Metastability for Glauber dynamics on random graphs

Analysis and Stochastic

Impaired Inhibitory Control in Recreational Cocaine Users

Chronic use of cocaine is associated with impairment in response inhibition but it is an open question whether and to which degree findings from chronic users generalize to the upcoming type of recreational users. This study compared the ability to inhibit and execute behavioral responses in adult recreational users and in a cocaine-free-matched sample controlled for age, race, gender distribution, level of intelligence, and alcohol consumption. Response inhibition and response execution were measured by a stop-signal paradigm. Results show that users and non users are comparable in terms of response execution but users need significantly more time to inhibit responses to stop-signals than non users. Interestingly, the magnitude of the inhibitory deficit was positively correlated with the individuals lifetime cocaine exposure suggesting that the magnitude of the impairment is proportional to the degree of cocaine consumed

Reduced Spontaneous Eye Blink Rates in Recreational Cocaine Users: Evidence for Dopaminergic Hypoactivity

Chronic use of cocaine is associated with a reduced density of dopaminergic D2 receptors in the striatum, with negative consequences for cognitive control processes. Increasing evidence suggests that cognitive control is also affected in recreational cocaine consumers. This study aimed at linking these observations to dopaminergic malfunction by studying the spontaneous eyeblink rate (EBR), a marker of striatal dopaminergic functioning, in adult recreational users and a cocaine-free sample that was matched on age, race, gender, and personality traits. Correlation analyses show that EBR is significantly reduced in recreational users compared to cocaine-free controls, suggesting that cocaine use induces hypoactivity in the subcortical dopamine system

THE EFFECT OF NEW INTERNAL FERRULE DESIGN PREPARATION ON THE FRACTURE RESISTANCE OF ENDODONTICALLY TREATED CENTRAL INCISORS

Statement of problem. Meny studies concerning the ferrule effect may have a significant effect on fracture resistance of endodontically treated teeth. Purpose. This study investigated the fracture resistance of endodontically treated anterior central incisors prepared with internal ferrule preparation design. Material and methods. A total of 120 extracted human maxillary central incisor were endodontically treated and divided into 10 groups of 12. Group A1 to E1 and A2 to E2 represented teeth prepared with a 0mm, 0.5mm, 1mm, 1.5mm, and 2mm internal ferrule preparation. As material for our experiments, we used Ø 1.4 - 1.6mm Y-TZP ceramics posts with retention forms in the coronary part of the post, upgraded with core build-up material (IPS E-MAX, Ivoclar, Vivadent). The experimental samples were cemented (Multilink Automix, Ivoclar), embedded in acrylic resin bloks (ProBase Polymer/Monomer, Ivoclar) and loaded at an angle of 45° degrees in an Instron Testing Machine 4301 (Instron Corp., USA) at a crosshead speed of 1mm/min until fracture. Fracture loads (N) and modes (repairable or catastrophic) were recorded. Two-way analysis of variance was used for statistical analysis with the level of significance seat p Results. The mean values (±SD) for fracture loads measured in Newtons were for the group A1: 1.4mm - 405,04N (±100.04); and A2: 1.6 mm - 503,09N (±109.01); for Group B1: 1.4mm - 401.07N (±75.02) and B2: 1.6mm - 507.13N (±101.08), for Group C1: 1.4mm - 479.01N (±109.12) and C2: 1.6mm - 567.06N (±134.37), for group D1: 1.4mm - 601.73N (±103.52) and D2: 1.6mm - 675.79N (±171.09), for Group E1: 1.4mm - 719.99N (±220.02) and E2: 1.6mm - 861.06N (±237.15). Failure patterns within those 1.4 – 1.6mm Y-TZP posts - E-MAX cores groups revealed noncatastrophic failure in group A = 100% - 100% for 0 mm, group B = 100% - 100% for 0.5mm; group C – 91.7% - 91.7% for 1mm, group D = 91.7% - 75% for 1.5mm; and 66.7% - 58.3% for 2mm both of groups E. Conclusion. With the limitations of this study, the teeth prepared without, 0.5mm and 1mm internal ferrule preparation restored with 1.4 - 1.6mm zirconia posts with retentive coronal part demonstrated significantly lower failure loads then those with 1.5 and 2mm IF. The results showed that zirconia posts with retentive coronal part and 1.5mm - 2mm internal ferrule preparation which contribute to increasing the fracture resistance of the restored root-coronary dental complex, show significance higher fracture resistance. Significant higher % of reparable fractures was determined in all of experimental groups

NEW APPROACH TO AN AESTHETIC ALL CERAMIC CONCEPT FOR RESTORATION OF FRONTAL TEETH

Purpose. This study investigated the new aesthetic all ceramic concept with a double ferrule effect. Material and methods. 36 extracted human maxillary anterior teeth were endodontically treated and divided into 3 groups of 12. Group A, B, and C represented teeth prepared with a 0mm, 1mm, and 2mm new ferrule. As a material, we used Ø 1.4 mm Y-TZP VALL posts with retention rings in the coronary part of the post. The samples were cemented (Multilink Automix, Ivoclar), embedded in acrylic resin blocks (ProBase Polymer/Monomer, Ivoclar), and loaded at an angle of 45° degrees in an Instron Testing Machine 4301 (Instron Corp., USA) at a crosshead speed of 1mm/min until fracture. Fracture loads (N) and modes (repairable or catastrophic) were recorded. Two-way analysis of variance was used for statistical analysis with the level of significance seat p\u3c0.05. Failure patterns were analyzed in the optical microscope Stereo Discovery V.8 (Carl Zeiss, Germany). Results. The mean values (±SD) for fracture loads were measured (Newtons) for group A- 405,04N (±100.04); for Group B - 479.01N (±109.12) for Group E - 719.99N (±220.02). Failure patterns within those 1.4 mm Y-TZP posts groups revealed a noncatastrophic failure in group A = 100% for 0 mm, group B – 91.7% for 1mm, and 66.7% for 2mm new ferrule. Conclusion. With the limitations of this study, the teeth prepared without, and 1mm new ferrule demonstrated significantly lower failure loads than those with 2mm. The results showed that zirconia posts with new coronal rings and 2mm new ferrule which contribute to increasing the fracture resistance of the restored teeth, show significance higher fracture resistance. A significantly higher % of reparable fractures was determined in all the experimental groups