Electromagnetic interference from digital signal transmission onpower line carrier channels

A procedure is presented to evaluate the electromagnetic field generated by a digital transmission system on multiconductor power-line carrier channels. The vertical component of the electric field and the horizontal component of the magnetic field are defined by approximate formulaes of varying accuracy, depending on the frequency and the distance from phase conductors. Field sources are the currents traveling along the line, which are evaluated by means of an accurate simulation model of the transmission system and a rigorous wave propagation algorithm. Frequency spectra and lateral profiles of the field components are computed for single-phase and two-phase couplings on a horizontal power line. Digital channel capacity is shown to increase as the pulse repetition interval T decreases. However, if T increases, the harmonic content of the input signal code increases and, consequently, electromagnetic pollution rises for a given carrier channel. It is concluded that the EMI (electromagnetic interference) level is an important constraint which must be taken into account when choosing T and, more generally, in the design of the digital transmission system     

Determination of citrus jams genuineness by flavonoid analysis

An easy technique that enables the analysis of flavonoids from citrus jams is described. The flavonoids from commercial sour orange, sweet orange, mandarin, lemon, bitter lemon, grapefruit and lime jams were analysed by HPLC. Each citrus jam has a characteristic flavonoid pattern that can be used in genuineness determinations. Commercial jams produced with mixtures of orange, lemon and grapefruit can easily be characterized by HPLC. No differences between the flavonoid profiles of natural fruits and those of the corresponding jams were observed, showing that the manufacturing process does not affect the flavonoid profile and, therefore, that this profile can be used in genuineness studies.     

Interaction of proteins with the mRNA for ribosomal protein L1 in Xenopus: structural characterization of in vivo complexes and identification of proteins that bind in vitro to its 5'UTR

Xenopus r-protein mRNAs are known to be coordinately regulated at the translational level. To find out if RNA/protein interactions are involved in this control mechanism, we have characterized the particles containing the translationally repressed rp-mRNA and we have investigated the proteins that specifically bind to this type of mRNA. By sedimentation analysis and isopycnic centrifugation we have found that the repressed rp-mRNAs are assembled in slow sedimenting complexes where the RNA is prevalent over the protein mass (2.3 to 1). This composition is maintained also after in vitro reconstitution of the particle. We carried out also a detailed analysis of in vitro RNA/protein complex formation by focusing our attention on the 5'UTR, very similar in different rp-mRNAs and important in the translational regulation. We describe specific interactions of L1 mRNA with four proteins. The binding site of two of them, 57 kD and 47 kD, is in the typical pyrimidine sequence at the 5' end and is position dependent. Proteins of the same size interact also with the analogous region of r-protein S1 and L14 mRNA, not with unrelated RNAs. Binding of two other proteins, 31 kD and 24 kD, in the downstream region of the 5'UTR was also observed. The most evident 57 kD protein has been partially purified. Although the binding of these proteins to the r-protein mRNA 5'UTR is specific, their involvement in the translation regulation remains to be proved.     

Hierarchical linear models in psychiatry: A bibliometric study

Development of research methods requires a systematic review of their status. This study focuses on the use of Hierarchical Linear Modeling methods in psychiatric research. Evaluation includes 207 documents published until 2007, included and indexed in the ISI Web of Knowledge databases; analyses focuses on the 194 articles in the sample. Bibliometric methods are used to describe the publications patterns. Results indicate a growing interest in applying the models and an establishment of methods after 2000. Both Lotka’s and Bradford’s distributions are adjusted to the data.     

Effect of selected ions from lyotropic series on lipid oxidation rate

Organic or inorganic salts, commonly present in foods as natural components or ingredients, can affect the hydrophobic/hydrophilic interactions among food components. In particular, modifying the physicochemical equilibrium in the media, the ionic species forming salts could affect the kinetics of chemical reactions occurring in foods. The aim of the present research was to study the influence of different ionic species from lyotropic series on the kinetics of lipid oxidation. For this purpose, salts containing antichaotropic (carbonate and acetate), neutral (Na⁺, K⁺) and chaotropic ions (Cl⁻) were added to soybean oil. Results indicate that potassium carbonate and potassium acetate present a strong antioxidant capacity, whereas no effect was detected for NaCl and KCl. The salt antioxidant activity was prevalently attributed to the antichaotropic anionic species present in the media, which could interact with hydroperoxides by virtue of their ability to form hydrogen bonds. These results appear to be of considerable interest for controlling the development of rancidity in foods.     

Biodesulfurization of two Colombian coals with native microorganisms

A biodesulfurization process was carried out for two coals from the southwest of Colombia using a consortium of native microorganisms Acidithiobacillus ferrooxidans-like and Acidithiobacillus thiooxidans-like. Characterization techniques as X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM/EDX) and chemical analysis were used in order to establish the mineralogy of the process. The sulfur content in coals varies from 2.6% to 5.7%, and pyrite is the main sulphide present in the inorganic phase. Other minerals in the substrates include kaolinite, calcite, dolomite and quartz. An 85–95% reduction of pyritic sulfur and 31–51% of total sulfur in a period of 30 days were achieved, for a particle size of − 74 µm, 10% w/v pulp density and 30 °C.     

How do stressors lead to burnout? The mediating role of motivation.

We extend existing stressor-strain theoretical models by including intrinsic motivation as a mediator between well-established job stressors and burnout. Though the link between situational stressors and burnout is well established, little is known about mechanisms behind this relationship. With a sample of 284 self-employed individuals, we examined motivation as a mediator to explain why situational factors impact 3 dimensions of burnout: emotional exhaustion, cynicism, and inefficacy. Motivation is an explanatory mechanism that drives human behavior and thought, and thus may have an impact on important well-being outcomes. As expected, intrinsic motivation was a full mediator for the effect of perceived fit on the inefficacy dimension of burnout. Unexpectedly, neither perceived fit nor motivation was related to the other 2 dimensions of burnout, and role ambiguity had only a direct effect on the inefficacy dimension; it was also unrelated to exhaustion and cynicism. We discuss implications of these findings for researchers as well as for practitioners. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes perceived by traditional fishing communities after a major dam disaster in Brazil

ABSTRACT

The paper reports a study of the responses of fishing communities, Regência and Povoação, located at the mouth of the Doce River, to the collapse of the Fundão dam, owned by Samarco Mineração, in 2015. After the disaster, the fishermen’s social and cultural practices have undergone drastic changes. The arrival of tailings in the river has impaired their routines and income. The fishermen and their families indicate a sense of loss of identity and insecurity because of the uncertainty. They do not know if they will be able to resume fishing in these waters. This feeling contrasts with the results of a study conducted before the disaster.     

Excellence in Engineering Education: Views of Undergraduate Engineering Students

The purpose of this study was to understand the views and perceptions of engineering undergraduate students on engineering education. The method of content analysis was used to analyze the language used by engineering undergraduate students, and to extract the underlying common factors or perceived characteristics of “Excellence in Engineering Education.” These common factors were then used to identify and compare the similarities and differences in views between engineering students and perspectives from three types of stakeholders in the field. Forty‐seven undergraduate engineering students (17 females and 30 males) participated voluntarily in this study to answer four individual questions and ten group questions. The results showed that students strongly emphasized the importance of their own roles in the educational system and the value of instructional technology and real work examples in enhancing the quality of engineering education. The implications of the research results on excellence in engineering education are discussed.     

Effects of hydrogen on the mechanical properties of a 2 1/4Cr–1Mo steel

This paper explores the effects of hydrogen on the mechanical properties of a 2 1/4Cr–1Mo steel. The results for both microstructural conditions, as received and aged, indicated a loss of ductility after hydrogen charging treatment, but the yield strength and ultimate tensile strength remained unaltered. The fractograph analysis revealed that the fracture mode was modified by the hydrogen. The steel in the as-received condition showed craters and fisheyes on the fracture surface. The aged steel showed a brittle appearance associated with cleavage facets and small portion of areas with dimples. The hydrogen diffusivity and solubility were investigated using electrochemical permeation technique. It was observed that the hydrogen diffusivity decreased from 2.3 ± 0.4 × 10⁻¹⁰ m² s⁻¹ in the as-received condition to 5.7 ± 0.1 × 10⁻¹¹ m² s⁻¹ in the aged condition. The hydrogen solubility showed an increase for the aged condition in comparison to the as received sample. Both phenomena can be attributed to carbide evolution during aging, resulting in an increase of the carbide/matrix interfacial area.