War Signals: A Theory of Trade, Trust and Conflict

We construct a dynamic theory of civil conflict hinging on inter-ethnic trust and trade. The model economy is inhabitated by two ethnic groups. Inter-ethnic trade requires imperfectly observed bilateral investments and one group has to form beliefs on the average propensity to trade of the other group. Since conflict disrupts trade, the onset of a conflict signals that the aggressor has a low propensity to trade. Agents observe the history of conflicts and update their beliefs over time, transmitting them to the next generation. The theory bears a set of testable predictions. First, war is a stochastic process whose frequency depends on the state of endogenous beliefs. Second, the probability of future conflicts increases after each conflict episode. Third, "accidental" conflicts that do not reflect economic fundamentals can lead to a permanent breakdown of trust, plunging a society into a vicious cycle of recurrent conflicts (a war trap). The incidence of conflict can be reduced by policies abating cultural barriers, fostering inter-ethnic trade and human capital, and shifting beliefs. Coercive peace policies such as peacekeeping forces or externally imposed regime changes have instead no persistent effects.

Taajuusmuuttajien suorituskyvyn automaattinen testausympäristö

Tämä insinöörityö tehtiin ABB Oy, Drivesin Product AC -tulosyksikön tuotekehitysosastolle Helsingissä. Työssä kehitettiin taajuusmuuttajien suorituskyvyn automaattinen testausympäristö. ABB:n taajuusmuuttajien suorituskykytestejä ei ole aikaisemmin automatisoitu. Testit on tehty käsin ja niiden suorittamiseen ja tulosten käsittelyyn on kulunut paljon aikaa. Automaattisella testauksella pyrittiin testien suorittamiseen ja tulosten käsittelyyn kuluvan ajan huomattavaan pienentymiseen. Työssä ei ollut tarkoituksena tehdä suorituskykytestejä vaan kehittää automaattinen testausympäristö eli suorituskykytestipenkki, jossa suorituskykytestit on mahdollista suorittaa. Työssä keskityttiin taajuusmuuttajan nopeus- ja momenttisäätäjien suorituskykyyn. Työ toteutettiin suunnittelu- ja ohjelmointityönä. Testausympäristön laitteisto perustuu ABB:n tuotekehityslaboratorioiden olemassaoleviin testipaikkoihin. Testausympäristössä käytetään taajuusmuuttajien lisäksi pääasiassa kolmivaiheisia oikosulkumoottoreita. Lisäksi laitteistoon kuuluu ACS800-sarjan taajuusmuuttaja kuormakäyttönä, momenttianturi ja takometri eli kierrosnopeusmittari. Ohjelmointi tehtiin National Instrumentsin LabVIEW-ohjelmointiympäristön versiolla 8.0. Testausympäristön käyttöliittymänä toimii saman yrityksen TestStand-testausohjelmiston versio 3.5. Testattavien taajuusmuuttajien ohjausta ja momenttianturin lukemista varten ohjelmoitiin virtuaali-instrumentteja. Virtuaali-instrumentteja kutsutaan TestStand-testisekvensseistä. Testisekvenssit luodaan TestStandin sekvenssieditorilla ja suoritetaan sekvenssieditorissa tai operaattorin käyttöliittymässä. Työn tuloksena syntyi taajuusmuuttajien suorituskyvyn automaattinen testausympäristö. Testausympäristöä voidaan hyödyntää sekä nykyisen että seuraavan sukupolven taajuusmuuttajien testauksessa. Sillä on mahdollista suorittaa yleisimmät taajuusmuuttajien suorituskykytestit, kuten nopeus- ja momenttisäätöjen staattinen ja dynaaminen tarkkuus, hyvin kattavasti. Testit voidaan automaattisesti suorittaa koko testikäytön sallimalla pyörimisnopeus- ja kuormitusalueella. Näytteenottotaajuus voi olla enintään 1 kHz luettaessa pyörimisnopeutta ACS800-sarjan taajuusmuuttajan kautta ja momenttianturia samanaikaisesti. Virtuaali-instrumenteista koostuvia testisekvenssejä voidaan vapaasti muokata ja kehittää testejä edelleen tai luoda kokonaan uusia testejä. Testausympäristö perustuu teollisuudessa yleisesti käytettyihin ohjelmistoihin ja tarjoaa hyvät mahdollisuudet jatkokehitykselle.

Partitioning of reproduction in mother-daughter versus sibling associations : a test of optimal skew theory

A critical feature of cooperative animal societies is the reproductive skew, a shorthand term for the degree to which a dominant individual monopolizes overall reproduction in the group. Our theoretical analysis of the evolutionarily stable skew in matrifilial (i.e., mother-daughter) societies, in which relatednesses to offspring are asymmetrical, predicts that reproductive skews in such societies should tend to be greater than those of semisocial societies (i.e., societies composed of individuals of the same generation, such as siblings), in which relatednesses to offspring are symmetrical. Quantitative data on reproductive skews in semisocial and matrifilial associations within the same species for 17 eusocial Hymenoptera support this prediction. Likewise, a survey of reproductive partitioning within 20 vertebrate societies demonstrates that complete reproductive monopoly is more likely to occur in matrifilial than in semisocial societies, also as predicted by the optimal skew model.

PCR-RAPD and PCR-RFLP polymorphisms detected in Anopheles cruzii (Diptera, Culicidae)

The aim of the present study was to examine genetic variability in populations of An. cruzii by employing PCR-RAPD and PCR-RFLP markers. All analyses were carried out using individuals of the F1 generation of wild caught females obtained in Santa Catarina State (Florianópolis and São Francisco do Sul), Paraná State (Morretes, Paranaguá and Guaratuba) and São Paulo State (Cananéia). In the PCR-RAPD experiments, seven primers were used for comparisons within and among populations. The restriction profile of the ITS2 including a fragment of both 5.8S and 28S regions of the rDNA was obtained with the enzymes BstUI, HaeIII, TaqI, HhaI, Sau96I, HinfI, HincII and NruI. The PCR-RAPD method detected a large number of polymorphic bands. Genetic distance among populations of An. cruzii varied from 0,0214 to 0,0673, suggesting that all individuals used in the analyses belong to a single species. The number of migrants per generation (Nm) was 4.3, showing the existence of gene flow among populations. The restriction profile of the ITS2, 5.8S and 28S gene regions was similar in all An. cruzii samples, whereas the results obtained by using HhaI and NruI are indicative that the individuals analyzed have nucleotide sequences distinct from those of An. cruzii samples from Peruíbe and Juquiazinho deposited in GenBank.

Rearing method of Oryzaephilus surinamensis (L.) (Coleoptera, Silvanidae) on various wheat grain granulometry

Oryzaephilus surinamensis is one of most common insect pest of grains and a variety of stored products, and has been found in high numbers in almost all storage facilities. However, laboratory mass rearing of this insect for bioassays is not a simple task, mainly because of its feeding behavior, small size, and high mobility. Thus, the aim of this work was to develop a simple and efficient laboratory rearing method for O. surinamensis, using wheat kernels milled into different granulometry to obtain large number and standardized population at different life stages for bioassays. The adults were collected from storage grain facilities in the southern region of Brazil and 100 specimens were placed inside glass jars with wheat kernels milled at different grades and kept at 25±0.5ºC and 65±5% relative humidity. The insects were allowed to copulate and lay eggs for 10 days and then removed. The number of eggs, larvae, and pupae was counted at five-day intervals; longevity of the second generation adults was evaluated. The kernels milled at grade 20 were the best medium for offspring production: 89% of eggs by the 5th day; 30.5% larvae by the 10th day; 43% pupae by the 30th day and 63.4% adults at the 46th day. The adults survived up to 450 days. Culturing O. surinamensis under the described conditions, transferring the parental adults by the 10th day after infestation and replacing the media when population builds up will produce enough insects of each stage for various laboratory bioassays.

3D seismic facies characterization and geological patterns recognition (Australian North West Shelf)

EXECUTIVE SUMMARY This PhD research, funded by the Swiss Sciences Foundation, is principally devoted to enhance the recognition, the visualisation and the characterization of geobodies through innovative 3D seismic approaches. A series of case studies from the Australian North West Shelf ensures the development of reproducible integrated 3D workflows and gives new insight into local and regional stratigraphic as well as structural issues. This project was initiated in year 2000 at the Geology and Palaeontology Institute of the University of Lausanne (Switzerland). Several collaborations ensured the improvement of technical approaches as well as the assessment of geological models. - Investigations into the Timor Sea structural style were carried out at the Tectonics Special Research Centre of the University of Western Australia and in collaboration with Woodside Energy in Perth. - Seismic analysis and attributes classification approach were initiated with Schlumberger Oilfield Australia in Perth; assessments and enhancements of the integrated seismic approaches benefited from collaborations with scientists from Schlumberger Stavanger Research (Norway). Adapting and refining from "linear" exploration techniques, a conceptual "helical" 3D seismic approach has been developed. In order to investigate specific geological issues this approach, integrating seismic attributes and visualisation tools, has been refined and adjusted leading to the development of two specific workflows: - A stratigraphic workflow focused on the recognition of geobodies and the characterization of depositional systems. Additionally, it can support the modelling of the subsidence and incidentally the constraint of the hydrocarbon maturity of a given area. - A structural workflow used to quickly and accurately define major and secondary fault systems. The integration of the 3D structural interpretation results ensures the analysis of the fault networks kinematics which can affect hydrocarbon trapping mechanisms. The application of these integrated workflows brings new insight into two complex settings on the Australian North West Shelf and ensures the definition of astonishing stratigraphic and structural outcomes. The stratigraphic workflow ensures the 3D characterization of the Late Palaeozoic glacial depositional system on the Mermaid Nose (Dampier Subbasin, Northern Carnarvon Basin) that presents similarities with the glacial facies along the Neotethys margin up to Oman (chapter 3.1). A subsidence model reveals the Phanerozoic geodynamic evolution of this area (chapter 3.2) and emphasizes two distinct mode of regional extension for the Palaeozoic (Neotethys opening) and Mesozoic (abyssal plains opening). The structural workflow is used for the definition of the structural evolution of the Laminaria High area (Bonaparte Basin). Following a regional structural characterization of the Timor Sea (chapter 4.1), a thorough analysis of the Mesozoic fault architecture reveals a local rotation of the stress field and the development of reverse structures (flower structures) in extensional setting, that form potential hydrocarbon traps (chapter 4.2). The definition of the complex Neogene structural architecture associated with the fault kinematic analysis and a plate flexure model (chapter 4.3) suggest that the Miocene to Pleistocene reactivation phases recorded at the Laminaria High most probably result from the oblique normal reactivation of the underlying Mesozoic fault planes. This episode is associated with the deformation of the subducting Australian plate. Based on these results three papers were published in international journals and two additional publications will be submitted. Additionally this research led to several communications in international conferences. Although the different workflows presented in this research have been primarily developed and used for the analysis of specific stratigraphic and structural geobodies on the Australian North West Shelf, similar integrated 3D seismic approaches will have applications to hydrocarbon exploration and production phases; for instance increasing the recognition of potential source rocks, secondary migration pathways, additional traps or reservoir breaching mechanisms. The new elements brought by this research further highlight that 3D seismic data contains a tremendous amount of hidden geological information waiting to be revealed and that will undoubtedly bring new insight into depositional systems, structural evolution and geohistory of the areas reputed being explored and constrained and other yet to be constrained. The further development of 3D texture attributes highlighting specific features of the seismic signal, the integration of quantitative analysis for stratigraphic and structural processes, the automation of the interpretation workflow as well as the formal definition of "seismo-morphologic" characteristics of a wide range of geobodies from various environments would represent challenging examples of continuation of this present research. The 21st century will most probably represent a transition period between fossil and other alternative energies. The next generation of seismic interpreters prospecting for hydrocarbon will undoubtedly face new challenges mostly due to the shortage of obvious and easy targets. They will probably have to keep on integrating techniques and geological processes in order to further capitalise the seismic data for new potentials definition. Imagination and creativity will most certainly be among the most important quality required from such geoscientists.

Macroeconomic modeling for monetary policy evaluation

We describe some of the main features of the recent vintage macroeconomic models used for monetary policy evaluation. We point to some of the key differences with respect to the earlier generation ofmacro models, and highlight the insights for policy that these new frameworks have to offer. Our discussion emphasizes two key aspects of the new models: the significant role of expectations of future policy actions in the monetary transmission mechanism, and the importance for the central bank of tracking of the flexible price equilibrium values of the natural levels of output and the real interest rate. We argue that both features have important implications for the conduct of monetary policy.

Identification and Characterization of Natural Anti-Breast Cancer Compound: Costunolide

Breast cancer is the most common cancer among women, 23% (1.3 million) of the total of new cases and the second leading cause of cancer death in women exceeded only by lung cancer. Natural medicines have been proven to be a central source of narrative agents with a pharmaceutical potential. Costunolide is sesquiterpene lactones consisting of diverse plant chemicals that exhibit anti cancer action through cytotoxic effects on various cancer cells. The objectives of present study were to explore the effects of natural compounds on the proliferation of MCF-7 cells and to determine the role of ROS in natural compounds-induced apoptosis in breast cancer cells with a therapeutic potential. Results showed that costunolide screened, possess potent anticancer properties against breast cancer MCF-7 cells, Costunolide was observed as strong anti-proliferative agent with IC50 = 50µM. The anti-proliferative effect of costunolide on MCF cells was confirmed by live/dead assay using fluorescent probes calcein AV/PI. The results demonstrated that treatment of cells with costunolide decreased the viability of MCF-7 cells in a dose-dependent manner. To determine the costunolide-induced apoptosis, flow cytometric analysis was carried out. The results showed that costunolide induced apoptosis in a dose-dependent manner in breast cancer MCF-7cells. ROS are well known mediators of intracellular signaling of cascades. The excessive generation of ROS can induce oxidative stress, loss of cell functioning, and apoptosis. In the present study, we assumed that costunolide might arouse ROS level, which could be involved in induction of apoptosis. Therefore, the intracellular ROS level was measured using the ROS-detecting fluorescence dye 2, 7-dichlorofluorescein diacetate (DCF-DA). Interestingly these effects were significantly abrogated when the cells were pretreated with N-acetyl- cysteine (NAC), a specific ROS inhibitor. Costunolide induces apoptosis through extrinsic pathway in MCF-7 breast cancer cells, In order to examine whether costunolide suppresses cell growth inducing apoptotic cell death, we analyzed DNA contents and apoptosis-related proteins expression level by flow cytometry and western blot, respectively in MCF-7 breast cancer cells we investigated whether costunolide activates extrinsic apoptotic pathway. We examined the expression levels of death receptor signaling-related proteins, caspase-3, and PARP. The results showed that procaspase-3 was cleaved to yield 17 and 20kDa fragments and activation of PARP in treated cells with 25 and 50μM of costunolide. Costunolide induce apoptosis through intrinsic mitochondria pathway in MCF-7 breast cancer Cells. We examined the expression levels of mitochondrial apoptotic pathway related proteins such as anti-apoptotic protein, B-cell lymphoma protein-2 (Bcl2), and pro-apoptotic protein Bax. Costunolide involved in the down regulation of Bcl-2 and up regulation of Bax. These results suggest that costunolide may have beneficial effects for the reduction of breast cancer growth, and new therapeutic strategy for the treatment of human cancers.

A dynamic analysis of human welfare in a warming planet

Climate science indicates that climate stabilization requires low GHG emissions. Is thisconsistent with nondecreasing human welfare?Our welfare or utility index emphasizes education, knowledge, and the environment. Weconstruct and calibrate a multigenerational model with intertemporal links provided by education,physical capital, knowledge and the environment.We reject discounted utilitarianism and adopt, first, the Pure Sustainability Optimization (orIntergenerational Maximin) criterion, and, second, the Sustainable Growth Optimization criterion,that maximizes the utility of the first generation subject to a given future rate of growth. We applythese criteria to our calibrated model via a novel algorithm inspired by the turnpike property.The computed paths yield levels of utility higher than the level at reference year 2000 for allgenerations. They require the doubling of the fraction of labor resources devoted to the creation ofknowledge relative to the reference level, whereas the fractions of labor allocated to consumptionand leisure are similar to the reference ones. On the other hand, higher growth rates requiresubstantial increases in the fraction of labor devoted to education, together with moderate increasesin the fractions of labor devoted to knowledge and the investment in physical capital.

Evolutionary dynamics of coding and non-coding transcriptomes.

Gene expression changes may underlie much of phenotypic evolution. The development of high-throughput RNA sequencing protocols has opened the door to unprecedented large-scale and cross-species transcriptome comparisons by allowing accurate and sensitive assessments of transcript sequences and expression levels. Here, we review the initial wave of the new generation of comparative transcriptomic studies in mammals and vertebrate outgroup species in the context of earlier work. Together with various large-scale genomic and epigenomic data, these studies have unveiled commonalities and differences in the dynamics of gene expression evolution for various types of coding and non-coding genes across mammalian lineages, organs, developmental stages, chromosomes and sexes. They have also provided intriguing new clues to the regulatory basis and phenotypic implications of evolutionary gene expression changes.

Modular support for developing mobile ad hoc applications

Abstract This PhD thesis addresses the issue of alleviating the burden of developing ad hoc applications. Such applications have the particularity of running on mobile devices, communicating in a peer-to-peer manner and implement some proximity-based semantics. A typical example of such application can be a radar application where users see their avatar as well as the avatars of their friends on a map on their mobile phone. Such application become increasingly popular with the advent of the latest generation of mobile smart phones with their impressive computational power, their peer-to-peer communication capabilities and their location detection technology. Unfortunately, the existing programming support for such applications is limited, hence the need to address this issue in order to alleviate their development burden. This thesis specifically tackles this problem by providing several tools for application development support. First, it provides the location-based publish/subscribe service (LPSS), a communication abstraction, which elegantly captures recurrent communication issues and thus allows to dramatically reduce the code complexity. LPSS is implemented in a modular manner in order to be able to target two different network architectures. One pragmatic implementation is aimed at mainstream infrastructure-based mobile networks, where mobile devices can communicate through fixed antennas. The other fully decentralized implementation targets emerging mobile ad hoc networks (MANETs), where no fixed infrastructure is available and communication can only occur in a peer-to-peer fashion. For each of these architectures, various implementation strategies tailored for different application scenarios that can be parametrized at deployment time. Second, this thesis provides two location-based message diffusion protocols, namely 6Shot broadcast and 6Shot multicast, specifically aimed at MANETs and fine tuned to be used as building blocks for LPSS. Finally this thesis proposes Phomo, a phone motion testing tool that allows to test proximity semantics of ad hoc applications without having to move around with mobile devices. These different developing support tools have been packaged in a coherent middleware framework called Pervaho.

Optimal management of microgrids

Desenvolupament dels models matemàtics necessaris per a controlar de forma òptima la microxarxa existent als laboratoris del Institut de Recerca en Energia de Catalunya. Els algoritmes s'implementaran per tal de simular el comportament i posteriorment es programaran directament sobre els elements de la microxarxa per verificar el seu correcte funcionament.. Desenvolupament dels models matemàtics necessaris per a controlar de forma òptima la microxarxa existent als laboratoris del Institut de Recerca en Energia de Catalunya. Els algoritmes s'implementaran per tal de simular el comportament i posteriorment es programaran directament sobre els elements de la microxarxa per verificar el seu correcte funcionament.

Mechanisms of spindle positioning during "Caenorhabditis elgans" asymmetric cell division

Résumé : Le positionnement correct du fuseau mitotique est crucial pour les divisions cellulaires asymétriques, car il gouverne le contrôle spatial de la division cellulaire et assure la ségrégation adéquate des déterminants cellulaires. Malgré leur importance, les mécanismes contrôlant le positionnement du fuseau mitotique sont encore mal compris. Chez l'embryon au stade une-cellule du nématode Caenorhabditis elegans, le fuseau mitotique est positionné de manière asymétrique durant l'anaphase grâce à l'action de générateurs de force situés au cortex cellulaire, et dont la nature était jusqu'alors indéterminée. Ces générateurs de force corticaux exercent une traction sur les microtubules astraux et sont dépendants de deux protéines Gα et de leurs protéines associées. Cette thèse traite de la nature de la machinerie responsable pour la génération des forces de tractions, ainsi que de son lien avec les protéines Gα et associées. Nous avons combiné des expériences de coupure par faisceau laser du fuseau mitotique avec le contrôle temporel de l'inactivation de gènes ou de l'exposition à des produits pharmacologiques. De cette manière, nous avons établi que la dynéine, un moteur se déplaçant vers l'extrémité négative des microtubules, ainsi que la dynamique des microtubules, sont toutes deux requises pour la génération efficace des forces de tractions. Nous avons démontré que les protéines Gα et leurs protéines associées GPR-1/2 et LIN-5 interagissent in vivo avec LIS-1, un composant du complexe de la dynéine. De plus, nous avons découvert que les protéines Gα, GPR-1/2 et LIN-5 promeuvent la présence du complexe de la dynéine au cortex cellulaire. Nos résultats suggèrent un mécanisme par lequel les protéines Gα permettent le recrutement cortical de GPR-1/2 et LIN-5, assurant ainsi la présence de la dynéine au cortex. Conjointement avec la dynamique des microtubules, ce mécanisme permet la génération des forces de tractions afin d'obtenir une division cellulaire correcte. Comme les mécanismes contrôlant le positionnement du fuseau mitotique et les divisions cellulaires asymétriques sont conservés au cours de l'évolution, nous espérons que les mécanismes élucidés par ce travail sont d'importance générale pour la génération de la diversité cellulaire durant le développement. De plus, ces mécanismes pourraient être applicables à d'autres divisions asymétriques, comme celle des cellules souches, dont le disfonctionnement peut entraîner la génération de cellules cancéreuses. Abstract : Proper spindle positioning is crucial for asymmetric cell division, because it controls spatial aspects of cell division and the correct inheritance of cell-fate determinants. However, the mechanisms governing spindle positioning remain incompletely understood. In the Caenorhabditis elegans one-cell stage embryo, the spindle becomes asymmetrically positioned during anaphase through the action of as-yet unidentified cortical force generators that pull on astral microtubules and that depend on two Gα proteins and associated proteins. This thesis addresses the nature of the force generation machinery and the link with the Gα and associated proteins. By performing spindle-severing experiments following temporally restricted gene inactivation and drug exposure, we established that microtubule dynamics and the minus-end directed motor dynein are both required for generating efficient pulling forces. We discovered that the Gα proteins and their associated proteins GPR-1/2 and LIN-5 interact in vivo with LIS-1, a component of the dynein complex. Moreover, we uncovered that LIN-5, GPR-1/2 and the Gα proteins promote the presence of the dynein complex at the cell cortex. Our findings suggest a mechanism by which the Gα proteins enable GPR-1/2 and LIN-5 recruitment to the cortex, thus ensuring the presence of cortical dynein. Together with microtubule dynamics, this allows pulling forces to be exerted and proper cell division to be achieved. Because the mechanisms of spindle positioning and asymmetric cell division are conserved across evolution, we expect the underlying mechanism uncovered here to be of broad significance for the generation of cell diversity during development. Moreover, this mechanism could be relevant for other asymmetric cell divisions, such as stem cell divisions, whose dysfunction may lead to the generation of cancer cells.

Preliminary evaluation of acid mine drainage in Minas Gerais State, Brazil

Mining in the State of Minas Gerais-Brazil is one of the activities with the strongest impact on the environment, in spite of its economical importance. Amongst mining activities, acid drainage poses a serious environmental problem due to its widespread practice in gold-extracting areas. It originates from metal-sulfide oxidation, which causes water acidification, increasing the risk of toxic element mobilization and water resource pollution. This research aimed to evaluate the acid drainage problem in Minas Gerais State. The study began with a bibliographic survey at FEAM (Environment Foundation of Minas Gerais State) to identify mining sites where sulfides occur. Substrate samples were collected from these sites to determine AP (acidity potential) and NP (neutralization potential). The AP was evaluated by the procedure of the total sulfide content and by oxygen peroxide oxidation, followed by acidity titration. The NP was evaluated by the calcium carbonate equivalent. Petrographic thin sections were also mounted and described with a special view to sulfides and carbonates. Based on the chemical analysis, the acid-base accounting (ABA) was determined by the difference of AP and NP, and the acid drainage potential obtained by the ABA value and the total volume of material at each site. Results allowed the identification of substrates with potential to generate acid drainage in Minas Gerais state. Altogether these activities represent a potential to produce between 3.1 to 10.4 billions of m³ of water at pH 2 or 31.4 to 103.7 billions of m³ of water at pH 3. This, in turn, would imply in costs of US$ 7.8 to 25.9 millions to neutralize the acidity with commercial limestone. These figures are probably underestimated because some mines were not surveyed, whereas, in other cases, surface samples may not represent reality. A more reliable state-wide evaluation of the acid drainage potential would require further studies, including a larger number of samples. Such investigations should consider other mining operations beyond the scope of this study as well as the kinetics of the acid generation by simulated weathering procedures.