The Two Faces Of Peace Building

Excerpt Terminology, if not precisely defined, can lead to misinterpretation and misunderstanding. This has been the case in the way in which the United Nations has been using peacemaking, peacekeeping and, more recently, peacebuilding. Agenda for Peace, produced by the UN Secretary General in 1992 suffers from some ambiguity in this respect. For example, it refers to the military performing a peacemaking role. The military cannot make peace, that is the role of the diplomat or politician. All that the military can do is to allay, defuse and help to end the manifest violence so that the peacemaking process can better proceed in a stable and calm atmosphere

LDLR-Gene therapy for familial hypercholesterolaemia: Problems, progress, and perspectives

Coronary artery diseases (CAD) inflict a heavy economical and social burden on most populations and contribute significantly to their morbidity and mortality rates. Low-density lipoprotein receptor (LDLR) associated familial hypercholesterolemia (FH) is the most frequent Mendelian disorder and is a major risk factor for the development of CAD. To date there is no cure for FH. The primary goal of clinical management is to control hypercholesterolaemia in order to decrease the risk of atherosclerosis and to prevent CAD. Permanent phenotypic correction with single administration of a gene therapeutic vector is a goal still needing to be achieved. The first ex vivo clinical trial of gene therapy in FH was conducted nearly 18 years ago. Patients who had inherited LDLR gene mutations were subjected to an aggressive surgical intervention involving partial hepatectomy to obtain the patient's own hepatocytes for ex vivo gene transfer with a replication deficient LDLR-retroviral vector. After successful re-infusion of transduced cells through a catheter placed in the inferior mesenteric vein at the time of liver resection, only low-level expression of the transferred LDLR gene was observed in the five patients enrolled in the trial. In contrast, full reversal of hypercholesterolaemia was later demonstrated in in vivo preclinical studies using LDLR-adenovirus mediated gene transfer. However, the high efficiency of cell division independent gene transfer by adenovirus vectors is limited by their short-term persistence due to episomal maintenance and the cytotoxicity of these highly immunogenic viruses. Novel long-term persisting vectors derived from adeno-associated viruses and lentiviruses, are now available and investigations are underway to determine their safety and efficiency in preparation for clinical application for a variety of diseases. Several novel non-viral based therapies have also been developed recently to lower LDL-C serum levels in FH patients. This article reviews the progress made in the 18 years since the first clinical trial for gene therapy of FH, with emphasis on the development, design, performance and limitations of viral based gene transfer vectors used in studies to ameliorate the effects of LDLR deficiency

Interfacial Particle Dynamics: One and Two Step Yielding in Colloidal Glass.

The yielding behavior of silica nanoparticles partitioned at an air-aqueous interface is reported. Linear viscoelasticity of the particle-laden interface can be retrieved via a time-dependent and electrolyte-dependent superposition, and the applicability of the "soft glassy rheology" (SGR) model is confirmed. With increasing electrolyte concentration (φ(elect)) in the aqueous subphase, a nonergodic state is achieved with particle dynamics arrested first from attraction induced bonding bridges and then from the cage effect of particle jamming, manifesting in a two-step yielding process under large amplitude oscillation strain (LAOS). The Lissajous curves disclose a shear-induced in-cage particle redisplacement within oscillation cycles between the two yielding steps, exhibiting a "strain softening" transitioning to "strain stiffening" as the interparticle attraction increases. By varying φ(elect) and the particle spreading concentration, φ(SiO2), a variety of phase transitions from fluid- to gel- and glass-like can be unified to construct a state diagram mapping the yielding behaviors from one-step to two-step before finally exhibiting one-step yielding at high φ(elect) and φ(SiO2)

THE INFLUENCE OF PARTICLE CONCENTRATION ON THE FLUID PHASE OF AN AXISYMMETRIC MULTIPHASE IMPINGING JET

Particle image velocimetry (PIV) is used to determine the effect of particle concentration on the fluid phase of a solid-liquid multiphase impinging jet. Two spherical particles were considered, polystyrene of 1050 kg m-3 and glass of 2450 kg m-3, both with a diameter of 225 μm. The fluid axial and radial velocities are measured with particle volume fractions (φ) equal to 0, 1x10-4, 2x10-4 and 4x10-4.For both particle types as the concentration is increased, the level of axial velocity retained immediately prior to impingement (at 6 diameters from the pipe exit) also increases. At low particle concentrations the particles have little effect on the flow turbulence, however, at higher particle concentrations the particle effect becomes more significant, with a near doubling of the peak axial RMS velocity one diameter from the jet outlet in one case. The introduction of polystyrene particles has the effect of dampening radial and axial RMS velocities, except for at the highest concentration immediately after the jet outlet where the axial turbulence is enhanced by the particles

Dynamic Interactions between a Silica Sphere and Deformable Interfaces in Organic Solvents Studied by Atomic Force Microscopy.

Recent studies have successfully measured surface forces using atomic force microscope (AFM) and modelled surface deformations using the Stokes-Reynolds-Young-Laplace (SRYL) equations for particle-droplet, particle-bubble, droplet-droplet and bubble-bubble systems in various solutions. The current work focuses on interactions between spherical silica particles and a viscoelastic interface of water droplets in crude oil. The self-assembly of surface active natural polyaromatic molecules (NPAMs) at the oil-water interface has previously been shown to change a viscous dominant oil-water interface to an elastic dominant interface, with interfacial aging due to gradual formation of rigid interfacial networks. AFM was used to measure the interactions between a small silica sphere (D ≈ 8 µm) and a deformable water droplet (D ≈ 70 µm), which exhibits time-dependent interfacial viscoelasticity in NPAM solutions. Unlike the systems studied previously, the measured deformation shown as a repulsive force over the constant compliance could not be modelled adequately by the conventional SRYL equations which are applicable only to purely Laplacian interfaces. As the water droplet ages in NPAM solutions, a rigid "skin" forms at the oil-water interface, with the interface exhibiting increased elasticity. Over a short aging period (up to 15 min), interfacial deformation is well predicted by the SRYL model. However upon further exposure to the NPAM solution, droplet deformation is under predicted by the model. Physical properties of this mechanical barrier as a function of time were further investigated by measuring interfacial tension, dilatational rheology and interfacial "crumpling" (non-smooth interface) upon droplet volume reduction. By introducing a viscoelasticity parameter to account for interfacial stiffening, we are able to correct this discrepancy and predict droplet deformation under AFM cantilever compression using experimentally-determined elasticity. This parameter appears to be important for modelling non-Laplacian systems with significant viscoelastic contributions, such as biological cell membranes or polymer blends

An X-ray Tomography Study of Gas Retention in Nuclear Legacy Waste

The retention and release of flammable gases from corroded Magnox sludge waste at Sellafield, UK and secondary reprocessing waste at Hanford, USA has significant economic and safety implications for decommissioning various nuclear legacy buildings. Magnesium hydroxide is the primary precipitation product from the corrosion of first generation nuclear fuel in the UK, with hydrogen gas produced as a reaction by-product. Depending on the bed microstructure, wettability and shear yield stress behaviour, some consolidated sediments of these corrosion products are able to trap a substantial volume of gas, sufficient in some instances to become buoyant with respect to a water supernatant, resulting in an undesirable upward transfer of radioactive material from the consolidated bed. These phenomena are investigated using the decomposition of hydrogen peroxide to produce oxygen bubbles within magnesium hydroxide soft sediments at laboratory scale. X-ray tomography analysis showed that high strength sediments of 1112 Pa shear yield stress supported much larger bubbles up to 20 mm equivalent spherical diameter than beds in the 7-234 Pa range, which demonstrated almost identical bubble size distributions across the range. The largest retained bubbles became progressively more distorted with increased sediment strength until the lateral cracks consistent with tensile fracture became apparent in the 1112 Pa bed. These cracks significantly limited the capacity for bed swell as gas diffusion along the cracks to the container walls provided a continuous escape route. The capacity for gas retention was also substantially reduced when gas generation was not homogeneous through the bed as localised gas generation promoted the formation of low density pathways, rich with micro-bubbles, which enable gas transport through the bed