We study a stochastic particle system with a logarithmically-singular inter-particle interaction potential which allows for inelastic particle collisions. We relate the squared Bessel process to the evolution of localized clusters of particles, and develop a numerical method capable of detecting collisions of many point particles without the use of pairwise computations, or very refined adaptive timestepping. We show that when the system is in an appropriate parameter regime, the hydrodynamic limit of the empirical mass density of the system is a solution to a nonlinear Fokker-Planck equation, such as the Patlak-Keller-Segel (PKS) model, or its multispecies variant. We then show that the presented numerical method is well-suited for the simulation of the formation of finite-time singularities in the PKS, as well as PKS pre- and post-blow-up dynamics. Additionally, we present numerical evidence that blow-up with an increasing total second moment in the two species Keller-Segel system occurs with a linearly increasing second moment in one component, and a linearly decreasing second moment in the other component.

The interfacial adsorption and bulk properties of a collagenous polypeptide derived from chicken eggshell membranes, the 40 KDa polypeptide, and its mixtures with common low molecular weight (LMW) surfactants, SDS, DTAB and C10E8, have been studied for the first time using surface tension, ζ-potential, foam observations and neutron scattering techniques. The biopolymer has been shown to act as an effective biosurfactant by lowering the surface tension of water below the values commonly achieved with conventional LMW surfactants, i.e. γ = 32 ± 1 mN/m. This capability is maximized at its isoelectric point, pH ~5, and addition of NaCl does not have a major impact upon adsorption. On its own, the 40 KDa polypeptide lacks the ability to foam. When mixed with cationic and anionic surfactants, a positive synergy is observed at low concentrations of both materials that exceeds the expectations from the individual components due to the formation of polypeptide/surfactant complexes with high surface activity and high ability to foam and foam stability. At these concentrations, maximum interfacial adsorption is achieved. The synergy is observed in spite of the type of charges present in the surfactant polar head. However, under the conditions studied, there is a difference in behaviour in regards to colloidal stability and surface film formation between the mixed solutions with the anionic SDS and the cationic DTAB. The non-existence of the synergy in the surface adsorption profile of the mixtures of the polypeptide with the non-ionic surfactant C10E8, as obtained via the plate method, suggests that electrostatic interactions are necessary for this strong synergy to act. ζ-potential has been used to prove the electrostatic nature of the synergy. Specular neutron reflection and SANS measurements offered an insight into the complex size and structure. The 40 KDa polypeptide thus offers a promising alternative to the use of high amounts of LMW surfactants in a range of products in which low surface tension and/or high and stable volumes of foams are needed, by combining small amounts of polypeptide and an ionic surfactant. This could be exploited by industries which have an interest in nanoparticle formation such as personal care or pharmaceutical companies. However, further work is needed to fully characterize these interactions.

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2015-11-04T08:18:47Z No. of bitstreams: 1 texto completo.pdf: 7981213 bytes, checksum: aeec0f7b21a6f76f66efa6e3304727b3 (MD5) / Made available in DSpace on 2015-11-04T08:18:48Z (GMT). No. of bitstreams: 1 texto completo.pdf: 7981213 bytes, checksum: aeec0f7b21a6f76f66efa6e3304727b3 (MD5) Previous issue date: 2015-07-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A proteína NIK (NSP-interacting kinase), identificada por interagir com a proteína NSP (nuclear shuttle protein) de geminivírus, apresenta características estruturais, bioquímicas e biológicas condizentes com um autêntico receptor cinase envolvido na resposta de defesa à infecção por geminivírus. A ativação deste receptor imune resulta na fosforilação da proteína ribossomal L10 (RPL10) e na subsequente relocação nuclear desta proteína ribossomal. Apesar dos avanços obtidos com a identificação de RPL10, outras conexões moleculares que ligam a ativação de NIK à resposta antiviral ainda são desconhecidas, bem como a natureza deste mecanismo de defesa. Nesta investigação, foi identificado um novo componente efetor downstream da via de sinalização mediada por NIK, um fator de transcrição denominado LIMYB (L10-Interacting Myb domain-containing protein), isolado pela sua capacidade de interagir com RPL10 pelo sistema de duplo híbrido em leveduras. Ensaios de co-imunoprecipitação e de complementação de fluorescência bimolecular (BiFC) mostraram que o complexo RPL10-LIMYB ocorre estavelmente na planta, mais precisamente no núcleo das células vegetais. Estudos de caracterização funcional mostraram que LIMYB atua como um autêntico fator de transcrição, ligando-se ao promotor e inibindo a expressão de genes de proteínas ribossomais. Estes resultados sugerem que o mecanismo de defesa antiviral mediado por NIK baseia-se na supressão da tradução do hospedeiro. Para examinar esta hipótese, inicialmente foi avaliado os níveis de tradução em linhagens de tomate superexpressando um mutante superativo de AtNIK1 (T474D). Os resultados mostraram que as linhagens transgênicas apresentaram menor acúmulo de proteínas recentemente sintetizadas quando comparadas com plantas WT. Posteriormente, as linhagens de tomate superexpressando T474D foram infectadas com duas espécies de begomovírus altamente divergentes, ToYSV (Tomato yellow spot virus) e ToSRV (Tomato severe rugose virus). As linhagens transgênicas apresentaram sintomas atenuados ou foram assintomáticas. Estas observações foram associadas com um atraso na infecção viral, com taxas de infecção menores e com a redução no acúmulo de DNA viral em folhas sistêmicas infectadas. Apesar do fenótipo de tolerância exibido pelas linhagens superexpressando T474D e dos menores índices de síntese proteica, estas linhagens não apresentaram diferenças no desenvolvimento, no desempenho fisiológico e nas características horticulturais quando comparadas com plantas WT ou com linhagens superexpressando AtNIK1. Finalmente, foi determinado se a redução nos níveis de tradução global do hospedeiro causado pela superexpressão de T474D poderia prejudicar a síntese de proteínas virais. Para isto, frações polissomais foram isoladas a partir de linhagens WT e T474D infectadas com ToYSV e a presença de mRNA viral foi examinada nestas frações. Os resultados mostraram uma menor associação do mRNA que codifica a proteína do capsídeo viral nas frações de polissomos de linhagens T474D quando comparadas àquelas de linhagens não transformadas. Coletivamente, estes resultados indicam que begomovírus não são capazes de manter altos níveis de tradução de mRNA virais nas linhagens superexpressando o mutante T474D, indicando que a supressão global da síntese de proteínas, identificada nestes genótipos, pode proteger eficientemente as células contra a infecção por estes vírus. Entretanto, estudos da variação global na expressão gênica de plantas nik1 alelos nulos mostraram que a perda da função de NIK1 promoveu a indução de componentes do hub principal da sinalização a brassinosteróide e de hubs envolvidos na sinalização ao ácido salicílico e na imunidade antibacteriana. Estes resultados sugerem que NIK1 pode funcionar como um regulador negativo em vias de sinalização de desenvolvimento e imunidade, apesar de sua propriedade antiviral. / The NSP-interacting kinase (NIK) protein, identified through interaction with the geminivirus nuclear shuttle protein (NSP), displays structural, biochemical and biological characteristics consistent with an authentic receptor kinase involved in defense response against geminivirus infection. The activation of this immune receptor leads to phosphorilation of the ribosomal protein L10 (RPL10) and in the subsequent nuclear relocation of this ribosomal protein. Apart from the identification of RPL10 as a downtream component of the defense signaling, others molecular connections that link the NIK activation to the antiviral response, as well as the nature of this defense mechanism, remain to be determined. In this investigation, a new downstream effector component of the NIK-mediated signaling pathway, a transcription fator designated LIMYB (L10-Interacting Myb domain-containing protein), was identified by its capacity to interact with RPL10 through yeast two-hybrid system. Co-immunoprecipitation and bimolecular fluorescence complementation assays showed that RPL10-LIMYB complex occurs stably in the plant, specifically in the nucleus of plant cells. Functional characterization studies showed that LIMYB acts as an authentic transcription fator, binding to and inhibiting expression of ribosomal protein promoters. These results suggest that NIK-mediated antiviral defense mechanism is based on host translation suppression. To examine this hypothesis, the translation levels in tomato lines overexpressing the constitutively active mutant of AtNIK1 (T474D) was initially assessed. The results demonstrated that transgenic lines had lower accumulation of newly synthesized proteins when comparated to WT plants. Subsequently, T474D-overexpressing tomato lines were infected with two highly divergent begomovirus species, ToYSV (Tomato yellow spot virus) and ToSRV (Tomato severe rugose virus). The transgenic lines either displayed attenuated symptons or were asymptomatic. These findings were associated with delay in viral infections, lower infection rates and reduction in viral DNA accumulation in systemically infected leaves. Despite the tolerance phenotype and lower rates of protein synthesis displayed by T474D-overexpressing lines, no difference in the development, physiological performance and horticultural traits was observed between T474D-overexpressing and WT or AtNIK1-overexpressing lines. Finally, whether the reduction in overall levels of host translation caused by overexpression of T474D could affect the viral proteins synthesis was examined. For this purpose, polysomal fractions were isolated from WT and T474D lines infected with ToYSV and examined for the presence of viral mRNA. The results showed lower association of mRNA encoding viral capsid protein at the polysomes fractions of T474D lines when comparated to that of untransformed lines. Collectively, these results indicate that begomovirus are not able to maintain high levels of viral mRNA translation into T474D-overexpressing lines, indicating that the global suppression of the protein synthesis identified in these genotypes may efficiently protect cells against infection by these virus. However, studies of global changes in gene expression of nik1 null alleles revealed that loss of NIK1 function promoted induction of components of the main brassinosteroid signaling hub and of hubs involved in salicylic acid signaling and antibacterial immunity. These results suggest that NIK1 may function as a negative regulator in development and immunity signaling pathways, despite its antiviral property.

O conceito de que estimulação elétrica promove o reparo de fraturas tem uma longa história, datada de 1812. O mecanismo pelo qual estimulação elétrica promove a osteogênese ainda é assunto de especulação científica, entretanto esse método não farmacológico, utilizado no presente trabalho, já mostrou efeitos positivos na promoção e estímulo da osteogênese. O presente trabalho objetivou analisar a influência da aplicação de campo elétrico pulsado nas características histológicas e propriedades mecânicas do tecido ósseo em osteotomias experimentais realizadas em tíbias de ratos. Foram utilizados 52 ratos com fraturas cirúrgicas unilaterais do terço médio da tíbia, sem lesão dos músculos e do periósteo. Os animais foram divididos em dois grupos: grupo controle, que não recebeu estimulação e grupo tratado com campo elétrico. Esses foram divididos em dois subgrupos: animais sacrificados no 19º pós-operatório e animais sacrificados no 27º pós-operatório. O membro fraturado foi tratado com campo elétrico pulsado com freqüência fundamental de 1,5 MHz e 200 \'mü\'s de largura de pulso, em sessões diárias de 20 minutos. Realizou-se radiografia desse membro no dia da cirurgia e do sacrifício. Após o tratamento sacrificaram-se os ratos e extraíram-se suas tíbias para a obtenção de material para a análise morfométrica e ensaio mecânico de flexão. Os ensaios biomecânicos revelaram que houve diferença significativa entre as médias dos grupos tratado 18 e 12 dias somente para a tensão, sendo esta maior para o grupo tratado 18 dias, para as demais propriedades mecânicas analisadas não houve diferença significativa. A análise morfométrica determinou que a relação entre os grupos controle 18 dias com tratado 18 dias bem como entre os grupos tratado 12 dias e tratado 18 dias das médias das áreas de osso formado apresentaram diferenças estatisticamente significantes. Esses resultados sugerem que existe um incremento na síntese de matriz orgânica no grupo tratado, não acompanhado linearmente pela síntese mineral. A diferença estatisticamente significativa nas tensões de ruptura, por outro lado, sugere que o aumento no grau de mineralização encontra-se em curso. / The concept that electrical stimulation promotes the repair of fractures has a long history, dated of 1812. The mechanism for which electrical stimulation promotes osteogenesis is still subject of scientific speculation, however that method non-pharmacological, used in the present work has already showed positive effects in the promotion and incentive of osteogenesis. The present work objectified to analyze the influence of the application of electric field pulsed in the histological characteristic and mechanical properties of the bone tissue in experimental osteotomy accomplished in tibias of rats. 52 rats were used with unilateral surgical fractures of the medium third of the tibia, without lesion of the muscles and of the periosteum. The animals were divided in two groups: group control, that didn\'t receive stimulation and treated group with electric field. These were divided in two subgroups: animals sacrificed in the 19th after operation and animals sacrificed in the 27th after operation. The fracture member was treated with electric field pulsed with fundamental frequency of 1,5 MHz and 200 \'mü\'s of pulse width, in daily sessions of 20 minutes. The x-ray of that member took place in the day of the surgery and of the sacrifice. After the treatment the rats were sacrificed and their tibias were extracted for the material obtaining for analysis morfometric and mechanical rehearsal of flexion. The mechanical rehearsals revealed that there was only significant difference among the averages of the treated groups 18 and 12 days for the tension, the treated group 18 days had a larger tension, for the other analyzed mechanical properties there was not significant difference. The averages of the moment of inertia and area went significantly larger for the treated group 18 days compared with the respective averages of the control group controls. The treated group 12 days presented averages significantly larger when compared to the properties: moment of inertia, neutral line and area with the control group 12 days. These results suggest that an increment exists in the synthesis of organic matrix in the treated group, not accompanied lineally by the mineral synthesis. The difference significant statistic in the rupture tensions, on the other hand, suggests that the increase in the mineralization degree meets in course.

This paper provides an investigation of recent empirical research from the EFL literature on the advantages and possible problems that may occur when using films in Swedish upper secondary schools to increase student interaction and oral production during English lessons. Also examined is what specific film-based teaching strategies educators can utilize to increase the level of speaking and interacting in the English classrooms for Swedish secondary-school students. The investigation shows that although a number of researchers agree on the many benefits of using films was large, some problems can also be identified. These advantages and problems are discussed in the study in light of different teaching theories, for example, Vygotsky’s zone of proximal development and the Swedish curriculum. Overall, films were found to be a valid tool to be used for teachers to increase the production of speaking and interacting in Swedish upper secondary schools.

This thesis concerns a study of the performance of an industrial low-speed high-torque hydrostatic drive system. This type of hydrostatic transmission is commonly used in continuous operation in a wide range of heavy-duty drive applications. In many applications the transmissions have to compete with e.g. electromechanical drives, such as DC or AC electric motors combined with gearboxes. In such situations, energy efficiency is a key selection criterion in that even a small increase in the efficiency of high power industrial drives would give substantial savings. Apart from efficiency, lifetime and reliability requirements are important parameters for industrial drive systems, as unplanned stops in industrial working processes can be very costly. The work presented in this thesis is primarily focused on analysing the efficiency behaviour in the transmission, both on the system level and on the component level. Attention has also been paid to lifetime issues, with special emphasis on wear occurring in a sliding contact in a radial piston hydraulic motor. In Paper A the distribution of power losses in a variable axial piston swash plate pump is investigated. The pump under study is commonly used in stationary industrial hydrostatic transmission systems. The churning losses in the pump have been estimated experimentally by measurements in a test rig. The leakage flow and the power losses in the contacts between the piston and the cylinder and between the slipper and the swash plate respectively were simulated with the help of the simulation tool CASPAR. For the pump studied, the churning losses are significant under the operating conditions typically occurring in industrial drive applications. The simulation results indicate that the leakage to the pump casing mainly originates from the gaps between the pistons and their respective cylinders and between the slippers and swash plate. The aim of Paper B is to study two sliding contacts inside a radial piston hydraulic motor and investigate their influence on the torque and power losses. Moreover, it is investigated whether and when a change in the lubrication regime can be expected in these contacts. This is accomplished by a combination of experimental and theoretical studies, with a special focus on two lubricated sliding contacts: the distributor valve contact and the piston/cam roller contact. The theoretical analysis of the contacts indicates, among other things, that the piston/cam roller contact can enter the mixed lubrication regime at low motor speeds. At low running speeds, an increased wear rate has been noted in the contact between the cylinder bore and the piston skirt in a radial piston hydraulic motor. Paper C describes a comparative investigation into different hydraulic fluids' friction properties and wear protection abilities. To simulate the contact between the cylinder bore and the piston skirt in the hydraulic motor, tests were performed in a reciprocating test rig where the contact geometry was of the cylinder-plate type. In the model test a synthetic ester aimed at meeting the conditions in water turbine applications received a top ranking regarding both friction and wear protection properties. / Godkänd; 2003; 20070217 (ysko)

We calculated the fraction of ‘clumpy’ galaxies (fclumpy) for three samples of nearby galaxies. These samples include interacting galaxies with strong tidal features, collisional ring galaxies, and normal spiral galaxies. We define a ‘clumpy’ galaxy as a galaxy that has luminous star-forming regions contributing more than 8% of the total flux for the galaxy. We calculate fclumpy for 16 different wavelengths. We find that fclumpy is highest in the ultraviolet, Hα, and 24μm, while fclumpy is the lowest in optical and near-infrared wavelengths. We also see a significant increase in fclumpy for the interacting samples compared to the normal spirals.

Increasing interest in productivity, safety and environmental issues have highlighted the area of maintenance and reliability. The increasing cost of maintenance covers both preservation and sustainable exploitation of resources and awareness in maintaining equipment in a way to ensure return on investment both in the short and long run. The information obtained from condition monitoring of existing turbine, plant, rails and pumps can provide an important basis for dimensioning of future systems and components. The main objective of this research work is to develop and apply methods for efficient condition monitoring, and hence reduce maintenance costs and provide a framework for development and implementation of computer based decision tools. Furthermore, methods enabling existing process data and cost effective transducers to be used together with modern data analysis and diagnostic tools for condition monitoring of complex mechanical systems have been examined and prototypes developed. The areas of investigation covered in this work are hydropower turbines, rails and the main cooling pumps in a nuclear power-plant. The interest in diagnostics for hydropower turbines was driven by the obvious risk of contamination of water by oil leaks and expensive refurbishments caused by wear of the Kaplan turbine vane bearings. The intrest in risk analysis was motivated by Vattenfall's intrest in gaining knowledge about the state of all turbines in the company. The aim of this project was to develop a generic model of hydropower turbine behavior using physics-based models based on material properties, load tolerances, etc.. An important question was whether it was possible to predict the wear rate and plan predictive replacement or maintenance. A systematic approach to find failure modes, their effects, their causes and consequences in combination with Fault Tree Analysis was needed. The objective of this project was to examine a systematic approach to map failure modes and their causes in an hydropower turbine. We have restricted the study to turbine units of the Kaplan, Francis and tube types. The objective of the study concerning rail track was to develop methods and equipment for detection of surface damage in rail track rail in addition to the present system of practice of visual examination. The equipment developed has to be used to obtain objective statistical data for evaluating maintenance methods and efforts. We have restricted the study to spalling and headchecks on the rail head surface and running edge. The method developed enables measurements of different types of surface damage such as spalling and shelling to be made with inductive transducers sensitive to the distance to the measured object. The assumption here is that the damage being detected is characterized by the absence of material from rail surface. The main object of condition monitoring of the cooling pumps was to be able to detect bearing wear in order to be able to plan and carry out restoration well ahead of breakdown or bearing seizure. The study was restricted to the main cooling pump motor and its main bearings. Condition monitoring of the pumps was done using a method based on current measurements. Analysis of the currents on the main cooling pump of the power plant proved that it is possible to monitor the condition of the pump in spite of the presence of electronic frequency converters which distorts the signal. / <p>Godkänd; 2002; 20070222 (ysko)</p>

This licentiate thesis deals with a hybrid experimental and numerical method, the so-called Hybrid Technique, to study film thickness and pressure distribution and to investigate the behaviour and properties of lubricants in highly loaded EHL conjunctions. The Hybrid Technique combines experimental studies and advanced numerical calculations. In the experimental part of the hybrid approach Optical interferometry and a Ball &amp; Disc system are applied to obtain the colour intensity images of the EHL contact. The images that captured by a colour video system are then subjected for image analysis to evaluate the film thickness maps from the colour interferograms. The pressure distribution is obtained numerically by solving the equation of elastic deformation. Using the Hybrid Technique the pressure and lubricant film thickness in the contact are obtained without having made any assumptions regarding rheological behaviour of the lubricant. This makes the described approach to a very useful tool in investigations of EHL conjunctions under extreme conditions or in the study of multi-phase lubricants. A detailed description of the Hybrid Technique is given. Method is tested out on oil lubricated and grease lubricated contacts. Results are presented and discussed. / <p>Godkänd; 1999; 20070403 (ysko)</p>

The objective of this licentiate thesis was to study the effect of tool wear for sheet metal forming tools and how the wear process can be simulated in an efficient manner. Three Papers are appended to this licentiate thesis. Paper A covers the influence of tool geometry in deep drawing. In paper B is the way of calculating with finite element analysis described. The wear of a steel cylinder oscillating against a steel plate was studied experimentally. The worn shape of the cylinder was then compared with a numerical simulation of the shape. Paper C shows how numerical simulations can be used to simulate wear of deep drawing tools. The wear of two different deep drawing tools has been investigated. The shape of the tools before and after wear have been compared as well as the stresses and strains in the formed cups. / Godkänd; 2000; 20070317 (ysko)