Patologías quirúrgicas en el embarazo / Surgical pathologies in pregnancy

Introducción: una de cada 50 mujeres presentará durante su embarazo dolor abdominal potencialmente quirúrgico y una de cada 600 mujeres embarazadas requerirá de cirugía abdominal no obstétrica durante el embarazo. Objetivos: determinar la frecuencia y características demográficas y clínicas de patologías quirúrgicas durante el embarazo en pacientes internadas en el Hospital Nacional del año 2010 al 2014. Metodología: diseñoobservacional, descriptivo, retrospectivo de corte trasversal. Población estudiada: gestantes y/o puérperas atendidas en el Hospital Nacional con diagnóstico de patologías quirúrgicas durante los años 2010-2014. Muestreo no probabilístico según criterio. Resultados: se hallaron 76 mujeres (0,5%) con patologías quirúrgicas, la edad media fue 27 ± 6,2 años. La litiasis vesicular y la apendicitis aguda fueron las más frecuentes. La media de edad gestacional fue 28 ± 9,4 semanas. Las complicaciones fueron abdomen agudo y pancreatitis aguda, requiriendo cirugía 39 (51,3%) pacientes. Conclusiones: la frecuencia de patologías quirúrgicas fue menor al 1%, las patologías biliares y apendiculares fueron las más frecuentes.

Introduction: One in 50 women during pregnancy will potentially present surgical abdominal pain and one of every 600 pregnant women will require nonobstetric abdominal surgery during pregnancy. To determine the frequency and types of surgical pathologies during pregnancy in patients hospitalized in the HNI from 2010 to 2014. Methodology: observational, descriptive, retrospective study population crosscut: population studied pregnant and / or postpartum women treated at the National Hospital with a diagnosis of surgical pathologies during the years 2010-2014, no probabilistic sampling according to criteria. Results: 76 (0.5%) with surgical pathologies, median age were found: 27 ± 6.2 years, Cholelithiasis and acute appendicitis were the most frequent. Median gestational age was 28 ± 9.4 weeks. The complication were acute abdominal patology and acute pancreatitis, requiring surgery 39 (51.3%) patients. Conclusions: The frequency of surgical pathologies were less than 1%, biliary and appendicular pathology were the most frequent.

Multimode resistive switching in single ZnO nanoisland system.

Resistive memory has attracted a great deal of attention as an alternative to contemporary flash memory. Here we demonstrate an interesting phenomenon that multimode resistive switching, i.e. threshold-like, self-rectifying and ordinary bipolar switching, can be observed in one self-assembled single-crystalline ZnO nanoisland with base diameter and height ranging around 30 and 40 nm on Si at different levels of current compliance. Current-voltage characteristics, conductive atomic force microscopy (C-AFM), and piezoresponse force microscopy results show that the threshold-like and self-rectifying types of switching are controlled by the movement of oxygen vacancies in ZnO nanoisland between the C-AFM tip and Si substrate while ordinary bipolar switching is controlled by formation and rupture of conducting nano-filaments. Threshold-like switching leads to a very small switching power density of 1 × 10(3) W/cm(2).

Resistive switching in single epitaxial ZnO nanoislands.

Resistive memory is one of the most promising candidates for next-generation nonvolatile memory technology due to its variety of advantages, such as simple structure and low-power consumption. Bipolar resistive switching behavior was observed in epitaxial ZnO nanoislands with base diameters and heights ranging around 30 and 40 nm, respectively. All four different states (initial, electroformed, ON, and OFF) of the nanoscale resistive memories were measured by conductive atomic force microscopy immediately after the voltage sweeping was performed. Auger electron spectroscopy and other experiments were also carried out to investigate the switching mechanism. The formation and rupture of conducting filaments induced by oxygen vacancy migration are responsible for the resistive switching behaviors of ZnO resistive memories at the nanoscale.

Carbon nanotube memory by the self-assembly of silicon nanocrystals as charge storage nodes.

A memory structure based on self-aligned silicon nanocrystals (Si NCs) grown over Al(2)O(3)-covered parallel-aligned carbon nanotubes (CNTs) by gas source molecular beam epitaxy is reported. Electrostatic force microscopy characterizations directly prove the charging and discharging of discrete NCs through the Al(2)O(3) layer covering the CNTs. A CNT field effect transistor based on the NC/CNT structure is fabricated and characterized, demonstrating evident memory characteristics. Direct tunneling and Fowler-Nordheim tunneling phenomena are observed at different programming/erasing voltages. Retention is demonstrated to be on the order of 10(4) s. Although there is still plenty of room to enhance the performance, the results suggest that CNT-based NC memory with diminutive CNTs and NCs could be an alternative structure to replace traditional floating gate memory.