juan ojeda - Academia.edu (original) (raw)

Papers by juan ojeda

Journal of Imaging, 2021

In an early study, the so-called “relevant colour” in a painting was heuristically introduced as ... more In an early study, the so-called “relevant colour” in a painting was heuristically introduced as a term to describe the number of colours that would stand out for an observer when just glancing at a painting. The purpose of this study is to analyse how observers determine the relevant colours by describing observers’ subjective impressions of the most representative colours in paintings and to provide a psychophysical backing for a related computational model we proposed in a previous work. This subjective impression is elicited by an efficient and optimal processing of the most representative colour instances in painting images. Our results suggest an average number of 21 subjective colours. This number is in close agreement with the computational number of relevant colours previously obtained and allows a reliable segmentation of colour images using a small number of colours without introducing any colour categorization. In addition, our results are in good agreement with the dire...

Summary: This article describes the need for the involvement of the health services and regional ... more Summary: This article describes the need for the involvement of the health services and regional headquarters in the development of the dependence law and the strategy developed by the Assertive Community Team (ECA) to reduce the effects of passmark. Also, the position of the Canarian Neuropsychiatry Association (ACN) in the draft decree, with the Government of the Canary Islands, has proposed to establish the Canary System of Dependence Unit (SICAD). Mental health Strategy of the National Health Service (SNS) and the law of the promotion of personal autonomy and care for dependent people, recognize the involvement of health services through interdepartmental coordination mechanisms. The involvement of health services in the field of mental health is more than wrong position to look the other way. Also, if one of the missions of the law is change by creating a stable system of resource of provisions to move from a model of informal’s care

A well known fact perceived in the definition of ordered bases and co- ordinates made in classic ... more A well known fact perceived in the definition of ordered bases and co- ordinates made in classic texts of Linear Algebra is that there is certain ambiguity or imprecision in the formalization of such concepts, as well as the omission of these definitions for infinite dimensional vector spaces. In this article we reformulate the definition of ordered bases and coordinates for vector spaces, in such a way that this definition adjusts perfectly for finite dimensional vector spaces, as well as for infinite dimensional vector spaces. In addition, a precise revision of the theorem of L¨ owig on the invariance of dimensionality is presented.

Journal of Photochemistry and Photobiology, 2021

Abstract The inhibitory effect of Ascorbic Acid (AA) on some pharmaceuticals compounds most comme... more Abstract The inhibitory effect of Ascorbic Acid (AA) on some pharmaceuticals compounds most commercialized in Chile when are exposed to the UV-B radiation was studied. The Nonsteroidal Anti-inflammatory Drugs (NSAIDs) paracetamol, ibuprofen, and ketoprofen, the fluoroquinolones ciprofloxacin and moxifloxacin and the statin atorvastatine were tested using plasma concentrations. The pharmaceutical solutions without and with AA were irradiated with irradiation dose of 216μW cm−2 and its constant and percentage of photodegradation was determined. The results showed that the most of the pharmaceuticals solutions are unstable to UV-B radiation, with the exception of paracetamol, which remained stable after 120 minutes of irradiation. The ketoprofen and ciprofloxacin solutions were the most unstable, reaching a 100 % of photodegradation. The incorporation of AA decreases the percentage and photodegradation constant in all pharmaceuticals solutions. The inhibitory effect on UV-B radiation produced by the AA, can be due to the ability of this vitamin of act as screener or UV light absorbers or react with free radicals and reducing reactive oxygen species, which would cause the structural degradation of drugs.

Reviews of Environmental Contamination and Toxicology, 2020

Journal of Clinical Oncology, 2012

6599 Background: Cytarabine has been set as the main drug included in different schemas for the t... more 6599 Background: Cytarabine has been set as the main drug included in different schemas for the treatment of AML patients. This drug requires inflow to the cell by the nucleoside transporter hENT1 and its activation rate is limited by dCK enzyme. Therefore decreased expression levels of these genes may influence response rate to this drug. Methods: AML patients > 15 years, without previous treatment were included. After informed consent signature, peripheral blood was obtained and DNA was extracted by standard methodology. Amplification of hENT1 and dCK genes was done by RT-PCR. Clinical parameters were registered. All patients received cytarabine + doxorrubicine as induction regimen (7 + 3 schema). Descriptive statistics was used. Uni- and multivariate analysis was done to determine factors influencing on response and overall survival. This protocol was approved by local IRB. Results: From January till December 2011, 22 patients have been included. Median age was 36 years (15-72...

Processes, 2020

The simultaneous adsorption of quinoline and 4,6-dimethyldibenzothiophene over adsorbents, based ... more The simultaneous adsorption of quinoline and 4,6-dimethyldibenzothiophene over adsorbents, based on alumina modified with boron and nickel under ambient temperature and pressure, was studied. The adsorbents were characterized by BET specific surface area, a potentiometric method for the determination of acid strength, electrophoretic migration, and X-ray diffraction. The results showed that the adsorbent containing nickel had better adsorption capacity than the adsorbent modified with nickel and boron, which was attributed to its greater acidity and ability to generate π-complexation between the adsorbent and the molecules. In terms of selectivity, quinoline was more adsorbed than 4,6-dimethyldibenzothiophene in all systems, due to the basic nature of quinoline. The experimental data in all cases were adjusted by three kinetic models (Yoon–Nelson, Yan and Thomas), and the regression coefficients in all models were close to one. Finally, the values of the kinetic constant obtained by...

Microbiology Resource Announcements, 2018

The Quintero Bay, located along the central coast of Chile, has suffered different oil spills dur... more The Quintero Bay, located along the central coast of Chile, has suffered different oil spills during the past 5 years, impacting marine ecosystems. This report describes the microbial community structure of seawater samples obtained from the Quintero Bay through 16S rRNA amplicon sequencing.

Biotechnology Reports, 2018

Biocatalyst systems based on biofilms were developed to remove nitrogen and sulfur-containing het... more Biocatalyst systems based on biofilms were developed to remove nitrogen and sulfur-containing heterocyclic hydrocarbons using Cobetia sp. strain MM1IDA2H-1 and Rhodococcus rhodochrous. The curli overproducers mutants CM 1 and CM 4 were derived from Cobetia sp. strain and used to build monostrain biofilms to remove quinoline; and together with R. rhodochrous to simultaneously remove quinoline and dibenzothiophene using mixed biofilms. The quinoline removal using biofilms were 96% and 97% using CM 1 or CM 4 curli overproducers respectively, whereas bacterial suspensions assays yielded 19% and 24% with the same strains. At the other hand, the simultaneous removal of quinoline and dibenzothiophene using mixed biofilms were respectively 50% and 58% using strains R. rhodochrous with CM 1 and 75% and 50% using R. rhodochrous with CM 4. Results show that biofilms were more efficient than bacterial suspension assays and that in mixed biofilms the shared surface area by two or more bacteria could affect the final yield.

Applied Optics, 2017

Despite the global and local daylight changes naturally occurring in natural scenes, the human vi... more Despite the global and local daylight changes naturally occurring in natural scenes, the human visual system usually adapts quite well to those changes, developing a stable color perception. Nevertheless, the influence of daylight in modeling natural image statistics is not fully understood and has received little attention. The aim of this work was to analyze the influence of daylight changes in different high-order chromatic descriptors (i.e., color volume, color gamut, and number of discernible colors) derived from 350 color images, which were rendered under 108 natural illuminants with Correlated Color Temperatures (CCT) from 2735 to 25,889 K. Results suggest that chromatic and luminance information is almost constant and does not depend on the CCT of the illuminant for values above 14,000 K. Nevertheless, differences between the red-green and blue-yellow image components were found below that CCT, with most of the statistical descriptors analyzed showing local extremes in the range 2950 K-6300 K. Uniform regions and areas of the images attracting observers' attention were also considered in this analysis and were characterized by their patchiness index and their saliency maps. Meanwhile, the results of the patchiness index do not show a clear dependence on CCT, and it is remarkable that a significant reduction in the number of discernible colors (58% on average) was found when the images were masked with their corresponding saliency maps. Our results suggest that chromatic diversity, as defined in terms of the discernible colors, can be strongly reduced when an observer scans a natural scene. These findings support the idea that a reduction in the number of discernible colors will guide visual saliency and attention. Whatever the modeling is mediating the neural representation of natural images, natural image statistics, it is clear that natural image statistics should take into account those local maxima and minima depending on the daylight illumination and the reduction of the number of discernible colors when salient regions are considered.

Revista de investigacion clinica; organo del Hospital de Enfermedades de la Nutricion

Hyper-CVAD is the treatment for patients with acute lymphoblastic leukemia in our institution. To... more Hyper-CVAD is the treatment for patients with acute lymphoblastic leukemia in our institution. To evaluate the impact of single nucleotide polymorphisms at genes associated with methotrexate metabolism on survival. The presence of the single nucleotide polymorphisms G80A at reduced folate carrier-1 gene and C677T in the methylenetetrahydrofolate reductase gene was determined by denaturing high performance liquid chromatography and validated by sequencing. Both single nucleotide polymorphisms were evaluated in 71 healthy donors and in an exploratory pilot trial with acute lymphoblastic leukemia patients to determine the influence of these single nucleotide polymorphisms on clinical outcome. Clinical characteristics, response, and outcome were registered. A Cox regression analysis was done to evaluate factors influencing response and overall survival. There were no differences in the frequency of single nucleotide polymorphisms between volunteers and acute lymphoblastic leukemia patie...

Mundo Electronico, 2008

Desde las primeras transmisiones inalambricas, las interferencias electromagneticas (EMI) han sid... more Desde las primeras transmisiones inalambricas, las interferencias electromagneticas (EMI) han sido una preocupacion para los ingenieros de diseno. Los organismos reguladores han puesto limites a los niveles de EMI y han definido los metodos de medida para las pruebas de conformidad. Estos metodos han estado en vigor durante decadas y fueron escritos para dar cabida a las necesidades de las transmisiones analogicas de voz y video y constituian el metodo de prueba disponible en el momento de su escritura.

Opcion Revista De Ciencias Humanas Y Sociales, 2012

El presente artículo tiene como objetivo analizar el valor ético de la responsabilidad social en ... more El presente artículo tiene como objetivo analizar el valor ético de la responsabilidad social en la investigación, entendiendo que los resultados de la misma deben dar un aporte de solución a los problemas sociales. El estudio es de tipo documental. Entre sus resultados se destaca el hecho, en la cual, el significado del valor ético de la responsabilidad social en la comunidad científica, debe asumirse como el compromiso u obligación que tienen los investigadores, de generar beneficios para la sociedad. El concepto introduce una valoración, positiva o negativa, al impacto que tiene ante la sociedad las decisiones científicas.

Revista Espanola De Electronica, 2008

Estudios De Historia De Espana, 2005

La inclusion de Alava en el ambito castellano produce una progresiva modificacion de la situacion... more La inclusion de Alava en el ambito castellano produce una progresiva modificacion de la situacion politica, social y economica de la region. El senorio de Ayala sufre una paulatina intromision del realengo en su jurisdiccion, lo que debilita la autoridad de su senor sobre los organismos tradicionales de gobierno. La crisis interna del senorio deriva en un conflicto sucesorio aprovechado por Castilla para intensificar su control sobre la Tierra de Ayala.

Revista De Filosofia, 2002

El Ciervo Revista Mensual De Pensamiento Y Cultura, 1986

El Ciervo Revista Mensual De Pensamiento Y Cultura, 2001