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Key Requirement (key + requirement)
Selected AbstractsNational AIDS Commissions in Africa: Performance and Emerging ChallengesDEVELOPMENT POLICY REVIEW, Issue 2 2009Erasmus Morah This article consolidates and expands on evidence on how National AIDS Commissions (NACs) in sub-Saharan Africa are measuring up to expectations that drove their rapid adoption across the continent. While their overall performance seems reasonably good, most NACs still lack adequate power and incentive structures to hold line ministries accountable, a key requirement for co-ordinating activities and mainstreaming HIV-AIDS across the public sector. Second-generation African NACs urgently need the authority and institutional stature to effectively co-ordinate the channelling of the larger funds now available through government bureaucracy. The evolution of the epidemic also imposes requirements different from those when the current NAC architecture was crafted. [source] P- and S-wave velocities of consolidated sediments from a seafloor seismic survey in the North Celtic Sea Basin, offshore IrelandGEOPHYSICAL PROSPECTING, Issue 2 2008Donna J. Shillington ABSTRACT A geophysical survey was conducted over a hydrocarbon prospect in the North Celtic Sea Basin using a small array of ocean-bottom seismographs (OBSs). The purpose of this study was to determine the ratio of compressional (P)- to shear (S)-wave velocity of consolidated sedimentary rocks in order to constrain possible subsurface variations in pore-fluid content. The ratio of VP and VS is known to be particularly sensitive to lithology, porosity and pore-fluid content, making it a useful parameter for evaluating hydrocarbon prospects. OBSs offer a relatively cheap and time-effective means of acquiring multi-component data compared with ocean-bottom cables. In this contribution, we demonstrate the ability of an OBS survey comprising three pairs of two OBSs spaced at 1.6 km to recover lateral variations in the VP/VS ratio. A key requirement of this type of study is that S waves will be generated by mode conversions in the subsurface, since they cannot be generated in nor travel through fluids. In this survey, the contrast in physical properties of the hard seabed of the North Celtic Sea Basin provided a means of generating converted S waves. Two-dimensional ray-tracing and forward modelling was used to create both VP and VS models along a profile crossing the Blackrock prospect in the North Celtic Sea Basin. These models comprise four layers and extend to a maximum depth of 1.1 km. The observed northward decrease in the VP/VS ratio at depths of 500,1000 m below the seafloor in the study area is interpreted to represent lateral variation in the amount of gas present in the pore space of Upper Cretaceous chalks and shales overlying the prospective reservoir. [source] A multi-agent-based negotiation support system for distributed transmission cost allocationINTELLIGENT SYSTEMS IN ACCOUNTING, FINANCE & MANAGEMENT, Issue 3 2001Yonghe Yan We have developed a multi-agent system (MAS), based on the network flow model and KQML, called MASCAN, to support negotiations in the cost allocation of network transmission. This is very important to industries that have different entities connected with lines or pipes, such as the Internet and telecommunications. Such an approach is especially useful to the utility industries, such as electricity and gas, and the transportation industry. In the system, each agent represents a node in a network, for example supplier or consumer. Agents do not receive any centralized controls or information from centralized sources to guarantee autonomy,a key requirement for the agent. In this all decisions are made locally based on the rules or knowledge that each agent has or captured to communicate or coordinate with other agents for the cheapest path under fair-play requirements. We also assume that each agent is rational, that is, one of the goals or objectives of agent decisions or movements is to minimize costs or increase profits. The solution to cost allocation is to search for the equilibrium point of a non-cooperative game subject to the given constraints, for example network capacity. We applied MASCAN to model and support the negotiation of cost allocation in power transmission, and the results and how this approach supported the process of negotiation are perceived to be closer to the real-world negotiation and the outcomes were accepted more easily by the participants. Copyright © 2001 John Wiley & Sons, Ltd. [source] Numerical modeling of seismic triggering, evolution, and deposition of rapid landslides: Application to Higashi,Takezawa (2004)INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 4 2010Nikos Gerolymos Abstract A mathematical model is developed for the dynamic analysis of earthquake-triggered rapid landslides, considering two mechanically coupled systems: (a) the accelerating deformable body of the slide and (b) the rapidly deforming shear band at the base of the slide. The main body of the slide is considered as a one-phase mixture of Newtonian incompressible fluids and Coulomb solids sliding on a plane of variable inclination. The evolution of the landslide is modeled via a depth-integrated model of the Savage,Hutter type coupled with: (a) a cyclic hysteretic constitutive model of the Bouc,Wen type and (b) Voellmy's rheology for the deformation of the material within the shear band. The original shallow-water equations that govern the landslide motion are appropriately reformulated to account for inertial forces due to seismic loading, and to allow for a smooth transition between the active and the passive state. The capability of the developed model is tested against the Higashi,Takezawa landslide. Triggered by the 2004 Niigata-ken Chuetsu earthquake, the slide produced about 100m displacement of a large wedge from an originally rather mild slope. The mechanism of material softening inside the shear band responsible for the surprisingly large run-out of the landslide is described by a set of equations for grain crushing-induced pore-water pressures. The back-analysis reveals interesting patterns on the flow dynamics, and the numerical results compare well with field observations. It is shown that the mechanism of material softening is a crucial factor for the initiation and evolution of the landslide, while viscoplastic frictional resistance is a key requirement for successfully reproducing the field data. Copyright © 2009 John Wiley & Sons, Ltd. [source] Cell therapies: realizing the potential of this new dimension to medical therapeuticsJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 6 2008Pawanbir Singh Abstract Stem cells promise to treat conditions poorly served by conventional therapeutics. Cells from both embryonic and somatic tissues are being used to create cell therapies for genetic, traumatic and degenerative conditions. The current human, healthcare and fiscal costs of these conditions are significant. This review summarizes the use of stem cells for neurological and cardiac disorders and diabetes to determine the requirements for generic translational research to assist such therapies to be a reality. While there are multiple strategies in each disease area, with no clear favourite, there are clear opportunities in treatments that use a single cell type. A key requirement is to work with pluripotent progenitor cells to cultivate and differentiate a sufficiently large population of functioning cells. Challenges also arise in determining and achieving timely delivery of the correct dose of cells to where they can most effectively treat the disease and best benefit individual patients. Copyright © 2008 John Wiley & Sons, Ltd. [source] The age, metallicity and ,-element abundance of Galactic globular clusters from single stellar population modelsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007Jon T. Mendel ABSTRACT Establishing the reliability with which stellar population parameters can be measured is vital to extragalactic astronomy. Galactic globular clusters (GCs) provide an excellent medium in which to test the consistency of single stellar population (SSP) models as they should be our best analogue to a homogeneous (single) stellar population. Here we present age, metallicity and ,-element abundance measurements for 48 Galactic GCs as determined from integrated spectra using Lick indices and SSP models from Thomas, Maraston & Korn, Lee & Worthey and Vazdekis et al. By comparing our new measurements to independent determinations we are able to assess the ability of these SSPs to derive consistent results , a key requirement before application to heterogeneous stellar populations like galaxies. We find that metallicity determinations are extremely robust, showing good agreement for all models examined here, including a range of enhancement methods. Ages and ,-element abundances are accurate for a subset of our models, with the caveat that the range of these parameters in Galactic GCs is limited. We are able to show that the application of published Lick index response functions to models with fixed abundance ratios allows us to measure reasonable ,-element abundances from a variety of models. We also examine the age,metallicity and [,/Fe],metallicity relations predicted by SSP models, and characterize the possible effects of varied model horizontal branch morphology on our overall results. [source] The Wildlife Picture Index: monitoring top trophic levelsANIMAL CONSERVATION, Issue 4 2010T. G. O'Brien Abstract Although recent biodiversity loss has been compared with cataclysmic mass extinctions, we still possess few indicators that can assess the extent or location of biodiversity loss on a global scale. The Convention on Biological Diversity (CBD) has mandated development of indicators that can meet the needs of monitoring biodiversity by 2010. To date, many indicators rely on unwarranted assumptions, secondary data, expert opinion and retrospective time series. We present a new biodiversity indicator, the Wildlife Picture Index (WPI) that targets medium and large-sized terrestrial birds and mammals in forested and savannah ecosystems that. The WPI is a composite indicator based on the geometric mean of relative occupancy estimates derived from camera trap sampling at a landscape scale. It has been designed to meet the needs of a CBD indicator while avoiding many of the pitfalls that characterize some CBD indicators. We present an example using 8 years of camera trap data from Bukit Barisan Selatan National Park, Indonesia to show that the WPI is capable of detecting changes in the rate of loss of biodiversity, a key requirement of a CBD indicator. We conclude that the WPI should be effective at monitoring top trophic levels in forest and savannah ecosystems using primary data and can fill the gap in knowledge about trends in tropical biodiversity. [source] IP-driven access-independent resource management in converged access networksBELL LABS TECHNICAL JOURNAL, Issue 2 2007Markus Bauer A key requirement on future networks is to provide the user with seamless broadband access for triple-play services via any available access technology with high end-to-end quality of service. In this paper we propose a novel resource management concept on the network layer that utilizes service- and user-specific cross-layer metrics to control the resources in an all-Internet Protocol (IP) access network optimally via IP mechanisms such as routing and traffic engineering. We interpret any link, wireless or wireline, as an IP-hop in an all-IP network where major lower layer information is included in such metrics. This approach turns out to be access technology,independent, leading to a unified resource management concept in a "converged" wireline/wireless environment. With this proposal, we leverage flat IP-based cellular architectures like the Alcatel-Lucent Base Station Router (BSR) technologies and show how wireless and wireline access nodes can be integrated into future converged all-IP networks. The paper is based on results from ScaleNet, a European research initiative that is dedicated to advancing a vision of a scalable and flexible next-generation access network that provides an IP-optimized integration of heterogeneous access systems for future broadband multimedia services. © 2007 Alcatel-Lucent. [source] 293 cell cycle synchronisation adenovirus vector productionBIOTECHNOLOGY PROGRESS, Issue 1 2009Tiago B. Ferreira Abstract As the market requirements for adenovirus vectors (AdV) increase, the maximisation of the virus titer per culture volume per unit time is a key requirement. However, despite the fact that 293 cells can grow up to 8 × 106 cell/mL in simple batch mode operations, for optimal AdV infection a maximum cell density of 1 × 106 cell/mL at infection time has usually been utilized due to the so called "cell density effect". In addition, AdV titer appears to be dependent upon cell cycle phase at the time of infection. To evaluate the dependence of AdV production upon cell cycle phase, 293 cells were chemically synchronised at each phase of the cell cycle; a 2.6-fold increase on AdV cell specific titer was obtained when the percentage of cells at the S phase of the cell cycle was increased from 36 to 47%; a mathematical equation was used to relate AdV cell specific productivities with cell synchronisation at the S phase using this data. To avoid the use of chemical inhibitors, a temperature shift strategy was also used for synchronisation at the S phase. S phase synchronisation was obtained by decreasing the culture temperature to 31°C during 67 h and restoring it to 37°C during 72 h. By using this strategy we were able to synchronise 57% of the population in the S phase of the cell cycle obtaining an increase of 7.3-fold on AdV cell specific titer after infection. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Reaction of Cytidine Nucleotides with Cyanoacetylene: Support for the Intermediacy of Nucleoside-2,,3,-cyclic Phosphates in the Prebiotic Synthesis of RNACHEMBIOCHEM, Issue 6 2006Michael A. Crowe Abstract A robust and prebiotically plausible synthesis of RNA is a key requirement of the "RNA World" hypothesis, but, to date, no such synthesis has been demonstrated. Monomer synthesis strategies involving attachment of preformed nucleobases to sugars have failed, and, even if activated 5,-nucleotides could be made, the hydrolysis of these intermediates in water makes their efficient oligomerisation appear unlikely. We recently reported a synthesis of cytidine-2,,3,-cyclic phosphate 1 (C>p) in which the nucleobase was assembled in stages on a sugar-phosphate template. However, 2,,3,-cyclic nucleotides (N>p's) also undergo hydrolysis, in this case giving a mixture of the 2,- and 3,-monophosphates. This hydrolysis has previously been seen as making the, otherwise promising, oligomerisation of N>p's seem as unlikely as that of the 5,-activated nucleotides. We now find that cyanoacetylene, the reagent used for the second stage of nucleobase assembly in the synthesis of C>p, also reverses the effect of the hydrolysis by driving efficient cyclisation of C2,p and C3,p back to C>p. Excess cyanoacetylene also derivatises the nucleobase, but this modification is reversible at neutral pH. These findings significantly strengthen the case for N>p's in a prebiotic synthesis of RNA. [source] The Role of Chemistry in the Energy ChallengeCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 2 2010Robert Schlögl Prof. Chemistry with its key targets of providing materials and processes for conversion of matter is at the center stage of the energy challenge. Most energy conversion systems work on (bio)chemical energy carriers and require for their use suitable process and material solutions. The enormous scale of their application demands optimization beyond the incremental improvement of empirical discoveries. Knowledge-based systematic approaches are mandatory to arrive at scalable and sustainable solutions. Chemistry for energy, "ENERCHEM" contributes in many ways already today to the use of fossil energy carriers. Optimization of these processes exemplified by catalysis for fuels and chemicals production or by solid-state lightning can contribute in the near future substantially to the dual challenge of energy use and climate protection being in fact two sides of the same challenge. The paper focuses on the even greater role that ENERCHEM will have to play in the era of renewable energy systems where the storage of solar energy in chemical carries and batteries is a key requirement. A multidisciplinary and diversified approach is suggested to arrive at a stable and sustainable system of energy conversion processes. The timescales for transformation of the present energy scenario will be decades and the resources will be of global economic dimensions. ENERCHEM will have to provide the reliable basis for such technologies based on deep functional understanding. [source] Controlled Synthesis of Cobalt Flowerlike Architectures by a Facile Hydrothermal RouteEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2008Ya-jing Zhang Abstract Cobalt flowerlike architectures composed of hexagonal nanoplatelets have been synthesized by a simple hydrothermal reduction method. The architectures are fabricated by the reaction of CoCl2 with NaOH at 140,180 °C in the presence of sodium dodecyl benzenesulfonate (SDBS), with NaH2PO2·H2O as reducing agent. The diameters of the flowers range from 8 to 10 ,m, and the average thickness of the hexagonal sheets is about 100 nm. Higher reaction temperatures and the proper concentration of sodium hydroxide (NaOH) are key requirements for the fabrication of the flowerlike architectures. A growth mechanism for these architectures is proposed on the basis of the characterization by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The magnetic hysteresis loops at 5 K and 295 K of the cobalt flowerlike architectures show ferromagnetic characteristics with coercivities of 371 Oe and 197 Oe, respectively. Our work may shed light on the designed fabrication of complex 3D architectures of other materials.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Novel Sulfonamide Derivatives as Inhibitors of Histone DeacetylaseHELVETICA CHIMICA ACTA, Issue 7 2005Inhibition of the enzyme histone deacetylase (HDAC) is emerging as a novel approach to the treatment of cancer. A series of novel sulfonamide derivatives were synthesized and evaluated for their ability to inhibit human HDAC. Compounds were identified which are potent enzyme inhibitors, with IC50 values in the low nanomolar range against enzyme obtained from HeLa cell extracts, and with antiproliferative effects in cell culture. Extensive characterization of the structure,activity relationships of this series identified key requirements for activity. These include the direction of the sulfonamide bond and substitution patterns on the central phenyl ring. The alkyl spacer between the aromatic head group and the sulfonamide functionality also influenced the HDAC inhibitory activity. One of these compounds, m11.1, also designated PXD101, has entered clinical trials for solid tumors and haematological malignancies. [source] In vivo diffusion tensor imaging of the human optic nerve: Pilot study in normal controlsMAGNETIC RESONANCE IN MEDICINE, Issue 2 2006C.A.M. Wheeler-Kingshott Abstract Diffusion tensor imaging (DTI) of the optic nerve (ON) was acquired in normal controls using zonally oblique multislice (ZOOM) DTI, which excites a small field of view (FOV) using a fast sequence with a shortened EPI echo train. This combines the benefit of low sensitivity to motion (due to the single-shot acquisition used), with the additional advantage of reduced sensitivity to magnetic field susceptibility artifacts. Reducing the bright signal from the fat and cerebrospinal fluid (CSF) surrounding the nerve are key requirements for the success of the presented method. Measurements of mean diffusivity (MD) and fractional anisotropy (FA) indices were made in a coronal section of the middle portion of the optic nerve (ON) in the right (rON) and left (lON) ONs. The average values across 10 healthy volunteers were FArON = 0.64 ± 0.09 and FAlON = 0.57 ± 0.10, and MDrON = (1173 ± 227) × 10,6 mm2 s,1 and MDlON = (1266 ± 170) × 10,6 mm2 s,1. Measurements of the principal eigenvalue of the DT and its orthogonal component were also in agreement with those expected from a highly directional structural organization. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] Effect of processing technique on the dispersion of carbon nanotubes within polypropylene carbon nanotube-composites and its effect on their mechanical propertiesPOLYMER COMPOSITES, Issue 5 2010Amal M.K. Esawi Carbon nanotube-reinforced polymer composites are being investigated as promising new materials having enhanced physical and mechanical properties. With regards to mechanical behavior, the enhancements reported thus far by researchers are lower than the theoretical predictions. One of the key requirements to attaining enhanced behavior is a uniform dispersion of the nanotubes within the polymer matrix. Although solvent mixing has been used extensively, there are concerns that any remaining solvent within the composite may degrade its mechanical properties. In this work, a comparison is carried out between solvent and "solvent-free" dry mixing for dispersing multiwall carbon nanotubes in polypropylene before further melt mixing by extrusion. Various weight fractions of carbon nanotubes (CNTs) are added to the polymer and their effect on the mechanical properties of the resulting composites is investigated. Enhancements in yield strength, hardness, and Young's modulus when compared with the neat polymer, processed under similar conditions, are observed. Differences in mechanical properties and strain as a function of the processing technique (solvent or dry) are also clearly noted. In addition, different trends of enhancement of mechanical properties for the solvent and dry-mixed extrudates are observed. Dry mixing produces composites with the highest yield strength, hardness, and modulus at 0.5 wt% CNT, whereas solvent mixing produces the highest mechanical properties at CNT contents of 1 wt%. It is believed that this difference is primarily dependent on the dispersion of CNTs within the polymer matrix which is influenced by the processing technique. Field emission scanning electron microscopy analysis shows the presence of clusters in large wt% CNT samples produced by dry mixing. Samples produced by solvent mixing are found to contain homogeneously distributed CNTs at all CNT wt fractions. CNT pull-out is observed and may explain the limited enhancement in mechanical properties. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Balancing robust quantification and identification for iTRAQ: Application of UHR-ToF MSPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 11 2010Saw Yen Ow Abstract iTRAQ reagents allow the simultaneous multiplex identification and quantification of a large number of proteins. Success depends on effective peptide fragmentation in order to generate both peptide sequence ions (higher mass region, 150,2200,m/z) and reporter ions (low mass region, 113,121,m/z) for protein identification and relative quantification, respectively. After collision-induced dissociation, the key requirements to achieve a good balance between the high and low m/z ions are effective ion transmission and detection across the MS/MS mass range, since the ion transmission of the higher m/z range competes with that of the low m/z range. This study describes an analytical strategy for the implementation of iTRAQ on maXis UHR-Qq-ToF instruments, and discusses the impact of adjusting the MS/MS ion transmission parameters on the quality of the overall data sets. A technical discussion highlights a number of maXis-specific parameters, their impact of quantification and identification, and their cross-interactions. [source] | ||||||||||||||||