536 research outputs found
Gene Regulatory Networks controlling Arabidopsis Root Stem Cells
Conferencia sobre aproximaciones sistémicas al conocimiento biológicoGene Regulatory Networks controlling Arabidopsis Root Stem Cells
Identifying the transcription factors (TFs) and associated regulatory processes involved in stem
cell regulation is key for understanding the initiation and growth of tissues and organs. Although
many TFs have been described in the Arabidopsis root stem cells, a comprehensive view of the
transcriptional signature of the stem cells is lacking. We used a systems biology approach to
predict interactions among the genes involved in stem cell identity and maintenance.
We first transcriptionally profiled four stem cell populations and developed a gene regulatory
network (GRN) inference algorithm, GENIST, which combines spatial and temporal transcriptomic
datasets to identify important TFs and infer gene-to-gene interactions. Our approach resulted in a
map of gene interactions that orchestrates the transcriptional regulation of stem cells. In addition
to linking known stem cell factors, our resulting GRNs predicted additional TFs involved in stem
cell identity and maintenance. We mathematically modeled and experimentally validated some of
our predicted transcription factors, which confirmed the robustness of our algorithm and our
resulting networks. Our approach resulted in the finding of a factor, PERIANTHIA (PAN), which
may play an important role in stem cell maintenance and QC function.
We then developed an imaging system to perform in vivo, long-term imaging experiments that will
be used to understand the dynamics of the regulatory interactions between PAN and its
downstream TFs in a cell-specific manner. For this, we designed and 3-D printed a Multi-sample
Arabidopsis Growth and Imaging Chamber (MAGIC) that provides near-physiological imaging
conditions and allows high-throughput time-course imaging experiments in the ZEISS Lightsheet
Z.1. We showed MAGIC’s imaging capabilities by following cell divisions, as an indicator of plant
growth and development, over prolonged time periods, and demonstrated that plants imaged with
our chamber undergo cell divisions for >16 times longer than those with the glass capillary
system supplied by the ZEISS Z1. Future in vivo observations of the expression of PAN and its
predicted downstream factors will be key to refine our model predictions and obtain information
about the dynamics of the regulatory processes.
Our systems biology approach illustrates the strength of integrating computational and
technological tools into the experimental approaches to solve key biological questions. We
anticipate that our algorithm and our approach can be applied to solve similar problems in a
diverse number of systems, which can result in unsupervised predictions of gene functions and
gene candidates.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Política presupuestaria y elecciones
El carácter cíclico de las elecciones ha originado el estudio del efecto que esta periodicidad puede ejercer sobre la política fiscal de los gobiernos, surgiendo
así el análisis del Ciclo Político Presupuestario (CPP). El objetivo de este trabajo es realizar un repaso de la literatura existente sobre los cambios en la política presupuestaria con origen en las elecciones, motivados principalmente por un comportamiento oportunista de los gobernantes. Además se analizan cuestiones como los determinantes de la magnitud de los ciclos o su efecto sobre la reelección
de los gobiernos. La literatura muestra que, además de incrementos en el gasto antes de las elecciones o recortes de impuestos, algunos gobernantes cambian la composición
del gasto preelectoral con el objetivo de conseguir más votos. Sin embargo, este tipo de comportamientos oportunistas no siempre se traduce en una recompensa para los gobernantes. Asimismo, cabe destacar que factores tales como el nivel de desarrollo del país, el nivel de transparencia fiscal o la libertad de los medios de comunicación son algunos de los factores que pueden influir en el tamaño de los CPP, siendo fundamentalmente en las democracias más recientes, en donde la falta de información
por parte de los votantes, hace que se produzcan este tipo de comportamientos oportunistas.The cyclical nature of elections has aroused interest in how the electoral calendar affects government fiscal policy, and has motivated analysis of the Political Budget Cycle (PBC). The aim of this paper is to provide a literature review, and to develop a database
gathering the most relevant results on changes in fiscal policy originated by elections, primarily motivated by governments’ opportunistic behaviour. We also analyse issues such as what determines cycle magnitude or its effect on the probability of governments’
reelection.
The literature shows that in addition to spending increases or tax cuts before elections, some governments change the composition of pre-election spending in an attempt to win more votes. However, this type of opportunistic behavior does not always
bring rewards. The literature also reports that level of development of the country, level of fiscal transparency, and media freedom are some of the factors that can influence
the length of the PBC. It is mainly in emerging democracies where the lack of information
made available to voters leads to such opportunistic behaviour on the part of the government
Indigenous Knowledge in Disaster Risk Reduction
The importance of indigenous knowledge in reducing risk from disasters and natural calamities has been widely discussed in the social sciences by scholars arguing for integrative frameworks and participatory processes. This type of knowledge is vital for archipelagic developing countries, such as the Philippines, situated in a geographical area exposed to natural hazards. However, despite its potential contribution to disaster prevention, mitigation, response, rehabilitation and recovery, along with possible combination strategies with western scientific knowledge towards reducing vulnerability and disaster risk management, the literature on the integration of specific communities' indigenous knowledgebased disaster preparedness and adaptation is still limited. The novel contribution of this article is in the discussion of the unique indigenous knowledgeidentified in the cases of San Miguel Island, Camotes Island and Alabat Island, which is utilized even up to the present. Particularly, this study identifies substantial aspects of indigenous knowledge that contribute to disaster risk reduction in the three selected cases. Findings reveal myriad indigenous knowledge pertaining to intensity, height, direction and movement of ocean waves; intensity of winds; sudden surfacing of deep-sea creatures and unease of animals; different patterns of clouds, darkening of skies and foggy horizons, among others. In closely examining indigenous knowledge, this study sheds new light by providing meaningful insights for its contribution to disaster preparedness
Analysis of Physical Conditions in Herbig-Haro Objects
Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2016, Tutora: María Rosario Isabel López HermosoThe aim of this work is to search optical spectra of Herbig-Haro objects in Taurus
star-forming region and analyse it to make a diagnosis on their physical conditions. We study the
degree of excitation, tracers of electron density, electron temperature and degree of ionization that
are properties which are studied by the analysis on the forbidden emission lines. From a total of 57
catalogued objects, the lines of a sample of 30 knots are presented. It is obtained a range on electron
temperature from 0:9 x 104K and > 1:5 x 104K, an average electron density of 2:5 x 10 3cm -3 and
a minimum electron excitation of 15
In Situ Raman Characterization of SOFC Materials in Operational Conditions: A Doped Ceria Study
[EN] The particular operational conditions of electrochemical cells make the simultaneous characterization of both structural and transport properties challenging. The rapidity and flexibility of the acquisition of Raman spectra places this technique as a good candidate to measure operating properties and changes. Raman spectroscopy has been applied to well-known lanthanide ceria materials and the structural dependence on the dopant has been extracted. The evolution of Pr-doped ceria with temperature has been recorded by means of a commercial cell showing a clear increment in oxygen vacancies concentration. To elucidate the changes undergone by the electrolyte or membrane material in cell operation, the detailed construction of a homemade Raman cell is reported. The cell can be electrified, sealed and different gases can be fed into the cell chambers, so that the material behavior in the reaction surface and species evolved can be tracked. The results show that the Raman technique is a feasible and rather simple experimental option for operating characterization of solid-state electrochemical cell materials, although the treatment of the extracted data is not straightforward.This research was funded by the Spanish Government (IJCI-2017-34110, RTI2018-102161 and SEV-2016-0683 grants).Solís, C.; Balaguer Ramirez, M.; Serra Alfaro, JM. (2020). In Situ Raman Characterization of SOFC Materials in Operational Conditions: A Doped Ceria Study. Membranes. 10(7):1-16. https://doi.org/10.3390/membranes10070148S116107Maher, R. C., Duboviks, V., Offer, G. J., Kishimoto, M., Brandon, N. P., & Cohen, L. F. (2013). Raman Spectroscopy of Solid Oxide Fuel Cells: Technique Overview and Application to Carbon Deposition Analysis. Fuel Cells, 13(4), 455-469. doi:10.1002/fuce.201200173Cheng, Z., Wang, J.-H., Choi, Y., Yang, L., Lin, M. C., & Liu, M. (2011). From Ni-YSZ to sulfur-tolerant anode materials for SOFCs: electrochemical behavior, in situ characterization, modeling, and future perspectives. Energy & Environmental Science, 4(11), 4380. doi:10.1039/c1ee01758fLiu, M., Lynch, M. E., Blinn, K., Alamgir, F. M., & Choi, Y. (2011). Rational SOFC material design: new advances and tools. Materials Today, 14(11), 534-546. doi:10.1016/s1369-7021(11)70279-6Maher, R. C., Shearing, P. R., Brightman, E., Brett, D. J. L., Brandon, N. P., & Cohen, L. F. (2015). Reduction Dynamics of Doped Ceria, Nickel Oxide, and Cermet Composites Probed Using In Situ Raman Spectroscopy. Advanced Science, 3(1), 1500146. doi:10.1002/advs.201500146Laguna-Bercero, M. A., & Orera, V. M. (2011). Micro-spectroscopic study of the degradation of scandia and ceria stabilized zirconia electrolytes in solid oxide electrolysis cells. International Journal of Hydrogen Energy, 36(20), 13051-13058. doi:10.1016/j.ijhydene.2011.07.082Brett, D. J. L., Kucernak, A. R., Aguiar, P., Atkins, S. C., Brandon, N. P., Clague, R., … Vesovic, V. (2010). What Happens Inside a Fuel Cell? Developing an Experimental Functional Map of Fuel Cell Performance. ChemPhysChem, 11(13), 2714-2731. doi:10.1002/cphc.201000487Sheppard, N. (1982). Recent developments in the vibrational spectroscopies (infrared, Raman, electron energy loss etc.) as applied to the structural analysis of species chemisorbed on metal surfaces. Journal of Molecular Structure, 80, 163-174. doi:10.1016/0022-2860(82)87225-6Balaguer, M., Solís, C., & Serra, J. M. (2012). Structural–Transport Properties Relationships on Ce1–xLnxO2−δ System (Ln = Gd, La, Tb, Pr, Eu, Er, Yb, Nd) and Effect of Cobalt Addition. The Journal of Physical Chemistry C, 116(14), 7975-7982. doi:10.1021/jp211594dMogensen, M. (2000). Physical, chemical and electrochemical properties of pure and doped ceria. Solid State Ionics, 129(1-4), 63-94. doi:10.1016/s0167-2738(99)00318-5Balaguer, M., García-Fayos, J., Solís, C., & Serra, J. M. (2013). Fast Oxygen Separation Through SO2- and CO2-Stable Dual-Phase Membrane Based on NiFe2O4–Ce0.8Tb0.2O2-δ. Chemistry of Materials, 25(24), 4986-4993. doi:10.1021/cm4034963Degen, T., Sadki, M., Bron, E., König, U., & Nénert, G. (2014). The HighScore suite. Powder Diffraction, 29(S2), S13-S18. doi:10.1017/s0885715614000840Rietveld, H. M. (1969). A profile refinement method for nuclear and magnetic structures. Journal of Applied Crystallography, 2(2), 65-71. doi:10.1107/s0021889869006558Rodríguez-Carvajal, J. (1993). Recent advances in magnetic structure determination by neutron powder diffraction. Physica B: Condensed Matter, 192(1-2), 55-69. doi:10.1016/0921-4526(93)90108-iShannon, R. D. (1976). Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. 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D., & Weber, W. H. (1994). Raman and x‐ray studies of Ce1−xRExO2−y, where RE=La, Pr, Nd, Eu, Gd, and Tb. Journal of Applied Physics, 76(4), 2435-2441. doi:10.1063/1.357593Esther Jeyanthi, C., Siddheswaran, R., Kumar, P., Siva Shankar, V., & Rajarajan, K. (2014). Structural and spectroscopic studies of rare earths doped ceria (RELa,Sc,Yb:CeO2) nanopowders. Ceramics International, 40(6), 8599-8605. doi:10.1016/j.ceramint.2014.01.076Shirbhate, S., Nayyar, R. N., Ojha, P. K., Yadav, A. K., & Acharya, S. (2019). Exploration of Atomic Scale Changes during Oxygen Vacancy Dissociation Mechanism in Nanostructure Co-Doped Ceria: As Electrolytes for IT-SOFC. Journal of The Electrochemical Society, 166(8), F544-F554. doi:10.1149/2.1191908jesArtini, C. (2018). Rare-Earth-Doped Ceria Systems and Their Performance as Solid Electrolytes: A Puzzling Tangle of Structural Issues at the Average and Local Scale. Inorganic Chemistry, 57(21), 13047-13062. doi:10.1021/acs.inorgchem.8b02131Spanier, J. 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La eficiencia de los municipios españoles durante el período de crisis
En este trabajo se analiza la
eficiencia en costes de los
gobiernos locales españoles
durante el período de la crisis
económica (2008-2012). Los
resultados indican una mejora
general de la eficiencia a lo
largo del período, es decir,
los gobiernos locales son más
eficientes en tiempos de crisis.
Asimismo, el análisis muestra
que los niveles de eficiencia
varían en función del tamaño de
los gobiernos locales, siendo los
municipios de mayor tamaño los
más eficientes
Output complexity, environmental conditions, and the efficiency of municipalities
Over the last few years, many studies have analyzed the efficiency of local governments in different countries. An accurate definition of their output bundles—i.e., the services and facilities they provide to their constituencies—is essential to this research. However, several difficulties emerge in this task. First, since in most cases the law only establishes the minimum amount of services and facilities to provide, it may well be the case that some municipalities go beyond the legal minimum and, consequently, might have an uncertain effect on efficiency when compared to other municipalities which stick to the legal minimum. Second, municipalities face very different environmental conditions, which raises some doubts about the plausibility of an unconditional analysis. This study tackles these problems by proposing an analysis in which the efficiency of municipalities is evaluated after splitting them into clusters according to various criteria (output mix, environmental conditions, level of powers). We perform our estimations using order-m frontiers, given their robustness to outliers and immunity to the curse of dimensionality. We provide an application to Spanish municipalities, and results show that both output mix and, more especially, environmental conditions, should be controlled for, since efficiency differences between municipalities in different groups are notable
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