642 research outputs found

    The historical performance of equity REITs : a seasonsed index approach

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    Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1994.Includes bibliographical references (leaves 65-66).by Jeffrey M. Johnston.M.S

    Urban Hospitals: Their Plight and Mission

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    Sensor-rich real-time adaptive gesture and affordance learning platform for electronic music control

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    Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2004.Includes bibliographical references (p. [151]-156).Acoustic musical instruments have traditionally featured static mappings from input gesture to output sound, their input affordances being tied to the physics of their sound-production mechanism. More recently, the advent of digital sound synthesizers and electronic music controllers has abolished the tight coupling between input gesture and resultant sound, making an exponentially large range of input-to-output mappings possible, as well as an infinite set of possible timbres. This revolutionary change in the way sound can be produced and controlled brings with it the burden of design: Compelling and natural mappings from gesture to sound now must be created in order to create a playable electronic music instrument. The goal of this thesis is to present a device that allows flexible assignment of input gesture to output sound, so acting as a laboratory to help further understanding about the connection from gesture to sound. An embodied multi-degree-of-freedom gestural input device was constructed. The device was built to support six-degree-of-freedom inertial sensing, five isometric buttons, two digital buttons, two-axis bend sensing, isometric rotation sensing, and isotonic electric field sensing of position. Software was written to handle the incoming serial data, and to implement a trainable interface by which a user can explore the sounds possible with the device, associate a custom inertial gesture with a sound for later playback, make custom input degree-of-freedom (DOF) to effect modulation mappings, and play with the resulting configuration. A user study with 25 subjects was run to evaluate the system in terms of its engaging-ness, enjoyability, ability to inspire interest in future play and performance,(cont.) ease of gesturing and novelty. In addition to these subjective measures, implicit data was collected about the types of gesture-to-sound and input-DOF-to-effect mappings that the subjects created. Favorable and interesting results were found in the data from the study, indicating that a flexible trainable musical instrument is not only a compelling performance tool, but is a useful laboratory for understanding the connection between human gesture and sound.by Jeffrey Merrill.S.M

    Interaction with embodied media

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2009.Includes bibliographical references (p. 213-222).The graphical user interface has become the de facto metaphor for the majority of our diverse activities using computers, yet the desktop environment provides a one size fits all user interface. This dissertation argues that for the computer to fully realize its potential to significantly extend our intellectual abilities, new interaction techniques must call upon our bodily abilities to manipulate objects, enable collaborative work, and be usable in our everyday physical environment. In this dissertation I introduce a new human-computer interaction concept, embodied media. An embodied media system physically represents digital content such as files, variables, or other program constructs with a collection of self-contained, interactive electronic tokens that can display visual feedback and can be manipulated gesturally by users as a single, coordinated interface. Such a system relies minimally on external sensing infrastructure compared to tabletop or augmented reality systems, and is a more general-purpose platform than most tangible user interfaces. I hypothesized that embodied media interfaces provide advantages for activities that require the user to efficiently arrange and adjust multiple digital content items. Siftables is the first instantiation of an embodied media interface. I built 180 Siftable devices in three design iterations, and developed a programming interface and various applications to explore the possibilities of embodied media.(cont.) In a survey, outside developers reported that Siftables created new user interface possibilities, and that working with Siftables increased their interest in human-computer interaction and expanded their ideas about the field. I evaluated a content organization application with users, finding that Siftables offered an advantage over the mouse+graphical user interface (GUI) for task completion time that was amplified when participants worked in pairs, and a digital image manipulation application in which participants preferred Siftables to the GUI in terms of enjoyability, expressivity, domain learning, and for exploratory/quick arrangement of items.by David Jeffrey Merrill.Ph.D

    Substance abuse prevention infrastructure: a survey-based study of the organizational structure and function of the D.A.R.E. program

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    BACKGROUND: The only national drug abuse prevention delivery system that supports the rapid diffusion of new prevention strategies and includes uniform training and credentialing of instructors who are monitored for quality implementation of prevention programming is the Drug Abuse Resistance Education network (D.A.R.E.) linking community law enforcement to schools. Analysis of the organizational structure and function of D.A.R.E. provides an understanding of the essential parameters of this successful delivery system that can be used in the development of other types of national infrastructures for community-based prevention services. Information regarding organizational structure and function around funding issues, training, quality control and community relationships was gathered through telephone surveys with 50 state D.A.R.E. coordinators (including two major cities), focus groups with local D.A.R.E. officers and mentors, and interviews with national D.A.R.E. office staff. RESULTS: The surveys helped identify several strengths inherent in the D.A.R.E. program necessary for building a prevention infrastructure, including a well-defined organizational focus (D.A.R.E. America), uniform training and means for rapid dissemination (through its organized training structure), continuing education mechanisms (through the state and national conference and website), mechanisms for program monitoring and fidelity of implementation (formal and informal), branding and, for several states, predictable and consistent financing. Weaknesses of the program as currently structured include unstable funding and the failure to incorporate components for the continual upgrading of curricula reflecting research evidence and "principles of prevention". CONCLUSION: The D.A.R.E. organization and service delivery network provides a framework for the rapid dissemination of evidence-based prevention strategies. The major strength of D.A.R.E. is its natural affiliation to local law enforcement agencies through state coordinators. Through these affiliations, it has been possible for D.A.R.E. to become established nationally within a few years and internationally within a decade. Understanding how this structure developed and currently functions provides insights into how other such delivery systems could be developed

    Acute Beetroot Juice Ingestion Increases Nitric Oxide Bioavailability Without Changing Oral Microbial Composition in Healthy Young Women

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    Dietary nitrate supplementation can elicit beneficial health and exercise performance effects. Oral microbiota are critical for the metabolism of exogenously consumed nitrate; however, limited data are available on the influence of dietary nitrate ingestion on bacterial taxa and in women. PURPOSE: To investigate if acute dietary nitrate ingestion alters the oral microbiota in young healthy women compared to a nitrate-depleted placebo. METHODS: In a randomized double-blinded crossover design, fifteen recreationally active women (mean ± SD: age 20 ± 1 years; body mass 63 ± 10 kg; height 1.68 ± 0.1 m) participated in two conditions to ingest nitrate-rich beetroot juice (BR; 12 mmol of nitrate) and nitrate-depleted beetroot juice (PL, negligible nitrate), 2.5 hours prior to a resting blood draw and buccal swab sample. Plasma [nitrate] and [nitrite] were analyzed using gas phase chemiluminescence. Buccal swab samples were used for DNA extraction and isolation. DNA was amplified using polymerase chain reaction targeting the V3 - V4 region of the 16S rRNA gene. Following index PCR, amplicons were pooled and sequenced using the iSeq Illumina NGS sequencer. Reads were clustered into amplicon sequence variants and analyzed for alpha and beta diversity and relative abundance. RESULTS: BR increased plasma [nitrate] (PL: 52 ± 14 µM vs. BR: 629 ± 132 µM, P \u3c 0.001) and plasma [nitrite] (PL: 276 ± 286 nM vs. BR: 703 ± 391 nM, P \u3c 0.001). One sample had insufficient DNA and thus, a subset of samples was analyzed for oral microbial composition (n = 14). Alpha (i.e., species richness or evenness) and beta diversity was not different between PL and BR (P \u3e 0.05). The relative abundance of the phylum and genus were not influenced by BR (P \u3e 0.05). CONCLUSION: Acute nitrate ingestion did not improve or worsen the composition of global or lower taxonomic levels of bacteria in young recreationally active women. These data indicate that acute nitrate ingestion is an intervention to rapidly increase nitric oxide bioavailability in young recreationally active women, which is an effect that did not require changes to the oral microbial community. Further research is required to understand the impact of dosing regimen and population on oral bacterial taxa and the efficacy of nitrate on nitrate-induced effects

    Application of a single-objective, hybrid genetic algorithm approach to pharmacokinetic model building.

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    A limitation in traditional stepwise population pharmacokinetic model building is the difficulty in handling interactions between model components. To address this issue, a method was previously introduced which couples NONMEM parameter estimation and model fitness evaluation to a single-objective, hybrid genetic algorithm for global optimization of the model structure. In this study, the generalizability of this approach for pharmacokinetic model building is evaluated by comparing (1) correct and spurious covariate relationships in a simulated dataset resulting from automated stepwise covariate modeling, Lasso methods, and single-objective hybrid genetic algorithm approaches to covariate identification and (2) information criteria values, model structures, convergence, and model parameter values resulting from manual stepwise versus single-objective, hybrid genetic algorithm approaches to model building for seven compounds. Both manual stepwise and single-objective, hybrid genetic algorithm approaches to model building were applied, blinded to the results of the other approach, for selection of the compartment structure as well as inclusion and model form of inter-individual and inter-occasion variability, residual error, and covariates from a common set of model options. For the simulated dataset, stepwise covariate modeling identified three of four true covariates and two spurious covariates; Lasso identified two of four true and 0 spurious covariates; and the single-objective, hybrid genetic algorithm identified three of four true covariates and one spurious covariate. For the clinical datasets, the Akaike information criterion was a median of 22.3 points lower (range of 470.5 point decrease to 0.1 point decrease) for the best single-objective hybrid genetic-algorithm candidate model versus the final manual stepwise model: the Akaike information criterion was lower by greater than 10 points for four compounds and differed by less than 10 points for three compounds. The root mean squared error and absolute mean prediction error of the best single-objective hybrid genetic algorithm candidates were a median of 0.2 points higher (range of 38.9 point decrease to 27.3 point increase) and 0.02 points lower (range of 0.98 point decrease to 0.74 point increase), respectively, than that of the final stepwise models. In addition, the best single-objective, hybrid genetic algorithm candidate models had successful convergence and covariance steps for each compound, used the same compartment structure as the manual stepwise approach for 6 of 7 (86 %) compounds, and identified 54 % (7 of 13) of covariates included by the manual stepwise approach and 16 covariate relationships not included by manual stepwise models. The model parameter values between the final manual stepwise and best single-objective, hybrid genetic algorithm models differed by a median of 26.7 % (q₁ = 4.9 % and q₃ = 57.1 %). Finally, the single-objective, hybrid genetic algorithm approach was able to identify models capable of estimating absorption rate parameters for four compounds that the manual stepwise approach did not identify. The single-objective, hybrid genetic algorithm represents a general pharmacokinetic model building methodology whose ability to rapidly search the feasible solution space leads to nearly equivalent or superior model fits to pharmacokinetic data
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