Burnout and engagement in portuguese male military officers

Occupational stress is a contemporary concern due to its negative consequences in workers, especially when chronic, since it can provoke burnout (Freudenberger, 1974; Maslach, 1976). However, engagement is being identified as a possible protector of burnout and occupational stress (Schaufeli et al., 2002). Military officers have a dangerous and stressful activity, factor that is enhancing studies on burnout and engagement in this group (Alarcon et al., 2010; Chambel & Cruz, 2010; Ivie & Garland, 2011).info:eu-repo/semantics/publishedVersio

Development of hemostatic materials made of electrochemically oxidized bacterial cellulose

Book of Abstracts of CEB Annual Meeting 2017[Excerpt] Cellulose is the most abundant polysaccharide in nature, being the main constituent of plant cell walls. It can undergo structural modification by oxidative methods, making it absorbable when implanted in the organism, contrarily to what happens with the non-oxidized cellulose. This way it can be used as raw material in medical devices, such as absorbable hemostatic materials and as a barrier to prevent postoperative adhesions. Cellulose can also be produced by bacteria (mainly from the species Glucanocetobacter xylinus), being this way known as bacterial cellulose (BC). With the increasing use of the hemostatic materials based on oxidized cellulose in surgical procedures, there has also been an increase in the number of case studies that describe post-operative complications associated with the use of these materials. BC has improved characteristics and unique properties compared with polysaccharide derived from plants, namely a higher biocompatibility. It has therefore been the subject of increased research over the past years allowing its application in various fields, especially in biomedical applications [1]. This project aims to develop a hemostatic material to reduce post-operative complications, based on the oxidized BC, using electrochemical oxidation methods [2]. These methods are based on the stable nitroxyl radicals commercially available. [...]info:eu-repo/semantics/publishedVersio

On a generalised model for time-dependent variance with long-term memory

The ARCH process (R. F. Engle, 1982) constitutes a paradigmatic generator of stochastic time series with time-dependent variance like it appears on a wide broad of systems besides economics in which ARCH was born. Although the ARCH process captures the so-called "volatility clustering" and the asymptotic power-law probability density distribution of the random variable, it is not capable to reproduce further statistical properties of many of these time series such as: the strong persistence of the instantaneous variance characterised by large values of the Hurst exponent (H > 0.8), and asymptotic power-law decay of the absolute values self-correlation function. By means of considering an effective return obtained from a correlation of past returns that has a q-exponential form we are able to fix the limitations of the original model. Moreover, this improvement can be obtained through the correct choice of a sole additional parameter, $q_{m}$. The assessment of its validity and usefulness is made by mimicking daily fluctuations of SP500 financial index.Comment: 6 pages, 4 figure

Quantificação das estruturas de fluxo sin-magmáticas do Plutão de Vila Pouca de Aguiar: uma ferramenta para a quantificação estrutural e da qualidade da rocha

Mineral distribution pattern of Variscan post-tectonic granites from Vila Pouca de Aguiar Pluton (NE Portugal) were analyzed with methods partially based on fractal geometry and, with respect to rock inhomogeneity and anisotropy. The result of the analysis provides information about magmatic flux and mineral equilibrium processes in a crystallizing magma chamber. In addition, the used methods may also provide important information for the ornamental rock industry, because they allow fast and automatic evaluation of economic rock parameters.Os padrões de distribuição mineral dos granitos póstectónicos do plutão de Vila Pouca de Aguiar foram analisados com métodos parcialmente baseados na geometria fractal, atendendo à homogeneidade e anisotropia da rocha. O resultado desta análise forneceu informação acerca do fluxo magmático e dos processos de equilíbrio mineral na cristalização no interior de uma câmara magmática. Adicionalmente, os métodos utilizados ainda disponibilizaram informação importante para a indústria de pedra ornamental, pois permitem uma avaliação rápida e automática dos parâmetros que valorizam economicamente a rocha.(undefined

On exact time-averages of a massive Poisson particle

In this work we study, under the Stratonovich definition, the problem of the damped oscillatory massive particle subject to a heterogeneous Poisson noise characterised by a rate of events, \lambda (t), and a magnitude, \Phi, following an exponential distribution. We tackle the problem by performing exact time-averages over the noise in a similar way to previous works analysing the problem of the Brownian particle. From this procedure we obtain the long-term equilibrium distributions of position and velocity as well as analytical asymptotic expressions for the injection and dissipation of energy terms. Considerations on the emergence of stochastic resonance in this type of system are also set forth.Comment: 21 pages, 5 figures. To be published in Journal of Statistical Mechanics: Theory and Experimen

Analysis of return distributions in the coherent noise model

The return distributions of the coherent noise model are studied for the system size independent case. It is shown that, in this case, these distributions are in the shape of q-Gaussians, which are the standard distributions obtained in nonextensive statistical mechanics. Moreover, an exact relation connecting the exponent $\tau$ of avalanche size distribution and the q value of appropriate q-Gaussian has been obtained as q=(tau+2)/tau. Making use of this relation one can easily determine the q parameter values of the appropriate q-Gaussians a priori from one of the well-known exponents of the system. Since the coherent noise model has the advantage of producing different tau values by varying a model parameter \sigma, clear numerical evidences on the validity of the proposed relation have been achieved for different cases. Finally, the effect of the system size has also been analysed and an analytical expression has been proposed, which is corroborated by the numerical results.Comment: 14 pages, 3 fig

Synthesis and characterization of oxidized bacterial cellulose through electrochemical methods: its biodegradability and potential as hemostatic material

Bacterial cellulose (BC) is a biocompatible material with high purity, high crystallinity, high degree of polymerization and high-water content [1,2]. It could be applied in several fields, being the biomedical field the most relevant to this work where biodegradability is a key requirement. BC may be chemically modified through its hydroxyl groups, e.g., by oxidation, becoming reabsorbable and acquiring new features, such as hemostatic behaviour. Oxidation of BC membranes was achieved through electrolysis using tetramethylpiperidine-1-oxyl (TEMPO) radical. TEMPO is able to perform selective oxidation of the primary hydroxyl groups, meaning that only C6 is oxidized into carboxyl groups [3]. BC membranes were characterized by FT-IR, SEM, XRD and 13C-NMR. The degree of oxidation was evaluated by titration of the carboxyl groups and the hemostatic behaviour was investigated through whole blood coagulation tests. Both in vitro and in vivo biodegradability of oxidized membranes was evaluated. In vitro biodegradability was assessed in ultra-pure water after 3, 7, 14 and 63 days of incubation while in vivo biodegradability was studied in a rat model, for 3, 14 and 56 days. FT-IR spectra showed an increase on the absorption band around 1628 cm-1 attributed to the carboxylic acid vibration, as compared to non-oxidized membranes, revealing the formation of carboxylic acid groups [4]. SEM images revealed that the morphology of the membranes was not changed by the oxidation [5]. XRD patterns for all the oxidized samples were very similar to non-oxidized ones, suggesting that the crystal structure was preserved [6]. 13C-RMN results showed that the signal around 62 ppm corresponding to superficial C6 primary hydroxyl group decreased after the oxidation, while the peak around 174.6 ppm assigned to carboxylate groups appeared after oxidation, confirming the selective oxidation of C6 [7]. In vitro results showed that almost no degradation occurred on non-oxidized membranes demonstrating the relevance of the oxidation on the improvement on BC biodegradability. The hemostatic behaviour of the membranes evaluated through the whole blood clotting times assay demonstrated that, contrarily to non-oxidized membranes, the oxidized ones exhibited hemostatic activity [8]. In vivo biodegradability and biocompatibility of oxidized membranes was evaluated. Membranes were implanted subcutaneously and the inflammatory response was studied. The obtained results showed that there were no microscopic evidences of inflammation and even after 56 days of implantation, the oxidized membranes did not degrade completely. Nevertheless, oxidized membranes revealed good biocompatibility [9].info:eu-repo/semantics/publishedVersio

Components of multifractality in the Central England Temperature anomaly series

We study the multifractal nature of the Central England Temperature (CET) anomaly, a time series that spans more than 200 years. The series is analyzed as a complete data set and considering a sliding window of 11 years. In both cases, we quantify the broadness of the multifractal spectrum as well as its components defined by the deviations from the Gaussian distribution and the influence of the dependence between measurements. The results show that the chief contribution to the multifractal structure comes from the dynamical dependencies, mainly the weak ones, followed by a residual contribution of the deviations from Gaussianity. However, using the sliding window, we verify that the spikes in the non-Gaussian contribution occur at very close dates associated with climate changes determined in previous works by component analysis methods. Moreover, the strong non-Gaussian contribution found in the multifractal measures from the 1960s onwards is in agreement with global results very recently proposed in the literature.Comment: 21 pages, 10 figure

Development of a tomato spotted wilt virus (TSWV) risk evaluation methology for a processing tomato region

A risk map for the Tomato spotted wilt virus (TSWV) was elaborated for the main Portuguese processing tomato producing region, the “Ribatejo e Península de Setúbal” region, where periodically this virus causes severe losses. Forty nine tomato fields were monitored. Risk factors for TSWV infection were identified and quantified according to their relative importance in TSWV incidence. The risk factors considered for each field were: (1) presence of TSWV in tomato plants; (2) presence of TSWV in weeds which are hosts of TSWV vectors; (3) presence of TSWV vector thrips; (4) presence of TSWV host crops previously (in the two years before), namely, tomato, potato and sweet pepper; and (5) presence of greenhouses, urban areas or TSWV host crops next to the field (up to about 100m from its borders). A risk estimator was calculated for each field. Among the thrips (Thysanoptera) identified, belonging to 11 genera, four vector thrips species were detected: Frankliniella occidentalis (Pergande) and Thrips tabaci Lindman, the two most abundant ones, and F. intonsa (Trybom) and F. schultzei (Trybom). Blue sticky traps placed up to about 75 cm above the crop canopy caught F. occidentalis and T. tabaci more efficiently than the beating technique. The weeds Datura stramonium L., Arctotheca calendula (L.), and Conyza bonariensis (L.) were identified as TSWV winter repositories. This study proposes a methodology to be used by field technicians for the annual evaluation of TSWV risk at a regional level, for an improved planning of processing tomato crop in the following season