Synchronization of dust acoustic waves in a forced Korteweg-de Vries-Burgers model.

The synchronization of dust acoustic waves to an external periodic source is studied in the framework of a driven Korteweg-de Vries-Burgers equation that takes into account the appropriate nonlinear and dispersive nature of low-frequency waves in a dusty plasma medium. For a spatiotemporally varying source term, the system is shown to demonstrate harmonic (1:1) and superharmonic (1:2) synchronized states. The existence domains of these states are delineated in the form of Arnold tongue diagrams in the parametric space of the forcing amplitude and forcing frequency and their resemblance to some past experimental results is discussed.

Evaluation of HE4 as a prognostic biomarker in uterine cervical cancer.

INTRODUCTION: Uterine cervical cancer (UCC) is the fourth most common health problem worldwide among women. Currently available biomarkers CA125, CA199, and CEA for diagnosis or prognostic evaluation of UCC have not got widespread acceptance. METHOD: Whole blood samples of 64 patients with UCC were collected along with 63 healthy females and tested for serum levels of HE4 (sHE4). A cut-off value for positive result 64.0 pmol/L was set. Statistical analysis of different clinical variables was done. RESULT: Serum level of HE4 has a significant role in the diagnosis of uterine cervical cancer. Its level increases with age, higher parity (P < 0.05), stage (P < 0.16), tumor size, and parametrial invasion. Negative result was seen with vaginal invasion, lymph node involvement & cases which had recurrence. Various histological types showed variable results. So the serum level of HE4 (sHE) level may play a role in the diagnosis & therapeutic monitoring of UCC. But the prognostic evaluation needs further studies. CONCLUSION: sHE4 is useful in the diagnosis of cervical cancer, but its prognostic significance is under the question marks. It may be associated with higher values in higher stages. Higher parity of the patient is associated with higher level of HE4 in UCC.

Rayleigh-Taylor instability in strongly coupled plasma.

Rayleigh-Taylor instability (RTI) is the prominent energy mixing mechanism when heavy fluid lies on top of light fluid under the gravity. In this work, the RTI is studied in strongly coupled plasmas using two-dimensional molecular dynamics simulations. The motivation is to understand the evolution of the instability with the increasing correlation (Coulomb coupling) that happens when the average Coulombic potential energy becomes comparable to the average thermal energy. We report the suppression of the RTI due to a decrease in growth rate with increasing coupling strength. The caging effect is expected a physical mechanism for the growth suppression observed in both the exponential and the quadratic growth regimes. We also report that the increase in shielding due to background charges increases the growth rate of the instability. Moreover, the increase in the Atwood number, an entity to quantify the density gradient, shows the enhancement of the growth of the instability. The dispersion relation obtained from the molecular dynamics simulation of strongly coupled plasma shows a slight growth enhancement compared to the hydrodynamic viscous fluid. The RTI and its eventual impact on turbulent mixing can be significant in energy dumping mechanisms in inertial confinement fusion where, during the compressed phases, the coupling strength approaches unity.

Thermodynamic state variables in quasiequilibrium ultracold neutral plasma.

The pressure and internal energy of an ultracold plasma in a state of quasiequilibrium are evaluated using classical molecular dynamics simulations. Coulomb collapse is avoided by modeling electron-ion interactions using an attractive Coulomb potential with a repulsive core. We present a method to separate the contribution of classical bound states, which form due to recombination, from the contribution of free charges when evaluating these thermodynamic state variables. It is found that the contribution from free charges is independent of the choice of repulsive core length scale when it is sufficiently short-ranged. The partial pressure associated with the free charges is found to closely follow that of the one-component plasma model, reaching negative values at strong coupling, while the total system pressure remains positive. This pseudopotential model is also applied to Debye-Hückel theory to describe the weakly coupled regime.