Publications

International Policy Coordination: The Long View

This paper places current efforts at international economic policy coordination in historical perspective. It argues that successful cooperation is most likely in four sets of circumstances. First, when it centers on technical issues. Second, when cooperation is institutionalized - when procedures and precedents create presumptions about the appropriate conduct of policy and reduce the transactions costs of reaching an agreement. Third, when it is concerned with preserving an existing set of policies and behaviors (when it is concerned with preserving a policy regime). Fourth, when it occurs in the context of broad comity among nations. These points are elaborated through a review of 150 years of historical experience and then used to assess the scope for cooperative responses to the current economic crisis.

Leveling the cost and carbon footprint of circular polymers that are chemically recycled to monomer

While not yet competitive with commodity polymers, PDKs are recycled to monomer at lower cost and emissions than virgin resins.

CCDC 1469636: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Customizable Routing with Declarative Queries

To meet the demands of new Internet applications, recent work argues for giving end-hosts more control over routing. To achieve this goal, we propose the use of a recursive query language, which allows users to define their own routing protocols. Recursive queries can be used to express a large variety of route requests such as the k shortest paths, shortest paths that avoid (or include) a given set of nodes and least-loaded paths. We show that these queries can be e#ciently implemented in the network, and in the simple case when all users request shortest paths, the communication overhead of our solution is similar to that incurred by a distance vector protocol. In addition, when only a subset of nodes issue the same query, the communication cost can be further lowered using automatic query optimization techniques -- suggesting that declarative queries and automatic optimization are important in this domain. Finally, we outline the main challenges faced by our proposal, focusing on the expressiveness and e#ciency of our proposal.

CCDC 739219: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A complete classification of memristor devices

Several physical and mathematical models have been proposed to describe all 2-terminal non-volatile memory devices based on resistance switching (i.e. memristors), regardless of the device material and physical operating mechanisms. A complete and precise classification of memristor, including memcapacitor and meminductors as well, is instrumental in matching model parameters to physical phenomena and in boosting applications of memristors in unconventional computing systems. The aim of the paper is to provide a theoretical approach to the various classes of mem-devices (i.e. memristors, memcapacitors and meminductors) as nonlinear dynamical systems whose characteristic curves (i.e. dynamic characteristics) are pinched at the origin when driven by bipolar excitations. This theory provides a practical tool to describe mem-devices developed for non-volatile memory applications and neuromorphic systems.

CCDC 1020609: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Deblurring of images by cellular neural networks with applications to microscopy

In this paper it is shown how the Cellular Neural Network (CNN) can be used to perform image and volume deblurring, with particular emphases on applications to microscopy. We discuss the basic linear theory of the CNN including issues of stability and template size. It is observed that a CNN with a small template can be used to implement an Infinite Impulse Response filter. It is then shown how general deblurring problems can be addressed with a CNN when the blurring operator is known. The proposed application is to solve the basic 3-D confocal image reconstruction task about the form of the blurring operator, confocal behavior in microscope images can be obtained with only 3-5 acquired image planes. In addition, the stored program capability of the CNN Universal Machine would provide integration of several image processing and detection tasks in the same architecture.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Semi-synthetic artemisinin: a model for the use of synthetic biology in pharmaceutical development

Bridging Materials and Pressure Gaps in Surface Science and Heterogeneous Catalysis

Supernovae 2010an, 2010ao, 2010au, and 2010al

WSe2 light-emitting diode coupled to optical bowtie antennas

Medicare Accountable Care Organizations of Diverse Structures Achieve Comparable Quality and Cost Performance

Objective To examine whether an empirically derived taxonomy of Accountable Care Organizations ( ACO s) is associated with quality and spending performance among patients of ACO s in the Medicare Shared Savings Program ( MSSP ). Data Sources Three waves of the National Survey of ACO s and corresponding publicly available Centers for Medicare &amp; Medicaid Services performance data for NSACO respondents participating in the MSSP ( N = 204); SK &amp;A Office Based Physicians Database from Quintiles IMS . Study Design We compare the performance of three ACO types (physician‐led, integrated, and hybrid) for three domains: quality, spending, and likelihood of achieving savings. Sources of performance variation within and between ACO types are compared for each performance measure. Principal Findings There is greater heterogeneity within ACO types than between ACO types. There were no consistent differences in quality by ACO type, nor were there differences in likelihood of achieving savings or overall spending per‐person‐year. There was evidence for higher spending on physician services for physician‐led ACO s. Conclusions ACO s of diverse structures perform comparably on core MSSP quality and spending measures. CMS should maintain its flexibility and continue to support participation of diverse ACO s. Future research to identify modifiable organizational factors that account for performance variation within ACO types may provide insight as to how best to improve ACO performance based on organizational structure and ownership.

How to Build a Memristive Integrate-and-Fire Model for Spiking Neuronal Signal Generation

We present and experimentally validate two minimal compact memristive models for spiking neuronal signal generation using commercially available low-cost components. The first neuron model is called the Memristive Integrate-and-Fire (MIF) model, for neuronal signaling with two voltage levels: the spike-peak, and the rest-potential. The second model MIF2 is also presented, which promotes local adaptation by accounting for a third refractory voltage level during hyperpolarization. We show both compact models are minimal in terms of the number of circuit elements and integration area. Using the MIF and MIF2 models, we postulate the design of a memristive solid-state brain with an estimation of its surface area and power consumption. Analytical projections show that a memristive solid-state brain could be realized within (i) the surface area of the median human brain, 2,400cm(2), (ii) the same volume of the median human brain, and (iii) a total power budget of approximately 20 W using a 3.5 nm technology. Distinct from the past decade of memristive neuron literature, our benchmarks are attained using generic commercially available memristors that are reproducible using off-the-shelf components. We expect this work can promote more experimental demonstrations of memristive circuits that do not rely on prohibitively expensive fabrication processes.

Discovering the Nature of Dark Energy: Towards Better Distances from Type Ia Supernovae -- Final Technical Report

Type Ia supernovae (SNe Ia; exploding white-dwarf stars) were the key to the Nobel-worthy 1998 discovery and subsequent verification that the expansion of the Universe is accelerating, driven by the effects of dark energy. Understanding the nature of this mysterious, yet dominant, component of the Universe is at the forefront of research in cosmology and fundamental physics. SNe Ia will continue to play a leading role in this enterprise, providing precise cosmological distances that improve constraints on the nature of dark energy. However, for this effort to succeed, we need to more thoroughly understand relatively nearby SNe Ia, because our conclusions come only from comparisons between them and distant (high-redshift) SNe Ia. Thus, detailed studies of relatively nearby SNe Ia are the focus of this research program. Many interesting results were obtained during the course of this project; these were published in 32 refereed research papers that acknowledged the grant. A major accomplishment was the publication of supernova (SN) rates derived from about a decade of operation of the Lick Observatory Supernova Search (LOSS) with the 0.76-meter Katzman Automatic Imaging Telescope (KAIT). We have determined the most accurate rates for SNe of different types in large, nearby galaxies in the present-day Universe, and these can be compared with SN rates far away (and hence long ago in the past) to set constraints on the types of stars that explode. Another major accomplishment was the publication of the light curves (brightness vs. time) of 165 SNe Ia, along with optical spectroscopy of many of these SNe as well as other SNe Ia, providing an extensive, homogeneous database for detailed studies. We have conducted intensive investigations of a number of individual SNe Ia, including quite unusual examples that allow us to probe the entire range of SN explosions and provide unique insights into these objects and the stars before they explode. My team's studies have also led to the identification of subsamples of SNe Ia that can be used to provide the most reliable cosmological distances, and we developed ways to deal with the dust that makes SNe Ia appear fainter than they really are. Using the KAIT/LOSS sample, we produced an excellent Hubble diagram (galaxy recession speed vs. distance), accurately showing the expansion of the Universe. Even smaller scatter was achieved when spectroscopic characteristics were taken into account. Another high-quality Hubble diagram was constructed with SNe Ia from the Sloan Digital Sky Survey (SDSS). These Hubble diagrams provide useful new constraints on the nature of the dark energy that is accelerating the expansion of the Universe. As an added bonus of our research, we also studied core-collapse SNe, which differ fundamentally from SNe Ia.

Sleep problems and depressive symptoms in toddlers and 8‐year‐old children: A longitudinal study

Abstract Sleep and depression are interlinked throughout the lifespan, but very few studies have examined the directionality of the sleep–depression link in children. The aim of the current study was to prospectively examine the bidirectional association between sleep problems and internalizing problems and depressive symptoms in toddlers and children aged 1.5 and 8 years. Data stem from the large ongoing population‐based longitudinal study, the Norwegian Mother, Father and Child Cohort Study, recruited from October 1999 to July 2009. A total of 35,075 children were included. Information on sleep duration, nocturnal awakenings and internalizing problems (Child Behaviour Checklist) was provided by the mothers at 1.5 years, whereas data on sleep duration and depressive symptoms (Short Mood and Feelings Questionnaire) were provided by the mothers when the children were 8 years old. Odds ratios (ORs) were calculated using logistic regression analyses. After accounting for previous internalizing problems, short sleep duration (≤10 hr) and frequent (≥3) nightly awakenings at 1.5 years predicted the development of depressive symptoms at 8 years of age (adjusted OR = 1.28; 95% confidence interval [CI] 1.08–1.51, and adjusted OR = 1.27, 95% CI 1.08–1.50, respectively). Also, internalizing problems at 1.5 years predicted onset of later short sleep duration (adjusted OR = 1.83, 95% CI 1.32–2.54) after accounting for early sleep problems. This prospective study demonstrated a bidirectional association between sleep and internalizing/depressive symptoms from toddlerhood to middle childhood. Intervention studies are needed to examine whether targeting either of these problems at this early age may prevent onset of the other.

Metalloallostery and Transition Metal Signaling: Bioinorganic Copper Chemistry Beyond Active Sites

Abstract Transition metal chemistry is essential to life, where metal binding to DNA, RNA, and proteins underpins all facets of the central dogma of biology. In this context, metals in proteins are typically studied as static active site cofactors. However, the emergence of transition metal signaling, where mobile metal pools can transiently bind to biological targets beyond active sites, is expanding this conventional view of bioinorganic chemistry. This Minireview focuses on the concept of metalloallostery, using copper as a canonical example of how metals can regulate protein function by binding to remote allosteric sites (e.g., exosites). We summarize advances in and prospects for the field, including imaging dynamic transition metal signaling pools, allosteric inhibition or activation of protein targets by metal binding, and metal‐dependent signaling pathways that underlie nutrient vulnerabilities in diseases spanning obesity, fatty liver disease, cancer, and neurodegeneration.