Stellar Populations, Bars and Secular Evolution in Late-Type Galaxies

We have done a robust statistical analysis of UBV color profiles of 257 Sbc barred and unbarred galaxies. We found that there is an excess of barred galaxies among the objects with null or positive (bluish inward) color gradients, which seems to indicate that bars act as a mechanism of homogenization of the stellar population along galaxies. Moreover, the relationship found between total and bulge colors shows that, in the process of homogenization, the stellar population of bulges are getting bluer, whereas the total color of galaxies remains the same. These characteristics are expected in a secular evolutionary scenario, and seem incompatible with both the monolithic and the hierarchical scenarios for spiral galaxy formation.Comment: 2 pages, 1 table, no figures. To appear in ASP Conference Series, "Galaxy Disks and Disk Galaxies", J. G. Funes S. J. and E. M. Corsini, ed

Solving rank-constrained semidefinite programs in exact arithmetic

We consider the problem of minimizing a linear function over an affine section of the cone of positive semidefinite matrices, with the additional constraint that the feasible matrix has prescribed rank. When the rank constraint is active, this is a non-convex optimization problem, otherwise it is a semidefinite program. Both find numerous applications especially in systems control theory and combinatorial optimization, but even in more general contexts such as polynomial optimization or real algebra. While numerical algorithms exist for solving this problem, such as interior-point or Newton-like algorithms, in this paper we propose an approach based on symbolic computation. We design an exact algorithm for solving rank-constrained semidefinite programs, whose complexity is essentially quadratic on natural degree bounds associated to the given optimization problem: for subfamilies of the problem where the size of the feasible matrix is fixed, the complexity is polynomial in the number of variables. The algorithm works under assumptions on the input data: we prove that these assumptions are generically satisfied. We also implement it in Maple and discuss practical experiments.Comment: Published at ISSAC 2016. Extended version submitted to the Journal of Symbolic Computatio

Evaluation of wood basic density as an indirect measurement of the volume of wood raw material

The manufacturing process of wood agglomerate integrates distinct unit that transforms wood raw material into wood agglomerate. The yield of wood agglomerate produced is influenced by the density and the quality of the initial raw material. This work has compared two distinct methodologies aimed at defining the yield of the process through an indirect measurement at the precursor material. Samples (logs of differentiated sizes) were collected immediately at the industry entrance and several parameters were measured. The logs basic density and the moisture content was annotated, through analysis of the corresponding dry and wet mass. Log bark percentage has estimated also at the level of dry and wet basis. These parameters were used to determine the wood volume from different provenance and species in the beginning of the industrial process. The results indicated that wasn’t a great difference between the two different methods to determine the wood basic density and the wood volume in m3. Principal components analysis was used to investigate the differences between different provenances and different species for the wood basic density, and we conclude there is a great variability in wood basic density for the hardwood species than the observed for the softwood and there isn’t a great variability between different provenances. We study too the difference off wood moisture that could be occurring before the evaluation of wood basic density

Kinetics of laccase mediator system delignification of an Eucalyptus globulus Kraft pulp

Comunicação da qual só está disponível o resumo.Laccase mediator system (LMS) was applied to one industrial Eucalyptus globulus kraft pulp with kappa numbers 15.2, using violuric acid (VA) as mediator. The objective of the present work is to quantify the influence of the reaction conditions on the delignification rate and extent, establishing the kinetic equations. The effects of oxygen pressure, laccase and mediator charges, and reaction time on delignification were evaluated. The kinetic studies were carried out in a 1.5 L jacketed reactor with temperature control and magnetic mixer. The experiments were carried out with 10 grams of pulp at very low consistency (0.6%) in order to minimize inter-fibre mass transfer resistances. The oxygen pressure was varied between 1 and 7 bar and no significant differences were observed in terms of delignification rate and extent, at a given charge of laccase and mediator. The laccase (EC 1.10.3.2) charge was ranged between 10 and 250 IU per gram of pulp and the mediator between 10 and 70 mg per gram of pulp. The presence of mediator is required because the enzyme cannot diffuse into the porous structure of the fibre wall, where lignin should be oxidised. The delignification potential of the LMS was evaluated by measuring the kappa number of the pulp, after alkaline extraction. Control tests similar to the LMS followed by alkaline extraction, but without enzyme, were carried out and the mean value of kappa number was 14.04. The decrease of the kappa number of the pulp from 15.2 to 14.04 can be interpreted as the consequence of the extraction of some fragments of lignin during the two stages. This procedure enable us to access the real effect of laccase. The hexeneuronic acid (HexA) has, particularly in hardwood pulps, an important contribution to the kappa number value. However, the experimental data have shown that LMS does not remove significantly the HexA, which is in good agreement with the literature. So, the kappa number can be used to evaluate the potential of LMS to lignin extraction. For the levels of laccase 50 IU per gram and 40 mg of VA per gram, the delignification was reached 37%, which is a good result. The profile of kappa number with reaction time follows an exponential trend. In addition, the initial rate methodology is being used to quantify the influence of laccase and mediator concentrations on the kinetic rate. The data have shown that the delignification rate exhibits a linear dependence on the mediator concentration, for the low range tested. The effect of laccase charge seems to be lower. The experimental data are under exploitation

The impact of Instagram influencer marketing in the restaurant industry

When improving their offer, restaurants should also communicate adequately and draw the attention of the public, taking advantage of all available means of communication and opting for the most effective marketing techniques. Therefore, the main objective is to study the six dimensions that encompass a set of digital influencers’ characteristics and to understand if this is actually a communication channel that positively impacts the Portuguese restaurant sector. Using a mixed-method approach, we combined a qualitative study based on a focus group with a survey for a quantitative study. Findings reveal that of the six dimensions of the research model, only one has no impact on the increase of potential clients. In this way, the remaining five are considered to be sufficiently differentiating to arouse consumer interest in visiting restaurants promoted by Instagram influencers.info:eu-repo/semantics/publishedVersio

Envelhecimento acelerado de aguardentes vínicas na presença de fragmentos de madeira. Influência nos compostos odorantes

A tecnologia de envelhecimento tradicional, que consiste na colocação da aguardente vínica em vasilhas de madeira durante vários anos, é uma técnica morosa e onerosa. Assim, têm vindo a ser introduzidas e desenvolvidas novas técnicas, com o intuito de optimizar o processo e reduzir os custos. Uma dessas novas técnicas consiste em introduzir pedaços de madeira (aparas, toros ou outras formas) na bebida a envelhecer, condicionada em depósitos de inox. Têm sido realizados muitos estudos em vinhos, mas em aguardentes a experimentação é escassa [1, 2]. Assim, este trabalho teve como objectivo avaliar a influência da utilização de alternativas ao envelhecimento de aguardentes em vasilhas de madeira, na composição química das aguardentes obtidas, dando particular atenção aos compostos odorantes provenientes da madeira. Para tal, uma mesma aguardente vínica da Lourinhã foi submetida a um processo de envelhecimento, com três formas de madeira: aguardente colocada em vasilha de madeira (V), aguardente colocada em vasilha de inox com introdução de madeira sob a forma de dominós (D) e aguardente colocada em vasilha de inox com introdução de madeira sob a forma de tábuas (T), tendo sido colhidas amostras de aguardente, ao fim de 180 dias de envelhecimento, para análise e quantificação dos compostos odorantes. Os resultados obtidos mostram que a forma da madeira teve um efeito altamente significativo na maioria dos compostos analisados. No caso dos compostos odorantes derivados da lenhina da madeira (fenois voláteis e vanilina), os teores mais elevados foram encontrados nas aguardentes envelhecidas na presença de fragmentos (dominós ou tábuas), enquanto para os compostos odorantes derivados das hemiceluloses da madeira (ácido acético e aldeídos furânicos) os teores mais elevados foram determinados nas aguardentes envelhecidas em vasilha de madeira. Os resultados deste trabalho sugerem a possibilidade de diferenciação química das aguardentes, em função da tecnologia de envelhecimento

Avaliação do potencial fertilizante de dois resíduos da indústria florestal

A indústria florestal produz resíduos com características e potenciais de utilização muito distintos. Por um lado, a queima de biomassa florestal para obtenção de energia conduz à produção de grandes quantidades de cinzas como produto final e, por outro lado, durante o processo de produção da pasta de papel e na sequência do tratamento por causticação é também produzido um resíduo em quantidades significativas. O objectivo deste trabalho foi avaliar o potencial fertilizante destes dois resíduos, ou seja, das cinzas provenientes da incineração de biomassa florestal e das cinzas provenientes da causticação da pasta de papel, resíduos provenientes da indústria florestal. Num ensaio em vasos estudou-se a resposta do azevém à aplicação de doses crescentes destes resíduos que corresponderiam à aplicação ao solo de 0, 0,5, 1, 3 e 5 toneladas por ha. Verificou-se que a cinza de biomassa florestal pode ser aplicada ao solo, não se observando efeitos negativos na produção ou propriedades do solo. Esta aplicação conduzirá ao fornecimento de alguns nutrientes, nomeadamente K e Ca. Em solos com relação Ca/Mg elevada aconselha-se a aplicação simultânea de Mg. O resíduo proveniente da causticação da pasta de papel, deve ser incorporado no solo com antecedência relativamente à sementeira devido à sua causticidade. Nas culturas plurianuais não deverá ser utilizado. Apresentou valor como correctivo alcalinizante, possuindo elevado teor em Na que conduziu a um aumento significativo da condutividade eléctrica e do Na de troca, não se aconselhando uma aplicação em quantidades superiores a 1 t/ha

Influence of the kind of wood (chestnut and Limousin oak) in the extractives and Klason lignin contents of wood fragments used in the ageing of wine brandies

Só está disponível o resumo da comunicação.Influence of the kind of wood (chestnut and Limousin oak) in the extractives and Klason lignin contents of wood fragments used in the ageing of wine brandie

Heavy Quark Symmetry Violation in Semileptonic Decays of D Mesons

The decays of $D$ mesons to $K l \nu$ and $K^* l \nu$ final states exhibit significant deviations from the predictions of heavy-quark symmetry, as one might expect since the strange quark's mass is of the same order as the QCD scale. Nonetheless, in order to understand where the most significant effects might lie for heavier systems (such as $B \to D l\nu$ and $B \to D^* l\nu$), the pattern of these deviations is analyzed from the standpoint of perturbative QCD and ${\cal O}(1/m_s)$ corrections. Two main effects are noted. First, the perturbative QCD corrections lead to an overall decrease of predicted rates, which can be understood in terms of production of excited kaonic states. Second, ${\cal O}(1/m_s)$ effects tend to cancel the perturbative QCD corrections in the case of $Kl\nu$ decay, while they have minimal effect in $K^*l\nu$ decay.Comment: 25 pages (LaTeX) + 7 pages of Postscript figures (included at end), EFI-92-3