Valuing of firm's prior knowledge: A measure of knowledge distance

Knowledge, especially scientific and technological knowledge, grows according to knowledge trajectories and guideposts that make up the prior knowledge of an organization. We argue that these knowledge structures and their specific components lead to successful innovation. A firm's prior knowledge facilitates the absorption of new knowledge, thereby renewing a firm's systematic search, transfer and acquisition of knowledge and capabilities. In particular, the exponential growth in biotechnology is characterized by the convergence of disparate scientific and technological knowledge resources. This paper examines the shift from protein-based to DNA-based diagnostic technologies as an example, to quantify the value of a firm's prior knowledge using relative values of knowledge distance. The distance between core prior knowledge and the rate of transition from one knowledge system to another has been identified as a proxy for the value a firm's prior knowledge. The overall difficulty of transition from one technology paradigm to another is discussed. We argue this transition is possible when the knowledge distance is minimal and the transition process has a correspondingly high value of absorptive capacities. Our findings show knowledge distance is a determinant of the feasibility, continuity and capture of scientific and technological knowledge. Copyright © 2003 John Wiley & Sons, Ltd.

Compression Efficiency Analysis of Wyner-Ziv Video Coding with Motion Compensated Side Information Interpolation

The Wyner-Ziv video coding (WZVC) rate distortion performance is highly dependent on the quality of the side information, an estimation of the original frame, created at the decoder. This paper, characterizes the WZVC efficiency when motion compensated frame interpolation (MCFI) techniques are used to generate the side information, a difficult problem in WZVC especially because the decoder only has available some reference decoded frames. The proposed WZVC compression efficiency rate model relates the power spectral of the estimation error to the accuracy of the MCFI motion field. Then, some interesting conclusions may be derived related to the impact of the motion field smoothness and the correlation to the true motion trajectories on the compression performance.

A fractional approach for the motion planning of redundant and hyper-redundant manipulators

The trajectory planning of redundant robots through the pseudoinverse control leads to undesirable drift in the joint space. This paper presents a new technique to solve the inverse kinematics problem of redundant manipulators, which uses a fractional differential of order α to control the joint positions. Two performance measures are defined to examine the strength and weakness of the proposed method. The positional error index measures the precision of the manipulator's end-effector at the target position. The repeatability performance index is adopted to evaluate if the joint positions are repetitive when the manipulator execute repetitive trajectories in the operational workspace. Redundant and hyper-redundant planar manipulators reveal that it is possible to choose in a large range of possible values of α in order to get repetitive trajectories in the joint space.

Application of robust fixed point transformations for technological operation of robots

A robot’s drive has to exert appropriate driving forces that can keep its arm and end effector at the proper position, velocity and acceleration, and simultaneously has to compensate for the effects of the contact forces arising between the tool and the workpiece depending on the needs of the actual technological operation. Balancing the effects of a priori unknown external disturbance forces and the inaccuracies of the available dynamic model of the robot is also important. Technological tasks requiring well prescribed end effector trajectories and contact forces simultaneously are challenging control problems that can be tackled in various manners.

Knowledge discovery from trajectories

Dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geospatial Technologies

Embracing transience and subjectivity in the conservation of complex contemporary artworks: contributions from ethnographic and psychological paradigms

Dissertação para obtenção do Grau de Mestre em Conservação e Restauro, Perfil Ciências da Conservação Especialização em Arte Contemporânea

Impact of chromossomal structure on the evolution of Schizosaccharomyces pombe undergoing Mutation Accumulation

Large chromosomal rearrangements are common in natural populations and thought to be involved in speciation events. In this project, we used experimental evolution to determine how the speed of evolution and the type of accumulated mutations depend on the ancestral chromosomal structure and genotype. We utilized two Wild Type strains and a set of genetically engineered Schizosaccharomyces pombe strains, different solely in the presence of a certain type of chromosomal variant (inversions or translocations), along with respective controls. Previous research has shown that these chromosomal variants have different fitness levels in several environments, probably due to changes in the gene expression along the genome. These strains were propagated in the laboratory at very low population sizes, in which we expect natural selection to be less efficient at purging deleterious mutations. We then measured these strains’ changes in fitness throughout this accumulation of deleterious mutations, comparing the evolutionary trajectories in the different rearrangements to understand if the chromosomal structure affected the speed of evolution. We also tested these mutations for possible epistatic effects and estimated their parameters: the number of arising deleterious mutations per generation (Ud) and each one’s mean effect (sd).

Understanding the dispersion of fillers in polymer matrices

Understanding the mixing process of complex composite materials is fundamental in several industrial processes. For instance, the dispersion of fillers in polymer melt matrices is commonly employed to manufacture polymer composites, using a twin-screw extruder. The effectiveness of the filler dispersion depends not only on the complex flow patterns generated, but also on the polymer melt rheological behavior. Therefore, the availability of a numerical tool able to predict mixing, taking into account both fluid and particles phases would be very useful to increase the process insight, and thus provide useful guidelines for its optimization. In this work, a new Eulerian-Lagrangian numerical solver is developed OpenFOAM® computational library, and used to better understand the mechanisms determining the dispersion of fillers in polymer matrices. Particular attention will be given to the effect of the rheological model used to represent the fluid behavior, on the level of dispersion obtained. For the Eulerian phase the averaged volume fraction governing equations (conservation of mass and linear momentum) are used to describe the fluid behavior. In the case of the Lagrangian phase, Newton’s second law of motion is used to compute the particles trajectories and velocity. To study the effect of fluid behavior on the filler dispersion, several systems are modeled considering different fluid types (generalized Newtonian or viscoelastic) and particles volume fraction and size. The results obtained are used to correlate the fluid and particle characteristics on the effectiveness of mixing and morphology obtained.

Generating timed trajectories foran autonomous robot

Tese de Doutoramento Programa Doutoral em Engenharia Electrónica e Computadores

Review of robotic technology for keyhole transcranial stereotactic neurosurgery

The research of stereotactic apparatus to guide surgical devices began in 1908, yet a major part of today's stereotactic neurosurgeries still rely on stereotactic frames developed almost half a century ago. Robots excel at handling spatial information, and are, thus, obvious candidates in the guidance of instrumentation along precisely planned trajectories. In this review, we introduce the concept of stereotaxy and describe a standard stereotactic neurosurgery. Neurosurgeons' expectations and demands regarding the role of robots as assistive tools are also addressed. We list the most successful robotic systems developed specifically for or capable of executing stereotactic neurosurgery. A critical review is presented for each robotic system, emphasizing the differences between them and detailing positive features and drawbacks. An analysis of the listed robotic system features is also undertaken, in the context of robotic application in stereotactic neurosurgery. Finally, we discuss the current perspective, and future directions of a robotic technology in this field. All robotic systems follow a very similar and structured workflow despite the technical differences that set them apart. No system unequivocally stands out as an absolute best. The trend of technological progress is pointing toward the development of miniaturized cost-effective solutions with more intuitive interfaces.

Development of an intelligent earthwork optimization system

Tese de Doutoramento em Engenharia Civil.

Diagnosis and therapeutics of pulmonary arteriovenous fistula in childhood. Case report and review of the literature

We report the case of a 3-year-old female patient, who, since birth, had cyanosis difficult to explain with usual diagnostic tests. The only findings on physical examination were cyanosis and clubbing of her fingers. Chest computerized tomography showed images of excessive attenuation in the right lung, which resembled arteriovenous fistulae that were later confirmed on cardiac catheterization. The fistulous trajectories were then embolized with 7 Gianturco coils, which resulted in an immediate increase in the arterial saturation of blood oxygen.

Teaching clinical anatomy of the female pelvic floor to undergraduate students: A critical review of nevralgic points

Pelvic floor anatomy is complex and its three-dimensional organization is often difficult to understand for both undergrad- uate and postgraduate students. Here, we focused on several critical points that need to be considered when teaching the perineum. We have to deal with a mixed population of students and with a variety of interest. Yet, a perfect knowledge of the pelvic floor is the basis for any gynecologist and for any surgical intervention. Our objectives are several-fold; i) to estab- lish the objectives and the best way of teaching, ii) to identify and localize areas in the female pelvic floor that are suscepti- ble to generate problems in understanding the three-dimensional organization, iii) to create novel approaches by respecting the anatomical surroundings, and iv) prospectively, to identify elements that may create problems during surgery i.e. to have a closer look at nerve trajectories and on compression sites that may cause neuralgia or postoperative pain. A feedback from students concludes that they have difficulties to assimilate this much information, especially the different imaging tech- niques. Eventually, this will lead to a severe selection of what has to be taught and included in lectures or practicals. Another consequence is that more time to study prosected pelves needs to be given.

Sex biased spatial strategies relying on the integration of multimodal cues in a rat model of schizophrenia: impairment in predicting future context?

Male and female Wistar rats were treated postnatally (PND 5-16) with BSO (l-buthionine-(S,R)-sulfoximine) to provide a rat model of schizophrenia based on transient glutathione deficit. In the watermaze, BSO-treated male rats perform very efficiently in conditions where a diversity of visual information is continuously available during orientation trajectories [1]. Our hypothesis is that the treatment impairs proactive strategies anticipating future sensory information, while supporting a tight visual adjustment on memorized snapshots, i.e. compensatory reactive strategies. To test this hypothesis, BSO rats' performance was assessed in two conditions using an 8-arm radial maze task: a semi-transparent maze with no available view on the environment from maze centre [2], and a modified 2-parallel maze known to induce a neglect of the parallel pair in normal rats [3-5]. Male rats, but not females, were affected by the BSO treatment. In the semi-transparent maze, BSO males expressed a higher error rate, especially in completing the maze after an interruption. In the 2-parallel maze shape, BSO males, unlike controls, expressed no neglect of the parallel arms. This second result was in accord with a reactive strategy using accurate memory images of the contextual environment instead of a representation based on integrating relative directions. These results are coherent with a treatment-induced deficit in proactive decision strategy based on multimodal cognitive maps, compensated by accurate reactive adaptations based on the memory of local configurations. Control females did not express an efficient proactive capacity in the semi-transparent maze, neither did they show the significant neglect of the parallel arms, which might have masked the BSO induced effect. Their reduced sensitivity to BSO treatment is discussed with regard to a sex biased basal cognitive style.

Deciding where to belong: gender differences in educational trajectories and migration in a rural Spanish town

From an anthropological perspective, formal post-secondary schooling is not an abstractentity with an intrinsic value that everyone finds desirable, but rather one alternative among many that young people evaluate from their different positions in the social field. The problem discussed in this paper is the diverging life trajectories that young men and women in a concrete rural context, at the end of the 20th century, shape for themselves at the ages of 14-16, a moment of decision created by national legislation regarding mandatory education (LGE, 1970, General Education Law, and LOGSE, 1990, General Organic Law of the Education System). Despite a strong cultural norm of equal inheritance divided among all children, male and female, and despite the equal educational opportunities provided by the Spanish State, different meanings of possession and use-rights over land and the resulting culturally accepted gendered division of work converge to orient men and women differently towards post-secondary schooling. Observation of the age, gender, and civil status structure of the population led to the preliminary query: Why do men and women, in this town, behave differently with respect to migration and marriage? The main hypothesis was that women’s longer school trajectories and resulting migration and men’s anchoring in the town and their higher rates of celibacy were not drastic changes in values, in the positional-relational sense of Bourdieu (1988, 2002), but the current outcome of previously existing dissimilar relations to property that produce dissimilar mobility. Through their schooling and work choices, young men and women, at very early ages, locate themselves in, or decide to belong to, different contexts that later reveal very different possibilities of finding marriage partners. This paper is based on an ethnographic study of a small rural town (302 inhabitants in 1950; 193 in 2000) near Leon. Although this paper deals with the situation in the final decades of the 20th century, we must also consider the first half of the century, where some elements that shape this situation have their roots. Fieldwork was carried out between 1988 and 2001, in periods of differing length and intensity. The social subjects discussed here are the domestic unit and its component members. They were studied in conjunction, analyzing the life-trajectory decisions of specific persons in the framework of the domestic unit and the relations among people and property which comprise it. The tried-and-true methods of ethnographic research –participant observation, interviews, and life-histories, etc.- were employed. Archival research was also important for producing demographic data. Demographic analysis, the analysis of the composition and transformation of domestic units, and the creation of life trajectories were among the principal techniques used. The theoretical analysis was oriented by Bourdieu’s (2002) framework of the social field, habitus, and difference.