A low excess loss less than 0.5 dB and high extinction ratio larger than 15 dB over 10 nm wavelength range from 1535 to 1545 nm are achieved. PMID:26530728

  16. Abrupt fiber taper based Michelson interferometric deflection sensor

    NASA Astrophysics Data System (ADS)

    Tian, Zhaobing; Yam, Scott S.-H.

    2008-06-01

    A new compact standard single mode fiber Michelson interferometer deflection sensor was proposed, tested and simulated. The new interferometer consists of a symmetrical abrupt 3 dB taper region with a 40 μm waist diameter, a 700 μm length and a 500nm thick gold layer coating. Compared with similar interferometric devices based on long period gratings that need microfabrication technology and photosensitive fibers, the proposed sensor uses a much simplified fabrication process and normal single mode fiber, and has a linear response of 1.1nm/mm.

  17. Spatial frequency multiplier with active linearly tapered slot antenna array

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1994-01-01

    A frequency multiplier with active linearly tapered slot antennas (LTSA's) has been demonstrated at the second harmonic frequency. In each antenna element, a GaAs monolithic microwave integrated circuit (MMIC) distributed amplifier is integrated with two LTSA's. The multiplier has a very wide bandwidth and large dynamic range. The fundamental-to-second harmonic conversion efficiency is 8.1 percent. The spatially combined second harmonic signal is 50 dB above the noise level. The design is suitable for constructing a large array using monolithic integration techniques.

  18. Characterization of tapered slot antenna feeds and feed arrays

    NASA Technical Reports Server (NTRS)

    Kim, Young-Sik; Yngvesson, K. Sigfrid

    1990-01-01

    A class of feed antennas and feed antenna arrays used in the focal plane of paraboloid reflectors and exhibiting higher than normal levels of cross-polarized radiation in the diagonal planes is addressed. A model which allows prediction of element gain and aperture efficiency of the feed/reflector system is presented. The predictions are in good agreement with experimental results. Tapered slot antenna (TSA) elements are used an example of an element of this type. It is shown that TSA arrays used in multibeam systems with small beam spacings are competitive in terms of aperture efficiency with other, more standard types of arrays incorporating waveguide type elements.

  19. Gaussian Filtering with Tapered Oil-Filled Photonic Bandgap Fibers

    NASA Astrophysics Data System (ADS)

    Brunetti, A. C.; Scolari, L.; Weirich, J.; Eskildsen, L.; Bellanca, G.; Bassi, P.; Bjarklev, A.

    2008-10-01

    A tunable Gaussian filter based on a tapered oil-filled photonic crystal fiber is demonstrated. The filter is centered at λ = 1364 nm with a bandwidth (FWHM) of 237nm. Tunability is achieved by changing the temperature of the filter. A shift of 210nm of the central wavelength has been observed by increasing the temperature from 25 °C to 100 °C. The measurements are compared to a simulated spectrum obtained by means of a vectorial Beam Propagation Method model.

  20. Embryonic body formation using the tapered soft stencil for cluster culture device.

    PubMed

    Yukawa, Hiroshi; Ikeuchi, Masashi; Noguchi, Hirofumi; Miyamoto, Yoshitaka; Ikuta, Koji; Hayashi, Shuji

    2011-05-01

    Induced pluripotent stem (iPS) cells are expected to provide a source of tissue, a renewable cell source for tissue engineering, and a method for in vitro drug screening for patient-specific or disease-specific treatment. A simple technology by which iPS cells can be differentiated effectively and in large quantities is strongly desired. In this paper, a new device (Tapered Soft Stencil for Cluster Culture: TASCL) is proposed for the easy and efficient formation of EBs which can be used in regenerative medicine. This device was compared with the two major methods currently being evaluated, namely the HD method and the Terasaki® plate (MWC substitution), in terms of the efficiency, morphology and acquired number of EB formation. Using the TASCL device, the shape of the EBs formed was almost a perfect sphere, and the formation was also faster than for the two other methods. There was little variability in the number of cells. Moreover, EBs formed using the TASCL device had the ability to differentiate into all three germ layers, and differentiation of EBs from the TASCL culture into hepatic cells was confirmed. In conclusion, it appears that the TASCL device can be utilized for EB formation to generate cells for regenerative medicine applications.

  1. Polishing performances of different optics with different size powder and different pH value slurries during CMP polishing

    NASA Astrophysics Data System (ADS)

    Cao, Jun; Wei, Chaoyang; Liu, Shijie; Dun, Aihuan; Yang, Minghong; Xu, Xueke; Shao, Jianda

    2015-10-01

    Different size polishing powder and different pH value ceria slurries were used to polish fused silica glass K9 glass and Nd-doped glass on pitch plate. Material removal rates (MRR) of glass polished with different size powder and various pH value slurries, and textures of each sample were characterized. The results show that powder size has an effect on glass polishing performance: scratch densities increase with the increase of polishing powder size; surface textures become rougher with the increase of the size of polishing powder. The slurry pH value also affects glass polishing performance: MRR of fused silica glass are lowest under any pH value slurry while Nd-doped glass has the largest MRR; removal rates of all three kinds of glass will rise under both acidic and alkaline condition. Near neutral polishing environment and smaller size powder are useful for the surface polishing process. The results further reveal polishing mechanism and provide the guidance for glass surface process.

  2. Patients' Perspectives on Tapering of Chronic Opioid Therapy: A Qualitative Study.

    PubMed

    Frank, Joseph W; Levy, Cari; Matlock, Daniel D; Calcaterra, Susan L; Mueller, Shane R; Koester, Stephen; Binswanger, Ingrid A

    2016-10-01

    OBJECTIVE : There is inadequate evidence of long-term benefit and growing evidence of the risks of chronic opioid therapy (COT). Opioid dose reduction, or opioid tapering, may reduce these risks but may also worsen pain and quality of life. Our objective was to explore patients' perspectives on opioid tapering. DESIGN : Qualitative study using in-person, semistructured interviews. SETTING AND PATIENTS : English-speaking, adult primary care patients (N = 24) in three Colorado health care systems. METHODS : Interviews were audio recorded, transcribed, and analyzed in ATLAS.ti. We used a team-based, mixed inductive and deductive approach guided by the Health Belief Model. We iteratively refined emergent themes with input from a multidisciplinary team. RESULTS : Participants had a mean age of 52 years old, were 46% male and 79% white. Six participants (25%) were on COT and not tapering, 12 (50%) were currently tapering COT, and 6 (25%) had discontinued COT. Emergent themes were organized in four domains: risks, barriers, facilitators, and benefits. Patients perceived a low risk of overdose and prioritized the more immediate risk of increased pain with opioid tapering. Barriers included a perceived lack of effectiveness of nonopioid options and fear of opioid withdrawal. Among patients with opioid tapering experience, social support and a trusted health care provider facilitated opioid tapering. These patients endorsed improved quality of life following tapering. CONCLUSIONS : Efforts to support opioid tapering should elicit patients' perceived barriers and seek to build on relationships with family, peers, and providers to facilitate tapering. Future work should identify patient-centered, feasible strategies to support tapering of COT. © 2016 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. FEM simulation of the material removal in pad polishing

    NASA Astrophysics Data System (ADS)

    Almeida, R.; Börret, R.; Rimkus, W.; Harrison, D.; DeSilva, A.

    2017-06-01

    Polishing as a step of the manufacturing process is not only used in the finishing of optical elements made out of glass. An increasing number of applications needs shiny or glossy surfaces. For these parts, the specified roughness has to be achieved by a final polishing step while keeping or improving the final shape. The goal of the presented research is to predict the material removal that occurs during the polishing process by a simulation based on finite element modelling (FEM). The presented finite element simulation model for PMMA is based on the material parameters for workpiece and polishing tool. Compared to previous research on aspherical elements made out of glass [1], the model allows the description of the process based on material parameters get out the data sheets. The data derived from the finite element modelling is compared with the polishing results on plastic materials (PMMA). Results of the polishing tests compared with the simulated values will be reported.

  4. CO2 laser polishing of conical shaped optical fiber deflectors

    NASA Astrophysics Data System (ADS)

    Şimşek, Elif Uzcengiz; Şimşek, Bartu; Ortaç, Bülend

    2017-06-01

    A novel method for polishing conical shaped optical fiber deflectors by modulated CO2 laser exposure is reported. The conical shaped fiber deflector geometry was first formed with rough mechanical polishing, then it was exposed to modulated CO2 laser operating with wavelength at 10.6 µm to achieve fine polish surfaces. The motivation of this work is to demonstrate that the modulated CO2 laser exposure approach allows a fiber surface roughness at a nanometer scale without modifying the conical shape of the fiber deflector. The average surface roughness of mechanically polished fiber deflectors with 30 and 9 µm lapping films was smoothed down to 20.4 and 4.07 nm, respectively, after CO2 laser polishing process. By combining mechanical and laser polishing techniques, fabrication of conical shaped optical fiber deflectors takes less time and it becomes laborer independent and easy to apply.

  5. The advancement of the high precision stress polishing

    NASA Astrophysics Data System (ADS)

    Li, Chaoqiang; Lei, Baiping; Han, Yu

    2016-10-01

    The stress polishing is a kind of large-diameter aspheric machining technology with high efficiency. This paper focuses on the principle, application in the processing of large aspheric mirror, and the domestic and foreign research status of stress polishing, aimed at the problem of insufficient precision of mirror surface deformation calculated by some traditional theories and the problem that the output precision and stability of the support device in stress polishing cannot meet the requirements. The improvement methods from these three aspects are put forward, the characterization method of mirror's elastic deformation in stress polishing, the deformation theory of influence function and the calculation of correction force, the design of actuator's mechanical structure. These improve the precision of stress polishing and provide theoretical basis for the further application of stress polishing in large-diameter aspheric machining.

  6. Corrosion and Fretting of a Modular Hip System: A Retrieval Analysis of 60 Rejuvenate Stems.

    PubMed

    De Martino, Ivan; Assini, Joseph B; Elpers, Marcella E; Wright, Timothy M; Westrich, Geoffrey H

    2015-08-01

    Femoral stems with dual-taper modularity were introduced to allow independent control of length, offset, and version. Corrosion and fretting related to micromotion at the neck-stem junction are thought to stimulate an adverse local tissue reaction (ALTR). Analysis of 60 consecutively retrieved modular-neck stem implants (Rejuvenate, Stryker) revised primarily for ALTR was done to determine the variables influencing corrosion and fretting patterns at the neck-stem interface. Taper damage evaluation was performed with stereomicrocopic analysis with two observers. Evidence of fretting and corrosion was seen at the neck-stem taper in all implants, including three implants revised for periprosthetic fractures within four weeks of the index surgery indicating that this process starts early. Femoral stems paired with the long overall neck lengths had significantly higher corrosion scores. Correlation of the corrosion severity at particular locations with the length of implantation suggests that the neck-stem junction experiences cyclic cantilever bending in vivo. The positive correlation between the length of implantation and fretting/corrosion scores bodes poorly for patients who still have this implant. Scanning electron microscopy on a subset of specimens was also performed to evaluate the black corrosion material. We strongly urge frequent follow-up exams for every patient with this particular modular hip stem.

  7. Wet gas measure by tapered tube variable area ring orifice

    NASA Astrophysics Data System (ADS)

    Xue, Guomin; Shen, Yi

    2008-10-01

    Great difficulties exist in wet gas flow measuring by means of standard orifice plate since the rangeability can only reach 3:1, with serious pressure loss plus liquid aggregation near the upstream orifice plate. Therefore, it is necessary to improve the structure of the standard orifice plate. This paper presents a sort of tapered tube variable area ring orifice device for wet gas measure, which is designed structurally by combination of a tapered tube, an inner circle-shaped movable baffle, a precision spring and a displacement sensor. Accordingly, a wet gas flow equation is shown that features the substitution of displacement for pressure difference. The rangeability can be as large as 15:1 in the case that the area ratio of the variable flow path is designed to be 5:1. The hydromechanical numerical simulation results indicate that both rate field and pressure field inside the device are stable and the pressure loss is one-third of the standard orifice plate. Further, the problems of liquid aggregation and pressure ducts block are avoided.H

  8. Fatigue Life Methodology for Tapered Hybrid Composite Flexbeams

    NASA Technical Reports Server (NTRS)

    urri, Gretchen B.; Schaff, Jeffery R.

    2006-01-01

    Nonlinear-tapered flexbeam specimens from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. Two different graphite/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) associated with simulated delamination growth in the flexbeams are presented from both codes. These results compare well with each other and suggest that the initial delamination growth from the tip of the ply-drop toward the thick region of the flexbeam is strongly mode II. The peak calculated G values were used with material characterization data to calculate fatigue life curves for comparison with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared well with the test results.

  9. Spiralling tapered slip-on drill string stabilizer

    SciTech Connect

    Beasley, T.R.; Teng, C.C.

    1986-12-23

    A stabilizer is described for use in a drilling string comprising: a substantially cylindrical body member having a central passageway to accommodate the drill sting, the inside surface of the body member defining a right-hand spiralling thread with a tapered trailing edge which spirals from a starting point on the body member. The thread terminates internally of the body member in an arcuate recess extending around the interior of the body member; a key member is secured to the inner wall surface of the recess of the body member, the key member having a lug extending longitudinally of the body member within the recess; a slip member adapted to thread within the body member between the body member and the drill string. The slip defines a right-hand thread with a matching tapered trailing edge configured to make up with the right-hand thread on the body member and to wedge between the body member and the drill string. One end of the slip terminates in a longitudinally disposed shoulder capable of abutting the lug upon threading of the clip within the body member.

  10. Moment method analysis of linearly tapered slot antennas

    NASA Technical Reports Server (NTRS)

    Koeksal, Adnan

    1993-01-01

    A method of moments (MOM) model for the analysis of the Linearly Tapered Slot Antenna (LTSA) is developed and implemented. The model employs an unequal size rectangular sectioning for conducting parts of the antenna. Piecewise sinusoidal basis functions are used for the expansion of conductor current. The effect of the dielectric is incorporated in the model by using equivalent volume polarization current density and solving the equivalent problem in free-space. The feed section of the antenna including the microstripline is handled rigorously in the MOM model by including slotline short circuit and microstripline currents among the unknowns. Comparison with measurements is made to demonstrate the validity of the model for both the air case and the dielectric case. Validity of the model is also verified by extending the model to handle the analysis of the skew-plate antenna and comparing the results to those of a skew-segmentation modeling results of the same structure and to available data in the literature. Variation of the radiation pattern for the air LTSA with length, height, and taper angle is investigated, and the results are tabulated. Numerical results for the effect of the dielectric thickness and permittivity are presented.

  11. Fatigue Life Analysis of Tapered Hybrid Composite Flexbeams

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.; Schaff, Jeffery R.; Dobyns, Alan L.

    2002-01-01

    Nonlinear-tapered flexbeam laminates from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. The two different graphite/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) obtained from the above codes using the virtual crack closure technique (VCCT) at a resin crack location in the flexbeams are presented for both hybrid material types. These results compare well with each other and suggest that the initial delamination growth from the resin crack toward the thick region of the flexbeam is strongly mode II. The peak calculated G values were used with material characterization data to calculate fatigue life curves and compared with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared reasonably well with the test results.

  12. Ultra-abrupt tapered fiber Mach-Zehnder interferometer sensors.

    PubMed

    Li, Benye; Jiang, Lan; Wang, Sumei; Zhou, Lanying; Xiao, Hai; Tsai, Hai-Lung

    2011-01-01

    A fiber inline Mach-Zehnder interferometer (MZI) consisting of ultra-abrupt fiber tapers was fabricated through a new fusion-splicing method. By fusion-splicing, the taper diameter-length ratio is around 1:1, which is much greater than those (1:10) made by stretching. The proposed fabrication method is very low cost, 1/20-1/50 of those of LPFG pair MZI sensors. The fabricated MZIs are applied to measure refractive index, temperature and rotation angle changes. The temperature sensitivity of the MZI at a length of 30 mm is 0.061 nm/°C from 30-350 °C. The proposed MZI is also used to measure rotation angles ranging from 0° to 0.55°; the sensitivity is 54.98 nm/°. The refractive index sensitivity is improved by 3-5 fold by fabricating an inline micro-trench on the fiber cladding using a femtosecond laser. Acetone vapor of 50 ppm in N(2) is tested by the MZI sensor coated with MFI-type zeolite thin film. The proposed MZI sensors are capable of in situ detection in many areas of interest such as environmental management, industrial process control, and public health.

  13. Improved oil-off survivability of tapered roller bearings

    NASA Technical Reports Server (NTRS)

    Kreider, Gary E.; Lee, Peter W.

    1987-01-01

    The aim of this program is to improve the oil-off survivability of a tapered roller bearing when applied to a helicopter transmission, since the tapered bearing has shown a performance advantage in this application. However, the critical roller end-rib conjunction is vulnerable to damage in an oil-off condition. Three powdered metal materials were selected to use as the rib material for oil-off evaluation. These were: M2 steel to a 65% density, CBS 1000M 65% density, and CBS 1000M 75% density. The bearing styles tested were ribbed cone (inner race) and ribbed cup (outer race). Carburized solid CBS 600 was also used as a ribbed material for comparison of oil-off results. The tests were conducted at six speeds from 4000 rpm (0.26 million DN) through 37000 rpm (2.4 million DN).The ribbed cup style bearing achieved longer lives than the ribbed cone style. A standard bearing lasted only 10 minutes at 4000 rpm; however, the 30-min oil-off goal was achieved through 11000 rpm using the survivable ribbed cup bearing. The oil-off lives at 37000 rpm were less than 10 seconds. The grinding of the powder metal materials and surface preparation to achieve an open porosity is extremely critical to the oil-off performance of the powder metal component.

  14. Analysis of guided wave propagation in a tapered composite panel

    NASA Astrophysics Data System (ADS)

    Wandowski, Tomasz; Malinowski, Pawel; Moll, Jochen; Radzienski, Maciej; Ostachowicz, Wieslaw

    2015-03-01

    Many studies have been published in recent years on Lamb wave propagation in isotropic and (multi-layered) anisotropic structures. In this paper, adiabatic wave propagation phenomenon in a tapered composite panel made out of glass fiber reinforced polymers (GFRP) will be considered. Such structural elements are often used e.g. in wind turbine blades and aerospace structures. Here, the wave velocity of each wave mode does not only change with frequency and the direction of wave propagation. It further changes locally due to the varying cross-section of the GFRP panel. Elastic waves were excited using a piezoelectric transducer. Full wave-field measurements using scanning Laser Doppler vibrometry have been performed. This approach allows the detailed analysis of elastic wave propagation in composite specimen with linearly changing thickness. It will be demonstrated here experimentally, that the wave velocity changes significantly due to the tapered geometry of the structure. Hence, this work motivates the theoretical and experimental analysis of adiabatic mode propagation for the purpose of Non-Destructive Testing and Structural Health Monitoring.

  15. Fatigue Life Analysis of Tapered Hybrid Composite Flexbeams

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.; Schaff, Jeffery R.; Dobyns, Alan L.

    2002-01-01

    Nonlinear-tapered flexbeam laminates from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. The two different graphite/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) obtained from the above codes using the virtual crack closure technique (VCCT) at a resin crack location in the flexbeams are presented for both hybrid material types. These results compare well with each other and suggest that the initial delamination growth from the resin crack toward the thick region of the flexbeam is strongly mode II. The peak calculated G values were used with material characterization data to calculate fatigue life curves and compared with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared reasonably well with the test results.

  16. Tapered fluidized bed bioreactor for environmental control and fuel production

    SciTech Connect

    Scott, C. D.; Hancher, C. W.; Arcuri, E. J.

    1980-01-01

    Fluidized bed bioreactors are under development for use in environmental control and energy production. The most effective systems utilize a tapered portion either throughout the column or at the top of the column. This taper allows a wide range of operating conditions without loss of the fluidized particulates, and in general, results in more stable operation. The system described here utilize fixed films of microorganisms that have attached themselves to the fluidized particles. Preliminary investigations of the attachment indicate that reactor performance is related to film thickness. The biological denitrification of aqueous waste streams is typical of processes under development that utilize fluidized bed bioreactors. This development has progressed to the pilot plant scale where two 20-cm-diam x 800-cm fluidized beds in series accept aqueous wastes with nitrate concentrations as high as 10,000 mg/l and denitrification rates greater than 50 g/l/day using residence times of less than 30 minutes in each reactor. Other applications include aerobic degradation of phenolic wastes at rates greater than 25 g/l/day and the conversion of glucose to ethanol.

  17. Constellation-X Cylinder Figuring and Polishing Studies

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Arsenovic, Petar; Content, David; Saha, Timo; Strojny, Carl; Wright, Geraldine; Fleetwood, Charles

    2001-01-01

    In support of Goddard's Constellation-X mandrel manufacturing effort a series of fabrication experiments are being performed to determine a best approach. Currently, polishing immediately after diamond turning, produces a RMS surface roughness of 0.31 nm, on a nickel plated aluminum mandrel. Studies currently under way will incorporate an abrasive figuring step followed by a polishing operation. The current diamond turning, figuring and polishing procedures will be described and the results presented.

  18. Performance analysis of CO2 laser polished angled ribbon fiber

    NASA Astrophysics Data System (ADS)

    Sohn, Ik-Bu; Choi, Hun-Kook; Noh, Young-Chul; Lee, Man-Seop; Oh, Jin-Kyoung; Kim, Seong-min; Ahsan, Md. Shamim

    2017-01-01

    This paper demonstrates CO2 laser assisted simultaneous polishing of angled ribbon fibers consisting eight set of optical fibers. The ribbon fibers were rotated vertically at an angle of 12° and polished by repetitive irradiation of CO2 laser beam at the end faces of the fibers. Compared to mechanically polished sharp edged angled fibers, CO2 laser polishing forms curve edged angled fibers. Increase in the curvature of the end faces of the ribbon fibers causes the increase of the fibers' strength, which in turn represents great robustness against fiber connections with other devices. The CO2 laser polished angled fibers have great smoothness throughout the polished area. The smoothness of the fiber end faces have been controlled by varying the number of laser irradiation. After CO2 laser polishing, the average value of the fiber angle of the ribbon fibers is ∼8.28°. The laser polished ribbon fibers show low insertion and return losses when connecting with commercial optical communication devices. The proposed technique of polishing the angled ribbon fibers is highly replicable and reliable and thus suitable for commercial applications.

  19. Defect centers in chemical-mechanical polished MOS oxides

    SciTech Connect

    Shaneyfelt, M.R.; Warren, W.L.; Hetherington, D.L.; Timon, R.P.; Resnick, P.J.; Winokur, P.S.

    1994-12-31

    Defect centers generated in vacuum-ultraviolet irradiated chemical-mechanical polished oxides have been characterized using electron paramagnetic resonance and C-V analysis. Both oxide trap E{sub {gamma}} and interface trap P{sub b0} centers were detected in unpolished and polished oxides. In addition, another interface defect center known as the P{sub b1} center was only identified in the polished oxides, suggesting that the polishing process altered the SiO{sub 2}/Si interface.

  20. Slurry Supplying Method for Large Quartz Glass Substrate Polishing

    NASA Astrophysics Data System (ADS)

    Khajornrungruang, Panart; Kimura, Keiichi; Yui, Ryuji; Wada, Nagisa; Suzuki, Keisuke

    2011-05-01

    Chemical mechanical polishing (CMP) has been used in polishing a photomask substrate in flat-panel display (FPD) manufacture. Moreover, the quadrilateral geometry of quartz glass used as the photomask substrate has been enlarged. However, the slurry cannot flow throughout the glass surface evenly owing to the enlarged substrate covering the center of the platen in the polishing process. In this work, we verified the beneficial of spreading slurry into a non-inflow region by the reinforced suction of the slurry supplied to the polishing pad through a hole at center of the platen. A fluorescent agent was used instead of the slurry for flow visualization.

  1. Condensate polishers for brackish water-cooled PWRs

    SciTech Connect

    Sadler, M.A.; Darvill, M.R.; Bickerstaffe, J.A.; Chakravorti, R.; Siegwarth, D.P.

    1986-07-01

    The objectives of project RP 1571-5 ''Optimization of Pressurized Water Reactor Secondary Water Treatment: Task 4 Conceptual Design Options - Condensate Polishing'' were to provide detailed guidelines for the design of a condensate polishing system for retrofitting to a seawater cooled PWR. For this purpose a national 1100MW PWR with recirculating steam generators was defined. The polished water to be produced by this plant must be of such a quality so as to permit the advisory SGOG guidelines on impurity levels in Steam Generator water to be achieved. Target maximum impurity levels in the final polished water were proposed by the RP 1571 Project review Team and adopted for this study.

  2. Compatible taper and volume equations for young longleaf pine plantations in southwest Georgia

    Treesearch

    Lichun Jiang; John R. Brooks; Alexander Clark

    2010-01-01

    Inside and outside bark taper equations as well as compatible cubic foot volume equations were developed from felled tree data selected from young longleaf pine plantations that are part of an existing growth and yield study located in the Flint River drainage of southwest Georgia. A Max-Burkhart taper model was selected as the basic model form due to the accuracy...

  3. The mean aerodynamic chord and the aerodynamic center of a tapered wing

    NASA Technical Reports Server (NTRS)

    Diehl, Walter S

    1942-01-01

    A preliminary study of pitching-moment data on tapered wings indicated that excellent agreement with test data was obtained by locating the quarter-chord point of the average chord on the average quarter-chord point of the semispan. The study was therefore extended to include most of the available data on tapered-wing models tested by the NACA.

  4. 77 FR 12326 - Tapered Roller Bearings From China; Scheduling of a Full Five-Year Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-29

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Tapered Roller Bearings From China; Scheduling of a Full Five- Year Review AGENCY: United States... Act) to determine whether revocation of the antidumping duty order on tapered roller bearings from...

  5. 77 FR 16859 - Tapered Roller Bearings From China; Scheduling of a Full Five-Year Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-22

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Tapered Roller Bearings From China; Scheduling of a Full Five- Year Review AGENCY: United States...)) (the Act) to determine whether revocation of the antidumping duty order on tapered roller bearings from...

  6. Polarization-independent all-fiber isolator based on asymmetric fiber tapers.

    PubMed

    Fang, X

    1996-11-01

    Nonreciprocal intensity transmission in optical fibers can be realized by use of an asymmetric fiber taper. A few-mode fiber taper-based nonreciprocal component is designed, and its nonreciprocal transmission characteristics are demonstrated. This structure can be employed to build polarization-independent all-fiber isolators or fiber-optic sensors.

  7. Taper models for commercial tree species in the northeastern United States

    Treesearch

    James A. Westfall; Charles T. Scott

    2010-01-01

    A new taper model was developed based on the switching taper model of Valentine and Gregoire; the most substantial changes were reformulation to incorporate estimated join points and modification of a switching function. Random-effects parameters were included that account for within-tree correlations and allow for customized calibration to each individual tree. The...

  8. Development of a photogrammetric method of measuring tree taper outside bark

    Treesearch

    David R. Larsen

    2006-01-01

    A photogrammetric method is presented for measuring tree diameters outside bark using calibrated control ground-based digital photographs. The method was designed to rapidly collect tree taper information from subject trees for the development of tree taper equations. Software that is commercially available, but designed for a different purpose, can be readily adapted...

  9. Dynamic analysis of tapered laminated composite magnetorheological elastomer (MRE) sandwich plates

    NASA Astrophysics Data System (ADS)

    Babu, V. Ramesh; Vasudevan, R.

    2016-03-01

    In the present study, the dynamic performance of the sandwich plate with magneto rheological elastomer (MRE) as the core layer and tapered laminated composite plates as the face layers is investigated. Various MRE tapered laminated composite sandwich plate models are formulated by dropping-off the plies longitudinally in top and bottom composite layers to yield tapered plates as the face layers and uniform MRE layer as the core layer. The governing equations of motion of tapered composite MRE sandwich plates are derived using classical laminated plate theory and solved numerically. Further, silicon based MRE is being fabricated and tested to obtain the shear and loss moduli using MR rheometer. The efficacy of the finite element formulation is validated by carrying out experiments on the various prototypes of tapered composite silicon based MRE sandwich plates and comparing the results in terms of natural frequencies obtained at various magnetic fields with those obtained numerically and with available literature. Also, the effects of magnetic field, taper angle of the top and bottom layers, aspect ratio, ply orientations and various end conditions on the various dynamic properties of tapered laminated composite MRE sandwich plate are investigated. Further, the transverse vibration responses of three different tapered composite MRE based sandwich plates under harmonic force excitation are analyzed at various magnetic fields.

  10. Validation of Volume and Taper Equations For Loblolly Shortleaf and Slash Pine

    Treesearch

    Allan E. Tiarks; V. Clark Baldwin

    1999-01-01

    Inside-bark diameter measurements at 6.64 intervals of 137 loblolly, 52 shortleaf, and 64 slash pines were used to calculate the actual volume and taper of each species for comparison with volumes and tapers predicted from published equations. The loblolly pine were cut in Texas (TX) and Louisiana (LA) while the shortleaf was sampled only in TX. The slash pine were...

  11. Simple Expressions for the Design of Linear Tapers in Overmoded Corrugated Waveguides

    DOE PAGES

    Schaub, S. C.; Shapiro, M. A.; Temkin, R. J.

    2015-08-16

    In this paper, simple analytical formulae are presented for the design of linear tapers with very low mode conversion loss in overmoded corrugated waveguides. For tapers from waveguide radius a2 to a1, with a11a2/λ. Here, λ is the wavelength of radiation. The fractional loss of the HE 11 mode in an optimized taper is 0.0293(a2-a1)4/amore » $$2\\atop{1}$$1a$$2\\atop{2}$$. These formulae are accurate when a2≲2a1. Slightly more complex formulae, accurate for a2≤4a1, are also presented in this paper. The loss in an overmoded corrugated linear taper is less than 1 % when a2≤2.12a1 and less than 0.1 % when a2≤1.53a1. The present analytic results have been benchmarked against a rigorous mode matching code and have been found to be very accurate. The results for linear tapers are compared with the analogous expressions for parabolic tapers. Finally, parabolic tapers may provide lower loss, but linear tapers with moderate values of a2/a1 may be attractive because of their simplicity of fabrication.« less

  12. Tapering from Methadone or Buprenorphine during Pregnancy: Maternal and Neonatal Outcomes in Norway 1996-2009.

    PubMed

    Welle-Strand, Gabrielle K; Skurtveit, Svetlana; Tanum, Lars; Waal, Helge; Bakstad, Brittelise; Bjarkø, Lisa; Ravndal, Edle

    2015-01-01

    The tapering of methadone or buprenorphine during pregnancy is an understudied and controversial issue. The aim of this study was to determine to what extent women tapered their opioid medication dose during pregnancy and what the neonatal outcomes were for those who tapered compared to the women who did not. The study was a mixed prospective/retrospective national cohort study of 123 Norwegian women in opioid maintenance treatment (OMT) during pregnancy and their neonates. A standardized questionnaire was administered to the women and medical information that could be used for verification was collected from hospitals and municipalities. Two of the women came off the OMT-medication during pregnancy and another 15% tapered their OMT-medication dose more than 50%. The birth weights of methadone-exposed neonates of the women who tapered more than 50% were significantly higher than for the methadone-exposed neonates of the women tapering between 11 and 50%. No other significant differences were found. Pregnant women in OMT who taper their OMT-medication dose should be monitored closely. We need studies that document the maternal well-being and fetal safety of maternal tapering of the OMT-medication during pregnancy. © 2015 S. Karger AG, Basel.

  13. Using “Sub-cement” to simulate the long-term fatigue response of cemented femoral stems in a cadaver model: could a novel pre-clinical screening test have caught the Exeter matte problem?

    PubMed Central

    Race, Amos; Miller, Mark A.; Mann, Kenneth A.

    2010-01-01

    Previously, we formulated cement with degraded fatigue properties (sub-cement) to simulate long-term fatigue in short-term cadaver tests. The present study determined the efficacy of sub-cement in a `pre-clinical' test of a design change with known clinical consequences: the “polished” to “matte” transition of the Exeter stem (revision rates were twice as high for matte stems). Contemporary stems were bead-blasted to give Ra=1micron (matte finish). Matte and polished stems were compared in cadaver pairs under stair-climbing loads (3 pairs size-1, 3 pairs size-3). Stem micromotion was monitored during loading. Post-test, transverse sections were examined for cement damage. Cyclic retroversion decreased for polished stems but increased for matte stems (p<0.0001). Implant size had a substantial effect: retroversion of (larger) size-3 stems was half that of size-1 stems and polished size-3 stems subsided 2½ times more than the others. Cement damage measures were similar and open through-cracks occurred around both stems of two pairs. Stem retroversion within the mantle resulted in stem-cement gaps of 50–150microns. Combining information on cyclic motion, cracks, and gaps, we concluded that this test `predicted' higher revision rates for matte stems (it also implied that polished size-3 stems might be superior to size-1). PMID:20476506

  14. Incidence of apical crack initiation and propagation during the removal of root canal filling material with ProTaper and Mtwo rotary nickel-titanium retreatment instruments and hand files.

    PubMed

    Topçuoğlu, Hüseyin Sinan; Düzgün, Salih; Kesim, Bertan; Tuncay, Oznur

    2014-07-01

    The aim of this study was to determine the incidence of crack initiation and propagation in apical root dentin after retreatment procedures performed by using 2 rotary retreatment systems and hand files with additional instrumentation. Eighty extracted mandibular premolars with single canals were selected. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the control group, and no preparation was performed. The remaining 60 teeth were prepared to size 35 with rotary files and filled with gutta-percha and AH Plus sealer. Specimens were then divided into 3 groups (n = 20), and retreatment procedures were performed with the following devices and techniques: ProTaper Universal retreatment files, Mtwo retreatment files, and hand files. After retreatment, the additional instrumentation was performed by using size 40 ProTaper, Mtwo, and hand files. Digital images of the apical root surface were recorded before preparation, after instrumentation, after filling, after retreatment, and after additional instrumentation. The images were then inspected for the presence of any new apical cracks and propagation. Data were analyzed with the logistic regression and Fisher exact tests. All experimental groups caused crack initiation and propagation after use of retreatment instruments. The ProTaper and Mtwo retreatment groups caused greater crack initiation and propagation than the hand instrument group (P < .05) after retreatment. Additional instrumentation with ProTaper and Mtwo instruments after the use of retreatment instruments caused crack initiation and propagation, whereas hand files caused neither crack initiation nor propagation (P < .05). This study showed that retreatment procedures and additional instrumentation after the use of retreatment files may cause crack initiation and propagation in apical dentin. Copyright © 2014 American Association of Endodontists

  15. A Report of Successful Procedural, Clinical, and Angiographic Outcomes with a Tapered Stent of a Patient in Naturally Tapered Coronary Vessel

    PubMed Central

    Kumar, Yerra Shiv

    2017-01-01

    In cases involving stenosis or occlusions in major parts of a long vessel, natural tapering of coronary vessels may create dilemma in deciding the optimal stent size during percutaneous coronary intervention. In this regard, tapered stents have been developed recently. Herein, we present a case of 67-year-old male patient with triple vessel disease including two tandem lesions in naturally tapered Left Anterior Descending (LAD) artery. The patient received a 3.0–2.5x60 mm Sirolimus-eluting BioMime Morph stent (Meril life Sciences, Gujarat, India) in the mid-distal LAD lesion along with conventional stent implantations in other two lesions. The procedure was successful and good coronary flow was obtained after revascularization. The patient remained asymptomatic thereafter. At one year, angiographic follow-up revealed good flow and no restenosis in the LAD vessel. We are of opinion that using tapered stents with decremented diameter may offer the advantages of excellent adaptation to vessel size, vessel tapering, and good apposition in patients with long coronary lesions in tapered vessels. PMID:28273994

  16. Comparison of debris extruded apically and working time used by ProTaper Universal rotary and ProTaper retreatment system during gutta-percha removal

    PubMed Central

    UEZU, Mary Kinue Nakamune; BRITTO, Maria Leticia Borges; NABESHIMA, Cleber K.; PALLOTTA, Raul Capp

    2010-01-01

    Objective The aim of this study was to evaluate the in vitro action of ProTaper retreatment files and ProTaper Universal in the retreatment of mandibular premolars. Material and methods The amount of debris extruded apically was measured and the time to reach the working length and to complete the removal of gutta-percha was observed. Thirty teeth had their canals prepared using ProTaper Universal files and were obturated by the single cone technique. The teeth were then stored at 37ºC in a humid environment for 7 days. During the use of the rotary instruments for root canal filling removal, the apical portions of the teeth were attached to the open end of a resin tube to collect the apically extruded debris. Results ProTaper Universal files were significantly faster (p=0.0011) than the ProTaper retreatment files to perform gutta-percha removal, but no significant difference was found between the files regarding the time to reach the working length or the amount of apical extrusion. Conclusions ProTaper Universal rotary had better results for endodontic retreatment, and both techniques promote similar apical extrusion of debris. PMID:21308282

  17. Robotic Automation in Computer Controlled Polishing

    NASA Astrophysics Data System (ADS)

    Walker, D. D.; Yu, G.; Bibby, M.; Dunn, C.; Li, H.; Wu, Y.; Zheng, X.; Zhang, P.

    2016-02-01

    We first present a Case Study - the manufacture of 1.4 m prototype mirror-segments for the European Extremely Large Telescope, undertaken by the National Facility for Ultra Precision Surfaces, at the OpTIC facility operated by Glyndwr University. Scale-up to serial-manufacture demands delivery of a 1.4 m off-axis aspheric hexagonal segment with surface precision < 10 nm RMS every four days, compared with a typical year or more for an one-off part. This requires a radically-new approach to large optics fabrication, which will inevitably propagate into wider industrial optics. We report on how these ambitious requirements have stimulated an investigation into the synergy between robots and computer numerically controlled ('CNC') polishing machines for optical fabrication. The objective was not to assess which is superior. Rather, it was to understand for the first time their complementary properties, leading us to operate them together as a unit, integrated in hardware and software. Three key areas are reported. First is the novel use of robots to automate currently-manual operations on CNC polishing machines, to improve work-throughput, mitigate risk of damage to parts, and reduce dependence on highly-skilled staff. Second is the use of robots to pre-process surfaces prior to CNC polishing, to reduce total process time. The third draws the threads together, describing our vision of the automated manufacturing cell, where the operator interacts at cell rather than machine level. This promises to deliver a step-change in end-to-end manufacturing times and costs, compared with either platform used on its own or, indeed, the state-of-the-art used elsewhere.

  18. Comparison of canal transportation in simulated curved canals prepared with ProTaper Universal and ProTaper Gold systems

    PubMed Central

    Muniz, Brenda Leite; Pires, Frederico; Belladonna, Felipe Gonçalves; Neves, Aline Almeida; Souza, Erick Miranda; De-Deus, Gustavo

    2016-01-01

    Objectives The purpose of this study was to assess the ability of ProTaper Gold (PTG, Dentsply Maillefer) in maintaining the original profile of root canal anatomy. For that, ProTaper Universal (PTU, Dentsply Maillefer) was used as reference techniques for comparison. Materials and Methods Twenty simulated curved canals manufactured in clear resin blocks were randomly assigned to 2 groups (n = 10) according to the system used for canal instrumentation: PTU and PTG groups, upto F2 files (25/0.08). Color stereomicroscopic images from each block were taken exactly at the same position before and after instrumentation. All image processing and data analysis were performed with an open source program (FIJI). Evaluation of canal transportation was obtained for two independent canal regions: straight and curved levels. Student's t test was used with a cut-off for significance set at α = 5%. Results Instrumentation systems significantly influenced canal transportation (p < 0.0001). A significant interaction between instrumentation system and root canal level (p < 0.0001) was found. PTU and PTG systems produced similar canal transportation at the straight part, while PTG system resulted in lower canal transportation than PTU system at the curved part. Canal transportation was higher at the curved canal portion (p < 0.0001). Conclusions PTG system produced overall less canal transportation in the curved portion when compared to PTU system. PMID:26877984

  19. Theoretical span loading and moments of tapered wings produced by aileron deflection

    NASA Technical Reports Server (NTRS)

    Pearson, H A

    1937-01-01

    The effect of tapered ailerons on linearly tapered wings is theoretically determined. Four different aileron spans are considered for each of three wing aspect ratios and each of four wing taper ratios. The change in lift on one half of the wing, the rolling moment, the additional induced drag, and the yawing moment, due to aileron deflection, are represented by non dimensional coefficients. Similar coefficients are given for the damping and yawing moments, the additional drag, and the change in lift, due to rolling. It was found possible to effect a fairly close agreement between the theoretical and experimental rolling moments by introducing into the theoretical expression for the rolling moment an effective change in angle of attack obtained from an analysis of flap data. The theoretical curves show that the highly tapered wing with long ailerons has a lower ratio of yawing to rolling moment and a lower additional induced drag than wings with less taper.

  20. Miniature tapered photonic crystal fiber interferometer with enhanced sensitivity by acid microdroplets etching.

    PubMed

    Qiu, Sun-jie; Chen, Ye; Kou, Jun-long; Xu, Fei; Lu, Yan-qing

    2011-08-01

    We fabricate a miniature tapered photonic crystal fiber (PCF) interferometer with enhanced sensitivity by acid microdroplets etching. This method is very simple and cost effective, avoiding elongating the PCF, moving and refixing the device during etching, and measuring. The refractive index sensing properties with different PCF diameters are investigated both theoretically and experimentally. The tapering velocity can be controlled by the microdroplet size and position. The sensitivity greatly increases (five times, 750 nm/RIU) and the size decreases after slightly tapering the PCF. The device keeps low temperature dependence before and after tapering. More uniformly and thinly tapered PCFs can be realized with higher sensitivity (∼100 times) by optimizing the etching process.