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Tumors of low malignant potential (LMP) represent 20% of epithelial ovarian cancers (EOCs) and are associated with a better prognosis than the invasive tumors (TOV). Defining the relationship between LMPs and TOVs remains an important goal towards understanding the molecular pathways that contribute to prognosis, as well as providing molecular markers, for these EOCs. To this end, DNA microarray analyses were performed either in a primary culture or a tumor tissue model system and selected candidate genes showing a distinctive expression profile between LMPs and TOVs were identified using a class prediction approach based on three statistical methods of analysis. Both model systems appear relevant as candidate genes identified by either model allowed the proper reclassification of samples as either LMPs or TOVs. Selected candidate genes (CAS, CCNE1, LGALS8, ITGb3, ATP1B1, FLIP, KRT7 and KRT19) were validated by real-time quantitative PCR analysis and show differential expression between LMPs and TOVs. Immunohistochemistry analyses showed that the two tumor classes were distinguishable by their expression of CAS, TNFR1A, FLIP, CKS1 and CCNE1. These results define signature patterns for gene expression of LMPs and TOVs and identify gene candidates that warrant further study to deepen our understanding of the biology of EOC.

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A two-dimensional model of the high-voltage breakdown has been developed, consisting of the Poisson equation and the conservation equations for electrons, ions, and excited particles. The model is based on the assumption of a low degree of ionization, so that the transport coefficients of the gas are uniquely determined by the local electric field, i.e., the model is limited to the initial stages of the channel formation. It is applied to a short plane-parallel gap in He at atmospheric pressure. The discharge is started by releasing the cloud of electrons near the cathode, and its sequence is followed up to 1.11 μs. Cathode emission is taken to include that due to ion and metastable impact and the photoeffect. The discharge develops from the initial Townsend-type discharge governed by cathode emission and the direct and Penning volume ionization, and progresses to the space-charge dominated stage. At the moment when the calculations are terminated, the maximum densities have already attained values of 1.6×1010, 2.5×1011, and 1.8×1012 cm−3 for the electrons, ions, and excited particles, respectively. The maximum axial component of the space-charge electric field is approximately 3.3 kV cm−1.

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A description and analysis of the solution of a two-dimensional model for a HV breakdown of a short gap is presented. The model consists of the electron, ion, and excited-atom conservation and Poisson equations and is applied to a plane-parallel gap with an electrode separation of 0.48 mm in helium gas at atmospheric pressure and a temperature of 293 K subjected to an electrical field of 10 kV cm−1. Two-dimensional plots of the charged and excited-particle densities and electric field components are presented and discussed. It is shown that in the first, diffusion-controlled, stage density profiles are close to a Gaussian distribution with an effective radius increasing in time. The subsequent stage is controlled by the space-charge field, causing prominent constriction of the electron density channel. In consequence, a high ionization near the discharge axis results in a virtual narrowing of the ion and excited-atom profiles as well, and the forming conductive chanel exhibits a tendency towards constriction. Calculations were conducted up to a maximum time of t=1139 ns, when maximum electron, ion, and excited-atom densities reached values of 3.1×1010, 3.7×1011, and 2.5×1012 cm−3. Among the ionization processes the direct and Penning interactions are dominant, accounting at average for approximately 70% and 30% of the total at time t=1139 ns; ionization frequencies are substantially affected by space-charge field and vary considerably in time and space near the end of calculations.

A two-dimensional model of the short gap breakdown in He has been developed consisting of conservation equations for electrons, ions and metastable atoms and the Poisson equation. Direct stepwise and Penning ionisation are considered and cathode emission takes into account the ion and metastable impact as well as photo-emission. Time development is followed up to 1.11 mu s, when the electron, ion and metastable densities reach maximum values of 1.6, 25 and 180 (*1010 cm-3) respectively.