We present an automated algorithm for unified rejection and repair of bad trials in magnetoencephalography (MEG) and electroencephalography (EEG) signals. Our method capitalizes on cross-validation ...in conjunction with a robust evaluation metric to estimate the optimal peak-to-peak threshold – a quantity commonly used for identifying bad trials in M/EEG. This approach is then extended to a more sophisticated algorithm which estimates this threshold for each sensor yielding trial-wise bad sensors. Depending on the number of bad sensors, the trial is then repaired by interpolation or by excluding it from subsequent analysis. All steps of the algorithm are fully automated thus lending itself to the name Autoreject.
In order to assess the practical significance of the algorithm, we conducted extensive validation and comparisons with state-of-the-art methods on four public datasets containing MEG and EEG recordings from more than 200 subjects. The comparisons include purely qualitative efforts as well as quantitatively benchmarking against human supervised and semi-automated preprocessing pipelines. The algorithm allowed us to automate the preprocessing of MEG data from the Human Connectome Project (HCP) going up to the computation of the evoked responses. The automated nature of our method minimizes the burden of human inspection, hence supporting scalability and reliability demanded by data analysis in modern neuroscience.
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•A strategy for artifact rejection in M/EEG using peak-to-peak thresholds is proposed•The thresholds are estimated using cross-validation with a robust error metric•The method detects and repairs outlier data segments for each sensor•Comparison with competing methods on 200 subjects with ground truth responses
In spite of all the scholarly attention it has garnered, effectuation research continues to face a series of theoretical and methodological challenges. In order to help move effectuation research ...forward, we content-analyze a comprehensive sample of 101 effectuation articles published in JCR®-listed journals between 1998 and 2016 (inclusively), with the specific aim of uncovering the main conceptual and methodological articulations that have underpinnedeffectuationresearchto date. In doing so, we not only uncover some the field’s achievements and shortcomings but also examine the extent to which published effectuation research addresses its most salient criticisms. We build on these observations to propose three recommendations for future advances, namely (1) conceiving effectuation as a “mode of action”; (2) developing new methodological indicators centered on effectuation’s concrete manifestations; and (3) examining the underlying dynamics explaining effectuation’s antecedents and consequences.
The impact of animal manure application on soil organic carbon (SOC) stock changes is of interest for both agronomic and environmental purposes. There is a specific need to quantify SOC change for ...use in national greenhouse gas (GHG) emission inventories. We quantified the response of SOC stocks to manure application from a large worldwide pool of individual studies and determined the impact of explanatory factors such as climate, soil properties, land use and manure characteristics. Our study is based on a meta‐analysis of 42 research articles totaling 49 sites and 130 observations in the world. A dominant effect of cumulative manure‐C input on SOC response was observed as this factor explained at least 53% of the variability in SOC stock differences compared to mineral fertilized or unfertilized reference treatments. However, the effects of other determining factors were not evident from our data set. From the linear regression relating cumulative C inputs and SOC stock difference, a global manure‐C retention coefficient of 12% ± 4 (95% Confidence Interval, CI) could be estimated for an average study duration of 18 years. Following an approach comparable to the Intergovernmental Panel on Climate Change, we estimated a relative SOC change factor of 1.26 ± 0.14 (95% CI) which was also related to cumulative manure‐C input. Our results offer some scope for the refinement of manure retention coefficients used in crop management guidelines and for the improvement of SOC change factors for national GHG inventories by taking into account manure‐C input. Finally, this study emphasizes the need to further document the long‐term impact of manure characteristics such as animal species, especially pig and poultry, and manure management systems, in particular liquid vs. solid storage.
Despite its many achievements, scholarship at the intersection of entrepreneurship and cognition has focused primarily on the consequences of what happens when an entrepreneur benefits from various ...cognitive characteristics, resources, or other dispositions. As such, cognitive research in entrepreneurship continues to suffer from narrow theoretical articulations and weak conceptual foundations that lessen its contribution to the managerial sciences. To address these issues, we draw from extant work on the nature and practice of cognitive research to develop a systematic approach to study entrepreneurship cognition. To further articulate this agenda, we assess the state of the field by content‐analysing entrepreneurship cognition articles published between 1976 and 2008. We find that, although it has investigated many relevant variables, research on entrepreneurship cognition has failed to fully articulate key conceptual features of the cognitive perspective. Building on these observations, we propose concrete strategies and research questions to augment the contribution of entrepreneurship cognition research, and advance this research beyond its current focus on ‘cognitive consequences’. In particular, we illustrate the scholarly potential of disentangling the various antecedents of entrepreneurship cognition, of studying the process interactions between cognitive resources and mental representations, and of exploring the operation of entrepreneurship cognition across levels of analysis.
Experimental methods provide important advantages for advancing academic understanding of entrepreneurship. Yet, the complex and comingled relationships between some of entrepreneurship's key ...characteristics pose thorny methodological challenges to entrepreneurship researchers – notably to negotiate important tradeoffs between the ideals of external and construct validity. To facilitate the sound mobilization of experimental methods in entrepreneurship research, we present an overview of critical validity challenges plaguing entrepreneurship research experiments and assess the validation practices mobilized in 144 studies using such methods. Building on these findings, we develop a practical guide of actionable validation strategies to help experimenters navigate the above tradeoffs and conduct entrepreneurship research experiments that are realistic, theoretically meaningful, and that help establish the causal effects of their focal variables. By doing so, we contribute a set of pragmatic means to support the mobilization of experimental methods for advancing entrepreneurship research.
Experimental methods hold important advantages for advancing the theoretical and practical understanding of entrepreneurial action. The power of research experiments lies in their ability to yield convincing evidence supporting the causal effects of the factors they investigate.
Unfortunately, entrepreneurship research experiments are often criticized for offering pale copies of both the realities they attempt to model and the theoretical constructs they aim to study. The entrepreneurial process and its related activities count many intertwined characteristics – such as radical uncertainty, temporal dynamics, high personal stakes and other constraints – that can prove difficult to integrate in experimental studies. Moreover, these characteristics' comingled relationships raise important tensions with experimental methods' core principle of surgically focusing on the causal effects of a few manipulated variables. As a result, entrepreneurship research must overcome a number of validity challenges and tradeoffs in order to successfully leverage experimental methods and offer findings that convincingly support the causality of their theoretical developments.
Compounding these difficulties, the guidance typically offered in research methods textbooks tends to focus on generic issues that are altogether separate from the specific challenges of conducting valid entrepreneurship research experiments. Because of this, many research manuscripts mobilizing experimental methods arrive at the review process with important shortcomings. This threatens the field's knowledge accumulation and typically calls for authors to refine their work and collect additional data.
To help researchers face these challenges, we offer a three-part compendium focused on bolstering the validity of entrepreneurship research experiments. First, we complement the generic observations of research methods monographs by presenting an overview of the validity tradeoffs inherent to mobilizing experimental methods in entrepreneurship research – and of strategies for addressing these.
Second, and to demonstrate that overcoming these challenges is not a trivial task, we conduct a structured literature review of the external and construct validation strategies deployed in a comprehensive corpus of 144 relevant articles published in both entrepreneurship-focused journals and broader generalist journals from the applied behavioral and social sciences. Among the most positive elements emerging from our analyses, we note upward trends in the mobilization of pilot tests, in the conduct of multiple experiments within single papers as well as in the use of parallel studies using different data collection methods. We also observe increased efforts to explain the practical relevance of experimental findings. To our surprise, however, our analyses uncover downward trends in the mobilization of pre-tests to examine the research material's external validity and representativeness, as well as the continued publication of studies that do not report empirical evidence regarding their focal manipulations' construct validity. This is concerning. Such practices undermine these experiments' abilities to yield convincing evidence in support of their theorized causal effects – and for what these imply for fostering entrepreneurial action.
Third, and in light of the results obtained, we develop a practical guide of actionable strategies for navigating the validity tradeoffs of entrepreneurship research experiments. Grouping these strategies together allows us to systematize recommendations typically found across various methods monographs, thereby offering an overall scheme to help entrepreneurship researchers navigate the validity tradeoffs inherent to conducting realistic and theoretically meaningful experiments. To make our recommendations as actionable as possible, we develop an extensive step-by-step guide of design and assessment strategies relevant to entrepreneurship research experiments. The guide spans the entire research process – from conceiving an experimental study to collecting, analyzing and reporting the results. The guide also includes a number of relevant exemplars from many different studies we analyzed.
By discussing these entrepreneurship-specific validity tradeoffs and combining that with an overview of strategies for addressing them, our study offers an entrepreneurship-centered synthesis that equips entrepreneurship researchers with the necessary tools for conducting experimental research that advances understanding of the causal effects supporting entrepreneurial action and its related phenomena.
•We help guide efforts to mobilize experimental methods for advancing academic understanding of entrepreneurship.•We draw attention to the external and construct validity tradeoffs inherent to entrepreneurship research experiments.•We document extant validation practices in published entrepreneurship research experiments.•We offer a practical guide of validation recommendations, steps and strategies to help navigate the above tradeoffs.
Global surgery today has come of age. Since the publication of the Lancet Commissions report in 2015,1 global surgery is no longer considered “the neglected stepchild of global health.” (2021) ...revealed that at least 40% of in-country staff had a negative perception of visiting HIC students and practitioners, as these visitors tended to impose their medical care practices without consideration of local realities.5 This especially as graduating US general surgery residents have been found to be underprepared to perform the most important global surgery procedures.6 To move beyond the rhetoric of global surgery/health decolonization that is pervasive in the halls of HIC-based institutions, five priority action areas must be actively pursued.1 Directly fund LMIC-based organizations and institutions without pass-through funding to HIC-based institutions In global surgery, and more broadly global health and development, power resides with HIC institutions and countries. Though he is remembered for military-style disease campaigns, his work on pneumonia amongst West Indian construction laborers who lived in overcrowded shacks was one of the earliest to demonstrate the power of health systems and the need to address the social determinants of health.8 Yet, for more than a century, global health, and surgery programs supported by funding from HICs have actively promoted a disease-specific eradication strategy in LMICs. LMIC-based practitioners and researchers must demand the change and supporters in HICs must amplify their voices.4 End short-term medical mission trips that perpetuate ethnocentrism The current helicopter-in approach characterized by short term medical mission trips has serious negative consequences to the in-country's health infrastructure and delivery systems.
Ageing leads to profound alterations in the immune system and increases susceptibility to some chronic, infectious and autoimmune diseases. In recent years, widespread application of single-cell ...techniques has enabled substantial progress in our understanding of the ageing immune system. These comprehensive approaches have expanded and detailed the current views of ageing and immunity. Here we review a body of recent studies that explored how the immune system ages using unbiased profiling techniques at single-cell resolution. Specifically, we discuss an emergent understanding of age-related alterations in innate and adaptive immune cell populations, antigen receptor repertoires and immune cell-supporting microenvironments of the peripheral tissues. Focusing on the results obtained in mice and humans, we describe the multidimensional data that align with established concepts of immune ageing as well as novel insights emerging from these studies. We further discuss outstanding questions in the field and highlight techniques that will advance our understanding of immune ageing in the future.
Natural sperm selection in humans is a rigorous process resulting in the highest quality sperm reaching, and having an opportunity to fertilize, the oocyte. Relative to other mammalian species, the ...human ejaculate consists of a heterogeneous pool of sperm, varying in characteristics such as shape, size, and motility. Semen preparation in assisted reproductive technologies (ART) has long been performed using either a simple swim-up method or density gradients. Both methodologies provide highly motile sperm populations; however neither replicates the complex selection processes seen in nature. A number of methods have now been developed to mimic some of the natural selection processes that exist in the female reproductive tract. These methods attempt to select a better individual, or population of, spermatozoa when compared to classical methods of preparation. Of the approaches already tested, platforms based upon sperm membrane markers, such as hyaluronan or annexin V, have been used to either select or deselect sperm with varied success. One technology that utilizes the size, motility, and other characteristics of sperm to improve both semen analysis and sperm selection is microfluidics. Here, we sought to review the efficacy of both available and emerging techniques that aim to improve the quality of the sperm pool available for use in ART. Summary Sentence This manuscript reviews the efficacy of both available and emerging sperm selection techniques to improve the pool of sperm available for assisted reproductive technologies.
The Expanded Genetic Alphabet Malyshev, Denis A.; Romesberg, Floyd E.
Angewandte Chemie (International ed.),
October 5, 2015, Letnik:
54, Številka:
41
Journal Article
Recenzirano
Odprti dostop
All biological information, since the last common ancestor of all life on Earth, has been encoded by a genetic alphabet consisting of only four nucleotides that form two base pairs. Long‐standing ...efforts to develop two synthetic nucleotides that form a third, unnatural base pair (UBP) have recently yielded three promising candidates, one based on alternative hydrogen bonding, and two based on hydrophobic and packing forces. All three of these UBPs are replicated and transcribed with remarkable efficiency and fidelity, and the latter two thus demonstrate that hydrogen bonding is not unique in its ability to underlie the storage and retrieval of genetic information. This Review highlights these recent developments as well as the applications enabled by the UBPs, including the expansion of the evolution process to include new functionality and the creation of semi‐synthetic life that stores increased information.
Rule of three: Natural nucleic acids and the genetic information they encode are limited by the use of only four nucleotides that form two base pairs, (d)G‐(d)C and d(A)‐dT/U. In the past decade, three classes of unnatural base pairs have been developed to a high level of proof‐of‐concept. This Review summarizes their development and the potentially revolutionary applications that they are now enabling.
Although prior research has highlighted that individuals differ in their ability to identify opportunities for entrepreneurial action, little attention has been paid to the effects that differences ...among opportunities may have on their initial identification. Integrating theoretical work on the nature of entrepreneurial opportunities with cognitive science research on the use of similarity comparisons in making creative mental leaps, we develop a model of opportunity identification that includes both the independent effects of an opportunity idea's similarity characteristics and the interaction of these characteristics with an individual's knowledge and motivation. We test this model with a within-subject experiment in which we asked two samples of entrepreneurs to form beliefs about opportunity ideas for technology transfer. Results indicate that the superficial and structural similarities of technology-market combinations impact the formation of opportunity beliefs and that individual differences in prior knowledge and entrepreneurial intent moderate these relationships. In addition to casting light on cognitive reasons why some entrepreneurial opportunities may be more or less difficult to identify, our theorizing and findings point toward reasoning strategies that may facilitate the identification of multiple (and potentially more valuable) opportunities, not only for new technologies, but also for new products, services, and/or business models.
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