145 research outputs found
Belnap-Dunn semantics for natural implicative expansions of Kleene's strong three-valued matrix with two designated values
27 p.A conditional is natural if it fulfils the three following conditions. (1) It coincides with the classical conditional when restricted to the classical values T and F; (2) it satisfies the Modus Ponens; and (3) it is assigned a designated value whenever the value assigned to its antecedent is less than or equal to the value assigned to its consequent. The aim of this paper is to provide a ābivalentā Belnap-Dunn semantics for all natural implicative expansions of Kleene's strong 3-valued matrix with two designated elements. (We understand the notion ānatural conditionalā according to N. Tomova, āA lattice of implicative extensions of regular Kleene's logicsā, Reports on Mathematical Logic, 47, 173ā182, 2012.)S
Exploring the use of problem-based learning in clinical embryology training
Problem-Based Learning (PBL) is an effective teaching method in many fields, in particular the medical disciplines. Clinical embryology deals with all aspects of assisted conception including insemination and embryo transfer. Clinical embryologists deal with daily issues that require troubleshooting and problem solving. The aim of this study was to explore and share the use of PBL teaching in a clinical embryology training programme. Students were given real-case scenarios and tasked with formulating a solution. A survey of questions to evaluate the PBL session was developed using a 5-point Likert scale. The scores obtained from these tests were assessed and analysed using Mann-Whitney U-tests (pā=ā0.05). The PBL teaching offered a format for students to develop critical problem-solving skills in a safe environment, which encourages learning through problem solving by creating a usable body of knowledge and clinical skill, which are imperative for clinical practice
The Class of All Natural Implicative Expansions of Kleeneās Strong Logic Functionally Equivalent to Åukasiewiczās 3-Valued Logic Å3
25 p.We consider the logics determined by the set of all natural implicative expansions of Kleeneās strong 3-valued matrix (with both only one and two designated values) and select the class of all logics functionally equivalent to Åukasiewiczās 3-valued logic Å3. The concept of a ānatural implicative matrixā is based upon the notion of a ānatural conditionalā defined in Tomova (Rep Math Log 47:173ā182, 2012).S
Toward visualization of nanomachines in their native cellular environment
The cellular nanocosm is made up of numerous types of macromolecular complexes or biological nanomachines. These form functional modules that are organized into complex subcellular networks. Information on the ultra-structure of these nanomachines has mainly been obtained by analyzing isolated structures, using imaging techniques such as X-ray crystallography, NMR, or single particle electron microscopy (EM). Yet there is a strong need to image biological complexes in a native state and within a cellular environment, in order to gain a better understanding of their functions. Emerging methods in EM are now making this goal reachable. Cryo-electron tomography bypasses the need for conventional fixatives, dehydration and stains, so that a close-to-native environment is retained. As this technique is approaching macromolecular resolution, it is possible to create maps of individual macromolecular complexes. X-ray and NMR data can be ādockedā or fitted into the lower resolution particle density maps to create a macromolecular atlas of the cell under normal and pathological conditions. The majority of cells, however, are too thick to be imaged in an intact state and therefore methods such as āhigh pressure freezingā with āfreeze-substitution followed by room temperature plastic sectioningā or ācryo-sectioning of unperturbed vitreous fully hydrated samplesā have been introduced for electron tomography. Here, we review methodological considerations for visualizing nanomachines in a close-to-physiological, cellular context. EM is in a renaissance, and further innovations and training in this field should be fully supported
Contemporaneous Observations of Direct and Raman Scattered O VI in Symbiotic Stars
Symbiotic stars are binary systems consisting of a hot star, typically a
white dwarf, and a cool giant companion. The wind from the cool star is ionized
by the radiation from the hot star, resulting in the characteristic combination
of sharp nebular emission lines and stellar molecular absorption lines in the
optical spectrum. Most of the emission lines are readily identifiable with
common ions. However, two strong, broad emission lines at
6825, 7082 defied identification with known atoms and ions. In 1989 Schmid made
the case that these long unidentified emission lines resulted from the Raman
scattering of the O VI resonance photons at 1032, 1038 by
neutral hydrogen.
We present contemporaneous far-UV and optical observations of direct and
Raman scattered O VI lines for nine symbiotic stars obtained with the Hopkins
Ultraviolet Telescope (Astro-2) and various ground-based telescopes. The O VI
emission lines are present in every instance in which the
6825, 7082 lines are present in support of the Schmid Raman scattering model.
We calculate scattering efficiencies and interpret the results in terms of the
Raman models. Additionally, we measure the flux of the Fe II fluorescence line
at 1776, which is excited by the O VI line at 1032, and
calculate the first estimates of the conversion efficiencies of this process.Comment: 48 pages, 5 figure
Use of directed acyclic graphs (DAGs) to identify confounders in applied health research: review and recommendations
Abstract Background Directed acyclic graphs (DAGs) are an increasingly popular approach for identifying confounding variables that require conditioning when estimating causal effects. This review examined the use of DAGs in applied health research to inform recommendations for improving their transparency and utility in future research. Methods Original health research articles published during 1999ā2017 mentioning ādirected acyclic graphsā (or similar) or citing DAGitty were identified from Scopus, Web of Science, Medline and Embase. Data were extracted on the reporting of: estimands, DAGs and adjustment sets, alongside the characteristics of each articleās largest DAG. Results A total of 234 articles were identified that reported using DAGs. A fifth (n = 48, 21%) reported their target estimand(s) and half (n = 115, 48%) reported the adjustment set(s) implied by their DAG(s). Two-thirds of the articles (n = 144, 62%) made at least one DAG available. DAGs varied in size but averaged 12 nodes [interquartile range (IQR): 9ā16, range: 3ā28] and 29 arcs (IQR: 19ā42, range: 3ā99). The median saturation (i.e. percentage of total possible arcs) was 46% (IQR: 31ā67, range: 12ā100). 37% (n = 53) of the DAGs included unobserved variables, 17% (n = 25) included āsuper-nodesā (i.e. nodes containing more than one variable) and 34% (n = 49) were visually arranged so that the constituent arcs flowed in the same direction (e.g. top-to-bottom). Conclusion There is substantial variation in the use and reporting of DAGs in applied health research. Although this partly reflects their flexibility, it also highlights some potential areas for improvement. This review hence offers several recommendations to improve the reporting and use of DAGs in future research
A Study of an Outburst in the Classical Symbiotic Star Z And in a Colliding-Wind Model
Two-dimensional gas-dynamical modeling of the mass-flow structure is used to
study the outburst development in the classical symbiotic star Z And. The
stage-by-stage rise of the light during the outburst can be explained in the
framework of the colliding winds model. We suggest a scenario for the
development of the outburst and study the possible influence of the changes of
the flow structure on the light of the system. The model variations of the
luminosity due to the formation of a system of shocks are in good agreement
with the observed light variations
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A prebiotic intervention study in children with autism spectrum disorders (ASDs)
Different dietary approaches, such as gluten and casein free diets, or the use of probiotics and prebiotics have been suggested in autistic spectrum disorders in order to reduce gastrointestinal (GI) disturbances. GI symptoms are of particular interest in this population due to prevalence and correlation with the severity of behavioural traits. Nowadays, there is lack of strong evidence about the effect of dietary interventions on these problems, particularly prebiotics. Therefore, we assessed the impact of exclusion diets and a 6-week BimunoĀ® galactooligosaccharide (B-GOSĀ®) prebiotic intervention in 30 autistic children.
RESULTS:
The results showed that children on exclusion diets reported significantly lower scores of abdominal pain and bowel movement, as well as lower abundance of Bifidobacterium spp. and Veillonellaceae family, but higher presence of Faecalibacterium prausnitzii and Bacteroides spp. In addition, significant correlations were found between bacterial populations and faecal amino acids in this group, compared to children following an unrestricted diet. Following B-GOSĀ® intervention, we observed improvements in anti-social behaviour, significant increase of Lachnospiraceae family, and significant changes in faecal and urine metabolites.
CONCLUSIONS:
To our knowledge, this is the first study where the effect of exclusion diets and prebiotics has been evaluated in autism, showing potential beneficial effects. A combined dietary approach resulted in significant changes in gut microbiota composition and metabolism suggesting that multiple interventions might be more relevant for the improvement of these aspects as well as psychological traits
The apicomplexan plastid and its evolution
Protistan species belonging to the phylum Apicomplexa have a non-photosynthetic secondary plastidāthe apicoplast. Although its tiny genome and even the entire nuclear genome has been sequenced for several organisms bearing the organelle, the reason for its existence remains largely obscure. Some of the functions of the apicoplast, including housekeeping ones, are significantly different from those of other plastids, possibly due to the organelleās unique symbiotic origin
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