138 research outputs found

    Recurrent inhibition in the cerebral cortex

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    Neuronal activity can be modulated by endogenous control mechanisms that either facilitate or suppress it. With this idea in mind, we attempted to evaluate and correlate spinal neuronal activity with the amplitude of corticogram (ECoG) event related potentials (ERP) in the presence of nociceptive stimulation in rats. We evaluated the ERP in response to noxious stimuli, endogenous analgesic actions, different frequencies, and heterotopic nociceptive stimulation, as well as in conjunction with recordings from neurons in the spinal cord that are activated by noxious stimuli. Computational tasks enabled us to establish correlations between the amplitude of ERP and neuronal firing of cells in the spinal dorsal horn. Our results show that the ERP amplitude could be modified by previous activity in the cerebral cortex, but the activity in the spinal cord did not change. Previous activity could originate spontaneously or could be driven by sensory stimulation. A recurrent inhibitory cortical action is proposed that could explain the suppression of pain perception during electrical or magnetic transcranial stimulation, as well as during heterotopic stimulation. This study aims to uncover a local recurrent inhibitory cortical action that could modify the sensory information.Postprint (author's final draft

    Modelling stand biomass fractions in Galician Eucalyptus globulus plantations by use of different LiDAR pulse densities

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    [EN] Aims of study: To evaluate the potential use of canopy height and intensity distributions, determined by airborneLiDAR, for the estimation of crown, stem and aboveground biomass fractions.To assess the effects of a reduction in LiDAR pulse densities on model precision.Area of study: The study area is located in Galicia, NW Spain. The forests are representative of Eucalyptus globulusstands in NW Spain, characterized by low-intensity silvicultural treatments and by the presence of tall shrub.Material and methods: Linear, multiplicative power and exponential models were used to establish empiricalrelationships between field measurements and LiDAR metrics.A random selection of LiDAR returns and a comparison of the prediction errors by LiDAR pulse density factorwere performed to study a possible loss of fit in these models.Main results: Models showed similar goodness-of-fit statistics to those reported in the international literature. R2ranged from 0.52 to 0.75 for stand crown biomass, from 0.64 to 0.87 for stand stem biomass, and from 0.63 to 0.86for stand aboveground biomass. The RMSE/MEAN · 100 of the set of fitted models ranged from 17.4% to 28.4%.Models precision was essentially maintained when 87.5% of the original point cloud was reduced, i.e.a reductionfrom 4 pulses m–2to 0.5 pulses m–2.Research highlights: Considering the results of this study, the low-density LiDAR data that are released by theSpanish National Geographic Institute will be an excellent source of information for reducing the cost of forestinventoriesSIGalician Government, Xunta de Galicia, DirecciónXeral de Montes(09MRU022291PR); Norvento (Mul-tinational energy company) (PGIDT09REM023E);Galician Government, Dirección Xeral de Ordenacióne Calidade do Sistema Universitario de Galicia (Con-sellería de Educación e Ordenación Universitaria)and European Social Fund (Official Journal of Galicia –DOG nº 9, p. 2246, exp. 2011/14

    Evolutionary feature selection to estimate forest stand variablesusing LiDAR

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    Light detection and ranging (LiDAR) has become an important tool in forestry. LiDAR-derived models are mostly developed by means of multiple linear regression (MLR) after stepwise selection of predictors. An increasing interest in machine learning and evolutionary computation has recently arisen to improve regression use in LiDAR data processing. Although evolutionary machine learning has already proven to be suitable for regression, evolutionary computation may also be applied to improve parametric models such as MLR. This paper provides a hybrid approach based on joint use of MLR and a novel genetic algorithm for the estimation of the main forest stand variables. We show a comparison between our genetic approach and other common methods of selecting predictors. The results obtained from several LiDAR datasets with different pulse densities in two areas of the Iberian Peninsula indicate that genetic algorithms perform better than the other methods statistically. Preliminary studies suggest that a lack of parametric conditions in field data and possible misuse of parametric tests may be the main reasons for the better performance of the genetic algorithm. This research confirms the findings of previous studies that outline the importance of evolutionary computation in the context of LiDAR analisys of forest data, especially when the size of fieldwork datatasets is reduced.Ministerio de Ciencia y Tecnología TIN2007- 68084-C-00Ministerio de Ciencia y Tecnología TIN2011-28956-C02Xunta de Galicia 09MRU022291PXunta de Galicia CGL2011-30285-C02-02Xunta de Galicia FP7-SME-2011-BS

    Definición de especificaciones de diseño para un dispositivo que prevenga y trate el síndrome del túnel carpiano

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    1. Título de la investigación, 2. Problema de investigación, 2.1 Descripción del problema, 2.2 Formulación del problema, 3. Objetivos de la investigación, 3.1 Objetivo general, 3.2 Objetivos específicos, 4. Justificación y delimitación de la investigación, 4.1 Justificación, 4.2 Delimitación, 5. Marco de referencia de la investigación, 5.1 Marco teórico, 5.2 Marco conceptual, 5.2.1 Factores del riesgo del túnel carpiano, 5.3 Marco legal, 5.3.1 Ley 31 de 1995, 5.3.2 Ley 776 del 2002, 5.3.3 Decreto 1477 del 2014, 5.3.4 Resolución 2844 de 2007, 5.3.5 Proyecto de Acuerdo 294 de 2006, 6. Metodología 6.1 Tipo de investigación, 6.2 Diseño metodológico, 7. Resultados, 7.1 Fase I. Lluvia de ideas, 7.2 Fase 2 selección de dispositivo, 7.3 Fase 3 especificación 1: Ergonomía, 7.4 Fase 4 Especificación 2: Vibración, 7.4.1 Magnitud, 7.4.2 Frecuencia, 7.4.3 Duración, 7.5 Fase 5. Especificación 3: ventilación, 7.5.1 Ventilador con refrigeración líquida, 7.5.1.1 Funcionalidad mecánica, 7.6 Fase 6 Materiales, 7.6.1 Eléctrica, 7.6.2 Materiales, 7.7 Fase 7 Vistas, 7.7.1 Planos de diseño, Conclusiones, Referencias,PregradoIngeniero en IndustrialIngeniería Industria

    Optimization of ciprofloxacin degradation in wastewater by homogeneous sono-Fenton process at high frequency

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    Emerging pollutants such as pharmaceuticals have been focusing international attention for a few decades. Ciprofloxacin (CIP) is a common drug that is widely found in hospital and wastewater treatment plants effluents, as well as in rivers. In this work, the feasibility of CIP degradation by ultrasound process at high frequency is discussed and sonolysis, sonolysis with hydrogen peroxide and sono-Fenton are evaluated. The amounts of hydrogen peroxide and ferrous ions (Fe2+) needed were optimized using response surface methodology. Best results were obtained with the sono-Fenton process resulting in a total pharmaceutical degradation within 15 min and a mineralization greater than 60% after 1 h. Optimal conditions were tested on a real matrix from a municipal wastewater treatment plant. Even if the degradation of the pollutants by sono-Fenton was hampered, the removal efficiency of both CIP and total organic carbon (TOC) is interesting as an increase in the biodegradability of the wastewater is found. These results show that sono-Fenton oxidation can be a promising pretreatment process for pharmaceutical-containing wastewaters

    Malignant nerve sheath tumor involving glossopharyngeal, vagus and spinal nerve with intracranial-extracranial extension and systemic metastases in a patient with type 1 neurofibromatosis: A case report

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    AbstractIntroductionIntracranial malignant peripheral nerve sheath tumors are an extremely rare pathology with a high morbidity and mortality. Epidemiological, clinical and prognostic data are scarce and with little certainty in the literature. The aim of this paper is to report for first time in English literature, the case of a patient with type 1 neurofibromatosis, who presented a malignant peripheral nerve sheath tumor that involved the left glossopharyngeal, vagus and spinal nerves with intracranial and extracranial extension through jugular foramen and systemic metastases.Presentation of caseA 37 years-old female patient with malnutrition and Villaret́s syndrome. It was confirmed by brain magnetic resonance imaging and PET-CT the presence of a neoplasic lesion which was radiologically compatible with malignant peripheral nerve sheath tumor with systemic metastases. Partial surgical resection was performed; the patient postoperative course was without significant clinical improvement but with added peripheral facial palsy. The patient did not accept adjuvant management because of personal reasons.Discussion and conclusionBehavior therapy is unclear due to the low frequency of the disease and the lack of case series, representing a challenge for the physician in its approach and a poor prognosis for the patient

    An approach for evaluating the bioavailability and risk assessment of potentially toxic elements using edible and inedible plants—the Remance (Panama) mining area as a model

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    Mining affects the environment, particularly through the persistence of accumulation of tailings materials; this is aggravated under tropical climatic conditions, which favours the release of potentially toxic elements (PTEs) bioavailable to the local flora and fauna and supposing a risk to human health. The Remance gold mine (Panamá), exploited intermittently for more than 100 years, and has remained derelict for over 20 years. Within the area live farmers who carry out subsistence agriculture and livestock activities. The objective of this study has been to study the transference of PTEs in the local agricultural soil-plants system, with the goal of identifying their bioavailability to perform a human risk assessment. The results obtained of the Bioaccumulation coefficient in local plants show very weak to strong absorption of As (< 0.001–1.50), Hg (< 0.001–2.38), Sb (0.01–7.83), Cu (0.02–2.89), and Zn (0.06–5.32). In the case of Cu in grass (18.3 mg kg−1) and plants (16.9 mg kg−1) the concentrations exceed the maximum authorised value in animal nutrition for ruminants (10 mg kg−1). The risk to human health for edible plants exceeds the non-carcinogenic risk for rice, corn, cassava, and tea leaves for Sb (HQ 19.450, 18.304, 6.075, 1.830, respectively), the carcinogenic risk for Cu (CR = 2.3 × 10–3, 7.7 × 10 −4, 1.1 × 10–3, 1.0 × 10–3, respectively), and the carcinogenic risk for As in rice, corn and tea leaves (CR = 8 × 10–5, 3 × 10–5, 3 × 10–5, respectively). Urgent measures are needed to alleviate these effects.Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUECRUE-CSICNational Secretary of Science and Technology (Panamá)Institute for the Training and Use of Human Resources (Panamá)Universidad de Castilla La Manchapu

    Gastric antral vascular ectasia. Clinical presentation and therapeutic management

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    Gastric antral vascular ectasia is an infrequent cause of high gastric hemorrhage, responsible of the 4% of high gastric non-variceal hemorrhages. The diagnosis is based on endoscopic findings and its most accepted treatment is argon plasma coagulation. It is presented a case of a woman with recurrent digestive hemorrhages in the form of melena and anemia, who was performed a high digestive endoscopy with resulting a diagnosis of vascular ectasia of the gastric antro. Later she was treated satisfactorily with argon plasma coagulation without complications. The resent work is aimed at reviewing an unusual cause of digestive bleeding and its treatment
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