A Simple Message-Passing Algorithm for Compressed Sensing

We consider the recovery of a nonnegative vector x from measurements y = Ax, where A is an m-by-n matrix whos entries are in {0, 1}. We establish that when A corresponds to the adjacency matrix of a bipartite graph with sufficient expansion, a simple message-passing algorithm produces an estimate \hat{x} of x satisfying ||x-\hat{x}||_1 \leq O(n/k) ||x-x(k)||_1, where x(k) is the best k-sparse approximation of x. The algorithm performs O(n (log(n/k))^2 log(k)) computation in total, and the number of measurements required is m = O(k log(n/k)). In the special case when x is k-sparse, the algorithm recovers x exactly in time O(n log(n/k) log(k)). Ultimately, this work is a further step in the direction of more formally developing the broader role of message-passing algorithms in solving compressed sensing problems

Linear systems analysis program, L224(QR). Volume 1: Engineering and usage

The QR computer program is described as well as its use in classical control systems analysis and synthesis (root locus, time response, and frequency response)

Neglected Dimensions of Global Security: The Global Health Risk Framework Commission

The world has experienced global health crises ranging from novel influenzas (H5N1 and H1N1) and coronaviruses (SARS and MERS) to the Ebola and Zika viruses. In each case, governments and international organizations seemed unable to react quickly and decisively. Health crises have unmasked critical vulnerabilities— weak health systems, failures of leadership, and political overreaction and underreaction. The Global Health Risk Framework Commission, for which the National Academy of Medicine served as the secretariat, recently set out a comprehensive strategy to safeguard human and economic security from pandemic threats

Social Collaborative Retrieval

Socially-based recommendation systems have recently attracted significant interest, and a number of studies have shown that social information can dramatically improve a system's predictions of user interests. Meanwhile, there are now many potential applications that involve aspects of both recommendation and information retrieval, and the task of collaborative retrieval---a combination of these two traditional problems---has recently been introduced. Successful collaborative retrieval requires overcoming severe data sparsity, making additional sources of information, such as social graphs, particularly valuable. In this paper we propose a new model for collaborative retrieval, and show that our algorithm outperforms current state-of-the-art approaches by incorporating information from social networks. We also provide empirical analyses of the ways in which cultural interests propagate along a social graph using a real-world music dataset.Comment: 10 page

Miniature atomic magnetometer integrated with flux concentrators

High permeability magnetic flux concentrators are used to enhance the sensitivity of an atomic magnetometer operating in the spin-exchange relaxation-free regime. The magnetometer uses a millimeter scale 87Rb vapor cell and either mu-metal or Mn–Zn ferrite flux concentrators. The measured sensitivity gives excellent agreement with calculations of thermal noise from the concentrator material. The mu-metal concentrators allow a sensitivity of 50 fT Hz−1/2, limited by thermal current magnetic noise. The ferrite concentrators are limited by thermal magnetization noise at low frequencies, and reach a sensitivity of 10 fT Hz−1/2 for frequencies above 125 Hz

“What Is It That’s Going on Here?”: Community Partner Frames for Engagement

Frames—defined as mental structures built through language and symbols that categorize our thoughts and experiences—have a significant impact on partnerships, shaping how participants understand the nature of the collabo- ration. While scholars have explored how teachers might frame engagement partnerships for university students and administrators, the field has yet to deeply draw on framing theory to examine community partner frames. This article argues that framing theory can shed light on how intentional frames might foster healthier partnerships for community members, offering a ro- bust tour of framing theory and illustrating its impact through an analysis of how one community leader frames a high school-college writing partnership for local youth—ultimately suggesting that community partners may have much to teach the field of community writing about how to use frames rhe- torically in engagement contexts

Early Child Development and Maternal Labor Force Participation: Using Handedness as an Instrument

We estimate the effect of early child development on maternal labor force participation using data from teacher assessments. Mothers might react to having a poorly developing child by dropping out of the formal labor force in order to spend more time with their child, or they could potentially increase their labor supply to be able to provide the funds for better education and health resources. Which action dominates is therefore the empirical question we seek to answer in this paper. Importantly, we control for the potential endogeneity of child development by using an instrumental variables approach, uniquely exploiting exogenous variation in child development associated with child handedness. We find that having a poorly developing young child reduces the probability that a mother will participate in the labor market by about 25 percentage points.handedness, child development, maternal labor force participation