Multiple motion encoding in Phase-Contrast MRI:A general theory and application to elastography imaging

While MRI allows to encode the motion of tissue in the magnetization’s phase, it remains yet a challenge to obtain high fidelity motion images due to wraps in the phase for high encoding efficiencies. Therefore, we propose an optimal multiple motion encoding method (OMME) and exemplify it in Magnetic Resonance Elastography (MRE) data. OMME is formulated as a non-convex least-squares problem for the motion using an arbitrary number of phase-contrast measurements with different motion encoding gradients (MEGs). The mathematical properties of OMME are proved in terms of standard deviation and dynamic range of the motion’s estimate for arbitrary MEGs combination which are confirmed using synthetically generated data. OMME’s performance is assessed on MRE data from in vivo human brain experiments and compared to dual encoding strategies. The unwrapped images are further used to reconstruct stiffness maps and compared to the ones obtained using conventional unwrapping methods. OMME allowed to successfully combine several MRE phase images with different MEGs, outperforming dual encoding strategies in either motion-to-noise ratio (MNR) or number of successfully reconstructed voxels with good noise stability. This lead to stiffness maps with greater resolution of details than obtained with conventional unwrapping methods. The proposed OMME method allows for a flexible and noise robust increase in the dynamic range and thus provides wrap-free phase images with high MNR. In MRE, the method may be especially suitable when high resolution images with high MNR are needed

Evaluación de la macrofauna en cinco leñosas perennes en el Centro de Investigaciones Amazónicas “Cesar Augusto Estrada” CIMAZ Macagual

Se realizaron los muestreos para biología del suelo en cinco especies arbóreas diferentes en distintas zonas del centro de investigaciones amazónicas Macagual, arboles tales como Guayaba (Psidium guajaba); Carbón (Zygia longifolia); Bilibil (Guarea guidonia); Guayabo Coronillo (Bellucia sp.); Cobre (Andira inermis). Para la extracción de la macrofauna del suelo, se implementó la metodología del monolito el cual se realizó ocho veces por árbol, las cuales se realizaron cuatro repeticiones dentro de la copa del árbol y cuatro a exposición total fuera del árbol, teniendo en cuenta los puntos cardinales (Norte, Sur, Oriente, Occidente). Las muestras de suelo se analizaron para la extracción de la macrofauna y su posterior identificación por órdenes, de los cuales las hymenopteras y las haplotaxias presentaron los mayores rangos de diversidad en macrofauna

Effect of Thermal Stress on Tissue Ultrastructure and Metabolite Profiles During Initiation of Radiata Pine Somatic Embryogenesis

Climate change will inevitably lead to environmental variations, thus plant drought tolerance will be a determinant factor in the success of plantations and natural forestry recovery. Some metabolites, such as soluble carbohydrates and amino acids, have been described as being the key to both embryogenesis efficiency and abiotic stress response, contributing to phenotypic plasticity and the adaptive capacity of plants. For this reason, our main objectives were to evaluate if the temperature during embryonal mass initiation in radiata pine was critical to the success of somatic embryogenesis, to alter the morphological and ultrastructural organization of embryonal masses at cellular level and to modify the carbohydrate, protein, or amino acid contents. The first SE initiation experiments were carried out at moderate and high temperatures for periods of different durations prior to transfer to the control temperature of 23°C. Cultures initiated at moderate temperatures (30°C, 4 weeks and 40°C, 4 days) showed significantly lower initiation and proliferation rates than those at the control temperature or pulse treatment at high temperatures (50°C, 5 min). No significant differences were observed either for the percentage of embryogenic cell lines that produced somatic embryos, or for the number of somatic embryos per gram of embryonal mass. Based on the results from the first experiments, initiation was carried out at 40°C 4 h; 50°C, 30 min; and a pulse treatment of 60°C, 5 min. No significant differences were found for the initiation or number of established lines or for the maturation of somatic embryos. However, large morphological differences were observed in the mature somatic embryos. At the same time, changes observed at cellular level suggested that strong heat shock treatments may trigger the programmed cell death of embryogenic cells, leading to an early loss of embryogenic potential, and the formation of supernumerary suspensor cells. Finally, among all the differences observed in the metabolic profile, it is worth highlighting the accumulation of tyrosine and isoleucine, both amino acids involved in the synthesis of abiotic stress response-related secondary metabolites

Nivel de conocimientos en los manejos preoperatorios en pacientes con enfermedades sistémicas

Objective: To determine the knowledge on preoperative management of patients with systemic risk diseases in students of the UAO (Dental Care Unit) UNIANDES, specifically in the semesters of Tenth, Ninth parallel "A" and "B" in the academic period May-September 2020. Method: Descriptive observational study in a population of 78 students. Results: 60.25% of students consider that the university does not provide them with the necessary knowledge to be able to identify a systemically compromised patient. Conclusion: It can be concluded that this data acquires a degree of fallacy, due to the fact that when reviewing the curricular mesh the Universidad Regional Autónoma de los Andes does contemplate subjects that deal with the knowledge and identification of such patients in different diseases.Objetivo:  Determinar el conocimiento sobre el manejo preoperatorio de pacientes con enfermedades sistémicas de riesgo en los estudiantes de la UAO (Unidad de Atención Odontológica) UNIANDES, concretamente en los semestres de Décimo, Noveno paralelos “A” y “B” en el período académico mayo- septiembre 2020. Método: Descriptiva observacional en una población de 78 estudiantes. Resultados: El 60.25% de estudiantes consideran que la universidad no les aporta el conocimiento necesario para poder identificar a un paciente sistémicamente comprometido. Conclusión:  se puede concluir que este dato adquiere un grado de falacia, debido a que al revisar la malla curricular la Universidad Regional Autónoma de los Andes sí contempla materias que tratan el conocimiento y la identificación de dichos pacientes en diferentes enfermedades