495 research outputs found

    Irrationality and quasiperiodicity in driven nonlinear systems

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    We analyse the relationship between irrationality and quasiperiodicity in nonlinear driven systems. To that purpose we consider a nonlinear system whose steady-state response is very sensitive to the periodic or quasiperiodic character of the input signal. In the infinite time limit, an input signal consisting of two incommensurate frequencies will be recognised by the system as quasiperiodic. We show that this is in general not true in the case of finite interaction times. An irrational ratio of the driving frequencies of the input signal is not sufficient for it to be recognised by the nonlinear system as quasiperiodic, resulting in observations which may differ by several orders of magnitude from the expected quasiperiodic behavior. Thus, the system response depends on the nature of the irrational ratio, as well as the observation time. We derive a condition for the input signal to be identified by the system as quasiperiodic. Such a condition also takes into account the sub-Fourier response of the nonlinear system.Comment: accepted in Phys. Rev. Let

    Técnicas de encaminamiento en redes ad-hoc basadas en criterios de potencia y batería

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    Las redes ad hoc están formadas únicamente por terminales móviles que funcionan a partir de baterías, es decir, no hay estaciones base. El consumo de energía es, por lo tanto, un punto muy importante ala hora de diseñar la red. Paramax.imizar el tiempo de vida de una red ad hoc, el consumo de energía tiene que ser distribuido de forma equitati va entre el conjunto de nodos que la forman, y a la vez ha de rIÚnirnizarse el consumo total de energía para cada transmisión. Los algoritmosdeencarninarniento clásicos para ad hoc no tienen en cuenta la energía y por tanto no consiguen maximizar el tiempo de vida de la red. En este artículo se hace un estudio del estado del arte en métricas de encaminamiento que tengan en cuenta la batería al seleccionar las rutas y se proponen nuevas métricas al respecto. Dichas métricas se comparan mediante simulación intentando llegar a un compromiso entre parámetros como el tiempo de vida de la red y la calidad de servicio, entre otros.Peer Reviewe

    EUropean prospective cohort study on Enterobacteriaceae showing REsistance to CArbapenems (EURECA): a protocol of a European multicentre observational study

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    Introduction: The rapid worldwide spread of carbapenem-resistant Enterobacteriaceae (CRE) constitutes a major challenge. The aim of the EUropean prospective cohort study on Enterobacteriaceae showing REsistance to CArbapenems (EURECA), which is part of the Innovative Medicines Initiative Joint Undertaking (IMI JU) funded COMBACTE-CARE project, is to investigate risk factors for and outcome determinants of CRE infections to inform randomised clinical trial designs and to provide a historical cohort that could eventually be used for future comparisons with new drugs targeting CRE. Methods: A multicentre (50 sites), multinational (11 European countries), analytical observational project was designed, comprising 3 studies. The aims of study 1 (a prospective cohort study) include characterising the features, clinical management and outcomes of hospitalised patients with intra-abdominal infection, pneumonia, complicated urinary tract infections and bloodstream infections caused by CRE (202 patients in each group). The main outcomes will be 30-day all-cause mortality and clinical response. Study 2 (a nested case–control study) will identify the risk factors for target infections caused by CRE; 248 selected patients from study 1 will be matched with patients with carbapenem-susceptible Enterobacteriaceae (1:1) and with hospitalised patients (1:3) and will provide a historical cohort of patients with CRE infections. Study 3 (a matched cohort study) will follow patients in study 2 in order to assess mortality, length of stay and hospital costs associated with CRE. All patients will be followed for 30 days. Different, up-to-date statistical methods will be applied to come to unbiased estimates for all 3 studies. Ethics and dissemination: Before-study sites will be initiated, approval will be sought from appropriate regulatory agencies and local Ethics Committees of Research or Institutional Review Boards (IRBs) to conduct the study in accordance with regulatory requirements. This is an observational study and therefore no intervention in the diagnosis, management or treatment of the patients will be required on behalf of the investigation. Any formal presentation or publication of data collected from this study will be considered as a joint publication by the participating physician(s) and will follow the recommendations of the International Committee of Medical Journal Editors (ICMJE) for authorship.Innovative Medicine Initiative (IMI)European Union's Seventh Framework Programme (FP7)Spanish Network for Research in Infectious Diseases [REIPI RD12/0015, RD16/2016

    Aphicidal activity of farnesol against the green peach aphid – Myzus persicae

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    BACKGROUND: Myzus persicae (Hemiptera: Aphididae) is considered one of most important agricultural pests in the world. It is one of the main pests in protected pepper crops under glasshouse conditions in Southeastern Spain, but its control is limited as a consequence of the few available authorized insecticides and their incompatibility with the natural enemies. Some essential oils and pure compounds such as anise (Pimpinella anisum) or farnesol are repellent and/or toxic to aphids. Their use as a botanical insecticides can be an alternative for aphid control in pepper. RESULTS: The effect of farnesol was evaluated against M. persicae in a new bioassay developed to test the contact effect (aqueous formulation of the products) on aphids in laboratory conditions. Aniseed essential oil, geraniol and (Z)-jasmone at 0.6% causes an aphid mortality of >50%; and farnesol was the most effective (93.67% mortality). Farnesol nanoemulsions between 0.2% and 0.6% were formulated with an IKA-Labor Pilot dispersing machine (7940 rpm for 10 min) using Tween 80 as a surfactant. These formulations were tested on field experiments (glasshouse conditions) on pepper crops for 2 years. Foliar applications of farnesol at a concentration of 0.4% in field conditions causes a high reduction in aphid populations, with efficacies of ≈70–80% with respect to the control, similar to or even higher than the efficacy of the reference pyrethrin insecticide. CONCLUSION: Farnesol showed a great aphicidal effect against M. persicae. The use of this molecule in integrated pest management programs combined with natural enemies is a good option for future control of M. persicae

    Aniseed essential oil botanical insecticides for the management of the currant-lettuce aphid

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    Nasonovia ribisnigri Mosley (Hemiptera: Aphididae) is the most damaging aphid species of lettuce grown in open fields. Populations of N. ribisnigri are developing resistance to insecticides, making their control difficult. Botanicals are an alternative for pest control. Aniseed (Pimpinella anisum L.) is a relevant crop in the production of essential oils. The effect of aqueous nano-formulations of this oil and its main compound (E)-anethole were tested against N. ribisnigri in a growth chamber, a greenhouse (in spring for two years, 2019 and 2020) and in the open field in a plot in the Southeast of Spain (Torrepacheco, Murcia) in May 2019. Aniseed essential oil nanoemulsions were prepared using a laboratory dispersing machine at a high-speed regime (10 min, 7940 revs/min, 15 ◦C) using Tween80 as a surfactant at a 1:2 ratio. Foliar applications of aniseed essential oil at concentrations of 0.2% and 0.4% (0.1 and 0.2 mL respectively) to lettuce plants infested with homogeneous populations of N. ribisnigri reduced the number of insects compared with the control in the laboratory (efficacies > 50%) and greenhouse (efficacies > 25%, 48 h after treatment) experiments. During the field trial, a reduction in the aphid populations was also produced after the application of the products, without any phytotoxic effects observed on the crop. Likewise, (E)-anethole gave similar results as aniseed essential oil (with efficiencies of up to 47% with respect to the control) without damaging the plant

    Multidisciplinary Approach of Malignant Tumors of the Biliary Tree

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    Biliary tract carcinomas are aggressive tumors that arise from epithelial cells of bile ducts. They present several difficulties in their clinical management. A late initial diagnosis (frequently in the form of locally advanced disease), jaundice, cholangitis, or poor performance status of patients are some of the medical issues that arise in this setting. Another clinical limitation is the lack of robust evidence for many of the standard procedures in this particular scenario. Biliary tumors are lethal tumors, and most of them present in the form of advanced disease or during late evolution. However, we are witnessing some exciting changes in clinical management of tumors of the biliary tract, such as the development of new radiological techniques and novel interventional radiology procedures, the emergence of new radiotherapy modalities, the establishment of standardized chemotherapy regimens, the advance in molecular knowledge, and the development of new treatments directed against therapeutic targets. On the other hand, the most important step for advancing the treatment of these complex diseases is the appearance of multidisciplinary management teams integrating qualified specialists to resolve appropriate treatment challenges. In this chapter, we summarize the most relevant advances in clinical management and new oncologic treatment in biliary tract carcinomas

    Genomic Evolution of Two Acinetobacter baumannii Clinical Strains from ST-2 Clones Isolated in 2000 and 2010 (ST-2_clon_2000 and ST-2_clon_2010)

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    Acinetobacter baumannii is a successful nosocomial pathogen due to its ability to persist in hospital environments by acquiring mobile elements such as transposons, plasmids, and phages. In this study, we compared two genomes of A. baumannii clinical strains isolated in 2000 (ST-2_clon_2000) and 2010 (ST-2_clon_2010) from GenBank project PRJNA308422

    Estrategias Asociativas y su Relación con la Competitividad Empresarial de las PYMES Exportadoras de Confecciones Textiles de la Ciudad de Tacna 2018

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    La presente investigación titulada: Estrategia asociativa y su relación con la competitividad empresarial en las pymes exportadoras de confecciones textiles de la ciudad de Tacna 2018. Tiene como objetivo, explicar la relación que existe entre la estrategia asociativa en la competitividad empresarial en las pymes exportadoras de confecciones textiles de la ciudad de Tacna en el 2018. La investigación es de tipo pura o básica, diseño no experimental. Como instrumento un cuestionario para cada variable, con un total de 35 ítems (dos encuestas). Los resultados muestran que, en la variable Competitividad Empresarial las dimensiones con mayores puntajes son la de gestión financiera e internacionalización con 66% y 54% evaluado con una escala de regular a sus empresas. Para la variable estrategia asociativa las dimensiones con mayor puntaje son aspecto organizacional y comercialización con 63% y 55% considerando que la asociatividad va influenciar en un muy alto grado a cada una de estas dimensiones dentro de su empresa. Finalmente, se obtuvo que la relación entre las dos variables en estudio es directa y significativa con una correlación de Pearson de 64,5%Tesi

    Fueling Plankton Production By a Meandering Frontal Jet: A Case Study For The Alboran Sea (Western Mediterranean)

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    A three dimensional biophysical model is employed to investigate the biological impacts of a meandering frontal jet for which the Alboran Sea of the Western Mediterranean is considered as a case study. The jet is characterized by relatively low density Atlantic water mass issuing from the Gibraltar Strait within the upper 100 m. It flows eastward as a highly nonlinear meandering current around the western and the eastern anticyclonic gyres prior to its attachment to the North African shelf/slope topography of the Algerian basin. Its inherent nonlinearity leads to the development of strong ageostrophic cross-frontal circulation that supplies nutrients into the nutrient-starved euphotic layer and stimulates an effective phytoplankton growth along the jet. The production intensity is strongest in the western basin and decreases eastwards with the gradual weakening of the jet. The stronger production intensity at the subsurface levels suggests the Alboran Sea is likely more productive than envisaged by the satellite chlorophyll data. The Mediterranean water mass away from the jet as well as the interior of the western and eastern anticyclonic gyres remain poorly productive.JRC.H.1-Water Resource
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