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Search Results: 1 - 10 of 46 matches for " Algaba "
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Renal Adenomas: Pathological Differential Diagnosis with Malignant Tumors
F. Algaba
Advances in Urology , 2008, DOI: 10.1155/2008/974848
Abstract: The renal adenomas can be confused by imaging diagnosis with malignant renal tumors, but there are also real biological dilemmas to determine their behavior. The consensus decisions are the following. (1) The adenoma of clear cells is not accepted, instead it is considered that all the clear-cell tumors are carcinomas, with greater or lesser aggressiveness. (2) Among the papillary neoplasms the WHO 2004 renal cell tumors classification are considered as papillary adenomas tumors with a maximum diameter of 5 mm and may represent a continuum biological process to papillary renal cell carcinoma. The papillary adenomas associated with End-kidney and/or acquired cystic disease may have a different pathogenesis. (3) To consider a tumor as an oncocytoma the size is not important, only the cytological features, microscopic, ultrastructural, and immunohistochemically can help, but some chromosomal observations introduce some questions about its relation with the chromophobe renal cell carcinoma. (4) Finally, the metanephric adenoma, a tumor with some morphological similarity with the nephroblastoma must be considered in the renal adenomas diagnosis.
Probing Helical Magnetic Fields in AGN by Rotation Measure Gradients Studies
J. C. Algaba
Physics , 2011, DOI: 10.1142/S2010194512004758
Abstract: One of the tools that can provide evidence about the existence of helical magnetic fields in AGN is the observation of rotation measure gradients across the jet. Such observations have been previously made successfully, proving that such gradients are far from being rare, but common and typically persistent over several years, although some of them may show a reversal in the direction along the jet. Further studies of rotation measure gradients can help us in our understanding of the magnetic field properties and structure in the base of the jets. We studied Very Long Baseline Array (VLBA) polarimetric observations of 8 sources consistent of some quasars and BL Lacs at 12, 15, 22, 24 and 43 GHz and we find that all but two sources show indications of rotation measure gradients, either parallel or perpendicular to the jet. We interpret gradients perpendicular to the jet as indications of the change of the line of sight of the magnetic field due to its helicity, and gradients parallel to the jet as the decrease of magnetic field strength and/or electron density as we move along the jet. When comparing our results with the literature, we find tentative evidence of a rotation measure gradient flip, which can be explained as a change of the pitch angle or jet bending.
High Frequency VLBI Rotation Measure of 8 AGN
J. C. Algaba
Physics , 2012, DOI: 10.1093/mnras/sts624
Abstract: We have studied Very Long Baseline Array (VLBA) polarimetric observations of 8 sources including quasars and BL Lacs at 12, 15, 22, 24 and 43 GHz and high frequency rotation measure ($RM$) maps are presented. We find typical values for the $RM$ in the VLBI core of several thousand rad/m$^2$, which are higher than values in the literature at lower frequencies. Assuming a dependence of the form $RM\propto \nu^a$, we obtain an average value of $a=3.6\pm1.3$, which is larger than that expected by theoretical considerations. Rotation measures are detected in the jet of only two sources and we find that only 0906+430 (and possibly 1633+382) show indications of a robust gradient. We discuss the Faraday--corrected polarization properties of the sources. Our interpretation supports the presence of helical magnetic fields with new, unresolved, components affecting the intrinsic direction of polarization close to the base of the jet of some objects.
Management of Small Renal Masses
Jose Rubio Briones,F. Algaba
Advances in Urology , 2008, DOI: 10.1155/2008/606401
Abstract:
Helical magnetic fields in the M87 jet at arc-second scales
J. C. Algaba,K. Asada,M. Nakamura
Physics , 2013,
Abstract: We investigate the magnetic field configuration of the M87 jet at arc-second scales by using archival polarimetric VLA data at 8, 15, 22 and 43 GHz. By stacking images over three years in order to enhance the sensitivity, we reveal, for the first time, systematic transverse gradients of the Faraday rotation measure in several knots along the jet. Combining this result with polarization properties and the dynamics of the jet, we suggest the magnetic structure in several knots at kiloparsec scales consists of a systematically wrapped, tightly wound helical configuration. Our analysis brings us a new paradigm where the M87 jet is a fundamentally current carrying system produced in the vicinity of the supermassive black hole, transferring a huge amount of the electromagnetic energy over the host galaxy scale.
Infarto testicular segmentario: un pseudotumor infrecuente
Arce Terroba,Y.; Algaba-Arrea,F.; Villavicencio Maverich,H.;
Actas Urológicas Espa?olas , 2010, DOI: 10.4321/S0210-48062010000200012
Abstract: objective: to review the morphologic features of the segmental infarct of testicle with special insistence in the differential diagnosis with a testicular tumor. material and methods: retrospective revision of the cases with pathologic diagnostic of segmental infarct of testicle diagnosed and treated in our institution. in the selected cases, we review the histological slides and we collected the clinical and radiological features. results: we reported 6 cases with the following clinic-pathological features: the average age was 42 years old, both right and left testicles were affected with the same frequency, and the aetiology was idiopathic, trauma or inflammation. all of them with pathological diagnosis of segmental infarct of testicle, either acute or chronic, and in all of them a testicular tumor was suspected. conclusion: segmental infarct of testicle is an unfrequent cause of testicular pseudotumor. it must be considered in the clinical differential diagnostic of testicular masses in order to avoid unnecessary orchiectomies.
Carcinoma mixto de urotelio y célula peque?a de vejiga urinaria: metástasis de la histología neuroendocrina sola: Comunicación del caso y revisión de la literatura
Capdevila,Jaume; Maroto,Pablo; Algaba,Ferran; Lerma,Enrique; Villavicencio,Humberto;
Archivos Espa?oles de Urología (Ed. impresa) , 2007, DOI: 10.4321/S0004-06142007000300016
Abstract: objective: to report one case of transitional cell carcinoma with areas of small cell carcinoma presenting in its evolution an adrenal metastasis with the neuroendocrine component only. we perform a bibliography review for the cases of small cell carcinoma of the bladder, its epidemiology, prognosis and treatment. methods: we describe the clinical case and perform a medline review. results: small cell carcinoma of the bladder is a rare entity, with a more aggressive behaviour and poorer prognosis than transitional cell carcinoma. the pathologic characteristics allow differentiation of primary tumor and metastatic disease. in the bibliographic search we did not find any previous report of exclusive dissemination of the neuroendocrine histological component in cases of mixed tumors. conclusions: there is no standard treatment for small cell carcinoma of the bladder. for metastatic disease the most commonly used combination is cisplatin and etoposide.
On the Formal Integrability Problem for Planar Differential Systems
Antonio Algaba,Cristóbal García,Jaume Giné
Abstract and Applied Analysis , 2013, DOI: 10.1155/2013/482305
Abstract:
Corrosión de armaduras embebidas en hormigón carbonatado
Andrade, C.,Algaba, S.,González, J. A.
Materiales de Construccion , 1981,
Abstract: Not available Los componentes ácidos de la atmósfera, en particular el CO2, pueden neutralizar (carbonatar) el electrólito que llena los poros del hormigón y las fases del clínker, transformándolos en variedades del CO3Ca. La carbonatación no sólo modifica la estructura de la pasta de cemento y por lo tanto sus propiedades, sino que también tiene una influencia decisiva sobre la velocidad de corrosión de las armaduras (1) (2). En un reciente informe del Comité 12-CRC de la RILEM (3) se afirmaba que: "si se exceptúa la corrosión causada por Cl-, actualmente se está de acuerdo en que la carbonatación del hormigón es la condición esencial para la corrosión de las armaduras". (Aquí se debería a adir que esto se aplica a los hormigones simplemente armados, pues en los pretensados también es muy peligroso el fenómeno conocido como corrosión bajo tensión). La carbonatación puede desencadenar el proceso de corrosión, debido a que el descenso de pH que provoca hace posible el paso de las armaduras del estado pasivo al activo. La velocidad de ataque depende, sin embargo, de otros factores externos: un contenido mínimo de humedad en el medio ambiente que garantice la existencia del electrólito en los poros del hormigón, y un libre acceso de O2 hasta la superficie metálica para que pueda producirse la semirreacción catódica. Numerosos autores están de acuerdo con estos puntos, pero sin aportar pruebas cuantitativas de los mismos. Es objeto principal de este trabajo contribuir a llenar este vacío.
Hints of High Core Faraday Rotations from a Joint Analysis of VLBA and Optical Polarization Data
J. C. Algaba,D. C. Gabuzda,P. S. Smith
Physics , 2009,
Abstract: Although the continua of radio-loud Active Galactic Nuclei (AGN) are typically dominated by synchrotron radiation over virtually the entire spectrum, it is not clear whether the radio and higher-frequency emission originate in the same or different parts of the jet. Several different radio--optical correlations based on polarization data have been found recently, suggesting that the optical and radio polarization may be closely related, and that the corresponding emission regions may be cospatial (Gabuzda et. al2006, Jorstad et al. 2007, D'Arcangelo et al. 2007) Our joint analysis of optical and VLBA polarization data for a sample of about 40 AGNs shows that, after correction for the inferred VLBA core Faraday rotations, most BL Lac objects and some quasars have aligned VLBA-core and optical polarizations, although many quasars also show no obvious relationship between their VLBA-core and optical polarization angles. This may indicate that not all AGNs have cospatial regions of optical and radio emission in their jets. However, another possibility is that some of the 7mm-2cm VLBA cores have Faraday rotations of the order of several tens of thousand of rad/m^2, which were not properly fit by our three-frequency data due to n*pi ambiguities in the observed polarization angles, leading to incorrect subtraction of the effects of the core Faraday rotation, and so incorrect "zero-wavelength" radio polarization angles. The possibility of such high core Faraday rotations is supported by the results of the parsec-scale Faraday-rotation studies of Zavala & Taylor (2004) and Jorstad et al. (2007).
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