Optimal solution of a diffusion equation with a discrete source term

In this paper we study the numerical behavior of a diffusion equation with a discrete control source term. The equation is discretized in space by finite differences and in time by an implicit scheme. The control variables are calculated in order to minimize an objective function, taking into account some restrictions. We define two strategies to obtain the optimal solution and present some numerical results in a context of a model that describes the oxygen concentration in a single chamber microbial fuel cell

Aquaponics as a sustainable and healthy food production system for Portugal

The aquaponics biological cycle Aquaponics has enormous potential in the regulation and recycling of valuable nutrients, otherwise lost to the environment with pollution potential. Aquaponics integrates freshwater aquaculture and hydroponics in a mini ecosystem. It uses the water of a Recirculating Aquaculture System (RAS) in soilless plant farming. The process includes a biofilter where nitrifying bacteria oxidize ammonia, resulting from fish excreta or uneaten feed, into nitrates and nitrites. While fish are extremely sensitive to ammonia, they are more tolerant to nitrates and nitrites. Nevertheless, these need also to be removed from the fish environment before accumulation to toxic levels. This is where hydroponics may come in as a useful manner of disposing nitrogen off the RAS. Nitrogen is the main macronutrient for plant growth, therefore an indispensable element in fertilization. The advantages of combining a RAS with hydroponics becomes therefore evident as a win-win solution for the problematic nitrates of the RAS and the expensive nitrogen fertilizers of plant production.N/

European citizens’ evaluation of the Common Agricultural Policy

The Common Agricultural Policy (CAP) is crucial in ensuring food safety and security in Europe. Providing a stable and diverse food supply also supports rural economies and promotes social, environmental and economic sustainability. However, as CAP consumes approximately 30% of the EU budget, debates regarding its pertinence have arisen. This paper aimed to understand European citizens’ perceptions of CAP, its associated benefits and their level of agreement regarding the allocation of the EU budget. Ultimately, the goal was to gain insights into EU citizens’ attitudes and perceptions towards the CAP. Information and data come from the European Survey Eurobarometer. The methods include statistical inferential techniques adjusted to the nature of the variables and goals. The findings confirm that European citizens generally perceive the CAP positively and have positive attitudes about the CAP. While some differences among various social groups may exist, the results did not identify any specific group strongly opposing the CAP. Overall, European citizens hold a favorable attitude towards the CAP, its associated benefits and budget allocation. This paper brings new insights into new European CAP measures and programs to promote food security and the sustainability of agriculture among European countries and citizens. These insights may be useful for public decision-makers to define better policies and measures adjusted to European citizens and to promote food security and sustainability.info:eu-repo/semantics/publishedVersio

Consumption of honey in Portugal: consumers’ attitudes, perceptions and trends

Consumers’ attitudes about reveal important information about the production and supply chain of food and the commercialisation process (Unnevehr et al., 2010). To fully understand a consumption market, it is important to study the symbolic representations of consumption habits (Bekker et al., 2017). The consumer perceives consumption accordingly to social norms and values, and consumption habits cannot be analyzed as individual phenomena. Choices are under the influence of norms, values, taboos, permissions, prohibitions, and beliefs (Andorfer & Liebe, 2013). The consumers’ attitudes have been considered important determinants of their behaviour. The Ajzen’s Planned Behaviour Theory (APBT) (Ajzen, 1991) is based in the presumption that people behave in a sensible way, consider the information available, and consider the implications of their actions. The theory postulates that a person’s interest to perform or not a certain behaviour is a direct function of individually and socially related variables. The individual component is based in the individual attitude or mood to react favourably or unfavourably to an object, individual, institution, or event (Kim and Hunter, 1993). The social component includes the subjective norms determined by the perception of the social pressures acting on the individual, to perform or not a certain behaviour (Ajzen 1991N/

Profiling alumni of a Brazilian public dental school

<p>Abstract</p> <p>Background</p> <p>Follow-up studies of former students are an efficient way to organize the entire process of professional training and curriculum evaluation. The aim of this study was to identify professional profile subgroups based on job-related variables in a sample of former students of a Brazilian public dental school.</p> <p>Methods</p> <p>A web-based password-protected questionnaire was sent to 633 registered dentists who graduated from the Federal University of Goias between 1988 and 2007. Job-related information was retrieved from 14 closed questions, on subjects such as gender, occupational routine, training, profits, income status, and self-perception of professional career, generating an automatic database for analysis. The two-step cluster method was used for dividing dentists into groups on the basis of minimal within-group and maximal between-group variation, using job-related variables to represent attributes upon which the clustering was based.</p> <p>Results</p> <p>There were 322 respondents (50.9%), predominantly female (64.9%) and the mean age was 34 years (SD = 6.0). The automatic selection of an optimal number of clusters included 289 cases (89.8%) in 3 natural clusters. Clusters 1, 2 and 3 included 52.2%, 30.8% and 17.0% of the sample respectively. Interpretation of within-group rank of variable importance for cluster segmentation resulted in the following characterization of clusters: Cluster 1 - specialist dentists with higher profits and positive views of the profession; Cluster 2 - general dental practitioners in small cities; Cluster 3 - underpaid and less motivated dentists with negative views of the profession. Male dentists were predominant in cluster 1 and females in cluster 3. One-way Anova showed that age and time since graduation were significantly lower in Cluster 2 (<it>P </it>< 0.001). Alternative solutions with 4 and 5 clusters revealed specific discrimination of Cluster 1 by gender and dental education professionals.</p> <p>Conclusions</p> <p>Cluster analysis was a valuable method for identifying natural grouping with relatively homogeneous cases, providing potentially meaningful information for professional orientation in dentistry in a variety of professional situations and environments.</p

Effects of organic/inorganic amendments on trace elements dispersion by leachates from sulfide-containing tailings of São Domingos mine, Portugal. Time evaluation

Greenhouse pot experiments were conducted over 13 months to evaluate the effect of two amendment mixture doses (30 and 75 Mg/ha) on the geochemical dispersion of trace elements by leaching hazardous mine wastes from the São Domingos mine. Mineralogical evolution of these materials was also evaluated. Amendment mixtures containing solid wastes from agriculture (plant remains + strawberry substrate and rockwool used for the strawberry crop) and fromdistillation of Ceratonia siliqua L. and Arbutus unedo L. fruitswere used to improve the chemical characteristics of leachates fromsulfide minewastes. Sulfide mine wastes had acidic characteristics, aswell as high electrical conductivity and total element concentrations (g/kg; Al: 54.8–61.2; Fe: 104.0–110.0; Pb: 9.0–13.8; S: 63.6–68.0; As: ≈1). These features contributed to the large capacity for leaching of hazardous elements during, at least, the first fourmonths of incubation. In the seventh month of incubation, therewas a significant decrease in the leachate concentration of the majority of hazardous elements. The addition of amendments minimised trace element dispersion in leachate percolation during the first seven months (25 to 99% reduction compared to control, depending on the element and sampling period). However, the leachate characteristics were not influenced by amendment doses and no significant differences were observed in leachate composition (control and amended treatments) after 13 months. Amendment application led to differences between the solid phases of the efflorescent salts formed on the surface of the control and the amended treatments. The efflorescent salts contained very soluble aluminium sulfates, together with alunite–jarosite-group solid phases in amended samples, and copiapite-group solid phases in control. In the core materials (5 to 10 cmin depth), themineralogy was similar in both control and amended samples. The presence of various stable solid phases from alunite– jarosite-group, such as jarosite and beudantite (mainly in deeper materials), can explain the low concentrations of trace elements in the leachates after thirteen monthsinfo:eu-repo/semantics/publishedVersio

Dysregulation of H/ACA ribonucleoprotein components in chronic lymphocytic leukemia

Telomeres are protective repeats of TTAGGG sequences located at the end of human chromosomes. They are essential to maintain chromosomal integrity and genome stability. Telomerase is a ribonucleoprotein complex containing an internal RNA template (hTR) and a catalytic subunit (hTERT). The human hTR gene consists of three major domains; among them the H/ACA domain is essential for telomere biogenesis. H/ACA ribonucleoprotein (RNP) complex is composed of four evolutionary conserved proteins, including dyskerin (encoded by DKC1 gene), NOP10, NHP2 and GAR1. In this study, we have evaluated the expression profile of the H/ACA RNP complex genes: DKC1, NOP10, NHP2 and GAR1, as well as hTERT and hTR mRNA levels, in patients with chronic lymphocytic leukemia (CLL). Results were correlated with the number and type of genetic alteration detected by conventional cytogenetics and FISH (fluorescence in situ hybridization), IGHV (immunoglobulin heavy chain variable region) mutational status, telomere length (TL) and clinico pathological characteristics of patients. Our results showed significant decreased expression of GAR1, NOP10, DKC1 and hTR, as well as increased mRNA levels of hTERT in patients compared to controls (p=0.04). A positive correlation between the expression of GAR1-NHP2, GAR1-NOP10, and NOP10-NHP2 (p=0.0001), were observed. The analysis taking into account prognostic factors showed a significant increased expression of hTERT gene in unmutated-IGHV cases compared to mutated-CLL patients (p = 0.0185). The comparisons among FISH groups exhibited increased expression of DKC1 in cases with two or more alterations with respect to no abnormalities, trisomy 12 and del13q14, and of NHP2 and NOP10 compared to those with del13q14 (p = 0.03). The analysis according to TL showed a significant increased expression of hTERT (p = 0.0074) and DKC1 (p = 0.0036) in patients with short telomeres compared to those with long TL. No association between gene expression and clinical parameters was found. Our results suggest a role for these telomere associated genes in genomic instability and telomere dysfunction in CLL.Fil: Dos Santos, Patricia Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Panero, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Stanganelli, Carmen Graciela. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas "Mariano R. Castex"; ArgentinaFil: Palau Nagore, Maria Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Stella, Flavia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Bezares, Raimundo F.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Dr. Teodoro Álvarez"; ArgentinaFil: Slavutsky, Irma Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; Argentin