US policy toward rogue states: Comparing the Bush administration's policy toward Iraq and North Korea

The George W. Bush administration resorted to war to respond to the threat of weapons of mass destruction in Iraq, whereas it virtually ruled out the use of force to resolve the North Korean nuclear issue. By utilizing various strands of realist international relations theories, we trace motivations behind the administration's divergent foreign-policy choices toward rogue states. That the United States rushed to war against Iraq while procrastinating on North Korea presents a puzzle to conventional realism, which postulates that great powers observe changes in relative capabilities and respond accordingly. We argue that policy differences should be embedded in discussion of the administration's foreign-policy grand strategy, which sought to sustain the hegemonic status of the United States in the world. Iraq and North Korea had different implications for Bush's grand strategy, thereby calling for different approaches. By tracing the strategic design of the Bush administration, we attempt to provide a more complete account of policy differences toward rogue states, as well as indicate the significant changes in US policy during the George W. Bush administration and since.

Scientific and Religious Mindsets: A Candid Look at the Perils of a Panglossian President

Through Voltaire’s novella Candide, this essay examines the differences between a scientific and a religious mindset and the consequences of poor decision-making when a political leader has a religious mindset that he misapplies to fundamentally scientific questions. By analyzing various decisions that President Bush has made, it is argued that he has a religious mindset that has resulted in several fallacious choices of extreme import, yielding considerable losses. As such, a decision-maker with power should be able to distinguish questions best answered with a scientific mindset from those that are in the realm of philosophy or religion and apply a scientific mindset to the former. A scientific mindset formulates a theory that yields testable propositions, it acquires data and uses that to evaluate the verity of the theory. As the data contradict the theory’s predictions, the theory is adjusted. The religious mindset proffers certain explanations but then holds steadfastly to them. It ignores contrary evidence, does not adjust its tenets, or alter its prescribed behaviors, attacks the integrity of those who espouse contrarian viewpoints, and commits logical falla- cies, such as inverting the causative relationship.

Drive cycle analysis of the performance of hybrid electric vehicles

 

The boundary lubrication of chemically grafted and cross-linked hyaluronic acid in phosphate buffered saline and lipid solutions measured by the surface forces apparatus

High molecular weight hyaluronic acid (HA) is present in articular joints and synovial fluid at high concentrations; yet despite numerous studies, the role of HA in joint lubrication is still not clear. Free HA in solution does not appear to be a good lubricant, being negatively charged and therefore repelled from most biological, including cartilage, surfaces. Recent enzymatic experiments suggested that mechanically or physically (rather than chemically) trapped HA could function as an “adaptive” or “emergency” boundary lubricant to eliminate wear damage in shearing cartilage surfaces. In this work, HA was chemically grafted to a layer of self-assembled amino-propyl-triethoxy-silane (APTES) on mica and then cross-linked. The boundary lubrication behavior of APTES and of chemically grafted and cross-linked HA in both electrolyte and lipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) solutions was tested with a surface forces apparatus (SFA). Despite the high coefficient of friction (COF) of μ ≈ 0.50, the chemically grafted HA gel significantly improved the lubrication behavior of HA, particularly the wear resistance, in comparison to free HA. Adding more DOPC lipid to the solution did not improve the lubrication of the chemically grafted and cross-linked HA layer. Damage of the underlying mica surface became visible at higher loads (pressure >2 MPa) after prolonged sliding times. It has generally been assumed that damage caused by or during sliding, also known as “abrasive friction”, which is the main biomedical/clinical/morphological manifestation of arthritis, is due to a high friction force and, therefore, a large COF, and that to prevent surface damage or wear (abrasion) one should therefore aim to reduce the COF, which has been the traditional focus of basic research in biolubrication, particularly in cartilage and joint lubrication. Here we combine our results with previous ones on grafted and cross-linked HA on lipid bilayers, and lubricin-mediated lubrication, and conclude that for cartilage surfaces, a high COF can be associated with good wear protection, while a low COF can have poor wear resistance. Both of these properties depend on how the lubricating molecules are attached to and organized at the surfaces, as well as the structure and mechanical, viscoelastic, elastic, and physical properties of the surfaces, but the two phenomena are not directly or simply related. We also conclude that to provide both the low COF and good wear protection of joints under physiological conditions, some or all of the four major components of joints—HA, lubricin, lipids, and the cartilage fibrils—must act synergistically in ways (physisorbed, chemisorbed, grafted and/or cross-linked) that are still to be determined.

Effect of surface roughness and electrostatic surface potentials on forces between dissimilar surfaces in aqueous solution

The first surface force measurements under electrochemical potential control between a metal and a ceramic surface across a liquid medium (water) are reported. Our experiments also investigate and reveal how increasing levels of surface roughness and dissimilarity between the potentials of the interacting surfaces influence the strength and range of electric double layer, van der Waals, hydration, and steric forces and how this contributes to deviations from DLVO theory at small distances within aqueous solution.

Force amplification response of actin filaments under confined compression

Actin protein is a major component of the cell cytoskeleton, and its ability to respond to external forces and generate propulsive forces through the polymerization of filaments is central to many cellular processes. The mechanisms governing actin's abilities are still not fully understood because of the difficulty in observing these processes at a molecular level. Here, we describe a technique for studying actin–surface interactions by using a surface forces apparatus that is able to directly visualize and quantify the collective forces generated when layers of noninterconnected, end-tethered actin filaments are confined between 2 (mica) surfaces. We also identify a force-response mechanism in which filaments not only stiffen under compression, which increases the bending modulus, but more importantly generates opposing forces that are larger than the compressive force. This elastic stiffening mechanism appears to require the presence of confining surfaces, enabling actin filaments to both sense and respond to compressive forces without additional mediating proteins, providing insight into the potential role compressive forces play in many actin and other motor protein-based phenomena.

Molecular aspects of boundary lubrication by human lubricin : effect of disulfide bonds and enzymatic digestion

Lubricin (LUB) is a glycoprotein of the synovial cavity of human articular joints, where it serves as an antiadhesive, boundary lubricant, and regulating factor for the cartilage surface. It has been proposed that these properties are related to the presence of a long, extended, heavily glycosylated and highly hydrated mucinous domain in the central part of the LUB molecule. In this work, we show that LUB has a contour length of 220 ± 30 nm and a persistence length of ≤10 nm. LUB molecules aggregate in oligomers where the protein extremities are linked by disulfide bonds. We have studied the effect of proteolytic digestion by chymotrypsin and removal of the disulfide bonds, both of which mainly affect the N− and C− terminals of the protein, on the adsorption, normal forces, friction (lubrication) forces, and wear of LUB layers adsorbed on smooth, negatively charged mica surfaces, where the protein naturally forms lubricating polymer brush-like layers. After in situ digestion, the surface coverage was drastically reduced, the normal forces were altered, and both the coefficient of friction and the wear were dramatically increased (the COF increased to μ = 1.1−1.9), indicating that the mucinous domain was removed from the surface. Removal of disulfide bonds did not change the surface coverage or the overall features of the normal forces; however, we find an increase in the friction coefficient from μ = 0.02−0.04 to μ = 0.13−1.17 in the pressure regime below 6 atm, which we attribute to a higher affinity of the protein terminals for the surface. The necessary condition for LUB to be a good lubricant is that the protein be adsorbed to the surface via its terminals, leaving the central mucin domain free to form a low-friction, surface-protecting layer. Our results suggest that this “end-anchoring” has to be strong enough to impart the layer a sufficient resistance to shear, but without excessively restricting the conformational freedom of the adsorbed proteins.

Adsorption, lubrication, and wear of lubricin on model surfaces : polymer brush-like behavior of a glycoprotein

Using a surface force apparatus, we have measured the normal and friction forces between layers of the human glycoprotein lubricin, the major boundary lubricant in articular joints, adsorbed from buffered saline solution on various hydrophilic and hydrophobic surfaces: i), negatively charged mica, ii), positively charged poly-lysine and aminothiol, and iii), hydrophobic alkanethiol monolayers. On all these surfaces lubricin forms dense adsorbed layers of thickness 60–100 nm. The normal force between two surfaces is always repulsive and resembles the steric entropic force measured between layers of end-grafted polymer brushes. This is the microscopic mechanism behind the antiadhesive properties showed by lubricin in clinical tests. For pressures up to ∼6 atm, lubricin lubricates hydrophilic surfaces, in particular negatively charged mica (friction coefficient μ = 0.02–0.04), much better than hydrophobic surfaces (μ > 0.3). At higher pressures, the friction coefficient is higher (μ > 0.2) for all surfaces considered and the lubricin layers rearrange under shear. However, the glycoprotein still protects the underlying substrate from damage up to much higher pressures. These results support recent suggestions that boundary lubrication and wear protection in articular joints are due to the presence of a biological polyelectrolyte on the cartilage surfaces.