Approximation Algorithms for Route Planning with Nonlinear Objectives

We consider optimal route planning when the objective function is a general nonlinear and non-monotonic function. Such an objective models user behavior more accurately, for example, when a user is risk-averse, or the utility function needs to capture a penalty for early arrival. It is known that as nonlinearity arises, the problem becomes NP-hard and little is known about computing optimal solutions when in addition there is no monotonicity guarantee. We show that an approximately optimal non-simple path can be efficiently computed under some natural constraints. In particular, we provide a fully polynomial approximation scheme under hop constraints. Our approximation algorithm can extend to run in pseudo-polynomial time under a more general linear constraint that sometimes is useful. As a by-product, we show that our algorithm can be applied to the problem of finding a path that is most likely to be on time for a given deadline.Comment: 9 pages, 2 figures, main part of this paper is to be appear in AAAI'1

Autoencoders and Generative Adversarial Networks for Imbalanced Sequence Classification

Generative Adversarial Networks (GANs) have been used in many different applications to generate realistic synthetic data. We introduce a novel GAN with Autoencoder (GAN-AE) architecture to generate synthetic samples for variable length, multi-feature sequence datasets. In this model, we develop a GAN architecture with an additional autoencoder component, where recurrent neural networks (RNNs) are used for each component of the model in order to generate synthetic data to improve classification accuracy for a highly imbalanced medical device dataset. In addition to the medical device dataset, we also evaluate the GAN-AE performance on two additional datasets and demonstrate the application of GAN-AE to a sequence-to-sequence task where both synthetic sequence inputs and sequence outputs must be generated. To evaluate the quality of the synthetic data, we train encoder-decoder models both with and without the synthetic data and compare the classification model performance. We show that a model trained with GAN-AE generated synthetic data outperforms models trained with synthetic data generated both with standard oversampling techniques such as SMOTE and Autoencoders as well as with state of the art GAN-based models

Compliance and Imperfect Intertemporal Carbon Trading

This paper examines three compliance mechanisms of the Kyoto Protocol: (i) the restoration rate, (ii) the commitment period reserve rule, and (iii) the suspension mechanism, all potentially constraining greenhouse gas emissions trading across time and space. The joint effect of these mechanisms on prices and costs is studied in a twoperiod model under various assumptions about the competitiveness of the permit market and US participation. The analytical results indicate that the restoration rate can make discounted permit prices decrease over time. With the commitment period reserve, marginal costs may not only be lower, but also higher than the permit prices. The suspension rule will under quite general circumstances not affect prices and costs; only shift non-compliance from future sellers to future buyers. The numerical results suggest that with imperfect permit markets and non-participation of the US in the Kyoto Protocol in 2010, none of the three rules becomes binding.compliance; market power; emissions trading; Kyoto Protocol

Emergence and disappearance of micro-arcsecond structure in the scintillating quasar J1819+3845

The 4.8 GHz lightcurves of the scintillating intra-day variable quasar J1819+3845 during 2004-5 exhibit sharp structure, down to a time scale of 15 minutes, that was absent from lightcurves taken prior to this period and from the 2006 lightcurves. Analysis of the lightcurve power spectra show that the variations must be due to the emergence of new structure in the source. The power spectra yield a scattering screen distance of 3.8 +/- 0.3 pc for a best-fit v_ISS=59 +/- 0.5 km/s or 2.0 +/- 0.3 pc for the scintillation velocity reported by Dennett-Thorpe & de Bruyn (2003). The turbulence is required to be exceptionally turbulent, with C_N^2 > 0.7 Delta L_pc^{-1} m^{-20/3} for scattering material of thickness Delta L_{pc} pc along the ray path. The 2004 power spectrum can be explained in terms of a double source with a component separation 240 +/- 15 microas in 2004.Comment: MNRAS Lett (accepted), version with high-resolution figures at http://www.astro.caltech.edu/~jpm/MdB1819.pd

Tests of new instrument for measuring Dublin Descriptors

In the summer of 2007 a new instrument was developed which aimed at providingan operationalisation of the Dublin descriptors (Appendix 1). Special attention waspaid thereby to the so-called ‘anchor problem’ inherent in most self-assessments:the lack of an objective frame of reference against which different respondents canassess their own level of competence.The instrument consists of a combination of general and specific items. First of alla general item was formulated for each of the 5 Dublin descriptors. The generalitems were formulated in such a way as to match the original descriptors as closelyas possible. Anchors were developed for each of these items which correspond tojunior college, bachelors and masters levels. For example, for the item“communication” the junior college level was indicated by the anchor “is able totransmit information”, the bachelors level by "is able to communicate ideas andtransmit solutions” and the master level by “is able to communicate conclusionsand the knowledge, motivations and considerations that underlie these conclusionsin a convincing manner”. The anchors for the bachelors and masters level arederived more or less directly from the Dublin descriptors, and those for the juniorcollege level are based on the European Qualification Framework. For practicalreasons it was decided not to develop anchors for the PhD level. The anchors wereplaced in a scale ranging from 1 to 8, with the junior college level being assigned ascale value of 2, the bachelors level the value 5 and the masters level the value 7.This allowed respondents the option of choosing a level above masters level orbelow junior college level if they find that appropriate. The distances betweenjunior college, bachelors and masters level approximates the mean differences inyears of education corresponding to each level.labour market entry and occupational careers;

The effect of service time variability on maximum queue lengths in M^X/G/1 queues

We study the impact of service-time distributions on the distribution of the maximum queue length during a busy period for the M^X/G/1 queue. The maximum queue length is an important random variable to understand when designing the buffer size for finite buffer (M/G/1/n) systems. We show the somewhat surprising result that for three variations of the preemptive LCFS discipline, the maximum queue length during a busy period is smaller when service times are more variable (in the convex sense).Comment: 12 page

Exploring assessment of medical students\u27 competencies in pain medicine - A review

Introduction: Considering the continuing high prevalence and public health burden of pain, it is critical that medical students are equipped with competencies in the field of pain medicine. Robust assessment of student expertise is integral for effective implementation of competency-based medical education. Objective: The aim of this review was to describe the literature regarding methods for assessing pain medicine competencies in medical students. Method: PubMed, Medline, EMBASE, ERIC, and Google Scholar, and BEME data bases were searched for empirical studies primarily focusing on assessment of any domain of pain medicine competencies in medical students published between January 1997 and December 2016. Results: A total of 41 studies met the inclusion criteria. Most assessments were performed for low-stakes summative purposes and did not reflect contemporary theories of assessment. Assessments were predominantly undertaken using written tests or clinical simulation methods. The most common pain medicine education topics assessed were pain pharmacology and the management of cancer and low-back pain. Most studies focussed on assessment of cognitive levels of learning as opposed to more challenging domains of demonstrating skills and attitudes or developing and implementing pain management plans. Conclusion: This review highlights the need for more robust assessment tools that effectively measure the abilities of medical students to integrate pain-related competencies into clinical practice. A Pain Medicine Assessment Framework has been developed to encourage systematic planning of pain medicine assessment at medical schools internationally and to promote continuous multidimensional assessments in a variety of clinical contexts based on well-defined pain medicine competencies