The study area in northeast British Columbia extends from the Rocky Mountains in the west to the Fort Nelson Lowland in the east, and includes the westernmost extend of the Laurentide Ice Sheet (LIS) and the easternmost extend of the Cordilleran Ice Sheet (CIS) in the Late Pleistocene. Surficial mapping conducted over portions of the Fontas and Fort Nelson map areas (NTS 094I/SW and 094J/SE, respectively) provides information on sediment distribution and characteristics as well as glacial history. This information has direct implications for geotechnical investigations, aggregate resources and diamond exploration in the region. Non-glacial pre-Late Wisconsinan sediments occur at multiple sites along the Prophet River, providing a pre-glacial or interglacial history for the area. Geochemical analysis and clast lithologies were used to differentiate between sediments derived from the LIS to the east, and Montane/CIS glaciers to the west. The Quaternary stratigraphy of the Prophet River valley indicates the presence of a paleo-Prophet River valley system. Nonglacial deposits in the paleovalley include overbank fines and floodplain sediments interbedded with fluvial gravels. Macrofossils within horizontally laminated organic-rich black clay and silt are interpreted to indicate deposition in the floodplain of the paleo-Prophet River within oxbow-lakes and possibly also sag ponds. The climate is interpreted to be similar to present within a dominantly spruce forest. Wood found at one site provided a radiocarbon date of 49 300±2000 BP, while wood obtained from five other sites provided non-finite radiocarbon ages. In the Late Wisconsinan, the LIS advanced west-southwest into the study area, blocking existing east-flowing regional drainage, and forming an ice-dammed proglacial lake in the Prophet River valley. Ice overrode these sediments and deposited clast-poor clayey-silt till over the entire region. Thicknesses range from less than one metre to greater than twenty metres in the Prophet River valley. In river-cut sections near the Rocky Mountains in the Fort Nelson and Tuchodi Lakes map areas, potassium-feldspar rich granitoid and gneissic clasts, derived from the Canadian Shield, are generally found only east of the foothills, except along the Tetsa River valley. Near the mountain front, in Tuchodi River valley, outwash from Montane/Cordilleran glacial meltwaters was deposited before the LIS advanced and ponded the valley in the Late Wisconsinan. The geochemistry of 303 till samples collected throughout the study area is used to evaluate the regional glacial history inferred from stratigraphic and geomorphic data. Three different geochemical populations are recognized and corroborated by clast lithology (relative percent) from 56 till and glaciofluvial samples. One population, covering the northeast portion of the study area, was likely deposited by the LIS where it extended west into the Rocky Mountain front during the Late Wisconsinan. The second population suggests that the eastern extent of Montane/Cordilleran ice during the Late Wisconsinan was at least to the Rocky Mountain Foothills; however its easternmost position remains unknown. The third population can be attributed to Late Wisconsinan LIS reworking sediment deposited on the Interior Plains by the CIS, either in the Late Wisconsinan or earlier. During early deglaciation, the ice retreated to the east-northeast, impounding local drainage at the ice margin, forming Glacial Lake Prophet in the Fort Nelson map area and Glacial Lake Hay in the Fontas map area. Glacial lakes followed the retreating ice margin and drained through a variety of meltwater channels. The exposed glacial lacustrine plain became a source for sand dunes oriented southeast indicating katabatic paleowinds from the northwest (NTS 094I/SE).

A high-resolution record of organic-walled dinoflagellate cyst production in Guaymas Basin, Gulf of California (Mexico) reveals a complex paleoceanographic history over the last ~40 ka. Guaymas Basin is an excellent location to perform high resolution studies of changes in Late Quaternary climate and paleo-productivity because it is characterized by high primary productivity, high sedimentation rates, and low oxygen bottom waters. These factors contribute to the deposition and preservation of laminated sediments throughout large portions of the core MD02-2515. In this study we document dinoflagellate cyst production at a centennial to millennial scale throughout the Late Quaternary. Based on the cyst assemblages three major dinoflagellate cyst zones, with seven subzones were established. The most dominant dinoflagellate cyst taxa found throughout the core were Brigantedinium spp. and Operculodinium centrocarpum. Dansgaard-Oeschger events 5-8 are inferred in the dinoflagellate cyst records on the basis of increases in warm taxa, such as Spiniferites pachydermus. Preceding and during the Last Glacial Maximum cysts of Polykrikos cf. kofoidii increase in abundance, responding to oceanographic changes in the Gulf of California perhaps caused by a regression in sea-level. Other intervals of interest are the Younger Dryas where cooler conditions are not recorded, and the Holocene which is characterized by the consistent presence of warm water species Stelladinium reidii, Tuberculodinidum vancampoae, Bitectatodinium spongium and an increase in Quinquecuspis concreta. Changes in cyst assemblages, concentrations and species diversity, along with geochemical data reflect major millennial scale climatic and oceanographic changes. / Graduate

Benzalkonium chlorides (BACs) are widely used, broad-spectrum disinfectants and frequently detected in the environment, even at toxic levels for life. Since such disinfectants can induce broad resistance capabilities, BACs may fuel the emergence of antibiotic resistance in the environment. A substantial body of literature has reported that exposure to BACs causes antibiotic resistance; yet, other studies suggest that the resistance linkage is rare, unsystematic, and/or clinically insignificant. Accordingly, whether or not disinfectant exposure mediates antibiotic resistance and, if so, what molecular mechanisms underlie the resistance link remains to be clearly elucidated. Further, understanding how microbial communities degrade BACs is important not only for alleviating the possible occurrence of antibiotic resistance but also reducing the potential risks to environmental and public health. An integrated strategy that combines metagenomics, metatranscriptomics, genetics, and traditional culture-dependent approaches was employed to provide novel insights into these issues. The integrative approach showed that a microbial community exposed to BACs can acquire antibiotic resistance through two mechanisms: i) horizontal transfer of previously uncharacterized efflux pump genes conferring resistance to BACs and antibiotics, which were encoded on a conjugative plasmid and co-selected together upon BACs and ii) selective enrichment of intrinsically multi-drug resistant organisms. Further, a microbial community adapts to BAC exposure via a variety of mechanisms, including selective enrichment of BAC-degrading species and amino acid substitutions and horizontal transfer of genes related to BAC resistance and degradation. The metatranscriptomic data suggests that the BAC-adapted microbial community metabolized BACs by cooperative interactions among its members. More specifically, Pseudomonas nitroreducens cleaved (i.e., dealkylated) BACs, metabolized the alkyl chain (the dealkylated product of BACs), and released benzyldimethylamine (the other product of BACs), which was further metabolized by other community members (e.g., Pseudomonas putida). Collectively, this study demonstrates the role of BACs in promoting antibiotic resistance and advances current understanding of a microbial community degrading BACs. The results of this work have important implications for (appropriate) usage of disinfectants and for assessing, predicting, and optimizing biological engineering processes treating BAC-bearing waste streams.

In this work, we will focus on the quaternary system Cu1-xAgxInSe2 (CAIS) to investigate the effects of silver (Ag) contribution and exchange with copper (Cu) in CuInSe2. This system is located between the ternary semiconducting chalcopyrite compounds CuInSe2 and AgInSe2. These are two most popular materials applied in photovoltaic cells because of their high optical absorption coefficient, which is an important factor for the manufacture of devices, direct energy gap with values Eg ~1.05 and 1.24 eV, respectively, and excellent thermal stabilities in air. As being a quaternary alloy, we expect that Cu1-xAgxInSe2 will show the advantage of a large degree of variation of their properties as a function of the composition, which allows adjusting of the band gap and other properties. We will analyze the behavior of Ag in the structure depending on the annealing and the effects of the Ag exchange to the Cu vacancies in this crystal structure by changing x (Ag content). The crystals will be characterized structurally by X-ray diffraction (XRD). It will be used to prove crystallinity, determine perfection and lattice parameters depending on composition. Surface morphology and stoichiometry will be examined using scanning electron microscope (SEM) equipped with EDXA. Moreover, electrical properties including the temperature dependent electrical conductivity, and carrier concentrations and mobility extracted from Hall effect measurements, and, optical properties including absorption coefficient, photoconductivity, spectral transmission, and optical band gap have been determined to characterize Cu1-xAgxInSe2 thin films deposited using e-beam evaporation technique.

The Vanadium bromide (V/Br) flow cell employs the Br3-/Br- couple in the positive and the V(II)/V(III) couple in the negative half cell. One major issue of this flow cell is bromine gas formation in the positive half cell during charging which results from the low solubility of bromine in aqueous solutions. Bromine complexing agents previously used in the zinc-bromine fuel cell were evaluated for their applicability in V/Br flow cell electrolytes. Three quaternary ammonium bromides: N-ethyl-N-methyl-morpholinium bromide (MEM), N-ethyl-N-methyl-pyrrolidinium bromide (MEP) and Tetra-butyl ammonium bromide (TBA) were studied. It is known that aqueous bromine reacts with quaternary ammonium bromides to form an immiscible organic phase. Depending on the number of quaternary ammonium bromides used and the environmental temperature, the second phase formed will either be solid or liquid. As any solid formation would interrupt the flow cell operation, potential formation of such kind has to be eliminated. Stability tests of simulated V/Br electrolyte with added quaternary ammonium bromides were carried out at 11, 25 and 40 oC. In the absence of bromine, the addition of MEM, MEP and TBA were found to be stable in V/Br electrolytes. However, in the presence of bromine, solid formation was observed in the bromine rich organic phase when the V/Br electrolyte contained a single quaternary ammonium bromide (QBr) compound. For V/Br electrolytes with binary or ternary QBr mixtures containing TBA, the presence of bromine caused a viscous polybromide phase to form at room temperature and the release of bromine gas at higher temperature. Only a binary mixture of MEM and MEP formed a stable liquid organic phase between 11 ?? 40 oC. In this study it was found that V/Br electrolytes containing a binary QBr mixture (0.75M) of MEM and MEP gave the best combination that formed an orange oily layer in the presence of bromine without solidification between 11 ?? 40oC. Furthermore, it was found that samples of V/Br electrolytes containing a ternary QBr mixture, are less effective in bromine capturing if the total QBr concentration was less than 1 M at 40oC, where bromine gas evolution was observed. From electrochemical studies of V3+/V2+, it was found that the addition of MEM and MEP had a minimal effect on the formal potential of the V3+/V2+ couple, the V2+/V3+ transfer coefficient and the diffusion coefficient of V3+. Therefore, MEM and MEP can be added to the negative half-cell of a V/Br flow cell without major interference From linear sweep voltammetry, the kinetics of the Br-/Br3- redox couple was found to be mass transfer controlled. After the addition of MEM and MEP mixture, the exchange current density was found to decrease from 0.013 Acm-2 to 0.01 Acm-2. On the other hand the transfer coefficient before and after MEM and MEP addition was found to be 0.5 and 0.44 respectively. Since the kinetic parameters were not significantly affected by the addition of MEM and MEP mixture, they can be added to the positive half-cell of the V/Br flow cell as bromine complexing agents. The electrochemical studies of both V3+/V2+ and Br-/Br3- showed the addition of MEM and MEP has minimal interference with the redox reactions of the vanadium bromide flow cell. This thesis also investigated the effect of MEM and MEP addition on the cell performance of a lab scale V/Br flow cell using two different membranes (ChiNaf and VF11). Flow cell performance for 2 M V3.7+ + 0.19 M MEM + 0.56 M MEP electrolytes utilising ChiNaf membrane at 10 mAcm-2 produced an energy efficiency of 59%, and this decreased to 43% after 15 cycles. For the static cell utilising VF11 membrane, the addition of MEM and MEP reduced the energy efficiency from 59.7% to 43.4%. It is believed that this is caused by the mass transfer controlled Br-/Br3- couple in the complexed positive half-cell solution. Therefore, uniformity between the organic and aqueous phase is important for flow cells utilising electrolytes with MEM and MEP. Finally, the polarization resistance of a lab scale V/Br flow cell utilising ChiNaf membrane and 2 M V3.7+ electrolytes was found to be slightly higher during cell charging (3.9 cm2) than during the discharge process (3.6 cm2), which is opposed to that in the all-vanadium redox cell.

This thesis resulted in the development of robust chironomid-based transfer-functions for February mean air temperature and the concentration of total nitrogen (TN) in lake-water. The New Zealand transfer-functions for both variables compare favourably with chironomid-based transfer-functions for equivalent variables from elsewhere in the world, and diatom-based transfer-functions for nutrients and lake production from New Zealand. The application of the temperature and TN transfer-functions provided insight into New Zealand climate conditions during the last glacial and served as validation for the reconstructions. Chironomid-based Temperature reconstructions from lake silts preserved in the banks of Lyndon Stream indicate a maximum cooling of ca 4 ℃ between 26.6 and 24.5 ka BP, which is consistent with estimates based on beetles and plant macrofossils. A cooling of 4 ℃ is insufficient to explain the lack of canopy tree pollen in many New Zealand pollen records at this time. Other environmental parameters additional to temperature may have limited the expansion forest cover. The chironomid-based TN reconstructions infer a trend of rapidly deteriorating water-quality in a small doline in north-west Nelson, in the South Island of New Zealand following deforestation immediately surrounding the lake ca. 1970 AD. The overall trend and timing of eutrophication inferred from the chironomids was consistent with other biological proxies and actual observations of changes in lake water quality. The chironomid-based transfer-functions provide a valuable new tool for the study of longterm climate variability and improving our understanding of the response of aquatic ecosystems to long-term natural and human induced environmental change in New Zealand lakes. I have identified some possibilities for future research which should improve the performance of these transfer-functions. The improvement of the chironomid taxonomy and the expansion of the training set should be the highest priorities.

Thesis (Ph. D.)--Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2007. / Kohl, Paul, Committee Chair ; Bottomley, Lawrence, Committee Member ; Eckert, Charles, Committee Member ; Fuller, Tom, Committee Member ; Teja, Amyn, Committee Member.

No description available.

L'Himalaya résultant de la collision indo-asiatique, dans laquelle l'Inde plonge sous le Tibet, initie régulièrement des tremblements de terre destructeurs dont la plupart sont mortel pour les communautés népalaises et limitrophes. Telle une muraille séparant les plaines d’Inde et le haut plateau du Tibet, l’Himalaya façonne la circulation atmosphérique, affectant tant le climat régional que global. Cette thèse vise à se pencher sur l'histoire et l'évolution peu connue du climat et de la sismicité de l'Himalaya, dans une des régions les moins peuplées et la plus reculées du Népal occidental. Dans le contexte de changements climatiques et environnementaux, l'un des aspects les moins bien élucidés de l'histoire de l'Himalaya au cours du Quaternaire supérieur est celui de l'extension des glaciers ainsi que leurs impacts sur l'évolution du paysage. En nous appuyant sur des observations de terrain, sur des datations par nucléides cosmogéniques (10Be) ainsi que des observations satellitaires, nous avons pu estimer l'étendue maximale des glaciers durant le dernier maximum glaciaire. Soutenant ainsi l'hypothèse suivant laquelle la présence de glacier fut relativement plus étendue à l'échelle du Népal occidental mais pas de l’ordre d’une calotte glaciaire. Sur le plan sismologique, l’enjeu à la fois sociale, économique et politique de l’occurrence d’un séisme de magnitude plus élevée que le récent séisme de 2015 dont l’épicentre se situe près de la ville de Gorkha constitue une préoccupation majeure et motive en grande partie cette thèse. Le dernier séisme majeur ayant rompu le Main Frontal Thrust de magnitude supérieure à 8 (Mb) s’est déroulé le 6 juin 1505 et a considérablement impacté la population népalaise et environnante. Le caractère singulier du Népal occidental s’exprimant ainsi par l’hypothèse de la présence d’un hiatus sismique s’étendant sur plus de 500 ans sur base d’archives historiques et d’études paléosismologiques. Dans cette perspective, cette thèse se penche sur deux questions majeures relatives au comportement sismique de l'Himalaya : d'une part, l'hypothèse d'une lacune sismique dans l'Himalaya central et, d'autre part, de la distribution temporelle des séismes au cours de la fin du Quaternaire. A cette fin, une nouvelle approche de recherche, indépendamment du recours aux tranchées paléosismiques, a été mise en œuvre en Himalaya. En utilisant les lacs comme paleoseismomètre, au travers de la collecte de carottes sédimentaires, nous avons pu affiner la résolution temporelle et déceler des séismes à ce jours non répertorié dans les basses de données accessible et ce sur une échelle de 700 ans. La mise en évidence de séismes important (Mw>6.5) non répertorié indique que le Népal occidental connait une activité sismique comparable au centre du Népal et remet en question l’hypothèse d’un gap sismique au centre de l’Himalaya. Sur base d'une carotte sédimentaire plus longue provenant du même lac, nous avons étudié la distribution temporelle des séismes sur une période de 6000 ans, permettant ainsi de mettre en évidence le caractère aléatoire de l’occurrence des séismes constituant un changement de paradigme là où notion de cycle sismique est encore prépondérante. La mise en évidence du caractère aléatoire de l’occurrence des séismes tant à courte échelle de temps (instrumentale) qu’à l’échelle du Quaternaire infirme l’hypothèse du gap sismique au centre de l’Himalaya et mets en évidence le risque permanent pour le million de personnes concernées. Cette thèse s’achève en se penchant sur une possible relation à l’échelle globale entre la variation de taux de séismicité et les changements climatiques au cours de l’Holocène. Nous constatons ainsi que la sismicité globale connu des périodes de séismes accrue sur 7000 ans. Ces périodes de plus fortes activités semblent être synchrone avec la somme des avancées glaciaires de l'Holocène moyen et supérieur. / The Himalayan collision, in which India underthrusts below Tibet, regularly produces major destructive earthquakes in Nepal and its neighboring countries, most of which are fatal to nearby communities. As a wall dividing the Indian plains and the Tibetan plateau, the Himalaya also significantly modifies the atmospheric circulation, affecting both the local and global climate. This thesis explores the poorly known Quaternary history and evolution of Himalayan climate and seismicity, more particularly in the least populated and most remote region of Western Nepal. In terms of climate and environmental change, one of the least understood aspects of Himalayan history during the late Quaternary is the extension of glaciers and their impacts on landscape evolution. Based on field observations, cosmogenic nuclide dating (10Be) and satellite observations, we estimated the maximum extent of glaciers during the Last Glacial Maximum, which supports the hypothesis of a relatively large glacier cover, but not of an extended ice cap, at the scale of Western Nepal. In terms of seismology, the social, economic and political implications of the occurrence of an earthquake of higher magnitude than the recent earthquake of 2015, whose epicenter is located near the city of Gorkha, is a major concern and largely motivates this thesis. The last major earthquake of magnitude greater than 8 (Mb) took place on 6 June 1505 and had a profound impact on the Nepalese population and the surrounding area. In Western Nepal the 1505 event was the last earthquake that ruptured the Main Frontal Thrust according to historical archives and paleoseismological studies, which gave rise to the concept of a seismic gap in western Nepal and adjacent areas in northern India. With this in mind, this thesis addresses two major issues on the Himalayan seismic behavior: on the first hand is the hypothesis of a seismic gap in the central Himalaya and on the second the temporal distribution of earthquakes during the late Quaternary. For this purpose, a new research approach independent of paleoseismic trenches was applied in the Himalaya. By using lakes as paleoseismometers, we were able to refine the temporal resolution and identify earthquakes that had not yet been documented in the accessible databases on a 700-year scale. Our results from Lake Rara highlight significant previously-unknown earthquakes (Mw>6.5) and they reveal that Western Nepal is seismically as active as central Nepal. Furthermore, they call into question the hypothesis of a seismic gap in the central Himalaya. Based on a longer sediment core from the same lake, we studied the temporal distribution of earthquakes over a period of 6000 years, which has highlighted the random nature of the occurrence of earthquakes, constituting a paradigm shift where the notion of seismic cycle is still prevalent. The random nature of the occurrence of earthquakes both on short (instrumental) and Quaternary time scales disproves the hypothesis of the seismic gap in the central Himalaya and underlines the permanent risk for the million people of concern. The final part of this thesis addresses the possible global relationship between seismic rate fluctuations and climate change during the Holocene. Our results show that the global seismicity clustered over 7000 years and appears to be synchronous with the sum of glacial advances through the Mid and Late Holocene.

L'évolution des versants est le résultat de l'action combinée des processus d'altération et de transport sédimentaire. Même si il est généralement admis que l'efficacité de ces processus varie en fonction du climat, la quantification de l'influence climatique sur l'érosion des versants reste encore peu développée aujourd'hui. S'inscrivant dans cette problématique, notre étude est consacrée au développement d'un nouveau modèle numérique d'érosion des versants, ayant pour objectif de mieux représenter, à différentes échelles de temps, les multiples aspects du contrôle climatique sur les processus de transport de sol. Ce modèle numérique permet de simuler l'évolution de l'épaisseur de sol et du relief à l'échelle d'un versant; il repose sur une paramétrisation simple de la production de sol couplée à une paramétrisation multi-processus du transport de sol, qui comprend plusieurs variables en étroite relation avec le climat (débit de ruissellement, épaisseur de couche active). Le calcul de ces variables est réalisé sur base de séries temporelles de précipitation et de température avec l'aide d'un modèle de transfert de chaleur et d'un modèle de bilan hydrologique. Le comportement du modèle a été étudié au travers de quelques exemples génériques et d'analyses de sensibilité. Les résultats obtenus montrent des différences significatives dans la façon dont se comporte chaque processus de transport sous conditions climatiques variables, et également dans la manière dont chaque processus affecte l'érosion globale des versants. Ces résultats mettent ainsi en lumière l'importance de la paramétrisation multi-processus du transport de sol dans la modélisation de la réponse des versants aux changements climatiques. Nous avons également développé une méthode associant le modèle d'érosion de versant à un algorithme d'inversion (Neighbourhood Algorithm). Cette méthode a permis de caractériser de manière quantitative l'évolution des versants ardennais (NE Belgique) lors du dernier cycle glaciaire-interglaciaire, sur base d'un scénario climatique simple et de nombreuses données topographiques et d'épaisseurs de sol. Les résultats de l'inversion produisent des prédictions en accord avec certaines observations sur la morphologie des versants ardennais ainsi qu'avec des taux d'érosion estimés indépendamment sur base de concentrations en isotopes cosmogéniques, même si on montre que la distribution actuelle des épaisseurs de sol ne renferme pas assez d'information pour déterminer entièrement les taux de production et de transport de sol lors des périodes froides et tempérées du dernier cycle climatique. Les résultats de l'inversion suggèrent des taux de transport de sol bien plus élevés lors de la période froide que lors de la période tempérée, produisant une succession de systèmes limités par la production de sol d'une part (période froide), et par le transport de sol d'autre part (période tempérée). Un pic de transport de sol est prédit lors des transitions entre ces périodes. Les résultats laissent également suggérer qu'un équilibre dynamique en terme d'épaisseur de sol a été récemment atteint dans les parties convexes des versants, alors que des sols peu épais observés dans les parties concaves pourraient correspondre à des traces de la distribution des épaisseurs de sol qui prévalait lors de la dernière glaciation. / Hillslope evolution results from the combined action of weathering and sediment transport processes, which are thought to be both influenced by climate. Yet, the strength and nature of the connection between climate and hillslope erosion remain poorly understood at a quantitative level. In this study, we present a new numerical model of soil production and transport, which aims to better represent, at different time scales, the climate control on soil transport. The numerical model operates at the scale of a single hill and predicts the rates of soil thickness and elevation change, by using a simple parametrization of soil production and a multi-process parametrization of soil transport which includes climate-dependent variables (overland flow discharge and active-layer depth). Simple ground heat transfer and water balance models are used for calculating these variables from time-series of precipitation and temperature. The behaviour of the model has been studied through a few simulation examples and sensitivity analysis. The results highlight the importance of considering multi-process parameterization of soil transport when modelling the response of the hillslope system to climate variations, as these results display significant differences on how each transport process behaves under various climatic conditions and on how each process affect the evolution of the system. Our numerical model has also been combined with an inversion scheme (Neighbourhood Algorithm) to extract quantitative information on the evolution of hillslopes in the Ardenne (Belgium, NW Europe) during the Last Glacial-Interglacial Cycle, using a simple climatic scenario and a unique set of topographic and soil thickness data. Model predictions based on inversion results are consistent with independent observations on hillslope morphology and cosmogenic nuclide-derived erosion rates, although the inversion results show that soil production and transport rates under both the cold and warm phases of the last climatic cycle cannot be fully constrained by the present-day soil thickness distribution. The inversion results suggest that soil transport is by far more efficient during the cold climatic phase than during the warm phase, resulting in the succession of weathering-limited (cold phase) and transport-limited (warm phase) systems. Maximum soil transport rates are predicted during the transitions between the cold-warm phases. The results also suggest that a soil thickness dynamic equilibrium has been recently reached on convex regions of the hillslopes, while shallow soils found in convergent areas may be the relics of the soil thickness distribution that formed during the cold phase.