6,527 research outputs found
Effective Sublattice Magnetization and Neel Temperature in Quantum Antiferromagnets
We present an analytic expression for the finite temperature effective
sublattice magnetization which would be detected by inelastic neutron
scattering experiments performed on a two-dimensional square-lattice quantum
Heisenberg antiferromagnets with short range N\'eel order. Our expression,
which has no adjustable parameters, is able to reproduce both the qualitative
behaviour of the phase diagram and the experimental values of the
N\'eel temperature for either doped YBaCuO and
stoichiometric LaCuO compounds. Finally, we remark that by
incorporating frustration and 3D effects as perturbations is sufficient to
explain the deviation of the experimental data from our theoretical curves.Comment: 4 pages, RevTex, 3 figure
Pulsar Timing Sensitivities to Gravitational Waves from Relativistic Metric Theories of Gravity
Pulsar timing experiments aimed at the detection of gravitational radiation
have been performed for decades now. With the forthcoming construction of large
arrays capable of tracking multiple millisecond pulsars, it is very likely we
will be able to make the first detection of gravitational radiation in the
nano-Hertz band, and test Einstein's theory of relativity by measuring the
polarization components of the detected signals. Since a gravitational wave
predicted by the most general relativistic metric theory of gravity accounts
for {\it six} polarization modes (the usual two Einstein's tensor polarizations
as well as two vector and two scalar wave components), we have estimated the
single-antenna sensitivities to these six polarizations. We find pulsar timing
experiments to be significantly more sensitive, over their entire observational
frequency band ( Hz), to scalar-longitudinal and
vector waves than to scalar-transverse and tensor waves. At Hz and
with pulsars at a distance of kpc, for instance, we estimate an average
sensitivity to scalar-longitudinal waves that is more than two orders of
magnitude better than the sensitivity to tensor waves. Our results imply that a
direct detection of gravitational radiation by pulsar timing will result into a
test of the theory of general relativity that is more stringent than that based
on monitoring the decay of the orbital period of a binary system.Comment: 11 pages, 2 figures. Submitted to Phys. Rev.
The Systemic Imprint of Growth and Its Uses in Ecological (Meta)Genomics
Microbial minimal generation times range from a few minutes to several weeks. They are evolutionarily determined by variables such as environment stability, nutrient availability, and community diversity. Selection for fast growth adaptively imprints genomes, resulting in gene amplification, adapted chromosomal organization, and biased codon usage. We found that these growth-related traits in 214 species of bacteria and archaea are highly correlated, suggesting they all result from growth optimization. While modeling their association with maximal growth rates in view of synthetic biology applications, we observed that codon usage biases are better correlates of growth rates than any other trait, including rRNA copy number. Systematic deviations to our model reveal two distinct evolutionary processes. First, genome organization shows more evolutionary inertia than growth rates. This results in over-representation of growth-related traits in fast degrading genomes. Second, selection for these traits depends on optimal growth temperature: for similar generation times purifying selection is stronger in psychrophiles, intermediate in mesophiles, and lower in thermophiles. Using this information, we created a predictor of maximal growth rate adapted to small genome fragments. We applied it to three metagenomic environmental samples to show that a transiently rich environment, as the human gut, selects for fast-growers, that a toxic environment, as the acid mine biofilm, selects for low growth rates, whereas a diverse environment, like the soil, shows all ranges of growth rates. We also demonstrate that microbial colonizers of babies gut grow faster than stabilized human adults gut communities. In conclusion, we show that one can predict maximal growth rates from sequence data alone, and we propose that such information can be used to facilitate the manipulation of generation times. Our predictor allows inferring growth rates in the vast majority of uncultivable prokaryotes and paves the way to the understanding of community dynamics from metagenomic data
Cooper pairing and superconductivity in a spin fluctuation model for high-Tc cuprate superconductors
Menthol-based deep eutectic systems as antimicrobial and anti-inflammatory agents for wound healing
Funding Information: This work received funding from Foundation for Science and Technology (FCT) , through project PTDC/BBB- 490 EBB/1676/2014 – Des.Zyme and ERC-2016-CoG 725034 (ERC Consolidator Grant Des.solve). E.S. and J.S. would also like to acknowledge the financial support by the Portuguese Foundation for Science and Technology (FCT) through the doctoral grant with reference number SFRH/BD/143902/2019 and postdoctoral contract CEECIND/01026/2018 , respectively. Publisher Copyright: © 2022Effective antimicrobial treatment has been identified as a serious and unmet medical need. Herein, we present a strategy based on deep eutectic systems (DES) to overcome current limitations, answering the need not only to effectively kill bacterial agents but also to avoid their adhesion and proliferation, which is associated with biofilm formation and have a crucial impact on bacterial virulence. To achieve such a goal, natural deep eutectic systems (NADES) based on menthol (Me) and saturated free fatty acids (FFA) were produced, fully physicochemical characterized, and its bioactive properties were described. The antimicrobial potential of menthol-based NADES with FFA, namely, myristic acid (MA), lauric acid (LA), and stearic acid (SA) were investigated towards a broad panel of microorganisms. The obtained data indicates that NADES possess effective antimicrobial properties towards the Gram-positive bacterial and fungal strains tested. Among the tested formulations, Me:LA at a molar ratio of 4:1 molar was used to carry out a biofilm detachment/removal assay due to is superior microbiological properties. This formulation was able to effectively lead to biofilm removal/dispersion of not only methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans, but also Escherichia coli, without the need of any additional physical force or antibiotic. Furthermore, since microbial invasion and biofilm formation is highly undesired in wound healing, namely in chronic wound healing, the wound healing properties of these eutectic formulations was also investigated. The results suggest that these NADES can cope with microbial invasion and biofilm detachment while not compromising normal keratinocyte proliferation and migration verified in wound healing and epidermis repair, while also contributing to the reduction of cell stress and inflammation via the control of ROS production. In conclusion, these results provide the indication that NADES based on Me and FFA holds great interest as antimicrobial agents for preventive and therapeutic applications in various clinical settings, including wound healing.publishersversionpublishe
- …