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Last Build Date: Fri, 24 Feb 2017 01:35:19 PST

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Relaxed decidability and the robust semantics of Metric Temporal Logic

Thu, 23 Feb 2017 08:46:32 PST

Relaxed notions of decidability widen the scope of automatic verification of hybrid systems. In quasi-decidability and $\delta$-decidability, the fundamental compromise is that if we are willing to accept a slight error in the algorithm's answer, or a slight restriction on the class of problems we verify, then it is possible to obtain practically useful answers. This paper explores the connections between relaxed decidability and the robust semantics of Metric Temporal Logic formulas. It establishes a formal equivalence between the robustness degree of MTL specifications, and the imprecision parameter $\delta$ used in $\delta$-decidability when it is used to verify MTL properties. We present an application of this result in the form of an algorithm that generates new constraints to the $\delta$-decision procedure from falsification runs, which speeds up the verification run. We then establish new conditions under which robust testing, based on the robust semantics of MTL, is in fact a quasi-semidecision procedure. These results allow us to delimit what is possible with fast, robustness-based methods, accelerate (near-)exhaustive verification, and further bridge the gap between verification and simulation.







Why Are There Descriptive Norms? Because We Looked for Them

Wed, 22 Feb 2017 13:20:37 PST

In this work, we present a mathematical model for the emergence of descriptive norms, where the individual decision problem is formalized with the standard Bayesian belief revision machinery. Previous work on the emergence of descriptive norms has relied on heuristic modeling. In this paper we show that with a Bayesian model we can provide a more general picture of the emergence of norms, which helps to motivate the assumptions made in heuristic models. In our model, the priors formalize the belief that a certain behavior is a regularity. The evidence is provided by other group members’ behavior and the likelihood by their reliability. We implement the model in a series of computer simulations and examine the group-level outcomes. We claim that domain-general belief revision helps explain why we look for regularities in social life in the first place. We argue that it is the disposition to look for regularities and react to them that generates descriptive norms. In our search for rules, we create them.




A Structured Approach to a Diagnostic of Collective Practices

Wed, 22 Feb 2017 13:20:33 PST

“How social norms change” is not only a theoretical question but also an empirical one. Many organizations have implemented programs to abandon harmful social norms. These programs are standardly monitored and evaluated with a set of empirical tools. While monitoring and evaluation (M&E) of changes in objective outcomes and behaviors is well developed, we will argue that M&E of changes in the wide range of beliefs and preferences important to social norms is still problematic. In this paper, we first present a theoretical framework and then show how it should guide social norms measurement. As a case study, we focus on the harmful practice of child marriage. We show how an operational theory of social norms can guide the design of surveys, experiments, and vignettes. We use examples from existing research to illustrate how to study social norms change.




Is Participation Contagious? Evidence From a Household Vector Control Campaign in Urban Peru

Wed, 22 Feb 2017 13:20:29 PST

Objective: High rates of household participation are critical to the success of door-to-door vector control campaigns. We used the Health Belief Model to assess determinants of participation, including neighbour participation as a cue to action, in a Chagas disease vector control campaign in Peru.

Methods: We evaluated clustering of participation among neighbours; estimated participation as a function of household infestation status, neighbourhood type and number of participating neighbours; and described the reported reasons for refusal to participate in a district of 2911 households.

Results: We observed significant clustering of participation along city blocks (p<0.0001). Participation was significantly higher for households in new versus established neighbourhoods, for infested households, and for households with more participating neighbours. The effect of neighbour participation was greater in new neighbourhoods.

Conclusions: Results support a ‘contagion’ model of participation, highlighting the possibility that one or two participating households can tip a block towards full participation. Future campaigns can leverage these findings by making participation more visible, by addressing stigma associated with spraying, and by employing group incentives to spray.




Do the Right Thing: But Only if Others do so

Wed, 22 Feb 2017 13:20:25 PST

Social norms play an important role in individual decision making. Bicchieri (2006) argues that two different expectations influence our choice to obey a norm: what we expect others to do (empirical expectations) and what we believe others think we ought to do (normative expectations). Little is known about the relative importance of these two types of expectation in individuals’ decisions, an issue that is particularly important when normative and empirical expectations are in conflict (e.g., systemic corruption, high crime cities). In this paper, we report data from Dictator game experiments where we exogenously manipulate dictators’ expectations in the direction of either selfishness or fairness. When normative and empirical expectations are in conflict, we find that empirical expectations about other dictators’ choices significantly predict a dictator’s own choice. However, dictators’ expectations regarding what other dictators think ought to be done do not have a significant impact on their decisions after controlling for empirical expectations. Our findings about the crucial influence of empirical expectations are important for designing institutions or policies aimed at discouraging undesirable behavior.




2.3.1 - Differentials

Wed, 22 Feb 2017 09:00:55 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




2.2.2.2 - Bonus

Wed, 22 Feb 2017 08:55:19 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




2.2.2.1 - Higher Derivatives

Wed, 22 Feb 2017 08:50:21 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




2.2.1 - Linearization

Wed, 22 Feb 2017 08:40:21 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




2.1.2.2 - Bonus

Wed, 22 Feb 2017 08:40:17 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




2.1.2.1 - Differentiation Rules

Wed, 22 Feb 2017 08:31:55 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




2.1.1 - Derivatives

Wed, 22 Feb 2017 08:31:52 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.4.3.2 - Bonus

Wed, 22 Feb 2017 08:10:19 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.4.3.1 - Orders of Growth

Wed, 22 Feb 2017 08:05:51 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.4.2 - L'Hopitals Rule

Wed, 22 Feb 2017 07:45:26 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.4.1 - Limits

Wed, 22 Feb 2017 07:35:54 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.3.4 - Expansion Points

Wed, 22 Feb 2017 07:30:17 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.3.3.2 - Bonus

Wed, 22 Feb 2017 07:25:25 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.3.3.1 - Convergence

Wed, 22 Feb 2017 07:25:22 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.3.2 - Computing Taylor Series

Wed, 22 Feb 2017 07:25:18 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.3.1 - Taylor Series

Wed, 22 Feb 2017 07:25:15 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.2.2.2 - Bonus

Wed, 22 Feb 2017 07:25:11 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.










Does Transcranial Direct Current Stimulation Improve Healthy Working Memory?: A Meta-Analytic Review

Wed, 22 Feb 2017 07:17:52 PST

Transcranial direct current stimulation (tDCS) has been reported to improve working memory (WM) performance in healthy individuals, suggesting its value as a means of cognitive enhancement. However, recent meta-analyses concluded that tDCS has little or no effect on WM in healthy participants. In this article, we review reasons why these meta-analyses may have underestimated the effect of tDCS on WM and report a more comprehensive and arguably more sensitive meta-analysis. Consistent with our interest in enhancement, we focused on anodal stimulation. Thirty-one articles matched inclusion criteria and were included in four primary meta-analyses assessing the WM effects of anodal stimulation over the left and right dorsolateral pFC (DLPFC) and right parietal lobe as well as left DLPFC stimulation coupled with WM training. These analyses revealed a small but significant effect of left DLPFC stimulation coupled with WM training. Left DLPFC stimulation alone also enhanced WM performance, but the effect was reduced to nonsignificance after correction for publication bias. No other effects were significant, including a variety of tested moderators. Additional meta-analyses were undertaken with study selection criteria based on previous meta-analyses, to reassess the findings from these studies using the analytic methods of this study. These analyses revealed a mix of significant and nonsignificant small effects. We conclude that the primary WM enhancement potential of tDCS probably lies in its use during training.




Do Political and Economic Choices Rely on Common Neural Substrates? A Systematic Review of the Emerging Neuropolitics Literature

Wed, 22 Feb 2017 07:17:42 PST

The methods of cognitive neuroscience are beginning to be applied to the study of political behavior. The neural substrates of value-based decision-making have been extensively examined in economic contexts; this might provide a powerful starting point for understanding political decision-making. Here, we asked to what extent the neuropolitics literature to date has used conceptual frameworks and experimental designs that make contact with the reward-related approaches that have dominated decision neuroscience. We then asked whether the studies of political behavior that can be considered in this light implicate the brain regions that have been associated with subjective value related to “economic” reward. We performed a systematic literature review to identify papers addressing the neural substrates of political behavior and extracted the fMRI studies reporting behavioral measures of subjective value as defined in decision neuroscience studies of reward. A minority of neuropolitics studies met these criteria and relatively few brain activation foci from these studies overlapped with regions where activity has been related to subjective value. These findings show modest influence of reward-focused decision neuroscience on neuropolitics research to date. Whether the neural substrates of subjective value identified in economic choice paradigms generalize to political choice thus remains an open question. We argue that systematically addressing the commonalities and differences in these two classes of value-based choice will be important in developing a more comprehensive model of the brain basis of human decision-making.




Ethical Challenges in Preclinical Alzheimer's Disease Observational Studies and Trials: Results of the Barcelona Summit

Wed, 22 Feb 2017 07:17:34 PST

Alzheimer's disease (AD) is among the most significant health care burdens. Disappointing results from clinical trials in late-stage AD persons combined with hopeful results from trials in persons with early-stage suggest that research in the preclinical stage of AD is necessary to define an optimal therapeutic success window. We review the justification for conducting trials in the preclinical stage and highlight novel ethical challenges that arise and are related to determining appropriate risk-benefit ratios and disclosing individuals' biomarker status. We propose that to conduct clinical trials with these participants, we need to improve public understanding of AD using unified vocabulary, resolve the acceptable risk-benefit ratio in asymptomatic participants, and disclose or not biomarker status with attention to study type (observational studies vs clinical trials). Overcoming these challenges will justify clinical trials in preclinical AD at the societal level and aid to the development of societal and legal support for trial participants.




A Pragmatic Analysis of the Regulation of Consumer Transcranial Direct Current Stimulation (TDCS) Devices in the United States

Wed, 22 Feb 2017 07:17:27 PST

Several recent articles have called for the regulation of consumer transcranial direct current stimulation (tDCS) devices, which provide low levels of electrical current to the brain. However, most of the discussion to-date has focused on ethical or normative considerations; there has been a notable absence of scholarship regarding the actual legal framework in the United States. This article aims to fill that gap by providing a pragmatic analysis of the consumer tDCS market and relevant laws and regulations. In the five main sections of this manuscript, I take into account (a) the history of the do-it-yourself tDCS movement and the subsequent emergence of direct-to-consumer devices; (b) the statutory language of the Federal Food, Drug and Cosmetic Act and how the definition of a medical device—which focuses on the intended use of the device rather than its mechanism of action—is of paramount importance for discussions of consumer tDCS device regulation; (c) how both the Food and Drug Administration (FDA) and courts have understood the FDA's jurisdiction over medical devices in cases where the meaning of ‘intended use’ has been challenged; (d) an analysis of consumer tDCS regulatory enforcement action to-date; and (e) the multiple US authorities, other than the FDA, that can regulate consumer brain stimulation devices. Taken together, this paper demonstrates that rather than a ‘regulatory gap,’ there are multiple, distinct pathways by which consumer tDCS can be regulated in the United States.
















Letter from the Editor

Tue, 21 Feb 2017 14:42:13 PST




Volume 23, Issue 2 Fall 2016

Tue, 21 Feb 2017 14:42:09 PST




Bitstreams: The Future of Digital Literary Heritage

Tue, 21 Feb 2017 12:12:18 PST

Matthew Kirschenbaum, Associate Professor of English and Associate Director of the Maryland Institute for Technology in the Humanities, describes the lectures as an assessment of the future of literary heritage—archives, public memory, and scholarship in the face of the ubiquity of computers as instruments of composition, editing, and book design; the distribution of books through multiple media formats and platforms; the profusion of the literary conversation online; and the hybridity of the contemporary media archive.

Matthew Kirschenbaum has written and collaborated in the publishing of four books and often speaks and writes on the topics of Digital Humanities and New Media. His work has received coverage in The Atlantic, Slate, The New York Times, The Guardian, NPR, Wired, Boing Boing, Slashdot, and The Chronicle of Higher Education.



















1.2.2.1 - Exponentials

Mon, 20 Feb 2017 13:45:13 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.2.1 - Functions

Mon, 20 Feb 2017 13:30:17 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




1.1 - Introduction

Mon, 20 Feb 2017 13:10:07 PST

In this series, you will find video assets for all video assets from the massive, open, online course, Calculus: Single Variable. The course is taught by Robert Ghrist of the University of Pennsylvania.




Senior Honors Thesis Abstracts

Mon, 20 Feb 2017 11:27:25 PST










The War That Congress Waged

Mon, 20 Feb 2017 11:27:13 PST







Letter from the Editor

Mon, 20 Feb 2017 11:27:06 PST




Volume 23, Issue 1 Spring 2016

Mon, 20 Feb 2017 11:27:02 PST