Manual de fabricación de tabicón sólido de concreto.

TESIS I2.114

Regeneración estructural de un suelo arcilloso por aportes de vermicompost en la chontalpa, tabasco, México

El efecto de la adición de vermicompost de cachaza fue evaluado sobre las propiedades físicas de un suelo vertisol (Oxiaquic hapludert) en la región de la Chontalpa, Tabasco. El vermicompost fue aplicado en enero de 2003 y se mantuvo sin alteración mecánica durante 18 meses. En junio de 2004 fueron medidos la densidad aparente, la distribución y estabilidad de agregados en seco y húmedo, y el carbono total (Ct) asociado a cada tamaño de agregado, y se elaboraron láminas delgadas. Microagregados y macroagregados de los tratamientos de 0 y 60 t ha-1 se visualizaron mediante microscopía electrónica. Los resultados indicaron que la densidad aparente disminuyó con el incremento de la dosis de vermicompost (r = 0.99; p = 0.06). A través de las láminas delgadas, se observó un cambio en la estructura de la superficie del suelo en los tratamientos de 40 y 60 t ha-1. En ambos tratamientos los macroagregados y el espacio poroso fueron más abundantes. Los resultados de los fraccionamientos por tamaño de agregados, tanto en seco como en húmedo, indicaron que hubo más macroagregados estables en los suelos que recibieron mayores dosis de la enmienda orgánica. La mayor cantidad de Ct se asoció con los macroagregados de entre 250 - 500 µm, mientras que a los microagregados (< 250 µm) se asoció menos Ct. La observación de microagregados y macroagregados por microscopía electrónica indicó una ausencia de materia orgánica particulada y macroagregados compuestos por una mayor cantidad de microagregados en el tratamiento de 60 t ha-1

Screening policies, preventive measures and in-hospital infection of COVID-19 in global surgical practices

Background In a surgical setting, COVID-19 patients may trigger in-hospital outbreaks and have worse postoperative outcomes. Despite these risks, there have been no consistent statements on surgical guidelines regarding the perioperative screening or management of COVID-19 patients, and we do not have objective global data that describe the current conditions surrounding this issue. This study aimed to clarify the current global surgical practice including COVID-19 screening, preventive measures and in-hospital infection under the COVID-19 pandemic, and to clarify the international gaps on infection control policies among countries worldwide.Methods During April 2-8, 2020, a cross-sectional online survey on surgical practice was distributed to surgeons worldwide through international surgical societies, social media and personal contacts. Main outcome and measures included preventive measures and screening policies of COVID-19 in surgical practice and centers' experiences of in-hospital COVID-19 infection. Data were analyzed by country's cumulative deaths number by April 8, 2020 (high risk, &gt;5000; intermediate risk, 100-5000; low risk, &lt;100).Results A total of 936 centers in 71 countries responded to the survey (high risk, 330 centers; intermediate risk, 242 centers; low risk, 364 centers). In the majority (71.9%) of the centers, local guidelines recommended preoperative testing based on symptoms or suspicious radiologic findings. Universal testing for every surgical patient was recommended in only 18.4% of the centers. In-hospital COVID-19 infection was reported from 31.5% of the centers, with higher rates in higher risk countries (high risk, 53.6%; intermediate risk, 26.4%; low risk, 14.8%; P&lt;0.001). Of the 295 centers that experienced in-hospital COVID-19 infection, 122 (41.4%) failed to trace it and 58 (19.7%) reported the infection originating from asymptomatic patients/staff members. Higher risk countries adopted more preventive measures including universal testing, routine testing of hospital staff and use of dedicated personal protective equipment in operation theatres, but there were remarkable discrepancies across the countries.Conclusions This large international survey captured the global surgical practice under the COVID-19 pandemic and highlighted the insufficient preoperative screening of COVID-19 in the current surgical practice. More intensive screening programs will be necessary particularly in severely affected countries/institutions

Screening policies, preventive measures and in-hospital infection of COVID-19 in global surgical practices

Background: In a surgical setting, COVID-19 patients may trigger in-hospital outbreaks and have worse postoperative outcomes. Despite these risks, there have been no consistent statements on surgical guidelines regarding the perioperative screening or management of COVID-19 patients, and we do not have objective global data that describe the current conditions surrounding this issue. This study aimed to clarify the current global surgical practice including COVID-19 screening, preventive measures and in-hospital infection under the COVID-19 pandemic, and to clarify the international gaps on infection control policies among countries worldwide. Methods: During April 2-8, 2020, a cross-sectional online survey on surgical practice was distributed to surgeons worldwide through international surgical societies, social media and personal contacts. Main outcome and measures included preventive measures and screening policies of COVID-19 in surgical practice and centers' experiences of in-hospital COVID-19 infection. Data were analyzed by country's cumulative deaths number by April 8, 2020 (high risk, &gt;5000; intermediate risk, 100-5000; low risk, &lt;100). Results: A total of 936 centers in 71 countries responded to the survey (high risk, 330 centers; intermediate risk, 242 centers; low risk, 364 centers). In the majority (71.9%) of the centers, local guidelines recommended preoperative testing based on symptoms or suspicious radiologic findings. Universal testing for every surgical patient was recommended in only 18.4% of the centers. In-hospital COVID-19 infection was reported from 31.5% of the centers, with higher rates in higher risk countries (high risk, 53.6%; intermediate risk, 26.4%; low risk, 14.8%; P &lt; 0.001). Of the 295 centers that experienced in-hospital COVID-19 infection, 122 (41.4%) failed to trace it and 58 (19.7%) reported the infection originating from asymptomatic patients/staff members. Higher risk countries adopted more preventive measures including universal testing, routine testing of hospital staff and use of dedicated personal protective equipment in operation theatres, but there were remarkable discrepancies across the countries. Conclusions: This large international survey captured the global surgical practice under the COVID-19 pandemic and highlighted the insufficient preoperative screening of COVID-19 in the current surgical practice. More intensive screening programs will be necessary particularly in severely affected countries/institutions

Surgeons' fear of getting infected by COVID19: A global survey.

Surgeons' fear of getting infected by COVID19: A global surve