Search

There is convincing observational evidence for an increasing cosmic-raypositron-to-electron ratio at energies larger than $\sim 10$~GeV, at odds withexpectations from secondary positron production. The most recent AMS-02 dataexhibit an interesting spectral feature consisting of a bump at an energyaround $300$~GeV followed by a drop around $\sim 800$~GeV. A possibleexplanation to the most recent data is that the excess positron originates fromdecaying dark matter. Here, we show that models consisting of two dark matterparticle species contributing equally to the global cosmological dark matterdensity provide strikingly good fits to the data. The favored models, with abest-fit with $\chi^2/d.o.f \sim 0.5$ consist of a first species weighing$750$~GeV decaying with a lifetime $\tau_{\chi}\sim 10^{26}$~s to $\tau$ leptonpairs (or to a pair of vector bosons subsequently decaying to a $\tau$ paireach), and a second species with a mass around 2.3 TeV decaying to $\mu$ leptonpairs. We provide a few possible concrete realizations for this scenario.

Short-lived mediators are often used to describe dark matter interactions with Standard Model particles. When the dark matter mass is heavier than the mass of the mediator, it may self-annihilate into short-lived mediators, and in some cases this might be the dominant annihilation channel. This scenario is known as secluded dark matter. We use Fermi-LAT observations of dwarf spheroidal galaxies, H.E.S.S. data from the Galactic center, and Planck measurements of the Cosmic Microwave Background to constrain secluded dark matter. We explore the interplay between these experiments and we assess the impact of the mediator mass on our bounds, an often overlooked yet very important point. In particular, we exclude pair -annihilation cross-sections greater or on the order of σ v ∼ 4 × 10-27 cm3/s for dark matter masses around 10 GeV and greater or on the order of σ v ∼ × 10-25 cm3/s for dark matter masses around a TeV . Our findings supersede previous constraints which use Fermi-LAT data, and constitute the first limits on secluded dark sectors using the H.E.S.S. telescope. We also show that one can fit TeV gamma-ray observations from H.E.S.S. with secluded dark matter annihilations, with the mediator mass impacting the best-fit dark matter particle mass. Our findings indicate that any assessment of secluded dark sectors in the context of indirect detection significantly depends on the choice of the mediator mass.

We discuss the phenomenology of an MeV-scale Dirac fermion coupled to theStandard Model through a dark photon with kinetic mixing with theelectromagnetic field. We compute the dark matter relic density and explore theinterplay of direct detection and accelerator searches for dark photons. Weshow that precise measurements of the temperature and polarization powerspectra of the Cosmic Microwave Background Radiation lead to stringentconstraints, leaving a small window for the thermal production of this MeV darkmatter candidate. The forthcoming MeV gamma-ray telescope e-ASTROGAM will offerimportant and complementary opportunities to discover dark matter particleswith masses below 10 MeV. Lastly, we discuss how a late-time inflation episodeand freeze-in production could conspire to yield the correct relic densitywhile being consistent with existing and future constraints.

We use the model of utilitarian redundancy as a basis for research. This model provides predictions that have not been tested by other research. In this sense, we sought to investigate the stem bark extraction between preferred and less-preferred species by a rural community in Caatinga environment. In addition, we sought to explain local preferences to observe if preferred plants have a higher content of tannins than less-preferred species. For this, we selected seven preferred species and seven less-preferred species from information obtained from semistructured interviews applied to 49 informants. Three areas of vegetation around the community were also selected, in which individuals were tagged, and were measured the diameter at ground level (DGL) diameter at breast height (DBH), and measurements of available and extracted bark areas. Samples of bark of the species were also collected for the evaluation of tannin content, obtained by the method of radial diffusion. From the results, the preferred species showed a greater area of bark removed. However, the tannin content showed no significant differences between preferred and less-preferred plants. These results show there is a relationship between preference and use, but this preference is not related to the total tannins content. [ABSTRACT FROM AUTHOR]

There are several species of plants used by traditional communities in the Brazilian semiarid. An approach used in the search for natural substances that possess therapeutic value is ethnobotany or ethnopharmacology. Active substances that have phenolic groups in their structure have great pharmacological potential. To establish a quantitative relationship between the species popularly considered to be antimicrobial, antidiabetic, and antidiarrheal, the contents of tannins and flavonoids were determined. The plant selection was based on an ethnobotanical survey conducted in a community located in the municipality of Altinho, northeastern Brazil. For determination of tannin content was utilized the technique of radial diffusion, and for flavonoids, an assay based on the complexation of aluminum chloride. The group of plants with antimicrobial indications showed a higher content of tannins compared to the control groups. The results evidence suggests a possible relationship between these compounds and the observed activity. [ABSTRACT FROM AUTHOR]

There are several species of plants used by traditional communities in the Brazilian semiarid. An approach used in the search for natural substances that possess therapeutic value is ethnobotany or ethnopharmacology. Active substances that have phenolic groups in their structure have great pharmacological potential. To establish a quantitative relationship between the species popularly considered to be antimicrobial, antidiabetic, and antidiarrheal, the contents of tannins and flavonoids were determined. The plant selection was based on an ethnobotanical survey conducted in a community located in the municipality of Altinho, northeastern Brazil. For determination of tannin content was utilized the technique of radial diffusion, and for flavonoids, an assay based on the complexation of aluminum chloride. The group of plants with antimicrobial indications showed a higher content of tannins compared to the control groups. The results evidence suggests a possible relationship between these compounds and the observed activity.