3,167 research outputs found
Solvable Critical Dense Polymers on the Cylinder
A lattice model of critical dense polymers is solved exactly on a cylinder
with finite circumference. The model is the first member LM(1,2) of the
Yang-Baxter integrable series of logarithmic minimal models. The cylinder
topology allows for non-contractible loops with fugacity alpha that wind around
the cylinder or for an arbitrary number ell of defects that propagate along the
full length of the cylinder. Using an enlarged periodic Temperley-Lieb algebra,
we set up commuting transfer matrices acting on states whose links are
considered distinct with respect to connectivity around the front or back of
the cylinder. These transfer matrices satisfy a functional equation in the form
of an inversion identity. For even N, this involves a non-diagonalizable braid
operator J and an involution R=-(J^3-12J)/16=(-1)^{F} with eigenvalues
R=(-1)^{ell/2}. The number of defects ell separates the theory into sectors.
For the case of loop fugacity alpha=2, the inversion identity is solved exactly
for the eigenvalues in finite geometry. The eigenvalues are classified by the
physical combinatorics of the patterns of zeros in the complex
spectral-parameter plane yielding selection rules. The finite-size corrections
are obtained from Euler-Maclaurin formulas. In the scaling limit, we obtain the
conformal partition functions and confirm the central charge c=-2 and conformal
weights Delta_t=(t^2-1)/8. Here t=ell/2 and t=2r-s in the ell even sectors with
Kac labels r=1,2,3,...; s=1,2 while t is half-integer in the ell odd sectors.
Strikingly, the ell/2 odd sectors exhibit a W-extended symmetry but the ell/2
even sectors do not. Moreover, the naive trace summing over all ell even
sectors does not yield a modular invariant.Comment: 44 pages, v3: minor correction
Treatment for primary hypothyroidism: current approaches and future possibilities
Primary hypothyroidism is the most common endocrine disease. Although the diagnosis and treatment of hypothyroidism is often considered simple, there are large numbers of people with this condition who are suboptimally treated. Even in those people with hypothyroidism who are biochemically euthyroid on levothyroxine replacement there is a significant proportion who report poorer quality of life. This review explores the historical and current treatment options for hypothyroidism, reasons for and potential solutions to suboptimal treatment, and future possibilities in the treatment of hypothyroidism
FlowerNet: a gene expression correlation metwork for anther and pollen development
Floral formation, in particular anther and pollen development, is a complex biological process with critical importance for seed set and for targeted plant breeding. Many key transcription factors regulating this process have been identified; however, their direct role remains largely unknown. Using publicly available gene expression data from Arabidopsis (Arabidopsis thaliana), focusing on those studies that analyze stamen-, pollen-, or flower-specific expression, we generated a network model of the global transcriptional interactions (FlowerNet). FlowerNet highlights clusters of genes that are transcriptionally coregulated and therefore likely to have interacting roles. Focusing on four clusters, and using a number of data sets not included in the generation of FlowerNet, we show that there is a close correlation in how the genes are expressed across a variety of conditions, including male-sterile mutants. This highlights the important role that FlowerNet can play in identifying new players in anther and pollen development. However, due to the use of general floral expression data in FlowerNet, it also has broad application in the characterization of genes associated with all aspects of floral development and reproduction. To aid the dissection of genes of interest, we have made FlowerNet available as a community resource (http://www.cpib.ac.uk/ anther). For this resource, we also have generated plots showing anther/flower expression from a variety of experiments: These are normalized together where possible to allow further dissection of the resource
Periodic actin structures in neuronal axons are required to maintain microtubules
Axons are cable-like neuronal processes wiring the nervous system. They contain parallel bundles of microtubules as structural backbones, surrounded by regularly spaced actin rings termed the periodic membrane skeleton (PMS). Despite being an evolutionarily conserved, ubiquitous, highly ordered feature of axons, the function of PMS is unknown. Here we studied PMS abundance, organization, and function, combining versatile Drosophila genetics with superresolution microscopy and various functional readouts. Analyses with 11 actin regulators and three actin-targeting drugs suggest that PMS contains short actin filaments that are depolymerization resistant and sensitive to spectrin, adducin, and nucleator deficiency, consistent with microscopy-derived models proposing PMS as specialized cortical actin. Upon actin removal, we observed gaps in microtubule bundles, reduced microtubule polymerization, and reduced axon numbers, suggesting a role of PMS in microtubule organization. These effects become strongly enhanced when carried out in neurons lacking the microtubule-stabilizing protein Short stop (Shot). Combining the aforementioned actin manipulations with Shot deficiency revealed a close correlation between PMS abundance and microtubule regulation, consistent with a model in which PMS-dependent microtubule polymerization contributes to their maintenance in axons. We discuss potential implications of this novel PMS function along axon shafts for axon maintenance and regeneration
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