Trapping of Spin-0 fields on tube-like topological defects

We have considered the localization of resonant bosonic states described by a scalar field $\Phi$ trapped in tube-like topological defects. The tubes are formed by radial symmetric defects in $(2,1)$ dimensions, constructed with two scalar fields $\phi$ and $\chi$, and embedded in the $(3,1)-$dimensional Minkowski spacetime. The general coupling between the topological defect and the scalar field $\Phi$ is given by the potential $\eta F(\phi,\chi)\Phi^2$. After a convenient decomposition of the field $\Phi$, we find that the amplitudes of the radial modes satisfy Schr\"odinger-like equations whose eigenvalues are the masses of the bosonic resonances. Specifically, we have analyzed two simple couplings: the first one is $F(\phi,\chi)=\chi^2$ for a fourth-order potential and, the second one is a sixth-order interaction characterized by $F(\phi,\chi)=(\phi\chi)^2$% . In both cases the Schr\"odinger-like equations are numerically solved with appropriated boundary conditions. Several resonance peaks for both models are obtained and the numerical analysis showed that the fourth-order potential generates more resonances than the sixth-order one.Comment: 7 pages, 10 figures, matches version published in Physics Letters

Suppression of two-bounce windows in kink-antikink collisions

We consider a class of topological defects in $(1,1)$-dimensions with a deformed $\phi^4$ kink structure whose stability analysis leads to a Schr\"odinger-like equation with a zero-mode and at least one vibrational (shape) mode. We are interested in the dynamics of kink-antikink collisions, focusing on the structure of two-bounce windows. For small deformation and for one or two vibrational modes, the observed two-bounce windows are explained by the standard mechanism of a resonant effect between the first vibrational and the translational modes. With the increasing of the deformation, the effect of the appearance of more than one vibrational mode is the gradual disappearance of the initial two-bounce windows. The total suppression of two-bounce windows even with the presence of a vibrational mode offers a counterexample from what expected from the standard mechanism. For even larger deformation, some two-bounce windows reappear, but with a non-standard structure.Comment: 13 pages, 6 figure

SARS-CoV-2 decreases malaria severity in co-infected rodent models

Coronavirus disease 2019 (COVID-19) and malaria, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Plasmodium parasites, respectively, share geographical distribution in regions where the latter disease is endemic, leading to the emergence of co-infections between the two pathogens. Thus far, epidemiologic studies and case reports have yielded insufficient data on the reciprocal impact of the two pathogens on either infection and related diseases. We established novel co-infection models to address this issue experimentally, employing either human angiotensin-converting enzyme 2 (hACE2)-expressing or wild-type mice, in combination with human- or mouse-infective variants of SARS-CoV-2, and the P. berghei rodent malaria parasite. We now show that a primary infection by a viral variant that causes a severe disease phenotype partially impairs a subsequent liver infection by the malaria parasite. Additionally, exposure to an attenuated viral variant modulates subsequent immune responses and provides protection from severe malaria-associated outcomes when a blood stage P. berghei infection was established. Our findings unveil a hitherto unknown host-mediated virus-parasite interaction that could have relevant implications for disease management and control in malaria-endemic regions. This work may contribute to the development of other models of concomitant infection between Plasmodium and respiratory viruses, expediting further research on co-infections that lead to complex disease presentations.info:eu-repo/semantics/publishedVersio

Kink scattering in the presence of geometric constrictions

We investigate kink-antikink collisions in a model characterized by two scalar fields in the presence of geometric constrictions. The model includes an auxiliary function that modifies the kinematics associated with one of the two fields. An important fact is that one of the fields can be solved independently, being responsible for changing the internal structure of the second one. We performed several collisions and observed the presence of resonance windows for small values of the parameters. Furthermore, we have been able to show the alternation between the appearance of oscillating pulses, as well as the annihilation and formation of kink-antikink pairs when the geometric constriction is more pronounced. The study of kink dynamics in models with geometric constrictions is connected with issues of interest such as domain wall formation and magnetization at the manometric scale.Comment: 30 pages, 17 figures, final version to be published in JHE

Ornithogenic soil toposequence on Rata island, Fernando de Noronha archipelago, south atlantic and quaternary paleoclimatic implications.

The formation of highly phosphatized soils on sites of avian activity is a common feature of oceanic islands. We characterized a toposequence of phosphatic soils on Rata Island, to evaluate the soil genesis based on local topographic variations. For this purpose, four soils ranging from the upper hill down to the lowest landscape position on the island, representing a range of parent materials (basalt and calcareous sands), were analyzed. In the lowest landscape position a shallow Entisol was identified, strongly influenced by birds and marine sprays (Litholic Neosol), developed on " karstified" Pleistocene calcarenites; the three other soils in the upper part of the toposequence are Ornithogenic Inceptsols (Cambisols), ranging from a deep Cambisol profile on Basalt lava to intermediate Cambisols on mixed colluvial sediments of the basalt/calcareous. The lowermost Litholic Neosol is associated with a rugged landscape with strong calcarenite dissolution and karstification, related to a former wetter climate. The soil phosphatization is clearly an inherited process of the Late Quaternary age, when climate conditions were different. Initial weathering took place in the last interglacial period, under wetter conditions during which the Tertiary basalts were strongly weathered, leaving corestones in a saprolitic, oxidized mass. In the late Pleistocene, a gentle surface distributed these weathering products along the pediment slopes as colluvial materials, whereas in the coastal areas aeolian processes formed large sand dunes composed of reworked calcareous sands from marine sources during a time of very low sea level. During this time, widespread bird activity accounted for secondary apatite formation on the surface of calcareous oolites. Finally, the Holocene warming was accompanied by increasing sea level, enhanced tropical weathering, Fe and Al mobility and variscite formation superimposed on degraded Ca-phosphates, forming two phase phosphatic aggregates

Factors Influencing Marksmanship in Police Officers: A Narrative Review

Law enforcement officers routinely face unpredictable scenarios that may threaten the public, their colleagues, or themselves. In such situations, officers may be required to use firearms, with shooting accuracy becoming crucial. This literature review aimed to identify, synthesize, and report on research investigating factors that affect marksmanship in law enforcement personnel. A systematic search of seven databases was undertaken following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) approach. From an initial 5396 identified studies, 23 met the eligibility criteria. The key findings from these papers were: (1) physical exertion does not appear to decrease shooting performance, especially at close range (<10 m); (2) tactical load carriage does not appear to decrease shooting performance; in fact, it has been reported by officers as improving performance (likely due to training specificity); (3) the physical capability of officers may be of importance, notably grip strength, which the volume of evidence suggests is positively correlated with marksmanship; (4) anxiety imparted through high-stress scenarios negatively impacts shooting performance, but training under stress may counteract this factor, albeit for a short period. Together, these factors appear to have a trainability component where increased specific and realistic training can improve shooting accuracy, time, and precision, especially in high-stress situations

False vacuum decay in kink scattering

In this work we consider kink-antikink and antikink-kink collisions in a modified $\phi^4$ model with a false vacuum characterized by a dimensionless parameter $\epsilon$. The usual $\phi^4$ model is recovered for $\epsilon=0$. We investigate the $\epsilon<<1$ regime where the kink in the presence of false vacuum can be understood as a small deformation of the standard kink for the $\phi^4$ model. We show that the attractive interaction between the kink-antikink pair leads to a rich scattering pattern, in some cases delaying considerably the false vacuum decay.Comment: 16 pages, 17 figure