In this study, we examined the relationship between depressive symptoms and needle-sharing behavior in a community sample of intravenous drug users (N = 499) in Baltimore, Maryland. Based on the polytomous logistic regression, higher depressive symptoms were positively associated both with needle sharing after cleaning with bleach and with needle sharing without first cleaning with bleach at the bivariate analyses. This relationship remained significant (OR = 1.66) even after adjusting for demographic characteristics, life events, drug use patterns, and social and drug networks. A significant synergistic effect of depressive symptoms and drug network on needle sharing after cleaning with bleach and needle sharing without cleaning was observed. More depressed intravenous drug users who also had a larger drug network were found to be at higher risk of needle sharing after cleaning with bleach, as well as needle sharing without cleaning (OR = 2.59). Depression status is discussed as a predisposing factor and drug network size as a precipitating factor for needle-sharing behavior. Implications for preventing needle-sharing behavior by reducing depressive symptoms are discussed.
Abstract-We present a novel computational approach to optimizing the morphological design of robots. Our framework takes as input a parameterized robot design and a motion plan consisting of trajectories for end-effectors, as well as optionally, for its body. The algorithm we propose is used to optimize design parameters, namely link lengths and the placement of actuators, while concurrently adjusting motion parameters such as joint trajectories, actuator inputs, and contact forces. Our key insight is that the complex relationship between design and motion parameters can be established via sensitivity analysis if the robot's movements are modeled as spatio-temporal solutions to optimal control problems. This relationship between form and function allows us to automatically optimize robot designs based on specifications expressed as a function of range of motion or actuator forces. We evaluate our model by computationally optimizing two simulated robots that employ linear actuators: a manipulator and a large quadruped. We further validate our framework by optimizing the design of a small quadrupedal robot and testing its performance using a hardware implementation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.