Ratchet Effect and Nonlinear Transport for Particles on Random Substrates with Crossed ac Drives

We show in simulations that overdamped interacting particles in two dimensions with a randomly disordered substrate can exhibit novel nonequilibrium transport phenomena including a transverse ratchet effect, where a combined dc drive and circular ac drive produce a drift velocity in the direction transverse to the applied dc drive. The random disorder does not break any global symmetry; however, in two dimensions, symmetry breaking occurs due to the chirality of the circular drive. In addition to inducing the transverse ratchet effect, increasing the ac amplitude also strongly affects the longitudinal velocity response and can produce what we term an overshoot effect where the longitudinal dc velocity is higher in the presence of the ac drive than it would be for a dc drive alone. We also find a dynamical reordering transition upon increasing the ac amplitude. In the absence of a dc drive, it is possible to obtain a ratchet effect when the combined ac drives produce particle orbits that break a reflection symmetry. In this case, as the ac amplitude increases, current reversals can occur. These effects may be observable for vortices in type II superconductors as well as for colloids interacting with random substrates.Comment: 11 pages, 16 postscript figure

Metastable states of a driven flux lattice in a superconductor with strong pins

The flux lattice driven by a uniform driving force in a superconductor with hot, strong, sharp and randomly distributed pinning centers, with applied magnetic field half the matching field is simulated. At low temperature both a non activated regime, where flux motion occurs within a robust percolative flux flow channel, and an activated regime are obtained depending on the sample preparation. These two regimes exhibit distinct resistivity and magnetic induction. In the non activated regime, a clear fingerprint is observed in the autocorrelation function of the longitudinal resitivity, which oscillates at a frequency close to the inverse lattice diffusion time.Comment: 6 figure

Registration of Textured Remote Sensing Images Using Directional Gabor Frames

In this paper we propose to utilize a new concept of discrete directional Gabor frames for automatic image registration. The directional Gabor representations have been shown to provide more accurate feature extraction than directional wavelet transforms for images where texture is the dominant feature. Initial experimental results are presented here which indicate that discrete directional Gabor frames exhibit strong correlations, which indicates that they are likely to improve the existing image registration toolbox

Loss of androgen signaling in mesenchymal sonic hedgehog responsive cells diminishes prostate development, growth, and regeneration.

Prostate embryonic development, pubertal and adult growth, maintenance, and regeneration are regulated through androgen signaling-mediated mesenchymal-epithelial interactions. Specifically, the essential role of mesenchymal androgen signaling in the development of prostate epithelium has been observed for over 30 years. However, the identity of the mesenchymal cells responsible for this paracrine regulation and related mechanisms are still unknown. Here, we provide the first demonstration of an indispensable role of the androgen receptor (AR) in sonic hedgehog (SHH) responsive Gli1-expressing cells, in regulating prostate development, growth, and regeneration. Selective deletion of AR expression in Gli1-expressing cells during embryogenesis disrupts prostatic budding and impairs prostate development and formation. Tissue recombination assays showed that urogenital mesenchyme (UGM) containing AR-deficient mesenchymal Gli1-expressing cells combined with wildtype urogenital epithelium (UGE) failed to develop normal prostate tissue in the presence of androgens, revealing the decisive role of AR in mesenchymal SHH responsive cells in prostate development. Prepubescent deletion of AR expression in Gli1-expressing cells resulted in severe impairment of androgen-induced prostate growth and regeneration. RNA-sequencing analysis showed significant alterations in signaling pathways related to prostate development, stem cells, and organ morphogenesis in AR-deficient Gli1-expressing cells. Among these altered pathways, the transforming growth factor β1 (TGFβ1) pathway was up-regulated in AR-deficient Gli1-expressing cells. We further demonstrated the activation of TGFβ1 signaling in AR-deleted prostatic Gli1-expressing cells, which inhibits prostate epithelium growth through paracrine regulation. These data demonstrate a novel role of the AR in the Gli1-expressing cellular niche for regulating prostatic cell fate, morphogenesis, and renewal, and elucidate the mechanism by which mesenchymal androgen-signaling through SHH-responsive cells elicits the growth and regeneration of prostate epithelium

Anxiety and Depression in Patients With Retinitis Pigmentosa

Purpose: Retinitis pigmentosa (RP) is a chronic progressive disease with no curative treatments. Understanding the variables involved with improving patients’ quality of life is important in managing this population. The literature investigating the relationship of anxiety and depression with RP relies on the analysis of smaller subset populations of patients with RP, and no study has quantified the effect size of the potential association. This study aims to elucidate and quantify the association between RP, anxiety, and depression. Methods: A retrospective case-control study was conducted of 6 093 833 medical records within the University of North Carolina Hospital and outpatient clinic system from July 1, 2004, to August 30, 2019. Patients with a diagnosis of RP, anxiety, and depression were identified within the Carolina Data Warehouse for Health by International Classification of Diseases, Ninth and Tenth Revision codes. Results: From the base population of 6 093 833 patients' medical records, 690 patients were diagnosed with RP, 253 065 with anxiety, and 232 541 with depression. Patients with RP have an odds ratio, adjusted for sex and age, of 4.915 (95% CI, 4.035-5.987) for having comorbid anxiety, 5.609 (95% CI, 4.622-6.807) for comorbid depression, and 4.130 (95% CI, 3.187-5.353) for comorbid anxiety and depression. Conclusions: Patients with RP have a higher prevalence of anxiety and depression, with increased odds of approximately 5 to 6 times for also carrying a diagnosis of anxiety or depression and about 4 times for carrying diagnoses of anxiety and depression compared with the general population

Driven vortices in 3D layered superconductors: Dynamical ordering along the c-axis

We study a 3D model of driven vortices in weakly coupled layered superconductors with strong pinning. Above the critical force $F_c$, we find a plastic flow regime in which pancakes in different layers are uncoupled, corresponding to a pancake gas. At a higher $F$, there is an ``smectic flow'' regime with short-range interlayer order, corresponding to an entangled line liquid. Later, the transverse displacements freeze and vortices become correlated along the c-axis, resulting in a transverse solid. Finally, at a force $F_s$ the longitudinal displacements freeze and we find a coherent solid of rigid lines.Comment: 4 pages, 3 postscript figure

Institutional Traps and Economic Growth

This paper's point of departure is that low-quality institutions, concentration of political power, and underdevelopment are persistent over time. Its analytical model views an equal distribution of political power as a commitment device to enhance institutional quality thereby promoting growth. The politically powerful coalition contemplates relinquishing of its power, weighing this advantageous consequence against the limit on own appropriative ability that it entails. The possibility of two developmental paths is exhibited: with concentration of political and economic power, low-quality institutions, and slow growth; and a more equal distribution of political and economic resources, high-quality institutions, and faster growth

Improved efficacy of newly formulated bacteriophages for management of bacterial spot on tomato

Bacteriophages are currently used as an alternative method for controlling bacterial spot disease on tomato incited by Xanthomonas campestris pv. vesicatoria. However, the efficacy of phage is greatly reduced due to its short residual activity on plant foliage. Three formulations that significantly increased phage longevity on the plant surface were tested in field and greenhouse trials: (i) PCF, 0.5% pregelatinized corn flour (PCF) + 0.5% sucrose; (ii) Casecrete, 0.5% Casecrete NH-400 + 0.5% sucrose + 0.25% PCF; and (iii) skim milk, 0.75% powdered skim milk + 0.5% sucrose. In greenhouse experiments, the nonformulated, PCF-, Casecrete-, and skim milk-formulated phage mixtures reduced disease severity on plants compared with the control by 1, 30, 51, and 62%, respectively. In three consecutive field trials, nonformulated phage caused 15, 20, and 9% reduction in disease on treated plants compared with untreated control plants, whereas plants treated with PCF- and Casecrete-formulated phage had 27, 32, and 12% and 30, 43, and 24% disease reduction, respectively. Plants receiving copper-mancozeb treatments were included in two field trials and had a 20% decrease in disease in the first trial and a 13% increase in the second one. Skim milk-formulated phage was tested only once and caused an 18% disease reduction. PCF-formulated phage was more effective when applied in the evening than in the morning, reducing disease on plants by 27 and 13%, respectively. The Casecrete-formulated phage populations were over 1,000-fold higher than the nonformulated phage populations 36 h after phage application

Slow relaxations and history dependence of the transport properties of layered superconductors

We study numerically the time evolution of the transport properties of layered superconductors after different preparations. We show that, in accordance with recent experiments in BSCCO performed in the second peak region of the phase diagram (Portier et al, 2001), the relaxation strongly depends on the initial conditions and is extremely slow. We investigate the dependence on the pinning center density and the perturbation applied. We compare the measurements to recent findings in tapped granular matter and we interpret our results with a rather simple picture.Comment: 4 pages, 4 fig