Shoulder-to-helmet (STH) impacts have been shown to cause approximately twenty percent of concussions in football, yet little research has investigated shoulder pad design and STH impacts. While shoulder pads are designed to protect the player wearing them, they have the potential to better protect the struck player in STH collisions. This study aimed to characterize STH impacts and identify the effect of shoulder pad stiffness on the struck head kinematics. Additional padding was added to a shoulder pad as means to reduce the overall stiffness of the system, and an unmodified shoulder pad acted as the control. Participants performed a series of impact tests with two shoulder pad variations to identify if additional padding in the shoulder pads could reduce head kinematics. Participants struck a helmeted Hybrid III dummy with a National Operating Committee on Standards for Athletic Equipment (NOCSAE) on the side, replicating a lateral STH impact. Linear and rotational kinematics of the struck head were recorded for each impact, and impact speed was derived from high-speed video. Peak kinematics were compared between shoulder pad configurations to identify differences in pad performance. Impact response corridors were developed from this study that could be used to inform future controlled laboratory test setups that replicate STH impacts. A controlled test setup would allow for future testing at higher impacts speeds to evaluate concussive level impacts. Overall, this study aimed to identify if shoulder pad design can affect the struck head kinematics in STH impacts, which would open a new avenue of player safety research and development. / Master of Science / Shoulder-to-helmet (STH) impacts have been shown to cause approximately twenty percent of concussions in football, yet little research has investigated shoulder pad design and STH impacts. While shoulder pads are designed to protect the player wearing them, they have the potential to better protect the struck player in STH collisions. This study aimed to characterize STH impacts and identify the effect of shoulder pad stiffness on the struck head kinematics. Participants performed a series of impact tests with two shoulder pad variations to identify if additional padding in the shoulder pads could reduce head kinematics. Participants struck the side of a crash test dummy head with their shoulder to replicate a STH impact. Linear and rotational kinematics were recorded for each impact, and impact speed was derived from high-speed video. Values that are used to quantify head injury were compared between shoulder pad configurations to identify differences in pad performance. This study defined impact response corridors that could be used to inform future controlled lab test setups that replicate STH impacts. A controlled test setup would allow for future testing at higher impacts speeds to evaluate concussive level impacts. Overall, this study aimed to identify if shoulder pad design can affect the struck head kinematics in STH impacts, which would open a new avenue of player safety research and development.

Measured and predicted static and dynamic characteristics are provided for a four-pad, rocker-pivot, tilting-pad journal bearing in the load-on-pad and load-between-pad orientations. The bearing has the following characteristics: 4 pads, .57 pad pivot offset, 0.6 L/D ratio, 60.33 mm (2.375in) pad axial length, 0.08255 mm (0.00325 in) radial clearance in the load-on-pad orientation, and 0.1189 mm (0.00468 in) radial clearance in the load-between-pad orientation. Tests were conducted on a floating test bearing design with unit loads ranging from 0 to 2903 kPa (421.1 psi) and speeds from 6.8 to 13.2 krpm. For all rotor speeds, hot-clearance measurements were taken to show the reduction in bearing clearance due to thermal expansion of the shaft and pads during testing. As the testing conditions get hotter, the rotor, pads, and bearing expand, decreasing radial bearing clearance. Hot-clearance measurements showed a 16-25% decrease in clearance compared to a clearance measurement at room temperature. For all test conditions, dynamic tests were performed over a range of excitation frequencies to obtain complex dynamic stiffness coefficients as a function of frequency. The direct real dynamic stiffness coefficients were then fitted with a quadratic function with respect to frequency. From the curve fit, the frequency dependence was captured by including a virtual-mass matrix [M] to produce a frequency independent [K][C][M] model. The direct dynamic stiffness coefficients for the load-on-pad orientation showed significant orthotropy, while the load-between-pad did not. The load-between-pad showed slight orthotropy as load increased. Experimental cross-coupled stiffness coefficients were measured in both load orientations, but were of the same sign and significantly less than direct stiffness coefficients. In both orientations the imaginary part of the measured dynamic stiffness increased linearly with increasing frequency, allowing for frequency independent direct damping coefficients. Rotordynamic coefficients presented were compared to predictions from two different Reynolds-based models. Both models showed the importance of taking into account pivot flexibility and different pad geometries (due to the reduction in bearing clearance during testing) in predicting rotordynamic coefficients. If either of these two inputs were incorrect, then predictions for the bearings impedance coefficients were very inaccurate. The main difference between prediction codes is that one of the codes incorporates pad flexibility in predicting the impedance coefficients for a tilting-pad journal bearing. To look at the effects that pad flexibility has on predicting the impedance coefficients, a series of predictions were created by changing the magnitude of the pad's bending stiffness. Increasing the bending stiffness used in predictions by a factor of 10 typically caused a 3-11% increase in predicted Kxx and Kyy, and a 10-24% increase in predicted Cxx and Cyy. In all cases, increasing the calculated bending stiffness from ten to a hundred times the calculated value caused slight if any change in Kxx, Kyy, Cxx, and Cyy. For a flexible pad an increase in bending stiffness can have a large effect on predictions; however, for a more rigid pad an increase in pad bending stiffness will have a much lesser effect. Results showed that the pad's structural bending stiffness can be an important factor in predicting impedance coefficients. Even though the pads tested in this thesis are extremely stiff, changes are still seen in predictions when the magnitude of the pad?s bending stiffness is increased, especially in Cxx, and Cyy. The code without pad flexibility predicted Kxx and Kyy much more accurately than the code with pad flexibility. The code with pad flexibility predicts Cxx more accurately, while the code without pad flexibility predicted Cyy more accurately. Regardless of prediction Code used, the Kxx and Kyy were over-predicted at low loads, but predicted more accurately as load increased. Cxx, and Cyy were modeled very well in the load-on-pad orientation, while slightly overpredicted in the load-between-pad orientation. For solid pads, like the ones tested here, both codes do a decent job at predicting impedance coefficients

This thesis presents the dynamic and static forced performance of a flexure-pivot tilting-pad bearing load between pad (LBP) configuration for different rotor speeds and bearing unit loadings. The bearing has the following design parameters: 4 pads with pad arc angle 72o and 50% pivot offset, pad axial length 0.0762 m (3 in), pad radial clearance 0.254 mm (0.010 in), bearing radial clearance 0.1905 mm (0.0075 in), preload 0.25 and shaft nominal diameter of 0.11684 m (4.600 in). The dynamic coefficients and the static performance parameters of the FPB have been compared with the theoretical predictions using the isothermal analysis from the rotordynamic software suite XLTRC2-XLTFPBrg. The bearing shows a small attitude angle, about 10o, which indicates small crosscoupling stiffnesses. The pad temperatures increase in the circumferential direction of rotation with speed and load. The pads maximum temperature was measured near the trailing edge. The dependency of the stiffness and damping coefficients on the excitation frequency has been studied. The frequency dependency in the dynamic coefficients was removed by introducing an added mass coefficient to the bearing model. The direct added mass coefficients were around 32 kg. The direct stiffness and damping coefficients increase with load, while increasing and decreasing with rotor speed, respectively. A small whirl frequency ratio (WFR) was found of about 0.15, and it decreases with load and increases with speed. A comparison between the dynamic stiffnesses using a Reynolds equation and the bulk-flow Navier-Stokes models with the experimental dynamic stiffnesses shows that the Reynolds model (even for laminar flows) is not adequate, and that the bulk-flow model should be used for rotordynamic coefficients prediction. The bulk-flow model in general predicts well the static performance parameters and the direct dynamic coefficients, and underpredicts the cross-coupled coefficients (overpredicts the stability).

In der vorliegenden Arbeit wurde das Pad-Protein von Legionella pneumophila mit zell- bzw. molekularbiologischen sowie immunochemischen Methoden charakterisiert. Mittels Einbau des mutierten Pad-Locus, kodiert auf dem Plasmid pCS-25, in das Genom der L. pneumophila Stämme WH88 (Serogruppen 6) bzw. WH89 (Serogruppe 10) wurden je drei Pad-negative Mutanten gewonnen. Mit Hilfe der PCR, des Southernblot bzw. ELISA wurde der korrekte Austausch der Wildtypsequenz gegen den mutierten Bereich des Proteins nachgewiesen. Die Infektionsversuche mit den Mutanten bestätigten die Vermutung, dass das Protein eine Rolle an der initialen Kontaktaufnahme von L. pneumophila in den natürlichen Wirt, A. castellanii, hat. Dabei wurden signifikant niedrigere Aufnahmeraten der Mutanten im Vergleich zu den beiden Wildtypen beobachtet. Durch Kultivierung und Infektion des Ursprungstammes L. pneumophila Corby, der pad-negativen Mutante CP7 und der Pad-komplementierten Mutante bei 25°C, 30°C bzw. 37°C wurde der Einfluss der Temperatur auf die Funktion des Proteins untersucht. Die Ergebnisse zeigten dabei einen signifikanten Anstieg der Aufnahmeraten bei Vergleich von 25°C und 30°C bzw. 25°C und 37°C. Keine Signifikanz trat zwischen 30°C und 37°C auf. Ein zweiter Aspekt dieses Versuchs war die Prüfung der Infektionsrate in Abhängigkeit von der Proteinexpression unter dem Einfluss der Wachstumsphase. Dabei wurden durch vergleichende Infektion von A. castellanii mit exponentiellen (EP) bzw. stationäre Phase-Kulturen (SP) in diesem Versuch signifikante Unterschiede zwischen dem Wildtyp Corby und der Mutante CP7 bzw. zwischen der Mutante CP7 und der Pad+-Komplementante bei den jeweils untersuchten Temperaturen beobachtet. Keine signifikanten Unterschiede waren zwischen Wildtyp und Pad-Komplementante feststellbar. Zur Speziesübergreifenden Charakterisierung des Proteins Pad wurde das Wildtyplocus-kodierende Plasmid (pCS31) in die fünf non-pneumophila Stämme L. parisiensis (H962); L. bozemanii (L99-343); L. bozemanii (Frankreich5); L. longbeachae (A46) und L. tauriniensis (Koper11) durch Elektroporation übertragen. Im anschließenden ELISA wurde die Expression des Proteins Pad in den komplementierten Transformanten nachgewiesen. Die Infektionsversuche ergaben überwiegend signifikant höhere Aufnahmeraten der Pad-komplementierten Klone im Vergleich zu den Pad-negativen Wildtypen. Die Infektionsversuche zeigen, dass Pad nicht an der intrazellulären Replikation beteiligt ist. Die Ergebnisse der Infektionsversuche wurden parallel dazu durch mikroskopische Untersuchung intrazellulärer Bakterien bestätigt. Die Vermutung, dass die Expression von Pad als infektionsbeteiligtes Protein beim Übergang in die virulente Phase induziert wird, wurde durch die Kultivierung über 6 Tage bis in die späte stationäre Phase bestätigt. Die Kulturen des L. pneumophila Stammes JR32 zeigen im ELISA mit dem Pad-spezifischen Antikörper 61-1 ab der spätexponentiellen Phase (nach 24 Stunden) eine ansteigende Extinktion. Im Gegensatz dazu wurde für die GacA (LetA)-negative Mutante JR32gac- eine gleichbleibend hohe Expression des Proteins Pad über den gesamten Versuchszeitraum gemessen, was erste Hinweise liefert, dass Pad gacA bzw. letA-reguliert ist. Ein zellschädigender Einfluss der Bakterien auf die Atmungskette der Amöbenzelle zu frühen Zeitpunkten der Infektion (5, 30, 120 min) wurde mittels des Cell Titer Blue Cell Viability Assays festgestellt. Die Infektion mit hitzeabgetöteten Legionellen ergab dabei eine Toxizität unter 10 % bei allen drei untersuchten Zeitpunkten. Nach Infektion mit EP- als auch mit SP-Kulturen des Wildtyps Corby wurde eine maximale Toxizität zwischen 30 % und 40 % (120 min) gemessen. Bei der Mutante wurde eine Toxizität von ca. 28% der SP-Kultur nach 120 min Infektion beobachtet. Für die weiterführende Charakterisierung des Pad-Proteins wurde eine Maus mit dem rekombinanten Protein immunisiert. Dabei wurden zusätzlich zum vorhandenen Antikörper 61-1 die Antikörper 83-1 und 83-2 gewonnen. Bei diesen handelt es sich um IgG-Antikörper. Die durchgeführten Tests lassen vermuten, dass es sich um, in der Reaktion von Mak 61-1, ähnliche Antikörper handelt. Zur strukturellen Analyse des Pad-Proteins wurde mit zwei unterschiedlichen Phagenbibliotheken nach möglichen Epitopen für den Pad-spezifischen Antikörper 61-1 gesucht. Dabei wurde unabhängig voneinander mit beiden Phagen-Bibliotheken ein Epitop (L2) im C-terminalen Bereich ermittelt. Das Einfügen von Zufallsmutationen ließ keine Eingrenzung des Epitops zu. Da es jedoch dem, mit Mak 61-7 im Peptidspotting von C. Steudel (2001) ermittelten, Epitop C3 entspricht, ist davon auszugehen, dass es sich tatsächlich um das zweite putative Epitop für den Antikörper handelt. Des Weiteren wurde mit beiden Phagen-Bibliotheken das Epitop (L1) lokalisiert. Eine Eingrenzung dieses Epitops mittels Einfügen von Zufallsmutanten war nicht möglich. Durch site-spezifische Mutation wurden alle Aminosäuren des Epitops C1 (STEUDEL, 2001) in der putativen Signalsequenz ausgetauscht. Bei Testung der Mutanten auf ihre Bindungsfähigkeit an den Antikörper 61-1 im ELISA konnte eine Beteiligung der Aminosäuren Leucin11, Phenylalanin15, Glycin18 und Prolin20 beobachtet werden. Die Ergebnisse bestätigen, dass Pad an frühen Phasen der Infektion von A.castellanii durch L.pneumophila beteiligt ist. Es ist zu vermuten, dass dieses Pad-Protein einen Selektionsvorteil für den am häufigsten nachweisbaren Vertreter dieser Familie darstellt.

This dissertation presents a series of studies related to the characterization and optimization of consumables during Chemical Mechanical Planarization (CMP). These studies are also evaluated with the purpose of reducing the cost of ownership as well as minimizing the potential environmental impacts. It is well known that pad-wafer contact and pad surface micro-structure have significant impacts on polishing performance. The first study in this dissertation investigates the effect of pad surface contact and topography on polishing performance during copper CMP. Two different types of diamond discs (3M A2810 disc and MMC TRD disc) are used to condition the polishing pad. Pad surface contact area and topography are analyzed using laser confocal microscopy and scanning electron microscopy (SEM) to illustrate how variations in pad surface micro-texture affect the copper removal rate and the coefficient of friction (COF). Polishing results show that the 3M A2810 disc generates significantly higher COF (16%) and removal rate (39%) than the MMC TRD disc. Pad surface analysis results show that the 3M A2810 disc and MMC TRD disc generate similar pad surface height probability density function and pad surface abruptness. On the other hand, the MMC TRD disc generates large flat near contact areas that correspond to fractured and collapsed pore walls while the 3M A2810 disc generates solid contact area and clear pore structures. The fractured and collapsed pore walls generated by the MMC TRD disc partly cover the adjacent pores, making the pad surface more lubricated during wafer polishing and resulting in a significantly lower COF and removal rate. In the next study, the individual "large" pad surface contact areas are differentiated from the "small" contact areas and their role in copper CMP is investigated. Surface topography and the structure of a typical individual large contact area are examined via laser confocal microscopy and SEM. In addition, the Young's Modulus of the pad surface material is simulated. A case study is presented to illustrate the role of the individual large contact area of IC1000 K-groove pad in copper CMP. SEM analysis shows that the individual large pad surface contact areas are induced by fractured pore walls and loosely attached pad debris. Simulation results indicate that individual large contact areas correspond to very low values of the Young's modulus (about 50 MPa). Such low values indicate that the pad material is soft and the summit underlying the individual large contact is not fully supported. As a result, individual large contact area implies low contact pressure and may contribute little to removal rate. Case study results confirm that the individual large contact area has minimal contribution to removal rate and indicate that the removal rate is mainly caused by small individual contact areas. In our case, small contact areas correspond to those smaller than 9 square microns. We believe that this methodology can be also applied for other kinds of pad, although the threshold values that may define "small" and "large" individual contact areas for different pads and processes need to be further investigated. In the third study, the effect of pad surface micro-texture in interlayer dielectric CMP is also investigated. Blanket 200-mm oxide wafers are polished and the polishing pad is conditioned under two different conditioning forces (26.7 and 44.5 N). Results show that when conditioning force is increased from 26.7 to 44.5 N, oxide removal rate increases by 65% while COF increases by only 7%. Pad surface contact area and topography are measured and analyzed to illustrate their effects on the oxide removal rate. While the two conditioning forces generate similar pad surface abruptness, pad surface contact area is significantly lower (by 71%) at the conditioning force of 44.5 N. Such dramatic decrease in pad surface contact area leads to a significant increase in local contact pressure and therefore results in a significant increase in oxide removal rate. The oxide removal rate and local contact pressure exhibits a Prestonian relationship. Besides the above studies on the effect of the pad surface micro-texture during blanket wafer polishing, the fourth study investigates how pad micro-texture affects dishing and erosion during shallow trench isolation (STI) patterned wafer polishing. Two different types of diamond discs (3M A2810 disc and MMC TRD disc) are used to condition the pad during wafer polishing. Dishing and erosion analysis for the patterned wafer polishing is performed using a surface profiler. To illustrate the effect of pad surface micro-texture on dishing and erosion, pad surface abruptness and mean pad summit curvature are analyzed using laser confocal microscopy. Polishing results show that the two discs generate similar blanket wafer removal rates, while the MMC TRD disc generate significantly higher dishing and erosion than the 3M A2810 disc during patterned wafer polishing. Results of pad surface micro-texture analysis show that the MMC TRD disc generates sharper asperities with higher mean pad summit curvature than the 3M A2810 disc, resulting in higher dishing and erosion. Another contribution of this dissertation is the development of a slurry film thickness quantification technique using ultraviolet-enhanced fluorescence. The technique is developed to measure slurry film thickness at any location of interest. In the next study of this dissertation, this new technique is applied to determine how two different slurry application/injection schemes (standard pad center area application method and novel slurry injection system) along with various polishing conditions such as sliding velocity, ring pressure and slurry flow rate affect slurry availability in the bow wave region of the polisher. For the standard pad center area application method, slurry is directly applied onto the pad center area and a large amount of fresh slurry flow directly off the pad surface without flowing to the pad-retaining ring interface due to the centrifugal forces. For the novel slurry injection system, slurry is introduced through an injector that is placed adjacent (<3 cm) to the retaining ring on the pad surface. Such a close distance between the injector and retaining ring allows most of the fresh slurry to be delivered efficiently to the leading edge of the retaining ring after it is injected onto the pad surface. Results show that the novel slurry injection system generates consistently thicker bow waves (up to 104 percent) at different sliding velocities, slurry flow rates and ring pressures, therefore providing more slurry availability for the pad-retaining ring interface and potentials for slurry consumption reduction in CMP processes. First order calculations yield estimates of slurry savings associated with the novel slurry injection system ranging between 8 and 48 percent depending on specific process conditions. In the last study of this dissertation, the effect of retaining ring slot design and polishing conditions on slurry flow dynamics at the bow wave is investigated. The ultraviolet-enhanced fluorescence technique is employed to measure the slurry film thickness at the bow wave for two retaining rings with different slot designs. Multiple sliding velocities, slurry flow rates and ring pressures are investigated. Results show that the retaining ring with the sharp angle slot design (PEEK-1) generates significantly thicker (on average 48%) slurry films at the bow wave than PEEK-2 which has a rounded angle slot design. For PEEK-1, film thickness at the bow wave increases with the increasing of flow rate and ring pressure and decreases with the increasing of sliding velocity. On the other hand, film thickness at bow wave does not change significantly for the PEEK-2 ring at different polishing conditions indicating an apparent robustness of the PEEK-2 design to various operating conditions. With retaining rings having different designs, and all else being the same, a thinner bow wave is preferred since it is indicative of a ring design that allows more slurry to flow into the pad-wafer interface. Therefore, the work underscores the importance of optimizing retaining ring slot design and polishing conditions for efficient slurry utilization.

La Polyarthrite Rhumatoïde (PR) est une maladie auto-immune chronique qui détruit les articulations. Les auto-anticorps (AAc) les plus spécifiques sont dirigés contre des protéines citrullinées (ACPA). Environ 30% des patients ont des AAc dirigés contre la protéine B-Raf. Les ACPA sont des IgG produits sans réponse lymphocytaire T (LT) détectable contre les protéines citrullinées. Les enzymes PAD, responsables de la citrullination, sont la cible d’AAc dans la PR. Les LT pourrait être dirigés contre les PAD. Les LB produiraient des IgG contre les PAD et les protéines citrullinées, du fait qu’elles soient fixées aux PAD durant leur citrullination. Pour tester ce modèle, nous avons injecté des PAD à des souris et suivi les LT et les Ac anti-PAD ainsi que les ACPA. Nous avons montré que l’immunisation par PAD induit des LT anti-PAD, des Ac anti-PAD ainsi que des Ac anti-peptides de fibrinogène citrulliné.B-Raf est une ser/thr kinase de la voie des MAPK impliquée dans l’inflammation et l’activation des LT. Les LT de patients PR ont une sur-activation de la voie des MAPK, induisant une rupture de tolérance envers les auto-antigènes. Notre hypothèse est que des mutations du gène BRAF pourraient être à l’origine des AAc anti-B-Raf. Nous avons identifié la présence d’une mutation du gène BRAF entrainant la substitution de la valine en alanine en position 600 (V600A) qui est trouvée en plus grande quantité dans les cellules du sang périphérique et les LT des patients PR. V600A n’est pas corrélée à la présence d’AAc anti-B-Raf, mais augmente l’activité kinase de B-Raf qui pourrait activer la voie des MAPK dans les LT et une rupture de tolérance envers les auto-antigènes. / Rheumatoid Arthritis (RA) is a chronic inflammatory autoimmune joint disease. RA most specific autoantibodies (AAb) recognize citrulline proteins (ACPA). 30% of patients with RA have anti-B-Raf AAb. ACPA are IgG that arise in the absence of associated T cell responses. PAD enzymes, responsible for the citrullination, are also targets of AAb in RA. We thus propose a mechanism to explain the emergence of ACPA. We hypothesize that anti-citrullinated protein immunization arises because, at first, PAD is recognized by T cells, which, in turn help the production of AAb to neighbor proteins citrullinated by PAD. To test this model, we primed mice with PAD proteins and looked for immune response to PAD and citrullinated proteins. We found that PAD immunization leads to T cell response, Ab anti-PAD as well as anti-citrullinated fibrinogen peptides Ab production. Anti-PAD immunization could induce anti-citrullinated protein immunization.B-Raf, a ser-thr kinase of the MAPK signalling pathway, is involved in inflammation and in T cell activation. An overexpression of B-Raf is observed in T cells from RA patients increasing T cell activation to autoantigens. Our hypothesis is that BRAF gene mutations could trigger a rupture of tolerance and AAb production in RA. We have identified a BRAF mutation, a valine residue at position 600 is substituted by an alanine (V600A). V600A is found more often and at greater quantities in patients with RA, noteworthy in their T cells. This mutation does not correlate with Anti-B-Raf AAb presence but this is a strong enhancer of B-Raf kinase activity. This could lead to abnormal T cells activation and explain tolerance rupture in RA.

This dissertation presents a series of studies related to the slurry mean residence time analysis and the pad-wafer contact characterization in Chemical Mechanical Planarization (CMP). The purpose of these studies is to further understand the fundamentals of CMP and to explore solutions to some of CMP's challenges. Mean residence time (MRT) is a widely used term that is mostly seen in classical chemical engineering reactor analysis. In a CMP process, the wafer-pad interface can be treated as a closed system reactor, and classical reactor theory can be applied to the slurry flow through the region. Slurry MRT represents the average time it takes for fresh incoming slurry to replace the existing slurry in the region bound between the pad and the wafer. Understanding the parameters that have an impact on MRT, and therefore removal rate, is critical to maintain tight specifications in the CMP process. In this dissertation, we proposed a novel slurry injection system (SIS) which efficiently introduced fresh slurry into the pad-wafer interface to reduce MRT. Results indicated that SIS exhibited lower slurry MRT and dispersion numbers but higher removal rates than the standard pad center slurry application by blocking the spent slurry and residual rinse water from re-entering the pad-wafer interface during polishing. Another study in this dissertation dealt with the effect of pad groove width on slurry MRT in the pad-wafer interface as well as slurry utilization efficiency (η). Three concentrically grooved pads with different groove widths were tested at different polishing pressures to experimentally determine the corresponding MRT using the residence time distribution (RTD) technique. Results showed that MRT and η increased significantly when the groove width increased from 300 to 600μm. On the other hand, when the groove width increased further to 900μm, MRT continued to increase while n remained constant. Results also indicated that MRT was reduced at a higher polishing pressure while η did not change significantly with pressure for all three pads. In the last study of this dissertation, the effect of pad surface micro-texture on removal rate during tungsten CMP was investigated. Two different conditioner discs ("Disc A" and "Disc B") were employed to generate different pad surface micro-textures during polishing. Results showed that "Disc B" generated consistently lower removal rates and coefficients of friction than "Disc A". To fundamentally elucidate the cause(s) of such differences, pad surface contact area and topography were analyzed using laser confocal microscopy. The comparison of the pad surface micro-texture analysis on pad surfaces conditioned by both discs indicated that "Disc A" generated a surface having a smaller abruptness (λ) and more solid contact area which resulted in a higher removal rate. In contrast, "Disc B" generated many large near-contact areas as a result of fractured and collapsed pore walls.

Die retrospektive Arbeit untersucht die in der Zeit von Januar 1993 bis Oktober 2002 an der Uniklinik Würzburg implantierten 294 aortodistalen Gefäßprothesen. Dabei erfolgte sowohl eine Auswertung der perioperativen Komplikationen als auch der Langzeitergebnisse. Mit Hilfe von Chi-Quadrat Tests und Kaplan-Meier Berechnungen konnte ein direkter Einfluss unterschiedlicher Faktoren auf die Ergebnisse nachgewiesen werden. In der Diskussion wurden die Ergebnisse internationalen Publikationen gegenübergestellt und mit alternativen Therapiemethoden verglichen. Zusammenfassend lässt sich die aortobifemorale Y-Prothese bei Patienten mit zufriedenstellendem Allgemeinzustand und einer proximal manifestierten pAVK angesichts eines durch andere Verfahren nicht erreichten Risiko-Nutzen Verhältnisses nach wie vor als Goldstandard empfehlen. / This retrospective work examines all 294 aortodistal grafts which were implantated by the surgical section of the university hospital Würzburg from the time of january 1993 till october 2002. Perioperative complications were as well in the centre of interest as longterm results. Chi-Quadrat-Tests and Kaplan-Meier-Statistics showed direct influence of several factors on the results. In the discussion the results were opposed to international publications and compared to alternative treatments. In conclusion the aortobifemoral graft in patients with satisfying general conditions and a proximal manifested pAOD due to the, by other methods never achieved, risk-benefit-ratio can still be adviced as the goldstandard.

Peripheral artery disease (PAD) affects 8 to 10 million Americans, and the incidence of PAD is expected to increase as the population ages. A high percentage of the PAD is undiagnosed prior to the onset of a serious cardiovascular event; therefore, the inability to screen and diagnose for PAD in the early stages could hinder efforts to decrease adverse consequences of cardiovascular disease. Individuals with PAD have a 3 to 5 times increased risk of cardiovascular disease (CVD) mortality when compared to people without PAD. Guided by the Stetler model, the purpose of this project was to evaluate the relationship between level of PAD, as measured by skin perfusion pressure, and HbA1c using secondary data obtained from charts of patients within the clinic setting. Data included patient gender, age, degree of PAD, and HbA1c. A Pearson's correlation investigated the relationship between the patients' HbA1c and level of PAD. There was a significant relationship between HbA1c and LT PAD (r = .21, p =.009). There was no relation in RT PAD (r =.01, n = 149, p = .90). There was a significant relationship between HbA1c and age (r = .34, p = .00). Ultimately, the goal of this study was to improve PAD recognition, encourage early intervention, and facilitate effective preventive methods. Critical limb ischemia might be delayed or prevented if it is identified earlier by screening methodologies. Early identification and treatment of PAD can improve the quality of life and care for individuals suffering with PAD.

Static performance and rotordynamic coefficients are provided for a rocker-pivot, tilting-pad journal bearing with 50 and 60 percent offset pads in a load-between-pad configuration. The bearing uses leading-edge-groove lubrication and has the following characteristics: 5-pads, 101.6 mm (4.0 in) nominal diameter, .0814 - .0837 mm (.0032 - .0033 in) radial bearing clearance, .25 to .27 preload, 60.325 mm (2.375 in) axial pad length. Operating conditions included loads from 0 to 3101 kPa (450 psi) and speeds from 7 to 16 krpm. Dynamic tests were conducted over a range of frequencies to obtain complex dynamic stiffness coefficients as functions of excitation frequency. For most test conditions, the direct real dynamic stiffnesses were well fitted with a quadratic function with respect to frequency. This curve fit allowed for the stiffness frequency dependency to be captured by including an added mass matrix [M] to a conventional [K][C] model, producing a frequency independent [K][C][M] model. The direct imaginary dynamic stiffness coefficients increased linearly with frequency, producing frequency independent direct damping coefficients. Compared to the 50 percent offset, the 60 percent offset configuration’s direct stiffness coefficients were larger at light unit loads. At high loads, the 50 percent offset configuration had a larger direct stiffness in the loaded direction. Negative direct added-mass coefficients were regularly obtained for both offsets, especially in the unloaded direction. Added-mass magnitudes were below 32 kg for all test cases. No appreciable difference was measured in direct damping coefficients for both pivot offset. A bulk-flow Navier-Stokes CFD code provided rotordynamic coefficient predictions. The following stiffness and damping prediction trends were observed for both 50 and 60 percent offsets. The direct stiffness coefficients were modeled well at light loads and became increasingly over-predicted with increasing unit load. Stiffness orthotropy was measured at zero and light load conditions that was not predicted. Direct damping predictions in the loaded direction increased significantly with unit load while the experimental direct damping coefficients remained constant with load. The direct damping coefficients were reasonably modeled only at the highest test speed of 16 krpm. Experimental cross-coupled stiffness coefficients were larger than predicted for both offsets, but were of the same sign and considerably smaller than the direct coefficients.