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This thesis looks at the engineering aspects of silkworm cocoons as a structural biological composite system. A wide range of species of silk cocoons were studied for their morphologies, physical properties and mechanical behaviour. A silk cocoon can be described very broadly as a nonwoven fibre composite made of silk fibres bonded by sericin binder, although the a variety of species can show a diversity of structural features of the layers, porosity, degree of orientation, binding density and presence of crystals etc. These structural differences lead to diverse cocoon mechanical behaviour. Tensile and compressive properties of cocoons are tested and linked to their individual interfibre bonding, connectivity and density. Gas diffusion through the cocoon walls is controlled by the combination of thickness and density. In addition, a physically realistic quantitative model is developed, which links directly the structure and mechanical properties of silk cocoons. The gradual loss of connectivity of the interfibre bonding is the key mechanism for the deformation of cocoons. It can be quantified as a strain activated function of the bonding up to a failure criterion, where either a percolation threshold of 50% of these bonds or the failure stress of the binder arrives. For Bombyx mori cocoon, which has a graded-layer structure, the model was enhanced to include the contribution of interlayer and intralayer bonding in the system. This model can also be applied to other nonwoven fibre and particulate composites using a small number of physically realistic model parameters, and will be a valuable ‘bioinspired’ tool for the development of new composite systems. Based on the understanding of structure-mechanical property relationships in silkworm cocoons, an engineering approach was used for examining cocoon as an impact resistant structural material that provides mechanical protection from environmental threats. In addition, silk cocoons were used as a nonwoven reinforcement to develop an engineering composite by increasing the connectivity (more binder) in the cocoon. Using polyurethane or regenerated silk fibroin of medium concentration can increase the toughness of cocoons, and epoxy or regenerated silk fibroin of high concentration binding leads to a brittle system.

Sericulture is an important agro industry in Indian economy. Reeling sector is a vital component of sericulture linking the agriculture based activity of cocoon production with the industrial activity of fabric production. Reeling converts the cocoons into raw silk yam. Karnataka contributes about 63% of the silk production of the country and therefore the present study is focused on the silk reeling industry of Karnataka. Silk reeling sector, though provides a vital transformation, appear to be the weakest link owing to its innumerable problems and the limited value addition that takes place. Problems are associated with raw material availability, working capital constraints, marketing and quality related aspects. Reeling sector is input dependent activity and its operations are influenced heavily by three factors viz., cocoon quality, cocoon price and cocoon supply. However, there has not been adequate thrust on quality due to the absence of quality based price fixation. Absence of quality based pricing has been a major deterrent factor in the pursuit for quality improvement. The seasonality associated with cocoon quality, cocoon supply and price as also the raw silk price almost always determine the fate of reeling activity. Being aware of the limited research done in respect of Indian silk industry, an elaborate literature review in the area of economics and management aspects of the silk industry in general and silk reeling operations in particular, was made. Studies on the economics of reeling operations done in the past indicate negative net revenue for the reeling units. However, if the reeling industry has survived over the years, it cannot be in spite of the loss. The industry has to breakeven over a period of time to consolidate the gains, however meagre. So, it is worthwhile to study the economics of silk reeling industry over a sufficient period of time, that is enough to include a cycle of seasonality, be it with respect to cocoon quality, cocoon availability, cocoon price, raw silk demand or raw silk price. In addition, if the element of uncertainties at varying points of time is included to study their effect on reeling economics, it makes the study more meaningful. It may be noted that, the variations in cocoon price over a period of time are dictated by the seasonality with respect to cocoon supply and demand. With regard to the variations in cocoon price at a given point of time (within a season), price differential between the cocoon lots appears to be largely due to its quality. A study of the inter relationship between cocoon quality, its quantity and price as also raw silk price is important. It is therefore felt that, the relationship between the cost of cocoons, cocoon quality and its productivity, when built into the determination of reeling economics, the analysis will be more realistic. A study of a typical reeling unit, to unearth the intricacies of operations and decision-making in the light of the volatile situation in the industry forms a pre requisite for a clear understanding of its functioning. Since reeling activity is highly input dependent, ignoring the aspects of the input market dynamics would not yield a holistic perspective of the operations. If one has to study and understand the market dynamics, the attributes of the commodity transacted should be clearly known. The commodity in question here is cocoon. The quality of cocoons does not have a unique expression, either to consider as a variable for studying the relationships in the market or as an input into the production process or as a yardstick for commercial transactions. The thesis thus deals with three major aspects of silk reeling industry in Karnataka, relating to the quality of raw material, dynamics of market transactions and analysis of the day to day operations of a typical silk reeling unit. There are around five quality parameters used for testing the quality of cocoons and each of them has a certain dimension of importance in defining the quality of cocoons. The procedures followed in Japan and China are not readily adaptable for Indian conditions. Therefore, an attempt has been made to develop a unique measure of cocoon quality under Indian conditions both from the point of view of appropriateness of representation as also the ease of determination commercially. In view of the importance of shell ratio 9c (SR%) and defective cocoon % (DC%) in representing the quality of cocoons, these two quality parameters are used for fixing the cocoon quality index. The statistical technique chosen for developing the Cocoon Quality Index (CQI) is discriminant analysis. Data on SR% and DC9c in respect of a sample of around 40,000 lots of multibi cocoons spanning a period of two years were collected for the analysis. The objective was to group the cocoons into low, medium and high quality in addition to arriving at a discriminant function to represent the quality index from SR% and DC% as independent variables. The analysis has contributed in establishing an index for assessing and grading the quality of, both mutibi and bivoltine cocoons in the Indian context. The study has also brought to focus the fact that, SR% and DC% adequately represent the quality of cocoons. As an extension of the objective, the commercial application of CQI as a means of price fixation mechanism in the cocoon markets has been illustrated. An analysis of the quality of cocoon lots presently being transacted in Karnataka has been made. The study of the market dynamics focused first on estimation of the relationship between cocoon price and its quality and supply (quantity) and then establishment of the causal relationship between cocoon price and silk price. Day wise aggregate data were used in. these two instances. In addition, the relationship between lot size, quality and price of cocoons being transacted in the cocoon markets has been established using the lot wise micro level data. The interrelationships of the various time series data have been studied through ARIMA analysis. The asymmetry in response of raw silk price to changes in cocoon price has been studied. The study enabled the identification of the determinants of cocoon price and raw silk price which are the major factors contributing to the revenue of a silk reeling unit. The capability of the buyers to assess the quality of cocoons subjectively even in the absence of an analytical system, speaks about the experience and expertise of the reelers. The supply quantity of cocoons largely influences the cocoon price. The dependence of raw silk price on cocoon price indicates the predominance of the supply side of the industry. The symmetry in the response of raw silk price to changes in cocoon price has also been established. The problems typical of a reeling unit merit the application of simulation technique in order to gain insights into the operations of a reeling unit. Discrete Event System Simulation has been used with fixed time increment approach and terminating criteria. The operations of a typical silk reeling unit have been simulated for a period of one whole year. A typical model based on the heuristic thinking of reelers to reflect the practices ingrained in the reeling units has been developed. The strategies they adopt to counter the vagaries of their operations have also been considered. Silk reeling being an input controlled industry, the heuristics of cocoon buying decision has been incorporated as the core of the model. The heuristics are derived from discussions with several prominent reelers and observation of their operations. The model tries to incorporate the volatile situation of the cocoon market and the raw silk sale price as also the constraints of working capital and the decision the reeler tends to take under these conditions. Standard procedures of simulation viz., variance reduction techniques, verification and validation of simulation model etc. have been followed. Simulation experiments have been made considering the factors of strategies, working capital borrowed money and installed capacity, in order to study its influence on the performance of a reeling unit. The simulation experimental data have been initially subjected to rnultivariate analysis and later to univariate ANOVA for each of the two response variables viz., cumulative net revenue and cumulative capacity utilisation. The unique relationship between revenue and capacity utilisation indicated a trade-off between the two. The reeling unit has to aim at maximising utilisation without major setbacks in revenue. It has been found that the capacity utilisation of a reeling unit is influenced more significantly by the factors or parameters of the model viz., strategy, working capital, and borrowed money and plant capacity, while the variables of the model viz., cocoon price, CQI and raw silk price influence cumulative net revenue. The importance of cocoon quality for better economics of production has been clearly established which should serve as a guiding factor for cocoon buying decision. An interesting result is that when there is adequate working capital, a bigger batch size for raw silk sales earns higher net revenue. The seasonality in net revenue is overwhelming in all the cases. The reeling unit has positive net revenue in the first six months with a few ups and downs and the gain it had consolidated slowly reduces before stabilising at a relatively lower level. The important contributions are the development of a quality index for grading of cocoons, establishment of the interrelationships among cocoon price, its quality and supply quantity as also the relationship between cocoon price and raw silk price. The much needed insight into the operations of a reeling unit has been provided by the simulation analysis. For the first time it has been established that, reeling units do make profits from the primary product. The model incorporated good management decision making for the purchase of cocoons and handling of working capital and other operations.

[Truncated abstract] This thesis explores the ecophysiology of cocooning and non-cocooning Australian burrowing desert frogs in order to specify the details of these two alternative survival strategies. Many details of these life-history strategies have not previously been determined for Australian frogs. In this study the detailed method of function and formation of the cocoon itself was investigated for the first time, as were the moulting cycles, which drive cocoon formation. Cocooning species had consistently shorter inter-moult-periods than non-cocooning species, which is presumably adaptive, allowing production of cocoon layers at a faster rate. Transmission electron microscopy revealed cocoon formation in Cyclorana platycephala to be a plastic, rather than static adaptation. The initial stages of cocoon formation appear to be the most critical. Cocoon layer formation is fastest in the first month and the initial layers produced are thicker than subsequent layers. Also, only in this initial stage does layer thickness appear to be influenced by soil moisture. Scanning electron microscopy confirmed the lips, eyelids and cloaca of cocooned frogs to be sealed by continuous layers of cocoon. However, it remains unclear precisely how the continuous junctions between cells from discreet sources, such as the upper and lower lip, are formed. Measurements of evaporative water loss and resistance over various relative humidity gradients suggested that water content within the cocoon structure is very low unless the external RH is > 93%. Therefore, anuran cocoon is confirmed to function as a specialised and highly effective barrier to water diffusion in arid-zone frogs. ... Within a dune swale, N. aquilonius burrows were an average depth of 1.13 m in loamy sand (clay = 6%, silt = 7%). Neobatrachus aquilonius excavated from the claypan had well formed cocoons, while those found in the dune swale had only one or two thin layers, indicating cocoon formation had only just commenced, although the last rainfall had been over six months prior. This suggests that N. aquilonius is able to switch between the cocooning and non-cocooning strategy in different soil types and different conditions. In summary, cocoon formation was found not to be an entirely passive accumulation of layers. Cocoon formation involved specialisation in the rate and thickness of epithelial layer production and the sealing of layers over lips, eyes and cloaca. Moreover, the cocoon was confirmed to operate effectively as a diffusion barrier at all except the highest external relative humidity. Like cocoon-forming species, Notaden nichollsi was found to metabolically depress to survive for longer periods underground. However, they cannot survive for the entire period

Cette thèse porte sur la Conception Centrée Valeur (CCV) proposé par Gilbert Cockton dans le but d'aller au-delà de l'utilisabilité dans les systèmes interactifs. L'auteur propose un canevas pour la mise en oeuvre de la CCV. Cependant, les opérationnalisations restent partielles et sont réalisées par lui-même, d'où un manque de recul de la communauté vis-à-vis de la méthode. La thèse relate la conception centrée valeur de Cocoon, un système d'information mobile et sensible au contexte. Elle apporte des contributions à la fois sur les plans conceptuel et méthodologique. D'un point de vue conceptuel, elle introduit la taxonomie PIPE (Personnelle, Impersonnelle, Pérenne, Éphémère) pour la caractérisation de l'information. En outre, elle montre que les systèmes existants ne couvrent pas PIPE : ils sont surtout focalisés sur les informations impersonnelles. Alors, la thèse propose le concept d'arbre de vie et Cocoon. D'un point de vue méthodologique, la thèse apporte une compréhension meilleure de la notion de valeur. En outre, elle fournit un retour d'expérience sur la CCV accompagné de remarques et recommandations pour des mises en oeuvres futures plus performantes. Enfin, elle propose un canevas pour la construction des cartes de valeur et une stratégie pour l'estimation de la valeur. / The thesis deals with Worth Centered Design (WCD) introduced by Gilbert Cockton. The author also introduced a framework aimed to support the WCD operationalization. However, this framework has been operationalized only partially until now and by Gilbert Cockton himself. The thesis relates our WCD experience with Cocoon, a mobile and context-aware information system. The thesis contributions are both conceptual and methodological. From a conceptual point of view, we introduce the PIPE (Personal, Impersonal, Perennial, Ephemeral) taxonomy for information characterization and show that existing systems only partially covers the PIPE information space: they focus on impersonal information. This notice motivated us to propose the life tree concept and Cocoon. From a methodological point of view, we offer a feedback to the community on an interesting concept method as well as recommendations for more efficient operationalizations. In addition, we introduce a framework for worth maps construction and a strategy for worth assessment.

Os resultados obtidos nesta tese podem ser distribuídos em três grupos: composição química da hemolinfa e do casulo coletivo e determinação química de alguns componentes principais do corpo gorduroso e túbulos de Malpighi ao longo do desenvolvimento. Os principais resultados referentes à química da hemolinfa de larvas maduras são: 1) A hemolinfa possui uma densidade 1,043, pH = 7,27, osmolaridade = 216 miliosmoles e corresponde a 37% do pêso-úmido do animal e 26% de seu pêso-sêco. A hemolinfa não se coagula e possui um volume de células correspondente a 0,3% de seu volume total. 2) A análise química realizada deu conta de 88% do peso-sêco total da hemolinfa e revelou que entre os componentes presentes mais importantes em massa estão as proteínas, seguidas dos aminoácidos livres, enquanto que os osmóticamente mais ativos são os aminoácidos livres seguido de Mg++ e Na+. Entre os aminoácidos é notável a presença de ornitina e cistationina em concentrações relativamente elevadas e a ausência, mesmo em traços, de cisteína e/ou cistina e citrulina. 3) Os peptídeos ocorrem em concentrações elevadas, mas em pequeno número, e são compostos de 2 a 3 resíduos de aminoácidos em média; o mais abundante dos quais deve ser um dipeptídeo de histidina e ácido aspártico. 4) Citrato é o ânion mais importante da hemolinfa, seguido dos fosfatos orgânicos, enquanto que trealose é o principal carboidrato presente. 5) Existem pelo menos 6 carotenóides ligados de forma não covalente a proteínas da hemolinfa e uma cromoglicoproteína, de côr amarelo-limão, fluorescente, de natureza desconhecida. Os carotenóides mais importantes quantitativamente são: β-caroteno e um similar ao astaceno. A composição em massa do casulo coletivo na véspera da muda pupal é a seguinte, em números inteiros: 44% de CaCO3; 34% de proteínas e 10% de carboidratos, ambos insolúveis em todos solventes utilizados (SDS 10%, uréia 6M, ácido fórmico 50%, HCl 2N, KOH 1M e Na HCO3 1M); 10% de material hidrossolúvel 4% de cinzas não identificadas. O material hidrossolúvel foi parcialmente identificado como: proteína (4%), carboidratos (2%), enquanto que 4% ainda permanece desconhecido. O correlacionamento da análise química da hemolinfa, casulo, túbulos de Malpighi e corpo gorduroso ao longo do desenvolvimento, possibilitou ainda as seguintes conclusões: 1) A fração insolúvel do casulo (proteínas e carboidratos) corresponde à sêda secretada pelas glândulas salivares da larva, enquanto que o CaCO3 presente provém dos túbulos de Malpighi. 2) As proteínas do casulo devem originar-se, pelo menos em parte, das proteínas da hemolinfa, enquanto que seus carboidratos devem provir do glicogênio do corpo gorduroso. Os resultados são considerados em têrmos de seus possíveis significados metabólicos e eventualmente fisiológicos. Ênfase é dada na discussão do papel metabólico dos componentes orgânicos e inorgânicos da hemolinfa, assim como dos mecanismos de secreção da sêda e CaCO3 e sua possível regulação hormonal. / The results of this thesis are concerned to three main lines of research: the chemical composition of the hemolymph, of the communal cocoon, and the chemical determination of some components in the rat body and Malpighian tubules along larval development. The chief results on the hemolymph chemistry of mature larvae are: 1) The hemolymph has a density = 1.043, pH = 7.27, osmolarity = 2l6 miliosmols and corresponds to 37% of the larva (Wet-Weight) or to 26% of the larva (dry weight). The hemolymph does not clott and the volume of the hemocytes is 0.3% of blood total volume. 2) The chemical analysis dealt with 88% (dry-weight) of the hemolymph and showed that proteins are the most important component in mass, while free amino acids, Mg++ and Na+ are the most osmotically active substances. Among the amino acids is remarkable the titres of ornithine and cystathionine, and the complete absence of cysteine and/or cystine and citrulline. 3) There are few peptides, but present in high titres. They are built of two to three amino acids residues, and the most concentrated of them must be a dipeptide of histidine and aspartic acid. 4) Citrate and organic phosphates are the most important anions in the hemolymph. Trehalose is the chief carbohydrate present. 5) There are at least 6 non-covalentely protein-bound carotenoids and one lemon-yellow, fluorescent chromoglycoprotein of unknown nature. The chemical composition of the communal cocoon of R. americana expressed in percentage of its total dry weigth (numbers rounded to the nearest unity) are: 44% of CaCO3; 34% of proteins and 10% of carbohydrates both insoluble in all solvents used (10% SDS, 6M urea, 50% formic acid, 2N HCl, 1M KOH and 1M NaHCO3 ); 10% of water soluble material and 4% of unknown nature. The water soluble material was identified in part as: protein (4%) and carbohydrates (2%), while 4% remained unknown. The interrelationship among the results of the chemical analysis of the hemolymph, cocoon, Malpighian tubules and fat body during larval development was used to draw the conclusions: 1) The insoluble fraction of the cocoon proteins and carbohydrates) corresponds to the silk produced by the larval salivary glands, while CaCO3 comes from Malpighian tubules. 2) The cocoon proteins must come, at least in part, from the hemolymph proteins, while its carbohydrates must come from the fat body glycogen. The results are discussed in terms of its possible metabolic and eventually physiological meanings. Emphasis is given in the discussion of the metabolic role of the inorganic and organic components of the hemolymph, as yet in the the mechanisms of the silk secretion and CaCO3 deposition and their possible hormonal regulation.

Os resultados obtidos nesta tese podem ser distribuídos em três grupos: composição química da hemolinfa e do casulo coletivo e determinação química de alguns componentes principais do corpo gorduroso e túbulos de Malpighi ao longo do desenvolvimento. Os principais resultados referentes à química da hemolinfa de larvas maduras são: 1) A hemolinfa possui uma densidade 1,043, pH = 7,27, osmolaridade = 216 miliosmoles e corresponde a 37% do pêso-úmido do animal e 26% de seu pêso-sêco. A hemolinfa não se coagula e possui um volume de células correspondente a 0,3% de seu volume total. 2) A análise química realizada deu conta de 88% do peso-sêco total da hemolinfa e revelou que entre os componentes presentes mais importantes em massa estão as proteínas, seguidas dos aminoácidos livres, enquanto que os osmóticamente mais ativos são os aminoácidos livres seguido de Mg++ e Na+. Entre os aminoácidos é notável a presença de ornitina e cistationina em concentrações relativamente elevadas e a ausência, mesmo em traços, de cisteína e/ou cistina e citrulina. 3) Os peptídeos ocorrem em concentrações elevadas, mas em pequeno número, e são compostos de 2 a 3 resíduos de aminoácidos em média; o mais abundante dos quais deve ser um dipeptídeo de histidina e ácido aspártico. 4) Citrato é o ânion mais importante da hemolinfa, seguido dos fosfatos orgânicos, enquanto que trealose é o principal carboidrato presente. 5) Existem pelo menos 6 carotenóides ligados de forma não covalente a proteínas da hemolinfa e uma cromoglicoproteína, de côr amarelo-limão, fluorescente, de natureza desconhecida. Os carotenóides mais importantes quantitativamente são: β-caroteno e um similar ao astaceno. A composição em massa do casulo coletivo na véspera da muda pupal é a seguinte, em números inteiros: 44% de CaCO3; 34% de proteínas e 10% de carboidratos, ambos insolúveis em todos solventes utilizados (SDS 10%, uréia 6M, ácido fórmico 50%, HCl 2N, KOH 1M e Na HCO3 1M); 10% de material hidrossolúvel 4% de cinzas não identificadas. O material hidrossolúvel foi parcialmente identificado como: proteína (4%), carboidratos (2%), enquanto que 4% ainda permanece desconhecido. O correlacionamento da análise química da hemolinfa, casulo, túbulos de Malpighi e corpo gorduroso ao longo do desenvolvimento, possibilitou ainda as seguintes conclusões: 1) A fração insolúvel do casulo (proteínas e carboidratos) corresponde à sêda secretada pelas glândulas salivares da larva, enquanto que o CaCO3 presente provém dos túbulos de Malpighi. 2) As proteínas do casulo devem originar-se, pelo menos em parte, das proteínas da hemolinfa, enquanto que seus carboidratos devem provir do glicogênio do corpo gorduroso. Os resultados são considerados em têrmos de seus possíveis significados metabólicos e eventualmente fisiológicos. Ênfase é dada na discussão do papel metabólico dos componentes orgânicos e inorgânicos da hemolinfa, assim como dos mecanismos de secreção da sêda e CaCO3 e sua possível regulação hormonal. / The results of this thesis are concerned to three main lines of research: the chemical composition of the hemolymph, of the communal cocoon, and the chemical determination of some components in the rat body and Malpighian tubules along larval development. The chief results on the hemolymph chemistry of mature larvae are: 1) The hemolymph has a density = 1.043, pH = 7.27, osmolarity = 2l6 miliosmols and corresponds to 37% of the larva (Wet-Weight) or to 26% of the larva (dry weight). The hemolymph does not clott and the volume of the hemocytes is 0.3% of blood total volume. 2) The chemical analysis dealt with 88% (dry-weight) of the hemolymph and showed that proteins are the most important component in mass, while free amino acids, Mg++ and Na+ are the most osmotically active substances. Among the amino acids is remarkable the titres of ornithine and cystathionine, and the complete absence of cysteine and/or cystine and citrulline. 3) There are few peptides, but present in high titres. They are built of two to three amino acids residues, and the most concentrated of them must be a dipeptide of histidine and aspartic acid. 4) Citrate and organic phosphates are the most important anions in the hemolymph. Trehalose is the chief carbohydrate present. 5) There are at least 6 non-covalentely protein-bound carotenoids and one lemon-yellow, fluorescent chromoglycoprotein of unknown nature. The chemical composition of the communal cocoon of R. americana expressed in percentage of its total dry weigth (numbers rounded to the nearest unity) are: 44% of CaCO3; 34% of proteins and 10% of carbohydrates both insoluble in all solvents used (10% SDS, 6M urea, 50% formic acid, 2N HCl, 1M KOH and 1M NaHCO3 ); 10% of water soluble material and 4% of unknown nature. The water soluble material was identified in part as: protein (4%) and carbohydrates (2%), while 4% remained unknown. The interrelationship among the results of the chemical analysis of the hemolymph, cocoon, Malpighian tubules and fat body during larval development was used to draw the conclusions: 1) The insoluble fraction of the cocoon proteins and carbohydrates) corresponds to the silk produced by the larval salivary glands, while CaCO3 comes from Malpighian tubules. 2) The cocoon proteins must come, at least in part, from the hemolymph proteins, while its carbohydrates must come from the fat body glycogen. The results are discussed in terms of its possible metabolic and eventually physiological meanings. Emphasis is given in the discussion of the metabolic role of the inorganic and organic components of the hemolymph, as yet in the the mechanisms of the silk secretion and CaCO3 deposition and their possible hormonal regulation.

This thesis investigates the mechanisms behind natural silk spinning by integrating rheology, spectroscopy and small angle scattering to better understand this process and to guide our efforts towards mimicking Nature’s ways of producing high performance fibres. As a result of natural selection, arthropods such as spiders and moths have evolved the ability to excrete silk proteins in a highly controlled manner. Spun from liquid feedstocks, silk fibres are used ex vivo to build structures with mechanical properties currently unmatched by industrial filaments. As yet, relatively little attention has been directed to the investigation of spinning under biologically relevant conditions. To better understand how and why silk is spun, this thesis bridges the gap between liquid silk flow properties and structure development. To directly connect the two, I have developed and deployed novel experimental platforms that combine infrared spectroscopy and small angle scattering with rheology. This approach has clarified long-standing ambiguities on the structural root of silk’s apparently complex flow properties. Small angle scattering revealed the length scales involved in the flow induced solidification under a range of spinning conditions. Mo reover, infrared spectroscopy offered a unique perspective into silk’s formation process immediately after excretion. In a similar manner to the post-extrusion tuning of the properties of partly solidified spider silk filaments, this thesis has revealed that silkworm silk fibres are far from completely formed once excreted. One might describe the filaments of mulberry silkworm as seeded molten polymers that form its hydrogen bonding network and crystallises slowly on site. Consequently, it enlightens that post-spinning conditions are equally paramount for silkworm silk, giving an explanation for the relatively poorer mechanical properties. The comparison of silks from a range of species, allowed this hypothesis to be extended to wild silkworm silk. My insights into spinning had the fortuitous repercussion of facilitating silk fibre solubilisation leading to the development of better artificial silk feedstocks flowing like native silks. With these findings, I believe we are now in an improved position to conceive artificial fibres with properties rivalling those of Nature.

<p>This thesis will look into what kind of solutions a company or a private person can use if they want to create a dynamic website using only free software. To do this we divided our work in two parts. In the first part, we developed a dynamic website for a Swedish company. On the server side we used exclusively free software with open source code. There are different meanings in how the term “free” should be used when referring to software, which we will explain in the thesis. We have also chosen to work with the XMLtechnology to see if it lives up to its expectations and to see if we could benefit from the technology. Alongside with the development of our site, another company developed a site for the same company as us, by using non-free software. We have described both implementations and compared them to see if it is possible to do the same thing with both free and non-free software. </p><p>The investigating part of our work consisted of getting information about what other people think about the free software phenomenon. To do so we created an online questionnaire where we randomly picked 100 Swedish web agencies and asked them to answer 8 questions about what kind of software they used in their company, and what they thought about free software. To get some more opinions we also interviewed two persons involved in these kinds of topics. Jan Sandred, who is a well known expert advisor in topics concerning the Information Technology area and Richard Stallman, the founder of GNU and the Free Software Movement. </p><p>The reason for dividing the thesis in two parts was to get an overall picture on the subject. We did not only want to base our results on other people’s thoughts. We wanted to make our own conclusions based on the implementation we did. This approach showed out to be very good. We got to try working with free software ourselves to see its pros and cons and build our own opinions about it. We could then proceed to compare our impressions to other people’s impressions about free software.</p>

Cette thèse porte sur la Conception Centrée Valeur (CCV) proposé par Gilbert Cockton dans le but d'aller au-delà de l'utilisabilité dans les systèmes interactifs. L'auteur propose un canevas pour la mise en oeuvre de la CCV. Cependant, les opérationnalisations restent partielles et sont réalisées par lui-même, d'où un manque de recul de la communauté vis-à-vis de la méthode. La thèse relate la conception centrée valeur de Cocoon, un système d'information mobile et sensible au contexte. Elle apporte des contributions à la fois sur les plans conceptuel et méthodologique. D'un point de vue conceptuel, elle introduit la taxonomie PIPE (Personnelle, Impersonnelle, Pérenne, Éphémère) pour la caractérisation de l'information. En outre, elle montre que les systèmes existants ne couvrent pas PIPE : ils sont surtout focalisés sur les informations impersonnelles. Alors, la thèse propose le concept d'arbre de vie et Cocoon. D'un point de vue méthodologique, la thèse apporte une compréhension meilleure de la notion de valeur. En outre, elle fournit un retour d'expérience sur la CCV accompagné de remarques et recommandations pour des mises en oeuvres futures plus performantes. Enfin, elle propose un canevas pour la construction des cartes de valeur et une stratégie pour l'estimation de la valeur.