Hydrological and meteorological records from the Vernagtferner Basin - Vernagtbach station, for the years 1970 to 2001

The Vernagtferner region has a long tradition of glaciological research performed by groups from Munich. It started in 1889, when Prof. Sebastian Finsterwalder from the Technical University in Munich produced the first map of a complete glacier based on terrestrial photogrammetry. Since then, numerous maps of the glacier have been made, describing the change in surface elevation for more than a century. These maps form the basis of the geodetic method of glacier mass balance determination, which provides volume changes as average data for the period between two surveys, i.e. typically for 10 years. Since the start of the glaciological method on Vernagtferner in 1964, annual as well as winter and summer mass balance data are available continuously. But only since 1973, the construction of the Vernagtbach station, approximately 1 km below the glacier margin at that time, provided the means to record a larger number of hydrological and meteorological parameters with a temporal resolution of typically 1 hour.

Plant macrofossils from Lac de Fully

We use pollen, stomata and plant-macrofossil records to infer Holocene timberline fluctuations and changes in forest composition at Lac Superieur de Fully (2135 m a.s.l.), a small lake located near the modern regional timberline on a highland plateau in the Central Alps. Our records suggest that during the early Holocene vegetation was rather open on the plateau (eg, heaths of Dryas octopetala, Juniperus nana). The only tree that was able to build major stands was Betula. Other timberline trees (eg, Pinus cembra and Larix) expanded in the catchment of the lake after 8200 cal. BP, when Abies alba expanded at lower elevation. The late appearance of these timberline trees contrasts with previous plant-macrofossil records in the region, which show that the timberline had reached elevations up to at least 2350 m already at 11 000 cal. BP. We suggest that local climatic conditions may have delayed the expansion of closed stands of coniferous trees in the catchment of Lac de Fully until c. 8200 cal. BP, when climate shifted to more humid and less continental conditions. After c. 4600 cal. BP vegetation around the lake primarily responded to human impact, which caused a local lowering of the timberline by at least 150 m.

Sulfur concentrations and isotope ratios in sediments from Kiel Bay, western Baltic Sea

The isotope-ratios of sulfur-components in several sedimentologically different cores of recent marine sediments from Kiel Bay (Baltic Sea) were investigated. In addition, quantitative determinations were made on total sulfur, sulfate, sulfide, chloride, organic carbon, iron and watercontent in the sediment or in the pore-water solution. The investigations gave the following results: 1. The sulfur in the sediment (about 0.3 -2 % of the dry sample) was for the most part introduced into the sediment after sedimentation. This confirms the results of Kaplan et al. (1963, doi:10.1016/0016-7037(63)90074-7). The yield of Sulfur from organic material is very small (in our samples about 5-10% of the total sulfur in the sediment). 2. The sulfur bound in the sediment is taken from the sulfate of the interstitial water. During normal sedimentation, the exchange of sulfate by diffusion significant for changes in the sulfur-content goes down to a sediment depth of 4-6 cm. In this way the sulfate consumed by reduction and formation of sulfide or pyrite is mostly replaced. The uppermost layer of the sediment is an partly open system for the sulfur. The diagenesis of the sulfur is allochemical. 3. The isotope-values of the sediment-sulfur are largely influenced by the sulfur coming into the sediment by diffusion and being bound by bacteriological reduction. Due to the prevailing reduction of 32S and reverse-diffusion of sulfate into the open sea-water, an 32S enrichment takes place in the uppermost layer of the sediment. delta34S-values in the sediment range between -15 and -35 ? while seawater-sulfate has +20 ?. No relationship could be established between sedimentological or chemical changes and isotope-ratios. In the cores, successive sandy and clayly layers showed no change in the delta-values. The sedimentation rate, however, seems to influence isotope-ratios. In one core with low sedimentationrates the delta34S-values varied between -29 and -33 ?, while cores with higher sedimentationrates showed values between -17 and -24 ?. 4. As sediment depth increases, the pore-water sulfate shows decreasing concentrations (in a depth of 30-40 cm we found between 20 and 70 % of the seawater-values), and increasing delta 34S-values (in one case reaching more than +60 ?). The concentration of sulfide in the pore-water increases with sediment-depth (reaching 80 mg S/l in one case). The (delta34S-values of the pore-water-sulfide in all cores show increases paralleling the sulfate sulfur, with a nearly constant delta-distance of 50-60 ? in all cores. This seems to confirm the genetic relationship between the two components.

Volume of natural gas within gas-hydrate and free-gas occurrences in ODP Leg 164 sites

Leg 164 of the Ocean Drilling Program was designed to investigate the occurrence of gas hydrate in the sedimentary section beneath the Blake Ridge on the southeastern continental margin of North America. Sites 994, 995, and 997 were drilled on the Blake Ridge to refine our understanding of the in situ characteristics of natural gas hydrate. Because gas hydrate is unstable at surface pressure and temperature conditions, a major emphasis was placed on the downhole logging program to determine the in situ physical properties of the gas hydrate-bearing sediments. Downhole logging tool strings deployed on Leg 164 included the Schlumberger quad-combination tool (NGT, LSS/SDT, DIT, CNT-G, HLDT), the Formation MicroScanner (FMS), and the Geochemical Combination Tool (GST). Electrical resistivity (DIT) and acoustic transit-time (LSS/SDT) downhole logs from Sites 994, 995, and 997 indicate the presence of gas hydrate in the depth interval between 185 and 450 mbsf on the Blake Ridge. Electrical resistivity log calculations suggest that the gas hydrate-bearing sedimentary section on the Blake Ridge may contain between 2 and 11 percent bulk volume (vol%) gas hydrate. We have determined that the log-inferred gas hydrates and underlying free-gas accumulations on the Blake Ridge may contain as much as 57 trillion m**3 of gas.

A parallel implementation of 3D Zernike moment analysis

Zernike polynomials are a well known set of functions that find many applications in image or pattern characterization because they allow to construct shape descriptors that are invariant against translations, rotations or scale changes. The concepts behind them can be extended to higher dimension spaces, making them also fit to describe volumetric data. They have been less used than their properties might suggest due to their high computational cost. We present a parallel implementation of 3D Zernike moments analysis, written in C with CUDA extensions, which makes it practical to employ Zernike descriptors in interactive applications, yielding a performance of several frames per second in voxel datasets about 2003 in size. In our contribution, we describe the challenges of implementing 3D Zernike analysis in a general-purpose GPU. These include how to deal with numerical inaccuracies, due to the high precision demands of the algorithm, or how to deal with the high volume of input data so that it does not become a bottleneck for the system.

Automated detection and classification of brain injury lesions on structural magnetic resonance imaging

El daño cerebral adquirido (DCA) es un problema social y sanitario grave, de magnitud creciente y de una gran complejidad diagnóstica y terapéutica. Su elevada incidencia, junto con el aumento de la supervivencia de los pacientes, una vez superada la fase aguda, lo convierten también en un problema de alta prevalencia. En concreto, según la Organización Mundial de la Salud (OMS) el DCA estará entre las 10 causas más comunes de discapacidad en el año 2020. La neurorrehabilitación permite mejorar el déficit tanto cognitivo como funcional y aumentar la autonomía de las personas con DCA. Con la incorporación de nuevas soluciones tecnológicas al proceso de neurorrehabilitación se pretende alcanzar un nuevo paradigma donde se puedan diseñar tratamientos que sean intensivos, personalizados, monitorizados y basados en la evidencia. Ya que son estas cuatro características las que aseguran que los tratamientos son eficaces. A diferencia de la mayor parte de las disciplinas médicas, no existen asociaciones de síntomas y signos de la alteración cognitiva que faciliten la orientación terapéutica. Actualmente, los tratamientos de neurorrehabilitación se diseñan en base a los resultados obtenidos en una batería de evaluación neuropsicológica que evalúa el nivel de afectación de cada una de las funciones cognitivas (memoria, atención, funciones ejecutivas, etc.). La línea de investigación en la que se enmarca este trabajo de investigación pretende diseñar y desarrollar un perfil cognitivo basado no sólo en el resultado obtenido en esa batería de test, sino también en información teórica que engloba tanto estructuras anatómicas como relaciones funcionales e información anatómica obtenida de los estudios de imagen. De esta forma, el perfil cognitivo utilizado para diseñar los tratamientos integra información personalizada y basada en la evidencia. Las técnicas de neuroimagen representan una herramienta fundamental en la identificación de lesiones para la generación de estos perfiles cognitivos. La aproximación clásica utilizada en la identificación de lesiones consiste en delinear manualmente regiones anatómicas cerebrales. Esta aproximación presenta diversos problemas relacionados con inconsistencias de criterio entre distintos clínicos, reproducibilidad y tiempo. Por tanto, la automatización de este procedimiento es fundamental para asegurar una extracción objetiva de información. La delineación automática de regiones anatómicas se realiza mediante el registro tanto contra atlas como contra otros estudios de imagen de distintos sujetos. Sin embargo, los cambios patológicos asociados al DCA están siempre asociados a anormalidades de intensidad y/o cambios en la localización de las estructuras. Este hecho provoca que los algoritmos de registro tradicionales basados en intensidad no funcionen correctamente y requieran la intervención del clínico para seleccionar ciertos puntos (que en esta tesis hemos denominado puntos singulares). Además estos algoritmos tampoco permiten que se produzcan deformaciones grandes deslocalizadas. Hecho que también puede ocurrir ante la presencia de lesiones provocadas por un accidente cerebrovascular (ACV) o un traumatismo craneoencefálico (TCE). Esta tesis se centra en el diseño, desarrollo e implementación de una metodología para la detección automática de estructuras lesionadas que integra algoritmos cuyo objetivo principal es generar resultados que puedan ser reproducibles y objetivos. Esta metodología se divide en cuatro etapas: pre-procesado, identificación de puntos singulares, registro y detección de lesiones. Los trabajos y resultados alcanzados en esta tesis son los siguientes: Pre-procesado. En esta primera etapa el objetivo es homogeneizar todos los datos de entrada con el objetivo de poder extraer conclusiones válidas de los resultados obtenidos. Esta etapa, por tanto, tiene un gran impacto en los resultados finales. Se compone de tres operaciones: eliminación del cráneo, normalización en intensidad y normalización espacial. Identificación de puntos singulares. El objetivo de esta etapa es automatizar la identificación de puntos anatómicos (puntos singulares). Esta etapa equivale a la identificación manual de puntos anatómicos por parte del clínico, permitiendo: identificar un mayor número de puntos lo que se traduce en mayor información; eliminar el factor asociado a la variabilidad inter-sujeto, por tanto, los resultados son reproducibles y objetivos; y elimina el tiempo invertido en el marcado manual de puntos. Este trabajo de investigación propone un algoritmo de identificación de puntos singulares (descriptor) basado en una solución multi-detector y que contiene información multi-paramétrica: espacial y asociada a la intensidad. Este algoritmo ha sido contrastado con otros algoritmos similares encontrados en el estado del arte. Registro. En esta etapa se pretenden poner en concordancia espacial dos estudios de imagen de sujetos/pacientes distintos. El algoritmo propuesto en este trabajo de investigación está basado en descriptores y su principal objetivo es el cálculo de un campo vectorial que permita introducir deformaciones deslocalizadas en la imagen (en distintas regiones de la imagen) y tan grandes como indique el vector de deformación asociado. El algoritmo propuesto ha sido comparado con otros algoritmos de registro utilizados en aplicaciones de neuroimagen que se utilizan con estudios de sujetos control. Los resultados obtenidos son prometedores y representan un nuevo contexto para la identificación automática de estructuras. Identificación de lesiones. En esta última etapa se identifican aquellas estructuras cuyas características asociadas a la localización espacial y al área o volumen han sido modificadas con respecto a una situación de normalidad. Para ello se realiza un estudio estadístico del atlas que se vaya a utilizar y se establecen los parámetros estadísticos de normalidad asociados a la localización y al área. En función de las estructuras delineadas en el atlas, se podrán identificar más o menos estructuras anatómicas, siendo nuestra metodología independiente del atlas seleccionado. En general, esta tesis doctoral corrobora las hipótesis de investigación postuladas relativas a la identificación automática de lesiones utilizando estudios de imagen médica estructural, concretamente estudios de resonancia magnética. Basándose en estos cimientos, se han abrir nuevos campos de investigación que contribuyan a la mejora en la detección de lesiones. ABSTRACT Brain injury constitutes a serious social and health problem of increasing magnitude and of great diagnostic and therapeutic complexity. Its high incidence and survival rate, after the initial critical phases, makes it a prevalent problem that needs to be addressed. In particular, according to the World Health Organization (WHO), brain injury will be among the 10 most common causes of disability by 2020. Neurorehabilitation improves both cognitive and functional deficits and increases the autonomy of brain injury patients. The incorporation of new technologies to the neurorehabilitation tries to reach a new paradigm focused on designing intensive, personalized, monitored and evidence-based treatments. Since these four characteristics ensure the effectivity of treatments. Contrary to most medical disciplines, it is not possible to link symptoms and cognitive disorder syndromes, to assist the therapist. Currently, neurorehabilitation treatments are planned considering the results obtained from a neuropsychological assessment battery, which evaluates the functional impairment of each cognitive function (memory, attention, executive functions, etc.). The research line, on which this PhD falls under, aims to design and develop a cognitive profile based not only on the results obtained in the assessment battery, but also on theoretical information that includes both anatomical structures and functional relationships and anatomical information obtained from medical imaging studies, such as magnetic resonance. Therefore, the cognitive profile used to design these treatments integrates information personalized and evidence-based. Neuroimaging techniques represent an essential tool to identify lesions and generate this type of cognitive dysfunctional profiles. Manual delineation of brain anatomical regions is the classical approach to identify brain anatomical regions. Manual approaches present several problems related to inconsistencies across different clinicians, time and repeatability. Automated delineation is done by registering brains to one another or to a template. However, when imaging studies contain lesions, there are several intensity abnormalities and location alterations that reduce the performance of most of the registration algorithms based on intensity parameters. Thus, specialists may have to manually interact with imaging studies to select landmarks (called singular points in this PhD) or identify regions of interest. These two solutions have the same inconvenient than manual approaches, mentioned before. Moreover, these registration algorithms do not allow large and distributed deformations. This type of deformations may also appear when a stroke or a traumatic brain injury (TBI) occur. This PhD is focused on the design, development and implementation of a new methodology to automatically identify lesions in anatomical structures. This methodology integrates algorithms whose main objective is to generate objective and reproducible results. It is divided into four stages: pre-processing, singular points identification, registration and lesion detection. Pre-processing stage. In this first stage, the aim is to standardize all input data in order to be able to draw valid conclusions from the results. Therefore, this stage has a direct impact on the final results. It consists of three steps: skull-stripping, spatial and intensity normalization. Singular points identification. This stage aims to automatize the identification of anatomical points (singular points). It involves the manual identification of anatomical points by the clinician. This automatic identification allows to identify a greater number of points which results in more information; to remove the factor associated to inter-subject variability and thus, the results are reproducible and objective; and to eliminate the time spent on manual marking. This PhD proposed an algorithm to automatically identify singular points (descriptor) based on a multi-detector approach. This algorithm contains multi-parametric (spatial and intensity) information. This algorithm has been compared with other similar algorithms found on the state of the art. Registration. The goal of this stage is to put in spatial correspondence two imaging studies of different subjects/patients. The algorithm proposed in this PhD is based on descriptors. Its main objective is to compute a vector field to introduce distributed deformations (changes in different imaging regions), as large as the deformation vector indicates. The proposed algorithm has been compared with other registration algorithms used on different neuroimaging applications which are used with control subjects. The obtained results are promising and they represent a new context for the automatic identification of anatomical structures. Lesion identification. This final stage aims to identify those anatomical structures whose characteristics associated to spatial location and area or volume has been modified with respect to a normal state. A statistical study of the atlas to be used is performed to establish which are the statistical parameters associated to the normal state. The anatomical structures that may be identified depend on the selected anatomical structures identified on the atlas. The proposed methodology is independent from the selected atlas. Overall, this PhD corroborates the investigated research hypotheses regarding the automatic identification of lesions based on structural medical imaging studies (resonance magnetic studies). Based on these foundations, new research fields to improve the automatic identification of lesions in brain injury can be proposed.

Twentieth century climate change: Evidence from small glaciers

The relation between changes in modern glaciers, not including the ice sheets of Greenland and Antarctica, and their climatic environment is investigated to shed light on paleoglacier evidence of past climate change and for projecting the effects of future climate warming on cold regions of the world. Loss of glacier volume has been more or less continuous since the 19th century, but it is not a simple adjustment to the end of an “anomalous” Little Ice Age. We address the 1961–1997 period, which provides the most observational data on volume changes. These data show trends that are highly variable with time as well as within and between regions; trends in the Arctic are consistent with global averages but are quantitatively smaller. The averaged annual volume loss is 147 mm⋅yr−1 in water equivalent, totaling 3.7 × 103 km3 over 37 yr. The time series shows a shift during the mid-1970s, followed by more rapid loss of ice volume and further acceleration in the last decade; this is consistent with climatologic data. Perhaps most significant is an increase in annual accumulation along with an increase in melting; these produce a marked increase in the annual turnover or amplitude. The rise in air temperature suggested by the temperature sensitivities of glaciers in cold regions is somewhat greater than the global average temperature rise derived largely from low altitude gauges, and the warming is accelerating.

Cerebral energetics and the glycogen shunt: Neurochemical basis of functional imaging

Positron-emission tomography and functional MRS imaging signals can be analyzed to derive neurophysiological values of cerebral blood flow or volume and cerebral metabolic consumption rates of glucose (CMRGlc) or oxygen (CMRO2). Under basal physiological conditions in the adult mammalian brain, glucose oxidation is nearly complete so that the oxygen-to-glucose index (OGI), given by the ratio of CMRO2/CMRGlc, is close to the stoichiometric value of 6. However, a survey of functional imaging data suggests that the OGI is activity dependent, moving further below the oxidative value of 6 as activity is increased. Brain lactate concentrations also increase with stimulation. These results had led to the concept that brain activation is supported by anaerobic glucose metabolism, which was inconsistent with basal glucose oxidation. These differences are resolved here by a proposed model of glucose energetics, in which a fraction of glucose is cycled through the cerebral glycogen pool, a fraction that increases with degree of brain activation. The “glycogen shunt,” although energetically less efficient than glycolysis, is followed because of its ability to supply glial energy in milliseconds for rapid neurotransmitter clearance, as a consequence of which OGI is lowered and lactate is increased. The value of OGI observed is consistent with passive lactate efflux, driven by the observed lactate concentration, for the few experiments with complete data. Although the OGI changes during activation, the energies required per neurotransmitter release (neuronal) and clearance (glial) are constant over a wide range of brain activity.

A visceral pain pathway in the dorsal column of the spinal cord

A limited midline myelotomy at T10 can relieve pelvic cancer pain in patients. This observation is explainable in light of strong evidence in support of the existence of a visceral pain pathway that ascends in the dorsal column (DC) of the spinal cord. In rats and monkeys, responses of neurons in the ventral posterolateral thalamic nucleus to noxious colorectal distention are dramatically reduced after a lesion of the DC at T10, but not by interruption of the spinothalamic tract. Blockade of transmission of visceral nociceptive signals through the rat sacral cord by microdialysis administration of morphine or 6-cyano-7-nitroquinoxaline-2,3-dione shows that postsynaptic DC neurons in the sacral cord transmit visceral nociceptive signals to the gracile nucleus. Retrograde tracing studies in rats demonstrate a concentration of postsynaptic DC neurons in the central gray matter of the L6-S1 spinal segments, and anterograde tracing studies show that labeled axons ascend from this region to the gracile nucleus. A similar projection from the midthoracic spinal cord ends in the gracile and cuneate nuclei. Behavioral experiments demonstrate that DC lesions reduce the nocifensive responses produced by noxious stimulation of the pancreas and duodenum, as well as the electrophysiological responses of ventral posterolateral neurons to these stimuli. Repeated regional blood volume measurements were made in the thalamus and other brain structures in anesthetized monkeys in response to colorectal distention by functional MRI. Sham surgery did not reduce the regional blood volume changes, whereas the changes were eliminated by a DC lesion at T10.

Changes in Salicylic Acid and Antioxidants during Induced Thermotolerance in Mustard Seedlings

Heat-acclimation or salicylic acid (SA) treatments were previously shown to induce thermotolerance in mustard (Sinapis alba L.) seedlings from 1.5 to 4 h after treatment. In the present study we investigated changes in endogenous SA and antioxidants in relation to induced thermotolerance. Thirty minutes into a 1-h heat-acclimation treatment glucosylated SA had increased 5.5-fold and then declined during the next 6 h. Increases in free SA were smaller (2-fold) but significant. Changes in antioxidants showed the following similarities after either heat-acclimation or SA treatment. The reduced-to-oxidized ascorbate ratio was 5-fold lower than the controls 1 h after treatment but recovered by 2 h. The glutathione pool became slightly more oxidized from 2 h after treatment. Glutathione reductase activity was more than 50% higher during the first 2 h. Activities of dehydroascorbate reductase and monodehydroascorbate reductase decreased by at least 25% during the first 2 h but were 20% to 60% higher than the control levels after 3 to 6 h. One hour after heat acclimation ascorbate peroxidase activity was increased by 30%. Young leaves appeared to be better protected by antioxidant enzymes following heat acclimation than the cotyledons or stem. Changes in endogenous SA and antioxidants may be involved in heat acclimation.

A 300 kyr record of upwelling off Oman during the Late Quaternary: evidence of the Asian southwest monsoon

In the northwest Arabian Sea upwelling occurs each summer, driven by the strong SW monsoon winds. Upwelling results in high biological productivity and a distinctive assemblage of plankton species in the surface waters off Oman that are preserved in the sediments along the Oman continental margin, creating a geologic record of monsoon-driven upwelling. Sediments recovered from the Oman continental margin during Ocean Drilling Program leg 117 provide an opportunity to examine how upwelling has varied during the late Quaternary, spanning a longer interval than piston cores recovered prior to the ODP cruise. Variations in foraminifer shell accumulation and in the relative abundance of Globigerina bulloides indicate dominant cycles of variation at 1/100 kyr, the dominant frequency of glacial-interglacial variations, and at 1/23 kyr, the frequency of precessionally driven cycles in seasonal insolation. The strongest monsoon winds (indicated by increased upwelling) occurred during interglacial times when perihelion was aligned with the summer solstice, an orbital change that increased the insolation received during summer in the northern hemisphere. During glacial times upwelling was reduced, and although the precessional cycles were still present their amplitude was smaller. At both frequencies the upwelling cycles are in phase with minimum ice volume, evidence that glacial-interglacial climate changes also include changes to the climate system that influence the low-latitude monsoon. We attribute the decrease in the monsoon winds observed during glacial times to changes in bare land albedo over Asia and/or to changes in the areal extent and seasonal cycle in Asian snow cover that decrease the summer land-sea temperature contrast. Other mechanisms may also be involved. These new upwelling time series differ substantially from previous results, however the previous work relied on cores located farther offshore where upwelling is less intense and other physical mechanisms become important. Our results support the observations derived from atmospheric general circulation models of the atmosphere that indicate that both glacial boundary conditions, and the strength of summer insolation are important variables contributing to cycles in the monsoon winds during the late Quaternary.

Sea surface temperatures derived from alkenones from Late Quaternary sediments of the East Equatorial South Atlantic

Angola Basin and Walvis Ridge records of past sea surface temperatures (SST) derived from the alkenone Uk 37 index are used to reconstruct the surface circulation in the east equatorial South Atlantic for the last 200,000 years. Comparison of SST estimates from surface sediments between 5° and 20°S with modern SST data suggests that the alkenone temperatures represent annual mean values of the surface mixed layer. Alkenone-derived temperatures for the warm climatic maxima of the Holocene and the penultimate interglacial are 1 to 4°C higher than latest Holocene values. All records show glacial to interglacial differences of about 3.5°C in annual mean SST, which is about 1.5°C greater than the difference estimated by CLIMAP (1981) for the eastern Angola Basin. At the Walvis Ridge, significant SST variance is observed at all of the Earth's orbital periodicities. SST records from the Angola Basin vary predominantly at 23- and 100-kyr periodicities. For the precessional cycle, SST changes at the Walvis Ridge correspond to variations of boreal summer insolation over Africa and lead ice volume changes, suggesting that the east equatorial South Atlantic is sensitive to African monsoon intensity via trade-wind zonality. Angola Basin SST records lag those from the Walvis Ridge and the equatorial Atlantic by about 3 kyr. The comparison of Angola Basin and Walvis Ridge SST records implies that the Angola-Benguela Front (ABF) (currently at about 14-16°S) has remained fairly stationary between 12° and 20°S (the limits of our cores) during the last two glacial-interglacial cycles. The temperature contrast associated with the ABF exhibits a periodic 23-kyr variability which is coherent with changes in boreal summer insolation over Africa. These observations suggest that surface waters north of the present ABF have not directly responded to monsoon-modulated changes in the trade-wind vector, that the central field of zonally directed trades in the southern hemisphere was not shifted or extended northward by several degrees of latitude during glacials, and that a cyclonic gyre circulation has existed in the east equatorial South Atlantic over the last 200,000 years. This scenario contradicts former assumptions of glacial intensification of the Benguela Current into the eastern Angola Basin and increased coastal upwelling off Angola.

Heat flow determinations of ODP Hole 111-504B

Hole 504B in the eastern equatorial Pacific has been the focus of five scientific drilling expeditions since it was first drilled in 1979. During these five legs, a series of temperature logs has been obtained over a time span of almost 8 yr, documenting the geothermal and hydrologic state of the oceanic crust in this region. Immediately following reentry at the onset of ODP Leg 111 operations, a high-resolution temperature probe was lowered into the borehole and a precise record of temperature vs. depth in Hole 504B was recorded down to 1300 mbsf. As was observed during previous legs, the temperature gradient in the upper 400 m was reduced, indicating that downhole flow of cool ocean waters through the casing continued, though at a diminished rate. As subhydrostatic pressures in the upper basement have gradually diminished, the volume of flow has decayed from an estimated 6000-7000 L/hr in late 1979 to about 80 L/hr during Leg 111. At depths below 480 mbsf, a predominantly conductive heat transfer environment enabled the temperature gradient log to be analyzed with respect to lithology on both fine and broad scales. Anomalies in the gradient log in the cased section through the sedimentary column were found to correspond to biostratigraphic age markers and/or sharp changes in sediment composition and texture. Broad variations in temperature gradient within the basement correlated with large-scale porosity trends. Conductive heatflow estimates depict a systematic reduction with depth, ranging from approximately 196 mW/m**2 in the sediments to 120 ± 17 mW/m**2 at 1300 mbsf. Possible causes for this observation were examined from several perspectives, but none was suitably convincing. A fluid instability analysis indicated the likely existence of convection cells within the borehole and substantiated the hypothesis of mixing within the borehole postulated from isotopic and chemical studies of borehole waters. However, such mixing of borehole fluids does not provide an adequate explanation for the heatflow variations, and the disparity between surficial and deep values of heat flow remains unresolved.

Carbonate content of sediment core CRP-1 (Table 1)

Determinations of total carbonate content yield additional information, in the context of integrated investigations, thus enabling or enhancing the interpretation and characterisation of the depositional environment, the processes of sedimentation and the diagenesis of sediments. In the case of drillcores, they help us to discern vertical gradations of facies sequences that have repeating patterns or show changes through time. This report presents initial results of carbonate investigations on a total of 32 bulk samples from the Quaternary and Miocene strata of the CRP-1 borehole, which reached a final depth of 147.69 metres below sea floor (mbsf). Fifteen out of a total of 18 lithostratigraphic units in the core were sampled (Tab. 1). Fourteen samples (24.85-43.85 mbsf) belong to the Quaternary, whereas 18 samples (44.53-146.51 mbsf) originate from the Miocene strata. The sampling intervals varied from 1-5 m for the Quaternary, and 1-15 m for the Miocene. All the samples originated from sections of core representing not more than 1 cm thickness.

Interference between propagating changes and its effect on system failure

Computer-based, socio-technical systems projects are frequently failures. In particular, computer-based information systems often fail to live up to their promise. Part of the problem lies in the uncertainty of the effect of combining the subsystems that comprise the complete system; i.e. the system's emergent behaviour cannot be predicted from a knowledge of the subsystems. This paper suggests uncertainty management is a fundamental unifying concept in analysis and design of complex systems and goes on to indicate that this is due to the co-evolutionary nature of the requirements and implementation of socio-technical systems. The paper shows a model of the propagation of a system change that indicates that the introduction of two or more changes over time can cause chaotic emergent behaviour.