On a generalization of the Pell sequence

The Pell sequence $(P_n)_{n=0}^{\infty}$ is the second order linear recurrence defined by $P_n=2P_{n-1}+P_{n-2}$ with initial conditions $P_0=0$ and $P_1=1$. In this paper, we investigate a generalization of the Pell sequence called the $k$-generalized Pell sequence which is generated by a recurrence relation of a higher order. We present recurrence relations, the generalized Binet formula and different arithmetic properties for the above family of sequences. Some interesting identities involving the Fibonacci and generalized Pell numbers are also deduced

Fermat kk-Fibonacci and kk-Lucas numbers

summary:Using the lower bound of linear forms in logarithms of Matveev and the theory of continued fractions by means of a variation of a result of Dujella and Pethő, we find all $k$-Fibonacci and $k$-Lucas numbers which are Fermat numbers. Some more general results are given

Paisajes y flora forestal de al-Andalus: una reconstrucción a partir de documentación histórica textual

The translation and interpretation of works by Andalusi botanists and agronomists provide an increasingly sharp image of the species and forest landscapes in al-Andalus (Iberian area under Muslim rule in the Middle Ages). Regarding agriculture, it is known that domestication processes and the introduction of new species and singular forms of use were carried out, thus changing agricultural landscapes. Consequently, new life styles and consumption habits developed. A lot less is known about forestry management, especially when referring to forest landscapes and tree species in the Iberian Peninsula. The authors of this work have been studying agricultural and forest flora in al-Andalus for many years. In addition to numerous miscellaneous contributions, their first approximation on the trees and shrubs cultivated there was published in 2004, and the first volume of Flora Agrícola y Forestal de Al-Andalus covering 80 species of monocotyledons appeared in 2012. In anticipation of the volume devoted to woody dicotyledons to be published in 2019 (including over 150 species, 100 genera and 50 families), a synthesis of the forest landscapes and the most unique species in the Arabic texts is presented in this work. Among the taxa identified are Iberian endemics such as Flueggea tinctoria and Corema album, rare taxa or highly localized ones like Rhododendron ponticum subsp. baeticum, Tetraclinis articulata and Zizyphus lotus with species of peculiar forestry interest such as Arctostaphylos uva-ursi, Taxus baccata, Buxus sempervirens, Ilex aquifolium, Laurus nobilis and Vitex agnus-castus, and archaeophytes like Celtis australis or Anagyris foetida.La traducción e interpretación de las obras de botánicos y geóponos andalusíes permite vislumbrar, de forma cada vez más nítida, las especies y paisajes forestales de al-Andalus (área ibérica bajo dominación musulmana en la Edad Media). En el ámbito agrícola es conocido que se desarrollaron procesos de domesticación e introducción de nuevas especies y formas singulares de uso que cambiaron los paisajes agrícolas y, en consecuencia, también las formas de vida y alimentación, pero es mucho menos conocido lo concerniente al ámbito forestal, especialmente si nos referimos a los paisajes y especies forestales ibéricas. Los autores estudian la Flora Agrícola y Forestal en al-Andalus. Además de numerosas contribuciones misceláneas, una primera aproximación sobre los árboles y arbustos cultivados fue publicada en 2004, y un primer volumen de la citada Flora en 2012, abarcando 80 especies de monocotiledóneas. Como adelanto al volumen dedicado a las dicotiledóneas leñosas, que será publicado en 2019 (con más de 150 especies de 100 géneros y 50 familias), se presenta ahora una síntesis de los paisajes forestales y de las especies más singulares identificadas en los textos estudiados. Entre ellas hay endemismos ibéricos como Fluggea tinctoria y Corema album, taxones raros o muy localizados como Rhododendron ponticum subsp. baeticum, Tetraclinis articulata o Zizyphus lotus, junto a especies de singular interés forestal como Arctostaphilos uva-ursi, Taxus baccata, Buxus sempervirens, Ilex aquifolium, Laurus nobilis o Vitex agnus-castus, y arqueófitos como Celtis australis o Anagyris foetida

Vimentin and heat shock protein expression are induced in the kidney by angiotensin and by nitric oxide inhibition

Vimentin and heat shock protein expression are induced in the kidney by angiotensin and by nitric oxide inhibition.BackgroundAngiotensin II (Ang II) infusion and nitric oxide synthesis (NOS) inhibition with Nω-nitro-L-arginine-methyl-ester (L-NAME) are experimental models of hypertension associated with renal inflammation and oxidative stress. To gain insight into the nature of the tubulointerstitial injury induced in these models, we studied lectin-binding specificities, vimentin expression, and heat shock protein (HSP) 60 and 70 in these experimental models.MethodsSprague-Dawley rats received Ang II infusion (435 ng/kg/min) for 2 weeks by subcutaneous minipumps (Ang II group, N = 5) or L-NAME in the drinking water (70 mg/100 mL) for 3 weeks (L-NAME group N = 7). The control group consisted of 10 rats. Systolic blood pressure (tail-cuff plethysmography), serum creatinine, and proteinuria were determined weekly. At the end of the treatment period, rats were sacrificed and kidneys studied. Binding specificities of fluorescein-labeled lectins were examined in frozen sections, and cellular infiltrates were identified by immunohistology and expression of vimentin and HSP 60 and 70 with immunohistochemistry and computer image analysis.ResultsTubulointerstitial accumulation of macrophages, lymphocytes, and Ang II–positive cells were present in the Ang II group and L-NAME group. Vimentin, HSP 60, and HSP 70 were increased 8 to 20 times in the cortex of the rats of the Ang II group and the L-NAME groups. Neoexpression of vimentin and HSPs was found primarily in proximal tubular cells.ConclusionAng II infusion and NOS inhibition induce tubular injury with epithelial cell transdifferentiation and expression of stress proteins. The role of these changes in the accumulation and activation of the interstitial inflammatory infiltrate merits further investigation

The lava delta of Igueste de San Andrés (Anaga, Tenerife, Canary Islands)

Los restos de un delta de lava afloran dentro de la Serie I Media del Macizo de Anaga, en la parte nororiental de la isla de Tenerife (Islas Canarias), en el tramo bajo del Barranco de Igueste de San Andrés, a unos 90 metros de altura. El delta está formado principalmente por flujos de lavas basálticas de baja viscosidad que cubren lavas almohadilladas, brechas de fragmentos de almohadillas, más o menos resedimentadas, e hialoclastitas, ordenadas en foresets con buzamientos altos hacia el sur. Cubren erosivamente el delta aglomerados constituidos por fragmentos procedentes de las diferentes facies del delta y niveles de lavas y piroclásticos subaéreos, formados por pequeñas erupciones estrombolianas costerasThe remains of a lava delta occur within the volcanic succession called Serie I Media in the Anaga Massif, in the northeastern part of Tenerife Island (Canary Islands). The outcrop is located in the lower part of the ravine of Igueste de San Andrés, at about 90 meters high. The delta is formed mainly of flows of low viscosity basaltic lavas that cover pillowlavas, roughly resedimented pillow-fragment breccias, and hyaloclastites, in foreset bodies with high dips towards the S. The delta is covered by agglomerates constituted by fragments from the different facies of the delta and levels of lavas and subaerial pyroclasts, formed of small coastal strombolian eruption

Effects of transcranial static magnetic field stimulation over the left dorsolateral prefrontal cortex on random number generation

OBJECTIVE: Focal application of transcranial static magnetic field stimulation (tSMS) is a neuromodulation technique, with predominantly inhibitory effects when applied to the motor, somatosensory or visual cortex. Whether this approach can also transiently interact with dorsolateral prefrontal cortex (DLPFC) function remains unclear. The suppression of habitual or competitive responses is one of the core executive functions linked to DLPFC function. This study aimed to assess the impact of tSMS on the prefrontal contributions to inhibitory control and response selection by means of a RNG task. METHODS: We applied 20 min of tSMS over the left DLPFC of healthy subjects, using a real/sham cross-over design, during performance of a RNG task. We used an index of randomness calculated with the measures of entropy and correlation to assess the impact of stimulation on DLPFC function. RESULTS: The randomness index of the sequences generated during the tSMS intervention was significantly higher compared to those produced in the sham condition. CONCLUSIONS: Our results indicate that application of tSMS transiently modulates specific functional brain networks in DLPFC, which indicate a potential use of tSMS for treatment of neuropsychiatric disorders. SIGNIFICANCE: This study provides evidence for the capacity of tSMS for modulating DLPFC function

Production, Transmission, Pathogenesis, and Control of Dengue Virus: A Literature-Based Undivided Perspective

Dengue remains one of the most serious and widespread mosquito-borne viral infections in human beings, with serious health problems or even death. About 50 to 100 million people are newly infected annually, with almost 2.5 billion people living at risk and resulting in 20,000 deaths. Dengue virus infection is especially transmitted through bites of Aedes mosquitos, hugely spread in tropical and subtropical environments, mostly found in urban and semiurban areas. Unfortunately, there is no particular therapeutic approach, but prevention, adequate consciousness, detection at earlier stage of viral infection, and appropriate medical care can lower the fatality rates. This review offers a comprehensive view of production, transmission, pathogenesis, and control measures of the dengue virus and its vectors.This work was supported by CONICYT PIA/APOYO CCTE AFB170007

Cyperus spp.: A Review on Phytochemical Composition, Biological Activity, and Health-Promoting Effects

Cyperaceae are a plant family of grass-like monocots, comprising 5600 species with a cosmopolitan distribution in temperate and tropical regions. Phytochemically, Cyperus is one of the most promising health supplementing genera of the Cyperaceae family, housing ˜950 species, with Cyperus rotundus L. being the most reported species in pharmacological studies. The traditional uses of Cyperus spp. have been reported against various diseases, viz., gastrointestinal and respiratory affections, blood disorders, menstrual irregularities, and inflammatory diseases. Cyperus spp. are known to contain a plethora of bioactive compounds such as a-cyperone, a-corymbolol, a-pinene, caryophyllene oxide, cyperotundone, germacrene D, mustakone, and zierone, which impart pharmacological properties to its extract. Therefore, Cyperus sp. extracts were preclinically studied and reported to possess antioxidant, anti-inflammatory, antimicrobial, anticancer, neuroprotective, antidepressive, antiarthritic, antiobesity, vasodilator, spasmolytic, bronchodilator, and estrogenic biofunctionalities. Nonetheless, conclusive evidence is still sparse regarding its clinical applications on human diseases. Further studies focused on toxicity data and risk assessment are needed to elucidate its safe and effective application. Moreover, detailed structure-activity studies also need time to explore the candidature of Cyperus-derived phytochemicals as upcoming drugs in pharmaceuticals.NM acknowledges the Portuguese Foundation for Science and Technology under the Horizon 2020 Program (PTDC/PSI-GER/28076/2017)

Lasia spinosa Chemical Composition and Therapeutic Potential: A Literature-Based Review

Lasia spinosa (L.) is used ethnobotanically for the treatment of various diseases, including rheumatoid arthritis, inflammation of the lungs, bleeding cough, hemorrhoids, intestinal diseases, stomach pain, and uterine cancer. This review is aimed at summarizing phytochemistry and pharmacological data with their molecular mechanisms of action. A search was performed in databases such as PubMed, Science Direct, and Google Scholar using the keywords: "Lasia spinosa,"then combined with "ethnopharmacological use,""phytochemistry,"and "pharmacological activity."This updated review included studies with in vitro, ex vivo, and in vivo experiments with compounds of known concentration and highlighted pharmacological mechanisms. The research results showed that L. spinosa contains many important nutritional and phytochemical components such as alkanes, aldehydes, alkaloids, carotenoids, flavonoids, fatty acids, ketones, lignans, phenolics, terpenoids, steroids, and volatile oil with excellent bioactivity. The importance of this review lies in the fact that scientific pharmacological evidence supports the fact that the plant has antioxidant, anti-inflammatory, antimicrobial, cytotoxic, antidiarrheal, antihelminthic, antidiabetic, antihyperlipidemic, and antinociceptive effects, while protecting the gastrointestinal system and reproductive. Regarding future toxicological and safety data, more research is needed, including studies on human subjects. In light of these data, L. spinosa can be considered a medicinal plant with effective bioactives for the adjuvant treatment of various diseases in humans.This work was supported by Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) PIA/APOYO CCTE AFB170007. N.C.-M. acknowledges the Portuguese Foundation for Science and Technology under the Horizon 2020 Program (PTDC/PSI-GER/28076/2017)