1,011 research outputs found
Protein folding and the robustness of cells
The intricate intracellular infrastructure of all known life forms is based on proteins. The folded shape of a protein determines both the protein’s function and the set of molecules it will bind to. This tight coupling between a protein’s function and its interconnections in the molecular interaction network has consequences for the molecular course of evolution. It is also counter to human engineering approaches. Here we report on a simulation study investigating the impact of random errors in an abstract metabolic network of 500 enzymes. Tight coupling between function and interconnectivity of nodes is compared to the case where these two properties are independent. Our results show that the model system under consideration is more robust if function and interconnection are intertwined. These findings are discussed in the context of nanosystems engineering
Expectations and tensions moments in the thesis tutoring in the Faculty of Education at the Pontifical Catholic University of Peru
[EN] Universities determine degree methods in order to provide options to students to obtain bachelor’s degree in a short term. In the Faculty of Education at the Pontifical Catholic University of Peru (PUCP) there are three ways, one of them, which is the thesis. In this article, we describe the results of a qualitative descriptive study oriented to recognize the expectations on the process of thesis and tensions experienced during the tutoring thesis by graduates of the careers of initial and primary education. We applied a focus group and interviewed a group of graduates of the Faculty of Education licensed in the period 2011-2013. We also analyzed three documents of the faculty, curriculum, faculty handbook and graduate procedures guide. Graduates interviewed recognize that the development of the thesis is difficult, a task that generates tension and in that process, it is requires a counselor who has time, who owns qualities for interactive communication, who possess knowledge of the subject and research methodology. When the counselor does not meet these aspects, it creates tension in counseling. Other tensions are generated because they lacked practical knowledge about research and have few skills to develop it. Expectations focus on the selection of the counselor, research orientation and institutional cooperating conditions in optimal process thesis counseling. This research contributes to the line of research training and had the support of the University.[ES] Las universidades determinan modalidades de titulación a fin de brindar opciones a los estudiantes para que se licencien en el corto plazo. En la Facultad de Educación de la Pontificia Universidad Católica del Perú (PUCP) existen tres modalidades, una de ellas es la tesis. En el presente artículo, describimos los resultados de un estudio descriptivo cualitativo orientado a reconocer las expectativas y tensiones vividas durante la asesoría o tutoría de tesis por los egresados de las carreras de educación inicial y educación primaria. Hemos aplicado un focus group y una entrevista a un grupo de egresados de la Facultad de Educación que se licenciaron en el periodo 2011-2013.También analizamos tres documentos de la Facultad: plan de estudios, reglamento y guía de modalidades de titulación. Los licenciados entrevistados reconocen que la elaboración de la tesis es difícil, constituye una tarea que les genera tensión y que en ese proceso se requiere de un asesor que disponga de tiempo, posea cualidades para la comunicación interactiva y conozca el tema y la metodología de investigación. Cuando el asesor no cumple con estos aspectos, genera tensión en la asesoría. Otras tensiones se generaron porque los estudiantes carecían de conocimiento práctico sobre investigación y pocas habilidades para el desarrollo de la misma. Las expectativas se centran en la selección del asesor, orientación de la investigación y condiciones institucionales que colaboren en un proceso óptimo de asesoría de tesis.Esta investigación aporta a la línea de formación en investigación y contó con el apoyo de la Universidad.Revilla, D. (2017). Expectativas y tensiones en la asesoría de tesis en la Facultad de Educación de la Pontificia Universidad Católica del Perú. REDU. Revista de Docencia Universitaria. 15(1):277-303. doi:10.4995/redu.2017.6057.SWORD27730315
Low-temperature flux growth of sulfates, molybdates, and tungstates of Ca, Sr, and Ba and investigation of doping with Mn 6 +
The growth of undoped and Mn6+-doped molybdates and tungstates of alkali-earth metals and BaSO4 has been investigated. Single crystals were grown by the flux method within the temperature range of 600-475°C, using the ternary NaCl-KCl-CsCl solvent. Sizes of undoped crystals increase within the series tungstates<molybdates<sulfate and, depending on the cation, within the series Ca2+≈Sr2+<Ba2+. The Mn6+ ion tends to be reduced to Mn5+/Mn4+ with time in the chloride solution, but can be partly stabilized by the addition of alkali-metal carbonates or hydroxides. The incorporation of Mn6+ is governed by the coordination of the MnO4 2- tetrahedron in the crystal. No significant doping was found for Ca and Sr compounds and only small amounts of Mn6+ were incorporated into BaMoO4 and BaWO4. Crystals with orthorhombic space group Pnma such as BaSO4 exhibit significantly higher doping levels. The Mn6+ distribution in each crystal varies due to manganese reduction with growth time. Temperature-, time-, and concentration-dependent spectroscopy of BaSO4:Mn6+ was performe
On the absence of acylated anthocyanins in some wild grapevine accessions
Our current research is focused on the anthocyanin composition of female grape accessions, mostly Spanish, preserved at El Encín Germplasm Bank. In 2008, berries of 126 accessions were taken at maturity. After the extraction from grape skins, total anthocyans were determined by spectrophotometry, and the anthocyanin fingerprint of grapes by HPLC, considering the relative amount of 15 anthocyanins. Among those 126 accessions, 23 genotypes (18.25 %) did not present acylated anthocyanins. Thus, those 23 genotypes presented a characteristic anthocyanin fingerprint, similar at a certain extent to that presented by some Rhine basin and Italian grape cultivars, e.g., 'Pinot Noir' and 'Gaglioppo'. Nevertheless, the absence of acylated anthocyanins has not been described in any Spanish grape cultivar. The examination of the anthocyanin fingerprint of wild grapes without acylated anthocyanins reveals that the regulation of the anthocyanin biosynthesis may differ in various wild grape accessions.
Low-temperature liquid phase epitaxy of rare-earth-ion doped KY(WO<sub>4</sub>)<sub>2</sub> thin layers
Cerebral blood flow responses to dorsal and ventral STN DBS correlate with gait and balance responses in Parkinson\u27s disease
Rural Aspirations: Reflections for Development Planning, Design and Localized Effects
In this editorial introduction to the Special Issue “Rural aspirations—Livelihood
decisions and rural development trajectories”, we outline current views on aspirations
and their relevance for development research, projects and approaches. Using
several examples from Africa, we outline how the combination of the different theoretical
perspectives, case studies and regional backgrounds provides deeper insights
about the role of aspirations in shaping rural areas. The distinct entry points of the
‘bottom up’ local aspirations for future lives, the ‘top down’ aspirations as visions
for change, and the process of negotiating between these provide novel insights into
directions for development action as well as for future research in the field of aspirations
in the development arena
The availability and geographic location of open-source food composition data used to estimate micronutrient intakes in sub-Saharan Africa: A scoping review
Background
Estimates of dietary micronutrient intakes rely on food composition data. The nutrient composition of foods varies spatially with potentially large effects on dietary micronutrient intakes. This review assessed the availability and geographic origin of five minerals (calcium, iron, iodine, selenium and zinc) in publicly available food composition tables/databases (FCTs) for use in sub-Saharan Africa (SSA).
Methods
A scoping review was conducted following PRISMA guidelines, in which four databases (MEDLINE, Embase, Global Health and Africa Wide Information) and four online resources were searched to identify published FCTs for use in SSA. Metadata were reviewed to identify the geographic origin of composition values for selected foods.
Results
Nineteen publicly available FCTs were identified, with the highest geographic coverage in Eastern Africa (45% of countries) and lowest coverage in Central Africa (12% of countries). Iodine and selenium were reported in four and six FCTs, respectively, while iron and calcium were included in ≥ 18 FCTs. More than 60% of nutrient values were borrowed from other FCTs. The geographic origin of 22% of mineral values were documented.
Conclusions
Limited local food composition analytical data is available, for estimating mineral intakes of SSA populations, with poor documentation of the data sources and the geographic origins of samples. New data structures and improved metadata are required to capture and report geographic information in publicly available FCTs, and to accommodate a new generation of spatially-resolved food composition data
Assessing the potential of the dart model to discrete return lidar simulation—application to fuel type mapping
Fuel type is one of the key factors for analyzing the potential of fire ignition and propaga-tion in agricultural and forest environments. The increase of three-dimensional datasets provided by active sensors, such as LiDAR (Light Detection and Ranging), has improved the classification of fuel types through empirical modelling. Empirical methods are site and sensor specific while Radiative Transfer Models (RTM) approaches provide broader universality. The aim of this work is to analyze the suitability of Discrete Anisotropic Radiative Transfer (DART) model to replicate low density small-footprint Airborne Laser Scanning (ALS) measurements and subsequent fuel type classification. Field data measured in 104 plots are used as ground truth to simulate LiDAR response based on the sensor and flight characteristics of low-density ALS data captured by the Spanish National Plan for Aerial Orthophotography (PNOA) in two different dates (2011 and 2016). The accuracy assessment of the DART simulations is performed using Spearman rank correlation coefficients between the simulated metrics and the ALS-PNOA ones. The results show that 32% of the computed metrics overpassed a correlation value of 0.80 between simulated and ALS-PNOA metrics in 2011 and 28% in 2016. The highest correlations were related to high height percentiles, canopy variability metrics as for example standard deviation and Rumple diversity index, reaching correlation values over 0.94. Two metric selection approaches and Support Vector Machine classification method with variants were compared to classify fuel types. The best-fitted classification model, trained with the DART simulated sample and validated with ALS-PNOA data, was obtained using Support Vector Machine method with radial kernel. The overall accuracy of the classification after validation was 88% and 91% for the 2011 and 2016 years, respectively. The use of DART demonstrates its value for simulating generalizable 3D data for fuel type classification providing relevant information for forest managers in fire prevention and extinction
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