Source Constellations Research Articles

Deep ocean long range underwater navigation with ocean circulation model corrections.

An underwater navigation algorithm that provides a "cold start" (CSA) geographic position, geo-position, underwater while submerged using travel times measured from a constellation of acoustic sources is described in Mikhalevsky, Sperry, Woolfe, Dzieciuch, and Worcester [J. Acoust. Soc. Am. 147(4), 2365 - 2382 (2020)]. The CSA geo-position is used as the receive position in the ocean for acoustic modeling runs using an ocean general circulation model (GCM). A different geo-position is calculated using adjusted ranges from the travel time offsets between the data and modeled arrival times for each source. Because the CSA geo-position is close to the true position, the source to CSA position propagation model path and the source to true vehicle position data path of the acoustic arrivals are nearly coincident, enabling accurate measurement of travel time offsets. The cold start with model (CSAM) processing reduced the CSA geo-position errors from a mean of 58 to 25 m. A simulation is developed to estimate CSA and CSAM performances as a function of group speed variability between the source paths. The CSAM geolocation accuracy can be calculated from and is controlled by the accuracy of the GCM.

VLA Measurements of Faraday Rotation Through a Coronal Mass Ejection Using Multiple Lines of Sight

Coronal mass ejections (CMEs) are large eruptions of magnetized plasma from the Sun that play an important role in space weather. The key to understanding the fundamental physics of a CME is measurement of the plasma properties within heliocentric distances of $< 20~\mathrm{R}_{\odot }$ . Faraday rotation, a radioastronomical propagation measurement, is an extremely valuable diagnostic for studying CMEs. Faraday rotation measurements [RM] contain information on the magnetic field in the medium causing the Faraday rotation. Recent observations of CME-induced Faraday rotation (e.g., Howard et al. in Astrophys. J. 831, 208, 2016; Kooi et al. in Solar Phys. 292, 56, 2017; Bisi et al. in EGU General Assembly Conference Abstracts, 13243, 2017) have all been restricted to a single line of sight (LOS) and, therefore, limited to providing estimates of the magnetic field strength. Modeling by Liu et al. (Astrophys. J. 665, 1439, 2007) and Jensen and Russell (Geophys. Res. Lett. 35, L02103, 2008) demonstrated that multiple LOS are necessary to recover the magnetic field strength and structure of the observed CME. We report the first successful observations of Faraday rotation through a CME using multiple lines of sight: 13 LOS across seven target radio fields. We made these radio observations using the Karl G. Jansky Very Large Array (VLA) at $1-2$ GHz frequencies in the triggered operation mode on 31 July 2015, using a constellation of cosmic radio sources through the solar corona at heliocentric distances of $8.2-19.5~\mathrm{R}_{\odot }$ . For LOS within $10~\mathrm{R}_{\odot }$ , the CME’s contribution to the measured RM was $\approx 0$ to −20 rad m−2, a significant enhancement over the coronal contribution. We assumed a force-free flux-rope structure for the CME’s magnetic field and explored three separate models for the CME’s plasma density: constant density, thin shell, and thick shell. The plasma densities and axial magnetic field strengths for the three models ranged over $5.4-6.4\times 10^{3}$ cm−3 and $26-35$ mG, respectively. Further, using all 13 LOS, we successfully determined the CME’s orientation and helicity.

Physical Literacy and Resilience in Children and Youth.

Background: There is growing interest in the relationship between physical and psychosocial factors related to resilience to better understand the antecedents of health and successful adaptation to challenges in and out of school, and across the lifespan. To further this understanding, a trans-disciplinary approach was used to investigate the association between the multidimensional constructs of physical literacy and resilience in children at a key stage in their development.Methods: Cross-sectional data were collected from 227 school children aged 9-12 years old from five schools in Winnipeg, Manitoba, Canada. Resilience was measured using the Child and Youth Resilience Measure, and physical literacy through the Physical Literacy Assessment for Youth tools. Data were provided by self-report, surrogate assessors of the child (physical education teachers and parents), and trained assessors for movement skills. These data were analyzed using correlation and logistic regression.Results: Resilience was significantly correlated with numerous indicators of physical literacy, including movement capacity, confidence, and competence, environmental engagement, and overall perceptions of physical literacy. Regressions indicated that resilience could be predicted by movement confidence and competence, environmental engagement, and overall physical literacy.Conclusions: The findings of this study, using a constellation of sources, provide foundational evidence for the link between resilience and physical literacy among children, encouraging the importance of physical literacy development in schools. Longitudinal studies are required to further examine this relationship and how these previously unrelated fields may work together for a richer understanding of the interplay between the physical and psychological determinants of well-being.

Joseph Johnson's Lost Gamuts: Native Hymnody, Materials of Exchange, and the Colonialist Archive

AbstractIn the winter of 1772–1773, Joseph Johnson (Mohegan/Brothertown) copied musical notation into eight books for Christian Native Americans in Farmington, Connecticut, a town established by English settler colonists on the land known as Tunxis Sepus. Johnson did so because, as he wrote in his diary, “The indians are all desireous of haveing Gamuts.” Johnson's “gamuts” have not survived, but their erstwhile existence reveals hymnody's important role within the Native community in Farmington as well as cross-culturally with the English settler colonists. In order to reconstruct the missing music books and assess their sociocultural significance, this article proposes a surrogate bibliography, gathering a constellation of sources among which Johnson's books would have circulated and gained meaning for Native American Christians and English colonists (including other printed and manuscript music, wampum, and legal documents pertaining to land transfer). By bringing together this multi-modal network of materials, this essay seeks to redress the material and epistemological effects of a colonialist archive. On one level, this is a case study that focuses on a short period of time in order to document the impact on sacred music of conversion, literacy, shifting intercultural relations, and a drive to preserve sovereignty. On another, this article presents a methodological intervention for dealing with lost materials and colonialist archives without recourse to discourses of recovery or discovery, the latter of which is considered through the framework of what I term “archival orientalism.”

A Moment-Based Estimation Strategy for Underdetermined Single-Sensor Blind Source Separation

We investigate the blind identification and separation of underdetermined linear instantaneous mixtures with a single sensor and an arbitrary known number of sources with finite known support and uniform distribution. We propose channel estimators based on the high-order statistics of the received signal and on the rotational symmetries of the source constellations. Explicit expressions for distinct and equal rotation orders are derived. The proposed estimators are used as initializers for the iterative least squares with enumeration algorithm to enhance its convergence properties. Simulation results on several high interference two-user wireless communication scenarios show that our initialization strategy achieves a substantial performance gain compared to other traditional initializers.

Experiencing violence in a cross-media environment: an interdisciplinary focus group study

ABSTRACTDue to drastic changes in the contemporary media environment, criminology needs to examine how the experience of violence is shaped by the emerging cross-media context. We conducted a qualitative focus group study (N = 24) to explore conversations about mediated violence experiences and crime media literacy in Finland, which manifests as an advanced state of cross-media transformation. We found that the cross-media context affects how information on violence and crime is received, as people combine and contrast bits of information from traditional media, social media, alternative media, and direct personal and local knowledge. This constellation of information sources is a fertile ground for distrust, as people challenge the self-regulatory limits of ‘old media’ in reporting on crime and construe such limits as ‘downplaying’ violence. Consistent with the general ‘media-critical’ frame of mind, the interviewees saw crime news media as fear-inducing. Through a focus group of older participants (in addition to three groups of younger participants), we observed generational differences that reflect the dimension of change from the old monolithic media environment to the cross-media context. The new context blurs the distinction between media content and social network-based reception and is thus a game changer for media criminology.

Navigating fluid epistemic spaces: emerging challenges for student knowing and learning in public international law

ABSTRACTThis article explores challenges for knowing and learning in evolving knowledge fields. Legal education is chosen as a particularly interesting case as the knowledge field of law is expanding to international law with a multitude of actors, obligations, conventions and interpreters. In the current study, students’ group work with case assignments was observed and interviews with students and teachers conducted within a course in public international law. The following question was examined: What learning challenges do the students face when solving cases in international law? By employing sociomaterial perspectives on navigation as finding ways to interpretational possibilities in evolving and complex constellations of procedures, texts, and various actors in the knowledge field, the study pursued an analytical interest in how professional resources were assembled in the students’ work, and how such assemblages served to order practice and justify their decisions. The analysis showed that the students’ previously learned strategies for linking authoritative texts and questions in defining and solving legal problems were challenged by less stabilised constellations of textual sources and interpreters of law. The analysis also revealed tensions in the course setting between demands of navigating more open knowledge landscapes and expectations about student behaviour in current educational practices.

Capability-based localization of distributed and heterogeneous queries

AbstractOne key aspect of data-centric applications is the manipulation of data stored in persistent repositories, which is moving fast from querying a centralized relational database to the ad-hoc combination of constellations of data sources. The extension of general purpose languages with query operations is increasingly popular, as a tool to improve reasoning and optimizing capabilities of interpreters and compilers. However, not much is being done to integrate and orchestrate different and separate sources of data. We present a data manipulation language that abstracts the nature and location of data-sources. We define its semantics and a type directed query localization mechanism to be used in development tools for heterogeneous environments to efficiently compile them into native queries. We introduce a localization procedure based on rewriting of query expressions that is confluent, terminating and provides the maximum mapping between site capabilities and the structure of the query. We provide formal type safety results that support the sound distribution of query fragments over remote sites. Our approach is also suitable for an interactive query construction environment by rich user interfaces that provide immediate feedback on data manipulation operations. This approach is currently the base for the data layer of a development platform for mobile and web applications.

A new method for measuring historical poverty trends: Incorporating geographic differences in the cost of living using the Supplemental Poverty Measure

The U.S. Census Bureau and the Bureau of Labor Statistics recently developed a substantially improved measure of poverty, the Supplemental Poverty Measure (SPM). The SPM has only been released since 2009, and prior efforts by researchers to construct a historical SPM time series have not taken into account an essential element of the new measure - geographical differences in the cost of living - which is necessary for accurately describing poverty trends in important demographic and regional subgroups. We build the first historical SPM time series from 1967-2014 that adjusts poverty thresholds for cost of living. We do so bringing together a constellation of data sources - the Current Population Survey, the Decennial Census, the Department of Housing and Urban Development's Fair Market Rents, and others. We find that geographically adjusting thresholds increases poverty rates in metro areas, the Western states, and among Latinos, but decreases poverty rates in non-metro areas and in the South. The geographic adjustment of poverty thresholds is an impactful component of the SPM.

Limited-Feedback Massive MISO Systems With Trellis-Coded Quantization for Correlated Channels

In this paper, we propose trellis coded quantization (TCQ) based limited feedback techniques for massive multiple-input single-output (MISO) frequency division duplexing (FDD) systems in temporally and spatially correlated channels. We exploit the correlation present in the channel to effectively quantize channel direction information (CDI). For multiuser (MU) systems with matched-filter (MF) precoding, we show that the number of feedback bits required by the random vector quantization (RVQ) codebook to match even a small fraction of the perfect CDI signal-to-interference-plus-noise ratio (SINR) performance is large. With such large numbers of bits, the exhaustive search required by conventional codebook approaches make them infeasible for massive MISO systems. Motivated by this, we propose a differential TCQ scheme for temporally correlated channels that transforms the source constellation at each stage in a trellis using 2D translation and scaling techniques. We derive a scaling parameter for the source constellation as a function of the temporal correlation and the number of BS antennas. We also propose a TCQ based limited feedback scheme for spatially correlated channels where the channel is quantized directly without performing decorrelation at the receiver. Simulation results show that the proposed TCQ schemes outperform the existing noncoherent TCQ (NTCQ) schemes, by improving the spectral efficiency and beamforming gain of the system. The proposed differential TCQ also reduces the feedback overhead of the system compared to the differential NTCQ method.

International Relations as a Social Science

In this written version of his inaugural lecture for the Montague Burton chair in IR at the LSE, Iver Neumann takes stock of International Relations understood as a social science. Having paid homage to predecessors, in the first part of the lecture, he detects and regrets a certain unwillingness within the discipline to address the full universe of pertinent cases. Inspecting the toolbox of the discipline, he finds things to be satisfactory where data collection, theory and meta-theory are concerned, but traces a glaring lack of attention to data collection method among qualitative (as opposed to quantitative) scholars. In the lecture’s second part, Neumann draws on Marcel Mauss’s idea that human agency draws on a constellation of social, psychological and physiological sources and on Emile Durkheim’s insistence that a social science has to privilege social sources of agency, without neglecting sources of other kinds. A nutshell review of relevant trends within psychology and evolutionary biology highlights work that competes with the discipline’s own. While insisting, with Durkheim, on the need to privilege social causes, Neumann calls for more work that explores the possible compatibility of new findings within these non-social disciplines and International Relations.

MEMS Kinematics by Super-Resolution Fluorescence Microscopy

Super-resolution fluorescence microscopy is used for the first time to study the nanoscale kinematics of a MEMS device in motion across a surface. A device under test is labeled with fluorescent nanoparticles that form a microscale constellation of near-ideal point sources of light. The constellation is imaged by widefield epifluorescence microscopy, and the image of each nanoparticle is fit to a Gaussian distribution to calculate its position. Translations and rotations of the device are measured by computing the rigid transform that best maps the constellation from one image to the next. This technique is used to measure the stepwise motion of a scratch drive actuator across each of 500 duty cycles with 0.13-nm localization precision, 1.85-nm displacement uncertainty, and 100-μrad orientation uncertainty for a constellation diameter of 15 μm. This novel measurement reveals acute aperiodic variations in the step size of the actuator, which have been neither previously observed nor predicted by any of the published models of the operation of the device. These unexpected results highlight the importance of super-resolution fluorescence microscopy to the measurement of MEMS kinematics, which will have broad impact in fundamental investigations of surface forces, wear, and tribology in MEMS and related applications.

Effect of Channel Noise on Blind Equalization and Carrier Phase Recovery of CMA and MMA

This work investigates the effect of channel noise on the performances of the constant modulus algorithm (CMA), the multimodulus algorithm (MMA), and a phase tracker (PT), following the CMA for carrier phase recovery, when various symmetrical two-dimensional complex-valued source constellations are used. The contributions of this work are two-fold. First, a generalized formulation of the relocation of stationary points toward the origin owing to channel noise is derived for both the CMA and the MMA, allowing their sensitivity to channel noise to be explicitly compared when various constellations are used. Second, the curvatures of the error surface at the stationary points in both the radial and the angular directions are reduced in a way that is linearly proportional to the square of the distances between the stationary points and the origin as the stationary points of the CMA and the MMA relocate toward the origin in the presence of additive channel noise. The reduction of the error surface curvature in the radial direction reduces the rate of blind equalization convergence, whereas the reduction in the angular direction degrades the capacity for carrier phase recovery.

Non-Uniform 2-Slot Constellations for Relaying in Butterfly Network with Imperfect Side Information

There are two key aspects affecting the performance of butterfly network with wireless network-coded relaying. The first one is the amount of Complementary Side Information (C-SI) at destinations and the second is given by a parametric Multiple-Access channel performance of source constellation alphabets. In this paper we show that theNon-uniform 2-slot (NuT) constellations, proposed originally for bi-directional relaying in the 2-Way Relay Channel (2-WRC), are suitable also for the butterfly network, combining the favorable parametric channel performance with the potential to increase the reliability of required C-SI (necessary for successful decoding at the final destination). Possessing both these qualities, the NuT alphabets surpass again the conventional linear modulation schemes, extending further the scope of their potential application.

Optimised Constellation Prerotation for 3-Terminal 1-Relay Network with Wireless Network Coding

Wireless (Physical-Layer) Network Coding (WNC) is an interference harnessing physical-layer concept combining network coding principles and broadcast nature of the wireless medium. Significant capacity gains of WNC were shown in a wireless 2-Way Relay Channel (2-WRC). Extension of WNC to more complicated network topologies potentially offers even larger gains than in the 2-WRC. However, such an extension is generally non-trivial. In this paper, we show that it is feasible to achieve additional considerable capacity gains in comparison to bidirectional relaying approach in a three-terminal one-relay network. We focus on the constellation design for its uplink (Multiple Access Channel (MAC) stage). The throughput maximisation is achieved by an optimised prerotation of source constellations, effectively reducing a number of required MAC stages.

A Cartesian non‐uniform grid interpolation method for fast field evaluation on elongated domains

SUMMARYAn algorithm for performing a fast evaluation on time harmonic fields radiated by two‐dimensional source constellations with elongated geometry is introduced. The suggested scheme attains a linear computational complexity. At the core of the algorithm is the idea of phase and amplitude compensation facilitating the conversion of fields radiated by spatially confined sources into bandlimited functions of the suitable coordinates. Thus, the fields or potentials are represented by their samples on sparse left‐side and right‐side non‐uniform Cartesian grids. These grids are employed both for the representation of outgoing fields and as targets for accumulating the incoming fields. Integrating this approach with the divide‐and‐conquer strategy, the algorithm relies on a binary hierarchical decomposition of the computational domain. The total field is computed via a two‐way multilevel process, which passes through all of the left‐side and right‐side grids, while systematically aggregating all subdomains' contributions, ending with the field interpolation back to the desired observation points. Copyright © 2012 John Wiley &amp; Sons, Ltd.

The link between soundscape perception and attention processes

In order to understand the perception and evaluation of soundscapes, it appears mandatory to concentrate not only on constellations of sources and their contributions to the acoustic environment, but also to consider attention processes towards sound sources. It is widely known that a listener can easily focus on a certain source and can suppress the noise of other sources, which is called cocktail-party effect. It is assumed that this effect greatly influences the general appreciation of the whole soundscape. However, the process, why people focus on certain sound sources and how this influences the overall evaluation, has to be explored. A detailed knowledge about the (often subconscious) focussing on sources in multi-source soundscapes would be very helpful for design purposes, to attract deliberately attention to certain sound sources leading to positive feelings for the majority of soundscape visitors. Laboratory results dealing with the effect of source attention and its impact on soundscape evaluation were already published. In these surveys it was found that the processes, in which way the global impression changes due to the attention attraction to certain sources, seem to be complex. The paper will focus now on in-situ assessments and will show new results gained in field experiments.

Impacts on soundscape appreciation by focussing on sources

Based on COST, the European Cooperation in Science and Technology as an instrument supporting cooperation among scientists and researchers across Europe, collaborations among soundscape researchers was and is still encouraged (COST action TD 0804). In this context, researchers from 18 COST countries and 7 partners outside Europe come together and work on terminology, collection and documentation of soundscapes, harmonization of methodologies and indicators, and design of soundscapes. One scientific issue deals with sound source constellations in soundscapes and evoked attention-attracting processes. Humans can easily focus on a certain source suppressing the noise of other sources. This process obviously influences the general appreciation of the whole soundscape. In different tests this phenomenon was investigated and its potential analyzed with respect to soundscape design. The process of international and interdisciplinary cooperation within the COST framework will be shortly described and benefits and limitations discussed. Moreover, different case studies will be presented to show the effect of source attention and its impact on soundscape evaluation.

Governo da ley ou governo dos juizes? O primeiro século do Supremo Tribunal de Justiça em Portugal

The installment of High Courts of Justice by the constitutional regimes of the early 19 th century was related, rather than to the provision of a third instance of appeal, to a structural principles of a new political order - the separation and independence of powers, ensuring that neither the executive nor the judicial could encroach the primacy of parliamentary law. let the courts enforce the law. This was the origin of the institute of Cassation . Behind this question of political doctrine, a less doctrinal political issue was at stake, namely the tension between lawyers and politicians in the conformation of law in a democratic State. The Portuguese Supremo Tribunal de Justica (1822) arose in this context. Its aim was both to syndicate magistrates charged with misbehavior and, above all, to ensure compliance of administration and justice with the law. With the whole law, not with parliamentary statute law. With the law – it is meant -, understood with the span coming from the Ancient Regime, a doctrinal and jurisprudential law, based on the diverse constellation of sources of law provided in the Lei da Boa Razao (1769) and in the enlightened University reform of Legal Studies, 1772. Accordingly, far from being a guarantor of the new constitution and of new legality, the new high court could function as a factor of corruption of the new constitutional and legal order, as both the Constitution and laws could be subject to the filter of traditional law. In this way, a State based on popular would turn into a State geared by the body of legal professionals, a situation eagerly coveted by lawyers. Submission Date: 17/03/2011 Acceptance Date: 4/05/2011

Soundscape analysis: Need for (automatic) source separation.

The use of psychoacoustics for soundscape analysis is imperative to predict the soundscape from an acoustical point of view. Psychoacoustic parameters as functions of intensity, time structure, and spectral content play an important role with respect to several sensations and yield information with greater differentiation than usually applied indicators within the community noise context. But, with respect to a comprehensive analysis of a soundscape, the exact source constellation must be known. Based on the performance of the human hearing system including intelligent signal processing, a listener can easily focus on a certain source and suppress the noise of other sources, which considerably influences the general appreciation of the whole soundscape. For example, this ability is permanently used to improve speech intelligibility in noisy environments. Therefore, an acoustical soundscape analysis should not just deal with the overall noise, but rather the (psycho-)acoustical properties of the different sources present in a soundscape must be investigated separately. Different methods are conceivable in realizing source separation in complex noise scenarios. The paper will present a few case studies demonstrating the opportunities in separating the contributions of several sound sources within a soundscape.