Gyrofluid simulations of collisionless reconnection in the presence of diamagnetic effects

The effects of the ion Larmor radius on magnetic reconnection are investigated by means of numerical simulations, with a Hamiltonian gyrofluid model. In the linear regime, it is found that ion diamagnetic effects decrease the growth rate of the dominant mode. Increasing ion temperature tends to make the magnetic islands propagate in the ion diamagnetic drift direction. In the nonlinear regime, diamagnetic effects reduce the final width of the island. Unlike the electron density, the guiding center density does not tend to distribute along separatrices and at high ion temperature, the electrostatic potential exhibits the superposition of a small scale structure, related to the electron density, and a large scale structure, related to the ion guiding-center density

Gyrofluid simulations of collisionless reconnection in the presence of diamagnetic effects

The effects of the ion Larmor radius on magnetic reconnection are investigated by means of numerical simulations, with a Hamiltonian gyrofluid model. In the linear regime, it is found that ion diamagnetic effects decrease the growth rate of the dominant mode. Increasing ion temperature tends to make the magnetic islands propagate in the ion diamagnetic drift direction. In the nonlinear regime, diamagnetic effects reduce the final width of the island. Unlike the electron density, the guiding center density does not tend to distribute along separatrices and at high ion temperature, the electrostatic potential exhibits the superposition of a small scale structure, related to the electron density, and a large scale structure, related to the ion guiding-center density

Gyrofluid simulations of collisionless reconnection in the presence of diamagnetic effects

The effects of the ion Larmor radius on magnetic reconnection are investigated by means of numerical simulations, with a Hamiltonian gyrofluid model. In the linear regime, it is found that ion diamagnetic effects decrease the growth rate of the dominant mode. Increasing ion temperature tends to make the magnetic islands propagate in the ion diamagnetic drift direction. In the nonlinear regime, diamagnetic effects reduce the final width of the island. Unlike the electron density, the guiding center density does not tend to distribute along separatrices and at high ion temperature, the electrostatic potential exhibits the superposition of a small scale structure, related to the electron density, and a large scale structure, related to the ion guiding-center density

Mediastinitis and sternal prosthesis infection successfully treated by minimally invasive omental flap transposition

Purulent mediastinitis is a possible serious complication after mediastinal surgery. We report the case of a localized sternal plasmocytoma treated by sternectomy and prosthetic repair, who needed a second surgery for a fistulizing mediastinitis. Five months earlier, in another Hospital, the patient underwent sternal resection and reconstruction with a “sandwich” prosthesis (Methyl-methacrylate and Marlex mesh). Suppurative mediastinitis occurred and septic shock resolution was observed after the spontaneous opening of a mediastinal cutaneous fistula. After referring to our Unit the patient underwent extensive local and systemic preparation and nutritional support; the infected prosthesis was then removed and the gap filled by a laparoscopically-prepared omental flap. Adequate preoperative management, removal of any infected material and minimally invasive omental flap transposition allowed the successful treatment of this life-threatening condition

On the use of projectors for Hamiltonian systems and their relationship with Dirac brackets

The role of projectors associated with Poisson brackets of constrained Hamiltonian systems is analyzed. Projectors act in two instances in a bracket: in the explicit dependence on the variables and in the computation of the functional derivatives. The role of these projectors is investigated by using Dirac's theory of constrained Hamiltonian systems. Results are illustrated by three examples taken from plasma physics: magnetohydrodynamics, the Vlasov-Maxwell system, and the linear two-species Vlasov system with quasineutrality

Relation of Birthweight and Ovarian and Uterine Size Prior to Menarche

During pregnancy, supply of nutrients and exposure of the mother to environmental factors can influence fetus phenotype, possibly modifying growth of fetal tissues and organs. Few studies inconsistently reported that fetuses exposed to an insufficient energy supply, as those born small for gestational age, may have a reduced volume of uterus and ovaries. A retrospective analysis was performed on ultrasound data performed between 2012 and 2018 in 69 young premenarchal girls, 5 to 9\ua0years of age, attending our endocrine\u2013gynecologic clinic for a suspect of early puberty. Length of pregnancy and birthweight was also retrieved. When corrected for age, and presence of ovarian follicles, ovarian volume was positively (R2 = 0.210; p = 0.001) related to percentiles of birthweight (beta coefficient 0.012; 95% CI, 0.002\u20130.021). Similarly, uterine volume was positively (R2 = 0.237; p = 0.005) related to percentiles of birthweight (beta coefficient 0.067; 95% CI, 0.021\u20130.114). Ovarian (p = 0.034) and uterine (p = 0.014) volume was higher in the upper 3rd distribution of birthweight percentiles. In conclusion, development of ovarian and uterine volume increases progressively with the increase of birthweight percentiles. The data indicate an association between birthweight and the volume of uterus and ovary at 5\u20139\ua0years of age

Matter from light-light scattering via Breit-Wheeler events produced by two interacting Compton sources

We present the dimensioning of a photon-photon collider based on Compton gamma sources for the observation of Breit-Wheeler pair production and QED \u3b3\u3b3 events. Two symmetric electron beams, generated by photocathodes and accelerated in linacs, produce two gamma ray beams through Compton back scattering with two J-class lasers. Tuning the system energy above the Breit-Wheeler cross section threshold, a flux of electron-positron pairs is generated out of light-light interaction. The process is analyzed by start-to-end simulations. Realistic numbers of the secondary particle yield, referring to existing state-of-the-art set-ups and a discussion of the feasibility of the experiment taking into account the background signal are presented

Fluid geochemistry and seismic activityin the period 1998-2002 at Turrialba Volcano (Costa Rica)

Turrialba Volcano, located in Central-Southern Costa Rica, has been characterized, since the last period of eruptive activity in 1884-1886, by a weak and discontinuous fumarolic activity in the western area of its summit. During the 1998-2002 period, fumaroles discharging from central and West craters were collected for chemical analyses of major and trace gas compounds, 13C/12C in CO2 and 18O/16O and D/H (in one fumarolic condensate), isotopic ratios. Geophysical measurements (seismic activity and ground deformation), monitored in the same period, were compared to geochemical data to define the status of the volcanic system. Chemical and isotopic characteristics of fumaroles of Turrialba Volcano seem to be related to interaction processes between a magmatic source and a shallower hydrothermal aquifer. Since February 1997, seismicity at Turrialba Volcano gradually increased, while since August 2001 new fumaroles start to discharge from a new fracture system located in the area between central and West craters. Since September 2001, strong compositional changes of gas discharges have been recorded at central crater. These occurrences are possibly due to variations in the permeability of the conduit system feeding the fumaroles. Heat pulse episodes from a magmatic source have possibly caused the increase of vapour pressure at depth and, consequently, favoured the uprising of the magmatic fluids toward the surface. The observed evolution of chemical and physical parameters suggests that to forecast a possible renewal of the volcanic activity in the near future a full program of both geochemical and geophysical surveillance must be provided at Turrialba Volcano

Gyrofluid simulations of collisionless reconnection in the presence of diamagnetic effects

International audienceThe effects of the ion Larmor radius on magnetic reconnection are investigated by means of numerical simulations, with a Hamiltonian gyrofluid model. In the linear regime, it is found that ion diamagnetic effects decrease the growth rate of the dominant mode. Increasing ion temperature tends to make the magnetic islands propagate in the ion diamagnetic drift direction. In the nonlinear regime, diamagnetic effects reduce the final width of the island. Unlike the electron density, the guiding center density does not tend to distribute along separatrices and at high ion temperature, the electrostatic potential exhibits the superposition of a small scale structure, related to the electron density, and a large scale structure, related to the ion guiding-center density

Stage-related outcome for thymic epithelial tumours

Background: Thymic epithelial tumours (TETs) are characterized by a wide variety of biological behaviors. Radical resection and stage are strong prognostic factors. Aim of this study is to review our Single Center Experience. Methods: One hundred and seventy-seven patients observed in the period from January 2000 to December 2016 were included in the study. Data regarding clinicopathologic features, treatment, and survival were collected. Stage-related clinical standpoints and therapeutic options were also evaluated. Results: Non-surgical treatment was primarily performed in 15 (8.47%), unresectable disease was intraoperatively found in 12 cases (7.4%). The analysis of 150 patients undergoing curative surgery revealed 70 stage I TET (46.66%), 49 stage II (32.66%), 19 stage III (12.66%), 6 stage IVa (4%) and 6 stage IVb (4%) at the first hospital admission. Histology identified 12 A thymoma (8%), 38 AB (25.33%), 24 B1 (16%), 50 B2 (33.33%), 19 B3 (12.66%) and 7 carcinomas (4.66%). The mean follow up time was 84.14 months (sd = 61.68 months). Disease relapse occurred in 13 patients (8.78%) at a mean period of 78.85 months (sd = 60.87 months) after surgery. Exitus due to thymoma happened in 6 cases (4.05%) after a mean survival of 56.02 months (sd = 25.17 months). The 5-year overall survival rate was 0.94 (95%CI 0.88-0.97) and the 5-year disease-free survival rate was 0.90 (95%CI 0.83-0.94). The 5-year overall survival rates were 96.1% (95% CI, 89.9-98.5%) for the early stages and 87.4% (95% CI, 65.6-95.8%) for the advanced stages (p = 0.670). The 5-year disease-free survival rates resulted being 98.8% (95% CI, 92.3-99.8%) for the early stages and 59.8% (95% CI, 37.8-76.2%) for the advanced stages (p < 0.001). Conclusions: Advanced stage TETs are characterized by higher mortality and recurrence rates. Although technically demanding, surgery, as part of multimodality therapy, could prolong survival. Iterative surgical treatment of recurrences is a viable option for selected patients. Trial registration: The study was approved by the Institutional Review Board of Perugia and Terni University Hospitals [Code T1003] and was retrospectively registered