Letter from Edwards A. Park to George Sibley, November 10, 1851

Letter from Edwards A. Park to George Sibley, November 10, 1851. Park discusse

The roughness of stylolites: Implications of 3D high resolution topography measurements

Stylolites are natural pressure-dissolution surfaces in sedimentary rocks. We present 3D high resolution measurements at laboratory scales of their complex roughness. The topography is shown to be described by a self-affine scaling invariance. At large scales, the Hurst exponent is $\zeta_1 \approx 0.5$ and very different from that at small scales where $\zeta_2 \approx 1.2$. A cross-over length scale at around \L_c =1~mm is well characterized. Measurements are consistent with a Langevin equation that describes the growth of a stylolitic interface as a competition between stabilizing long range elastic interactions at large scales or local surface tension effects at small scales and a destabilizing quenched material disorder.Comment: 4 pages, 4 figure

Signal transduction and activator of transcription-3 (STAT3) in patients with colorectal cancer: associations with the phenotypic features of the tumour and host

Purpose: In patients with colorectal cancer (CRC), a high-density local inflammatory infiltrate response is associated with improved survival, whereas elevated systemic inflammatory responses are associated with poor survival. One potential unifying mechanism is the IL-6/JAK/STAT3 pathway. The present study examines the relationship between tumour total STAT3 and phosphorylated STAT3Tyr705 (pSTAT3) expression, host inflammatory responses and survival in patients undergoing resection of stage I-III CRC. Experimental Design: Immunohistochemical assessment of STAT3/pSTAT3 expression was performed using a tissue microarray and tumour cell expression divided into tertiles using the weighted histoscore. The relationship between STAT3/pSTAT3 expression and local inflammatory (CD3+, CD8+, CD45R0+, FOXP3+ T-cell density and Klintrup-Mäkinen grade) and systemic inflammatory responses and cancer-specific survival were examined. Results: 196 patients were included in the analysis. Cytoplasmic and nuclear STAT3 expression strongly correlated (r=0.363, P<0.001); nuclear STAT3 and pSTAT3 expression weakly correlated (r=0.130, P=0.068). Cytoplasmic STAT3 was inversely associated with the density of CD3+ (P=0.012), CD8+ (P=0.003) and FOXP3+ T-lymphocytes (P=0.002) within the cancer cell nests and was associated with an elevated systemic inflammatory response as measured by modified Glasgow Prognostic Score (mGPS2: 19% vs. 4%, P=0.004). The combination of nuclear STAT3/pSTAT3 stratified five-year survival from 81% to 62% (P=0.012), however was not associated with survival independent of venous invasion, tumour perforation or tumour budding. Conclusion In patients undergoing CRC resection, STAT3 expression was associated with adverse host inflammatory responses and reduced survival. Up-regulation of tumour STAT3 may be an important mechanism whereby the tumour deregulates local and systemic inflammatory responses

Universality class of the restricted solid-on-solid model with hopping

We study the restricted solid-on-solid (RSOS) model with finite hopping distance $l_{0}$, using both analytical and numerical methods. Analytically, we use the hard-core bosonic field theory developed by the authors [Phys. Rev. E {\bf 62}, 7642 (2000)] and derive the Villain-Lai-Das Sarma (VLD) equation for the $l_{0}=\infty$ case which corresponds to the conserved RSOS (CRSOS) model and the Kardar-Parisi-Zhang (KPZ) equation for all finite values of $l_{0}$. Consequently, we find that the CRSOS model belongs to the VLD universality class and the RSOS models with any finite hopping distance belong to the KPZ universality class. There is no phase transition at a certain finite hopping distance contrary to the previous result. We confirm the analytic results using the Monte Carlo simulations for several values of the finite hopping distance.Comment: 13 pages, 3 figure

Homoiterons and expansion in ribosomal RNAs

AbstractRibosomal RNAs in both prokaryotes and eukaryotes feature numerous repeats of three or more nucleotides with the same nucleobase (homoiterons). In prokaryotes these repeats are much more frequent in thermophile compared to mesophile or psychrophile species, and have similar frequency in both large RNAs. These features point to use of prokaryotic homoiterons in stabilization of both ribosomal subunits. The two large RNAs of eukaryotic cytoplasmic ribosomes have expanded to a different degree across the evolutionary ladder. The big RNA of the larger subunit (60S LSU) evolved expansion segments of up to 2400 nucleotides, and the smaller subunit (40S SSU) RNA acquired expansion segments of not more than 700 nucleotides. In the examined eukaryotes abundance of rRNA homoiterons generally follows size and nucleotide bias of the expansion segments, and increases with GC content and especially with phylogenetic rank. Both the nucleotide bias and frequency of homoiterons are much larger in metazoan and angiosperm LSU compared to the respective SSU RNAs. This is especially pronounced in the tetrapod vertebrates and seems to culminate in the hominid mammals. The stability of secondary structure in polyribonucleotides would significantly connect to GC content, and should also relate to G and C homoiteron content. RNA modeling points to considerable presence of homoiteron-rich double-stranded segments especially in vertebrate LSU RNAs, and homoiterons with four or more nucleotides in the vertebrate and angiosperm LSU RNAs are largely confined to the expansion segments. These features could mainly relate to protein export function and attachment of LSU to endoplasmic reticulum and other subcellular networks

Super-lattice, rhombus, square, and hexagonal standing waves in magnetically driven ferrofluid surface

Standing wave patterns that arise on the surface of ferrofluids by (single frequency) parametric forcing with an ac magnetic field are investigated experimentally. Depending on the frequency and amplitude of the forcing, the system exhibits various patterns including a superlattice and subharmonic rhombuses as well as conventional harmonic hexagons and subharmonic squares. The superlattice arises in a bicritical situation where harmonic and subharmonic modes collide. The rhombic pattern arises due to the non-monotonic dispersion relation of a ferrofluid

Derivation of continuum stochastic equations for discrete growth models

We present a formalism to derive the stochastic differential equations (SDEs) for several solid-on-solid growth models. Our formalism begins with a mapping of the microscopic dynamics of growth models onto the particle systems with reactions and diffusion. We then write the master equations for these corresponding particle systems and find the SDEs for the particle densities. Finally, by connecting the particle densities with the growth heights, we derive the SDEs for the height variables. Applying this formalism to discrete growth models, we find the Edwards-Wilkinson equation for the symmetric body-centered solid-on-solid (BCSOS) model, the Kardar-Parisi-Zhang equation for the asymmetric BCSOS model and the generalized restricted solid-on-solid (RSOS) model, and the Villain--Lai--Das Sarma equation for the conserved RSOS model. In addition to the consistent forms of equations for growth models, we also obtain the coefficients associated with the SDEs.Comment: 5 pages, no figur