771 research outputs found

    Multiple classical limits in relativistic and nonrelativistic quantum mechanics

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    The existence of a classical limit describing interacting particles in a second-quantized theory of identical particles with bosonic symmetry is proved. This limit exists in addition to a previously established classical limit with a classical field behavior, showing that the limit 0\hbar \to 0 of the theory is not unique. An analogous result is valid for a free massive scalar field: two distinct classical limits are proved to exist, describing a system of particles or a classical field. The introduction of local operators in order to represent kinematical properties of interest is shown to break the permutation symmetry under some localizability conditions, allowing the study of individual particle properties.Comment: 13 page

    MiR-146b negatively regulates migration and delays progression of T-cell acute lymphoblastic leukemia

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    © The Author(s) 2016. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/Previous results indicated that miR-146b-5p is downregulated by TAL1, a transcription factor critical for early hematopoiesis that is frequently overexpressed in T-cell acute lymphoblastic leukemia (T-ALL) where it has an oncogenic role. Here, we confirmed that miR-146b-5p expression is lower in TAL1-positive patient samples than in other T-ALL cases. Furthermore, leukemia T-cells display decreased levels of miR-146b-5p as compared to normal T-cells, thymocytes and other hematopoietic progenitors. MiR-146b-5p silencing enhances the in vitro migration and invasion of T-ALL cells, associated with increased levels of filamentous actin and chemokinesis. In vivo, miR-146b overexpression in a TAL1-positive cell line extends mouse survival in a xenotransplant model of human T-ALL. In contrast, knockdown of miR-146b-5p results in leukemia acceleration and decreased mouse overall survival, paralleled by faster tumor infiltration of the central nervous system. Our results suggest that miR-146b-5p is a functionally relevant microRNA gene in the context of T-ALL, whose negative regulation by TAL1 and possibly other oncogenes contributes to disease progression by modulating leukemia cell motility and disease aggressiveness.These studies were supported by Liga Portuguesa Contra o Cancro (Terry Fox Award) and by Fundação para a Ciência e a Tecnologia (project PTDC/BIM-ONC/1548/2012). N.C.C. received an FCT-SFRH PhD fellowship. R.F. and J.T.B. are supported by FCT investigator Starting and Consolidation grants, respectively.info:eu-repo/semantics/publishedVersio

    The unfolded protein response and its potential role in Huntington's disease elucidated by a systems biology approach.

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    Huntington ´s disease (HD) is a progressive, neurodegenerative disease with a fatal outcome. Although the disease-causing gene (huntingtin) has been known for over 20 years, the exact mechanisms leading to neuronal cell death are still controversial. One potential mechanism contributing to the massive loss of neurons observed in the brain of HD patients could be the unfolded protein response (UPR) activated by accumulation of misfolded proteins in the endoplasmic reticulum (ER). As an adaptive response to counter-balance accumulation of un- or misfolded proteins, the UPR upregulates transcription of chaperones, temporarily attenuates new translation, and activates protein degradation via the proteasome. However, persistent ER stress and an activated UPR can also cause apoptotic cell death. Although different studies have indicated a role for the UPR in HD, the evidence remains inconclusive. Here, we present extensive bioinformatic analyses that revealed UPR activation in different experimental HD models based on transcriptomic data. Accordingly, we have identified 53 genes, including RAB5A, HMGB1, CTNNB1, DNM1, TUBB, TSG101, EEF2, DYNC1H1, SLC12A5, ATG5, AKT1, CASP7 and SYVN1 that provide a potential link between UPR and HD. To further elucidate the potential role of UPR as a disease-relevant process, we examined its connection to apoptosis based on molecular interaction data, and identified a set of 40 genes including ADD1, HSP90B1, IKBKB, IKBKG, RPS3A and LMNB1, which seem to be at the crossroads between these two important cellular processes. Remarkably, we also found strong correlation of UPR gene expression with the length of the polyglutamine tract of Huntingtin, which is a critical determinant of age of disease onset in human HD patients pointing to the UPR as a promising target for therapeutic intervention. The study is complemented by a newly developed web-portal called UPR-HD (http://uprhd.sysbiolab.eu) that enables visualization and interactive analysis of UPR-associated gene expression across various HD models

    Parental perspectives on ECEC settings that foster child well-being: A comparison across nine European countries

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    Parents play a vital role in identifying children’s needs for support and Early Childhood Education and Care (ECEC ) features that support children’s well -being.This study examined parental perspectives on features of ECEC that foster young children’s well -being under and above the age of 3 years by interviewing 359 parents across nine European countries (England, Finland, Germany, Greece, Italy, the Netherlands, Norway, Poland, and Portugal). Results revealed that parental perspectives largely converged with quality features discussed in ECEC research. Process quality features were mentioned more frequently than structural features for all children 0- to 6-years-old in almost all countries. However, care -oriented features were mentioned more frequently for under 3 years, and educational-oriented features were mentioned more frequently for the older group. Regarding structural features, patterns of responses across the two age groups were similar in most countries. Age differences were not more pronounced in countries with a split governance system.info:eu-repo/semantics/publishedVersio

    Plunging Airfoil: Reynolds Number and Angle of Attack Effects

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    Natural flight has consistently been the wellspring of many creative minds, yet recreating the propulsive systems of natural flyers is quite hard and challenging. Regarding propulsive systems design, biomimetics offers a wide variety of solutions that can be applied at low Reynolds numbers, achieving high performance and maneuverability systems. The main goal of the current work is to computationally investigate the thrust-power intricacies while operating at different Reynolds numbers, reduced frequencies, nondimensional amplitudes, and mean angles of attack of the oscillatory motion of a NACA0012 airfoil. Simulations are performed utilizing a RANS (Reynolds Averaged Navier-Stokes) approach for a Reynolds number between 8.5×10^3 and 3.4×10^4, reduced frequencies within 1 and 5, and Strouhal numbers from 0.1 to 0.4. The influence of the mean angle-of-attack is also studied in the range of 0º to 10º. The outcomes show ideal operational conditions for the diverse Reynolds numbers, and results regarding thrust-power correlations and the influence of the mean angle-of-attack on the aerodynamic coefficients and the propulsive efficiency are widely explored.Fundação para a Ciência e a Tecnologia e Santander-UBIinfo:eu-repo/semantics/publishedVersio

    Using Self-Organizing Maps for the Behavioral Analysis of Virtualized Network Functions

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    Detecting anomalous behaviors in a network function virtualization infrastructure is of the utmost importance for network operators. In this paper, we propose a technique, based on Self-Organizing Maps, to address such problem by leveraging on the massive amount of historical system data that is typically available in these infrastructures. Indeed, our method consists of a joint analysis of system-level metrics, provided by the virtualized infrastructure monitoring system and referring to resource consumption patterns of the physical hosts and the virtual machines (or containers) that run on top of them, and application-level metrics, provided by the individual virtualized network functions monitoring subsystems and related to the performance levels of the individual applications. The implementation of our approach has been validated on real data coming from a subset of the Vodafone infrastructure for network function virtualization, where it is currently employed to support the decisions of data center operators. Experimental results show that our technique is capable of identifying specific points in space (i.e., components of the infrastructure) and time of the recent evolution of the monitored infrastructure that are worth to be investigated by human operators in order to keep the system running under expected conditions

    Behavioral analysis for virtualized network functions: A som-based approach

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    In this paper, we tackle the problem of detecting anomalous behaviors in a virtualized infrastructure for network function virtualization, proposing to use self-organizing maps for analyzing historical data available through a data center. We propose a joint analysis of system-level metrics, mostly related to resource consumption patterns of the hosted virtual machines, as available through the virtualized infrastructure monitoring system, and the application-level metrics published by individual virtualized network functions through their own monitoring subsystems. Experimental results, obtained by processing real data from one of the NFV data centers of the Vodafone network operator, show that our technique is able to identify specific points in space and time of the recent evolution of the monitored infrastructure that are worth to be investigated by a human operator in order to keep the system running under expected conditions
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