Non-extensive entropy from incomplete knowledge of Shannon entropy?

In this paper we give an interpretation of Tsallis' nonextensive statistical mechanics based upon the information-theoretic point of view of Luzzi et al. [cond-mat/0306217; cond-mat/0306247; cond-mat/0307325], suggesting Tsallis' entropy to be not a fundamental concept but rather a derived one, stemming from an incomplete knowledge of the system, not taking properly into account its interaction with the environment. This interpretation seems to avoid some problems occurring with the original interpretation of Tsallis statistics.Comment: v.4. 11 pages. Title changed. Content substantially changed: added discussion of several points raised by various referees and readers; Also reference made to work by Luzzi, Vasconcellos, Galvao Ramos. Physica Scripta, to appea

An analysis of referrals to a level 3 intensive care unit in a resource-limited setting in South Africa

Background. With a shortage of intensive care unit (ICU) beds and rising healthcare costs in resource-limited settings, clinicians need to appropriately triage admissions into ICU to avoid wasteful expenditure and unnecessary bed utilisation. Objective. To assess the nature, appropriateness and outcome of referrals to a tertiary centre ICU. Methods. A retrospective review of ICU consults from September 2016 to February 2017 at King Edward VIII Hospital was performed. The study was approved by the University of KwaZulu-Natal Biomedical Research Ethics Committee (BE291/17). Data pertaining to patients’ demographics, referring doctor, diagnosis, comorbidities as well as biochemical and haemodynamic parameters were extracted. This information was then cross- referenced to the outcome of the ICU consultation. Data were descriptively analysed. Results. Five hundred consultations were reviewed over a 6-month period; 52.2% of patients were male and the mean age was 44 years. Junior medical officers referred 164 (32.8%) of the consultations. Although specialist supervision was available in 459 cases, it was only utilised in 339 (73.9%) of these cases. Most referrals were from tertiary (46.8%) or regional (30.4%) hospitals; however, direct referrals from district hospitals and clinics accounted for 20.4% and 1.4% of consultations, respectively. The appropriate referral pathway was not followed in 81 (16.2%) consultations. Forty-five percent of consults were accepted; however, 9.3% of these patients died before arrival in ICU. A total of 151 (30.2%) patients were refused ICU admission, with the majority (57%) of these owing to futility. Patients were unstable at the time of consult in 53.2% of referrals and 34.4% of consults had missing data. Conclusion. Critically ill patients are often referred by junior doctors without senior consultation, and directly from low-level healthcare facilities. A large proportion of ICU referrals are deemed futile and, of the patients accepted for admission, almost 1 in 10 dies prior to ICU admission. More emphasis needs to be placed on the training of doctors to appropriately triage and manage critically ill patients and ensure appropriate ICU referral and optimising of patient outcomes

Stability and Antioxidant Activity of Semi-synthetic Derivatives of 4-Nerolidylcatechol.

4-nerolidylcatechol (4-NC) is an unstable natural product that exhibits important antioxidant, anti-inflammatory and other properties. It is readily obtainable on a multi-gram scale through straightforward solvent extraction of the roots of cultivated Piper peltatum or P. umbellatum, followed by column chromatography on the resulting extract. Semi-synthetic derivatives of 4-NC with one or two substituent groups (methyl, acetyl, benzyl, benzoyl) on the O atoms have been introduced that have increased stability compared to 4-NC and significant in vitro inhibitory activity against the human malaria parasite Plasmodium falciparum. Antioxidant and anti-inflammatory properties may be important for the antiplasmodial mode of action of 4-NC derivatives. Thus, we decided to investigate the antioxidant properties, cytotoxicity and stability of 4-NC derivatives as a means to explore the potential utility of these compounds. 4-NC showed high antioxidant activity in the DPPH and ABTS assays and in 3T3-L1 cells (mouse embryonic fibroblast), however 4-NC was more cytotoxic (IC50 = 31.4 µM) and more unstable than its derivatives and lost more than 80% of its antioxidant activity upon storage in solution at −20 °C for 30 days. DMSO solutions of mono-O-substituted derivatives of 4-NC exhibited antioxidant activity and radical scavenging activity in the DPPH and ABTS assays that was comparable to that of BHA and BHT. In the cell-based antioxidant model, most DMSO solutions of derivatives of 4-NC were less active on day 1 than 4-NC, quercetin and BHA and more active antioxidants than BHT. After storage for 30 days at −20 °C, DMSO solutions of most of the derivatives of 4-NC were more stable and exhibited more antioxidant activity than 4-NC, quercetin and BHA and exhibited comparable antioxidant activity to BHT. These findings point to the potential of derivatives of 4-NC as antioxidant compounds

The Critical Care Society of Southern Africa guidelines on the allocation of scarce critical care resources during the COVID-19 public health emergency in South Africa

Letter by Gopalan et al. on article by Singh and Moodley (Singh JA, Moodley K. Critical care triaging in the shadow of COVID-19: Ethics considerations. S Afr Med J 2020;110(5):355-359. https://doi.org/10.7196/SAMJ.2020.v110i5.14778); and response by Singh and Moodle

The challenges of ethical research with children

As especificidades da pesquisa com crianças têm ganhado visibilidade nas produções acadêmicas em diversas áreas de conhecimento, com destaque para a Sociologia da Infância, principalmente a partir dos “novos estudos sobre a infância” os quais emergiram ao final da década de 1980. Essa visibilidade acontece devida a questões como: a discussão sobre as imagens da infância, construídas socio-historicamente; o reconhecimento da condição das crianças enquanto atores sociais, portanto, seres competentes, que atribuem significações a suas experiências e contextos; e o reconhecimento das crianças enquanto sujeitos de direitos, reconhecimento este pautado pela Doutrina da Proteção Integral. Permeadas por essas questões, as pesquisas com crianças agregam a questão da Ética nas atividades desenvolvidas na relação pesquisador-criança. No contexto dessa discussão, este trabalho propõe refletir sobre essas questões e os cuidados éticos nesse tipo de pesquisa, considerando a condição da criança enquanto sujeito de direitos. Foi realizado um recorte da produção acadêmica representativa na área da Sociologia da Infância nas duas últimas décadas, identificando quais aspectos aparecem nas preocupações dos autores, quais abordagens norteiam a discussão desses aspectos e, principalmente, que concepção de infância está presente nessa produção.The specificities of research with children have gained visibility in scientific publications in various areas of knowledge, especially in Sociology of Childhood and the “new studies of childhood”, which emerged at the end of the 1980s. This fact is due to discussions about childhood from a socio-historical perspective; the recognition of children as social actors and therefore able to give meaning to their experiences and contexts; and the recognition of children as individuals entitled to rights, according to the Doutrina da Proteção Integral (Full Protection Doctrine). Therefore, research ethics is an essential element of good research governance, especially in terms of activities related to the relationship between the researcher and child. Accordingly, the objective of this study is to examine and explore these issues, considering the child as an individual entitled to rights. A literature review of articles published in the last two decades in the area of Sociology of Childhood was conducted to identify the main issues and topics addressed, the approaches that guided the discussions and, especially, to identify the conception of childhood present in these studies.CIEC - Centro de Investigação em Estudos da Criança, IE, UMinho (UI 317 da FCT), Portuga

Nycthemeral and Monthly Occupation of the Fish Assemblage on a Sheltered Beach of Baía Norte, Florianópolis, Santa Catarina State, Brazil

Interpreting fish community records is challenging for several reasons, including the lack of past ichthyofauna data, the cyclical temporal variations in the community, and the methodology employed, which usually underestimates fish assemblages. The objective of this study was to describe short-scale and meso-scale (nycthemeral period and months, respectively) temporal variations in the ichthyofauna composition and structure of a sheltered beach of Baía Norte (Florianópolis, Santa Catarina state, Brazil), using a capéchade net. Samples were collected monthly for a period of 48 hours. During the period from December 2010 to November 2011, a total of 19,302 individuals belonging to 89 species and 39 families were captured. The number of individuals that were sampled during the day and/or night was dependent on the sampling month. On average, the daytime assemblage was more abundant and different in structure and composition than the nighttime assemblage. Of the eight species that had the highest Index of Relative Importance (%IRI), five had higher variations (ANOVA F) between the day and night than between the months. This finding reinforced the need for sampling during both the day and night. The capéchade net effectively captured demersal and pelagic individuals in a broad range of sizes