Primordial Black Holes: sirens of the early Universe

Primordial Black Holes (PBHs) are, typically light, black holes which can form in the early Universe. There are a number of formation mechanisms, including the collapse of large density perturbations, cosmic string loops and bubble collisions. The number of PBHs formed is tightly constrained by the consequences of their evaporation and their lensing and dynamical effects. Therefore PBHs are a powerful probe of the physics of the early Universe, in particular models of inflation. They are also a potential cold dark matter candidate.Comment: 21 pages. To be published in "Quantum Aspects of Black Holes", ed. X. Calmet (Springer, 2014

Molecular Mechanism of a Green-Shifted, pH-Dependent Red Fluorescent Protein mKate Variant

Fluorescent proteins that can switch between distinct colors have contributed significantly to modern biomedical imaging technologies and molecular cell biology. Here we report the identification and biochemical analysis of a green-shifted red fluorescent protein variant GmKate, produced by the introduction of two mutations into mKate. Although the mutations decrease the overall brightness of the protein, GmKate is subject to pH-dependent, reversible green-to-red color conversion. At physiological pH, GmKate absorbs blue light (445 nm) and emits green fluorescence (525 nm). At pH above 9.0, GmKate absorbs 598 nm light and emits 646 nm, far-red fluorescence, similar to its sequence homolog mNeptune. Based on optical spectra and crystal structures of GmKate in its green and red states, the reversible color transition is attributed to the different protonation states of the cis-chromophore, an interpretation that was confirmed by quantum chemical calculations. Crystal structures reveal potential hydrogen bond networks around the chromophore that may facilitate the protonation switch, and indicate a molecular basis for the unusual bathochromic shift observed at high pH. This study provides mechanistic insights into the color tuning of mKate variants, which may aid the development of green-to-red color-convertible fluorescent sensors, and suggests GmKate as a prototype of genetically encoded pH sensors for biological studies

Effects of Trophic Skewing of Species Richness on Ecosystem Functioning in a Diverse Marine Community

Widespread overharvesting of top consumers of the world’s ecosystems has “skewed” food webs, in terms of biomass and species richness, towards a generally greater domination at lower trophic levels. This skewing is exacerbated in locations where exotic species are predominantly low-trophic level consumers such as benthic macrophytes, detritivores, and filter feeders. However, in some systems where numerous exotic predators have been added, sometimes purposefully as in many freshwater systems, food webs are skewed in the opposite direction toward consumer dominance. Little is known about how such modifications to food web topology, e.g., changes in the ratio of predator to prey species richness, affect ecosystem functioning. We experimentally measured the effects of trophic skew on production in an estuarine food web by manipulating ratios of species richness across three trophic levels in experimental mesocosms. After 24 days, increasing macroalgal richness promoted both plant biomass and grazer abundance, although the positive effect on plant biomass disappeared in the presence of grazers. The strongest trophic cascade on the experimentally stocked macroalgae emerged in communities with a greater ratio of prey to predator richness (bottom-rich food webs), while stronger cascades on the accumulation of naturally colonizing algae (primarily microalgae with some early successional macroalgae that recruited and grew in the mesocosms) generally emerged in communities with greater predator to prey richness (the more top-rich food webs). These results suggest that trophic skewing of species richness and overall changes in food web topology can influence marine community structure and food web dynamics in complex ways, emphasizing the need for multitrophic approaches to understand the consequences of marine extinctions and invasions

General destabilizing effects of eutrophication on grassland productivity at multiple spatial scales

Eutrophication is a widespread environmental change that usually reduces the stabilizing effect of plant diversity on productivity in local communities. Whether this effect is scale dependent remains to be elucidated. Here, we determine the relationship between plant diversity and temporal stability of productivity for 243 plant communities from 42 grasslands across the globe and quantify the effect of chronic fertilization on these relationships. Unfertilized local communities with more plant species exhibit greater asynchronous dynamics among species in response to natural environmental fluctuations, resulting in greater local stability (alpha stability). Moreover, neighborhood communities that have greater spatial variation in plant species composition within sites (higher beta diversity) have greater spatial asynchrony of productivity among communities, resulting in greater stability at the larger scale (gamma stability). Importantly, fertilization consistently weakens the contribution of plant diversity to both of these stabilizing mechanisms, thus diminishing the positive effect of biodiversity on stability at differing spatial scales. Our findings suggest that preserving grassland functional stability requires conservation of plant diversity within and among ecological communities

Effect of Ultrasonic-Assisted Blanching on Size Variation, Heat Transfer, and Quality Parameters of Mushrooms

The main aim of this work was to assess the influence of the application of power ultrasound during blanching of mushrooms (60 90 °C) on the shrinkage, heat transfer, and quality parameters. Kinetics of mushroom shrinkage was modeled and coupled to a heat transfer model for conventional (CB) and ultrasonic-assisted blanching (UB). Cooking value and the integrated residual enzymatic activity were obtained through predicted temperatures and related to the hardness and color variations of mushrooms, respectively. The application of ultrasound led to an increase of shrinkage and heat transfer rates, being this increase more intense at low process temperatures. Consequently, processing time was decreased (30.7 46.0 %) and a reduction in hardness (25.2 40.8 %) and lightness (13.8 16.8 %) losses were obtained. The best retention of hardness was obtained by the UB at 60 °C, while to maintain the lightness it was the CB and UB at 90 °C. For enhancing both quality parameters simultaneously, a combined treatment (CT), which consisted of a CB 0.5 min at 90 °C and then an UB 19.9min at 60 °C, was designed. In this manner, compared with the conventional treatment at 60 °C, reductions of 39.1, 27.2, and 65.5 % for the process time, hardness and lightness losses were achieved, respectively. These results suggest that the CT could be considered as an interesting alternative to CB in order to reduce the processing time and improve the overall quality of blanched mushrooms.The authors acknowledge the financial support of Consejo Nacional de Investigaciones Cientificas y Tecnicas and Universidad Nacional de La Plata from Argentina, Erasmus Mundus Action 2-Strand 1 and EuroTango II Researcher Training Program and Ministerio de Economia y Competitividad (SPAIN) and the FEDER (project DPI2012-37466-CO3-03).Lespinard, A.; Bon Corbín, J.; Cárcel Carrión, JA.; Benedito Fort, JJ.; Mascheroni, RH. (2015). Effect of Ultrasonic-Assisted Blanching on Size Variation, Heat Transfer, and Quality Parameters of Mushrooms. Food and Bioprocess Technology. 8(1):41-53. https://doi.org/10.1007/s11947-014-1373-zS415381Aguirre, L., Frias, J. M., Barry-Ryan, C., & Grogan, H. (2009). Modelling browning and brown spotting of mushrooms (Agaricus bisporus) stored in controlled environmental conditions using image analysis. Journal of Food Engineering, 91, 280–286.Anantheswaran, R. C., Sastry, S. K., Beelman, R. B., Okereke, A., & Konanayakam, M. (1986). Effect of processing on yield, color, and texture of canned mushrooms. Journal of Food Science, 51(5), 1197–1200.Biekman, E. S. A., Kroese-Hoedeman, H. I., & Schijvens, E. P. H. M. (1996). Loss of solutes during blanching of mushrooms (Agaricus bisporus) as a result of shrinkage and extraction. Journal of Food Engineering, 28(2), 139–152.Biekman, E. S. A., van Remmen, H. H. J., Kroese-Hoedeman, H. I., Ogink, J. J. M., & Schijvens, E. P. H. M. (1997). Effect of shrinkage on the temperature increase in evacuated mushrooms (Agaricus bisporus) during blanching. Journal of Food Engineering, 33(1–2), 87–99.Brennan, M., Le Port, G., & Gormley, R. (2000). Post-harvest treatment with citric acid or hydrogen peroxide to extend the shelf life of fresh sliced mushrooms. Lebensmittel Wissenschaft und Technologie, 33, 285–289.Cárcel, J. A., Benedito, J., Rosselló, C., & Mulet, A. (2007). Influence of ultrasound intensity on mass transfer in apple immersed in a sucrose solution. Journal of Food Engineering, 78, 472–479.Cárcel, J. A., Benedito, J., Bon, J., & Mulet, A. (2007). High intensity ultrasound effects on meat brining. Meat Science, 76, 611–619.Cárcel, J. A., García-Pérez, J. V., Benedito, J., & Mulet, A. (2011). Food process innovation through new technologies: Use of ultrasound. Journal of Food Engineering, 110, 200–207.Cheng, X., Zhang, M., & Adhikari, B. (2013). The inactivation kinetics of polyphenol oxidase in mushroom (Agaricus bisporus) during thermal and thermosonic treatmemts. Ultrasonics Sonochemistry, 20, 674–679.Cliffe-Byrnes, V., & O’Beirne, D. (2007). Effects of gas atmosphere and temperature on the respiration rates of whole and sliced mushrooms (Agaricus bisporus): implications for film permeability in modified atmosphere packages. Journal of Food Science, 72, 197–204.Coskuner, Y., & Ozdemir, Y. (1997). Effects of canning processes on the elements content of cultivated mushrooms (Agaricus bisporus). Food Chemistry, 60(4), 559–562.Cruz, R. M. S., Vieira, M. C., Fonseca, S. C., & Silva, C. L. M. (2011). Impact of thermal blanching and thermosonication treatments on watercress (Nasturtium officinale) quality: thermosonication process optimisation and microstructure evaluation. Food and Bioprocess Technology, 4(7), 1197–1204.De Gennaro, L., Cavella, S., Romano, R., & Masi, P. (1999). The use of ultrasound in food technology I: inactivation of peroxidase by thermosonication. Journal of Food Engineering, 39, 401–407.De la Fuente, S., Riera, E., Acosta, V. M., Blanco, A., & Gallego-Juárez, J. A. (2006). Food drying process by power ultrasound. Ultrasonics, 44, 523–527.Delgado, A. E., Zheng, L., & Sun, D. W. (2009). Influence of ultrasound on freezing rate of immersion-frozen apples. Food and Bioprocess Technology, 2, 263–270.Devece, C., Rodríguez-López, J. N., Fenoll, J. T., Catalá, J. M., De los Reyes, E., & García-Cánovas, F. (1999). Enzyme inactivation analysis for industrial blanching applications: comparison of microwave, conventional, and combination heat treatments on mushroom polyphenoloxidase activity. Journal of Agricultural and Food Chemistry, 47(11), 4506–4511.Fernandes, F. A. N., & Rodrigues, S. (2007). Ultrasound as pre-treatment for drying of fruits: dehydration of banana. Journal of Food Engineering, 82, 261–267.Gabaldón-Leyva, C. A., Quintero-Ramos, A., Barnard, J., Balandrán-Quintana, R. R., Talamás-Abbud, R., & Jiménez-Castro, J. (2007). Effect of ultrasound on the mass transfer and physical changes in brine bell pepper at different temperatures. Journal of Food Engineering, 81, 374–379.Gallego-Juárez, J. A., Riera, E., De la Fuente, S., Rodríguez-Corral, G., Acosta-Aparicio, V. M., & Blanco, A. (2007). Application of high-power ultrasound for dehydration of vegetables: processes and devices. Drying Technology, 25, 1893–1901.Gamboa-Santos, J., Montilla, A., Soria, A. C., & Villamiel, M. (2012). Effects of conventional and ultrasound blanching on enzyme inactivation and carbohydrate content of carrots. European Food Research and Technology, 234, 1071–1079.García-Pérez, J. V., Cárcel, J. A., De la Fuente, S., & Riera, E. (2006). Ultrasonic drying of foodstuff in a fluidized bed. Parametric study. Ultrasonics, 44, 539–543.García-Pérez, J. V., Cárcel, J. A., Riera, E., Rosselló, C., & Mulet, A. (2012). Intensification of low-temperature drying by using ultrasound. Drying Technology, 30, 1199–1208.Gonzáles-Fandos, E., Giménez, M., Olarte, C., Sanz, S., & Simón, A. (2000). Effect of packaging conditions on the growth of microorganisms and the quality characteristics of fresh mushrooms (Agaricus bisporus) stored at inadequate temperatures. Journal of Applied Microbiology, 89, 624–632.Gormley, T. R. (1975). Chill storage of mushrooms. Journal of the Science of Food and Agriculture, 26, 401–411.Gouzi, H., Depagne, C., & Coradin, T. (2012). Kinetics and thermodynamics of thermal inactivation of polyfenol oxidase in an aqueous extract from Agaricus bisporus. Journal of Agricultural and Food Chemistry, 60, 500–506.Holdsworth, S. D. (1997). Thermal processing of packaged foods. London: Chapman Hall.Horžić, D., Jambrak, A. R., Belščak-Cvitanović, A., Komes, D., & Lelas, V. (2012). Comparison of conventional and ultrasound assisted extraction techniques of yellow tea and bioactive composition of obtained extracts. Food and Bioprocess Technology, 5, 2858–2870.Jambrak, A. R., Mason, T. J., Paniwnyk, L., & Lelas, V. (2007a). Ultrasonic effect on pH, electric conductivity, and tissue surface of button mushrooms, brussels sprouts and cauliflower. Czech Journal of Food Science, 25, 90–99.Jambrak, A. R., Mason, T. J., Paniwnyk, L., & Lelas, V. (2007b). Accelerated drying of button mushrooms, Brussels sprouts and cauliflower by applying power ultrasound and its rehydration properties. Journal of Food Engineering, 81, 88–97.Jasinski, E. M., Stemberger, B., Walsh, R., & Kilara, A. (1984). Ultra structural studies of raw and processed tissue of the major cultivated mushroom, Agaricus bisporus. Food Microstructure, 3, 191–196.Jolivet, S., Arpin, N., Wicher, H. J., & Pellon, G. (1998). Agaricus bisporus browning: a review. Mycological Research, 102, 1459–1483.Konanayakam, M., & Sastry, S. K. (1988). Kinetics of shrinkage of mushroom during blanching. Journal of Food Science, 53(5), 1406–1411.Kotwaliwale, N., Bakane, P., & Verma, A. (2007). Changes in textural and optical properties of oyster mushroom during hot air drying. Journal of Food Engineering, 78(4), 1207–1211.Leadley C. & Williams A. (2002). Power ultrasound—current and potential applications for food processing, Review No 32, Campden and Chorleywood Food Research Association.Lespinard, A. R., Goñi, S. M., Salgado, P. R., & Mascheroni, R. H. (2009). Experimental determination and modeling of size variation, heat transfer and quality indexes during mushroom blanching. Journal of Food Engineering, 92, 8–17.Lima, M., & Sastry, S. K. (1990). Influence of fluid rheological properties and particle location on ultrasound-assisted heat transfer between liquid and particles. Journal of Food Science, 55(4), 1112–1115.López, P., & Burgos, J. (1995). Peroxidase stability and reactivation after heat treatment and manothermosonication. Journal of Food Science, 60(3), 551–553.López, P., Sala, F. J., Fuente, J. L., Cardon, S., Raso, J., & Burgos, J. (1994). Inactivation of peroxidase lipoxigenase and phenol oxidase by manothermosonication. Journal of Agricultural and Food Chemistry, 42(2), 253–256.Mansfield, T. (1962). High temperature-short time sterilization. Proceedings First International Congress on Food Science and Technology, 4, 311–316.Mason T. J. (1998). Power ultrasound in food processing—the way forward. In M. J. W. Povey & T. J. Mason (Eds.), Ultrasound in Food Processing (pp 103–126). Blackie Academic & Professional, London.McArdle F. J. & Curwen D. (1962). Some factors influencing shrinkage of canned mushrooms. Mushroom Science, 5, 547–557.McArdle, F. J., Kuhn, G. D., & Beelman, R. B. (1974). Influence of vacuum soaking on yield and quality of canned mushrooms. Journal of Food Science, 39, 1026–1028.Mohapatra, D., Bira, Z. M., Kerry, J. P., Frías, J. M., & Rodrigues, F. A. (2010). Postharvest hardness and color evolution of White button mushrooms (Agaricus bisporus). Journal of Food Science, 75(3), 146–152.Ohlsson, T. (1980). Temperature dependence of sensory quality changes during thermal processing. Journal of Food Science, 45(4), 836–847.Ortuño, C., Martínez-Pastor, M., Mulet, A., & Benedito, J. (2013). Application of high power ultrasound in the supercritical carbon dioxide inactivation of Saccharomyces cerevisiae. Food Research International, 51, 474–481.Peralta-Jimenez, L., & Cañizares-Macías, M. P. (2012). Ultrasound-assisted method for extraction of theobromine and caffeine from cacao seeds and chocolate products. Food and Bioprocess Technology, 6, 3522–3529.Rodríguez-López, J. N., Fenoll, N. G., Tudela, J., Devece, C., Sánchez-Hernández, D., De los Reyes, D., et al. (1999). Thermal inactivation of mushroom polyphenoloxidase employing 2450 MHz microwave radiation. Journal of Agricultural Food Chemistry, 47, 3028–3035.Sala, F., Burgos, J., Condon, S., Lopez, P., & Raso, J. (1995). Effect of heat and ultrasound on microorganisms and enzymes. In G. W. Gould (Ed.), New methods of food preservation (1st ed., pp. 176–204). Glasgow: Blackie Academic and professional.Sanjuán, N., Hernando, I., Lluch, M. A., & Mullet, A. (2005). Effects of low temperature blanching on texture, microstructure and rehydration capacity of carrots. Journal of the Science of Food and Agriculture, 85, 2071–2076.Santos, M. V., & Lespinard, A. R. (2011). Numerical simulation of mushrooms during freezing using the FEM and an enthalpy—Kirchhoff formulation. Heat and Mass Transfer, 47, 1671–1683.Sastry, S. K., Beelman, R. B., & Speroni, J. J. (1985). A three-dimensional finite element model for thermally induced changes in foods: application to degradation of agaritine in canned mushrooms. Journal of Food Science, 50(5), 1293–1299.Sastry, S. K., Shen, G. Q., & Blaisdel, J. L. (1989). Effect of ultrasonic vibration on fluid-to-particule convective heat transfer coefficients. Journal of Food Science, 54(1), 229–230.Sensoy, I., & Sastry, S. K. (2004). Ohmic blanching of mushrooms. Journal of Food Process Engineering, 27(1), 1–15.Sheen, S., & Hayakawa, K. (1991). Finite difference simulation for heat conduction with phase change in an irregular food domain with volumetric change. International Journal of Heat and Mass Transfer, 34(6), 1337–1346.Simal, S., Benedito, J., Sanchez, E. S., & Rossello, C. (1998). Use of ultrasound to increase mass transport rates during osmotic dehydration. Journal of Food Engineering, 36, 323–336.Siró, I., Vén, C., Balla, C., Jónás, G., Zeke, I., & Friedrich, L. (2009). Application of an ultrasonic assisted curing technique for improving the diffusion of sodium chloride in porcine meat. Journal of Food Engineering, 91, 353–362.Soria, A. C., & Villamiel, M. (2010). Effect of ultrasound on the technological properties and bioactivity in foods: a review. Trends in Food Science and Technology, 21, 323–331.Verlinden, B. E., Yuksel, D., Baheri, M., De Baerdemaeker, J., & Van Dijk, C. (2000). Low temperature blanching effect on the changes in mechanical properties during subsequent cooking of three potato cultivars. International Journal of Food Science and Technology, 35, 331–340.Wu, C. M., Wu, J. L.-P., Chen, C.-C., & Chou, C.-C. (1981). Flavor recovery from mushroom blanching water. In G. Charalambous & G. Inglett (Eds.), The quality of foods and beverages: chemistry and technology, vol. 1. New York: Academic Press.Zivanovic, S., & Buescher, R. (2004). Changes in mushroom texture and cell wall composition affected by thermal processing. Journal of Food Science, 69, 44–48

Social preferences and network structure in a population of reef manta rays

Understanding how individual behavior shapes the structure and ecology ofpopulations is key to species conservation and management. Like manyelasmobranchs, manta rays are highly mobile and wide ranging species threatened byanthropogenic impacts. In shallow-water environments these pelagic rays often formgroups, and perform several apparently socially-mediated behaviors. Group structuresmay result from active choices of individual rays to interact, or passive processes.Social behavior is known to affect spatial ecology in other elasmobranchs, but this isthe first study providing quantitative evidence for structured social relationships inmanta rays. To construct social networks, we collected data from more than 500groups of reef manta rays over five years, in the Raja Ampat Regency of West Papua.We used generalized affiliation indices to isolate social preferences from non-socialassociations, the first study on elasmobranchs to use this method. Longer lastingsocial preferences were detected mostly between female rays. We detectedassortment of social relations by phenotype and variation in social strategies, with theoverall social network divided into two main communities. Overall network structurewas characteristic of a dynamic fission-fusion society, with differentiated relationshipslinked to strong fidelity to cleaning station sites. Our results suggest that fine-scaleconservation measures will be useful in protecting social groups of M. alfredi in theirnatural habitats, and that a more complete understanding of the social nature of mantarays will help predict population response