3,078 research outputs found
High precision navigation integrating satellite information - GPS - and inertial systema data
Dissertation submitted for obtain the degree of Doctor, at the Faculty of Engineering of the University of Port
Three-dimensional electrospun constructs for wound healing applications
This thesis embraces the opportunity to develop a wound dressing substrate that not only attends the functional requirements of a wound dressing, but also avoids the need of secondary dressings. Novel electrostatically driven self-assembled fibrous based materials made of poly(ε-caprolactone) are manufactured, resulting in asymmetrical materials with enhanced topographies.
Such constructs are characterized by a flat bottom side and a top side populated with
fibrous-based microsized protrusions, which have a median inter-protusion distance of 528 μm and a median peak density of 73 peaks per cm2. For the first time, it is provided a full explanation of the underlying fabrication phenomena, suggesting new routes to other polymers such as gelatin or chitosan. After the characterization of the proposed substrates, such materials are functionalized by layer-by-layer. Several combinations of polyelectrolytes (chitosan, gelatin, alginate, hyaluronic acid, poly-1, linear polyethyleneimine and dextran sulphate) and layer numbers (n = 1, 3, 5 or 10) are tested regarding the physicochemical properties of the generated multi-layered films, as well as the cellular adhesion on these constructs. It is intended to formulate, test and control, the underlying phenomena that avoids the cellular adhesion and proliferation within the used dressing. As prepared these materials are capable of withstanding (11.0 ± 0.3)×104 kg per m2 after 14 days of hydration. Their unique asymmetry promotes unidirectional liquid uptake (from the top side towards the inner structure of the materials), while being impermeable to potential external liquid-forms of infection at its bottom side. Nevertheless, such constructs also observed the high porosity (89.9%) and high surface area (1.44 m2.g-1) characteristic of traditional electrospun mats. The selected coating reduced cellular adhesion on the constructs throughout the generation of a rubbery film layer, which would also provide a means to tailor water vapor transmission and swelling ratio for different wound environments specifications (e.g. ischemic wounds, I/II/III-degree burns, etc.). As a showcase, functionalized wound dressing substrates were able to achieve 90 ± 0.5 % of wound closure within 48 hours
Innovation and Environmental Policy: Clean vs. Dirty Technical Change
We study a two sector endogenous growth model with environmental quality with two goods and two factors of production, one clean and one dirty. Technological change creates clean or dirty innovations. We compare the laissez-faire equilibrium and the social optimum and study first- and second-best policies. Optimal policy encourages research toward clean technologies. In a second-best world, we claim that a portfolio that includes a tax on the polluting good combined with optimal innovation subsidy policies is less costly than increasing the price of the polluting good alone. Moreover, a discriminating innovation subsidy policy is preferable to a non-discriminating one. JEL codes: H23, O3, O41Pollution, Endogenous Growth, Innovation, Environmental Policy, Laissez-Faire Equilibrium, Optimal Equilibrium, Discriminating vs. Non-Discriminating Subsidies to R&D
Technology Adoption in Nonrenewable Resource Management
Nonrenewable resource scarcity has been a traditional concern when designing optimal growth models. Technological change has played an important role in those models, since its presence is assumed to mitigate the depletion effect on extraction paths over time. We formalize the general problem of a competitive nonrenewable resource extracting firm to analyze optimal extraction behavior and technology adoption when adoption is costly, both in a deterministic and a stochastic environment, when the firm either anticipates adoption or not. Based on a quadratic extraction cost function, our results do not support the traditional view according to which the firm will only incur in an adoption cost when the stock is depleted enough.nonrenewable resources; technology adoption; depletion effect; cost of adoption.
The open pan-genome architecture and virulence landscape of Mycobacterium bovis
Animal tuberculosis (TB) is an emergent disease caused by Mycobacterium bovis, one of the animal-adapted ecotypes of the Mycobacterium tuberculosis complex (MTC). In this work, whole-genome comparative analyses of 70 M. bovis were performed to gain insights into the pan-genome architecture. The comparison across M. bovis predicted genome composition enabled clustering into the core- and accessory-genome components, with 2736 CDS for the former, while the accessory moiety included 3897 CDS, of which 2656 are restricted to one/two genomes only. These analyses predicted an open pan-genome architecture, with an average of 32 CDS added by each genome and show the diversification of discrete M. bovis subpopulations supported by both core- and accessory-genome components. The functional annotation of the pan-genome classified each CDS into one or several COG (Clusters of Orthologous Groups) categories, revealing ‘transcription’ (total average CDSs, n=258), ‘lipid metabolism and transport’ (n=242), ‘energy production and conversion’ (n=214) and ‘unknown function’ (n=876) as the most represented. The closer analysis of polymorphisms in virulence-related genes in a restrict group of M. bovis from a multi-host system enabled the identification of clade-monomorphic non-synonymous SNPs, illustrating clade-specific virulence landscapes and correlating with disease severity. This first comparative pan-genome study of a diverse collection of M. bovis encompassing all clonal complexes indicates a high percentage of accessory genes and denotes an open, dynamic non-conservative pan-genome structure, with high evolutionary potential, defying the canons of MTC biology. Furthermore, it shows that M. bovis can shape its virulence repertoire, either by acquisition and loss of genes or by SNP-based diversification, likely towards host immune evasion, adaptation and persistence.info:eu-repo/semantics/publishedVersio
Genome-wide estimation of recombination, mutation and positive selection enlightens diversification drivers of Mycobacterium bovis
Genome sequencing has reinvigorated the infectious disease research feld, shedding light on disease
epidemiology, pathogenesis, host–pathogen interactions and also evolutionary processes exerted
upon pathogens. Mycobacterium tuberculosis complex (MTBC), enclosing M. bovis as one of its
animal-adapted members causing tuberculosis (TB) in terrestrial mammals, is a paradigmatic model
of bacterial evolution. As other MTBC members, M. bovis is postulated as a strictly clonal, slowly
evolving pathogen, with apparently no signs of recombination or horizontal gene transfer. In this
work, we applied comparative genomics to a whole genome sequence (WGS) dataset composed by
70 M. bovis from diferent lineages (European and African) to gain insights into the evolutionary forces
that shape genetic diversifcation in M. bovis. Three distinct approaches were used to estimate signs
of recombination. Globally, a small number of recombinant events was identifed and confrmed by
two independent methods with solid support. Still, recombination reveals a weaker efect on M. bovis
diversity compared with mutation (overall r/m= 0.037). The diferential r/m average values obtained
across the clonal complexes of M. bovis in our dataset are consistent with the general notion that
the extent of recombination may vary widely among lineages assigned to the same taxonomical
species. Based on this work, recombination in M. bovis cannot be excluded and should thus be a
topic of further efort in future comparative genomics studies for which WGS of large datasets from
diferent epidemiological scenarios across the world is crucial. A smaller M. bovis dataset (n= 42) from
a multi-host TB endemic scenario was then subjected to additional analyses, with the identifcation
of more than 1,800 sites wherein at least one strain showed a single nucleotide polymorphism (SNP).
The majority (87.1%) was located in coding regions, with the global ratio of non-synonymous upon
synonymous alterations (dN/dS) exceeding 1.5, suggesting that positive selection is an important
evolutionary force exerted upon M. bovis. A higher percentage of SNPs was detected in genes enriched
into “lipid metabolism”, “cell wall and cell processes” and “intermediary metabolism and respiration”
functional categories, revealing their underlying importance in M. bovis biology and evolution. A closer
look on genes prone to horizontal gene transfer in the MTBC ancestor and included in the 3R (DNA
repair, replication and recombination) system revealed a global average negative value for Taijima’s
D neutrality test, suggesting that past selective sweeps and population expansion after a recent
bottleneck remain as major evolutionary drivers of the obligatory pathogen M. bovis in its struggle
with the host.info:eu-repo/semantics/publishedVersio
Diagnostic Criteria For Temporomandibular Disorders: Self-instruction Or Formal Training And Calibration?
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Background: To investigate the difference in diagnostic reliability between self-instructed examiners and examiners taught in a Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) course and if the reliability of self-instructed examiners improves after the course. Methods: Six examiners were divided into three groups: (1) formal two-day training and calibration course at a DC/TMD training center (Course group), (2) self-teaching through documents and movie (Self group) with three examiners on each and the Self group later participated in the course (Self + course group). Each group examined sixteen subjects, total of 48 volunteers (36 patients with TMD and 12 asymptomatic) and the reliabilities in relation to the diagnoses derived by a Reference Standard Examiner were compared by Cohen's Kappa coefficient. Results: The reliability was good to excellent in all three groups of examiners for all DC/TMD diagnoses, except for Myofascial pain with referral in the Self + course group. The course seemed to improve the reliability regarding Myalgia and Arthralgia at the same time as the examiners experienced the course to be valuable for self-perceived ability and confidence. Conclusions: This study shows that the diagnostic reliability of formal DC/TMD training and calibration and DC/TMD self-instruction are similar, except for subgroups of Myalgia. Thus, self-instruction seems to be possible to use to diagnose the most common TMDs in general dental practice. The course further improves the reliability regarding Myalgia and Arthralgia at the same time as the examiners experienced the course to be valuable for self-perceived ability and confidence.16Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES [10225/13-7
Optimization Of the Manufacturing Process for School Portfolios Through the Implementation of The Cellular Layout
One of the most common problems encountered in the manufacturing process is improper layout. About 30% of production time is wasted on transporting materials and products. The causes of this waste are problems in the disposition of stock and machines in production, that is, in the factory layout production of school desks became more efficient with the use of the cell layout. The result found was that with the implementation of the cell layout, there was an increase in the number of wallets produced and a reduction in the waste of materials. It is concluded that the. In this context, the production line based on the cellular layout has been an excellent ally, since the cells of this layout can improve the use of available space, without increasing costs due to major renovations or constructions. To prove such improvements, through the implementation of the cell layout, the PSL method (Systematic Layout Planning) was used, which follows steps such as data collection, analysis of necessary and available space, and factory limitations. With these stages of knowledge and analysis of the factory, it becomes possible to discard layouts that do not fit the characteristics of the company, whether related to financial resources, available space, and factory culture. Using the Chi-Square test for statistical analysis, it was possible to verify that the cell layout is an efficient optimization tool in the school desks production process, as it brought numerous benefits to the factory under studies, such as increased productivity, greater organization, and flexibility in the processes
Modulating intermolecular interactions and rheological properties in silk fibroin using ultrasound frequencies
info:eu-repo/semantics/draf
New Concepts Towards the Synthesis of Digital Circuits Through Genetic Algorithms
This paper analyses the performance of a Genetic Algorithm using
two new concepts, namely a static fitness function including a discontinuity measure
and a fractional-order dynamic fitness function, for the synthesis of combinational
logic circuits. In both cases, experiments reveal superior results in terms of speed
and convergence to achieve a solution
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