40,704 research outputs found
On Perturbations of Unitary Minimal Models by Boundary Condition Changing Operators
In this note we consider boundary perturbations in the A-Series unitary
minimal models by phi_{r,r+2} fields on superpositions of boundaries. In
particular, we consider perturbations by boundary condition changing operators.
Within conformal perturbation theory we explicitly map out the space of
perturbative renormalisation group flows for the example phi_{1,3} and find
that this sheds light on more general phi_{r,r+2} perturbations. Finally, we
find a simple diagrammatic representation for the space of flows from a single
Cardy boundary condition.Comment: 27 pages, 10 figure
Synthesis and characterisation of Fe<sub>6</sub> and Fe<sub>12</sub> clusters using bicine
Reaction of bicine {BicH3, N,N-bis(2-hydroxyethyl)glycine} with an Fe(III) oxo-centered pivalate triangle in MeCN in the presence of Et<sub>2</sub>NH yields [Et<sub>2</sub>NH<sub>2</sub>]<sub>2</sub>[Fe<sub>6</sub>O<sub>2</sub>(OH)<sub>2</sub>(Bic)<sub>2</sub>(O<sub>2</sub>CCMe<sub>3</sub>)<sub>8</sub>], which possesses an S = 5 ground state.
Changing the base to NaOMe produces [Fe<sub>12</sub>O<sub>4</sub>(Bic)<sub>4</sub>(HBic)<sub>4</sub>(O<sub>2</sub>CCMe<sub>3</sub>)<sub>8</sub>], which contains two Fe6 units bridged by the carboxylate arms from the bicine ligands. The complex displays strong antiferromagnetic coupling leading to an S = 0 ground state
Defect flows in minimal models
In this paper we study a simple example of a two-parameter space of
renormalisation group flows of defects in Virasoro minimal models. We use a
combination of exact results, perturbation theory and the truncated conformal
space approach to search for fixed points and investigate their nature. For the
Ising model, we confirm the recent results of Fendley et al. In the case of
central charge close to one, we find six fixed points, five of which we can
identify in terms of known defects and one of which we conjecture is a new
non-trivial conformal defect. We also include several new results on exact
properties of perturbed defects and on the renormalisation group in the
truncated conformal space approach.Comment: 35 pages, 21 figures. 1 reference adde
Variations in agronomic and grain quality traits of rice grown under irrigated lowland conditions in West Africa
Rice breeding in West Africa has been largely skewed toward yield enhancement and stress tolerance. This has led to the variable grain quality of locally produced rice in the region. This study sought to assess variations in the agronomic and grain quality traits of some rice varieties grown in this region, with a view to identifying sources of high grain yield and quality that could serve as potential donors in their breeding programs. Fortyâfive varieties were grown under irrigated conditions in Benin and Senegal with two trials in each country. There were wide variations in agronomic and grain quality traits among the varieties across the trials. Cluster analysis using paddy yield, head rice yield, and chalkiness revealed that 68% of the total variation could be explained by five varietal groupings. One group comprising seven varieties (Afrihikari, BG90â2, IR64, Sahel 108, WAT311âWASâBâBâ23â7â1, WAT339âTGRâ5â2, and WITA 10) had high head rice yield and low chalkiness. Of the varieties in this group, Sahel 108 had the highest paddy yield in three of the four trials. IR64 and Afrihikari had intermediate and low amylose content, respectively, with the rest being highâamylose varieties. Another group of varieties consisting of B6144FâMRâ6â0â0, C74, IR31851â96â2â3â2â1, ITA222, Jaya, Sahel 305, WITA 1, and WITA 2 had high paddy yield but poor head rice yield and chalkiness. The use of materials from these two groups of varieties could accelerate breeding for high yielding rice varieties with better grain quality for local production in West Africa
Interactions between the endocrine and immune systems in locusts
The prophenoloxidase cascade in the haemolymph of mature adult Locusta migratoria migratorioides (R & F) is activated in response to injection of laminarin, a -1,3 glucan. Co-injection of adipokinetic hormone-I (Lom-AKH-I) and laminarin prolongs the activation of the enzyme in a dose-dependent manner. However, injections of bacterial lipopolysaccharide (LPS) do not activate prophenoloxidase unless AKH is co-injected, when there is a dose-dependent increase in the level of phenoloxidase that persists in the haemolymph for several hours. Even when AKH is co-injected, the highest levels of phenoloxidase activity are always greater after injection of laminarin than after LPS, and these two immunogens must activate the prophenoloxidase cascade by quite distinct pathways. In the present study, interactions between the endocrine and immune systems were examined with respect to activation of prophenoloxidase and the formation of nodules: injection of LPS induces nodule formation in adult locusts. With LPS from Pseudomonas aeruginosa, nodules form exclusively in dense accumulations in the anterior portion of the abdomen on either side of the dorsal blood vessel associated with the dorsal diaphragm. However, with LPS from Escherichia coli, fewer nodules are formed but with a similar distribution, except that occasionally some nodules are aligned additionally on either side of the ventral nerve cord. Co-injection of Lom-AKH-I with LPS from either bacteria stimulates greater numbers of nodules to be formed. This effect of coinjection of AKH on nodule formation is seen at low doses of hormone with only 0.3 or 0.4 pmol of Lom-AKH-1, respectively, increasing the number of nodules by 50%. Injections of octopamine or 5-hydroxytryptamine do not mimic either of the actions of Lom-AKH-I described here. Co-injection of an angiotensin-converting enzyme inhibitor, captopril, reduces nodule formation in response to injections of LPS but has no effect on the activation of phenoloxidase. Co-injection of an inhibitor of eicosanoid synthesis, dexamethasone, with LPS influences nodule formation (with or without AKH) in different ways according to the dose of dexamethasone used, but does not affect activation of prophenoloxidase. Eicosanoid synthesis is important for nodule formation, but not for the activation of the prophenoloxidase cascade in locust haemolymph
A structure in the early Universe at z 1.3 that exceeds the homogeneity scale of the R-W concordance cosmology
A Large Quasar Group (LQG) of particularly large size and high membership has been identified in the DR7QSO catalogue of the Sloan Digital Sky Survey. It has characteristic size (volume^1/3) ~ 500 Mpc (proper size, present epoch), longest dimension ~ 1240 Mpc, membership of 73 quasars, and mean redshift = 1.27. In terms of both size and membership it is the most extreme LQG found in the DR7QSO catalogue for the redshift range 1.0 = 1.28, which is itself one of the more extreme examples. Their boundaries approach to within ~ 2 deg (~ 140 Mpc projected). This new, huge LQG appears to be the largest structure currently known in the early universe. Its size suggests incompatibility with the Yadav et al. scale of homogeneity for the concordance cosmology, and thus challenges the assumption of the cosmological principle
Guidelines for the management of the foot health problems associated with rheumatoid arthritis
Background. Rheumatoid arthritis (RA) as a chronic systemic disease, commonly affects the feet, impacting
negatively on patients' quality of life. Specialist podiatrists have a prime role to play in the assessment and
management of foot and ankle problems within this patient group. However, it has been identified that in many
areas there is no specialist podiatry service, with many patients being managed by nonâspecialist podiatrists.
Therefore, the North West Clinical Effectiveness Group for the Foot in Rheumatic Diseases (NWCEG) identified
the need to develop âpractitioner facingâ guidelines for the management of specific foot health problems associated
with RA.
Methods. Members of a guideline development group from the NWCEG each reviewed the evidence for specific
aspects of the assessment and management of foot problems. Where evidence was lacking, âexpert opinionâ was
obtained from the members of the NWCEG and added as a consensus on current and best practice. An iterative
approach was employed, with the results being reviewed and revised by all members of the group and external
reviewers before the final guideline document was produced.
Results. The management of specific foot problems (callus, nail pathology, ulceration) and the use of specific
interventions (foot orthoses, footwear, patient education, steroid injection therapy) are detailed and standards in
relation to each are provided. A diagrammatic screening pathway is presented, with the aim of guiding nonspecialist
podiatrists through the complexity of assessing and managing those patients with problems requiring
input from a specialist podiatrist and other members of the rheumatology multidisciplinary team.
Conclusion. This pragmatic approach ensured that the guidelines were relevant and applicable to current practice
as âbest practiceâ, based on the available evidence from the literature and consensus expert opinion. These
guidelines provide both specialist and nonâspecialist podiatrists with the essential and âgold standardâ aspects of
managing people with RAârelated foot problems
Disorder-Induced Shift of Condensation Temperature for Dilute Trapped Bose Gases
We determine the leading shift of the Bose-Einstein condensation temperature
for an ultracold dilute atomic gas in a harmonic trap due to weak disorder by
treating both a Gaussian and a Lorentzian spatial correlation for the quenched
disorder potential. Increasing the correlation length from values much smaller
than the geometric mean of the trap scale and the mean particle distance to
much larger values leads first to an increase of the positive shift to a
maximum at this critical length scale and then to a decrease.Comment: Author information under
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