Rank Structure Research Articles

Low-Information Voting: Evidence From Instant-Runoff Elections

How do voters make decisions in low-information contests? Although some research has looked at low-information voter decision making, scant research has focused on data from actual ballots cast in low-information elections. We focus on three 2008 Pierce County (Washington) Instant-Runoff Voting (IRV) elections. Using individual-level ballot image data, we evaluate the structure of individual rankings for specific contests to determine whether partisan cues underlying partisan rankings are correlated with choices made in nonpartisan races. This is the first time that individual-level data from real elections have been used to evaluate the role of partisan cues in nonpartisan races. We find that, in partisan contests, voters make avid use of partisan cues in constructing their preference rankings, rank-ordering candidates based on the correspondence between voters’ own partisan preferences and candidates’ reported partisan affiliation. However, in nonpartisan contests where candidates have no explicit partisan affiliation, voters rely on cues other than partisanship to develop complete candidate rankings.

Tensor surgery and tensor rank

We introduce a method for transforming low-order tensors into higher-order tensors and apply it to tensors defined by graphs and hypergraphs. The transformation proceeds according to a surgery-like procedure that splits vertices, creates and absorbs virtual edges and inserts new vertices and edges. We show that tensor surgery is capable of preserving the low rank structure of an initial tensor decomposition and thus allows to prove nontrivial upper bounds on tensor rank, border rank and asymptotic rank of the final tensors. We illustrate our method with a number of examples. Tensor surgery on the triangle graph, which corresponds to the matrix multiplication tensor, leads to nontrivial rank upper bounds for all odd cycle graphs, which correspond to the tensors of iterated matrix multiplication. In the asymptotic setting we obtain upper bounds in terms of the matrix multiplication exponent $\omega$ and the rectangular matrix multiplication parameter $\alpha$. These bounds are optimal if $\omega$ equals two. We also give examples that illustrate that tensor surgery on general graphs might involve the absorption of virtual hyperedges and we provide an example of tensor surgery on a hypergraph. Besides its relevance in algebraic complexity theory, our work has applications in quantum information theory and communication complexity.

Some new computable structures of high rank

We give several new examples of computable structures of high Scott rank. For earlier known computable structures of Scott rank ω 1 C K \omega _1^{CK} , the computable infinitary theory is ℵ 0 \aleph _0 -categorical. Millar and Sacks asked whether this was always the case. We answer this question by constructing an example whose computable infinitary theory has non-isomorphic countable models. The standard known computable structures of Scott rank ω 1 C K + 1 \omega _1^{CK}+1 have infinite indiscernible sequences. We give two constructions with no indiscernible ordered triple.

Finding a stable matching under type-specific minimum quotas

In matching problems with minimum and maximum type-specific quotas, there may not exist a stable (i.e., fair and non-wasteful) assignment (Ehlers et al., 2014). This paper investigates the structure of schools' priority rankings which guarantees stability. First, we show that there always exists a fair and non-wasteful assignment if for each type of students, schools have common priority rankings over a certain number of bottom students. Next, we show that the pairwise version of this condition characterizes the maximal domain of two schools' priority rankings over same type students to guarantee the existence of stable assignments. To prove the existence theorem, we propose a new mechanism Deferred Acceptance with Precedence Lists (DAPL), which is feasible, non-wasteful, strictly PL-fair and group strategy-proof for any priority rankings. Strict PL-fairness is weaker than fairness, but DAPL satisfies fairness under our sufficient condition. We also show that there is no strategy-proof mechanism that Pareto dominates DAPL whenever the outcome of DAPL is Pareto dominated by a stable assignment.

Comparative Evaluation of Three Schaake Shuffle Schemes in Postprocessing GEFS Precipitation Ensemble Forecasts

Abstract Natural weather systems possess certain spatiotemporal variability and correlations. Preserving these spatiotemporal properties is a significant challenge in postprocessing ensemble weather forecasts. To address this challenge, several rank-based methods, the Schaake Shuffle and its variants, have been developed in recent years. This paper presents an extensive assessment of the Schaake Shuffle and its two variants. These schemes differ in how the reference multivariate rank structure is established. The first scheme (SS-CLM), an implementation of the original Schaake Shuffle method, relies on climatological observations to construct rank structures. The second scheme (SS-ANA) utilizes precipitation event analogs obtained from a historical archive of observations. The third scheme (SS-ENS) employs ensemble members from the Global Ensemble Forecast System (GEFS). Each of the three schemes is applied to postprocess precipitation ensemble forecasts from the GEFS for its first three forecast days over the mid-Atlantic region of the United States. In general, the effectiveness of these schemes depends on several factors, including the season (or precipitation pattern) and the level of gridcell aggregation. It is found that 1) the SS-CLM and SS-ANA behave similarly in spatial and temporal correlations; 2) by a measure for capturing spatial variability, the SS-ENS outperforms the SS-ANA, which in turn outperforms the SS-CLM; and 3), overall, the SS-ANA performs better than the SS-CLM. The study also reveals that it is important to choose a proper size for the postprocessed ensembles in order to capture extreme precipitation events.

On the Species Structure of a Competitive Marine Community

Some examples of marine animal and plant communities with a structure determined by competitive inter-species relationships are discussed. It has been shown that the ranked species structure of these communities obeys a geometric progression, whose coefficient does not differ significantly from the constant exp(–1) = 0.368. A relationship between a certain parameter of this progression and the species diversity of a community has been found.

Hypercube related polytopes

Body centered structures are used as seeds for a variety of structures of rank 3 and higher. Propellane based structures are introduced and their design and topological properties are detailed.

The typological effects of ABC constraint definitions

Recent work under the theoretical banner of Agreement by Correspondence (ABC) has produced a variety of different – and sometimes contradictory – formulations of the constraints central to this framework. In OT, the effects of such definitional choices come out in the factorial typologies they predict. Yet knowing what languages a theoretical system derives is insufficient unless we know why it does so. This requires analysis of the internal ranking structures of the typology itself. This paper compares the typologies produced under different proposed modifications to the main ABC constraints. We analyse the typologies in Property Theory, a theory of typological organisation in OT. Our analyses show that all variations have a common core structure, and that differences in their factorial typologies reduce to differences in how this common structure expands and iterates for different features. This allows for precise delineation of how and why different ABC constraint definitions affect typologies.

Simple motion correction strategy reduces respiratory-induced motion artifacts for k-t accelerated and compressed-sensing cardiovascular magnetic resonance perfusion imaging

BackgroundCardiovascular magnetic resonance (CMR) stress perfusion imaging provides important diagnostic and prognostic information in coronary artery disease (CAD). Current clinical sequences have limited temporal and/or spatial resolution, and incomplete heart coverage. Techniques such as k-t principal component analysis (PCA) or k-t sparcity and low rank structure (SLR), which rely on the high degree of spatiotemporal correlation in first-pass perfusion data, can significantly accelerate image acquisition mitigating these problems. However, in the presence of respiratory motion, these techniques can suffer from significant degradation of image quality. A number of techniques based on non-rigid registration have been developed. However, to first approximation, breathing motion predominantly results in rigid motion of the heart. To this end, a simple robust motion correction strategy is proposed for k-t accelerated and compressed sensing (CS) perfusion imaging.MethodsA simple respiratory motion compensation (MC) strategy for k-t accelerated and compressed-sensing CMR perfusion imaging to selectively correct respiratory motion of the heart was implemented based on linear k-space phase shifts derived from rigid motion registration of a region-of-interest (ROI) encompassing the heart. A variable density Poisson disk acquisition strategy was used to minimize coherent aliasing in the presence of respiratory motion, and images were reconstructed using k-t PCA and k-t SLR with or without motion correction. The strategy was evaluated in a CMR-extended cardiac torso digital (XCAT) phantom and in prospectively acquired first-pass perfusion studies in 12 subjects undergoing clinically ordered CMR studies. Phantom studies were assessed using the Structural Similarity Index (SSIM) and Root Mean Square Error (RMSE). In patient studies, image quality was scored in a blinded fashion by two experienced cardiologists.ResultsIn the phantom experiments, images reconstructed with the MC strategy had higher SSIM (p < 0.01) and lower RMSE (p < 0.01) in the presence of respiratory motion. For patient studies, the MC strategy improved k-t PCA and k-t SLR reconstruction image quality (p < 0.01). The performance of k-t SLR without motion correction demonstrated improved image quality as compared to k-t PCA in the setting of respiratory motion (p < 0.01), while with motion correction there is a trend of better performance in k-t SLR as compared with motion corrected k-t PCA.ConclusionsOur simple and robust rigid motion compensation strategy greatly reduces motion artifacts and improves image quality for standard k-t PCA and k-t SLR techniques in setting of respiratory motion due to imperfect breath-holding.

Utilizing reliability modeling to analyze United States Air Force officer retention

Considered thousands of officer personnel records form the United States Air Force.Models for retention over several dozen career fields.Retention models focused on a 20-year time frame.Developed methods to combine retention models.Devised new metric for managerial use that provides insights into career fields requiring special attention. The United States Air Force organizes its workforce around rank structure and work specialty codes (Air Force Specialty Codes (AFSCs)). Unlike civilian organizations, all active duty Air Force personnel start at the entry level ranks. The challenge is to develop and manage personnel to fill a variety of skill sets at a variety of ranks over a 2030year planning horizon. The Air Force uses sustainment lines to accomplish many of its manpower management goals. However, the current methodology for developing these sustainment lines is not statistically defensible based on the actual retention data and does not provide management a means to identify specialty codes of concern. Leveraging methods from reliability theory, we utilize survivability functions constructed from historical retention data to develop and demonstrate a statistically defensible methodology for creating the sustainment lines at the core of the Air Force personnel management system and provide a tool for managers to focus attention on potential workforce problem areas.

Variational Gaussian approximation for Poisson data

The Poisson model is frequently employed to describe count data, but in a Bayesian context it leads to an analytically intractable posterior probability distribution. In this work, we analyze a variational Gaussian approximation to the posterior distribution arising from the Poisson model with a Gaussian prior. This is achieved by seeking an optimal Gaussian distribution minimizing the Kullback–Leibler divergence from the posterior distribution to the approximation, or equivalently maximizing the lower bound for the model evidence. We derive an explicit expression for the lower bound, and show the existence and uniqueness of the optimal Gaussian approximation. The lower bound functional can be viewed as a variant of classical Tikhonov regularization that penalizes also the covariance. Then we develop an efficient alternating direction maximization algorithm for solving the optimization problem, and analyze its convergence. We discuss strategies for reducing the computational complexity via low rank structure of the forward operator and the sparsity of the covariance. Further, as an application of the lower bound, we discuss hierarchical Bayesian modeling for selecting the hyperparameter in the prior distribution, and propose a monotonically convergent algorithm for determining the hyperparameter. We present extensive numerical experiments to illustrate the Gaussian approximation and the algorithms.

Novgorod Tartars in the Time of Troubles and after: Social Group Reconsolidation

The regional diversity of Muscovy, which was established in the second half of the 16th century, and attempts to describe it with the help of the emerging language of Muscovite bureaucracy was a way to construct the ranks that were later to become a specific feature of Muscovite society. The Novgorod lands were the first place where this language was created. Throughout the 16th century, the structure of ranks in the Novgorod lands became more diverse and complex. This article studies the restoration of a specific group of servicemen of Veliky Novgorod following the Time of Troubles and 1617, i. e. Muslim Tartars and the newly-baptised. Due to an immense decrease in the number of representatives of this and other categories of servicemen, the bureaucratic structure simplified. Very few Novgorod Muslim Tartars and newly-baptised kept their estates. Although different records kept referring to this special rank, it was mentioned together with all the other categories of servicemen in the same documents. Large numbers of the descendants of Novgorod Tartars changed their status and started receiving salaries on a regular basis, which made their status comparable to that of streltsy and artillerymen. For the purposes of comparison, the author refers to examples connected with former representatives of the group who, following the Treaty of Stolbovo, became subjects of the Kingdom of Sweden. Initially, i. e. until 1630, the Swedish administration kept references to this rank in its documents but as of the second generation of former Muscovite servicemen, their descendants were referred to as Bayors (Swedish baijorer), and almost all of them converted to Lutheranism. References to the Tartar descent of landowners can only be found in registries until the mid-17th century. The article considers the correspondence of the bureaucratic ranks to 17th-century social groups. In this context, it seems appropriate to consider Novgorod Tatars, as they were a group which was special both from the point of view of language and religion.

Low-Information Voting: Evidence from Instant-Runoff Elections

How do voters make decisions in low-information contests? Although some research has looked at low-information voter decision-making, scant research has focused on data from actual ballots cast in low-information elections. We focus on three 2008 Pierce County (Washington) Instant-Runoff Voting (IRV) elections. Using individual-level ballot image data, we evaluate the structure of individual rankings for specific contests to determine whether partisan cues underlying partisan rankings are correlated with choices made in nonpartisan races. This is the first time that individual-level data from real elections has been used to evaluate the role of partisan cues in nonpartisan races. We find that, in partisan contests, voters make avid use of partisan cues in constructing their preference rankings, rank-ordering candidates based on the correspondence between voters’ own partisan preferences and candidates’ reported partisan affiliation. However, in nonpartisan contests where candidates have no explicit partisan affiliation, voters rely on cues other than partisanship to develop complete candidate rankings.

Detecting Co-Movements in Noncausal Time Series

This paper introduces the notion of common noncausal features and proposes tools to detect them in multivariate time series models. We argue that the existence of co-movements might not be detected using the conventional stationary vector autoregressive (VAR) model as the common dynamics are present in the noncausal (i.e. forward-looking) component of the series. In particular, we show that the presence of a reduced rank structure allows to identify purely causal and noncausal VAR processes of order two and higher even in the Gaussian likelihood framework. Hence, usual test statistics and canonical correlation analysis can still be applied, where both lags and leads are used as instruments to determine whether the common features are present in either the backward- or forward-looking dynamics of the series. The proposed de finitions of co-movements also valid for the mixed causal-noncausal VAR, with the exception that an approximate non-Gaussian maximum likelihood estimator is necessary for these cases. This means however that one loses the bene fits of the simple tools proposed in this paper. An empirical analysis on European Brent and U.S. West Texas Intermediate oil prices illustrates the main fi ndings. Whereas we fail to fi nd any short run co-movements in a conventional causal VAR, they are detected in the growth rates of the series when considering a purely noncausal VAR.

СОЦІАЛЬНО-ПСИХОЛОГІЧНІ МЕХАНІЗМИ ФУНКЦІОНУВАННЯ ІМІДЖУ СУЧАСНОГО ЛІДЕРА В УМОВАХ СУЧАСНОГО ЕТАПУ РОЗВИТКУ УКРАЇНСЬКОГО СУСПІЛЬСТВА

The work is devoted to the psychological analysis of the features of the image of the leader at the present stage of development of the Ukrainian state. The need for psychological studies of the image is conditioned by the contradictions between the social practice of image functioning in different spheres of social life and the need for its theoretical reflection. Methods based on the means of social and psychological influence become significant. Among these tools, the image of the leader is essential. During the creation of his vision, the leader demonstrates the most attractive individual, personal, and professional qualities, learns to see them in themselves "from the side", is aware of his shortcomings, correlates his own characteristics with the standard of personality. In recent years, the concept of the image has firmly entered the information space. In most cases, the image is perceived by people like a specific value, which is associated with the success of certain activities, both individual and collective. Representatives of psychological science have increased their interest in the phenomenon of an image, as evidenced by the sharp increase in recent years in the number of scientific publications on topics related to the image or its aspects. As a result of research using the methods of a questionnaire survey followed by in-depth interviews in focus groups, the ranking structure of the expert model of an ideal modern leader and the ranking structure of the image model of a modern leader in everyday consciousness are presented. The findings of the study described the socio-psychological mechanisms of the functioning of the image as a phenomenon of interpersonal interaction, including: the manifestation of the characteristics of group interaction; the use of social representations and stereotypes; the realization of the self-concept of the subject of the image in correlation relationships with the self-concepts of other subjects of image interaction and the like. The disclosure of the socio-psychological mechanisms of the functioning of the image, their accounting and use are necessary for the development of productive activities on the formation of an optimal image as a phenomenon of interpersonal interaction.

Исследование волевой сферы личности курсантов, обучающихся в образовательных организациях МВД России открытого и закрытого типов

The article presents the results of the study of the volitional sphere of employees of the internal Affairs bodies. With the help of comparative analysis the distinctive psychological features of volitional regulation of cadets and students studying in educational institutions of the Ministry of internal Affairs of Russia of open and closed types are revealed. The authors for the first time presented the characteristics of two types of educational institutions of the Ministry of internal Affairs of Russia (open and closed), influencing the features of the development of the volitional sphere of students. Based on the results of the study, it is concluded that when comparing the data of self-assessments of volitional qualities, the identity of the rank structure of volitional qualities in the tested educational organizations of open and closed types is found. When comparing the results obtained by using the method of the scale of control over the action of Kulya, it is revealed that orientation to the state (self — control) during realization of intention in action is stronger developed at cadets (listeners) of the educational organization of open type of training, and orientation to action (self-regulation) - at subjects of the educational organization of the closed type of training.

Spectral Compressed Sensing via Projected Gradient Descent

Let $x\in\mathbb{C}^n$ be a spectrally sparse signal consisting of $r$ complex sinusoids with or without damping. We consider the spectral compressed sensing problem, which is about reconstructing $x$ from its partial revealed entries. By utilizing the low rank structure of the Hankel matrix corresponding to $x$, we develop a computationally efficient algorithm for this problem. The algorithm starts from an initial guess computed via one-step hard thresholding followed by projection, and then proceeds by applying projected gradient descent iterations to a non-convex functional. Based on the sampling with replacement model, we prove that $O(r^2\log(n))$ observed entries are sufficient for our algorithm to achieve the successful recovery of a spectrally sparse signal. Moreover, extensive empirical performance comparisons show that our algorithm is competitive with other state-of-the-art spectral compressed sensing algorithms in terms of phase transitions and overall computational time.

A Novel Framework for Wireless Digital Communication Signals via a Tensor Perspective

In this paper, we introduce a novel signal characteristic, which is ubiquitous in the vast majority of communication signals. That is, a modulated signal is of an inherent low-rank structure following a reshaping operation. We first use a toy model to develop a framework for modelling this signal characteristic, and theoretically prove the impact on the signals’ rank structure by additive white Gaussian noise and inter-symbol interference, which is of great concern in the wireless communication field. Subsequently, the model is generalized to multi-input-multi-output signals, and tensor rank is taken into account. Using multi-linear algebra, we prove that the low-rankness of a reshaped signal only depends on the structure of its embedding subspace, and that its rank measure is upper bounded by the multi-rank of the basis tensor. As an application, we propose a novel adaptive sampling and reconstruction scheme for generic software-defined radio based on the low-rank structure. Numerical simulations demonstrate that the proposed method outperforms compressed sensing-based method, particularly when the modulated signal does not satisfy the sparsity assumption in the time and frequency domains. The results of practical experiments further demonstrate that many types of modulated signals can be effectively reconstructed from very limited observations using our proposed method.

Bioactive focus in conformational ensembles: a pluralistic approach.

Computational generation of conformational ensembles is key to contemporary drug design. Selecting the members of the ensemble that will approximate the conformation most likely to bind to a desired target (the bioactive conformation) is difficult, given that the potential energy usually used to generate and rank the ensemble is a notoriously poor discriminator between bioactive and non-bioactive conformations. In this study an approach to generating a focused ensemble is proposed in which each conformation is assigned multiple rankings based not just on potential energy but also on solvation energy, hydrophobic or hydrophilic interaction energy, radius of gyration, and on a statistical potential derived from Cambridge Structural Database data. The best ranked structures derived from each system are then assembled into a new ensemble that is shown to be better focused on bioactive conformations. This pluralistic approach is tested on ensembles generated by the Molecular Operating Environment's Low Mode Molecular Dynamics module, and by the Cambridge Crystallographic Data Centre's conformation generator software.

Atp1a3-deficient heterozygous mice show lower rank in the hierarchy and altered social behavior.

Atp1a3 is the Na-pump alpha3 subunit gene expressed mainly in neurons of the brain. Atp1a3-deficient heterozygous mice (Atp1a3+/- ) show altered neurotransmission and deficits of motor function after stress loading. To understand the function of Atp1a3 in a social hierarchy, we evaluated social behaviors (social interaction, aggression, social approach and social dominance) of Atp1a3+/- and compared the rank and hierarchy structure between Atp1a3+/- and wild-type mice within a housing cage using the round-robin tube test and barbering observations. Formation of a hierarchy decreases social conflict and promote social stability within the group. The hierarchical rank is a reflection of social dominance within a cage, which is heritable and can be regulated by specific genes in mice. Here we report: (1) The degree of social interaction but not aggression was lower in Atp1a3+/- than wild-type mice, and Atp1a3+/- approached Atp1a3+/- mice more frequently than wild type. (2) The frequency of barbering was lower in the Atp1a3+/- group than in the wild-type group, while no difference was observed in the mixed-genotype housing condition. (3) Hierarchy formation was not different between Atp1a3+/- and wild type. (4) Atp1a3+/- showed a lower rank in the mixed-genotype housing condition than that in the wild type, indicating that Atp1a3 regulates social dominance. In sum, Atp1a3+/- showed unique social behavior characteristics of lower social interaction and preference to approach the same genotype mice and a lower ranking in the hierarchy.