Regional Convergence in Latin America: 1980-2000

The objective of the work is to determine the existence of convergence (absolute and conditional) for the region of Latin America and to determine the main variables that affect the economic growth of these countries. The main results are the following ones: there is empirical evidence of absolute and conditional convergence in the period from study to a rate very similar to found by other studies for other groups of countries or regions of the interior of a same country (around the 2 percent).Convergencia; crecimiento economico; capital humano; America Latina; Latinoamerica

Convergencia Regional en América Latina: 1980-2000

The objective of the work is to determine the existence of convergence (absolute and conditional) for the region of Latin America and to determine the main variables that affect the economic growth of these countries. The main results are the following ones: there is empirical evidence of absolute and conditional convergence in the period from study to a rate very similar to found by other studies for other groups of countries or regions of the interior of a same country (around the 2 percent)

Microalgae Cultivation for Secondary Metabolite Production

Microalgae including cyanobacteria have been recognized as an excellent source of fine chemicals, renewable fuels, vitamins, and proteins and usually are found in health food stores around the world. However, the accumulation of these compounds generally occurs at end of the exponential growth phase; furthermore, biomass density in cultivation commonly is low. Open cultures have been used for pigment, biofuels, and biomass production, but these types of culture system are not a good choice for the production of fine chemicals, due to contamination problems and the expensive production costs. Closed photobioreactors can be operated in a continuous cultivation providing an increase on biomass density and contamination-free condition and generally working at a maximum growth rate under specific conditions; besides, these systems can recycle the consumed culture medium at least three times before a new enriched medium is supplied, generating a more cost-effective production system. In addition, microalgae metabolism can be manipulated to provoke a specific secondary metabolite accumulation by the addition of organic carbon source or changing light intensity or both. In other words, photobioreactors can operate in continuous mode, with efficient light supply and the supplementation of organic carbon source to produce fine biochemicals such as anticancer, antibacterial, antioxidant, lectins, antiviral compounds, and biofuels

Morphological and Physicochemical Characterization of Agglomerates of Titanium Dioxide Nanoparticles in Cell Culture Media

Titanium dioxide nanoparticles (TiO2 NP) are possible carcinogenic materials (2B-IARC) and their toxicity depends on shape, size, and electrical charge of primary NP and on the system formed by NP media. The aim of this work was to characterize agglomerates of three TiO2 NP by evaluating their morphometry, stability, and zeta potential (ζ) in liquid media and their changes with time. Sizes of agglomerates by dynamic light scattering (DLS) resulted to be 10–50 times larger than those obtained by digital image analysis (DIA) given the charged zone around particles. Fractal dimension (FD) was highest for agglomerates of spheres and belts in F12K, and in E171 in FBS media. E171 and belts increased FD with time. At time zero, using water as dispersant FD was larger for agglomerates of spheres than for of E171. Belts suspended in water had the smallest values of circularity (Ci) which was approximately unchanged with time. All dispersions had ζ values around −30 mV at physiological pH (7.4) and dispersions of NP in water and FBS showed maximum stability (Turbiscan Lab analysis). Results help in understanding the complex NP geometry-size-stability relationships when performing in vivo and in vitro environmental-toxicity works and help in supporting decisions on the usage of TiO2 NP

Racism as a determinant of health: a systematic review and meta-analysis

Despite a growing body of epidemiological evidence in recent years documenting the health impacts of racism, the cumulative evidence base has yet to be synthesized in a comprehensive meta-analysis focused specifically on racism as a determinant of health. This meta-analysis reviewed the literature focusing on the relationship between reported racism and mental and physical health outcomes. Data from 293 studies reported in 333 articles published between 1983 and 2013, and conducted predominately in the U.S., were analysed using random effects models and mean weighted effect sizes. Racism was associated with poorer mental health (negative mental health: r = -.23, 95% CI [-.24,-.21], k = 227; positive mental health: r = -.13, 95% CI [-.16,-.10], k = 113), including depression, anxiety, psychological stress and various other outcomes. Racism was also associated with poorer general health (r = -.13 (95% CI [-.18,-.09], k = 30), and poorer physical health (r = -.09, 95% CI [-.12,-.06], k = 50). Moderation effects were found for some outcomes with regard to study and exposure characteristics. Effect sizes of racism on mental health were stronger in cross-sectional compared with longitudinal data and in non-representative samples compared with representative samples. Age, sex, birthplace and education level did not moderate the effects of racism on health. Ethnicity significantly moderated the effect of racism on negative mental health and physical health: the association between racism and negative mental health was significantly stronger for Asian American and Latino(a) American participants compared with African American participants, and the association between racism and physical health was significantly stronger for Latino(a) American participants compared with African American participants.<br /

Electromagnetic Radiation in chiral matter: the Cherenkov case

Starting from the modified Maxwell equations in Carroll-Field-Jackiw electrodynamics we study the electromagnetic radiation in a chiral medium characterized by an axion coupling $\theta(x)=b_\mu x^\mu$, with $b_\mu= (0,\mathbf{b})$, which gives rise to the magnetoelectric effect. Employing the stationary phase approximation we construct the Green's matrix in the radiation zone which allows the calculation of the corresponding electromagnetic potentials and fields for arbitrary sources. We obtain a general expression for the angular distribution of the radiated energy per unit frequency. As an application we consider a charge moving at constant velocity parallel to $\mathbf{b}$ in the medium and discuss the resulting Cherenkov radiation. We recover the vacuum Cherenkov radiation. For the case of a material with refraction index $n > 1$ we find that zero, one or two Cherenkov cones can appear. The spectral distribution of the radiation together with the comparison of the radiation output of each cone are presented, as well as some angular plots showing the appearance of the cones.Comment: Submitted to Physical Review

Potato Ingestion as an Effective Race Fuel Alternative to Improve Cycling Performance in Trained Cyclists

Carbohydrate (CHO) ingestion is an established strategy to improve endurance performance. Race fuels should not only sustain performance, but also be readily digested and absorbed and replenish electrolytes. Potatoes are a cost-effective option that fulfills these criteria; however, their impact on endurance performance remains unexamined. PURPOSE: Compare the effects of potato purée (POT) ingestion during endurance cycling on subsequent performance versus commercial CHO gel (GEL) or a control (water, CTL). METHODS: Twelve trained cyclists (31±9y; 71±8kg; VO2max: 61±9mL/kg/min) consumed a standardized breakfast then performed a 2h cycling challenge (60-85%VO2max) followed by a time trial (6kJ/kg body mass) while consuming POT, GEL, or CTL in a randomized-crossover design. POT, GEL and CTL were administered with U-[13C6]glucose for an indirect estimate of gastric emptying rate. Repeated blood samples were collected. RESULTS: Time trial performance significantly improved (P=0.03) with POT (33.0±4.5min) and GEL (33.0±4.2min) versus CTL condition (39.5±7.9min); while POT and GEL conditions (P=1.00) had no difference. Post-challenge, blood glucose concentrations were lower (P0.05). CONCLUSION: Potatoes served as a viable alternative to commercial gels by sustaining performance and blood glucose concentrations during endurance cycling events in trained cyclists

El valor de las emisiones de carbono asociadas al sistema agrícola de roza, tumba y quema

A large part of Mexico´s forests are degraded but present the opportunity for recuperation of carbon stocks through natural growth, once the drivers of degradation are removed. However, there are opportunity costs involved since most of the drivers are related to economic activities including shifting cultivation and cattle grazing. The study calculates the economic costs of sequestration of carbon in tropical dry forest (TDF) in western Mexico based on an analysis of such opportunity costs. Results may help policy makers and land managers make informed decisions about whether to engage in international programs such as Reduced Emissions from Deforestation and forest Degradation (REDD+)

La roza tumba y quema en el contexto de REDD+

Slash and burn (RTQ) is an agricultural system that in the context of climate change has been seen as one of those responsible for deforestation and intensive agriculture (AP) has been proposed to replace it in order to decrease gas greenhouse issued. We evaluated the impact of the RTQ in carbon stocks and fluxes in the context of international politics REDD+. The study was conducted in two communities Ayuquila Basin, Jalisco River. Stores Air carbon and soil in six land uses (pastures, intensive agriculture, RTQ production, RTQ at rest, sites PSA and sites forest that had never been cut), then comparisons between them were conducted were compared. Additionally, carbon stocks and associated with a cycle of ten years of RTQ flows were compared with those of a PA system. We found that C stores in RTQ plots are smaller than those found in best- preserved sites, so we support the idea that the RTQ is a cause of forest degradation. We also found that on average per ton of corn produced, long-term differences in carbon stocks are relatively small; However, although we found that global emissions of a cycle RTQ are higher than those of a PA system, this does not justify the RTQ be replaced by a more intensive system in order to mitigate climate change, especially by inputs not considered