450 research outputs found
Transnational environmental crime threatens sustainable development
Transnational environmental crime has become the largest financial driver of social conflict, with severe implications for peace and security. Sustainable-development frameworks need to overtly recognize and mitigate the risks posed by transnational environmental crime to environmental security
A reactivity-selectivity study of the Friedel-Crafts acetylation of 3,3′-dimethylbiphenyl and the oxidation of the acetyl derivatives
<p>Abstract</p> <p>Background</p> <p>Friedel-Crafts acetylation is an important route to aromatic ketones, in research laboratories and in industry. The acetyl derivatives of 3,3′-dimethylbiphenyl (3,3′-dmbp) have applications in the field of liquid crystals and polymers and may be oxidized to the dicarboxylic acids and derivatives that are of interest in cancer treatment.</p> <p>Findings</p> <p>The effect of solvent and temperature on the selectivity of monoacetylation of 3,3’-dmbp by the Perrier addition procedure was studied using stoichiometric amounts of reagents. 4-Ac-3,3′-dmbp was formed almost quantitatively in boiling 1,2-dichloroethane and this is almost twice the yield hitherto reported. Using instead a molar ratio of substrate:AcCl:AlCl<sub>3</sub> equal to 1:4:4 or 1:6:6 in boiling 1,2-dichloroethane, acetylation afforded 4,4′- and 4,6′-diacetyl-3,3′-dmbp in a total yield close to 100%. The acetyl derivatives were subsequently converted to the carboxylic acids by hypochlorite oxidation. The relative stabilities of the isomeric products and the corresponding σ-complexes were studied by DFT calculations and the data indicated that mono- and diacetylation followed different mechanisms.</p> <p>Conclusions</p> <p>Friedel-Crafts acetylation of 3,3′-dmbp using the Perrier addition procedure in boiling 1,2-dichloroethane was found to be superior to other recipes. The discrimination against the 6-acetyl derivative during monoacetylation seems to reflect a mechanism including an AcCl:AlCl<sub>3</sub> complex or larger agglomerates as the electrophile, whereas the less selective diacetylations of the deactivated 4-Ac-3,3′-dmbp are suggested to include the acetyl cation as the electrophile. The DFT data also showed that complexation of intermediates and products with AlCl<sub>3</sub> does not seem to be important in determining the mechanism.</p
Kepler eclipsing binary stars. VII. the catalogue of eclipsing binaries found in the entire Kepler data set
The primary Kepler Mission provided nearly continuous monitoring of ~200,000 objects with unprecedented photometric precision. We present the final catalog of eclipsing binary systems within the 105 deg2 Kepler field of view. This release incorporates the full extent of the data from the primary mission (Q0-Q17 Data Release). As a result, new systems have been added, additional false positives have been removed, ephemerides and principal parameters have been recomputed, classifications have been revised to rely on analytical models, and eclipse timing variations have been computed for each system. We identify several classes of systems including those that exhibit tertiary eclipse events, systems that show clear evidence of additional bodies, heartbeat systems, systems with changing eclipse depths, and systems exhibiting only one eclipse event over the duration of the mission. We have updated the period and galactic latitude distribution diagrams and included a catalog completeness evaluation. The total number of identified eclipsing and ellipsoidal binary systems in the Kepler field of view has increased to 2878, 1.3% of all observed Kepler targets
Possible origins of macroscopic left-right asymmetry in organisms
I consider the microscopic mechanisms by which a particular left-right (L/R)
asymmetry is generated at the organism level from the microscopic handedness of
cytoskeletal molecules. In light of a fundamental symmetry principle, the
typical pattern-formation mechanisms of diffusion plus regulation cannot
implement the "right-hand rule"; at the microscopic level, the cell's
cytoskeleton of chiral filaments seems always to be involved, usually in
collective states driven by polymerization forces or molecular motors. It seems
particularly easy for handedness to emerge in a shear or rotation in the
background of an effectively two-dimensional system, such as the cell membrane
or a layer of cells, as this requires no pre-existing axis apart from the layer
normal. I detail a scenario involving actin/myosin layers in snails and in C.
elegans, and also one about the microtubule layer in plant cells. I also survey
the other examples that I am aware of, such as the emergence of handedness such
as the emergence of handedness in neurons, in eukaryote cell motility, and in
non-flagellated bacteria.Comment: 42 pages, 6 figures, resubmitted to J. Stat. Phys. special issue.
Major rewrite, rearranged sections/subsections, new Fig 3 + 6, new physics in
Sec 2.4 and 3.4.1, added Sec 5 and subsections of Sec
How inclusive can innovation and development be in the twenty-first century?
Innovation is crucial for development. Addressing twenty-first century developmental challenges requires innovative processes and products, which help in reducing and/or eliminating the gap between rich and poor in the society. Such innovations can meet basic needs of low- and middle-income groups in developing countries, providing them with capabilities to function. The aim of this paper is to answer the question of how inclusive (of people and places) innovation and development can be in the twenty-first century. The paper therefore reviews new models of innovation for development, including ‘frugal’ and ‘grassroots’ or ‘below the radar’ innovation models. The argument put forward is that their inclusiveness depends not only on their diffusion to the poor but also on their generation according to principles of participation and equity derived from contemporary theories of global justice. These are conditions with direct impact on meeting the poor’s basic needs and increasing their capabilities to function
Mental health and behaviour of students of public health and their correlation with social support: a cross-sectional study
<p>Abstract</p> <p>Background</p> <p>Future public health professionals are especially important among students partly because their credibility in light of their professional messages and activities will be tested daily by their clients; and partly because health professionals' own lifestyle habits influence their attitudes and professional activities. A better understanding of public health students' health and its determinants is necessary for improving counselling services and tailoring them to demand. Our aim was to survey public health students' health status and behaviour with a focus on mental health.</p> <p>Methods</p> <p>A cross-sectional study was carried out among public health students at 1-5-years (<it>N </it>= 194) with a self-administered questionnaire that included standardized items on demographic data, mental wellbeing characterized by sense of coherence (SoC) and psychological morbidity, as well as health behaviour and social support. Correlations between social support and the variables for mental health, health status and health behaviour were characterized by pairwise correlation.</p> <p>Results</p> <p>The response rate was 75% and represented students by study year, sex and age in the Faculty. Nearly half of the students were non-smokers, more than one quarter smoked daily. Almost one-fifth of the students suffered from notable psychological distress. The proportion of these students decreased from year 1 to 5. The mean score for SoC was 60.1 and showed an increasing trend during the academic years. 29% of the students lacked social support from their student peers. Significant positive correlation was revealed between social support and variables for mental health. Psychological distress was greater among female public health students than in the same age female group of the general population; whereas the lack of social support was a more prevalent problem among male students.</p> <p>Conclusions</p> <p>Health status and behaviour of public health students is similar to their non-students peers except for their worse mental health. Future public health professionals should be better prepared for coping with the challenges they face during their studies. Universities must facilitate this process by providing helping services targeted at those with highest risk, and developing training to improve coping skills. Social support is also a potentially amenable determinant of mental health during higher education.</p
When increasing population density can promote the evolution of metabolic cooperation.
This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.Microbial cooperation drives ecological and epidemiological processes and is affected by the ecology and demography of populations. Population density influences the selection for cooperation, with spatial structure and the type of social dilemma, namely public-goods production or self-restraint, shaping the outcome. While existing theories predict that in spatially structured environments increasing population density can select either for or against cooperation, experimental studies with both public-goods production and self-restraint systems have only ever shown that increasing population density favours cheats. We suggest that the disparity between theory and empirical studies results from experimental procedures not capturing environmental conditions predicted by existing theories to influence the outcome. Our study resolves this issue and provides the first experimental evidence that high population density can favour cooperation in spatially structured environments for both self-restraint and public-goods production systems. Moreover, using a multi-trait mathematical model supported by laboratory experiments we extend this result to systems where the self-restraint and public-goods social dilemmas interact. We thus provide a systematic understanding of how the strength of interaction between the two social dilemmas and the degree of spatial structure within an environment affect selection for cooperation. These findings help to close the current gap between theory and experiments.RJL and IG: European Research Council No. 647292
MathModExp. BJP: Engineering and Physical Sciences Research
Council Doctoral training grant studentship
How service‐users with intellectual disabilities understand challenging behaviour and approaches to managing it
Background This study explored understandings that service‐users with intellectual disabilities and challenging behaviour held around their behaviour, what shaped these understandings, and the relationship between how behaviours are managed and well‐being. Methods Eight participants (three female, five male) partook in individual semi‐structured qualitative interviews. Interviews were transcribed and analysed using interpretative phenomenological analysis. Results Three master themes emerged from this analysis: (a) challenging behaviour can be explained via an internal or external frame of reference, with each framework having different implications for how participants attempted to manage behaviour. (b) Positive relationships provide a long‐term buffer to challenging behaviour, with positive relationships with family, staff and peers operating through different mechanisms to achieve this. (c) A greater ability to exert power and control in day‐to‐day life was perceived to reduce challenging behaviour in the long term. Conclusions Implications for practice are discussed
- …