Equilibrium hydrostatic equation and Newtonian limit of the singular f(R) gravity

We derive the equilibrium hydrostatic equation of a spherical star for any gravitational Lagrangian density of the form $L=\sqrt{-g}f(R)$. The Palatini variational principle for the Helmholtz Lagrangian in the Einstein gauge is used to obtain the field equations in this gauge. The equilibrium hydrostatic equation is obtained and is used to study the Newtonian limit for $f(R)=R-\frac{a^{2}}{3R}$. The same procedure is carried out for the more generally case $f(R)=R-\frac{1}{n+2}\frac{a^{n+1}}{R^{n}}$ giving a good Newtonian limit.Comment: Revised version, to appear in Classical and Quantum Gravity

Locational preferences and spatial arrangement in the barrow landscape of Serra do Barbanza (North-western Iberia)

As anywhere else around the world, GIS is an essential tool in Galician Archaeology (NW Spain) when examining and analysing spatial data. This is also true for the study of mounds in that area, since spatial analysis and statistics have become increasingly used for contrasting hypotheses regarding the locational preferences of these monuments, usually inferred from observations made during fieldwork or taken from studies conducted elsewhere. Drawing on this basis, in this paper, we have analysed the locational patterns of the tumuli of the upper tracts of the Serra do Barbanza (Galicia, NW Spain). Using a site-predictive modelling approach, several environmental covariates were analysed in order to explore their potential role in explaining the distribution of prehistoric mounds in the area. Subsequently, we studied the clustering of these monuments via second-order modelling. Our results suggest that tumuli in the Serra do Barbanza tended to cluster on a very local scale, a trend that can only be explained by intended site spacing strategies that may have taken place over millennia. Finally, by using significance testing via Monte Carlo Simulation, we have modelled both the effect of possible preferences regarding the location of mounds and the potential impact of tradition, with pre-existent megaliths possibly fostering the construction of more monuments in the nearby areas

A System to Generate SignWriting for Video Tracks Enhancing Accessibility of Deaf People

Video content has increased much on the Internet during last years. In spite of the efforts of different organizations and governments to increase the accessibility of websites, most multimedia content on the Internet is not accessible. This paper describes a system that contributes to make multimedia content more accessible on the Web, by automatically translating subtitles in oral language to SignWriting, a way of writing Sign Language. This system extends the functionality of a general web platform that can provide accessible web content for different needs. This platform has a core component that automatically converts any web page to a web page compliant with level AA of WAI guidelines. Around this core component, different adapters complete the conversion according to the needs of specific users. One adapter is the Deaf People Accessibility Adapter, which provides accessible web content for the Deaf, based on SignWritting. Functionality of this adapter has been extended with the video subtitle translator system. A first prototype of this system has been tested through different methods including usability and accessibility tests and results show that this tool can enhance the accessibility of video content available on the Web for Deaf people

Comparing scalar-tensor gravity and f(R)-gravity in the Newtonian limit

Recently, a strong debate has been pursued about the Newtonian limit (i.e. small velocity and weak field) of fourth order gravity models. According to some authors, the Newtonian limit of $f(R)$-gravity is equivalent to the one of Brans-Dicke gravity with $\omega_{BD} = 0$, so that the PPN parameters of these models turn out to be ill defined. In this paper, we carefully discuss this point considering that fourth order gravity models are dynamically equivalent to the O'Hanlon Lagrangian. This is a special case of scalar-tensor gravity characterized only by self-interaction potential and that, in the Newtonian limit, this implies a non-standard behavior that cannot be compared with the usual PPN limit of General Relativity. The result turns out to be completely different from the one of Brans-Dicke theory and in particular suggests that it is misleading to consider the PPN parameters of this theory with $\omega_{BD} = 0$ in order to characterize the homologous quantities of $f(R)$-gravity. Finally the solutions at Newtonian level, obtained in the Jordan frame for a $f(R)$-gravity, reinterpreted as a scalar-tensor theory, are linked to those in the Einstein frame.Comment: 9 page

Amino-acid-based surfactants: New antimicrobial agents

The rapid increase of drug resistant bacteria makes necessary the development of new antimicrobial agents. Synthetic amino acid-based surfactants constitute a promising alternative to conventional antimicrobial compounds given that they can be prepared from renewable raw materials. In this review, we discuss the structural features that promote antimicrobial activity of amino acid-based surfactants. Monocatenary, dicatenary and gemini surfactants that contain different amino acids on the polar head and show activity against bacteria are revised. The synthesis and basic physico-chemical properties have also been included

Clinical Implications of Epigenetic Dysregulation in Perinatal Hypoxic-Ischemic Brain Damage

Placental and fetal hypoxia caused by perinatal hypoxic-ischemic events are major causes of stillbirth, neonatal morbidity, and long-term neurological sequelae among surviving neonates. Brain hypoxia and associated pathological processes such as excitotoxicity, apoptosis, necrosis, and inflammation, are associated with lasting disruptions in epigenetic control of gene expression contributing to neurological dysfunction. Recent studies have pointed to DNA (de)methylation, histone modifications, and non-coding RNAs as crucial components of hypoxic-ischemic encephalopathy (HIE). The understanding of epigenetic dysregulation in HIE is essential in the development of new clinical interventions for perinatal HIE. Here, we summarize our current understanding of epigenetic mechanisms underlying the molecular pathology of HI brain damage and its clinical implications in terms of new diagnostic, prognostic, and therapeutic tools.Fil: Bustelo, Martí. Universidad de Buenos Aires; Argentina. Maastricht University Medical Center; Países Bajos. Universidad Católica de Cuyo - Sede San Juan; ArgentinaFil: Barkhuizen, Melinda. Maastricht University Medical Center; Países BajosFil: van den Hove, Daniel L. A.. Universiteit Maastricht.; Países BajosFil: Steinbusch, Harry Wilhelm. M.. Universiteit Maastricht.; Países BajosFil: Bruno, Martin. Universidad Católica de Cuyo - Sede San Juan; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Loidl, Cesar Fabian. Universidad Catolica de Cuyo - Sede San Luis; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Gavilanes, Antonio W. Danilo. Maastricht University Medical Cente; Países Bajo

Using zebrafish embryo bioassays combined with high-resolution mass spectrometry screening to assess ecotoxicological water bodies quality status: A case study in Panama rivers

Several studies show that many water bodies in developing countries are increasingly affected by anthropogenic pressure, such as agricultural activities, domestic and industrial wastewater. However, data is scarce in several of such countries, including Panama. Thus, in this work, the ecotoxicological status of selected rivers in Panama with distinct input sources were evaluated using the zebrafish (Danio rerio) embryo bioassays combined with a liquid chromatography-high resolution mass spectrometry screening of contaminants of emerging concern (CECs), using a library of over 3200 chemicals. A total of 68 CECs, including pharmaceuticals and metabolites, pesticides and several industrial chemicals, could be tentatively identified. Additionally, the zebrafish embryo bioassays showed a significant increase (p < 0.05) in embryo mortality/abnormalities when incubated with water samples from two rivers, Matasnillo and Curundú (47.5% and 32%, respectively). Importantly, a positive correlation between ecotoxicological endpoints and some of the detected CECs was observed. The findings demonstrate that both rivers are under strong anthropogenic pressure, and therefore, management actions are urgently needed to decrease their level of contamination. Overall, this study further supports the use of the zebrafish embryo bioassay as a fast, high throughput approach for screening the toxicity of water samples, and highlights the advantages of combining ecotoxicological assays with high-resolution mass spectrometry to an expedite assessment of the ecotoxicological status of water bodies.This work was supported by the Portuguese Foundation for Science and Technology (FCT) (PTDC|CTA-AMB|31554|2017; UIDB/04423/2020; UIDP/04423/2020), the Spanish Agencia Estatal de Investigación (ref. CTM2017-84763-C3-2-R), the Galician Council of Culture, Education and Universities (ref. ED431C2017/36 and Verónica Castro predoctoral contract, ref. ED481A-2017/156), co-funded by the European Regional Development Fund (ERDF/FEDER).2023-02-02S

New cationic vesicles prepared with double chain surfactants from arginine: role of the hydrophobic group on the antimicrobial activity and cytotoxicity

Cationic double chain surfactants have attracted much interest because they can give rise to cationic vesicles that can be used in biomedical applications. Using a simple and economical synthetic approach, we have synthesized four double-chain surfactants with different alkyl chain lengths (LANHCx). The critical aggregation concentration of the double chain surfactants is at least one order of magnitude lower than the CMC of their corresponding single-chain LAM and the solutions prepared with the LANHCx contain stable cationic vesicles. Encouragingly, these new arginine derivatives show very low haemolytic activity and weaker cytotoxic effects than conventional dialkyl dimethyl ammonium surfactants. In addition, the surfactant with the shortest alkyl chain exhibits good antimicrobial activity against Gram-positive bacteria. The results show that a rational design applied to cationic double chain surfactants might serve as a promising strategy for the development of safe cationic vesicular systems

Vav proteins are key regulators of Card9 signaling for innate antifungal immunity

Fungal infections are major causes of morbidity and mortality, especially in immunocompromised individuals. The innate immune system senses fungal pathogens through Syk-coupled C-type lectin receptors (CLRs), which signal through the conserved immune adaptor Card9. Although Card9 is essential for antifungal defense, the mechanisms that couple CLR-proximal events to Card9 control are not well defined. Here, we identify Vav proteins as key activators of the Card9 pathway. Vav1, Vav2, and Vav3 cooperate downstream of Dectin-1, Dectin-2, and Mincle to engage Card9 for NF-κB control and proinflammatory gene transcription. Although Vav family members show functional redundancy, Vav1/2/3(-/-) mice phenocopy Card9(-/-) animals with extreme susceptibility to fungi. In this context, Vav3 is the single most important Vav in mice, and a polymorphism in human VAV3 is associated with susceptibility to candidemia in patients. Our results reveal a molecular mechanism for CLR-mediated Card9 regulation that controls innate immunity to fungal infections