22 research outputs found
A Scaling Hypothesis for Modulated Systems
We propose a scaling hypothesis for pattern-forming systems in which
modulation of the order parameter results from the competition between a
short-ranged interaction and a long-ranged interaction decaying with some power
of the inverse distance. With L being a spatial length characterizing
the modulated phase, all thermodynamic quantities are predicted to scale like
some power of L. The scaling dimensions with respect to L only depend on the
dimensionality of the system d and the exponent \alpha. Scaling predictions are
in agreement with experiments on ultra-thin ferromagnetic films and
computational results. Finally, our scaling hypothesis implies that, for some
range of values \alpha>d, Inverse-Symmetry-Breaking transitions may appear
systematically in the considered class of frustrated systems.Comment: 13 pages, 6 figures, expanded versio
Anomalous behavior of the irreversible magnetization and time relaxation in YBaCuO single crystals with splayed tracks
We have studied the angular dependence of the irreversible magnetization and
its time relaxation in YBaCuO single crystals with one or two
families of columnar defects inclined with respect to the c-axis. At high
magnetic fields, the magnetization shows the usual maximum centered at the mean
tracks' orientation and an associated minimum in the normalized relaxation
rate. In contrast, at low fields we observe an anomalous local minimum in the
magnetization and a maximum in the relaxation rate. We present a model to
explain this anomaly based on the slowing down of the creep processes arising
from the increase of the vortex-vortex interactions as the applied field is
tilted away from the mean tracks' direction.Comment: 15 pages, 6 figures. Submitted to Phys. Rev .
The Thyroid Hormone Receptors Modulate the Skin Response to Retinoids
[Background]: Retinoids play an important role in skin homeostasis and when administered topically cause skin hyperplasia, abnormal epidermal differentiation and inflammation. Thyroidal status in humans also influences skin morphology and function and we have recently shown that the thyroid hormone receptors (TRs) are required for a normal proliferative response to 12-O-tetradecanolyphorbol-13-acetate (TPA) in mice.
[Methodology/Principal Findings]: We have compared the epidermal response of mice lacking the thyroid hormone receptor binding isoforms TRα1 and TRβ to retinoids and TPA. Reduced hyperplasia and a decreased number of proliferating cells in the basal layer in response to 9-cis-RA and TPA were found in the epidermis of TR-deficient mice. Nuclear levels of proteins important for cell proliferation were altered, and expression of keratins 5 and 6 was also reduced, concomitantly with the decreased number of epidermal cell layers. In control mice the retinoid (but not TPA) induced parakeratosis and diminished expression of keratin 10 and loricrin, markers of early and terminal epidermal differentiation, respectively. This reduction was more accentuated in the TR deficient animals, whereas they did not present parakeratosis. Therefore, TRs modulate both the proliferative response to retinoids and their inhibitory effects on skin differentiation. Reduced proliferation, which was reversed upon thyroxine treatment, was also found in hypothyroid mice, demonstrating that thyroid hormone binding to TRs is required for the normal response to retinoids. In addition, the mRNA levels of the pro-inflammatory cytokines TNFα and IL-6 and the chemotactic proteins S1008A and S1008B were significantly elevated in the skin of TR knock-out mice after TPA or 9-cis-RA treatment and immune cell infiltration was also enhanced.
[Conclusions/significance]: Since retinoids are commonly used for the treatment of skin disorders, these results demonstrating that TRs regulate skin proliferation, differentiation and inflammation in response to these compounds
could have not only physiological but also therapeutic implications.This work was supported by grants BFU2007-62402 and SAF2008-00121 from Ministerio de Ciencia e Innovación, RD06/0020/0036 and RD06/0020/0029 from the Fondo de Investigaciones Sanitarias and by the European Grant CRESCENDO (FP-018652).Peer reviewe