Arsenate and arsenite differential toxicity in Tetrahymena thermophila.

A comparative analysis of toxicities of both arsenic forms (arsenite and arsenate) in the model eukaryotic microorganism Tetrahymena thermophila (ciliate protozoa) has shown the presence of various detoxification mechanisms and cellular effects comparable to those of animal cells under arsenic stress. In the wild type strain SB1969 arsenate is almost 2.5 times more toxic than arsenite.

Static internal representation of dynamic situations reveals time compaction in human cognition.

Introduction: The human brain has evolved under the constraint of survival in complex dynamic situations. It makes fast and reliable decisions based on internal representations of the environment. Whereas neural mechanisms involved in the internal representation of space are becoming known, entire spatiotemporal cognition remains a challenge.

Are mixed meat and vegetable protein products good alternatives for reducing meat consumption? A case study with burgers.

The principal motivations for the worldwide trend towards reducing meat consumption are health, the environment and animal welfare. The present study investigated the willingness of omnivores to introduce mixed (beef-vegetable protein) and 100% vegetable protein products into their diet. The participants (n = 251) were young adult omnivores who consumed meat at least once a week.

Correction to: Rain-Fed Granite Rock Basins Accumulate a High Diversity of Dormant Microbial Eukaryotes.

The original version of this article contained an erratum of omission in the Acknowledgments section.

Rain-Fed Granite Rock Basins Accumulate a High Diversity of Dormant Microbial Eukaryotes.

Rain fed granite rock basins are ancient geological landforms of worldwide distribution and structural simplicity. They support habitats that can switch quickly from terrestrial to aquatic along the year. Diversity of animals and plants, and the connexion between communities in different basins have been widely explored in these habitats, but hardly any research has been carried out on microorganisms.

Data on samara morphology and wind dispersal in the invasive tree .

The data presented in this paper is supporting the research article "Estimating wind dispersal potential in : The need to consider the three-dimensional structure of samaras" [1]. We analyzed the estimation of samara's wind dispersal potential through a group of morphological variables that succeed in describing the three-dimensional nature of samaras. We present here a dataset containing 8 morphological variables of 200 samaras belonging to 5 different individuals of the invasive tree (Mill.

Germination fitness of two temperate epiphytic ferns shifts under increasing temperatures and forest fragmentation.

Ferns are an important component of ecosystems around the world. Studies of the impacts that global changes may have on ferns are scarce, yet emerging studies indicate that some species may be particularly sensitive to climate change. The lack of research in this subject is much more aggravated in the case of epiphytes, and especially those that live under temperate climates.

Assessment of Effects of Si-Ca-P Biphasic Ceramic on the Osteogenic Differentiation of a Population of Multipotent Adult Human Stem Cells.

A new type of bioceramic with osteogenic properties, suitable for hard tissue regeneration, was synthesised. The ceramic was designed and obtained in the Nurse's A-phase-silicocarnotite subsystem. The selected composition was that corresponding to the eutectoid 28.

A New Biphasic Dicalcium Silicate Bone Cement Implant.

This study aimed to investigate the processing parameters and biocompatibility of a novel biphasic dicalcium silicate (C₂S) cement. Biphasic α´ + β-C₂S was synthesized by solid-state processing, and was used as a raw material to prepare the cement. In vitro bioactivity and biocompatibility studies were assessed by soaking the cement samples in simulated body fluid (SBF) and human adipose stem cell cultures.

Unravelling the interactions among microbial populations found in activated sludge during biofilm formation.

Microorganisms colonize surfaces and develop biofilms through interactions that are not yet thoroughly understood, with important implications for water and wastewater systems. This study investigated the interactions between N-acyl homoserine lactone (AHL)-producing bacteria, yeasts and protists, and their contribution to biofilm development. Sixty-one bacterial strains were isolated from activated sludge and screened for AHL production, with Aeromonas sp.

A simple mathematical model that describes the growth of the area and the number of total and viable cells in yeast colonies.

Unlabelled: We propose a model, based on the Gompertz equation, to describe the growth of yeasts colonies on agar medium. This model presents several advantages: (i) one equation describes the colony growth, which previously needed two separate ones (linear increase of radius and of the squared radius); (ii) a similar equation can be applied to total and viable cells, colony area or colony radius, because the number of total cells in mature colonies is proportional to their area; and (iii) its parameters estimate the cell yield, the cell concentration that triggers growth limitation and the effect of this limitation on the specific growth rate. To elaborate the model, area, total and viable cells of 600 colonies of Saccharomyces cerevisiae, Debaryomyces fabryi, Zygosaccharomyces rouxii and Rhodotorula glutinis have been measured.

Home dialysis and the Internet: designing an e-learning platform via brainstorming sessions.

Background: The resurgence of home hemodialysis (HHD) underlines the importance of educational programs. Brainstorming is a powerful tool for innovation, widely employed in industry but seldom used in medicine. The aim of this study was to define an e-learning Web platform for HHD patients via a brainstorming approach.

Analysis of the usefulness of biological parameters for the control of activated sludge wastewater treatment plants in an interlaboratory study context.

The quality of the sludge in Wastewater Treatment Plants (WWTPs) depends on the suitable colonization of the flocs by microorganisms. Due to the functional importance of these biological constituents, several biological or biological-related parameters have been commonly used for the control of depuration efficiency. According to national and international water regulation recommendations, interlaboratory studies have a great relevance to determine which parameters are more reliable for their extensive application in routine control.

Coupled wave analysis of holographically induced transparency (HIT) generated by two multiplexed volume gratings.

We present a holographic system that can be used to manipulate the group velocity of light pulses. The proposed structure is based on the multiplexing of two sequential holographic volume gratings, one in transmission and the other in reflection geometry, where one of the recording beams must be the same for both structures. As in other systems such as grating induced transparency (GIT) or coupled-resonator-induced transparency (CRIT), by using the coupled wave theory it is shown that this holographic structure represents a classical analogue of the electromagnetically induced transparency (EIT).

An explanation for the non-uniform grating effects during recording of diffraction gratings in photopolymers.

The recent results reported in reference 1 have produced an increased interest in explaining deviations from the ideal behavior of the energetic variation of the diffraction efficiency of holographic gratings. This ideal behavior occurs when uniform gratings are recorded, and the index modulation is proportional to the energetic exposure. As a result, a typical sin(2) curve is obtained reaching a maximum diffraction efficiency and saturation at or below this value.

Nonparaxial diffraction analysis of Airy and SAiry beams.

We theoretically analyze Airy beams by solving the exact vectorial Helmholtz equation using boundary conditions at a diffraction aperture. As result, the diffracted beams are obtained in the whole space; thus, we demonstrate that the parabolic trajectories are larger than those previously reported, showing that the Airy beams start to form before the Fourier plane. We also demonstrate the possibility of using a new type of Airy beams (SAiry beams) with finite energy that can be generated at the focal plane of the lens due to diffraction by a circular aperture of a spherical wave modified by a cubic phase.

Early frequency-dependent information processing and cortical control in the whisker pathway of the rat: electrophysiological study of brainstem nuclei principalis and interpolaris.

The rat facial whiskers form a high-resolution sensory apparatus for tactile information coding and are used by these animals for the exploration and perception of their environment. Previous work on the rat vibrissae system obtained evidence for vibration-based feature extraction by the whiskers, texture classification by the cortical neurons, and "low-pass", "high-pass", and "band-pass" filtering properties in both thalamic and cortical neurons. However, no data are available for frequency-dependent information processing in the brainstem sensory trigeminal complex (STC), the first relay station of the vibrissae pathway.

Theoretical approach to photoinduced inhomogeneous anisotropy in bacteriorhodopsin films.

The aim of this work was to perform a complete study of the dynamic and steady-state photoinduced processes of thick bacteriorhodopsin (bR) films, taking into account all the physical parameters and the coupling of rate equations with the energy transfer equation. The theoretical approach was compared with experimental data, and good concordance was found between both sets of data. The theoretical approach shows that the values of the rate constants for solid bR films are about two or three orders of magnitude lower than those observed in solution.

Holographic reflection gratings in photopolymerizable solgel materials.

The recording of holographic reflection gratings with a spatial frequency higher than 5400 lines/mm in photopolymerizable solgel materials is experimentally demonstrated. Diffraction efficiencies near 60% and a FWHM of 2.5 nm centered at 531.

Acrylamide-N,N'-methylenebisacrylamide silica glass holographic recording material.

In this paper, we describe a photopolymerizable silica glass based on acrylamide (AA) and N,N'-methylenebisacrylamide (BMA) as monomers, triethanolamine (TEA) as coinitiator and yellowish eosin (YE) as photoinitiator. We studied different compositions, analyzing the diffraction efficiency, energetic exposure and effective thickness obtained in the holographic gratings. A diffraction efficiency of 60 % with an energetic exposure of 139 mJ/cm(2) and an effective thickness of 1.

Purple membrane-polyacrilamide films as holographic recording materials.

The holographic parameters of purple membrane-polyacrylamide films obtained from a mutant form of Halobacterium salinarum (originally Halobacterium halobium) were measured. The synthesized films have an absorption of around 2.5 at 532 nm and a pH of 8.

Interkinetic nuclear movement may provide spatial clues to the regulation of neurogenesis.

During the transition from S phase to mitosis, vertebrate neuroepithelial cells displace their nuclei and subsequently migrate from the basal membrane to the apical surface of the neuroepithelium, a phenomenon termed interkinetic nuclear movement (INM). Here we provide evidence that cycling neuroepithelial cells pass through a neurogenic state in which they are situated apically, as defined by the capacity to express Notch1, Delta1, and Neurogenin2 (Ngn2). Based on this scenario, we have developed a mathematical model to analyze the influence of INM on neurogenesis.

Modelling complex populations formed by proliferating, quiescent and quasi-quiescent cells: application to plant root meristems.

A proliferating population of cells may be considered complex when its proliferative or growth fraction P is lower than 1 and/or when it is formed by subpopulations with different mean cycle times. The present paper shows that in such complex populations exponential growth is consistent with a steady-state distribution of cells. Obviously, when P=1 then cell distribution is only a function of cell age.

Learning and stabilization of altruistic behaviors in multi-agent systems by reciprocity.

Optimization of performance in collective systems often requires altruism. The emergence and stabilization of altruistic behaviors are difficult to achieve because the agents incur a cost when behaving altruistically. In this paper, we propose a biologically inspired strategy to learn stable altruistic behaviors in artificial multi-agent systems, namely reciprocal altruism.

Specialization in multi-agent systems through learning.

Specialization is a common feature in animal societies that leads to an improvement in the fitness of the team members and to an increase in the resources obtained by the team. In this paper we propose a simple reinforcement learning approach to specialization in an artificial multi-agent system. The system is composed of homogeneous and non-communicating agents.