2,651 research outputs found

    Relationship between the main components of the crystalline lens and the anterior chamber depth after cataract formation

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    Producción CientíficaPurpose To assess the relationship between anterior chamber depth (ACD) and lens thickness (LT), as well as its three main components (anterior and posterior cortex and nucleus thickness), in cataractous and non-cataractous eyes, depending on the axial length (AxL). Methods Anterior and posterior cortex and nucleus thickness of the crystalline lens, ACD, and AxL were measured using optical low-coherence reflectometry in cataractous and non-cataractous eyes. They were also classified into hyperopia, emme- tropia, myopia, and high myopia, depending on AxL; thus, eight subgroups were created. A minimum sample size of 44 eyes (of 44 patients) for each group was recruited. Linear models were fitted for the whole sample and each AxL subgroup to assess if there were differences in the relationships between the crystalline lens variables and ACD, including age as a covariate. Results Three hundred seventy cataract patients (237 females, 133 males) and 250 non-cataract controls (180 females, 70 males), aged 70.5 ± 9.4 and 41.9 ± 15.5 years, respectively, were recruited. The mean AxL, ACD, and LT for the cataractous and non-cataractous eyes were 23.90 ± 2.05, 24.11 ± 2.11, 2.64 ± 0.45, and 2.91 ± 0.49, 4.51 ± 0.38, 3.93 ± 0.44 mm, respec- tively. The inverse relationship of LT, anterior and posterior cortex, and nucleus thickness with ACD was not significantly (p ≥ 0.26) different between cataractous and non-cataractous eyes. Further subclassification of the sample depending on AxL showed that the inverse relationship between the posterior cortex and ACD was no longer significant (p > 0.05) for any non-cataractous AxL group. LT, anterior and posterior cortex, and nucleus thickness was not significantly (p ≥ 0.43) different between cataractous and non-cataractous eyes for the whole sample, and all AxL groups after adjusting for age. Conclusions The presence of cataracts does not modify the inverse relationship of the LT, anterior and posterior cortex, and nucleus with ACD. And this relationship does not seem to depend importantly on AxL. Besides, the possible differences in LT, anterior and posterior cortex, and nucleus between cataractous and non-cataractous eyes may not be caused by lens opacification, but possibly by the progressive lens growth due to aging.Ministerio de Economía y Competitividad (Instituto de Salud Carlos III) through Research Projects (RETICS RD16/008/0001)Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL

    Global properties of the spectrum of the Haldane-Shastry spin chain

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    We derive an exact expression for the partition function of the su(m) Haldane-Shastry spin chain, which we use to study the density of levels and the distribution of the spacing between consecutive levels. Our computations show that when the number of sites N is large enough the level density is Gaussian to a very high degree of approximation. More surprisingly, we also find that the nearest-neighbor spacing distribution is not Poissonian, so that this model departs from the typical behavior for an integrable system. We show that the cumulative spacing distribution of the model can be well approximated by a simple functional law involving only three parameters.Comment: RevTeX 4, 7 pages, 4 figures. To appear in Phys. Rev.

    EVO+ Implantable Collamer Lens KS-aquaPORT Location, Stability, and Impact on Quality of Vision and Life

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    Purpose: To determine the longitudinal variation in the KS-aquaPORT central hole location of the phakic EVO+I Implantable Collamer Lens (ICL) (STAAR Surgical) and analyze its influence on visual performance, quality of vision (QoV), and quality of life (QoL). Methods: A prospective study was performed including 36 patients who had EVO+ ICL implantation. The KS-aquaPORT central hole location (Cartesian and polar coordinates) was determined with respect to the pupil center and visual axis. The effect of time (6-month follow-up) on central hole location was analyzed using linear mixed models. The effect of the KS-aquaPORT location on visual performance, QoV, and QoL parameters was assessed with multivariate regression models. Results: With respect to the visual axis, no significant changes in KS-aquaPORT location were found during follow-up. With respect to the pupil center, the X-coordinate and radius of KS-aquaPORT location showed modest, but significant (P ≤ .05) differences between 1-week and 3-month postoperative visits, and between 1-week and 6-month visits. X-coordinate variation was significant (P = .022) between 1-and 6-month visits. With respect to the visual axis, greater KS-aquaPORT decentration was associated with worse visual acuity (X-coordinate: P = .004; radius: P = .006), and inferior decentration with longer xenon-type glare photostress recovery time (P = .021). With respect to the pupil center, a lower radius was associated with better QoV scores (P ≤ .01) and temporal decentration produced higher ring-shaped dysphotopsia (P = .007). Conclusions: EVO+ ICL KS-aquaPORT location appears to be clinically stable up to 6 months postoperatively. A central location of the EVO+ ICL KS-aquaPORT hole is preferred because it allows reduced perception of dysphotopic phenomena that can result in better QoV.This study was supported in part by the Spanish Ministry of Economy and Competitiveness (Instituto de Salud Carlos III) through Research Projects RETICS RD16/008/0001 (Oftared); EM-P was supported by Junta de Castilla y León and European Social Fund (EDU/1100/2017)

    Effect of the EVO+ Visian Phakic Implantable Collamer Lens on Visual Performance and Quality of Vision and Life

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    Purpose: To assess the effect of EVO+ (V5) Visian implantable collamer lens implantation on mesopic visual performance, quality of vision (QoV), and quality of life (QoL). Design: Prospective interventional case series. Methods: Thirty-six eyes of 36 participants who underwent EVO+ implantation for myopia were evaluated preoperatively and at postoperative visits at 1 week and 1, 3, and 6 months. Visual acuity (VA) and mesopic contrast sensitivity (CS) with and without halogen- and xenon-type glare sources were evaluated at each visit. Subjective QoV was assessed with the QoV questionnaire and QoL assessed with the Quality of Life Impact of Refractive Correction (QIRC) questionnaire at each visit. Ring-shaped dysphotopsia was also assessed at each postoperative visit. Linear, cumulative link and logit mixed models were fitted to analyze the effect of the EVO+. Results: Following EVO+ implantation, VA significantly (P ≤ .012) improved at the 4 postoperative visits. Mesopic CS progressively improved at 1, 3, and 6 months postoperatively (P ≤ .012). Halogen glare CS decreased at 1 week and halogen and xenon glare CS improved at 6 months (P ≤ .016). Photostress recovery time after halogen glare improved at 3 and 6 months (P ≤ .004). QoV scores improved at 1 week and 3 and 6 months (P ≤ .001). QIRC scores improved postoperatively (P < .001). Ring-shaped dysphotopsia decreased at 3 and 6 months (P ≤ .007). Conclusions: EVO+ implantation provides good mesopic visual performance, QoV, and QoL during up to 6 months follow-up. Some activities performed under mesopic conditions with glare sources may be affected during the first postoperative week. Ring-shaped dysphotopsia is negligibly bothersome 6 months after surgery.This study was supported in part by the Spanish Ministry of Economy and Competitiveness (Instituto de Salud Carlos III) through Research Projects RETICS RD16/008/0001 (Oftared); EM-P was supported by Junta de Castilla y León and European Social Fund (EDU/1100/2017)

    Tetrazole derivatives as potent immunomodulatory agents in tumor microenvironment

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    Twenty-seven compounds bearing a tetrazole ring as a central unit have been designed, synthetized and biologically evaluated. Studies have been performed in order to compare the effect of tetrazole derivatives bearing amine electron-donor or nitro electron-acceptor groups. The antiproliferative activity has been determined in monoculture studies on tumor cell lines HT-29, A-549, MCF-7 and on non-tumor cell line HEK-293 as well as in co-culture studies (HT-29/THP-1). All the compounds have been studied as PD-L1 (Programmed Death Ligand 1), VEGFR-2 (Vascular Endothelial Growth Factor 2), CD-47 (Cluster of Differentiation 47) and c-Myc inhibitors. The effect on TNF-α secretion has also been determined. Bromoderivatives 23, 24 and chloroderivatives 26, 27 have demonstrated an apoptotic effect on HT-29 cancer cells. Compounds bearing an amine group have shown very promising effects as TME immunomodulatory agents

    Ecological connectivity shapes quasispecies structure of RNA viruses in an Antarctic lake

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    © 2015 John Wiley & Sons Ltd. RNA viruses exist as complex mixtures of genotypes, known as quasispecies, where the evolution potential resides in the whole community of related genotypes. Quasispecies structure and dynamics have been studied in detail for virus infecting animals and plants but remain unexplored for those infecting micro-organisms in environmental samples. We report the first metagenomic study of RNA viruses in an Antarctic lake (Lake Limnopolar, Livingston Island). Similar to low-latitude aquatic environments, this lake harbours an RNA virome dominated by positive single-strand RNA viruses from the order Picornavirales probably infecting micro-organisms. Antarctic picorna-like virus 1 (APLV1), one of the most abundant viruses in the lake, does not incorporate any mutation in the consensus sequence from 2006 to 2010 and shows stable quasispecies with low-complexity indexes. By contrast, APLV2-APLV3 are detected in the lake water exclusively in summer samples and are major constituents of surrounding cyanobacterial mats. Their quasispecies exhibit low complexity in cyanobacterial mat, but their run-off-mediated transfer to the lake results in a remarkable increase of complexity that may reflect the convergence of different viral quasispecies from the catchment area or replication in a more diverse host community. This is the first example of viral quasispecies from natural aquatic ecosystems and points to ecological connectivity as a modulating factor of quasispecies complexity.Spanish Polar Programme and the Spanish Ministry of Economy and Competitiveness (CTM2008-05134-E/ANT and CTM2009-08644-E).Peer Reviewe

    Characterization of corneal structure in keratoconus

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    Producción CientíficaThe increasing volume of patients interested in refractive surgery and the new treatment options available for keratoconus have generated a higher interest in achieving a better characterization of this pathology. The ophthalmic devices for corneal analysis and diagnosis have experienced a rapid development during the past decade with the implementation of technologies such as the Placido-disk corneal topography and the introduction of others such as scanning-slit topography, Scheimpflug photography, and optical coherence tomography, which are able to accurately describe not only the geometry of the anterior corneal surface but also that of the posterior surface, as well as pachymetry and corneal volume. Specifically, anterior and posterior corneal elevation, corneal power, pachymetry maps, and corneal coma-like aberrometry data provide sufficient information for an accurate characterization of the cornea to avoid misleading diagnoses of patients and provide appropriate counseling of refractive surgery candidates

    Propuesta de medio digital periodístico como respuesta ante la creciente desinformación y fake news en medio de una pandemia mundial y una incierta coyuntura política-social en el Perú.

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    La desinformación y las fake news son amenazas que afectan al mundo moderno debido a la instantaneidad de las noticias. La actual pandemia ha evidenciado en el país un gran número de información errada repartida, por ende, vemos una necesidad periodística a cubrir. Esto significa una oportunidad para que nuevos medios periodísticos, quienes deben reinventarse, busquen la manera de insertarse ante un público hiperinformado. Contenidos erróneos son compartidos sin ser correctamente verificados, por lo que es necesario contar con un agente que se encargue de validar, chequear y desmentir información. Asimismo, de analizar afirmaciones, declaraciones de políticos y personalidades de toda índole; así como de contenido compartido por redes sociales y otros canales. El reto del periodismo es converger en nuevas tecnologías, por tanto, es necesario pensar también en plataformas como YouTube debido a las nuevas formas en cómo la audiencia consume información.Disinformation and fake news are threats that affect the modern world due to the instantaneous nature of information. The current pandemic has revealed a large number of fake news distributed in the country, so we see a journalistic need to cover. This represents an opportunity for new journalistic media, who must reinvent themselves, to find a way to insert into a hyperinformed audience. Mistaken content is shared without being properly verified, so it is necessary to have an agent who is in the responsibility of validate, verify and deny information. Also, to analyze affirmations and statements of politicians and personalities of all kinds, such as content shared by social media and other channels. The challenge of journalism is to converge on new technologies. Therefore, it is necessary to also think about platforms like YouTube due to the new ways in how the audience consumes information

    Value, quality, purchasing habits and repurchase intention in B2C: differences between frequent and occasional purchasers

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    Este estudio propone un modelo integrador de la recompra en comercio electrónico (B2C), basado en la teoría de la confirmación de expectativas, tomando como partida el modelo de Bhattacherjee extendido con el modelo de satisfacción Cronin. El modelo de investigación se ha probado con 536 compradores españoles, usando análisis multigrupo. El modelo fue capaz de explicar más del setenta por ciento de la varianza de la intención de recompra. Como resultados, la relación entre la calidad y la satisfacción es no significativa para todos los tipos de consumidores y la relación entre la utilidad y la recompra es no significativa sólo para los compradores más frecuentes. Algunas ideas para llevar a la práctica son presentadas a modo de discusión

    Socio-economic effects of a HYSOL CSP plant located in different countries: An input output analysis

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    The aim of this paper is to estimate the socioeconomic effects associated with the production of electricity by a CSP plant with HYSOL configuration, using Input Output Analysis. These effects have been estimated in terms of production of Goods and Services (G&S), multiplier effect, value added, contribution to GDP, employment creation and labor intensity. The analysis has been performed considering that the plant was established in four countries contemplated as suitable for HYSOL technology: Spain, Mexico, Chile and Kingdom of Saudi Arabia. The results indicate that producing electricity in a HYSOL CSP plant generates positive impacts on the economy and the employment in every country, producing the following ranges of socio-economic effects: a 0.05%-0.38% increment of the national GDP, creation of 11662-21053 jobs-year and production of 1412-2565 M$ of domestic G&S. The economic results are particularly favorable for Spain and Chile, which has been associated with higher multiplier effects (2.05 and 2.01 respectively) and higher demand of G&S in the Operation and Maintenance phase. In the case of Chile, favorable results are also due to the national production of nitrate salts employed in the thermal energy storage system. Employment results are more favorable in Mexico and Chile, which has been associated with the higher labor intensity of its national economies
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