La caracterización de las propiedades del suelo mediante análisis de laboratorio es parte esencial en el diagnóstico del potencial de uso de las tierras y de su fertilidad. Los análisis químicos convencionales son costosos y demorados, lo que dificulta la adopción de tecnologías de gestión de cultivos, como la agricultura de precisión. El objetivo del presente trabajo fue evaluar el potencial de la espectroscopía de reflectancia difusa por infrarrojo lejano (NIR) en la predicción del carbono y del nitrógeno de un Typic Hapludox. Se recolectaron 1.240 muestras en los horizontes A y B, para determinar los contenidos de carbono total (TC) y nitrógeno total (TN), obtener las respuestas espectrales NIR y elaborar los modelos mediante regresión por mínimos cuadrados parciales. El uso de las espectroscopía de reflectancia difusa y de técnicas estadísticas permitió la cuantificación del TC, con modelos de predicción adecuados con bajo número de muestras, desviación residual de la predicción RPD mayores de 2,0, R² mayores de 0,80 y error cuadrático medio RMSE bajos. Para TN no se obtuvieron modelos con buen nivel de predicción. Para TC, los resultados obtenidos a partir de los modelos NIR pudieron integrarse directamente en las evaluaciones geoestadísticas, obteniendo mapas digitales y espectro-digitales similares. El uso de las técnicas pedométricas, mostró resultados promisorios para estos suelos y se constituye en una base para el desarrollo de esta área de investigación de la ciencia del suelo en Colombia.

The characterization of soil properties through laboratory analysis is an essential part of the diagnosis of the potential use of lands and their fertility. Conventional chemical analyzes are expensive and time consuming, hampering the adoption of crop management technologies, such as precision agriculture. The aim of the present paper was to evaluate the potential of near-infrared (NIR) diffuse reflectance spectroscopy for the prediction of the carbon and nitrogen of Typic Hapludox. In the A and B horizons, 1,240 samples were collected in order to determine the total carbon (TC) and nitrogen (TN) contents, obtain the NIR spectral curve, and build models using partial least squares regression. The use of diffuse reflectance spectroscopy and statistical techniques allowed for the quantification of the TC with adequate models of prediction based on a small number of samples, an residual prediction deviation RPD greater than 2.0, an R² greater than 0.80 and a low root mean square error RMSE. For TN, models with a good level of prediction were not obtained. The results based on the NIR models were able to be integrated directly into the geostatistical evaluations, obtaining similar digital maps from the observed and predicted TC. The use of pedometric techniques showed promising results for these soils and constitutes a basis for the development of this area of research on soil science in Colombia.

Objective. To validate the utility of 4D Blood Flow and Navier-Stokes equations to create relative pressure (RP) maps in the aorta and pulmonary artery (PA) in healthy volunteers and patients with repaired tetralogy of Fallot (TOF). Methods. A 4D flow sequence of whole heart and its major vessels was acquired in 10 healthy volunteers and 6 patients with repaired TOF. The root of the ascending aorta was used as the reference point to calculate RP along five different points of this area. In addition, relative pressure of both right and left PA was measured as correlated to absolute pressure. Results. Patients with repaired TOF showed greater pulmonary artery (PA) relative pressure differences between maximum and minimum values when compared to volunteers (p <0.05). Additionally, aortic relative pressures had an excellent correlation with published data, whether using 4D flow or by catheterization. Conclusions. 4D Flow MRI may represent a new non-invasive and non operator-dependent diagnostic tool in CV disease management.

Objetivo. Utilizar 4D Flow y las ecuaciones de Navier-Stokes para obtener mapas de presiones relativas (PR) en la Aorta y Arteria Pulmonar (AP) de voluntarios y pacientes con Tetralogía de Fallot reparada (TOFr). Métodos. En 10 voluntarios y 6 pacientes con TOFr se adquirió la secuencia 4D flow del corazón y sus principales vasos. La raíz de la Aorta Ascendente se utilizó como referencia para calcular las PR a esta zona en cinco puntos distintos. Además, se midió la PR de la AP derecha e izquierda respecto a la AP. Resultados. Los pacientes con TOFr tuvieron diferencias de PR entre los valores máximos y mínimos más grandes que los voluntarios en la AP (p<0,05). Adicionalmente, las PR de la aorta tuvieron una excelente correlación con datos publicados utilizando 4D flow y mediante cateterización. Conclusiones. 4D Flow podría constituir una nueva herramienta diagnóstica, no invasiva, ni operador dependiente, en el manejo de patologías CV.

Se evaluaron el uso de recursos y la sostenibilidad de tres sistemas agroforestales (bosque secundario- BS, tala y quema-TQ y sistema conservacionista Quesungual-SAQ). Se utilizaron datos de 15 parcelas de 200 m² ubicadas entre 14° 05' N y 88° 30' W y transformicidades reportadas en otros estudios. Los mayores valores de emergía se presentaron en la variable Lluvia (1.35E15 sej/ha por año) y las mayores diferencias de emergía entre sistemas se observaron en suelo erosionado, especialmente en TQ, BS y SAQ tuvieron mayor Razón de Carga Ambiental que TQ (0.63, 0.14 y 0.02, respectivamente). El sistema TQ presenta el valor más alto del índice de Huella Ecológica seguido por SAQ y BS. El índice de Sostenibilidad de Emergía del sistema TQ fue 34.8, el de SAQ = 135.6 y el de BS = 4123.8, con mayores valores de sostenibilidad en el SAQ y el BS, lo cual indica que son sistemas que favorecen el uso de recursos renovables y locales.

Resource use and sustainability of three agroforestry systems (Secondary Woods - BS; Fell and Burn - TQ; and Quesungal Conservation mode - SAQ) were evaluated by analyzing data from fifteen 200 m² plots (14° 05' N; 88° 30' W), making use of transformity values reported in other related studies. The highest emergy values were observed for the variable rain (1.35E15 sej/ha per year); and the largest emergy differences were found in eroded soils, especially those of TQ. BS and SAQ exhibited a greater Environmental Load Ratio than TQ (0.63, 0.14 and 0.02, respectively). TQ showed the largest Ecological Footprint Index value, followed by SAQ and BS. Emergy Sustainability Index for TQ was 34.8, whereas SAQ and BS reached respective values of 135.6 and 4,123.8. The latter two data, as compared to the former, reveal how these systems (SAQ and BS) favor the use of local renewable resources.

A series of N-methyl-2-R1,R2-5-R3,R4- 1,3-oxazines (where R are either H or p-nitro phenyl group and R3,4 = H or CH3- group) have been theoretically studied by ab initio methods in the frame of MO theory. Optimized geometries were obtained at HF and B3LYP/6-31G" levels, whereas energies were derived at MP2 and B3LYP levels employing the same basis set. Geometries obtained at DFT level are needed to obtain consistent values and good correlations between the experimental and theoretical ¹H-NMR data. The nitrogen lone pair would be axial orientated in I and II, since the N-methyl group lies in the equatorial position in the gas phase, whereas in compounds III and IV the methyl axial conformers increase their concentration, implying that inversion of the nitrogen lone pair takes place in an appreciable extent. PCM method predicts that solvents (CCl4, CHCl3, CH2Cl2) produce a significant effect on conformers preference, but just a modest influence on the equilibrium geometries and ¹H-NMR properties.

Background: Tracheal stenosis is a common complication of intubation or tracheostomy. Aim: To report the experience with tracheal stenosis and propose a new classification to standardize its management. Material and Methods: Prospective study of 32 patients aged 17 to 79 years, 23 males. Twenty had a benign and 12 a malignant stenosis, four of which had tracheoesophageal fistula. Seven patients had a Type I stenosis, defined as a lesion of less than 1 cm in length, five had a type II lesion, defined as a diffuse lesion of less than 3 cm in length and 20 cases had a type III lesion defined as a stenosis of more than 3 cm, in length or multiple lesions or tracheomalacia. Patients with type I stenosis were treated with electro coagulation, those with type II lesions were subjected to a primary resection and tracheal end-to-end anastomosis and type III patients were treated using a dynamic stent. Results: Evolution after treatment was favorable with disappearance of clinical manifestations, improvement in functional capacity and modified Borg Scale score in 69% of the patients. Life quality and flow-volume curves improved in 100% of patients. Seven patients died due to progression of cancer and one committed suicide. Conclusions: The classification of tracheal stenosis in three types, depending on the morphology and extent of the lesion allows a better planning of treatment

Objetivo del estudio: Proponer una nueva clasificación para la estenosis traqueal para estandarizar el manejo. Diseño: Estudio prospectivo realizado entre Octubre del 2002 y septiembre del 2005 en el Hospital San José. Pacientes: Se incluyeron 32 pacientes, 9 mujeres y 23 varones, con estenosis traqueal de etiología benigna (20 casos) y maligna (12 casos), de los cuales 4 tenían fístula traqueoesofágica. Método: Los pacientes fueron divididos en tres grupos de acuerdo a la morfología, longitud, número y localización de la o las lesiones que causaban estenosis. Según lo anterior Tipo I (7 casos; 22%), Tipo II (5 casos; 16%). Tipo III (20 casos; 62%). Intervenciones: Las estenosis Tipo I fueron tratadas mediante electrocoagulación. Las Tipo II con cirugía (resección y anastomosis traqueal termino-terminal primaria). Las Tipo III utilizando un stent dinámico. Resultados: La evolución posteriora la realización del procedimiento correspondiente a cada grupo, fue favorable, mejorando la capacidad funcional, demostrado por la realización de curva flujo-volumen y la desaparición de manifestaciones clínicas (según escala de Borg modificada) en el 69% de los pacientes, con una calidad de vida que mejora en el 100% de los casos, objetivado mediante el cuestionario de Saint-George. La mortalidad global es de 25% (8/32), no atribuible al tratamiento otorgado. Conclusiones: Consideramos que la clasificación propuesta es un método opera-cional, de fácil utilización, que permite planificar un tratamiento independientemente de la etiología de la estenosis traqueal, permitiendo asignar un pronóstico y mejorar calidad de vida

The application of the Principal Component of Analysis (PCA) over the theoretical data of a series of substituted 1,3-oxazines helps to determine the factors that rule the conformational equilibrium. Repulsive and intertribal syn-1,3-diaxial interactions have been used as determiners for the axial structures, whereas dipolar interactions are preferred in the equatorial conformation. Theoretical variables such as hardness, charges, nuclear repulsion energy and bond order in the different nuclear sectors have been used. PCA method has been successfully used in predicting the hyperconjugative interactions that play an important role in the conformational equilibrium between a given pair of conformers of 1,3-oxazines. The studied 1,3-oxazines belong to three different groups of structures having the heterocyclic ring as a common feature. The axial structures are stabilized by two-electron/two-orbital interactions, whereas the equatorial structures are believed to be stabilized by syn-1,3-diaxial and dipole-dipole interactions

A ZINDO/1 quantum-chemical structure-affinity relationship study is presented for the interaction of a group of 3-substituted morphinans with mu, delta and kappa opioid receptors. From this and previous work it is concluded that: 1. Receptor selectivity is regulated by different electronic densities located sometimes at the same atomic center. 2. The equations for the binding to the three opiate receptors are consistent with previous results obtained for other kinds of opiate molecules. 3. Internal occupied molecular orbitals are very important in regulating receptor affinity (and selectivity). 4. The role of molecular orbitals in the saturated rings needs further analysis through the study of more molecular systems interacting with opiate receptors

Phenotypic diversity has been described in the central repeated region of the circumsporozoite protein (CSP) from Plasmodium vivax. Two sequences VK210 (common) and VK247 (variant) have been found widely distributed in P. vivax isolates from several malaria endemic areas around the world. A third protein variant called P. vivax-like showing a sequence similar to the simian parasite P. simio-ovale has also been described. Here, using an immunofluorescent test and specific monoclonal antibodies, we assessed the presence of two of these protein variants (VK210 and VK247) in laboratory produced sporozoite. Both sequences were found in parasite isolates coming from different geographic regions of Colombia. Interestingly, sporozoites carrying the VK247 sequence were more frequently produced in Anopheles albimanus than sporozoites with the VK210 sequence. This difference in sporozoites production was statistically significant (p <0.05, Kruskal-Wallis); not correlation was found with parameters as the total number of parasites or gametocytes in blood from human donors used to feed mosquitoes. Previous studies in the same region have shown a higher prevalence of anti-VK210 antibodies which in theory may suggest their role in blocking the development of sporozoites carrying the CSP VK210 sequence.