Quantum Baker Maps for Spiraling Chaotic Motion

We define a coupling of two baker maps through a pi/2 rotation both in position and in momentum. The classical trajectories thus exhibit spiraling, or loxodromic motion, which is only possible for conservative maps of at least two degrees of freedom. This loxodromic baker map is still hyperbolic, that is, fully chaotic. Quantization of this map follows on similar lines to other generalized baker maps. It is found that the eigenvalue spectrum for quantum loxodromic baker map is far removed from those of the canonical random matrix ensembles. An investigation of the symmetries of the loxodromic baker map reveals the cause of this deviation from the Bohigas-Giannoni-Schmit conjecture

Estándares territoriales de innovación : análisis de las regiones de Portugal

Competitiveness among regions and innovation dynamics are intimately related and depend on a solid and effective innovation system. This study aims to measure innovativeness in different Portuguese regions and to evaluate the nature of the innovation process and the relationship between innovativeness and its region of origin. To characterize the territorial innovation processes and to identify innovation patterns by regions, it analyzes their main distinctive factors, based on the Community Innovation Survey results for each region. Thus, it compares the Portuguese regions by verifying the existence of subjacent clusters and finding out the characteristics that distinguish the different groups of regions. The results point to the existence of four groups of regions, and the factors identified are related to the innovation process, namely objectives of innovation, sources of innovation, collaborative networks, triple helix performance, and obstacles to innovation.RESUMEN: La competitividad entre las regiones y la dinámica de la innovación están íntimamente relacionadas y dependen de un sistema de innovación sólida y eficaz. Este estudio tiene como objetivo medir la capacidad de innovación en diferentes regiones portuguesas y evaluar la naturaleza del proceso de innovación y la relación entre la capacidad de innovación y su región de origen. Para la caracterización de los procesos de innovación territoriales y identificar estándares de innovación en las regiones, este artículo analiza sus factores distintivos principales, con base en los resultados de las encuestas comunitarias sobre innovación para cada región. Por lo tanto, se comparan las regiones portuguesas mediante la verificación de la existencia de agrupaciones subyacentes y descubrir las características que distinguen a los diferentes grupos de regiones. Los resultados apuntan a la existencia de cuatro grupos de regiones, y los factores identificados están relacionados con el proceso de innovación, es decir, los objetivos de la innovación, las fuentes de innovación, redes de colaboración, el funcionamiento de la triple hélice, y los obstáculos a la innovación.info:eu-repo/semantics/publishedVersio

Radon concentration assessment in water sources of public drinking of Covilhã's county, Portugal

Radon, the heaviest of the noble gases on the periodic table of elements, is a natural radioactive element that can be found on water, soils and rocks. The main goal of this work is to present an evaluation of radon concentration on samples of water, used for human consumption, collected on uranium-rich granitic rock areas. Once the geological features of the sampling region evidence the presence of this natural radionuclides, their slow dissolution steadily increases concentration in ground water. Although, the most important contribution of natural radiation, for most populations, is from inhaled radon (generic term used commonly to refer to the isotope 222Rn), in some circumstances, exposure to natural radionuclides, through drinking water, could exceed acceptable levels, and also present a hazard. Despite the fact that radon can be reduced if the water is boiled, this gas, dissolved in ground water, can be released into the air during household activities such as showering, dishwashing and laundry. So, the short lived radon decay products will contribute to increase the number of those which are present in particles suspended in the indoor air and can be accumulated up to dangerous concentrations. Once the radon progeny emits highly ionizing alpha-radiation, they may cause substantial health damage after long-term exposure. Radon concentration measurements were performed on thirty three samples collected from water wells at different depths and types of aquifers, at Covilhã's County, Portugal with the radon gas analyser DURRIDGE RAD7. Twenty three, of the total of water samples collected, gave, values over 100 Bq/L, being that 1690 Bq/L was the highest measured value.info:eu-repo/semantics/publishedVersio

211007

This work will demonstrate a new flavor of the RA-TDMA set of protocols, namely RA-TDMAs+, which uses IEEE-802.11 (WiFi) COTS hardware in ad-hoc mode to set up a dynamic mesh network of mobile nodes with highbandwidth. The protocol uses topology tracking to configure the TDMA frame and robust relative synchronization to define the TDMA slots without resorting to a global clock and in the presence of interfering traffic. The demo will set up a small-scale testbed using COTS hardware, thus evidencing the feasibility of the approach, and it will show 1clive plots 1d of the temporal (synchronization) and topological views of the network.This work was partially supported by National Funds through FCT/MCTES (Portuguese Foundation for Science and Technology), within the CISTER Research Unit (UIDB/04234/2020); by the Operational Competitiveness Programme and Internationalization (COMPETE 2020) under the PT2020 Agreement, through the European Regional Development Fund (ERDF); also by FCT and the ESF (European Social Fund) through the Regional Operational Programme (ROP) Norte 2020, under PhD grant 2020.06685.BD; and within the AQUAMON project (PTDC/CCI-COM/30142/2017).info:eu-repo/semantics/publishedVersio

220604

This research proposes a novel minimal-overlap centrality-driven gateway designation method for real-time wireless sensor networks (WSNs). The goal is to enhance network schedulability by design, particularly, by exploiting the relationship between path node-overlaps and gateway designation. To this aim, we define a new metric termed minimal-overlap network centrality which characterizes the overall overlapping degree between all the active flows in the network when a given node is selected as gateway. The metric is then used to designate as gateway the node which produces the least overall number of path overlaps. For the purposes of evaluation, we assume a time-synchronized channel-hopping (TSCH) WSN under centralized earliest-deadline-first (EDF) scheduling and shortest-path routing. The assessment of the WSN traffic schedulability suggests our approach is dominant over classical network centrality metrics, namely, eigenvector, closeness, betweenness, and degree. Notably, it achieves up to 50% better schedulability than a degree centrality benchmark.This work was partially supported by National Funds through FCT/MCTES (Portuguese Foundation for Science and Technology), within the CISTER Research Unit (UIDB/04234/2020); by the Operational Competitiveness Programme and Internationalization (COMPETE 2020) under the PT2020 Agreement, through the European Regional Development Fund (ERDF); also by FCT and the ESF (European Social Fund) through the Regional Operational Programme (ROP) Norte 2020, under PhD grant 2020.06685.BDN/

A nature-inspired protocol to generate mature hiPSC-derived hepatocytes: Unveiling the role of human intestinal microbiome

The production of hepatocytes derived from human induced pluripotent stem cells (hiPSC-HLC) holds great promise for multiple cell therapies and tissue engineering applications. Nonetheless, the current protocols to generate HLC in vitro are not yet successfully established resulting in low yields of mainly immature cells when compared to the adult counterparts. The major hurdle in recapitulating in vitro the physiological liver maturation process is due to its complexity as it takes approximately 2 years after birth and involves a wide range of biological events (1). Recent findings have been suggesting that liver maturation, that naturally occur during the early postnatal period, can be strongly associated with human intestinal microbiome (2). For example, lithocholic acid and vitamin K2, two intestinal postbiotics, were shown to induce the expression of CYP450 enzymes in HLC and fetal hepatocytes (3). Additionally, studies on germ-free animals reported dissimilar xenobiotic enzyme profiles (4) and an impaired liver regeneration (5) compared to wild type animals. Considering these evidences, we developed a nature-inspired bioprocess to produce relevant numbers of highly functional and mature HLC for application in regenerative medicine. In this study, hiPSC-HLC were generated as 3D cell aggregates in stirred-tank bioreactors according to the integrated bioprocess developed previously by our group (6), and matured with a novel strategy based on human intestinal microbiota’s secretome. The maturation profile of hiPSC-HLC was evaluated at transcriptional and functional levels, and the composition of microbial secretome formulation was also characterized by UPLC-MS/MS, GC-MS and LC–MS/MS technologies. Our results showed an efficient hiPSC differentiation into hepatic lineage with a production of 2.8x106 HLC/mL (~370 million cells in a 200mL ST-BR), displaying a mixture of adult (~80%ALB+ cells) and fetal traits (~30%AFP+ cells and CYP3A7+ cells). Noteworthy, HLC treated with bacterial secretome showed higher ALB expression (87%ALB+ cells), ALB and A1AT secretion, urea synthesis, and basal and inducible CYP3A4 metabolism, when compared to untreated HLC that were cultured in standard hepatocyte maintenance medium. Detailed analytical characterization of the microbial secretome revealed some of the potential biologically active molecules, such as bile acids, short-chain fatty acids and vitamins that could be responsible for HLC in vitro maturation. In conclusion, the protocol developed herein presents high technological relevance due to its efficiency, scalability, and reproducibility, but also unveils the potential role of human intestinal microbiome in hepatic cell maturation. Noteworthy, we also demonstrated that the 3D aggregates of mature hiPSC-HLC were able to adhere and migrate in human hepatic extracellular matrix scaffolds, while maintained their viability and functional features, showing to hold great promise to be used as cell therapy products or as cell ingredients for liver bioengineering applications. This work was funded by Projects EHD16PI02 from CIBERehd and LMP226_18 funded by DGA (Spain) as well as by Fundação para a Ciência e Tecnologia (FCT)-funded projects ERAdicatPH (E-Rare3/0002/2015) and iNOVA4Health Research Unit (LISBOA-01-0145-FEDER-007344). J.I. A. and P.V. were supported by FCT fellowships SFRH/BD/116780/2016 and SFRH/BD/145767/2019, respectively. [1] Chen C, Soto-Gutierrez A, Baptista PM, Spee B. Biotechnology Challenges to In Vitro Maturation of Hepatic Stem Cells. Gastroenterology. 2018;154(5):1258–72; [2] Almeida, Joana I., Miguel F. Tenreiro, Lucía Martinez-Santamaria, Aspizua, Sara Guerrero, Javier P. Gisbert, Paula M. Alves, Margarida Serra PMB. Hallmarks of the human intestinal microbiome on liver maturation and function. J Hepatol. 2021; [3] Avior Y, Levy G, Zimerman M, Kitsberg D, Schwartz R, Sadeh R, et al. Microbial-Derived Lithocholic Acid and Vitamin K2 Drive the Metabolic Maturation of Pluripotent Stem Cells-Derived and Fetal Hepatocytes. Hepatology. 2015;62(1):265–78; [4] Selwyn FP, Cheng SL, Bammler TK, Prasad B, Vrana M, Klaassen C, et al. Developmental regulation of drug-processing genes in livers of germ-free mice. Toxicol Sci. 2015;147(1):84–103; [5] Cornell RP, Liljequist BL, Bartizal KF. Depressed liver regeneration after partial hepatectomy of germ‐free, athymic and lipopolysaccharide‐resistant mice. Hepatology. 1990;11(6):916–22; [6] Isidro, I., Vicente, P., Pais, D., Almeida, Joana I., Domingues, M., Abecasis, B., Mertinez-Turrillas, R., Rodriguez-Madoz, Juan R., Aspegren, A., Alves, Paula M., Serra M. On-line monitoring of hiPSC expansion and hepatic differentiation process in a 3D culture system by dielectric spectroscopy. Biotechnol Bioeng

A variational principle for actions on symmetric symplectic spaces

We present a definition of generating functions of canonical relations, which are real functions on symmetric symplectic spaces, discussing some conditions for the presence of caustics. We show how the actions compose by a neat geometrical formula and are connected to the hamiltonians via a geometrically simple variational principle which determines the classical trajectories, discussing the temporal evolution of such ``extended hamiltonians'' in terms of Hamilton-Jacobi-type equations. Simplest spaces are treated explicitly.Comment: 28 pages. Edited english translation of first author's PhD thesis (2000

230702

This article presents a novel centrality-driven gateway designation framework for the improved real-time performance of low-power wireless sensor networks (WSNs) at system design time. We target time-synchronized channel hopping (TSCH) WSNs with centralized network management and multiple gateways with the objective of enhancing traffic schedulability by design. To this aim, we propose a novel network centrality metric termed minimal-overlap centrality that characterizes the overall number of path overlaps between all the active flows in the network when a given node is selected as gateway. The metric is used as a gateway designation criterion to elect as a gateway the node leading to the minimal number of overlaps. The method is then extended to multiple gateways with the aid of the unsupervised learning method of spectral clustering. Concretely, after a given number of clusters are identified, we use the new metric at each cluster to designate as cluster gateway the node with the least overall number of overlaps. Extensive simulations with random topologies under centralized earliest-deadline-first (EDF) scheduling and shortest-path routing suggest our approach is dominant over traditional centrality metrics from social network analysis, namely, eigenvector, closeness, betweenness, and degree. Notably, our approach reduces by up to 40% the worst-case end-to-end deadline misses achieved by classical centrality-driven gateway designation methods.This work was partially supported by National Funds through FCT/MCTES (Portuguese Foundation for Science and Technology), within the CISTER Research Unit (UIDB/04234/2020); by the Operational Competitiveness Programme and Internationalization (COMPETE 2020) under the PT2020 Agreement, through the European Regional Development Fund (ERDF); also by FCT and the ESF (European Social Fund) through the Regional Operational Programme (ROP) Norte 2020, under PhD grant 2020.06685.BD.info:eu-repo/semantics/publishedVersio