In this paper, we extend the generalized approximate message passing (G-AMP) approach, originally proposed for high-dimensional generalized-linear regression in the context of compressive sensing, to ...the generalized-bilinear case, which enables its application to matrix completion, robust PCA, dictionary learning, and related matrix-factorization problems. Here, in Part I of a two-part paper, we derive our Bilinear G-AMP (BiG-AMP) algorithm as an approximation of the sum-product belief propagation algorithm in the high-dimensional limit, where central-limit theorem arguments and Taylor-series approximations apply, and under the assumption of statistically independent matrix entries with known priors. In addition, we propose an adaptive damping mechanism that aids convergence under finite problem sizes, an expectation-maximization (EM)-based method to automatically tune the parameters of the assumed priors, and two rank-selection strategies. In Part II of the paper, we will discuss the specializations of EM-BiG-AMP to the problems of matrix completion, robust PCA, and dictionary learning, and we will present the results of an extensive empirical study comparing EM-BiG-AMP to state-of-the-art algorithms on each problem.
Across the brain sciences, institutions and individuals have begun to actively acknowledge and address the presence of racism, bias, and associated barriers to inclusivity within our community. ...However, even with these recent calls to action, limited attention has been directed to inequities in the research methods and analytic approaches we use. The very process of science, including how we recruit, the methodologies we utilize and the analyses we conduct, can have marked downstream effects on the equity and generalizability of scientific discoveries across the global population. Despite our best intentions, the use of field-standard approaches can inadvertently exclude participants from engaging in research and yield biased brain-behavior relationships. To address these pressing issues, we discuss actionable ways and important questions to move the fields of neuroscience and psychology forward in designing better studies to address the history of exclusionary practices in human brain mapping.
Vinylsilanes and vinylboronates are common building blocks for organic synthesis, but direct functionalization of these species without the participation of either the C=C or C−Si/B bonds is rare. ...Herein, we report a metal‐free allylic C−H amination reaction of these vinylmetalloid species that installs a new C−N bond without competing transmetallation or alkene addition. In this transformation, the silicon or boron substituent inverts the usual regioselectivity, directing amination to the site distal to that group. Subsequent cross‐coupling or demetallation allows access to complementary regioisomeric products. Density Functional Theory computations revealed that the observed regioselectivity is due to a subtle combination of electronic and counterintuitive steric factors that favor initial attack of selenium at the silicon‐bearing carbon atom.
A metal‐free allylic C−H amination protocol allows simple vinylsilanes and vinylboronates to be selectively functionalized without competitive consumption of the reactive vinylmetalloid core structure, preserving its reactivity for future transformations such as cross‐coupling or addition reactions. The silicon/boron group directs the regioselectivity of amination to the distal side of the C=C bond, allowing access to a complementary substitution pattern.
Remote sensing with radar is typically an ill-posed linear inverse problem: a scene is to be inferred from limited measurements of scattered electric fields. Parsimonious models provide a compressed ...representation of the unknown scene and offer a means for regularizing the inversion task. The emerging field of compressed sensing combines nonlinear reconstruction algorithms and pseudorandom linear measurements to provide reconstruction guarantees for sparse solutions to linear inverse problems. This paper surveys the use of sparse reconstruction algorithms and randomized measurement strategies in radar processing. Although the two themes have a long history in radar literature, the accessible framework provided by compressed sensing illuminates the impact of joining these themes. Potential future directions are conjectured both for extension of theory motivated by practice and for modification of practice based on theoretical insights.
In this paper, we extend the generalized approximate message passing (G-AMP) approach, originally proposed for high-dimensional generalized-linear regression in the context of compressive sensing, to ...the generalized-bilinear case. In Part I of this two-part paper, we derived our Bilinear G-AMP (BiG-AMP) algorithm as an approximation of the sum-product belief propagation algorithm in the high-dimensional limit, and proposed an adaptive damping mechanism that aids convergence under finite problem sizes, an expectation-maximization (EM)-based method to automatically tune the parameters of the assumed priors, and two rank-selection strategies. Here, in Part II, we discuss the specializations of BiG-AMP to the problems of matrix completion, robust PCA, and dictionary learning, and present the results of an extensive empirical study comparing BiG-AMP to state-of-the-art algorithms on each problem. Our numerical results, using both synthetic and real-world datasets, demonstrate that EM-BiG-AMP yields excellent reconstruction accuracy (often best in class) while maintaining competitive runtimes.
Scholars have advocated for further investigation of the campus climate for diversity and students’ attitudes and behaviors surrounding diversity, and there appears to be an increasing responsibility ...for higher education professionals to consider ways to encourage students’ awareness and acceptance of difference. Using longitudinal data from the Wabash National Study of Liberal Arts Education, this study examined the relationship between students’ perceptions of faculty practices and student-faculty interactions and two measures of students’ attitudes toward diversity, and whether these relationships were moderated by race/ethnicity. Findings revealed that several perceptions of faculty practices and student-faculty interactions were positively associated with students’ fourth-year diversity attitudes, including: (a) quality of faculty contact; (b) faculty interest in teaching and student development; (c) how often students had discussions with faculty whose political, social, or religious opinions were different from their own; (d) how often faculty engaged students in cooperative learning activities; (e) whether courses helped students see connections between intended careers and how they affect society; and (f) whether courses helped students understand the historical, political, and social connections of past events. Overall, findings suggest that the type and quality of each faculty practice or measure of interaction with students may be significant in terms of fostering positive diversity attitudes among students. Implications for policy and practice are discussed.
An orthogonal combination of cationic and radical RAFT polymerizations is used to synthesize bottlebrush polymers using two distinct RAFT agents. Selective consumption of the first RAFT agent is used ...to control the cationic RAFT polymerization of a vinyl ether monomer bearing a secondary dormant RAFT agent, which subsequently allows side‐chain polymers to be grafted from the pendant RAFT agent by a radical‐mediated RAFT polymerization of a different monomer, thus completing the synthesis of bottlebrush polymers. The high efficiency and selectivity of the cationic and radical RAFT polymerizations allow both polymerizations to be conducted in one‐pot tandem without intermediate purification.
Selective chain transfer between two RAFT agents enabled orthogonal cationic and radical RAFT polymerizations to synthesize bottlebrush polymers. The high efficiency and selectivity of the polymerizations allow both to be conducted in one‐pot tandem without intermediate purification.
Females of container-breeding mosquito species use visual and chemical cues to determine suitable habitats to oviposit their eggs. Female Culex mosquitoes oviposit single egg rafts containing ...hundreds of eggs on the surface of water in container habitats. In this project, the effects of water volume and nutrient concentration were studied using three semi-controlled field assays to determine the role these parameters play on female Culex mosquito oviposition preference. The results of this study suggest female Culex prefer to oviposit in larger volumes of water and higher concentrations of nutrients separately, but chose intermediate conditions when presented with a combination of these two variables, which follows the Goldilocks principle. This choice may provide their offspring with optimal conditions for development by reducing intraspecific competition, thereby maximizing the biological fitness of the ovipositing Culex females.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) spacecraft landed successfully on Mars and imaged the surface to characterize the surficial geology. Here ...we report on the geology and subsurface structure of the landing site to aid in situ geophysical investigations. InSight landed in a degraded impact crater in Elysium Planitia on a smooth sandy, granule- and pebble-rich surface with few rocks. Superposed impact craters are common and eolian bedforms are sparse. During landing, pulsed retrorockets modified the surface to reveal a near surface stratigraphy of surficial dust, over thin unconsolidated sand, underlain by a variable thickness duricrust, with poorly sorted, unconsolidated sand with rocks beneath. Impact, eolian, and mass wasting processes have dominantly modified the surface. Surface observations are consistent with expectations made from remote sensing data prior to landing indicating a surface composed of an impact-fragmented regolith overlying basaltic lava flows.
PDF
