13 research outputs found
A Non-Singular One-Loop Wave Function of the Universe From a New Eigenvalue Asymptotics in Quantum Gravity
Recent work on Euclidean quantum gravity on the four-ball has proved
regularity at the origin of the generalized zeta-function built from
eigenvalues for metric and ghost modes, when diffeomorphism-invariant boundary
conditions are imposed in the de Donder gauge. The hardest part of the analysis
involves one of the four sectors for scalar-type perturbations, the eigenvalues
of which are obtained by squaring up roots of a linear combination of Bessel
functions of integer adjacent orders, with a coefficient of linear combination
depending on the unknown roots. This paper obtains, first, approximate analytic
formulae for such roots for all values of the order of Bessel functions. For
this purpose, both the descending series for Bessel functions and their uniform
asymptotic expansion at large order are used. The resulting generalized
zeta-function is also built, and another check of regularity at the origin is
obtained. For the first time in the literature on quantum gravity on manifolds
with boundary, a vanishing one-loop wave function of the Universe is found in
the limit of small three-geometry, which suggests a quantum avoidance of the
cosmological singularity driven by full diffeomorphism invariance of the
boundary-value problem for one-loop quantum theory.Comment: 21 Pages, Latex and .eps files with JHEP3 style. The discussion in
Section 5 has been improved, and Ref. 26 has been adde
Brain-based classification of youth with anxiety disorders: transdiagnostic examinations within the ENIGMA-Anxiety database using machine learning
Neuroanatomical findings on youth anxiety disorders are notoriously difficult to replicate, small in effect size and have limited clinical relevance. These concerns have prompted a paradigm shift toward highly powered (that is, big data) individual-level inferences, which are data driven, transdiagnostic and neurobiologically informed. Here we built and validated supervised neuroanatomical machine learning models for individual-level inferences, using a case–control design and the largest known neuroimaging database on youth anxiety disorders: the ENIGMA-Anxiety Consortium (N = 3,343; age = 10–25 years; global sites = 32). Modest, yet robust, brain-based classifications were achieved for specific anxiety disorders (panic disorder), but also transdiagnostically for all anxiety disorders when patients were subgrouped according to their sex, medication status and symptom severity (area under the receiver operating characteristic curve, 0.59–0.63). Classifications were driven by neuroanatomical features (cortical thickness, cortical surface area and subcortical volumes) in fronto-striato-limbic and temporoparietal regions. This benchmark study within a large, heterogeneous and multisite sample of youth with anxiety disorders reveals that only modest classification performances can be realistically achieved with machine learning using neuroanatomical data.NWORubicon 019.201SG.022Advanced Behavioural Research MethodsHealth and Well-bein
Changes in depressive symptoms and social functioning in the sequenced treatment alternatives to relieve depression study
10.1097/NMD.0b013e31822fcbe2Journal of Nervous and Mental Disease19910807-810JNMD
Covariant quantization of “massive” spin- fields in the de sitter space
We present a covariant quantization of the free "massive" spin-3/2 fields in
four-dimensional de Sitter space-time based on analyticity in the complexified
pseudo-Riemannian manifold. The field equation is obtained as an eigenvalue
equation of the Casimir operator of the de Sitter group. The solutions are
calculated in terms of coordinate-independent de Sitter plane-waves in tube
domains and the null curvature limit is discussed. We give the group
theoretical content of the field equation. The Wightman two-point function
is calculated. We introduce the
spinor-vector field operator and the Hilbert space structure.
A coordinate-independent formula for the field operator is
also presented.Comment: 24 pages, accepted for publication in Eur. Phys. J.
Saccular Abdominal Aortic Aneurysms Patient Characteristics, Clinical Presentation, Treatment, and Outcomes in the Netherlands
Objective: The aim of this was to analyze differences between saccularshaped abdominal aortic aneurysms (SaAAAs) and fusiform abdominal aortic aneurysms (FuAAAs) regarding patient characteristics, treatment, and outcome, to advise a threshold for intervention for SaAAAs.Background: Based on the assumption that SaAAAs are more prone to rupture, guidelines suggest early elective treatment. However, little is known about the natural history of SaAAAs and the threshold for intervention is not substantiated.Methods: Observational study including primary repairs of degenerative AAAs in the Netherlands between 2016 and 2018 in which the shape was registered, registered in the Dutch Surgical Aneurysm Audit (DSAA). Patients were stratified by urgency of surgery; elective versus acute (symptomatic/ruptured). Patient characteristics, treatment, and outcome were compared between SaAAAs and FuAAAs.Results: A total of 7659 primary AAA-patients were included, 6.1% (n = 471) SaAAAs and 93.9% (n = 7188) FuAAAs. There were 5945 elective patients (6.5% SaAAA) and 1714 acute (4.8% SaAAA). Acute SaAAApatients were more often female (28.9% vs 17.2%, P = 0.007) compared with acute FuAAA-patients. SaAAAs had smaller diameters than FuAAAs, in elective (53.0mm vs 61 mm, P = 0.000) and acute (68mm vs 75 mm, P = 0.002) patients, even after adjusting for sex. In addition, 25.2% of acute SaAAA-patients presented with diameters <55mm and 8.4% <45 mm, versus 8.1% and 0.6% of acute FuAAA-patients (P = 0.000). Postoperative outcomes did not significantly differ between shapes in both elective and acute patients.Conclusions: SaAAAs become acute at smaller diameters than FuAAAs in DSAA patients. This study therefore supports the current idea that SaAAAs should be electively treated at smaller diameters than FuAAAs. The exact diameter threshold for elective treatment of SaAAAs is difficult to determine, but a diameter of 45mm seems to be an acceptable threshold.Vascular Surger
Safety and efficacy of non-steroidal anti-inflammatory drugs to reduce ileus after colorectal surgery
Background: Ileus is common after elective colorectal surgery, and is associated with increased adverse events and prolonged hospital stay. The aim was to assess the role of non-steroidal anti-inflammatory drugs (NSAIDs) for reducing ileus after surgery. Methods: A prospective multicentre cohort study was delivered by an international, student- and trainee-led collaborative group. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The primary outcome was time to gastrointestinal recovery, measured using a composite measure of bowel function and tolerance to oral intake. The impact of NSAIDs was explored using Cox regression analyses, including the results of a centre-specific survey of compliance to enhanced recovery principles. Secondary safety outcomes included anastomotic leak rate and acute kidney injury. Results: A total of 4164 patients were included, with a median age of 68 (i.q.r. 57\u201375) years (54\ub79 per cent men). Some 1153 (27\ub77 per cent) received NSAIDs on postoperative days 1\u20133, of whom 1061 (92\ub70 per cent) received non-selective cyclo-oxygenase inhibitors. After adjustment for baseline differences, the mean time to gastrointestinal recovery did not differ significantly between patients who received NSAIDs and those who did not (4\ub76 versus 4\ub78 days; hazard ratio 1\ub704, 95 per cent c.i. 0\ub796 to 1\ub712; P = 0\ub7360). There were no significant differences in anastomotic leak rate (5\ub74 versus 4\ub76 per cent; P = 0\ub7349) or acute kidney injury (14\ub73 versus 13\ub78 per cent; P = 0\ub7666) between the groups. Significantly fewer patients receiving NSAIDs required strong opioid analgesia (35\ub73 versus 56\ub77 per cent; P < 0\ub7001). Conclusion: NSAIDs did not reduce the time for gastrointestinal recovery after colorectal surgery, but they were safe and associated with reduced postoperative opioid requirement