<p>The acceptance of blood contacting implants creating favorable conditions <i>in vivo</i> is decisively determined by their interaction with proteins that mediate inter cellular interactions with synthetic substrates. Adsorbed proteins can activate blood cascade systems like coagulation and complement that may result in serious blood clots, and/or immunological reactions. Poly (ethylene glycol) (PEG), heparin, and phosphoryl choline (PC) functional poly (methacrylates) are previously used polymers with known non-adhesive properties in blood contacting events.</p><p>This thesis contributes to this extensive research by introducing a novel type of biomaterial that equips biodegradable polymers with biomimetic functionalities. The phospholipid mimetic material is synthesized by combining biodegradable polymers with various functional polar end-groups consisting of zwitterionic phosphoryl choline (PC), anionic succinates, and cationic quaternary ammonium. The polymer backbone provides mechanical stability and biodegradability whilst the various head groups provide a variety of functions. The careful evaluation of the synthesis has allowed reaction conditions to be optimized leading to complete conversion at each step and subsequently high yields. Initially, poly (e-caprolactone) (PCL) was used since it provided a suitable synthetic starting point. However, the synthesis has also included poly (trimethylene carbonate) (PTMC) to provide a material that allows spontaneous surface enrichment of the polar PC group. This was achieved with an added hydrophilic environment. </p><p>Through the synthesis of multi PC functional PTMC, additional bulk organisation by the formation of zwitterionomers (PC ionomer) was achieved. Low modulus elasticity and water uptake were some of the properties of the formed material. As a result it was shown that the PC ionomer could be used for protein/drug loading and subsequent release. Furthermore, the material possessed non-adhesive properties in different biological environments.</p><p>Importantly, the result suggests that a versatile synthetic platform has been established that may provide a smorgasbord of different functional polymers, or combinations of such. This is indeed important since it was shown that the polymer in many ways dictates how the material may take advantage of an added functionality. </p><p>Such materials should be interesting for a variety of biomedical applications including the production of soft hemocompatible tissue.</p>

No description available.

The Thesis is focused on the properties of self-organized nanostructures. Atomic and electronic properties of different systems have been investigated using methods of electron diffraction, scanning tunneling microscopy and photoelectron spectroscopy. Implementation of the STM technique (including design, construction, and tuning of the UHV experimental set-up) has been done in the framework of present work. This time-consuming work is reported to greater detail in the experimental part of this Thesis. <br><br> The scientific part starts from the study of quantum-size effects in the electronic structure of a two-dimensional Ag film on the supporting substrate Ni(111). Distinct quantum well states in the sp-band of Ag were observed in photoelectron spectra. Analysis of thickness- and angle-dependent photoemission supplies novel information on the properties of the interface. For the first time the Ni(111) relative band gap was indirectly probed in the ground-state through the electronic structure of quantum well states in the adlayer. This is particularly important for Ni where valence electrons are strongly correlated. Comparison of the experiment with calculations performed in the formalism of the extended phase accumulation model gives the substrate gap which is fully consistent with the one obtained by ab-initio LDA calculations. It is, however, in controversy to the band structure of Ni measured directly by photoemission. These results lend credit to the simplest view of photoemission from Ni, assigning early observed contradictions between theory and experiments to electron correlation effects in the final state of photoemission. <br><br> Further, nanosystems of lower dimensionality have been studied. Stepped surfaces W(331) and W(551) were used as one-dimensional model systems and as templates for self-organization of Au nanoclusters. Photon energy dependent photoemission revealed a surface resonance which was never observed before on W(110) which is the base plane of the terrace microsurfaces. The dispersion E(k) of this state measured on stepped W(331) and W(551) with angle-resolved photoelectron spectroscopy is modified by a strong umklapp effect. It appears as two parabolas shifted symmetrically relative to the microsurface normal by half of the Brillouin zone of the step superlattice. The reported results are very important for understanding of the electronic properties of low-dimensional nanostructures. <br><br> It was also established that W(331) and W(551) can serve as templates for self-organization of metallic nanostructures. A combined study of electronic and atomic properties of sub-monolayer amounts of gold deposited on these templates have shown that if the substrate is slightly pre-oxidized and the temperature is elevated, then Au can alloy with the first monolayer of W. As a result, a nanostructure of uniform clusters of a surface alloy is produced all over the steps. Such clusters feature a novel sp-band in the vicinity of the Fermi level, which appears split into constant energy levels due to effects of lateral quantization. <br><br> The last and main part of this work is devoted to large-scale reconstructions on surfaces and nanostructures self-assembled on top. The two-dimensional surface carbide W(110)/C-R(15x3) has been extensively investigated. Photoemission studies of quantum size effects in the electronic structure of this reconstruction, combined with an investigation of its surface geometry, lead to an advanced structural model of the carbide overlayer. <br><br> It was discovered that W(110)/C-R(15x3) can control self-organization of adlayers into nanostructures with extremely different electronic and structural properties. Thus, it was established that at elevated temperature the R(15x3) superstructure controls the self-assembly of sub-monolayer amounts of Au into nm-wide nanostripes. Based on the results of core level photoemission, the R(15x3)-induced surface alloying which takes place between Au and W can be claimed as driving force of self-organization. The observed stripes exhibit a characteristic one-dimensional electronic structure with laterally quantized d-bands. Obviously, these are very important for applications, since dimensions of electronic devices have already stepped into the nm-range, where quantum-size phenomena must undoubtedly be considered. <br><br> Moreover, formation of perfectly uniform molecular clusters of C₆₀ was demonstrated and described in terms of the van der Waals formalism. It is the first experimental observation of two-dimensional fullerene nanoclusters with "magic numbers". Calculations of the cluster potentials using the static approach have revealed characteristic minima in the interaction energy. They are achieved for 4 and 7 molecules per cluster. The obtained "magic numbers" and the corresponding cluster structures are fully consistent with the results of the STM measurements. / Die aktuelle Doktorarbeit ist auf die Eigenschaften von selbst-organisierten Nanostrukturen fokussiert. Die strukturellen und elektronischen Eigenschaften von verschiedenen Systemen wurden mit den Methoden Elektronenbeugung, Rastertunnelmikroskopie und Photoelektronenspektroskopie untersucht. Insbesondere wurde die fuer die Rastertunnelmikroskopie in situ praeparierter Proben eingesetzte Apparatur im Rahmen dieser Arbeit konstruiert und aufgebaut. Einzelheiten hierzu sind im experimentellen Kapitel zu finden. <br><br> Der wissenschftliche Teil beginnt mit Untersuchungen von Quantentrogeffekten in der elektronischen Struktur einer Ag-Schicht auf Ni(111)-Substrat. Charakteristische Quantentrogzustaende im Ag-sp-Band wurden in Photoelektronenspektren beobachtet. Die Analyse von schichtdicken- und winkelabhaengiger Photoemission hat neue und wesentliche Informationen ueber die Eigenschaften des Ag/Ni-Systems geliefert. Insbesondere konnte zum ersten Mal eine relative Bandluecke im Ni-Substrat durch das Verhalten der Quantentrogzustaende indirekt vermessen werden. Das ist fuer Ni besonders wichtig, weil es sich bei Ni um ein stark korreliertes Elektronensystem handelt. Die Ergebnisse wurden mit Rechnungen auf der Basis des erweiterten Phasenmodelles verglichen. Der Vergleich ergibt eine Bandluecke, die sehr gut mit ab-initio-Rechnungen auf Basis der lokalen Elektronendichte-Naehrung uebereinstimmen. Dennoch widersprechen die Daten der Ni-Bandstruktur, die direkt mit Photoemission gemessen wird. Diese Kontroverse zeigt deutlich, dass der Unterschied zwischen Theorie und Experiment Korrelationeffekten im Endzustand der Photoemission zugeordnet werden kann. <br><br> Des weiteren wurden Nanosysteme von noch niedrigerer Dimensionalitaet untersucht. Gestufte Oberflaechen W(331) und W(551) wurden als eindimensionale Modellsysteme fuer die Selbstorganisation von Au-Nanoclustern benutzt. Photonenenergieabhaengige Photoemission hat eine neue Oberflaechen-resonanz aufgedeckt, die auf der Basisebene der Terrassen dieser Systeme auftritt. Die Dispersion E(k) von diesem Zustand, die mit winkelaufgeloester Photoemission vermessen wurde, zeigt deutlich die Einwirkung von Umklapp-Effekten. Diese zeigen sich als zwei Parabeln, die relativ zu der Terrassennormale symmetrisch um die Haelfte der Oberflaechen-Brillouinzone verschoben sind. Die erzielten Ergebnisse sind sehr wichtig fuer das Verstaendnis der elektronischen Eigenschaften von eindimensionalen Nanostrukturen. <br><br> Ausserdem wurde gezeigt, dass W(331) und W(551) als Vorlage fuer selbstorganisierte metallische Nanostrukturen dienen koennen. Eine kombinierte Untersuchung von strukturellen und elektronischen Eigenschaften von unter-monolagen Mengen von Au auf diesen Substraten wurde durchgefuehrt. Es hat sich gezeigt, dass Au mit dem Substrat an der Oberflaeche legieren kann, wenn die Oberflaeche ein wenig oxidiert und die Temperatur erhoert ist. Als Folge formiert sich auf den Stufen eine Nanostruktur von gleichen (aber nicht regelmaessig verteilten) Nanoclustern aus dieser Au-W Legierung. Diese Oberflaechenlegierung bildet ein neuartiges sp-Band in der Naehe der Fermi-Kante. Zudem spaltet dieser neue elektronische Zustand in konstante Energieniveaus auf. Das beobachtete Phaenomen wird als laterale Quantisierung interpretiert. <br><br> Das letzte Kapitel dieser Doktorarbeit bildet auch den Hauptteil. Es handelt von Selbstorganisierungsphaenomenen auf einer Oberflaechenrekonstruktion und den Eigenschaften von so hergestellten Nanostrukturen. Das zweidimensionale Oberflaechen-Karbid W(110)/C-R(15x3) wurde intensiv untersucht. Beobachtete Quantentrogeffekte in der Photoemission in Kombination mit den Ergebnissen der Rastertunnelmikroskopuntersuchungen fuehren zu einem verbesserten Strukturmodell fuer das Oberflaechenkarbid. <br><br> Es wurde auch gezeigt, dass W(110)/C-R(15x3) die Selbstorganisierung von Nanostrukturen mit sehr verschiedenen elektronischen und strukturellen Eigenschaften steuern kann. Es wurde gefunden, dass bei erhoehter Temperatur die R(15x3)-Ueberstruktur die Bildung von Nanostreifen aus unter-monolagiger Au Bedeckung, von denen jede 1 nm breit ist, kontrolliert. Die hergestellten Nanostreifen besitzen eine charakteristische eindimensionale elektronische Struktur mit lateral quantisierten d-Baendern. Basierend auf der Photoemission von Rumpfniveaus wird eine Kohlenstoff-induzierte Oberflaechenlegierung zwischen Au und W als Grund fuer die beobachtete Organisierung vorgeschlagen. Solche Phaenomene sind sehr wichtig fuer Anwendungen, seit die Mikroelektronik in den nm-Massstab eingetreten ist, in welchem mit Quantentrogeffekten zu rechnen ist. <br><br> Zusaetzlich wurde die Bildung von perfekt uniformen molekularen Nanoclustern von C₆₀ auf W(110)/C-R(15x3) demonstriert. Dieses Phaenomen kann im van-der-Waals Formalismus beschrieben werden. Die berichteten Ergebnisse sind eine erstmalige experimentelle Beobachtung von zweidimensionalen Fulleren-Nanoclustern mit "magischen Zahlen". Berechnungen der Clusterpotentiale in der statischen Naeherung im Girifalco-Modell zeigen Minima der Wechselwirkungsenergie fuer Cluster aus 4 und 7 C₆₀-Molekuelen. Diese "magischen Zahlen" sowie die entsprechenden Clusterkonfigurationen sind vollkommen konsistent mit den Ergebnissen des STM-Experiments.

Es ist seit einigen Jahren bekannt, dass Elektronen unter bestimmten Bedingungen in dünne Filme eingeschlossen werden können, selbst wenn diese Filme aus Metall bestehen und auf Metall-Substrat aufgebracht werden. In Photoelektronenspektren zeigen diese Filme charakteristische diskrete Energieniveaus, und es hat sich herausgestellt, dass sie zu großen, technisch nutzbaren Effekten führen können, wie der oszillatorischen magnetischen Kopplung in modernen Festplatten-Leseköpfen. <br><br> In dieser Arbeit wird untersucht, inwieweit die der Quantisierung in zweidimensionalen Filmen zu Grunde liegenden Konzepte auf niedrigere Dimensionalität übertragbar sind. Das bedeutet, dass schrittweise von zweidimensionalen Filmen auf eindimensionale Nanostrukturen übergegangen wird. Diese Nanostrukturen sind zum einen die Terrassen auf atomar gestuften Oberflächen, aber auch Atomketten, die auf diese Terrassen aufgebracht werden, bis hin zu einer vollständigen Bedeckung mit atomar dünnen Nanostreifen. Daneben werden Selbstorganisationseffekte ausgenutzt, um zu perfekt eindimensionalen Atomanordnungen auf Oberflächen zu gelangen. <br><br> Die winkelaufgelöste Photoemission ist als Untersuchungsmethode deshalb so geeignet, weil sie das Verhalten der Elektronen in diesen Nanostrukturen in Abhängigkeit von der Raumrichtung zeigt, und unterscheidet sich darin beispielsweise von der Rastertunnelmikroskopie. Damit ist es möglich, deutliche und manchmal überraschend große Effekte der eindimensionalen Quantisierung bei verschiedenen exemplarischen Systemen zum Teil erstmals nachzuweisen. Die für zweidimensionale Filme wesentliche Rolle von Bandlücken im Substrat wird für Nanostrukturen bestätigt. Hinzu kommt jedoch eine bei zweidimensionalen Filmen nicht vorhandene Ambivalenz zwischen räumlicher Einschränkung der Elektronen in den Nanostrukturen und dem Effekt eines Übergitters aus Nanostrukturen sowie zwischen Effekten des Elektronenverhaltens in der Probe und solchen des Messprozesses. Letztere sind sehr groß und können die Photoemissionsspektren dominieren. <br><br> Abschließend wird der Effekt der verminderten Dimensionalität speziell für die d-Elektronen von Mangan untersucht, die zusätzlich starken Wechselwirkungseffekten unterliegen. Auch hierbei treten überraschende Ergebnisse zu Tage. / It has been known for several years that under certain conditions electrons can be confined within thin layers even if these layers consist of metal and are supported by a metal substrate. In photoelectron spectra, these layers show characteristic discrete energy levels and it has turned out that these lead to large effects like the oscillatory magnetic coupling technically exploited in modern hard disk reading heads. <br><br> The current work asks in how far the concepts underlying quantization in two-dimensional films can be transferred to lower dimensionality. This problem is approached by a stepwise transition from two-dimensional layers to one-dimensional nanostructures. On the one hand, these nanostructures are represented by terraces on atomically stepped surfaces, on the other hand by atom chains which are deposited onto these terraces up to complete coverage by atomically thin nanostripes. Furthermore, self organization effects are used in order to arrive at perfectly one-dimensional atomic arrangements at surfaces. <br><br> Angle-resolved photoemission is particularly suited as method of investigation because is reveals the behavior of the electrons in these nanostructures in dependence of the spacial direction which distinguishes it from, e. g., scanning tunneling microscopy. With this method intense and at times surprisingly large effects of one-dimensional quantization are observed for various exemplary systems, partly for the first time. The essential role of bandgaps in the substrate known from two-dimensional systems is confirmed for nanostructures. In addition, we reveal an ambiguity without precedent in two-dimensional layers between spacial confinement of electrons on the one side and superlattice effects on the other side as well as between effects caused by the sample and by the measurement process. The latter effects are huge and can dominate the photoelectron spectra. <br><br> Finally, the effects of reduced dimensionality are studied in particular for the d electrons of manganese which are additionally affected by strong correlation effects. Surprising results are also obtained here. <br><br>----------------------------<br> Die Links zur jeweiligen Source der im Appendix beigefügten Veröffentlichungen befinden sich auf Seite 83 des Volltextes.

The acceptance of blood contacting implants creating favorable conditions in vivo is decisively determined by their interaction with proteins that mediate inter cellular interactions with synthetic substrates. Adsorbed proteins can activate blood cascade systems like coagulation and complement that may result in serious blood clots, and/or immunological reactions. Poly (ethylene glycol) (PEG), heparin, and phosphoryl choline (PC) functional poly (methacrylates) are previously used polymers with known non-adhesive properties in blood contacting events. This thesis contributes to this extensive research by introducing a novel type of biomaterial that equips biodegradable polymers with biomimetic functionalities. The phospholipid mimetic material is synthesized by combining biodegradable polymers with various functional polar end-groups consisting of zwitterionic phosphoryl choline (PC), anionic succinates, and cationic quaternary ammonium. The polymer backbone provides mechanical stability and biodegradability whilst the various head groups provide a variety of functions. The careful evaluation of the synthesis has allowed reaction conditions to be optimized leading to complete conversion at each step and subsequently high yields. Initially, poly (e-caprolactone) (PCL) was used since it provided a suitable synthetic starting point. However, the synthesis has also included poly (trimethylene carbonate) (PTMC) to provide a material that allows spontaneous surface enrichment of the polar PC group. This was achieved with an added hydrophilic environment. Through the synthesis of multi PC functional PTMC, additional bulk organisation by the formation of zwitterionomers (PC ionomer) was achieved. Low modulus elasticity and water uptake were some of the properties of the formed material. As a result it was shown that the PC ionomer could be used for protein/drug loading and subsequent release. Furthermore, the material possessed non-adhesive properties in different biological environments. Importantly, the result suggests that a versatile synthetic platform has been established that may provide a smorgasbord of different functional polymers, or combinations of such. This is indeed important since it was shown that the polymer in many ways dictates how the material may take advantage of an added functionality. Such materials should be interesting for a variety of biomedical applications including the production of soft hemocompatible tissue.

Work conditions within the public health care sector are physically and psychosocially demanding. This means that balancing work with recovery is essential for employees in order to avoid ill health and stay healthy. This thesis is based on four studies. Study I investigated the prevalence of upper extremity disorders (UED) in female dental personnel. Results showed that 81% reported UED. Consequently, interventions aimed at reducing these risks were called for. Study II investigated the health-related effects of two work-place interventions, physical exercise (PE) and reduced working hours (RWH). Health-improvements were more consistent in the PE group, suggesting that PE may be an appropriate intervention to reduce health-risks. However, there were no effects on recovery from work or fatigue, which may result from other factors, such as overcommitment (OC), that prolong or sustain stress-related activity. Study III showed that high OC was associated with poorer next-day recovery and increased fatigue. Also, OC was a more important predictor of lack of recovery and fatigue than were psychosocial work characteristics. This highlights the importance of considering perseverative cognitions in relation to recovery from work and fatigue, and has implications for interventions targeting work-related ill health. Study IV related lack of recovery and fatigue to cumulative biological risk, allostatic load (AL), and to individual biomarkers. Women with a profile characterized by fatigue, sleep difficulties and lack of short-term recovery had a 2.9 increased risk of AL. This was not shown in analyses of individual biomarkers. In sum, this thesis shows that recovery from work is an important factor in relation to women’s work-related health. Fatigue and recovery should be considered interrelated but distinct concepts and recovery should be assessed as an early risk factor for stress-related disease with early risk being investigated using AL rather than individual biomarkers.

<p>Diss. (sammanfattning) Stockholm : Handelshögskolan, 2006 [6], xiii, [1] s.: sammanfattning, s. 1-259, [5] s.: 4 uppsatser. Spikblad saknas</p>

Let K be a number field with ring of integers O_K and let G be a finite group.By a result of E. Noether, the ring of integers of a tame Galois extension of K with Galois group G is a locally free O_K[G]-module of rank 1.Thus, to any tame Galois extension L/K with Galois group G we can associate a class [O_L] in the locally free class group Cl(O_K[G]). The set of all classes in Cl(O_K[G]) which can be obtained in this way is called the set of realizable classes and is denoted by R(O_K[G]).In this dissertation we study different problems related to R(O_K[G]).The first part focuses on the following question: is R(O_K[G]) a subgroup of Cl(O_K[G])? When the group G is abelian, L. McCulloh proved that R(O_K[G]) coincides with the so-called Stickelberger subgroup St(O_K[G]) of Cl(O_K[G]). In Chapter 2, we give a detailed presentation of unpublished work by L. McCulloh that extends the definition of St(O_K[G]) to the non-abelian case and shows that R(O_K[G]) is contained in St(O_K[G]) (the opposite inclusion is still not known in the non-abelian case).Then, just using its definition and Stickelberger's classical theorem, we prove in Chapter 3 that St(O_K[G]) is trivial if K=Q and G is either cyclic of order p or dihedral of order 2p, where p is an odd prime number. This, together with McCulloh's results, allows us to have a new proof of the triviality of R(O_K[G]) in the cases just considered.The main original results are contained in the second part of this thesis. In Chapter 4, we prove that St(O_K[G]) has good functorial behavior under restriction of the base field. This has the interesting consequence that, if N/L is a tame Galois extension with Galois group G, and St(O_K[G]) is known to be trivial for some subfield K of L, then O_N is stably free as an O_K[G]-module.In the last chapter, we prove an equidistribution result for Galois module classes amongst tame Galois extensions of K with Galois group G in which a given prime p of K is totally split.

Current representation schemes for automatic text classification treat documents as syntactically unstructured collections of words (Bag-of-Words) or `concepts' (Bag-of-Concepts). Past attempts to encode syntactic structure have treated part-of-speech information as another word-like feature, but have been shown to be less effective than non-structural approaches. We propose a new representation scheme using Holographic Reduced Representations (HRRs) as a technique to encode both semantic and syntactic structure, though in very different ways. This method is unique in the literature in that it encodes the structure across all features of the document vector while preserving text semantics. Our method does not increase the dimensionality of the document vectors, allowing for efficient computation and storage. We present the results of various Support Vector Machine classification experiments that demonstrate the superiority of this method over Bag-of-Concepts representations and improvement over Bag-of-Words in certain classification contexts.

The goal of the thesis is to design the star-based mesh topology by introducing multiple pan-coordinators (hub/switches) under a multipath-fading environment and to improve the data transaction rate of a network which usually gets worst when there is a single pan-coordinator for synchronization of devices in conventional mesh topology; also reduce the hop-count as least as possible. Most of the work has been done on NS-2 network simulator; therefore the research model which has been used here is a simulation model. Altogether 3 simulations have been done. The first scenario is done on a simplest mesh network with a single coordinator and a radio propagation model which has been used is two-ray ground reflection model. The second scenario simulation is similar to the first scenario but in-order to provide multi-path signal fading and highly congested environment the propagation model which has been used this time is shadowing model. The final simulation which has been done is of multiple-star based mesh topology it also uses the similar radio propagation model which has been defined for second scenario. An intensive performance measurement of all the three simulations has been done in terms of transactions made per-second, packet drop rate along with an analysis of packet drop. An hop-count is also measured between star and mesh topology. For multiple star based mesh topology it can be assumed if multiple stars with a routing capability can be used then nodes in a network will be synchronized or re-synchronized with least number of hops in the congested network with a near-by pan-coordinator (hub/switch). One of the major applications of this topology can be automobile manufacturing industry where alot of machines are installed in a congested network and monitoring of every area is mandatory for swift production.