Generalization of color by chickens: experimental observations and a Bayesian model

Sensory generalization influences animals' responses to novel stimuli. Because color forms a perceptual continuum, it is a good subject for studying generalization. Moreover, because different causes of variation in spectral signals, such as pigmentation, gloss, and illumination, have differing behavioral significance, it may be beneficial to have adaptable generalization. We report on generalization by poultry chicks following differential training to rewarded (T+) and unrewarded (T−) colors, in particular on the phenomenon of peak shift, which leads to subjects preferring stimuli displaced away from T−. The first three experiments test effects of learning either a fine or a coarse discrimination. In experiments 1 and 2, peak shift occurs, but contrary to some predictions, the shift is smaller after the animal learned a fine discrimination than after it learned a coarse discrimination. Experiment 3 finds a similar effect for generalization on a color axis orthogonal to that separating T+ from T−. Experiment 4 shows that generalization is rapidly modified by experience. These results imply that the scale of a “perceptual ruler” is set by experience. We show that the observations are consistent with generalization following principles of Bayesian inference, which forms a powerful framework for understanding this type of behavior

Variations on Kaluza-Klein Cosmology

We investigate the cosmological consequences of having quantum fields living in a space with compactified dimensions. We will show that the equation of state is not modified by topological effects and so the dynamics of the universe remains as it is in the infinite volume limit. On the contrary the thermal history of the universe depends on terms that are associated with having non-trivial topology. In the conclusions we discuss some issues about the relationship between the $c=1$ non-critical string-inspired cosmology and the result obtained with matter given by a hot massless field in S^{1}\times \mbox{\bf R}.Comment: 22 pages, 7 figures in a uuencoded file (using uufiles), LaTeX, FTUAM-93/13 (LaTeX errors corrected

Korea and the BICs (Brazil, India and China) : catching up experiences

This paper tests a neo-Schumpeterian model with industry-level data to analyze how Brazil, India, and China are catching up with South Korea’s technological frontier in a globalized world. The paper validates Aghion et al.’s inverted-U hypothesis that industries that are closer to the technological frontier innovate to escape competition while longer distances discourage innovating. It suggests that for effective catching up, distance-shortening (or innovation-enhancing) policies may be a necessary complement to liberalization. South Korea and China combined a variety of distance-shortening policies with financial subsidies to promote high tech industries and an export-led growth strategy. Post-liberalization, they leveraged swift competition to spur catch-up. In comparison, Brazil, which was as rich as South Korea, and India, which was as rich as China in 1980, are catching up more slowly. Import-substitution industrialization strategies saddled Brazil and India with a large anti-export bias, and unfocused attention to innovation-enhancing policies dampened global competitiveness. Post liberalization, many of their industries were too far behind the technological frontier to effectively benefit from competition. The catch-up experiences of Brazil, India, and China with South Korea illustrate that distance from the technological frontier matters and that the design of country-specific distance- shortening policies can be an important complement to trade liberalization in promoting catching up with richer countries.Labor Policies,Economic Theory&Research,Water and Industry,E-Business,Knowledge for Development

Effects of Liposomes Contained in Thermosensitive Hydrogels as Biomaterials Useful in Neural Tissue Engineering

Indexación: Scopus.Advances in the generation of suitable thermosensitive hydrogels for the delivery of cells in neural tissue engineering demonstrate a delicate relationship between physical properties and capabilities to promote cell proliferation and differentiation. To improve the properties of these materials, it is possible to add liposomes for the controlled release of bioactive elements, which in turn can affect the physical and biological properties of the hydrogels. In the present investigation, different hydrogels based on Pluronic F127 have been formulated with the incorporation of chitosan and two types of liposomes of two different sizes. The rheological and thermal properties and their relation with the neurite proliferation and growth of the PC12 cell line were evaluated. Our results show that the incorporation of liposomes modifies the properties of the hydrogels dependent on the concentration of chitosan and the lipid type in the liposomes, which directly affect the capabilities of the hydrogels to promote the viability and differentiation of PC12 cells. © 2017 by the authors.http://www.mdpi.com/1996-1944/10/10/112

Heralded photon amplification for quantum communication

Heralded noiseless amplification based on single-photon sources and linear optics is ideally suited for long-distance quantum communication tasks based on discrete variables. We experimentally demonstrate such an amplifier, operating at telecommunication wavelengths. Coherent amplification is performed with a gain of G=1.98+/-0.2, for a state with a maximum expected gain G=2. We also demonstrate that there is no need for a stable phase reference between the initial signal state and the local auxiliary photons used by the amplifier. These results highlight the potential of heralded quantum amplifiers for long-distance quantum communication, and bring device-independent quantum key distribution one step closer.Comment: 5 pages, 4 figure

Heat, Acid and Osmotic Stress Tolerance of Leuconostoc mesenteroides as Influenced by Prior Exposure to Various Mild Stress Conditions

The importance of Leuconostoc mesenteroides is recognized for its contribution to taste in cultured dairy products. It has been cited for its potential role as a probiotic. Consumer demand exists for new dairy products with health benefits. In the manufacture of probiotic-products survival of Leuconostoc mesenteroides would depend on its ability to tolerate challenging processing and storage conditions. Improved viability by prior exposure to mild stresses can increase stress tolerance toward a more severe stress. Furthermore, it can result in cross-protection due to connection of several proteins in response to stresses. Objective was to evaluate the effect of prior exposure to various mild stress conditions on the survival of Leuconostoc mesenteroides in challenging conditions. Leuconostoc mesenteroides spp. cremoris Vivolac Cremosa CIT/FPC Series cells were subjected to four mild stresses (acid, heat, ethanol and oxidative). Each mild stress had three levels of intensity; low, medium and high. Then culture was subjected to challenging acid, heat or osmotic conditions. MRS Agar was used for plating. Plates were incubated aerobically (30°C 48 h). The experiments were repeated three times with duplicate readings. Data were analyzed as a RBD using the Glimmix procedure and Tukey mean separation with a level of significance of 0.05. Heat tolerance of Leuconostoc mesenteroides at 60 °C was significantly enhanced by subjecting the bacteria to acid mild treatments of pH 5.0, 4.5 and 4.0 and heat mild treatments of 30, 35 and 45 °C (P\u3c0.05). Acid tolerance of Leuconostoc mesenteroides was not enhanced by application of any of the mild stresses studied when compared to their respective controls (P\u3e0.05). However good survivability was achieved with the application of the acid mild stress having cell counts ranging from 9.36 -8.77 log CFU/mL. Leuconostoc mesenteroides survivability was not affected with the exposure to osmotic challenge (P\u3e0.05). Furthermore, osmotic conditions promoted the growth Leuconostoc mesenteroides when compared to their initial cell counts (P\u3c0.05). The enhancement of its heat tolerance and the robustness displayed to the acid and osmotic challenging conditions has possible applications of Leuconostoc mesenteroides spp. cremoris in food products in which such challenging conditions are encountered

The Effect of Hay Supplementation on Performance of Grazing Alpaca in the Peruvian Andes

Productivity of alpaca grazing rangelands in the Andes is often limited by the low availability and quality of those pastures during the dry season of the year. The use as supplements of forages cultivated during the rainy season in appropriate areas in the Andes may be a strategy to improve performance of alpacas. Therefore, the supplementation of oat-vetch pellets or oat hay was evaluated and compared with a control group without supplementation. Sixty three female alpacas (15 months of age, 34 ± 1.0 kg BW), divided in three groups, grazing range pastures (6.1% crude protein and 61.3% NDF) during dry season in Puno region of the Peruvian Andes were used for the study. The supplement was offered daily after grazing (400 g/alpaca/day). The study lasted for 84 days with evaluations of weight gain and intake every 28 days. Weight gain was greater for animals supplemented with oat-vetch pellet (3.1 ± 0.27 kg) compared to oat hay (0.98 ± 0.33) (P≤ 0.05) while the control lost BW (0.64 ± 0.22). The total dry matter intake (pasture and supplement) was 502, 575.6 and 579.5 g / alpaca/ day for the control, oat-vetch pellet and oat hay group respectively indicating partial replacement of pasture by the supplement. Under the study conditions, the supplementation of oat-vetch pellets improved performance better than oats hay or no supplementation for alpacas grazing range pastures during the dry season