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The main auroral emission at Jupiter generally appears as a quasi-closed curtain centered around the magnetic pole. This auroral feature, which accounts for approximately half of the total power emitted by the aurorae in the ultraviolet range, is related to corotation enforcement currents in the middle magnetosphere. Early models for these currents assumed axisymmetry, but significant local time variability is obvious on any image of the Jovian aurorae. Here we use far-UV images from the Hubble Space Telescope to further characterize these variations on a statistical basis. We show that the dusk side sector is ~ 3 times brighter than the dawn side in the southern hemisphere and ~ 1.1 brighter in the northern hemisphere, where the magnetic anomaly complicates the interpretation of the measurements. We suggest that such an asymmetry between the dawn and the dusk sectors could be the result of a partial ring current in the nightside magnetosphere.

The aurorae at Jupiter are made up of many different features associated with a variety of generation mechanisms. The main auroral emission, also known as the main oval, is the most prominent of them as it accounts for approximately half of the total power emitted by the aurorae in the ultraviolet range. The energy of the precipitating electrons is a crucial parameter to characterize the processes at play which give rise to these auroral emissions, and the altitude of the emissions directly depends on this energy. Here we make use of far-UV (FUV) images acquired with the Advanced Camera for Surveys on board the Hubble Space Telescope and spectra acquired with the Space Telescope Imaging Spectrograph to measure the vertical profile of the main emissions. The altitude of the brightness peak as seen above the limb is ~ 400 km, which is significantly higher than the 250 km measured in the post-dusk sector by Galileo in the visible domain. However, a detailed analysis of the effect of hydrocarbon absorption, including both simulations and FUV spectral observations, indicates that FUV apparent vertical profiles should be considered with caution, as these observations are not incompatible with an emission peak located at 250 km. The analysis also calls for spectral observations to be carried out with an optimized geometry in order to remove observational ambiguities.

We have investigated statistically the electron density below 5 cm−3 in the magnetosphere of Saturn (7–80 RS, Saturn radii) using 44 orbits of the floating potential data from the RPWS Langmuir probe (LP) onboard Cassini. The density distribution shows a clear dependence on the distance from the Saturnian rotation axis (√X2+Y2) as well as on the distance from the equatorial plane (|Z|), indicating a disc-like structure. From the characteristics of the density distribution, we have identified three regions: the extension of the plasma disc, the magnetodisc region, and the lobe regions. The plasma disc region is at LL is the radial distance to the equatorial crossing of the dipole magnetic field line, and confined to |Z|RS. The magnetodisc is located beyond L=15, and its density has a large variability. The variability has quasi-periodic characteristics with a periodicity corresponding to the planetary rotation. For Z>15 RS, the magnetospheric density distribution becomes constant in Z. However, the density still varies quasi-periodically with the planetary rotation also in this region. In fact, the quasi-periodic variation has been observed all over the magnetosphere beyond L=15. The region above Z=15 RS is identified as the lobe region. We also found that the magnetosphere can occasionally move latitudinally under the control of the density in the magnetosphere and the solar wind. From the empirical distributions of the electron densities obtained in this study, we have constructed an electron density model of the Saturnian nightside magnetosphere beyond 7 RS. The obtained model can well reproduce the observed density distribution, and can thus be useful for magnetospheric modelling studies.

The ion pick‐up near the icy Galilean satellites is studied using ion cyclotron waves. Using Galileo magnetometer data, we show evidence for the existence of ion cyclotron waves, which are generated by pick‐up of freshly ionized particles. Near Europa, in the wake various kinds of ions are detected, which were already predicted to be present on the moon. Upstream of the moon there is evidence for water ion pick‐up, which could facilitate the slow down of the plasma flow. Ganymede shows evidence for either water or oxygen pick up on the flanks of the magnetosphere. Callisto shows indication of hydrogen pick‐up from its atmosphere.

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According to recently published data, prophylactic mastectomy (PM) appears to prevent about 90% of the expected malignant neoplasms in women with a family history of breast cancer.To identify the frequency of high-risk lesions in PM specimens and to determine occurrence of any new primary breast cancer following PM.We performed a retrospective study of women undergoing unilateral or bilateral PM. Medical charts and pathologic findings of 35 patients who underwent bilateral mastectomies at University Hospital, Syracuse, NY, from 1989 to 1996 were reviewed. Patients with biopsy-proven bilateral breast cancer were excluded. Patients were divided into 3 groups: (A) positive family history and no known breast cancer (n = 9), (B) positive family history and contralateral neoplasia (n = 13), and (C) negative family history and contralateral neoplasia (n = 13). These findings were compared with those found in reduction mammoplasty specimens from 10 women at standard risk of breast cancer.The mean age of the control group of women undergoing reduction mammoplasty was 38 years. The pathologic specimens demonstrated no significant pathologic findings in 9 and fibrocystic change in 1. In group A, the mean number of affected relatives was 3.1, and the mean age was 38 years. Two of these 9 women had atypical duct hyperplasia and 1 had atypical lobular hyperplasia in their breasts (ie, 33% with high-risk pathologic findings). Of the 13 group B women (mean age, 46.6 years; mean of 2.5 affected relatives and unilateral breast cancer), the contralateral PM specimen contained duct carcinoma in situ in one and invasive ductal cancer in a second (15% with occult malignant neoplasms). In 13 group C patients (mean age, 47.1 years), 3 (23.1%) of the contralateral PM specimens displayed atypical duct hyperplasia or atypical lobular hyperplasia. At a mean follow-up of 4.8 years, there have been no new breast malignant neoplasms in these 45 women.The occurrence of unilateral cancer in patients with family history of breast cancer is associated with a 15.4% probability of simultaneous occult malignant neoplasms in the contralateral breast. Patients with a strong family history but no evidence of breast cancer have a substantially similar rate of proliferative disease in their PM specimens as those women who have unilateral cancer but no significant family history.

Papillary thyroid carcinoma with nodular fasciitis-like stroma is one of the rare variants of papillary thyroid carcinoma. The problems posed by the exuberant nodular fasciitis-like stroma, which obscures the neoplastic nature of the tumor, are recognized in surgical pathology but have received little attention in the cytopathology literature. We report a rare case of papillary thyroid carcinoma in which nodular fasciitis-like stroma posed difficulty on fine-needle aspiration cytology. The differential diagnosis of fibroproliferative processes in thyroid fine-needle aspirations is also discussed.

To compare the immunohistochemical expression of Bcl-2 in uterine leiomyomas in patients undergoing myomectomy or hysterectomy with and without preoperative treatment with the gonadotropin-releasing hormone receptor agonist (GnRH-a) leuprolide acetate (LA).Retrospective case-control study. Seventeen patients with symptomatic uterine leiomyomata were included. Of the 17 patients, 7 were treated with LA (3.75 mg) in three monthly doses prior to myomectomy or hysterectomy. Ten patients who did not receive LA and underwent hysterectomy for leiomyomas served as controls. Formalin-fixed, paraffin-embedded archival tissue from 17 leiomyomas were immunostained with a monoclonal antibody against Bcl-2 protein. Positivity was scored semiquantitatively on a three-tier scale.Immunostaining for Bcl-2 protein was intense (2-3+) in 7 LA-treated and 10 untreated leiomyomas but was scarce (0-1+) in normal myometrial smooth muscle.Abundant expression of Bcl-2 protein may be responsible for the growth of leiomyomas by preventing apoptotic cell death. Its increased expression is maintained in GnRH-a-treated leiomyomas.

Renal cell carcinoma (RCC) arising in acquired cystic kidney disease (ACKD) is considered to be a tumor of low malignant potential, compared with classic RCC. The aim of the present study was to identify any significant differences in the antigenic profiles or tumor cell proliferative activity of ACKD-associated RCC and classic RCC that might be responsible for differences in their biologic behavior. We studied the immunohistochemical profiles and proliferative activity of 12 classic RCCs and 5 ACKD-associated RCCs with markers of proximal tubules (Leu M1, alpha-1 antitrypsin, CAM 5.2), markers of distal tubules (Arachis hypogaea lectin, AE1/AE3, epithelial membrane antigen [EMAJ, CAM 5.2), vimentin, and proliferating cell nuclear antigen (PCNA). We performed proliferation analysis with the CAS 200 image analysis system. For each case, 8 to 20 fields of tumor tissue in the areas of maximal PCNA staining were quantitated, and the percentage of PCNA-positive nuclear area for each individual tumor was calculated. All of the five ACKD-associated RCCs expressed AE1/AE3, EMA, and CAM 5.2 in more than 50% of the tumor cells. Arachis hypogaea lectin was significantly expressed in three of the five ACKD-associated RCCs. Leu M1 and alpha-1 antitrypsin reacted with fewer than 10% of the tumor cells in all of the five ACKD-associated RCCs. In contrast, the 12 classic RCCs showed expression of CAM 5.2 in 11 cases, alpha-1 antitrypsin in 10 cases, Leu M1 in 9, EMA in 8, and AE1/AE3 in 3 cases in more than 50% of the tumor cells and a totally negative reaction with Arachis hypogaea lectin in 8 cases, EMA in 4, AE1/AE3 in 4, and vimentin in 5 cases. Although coexpression of proximal and distal tubule markers was seen in some cases of RCC in either category, there was uniform and strong staining for distal tubule markers in ACKD-associated RCC and for proximal tubule markers in classic RCC. The mean percentage of PCNA-positive nuclear area for the ACKD-associated RCCs (2.41%) was significantly (P.05) less than that of the classic RCCs (21.42%). The differences in expression of proximal and distal tubule markers and proliferative activity might be responsible for the differences in the biologic behavior of ACKD-associated RCC and classic RCC.

Malignant lymphomas and solid tumors that mimic or are associated with epithelioid granulomas are widely recognized in surgical pathology, but have received little attention in the cytopathology literature. In this study the authors present their experience with six such cases in which the presence of granulomas or granuloma-like features posed a diagnostic difficulty on fine-needle aspiration cytology (FNAC).Clinical data, FNAC, and follow-up surgical specimens from six patients presenting with neck masses were reviewed.Only one case was diagnosed confidently as metastatic squamous cell carcinoma with an extensive granulomatous response; the other five were interpreted as "atypical" with descriptive cytology and a differential diagnoses including granulomatous inflammation, in addition to a caveat of "cannot exclude malignancy." Biopsy studies in these cases were recommended in view of the atypical cytologic findings and strong clinical suspicion of malignancy in each case. The histologic findings in two cases revealed Hodgkin's disease with exuberant granulomatous response. The remaining three cases were found to be malignant neoplasms with epithelioid morphologic features and included one example each of diffuse large cell lymphoma, anaplastic carcinoma of the thyroid, and lymphoepithelial carcinoma.Malignancies associated with granulomas and tumor cells mimicking epithelioid histiocytes may be difficult to diagnose accurately on FNAC. The cytologic differential diagnosis of a "granulomatous" process should include malignant neoplasms. Excisional biopsy studies may be required for definitive diagnosis.

Salivary duct carcinoma (SDC) is a highly aggressive primary salivary gland neoplasm that resembles intraductal and infiltrating breast carcinoma histologically. The purpose of this study was to review the cytologic features of histologically proven salivary duct carcinomas and to identify the potential pitfalls in cytologic diagnosis.Fine-needle aspiration cytology of nine histologically proven salivary duct carcinomas was reviewed.The patients' age ranged from 62 to 89 years (median, 69 years). There were eight males and one female. The cytologic diagnoses of these cases were as follows: pleomorphic adenoma (PA) (three cases), high grade carcinoma, not otherwise specified (three cases), mucoepidermoid carcinoma (MEC) (two cases), and atypical cytology with differential diagnosis including MEC, oncocytoma, and acinic cell carcinoma (one case). The spectrum of cytologic findings included broad flat sheets and three-dimensional clusters. There was mild to severe cellular pleomorphism and nuclear atypia. Papillary clusters and cribriforming occasionally were identified. Bland cytologic features and prominent hyaline stroma, shown to represent the dense fibrosis on histologic sections, were identified in three cases cytologically interpreted as PA.Fine-needle aspiration of SDC may be difficult to interpret accurately, and bland cytomorphologic features in some cases may lead to a false-negative interpretation; several clinically important pitfalls are demonstrated in our series.

We describe an unusual case of a basaloid squamous-cell carcinoma (BSCC) of the tonsil in a 56-yr-old man that metastasized to a primary renal-cell carcinoma (RCC) and the lung. The diagnosis of the second primary, the RCC, was based on fine-needle aspiration (FNA) cytology. A subsequent nephrectomy specimen revealed BSCC metastatic to RCC, clear-cell type. Retrospective analysis of the FNA of the renal mass revealed classic RCC morphology and, in addition, another cytologically distinctive pattern characterized by occasional sheets of cohesive neoplastic cells with hyperchromatic nuclei and nuclear molding representative of BSCC. The cytologic features of a subsequent FNA of the lung were characteristic of metastatic BSCC. Our retrospective analysis of cytologic material from the renal mass underscores the importance of raising the possibility of tumor-to-tumor metastasis when distinctly different morphologic features are seen in an otherwise typical cytology of a neoplasm in patients with an already known or suspected second primary. To our knowledge, this case report is the first one documenting metastasis of BSCC to RCC.

Invasive micropapillary carcinoma is a recently described variant of invasive breast cancer characterized by the formation of micropapillae within clear spaces separated by a fibrocollagenous stroma. Although the histologic features are well described, to the best of our knowledge, the cytologic findings have not been reported.The fine needle aspiration cytology of two cases of biopsy confirmed invasive micropapillary carcinoma are described and compared to the histologic features. In one case, an additional FNA of a subsequent metastasis is reviewed.The cytologic features of invasive micropapillary carcinoma are distinctive and correlate with the histology. Invasive micropapillary carcinoma can be suggested based on the FNA findings of numerous well-formed angular, papillary clusters along with other criteria of malignancy. The cytologic differential diagnosis of invasive micropapillary carcinoma is discussed.

We describe a rare case of a neuroendocrine carcinoma of the ovary in a 22-year-old woman who presented with abdominal pain and a pelvic mass. Exploratory laparotomy revealed a right ovarian tumor weighing 2100 g. A right salpingo-oophorectomy and an appendectomy were performed. There was no evidence intraoperatively or postoperatively of metastatic disease. Microscopic examination of the ovary revealed solid nests of tumor cells with a neuroendocrine appearance, high mitotic rate, necrosis, and vascular invasion; the tumor was associated with a predominantly borderline mucinous neoplasm with a small focus of mucinous carcinoma. Neuroendocrine differentiation was confirmed by Grimelius stains, immunohistochemical assays (chromogranin), and electron microscopy. The appendix was histologically unremarkable. The patient received a course of chemotherapy; 3 months after completing chemotherapy, she developed multiple liver metastases and died of disease a week later. To our knowledge, this case report is the second one involving a primary neuroendocrine carcinoma of the ovary occurring in association with a mucinous neoplasm. Mixed mucinous and neuroendocrine carcinoma of the ovary may represent a rare neoplasm with extremely aggressive behavior.

The primary control of autophagically mediated proteolysis in perfused rat liver is carried out via two alternate mechanisms in response to specific regulatory amino acids. One (L) elicits direct inhibition at low and high plasma levels, but requires a co-regulatory amino acid to express inhibition at normal concentrations. The second (H) is ineffective at normal levels and below, but active at higher concentrations. Because regulation is subject to unpredictable variability with ad libitum feeding, we have utilized rats synchronously fed 4 h day-1 to stabilize responses. Proteolytic control is seen to evolve in stages: H appears 12 h after the start of feeding; by 18 h L emerges, alternating with H in a statistically predictable way; with omission of the 24-h feeding, H disappears and L remains constant through 42 h. In both 18- and 42-h rats, alanine, glutamate, and aspartate exhibit similar inhibitory activity when added singly to the regulatory group at normal plasma concentrations. However, since alanine, but not glutamate or aspartate, evokes proteolytic acceleration when it is deleted from a full plasma mixture, alanine appears to be the sole co-regulator. Alanine yields co-regulatory effects with normal plasma leucine (0.2 mM) in 18- and 42-h animals and interacts synergistically with 0.8 mM leucine in 42-h but not in 18-h rats where leucine alone inhibits strongly. Because the inactivation of alanine amino-transferase by aminooxyacetate (determined from the conversion of [14C]alanine to glucose) does not alter the co-regulatory and synergistic effects of alanine, regulation by alanine must be mediated from a site of recognition before transamination.

The elegance and ease with which the Fourier transformation method can be employed in the interpretation of potential field geophysical data (Dean, 1958; Gudmundsson, 1966) has resulted in the formulation of a number of frequency‐domain approaches for interpreting the magnetic effects of specific source geometries, e.g., Bhattacharyya (1966), Sengupta (1974), Sengupta and Das (1975), Bhattacharyya and Leu (1975, 1977), etc. In these techniques, the parameters of interest are estimated from the characteristics of the amplitude and phase spectra, a process that is often beset with several problems which adversely affect the estimation of parameters. These problems arise partly from the ill‐defined nature of characteristic points in the spectra, either due to spectral noise or due to inadequate digitization spacing, and partly from the fact that the errors in the estimation of certain parameters which are used for subsequent estimation of the other parameters usually cause added spectral distortions. Rao et al. (1978) advocated the use of end corrections to overcome these problems. An effective alternative would be to incorporate the least‐squares method in the interpretational process. This necessitates iteration owing to the nonlinear nature of equations relating the source parameters and the Fourier spectra of corresponding anomalies. While it is tempting to employ the iteration scheme formulated by Gauss in 1821 for this purpose, as has indeed been done in a number of space‐domain approaches (e.g., Hall, 1958; Bosum, 1968; Al‐Chalabi, 1970; Rao et al., 1973; Won, 1981), the convergence in this approach requires the initially assumed values of the parameters to be very close to the final solution. The steepest descent method, an alternative to this, has an extremely slow convergence. It is shown here, with the example of a two‐dimensional (2-D) structure, that Marquardt’s algorithm (Marquardt, 1963), which offers a compromise between these two iteration schemes and has been effectively employed by Johnson (1969) and Pedersen (1977) in their space‐domain interpretation schemes, provides an efficient approach to accomplish the iteration in the case of frequency‐domain magnetic interpretation.