3,181 research outputs found
An Adaptive Observer-Based Controller Design for Active Damping of a DC Network with a Constant Power Load
© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis article explores a nonlinear, adaptive controller aimed at increasing the stability margin of a direct-current (dc), small-scale, electrical network containing an unknown constant power load (CPL). Due to its negative incremental impedance, this load reduces the effective damping of the network, which may lead to voltage oscillations and even to voltage collapse. To overcome this drawback, we consider the incorporation of a controlled dc-dc power converter in parallel with the CPL. The design of the control law for the converter is particularly challenging due to the existence of unmeasured states and unknown parameters. We propose a standard input-output linearization stage, to which a suitably tailored adaptive observer is added. The good performance of the controller is validated through experiments on a small-scale network.Peer ReviewedPostprint (author's final draft
Challenges for future food systems: from the Green Revolution to food supply chains with a special focus on sustainability
Finding a food system to feed the growing worldwide population remains a challenge, especially in the current era, where natural resources are being dramatically depleted. From a historical point of view, the Green Revolution, together with biofortification and sustainable intensification, was established as a possible solution to counter hunger and malnutrition during the second half of the 20th century. As a solution, to overcome the limitations attributed to the Green Revolution, food supply chains were developed. The current food system, based on the long food supply chain (LFSC), is characterized by globalization, promoting several advantages for both producers and consumers. However, LFSC has been demonstrated to be unable to feed the global population and, furthermore, it generates negative ecological, environmental, logistical, and nutritional pressures. Thus, novel efficient food systems are required to respond to current environmental and consumers' demands, as is the case of short food supply chain (SFSC). As a recently emerging food system, the evaluation of SFSC sustainability in terms of environmental, economic, and social assessment is yet to be determined. This review is focused on the evolution of food supply systems, starting from the Green Revolution to food supply chains, providing a significant perspective on sustainability.The research leading to these results was supported by MICINN supporting
the Ramón y Cajal grant for M. A. Prieto (RYC-2017-22891),
the Juan de la Cierva Incorporación for Hui Cao (IJC2020-04605-
5-I) and the FPU grant for A. Soria-Lopez (FPU2020/06140); by
Xunta de Galicia for supporting the program (EXCELENCIA-ED431F
2020/12) and by supporting the postdoctoral grant of M. Fraga-
Corral (ED481B-2019-096) and the predoctoral grants of M. Carpena
(ED481A 2021/313) and of P. Garcia-Oliveira (ED481A-2019/295);
and by the European Union through the “NextGenerationEU” program
supporting the “Margarita Salas” grant awarded to P. Garcia-Perez. The authors are grateful to Ibero-American Program on Science and
Technology (CYTED—AQUA-CIBUS, P317RT0003), to the Bio Based
Industries Joint Undertaking (JU) under grant agreement No. 888003
UP4HEALTH Project (H2020-BBI-JTI-2019) that supports the work of
P. Otero and P. Garcia-Perez. The JU receives support from the European
Union’s Horizon 2020 research and innovation program and the
Bio Based Industries Consortium. The project SYSTEMIC Knowledge
hub on Nutrition and Food Security, has received funding from national
research funding parties in Belgium (FWO), France (INRA), Germany
(BLE), Italy (MIPAAF), Latvia (IZM), Norway (RCN), Portugal (FCT), and
Spain (AEI) in a joint action of JPI HDHL, JPI-OCEANS and FACCE-JPI
launched in 2019 under the ERA-NET ERA-HDHL (No. 696295)
Benefits and drawbacks of ultrasound-assisted extraction for the recovery of bioactive compounds from marine algae
The increase in life expectancy has led to the appearance of chronic diseases and interest in
healthy aging, in turn promoting a growing interest in bioactive compounds (BCs) and functional
ingredients. There are certain foods or products rich in functional ingredients, and algae are one of
them. Algae consumption has been nominal in Europe until now. However, in recent years, it has
grown significantly, partly due to globalization and the adoption of new food trends. With the aim of
obtaining BCs from foods, multiple methods have been proposed, ranging from conventional ones,
such as maceration or Soxhlet extraction, to more innovative methods, e.g., ultrasound-assisted extraction
(UAE). UAE constitutes a novel method, belonging to so-called green chemistry, that enables
the extraction of BCs requiring lower amounts of solvent and energy costs, preserving the integrity
of such molecules. In recent years, this method has been often used for the extraction of different BCs
from a wide range of algae, especially polysaccharides, such as carrageenans and alginate; pigments,
including fucoxanthin, chlorophylls, or -carotene; and phenolic compounds, among others. In this
way, the application of UAE to marine algae is an efficient and sustainable strategy to pursue their
deep characterization as a new source of BCs, especially suitable for vegetarian and vegan diets.The research leading to these results was supported by MICINN supporting
the Ramón y Cajal grant for M.A. Prieto (RYC-2017-22891) and the FPU grant for A. Carreira-Casais
(FPU2016/06135); by Xunta de Galicia for supporting the pre-doctoral grants of P. Garcia-Oliveira
(ED481A-2019/295) and A.G. Pereira (ED481A-2019/0228); by University of Vigo for supporting
the predoctoral grant of M. Carpena (Uvigo-00VI 131H 6410211) and by Becas de Fundación ONCE
Programme “Oportunidad al Talento” that supports the work of A. Soria-Lopez.info:eu-repo/semantics/publishedVersio
A novel PKC activating molecule promotes neuroblast differentiation and delivery of newborn neurons in brain injuries
Neural stem cells are activated within neurogenic niches in response to brain injuries. This results in the production of neuroblasts, which unsuccessfully attempt to migrate toward the damaged tissue. Injuries constitute a gliogenic/non-neurogenic niche generated by the presence of anti-neurogenic signals, which impair neuronal differentiation and migration. Kinases of the protein kinase C (PKC) family mediate the release of growth factors that participate in different steps of the neurogenic process, particularly, novel PKC isozymes facilitate the release of the neurogenic growth factor neuregulin. We have demonstrated herein that a plant derived diterpene, (EOF2; CAS number 2230806-06-9), with the capacity to activate PKC facilitates the release of neuregulin 1, and promotes neuroblasts differentiation and survival in cultures of subventricular zone (SVZ) isolated cells in a novel PKC dependent manner. Local infusion of this compound in mechanical cortical injuries induces neuroblast enrichment within the perilesional area, and noninvasive intranasal administration of EOF2 promotes migration of neuroblasts from the SVZ towards the injury, allowing their survival and differentiation into mature neurons, being some of them cholinergic and GABAergic. Our results elucidate the mechanism of EOF2 promoting neurogenesis in injuries and highlight the role of novel PKC isozymes as targets in brain injury regeneration
Rickettsia slovaca Infection: DEBONEL/TIBOLA
Producción CientíficaThis study describes the epidemiological, clinical, and microbiological characteristics of a new tick-borne disease in Spain—Dermacentor-borne necrosis erythema lymphadenopathy (DEBONEL). The clinical presentations include an eschar at the site of the tick bite, surrounded by an erythema and painful regional lymphadenopathy. The disease appears during the colder months and its vector is Dermacentor marginatus (D. marginatus). From January 1990 to December 2004, 54 patients presented at Hospital of La Rioja with these clinical and epidemiological data. The ratio of females to males was 32/22. The average age was 37 years. In all cases tick bites were located on the upper body (90% on the scalp). The median incubation period was 4.7 days. Signs and symptoms were mild in all cases. Only a small number of patients presented mild and nonspecific abnormalities in a complete blood cell count and mild elevation of erythrocyte sedimentation rates and C-protein reactive and liver enzyme levels. Serological evidence of acute rickettsiosis was observed in 19 patients (61%). In 29% sera tested by polymerase chain reactions (PCRs) were positive. The sequence obtained from a PCR product revealed 98% identity with Rickettsia sp. strains RpA4, DnS14, and DnS28. All ticks removed from patients were PCR-positive. Sequencing showed 8 of them identified as R. slovaca and 2 as Rickettsia sp. strains RpA4, DnS14, and DnS28
Overcoming I/O bottleneck in superconducting quantum computing: multiplexed qubit control with ultra-low-power, base-temperature cryo-CMOS multiplexer
Large-scale superconducting quantum computing systems entail high-fidelity
control and readout of large numbers of qubits at millikelvin temperatures,
resulting in a massive input-output bottleneck. Cryo-electronics, based on
complementary metal-oxide-semiconductor (CMOS) technology, may offer a scalable
and versatile solution to overcome this bottleneck. However, detrimental
effects due to cross-coupling between the electronic and thermal noise
generated during cryo-electronics operation and the qubits need to be avoided.
Here we present an ultra-low power radio-frequency (RF) multiplexing
cryo-electronics solution operating below 15 mK that allows for control and
interfacing of superconducting qubits with minimal cross-coupling. We benchmark
its performance by interfacing it with a superconducting qubit and observe that
the qubit's relaxation times () are unaffected, while the coherence times
() are only minimally affected in both static and dynamic operation. Using
the multiplexer, single qubit gate fidelities above 99.9%, i.e., well above the
threshold for surface-code based quantum error-correction, can be achieved with
appropriate thermal filtering. In addition, we demonstrate the capability of
time-division-multiplexed qubit control by dynamically windowing calibrated
qubit control pulses. Our results show that cryo-CMOS multiplexers could be
used to significantly reduce the wiring resources for large-scale qubit device
characterization, large-scale quantum processor control and quantum error
correction protocols.Comment: 16+6 pages, 4+1+5 figures, 1 tabl
Differences in expression rather than methylation at placenta-specific imprinted loci is associated with intrauterine growth restriction
Background: genome-wide studies have begun to link subtle variations in both allelic DNA methylation and parent-of-origin genetic effects with early development. Numerous reports have highlighted that the placenta plays a critical role in coordinating fetal growth, with many key functions regulated by genomic imprinting. With the recent description of wide-spread polymorphic placenta-specific imprinting, the molecular mechanisms leading to this curious polymorphic epigenetic phenomenon is unknown, as is their involvement in pregnancies complications. Results: profiling of 35 ubiquitous and 112 placenta-specific imprinted differentially methylated regions (DMRs) using high-density methylation arrays and pyrosequencing revealed isolated aberrant methylation at ubiquitous DMRs as well as abundant hypomethylation at placenta-specific DMRs. Analysis of the underlying chromatin state revealed that the polymorphic nature is not only evident at the level of allelic methylation, but DMRs can also adopt an unusual epigenetic signature where the underlying histones are biallelically enrichment of H3K4 methylation, a modification normally mutually exclusive with DNA methylation. Quantitative expression analysis in placenta identified two genes, GPR1-AS1 and ZDBF2, that were differentially expressed between IUGRs and control samples after adjusting for clinical factors, revealing coordinated deregulation at the chromosome 2q33 imprinted locus. Conclusions: DNA methylation is less stable at placenta-specific imprinted DMRs compared to ubiquitous DMRs and contributes to privileged state of the placenta epigenome. IUGR-associated expression differences were identified for several imprinted transcripts independent of allelic methylation. Further work is required to determine if these differences are the cause IUGR or reflect unique adaption by the placenta to developmental stresses
Spatial Heterogeneity of Autoinducer Regulation Systems
Autoinducer signals enable coordinated behaviour of bacterial populations, a phenomenon originally described as quorum sensing. Autoinducer systems are often controlled by environmental substances as nutrients or secondary metabolites (signals) from neighbouring organisms. In cell aggregates and biofilms gradients of signals and environmental substances emerge. Mathematical modelling is used to analyse the functioning of the system. We find that the autoinducer regulation network generates spatially heterogeneous behaviour, up to a kind of multicellularity-like division of work, especially under nutrient-controlled conditions. A hybrid push/pull concept is proposed to explain the ecological function. The analysis allows to explain hitherto seemingly contradicting experimental findings
The ANTARES Optical Beacon System
ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It
consists of a three dimensional array of photomultiplier tubes that can detect
the Cherenkov light induced by charged particles produced in the interactions
of neutrinos with the surrounding medium. High angular resolution can be
achieved, in particular when a muon is produced, provided that the Cherenkov
photons are detected with sufficient timing precision. Considerations of the
intrinsic time uncertainties stemming from the transit time spread in the
photomultiplier tubes and the mechanism of transmission of light in sea water
lead to the conclusion that a relative time accuracy of the order of 0.5 ns is
desirable. Accordingly, different time calibration systems have been developed
for the ANTARES telescope. In this article, a system based on Optical Beacons,
a set of external and well-controlled pulsed light sources located throughout
the detector, is described. This calibration system takes into account the
optical properties of sea water, which is used as the detection volume of the
ANTARES telescope. The design, tests, construction and first results of the two
types of beacons, LED and laser-based, are presented.Comment: 21 pages, 18 figures, submitted to Nucl. Instr. and Meth. Phys. Res.
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