Using social networking tools for teaching and learning: a perspective of University lecturers and students

The use of online social networking tools (SNTs) has become commonplace within higher education. In this paper a definition and a typology of educational affordance of social networking service (SNS) are presented. The paper also explores the educational affordances whilst examining how university lecturers and students use SNTs to support their educational activities. The data presented here were obtained through a survey in which 38 participants from three universities took part; two universities in Uganda and one in the United Kingdom. The results show that Facebook is the most popular tool with 75 % of participants having profiles. Whilst most participants perceived the educational significance of these tools, social affordances remain more pronounced compared to pedagogical and technological affordances. The limitations of this study have also been discussed.

Students’ perception of privacy risks in using social networking sites for learning: a study of Uganda Christian University

Although social networking sites (SNSs) present a great deal of opportunities to support learning, the privacy risk is perceived by learners as a friction point that affects their full use for learning. Privacy risks in SNSs can be divided into risks that are posed by the SNS provider itself and risks that result from user’s social interactions. Using an online survey questionnaire, this study explored the students’ perception of the benefits in using social networking sites for learning purposes and their perceived privacy risks. A sample of 214 students from Uganda Christian University in Africa was studied. The results show that although 88 % of participants indicated the usefulness of SNSs for learning, they are also aware of the risks associated with these sites. Most of the participants are concerned with privacy risks such as identity theft, cyber bullying, and impersonation that might influence their online learning participation in SNSs.

Different strategies for improving summer thermal comfort in heavyweight traditional buildings

In order to exploit the passive energy potential of the building envelope, it is important to provide a right combination of insulation thickness, heat capacity and night-time ventilation. In this paper, this issue will be tackled with reference to an historic building in Catania (Southern Italy). The building was built at the end of the XIX century, and its opaque envelope is entirely made with lava stones, which is typical of traditional architecture in this area. Starting from the current configuration of the building, many hypotheses for refurbishment are considered, combined with different strategies for passive cooling, such as night-time ventilation, use of shading devices and adoption of highly-reflective coatings. The effectiveness of each solution in terms of summer thermal comfort is evaluated through dynamic thermal simulations carried out with EnergyPlus. The results show the synergic effect of these strategies, as well as their individual impact, and allow to draw some general conclusions about the behaviour of heavyweight buildings under moderately hot weather conditions.

Histological Outcomes on the Development of New Space-making Devices for Maxillary Sinus Floor Augmentation

Background: Previous studies have pointed out that the mere elevation of the maxillary sinus membrane promotes bone formation without the use of augmentation materials. Purpose: This experimental study aimed at evaluating if the two-stage procedure for sinus floor augmentation could benefit from the use of a space-making device in order to increase the bone volume to enable later implant installation with good primary stability. Materials and Methods: Six male tufted capuchin primates (Cebus apella) were subjected to extraction of the three premolars and the first molar on both sides of the maxilla to create an edentulous area. The sinuses were opened using the lateral bone-wall window technique, and the membrane was elevated. One resorbable space-making device was inserted in each maxillary sinus, and the bone window was returned in place. The animals were euthanatized after 6 months, and biopsy blocks containing the whole maxillary sinus and surrounding soft tissues were prepared for ground sections. Results: The histological examination of the specimens showed bone formation in contact with both the schneiderian membrane and the device in most cases even when the device was displaced. The process of bone formation indicates that this technique is potentially useful for two-stage sinus floor augmentation. The lack of stabilization of the device within the sinus demands further improvement of space-makers for predictable bone augmentation. Conclusions: It is concluded that (1) the device used in this study did not trigger any important inflammatory reaction; (2) when the sinus membrane was elevated, bone formation was a constant finding; and (3) an ideal space-making device should be stable and elevate the membrane to ensure a maintained connection between the membrane and the secluded space.

Geophysical investigation using resistivity and GPR methods: a case study of a lubricant oil waste disposal area in the city of Ribeiro Preto, So Paulo, Brazil

Geophysics has been shown to be effective in identifying areas contaminated by waste disposal, contributing to the greater efficiency of soundings programs and the installation of monitoring wells. In the study area, four trenches were constructed with a total volume of about 25,000 m(3). They were almost totally filled with re-refined lubricating oil waste for approximately 25 years. No protection liners were used in the bottoms and laterals of the disposal trenches. The purpose of this work is to evaluate the potential of the resistivity and ground penetrating radar (GPR) methods in characterizing the contamination of this lubricant oil waste disposal area in Ribeiro Preto, SP, situated on the geological domain of the basalt spills of the Serra Geral Formation and the sandstones of the Botucatu Formation. Geophysical results were shown in 2D profiles. The geophysical methods used enabled the identification of geophysical anomalies, which characterized the contamination produced by the trenches filled with lubricant oil waste. Conductive anomalies (smaller than 185 Omega m) immediately below the trenches suggest the action of bacteria in the hydrocarbons, as has been observed in several sites contaminated by hydrocarbons in previously reported cases in the literature. It was also possible to define the geometry of the trenches, as evidenced by the GPR method. Direct sampling (chemical analysis of the soil and the water in the monitoring well) confirmed the contamination. In the soil analysis, low concentrations of several polycyclic aromatic hydrocarbons (PAHs) were found, mainly naphthalene and phenanthrene. In the water samples, an analysis verified contamination of the groundwater by lead (Pb). The geophysical methods used in the investigation provided an excellent tool for environmental characterization in this study of a lubricant oil waste disposal area, and could be applied in the study of similar areas.

Craniometaphyseal Dysplasia With Severe Craniofacial Involvement Shows Homozygosity at 6q21-22.1 Locus

Craniotubular dysplasias (CTD) are a heterogeneous group of genetic disorders of skeletal development, whose clinical and etiological classification is still much debated. One of the most common form is the autosomal dominant craniometaphyseal dysplasia (CMD) which is associated with mutation in the ANKH gene. In the literature a few families are reported with CMD phenotype that suggest an autosomal recessive (AR) pattern of inheritance. A candidate locus at 6q21-22 has been mapped in a large inbred Brazilian family, but the gene of the recessive form is still unknown. Our data on a female patient with CMD phenotype, born from healthy first degree cousins and displaying homozygosity for polymorphic markers at the 6q21-22 locus, further support the existence of an AR CMD, expanding its clinical spectrum to a more severe phenotype. (C) 2011 Wiley-Liss, Inc.

Screening of ARHSP-TCC Patients Expands the Spectrum of SPG11 Mutations and Includes a Large Scale Gene Deletion

Autosomal recessive spastic paraplegia with thinning of corpus callosum (ARHSP-TCC) is a complex form of HSP initially described in Japan but subsequently reported to have a worldwide distribution with a particular high frequency in multiple families from the Mediterranean basin. We recently showed that ARHSP-TCC is commonly associated with mutations in SPG11/KIAA1840 on chromosome 15q. We have now screened a collection of new patients mainly originating from Italy and Brazil, in order to further ascertain the spectrum of mutations in SPG11, enlarge the ethnic origin of SPG11 patients, determine the relative frequency at the level of single Countries (i.e., Italy), and establish whether there is one or more common mutation. In 25 index cases we identified 32 mutations; 22 are novel, including 9 nonsense, 3 small deletions, 4 insertions, 1 in/del, 1 small duplication, 1 missense, 2 splice-site, and for the first time a large genomic rearrangement. This brings the total number of SPG11 mutated patients in the SPATAX collection to 111 cases in 44 families and in 17 isolated cases, from 16 Countries, all assessed using homogeneous clinical criteria. While expanding the spectrum of mutations in SPG11, this larger series also corroborated the notion that even within apparently homogeneous population a molecular diagnosis cannot be achieved without full gene sequencing. (C) 2008 Wiley-Liss, Inc.

Comparing machine learning classifiers in potential distribution modelling

Species` potential distribution modelling consists of building a representation of the fundamental ecological requirements of a species from biotic and abiotic conditions where the species is known to occur. Such models can be valuable tools to understand the biogeography of species and to support the prediction of its presence/absence considering a particular environment scenario. This paper investigates the use of different supervised machine learning techniques to model the potential distribution of 35 plant species from Latin America. Each technique was able to extract a different representation of the relations between the environmental conditions and the distribution profile of the species. The experimental results highlight the good performance of random trees classifiers, indicating this particular technique as a promising candidate for modelling species` potential distribution. (C) 2010 Elsevier Ltd. All rights reserved.

Magnetic linear dichroism in absorption spectroscopy of EuTe

The magnetic linear dichroism (MLD) at band-edge photon energies in the Voigt geometry was calculated for EuTe. At the spin-flop transition, MLD shows a step-like increase. Above the spin-flop transition MLD slowly decreases and becomes zero when the averaged electronic charge becomes symmetric relative to the axis of light propagation. Further increase of the magnetic field causes ferromagnetic alignment of the spins along the magnetic field direction, and MLD is recovered but with an opposite sign, and reaches maximum absolute values. These results are explained by the rearrangement of the Eu(2+) spin distribution in the crystal lattice as a function of magnetic field, due to the Zeeman interaction, demonstrating that MLD can be a sensitive probe of the spin order in EuTe, and provides information that is not accessible from other magneto-optical techniques, such as magnetic circular dichroism measurement studies.

Synthesis of L1(0) Fe-Pd films by electrodeposition and thermal annealing

Fe-Pd alloy films have been prepared by electrochemical deposition from an alkaline electrolyte containing Fe sulfate, Pd chloride and 5-sulfosalicylic acid onto polycrystalline titanium substrates. The as-deposited films were nanocrystalline and magnetically soft (coercivity similar to 25 Oe). L1(0) Fe-Pd films with a (111) preferred orientation were obtained by post-deposition thermal annealing of films with composition about 37 at% Fe in an (Ar + 5% H-2) gas flow at 500 degrees C. Such films exhibit hard magnetic properties, with a coercivity up to 1880 Oe, and a slightly anisotropic magnetic response, with a larger in-plane remanence. Preliminary magnetic investigations support magnetization switching through pinning of domain walls. (c) 2008 Elsevier B.V. All rights reserved.

Oxindole-Schiff base copper(II) complexes interactions with human serum albumin: Spectroscopic, oxidative damage, and computational studies

CD and EPR were used to characterize interactions of oxindole-Schiff base copper(II) complexes with human serum albumin (HSA). These imine ligands form very stable complexes with copper, and can efficiently compete for this metal ion towards the specific N-terminal binding site of the protein, consisting of the amino acid sequence Asp-Ala-His. Relative stability constants for the corresponding complexes were estimated from CD data, using the protein as competitive ligand, with values of log K(CuL) in the range 15.7-18.1, very close to that of [Cu(HSA)] itself, with log K(CuHSA) 16.2. Some of the complexes are also able to interfere in the a-helix structure of the protein, while others seem not to affect it. EPR spectra corroborate those results, indicating at least two different metal species in solution, depending on the imine ligand. Oxidative damage to the protein after incubation with these copper(II) complexes, particularly in the presence of hydrogen peroxide, was monitored by carbonyl groups formation, and was observed to be more severe when conformational features of the protein were modified. Complementary EPR spin-trapping data indicated significant formation of hydroxyl and carbon centered radicals, consistent with an oxidative mechanism. Theoretical calculations at density functional theory (DFT) level were employed to evaluate Cu(II)-L binding energies, L -> Cu(II) donation, and Cu(II) -> L back-donation, by considering the Schiff bases and the N-terminal site of HSA as ligands. These results complement previous studies on cytotoxicity, nuclease and pro-apoptotic properties of this kind of copper(II) complexes, providing additional information about their possibilities of transport and disposition in blood plasma. (C) 2009 Elsevier Inc. All rights reserved.

Um Modelo de estruturação de requisitos para o método fusion

Uma definição confiável dos requisitos de um software depende diretamente da completa e correta compreensão sobre as necessidades do sistema e sua conseqüente representação de forma adequada ao processo de desenvolvimento. Uma proposta de modelagem de requisitos deve apresentar qualidades que colaborem para a compreensão mútua das necessidades entre os envolvidos no processo e que organizem os requisitos de forma a permitir o acompanhamento no desenvolvimento do software. O presente trabalho apresenta um modelo de estruturação de requisitos fundamentado em metodologias orientadas a objetivos com utilização de cenários e preceitos da Teoria da Atividade. O modelo tem sua argumentação nas premissas que cliente e usuários normalmente expressam suas necessidades através de objetivos almejados e que a ação humana deve ser analisada dentro de um contexto para que possa fazer sentido e ser compreendida. Inserido no contexto do Projeto FILM1, cujo objetivo é expandir o Método Fusion, agregando uma etapa de modelagem de requisitos, o trabalho estabeleceu a qualidade de usabilidade como motivadora da definição de um modelo de estruturação de requisitos. A usabilidade é uma qualidade que visa facilitar a utilização do modelo como uma ferramenta de representação dos requisitos de forma inteligível, atuando tanto na especificação dos requisitos como na validação dos mesmos entre os envolvidos. Os requisitos são estruturados segundo uma abordagem voltada aos clientes e usuários do sistema. O modelo definido tem por objetivo prover a construção gradual e incremental do entendimento compartilhado entre os envolvidos sobre os domínios do problema e da solução, na concepção e no desenvolvimento do software. Metodologias orientadas a objetivos, operacionalizadas através de cenários, conjugadas a princípios da atividade oferecem um suporte adequado a estruturação de requisitos provendo usabilidade ao modelo. A avaliação da aplicabilidade do modelo é realizada com a modelagem de requisitos em três estudos de casos. Em cada caso são aplicadas técnicas de elicitação no sentido da afinar a sintonia com a estrutura do modelo de requisitos. A concepção do modelo, embasada em conceitos da Teoria da Atividade, é bastante adequado às atividades de elicitação em uma abordagem voltada aos clientes e usuários.

Trade liberalization and industrial concentration: evidence from Brazil

This paper applies an endogenous lobby formation model to explain the extent of trade protection granted to Brazilian manufacturing industries during the 1988- 1994 trade liberalization episode. Using a panel data set covering this period, we find that even in an environment in which a major regime shift has been introduced, more concentrated sectors have been able to obtain policy advantages, that lead to a reduction in international competition. The importance of industry structure appears to be substantial: In our baseline specification, an increase in concentration by 20% leads to an increase in protection by 5%-7%.