On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Measurement of prompt D0^{0} and D‾\overline{D}0^{0} meson azimuthal anisotropy and search for strong electric fields in PbPb collisions at root SNN\sqrt{S_{NN}} = 5.02 TeV

The strong Coulomb field created in ultrarelativistic heavy ion collisions is expected to produce a rapiditydependent difference (Av2) in the second Fourier coefficient of the azimuthal distribution (elliptic flow, v2) between D0 (uc) and D0 (uc) mesons. Motivated by the search for evidence of this field, the CMS detector at the LHC is used to perform the first measurement of Av2. The rapidity-averaged value is found to be (Av2) = 0.001 ? 0.001 (stat)? 0.003 (syst) in PbPb collisions at ?sNN = 5.02 TeV. In addition, the influence of the collision geometry is explored by measuring the D0 and D0mesons v2 and triangular flow coefficient (v3) as functions of rapidity, transverse momentum (pT), and event centrality (a measure of the overlap of the two Pb nuclei). A clear centrality dependence of prompt D0 meson v2 values is observed, while the v3 is largely independent of centrality. These trends are consistent with expectations of flow driven by the initial-state geometry. ? 2021 The Author. Published by Elsevier B.V. This is an open access article under the CC BY licens

Observation of electroweak production of Wγ with two jets in proton-proton collisions at √s = 13 TeV

A first observation is presented for the electroweak production of a W boson, a photon, and two jets in proton-proton collisions. The W boson decays are selected by requiring one identified electron or muon and an imbalance in transverse momentum. The two jets are required to have a high dijet mass and a large separation in pseudorapidity. The measurement is based on data collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The observed (expected) significance for this process is 4.9 (4.6) standard deviations. After combining with previously reported CMS results at 8 TeV, the observed (expected) significance is 5.3 (4.8) standard deviations. The cross section for the electroweak W$_{γjj}$ production in a restricted fiducial region is measured as 20.4 +/- 4.5 fb and the total cross section for W$_{γ}$ production in association with 2 jets in the same fiducial region is 108 +/- 16 fb. All results are in good agreement with recent theoretical predictions. Constraints are placed on anomalous quartic gauge couplings in terms of dimension-8 effective field theory operators

Measurements of production cross sections of polarized same-sign W boson pairs in association with two jets in proton-proton collisions at s=13 TeV

The first measurements of production cross sections of polarized same-sign W±W±boson pairs in proton-proton collisions are reported. The measurements are based on a data sample collected with the CMS detector at the LHC at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 137fb−1. Events are selected by requiring exactly two same-sign leptons, electrons or muons, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass to enhance the contribution of same-sign W±W±scattering events. An observed (expected) 95% confidence level upper limit of 1.17 (0.88)fbis set on the production cross section for longitudinally polarized same-sign W±W±boson pairs. The electroweak production of same-sign W±W±boson pairs with at least one of the Wbosons longitudinally polarized is measured with an observed (expected) significance of 2.3 (3.1) standard deviations.SCOAP

Evaluation of the amount of apically extruded debris during retreatment of root canals filled by different obturation techniques

Objective: To evaluate the amount of apically extruded debris during retreatment (with or without solvent) of root canals filled by two obturation techniques. Materials and Methods: Forty-eight root canals were prepared using ProTaper Universal F3 and filled with Gutta-percha and AH 26 sealer using single cone or lateral condensation techniques. The root canal fillings were removed using ProTaper Universal Retreatment system with or without solvent, and the canals were further prepared with ProTaper F4. The operating time was measured. The debris extruded was collected into preweighed Eppendorf tubes. The dry weight of the extruded debris was calculated by subtracting the weight of the empty tube from that of the tube containing debris. Statistical analysis was performed with two-way analysis of variance test, with Bonferroni correction at a 95% confidence level. Results: There was no statistically significant difference in the amount of extruded debris between the two obturation techniques ( P = 0.332). The mean amount of debris was higher in the nonsolvent groups than the solvent groups, particularly with the single cone technique ( P = 0.013). There was a significant difference between groups with regard to the retreatment time ( P 0.001). Gutta-percha removal took less time in the single cone group than in the lateral condensation group ( P 0.001). Gutta-percha removal in the nonsolvent groups took significantly less time than that in the solvent groups ( P 0.001). Conclusions: The amounts of apically extruded debris were similar in both obturation techniques. A greater amount of apically extruded debris was observed in the nonsolvent groups than the solvent groups

Evaluation of microcrack formation in root canals after instrumentation with different NiTi rotary file systems: A scanning electron microscopy study

The aim of this study was to evaluate the dentinal microcrack formation of ProTaper Universal, ProTaper Next, and WaveOne. Sixty extracted mandibular molars were selected. The mesial roots were resected and randomly divided into four groups (n=15). The canals were prepared with hand files (group 1), ProTaper Universal (group 2), ProTaper Next (group 3), and WaveOne (group 4) instrument systems. The roots were separated horizontally at 3, 6, and 9mm from the apex. Digital images were captured at ×40 magnification using scanning electron microscopy to detect microcrack formation. Statistical analysis was performed by Pearson Chi-square test. The prevalence of microcracks in group 2, group 3, and group 4 were significantly higher when compared to group 1 (p0.05) in all sections. All instruments caused microcracks except for hand file. The highest percentage of microcrack was recorded in 3mm section for all groups. © 2014 Wiley Periodicals, Inc

Efficacy of three irrigation agitation techniques on bacterial elimination: A microbiologic and microscopic evaluation

The aim of this study was to compare in vitro reduction of Enterococcus faecalis by using three agitation methods. Fifty-five mandibular premolar teeth were used. The root canals were prepared by using ProTaper instruments to size F4. Fresh bacterial suspensions were inoculated into each canal and the teeth were incubated at 37°C under aerobic conditions for 3 weeks. The specimens in negative control group were not contaminated and the teeth in positive control receive no further instrumentation or irrigation after contamination. The contaminated teeth were divided into three experimental groups and two control groups. The experimental groups were as follows according to agitation of NaOCl irrigation solution; group 1, the brush-covered NaviTip FX needle; group 2, EndoVac apical negative pressure irrigation system; and group 3, self-adjusting file (SAF). Following the final irrigation, samples obtained with sterile #40 H-file from teeth and the file used were placed into sterile microcentrifuge tubes. After the incubation period, bacterial colony numbers were noted as CFU/ml. Three teeths were randomly selected from each group for scanning electron microscope evaluation. The three groups were compared with the Kruskal-Wallis test. Comparisons between three groups were made with the Mann-Whitney U-test with Bonferroni correction. SAF was significantly effective in elimination of E. faecalis when compared to EndoVac (p0.05). In conclusion, agitation of NaOCl with SAF for 2 min may be an effective alternative approach. © 2014 Wiley Periodicals, Inc

The effect of glide path on the surface quality of new and used rotary and reciprocating single files: OneShape versus WaveOne

The aim of this study was to evaluate the effect of glide path preparation on the surface topography changes of WaveOne and OneShape single files using atomic force microscopy analysis. Two commercially available brands of single file systems were analyzed, including 15 specimens/brand as following: Group I; WaveOne 0.08/25 (Dentsply Maillefer, Ballaigues, Switzerland) and Group II; OneShape 0.06/25 (Micro Mega, Besançon, France). In each group, 3 new files were subjected to AFM analysis as received from manufacturer, and 12 files were analyzed after preparation of root canals. A total of 20 human maxillary molar teeth were selected. In each group, 12 files were divided into 4 subgroups according to instruments that were used in one or three root canals with or without a previous glide path (n3). After preparation the surface analysis of single files was performed on 11 different points located along a 3-mm section starting at the tip of each file using AFM. Root mean square (RMS) values were recorded to investigate the surface features of endodontic files. The differences between RMS values were tested by one-way ANOVA. There was no statistically significant difference between the groups (p>0.05). Creation of a glide path did not affect the surface topography of single file systems. © 2014 Wiley Periodicals, Inc

Influence of Diode Laser Application on the Efficiency of QMiX and EDTA Solutions in Removing Smear Layer

Objective: The aim of this study was to compare the efficacy of QMiX and ethylenediaminetetraacetic acid (EDTA) solutions with diode laser treatment in smear layer removal. Background data: Removing the smear layer from the apical thirds of root canals is difficult, regardless of the solution used. Researchers have been improved some irrigation agitation methods to overcome this challenge, and agitation of irrigants with laser devices has become popular. Methods: Seventy-five extracted mandibular premolars were used. After root canals were, prepared the specimens were divided into five groups (n = 15): Group 1, no irrigation; Group 2, 17% EDTA; Group 3, QMiX solution; Group 4, 17% EDTA with diode laser; and Group 5, QMiX with diode laser. The roots were split longitudinally and prepared for scanning electron microscopic (SEM) investigation. The smear layer was evaluated under × 500, × 1000, and × 2000 magnifications. Results: The amount of smear layer was found significantly high in the control group (p < 0.001). In the EDTA group, the amount of smear layer was significantly high at the apical thirds, and the differences among the three regions were statistically significant (p < 0.001). In the QMiX group, no difference was found between the coronal and middle thirds; however, the amount of smear layer was significantly high at the apical thirds (p < 0.001). In the EDTA plus laser and the QMiX plus laser groups, the smear layer was found significantly high at the apical thirds (p < 0.001). However, no differences were found between the coronal and middle thirds in either group. Conclusions: None of the solutions completely removed the smear layer, especially at the apical thirds. Diode laser treatment with solutions decreased the amount of smear layer, without significance. © Copyright 2015, Mary Ann Liebert, Inc. 2015