Transmission loss allocation through equivalent bilateral exchanges and economical analysis

A new loss allocation (LA) scheme based on the principle of equivalent bilateral exchanges (EBEs) is presented and compared with other available techniques. Formulation and results from extensive simulations including consistency tests show that the suggested methodology has several desirable properties: It is flow-based, requiring only a solved load flow for its implementation; it is not dependent on the choice of a slack bus; it is straightforward to apply; undesirable negative loss allocation is not produced; and low volatilities are shaped. An economic analysis with various LA methods is also carried out when these are integrated into a combined economic dispatch/load flow dispatch strategy, a likely scenario for LA in a real system. This combined dispatch strategy yields prices charged to the loads and rates received by the generators that account for loss allocation and loss supply. Results show that these economic indexes are very close to the marginal costs derived from an optimal power flow (OPF) approach with the advantage of reducing volatility.     

Nephelometric study of salivary protein–tannin aggregates

Grape seed procyanidins were fractionated through different degrees of polymerisation, and human saliva was purified and separated into two fractions: one was mostly α‐amylase and the other was essentially proline‐rich proteins (PRPs). The interaction of these proteins with the procyanidin compounds was assayed using nephelometry, and the influence of several factors was investigated, such as degree of polymerisation, pH and concentrations of both protein and tannin. The same experiments were performed with bovine serum albumin (BSA). The amount of insoluble aggregates, resulting from the formation of polyphenol–protein aggregates, increased quickly up to a maximum value which thereafter remained practically unchanged. pH was set at 5.0 for all further assays, since it was the nearest value to that encountered in human saliva (pH 5.6–7.9), where proteins were stable and had a maximum ability to bind and precipitate procyanidin oligomers. These proteins were shown to have a strong affinity for procyanidin oligomers and were unable to resolubilise the polyphenol–protein aggregates when present in excess. PRPs required a much lower content to bind all the tannins (400 µg of procyanidin oligomers) than BSA and especially α‐amylase (48, 60 and 132 µg respectively). The procyanidin's ability to bind PRPs, BSA and α‐amylase increased with its average molecular weight. This ability increased regularly for PRPs up to 4500 Da, whereas the ability to bind the globular proteins decreased beyond 3400 Da. © 2001 Society of Chemical Industry     

Simultaneous HPLC quantification of total cholesterol,tocopherols and β-carotene in Barrosã-PDO veal

A simple, rapid and sensitive procedure for the simultaneous determination of total cholesterol, tocopherols and β-carotene in meat is described. The method involves a direct saponification of the meat, a single n-hexane extraction and the analysis of the extracted compounds by normal-phase HPLC, using fluorescence (tocopherols) and UV–Vis photodiode array (cholesterol and β-carotene) detections in tandem. Rates of recovery of spiked meat samples were 93% for cholesterol, 83–86% for (α-, β- and -γ) tocopherols and 89% for β-carotene. Repeatabilities were high (CV < 6%) for all determined compounds, except for δ-tocopherol. This tocopherol, which is not usually present in meat, showed a much lower recovery percentage (73%) and repeatability (12.8%). This methodology was applied for the quantification of total cholesterol, tocopherols and β-carotene in three muscles (longissimus thoracis, longissimus lumborum and semitendinosus) of the Portuguese traditional Barrosã-PDO veal, obtained from autochthonous calves fed extensively during summer (with the least abundant green pastures) and slaughtered in early autumn (October). Barrosã-PDO veal showed median contents of total cholesterol (0.50–0.56 mg/g) and, depending on the analysed muscle, moderate to high contents of α-tocopherol (3.3–3.9 μg/g) and β-carotene (0.07–0.09 μg/g), suggesting an high sensorial and hygienic quality.     

Linear mixture model applied to Amazonian vegetation classification

Many research projects require accurate delineation of different secondary succession (SS) stages over large regions/subregions of the Amazon basin. However, the complexity of vegetation stand structure, abundant vegetation species, and the smooth transition between different SS stages make vegetation classification difficult when using traditional approaches such as the maximum likelihood classifier (MLC). Most of the time, classification distinguishes only between forest/non-forest. It has been difficult to accurately distinguish stages of SS. In this paper, a linear mixture model (LMM) approach is applied to classify successional and mature forests using Thematic Mapper (TM) imagery in the Rondônia region of the Brazilian Amazon. Three endmembers (i.e., shade, soil, and green vegetation or GV) were identified based on the image itself and a constrained least-squares solution was used to unmix the image. This study indicates that the LMM approach is a promising method for distinguishing successional and mature forests in the Amazon basin using TM data. It improved vegetation classification accuracy over that of the MLC. Initial, intermediate, and advanced successional and mature forests were classified with overall accuracy of 78.2% using a threshold method on the ratio of shade to GV fractions, a 7.4% increase over the MLC. The GV and shade fractions are sensitive to the change of vegetation stand structures and better capture biophysical structure information.     

Fuzzy ontologies-based user profiles applied to enhance e-learning activities

Nowadays, the impact of technological developments on improving human activities is becoming more evident. In e-learning, this situation is no different. There are common to use systems that assist the daily activities of students and teachers. Typically, e-learning recommender systems are focused on students; however, teachers can also benefit from these type of tools. A recommender system can propose actions and resources that facilitate teaching activities like structuring learning strategies. In any case, a complete user’s representation is required. This paper shows how a fuzzy ontology can be used to represent user profiles into a recommender engine and enhances the user’s activities into e-learning environments. A fuzzy ontology is an extension of domain ontologies for solving the problems of uncertainty in sharing and reusing knowledge on the Semantic Web. The user profile is built from learning objects published by the user himself into a learning object repository. The initial experiment confirms that the automatically obtained fuzzy ontology is a good representation of the user’s preferences. The experiment results also indicate that the presented approach is useful and warrants further research in recommending and retrieval information.     

Intracellular Ca2+ Signaling in Protozoan Parasites: An Overview with a Focus on Mitochondria

Ca²⁺ signaling has been involved in controling critical cellular functions such as activation of proteases, cell death, and cell cycle control. The endoplasmatic reticulum plays a significant role in Ca²⁺ storage inside the cell, but mitochondria have long been recognized as a fundamental Ca²⁺ pool. Protozoan parasites such as Plasmodium falciparum, Toxoplasma gondii, and Trypanosoma cruzi display a Ca²⁺ signaling toolkit with similarities to higher eukaryotes, including the participation of mitochondria in Ca²⁺-dependent signaling events. This review summarizes the most recent knowledge in mitochondrial Ca²⁺ signaling in protozoan parasites, focusing on the mechanism involved in mitochondrial Ca²⁺ uptake by pathogenic protists.     

Influence of green creativity on organizations: A case study from the perspectives of leaders and subordinates

The sustainability framework has a strong influence on the policies, practices and procedures of companies. Green creativity plays a pivotal role in the development of initiatives and innovations for the environmental pillar of sustainability. Based on a survey applied to a Portuguese company with an accredited environmental management system (N = 146), the findings reveal that green creativity is influenced in different ways when analysed from distinct perspectives. The leader's green creativity is positively influenced by the subordinate's green self-efficacy and personal identification with the leader, whereas the subordinate's green creativity is positively influenced by their green passion and green self-efficacy, and the leaders' green creativity. This study shows that green creativity develops differentially according to distinct job positions and expectations that in practice must be complementary and synergistic for its effective development.     

Understanding dengue fever dynamics: a study of seasonality in vector-borne disease models

Dengue fever dynamics show seasonality, with the disease transmission being higher during the warmer seasons. In this paper, we analyse seasonally forced epidemic models with and without vector dynamics. We assume small seasonal effects and obtain approximations for the real response of each state variable and also for the corresponding amplitude and phase via decomposition of the sinusoidal forcing into imaginary exponential functions. The analysis begins with the simplest susceptible-infected-susceptible (SIS) model, followed by the simplest model with vector dynamics, susceptible-infected-susceptible for hosts and uninfected-vector (SISUV). Finally, we compare the more complex susceptible-infected-recovered (SIR) and susceptible-infected-recovered for hosts and uninfected-vector (SIRUV) models and conclude that the models give basically the same information when we replace, in the SIR model, the human infectivity by a function of both human and mosquito infectivities.     

Analyses and improvement of a broadcasting multiple blind signature scheme based on quantum GHZ entanglement

A broadcasting multiple blind signature scheme based on quantum GHZ entanglement has been presented recently. It is said that the scheme’s unconditional security is guaranteed by adopting quantum key preparation, quantum encryption algorithm and quantum entanglement. In this paper, we prove that each signatory can get the signed message just by an intercept–resend attack. Then, we show there still exist some participant attacks and external attacks. Specifically, we verify the message sender Alice can impersonate each signatory to sign the message at will, and so is the signature collector Charlie. Also, we demonstrate that the receiver Bob can forge the signature successfully, and with respect to the external attacks, the eavesdropper Eve can modify the signature at random. Besides, we discover Eve can change the signed message at random, and Eve can impersonate Alice as the message sender without being discovered. In particular, we propose an improved scheme based on the original one and show that it is secure against not only the attacks mentioned above but also some collusion attacks.     

Studies on SiC, DLC and TiO2 thin films as piezoresistive sensor materials for high temperature application

The use of thin films as sensing elements for microsensor applications has been shown very attractive due to their low-cost fabrication, potential for integration with standard CMOS technologies and possibility of deposition on different substrate types. In particular, piezoresistive sensors based on thin films have been commonly developed because can be easily implemented using microfabrication processes and present the best relation between sensitivity and system complexity, which showing great advantages in term of device integration. In our previous works (Fraga et al. 2010, 2011a), we studied undoped and nitrogen-doped PECVD a-SiC thin films as alternative materials to replace the silicon piezoresistors in strain and pressure sensors for harsh environments. Here, we focused our attention on the piezoresistive properties of sputtered silicon carbide (SiC), diamond-like carbon (DLC) and titanium dioxide (TiO₂) thin films. These materials were evaluated in terms of sensitivity or gauge factor and of the influence of the temperature on this sensitivity, allowing a preliminary analysis of the applicability of these thin films in high temperature piezoresistive sensors.