Subcritical Thermal Convection of Liquid Metals in a Rapidly Rotating Sphere.

Planetary cores consist of liquid metals (low Prandtl number Pr) that convect as the core cools. Here, we study nonlinear convection in a rotating (low Ekman number Ek) planetary core using a fully 3D direct numerical simulation. Near the critical thermal forcing (Rayleigh number Ra), convection onsets as thermal Rossby waves, but as Ra increases, this state is superseded by one dominated by advection. At moderate rotation, these states (here called the weak branch and strong branch, respectively) are smoothly connected. As the planetary core rotates faster, the smooth transition is replaced by hysteresis cycles and subcriticality until the weak branch disappears entirely and the strong branch onsets in a turbulent state at Ek<10^{-6}. Here, the strong branch persists even as the thermal forcing drops well below the linear onset of convection (Ra=0.7Ra_{crit} in this study). We highlight the importance of the Reynolds stress, which is required for convection to subsist below the linear onset. In addition, the Péclet number is consistently above 10 in the strong branch. We further note the presence of a strong zonal flow that is nonetheless unimportant to the convective state. Our study suggests that, in the asymptotic regime of rapid rotation relevant for planetary interiors, thermal convection of liquid metals in a sphere onsets through a subcritical bifurcation.

Saturation of nonaxisymmetric instabilities of magnetized spherical Couette flow.

We numerically investigate the saturation of the hydromagnetic instabilities of a magnetized spherical Couette flow. Previous simulations demonstrated a region where the axisymmetric flow, calculated from a 2D simulation, was linearly unstable to nonaxisymmetric perturbations. Full, nonlinear, 3d simulations showed that the saturated state would consist only of harmonics of one azimuthal wave number, though there were bifurcations and transitions as nondimensional parameters (Re, Ha) were varied. Here, the energy transfer between different azimuthal modes is formulated as a network. This demonstrates a mechanism for the saturation of one mode and for the suppression of other unstable modes. A given mode grows by extracting energy from the axisymmetric flow, and then saturates as the energy transfer to its second harmonic equals this inflow. At the same time, this mode suppresses other unstable modes by facilitating an energy transfer to linearly stable modes.

Role of large-scale velocity fluctuations in a two-vortex kinematic dynamo.

This paper presents an analysis of the Dudley-James two-vortex flow, which inspired several laboratory-scale liquid-metal experiments, in order to better demonstrate its relation to astrophysical dynamos. A coordinate transformation splits the flow into components that are axisymmetric and nonaxisymmetric relative to the induced magnetic dipole moment. The reformulation gives the flow the same dynamo ingredients as are present in more complicated convection-driven dynamo simulations. These ingredients are currents driven by the mean flow and currents driven by correlations between fluctuations in the flow and fluctuations in the magnetic field. The simple model allows us to isolate the dynamics of the growing eigenvector and trace them back to individual three-wave couplings between the magnetic field and the flow. This simple model demonstrates the necessity of poloidal advection in sustaining the dynamo and points to the effect of large-scale flow fluctuations in exciting a dynamo magnetic field.

Reducing global turbulent resistivity by eliminating large eddies in a spherical liquid-sodium experiment.

Three-wave turbulent interactions and the role of eddy size on the turbulent electromotive force are studied in a spherical liquid-sodium dynamo experiment. A symmetric, equatorial baffle reduces the amplitude of the largest-scale turbulent eddies, which is inferred from the magnetic fluctuations spectrum (measured by a 2D array of surface probes). Differential rotation in the mean flow is >2 times more effective in generating mean toroidal magnetic fields from the applied poloidal field (via the Ω effect) when the largest-scale eddies are eliminated, thus demonstrating that the global turbulent resistivity (the ß effect from the largest-scale eddies) is reduced by a similar amount.

Familial papillary serous carcinoma of the cervix, peritoneum, and ovary: a report of the first case.

OBJECTIVE: We report an occult primary papillary serous carcinoma of the endocervix that was encountered in a woman whose mother and identical twin sister died of papillary serous carcinomas (PSCs) of the peritoneum and ovary, respectively. METHODS: The medical records and the histologic material belonging to the patient, her sister, and her mother were reviewed. RESULTS: The cervical PSC was histologically similar to the peritoneal and ovarian carcinomas. The patient has recurred with peritoneal carcinomatosis 24 months following surgery and postoperative radiotherapy and chemotherapy. CONCLUSIONS: Primary papillary serous carcinoma of the cervix is a very rare adenocarcinoma variant; there have been approximately 30 such cases reported, and, to our knowledge, this is the first documented case of familial peritoneal/ovarian/uterine papillary serous carcinoma. The prophylaxis achieved through bilateral oophorectomy in individuals with a family history of ovarian cancer does not address the risk of PSCs arising in the uterus, cervix, or peritoneum.

HIV-related primary non-Hodgkin's lymphoma of the vulva.

We reported on a 25-year-old HIV-positive woman diagnosed with Ann Arbor Stage IEB primary extranodal immunoblastic lymphoma arising in the vulva. This is the first documented instance of an HIV-associated malignant lymphoma originating in the lower female genital tract, and only the 16th reported case of primary malignant lymphoma of the vulva. The nonspecific clinical presentation coupled with the unanticipated finding of lymphoma made diagnostic confirmation an arduous task, requiring weeks of persistence. The patient's disease was refractory to three courses of chemotherapy, but did respond to a brief palliative course of external beam irradiation prior to her demise 7 months after presentation. Our findings are presented, and 15 cases from the literature, the largest series to date, are discussed.

Prostate carcinoma patients upstaged by imaging and treated with irradiation. An outcome-based analysis.

BACKGROUND: The American Joint Committee on Cancer (AJCC) staging of prostate cancer relies upon digital rectal examination (DRE) findings, but suggests using all available information, including prostate imaging studies, prior to definitive treatment of prostate carcinoma. We have studied whether patients upstaged by imaging have a different outcome after treatment with external beam radiation therapy (RT) from those not upstaged. METHODS: The records of 499 men with clinically localized adenocarcinoma of the prostate treated with only definitive external beam irradiation from January 1986 to December 1993 were reviewed. The 348 patients with any one or a combination of the following pretreatment imaging studies were considered eligible; transrectal ultrasound (TRUS), pelvic MRI, or endorectal MRI. Patients were assigned two clinical stages: one based upon palpation criteria alone (palpation stage) and the other allowing for any upstaging by imaging abnormalities (AJCC or imaging stage). The Kaplan-Meier method was used to estimate biochemical no evidence of disease (bNED) survival where a failure was defined as a prostate specific antigen (PSA) greater than 1.5 and increasing. Differences in outcome were evaluated by the log-rank test. RESULTS: Overall upstaging by TRUS or MRI to any higher stage occurred in 115 of 312 palpation T1c-T2c patients (37%). These upstaged patients had an unexpected improvement in bNED survival (84% vs. 71%, P = 0.05) compared with those who were not upstaged due to the upstaged patients having a significantly greater number with a pretreatment PSA < 10 ng/mL. T1c patients were upstaged by imaging in 81% of the 94 patients. The 36-month bNED survival of palpation T1c and imaging T2 patients was similar (88% vs. 88%, P = NS), but both were significantly improved compared with the 36-month bNED survival for palpation T2 patients (88% vs. 71%, P = 0.04). There was no significant difference in 36-month bNED survival for imaging T2c (bilobar disease) patients compared with their original palpation stage disease. Upstaging to T3 occurred in 10% of palpation T1c-T2c patients. There was no difference in 36-month bNED survival for the imaging T3 patients compared with their original palpation stage (84% vs. 71%, respectively, P = 0.04). There was a significant improvement in the 36-month bNED survival for imaging T3 patients compared with palpation T3 patients (84% vs. 50% respectively, P = 0.01). Multivariate analysis demonstrated palpation stage to be a significant predictor of bNED survival (P = 0.001), while AJCC stage (including imaging) is not predictive. CONCLUSIONS: Using the endpoint of bNED survival, upstaging by TRUS/MRI does not separate prostate cancer patients treated with RT into groups with different prognoses. Upon multivariate analysis, palpation stage alone, not AJCC stage including imaging upstaging, is a significant predictor of bNED survival.