32,231 research outputs found
Efficient heterocyclisation by (di)terpene synthases
While cyclic ether forming terpene synthases are known, the basis for such heterocyclisation is unclear. Here it is reported that numerous (di)terpene synthases, particularly including the ancestral ent-kaurene synthase, efficiently produce isomers of manoyl oxide from the stereochemically appropriate substrate. Accordingly, such heterocyclisation is easily accomplished by terpene synthases. Indeed, the use of single residue changes to induce production of the appropriate substrate in the upstream active site leads to efficient bifunctional enzymes producing isomers of manoyl oxide, representing novel enzymatic activity
Ten myths about character, virtue and virtue education – plus three well-founded misgivings
Initiatives to cultivate character and virtue in moral education at school continue to provoke sceptical responses. Most of those echo familiar misgivings about the notions of character, virtue and education in virtue – as unclear, redundant, old-fashioned, religious, paternalistic, anti-democratic, conservative, individualistic, relative and situation dependent. I expose those misgivings as ‘myths’, while at the same time acknowledging three better-founded historical, methodological and practical concerns about the notions in question
The needs of women and their partners regarding professional smoking cessation support during pregnancy:A qualitative study
BACKGROUND: Despite the health risks of smoking, some women continue during pregnancy. Professional smoking cessation support has shown to be effective in increasing the proportion of pregnant women who quit smoking. However, few women actually make use of professional support. AIM: To investigate the needs of women and their partners for professional smoking cessation support during pregnancy. METHODS: Semi-structured interviews were held with pregnant women and women who recently gave birth who smoked or quit smoking during pregnancy, and their partners, living in the north of the Netherlands. Recruitment was done via Facebook, LinkedIn, food banks, baby stores and healthcare professionals. The interviews were recorded, transcribed and thematically analysed. RESULTS: 28 interviews were conducted, 23 with pregnant women and women who recently gave birth, and five with partners of the women. The following themes were identified: 1) understanding women's needs, 2) responsibility without criticism, and 3) women and their social network. These themes reflect that women need support from an involved and understanding healthcare professional, who holds women responsible for smoking cessation but refrains from criticism. Women also prefer involvement of their social network in the professional support. CONCLUSION: For tailored support, the Dutch guideline for professional smoking cessation support may need some adaptations. The adaptations and recommendations, e.g. to involve women and their partners in the development of guidelines, might also be valuable for other countries. Women prefer healthcare professionals to address smoking cessation in a neutral way and to respect their autonomy in the decision to stop smoking
Topologies of nodal sets of random band limited functions
It is shown that the topologies and nestings of the zero and nodal sets of
random (Gaussian) band limited functions have universal laws of distribution.
Qualitative features of the supports of these distributions are determined. In
particular the results apply to random monochromatic waves and to random real
algebraic hyper-surfaces in projective space.Comment: 62 pages. Major revision following referee repor
Coral Disease and Health Workshop: Coral Histopathology II
The health and continued existence of coral reef ecosystems are threatened by an increasing array of environmental and anthropogenic impacts. Coral disease is one of the prominent causes of increased mortality among reefs globally, particularly in the Caribbean. Although over 40 different coral diseases and syndromes have been reported
worldwide, only a few etiological agents have been confirmed; most pathogens remain unknown and the dynamics of disease transmission, pathogenicity and mortality are not
understood. Causal relationships have been documented for only a few of the coral diseases, while new syndromes continue to emerge. Extensive field observations by coral
biologists have provided substantial documentation of a plethora of new pathologies, but our understanding, however, has been limited to descriptions of gross lesions with names reflecting these observations (e.g., black band, white band, dark spot). To determine etiology, we must equip coral diseases scientists with basic biomedical knowledge and specialized training in areas such as histology, cell biology and pathology. Only through
combining descriptive science with mechanistic science and employing the synthesis epizootiology provides will we be able to gain insight into causation and become equipped to handle the pending crisis.
One of the critical challenges faced by coral disease researchers is to establish a framework to systematically study coral pathologies drawing from the field of diagnostic
medicine and pathology and using generally accepted nomenclature. This process began in April 2004, with a workshop titled Coral Disease and Health Workshop: Developing Diagnostic Criteria co-convened by the Coral Disease and Health Consortium (CDHC), a working group organized under the auspices of the U.S. Coral Reef Task Force, and the International Registry for Coral Pathology (IRCP). The workshop was hosted by the U.S. Geological Survey, National Wildlife Health Center (NWHC) in Madison, Wisconsin and was focused on gross morphology and disease signs observed in the field. A resounding recommendation from the histopathologists participating in the workshop was the urgent need to develop diagnostic criteria that are suitable to move from gross observations to morphological diagnoses based on evaluation of microscopic anatomy. (PDF contains 92 pages
Low Temperature Anomaly in Mesoscopic Kondo Wires
We report the observation of an anomalous magnetoresistance in extremely
dilute quasi-one-dimensional AuFe wires at low temperatures, along with a
hysteretic background at low fields. The Kondo resistivity does not show the
unitarity limit down to the lowest temperature, implying uncompensated spin
states. We suggest that the anomalous magnetoresistance may be understood as
the interference correction from the accumulation of geometric phase in the
conduction electron wave function around the localized impurity spin.Comment: Four pages, five figure
Coalescing binary systems of compact objects: Dynamics of angular momenta
The end state of a coalescing binary of compact objects depends strongly on
the final total mass M and angular momentum J. Since gravitational radiation
emission causes a slow evolution of the binary system through quasi-circular
orbits down to the innermost stable one, in this paper we examine the
corresponding behavior of the ratio J/M^2 which must be less than 1(G/c) or
about 0.7(G/c) for the formation of a black hole or a neutron star
respectively. The results show cases for which, at the end of the inspiral
phase, the conditions for black hole or neutron star formation are not
satisfied. The inclusion of spin effects leads us to a study of precession
equations valid also for the calculation of gravitational waveforms.Comment: 22 pages, AASTeX and 13 figures in PostScrip
Dynamical aspects of inextensible chains
In the present work the dynamics of a continuous inextensible chain is
studied. The chain is regarded as a system of small particles subjected to
constraints on their reciprocal distances. It is proposed a treatment of
systems of this kind based on a set Langevin equations in which the noise is
characterized by a non-gaussian probability distribution. The method is
explained in the case of a freely hinged chain. In particular, the generating
functional of the correlation functions of the relevant degrees of freedom
which describe the conformations of this chain is derived. It is shown that in
the continuous limit this generating functional coincides with a model of an
inextensible chain previously discussed by one of the authors of this work.
Next, the approach developed here is applied to a inextensible chain, called
the freely jointed bar chain, in which the basic units are small extended
objects. The generating functional of the freely jointed bar chain is
constructed. It is shown that it differs profoundly from that of the freely
hinged chain. Despite the differences, it is verified that in the continuous
limit both generating functionals coincide as it is expected.Comment: 15 pages, LaTeX 2e + various packages, 3 figures. The title has been
changed and three references have been added. A large part of the manuscript
has been rewritten to improve readability. Chapter 4 has been added. It
contains the construction of the generating functional without the
shish-kebab approximation and a new derivation of the continuous limit of the
freely jointed bar chai
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