976 resultados para empirical methods


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Mestrado em Engenharia Geotécnica e Geoambiente

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica

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Mestrado em Contabilidade

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Saccharomyces cerevisiae as well as other microorganisms are frequently used in industry with the purpose of obtain different kind of products that can be applied in several areas (research investigation, pharmaceutical compounds, etc.). In order to obtain high yields for the desired product, it is necessary to make an adequate medium supplementation during the growth of the microorganisms. The higher yields are typically reached by using complex media, however the exact formulation of these media is not known. Moreover, it is difficult to control the exact composition of complex media, leading to batch-to-batch variations. So, to overcome this problem, some industries choose to use defined media, with a defined and known chemical composition. However these kind of media, many times, do not reach the same high yields that are obtained by using complex media. In order to obtain similar yield with defined media the addition of many different compounds has to be tested experimentally. Therefore, the industries use a set of empirical methods with which it is tried to formulate defined media that can reach the same high yields as complex media. In this thesis, a defined medium for Saccharomyces cerevisiae was developed using a rational design approach. In this approach a given metabolic network of Saccharomyces cerevisiae is divided into a several unique and not further decomposable sub networks of metabolic reactions that work coherently in steady state, so called elementary flux modes. The EFMtool algorithm was used in order to calculate the EFM’s for two Saccharomyces cerevisiae metabolic networks (amino acids supplemented metabolic network; amino acids non-supplemented metabolic network). For the supplemented metabolic network 1352172 EFM’s were calculated and then divided into: 1306854 EFM’s producing biomass, and 18582 EFM’s exclusively producing CO2 (cellular respiration). For the non-supplemented network 635 EFM’s were calculated and then divided into: 215 EFM’s producing biomass; 420 EFM’s producing exclusively CO2. The EFM’s of each group were normalized by the respective glucose consumption value. After that, the EFMs’ of the supplemented network were grouped again into: 30 clusters for the 1306854 EFMs producing biomass and, 20 clusters for the 18582 EFM’s producing CO2. For the non-supplemented metabolic network the respective EFM’s of each metabolic function were grouped into 10 clusters. After the clustering step, the concentrations of the other medium compounds were calculated by considering a reasonable glucose amount and by accounting for the proportionality between the compounds concentrations and the glucose ratios. The approach adopted/developed in this thesis may allow a faster and more economical way for media development.

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INTRODUCTION: Leprosy in Brazil is a public health issue, and there are many regions in the State of Espírito Santo with high endemic incidence levels of leprosy, characterizing this state as a priority for leprosy programs. The aim of this study was to determine the spatial distribution of coefficients of new cases of leprosy in the State of Espírito Santo, Brazil. METHODS: We conducted a descriptive and ecologic study based on the spatial distribution of leprosy in the State of Espírito Santo between 2004 and 2009. Data were gathered from the available records of the Espírito Santo State Health Secretary. The global and local Bayesian empirical methods were used to produce an estimate of leprosy risk, smoothing the fluctuation effects of the detection coefficients. RESULTS: The study resulted in a coefficient adjustment of new cases in 10 towns that changed their classification, among which, 2 went from low to medium, 4 from medium to high, 3 from high to very high, and 1 from very high to hyper-endemic. An average variation of 1.02, fluctuating between 0 and 12.39 cases/100,000 inhabitants, was found in a comparative calculation between the Local Ebest value and the average coefficient of new leprosy cases in the State of Espírito Santo. CONCLUSIONS: The spatial analysis of leprosy favors the establishment of control strategies with a better cost-benefit relationship since it reveals specific and priority regions, thereby enabling the development of actions that can interfere in the transmission chain.

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Background: Despite the increasing incidences of the publication of assessment frameworks intending to establish the "standards" of the quality of qualitative research, the research conducted using such empirical methods are still facing difficulties in being published or recognised by funding agencies. Methods: We conducted a thematic content analysis of eight frameworks from psychology/psychiatry and general medicine. The frameworks and their criteria are then compared against each other. Findings: The results illustrated the difficulties in reaching consensus on the definition of quality criteria. This showed the differences between the frameworks from the point of views of the underlying epistemology and the criteria suggested. Discussion: The aforementioned differences reflect the diversity of paradigms implicitly referred to by the authors of the frameworks, although rarely explicitly mentioned in text. We conclude that the increase in qualitative research and publications has failed to overcome the difficulties in establishing shared criteria and the great heterogeneity of concepts raises methodological and epistemological problems.

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The n-octanol/water partition coefficient (log Po/w) is a key physicochemical parameter for drug discovery, design, and development. Here, we present a physics-based approach that shows a strong linear correlation between the computed solvation free energy in implicit solvents and the experimental log Po/w on a cleansed data set of more than 17,500 molecules. After internal validation by five-fold cross-validation and data randomization, the predictive power of the most interesting multiple linear model, based on two GB/SA parameters solely, was tested on two different external sets of molecules. On the Martel druglike test set, the predictive power of the best model (N = 706, r = 0.64, MAE = 1.18, and RMSE = 1.40) is similar to six well-established empirical methods. On the 17-drug test set, our model outperformed all compared empirical methodologies (N = 17, r = 0.94, MAE = 0.38, and RMSE = 0.52). The physical basis of our original GB/SA approach together with its predictive capacity, computational efficiency (1 to 2 s per molecule), and tridimensional molecular graphics capability lay the foundations for a promising predictor, the implicit log P method (iLOGP), to complement the portfolio of drug design tools developed and provided by the SIB Swiss Institute of Bioinformatics.

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Object The goal of this study was to establish whether clear patterns of initial pain freedom could be identified when treating patients with classic trigeminal neuralgia (TN) by using Gamma Knife surgery (GKS). The authors compared hypesthesia and pain recurrence rates to see if statistically significant differences could be found. Methods Between July 1992 and November 2010, 737 patients presenting with TN underwent GKS and prospective evaluation at Timone University Hospital in Marseille, France. In this study the authors analyzed the cases of 497 of these patients, who participated in follow-up longer than 1 year, did not have megadolichobasilar artery- or multiple sclerosis-related TN, and underwent GKS only once; in other words, the focus was on cases of classic TN with a single radiosurgical treatment. Radiosurgery was performed with a Leksell Gamma Knife (model B, C, or Perfexion) using both MR and CT imaging targeting. A single 4-mm isocenter was positioned in the cisternal portion of the trigeminal nerve at a median distance of 7.8 mm (range 4.5-14 mm) anterior to the emergence of the nerve. A median maximum dose of 85 Gy (range 70-90 Gy) was delivered. Using empirical methods and assisted by a chart with clear cut-off periods of pain free distribution, the authors were able to divide patients who experienced freedom from pain into 3 separate groups: patients who became pain free within the first 48 hours post-GKS; those who became pain free between 48 hours and 30 days post-GKS; and those who became pain free more than 30 days after GKS. Results The median age in the 497 patients was 68.3 years (range 28.1-93.2 years). The median follow-up period was 43.75 months (range 12-174.41 months). Four hundred fifty-four patients (91.34%) were initially pain free within a median time of 10 days (range 1-459 days) after GKS. One hundred sixty-nine patients (37.2%) became pain free within the first 48 hours (Group PF(≤ 48 hours)), 194 patients (42.8%) between posttreatment Day 3 and Day 30 (Group PF((>48 hours, ≤ 30 days))), and 91 patients (20%) after 30 days post-GKS (Group PF(>30 days)). Differences in postoperative hypesthesia were found: in Group PF(≤ 48 hours) 18 patients (13.7%) developed postoperative hypesthesia, compared with 30 patients (19%) in Group PF((>48 hours, ≤ 30 days)) and 22 patients (30.6%) in Group PF(>30 days) (p = 0.014). One hundred fifty-seven patients (34.4%) who initially became free from pain experienced a recurrence of pain with a median delay of 24 months (range 0.62-150.06 months). There were no statistically significant differences between the patient groups with respect to pain recurrence: 66 patients (39%) in Group PF(≤ 48 hours) experienced pain recurrence, compared with 71 patients (36.6%) in Group PF((>48 hours, ≤ 30 days)) and 27 patients (29.7%) in Group PF(>30 days) (p = 0.515). Conclusions A substantial number of patients (169 cases, 37.2%) became pain free within the first 48 hours. The rate of hypesthesia was higher in patients who became pain free more than 30 days after GKS, with a statistically significant difference between patient groups (p = 0.014).

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A series of seven Schiff bases have been synthesized from 3,3-diphenylpropilamine and substituted benzaldehydes. These imines were treated with NaBH4 in ethanol affording the corresponding amines in 98-55% yields. A molecular modeling study was performed with the Schiff bases in order to compare the theoretical parameters with the experimental results. The theoretical parameters were obtained by AM1 and PM3 semi-empirical methods. The analysis of charge, electron densities and LUMO coefficients suggested that the most favorable interactions should occur with Schiff bases containing electron-donating groups, in accordance with experimental yields, showing that the higher reactivity is due to higher electrophilic character of imine carbons.

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The recent emergence of a new generation of mobile application marketplaces has changed the business in the mobile ecosystems. The marketplaces have gathered over a million applications by hundreds of thousands of application developers and publishers. Thus, software ecosystems—consisting of developers, consumers and the orchestrator—have emerged as a part of the mobile ecosystem. This dissertation addresses the new challenges faced by mobile application developers in the new ecosystems through empirical methods. By using the theories of two-sided markets and business ecosystems as the basis, the thesis assesses monetization and value creation in the market as well as the impact of electronic Word-of-Mouth (eWOM) and developer multihoming— i. e. contributing for more than one platform—in the ecosystems. The data for the study was collected with web crawling from the three biggest marketplaces: Apple App Store, Google Play and Windows Phone Store. The dissertation consists of six individual articles. The results of the studies show a gap in monetization among the studied applications, while a majority of applications are produced by small or micro-enterprises. The study finds only weak support for the impact of eWOM on the sales of an application in the studied ecosystem. Finally, the study reveals a clear difference in the multi-homing rates between the top application developers and the rest. This has, as discussed in the thesis, an impact on the future market analyses—it seems that the smart device market can sustain several parallel application marketplaces.

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Pienille ja keskisuurille yrityksille eli pk-yrityksille on olemassa useita kasvustrategioita. Nämä kasvustrategiat tähtäävät joko liiketoiminnan laajentamiseen, nykyisten resurssien hyödyntämiseen, uusien resurssien luotaamiseen tai liiketoiminnan supistamiseen. Valitsemaansa kasvustrategiaa noudattamalla yritys pyrkii pääsemään kasvutavoitteisiinsa. Tämän tutkimuksen tavoitteena on tieteellisen kirjallisuuden pohjalta arvioida kasvustrategioita ja valita niistä pienelle it-alalla toimivalle case-yritykselle sopivin. Sopivimmaksi havaitun kasvustrategian pohjalta case-yritykselle laaditaan räätälöity kasvustrategia. Kasvustrategian laatimiseen käytetään tieteellisen kirjallisuuden lisäksi empiirisenä menetelmänä tapaustutkimusta. Tapaustutkimus tehdään teemahaastatteluina kymmenelle yritykselle, joilla on liike-elämästä saatuja kokemuksia case-yritykselle valitusta kasvustrategiasta. Tutkimuksen tuloksena case-yritykselle sopivin kasvustrategia on verkostokasvustrategia. Verkostokasvustrategiaa noudattamalla case-yritys keskittyy omaan ydinosaamiseensa ja sen kehittämiseen ja hankkii tarvitsemansa muun osaamisen verkostokumppaneilta. Verkostoitumisen hyötyinä case-yritykselle on muun muassa pieni omien työntekijöiden tarve, tietotaidon saaminen, kilpailukyvyn paraneminen, markkinoinnin tehostuminen ja uusille markkinoille pääsyn helpottuminen. Verkostoitumisen haasteina case-yritykselle on sen sijaan muun muassa pienen yrityksen uskottavuusongelma, sopivien verkostokumppaneiden löytäminen ja epäluotettavat verkostokumppanit. Tutkimuksen johtopäätöksenä verkostoitumisesta saatavien hyötyjen nähdään kuitenkin olevan riskejä suuremmat case-yritykselle.

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Este documento describe el desarrollo de la educación técnica en Inglaterra, Alemania y Francia durante el siglo XIX, contrastando sus similaridades y diferencias. También analiza el papel del Estado en la provisión de educación técnica en estos países. El artículo sugiere que el alto estándar científico y técnico en la enseñanza, contribuyó significativamente para que el país se convirtiera en una potencia económica. Por ejemplo, la creciente superioridad técnica de los alemanes sobre los británicos en actividades como producción química, tinturas, hierro y acero, ha sido atribuida al hecho de que los británicos persistieron en el uso de métodos empíricos que representaban una barrera para alcanzar mejoras y adaptación, mientras que los alemanes desarrollaron un sistema de educación universitario y politécnico con fuertes lazos industriales que le permitían convertirse en la potencia industrial mas grande de Europa al inicio del Siglo XX.

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Soil organic carbon (SOC) plays a vital role in ecosystem function, determining soil fertility, water holding capacity and susceptibility to land degradation. In addition, SOC is related to atmospheric CO, levels with soils having the potential for C release or sequestration, depending on land use, land management and climate. The United Nations Convention on Climate Change and its Kyoto Protocol, and other United Nations Conventions to Combat Desertification and on Biodiversity all recognize the importance of SOC and point to the need for quantification of SOC stocks and changes. An understanding of SOC stocks and changes at the national and regional scale is necessary to further our understanding of the global C cycle, to assess the responses of terrestrial ecosystems to climate change and to aid policy makers in making land use/management decisions. Several studies have considered SOC stocks at the plot scale, but these are site specific and of limited value in making inferences about larger areas. Some studies have used empirical methods to estimate SOC stocks and changes at the regional scale, but such studies are limited in their ability to project future changes, and most have been carried out using temperate data sets. The computational method outlined by the Intergovernmental Panel on Climate Change (IPCC) has been used to estimate SOC stock changes at the regional scale in several studies, including a recent study considering five contrasting eco regions. This 'one step' approach fails to account for the dynamic manner in which SOC changes are likely to occur following changes in land use and land management. A dynamic modelling approach allows estimates to be made in a manner that accounts for the underlying processes leading to SOC change. Ecosystem models, designed for site scale applications can be linked to spatial databases, giving spatially explicit results that allow geographic areas of change in SOC stocks to be identified. Some studies have used variations on this approach to estimate SOC stock changes at the sub-national and national scale for areas of the USA and Europe and at the watershed scale for areas of Mexico and Cuba. However, a need remained for a national and regional scale, spatially explicit system that is generically applicable and can be applied to as wide a range of soil types, climates and land uses as possible. The Global Environment Facility Soil Organic Carbon (GEFSOC) Modelling System was developed in response to this need. The GEFSOC system allows estimates of SOC stocks and changes to be made for diverse conditions, providing essential information for countries wishing to take part in an emerging C market, and bringing us closer to an understanding of the future role of soils in the global C cycle. (C) 2007 Elsevier B.V. All rights reserved.

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Temporal and spatial variability of aerosol optical depth (AOD) are examined using observations of direct solar radiation in the Eurasian Arctic for 1940-1990. AOD is estimated using empirical methods for 14 stations located between 66.2 degrees N and 80.6 degrees N, from the Kara Sea to the Chukchi Sea. While AOD exhibits a well-known springtime maximum and summertime minimum at all stations, atmospheric turbidity is higher in spring in the western (Kara-Laptev) part of the Eurasian Arctic. Between June and August, the eastern (East Siberian-Chukchi) sector experiences higher transparency than the western part. A statistically significant positive trend in AOD was observed in the Kara-Laptev sector between the late 1950s and the early 1930s predominantly in spring when pollution-derived aerosol dominates the Arctic atmosphere but not in the eastern sector. Although all stations are remote, those with positive trends are located closer to the anthropogenic sources of air pollution. By contrast, a widespread decline in AOD was observed between 1982 and 1990 in the eastern Arctic in spring but was limited to two sites in the western Arctic. These results suggest that the post-1982 decline in anthropogenic emissions in Europe and the former Soviet Union has had a limited effect on aerosol load in the Arctic. The post-1982 negative trends in AOD in summer, when marine aerosol is present in the atmosphere, were more common in the west. The relationships between AOD and atmospheric circulation are examined using a synoptic climatology approach. In spring, AOD depends primarily on the strength and direction of air flow. Thus strong westerly and northerly flows result in low AOD values in the East Siberian-Chukchi sector. By contrast, strong southerly flow associated with the passage of depressions results in high A OD in the Kara-Laptev sector and trajectory analysis points to the contribution of industrial regions of the sub-Arctic. In summer, low pressure gradient or anticyclonic conditions result in high atmospheric turbidity. The frequency of this weather type has declined significantly since the early 1980s in the Kara-Laptev sector, which partly explains the decline in summer AOD values. (c) 2004 Elsevier B.V. All rights reserved.

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Experimental philosophy brings empirical methods to philosophy. These methods are used to probe how people think about philosophically interesting things such as knowledge, morality, freedom, etc. This paper explores the contribution that qualitative methods have to make in this enterprise. I argue that qualitative methods have the potential to make a much greater contribution than they have so far. Along the way, I acknowledge a few types of resistance that proponents of qualitative methods in experimental philosophy might encounter, and provide reasons to think they are ill-founded.