421 research outputs found
Amalgamated products and properly 3-realizable groups
In this paper, we show that the class of all properly 3-realizable groups is
closed under amalgamated free products (and HNN-extensions) over finite groups.
We recall that is said to be properly 3-realizable if there exists a
compact 2-polyhedron with and whose universal cover
has the proper homotopy type of a 3-manifold (with boundary).Comment: J. Pure Appl. Alg., to appea
Elevated immune gene expression is associated with poor reproductive success of urban blue tits
Urban and forest habitats differ in many aspects that can lead to modifications of the immune system of wild animals. Altered parasite communities, pollution, and artificial light at night in cities have been associated with exacerbated inflammatory responses, with possibly negative fitness consequences, but few data are available from free-living animals. Here, we investigate how urbanization affects major immune pathways and experimentally test potentially contributing factors in blue tits (Cyanistes caeruleus) from an urban and forest site. We first compared breeding adults by quantifying the mRNA transcript levels of proteins associated with anti-bacterial, anti-malarial (TLR4, LY86) and anti-helminthic (Type 2 transcription factor GATA3) immune responses. Adult urban and forest blue tits differed in gene expression, with significantly increased TLR4 and GATA3, but not LY86, in the city. We then experimentally tested whether these differences were environmentally induced by cross-fostering eggs between the sites and measuring mRNA transcripts in nestlings. The populations differed in reduced reproductive success, with a lower fledging success and lower fledgling weight recorded at the urban site. This mirrors the findings of our twin study reporting that the urban site was severely resource limited when compared to the forest. Because of low urban survival, robust gene expression data were only obtained from nestlings reared in the forest. Transcript levels in these nestlings showed no (TLR4, LY86), or weak (GATA3), differences according to their origin from forest or city nests, suggesting little genetic or maternal contribution to nestling immune transcript levels. Lastly, to investigate differences in parasite pressure between urban and forest sites, we measured the prevalence of malaria in adult and nestling blood. Prevalence was invariably high across environments and not associated with the transcript levels of the studied immune genes. Our results support the hypothesis that inflammatory pathways are activated in an urban environment and suggest that these differences are most likely induced by environmental factors
Weak -structures and one-relator groups
Motivated by the notion of boundary for hyperbolic and groups, M.
Bestvina in "Local Homology Properties of Boundaries of Groups" introduced the
notion of a (weak) -structure and (weak) -boundary for
a group of type (i.e., having a finite complex), with
implications concerning the Novikov conjecture for . Since then, some
classes of groups have been shown to admit a weak -structure (see
"Weak -structures for some classes of groups" by C.R. Guilbault for
example), but the question whether or not every group of type
admits such a structure remains open. In this paper, we show that every torsion
free one-relator group admits a weak -structure, by showing that
they are all properly aspherical at infinity; moreover, in the -ended case
the corresponding weak -boundary has the shape of either a circle
or a Hawaiian earring depending on whether the group is a virtually surface
group or not. Finally, we extend this result to a wider class of groups still
satisfying a Freiheitssatz property
Optimising piezoelectric and magnetoelectric responses on CoFe2O4/P(VDF-TrFE) nanocomposites
Magnetoelectric nanocomposite films composed of magnetostrictive CoFe2O4 nanoparticles
with sizes between 35 and 55 nm embedded in P(VDF-TrFE) have been successfully prepared
by a solvent casting method. The ferroelectric, piezoelectric, magnetic and magnetoelectric
properties of the nanocomposite and their variation with the wt% of the ferrite filler, thickness
of the composite and direction of the applied magnetic field have been investigated.
Ferroelectric and piezoelectric properties are improved when small amount of ferrite
nanoparticles were added to the polymeric matrix. Magnetic properties vary linearity with
ferrite content. The highest magnetoelectric response of 41.3 mV/cmOe was found in the
composite with 72wt% when a 2.5 kOe DC field was transversely applied to the sample surface.
This value is among the highest reported in two phase particulate polymer nanocomposites.
Thickness of the composite has no influence in the magnetoelectric response, allowing tailoring
sensor thickness for specific applications. The good value of the magnetoelectric coefficient and
the flexibility of the films make these composites suitable for applications in magnetoelectric
smart devices.Fundação para a Ciência e a Tecnologia (FCT)
(PTDC/CTM/69316/2006), (SFRH/BD/45265/2008).FEDER “Programa Operacional Factores de Competitividade – COMPETE” (NANO/NMed-SD/0156/2007)Basque Government Industry Department - Project Actimat (ETORTEK-IE10-272)COST Action MP1003, 2010 - The „European Scientific Network for Artificial Muscles‟ (ESNAM)
The Compact Linear ee Collider (CLIC): Accelerator and Detector
The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear
ee collider under development by international collaborations hosted by
CERN. This document provides an overview of the design, technology, and
implementation aspects of the CLIC accelerator and the detector. For an optimal
exploitation of its physics potential, CLIC is foreseen to be built and
operated in stages, at centre-of-mass energies of 380 GeV, 1.5 TeV and 3 TeV,
for a site length ranging between 11 km and 50 km. CLIC uses a two-beam
acceleration scheme, in which normal-conducting high-gradient 12 GHz
accelerating structures are powered via a high-current drive beam. For the
first stage, an alternative with X-band klystron powering is also considered.
CLIC accelerator optimisation, technical developments, and system tests have
resulted in significant progress in recent years. Moreover, this has led to an
increased energy efficiency and reduced power consumption of around 170 MW for
the 380 GeV stage, together with a reduced cost estimate of approximately 6
billion CHF. The detector concept, which matches the physics performance
requirements and the CLIC experimental conditions, has been refined using
improved software tools for simulation and reconstruction. Significant progress
has been made on detector technology developments for the tracking and
calorimetry systems. The construction of the first CLIC energy stage could
start as early as 2026 and first beams would be available by 2035, marking the
beginning of a physics programme spanning 25-30 years and providing excellent
sensitivity to Beyond Standard Model physics, through direct searches and via a
broad set of precision measurements of Standard Model processes, particularly
in the Higgs and top-quark sectors.Comment: Input to the European Particle Physics Strategy Update on behalf of
the CLIC and CLICdp Collaboration
Prevalence of anxiety in the COVID-19 pandemic: An updated meta-analysis of community-based studies
Background: The unprecedented worldwide crisis caused by the rapid spread of COVID-19 and the restrictive public health measures enforced by some countries to slow down its transmission have severely threatened the physical and mental wellbeing of communities globally.
Methods: We conducted a systematic review and meta-analysis to determine the prevalence of anxiety in the general population during the COVID-19 pandemic. Two researchers independently searched for cross-sectional community-based studies published between December 1, 2019 and August 23, 2020, using PubMed, WoS, Embase, and other sources (e.g., grey literature, manual search).
Results: Of 3049 records retrieved, 43 studies were included. These studies yielded an estimated overall prevalence of anxiety of 25%, which varied significantly across the different tools used to measure anxiety. Consistently reported risk factors for the development of anxiety included initial or peak phase of the outbreak, female sex, younger age, marriage, social isolation, unemployment and student status, financial hardship, low educational level, insufficient knowledge of COVID-19, epidemiological or clinical risk of disease and some lifestyle and personality variables.
Conclusions: As the overall global prevalence of anxiety disorders is estimated to be 7.3% normally, our results suggest that rates of anxiety in the general population could be more than 3 times higher during the COVID-19 pandemic. These findings suggest a substantial impact on mental health that should be targeted by individual and population-level strategies
Squalene through its post-squalene metabolites is a modulator of hepatic transcriptome in rabbits
Squalene is a natural bioactive triterpene and an important intermediate in the biosynthesis of sterols. To assess the effect of this compound on the hepatic transcriptome, RNA-sequencing was carried out in two groups of male New Zealand rabbits fed either a diet enriched with 1% sunflower oil or the same diet with 0.5% squalene for 4 weeks. Hepatic lipids, lipid droplet area, squalene, and sterols were also monitored. The Squalene administration downregulated 9 transcripts and upregulated 13 transcripts. The gene ontology of transcripts fitted into the following main categories: transporter of proteins and sterols, lipid metabolism, lipogenesis, anti-inflammatory and anti-cancer properties. When the results were confirmed by RT-qPCR, rabbits receiving squalene displayed significant hepatic expression changes of LOC100344884 (PNPLA3), GCK, TFCP2L1, ASCL1, ACSS2, OST4, FAM91A1, MYH6, LRRC39, LOC108176846, GLT1D1 and TREH. A squalene-enriched diet increased hepatic levels of squalene, lanosterol, dihydrolanosterol, lathosterol, zymostenol and desmosterol. Strong correlations were found among specific sterols and some squalene-changed transcripts. Incubation of the murine AML12 hepatic cell line in the presence of lanosterol, dihydrolanosterol, zymostenol and desmosterol reproduced the observed changes in the expressions of Acss2, Fam91a1 and Pnpla3. In conclusion, these findings indicate that the squalene and post-squalene metabolites play important roles in hepatic transcriptional changes required to protect the liver against malfunction. © 2022 by the authors. Licensee MDPI, Basel, Switzerland
Estudio en estructuras de hormigón armado Velocidad de ultrasonidos y resistencia a compresión
So far, much of the research conducted to estimate the compressive strength of reinforced concrete elements of our structures have been made based on checkups witness many samples drawn from these elements.
By this investigation 185 real cases of reinforced concrete structural elements are studied by a structural check based on the correlation of results between the ultrasonic velocity (V) and compressive strength (R). The study was developed taking into account the location of the building relative to the shoreline and the age of the structure. Subsequently, a statistical analysis to the data obtained is performed. This work has achieved a scientific method of analysis of the two test methods and necessary for a full structural check, correlation between them and most innovativeprocess, making mathematical formulas and graphs mapping tools which demonstrate the effectiveness of the procedure, which is proposed as a contribution to policy.Hasta ahora, gran parte de las investigaciones llevadas a cabo para la estimación de las resistencias a compresión de los elementos de hormigón armado de nuestras estructuras, se han realizado en base a chequeos con gran número de probetas testigo, extraídas de esos elementos.Mediante la presente investigación se estudian 185 casos reales de elementos estructurales de hormigón armado, mediante un chequeo estructural basado en la correlación de resultados entre la Velocidad de Ultrasonidos (V) y la Resistencia a Compresión (R). El estudio se desarrolla teniendo en cuenta localización de la construcción respecto a la costa marina y la edad de la propia estructura. Posteriormente se realiza un análisis estadístico con los datos obtenidos con este trabajo se ha conseguido un claro procedimiento científico de análisis de los dos métodos de ensayo y de las herramientas necesarias para realizar un completo chequeo estructural, correlación entre ellos y lo más novedoso del proceso, la confección de fórmulas matemáticas y las gráficas de correlación, que ponen de manifiesto la efectividad del procedimiento, que se propone como aportación para normativa. 
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