6,280 research outputs found

    Fractional Newton-Raphson Method Accelerated with Aitken's Method

    Full text link
    The Newton-Raphson (N-R) method is characterized by the fact that generating a divergent sequence can lead to the creation of a fractal, on the other hand the order of the fractional derivatives seems to be closely related to the fractal dimension, based on the above, a method was developed that makes use of the N-R method and the fractional derivative of Riemann-Liouville (R-L) that has been named as the Fractional Newton-Raphson (F N-R) method. In the following work we present a way to obtain the convergence of the F N-R method, which seems to be at least linearly convergent for the case where the order α\alpha of the derivative is different from one, a simplified way to construct the fractional derivative and fractional integral operators of R-L is presented, an introduction to the Aitken's method is made and it is explained why it has the capacity to accelerate the convergence of iterative methods to finally present the results that were obtained when implementing the Aitken's method in F N-R method.Comment: Newton-Raphson Method, Fractional Calculus, Fractional Derivative of Riemann-Liouville, Method of Aitken. arXiv admin note: substantial text overlap with arXiv:1710.0763

    The magnetically-active, low-mass, triple system WDS 19312+3607

    Get PDF
    Aims: We investigated in detail the system WDS 19312+3607, whose primary is an active M4.5Ve star previously thought to be young (tau ~ 300-500 Ma) based on high X-ray luminosity. Methods: We collected intermediate- and low-resolution optical spectra taken with 2 m-class telescopes, photometric data from the BB to 8 mum bands, and eleven astrometric epochs with a time baseline of over 56 years for the two components in the system, G 125-15 and G 125-14. Results: We derived M4.5V spectral types for both stars, confirmed their common proper motion, estimated the heliocentric distance and projected physical separation, determined the galactocentric space velocities, and deduced a most-probable age older than 600 Ma. We discovered that the primary, G 125-15, is in turn an inflated, double-lined, spectroscopic binary with a short period of photometric variability of P ~ 1.6 d, which we associated to orbital synchronisation. The observed X-ray and Halpha emissions, photometric variability, and abnormal radius and effective temperature of G 125-15 AB indicate strong magnetic activity, possibly due to fast rotation. Besides, the estimated projected physical separation between G 125-15 AB and G 125-14 of about 1200 AU makes WDS 19312+3607 to be one of the widest systems with intermediate M-type primaries. Conclusions: G 125-15 AB is a nearby (d ~ 26 pc), bright (J ~ 9.6 mag), active spectroscopic binary with a single proper-motion companion of the same spectral type at a wide separation. They are thus ideal targets for specific follow-ups to investigate wide and close multiplicity or stellar expansion and surface cooling due to reduced convective efficiency.Comment: A&A, in pres

    MicroRNAs Sequencing for Understanding the Genetic Regulation of Plant Genomes

    Get PDF
    MicroRNAs (miRNAs) are endogenous non-coding RNAs that play important regulatory roles in animals and plants by targeting mRNAs for cleavage or translational repression. Small RNAs are classified into different types by their biogenesis and mode of action, such as miRNAs, siRNAs, piRNAs, and snoRNAs. In the case of miRNAs, this specific type regulates gene expression in plants and animals by targeting mRNAs for cleavage and translational repression, respectively. Diverse miRNAs regulate plant development, metabolism, and responses to biotic and abiotic stresses. The identification of miRNAs has been accomplished in diverse species, organs and developmental or diverse biotic and abiotic stress conditions. Novel massive sequencing techniques and further bioinformatics analysis have allowed the identification of hundreds of miRNAs in Arabidopsis thaliana, Oryza sativa, Malus domestica, Zea mays, Solanum lycopersicum, and other plants. Functional characterization of a given miRNA in a specific biological context has shown their role in the fine-tuning mechanisms of posttranscriptional gene regulation. In this chapter, besides making a summary of genome-wide miRNA profiling in plants, we describe how gain and loss of function approaches influence plant phenotypes that affect development, physiology or stress responses, pointing to miRNAs as effective tools for the generation of new plant phenotypes that improve plant productivity and conservation

    The substellar mass function in sigma Orionis. II. Optical, near-infrared and IRAC/Spitzer photometry of young cluster brown dwarfs and planetary-mass objects

    Full text link
    We investigate the mass function in the substellar domain down to a few Jupiter masses in the young sigma Orionis open cluster (3+/-2 Ma, d = 360^+70_-60 pc). We have performed a deep IJ-band search, covering an area of 790 arcmin^2 close to the cluster centre. This survey was complemented with an infrared follow-up in the HKs- and Spitzer 3.6-8.0 mum-bands. Using colour-magnitude diagrams, we have selected 49 candidate cluster members in the magnitude interval 16.1 mag < I < 23.0 mag. Accounting for flux excesses at 8.0 mum and previously known spectral features of youth, 30 objects are bona fide cluster members. Four are first identified from our optical-near infrared data. Eleven have most probable masses below the deuterium burning limit and are classified as planetary-mass object candidates. The slope of the substellar mass spectrum (Delta N / Delta M = a M^-alpha) in the mass interval 0.11 Msol M < 0.006 Msol is alpha = +0.6+/-0.2. Any opacity mass-limit, if these objects form via fragmentation, may lie below 0.006 Msol. The frequency of sigma Orionis brown dwarfs with circumsubstellar discs is 47+/-15 %. The continuity in the mass function and in the frequency of discs suggests that very low-mass stars and substellar objects, even below the deuterium-burning mass limit, may share the same formation mechanism.Comment: Accepted for publication in A&A (12/04/2007). It has not been edited for language ye

    Development and initial validation of a computer-administered health literacy assessment in Spanish and English: FLIGHT/VIDAS.

    Get PDF
    Current measures of health literacy have been criticized on a number of grounds, including use of a limited range of content, development on small and atypical patient groups, and poor psychometric characteristics. In this paper, we report the development and preliminary validation of a new computer-administered and -scored health literacy measure addressing these limitations. Items in the measure reflect a wide range of content related to health promotion and maintenance as well as care for diseases. The development process has focused on creating a measure that will be useful in both Spanish and English, while not requiring substantial time for clinician training and individual administration and scoring. The items incorporate several formats, including questions based on brief videos, which allow for the assessment of listening comprehension and the skills related to obtaining information on the Internet. In this paper, we report the interim analyses detailing the initial development and pilot testing of the items (phase 1 of the project) in groups of Spanish and English speakers. We then describe phase 2, which included a second round of testing of the items, in new groups of Spanish and English speakers, and evaluation of the new measure\u27s reliability and validity in relation to other measures. Data are presented that show that four scales (general health literacy, numeracy, conceptual knowledge, and listening comprehension), developed through a process of item and factor analyses, have significant relations to existing measures of health literacy

    Dietary combination of vitamin E, C and K affects growth, antioxidant activity, and the incidence of systemic granulomatosis in meagre (Argyrosomus regius)

    Get PDF
    Systemic granulomatosis is a growing disease with a high morbidity, which affects to the majority of farmed meagre (Argyrosomus regius). The impossibility of isolating any infectious agents has hypothesized a nutritional origin of the disease. In order to try to elucidate the nutritional origin of granulomas, juvenile meagre were fed for 15 weeks with six diets containing different levels of vitamin E and C and with or without addition of vitamin K: Diet 0 (basal premix, no K, 150 mg kg‐−1 E, 20 mg kg‐−1 C), K (added 23 mg kg‐−1 K), EC (300 mg kg‐−1 E, 70 mg kg‐−1 C), KEC (23 mg kg‐−1 K, 300 mg kg‐−1 E, 70 mg kg‐−1 C), EECC (450 mg kg‐−1 E, 230 mg kg‐−1 C) and KEECC (23 mg kg‐−1 K, 450 mg kg‐−1 E, 230 mg kg‐−1 C). The diet EC significantly increased meagre growth in terms of final weight and length. Fish fed the highest levels of vitamin E and C presented lower percentage of granulomas in liver and heart than fish fed diet 0. The scored severity of granulomatosis in liver and kidney (main affected organs) tended to be lower with dietary increase of vitamin E, C and addition of vitamin K (from 1.83 diet 0 to 1.3 diet KEECC and from 0.91 diet 0 to 0.39 diet KEECC). In liver, the diet KEECC significantly increased catalase expression compared with diet 0. In kidney tnfα expression was significantly up-regulated in fish fed diet EECC and KEECC. In heart, low vitamin E and C levels (300 and 70 mg kg‐−1, respectively) significantly increased superoxide dismutase and glutathione peroxidase expression and high addition increased the expression of tnfα and cox-2 (0 or 23 mg kg‐−1 K, 450 mg kg‐−1 E and 230 mg kg‐−1 C, diet EECC and KEECC). The results show that combination of high dietary content of vitamin K and antioxidant vitamins E and C (23, 450 and 230 mg kg‐−1, respectively) influenced in the incidence of the granulomatosis, which suggests that this pathology could be mediated by nutritional factors

    Implications of zoonotic and vector-borne parasites to free-roaming cats in central Spain

    Get PDF
    Cats are definitive hosts and reservoirs for several parasites, some of which are responsible for serious zoonotic diseases. We conducted a case-control study of data from a trap-neuter-return (TNR) programme (years 2014-2017) designed to examine the prevalence of zoonotic parasites in free-roaming cats living in urban areas of central Spain. In the animal population tested (n = 263), we detected a 29.2% prevalence of endoparasites, including high rates of cestodes (12.9%) and Toxocara cati (11.7%). While faecal samples showed no Toxoplasma gondii oocysts, the seroprevalence of T. gondii infection was 24.2%. Antibodies to Leishmania infantum were detected in 4.8% of the animals, though all skin and blood samples analyzed were PCR negative for this parasite. Ectoparasites (ticks and fleas) were found in 4.6% of the cat population, and 10.6% of the cats were detected with Otodectes cynotis. Finally, 6.3% and 7.9% cats tested positive for feline leukaemia virus and feline immunodeficiency virus, respectively. Our study provides useful information for animal-welfare and public-health, as the parasites detected can affect native wild animals through predation, competition and disease transmission. Our detection of zoonotic parasites such as L. infantum, T. gondii, T. cati, Giardia duodenalis and several ectoparasites prompts an urgent need for health control measures in stray cats.S

    Apoptosis of peritoneal leucocytes during early stages of Fasciola hepatica infections in sheep

    Get PDF
    Several immunomodulatory properties have been described in Fasciola hepatica infections. Apoptosis has been shown to be an effective mechanism to avoid the immune response in helminth infections. The aim of the present work was to study apoptosis in peritoneal leucocytes of sheep experimentally infected with F. hepatica during the early stages of infection. Five groups (n = 5) of sheep were used. Groups 2–5 were orally infected with 200 metacercariae (mc) and sacrificed at 1, 3, 9 and 18 days post-infection (dpi), respectively. Group 1 was used as the uninfected control (UC). Apoptosis was detected using three different methods 1) immunocytochemistry (ICC) with a polyclonal antibody anti-active caspase-3; 2) an annexin V flow cytometry assay using the Annexin V-FITC/propidium iodide (PI); and 3) transmission electron microscopy (TEM). The differential leucocyte count revealed that the majority of peritoneal granulocytes were eosinophils, which increased significantly at 9 and 18 dpi with respect to the uninfected controls. The ICC study revealed that the percentage of caspase-3+ apoptotic peritoneal leucocytes increased significantly from 3 dpi onwards with respect to the uninfected controls. The flow cytometry annexin V assay detected a very significant (P < 0.001) increase of apoptotic peritoneal macrophages, lymphocytes and granulocytes, which remained higher than in the UC until 18 dpi. Transmission electron microscopy studies also confirmed the presence of apoptosis in peritoneal eosinophils at 18 dpi. This is the first report of apoptosis induced by F. hepatica in the peritoneal leucocytes of sheep in vivo. The results of this work suggest the importance of apoptosis induction for the survival of the juvenile parasites in the peritoneal migratory stages of infection.This work was supported by EU grants (H2020-635408-PARAGONE) and the Spanish Ministry of Science grant AGL2015-67023-C2-1-R. The TEM studies were carried out by the Central Research Services (SCAI) of the University of CórdobaAccepted manuscriptVeterinari

    Effect of pH on the production of hydrolytic enzymes of industrial interest by Bacillus licheniformis using sewage sludge as a low-cost culture médium

    Get PDF
    Management of sewage sludge has become a topic of increasing importance. This is because the treatment and final destination of these wastes are not growing at the same rate at which generated what is necessary to add the limited storage capacity of wastewater treatment plants or waste transfer centers. Current policies of different governments aims, among others, promote proecological management of sewage sludge, replacing traditional methods by new methods that lead to their stabilization and safe recycling. These methods can lead to the recovery of valuable raw materials from potentially dangerous others in order to permit their use in agriculture, industry or energy production. Moreover, exists a great enzyme market, mainly those with hydrolytic activities such as proteases, lipases or cellulases. Although its use has many advantages, the competitiveness of the enzymes compared with chemicals is limited by its high production costs. The use of a less expensive culture media and the stimulation of the production of these enzymes can significantly reduce production costs. Therefore, the use of tertiary materials as alternative substrates, available in large quantities and at lower cost, is an interesting option. In this work we have studied the effect of pH on the fermentation of sewage sludge by Bacillus licheniformis, a hydrolytic enzymes producer microorganism, in order to obtain several products for specific agronomic applications
    • 

    corecore