Distinct styles of fluvial deposition in a Cambrian rift basin

Process-based and facies models to account for the origin of pre-vegetation (i.e. pre-Silurian) preserved fluvial sedimentary architectures remain poorly defined in terms of their ability to account for the nature of the fluvial conditions required to accumulate and preserve architectural elements in the absence of the stabilizing influence of vegetation. In pre-vegetation fluvial successions, the repeated reworking of bars and minor channels that resulted in the generation and preservation of broad, tabular, stacked sandstone-sheets has been previously regarded as the dominant sedimentary mechanism. This situation is closely analogous to modern-day poorly vegetated systems developed in arid climatic settings. However, this study demonstrates the widespread presence of substantially more complex stratigraphic architectures. The Guarda Velha Formation of Southern Brazil is a >500 m-thick synrift fluvial succession of Cambrian age that records the deposits and sedimentary architecture of three distinct fluvial successions: (i) an early rift-stage system characterized by coarse-grained channel elements indicative of a distributive pattern with flow transverse to the basin axis; and two coeval systems from the early- to climax-rift stages that represent (ii) an axially directed, trunk fluvial system characterized by large-scale amalgamated sandy braid-bar elements, and (iii) a distributive fluvial system characterized by multi-storey, sandy braided-channel elements that flowed transverse to the basin axis. Integration of facies and architectural-element analysis with regional stratigraphic basin analysis, palaeocurrent and pebble-provenance analysis demonstrates the mechanisms responsible for preserving the varied range of fluvial architectures present in this pre-vegetation, rift-basin setting. Identified major controls that influenced pre-vegetation fluvial sedimentary style include: (i) spatial and temporal variation in discharge regime; (ii) the varying sedimentological characteristics of distinct catchment areas; (iii) the role of tectonic basin configuration and its direct role in influencing palaeoflow direction and fluvial style, whereby both the axial and transverse fluvial systems undertook a distinctive response to syn-depositional movement on basin-bounding faults. Detailed architectural analyses of these deposits reveal significant variations in geometry, with characteristics considerably more complex than that of simple, laterally extensive, stacked sandstone-sheets predicted by most existing depositional models for pre-vegetation fluvial systems. These results suggest that the sheet-braided style actually encompasses a varied number of different pre-vegetation fluvial styles. Moreover, this study demonstrates that contemporaneous axial and transverse fluvial systems with distinctive architectural expressions can be preserved in the same overall tectonic and climatic setting

Wellbeing at Work before and during the SARS-COV-2 Pandemic: A Brazilian Nationwide Study among Dietitians

This study aimed to evaluate the perceptions of dietitians' wellbeing at work before and during the SARS-COV-2 pandemic in Brazil. This cross-sectional study was performed using a previously validated instrument to investigate the wellbeing of dietitians at work in Brazil. The questionnaire on the wellbeing of dietitians was composed of 25 items (with a 5-point scale), characteristics, and questions about the SARS-COV-2 period. The application was carried out with GoogleForms(R)tool from 26 May to 7 June 2020. The weblink to access the research was sent via email, messaging apps, and social networks. Volunteers were recruited nationwide with the help of the Brazilian Dietitians Councils, support groups, as well as media outreach to reach as many dietitians as possible. Volunteers received, along with the research link, the invitation to participate, as well as the consent form. A representative sample of 1359 dietitians from all the Brazilian regions answered the questionnaire-mostly female (92.5%), Catholic (52.9%), from 25 to 39 years old (58.4%), with a partner (63.8%), and with no children (58%). Most of the participants continue working during the pandemic period (83.8%), but they did not have SARS-COV-2 (96%), nor did their family members (80.7%). The wellbeing at work before SARS-COV-2 was 3.88 +/- 0.71, statistically different (p< 0.05) from during the pandemic, with the wellbeing of 3.71 +/- 0.78. Wellbeing at work was higher before the pandemic for all the analyzed variables. Analyzing variables separately before and during the pandemic, dietitians with partners, children and a Ph.D. presented higher scores for wellbeing at work. Professionals receiving more than five times the minimum wage have higher scores. During the pandemic, better wellbeing was observed for dietitians working remotely

Ecology and Geography of Plague Transmission Areas in Northeastern Brazil

Plague in Brazil is poorly known and now rarely seen, so studies of its ecology are difficult. We used ecological niche models of historical (1966-present) records of human plague cases across northeastern Brazil to assess hypotheses regarding environmental correlates of plague occurrences across the region. Results indicate that the apparently focal distribution of plague in northeastern Brazil is indeed discontinuous, and that the causes of the discontinuity are not necessarily only related to elevation—rather, a diversity of environmental dimensions correlate to presence of plague foci in the region. Perhaps most interesting is that suitable areas for plague show marked seasonal variation in photosynthetic mass, with peaks in April and May, suggesting links to particular land cover types. Next steps in this line of research will require more detailed and specific examination of reservoir ecology and natural history

Time-Fractional Optimal Control of Initial Value Problems on Time Scales

We investigate Optimal Control Problems (OCP) for fractional systems involving fractional-time derivatives on time scales. The fractional-time derivatives and integrals are considered, on time scales, in the Riemann--Liouville sense. By using the Banach fixed point theorem, sufficient conditions for existence and uniqueness of solution to initial value problems described by fractional order differential equations on time scales are known. Here we consider a fractional OCP with a performance index given as a delta-integral function of both state and control variables, with time evolving on an arbitrarily given time scale. Interpreting the Euler--Lagrange first order optimality condition with an adjoint problem, defined by means of right Riemann--Liouville fractional delta derivatives, we obtain an optimality system for the considered fractional OCP. For that, we first prove new fractional integration by parts formulas on time scales.Comment: This is a preprint of a paper accepted for publication as a book chapter with Springer International Publishing AG. Submitted 23/Jan/2019; revised 27-March-2019; accepted 12-April-2019. arXiv admin note: substantial text overlap with arXiv:1508.0075

Quantitative TEM imaging of the magnetostructural and phase transitions in FeRh thin film systems

Equi-atomic FeRh is a very interesting material as it undergoes a magnetostructural transition from an antiferromagnetic (AF) to a ferromagnetic (FM) phase between 75-105 °C. Its ability to present phase co-existence separated by domain walls (DWs) above room temperature provides immense potential for exploitation of their DW motion in spintronic devices. To be able to effectively control the DWs associated with AF/FM coexistence in FeRh thin films we must fully understand the magnetostructural transition and thermomagnetic behaviour of DWs at a localised scale. Here we present a transmission electron microscopy investigation of the transition in planar FeRh thin-film samples by combining differential phase contrast (DPC) magnetic imaging with in situ heating. We perform quantitative measurements from individual DWs as a function of temperature, showing that FeRh on NiAl exhibits thermomagnetic behaviour consistent with the transition from AF to FM. DPC imaging of an FeRh sample with HF-etched substrate reveals a state of AF/FM co-existence and shows the transition from AF to FM regions proceeds via nucleation of small vortex structures, which then grow by combining with newly nucleated vortex states into larger complex magnetic domains, until it is in a fully-FM state

Probing ultrafast carrier dynamics and nonlinear absorption and refraction in core-shell silicon nanowires

We investigate the relaxation dynamics of photogenerated carriers in silicon nanowires consisting of a crystalline core and a surrounding amorphous shell, using femtosecond time-resolved differential reflectivity and transmission spectroscopy at photon energies of 3.15 eV and 1.57 eV. The complex behavior of the differential transmission and reflectivity transients is the mixed contributions from the crystalline core and the amorphous silicon on the nanowire surface and the substrate where competing effects of state filling and photoinduced absorption govern the carrier dynamics. Faster relaxation rates are observed on increasing the photo-generated carrier density. Independent experimental results on crystalline silicon-on-sapphire help us in separating the contributions from the carrier dynamics in crystalline core and the amorphous regions in the nanowire samples. Further, single beam z-scan nonlinear transmission experiments at 1.57 eV in both open and close aperture configurations yield two-photon absorption coefficient \$beta$ (~3 cm/GW) and nonlinear refraction coefficient \$gamma$ (-2.5x10^-4 cm2/GW).Comment: 6 pages, 6 figure

Strong CD4 T cell responses to Zika virus antigens in a cohort of Dengue virus immune mothers of congenital Zika virus syndrome infants

Background: There is an urgent need to understand the complex relationship between cross-reactive anti-viral immunity, disease susceptibility, and severity in the face of differential exposure to related, circulating Flaviviruses. Co-exposure to Dengue virus and Zika virus in Brazil is a case in point. A devastating aspect of the 2015-2016 South American Zika outbreak was the dramatic increase in numbers of infants born with microcephaly to mothers exposed to Zika virus during pregnancy. It has been proposed that this is more likely to ensue from Zika infection in women lacking cross-protective Dengue immunity. In this case series we measure the prevalence of Dengue immunity in a cohort of mothers exposed to Zika virus during pregnancy in the 2015-2016 Zika outbreak that gave birth to an infant affected by microcephaly and explore their adaptive immunity to Zika virus. Results: Fifty women from Sergipe, Brazil who gave birth to infants with microcephaly following Zika virus exposure during the 2015-16 outbreak were tested for serological evidence of Dengue exposure and IFNγ ELISpot spot forming cell (SFC) response to Zika virus. The majority (46/50) demonstrated Dengue immunity. IFNγ ELISpot responses to Zika virus antigens showed the following hierarchy: Env>NS1>NS3>C protein. Twenty T cell epitopes from Zika virus Env were identified. Responses to Zika virus antigens Env and NS1 were polyfunctional with cells making IFNγ, TNFα, IL-4, IL-13, and IL-10. In contrast, responses to NS5 only produced the immune regulatory TGFβ1 cytokine. There were SFC responses against Zika virus Env (1-20) and variant peptide sequences from West Nile virus, Dengue virus 1-4 and Yellow Fever virus. Conclusion: Almost all the women in our study showed serological evidence of Dengue immunity, suggesting that microcephaly can occur in DENV immune mothers. T cell immunity to Zika virus showed a multifunctional response to the antigens Env and NS1 and immune regulatory responses to NS5 and C protein. Our data support an argument that different viral products may skew the antiviral response to a more pro or anti-inflammatory outcome, with an associated impact on immunopathogenesis