121 research outputs found

    Inferring criticality in neural networks

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    Generalized Harmonic Functions and the Dewetting of Thin Films

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    This paper describes the solvability of Dirichlet problems for Laplace's equation when the boundary data is not smooth enough for the existence of a weak solution in H1Ω. Scales of spaces of harmonic functions and of boundary traces are defined and the solutions are characterized as limits of classical harmonic functions in special norms. The generalized harmonic functions, and their norms, are defined using series expansions involving harmonic Steklov eigenfunctions on the domain. It is shown that the usual trace operator has a continuous extension to an isometric isomorphism of specific spaces. This provides a characterization of the generalized solutions of harmonic Dirichlet problems. Numerical simulations of a model problem are described. This problem is related to the dewetting of thin films and the associated phenomenology is describe

    The geometric approach to human stress based on stress-related surrogate measures.

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    We present a predictive Geometric Stress Index (pGSI) and its relation to behavioural Entropy ([Formula: see text]). [Formula: see text] is a measure of the complexity of an organism's reactivity to stressors yielding patterns based on different behavioural and physiological variables selected as Surrogate Markers of Stress (SMS). We present a relationship between pGSI and [Formula: see text] in terms of a power law model. This nonlinear relationship describes congruences in complexity derived from analyses of observable and measurable SMS based patterns interpreted as stress. The adjective geometric refers to subdivision(s) of the domain derived from two SMS (heart rate variability and steps frequency) with respect to a positive/negative binary perceptron based on a third SMS (blood oxygenation). The presented power law allows for both quantitative and qualitative evaluations of the consequences of stress measured by pGSI. In particular, we show that elevated stress levels in terms of pGSI leads to a decrease of the [Formula: see text] of the blood oxygenation, measured by peripheral blood oxygenation SpO2 as a model of SMS

    Biases in Inverse Ising Estimates of Near-Critical Behaviour

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    Inverse Ising inference allows pairwise interactions of complex binary systems to be reconstructed from empirical correlations. Typical estimators used for this inference, such as Pseudo-likelihood maximization (PLM), are biased. Using the Sherrington-Kirkpatrick (SK) model as a benchmark, we show that these biases are large in critical regimes close to phase boundaries, and may alter the qualitative interpretation of the inferred model. In particular, we show that the small-sample bias causes models inferred through PLM to appear closer-to-criticality than one would expect from the data. Data-driven methods to correct this bias are explored and applied to a functional magnetic resonance imaging (fMRI) dataset from neuroscience. Our results indicate that additional care should be taken when attributing criticality to real-world datasets

    Testing the antimicrobial activity of essential oils

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    The vapor phase of some essential oils proved to have antimicrobial activity. Utilization of the vapor phase of Eos is presently understood as one of the possible alternatives to synthetic food preservatives which could be used in the future. However, testing the vapor phase of EOs against microorganisms causing food-borne diseases (e.g. Salmonella enteritidis or Staphylococcus aureus) or food spoilage is relatively new. Consequently, due to the large number of known EOs, research on their antimicrobial activity is still largely in the phase of in vitro rather than in vivo testing. Moreover, no standard and reliable method for fast screening of a wide range of samples exists. Thus, the aim of this study is to show results concerning tests of the antimicrobial activity of EOs against S. enteritidis or S. aureus, which were conducted by two modifications of the disc volatilization method we developed. The lately developed method has the potential to become widely used for fast screening of EO antimicrobial activity in the vapor phase

    The World Summit of Harmonization on Traditional, Alternative and Complementary Medicine (TACM) in Lima, Peru

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    The World Summit of Harmonization on Traditional, Alternative and Complementary Medicine (TACM) was held in Lima, Peru, November 7–11, 2007, with almost 600 worldwide participants. This meeting was organized by Peruvian Medical College, the institution that affiliates and authorizes all physicians to practice medicine in Peru. The meeting included seven sections starting with an overview on the current status of the TACM. The second section included experiences from different countries on regulations and quality control in products and services used in the TACM. The worldwide experience of education and training in TACM was a very important part of the meeting in which speakers from Spain, Germany, Argentina, Italy, Brazil, Cuba and Peru shared their experience. The meeting included topics on homeopathy, acupuncture, mind–body medicine, neural therapy, chiropraxis, among others. Two final sessions were related to the ways of linking Traditional medicine to the national Health Systems in the Latin America countries and also the association between bio-commerce and TACM including intellectual properties and bio-piracy

    Secreted Enzyme-Responsive System for Controlled Antifungal Agent Release

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    [EN] Essential oil components (EOCs) such as eugenol play a significant role in plant antimicrobial defense. Due to the volatility and general reactivity of these molecules, plants have evolved smart systems for their storage and release, which are key prerequisites for their efficient use. In this study, biomimetic systems for the controlled release of eugenol, inspired by natural plant defense mechanisms, were prepared and their antifungal activity is described. Delivery and antifungal studies of mesoporous silica nanoparticles (MSN) loaded with eugenol and capped with different saccharide gates-starch, maltodextrin, maltose and glucose-against fungus Aspergillus niger-were performed. The maltodextrin- and maltose-capped systems show very low eugenol release in the absence of the fungus Aspergillus niger but high cargo delivery in its presence. The anchored saccharides are degraded by exogenous enzymes, resulting in eugenol release and efficient inhibition of fungal growth.This research was funded by the project NutRisk (Project No: CZ.02.1.01/0.0/0.0/16_019/0000845), the Spanish Government (projects RTI2018-100910-B-C41, RTI2018-101599-B-C22-AR and RTI2018-101599-B-C21-AR (MINECO/FEDER)) and the GeneralitatValenciana (project PROME-TEO 2018/024); by the National Agency for Agricultural Research of the Ministry of Agriculture of the Czech Republic under project Biostore QK21010064; and by the Research Infrastructure METROFOOD-CZ supported by the Ministry of Education, Youth, and Sports of the Czech Republic under project number LM201810. A.B. thanks the Spanish Government for financial support.Bernardos Bau, A.; Bozik, M.; Montero, A.; Pérez-Esteve, É.; García-Casado, E.; Lhotka, M.; Frankova, A.... (2021). Secreted Enzyme-Responsive System for Controlled Antifungal Agent Release. Nanomaterials. 11(5):1-14. https://doi.org/10.3390/nano11051280S11411

    Antifungal effect of essential oil components against Aspergillus niger when loaded into silica mesoporous supports

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    BACKGROUND: Essential oil components (EOCs) are known for their antifungal properties; however, their high volatility limits their application as antimicrobial agents. Strategies used for controlling the volatility of EOCs include encapsulation or loading into porous materials. This study evaluated the in vitro antifungal activity of selected EOCs (carvacrol, cinnamaldehyde, eugenol and thymol) against the fungus Aspergillus niger when loaded into MCM-41 and b-cyclodextrin (b-CD). RESULTS: Carvacrol and thymol in Mobil Composition of Matter No. 41 (MCM-41) displayed remarkable enhanced antifungal properties in comparison to the pure or b- CD-encapsulated EOCs. In fact, carvacrol and thymol were able to maintain antifungal activity and inhibit fungal growth for 30 days, suggesting better applicability of these EOCs as natural preservatives. CONCLUSIONS: The sustained antifungal effect of EOCs encapsulated into silica mesoporous supports was described.The authors wish to express their gratitude to the Government of the Czech Republic (Postdok CZU: ESF and MEYS CZ.1.07/2.3.00/30.0040), to CIGA (Project number: 20132024) and to the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic (research project RVO: 61388963). Beth Green is thanked for language control.Bernardos Bau, A.; Marina, T.; Zacek, P.; Pérez-Esteve, É.; Martínez-Máñez, R.; Lhotka, M.; Kourimská, L.... (2015). Antifungal effect of essential oil components against Aspergillus niger when loaded into silica mesoporous supports. Journal of the Science of Food and Agriculture. 95(14):2824-2831. doi:10.1002/jsfa.7022S28242831951

    A gallotannin-rich fraction from Caesalpinia spinosa (Molina) Kuntze displays cytotoxic activity and raises sensitivity to doxorubicin in a leukemia cell line

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    <p>Abstract</p> <p>Background</p> <p>Enhancement of tumor cell sensitivity may help facilitate a reduction in drug dosage using conventional chemotherapies. Consequently, it is worthwhile to search for adjuvants with the potential of increasing chemotherapeutic drug effectiveness and improving patient quality of life. Natural products are a very good source of such adjuvants.</p> <p>Methods</p> <p>The biological activity of a fraction enriched in hydrolysable polyphenols (P2Et) obtained from <it>Caesalpinia spinosa </it>was evaluated using the hematopoietic cell line K562. This fraction was tested alone or in combination with the conventional chemotherapeutic drugs doxorubicin, vincristine, etoposide, camptothecin and taxol. The parameters evaluated were mitochondrial depolarization, caspase 3 activation, chromatin condensation and clonogenic activity.</p> <p>Results</p> <p>We found that the P2Et fraction induced mitochondrial depolarization, activated caspase 3, induced chromatin condensation and decreased the clonogenic capacity of the K562 cell line. When the P2Et fraction was used in combination with chemotherapeutic drugs at sub-lethal concentrations, a fourfold reduction in doxorubicin inhibitory concentration 50 (IC<sub>50</sub>) was seen in the K562 cell line. This finding suggested that P2Et fraction activity is specific for the molecular target of doxorubicin.</p> <p>Conclusions</p> <p>Our results suggest that a natural fraction extracted from <it>Caesalpinia spinosa </it>in combination with conventional chemotherapy in combination with natural products on leukemia cells may increase therapeutic effectiveness in relation to leukemia.</p
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