On forced coastal trapped waves at low latitudes in a stratified ocean

The response on the continental shelf and slope of a baroclinic ocean to driving by an alongshore wind stress at the coast

Central equatorial Pacific zonal currents. I: The Sverdrup balance, nonlinearity and tropical instability waves. Annual mean dynamics

Several recent observational studies of central Pacific equatorial current dynamics have suggested that, in the vertical integral between the surface and the thermocline, the linear equatorial Sverdrup balance holds. However, in a high vertical resolution ocean general circulation model, we find that nonlinearity is an order (1) element of the local and the vertically integrated balances on and near the equator at 140W. Although this OGCM has been used in many studies of the tropical Pacific, its equatorial zonal momentum equation balances have never been described in detail and compared with observations. We describe the annual mean balances here, identify the similarities and differences between the model balances and observational estimates of the balances, and discuss various reasons why the model and the observations may disagree in the respects that they are found to do so. The term balances vary strongly with latitude and depth; the system is nonlinear and three dimensional. There is little tendency for pairs of terms (e.g., the meridional and vertical advection terms) to balance locally or in the vertical integral. Every term in the zonal momentum equation plays a role somewhere in the analysis region discussed here. Thus the generality of point estimates of these balances is small. The Tropical Instability Wave zonal momentum flux divergence, although not an O (1) term in the balance, acts like a \u27negative viscosity\u27 over the upper 40 m on the equator; its tendency is to drive westward flow. If the ocean balances resemble those of the model dynamics, gaining detailed perspective on the zonal balances will require a major observational effort. Because there is strong subseasonal and interannual variability of the flows in the central equatorial Pacific, time-mean balances are not simple to estimate. Further, special attention will have to be given to resolving the shears in the upper 50 m, because it is over these depths that the model and observational results differ most strongly. We suggest that the widely used technique of extrapolating the near-surface currents based on their shears in the uppermost bins of the ADCP profiles deserves careful scrutiny; subsampling the model flow profiles in this fashion leads to important errors. Until the strong vertically sheared very near-surface current field is observed accurately it will not be possible to determine if the model results are correct, but we suggest that the existing observational results should not be regarded as definitive

Central equatorial Pacific zonal currents. II: The seasonal cycle and the boreal spring surface eastward surge

The seasonally averaged zonal momentum equation tendencies at 140W are studied in a high-resolution primitive equation ocean general circulation model simulation of the tropical Pacific. The model experiment, forced by climatological monthly average wind-stress, reproduces well the observed boreal springtime eastward surge of the normally westward surface flow, as well as many features of the acceleration and deceleration between the surface and 200 m between January and October. We present each of the zonal momentum equation tendency terms for the depth range 0-160 m, but our discussion focuses on the behavior of the boreal springtime near-surface flow, perhaps the most distinctive feature of the seasonal cycle. The eastward surface surge in boreal spring depends crucially on the springtime weakening of the otherwise westward tendency from tropical instability waves (TIWs). The TIW effects, together with the eastward tendency from the seasonal weakening of the easterly wind-stress, drive the eastward surface current surge. Although the \u27negative viscosity\u27 effect of the TIWs is small in the annual mean, as we have previously shown, its seasonal variation is necessary to the surface flow reversal and eastward surge in this model. A series of experiments, each with weaker TIWs than its predecessor, shows a progressive weakening and eventual absence of springtime eastward surface flow, supporting the above analysis. The seasonal zonal velocity accelerations and decelerations are small compared with the terms in the zonal momentum equation; these terms must be known to an accuracy of at least 10 cm s-1 month-1 (2-5% of the largest terms) if a meaningful budget is to be obtained. This is a strong constraint that must be planned for in future observational studies. We find that nonlinear terms are O (1) in the vertically-integrated balance as well as the local balance, in contrast with some recent observational estimates. Extrapolated velocity errors, neglected terms, data processing assumptions, and crude finite-differencing in the observational studies may account for the differences, as appeared to be the case in the annual mean balances. The model dynamical balances cannot be reproduced if the methods used to analyze observational data are applied to the model output fields. Very near-surface currents must be measured rather than extrapolated if the ocean shear is similar to that of the model flows

Mastectomía contralateral profiláctica con reconstrucción inmediata en pacientes con cáncer de mama unilateral sin mutación germinal en BRCA1/2

Introducción No existe un consenso sobre las indicaciones de mastectomía contralateral en pacientes diagnosticadas de cáncer de mama unilateral sin mutación germinal en BRCA1/2. Estudios previos han identificado algunos factores que pueden influir en la toma de la decisión dependientes del tumor, como el tamaño o histología, de la paciente, como la edad, y de la cirugía como la posibilidad de realizar una reconstrucción inmediata o la experiencia del cirujano. Métodos Estudio retrospectivo de una cohorte de 176 pacientes diagnosticadas de CM entre 2010 y 2016 a las que se les realizó cirugía mamaria. Se ha analizado la asociación de características del tumor y de la paciente con la toma de decisión de realizar mastectomía contralateral (MC) o no-MC. Asimismo, se han analizado los datos relacionados con la cirugía y la recurrencia por grupos mediante la curva de incidencia acumulada y el test de Gray. Resultados El número de MC se ha incrementado en nuestro centro. No hemos encontrado diferencias significativas en el desarrollo de complicaciones posquirúrgicas entre los 2 grupos de pacientes, pero sí en la estancia hospitalaria, siendo superior para MC. También hemos observado diferencias entre ambas cohortes en edad y tipo de tumor, siendo la MC más frecuente en aquellas pacientes más jóvenes y subtipo luminal A. Hemos hallado diferencias en la incidencia acumulada de recidiva entre ambos subgrupos (p = 0, 034). Conclusiones En nuestra cohorte la MC se realiza más frecuentemente en pacientes más jóvenes y con cáncer de mama luminal A. Introduction: There is no consensus on the indications for contralateral mastectomy (CM) in patients diagnosed with unilateral breast cancer without germline BRCA1/2 mutations. Prior studies have identified some factors that could influence decision-making. These factors include tumoural size and histological type; patient-related factors, such as age; and surgical factors such as the possibility of immediate reconstruction and the surgeon''s experience. Methods: Retrospective study of a cohort of 176 patients diagnosed with breast cancer between 2010 and 2016 who underwent breast surgery. We analysed the association between tumoural and patient-related characteristics with the decision to perform CM or not. We also analysed data related to surgery and recurrence by groups by using the cumulative incidence curve and the Gray test. Results: The number of CM has increased in our centre. We found no significant differences in the occurrence of post-surgical complications between the two patient groups but length of hospital stay was higher in CM. We also found differences between the two cohorts in age and tumoural type, with CM being more frequent in younger patients and those with luminal A subtype. Differences were found in the cumulative incidence of recurrence between subgroups (p = 0.034). Conclusions: In our cohort, CM was more frequent in younger patients and in those with luminal A breast cancer