229 research outputs found
Reeh-Schlieder defeats Newton-Wigner: On alternative localization schemes in relativistic quantum field theory
No full textMany of the "counterintuitive" features of relativistic quantum field theory have their formal root in the Reeh-Schlieder theorem, which in particular entails that local operations applied to the vacuum state can produce any state of the entire field. It is of great interest then that I.E. Segal and, more recently, G. Fleming (in a paper entitled "Reeh-Schlieder meets Newton-Wigner") have proposed an alternative "Newton-Wigner" localization scheme that avoids the Reeh-Schlieder theorem. In this paper, I reconstruct the Newton-Wigner localization scheme and clarify the limited extent to which it avoids the counterintuitive consequences of the Reeh-Schlieder theorem. I also argue that there is no coherent interpretation of the Newton-Wigner localization scheme that renders it free from act-outcome correlations at spacelike separation
Reeh-Schlieder meets Newton-Wigner
No full textThe Reeh-Schlieder theorem asserts the vacuum and certain other states to be spacelike superentangled relative to local fields. This motivates an inquiry into the physical status of various concepts of localization. It is argued that a covariant generalization of Newton-Wigner localization is a physically illuminating concept. When analyzed in terms of nonlocally covariant quantum fields, creating and annihilating quanta in Newton-Wigner localized states, the vacuum is seen to not possess the spacelike superentanglement that the Reeh-Schlieder theorem displays relative to local fields, and to be locally empty as well as globally empty. Newton-Wigner localization is then shown to be physically interpretable in terms of a covariant generalization of the center of energy, the two localizations being identical if the system has no internal angular momentum. Finally, some of the counterintuitive features of Newton-Wigner localization are shown to have close analogues in classical special relativity
Kriegsbewirtschaftung als Faktor eines Landnutzungswandels - Das Beispiel Eichenschälwälder vor und während des Ersten Weltkrieges
No full textKriegsbewirtschaftung als Faktor eines Landnutzungswandels - Das Beispiel Eichenschälwälder vor und während des Ersten Weltkrieges
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Sequential information processing in children with and without auditory processing disorder
No full textBackground. It is a controversial issue whether sequential processing in children with auditory processing disorders (APD) is a unimodal auditory impairment. Patients and methods. Normal achieving controls (n=12; mean age: 101.1 months; SD 20.3) and children referred to clinical facilities for assessment including children with monosymptomatic APD (n=25; mean age: 90.8 months; SD 9.8), children with developmental language disorder (DLD]) + APD (n=11; mean age: 89.5 months; SD 14.9), children with dyslexia + APD (n=10; mean age: 113.8 months; SD 17.1) were compared using the subtest digit recall of the German version of the K-ABC (Melchers & Preu beta 2001) and the K-ABC subtest hand movements in the visual modality. Results. On average all groups tended to perform alike in visual sequential processing and memory (T-score>50). Normal controls (non-APD) showed on average the best test performance (T-score 57.4; SD 10.5), but the mean performance did not differ significantly from children with APD. All groups also presented on average normal test performance in the auditory modality however, children of the clinical groups were below the age mean (DLD + APD: T-W 43.1; SD 6.8; monosymptomatic APD: T-W 45.8; SD 9.8; dyslexia + APD: 46.7; SD5.8). Children with DLD + APD and those with monosymptomatic APD exhibited a significantly lower but not poor performance in auditory processing of sequences compared to their performance in visual sequential processing. The results of auditory and visual processing of sequences were significantly correlated in the clinical groups DLD + APD (0.58) and monosymptomatic APD (0.34), but not in the smallest group dyslexia + APD (0.48) and in normal achieving controls (0.32). Conclusion. On the basis of the results of the present study it may be concluded that a normal test performance on visual measure does not exclude a bimodal or pansensory seriation disorder in children with APD. It does, however, indicate the existence of a primary auditory sequential processing deficit, because at least the processing of phonological and visual stimuli was not separately carried out in children with DLD + APD
Akteursvielfalt als Entwicklungshemmnis historischer Kulturlandschaften? Eine Untersuchung der institutionellen Interaktionen am Beispiel der Fränkischen Schweiz
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