165 research outputs found

    Noncollinear exchange interaction in transition metal dichalcogenide edges

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    We study the Ruderman-Kittel-Kasuya-Yosida effective exchange interaction between magnetic impurities embedded on the edges of transition-metal dichalcogenide flakes, using a three-orbital tight-binding model. Electronic states lying midgap of the bulk structure have strong one-dimensional (1D) character, localized on the edges of the crystallite. This results in exchange interactions with 1/r1/r (or slower) decay with distance rr, similar to other 1D systems. Most interestingly, however, the strong spin-orbit interaction in these materials results in sizable non-collinear Dzyaloshinskii-Moriya interactions between impurities, comparable in size to the usual Ising and in-plane components. Varying the relevant Fermi energy by doping or gating may allow one to modulate the effective interactions, controlling the possible helical ground state configurations of multiple impurities.Comment: 5 pages and 4 figure

    Lateral Interfaces of Transition Metal Dichalcogenides: A Stable Tunable One-Dimensional Physics Platform

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    We study in-plane lateral heterostructures of commensurate transition-metal dichalcogenides, such as MoS2_{2}-WS2_{2} and MoSe2_{2}-WSe2_{2}, and find interfacial and edge states that are highly localized to these regions of the heterostructure. These are one-dimensional (1D) in nature, lying within the bandgap of the bulk structure and exhibiting complex orbital and spin structure. We describe such heteroribbons with a three-orbital tight-binding model that uses first principles and experimental parameters as input, allowing us to model realistic systems. Analytical modeling for the 1D interfacial bands results in long-range hoppings due to the hybridization along the interface, with strong spin-orbit couplings. We further explore the Ruderman-Kittel-Kasuya-Yosida indirect interaction between magnetic impurities located at the interface. The unusual features of the interface states result in effective long-range exchange non-collinear interactions between impurities. These results suggest that transition-metal dichalcogenide interfaces could serve as stable, tunable 1D platform with unique properties for possible use in exploring Majorana fermions, plasma excitations and spintronics applications.Comment: 12 pages, 7 figure

    A time-domain fourth-order-convergent numerical algorithm to integrate black hole perturbations in the extreme-mass-ratio limit

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    We obtain a fourth order accurate numerical algorithm to integrate the Zerilli and Regge-Wheeler wave equations, describing perturbations of nonrotating black holes, with source terms due to an orbiting particle. Those source terms contain the Dirac's delta and its first derivative. We also re-derive the source of the Zerilli and Regge-Wheeler equations for more convenient definitions of the waveforms, that allow direct metric reconstruction (in the Regge-Wheeler gauge).Comment: 30 pages, 12 figure

    Effect of Greenhouse Film Cover on the Development of Fungal Diseases on Tomato (Solanum lycopersicum L.) and Pepper (Capsicum annuum L.) in a Mediterranean Protected Crop

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    Greenhouses on the Mediterranean coast mainly use plastic materials as their cover. The influence of light exerted by these materials directly affects the crops by modifying the environment in which they develop. The aim of this study was to analyze the effect of the use of two plastic films in an experimental greenhouse on the development of fungal diseases in two spring–summer crop cycles: tomato (Solanum lycopersicum L.) from february to July 2021 and pepper (Capsicum annuum L.) from February to July 2022. The study was carried out in Almeria (Spain) in a multispan greenhouse divided transversely into two sectors by a polyethylene sheet. A commercial film was installed in the east sector (90% of transmissivity and 55% diffusivity) and an experimental film was installed in the west sector (85% of transmissivity and 60% diffusivity). In addition, the effect of the yield and quality of the harvested fruit was determined. In this study, two diseases were established naturally on the crop: (i) powdery mildew (Leveillula taurica) in both the tomato and the pepper crop cycles and (ii) early blight (Alternaria solani) in the tomato. The analyses of both diseases showed that the areas of the greenhouse that used the plastic cover, which presented a lower sunlight transmissivity, showed higher levels of disease than the areas that used the plastic cover that allowed greater transmissivity of light within the greenhouse, differing statistically in some phases of the crop. The marketable yield was 4.2% (for tomato) and 3.1% (for pepper) higher in the sector with the experimental film with high transmissivity. For both crops, the quality of the fruits did not show statistically significant difference

    Finger Temperature: A Psychophysiological Assessment of the Attentional State

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    Attention is a key cognitive phenomenon that is studied to understand cognitive disorders or even to estimate workloads to prevent accidents. Usually, it is studied using brain activity, even though it has many psychophysiological correlates. In the present study, we aim to evaluate if finger temperature, as a surrogate of peripheral vasoconstriction, can be used to obtain similar and complementary information to electroencephalography (EEG) brain activity measurements. To conduct this, 34 participants were recruited and submitted to performing four tasks—one as a baseline, and three attentional tasks. These three attentional tasks measured sustained attention, resilience to distractors, and attentional resources. During the tasks, the room, forehead, tympanic, and finger temperatures were measured. Furthermore, we included a 32-channel EEG recording. Our results showed a strong monotonic association between the finger temperature and the Alpha and Beta EEG spectral bands. When predicting attentional performance, the finger temperature was complementary to the EEG spectral measurements, through the prediction of aspects of attentional performance that had not been assessed by spectral EEG activity, or through the improvement of the model’s fit. We also found that during the baseline task (non-goal-oriented task), the spectral EEG activity has an inverted correlation, as compared to a goal-oriented task. Our current results suggest that the psychophysiological assessment of attention is complementary to classic EEG approach, while also having the advantage of easy implementation of analysis tools in environments of reducing control (workplaces, student classrooms)

    Removal Of Reactive Black 5 From Textile Wastewater By Ozone And Photo-Fenton: Influence Of Indusrial Matrix Effects

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    Textile waste water containing dyes, surfactants, salts and other contaminants represent a challenge for the selection and design of treatment processes due to the stability of some of its compo-nents. Advanced oxidation processes (AOPs) are at-tractive alternatives to partially or totally degrade dyes and other persistent pollutants using relatively compact devices to perform water treatment. To test the efficiency of these technologies it is necessary to count with laboratory made solutions that can match the characteristics of a typical textile waste waters ef-fluent. In this work the application of two AOP, ozo-nation and photo-Fenton, to the treatment of textile effluents are compared, using a specially design model solution. The effect of typical textile wastewater com-position on the treatment efficiency is discussed. Higher decoloration efficiencies were obtained with both AOPs tested in this work, being slightly higher with ozonation. TOC was only partially removed, be-ing more efficient photo-Fenton than ozonation.Fil: Hanela, Sergio Daniel. Instituto Nacional del Agua. Gerencia de Programas y Proyectos. Centro de Tecnologia del Uso del Agua.; ArgentinaFil: Fantoni, Sofía. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Cainzos, Verónica Jorgelina. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Ávalos, J.I.. Instituto Nacional del Agua. Gerencia de Programas y Proyectos. Centro de Tecnologia del Uso del Agua.; ArgentinaFil: Diaz, S.N.. Instituto Nacional del Agua. Gerencia de Programas y Proyectos. Centro de Tecnologia del Uso del Agua.; ArgentinaFil: Romero, E.. Instituto Nacional del Agua. Gerencia de Programas y Proyectos. Centro de Tecnologia del Uso del Agua.; ArgentinaFil: Vezzoni, A.I.. Instituto Nacional del Agua. Gerencia de Programas y Proyectos. Centro de Tecnologia del Uso del Agua.; ArgentinaFil: Candal, Roberto Jorge. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Miro, Eduardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

    Musicoterapia en una Unidad de Cuidados Intensivos Neonatales: experiencia benéfica para el binomio

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    ResumenIntroducciónDesde hace varios años se está utilizando la música como herramienta terapéutica y preventiva en la neonatología, se han documentado en un gran número de artículos de investigación, sin embargo, en México esta técnica es poco utilizada.ObjetivoMejorar las condiciones de los neonatos atendidos en una Unidad de Cuidados Intensivos (UCIN) y sus familiares, mediante el uso de musicoterapia, para minimizar el estrés y los daños colaterales.Materiales y métodosUn grupo de 2 neonatólogos, 3 residentes de pediatría, 10 enfermeras y un concertista profesional de violín, llevaron a cabo 6 sesiones musicales semanales en la Unidad de Cuidados Intensivos Neonatales Externos del Hospital Civil de Guadalajara. Durante el concierto se valoró individualmente a cada neonato, registrando los signos vitales por monitorización electrónica, además se registró el estado anímico de los familiares.ResultadosDurante las sesiones de música los neonatales no presentaron cambios significativos en sus constantes vitales, en el personal de la UCIN y en los padres de recién nacidos hospitalizados se vieron efectos benéficos, refiriendo disminución del estrés y altos índices de satisfacción.ConclusionesLa música puede tener un efecto positivo como terapia coadyuvante en neonatos de alto riesgo, principalmente en prematuros. Se recomienda difundir y aplicar esta metodología en las UCIN del país.AbstractIntroductionSince several years ago, music has been used as a therapeutic and preventive tool in neonatology. A great number of research papers have been written on the subject; however, this technique is rarely used in Mexico.ObjectiveTo improve the condition of neonates at Neonatal Intensive Care Units (NICU) and their relatives, in order to minimize any stress and collateral damage.Material and methods: A group of two neonatologists, 3 residents, 10 nurses and a professional concert violinist, conducted six weekly music sessions in the Outpatient Neonatal Intensive Care Unit (ONICU) of our institution. During the concert, we individually assessed each newborn, recording vital signs through electronic monitoring; additionally, we recorded the mood of any other family members present.ResultsDuring the music sessions, the neonatal patients showed no significant changes in vital signs; yet, ONICU staff and the parents/relatives of hospitalized newborns showed beneficial effects, reporting decreased stress and high levels of satisfaction.ConclusionsMusic can have a positive effect as adjunctive therapy in high-risk newborns, especially in premature babies. We therefore recommend applying this methodology in the ONICU

    Reproductive aspects of the male jaguar (Panthera onca): A review

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    Objective: To describe the anatomy, morphology and physiology of the reproductive system of male jaguars, as well as assisted reproduction techniques. Methodology: A literature review on the anatomy and morphology of the jaguar´s reproductive system, its physiological characteristics and assisted reproduction techniques were carried out to document relevant information on the topic. Results: With this review, basic aspects of the morphology of the reproductive system of the jaguars are disclosed, although scarce knowledge is available on their reproduction. The advances in the collection, evaluation and cryopreservation of semen of this feline are shown, in addition to assisted reproduction techniques such as artificial insemination and in vitro fertilization, which have a great potential to safeguard the species. Study limitations: The jaguar, an emblematic species of Latinamerica, is an endangered species, like other wild felids species as ocelot (Leopardus pardalis) and margay (Leopardus wiedii), which makes it necessary to have a national assisted reproduction program. However, for this to be possible, information about their reproductive physiology is necessary, which is complicated in wild animals and even more so because the reproductive mechanisms greatly differ between felids species. There is scarce information in this regard from its free-living or Mexican zoos, it is for this reason necessary to generate such information. Conclusions: It is necessary to continue working on designing protocols for artificial insemination and other assisted reproduction techniques such as in-vitro fertilization specifically for male Panthera onca
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