The challenges of curriculum by the integration of ICT in the professional practice of science teacher

The Web has enabled a renewal of the concept of education which includes a new educational model that enables learning anywhere and at any time. The expansion of Internet allows students to have a more active role in the learning process. The curriculum can be (re) build and integrated in an interdisciplinary way. The educational use of ICT in the formal curriculum may be made through collaborative learning processes of interaction and negotiation of meanings, using diverse tools. Regular use of computers and Internet in the classroom allows the development, dissemination and evaluation of student’s achievements. This article describes an ongoing research which included integration of computers and the Internet in the teaching and learning methods and strategies in the disciplines of Biology and Geology in a Portuguese high-school

Algunas consideraciones en torno al significado de la tradición

El concepto "tradición" que desde su origen marcaba la idea de la permanencia de una comunidad en el tiempo ha dejado de ser un sinónimo de un conservadurismo ultramontano; en el ámbito de las ciencias sociales ya no designa las "supersticiones" que obstaculizaban el Progreso; por el contrario, el reciente cuestionamiento frontal de la Ratio y el cuestionamiento del fenómeno de la globalización han contribuido a una revalorización de lo tradicional; así se ve que la tradición es un signo indeleble de la identidad cultural, de lo vernáculo y de la riqueza cultural de la humanidad

From morphology to molecules: A combined source approach to untangle the taxonomy of Clessinia (Gastropoda, Odontostomidae), endemic land snails from the Dry Chaco ecoregion

Background: Land gastropods of the Dry Chaco merit special attention because they comprise a highly diverse but barely studied group. Clessinia Doering, 1875 are typical inhabitants of this ecoregion. The inclusion of their distribution areas into Spixia range, their shell shape similarities, and a former molecular study raised doubts on the monophyly of this genus. The present study review the species of Clessinia, under a morphological, geometric morphometrics, and molecular combined approach. Methods: Adults were collected, photographed, measured, and dissected for anatomical studies. Shell ultrastructure was studied with scanning electron microscope. Geometric morphometric analyses on shells were performed testing if they gave complementary information to anatomy. Two mitochondrial genes, and a nuclear region were studied. Phylogenetic reconstructions to explore the relationships of DNA sequences here obtained to those of Clessinia and Spixia species from GenBank were performed. Results: Species description on shell, periostracal ornamentation and anatomy is provided. We raised former Clessinia cordovana striata to species rank, naming it as Clessinia tulumbensis sp. nov. The periostracum, consisting of hairs and lamellae, has taxonomic importance for species identification. Shell morphometric analyses, inner sculpture of penis and proportion of the epiphallus and penis, were useful tools to species identification. Nuclear markers do not exhibit enough genetic variation to determine species relationships. Based on the mitochondrial markers, genetic distances among Clessinia species were greater than 10%, and while C. cordovana, C. nattkemperi, and C. pagoda were recognized as distinct evolutionary genetic species, the distinction between C. stelzneri and C. tulumbensis sp. nov. was not evident. Clessinia and Spixia were paraphyletic in the molecular phylogenetic analyses. Species of Clessinia here treated have narrow distributional areas and are endemic to the Chaco Serrano subecoregion, restricted to small patches within the Dry Chaco. Clessinia and Spixia are synonymous, and the valid name of the taxon should be Clessinia Doering, 1875 which has priority over Spixia Pilsbry & Vanatta, 1894. Discussion: Our results support the composition of C. cordovana complex by three species, C. cordovana, C. stelzneri, and C. tulumbensis sp. nov. The low genetic divergence between C. stelzneri and C. tulumbensis sp. nov. suggests that they have evolved relatively recently. The former Spixia and Clessinia are externally distinguished because Clessinia has a detached aperture from the body whorl forming a cornet, periostracal microsculpture extended over dorsal portion of the peristome, five inner teeth on the shell aperture instead of three–four found in Spixia. Morphological similarities exists between both genera in shell shape, type of periostracum microsculpture, reproductive anatomy, besides the overlap in geographic ranges.Fil: Cuezzo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; ArgentinaFil: Miranda, Maria Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; ArgentinaFil: Vogler, Roberto Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Universidad Nacional de Misiones. Instituto de Biología Subtropical; ArgentinaFil: Beltramino, Ariel Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Universidad Nacional de Misiones. Instituto de Biología Subtropical; Argentin

Utility Stock Splits: Signaling Motive Versus Liquidity Motive

Despite the rich literature on theories of stock splits, studies have omitted public utility firms from their analysis and only analyzed split by industrial firms when examining managerial motives for splitting their stock. I examine the liquidity-marketability hypothesis, which states that stock splits enhance the attractiveness of shares to individual investors and increase trading volume by adjusting prices to an optimum trading range. Changes in the regulatory process, resulting from EPACT, have opened a window of opportunity for the study and comparison of the two traditional motives for splitting stock --signaling versus liquidity-marketability motives. Public electric utility firms provide a clean testing ground for these two non-mutually exclusive theories as liquidity/marketability hypothesis should dominate before the enactment of the EPACT since the conventional signaling theory of common stock splits should not apply given the low levels of information asymmetry in regulated utility companies. In the post-EPACT period, however, the signaling effect is expected to play a more dominant role. Based on both univariate and multivariate analyses, my results are consistent with the hypothesis posed. For the pre-EPACT period, liquidity motive seems to predominate in explaining the abnormal announcement return of utility stock splits. On the other hand, the results support the signaling motive as a leading explanation of abnormal returns in the post-EPACT period

Bostryx tortoranus (Doering, 1879) species complex (Gastropoda: Stylommatophora: Bulimulidae), a review of taxonomy and distribution of endemic species from Argentina

Morphology of the shell, radula, jaw, anatomy and sculpture of the inner wall of the reproductive system are described and compared for three species belonging to the Bostryx tortoranus species complex. On the basis of these characters, the following changes are proposed: Bostryx martinezi (Hylton Scott, 1965) is removed from synonymy with Bostryx tortoranus (Doering, 1879) and Bulimulus (Scansicochlea) cicheroi Hylton Scott, 1967 is transferred from synonymy with B. tortoranus to synonymy with B. martinezi. As a result of these changes, the number of species of Bostryx known from Argentina has increased to 19 species. Bostryx tortoranus and B. martinezi are redescribed, also the radula and anatomy of Bostryx rudisculptus (Parodiz, 1956) are described for the first time. The main distinctive morphological characters of the three species are: the structure of the shell’s protoconch and teleoconch, radular morphology, location of the secondary ureter opening, the length of the free oviduct with respect to the vagina and the epiphallus with respect to the penis and the bursa copulatrix duct’s inner wall sculpture. Bostryx martinezi and B. rudisculptus have restricted distributions and are ecologically endemic, whereas B. tortoranus has a wide distribution and is located in different dry ecoregions.Fil: Miranda, Maria Jose. Universidad Nacional de Tucuman. Facultad de Cs.naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

A mechanistic study on the phototoxicity of atorvastatin: singlet oxygen generation by a phenanthrene-like photoproduct

Atorvastatin calcium (ATV) is one of the most frequently prescribed drugs worldwide. Among the adverse effects observed for this lipid-lowering agent, clinical cases of cutaneous adverse reactions have been reported and associated with photosensitivity disorders. Previous work dealing with ATV photochemistry has shown that exposure to natural sunlight in aqueous solution leads to photoproducts resulting from oxidation of the pyrrole ring and from cyclization to a phenanthrene derivative. Laser flash photolysis of ATV, at both 266 and 308 nm, led to a transient spectrum with two maxima at λ ) 360 and λ ) 580 nm (τ ) 41 μs), which was assigned to the primary intermediate of the stilbene-like photocyclization. On the basis of the absence of a triplet-triplet absorption, the role of the parent drug as singlet oxygen photosensitizer can be discarded. By contrast, a stable phenanthrene-like photoproduct would be a good candidate to play this role. Laser flash photolysis of this compound showed a triplet-triplet transient absorption at λmax ) 460 nm with a lifetime of 26 μs, which was efficiently quenched by oxygen (kq ) 3 ((0.2) × 109 M-1 s-1). Its potential to photosensitize formation of singlet oxygen was confirmed by spin trapping experiments, through conversion of TEMP to the stable free radical TEMPO. The photoreactivity of the phenanthrene-like photoproduct was investigated using Trp as a marker. The disappearance of the amino acid fluorescence (λmax ) 340 nm) after increasing irradiation times at 355 nm was taken as a measurement of photodynamic oxidation. To confirm the involvement of a type II mechanism, the same experiment was also performed in D2O; this resulted in a significant enhancement of the reaction rate. On the basis of the obtained photophysical and photochemical results, the phototoxicity of atorvastatin can be attributed to singlet oxygen formation with the phenanthrene-like photoproduct as a photosensitizer