In Latin America early weed competition is a constraint upon upland rice production, leading to i... more In Latin America early weed competition is a constraint upon upland rice production, leading to intensive herbicide use. Breeding for rice competitiveness may help reduce the need for herbicides. Two consecutive screenhouse pot experiments were conducted with 13 upland cultivars grown alone or in mixtures with Brachana brizantha to identify plant characteristics for early rice competitiveness which could serve as selection criteria. Rice growth reduction from B. brizantha competition was evident in all cultivars by 30 d.a.e., and the traits most related to cultivar competitiveness were: total above‐ground plant biomass > leaf weight > stem weight > leaf area. Plant height and tillering were least affected by competition. Rice and B. brizantha partially avoided competition since the competing canopies did not fully intercept the incoming light. Traits measured in monoculture did not correlate well with the competition‐induced growth reductions. In breeding for competitiveness, selection according to the above traits should be conducted on rice growing in competition, rather than in monoculture. A measure of plant biomass or leaf area at 30 d.a.e. appears to provide the most convenient estimates of early interference.
Although intelligence has traditionally been identified as the ability to learn (Peterson, 1925),... more Although intelligence has traditionally been identified as the ability to learn (Peterson, 1925), this relationship has been questioned in simple operant learning tasks (Spielberger, 1962). Nevertheless, recent pieces of research have demonstrated a strong and significant correlation between associative learning measures and intelligence ( and ). The present paper aims to examine the relationship between intelligence and learning, complying with the experimental conditions of discriminative conditioning in a relatively complex free operant task. To that end, a sample of 1600 subjects applying for an ab initio Air Traffic Control training course was tested. The task is expected to allow identifying the specific influence of intelligence on the discrimination between stimulus dimensions. The results show how the relation among learning and intelligence strengthen on those trials which are critical in terms of discrimination.► A FR-3 schedule was used to study the relationship between intelligence and learning. ► 10% of the sample effectively discriminate the contingency schedule. ► Significant differences in intelligence were found between high and low performers. ► Discrimination between stimuli dimensions mainly occurs on trials 2 to 4. ► The relation between intelligence and learning strengthens in trials 2 to 4.
This study focuses on performance differences individuals show when solving a computerized spatia... more This study focuses on performance differences individuals show when solving a computerized spatial-orientation dynamic task, irrespective of their cognitive ability. The hypothesis tested was that differences in performance reflect individuals' cognitive style: Reflection-Impulsivity. The Spatial Orientation Dynamic Task-Revised (SODT-R) and the Analytical, Sequential, and Inductive Reasoning Test (TRASI) were administered to 541 postgraduate participants, as part of the selection process they were following. Reflection-Impulsivity was measured through average response latency and average error score comprising three groups: impulsive, reflective, and medium. Performance was measured by mean response frequency, quality proportion of the first press, and mean invested time. Data were analyzed through discriminant analysis. Criterion variable was Reflection-Impulsivity groups and discriminant variables were performance ones, plus intelligence. Results show different performance patterns clearly associated with Reflection-Impulsivity (canonical correlation = .63). Intelligence played a small role in the differentiation between groups. Findings support the proposal to use spatial orientation tasks as vehicles to measure cognitive style Reflection-Impulsivity in adults. We finally discuss performance patterns as a pathway to ways of acquiring and processing spatial information for impulsives and reflexives, with similar cognitive resources.
It has been suggested that the higher susceptibility of Hispanics to metabolic disease is related... more It has been suggested that the higher susceptibility of Hispanics to metabolic disease is related to their Native American heritage. A frequent cholesterol transporter ABCA1 (ATP-binding cassette transporter A1) gene variant (R230C, rs9282541) apparently exclusive to Native American individuals was associated with low high-density lipoprotein cholesterol (HDL-C) levels, obesity and type 2 diabetes in Mexican Mestizos. We performed a more extensive analysis of this variant in 4405 Native Americans and 863 individuals from other ethnic groups to investigate genetic evidence of positive selection, to assess its functional effect in vitro and to explore associations with HDL-C levels and other metabolic traits. The C230 allele was found in 29 of 36 Native American groups, but not in European, Asian or African individuals. C230 was observed on a single haplotype, and C230-bearing chromosomes showed longer relative haplotype extension compared with other haplotypes in the Americas. Additionally, single-nucleotide polymorphism data from the Human Genome Diversity Panel Native American populations were enriched in significant integrated haplotype score values in the region upstream of the ABCA1 gene. Cells expressing the C230 allele showed a 27% cholesterol efflux reduction (P < 0.001), confirming this variant has a functional effect in vitro. Moreover, the C230 allele was associated with lower HDL-C levels (P 5 1.77 3 10 211 ) and with higher body mass index (P 5 0.0001) in the combined analysis of Native American populations. This is the first report of a common functional variant exclusive to Native American and descent populations, which is a major determinant of HDL-C levels and may have contributed to the adaptive evolution of Native American populations.
In Latin America early weed competition is a constraint upon upland rice production, leading to i... more In Latin America early weed competition is a constraint upon upland rice production, leading to intensive herbicide use. Breeding for rice competitiveness may help reduce the need for herbicides. Two consecutive screenhouse pot experiments were conducted with 13 upland cultivars grown alone or in mixtures with Brachana brizantha to identify plant characteristics for early rice competitiveness which could serve as selection criteria. Rice growth reduction from B. brizantha competition was evident in all cultivars by 30 d.a.e., and the traits most related to cultivar competitiveness were: total above‐ground plant biomass > leaf weight > stem weight > leaf area. Plant height and tillering were least affected by competition. Rice and B. brizantha partially avoided competition since the competing canopies did not fully intercept the incoming light. Traits measured in monoculture did not correlate well with the competition‐induced growth reductions. In breeding for competitiveness, selection according to the above traits should be conducted on rice growing in competition, rather than in monoculture. A measure of plant biomass or leaf area at 30 d.a.e. appears to provide the most convenient estimates of early interference.
Although intelligence has traditionally been identified as the ability to learn (Peterson, 1925),... more Although intelligence has traditionally been identified as the ability to learn (Peterson, 1925), this relationship has been questioned in simple operant learning tasks (Spielberger, 1962). Nevertheless, recent pieces of research have demonstrated a strong and significant correlation between associative learning measures and intelligence ( and ). The present paper aims to examine the relationship between intelligence and learning, complying with the experimental conditions of discriminative conditioning in a relatively complex free operant task. To that end, a sample of 1600 subjects applying for an ab initio Air Traffic Control training course was tested. The task is expected to allow identifying the specific influence of intelligence on the discrimination between stimulus dimensions. The results show how the relation among learning and intelligence strengthen on those trials which are critical in terms of discrimination.► A FR-3 schedule was used to study the relationship between intelligence and learning. ► 10% of the sample effectively discriminate the contingency schedule. ► Significant differences in intelligence were found between high and low performers. ► Discrimination between stimuli dimensions mainly occurs on trials 2 to 4. ► The relation between intelligence and learning strengthens in trials 2 to 4.
This study focuses on performance differences individuals show when solving a computerized spatia... more This study focuses on performance differences individuals show when solving a computerized spatial-orientation dynamic task, irrespective of their cognitive ability. The hypothesis tested was that differences in performance reflect individuals' cognitive style: Reflection-Impulsivity. The Spatial Orientation Dynamic Task-Revised (SODT-R) and the Analytical, Sequential, and Inductive Reasoning Test (TRASI) were administered to 541 postgraduate participants, as part of the selection process they were following. Reflection-Impulsivity was measured through average response latency and average error score comprising three groups: impulsive, reflective, and medium. Performance was measured by mean response frequency, quality proportion of the first press, and mean invested time. Data were analyzed through discriminant analysis. Criterion variable was Reflection-Impulsivity groups and discriminant variables were performance ones, plus intelligence. Results show different performance patterns clearly associated with Reflection-Impulsivity (canonical correlation = .63). Intelligence played a small role in the differentiation between groups. Findings support the proposal to use spatial orientation tasks as vehicles to measure cognitive style Reflection-Impulsivity in adults. We finally discuss performance patterns as a pathway to ways of acquiring and processing spatial information for impulsives and reflexives, with similar cognitive resources.
It has been suggested that the higher susceptibility of Hispanics to metabolic disease is related... more It has been suggested that the higher susceptibility of Hispanics to metabolic disease is related to their Native American heritage. A frequent cholesterol transporter ABCA1 (ATP-binding cassette transporter A1) gene variant (R230C, rs9282541) apparently exclusive to Native American individuals was associated with low high-density lipoprotein cholesterol (HDL-C) levels, obesity and type 2 diabetes in Mexican Mestizos. We performed a more extensive analysis of this variant in 4405 Native Americans and 863 individuals from other ethnic groups to investigate genetic evidence of positive selection, to assess its functional effect in vitro and to explore associations with HDL-C levels and other metabolic traits. The C230 allele was found in 29 of 36 Native American groups, but not in European, Asian or African individuals. C230 was observed on a single haplotype, and C230-bearing chromosomes showed longer relative haplotype extension compared with other haplotypes in the Americas. Additionally, single-nucleotide polymorphism data from the Human Genome Diversity Panel Native American populations were enriched in significant integrated haplotype score values in the region upstream of the ABCA1 gene. Cells expressing the C230 allele showed a 27% cholesterol efflux reduction (P < 0.001), confirming this variant has a functional effect in vitro. Moreover, the C230 allele was associated with lower HDL-C levels (P 5 1.77 3 10 211 ) and with higher body mass index (P 5 0.0001) in the combined analysis of Native American populations. This is the first report of a common functional variant exclusive to Native American and descent populations, which is a major determinant of HDL-C levels and may have contributed to the adaptive evolution of Native American populations.
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Papers by Camilo Lozano