Geochemistry and petrology of the volcanic rocks from the Sulu Sea

Major-, trace-, and rare-earth element analyses of the basaltic rocks recovered from the basement of the Sulu Sea and of lithic clasts from the pyroclastic unit representing the acoustic basement of the Cagayan Ridge, are presented. The major and trace elements were measured by X-ray fluorescence techniques, and rare-earth elements by instrumental neutron activation analysis. These data show that the Sulu Sea basalts are back-arc tholeiites and the lithic clasts are basalts, basaltic andesites, and andesites typical of volcanic arc suites erupted on continental crust. Petrogenetic modeling is used to show that the Sulu Sea basalts were derived from a heterogeneous mantle, probably representing subcontinental lithosphere, with contributions from a subduction component. The Sulu Sea is interpreted as a back-arc basin formed by rifting of an Oligocene to early Miocene volcanic arc leaving the Cagayan Ridge as a remnant arc. This event occurred during northward subduction of the Celebes Sea basement beneath the Oligocene to early Miocene arc.

A collaborative filtering approach to mitigate the new user cold start problem.

The new user cold start issue represents a serious problem in recommender systems as it can lead to the loss of new users who decide to stop using the system due to the lack of accuracy in the recommenda- tions received in that first stage in which they have not yet cast a significant number of votes with which to feed the recommender system?s collaborative filtering core. For this reason it is particularly important to design new similarity metrics which provide greater precision in the results offered to users who have cast few votes. This paper presents a new similarity measure perfected using optimization based on neu- ral learning, which exceeds the best results obtained with current metrics. The metric has been tested on the Netflix and Movielens databases, obtaining important improvements in the measures of accuracy, precision and recall when applied to new user cold start situations. The paper includes the mathematical formalization describing how to obtain the main quality measures of a recommender system using leave- one-out cross validation.

An Ant Colony System adaptation to deal with accessibility issues after a disaster

One of the main problems relief teams face after a natural or man-made disaster is how to plan rural road repair work tasks to take maximum advantage of the limited available financial and human resources. Previous research focused on speeding up repair work or on selecting the location of health centers to minimize transport times for injured citizens. In spite of the good results, this research does not take into account another key factor: survivor accessibility to resources. In this paper we account for the accessibility issue, that is, we maximize the number of survivors that reach the nearest regional center (cities where economic and social activity is concentrated) in a minimum time by planning which rural roads should be repaired given the available financial and human resources. This is a combinatorial problem since the number of connections between cities and regional centers grows exponentially with the problem size, and exact methods are no good for achieving an optimum solution. In order to solve the problem we propose using an Ant Colony System adaptation, which is based on ants? foraging behavior. Ants stochastically build minimal paths to regional centers and decide if damaged roads are repaired on the basis of pheromone levels, accessibility heuristic information and the available budget. The proposed algorithm is illustrated by means of an example regarding the 2010 Haiti earthquake, and its performance is compared with another metaheuristic, GRASP.

Evolución de la vegetación en el sector biogeográfico Castellano Cantábrico durante el Cuaternario Final, a través del registro tobáceo

En esta memoria de Tesis Doctoral se aborda el estudio paleobotánico de seis yacimientos tobáceos situados en las localidades burgalesas de Tubilla del Agua, Sedano, Herrán, Tobera y Frías, y en la alavesa de Ocio. El registro fósil encontrado en estos afloramientos se analiza de forma conjunta con el objetivo de conocer la evolución de la vegetación en el sector biogeográfico Castellano Cantábrico. Este sector se considera el territorio para el cual los hallazgos paleobotánicos son representativos y extrapolables, en tanto que constituye una región homogénea desde el punto de vista florístico, que abarca todos los yacimientos prospectados. El contexto temporal en el que se enmarca este estudio es el final del Cuaternario, desde el Pleistoceno Medio hasta la actualidad. Este intervalo se ha establecido a partir de la edad de los depósitos estudiados, la cual ha sido determinada —para los yacimientos de los que no se disponía de edades fiables— mediante la datación de muestras extraídas de las diferentes unidades litológicas identificadas. Para ello han sido empleadas las técnicas de carbono-14, desequilibrio de las series del uranio y racemización de aminoácidos. Los resultados geocronológicos obtenidos junto con el análisis geomorfológico de los yacimientos han permitido vincular la génesis de las 13 unidades litológicas identificadas con diferentes estadíos climáticos. Estos abarcan un amplio rango de condiciones ambientales, desde las más extremas del Último Máximo Glacial, hasta las más benignas de los Estadíos Isotópicos Marinos interglaciares 1 y 5. Como resultado de la prospección de los depósitos de toba fueron recuperados 1.820 fósiles, la mayoría impresiones foliares, pero también moldes de estróbilos femeninos, ramas y corteza, así como 42 carbones y restos subfósiles de Pinus sp. La identificación taxonómica de estos restos se ha realizado fundamentalmente a partir del análisis de caracteres diagnósticos morfológicos. Como resultado de ello, han sido descritos 28 taxones pertenecientes a las subclases Bryidae, Polypodiidae, Pinidae y Magnoliidae. La flora de los yacimientos estudiados se puede clasificar en tres grupos en función de sus requerimientos ecológicos: (i) uno formado por dos especies de alta tolerancia a la continentalidad —Pinus nigra y Quercus faginea—, las cuales aparecen bien representadas en la mayoría de los depósitos; (ii) otro constituido fundamentalmente por un conjunto de árboles y arbustos que habitualmente tienen el papel de especies acompañantes en los bosques ibéricos submediterráneos y eurosiberianos; y (iii) un tercer grupo compuesto por taxones hidrófitos o edafohigrófilos asociados al ecosistema del fitohermo activo y la vegetación de ribera. En el capítulo de Discusión se propone y analiza la hipótesis de que P. nigra y Q. faginea habrían sido las especies protagonistas de la vegetación zonal del sector Castellano Cantábrico durante el Cuaternario Final. Estas podrían haber persistido como tal incluso durante las épocas más frías, debido a su amplia valencia ecológica y a la capacidad de reproducirse vegetativamente en el caso del quejigo. Por el contrario, los taxones mesofíticos y eurosiberianos pudieron haber sufrido la expansión y retracción de sus poblaciones al ritmo de las oscilaciones climáticas. Sin embargo, la orografía diversa del sector Castellano Cantábrico proporciona emplazamientos en los que se combinan las diversas variables fisiográficas, de tal forma que pudieron haber existido microrrefugios en los que encontraron cobijo algunos taxones mesotérmicos y eurosiberianos durante los periodos glaciales. Por último, la historia evolutiva reciente de la vegetación de este territorio ha estado marcada por la acción antrópica, la cual empezó a ser manifiesta a partir del Neolítico. Esta se tradujo en la degradación y reducción de la cubierta forestal, así como en la extinción del pino laricio del Sector Castellano Cantábrico en los dos últimos milenios. ABSTRACT This PhD Dissertation focuses in the study of six tufa formations located nearby the villages of Tubilla del Agua, Sedano, Herrán, Tobera y Frías, all of them in the province of Burgos, and Ocio, which belongs to the province of Álava. We analyze the palaeobotanical archives of these sites with the purpose of unveiling and understanding the evolution of the vegetation of the Castilian Cantabrian biogeographical sector. This area is considered to be the territory that is represented in the palaeobotanical sample of the studied tufa archives. It is the homogeneous phitogeographical area with the lowest rank that include all the sites. The time frame of this study is the last part of the Quaternary, since the Middle Pleistocene to the present time. This interval is defined by the age of the tufa deposits, which were dated —for the ones that there were not available datings— throughout the analysis of 20 tufa samples taken from the 13 identified lithostratigraphic units. The age of the samples has been determined by using the methods of radiocarbon, U-Th dating and amino acid racemization. Chronological results, along with the chronostratigraphic study of the sites has allowed us to relate the build-up of the 13 identified lithostratigraphic units with different climatic stages. These structures were deposited in a wide range of climatic conditions, from the most extreme ones of the Last Glacial Maximum, to the warmer ones of the Marine Isotopic Stages 1 and 5. A total of 1,820 fossils were recovered from the tufa deposits, most of them were leaf impressions, but also pine cones, branches and bark moulds, along with charcoal and Pinus nigra macro remains. The taxonomical identification of these remains has been done mainly through the analysis of morphological traits. As a result of this process, 28 taxa belonging to the subclass of Bryidae, Polypodiidae, Pinidae and Magnoliidae were identified. The persistency of some taxa can be traced along different climatic stages in this fossil record. This fossil flora can be classified in three different groups: (i) the first one would be composed of two species with high continental climate tolerance —Pinus nigra y Quercus faginea—, which can be found in most of the deposits, (ii) the second group would be mostly formed by trees and shrubs that usually grow in the Iberian forests as an accessory species and (iii) the third one is composed of hydrophytes or hydrophilic taxa associate to the streams, riparian zones or the active tufa ecosystem. In the Discussion chapter we propose and analyse the hypothesis that P.nigra and Q. faginea were the main species of the zonal vegetation of the Castilian Cantabrian biogeographical sector during the last part of the Quaternary. This species could have persisted due to their wide ecological amplitude and also due to the capacity of asexual reproduction in the cases of the oak. On the other hand, mesophitic taxa could have suffered the retraction and expansion of their population following the climate oscillations. However, the diverse orography of the Castilian Cantabrian biogeographical sector provides a variety of combinations of physiographic variables, which could have been suitable refuges for some of the mesophitic taxa. The recent evolutionary history of the vegetation in this territory has been affected by human activities, which started to be relevant since the Neolithic. This led to a reduction of the forests and eventually, to the extinction of P. nigra in the Castilian Cantabrian biogeographical sector in the last two thousands of years.

50 Years Ago We Marched: What began on the grounds of Lincoln University, ended on the steps of the Alabama State Capitol

LINCOLN UNIVERSITY - On March 25, 1965, a bus loaded with Lincoln University students and staff arrived in Montgomery, Ala. to join the Selma march for racial and voting equality. Although the Civil Rights Act of 1964 was in force, African-Americans continued to feel the effects of segregation. The 1960s was a decade of social unrest and change. In the Deep South, specifically Alabama, racial segregation was a cultural norm resistant to change. Governor George Wallace never concealed his personal viewpoints and political stance of the white majority, declaring “Segregation now, segregation tomorrow, segregation forever.” The march was aimed at obtaining African-Americans their constitutionally protected right to vote. However, Alabama’s deep-rooted culture of racial bias began to be challenged by a shift in American attitudes towards equality. Both black and whites wanted to end discrimination by using passive resistance, a movement utilized by Dr. Martin Luther King Jr. That passive resistance was often met with violence, sometimes at the hands of law enforcement and local citizens. The Selma to Montgomery march was a result of a protest for voting equality. The Student Nonviolent Coordinating Committee (SNCC) and the Southern Christian Leadership Counsel (SCLC) among other students marched along the streets to bring awareness to the voter registration campaign, which was organized to end discrimination in voting based on race. Violent acts of police officers and others were some of the everyday challenges protesters were facing. Forty-one participants from Lincoln University arrived in Montgomery to take part in the 1965 march for equality. Students from Lincoln University’s Journalism 383 class spent part of their 2015 spring semester researching the historical event. Here are their stories: Peter Kellogg “We’ve been watching the television, reading about it in the newspapers,” said Peter Kellogg during a February 2015 telephone interview. “Everyone knew the civil rights movement was going on, and it was important that we give him (Robert Newton) some assistance … and Newton said we needed to get involve and do something,” Kellogg, a lecturer in the 1960s at Lincoln University, discussed how the bus trip originated. “That’s why the bus happened,” Kellogg said. “Because of what he (Newton) did - that’s why Lincoln students went and participated.” “People were excited and the people along the sidewalk were supportive,” Kellogg said. However, the mood flipped from excited to scared and feeling intimidated. “It seems though every office building there was a guy in a blue uniform with binoculars standing in the crowd with troops and police. And if looks could kill me, we could have all been dead.” He says the hatred and intimidation was intense. Kellogg, being white, was an immediate target among many white people. He didn’t realize how dangerous the event in Alabama was until he and the others in the bus heard about the death of Viola Liuzzo. The married mother of five from Detroit was shot and killed by members of the Ku Klux Klan while shuttling activists to the Montgomery airport. “We found out about her death on the ride back,” Kellogg recalled. “Because it was a loss of life, and it shows the violence … we could have been exposed to that danger!” After returning to LU, Kellogg’s outlook on life took a dramatic turn. Kellogg noted King’s belief that a person should be willing to die for important causes. “The idea is that life is about something larger and more important than your own immediate gratification, and career success or personal achievements,” Kellogg said. “The civil rights movement … it made me, it made my life more significant because it was about something important.” The civil rights movement influenced Kellogg to change his career path and to become a black history lecturer. Until this day, he has no regrets and believes that his choices made him as a better individual. The bus ride to Alabama, he says, began with the actions of just one student. Robert Newton Robert Newton was the initiator, recruiter and leader of the Lincoln University movement to join Dr. Martin Luther King’s march in Selma. “In the 60s much of the civil rights activists came out of college,” said Newton during a recent phone interview. Many of the events that involved segregation compelled college students to fight for equality. “We had selected boycotts of merchants, when blacks were not allowed to try on clothes,” Newton said. “You could buy clothes at department stores, but no blacks could work at the department stores as sales people. If you bought clothes there you couldn’t try them on, you had to buy them first and take them home and try them on.” Newton said the students risked their lives to be a part of history and influence change. He not only recognized the historic event of his fellow Lincolnites, but also recognized other college students and historical black colleges and universities who played a vital role in history. “You had the S.N.C.C organization, in terms of voting rights and other things, including a lot of participation and working off the bureau,” Newton said. Other schools and places such as UNT, Greenville and Howard University and other historically black schools had groups that came out as leaders. Newton believes that much has changed from 50 years ago. “I think we’ve certainly come a long way from what I’ve seen from the standpoint of growing up outside of Birmingham, Alabama,” Newton said. He believes that college campuses today are more organized in their approach to social causes. “The campus appears to be some more integrated amongst students in terms of organizations and friendships.” Barbara Flint Dr. Barbara Flint grew up in the southern part of Arkansas and came to Lincoln University in 1961. She describes her experience at Lincoln as “being at Lincoln when the world was changing.“ She was an active member of Lincoln’s History Club, which focused on current events and issues and influenced her decision to join the Selma march. “The first idea was to raise some money and then we started talking about ‘why can’t we go?’ I very much wanted to be a living witness in history.” Reflecting on the march and journey to Montgomery, Flint describes it as being filled with tension. “We were very conscious of the fact that once we got on the road past Tennessee we didn’t know what was going to happen,” said Flint during a February 2015 phone interview. “Many of the students had not been beyond Missouri, so they didn’t have that sense of what happens in the South. Having lived there you knew the balance as well as what is likely to happen and what is not likely to happen. As my father use to say, ‘you have to know how to stay on that line of balance.’” Upon arriving in Alabama she remembers the feeling of excitement and relief from everyone on the bus. “We were tired and very happy to be there and we were trying to figure out where we were going to join and get into the march,” Flint said. “There were so many people coming in and then we were also trying to stay together; that was one of the things that really stuck out for me, not just for us but the people who were coming in. You didn’t want to lose sight of the people you came with.” Flint says she was keenly aware of her surroundings. For her, it was more than just marching forward. “I can still hear those helicopters now,” Flint recalled. “Every time the helicopters would come over the sound would make people jump and look up - I think that demonstrated the extent of the tenseness that was there at the time because the helicopters kept coming over every few minutes.” She said that the marchers sang “we are not afraid,” but that fear remained with every step. “Just having been there and being a witness and marching you realize that I’m one of those drops that’s going to make up this flood and with this flood things will move,” said Flint. As a student at Lincoln in 1965, Flint says the Selma experience undoubtedly changed her life. “You can’t expect to do exactly what you came to Lincoln to do,” Flint says. “That march - along with all the other marchers and the action that was taking place - directly changed the paths that I and many other people at Lincoln would take.” She says current students and new generations need to reflect on their personal role in society. “Decide what needs to be done and ask yourself ‘how can I best contribute to it?’” Flint said. She notes technology and social media can be used to reach audiences in ways unavailable to her generation in 1965. “So you don’t always have to wait for someone else to step out there and say ‘let’s march,’ you can express your vision and your views and you have the means to do so (so) others can follow you. Jaci Newsom Jaci Newsom came to Lincoln in 1965 from Atlanta. She came to Lincoln to major in sociology and being in Jefferson City was largely different from what she had grown up with. “To be able to come into a restaurant, sit down and be served a nice meal was eye-opening to me,” said Newsom during a recent interview. She eventually became accustomed to the relaxed attitude of Missouri and was shocked by the situation she encountered on an out-of-town trip. “I took a bus trip from Atlanta to Pensacola and I encountered the worse racism that I have ever seen. I was at bus stop, I went in to be served and they would not serve me. There was a policeman sitting there at the table and he told me that privately owned places could select not to serve you.” Newsom describes her experience of marching in Montgomery as being one with a purpose. “We felt as though we achieved something - we felt a sense of unity,” Newsom said. “We were very excited (because) we were going to hear from Martin Luther King. To actually be in the presence of him and the other civil rights workers there was just such enthusiasm and excitement yet there was also some apprehension of what we might encounter.” Many of the marchers showed their inspiration and determination while pressing forward towards the grounds of the Alabama Capitol building. Newsom recalled that the marchers were singing the lyrics “ain’t gonna let nobody turn me around” and “we shall overcome.” “ I started seeing people just like me,” Newsom said. “I don’t recall any of the scowling, the hitting, the things I would see on TV later. I just saw a sea of humanity marching towards the Capitol. I don’t remember what Martin Luther King said but it was always the same message: keep the faith; we’re going to get where we’re going and let us remember what our purpose is.” Newsom offers advice on what individuals can do to make their society a more productive and peaceful place. “We have come a long way and we have ways to change things that we did not have before,” Newsom said. “You need to work in positive ways to change.” Referencing the recent unrest in Ferguson, Mo., she believes that people become destructive as a way to show and vent anger. Her generation, she says, was raised to react in lawful ways – and believe in hope. “We have faith to do things in a way that was lawful and it makes me sad what people do when they feel without hope, and there is hope,” Newsom says. “Non-violence does work - we need to include everyone to make this world a better place.” Newsom graduated from Lincoln in 1969 and describes her experience at Lincoln as, “I grew up and did more growing at Lincoln than I think I did for the rest of my life.”

Topological challenges to DNA replication: Conformations at the fork

The unwinding of the parental DNA duplex during replication causes a positive linking number difference, or superhelical strain, to build up around the elongating replication fork. The branching at the fork and this strain bring about different conformations from that of (−) supercoiled DNA that is not being replicated. The replicating DNA can form (+) precatenanes, in which the daughter DNAs are intertwined, and (+) supercoils. Topoisomerases have the essential role of relieving the superhelical strain by removing these structures. Stalled replication forks of molecules with a (+) superhelical strain have the additional option of regressing, forming a four-way junction at the replication fork. This four-way junction can be acted on by recombination enzymes to restart replication. Replication and chromosome folding are made easier by topological domain barriers, which sequester the substrates for topoisomerases into defined and concentrated regions. Domain barriers also allow replicated DNA to be (−) supercoiled. We discuss the importance of replicating DNA conformations and the roles of topoisomerases, focusing on recent work from our laboratory.

Desenvolvimento de biossensores enzimáticos amperométricos para a determinação de compostos de importância clínica

Este trabalho descreve a preparação e caracterização de eletrodos modificados com azul da Prússia e materiais relacionados e a sua aplicação na construção de biossensores enzimáticos amperométricos para a detecção de oxalato e de glicose. Os materiais utilizados na modificação dos eletrodos foram azul da Prússia e compostos híbridos formados por hexacianoferrato de níquel e polipirrol ou hexacianoferrato de cobre e polipirrol. Os materiais lubridos mostraram-se capazes de mediar na eletroredução de peróxido de hidrogênio, mesmo em eletrólitos contendo Na+, apresentando melhor desempenho analítico quando comparados aos respectivos hexacianoferratos sem a presença do polímero condutor. Estes materiais foram utilizados com êxito na construção de biossensores para oxalato e para glicose, imobilizando as enzimas Oxalato Oxidase e Glicose Oxidase, respectivamente. Também foi estudada a preparação de um biossensor para a detecção de glicose utilizando a técnica de automontagem eletrostática camada por camada. Esta técnica permite otimizar o processo de immobilização da enzima, obtendo excelente desempenho analítico com pouca quantidade de enzima. Finalmente, são apresentadas a síntese, caracterização e aplicação de nanopartículas de azul da Prússia na determinação de peróxido de hidrogênio. Foi possível preparar nanopartículas com um diâmetro médio de 5 nm, as quais foram imobilizadas em eletrodos mediante a técnica de automontagem eletrostática camada por camada, a fim de estudar seu comportamento eletroquímico.

Dealing with the Fallout: West Germany's Response to the Solange Decision (1974). ACES Working Papers, 2011

The European Union's powerful legal system has proven to be the vanguard moment in the process of European integration. As early as the 1960s, the European Court of Justice established an effective and powerful supranational legal order, beyond the original wording of the Treaties of Rome through the doctrines of direct effect and supremacy. Whereas scholars have analyzed the evolution of EU case law and its implications, only very recent historical scholarship has examined how the Member States received this process in the context of a number of difficult political and economic crises for the integration process. This paper investigates how the national level dealt with these fundamental transformations in the European legal system. Specifically, it examines one of the Union's most important member states, the Federal Republic of Germany. Faced with a huge number of cases dealing with European law, German judges dealt with the supremacy of European law very cautiously, negotiating between increasingly polarized academic, public and ministerial debates on the question throughout the 1960s. By the mid 1970s, the German Constitutional Court famously limited the power of the ECJ in its Solange decision (1974). This was an expression of a broader discourse in Germany from 1968 onwards about the qualitative nature of democracy and participation in public life and was in some aspects a marker, at which the German elites felt comfortable expressing the value of their national constitutional system on the European stage. This paper examines the political, media and academic build up and response to the Constitutional Court's decision in the 1970s, arguing that the national "reception" is central to understanding the dynamics and evolution of European Union legal history.

(Table 1) Neodymium and Strontium measurements from sediment core MD01-2451

In the nineties, cold-water coral mounds were discovered in the Porcupine Seabight (NE Atlantic, west of Ireland). A decade later, this discovery led to the drilling of the entire Challenger cold-water coral mound (Eastern slope, Porcupine Seabight) during IODP Expedition 307. As more than 50% of the sediment within Challenger Mound consists of terrigenous material, the terrigenous component is equally important for the build-up of the mound as the framework-building corals. Moreover, the terrigenous fraction contains important information on the dynamics and the conditions of the depositional environment during mound development. In this study, the first in-depth investigation of the terrigenous sediment fraction of a cold-water coral mound is performed, combining clay mineralogy, sedimentology, petrography and Sr-Nd-isotopic analysis on a gravity core (MD01-2451G) collected at the top of Challenger Mound. Sr- and Nd-isotopic fingerprinting identifies Ireland as the main contributor of terrigenous material in Challenger Mound. Besides this, a variable input of volcanic material from the northern volcanic provinces (Iceland and/or the NW British Isles) is recognized in most of the samples. This volcanic material was most likely transported to Challenger Mound during cold climatic stages. In three samples, the isotopic ratios indicate a minor contribution of sediment deriving from the old cratons on Greenland, Scandinavia or Canada. The grain-size distributions of glacial sediments demonstrate that ice-rafted debris was deposited with little or no sorting, indicating a slow bottom-current regime. In contrast, interglacial intervals contain strongly current-sorted sediments, including reworked glacio-marine grains. The micro textures of the quartz-sand grains confirm the presence of grains transported by icebergs in interglacial intervals. These observations highlight the role of ice-rafting as an important transport mechanism of terrigenous material towards the mound during the Late Quaternary. Furthermore, elevated smectite content in the siliciclastic, glaciomarine sediment intervals is linked to the deglaciation history of the British-Irish Ice Sheet (BIIS). The increase of smectite is attributed to the initial stage of chemical weathering processes, which became activated following glacial retreat and the onset of warmer climatic conditions. During these deglaciations a significant change in the signature of the detrital fraction and a lack of coral growth is observed. Therefore, we postulate that the deglaciation of the BIIS has an important effect on mound growth. It can seriously alter the hydrography, nutrient supply and sedimentation processes, thereby affecting both sediment input and coral growth and hence, coral mound development.

Occurrence of planktic foraminifera in Pliocene to Holocene sediments of DSDP Hole 81-552A in the North Atlantic (Appendix 2)

A new planktic foraminifer transfer function (GSF18) related 5 North Atlantic assemblages to winter and summer sea surface temperature. GSF18, based on recombined and simplified core top census data, preserves most environmental information and reproduces modern North Atlantic conditions with approximately the same accuracy as previous transfer functions, but can be more readily applied to faunal samples ranging in age from Pliocene to Holocene. Transfer function GSF18 has been applied to faunal data from Deep Sea Drilling Project Hole 552A to produce a 2.5 m.y. sea-surface temperature (SST) time series. Estimates show several periods between 2.3 and 4.6 Ma during which mean SST's were both several degrees warmer and several degrees cooler than modern conditions. Between 2.9 and 4.0 Ma SST was generally warmer than modern except for a 250 k.y. interval centered at 3.3 Ma. Maximum SST, with respect to modern conditions, occurred after the cool interval near 3.1 Ma when SST was approximately 3.6° C warmer than present conditions. Comparison of SST estimates with stable isotope data suggest that after peak warming at 3.1 Ma, there was an overall surface water cooling with concomitant build up of global ice volume, culminating in Northern Hemisphere glaciation. This event is also indicated by the presence of ice rafted detritus in 552A sediments at about 2.45 Ma.

Towards identifying the new structures formed on the γ-radiolysis of Ultem

Ultem irradiated up to 10.0 MGy has been analysed using C-13, H-1 and D-2 proton-carbon and proton-proton correlation NMR spectroscopy to shed light on the formation of new structures. Chemical shifts and correlation data were used to determine the structure or partial structures of several new components. The spectra indicated the presence of new groups and structures involving the isopropylidene group, the imide ring, and hydrogen-abstraction reactions. Possible pathways for formation of the new structures are proposed and the G-values for their formation have been estimated. (C) 2003 Elsevier Science Ltd. All rights reserved.

Minimising cold damage during reproductive development among temperate rice genotypes. II. Genotypic variation and flowering traits related to cold tolerance screening

Low temperature during microspore development increases spikelet sterility and reduces grain yield in rice (Oryza sativa L.). The objectives of this study were to determine genotypic variation in spikelet sterility in the field in response to low-temperature and then to examine the use of physio-morphological traits at flowering to screen for cold tolerance. Multiple-sown field experiments were conducted over 4 consecutive years in the rice-growing region of Australia to increase the likelihood of encountering low-temperature during microspore development. More than 50 cultivars of various origins were evaluated, with 7 cultivars common to all 4 years. The average minimum temperature for 9 days during microspore development was used as a covariate in the analysis to compare cultivars at a similar temperature. The low-temperature conditions in Year 4 identified cold-tolerant cultivars such as Hayayuki and HSC55 and susceptible cultivars such as Sasanishiki and Doongara. After low temperature conditions, spikelet sterility was negatively correlated with the number of engorged pollen grains, anther length, anther area, anther width, and stigma area. The number of engorged pollen grains and anther length were found to be facultative traits as their relationships with spikelet sterility were identified only after cold water exposure and did not exist under non-stressed conditions.

On the thermal stabilization of carbon-supported SiO2 catalysts by phosphorus:evaluation in the oxidative dehydrogenation of ethylbenzene to styrene and a comparison with relevant catalysts

A strategy to enhance the thermal stability of C/SiO2 hybrids for the O2-based oxidative dehydrogenation of ethylbenzene to styrene (ST) by P addition is proposed. The preparation consists of the polymerization of furfuryl alcohol (FA) on a mesoporous precipitated SiO2. The polymerization is catalyzed by oxalic acid (OA) at 160 °C (FA:OA = 250). Phosphorous was added as H3PO4 after the polymerization and before the pyrolysis that was carried out at 700 °C and will extend the overall activation procedure. Estimation of the apparent activation energies reveals that P enhances the thermal stability under air oxidation, which is a good indication for the ODH tests. Catalytic tests show that the P/C/SiO2 hybrids are readily active, selective and indeed stable in the applied reactions conditions for 60 h time on stream. Coke build-up during the reaction attributed to the P-based acidity is substantial, leading to a reduction of the surface area and pore volume. The comparison with a conventional MWCNT evidences that the P/C/SiO2 hybrids are more active and selective at high temperatures (450–475 °C) while the difference becomes negligible at lower temperature. However, the comparison with reference P/SiO2 counterparts shows a very similar yield than the hybrids but more selective to ST. The benefit of the P/C/SiO2 hybrid is the lack of stabilization period, which is observed for the P/SiO2 to create an active coke overlayer. For long term operation, P/SiO2 appears to be a better choice in terms of selectivity, which is crucial for commercialization.

Combined bioreaction and separation in centrifugal fields

The aim of this work has been to investigate the principle of combined centrifugal bioreaction-separation. The production of dextran and fructose by the action of the enzyme dextransucrase on sucrose was employed to elucidate some of the principles of this type of process. Dextran is a valuable pharmaceutical product used mainly as a blood volume expander and blood flow improver whilst fructose is an important dietary product. The development of a single step process capable of the simultaneous biosynthesis of dextran and the separation of the fructose by-product should improve dextran yields whilst reducing capital and processing costs. This thesis shows for the first time that it is possible to conduct successful bioreaction-separations using a rate-zonal centrifugation technique. By layering thin zones of dextrasucrase enzyme onto sucrose gradients and centrifuging, very high molecular weight (MW) dextran-enzyme complexes were formed that rapidly sedimented through the sucrose substrate gradients under the influence of the applied centrifugal field. The low MW fructose by-product sedimented at reduced rates and was thus separated from the enzyme and dextran during the reaction. The MW distribution of dextran recovered from the centrifugal bioreactor was compared with that from a conventional batch bioreactor. The results indicated that the centrifugal bioreactor produced up to 100% more clinical dextran with MWs of between 12 000 and 98 000 at 20% w/w sucrose concentrations than conventional bioreactors. This was due to the removal of acceptor fructose molecules from the sedimenting reaction zone by the action of the centrifugal field. Higher proportions of unwanted lower MW dextran were found in the conventional bioreactor than in the centrifugal bioreactor-separator. The process was studied on a number of alternative centrifugal systems. A zonal rotor fitted with a reorienting gradient core proved most successful for the evaluation of bioreactor performance. Results indicated that viscosity build-up in the reactor must be minimised in order to increase the yields of dextran per unit time and improve product separation. A preliminary attempt at modelling the process has also been made.

Coupled heat and mass transfer in concrete exposed to fire

The first investigation of this study is concerned with the reasonableness of the assumptions related to diffusion of water vapour in concrete and with the development of a diffusivity equation for heated concrete. It has been demonstrated that diffusion of water vapour does occur in concrete at all temperatures and that the type of diffusion is concrete is Knudsen diffusion. Neglecting diffusion leads to underestimating the pressure. It results in a maximum pore pressure of less than 1 MPa. It has also been shown that the assumption that diffusion in concrete is molecular is unreasonable even when the tortuosity is considered. Molecular diffusivity leads to overestimating the pressure. It results in a maximum pore pressure of 2.7 MPa of which the vapour pressure is 1.5 MPa while the air pressure is 1.2 MPa. Also, the first diffusivity equation, appropriately named 'concrete diffusivity', has been developed specifically for concrete that determines the effective diffusivity of any gas in concrete at any temperature. In thick walls and columns exposed to fire, concrete diffusivity leads to a maximum pore pressures of 1.5 and 2.2 MPa (along diagonals), respectively, that are almost entirely due to water vapour pressure. Also, spalling is exacerbated, and thus higher pressures may occur, in thin heated sections, since there is less of a cool reservoir towards which vapour can migrate. Furthermore, the reduction of the cool reservoir is affected not only by the thickness, but also by the time of exposure to fire and by the type of exposure, i.e. whether the concrete member is exposed to fire from one or more sides. The second investigation is concerned with examining the effects of thickness and exposure time and type. It has been demonstrated that the build up of pore pressure is low in thick members, since there is a substantial cool zone towards which water vapour can migrate. Thus, if surface and/or explosive spalling occur on a thick member, then such spalling must be due to high thermal stresses, but corner spalling is likely to be pore pressure spalling. However, depending on the exposure time and type, the pore pressures can be more than twice those occurring in thick members and thought to be the maximum that can occur so far, and thus the enhanced propensity of pore pressure spalling occurring on thin sections heated on opposite sides has been conclusively demonstrated to be due to the lack of a cool zone towards which moisture can migrate. Expressions were developed for the determination of the maximum pore pressures that can occur in different concrete walls and columns exposed to fire and of the corresponding times of exposure.