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In this work, we consider a fractional extension of the Klein–Gordon–Zakharov system which describes the propagation of strong turbulences on the Langmuir wave in a high-frequency plasma. Both components consider space-fractional derivatives of the Riesz type, and initial-boundary conditions are imposed on a closed and bounded interval of the real numbers. In a first stage, we show that the total energy of the system is conserved, and that the global solutions of the system are bounded. Motivated by these results, we propose a finite-difference scheme to approximate the solutions, and a discrete form of the energy functional. The advantage of the discretization proposed in this work lies in that the difference equations to solve the component equations are decoupled. This implies that the numerical schemes can be solved separately at each temporal step. We establish rigorously the existence of solutions, as well as the capability of the scheme to conserve the discrete energy. The method has a second-order consistency in both space and time. Moreover, using a discrete form of the energy method, we establish mathematically that the finite-difference scheme is stable and quadratically convergent. We provide some simulations to show that the proposed methodology is quadratically convergent and that it preserves the total energy of the system.

Departing from an initial-boundary-value problem governed by a Klein–Gordon–Zakarov system with fractional derivatives in the spatial variable, we provide an explicit finite-difference scheme to approximate its solutions. In agreement with the continuous system, the method proposed in this work is also capable of preserving the energy of the system, and the energy quantities are nonnegative under flexible parameter conditions. The boundedness, the consistency, the stability and the convergence of the technique are also established rigorously. The method is easy to implement, and the computer simulations confirm the main analytical and numerical properties of the new model.

Neoplasic stenoses of the left colon are most frequently caused by primary colon carcinoma, infiltration from an external tumour and great adenomatous polyps. These patients often develop obstruction as their first symptom, leading to emergency surgical procedures in adverse circumstances and without an appropriate intestinal preparation that might prevent primary anastomosis. Therapeutic options for this event, such as Hartmann's resection, subtotal colectomy or anterograde colon lavage are not always possible. In these patients a colostomy is performed that requires future reoperation for reconstruction of the intestinal transit. Transtumoral self-expandable stenting followed by elective surgery might be the best option in these cases, as well as an alternative to surgery in non-operable patients.Twenty four patients treated with this procedure in the past four years were divided in two groups. In group 1 (14 patients), the stent was placed as a permanent and palliative measure for the management of the disease. In group 2 (10 patients), the stent was placed temporarily for the management of the intestinal obstruction and latter the patients underwent elective surgery with fully preoperative and extension study and an appropriate preparation of the colon in order to allow reliable primary anastomosis.There were no hospital mortality nor stent migrations. There was only one complication (perforation caused by the stent) that required emergency surgery, but with any further complications. Failure to place the stent occurred in one patient.Self-expandable stents relieve neoplasic colon obstructions and allow to complete the study protocol, followed by elective surgery associated to less morbi-mortality. In patients with advanced or irresectable cancer, they provide a palliative and safe alternative to surgery, with satisfactory results.

We present a patient with obstructive unresectable carcinoma of the gastric antrum. An expandable stent was placed endoscopically along the tumor to paliate obstruction. Such a procedure allowed unrestricted oral feeding of the patient up to death six months later.

A pair of omphalopagous conjoined twins is presented. The girls were delivered by cesarean section, weighing together 4.330 g; Plain X-ray demonstrates separated GI tract. Hepatic scintigraphy delineated both livers, but not a common liver mass, which was found at operation. Following adequate preparation, surgical procedure was performed at the 11th day. This is the second case reported in the Spanish literature with survival of both twins.

Authors report two cases of prostatic utricle cysts, one of which was operated. They collect from literature 20 other cases in children aged ten years or less. Natural history of patients is reported. They also comment on the symptoms and associated anomalies and conclude discussing diagnostic and operative procedures available in these patients.

We report two cases of complete avulsion at the ureteropelvic junction in children. In both cases the injury was repaired successfully because of an early diagnosis and treatment based in a high degree of suspicion, confirmed by IVP. A review of the literature revealed 29 cases in children.

We present the case of a 12-year old girl that presented during a four month period urinary incontinence alternating with normal micturitions, vaginal flow and bacteriuria. IVP shows a pyeloureteral duplication in the right side. The superior and inferior calyceal groups meet in a normal ureter whereas the middle calyceal group is open in one megaureter with ureterocele in medial and extravesical situation, probably vaginal or uterine. During operation a third blind ureter was found connected to the "ureterocele" and medial to the ectopic megaureter. A bibliographical survey is made and surgical and embriological data are commented.

Chagas-Mazza disease is an endemic infection of chronic evolution and is essentially American. Its transmission by vinchuca in Argentine has created a medical, psychological and social problem of great and important significance. The basic, preliminary and social study carried out in a hospital unit, showed in the population attended, precarious socioenvironmental conditions during childhood and adolescence and the almost total lack of basic information on the disease. Interviews, inquests, questionnaires, group actions, team work, direct dialogues, counselling and guidance groups and the guiding to specialized institutions, constitute a synthesis of the task developed which, in its preliminary stage, showed sufficient reasons to continue the control of health during pregnancy, childbirth, puerperium and lactation.

We were not able to find other cases of this association in the literature. The key clinical sign is the presence of two urethral meatus. The treatment of the urethral anomalies varies in relation with the possible functional disorders.