Modeling oil price uncertainty effects on economic growth in Mexico: a sector-level analysis

This paper analyzes the impact of international oil price uncertainty on the different economic sectors (primary, secondary, and tertiary) in Mexico in the period 1993:1–2020:4 through a bivariate structural vector autoregressive (VAR) model with a generalized autoregressive conditional heteroskedasticity (GARCH) in mean to capture the impact of oil volatility on economic growth at the sectoral level of economic activity. The results show that the uncertainty of the international price of oil has a differentiated effect on the different sectors of economic activity in Mexico since it does not influence the primary sector; it negatively impacts the secondary sector, and there is mixed evidence in the tertiary sector. Additionally, evidence is provided that both positive and negative shocks to the international oil price have asymmetric effects at the sectoral level in Mexico. The results highlight the need to implement public policies, at the country level, that help mitigate the effect of uncertainty in the oil market and promote economic stability at the sector level.

     

The distribution of 210Pb in human bone and its impact on methods for the retrospective estimation of 222Rn exposure from in vivo measurements

It is possible to estimate radon exposure to man retrospectively by the in vivo measurement of the decay product (210)Pb, which accumulates in the bones. For in vivo methods, knowledge of the distribution of (210)Pb in the skeleton is needed to determine the optimal site for measurement, the skull or the knee. In this study the activity of (210)Pb in a variety of bone samples from 3 individuals have been measured in vitro using underground gamma-ray spectrometry. The individuals were unlikely to have had elevated intakes of Rn. These measurements give baseline data on the bone massic activity of (210)Pb. They show that the massic activity is similar for each of these people and there are similar massic activities of (210)Pb in the skull and the knee of the 2 individuals for which the skull was measured. Additionally for 2 of the individuals trabecular and cortical bone were separated and massic activities were found to be strongly correlated indicating that the (210)Pb is associated with the hydroxyapatite.     

Hazard,vulnerability and coastal erosion risk assessment in Necochea Municipality,Buenos Aires Province,Argentina

This contribution determines the coastal erosion risk of Necochea and Quequén cities, Necochea Municipality, Buenos Aires Province (Argentina). Both risk components, hazard and vulnerability, were assessed by the construction of indices. The hazard index is composed of four indicators: the erosion or accretion rate, coastal geomorphology, storm waves effects, and sediment supply. The vulnerability index is comprised of land use/cover, demographic, life conditions, and work and consumption indicators, and includes population census data such as demographic, education, health, sanitary, economic, production, work and population exposure aspects. The analysis concluded that coastal erosion risk ranges from very low to high along the study area, Quequén yielding the highest values. Risk levels vary in both cities based on the uneven spatial distribution of hazard. The risk assessment developed herein constitutes a practical and adequate tool that can be utilized with other elements and tasks in the elaboration of a coastal management program.     

An unforgettable event: a qualitative study of the 1997–98 El Niño in northern Peru

During the 1997–98 El Niño, Tumbes, Peru received 16 times the annual average rainfall. This study explores how Tumbes residents perceived the impact of the El Niño event on basic necessities, transport, health care, jobs and migration. Forty‐five individuals from five rural communities, some of which were isolated from the rest of Tumbes during the event, participated in five focus groups; six of these individuals constructed nutrition diaries. When asked about events in the past 20 years, participants identified the 1997–98 El Niño as a major negative event. The El Niño disaster situation induced a decrease in access to transport and health care and the rise in infectious diseases was swiftly contained. Residents needed more time to rebuild housing; recover agriculture, livestock and income stability; and return to eating sufficient animal protein. Although large‐scale assistance minimized effects of the disaster, residents needed more support. Residents' perspectives on their risk of flooding should be considered in generating effective assistance policies and programmes.     

Assessment of the in vivo genotoxicity of a new formulation of Bacillus thuringiensis var israelensis SH-14

Biological control agents have become a useful alternative for the reduction of the use of chemical insecticides. LABIOFAM (Cuba) is developing a new formulation of a biolarvicide that possesses as active biological agent Bacillus thuringiensis var israelensis serotype H14. In order to evaluate the genotoxicity of this new formulation, an in vivo battery test was used: micronucleus (MN), chromosome aberrations (CAs), and sperm morphology (SM) assays. A dose of 6.45?×?10⁸ spores was administered per animal via oral administration. Bone marrow cells were collected 24?h after a two day treatment for the MN assay, and 24?h after a unique treatment for the CA assay, using cyclophosphamide as the positive control. Sperm cells were collected at 5 weeks from the first of five administrations for the SM test, using acrylamide as positive control. Bacillus thuringiensis var israelensis serotype H14 failed to show either a significative increase of micronucleated polychromatic erythrocytes, chromosomal aberrations, or sperm abnormalities. Acute oral administration of a high dose of Bacillus thuringiensis var israelensis serotype H14 did not produce mutagenic effects in bone marrow or sperm cells.     

Trends in precipitation chemistry in Alaska, 1980–1998

Nineteen years (1980–1998) of precipitation chemistry data from a site in Alaska are examined for trends using a least squares general linear model. The annual concentrations of SO^2– ₄ show a significant decreasing trend at 0.001 level and the annual change in concentration is —0.012mg 1^–1 yr^–1. The annual concentrations of NO ^– ₃ show an increasing tendency non‐significant. The annual base cation concentrations show a clear significant decreasing trend at 0.001 level and the decrease is —0.009mg 1^–1 yr^–1. Ca²⁺ concentrations exhibit a significant decreasing trend at 0.001 level and the annual change of concentration is —0.003 mg 1^–1 yr^–1. Mg²⁺ and Na⁺ concentrations show a significant decreasing trend at 0.01 level and the annual change is —0.001 mg1^–1 yr^–1 for Mg²⁺ and —0.004 mg1^–1 yr^–1 for Na⁺. K⁺ concentrations are characterised by a decreasing trend, significant at 0.05 level. K⁺ concentrations have decreased —0.002mg1^–1 yr^–1. The strongest rates of concentration decline for base cations, Ca²⁺, Mg²⁺, K⁺ and Na⁺ occurred in fall and winter season. The annual values of pH show a decreasing trend non‐significant. The values of pH oscillate between 5.1 and 5.6 during the period considered.     

Analysis of the ph in Europe during the period 1986–1997

The annual averages (1986–1997) of pH are analysed for the most important European Monitoring and Evaluation Programme stations in Europe. The first objective is to discover the different temporal patterns and trends for the pH. To do this, a cluster analysis is developed. The trends are analysed by linear regression for the annual averages. In general, the pH shows an increasing trend significant at 0.05 level and the annual change ranging from +0.01 to +0.05 pH‐units per year for the different clusters obtained. The second objective is to examine the spatial variability of pH in precipitation through the use of principal component analysis. Six statistically significant modes of variability are obtained for the pH which represent the 84.5% of the total variance.     

Multidimensional trade-offs in species responses to disturbance: implications for diversity in a subtropical forest

Species employ diverse strategies to cope with natural disturbance, but the importance of these strategies for maintaining tree species diversity in forests has been debated. Mechanisms that have the potential to promote tree species coexistence in the context of repeated disturbance include life history trade-offs in colonization and competitive ability or in species' ability to survive at low resource conditions and exploit the temporary resource-rich conditions often generated in the wake of disturbance (successional niche). Quantifying these trade-offs requires long-term forest monitoring and modeling. We developed a hierarchical Bayes model to investigate the strategies tree species employ to withstand and recover from hurricane disturbance and the life history trade-offs that may facilitate species coexistence in forests subject to repeated hurricane disturbance. Unlike previous approaches, our model accommodates temporal variation in process error and observations from multiple sources. We parameterized the model using growth and mortality data from four censuses of a 16-ha plot taken every five years (1990-2005), together with damage data collected after two hurricanes and annual seed production data (1992-2005). Species' susceptibilities to hurricane damage as reflected by changes in diameter growth and fecundity immediately following a storm were weak, highly variable, and unpredictable using traditional life history groupings. The lower crowding conditions (e.g., high light) generated in the wake of storms, however, led to greater gains in growth and fecundity for pioneer and secondary-forest species than for shade-tolerant species, in accordance with expectation of life history. We found moderate trade-offs between survival in high crowding conditions, a metric of competitive ability, and long-distance colonization. We also uncovered a strong trade-off between mean species fecundity in low crowding conditions, a metric of recovery potential, and competitive ability. Trade-offs in competitive and colonization ability, in addition to successional niche processes, are likely to contribute to species persistence in these hurricane-impacted forests. The strategies species employ to cope with hurricane damage depend on the degree to which species rely on sprouting, repair of adult damage, changes in demographic rates in response to enhanced resource availability after storms, or long-distance dispersal as recovery mechanisms.     

Bioavailability, ecotoxicity, and geological characteristics of trace lead in sediments from two sites on Negro River, Uruguay, South America

Bioassays of two sites along the Rio Negro in Uruguay indicate ecotoxicity, which could be attributable to trace concentrations of lead in river sediments. Monthly samples at two sites at Baygorria and Bonete locations were analyzed for both particle size and lead. Lead was determined by atomic spectrometry in river water and sediment and particle size by sieving and sedimentation. Data showed that Baygorria's sediments have greater percentage of clay than Bonete's (20.4 and 5.8%, respectively). Lead was measurable in Baygorria's sediments, meanwhile in Bonete's, it was always below the detection limit. In water samples, lead was below detection limit at both sites. Bioassays using sub-lethal growth and survival test with Hyalella curvispina amphipod, screening with bioluminescent bacteria Photobacterium leiognathi, and acute toxicity bioassay with Pimephales promelas fish indicated toxicity at Baygorria, with much less effect at Bonete. Even though no lethal effects could be demonstrated, higher sub-lethal toxicity was found in samples from Baygorria site, showing a possible concentration of the contaminant in the clay fraction.