Biofilms on Plastic Litter: Community Composition and Activity and the Effects on Ecosystem Processes

The rapid increase of plastic production and disposal has resulted in plastic pollution becoming a global problem. In aquatic ecosystems, plastic litter is a substrate for biofilms, but little research has simultaneously assessed the effects of plastic litter on biofilm activity, community composition, and ecosystem processes. Our objectives were to: (1) measure biofilm activity and community composition on plastic litter relative to a natural surface in an urban river and (2) assess the impact of microplastic pollution on ecosystem metabolism and N2 flux in an oligotrophic lake. For objective (1) we incubated three common plastics with distinct physical and chemical properties and wood at three sizes. Biofilm activity was similar among substrates, except respiration was greater on wood. Bacterial and algal richness and diversity were highest on foam and wood substrates compared to film and firm polyethylene. Bacterial biofilm community composition was distinct between wood and plastic substrates while the algal community was distinct on both foam and wood. Substrate size had no influence on either algal or bacterial community composition. Overall, results demonstrate polymer properties influence biofilm alpha and beta diversity, which may affect transport and distribution of plastic pollution and associated microbes, as well as biogeochemical processes in urban streams. For objective (2), we added microplastics to pelagic mesocosms at a range of concentrations. Ecosystem metabolism rates were low, as expected for an oligotrophic lake, and similar across microplastic treatments. N2 was undersaturated in all treatments and showed no differences by microplastic concentration. Our results suggested minimal impact of microplastic on ecosystem metabolism and N2 flux in an oligotrophic lake. These data will be combined with results from collaborators on the larger project that assessed the role of microplastics at other levels of organization, including water chemistry, plankton, and fish. This study provides valuable insights into the effects of substrate on biofilm characteristics, the ecological impacts of plastic pollution in urban rivers, and is a novel addition to the literature as an assessment of the impacts of microplastic pollution on ecosystem-scale processes through in situ microplastic addition

Should the teaching of biological evolution include the origin of life?

The development of mainstream research on the origin of life as an outcome of Darwinian evolution is discussed. It is argued that prebiotic evolution and the origin of life should not be excluded from the syllabus and should be part of classes on biological evolution, and that the transition from non-living to living matter is best understood when seen as part of evolutionary biology. The wide acceptance of evolutionary approaches to the study of the emergence of life in European and Latin American countries is discussed

Charles Darwin and the Origin of Life

When Charles Darwin published The Origin of Species 150 years ago he consciously avoided discussing the origin of life. However, analysis of some other texts written by Darwin, and of the correspondence he exchanged with friends and colleagues demonstrates that he took for granted the possibility of a natural emergence of the first life forms. As shown by notes from the pages he excised from his private notebooks, as early as 1837 Darwin was convinced that “the intimate relation of Life with laws of chemical combination, & the universality of latter render spontaneous generation not improbable”. Like many of his contemporaries, Darwin rejected the idea that putrefaction of preexisting organic compounds could lead to the appearance of organisms. Although he favored the possibility that life could appear by natural processes from simple inorganic compounds, his reluctance to discuss the issue resulted from his recognition that at the time it was possible to undertake the experimental study of the emergence of life

Violência física intra-familiar entre jovens mexicanos e egípcios

OBJECTIVE: To determine the prevalence of experiencing intra-familial violence among Mexican and Egyptian youth and to describe its associated risk factors. METHODS: Data from questionnaires applied to 12,862 Mexican and 5,662 Egyptian youth, aged 10 to 19, who attended public schools were analyzed. Biviarate and logistic regression analysis were used to determine the relationship between socio-demographics, the experience of intra-familial violence and violence perpetration. RESULTS: The prevalence of having experienced intra-familial violence was comparable across the Mexican and Egyptian populations (14% and 17%, respectively). In Mexico, young men were more likely to have experienced such violence (OR=2.36) than women, whereas in Egypt, young women were at slightly greater risk than young men (OR=1.25). Older age, male gender and urban residence were independent correlates of experiencing intra-familial violence among Mexican youth. For Egyptian adolescents, in contrast, younger age, female gender and having non-married parents were independent correlates of victimization. Intra-familial violence victims were also more likely than non-victims to perpetrate violence (Mexico: OR=13.13; Egypt: OR=6.58). CONCLUSIONS: Mexican and Egyptian youth experienced intra-familial violence at a relatively low prevalence when compared with youth of other countries. A strong association was found between experiencing intra-familial violence and perpetrating violence.OBJETIVO: Determinar a prevalência da violência intra-familiar sofrida por jovens mexicanos e egípcios, e descrever os fatores de risco associados. MÉTODOS: Os dados analisados foram obtidos de questionários aplicados a 12.862 mexicanos e 5.662 egípcios, jovens de 10 a 19 anos, que freqüentam escolas públicas. O relacionamento entre fatores sociodemográficos, a violência sofrida e sua perpetração foram investigados por meio de análise bivariada e regressão logística. RESULTADOS: A prevalência de violência intra-familiar foi comparável entre as populações mexicana e egípcia (14% e 17%, respectivamente). No México, essa violência foi muito mais provável entre os homens jovens do que entre mulheres (OR=2,36), enquanto que no Egito era mais provável entre as mulheres jovens do que homens (OR=1,25). Idade mais elevada, gênero masculino e residência urbana são fatores associados a violência intra-familiar entre jovens mexicanos. Entre jovens egípcios, a idade mais baixa,o gênero feminino e pais não casados foram fatores associados a essa violência. Foi mais provável a repetição da violência pelos jovens que eram vítimas da violência intra-familiar (México: OR=13,13; Egito: OR=6,58). CONCLUSÕES: A prevalência de experimentar a violência intra-familiar de jovens mexicanos e egípcios foi baixa em comparação com jovens em outros países. Houve forte associação entre vítimas de violência intra-familiar e a repetição da violência

Escribir papers bajo el régimen del management académico: Cuerpo, afectos y estrategias

Indexación: Scopus.Chile is a landmark case in opening up higher education to the free market and in the reformulation of the logics that regulate scientific production in universities. This translates into a management system for academic staff oriented by productivity bonuses associated with high-impact publications, by the distribution of research funds conditional on the productivity of researchers and by the rank of academic tasks. In this article, we present the results of a study that sought to explore and understand how highly productive social science academics describe scientific writing from everyday labor practice framed in new regulations of scientific production. Through the analysis of 20 interviews, we propose 3 categories: affectivity, fragility and strategy. These give an account of everyday aspects, as well as tensions and conflicts present in the process of scientific writing.https://atheneadigital.net/article/view/v20-1-fardela-carriel-lazcano-et-a

Natural History, Microbes and Sequences: Shouldn't We Look Back Again to Organisms?

The discussion on the existence of prokaryotic species is reviewed. The demonstration that several different mechanisms of genetic exchange and recombination exist has led some to a radical rejection of the possibility of bacterial species and, in general, the applicability of traditional classification categories to the prokaryotic domains. However, in spite of intense gene traffic, prokaryotic groups are not continuously variable but form discrete clusters of phenotypically coherent, well-defined, diagnosable groups of individual organisms. Molecularization of life sciences has led to biased approaches to the issue of the origins of biodiversity, which has resulted in the increasingly extended tendency to emphasize genes and sequences and not give proper attention to organismal biology. As argued here, molecular and organismal approaches that should be seen as complementary and not opposed views of biology

Determinants of Acceptance of Cervical Cancer Screening in Dar es Salaam, Tanzania.

To describe how demographic characteristics and knowledge of cervical cancer influence screening acceptance among women living in Dar es Salaam, Tanzania. Multistage cluster sampling was carried out in 45 randomly selected streets in Dar es Salaam. Women between the ages of 25-59 who lived in the sampled streets were invited to a cervical cancer screening; 804 women accepted and 313 rejected the invitation. Information on demographic characteristics and knowledge of cervical cancer were obtained through structured questionnaire interviews. Women aged 35-44 and women aged 45-59 had increased ORs of 3.52 and 7.09, respectively, for accepting screening. Increased accepting rates were also found among single women (OR 2.43) and among women who had attended primary or secondary school (ORs of 1.81 and 1.94). Women who had 0-2 children were also more prone to accept screening in comparison with women who had five or more children (OR 3.21). Finally, knowledge of cervical cancer and awareness of the existing screening program were also associated with increased acceptance rates (ORs of 5.90 and 4.20). There are identifiable subgroups where cervical cancer screening can be increased in Dar es Salaam. Special attention should be paid to women of low education and women of high parity. In addition, knowledge and awareness raising campaigns that goes hand in hand with culturally acceptable screening services will likely lead to an increased uptake of cervical cancer screening

Toward homochiral protocells in noncatalytic peptide systems

The activation-polymerization-epimerization-depolymerization (APED) model of Plasson et al. has recently been proposed as a mechanism for the evolution of homochirality on prebiotic Earth. The dynamics of the APED model in two-dimensional spatially-extended systems is investigated for various realistic reaction parameters. It is found that the APED system allows for the formation of isolated homochiral proto-domains surrounded by a racemate. A diffusive slowdown of the APED network such as induced through tidal motion or evaporating pools and lagoons leads to the stabilization of homochiral bounded structures as expected in the first self-assembled protocells.Comment: 10 pages, 5 figure