Compositional uniformity, domain patterning and the mechanism underlying nano-chessboard arrays

We propose that systems exhibiting compositional patterning at the nanoscale, so far assumed to be due to some kind of ordered phase segregation, can be understood instead in terms of coherent, single phase ordering of minority motifs, caused by some constrained drive for uniformity. The essential features of this type of arrangements can be reproduced using a superspace construction typical of uniformity-driven orderings, which only requires the knowledge of the modulation vectors observed in the diffraction patterns. The idea is discussed in terms of a simple two dimensional lattice-gas model that simulates a binary system in which the dilution of the minority component is favored. This simple model already exhibits a hierarchy of arrangements similar to the experimentally observed nano-chessboard and nano-diamond patterns, which are described as occupational modulated structures with two independent modulation wave vectors and simple step-like occupation modulation functions.Comment: Preprint. 11 pages, 11 figure

Turbulence Time Series Data Hole Filling using Karhunen-Loeve and ARIMA methods

Measurements of optical turbulence time series data using unattended instruments over long time intervals inevitably lead to data drop-outs or degraded signals. We present a comparison of methods using both Principal Component Analysis, which is also known as the Karhunen--Loeve decomposition, and ARIMA that seek to correct for these event-induced and mechanically-induced signal drop-outs and degradations. We report on the quality of the correction by examining the Intrinsic Mode Functions generated by Empirical Mode Decomposition. The data studied are optical turbulence parameter time series from a commercial long path length optical anemometer/scintillometer, measured over several hundred metres in outdoor environments.Comment: 8 pages, 9 figures, submitted to ICOLAD 2007, City University, London, U

Mouse model of colitis-associated colorectal cancer (CAC): Isolation and characterization of mucosal-associated lymphoid cells

Colorectal cancer (CRC) is the third most common malignancy worldwide presenting high mortality due to low treatment efficacy. Existing evidence indicates that inflammatory bowel disease (IBD) is associated with a higher risk of developing CRC. Many murine models of inflammation-related colon carcinogenesis (CAC) have been developed to study colon carcinogenesis and novel treatments. A commonly used model involves the combination of a single dose of azoxymethane (AOM), together with three cycles of the inflammatory agent dextran sodium sulfate (DSS) (5 days in drinking water followed by a two-week rest). Following this protocol, around 50% of the animals develop CRCs after 45 days and almost 100% of animals after 60 days. During CAC development, immune cells, cytokines, and other immune mediators are involved in both tumorigenesis and the elimination of cancer cells during immunotherapy. Thus, the study of mucosal immune responses (including lamina propria mononuclear cells and intraepithelial lymphocytes) is important to understand the role of the immune system during development and therapy in CRC. Single immune cell suspensions from lamina propria and epithelium can be purified combining selective tissue digestion and Percoll gradient centrifugation. Isolated cells can be characterized using flow cytometry by analyzing surface antigens or intracellular cytokines and cytotoxic mediators or employed for further investigations like comparative studies of mRNA expression, cell-proliferation assay, protein analysis, or even functional cytotoxicity assays. The CAC model is useful to study the involvement of immune cells not only during the carcinogenesis process but, in addition, during the treatment with novel immunotherapy protocols

Large Scale Instrumental Test Embankment on Uranium Tailings

The remediation of an inactive uranium mill tailings pile at the town of Andujar (Spain) has provided an opportunity to investigate the settlement characteristics of hydraulically-deposited uranium mill tailings. A test embankment was constructed on top of the existing tailings deposit and total stresses, settlements and pore pressures were measured. Settlements and pore pressure data were compared with the results obtained using an elastoplastic numerical model which allows the simulation of two dimensional consolidation processes. Backcalculated consolidation parameters were derived to provide agreement between the calculated and measured settlements and pore pressures. These parameters could then be used to predict the post-construction settlement of the remediated pile

Utilization of the Corncob Agro-Industrial Residue as a Potential Adsorbent in the Biosorption of Bisphenol-A

The presence of plastic waste in water bodies has led to a growing concern due to the impact on human health. Among the most important plastic additive molecules is bisphenol-A (BPA). On the other hand, micro-pollutant removal processes that make use of agro-industrial waste have aroused the interest of researchers. This is because the accumulation of lignocellulosic materials is also an environmental problem. The objective of this work is to use corncob agro-industrial residue (CC) as an adsorbent in the removal of BPA in aqueous matrix. The adsorption studies were carried out in reaction media containing the ground vegetable fiber and BPA solution in concentrations of 10, 25 and 50 mg L-1, as well as at pHs 3, 5, 7 and 9. Isotherms models and kinetic models were evaluated. The results showed that CC is a potent BPA adsorbent in aqueous solution, leading to about 90% of removal. The adsorption kinetics followed the pseudo-second order model and isotherm that best suited was the Lagmuir model, and the maximum adsorption capacity was 51.25 mg per gram of adsorbent fiber, after 20 min of contact. The thermogravimetric analysis allowed us to conclude that CC is a material resistant to high temperatures, due to the presence of a considerable amount of lignin. Finally, the best results of BPA removal efficiency by CC compared to activated carbon corroborate its high biosorption capacity

A likely magnetic activity cycle for the exoplanet host M dwarf GJ 3512

Current radial velocity data from specialized instruments contain a large amount of information that may pass unnoticed if their analysis is not accurate. The joint use of Bayesian inference tools and frequency analysis has been shown effective to reveal exoplanets but they have been used less frequently to investigate stellar activity. We intend to use radial velocity data of the exoplanet host star GJ 3512 to investigate its magnetic activity. Our study includes the analysis of the photometric data available. The main objectives of our work are to constrain the orbital parameters of the exoplanets in the system, to determine the current level of activity of the star and to derive an activity cycle length for it. An adaptive importance sampling method was used to determine the parameters of the exoplanets orbit. Generalized Lomb-Scargle periodograms were constructed with both radial velocity curve and photometric data. A careful analysis of the harmonic frequencies was conducted in each periodogram. Our fit to multiple Keplerian orbits constrained the orbital parameters of two giant gas planets orbiting the star GJ 3512. The host star showed an increase of its magnetic activity during the last observing campaign. The accurate fit of the radial velocity curve data to the multi-Keplerian orbit permitted to reveal the star rotation in the residuals of the best fit and estimate an activity cycle length of ~ 14 years.Comment: Accepted for publication in the Astronomical Journal. 15 pages, 11 figure

Cavitation and bubble collapse in hot asymmetric nuclear matter

The dynamics of embryonic bubbles in overheated, viscous and non-Markovian nuclear matter is studied. It is shown that the memory and the Fermi surface distortions significantly affect the hinderance of bubble collapse and determine a characteristic oscillations of the bubble radius. These oscillations occur due to the additional elastic force induced by the memory integral.Comment: Revtex file (10 pages) and 3 figure

Low temperature microwave emission from molecular clusters

We investigate the experimental detection of the electromagnetic radiation generated in the fast magnetization reversal in Mn12-acetate at low temperatures. In our experiments we used large single crystals and assemblies of several small single crystals of Mn12-acetate placed inside a cylindrical stainless steel waveguide in which an InSb hot electron device was also placed to detect the radiation. All this was set inside a SQUID magnetometer that allowed to change the magnetic field and measure the magnetic moment and the temperature of the sample as the InSb detected simultaneously the radiation emitted from the molecular magnets. Our data show a sequential process in which the fast inversion of the magnetic moment first occurs, then the radiation is detected by the InSb device, and finally the temperature of the sample increases during 15 ms to subsequently recover its original value in several hundreds of milliseconds.Comment: changed conten