Concurrent Kleene Algebra: Free Model and Completeness

Concurrent Kleene Algebra (CKA) was introduced by Hoare, Moeller, Struth and Wehrman in 2009 as a framework to reason about concurrent programs. We prove that the axioms for CKA with bounded parallelism are complete for the semantics proposed in the original paper; consequently, these semantics are the free model for this fragment. This result settles a conjecture of Hoare and collaborators. Moreover, the techniques developed along the way are reusable; in particular, they allow us to establish pomset automata as an operational model for CKA.Comment: Version 2 includes an overview section that outlines the completeness proof, as well as some extra discussion of the interpolation lemma. It also includes better typography and a number of minor fixes. Version 3 incorporates the changes by comments from the anonymous referees at ESOP. Among other things, these include a worked example of computing the syntactic closure by han

The distribution of estuarine fish larvae: nutritional condition and co-occurrence with predators and prey

Fish larvae were collected monthly between March and September 1997 in the Mira and Guadiana estuaries (southern Portugal). Hydrological parameters were registered and zooplankton samples were obtained simultaneously. Densities of fish larvae (ind.100 m(-3)) were calculated from 211 samples and larval nutritional condition measured as RNA/DNA ratios were obtained for 346 individuals, using a fluorimetric method for nucleic acid quantification. Correlating variables were further studied using multiple regression analysis in order to assess the relative importance of abiotic and biotic factors affecting within-year trends in abundance and nutritional condition of estuarine fish larvae. Results indicated that: 1) the abundance of fish larvae seems conditioned by temperature and predation; and 2) their nutritional condition is dependent on temperature and prey availability. Temperature is an important variable structuring estuaries and therefore conditions the behaviour and physiology of fish larvae. Furthermore, the co-occurrence of predators and larvae might be related to similar feeding patterns or comensalism. Whenever feeding conditions are suitable, they usually determine enhanced growth and nutritional condition. However, predation seems to control this latter relationship through its effect on larval mortality. (C) 2000 Editions scientifiques et Medicales Elsevier SAS.info:eu-repo/semantics/publishedVersio

Co-creating obesity prevention policies with youth: Policy ideas generated through the CO-CREATE project

Despite growing recognition of the importance of applying a systems lens to action on obesity, there has only been limited analysis of the extent to which this lens has actually been applied. The CO-CREATE project used a youth-led participatory action research approach to generate policy ideas towards the reduction of adolescent overweight and obesity across Europe. In order to assess the extent to which these youth-generated policy ideas take a systems approach, we analyzed them using the Intervention Level Framework (ILF). The ILF ascribes actions to one of five system levels, from Structural Elements, the least engaged with system change, up to Paradigm, which is the system's deepest held beliefs and thus the most difficult level at which to intervene. Of the 106 policy ideas generated by young people during the CO-CREATE project, 91 (86%) were categorized at the level of Structural Elements. This emphasis on operational rather than systems level responses echoes findings from a previous study on obesity strategies. Analyzing the distribution of systems level responses using the ILF has the potential to support more effective action on obesity by allowing identification of opportunities to strengthen systems level responses overall.publishedVersio

Associations between social media, adolescent mental health, and diet: A systematic review

SummarySocial media use is integral to many adolescents' lives. It brings benefits but can also have detrimental effects on both physical and mental health. We conducted a systematic review examining associations between social media use, adolescent mental health (including body image, self‐esteem, stress, interpersonal relationships and loneliness, anxiety, and depressive symptoms), and dietary outcomes. Quantitative studies published between 2019 and 2023 investigating both mental health and diet were searched in 11 databases. The risk of bias was appraised using ROBINS‐E. Data were narratively synthesized by type of association, PROGRESS‐Plus health equity characteristics, and related to social media influencers. Twenty‐one studies were included, of which only one focused on influencers. Sex/gender was the only equity characteristic assessed (n = 8), with mixed results. The findings suggest significant positive correlations between social media use and both depressive and disordered eating symptoms, body dissatisfaction, and anxiety. Four studies identified body image, self‐esteem, or anxiety as moderators acting between social media exposure and dietary outcomes. Policy interventions mitigating the impact of social media on adolescents—particularly body image and disordered eating—are needed, alongside follow‐up studies on causal pathways, the role of influencers, equity impacts, dietary intake, and the best measurement tools to use.</jats:p

Transcriptional profile of the homologous recombination machinery and characterization of the EhRAD51 recombinase in response to DNA damage in Entamoeba histolytica

<p>Abstract</p> <p>Background</p> <p>In eukaryotic and prokaryotic cells, homologous recombination is an accurate mechanism to generate genetic diversity, and it is also used to repair DNA double strand-breaks. <it>RAD52 </it>epistasis group genes involved in recombinational DNA repair, including <it>mre11, rad50, nsb1/xrs2, rad51, rad51c/rad57, rad51b/rad55, rad51d, xrcc2, xrcc3, rad52, rad54, rad54b/rdh54 </it>and <it>rad59 </it>genes, have been studied in human and yeast cells. Notably, the RAD51 recombinase catalyses strand transfer between a broken DNA and its undamaged homologous strand, to allow damaged region repair. In protozoan parasites, homologous recombination generating antigenic variation and genomic rearrangements is responsible for virulence variation and drug resistance. However, in <it>Entamoeba histolytica </it>the protozoan parasite responsible for human amoebiasis, DNA repair and homologous recombination mechanisms are still unknown.</p> <p>Results</p> <p>In this paper, we initiated the study of the mechanism for DNA repair by homologous recombination in the primitive eukaryote <it>E. histolytica </it>using UV-C (150 J/m²) irradiated trophozoites. DNA double strand-breaks were evidenced in irradiated cells by TUNEL and comet assays and evaluation of the EhH2AX histone phosphorylation status. In <it>E. histolytica </it>genome, we identified genes homologous to yeast and human RAD52 epistasis group genes involved in DNA double strand-breaks repair by homologous recombination. Interestingly, the <it>E. histolytica </it>RAD52 epistasis group related genes were differentially expressed before and after UV-C treatment. Next, we focused on the characterization of the putative recombinase EhRAD51, which conserves the typical architecture of RECA/RAD51 proteins. Specific antibodies immunodetected EhRAD51 protein in both nuclear and cytoplasmic compartments. Moreover, after DNA damage, EhRAD51 was located as typical nuclear <it>foci</it>-like structures in <it>E. histolytica </it>trophozoites. Purified recombinant EhRAD51 exhibited DNA binding and pairing activities and exchanging reactions between homologous strands <it>in vitro</it>.</p> <p>Conclusion</p> <p><it>E. histolytica </it>genome contains most of the RAD52 epistasis group related genes, which were differentially expressed when DNA double strand-breaks were induced by UV-C irradiation. In response to DNA damage, EhRAD51 protein is overexpressed and relocalized in nuclear <it>foci</it>-like structures. Functional assays confirmed that EhRAD51 is a <it>bonafide </it>recombinase. These data provided the first insights about the potential roles of the <it>E. histolytica </it>RAD52 epistasis group genes and EhRAD51 protein function in DNA damage response of this ancient eukaryotic parasite.</p

Learning from the CO-CREATE project: A protocol for systems thinking across research (STAR).

The CO-CREATE project aimed to work with young people to create, inform, and disseminate obesity-preventive evidence-based policies using a complex systems perspective. This paper draws lessons from this experience and proposes a protocol for embedding systems thinking within a research project. We first draw on existing systems thinking frameworks to analyze how systems thinking was translated across CO-CREATE, including the flow and relationship between the work packages and in the methods used. We then take the lessons from CO-CREATE and the principles of existing systems thinking frameworks-which focus on various points of intervention planning and delivery but not on research projects as a whole-to formulate a protocol for embedding systems thinking across a research project. Key lessons for future planning and delivery of systems-oriented research projects include incorporating "boundary critique" by capturing key stakeholder (adolescent) values and concerns; working to avoid social exclusion; ensuring methodological pluralism to allow for reflection and responsiveness (with methods ranging from group model building, Photovoice, and small group engagement); getting policy recipients to shape key questions by understanding their views on the critical drivers of obesity early on in the project; and providing opportunity for intraproject reflection along the way

The influence of temperature on the development of Baltic Sea sprat (Sprattus sprattus) eggs and yolk sac larvae

In spring 2004 and 2005 we performed two sets of experiments with Baltic sprat (Sprattus sprattus balticus Schneider) eggs and larvae from the Bornholm Basin simulating ten different temperature scenarios. The goal of the present study was to analyse and parameterise temperature effects on the duration of developmental stages, on the timing of important ontogenetic transitions, growth during the yolk sac phase as well as on the survival success of eggs and early larval stages. Egg development and hatching showed exponential temperature dependence. No hatching was observed above 14.7°C and hatching success was significantly reduced below 3.4°C. Time to eye pigmentation, as a proxy for mouth gape opening, decreased with increasing temperatures from 17 days post hatch at 3.4°C to 7 days at 13°C whereas the larval yolk sac phase was shortened from 20 to 10 days at 3.8 and 10°C respectively. Maximum survival duration of non-fed larvae was 25 days at 6.8°C. Comparing the experimental results of Baltic sprat with existing information on sprat from the English Channel and North Sea differences were detected in egg development rate, thermal adaptation and in yolk sac depletion rate (YSDR). Sprat eggs from the English Channel showed significantly faster development and the potential to develop at temperatures higher than 14.7°C. North Sea sprat larvae were found to have a lower YSDR compared to larvae from the Baltic Sea. In light of the predictions for global warming, Baltic sprat stocks could experience improved conditions for egg development and surviva

HUS and atypical HUS

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy characterized by intravascular hemolysis, thrombocytopenia, and acute kidney failure. HUS is usually categorized as typical, caused by Shiga toxin-producing Escherichia coli (STEC) infection, as atypical HUS (aHUS), usually caused by uncontrolled complement activation, or as secondary HUS with a coexisting disease. In recent years, a general understanding of the pathogenetic mechanisms driving HUS has increased. Typical HUS (ie, STEC-HUS) follows a gastrointestinal infection with STEC, whereas aHUS is associated primarily with mutations or autoantibodies leading to dysregulated complement activation. Among the 30% to 50% of patients with HUS who have no detectable complement defect, some have either impaired diacylglycerol kinase epsilon (DGK epsilon) activity, cobalamin C deficiency, or plasminogen deficiency. Some have secondary HUS with a coexisting disease or trigger such as autoimmunity, transplantation, cancer, infection, certain cytotoxic drugs, or pregnancy. The common pathogenetic features in STEC-HUS, aHUS, and secondary HUS are simultaneous damage to endothelial cells, intravascular hemolysis, and activation of platelets leading to a procoagulative state, formation of microthrombi, and tissue damage. In this review, the differences and similarities in the pathogenesis of STEC-HUS, aHUS, and secondaryHUSare discussed. Commonfor the pathogenesis seems to be the vicious cycle of complement activation, endothelial cell damage, platelet activation, and thrombosis. This process can be stopped by therapeutic complement inhibition in most patients with aHUS, but usually not those with a DGK epsilon mutation, and some patients with STEC-HUS or secondary HUS. Therefore, understanding the pathogenesis of the different forms of HUS may prove helpful in clinical practice.Peer reviewe