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Purpose: This study aimed to compare HyFlex electrical discharge machining Glide Path, ProGlider, TruNatomy Glider, and WaveOne Gold Glider in terms of topographic changes after instrumentation. Methods: Simulated canals with 40° curvature were used to analyze the surface behavior of four brands of micro-glide path files (n = 36 in total, n = 3/subgroup). The files were used in single or three simulated canals for micro-glide path preparation. Surface topographies were evaluated using atomic force microscopy. The data were analyzed with Shapiro-Wilk and two-way robust analysis of variance tests. Results: RMS median values did not differ according to the file groups (p = 0.448) and use (p = 0.055). There was a significant difference between the intact WaveOne Gold Glider group and the use of 3 times (p = 0.002). Conclusion: The tested files exhibited acceptable surface behavior considering single use but in multirooted teeth. However, it should be considered that more surface distortion occurs on the surface of heat-treated files when used for multiple roots, especially curved ones. [ABSTRACT FROM AUTHOR]

Copyright of Meandros Medical & Dental Journal is the property of Galenos Yayinevi Tic. LTD. STI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: To compare the effect of glide path established by size 20/0.02 taper hand K-file and size 20/0.04 taper rotary file, on the amount of debris extruded apically during root canal instrumentation by rotary ProTaper Universal (S1-F2) and reciprocating WaveOne (Primary) file systems. Materials and methods: Eighty mandibular molars with curved mesial roots and two separate canals were selected and randomly divided into two groups (n = 40) for glide path preparation using either size 20/0.02 taper hand K-files and size 20/0.04 taper rotary files. These groups were further divided into two (n = 20) for root canal instrumentation by ProTaper Universal and WaveOne files; Group 1: 20/0.02 + ProTaper, Group 2: 20/0.02 + WaveOne, Group 3: 20/0.04 + ProTaper, and Group 4: 20/0.04 + WaveOne. The debris extruded during instrumentation was collected in pre-weighed Eppendorf tubes and stored in an incubator at 70°C for 5 days. Tubes containing the dry, extruded debris were then weighed. One-way analysis of variance was applied to the weights obtained followed by Tukey's post hoc test for multiple comparison. Results: All the groups resulted in debris extrusion. Establishing a glide path with size 20/0.04 taper rotary files, resulted in less debris extrusion, compared to a glide path prepared by size 20/0.02 taper hand K-files (P < 0.001). Conclusion: Creating a glide path with size 20/0.04 rotary file, reduced the debris extrusion in curved root canals during instrumentation by ProTaper Universal and WaveOne. [ABSTRACT FROM AUTHOR]

The 'glide path' in non-surgical root canal treatment refers to a smooth radicular tunnel from the root canal orifice to its terminus. Its establishment is aimed at creating sufficient space to facilitate the subsequent and safer use of engine-driven nickel titanium (NiTi) shaping files. Glide paths were originally prepared using stainless steel hand files to, at least, a loose International Organisation for Standardisation (ISO) size 10 or larger. However, the advent of engine-driven NiTi instrumentation has led to the availability of many enginedriven NiTi glide path files. The aims of this review were to assess the effects of engine-driven and manual glide path preparation (GPP) on root canal shaping procedures and outcomes. An online search of the PubMed, Embase, Scopus and ScienceDirect databases was conducted and 32 studies were identified. The published literature suggests the use of engine-driven glide path files to be beneficial in maintaining the original root canal anatomy, reducing preparation time, decreasing apical extrusion of debris and causing less postoperative pain. However, there was no difference between engine-driven and manual GPP with regards to the physical strain exerted on the shaping files. Future research focused on clinical outcomes is needed to help ascertain the clinical benefits for patients. [ABSTRACT FROM AUTHOR]

Aim: To evaluate in a laboratory setting the performance of two reciprocating glide path systems, WaveOne Gold Glider (WO) and R‐Pilot (RP), to create a glide path in mesial root canals of mandibular molars and to assess the torsional resistance of instruments after performing the glide path. Methodology: A total of 60 mesial root canals of extracted human mandibular molars were divided into two groups (n = 30) according to the glide path system to be used. The data from the volume of each canal, acquired by microcomputed tomography (micro‐CT), were validated statistically for the anatomical pairing of the groups. Preparation time, frequency in gaining apical patency, plastic deformation rate of instruments, and canal transportation and centring ability were recorded and compared statistically. The torsional fatigue of the instruments after use was also evaluated. Data were analysed using Fisher's exact test and Mann–Whitney U‐test with a 5% significance level. Results: No significant differences were found between groups regarding the time required to perform the glide path, the frequency distributions of the canals classified as patent and the instruments with plastic deformation after use (P > 0.05). No significant differences were found between groups regarding the degree of canal transportation and centring ability at the cervical, middle and apical thirds (P > 0.05). The RP groups had significantly greater maximum torsional strength values compared with the WO groups (P < 0.05). The used WO group had greater angular deflection to fracture when compared to the new WO group (P < 0.05). A significant difference was also found in the percentage of loss of angular deflection in a comparison of the WO group with the RP group (P < 0.05). Conclusions: The WO and RP instruments performed the same in terms of preparation time, plastic deformation, gaining apical patency, degree of canal transportation and centring ability. The RP instruments had greater torsional strength, less angular deflection and lower percentage of loss in angular deflection than the WO. The used WO group had the greatest angular deflection values. [ABSTRACT FROM AUTHOR]

Objective. To evaluate the clinical application effect of two nickel-titanium engine driven systems on moderate curved root canals. Methods. Ninety mesial root canals with moderate curvature of extracted human first mandibular permanent molar were randomly divided into three groups: M3 PRO Group, MTwo group and K group. The glide path was firstly preparedusing 10/04 file in M3 PRO group and MTwo group and 10 file in K group respectively. Then the preparation of root canals up to 25 was performed according to the instruction manual in each different group using standardized technique. All data including time required in glide path preparation, shaping preparation, total root canals preparation and changes of working length in root canal were recorded and analyzed statisticallyusing Analysis of Variance (ANOVA) and LSD-t tests (PResults. Root canal glide path preparation time: MTwo group showed significantly less preparation time while M3 PRO group exhibited significantly the longest preparation time. There was significant difference between MTwo group and M3 PRO group (P0.001). Root canal shaping preparation time: M3 PRO group showed significantly less preparation time while K group exhibited significantly the longest preparation time. Both MTwo group and M3 PRO group showed significantly less preparation time than K group (P0.004, P0.001), but there was no significant difference between MTwo group and M3 PRO group (P0.573). Total root canal preparation time: MTwo group showed the shortest time while K group exhibited the longest time. There were significant differences between MTwo group, M3 PRO group and K group (P0.004, P0.033), but no significant difference between MTwo group and M3 PRO group (P0.451). Changes of root canal working length: There were significant differences among the three groups (P0.037, P0.037, P0.000). M3 PRO group showed a minimal change while K group exhibited significant changes. Conclusion. MTwo nickel-titanium engine driven system with 10/04 file preform a high efficiency in glide path preparation, whilst M3 PRO nickel-titanium engine driven system show less changes in working length. Under the circumstancesthe total time required for root canal preparation is not significant, M3 PRO nickel-titanium engine driven system is more suifor root canal preparation in moderate curved root canals. [ABSTRACT FROM AUTHOR]

This paper focuses on the application of H∞ preview control in automatic carrier landing system(ACLS)for carrier-based aircraft. Due to the mutual movement between aircraft and carrier,the landing process becomes considerably more challenging compared to a conventional runway landing. ACLS systems mitigate this by predicting deck motion and generating ideal glide slope path for tracking. Although,this predicted glide slope information is available in advance,conventional control structures are still unable to use this future information. H∞ preview control has the ability to utilize this future information for improving tracking response and disturbance rejection. The process of incorporating preview information into ACLS framework and synthesizing the H∞ preview controller is presented.The methodology is verified using the example of F/A-18 automatic carrier landing problem and results are presented [ABSTRACT FROM AUTHOR]

Aim: To compare the cyclic fatigue resistance of four reciprocating single‐file systems within artificial stainless‐steel canals at two temperatures using different kinematics. Methodology: A total of 240 instruments, Reciproc Blue, Reciproc, WaveOne Gold and WaveOne, (60 of each), were tested at room and intracanal temperature using both a static and a dynamic model (n = 15) in a stainless‐steel artificial canal with an inner diameter of 1.5 mm, 60° angle of curvature and 5 mm radius of curvature until fracture occurred. The time to fracture was measured in seconds using a digital chronometer, and data were analysed using one‐way analysis of variance and Bonferroni tests. Results: WaveOne instruments had significantly less fatigue resistance compared to that of other systems in all conditions (P < 0.05). Comparison of the results from the static and dynamic models at both temperatures revealed that fatigue resistance was significantly increased in the dynamic model for all the instrument systems (P < 0.05). Temperature did not influence the cyclic fatigue resistance results (P > 0.05). There were no significant differences in the mean length of the fractured fragments of the various instruments tested (P > 0.05). Conclusion: WaveOne files had a shorter cyclic fatigue life. The dynamic axial movement extended the cyclic fatigue life, but it did not have any influence on the comparison among the instruments tested in respect of the static test. Temperature did not significantly affect the cyclic fatigue of these nickel–titanium files. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the torsional properties of the NiTi glide path reciprocating instruments R‐Pilot (VDW, Munich, Germany) and WaveOne Gold Glider (Dentsply Sirona, Ballaigues, Switzerland). Methodology: Ten R‐Pilot (size 12.5,.04 taper) and 10 WaveOne Gold Glider (size 15,.02v taper) instruments were used. The torque and angle of rotation at failure of new instruments (n = 10) were measured according to ISO 3630‐1. Three millimetres of each instrument tip was clamped to a small load cell by a lever arm linked to the torsion axis. The fracture surface of all fragments was examined with a scanning electron microscope. Data were analysed using the Student t‐test at a significance level of P < 0.05. Results: The maximum torsional strength of the R‐Pilot instruments was greater than the WaveOne Gold Glider (P < 0.05). In contrast, WaveOne Gold Glider instruments had significantly higher angular rotation to fracture than R‐Pilot instruments (P < 0.05). The scanning electron microscopy of the fracture surfaces revealed similar and typical features of torsional failure (ductile type) for both brands. The torsional failure displayed two zones: the first with microvoids in the centre of the instruments (core) and the second one represented by plastic deformation around the microvoids; this configuration occurred because of the shear stresses originated during the twisting. Conclusions: R‐Pilot instruments had a lower angle of rotation to fracture but a higher torque to failure than WaveOne Gold Glider instruments. [ABSTRACT FROM AUTHOR]

Aim: To compare the incidence, intensity and prediction of postoperative pain after glide path preparation with manual, continuous rotary and a novel reciprocating glide path instrument. Methodology: The study included 240 patients, who were treated by four specialists according to a planned treatment protocol. Following access cavity preparation and prior to glide path preparation, the subjects were randomly assigned to one of the three groups according to the glide path instrument by choosing a sealed envelope containing the group name: R‐Pilot (VDW, Munich, Germany), ProGlider (Dentsply Sirona, Ballaigues, Switzerland) and stainless steel K‐files (Dentsply Sirona; n = 80). Following glide path preparation, the teeth underwent standardized single visit root canal treatment procedures. The root canals were chemomechanically prepared using the ProTaper Next rotary system (Dentsply Sirona) under copious irrigation with 5.25% NaOCl. Final irrigation was performed with 17% EDTA and distilled water. Root fillings were placed using an epoxy resin sealer and gutta‐percha with a cold lateral compaction technique. After coronal restorations were placed, the patients were discharged with a questionnaire about the incidence and intensity of pain at 6, 12, 18, 24, 48 and 72 h postoperatively. The data were analysed using chi‐square, anova and Tukey tests and logistic regression analysis. Results: The presence of preoperative pain (OR ranged between 3.5 and 14.3) and the glide path preparation techniques (OR between 2.2 and 4.1) were associated with significant effects on the incidence of postoperative pain when comparing manual versus engine‐driven glide path preparation (P < 0.05). Patients in the R‐Pilot (Mean VAS ranged between 1.57–0.21) and ProGlider (1.97–0.28) groups reported significantly less postoperative pain scores than those in the manual group (2.82–1.32; P < 0.05). There was no significant difference between R‐Pilot and ProGlider groups regarding the postoperative pain scores (P > 0.05). Conclusion: Preparation of glide paths with rotating or reciprocating NiTi instruments was associated with less postoperative pain levels and incidence compared to manual glide path preparation with no significant difference between rotating and reciprocating instruments. Preoperative pain was the most significant predictor for the occurrence of postoperative pain. [ABSTRACT FROM AUTHOR]

Aim: To compare (i) canal‐centring ability and transportation of K‐files, ProGlider and One‐G files after glide path preparation in curved root canals; (ii) changes in canal volume after glide path preparation, using micro‐computed tomography. Methodology: A total of 135 mesiobuccal root canals of maxillary molars were randomly divided into three glide path groups: (i) pre‐curved sizes 10‐15‐20 K‐files (n = 45); (ii) size 10 K‐file followed by One‐G (n = 45); and (iii) size 10 K‐file followed by ProGlider (n = 45). Micro‐CT was used to scan teeth before and after glide path preparation; the isotropic voxel size of the micro‐CT scans was 22 μm. Centring ratio values and canal transportation values were compared between the three glide path preparation groups at the apical, midroot and coronal levels. Changes in canal volume were compared for all glide path groups. The results were analysed statistically using a one‐way anova and Kruskal–Wallis H tests. Results: One‐G and ProGlider displayed significantly greater mean centring ratio values than K‐files at all levels examined (P < 0.05). Apical canal transportation values after glide path preparation were significantly higher for the K‐files (P < 0.05). At the midroot and coronal levels, canal transportation results were statistically similar for all glide path groups (P > 0.05). Changes in canal volume were statistically similar for the three glide path groups (P > 0.05). Conclusion: One‐G and ProGlider were significantly more centred at the apical, midroot and coronal levels than K‐files. Apical canal transportation ratio values after glide path enlargement were significantly higher for K‐files than for One‐G and ProGlider. All groups resulted in similar canal volume changes. [ABSTRACT FROM AUTHOR]

Objective: The aim of the present study was to compare the cyclic fatigue resistance of R-Pilot (VDW; Munich, Germany) with ProGlider (Denstply Sirona; Ballaigues, Switzerland) and WaveOne Gold Glider (Denstply Sirona; Ballaigues, Switzerland) glide path instruments.Materials and methods: R-Pilot, ProGlider, and WaveOne Gold Glider instruments were collected (n = 15) and tested in a dynamic cyclic fatigue test device, which has an artificial canal with 60° angle of curvature and a 5-mm radius of curvature. All instruments were operated until fracture occurred, and both time to fracture (TF) and the lengths of the fractured fragments were recorded. Mean and standard deviations of TF and fragment length were calculated for each reciprocating system. TF data and fractured fragment length data were subjected to one-way ANOVA and post-hoc Tukey tests (P < 0.05). Also a Weibull analysis was performed on TF data.Results: The cyclic fatigue resistance values of the WaveOne Gold Glider and R-Pilot were significantly higher than those of the ProGlider (P < 0.05), with no significant difference between them (P > 0.05). Weibull analysis revealed that WaveOne Gold Glider showed the highest predicted TF value for 99% survival rate, which was followed by R-Pilot and ProGlider. Regarding the length of the fractured tips, there were no significant differences among the instruments (P > 0.05).Conclusions: The reciprocating WaveOne Gold Glider and R-Pilot instruments had significantly higher cyclic fatigue resistance than rotary ProGlider instruments.Clinical relevance: This study reported that novel reciprocating glide path instruments exhibited higher cyclic fatigue resistance than rotating glide path instrument. [ABSTRACT FROM AUTHOR]

Abstract For the carrier-based unmanned aerial vehicles (UAVs), one of the important problems is the design of an automatic carrier landing system (ACLS) that would enable autonomous landing of the UAVs on a moving aircraft carrier. However, the safe autolanding on a moving aircraft is a complex task, mainly because of the deck motion and airwake disturbances, and dimension limitation. In this paper, an innovative ACLS system for carrier-based UAVs is developed, which is composed of the flight deck motion prediction, reference glide slope generation and integrated guidance and control (IGC) modules. The particle filtering method is used to online predict the magnitudes and frequencies of the deck motion, which are used to correct the reference glide slope to achieve minimum dispersion around the ideal touchdown point. An optimal preview control (OPC) scheme is presented for the IGC subsystem design, which fuses the preview information of the reference glide slope, equality constraint of UAV dynamics and performance index function, and predicted information of the carrier deck motion. Simulation results of a nonlinear UAV model show the effectiveness of the ACLS system in carrier autolanding under the deck motion and airwake disturbances. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To compare the cyclic fatigue resistance and bending properties of R‐Pilot and WaveOne Gold (WOG) Glider files, at intracanal temperature (35°C). Methodology: Forty R‐Pilot and 40 WOG Glider files were subjected to a cyclic fatigue resistance test (n = 20), calculating the time to fracture (TTF) in an artificial stainless steel canal. The length of the fractured file tips (FL) was also measured. The fracture surface of fragments was examined with a scanning electron microscope, and the cross‐sectional area of the fractured surfaces was measured. Flexibility of the tested files (n = 20) was determined using 45° bending test. Data were analysed statistically using the Mann–Whitney U‐test at 5% significance level. Results: Time to fracture was significantly higher in the R‐Pilot group compared to the WOG Glider (P < 0.05). There was no significant difference between groups for fracture length. The bending resistance of R‐Pilot files was significantly greater than WOG Glider files (P < 0.05). Conclusions: A significant greater cyclic fatigue resistance was observed for R‐Pilot files compared to WOG Glider instruments, although the bending resistance of WOG Glider files was lower. [ABSTRACT FROM AUTHOR]

Introduction The aim of this study was to compare centering ability and transportation values of the Primary WaveOne Gold (PWOG; Dentsply Sirona, Ballaigues, Switzerland) instrument with or without different glide path techniques. Centering ability and transportation were also compared between the 3 different glide path preparation groups. Methods The mesiobuccal canals of 60 extracted human mandibular molars (curvature angles between 25° and 35° and radii ≤10 mm) were selected and randomly divided into 4 groups with 15 canals each. Canals were negotiated to patency with a #8 K-file. Canal preparations were performed by a single operator using precurved #10, 15, and 20 stainless steel manual K-files (group KF); a #10 stainless steel manual K-file followed by PathFiles #1–3 (Dentsply Sirona) (group PF); a #10 stainless steel manual K-file followed by the WaveOne Gold Glider (Dentsply Sirona) (group WOGG); and no further glide path preparation (group NG). Micro–computed tomographic imaging was used to scan teeth before and after glide path preparation. The final canal preparation was performed with PWOG; after which, all 60 specimens were scanned again using micro–computed tomographic imaging. Canal transportation and centering ratio values were determined over levels 3 mm, 5 mm, and 7 mm from the root apex after glide path preparation and again after final preparation with PWOG. One-way analysis of variance was used to statistically compare groups. The significance level was set at P < .05. Results No statistically significant difference in the mean centering ratios was found after glide path preparation when the KF, PF, and WOGG groups were compared ( P > .05). The mean combined transportation values after glide path preparation were statistically significantly higher in the KF group compared with the PF and WOGG groups ( P > .05). There was no statistically significant difference in the mean combined centering ratios or transportation values of the NG and 3 glide path groups in combination with PWOG over the 3 levels ( P > .05). Conclusion KF group showed the highest mean transportation values during glide path preparation. However, the PWOG instrument's performance regarding centering ability and transportation was not influenced by the different glide path/no glide path preparation groups. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To compare the cyclic fatigue resistance of the One G, ProGlider, HyFlex EDM and R‐Pilot glide path NiTi files at body temperature. Methodology: Twenty One G (size 14, .03 taper), 20 ProGlider (size 16, .02 taper), 20 HyFlex EDM (size 10, .05 taper) and 20 R‐Pilot (size 12.5, .04 taper) instruments were operated in rotation at 300 rpm (One G, ProGlider and HyFlex) or in reciprocation (R‐Pilot) at 35 °C in artificial canals that were manufactured by reproducing the size and taper of the instrument until fracture occurred. The time to fracture was recorded in seconds using a digital chronometer, and the length of the fractured fragments was registered. Mean data were analysed statistically using the Kruskal–Wallis test and post hoc Tukey tests via SPSS 21.0 software. The statistical significance level was set at 5%. Results: The cyclic fatigue resistance of the R‐Pilot files was significantly greater than the other instruments, and the One G was significantly lower (P < 0.05). There was no difference between the HyFlex EDM and the ProGlider (P > 0.05). No significant difference (P > 0.05) was evident in the mean length of the fractured fragments of the various instruments. Conclusions: The cyclic fatigue resistance of the R‐Pilot reciprocating glide path file was significantly greater than that of the rotary HyFlex EDM, ProGlider and One G glide path files. [ABSTRACT FROM AUTHOR]

Copyright of Electronics & Control Systems is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Aim: To compare the cyclic fatigue resistance (CFR) of PathFile, ProGlider and ScoutRaCe nickel‐titanium (NiTi) rotary instruments used in an S‐shaped artificial canal. Methodology: A total of 90 instruments were tested in an S‐shaped artificial canal (n = 30 for each group: PathFile (size 16, 2% constant taper), ProGlider (size 16, variable taper between 2% and 8% along the shaft) and ScoutRaCe (size 15, 2% constant taper). All files were rotated until fracture. The number of cycles to failure was counted to determine CFR. The length of each fractured fragment was measured in millimetres. The CFR was analysed statistically with the Kruskal–Wallis test. The fragment length was analysed using one‐way analysis of variance and Tukey's post hoc tests. Results: The ProGlider instruments were associated with significantly greater CFR than the PathFile and ScoutRaCe files in the apical curvature (P < 0.05). There was no significant difference between the CFR of the PathFile and ScoutRaCe files in the apical curvature (P > 0.05). ProGlider, PathFile and ScoutRaCe instruments exhibited similar CFR in the coronal curvature (P > 0.05). Conclusions: The ProGlider files had greater cyclic fatigue resistance than the PathFile and ScoutRaCe files in the apical curvature of an artificial S‐shaped canal. [ABSTRACT FROM AUTHOR]

Introduction This study compared the effects of pitch length on the torsional resistance and cyclic fatigue resistance of glide path preparation instruments. Methods G-File (G1 and G2; Micro-Mega, Besançon, France) and new generation G-File (NG1 and NG2, Micro-Mega) instruments were compared to evaluate the effects of the shorter pitch of the latter (25% shorter than G-File). G1 and NG1 have a #12 tip size, whereas G2 and NG2 have a #17 tip size. All the files have the same taper of 3%. For comparing the torsional resistances ( n = 15), the file was fixed at 4 mm from the tip, and the clockwise rotation at a constant rotational speed of 2 rpm was adjusted until the file fractured. The maximum torsional load and distortion angle at fracture were recorded. For comparing the cyclic fatigue resistances ( n = 15), the files were freely rotated in a simulated canal (radius, 3 mm; curvature, 90°) at a speed of 300 rpm in a dynamic mode. When the file fractured, the time elapsed was recorded using a chronometer. The number of cycles to failure was calculated by multiplying the total time to failure by the rotation rate. Fractured fragments were examined under the scanning electron microscope. Results The NG2 instruments had significantly higher fatigue resistance and torsional strength than the G2 instruments ( P < .05) and showed approximately the same fatigue resistance as the G1. Scanning electron microscopic examinations revealed the typical appearances of 2 failure modes. Conclusions A shorter pitch design increased cyclic fatigue resistance and torsional strength of the glide path instruments. [ABSTRACT FROM AUTHOR]

Background. The present study aimed to compare the shaping ability of Reciproc Blue instruments with or without the creation of a glide path in simulated S-shaped root canals. Methods. Root canals of thirty #15.02 clear resin S-shaped blocks were dyed using ink and photographed. Then the blocks were randomly divided into 2 groups: group A: Reciproc Blue with glide path created with ProGlider and group B: Reciproc Blue with no glide path preparation (n=15). The blocks were also photographed after preparation. The pre- and post-preparation images were superimposed and evaluated at 9 different measurement points according to the 3 zones, as coronal straight, first curvature, and apical curvature zones. The data were evaluated with independent t-test or Kruskal-Wallis tests with 5% significance interval. Results. Group B removed greater amount of material from the inner aspect of simulated canal at the first curvature and apical curvature zones and from the outer aspect of the canal at apical curvature zone (P<0.05). Both groups exhibited transportation and the transportation width in group B was significantly greater in the levels of apical curvature zone (P<0.05). Conclusion. Glide path preparation using ProGlider rotary instrument improved the shaping ability of Reciproc Blue R25 instrument by leading to less transportation and maintaining centering ability. [ABSTRACT FROM AUTHOR]

Purpose: The paper is dedicated to improving of civil aviation flight safety question by the way of new method of aircraft landing by curvilinear glide paths within the boundary trajectories. Proposed method ordered for improving of safety level, sustainability and cost effectiveness of the aircraft landing with own individual, optimal vertical descending profile from flight level to the runway threshold. Methods: Landing method, based on generation (calculation and construction) of virtual curvilinear glide paths of landing within the boundary trajectories with taking into account of "fully controllable state areas" of aircraft has been proposed. Results: New aircraft landing method that has large profit in the reducing of the level of noises, fuel consumption and harmful emissions. Discussion: The essence of the method consists in using of fully controllable state areas that are constructed taking into account on linearity in aircraft flight characteristics, probable changes into environmental state, criterion of landing implementation optimality, all functional and aerodynamic aircraft capabilities for virtual curvilinear glide path construction, meant by some aircraft traffic trajectory for time and distance reducing, that are necessary for stage from start of descending from flight level to runway threshold. [ABSTRACT FROM AUTHOR]

Copyright of Electronics & Control Systems is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction The purpose of this study was to compare the cyclic fatigue resistance of used and new ProGlider (Dentsply Maillefer, Ballaigues, Switzerland) and PathFile (Dentsply Maillefer) rotary glide path files. Methods Forty ProGlider and 40 PathFile #2 instruments were used in the present study. In group 1, 20 PathFile #2 files and, in group 2, 20 ProGlider files were used to prepare a total of 40 J-shaped transparent acrylic blocks. In group 3 (control group), 20 new PathFile files and, in group 4 (control group), 20 new ProGlider files were included. Cyclic fatigue testing of instruments was performed in a stainless steel artificial canal with a 5-mm radius of curvature and a 60° angle of curvature. All 80 instruments were rotated until fracture, and the number of cycles to failure (NCF) was recorded. Data were analyzed using 1-way analysis of variance to determine any statistical difference; the significance was determined at the 95% confidence level. Results The used glide path files’ NCF was lower than the new ones; however, this difference was not statistically significant ( P > .05). The cyclic fatigue resistance of the used and new PathFile #2 files was statistically significantly higher than that of the ProGlider files ( P < .05). Conclusions Within the limitations of the present study, the used glide path files' NCF was lower than the new ones; however, this difference was not statistically significant. [ABSTRACT FROM AUTHOR]

Introduction The purpose of this study was to assess the ex vivo torsional performance of a novel rotary system in small root canals after 2 different glide path preparations. Methods Each independent canal of 8 mesial roots of mandibular molars was randomly assigned to achieve a reproducible glide path with a new set of either PathFile #1 (Dentsply Maillefer, Ballaigues, Switzerland) and #2 or ProGlider (Dentsply Maillefer) after negotiation with a 10 K-file. After glide path preparation, root canals in both groups were shaped with the same sequence of ProTaper Gold (Dentsply Tulsa Dental Specialties, Tulsa, OK) following the directions for use recommended by the manufacturer. A total of 16 new sets of each instrument of the ProTaper Gold (PTG) system were used. The tests were run in a standardized fashion in a torque-testing platform. Peak torque (Ncm) and force (N) were registered during the shaping procedure and compared with Student t tests after normal distribution of data was confirmed. Results No significant differences were found for any of the instruments in peak torque or force after the 2 different glide path preparations ( P > .05). Data presented in this study also serve as a basis for the recommended torque for the use of PTG instruments. Conclusions Under the conditions of this study, differences in the torsional performance of PTG rotary instruments after 2 different glide path preparations could not be shown. The different geometry of glide path rotary systems seemed to have no effect on peak torque and force induced by PTG rotary instruments when shaping small root canals in extracted teeth. [ABSTRACT FROM AUTHOR]

Objectives: To compare the relative axis modification and canal concentricity after glide path preparation with 20/0.02 hand K-file (NITIFLEX®) and 20/0.04 rotary file (HyFlex™ CM) with subsequent instrumentation with 1.5 mm self-adjusting file (SAF). Materials and Methods: One hundred and twenty ISO 15, 0.02 taper, Endo Training Blocks (Dentsply Maillefer, Ballaigues, Switzerland) were acquired and randomly divided into following two groups (n = 60): group 1, establishing glide path till 20/0.02 hand K-file (NITIFLEX®) followed by instrumentation with 1.5 mm SAF; and Group 2, establishing glide path till 20/0.04 rotary file (HyFlex™ CM) followed by instrumentation with 1.5 mm SAF. Pre- and post-instrumentation digital images were processed with MATLAB R 2013 software to identify the central axis, and then superimposed using digital imaging software (Picasa 3.0 software, Google Inc., California, USA) taking five landmarks as reference points. Student's t-test for pairwise comparisons was applied with the level of significance set at 0.05. Results: Training blocks instrumented with 20/0.04 rotary file and SAF were associated less deviation in canal axis (at all the five marked points), representing better canal concentricity compared to those, in which glide path was established by 20/0.02 hand K-files followed by SAF instrumentation. Conclusion: Canal geometry is better maintained after SAF instrumentation with a prior glide path established with 20/0.04 rotary file. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to test the effect of new protocol of glide path preparation by 20/0.04 rotary file on apical extrusion of debris when instrumenting fine curved mesial canals in mandibular molars with Self-adjusting File (SAF) and compare it to a glide path prepared by 20/0.02 hand K-file and rotary OneShape (OS) and reciprocating WaveOne (WO) file instrumentation. Materials and Methods: Sixty mandibular molars with curved mesial roots were selected and randomly divided into three groups (n = 20) for instrumentation. In two groups, glide path was prepared using 20/0.02 K-file for instrumentation by OS (size 25/0.06 taper) and WO (size 25/0.08 taper) files; in the remaining group, 20/0.04 rotary file was used for glide path preparation and instrumented by SAF (1.5 mm). The debris extruded during instrumentation was collected in preweighed Eppendorf tubes and stored in an incubator at 70°C for 5 days. Tubes containing the dry extruded debris were then weighed. One-way analysis of variance (ANOVA) was applied to the weights obtained, followed by Tukey's post hoc test for multiple comparison. Results: The mean debris (g) extruded apically was 0.000651 ± 0.000291, 0.000823 ± 0.000319, and 0.000473 ± 0.000238 for Group 1 (20/0.02 + OS), Group 2 (20/0.02 + WO), and Group 3 (20/0.04 + SAF), respectively. The groups exhibited a significant difference (P < 0.01; ANOVA). Group 3 resulted in least debris extrusion compared to Groups 1 and 2 (P < 0.01; Tukey's post hoc test). Conclusion: Glide path prepared to size 20/0.04 and SAF 1.5 mm instrumentation produce less debris in curved mesial canals of mandibular molars, compared to glide path established by 20/0.02 and instrumentation by OS and WO files. [ABSTRACT FROM AUTHOR]

The Ulleung Basin, East (Japan) Sea, is well-known for the occurrence of submarine slope failures along its entire margins and associated mass-transport deposits (MTDs). Previous studies postulated that gas hydrates which broadly exist in the basin could be related with the failure process. In this study, we identified various features of slope failures on the margins, such as landslide scars, slide/slump bodies, glide planes and MTDs, from a regional multi-channel seismic dataset. Seismic indicators of gas hydrates and associated gas/fluid flow, such as the bottom-simulating reflector (BSR), seismic chimneys, pockmarks, and reflection anomalies, were re-compiled. The gas hydrate occurrence zone (GHOZ) within the slope sediments was defined from the BSR distribution. The BSR is more pronounced along the southwestern slope. Its minimal depth is about 100 m below seafloor (mbsf) at about 300 m below sea-level (mbsl). Gas/fluid flow and seepage structures were present on the seismic data as columnar acoustic-blanking zones varying in width and height from tens to hundreds of meters. They were classified into: (a) buried seismic chimneys (BSC), (b) chimneys with a mound (SCM), and (c) chimneys with a depression/pockmark (SCD) on the seafloor. Reflection anomalies, i.e., enhanced reflections below the BSR and hyperbolic reflections which could indicate the presence of gas, together with pockmarks which are not associated with seismic chimneys, and SCDs are predominant in the western-southwestern margin, while the BSR, BSCs and SCMs are widely distributed in the southern and southwestern margins. Calculation of the present-day gas-hydrate stability zone (GHSZ) shows that the base of the GHSZ (BGHSZ) pinches out at water depths ranging between 180 and 260 mbsl. The occurrence of the uppermost landslide scars which is below about 190 mbsl is close to the range of the GHSZ pinch-out. The depths of the BSR are typically greater than the depths of the BGHSZ on the basin margins which may imply that the GHOZ is not stable. Close correlation between the spatial distribution of landslides, seismic features of free gas, gas/fluid flow and expulsion and the GHSZ may suggest that excess pore-pressure caused by gas hydrate dissociation could have had a role in slope failures. [ABSTRACT FROM AUTHOR]

An autonomous entry guidance law is developed based on 3-D analytical glide formulas, where the downrange formula is used to plan the longitudinal reference profile in order to meet the downrange and final energy requirements, and the crossrange formula is used to regulate the bank reversals in order to eliminate the crossrange error. As the analytical glide formulas ignore the effects of the Earth׳s rotation, a series of strategies is proposed for compensating these effects, which provides the guidance with the capability of steering the hypersonic glide vehicle with high Lift to Drag ratio ( L / D ) to any place of the world accurately. The compensation strategies can be summarized into two parts: (1) the reference profiles are properly adjusted by roughly evaluating the effects of the Earth׳s rotation on the aerodynamic profiles over the whole flight, which can compensate most of the effects; (2) the current effects are accurately evaluated and then the guidance commands are slightly modulated for compensating the remaining effects. Due to careful design, the strategies will not result in drastic changes in the Angle of Attack (AOA) and can keep the bank angle almost constant during most of flight. [ABSTRACT FROM AUTHOR]

Hydraulic units are often linked to ecological habitat through geomorphic structure, and a better understanding of the turbulent characteristics of the units is needed. Our work examined the near-bed turbulent structure of runs and glides in a restored river and investigated the physical characteristics that influenced the near-bed hydraulics in these units. The research was completed in three restored reaches and one reference reach at the Virginia Tech Stream Research, Education, and Management Laboratory. The laboratory is unique because three different restoration treatments were applied contiguously along a stream, and the restoration practices ranged from passive to active. The passive reach included cattle exclusion, while the active reaches included cattle exclusion as well as vegetation plantings, bank sloping and the construction of inset floodplains. Three-dimensional velocities were measured near the channel bed in run and glide biotopes within the three restored reaches, as well as an upstream reference reach. The velocities were utilized to analyse and compare near-bed turbulent structure across the reaches. While the restoration activities did not address the channel bed directly, differences in physical structure of the two physical biotopes were observed among restoration treatments, likely because of changes in bank shape and roughness due to vegetation differences. Differences between reference and restored reaches were still evident approximately 3 years after cattle exclusion and construction activities. Few differences were observed in the hydraulic structure between runs and glides, and the near-bed flow structure in both runs and glides was related to local roughness. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to evaluate the influence of manual versus mechanical glide path (GP) on the surface changes of two different nickel-titanium rotary instruments used during root canal therapy in a moderately curved root canal. Materials and Methods: Sixty systemically healthy controls were selected for the study. Controls were divided randomly into four groups: Group 1: Manual GP followed by RaCe rotary instruments, Group 2: Manual GP followed by HyFlex rotary instruments, Group 3: Mechanical GP followed by RaCe rotary instruments, Group 4: Mechanical GP followed by HyFlex rotary instruments. After access opening, GP was prepared and rotary instruments were used according to manufacturer's instructions. All instruments were evaluated for defects under standard error mean before their use and after a single use. The scorings for the files were given at apical and middle third. Statistical Analysis Used: Chi-squared test was used. Results: The results showed that there is no statistical difference between any of the groups. Irrespective of the GP and rotary files used, more defects were present in the apical third when compared to middle third of the rotary instrument. Conclusion: Within the limitations of this study, it can be concluded that there was no effect of manual or mechanical GP on surface defects of subsequent rotary file system used. [ABSTRACT FROM AUTHOR]

Landing is an important but understudied behavior that flying animals must perform constantly. In still air, insects decelerate smoothly prior to landing by employing the relatively simple strategy of maintaining a constant rate of image expansion during their approach. However, it is unclear whether insects employ this strategy when faced with challenging flight environments. Here, we tested the effects of wind on bumblebees (Bombus impatiens) landing on flowers. We find that bees' approach paths to flowers shift from multidirectional in still air to unidirectional in wind, regardless of flower orientation. In addition, bees landing in a 3.5 m s-1 headwind do not decelerate smoothly, but rather maintain a high flight speed until contact, resulting in higher peak decelerations upon impact. These findings suggest that wind has a strong influence on insect landing behavior and performance, with important implications for the design of micro aerial vehicles and the ecomechanics of insect flight. [ABSTRACT FROM AUTHOR]

Introduction The purpose of this study was to compare centering ability and apical canal transportation of K-files (KF), ProGlider (PG), and G-Files (GF) after glide path enlargement in curved canals by using micro–computed tomography. Methods Thirty canals each were randomly assigned to KF, GF, and PG. Teeth were scanned before and after glide path enlargement to compare centering ability at 3 levels: 1 mm (D1) and 7 mm (D7) from the apical foramen and at the point of maximum root curvature (Dmc). Transportation was assessed in 8 directions at D1. Results KF were significantly less centered than both nickel-titanium (NiTi) groups at D1. At Dmc, PG exhibited a significantly more centered enlargement than both GF and KF, which were significantly similar. At D7, PG was significantly more centered than KF, but there were no significant differences between GF and KF or between PG and GF ( P < .016). KF exhibited significantly more canal transportation at D1 than the NiTi groups ( P < .05). Conclusions NiTi files cause less transportation than KF. At D1, KF was less centered than both NiTi files. PG remained more centered at Dmc and D7. [ABSTRACT FROM AUTHOR]

In this paper, an approach that considered both the continuous and discrete variables using the Gauss pseudospectral method is presented for multiphase trajectory optimization of gun-launched glide guided projectiles. The entire projectile trajectory is divided into four flight phases that connect to each other sequentially to ensure continuity. Continuous variables are utilized to describe the projectile’s state and control. Meanwhile, discrete variables are proposed to express the initial flight path angle and switching times between different flight phases. The trajectory optimization problem is posed as a constrained multiphase nonlinear optimal control problem, which is then transcribed into a nonlinear programming problem using the Gauss pseudospectral method and is finally solved using the interior point algorithm. Simulation results demonstrate the feasibility and effectiveness of this approach, as well as a detailed analysis of the key features of the trajectory parameters. [ABSTRACT FROM AUTHOR]

Introduction The aim of the present study was to evaluate the cyclic fatigue resistance of the WaveOne Gold Glider (Dentsply Maillefer, Ballaigues, Switzerland), R-Pilot (VDW, Munich, Germany), and ProGlider (Dentsply Maillefer) glide path instruments. Methods Ten instruments from each glide path system were included in the study. A stainless steel artificial canal with a 90° angle and a 3-mm radius of curvature was used for the testing process. The working lengths of the instruments were fixed at 19 mm, and the instruments were operated using an endodontic motor (X-Smart Plus, Dentsply Maillefer) at recommended setting for each. A digital camera (Sony HDR-XR260; Sony Corporation, Minato, Tokyo, Japan) was positioned on the top of the cyclic fatigue test device, and the time to fracture was recorded in seconds by means of the video camera. For each instrument, the number of cycles to failure was calculated, and the length of the fractured fragment was measured. The data were analyzed using 1-way analysis of variance followed by the post hoc Tukey test. Results Statistically significant differences in the number of cycles to failure values were observed across the tested groups; the ranking of the instruments was as follows: WaveOne Gold Glider > R Pilot > ProGlider ( P < .05). There was no significant difference in the mean length of the fractured fragment of the instruments ( P > .05). Conclusions Within the limitations of the present study, it can be concluded that improved alloy properties and reciprocating motion could enhance the cyclic fatigue resistance of glide path instruments. [ABSTRACT FROM AUTHOR]

Introduction The aim of this study was to compare the glide path preparation times of stainless steel hand files, PathFiles (Dentsply Sirona, Ballaigues, Switzerland), and the WaveOne Gold Glider (Dentsply Sirona). The preparation times for final root canal shaping with the Primary WaveOne Gold instrument in extracted human molar teeth with and without prior glide path preparation were also recorded and compared. Methods Mesiobuccal canals of 60 extracted human mandibular molars (curvature angles between 25° and 35° and radii <10 mm) were selected and randomly divided into 4 groups with 15 canals each. Canals were negotiated to patency with a #8 K-file. Canal preparations were performed by a single operator using precurved #10-15-20 stainless steel manual K-files (the K-file group), a #10 stainless steel manual K-file followed by PathFiles #1-3 (the PathFile group), a #10 stainless steel manual K-file followed by WaveOne Gold Glider (the WaveOne Gold Glider group), or no further glide path preparation. Final canal preparation of all 60 canals was performed with the Primary WaveOne Gold instrument. Glide path and final preparation times were recorded. Results Glide path enlargement was statistically significantly fastest in the WaveOne Gold Glider group (19.7 ± 5.6 seconds) followed by the PathFile group (41.0 ± 6.8 seconds) and then the K-file group (81.2 ± 26.3 seconds) using analysis of variance (ANOVA) and Kruskal-Wallis tests ( P < .0001). No statistically significant difference in the mean final preparation times was found among the WaveOne Gold Glider (23.1 ± 6.0 seconds), PathFile (24.4 ± 4.9 seconds), and K-file groups (27.2 ± 9.5 seconds). All 3 groups were statistically significantly faster than the no glide path preparation group (35.4 ± 10.2 seconds) using ANOVA ( P = .0004) and Kruskal-Wallis tests ( P = .0010). Conclusions Preparation time with the Primary WaveOne Gold file was statistically significantly reduced when the file was used in combination with any of the glide path preparation techniques. The WaveOne Gold Glider performed statistically significantly faster in glide path preparation time than the other glide path preparation techniques. [ABSTRACT FROM AUTHOR]

Introduction Securing a reproducible glide path before instrumentation is recommended to maintain the original geometry of the root canal system and to prevent file separation. Mechanical glide path management systems have been introduced to expedite this step. The aim of this study was to compare apical transportation, canal volume increase, and working time during glide path management with ProGlider (PG; Dentsply Tulsa Dental Specialties, Tulsa, OK) and PathFiles (PF, Dentsply Tulsa Dental Specialties). Methods Forty curved mesial canals of mandibular molars were randomly allocated into 2 experimental groups ( n = 20) according to the glide path management system: PG or PF. A glide path was achieved according to the manufacturers' protocol. Micro–computed tomographic analysis was performed to assess apical transportation at 1, 3, and 5 mm and volume increase. The time required to achieve the glide path was measured. Results The overall apical transportation mean values (± standard error) were 13.33 ± 3.37 μm for PG and 19.21 ± 4.4 μm for PF ( P > .05). The mean (± standard error) volume increase values were 0.49 ± 0.06 mm 3 for PG and 0.48 ± 0.06 mm 3 for PF ( P > .05). A statistically significant difference in the working time was found between the groups ( P < .0001) where the mean (± standard error) values for time were 7.38 ± 1.73 seconds for PG and 20.61 ± 5.54 seconds for PF. Conclusions Similar apical transportation and volume increase occurred during glide path management with PG single-file and PF multi-file systems; however, PG achieved glide path faster than PF. [ABSTRACT FROM AUTHOR]

Precision placement of guided airdrop systems necessarily requires some mechanism enabling effective directional control of the vehicle. Often this mechanism is realized through asymmetric deflection of the parafoil canopy trailing- edge brakes. In contrast to conventional trailing-edge deflection used primarily for lateral steering, upper-surface bleed air spoilers have been shown to be extremely effective for both lateral and longitudinal (i.e., glide slope) control of parafoil and payload systems. Bleed air spoilers operate by opening and closing several spanwise slits in the upper surface of the parafoil canopy, thus creating a virtual spoiler from the stream of expelled ram air. The work reported here considers the autonomous landing performance of a small-scale parafoil and payload system using upper-surface bleed air spoilers exclusively for both lateral steering and glide slope control. Landing accuracy statistics computed from a series of Monte Carlo simulations in a variety of atmospheric conditions and experimental flight tests were found to be in good agreement. Median miss distances for the combined lateral and longitudinal control logic are on the order of 13 m, indicating an improvement in landing accuracy of nearly 50 % over similar systems employing only lateral steering control. [ABSTRACT FROM AUTHOR]

A new method has been developed for predicting and controlling the ground range of an unpowered reusable launch vehicle. The key feature is the use of the quasi-equilibrium glide condition to create a database of range-to-go versus energy for different values of the glide-efficiency factor. Downtrack range to runway touchdown is predicted by performing a two-dimensional table lookup of the range-to-go database. Unlike most predictor--corrector guidance methods, the proposed ground-range guidance scheme does not require onboard numerical integration of the governing equations of motion. Another key element is the coupling between the latter stages of the traditional terminal area energy management phase and the entire approach and landing phase, where the flare-to-touchdown maneuver is concisely parameterized by an exponential altitude profile. Numerical simulations demonstrate that this new method can accurately and reliably guide the vehicle to the desired touchdown conditions despite large errors in the initial states, large errors in the initial downtrack distance to the runway, and aerodynamic drag dispersions. [ABSTRACT FROM AUTHOR]

The paper describes the automatic control of an aircraft in the longitudinal plane during landing, taking into account sensor errors and disturbances. Aircraft auto-landing is achieved by combining H2 and H∞ control techniques, thereby obtaining a robust H2/H∞ controller. It provides good precision tracking and robust stability with respect to the uncertainties caused by different disturbances and noise-type signals. The weights of the H2 and H∞ control techniques within the robust H2/H∞ controller are adjusted so that the aircraft accurately tracks the desired trajectory during the two main stages of the landing process. The theoretical results are validated by numerical simulations for the landing of a Boeing; the results are very good (Federal Aviation Administration accuracy requirements for Category III are met) and prove the robustness of the new auto-landing system even in the presence of disturbances and sensor errors. [ABSTRACT FROM AUTHOR]

The goal of this paper is the analytical validation of a model of Cermelli and Gurtin [Arch. Ration. Mech. Anal., 148 (1999), pp. 3-52] for an evolution law for systems of screw dislocations under the assumption of antiplane shear. The motion of the dislocations is restricted to a discrete set of glide directions, which are properties of the material. The evolution law is given by a "maximal dissipation criterion," leading to a system of differential inclusions. Short time existence, uniqueness, cross-slip, and fine cross-slip of solutions are proved. [ABSTRACT FROM AUTHOR]

Endodontic glide path is the creation of a smooth patency from canal orifice to apex, which can be performed manually or with small tapered NiTi rotary instruments. The use of stainless steel (SS) hand K-files inserted in a reciprocating handpiece can be a possible alternative to create a mechanical glide path. The aim of this study was to compare the cyclic fatigue resistance between SS K-files used in a reciprocating motion and NiTi rotary instruments in artificial curved canals. Ten SS size 15 K-files used with the M4 handpiece (SybronEndo, Glendora, CA, USA) and ten PathFiles (Maillefer-Dentsply, Ballaigues, CH, Switzerland) NiTi rotary instruments size 16, 0.02 taper were tested for resistance to cyclic fatigue. The time to fracture inside an artificial curved canal was recorded for each instrument. Data were analyzed by one-way ANOVA and Tukey HSD test. Mean time (and SD) to failure was 464 s (±40.4) for the Group PF (NiTi rotary PathFile), and 1049 s (±24.8) for the Group M4 (SS K-files reciprocating) with a statistically significant difference between the two groups ( p = 0.033). The SS 15 K-files used with the M4 handpiece showed a significant greater resistance to cyclic fatigue when compared to the NiTi rotary PathFiles. Therefore, the use of small size SS files in a reciprocating motion might be a rational choice for the creation of a mechanical endodontic glide path in curved root canals. [ABSTRACT FROM AUTHOR]

Introduction The purpose of this study was to evaluate and compare the volume of removed dentin, transportation, and centering ability of ProTaper Next (PTN) system with and without glide path preparation by using cone-beam computed tomography (CBCT) imaging. Methods Sixty mesiobuccal canals of mandibular first molars with curvatures of 25°−35° were divided into 3 experimental groups ( n = 20) according to the instrumentation technique as follows: group PG/PTN (glide path was created with ProGlider [PG]) and canals were shaped with PTN system), group PF/PTN (glide path was created with PathFile [PF]) and canals were shaped with PTN system), and group PTN (glide path was not performed and canals were shaped with PTN system only). Canals were scanned before and after instrumentation by using CBCT scanner to evaluate root canal transportation and centering ratio at 3, 5, and 7 mm from the apex and volumetric changes. Data were statistically analyzed, and the significance level was set at P < .05. Results There was no significant difference among the tested groups regarding the volume of removed dentin and centering ratio ( P > .05). At 3-mm and 5-mm levels, the PG/PTN group showed a significantly lower mean transportation value among the groups ( P < .05). However, at 7-mm level, there was no significant difference in canal transportation among the groups ( P > .05). Conclusions PG/PTN instrumentation method revealed better performance with fewer canal aberrations when compared with instrumentation performed with PF/PTN or PTN only. [ABSTRACT FROM AUTHOR]

Introduction The objective of this study was to compare the shaping ability of different rotary and reciprocating nickel-titanium file systems with and without previous glide path preparation in simulated S-shaped canals. Methods One hundred twenty S-shaped canals in resin blocks were prepared to an apical size 25 by using Reciproc, WaveOne, HyflexCM, F360, and OneShape systems either with or without previous glide path preparation (Pathfile) (12 canals/group). Material removal was measured at 20 measuring points, beginning 1 mm from the end point of preparation. Incidence of canal aberrations (zip/elbow, ledge formation), preparation time, and instrument failures were also recorded. Statistical analyses were performed by using analysis of variance and Tukey and χ² tests. Results For all systems, glide path preparation exerted no significant effect on preparation times (P > .05). Glide path preparation had no influence on the incidence of canal aberrations and instrument fractures (P > .05), with no significant differences between the 5 systems (P > .05). Glide path preparation had no influence on the centering ability of all systems (P > .05). On average, canals prepared with F360, OneShape, and HyflexCM remained better centered compared with those enlarged with WaveOne and Reciproc. Conclusions Under the conditions of this study, glide path preparation had no significant impact on canal straightening. Less tapered instruments maintained the original canal curvature better than instruments having greater tapers. [ABSTRACT FROM AUTHOR]

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Abstract: This paper analyses data on occupants׳ movement on stair landings collected during an evacuation drill performed in a six-storey office building in the United States. A total of 215 occupant travel path trajectories were filmed and time on the stair landings and egress behaviours were analysed. Data were analysed using a probabilistic approach, i.e., the probability of different occupant travel paths were calculated in relation to two different factors: (1) crowding on the landings, and (2) the type of interactions between occupants (e.g., merging flows, deference/overtaking behaviours, etc.). Results showed that a higher number of occupants on stair landings caused an increase in the probability for (1) longer travel paths and (2) usage of the outer boundaries on the stair/landing connections. This paper highlights that data and modelling assumptions should be used after a careful evaluation of their field of applicability. In the case of a low occupant load and non-homogenous merging streams (a higher number of people entering the landing from the stairs than the door), floors tend to be emptied from the top to the bottom. [Copyright &y& Elsevier]

Zirconium is an important metal for internal components of nuclear reactors, yet there have been few computer simulation studies of the interaction between dislocations and interstitial dislocation loops that are created in this metal by radiation damage. Reaction mechanisms have been simulated in this work by using an interatomic potential developed by Mendelev and Ackland (2007 Phil. Mag. Lett. 87 349) that has been shownto provide a good description of the core structure and glide resistance of dislocations on the principal slip plane {1 1 0 0}. The interaction of both edge and screw dislocations of the 〈 1 1 2 0 〉{1 1 0 0} slip system with small prismatic loops containing up to 156 interstitial atoms has been considered. If a loop intersects the dislocation glide plane it becomes absorbed on the dislocation line in most situations. If it does not intersect the glide plane but has a Burgers vector inclined to that of the dislocation, it glides to and is absorbed by the line in most cases. The obstacle resistance of loops is relatively strong for screw dislocations in comparison with edges, but loop absorption by screws is only temporary. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: This study compared the incidence of deviation along S-shaped (double-curved) canals after glide path preparation with 2 nickel-titanium (NiTi) rotary pathfinding instruments and hand K-files. Methods: S-shaped canals from 60 training blocks were filled with ink, and preinstrumentation images were obtained by using a stereomicroscope. Glide path preparation was performed by an endodontist who used hand stainless steel K-files (up to size 20), rotary NiTi PathFile instruments (up to size 19), or rotary NiTi Scout RaCe instruments (up to size 20). Postinstrumentation images were taken by using exactly the same conditions as for the preinstrumentation images, and both pictures were superimposed. Differences along the S-shaped canal for the mesial and distal aspects were measured to evaluate the occurrence of deviation. Results: Intragroup analysis showed that all instruments promoted some deviation in virtually all levels. Overall, regardless of the group, deviations were observed in the mesial wall at the canal terminus and at levels 4, 5, 6 and 7 mm and in the distal wall at levels 1, 2, and 3 mm. These levels corresponded to the inner walls of each curvature. Both rotary NiTi instruments performed significantly better than hand K-files at all levels (P < .05), except for PathFiles at the 0-mm level. ScoutRaCe instruments showed significantly better results than PathFiles at levels 0, 2, 3, 5, and 6 mm (P < .05). Conclusions: Findings suggest that rotary NiTi instruments are suitable for adequate glide path preparation because they promoted less deviation from the original canal anatomy when compared with hand-operated instruments. Of the 2 rotary pathfinding instruments, Scout RaCe showed an overall significantly better performance. [Copyright &y& Elsevier]

We obtain the singular asymptotic behavior of the stress field in the vicinity of a non-planar dislocation in three dimensions and the nearly singular behavior of the full self-force of the dislocation including both glide and climb forces, using asymptotic analysis. We also derive asymptotic formulas for the stress field in the vicinity of a curved dislocation segment. Numerical examples are presented to examine the asymptotic formulas. The obtained formulas can be used for qualitative understanding of the stress tensor associated with dislocations and efficient and accurate calculation of the stress tensor in dislocation dynamics simulations. [ABSTRACT FROM PUBLISHER]