Non-Linear Effects in Resonant Tunneling; Bistabilities and Self-Sustained Oscillating Currents

We study non-linear phenomena in double barrier heterostructures. Systems in 3D under the effect of an external magnetic field along the current and 1D systems are analyzed. Non-linearities are reflected in the I-V characteristic curve as bistabilities, instabilities and time dependent oscillations of the currents. The nature of the non-linear behavior depends upon the parameters that define the system.Comment: 3 pages, 2 figures, accepted for publication in Superlattices and Microstructure

On minimal easily computable dimension group algebras, and group codes

Finite semisimple group algebras for which all the minimal ideals are easily computable dimension (ECD) are characterized and some lower bounds for the minimum Hamming distance of group codes in these algebras are offered. Examples illustrating the main results are provided

Major shifts at the range edge of marine forests: the combined effects of climate changes and limited dispersal

Global climate change is likely to constrain low latitude range edges across many taxa and habitats. Such is the case for NE Atlantic marine macroalgal forests, important ecosystems whose main structuring species is the annual kelp Saccorhiza polyschides. We coupled ecological niche modelling with simulations of potential dispersal and delayed development stages to infer the major forces shaping range edges and to predict their dynamics. Models indicated that the southern limit is set by high winter temperatures above the physiological tolerance of overwintering microscopic stages and reduced upwelling during recruitment. The best range predictions were achieved assuming low spatial dispersal (5 km) and delayed stages up to two years (temporal dispersal). Reconstructing distributions through time indicated losses of similar to 30% from 1986 to 2014, restricting S. polyschides to upwelling regions at the southern edge. Future predictions further restrict populations to a unique refugium in northwestern Iberia. Losses were dependent on the emissions scenario, with the most drastic one shifting similar to 38% of the current distribution by 2100. Such distributional changes might not be rescued by dispersal in space or time (as shown for the recent past) and are expected to drive major biodiversity loss and changes in ecosystem functioning.Electricity of Portugal (Fundo EDP para a Biodiversidade); FCT - Portuguese Science Foundation [PTDC/MAR-EST/6053/2014, EXTANT-EXCL/AAG-GLO/0661/2012, SFRH/BPD/111003/2015

On Grid Codes

If $A_{i}$ is finite alphabet for $i=1,...,n$, the Manhattan distance is defined in $\prod_{i=1}^{n}A_{i}$. A grid code is introduced as a subset of $\prod_{i=1}^{n}A_{i}$. Alternative versions of the Hamming and Gilbert-Varshamov bounds are presented for grid codes. If $A_{i}$ is a cyclic group for $i=1,...,n$, some bounds for the minimum Manhattan distance of codes that are cyclic subgroups of $\prod_{i=1}^{n}A_{i}$ are determined in terms of their minimum Hamming and Lee distances. Examples illustrating the main results are provided

Integration of supply and demand for water in Central Illinois urban areas

Water demand functions were estimated using two sets of data for Central Illinois -- community-wide data and household data. The community-wide data consist of total residential consumption for each of four pre-selected medium-sized cities in Central Illinois. The household data consist of residents from five cities who responded to a mail survey. This study investigates comparability of parameter estimates from the two approaches. If the parameter estimates are comparable, it would suggest water demand estimates need not require costly and time-consuming household surveys. Estimates of price elasticity are negative and less than unitary based on the two data sets used. The estimated price elasticity based on community-wide data is -.037, while using household data estimated price elasticities are in the range from -.I4 to -.16. Estimated income elasticities for central Illinois households are positive. The estimated income elasticity based on community-wide data is 1.57 while the estimated income elasticity based on household data ranges from .0759 to .316. In comparing results of the general demand model based on the two sets of data, there is wide disparity in the values of the estimated price and income elasticities. The reasons for these differences are not immediately apparent and warrant further investigation.U.S. Department of the InteriorU.S. Geological SurveyOpe

Pair formation in two electron correlated chains

We study two correlated electrons in a nearest neighbour tight- binding chain, with both on site and nearest neighbour interaction. Both the cases of parallel and antiparallel spins are considered. In addition to the free electron band for two electrons, there are correlated bands with positive or negative energy, depending on wheather the interaction parameters are repulsive or attractive. Electrons form bound states, with amplitudes that decay exponentially with separation. Conditions for such states to be filled at low temperatures are discussed.Comment: To appear in J. Phys: Condens. Matter 15 (2003

Effect of the hemicellulose in the properties of nanopaper.

The foldable, low thermal expansion, and optically transparent are main properties of paper produced with cellulose nanofibers (nanopaper), being able to be used ifl the development of flexible circuit technologies. In this context, this work evaluates the importance of hemicellulose in the properties of nanofiber paper (NFP). The hemicellulose extraction from Pinus sp bleached cellulose pulp was performed with NaOH 17.5% for 1.5 h. Thereafter, the pulp was washed with 8.3% NaOH, then was add 10% acetic acid until neutralization, and washed with water. The nanofibrils were obtained by mechanical defibrillation in a Super Masscoloider Masuko Sangyo mill. The NFP with the grammage of 40 and 50 g/m2 were produced by filtration and drying under pressure. The extraction process reduced 80% of xylose, 40% of mannose and 40% of galactose compared of the bleached cellulosic pulp. The NFPs with around 15% of hemicellulose are homogeneous and transparent, the interstices between the fibers, observed by scanning electron microscopy, are small enough to avoid light scattering, making the cellulosic material transparent. The NFP of 40 and 50 g/m2 had a thickness of 45 J..Im,water absorption of 63 and 34 g/m2, respectively. They did not present air permeability. NFP of 40 and 50 g/m2 without hemicellulose had a thickness of 76 and 87 um, water absorption of 128 g/m2 and air permeability of 202 and 384 s/100 em", respectively. The spaces created by the coalescence of the cellulose nanofibrils after the extraction of the hemicellulose result in the dispersion of the light and consequently in the opacity of the NFP. Extraction of hemicellulose reduced the tensile and bursting strength by 80%. Therefore, hemicellulose acts as an inhibitor of the coalescence of microfibrils, providing adhesion and increase of the mechanical properties

New challenges for Conservar Património

The current issue sets the beginning of a new stage of the journal Conservar Património. From its genesis until issue number 31, António João Cruz and Francisca Figueira were the Editor and Associate editor of the journal. We would like to highlight their great commitment and perseverance in the odyssey of setting up a periodic journal dedicated to the con- servation of heritage within the non-profit association ARP – Associação Profissional de Conservadores-restauradores de Portugal, and of being able to raise the journal to a level of recognized relevance and prominence in both national and international contexts

Hybrid organic–inorganic structures trigger the formation of primitive cell-like compartments

We would like to thank COST action Chemobrionics (CA17120) and DYNALIFE (CA21169) for giving us the opportunity to meet and conceive important ideas crucial for the manuscript preparation. We would also like to thank Department CIBIO Core Facilities which are supported by the European Regional Development Fund 2014 to 2020. This work was funded in part from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 824060 (project ACDC).Alkaline hydrothermal vents have become a candidate setting for the origins of life on Earth and beyond. This is due to several key features including the presence of gradients of temperature, redox potential, pH, the availability of inorganic minerals, and the existence of a network of inorganic pore spaces that could have served as primitive compartments. Chemical gardens have long been used as experimental proxies for hydrothermal vents. This paper investigates-10pc]Please note that the spelling of the following author name in the manuscript differs from the spelling provided in the article metadata: Richard J. G. Löffler. The spelling provided in the manuscript has been retained; please confirm. a set of prebiotic interactions between such inorganic structures and fatty alcohols. The integration of a medium-chain fatty alcohol, decanol, within these inorganic minerals, produced a range of emergent 3 dimensions structures at both macroscopic and microscopic scales. Fatty alcohols can be considered plausible prebiotic amphiphiles that might have assisted the formation of protocellular structures such as vesicles. The experiments presented herein show that neither chemical gardens nor decanol alone promote vesicle formation, but chemical gardens grown in the presence of decanol, which is then integrated into inorganic mineral structures, support vesicle formation. These observations suggest that the interaction of fatty alcohols and inorganic mineral structures could have played an important role in the emergence of protocells, yielding support for the evolution of living cells.COST (CA17120)DYNALIFE (CA21169)European Regional Development Fund 2014 to 2020European Union’s Horizon 2020 research and innovation programme 824060 (project ACDC

Evaluation of mechanical properties of composite of pinhão with polyrethane derived from castor oil.

Polymer matrix composites reinforced with pine nut shell that can be used in various application such as aerospace industry, automotive industry, electronics, and construction industry. The polyurethane derived from castor oil is a matrix that can be used to fabricate green composites, because it is derived from renewable resource, biodegradable and solvent free. The Paraná pine nut is a sub product of Paraná pine, cheap and there is a plenty of it because is a food residue. The aim of this study was to produce Paraná pine nut composites with polyurethane derived from castor oil. These composites were obtained by hot-pressing method. The mechanical proprieties were analyzed using three-point flexion test, density test and swelling test. The results indicate that these materials have mechanical resistance to be used as wooden partition panels