scholarly journals Weight Sensitivity of Temporal SNR Metrics in multi-echo fMRI

2020 ◽  
Author(s):  
Thomas T. Liu ◽  
Bochao Li ◽  
Conan Chen ◽  
Brice Fernandez ◽  
Baolian Yang ◽  
...  
Keyword(s):  
Covariance Matrix ◽  
Resting State Fmri ◽  
Rayleigh Quotient ◽  
Weighting Schemes ◽  
High Matrix ◽  
Optimal Values ◽  
Matrix Similarity ◽  
High Degree ◽  
Generalized Rayleigh Quotient ◽  
Insight Into

AbstractPurposeIn multi-echo fMRI (ME-fMRI), various weighting schemes have been proposed for the combination of the data across echoes. Here we introduce a framework that facilitates a deeper understanding of the weight dependence of temporal SNR measures in ME-fMRI.Theory and MethodsWe examine two metrics that have been used to characterize ME-fMRI performance: temporal SNR (tSNR) and multi-echo temporal (metSNR). Both metrics can be described using the generalized Rayleigh quotient (GRQ) and are predicted to be relatively insensitive to the weights when there is a high degree of similarity between a metric-specific matrix in the GRQ numerator and a metricindependent covariance matrix in the GRQ denominator. The application of the GRQ framework to experimental data is demonstrated using a resting-state fMRI dataset acquired with a multi-echo multi-band EPI sequence.ResultsIn the example dataset, similarities between the covariance matrix and the metSNR and tSNR numerator matrices are highest in grey matter (GM) and cerebrospinal fluid (CSF) voxels, respectively. For representative GM and CSF voxels that exhibit high matrix similarity values, the metSNR and tSNR values, respectively, are both within 4% of their optimal values across a range of weighting schemes. However, there is a fundamental tradeoff, with a high degree of weight sensitivity in the tSNR and metSNR metrics for the representative GM and CSF voxels, respectively. Geometric insight into the observed weight dependencies is provided through a graphical interpretation of the GRQ.ConclusionA GRQ framework can provide insight into the factors that determine the weight sensitivity of tSNR and metSNR measures in ME-fMRI.

Oil Companies and Climate Change: Inconsistencies between Strategy Formulation and Implementation?

2007 ◽  
Vol 7 (3) ◽  
pp. 42-62 ◽  
Author(s):  
Ingvild Andreassen Sæverud ◽  
Jon Birger Skjærseth
Keyword(s):  
Climate Change ◽  
Strategy Formulation ◽  
Oil Companies ◽  
Corporate Strategies ◽  
International Climate ◽  
Framework Conditions ◽  
High Degree ◽  
The Relationship ◽  
Level 2 ◽  
Insight Into

This article examines major oil companies in terms of climate strategies and their implementation. More specifıcally, it takes a critical look at Shell, BP, and ExxonMobil, and the relationship between rhetoric and action regarding investments in climate-friendly activities. Empirical evidence indicates a generally high degree of consistency between what these companies say and what they do, but interesting differences are also found: ExxonMobil has done somewhat more than its climate strategy formulations would suggest; Shell has done somewhat less; whereas BP's activities are mainly in line with its statements. Factors at three levels contribute to explaining these differences: (1) the company level, 2) the political framework conditions in the various regions where the companies operate, 3) international climate cooperation. The fındings and explanations, although restricted to the three oil companies with regard to climate change, provide insight into the relationship between corporate strategies and implementation more generally. They offer understanding and analytical categories for assessing how well and why such multinational entities put into practice stated objectives.

scholarly journals Vies en Vlaams: de literaire contestatie uit de jaren zestig

1970 ◽  
Vol 64 ◽  
pp. 117-128
Author(s):  
Liesbeth Plateau
Keyword(s):  
Literary History ◽  
Systematic Investigation ◽  
Nineteen Sixties ◽  
Literary Field ◽  
Short Life ◽  
Short Life Span ◽  
Cultural Life ◽  
Key Players ◽  
High Degree ◽  
Insight Into

This contribution presents an introductory analysis of one of the key players of the socalled“stenciled revolution” in Flanders in the nineteen sixties. Before concepts likeprovo distressed the entire societal and cultural life in the Netherlands, certain phenomenain Flanders anticipated to this. From 1963, small stenciled magazines shot up likemushrooms in the Flemish literary field. Due to their aggressive stand against the literaryestablishment, the critics quickly caught sight of them and engaged in an energeticpolemic. Because of their involvement in the literary polemics, the stenciled magazinesshortly determined the literary life to a high degree. However, partly due to their complexhistory and short life span, a systematic investigation of this phenomenon has not yet beenconducted. Nevertheless, the underground- magazines of the “stenciled revolution” are invarious ways relevant to a renewed literary history, as they explore both the literary-criticaland the creative-literary boundaries of the traditional contrast between literature andnon-literature. In this article, I focus on one of the most creative-literary oriented of theseFlemish stenciled magazines, namely daele (1966-1968), to gain an insight into the identityof the “stenciled revolution”.

scholarly journals Complex Minisatellite Rearrangements Generated in the Total or Partial Absence of Rad27/hFEN1 Activity Occur in a Single Generation and Are Rad51 and Rad52 Dependent

2006 ◽  
Vol 26 (17) ◽  
pp. 6675-6689 ◽  
Author(s):  
Judith Lopes ◽  
Cyril Ribeyre ◽  
Alain Nicolas
Keyword(s):  
Pedigree Analysis ◽  
Model System ◽  
Yeast Cells ◽  
Single Generation ◽  
Daughter Cells ◽  
Double Deletion ◽  
Mother And Daughter ◽  
Complex Events ◽  
High Degree ◽  
Insight Into

ABSTRACT Genomes contain tandem repeat blocks that are at risk of expansion or contraction. The mechanisms of destabilization of the human minisatellite CEB1 (arrays of 36- to 43-bp repeats) were investigated in a previously developed model system, in which CEB1-0.6 (14 repeats) and CEB1-1.8 (42 repeats) alleles were inserted into the genome of Saccharomyces cerevisiae. As in human cells, CEB1 is stable in mitotically growing yeast cells but is frequently rearranged in the absence of the Rad27/hFEN1 protein involved in Okazaki fragments maturation. To gain insight into this mode of destabilization, the CEB1-1.8 and CEB1-0.6 human alleles and 47 rearrangements derived from a CEB1-1.8 progenitor in rad27Δ cells were sequenced. A high degree of polymorphism of CEB1 internal repeats was observed, attesting to a large variety of homology-driven rearrangements. Simple deletion, double deletion, and highly complex events were observed. Pedigree analysis showed that all rearrangements, even the most complex, occurred in a single generation and were inherited equally by mother and daughter cells. Finally, the rearrangement frequency was found to increase with array size, and partial complementation of the rad27Δ mutation by hFEN1 demonstrated that the production of novel CEB1 alleles is Rad52 and Rad51 dependent. Instability can be explained by an accumulation of unresolved flap structures during replication, leading to the formation of recombinogenic lesions and faulty repair, best understood by homology-dependent synthesis-strand displacement and annealing.

Molecular interactions shaping the tetraspanin web

2017 ◽  
Vol 45 (3) ◽  
pp. 741-750 ◽  
Author(s):  
Sjoerd J. van Deventer ◽  
Vera-Marie E. Dunlock ◽  
Annemiek B. van Spriel
Keyword(s):  
Molecular Interactions ◽  
Intracellular Signaling ◽  
Spatial Organization ◽  
Complex Mixture ◽  
Point Of View ◽  
Intramolecular Interactions ◽  
Fundamental Understanding ◽  
High Degree ◽  
Partner Proteins ◽  
Insight Into

To facilitate the myriad of different (signaling) processes that take place at the plasma membrane, cells depend on a high degree of membrane protein organization. Important mediators of this organization are tetraspanin proteins. Tetraspanins interact laterally among themselves and with partner proteins to control the spatial organization of membrane proteins in large networks called the tetraspanin web. The molecular interactions underlying the formation of the tetraspanin web were hitherto mainly described based on their resistance to different detergents, a classification which does not necessarily correlate with functionality in the living cell. To look at these interactions from a more physiological point of view, this review discusses tetraspanin interactions based on their function in the tetraspanin web: (1) intramolecular interactions supporting tetraspanin structure, (2) tetraspanin–tetraspanin interactions supporting web formation, (3) tetraspanin–partner interactions adding functional partners to the web and (4) cytosolic tetraspanin interactions regulating intracellular signaling. The recent publication of the first full-length tetraspanin crystal structure sheds new light on both the intra- and intermolecular tetraspanin interactions that shape the tetraspanin web. Furthermore, recent molecular dynamic modeling studies indicate that the binding strength between tetraspanins and between tetraspanins and their partners is the complex sum of both promiscuous and specific interactions. A deeper insight into this complex mixture of interactions is essential to our fundamental understanding of the tetraspanin web and its dynamics which constitute a basic building block of the cell surface.

Mobile games: players’ experiences with in-app purchases

2019 ◽  
Vol 13 (1) ◽  
pp. 62-78 ◽  
Author(s):  
Aina Ravoniarison ◽  
Cédric Benito
Keyword(s):  
Video Game ◽  
Financial Risk ◽  
Qualitative Methodology ◽  
Qualitative Data ◽  
Online Reviews ◽  
Mobile Games ◽  
Content Type ◽  
Youtube Videos ◽  
High Degree ◽  
Insight Into

PurposeThis paper aims to offer a comprehensive perspective into Free-to-Play gamers’ attitudes, feelings toward and perceived value of in-app purchases (IAPs).Design/methodology/approachThe study is based on a twofold qualitative methodology using an inductive approach: user-generated YouTube videos and gamers’ online reviews posted on Play stores.FindingsEight topics have emerged out from the qualitative data related to the characteristics of a good/bad IAP, the IAPs as downsides, the ambiguity with traditional Pay-to-Play games, the financial-risk issues, the resistance behaviors, the worries about over-spending and addiction and the frustration mechanism.Research limitations/implicationsBy focusing on IAPs, this research contributes to build an integrative overview to better understand how players deal with IAPs and how this interaction should be analyzed in the light of multiple frameworks. Emphasis is placed on a continuum of player responses from tolerant metacognition to high degree of subversion.Originality/valueA twofold netnographic approach offers a novel contribution to the field of mobile games by bringing together two materials increasingly connected to the video game universe. It also brought to the fore an experiential context by providing insight into the underlying dynamics of Player/IAP interactions.

Shaped-Beam Pattern Synthesis Through the Construction of Weighted Generalized Rayleigh Quotient

2019 ◽  
Vol 28 (1) ◽  
pp. 207-214
Author(s):  
Yin Yang ◽  
Chuan Wan ◽  
Weixing Sheng ◽  
Yubing Han ◽  
Xiaofeng Ma
Keyword(s):  
Rayleigh Quotient ◽  
Beam Pattern ◽  
Pattern Synthesis ◽  
Shaped Beam ◽  
Generalized Rayleigh Quotient

The Rutherford Atom of Culture

2018 ◽  
Vol 18 (3-4) ◽  
pp. 231-261
Author(s):  
Lawrence A. Hirschfeld
Keyword(s):  
Cultural Variation ◽  
Psychological Processes ◽  
Shared Beliefs ◽  
Northern European ◽  
Cultural Life ◽  
Wide Acceptance ◽  
Cultural Performances ◽  
State Of Affairs ◽  
High Degree ◽  
Insight Into

AbstractIncreasingly, psychologists have shown a healthy interest in cultural variation and a skepticism about assuming that research with North American and Northern European undergraduates provides reliable insight into universal psychological processes. Unfortunately, this reappraisal has not been extended to questioning the notion of culture central to this project. Rather, there is wide acceptance that culture refers to a kind of social form that is entity-like, territorialized, marked by a high degree of shared beliefs and coalescing into patterns of key values that animate a broad range of cultural performances and representations. Ironically, anthropologists and other scholars in cultural studies have overwhelmingly come to reject this view of culture. Arguably, then, the move in psychology to attend to cultural environments has paradoxically further distanced it from the fields most concerned with cultural forms. This essay reviews this state of affairs and offers a proposal how a more nuanced appreciation of cultural life can be articulated with theories and methods familiar and available to psychologists.

scholarly journals Debris-carrying camouflage among diverse lineages of Cretaceous insects

2016 ◽  
Vol 2 (6) ◽  
pp. e1501918 ◽  
Author(s):  
Bo Wang ◽  
Fangyuan Xia ◽  
Michael S. Engel ◽  
Vincent Perrichot ◽  
Gongle Shi ◽  
...  
Keyword(s):  
Fossil Record ◽  
Morphological Characteristics ◽  
Early Evolution ◽  
Behavioral Repertoire ◽  
Wood Fibers ◽  
Morphological Adaptations ◽  
Evolutionary Success ◽  
High Degree ◽  
Insect Assemblage ◽  
Insight Into

Insects have evolved diverse methods of camouflage that have played an important role in their evolutionary success. Debris-carrying, a behavior of actively harvesting and carrying exogenous materials, is among the most fascinating and complex behaviors because it requires not only an ability to recognize, collect, and carry materials but also evolutionary adaptations in related morphological characteristics. However, the fossil record of such behavior is extremely scarce, and only a single Mesozoic example from Spanish amber has been recorded; therefore, little is known about the early evolution of this complicated behavior and its underlying anatomy. We report a diverse insect assemblage of exceptionally preserved debris carriers from Cretaceous Burmese, French, and Lebanese ambers, including the earliest known chrysopoid larvae (green lacewings), myrmeleontoid larvae (split-footed lacewings and owlflies), and reduviids (assassin bugs). These ancient insects used a variety of debris material, including insect exoskeletons, sand grains, soil dust, leaf trichomes of gleicheniacean ferns, wood fibers, and other vegetal debris. They convergently evolved their debris-carrying behavior through multiple pathways, which expressed a high degree of evolutionary plasticity. We demonstrate that the behavioral repertoire, which is associated with considerable morphological adaptations, was already widespread among insects by at least the Mid-Cretaceous. Together with the previously known Spanish specimen, these fossils are the oldest direct evidence of camouflaging behavior in the fossil record. Our findings provide a novel insight into early evolution of camouflage in insects and ancient ecological associations among plants and insects.

scholarly journals Microarray Identification of Clostridium difficile Core Components and Divergent Regions Associated with Host Origin

2009 ◽  
Vol 191 (12) ◽  
pp. 3881-3891 ◽  
Author(s):  
Tavan Janvilisri ◽  
Joy Scaria ◽  
Angela D. Thompson ◽  
Ainsley Nicholson ◽  
Brandi M. Limbago ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Gene List ◽  
Core Gene ◽  
Comparative Genomic ◽  
Functional Categories ◽  
Genomic Changes ◽  
Core Components ◽  
Host Origin ◽  
High Degree ◽  
Insight Into

ABSTRACT Clostridium difficile is a gram-positive, spore-forming enteric anaerobe which can infect humans and a wide variety of animal species. Recently, the incidence and severity of human C. difficile infection has markedly increased. In this study, we evaluated the genomic content of 73 C. difficile strains isolated from humans, horses, cattle, and pigs by comparative genomic hybridization with microarrays containing coding sequences from C. difficile strains 630 and QCD-32g58. The sequenced genome of C. difficile strain 630 was used as a reference to define a candidate core genome of C. difficile and to explore correlations between host origins and genetic diversity. Approximately 16% of the genes in strain 630 were highly conserved among all strains, representing the core complement of functional genes defining C. difficile. Absent or divergent genes in the tested strains were distributed across the entire C. difficile 630 genome and across all the predicted functional categories. Interestingly, certain genes were conserved among strains from a specific host species, but divergent in isolates with other host origins. This information provides insight into the genomic changes which might contribute to host adaptation. Due to a high degree of divergence among C. difficile strains, a core gene list from this study offers the first step toward the construction of diagnostic arrays for C. difficile.

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