Global continuation of monotone wavefronts

In this paper, we answer the question about the criteria of existence of monotone travelling fronts $u = \phi(\nu \cdot x+ct), \phi(-\infty) =0, \phi(+\infty) = \kappa,$ for the monostable (and, in general, non-quasi-monotone) delayed reaction-diffusion equations $u_t(t,x) - \Delta u(t,x) = f(u(t,x), u(t-h,x)).$ $C^{1,\gamma}$-smooth $f$ is supposed to satisfy $f(0,0) = f(\kappa,\kappa) =0$ together with other monostability restrictions. Our theory covers the two most important cases: Mackey-Glass type diffusive equations and KPP-Fisher type equations. The proofs are based on a variant of Hale-Lin functional-analytic approach to the heteroclinic solutions where Lyapunov-Schmidt reduction is realized in a `mobile' weighted space of $C^2$-smooth functions. This method requires a detailed analysis of a family of associated linear differential Fredholm operators: at this stage, the discrete Lyapunov functionals by Mallet-Paret and Sell are used in an essential way.Comment: 21 pages, 3 figures, submitte

Industrial cluster governance in a developing country context: evidence from the petrochemical sector in the Mexican state of Veracruz

This thesis combines analysis of the political economy of Mexico with the global value chain approach to study the trajectory of the development of the Veracruz cluster and the governance structure of vertical inter-firm relationships in the locality. The petrochemical cluster located in the state of Veracruz is formed by a pool of state-owned and local private companies and is arguably the largest agglomeration of industrial firms in southern Mexico. These firms are linked to one another through output-input relationships. State-owned petrochemical complexes, which are part of Petróleos Mexicanos (PEMEX), Mexico's oil and natural gas company, supply industrial raw materials that local private firms use to process intermediate petrochemical inputs. Empirical evidence demonstrates that state-owned firms exercise a disproportionate degree of authority over input transactions. The latter assertion is illustrated by the fact that PEMEX-Petrochemicals is the only domestic producer (and therefore supplier) of a large number of inputs demanded in the locality. This, along with the hazardous nature of petrochemical inputs and spatial proximity, has contributed to locking local firms into captive transactional relationships. The significance of studying the Veracruz cluster and the nature of inter-firm transactional relationships lies in the fact that both are heavily influenced by drivers inherent in the development path the country has followed in past decades, which is characterised in the first place by the adoption of import-substituting industrialisation (ISI) policies in the 1960s and 1970s and later by the implementation of market-orientated policies in the 1980s and beyond. The discussion is therefore situated in a much broader empirical setting that pays considerable attention to economic, political, and institutional factors. For instance, external determinants such as the extent of state intervention in economic planning in the 1960s and 1970s, the economic liberalisation process embarked on by Mexico in the 1980s and 1990s, the institutionalisation of sectoral regulatory policies, the reliance of the government on PEMEX revenues, and the implications of the North American Free Trade Agreement (NAFTA), among others, will help us understand the trajectory of the petrochemical industry and the governance of inter-firm transactional linkages in southern Veracruz

Molecular Mechanisms Underlying Environmental Enrichment-Induced Neuroprotection in Vulnerability to Nicotine Addiction

Tobacco use is the number one preventable cause of death in the world. Nicotine is the principal, addictive component in tobacco responsible for its reinforcing properties that drive the behavioral manifestations of nicotine addiction. Environment is becoming increasingly implicated in nicotine susceptibility. However, the molecular mechanisms that underlie susceptibility to nicotine addiction remain unknown. An ideal animal model that addresses environmental factors uses rats raised in an enriched condition (EC), a standard condition (SC), and an impoverished condition (IC); which differ in novelty, social cohorts, handling, and physical activity. EC rats exhibit a neuroprotective-like phenotype in the behavioral resistance to drugs of abuse; however, the impact of enrichment on nicotine-mediated behaviors and the subsequent molecular mechanisms underlying these behavioral adaptations remain unidentified. EC rats were found to have increased behavioral sensitization, an indirect measure of drug-mediated motivation, in response to repeated experimenter-delivered nicotine in comparison to IC and SC rats. Additionally, EC rats have decreased nicotine-maintained responding compared to IC rats in a self-administration paradigm, the most reliable experimental model to evaluate the reinforcing properties of drugs of abuse. One commonality we observed in both behavioral paradigms was that phosphorylated extracellular signal-regulated kinase1/2 (pERK1/2), an intracellular signaling protein kinase involved in drug-induced neuroplasticity, levels in the prefrontal cortex (PFC) were significantly increased in response to nicotine in IC rats, whereas nicotine-mediated increases in pERK1/2 activity were attenuated in EC rats. MicroRNAs (miRs) are post-transcriptional regulators of gene expression that have recently been implicated in drug-mediated neuroadaptations. MiR-221 was found to be highly enriched strictly in the PFC of EC rats in response to repeated nicotine administration. Lentiviral overexpression of miR-221 in the PFC of IC rats enhanced nicotine-mediated locomotor sensitivity while attenuating nicotine-mediated increases in pERK1/2 activity. However, enrichment-induced decreases in nicotine-intake were associated with an attenuation in nicotine-mediated orexin receptor-1 (OX1R) upregulation within the PFC. Additionally, although not as robustly as in the repeated model of repeated nicotine administration, miR-221 was increased significantly within the PFC of EC rats that underwent nicotine self-administration. Collectively, these studies implicate miR-221-dependent regulation of ERK1/2 within the PFC in response to nicotine in mediating the increased behavioral sensitivity observed in EC rats, as well as an OXR1-dependent regulation of ERK1/2 within the PFC in decreasing nicotine-intake in EC rats. Moreover, these studies suggest that miR-221 may be a universal mediator of the enrichment-induced protective-like phenotype in response to nicotine exposure. Future studies examining the upstream and downstream mechanisms in which miR-221 is mediating its effects will better clarify the exact mechanism of miR-221 and lead to potential therapeutic targets for nicotine addiction

Evolving supernova remnants in multiphase interstellar media

We performed three-dimensional magnetohydrodynamic simulations to study the evolution of a supernova remnant (SNR) in a turbulent neutral atomic interstellar medium. The media used as background shares characteristics with the Solar neighbourhood and the SNR has mass and energy similar to those of a Type Ia object. Our initial conditions consist of dense clouds in a diluted medium, with the main difference between simulations being the average magnitude of the magnetic field. We measured amplifications of the magnetic energy of up to 34 per cent, and we generated synthetic maps that illustrate how the same object can show different apparent geometries and physical properties when observed through different lines of sight.Fil: Villagran Azuara, Marco Adrian. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Velazquez, Paula Florencia. Universidad Nacional Autónoma de México; MéxicoFil: Gomez, Daniel Osvaldo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Giacani, Elsa Beatriz. Universidad de Buenos Aires. Facultad de Arquitectura, Diseño y Urbanismo; Argentina. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin

Inverting angiogenesis with interstitial flow and chemokine matrix-binding affinity

The molecular signaling pathways that orchestrate angiogenesis have been widely studied, but the role of biophysical cues has received less attention. Interstitial flow is unavoidable in vivo, and has been shown to dramatically change the neovascular patterns, but the mechanisms by which flow regulates angiogenesis remain poorly understood. Here, we study the complex interactions between interstitial flow and the affinity for matrix binding of different chemokine isoforms. Using a computational model, we find that changing the matrix affinity of the chemokine isoform can invert the effect of interstitial flow on angiogenesis—from preferential growth in the direction of the flow when the chemokine is initially matrix-bound to preferential flow against the flow when it is unbound. Although fluid forces signal endothelial cells directly, our data suggests a mechanism for the inversion based on biotransport arguments only, and offers a potential explanation for experimental results in which interstitial flow produced preferential vessel growth with and against the flow. Our results point to a particularly intricate effect of interstitial flow on angiogenesis in the tumor microenvironment, where the vessel network geometry and the interstitial flow patterns are complex.Peer ReviewedPostprint (published version

Social Equity Matters in Payments for Ecosystem Services

Although conservation efforts have sometimes succeeded in meeting environmental goals at the expense of equity considerations, the changing context of conservation and a growing body of evidence increasingly suggest that equity considerations should be integrated into conservation planning and implementation. However, this approach is often perceived to be at odds with the prevailing focus on economic efficiency that characterizes many payment for ecosystem services (PES) schemes. Drawing from examples across the literature, we show how the equity impacts of PES can create positive and negative feedbacks that influence ecological outcomes. We caution against equity-blind PES, which overlooks these relationships as a result of a primary and narrow focus on economic efficiency. We call for further analysis and better engagement between the social and ecological science communities to understand the relationships and trade-offs among efficiency, equity, and ecological outcomes

Cohort Differences in Personal Goals and Life Satisfaction in Young Adulthood: Evidence for Historical Shifts in Developmental Tasks

This study investigated the influence of changing socio-historical conditions on personal goals in young adulthood. It was hypothesized that socio-historical changes related to individualization have resulted in shifts in goal pursuit. Participants from three birth cohorts reconstructed their important goals when they were 20years old. Members of the oldest cohort were born between 1920 and 1925. Members of the middle cohort were born between 1945 and 1950. Members of the youngest cohort were born between 1970 and 1975. Goal content, the degree to which goals were perceived as being shared by members of the same cohort (social sharedness), perceived control over goal attainment, success in attainment, and life satisfaction at age 25 were measured in a retrospective study. Results show consistent shifts over time. Whereas members of older cohorts mentioned goals related to classical developmental tasks, members of younger cohorts mentioned more individualistic, self-related goals and goals related to education. The processes through which goal pursuit influenced life satisfaction also changed. Perceived social sharedness of goals was a direct predictor of life satisfaction for the oldest cohort. For the younger cohorts, perceived control over goal attainment influenced success which in turn influenced life satisfaction. These changes support the contention that developmental tasks and processes are historically varian

Spanish Flu and Mortality Crisis in Salta, Argentina. In Early Twentieth Century

La sociedad salteña, a principios del siglo XX, se caracterizaba por importantes desigualdades de tipo social, que a su vez cristalizaban en problemas en el ámbito de la salud y la educación. Con tasas de mortalidad general e infantil muy altas, ocasionadas por el impacto de dolencias endémicas y epidémicas, la población debía lidiar con graves problemas de salud. No obstante, en 1919 esa situación se agravó, a las epidemias y endemias se sumó la segunda oleada de la pandemia de ?gripe española? generando una crisis de mortalidad. En este artículo se pretende analizar el papel que habría tenido la segunda oleada de gripe española en la provincia y en los Departamentos de la misma que habría generado esta crisis. Para ello se realiza un análisis de carácter cuantitativo con base a datos provistos por la Dirección de Estadísticas de la Provincia de Salta (Argentina), con los cuales se generarán tasas de mortalidad y sobremortalidad que se relacionarán con datos provistos por el censo de población de 1914 proyectados, este análisis será relacionado con datos cualitativos que provee el único periódico de la época encontrado.In the early twentieth century, Salta’s society was characterized by significant social inequalities that were also expressed in the field of health and education. With high overall mortality and infant mortality rates due to the impact of endemic and epidemic diseases, the population had to deal with serious health problems. In 1919, the situation worsened: in addition to epidemics and endemic diseases, the second wave of the “Spanish flu” appeared, resulting in a mortality crisis. The article aims to analyze the role that the second wave of the Spanish flu could have played in Salta and its departments’ crisis. In order to do this, an analysis based on quantitative data provided by the Bureau of Statistics of the Province of Salta will carry out. The statistical data will be used to generate mortality rates and excess mortality that will be related with projected data based on the 1914 Census. This data will also be related with the qualitative information obtained from the only newspaper found from that historical period.Fil: Carbonetti, Adrian. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones y Estudio sobre Cultura y Sociedad; ArgentinaFil: Gomez, Nestor Javier. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; ArgentinaFil: Torres, Victor Eduardo Roque. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones y Estudio sobre Cultura y Sociedad; Argentin