2,099 research outputs found
Os Sistemas Apícolas e a Agricultura Familiar: um estudo de caso sobre a Cooperativa de Apicultores de Canguçu (COOMELCA), município de Canguçu, RS.
Dissertação (Mestrado) - Programa de Pós-Graduação em Sistemas de Produção Agrícola Familiar. Faculdade de Agronomia Eliseu Maciel. Universidade Federal de Pelotas, Pelotas, 2017. Orientador: Antônio Jorge Amaral Bezerra, Co-orientador: Luis Fernando Wolff, CPACT
Design, Implementation and Evaluation of PsyWeb, a Learning Environment in a Problem Based Learning Curriculum.
In this article we describe the design and implementation of PsyWeb, a rich learning environment for the new problem based study in Psychology at Erasmus University Rotterdam Experiences are reported for the first five (of eight) courses of the first year of the new study. Students opinions have been collected as part of a survey at the end of each course. Results indicate that students are positive about PsyWeb. The overall appreciation shows a slight increase over time. Starting with the second course, usage of PsyWeb has been logged. Usage has been quantified in terms of the number of unique IP-addresses per day. Using this measure we assume that PsyWeb has a student reach between 25% and 100% per day. Usage shows a slight increase over the courses. The implementation of a series of additions to PsyWeb has been planned for the next year
Random tree growth by vertex splitting
We study a model of growing planar tree graphs where in each time step we
separate the tree into two components by splitting a vertex and then connect
the two pieces by inserting a new link between the daughter vertices. This
model generalises the preferential attachment model and Ford's -model
for phylogenetic trees. We develop a mean field theory for the vertex degree
distribution, prove that the mean field theory is exact in some special cases
and check that it agrees with numerical simulations in general. We calculate
various correlation functions and show that the intrinsic Hausdorff dimension
can vary from one to infinity, depending on the parameters of the model.Comment: 47 page
Storage of correlated patterns in a perceptron
We calculate the storage capacity of a perceptron for correlated gaussian
patterns. We find that the storage capacity can be less than 2 if
similar patterns are mapped onto different outputs and vice versa. As long as
the patterns are in general position we obtain, in contrast to previous works,
that in agreement with Cover's theorem. Numerical simulations
confirm the results.Comment: 9 pages LaTeX ioplppt style, figures included using eps
Fijnstofemissie uit stallen: (groot)ouderdieren van vleeskuikens = Dust emission from animal houses: broiler breeders
In this study emissions of fine dust (PM10 and PM2.5) from houses for broiler breeders were determined. In addition, emissions of ammonia, greenhouse gases and odour were determine
Herschel Survey of Galactic OH+, H2O+, and H3O+: Probing the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate
In diffuse interstellar clouds the chemistry that leads to the formation of
the oxygen bearing ions OH+, H2O+, and H3O+ begins with the ionization of
atomic hydrogen by cosmic rays, and continues through subsequent hydrogen
abstraction reactions involving H2. Given these reaction pathways, the observed
abundances of these molecules are useful in constraining both the total
cosmic-ray ionization rate of atomic hydrogen (zeta_H) and molecular hydrogen
fraction, f(H2). We present observations targeting transitions of OH+, H2O+,
and H3O+ made with the Herschel Space Observatory along 20 Galactic sight lines
toward bright submillimeter continuum sources. Both OH+ and H2O+ are detected
in absorption in multiple velocity components along every sight line, but H3O+
is only detected along 7 sight lines. From the molecular abundances we compute
f(H2) in multiple distinct components along each line of sight, and find a
Gaussian distribution with mean and standard deviation 0.042+-0.018. This
confirms previous findings that OH+ and H2O+ primarily reside in gas with low
H2 fractions. We also infer zeta_H throughout our sample, and find a log-normal
distribution with mean log(zeta_H)=-15.75, (zeta_H=1.78x10^-16 s^-1), and
standard deviation 0.29 for gas within the Galactic disk, but outside of the
Galactic center. This is in good agreement with the mean and distribution of
cosmic-ray ionization rates previously inferred from H3+ observations.
Ionization rates in the Galactic center tend to be 10--100 times larger than
found in the Galactic disk, also in accord with prior studies.Comment: 76 pages, 25 figures, 6 tables; accepted for publication in Ap
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