Time filter

Source Type

Martinez-Garza C.,Autonomous University of the State of Morelos | Bongers F.,Wageningen University | Poorter L.,Wageningen University
Forest Ecology and Management

Functional traits may predict tree growth rates and survival in plantings aimed to accelerate natural succession in pastures. We evaluate the growth and survival of 24 tree species used for forest restoration in pastures in the wet tropics in Mexico for 42. months. We relate their performance to 13 underlying functional traits that are important for leaf display, tree architecture and reproduction. Pioneers realized both faster growth rates and higher survival than non-pioneer species. No consistent ontogenetic cross-overs in species growth and survival were found during 42. months, which implies that species performance early after planting (12. months) predicted performance well after 42. months, probably because environmental conditions changed little over time in these early-successional pastures. Nine out of 12 functional traits were good predictors of growth rates and/or survival measures across all 24 species or for pioneer or non-pioneer species separately. Growth rates and survival were positively related to crown size and negatively to seed mass, but they were - surprisingly - not related to the leaf traits we measured. Multivariate plant trait axes explained species growth rates and survival better than individual traits only for the non-pioneer species group. Selection of additional traits may be needed for better predictions of overall performance of restoration plantings. Combining the basic science of functional ecology with the applied goals of forest management and restoration allow us to select the best mid-term performing tree species for planting in pastures using a short-term screening of growth and survival rates. Pioneers and non-pioneer species with small seeds and large crown length are good candidates for plantings in pastures since they have the best mid-term performance. © 2013 Elsevier B.V. Source

Martinez S.S.,Autonomous University of the State of Morelos | Uribe E.V.,Autonomous University of Mexico State
Ultrasonics Sonochemistry

The degradation of azure B dye (C15H16ClN 3S; AB) has been studied by Fenton, sonolysis and sono-electroFenton processes employing ultrasound at 23 kHz and the electrogeneration of H 2O2 at the reticulated vitreous carbon electrode. It was found that the dye degradation followed apparent first-order kinetics in all the degradation processes tested. The rate constant was affected by both the pH of the solution and initial concentration of Fe2+, with the highest degradation obtained at pH between 2.6 and 3. The first-order rate constant decreased in the following order: sono-electroFenton > Fenton > sonolysis. The rate constant for AB degradation by sono-electroFenton is ∼10-fold that of sonolysis and ∼2-fold the one obtained by Fenton under silent conditions. The chemical oxygen demand was abated ∼68% and ∼85% by Fenton and sono-electroFenton respectively, achieving AB concentration removal over 90% with both processes. © 2011 Elsevier B.V. All rights reserved. Source

Le Corre M.,Autonomous University of the State of Morelos
British Journal of Developmental Psychology

Many have proposed that the acquisition of the cardinal principle (CP) is a result of the discovery of the numerical significance of the order of the number words in the count list. However, this need not be the case. Indeed, the CP does not state anything about the numerical significance of the order of the number words. It only states that the last word of a correct count denotes the numerosity of the counted set. Here, we test whether the acquisition of the CP involves the discovery of the later-greater principle - that is, that the order of the number words corresponds to the relative size of the numerosities they denote. Specifically, we tested knowledge of verbal numerical comparisons (e.g., Is 'ten' more than 'six'?) in children who had recently learned the CP. We find that these children can compare number words between 'six' and 'ten' only if they have mapped them onto non-verbal representations of numerosity. We suggest that this means that the acquisition of the CP does not involve the discovery of the correspondence between the order of the number words and the relative size of the numerosities they denote. © 2013 The British Psychological Society. Source

Butler M.,University of Manitoba | Meneses-Acosta A.,Autonomous University of the State of Morelos
Applied Microbiology and Biotechnology

The demand for production of glycoproteins from mammalian cell culture continues with an increased number of approvals as biopharmaceuticals for the treatment of unmet medical needs. This is particularly the case for humanized monoclonal antibodies which are the largest and fastest growing class of therapeutic pharmaceuticals. This demand has fostered efforts to improve the efficiency of production as well as to address the quality of the final product. Chinese hamster ovary cells are the predominant hosts for stable transfection and high efficiency production on a large scale. Specific productivity of recombinant glycoproteins from these cells can be expected to be above 50 pg/cell/day giving rise to culture systems with titers of around 5 g/L if appropriate fed-batch systems are employed. Cell engineering can delay the onset of programmed cell death to ensure prolonged maintenance of productive viable cells. The clinical efficacy and quality of the final product can be improved by strategic metabolic engineering. The best example of this is the targeted production of afucosylated antibodies with enhanced antibody-dependent cell cytotoxicity, an important function for use in cancer therapies. The development of culture media from non-animal sources continues and is important to ensure products of consistent quality and without the potential danger of contamination. Process efficiencies may also be improved by employing disposable bioreactors with the associated minimization of downtime. Finally, advances in downstream processing are needed to handle the increased supply of product from the bioreactor but maintaining the high purity demanded of these biopharmaceuticals. © Springer-Verlag Berlin Heidelberg 2012. Source

Diaz J.,Autonomous University of the State of Morelos
Plant Signaling and Behavior

Systems biology and mathematical approaches are required for understanding how genetic regulatory networks process information from the environment. a typical genetic communication channel is conformed by: (1) an encoder, which is a specific membrane receptor that perceives the environmental information in the form of a concentration of a specific phytohormone. in the particular case of the ethylene signaling pathway, the encoder is the Etr1,2 specific receptor to ethylene; (2) a transmitting pathway, which is a signaling pathway. in the case, the ethylene signaling pathway; (3) a decoder, which is the molecular transcriptional machinery associated with the ERF1 and downstream genes and (4) an effector, which is the molecular translational machinery associated to the ethylene genetic network. Every communication channel is subject to noise, i.e., any physicochemical process that can alter the message carried from the encoder to the decoder and effector. noise introduces a certain amount of uncertainty in any message spread through the communication channel. the amount of uncertainty in the content of a message is measured with the Shannon's entropy function H and, consequently, the amount of information actually carried by the message can be measured with the information function I = Hmax - H. Genetic networks are composed of a relative low and fluctuating maxamount of molecules and this characteristic, together with the effect of noise, produces a genetic response at time t with a probability p(t) of being correct with respect to the input message, and a probability 1 - p(t) of been incorrect. From these probability values, H and I functions can be evaluated and, for the first time, it is possible to assign a measure of information content to each message associated to a given concentration of phytohormone. This type of analysis can be applied to any other plant genetic regulatory network. © 2011 Landes Bioscience. Source

Discover hidden collaborations