Multicommodity Multicast, Wireless and Fast

We study rumor spreading in graphs, specifically multicommodity multicast problem under the wireless model: given source-destination pairs in the graph, one needs to find the fastest schedule to transfer information from each source to the corresponding destination. Under the wireless model, nodes can transmit to any subset of their neighbors in synchronous time steps, as long as they either transmit or receive from at most one transmitter during the same time step. We improve approximation ratio for this problem from O~(n^(2/3)) to O~(n^((1/2) + epsilon)) on n-node graphs. We also design an algorithm that satisfies p given demand pairs in O(OPT + p) steps, where OPT is the length of an optimal schedule, by reducing it to the well-studied packet routing problem. In the case where underlying graph is an n-node tree, we improve the previously best-known approximation ratio of O((log n)/(log log n)) to 3. One consequence of our proof is a simple constructive rule for optimal broadcasting in a tree under a widely studied telephone model

Drier Conditions, More Wildfire, and Heightened Concerns About Forest Management in Eastern Oregon

This brief examines climate change and forest conditions in eastern Oregon. Eastern Oregon is experiencing warmer, drier conditions and increased numbers of wildfires. Surveys of the Oregon public find that forest health and wildfire threats are widely shared concerns. The more knowledgeable residents say they are about forest management, the more likely they are to say that forests are becoming less healthy. Majorities support active forest management (forest thinning, surface fuel reduction) and restoration to reduce the likelihood of high-severity wildfires that would damage forest resources and threaten local communities. The authors conclude that forests continue to be an important part of the heritage of western lands, and their management is a crucial issue of our time. Engaging private forest owners who are not actively managing their lands and developing new partnerships to support active management on public lands are essential to addressing the threats confronting the Blue Mountains and the Inland Northwest

The Capacity of Smartphone Peer-To-Peer Networks

We study three capacity problems in the mobile telephone model, a network abstraction that models the peer-to-peer communication capabilities implemented in most commodity smartphone operating systems. The capacity of a network expresses how much sustained throughput can be maintained for a set of communication demands, and is therefore a fundamental bound on the usefulness of a network. Because of this importance, wireless network capacity has been active area of research for the last two decades. The three capacity problems that we study differ in the structure of the communication demands. The first problem is pairwise capacity, where the demands are (source, destination) pairs. Pairwise capacity is one of the most classical definitions, as it was analyzed in the seminal paper of Gupta and Kumar on wireless network capacity. The second problem we study is broadcast capacity, in which a single source must deliver packets to all other nodes in the network. Finally, we turn our attention to all-to-all capacity, in which all nodes must deliver packets to all other nodes. In all three of these problems we characterize the optimal achievable throughput for any given network, and design algorithms which asymptotically match this performance. We also study these problems in networks generated randomly by a process introduced by Gupta and Kumar, and fully characterize their achievable throughput. Interestingly, the techniques that we develop for all-to-all capacity also allow us to design a one-shot gossip algorithm that runs within a polylogarithmic factor of optimal in every graph. This largely resolves an open question from previous work on the one-shot gossip problem in this model

Building the Blue Economy: Opportunities for Community-Based Organizations in Stormwater Management

The United States has a serious problem with combined sewer overflows. In responding to this environmental and public health menace, many regions are using innovative “green infrastructure” or “blue economy” approaches in addition to traditional “gray infrastructure” such as pipes and reservoirs. These new methods offer many environmental benefits and cost efficiencies and can be a potent source of jobs – including entry level jobs. This report outlines ways for community-based organizations to seize these opportunities, both by advocating for green infrastructure and by developing social enterprises that do stormwater management work at a neighborhood level. It is designed for non-profit groups, policy makers, and funders interested in the intersection of sustainability, neighborhood redevelopment, and job creation and the possibility of a triple win in all three areas