129 research outputs found

    The structure and evolution of confined tori near a Hamiltonian Hopf Bifurcation

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    We study the orbital behavior at the neighborhood of complex unstable periodic orbits in a 3D autonomous Hamiltonian system of galactic type. At a transition of a family of periodic orbits from stability to complex instability (also known as Hamiltonian Hopf Bifurcation) the four eigenvalues of the stable periodic orbits move out of the unit circle. Then the periodic orbits become complex unstable. In this paper we first integrate initial conditions close to the ones of a complex unstable periodic orbit, which is close to the transition point. Then, we plot the consequents of the corresponding orbit in a 4D surface of section. To visualize this surface of section we use the method of color and rotation [Patsis and Zachilas 1994]. We find that the consequents are contained in 2D "confined tori". Then, we investigate the structure of the phase space in the neighborhood of complex unstable periodic orbits, which are further away from the transition point. In these cases we observe clouds of points in the 4D surfaces of section. The transition between the two types of orbital behavior is abrupt.Comment: 10 pages, 14 figures, accepted for publication in the International Journal of Bifurcation and Chao

    Infiltrative lipoma on the forearm of a horse

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    This case report describes an infiltrative lipoma in a horse. A slow-growing mass, detected early after birth, was present at the caudal aspect of the foreleg (antebrachium) of a 2-year-old gelding. Cytological features were that of a benign lipoma. Surgical resection was attempted but failed due to the infiltrative nature of the mass. Consequently, the horse was euthanized. Histopathology revealed an infiltrative lipoma. This tumor is histologically benign but surgical resection is usually impossible due to its infiltrative nature

    LACK OF GENETIC DIFFERENTIATION IN THE ALTANTIC DISTRIBUTION OF WAHOO

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    SUMMARY In this study we present the analysis of the stock structure of Wahoo (Acanthocybium solandri) using the mitochondrial control region as genetic marker. We analyzed 276 individuals distributed in four locations int eh east and west Atlantic. Samples were from: Northeast Atlantic (AT-NE/BIL94B) (Canary Islands, Spain), from Southeast Atlantic (AT-SE/BIL97) (Côte d’Ivoire and Gabon) and Southwest Atlantic (AT-SW/BIL96). Four of individuals from Southwest Atlantic (AT-SW/BIL96) were genetically identified as Scomberomorus cavalla. The genetic comparison of the four locations failed to show genetic differences. This result suggests a single genetic pool of the Wahoo in the whole Atlantic. Based on these results, ICCAT should reconsider their management strategies for this species in the area studied. RÉSUMÉ Dans cette étude, nous présentons l’analyse de la structure du stock de thazard-bâtard (Acanthocybium solandri) en utilisant la région de contrôle de l’ADN mitochondrial comme marqueur génétique. Nous avons analysé 276 spécimens répartis dans quatre zones de l’Atlantique Est et Ouest. Les échantillons provenaient de : l’Atlantique Nord-Est (AT-NE/BIL94B) (îles Canaries, Espagne), l’Atlantique Sud-Est (AT-SE/BIL97) (Côte d’Ivoire et Gabon) et l’Atlantique Sud-Ouest (AT-SW/BIL96). Quatre spécimens provenant de l’Atlantique Sud-Ouest (AT-SW/BIL96) ont été génétiquement identifiés comme Scomberomorus cavalla. La comparaison génétique des quatre zones n’a pas révélé de différences génétiques. Ce résultat donne à penser à un patrimoine génétique du thazard-bâtard dans l’ensemble de l’Atlantique. En se fondant sur ces résultats, l’ICCAT devrait revoir ses stratégies de gestion pour cette espèce dans la zone à l’étude. RESUMEN En este estudio presentamos el análisis de la estructura del stock del peto (Acanthocybium solandri) utilizando la región de control mitocondrial como marcador genético. Hemos analizado 276 ejemplares distribuidos en cuatro localizaciones en el Atlántico este y oeste. Las muestras procedían de: Atlántico nororiental (AT-NE/BIL94B) (islas Canarias, España), del Atlántico suroriental (AT-SE/BIL97) (Côte d'Ivoire y Gabón) y del Atlántico sudoccidental (AT-SW/BIL96). Cuatro de los ejemplares del Atlántico sudoccidental (AT-SW/BIL96) fueron genéticamente identificados como Scomberomorus cavalla. La comparación genética de las cuatro localizaciones no mostraba diferencias genéticas. Este resultado sugiere un único acervo genético del peto en todo el Atlántico. Basándose en estos resultados, ICCAT debería reconsiderar la estrategia de ordenación para esta especie en la zona estudiada.Versión del edito

    Galactic kinematics with modified Newtonian dynamics

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    We look for observational signatures that could discriminate between Newtonian and modified Newtonian (MOND) dynamics in the Milky Way, in view of the advent of large astrometric and spectroscopic surveys. Indeed, a typical signature of MOND is an apparent disk of "phantom" dark matter, which is uniquely correlated with the visible disk-density distribution. Due to this phantom dark disk, Newtonian models with a spherical halo have different signatures from MOND models close to the Galactic plane. The models can thus be differentiated by measuring dynamically (within Newtonian dynamics) the disk surface density at the solar radius, the radial mass gradient within the disk, or the velocity ellipsoid tilt angle above the Galactic plane. Using the most realistic possible baryonic mass model for the Milky Way, we predict that, if MOND applies, the local surface density measured by a Newtonist will be approximately 78 Msun/pc2 within 1.1 kpc of the Galactic plane, the dynamically measured disk scale-length will be enhanced by a factor of 1.25 with respect to the visible disk scale-length, and the local vertical tilt of the velocity ellipsoid at 1 kpc above the plane will be approximately 6 degrees. None of these tests can be conclusive for the present-day accuracy of Milky Way data, but they will be of prime interest with the advent of large surveys such as GAIA.Comment: 5 page

    Results of salt intake restriction monitored with the new sodium control biosensor

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    Adherence to a low sodium (Na) diet is crucial in patients under hemodialysis, as it improves cardiovascular outcomes and reduces thirst and interdialytic weight gain. Recommended salt intake is lower than 5 g/day. The new 6008 CareSystem monitors incorporate a Na module that offers the advantage of estimating patients' salt intake. The objective of this study was to evaluate the effect of dietary Na restriction for 1 week, monitored with the Na biosensor.A prospective study was conducted in 48 patients who maintained their usual dialysis parameters and were dialyzed with a 6008 CareSystem monitor with activation of the Na module. Total Na balance, pre/postdialysis weight, serum Na (sNa), changes in pre- to post-dialysis sNa (ΔsNa), diffusive balance, and systolic and diastolic blood pressure were compared twice, once after 1 week of patients' usual Na diet and again after another week with more restricted Na intake.Restricted Na intake increased the percentage of patients on a low-sodium diet (<85 Na mmol/day) from 8% to 44%. Average daily Na intake decreased from 149 ± 54 to 95 ± 49 mmol and interdialytic weight gain was reduced by 460 ± 484 g per session. More restricted Na intake also decreased pre-dialysis sNa and increased both intradialytic diffusive balance and ΔsNa. In hypertensive patients, reducing daily sodium by more than 3 g Na/day lowered their systolic blood pressure.The new Na module allowed objective monitoring of Na intake, which in turn could permit more precise personalized dietary recommendations in patients under hemodialysis.S. Karger AG, Basel

    Investigation on the structural changes of ZnO:Er:Yb thin film during laser annealing to fabricate a transparent conducting upconverter

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    A transparent and conducting ZnO:Er:Yb thin film with upconversion properties has been achieved after being annealed with continuous laser radiation just before the ablation point of the material. This work demonstrates that the laser energy preserves the conductivity of the film and at the same time creates an adequate surrounding for Er and Yb to produce visible upconversion at 660, 560, 520, and 480 nm under 980 nm laser excitation. The relation between the structural, electrical and upconversion properties is discussed. It is observed that the laser energy melts part of the material, which recrystallizes creating rare earth oxides and two different wurtzite structures, one with substitutional rare earths and oxygen vacancies (responsible for the conductivity) and the other without substitutional rare earth ions (responsible for the upconversion emission)

    Final report of the short-term contract for ICCAT SMYTP for the biological samples collection for growth, maturity and genetics studies – Year #2

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    This document is the final report of the second year of the short-term contract of the Small Tuna Year Program by ICCAT. In 2018, the Small Tuna Species Group decided to prioritize Little tunny (LTA) (Euthynnus alletteratus) Atlantic bonito (BON) (Sarda sarda) and Wahoo (WAH) (Acanthocybium solandri), based on their economic importance and the deficiency of knowledge of their biology. The objectives of the contract for three species were: i) Collect biological samples for estimating growth parameters, assessing the maturity and stock structure analysis (populations genetics), and ii) Conclude the analysis of the stock structure for at least one of the three species and provide preliminary results for the remaining. The obtained samples for growth, maturity and stock structure analysis was almost completed for Little tunny and Atlantic bonito, whereas for Wahoo the samples are scarce. The analysis of stock structure for Little tunny and Atlantic bonito revealed that the observed dif

    Microbotanical residues for the study of early hominin tools

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    More than 2 million years ago in East Africa, the earliest hominin stone tools evolved amidst changes in resource base, with pounding technology playing a key role in this adaptive process. Olduvai Gorge (now Oldupai) is a famed locality that remains paramount for the study of human evolution, also yielding some of the oldest battering tools in the world. However, direct evidence of the resources processed with these technologies is lacking entirely. One way to obtain this evidence is through the analysis of surviving residues. Yet, linking residues with past processing activities is not simple. In the case of plant exploitation, this link can only be established by assessing site-based reference collections inclusive of both anthropogenic and natural residues as a necessary first step and comparative starting point. In this paper, we assess microbotanical remains from rock clasts sourced at the same quarry utilized by Oldowan hominins at Oldupai Gorge. We mapped this signal and analysed it quantitatively to classify its spatial distribution objectively, extracting proxies for taxonomic identification and further comparison with freestanding soils. In addition, we used blanks to manufacture pounding tools for blind, controlled replication of plant processing. We discovered that stone blanks are in fact environmental reservoirs in which plant remains are trapped by lithobionts, preserved as hardened accretions. Tool use, on the other hand, creates residue clusters; however, their spatial distribution can be discriminated from purely natural assemblages by the georeferencing of residues and statistical analysis of resulting patterns. To conclude, we provide a protocol for best practice and a workflow that has the advantage of overcoming environmental noise, reducing the risk of false positive, delivering a firm understanding of residues as polygenic mixtures, a reliable use of controls, and most importantly, a stronger link between microbotanical remains and stone tool use. © 2022. The Author(s).Materials and methods Results - Blanks as environmental reservoirs - Utilization creates residue clusters - Anthropogenic residue distribution - Of lichen habitability, proxy palimpsests, and hardened accretions - A protocol to study plant residue from Oldowan pounding tool

    Evaluation of antimicrobial effectiveness of pimaricin-loaded thermosensitive nanohydrogels in grape juice

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    Pimaricin-loaded poly(N-isopropylacrylamide) nanohydrogels with and without acrylic acid, were evaluated as food-spoilage inhibitors in a model system and a real food product: grape juice. Pimaricin was proposed as a non-allergenic alternative to sulphites for protecting juices against recontamination. However, pimaricin may degrade under conditions and treatments (heating, acidification, lighting) commonly applied in producing fresh juices. Nanohydrogel encapsulation may be a feasible procedure to avoid pimaricin degradation, improving its antimicrobial activity. Pimaricin-free nanohydrogels did not affect the growth of the indicator yeast either in the food model system or in grape juice. Conversely, pimaricin-loaded nanohydrogels effectively inhibited the growth of the indicator yeast. In some cases, the inhibition was extended even further than using free pimaricin. For instance, in the food model system, pimaricin-loaded nanohydrogels with acrylic acid (NPPNIPA-20AA(5)) prevented the yeast growth for more than 81 h while free pimaricin was only effective for 12 h. Despite pimaricin-loaded nanohydrogels without acrylic acid (NPPNIPA(5)) were able to reduce maximum yeast growth, as in all treatments with pimaricin, the extent of the inhibitory effect was not significantly (p>0.05) different to that achieved with free pimaricin. In grape juice, both free pimaricin and NPPNIPA-20AA(5) treatment completely inhibited the growth of the indicator yeast until the end of the bioassay. However, the latter provided similar inhibition levels using a smaller amount of pimaricin due to PNIPA-20AA(5) protection and its controlled release from the nanohydrogel. Therefore, nanohydrogel encapsulation may help to optimise antifungal treatments and decrease the incidence of food allergies.Funded by grant (MAT 2006-11662-CO3-CO2-C01/MAT 2010-21509-C03-01/EUI 2008-00115) from the “Ministerio de Educación y Ciencia” (Spain). Grant (SFRH/BPD/87910/2012) from the Fundação para a Ciência e Tecnologia (FCT, Portugal). Marie Curie COFUND Postdoctoral Research Fellow
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