ADSORPTION OF STREPTAVIDIN ONTO POLYSTYRENE SURFACE

Microparticles of various sizes carrying different surface modifications have numerous technological and biomedical applications, for example to create a larger target for a molecular receptor by binding multiply ligands to the surface of the microparticle. The aim of the present work is to study how to most efficiently couple protein molecules to the surface of such microparticles. In the current study I have focused on the coupling of Streptavidin-Alexa Flour 488 (SA-AF 488) to polystyrene microparticles (PSMs). The passive adsorption of SA-AF 488 onto PSMs with diameter 6 µm was first investigated at two different pH. It was found that maximal adsorption occurs when pH is in the neighbourhood of SA-AF’s isoelectric point. However, the protein adsorption on the PSMs was uneven for the passive adsorption. To obtain a more even protein adsorption I then investigated covalent coupling of the same protein on carboxyl-modified PSMs (PSM-COOH) as well as amine modified PSMs (PSM-NH2) with diameter 1 µm. This approach resulted in more even protein coverage on the PSMs and of the two covalently-coupled PSMs it was found that the PSM-COOH bound more proteins in comparison to PSM-NH2. The study shows that efficiently coupling of protein molecules can be achieved to microparticles, opening up for different proteins such as antibodies to be coupled to microspheres of various sizes.Mikropartiklar är mer än 100 gånger mindre än ett hårstrå. De brukar användas som behållare för läkemedel eller för att markera enskilda molekyler. För dessa ändamål måste ytan på mikropartiklarna modifieras med olika kemiska grupper. Jag har i detta arbete undersökt olika metoder för att binda in protein till mikropartiklar. Som modellsystem valdes mikropartiklar tillverkade av plasten polystyren och testet gick ut på att undersöka hur man kan koppla proteinet Streptavidin till dessa. Jag undersökte tre olika metoder: passiv bindning till omodifierade partiklar, kovalent bindning till karboxyl-modifierade partiklar och kovalent bindning till amin-modifierade partiklar. För den passiva bindningen undersöktes hur pH inverkar på inbindningen. Bäst inbindning erhölls då pH var kring 5 vilket motsvarar det pH där proteinets nettoladdning är noll. Hög proteintäckning uppnåddes, men optisk mikroskopi kunde avslöja att denna inbindning inte var jämn utan att Streptavidin ofta band i kluster på partiklarnas yta. I kovalent bindning bands Streptavidin kemiskt till de modifierade mikropartiklarna. Olika reaktionssteg skedde beroende på om ytan var modifierad med karboxylgrupper eller amingrupper. Här fick jag också hög proteintäckning på mikropartiklarna, men till skillnad mot den passiva inbindningen var täckningen här mycket jämnare. Av de bägge teknikerna gav karboxyl-modiferade mikropartiklar bäst inbindning. Slutligen undersöktes hur dessa mikropartiklar bäst skulle förvaras för att inte klumpa ihop sig eller binda till andra molekyler. En vanligt förekommande metod för det senare är att tillsätta en molekyl för att blockera alla oönskade bindningar. Betakasein användes för detta syfte, men det upptäcktes att denna molekyl band Streptavidin och fick partiklarna att aggregera mer. Att bara förvara partiklarna i normal buffertlösning eller att använda en annan molekyl (t.ex. glycin) än betakesein fungerade därför bäst. Sammanfattningsvis så har jag undersökt olika metoder för att binda in specifika molekyler till mikropartiklar. Av dessa är den passiva inbindningen den enklaste men den sämsta, då det är svårt att få en jämn molekylinbindning . För att få ytan att bli jämnt täckt med protein, så är kemisk bindning till karboxyl-modifierade mikropartiklar det bästa alternativet

Tsunami evacuation model for Sumner, Christchurch, New Zealand

Sumner, a coastal suburb located to the south-east of Christchurch, New Zealand, is highly exposed to a number of tsunami hazards. In tsunami mitigation plans, evacuation plays a crucial role in saving human lives, especially for communities located in low-lying coastal areas. The aim of this thesis is to enhance the methodological basis for development of tsunami evacuation plans in Sumner. To achieve this, a numerical simulation output of far-field tsunami impacts in Sumner was used to establish the maximum likely inundation extent and flow depth. This, together with population census data and daily activity patterns specified for the study area, established the spatio-temporal basis for characterising population exposure to the tsunamic hazard. A geospatial evacuation analysis method (Least Cost Path Distance), augmented with variable population exposure and distributed travel speeds, was used to characterise spatial variation in evacuation times and the corresponding numbers of evacuees and vehicles. Three ‘extreme’ end-member scenarios were utilised to address possible evacuation methods; all pedestrians evacuated to 20 metres elevation, all pedestrians to bus stops for evacuation using public transport, and all people evacuated using private vehicles. This thesis has made a methodological contribution to tsunami evacuation simulation by characterising variable spatio-temporal population exposure, and incorporating terrain properties into population and vehicle movements. The methods are equally applicable to other locations, to other hazards, and for both pre- and post-disaster evacuation analyses

On the analysis of the dc dynamics of multi-terminal VSC-HVDC systems using small signal modeling

In this paper, an analysis of the dc dynamics of multiterminal VSC-HVDC systems using the small signal modeling method is presented. Usually, the VSC controllers are designed under the consideration that they operate independently of each other. However, the possible interactions among them and the dc grid should be studied, especially in multi-terminal topologies. In this paper, three VSC-HVDC systems are modeled and, after linearization, the eigenvalues of the system are calculated for different loading conditions. The results from this analysis are compared to those obtained from more detailed models using PSCAD. It is shown that the operating point, the gains of the direct-voltage controller and the cable dynamics have an impact on the system performance

Réorganisation du mouvement avec l'apprentissage d'une habileté motrice complexe, la marche athlétique (rôle de l'énergie métabolique et de la perception de l'effort. Effet de cet apprentissage sur les transitions marche-course)

Ce travail avait pour premier objectif d analyser la réorganisation du mouvement lors de l apprentissage d une habileté motrice complexe, la marche athlétique. Le deuxième objectif était de mieux comprendre le rôle des facteurs métaboliques et de la perception de l effort sur ce processus.Pour cela, les deux premières études se sont intéressées à l évolution d un grand nombre de variables cinématiques avec la pratique. Les participants ont reçu au début de chaque séance de pratique trois consignes (i.e., contraintes biomécaniques) concernant la règlementation et la technique de la marche athlétique. Les résultats de l étude 1 ont mis en évidence une évolution rapide de la coordination et du contrôle (Newell, 1985) qui semble atteindre un plateau à la quatrième séance de pratique sur les sept réalisées. L étude 2, qui analyse d une façon plus approfondie ces quatre premières séances, a indiqué un rôle important des contraintes de la tâche sur la réorganisation du mouvement avec la pratique,réfutant l existence de principes généraux concernant la maîtrise des degrés de liberté (Bernstein,1967). De plus, l étude 1 a montré une réduction des valeurs métaboliques et de la perception de l effort périphérique lors de la pratique, qui corrèlent significativement avec la réorganisation globale du mouvement. Les résultats semblent indiquer un rôle important des informations sensorielles périphériques sur l adoption de patterns de mouvements plus économiques avec la pratique. L étude 3a montré que suite aux 7 séances d apprentissage, les participants adoptent spontanément au test de transition un nouveau comportement, la marche athlétique, entre la marche et la course, et ce pour des raisons non-métaboliques. En conclusion, ce travail propose que la réorganisation du mouvement lors de l apprentissage de la marche athlétique soit orientée par les contraintes de la tâche d une part et parla perception de l effort périphérique d autre part dans un but d optimisation métabolique. Toutefois,l optimisation des facteurs métabolique ne semble pas prioritaire lorsque le système locomoteur doit s adapter rapidement face à un niveau critique de contrainte.The first aim of the present work was to investigate movement reorganization with learning a complex motor skill, racewalking. The second aim was to bring more insight into the role of metabolic factors and perceived exertion. To do so, the first two studies analyzed the evolution of a large number of kinematic variables when participants underwent the practice sessions. At the start of each session, three instructions (i.e., biomechanical constraints) concerning the regulations and technique of racewalking were given. The results of the first study put forward a rapid evolution ofcoordination and control (Newell, 1985) that seem to reach a plateau at the fourth session out of seven in total. The second study, that investigated closely these first four sessions, revealed an important role of task constraints on movement reorganization, refuting the existence of general principles concerning the mastery of degrees of freedom (Bernstein, 1967). Furthermore, the first study showed a reduction in metabolic values and peripheral perceived exertion with practice, which were significantly correlated to the global movement reorganization. Overall, the results seem to raise an important role of peripheral sensory information on the adoption of more economical movement patterns with practice. The third study showed that after the seven learning session, participants spontaneously adopted racewalking as a new pattern in the transition test, between walking and running, for non-metabolic reasons. In conclusion, the present work proposes that the movement reorganization accompanying the learning of racewalking is oriented by task constraints on one sideand peripheral perceived exertion on the other aiming for metabolic optimization. Nevertheless, optimization of metabolic factors doesn t seem a priority when the motor system should quickly adapt to a critical level of constraints.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Smart and Secure CAV Networks Empowered by AI-Enabled Blockchain: Next Frontier for Intelligent Safe-Driving Assessment

Securing safe-driving for connected and autonomous vehicles (CAVs) continues to be a widespread concern despite various sophisticated functions delivered by artificial intelligence for in-vehicle devices. Besides, diverse malicious network attacks become ubiquitous along with the worldwide implementation of the Internet of Vehicles, which exposes a range of reliability and privacy threats for managing data in CAV networks. Combined with the fact that the capability of existing CAVs in handling intensive computation tasks is limited, this implies a need for designing an efficient assessment system to guarantee autonomous driving safety without compromising data security. Motivated by this, in this article, we propose a novel framework, namely Blockchain-enabled intElligent Safe-driving assessmenT (BEST), that offers a smart and reliable approach for conducting safe driving supervision while protecting vehicular information. Specifically, a promising solution that exploits a long short-term memory model is introduced to assess the safety level of the moving CAVs. Then, we investigate how a distributed blockchain obtains adequate trustworthiness and robustness for CAV data by adopting a byzantine fault tolerance-based delegated proof-of-stake consensus mechanism. Simulation results demonstrate that our presented BEST gains better data credibility with a higher prediction accuracy for vehicular safety assessment when compared with existing schemes. Finally, we discuss several open challenges that need to be addressed in future CAV networks.Comment: 8 pages, 6 figures. This paper has been accepted for publication by IEEE Networ

Geographic Trends of Tobacco-Related Cancers in Cyprus

BACKGROUND: Causal relationships have been previously established between smoking and various cancers. In Cyprus, 39 % of men and 14 % of women reported daily smoking in 2008. The objective of this study was to compare the incidence of tobacco-related cancers to all other cancers by district and rural-urban classification to understand the impact of tobacco in Cyprus. METHODS: Data on lung, urinary bladder, oral, pharyngeal, head/neck, and laryngeal cancers were obtained from the Cyprus Cancer Registry (1998-2008). There were 3,635 patients with tobacco-related cancers and 18,780 with non-tobacco cancers. Univariate analysis comparing tobacco-related cancers and all other cancers were conducted with regards to age at diagnosis, age groups, sex, smoking status, disease stage, and rural/urban status, with a p-value of 0.05 considered significant. Smoking prevalence, lung cancer, and bladder cancer rates of Cyprus were also compared to a number of other European countries. RESULTS: Patients with tobacco-related cancers were older than those with non-tobacco cancers (mean age 67.2 ± 12.4 vs. 62.4 ± 17.1, p \u3c 0.0001). Among those with tobacco-related cancers, 80.1 % were male compared to 45.4 % males with other cancer types. The proportion of ever smokers was higher among males compared to females in urban and rural districts. Sub-districts 41 (Age Adjusted Rate (AAR) 41.9, 95 % CI: 35.7-48.1), 60 (AAR 40.3, 95 % CI: 35.2-45.3), and 50 (AAR 36.3, 95 % CI: 33.8-38.7) had the highest rates of tobacco-related cancers. The overall tobacco-related cancer rate was the highest among males in urban districts (AAR 60.8, 95 % CI: 58.2-63.5). Among tobacco-related cancers, lung cancer had the highest overall AAR (17.9 per 100,000) while head and neck cancer had the lowest overall AAR (5.3 per 100,000). Additionally, even though Cypriot males aged 65-69 years old exhibited higher smoking prevalence than other European countries, the overall lung and bladder cancer rates were lower in Cyprus. CONCLUSION: Despite the high proportion of smokers in Cyprus, cancer rates are low compared to other countries. Future in-depth measurements of relevant risk factors and smoking exposure can help understand this phenomenon and provide insights for cancer prevention

The Effects of Flooding on Shirakawa Delta Morphology

Floods can significantly alter the morphology of a delta, from inputting increased volumes of sediments to modifying the reach of incoming waves, currents, and other gravity-driven forces occurring within the near shore. Kumamoto experienced flooding in July 2012. This flood event altered the equilibrium profile of the intertidal flat area of the Shirakawa River. This research looks at these modifications and attempts to explain their long-term implications on the overall delta morphology. Data collected over a 30-year period was analyzed and profiles were generated to better analyze and assess the trend in delta morphological changes. Numerical predictions on delta morphology in the presence of gravitydriven sediment transport were applied to investigate the morphological changes related to the flood event. The slope of equilibrium profile is lower and steeper offshore, helping to explain the models created before and after the flood occurred

A critical role for Apc in hematopoietic stem and progenitor cell survival

The adenomatous polyposis coli (Apc) tumor suppressor is involved in the initiation and progression of colorectal cancer via regulation of the Wnt signaling cascade. In addition, Apc plays an important role in multiple cellular functions, including cell migration and adhesion, spindle assembly, and chromosome segregation. However, its role during adult hematopoiesis is unknown. We show that conditional inactivation of Apc in vivo dramatically increases apoptosis and enhances cell cycle entry of hematopoietic stem cells (HSCs)/ hematopoietic progenitor cells (HPCs), leading to their rapid disappearance and bone marrow failure. The defect in HSCs/HPCs caused by Apc ablation is cell autonomous. In addition, we found that loss of Apc leads to exhaustion of the myeloid progenitor pool (common myeloid progenitor, granulocyte-monocyte progenitor, and megakaryocyte-erythroid progenitor), as well as the lymphoid-primed multipotent progenitor pool. Down-regulation of the genes encoding Cdkn1a, Cdkn1b, and Mcl1 occurs after acute Apc excision in candidate HSC populations. Together, our data demonstrate that Apc is essential for HSC and HPC maintenance and survival

Becoming a nurse : a process of learning

EThOS - Electronic Theses Online ServiceGBUnited Kingdo