Compactification of a Drinfeld Period Domain over a Finite Field

We study a certain compactification of the Drinfeld period domain over a finite field which arises naturally in the context of Drinfeld moduli spaces. Its boundary is a disjoint union of period domains of smaller rank, but these are glued together in a way that is dual to how they are glued in the compactification by projective space. This compactification is normal and singular along all boundary strata of codimension $\ge2$. We study its geometry from various angles including the projective coordinate ring with its Hilbert function, the cohomology of twisting sheaves, the dualizing sheaf, and give a modular interpretation for it. We construct a natural desingularization which is smooth projective and whose boundary is a divisor with normal crossings. We also study its quotients by certain finite groups

Ambient networks: Bridging heterogeneous network domains

Providing end-to-end communication in heterogeneous internetworking environments is a challenge. Two fundamental problems are bridging between different internetworking technologies and hiding of network complexity and differences from both applications and application developers. This paper presents abstraction and naming mechanisms that address these challenges in the Ambient Networks project. Connectivity abstractions hide the differences of heterogeneous internetworking technologies and enable applications to operate across them. A common naming framework enables end-to-end communication across otherwise independent internetworks and supports advanced networking capabilities, such as indirection or delegation, through dynamic bindings between named entities

Reconstructing Coastal Forest Retreat and Marsh Migration Response to Historical Sea Level Rise

Climate change assessments predict that rates of relative sea level rise will increase in the future, leading to enhanced inundation of low-lying coastal regions and a 20 – 50 % decline in salt marsh area by 2100. Global sea level rise began accelerating in the late 19th to early 20th century, and local rates along the U.S. mid-Atlantic coast are twice as fast as global estimates. Frequent flooding and salt stress associated with sea level rise lead to coastal transgression, and the survival of ecosystems depends on their ability to migrate inland faster than they erode and submerge. Here, I compared aerial imagery analyses and field measurements to test the hypothesis that marsh migration into retreating terrestrial forests is fundamentally tied to sea level rise, and that sea level rise does not necessarily lead to overall habitat loss. For my first chapter, I compared the areal salt marsh extent between historical topographic maps and modern aerial imageries across the entire Chesapeake Bay, and found that marsh migration into terrestrial forests largely compensated for marsh erosion at the seaward edge during the last century. This emphasizes that the location of coastal ecosystems changes rapidly on centennial timescales, and that sea level rise does not necessarily lead to overall habitat loss. For my second chapter, I reconstructed the position of coastal treelines through time at five study sites along the U.S. mid-Atlantic coast to identify long- and short- term drivers of coastal forest retreat. My findings suggest that 20th century migration rates greatly exceed pre-industrial rates (\u3c 1875 CE), and have generally accelerated throughout the last century in parallel with accelerating rates of relative sea level rise. Previous work predicts widespread marsh loss as a response to sea level rise, but underestimates the potential for marshes to migrate inland. Although anthropogenic barriers may locally prevent marsh migration into retreating coastal forests, my work finds that about 400 km2 (100,000 acres) of uplands have converted to marshes in the Chesapeake region since the late 1800s, and that this process was responsible for the formation of about 1/3 of all marsh area. Beyond the Chesapeake, my work reveals that forest retreat is fundamentally tied to the rate of sea level rise, and is accelerating through time. Therefore, management efforts that allow marshes to migrate into adjacent uplands may help preserve marshes by exploiting their ability to quickly adapt to environmental change

Names, addresses and identities in ambient networks

Ambient Networks interconnect independent realms that may use different local network technologies and may belong to different administrative or legal entities. At the core of these advanced internetworking concepts is a flexible naming architecture based on dynamic indirections between names, addresses and identities. This paper gives an overview of the connectivity abstractions of Ambient Networks and then describes its naming architecture in detail, comparing and contrasting them to other related next-generation network architectures

What's At Stake: Sequestering Meals on Wheels Could Cost the Nation $489 Million per Year

Sequestering Meals on Wheels funds could cost taxpayers far more than it saves. While across-the-board spending cuts that began March 1, called sequestration, are expected to reduce spending on Meals on Wheels programs this year by an estimated $10 million, these savings will be dwarfed by at least$489 million per year in increased spending on Medicaid, both this year and in each subsequent year that sequestration remains in place.Outside of Washington, waiting lists for Meals on Wheels enrollees have received media attention, but the expected savings have remained largely unquestioned. In reality, cutting Meals on Wheels will very likely increase the federal deficit by increasing the overall cost burden and shifting it to Medicaid, local charities, and other programs.Overall, Meals on Wheels saves the federal taxpayers money by helping participants live at home instead of living in comparatively expensive nursing homes. The average cost to Medicaid of nursing home care per patient is approximately $57,878 annually.By contrast, the cost to Medicaid of home care is much lower, approximately$15,371 annually, or $42,507 less than nursing home care. Nationally, according to a survey by the Administration on Aging, as many as "92$479 million dollars over the seven months it will be implemented during this federal fiscal year, which ends September 30 (see the appendix for details of this estimate). Moreover, because sequestration-related cuts are expected to increase in FY 2014 and beyond, if sequestration is not reversed, Medicaid-related costs will increase even more in those years