Three-dimensional Maxwellian extended Newtonian gravity and flat limit

In the present work we find novel Newtonian gravity models in three space-time dimensions. We first present a Maxwellian version of the extended Newtonian gravity, which is obtained as the non-relativistic limit of a particular U(1)-enlargement of an enhanced Maxwell Chern-Simons gravity. We show that the extended Newtonian gravity appears as a particular sub-case. Then, the introduction of a cosmological constant to the Maxwellian extended Newtonian theory is also explored. To this purpose, we consider the non-relativistic limit of an enlarged symmetry. An alternative method to obtain our results is presented by applying the semigroup expansion method to the enhanced Nappi-Witten algebra. The advantages of considering the Lie algebra expansion procedure is also discussed

Resorcinolic Lipids from Yucatecan Propolis

Propolis is a material produced by bees from a combination of plant exudates and wax, used to fill out cracks in the beehive and to defend against intruders and pathogenic microorganisms; it is recognized for its many biological activities and its chemical composition depends on the botanical sources close to the beehive. The objective of this investigation was to isolate and identify metabolites with antioxidant activity present in a propolis sample collected in Yucatan, Mexico. Purification of the bioactive metabolites was carried out using argentation chromatography, while the combination of 1H nuclear magnetic resonance (NMR), laser desorption ionization (LDI), gas chromatography-mass spectrometry (GC-MS) and biosynthetic origin data allowed their identification as resorcinolic lipids. Finally, the resin of Mangifera indica was identified as the botanical source of these metabolite

CRISP Spectropolarimetric Imaging of Penumbral Fine Structure

We discuss penumbral fine structure in a small part of a pore, observed with the CRISP imaging spectropolarimeter at the Swedish 1-m Solar Telescope (SST), close to its diffraction limit of 0.16 arcsec. Milne-Eddington inversions applied to these Stokes data reveal large variations of field strength and inclination angle over dark-cored penumbral intrusions and a dark-cored light bridge. The mid-outer part of this penumbra structure shows 0.3 arcsec wide spines, separated by 1.6 arcsec (1200 km) and associated with 30 deg inclination variations. Between these spines, there are no small-scale magnetic structures that easily can be be identified with individual flux tubes. A structure with nearly 10 deg more vertical and weaker magnetic field is seen midways between two spines. This structure is co-spatial with the brightest penumbral filament, possibly indicating the location of a convective upflow from below.Comment: Accepted for publication in ApJL 17 Oct 2008. One Figure adde

A population-based controlled experiment assessing the epidemiological impact of digital contact tracing

While Digital contact tracing (DCT) has been argued to be a valuable complement to manual tracing in the containment of COVID-19, no empirical evidence of its effectiveness is available to date. Here, we report the results of a 4-week population-based controlled experiment that took place in La Gomera (Canary Islands, Spain) between June and July 2020, where we assessed the epidemiological impact of the Spanish DCT app Radar Covid. After a substantial communication campaign, we estimate that at least 33% of the population adopted the technology and further showed relatively high adherence and compliance as well as a quick turnaround time. The app detects about 6.3 close-contacts per primary simulated infection, a significant percentage being contacts with strangers, although the spontaneous follow-up rate of these notified cases is low. Overall, these results provide experimental evidence of the potential usefulness of DCT during an epidemic outbreak in a real population

Beyond Eliashberg superconductivity in MgB2: anharmonicity, two-phonon scattering, and multiple gaps

Density-functional calculations of the phonon spectrum and electron-phonon coupling in MgB$_2$ are presented. The $E_{2g}$ phonons, which involve in-plane B displacements, couple strongly to the $p_{x,y}$ electronic bands. The isotropic electron-phonon coupling constant is calculated to be about 0.8. Allowing for different order parameters in different bands, the superconducting $\lambda$ in the clean limit is calculated to be significantly larger. The $E_{2g}$ phonons are strongly anharmonic, and the non-linear contribution to the coupling between the $E_{2g}$ modes and the p$_{x,y}$ bands is significant.Comment: 4 pages, 3 figure

Effect of diacutaneous fibrolysis on the muscular properties of gastrocnemius muscle

Diacutaneous fibrolysis is a noninvasive technique that has been shown to be effective in the treatment of musculoskeletal disorders such as shoulder pain, lateral epicondylalgia, patellofemoral pain syndrome and carpal tunnel syndrome. However, while diacutaneous fibrolysis is applied to soft tissue, its effects on muscular properties are unknown. The purpose of the present study was to evaluate the effects of diacutaneous fibrolysis on muscle properties as measured by tensiomyography and myotonometry in asymptomatic subjects. An analytical descriptive study was performed. A single session of diacutaneous fibrolysis on the gastrocnemius muscle was applied to one limb (treated limb group) and the other limb was the control (control limb group). Subjects were assessed with tensiomyography and myotonometry before treatment (T0), after treatment (T1) and 30 minutes later (T2). The primary outcomes were tensiomyography and myotonometry variables. The treated limb group showed a statistically significant increase (p<0.05) in tensiomyography parameters. A decrease in rigidity and increase in relaxation was also observed on myotonometry at T1, with some of the effects being maintained at T2. Rigidity and relaxation at T1 were statistically significant between groups (p<0.05). A single session of diacutaneous fibrolysis to the gastrocnemius muscle of asymptomatic subjects produced immediate changes in muscle properties. These changes were maintained 30 minutes after the application of the technique

The Molecular Interstellar Medium of the Local Group Dwarf NGC6822

Do molecular clouds collapse to form stars at the same rate in all environments? In large spiral galaxies, the rate of transformation of H2 into stars (hereafter SFE) varies little. However, the SFE in distant objects (z~1) is much higher than in the large spiral disks that dominate the local universe. Some small local group galaxies share at least some of the characteristics of intermediate-redshift objects, such as size or color. Recent work has suggested that the Star Formation Efficiency (SFE, defined as the SFRate per unit H2) in local Dwarf galaxies may be as high as in the distant objects. A fundamental difficulty in these studies is the independent measure of the H2 mass in metal-deficient environments. At 490 kpc, NGC6822 is an excellent choice for this study; it has been mapped in the CO(2-1) line using the multibeam receiver HERA on the 30 meter IRAM telescope, yielding the largest sample of giant molecular clouds (GMCs) in this galaxy. Despite the much lower metallicity, we find no clear difference in the properties of the GMCs in NGC 6822 and those in the Milky Way except lower CO luminosities for a given mass. Several independent methods indicate that the total H2 mass in NGC 6822 is about 5 x 10^6 Msun in the area we mapped and less than 10^7 Msun in the whole galaxy. This corresponds to a NH2/ICO ~ 4 x 10^{21} cm^-2 /(Kkm/s) over large scales, such as would be observed in distant objects, and half that in individual GMCs. No evidence was found for H2 without CO emission. Our simulations of the radiative transfer in clouds are entirely compatible with these NH2/ICO values. The SFE implied is a factor 5 - 10 higher than what is observed in large local universe spirals.Comment: 16 pages, 13 figures. Accepted for publication in Astronomy and Astrophysic

The role of extracellular matrix on liver stem cell fate: A dynamic relationship in health and disease

The liver stem cell niche is a specialized and dynamic microenvironment with biomechanical and biochemical characteristics that regulate stem cell behavior. This is feasible due to the coordination of a complex network of secreted factors, small molecules, neural, blood inputs and extracellular matrix (ECM) components involved in the regulation of stem cell fate (self-renewal, survival, and differentiation into more mature phenotypes like hepatocytes and cholangiocytes). In this review, we describe and summarize all the major components that play essential roles in the liver stem cell niche, in particular, growth factor signaling and the biomechanical properties of the ECM