2,559 research outputs found
Gauge Field Theory in the Infrared Regime
We propose that the low energy behavior of a pure gauge theory can be studied
by simply assuming violation of Lorentz invariance which is implemented through
a deformation of the canonical Poisson brackets of the theory depending on an
infrared scale. The resulting theory is equivalent to a pure gauge theory with
a Chern-Simons like term. It is shown that at low energies this theory can be
identified with three dimensional QCD where the mass of the fermion is related
to the infrared scale.Comment: 4pp, ReVte
Osteogenic effects of simvastatin-loaded mesoporous titania thin films
The use of statins in the field of bone regeneration is under current investigation due to the existing demand for non-toxic anabolic agents capable of enhancing bone formation in cases of substantial loss. Simvastatin, a coenzyme currently prescribed in clinics to inhibit cholesterol biosynthesis, has been proven to promote osteogenic differentiation by stimulating bone formation and inhibiting osteoclasts activity. We present the loading of simvastatin in mesoporous TiO2 thin films toward combining the pro-osteogenic properties of this molecule with the demonstrated bioactivity of titania. TiO2 thin films processing and characterization were carried out, as well as evaluation of MC3T3-E1 pre-osteoblasts viability when directly incubated with different concentrations of simvastatin, followed by the analysis of osteogenic activity promoted by simvastatin upon loading in the thin films. The accessible porosity of 36% quantified on the 95 ± 5 nm thick mesoporous thin films, together with pore diameters of 5.5 nm, necks between pores of 2.8 nm and interpore distances of 12 ± 2 nm allow the loading of the simvastatin molecule, as confirmed by FTIR spectroscopy. Simvastatin was found to promote MC3T3-E1 pre-osteoblasts viability at concentrations ≤0.01 g l−1, with a cytotoxicity threshold of 0.05 g l−1. We additionally found that film loadings with 0.001 g l−1 simvastatin promotes statistically higher MC3T3-E1 pre-osteoblast proliferation whereas a higher concentration of 0.01 g l−1 leads to statistically higher osteogenic activity (ALP synthesis), after 21 days of incubation, as compared to unloaded films. These results demonstrate the potential of simvastatin local administration based on bioactive mesoporous thin films to promote pro-osteogenic properties. By focusing this strategy on the coating of metallic prostheses, the supply of simvastatin to the target tissue can be favored and risks of systemic side effects will be reduced while enhancing the osteointegration of the implants.Fil: Lopez Alvarez, Miriam. Universidad de Vigo; EspañaFil: López Puente, Vanesa. Universidad de Vigo; EspañaFil: Rodriguez Valencia, Cosme. Universidad de Vigo; EspañaFil: Angelome, Paula Cecilia. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Liz Marzan, Luis M. Ikerbasque; EspañaFil: Serra, Julia. Universidad de Vigo; EspañaFil: Pastoriza Santos, Isabel. Universidad de Vigo; EspañaFil: Gonzalez, Pio. Universidad de Vigo; Españ
Criteria for efficient prevention of dissemination and successful eradication of Erwinia amylovora (the cause of fire blight) in Aragón, Spain
Erwinia amylovora was detected on pome fruits in the Aragón region (North-Eastern Spain), in a ca. 5 km radius area located in the mid Jalón river (mid Ebro Valley) in the province of Zaragoza, during 2000‒2003. Eight years have now passed since this pathogen was last detected, without new infections being reported in the
same area. The bases for surveys and rapid eradication performed have been analyzed in detail to understand the reasons for the success in removing fireblight. The results demonstrate that intensive surveillance, risk assessment, plant analyses using accurate identification methods, and, especially, rapid total or selective eradication of infected trees in the plots have been very effective in preventing the generalized spread of fireblight and in delaying economic losses associated with this disease. Eradication and compensation to growers, estimated to cost approx. € 467,000, were clearly counterbalanced by the economic value of apple and pear production in the 2000‒2003 period (approx. € 368 million). Fire blight risk-assessment, using the MARYBLYT system, showed that climatic conditions in the studied area were favourable to infections during the analyzed period (1997‒2006). Molecular characterization of
E. amylovora strains had revealed their homogeneity, suggesting that these fire blight episodes could have been caused by just one inoculum source, supporting the hypothesis that there was a unique introduction of E. amylovora in the studied area. Spatial spread of
E. amylovora to trees was analyzed within six orchards, indicating an aggregated distribution model. This Spanish experience demonstrates the success of scientifically-based prevention methods that lead to the deployment of a fast and strict containment strategy, useful for other Mediterranean areassurveysrisk-assessmentspatial analysisstrain characterizationPublishe
Displasia Epifisaria Hemimélica en rótula: (descripción de un nuevo caso y revisión bibliográfica)
Se describe un nuevo caso de Displasia Epifisaria Hemimélica que
asienta en una legalización muy poco frecuente cual es la rótula. Realizan
una amplia revisión bibliográfica de la literatura mundial y se comentan
las variaciones observadas en cuanto al cuadro clínico, diagnóstico y diagnóstico
diferencial.The authors describe a new case of Dysplasia Epiphysealis
Hemimelica with affectation of the patela. It is a localization very
infrequent.
They have made a review of the literature and analyse the
variations observed as for clinical findings, diagnosis and differential
diagnosis
Estudio de la obesidad y del sobrepeso como factores de riesgo de la prevalencia y severidad del asma en niños de Valencia
[email protected]; [email protected]; [email protected]:
La obesidad y el sobrepeso se han descrito como factores de riesgo asociados a la prevalencia y severidad del asma en niños y adolescentes. El objetivo del estudio ha sido el valorar el papel de la obesidad en el asma infantil.
Ámbito de estudio y sujetos:Estudio realizado en niños y adolescentes entre 8 y 15 años, elegidos por un muestreo aleatorio tipo cluster entre los niños que estudiaban en 80 colegios, el cual representa el 30% de los colegios de la ciudad de Valencia.
Material y métodos:El análisis de los datos se organizó en dos grupos, obesos (aquellos niños en un percentil superior al 85 del Índice de Masa Corporal (kg/m2), tomando como referencia la población española) y no obesos, cuando no cumplian esta condición. Se calcularon la prevalencia de los diferentes parámetros con un intervalo de confianza al 95%, y el riesgo relativo (RR) de los síntomas compatibles con asma entre niños obesos comparándolos con los no obesos.
Resultados: No se obtuvo un riesgo relativo significativo para la obesidad con respecto al asma en aquellos niños por encima del percentil 85. Por otra parte, un incremento en el riesgo en relación con la severidad del asma se observó con la obesidad, principalmente en el percentil 85 (RR = 1,51 de sufrir entre 4-12 ataques de pitos y RR = 1,86 de sufrir más de 12 ataques en niños obesos frente a los no obesos)
Conclusiónes: En este estudio, no identificamos un riesgo más alto de asma entre niños obesos frente a los no obesos, aunque encontramos que hubiera un riesgo más alto de severidad de síntomas asmáticos. En relación con la severidad del asma, observamos un riesgo más alto de ataques de pitos y sibilancias entre los niños obesos en los percentiles 85 y 95 del Indice de Masa Corporal.Background: Obesity and overweight have been described as factors associated with asthma. Our aim was to evaluate the role obesity plays on asthma in children.
Scope and subjects: A study carried out on children and teenagers between 8 and 15 years of age, chosen for a cluster-type random sampling from children who studied in 80 schools, which represents 30% of the schools in the city of Valencia.
Material and Methods: The analysed data was organized into two groups, obese (from the Body Mass Index (Kg/m2)), showing children with a percentile over 85% of the measuring reference for the Spanish population) and non obese, when they did not fulfil this condition. The prevalence of the different parameters studied was calculated by an Interval of Confidence of 95%. The risk was calculated (Relative Risk) from those symptoms compatible with asthma among obese children compared to non obese children.
Results: No significant relative risk (RR) was seen for obesity with regards to asthma in those percentiles of obesity over 85. Otherwise, an increase in the relative risk (RR) regarding the severity of asthma was seen in relation to obesity, mainly in the 85th percentile (RR = 1.51 of suffering between 4-12 wheezing attacks and RR = 1.86 of suffering more than 12 attacks in obese children as opposed to non obese children).
Conclusions:
In this study, we did not identify a higher risk of asthma among obese children than among non obese children, although we did find there was a higher risk of severity of asthmatic symptoms. As far as the severity of the asthma is concerned, we saw a higher risk of wheezing and whistling attacks among obese children with the 85th and the 95th percentiles according to the Body Mass [email protected]; [email protected]; [email protected]
A regulatory cascade involving retinoic acid, Cbfa1, and matrix metalloproteinases is coupled to the development of a process of perichondrial invasion and osteogenic differentiation during bone formation
Tissue-remodeling processes are largely mediated by members of the matrix metalloproteinase (MMP) family of endopeptidases whose expression is strictly controlled both spatially and temporally. In this article, we have examined the molecular mechanisms that could contribute to modulate the expression of MMPs like collagenase-3 and MT1-MMP during bone formation. We have found that all-trans retinoic acid (RA), which usually downregulates MMPs, strongly induces collagenase-3 expression in cultures of embryonic metatarsal cartilage rudiments and in chondrocytic cells. This effect is dose and time dependent, requires the de novo synthesis of proteins, and is mediated by RAR-RXR heterodimers. Analysis of the signal transduction mechanisms underlying the upregulating effect of RA on collagenase-3 expression demonstrated that this factor acts through a signaling pathway involving p38 mitogen-activated protein kinase. RA treatment of chondrocytic cells also induces the production of MT1-MMP, a membrane-bound metalloproteinase essential for skeletal formation, which participates in a proteolytic cascade with collagenase-3. The production of these MMPs is concomitant with the development of an RA-induced differentiation program characterized by formation of a mineralized bone matrix, downregulation of chondrocyte markers like type II collagen, and upregulation of osteoblastic markers such as osteocalcin. These effects are attenuated in metatarsal rudiments in which RA induces the invasion of perichondrial osteogenic cells from the perichondrium into the cartilage rudiment. RA treatment also resulted in the upregulation of Cbfa1, a transcription factor responsible for collagenase-3 and osteocalcin induction in osteoblastic cells. The dynamics of Cbfa1, MMPs, and osteocalcin expression is consistent with the fact that these genes could be part of a regulatory cascade initiated by RA and leading to the induction of Cbfa1, which in turn would upregulate the expression of some of their target genes like collagenase-3 and osteocalcin
La autoeficacia física percibida y el rendimiento deportivo en taekwondo
En el contexto físico-‐deportivo una de las variables de mayor interés tanto para entrenadores, deportistas como para el público en general es el rendimiento deportivo.
Actualmente se tiende a identificar características o habilidades psicológicas que pueden estar interviniendo en dicho rendimiento. Una de las variables psicológicas más estudiadas, en los últimos años, en relación con el rendimiento deportivo es la auto-‐confianza en las propias capacidades físicas
- …