193 research outputs found

    Crossing beyond scattering amplitudes

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    We find that different asymptotic measurements in quantum field theory can be related to one another through new versions of crossing symmetry. Assuming analyticity, we conjecture generalized crossing relations for multi-particle processes and the corresponding paths of analytic continuation. We prove them to all multiplicity at tree-level in quantum field theory and string theory. We illustrate how to practically perform analytic continuations on loop-level examples using different methods, including unitarity cuts and differential equations. We study the extent to which anomalous thresholds away from the usual physical region can cause an analytic obstruction to crossing when massless particles are involved. In an appendix, we review and streamline historical proofs of four-particle crossing symmetry in gapped theories.Comment: 108 page

    Amplitudes 2023 Conference

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    The ambivalence towards neuropsychology in dementia research, diagnosis, and drug development: Myths and misconceptions.

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    Clinical assessments remain the gold standard for diagnosing neurodegenerative dementia and monitoring disease progression and treatment effects as well research. However, rapid soluble biomarker developments hold promise for increasingly targeted therapeutic approaches, targeted selection of participants in clinical trials, and more direct physiological efficacy readouts. Unfortunately, the anchoring of biomarker research to clinical symptomatology and disease progression is often based on brief and uninformative cognitive tests or screening tools that lack sensitivity to the early stages of cognitive decline. The use of these tools has given the impression that cognitive symptoms occur relatively late in the disease and that disease progression in the early stages of disease is slow. This can hinder advancements in the field and may lead to treatment interventions occurring too late. Poor cognitive test selection has likely been a factor in the failure record of dementia drug development over the last two decades. A thorough cognitive assessment is a powerful tool in the hands of an expert neuropsychologist and continues to play a key role in the accurate and early diagnosis of neurodegenerative disease. This clinical assessment is very different from the cognitive testing we traditionally see in dementia biomarker research and drug development. Yet the distinction between the two approaches is unclear to many. This paper aims to elucidate some of the myths and misconceptions around cognitive research in dementia and suggests a way forward to facilitate biomarker and drug development through the improved utility of cognitive assessment tools

    Constraints on sequential discontinuities from the geometry of on-shell spaces

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    Abstract We present several classes of constraints on the discontinuities of Feynman integrals that go beyond the Steinmann relations. These constraints follow from a geometric formulation of the Landau equations that was advocated by Pham, in which the singularities of Feynman integrals correspond to critical points of maps between on-shell spaces. To establish our results, we review elements of Picard-Lefschetz theory, which connect the homotopy properties of the space of complexified external momenta to the homology of the combined space of on-shell internal and external momenta. An important concept that emerges from this analysis is the question of whether or not a pair of Landau singularities is compatible — namely, whether or not the Landau equations for the two singularities can be satisfied simultaneously. Under conditions we describe, sequential discontinuities with respect to non-compatible Landau singularities must vanish. Although we only rigorously prove results for Feynman integrals with generic masses in this paper, we expect the geometric and algebraic insights that we gain will also assist in the analysis of more general Feynman integrals

    Do Youth with Separation Anxiety Disorder Differ in Anxiety Sensitivity From Youth with Other Anxiety Disorders?

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    Studies on the relationship between separation anxiety disorder (SAD) in childhood and panic disorder (PD) in adolescence and adulthood have yielded results which suggest a common underlying vulnerability for both disorders. In this study, we examined whether one such possible vulnerability-anxiety sensitivity-differed for youth diagnosed with SAD versus other anxiety disorders. Anxiety sensitivity was assessed using the Childhood Anxiety Sensitivity Index (CASI) in 315 clinic-referred youth (ages 6-17, 113 girls). 145 children (46%) were diagnosed with one or more primary anxiety disorder, including SAD (n = 22), generalized anxiety (GAD) (n = 79), social anxiety (SocA) (n = 55), and specific phobia (SP) (n = 45). Children with SAD reported higher levels of anxiety sensitivity and fears of physical symptoms than children with SP and SocA, but not children with GAD. We speculate that children who have SAD and GAD and high anxiety sensitivity may be more vulnerable to develop PD

    Teaching IoT Security using CTF Problems

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    In recent years, the Internet of Things (IoT) has become increasingly prevalent in modern societies. By integrating various sensors and logic controllers, IoT devices are utilized for automation in many different contexts, such as smart homes, agriculture, and manufacturing. Unfortunately, these devices are prone to have security vulnerabilities. This could be because these devices were designed with no bad actors in mind, or because their implementations contain security flaws. In order to provide more students with an opportunity to learn about potential IoT security risks, it would be highly desirable to provide hands-on exercises that are economical, scalable and safe to use. This thesis aims to develop new learning resources to support this goal, and it makes two contributions: (i) the design of a fictional factory that uses various IoT devices and protocols in an automated production line, showcasing an emerging paradigm known as Industrial IoT (IIoT); and (ii) the design and implementation of a set of Jeopardy-style CTF challenges that uses the IoT devices in this factory in a coherent storyline to test the skills and knowledge of students in various security concepts related to these devices.</p

    Effects of individual differences, society, and culture on youth-rated problems and strengths in 38 societies

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    Background: Clinicians increasingly serve youths from societal/cultural backgrounds different from their own. This raises questions about how to interpret what such youths report. Rescorla et al. (2019, European Child & Adolescent Psychiatry, 28, 1107) found that much more variance in 72,493 parents' ratings of their offspring's mental health problems was accounted for by individual differences than by societal or cultural differences. Although parents' reports are essential for clinical assessment of their offspring, they reflect parents' perceptions of the offspring. Consequently, clinical assessment also requires self-reports from the offspring themselves. To test effects of individual differences, society, and culture on youths' self-ratings of their problems and strengths, we analyzed Youth Self-Report (YSR) scores for 39,849 11-17 year olds in 38 societies. Methods: Indigenous researchers obtained YSR self-ratings from population samples of youths in 38 societies representing 10 culture cluster identified in the Global Leadership and Organizational Behavioral Effectiveness study. Hierarchical linear modeling of scores on 17 problem scales and one strengths scale estimated the percent of variance accounted for by individual differences (including measurement error), society, and culture cluster. ANOVAs tested age and gender effects. Results: Averaged across the 17 problem scales, individual differences accounted for 92.5% of variance, societal differences 6.0%, and cultural differences 1.5%. For strengths, individual differences accounted for 83.4% of variance, societal differences 10.1%, and cultural differences 6.5%. Age and gender had very small effects. Conclusions: Like parents' ratings, youths' self-ratings of problems were affected much more by individual differences than societal/cultural differences. Most variance in self-rated strengths also reflected individual differences, but societal/cultural effects were larger than for problems, suggesting greater influence of social desirability. The clinical significance of individual differences in youths' self-reports should thus not be minimized by societal/cultural differences, which-while important-can be taken into account with appropriate norms, as can gender and age differences

    Prospects for strong coupling measurement at hadron colliders using soft-drop jet mass

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    We compute the soft-drop jet-mass distribution from pppp collisions to NNLL accuracy while including nonperturbative corrections through a field-theory based formalism. Using these calculations, we assess the theoretical uncertainties on an αs\alpha_s precision measurement due to higher order perturbative effects, nonperturbative corrections, and PDF uncertainty. We identify which soft-drop parameters are well-suited for measuring αs\alpha_s, and find that higher-logarithmic resummation has a qualitatively important effect on the shape of the jet-mass distribution. We find that quark jets and gluon jets have similar sensitivity to αs\alpha_s, and emphasize that experimentally distinguishing quark and gluon jets is not required for an αs\alpha_s measurement. We conclude that measuring αs\alpha_s to the 10% level is feasible now, and with improvements in theory a 5% level measurement is possible. Getting down to the 1% level to be competitive with other state-of-the-art measurements will be challenging

    Description of the Method for Evaluating Digital Endpoints in Alzheimer Disease Study : Protocol for an Exploratory, Cross-sectional Study

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    ©Jelena Curcic, Vanessa Vallejo, Jennifer Sorinas, Oleksandr Sverdlov, Jens Praestgaard, Mateusz Piksa, Mark Deurinck, Gul Erdemli, Maximilian Bügler, Ioannis Tarnanas, Nick Taptiklis, Francesca Cormack, Rebekka Anker, Fabien Massé, William Souillard-Mandar, Nathan Intrator, Lior Molcho, Erica Madero, Nicholas Bott, Mieko Chambers, Josef Tamory, Matias Shulz, Gerardo Fernandez, William Simpson, Jessica Robin, Jón G Snædal, Jang-Ho Cha, Kristin Hannesdottir. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 10.08.2022.BACKGROUND: More sensitive and less burdensome efficacy end points are urgently needed to improve the effectiveness of clinical drug development for Alzheimer disease (AD). Although conventional end points lack sensitivity, digital technologies hold promise for amplifying the detection of treatment signals and capturing cognitive anomalies at earlier disease stages. Using digital technologies and combining several test modalities allow for the collection of richer information about cognitive and functional status, which is not ascertainable via conventional paper-and-pencil tests. OBJECTIVE: This study aimed to assess the psychometric properties, operational feasibility, and patient acceptance of 10 promising technologies that are to be used as efficacy end points to measure cognition in future clinical drug trials. METHODS: The Method for Evaluating Digital Endpoints in Alzheimer Disease study is an exploratory, cross-sectional, noninterventional study that will evaluate 10 digital technologies' ability to accurately classify participants into 4 cohorts according to the severity of cognitive impairment and dementia. Moreover, this study will assess the psychometric properties of each of the tested digital technologies, including the acceptable range to assess ceiling and floor effects, concurrent validity to correlate digital outcome measures to traditional paper-and-pencil tests in AD, reliability to compare test and retest, and responsiveness to evaluate the sensitivity to change in a mild cognitive challenge model. This study included 50 eligible male and female participants (aged between 60 and 80 years), of whom 13 (26%) were amyloid-negative, cognitively healthy participants (controls); 12 (24%) were amyloid-positive, cognitively healthy participants (presymptomatic); 13 (26%) had mild cognitive impairment (predementia); and 12 (24%) had mild AD (mild dementia). This study involved 4 in-clinic visits. During the initial visit, all participants completed all conventional paper-and-pencil assessments. During the following 3 visits, the participants underwent a series of novel digital assessments. RESULTS: Participant recruitment and data collection began in June 2020 and continued until June 2021. Hence, the data collection occurred during the COVID-19 pandemic (SARS-CoV-2 virus pandemic). Data were successfully collected from all digital technologies to evaluate statistical and operational performance and patient acceptance. This paper reports the baseline demographics and characteristics of the population studied as well as the study's progress during the pandemic. CONCLUSIONS: This study was designed to generate feasibility insights and validation data to help advance novel digital technologies in clinical drug development. The learnings from this study will help guide future methods for assessing novel digital technologies and inform clinical drug trials in early AD, aiming to enhance clinical end point strategies with digital technologies. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/35442.Peer reviewe
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