What are the Physical Health Benefits of Urban Tree Canopy in the Springfield, Massachusetts Neighborhoods?

This thesis explores the relationship between urban tree canopy and physical health measures between different Springfield, Massachusetts neighborhoods. The study hypothesis was that there would be a correlation between urban tree canopy and human health. Statistical analysis was used to examine the correlation between available health data and urban trees. The existing neighborhood health data that was available comprised of asthma rate, infant mortality, and low birth weight. It also examined other data such as median household income, demographic percentages, home ownership, and green space. The research questions guiding this study were: Are there any correlations between urban trees canopy and the asthma rates, infant mortality rates, and low birth weight in Springfield neighborhoods? Do local residents have equal access to resources such as urban tree canopy and green space? Previous research reviewed in the literature shows that urban tree canopy provides social, environmental, physical benefits to their surroundings and to the residents of urban neighborhoods, such as those in Springfield. The literature review also discussed some challenges with regard to unequal access to urban trees in other cities, such as Boston that show environmental justice issue may be an influence. The current study used data on health, demographic, and urban tree canopy data that was primarily collected by the Pioneer Valley Planning Commission, the US Forest Service and ReGreen Springfield. The major findings showed correlations between urban tree canopy and median household income, low birth weight, and demographics percentages. Those correlations indicated that there are signs of environmental justice issues in the City of Springfield. This correlation results verifies prior that was reviewed in the literature. One recommendation to offset the issues of environmental justice would be to invest in organization such as ReGreen Springfield and other organizations that promote planting trees by neighborhood groups

Two degree-of-freedom hopping robot with parallel architecture using linear Lorentz-force actuators

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 38).This thesis presents the design and fabrication of a 2-DOF robotic leg using linear Lorentz-force actuators arranged in a parallel configuration. The decision to use linear actuators, a parallel architecture, and Lorentz-force motors was made because of distinct differences between these designs and the alternatives, notably, their lower weight, better resolution, and high bandwidth. We have shown that a robot of this construction can jump at least three times as high as the stroke length of its actuators, recording a maximum jump height of 48 mm using a stroke of 15 mm. This finding supports the feasibility of a larger robot based on this design.by Robert A. Hummel.S.B

MULTI-PLAYER BELIEF CALCULI: MODELS AND APPLICATIONS

In developing methods for dealing with uncertainty in reasoning systems, it is important to consider the needs of the target applications. In particular, when the source of inferential uncertainty can be tracked to distributions of expert opinions, there might be different ways to model the representation and combination of these opinions. In this paper we present the notion of multiplayer belief calculi - a framework that takes into consideration not only the 'regular' type of evidential uncertainty, but also the diversity of expert opinions when the evidence is held fixed. Using several applied examples, we show how the basic framework can be naturally extended to support different application needs and different sets of assumptions about the nature of the inference process.Information Systems Working Papers Serie

ON THE USE OF THE DEMPSTER SHAFER MODEL IN INFORMATION INDEXING AND RETRIEVAL APPLICATIONS

The Dempster Shafer theory of evidence concerns the elicitation and manipulation of degrees of belief rendered by multiple sources of evidence to a common set of propositions. Information indexing and retrieval applications use a variety of quantitative means - both probabilistic and quasi-probabilistic - to represent and manipulate relevance numbers and index vectors. Recently, several proposals were made to use the Dempster Shafes model as a relevance calculus in such applications. The paper provides a critical review of these proposals, pointing at several theoretical caveats and suggesting ways to resolve them. The methodology is based on expounding a canonical indexing model whose relevance measures and combination mechanisms are shown to be isomorphic to Shafer's belief functions and to Dempster's rule, respectively. Hence, the paper has two objectives: (i) to describe and resolve some caveats in the way the Dempster Shafer theory is applied to information indexing and retrieval, and (ii) to provide an intuitive interpretation of the Dempster Shafer theory, as it unfolds in the simple context of a canonical indexing model.Information Systems Working Papers Serie

COMPROMISE REACHING MECHANISMS IN MULTI-GROUP/MULTI-PLAYER NEGOTIATION PROCESSES

We consider a situation in which multiple decision-makers who are partitioned into two or more distinct groups are asked to recommend a uniform course of action which is drawn from a finite and explicit set of potential alternatives. We present group-level and player-level mechanisms to reach a compromise decision under such circumstances. The group-level mechanism is based on the Dempster-Shafer theory of evidence; The player-level mechanism employs a set-product operation that aggregates the individual decisions over a certain space of committees. Previous research established that the two mechanisms are isomorphic, which, in the contest of the present paper, implies that they yield the same compromise decision. However, unlike the Dempster-Shafer theory, which was criticized for lack of external validity, the set-product mechanism has plausible properties in the contest of group decision making. With that in mind, the paper seeks to (i) report about an interesting relationship between group decision research and AI methods to manage uncertainty, and (ii) build a foundation for an inter-disciplinary research that exploits this linkage.Information Systems Working Papers Serie

Infrastructure for large-scale tests in marine autonomy

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 141-147).This thesis focuses on the development of infrastructure for research with large-scale autonomous marine vehicle fleets and the design of sampling trajectories for compressive sensing (CS). The newly developed infrastructure includes a bare-bones acoustic modem and two types of low-cost and scalable vehicles. One vehicle is a holonomic raft designed for station-keeping and precise maneuvering, and the other is a streamlined kayak for traveling longer distances. The acoustic modem, like the vehicles, is inexpensive and scalable, providing the capability of a large-scale, low-cost underwater acoustic network. With these vehicles and modems we utilize compressive sensing, a recently developed framework for sampling sparse signals that offers dramatic reductions in the number of samples required for high fidelity reconstruction of a field. Our novel CS sampling techniques introduce engineering constraints including movement and measurement costs to better apply CS to sampling with mobile agents. The vehicles and modems, along with compressive sensing, strengthen the movement towards large scale autonomy in the ocean environment.by Robert Andrew Hummel.S.M

COMPROMISE REACHING MECHANISMS IN MULTI-GROUP/MULTI-PLAYER NEGOTIATION PROCESSES

We consider a situation in which multiple decision-makers who are partitioned into two or more distinct groups are asked to recommend a uniform course of action which is drawn from a finite and explicit set of potential alternatives. We present group-level and player-level mechanisms to reach a compromise decision under such circumstances. The group-level mechanism is based on the Dempster-Shafer theory of evidence; The player-level mechanism employs a set-product operation that aggregates the individual decisions over a certain space of committees. Previous research established that the two mechanisms are isomorphic, which, in the contest of the present paper, implies that they yield the same compromise decision. However, unlike the Dempster-Shafer theory, which was criticized for lack of external validity, the set-product mechanism has plausible properties in the contest of group decision making. With that in mind, the paper seeks to (i) report about an interesting relationship between group decision research and AI methods to manage uncertainty, and (ii) build a foundation for an inter-disciplinary research that exploits this linkage.Information Systems Working Papers Serie

Distribution of Faraday Rotation Measure in Jets from Active Galactic Nuclei II. Prediction from our Sweeping Magnetic Twist Model for the Wiggled Parts of AGN Jets and Tails

Distributions of Faraday rotation measure (FRM) and the projected magnetic field derived by a 3-dimensional simulation of MHD jets are investigated based on our "sweeping magnetic twist model". FRM and Stokes parameters were calculated to be compared with radio observations of large scale wiggled AGN jets on kpc scales. We propose that the FRM distribution can be used to discuss the 3-dimensional structure of magnetic field around jets and the validity of existing theoretical models, together with the projected magnetic field derived from Stokes parameters. In the previous paper, we investigated the basic straight part of AGN jets by using the result of a 2-dimensional axisymmetric simulation. The derived FRM distribution has a general tendency to have a gradient across the jet axis, which is due to the toroidal component of the magnetic field generated by the rotation of the accretion disk. In this paper, we consider the wiggled structure of the AGN jets by using the result of a 3-dimensional simulation. Our numerical results show that the distributions of FRM and the projected magnetic field have a clear correlation with the large scale structure of the jet itself, namely, 3-dimensional helix. Distributions, seeing the jet from a certain direction, show a good matching with those in a part of 3C449 jet. This suggests that the jet has a helical structure and that the magnetic field (especially the toroidal component) plays an important role in the dynamics of the wiggle formation because it is due to a current-driven helical kink instability in our model.Comment: Accepted for publication in Ap

Short-term effects of video gaming on brain response during working memory performance

Breaks filled with different break activities often interrupt cognitive performance in everyday life. Previous studies have reported that both enhancing and deteriorating effects on challenging ongoing tasks such as working memory updating, depend on the type of break activity. However, neural mechanisms of these break-related alterations in working memory performance have not been studied, to date. Therefore, we conducted a brain imaging study to identify the neurobiological correlates of effects on the n-back working memory task related to different break activities. Before performing the n-back task in the magnetic resonance imaging (MRI) scanner, young adults were exposed to break activities in the MRI scanner involving (i) eyes-open resting, (ii) listening to music, and (iii) playing the video game “Angry Birds”. Heart rate was measured by a pulse oximeter during the experiment. We found that increased heart rate during gaming as well as decreased relaxation levels after a video gaming break was related to poorer n-back task performance, as compared to listening to music. On the neural level, video gaming reduced supplementary motor area activation during working memory performance. These results may indicate that video gaming during a break may affect working memory performance by interfering with arousal state and frontal cognitive control functions

Minimally Invasive Mitral Valve Surgery I: Patient Selection, Evaluation, and Planning.

Widespread adoption of minimally invasive mitral valve repair and replacement may be fostered by practice consensus and standardization. This expert opinion, first of a 3-part series, outlines current best practices in patient evaluation and selection for minimally invasive mitral valve procedures, and discusses preoperative planning for cannulation and myocardial protection