A Study of PCAC for the Nonperturbative Improvement of the Wilson Action

We present an exploratory study for the nonperturbative determination of the coefficient of the ${\cal O}(a)$ improvement term to the Wilson action, $c_{SW}$. Following the work by L\"{u}scher et al., we impose the PCAC relation as a nonperturbative improvement condition on $c_{SW}$, without, however, using the Schr\"{o}dinger functional in our calculation.Comment: 3 pages, LaTeX (uses espcrc2.sty), 4 postscript figures, to be published in the proceedings of Lattice'9

The non-perturbative O(a)-improved action for dynamical Wilson fermions

We compute the improvement coefficient $c_{sw}$ that multiplies the Sheikholeslami-Wohlert term as a function of the bare gauge coupling for two flavour QCD. We discuss several aspects concerning simulations with improved dynamical Wilson fermions.Comment: Latex file, 2 figures, 6 pages, talk given by K.J. at the International Symposium on Lattice Field Theory, 21-27 July 1997, Edinburgh, Scotlan

Relativistic Heavy Quarks on the Lattice

Lattice QCD should allow quantitative predictions for the heavy quark physics from first principles. Up to now, however, most approaches have based on the nonrelativistic effective theory, with which the continuum limit can not be taken in principle. In this paper we investigate feasibility of relativistic approaches to the heavy quark physics in lattice QCD. We first examine validity of the idea that the use of the anisotropic lattice could be advantageous to control the $m_Q a$ corrections. Our perturbative calculation, however, reveals that this is not true. We instead propose a new relativistic approach to handle heavy quarks on the isotropic lattice. We explain how power corrections of $m_Q a$ can be avoided and remaining uncertainties are reduced to be of order $(a\Lambda_{QCD})^2$.Comment: 39 pages, 8 figure as eps-fil

Shifting der Adhäsionsmolekülexpression auf neutrophilen Granulozyten während deren Migration durch die verschiedenen Kompartimente der Lunge im Rahmen der akuten pulmonalen Inflammation

Das ARDS ist trotz stetiger Optimierung der intensivmedizinischen Versorgung weltweit nach wie vor mit einer hohen Letalität von bis zu 46% behaftet. Der Verlauf der akuten pulmonalen Inflammation wird maßgeblich vom Ausmaß der PMN-Infiltration mitbestimmt. Die neutrophilen Granulozyten migrieren dabei mittels Adhäsionsmolekülen durch unter-schiedliche Lungenkompartimente: Aus dem Intravasalraum heften sie sich zunächst an das Endothel und durchwandern dieses. Anschließend gelangen die Neutrophilen durch das Interstitium und das Pulmonalepithel in die Alveole. Bisherige Kenntnisse zur Funktion einzelner Moleküle in der Lunge beziehen sich vor allem auf die transendotheliale Migration oder die Zellen in der Bronchiallavage als Endpunkt der Migration, lassen also keine durchgehende Verfolgung des Expressionsverlaufs zu. Zielsetzung dieser Arbeit war deshalb die differenzierte Untersuchung und Darstellung der Adhäsionsmoleküle auf den neutrophilen Granulozyten im Rahmen der vollständigen Durchwanderung der Lunge. Hierfür wurde bei Mäusen durch LPS-Inhalation eine Inflammation induziert. Mittels spezifischer Markierung in der Durchflusszytometrie konnte anschließend die Adhäsionsmolekülexpression von PMN-Populationen aus insgesamt vier verschiedenen Migrationsstadien erfasst werden: den intravasalen PMNs, endothelial adhärenten PMNs, interstitiellen PMNs und intraalveolären PMNs. Ergänzend wurden in vitro verschiedene Untersuchungen zur inflammatorischen und migratorischen Bedeutung der Adhäsionsmoleküle auf humanen Zellen durchgeführt. Es zeigten sich abhängig von Migrationsstadium und Molekül sehr variable Verläufe der Expression auf den Neutrophilen, was einen unterschiedlichen Impact der einzelnen Moleküle für die jeweiligen Migrationsschritte nahelegt. Während die Expressionen der Integrine CD11a und CD29 sowie die Expression des Selektin-Liganden CD162 und von PECAM-1 bzw. CD31 auf ihrem Weg in die Alveole abnahmen und demensprechend ihr Einfluss auf die PMN-Migration, steigerte sich die Expression von CD44 und CD172a. Letztere Adhäsionsmoleküle tragen vermutlich zur transepithelialen Migration und möglichen postmigratorischen Prozessen wie dem Patrouillieren am apikalen Alveolarepithel bei. CD47, CD54 und der leukozytäre Aktivierungsmarker CD11b waren im Interstitium maximal exprimiert, was für eine entscheidende Rolle bei der Interaktion mit Komponenten der Extrazellularmatrix und/oder bei der epithelialen basolateralen Adhäsion spricht. In vitro konnten die inflammatorische Bedeutung sowie migrationsbedingte Veränderungen der Molekülexpression auf humanen PMNs bestätigt werden. Die Daten dieser Arbeit zeigen erstmals die Adhäsionsmolekülexpression der PMNs abhängig von ihrem Migrationsstadium und liefern so den molekularen Hintergrund für das ganzheitliche Verständnis der PMN-Migration respektive die Basis für die Entwicklung und Verbesserung therapeutischer Strategien

EU accession, crimes and sports: the thematic frame of reciprocal perceptions between Western Balkan countries and EU

The paper outlines the reciprocal perceptions between the Western Balkan countries and the EU against the background of a future EU accession of the region. Based on the rationale that mass media is a crucial platform through which reciprocal perceptions are identified and reciprocal images are formed. A comparative newspaper analysis in 2009 focused on the reciprocal news coverage in two EU countries (Austria and Slovenia) and two Western Balkan countries (Bosnia and Herzegovina, Serbia) , which also identified the geographical and thematic frame of the reciprocal news coverage of both sides. The paper reveals that the attention paid towards the EU region in Bosnia and Herzegovina and Serbia is significantly higher than that paid towards the Western Balkan region in the EU countries. It also illustrates that EU-related topics are not the only thematic frame shaping the news coverage on both sides when the respective, ‘Other,’ is taken into account

In for a penny, in for a pound: methylphenidate reduces the inhibitory effect of high stakes on persistent risky choice

Methylphenidate (MPH) is a stimulant that increases extracellular levels of dopamine and noradrenaline. It can diminish risky decision-making tendencies in certain clinical populations. MPH is also used, without license, by healthy adults, but the impact on their decision-making is not well established. Previous work has found that dopamine receptor activity of healthy adults can modulate the influence of stake magnitude on decisions to persistently gamble after incurring a loss. In this study, we tested for modulation of this effect by MPH in 40 healthy human adults. In a double-blind experiment, 20 subjects received 20 mg of MPH, while 20 matched controls received a placebo. All were provided with 30 rounds of opportunities to accept an incurred loss from their assets or opt for a "double-or-nothing" gamble that would either avoid or double it. Rounds began with a variable loss that would double with every failed gamble until it was accepted, recovered, or reached a specified maximum. Probability of recovery on any gamble was low and ambiguous. Subjects receiving placebo gambled less as the magnitude of the stake was raised and as the magnitude of accumulated loss escalated over the course of the task. In contrast, subjects treated with MPH gambled at a consistent rate, well above chance, across all stakes and trials. Trait reward responsiveness also reduced the impact of high stakes. The findings suggest that elevated catecholamine activity by MPH can disrupt inhibitory influences on persistent risky choice in healthy adults

Electroassisted Filtration of Microfibrillated Cellulose: Insights Gained from Experimental and Simulation Studies

An electroassisted filtration technique has been employed to improve dewatering of a suspension of microfibrillated cellulose (MFC) produced via 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation. In addition, all-atom molecular dynamic (MD) simulations were performed to deepen the understanding of the complicated dewatering mechanism on a molecular level. Both the experimental and the simulation results implied that the dewatering rate was not only improved when electroassisted filtration was used but also found to be proportional to the strength of the electric field. A channeled dewatered structure was observed for these experiments and may have contributed to enhanced dewatering by providing high overall permeability. The MD simulations revealed that the electric field had a significant impact on the fibril movement, whereas the impact of pressure was limited. The simulations also suggested that the increased filtrate flow upon the application of an electric field was not only due to electroosmotic flow but also due to electrophoretic movement of the fibrils toward the anode that led to the release of water that had been trapped between the fibrils, allowing it to be pressed out together with the rest of the bulk water. This study shows that electroassisted filtration has the potential to improve the dewatering of TEMPO-MFC, and the MD simulations provide further insights into the dewatering mechanism

Capillary forces exerted by a water bridge on cellulose nanocrystals: the effect of an external electric field

Capillary forces play an important role during the dewatering and drying of nanocellulosic materials. Traditional moisture removal techniques, such as heating, have been proved to be deterimental to the properties of these materials and hence, there is a need to develop novel dewatering techniques without affecting the desired properties of materials. It is, therefore, important to explore novel methods for dewatering these high-added-value materials without negatively influencing their properties. In this context, we explore the effect of electric field on the capillary forces developed by a liquid-water bridge between two cellulosic surfaces, which may be formed during the water removal process following its displacement from the interfibrillar spaces. All-atom molecular dynamics (MD) simulations have been used to study the influence of an externally applied electric field on the capillary force exerted by a water bridge. Our results suggest that the equilibrium contact angle of water and the capillary force exerted by the water bridge between two nanocellulosic surfaces depend on the magnitude and direction of the externally applied electric fields. Hence, an external electric field can be applied to manipulate the capillary forces between two particles. The close agreement between the capillary forces measured through MD simulations and those calculated through classical equations indicates that, within the range of the electric field applied in this study, Young-Laplace equations can be safely employed to predict the capillary forces between two particles. The present study provides insights into the use of electric fields for drying of nanocellulosic materials

Surface modification effects on nanocellulose - molecular dynamics simulations using umbrella sampling and computational alchemy

Topochemical modification of nanocellulose particles, in particular acetylation, is commonly used to reduce hygroscopicity and improve their dispersibility in non-polar polymers. Despite enormous experimental efforts on cellulose surface modification, there is currently no comprehensive model which considers both (a) the specific interactions between nanocellulose particles and the surrounding liquid or polymer matrix, and (b) the interactions between the particles themselves. The second mechanism is therefore frequently ignored. The present approach is based on atomistic molecular dynamics (MD) simulations, where computational alchemy is used to calculate the changes in interactions between nanocellulose and the surrounding medium (liquid or polymer) upon modification. This is combined with another method, based on potential of mean force, to calculate interactions between particles. Results show that both contributions are of equal importance for nanoparticle surface acetylation effects. The proposed method is not restricted to either cellulose or acetylation, and has the prospect to find application in a broad context of nanomaterials design