UCLA

We report on results from triaxial drained monotonic and cyclic compression tests for four different aggregates (gabbro, limestone, demolished concrete, steel slag), and discuss the applicability of UBCSAND model for simulating the relevant non-linear stress-strain curves. First, UBCSAND is integrated analytically for the elastic and plastic volumetric and deviatoric strains, leading to a pair of novel closed-form solutions expressed in terms of hypergeometric functions. These solutions are inherently free of numerical errors and can be used for the evaluation of results from numerical integration. Second, three calibration techniques for the model parameters are presented and compared: (1) a graphical “chart” solution based on results from forward numerical simulations; (2) a numerical approach based on minimization of residuals; and (3) an informed trial-and-error approach based on the analytical solution. Errors in numerical integration of the model are explored by comparing the analytical solution against results from an Euler integration. Variations in the calibrated parameters are discussed for drained monotonic and cyclic triaxial loading considering different types of aggregates.

Clustered outbreaks of multi-drug resistant (MDR) Shigella are on the rise among men who have sex with men (MSM). Identification of MDR sub-lineages is critical for clinical management and public health interventions. Here, we describe a novel MDR sub-lineage of Shigella flexneri isolated from an MSM patient without a travel history in Southern California. Detailed genomic characterization of this novel strain would serve as a reference to aid monitoring and future outbreak investigation of MDR Shigella among MSM.

Community health workers (CHW) can play an active role in providing integrated HIV and harm reduction services. We used social media to create a virtual network among Vietnamese CHW. This paper reports CHW's social media engagement and the relationships with other work-related indicators. Sixty CHW participated in an intervention for integrated HIV/drug use service delivery. Following two in-person sessions, Facebook groups were established for CHW to share information, seek consultation, and refer patients. CHW's levels of online engagements were tracked for six months and linked to their service provision confidence, interaction with patients and other providers, and job satisfaction. The CHW made 181 posts, which received 557 comments and 1,607 reactions during the six months. Among the 60 CHW, 22 (36.6%) had three or more posts, 19 (31.7%) had one or two posts, and 19 (31.7%) had no post. Comparing the baseline and 6-month follow-up data, we observed that those who posted three or more times showed better service provision confidence (p = 0.0081), more interaction with providers in other settings (p = 0.0071), and higher job satisfaction (p = 0.0268). Our study suggests using social media to engage CHW in virtual communications to improve service provision in communities.

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Implications for school health policy, practice, and equity

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The purpose of this work is to study machine-learning-based model predictive control of nonlinear systems with time-delays. The proposed approach involves initially building a machine learning model (i.e., Long Short Term Memory (LSTM)) to capture the process dynamics in the absence of time delays. Then, an LSTM-based model predictive controller (MPC) is designed to stabilize the nonlinear system without time delays. Closed-loop stability results are then presented, establishing robustness of this LSTM-based MPC towards small time-delays in the states. To handle input delays, we design an LSTM-based MPC with an LSTM-based predictor that compensates for the effect of input delays. The predictor is used to predict future states using the process measurement, and then the predicted states are used to initialize the LSTM-based MPC. Stabilization of the time-delay system with both state and input delays around the steady state is achieved through the featured design. The approach is applied to a chemical process example, and its performance and robustness properties are evaluated via simulations.

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This article explores the making of an expansive and expanding economic imagination in disparate Occupy sites—the Alternative Banking working group of Occupy Wall Street, the daily life of lists in Liberty Square, née Zuccotti Park, and the work of Strike Debt. In particular, I focus on transformative possibility in unanticipated places. Where anthropology and critical theory have often sought out capitalism’s otherwises for inspiration and potential, the expansion of the economic imagination I trace here suggests that the centers constitute zones of possibility as well. I aim to show not only the conditions of possibility for a certain kind of imaginative work in the dense and seemingly definitive spaces of financial expertise but also a remarkable, and largely unrecognized, contemporary conversation around the future of banking, foreclosures, and democratized finance.