With a   growing human population, cities keep growing worldwide altering ecosystem   and thereby affecting the species living in these areas. Most studies of   urbanization and its effect on ecosystem have been conducted in the western   world and little is known about its effect in the neotropical part of the   world. I examined effects of fragment size, vegetation structure and   connectivity of urban green areas on bird species richness, mean abundance,   diversity and biomass in La Paz, Bolivia. Additionally, the effects of   different disturbance variables on bird community were evaluated. In total,   36 bird species were found in 24 fragment of varying size, connectivity and   level of disturbance. Bird species richness decreased with increasing   disturbance while connectivity and fragment size did not contribute   significantly to explain the variation in species richness at count point scale (p>0.005, multiple linear regression). At fragment   scale, however, species richness increased with fragment sizes,   which has been shown in other studies from neotrophical regions. Variation in   abundance, diversity or biomass could not be explained by connectivity,   fragment size or disturbance.     Furthermore, coverage of construction had a negative effect on species   richness while coverage of bushes and coverage of herbs were negatively   related to biomass and diversity, respectively. The composition of bird   species differed with size and disturbance of the fragments, so that more   omnivorous and granivorous species such as Zonotrichia capensis, Turdus chiguanco and Zenaida auriculata, were present in areas highly affected by human activities. Larger fragments,   less affected by human presence held a larger proportion of insectivorous   species.

Many relationship-based studies focus on how businesses are maintained and developed. However, little attention focused on individuals as business initiators and the consequent processes. This study will bridge this gap. A theoretical model with two cases will answer two questions    -How individuals initiate business through personal network? -What is the consequent process?   The studies demonstrate that individual do play a very important role when initiating a new business and they set in motion relationship-building processes that change the network structure.   The contribution for research and management is clear. The netentrepruer is a new ‘actor’ and can be useful in future studies of business networks. Management can usefully become conscious of the possibilities they have in studying their network contacts before initiating new businesses. Managers should utilize managing individual’s networks as new competition strategies. This will modify the view of management strategy and also contribute to theory building.

We study a directed network design problem called the $k$-$(S,T)$-connectivity problem; we design and analyze approximation algorithms and give hardness results. For each positive integer $k$, the minimum cost $k$-vertex connected spanning subgraph problem is a special case of the $k$-$(S,T)$-connectivity problem. We defer precise statements of the problem and of our results to the introduction. For $k=1$, we call the problem the $(S,T)$-connectivity problem. We study three variants of the problem: the standard $(S,T)$-connectivity problem, the relaxed $(S,T)$-connectivity problem, and the unrestricted $(S,T)$-connectivity problem. We give hardness results for these three variants. We design a $2$-approximation algorithm for the standard $(S,T)$-connectivity problem. We design tight approximation algorithms for the relaxed $(S,T)$-connectivity problem and one of its special cases. For any $k$, we give an $O(\log k\log n)$-approximation algorithm, where $n$ denotes the number of vertices. The approximation guarantee almost matches the best approximation guarantee known for the minimum cost $k$-vertex connected spanning subgraph problem which is $O(\log k\log\frac{n}{n-k})$ due to Nutov in 2009.

As a non-invasive method, functional MRI (fMRI) has been widely used for human brain mapping. Although many applications have been done, there are still some critical issues associated with fMRI. Perfusion-weighted fMRI (PWI) with exogenous contrast agent suffered from the problems of recirculation, which could contaminate the cerebral blood flow (CBF) estimation and make its ability of prediction "tissue-at-risk" in debate. We propose a rapid and effective method that combines matched-filter-fitting (MFF) and ICA where ICA was used for regions with a prolonged TTP and MFF was utilized for the remaining areas. The calculation of cerebral hemodynamics afterwards demonstrates that the proposed method may lead to a more accurate estimation of CBF. The extent to which CBF is reduced in relationship to normal values has been utilized as an indicator to discern ischemic injury. However, despite the well known difference in CBF between gray and white matter, relatively little attention has been given as to how CBF may be differently altered in gray and white matter during ischemia due to the inability to accurately separate gray and white matter. To this end, we propose a robust clustering method for automatic classification of perfusion compartments. The method is first to apply a robust principal component analysis to reduce dimension and then to use a mixture model of multivariate T distribution for clustering. Our results in ischemic stroke patients at the hyperacute phase show the clear advantage over the conventional technique. BOLD fMRI, as a feasible and preferred method for developmental neuroimaging, is seldom conducted in pediatric subjects and therefore the information about brain functional development in the early age is somewhat lacking. To this end, this dissertation also focuses on how functional brain connectivity may be present in pediatric subjects in a sleeping condition. We propose a statistical method to delineate frequency-dependent brain connectivity among brain activation regions, and an automatic procedure combined with spatial ICA approach to determine the brain functional connectivity. Our results suggest that functional connectivity exists as young as two weeks old for both sensorimotor and visual cortices and that functional connectivity is highly age-dependent. / Dissertation

The encrusting sponge Terpios hoshinota is a cyanobacteriosponge with symbiotic photosynthetic cyanobacteria. It covers live corals causing their death. Corals at Green Island were suspected to be infected by Terpios hoshinota in 2006, and field investigations indicated there was massive propagation of the species in both Green Island (Lyudao) and Orchid Island (Lanyu) in 2008 to 2010. We propose two hypotheses, either by Self-Seeding or by Long-Range Dispersal, that explain the fast propagation of Terpios hoshinota in the islands offshore of southeastern of Taiwan. We use ribosomal DNA and mitochondria DNA as molecular markers to investigate how the sponge disperses locally and in a greater geographic scale. A total of 110 samples, from Taiwan: Green Island, Orchid Island, and Kenting (Wanlitong). Japan: Okinawa, Nakijin, Miyako, Bise, Shiraho, Arahama Kumeshima, Yakomo (Okinoerabu), San (Takunoshima), and Xisha Island of China, were collected. Internal Transcribed Spacer 2 (ITS2) from ribosomal DNA and cytochrome oxidase I (COI) from mitochondria DNA are used as markers to infer population structure of Terpios hoshinota. No genetic variation within COI sequence over all sponges from Taiwan to Japan and China was found, although the only sponge sample from Wanlitong in Kenting had three variable sites, which suggest different species of Terpios hoshinota. Based on ITS2 analysis, haplotype diversity (h) is commonly high among most populations, but with different single haplotype found at Green Island and Arahama (Japan). Pairwise population differentiations (FST) are usually high and significant among populations supporting self-seeding, although Bise, Shiraho and Lanyu populations showed no significant differentiation that supports long-range dispersal. Analysis of Molecular Variance (AMOVA) shows no population subdivision; however, genetic differentiations among populations are significantly greater than within populations. TCS analysis indicates that single haplotype in Green Island is originated from Lanyu, and populations in Bise are widely dispersed over other sponge populations in Taiwan and Japan regions. By evidence of TCS analysis with nucleotide diversity, haplotype diversity and field investigation, Bise is the origin of Terpios hoshinota among populations within this study. Frequency of sequence haplotypes indicates one dominant haplotype is shared among most of the sponge populations, and the dominated sponge haplotype takes highest proportions of local populations. The existence of dominant haplotype may result from better dispersal or reproduction ability than other haplotype in populations. Nested clade analysis shows that populations mainly have restricted gene flow with some clade have contiguous range expansion. We suggest that populations of Terpios hoshinota propagate mainly by self-seeding method with occasional long-range dispersal event that leading to genetic connection among populations and obscuring evidence of isolation by distance in these populations. In Green Island, we consider local populations as undergoing explosion within past several years and propagate by self-seeding method coming from single lineage of Lanyu. Populations in Lanyu may come from Bise, Shiraho, and Yakomo, yet may still in status of population explosion. Populations in Japan may underwent founder effect with rapid population growth, while most populations are rarely interact with each other showing deep genetic differentiation among islands, and Bise is the origin of Terpios hoshinota in this study. Not all of the sponge individuals have ability to dominate local populations, expect for one special haplotype of Terpios hoshinota is capable of dominating local population in both range and quantity, which also has capability of spreading across islands as larger distances than its habitats range in Taiwan and Japan.

Recent efforts to optimize oil recovery from Green River reservoirs, Uinta Basin, have stimulated the need for better understanding of the reservoir connectivity at the scale of the operational unit. This study focuses on Green River reservoirs in the Wells Draw study area where oil production response to implemented waterflood is poor and a better understanding of the reservoir connectivity is required to enhance future secondary oil recovery. Correlating the sand bodies between well locations in the area remains difficult at 40-acre well spacing. Thus, interwell connectivity of the reservoirs is uncertain. Understanding the reservoir connectivity in the Wells Draw study area requires integration of all static and dynamic data for generation of probabilistic models of the reservoir at the interwell locations. The objective of this study is two-fold. The first objective was to determine reservoir connectivity at the interwell scale in the Wells Draw study area. To achieve this goal, I used well log and perforation data in the Wells Draw study area to produce probabilistic models of net-porosity for four producing intervals: (1) Castle Peak, (2) Lower Douglas Creek, (3) Upper Douglas Creek, and (4) Garden Gulch. The second objective was to find readily applicable methods for determining interwell connectivity. To achieve this goal, I used sandstone net thickness and perforation data to evaluate interwell connectivity in the Wells Draw study area. This evaluation was done to: (1) assess and visualize connectivity, (2) provide an assessment of connectivity for validating / calibrating percolation and capacitance based methods, and (3) determine flow barriers for simulation. The probabilistic models encompass the four producing intervals with a gross thickness of 1,900 ft and enable simulation assessments of different development strategies for optimization of oil recovery in the Wells Draw study area. The method developed for determining interwell connectivity in Wells Draw study area is reliable and suited to the four producing intervals. Also, this study shows that the percolation based method is reliable for determining interwell connectivity in the four producing intervals.

No description available.

A celebrated theorem of Savitch [Savitch'70] states that NSPACE(S) is contained in DSPACE(S²). In particular, Savitch gave a deterministic algorithm to solve ST-Connectivity (an NL-complete problem) using O({log}²{n}) space, implying NL (non-deterministic logspace) is contained in DSPACE({log}²{n}). While Savitch's theorem itself has not been improved in the last four decades, several graph connectivity problems are shown to lie between L and NL, providing new insights into the space-bounded complexity classes. All the connectivity problems considered in the literature so far are essentially special cases of ST-Connectivity. In this dissertation, we initiate the study of auxiliary PDAs as graph connectivity problems and define sixteen different "graph realizability problems" and study their relationships. The complexity of these connectivity problems lie between L (logspace) and P (polynomial time). ST-Realizability, the most general graph realizability problem is P-complete. 1DSTREAL(poly), the most specific graph realizability problem is L-complete. As special cases of our graph realizability problems we define two natural problems, Balanced ST-Connectivity and Positive Balanced ST-Connectivity, that lie between L and NL. We study the space complexity of SGSLOGCFL, a graph realizability problem lying between L and LOGCFL. We define generalizations of graph squaring and transitive closure, present efficient parallel algorithms for SGSLOGCFL and use the techniques of Trifonov to show that SGSLOGCFL is contained in DSPACE(lognloglogn). This implies that Balanced ST-Connectivity is contained in DSPACE(lognloglogn). We conclude with several interesting new research directions.

Interwell connectivity is a very important piece of the puzzle for petroleum engineers. To optimize the injection well flow for increasing the production rate, interwell connectivity is a very important parameter. To build a model that works with better precision and with less effort has always been desired by reservoir engineers. In this study we developed an electric circuit network model (referred as the admittance or ymodel) for calculating the admittance parameters to predict branch flow rates (injectorproducer well pair) of oil reservoirs with precision. The y-model is very simple and efficient model that can predict branch flow very efficiently. Injection and production flow rates are the key data used in this model, which also happens to be the most abundant data for oil reservoirs. Injector well bottom-hole pressure data can also be used in this model if available. The governing equation of the electric circuit analogy of well to well flow rates in the oil reservoir is based on Ohm’s law for admittance. A mathematical procedure is also being developed for this circuit network model which solves a series of equations and finds unique solutions for the admittances and branch flows. These results can further be used for predicting the production flow rate for individual producer well. The model shows very good agreement with the exploration data of real oil reservoir. / text

Previous studies have indicated that persons with autism spectrum disorder have distinct cerebella, striatum, and an impaired ability to anticipate implicit learning sequences; also, previous research indicates anatomic connections among these regions. Investigating distinctions in connectivity and impairments in the ability to anticipate implicit sequences linked to ASD would help clarify some of the core deficits associated with the disorder. This dissertation sought to explore differences in functional connectivity among the cerebellum, thalamus, and striatum. This dissertation also sought to determine if an impaired ability to anticipate implicit sequences is associated with ASD. Twelve ASD participants and 11 control participants were scanned using an MRI while engaged in a modified serial reaction task. The findings indicate that the cerebellum and the striatum are functionally connected and the thalamus mediates this connection. The results indicate that ASD participants have stronger connections than the control, and ASD participants demonstrated some impairments in learning. However, there was not enough evidence to link ASD to an impaired ability to anticipate implicit sequences. This dissertation recommends that future studies consider the roles that these distinct connections play in symptoms of ASD. / text