Seismic cycles, size of the largest events, and the avalanche size distribution in a model of seismicity.

We address several questions on the behavior of a numerical model recently introduced to study seismic phenomena, which includes relaxation in the plates as a key ingredient. First, we make an analysis of the scaling of the largest events with system size and show that, when parameters are appropriately interpreted, the typical size of the largest events scale as the system size, without the necessity to tune any parameter. Second, we show that the temporal activity in the model is inherently nonstationary and obtain from here justification and support for the concept of a "seismic cycle" in the temporal evolution of seismic activity. Finally, we ask for the reasons that make the model display a realistic value of the decaying exponent b in the Gutenberg-Richter law for the avalanche size distribution. We explain why relaxation induces a systematic increase in b from its value b≃0.4 observed in the absence of relaxation. However, we have not been able to justify the actual robustness of the model in displaying a consistent b value around the experimentally observed value b≃1.

[Improvement of fecal incontinence with silicone implants in patients with internal anal sphincter injury: First report in North America]. / Mejoría de la incontinencia fecal con implantes de silicón en pacientes con lesiones del esfínter anal interno: primer informe en Norteamérica.

The injection of bulking agents has been described as a useful treatment of urinary and fecal incontinence. Among them, silicone implants have shown benefits in patients with internal anal sphincter (IAS) injury. We describe two patients with a history of hemorrhoidectomy and IAS injuries, which underwent placement of silicone implants. The implants were inserted into the intersphincteric space and the IAS under ultrasound guidance. The Wexner continente score fell from 17 and 19 before treatment, to 6 and 8 at six months follow up, respectively. Patients had no postoperative complications or implants migration. In our patients, injection of silicone implants improved fecal continence score, without postoperative complications or implants migration at six month follow up.

[Surgical treatment of rectal cancer]. / Tratamiento quirúrgico del cáncer de recto.

Rectal affection accounts for 30% of colorectal cancer. The standard of treatment is surgical resection, which often is curative. For superior and middle-rectal involvement, low anterior resection (LAR) is the preferred procedure. For tumors involving the lower portion of the rectum, abdominoperineal resection (APR) or LAR are the options of treatment, depending on sphincter involvement. The main surgical objective is to achieve a R0 resection with an appropriated total mesorrectal excision, greater number of lymph nodes and negative distal and radial margins. These surgical parameters have been used as quality indicators and have prognostic implications in terms of overall and disease-free survival. Total mesorectal excision with preservation of hypogastric nerves has shown a reduction in rates of sexual and bladder dysfunction as well as lower local recurrence. At specialized centers such procedures are performed by minimal invasive surgery; however the number of meta-analysis is scarce.

[The migration problem in the pan-Amazon region: a theoretical approximation and a methodological alternative]. / El problema migratorio en la pan-amazonia: una aproximacion teorica y una alternativa metodologica

PIP: Some theoretical concepts concerning the study of migration in the Amazon region of South America are discussed. The concepts considered include differences in the definitions of the region used.^ieng