Concentrations of N, P, and K in the corn leaf as affected by weather indexes and selected soil and management factors

The major objectives of this research were: (1) to test and select weather indexes relative to various periods of the growing season in the presence of soil and management factors for each of the N, P, and K corn leaf concentrations; (2) to use and evaluate a summation technique to relate each leaf nutrient to weather indexes computed for various time periods; and (3) to develop a regression prediction model for each leaf nutrient on weather, soil, and management variables. Concentrations of N, P, and K in the corn leaf at the silking stage and related data were from 1927 observations in 15 Iowa counties representing most soil association areas;A number of excess moisture, moisture stress, and precipitation indexes for various periods of the growing season were evaluated by correlation and regression analysis. A summation technique was applied to 5-day moisture stress and precipitation indexes to assess their effects on the leaf nutrients as well as those of their interactions with selected soil and management variables;The early-season moisture and precipitation indexes had negative effects on the leaf nutrients, while less moisture stress and higher rainfall just prior to silking increased both leaf N and P and midseason rainfall increased leaf K. The summation technique was useful to describe the effects of the weather indexes and of their interactions with other variables on leaf nutrients;The final leaf N model had 76 variates and an R(\u272) of 0.419. From the explained variability in leaf N, 8.6% was due to the weather indexes, 4.5% to their interactions with other variables, and 1.8% to interactions between soil and management variables;The final leaf P model had 75 variates and an R(\u272) of 0.512. From the explained variability in leaf P, 8.8% was due to the weather indexes, 3.3% to their interactions with other variables, and 4.2% to interactions between soil and management variables;The final leaf K model had 58 variates and an R(\u272) of 0.683. From the explained variability in leaf K, 3.5% was due to the weather indexes, 1.1% to their interactions with other variables, and 2.1% to interactions between soil and management variables

Sostenibilidad de dalea lutea en bosque mixto y pastizal en tenancingo, Estado de México

Sostenibilidad de Dalea luteaen bosque mixto y pastizal en Tenancingo, Estado de México. El objetivo del presente trabajo fue analizar la dinámica poblacional, el comportamiento anual y evaluar la sostenibilidad ecológica de una población deD. lutea(Cav.) Willd. La presente investigación se llevó a cabo en la comunidad de Chalchihuapán, Tenancingo Estado de México (México) durante el periodo de otoño 2002 a otoño 2004. Se evaluó una población de Dalea lutea (Cav.) Willd. en bosque mixto y en pastizal inducido. Se marcaron para ello cuatro parcelas por zona y se clasificaron los individuos en tres tipos: plántulas, juveniles y adultas; los datos se trataron con análisis de varianza, prueba de medias y fórmulas de sostenibilidad. La población de D. luteaaumentó durante el verano-otoño y disminuyó durante el periodo invierno-primavera. Los muestreos presentaron diferencias estadísticas para plántulas y juveniles, no así en adultas, pero cuando estas clases se evaluaron dentro de las zonas no difirieron estadísticamente; el mayor número de individuos se reportó durante el verano, otoño e invierno de 2003. Respecto a sostenibilidad, el pastizal mostró al final del periodo un restablecimiento de 59,5 y 41% para plántulas y plantas adultas, respectivamente, y una disminución de 79% en juveniles. Mientras que en bosque mixto las plántulas y las juveniles decrecieron en 4,4 y 16,2%, y las adultas se restablecieron en 25,1%. La población de D. luteaaumentó o disminuyó conforme la época de muestreo, y el número de individuos estuvo afectado por la precipitación. Bajo las condiciones actuales de recolecta, la población de D. lutease mantuvo estable en bosque mixto y se restableció mejor en la zona de pastizal.Universidad Autónoma del Estado de Méxic

Plantas silvestres con uso artesanal en el Centro de México

Los artesanos de Tenancingo, México combinan los tallos de diferentes especies vegetales para conferir belleza y resistencia a sus piezas. En canastas grandes utilizan los tallos de Salix bonplandiana H.B.K., Gymnosperma glutinosum (Spreng.) Lesson y Cornus excelsa H.B.K.; las pequeñas se elaboran con Dalea lutea (Cav.) Willd. y Viburnum elatum Benth.; Taxodium mucronatum Ten. se utiliza en el fondo de la canasta. El periodo de recolecta va de febrero a noviembre. Los artesanos de la zona han generado conocimientos valiosos del uso y aprovechamiento de la biodiversidad existente en la zona de estudio para elaborar cestería.Universidad Autónoma del Estado de México Proyecto 1825/2004. Al Herbario CODAGEM por la identificación de las especies en estudio

Concentrations of N, P, and K in the corn leaf as affected by weather indexes and selected soil and management factors

The major objectives of this research were: (1) to test and select weather indexes relative to various periods of the growing season in the presence of soil and management factors for each of the N, P, and K corn leaf concentrations; (2) to use and evaluate a summation technique to relate each leaf nutrient to weather indexes computed for various time periods; and (3) to develop a regression prediction model for each leaf nutrient on weather, soil, and management variables. Concentrations of N, P, and K in the corn leaf at the silking stage and related data were from 1927 observations in 15 Iowa counties representing most soil association areas;A number of excess moisture, moisture stress, and precipitation indexes for various periods of the growing season were evaluated by correlation and regression analysis. A summation technique was applied to 5-day moisture stress and precipitation indexes to assess their effects on the leaf nutrients as well as those of their interactions with selected soil and management variables;The early-season moisture and precipitation indexes had negative effects on the leaf nutrients, while less moisture stress and higher rainfall just prior to silking increased both leaf N and P and midseason rainfall increased leaf K. The summation technique was useful to describe the effects of the weather indexes and of their interactions with other variables on leaf nutrients;The final leaf N model had 76 variates and an R('2) of 0.419. From the explained variability in leaf N, 8.6% was due to the weather indexes, 4.5% to their interactions with other variables, and 1.8% to interactions between soil and management variables;The final leaf P model had 75 variates and an R('2) of 0.512. From the explained variability in leaf P, 8.8% was due to the weather indexes, 3.3% to their interactions with other variables, and 4.2% to interactions between soil and management variables;The final leaf K model had 58 variates and an R('2) of 0.683. From the explained variability in leaf K, 3.5% was due to the weather indexes, 1.1% to their interactions with other variables, and 2.1% to interactions between soil and management variables.</p

Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study

Background Current management practices and outcomes in weaning from invasive mechanical ventilation are poorly understood. We aimed to describe the epidemiology, management, timings, risk for failure, and outcomes of weaning in patients requiring at least 2 days of invasive mechanical ventilation. Methods WEAN SAFE was an international, multicentre, prospective, observational cohort study done in 481 intensive care units in 50 countries. Eligible participants were older than 16 years, admitted to a participating intensive care unit, and receiving mechanical ventilation for 2 calendar days or longer. We defined weaning initiation as the first attempt to separate a patient from the ventilator, successful weaning as no reintubation or death within 7 days of extubation, and weaning eligibility criteria based on positive end-expiratory pressure, fractional concentration of oxygen in inspired air, and vasopressors. The primary outcome was the proportion of patients successfully weaned at 90 days. Key secondary outcomes included weaning duration, timing of weaning events, factors associated with weaning delay and weaning failure, and hospital outcomes. This study is registered with ClinicalTrials.gov, NCT03255109. Findings Between Oct 4, 2017, and June 25, 2018, 10 232 patients were screened for eligibility, of whom 5869 were enrolled. 4523 (77·1%) patients underwent at least one separation attempt and 3817 (65·0%) patients were successfully weaned from ventilation at day 90. 237 (4·0%) patients were transferred before any separation attempt, 153 (2·6%) were transferred after at least one separation attempt and not successfully weaned, and 1662 (28·3%) died while invasively ventilated. The median time from fulfilling weaning eligibility criteria to first separation attempt was 1 day (IQR 0–4), and 1013 (22·4%) patients had a delay in initiating first separation of 5 or more days. Of the 4523 (77·1%) patients with separation attempts, 2927 (64·7%) had a short wean (≤1 day), 457 (10·1%) had intermediate weaning (2–6 days), 433 (9·6%) required prolonged weaning (≥7 days), and 706 (15·6%) had weaning failure. Higher sedation scores were independently associated with delayed initiation of weaning. Delayed initiation of weaning and higher sedation scores were independently associated with weaning failure. 1742 (31·8%) of 5479 patients died in the intensive care unit and 2095 (38·3%) of 5465 patients died in hospital. Interpretation In critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates

Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study

Background: Current management practices and outcomes in weaning from invasive mechanical ventilation are poorly understood. We aimed to describe the epidemiology, management, timings, risk for failure, and outcomes of weaning in patients requiring at least 2 days of invasive mechanical ventilation. Methods: WEAN SAFE was an international, multicentre, prospective, observational cohort study done in 481 intensive care units in 50 countries. Eligible participants were older than 16 years, admitted to a participating intensive care unit, and receiving mechanical ventilation for 2 calendar days or longer. We defined weaning initiation as the first attempt to separate a patient from the ventilator, successful weaning as no reintubation or death within 7 days of extubation, and weaning eligibility criteria based on positive end-expiratory pressure, fractional concentration of oxygen in inspired air, and vasopressors. The primary outcome was the proportion of patients successfully weaned at 90 days. Key secondary outcomes included weaning duration, timing of weaning events, factors associated with weaning delay and weaning failure, and hospital outcomes. This study is registered with ClinicalTrials.gov, NCT03255109. Findings: Between Oct 4, 2017, and June 25, 2018, 10 232 patients were screened for eligibility, of whom 5869 were enrolled. 4523 (77·1%) patients underwent at least one separation attempt and 3817 (65·0%) patients were successfully weaned from ventilation at day 90. 237 (4·0%) patients were transferred before any separation attempt, 153 (2·6%) were transferred after at least one separation attempt and not successfully weaned, and 1662 (28·3%) died while invasively ventilated. The median time from fulfilling weaning eligibility criteria to first separation attempt was 1 day (IQR 0-4), and 1013 (22·4%) patients had a delay in initiating first separation of 5 or more days. Of the 4523 (77·1%) patients with separation attempts, 2927 (64·7%) had a short wean (≤1 day), 457 (10·1%) had intermediate weaning (2-6 days), 433 (9·6%) required prolonged weaning (≥7 days), and 706 (15·6%) had weaning failure. Higher sedation scores were independently associated with delayed initiation of weaning. Delayed initiation of weaning and higher sedation scores were independently associated with weaning failure. 1742 (31·8%) of 5479 patients died in the intensive care unit and 2095 (38·3%) of 5465 patients died in hospital. Interpretation: In critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates. Funding: European Society of Intensive Care Medicine, European Respiratory Society