The effects of soil moisture, soil texture, and host orientation on the ability of Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae) to infect Galleria mellonella (Lepidoptera: Pyralidae)

Abstract Entomopathogenic nematodes (EPN) demonstrate potential as a biological control for soil dwelling insects. However, edaphic factors, such as soil moisture and texture impact the efficacy of EPN on a host. The objectives were to examine the effects of soil texture and moisture on 1) the infection rate of Galleria mellonella L. by EPN and; 2) the ability of H. bacteriophora (Poinar) to move through the soil to find a host at different orientations. Soil textures consisted of sand, a sand/silt/peat mixture, and a silt/peat mixture at 50% and 100% moisture. A general linear model was used to evaluate infection rates and EPN movement. Both soil moisture (p \u3c 0.05) and texture (p \u3c 0.05) had significant effects on nematodes infection rates of G. mellonella. Texture, moisture, and host orientation did not significantly affect (p \u3e 0.05) the ability of EPN to find a host. While EPN were able to find a host within a variety of soil types, soils that held more water had higher infection rates than soils that held less water, suggesting that moisture may be a key component in facilitating infection by EPN. By understanding the factors that influence the ability of EPN to find and infect a host, improved bio-control programs using EPN can be developed

Does correction for guessing reduce students' performance on multiple-choice examinations? Yes? No? Sometimes?

Multiple-choice (MC) examinations are becoming increasingly popular in higher education because they can be used effectively to assess breadth of knowledge in large cohorts of students. This present research investigated Psychology students' performance on, and experiences of, MC examinations with and without correction for guessing. In Study 1, data were collected from two cohorts of students across three Psychology MC examinations. The results revealed that students scored higher, and left fewer questions unanswered, when there was no correction for guessing. Furthermore, when the correction for guessing was removed from the theory MC examination, students who were told there was no correction for guessing did better than those told there was a correction. In addition, there was limited evidence of gender differences, with female students performing significantly better on one MC examination than males. In Study 2, a further set of first-year Psychology students reported their experiences of correction for guessing on open-book and closed-book MC examinations. Students reported feeling less anxious and more confident on the open-book MC examination. The findings of both of these studies have implications for instructors deciding whether or not correction for guessing is appropriate, and for the advice to be given to students preparing for MC examinations

Incentive Effects of Unemployment Insurance Savings Accounts: Evidence from Chile

This study examines the determinants of job-finding rates of unemployment benefit recipients under the Chilean program. This is a unique, innovative program that combines social insurance through a solidarity fund (SF) with self-insurance in the form of unemployment insurance savings accounts (UISAs) - so as to mitigate the moral hazard problem of traditional unemployment insurance programs. Our study is the first one to empirically investigate whether UISAs improve work incentives. We find that for beneficiaries using the SF, the pattern of job finding rates over the duration of unemployment is consistent with moral hazard effects, while for beneficiaries relying on UISAs, the pattern is free of such effects. We also find that for benefit recipient not entitled to use the SF, the amount of accumulation on the UISA does not affect the exit rate from unemployment, suggesting that such individuals internalize the costs of unemployment benefts. Our results provide strong support to the idea that UISAs can improve work incentives.Unemployment insurance;unemployment duration;savings accounts

Program for transfer research and impact studies

Research activities conducted under the program for Transfer Research and impact studies are reviewed. Programs include: Tech Brief - Technical Support Package (TSP) Program; transfer documentation; and technology transfer profiles. An analysis of user behavior patterns is made by studying questionnaires filled out by users of the Tech Brief - TSP program. The process of technology transfer is discussed in terms of improving its effectiveness

Contact-Aided Invariant Extended Kalman Filtering for Legged Robot State Estimation

This paper derives a contact-aided inertial navigation observer for a 3D bipedal robot using the theory of invariant observer design. Aided inertial navigation is fundamentally a nonlinear observer design problem; thus, current solutions are based on approximations of the system dynamics, such as an Extended Kalman Filter (EKF), which uses a system's Jacobian linearization along the current best estimate of its trajectory. On the basis of the theory of invariant observer design by Barrau and Bonnabel, and in particular, the Invariant EKF (InEKF), we show that the error dynamics of the point contact-inertial system follows a log-linear autonomous differential equation; hence, the observable state variables can be rendered convergent with a domain of attraction that is independent of the system's trajectory. Due to the log-linear form of the error dynamics, it is not necessary to perform a nonlinear observability analysis to show that when using an Inertial Measurement Unit (IMU) and contact sensors, the absolute position of the robot and a rotation about the gravity vector (yaw) are unobservable. We further augment the state of the developed InEKF with IMU biases, as the online estimation of these parameters has a crucial impact on system performance. We evaluate the convergence of the proposed system with the commonly used quaternion-based EKF observer using a Monte-Carlo simulation. In addition, our experimental evaluation using a Cassie-series bipedal robot shows that the contact-aided InEKF provides better performance in comparison with the quaternion-based EKF as a result of exploiting symmetries present in the system dynamics.Comment: Published in the proceedings of Robotics: Science and Systems 201

Hybrid Focal Stereo Networks for Pattern Analysis in Homogeneous Scenes

In this paper we address the problem of multiple camera calibration in the presence of a homogeneous scene, and without the possibility of employing calibration object based methods. The proposed solution exploits salient features present in a larger field of view, but instead of employing active vision we replace the cameras with stereo rigs featuring a long focal analysis camera, as well as a short focal registration camera. Thus, we are able to propose an accurate solution which does not require intrinsic variation models as in the case of zooming cameras. Moreover, the availability of the two views simultaneously in each rig allows for pose re-estimation between rigs as often as necessary. The algorithm has been successfully validated in an indoor setting, as well as on a difficult scene featuring a highly dense pilgrim crowd in Makkah.Comment: 13 pages, 6 figures, submitted to Machine Vision and Application

Deep space network support of the manned space flight network for Apollo, volume 2 Technical memorandum, 1969 - 1970

Deep Space Network support activities for Apollo 9 through 13 flights and associated equipmen

Anterior Hippocampus and Goal-Directed Spatial Decision Making

Contains fulltext : 115487.pdf (publisher's version ) (Open Access