morphology

We present a cladistic analysis of all the species of Smallanthus. Six taxa within Rumfordia, Ichthyothere, Acanthospermum and Tridax served as outgroups. We evaluated the monophyly and the relationships between the species of Smallanthus through a maximum parsimony study based on morphological data. The matrix included 31 qualitative characters from floral and vegetative parts of the specimens. We also explored the phylogenetic significance of treating quantitative characters as continuous. Only one most parsimonious tree was obtained. In agreement with previous phylogenetic studies based on molecular data, we recovered a monophyletic Smallanthus. The presence of ray corollas, densely pubescent at the base, was the synapomorphy that defined Smallanthus. Smallanthus microcephalus and two other major clades were recovered. The first clade included S. glabratus, S. fruticosus, S. jelskii and S. pyramidalis, while the second one contained the remaining species of Smallanthus. The analysis recovered one species of Rumfordia as sister to Smallanthus. We present a new combination, Smallanthus cocuyensis, based on morphological analysis of the type specimen

Vitamina C : una estrategia didáctica polifuncional

El presente trabajo tiene como objetivo contextualizar contenidos curriculares de química: incursionando en el área de bioquímica, como elementos básicos de la formación en química del estudiante; proporcionando información general sobre las propiedades de la vitamina C que permitan al estudiante, como ciudadano, tener libertad de elección frente a la vasta publicidad que se ofrece, entre otros, en los medios masivos de comunicación; aplicando su cultura científica a situaciones de la vida cotidiana y, por lo tanto, valorando la importancia de la educación científica para poder ser capaz de conocer mejor lo que consume y poder opinar en forma crítica sobre ello. Se presentan técnicas sencillas para investigar la presencia de vitamina C en alimentos de uso común. Se discuten distintas estrategias de presentación y tratamiento del tema en los distintos niveles escolares con objetivos diferentes y se analizan cambios en la metodología de trabajo en el aula. Este trabajo fue presentado bajo la modalidad de taller en el XV Congreso Nacional e Internacional de Profesores de Química y los resultados y conclusiones a las que se arribaron fueron ampliamente satisfactorias, ya que permitieron una revalorización de la tarea educativa buscando un currículo más abierto donde el estudiante se sienta partícipe de su proceso de aprendizaje y encuentre contenidos científicos útiles para su vida.This paper attempts to contextualise chemistry curricula contents, entering the field of biochemistry, as basic elements for the formation of chemistry in the student by providing general information on the properties of C vitamin that allows the student, as a citizen, the freedom to choose in front of the huge publicity offered to them, among others, by the mass media. They can apply their scientific culture to everyday life, thus assessing how important scientific education is to be able to better know what is consumed and give a critical opinion. We present simple techniques to find C vitamin in commonly used food. We discuss different strategies to present and deal with this subject at different school levels with different aims, and we analyse the changes in the classroom working methodology. This paper was presented as a workshop in the 15th National and International Congress of Chemistry Professors and its results and conclusion were highly satisfactory, as they allowed revaluing the educational task aiming at a more open curriculum where the student feels part of his learning process and finds scientific contents useful in his everyday life

Analysis of fluid velocity inside an agricultural sprayer using generalized linear mixed models

The fluid velocity inside the tank of agricultural sprayers is an indicator of the quality of the mixture. This study aims to formulate the best generalized linear mixed model to infer the fluid velocity inside a tank under specific operational parameters of the agitation system, such as liquid level, circuit pressures, and number of active nozzles. A complex model was developed that included operational parameters as fixed eects (FE) and the section of the tank as the random eect. The goodness of fit of the model was evaluated by considering the lowest values of Akaike''s information criteria and Bayesian information criterion, and by estimating the residual variance. The gamma distribution and log-link function enhanced the goodness of fit of the best model. The Toeplitz structure was chosen as the structure of the covariance matrix. SPSS and SAS software were used to compute the model. The analysis showed that the greatest influence on the fluid velocity was exerted by the liquid level in the tank, followed by the circuit pressure and, finally, the number of active nozzles. The development presented here could serve as a guide for formulating models to evaluate the eciency of the agitation system of agricultural sprayers

Fattening Commercial Zebu with Grazing and Low Supplementation on Small Farms.

The aim of this paper was to describe and group grazing commercial Zebu bulls, with low supplementation. Forty-four beef-producing farms from several cooperatives of credits and services were studied. Their members are private farmers from Sibanicu, Camaguey, Cuba. The farms were visited for three years,  and official records were made of each farmer for these variables: resources, animals, management, production, and economy. The main statigraph for the variables were calculated. The  average  initial weight, final weight, weight gain, and production per ha were, 202.6; 371.6; 501; and 326.2 kg, during 339.7 fattening days, respectively. The principal component  analysis (PCA) showed  a Kaiser-Meyer-Olkin coefficient higher than 0.66, and a significant Bartlett  sphericity  coefficient (P < 0.01), with self-values above 1. The two groups were made using a BIETAPIC cluster analysis

Changes in some physical properties of a typic haplorthox in southern Brazil under no-tillage crop rotation systems

The assessment of the impacts of different crop rotations on soil physical properties is needed to identify those with the potential to improve such properties which enhance crops´ responses to soil nutrients. The effects of eight crop rotations on physical properties of a Rhodic Ferralsol (Typic Haplorthox) were assessed in Palmital, Svo Paulo, Brazil, using a randomized complete block design with three replications of each treatment. The study lasted for five years (1985 –1990). The crop rotations, planted during the winter from 1985 to 1987, were mucuna, pigeon pea, rye, oat, pisum, wheat, crotalaria and black oat. In 1988 wheat was planted on all plots and from 1989 to 1990, lathyrus, lupin, rye, oat, lupin + black oat, wheat, crotalaria and black oat were planted. The summer crops were maize and soybean. In all treatments and taking the average of all the soil horizons, lupin+black oat and lathyrus produced the lowest bulk density in both maize and soybean plots. When the ranking of the performance of these crop rotations was performed, the order in the maize plots was lupin+black oat > rye > lathyrus > lupin/wheat > oat > crotalaria/black oat. On soybean plots the order was lathyrus > lupin > lupin+black oat > rye > oat > crotalaria > black oat > wheat. It is evident that for the summer crops, lupin+black oat, rye, lathyrus and lupin were consistent in improving these soil physical properties and are therefore, better than the rest of the rotation crops in moderating these properties. Even though there was low improvement in OM content of the soil, OM moderated very significantly bulk density (r =0.602**) and saturated hydraulic conductivity (Ksat) (r = 0.674**) under soybean plots. However, macro-porosity (Pe) had positive improvement in Ksat (r = 0.684**) under maize of all the physical properties measured. Longer lasting crop rotations may produce more positive influences of OM on these soil physical properties. Keywords: Water holding capacity; Aggregate stability; Saturated hydraulic conductivity; Bulk density; Organic matter; Maize; Soybean. Agro-Science Vol. 3 (2) 2006: pp. 1-1

Technical Efficiency of Dairy Farms in Sierra Andina Using Neural Network Modeling

The aim of this paper was to estimate the efficiency of milk production of 1 168 cases in Ecuadoran Sierra Sur Andina, with the implementation of a neural network model with multilayer perceptrons. These cases were collected from secondary samples provided by the Official Institute of National Statistics of Ecuador, in 2016. The variables chosen for the model were total milk production on the previous day (P), as dependent variable, and total cattle heads (CH), total laborers in the field (E), and total area attended by laborer (S), as independent variables. The data from individual cases and their impact on the dependent variable were used as the variable selection criteria. The average efficiency was 8.11%, from which the total efficient cases detected (>0.70) were 11 (0.9% of the sample). Later, the cases studied were classified into three groups, depending on the estimated efficiency: Group 1 (≤ 0.4 efficiency); Group 2 (>0.4-≤0.7 efficiency); and Group 3 (>0.7 efficiency). A comparison produced several statistical differences (P<0.01) for variables total milk production/year on the farm, total field laborers, farm size, total cows, total cattle heads, calvings, pregnant cows, and served cows.The aim of this paper was to estimate the efficiency of milk production of 1 168 cases in Ecuadoran Sierra Sur Andina, with the implementation of a neural network model with multilayer perceptrons. These cases were collected from secondary samples provided by the Official Institute of National Statistics of Ecuador, in 2016. The variables chosen for the model were total milk production on the previous day (P), as dependent variable, and total cattle heads (CH), total laborers in the field (E), and total area attended by laborer (S), as independent variables. The data from individual cases and their impact on the dependent variable were used as the variable selection criteria. The average efficiency was 8.11%, from which the total efficient cases detected (>0.70) were 11 (0.9% of the sample). Later, the cases studied were classified into three groups, depending on the estimated efficiency: Group 1 (≤ 0.4 efficiency); Group 2 (>0.4-≤0.7 efficiency); and Group 3 (>0.7 efficiency). A comparison produced several statistical differences (P<0.01) for variables total milk production/year on the farm, total field laborers, farm size, total cows, total cattle heads, calvings, pregnant cows, and served cows

Signature of chaos in gravitational waves from a spinning particle

A spinning test particle around a Schwarzschild black hole shows a chaotic behavior, if its spin is larger than a critical value. We discuss whether or not some peculiar signature of chaos appears in the gravitational waves emitted from such a system. Calculating the emitted gravitational waves by use of the quadrupole formula, we find that the energy emission rate of gravitational waves for a chaotic orbit is about 10 times larger than that for a circular orbit, but the same enhancement is also obtained by a regular "elliptic" orbit. A chaotic motion is not always enhance the energy emission rate maximally. As for the energy spectra of the gravitational waves, we find some characteristic feature for a chaotic orbit. It may tell us how to find out a chaotic behavior of the system. Such a peculiar behavior, if it will be found, may also provide us some additional informations to determine parameters of a system such as a spin.Comment: 14 pages, LaTeX, to appear in Phys. Rev.

Evaluation of Fattening Efficiency of Grazing Bulls through Panel Data Envelop Analysis

The purpose of this paper was to assess fattening efficiency changes in grazing bulls, using panel data envelop analysis in two periods of time. The panel data were compiled by DEAP 2.1, which included the results of a 3-year period from 38 private farms (beef farms) in cooperatives of credits and services. The farms were on prairie savannahs, located on 21.4831 latitude, and -77.3174 longitude, less than 300 meters above sea level, province of Camagüey, mideastern Cuba. The output variable was total sold kg (TSKG), and the input variables were cost of Norgold (CN), fuel kg per ha (FKGXHA), fuel kg per livestock unit (FKGXLU), and unit of human labor force (UHL), which were highly correlated to the output variable. Table 2 shows that technical efficiency (TE), pure efficiency (PEC), and scale sufficiency (SEC), underwent 0.2%, 0.4, and 0.5%, respectively, by the third year of fattening. Technological change (TC) between the second and third years rose to almost 14%, and the total productivity factor (TPF) spiked as farmers became more skilled and experienced, with a 4.9% increase in comparison to the first year, and 13.7% in the second year