Moodle and multiple-choice tests

Multiple-Choice items are used in many different kinds of tests in several areas of knowledge. They can be considered an interesting tool to the self-assessing or as an alternative or complementary instrument to the traditional methods for assessing knowledge. The objectivity and accuracy of the multiple-choice tests is an important reason to think about. They are especially useful when the number of students to evaluate is too large. Moodle (Modular Object-Oriented Dynamic Learning Environment) is an Open Source course management system centered around learners' needs and designed to support collaborative approaches to teaching and learning. Moodle offers to the users a rich interface, context-specific help buttons, and a wide variety of tools such as discussion forums, wikis, chat, surveys, quizzes, glossaries, journals, grade books and more, that allow them to learn and collaborate in a truly interactive space. Come together the interactivity of the Moodle platform and the objectivity of this kind of tests one can easily build manifold random tests. The proposal of this paper is to relate our journey in the construction of these tests and share our experience in the use of the Moodle platform to create, take advantage and improve the multiple-choices tests in the Mathematic area.

Augmented LDPC Graph for Distributed Video Coding with Multiple Side Information

The advances made in channel-capacity codes, such as turbo codes and low-density parity-check (LDPC) codes, have played a major role in the emerging distributed source coding paradigm. LDPC codes can be easily adapted to new source coding strategies due to their natural representation as bipartite graphs and the use of quasi-optimal decoding algorithms, such as belief propagation. This paper tackles a relevant scenario in distributedvideo coding: lossy source coding when multiple side information (SI) hypotheses are available at the decoder, each one correlated with the source according to different correlation noise channels. Thus, it is proposed to exploit multiple SI hypotheses through an efficient joint decoding technique withmultiple LDPC syndrome decoders that exchange information to obtain coding efficiency improvements. At the decoder side, the multiple SI hypotheses are created with motion compensated frame interpolation and fused together in a novel iterative LDPC based Slepian-Wolf decoding algorithm. With the creation of multiple SI hypotheses and the proposed decoding algorithm, bitrate savings up to 8.0% are obtained for similar decoded quality.

On the use of IEEE 802.15.4/Zigbee for time-sensitive wireless sensor network applications

Mestrado em Engenharia Electrotécnica e de Computadores

Mapping multi-species habitat use for marine conservation planning

Tese de Doutoramento, Ciências do Mar (Biologia Marinha)

Helmet use among motorcyclists: observational study in the city of Mar del Plata, Argentina

The objective of the study was to assess the use of helmets in a community where helmet use is mandatory but low as there is no police enforcement. A sample comprising 451 motorcyclists in the city of Mar del Plata, Argentina, was studied in 2006. The following variables were studied: gender, type of motorcycle, weather conditions, time of the day, city area and type of road where motorcyclists traveled. Data were analyzed through a multiple logistic regression model. An overall 40% prevalence (95% CI: 35.5;44.5) of helmet use was found. Higher rates of helmet use were seen among women, and under unfavorable weather conditions, lower rates were found in the city outskirts, and variable use was seen according to the type of motorcycle. There is a need to improve law enforcement and to promote education of motorcyclists.

HIV/AIDS risk among female sex workers who use crack in Southern Brazil

OBJECTIVE: To understand the social context of female sex workers who use crack and its impact on HIV/AIDS risk behaviors. METHODODOLOGICAL PROCEDURES: Qualitative study carried out in Foz do Iguaçu, Southern Brazil, in 2003. Twenty-six in-depth interviews and two focus groups were carried out with female commercial sex workers who frequently use crack. In-depth interviews with health providers, community leaders and public policy managers, as well as field observations were also conducted. Transcript data was entered into Atlas.ti software and grounded theory methodology was used to analyze the data and develop a conceptual model as a result of this study. ANALYSIS OF RESULTS: Female sex workers who use crack had low self-perceived HIV risk in spite of being engaged in risky behaviors (e.g. unprotected sex with multiple partners). Physical and sexual violence among clients, occasional and stable partners was widespread jeopardizing negotiation and consistent condom use. According to health providers, community leaders and public policy managers, several female sex workers who use crack are homeless or live in slums, and rarely have access to health services, voluntary counseling and testing, social support, pre-natal and reproductive care. CONCLUSIONS: Female sex workers who use crack experience a plethora of health and social problems, which apparently affect their risks for HIV infection. Low-threshold, user-friendly and gender-tailored interventions should be implemented, in order to increase the access to health and social-support services among this population. Those initiatives might also increase their access to reproductive health in general, and to preventive strategies focusing on HIV/AIDS and other sexually transmitted infections.

Use of solvent extraction to remediate soils contaminated with hydrocarbons

The main objective of this research is to exploit the possibility of using an ex situ solvent extraction technique for the remediation of soils contaminated with semi-volatile petroleum hydrocarbons. The composition of the organic phase was chosen in order to form a single phase mixture with an aqueous phase and simultaneously not being disturbed (forming stable emulsions) by the soil particles hauling the contaminants. It should also permit a regeneration of the organic solvent phase. As first, we studied the miscibility domain of the chosen ternary systems constituted by ethyl acetate–acetone–water. This system proved to satisfy the previous requirements allowing for the formation of a single liquid phase mixture within a large spectrum of compositions, and also allowing for an intimate contact with the soil. Contaminants in the diesel range within different functional groups were selected: xylene, naphthalene and hexadecane. The analytical control was done by gas chromatography with FID detector. The kinetics of the extractions proved to be fast, leading to equilibrium after 10 min. The effect of the solid–liquid ratio on the extraction efficiency was studied. Lower S/L ratios (1:8, w/v) proved to be more efficient, reaching recoveries in the order of 95%. The option of extraction in multiple contacts did not improve the recovery in relation to a single contact. The solvent can be regenerated by distillation with a loss around 10%. The contaminants are not evaporated and they remain in the non-volatile phase. The global results show that the ex situ solvent extraction is technically a feasible option for the remediation of semi-volatile aromatic, polyaromatic and linear hydrocarbons.

Drug use in college students: a 13-year trend

OBJECTIVE: To analyze drug use trends among college students in 1996, 2001 and 2009. METHODS: A cross-sectional epidemiological study with a multistage stratified cluster sample with 9,974 college students was conducted in the city of São Paulo, southeastern Brazil. An anonymous self-administered questionnaire was used to collect information on drug use assessed in lifetime, the preceding 12 months and the preceding 30 days. The Bonferroni correction was used for multiple comparisons of drug use rates between surveys. RESULTS: There were changes in the lifetime use of tobacco and some other drugs (hallucinogens [6.1% to 8.8%], amphetamines [4.6% to 8.7%], and tranquilizers [5.7% to 8.2%]) from 1996 to 2009. Differences in the use of other drugs over the 12 months preceding the survey were also seen: reduced use of inhalants [9.0% to 4.8%] and increased use of amphetamines [2.4% to 4.8%]. There was a reduction in alcohol [72.9% to 62.1%], tobacco [21.3% to 17.2%] and marijuana [15.0% to 11.5%] use and an increase in amphetamine use [1.9% to 3.3%] in the preceeding 30 days. CONCLUSIONS: Over the 13-year study period, there was an increase in lifetime use of tobacco, hallucinogens, amphetamines, and tranquilizers. There was an increase in amphetamine use and a reduction in alcohol use during the preceding 12 months. There was an increase in amphetamine use during the preceding 30 days.

Static-priority scheduling over wireless networks with multiple broadcast domains

We propose a wireless medium access control (MAC) protocol that provides static-priority scheduling of messages in a guaranteed collision-free manner. Our protocol supports multiple broadcast domains, resolves the wireless hidden terminal problem and allows for parallel transmissions across a mesh network. Arbitration of messages is achieved without the notion of a master coordinating node, global clock synchronization or out-of-band signaling. The protocol relies on bit-dominance similar to what is used in the CAN bus except that in order to operate on a wireless physical layer, nodes are not required to receive incoming bits while transmitting. The use of bit-dominance efficiently allows for a much larger number of priorities than would be possible using existing wireless solutions. A MAC protocol with these properties enables schedulability analysis of sporadic message streams in wireless multihop networks.

Access to continued-use medication among older adults, Brazil

OBJECTIVE To determine the prevalence and associated access factors for all continued-use prescription drugs and the ways in which they can be obtained.METHODS Data was obtained from the 2008 Household National Survey. The sample comprised 27,333 individuals above 60 years who reported that they used continued-use prescription drugs. A descriptive analysis and binary and multiple multinomial logistic regressions were performed.RESULTS 86.0% of the older adults had access to all the medication they needed, and among them, 50.7% purchased said medication. Those who obtained medication from the public health system were younger (60-64 years), did not have health insurance plans, and belonged to the lower income groups. It is remarkable that 14.0% of the subjects still had no access to any continued-use medication, and for those with more than four chronic diseases, this amount reached 22.0%. Those with a greater number of chronic diseases ran a higher risk of not having access to all the medication they needed.CONCLUSIONS There are some groups of older adults with an increased risk of not obtaining all the medication they need and of purchasing it. The results of this study are expected to contribute to guide programs and plans for access to medication in Brazil.

The extended unsymmetric frontal solution for multiple-point constraints

The purpose of this paper is to discuss the linear solution of equality constrained problems by using the Frontal solution method without explicit assembling. Design/methodology/approach - Re-written frontal solution method with a priori pivot and front sequence. OpenMP parallelization, nearly linear (in elimination and substitution) up to 40 threads. Constraints enforced at the local assembling stage. Findings - When compared with both standard sparse solvers and classical frontal implementations, memory requirements and code size are significantly reduced. Research limitations/implications - Large, non-linear problems with constraints typically make use of the Newton method with Lagrange multipliers. In the context of the solution of problems with large number of constraints, the matrix transformation methods (MTM) are often more cost-effective. The paper presents a complete solution, with topological ordering, for this problem. Practical implications - A complete software package in Fortran 2003 is described. Examples of clique-based problems are shown with large systems solved in core. Social implications - More realistic non-linear problems can be solved with this Frontal code at the core of the Newton method. Originality/value - Use of topological ordering of constraints. A-priori pivot and front sequences. No need for symbolic assembling. Constraints treated at the core of the Frontal solver. Use of OpenMP in the main Frontal loop, now quantified. Availability of Software.

EPIDEMIOLOGICAL SURVEY ON CANINE POPULATION WITH THE USE OF IMMUNOLEISH SKIN TEST IN ENDEMIC AREAS OF HUMAN AMERICAN CUTANEOUS LEISHMANIASIS IN THE STATE OF RIO DE JANEIRO, BRAZIL

A survey for canine tegumentary leishmaniasis (CTL) has been carried out between 1986 and 1993 in seven endemic localities for American cutaneous leishmaniasis in the State of Rio de Janeiro. 270 dogs have been examined for their clinical aspects, the development of delayed hypersensitivity (DHS) with Immunoleish antigen and with immunofluorescent antibody research of IgG (IF). 28.2% of them had ulcer lesions and 3.3% had scars. The lesions consisted of single (39.5%) and mucocutaneous lesions (31.6%), multiple cutaneous (25.0%) and mucocutaneous lesions associated with cutaneous ulcers (4.0%). Twelve (15.8%) isolates from biopsies were analyzed by zimodeme and schizodeme and identified as L. (V.) braziliensis. The overall prevalence of canine infection that was evaluated with the skin test was of 40.5% and with IF it was of 25.5%. Both tests showed a high positive rate with relation to the animals with mucosal lesions, as in the case of human mucocutaneous leishmaniasis. The comparison of the two tests showed the skin test to have a better performance although there was no statistical difference (p>0.05) between them. The proportional sensitivity and specificity was of 84.0% and 74.0%, respectively. The Immunoleish skin test and IF are useful tools to be employed in CTL field epidemiological surveys.

Coordinated Maneuver for Gradient Search Using Multiple AUV's

OCEANS 2003. Proceedings (Volume:1 )

Testing Nelder-Mead Based Repulsion Algorithms for Multiple Roots of Nonlinear Systems via a Two-Level Factorial Design of Experiments

This paper addresses the challenging task of computing multiple roots of a system of nonlinear equations. A repulsion algorithm that invokes the Nelder-Mead (N-M) local search method and uses a penalty-type merit function based on the error function, known as 'erf', is presented. In the N-M algorithm context, different strategies are proposed to enhance the quality of the solutions and improve the overall efficiency. The main goal of this paper is to use a two-level factorial design of experiments to analyze the statistical significance of the observed differences in selected performance criteria produced when testing different strategies in the N-M based repulsion algorithm. The main goal of this paper is to use a two-level factorial design of experiments to analyze the statistical significance of the observed differences in selected performance criteria produced when testing different strategies in the N-M based repulsion algorithm.

A Multiple Criteria Utility-based Approa h for the Unit Commitment with Wind Power and Pumped Storage Hydro

The integration of wind power in eletricity generation brings new challenges to unit commitment due to the random nature of wind speed. For this particular optimisation problem, wind uncertainty has been handled in practice by means of conservative stochastic scenario-based optimisation models, or through additional operating reserve settings. However, generation companies may have different attitudes towards operating costs, load curtailment, or waste of wind energy, when considering the risk caused by wind power variability. Therefore, alternative and possibly more adequate approaches should be explored. This work is divided in two main parts. Firstly we survey the main formulations presented in the literature for the integration of wind power in the unit commitment problem (UCP) and present an alternative model for the wind-thermal unit commitment. We make use of the utility theory concepts to develop a multi-criteria stochastic model. The objectives considered are the minimisation of costs, load curtailment and waste of wind energy. Those are represented by individual utility functions and aggregated in a single additive utility function. This last function is adequately linearised leading to a mixed-integer linear program (MILP) model that can be tackled by general-purpose solvers in order to find the most preferred solution. In the second part we discuss the integration of pumped-storage hydro (PSH) units in the UCP with large wind penetration. Those units can provide extra flexibility by using wind energy to pump and store water in the form of potential energy that can be generated after during peak load periods. PSH units are added to the first model, yielding a MILP model with wind-hydro-thermal coordination. Results showed that the proposed methodology is able to reflect the risk profiles of decision makers for both models. By including PSH units, the results are significantly improved.