Improved Practical Matrix Sketching with Guarantees

Matrices have become essential data representations for many large-scale problems in data analytics, and hence matrix sketching is a critical task. Although much research has focused on improving the error/size tradeoff under various sketching paradigms, the many forms of error bounds make these approaches hard to compare in theory and in practice. This paper attempts to categorize and compare most known methods under row-wise streaming updates with provable guarantees, and then to tweak some of these methods to gain practical improvements while retaining guarantees. For instance, we observe that a simple heuristic iSVD, with no guarantees, tends to outperform all known approaches in terms of size/error trade-off. We modify the best performing method with guarantees FrequentDirections under the size/error trade-off to match the performance of iSVD and retain its guarantees. We also demonstrate some adversarial datasets where iSVD performs quite poorly. In comparing techniques in the time/error trade-off, techniques based on hashing or sampling tend to perform better. In this setting we modify the most studied sampling regime to retain error guarantee but obtain dramatic improvements in the time/error trade-off. Finally, we provide easy replication of our studies on APT, a new testbed which makes available not only code and datasets, but also a computing platform with fixed environmental settings.Comment: 27 page

Central Tottori Earthquake geodetic slip inversion tools and data

This dataset contains all the data required to run perform a geodetic slip inversion using the software slipBERI (https://doi.org/10.5518/444) for the 2016, Mw 6.2 Central Tottori, Japan earthquake. Additionally this dataset contains the models runs of the solutions found in the associated thesis and paper

Fault roughness of the Campo Felice fault – data and scripts

This dataset contains fault surface scans of the Campo Felice fault in the Italian Apennines, and scripts required to process these scans in order to investigate the fractal properties of fault roughness

Napa Valley Earthquake geodetic slip inversion tools and data

This dataset contains all the data required to run perform a geodetic slip inversion using the software slipBERI (https://doi.org/10.5518/444) for the 2014 Mw 6.0 Napa Valley, California, earthquake. Additionally this dataset contains the models runs of the solutions found in the associated thesis and paper

Teacher Beliefs and Subject Matter Boundaries: The Struggle for Curricular Transformation Among Teachers of Adults

Teachers of adult learners in formal settings are increasingly exploring more integrated approaches to curriculum and teaching. One location for such work is the community college. Among these teachers, however, who are traditionally content experts, an integrated approach often represents a paradigmatic shift in their understanding of what is most worth knowing. Little is known about how these teachers\u27 beliefs influence, change, and are changed by participation in such curriculum efforts. This study reports on the beliefs and meaning and perspectives of one group of teachers attempting to bring about more curricular coherence and integration within four different disciplines of developmental education

Seeking Academic Redemption: The Reconstruction of Learner Identity Among “Underprepared” Adults

A desire to promote learning for personal development and change dominates much of research and practice in adult and higher education. Few studies, however, have attempted to describe how participating learners experience developmental programs, or how they make sense of these programs in the their particular life contexts. In this study, we describe the re-making of a “learner” identity, as narrated by underprepared adults enrolled in a developmentally-oriented community college program

Building information modelling, a tool for green built environment

To create any green built environment, it is of primary importance that project stakeholders including designer, energy modeller, estimator, climatologist, environmentalist, etc. contribute and become accountable towards the same. Building information modelling (BIM) is one such tool which not only stands as a 3D geometric modelling tool, but also supplies useful information, data about several aspects throughout the life-cycle of a project such as construction process, design and development of a facility, quantities and scheduling, fabrication process, and provides information required for facilities managers, stakeholders. Hence BIM based approach could also be extended for designing and developing green built environment. This piece of research explores role of building information modelling methodology in the development of green built environment. A BIM based approach assists professionals during the conception of green built environment in predicting the outcome(s) of its construction to minimise its impact on the environment throughout its life-cycle. A building model developed on the principles of BIM virtual representation of building can be presented to person/expert from non-construction/architectural background. It can provide appropriate data on demand to perform energy analysis and hence facilitates very complex and so call tedious process of sustainable design, such as day-lighting, morphological analysis, computational fluidic dynamics (CFD), material takeoff, estimation, scheduling, energy modelling, resource planning, and so on

Real-time ridesharing : exploring the opportunities and challenges of designing a technology-based rideshare trial for the MIT community

Thesis (S.M. in Transportation)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering; and, (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 181-188).The potential benefits from increased ridesharing are substantial, and impact a wide range of stakeholders. In a properly applied rideshare scheme, drivers and passengers achieve cost savings, they potentially achieve travel time savings, and they benefit from increased travel options. Employers can reduce expensive parking construction or leasing, and benefit from higher worker productivity. Society benefits from congestion reduction, energy security improvements, greenhouse gas (GHG) emission reductions and increased social equity. Unfortunately, ridesharing's historical success has been rather modest, with a substantial decrease in popularity since the 1970's and participation that remains near an all-time low. Clearly there is a disconnect between the purported benefits and the real or perceived challenges associated with sharing rides. This thesis asks why ridesharing is not more popular than current participation suggests, and what can be done to encourage greater participation going forward? After a review of past and present rideshare initiatives, it becomes clear that there is no single challenge to be overcome that will increase interest and participation in ridesharing. Rather, the 'rideshare challenge' is a series of economic, behavioral, institutional and technological obstacles to be addressed. Yet, two opportunities show particular promise at helping overcome these challenges - a focus on large employers, and a technology-based service innovation known as "real-time" ridesharing. Large employers are a unique type of institution that can successfully influence private household travel decisions while simultaneously advancing employer-specific goals and various societal goals. "Real-time" ridesharing extends the range of existing rideshare options available to travelers and it begins to address a number of challenges associated with ridesharing. To increase rideshare participation going forward, this thesis proposes a detailed design for an employer based, technology-focused rideshare trial for the Massachusetts Institute of Technology (MIT), supported by a rigorous, Institute-specific analysis of rideshare viability. The trial is designed to be expanded to other institutions in the MIT/Kendall Square area of Cambridge, MA in the future. The analysis suggests that on an ideal day, approximately 65% of consistent, single occupant commuters could share rides, leading to a 19% reduction in Institute-wide, commuting trip VMT. The trial design focuses on the use of technology, incentives and personalized marketing to overcome the 'rideshare challenge' and realize a significant portion of this best case VMT reduction.by Andrew M. Amey.M.C.P.S.M.in Transportatio

Simultaneous Determination of Human Plasma Levels of Citalopram, Paroxetine, Sertraline, and Their Metabolites by Gas Chromatography—Mass Spectrometry

A gas chromatography—mass spectrometry method is presented which allows the simultaneous determination of the plasma concentrations of the selective serotonin reuptake inhibitors citalopram, paroxetine, sertraline, and their pharmacologically active N-demethylated metabolites (desmethylcitalopram, didesmethylcitalopram, and desmethylsertraline) after derivatization with the reagent N-methyl-bis(trifluoroacetamide). No interferences from endogenous compounds are observed following the extraction of plasma samples from six different human subjects. The standard curves are linear over a working range of 10-500 ng/mL for citalopram, 10-300 ng/mL for desmethylcitalopram, 5-60 ng/mL for didesmethylcitalopram, 20-400 ng/mL for sertraline and desmethylsertraline, and 10-200 ng/mL for paroxetine. Recoveries measured at three concentrations range from 81 to 118% for the tertiary amines (citalopram and the internal standard methylmaprotiline), 73 to 95% for the secondary amines (desmethylcitalopram, paroxetine and sertraline), and 39 to 66% for the primary amines (didesmethylcitalopram and desmethylsertraline). Intra- and interday coefficients of variation determined at three concentrations range from 3 to 11 % for citalopram and its metabolites, 4 to 15% for paroxetine, and 5 to 13% for sertraline and desmethylsertraline. The limits of quantitation of the method are 2 ng/mL for citalopram and paroxetine, 1 ng/mL for sertraline, and 0.5 ng/mL for desmethylcitalopram, didesmethylcitalopram, and desmethylsertraline. No interferences are noted from 20 other psychotropic drugs. This sensitive and specific method can be used for single-dose pharmacokinetics. It is also useful for therapeutic drug monitoring of these three drugs and could possibly be adapted for the quantitation of the two other selective serotonin reuptake inhibitors on the market, namely fluoxetine and fluvoxamin