Agricultural grasslands have replaced native Midwestern prairies in the form of pasture, idle cropland and conservation fields. The condition of these cover types directly and indirectly influences the distribution, variety and productivity of avian populations within these landscapes. CP33 habitat buffers are an incentive-based conservation practice specifically designed to increase upland bird habitat and productivity. Landowners are encouraged to remove row crops from production and return them to early successional grassland habitat along the margin of agricultural fields. However, buffers exhibit a high perimeter-to-area ratio, which may increase negative edge effects, thereby creating sink populations. During the 2013 and 2014 breeding seasons, I assessed grassland bird response to CP33 habitat buffers in southern Illinois. Focal species included the northern bobwhite (Colinus virginianus), dickcissel (Spiza americana), eastern meadowlark (Sturnella magna), field sparrow (Spizella pusilla), indigo bunting (Passerina cyanea), and red-winged blackbird (Agelaius phoeniceus). I used a hierarchical multiscale framework to examine the influence of habitat variables at multiple scales on avian abundance, species richness, and occupancy. I also used this same framework, and logistic exposure modeling, to examine daily survival rates of nests found within CP33 habitat buffers. Multiscale occupancy and logistic exposure models consistently performed better than single-scale models for focal bird species; however, relative importance of local variables and landscape variables differed considerably among focal species. Nest survival rate was not strongly affected by edge effects or edge type. Microhabitat variables were much more influential in predicting nest survival. In my study area, CP33 habitat buffers are unlikely to support source populations for most of the focal grassland bird species I studied. To increase nest survival rates within established CP33 habitat buffers, managers should focus on microhabitat vegetation characteristics. To increase bird occupancy of CP33 habitat buffers in southern Illinois, managers should increase the size of CP33 habitat buffers within a landscape having adequate grassland cover. However, managers should not consider CP33 habitat buffers a panacea for most grassland avian species.

The effectiveness of giant cane [Arundinaria gigantea(Walt.) Muhl.] as riparian buffer vegetation has been demonstrated through research and has gained interest from state and federal agencies to support restoration efforts. Unfortunately, little is known about the physical and chemical properties of the soils below canebrakes and how soil characteristics influence aboveground and belowground biomass production. To determine what physical attributes of the plant influence its success as riparian buffer vegetation and also to determine the interactions with underlying soils, fourteen canebrakes were sampled throughout Southern Illinois. Objective one was to develop an allometric equation to quantify belowground biomass based on aboveground parameters of canebrakes. Previous research found that successful propagation was dependent on rhizome length, the number of internodes and the number of rhizome buds present, but no data exists regarding the yield of rhizomes for a given area. By harvesting all aboveground biomass (culms and leaves) and belowground biomass (roots and rhizomes) to a depth of 25 cm from a 1-m2 plot at each site, morphometric characteristics were quantified and biomass allocation throughout the plant was determined. A significant linear relationship between total aboveground biomass (live and dead) and belowground biomass in giant cane was evident (R=0.865, p<0.001). Although this is a strong relationship, it may be impractical for a manager to harvest, process, and weigh all of the aboveground biomass to speculate the biomass below ground. Therefore, metrics were explored for predicting the length of rhizome, number of rhizome internodes and number of rhizome buds an area will yield using multiple regression and models were developed that estimate these parameters. Using the equation that predicts the number of rhizome buds for a given area, the yield of propagules can then be estimated. Although this equation does not account for all variation of belowground characteristics, it will provide a general guideline for land managers restoring giant cane. The second objective was to estimate biomass allocation of giant cane roots/rhizomes beneath canebrakes by depth (i.e., at 25-cm increments to a depth of 150 cm). Results showed that 67% of giant cane's belowground biomass was within the top 25 cm of the soil profile and accounted for 65% of all belowground biomass encountered at that depth. Giant cane rhizomes were documented to a depth of 51-75 cm deep while cane roots existed in the deepest cores at a depth of 126-150 cm with an average density of 0.08 kg m-3. Giant cane belowground biomass declined with increasing depth, but was still the dominant species at 26-50 cm, comprising 61% of all biomass encountered at that depth. These results support the utility of giant cane as an effective riparian buffer species by increasing the soil porosity and promoting infiltration while contributing a significant source of carbon to the soil profile. Chemical and physical soil properties were measured to determine if they related to canebrake characteristics. Significant correlations were found between various soil properties and canebrake characteristics, implying there is an interaction between giant cane and the underlying soil. Results from this research will improve our understanding of the dynamics of giant cane and supplement existing information to help guide restoration efforts.

Cultivation of a model cyanobacterium Synechocystis PCC 6803 under low light conditions in the presence of glucose and TES buffer leads to a change of the medium color from colorless to yellow. The absorption spectrum of the excreted unknown compound indicated a possible relationship to plant chlorophyll degradation products. To confirm this speculation the compound was purified by a combination of solid phase extraction and HPLC. The mass and NMR characteristics excluded its close relationship to modified tetrapyrroles, nevertheless the precise structure could not be determined by these means due to a complicated nature of the compound and its high polarity.

As intrusion attacks on systems become more and more complex, the tools trying to stop these attacks must follow. This thesis has developed a testbed to test and evaluated three freely available protection tools for the GNU/Linux platform to see how they fare against attacks.

The area of investigation for this study falls within a small urban island called Westbury. Situated 7km to the West of Johannesburg’s CBD, it is isolated from the adjacent urban fabric as a result of its historical and also recent development. Westbury itself also consists of a series of fragmented islands with undefined boundaries, weak urban blocks and a disorientated grid. The area has recently been identified as a high priority region for densification1 by the city of Johannesburg, supported by transport-oriented infra-structural investment. The questions raised by this study are contextualized against this backdrop. How could densification in Westbury be achieved towards the creation of a more inter-connected, cohesive, accessible and therefore sustainable urban environment? Following from this: How could Westbury be better integrated with the immediate surrounding urban fabric whilst combating its own fragmentation? What is the role of urban blocks and boundary conditions to help shape a future more integrated Westbury, and also towards meaningful place-making? In what ways can architecture contribute in order to improve the urban fabric that operates on various scales: from the very scale of the house to that of an urban boundary to that of the urban block and ultimately the greater urban network? The hypothesis outlined in this study is that architecture is too weak to stand in isolation, that a network of buildings is necessary to achieve a more sustainable, accessible, cohesive, and inter-connected urban environment. This is tested through a rigorous analysis of boundary conditions at different scales as reflected in the urban blocks of Westbury and the resultant architectural strategies. Finally, a block and its attendant boundaries is singled out to test the architectural contribution towards densification of the suburb, the making of place, and better inter-connectivity. The process is envisaged as driven from both the scale at which urban issues inform the architecture, and the reverse scale the architecture in Westbury informs the urban master plan. The architecture in style and scale sets the conditions for the proposed urban blocks. The boundary wall being the medium where urban meets architecture. “For these dreams to flourish in reality, we must recognise that there can be no ready-made solutions in housing, no recipes or / Mini Dissertation (MArch (Prof))--University of Pretoria, 2018. / Architecture / MArch (Prof) / Unrestricted

Buffer sizing is an important network configuration parameter that impacts the quality of data traffic. Falling memory cost and the fallacy that ‘more is better’ lead to over provisioning network devices with large buffers. Over-buffering or the so called ‘bufferbloat’ phenomenon creates excessive end-to-end delay in today’s networks. On the other hand, under-buffering results in frequent packet loss and subsequent under-utilization of network resources. The buffer sizing problem has been studied extensively for wired networks. However, there is little work addressing the unique challenges of wireless environment. In this dissertation, we discuss buffer sizing challenges in wireless networks, classify the state-of-the-art solutions, and propose two novel buffer sizing schemes. The first scheme targets buffer sizing in wireless multi-hop networks where the radio spectral resource is shared among a set of con- tending nodes. Hence, it sizes the buffer collectively and distributes it over a set of interfering devices. The second buffer sizing scheme is designed to cope up with recent Wi-Fi enhancements. It adapts the buffer size based on measured link characteristics and network load. Also, it enforces limits on the buffer size to maximize frame aggregation benefits. Both mechanisms are evaluated using simulation as well as testbed implementation over half-duplex and full-duplex wireless networks. Experimental evaluation shows that our proposal reduces latency by an order of magnitude.

N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) has been shown to cause changes in cultured endothelial cells and smooth muscle function at concentrations from 5 to 25 mM. To determine whether HEPES also affects vascular permeability, the effects of two buffers, HEPES and phosphate, were compared in isolated perfused rabbit lungs. Hemodynamic parameters and vascular protein permeability-surface area products (PS) were measured after perfusion with the buffers. Endothelial permeability was measured for an anionic and a cationic albumin to assess the charge effects of the zwitterion buffer. With HEPES, there were no changes in vascular pressure or resistance but permeability was affected. Cationic albumin permeability increased with 12 mM HEPES (8.7(phosphate) → 30(12 mM HEPES) x ml · min-1 · g dry lung-1 x 10-2) as did the anionic albumin PS (2.7(phosphate) → 3.52(12 mM HEPES). The cationic PS returned to baseline (8.1(60 mM HEPES)) at 60 mM HEPES, but the anionic PS did not change from the 12 mM HEPES (4.01(60 mM HEPES)). In summary, we find that HEPES is not innocuous. Although hemodynamic parameters did not change, endothelial permeability was increased when HEPES was used at normal concentrations. Therefore, HEPES should be used with caution as a physiological buffer in perfused organ systems.

With population growing every year, more and more people are looking for places to live. This can lead to construction of houses near and around landfills. As homes get closer to landfills, the odors these landfills produce become more of a problem, and lead to an increase in odor complaints. Modeling these odors and recommending odor buffer distances will help determine limits on how close to landfills new homes should be allowed. This should help reduce future odor complaints. To solve this problem one must accurately estimate odorous gas emissions from the landfill. Often odors can be indicated by methane emissions. A new technique using hundreds of ambient VOC concentrations, which are taken from landfills on a quarterly basis, was used to invert and solve the Gaussian dispersion equation for methane emissions. In this technique, Voronoi diagram theory was used to automatically locate numerous point sources for optimal positioning relative to receptors. The newly solved methane emission rates can now be input into a dispersion model, and the resulting methane concentrations used as surrogates for odors around the landfill. One of the most important steps in the analysis is to determine which model is best to use for odor modeling. There are many considerations that go into this decision, such as how much time it takes to run the model, how accurate the model is, and how easy the model is to use. Two current models CALPUFF and AERMOD were compared. In the modeling, methane was used as a surrogate for the odors. Since landfills handle many different combinations of waste, the type of odor may vary from landfill to landfill. In this test case, H2S was assumed to be the main contributor to the odor emitted from the landfill, and the H2S-to-methane ratio was used to estimate downwind H2S concentrations from the modeled methane concentrations. Once an air dispersion model is selected, it can be used to model odors and to develop a graphical screening method to show where these odors are most likely to occur and how strong they will be. This can be used to determine how close to a landfill homes can be built without having significant odor impacts bothering these new residents. Also, this tool can be used for improving landfill gas management. Several example scenarios include the possibility of not enough soil cover placed on the waste, leaks from an aging collection system, or cracks in the collection piping created by the settling of waste.

A Network Interface Card (NIC) is used for receiving the packets, processing the packets, passing the packets to the host processor, and sending the packets to other computers in a network. NIC uses the buffer management algorithm to distribute the buffer space among different applications. An application may use User Datagram Protocol (UDP) or Transmission Control Protocol (TCP), depending upon the type of application. Buffer Management Algorithm for UDP-based applications may be completely different from the one for TCP applications, since in UDP- based applications receiver do not send acknowledgement back to the sender. This thesis proposes two buffer management algorithms: 1) Fairly Shared Dynamic Algorithm (FSDA) for UDP-based applications; 2) Evenly Based Dynamic Algorithm (EBDA) for both UDP and TCP-based applications. FSDA utilizes full buffer memory and reduces the packet losses significantly. EBDA reduces packet losses by taking the packet size factor in summation rather than multiplication. This also helps in maintaining fairness among different applications. For the average network traffic load, the FSDA algorithm improves the packet loss ratio by 18.5 % over the dynamic algorithm and by 13.5% over the DADT, while EBDA improves by 16.7 % over the dynamic algorithm and by 11.8% over the DADT. For the heavy network traffic load, the FSDA algorithm improves the packet loss ratio by 16.8 % over the dynamic algorithm and by 12.5% over the DADT while EBDA improves the packet loss ratio by 16.8 % over the dynamic algorithm and by 12.6% over the DADT. For the actual traffic load, the improvement over DA and DADT is 13.6% and 7.5% for FSDA and 7.6% and 1.9% for EBDA.

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