318 research outputs found
Ultraviolet–Infrared Mixing on the Noncommutative Minkowski Space in the Yang–Feldman Formalism
No full textWe study infrared divergences due to ultraviolet-infrared mixing in quantum field theory on Moyal space with Lorentzian signature in the Yang-Feldman formalism. Concretely, we are considering the and the model in arbitrary even dimension. It turns out that the situation is worse than in the Euclidean setting, in the sense that we find infrared divergences in graphs that are finite there. We briefly discuss the problems one faces when trying to adapt the nonlocal counterterms that render the Euclidean model renormalizable
The wave front set of oscillatory integrals with inhomogeneous phase function
No full textA generalized notion of oscillatory integrals that allows for inhomogeneous phase functions of arbitrary positive order is introduced. The wave front set of the resulting distributions is characterized in a way that generalizes the well-known result for phase functions that are homogeneous of order one
Noncommutative (supersymmetric) electrodynamics in the Yang-Feldman formalism
No full textWe study quantum electrodynamics on the noncommutative Minkowski space (NCQED) in the Yang-Feldman formalism. Local observables are defined by using covariant coordinates. We compute the two-point function of the interacting field strength to second order and find the infrared divergent terms already known from computations using the so-called modified Feynman rules. It is shown that these lead to nonlocal renormalization ambiguities. Also new nonlocal divergences stemming from the covariant coordinates are found. Furthermore, we study the supersymmetric extension of the model. For this, the supersymmetric generalization of the covariant coordinates is introduced. We find that the nonlocal divergences cancel. At the one-loop level, the only effect of noncommutativity is then a momentum-dependent field strength normalization. We interpret it as an acausal effect and show that its range is independent of the noncommutativity scale
Patterns of regional brain hypometabolism associated with knowledge of semantic features and categories in Alzheimer's disease
No full textThe study of semantic memory in patients with Alzheimer's disease (AD) has raised important questions about the representation of conceptual knowledge in the human brain. It is still unknown whether semantic memory impairments are caused by localized damage to specialized regions or by diffuse damage to distributed representations within nonspecialized brain areas. To our knowledge, there have been no direct correlations of neuroimaging of in vivo brain function in AD with performance on tasks differentially addressing visual and functional knowledge of living and nonliving concepts. We used a semantic verification task and resting 18-fluorodeoxyglucose positron emission tomography in a group of mild to moderate AD patients to investigate this issue. The four task conditions required semantic knowledge of (1) visual, (2) functional properties of living objects, and (3) visual or (4) functional properties of nonliving objects. Visual property verification of living objects was significantly correlated with left posterior fusiform gyrus metabolism (Brodmann's area [BA] 37/19). Effects of visual and functional property verification for nonliving objects largely overlapped in the left anterior temporal (BA 38/20) and bilateral premotor areas (BA 6), with the visual condition extending more into left lateral precentral areas. There were no associations with functional property verification for living concepts. Our results provide strong support for anatomically separable representations of living and nonliving concepts, as well as visual feature knowledge of living objects, and against distributed accounts of semantic memory that view visual and functional features of living and nonliving objects as distributed across a common set of brain area
The Effective Theory of Strings
No full textWe show that the Nambu–Goto string, and its higher dimensional generalizations, can be quantized, in the sense of an effective theory, in any dimension of the target space. The crucial point is to consider expansions around classical string configurations. We are using tools from perturbative algebraic quantum field theory, quantum field theory on curved spacetimes, and the Batalin–Vilkovisky formalism. Our model has some similarities with the Lüscher–Weisz string, but we allow for arbitrary classical background string configurations and keep the diffeomorphism invariance
On-chip Microdialysis System with Flow-through Glucose Sensing Capabilities
No full textThe published version of this article is available at http://www.journalofdst.org/May2007/pdf/VOL-1-3-ORG3-HSIEH.pd
Non-Invasive Glucose Monitoring: A Novel Approach
No full textBackground: The main concern in noninvasive (NI) glucose measurement is achieving high accuracy readings, although no blood (or other fluid) is involved in the process. Using methods based on different physical properties of a measured object can ensure the independence of each of the readings and therefore improve the validity of the end result. By using a combination of (three) independent technologies—ultrasonic, electromagnetic, and thermal—GlucoTrack™ presents a unique approach for a real-time, truly NI blood glucose spot measurement. Methods: Clinical trials were performed in two stages. Stage 1 was an initial method validation and performance verification of the device. In this stage, 50 type 1 and 2 diabetic patients, as well as healthy subjects, were evaluated with GlucoTrack against Ascensia Elite® (Bayer). In the second stage, 85 additional diabetic subjects were evaluated in half and full daytime sessions using a GlucoTrack comparison with HemoCue® (Glucose 201+). Results: A total of 135 subjects were tested during the trial period, producing 793 data pairs. Using Clarke error grid analysis, 92% of the readings fell in the clinically acceptable zones A and B, with 50% in the A zone. Mean and median relative absolute differences were 29.9 and 19.9%, respectively. Conclusions: Integrating several modalities for NI assessment of glucose level enables more accurate readings, while a possible aberration in one modality is bypassed by the others. The present generation of GlucoTrack gives promising results; however, further improvement of the accuracy of the device is needed.The published version of this article is available at http://www.journalofdst.org/amember/plugins/protect/new_rewrite/login.php?v=-any&url=/March2009/Articles/VOL-3-2-SYM4-HARMAN-BOEHM.pdf%3
Locally covariant chiral fermions and anomalies
No full textAbstractWe define chiral fermions in the presence of non-trivial gravitational and gauge background fields in the framework of locally covariant field theory. This allows to straightforwardly compute the chiral anomalies on non-compact Lorentzian spacetimes, without recourse to a weak field approximation
Hieracium murorum subsp. cophogonium Bornm. & Zahn
No full textHieracium murorum subsp. cophogonium Bornm. & Zahn in Zahn (1925: 161). Ind. loc.: “Frontière bâloise-badoise: Hohr[sic!] M i hr près Zell (A. Krafft). Trouvé aussi par Bornmüller à Tr i bsdorf, près Weimar, dans la Thuringe.” Lectotype (designated here by Gottschlich): — GERMANY. Baden-Wuerttemberg: Hohe M i hr, 11 June 1923, A. Krafft (BREG!). — Remaining syntype: GERMANY. Thuringia: Weimar, Tr i bsdorf, westl. bei d. Bahnbrücke, 8 June 1923, J. Bornmüller (B barcode B 10 0460350!). Remarks: —Although Bornmüller is co-author of the taxon, in the protologue the collection of Krafft is cited first and is here selected as lectotype.Published as part of Vogt, Robert & Gottschlich, Günter, 2023, Type material in the Hieracium (Compositae: Cichorieae) collection of Joseph Bornmüller, pp. 81-126 in Phytotaxa 613 (2) on page 102, DOI: 10.11646/phytotaxa.613.2.1, http://zenodo.org/record/834553
Sammelrezension: Revierkultur
No full textMeyer, Jochen (Red.): Berlin - ProvinzFranck, Matthias: Kultur im Revier. Die Geschichte der RuhrfestspielePankoke, Eckart/Rohe, Karl/Schütz, Erhard/Sturm, Hermann/Vogt, Jochen (Hrsg.): Revier-KulturHeinz Reif und Erhard Schutz (Hrsg.): Ruhrland-Dokumente.Bd. I: Schwarz, Georg: Kohlenpott 1931.Bd. 2: Schwarz, Georg: Der Scheinwerfer. Ein Forum der neuen SachlichkeitBd. 3: von Zahn, Peter: Schwarze Sphin
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