[pt] O problema de particionamento de grafos em cliques ocorre freqüentemente em diversas áreas tais como Ciências sociais, Ciências Econômicas, Biologia, Análise de Agrupamentos e em todas as áreas onde é necessário a classificação de elementos. Estuda-se aqui os principais algoritmos exatos e as principais heurísticas que constam na literatura. É feita uma análise do desempenho das heurísticas no pior caso e apresenta-se uma classe especial de problemas para os quais o seu desempenho é arbitrariamente ruim. Apresentam-se quatro novas heurísticas para o problema, duas delas baseadas nos métodos conhecidos por simulated anneling e por tabu search. Elas são comparadas entre si através da análise dos resultados de suas aplicações a problemas-teste, a problemas que ocorre na realidade e a classe de problemas especiais mencionada acima. / [en] The clique partitioning problem arise very often in many fields as Social Science, Economics, Biology, Cluster analysis and in all other fields that need a classification of elements. The main exact algorithms and heuristics that appear in the literature are studied. A especial class of instances of the clique partitioning problem for which the most comonly used heuristics perform arbitrarily bad is exhibited. Four new heuristics are presented and two of them are based on the known simulated anneling and tabu search methods. They are analised by their application to test-problems, real-life-problems and to the special class of instances mentioned above

Members of a guild of cursorial spiders (Pardosa spp. and Alopecosa spp.) spatially segregated among five discrete habitats, from a streamside cobble habitat grading laterally along a successional gradient to the leaf litter zone of a transition or climax riparian forest. Seasonal activity peaked in midsummer for all guild members. Spiders were active diurnally earlier in the streamside habitats, and levels of activity were positively correlated with light intensity. Guild members Pardosa tristis and Pardosa uncata were most different in habitat selection and periods of diurnal activity. Males and females of all guild species differed in their distribution among habitats and over months of collection. Measures of guild species diversity and evenness were variable between habitats, and were largely influenced by the relatively high abundance of one or two guild species, particularly in the streamside habitats.

Many problems appearing in scientific computing and other areas can be formulated as a graph partitioning problems. Examples include data distribution for parallel computers, decomposition of sparse matrices and VLSI-design. In this survey we present the graph partitioning problem, describe some applications and introduce many of the algorithms used to solve the problem.

No description available.

Thesis (PhD (Genetics))--University of Stellenbosch, 2010. / Dissertation presented for the degree of Doctor of Philosophy Stellenbosch University. / ENGLISH ABSTRACT: Phosphorus (P) is essential for the survival of all living organisms and forms part of several key biological molecules and processes. The basic biological function of all cells depends on the availability of P as structural element in phospholipids and nucleic acids. P plays a central role in the energy metabolism of the cell by activating metabolic intermediates of carbohydrate metabolism and by acting as an energy currency in the form of adenosine tri-phosphate (ATP). ATP is produced during photosynthesis from the energy derived from sunlight, probably the most important biological process on earth. The balance of P supply and demand is of critical importance here. Plants assimilate P in the form of orthophosphate (Pi) via its roots and utilises complex mechanisms to redistribute and balance the Pi concentrations throughout the plant. These processes are collectively known as phosphate homeostasis and in this study we utilised molecular techniques to study some key aspects of this complex network of mechanisms in the plant Arabidopsis thaliana. When the role of the PHT1;5 Pi transporter was investigated in photosynthesis under Pi limitation a new mechanism utilised by plants to supply Pi for the production of ATP in the chloroplast was discovered. During periods of adequate Pi supply plants make use of the triose phosphate / phosphate translocator (TPT) to exchange Pi for phosphorylated carbon intermediates. This transporter does, however, not function at the low Pi concentrations present during Pi limitation and the plant therefore express an alternative transporter i.e. PHT1;5. Together with this transporter several genes were identified that was expressed to allow the export of carbon intermediates from the chloroplast via starch turnover. Amongst these, several alternative isoforms of the enzymes responsible for starch turnover are expressed during Pi limiting conditions. It is therefore suggested that the products of starch degradation, e.g. glucose and maltose are the potential candidates for carbon export from chloroplasts under Pi limiting conditions. In an attempt to perturb the Pi concentrations in the Arabidopsis vacuole we expressed the three genes of a newly discovered polyphosphate (PolyP) polymerase from the yeast Sacharomyces cerevisiae in Arabidopsis. This enzyme complex accumulates PolyP in the yeast vacuole and since the plant vacuole is playing a key role in buffering Pi concentrations we anticipated some observable effects that could lead to the elucidation of the mechanisms involved. Production of PolyP was conclusively shown in plant callus, but it was only at very low concentrations with no detectable perturbing effect and undetectable in whole plants. With the aim to apply this technology to the PolyP and PHT1;5 lines developed in the other parts of this study, newly developed fluorescent indicator protein nanosensors (FLIPPi) were evaluated as a method for detecting and monitoring in vivo Pi concentrations in multicellular plant organs. This technique is capable of detecting changes in metabolite concentrations in real-time and it was applied to the roots of Arabidopsis seedlings subjected to Pi limitation. We specifically looked at changes in the cytosol, but our results revealed no detectable changes occurring in the Pi concentrations in this compartment. This was interpreted to indicate lower levels of Pi in this compartment as was previously expected. / AFRIKAANSE OPSOMMING: Fosfaat (P) is essensieël vir die oorlewing van alle organismes en maak deel uit van etlike kern biologiese prosesse en molekules. Die basiese biologiese funksionering van alle selle hang direk af van die beskikbaarheid van P as strukturele element van fosfolipiede en nuklëinsure. Fosfaat speel 'n sentrale rol in die energie metabolisme van 'n sel deur metaboliese intermediante te aktiveer en deur op te tree as die geld eenheid van sellulere energie in die vorm van adenosien tri-fosfaat (ATP). ATP word gegenereer gedurende fotosintese vanaf die energie wat van sonlig vasgevang word, dit is waarskeinlik die belangrikste biologiese proses op aarde. Dit is van kritiese belang dat die fosfaat vraag en aanbod hier fyn gebalanseer word. Plante assimileer P in die vorm van ortofosfaat (Pi) deur hulle wortels en maak gebruik van komplekse meganismes om Pi deur die plant te versprei en konsentrasies te balanseer. Hierdie prosesse staan gesamentlik bekend as fosfaat homeostase en in die huidige studie het ons gebruik gemaak van molekulêre tegnieke om 'n paar belangrike aspekte van hierdie komplekse netwerk van prosesse in die plant Arabidopsis thaliana te bestudeer. Toe die rol van die PHT1;5 Pi transporter in fotosintese onder toestande van Pi tekort bestudeer is, is 'n nuwe meganisme ontdek waarmee plante Pi verskaf aan chloroplaste vir die proses van fotosintese onder toestande van Pi tekort. Gedurende periodes wat die plant genoegsame Pi tot sy beskikking het, word van die triose fosfaat / fosfaat uitruiler (TPT) gebruik gemaak om Pi uit te ruil vir gefosforileerde koolstof metaboliete. Hierdie transporter kan egter nie onder die lae Pi konsentrasies wat voorkom in die sitoplasma onder Pi tekort toestande funksioneer nie, en gevolglik moet die plant van 'n alternatiewe transporter naamlik PHT1;5 uitdruk. Verskeie ander gene is ook geidentifiseer wat saam met hierdie transporter onder toestande van Pi tekort uitgedruk word en die plant toelaat om koolstof tussengangers uit die chloroplaste uit te vervoer via die proses van stysel produksie en afbraak. Onderandere is verskeie alternatiewe isoforme van die gene wat verandwoordelik is vir stysel produksie en afbraak identifiseer wat uitgedruk word onder toestande van Pi tekort. In 'n poging om die Pi konsentrasies in die Arabidopsis vakuool te versteur is drie gene van die nuut ontdekte polifosfaat (PolyP) polimerase kompleks van die gis Sacharomyces cerevisiae in Arabidopsis uitgedruk. Hierdie ensiem kompleks is verandwoordelik vir die akkumulasie van PolyP in die gis vakuool en siende die plant vakuool 'n kern rol speel in die buffering van Pi konsentrasies in die plant, het ons sekere waarneembare gevolge verwag wat kon lei tot die ontrafeling van die meganismes hierby betrokke. Die produksie van PolyP in plant kallus is duidelik gedemonstreer, maar dit was slegs teen baie lae konsentrasies met geen waarneembare versteuringseffek nie, en kon glad nie in heel plante waargeneem word nie. Met die oog daarop om hierdie tegnologie toe te pas op die bestudering van die PolyP en PHT1;5 lyne wat in die ander dele van hierdie studie ontwikkel is, is 'n nuut ontwikkelde fluoresente indikator protein nanosensor (FLIPPi) tegnologie evalueer as 'n metode om Pi konsentrasies in vivo in multisellulere plant organe waar te neem en te monitor. Hierdie tegniek is in staat daartoe om veranderinge in Pi konsentrasies in selle direk te monitor en is gevolglik op die wortels van Arabidopsis saailinge onder Pi tekort toestande toegepas. Daar is spesifiek na veranderinge in die sitosol gekyk, maar ons resultate kon geen waarneembare veranderinge in Pi konsentrasies in hierdie kompartement uitwys nie. Hierdie resultaat beteken waarkeinlik dat die Pi konsentrasies in hierdie kompartement waarskeinlik baie laer is as wat voorheen verwag is.

As modern embedded systems are becoming more sophisticated the demands on their applications significantly increase. A current trend is to utilize the advances of heterogeneous platforms (i.e. platform consisting of different computational units (e.g. CPU, FPGA or GPU)) where different parts of the application can be distributed among the different computational units as software and hardware implementations. This technology can improve the application characteristics to meet requirements (e.g. execution time, power consumption and design cost), but it leads to a new challenge in finding the best combination of hardware and software implementation (referred as system configuration). The decisions whether a part of the application should be implemented in software (e.g. as C code) or hardware (e.g. as VHDL code) affect the entire product life-cycle. This is traditionally done manually by the developers in the early stage of the design phase. However, due to the increasing complexity of the application the need of a systematic process that aids the developer when making these decisions to meet the demands rises. Prior to this work a methodology called MULTIPAR has been designed to address this problem. MULTIPAR applies component-/model-based techniques to design the application, i.e. the application is modeled as a number of interconnected components, where some of the components will be implemented as software and the remaining ones as hardware. To perform the partitioning decisions, i.e. determining for each component whether it should be implemented as software or hardware, MULTIPAR proposes a set of formulas to calculate the properties of the entire system based on the properties for each component working in isolation. This thesis aims to show to what extent the proposed system formulas are valid. In particular it focuses on validating the formulas that calculate the system response time, system power consumption, system static memory and system FPGA area. The formulas were validated trough an industrial case study, where the system properties for different system configurations were measured and calculated by applying these formulas. The measured values and calculated values for the system properties were compared by conducting a statistical analysis. The case study demonstrated that the system properties can be accurately calculated by applying the system formulas.

No description available.

The Multi-resolution Assignment and Loading of Transport Activities (MALTA) system is a simulation-based Dynamic Traffic Assignment model that exploits the advantages of multi-processor computing via the use of the Message Passing Interface (MPI) protocol. Spatially partitioned transportation networks are utilized to estimate travel time via alternate routes on mega-scale network models, while the concurrently run shortest path and assignment procedures evaluate traffic conditions and re-assign traffic in order to achieve traffic assignment goals such as User Optimal and/or System Optimal conditions.Performance gain is obtained via the spatial partitioning architecture that allows the simulation domains to distribute the work load based on a specially designed Recursive On-line Load Balance model (ROLB). The ROLB development describes how the transportation network is transformed into an ordered node network which serves as the basis for a minimum cost heuristic, solved using the shortest path, which solves a multi-objective NP Hard binary optimization problem. The approach to this problem contains a least-squares formulation that attempts to balance the computational load of each of the mSim domains as well as to minimize the inter-domain communication requirements. The model is developed from its formal formulation to the heuristic utilized to quickly solve the problem. As a component of the balancing model, a load forecasting technique is used, Fast Sim, to determine what the link loading of the future network in order to estimate average future link speeds enabling a good solution for the ROLB method.The runtime performance of the MALTA model is described in detail. It is shown how a 94% reduction in runtime was achieved with the Maricopa Association of Governments (MAG) network with the use of 33 CPUs. The runtime was reduced from over 60 minutes of runtime on one machine to less than 5 minutes on the 33 CPUs. The results also showed how the individual runtimes on each of the simulation domains could vary drastically with naïve partitioning methods as opposed to the balanced run-time using the ROLB method; confirming the need to have a load balancing technique for MALTA.

Total evapotranspiration (ET) is the key process that links the land and the atmosphere via water, energy and carbon exchange. ET is a combination of evaporation and transpiration, which behave dynamically in very different ways. In this work we investigate the relative contribution of transpiration and soil evaporation to total ET in a semi-wooded, semi-arid forest in the Manitou Research Park northwest of Colorado Springs, CO. We use stable water isotopes measured at different levels within and outside the canopy, over a 30-day period (June 26 - July 26, 2010), using a field-deployable cavity ring-down spectrometer. The traditional "Keeling plot" analysis is used to partition the ET flux from moisture that comes from outside of the ecosystem, and then a simple model is used to partition the transpiration flux. In addition, we introduce a new alternative "multi-level" method to calculate the fraction of transpiration to total ET. Both the "Keeling plot" method and the "multi-level" method yield very similar fractions of transpiration to total ET, ranging from about 15% to about 85%. We compare both methodologies and discuss some of the corrections that must be made when measuring with high-frequency field-deployable instruments.

The degradation of toxic and volatile contaminants in aqueous streams is considered a challenge using conventional bioremediation strategies. At moderate concentrations, toxic contaminants induce microbial inhibition, which results in an overall decrease of reaction rates. On the other hand, volatile compounds are often stripped out of solution into the atmosphere during aeration in conventional wastewater treatments, and are not treated. The addition of a second non-aqueous phase with affinities for the contaminants can reduce aqueous concentrations to sub-inhibitory levels and also decrease contaminant volatilization, while still allowing controlled release of contaminants back to the microbial population; such systems have been denoted as Two Phase Partitioning Bioreactor (TPPB). The current work examined and compared the performance of solid-liquid TPPB to a liquid-liquid TPPB and a single phase system. The systems were compared in the simultaneous degradation of phenol and butyl acetate, two substrates known for their relatively high levels of toxicity and volatility, respectively. The solid-liquid TPPB, using 2 polymers selected heuristically, showed an improvement of 40 and 54 % in phenol degradation rates compared to the single phase and the liquid-liquid systems. Additionally, the solid-liquid system presented a 55 and 11 % enhancement in the amount of butyl acetate degraded. At higher initial substrate concentration the solid-liquid TPPB showed an improvement in the phenol degradation rate and the amount of butyl acetate degraded of 44 and 94 % respectively, compared to the single phase system. In order to rationalize polymer screening for solid-liquid TPPBs, selection criteria based on first principles were developed, and were based on consideration of polymer accessibility and polymer-solute thermodynamic affinity. Polymer accessibility was evaluated by considering glass transition temperature (Tg) and degree of crystallinity, while polymer-solute thermodynamic affinity was assessed using three different methods, Hildebrand solubility parameters, Hansen iii Solubility Parameters (HSP) and activity coefficients at infinite dilution. It was found that the HSP method gave the best trends and its predictions had better agreement with the experimental results. Consequent biodegradation experiments with a single, rationally selected polymer, and a mixture of waste polymers, demonstrated the superior performance of rational selected polymers. / Thesis (Master, Chemical Engineering) -- Queen's University, 2013-05-02 16:24:39.655