Tesi sul tema "Earth Sciences"

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2000.
Includes bibliographical references.
The study of Streaming potentials has applications in the earth sciences, ranging from fluid flow monitoring, to permeability determination, to studying the surface chemistry of rocks and minerals. In this thesis study of frequency-dependent electrokinetics is presented with both theoretical development and experimental verification. The complex (real and imaginary) streaming potential coupling coefficient is explained. This is followed by the first experiments to measure the real and imaginary part of frequency-dependent streaming potential coupling coefficients. As part of this study an experimental apparatus and data acquisition system were constructed to measure the streaming potential coupling coefficients as a function of frequency. The purpose of the experiments was to measure, for the first time, the real and imaginary part of streaming potentials. In addition, the measured frequency range was extended beyond any previous measurements. Frequency-dependent streaming potential experiments were conducted on one glass capillary, two porous glass filters, and one rock. The sample pore diameters ranged from 34 micrometers to 1 millimeter. Without these experiments, the validity of modeling of the frequency dependence of the seismoelectric effect using existing models streaming potential models would be in question. Two frequency- dependent models (Packard and Pride) were compared to the data. Both Pride's and Packard's models have a good fit to the experimental data in the low and intermediate frequency regime where viscous terms dominate in the fluid. In the high frequency regime, where inertial terms start to dominate, the data fits the theory after being corrected for capacitance effects of the experimental setup. Pride's generalized model appears to have the ability to more accurately estimate pore sizes in the porous medium samples. Packard's model has one unknown model parameter whereas Pride's model has four unknown model parameters, two of which can be independently determined experimentally. Pride's additional parameters may allow for a determination of permeability. As part of the study of frequency-dependent electrokinetics, this thesis presents the theory for frequency-dependent electro- osmosis. It is shown that the electro- osmosis frequency-dependent coupling coefficient is constant with increasing frequency until the critical frequency is reached, at which point the coupling coefficient starts to decrease with increasing frequency. The frequency response- electro- osmosiso- osmosis coupling coefficient is dependent on the capillary radius. The smaller the capillary radius the higher the critical frequency. Data is presented for a 0.127 mm capillary. In addition to studying frequency-dependent electrokinetics, this thesis examines the temperature-dependent behavior of streaming potential coupling coefficients. As part of this examination a review is made of the previous literature that discusses the temperature dependence of streaming potentials. The streaming potential coupling coefficient is determined using the permittivity, the conductivity, and the viscosity of the fluid. It has been determined that the temperature-dependent behavior of the permittivity, conductivity, and viscosity are well documented and do not alone account for temperature dependence of streaming potentials. The other quantity used in calculating the streaming potential coupling coefficient is the zeta potential. The temperature dependence of the zeta potential is not well understood at the present time. By examining the theory, it appears that the zeta potential temperature dependence is controlled by the fluid concentration and the adsorption properties of the surface. After examining the theory, streaming potential experiments at elevated temperature and pressure were conducted on Fontainebleau Sandstone, Berea Sandstone, and Westerly Granite. The experiments were conducted in a pressure vessel with temperatures ranging from 23° C to 200° C at pore pressure ranging from 20 bar to 50 bar and confining pressures ranging from 200 bar to 250 bar. The zeta potential was found to increase with increasing temperature, and the coupling coefficient can increase or decrease depending on how the conductivity of the sample varies. This implies that in geothermal regions, streaming potentials can have large magnitudes depending on the conductivity of the geothermal fluid.
by Philip M. Reppert.
Ph.D.

In Hong Kong, Earth Sciences are not a regular subject of the secondary school education. The aim of this project is to build up the students’ curiosity, prompting them to explore, investigate and learning more about Earth Science, ultimately attaining a more detailed understanding of where they live: the Earth. .To this end, a set of curriculum supporting materials, including fieldtrip planning, supplementary materials pack and learning outcomes, has been designed in consult with science curriculum co-ordinators, to facilitate both student learning and teaching of Earth Science-related Hong Kong Diploma of Secondary Education (HKDSE) science subjects. Hong Kong Geopark represents a fantastic resource as a “natural science laboratory”, it is an ideal place for students to observe the real processes which are related to the current curriculums in their studies in secondary schools. Ma Shi Chau, one of the geo-sites in the Geopark, was selected as a destination of the fieldwork route in this project,as it provides an easily accessible opportunity to directly observe part of the Geopark’s superb geological landforms, and discover how their formation relates to fundamental principles of Physics, Chemistry and Biology, learned in the Science curriculum of the HKDSE. The set of the curriculum supporting materials was targeted especially for senior secondary students who are studying for the HKDSE in any Hong Kong traditional schools.
published_or_final_version
Applied Geosciences
Master
Master of Science

Geosites representing different geological environments through time, from Triassic to Pleistocene, have been chosen to promote the study of Earth Sciences in schools in the Marche Region, Italy. The project aims at stimulating students and teachers with a different experimental and interdisciplinary approach with the contextual study of chemistry, biology, geology and ecology. The Geosites introduce a variety of geoscience topics and cover the major themes of Earth science courses in Italian schools. The choice of the sites also meets certain requirements (logistics, appeal, availability of data, appropriateness for the age) to facilitate school field trips or to introduce certain topics at the different school levels. By means of the geosites we intend to facilitate and make appealing the teaching of several Earth Sciences topics such as geomorphology, stratigraphy, sedimentology, mineralogy, paleontology, etc.. with a special focus on the topics relevant for the syllabus of the secondary school level. For each geosite, teaching material (general, specific or interdisciplinary) was produced and made available to the teachers through the University of Camerino website, to support them during the study of the Marche geology and of the geosites. The teaching material consists in power point files (to give general and in-depths information), video-clips, interdisciplinary links, proposals of hands-on activities, students' and teachers' questionnaires. The material produced has been presented to the teachers involved in the experimentation and used for the preparation of the field trips dedicated to the teachers and carried out with some of their classes. The questionnaires administered to teachers and students after the activity allowed to implement the teaching material according to the suggestions and the results of the experimentation. With the material created in this project, teachers without a geological background had the chance to become more confident about geosciences and to deepen their knowledge on geological themes and processes, directly related to their own area. They had also the possibility to apply an experimental and interdisciplinary approach, using data from the field trips to find and propose the students some connections between Earth Sciences and other disciplines. In the geosites students had the possibility to be stimulated to apply their theoretical knowledge thanks to the direct observation in the field, increasing their interest in the topics under study. Since the chosen geosites respond to scientific-educational and practical-logistics requirements, students of different age can use them to study scientific topics at different degree of deepening. The teaching material created for the geosites allow to organize school trips in order to observe directly the themes previously studied at school, to collect data and information in the field and to elaborate them back to school. In this project we focused our attention on two geosite: Frasassi (from 210 to 140 million years ago, Quaternary Era) Monte Conero (from Cretacic to Quaternary Era) The reasons for this choice are: - they cover the entire geological history of the Marche region, from 200 Ma up to present day; - they show very significant events of the Earth history; - they allow to analyze several interdisciplinary aspects. Frasassi Geosite. In order to organize the teaching activities for the Frasassi Geosite three geological footpaths have been identified: Frasassi Walk, Beata Virgin of Frasassi trail and M.Valmontagnana trail. To support learners in their study we produced in-depth studies including geological and interdisciplinary aspect offered by the outcrops, the environments and the panorama of the area. Other two power point files, Umbria-Marche Sequence and Frasassi Caves, complete the study of the area with more general information about the geology of the area and the description of the caves. The practical activities to be carried out at this geosite included also the visit of the museum with hands-on activities on fossils. M. Conero Geosite. For the Conero Geosite seven geological footpath have been identified: Passo del Lupo trail, K-Pg boundary Walk, Fornaci Quarries, Massignano Quarry, M.Conero Short walk, Mezzavalle Beach and Portonovo Ring. Similarly to the Frasassi geosite, we produced teaching material. Another interest point, the Sirolo visitor centre, completes the description of the area. The teaching material created in this project was made available to the teachers in the website (http://d7.unicam.it/teachingearthsciences/) For each geosite there is a topographic map with the indication of the trails chosen to describe the geosite and to cover the geosciences topics. The teaching materials consist in: a) principal power point presentations; b) In-depth studies power point presentation of the topics concerning the Frasassi and Conero Geosites; c) photos and sketches of the trails; d) video-clips of the outcrops and of the panorama; e) students' and teachers' activities hand-outs; f) guide sheets; g) questionnaires with or without answers; h) sitography; i) references; j) on line feedback questionnaires. To introduce secondary school teachers to the geosites we organized preparatory courses, seminars and trips in 2013 and 2014. During the field trips, teachers examined in details the trails and the outcrops in order to organize future activities with their classes. At the end of the teachers' activities, we asked them to answer a feedback questionnaire, in order to have their comments and suggestions about the activities proposed about the geosite. The data obtained were used to improve both the teaching materials and the website. Both teachers and students were administered questionnaires at the end of the field trips to evaluate the appreciation of the activities proposed and the geological themes suggested at the geosites, as well as the interdisciplinary aspects evidenced. The results show a high appreciation for the idea to use the regional geosites for improving the knowledge of Earth sciences, although for this type of activity can be very challenging for the teachers without a geological background. Concerning this, the availability of teaching material with precise description of the point of interest for each geosite has been regarded to be very useful to increase the confidence of the teachers in approaching a field trip or even to introduce the local geology to their classes during formal lessons. Moreover, although the teaching material was intended for secondary schools and experimented on schools of this level, it is possible to modulate the materials to be used for middle schools or even primary schools, providing that a selection of the topics is made by the teacher. In the same way the website can be of wider application since it is available to all the people interested to find information on the relevant points in the geosites of their region. This is particularly important to favour the spreading of knowledge of geological phenomena and their implications for the life of the citizens in areas, like Italy, were the geoenvironmental hazards affect heavily the daily life and can put a risk lives and properties. A better knowledge of geosciences, coming from school, can strongly improve the awareness of the Earth as a living planet and guide the behaviours of the future citizens towards the environment. In the Introduction (Chapter 1) is outlined the alarming decline in young people's interest for key science studied, probably due to "the way science of taught in primary and secondary school". Because of this the purpose of this PhD project is to promote the study of the Earth Sciences in school by stimulating students and teachers with an experimental and interdisciplinary approach offered by the geosites. The aims explain the way we intend to proceed to approach this topic. In the following chapters there is the Methodology (Chapter 2) used to select the geosites, the teaching approach, the organization of the project, the visiting of Museum and display centers, the field trips and the production of teaching tools. Each geosite is presented by illustrating the various trails, outcrops, museum and display center included. There is a description of each field trip and of the tools produced to facilitate the teachers’ work. A brief geological introduction for the two Geosites is reported in chapter 3, with all the geoscience points of interest for the schools and the description of the interdisciplinary topics. Diagrams, chart maps and description of the skills acquired by the students with these activities are presented. The Website (chapter 4) includes all the information and the teaching materials regarding the two geosites including the guide cards and the Earth Sciences study in-depth files. For each geosite there are principal power points, study in depth power points, guide cards, video-clips, pictures and images, student and teacher activity hand-outs and questionnaires. In each power point presentation there are curiosity slides (in blue and yellow), several links to study in depth topics, video-clips, photos, activity hand-outs, worksheets, external website links. At the end of each file there are the sitography and the textbooks and general references. Chapter 5 contains the various phases of the research Experimentation, which included: I. presentation of the geosite trails to teachers; II. use of the website; III. visits to the geosites; IV. use of the learning objects; V. the questionnaires of the principal trails; VI. the on-line questionnaire about Frasassi geosite; In the Results (chapter 6) we show the data obtained from the questionnaire administrated proposed to the participants to the project (teachers, secondary school students, IESO selected students and 1st year University students) about:  secondary school teachers refresher courses;  outdoor experiences;  on-line questionnaire feedback about Frasassi geosite. A Discussion (chapter 7) about the results, thanks to tables, figures and charts, shows the impact that the methodology used in this research had on teachers and students. The results obtained allowed also to evidence weaknesses and strengths of the proposed activities which have been used to increase the effectiveness of the teaching material and of the website content. Chapter 8 summarize the Conclusions reached during this project, evidencing the information obtained by the interaction with the science teachers involved in the experimentation and their comments and suggestions. Interesting factors arising from the experimentation with the students were also sources of inputs for the strategy to carry out field and hands-on activities with students of different ages. The Appendices report examples of a hands-on activity, an in-depth study file, a questionnaire, a list of all the materials produced in this project.

This thesis considers atmospheric superrotation, a state of westerly equatorial winds which must be maintained by up-gradient eddy momentum fluxes. Superrotation has appeared in simulations of warm climates that generate enhanced Madden-Julian Oscillation (MJO)-like variability. This led to hypotheses that the warmer atmospheres of the early Pliocene and Eocene may have been superrotating, and that the phenomenon may be relevant to future climate projections.
Earth and Planetary Sciences

This dissertation examines the negotiations involved in justifying science education, particularly those sciences exploring the earth's 'natural resources', in early nineteenth-century England. Locations ranging from the ancient universities, London societies, to parlour-room lectures, education in the earth sciences was deemed useful because it provided the means to 'improve' the nation, both morally and materially. In the context of educational debates, where the means of reproducing knowledge in a hierarchical society was at issue, the distinctions between scientific theory and the practical applications of such knowledge had to be carefully negotiated. Defining principles upon which a gentlemanly, liberal education was based, against the practical, trained, experimental procedures which were demanded for conducting work in the earth sciences was not easily achieved. It was not easy to reach agreement among those concerned with scientific education as to how much practical detail should be taught. This dissertation examines how establishing rules which governed the acquisition and application of knowledge relied upon defining the values of education. One system of science education was developed within the Cambridge curriculum by Edward Daniel Clarke, professor of mineralogy. Clarke considered Cambridge a place for practically preparing students to enter the governing class. During the Napoleonic wars, concerns over national administration ranged from imperial expansion to effectively exploiting the natural resources that sustained the empire. Standardised methods of analysing the potential value of an imperial frontier relied upon education in the earth sciences.

This Thesis describes the synthesis and characterisation of new alkaline earth- and rare earth-transition metal complexes. Experimental and computational studies were performed to investigate the structure and bonding in these complexes. Their reactivity was also studied. Chapter 1 introduces metal-metal bonded complexes and current alkaline earth- and rare earth-transition metal bonded complexes. Chapter 2 describes experimental and computational studies of new alkaline earth- and lanthanide-Fe complexes possessing the [CpFe(CO)2]- anion. Chapter 3 presents experimental studies of the reduction of Fe3(CO)12 with Ca. Chapter 4 describes experimental and computational studies of new alkaline earth- and lanthanide-Co complexes containing the [Co(CO)3(PR3)]- anion. Chapter 5 presents full experimental procedures and characterising data for the new complexes reported. Appendix describes the attempted synthesis of [Ca{CpRu(CO)2}2(THF)x]y and study by DFT of [CaRp2(THF)3]2 CD Appendix contains .cif files for all new crystallographically characterised complexes described.

The present study explores the nature and structure of spiritual and aesthetic experiences through the interdisciplinary application of neurophenomenology (NP). This approach merges aspects of psychology, neurophysiology, and phenomenology into a unified methodology. The study is nested within a larger project, Space, Science, and Spirituality, and as such, it carries a common goal to use simulation to evoke spiritual and aesthetic responses similar to those expressed by astronauts and cosmonauts. Careful analysis of previous work in NP provided methodological “lessons learned”, which guided the experimental design, execution, and analysis of the present study. The data collected provides support for experience as a phenomenon that can be studied through empirical means. Further, the articulation of spiritual and aesthetic experiences akin to astronaut experiences corresponds to specific neurological and psychological indicators. Among those indicators are differences in EEG measures during simulation time relative to expressions of spiritual experience following the simulation and changes in visual processing across theta, alpha, and beta signals as correlated with self-identification. These findings support an embodied theory of experience that incorporates memory, executive function, perception, and consciousness. In addition to its academic contribution, this research holds implications for commercial space flight, long-term space missions, post-traumatic stress disorder therapies, and the entertainment industry.
Ph.D.
Doctorate
Psychology
Sciences
Modeling and Simulation

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2006.
Cataloged from PDF version of thesis. Original thesis missing pages 14, 15, 17, 30 and 31.
Includes bibliographical references (pages 31-32).
Because the lifespan of near-Earth objects (NEOs) is shorter than the age of the solar system, these objects originated elsewhere and they must have a source of re-supply. We seek to determine what fraction of the NEO population consists of dormant or extinct comets. We identify comet candidates among NEOs using three criteria: the Jovian Tisserand parameter Tj < 3, comet nucleus-like spectral parameters (generally linear spectra which correspond to C, D, or P taxonomic types), and low (<0.075) albedos. Out of 31 objects we sample having Tj < 3, we find 17 objects or approximately 55% also satisfy these comet candidate criteria. Bias corrected discovery statistics (Stuart 2003, Ph.D. thesis; Stuart & Binzel 2004, Icarus 170, 295) estimate 30% of the entire NEO population resides in orbits having a value of Tj < 3. Combining these two factors suggests that approximately 16% of the total NEO population has both dynamical and physical properties consistent with a cometary origin.
by Francesca E. DeMeo.
S.B.

This thesis describes new inversion-oriented methodological developments and their seismological applications. In the first study presented the dynamic source parameters of some local Icelandic earthquakes are studied by employing a time domain moment tensor inversion method. A windowing method for direct P and S phases was used and the inversion was performed for frequencies lower than the associated corner frequency under the double-couple constraint. The inversion algorithm could determine the dynamic source parameters correctly, even under conditions of poor azimuthal coverage. The second study deals with a new method for calculating the empirical Green's function based on inversion of earthquake radiation patterns. The resulting Green's functions then may contain both body and surface waves. The validity of the method was then confirmed by applying the method to some Icelandic earthquakes. The lithosphere-asthenosphere transition along the TOR array is investigated in the last two studies. Separate and simultaneous teleseismic P and S relative arrival-time residuals were inverted via different methods (a singular value decomposition and a quadratic programming method) to investigate the reliability and the resolution of the model. The data were corrected a priori for the effect of travel-time perturbations due to crustal structure. The results indicate that the transition between thinner lithosphere in Germany to the thicker Baltic Shield in Sweden occurs in two sharp and steep steps. A sharp and steep subcrustal boundary is found below the Tornquist Zone, with a less significant transition below the Elbe Lineament. The lithospheric structure appears to be about 120 km thick under the Tornquist Zone, increasing to more than 200 km beneath the Baltic Shield.

In order to improve climate- and weather forecasting models, a better knowledge of the physical processes taking place in the lowest part of the atmosphere over the oceans is essential. In these models it is often assumed that the atmospheric boundary layer over sea behaves in the same way as that over land. But, the results show that the processes over sea are significantly different, which has to be accounted for in the models.

By using long term measurements it is shown that the surface waves play a very important role for the turbulent structure in the marine atmospheric boundary layer. For example, they give rise to a height structure that can not be found over land. A consequence of this is that measurements from a buoy (at a few meters above the surface) need to be treated different than measurements on a ship (at 10-30 m above the surface).

The wave influence affects the turbulent kinetic energy budget. Besides the height dependency, the imbalance between local production and local dissipation is a function of stability, wave age and wind speed, and the commonly assumed balance can therefore be questioned. This has direct implications for the so called inertial dissipation method, a method often used to determine turbulent fluxes over sea with the aid of measurements from ships and buoys. A comparison with the more direct eddy-correlation method at 10 m height gives that the inertial dissipation method works best for near neutral conditions and growing sea.

Diagenesis and sequence stratigraphy have been formally treated as two separate disciplines in sedimentary petrology. This thesis demonstrates that synergy between these two subjects can be used to constrain evolution of reservoir quality in sandstones. Such integrated approach is possible because sequence stratigraphy provides useful information on parameters such as pore water chemistry, residence time of sediments under certain geochemistry conditions, and detrital composition, which ultimately control diagenesis of sandstones.

Evidence from five case studies and from literature, enabled the development of a conceptual model for the spatial and temporal distribution of diagenetic alterations and related evolution of reservoir quality in sandstones deposited in paralic environments. Diagenetic alterations that have been constrained within the context of sequence stratigraphy include: (i) formation of kaolinite and intragranular porosity, and mechanical infiltration of clay minerals in sandstones lying at variable depths below sequence boundaries, (ii) formation of pseudomatrix and cementation by calcite, dolomite, and siderite in lag deposits at parasequence boundaries, (iii) cementation by kaolinite, pyrite, and calcite in sandstones lying in the vicinity of parasequence boundaries with coal deposits, (iv) formation of glaucony in condensed interval at parasequence boundaries, transgressive and maximum flooding surfaces, (v) formation of berthierine in fluvial-dominated deltaic deposits of the highstand systems tract, (vi) cementation by calcite in bioclastic sandstones of the transgressive systems tract, and (vii) formation of kaolinite in fluvial deposits of the lowstand systems tract. The distribution of such alterations put important constrains for the pattern of burial diagenesis (e.g., formation of chlorite, illite, quartz), related evolution of reservoir quality in sandstones, and distribution of baffles and barriers for fluid flow in the context of sequence stratigraphy.

Field studies encounter several complicating factors not studied in the models. Examples are oblique convergence, heterogeneous materials and thermal softening by intruding magmas. Within the deeply eroded Svecokarelian orogeny, studies in eastern Bergslagen indicate strain accommodation of the N-S orogenic shortening by regional E-W folding and shear along the conjugate Singö Shear Zone and Ornö Banded Series. Rising temperature resulted in migmatites affecting the strain accommodation resulting in decoupling and rotation of folds along one of the deformation zones.

Deformation zones developed in convergent orogens have been studied in both analogue models and in nature. These studies have focused on a number of important factors controlling strain accommodation during orogenesis. The models show that the shape of the leading edge of the indenting continent controls whether the initial suture remains active or if an effective indenter develops, the spacing and number of faults, the width of the orogen and the height of the mountains. All these characteristics depend on the rate and spatial distribution of erosion and sedimentation. Erosion decreases the importance of effective indenters and favors shearing on existing faults leading to steeper, longer lived shears bounding narrow orogens. If sediments load the margin (e.g. foreland), the thrusts propagate further outboard widening the orogen. The strain that is accommodated by compaction and shearing along deep décollement and conjugate imbricate shears is episodic in time. This work links episodes of increased rates of erosion and sedimentation to episodes of high uplift rates, i.e. the development of new imbricate thrusts or pop-up wedges.

The Forsmark Nuclear Plant is one of the largest in Sweden and produces around one sixth of the total electrical energy in the country. It is situated on the east coast of Sweden in the Uppland region. Nuclear waste has to be properly handled every year and Forsmark is one site proposed for long-term storage of all spent fuel from Swedish nuclear power reactors. This potential high-level repository (a low-level one already exists in the area) will be based on the KBS-3 design process, which consists of 6000 iron-copper capsules where the waste will be stored for 30 years and finally buried 500 m down, isolated from the environment for100.000 years. Before using the disposal site, numerous investigations must be done in the area so the risks are reduced as much as possible. These investigations include drilling of cored boreholes down to 1000 m depth. In this study the KFM01A borehole (figure 1.1) was used with different shot points to analyze possible anisotropy in the subsurface. The anisotropy in rocks can be due to different mechanisms as crystal and mineral grain alignment, crack and pore space alignment and thin layer anisotropy (Rowlands J. et al., 1993). For this purpose a shear wave splitting analysis was done in an attempt to determine both orientation and density of fractures. Shear wave splitting has shown to be a very effective method detecting fractures, providing an unique ability to measure anisotropic seismic attributes that are sensitive to fractures (James E. Gaiser, 2004). This can be useful in many domains as in oil companies to improve reservoir management (James E. Gaiser, 2004) or as an imaging tool in fracture-controlled geothermal reservoirs, to monitor fluid pressure in the cracks and changes in crack density (Tang Chuanhai, 2005). Shear wave splitting studies have also been done in seismology for crustal studies (Rowlands J. et al., 1993). When shear waves enter anisotropic medias they split in two approximately orthogonal components, where the faster and slower components will travel parallel and perpendicular to the fracture planes respectively. The time delay will depend of the amount of anisotropy and the path length. Different methods can be used to evaluate the anisotropy; polarization diagrams (Crampin et al., 1986), linear moveout plots of the horizontal components (Li et al.,1988).The procedure described by Li et al. (1988) are the techniques that are used in the present study. The fractures orientation is also analyzed and compared with the general stress components in the area using well bore information from previous studies, as well as the general tectonic characteristics of the zone.

The tropical hardwood forests of south Florida persist as well-drained patches of broadleaf forest separated by brackish water swamp, marsh, or pineland. In this dissertation, a functional trait approach was used to understand the structure and dynamics of these communities and their responses to abiotic and biotic variation. Twenty-seven permanent plots (20 x 20 m2) were established across the south Florida landscape, representing four sub-regions: Everglades marsh, Long Pine Key, Upper Keys, and Lower Keys. Community weighted mean trait values for four of six selected traits showed significant inter-sub-regional variation. Out of them, three traits (specific leaf area, tree height, and leaf phosphorus) increased significantly from dry and low productivity Florida Keys in the south to the moist and productive areas on the south Florida mainland, while wood density showed the opposite pattern. Trait variance ratios (T-statistic metrics) was used to explore internal filtering (processes that operate within a community) and external filtering (processes that operate at larger scale than that of the individual population or community) on community structure. Both external and internal filtering in the functional composition of south Florida hardwood hammock forest were important for local communities differing in freshwater accessibility, or that occupy different positions along strong edaphic or climatic gradients. To understand the underlying mechanisms that drive species assembly during forest succession in Florida dry sub-tropical forest, 13 leaf, stem, reproductive, and architectural traits of resident tree species across the successional gradient were measured. Tests of null models showed that younger communities are shaped by environmentally driven processes, while mature communities are shaped by competitively driven processes. The overall trait similarities among species present in North Key Largo tropical dry forest suggest that tree species are specialists on the local environment, and their ability to survive and grow in a stressful environment may be more important than competition for resources at larger scale. Moreover, tree species in these forests may exhibit specialization or trait plasticity in coping with drought by changes in their stomatal morphology or activity, allowing for a balance between gas exchange and water loss in a periodically stressful environment. A significant negative correlation between stomatal density and size, and a positive correlation between leaf δ13C and stomatal density were observed across habitat gradient for one of the dominant hardwood hammock species (Bursera simaruba). Small and densely distributed stomates in tandem seems to represent a strategy that allows hammock species to conserve water under physiological drought. Furthermore, findings from this work also showed both intra- and inter-specific trait variation at regional and local scales influence community assembly patterns in hardwood hammock communities in South Florida.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.
Includes bibliographical references (leaves 334-341).
by Lind Shelmerdine Gee.
Ph.D.

Teachers for generations have struggled with the challenge of motivating students to learn in their classes. Literature suggests that a positive way to increase student motivation and academic achievement in science is with the laboratory experience. With the lack of adequate laboratory space in our schools, teachers are having to "make do" in science classes with limited space and budget. A need exists for 9th grade Earth Science laboratory activities that meet county course objectives and yet are simple enough to be used in a classroom setting, thereby eliminating the need for extra expenses for the science department. This project has developed a set of laboratory experiences appropriate for 9th grade Earth Science courses in Duval County.

Thesis (Ph. D.)--George Mason University, 2007.
Title from PDF t.p. (viewed Jan. 17, 2008). Thesis director: Don E. Kash Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Public Policy. Vita: p. 330. Includes bibliographical references (p. 289-329). Also available in print.

Results of visible to near-infrared spectrophotometric observations of 55 near-Earth asteroids (NEAs) are reported. The observing techniques, instrumentation, and method of data analysis are described. A new asteroid classification method that directly compares these NEA spectra with spectral features of meteorites is presented. Two major siliceous groups (having discernible "1-micron" absorptions) result from this method, OC-likes which match the spectra of ordinary chondrites and S-types. The dataset shows a preponderance of spectra consistent with ordinary chondrites (23 NEAs), as well as S-types (19), 2 with spectra consistent with black ordinary chondrites, 2 R-types, and 9 that show no 1-micron absorption.The spectral characteristics of the siliceous S-type and OC-like asteroids blend together, providing evidence that S-type asteroids are simply ordinary chondrites whose surface has been modified by weathering. This helps resolve the long standing question of the lack of main belt asteroids having spectra matching ordinary chondrite meteorites. Main belt asteroids have on average much older surfaces while NEAs that exhibit OC-like spectra have younger surfaces.It was found that fresh objects having spectra consistent with ordinary chondrites (1) occupy mostly highly eccentric Apollo orbits which encounter a strong collisional environment in the asteroid main-belt, (2) may have been recently injected into high eccentricity orbits, or (3) have suffered tidal disruption. S-type NEAs reside primarily in orbits that do not cross the asteroid main-belt. This orbit dependent trend is verified by using the larger NEA dataset of Binzel et al. (2004a).Nine NEAs from this survey exhibiting no 1-micron absorption can be associated with extinct comets, iron meteorites or enstatite meteorites. It is shown that most of these NEAs must be extinct comets, implying a considerably larger fraction of comets among the NEA population than previously thought. A correlation of these objects with low inclination orbits is found.This study finds that the NEA population is divided roughly as follows: ~40% fresh ordinary chondrites, ~35% S-types, ~20% extinct comet candidates, and ~5% in minor classes. This work may guide NEA mitigation planning should such an emergency arise.

Field, experimental and theoretical investigations have been carried out into the electrification of volcanic plumes. At Sakurajima volcano, Japan, ground-level perturbations of the atmospheric electric potential gradient generated by particulate plumes were recorded. Simultaneous measurements, made at up to five sites around the volcano, are shown to be capable of detecting even very small quantities of volcanic particles, and tracking a continuously produced (over a period of several hours), dilute plume as it was dispersed by the wind. Data collected during one small Vulcanian eruption suggest that charges, about 1 C in magnitude, were generated and then separated, with the positive charge centre residing above the negative charge centre. Experiments have been carried out in order to assess fracto-emission (the release of ions, neutral atoms and various frequencies of electromagnetic radiation from fracture surfaces) as a charging mechanism for the electrification of silicate particles in plumes. Silicate particles, generally less than 100 µm in diameter, were produced by colliding pumice samples together and were shown to have net specific charges of approximately 10-5 to 10-6 C kg-1 (similar to previous field measurements on ashfall). Most (but not all) of the experimental samples produced net negatively charged ash, and demonstrated a positive-above-negative charge separation. Additional charge thought to have been released in the form of ions was also detected, supporting fracto-emission as the charging mechanism for volcanic plumes. The magnitude of the net ash charge is shown to be a function of the particle size, with relative humidity having only a small effect. The polarity of the net charge appears to be a function of a property of individual pumice types, possibly their geochemistry. Experiments during which the particles were separated by their polarity indicate that the net charges reflect only a small imbalance in much larger, individual particle charges (10-3 C kg-1) of both polarities. The particle charges are shown to vary with the sample impact velocity, the number of impacts carried out within an experiment and, to a lesser degree, relative humidity. Variation within the results appears to be partly an effect of particle aggregation within the experiment. Investigation of any effects that this particle charging may have on the plumes observed on Io (one of Jupiter’s moons) suggests that luminous discharges and particle aggregation are both probable in this environment. It is shown that the distinct asymmetries observed in plumes are unlikely to be a result of electromagnetic interactions, but probably represent decompression features and asymmetric vent or crater morphologies.

This study, based on a constructivist approach to teaching a difficultpart of the Geology Syllabusfor 16-17 year olds concerned with the Theory of Plate Tectonics attempts to make the teaching process in Earth-sdences easier, more enjoyable and more productive. The first step was to investigate misconceptions held by a sample of 270 students after spedalist teaching concerning the nature and origin of continents, oceans, continental drift, the Earth's magnetic field and plates. The second step involved the designing of a teaching and learning model. This starts with a recognition phase, in which students elicit their views and is followed by reflexion and reconstruction phases which analyse, rethink and reorganize students' knowledge. It ends with a re-evaluation phase. The third step was to plan and implement suitable cuniculum materials.This design incorporated suggestions from the history and epistemology of science and took into account many of the precursor hypotheses and theories which were later subsumed by the all-embradng Theory of Plate Tectonics. Four Units corresponding to each one of the topics referred to above were constructed. The last two units were implemented with an "experimental" group of five students during a five-weekperiod of extra specialist teaching. These studies demonstrate: (i) A rich vein of ideas, tapped before and after the normal period of teaching, which differ from those of the sdentific consensus. Some of these ideas reveal similaritieswith historicalsteps in the construction of Earthsoences ' knowledge and others seem to be imponed from others areas of scence, (ii) The potential of the teaching model as a framework for the designing of curriculum materials; (lii) That materials designed in accordance with the proposed model diminished students' learning difficulties; (iv) That students' conceptual changes were promoted; (iv) A list of precise recommendations which might be used in a normal secondary school's sdence classrooms.

Earth observation satellites provide useful information for early warnings of coming disasters. Theoretically, Principle XI in the Principles Relating to Remote Sensing of the Earth from Outer Space posits that states having access to information about potential natural disasters should promptly transmit this data and its related information to states endangered by the disaster. This thesis analyzes the legal issues related to this duty, liability, remuneration, and the status of international organizations and private entities. It concludes that liability and remuneration issues are unclear. However, due to the time needed to finalize a legally-binding treaty, a United Nations resolution is the way to formulate the regime. Furthermore, the United Nations can promote cooperation between the have and have-not countries, not only in the legal context but also by raising awareness; promoting standardized, compatible data; and supporting the expense of providing remote sensing data to countries without satellites.
Les satellites d'observation de la terre fournissent des informations utiles pour détecter en avance les catastrophes éventuelles. Théoriquement, le principe XI, un des principes sur la télédétection, impose particulièrement que les états ayant accès aux informations sur des catastrophes naturelles potentielles devraient promptement transmettre ces données et son information relative aux états mis en danger par le désastre. Ce mémoire analyse les problématiques liées à ce devoir, à la responsabilité, à la rémunération, et au statut des organismes internationaux et des entités privées. Elle conclut que la responsabilité et la rémunération sont peu claires. Cependant, en raison du temps nécessaire pour conclure un traité juridiquement contraignant, une résolution des Nations Unies paraît comme la manière souhaitable pour formuler ce régime. En outre, les Nations Unies peuvent promouvoir la coopération entre les pays ayant les capacités technologiques et ceux qui ne l’ont pas, non seulement dans le contexte juridique mais également en soulevant la conscience ; en promouvant l’uniformisation et les données compatibles ; et en accordant des aides financières pour les dépenses à fournir des données de télédétection aux pays privés de satellites.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2000.
Includes bibliographical references (p. 61-62).
For subduction to occur, plates must bend and slide past overriding plates along fault zones. This deformation is associated with significant energy dissipation, which changes the energy balance of mantle convection and influences the thermal history of the Earth. To parameterize these effects, a subduction zone was included in a small region of a finite element model for the mantle, which also features an asthenosphere and a mid-oceanic ridge. Velocity boundary conditions were imposed in the vicinity of the subduction. We present theoretical arguments for, and numerical illustrations of the fact that for most modes of deformation, the simple powerlaw relationship of parameterized convection Nu ~ Ra[beta] is not valid anymore, although it is still a good first order approximation. In the case of viscous bending dissipation and non-depth dependent brittle simple shear however, Nu ~ Ra[beta] does hold. [Beta] is less than the value of 1/3 predicted by standard boundary layer theory. For viscous energy dissipation, two different regimes of mantle convection can be considered, depending on the effective viscosity of the lithosphere: the "mobile lid" regime, and the "stagnant lid" regime. For brittle dissipation, the lithosphere strength is a function of yield stress which, when nearing a certain critical value, introduces a third regime, that of the "episodic overturning". Within the "mobile lid" regime, the plate velocities for models with a subduction zone governed by brittle behavior are far less dependent on the plate stress than those models with viscous deformation. This suggests that the plate motion is resisted by viscous stresses in the mantle. The "mobile lid" would be representative for mantle convection associated with plate tectonics, as we observe on Earth. A "stagnant lid" would be the case for the Moon or Mars, while Venus could experience the "episodic overturn" regime featuring cyclic and catastrophic brittle mobilization of a lithosphere with high friction coefficient.
by Pieter Vermeesch.
S.M.

Rezensiertes Werk: Globalisierung, Region und Regionalisierung / Benno Werlen. - Stuttgart : Steiner, 1997. - XI, 464 S. (Sozialgeographie alltäglicher Regionalisierungen ; Bd. 2; Schriftenreihe Erdkundliches Wissen ; 119) ISBN 3-515-06607-1

Rezensiertes Werk: Zillinger, Sylvia: Regionalwirtschaftlicher Strukturwandel und individuelle Arbeitsplatzproblematik : untersucht am Beispiel der Region Heinsberg und der Zeche Sophia-Jacoba / vorgelegt von Sylvia Zillinger, geb. Peters. - Aachen : Maas-Rhein-Inst. für Angewandte Geographie, 1997. - XII, 382 S. : graph. Darst., Kt. (Informationen und Materialien zur Geographie der Euregio Maas, Rhein : Beiheft ; 7) Zugl.: Aachen, Univ., Diss., 1997

Rezensiertes Werk: Weck, Sabine: Neue Kooperationsformen in Stadtregionen : eine regulationstheoretische Einordnung ; das Beispiel München / Sabine Weck. [Hrsg.: Institut für Raumplanung (IRPUD), Fakultät Raumplanung, Universität Dortmund]. - Dortmund : IRPUD; Dortmund : Informationskreis für Raumplanung (IfR), 1995. - 122 S. : Kt. (Dortmunder Beiträge zur Raumplanung : Blaue Reihe ; 74) ISBN 3-88211-093-7

Rezensiertes Werk: Frankfurt am Main: Stadtentwicklung und Architektur : Beobachtung zur Beziehung von Wolkenkratzern zur Stadt / von Werner Bischoff. - Frankfurt a.M. : Inst. für Didaktik der Geographie, 1998. - 57 S. : Ill. - (Bausteine und Materialien ; 1) ISBN 3-921779-16-2

Rezensiertes Werk: Wiegandt, Claus-Christian: An den Grenzen des Wachstums : Eindrücke zur amerikanischen Stadtentwicklung Mitte der 90er Jahre ; Abschlußbericht zur Forschungsreise durch die USA vom 16. Oktober bis zum 8. Dezember 1995 / Claus-C. Wiegandt. Bundesforschungsanstalt für Landeskunde und Raumordnung. - Bonn : Bundesforschungsanst. für Landeskunde und Raumordnung, 1997. - 32 S. : Ill., graph. Darst., Kt. - (Arbeitspapiere / Bundesforschungsanstalt für Landeskunde und Raumordnung ; 1997,3)

Rezensiertes Werk: Vollmar, Rainer: Anaheim - Utopia Americana : vom Weinland zum Walt-Disney-Land ; eine Stadtbiographie ; mit 36 Tabellen / Rainer Vollmar. - Stuttgart : Steiner, 1998. - 289 S. : Ill., graph. Darst., Kt. (Erdkundliches Wissen ; 126) ISBN 3-515-07308-6 (kart.)

Rezensiertes Werk: Nutz, Manfred: Stadtentwicklung in Umbruchsituationen : Wiederaufbau und Wiedervereinigung als Stressfaktor der Entwicklung ostdeutscher Mittelstädte ; ein Raum-Zeit-Vergleich mit Westdeutschland ; mit 7 Tabellen / Manfred Nutz. - Stuttgart : Steiner, 1998. - 242 S. : graph. Darst., Kt. - (Erdkundliches Wissen ; 124) Zugl.: Köln, Univ., Habil.-Schr., 1997 ISBN 3-515-07202-0

Rezensiertes Werk: Auf dem Weg zu einer neuen regionalen Organisation? : Vorträge eines Symposiums in Frankfurt am Main am 20. November 1998 / hrsg. von Klaus Wolf und Elke Tharun. - Frankfurt am Main : Rhein-Mainische Forschung des Inst. für Kulturgeographie, Stadt- und Regionalforschung und des Inst. für Physische Geographie der Johann-Wolfgang-Goethe-Univ., 1999. - 117 S. : graph. Darst., Kt. - (Rhein-Mainische Forschungen ; H. 116 ; Veröffentlichungen der Gesellschaft für Regionalwissenschaftliche Forschung Rhein-Main e.V. ; H. 11) ISBN 3-923184-22-0

Inhalt: 1 Geographie und Globalisierung 2 Sozialwissenschaftliche Geographie 3 Tradition, Spät-Moderne und die wissenschaftliche Geographie 4 Allgemeine Ziele der sozialwissenschaftlichen Geographie 5 Alltägliche Geographien und alltägliche Regionalisierungen 6 Geographien der Produktion und Konsumtion 7 Geographien normativer Aneignung und Kontrolle 8 Geographien der Information und symbolischer Aneignung Schluß

Inhalt: 1 Entdeckung der Region als gesellschaftlicher Raum 2 Das Konzept der regionalen Produktionsmilieus 3 Institutionalisierung von Wirtschaftsregionen -Institutionen als soziales Kapital regionaler Produktionssysteme -Institutionen räumlicher Agglomerationsbildung 4 Wirtschaftsregion als interorganisationales Beziehungssystem -Produktionsverbund -Kontaktsystem -Interessenverbund -Community 5 Regionstypen - Interaktionstypen -Vernetzte Region -Hierarchisch eingebundene Region -Kartellbildung und Auflösung der regionalen Organisation 6 Offene Fragen – Wirtschaftsregionen in der Wissensgesellschaft

Rezensierte Werke: Rohrbach, Christian: Regionale Identität im Global Village : Chance oder Handicap für die Regionalentwicklung? / von Christian Rohrbach. - Frankfurt am Main : Inst. für Kulturgeographie, Stadt- und Regionalforschung der J.-W.-Goethe-Univ., 1999. - 149 S. : graph. Darst., Kt. - (Materialien / Institut für Kulturgeographie, Stadt- und Regionalforschung der J.-W.-Goethe-Universität Frankfurt am Main ; 26 ; Veröffentlichungen der Gesellschaft für regionalwissenschaftliche Forschung Rhein-Main (Regio-Rhein-Main) e. V. ; 12) Zugl.: Frankfurt am Main, Univ., Diplomarbeit, 1998 ISBN 3-923218-19-2 (kart.) Schuhbauer, Jörg: Wirtschaftsbezogene regionale Identität / Jörg Schuhbauer. - Mannheim : Selbstverl. des Geographischen Inst. der Univ. Mannheim, 1996. - XI, 227 S. : graph. Darst. - (Mannheimer geographische Arbeiten ; 42) Zugl.: Mannheim, Univ., Diss., 1996 ISBN 3-923750-63-3 Wolk, Christoph: Regionalgeschichte und Identität : empirische Untersuchungen am Kaiserstuhl / Christoph Wolk. - Frankfurt am Main [u.a.] : Lang, 1998. - 274 S. : graph. Darst. - (Freiburger Beiträge zur Erziehungswissenschaft und Fachdidaktik ; 5) Zugl.: Freiburg (Breisgau), Pädag. Hochsch., Diss., 1997 ISBN 3-631-32780-3 (kart.)