This thesis examines six prominent Pecos River Style rock art anthropomorph attributes to determine if they are found in limited geographic districts of the Lower Pecos Region. Both Boyd (2003) and Turpin (2004) have suggested that spatially-segregated motif distributions exist in the rock art and that these patterns are important in understanding regional prehistoric hunter-gatherer lifeways during the Archaic Period. This study verifies that the feather hip cluster motif is geographically limited, identified only in the neighboring Seminole and Painted Canyon systems. As part of this spatial analysis, the previously undocumented principle of intersite stylistic traditions is introduced. Possible explanations for these anthropomorph attributes are also discussed. Finally, structural analyses of the six attributes are presented.

Many problems of practical significance are known to be NP-hard, and hence, are unlikely to be solved by polynomial-time algorithms. There are several ways to cope with the NP-hardness of a certain problem. The most popular approaches include heuristic algorithms, approximation algorithms, and randomized algorithms. Recently, parameterized computation and complexity have been receiving a lot of attention. By taking advantage of small or moderate parameter values, parameterized algorithms provide new venues for practically solving problems that are theoretically intractable. In this dissertation, we design efficient parameterized algorithms for several wellknown NP-hard problems and prove strong lower bounds for some others. In doing so, we place emphasis on the development of new techniques that take advantage of the structural properties of the problems. We present a simple parameterized algorithm for Vertex Cover that uses polynomial space and runs in time O(1.2738k + kn). It improves both the previous O(1.286k + kn)-time polynomial-space algorithm by Chen, Kanj, and Jia, and the very recent O(1.2745kk4 + kn)-time exponential-space algorithm, by Chandran and Grandoni. This algorithm stands out for both its performance and its simplicity. Essential to the design of this algorithm are several new techniques that use structural information of the underlying graph to bound the search space. For Vertex Cover on graphs with degree bounded by three, we present a still better algorithm that runs in time O(1.194k + kn), based on an “almost-global” analysis of the search tree. We also show that an important structural property of the underlying graphs – the graph genus – largely dictates the computational complexity of some important graph problems including Vertex Cover, Independent Set and Dominating Set. We present a set of new techniques that allows us to prove almost tight computational lower bounds for some NP-hard problems, such as Clique, Dominating Set, Hitting Set, Set Cover, and Independent Set. The techniques are further extended to derive computational lower bounds on polynomial time approximation schemes for certain NP-hard problems. Our results illustrate a new approach to proving strong computational lower bounds for some NP-hard problems under reasonable conditions.

This thesis is focused on the limits of performance of large-scale convex optimization algorithms. Classical theory of oracle complexity, first proposed by Nemirovski and Yudin in 1983, successfully established the worst-case behavior of methods based on local oracles (a generalization of first-order oracle for smooth functions) for nonsmooth convex minimization, both in the large-scale and low-scale regimes; and the complexity of approximately solving linear systems of equations (equivalent to convex quadratic minimization) over Euclidean balls, under a matrix-vector multiplication oracle. Our work extends the applicability of lower bounds in two directions: Worst-Case Complexity of Large-Scale Smooth Convex Optimization: We generalize lower bounds on the complexity of first-order methods for convex optimization, considering classes of convex functions with Hölder continuous gradients. Our technique relies on the existence of a smoothing kernel, which defines a smooth approximation for any convex function via infimal convolution. As a consequence, we derive lower bounds for \ell_p/\ell_q-setups, where 1\leq p,q\leq \infty, and extend to its matrix analogue: Smooth convex minimization (with respect to the Schatten q-norm) over matrices with bounded Schatten p-norm. The major consequences of this result are the near-optimality of the Conditional Gradient method over box-type domains (p=q=\infty), and the near-optimality of Nesterov's accelerated method over the cross-polytope (p=q=1). Distributional Complexity of Nonsmooth Convex Optimization: In this work, we prove average-case lower bounds for the complexity of nonsmooth convex ptimization. We introduce an information-theoretic method to analyze the complexity of oracle-based algorithms solving a random instance, based on the reconstruction principle. Our technique shows that all known lower bounds for nonsmooth convex optimization can be derived by an emulation procedure from a common String-Guessing Problem, which is combinatorial in nature. The derived average-case lower bounds extend to hold with high probability, and for algorithms with bounded probability error, via Fano's inequality. Finally, from the proposed technique we establish the equivalence (up to constant factors) of distributional, randomized, and worst-case complexity for black-box convex optimization. In particular, there is no gain from randomization in this setup.

The lower Trinity River in Texas flows 180 river kilometers from Livingston Dam to Trinity Bay. Like many sandy coastal rivers the lower Trinity is geomorphically active. Within this 180-km reach, the river exhibits three styles of channel geometry and kinematic behavior that have been characterized using aerial photographs spanning the past 60 years, as well as bathymetric surveys and field work completed over the past 5 years. The three channel zones are connected to spatial change in properties of the sediment transport field. The upstream zone is defined by channel-bed incision, relatively small and coarse-grained bars, and relatively low rates of lateral channel migration. These properties of the upstream zone are connected to the discharge of water with effectively no bed-material load from Livingston Dam. Eventually the channel flow scours enough sediment from the channel bed and sidewalls to reestablish the predicted transport capacity for sand in the river, marking the transition to the central zone. This zone is defined by the largest bars and channel bends with the highest rates of lateral migration that persist downstream until the transport of sand and gravel is influenced by the backwater hydraulics connected with the shoreline at Trinity Bay. This downstream river zone is characterized by very small point bars, the deepest flows at most discharges, and lower rates of channel migration. Studying the connections and transitions between these three river zones leads to a more complete understanding of the coevolution of river geometry and profile, channel kinematics, and downstream change in sediment transport in the coastal zone. / text

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The Mississippi River is considered the ultimate single channel meandering river. Five hundred km upstream from its mouth, about 25% of the river’s discharge is diverted into the Atchafalaya River. This diversion is controlled by the Old River Control structure, built by the US Army Corps of Engineers in stages since 1963, to stop the avulsion of the Mississippi River into the Atchafalaya. The study area is a 119 km sandy bedded reach near Old River Control that is highly impacted by engineering measures. Channel dimensions average 1,000 m wide with average thalweg depths of 23 m. The mean annual discharge is 15,000 m3s-1 with a water surface slope of 0.06 m per river mile. In a sandy bedded river, the effective discharge is the discharge which cumulatively transports the most sand. This study evaluates how the Old River Control structure has influenced an adjusting effective discharge between 1978 and 2011. The bed load component of sand transport is included by employing a novel, automated, cross-correlation technique. It was found that the upper limit for discharges that cumulatively transport 85% of the total sand load has decreased from 34,000 m3s-1 to 28,000 m3s-1 between 1978 and 2011. Sand transport from 1982 to 2011 occurred during progressively greater ratios of water discharge to the Atchafalaya River and corresponded to an aggradational trend in the nearby Mississippi River at Red River Landing stream gage. The combination of this sand transport trend and nearby channel aggradation is some indication that the diversion may not be stable and that the avulsion of the lower Mississippi River is ongoing. However, sand was transported at similar discharge ratios in the 1978 to 1982 and 2002 to 2011 periods. Future trends will reveal definitively if these findings indicate that the lower Mississippi River avulsion is continuing. Two aims are pursued by placing the effective discharge approach into the geomorphologic context of the study area. Ten zones are categorized by four distinct geomorphologic classes: meander, no islands; meander, geologic control; meander, islands and divided flow; and straight zones. One, these classes have merit for future research and are shown to be geomorphologically distinct in several ways: natural levee height and channel planform adjustment relationships, sinuosity and width to depth ratios, and bedform depth to height scaling. Two, this approach allows the comparison of the effective discharge to the study area’s geomorphology. Process-form linkages can be made between sediment transporting events and the three levels in a fluvial hierarchy: fluvial bedforms and channels, bars, and levees. Median grain size and channel position of sediment samples from these three levels were plotted on combined LiDAR and bathymetric derived cross- sections from specific geomorphologic zones. This analysis indicates that the fluvial hierarchy coincides with the stages of effective discharge but seems to scale to the elevation of natural levees. This study interjects a geomorphologic approach into the lower Mississippi River discourse and raises a number of interesting questions for further research. / text

Microbial communities influence the kinetics and pathways of reactions involved in the dissolution of a number of minerals (Ehrlich 1996). On a smaller scale these interactions can affect substrate permeability, porosity, and create highly localized biogeochemical conditions. However, a mechanistic understanding of the consequences of microbial surface colonization on calcite dissolution rate has yet to be achieved. More specifically, little is known about the impact of sulfur-oxidizing bacteria activity on the rate of carbonate mineral dissolution, or the nature of the microbe-limestone attachment and interaction. Through a series of laboratory and field experiments the effect of mineral surface colonization by microbial communities, obtained from an active sulfuric acid cave (Lower Kane Cave (LKC), Big Horn Basin, WY), on the dissolution rate of Madison Limestone was quantified. Results from laboratory experiments showed that a microbial biofilm, composed primarily of Epsilonproteobacteria and Gammaproteobacteria growing on a limestone surface oxidized thiosulfate and increased carbonate dissolution rates up to 3.3 times faster than abiotic rates. When all thiosulfate substrate was withheld the community oxidized stored intracellular sulfur, continuing to accelerate limestone dissolution and decreasing pH. This process is sensitive to O2 limitations. Characterization of this aggressive sub-biofilm corrosion was more closely examined by SEM imaging. By comparing mineral surface morphology of colonized chips to non-colonized chips of various carbonate substrates, it was shown that even under conditions near equilibrium with calcite, aggressive dissolution of carbonate substratum occurs exclusively beneath the biofilm. These findings support the hypothesis that (1) sulfur-oxidizing microbial communities aggressively dissolve carbonates in order to buffer the production of excess acidity by neutrophilic communities and (2) biofilm presence affects carbonate mineral dissolution by physically separating a bulk stream water from the sub-biomat environment. Furthermore, it was found that mineralogy affects the degree of establishment of microbial communities in this environment. Results from a series of four laboratory and one in situ reactor experiment showed that limestone and dolostone substratum consistently had higher biomass accumulations than silicate minerals or pure Iceland spar calcite in the same reactor. These results provide evidence to support the hypothesis that mineralogy influences microbial accumulation in sulfuric-acid karst systems. Particularly, neutrophilic sulfur-oxidizing communities accumulate in greater quantities on solid substrates that buffer metabolically-generated acidity. These results also demonstrated the dependence of microorganisms on colonization of a particular mineral surface, possibly in order to gain access to micronutrients bound within solid substrates when exposed to nutrient-limited conditions. / text

No description available.

Στην διατριβή αυτή έχουμε ως σκοπό την μελέτη των φυσικών και μηχανικών ιδιοτήτων του κατώτερου μαργαϊκού ορίζοντα του Νομού Αχαϊας καθως και την παράθεση των συσχετίσεων που υπάρχουν μεταξύ αυτών. / In this paper we intent to study the physical and mechanical characteristics of the lower marl horizontal of the county of Achaia. In addition we have the quotation of any connection which possibly arise among them.

Über Energie-Biomassepotenziale wird z.T. kontrovers diskutiert. Einerseits ist der Ausbau der Bioenergienutzung politisch gewollt (sowohl hierzulande als auch international), andererseits steht der Energiepflanzenanbau in direkter Konkurrenz zur Nahrungs- und Futtermittelproduktion. In der vorliegenden Arbeit wird der Frage nachgegangen, wie sich Biomassepotentiale bestimmen lassen und welche mathematischen Modellansätze es hierfür gibt. Zunächst wird die grundlegende Funktionsweise von einigen Pflanzenmodellen sowie deren Einsatz für die Biomassepotentialbestimmung erläutert und anhand eines neu entwickelten Modells, dem Modell BioSTAR, näher beschrieben. Das Modell BioSTAR ist ein kohlenstoffbasiertes Pflanzenmodell (Azam-Ali, et al., 1994) und liegt als in Java programmiertes Software-Produkt vor. Mit dem Modell lassen sich die Biomassepotentiale und der Wasserverbrauch von verschiedenen Ackerkulturen in Abhängigkeit von Klima- und Bodenfaktoren ermitteln. Das Modell ist zurzeit für vier Winterungen und drei Sommerungen validiert und wurde im Rahmen dieser Arbeit für eine Energie-Biomassepotentialanalyse für den Raum Niedersachsen herangezogen. Weiterhin wird der Frage nachgegangen, wie ein bereits hoher und nach FAO-Prognosen (FAOSTAT, 2006) weiterhin steigender globaler Fleisch- und Milchproduktkonsum zu Umweltproblematiken im Agrarbereich führt und die für die Welternährung zur Verfügung stehende Agrarfläche unnötig verknappt. Eine Reduzierung des Fleischkonsums auf die DGE (Deutsche Gesellschaft für Ernährung)-Empfehlungsmengen könnte hierzulande große Flächen freisetzen und somit dazu beitragen, die Konkurrenz zwischen dem Energiepflanzenanbau und der Nahrungs- und Futtermittelproduktion zu entschärfen.