Time resolved pattern evolution in a large aperture laser

We have measured quasi-instantaneous transverse patterns in a broad aperture laser. Non-ordered patterns yielding to boundary determined regular structures in progressive time-integrated recording are observed. The linear analysis and numerical integration of the full Maxwell-Bloch equations allow us to interpret the features of the experiment. We show that this system being far from threshold cannot be fully understood with a perturbative model.Comment: 7 pages, 5 GIF figures . To be published in Phys. Rev. Let

Candle soot-based super-amphiphobic coatings resist protein adsorption

Super nonfouling surfaces resist protein adhesion and have a broad field of possible applications in implant technology, drug delivery, blood compatible materials, biosensors, and marine coatings. A promising route toward nonfouling surfaces involves liquid repelling architectures. The authors here show that soot-templated super-amphiphobic (SAP) surfaces prepared from fluorinated candle soot structures are super nonfouling. When exposed to bovine serum albumin or blood serum, x-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry analysis showed that less than 2 ng/cm(2) of protein was adsorbed onto the SAP surfaces. Since a broad variety of substrate shapes can be coated by soot-templated SAP surfaces, those are a promising route toward biocompatible materials design

Generation of nitrile groups on graphites in a nitrogen RF-plasma discharge

AbstractGraphite particles were treated in a nitrogen radio frequency-plasma (RF-plasma) at different excitation power. The morphological as well as chemical surface modifications were investigated by Raman spectroscopy, SEM, and XPS. Changes of the sp2/sp3 bonding ratio and selective surface terminations by functional groups were achieved. Especially, a direct functionalization of the graphites with nitrile groups was evidenced by a characteristic signal at 2240cm−1 in the Raman spectra after a high energy RF-nitrogen plasma treatment. A total nitrogen content of up to 11at.% was reached by the applied conditions. The increased polarity of the surfaces was confirmed by contact angle measurements. The nitrile functionalization may serve as synthetic scaffold for the development of new routes towards the chemical surface modification of carbon substrates. Furthermore, the modified graphites can be processed by common exfoliation techniques yielding nitrogen modified graphene nanoplatelets directly in polar and non-polar solvents

Effects of a bioactive olive pomace extract from Olea europaea on growth performance, gut function, and intestinal microbiota in broiler chickens

The present study aims to investigate the effects of supplementing broiler diets with a bioactive olive pomace extract (OE) from Olea europaea on growth performance, digestibility, gut microbiota, bile acid composition, and immune response. To this end, three hundred and six 1-day-old broiler chickens (Ross 308) were housed in floor pens (6 pens/treatment, with 17 birds/pen). Animals were fed with a standard non-medicated starter diet for 21 D, and from 22 to 42 D of age with their respective experimental diet: a negative control with no additives (Control), a positive control with 100 ppm of monensin (Monensin) and the basal diet supplemented with 750 ppm of an OE (Lucta S.A., Spain). Feed intake and growth rate were monitored weekly throughout the trial. From 21 to 42 D of age, no significant differences in feed intake were observed among dietary treatments; however, lower average daily gain and higher feed conversion ratio (P < 0.05) was observed in birds fed the Control compared to Monensin and OE groups. Performance of birds fed OE or Monensin was similar throughout the trial. The apparent ileal digestibility of crude protein was higher in birds fed Monensin than Control treatment (P < 0.05). No significant changes on bacterial composition at a family level were observed in the caeca of birds fed the experimental diets. Moreover, no significant differences on plasma and intestinal bile acid composition were observed among treatments. Birds fed the OE showed a significant decrease of IL-8 expression in the ileum (P < 0.05). Additionally, the expression of TGF-β4, and Bu-1 was significantly upregulated (P < 0.01) in broilers fed the OE and Monensin diets compared to those fed the Control. In conclusion, the inclusion of 750 ppm of a bioactive olive pomace extract from Olea europaea in broiler chicken diets improved animal growth likely as result of its anti-inflammatory properties

Plant species selection by free-ranging cattle in southern Bolivian tropical montane forests

The frequency of selection of functional groups and plant species by free-ranging cattle foraging in a diverse environment and its changes during the dry and the following prehumid seasons were investigated using direct observations and bite counting. The study was conducted at two sites in the Bolivian-Tucuman montane forests in southern Bolivia, by including datasets of a total of 16 animals. Across both study sites and the entire observation period (May to October/November), the cattle were found to select a broad spectrum of plant species from different functional groups. However, just a limited number of species made up a considerable contribution to overall plant selection. The functional group of the graminoids was selected most frequently, but their contribution to plant selection decreased significantly from 63.5% of total bites in May to 15.9% in September/October, in accordance with a decrease in availability. Selection of woody plants (shrubs and tree parts, the latter mainly in the form of leaf litter and fruits) increased with time, reaching its peak at the beginning of the prehumid season, while the herbs showed a curvilinear pattern of selection which was highest in August. Plant species belonging to the functional groups of ferns, climbers and epiphytes were also selected by the cattle, but generally at low relative proportions. Plant selection might be influenced by temporal differences in nutritional quality and availability of the preferred plant species and functional groups. Sampling behaviour seems to be the most likely reason for the inclusion of a broad range of plant species with overall low contribution to plant selectio

Quantifying human engagement into playful activities

Engaging in playful activities, such as playing a musical instrument, learning a language, or performing sports, is a fundamental aspect of human life. We present a quantitative empirical analysis of the engagement dynamics into playful activities. We do so by analyzing the behavior of millions of players of casual video games and discover a scaling law governing the engagement dynamics. This power-law behavior is indicative of a multiplicative (i.e., 'happy- get-happier') mechanism of engagement characterized by a set of critical exponents. We also find, depending on the critical exponents, that there is a phase transition between the standard case where all individuals eventually quit the activity and another phase where a finite fraction of individuals never abandon the activity. The behavior that we have uncovered in this work might not be restricted only to human interaction with videogames. Instead, we believe it reflects a more general and profound behavior of how humans become engaged in challenging activities with intrinsic rewards

Pflanzenselektion durch freilebende Rinder in südbolivianischen Bergwäldern

The aim of the present research was to study the plant species selected by freeranging cattle in southern Bolivian subtropical mountain forests. The cattle were followed from May to November 2005 during 4-5 days/month in two study sites. The number of bites on the different plant species were recorded every 6 min. during 1 min. of actual observation. Additionally, plant availability was measured. The selection and availability data were ranked, giving rank number 1 to the most frequently selected plant species. Basing on this ranking system, species were categorized into four categories. Overall, 447 plant species were found in the study sites, whereof 364 were observed to be selected by the cattle. A low number of species (15, including indetermined leaf litter) made up the major part of plant selection (about 60%) and were classified as “main forage plants”, with the grass Ichnanthus pallens being the most selected plant species. Sixteen species were classified as “preferred”, 20 as “least preferred” and 121 as “neutral”