Extremal maps of the universal hyperbolic solenoid

We show that the set of points in the Teichmuller space of the universal hyperbolic solenoid which do not have a Teichmuller extremal representative is generic (that is, its complement is the set of the first kind in the sense of Baire). This is in sharp contrast with the Teichmuller space of a Riemann surface where at least an open, dense subset has Teichmuller extremal representatives. In addition, we provide a sufficient criteria for the existence of Teichmuller extremal representatives in the given homotopy class. These results indicate that there is an interesting theory of extremal (and uniquely extremal) quasiconformal mappings on hyperbolic solenoids.Comment: LaTeX, 15 page

On the Zeros of Functions in the Bers Space

We present some results on the distribution of zeros of functions in the Bers space Q(D), showing how the distribution depends on the bounds of the growth of │ƒ(z)│ HS │z│ƒ → 1, for ƒ Є Q(D). We also exhibit an open and dense subset, M C Q(D), which has the property of uniform control over the number of zeros in disks of hyperbolic radius l containes in D

Assessing non-linear models for galaxy clustering I: unbiased growth forecasts from multipole expansion

We assess the performance of the Taruya, Nishimichi and Saito (TNS) model for the halo redshift space power spectrum, focusing on utilising mildly non-linear scales to constrain the growth rate of structure f. Using simulations with volume and number density typical of forthcoming Stage IV galaxy surveys, we determine ranges of validity for the model at redshifts z = 0.5 and z = 1. We proceed to perform a Bayesian MCMC analysis utilising the monopole, quadrupole, and hexadecapole spectra, followed by an exploratory Fisher matrix analysis. As previously noted in other forecasts as well as in real data analyses, we find that including the hexadecapole can significantly improve the constraints. However, a restricted range of scales is required for the hexadecapole in order for the growth parameter estimation to remain unbiased, limiting the improvement. We consistently quantify these effects by employing the multipole expansion formalism in both our Fisher and MCMC forecasts.Comment: 12 pages, 7 figures, 2 tables, accepted in OJ

Imaging the charge transport in arrays of CdSe nanocrystals

A novel method to image charge is used to measure the diffusion coefficient of electrons in films of CdSe nanocrystals at room temperature. This method makes possible the study of charge transport in films exhibiting high resistances or very small diffusion coefficients.Comment: 4 pages, 4 jpg figure

Testing the Warm Dark Matter paradigm with large-scale structures

We explore the impact of a LWDM cosmological scenario on the clustering properties of large-scale structure in the Universe. We do this by extending the halo model. The new development is that we consider two components to the mass density: one arising from mass in collapsed haloes, and the second from a smooth component of uncollapsed mass. Assuming that the nonlinear clustering of dark matter haloes can be understood, then from conservation arguments one can precisely calculate the clustering properties of the smooth component and its cross-correlation with haloes. We then explore how the three main ingredients of the halo calculations, the mass function, bias and density profiles are affected by WDM. We show that, relative to CDM: the mass function is suppressed by ~50%, for masses ~100 times the free-streaming mass-scale; the bias of low mass haloes can be boosted by up to 20%; core densities of haloes can be suppressed. We also examine the impact of relic thermal velocities on the density profiles, and find that these effects are constrained to scales r<1 kpc/h, and hence of little importance for dark matter tests, owing to uncertainties in the baryonic physics. We use our modified halo model to calculate the non-linear matter power spectrum, and find significant small-scale power in the model. However, relative to the CDM case, the power is suppressed. We then calculate the expected signal and noise that our set of LWDM models would give for a future weak lensing mission. We show that the models should in principle be separable at high significance. Finally, using the Fisher matrix formalism we forecast the limit on the WDM particle mass for a future full-sky weak lensing mission like Euclid or LSST. With Planck priors and using multipoles l<5000, we find that a lower limit of 2.6 keV should be easily achievable.Comment: Replaced with version accepted for publication in PRD. Inclusion of: new figure showing dependence of predictions on cut-off mass; new discussion of mass function; updated refs. 18 pages, 10 Figure

The corticotrophin-releasing factor/urocortin system regulates white fat browning in mice through paracrine mechanisms

Objectives: The corticotrophin-releasing factor (CRF)/urocortin system is expressed in the adipose tissue of mammals, but its functional role in this tissue remains unknown. Methods: Pharmacological manipulation of the activity of CRF receptors, CRF1 and CRF2, was performed in 3T3L1 white pre-adipocytes and T37i brown pre-adipocytes during in vitro differentiation. The expression of genes of the CRF/urocortin system and of markers of white and brown adipocytes was evaluated along with mitochondrial biogenesis and cellular oxygen consumption. Metabolic evaluation of corticosterone-deficient or supplemented Crhr1-null (Crhr1−/−) mice and their wild-type controls was performed along with gene expression analysis carried out in white (WAT) and brown (BAT) adipose tissues. Results: Peptides of the CRF/urocortin system and their cognate receptors were expressed in both pre-adipocyte cell lines. In vitro pharmacological studies showed an inhibition of the expression of the CRF2 pathway by the constitutive activity of the CRF1 pathway. Pharmacological activation of CRF2 and, to a lesser extent, inhibition of CRF1 signaling induced molecular and functional changes indicating transdifferentiation of white pre-adipocytes and differentiation of brown pre-adipocytes. Crhr1−/− mice showed increased expression of CRF2 and its agonist Urocortin 2 in adipocytes that was associated to brown conversion of WAT and activation of BAT. Crhr1−/− mice were resistant to diet-induced obesity and glucose intolerance. Restoring physiological circulating corticosterone levels abrogated molecular changes in adipocytes and the favorable phenotype of Crhr1−/− mice. Conclusions: Our findings suggest the importance of the CRF2 pathway in the control of adipocyte plasticity. Increased CRF2 activity in adipocytes induces browning of WAT, differentiation of BAT and is associated with a favorable metabolic phenotype in mice lacking CRF1. Circulating corticosterone represses CRF2 activity in adipocytes and may thus regulate adipocyte physiology through the modulation of the local CRF/urocortin system. Targeting CRF receptor signaling specifically in the adipose tissue may represent a novel approach to tackle obesity