An Instantiation-Based Approach for Solving Quantified Linear Arithmetic

This paper presents a framework to derive instantiation-based decision procedures for satisfiability of quantified formulas in first-order theories, including its correctness, implementation, and evaluation. Using this framework we derive decision procedures for linear real arithmetic (LRA) and linear integer arithmetic (LIA) formulas with one quantifier alternation. Our procedure can be integrated into the solving architecture used by typical SMT solvers. Experimental results on standardized benchmarks from model checking, static analysis, and synthesis show that our implementation of the procedure in the SMT solver CVC4 outperforms existing tools for quantified linear arithmetic

Analyzing financial sectors in transition : with special reference to the Former Soviet Union

This paper proposes a framework for analyzing the evolution of financial sectors in economies transiting from command to market structures. Most commentators have tended to regard this"Transition"as an undifferentiated period to be traversed as rapidly as possible. In doing so they ignore the increasing evidence that the Transition can be an extended, even enduring, state of the world, resulting from a complex interaction of economic, political, cultural and psychological factors. As such, it can and does generate incentives which fundamentally distort the behavior of economic agents in unpredictable ways. The authors argue that one result of ignoring the true messiness of the Transition is that the analysis and policy recommendations offered to governments can be flawed and often provide conclusions which are odds with the reality on the ground. The paper discusses this concern and proposes a simple analytical framework both for focusing on the Transition itself and also for use in defining and evaluating possible public policy interventions for the banking sector. This paper is organized as follows. Section II sketches the main shortcomings of the traditional analyses of the financial sector in transition - particularly the limitations of current thinking on the sequencing of financial sector reforms. Section III introduces and elaborates on the basic framework proposed. Section IV uses the framework to distill some simple but important propositions about transition banking. Section V provides an initial qualitative test of the framework, by using it as a lens through which to view some of the characteristics of transition banks which we have observed. It shows that behavior patterns which, at first glance, seem curious and counterproductive, do indeed have a rational explanation when viewed in relation to the analytical framework we propose. Section VI applies the proposed analytical approach to assess the appropriateness of various interventions -- especially those which have proved popular in the World Bank -- to support the financial sector transition. Two Annexes then elaborate particular aspects of the analysis. Annex 1 assesses how our analysis might recondition thinking about the appropriate regulatory and supervisory structures for transition banking. Annex 2 provides some initial empirical results based on our proposed framework of analysis.Environmental Economics&Policies,Banks&Banking Reform,Financial Intermediation,Payment Systems&Infrastructure,Labor Policies,Financial Intermediation,Environmental Economics&Policies,Insurance&Risk Mitigation,Financial Crisis Management&Restructuring,Banks&Banking Reform

High-Speed, Photon Counting CCD Cameras for Astronomy

The design of electron multiplying CCD cameras require a very different approach from that appropriate for slow scan CCD operation. This paper describes the main problems in using electron multiplying CCDs for high-speed, photon counting applications in astronomy and how these may be substantially overcome. With careful design it is possible to operate the E2V Technologies L3CCDs at rates well in excess of that claimed by the manufacturer, and that levels of clock induced charge dramatically lower than those experienced with commercial cameras that need to operate at unity gain. Measurements of the performance of the E2V Technologies CCD201 operating at 26 MHz will be presented together with a guide to the effective reduction of clock induced charge levels. Examples of astronomical results obtained with our cameras are presented.Comment: 11 pages, 5 figure

High-resolution imaging and spectroscopy in the visible from large ground-based telescopes with natural guide stars

Near-diffraction limited imaging and spectroscopy in the visible on large (8-10 meter) class telescopes has proved to be beyond the capabilities of current adaptive optics technologies, even when using laser guide stars. The need for high resolution visible imaging in any part of the sky suggests that a rather different approach is needed. This paper describes the results of simulations, experiments and astronomical observations that show that a combination of low order adaptive optic correction using a 4-field curvature sensor and fast Lucky Imaging strategies with a photon counting CCD camera systems should deliver 20-25 milliarcsecond resolution in the visible with reference stars as faint as 18.5 magnitude in I band on large telescopes. Such an instrument may be used to feed an integral field spectrograph efficiently using configurations that will also be described.Comment: 8 pages, 3 figure

Review: Delivering mental health support within schools and colleges – a thematic synthesis of barriers and facilitators to implementation of indicated psychological interventions for adolescents

Background: Increasing the role of schools and colleges in the provision of mental health services for young people has the potential to improve early intervention and access to treatment. We aimed to understand what factors influence the successful implementation of indicated psychological interventions within schools and colleges to help guide increased provision of mental health support within education settings. Methods: Systematic search for studies that have reported barriers or facilitators to the implementation of indicated interventions for adolescent emotional disorders delivered within schools and further education/sixth form colleges (CRD42018102830). Databases searched were EMBASE, MEDLINE, PsycINFO, CINAHL, British Nursing Index, ASSIA, ERIC and British Education Index. A thematic synthesis of factors reported to impact implementation was conducted. Results: Two thousand five hundred and sixty-nine records and 177 full texts were screened. Fifty studies were identified for inclusion, all of which were of school-based interventions. Eleven analytic themes were developed encompassing intervention characteristics, organisational capacity, training and technical assistance, provider characteristics and community-level factors. Findings indicate the need to select appropriate interventions, consider logistical challenges of the school context and provide training and supervision to enable staff to deliver interventions with fidelity. However, structural and environmental support is required for these facilitators to have the greatest impact on successful implementation. Conclusions: Implementing indicated school-based mental health interventions is challenging. Those involved in planning school-based mental health initiatives must be alert to the impact of factors on multiple interacting levels. There is a lack of research on implementing mental health support within further education and sixth form colleges

Rapid Circumstellar Disk Evolution and an Accelerating Star Formation Rate in the Infrared Dark Cloud M17 SWex

We present a catalog of 840 X-ray sources and first results from a 100 ks Chandra X-ray Observatory imaging study of the filamentary infrared dark cloud G014.225$-$00.506, which forms the central regions of a larger cloud complex known as the M17 southwest extension (M17 SWex). In addition to the rich population of protostars and young stellar objects with dusty circumstellar disks revealed by Spitzer Space Telescope archival data, we discover a population of X-ray-emitting, intermediate-mass pre--main-sequence stars (IMPS) that lack infrared excess emission from circumstellar disks. We model the infrared spectral energy distributions of this source population to measure its mass function and place new constraints on the inner dust disk destruction timescales for 2-8 $M_{\odot}$ stars. We also place a lower limit on the star formation rate (SFR) and find that it is quite high ($\dot{M}\ge 0.007~M_{\odot}$ yr$^{-1}$), equivalent to several Orion Nebula Clusters in G14.225$-$0.506 alone, and likely accelerating. The cloud complex has not produced a population of massive, O-type stars commensurate with its SFR. This absence of very massive (${\ge}20~M_{\odot}$) stars suggests that either (1) M17 SWex is an example of a distributed mode of star formation that will produce a large OB association dominated by intermediate-mass stars but relatively few massive clusters, or (2) the massive cores are still in the process of accreting sufficient mass to form massive clusters hosting O stars.Comment: 29 pages, 9 figures, accepted to Ap