Heterogeneous multireference alignment: a single pass approach

Multireference alignment (MRA) is the problem of estimating a signal from many noisy and cyclically shifted copies of itself. In this paper, we consider an extension called heterogeneous MRA, where $K$ signals must be estimated, and each observation comes from one of those signals, unknown to us. This is a simplified model for the heterogeneity problem notably arising in cryo-electron microscopy. We propose an algorithm which estimates the $K$ signals without estimating either the shifts or the classes of the observations. It requires only one pass over the data and is based on low-order moments that are invariant under cyclic shifts. Given sufficiently many measurements, one can estimate these invariant features averaged over the $K$ signals. We then design a smooth, non-convex optimization problem to compute a set of signals which are consistent with the estimated averaged features. We find that, in many cases, the proposed approach estimates the set of signals accurately despite non-convexity, and conjecture the number of signals $K$ that can be resolved as a function of the signal length $L$ is on the order of $\sqrt{L}$.Comment: 6 pages, 3 figure

Borderline Personality Features and Integration of Positive and Negative Thoughts About Significant Others

Taking the bad with the good is a necessity of life, and people who readily integrate thoughts of their loved one’s flaws with thoughts of their more positive attributes maintain more stable, satisfying relationships. Borderline personality disorder, however, is often characterized by interpersonal perceptions that fluctuate between extremes of good and bad. We used a timed judgment task to examine information processing about significant others in individuals high in borderline personality features relative to healthy individuals and those high in avoidant personality features. In Study 1, when judging traits of a liked significant other, same-valence facilitation by negative primes (judging negative traits faster than positive traits after a negative prime) was significantly stronger in the borderline features group than the other two groups, and was inversely associated with self-reports of integrated thoughts about significant others. In contrast, same-valence facilitation by positive primes (judging positive traits faster than negative traits after a positive prime) was significantly stronger in the avoidant features group than the other two groups, and inversely associated with self-esteem. No between-group differences in same-valence facilitation were statistically significant when participants judged traits of disliked significant others, liked foods, and disliked foods. In Study 2, same-valence facilitation by negative primes when judging traits of a liked significant other was significantly associated with less integrated positive/negative thoughts about that person in a 12-day diary. These results identify an implicit information-processing pattern relevant to interpersonal difficulties in borderline personality disorder

Financial markets and the adjustment to higher oil prices

A great deal has been written on the actual and potential effects of the oil price increase on world financial markets, but relatively little emphasis has been placed on the role played by financial markets in the adjustment of the energy markets themselves. This paper explores the linkages betwee

Accommodation in the international capital markets and the recycling of oil funds

Prepared in association with the Sloan School of Management and the Dept. of Economic

The international finance aspects of OPEC : an informational note

National Science Foundation Grant no. SIA75-0073

Structure of amyloid-β (20-34) with Alzheimer's-associated isomerization at Asp23 reveals a distinct protofilament interface.

Amyloid-β (Aβ) harbors numerous posttranslational modifications (PTMs) that may affect Alzheimer's disease (AD) pathogenesis. Here we present the 1.1 Å resolution MicroED structure of an Aβ 20-34 fibril with and without the disease-associated PTM, L-isoaspartate, at position 23 (L-isoAsp23). Both wild-type and L-isoAsp23 protofilaments adopt β-helix-like folds with tightly packed cores, resembling the cores of full-length fibrillar Aβ structures, and both self-associate through two distinct interfaces. One of these is a unique Aβ interface strengthened by the isoaspartyl modification. Powder diffraction patterns suggest a similar structure may be adopted by protofilaments of an analogous segment containing the heritable Iowa mutation, Asp23Asn. Consistent with its early onset phenotype in patients, Asp23Asn accelerates aggregation of Aβ 20-34, as does the L-isoAsp23 modification. These structures suggest that the enhanced amyloidogenicity of the modified Aβ segments may also reduce the concentration required to achieve nucleation and therefore help spur the pathogenesis of AD

Multiplexing for Oxidative Bisulfite Sequencing (oxBS-seq).

DNA modifications, especially methylation, are known to play a crucial part in many regulatory processes in the cell. Recently, 5-hydroxymethylcytosine (5hmC) was discovered, a DNA modification derived as an intermediate of 5-methylcytosine (5mC) oxidation. Efforts to gain insights into function of this DNA modification are underway and several methods were recently described to assess 5hmC levels using sequencing approaches. Here we integrate adaptation based multiplexing and high-efficiency library prep into the oxidative Bisulfite Sequencing (oxBS-seq) workflow reducing the starting amount and cost per sample to identify 5hmC levels genome-wide

Paper Session II-A - ISOBUS A Faster, Better, Cheaper Tool for Space Flight Experiments

Space exploration and related investigations have been suffering from programmatic inefficiencies inherent to customized projects. One-of-a-kind space investigations such as experiments, installations, platforms, and missions all lack the profit-driven architectures and money-making methodologies that characterize commercial enterprise. The foundation of long-tenm commercial success is in the smart and efficient utilization of capital investment. An enterprise that throws away its tools, its infrastructure, its expertise, and its capital, every time it completes a project is not likely to be able to afford to do so again and again. When resources are scarce, one must utilize them efficiently. Proven commercial methodologies such as standardization, mass production, miniaturization, modular interchangeability, and reusability . of tools, facilities, and resources are the principal techniques by which products can be created faster-better-cheaper. Commercial investigators in intensely competitive fields, such as biotechnology, have successfully applied these principles to their experimental setups, tools, and support systems. We must similarly employ commercial principles if we are to survive the expensive challenge of future space exploration. This paper introduces a faster-bettercheaper\u27\u27 approach for space investigators. The approach employs a tool called ISOBUS

Large Deviations Behavior of the Logarithmic Error Probability of Random Codes

This work studies the deviations of the error exponent of the constant composition code ensemble around its expectation, known as the error exponent of the typical random code (TRC). In particular, it is shown that the probability of randomly drawing a codebook whose error exponent is smaller than the TRC exponent is exponentially small; upper and lower bounds for this exponent are given, which coincide in some cases. In addition, the probability of randomly drawing a codebook whose error exponent is larger than the TRC exponent is shown to be double–exponentially small; upper and lower bounds to the double–exponential exponent are given. The results suggest that codebooks whose error exponent is larger than the error exponent of the TRC are extremely rare. The key ingredient in the proofs is a new large deviations result of type class enumerators with dependent variables