1,135 research outputs found

    Lyapunov exponents from CHUA's circuit time series using artificial neural networks

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    In this paper we present the general problem of identifying if a nonlinear dynamic system has a chaotic behavior. If the answer is positive the system will be sensitive to small perturbations in the initial conditions which will imply that there is a chaotic attractor in its state space. A particular problem would be that of identifying a chaotic oscillator. We present an example of three well known different chaotic oscillators where we have knowledge of the equations that govern the dynamical systems and from there we can obtain the corresponding time series. In a similar example we assume that we only know the time series and, finally, in another example we have to take measurements in the Chua's circuit to obtain sample points of the time series. With the knowledge about the time series the phase plane portraits are plotted and from them, by visual inspection, it is concluded whether or not the system is chaotic. This method has the problem of uncertainty and subjectivity and for that reason a different approach is needed. A quantitative approach is the computation of the Lyapunov exponents. We describe several methods for obtaining them and apply a little known method of artificial neural networks to the different examples mentioned above. We end the paper discussing the importance of the Lyapunov exponents in the interpretation of the dynamic behavior of biological neurons and biological neural networks

    Heavier alkali-metal gallates as platforms for accessing functionalized abnormal NHC carbene-gallium complexes

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    By sequentially treating the unsaturated carbene IPr (IPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene) with heavier alkali-metal alkyls NaR or KR (R = CH2SiMe3) and GaR3, novel heteroleptic gallates 1 and 2 have been prepared. Incorporating anionic NHC ligands, these bimetallic complexes react selectively with electrophilles to afford neutral abnormal NHC Ga complexes under mild conditions

    El diseño de un programa de formación ambiental con enfoque intertransversal / Designing an environmental training program from an inter-transversal approach

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    A partir de la sustentación del concepto de intertransversalidad en una investigación anterior  y  sobre  la base de las deficiencias detectadas, se propone un programa de formación ambiental para estudiantes  de los cursos regulares de la Universidad de Ciencias Pedagógicas “José  Martí” de Camagüey. El programa está orientado a la protección del medio ambiente y al desarrollo sostenible y se caracteriza por su enfoque intertransversal y carácter teórico-práctico. Por su contenido y enfoque  contribuye a un mejor desempeño profesional pedagógico-ambiental de los docentes en formación y en ejercicio. El programa fue valorado mediante el criterio de expertos e introducido en la práctica, con resultados satisfactorios, en doce grupos estudiantiles, de ambos tipos de cursos y de diferentes carreras con sus correspondientes adecuaciones.ABSTRACT An environmental educational program is devised based on the notion of inter-transversability —as described in a prior research and considering the shortcomings of teachers of sciences training process—. The program is aimed at environmental protection sustainable development; it is characterized by its inter-transversal approach, its theoretical and practical character, and its contribution to teachers’ educational and environmental professional performance. The program has been in use in 12 classes and assessed by means consulting experts on the topic

    Optical calibration facility at the Izaña Atmospheric Research Center [Póster]

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    Póster presentado en: 37th Annual European Meeting on Atmospheric Studies by Optical Methods, celebrado en 2010 en Valladolid.Financial supports from the Spanish MICIIN (ref.CGL2008-05939-CO3-00/CLIandCGL2009-09740) and from the GR-220 Project of the Junta de Castilla y León are gratefully acknowledged

    Laboratorio de calibración óptica del Centro de Investigación Atmosférica de Izaña

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    Financial supports from the Spanish MICIIN (ref. CGL2008‐05939‐CO3‐00/CLI and CGL 2009‐ 09740) and from the GR‐220 Project of the Junta de Castilla y León are gratefully acknowledged

    How Donor and Surgical Factors Affect the Viability and Functionality of Human Hepatocytes Isolated From Liver Resections

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    Liver resections are a significant source of primary human hepatocytes used mainly in artificial liver devices and pharmacological and biomedical studies. However, it is not well known how patient-donor and surgery-dependent factors influence isolated hepatocytes’ yield, viability, and function. Hence, we aimed to analyze the impact of all these elements on the outcome of human hepatocyte isolation. Patients and methods: Hepatocytes were isolated from liver tissue from patients undergoing partial hepatectomy using a two-step collagenase method. Hepatocyte viability, cell yield, adhesion, and functionality were measured. In addition, clinical and analytical patient variables were collected and the use or absence of vascular clamping and its type (continuous or intermittent) plus the ischemia times during surgery. Results: Malignant disease, previous chemotherapy, and male gender were associated with lower hepatocyte viability and isolation cell yields. The previous increase in transaminases was also associated with lower yields on isolation and lower albumin production. Furthermore, ischemia secondary to vascular clamping during surgery was inversely correlated with the isolated hepatocyte viability. An ischemia time higher than 15 min was related to adverse effects on viability. Conclusion: Several factors correlated with the patient and the surgery directly influence the success of human hepatocyte isolation from patients undergoing liver resection

    Allogeneic adipose tissue-derived mesenchymal stem cells in ischaemic stroke (AMASCIS-02): A phase IIb, multicentre, double-blind, placebo-controlled clinical trial protocol

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    Introduction Stroke is a serious public health problem, given it is a major cause of disability worldwide despite the spread of recanalisation therapies. Enhancement of brain plasticity with stem cell administration is a promising innovative therapy to reduce sequelae in these patients. Methods and analysis We have developed a phase IIb, multicentre, randomised, double-blind, placebo-controlled clinical trial protocol to evaluate the safety and efficacy of intravenous administration of allogeneic adipose tissue-derived mesenchymal stem cells (AD-MSCs) in patients with acute ischaemic stroke, concurrently with conventional stroke treatment. Thirty patients will be randomised on a 1:1 basis to receive either intravenous placebo or allogeneic AD-MSCs as soon as possible within the first 4 days from stroke symptom onset. Patients will be followed up to 24 months after randomisation. The primary objective is the safety assessment of early intravenous administration of allogeneic AD-MSCs by reporting all adverse events and neurological or systemic complications in both treatment groups. Secondary objectives assess efficacy of early intravenous AD-MSC treatment in acute ischaemic stroke by evaluating changes in the modified Rankin Scale and the National Institutes of Health Stroke Scale throughout the follow-up period. In addition, brain repair biomarkers will be measured at various visits. Ethics and dissemination This clinical trial has been approved by the Clinical Research Ethics Committee of La Paz University Hospital (Madrid, Spain) and by the Spanish Agency of Medication and Health Products and has been registered in Eudra CT (2019-001724-35) and ClinicalTrials.gov (NCT04280003). Study results will be disseminated through peer-reviewed publications in Open Access format and at conference presentationsThis clinical trial has been promoted by the La Paz University Hospital Institute for Health Research—IdiPAZ (La Paz University Hospital—Universidad Autónoma de Madrid) and sponsored from a competitive grant from the Carlos III Health Institute Healthcare Research Fund, and cofunded by the European Regional Development Fund (ERDF) 'A way to make Europe'/'Investing in your future' (PIC18/00016). This clinical trial has been supported by Plataforma Española de Investigación Clínica y Ensayos Clínicos, SCReN (Spanish Clinical Research Network), funded by Carlos III Health Institute-General Subdirection for Evaluation and Promotion of Research, research PT17/0017/0013; State Plan for Scientific Investigation, Technology and Innovation (2017–2020) and cofunded by European Regional Development Fund/European Social fund 'A way to make Europe'/'Investing in your future' (grant ID PT17/0017/0013

    Erratum to:The Neurocognitive Architecture of Individual Differences in Math Anxiety in Typical Children (Scientific Reports, (2018), 8, 1, (8500), 10.1038/s41598-018-26912-5)

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    A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper

    A systematic approach for peptide characterization of B-cell receptor in chronic lymphocytic leukemia cells

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    A wide variety of immunoglobulins (Ig) is produced by the immune system thanks to different mechanisms (V(D)J recombination, somatic hypermutation, and antigen selection). The profiling of Ig sequences (at both DNA and peptide levels) are of great relevance to developing targeted vaccines or treatments for specific diseases or infections. Thus, genomics and proteomics techniques (such as Next- Generation Sequencing (NGS) and mass spectrometry (MS)) have notably increased the knowledge in Ig sequencing and serum Ig peptide profiling in a high-throughput manner. However, the peptide characterization of membrane-bound Ig (e.g., B-cell receptors, BCR) is still a challenge mainly due to the poor recovery of mentioned Ig. Herein, we have evaluated three different sample processing methods for peptide sequencing of BCR belonging to chronic lymphocytic leukemia (CLL) B cells identifying up to 426 different peptide sequences (MS/MS data are available via ProteomeXchange with identifier PXD004466). Moreover, as a consequence of the results here obtained, recommended guidelines have been described for BCR-sequencing of B-CLL samples by MS approaches. For this purpose, an in-house algorithm has been designed and developed to compare the MS/MS results with those obtained by molecular biology in order to integrate both proteomics and genomics results and establish the steps to follow when sequencing membrane-bound Ig by MS/MS.We gratefully acknowledge financial support from the Spanish Health Institute Carlos III (ISCIII) for the grants: FIS PI11/02114 and FIS PI114/01538. We also acknowledge Fondos FEDER (EU) and Junta Castilla León (grant BIO/SA07/15). This work has been also sponsored by Fundación Solórzano (FS/23-2015). The Proteomics Unit belongs to ProteoRed, PRB2-ISCIII, supported by grant PT13/0001, of the PE I+D+I 2013-2016, funded by ISCIII and FEDER. The authors would like to thank all the clinicians and technicians in the Cytometry and Cell Purification Services of the University of Salamanca, the Spanish National DNA Bank (Banco Nacional de DNA Carlos III, University of Salamanca) and the Genomic Unit of Cancer Research Centre (IBMCC, USAL-CSIC) for their support in the data collection for the preparation of this manuscript. P.D. is supported by a JCYL-EDU/346/2013 Ph.D. scholarship.Peer Reviewe
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