Practical and Innovative: A Design for a New Field Nursery at the Morris Arboretum

The Morris Arboretum is an exceptionally beautiful place to learn about and appreciate trees from around the world. Before these incredible specimens make their way out to the garden, many of these plants will spend at least part of their life in the field nursery. Unlike commercial nurseries where large quantities of relatively few species are grown, the field nursery at the Morris Arboretum serves a more dynamic role hosting a wide array of tree and shrub species from all over the world. The purpose of the nursery at the Arboretum is threefold: to offer a more hospitable growing environment for plants that do not grow well in pots; to provide a space for trees to grow larger in size before being planted out; and to test the hardiness of a tree species. Some of the important considerations in designing a new field nursery are location, spacing, irrigation, weed control, fertilization, fencing, and shade structure. Given these considerations, a new nursery will be designed to minimize maintenance and environmental impact while at the same time creating an optimal environment for the young plants of the Morris Arboretum to thrive until they reach their ultimate destination in the landscape

Precision stationkeeping with azimuthing thrusters

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references.Precision positioning of an unmanned surface vehicle (USV) in a nautical environment is a difficult task. With a dual azimuthing thruster scheme, the optimization of thruster outputs uses an online method to minimize the amount of error. It simplifies necessary calculations by the assumption that the rotating thrusters are always parallel thus making the system holonomic. The scheme accommodates for limitations in actuator outputs, including rotation limits and time-lagged thrusts and was implemented in a MATLAB simulation that tested its response to step errors and disturbance forces, similar to what it would encounter in actual implementation. It successfully achieved commanded outputs in all three degrees of freedom, typically within 25 seconds. It also rejects constant and sinusoidal disturbance forces. However, specific configurations arise where the USV, at times, is uncontrollable and the system only recovers after being further perturbed into a controllable configuration.by Adam D. Doroski.S.B

Integrity Verification for SCADA Devices Using Bloom Filters and Deep Packet Inspection

In the past, SCADA networks were made secure through undocumented, proprietary protocols and isolation from other networks. Today, modern information technology (IT) solutions have provided a means to enhance remote access through use of the Internet. Unfortunately, opening SCADA networks to the Internet has provided routes of attack. Cyber attacks on these networks are becoming more common and can inflict considerable damage to critical infrastructure systems. Furthermore, devices on these networks can be infected with malware that causes them to falsify their responses to operators, concealing alternate operation or hiding alarm conditions. Considering their applications, securing these networks translates to improved physical security in the real world. Since modern IT solutions are impractical to deploy in the resource constrained SCADA networks, other solutions must be researched. This research evaluates an integrity verification system implemented on a Xilinx ML507 development board called the SIEVE system. The design incorporates Bloom filters and SCADA-specific intrusion detection techniques to speed identification of invalid commands and current sensing to investigate whether or not a device correctly carried out a given command. Results show that the SIEVE system is able to inspect and correctly identify 100% of network traffic at a 200 command per second frequency. Correct identification of valid MODBUS/TCP traffic begins to fail at 350 commands per second, introducing false positives. Tests of the Bloom filters show that they reduce the time necessary to process and log invalid MODBUS/TCP commands by 4.5% to 2328.06% depending on the number of operations performed by the command

Stand Dynamics and Diversity Patterns in Planted and Naturally Regenerating Urban Forests

The world is becoming an increasingly urban planet with 68% of the global population expected to live in cities by 2050 and urban land cover expected to increase by 40%. This urban expansion brings with it a host of environmental and health consequences such as the urban heat island effect, reduced air and water quality, and biodiversity losses. In forested biomes, trees and forests growing within the urban matrix offer a valuable opportunity to offset many of these negative impacts and to provide a suite of additional benefits. In recognition of this opportunity, there is mounting interest in investing in urban forests as a form of green infrastructure. Effectively directing these investments will depend on baseline knowledge of current and potential future conditions, however, urban forest dynamics are poorly understood. In this dissertation, I help to overcome knowledge gaps in urban forest dynamics by examining patterns of nativity, diversity, and species composition in planted and naturally regenerating urban forests. To do this, I draw from two datasets that capture the two sources of future trees in urban settings: natural regeneration and tree planting.In my first two chapters, I use field data from forested natural areas throughout the city of New Haven, CT, USA to examine successional trajectories and regeneration potential in urban forest patches. While previous work has focused on discerning the differences between urban and rural forests, in this work, I focus instead on discerning the range of urban forest types that can be found within a single city. Using patch size as a framework I examine naturally regenerating forests in large (95-126 ha), medium (1-19 ha), and small forest patches (0.05-0.65 ha). In my first chapter, I find that forest structure, composition, and the proportion of native species shifts significantly with forest patch size and by relating these shifts to regeneration patterns in the seedling layer I highlight a suite of distinct successional trajectories. In my second chapter, I build on these findings by examining the regeneration potential of the buried seedbank at these same plots. Similar to findings from my first chapter, I find that the proportion of native species and dominance of individual tree species in the buried seedbank shifts with forest patch size. Together, these two chapters suggest that large patches are following similar successional trajectories to analogous rural forests in the region whereas small patches are exhibiting more distinct and novel successional trajectories. Medium patches are the most challenging patch size to characterize and in some cases resemble large patches and in other instances, small patches. Challenges in distinguishing forests in this patch size highlight the potentially important role that landscape structure, age, land-use history, and anthropogenic impacts – in addition to patch size – play in shaping urban forest dynamics. Indeed, results from regeneration regressions in these two chapters indicate that proximity to surrounding forest cover is a significant positive predictor of the number of native seedlings and germinants in the buried seedbank. This finding suggests that native tree planting may be necessary in more isolated forest patches in order to sustain future cohorts of native trees. Tree planting is the focus of my third chapter. In this chapter, I use survey data from municipalities and non-profit organizations throughout the Northeastern USA to understand how local tree planting programs contribute to regional diversity patterns. I find that cities in the Northeast rely heavily on a narrow suite of species and genera for specific ecosystem services. Specifically, nearly 20% of all shade trees planted in the region are oak species and over 50% of ornamental trees are either cherry species or tree lilac. This overreliance on individual taxa may have implications for future forest resilience. Moreover, tree planting palettes in the region included invasive tree species, one of which (Norway maple) was also a prolific species regenerating in the urban forest patches from chapters one and two. This finding underscores the importance of considering natural regeneration and tree planting in the context of one another as planted trees may serve as seed sources for naturally regenerating trees in natural areas. Collectively, this dissertation illuminates potential future forest conditions in planted and naturally regenerating urban forests. Insights into the future forest are the cornerstone to effective and appropriate forest management and findings from this dissertation can be leveraged to inform management in urban forests throughout the Northeastern, USA. Beyond management, this dissertation also introduces frameworks that can be further honed and developed to enhance our understanding of forest dynamics in urban areas around the world

Leveraging Community Support to De-vine New Haven’s Natural Areas

This case study discusses the Urban Resources Initiative’s efforts to remove invasive vines from natural areas in New Haven, CT. The Urban Resources Initiative (URI) is the primary urban forestry organization in New Haven, and community engagement is a key feature of their programming. Working with a combination of local stewardship groups (“Community Greenspace”) and a workforce program (“GreenSkills”) for previously incarcerated individuals and teens, URI began hosting vine removal workdays in New Haven’s parks as a way to both protect critical components of the city’s forest canopy and build interest and investment in the city’s natural areas

Examining When Life Begins by Explaining Fission and Fusion in the Human Organism

The question of when human life begins is critical in debates related to life issues. While there are a variety of proposals as to how an organism should be defined, many biologists and ethicists, particularly Catholics, have approached this issue by arguing that fertilization defines the beginning of a new organism. Examining the processes of fission and fusion, which take place before gastrulation, provides strong evidence for when human life beings and therefore how it should be defined. Among the four dominant theories, regulative fission and fusion are the best explanations in terms of being the most consistent with the biological data. This explanation of twinning provides compelling evidence that fertilization is not a necessary condition for human generation, although it may be a sufficient condition. While fertilization generates the vast majority of human beings, additional human beings may rarely be generated during fission events

Efekat prelaska sa konvencionalne na konzervacijsku obradu i setvu pšenice, soje, stočnog graška i pasulja

These paper presents and analyzes the results achieved in assays of production wheat, soybean, bean, which is set to determine exploitation, energy and environmental effects of land use conservation tillage and direct seeding. The work will be displayed along side conventional and conservation planting these cultures of working hours,fuel, yield, comparative two different conceptions of cultivation and sowing.U radu se prezentuje i analizira ostvareni rezultati na ogledima pšenice, soje, pasulja koji je postavljen radi utvrđivanja eksploatacionih, energetskih i ekoloških efekata u primeni konzervacijske obrade zemljišta direktne setve. U radu će se prikazati uporedo konvencionalna i konzervacijska setva navedenih kultura i analiza utroška radnih sati, goriva, prinosa, uporedne radne operacije dve različite koncepcije obrade zemljišta i setve

Palladium-catalyzed heteroallylation of unactivated alkenes – synthesis of citalopram

A palladium-catalyzed difunctionalization of unactivated alkenes with tethered nucleophiles is reported. The versatile reaction occurs with simple allylic halides and can be carried out under air. The methodology provides rapid access to a wide array of desirable heterocyclic targets, as illustrated by a concise synthesis of the widely prescribed antidepressant citalopram

Engineering tendon and ligament tissues : present developments towards successful clinical products

Musculoskeletal diseases are one of the leading causes of disability worldwide. Among them, tendon and ligament injuries represent an important aspect to consider in both athletes and active working people. Tendon and ligament damage is an important cause of joint instability, and progresses into early onset of osteoarthritis, pain, disability and eventually the need for joint replacement surgery. The social and economical burden associated with these medical conditions presents a compelling argument for greater understanding and expanding research on this issue. The particular physiology of tendons and ligaments (avascular, hypocellular and overall structural mechanical features) makes it difficult for currently available treatments to reach a complete and long-term functional repair of the damaged tissue, especially when complete tear occurs. Despite the effort, the treatmentmodalities for tendon and ligament are suboptimal, which have led to the development of alternative therapies, such as the delivery of growth factors, development of engineered scaffolds or the application of stem cells, which have been approached in this review