Systematic Study of Fermion Masses and Mixing Angles in Horizontal SU(2) Gauge Theory

Despite its great success in explaining the basic interactions of nature, the standard model suffers from an inability to explain the observed masses of the fundamental particles and the weak mixing angles between them. We shall survey a set of possible extensions to the standard model, employing an SU(2) ``horizontal'' gauge symmetry between the particle generations, to see what light they can shed on this problem.Comment: 43 pages, 4 figures (available by postal mail on request), OZ-92/0

First record of Selene dorsalis (Gill; 1862) (Osteichthyes: Carangidae) in the Canary Islands (Central-east Atlantic)

We report the capture of a specimen of Selene dorsalis (Gill; 1862); a rare species in waters north of the Cape Verde Islands and Senegal. This is the first time that it has been recorded among the ichthyofauna of the Canary Islands.Se informa de la captura de un ejemplar de Selene dorsalis (Gill; 1862); especie rara en las aguas al norte de las islas de Cabo Verde y Senegal. Es la primera cita de esta especie para la ictiofauna de las islas Canarias.Instituto Español de Oceanografí

Using travertine deformations to characterize paleoseismic activity along an active oblique-slip fault: the Alhama de Murcia fault (Betic Cordillera, Spain)

A preliminary paleoseismic study of trave rtine deposits cut by an active oblique-slip fault is presented. The Alhama de Murcia fault affects late Pleistocene and Holocene travertine deposits along the Lorca-Totana segment. Travertines along oblique-slip (reverse-sinistral) active faults have not been reported. On the Alhama de Murcia fault, CaCO3 rich springs are linked to an extensional step-ove rand to releasing fault junctions in a reverse-sinistral fault zone. The sampling methodology for U/Th dating employed to avoid contamination (by choosing material from a geochemical closed system) is described. A petrographic analysis is necessary to ensure the quality of the samples. Terrace-mound, fissure-ridge, eroded sheets and range-front trave rtine deposits occur in the Alhama de Murcia fault zone. At Carraclaca a 15 m amplitude monocline fold was formed by the reverse movement of this fault which has been active since the late Pleistocene. The first available absolute ages for deformed and undeformed travertines yield a vertical slip rate of 0.08mm/yr. It is possible to estimate 4818 yr of recurrence time for the northern branch given the slip per event on alluvial deposits in the southern branch of the Alhama de Murcia fault

Correlation between preoperative CT scan and lung metastases according to surgical approach in patients with colorectal cancer

Introduction: The number of lung metastases (M1) of colorectal carcinoma (CRC) in relation to the findings of computed tomography (CT) is the object of study. Methods: Prospective and multicenter study of the Spanish Group for Surgery of CRC lung metastases (GECMP-CCR). The role of CT in the detection of pulmonary M1 is evaluated in 522 patients who underwent a pulmonary metastasectomy for CRC. We define M1/CT as the ratio between metastatic nodules and those found on preoperative CT. Disease-specific survival (DSS), disease-free survival (DFS), and surgical approach were analyzed using the Kaplan–Meier method. Results: 93 patients were performed by video-assisted surgery (VATS) and 429 by thoracotomy. In 90%, the M1/CT ratio was =1, with no differences between VATS and thoracotomy (94.1% vs 89.7%, p = 0.874). In the remaining 10% there were more M1s than those predicted by CT (M1/CT > 1), with no differences between approaches (8.6% vs 10%, p = 0.874). 51 patients with M1/CT > 1, showed a lower median DSS (35.4 months vs 55.8; p = 0.002) and DFS (14.2 months vs 29.3; p = 0.025) compared to 470 with M1/CT = 1. No differences were observed in DSS and DFS according to VATS or thoracotomy. Conclusions: Our study shows equivalent oncological results in the resection of M1 of CRC using VATS or thoracotomy approach. The group of patients with an M1/CT ratio >1 have a worse DSS and DFS, which may mean a more advanced disease than predicted preoperatively. Introducción El número de metástasis pulmonares (M1) de carcinoma colorrectal (CCR) en relación con los hallazgos de la tomografía computarizada (TC), es objeto de estudio. Métodos Estudio prospectivo y multicéntrico del Grupo Español de Cirugía de las metástasis pulmonares del CCR (GCMP-CCR). Se evalúa el papel de la TC en la detección de M1 pulmonares en 522 pacientes intervenidos de una metastasectomía pulmonar por CCR. Definimos como M1/CT al cociente entre los nódulos metastásicos y los hallados en la TC preoperatoria. Se analizó la supervivencia específica de enfermedad (SEE), la supervivencia libre de enfermedad (SLE) y el abordaje quirúrgico mediante el método de Kaplan-Meier. Resultados En 93 pacientes se utilizó la cirugía videoasistida (VATS) y 429 toracotomías. En un 90% el cociente M1/TC fue =1, sin diferencias entre VATS y toracotomía (94,1 vs. 89,7%; p = 0,874). En el 10% restante existían más M1 que las predichas por la TC (M1/CT > 1), sin diferencias entre abordajes (8,6 vs. 10%; p = 0,874). Cincuenta y un pacientes con M1/CT > 1, mostraron una menor mediana de SEE (35,4 vs. 55,8 meses; p = 0,002) y SLE (14,2 vs. 29,3 meses; p = 0,025) en comparación con 470 con M1/CT = 1. No se observaron diferencias en la SEE y la SLE según VATS o toracotomía. Conclusiones Nuestro estudio muestra unos resultados oncológicos equivalentes en la resección de M1 de CCR mediante abordaje VATS o toracotomía. El grupo de pacientes con un cociente M1/CT > 1 presentan una peor SEE y SLE, pudiendo significar una enfermedad más avanzada de la predicha preoperatoriamente

Control PD de Robots: Dinámica de Actuadores y Nueva Sintonía

ResumenEn el presente trabajo se estudia el control PD con compensación deseada de gravedad de robots rígidos. Se introduce un nuevo criterio, menos conservador, para seleccionar las ganancias proporcionales. Se demuestra estabilidad asintótica global cuando se toma en consideración durante el diseño la dinámica eléctrica de los motores de CD con escobillas usados como actuadores. Este resultado no requiere que la dinámica eléctrica de los actuadores sea rápida comparada con la dinámica de la parte mecánica. Se presenta un estudio formal de la técnica de control conocida como control de par la cual es ampliamente utilizada en la práctica industrial

Evidence for coseismic events of recurrent prehistoric deformation along the Alhama de Murcia fault, southeastern Spain

The Alhama de Murcia fault is a 85 km long oblique-slip fault, and is related to historical and instrumental seismic activity. A paleoseismic analysis of the Lorca-Totana sector of the fault containing MSK I=VIII historical earthquakes was made in order to identify and quantify its seismic potential. We present 1) the results of the neotectonic, structural and geomorphological analyses and, 2) the results of trenching. In the study area, the Alhama de Murcia fault forms a depressed corridor between two strands, the northwestern fault with morphological and structural features of a reverse component of slip, bounding the La Tercia range to the South, and the southeastern fault strand with evidence of sinistral oblique strike-slip movement. The offset along this latter fault trapped the sediments in transit from the La Tercia range towards the Guadalentín depression. The most recent of these sediments are arranged in three generations of alluvial fans and terraces. The first two trenches were dug in the most recent sediments across the southeastern fault strand. The results indicate a coseismic reverse fault deformation that involved the sedimentary sequence up to the intermediate alluvial fan and the Holocene terrace deposits. The sedimentary evolution observed in the trenches suggests an event of temporary damming of the Colmenar creek drainage to the South due to uplifting of the hanging wall during coseismic activation of the fault. Trench, structural and sedimentological features provide evidence of at least three coseismic events, which occurred after 125,000yr. The minimum vertical slip rate along the fault is 0.06mm/yr and the average recurrence period should not exceed 40,000yr in  accordance with the results obtained by fan topographic profiling. Further absolute dating is ongoing to constrain these estimates.

Glial alterations in human prion diseases

Background: Neuroinflammation has recently been proposed to be a major component of neurodegenerative diseases. The aim of this study was to determine how the interaction between microglia and astroglia, which are the primary immune cell populations in the brain, and pathological prion protein (PrPsc) could influence the development and propagation of this neurodegenerative disease. Because a relevant role for glial response in prion disease has been clearly demonstrated in our previous studies using the natural animal model, a similar approach has been taken here using the natural human model. Methods: A morphological approach has been developed to analyze cerebellar samples from patients with Creutzfeldt-Jakob disease (CJD) in comparison with healthy control cases. Histopathological lesions were assessed, and PrPsc, glial fibrillary acidic protein (GFAP) and reactive microglia were immunolabelled by specific antibodies. Furthermore, co-location studies using confocal microscopy were performed to determine the possible relationships between both types of glial cells in all samples. Results: The results presented in this study support the involvement of both types of glial cells in CJD. Evidence of increased astrocyte and microglia reactivity can be observed in all CJD cases, and a close relationship between the types of glia is demonstrated by co-location studies. Conclusion: Proteinopathies such as Alzheimer, Parkinson, and Huntington diseases, where aberrant proteins spread throughout the brain during disease progression, may share a molecular basis and mechanisms of propagation. Therefore, studies elucidating the interaction between gliosis and prion propagation may be relevant to these other neurodegenerative diseases and may provide new targets for therapeutic intervention

Tests of Higgs and Top Effective Interactions

We study the possibility to detect heavy physics effects in the interactions of Higgs bosons and the top quark at future colliders using the effective Lagrangian approach. The modification of the interactions may enhance the production of Higgs bosons at hadron colliders through the mechanisms of gluon fusion and associated production with a W boson or $t\bar{t}$ pairs. The most promising signature is through the decay of the Higgs boson into two photons, whose branching ratio is also enhanced in this approach. As a consequence of our analysis we get a bound on the chromomagnetic dipole moment of the top quark.Comment: 14 pages, Latex, two figures available by fax under request. To be published in Phys. Lett