WKB formalism and a lower limit for the energy eigenstates of bound states for some potentials

In the present work the conditions appearing in the WKB approximation formalism of quantum mechanics are analyzed. It is shown that, in general, a careful definition of an approximation method requires the introduction of two length parameters, one of them always considered in the text books on quantum mechanics, whereas the second one is usually neglected. Afterwards we define a particular family of potentials and prove, resorting to the aforementioned length parameters, that we may find an energy which is a lower bound to the ground energy of the system. The idea is applied to the case of a harmonic oscillator and also to a particle freely falling in a homogeneous gravitational field, and in both cases the consistency of our method is corroborated. This approach, together with the Rayleigh--Ritz formalism, allows us to define an energy interval in which the ground energy of any potential, belonging to our family, must lie.Comment: Accepted in Modern Physics Letters

Bouncing Cosmologies in Palatini f(R)f(R) Gravity

We consider the early time cosmology of f(R) theories in Palatini formalism and study the conditions that guarantee the existence of homogeneous and isotropic models that avoid the Big Bang singularity. We show that for such models the Big Bang singularity can be replaced by a cosmic bounce without violating any energy condition. In fact, the bounce is possible even for pressureless dust. We give a characterization of such models and discuss their dynamics in the region near the bounce. We also find that power-law lagrangians with a finite number of terms may lead to non-singular universes, which contrasts with the infinite-series Palatini f(R) lagrangian that one needs to fully capture the effective dynamics of Loop Quantum Cosmology. We argue that these models could also avoid the formation of singularities during stellar gravitational collapse.Comment: 8 pages, 4 figures; added references and a short comment in sec.I

Isotropic and Anisotropic Bouncing Cosmologies in Palatini Gravity

We study isotropic and anisotropic (Bianchi I) cosmologies in Palatini $f(R)$ and $f(R,R_{\mu\nu}R^{\mu\nu})$ theories of gravity and consider the existence of non-singular bouncing solutions in the early universe. We find that all $f(R)$ models with isotropic bouncing solutions develop shear singularities in the anisotropic case. On the contrary, the simple quadratic model $R+a R^2/R_P+R_{\mu\nu}R^{\mu\nu}/R_P$ exhibits regular bouncing solutions in both isotropic and anisotropic cases for a wide range of equations of state, including dust (for $a<0$) and radiation (for arbitrary $a$). It thus represents a purely gravitational solution to the big bang singularity and anisotropy problems of general relativity without the need for exotic ($w>1$) sources of matter/energy.Comment: 25 pages, 7 figure

Luces y sombras del análisis de expresión génica utilizando microarrays. Un ejemplo en cerdo ibérico

Ponencia publicada en ITEA, vol.104La tecnología de los microarrays de expresión es la herramienta ideal para el estudio de patrones de expresión de miles de genes de forma simultánea. Sin embargo existe gran variabilidad de resultados atribuible a los aspectos técnicos y de análisis estadístico. En este trabajo presentamos algunos de los problemas surgidos en el estudio de las diferencias de expresión en hígado de cerdos ibéricos para los tratamientos sexo y alimentación empleando microarrays de Affymetrix. Los datos de expresión normalizados fueron analizados siguiendo dos aproximaciones de la metodología de los modelos mixtos. Para ambos tratamientos las diferencias de expresión detectadas fueron dependientes del modelo de análisis y solo un pequeño número de genes diferencialmente expresados fueron coincidentes en ambas estrategias estadísticas. Algunas de estas diferencias de expresión fueron validadas por PCR cuantitativa. Además identificamos errores de diseño y falta de anotación de las sondas del array. Los resultados de este estudio nos han permitido detectar diferencias de expresión de algunos genes de interés, pero también remarcan la necesidad de realizar estudios complementarios que confirmen las diferencias de expresión reveladas a través de la tecnología de los microarraysLights and darkness of gene expression analysis using microarrays: an example in Iberian pigs Expression microarray technology is the ideal tool for the study of thousands of gene expression patterns simultaneously. However there is a great variability of results attributed to technical and statistical analysis aspects. In this work we present several of the arisen problems of a differential expression study in liver of Iberian pigs under the treatments sex and feeding level using Affymetrix microarray. Normalized expression data were analyzed following two approaches of the mixed model methodology. In both treatments the detected differential expressions were dependent of the statistical model and just a small number of genes were coincident between both statistical strategies. Some of the expression differences were confirmed by quantitative PCR. Besides, we have identified design mistakes and missing annotation of the array probes. The results of this study have allowed us to detect differential expression of interesting genes, but it pointed out the necessity of carrying out complementary studies in order to confirm the differential expressions revealed using microarrays technology

A multiscale material model for metallic powder compaction during hot isostatic pressing

The prediction of the distortions during Near-Net-Shape Hot Isostatic Pressing (NNS-HIP) is an intrinsic multiscale problem where the local interactions among particles determine the macroscopic distortions taking place during the sintering and densification of a component. In this work, a multiscale approach is proposed to solve this problem. In particular, a viscoplastic constitutive model capable of predicting macroscopic contractions during a HIP process with high accuracy has been developed, implemented and validated. The macroscopic model incorporates the mechanical behaviour predicted at the meso-scale by means of multiple-particle finite element models (MP-FEM) of an agglomerate of powder particles. The model is validated through the prediction of distortions during HIP of a full scale industrial case. It is concluded that adding the microscopic information of the HIP process to simulate the contractions at the macroscopic level results in a considerable improvement of the accuracy of the predictions

The role of platelets and neutrophil extracellular traps (NETs) in sepsis: A comprehensive literature review

Sepsis is defined as "an organic dysfunction secondary to the dysregulated response of the patient to an infection." This concept only reveals the tip of the iceberg, the clinical expression of organic failures, without understanding their basis, which is currently explained by cellular and molecular phenomena. Neutrophils are crucial pillars of early innate immune responses, and their fundamental function is phagocytosis. Additionally, neutrophils can degranulate upon activation, releasing various antimicrobial enzymes and pro-inflammatory cytokines, and form neutrophil extracellular traps (NETs), whose purpose is to trap pathogens by releasing their "sticky" nuclear content; the presence of activated platelets amplifies this phenomenon. NETosis is a beneficial process; however, deregulated, it can be detrimental, inducing "immunothrombosis" and compromising the microcirculation, thereby increasing the clinical severity of sepsis. The purpose of this review is to clearly describe the pathophysiological role therapeutic target of NETs, their interaction with platelets in sepsis, and their potential as therapeutic targets, since it has been shown that a therapeutic approach aimed at curbing NETs would be beneficial

Somatostatin subtype-2 receptor-targeted metal-based anticancer complexes

Conjugates of a dicarba analogue of octreotide, a potent somatostatin agonist whose receptors are overexpressed on tumor cells, with [PtCl 2(dap)] (dap = 1-(carboxylic acid)-1,2-diaminoethane) (3), [(η 6-bip)Os(4-CO 2-pico)Cl] (bip = biphenyl, pico = picolinate) (4), [(η 6-p-cym)RuCl(dap)] + (p-cym = p-cymene) (5), and [(η 6-p-cym)RuCl(imidazole-CO 2H)(PPh 3)] + (6), were synthesized by using a solid-phase approach. Conjugates 3-5 readily underwent hydrolysis and DNA binding, whereas conjugate 6 was inert to ligand substitution. NMR spectroscopy and molecular dynamics calculations showed that conjugate formation does not perturb the overall peptide structure. Only 6 exhibited antiproliferative activity in human tumor cells (IC 50 = 63 ± 2 μ in MCF-7 cells and IC 50 = 26 ± 3 μ in DU-145 cells) with active participation of somatostatin receptors in cellular uptake. Similar cytotoxic activity was found in a normal cell line (IC 50 = 45 ± 2.6 μ in CHO cells), which can be attributed to a similar level of expression of somatostatin subtype-2 receptor. These studies provide new insights into the effect of receptor-binding peptide conjugation on the activity of metal-based anticancer drugs, and demonstrate the potential of such hybrid compounds to target tumor cells specifically. © 2012 American Chemical Society

Genetic Evidence for a Tacaribe Serocomplex Virus, Mexico

We isolated arenavirus RNA from white-toothed woodrats (Neotoma leucodon) captured in a region of Mexico in which woodrats are food for humans. Analyses of nucleotide and amino acid sequence data indicated that the woodrats were infected with a novel Tacaribe serocomplex virus, proposed name Real de Catorce virus

Variability of the bond and mechanical properties of self-compacting concrete

This main objective of this research is to evaluate the variability of the mechanical properties (compressive strength, modulus of elasticity and tensile strength) and bond strength of the self-compacting concrete (SCC), with 50 MPa compressive strength at 28 days, varying the maximum aggregate size and the SCC fluidity. The tests were made in 15 x 30 cm concrete cylinders and in beams standardized by Rilem-Ceb-Fib (1973). In agreement with the obtained results, can be concluded that the variability of the self-compacting concrete is small for the modulus of elasticity and for the compressive strength, but the tensile strength presented a significant variability due to the failure mode. About the bond strength, the variability was small showing that the self-compacting concrete is reliable and possesses great potential for use in the civil construction.Peer ReviewedPostprint (published version