Recent brazilian experience on farmer reaction and crop response to fertilizer use

(1) In the period 1965/77 fertilizer consumption in Brazil increased nearly fifteen foild from circa 200,000 tons of N + P2O5 + K2O to 3 million tons. During the fifteen years extending from 1950 to 1964 usage of the primary macronutrients was raised by a factor of 2 only. (2) Several explanations are given for the remarkable increase, namely: an experimental background which supplied data for recommendations of rates, time and type of application; a convenient governmental policy for minimum prices and rural credit; capacity of the industry to meet the demand of the fertilizer market; an adequate mechanism for the diffusion of the practice of fertilizer use to the farmer. (3) The extension work, which has caused a permanent change in the aptitude towards fertilization, was carried out in the traditional way by salesmen supported by a technical staff, as well as by agronomists of the official services. (4) Two new programs were started and conducted in a rather short time, both putting emphasis on the relatively new technology of fertilizer use. (5) The first program, conducted in the Southern part of the country, extended lab and green house work supplemented by a few field trials to small land owners - the so called "operação tatú" (operation armadillo). (6) The seconde program, covering a larger problem area in the Northeast and in Central Brazil, began directly in field as thousands of demonstrations and simple experiments with the participation of local people whose involvement was essential for the success of the initiative; in this case the official extension services, both foreign and national sources of funds, and universities did participate under the leadership of the Brazilian Association for the Diffusion of Fertilizers (ANDA). (7) It is felt that the Brazilian experience gained thereof could be useful to other countries under similar conditions.

Optimal control of a Stefan problem with gradient-based methods in FEniCS

Otto-von-Guericke-Universität Magdeburg, Fakultät für Mathematik, Masterarbeit, 2016

Population biology of Eudendrium caraiuru (Cnidaria, Anthoathecata, Eudendriidae) from São Sebastião Channel, Southeastern Brazil

The ecology of Eudendrium spp. from the Brazilian coast is poorly known, although it already proved to be useful and important as a tool to solve some taxonomical problems of the genus. The seasonality and reproduction patterns of a population of Eudendrium caraiuru Marques & Oliveira, 2003 were studied. Data were sampled from test panels immersed in the water off Cabelo Gordo de Dentro beach, in São Sebastião Channel, Southeastern Brazil, from July 1999 to July 2000, every three months. Eudendrium caraiuru was active throughout the study period. Reproductive peaks of the species were regulated by cold and low-salinity water, although part of the population always bore mature gonophores. In addition to morphological differences, ecological differences between E. caraiuru and its similar species, E. glomeratum Picard, 1951, especially from well known populations of the Mediterranean Sea, corroborated that these species are diverse lineages of a unique ancestor.

Morphology and development of the postcranial skeleton in the channel catfish Ictalurus punctatus (Ostariophysi: Siluriformes) / Terry Grande, Judith D. Shardo.

n.s. no.99(2002)

Space-time variation of the relative abundance of Limnoperna fortunei in deep zones of São Gonçalo Channel, Rio Grande do Sul, Brazil

This work describes the spatial-temporal variation of the relative abundance and size of Limnoperna fortunei (Dunker, 1857) collected in São Gonçalo Channel through bottom trawl with a 0.5 cm mesh, at depths between 3 and 6 m. The estimative of mean relative abundance (CPUE) ranged from 2,425.3 individuals per drag (ind./drag) in the spring to 21,715.0 ind./drag in the fall, with an average of 9,515.3 ind./drag throughout the year. The estimated mean density of L. fortunei for the deep region of São Gonçalo Channel ranged from 1.2 to 10.3 ind./m², and it was recorded a maximum density of 84.9 ind./m² in the fall of 2008. The method of sampling using bottom trawl enabled the capture of L. fortunei under the soft muddy bottom of the channel, in different sizes ranging from 0.4 to 3.2 cm. This shows that the structure of the L. fortunei adult population under the bottom of the São Gonçalo Channel is composed mostly of small individuals (<1.4 cm), which represent up to 74% of the population collected.

The orthogonal subcategory problem in homotopy theory

It is known that, in a locally presentable category, localization exists with respect to every set of morphisms, while the statement that localization with respect to every (possibly proper) class of morphisms exists in locally presentable categories is equivalent to a large-cardinal axiom from set theory. One proves similarly, on one hand, that homotopy localization exists with respect to sets of maps in every cofibrantly generated, left proper, simplicial model category M whose underlying category is locally presentable. On the other hand, as we show in this article, the existence of localization with respect to possibly proper classes of maps in a model category M satisfying the above assumptions is implied by a large-cardinal axiom called Vopënka's principle, although we do not know if the reverse implication holds. We also show that, under the same assumptions on M, every endofunctor of M that is idempotent up to homotopy is equivalent to localization with respect to some class S of maps, and if Vopënka's principle holds then S can be chosen to be a set. There are examples showing that the latter need not be true if M is not cofibrantly generated. The above assumptions on M are satisfied by simplicial sets and symmetric spectra over simplicial sets, among many other model categories.

Periodic orbits of the planar collision restricted 3-body problem

Using the continuation method we prove that the circular and the elliptic symmetric periodic orbits of the planar rotating Kepler problem can be continued into periodic orbits of the planar collision restricted 3–body problem. Additionally, we also continue to this restricted problem the so called “comets orbits”.

Polynomial-time complexity for instances of the endomorphism problem in free groups

We say the endomorphism problem is solvable for an element W in a free group F if it can be decided effectively whether, given U in F, there is an endomorphism Φ of F sending W to U. This work analyzes an approach due to C. Edmunds and improved by C. Sims. Here we prove that the approach provides an efficient algorithm for solving the endomorphism problem when W is a two- generator word. We show that when W is a two-generator word this algorithm solves the problem in time polynomial in the length of U. This result gives a polynomial-time algorithm for solving, in free groups, two-variable equations in which all the variables occur on one side of the equality and all the constants on the other side.

Periodic orbits near a heteroclinic loop formed by one dimensional orbit and a 2-dimensional manifold: application to the charged collinear 3-body problem

The paper is devoted to the study of a type of differential systems which appear usually in the study of some Hamiltonian systems with 2 degrees of freedom. We prove the existence of infinitely many periodic orbits on each negative energy level. All these periodic orbits pass near the total collision. Finally we apply these results to study the existence of periodic orbits in the charged collinear 3–body problem.

Bribe-proof rules in the division problem

The division problem consists of allocating an amount of a perfectly divisible good among a group of n agents with single-peaked preferences. A rule maps preference profiles into n shares of the amount to be allocated. A rule is bribe-proof if no group of agents can compensate another agent to misrepresent his preference and, after an appropriate redistribution of their shares, each obtain a strictly preferred share. We characterize all bribe-proof rules as the class of efficient, strategy-proof, and weak replacement monotonic rules. In addition, we identify the functional form of all bribe-proof and tops-only rules.

A maximal domain of preferences for tops-only rules in the division problem

The division problem consists of allocating an amount M of a perfectly divisible good among a group of n agents. Sprumont (1991) showed that if agents have single-peaked preferences over their shares, the uniform rule is the unique strategy-proof, efficient, and anonymous rule. Ching and Serizawa (1998) extended this result by showing that the set of single-plateaued preferences is the largest domain, for all possible values of M, admitting a rule (the extended uniform rule) satisfying strategy-proofness, efficiency and symmetry. We identify, for each M and n, a maximal domain of preferences under which the extended uniform rule also satisfies the properties of strategy-proofness, efficiency, continuity, and "tops-onlyness". These domains (called weakly single-plateaued) are strictly larger than the set of single-plateaued preferences. However, their intersection, when M varies from zero to infinity, coincides with the set of single-plateaued preferences.

On Boas-Type Problem

R.P. Boas has found necessary and sufficient conditions of belonging of function to Lipschitz class. From his findings it turned out, that the conditions on sine and cosine coefficients for belonging of function to Lip α(0 & α & 1) are the same, but for Lip 1 are different. Later his results were generalized by many authors in the viewpoint of generalization of condition on the majorant of modulus of continuity. The aim of this paper is to obtain Boas-type theorems for generalized Lipschitz classes. To define generalized Lipschitz classes we use the concept of modulus of smoothness of fractional order.

Normal forms for rational difference equations with applications to the global periodicity problem

We propose a classification and derive the associated normal forms for rational difference equations with complex coefficients. As an application, we study the global periodicity problem for second order rational difference equations with complex coefficients. We find new necessary conditions as well as some new examples of globally periodic equations.