Effects of tidal-forcing variations on tidal properties along a narrow convergent estuary

A 1D analytical framework is implemented in a narrow convergent estuary that is 78 km in length (the Guadiana, Southern Iberia) to evaluate the tidal dynamics along the channel, including the effects of neap-spring amplitude variations at the mouth. The close match between the observations (damping from the mouth to ∼ 30 km, shoaling upstream) and outputs from semi-closed channel solutions indicates that the M2 tide is reflected at the estuary head. The model is used to determine the contribution of reflection to the dynamics of the propagating wave. This contribution is mainly confined to the upper one third of the estuary. The relatively constant mean wave height along the channel (< 10% variations) partly results from reflection effects that also modify significantly the wave celerity and the phase difference between tidal velocity and elevation (contradicting the definition of an “ideal” estuary). Furthermore, from the mouth to ∼ 50 km, the variable friction experienced by the incident wave at neap and spring tides produces wave shoaling and damping, respectively. As a result, the wave celerity is largest at neap tide along this lower reach, although the mean water level is highest in spring. Overall, the presented analytical framework is useful for describing the main tidal properties along estuaries considering various forcings (amplitude, period) at the estuary mouth and the proposed method could be applicable to other estuaries with small tidal amplitude to depth ratio and negligible river discharge.info:eu-repo/semantics/publishedVersio

Does unnecessary elective neck treatment affect the prognosis of N0 laryngeal cancer patients?

Among detractors of elective neck (N0) treatments, most suggest that lymphadenectomy removes a barrier to the spread of disease with deleterious immunologic consequences. To test this hypothesis we performed a retrospective comparison of the survival results of N0 laryngeal cancer patients who received unnecessary elective neck treatments (N0-) and those of N0 patients subjected to close and regular follow-up.A retrospective chart review of 749 N0 laryngeal cancer patients treated at the Institute of Otolaryngology-Head and Neck Surgery, University of Florence between January 1980 and January 1993 was performed. Of these, 245 (33\%) received elective neck dissection (ED), while the remaining 504 (67\%) N0 patients were subjected to close and regular follow-up (wait-and-see policy; WS).Of the 245 ED patients, 43 (17.5\%) showed an occult neck disease, while of the 504 WS subjects, 83 (17\%) developed neck metastases during follow-up. Moreover, 15 ED patients subsequently experienced a contralateral occult failure despite a unilateral negative neck specimen (N0-). Thus, ultimately 187 ED (164 of whom were treated unilaterally and 23 bilaterally) and 421 WS patients were used for survival analysis. No differences in terms of postoperative complications, local or distant failure or disease-free or overall actuarial survival were found between the two groups analyzed.These data indicate that unilateral or bilateral removal of cervical lymphatics in the absence of histologically proven lymph node metastases does not negatively affect the prognosis of N0 laryngeal cancer patients who were overtreated to the neck