Comparing Outcomes of Robotic and Open Inguinal Lymph Node Dissection in Patients with Carcinoma of the Penis.

PURPOSE: We compared outcomes between robot-assisted video endoscopic inguinal lymphadenectomy and open inguinal lymph node dissection in patients without bulky nodal metastasis in a tandem contemporary cohort. MATERIALS AND METHODS: We retrospectively analyzed a prospectively maintained hospital registry of 51 patients who underwent robot-assisted video endoscopic inguinal lymphadenectomy and 100 treated with open inguinal lymph node dissection from 2012 to 2016 for groins without bulky nodal metastasis and who had a minimum 9-month followup. Complications were graded by the Clavien-Dindo classification, and nodal yield and disease recurrence during followup were assessed. Elastic net regression was used to select variables associated with major complications (Clavien 3a or greater) for multivariable analysis of plausible factors, including patient age, diabetes, body mass index, smoking, nodal stage, surgery type, sartorius transposition, saphenous vein transection and adjuvant radiotherapy. Penalized likelihood logistic regression methods were used for multivariate analysis to ascertain final effect sizes while accounting for sparse data bias. RESULTS: Robot-assisted video endoscopic inguinal lymphadenectomy and open inguinal lymph node dissection had comparable median lymph node yields (13 vs 12.5). No patient experienced recurrence during the median followup of 40 months. Robot-assisted video endoscopic inguinal lymphadenectomy was associated with significantly lower hospital stay, days needing a drain in situ, incidence of major complications, edge necrosis, flap necrosis and severe limb edema. On multivariable analysis pathological nodal stage (OR 2.8, 95% CI 1.1-6.8, p = 0.027) and open inguinal lymph node dissection (OR 7.5, 95% CI 1.3-43, p = 0.024) emerged as independent risk factors associated with an increased risk of major complications. CONCLUSIONS: Robot-assisted video endoscopic inguinal lymphadenectomy is a feasible technique which allows for a similar nodal yield while being associated with lower morbidity than open inguinal lymph node dissection in patients without bulky groin adenopathy.

Kappa distribution from particle correlations in nonequilibrium, steady-state plasmas.

Kappa-distributed velocities in plasmas are common in a wide variety of settings, from low-density to high-density plasmas. To date, they have been found mainly in space plasmas, but are recently being considered also in the modeling of laboratory plasmas. Despite being routinely employed, the origin of the kappa distribution remains, to this day, unclear. For instance, deviations from the Maxwell-Boltzmann distribution are sometimes regarded as a signature of the nonadditivity of the thermodynamic entropy, although there are alternative frameworks such as superstatistics where such an assumption is not needed. In this work we recover the kappa distribution for particle velocities from the formalism of nonequilibrium steady-states, assuming only a single requirement on the dependence between the kinetic energy of a test particle and that of its immediate environment. Our results go beyond the standard derivation based on superstatistics, as we do not require any assumption about the existence of temperature or its statistical distribution, instead obtaining them from the requirement on kinetic energies. All of this suggests that this family of distributions may be more common than usually assumed, widening its domain of application in particular to the description of plasmas from fusion experiments. Furthermore, we show that a description of kappa-distributed plasma is simpler in terms of features of the superstatistical inverse temperature distribution rather than the traditional parameters κ and the thermal velocity v_{th}.

Computational statistical mechanics of a confined, three-dimensional Coulomb gas.

The thermodynamic properties of systems with long-range interactions present an ongoing challenge, from the point of view of both theory as well as computer simulation. In this paper we study a model system, a Coulomb gas confined inside a sphere, by using the Wang-Landau algorithm. We have computed the configurational density of states, the thermodynamic entropy, and the caloric curve, and compared with microcanonical Metropolis simulations, while showing how concepts such as the configurational inverse temperature can be used to understand some aspects of thermodynamic behavior. A dynamical multistability behavior is seen at low energies in microcanonical Monte Carlo simulations, suggesting that flat-histogram methods can in fact be useful and complementary alternatives to traditional Metropolis simulation in complex systems.

Single-particle velocity distributions of collisionless, steady-state plasmas must follow superstatistics.

The correct modeling of velocity distribution functions for particles in steady-state plasmas is a central element in the study of nuclear fusion and also in the description of space plasmas. In this paper, a statistical mechanical formalism for the description of collisionless plasmas in a steady state is presented, based solely on the application of the rules of probability and not relying on the concept of entropy. Beck and Cohen's superstatistical framework [Beck and Cohen, Physica A 322, 267 (2003)PHYADX0378-437110.1016/S0378-4371(03)00019-0] is recovered as a limiting case, and a "microscopic" definition of inverse temperature ß is given. Nonextensivity is not invoked a priori but enters the picture only through the analysis of correlations between parts of the system.

Development of large volume double ring penning plasma discharge source for efficient light emissions.

In this paper, the development of large volume double ring Penning plasma discharge source for efficient light emissions is reported. The developed Penning discharge source consists of two cylindrical end cathodes of stainless steel having radius 6 cm and a gap 5.5 cm between them, which are fitted in the top and bottom flanges of the vacuum chamber. Two stainless steel anode rings with thickness 0.4 cm and inner diameters 6.45 cm having separation 2 cm are kept at the discharge centre. Neodymium (Nd(2)Fe(14)B) permanent magnets are physically inserted behind the cathodes for producing nearly uniform magnetic field of ~0.1 T at the center. Experiments and simulations have been performed for single and double anode ring configurations using helium gas discharge, which infer that double ring configuration gives better light emissions in the large volume Penning plasma discharge arrangement. The optical emission spectroscopy measurements are used to complement the observations. The spectral line-ratio technique is utilized to determine the electron plasma density. The estimated electron plasma density in double ring plasma configuration is ~2 × 10(11) cm(-3), which is around one order of magnitude larger than that of single ring arrangement.