4,651 research outputs found
Zero-thickness interface model with chemical degradation by acid attack
Carbon dioxide (CO2) storage in abandoned oil/gas reservoirs is considered a viable alternative to reduce greenhouse gas emissions to the atmosphere. An important element of the risk associated with long-term CO2 storage is the loss of integrity of the cement seals of the abandoned wells in the reservoir. Among others, one possible cause of loss of integrity is the degradation of the oil-well cement due to the acid attack of the carbonated brine in the reservoir. In previous studies, the authors have developed a diffusion-reaction model for simulating this degradation process. In order to study possible coupled Chemo-Mechanical (CM) mechanisms, this model will be coupled with an existing mechanical model. For this purpose, in this paper, an existing constitutive law for zero-thickness interface, based on the theory of elasto-plasticity with concepts of fracture mechanics, is modified to incorporate the effect of chemical degradation on the mechanical strength parameters. Preliminary results obtained with this new constitutive law are presented, in order to illustrate the main aspects of the proposed constitutive law, as well as a possible C-M degradation mechanism that should be considered in the long-term safety assessment of CO2 geological storage projects
TBL1 is required for the mesenchymal phenotype of transformed breast cancer cells
The epithelial-to-mesenchymal transition (EMT) and its reversion (MET) are related to tumor cell dissemination and migration, tumor circulating cell generation, cancer stem cells, chemoresistance, and metastasis formation. To identify chromatin and epigenetic factors possibly involved in the process of EMT, we compare the levels of expression of epigenetic genes in a transformed human breast epithelial cell line (HMEC-RAS) versus a stable clone of the same cell line expressing the EMT master regulator ZEB1 (HMEC-RAS-ZEB1). One of the factors strongly induced in the HMEC-RAS-ZEB1 cells was Transducin beta-like 1 (TBL1), a component of the NCoR complex, which has both corepressor and coactivator activities. We show that TBL1 interacts with ZEB1 and that both factors cooperate to repress the promoter of the epithelial gene E-cadherin (CDH1) and to autoactivate the ZEB1 promoter. Consistent with its central role, TBL1 is required for mesenchymal phenotypes of transformed breast epithelial and breast cancer cell lines of the claudin-low subtype. Importantly, a high expression of the TBL1 gene correlates with poor prognosis and increased proportion of metastasis in breast cancer patients, indicating that the level of TBL1 expression can be used as a prognostic marker.Ministerio de Economía y Competitividad BFU2014-53543-P, BFU2017-85420-RJunta de Andalucía BIO-32
Next-to-eikonal corrections in the CGC: gluon production and spin asymmetries in pA collisions
We present a new method to systematically include corrections to the eikonal
approximation in the background field formalism. Specifically, we calculate the
subleading, power-suppressed corrections due to the finite width of the target
or the finite energy of the projectile. Such power-suppressed corrections
involve Wilson lines decorated by gradients of the background field - thus
related to the density - of the target. The method is of generic applicability.
As a first example, we study single inclusive gluon production in pA
collisions, and various related spin asymmetries, beyond the eikonal accuracy.Comment: 34 pages, new reference added, some typos correcte
Electricity contract price prediction using genetic programming with functional blocks
The prediction of the prices of the contracts in non-regulated electricenergy markets is the key for the market agents to make strategic business and operational decisions. The average prices of the contracts sold in the Colombian electric energy market are predicted in this study by means of a modified genetic programming algorithm. The developed model is capable of capturing the intrinsic dynamics of the prices and the price predictions for the upcoming months with a more accurate precision than the ARIMA and DAN2 models for prediction horizons of 12 and 14 months, as they have been reported in the literature.La predicción de los precios de los contratos en los mercados energéticos desregularizados es la clave para la toma de decisiones estratégicas de negocio y operativas por los agentes del mercado. En este trabajo se predicen los precios promedio de los contratos vendidos en el mercado eléctrico colombiano, utilizando un algoritmo de programación genética modificado. El modelo desarrollado es capaz de capturar la dinámica intrínseca de los precios y las predicciones de precios para los próximos meses con mayor precisión que los modelos ARIMA y DAN2 para horizontes de predicción de 12 y 24 meses, reportados en la literatura
Medium-induced soft gluon radiation in DIS
We study color coherence effects on the medium-induced soft gluon radiation
off an asymptotic quark hit by a virtual photon traversing a hot and dense QCD
medium. The transverse momentum spectrum of the emitted gluon is computed at
1st order in the opacity expansion. The interference effects between the
initial and final state radiation modify the soft gluon spectrum when a finite
angle between the incoming and outgoing quarks is considered, presenting a soft
divergence. We comment on possible implications on observables in eA
collisions.Comment: 4 pages, 2 figure, Proceedings of DIS 2012, Bonn, German
Marcela Gómez Sollano: una niña admirada y admirable
En el Teetetes o de la Ciencia, Sócrates le dice a suamigo Teetetes que la turbación es un sentimiento propiodel filósofo, «y el primero que ha dicho que Iris era hijade Taumas, no explicó mal la genealogía» (Platón, 1979,305). Taumas viene del verbo griego que significa asombrarse. Recuérdese que Iris lo sabe todo, y representala ciencia y la filosofía. La capacidad de asombro está,pues, en el origen de todo conocimiento científico y todaindagación filosófica. Iris lleva siempre un ánfora llenade agua de la laguna Estigia, y quien bebe de ella quedasin memoria. Un poco después, en este mismo diálogo,Sócrates establece varios niveles de conocedores: el quesabe porque tiene recuerdos de ello en el alma (paraSócrates y su discípulo Platón, conocer era recordar); elque sabe y confunde lo que sabe con lo que no sabe ycon lo que no ha dejado en él huella alguna; el que sabe yse mantiene en su tesis, y el que no sabe y cree que sabe(Platón, 1977, p. 927)
Centromere fission, not telomere erosion, triggers chromosomal instability in human carcinomas
The majority of sporadic carcinomas suffer from a kind of genetic instability in which chromosome number changes occur together with segmental defects. This means that changes involving intact chromosomes accompany breakage-induced alterations. Whereas the causes of aneuploidy are described in detail, the origins of chromosome breakage in sporadic carcinomas remain disputed. The three main pathways of chromosomal instability (CIN) proposed until now (random breakage, telomere fusion and centromere fission) are largely based on animal models and in vitro experiments, and recent studies revealed several discrepancies between animal models and human cancer. Here, we discuss how the experimental systems translate to human carcinomas and compare the theoretical breakage products to data from patient material and cancer cell lines. The majority of chromosomal defects in human carcinomas comprises pericentromeric breaks that are captured by healthy telomeres, and only a minor proportion of chromosome fusions can be attributed to telomere erosion or random breakage. Centromere fission, not telomere erosion, is therefore the most probably trigger of CIN and early carcinogenesis. Similar centromere–telomere fusions might drive a subset of congenital defects and evolutionary chromosome changes
“Green” Quantum Dots: Basics, Green Synthesis, and Nanotechnological Applications
Nanotechnological development of new materials involves the discovery or design of materials at small length scales with controlled physical and chemical properties than can be tuned or modified in function of their applications. One of the most suitable examples of nanoparticles used for this purpose are quantum dots, a type of colloidal fluorescent semiconducting nanocrystalline material that has the possibility, due to its unique optical and electronic properties, to be used in numerous technological applications such as biosensing, in vivo imaging techniques, photovoltaics, nanomedicine, molecular pathology, and drug delivery. Thus, there are almost endless possibilities for quantum dots materials. In spite of the fast advance in the search of quantum dots with better nanomaterial performance, environmentally benign and sustainable production is still lacking. Although the use of these materials is developing promptly, there is increasing concern that these materials might pose potential risks to human health. Herein, we discuss principal properties of quantum dots, including their functional architecture and toxicity, and review the main studies about “green” quantum dots synthesis to be aligned with green nanotechnology approach for nontoxic, cleaner, safer, and more responsible processes. The organometallic colloidal synthesis and the aqueous colloidal synthesis, as well as their drawbacks and benefits, are conferred. Recent advances in technological and biological quantum dots–based applications are also discussed in this chapter
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